Researcher Database

SAKAI Ryuichi
Faculty of Fisheries Sciences Marine Life Science Marine Bioresources Chemistry

Researcher Profile and Settings


  • Faculty of Fisheries Sciences Marine Life Science Marine Bioresources Chemistry

Job Title


Research funding number

  • 20265721

Research Interests

  • Dysidea herbacea   Marine Natural Products chemistry   

Research Areas

  • Neuroscience / Neurochemistry/Neuropharmacology
  • Fisheries science / Fisheries chemistry


  •        - 1992  University of Illinois at Urban  Graduate School, Division of Chemistry  japan
  •        - 1983  University of the Ryukyus  Faculty of Science  japan

Research Activities

Published Papers


  • 酒井隆一  天然薬物の開発と応用シンポジウム講演要旨集  22nd-  1‐4  2018/10   [Not refereed] [Not invited]
  • 酒井隆一  東和食品研究振興会奨励研究報告書  2017-  1‐11  2018/12   [Not refereed] [Not invited]
  • 内舛肇, ENG Andrew, EKINS Merrick, HOOPER John, SWANSON Geoofrey T., 酒井隆一  日本水産学会大会講演要旨集  2014-  121  2014/03   [Not refereed] [Not invited]
  • SAKAI RYUICHI, SAKAI RYUICHI  トキシンシンポジウム予稿集  62nd-  89  2015/06   [Not refereed] [Not invited]
  • 飯田祐介, 中野宏治, 上田拓也, 北野雅也, 藤田雅紀, 酒井隆一  日本水産学会大会講演要旨集  2018-  107  2018/03   [Not refereed] [Not invited]
  • 藤田雅紀, 時田学幸, 石川高史, 酒井隆一  日本水産学会大会講演要旨集  2014-  121  2014/03   [Not refereed] [Not invited]
  • SAKAI RYUICHI, ICHIMORI DAICHI, ODA YUTA, FUJITA MASAKI, IMADA CHIAKI  マリンバイオテクノロジー学会大会講演要旨集  17th-  51  2015/05   [Not refereed] [Not invited]
  • 梅津早希, 今井一郎, 酒井隆一, 藤田雅紀  日本水産学会大会講演要旨集  2016-  113  2016/03   [Not refereed] [Not invited]
  • 岸伶美, 酒井隆一  日本水産学会大会講演要旨集  2014-  173  2014/03   [Not refereed] [Not invited]
  • NAKAJIMA HIROYA, ATSUMI WATARU, NAKAMURA TAKANORI, FUJITA MASAKI, SAKAI RYUICHI  日本水産学会大会講演要旨集  2015-  178  2015/03   [Not refereed] [Not invited]
  • 小田悠太, 張権, 藤田雅紀, 酒井隆一  日本水産学会大会講演要旨集  2016-  115  2016/03   [Not refereed] [Not invited]
  • 内升肇, 松村賢, 津田正史, 熊谷慶子, 赤壁麻依, 藤田雅紀, 酒井隆一  天然有機化合物討論会講演要旨集(Web)  57th-  369‐374(J‐STAGE)  2015   [Not refereed] [Not invited]
  • SAKAI RYUICHI, UCHIMASU HAJIME, TSUDA MASASHI, KUMAGAI KEIKO, AKAKABE MAI, FUJITA MASAKI  日本水産学会大会講演要旨集  2015-  141  2015/03   [Not refereed] [Not invited]
  • 宮古圭, 保野陽子, 品田哲郎, 藤田雅紀, 酒井隆一  日本水産学会大会講演要旨集  2018-  108  2018/03   [Not refereed] [Not invited]
  • FUJITA MASAKI, SAKAI RYUICHI, ISE YUJI  日本水産学会大会講演要旨集  2015-  139  2015/03   [Not refereed] [Not invited]
  • 似内梨紗, 酒井隆一, 藤田雅紀  日本水産学会大会講演要旨集  2018-  107  2018/03   [Not refereed] [Not invited]
  • 梅津早希, 今井一郎, 酒井隆一, 藤田雅紀  日本水産学会大会講演要旨集  2017-  102  2017/03   [Not refereed] [Not invited]
  • 小松代祐生, 記内優, 松本善行, 大久保勉, 伴真俊, 中山勉, 酒井隆一, 笠井久会  日本魚病学会大会プログラムおよび講演要旨  2017-  24  2017/03   [Not refereed] [Not invited]
  • 松村賢, 内舛肇, 藤田雅紀, 酒井隆一, 津田正史, 熊谷慶子, 赤壁麻衣  日本水産学会大会講演要旨集  2017-  100  2017/03   [Not refereed] [Not invited]
  • 市森大地, 藤田雅紀, 今田千秋, 酒井隆一  日本水産学会大会講演要旨集  2016-  116  2016/03   [Not refereed] [Not invited]
  • 喜田昭子, 神保充, 酒井隆一, 森本幸生, 武内良太, 田中浩士, 高橋孝志, 三木邦夫  KURRI-EKR (Web)  (16)  ROMBUNNO.P30 (WEB ONLY)  2016/12   [Not refereed] [Not invited]
  • 酒井隆一, 中野宏治, 上田拓也, 北野雅也, 小野巧, 棚野豪太, 神保充, 藤田雅紀  日本水産学会大会講演要旨集  2016-  115  2016/03   [Not refereed] [Not invited]
  • 喜田昭子, 神保充, 酒井隆一, 森本幸生, 武内良太, 田中浩士, 高橋孝志, 三木邦夫  日本結晶学会年会講演要旨集  2016-  77  2016/11   [Not refereed] [Not invited]
  • 伊藤和愛, 澤村正幸, 藤田雅紀, 酒井隆一  日本水産学会大会講演要旨集  2016-  112  2016/03   [Not refereed] [Not invited]
  • 假屋唯香, 淺沼雄太, 稲井誠, 浅川倫宏, 濱島義隆, 江木正浩, 福田裕穂, 酒井隆一, 菅敏幸  中部化学関係学協会支部連合秋季大会講演予稿集  45th-  215  2014/11   [Not refereed] [Not invited]
  • 上田拓弥, FREYMANN DM, FOCIAL PJ, 中村友香, SMITH Caleb, 井上昌, 尾島孝男, 松永智子, SWANSON GT, 酒井隆一  日本水産学会大会講演要旨集  2013-  102  2013/03   [Not refereed] [Not invited]
  • 田所洋平, 西川輝昭, 藤田雅紀, 酒井隆一  日本水産学会大会講演要旨集  2016-  115  2016/03   [Not refereed] [Not invited]
  • 松永智子, 酒井隆一  日本水産学会大会講演要旨集  2013-  96  2013/03   [Not refereed] [Not invited]
  • Uchimasu Hajime, Matsumura Ken, Tsuda Masashi, Kumagai Keiko, Akakabe Mai, Fujita M.J., Sakai Ryuichi  Symposium on the Chemistry of Natural Products, symposium papers  57-  (0)  2015   [Not refereed] [Not invited]  

    Various ionotropic receptors, metabotropic receptors and ion channels in the central nervous system play key roles in neurotransmission and homeostasis. We have been searching for neuroactive compounds interacting with these receptors or ion channels from aqueous extracts of marine benthic organisms including sponges and tunicates. Recently, we found that the extract of a Palauan Didemnidae tunicate suppressed voluntary behaviors in mice after intracerebroventricular administration. A bioassay-guided separation resulted in isolation of novel 3,4-dihydroisoquinoline alkaloids, dopargimine(1)and mellpaladines A-F(2-7). Moreover, 4-guanidino butyric acid (8) and polysulfur alkaloid lissoclibadins(9)were also identified from this specimen. The structures of 1-7 and a known 8, 9 were assigned on the basis of spectroscopic data and chemical reactions.

    Biological targets for 1-3 were screened by binding assays using 43 neuronal receptors and transporters. Functions of those compounds for high affinity receptors were also evaluated. 1 showed affinity for d-opioid receptor and determined to be an agonist. 2and 3 showed high affinity for three subtypes(5-HT1B, 5-HT1D, 5-HT5A)of serotonin receptors and shown to be a potent antagonists for 5-HT5A.

  • 境倫宏, 田中健斗, 石川裕一, 酒井隆一, 及川雅人  日本化学会講演予稿集  93rd-  (4)  1220  2013/03   [Not refereed] [Not invited]
  • UNNO Masaki, SASAKI Makoto, SAKAI Ryuichi, IKEDA SAITO Masao  X-RAYS  54-  (6)  338  -344  2012/12   [Not refereed] [Not invited]  
    Kainate receptors (KARs) are members of the ionotropic glutamate receptors (iGluR) that play variety of roles in the mammalian brain. Because KARs are comprised of five different isoform proteins, isoform selective compounds are indispensable tools in physiological researches. Dysiherbaine (DH) and neodysiherbaine A (NDH), natural toxins found from marine sponges, were shown to be potent and isoform-selective agonists for KARs. To understand structure-activity relationship of DH and NDH, numbers of analogues are synthesized, and their pharmacological activities have been evaluated in detail. Here, we determined the crystal structures of human KAR isoforms, GluK1 and GluK2, ligand-binding domain in complex with the DH analogues at high resolution. From these structures, we elucidated the relationships between the binding affinity and the molecular structure of the compounds. We also demonstrated differential recognition by some of the DH analogues of closely related isoforms GluK1 and GluK2. Further, we found that neither degree of the domain closure nor twist motion of domains directly correlated to agonist efficacy of the ligands.
  • Hideki Yamaguchi, Nachi Yoshida, Miho Takanashi, Miho Takanashi, Yuumi Ito, Yuumi Ito, Kiyoko Fukami, Kazuyoshi Yanagihara, Masakazu Yashiro, Ryuichi Sakai  PLoS ONE  9-  2014/01   [Not refereed] [Not invited]  
    Scirrhous gastric carcinoma (SGC) has the worst prognosis of all gastric cancers, owing to its rapid expansion by invasion and frequent peritoneal dissemination. Due to the increased proliferation of stromal fibroblasts (SFs) that occurs within SGC lesions and the peritoneal metastatic sites, SFs have been proposed to support the progression of this disease. However, the biological and molecular basis and the pathological role of the intercellular interaction between SGC cells and SFs remain largely unknown. In this study, we investigated the role of SFs in the invasion of the extracellular matrix (ECM) by SGC cells. When SGC cells were cocultured with SFs derived from SGC tissue on three-dimensional (3D) Matrigel, they were attracted together to form large cellular aggregates that invaded within the Matrigel. Time-lapse imaging revealed that this process was associated with extensive contraction and remodeling of the ECM. Immunofluorescence and biochemical analysis showed that SGC cells stimulate phosphorylation of myosin light chain and actomyosin-mediated mechanical remodeling of the ECM by SFs. By utilizing this assay system for inhibitor library screening, we have identified several inhibitors that potently suppress the cooperation between SGC cells and SFs to form the invasive structures. Among them, a Src inhibitor dasatinib impaired the interaction between SGC cells and SFs both in vitro and in vivo and effectively blocked peritoneal dissemination of SGC cells. These results indicate that SFs mediate mechanical remodeling of the ECM by SGC cells, thereby promoting invasion and peritoneal dissemination of SGC. © 2014 Yamaguchi et al.
  • OTSUKA KAZUNORI, ISHIKAWA YUICHI, TAKAMIZAWA SATOSHI, SAKAI RYUICHI, OIKAWA MASATO  日本化学会講演予稿集  94th-  (4)  1468  2014/03   [Not refereed] [Not invited]
  • Hideki Yamaguchi, Miho Takanashi, Miho Takanashi, Nachi Yoshida, Nachi Yoshida, Yuumi Ito, Yuumi Ito, Reiko Kamata, Kiyoko Fukami, Kazuyoshi Yanagihara, Ryuichi Sakai  Cancer Science  105-  528  -536  2014/01   [Not refereed] [Not invited]  
    Diffuse-type gastric carcinomas (DGC) exhibit more aggressive progression and poorer prognosis than intestinal-type and other gastric carcinomas. To identify potential therapeutic targets, we examined protein tyrosine phosphorylation in a panel of DGC and other gastric cancer cell lines. Protein tyrosine phosphorylation was significantly enhanced or altered in DGC cell lines compared with that in other gastric cancer cell lines. Affinity purification and mass spectrometry analysis of tyrosine-phosphorylated proteins identified Met as a protein that is preferentially expressed and phosphorylated in DGC cell lines. Unexpectedly, Met inhibitors blocked cell growth, Met downstream signaling and peritoneal dissemination in vivo in only a subset of cell lines that exhibited remarkable overexpression of Met. Likewise, only cell lines with overexpression of fibroblast growth factor receptor 2 (FGFR2) or phosphorylation of FRS2 were sensitive to an FGFR2 inhibitor. A Src inhibitor saracatinib impaired growth in cell lines that are insensitive to both Met and FGFR2 inhibitors. Saracatinib also effectively impaired peritoneal dissemination of Met-independent and FGFR2-independent SGC cells. Moreover, DGC cell lines exhibited nearly mutually exclusive susceptibility to Met, FGFR and Src inhibitors. These results suggest that DGC have distinct sensitivities to molecular target drugs and that targeting Src is beneficial in the treatment of DGC insensitive to Met and FGFR inhibition. © 2014 The Authors.
  • Takamasa Uekita, Takamasa Uekita, Satoko Fujii, Yuri Miyazawa, Reika Iwakawa, Mako Narisawa-Saito, Katsuhiko Nakashima, Koji Tsuta, Hitoshi Tsuda, Tohru Kiyono, Jun Yokota, Ryuichi Sakai  Molecular Cancer Research  12-  1449  -1459  2014/01   [Not refereed] [Not invited]  
    ©2014 AACR. Involvement of Ras in cancer initiation is known, but recent evidence indicates a role in cancer progression, including metastasis and invasion; however, the mechanism is still unknown. In this study, it was determined that human lung cancer cells with Ras mutations, among other popular mutations, showed significantly higher expression of CUB domain-containing protein 1 (CDCP1) than those without. Furthermore, activated Ras clearly induced CDCP1, whereas CDCP1 knockdown or inhibition of CDCP1 phosphorylation by Src-directed therapy abrogated anoikis resistance, migration, and invasion induced by activated-Ras. Activation of MMP2 and secretion of MMP9, in a model of Ras-induced invasion, was found to be regulated through induction of phosphorylated CDCP1. Thus, CDCP1 is required for the functional link between Ras and Src signaling during the multistage development of human malignant tumors, highlighting CDCP1 as a potent target for treatment in the broad spectrum of human cancers associated with these oncogenes.
  • 神保充, 國谷奈美, 竹内亮太, 谷本典加, 田中千瑛, 山下洋, 小池一彦, 酒井隆一  日本動物学会大会予稿集  84th-  100  2013/08   [Not refereed] [Not invited]
  • Fujita Masaki, Tokita Takayuki, Ishikawa Takafumi, Sakai Ryuichi  Symposium on the Chemistry of Natural Products, symposium papers  56-  (0)  2014   [Not refereed] [Not invited]  

    A biosynthetic gene cluster of unknown siderophore was cloned from a metagenomic library constructed from a marine sponge by function based screening method. Sequencing of the cloned DNA revealed presence of a putative biosynthetic gene cluster consisted of 15 ORFs which showed similarity to vibriobactin biosynthetic gene cluster from Vibrio cholera.

    Culture broth of the siderophore producing clone exhibited characteristic mass peak at m/z 637 which rack in the negative clone. The crude extract of the broth was fractionated by repetitive column chromatography guided by mass signal. The product was finally purified by HPLC as hexamethyl derivative. Structure of the methylated product was determined by combination of spectroscopic analysis as well as speculation from biosynthetic information to be a hexamethyl agrobactin suggested that the original product was agrobaction which has been reported from a terrestrial plant pathogen Agrobacterium tumefaciens.

    It was the first report of agrobaction from marine environmental samples and also the first heterologous production of this class of molecules.

  • 神保充, 國谷奈美, 武内良太, 田中浩士, 高橋孝志, 小池一彦, 酒井隆一, 神谷久男  日本水産学会大会講演要旨集  2012-  79  2012/09   [Not refereed] [Not invited]
  • Takuya Shirakihara, Tomonori Kawasaki, Akihiko Fukagawa, Kentaro Semba, Ryuichi Sakai, Kohei Miyazono, Keiji Miyazawa, Masao Saitoh  Cancer Science  104-  1189  -1197  2013/09   [Not refereed] [Not invited]  
    Epithelial-mesenchymal transition (EMT) is a crucial event in wound healing, tissue repair, and cancer progression in adult tissues. Transforming growth factor (TGF)-β induces EMT in mouse epithelial cells. During prolonged treatment, TGF-β successively induces myofibroblastic differentiation with increased expression of myofibroblast marker proteins, including smooth muscle α actin and calponin. We recently showed that fibroblast growth factor-2 prevented myofibroblastic differentiation induced by TGF-β, and transdifferentiated the cells to those with much more aggressive characteristics (enhanced EMT). To identify the molecular markers specifically expressed in cells undergoing enhanced EMT induced by the combination of TGF-β and fibroblast growth factor-2, we carried out a microarray-based analysis and found that integrin α3 (ITGA3) and Ret were upregulated. Intriguingly, ITGA3 was also overexpressed in breast cancer cells with aggressive phenotypes and its expression was correlated with that of δEF-1, a key regulator of EMT. Moreover, the expression of both genes was downregulated by U0126, a MEK 1/2 inhibitor. Therefore, ITGA3 is a potential marker protein for cells undergoing enhanced EMT and for cancer cells with aggressive phenotypes, which is positively regulated by δEF-1 and the MEK-ERK pathway. © 2013 Japanese Cancer Association.
  • 境倫宏, 佐々木翔太, 石川裕一, 酒井隆一, SWANSON G.T., 及川雅人  日本化学会講演予稿集  92nd-  (4)  1182  2012/03   [Not refereed] [Not invited]
  • 藤田雅紀, 中野宏治, 酒井隆一  日本水産学会大会講演要旨集  2013-  100  2013/03   [Not refereed] [Not invited]
  • Masato Kasuga, Kohjiro Ueki, Naoko Tajima, Mitsuhiko Noda, Ken Ohashi, Hiroshi Noto, Atsushi Goto, Wataru Ogawa, Ryuichi Sakai, Shoichiro Tsugane, Nobuyuki Hamajima, Hitoshi Nakagama, Kazuo Tajima, Kohei Miyazono, Kohzoh Imai  Cancer Science  104-  965  -976  2013/07   [Not refereed] [Not invited]  
    In recent years, diabetes has been shown to be associated with cancer risk, and this has led to a joint committee being formed, enlisting experts from the Japan Diabetes Society and the Japanese Cancer Association to address this issue. Epidemiological data in Japan provides evidence to demonstrate that diabetes is associated with increased risk for cancers, especially colorectal, liver, and pancreatic cancers. The mechanisms through which diabetes is assumed to promote oncogenesis include insulin resistance and associated hyperinsulinemia, hyperglycemia, and inflammation. Common risk factors for type 2 diabetes and cancer include aging, male sex, obesity, physical inactivity, inappropriate diet (excessive red/processed meat intake, inadequate vegetable/fruit/dietary fiber intake), excessive alcohol drinking, and smoking. Given that inappropriate diet/exercise, smoking and excessive alcohol drinking are common risk factors for diabetes and cancer, diet/exercise therapy, smoking cessation and alcohol moderation may be associated with decreased risk for cancer in diabetic patients. There is as yet limited evidence as to whether any particular antidiabetic agents may influence cancer risk. © 2013 The Japanese Cancer Association and the Japan Diabetes Society.
  • 喜田昭子, 神保充, 酒井隆一, 森本幸生, 武内良太, 田中浩士, 高橋孝志, 高橋孝志, 三木邦夫  KURRI KR  (193)  67  -70  2014/01   [Not refereed] [Not invited]
  • Takamasa Uekita, Satoko Fujii, Yuri Miyazawa, Akinori Hashiguchi, Hitosi Abe, Michiie Sakamoto, Ryuichi Sakai  Cancer Science  104-  865  -870  2013/07   [Not refereed] [Not invited]  
    CUB (C1r/C1s, urchin embryonic growth factor, BMP1) domain-containing protein 1 (CDCP1) has been implicated in promoting metastasis of cancer cells through several mechanisms, including the inhibition of anoikis, which is cell death triggered by the loss of extracellular matrix interactions. However, the mechanism inhibiting cell death regulated by CDCP1 remains elusive. Inhibition of CDCP1 expression using small interfering RNA (siRNA) induced the cell death of suspended cancer cells without cleaving caspase-3, a marker of apoptosis; cell death was not inhibited by a general caspase inhibitor, suggesting that the loss of CDCP1 induces caspase-independent cell death. In contrast, knockdown of CDCP1 as well as protein kinase Cδ (PKCδ), a downstream effector of CDCP1, in a suspension culture of lung cancer cells resulted in marked induction of membranous microtubule-associated protein 1 light chain 3 (LC3)-II protein, a hallmark of autophagy, and caused the formation of an autophagosome structure visualized using green fluorescent protein-tagged LC3-II. Expression and phosphorylation of exogenous CDCP1 by Fyn kinase reduced the formation of autophagosomes and inhibited phosphorylation of CDCP1 by PP2, a Src kinase inhibitor or inhibited PKCδ by rottlerin, stimulating autophagosome formation. Moreover, death of suspended lung cancer cells induced by CDCP1 siRNA or by PKCδ siRNA was reduced by the autophagy inhibitor 3-methyladenine. These results indicate that CDCP1-PKCδ signaling plays a critical role in inhibiting autophagy, which is responsible for anoikis resistance of lung cancer cells. © 2013 Japanese Cancer Association.
  • M. Kasuga, K. Ueki, N. Tajima, M. Noda, K. Ohashi, H. Noto, A. Goto, W. Ogawa, R. Sakai, S. Tsugane, N. Hamajima, H. Nakagama, K. Tajima, K. Miyazono, K. Imai  Journal of the Japan Diabetes Society  56-  374  -390  2013/06   [Not refereed] [Not invited]
  • 酒井隆一  日本薬学会年会要旨集  132nd-  (1)  175  2012/03   [Not refereed] [Not invited]
  • Yuri Miyazawa, Takamasa Uekita, Yuumi Ito, Yuumi Ito, Motoharu Seiki, Hideki Yamaguchi, Ryuichi Sakai  Molecular Cancer Research  11-  628  -637  2013/06   [Not refereed] [Not invited]  
    Complement C1r/C1s, Uegf, Bmp1 (CUB) domain-containing protein 1 (CDCP1) is a transmembrane protein that regulates anchorage-independent growth and cancer cell migration and invasion. Expression of CDCP1 is detected in a number of cancer cell lines and tissues and is closely correlated with poor prognosis. Invadopodia are actin-based protrusions on the surface of invasive cancer cells that promote the degradation of the extracellular matrix (ECM) via localized proteolysis, which is mainly mediated by membrane type 1 matrix metalloproteinase (MT1-MMP). MT1-MMP is accumulated at invadopodia by targeted delivery via membrane trafficking. The present study shows that CDCP1 is required for ECM degradation by invadopodia in human breast cancer and melanoma cells. CDCP1 localized to caveolin-1 - containing vesicular structures and lipid rafts and was detected in close proximity to invadopodia. Further biochemical analysis revealed that substantial amounts of CDCP1 existed in the Triton X-100 insoluble lipid raft fraction. CDCP1 was coimmunoprecipitated with MT1-MMP and colocalized with MT1-MMP at the vesicular structures. The siRNA-mediated knockdown of the CDCP1 expression markedly inhibited MT1-MMP - dependent ECM degradation and Matrigel invasion and reduced the accumulation of MT1-MMP at invadopodia, as shown by immunofluorescence analysis. These results indicate that CDCP1 is an essential regulator of the trafficking and function of MT1-MMP- and invadopodia-mediated invasion of cancer cells. © 2013 American Association for Cancer Research.
  • 藤田雅紀, 中野宏治, 酒井隆一  天然有機化合物討論会講演要旨集(Web)  55th-  621‐626(J‐STAGE)  2013   [Not refereed] [Not invited]
  • Mitsuru Jimbo, Yuya Suda, Kazuhiko Koike, Sachiko Nakamura-Tsuruta, Sachiko Nakamura-Tsuruta, Junko Kominami, Junko Kominami, Masugu Kamei, Jun Hirabayashi, Jun Hirabayashi, Ryuichi Sakai, Hisao Kamiya  Journal of Experimental Marine Biology and Ecology  439-  129  -135  2013/01   [Not refereed] [Not invited]  
    We previously demonstrated that the lectin SLL-2, isolated from the octocoral Sinularia lochmodes, binds to the symbiotic microalgae Symbiodinium within the coral. Upon binding SLL-2, Symbiodinium cells transform from a flagellated swimming form into a non-flagellated coccoid form, the latter morphologically similar to the symbiotic stage found in corals. However, the site recognized by the lectin on the surface of Symbiodinium cells and the transformation mechanism have yet to be elucidated. We found that the ability of SLL-2 to induce the morphological change in Symbiodinium cells can be attenuated by pretreating the cells with glycosidases or by adding the SLL-2 binding inhibitor N-acetyl-. d-galactosamine to the culture medium. These results suggest that d-galactose-containing glycoconjugates on the Symbiodinium cell surface are the key ligand through which SLL-2 induces morphological transformation. We also found that SLL-2 binds with high affinity to the Forssman antigen, and masking the binding site on Symbiodinium cells by addition of anti-Forssman glycosphingolipid antibody inhibits the binding of SLL-2 to the cells. The antibody itself or other Forssman antigen-binding proteins, such as Helix pomatia agglutinin, can transform Symbiodinium cells into the coccoid stage in the absence of SLL-2. A neutral lipid fraction prepared from cultured Symbiodinium cells reacted with the anti-Forssman glycosphingolipid antibody, supporting the hypothesis that a Forssman antigen-like glycosphingolipid on the surface of Symbiodinium cells is involved in their morphological transformation induced by the lectin SLL-2. © 2012 Elsevier B.V.
  • 上田拓弥, 井上昌, 中村友香, 松永智子, 尾島孝男, SWANSON Geffrey T., 酒井隆一  日本水産学会大会講演要旨集  2011-  115  2011/09   [Not refereed] [Not invited]
  • Masato Oikawa, Shota Sasaki, Michihiro Sakai, Yuichi Ishikawa, Ryuichi Sakai  European Journal of Organic Chemistry  5789  -5802  2012/10   [Not refereed] [Not invited]  
    The syntheses of the marine sponge-derived γ-amino carboxylic acid dysibetaine CPa and five analogs in their racemic forms were successfully performed by taking advantage of an electron-withdrawing N-(4-nitrophenyl) group in the cyclopropanation reaction, the reductive ring opening of an imide, and the ethanolysis of an N-Boc-protected imide. © 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
  • Fujita Masaki, Nakano Koji, Sakai Ryuichi  Symposium on the Chemistry of Natural Products, symposium papers  55-  (0)  PosterP  -56  2013   [Not refereed] [Not invited]  

    A siderophore, bisucaberin B, was isolated from a bacterium Tenacibaculum mesophilum separated from a marine sponge collected in the Republic of Palau. Using spectroscopic and chemical methods, the structure of bisucaberin B was determined asa linear dimer of N-hydroxy-N-succinyl cadaverine (HSC). To the best of our knowledge, it is the first report of bisucaberin B as a biosynthetic product, and also this compound is the first siderophore found from the bacteria belong to the phylum Bacteroidetes.

    The putative bisucaberin B biosynthetic gene cluster bsbA-E was cloned from a genomic library of T. mesophilum using homology sequence conserved in the known HSC based siderophore biosynthetic genes. It consists of 6 ORFs instead of 4 genes found in the other bacteria. The last HSC condensation gene was duplicated in the bsb cluster, and the additional gene which showed homology with major facilitator superfamily also existed.

    To confirm that the cloned genes were actually responsible for bisucaberin B bioproduction, two candidate enzymes for HSC dimerization, BsbD1 and BsbD2, were co-expressed with MbsA-C which were marine metagenome originated enzymes already confirmed to produce HSC in the E. coli. As a result, only BsbD2 containing recombinant clone produced bisucaberin B efficiently (production yield 16.1 mg/L) suggested that the cloned bsb cluster is bisucaberin B biosynthetic genes, and presence of only BsbD2 is enough for dimerization of HSC.

  • 松永智子, 酒井隆一, GILL Martin B., LASH‐VAN WYHE L. Leanne, SWANSON Geoffrey T.  天然有機化合物討論会講演要旨集  53rd-  409-413  -413  2011/09   [Not refereed] [Not invited]
  • 境倫宏, 佐々木翔太, 石川裕一, 酒井隆一, SWANSON G. T., 及川雅人  天然有機化合物討論会講演要旨集  53rd-  643-648  -648  2011/09   [Not refereed] [Not invited]
  • 常盤一弥, 菅俣祐太郎, 石川裕一, 酒井隆一, 及川雅人  日本化学会講演予稿集  92nd-  (4)  1180  2012/03   [Not refereed] [Not invited]
  • UNNO MASAKI, SASAKI MAKOTO, SAKAI RYUICHI, SAITO MASAO  日本結晶学会誌  54-  (6)  338  -344  2012/12   [Not refereed] [Not invited]
  • NAKAJIMA HIROYA, ATSUMI WATARU, FUJITA MASAKI, SAKAI RYUICHI  日本水産学会北海道支部大会講演要旨集  2014-  41  2014   [Not refereed] [Not invited]
  • 菅俣祐太郎, 常盤一弥, 加曽利祐基, 片山理佐, 村上悦子, 石川裕一, 酒井隆一, 及川雅人  日本化学会講演予稿集  92nd-  (4)  1181  2012/03   [Not refereed] [Not invited]
  • 松永智子, 酒井隆一  日本水産学会大会講演要旨集  2011-  92  2011/03   [Not refereed] [Not invited]
  • Ueda Takuya, Sakai Ryuichi, DM Freymann, PJ Focial, Nakamura Yuka, Smith Caleb, Inoue Akira, Ojima Takao, Matsunaga Satoko, GT Swanson  Symposium on the Chemistry of Natural Products, symposium papers  54-  (0)  585  -590  2012   [Not refereed] [Not invited]  
    Here we report the bioactivity-guided isolation of novel galectins from the marine sponge Cinachyrella sp., collected from Iriomote Island, Japan. The lectin proteins, which we refer to as the Cinachyrella galectins (CchGs), were identified as the active principles in an aqueous sponge extract that modulated the function of mammalian ionotropic glutamate receptors. Aggregation of rabbit erythrocytes by CchGs was competed most effectively by galactosides but not mannose, a profile characteristic of members of the galectin family of oligosaccharide-binding proteins. The lectin activity was remarkably stable, with only a modest loss in hemagglutination after exposure of the protein to 100℃ for 1 h, and showed little sensitivity to calcium concentration. CchG-1 and -2 appeared as 16 and l8kDa in SDS-PAGE, respectively, whereas MALDI-TOF MS indicated broad ion clusters centered at 16,216 and 16,423 respectively. The amino acid sequences of the CchGs were deduced using a combination of Edman degradation and cDNA cloning and revealed that the proteins were distant orthologues of animal prototype galectins and that multiple isolectins comprised the CchGs. The biochemical properties of the CchGs as well as their unexpected activity on mammalian excitatory amino acid receptors suggest that further analysis of these new members of the galectin family will yield further glycobiological and neurophysiological insights.
  • 海野昌喜, 海野昌喜, 海野昌喜, 篠原正将, 高山昴一郎, 田中秀治, 酒井隆一, 佐々木誠, 齋藤正男  PFシンポジウム要旨集  28th-  97(7)  2011   [Not refereed] [Not invited]
  • Takamasa Uekita, Ryuichi Sakai  Cancer Science  102-  1943  -1948  2011/11   [Not refereed] [Not invited]  
    Tumor metastasis is a complex multistep process by which cells from the primary tumor invade tissues, move through the vasculature, settle at distant sites and eventually grow to form secondary tumors. Altered tyrosine phosphorylation signals in cancer cells contribute to a number of aberrant characteristics involved in tumor invasion and metastasis. CUB domain-containing protein 1 (CDCP1) is a substrate of Src family kinases and has been shown to regulate anoikis resistance, migration and matrix degradation during tumor invasion and metastasis in a tyrosine phosphorylation-dependent manner. Knockdown of CDCP1 blocks tumor metastasis or peritoneal dissemination in vivo, without significantly affecting cell proliferation. Moreover, expression levels of CDCP1 are of prognostic value in several cancers. Here, we summarize the studies on CDCP1, focusing on structure and signal transduction, to gain insight into its role in cancer progression. Understanding the signaling pathways regulated by CDCP1 could help establish novel therapeutic strategies against the progression of cancer. © 2011 Japanese Cancer Association.
  • 櫻田剛史, GILL Martin B., FRAUSTO Shanti, COPITS Bryan, 野口恵一, 島本啓子, SWANSON Geoffrey T., 酒井隆一  天然有機化合物討論会講演要旨集  52nd-  625-630  -630  2010/09   [Not refereed] [Not invited]
  • Masato Oikawa, Shota Sasaki, Michihiro Sakai, Ryuichi Sakai  Tetrahedron Letters  52-  4402  -4404  2011/08   [Not refereed] [Not invited]  
    The cyclopropane-containing amino acid, dysibetaine CPa, isolated from Micronesian marine sponge, has been synthesized in 4.53% total yield over 12 steps starting from maleic anhydride to study the biological function in detail, by taking advantage of electron-withdrawing 4-nitrophenyl group. © 2011 Elsevier Ltd. All rights reserved.
  • 及川雅人, 及川雅人, 生駒実, 佐々木誠, 酒井隆一, SWANSON Geoffrey  天然有機化合物討論会講演要旨集  52nd-  85-90  -90  2010/09   [Not refereed] [Not invited]
  • Hideki Yamaguchi, Hideki Yamaguchi, Hideki Yamaguchi, Shuhei Yoshida, Emi Muroi, Emi Muroi, Nachi Yoshida, Nachi Yoshida, Masahiro Kawamura, Zen Kouchi, Yoshikazu Nakamura, Ryuichi Sakai, Kiyoko Fukami  Journal of Cell Biology  193-  1275  -1288  2011/06   [Not refereed] [Not invited]  
    Invadopodia are extracellular matrix-degrading protrusions formed by invasive cancer cells that are thought to function in cancer invasion. Although many invadopodia components have been identified, signaling pathways that link extracellular stimuli to invadopodia formation remain largely unknown. We investigate the role of phosphoinositide 3-kinase (PI3K) signaling during invadopodia formation. We find that in human breast cancer cells, both invadopodia formation and degradation of a gelatin matrix were blocked by treatment with PI3K inhibitors or sequestration of D-3 phosphoinositides. Functional analyses revealed that among the PI3K family proteins, the class I PI3K catalytic subunit p110α, a frequently mutated gene product in human cancers, was selectively involved in invadopodia formation. The expression of p110α with cancerous mutations promoted invadopodiamediated invasive activity. Furthermore, knockdown or inhibition of PDK1 and Akt, downstream effectors of PI3K signaling, suppressed invadopodia formation induced by p110α mutants. These data suggest that PI3K signaling via p110α regulates invadopodia-mediated invasion of breast cancer cells.
  • 喜田昭子, 神保充, 森本幸生, 酒井隆一, 神谷久男, 三木邦夫  日本蛋白質科学会年会プログラム・要旨集  10th-  112  2010/05   [Not refereed] [Not invited]
  • Chikako Ozeki, Chikako Ozeki, Chikako Ozeki, Yuichiro Sawai, Yuichiro Sawai, Tatsuhiro Shibata, Takashi Kohno, Koji Okamoto, Koji Okamoto, Jun Yokota, Fumio Tashiro, Sei Ichi Tanuma, Ryuichi Sakai, Tatsuya Kawase, Tatsuya Kawase, Issay Kitabayashi, Yoichi Taya, Yoichi Taya, Rieko Ohki, Rieko Ohki, Rieko Ohki  Journal of Biological Chemistry  286-  18251  -18260  2011/05   [Not refereed] [Not invited]  
    The common polymorphism of p53 at codon 72, either encoding proline or arginine, has drawn attention as a genetic factor associated with clinical outcome or cancer risk for the last 2 decades. We now show that these two polymorphic variants differ in protein structure, especially within the N-terminal region and, as a consequence, differ in post-translational modification at the N terminus. The arginine form (p53-72R) shows significantly enhanced phosphorylation at Ser-6 and Ser-20 compared with the proline form (p53-72P). We also show diminished Mdm2-mediated degradation of p53-72R compared with p53-72P, which is at least partly brought about by higher levels of phosphorylation at Ser-20 in p53-72R. Furthermore, enhanced p21 expression in p53-72R-expressing cells, which is dependent on phosphorylation at Ser-6, was demonstrated. Differential p21 expression between the variants was also observed upon activation of TGF-β signaling. Collectively, we demonstrate a novel molecular difference and simultaneously suggest a difference in the tumor-suppressing function of the variants. © 2011 by The American Society for Biochemistry and Molecular Biology, Inc.
  • 浅川倫宏, 大内仁志, 鈴木寛人, 磯部洋一郎, 東匠, 岡崎優子, 脇本敏幸, 古田巧, 島本啓子, 酒井隆一, 濱島義隆, 菅敏幸  天然有機化合物討論会講演要旨集  53rd-  205-210  -210  2011/09   [Not refereed] [Not invited]
  • 櫻田剛史, GILL Martin B., FRAUSTO Shanti, COPITS Bryan, 野口恵一, 島本啓子, SWANSON Geoffrey T., 酒井隆一  日本水産学会大会講演要旨集  2011-  91  2011/03   [Not refereed] [Not invited]
  • Sakai Michihiro, Sasaki Shota, Ishikawa Yuichi, Sakai Ryuichi, Swanson Geoffrey T., Oikawa Masato  天然有機化合物討論会講演要旨集  53-  (53)  643  -648  2011/09   [Not refereed] [Not invited]  
    Micronesian marine sponge Lendenfeldia chondrodes contains structurally diverse neuroactive metabolites such as dysiherbaine, neodysiherbaine, dysibetaine, dysibetaine CPa and CPb, and cribronic acid, which have received significant attention from the synthetic community as structural motifs for developing novel neuroactive compounds. It is also of our considerable interest to use these metabolites as a probe for investigating functions of synaptic receptors. In the present study, we established a synthetic route to dysibetaine CPa (1) in racemic form, which is amenable to the analog synthesis, to study the biological function as well as the structure-activity relationships. Dysibetaine CPa (1) is a betaine consists of a quaternary ammonium group and two carboxyl groups, located on a novel 1,2,3-trisubstituted cyclopropane ring. From the synthetic point of view, differentiation of the functional groups on the cyclopropane ring is essential for the total synthesis but proved to be challenging during our study because of the instability of the synthetic intermediates. Upon considerable experimentation, we discovered that the cyclopropane ring was readily constructed by the reaction of N-(4-nitrophenyl)maleimide with sulfonium ylide 3. Reductive opening of the cyclopropane-fused imide 22 with NaBH_4 proceeded chemoselectively, giving rise to hydroxyamide 23. The amide was converted to ethyl ester over two steps, and then quaternary ammonium group was introduced by way of bromide 6'. Finally, acidic hydrolysis of two esters was effected by hydrochloric acid to achieve the total synthesis of dysibetaine CPa ((±ア)-1). Total yield was 4.5% for 12 steps. Furthermore, synthesis of five analogs was performed in the present study. Our route for the racemates, thus established here, will be also expanded to the asymmetric synthesis to determine the absolute stereochemistry of 1. Preliminary study indicated that all synthetic compounds did not induce noticeable behavioral change when 20 μg was administrated in mice intracerebroventricularly, as was observed with natural product.
  • UNNO Masaki, SASAKI Makoto, SAKAI Ryuichi, IKEDA-SAITO Masao  Nihon Kessho Gakkaishi  54-  (6)  338  -344  2012   [Not refereed] [Not invited]  
    Kainate receptors (KARs) are members of the ionotropic glutamate receptors (iGluR) that play variety of roles in the mammalian brain. Because KARs are comprised of five different isoform proteins, isoform selective compounds are indispensable tools in physiological researches. Dysiherbaine (DH) and neodysiherbaine A (NDH), natural toxins found from marine sponges, were shown to be potent and isoform-selective agonists for KARs. To understand structure-activity relationship of DH and NDH, numbers of analogues are synthesized, and their pharmacological activities have been evaluated in detail. Here, we determined the crystal structures of human KAR isoforms, GluK1 and GluK2, ligand-binding domain in complex with the DH analogues at high resolution. From these structures, we elucidated the relationships between the binding affinity and the molecular structure of the compounds. We also demonstrated differential recognition by some of the DH analogues of closely related isoforms GluK1 and GluK2. Further, we found that neither degree of the domain closure nor twist motion of domains directly correlated to agonist efficacy of the ligands.
  • R. Yagi, M. Tanaka, M. Tanaka, K. Sasaki, R. Kamata, Y. Nakanishi, Y. Kanai, R. Sakai  Oncogene  30-  1413  -1421  2011/03   [Not refereed] [Not invited]  
    During the analysis of phosphotyrosine-containing proteins in scirrhous gastric carcinoma cell lines, we observed an unusual expression of Arf-GAP with Rho-GAP domain, ankyrin repeat and PH domain 3 (ARAP3), a multimodular signaling protein that is a substrate of Src family kinases. Unlike other phosphotyrosine proteins, such as CUB domain-containing protein 1 (CDCP1) and Homo sapiens chromosome 9 open reading frame 10/oxidative stress-associated Src activator (C9orf10/Ossa), which are overexpressed and hyperphosphorylated in scirrhous gastric carcinoma cell lines, ARAP3 was underexpressed in cancerous human gastric tissues. In this study, we found that overexpression of ARAP3 in the scirrhous gastric carcinoma cell lines significantly reduced peritoneal dissemination. In vitro studies also showed that ARAP3 regulated cell attachment to the extracellular matrix, as well as invasive activities. These effects were suppressed by mutations in the Rho-GTPase-activating protein (GAP) domain or in the C-terminal two tyrosine residues that are phosphorylated by Src. Thus, the expression and phosphorylation state of ARAP3 may affect the invasiveness of cancer by modulating cell adhesion and motility. Our results suggest that ARAP3 is a unique Src substrate that suppresses peritoneal dissemination of scirrhous gastric carcinoma cells. © 2011 Macmillan Publishers Limited All rights reserved.
  • Matsunaga Satoko, Sakai Ryuichi, Gill Martin B., Lash-Van Wyhe Leanne, Swanson Geoffrey T.  天然有機化合物討論会講演要旨集  53-  (53)  409  -413  2011/09   [Not refereed] [Not invited]  
    Aculeines (ACUs) are new peptide toxins isolated from the marine sponge A. aculeata collected at Iriomote, Okinawa. ACUs exhibited neurotoxicity through disrupting cell membrane and inducing robust influx of Ca^<2+> ions. ACUs are modified by long-chain polyamines (LCPAs) at the Nterminal amino acid. Amino acid sequence of the peptide portion of ACU-A was determined on the basis of Edman degradation, nucleotide sequence analysis, and peptide-mass mapping to be a 44-amino acid polypeptide. The peptide-mass mapping for ACU-B showed that it shares the same peptide portion with ACU-A. The nucleotide sequence analysis suggested that the Nterminal of ACU-A/B to be Trp, however; their structures were difficult to be elucidated because of a minute amount of peptides available and highly unusual modification by LCPA. In the present study, we isolated Nterminal fragments E and E' obtained from enzyme digest of ACU-A and B, respectively. We also found a novel LCPA derivative protoaculaine (1) that possibly represents the structures of the Nterminal portion of ACUs form the aqueous extract. Here we report the structure elucidation of those compounds.
  • 佐々木翔太, 境倫宏, 酒井隆一, 及川雅人  日本化学会講演予稿集  91st-  (4)  1179  2011/03   [Not refereed] [Not invited]
  • Asakawa Tomohiro, Ohuchi Hitosi, Suzuki Hiroto, Isobe Youichiro, Higashia Takumi, Okazakia Yuko, Wakimoto Toshiyuki, Furuta Takumi, Shimamoto Keiko, Sakai Ryuichi, Hamashima Yoshitaka, Kan Toshiyuki  天然有機化合物討論会講演要旨集  53-  (53)  205  -210  2011/09   [Not refereed] [Not invited]  
    Recently, kainoids, such as kainic acid, have received significant attention due to their potent binding affinity for ionotropic glutamate receptors (iGluRs). iGluRs are involved in important neurophysiological processes, such as memory and learning. Although many synthetic investigations of kainoids have been reported to date, efficient synthetic methods are still strongly required. During the pioneering investigations on acromelic acid A, isolated by the Shirahama group, it was discovered that a synthetic derivative, methoxyphenyl kainic acid, possessed more potent activity than the natural compound. Inspired by this interesting structure-activity relationship, we launched an investigation into the development of efficient synthetic methods for achieving MFPA and phenylkainic acid. In our synthetic strategy, we envisioned that the three consecutive chiral centers were constructed based on the stereochemistry of the C4 position. We employed our asymmetric intermolecular C-H insertion reaction assisted by the chiral auxiliary using diazo ester and cyclohexadiene to afford the desired diene ester in high yield with good diastereoselectivity. After the conversion into the lactone by successive ozonolysis of cyclohexadiene, nitrogen was installed with Ns amide to give the corresponding hemiaminal. The reduction of the aminal and deprotection of the acetal induced the cyclization to construct a pyrrolidine ring with the correct stereochemistry. Introduction of two cyano groups were performed by diastereoselective Strecker-type reaction and Mitsunobu reaction. Finally, hydrolysis of the two cyano groups gave the synthetic kainoids. Furthermore, several investigations using the synthesized kainoids have elucidated that these compounds selectively bind to iGluRs and are equally effective for mice in vivo.
  • 酒井隆一  化学と生物  47-  (10)  674  -675  2009/10   [Not refereed] [Not invited]
  • 喜田昭子, 神保充, 森本幸生, 酒井隆一, 神谷久男, 三木邦夫  PFシンポジウム要旨集  27th-  42  2010   [Not refereed] [Not invited]
  • 櫻田剛史, GILL Martin B., FRAUSTO Shanti, COPITS Bryan, 野口恵一, 島本啓子, SWANSON Geoffrey T., 酒井隆一  日本水産学会北海道支部大会講演要旨集  2010-  22  2010   [Not refereed] [Not invited]
  • 喜田昭子, 神保充, 森本幸生, 酒井隆一, 神谷久男, 三木邦夫  日本結晶学会年会講演要旨集  2010-  123  2010   [Not refereed] [Not invited]
  • Hitoyasu Futami, Ryuichi Sakai  Cancer Letters  297-  220  -225  2010/11   [Not refereed] [Not invited]  
    Recently, gene amplification and gain-of-function mutations of ALK have been found in some neuroblastoma cell lines and clinical tumor samples. We have previously reported that knockdown of ALK by RNAi induced apoptosis in neuroblastoma cells with gene amplification of ALK. We report that all-trans retinoic acid (ATRA) downregulates ALK in neuroblastoma cell lines. Downregulation of ALK protein by ATRA was accompanied by apoptosis in neuroblastoma cells with gene amplification or gain-of-function mutation of ALK but not in neuroblastoma cells without these genetic alterations. These results suggest that ALK downregulation by ATRA might lead to apoptosis in neuroblastoma cells with activated ALK. © 2010 Elsevier Ireland Ltd.
  • Tatsuya Tazaki, Takaaki Sasaki, Kenta Uto, Norimasa Yamasaki, Satoshi Tashiro, Ryuichi Sakai, Minoru Tanaka, Hideaki Oda, Zen Ichiro Honda, Zen Ichiro Honda, Hiroaki Honda  Hepatology  52-  1089  -1099  2010/09   [Not refereed] [Not invited]  
    p130Cas, Crk-associated substrate (Cas), is an adaptor/scaffold protein that plays a central role in actin cytoskeletal reorganization. We previously showed that mice in which Cas was deleted (Cas -/- ) died in utero because of early cardiovascular maldevelopment. To further investigate the in vivo roles of Cas, we generated mice with a hypomorphic Cas allele lacking the exon 2-derived region (Cas Δex2/Δex2 ), which encodes Src homology domain 3 (SH3) of Cas. Cas Δex2/Δex2 mice again died as embryos, but they particularly showed progressive liver degeneration with hepatocyte apoptosis. Because Cas expression in the liver is preferentially detected in sinusoidal endothelial cells (SECs), the observed hepatocyte apoptosis was most likely ascribable to impaired function of SECs. To address this possibility, we stably introduced a Cas mutant lacking the SH3 domain (Cas ΔSH3) into an SEC line (NP31). Intriguingly, the introduction of Cas ΔSH3 induced a loss of fenestrae, the characteristic cell-penetrating pores in SECs that serve as a critical route for supplying oxygen and nutrients to hepatocytes. The disappearance of fenestrae in Cas ΔSH3-expressing cells was associated with an attenuation of actin stress fiber formation, a marked reduction in tyrosine phosphorylation of Cas, and defective binding of Cas to CrkII. Conclusion: Cas plays pivotal roles in liver development through the reorganization of the actin cytoskeleton and formation of fenestrae in SECs. Copyright © 2010 by the American Association for the Study of Liver Diseases.
  • Hideki Yamaguchi, Hideki Yamaguchi, Hideki Yamaguchi, Shuhei Yoshida, Emi Muroi, Masahiro Kawamura, Zen Kouchi, Yoshikazu Nakamura, Ryuichi Sakai, Kiyoko Fukami  Cancer Science  101-  1632  -1638  2010/07   [Not refereed] [Not invited]  
    Invadopodia are ventral cell protrusions formed in invasive cancer cells. Because invadopodia have extracellular matrix (ECM) degradation activity, they are thought to function in cancer invasion. In this study, we examined the roles of phosphatidylinositol 4,5-bisphosphate [PI(4,5)P 2 ] and PI(4,5)P 2 -producing enzymes in invadopodia formation in MDA-MB-231 human breast cancer cells. Immunofluorescence analysis showed that PI(4,5)P 2 accumulates at invadopodia on the ventral cell surface. Injection of an anti-PI(4,5)P 2 antibody inhibited invadopodia formation along with gelatin degradation activity. Sequestering of PI(4,5)P 2 by overexpression of the phospholipase C (PLC) δ1-pleckstrin homology (PH) domain, a specific probe for PI(4,5)P 2 , also blocked invadopodia formation, while a mutated PLCδ1-PH domain that lacks PI(4,5)P 2 -binding activity had no effect. Cellular PI(4,5)P 2 production is mainly mediated by type-I phosphatidylinositol 4-phosphate 5-kinase (PIP5KI) family proteins, which include PIP5KIα, Iβ, and Iγ. Real-time quantitative PCR analysis showed that PIP5KIα is a dominant isoform expressed in MDA-MB-231 cells. Knockdown of PIP5KIα by small-interfering RNA (siRNA) inhibited invadopodia formation and gelatin degradation. Immunofluorescence analysis revealed that endogenous PIP5KIα protein localizes at invadopodia, which is corroborated by the observation that exogenously expressed green fluorescent protein (GFP)-fused PIP5KIα protein also accumulates at gelatin degradation sites. These results indicate that localized production of PI(4,5)P 2 by PIP5KIα is required for invadopodia formation and ECM degradation by human breast cancer cells. © 2010 Japanese Cancer Association.
  • 松永智子, 酒井隆一, 神保充, GILL Martin B., SWANSON Geoffey T., 神谷久男  天然有機化合物討論会講演要旨集  51st-  599-604  -604  2009/09   [Not refereed] [Not invited]
  • Yuri Miyazawa, Yuri Miyazawa, Takamasa Uekita, Nobuyoshi Hiraoka, Satoko Fujii, Tomoo Kosuge, Yae Kanai, Yoshihisa Nojima, Ryuichi Sakai  Cancer Research  70-  5136  -5146  2010/06   [Not refereed] [Not invited]  
    CUB domain-containing protein 1 (CDCP1) is a membrane protein that is highly expressed in several solid cancers. We reported previously that CDCP1 regulates anoikis resistance as well as cancer cell migration and invasion, although the underlying mechanisms have not been elucidated. In this study, we found that expression of CDCP1 in pancreatic cancer tissue was significantly correlated with overall survival and that CDCP1 expression in pancreatic cancer cell lines was relatively high among solid tumor cell lines. Reduction of CDCP1 expression in these cells suppressed extracellular matrix (ECM) degradation by inhibiting matrix metalloproteinase-9 secretion. Using the Y734F mutant of CDCP1, which lacks the tyrosine phosphorylation site, we showed that CDCP1 regulates cell migration, invasion, and ECM degradation in a tyrosine phosphorylation-dependent manner and that these CDCP1-associated characteristics were inhibited by blocking the association of CDCP1 and protein kinase Cδ (PKCδ). CDCP1 modulates the enzymatic activity of PKCδ through the tyrosine phosphorylation of PKCδ by recruiting PKCδ to Src family kinases. Cortactin, which was detected as a CDCP1-dependent binding partner of PKCδ, played a significant role in migration and invasion but not in ECM degradation of pancreatic cells. These results suggest that CDCP1 expression might play a crucial role in poor outcome of pancreatic cancer through promotion of invasion and metastasis and that molecules blocking the expression, phosphorylation, or the PKCδ-binding site of CDCP1 are potential therapeutic candidates. ©2010 AACR.
  • Mitsuru Jimbo, Hiroshi Yamashita, Hiroshi Yamashita, Kazuhiko Koike, Kazuhiko Koike, Ryuichi Sakai, Ryuichi Sakai, Hisao Kamiya  Fisheries Science  76-  355  -363  2010/03   [Not refereed] [Not invited]  
    We report herein the presence of a lectin in the scleractinian coral Ctenactis (Fungia) echinata. The lectin bound preferentially to lactose, melibiose, and d-galactose. The purified lectin CecL was composed of several isolectins, and it was found to have a molecular mass of 67.4 kDa via gel filtration. Glycopeptidase F-treated CecL showed a single band at 32.5 kDa. The mass/charge ratios of the reduced CecL peaks were equivalent to half those of the native peaks. These results suggest that CecL is composed of two glycosylated polypeptides linked by interchain disulfide bonds. In a biological activity test using a zooxanthellal culture (Dinoflagellate Symbiodinium) clonally isolated from Fungia cf. fungites, CecL transformed the flagellated motile form of Symbiodinium into the nonmotile coccoid form, a form equivalent to the symbiotic stage. The activity of CecL on Symbiodinium cells was concentration dependent, and 100 μg/ml CecL arrested Symbiodinium cells in the coccoid form for 5 days. CecL also suppressed the growth of Symbiodinium cells, unlike the octocoral lectin derived from Sinularia lochmodes, which arrests Symbiodinium cells in the coccoid form but does not affect the growth of the coccoid. This result provides further evidence that coral lectins play a role in symbiont engagement and maintenance in zooxanthellae-coral symbiosis. © The Japanese Society of Fisheries Science 2010.
  • M. B. Gill, S. Frausto, M. Ikoma, M. Sasaki, M. Oikawa, M. Oikawa, R. Sakai, G. T. Swanson  British Journal of Pharmacology  160-  1417  -1429  2010/01   [Not refereed] [Not invited]  
    Background and purpose: A new class of heterotricyclic glutamate analogues recently was generated by incorporating structural elements of two excitotoxic marine compounds, kainic acid and neodysiherbaine A. Rather than acting as convulsants, several of these 'IKM' compounds markedly depressed CNS activity in mice. Here, we characterize the pharmacological profile of the series with a focus on the most potent of these molecules, IKM-159. Experimental approach: The pharmacological activity and specificity of IKM compounds were characterized using whole-cell patch clamp recording from neurons and heterologous receptor expression systems, in combination with radioligand binding techniques. Key results: The majority of the IKM compounds tested reduced excitatory synaptic transmission in neuronal cultures, and IKM-159 inhibited synaptic currents from CA1 pyramidal neurons in hippocampal slices. IKM-159 inhibited glutamate-evoked whole-cell currents from recombinant GluA2- and GluA4-containing α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate (AMPA) receptors most potently, whereas kainate and NMDA receptor currents were not reduced by IKM-159. Antagonism of steady-state currents was agonist concentration dependent, suggesting that its mechanism of action was competitive, although it paradoxically did not displace [ 3 H]-AMPA from rec eptor binding sites. IKM-159 reduced spontaneous action potential firing in both cultured hippocampal neurons in control conditions and during hyperactive states in an in vitro model of status epilepticus. Conclusions and implications: IKM-159 is an AMPA receptor-selective antagonist. IKM-159 and related nitrogen heterocycles represent structurally novel AMPA receptor antagonists with accessible synthetic pathways and potentially unique pharmacology, which could be of use in exploring the role of specific populations of receptors in neurophysiological and neuropathological processes. © 2010 The British Pharmacological Society.
  • 中村友香, SWANSON Geffrey T., LASH Lianne L., 酒井隆一  日本水産学会大会講演要旨集  2009-  131  2009/03   [Not refereed] [Not invited]
  • 松永智子, 酒井隆一, 神保充, 神谷久男  日本水産学会大会講演要旨集  2009-  131  2009/03   [Not refereed] [Not invited]
  • WATANABE TOMOKO, TSUBONE KOICHI, OIKAWA MASATO, SASAKI MAKOTO, SAKAI RYUICHI, UNNO MASAKI, SAITO MASAO  日本化学会講演予稿集  89th-  (2)  1440  2009/03   [Not refereed] [Not invited]
  • Masamitsu Tanaka, Masamitsu Tanaka, Reiko Kamata, Kazuyoshi Yanagihara, Ryuichi Sakai  Cancer Science  101-  87  -93  2010/01   [Not refereed] [Not invited]  
    Interaction of the Eph family of receptor protein tyrosine kinases and their ligands, ephrin family members, induces bidirectional signaling through cell-cell contacts. High expression of B-type ephrin is associated with high invasion potential of tumors, and we previously observed that signaling through the C-terminus of ephrin-B1 mediates the migration and invasion of cells, and is involved in the promotion of carcinomatous peritonitis in vivo. Here we show that the intracellular introduction of a synthetic peptide derived from ephrin-B1 C-terminus blocks ephrin-B1 mediated signaling in scirrhous gastric cancer cells. Treatment of cancer cells with a fusion peptide consisting of HIV-TAT and amino acids 331-346 of ephrin-B1 (PTD-EFNB1-C) suppressed the activation of RhoA, mediated by the association of ephrin-B1 with an adaptor protein Dishevelled, and also inhibited extracellular secretion of metalloproteinase. Moreover, injection of PTD-EFNB1-C peptide into the peritoneal cavity of nude mice suppressed carcinomatous peritonitis of intraperitoneally transplanted scirrhous gastric cancer cells. These results indicate the possible application of ephrin-B1 C-terminal peptide to develop novel protein therapy for scirrhous gastric carcinoma, especially in the stage of tumor progression, including peritoneal dissemination. © 2009 Japanese Cancer Association.
  • Sakurada Tsuyoshi, Gill Martin B, Frausto Shanti, Copits Bryan, Noguchi Keiichi, Shimamoto Keiko, Swanson Geoffrey T., Sakai Ryuichi  天然有機化合物討論会講演要旨集  52-  (52)  625  -630  2010/09   [Not refereed] [Not invited]  
    Marine benthi organisms have yielded a variety of natural products with neuropharmacological applications. Here we describe the isolation and pharmacological characterization of four novel, neurologically active 8-oxoderivatives of purine, 1-4, isolated from Haplosclerida sponges collected in the Republic of Palau. The structure of 1 was determined based on spectral data and was confirmed by X-ray crystallography. The structures of 2-4 were determined similarly using spectral data by analogy of that of 1. Compound 1 induced convulsant behavior upon intracerebroventricular injection into mice, with a CD_<50> value of 2,4 nmol/mouse. Purines 2-4 were active in mouse bioassays at higher doses. The seizurogenic activity observed with 1 was correlated with inhibition of neruonal GABAergic transmission, with only a modest mpact of excitatory signaling, in electrophysiological recordings from hippoampal neurons in cultured and acute brain slice preparations. Despite having a purine template structure, the inhibitory activity of 1 was not prevented by a nonselective adenosine receptor antagonist. The natural product 1 therefore represents a novel substituted purine that elicits convulsions through its actions on inhibitory neurotransmission. The four 8-oxoisoguanine analogs comprise a new family of compounds closely related in structure to both important endogenous neurosignaling molecules and commonly used CNS stimulants.
  • OHIRA NAO, TSUBONE KOICHI, OIKAWA MASATO, SASAKI MAKOTO, SAKAI RYUICHI  日本化学会講演予稿集  89th-  (2)  1440  2009/03   [Not refereed] [Not invited]
  • Oikawa Masato, Ikoma Minoru, Sasaki Makoto, Sakai Ryuichi, Swanson Geoffrey T.  天然有機化合物討論会講演要旨集  52-  (52)  85  -90  2010/09   [Not refereed] [Not invited]  
    Ionotropic glutamate receptors (iGluRs) are involved in higher brain functions such as memory and learning, nociception, and a number of brain disorders. Here, we report the synthesis of twelve artificial glutamate analogs whose core structure was inspired by two marine-derived excitatory amino acids, dysiherbaine and kainia acid. Four 7-oxznorbornenes, 2a-2d, were prepared in two steps, starting from and Ugi four component coupling reaction followed by spontaneous Diels-Alder reaction between 2-furfural, 3-iodoacrylic acid, 4-methoxybenzylamine, and benzyl isocyanide. An unprecedented domino metathesis reaction with less reactive vinyl acetate as a cross metathesis substrate was then performed with the Hoveyda-Grubbs second-generation catalyst, to successfully deliver four heterotricycles 3a-3d in good yiels. After functional group transformations followed by diversification at the C-ring, twelve artificial glutamate analogs 6a-6d, 7a-7d, 8a-8d were synthesized in total 7.2-25.8% yield for 13-15 steps. Mice in vivo assays indicated that all analogs are biologically active; namely, 6b, 7a, 7b, and 8b produce hyperactivity in injected i.c.v., whereas other analogs induce hypoactiity in the animals. In vitro electrophysiological assays showed that some hypoactive analogs inhibit spontaneous excitatory synaptic currents in hippocampal neurons and glutamate-evoked currents from recombinant AMPA receptors. With these pharmacological profiles, synthesis of other analogs werer further performed, and pyrrolidone dicarboxylic acid analog IKM-159 was discovered as a more potent, AMPA receptor-selective antagonist.
  • 酒井隆一  生物の科学 遺伝  63-  (2)  60-64  -64  2009/03   [Not refereed] [Not invited]
  • 松永智子, 酒井隆一, 神保充  日本水産学会大会講演要旨集  2009-  87  2009/09   [Not refereed] [Not invited]
  • 海野昌喜, 海野昌喜, 篠原正将, 高山昴一郎, 渡邉朋子, 田中秀治, 酒井隆一, 佐々木誠, 齋藤正男  生化学  ROMBUNNO.2T4A-6  2009/09   [Not refereed] [Not invited]
  • 田中秀治, 海野昌喜, 海野昌喜, 篠原正将, 高山昂一郎, 渡邉朋子, 酒井隆一, 佐々木誠, 齊藤正男  東北大学多元物質科学研究所研究発表会講演予稿集  9th-  142  2009   [Not refereed] [Not invited]
  • 海野昌喜, 海野昌喜, 篠原正将, 高山昴一郎, 渡邉朋子, 田中秀治, 酒井隆一, 佐々木誠, 齋藤正男  日本結晶学会年会講演要旨集  2009-  32  2009   [Not refereed] [Not invited]
  • Hitoyasu Futami, Ryuichi Sakai  Cancer Science  100-  1034  -1039  2009/06   [Not refereed] [Not invited]  
    The receptor tyrosine kinase RET is expressed in a number of neuroblastoma tissues and cell lines, but its role in neuroblastoma remains to be determined. In this study, we examined the roles of RET protein in neuroblastoma by the RNA interference technique using the NB-39-nu neuroblastoma cell line. NB-39-nu neuroblastoma cells show high expression and elevated tyrosine phosphorylation of RET, although short interfering RNA against RET (RET siRNA) did not significantly inhibit cell proliferation or suppression of basal levels of phosphorylation of extracellular regulated kinase (ERK)1/2 or protein kinase B (AKT). By the addition of glial cell line-derived neurotrophic factor (GDNF), both the expression and phosphorylation of RET and the phosphorylation of ERK1/2 and AKT were further increased, whereas cell proliferation was not stimulated under normal culture conditions. However, proliferation of cells cultured under non-adherent conditions was significantly increased by GDNF. The increased proliferation was suppressed by RET siRNA, which also caused inhibition of the phosphorylation of ERK1/2 and AKT. These results suggest that RET signaling plays an important role in GDNF-induced enhancement of non-adherent proliferation of NB-39-nu cells, which might contribute to the metastasis of neuroblastoma. (Cancer Sci 2009; 100: 1034-1039). © 2009 Japanese Cancer Association.
  • Jun Ichiro Ikeda, Tomofumi Oda, Tomofumi Oda, Masayoshi Inoue, Takamasa Uekita, Ryuichi Sakai, Meinoshin Okumura, Katsuyuki Aozasa, Eiichi Morii  Cancer Science  100-  429  -433  2009/04   [Not refereed] [Not invited]  
    CUB domain containing protein (CDCP1), a transmembrane protein with intracellular tyrosine residues which are phosphorylated upon activation, is supposed to be engaged in proliferative activities and resistance to apoptosis of cancer cells. Expression level of CDCP1 was examined in lung adenocarcinoma, and its clinical implications were evaluated. CDCP1 expression was immunohistochemically examined in lung adenocarcinoma from 200 patients. Staining intensity of cancer cells was categorized as low and high in cases with tumor cells showing no or weak and strong membrane staining, respectively. MIB-1 labeling index was also examined. There were 113 males and 87 females with median age of 63 years. Stage of disease was stage I in 144 cases (72.0%), II in 19 (9.5%), and III in 37 (18.5%). Sixty of 200 cases (30.0%) were categorized as CDCP1-high, and the remaining as CDCP1-low. Significant positive correlation was observed between CDCP1-high expression and relapse rate (P < 0.0001), poor prognosis (P < 0.0001), MIB-1 labeling index (P < 0.0001), and occurrence of lymph node metastasis (P = 0.0086). There was a statistically significant difference in disease-free survival (DFS) (P < 0.0001) and overall survival (OS) rates (P < 0.0001) between patients with CDCP1-high and CDCP1-low tumors. Univariate analysis showed that lymph node status, tumor stage, and CDCP1 expression were significant factors for both OS and DFS. Multivariate analysis revealed that only CDCP1 expression was an independent prognostic factor for both OS and DFS. CDCP1 expression level is a useful marker for prediction of patients with lung adenocarcinoma. © 2009 Japanese Cancer Association.
  • Kotaro Azuma, Tomohiko Urano, Tomohiko Urano, Kuniko Horie-Inoue, Shin Ichi Hayashi, Ryuichi Sakai, Yasuyoshi Ouchi, Satoshi Inoue, Satoshi Inoue, Satoshi Inoue, Satoshi Inoue  Cancer Research  69-  2935  -2940  2009/04   [Not refereed] [Not invited]  
    Estrogen receptor a (ERa) is a nuclear receptor that functions as a ligand-activated transcription factor. Besides its genomic action in nuclei, ERa could exert nongenomic actions at theplasma membrane. To investigate the mechanism underlyingthe nongenomic action of ERa in breast cancer cells, we generated a construct of membrane-targeted ERa (memER),an expression vector of ERa without the nuclear localizingsignal and including instead the membrane-targeting sequence of Src kinase. MemER was stably expressed in humanbreast cancer MCF-7 cells. Cell migration test and tumorigenicassay in nude mice revealed that the in vitro motility and the in vivo proliferation activity of MCF-7 cells expressing memER were significantly enhanced compared with those of vector-transfected cells. Interestingly, the acetylation level of tubulin in memER-overexpressing cells was lower than that in control cells. We found that histone deacetylase (HDAC) 6 translocated to the plasma membrane shortly after estrogen stimulation, and rapid tubulin deacetylation subsequently occurred. We also showed that memER associated with HDAC6 in a ligand-dependent manner. Although tamox- ifen is known for its antagonistic role in the ERa genomic action in MCF-7 cells, the agent showed an agonistic function in the memER-HDAC6 association and tubulin deacetylation. These findings suggest that ERa ligand dependently forms a complex with HDAC6 and tubulin at the plasma membrane. Estrogen-dependent tubulin deacetylation could provide new evidence for the nongenomic action of estrogen, which potentially contributes to the aggressiveness of ERa-positive breast cancer cells. ©2009 American Association for Cancer Research .
  • Matsunaga S., Sakai R., Jimbo M., Gill Martin B., Swanson Geoffrey T., Kamiya H.  天然有機化合物討論会講演要旨集  51-  (51)  599  -604  2009/09   [Not refereed] [Not invited]  
    In our quest for neurotoxic copounds in marine benthic organisms, we discovered novel functionalized peptide toxin aculeine A (Acu-A) from a sponge Axinyssa aculeata. Acu-A is a 45 amino acid-residue peptide with novel post translational modification with long chain polypropanamine attached to the N-terminus. Aculeines were proconvulsant in mice after contral administration. Acu-A was shown to induce calcium influx in cultures HEK293 cells and cultured rat hippocampal cells in an external Ca^<2+> dependent manner suggesting membrane disrupting function of the molecule. Partial amino acid sequence of Acu-A was determined by combination of Edman detradation and MADLDI-TOFMS analysis of the enzyme digests. The whole amino acid sequence for Acu A was deduced from nucleic acid sequence determined by 3' and 5'-RACE agreeing well with the above amino acid sequence where six cysteine residues were arranged like typical cystine knots such as conotoxin. These data suggested that Acu-A was a novel class of polyamine-modified cystine knots.
  • I. Miyake, M. Ohira, A. Nakagawara, R. Sakai, R. Sakai  Oncogene  28-  662  -673  2009/02   [Not refereed] [Not invited]  
    The biological and clinical heterogeneity of neuroblastoma is closely associated with signaling pathways that control cellular characteristics such as proliferation, survival and differentiation. The Shc family of docking proteins is important in these pathways by mediating cellular signaling. In this study, we analysed the expression levels of ShcA and ShcC proteins in 46 neuroblastoma samples and showed that a significantly higher level of ShcC protein is observed in neuroblastomas with poor prognostic factors such as advanced stage and MYCN amplification (P < 0.005), whereas the expression level of ShcA showed no significant association with these factors. Using TNB1 cells that express a high level of ShcC protein, it was demonstrated that knockdown of ShcC by RNAi caused elevation in the phosphorylation of ShcA, which resulted in sustained extracellular signal-regulated kinase activation and neurite outgrowth. The neurites induced by ShcC knockdown expressed several markers of neuronal differentiation suggesting that the expression of ShcC potentially has a function in inhibiting the differentiation of neuroblastoma cells. In addition, marked suppression of in vivo tumorigenicity of TNB1 cells in nude mice was observed by stable knockdown of ShcC protein. These findings indicate that ShcC is a therapeutic target that might induce differentiation in the aggressive type of neuroblastomas. © 2009 Macmillan Publishers Limited All rights reserved.
  • Masamitsu Tanaka, Kazuki Sasaki, Reiko Kamata, Yukari Hoshino, Kazuyoshi Yanagihara, Ryuichi Sakai, Ryuichi Sakai  Molecular and Cellular Biology  29-  402  -413  2009/01   [Not refereed] [Not invited]  
    During the process of tumor progression and clinical treatments, tumor cells are exposed to oxidative stress. Tumor cells are frequently resistant to such stress by producing antiapoptotic signaling, including activation of Src family kinases (SFKs), although the molecular mechanism is not clear. In an attempt to identify the SFK-binding proteins selectively phosphorylated in gastric scirrhous carcinoma, we identified an uncharacterized protein, C9orf10. Here we report that C9orf10 (designated Ossa for oxidative stress-associated Src activator) is a novel RNA-binding protein that guards cancer cells from oxidative stress-induced apoptosis by activation of SFKs. Exposure to oxidative stress such as UV irradiation induces the association of Ossa/C9orf10 with regulatory domains of SFKs, which activates these kinases and causes marked tyrosine phosphorylation of C9orf10 in turn. Tyrosine-phosphorylated Ossa recruits p85 subunits of phosphatidylinositol 3-kinase (PI3-kinase) and behaves as a scaffolding protein for PI3-kinase and SFKs, which activates the Akt-mediated antiapoptotic pathway. On the other hand, the carboxyl terminus of Ossa has a distinct function that directly binds RNAs such as insulin-like growth factor II (IGF-II) mRNA and promotes the extracellular secretion of IGF-II. Our findings indicate that Ossa is a dual-functional protein and might be a novel therapeutic target which modulates the sensitivity of tumors to oxidative stress. Copyright © 2009, American Society for Microbiology. All Right Reserved.
  • 喜田昭子, 神保充, 森本幸生, 酒井隆一, 神谷久男, 三木邦夫  PFシンポジウム要旨集  26th-  96  2009   [Not refereed] [Not invited]
  • Tetsuya Nakamoto, Tetsuya Nakamoto, Tetsuya Nakamoto, Tetsuya Nakamoto, Sachiko Seo, Ryuichi Sakai, Takayuki Kato, Haruo Kutsuna, Mineo Kurokawa, Masaki Noda, Masaki Noda, Nobuyuki Miyasaka, Nobuyuki Miyasaka, Seiichi Kitagawa  Journal of Cellular Biochemistry  105-  121  -128  2008/09   [Not refereed] [Not invited]  
    Crk-associated substrate lymphocyte type (Cas-L) protein, also known as human enhancer of filamentation 1 (Hef1) or neural precursor cell-expressed, developmentally down-regulated gene 9 (Nedd9), belongs to the Cas family of adapter proteins, which are involved in integrin signaling. Previous reports showed that Cas-L is expressed preferentially in lymphocytes and epithelial cells. Cas-L mediates signals from integrins, T-cell receptors, B-cells receptors, and transforming growth factor beta, leading to cell movement and cell division. Here, we report the expression of Cas-L in neutrophils. Cas-L was tyrosine-phosphorylated when human neutrophils were stimulated by fMLP, tumor necrosis factor-alpha (TNF), or lipopolysaccharide. The tyrosine phosphorylation of Cas-L in fMLP- or TNF-stimulated neutrophils was further enhanced by adhesion of the cells to their substrates. Cas-L was found to be localized at focal adhesions in stimulated neutrophils based on immunofluorescence microscopy. These findings suggest that Cas-L is one of the targets of inflammatory cytokines and is also modulated by cell adhesion process in neutrophils. © 2008 Wiley-Liss, Inc.
  • 海野昌喜, 篠原正将, 高山昴一郎, 酒井隆一, 佐々木誠, 齋藤正男  天然有機化合物討論会講演要旨集  50th-  173-178  -178  2008/09   [Not refereed] [Not invited]
  • Takamasa Uekita, Masamitsu Tanaka, Misato Takigahira, Yuri Miyazawa, Yukihiro Nakanishi, Yae Kanai, Kazuyoshi Yanagihara, Ryuichi Sakai, Ryuichi Sakai  American Journal of Pathology  172-  1729  -1739  2008/06   [Not refereed] [Not invited]  
    CUB-domain-containing protein 1 (CDCP1) is a type-I transmembrane protein that is highly expressed in colon, breast, and lung cancers. We recently revealed that CDCP1 is associated with and phosphorylated by Src family kinases and is involved in the regulation of anchorage independence of certain lung cancer cell lines. In this study, we examined whether CDCP1 is involved in the regulation of tumor progression of scirrhous gastric cancer, which is a diffusely infiltrative carcinoma with high invasion potential. Expression and phosphorylation levels of CDCP1 correlated with the invasive potential of scirrhous gastric cancers. Reduction of CDCP1 expression by siRNA suppressed migration, invasion, and anchorage independence without affecting the proliferation of highly invasive scirrhous gastric cancer cells. However, CDCP1 overexpression promoted gastric cancer cell migration with low potential of invasion. Loss of CDCP1 suppressed invasion and dissemination of cancer cells that were orthotopically implanted in the gastric wall of nude mice. Expression and phosphorylation of CDCP1 were also detected in cancer cells of surgically resected tissues of human scirrhous gastric cancer by immunohistochemical analysis. Our results suggest that CDCP1 promotes invasion and peritoneal dissemination of cancer cells through the regulation of cell migration and anchorage independence. Therefore, it is both a potential prognostic and therapeutic target in certain types of gastrointestinal cancers, and suppression of its phosphorylation might be a useful strategy for modulating cancer metastasis. Copyright © American Society for Investigative Pathology.
  • Lin Jia, Takamasa Uekita, Ryuichi Sakai, Ryuichi Sakai  Molecular Cancer Research  6-  654  -662  2008/04   [Not refereed] [Not invited]  
    Cortactin is frequently overexpressed in cancer cells, and changes of the levels of its tyrosine phosphorylation have been observed in several cancer cells. However, how the expression level and phosphorylation state of cortactin would influence the ultimate cellular function ofcancer cells is unknown. In this study, we analyzed the role of cortactin in gastric and breast cancer cell lines using RNA interference technique and found that knockdown of cortactin inhibited cell migration in a subset ofgastric cancer cells with a lower level of its tyrosine phosphorylation, whereas it greatly enhanced cell migration and increased tyrosine phosphorylation of p130Cas in other subsets of cells with hyperphosphorylated cortactin. Consistent results were obtained when hyperphosphorylation of cortactin was induced in MCF7 breast cancer cells by expressing Fyn tyrosine kinase. Additionally, immunostaining analysis showed that knockdown of hyperphosphorylated cortactin resulted in the recruitment of p130Cas to focal adhesions. These results suggest that cortactin hyperphosphorylation suppresses cell migration possibly through the inhibition of membrane localization and tyrosine phosphorylation of p130Cas. Copyright © 2008 American Association for Cancer Research.
  • 町田平, 神保充, 酒井隆一, 神谷久男  日本水産学会大会講演要旨集  2008-  65  2008/03   [Not refereed] [Not invited]
  • 局興一, 青木邦衛, 及川雅人, 酒井隆一, 島本啓子, 佐々木誠  日本化学会講演予稿集  88th-  (2)  1041  2008/03   [Not refereed] [Not invited]
  • Tatsuya Tazaki, Tatsuya Tazaki, Kazuko Miyazaki, Eiso Hiyama, Tetsuya Nakamoto, Ryuichi Sakai, Norimasa Yamasaki, Zen ichiro Honda, Masaki Noda, Nobuyuki Miyasaka, Taijiro Sueda, Hiroaki Honda  Genes to Cells  13-  145  -157  2008/02   [Not refereed] [Not invited]  
    p130Cas (Cas, Crk-associated s ubstrate) is an adaptor molecule composed of a Src homology 3 (SH3) domain, a substrate domain (SD) and a Src binding domain (SBD). The SH3 domain of Cas associates with focal adhesion kinase (FAK), but its role in cellular function has not fully been understood. To address this issue, we established and analyzed primary fibroblasts derived from mice expressing a truncated Cas lacking exon 2, which encodes the SH3 domain (Cas Δexon 2). In comparison to wild-type cells, Cas exon 2 Δ/Δ cells showed reduced motility, which could be due to impaired tyrosine-phosphorylation of FAK and Cas, reduced FAK/Cas/Src/CrkII binding, and also impaired localization of Cas Δexon 2 to focal adhesions on fibronectin. In addition, to analyze downstream signaling pathways regulated by Cas exon 2, we performed microarray analyses. Interestingly, we found that a deficiency of Cas exon 2 up-regulated expression of CXC Chemokine Receptor-4 and CC Chemokine Receptor-5, which may be regulated by IκBα phosphorylation. These results indicate that the SH3-encoding exon of Cas participates in cell motility, tyrosine-phosphorylation of FAK and Cas, FAK/Cas/Src/CrkII complex formation, recruitment of Cas to focal adhesions and regulation of cell motility-associated gene expression in primary fibroblasts. Journal compilation © 2008 by the Molecular Biology Society of Japan/Blackwell Publishing Ltd.
  • 喜田昭子, 神保充, 森本幸生, 酒井隆一, 神谷久男, 三木邦夫  生化学  4P-0107  2008   [Not refereed] [Not invited]
  • Unno Masaki, Shinohara Masanobu, Takayama Koichiro, Sakai Ryuichi, Sasaki Makoto, Ikeda-Saito Masao  天然有機化合物討論会講演要旨集  0-  (50)  173  -178  2008/09   [Not refereed] [Not invited]  
    Dysiherbaine (DH) and its congener neodysiherbaine A (NDH) are naturally occurring excitatory amino acids with high-affinity and subunit-selectivity for kainate type ionotropic glutamate receptors, especially GluR5 and GluR6 subunits. To elucidate why DH and NDH bind selectively to GluR5, we have determined the crystal structures of human GluR5 ligand-binding core in complexes with DH and NDH, in addition to the glutamate-complex. DH and NDH form unique hydrogen-bonding and hydrophobic interactions with the amino acid residues in the binding-cleft by excluding the water molecules, which med...
  • 生駒実, 及川雅人, 佐々木誠, 酒井隆一  有機合成シンポジウム講演要旨集  93rd-  65-68  -68  2008   [Not refereed] [Not invited]
  • Takamasa Uekita, Lin Jia, Mako Narisawa-Saito, Jun Yokota, Tohru Kiyono, Ryuichi Sakai, Ryuichi Sakai  Molecular and Cellular Biology  27-  7649  -7660  2007/11   [Not refereed] [Not invited]  
    Malignant tumor cells frequently achieve resistance to anoikis, a form of apoptosis induced by detachment from the basement membrane, which results in the anchorage-independent growth of these cells. Although the involvement of Src family kinases (SFKs) in this alteration has been reported, little is known about the signaling pathways involved in the regulation of anoikis under the control of SFKs. In this study, we identified a membrane protein, CUB-domain-containing protein 1 (CDCP1), as an SFK-binding phosphoprotein associated with the anchorage independence of human lung adenocarcinoma. Using RNA interference suppression and overexpression of CDCP1 mutants in lung cancer cells, we found that tyrosine-phosphorylated CDCP1 is required to overcome anoikis in lung cancer cells. An apoptosis-related molecule, protein kinase Cδ, was found to be phosphorylated by the CDCP1-SFK complex and was essential for anoikis resistance downstream of CDCP1. Loss of CDCP1 also inhibited the metastatic potential of the A549 cells in vivo. Our findings indicate that CDCP1 is a novel target for treating cancer-specific disorders, such as metastasis, by regulating anoikis in lung adenocarcinoma. Copyright © 2007, American Society for Microbiology. All Rights Reserved.
  • 酒井隆一, 松永智子, 神保充, 神谷久男  日本水産学会大会講演要旨集  2007-  117  2007/03   [Not refereed] [Not invited]
  • 神保充, 本橋詳子, 酒井隆一, 神谷久男  日本動物学会大会要旨集  78th-  41  2007/08   [Not refereed] [Not invited]
  • 局興一, 秋山伸之, 青木邦衛, 及川雅人, 酒井隆一, 島本啓子, 佐々木誠  天然有機化合物討論会講演要旨集  49th-  691-696  -696  2007/08   [Not refereed] [Not invited]
  • 秋山伸之, 庄司宗生, 酒井隆一, SWANSON G.T., 及川雅人, 佐々木誠  化学系学協会東北大会プログラムおよび講演予稿集  2006-  105  2006/09   [Not refereed] [Not invited]
  • 神保充, 安部聡一郎, 山下洋, 石明大, 母家大樹, 岩尾研二, 小池一彦, 酒井隆一, 神谷久男  日本水産学会大会講演要旨集  2007-  275  2007/03   [Not refereed] [Not invited]
  • Tsubone Koichi, Akiyama Nobuyuki, Aoki Kunimori, Oikawa Masato, Sakai Ryuichi, Shimamoto Keiko, Sasaki Makoto  天然有機化合物討論会講演要旨集  0-  (49)  691  -696  2007/08   [Not refereed] [Not invited]  
    Dysiherbaine (DH, 1) and its congener neodysiherbaine A (2), isolated from the Micronesian marine sponge, Dysidea herbacea, are remarkable excitatory amino acids with potent convulsant activity. DH activates the AMPA and kainate classes of ionotropic glutamate receptors, with a higher affinity for the latter. Furthermore, it has been revealed that DH had extremely high affinity for GluR5 and GluR6 kainate receptor subunits. Due to these intriguing pharmacological properties to kainite receptors, DH and its designed analogues are anticipated to serve as useful tools for understanding the com...
  • 及川雅人, 生駒実, 佐々木誠, 酒井隆一  Abstr Conf Comb Chem Jpn  27th-  88-91  2008   [Not refereed] [Not invited]
  • 越川阿紗美, 酒井隆一, 小池一彦, 山下洋, 神保充, 神谷久男  マリンバイオテクノロジー学会大会講演要旨集  9th-  108  2006/05   [Not refereed] [Not invited]
  • 秋山伸之, 局興一, 青木邦衛, 庄司宗生, 酒井隆一, 及川雅人, 佐々木誠  日本化学会講演予稿集  87th-  (2)  1187  2007/03   [Not refereed] [Not invited]
  • Makoto Sasaki, Nobuyuki Akiyama, Koichi Tsubone, Muneo Shoji, Masato Oikawa, Ryuichi Sakai  Tetrahedron Letters  48-  5697  -5700  2007/08   [Not refereed] [Not invited]  
    An efficient total synthesis of dysiherbaine, a potent and subtype-selective agonist for ionotropic glutamate receptors, has been achieved. An advanced key intermediate in the previous synthesis of neodysiherbaine A and its analogues was selected as the starting point, and cis-oriented amino alcohol functionality on the tetrahydropyran ring was installed by using an intramolecular S N 2 cyclization of N-Boc-protected amino alcohol. The amino acid appendage was constructed by catalytic asymmetric hydrogenation of enamide ester. © 2007 Elsevier Ltd. All rights reserved.
  • 木村敦子, 酒井隆一, 吉田和史, 小池一彦, 小池香苗, 神保充, 神谷久男  マリンバイオテクノロジー学会大会講演要旨集  9th-  109  2006/05   [Not refereed] [Not invited]
  • 生駒実, 及川雅人, 酒井隆一, 佐々木誠  日本化学会講演予稿集  87th-  (2)  1187  2007/03   [Not refereed] [Not invited]
  • 松永智子, 酒井隆一, 神保充, 神谷久男  マリンバイオテクノロジー学会大会講演要旨集  9th-  109  2006/05   [Not refereed] [Not invited]
  • 神保充, 土橋一貴, 巳城摩倫, 三宅裕志, 吉田尊雄, 佐藤孝子, 丸山正, 酒井隆一, 神谷久男  しんかいシンポジウム予稿集  23rd-  58  2007/03   [Not refereed] [Not invited]
  • 神保充, 佐藤心, 吉田尊雄, 丸山正, 三宅裕志, 酒井隆一, 神谷久男  生化学  4P-0032  2007   [Not refereed] [Not invited]
  • 松永智子, 酒井隆一, 神保充, 神谷久男  日本水産学会大会講演要旨集  2006-  184  2006/03   [Not refereed] [Not invited]
  • 篠原正将, 海野昌喜, 照屋健太, 酒井隆一, 堂浦克美, 佐々木誠, 齋藤正男  生化学  1P-0039  2007   [Not refereed] [Not invited]
  • Masamitsu Tanaka, Reiko Kamata, Misato Takigahira, Kazuyoshi Yanagihara, Ryuichi Sakai, Ryuichi Sakai  American Journal of Pathology  171-  68  -78  2007/07   [Not refereed] [Not invited]  
    Interaction of the Eph family of receptor protein tyrosine kinase and its ligand ephrin family induces bidirectional signaling via cell-cell contacts. High expression of B-type ephrin is frequently found in various cancer cells, and their expression levels are associated with high invasion of tumors and poor prognosis. However, whether ephrin-B1 actually promotes invasion of cancer cells in vivo has not been shown. We investigated the involvement of ephrin-B1 in regulating the invasiveness of scirrhous gastric cancer, which is a diffusely infiltrative carcinoma with high invasion potential. Reduction of ephrin-B1 expression by short interfering RNA or overexpression of phosphorylation- defective mutant suppressed migration and invasion of scirrhous gastric cancer cells in vitro without affecting tumor cell proliferation and apoptosis. Blocking of tyrosine phosphorylation of ephrin-B1 attenuates not only dissemination of cancer cells injected intraperitoneally but also local invasion and dissemination of orthotopically implanted cancer cells in the gastric wall of nude mice. Furthermore, blocking of ephrin-B1 phosphorylation attenuated the activation of Rac1 GTPase in these invasive gastric cancer cells. Our results suggest that tyrosine phosphorylation of ephrin-B1 promotes invasion of cancer cells in vivo and is a potential therapeutic target in some types of gastrointestinal cancers. Copyright © American Society for Investigative Pathology.
  • 神保充, 野中敦司, 井上知美, 三宅裕志, 佐藤孝子, 丸山正, 酒井隆一, 神谷久男  日本水産学会大会講演要旨集  2006-  186  2006/03   [Not refereed] [Not invited]
  • H. Kamiya, R. Sakai, M. Jimbo  Progress in molecular and subcellular biology  43-  215  -239  2006/12   [Not refereed] [Not invited]  
    Sea hares, belonging to the order Opisthobranchia, subclass Gastropoda, are mollusks that have attracted many researchers who are interested in the chemical defense mechanisms of these soft and "shell-less" snails. Numbers of small molecules of dietary origin have been isolated from sea hares and some have ecologically relevant activities, such as fish deterrent activity or toxicity. Recently, however, greater attention has been paid to biomedically interesting sea hare isolates such as dolastatins, a series of antitumor peptide/macrolides isolated from Dolabella auricularia. Another series of bioactive peptide/macrolides, as represented by aplyronines, have been isolated from sea hares in Japanese waters. Although earlier studies indicated the potent antitumor activity of aplyronines, their clinical development has never been conducted because of the minute amount of compound available from the natural source. Recent synthetic studies, however, have made it possible to prepare these compounds and analogs for a structure-activity relationship study, and started to uncover their unique action mechanism towards their putative targets, microfilaments. Here, recent findings of small antitumor molecules isolated from Japanese sea hares are reviewed. Sea hares are also known to produce cytotoxic and antimicrobial proteins. In contrast to the small molecules of dietary origin, proteins are the genetic products of sea hares and they are likely to have some primary physiological functions in addition to ecological roles in the sea hare. Based on the biochemical properties and phylogenetic analysis of these proteins, we propose that they belong to one family of molecule, the "Aplysianin A family," although their molecular weights are apparently divided into two groups. Interestingly, the active principles in Aplysia species and Dolabella auricularia were shown to be L-amino acid oxidase (LAAO), a flavin enzyme that oxidizes an alpha-amino group of the substrate with molecular oxygen and liberates hydrogen peroxide, with a sequence similar to other known LAAOs, including snake venom. Possible antibacterial activity and cytotoxic activity mechanisms of these proteins are also discussed.
  • Masamitsu Tanaka, Kazuki Sasaki, Kazuki Sasaki, Reiko Kamata, Ryuichi Sakai  Journal of Cell Science  120-  2179  -2189  2007/07   [Not refereed] [Not invited]  
    Interaction of the Eph family of receptor protein tyrosine kinases and their ligands, ephrin family members, induces bi-directional signaling via cell-cell contacts. High expression of B-type ephrin is associated with high invasion potential of tumors, however, the mechanism by which ephrin-B promotes cancer cell invasion is poorly understood. We show that interaction of ephrin-B1 with the Eph receptor B2 (EphB2) significantly enhances processing of the extracellular domain of ephrin-B1, which is regulated by the C-terminus. Matrix metalloproteinase-8 (MMP-8) is the key protease that cleaves ephrin-B1, and the C-terminus of ephrin-B1 regulates activation of the extracellular release of MMP-8 without requirement of de novo protein synthesis. One possible mechanism by which ephrin-B1 regulates the exocytosis of MMP-8 is the activation of Arf1 GTPase, a critical regulator of membrane trafficking. In support of this hypothesis, activation of ephrin-B1 increased GTP-bound Arf1, and the secretion of MMP-8 was reduced by expression of a dominant-negative mutant of Arf1. Expression of ephrin-B1 promoted the invasion of cancer cells in vivo, which required the C-terminus of ephrin-B1. Our results suggest a novel function of the C-terminus of ephrin-B1 in activating MMP-8 secretion, which promotes the invasion of cancer cells.
  • 本橋詳子, 神保充, 酒井隆一, 神谷久男  日本水産学会大会講演要旨集  2006-  185  2006/03   [Not refereed] [Not invited]
  • 酒井隆一  マリンバイオテクノロジー学会大会講演要旨集  10th-  63  2007/05   [Not refereed] [Not invited]
  • 神保充, 佐藤心, 酒井隆一, 佐藤孝子, 丸山正, 三宅裕志, 神谷久男  日本水産学会大会講演要旨集  2006-  185  2006/03   [Not refereed] [Not invited]
  • Ryuichi Sakai, Geoffrey T. Swanson, Makoto Sasaki, Keiko Shimamoto, Hisao Kamiya  Central Nervous System Agents in Medicinal Chemistry  6-  83  -108  2006/10   [Not refereed] [Not invited]  
    The molecular diversity of marine secondary metabolites has been recognized for a number of years, and classic marine-derived excitatory amino acids (EAAs) such as kainic and domoic acid have been indispensable tools in neurobiological research. The recent discovery of the sponge-derived EAA dysiherbaine (DH, 1), a novel di-amino di-acid glutamate analogue with potent convulsant activity, underscores the relatively untapped potential of marine organisms to serve as sources of EAAs with unique structures and activities [1]. DH (1) has a number of pharmacological actions but binds with highest affinity to kainate receptors, a sub-family of non-N-methyl-D-aspartate (non-NMDA)-type GluRs, which are also the molecular targets of other potent EAA convulsants like domoic acid. The high affinity and selectivity of 1 towards certain kainate receptor subtypes made it a useful tool for exploring aspects of the biophysical function of these ion channels [2] . In combination with chemical syntheses and neurophysiological techniques, we have shown that 1 and its structural analogues can serve as unique biophysical and physiological probes of GluR function [3]. Current studies have begun to elucidate the critical moieties on 1 that confer activity and selectivity. We anticipate that 1 will serve as a useful template upon which to build molecules with novel pharmacological actions and potential therapeutic applications. In this review, we describe the chemical, pharmacological and behavioral profile of 1 and closely related analogues, with a particular emphasis on their actions on iGluRs, a family of ligand-gated ion channel critical for excitatory neurotransmission in the mammalian brain. © 2006 Bentham Science Publishers Ltd.
  • 酒井隆一, 中村隆典, 西野泰斗, 山本正雄, 宮村淳史, 宮本久恵, 石綿紀久, 小松則夫, 神谷久男, 水流添暢智  日本水産学会大会講演要旨集  2006-  184  2006/03   [Not refereed] [Not invited]
  • SHOJI MUNEO, AKIYAMA NOBUYUKI, LASH L. L., SANDERS J. M., SWANSON G. T., SAKAI RYUICHI, SHIMAMOTO KEIKO, OIKAWA MASATO, SASAKI MAKOTO  日本化学会講演予稿集  86th-  (2)  1356  2006/03   [Not refereed] [Not invited]
  • Yasuhiro Sawada, Masako Tamada, Benjamin J. Dubin-Thaler, Oksana Cherniavskaya, Ryuichi Sakai, Sakae Tanaka, Michael P. Sheetz  Cell  127-  1015  -1026  2006/12   [Not refereed] [Not invited]  
    How physical force is sensed by cells and transduced into cellular signaling pathways is poorly understood. Previously, we showed that tyrosine phosphorylation of p130Cas (Cas) in a cytoskeletal complex is involved in force-dependent activation of the small GTPase Rap1. Here, we mechanically extended bacterially expressed Cas substrate domain protein (CasSD) in vitro and found a remarkable enhancement of phosphorylation by Src family kinases with no apparent change in kinase activity. Using an antibody that recognized extended CasSD in vitro, we observed Cas extension in intact cells in the peripheral regions of spreading cells, where higher traction forces are expected and where phosphorylated Cas was detected, suggesting that the in vitro extension and phosphorylation of CasSD are relevant to physiological force transduction. Thus, we propose that Cas acts as a primary force sensor, transducing force into mechanical extension and thereby priming phosphorylation and activation of downstream signaling. © 2006 Elsevier Inc. All rights reserved.
  • SHOJI MUNEO, TSUBONE KOICHI, SAKAI RYUICHI, SHIMAMOTO KEIKO, OIKAWA MASATO, SASAKI MAKOTO  日本化学会講演予稿集  86th-  (2)  1357  2006/03   [Not refereed] [Not invited]
  • 木村敦子, 酒井隆一, 吉田和史, 小池一彦, 小池香苗, 小檜山篤志, 神保充, 神谷久男  日本水産学会大会講演要旨集  2007-  117  2007/03   [Not refereed] [Not invited]
  • 松永智子, 酒井隆一, 神保充, 神谷久男  天然有機化合物討論会講演要旨集  48th-  307-312  -312  2006/09   [Not refereed] [Not invited]
  • 松永智子, 酒井隆一, 神保充, 神谷久男  日本水産学会大会講演要旨集  2007-  117  2007/03   [Not refereed] [Not invited]
  • Jinhong Huang, Ryuichi Sakai, Teiichi Furuichi  Molecular Biology of the Cell  17-  3187  -3196  2006/07   [Not refereed] [Not invited]  
    Crk-associated substrate (Cas) is a tyrosine-phosphorylated docking protein that is indispensable for the regulation of the actin cytoskeletal organization and cell migration in fibroblasts. The function of Cas in neurons, however, is poorly understood. Here we report that Cas is dominantly enriched in the brain, especially the cerebellum, of postnatal mice. During cerebellar development, Cas is highly tyrosine phosphorylated and is concentrated in the neurites and growth cones of granule cells. Cas coimmunoprecipitates with Src family protein tyrosine kinases, Crk, and cell adhesion molecules and colocalizes with these proteins in granule cells. The axon extension of granule cells is inhibited by either RNA interference knockdown of Cas or overexpression of the Cas mutant lacking the YDxP motifs, which are tyrosine phosphorylated and thereby interact with Crk. These findings demonstrate that Cas acts as a key scaffold that links the proteins associated with tyrosine phosphorylation signaling pathways to the granule cell axon elongation. © 2006 by The American Society for Cell Biology.
  • 庄司宗生, 塩原薫, 及川雅人, 酒井隆一, SWAMSON G. T., SANDERS J. A., 島本啓子, 佐々木誠  天然有機化合物討論会講演要旨集  47th-  49-54  -54  2005/09   [Not refereed] [Not invited]
  • Matsunaga Satoko, Sakai Ryuichi, Jimbo Mitsuru, Kamiya Hisao  天然有機化合物討論会講演要旨集  0-  (48)  307  -312  2006/09   [Not refereed] [Not invited]  
    Long chain polyamines (LCPA), which have been known exclusively in silica wall of diatoms in nature, are thought to play a central role in diatom's silica deposition. In the present study, however, we identified LCPA for the first time from the marine sponge Axinyssa aculeata and named LCPA-Aa. The LCPA-Aa was obtained as a mixture of oligo-propaneamine sulfates of 5 to 15 repeating units (ru). It has been reported that LCPA of diatoms mediate precipitation of silica in a multivalent anion-dependent manner, in that the multivalent anions are important in facilitating the formation of large ...
  • 神保充, 佐藤心, 酒井隆一, 佐藤孝子, 丸山正, 三宅裕志, 神谷久男  マリンバイオテクノロジー学会大会講演要旨集  9th-  101  2006/05   [Not refereed] [Not invited]
  • 木村敦子, 酒井隆一, 吉田和史, 小池香苗, 小池一彦, 神保充, 神谷久男  日本水産学会大会講演要旨集  2005-  123  2005/04   [Not refereed] [Not invited]
  • 酒井隆一, 平田泰子, 小池一彦, 神谷久男  日本水産学会大会講演要旨集  2005-  116  2005/04   [Not refereed] [Not invited]
  • 神保充, 尾野壮一, 酒井隆一, 神谷久男  日本水産学会大会講演要旨集  2005-  119  2005/04   [Not refereed] [Not invited]
  • 本橋詳子, 宮根敦子, 神保充, 酒井隆一, 神谷久男  日本水産学会大会講演要旨集  2005-  118  2005/04   [Not refereed] [Not invited]
  • SHOJI MUNEO, SHIOHARA KAORU, OIKAWA MASATO, SASAKI MAKOTO, SAKAI RYUICHI  日本化学会講演予稿集  85th-  (2)  854  2005/03   [Not refereed] [Not invited]
  • Masamitsu Tanaka, Reiko Kamata, Ryuichi Sakai  Journal of Biological Chemistry  280-  42375  -42382  2005/12   [Not refereed] [Not invited]  
    Eph receptors and ephrin ligands are widely expressed in epithelial cells and mediate cell-cell interaction. EphA2 is expressed in various cancer tissues and cell lines. Although the mechanism of action of EphA2 is unknown, its expression correlates with progression of the malignant phenotype of cancerous tissues. Here, we have shown that EphA2 modulates the localization and function of claudin-4, a constituent of tight junctions. EphA2 associates with claudin-4 via their extracellular domains. This association, in turn, leads to phosphorylation of the cytoplasmic carboxyl terminus of claudin-4 at Tyr-208. The tyrosine phosphorylation of claudin-4 attenuates association of claudin-4 with ZO-1, decreasing integration of claudin-4 into sites of cell-cell contact and enhancing paracellular permeability. These results indicate that EphA2 moderates the function of tight junctions via phosphorylation of claudin-4. © 2005 by The American Society for Biochemistry and Molecular Biology, Inc.
  • 佐藤心, 宮尾佳子, 神保充, 酒井隆一, 神谷久男, 佐藤孝子, 丸山正  日本水産学会北海道支部大会講演要旨集  2005-  82  2005   [Not refereed] [Not invited]
  • Muneo Shoji, Kaoru Shiohara, Masato Oikawa, Ryuichi Sakai, Makoto Sasaki  Tetrahedron Letters  46-  5559  -5562  2005/08   [Not refereed] [Not invited]  
    Synthesis of dysiherbaine analogue 4, which corresponds to 8,9-epi-neodysiherbaine A, is described. The synthesis features a concise route to the bicyclic ether skeleton through stereoselective C-glycosylation to set the C 6 stereocenter and 5-exo ring-closure to form the tetrahydrofuran ring. The results of preliminary biological studies of 4 are also provided. © 2005 Elsevier Ltd. All rights reserved.
  • Masamitsu Tanaka, Reiko Kamata, Ryuichi Sakai, Ryuichi Sakai  EMBO Journal  24-  3700  -3711  2005/11   [Not refereed] [Not invited]  
    The interaction of the Eph family of receptor protein tyrosine kinase and its ligand ephrin family induces bidirectional signaling via the cell-cell contacts. Although most previous studies have focused on the function of Eph-ephrin pathways in the neural system and endothelial cells, this process also occurs in epithelial and cancer cells, of which the biological involvement is poorly understood. We show that ephrin-B1 creates an in vivo complex with adjacent claudin1 or claudin4 via the extracellular domains of these proteins. The cytoplasmic domain of ephrin-B1 was phosphorylated on tyrosine residues upon the formation of cell-cell contacts, possibly recognizing an intercellular adhesion of claudins. Phosphorylation of ephrin-B1 induced by claudins was abolished by the treatment with 4-amino-5-(4-chlorophenyl)-7-(t-butyl) pyrazolo[3,4-d]pyrimidine, an inhibitor of the Src family kinases. Moreover, overexpression of ephrin-B1 triggered consequent change in the level of cell-cell adhesion depending on its phosphorylation. These results suggest that ephrin-B1 mediated the cell-cell adhesion of epithelial and cancer cells via a novel Eph receptor-independent mechanism. © 2005 European Molecular Biology Organization | All Rights Reserved.
  • Sachiko Seo, Takashi Asai, Toshiki Saito, Takahiro Suzuki, Yasuyuki Morishita, Tetsuya Nakamoto, Motoshi Ichikawa, Go Yamamoto, Masahito Kawazu, Tetsuya Yamagata, Ryuichi Sakai, Kinuko Mitani, Seishi Ogawa, Mineo Kurokawa, Mineo Kurokawa, Shigeru Chiba, Hisamaru Hirai  Journal of Immunology  175-  3492  -3501  2005/09   [Not refereed] [Not invited]  
    The lymphocyte-specific Cas family protein Cas-L (Crk-associated substrate lymphocyte type) has been implicated to function in lymphocyte movement, mediated mainly by integrin signaling. However, its physiological role is poorly understood. In this study we analyzed the function of Cas-L in lymphocytes using gene-targeted mice. The mutant mice showed a deficit of marginal zone B (MZB) cells and a decrease of cell number in secondary lymphoid organs. An insufficient chemotactic response and perturbed cell adhesion were observed in Cas-L-deficient lymphocytes, suggesting that the aberrant localization was responsible for the deficit of MZB cells. Moreover, we found that lymphocyte trafficking was altered in Cas-L-deficient mice, which gave a potential reason for contraction of secondary lymphoid tissues. Thus, Cas-L affects homeostasis of MZB cells and peripheral lymphoid organs, which is considered to be relevant to impaired lymphocyte migration and adhesion. Copyright © 2005 by The American Association of Immunologists, Inc.
  • 神保充, 酒井隆一, 神谷久男, 太田英司, 村本光二  日本水産学会大会講演要旨集  2004-  198  2004/03   [Not refereed] [Not invited]
  • 神保充, 江頭浩司, 高橋正興, 得能大輔, 酒井隆一, 神谷久男  日本水産学会大会講演要旨集  2004-  199  2004/03   [Not refereed] [Not invited]
  • Kotaro Azuma, Kotaro Azuma, Masamitsu Tanaka, Takamasa Uekita, Satoshi Inoue, Jun Yokota, Yasuyoshi Ouchi, Ryuichi Sakai  Oncogene  24-  4754  -4764  2005/07   [Not refereed] [Not invited]  
    To acquire information on signal alteration corresponding to the changes in metastatic potential, we analysed protein tyrosine phosphorylation of low- and high-metastatic human osteosarcoma HuO9 sublines, which were recently established as the first metastatic model of human osteosarcoma. Tyrosine phosphorylation of proteins around 60, 70, and 120-130 kDa was enhanced in high-metastatic sublines. Among these proteins, the protein around 70 kDa, which was most remarkably phosphorylated, was identified as paxillin, a scaffold protein in integrin signaling. Activity of Src family kinase correlated well with metastatic potential, and a Src family kinase inhibitor, PP2, not only abolished tyrosine phosphorylation of paxillin but also impaired the motility of high-metastatic sublines. The expression of paxillin was also elevated in high-metastatic sublines, and knocking down of paxillin expression by RNAi method resulted in attenuated motility of high-metastatic cells. We also demonstrated that the phosphorylated form of paxillin is essential for the migration-promoting effect in human osteosarcoma. These findings suggest that enhanced activity of Src family kinases and overexpression of paxillin synergistically contribute to the high metastatic potential of human osteosarcoma through the hyperphosphorylation of paxillin. © 2005 Nature Publishing Group. All rights reserved.
  • Yuko Osajima-Hakomori, Yuko Osajima-Hakomori, Yuko Osajima-Hakomori, Izumi Miyake, Izumi Miyake, Miki Ohira, Akira Nakagawara, Atsuko Nakagawa, Ryuichi Sakai, Ryuichi Sakai  American Journal of Pathology  167-  213  -222  2005/07   [Not refereed] [Not invited]  
    Anaplastic lymphoma kinase (ALK) is a tyrosine kinase receptor originally identified as part of the chimeric nucleophosmin-ALK protein in the t(2;5) chromosomal rearrangement associated with anaplastic large cell lymphoma. We recently demonstrated that the ALK kinase is constitutively activated by gene amplification at the ALK locus in several neuroblastoma cell lines. Forming a stable complex with hyperphosphorylated ShcC, activated ALK modifies the responsiveness of the mitogen-activated protein kinase pathway to growth factors. In the present study, the biological role of activated ALK was examined by suppressing the expression of ALK kinase in neuroblastoma cell lines using an RNA interference technique. The suppression of activated ALK in neuroblastoma cells by RNA interference significantly reduced the phosphorylation of ShcC, mitogen-activated protein kinases, and Akt, inducing rapid apoptosis in the cells. By immunohistochemical analysis, the cytoplasmic expression of ALK was detected in most of the samples of neuroblastoma tissues regardless of the stage of the tumor, whereas significant amplification of ALK was observed in only 1 of 85 cases of human neuroblast oma samples. These data demonstrate the limited frequency of ALK activation in the real progression of neuroblastoma. Copyright © American Society for Investigative Pathology.
  • Izumi Miyake, Izumi Miyake, Yuko Hakomori, Yoko Misu, Hisaya Nakadate, Nobuo Matsuura, Michiie Sakamoto, Ryuichi Sakai  Oncogene  24-  3206  -3215  2005/04   [Not refereed] [Not invited]  
    ShcC is a family member of the Shc docking proteins that possess two different phosphotyrosine-binding motifs and conduct signals as Grb2-binding substrates of various receptor tyrosine kinases. We have recently shown that some neuroblastoma cell lines, such as NB-39-nu cells, express a protein complex of hyperphosphorylated ShcC and anaplastic lymphoma kinase (ALK), which is self-activated by gene amplification. Here, we demonstrate that the expression of a mutant ShcC lacking Grb2-binding sites, 3YF-ShcC, significantly impaired the survival, differentiation and motility of NB-39-nu cells by blocking the ERK and Akt pathways. On the other hand, cells overexpressing ShcC or 3YF-ShcC, but not a mutant ShcC that lacks SH2, showed decreased anchorage independency and in vivo tumorigenicity, suggesting a novel ShcC-specific suppressive effect through its SH2 domain on cell transformation. Notably, overexpression of ShcC suppressed the sustained phosphorylation of Src family kinase after cell detachment, which might be independent of phosphorylation of Grb2-binding site. It was indicated that the Src/Fyn-Cas pathway is modulated as a target of these suppressive effects by ShcC. Reciprocal change of ShcC expression and phosphorylation observed in malignant neuroblastoma cell lines might be explained by these phosphotyrosine-dependent and -independent functions of ShcC. © 2005 Nature Publishing Group All rights reserved.
  • 佐藤心, 神保充, 酒井隆一, 神谷久男  日本水産学会大会講演要旨集  2004-  196  2004/03   [Not refereed] [Not invited]
  • SAKAI R.  J Am Chem Soc  119-  (18)  4112  -4116  1997/05   [Not refereed] [Not invited]  
    A new amino acid, dysiherbaine (1), was isolated from a Micronesian sponge Dysidea herbacea. The structure was determined by using FABMS, ESIMS, FABMS/CID/MS, and one- and two-dimensional NMR experiments of 1 and its dimethyl derivative 3 to be a novel diamino dicarboxylic acid, which consisted of a cisfused hexahydrofuro[3,2-b]pyran ring substituted with a 3- [2-aminopropanoic acid] side chain. The relative configuration of the bicyclic portion of 1 was determined by 3 J(H.H.) analysis and difference NOE experiments, and that of the acyclic side chain was assigned by additional 2 , 3 J(C,H) analysis, measured by hetero half-filtered TOCSY (HETLOC) and phase sensitive HMBC experiments. Systemic administration of 1 induced neurotoxic symptoms in mice which were reminiscent of neuroexcitatory amino acids such as domoic acid. Dysiherbaine inhibited bindings of [ 3 H]-kainic acid (KA) and [ 3 H]-1-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), but not [ 3 H]-CGS-19755, an N-methyl-D-asparatic acid (NMDA) receptor antagonist, on rat brain synaptic membranes, suggesting that 1 is a selective agonist of non-NMDA type glutamate receptors in the central nervous system.
  • Shoji Muneo, Shiohara Kaoru, Oikawa Masato, Sakai Ryuichi, Sanders James M., Swanson Geoffrey T., Shimamoto Keiko, Sasaki Makoto  天然有機化合物討論会講演要旨集  0-  (47)  49  -54  2005/09   [Not refereed] [Not invited]  
    Dysiherbaine (DH, 1) and its congener neodysiherbaine A (2), isolated from the Micronesian marine sponge, Dysidea herbacea, are novel excitatory amino acids with potent convulsant activity. DH activates non-NMDA type glutamate receptors [AMPA and kainic acid (KA) receptors] with considerable preference over KA receptors. Moreover, it has been shown that DH binds to the GluR5 and GluR6 KA receptor subunits with high affinity. Due to these intriguing pharmacological properties to KA receptors, DH and its designed analogues are anticipated to serve as useful tools for understanding the structu...
  • Sakai Ryuichi, Swanson Geffery T, Shimammoto Keiko, Kamiya Hisao  Proceedings of Annual Meeting of the Physiological Society of Japan  2004-  (0)  S13  -S13  2004   [Not refereed] [Not invited]  
    Dysiherbaine (DH) is a novel marine sponge-derived amino acid and is highly epileptogenic in mice. Administration of DH induced long lasting convulsive behaviors with ED50 values of 13 pmol/mouse, i.c.v., and 0.97 mg/kg, i.p. which is 5-7 time more potent than that of domoic acid. In rat brain synaptic membranes DH displaced binding of [3H]kainic acid (KA) and [3H]AMPA with Ki values of 26 and 153 nM, respectively. In contrast, DH did not displace the NMDA receptor ligand [3H] CGS-19755. DH also displaced [3H]KA from the recombinant GluR5 and GluR6 at Ki value of each 0.74 and 1.2 nM, respectively. In whole-cell voltage clamp recordings from cultured rat hippocampal neurons DH evoked inward currents from both AMPA and KA receptors with EC50 values of 9.7 μM and 210 nM, respectively. Additionally DH activated mGlu5 but not mGluR1. In the heteromerically expressed KA receptors, GluR5-KA2, in HEK 293 cells DH evoked desensitizing inward current. However, the inward current arose again after removal of DH. Application of glutamate to this "activated" receptor can further elicit the desensitizing inward current. Surprisingly, non-desensitizing inward current was gated by CNQX, a classically defined antagonist. These results demonstrated that DH can activate only high affinity GluR5 site in the heteromerically assembled GluR5/KA2, and that for the first time the low affinity subunit, KA2, can gate channel currents individually upon application of the agonists in quite unexpected ways. [Jpn J Physiol 54 Suppl:S13 (2004)]
  • Mitsuru Jimbo, Fumie Nakanishi, Ryuichi Sakai, Koji Muramoto, Hisao Kamiya  Fisheries Science  68-  1635  -1636  2002/01   [Not refereed] [Not invited]  
    cDNA encoding the sea hare-derived antitumour-antibacterial protein Aplysianin A (APA) was expressed on Escherichia coli. APA displays sequence similarity to L-amino acid oxidase (LAAO) found in the snake {Crotalus atrox) venom. Spectrophotometric analysis along with thin layer chromatography of APA indicated that one flavin adenine dinucleotide, a cofactor of LAAO, bound to each subunit of the homotetramer. APA also displayed LAAO activity. Specifically, treatment of L-phenylalanine with APA resulted in the generation of hydrogen peroxide. This finding indicated that the antibacterial activity of APA is mainly caused by hydrogen peroxide production. © 2002, The Japanese Society of Fisheries Science. All rights reserved.
  • Hiroshi Yako, Mitsuru Jimbo, Ryuichi Sakai, Nobuhiko Takamatsu, Tadayoshi Shiba, Koji Muramoto, Hisao Kamiya  Fisheries Science  68-  1127  -1130  2002/01   [Not refereed] [Not invited]  
    Megabalanus rosa contained the C-type lectins as the major constituents of hemolymph proteins. BRA-1 (330 kDa) and BRA-2 (140 kDa) were composed of identical subunits (173 amino acids), and BRA-3 (64 kDa) of four same subunits (138 amino acids). These lectins were present in various tissues other than the hemolymph. However, only BRA-2 was detected in the organic matrix of shell by western blotting. Both BRA-2 and BRA-3 showed high association constants to calcium ions and inhibitory activity to CaCO3crystallization. The immobilized BRA-2 was found to promote the CaCO3crystallization. M. rosa lectins also showed opsonic activity when checked with murine macrophage. The gene structures of BRA-2 and BRA-3 were different from each other. These results suggest the participation in defense as well as biomineralization and the allotted biological role of M. rosa humoral lectins. © 2002, The Japanese Society of Fisheries Science. All rights reserved.
  • 神保充, 江頭浩司, 高橋正興, 得能大輔, 飯島亮介, 山崎正利, 村本光二, 酒井隆一, 神谷久男  日本分子生物学会年会プログラム・講演要旨集  26th-  583  2003/11   [Not refereed] [Not invited]
  • 酒井隆一, 吉田和文, 小池香苗, 神保充, 小池一彦, 湊早樹子, 神谷久男  天然有機化合物討論会講演要旨集  45th-  629-634  -634  2003/09   [Not refereed] [Not invited]
  • 神保充, 畠中聡, 飯島亮介, 酒井隆一, 山崎正利, 神谷久男  日本水産学会大会講演要旨集  2003-  253  2003/04   [Not refereed] [Not invited]
  • Yoshiaki Miyamoto, Ling Chen, Masahiro Sato, Masahiro Sokabe, Masahiro Sokabe, Toshitaka Nabeshima, Tony Pawson, Ryuichi Sakai, Nozomu Mori, Nozomu Mori, Nozomu Mori  Journal of Neuroscience  25-  1826  -1835  2005/02   [Not refereed] [Not invited]  
    N-Shc (neural Shc) (also ShcC), an adapter protein possessing two phosphotyrosine binding motifs [PTB (phosphotyrosine binding) and SH2 (Src homology 2) domains], is predominantly expressed in mature neurons of the CNS and transmits neurotrophin signals from the TrkB receptor to the Ras/mitogen-activated protein kinase (MAPK) pathway, leading to cellular growth, differentiation, or survival. Here, we demonstrate a novel role of ShcC, the modulation of NMDA receptor function in the hippocampus, using ShcC gene-deficient mice. In behavioral analyses such as the Morris water maze, contextual fear conditioning, and novel object recognition tasks, ShcC mutant mice exhibited superior ability in hippocampus-dependent spatial and nonspatial learning and memory. Consistent with this finding, electrophysiological analyses revealed that hippocampal long-term potentiation in ShcC mutant mice was significantly enhanced, with no alteration of presynaptic function, and the effect of an NMDA receptor antagonist on its expression in the mutant mice was notably attenuated. The tyrosine phosphorylation of NMDA receptor subunits NR2A and NR2B was also increased, suggesting that ShcC mutant mice have enhanced NMDA receptor function in the hippocampus. These results indicate that ShcC not only mediates TrkB-Ras/MAPK signaling but also is involved in the regulation of NMDA receptor function in the hippocampus via interaction with phosphotyrosine residues on the receptor subunits and serves as a modulator of hippocampal synaptic plasticity underlying learning and memory.
  • 吉田和史, 酒井隆一, 小池香苗, 小池一彦, 神保充, 神谷久男  日本水産学会大会講演要旨集  2003-  247  2003/04   [Not refereed] [Not invited]
  • 酒井隆一, 松原裕樹, 神保充, 神谷久男, 島本啓子, 浪越通夫  日本水産学会大会講演要旨集  2003-  247  2003/04   [Not refereed] [Not invited]
  • Kotaro Azuma, Kotaro Azuma, Kuniko Horie, Satoshi Inoue, Satoshi Inoue, Yasuyoshi Ouchi, Ryuichi Sakai  FEBS Letters  577-  339  -344  2004/11   [Not refereed] [Not invited]  
    There is accumulating evidence that the estrogen receptor (ER) can transduce specific signals at the plasma membrane. We tried to clarify the biological function of ER as a signaling molecule by identifying proteins that interact with the membrane-localized ER. The activation function 1 and 2 (AF-1 and AF-2) domains of ERα with or without the membrane-targeting sequence were stably expressed in the breast cancer cell line, MCF-7. The level of tyrosine phosphorylation of AF-2 was significantly elevated by the membrane localization. By mass-spectrometry analysis, α- and β-tubulins and heat shock protein 70 were identified as the AF-1-associated proteins. Of these, tubulins are associated only with membrane-targeted AF-1. © 2004 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.
  • 湊早樹子, 酒井隆一, 小池香苗, 小池一彦, 神保充, 神谷久男  日本水産学会大会講演要旨集  2003-  247  2003/04   [Not refereed] [Not invited]
  • Ryuichi Sakai, Ryuichi Sakai  Biotherapy  18-  397  -404  2004/09   [Not refereed] [Not invited]  
    Src family kinases have been investigated intensively in relationship to cancer development and progression, although their precise functions in cancer remain unclear. Numerous studies on Src family kinases to date have revealed them to be key molecules regulating proliferation, metastasis and invasion of tumor cells and most promising targets for anticancer therapeutics.
  • 酒井隆一, 鈴木克治, 石田真喜子, 神谷久男, 佐々木誠, 橘和夫, 小池達樹, 島本啓子, 波越通夫  天然有機化合物討論会講演要旨集  44th-  295-300  -300  2002/09   [Not refereed] [Not invited]
  • 酒井隆一, 神谷久男, 鈴木克治  日本水産学会大会講演要旨集  2004-  191  2004/03   [Not refereed] [Not invited]
  • Mitsuru Jimbo, Fumie Nakanishi, Ryuichi Sakai, Koji Muramoto, Hisao Kamiya  Fisheries Science  69-  1240  -1246  2003/12   [Not refereed] [Not invited]  
    L-amino acid oxidase (LAAO) activity, as well as mechanisms of antimicrobial action of aplysianin A, a sea hare-derived 340 kDa homotetrameric protein, was determined. Spectrophotometric and High-performance liquid chromatography analyses of aplysianin A indicated that one flavin adenine dinucleotide, a cofactor of LAAO, bound to each subunit of the homotetramer. Aplysianin A can specifically catalyze oxidation of basic amino acids (L-arginine and L-lysine), and is the first protein from marine invertebrate animals with LAAO activity. Substrate specificity of aplysianin A is markedly different from that of commonly known LAAO, such as snake venom LAAO, which prefer hydrophobic amino acids. Km value of aplysianin A was the smallest of those for all known LAAO reported. In the presence of catalase, the antibacterial activity of aplysianin A was inhibited as expected, indicating that the antibacterial action of aplysianin A results from hydrogen peroxide production during the reaction with substrates. Interestingly, aplysianin A acted as an antibacterial agent even in the presence of excess catalase. Antibacterial assays in various media suggested that this phenomenon was simply attributed to the consumption of amino acids required for bacterial growth in the media by aplysianin A.
  • 湊早樹子, 酒井隆一, 小池香苗, 小池一彦, 神保充, 神谷久男  日本水産学会大会講演要旨集  2004-  195  2004/03   [Not refereed] [Not invited]
  • 鈴木克治, 酒井隆一, 神谷久男  日本水産学会大会講演要旨集  2002-  201  2002/03   [Not refereed] [Not invited]
  • SAKAI R  J Am Chem Soc  108-  (20)  6404  -6405  1986/01   [Not refereed] [Not invited]
  • 本郷直人, 佐藤繁, 小藤田安希子, 酒井隆一, 児玉正昭  日本水産学会大会講演要旨集  2002-  215  2002/03   [Not refereed] [Not invited]
  • Masamitsu Tanaka, Masamitsu Tanaka, Riuko Ohashi, Riuko Ohashi, Ritsuko Nakamura, Kazuya Shinmura, Takaharu Kamo, Ryuichi Sakai, Haruhiko Sugimura  EMBO Journal  23-  1075  -1088  2004/03   [Not refereed] [Not invited]  
    Bidirectional signals mediated by Eph receptor tyrosine kinases and their membrane-bound ligands, ephrins, play pivotal roles in the formation of neural networks by induction of both collapse and elongation of neurites. However, the downstream molecular modules to deliver these cues are largely unknown. We report here that the interaction of a Rac1-specific guanine nucleotide-exchanging factor, Tiam1, with ephrin-B1 and EphA2 mediates neurite outgrowth. In cells coexpressing Tiam1 and ephrin-B1, Rac1 is activated by the extracellular stimulation of clustered soluble EphB2 receptors. Similarly, soluble ephrin-A1 activates Rac1 in cells coexpressing Tiam1 and EphA2. Cortical neurons from the E14 mouse embryos and neuroblastoma cells significantly extend neurites when placed on surfaces coated with the extracellular domain of EphB2 or ephrin-A1, which were abolished by the forced expression of the dominant-negative mutant of ephrin-B1 or EphA2. Furthermore, the introduction of a dominant-negative form of Tiam1 also inhibits neurite outgrowth induced by the ephrin-B1 and EphA2 signals. These results indicate that Tiam1 is required for neurite outgrowth induced by both ephrin-B1-mediated reverse signaling and EphA2-mediated forward signaling.
  • 成毛央人, 神保充, 酒井隆一, 村本光二, 神谷久男  日本水産学会大会講演要旨集  2002-  213  2002/03   [Not refereed] [Not invited]
  • Jinhong Huang, Jinhong Huang, Tamae Asawa, Tsuyoshi Takato, Ryuichi Sakai  Journal of Biological Chemistry  278-  48367  -48376  2003/11   [Not refereed] [Not invited]  
    Src family kinases are major regulators of various integrin-mediated biological processes, although their functional roles and substrates in cancer metastasis are unknown. We explored the roles of Src family tyrosine kinases in cell migration and the spread of K-1735 murine melanoma cell lines with low or high metastatic potential. Corresponding to elevated cell motility and spreading ability, Fyn was selectively activated among Src family kinases, and the cell motility was blocked by an inhibitor of Src family kinases. Significant tyrosine phosphorylation of cortactin, stable complex formation between activated Fyn and cortactin, and co-localization of cortactin with Fyn at cell membranes were all observed only in cells with high metastatic potential. Both integrin-mediated Fyn activation and hyperphosphorylation of cortactin were observed 2-5 h after stimulation in highly metastatic cells, and they required de novo protein synthesis. We demonstrate that cortactin is a specific substrate and cooperative effector of Fyn in integrin-mediated signaling processes regulating metastatic potential.
  • 神保充, 佐藤愛, 酒井隆一, 神谷久男  日本水産学会大会講演要旨集  2001-  33  2001/04   [Not refereed] [Not invited]
  • KOIKE TATSUKI, SASAKI MAKOTO, TACHIBANA KAZUO, SAKAI RYUICHI, OIWA CHIE, KAMIYA HISAO  日本化学会講演予稿集  79th-  (2)  1023  2001/03   [Not refereed] [Not invited]
  • Sakai Ryuichi, Yoshida Kazufumi, Koike Kanae, Jimbo Mitsuru, Koike K., Minato Sakiko, Kamiya Hisao  天然有機化合物討論会講演要旨集  0-  (45)  629  -634  2003/09   [Not refereed] [Not invited]  
    Cellular localization of the marine sponge-derived excitatory amino acid dysiherbaine (1) was investigated using immunohistochemical methods. Dysiherbaine (1), isolated from a sponge Dysidea herbacea, selectively activates mammalian non-NMDA type glutamate receptors (GluRs) and induces seizure in mice. Recently 1 was found to have unusually high affinity towards GluR5 and 6, subtypes of kainite-type GluRs, and can activate these subtype receptors selectively in the heteromerically expressed receptor complex. These unusual actions of 1 to the neuronal receptors warrants its usefulness as a r...
  • 神保充, 佐藤愛, 矢野原泰士, 小池一彦, 酒井隆一, 村本光二, 神谷久男  日本分子生物学会年会プログラム・講演要旨集  23rd-  327  2000/11   [Not refereed] [Not invited]
  • 中西文恵, 大山智樹, 神保充, 酒井隆一, 神谷久男  日本水産学会大会講演要旨集  2000-  104  2000/09   [Not refereed] [Not invited]
  • 臼井梨香, 角井陽子, 西尾寛明, 神保充, 酒井隆一, 村本光二, 神谷久男  日本水産学会大会講演要旨集  2000-  104  2000/09   [Not refereed] [Not invited]
  • Geoffrey T. Swanson, Tim Green, Ryuichi Sakai, Anis Contractor, Wesley Che, Hisao Kamiya, Stephen F. Heinemann  Neuron  34-  589  -598  2002/05   [Not refereed] [Not invited]  
    Neuronal kainate receptors are assembled from subunits with dissimilar specificities for agonists and antagonists. The composite biophysical behavior of heteromeric kainate receptors is determined by intersubunit interactions whose nature is unclear. Here we use dysiherbaine, a selective kainate receptor agonist, to show that GluR5 subunits assembled in heteromeric GluR5/KA-2 kainate receptor complexes can gate current without concomitant activation of their partner KA-2 subunits. A long-lasting interaction between dysiherbaine and GluR5 subunits elicits a tonic current from GluR5/KA-2 receptors; subsequent cooperative gating of KA-2 subunits can be elicited by both agonists, such as glutamate, and some classically defined antagonists, such as CNQX. This study demonstrates that each type of subunit within a heteromeric kainate receptor contributes a distinct conductance upon activation by agonist binding, and therefore provides insight into the biophysical function of ionotropic glutamate receptors.
  • 矢野原泰士, 神谷久男, 神保充, 酒井隆一, 村本光二  日本水産学会大会講演要旨集  2000-  167  2000/04   [Not refereed] [Not invited]
  • Jinhong Huang, Hiroko Hamasaki, Tetsuya Nakamoto, Hiroaki Honda, Hisamaru Hirai, Masaki Saito, Tsuyoshi Takato, Ryuichi Sakai  Journal of Biological Chemistry  277-  27265  -27272  2002/07   [Not refereed] [Not invited]  
    The Crk-associated substrate (Cas) is a unique docking protein that possesses a repetitive stretch of tyrosine-containing motifs and an Src homology 3 (SH3) domain. Embryonic fibroblasts lacking Cas demonstrated resistance to Src-induced transformation along with impaired actin bundling and cell motility, indicating critical roles of Cas in actin cytoskeleton organization, cell migration, and oncogenesis. To gain further insight into roles of each domain of Cas in these processes, a compensation assay was performed by expressing a series of Cas mutants in Cas-deficient fibroblasts. The results showed that motifs containing YDxP were indispensable for actin cytoskeleton organization and cell migration, suggesting that CrkII-mediated signaling regulates these biological processes. The C-terminal Src-binding domain played essential roles in cell migration and membrane localization of Cas, although it was dispensable in the organization of actin stress fibers. Furthermore, the Src-binding domain was also a prerequisite for Src transformation possibly, because of its crucial role in the phosphorylation of Cas during transformation. Overall, differential uses of the Cas domains in individual biological processes were demonstrated.
  • 酒井隆一, 神谷久男, 日景  日本水産学会大会講演要旨集  2000-  165  2000/04   [Not refereed] [Not invited]
  • KODAMA MASAAKI, KOTAKI RYUICHI, SAKAI RYUICHI, SATO SHIGERU  食肉に関する助成研究調査成果報告書  17-  326-331  -331  1999/12   [Not refereed] [Not invited]
  • Tetsuya Nakamoto, Takahiro Suzuki, Jinhong Huang, Tomoko Matsumura, Sachiko Seo, Hiroaki Honda, Ryuichi Sakai, Hisamaru Hirai  Biochemical and Biophysical Research Communications  294-  635  -641  2002/01   [Not refereed] [Not invited]  
    p130Cas (Cas) is a docking protein that becomes tyrosine phosphorylated in v-Src- or v-Crk-transformed cells and in integrin-stimulated cells. Cas -/- fibroblasts show defects in stress fiber formation, cell spreading, cell migration, and transformation by activated Src. To further characterize the role of Cas in signaling, we compared the expression profile in Cas -/- fibroblasts with that in Cas-re-expressing fibroblasts using the microarray methods. In Cas -/- fibroblasts, the expression of heme oxygenase 1 and caveolin-1 was reduced, but the expression of procollagen 1 α 1, procollagen 3 α 1, procollagen 11 α 1, elastin, periostin, TSC-36, and MARCKS was enhanced. The domains in Cas necessary for the change varied among these genes. Activated Src reduced the expression of most of these genes both in Cas -/- and in Cas +/+ fibroblasts. These results suggest the existence of signaling pathways that emanate from Cas to gene expression. © 2002 Elsevier Science (USA). All rights reserved.
  • SATO SHIGERU, SAKAI RYUICHI, KODAMA MASAAKI  天然有機化合物討論会講演要旨集  41st-  403-408  -408  1999/09   [Not refereed] [Not invited]
  • Izumi Miyake, Izumi Miyake, Yuko Hakomori, Azusa Shinohara, Toshie Gamou, Masaki Saito, Akihiro Iwamatsu, Ryuichi Sakai  Oncogene  21-  5823  -5834  2002/01   [Not refereed] [Not invited]  
    Shc family of docking proteins, ShcA, ShcB and ShcC, play roles in cellular signal transduction by binding to phosphotyrosine residues of various activated receptor tyrosine kinases. Both ShcB and ShcC proteins are selectively expressed in the neural system of adult mouse tissues. In most of neuroblastoma cells, obvious tyrosine phosphorylation of ShcC was observed, whereas expression of ShcB was considerably low. Phosphoproteins associated with hyperphosphorylated ShcC were purified from neuroblastoma cell lines, and identified by mass-spectrometry. Anaplastic lymphoma kinase (ALK), which turned out to be one of these phosphoproteins, was constitutively activated and associated with the PTB domain of ShcC in three neuroblastoma cells. In vitro kinase assay revealed that ShcC is a potent substrate of the activated ALK kinase. The ALK gene locus was significantly amplified in both of these cell lines, suggesting that gene amplification leads to constitutive activation of the ALK kinase, which results in hyperphosphorylation of ShcC. Constitutive activation of ALK appeared to interfere with signals from other receptor tyrosine kinases. ALK-ShcC signal activation, possibly caused by co-amplification with the N-myc gene, might give additional effects on malignant tumor progression of neuroblastoma.
  • Tracy M. Saxton, Tracy M. Saxton, Tracy M. Saxton, Alec M. Cheng, Siew Hwa Ong, Yong Lu, Ryuichi Sakai, James C. Cross, James C. Cross, Tony Pawson, Tony Pawson  Current Biology  11-  662  -670  2001/05   [Not refereed] [Not invited]  
    Background: The mammalian Grb2 adaptor protein binds pTyr-X-Asn motifs through its SH2 domain, and engages downstream targets such as Sos1 and Gab1 through its SH3 domains. Grb2 thereby couples receptor tyrosine kinases to the Ras-MAP kinase pathway, and potentially to phosphatidylinositol (PI) 3′-kinase. By creating a null (Δ) allele of mouse Grb2, we have shown that Grb2 is required for endoderm differentiation at embryonic day 4.0. Results: Grb2 likely has multiple embryonic and post natal functions. To address this issue, a hypomorphic mutation, first characterized in the Caenorhabditis elegans Grb2 ortholog Sem-5, was engineered into the mouse Grb2 gene. This mutation (E89K) reduces phosphotyrosine binding by the SH2 domain. Embryos that are compound heterozygous for the null and hypomorphic alleles exhibit defects in placental morphogenesis and in the survival of a subset of migrating neural crest cells required for branchial arch formation. Furthermore, animals homozygous for the hypomorphic mutation die perinatally because of clefting of the palate, a branchial arch-derived structure. Analysis of E89K/Δ Grb2 mutant fibroblasts revealed a marked defect in ERK/MAP kinase activation and Gab1 tyrosine phosphorylation following growth factor stimulation. Conclusions: We have created an allelic series within mouse Grb2, which has revealed distinct functions for phosphotyrosine-Grb2 signaling in tissue morphogenesis and cell viability necessary for mammalian development. The placental defects in E89K/Δ mutant embryos are reminiscent of those seen in receptor tyrosine kinase-, Sos1-, and Gab1deficient embryos, consistent with the finding that endogenous Grb2 is required for efficient RTK signaling to the Ras-MAP kinase and Gab1 pathways.
  • Sakai Ryuichi, Suzuki Katsuji, Ishida Makiko, Kamiya Hisao, Sasaki Makoto, Tachibana Kazuo, Koike Tatsuki, Shimamoto Keiko, Namikoshi Michio  天然有機化合物討論会講演要旨集  0-  (44)  295  -300  2002/09   [Not refereed] [Not invited]  
    Excitatory amino acids bind and activate ionotropic glutamate receptors (iGluR) in central nervous system (CNS). Since iGluR is a highly diverse class of the synaptic receptors both structurally and functionally, highly selective agonists and antagonists are in demand as tools to understand their roles in the CNS. Here, we report isolation, structure, and biological activities of excitatory amino acids and related compounds from sponges collected in the Micronesian waters. Dysidea herbacea collected in Yap state afforded isolations of neodysiherbaine A (2), a related compound of dysiherbain...
  • 矢野原泰士, 神保充, 小池一彦, 酒井隆一, 神谷久男, 村本光二  日本水産学会大会講演要旨集  1999-  189  1999/04   [Not refereed] [Not invited]
  • Makoto Sasaki, Tatsuki Koike, Ryuichi Sakai, Kazuo Tachibana  Tetrahedron letters  41-  (20)  3923  -3926  2000/05   [Not refereed] [Not invited]  
    A total synthesis of (-)-dysiherbaine, a neuroexcitotoxic amino acid isolated from the Micronesian marine sponge Dysidea herbacea, starting from a carbohydrate precursor, is described. The present synthesis features a palladium(0)-catalyzed cross-coupling of the 6/5-bicyclic core with an amino acid residue. (C) 2000 Elsevier Science Ltd.
  • 佐藤繁, 酒井隆一, 坂本節子, 児玉正昭  日本水産学会大会講演要旨集  1999-  185  1999/04   [Not refereed] [Not invited]
  • Ryuichi Sakai, Ryuichi Sakai, Jeffrey T. Henderson, John P. O'Bryan, Andrew J. Elia, Tracy M. Saxton, Tracy M. Saxton, Tony Pawson, Tony Pawson  Neuron  28-  819  -833  2000/12   [Not refereed] [Not invited]  
    Shc proteins possess SH2 and PTB domains and serve a scaffolding function in signaling by a variety of receptor tyrosine kinases. There are three known mammalian Shc genes, of which ShcB and ShcC are primarily expressed in the nervous system. We have generated null mutations in ShcB and ShcC and have obtained mice lacking either ShcB or ShcC or both gene products. ShcB-deficient animals exhibit a loss of peptidergic and nonpeptidergic nociceptive sensory neurons, which is not enhanced by additional loss of ShcC. Mice lacking both ShcB and ShcC exhibit a significant loss of neurons within the superior cervical ganglia, which is not observed in either mutant alone. The results indicate that these Shc family members possess both unique and overlapping functions in regulating neural development and suggest physiological roles for ShcB/ShcC in TrkA signaling.
  • 神谷久男, 矢野原泰士, 神保充, 小池一彦, 小池香苗, 酒井隆一, 村本光二  日本水産学会大会講演要旨集  1999-  188  1999/04   [Not refereed] [Not invited]
  • Ryuichi Sakai, Chie Oiwa, Kojiroh Takaishi, Hisao Kamiya, Michito Tagawa  Tetrahedron Letters  40-  (38)  6941  -6944  1999/09   [Not refereed] [Not invited]  
    A new α,α-disubstituted α-amino acid derivative, dysibetaine (1), was isolated from an aqueous extract of the marine sponge Dysidea herbacea collected in Yap, Micronesia. The structure of 1, (2R*,4R*)-2-(trimethylammonium)methyl-4-hydroxy-5-oxoprolinate, was determined by spectral methods and X-ray crystallography.
  • 神谷久男, 神保充, 酒井隆一, 井田斎, 村本光二  日本水産学会大会講演要旨集  1998-  135  1998/09   [Not refereed] [Not invited]
  • Tetsuya Nakamoto, Tetsuya Yamagata, Ryuichi Sakai, Seishi Ogawa, Seishi Ogawa, Hiroaki Honda, Hiroo Ueno, Naoto Hirano, Yoshio Yazaki, Hisamaru Hirai, Hisamaru Hirai  Molecular and Cellular Biology  20-  1649  -1658  2000/03   [Not refereed] [Not invited]  
    p130(cas) (Cas) is a docking protein that contains an SH3 domain and multiple tyrosine residues, p130(cas) is located at focal adhesions, is tyrosine phosphorylated in response to integrin stimulation, and is thought to transmit signals, via c-Crk and other proteins, for the remodeling of actin stress fibers and cell movement. In a search for the ligands of the SH3 domain of p130(cas) by far-Western screening, we cloned a novel protein named CIZ (for Cas-interacting zinc finger protein). CIZ consists of the following: a putative leucine zipper; a serine/threonine-rich region; a proline-rich sequence; five, six, or eight Kruppel-type C 2 H 2 zinc fingers; and the glutamine-alanine repeat. CIZ binds Cas in cells and is located in the nucleus and at focal adhesions. We showed that CIZ is a nucleocytoplasmic shuttling protein, by using the transient interspecies heterokaryon formation assay. In order to search for the targets of CIZ in nucleus, we determined the DNA binding consensus of CIZ as (G/C)AAAAA(A) by cyclic amplification and selection of targets analysis. The consensus-like sequences are found in several promoters of matrix metalloproteinases (MMPs), which are the enzymes used to degrade the extracellular matrix proteins. CIZ binds to a consensus- like sequence in the MMP-1 (collagenase) promoter. Overexpression of CIZ upregulates the transcriptions from MMP-1, MMP-3 (stromelysin), and MMP-7 (matrilysin) promoters, and this transactivation was enhanced in the presence of Cas. Furthermore, the stable overexpression of CIZ promoted the production of MMP-7 in culture medium. In summary, CIZ, a novel zinc finger protein, binds Cas, is a nucleocytoplasmic shuttling protein, and regulates the expression of MMPs.
  • 松原裕樹, 神谷久男, 酒井隆一  日本水産学会大会講演要旨集  1998-  136  1998/09   [Not refereed] [Not invited]
  • Makoto Sasaki, Takahiro Maruyama, Ryuichi Sakai, Kazuo Tachibana  Tetrahedron Letters  40-  (16)  3195  -3198  1999/04   [Not refereed] [Not invited]  
    Synthesis of dysiherbaine model compound 2 and its diastereomer 3 is described. The structurally simplified model compound 2, lacking the hydroxyl and N-methyl groups on the tetrahydropyran ring, induced convulsive behavior in mice upon intracerebral injections.
  • 大岩智恵, 神谷久男, 酒井隆一  日本水産学会大会講演要旨集  1998-  136  1998/09   [Not refereed] [Not invited]
  • SAKAI RYUICHI, KAMIYA HISAO, SHIMAMOTO KEIKO, HORIKAWA YOSHIKO, MIYAMAE TAKEAKI  日本水産学会大会講演要旨集  1998-  177  1998/04   [Not refereed] [Not invited]
  • Hiroaki Honda, Tetsuya Nakamoto, Ryuichi Sakai, Hisamaru Hirai  Biochemical and Biophysical Research Communications  262-  25  -30  1999/08   [Not refereed] [Not invited]  
    p130(Cas) (Cas) is an adaptor molecule which becomes tyrosine phosphorylated by v-Src- or v-Crk-triggered transformation and several physiological stimuli, such as cell attachment to fibronectin. We previously generated mice lacking Cas and demonstrated that Cas functions as an assembling molecule of actin filaments. To further explore Cas role in cellular function, we established Cas-deficient and Cas-re-expressing fibroblasts and compared their behaviors in response to several biological stimuli. We found that Cas-deficient fibroblasts showed significant defects in cell movement after mechanical wounding and in cell migration toward fibronectin as compared with Cas-re-expressing cells. In addition, when plated on fibronectin-coated dishes, Cas-deficient cells exhibited a significant delay in cell spreading as compared with Cas-re-expressing cells albeit that protein-tyrosine phosphorylation was similarly induced. These results demonstrated that Cas functions as a molecule promoting cell movement, cell migration, and cell spreading and suggest that Cas would be implicated in various physiological and pathological processes, such as would healing, chemotaxis, and tumor invasion.
  • YAMAGUCHI MASATO, JINBO MITSURU, SAKAI RYUICHI, MURAMOTO KOJI, KAMIYA HISAO  日本水産学会大会講演要旨集  1997-  186  1997/04   [Not refereed] [Not invited]
  • KAMIYA HISAO, JINBO MITSURU, SAKAI RYUICHI, KOIKE KAZUHIKO, MURAMOTO KOJI  日本水産学会大会講演要旨集  1998-  149  1998/04   [Not refereed] [Not invited]
  • M. Yamaguchi, M. Jimbo, R. Sakai, K. Muramoto, H. Kamiya  Comparative Biochemistry and Physiology - B Biochemistry and Molecular Biology  122-  363  1999/01   [Not refereed] [Not invited]
  • YAMAGUCHI MASAHITO, SAKAI RYUICHI, JINBO MITSURU, KAMIYA HISAO  日本水産学会大会講演要旨集  1996-  110  1996/10   [Not refereed] [Not invited]
  • Sato Shigeru, Sakai Ryuichi, Kodama Masaaki  天然有機化合物討論会講演要旨集  0-  (41)  403  -408  1999/09   [Not refereed] [Not invited]  
    Gonyautoxins 1-4 (GTXs) are 11-O-sulfated analogues of saxitoxins (STXs). These compounds block voltage-gated sodium channels at very low concentration and cause paralytic shellfish poisonings. GTXs have been shown to be transformed reductively into STXs by homogenates of accumulating organisms or by bacteria. On the other hand, mild chemical treatment of GTXs with thiol reagents such as glutathione or 2-mercaptoethanol also results in the formation of STXs. Although the machanism of these transformations have risen intriguing questions, no detailed study has been conducted. Herein, we desc...
  • Michitoshi Toda, Mitsuru Jimbo, Koji Muramoto, Ryuichi Sakai, Hisao Kamiya  Fisheries Science  64-  638  -642  1998/08   [Not refereed] [Not invited]  
    The hemolymph of the acorn barnacle Balanus rostratus showed hemagglutinating activity and inhibition of calcium carbonate crystallization. A lectin having D-galactose-binding specificity was isolated from the hemolymph by a combination of affinity chromatography on acid-treated agarose gel and HPLC. The purified lectin was dependent on the presence of calcium ion for hemagglutinating activity. In SDS-PAGE, it gave one protein band (25 kDa) under a reduced condition, while it gave two components (35 and 95 kDa) without a reducing agent. The molecular mass of the intact lectin was estimated to be 120 kDa by HPLC on TSK G-3000SW. Isolectric point was determined to be pH 4.4. The same amino-terminal sequence, Tyr-Val-Ser-Asn-Gln-Ser-Val-Glu-Pro-Asp-Ser-Ala-Asp-Thr-Ala, was obtained with the purified lectin as well as the components observed in SDS-PAGE. The purified lectin did not inhibit calcium carbonate crystallization at 1 mg/30 ml, although the hemolymph inhibited the crystallization at 0.1 mg protein/30 ml. The inhibitory factor(s) was an acidic and small molecular-weight compound(s).
  • Alec M. Cheng, Alec M. Cheng, Tracy M. Saxton, Ryuichi Sakai, Sarang Kulkarni, Geraldine Mbamalu, Wolfgang Vogel, Christopher G. Tortorice, Robert D. Cardiff, James C. Cross, William J. Muller, Tony Pawson  Cell  95-  793  -803  1998/12   [Not refereed] [Not invited]  
    Proteins with SH2 and SH3 domains link tyrosine kinases to intracellular pathways. To investigate the biological functions of a mammalian SH2/SH3 adaptor, we have introduced a null mutation into the mouse gene for Grb2. Analysis of mutant embryonic stem cells, embryos, and chimeras reveals that Grb2 is required during embyrogenesis for the differentiation of endodermal cells and formation of the epiblast. Grb2 acts physiologically as an adaptor, since replacing the C terminus of the Ras activator Sos1 with the Grb2 SH2 domain yields a fusion protein that largely rescues the defects caused by the Grb2 mutation. Furthermore, Grb2 is rate limiting for mammary carcinomas induced by polyomavirus middle T antigen. These data provide genetic evidence for a mammalian Grb2-Ras signaling pathway, mediated by SH2/SH3 domain interactions, that has multiple functions in embryogenesis and cancer.
  • SAKAI RYUICHI, KAMIYA HISAO, HARAYAMA SHIGEAKI, ONISHI TOMOKO  研究基盤施設合同シンポジウム講演予稿集  1996-  79-84  -84  1996/09   [Not refereed] [Not invited]
  • SAKAI RYUICHI, KAMIYA HISAO, MURATA MICHIO  天然有機化合物討論会講演要旨集  38th-  463-468  -468  1996/09   [Not refereed] [Not invited]
  • KAMIYA HISAO, SAKAMOTO SETSUKO, YOSHIKATA YOKO, SAKAI RYUICHI, TOCHIMOTO TAKEYOSHI  日本水産学会大会講演要旨集  1996-  161  1996/03   [Not refereed] [Not invited]
  • Hiroaki Honda, Hideaki Oda, Tetsuya Nakamoto, Zen Ichiro Honda, Ryuichi Sakai, Takahiro Suzuki, Toshiki Saito, Kenji Nakamura, Kazuki Nakao, Takatoshi Ishikawa, Motoya Katsuki, Yoshio Yazaki, Hisamaru Hirai  Nature Genetics  19-  361  -365  1998/08   [Not refereed] [Not invited]  
    p130(Cas) (Cas), the protein encoded by the Crkas gene (also known as Cas), is an adaptor molecule with a unique structure that contains a Src homology (SH)-3 domain followed by multiple YXXP motifs and a proline-rich region. Cas was originally cloned as a highly tyrosine-phosphorylated protein in cells transformed by v-Src (refs 2,3) or v-Crk (ref. 4) and has subsequently been implicated in a variety of biological processes including cell adhesion, cell migration, growth factor stimulation, cytokine receptor engagement and bacterial infection. To determine its role in vivo, we generated mice lacking Cas. Cas-deficient embryos died in utero showing marked systemic congestion and growth a retardation. Histologically, the heart was poorly developed and blood vessels were prominently dilated. Electron microscopic analysis of the heart revealed disorganization of myofibrils and disruption of Z-disks. In addition, actin stress fiber formation was severely impaired in Cas-deficient primary fibroblasts. Moreover, expression of activated Src in Cas-deficient primary fibroblasts did not induce a fully transformed phenotype, possibly owing to insufficient accumulation of actin cytoskeleton in podosomes. These findings have defined Cas function in cardiovascular development, actin filament assembly and Src- induced transformation.
  • SAKAI RYUICHI, KAMISATO TAKANORI, YABUKI AYUMI, YONEZU AYAKO, TAKAYAMA MASAHIKO, KAMIYA HISAO  日本水産学会大会講演要旨集  1996-  163  1996/03   [Not refereed] [Not invited]
  • YAMAGUCHI MASATO, MURAMOTO KOJI, SAKAI RYUICHI, KAMIYA HISAO  日本水産学会大会講演要旨集  1996-  161  1996/03   [Not refereed] [Not invited]
  • T. Yamagata, J. Nishida, R. Sakai, T. Tanaka, Y. Yazaki, H. Hirai  Leukemia  11-  501  -502  1997/08   [Not refereed] [Not invited]  
    Interleukin-5 (IL-5) is produced by T lymphocytes and known to support B cell growth and eosinophilic differentiation of the progenitor cells. Using ATL-16T cells which express IL-5 mRNA, we have identified a region, within the human IL-5 gene promoter, that regulates IL-5 gene transcription. This cis-acting sequence contains the core binding motif, (A/T)GATA(A/G), for GATA-binding family proteins and thus suggests the involvement of these family members. In this report, we describe the cloning of human GATA-4 (hGATA-4) and show that hGATA-4 selectively interacts with the -70 GATA site within the IL-5 proximal promoter region. By promoter deletion and mutation analyses, we established this region as a positive regulatory element. Cotransfection experiments revealed that both hGATA-4 and PMA/A23187 stimulation are necessary for the IL-5 promoter activation. The requirement of another regulatory element called CLEO, which lies downstream of the -70 GATA site, was also demonstrated. ATL-16T cells express mRNA of three GATA-binding proteins, hGATA-2, hGATA-3 and hGATA-4 and each of them has a potential to bind to the consensus (A/T)GATA(G/A) motif. However, using ATL-16T nuclear extract, we demonstrated that GATA-4 is the only GATA-binding protein that forms specific DNA-protein complex with the -70 GATA site. The electrophoretic mobility shift assay with extracts of COS cells expressing GATA-binding proteins showed that GATA-4 has the highest binding affinity to the -70 GATA site among the three GATA-binding proteins. When the transactivation ability was compared among the three, GATA-4 showed the highest activity. These results demonstrate the selective role of GATA-4 in the transcriptional regulation of the IL-5 gene in a circumstance where multiple members of the GATA-binding proteins are expressed.
  • 山口政人, 伊藤晃一, 坂本節子, 酒井隆一, 神谷久男, 渡辺真理代  日本水産学会大会講演要旨集  1995-  316  1995/04   [Not refereed] [Not invited]
  • Tetsuya Nakamoto, Ryuichi Sakai, Ryuichi Sakai, Hiroaki Honda, Seishi Ogawa, Hiroo Ueno, Takahiro Suzuki, Shin Ichi Aizawa, Yoshio Yazaki, Hisamaru Hirai, Hisamaru Hirai  Molecular and Cellular Biology  17-  3884  -3897  1997/07   [Not refereed] [Not invited]  
    p130(cas) (Cas) is an adapter protein that has an SH3 domain followed by multiple SH2 binding motifs in the substrate domain. It also contains a tyrosine residue and a proline-rich sequence near the C terminus, which are the binding sites for the SH2 and SH3 domains of Src kinase, respectively. Cas was originally identified as a major tyrosine-phosphorylated protein in v-Crk- and v-Src-transformed cells. Subsequently, Cas was shown to be inducibly tyrosine phosphorylated upon integrin stimulation; it is therefore regarded as one of the focal adhesion proteins. Using an immunofluorescence study, we examined the subcellular localization of Cas and determined the regions required for its localization to focal adhesions. In nontransformed cells, Cas was localized predominantly to the cytoplasm and partially to focal adhesions. However, in 527F-c-Src-transformed cells , Cas was localized mainly to podosomes, where the focal adhesion proteins are assembled. The localization of Cas to focal adhesions was also observed in cells expressing the kinase-negative 527F/295M-c-Src. A series of analyses with deletion mutants expressed in various cells revealed that the SH3 domain of Cas is necessary for its localization to focal adhesions in nontransformed cells while both the SH3 domain and the C-terminal Src binding domain of Cas are required in 527F-c-Src-transformed cells and fibronectin-stimulated cells. In addition, the localization of Cas to focal adhesions was abolished in Src- negative cells. These results demonstrate that the SH3 domain of Cas and the association of Cas with Src kinase play a pivotal role in the localization of Cas to focal adhesions.
  • 坂本節子, 伊藤晃一, 山口政人, 酒井隆一, 神谷久男, 渡辺真利代, 渡辺真之  日本水産学会大会講演要旨集  1995-  315  1995/04   [Not refereed] [Not invited]
  • 戸田道寿, 今井利樹, 八子博, 坂本節子, 酒井隆一, 村本光二, 神谷久男  日本水産学会大会講演要旨集  1995-  79  1995/04   [Not refereed] [Not invited]
  • Ryuichi Sakai, Ryuichi Sakai, Tetsuya Nakamoto, Keiya Ozawa, Shin Ichi Aizawa, Hisamaru Hirai  Oncogene  14-  1419  -1426  1997/01   [Not refereed] [Not invited]  
    The cellular transformation by v-Src or v-Crk induces tyrosine phosphorylation of a common substrate molecule, p130(Cas), which tightly binds these oncoproteins in vivo. From its structure, Cas is deduced to be an ideal substrate for Src family kinases and Abl kinase. The tyrosine kinase activity associated with Cas was analysed using mouse variant fibroblasts lacking at least one of tyrosine kinases. In normal fibroblasts, Cas is associated with a significant level of tyrosine kinase activity which efficiently phosphorylates Cas in vitro. The Cas-associated tyrosine kinase activity was remarkably elevated in Csk(-/-) cells, which resulted in hyperphosphorylation of cellular Cas. The associated kinase activity was slightly increased in Src(-/-) cells whereas not significantly changed in Abl(-/-) nor Fak(-/-) cells. On the contrary, the Cas-associated kinase activity was remarkably decreased in Fyn(-/-) cells. At the same time, association of Cas with Fyn kinase in vitro was most obviously detected in normal fibroblasts as well as Csk(-/-) cells. Transient expression of v-Crk induced elevation of the Cas-associated kinase activity in all of these cell lines except the primary culture of Fyn(-/-) fibroblasts. These results indicate that Fyn kinase plays an essential role in v-Crk-mediated phosphorylation of Cas.
  • Akira Gomi, Souji Shinoda, Ryuichi Sakai, Hisamaru Hirai, Keiya Ozawa, Toshio Masuzawa  Biochemical and Biophysical Research Communications  227-  558  -563  1996/10   [Not refereed] [Not invited]  
    We investigated the expression of DNA polymerase β (β-pol) and O 6 -methylguanine-DNA methyltransferase (MGMT) in human glioma cells with acquired resistance to 1-(4-amino-2-methyl-5-pyrimidinyl)-methyl-3-(2-chloroethyl)-3- nitrosourea (ACNU) and in the parent cells. ACNU-resistant T430 (T430R) and A172 (A172R) glioma cell lines were established following repeated exposure to ACNU. The level of MGMT mRNA expression was elevated in T430R, but not in A172R. In contrast, the level of β-pol mRNA expression and the level of β-pol protein were elevated in A172R, compared with the parent cells. While the mechanism of MGMT repair has been considered to be important in the drug resistance of human brain tumors to ACNU, our present results demonstrate that β-pol may also play an important role in the acquisition of tumor cell resistance to ACNU in human gliomas.
  • Ryuichi Sakai, Elizabeth A. Jares-Erijman, Ignacio Manzanares, Maria V. Silva Elipe, Kenneth L. Rinehart  Journal of the American Chemical Society  118-  9017  -9023  1996/09   [Not refereed] [Not invited]  
    New bioactive ecteinascidins (Et's) 597 (1), 583 (2), 594 (3), and 596 (4)-putative biosynthetic precursors of previously described Et's [e.g., Et 743 (5)]-were isolated from the Caribbean tunicate Ecteinascidia turbinata. Structures assigned to these compounds based on spectroscopic data represent a novel series of Et's with L-cysteine or its α-oxo analog as unit C. The absolute configuration of the L-Cys unit of 1 was assigned by chiral GC, while a 2D ROESY (rotating-frame Overhauser enhancement spectroscopy) spectrum of its acetyl derivative 1a completed the assignment of the stereochemistry of 1 as 1R,2R,3R,4R,11R,13S,21S, 1'R.
  • Y. Nojima, T. Mimura, N. Morino, K. Hamasaki, H. Furuya, R. Sakai, T. Nakamoto, Y. Yazaki, H. Hirai  Human cell : official journal of Human Cell Research Society  9-  169  -174  1996/09   [Not refereed] [Not invited]  
    Integrins comprise the major class of receptors used by cells to interact with the extracellular matrix. Integrin/matrix interactions play a critical role in a variety of biological processes, including embryonic development, wound healing, tumor metastasis, cell growth and differentiation. It is now evident that integrins can transduce biochemical signals across the plasma membrane to the cell interior. Protein tyrosine phosphorylation has attracted much attention as an important regulator for integrin-mediated signal transduction. Recently, we have identified a novel signaling molecule, p130Cas, which participates in integrin-mediated signal transduction. p130Cas was originally identified as a protein hyperphosphorylated in cells expressing transforming gene products p47v-crk (v-Crk) and p60v-crk (v-Src). In this brief review, we will discuss about a role of p130Cas in signal transduction triggered by cell adhesion and transformation.
  • Tetsuya Yamagata, Junji Nishida, Tomoyuki Tanaka, Ryuichi Sakai, Kinuko Mitani, Mitsuaki Yoshida, Tadatsugu Taniguchi, Yoshio Yazaki, Hisamaru Hirai, Hisamaru Hirai  Molecular and Cellular Biology  16-  1283  -1294  1996/04   [Not refereed] [Not invited]  
    We have isolated a novel cDNA clone encoding interferon (IFN) consensus sequence-binding protein in adult T-cell leukemia cell lines or activated T cells (ICSAT); this protein is the human homolog of the recently cloned Pip/LSIRF. ICSAT is structurally most closely related to the previously cloned ICSBP, a member of the IFN regulatory factor (IRF) family of proteins that binds to interferon consensus sequences (ICSs) found in many promoters of the IFN-regulated genes. Among T-cell lines investigated, ICSAT was abundantly expressed in human T-cell leukemia virus type 1 (HTLV-1)-infected T cells. When the HTLV-1 tax gene was expressed or phorbol myristate acetate-A23187 stimulation was used, ICSAT expression was induced in Jurkat cells which otherwise do not express ICSAT. When the binding of ICSAT to four different ICSs was tested, the relative differences in binding affinities for those ICSs were determined. To study the functional role of ICSAT, we performed cotransfection experiments with the human embryonal carcinoma cell line N-Tera2. ICSAT was demonstrated to possess repressive function over the gene activation induced by IFN stimulation or by IRF-1 cotransfection. Such repressive function is similar to that seen in IRF-2 or ICSBP. However, we have found that ICSAT has a different repressive effect from that of IRF-2 or ICSBP in some IFN-responsive reporter constructs. These results suggest that a novel mechanism of gene regulation by "differential repression" is used by the multiple members of repressor proteins with different repressive effects on the IFN-responsive genes.
  • Yoshihisa Nojima, Yoshihisa Nojima, Noritsugu Morino, Toshihide Mimura, Ken Hamasaki, Hiroko Furuya, Ryuichi Sakai, Toshiya Sato, Kouichi Tachibana, Chikao Morimoto, Yoshio Yazaki, Hisamaru Hirai  Journal of Biological Chemistry  270-  15398  -15402  1995/06   [Not refereed] [Not invited]  
    p130 Cas (Cas) has been recently identified as a 130-kDa protein that is highly phosphorylated on tyrosine residues and is stably associated with p4T v-crk (v-Crk) and p60 v-src (v.Src) oncogene products in cells transformed by the respective genes. Cas is a novel signaling molecule having a single Src homology (SH) 3 domain and a cluster of multiple SH2-binding motifs. While the tight association of Cas with v-Crk and v-Src is strongly suggestive of a significant role in regulating cellular transformation, the function of Cas in normal untransformed cells is totally unknown. We report here that cell adhesion to fibronectin rapidly promotes tyrosine phosphorylation of Cas in human and rat fibroblast cell lines. The response was equally induced by cell adhesion to plates coated with vitronectin, laminin, and collagen but not by cell attachment to nonspecific substrate poly-L-lysine. The kinetic profile of Cas phosphorylation was almost identical with that of tyrosine phosphorylation of focal adhesion kinase pp125 FAK (Fak), which is well known to be activated subsequent to integrin-mediated cell adhesion. Adhesion-dependent Cas phosphorylation was completely inhibited by treating cells with cytochalasin D, an agent that disrupts polymerization of actin stress fibers. These results suggest that tyrosine phosphorylation of Cas is stimulated by normal cell adhesion in close association with Fak phosphorylation and the formation of actin stress fibers. In v-Src- or v-Crk-transformed cells, however, the tyrosine phosphorylation of Cas is markedly increased in an adhesion-independent manner that is insensitive to treatment with cytochalasin D. Thus, Cas plays a role in signaling pathways mediated by cell adhesion as well as by transformation. We propose that Cas may amplify and propagate integrin-mediated signals by interacting with SH2-containing molecule(s).
  • Sakai Ryuichi, Kamiya Hisao, Murata Michio  天然有機化合物討論会講演要旨集  0-  (38)  463  -468  1996/09   [Not refereed] [Not invited]  
    A new amino acid dysiherbaine (1), was isolated from a Micronesian sponge Dysidea herbacea. The structure was determined spectroscopically by using FABMS, ESIMS, FABMS/CID/MS, and one- and two-dimensional NMR experiments of 1 and its dimethyl derivative 2 to be a novel di-amino di-carboxylic acid, which consisted of a cis fused-hexahydrofuro[3,2-b] pyran ring substituted with a 3-[2-amino propanoic acid] side chain. The relative configuration of the bicyclic portion of 1 was determined by 3^J_analysis and deference NOE experiments, and that of acyclic side chain was assigned by additio...
  • Bruce J. Mayer, Hisamaru Hirai, Ryuichi Sakai  Current Biology  5-  296  -305  1995/01   [Not refereed] [Not invited]  
    Background: Non-receptor protein-tyrosine kinases often contain at least one Src homology 2 (SH2) domain, a protein module that binds with high affinity to tyrosine-phosphorylated peptides. Because SH2 domains would be predicted to bind with high affinity to proteins phosphorylated by the kinase, but not to the unphosphorylated substrate, their presence in tyrosine kinases has been puzzling. An important role for the SH2 domain of the Abl tyrosine kinase was suggested by work showing that Abl requires an intact SH2 domain in order to malignantly transform cells, and that replacement of the Abl SH2 domain with heterologous SH2 domains alters the spectrum of proteins phosphorylated detectably by Abl in vivo. Results We have used purified wild-type and mutant Abl kinases to examine the roles of the Abl's SH2 and catalytic domains in phosphorylation of p130 CAS , a model substrate that has multiple potential phosphorylation sites. We find that an SH2 domain is required for efficient hyperphosphorylation of p130 in vitro. We use chimeric mutants with heterologous SH2 domains to demonstrate that the SH2 domain of the oncogenically transforming adaptor protein Crk, which is the SH2 domain predicted to bind with highest affinity (of those tested) to potential phosphorylation sites in p130, is best able to facilitate hyperphosphorylation. This is the case whether the catalytic domain of the kinase is derived from Abl or from its distant relative, Src. These studies also reveal a role for binding of Crk to Abl in mediating phosphorylation by the kinase. Using purified proteins, we demonstrate that association with Crk strikingly enhances the ability of Abl to hyperphosphorylate p130. There is an excellent correlation between the ability of mutant Crk proteins to promote hyperphosphorylation of p130 by Abl and their ability to transform rodent fibroblasts. Conclusion Our data suggest that, ultimately, the substrate specificity of a non-receptor tyrosine kinase is dependent on the binding specificity of its associated SH2 domain. The SH2 domain binds tightly to a subset of proteins phosphorylated by the catalytic domain, leading to processive phosphorylation of those proteins. Substrate specificity can be broadened by an association between the kinase and proteins, such as Crk, that contain additional SH2 domains; this may play a role in malignant transformation by Crk. © 1995 Elsevier Science Ltd. All rights reserved.
  • Ryuichi Sakai, Justin G. Stroh, David W. Sullins, Kenneth L. Rinehart  Journal of the American Chemical Society  117-  3734  -3748  1995/01   [Not refereed] [Not invited]  
    Seven new didemnins—didemnins M (1), N (2), X (3), and Y (4), nordidemnin N (5), epididemnin A 1 (6), and acyclodidemnin A (7)—were isolated from an extract of the Caribbean tunicate Trididemnum solidum. The structures of these compounds were assigned, based on FABMS, high-field NMR data, and chemical degradation studies. Biological activities of these peptides are also described. © 1995, American Chemical Society. All rights reserved.
  • Naoto Hirano, Naoto Hirano, Futoshi Shibasaki, Ryuichi Sakai, Tomoyuki Tanaka, Junji Nishida, Yoshio Yazaki, Tadaomi Takenawa, Hisamaru Hirai, Hisamaru Hirai  European Journal of Biochemistry  234-  336  -342  1995/01   [Not refereed] [Not invited]  
    Recently it was shown that putative phospholipase C‐α cDNA does not code for an isotype of the phospholipase C superfamily but for one of the glucose‐regulated proteins (GRPs), ERp57/GRP58. We have isolated human ERp57/GRP58 cDNA from human placenta. Sequence analysis showed that ERp57/GRP58 has two Trp‐Cys‐Gly‐His‐Cys‐Lys motifs completely conserved among the mammals. Bacterially expressed recombinant ERp57/GRP58 protein contained a thiol‐dependent reductase activity which was completely abolished when Ser residues were substituted for Cys residues in both of the two motifs. Furthermore, we have identified a soluble form of ERp57/GRP58 by Western blotting and biosynthetic labeling. In v‐onc transformants of normal rat kidney cells, the expression level of ERp57/GRP58 was elevated at the protein level. In NIH3T3 cells transformed with v‐src, activated c‐src (Y527F) or c‐src, the expression level of ERp57/GRP58 was upregulated in proportion to their transforming abilities. These results indicate that a soluble form of ERp57/GRP58 exists and that this protein may control both extracellular and intracellular redox activities through its thiol‐dependent reductase activity. Moreover, it is likely that ERp57/GRP58 is involved in the oncogenic transformation. Copyright © 1995, Wiley Blackwell. All rights reserved
  • Akira Gomi, Ryuichi Sakai, Seishi Ogawa, Souji Shinoda, Hisamaru Hirai, Toshio Masuzawa  Japanese Journal of Cancer Research  86-  342  -346  1995/01   [Not refereed] [Not invited]  
    Studies have shown that homozygous deletion of the cyclin‐dependent kinase‐4 inhibitor (CDK41) gene, which is mapped to chromosome 9p21, is frequently observed in various types of human cancers. Here we report that the CDK4I gene was deleted in gliomas. Eight cell lines derived from glioblastomas and samples from 14 patients with various grades of gliomas were examined by Southern blot analysis. We found that the CDK4I gene was deleted in 7 of 8 (87.5%) cell lines and 7 of 9 (78%) samples from high‐grade glioma patients, whereas it was deleted in 1 of 5 (20%) low‐grade glioma samples. These results suggested that inactivation of the CDK4I gene may play an important role in the progression of human glioma. Copyright © 1995, Wiley Blackwell. All rights reserved
  • T. Yamagata, J. Nishida, R. Sakai, T. Tanaka, H. Honda, N. Hirano, H. Mano, Y. Yazaki, H. Hirai  Molecular and Cellular Biology  15-  3830  -3839  1995/01   [Not refereed] [Not invited]  
    Interleukin-5 (IL-5) is produced by T lymphocytes and known to support B- cell growth and eosinophilic differentiation of the progenitor cells. Using ATL-16T cells which express IL-5 mRNA, we have identified a region within the human IL-5 gene promoter that regulates IL-5 gene transcription. This cis- acting sequence contains the core binding motif, (A/T)GATA(A/G), for GATA- binding family proteins and thus suggests the involvement of this family members. In this report, we describe the cloning of human GATA-4 (hGATA-4) and show that hGATA-4 selectively interacts with the -70 GATA site within the IL-5 proximal promoter region. By promoter deletion and mutation analyses, we established this region as a positive regulatory element. Cotransfection experiments revealed that both hGATA-4 and phorbol-12-myristate-13-acetate (PMA)-A23187 stimulation are necessary for IL-5 promoter activation. The requirement for another regulatory element called CLE0, which lies downstream of the -70 GATA site, was also demonstrated. ATL-16T cells express mRNAs of three GATA-binding proteins, hGATA-2, hGATA-3, and hGATA-4, and each of them has a potential to bind to the consensus (A/T)GATA(G/A) motif. However, using ATL-16T nuclear extract, we demonstrated that GATA-4 is the only GATA- binding protein that forms a specific DNA-protein complex with the -70 GATA site. An electrophoretic mobility shift assay with extracts of COS cells expressing GATA-binding proteins showed that GATA-4 has the highest binding affinity for the -70 GATA site among the three GATA-binding proteins. When the transactivation abilities were compared among the three, GATA-4 showed the highest activity. These results demonstrate the selective role of GATA-4 in the transcriptional regulation of the IL-5 gene in a circumstance where multiple members of the GATA-binding proteins are expressed.
  • R. Sakai, A. Iwamatsu, N. Hirano, S. Ogawa, T. Tanaka, J. Nishida, Y. Yazaki, H. Hirai  Journal of Biological Chemistry  269-  32740  -32746  1994/12   [Not refereed] [Not invited]  
    The transforming gene v-crk found in CT10 and ASV-1 avian sarcoma viruses induces marked phosphorylation of several proteins in cells expressing p47(v- crk) (v-Crk). In this work, the main tyrosine-phosphorylated proteins in ASV- 1-infected chicken cells and v-crk-transfected rat cells were characterized biochemically. Both these proteins have a molecular mass of about 130 kDa and are tightly associated with v-Crk in vivo. Two-dimensional gel electrophoresis revealed that they are both essentially single proteins (p130) with modifications that result in a broad spot in an acidic region. The broad band of semi-purified p130 became sharp at an elevated position in the gel upon treatment with orthovanadate in vivo or with c-Src kinase produced using a baculovirus vector in vitro, whereas it shifted at a lower position upon treatment with alkaline phosphatase in vitro. These results suggest multiple phosphorylation states of p130, which result in a broad band of p130. Two procedures of immunoaffinity purification were used to purify p130 from 3Y1 cells transfected with v-crk. Approximately 30 pmol of purified p130 was obtained in an immobilized form on a filter starting from 3 x 10 10 cells. Peptide mapping of p130 digested in situ by peptidase revealed that the purity and quantity of the final material were enough for peptide sequencing. Several stretches of partial amino acid sequences were determined, and they indicated that p130 is a novel protein.
  • Naoto Hirano, Naoto Hirano, Futoshi Shibasaki, Hiroyuki Kato, Ryuichi Sakai, Tomoyuk Tanaka, Tomoyuk Tanaka, Junji Nishida, Yoshio Yazaki, Tadaomi Takenawa, Hisamaru Hirai  Biochemical and Biophysical Research Communications  204-  375  -382  1994/10   [Not refereed] [Not invited]  
    We have isolated bovine phospholipase C (PLC)-α cDNA from bovine thymus. Sequence analysis showed that PLC-α is highly conserved among rat, mouse, and calf and that it has two Trp-Cys-Gly-His-Cys-Lys motifs completely conserved in the mammals. Southern blot analysis revealed that bovine PLC-α is derived from a single gene. When PLC-α cDNA was stably transfected in NIH3T3 cells, there was no increase in PLC activity. PLC-α is supposed to be a member not of PLC superfamily but of Trp-Cys-Gly-His-Cys-Lys motif-containing proteins consisting of protein disulfide isomerase, P5, ERp72, and thioredoxin. PLC-α should be redesignated ERp57 (ER-resided p57). © 1994 Academic Press, Inc.
  • Ryuichi Sakai, Akihiro Iwamatsu, Naoto Hirano, Seishi Ogawa, Tomoyuki Tanaka, Hiroyuki Mano, Yoshio Yazaki, Hisamaru Hirai, Hisamaru Hirai  EMBO Journal  13-  3748  -3756  1994/09   [Not refereed] [Not invited]  
    p47(v-crk) (v-Crk), a transforming gene product containing Src homology (SH)-2 and -3 domains, induces an elevated level of tyrosine phosphorylation of several cellular proteins. Among these proteins, a 125-135 kDa protein (p130) shows marked phosph orylation at tyrosines and tight association with v-Crk, suggesting a direct signal mediator of v-Crk. Here we report the molecular cloning of rat p130 by immunoaffinity purification. The p130 is a novel SH3-containing signaling molecule with a cluster of multiple putative SH2-binding motifs of v-Crk. Immunochemical analyses revealed that p130 is highly phosphorylated at tyrosines during transformation by p60(v-src) (v-Src), as well as by v-Crk, forming stable complexes with these oncoproteins. The p130 behaves as an extremely potent substrate of kinase activity included in the complexes and it is a major v-Src-associated substrate of the Src kinase by partial peptidase mapping. Subcellular fractionation demonstrated that the cytoplasmic p130 could move to the membrane upon tyrosine phosphorylation. The p130 (designated Cas for Crk-associated substrate) is a common cellular target of phosphorylation signal via v-Crk and v-Src oncoproteins, and its unique structure indicates the possible role of p130(Cas) in assembling signals from multiple SH2-containing molecules.
  • Seishi Ogawa, Hideo Toyoshima, Hiroyuki Kozutsumi, Kohichi Hagiwara, Ryuichi Sakai, Tomoyuki Tanaka, Naoto Hirano, Hiroyuki Mano, Yoshio Yazaki, Hisamaru Hirai  Oncogene  9-  1669  -1678  1994/06   [Not refereed] [Not invited]  
    We have isolated the mouse c-crk cDNA from a mouse liver cDNA library. It encodes 304 amino acids and consists mainly of SH2/SH3 regions. In Northern blot analysis, the mouse c-crk mRNA is expressed ubiquitously in every tissue and organ, suggesting that the c-Crk protein may be a common signal transducing molecule among tissues. In contrast to the v-Crk protein, which has a single SH3 domain, the c-Crk protein contains two, the more N-terminal SH3 1 domain and the C-terminal SH3 2 domain. To elucidate functions of these SH3 domains, we have constructed two c-crk mutants, B-crk and D-crk, which lack the SH3 2 and the SH3 1 domain, respectively. These mutants were expressed in rat 3Y1 cells, and examined for their transforming ability in terms of morphological phenotypes and for tyrosine phosphorylation profiles of cells expressing the mutant proteins. Morphological alteration and increased tyrosine phosphorylation of 130-140kDa proteins, the major component of which is the Crk-associated p130, were observed in cells expressing B-Crk as well as those expressing v-Crk, but little in cells expressing c-Crk even at a similar level of expression. Although a highly tyrosine-phosphorylated form of the p130 was coimmunoprecipitated with c-Crk as well as B-Crk, the relative level of tyrosine phosphorylation of the p130, which is normalized to the amount of Crk protein immunoprecipitated, was 10 to 20 times higher in B-Crk-expressing cells than in c-Crk- or D-Crk-expressing cells. The present results indicate that the SH3 2 domain of mouse c-Crk protein negatively regulates tyrosine phosphorylation of the p130, and that lack of the SH3 2 domain in B-Crk and v-Crk may contribute, at least partly, to their morphological alteration or transforming ability through increasing tyrosine phosphorylation of the p130.
  • Michio Namikoshi, Byoung Wook Choi, Ryuichi Sakai, Furong Sun, Kenneth L. Rinehart, Wayne W. Carmichael, William R. Evans, Phillip Cruz, Murray H.G. Munro, John W. Blunt  Journal of Organic Chemistry  59-  2349  -2357  1994/05   [Not refereed] [Not invited]  
    A general method has been developed for assigning the structures of nodularin, a potent hepatotoxin, tumor promoter, and protein phosphatase inhibitor, and minor components isolated from a cultured and a bloom sample of the cyanobacterium Nodularia spumigena. It consists of (1) FABMS analysis (determination of molecular weight and molecular formula), (2) 1 H NMR spectroscopy on the parent compound and chiral GC analysis of an acid hydrolyzate (identification and stereochemistry of amino acid components), (3) ozonolysis followed by NaBH 4 reduction (conversion to a linear peptide), and (4) FABMS/CID/MS analyses of the linear peptide and the parent compound (sequence analysis). The method has been employed in assigning structures to three new nodularins (2–4) and can be applied to other cyclic peptides containing α,β-dehydroamino acid unit(s), especially the related microcystins, cyclic heptapeptide hepatotoxins. Two nodularins, [DMAdda 3 ]nodularin (2) and [(6Z)- Adda 3 ]nodularin (3), were obtained from a bloom sample collected from Lake Ellesmere (New Zealand), and [D-Asp 1 ]nodularin (4) was isolated from cultured cells (strain L-575). The LD50s of 2 and 4 were 150 and 75 μg/kg (ip, mice), respectively, but 3 did not show apparent toxicity at 2.0 mg/kg. © 1994, American Chemical Society. All rights reserved.
  • Elizabeth A. Jares-Erijman, Chintamani P. Bapat, Anna Lithgow-Bertelloni, Kenneth L. Rinehart, Ryuichi Sakai  Journal of Organic Chemistry  58-  5732  -5737  1993/01   [Not refereed] [Not invited]  
    Crucigasterins 277, 275, and 225, three new polyunsaturated amino alcohols, 10–12, were isolated from the Mediterranean tunicate Pseudodistoma crucigaster. The structures of these compounds were assigned based on NMR and FABMS data. Absolute stereochemistry of the amino alcohol portion in 10 was assigned to be 2R,3S based on chiral GC comparison of 3-hydroxy-4-aminopentanoic acid 13d, a chemical degradation product of 10, with a synthetic sample prepared from l-alanine. Compounds 10–12 exhibited moderate cytotoxicity and antimicrobial activity. © 1993, American Chemical Society. All rights reserved.
  • Elizabeth A. Jares-Erijman, April L. Ingrum, John R. Carney, John R. Carney, Kenneth L. Rinehart, Ryuichi Sakai  Journal of Organic Chemistry  58-  4805  -4808  1993/01   [Not refereed] [Not invited]  
    The absolute stereochemistry of the pentacyclic guanidine moieties of crambescidin 816 (1) 1 and of 13,14,15-isocrambescidin 800 (4), a new member of this family, was determined, based on chiral GC analysis of a derivative of 2-hydroxybutanoic acid, an ozonolysis product of the crambescidins. Significantly less antiviral activity and cytotoxicity were observed for 4. © 1993, American Chemical Society. All rights reserved.
  • R. Sakai, K. L. Rinehart, Y. Guan, A. H J Wang  Proceeding of National Academy of Science U. S. A.  89-  (89)  11456  -11460  1992/12   [Not refereed] [Not invited]  
    Ecteinascidins (Ets), isolated from the Caribbean tunicate Ecteinascidia turbinata, protect mice in vivo against P388 lymphoma, B16 melanoma, M5076 ovarian sarcoma, Lewis lung carcinoma, and the LX-1 human lung and MX-1 human mammary carcinoma xenografts. Crystal structures of two tris(tetrahydroisoquinoline) Ets were investigated with single crystals of the 21-O-methyl-N 12 -formyl derivative of Et 729 and the natural N 12 -oxide of Et 743. Representatives of an additional class of Ets, Et 722 and Et 736, isolated from the same organism, were assigned tetrahydro-β-carboline- substituted bis(tetrahydroisoquinoline) structures by NMR and fast atom bombardment MS spectra.
  • Tomoyuki Tanaka, Futoshi Shibasaki, Masaharu Ishikawa, Naoto Hirano, Naoto Hirano, Ryuichi Sakai, Junji Nishida, Tadaomi Takenawa, Hisamaru Hirai, Hisamaru Hirai  Biochemical and Biophysical Research Communications  187-  1022  -1028  1992/09   [Not refereed] [Not invited]  
    Actins are major cytoskeletal components and highly conserved in evolution. In mammals, there are six actin isoforms, a pair of which shows at least 93% identity in the amino acid sequence. We have cloned cDNA for a bovine protein that is distantly related to members of the mammalian actin isotypes. The predicted amino acid sequence (418 residues long, calculated molecular mass 47369) shows that this protein, which we have named actin2, exhibits 36% identity to mammalian actins and 60% identity to the yeast actin-like protein, act2. We have concluded that actin2 defines a new class of mammalian actin-like proteins. It was also revealed that actin2 messenger RNA is expressed in a broad range of tissues. © 1992.
  • Koichi Sugimoto, Hideo Toyoshima, Ryuichi Sakai, Kiyoshi Miyagawa, Koichi Hagiwara, Fuyuki Ishikawa, Furnimaro Takaku, Yoshio Yazaki, Hisamaru Hirai  Blood  79-  2378  -2383  1992/05   [Not refereed] [Not invited]  
    The p53 gene is currently considered to function as a tumor-suppressor gene in various human malignancies. In hematologic malignancies, alterations in the p53 gene have been shown in some human leukemias and lymphomas. Although mutations in the p53 gene are infrequent in acute myelogenous leukemia (AML) patients, we show in this report that alterations in the p53 gene are frequent in myeloid leukemia cell lines. We studied alterations of the p53 gene in nine human myeloid leukemia cell lines by reverse transcriptase-polymerase chain reaction (RT-PCR), single-strand conformation polymorphism (SSCP) analysis, and direct sequencing. Expression of the p53 gene was not detected at all by RT-PCR in two of the nine cell lines. In these two cell lines, Southern blot analysis showed gross rearrangements and deletions in both of the p53 alleles. Six of the nine cell lines were found to express only mutant p53 mRNA by RT-PCR/SSCP analysis and direct sequencing, and wild-type p53 mRNA was not detected. Two of the mutant p53 mRNAs were shown to be products of abnormal splicing events induced by intronic point mutations. Taken together, eight of nine human myeloid leukemia cell lines expressed no or an undetectable amount of wild-type p53 mRNA. Three of the eight cell lines were growth factor-dependent. Our results suggest that inactivation of the p53 gene may be a common feature in myeloid leukemia cell lines and may play an important role in the establishment of these cell lines. © 1992 by The American Society of Hematology.
  • Kenneth L. Rinehart, Ryuichi Sakai, Vimal Kishore, David W. sullins, Kai ming Li  Journal of Organic Chemistry  57-  3007  -3013  1992/05   [Not refereed] [Not invited]  
    The eight possible stereoisomers of isostatine, (3S,4P,5S)-4-amino-3-hydroxy-5-methylheptanoic acid, have been synthesized from the four isomeric d- and l-isoleucinals and d- and l-allo-isoleucinals and ethyl lithioacetate. The eight isomers have been compared for the GC retention times of their bis(trifluoroacetyl) methyl ester derivatives and the 1 H NMR properties of the γ-lactams derived from them. The natural isomer was shown to be the 3S,4R,5S isomer. © 1992, American Chemical Society. All rights reserved.
  • Michio Namikoshi, Kenneth L. Rinehart, Ryuichi Sakai, Richard R. Stotts, Andrew M. Dahlem, Val R. Beasley, Wayne W. Carmichael, William R. Evans  Journal of Organic Chemistry  57-  866  -872  1992/01   [Not refereed] [Not invited]  
    Eleven minor components were isolated, together with microcystin-LR (LR, 1, Scheme I) as the principal toxin (ca. 90% of the toxic components), from Microcystis cyanobacteria (blue-green algae) collected from Homer Lake (Illinois) in the summer of 1988. The components were characterized by amino acid analysis and HRFABMS, FABMS/MS, 1 H NMR, and UV spectroscopic methods as microcystins-RR (2) and -YR (3) (Scheme I) and nine new microcystins. The structures of seven new microcystins were assigned as [DMAdda 5 ]microcystin-LR (4), [Dha 7 ]microcystin-LR (5), microcystin-FR (6), microcystin-AR (7), microcystin-M(O)R (8), [Mser 7 ]microcystin-LR (9), and microcystin-WR (12). Compound 4 is the first microcystin containing 9-O-demethyl-Adda, while phenylalanine, N-methylserine, and tryptophan are also new variations in amino add components of microcystins. Compound 11 was deduced to be a (C 3 H 7 O) monoester of the α-carboxyl on the Glu unit of LR (1). New microcystin 11 caused no apparent toxic effects in mice dosed ip at 1 mg/kg, while the others had LD 50 's of 90–800 µg/kg. © 1992, American Chemical Society. All rights reserved.
  • Elizabeth A. Jares-Erijman, Ryuichi Sakai, Kenneth L. Rinehart  Journal of Organic Chemistry  56-  5712  -5715  1991/09   [Not refereed] [Not invited]
  • Koichi Sugimoto, Koichi Sugimoto, Hideo Toyoshima, Ryuichi Sakai, Kiyoshi Miyagawa, Koichi Hagiwara, Hisamaru Hirai, Fuyuki Ishikawa, Fumimaro Takaku  Blood  77-  1153  -1156  1991/03   [Not refereed] [Not invited]  
    p53 is currently considered to be a tumor suppressor gene product, and its alterations are suggested to be involved in several human malignancies. Here we show evidence of the possible involvement of p53 gene mutations in lymphoid leukemias studied by reverse transcriptase-polymerase chain reaction, single strand conformation polymorphism analysis, and nucleotide sequencing. Fourteen patients with various leukemias were examined and two with acute lymphoblastic leukemia and one with Waldenström's macroglobulinemia were identified to have mutations in the coding region of the p53 gene. These mutations included point mutation, triplet deletion, and single nucleotide insertion. Furthermore, expression of the wild-type p53 mRNA was not detected in the samples from these three patients. In one of them, chromosome 17p was deleted, suggesting the absence of the nonmutated p53 gene, whereas in the other two patients, chromosome 17p seemed to be intact by cytogenetic analysis. Our results suggest that alterations of the p53 gene may have a role in the genesis of some leukemias. © 1997 by The American Society of Hematology.
  • Gang‐Hong ‐H Lee, Ryuichi Sakai, Minako Nagao, Tomoyuki Kitagawa  International Journal of Cancer  47-  60  -65  1991/01   [Not refereed] [Not invited]  
    The nature of 15 immortal mouse liver epithelial cell (MLEC) lines established from normal C3H mice was investigated specifically in terms of ras oncogene activation. Neither transforming activity nor point mutation within codon 61 of c‐H‐ras could be demonstrated in any of the cell lines by DNA transfection in a NIH/3T3 cell system or by the direct sequencing method after polymerase chain reaction, respectively. Acrylamide gel migration analysis of ras p2l products did not show any shift from the normal. Transplantation experiments demonstrated only 2 out of the 15 lines to be tu‐morigenic in nude mice. When 4 of the non‐tumorigenic MLEC lines were transfected with cloned activated c‐H‐ras containing a point mutation within codon 61, they all became tumorigenic, the resultant neoplasms being hepatocellular carcinomas often associated with albumin mRNA expression. Our results thus indicate that ras activation is not necessary for immortalization or even for transformation of mouse liver cells in culture, and that ras activation may be an event during the progression process in mouse hepatocarcinogene‐sis in vivo. Copyright © 1991 Wiley‐Liss, Inc., A Wiley Company
  • Toshikazu Ushijima, Masahiro Tsutsumi, Masahiro Tsutsumi, Ryuichi Sakai, Ryuichi Sakai, Yukihito Ishizaka, Fumimaro Takaku, Fumimaro Takaku, Yoichi Konishi, Yoichi Konishi, Michihito Takahashi, Michihito Takahashi, Takashi Sugimura, Minako Nagao  Japanese Journal of Cancer Research  82-  965  -968  1991/01   [Not refereed] [Not invited]  
    Five pancreatic carcinomas induced by N‐nitrosobis(2‐hydroxypropyl)amine in Syrian golden hamsters were analyzed for activation of Ki‐ras at codons 12 and 13, using the polymerase chain reaction and direct sequencing. The Ki‐ras gene was shown to be activated in four of the five carcinomas, and the results were further confirmed by subcloning and sequencing. All the mutations involved a G‐to‐A transition at the second position of codon 12, which resulted in a change at the amino acid level from glycine to aspartic acid. This mutation is identical with that reported for pancreatic tumors of Syrian hamsters induced by N‐nitrosobis(2 ‐oxopropyl)amine. Copyright © 1991, Wiley Blackwell. All rights reserved
  • T. Tahira, M. Shiraishi, M. Shiraishi, Y. Ishizaka, I. Ikeda, R. Sakai, T. Sugimura, M. Nagao  Nucleic Acids Research  18-  7472  1990/12   [Not refereed] [Not invited]
  • Michio Namikoshi, Kenneth L. Rinehart, Ryuichi Sakai, Kaarina Sivonen, Wayne W. Carmichael  Journal of Organic Chemistry  55-  6135  -6139  1990/01   [Not refereed] [Not invited]  
    Three new hepatotoxic cyclic heptapeptides in the microcystin class were isolated from the cyanobacterium (blue-green alga) Nostoc sp. strain 152 and assigned structures based on their high-resolution FABMS, FABMS/MS, 1 H and 13 C NMR spectra, amino acid analysis, and GC on a chiral capillary column. All three toxins (1–3) have 9-acetoxy-3-amino-2,6,8-trimethyl-10-phenyl-4,6-decadienoic acid as an unusual structural component (Scheme I) instead of the corresponding 9-methoxyl derivative (Adda) found in the microcystins. © 1990, American Chemical Society. All rights reserved.
  • M. Nagao, R. Sakai, Y. Kitagawa, I. Ikeda, K. Sasaki, H. Shima, T. Sugimura  Princess Takamatsu symposia  20-  177  -184  1989/12   [Not refereed] [Not invited]  
    Many oncogene products are protein kinases and signals are transduced via phosphorylation of proteins. Similarly, protein-dephosphorylation may play a critical role in malignant cell transformation. We have cloned two catalytic subunits of ser/thr protein phosphatase (PP) type 2A, PP2A alpha, and PP2A beta, from a rat liver cDNA library. Both cDNAs encode peptides of 309 amino acids with a difference of only 8 amino acids between the two. All primary hepatocellular hyperplastic nodules or carcinomas, which were induced by a food carcinogen, 2-amino-3-methylimidazo[4,5-f]quinoline, showed up-regulation of expression of the mRNAs of both PP2A alpha and PP2A beta. NIH3T3 cell transformants obtained by introducing activated c-raf, ret-II or Ki-ras oncogenes also showed high levels of PP2A alpha transcripts. Okadaic acid, a non-TPA type tumor promoter, was found to be a potent inhibitor of PP1 and PP2A. Its IC50 for PP1 was much higher than that for PP2A with phosphorylase a as a substrate. When raf and ret-II transformants were cultured with okadaic acid at 8 ng/ml for 2 days, both transformants became flattened and showed strict contact inhibitions. This flat cell morphology was stable for at least one month in the presence of okadaic acid, but in its absence, the cells reverted to their original transformed shape within 7-10 days. Colony formation by raf and ret-II transformants in soft agar was inhibited dose-dependently by okadaic acid; very few colonies grew in the presence of the acid at 8 ng/ml. Okadaic acid had less effect on a transformant of the Ha-ras gene, causing only 50% inhibition of colony formation at 8 ng/ml. The role of protein phosphatases in cellular transformation by certain oncogenes is suggested.
  • R. Sakai, I. Ikeda, H. Kitani, H. Fujiki, F. Takaku, U. Rapp, T. Sugimura, M. Nagao  Proceedings of the National Academy of Sciences of the United States of America  86-  9946  -9950  1989/12   [Not refereed] [Not invited]  
    Okadaic acid is a non-phorbol 12-myristate 13-acetate (PMA)-type tumor promoter on mouse skin and known to be a potent inhibitor of serine/threonine protein phosphatases. Contrary to expectation from its tumor-promoting activity, okadaic acid was shown to have a potential to revert the phenotype of cells transformed by raf and ret-II to that of normal cells. Two to 3 days after addition of 8 ng of okadaic acid per ml to the culture medium, raf and ret-II transformants changed to flat cells and gained contact inhibition. The amount of fibronectin, which was decreased in malignant transformed cells, was increased in the flat revertants. Moreover, okadaic acid caused a dose-dependent loss of ability to grow in soft agar. The morphology of the cells reverted to malignant phenotype within 1 week after removal of okadaic acid. The levels of mRNA and protein of activated c-raf in flat revertants were similar to those in parental transformed cells. The level of mRNA of ret-II was also not changed by flat reversion. No induction of flat reversion was observed with okadaic acid tetramethyl ether, an inactive compound, or a phorbol ester, PMA. As okadaic acid is a potent inhibitor of protein phosphatases 1 and 2A, the possibility that these phosphatases are involved in signal transduction from the raf and ret-II oncogenes is suggested.
  • Yoshinori Kitagawa, Ryuichi Sakai, Tomoko Tahira, Hiroyuki Tsuda, Nobuyuki Ito, Takashi Sugimura, Minako Nagao  Biochemical and Biophysical Research Communications  157-  821  -827  1988/12   [Not refereed] [Not invited]  
    A cDNA clone coding for an isotype of the catalytic subunit of rat phosphoprotein phosphatase 2A was isolated. The deduced amino acid sequence of the clone was different at 8 positions from that of rat phosphatase 2Aα determined in a previous study. The deduced amino acid sequence of the clone was, however, identical to that of human phosphatase 2Aβ and differed only at one position from that of rabbit 2Aβ. Thus, the isolated cDNA was identified as a clone coding for rat phosphatase 2Aβ. Using a 2Aβ specific probe, two kinds of transcripts were detected in rat liver: a major 2.0 kb mRNA transcript and a minor 1.4 kb mRNA transcript. These transcripts were both greatly increased in rat liver tumors induced by 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) regardless of the carcinoma or hyperplastic nodule. © 1988 Academic Press, Inc.
  • F. Ishikawa, R. Sakai, M. Ochiai, T. Sugimura, M. Nagao  Nucleic acids symposium series  39  -42  1988/12   [Not refereed] [Not invited]  
    Activation mechanism of raf oncogene was studied by applying in vitro mutagenesis to its cDNA. Previous studies suggested the presence of an activation suppressing sequence in the amino-terminal half of c-raf product. Loss of the sequence by genetic rearrangement was presumed to convert c-raf to possess transforming activity. To identify such sequence, we prepared cDNA mutants by random linker insertion. Synthetic oligonucleotide linker was inserted into the plasmid containing cDNA at a single and random site. Coupling two different mutants, in-frame deletion mutants were constructed systematically. Analysis of these deletion mutants revealed a region, the loss of which made c-raf activated.
  • F. Ishikawa, R. Sakai, M. Ochiai, F. Takaku, T. Sugimura, M. Nagao  Oncogene  3-  653  -658  1988/12   [Not refereed] [Not invited]  
    Our previous study revealed that the rat c-raf was activated by a rearrangement leading to replacement of the amino-terminal half of the product. Therefore, we suggested that some sequences present in the amino-terminal half might prevent c-raf from becoming an active oncogene. To examine this possibility, we constructed a series of deletion mutants of c-raf cDNA by the random linker insertion method. By transfection of NIH3T3 cells with these mutants, a region whose deletion resulted in activation of c-raf was identified. This region is located at amino acid residues 245 to 261, immediate upstream of the kinase domain of the c-raf product and is rich in serine and threonine residues. This region includes a sequence of six amino acids, RSTSTP, which is conserved in the products of normal raf gene families of various species. This sequence is the best candidate for suppressing transforming activity of c-raf.
  • Nigel B. Perry, John W. Blunt, Murray H.G. Munro, Tatsuo Higa, Ryuichi Sakai  Journal of Organic Chemistry  53-  4127  -4128  1988/08   [Not refereed] [Not invited]
  • Toshio Ichiba, Ryuichi Sakai, Shigeo Kohmoto, Gabriel Saucy, Tatsuo Higa  Tetrahedron Letters  29-  3083  -3086  1988/01   [Not refereed] [Not invited]  
    Manzamines E (2) and F (3) have been isolated as cytotoxic constituents of a sponge of the genus Xestospongia and the structures elucidated by the application of 2D-NMR tecniques and spectroscoplc comparison with manzamine A (1). Manzamine F was shown to be identical with keramamine B (4), the structure of which should therefore be revised as 3. © 1988.
  • Isuzu Ikeda, Yukihito Ishizakz, Masako Ochiai, Ryuichi Sakai, Masayuki Itabashi, Masahiko Onda, Takashi Sugimura, Minako Nagao  Japanese Journal of Cancer Research  79-  674  -676  1988/01   [Not refereed] [Not invited]  
    The correlations of the restriction fragment length polymorphism (RFLP) pattern of L‐myc with the progressive state of cancer and metastases to lymph nodes or other organs were examined in 35 cases of human colorectal cancer by χ 2 analysis. No significant correlation was found. Copyright © 1988, Wiley Blackwell. All rights reserved
  • Kato Yuko, Fusetani Nobuhiro, Matsunaga Shigeki, Hashimoto Kanehisa, Sakai Ryuichi, Higa Tatsuo, Kashman Yoel  天然有機化合物討論会講演要旨集  0-  (29)  301  -308  1987/07   [Not refereed] [Not invited]  
    During the course of our search for bioactive metabolites from Japanese marine invertebrates, we found that methanol extract of a sponge Theonella sp. collected in Hachijo-jima island revealed strong activity both in the echinoderm egg assay and in the cytotoxicity test. Fran this sponge we have isolated two active components, named bistheonellides A and B (1 and 2, respectively), which inhibited development of starfish embryos at 0.1 and 0.2μg/ml, respectively as well as growth of tumor cells at low concentrations. Bistheonellide A exhibited spectral data, except for molecular weight, iden...
  • Kenneth L. Rinehart, Vimal Kishore, Srinivasan Nagaraian, Robin J. Lake, James B. Guylploer, Frank A. Bozich, Kai Ming Li, Robert E. Maleczka, William L. Todsen, Murray H.G. Munro, David W. Sullins, Ryuichi Sakai  Journal of the American Chemical Society  109-  6846  -6848  1987/10   [Not refereed] [Not invited]
  • Ryuichi Sakai, Ryuichi Sakai, Shigeo Kohmoto, Shigeo Kohmoto, Tatsuo Higa, Tatsuo Higa, Charles W. Jefford, Gérald Bernardinelli  Tetrahedron Letters  28-  5493  -5496  1987/01   [Not refereed] [Not invited]  
    The title compounds were isolated from a marine sponge collected off Okinawa. Their structures were determined by X-ray and shown to be 1-β-carbolines. Manzamine C was the 2-ethyl-N-azacycloundec-6-ene derivative, whereas manzamine B was more complex being the epoxy isomer of the free base of dihydromanzamine A. © 1987.
  • Yuko Kato, Nobuhiro Fusetani, Shiegeki Matsunaga, Kaneshisa Hashimoto, Ryuichi Sakai, Tatsuo Higa, Yoel Kashman  Tetrahedron Letters  28-  6225  -6228  1987/01   [Not refereed] [Not invited]  
    Two antitumor macrodiolides, bistheonellides A and B, were isolated from a marine sponge Theonella sp. Bistheonellide A was found to be identical with misakinolide A, whose structure has been revised from the previously proposed monomeric macrolide (3) to the dimeric macrodiolide (1). Similarly, bistheonellide B was deduced to be the related structure 2. © 1987.
  • 酒井 隆一, 比嘉 辰雄  Bulletin of the College of Science,University of the Ryukyus  (36)  p99  -104  1983/09   [Not refereed] [Not invited]
  • 阿波島清, 井上理人, 岡本静江, 酒井隆一, 柳瀬彦三  南大阪病院医学雑誌  29-  (2/3)  212  -215  1981/12   [Not refereed] [Not invited]
  • W. Mori, H. Asakawa, T. Taguchi, R. Sakai  Acta Haematologica Japonica  41-  1309  -1317  1978/12   [Not refereed] [Not invited]  
    Our recent studies on ferritin have revealed, at least, two interesting points concering its close relation to malignant neoplasms; frequent elevation of ferritin level in cancer patients' serum, and existence of biochemical as well as immunological heterogeneities between several isoferritins of human origin. The former indicates some possibility of its usefulness as a laboratory test for cancer diagnosis, and the latter suggests indispensable necessity of selection of the most suitable human isoferritin as the material for the test. Our tentative conclusion at present is that human placental ferritin seems to be the most suitable material for producing the antiserum to be used for the test of cancer diagnosis from various points of view, our studies therefore have been carried out mainly using anti-human placental ferritin antiserum. In such a way we have obtained some meaningful results on the ferritin test of patients' serum, which we would like to review with some other, more fundamental data on human ferritin, very briefly here in this paper. A short discussion including future problems in this field of study is also to be made at the conclusion.
  • Journal of Americium Chemical Society  (117)  1995   [Not refereed] [Not invited]
  • Journal of American Chemical Society  (108)  1986   [Not refereed] [Not invited]
  • Bioorg. Med. Chem. Lett.  10-  (16)  1787  -1789  2000   [Not refereed] [Not invited]
  • Pharmacological properties of the potent epileptogenic amino acid dysiherbaine, a novel Glutamate receptor agonist isolated from the marine sponge dysidea herbacea
    Journal of Pharmacology and experimental therapeutics  296-  (2)  650  -658  2001   [Not refereed] [Not invited]
  • Organic letters  3-  (10)  1479  -1482  2001   [Not refereed] [Not invited]

Research Grants & Projects

  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(基盤研究(C))
    Date (from‐to) : 2007 -2009 
    Author : Yasushi SHIGERI
    独立行政法人産業技術総合研究所Alanine-serine-cysteine transporters (ASCT1, 2) are neutral amino acids transporters. Their representative substrates are alanine, serine and cysteine. Since th ere is no specific inhibitors or substrates for ASCT1 and ASCT2, their physiological functions are quite mystery. To develop their specific compounds to modulate their functions, high-throughput screening is essential. Therefore, we made two approaches as follows. First, we looked for host cells with lower level of endogenous ASCT1 or ASCT2. We checked CHO cells, HEK293 cells, 3T3 cells and other cells. But all of the cells that we ...
  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(基盤研究(B))
    Date (from‐to) : 2005 -2007 
    Author : Ryuichi SAKAI
    北里大学In the present study, we identified new polyamines from a Okinawan sponge Axinissa aculeate that modulate ligand binding to NMDA type glutamate receptors. These polyamines may also function as a factor involved in silica biomineralization in the sponge. From the same extract, we identified new peptides containing polyamine in the substructure and named aculeines. This novel highly modified peptide showed strong convulsant actions in mice. We also isolated Cribropurine, a new purine from a Micronesian sponge Chribrocharina olemda. Cribroprine elicited a seizure-like spontaneous current in ra...
  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(基盤研究(B))
    Date (from‐to) : 2003 -2005 
    Author : Hisao KAMIYA
    北里大学The D-galactose-binding lectin, Sll-2, in the octocoral was effectively purified by affinithy chromatography on D-galactosamine-HiTrap column using Tris-HCl buffer containing 0.5% L-ascorbic acid and 0.1% kojic acid to avoid melanization and insolubilization of SLL-2 during purification. The purified SLL-2 gave many spot in 2D-PAGE with different pI values rangin from 3 to 5. However, after the N-glycopeptidase F treatment, the molecular weight of subunit (16.5kDa) reduced to 9.5kDa with three different pIs. These results suggested that SLL-2 is a mixture of isolectins composed of three gly...
  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(基盤研究(C))
    Date (from‐to) : 2003 -2004 
    Author : Ryuichi SAKAI
    北里大学We have investigated the cellular localization of the marine sponge-derived excitatory amino acid dysiherbaine (DH), and found that DH-like immunoreactivity was densely located in the large (10 μm) globular cells. On the basis of 18S rDNA sequence analysis it was shown that this cell belongs to the sponge itself, however, results from fluorescent microscopy and immunohistochemistry using anti-phycobilin antibody indicated that this cell contains phycobilin, a photosynthetic pigment of cyanobacteria. Although number of histological observations of D.herbacea are available in literature, cell...
  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(基盤研究(B))
    Date (from‐to) : 2000 -2003 
    Author : Shigeru SATO
    北里大学Although many sophisticated analyzing methods for paralytic shellfish toxins (PSP toxins) have been developed, mouse bioassay is still applied as official method for monitoring of bivalve toxicity in various countries including Japan. Mouse bioassay is a simple and reliable method, but many problems about animal experiments have been pointed out for this method. Currently a simple and rapid method which could be replaceable with mouse bioassay is needed. ELISA far PSP toxins is one of the first candidates. In order to make specific antibody against toxins required for ELISA, hapten antigen ...
  • Ministry of Education, Culture, Sports, Science and Technology:Grants-in-Aid for Scientific Research(基盤研究(B))
    Date (from‐to) : 2000 -2002 
    Author : Hisao KAMIYA
    北里大学The cDNA cloning of SLL-2, a D-galactose-binding lectin of the octocoral Sinularia lochmodes, has revealed that SLL-2 had a sequence homology to those of "discoidin" group lectins. It is observed that the difference of 2 kD in the molecular weight of SLL-2 was present between that calculated from the deduced amino acid sequence of SLL-2 (10, 751) and that observed in SDS-PAGE(15, 000) and TOF-MS (13, 194). No neutral sugar was observed. On the other hand, the spectroscopic analysis and also a treatment with tyrosinase suggested the presence of dopa in a lectin molecule. SLL-2 seems to have ...
  • Isolation and structure determination of Bioactive Marine natural products.

Educational Activities

Teaching Experience

  • Environment and People
    開講年度 : 2017
    課程区分 : 学士課程
    開講学部 : 全学教育
    キーワード : 生物資源,資源利用,機能性,マリンバイオマス,環境保全,マリンバイオテクノロジー,有効利用,高度利用
  • Natural Product Chemistry
    開講年度 : 2017
    課程区分 : 学士課程
    開講学部 : 水産学部
    キーワード : 生理活性物質 2次代謝物 海洋天然物 天然毒 生合成 ポリケチド イソプレノイド アルカロイド ペプチド
  • Environment and People
    開講年度 : 2017
    課程区分 : 学士課程
    開講学部 : 全学教育
    キーワード : 海、河川、生命、細胞、遺伝子、魚、海藻、微生物、代謝、進化

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