研究者情報

マスター

アカウント（マスター）

• 氏名

  水谷　龍明(ミズタニ　タツアキ), ミズタニ　タツアキ

所属（マスター）

• 医学研究院　生理系部門　生理学分野

所属（マスター）

• 医学研究院　生理系部門　生理学分野

researchmap

プロフィール情報

所属

• 北海道大学, 医学研究院　細胞生理学教室, 講師

学位

• 博士（東京大学）

プロフィール情報

• 姓

  水谷, ミズタニ

• 名

  龍明, タツアキ

• ID各種

  201401032621914569

所属

• 北海道大学, 医学研究院　細胞生理学教室, 講師

業績リスト

研究キーワード

• 腫瘍免疫   好中球   マクロファージ   血液腫瘍   赤血球   GFPイメージング   FRET   結晶構造解析   

研究分野

• ライフサイエンス / 免疫学
• ライフサイエンス / 細胞生物学
• ライフサイエンス / 腫瘍生物学
• ライフサイエンス / 分子生物学
• ライフサイエンス / 実験動物学
• ライフサイエンス / 実験病理学
• ライフサイエンス / 構造生物化学
• ライフサイエンス / 病態医化学

経歴

• 2023年12月 - 現在 北海道大学 医学研究院 細胞生理学教室 講師
• 2022年04月 - 2023年11月 京都大学医生物学研究所 細胞制御分野 助教
• 2017年01月 - 2022年03月 京都大学ウイルス・再生医科学研究所 細胞制御分野 助教
• 2014年07月 - 2016年12月 京都大学ウイルス研究所 細胞制御分野 助教
• 2013年02月 - 2014年06月 長崎大学 創薬教育研究センター 助教
• 2010年05月 - 2013年02月 ルードヴィッヒ・ボルツマン癌研究所 ポスドク研究員
• 2007年04月 - 2010年05月 北海道大学 大学院医学研究科 ポスドク研究員

学歴

• 2003年04月 - 2007年03月   東京大学   大学院医学系研究科   病因・病理学専攻
• 2001年04月 - 2003年03月   東京大学   大学院理学系研究科   生物化学専攻
• 1996年04月 - 2001年03月   東京工業大学   生命理工学部   生体機構学科

論文

• Neutrophil S100A9 supports M2 macrophage niche formation in granulomas

  Tatsuaki Mizutani, Toshiaki Ano, Yuya Yoshioka, Satoshi Mizuta, Keiko Takemoto, Yuki Ouchi, Daisuke Morita, Satsuki Kitano, Hitoshi Miyachi, Tatsuaki Tsuruyama, Nagatoshi Fujiwara, Masahiko Sugita

  iScience 106081 - 106081 2023年01月
• Crystal structures of N-myristoylated lipopeptide-bound HLA class I complexes indicate reorganization of B-pocket architecture upon ligand binding

  Minori Asa, Daisuke Morita, Jin Kuroha, Tatsuaki Mizutani, Naoki Mori, Bunzo Mikami, Masahiko Sugita

  Journal of Biological Chemistry 298 7 102100 - 102100 2022年07月
• Identification of novel chemical compounds targeting filovirus VP40-mediated particle production

  Shuzo Urata, Olaposi Idowu Omotuyi, Ayako Izumisawa, Takeshi Ishikawa, Satoshi Mizuta, Yasuteru Sakurai, Tatsuaki Mizutani, Hiroshi Ueda, Yoshimasa Tanaka, Jiro Yasuda

  Antiviral Research 199 105267 - 105267 2022年02月
• Crystal structure of the ternary complex of TCR, MHC class I, and lipopeptides.

  Daisuke Morita, Chieri Iwashita, Tatsuaki Mizutani, Naoki Mori, Bunzo Mikami, Masahiko Sugita

  International immunology 32 12 805 - 810 2020年07月28日 [査読有り][通常論文]
   

  The covalent conjugation of a 14-carbon fatty acid (myristic acid) to the N-terminal Gly residue, termed N-myristoylation, occurs in some viral proteins to dictate their pathological function. This protein lipidation reaction, however, is monitored by host cytotoxic T-lymphocytes that are capable of recognizing N-terminal lipopeptide fragments in the context of MHC class I molecules. In a rhesus model of human AIDS, for example, the classical MHC class I allomorph, Mamu-B*05104, was shown to bind SIV Nef-derived 4-mer lipopeptides (Myristic acid-Gly-Gly-Ala-Ile; C14nef4) and present them to the CD8+ T cell line, SN45. These lipopeptides accommodated in MHC class I molecules expose much shorter peptide chains than conventional MHC class I-presented 8-10-mer peptides, and the molecular mechanisms by which αβ TCRs recognize lipopeptides currently remain unclear. An X-ray crystallographic analysis of the SN45 TCR α and β heterodimer in a form that was co-crystallized with the C14nef4-bound Mamu-B*05104 complex indicated that the amide group of the N-myristoylated glycine residue offered a primary T-cell epitope by establishing a sole hydrogen bond between its nitrogen atom and the side chain of Glu at position 101 of CDR3β. Accordingly, the Glu to Ala mutation at this position resulted in the loss of lipopeptide recognition. On the other hand, TCRs were positioned remotely from the peptide portion of C14nef4, and strong interactions were not observed. Thus, these observations provide novel structural insights into lipopeptide recognition by TCRs, which contrast sharply with the general molecular principle of peptide recognition.
• Crystal structures of lysophospholipid-bound MHC class I molecules.

  Yoko Shima, Daisuke Morita, Tatsuaki Mizutani, Naoki Mori, Bunzo Mikami, Masahiko Sugita

  The Journal of biological chemistry 295 20 6983 - 6991 2020年04月08日 [査読有り][通常論文]
   

  Newly synthesized major histocompatibility complex (MHC) class I proteins are stabilized in the endoplasmic reticulum (ER) by binding 8- to 10-mer-long self-peptide antigens that are provided by transporter associated with antigen processing (TAP). These MHC class I:peptide complexes then exit the ER and reach the plasma membrane, serving to sustain the steady state MHC class I expression on the cell surface. A novel subset of MHC class I molecules that preferentially bind lipid-containing ligands rather than conventional peptides was recently identified. The primate classical MHC class I allomorphs, Mamu-B*098 and Mamu-B*05104, are capable of binding the N-myristoylated 5-mer (C14-Gly-Gly-Ala-Ile-Ser) or 4-mer (C14-Gly-Gly-Ala-Ile) lipopeptides derived from the N-myristoylated SIV Nef protein, respectively, and of activating lipopeptide antigen-specific cytotoxic T lymphocytes. We herein demonstrate that Mamu-B*098 samples lysophosphatidylethanolamine and lysophosphatidylcholine containing up to a C20 fatty acid in the ER. The X-ray crystal structures of Mamu-B*098 and Mamu-B*05104 complexed with lysophospholipids at high resolution revealed that the B and D pockets in the antigen-binding grooves of these MHC class I molecules accommodate these lipids through a mono-acyl glycerol moiety. Consistent with the capacity to bind cellular lipid ligands, these two MHC class I molecules did not require TAP function for cell-surface expression. Collectively, these results indicate that peptide- and lipopeptide-presenting MHC class I subsets use distinct sources of endogenous ligands.
• An antiviral drug screening platform with a FRET biosensor for measurement of arenavirus Z assembly

  Tatsuaki Mizutani, Yusuke Ohba, Satoshi Mizuta, Jiro Yasuda, Shuzo Urata

  Cell Structure and Function 45 2 155 - 163 2020年 [査読有り]
   

  The smallest arenavirus gene product, Z protein, plays critical roles in the virus life cycle. Z is the major driving force of budding and particle production because of a unique property that defines self-assembly. In addition to the roles in budding, Z also participates in the suppression of type I interferon production to evade host antiviral immunity. Therefore, Z and its assembled form are an attractive drug target for arenaviral hemorrhagic fever, such as Lassa fever. Here, we developed a biosensor that enabled the evaluation of the prototype arenavirus, lymphocytic choriomeningitis virus (LCMV), Z assembly using the principle of Förster resonance energy transfer (FRET). This FRET biosensor consisted of three tandem Z that were sandwiched between super-enhanced cyan-emitting fluorescent protein and variant of a yellow-emitting mutant of green fluorescent protein so that Z-Z intermolecular binding via the really interesting new gene finger domain increased the emission ratio. To identify novel anti-arenavirus compounds, the FRET biosensor was employed to screen the PathogenBox400 for inhibitors of Z assembly in a 96-well plate format. The assay performed well, with a Z'-factor of 0.89, and identified two compounds that decreased the emission ratio of the FRET biosensor in a dose-dependent manner. Of them, the compound, 5,6,7,8-tetrahydro-7-(benzyl)-pyrido[4',3':4,5]thieno[2,3-d]pyrimidin-2,4-diamine, was found to significantly inhibit LCMV propagation in infected cells. Thereby, the present study demonstrated that a novel FRET biosensor incorporating Z assembly built on FRET and named Zabton, was a valuable screening tool to identify anti-arenavirus compounds in the context of inhibition of Z assembly.Key words: Arenavirus, Förster resonance energy transfer, anti-viral drugs, Z protein.
• STAT3β is a tumor suppressor in acute myeloid leukemia

  Petra Aigner, Tatsuaki Mizutani, Jaqueline Horvath, Thomas Eder, Stefan Heber, Karin Lind, Valentin Just, Herwig P Moll, Assa Yeroslaviz, Michael J M Fischer, Lukas Kenner, Balázs Győrffy, Heinz Sill, Florian Grebien, Richard Moriggl, Emilio Casanova, Dagmar Stoiber

  Blood Advances 3 13 1989 - 2002 2019年07月09日 [査読有り][通常論文]
   

  Signal transducer and activator of transcription 3 (STAT3) exists in 2 alternatively spliced isoforms, STAT3α and STAT3β. Although truncated STAT3β was originally postulated to act as a dominant-negative form of STAT3α, it has been shown to have various STAT3α-independent regulatory functions. Recently, STAT3β gained attention as a powerful antitumorigenic molecule in cancer. Deregulated STAT3 signaling is often found in acute myeloid leukemia (AML); however, the role of STAT3β in AML remains elusive. Therefore, we analyzed the STAT3β/α messenger RNA (mRNA) expression ratio in AML patients, where we observed that a higher STAT3β/α mRNA ratio correlated with a favorable prognosis and increased overall survival. To gain better understanding of the function of STAT3β in AML, we engineered a transgenic mouse allowing for balanced Stat3β expression. Transgenic Stat3β expression resulted in decelerated disease progression and extended survival in PTEN- and MLL-AF9-dependent AML mouse models. Our findings further suggest that the antitumorigenic function of STAT3β depends on the tumor-intrinsic regulation of a small set of significantly up- and downregulated genes, identified via RNA sequencing. In conclusion, we demonstrate that STAT3β plays an essential tumor-suppressive role in AML.
• Identification and Structure of an MHC Class I-Encoded Protein with the Potential to Present N-Myristoylated 4-mer Peptides to T Cells.

  Yukie Yamamoto, Daisuke Morita, Yoko Shima, Akihiro Midorikawa, Tatsuaki Mizutani, Juri Suzuki, Naoki Mori, Takashi Shiina, Hidetoshi Inoko, Yoshimasa Tanaka, Bunzo Mikami, Masahiko Sugita

  Journal of immunology (Baltimore, Md. : 1950) 202 12 3349 - 3358 2019年06月15日 [査読有り][通常論文]
   

  Similar to host proteins, N-myristoylation occurs for viral proteins to dictate their pathological function. However, this lipid-modifying reaction creates a novel class of "lipopeptide" Ags targeted by host CTLs. The primate MHC class I-encoded protein, Mamu-B*098, was previously shown to bind N-myristoylated 5-mer peptides. Nevertheless, T cells exist that recognize even shorter lipopeptides, and much remains to be elucidated concerning the molecular mechanisms of lipopeptide presentation. We, in this study, demonstrate that the MHC class I allele, Mamu-B*05104, binds the N-myristoylated 4-mer peptide (C14-Gly-Gly-Ala-Ile) derived from the viral Nef protein for its presentation to CTLs. A phylogenetic tree analysis indicates that these classical MHC class I alleles are not closely associated; however, the high-resolution x-ray crystallographic analyses indicate that both molecules share lipid-binding structures defined by the exceptionally large, hydrophobic B pocket to accommodate the acylated glycine (G1) as an anchor. The C-terminal isoleucine (I4) of C14-Gly-Gly-Ala-Ile anchors at the F pocket, which is distinct from that of Mamu-B*098 and is virtually identical to that of the peptide-presenting MHC class I molecule, HLA-B51. The two central amino acid residues (G2 and A3) are only exposed externally for recognition by T cells, and the methyl side chain on A3 constitutes a major T cell epitope, underscoring that the epitopic diversity is highly limited for lipopeptides as compared with that for MHC class I-presented long peptides. These structural features suggest that lipopeptide-presenting MHC class I alleles comprise a distinct MHC class I subset that mediates an alternative pathway for CTL activation.
• Neutrophils and the S100A9 protein critically regulate granuloma formation.

  Yuya Yoshioka, Tatsuaki Mizutani, Satoshi Mizuta, Ayumi Miyamoto, Satoru Murata, Toshiaki Ano, Hiroshi Ichise, Daisuke Morita, Hiroyuki Yamada, Yoshihiko Hoshino, Tatsuaki Tsuruyama, Masahiko Sugita

  Blood advances 1 3 184 - 192 2016年12月27日 [査読有り][通常論文]
   

  Macrophages have the potential to undergo cellular transformation into epithelioid cells, and their concentric accumulation in tissues results in the development of granulomas. Although epithelioid cells are an essential and dominant component of granulomas, other cell types have also been detected, which may contribute to the establishment of well-organized granulomas, as observed in human granulomatous diseases. We herein demonstrated that neutrophils may mediate these functions. By taking advantage of the guinea pig pulmonary granuloma model, we obtained a rat monoclonal antibody with unique reactivity to granuloma cells. This antibody, termed G213, reacted with clusters of neutrophils located in the central area of granulomas, and a biochemical analysis identified the G213-reactive antigen as S100A9, a calcium-binding protein of the S100 family, which was expressed abundantly in neutrophils. Consistent with the multifaceted functions attributed to S100A9, including its role in neutrophil extravasation and macrophage activation, the blockade of S100A9 functions with the specific inhibitor, tasquinimod, impaired the formation of organized granulomas with neutrophil cores. These results demonstrate the critical role of neutrophils and the S100A9 protein in granuloma formation. Because intragranuloma S100A9+ neutrophils were also detected in humans, these results indicate the potential of tasquinimod, a new anticancer drug candidate, for manipulating human granulomatous diseases.
• Crystal structure of the N-myristoylated lipopeptide-bound MHC class I complex.

  Daisuke Morita, Yukie Yamamoto, Tatsuaki Mizutani, Takeshi Ishikawa, Juri Suzuki, Tatsuhiko Igarashi, Naoki Mori, Takashi Shiina, Hidetoshi Inoko, Hiroaki Fujita, Kazuhiro Iwai, Yoshimasa Tanaka, Bunzo Mikami, Masahiko Sugita

  Nature communications 7 10356 - 10356 2016年01月13日 [査読有り][通常論文]
   

  The covalent conjugation of a 14-carbon saturated fatty acid (myristic acid) to the amino-terminal glycine residue is critical for some viral proteins to function. This protein lipidation modification, termed N-myristoylation, is targeted by host cytotoxic T lymphocytes (CTLs) that specifically recognize N-myristoylated short peptides; however, the molecular mechanisms underlying lipopeptide antigen (Ag) presentation remain elusive. Here we show that a primate major histocompatibility complex (MHC) class I-encoded protein is capable of binding N-myristoylated 5-mer peptides and presenting them to specific CTLs. A high-resolution X-ray crystallographic analysis of the MHC class I:lipopeptide complex reveals an Ag-binding groove that is elaborately constructed to bind N-myristoylated short peptides rather than prototypic 9-mer peptides. The identification of lipopeptide-specific, MHC class I-restricted CTLs indicates that the widely accepted concept of MHC class I-mediated presentation of long peptides to CTLs may need some modifications to incorporate a novel MHC class I function of lipopeptide Ag presentation.
• Conditional IFNAR1 ablation reveals distinct requirements of Type I IFN signaling for NK cell maturation and tumor surveillance.

  Tatsuaki Mizutani, Nina Neugebauer, Eva M Putz, Nadine Moritz, Olivia Simma, Eva Zebedin-Brandl, Dagmar Gotthardt, Wolfgang Warsch, Eva Eckelhart, Hans-Peter Kantner, Ulrich Kalinke, Stefan Lienenklaus, Siegfried Weiss, Birgit Strobl, Mathias Müller, Veronika Sexl, Dagmar Stoiber

  Oncoimmunology 1 7 1027 - 1037 2012年10月01日 [査読有り][通常論文]
   

  Mice with an impaired Type I interferon (IFN) signaling (IFNAR1- and IFNβ-deficient mice) display an increased susceptibility toward v-ABL-induced B-cell leukemia/lymphoma. The enhanced leukemogenesis in the absence of an intact Type I IFN signaling is caused by alterations within the tumor environment. Deletion of Ifnar1 in tumor cells (as obtained in Ifnar1(f/f) CD19-Cre mice) failed to impact on disease latency or type. In line with this observation, the initial transformation and proliferative capacity of tumor cells were unaltered irrespective of whether the cells expressed IFNAR1 or not. v-ABL-induced leukemogenesis is mainly subjected to natural killer (NK) cell-mediated tumor surveillance. Thus, we concentrated on NK cell functions in IFNAR1 deficient animals. Ifnar1(-/-) NK cells displayed maturation defects as well as an impaired cytolytic activity. When we deleted Ifnar1 selectively in mature NK cells (by crossing Ncr1-iCre mice to Ifnar1(f/f) animals), maturation was not altered. However, NK cells derived from Ifnar1(f/f) Ncr1-iCre mice showed a significant cytolytic defect in vitro against the hematopoietic cell lines YAC-1 and RMA-S, but not against the melanoma cell line B16F10. Interestingly, this defect was not related to an in vivo phenotype as v-ABL-induced leukemogenesis was unaltered in Ifnar1(f/f )Ncr1-iCre compared with Ifnar1(f/f) control mice. Moreover, the ability of Ifnar1(f/f) Ncr1-iCre NK cells to kill B16F10 melanoma cells was unaltered, both in vitro and in vivo. Our data reveal that despite the necessity for Type I IFN in NK cell maturation the expression of IFNAR1 on mature murine NK cells is not required for efficient tumor surveillance.
• ZAPS is a potent stimulator of signaling mediated by the RNA helicase RIG-I during antiviral responses.

  Sumio Hayakawa, Souichi Shiratori, Hiroaki Yamato, Takeshi Kameyama, Chihiro Kitatsuji, Fumi Kashigi, Showhey Goto, Shoichiro Kameoka, Daisuke Fujikura, Taisho Yamada, Tatsuaki Mizutani, Mika Kazumata, Maiko Sato, Junji Tanaka, Masahiro Asaka, Yusuke Ohba, Tadaaki Miyazaki, Masahiro Imamura, Akinori Takaoka

  Nature immunology 12 1 37 - 44 2011年01月 [査読有り][通常論文]
   

  The poly(ADP-ribose) polymerases (PARPs) participate in many biological and pathological processes. Here we report that the PARP-13 shorter isoform (ZAPS), rather than the full-length protein (ZAP), was selectively induced by 5'-triphosphate-modified RNA (3pRNA) and functioned as a potent stimulator of interferon responses in human cells mediated by the RNA helicase RIG-I. ZAPS associated with RIG-I to promote the oligomerization and ATPase activity of RIG-I, which led to robust activation of IRF3 and NF-κB transcription factors. Disruption of the gene encoding ZAPS resulted in impaired induction of interferon-α (IFN-α), IFN-β and other cytokines after viral infection. These results indicate that ZAPS is a key regulator of RIG-I signaling during the innate antiviral immune response, which suggests its possible use as a therapeutic target for viral control.
• A novel FRET-based biosensor for the measurement of BCR-ABL activity and its response to drugs in living cells.

  Tatsuaki Mizutani, Takeshi Kondo, Stephanie Darmanin, Masumi Tsuda, Shinya Tanaka, Minoru Tobiume, Masahiro Asaka, Yusuke Ohba

  Clinical cancer research : an official journal of the American Association for Cancer Research 16 15 3964 - 75 2010年08月01日 [査読有り][通常論文]
   

  PURPOSE: To develop a novel diagnostic method for the assessment of drug efficacy in chronic myeloid leukemia (CML) patients individually, we generated a biosensor that enables the evaluation of BCR-ABL kinase activity in living cells using the principle of fluorescence resonance energy transfer (FRET). EXPERIMENTAL DESIGN: To develop FRET-based biosensors, we used CrkL, the most characteristic substrate of BCR-ABL, and designed a protein in which CrkL is sandwiched between Venus, a variant of YFP, and enhanced cyan fluorescent protein, so that CrkL intramolecular binding of the SH2 domain to phosphorylated tyrosine (Y207) increases FRET efficiency. After evaluation of the properties of this biosensor by comparison with established methods including Western blotting and flow cytometry, BCR-ABL activity and its response to drugs were examined in CML patient cells. RESULTS: After optimization, we obtained a biosensor that possesses higher sensitivity than that of established techniques with respect to measuring BCR-ABL activity and its suppression by imatinib. Thanks to its high sensitivity, this biosensor accurately gauges BCR-ABL activity in relatively small cell numbers and can also detect <1% minor drug-resistant populations within heterogeneous ones. We also noticed that this method enabled us to predict future onset of drug resistance as well as to monitor the disease status during imatinib therapy, using patient cells. CONCLUSION: In consideration of its quick and practical nature, this method is potentially a promising tool for the prediction of both current and future therapeutic responses in individual CML patients, which will be surely beneficial for both patients and clinicians.
• Homeostatic erythropoiesis by the transcription factor IRF2 through attenuation of type I interferon signaling.

  Tatsuaki Mizutani, Kohichiro Tsuji, Yasuhiro Ebihara, Shinsuke Taki, Yusuke Ohba, Tadatsugu Taniguchi, Kenya Honda

  Experimental hematology 36 3 255 - 64 2008年03月 [査読有り][通常論文]
   

  OBJECTIVE: Erythrocyte production is tightly regulated by cytokines, particularly erythropoietin (EPO), which affects expansion and viability of erythroid lineage cells via induction of several factors, including Bcl2-like 1 (Bcl-XL). Because type I interferon (IFN) is known to inhibit erythropoiesis, we studied mice deficient in the gene for interferon regulatory factor 2 (IRF2), which functions as a negative regulator of type I IFN signaling, in the context of erythropoiesis regulation. MATERIALS AND METHODS: We performed hematologic analyses and detected normocytic anemia in Irf2-deficient mice. RESULTS: Assessment of the maturation of erythroid progenitors in Irf2-deficient bone marrow by flow cytometry revealed a decreased number of late erythroblasts accompanied by an increased number of early erythroid progenitors. Irf2-deficient mice manifested elevated serum EPO levels, decreased Bcl-XL expression levels and enhanced apoptosis of erythroblasts, which may account for the decreased number of late erythroblasts. We further assessed the role of IRF2 in the regulation of type I IFN signaling during erythropoiesis, and found that additional homozygous mutation of IFNAR1, a subunit of type I IFN receptor complex, led to rescue of the defect of erythropoiesis in Irf2-deficient mice. CONCLUSIONS: Impaired erythropoiesis in Irf2-deficient mice results from excessive type I IFN signaling, which inhibits Bcl-XL expression in erythroid lineage cells. Our present study provides a mechanistic understanding of the potential cross-talk between type I IFN and EPO signaling pathways during erythropoiesis and may offer therapeutic insights into anemia.
• IRF family transcription factors in type I interferon induction

  Hideyuki Yanai, Tatsuaki Mizutani, Takayuki Inuzuka, Kenya Honda, Akinori Takaoka, Tadatsugu Taniguchi

  International Congress Series 1285 104 - 113 2005年11月 [査読有り][招待有り]
   

  The type I interferon (IFN-α/β) gene family was identified about a quarter of century ago as the prototype of many cytokine gene families, and the gene induction mechanism for IFN-α/β was extensively studied in the context of host defense against viral infections. More recently, much attention has been focused on the induction and function of the IFN-α/β system regulated by Toll-like receptors (TLRs), which are critical for linking the innate and adaptive immunities. The understanding of mechanisms underlying IFN-α/β gene induction by TLRs is therefore an emerging theme, for which new insights have been gained over the past few years. We summarise recent progress on the role of interferon regulatory factors (IRFs) in the induction of IFN-α/β genes in normal cells and plasmacytoid dendritic cells (pDCs) that are specialized to produce IFN-α/β at very high levels upon stimulation by TLR9 and its subfamily members. © 2005 Elsevier B.V. All rights reserved.
• Spatiotemporal regulation of MyD88-IRF-7 signalling for robust type-I interferon induction.

  Kenya Honda, Yusuke Ohba, Hideyuki Yanai, Hideo Negishi, Tatsuaki Mizutani, Akinori Takaoka, Choji Taya, Tadatsugu Taniguchi

  Nature 434 7036 1035 - 40 2005年04月21日 [査読有り][通常論文]
   

  Robust type-I interferon (IFN-alpha/beta) induction in plasmacytoid dendritic cells, through the activation of Toll-like receptor 9 (TLR9), constitutes a critical aspect of immunity. It is absolutely dependent on the transcription factor IRF-7, which interacts with and is activated by the adaptor MyD88. How plasmacytoid dendritic cells, but not other cell types (such as conventional dendritic cells), are able to activate the MyD88-IRF-7-dependent IFN induction pathway remains unknown. Here we show that the spatiotemporal regulation of MyD88-IRF-7 signalling is critical for a high-level IFN induction in response to TLR9 activation. The IFN-inducing TLR9 ligand, A/D-type CpG oligodeoxynucleotide (CpG-A), is retained for long periods in the endosomal vesicles of plasmacytoid dendritic cells, together with the MyD88-IRF-7 complex. However, in conventional dendritic cells, CpG-A is rapidly transferred to lysosomal vesicles. We further show that conventional dendritic cells can also mount a robust IFN induction if CpG-A is manipulated for endosomal retention using a cationic lipid. This strategy also allows us to demonstrate endosomal activation of the IFN pathway by the otherwise inactive TLR9 ligand B/K-type oligodeoxynucleotide (CpG-B). Thus, our study offers insights into the regulation of TLR9 signalling in space, potentially suggesting a new avenue for therapeutic intervention.
• IRF-7 is the master regulator of type-I interferon-dependent immune responses.

  Kenya Honda, Hideyuki Yanai, Hideo Negishi, Masataka Asagiri, Mitsuharu Sato, Tatsuaki Mizutani, Naoya Shimada, Yusuke Ohba, Akinori Takaoka, Nobuaki Yoshida, Tadatsugu Taniguchi

  Nature 434 7034 772 - 7 2005年04月07日 [査読有り][通常論文]
   

  The type-I interferon (IFN-alpha/beta) response is critical to immunity against viruses and can be triggered in many cell types by cytosolic detection of viral infection, or in differentiated plasmacytoid dendritic cells by the Toll-like receptor 9 (TLR9) subfamily, which generates signals via the adaptor MyD88 to elicit robust IFN induction. Using mice deficient in the Irf7 gene (Irf7-/- mice), we show that the transcription factor IRF-7 is essential for the induction of IFN-alpha/beta genes via the virus-activated, MyD88-independent pathway and the TLR-activated, MyD88-dependent pathway. Viral induction of MyD88-independent IFN-alpha/beta genes is severely impaired in Irf7-/- fibroblasts. Consistently, Irf7-/- mice are more vulnerable than Myd88-/- mice to viral infection, and this correlates with a marked decrease in serum IFN levels, indicating the importance of the IRF-7-dependent induction of systemic IFN responses for innate antiviral immunity. Furthermore, robust induction of IFN production by activation of the TLR9 subfamily in plasmacytoid dendritic cells is entirely dependent on IRF-7, and this MyD88-IRF-7 pathway governs the induction of CD8+ T-cell responses. Thus, all elements of IFN responses, whether the systemic production of IFN in innate immunity or the local action of IFN from plasmacytoid dendritic cells in adaptive immunity, are under the control of IRF-7.
• Integral role of IRF-5 in the gene induction programme activated by Toll-like receptors.

  Akinori Takaoka, Hideyuki Yanai, Seiji Kondo, Gordon Duncan, Hideo Negishi, Tatsuaki Mizutani, Shin-Ichi Kano, Kenya Honda, Yusuke Ohba, Tak W Mak, Tadatsugu Taniguchi

  Nature 434 7030 243 - 9 2005年03月10日 [査読有り][通常論文]
   

  The activation of Toll-like receptors (TLRs) is central to innate and adaptive immunity. All TLRs use the adaptor MyD88 for signalling, but the mechanisms underlying the MyD88-mediated gene induction programme are as yet not fully understood. Here, we demonstrate that the transcription factor IRF-5 is generally involved downstream of the TLR-MyD88 signalling pathway for gene induction of proinflammatory cytokines, such as interleukin-6 (IL-6), IL-12 and tumour-necrosis factor-alpha. In haematopoietic cells from mice deficient in the Irf5 gene (Irf5-/- mice), the induction of these cytokines by various TLR ligands is severely impaired, whereas interferon-alpha induction is normal. We also provide evidence that IRF-5 interacts with and is activated by MyD88 and TRAF6, and that TLR activation results in the nuclear translocation of IRF-5 to activate cytokine gene transcription. Consistently, Irf5-/- mice show resistance to lethal shock induced by either unmethylated DNA or lipopolysaccharide, which correlates with a marked decrease in the serum levels of proinflammatory cytokines. Thus, our study identifies IRF-5 as a new, principal downstream regulator of the TLR-MyD88 signalling pathway and a potential target of therapeutic intervention to control harmful immune responses.
• Role of a transductional-transcriptional processor complex involving MyD88 and IRF-7 in Toll-like receptor signaling.

  Kenya Honda, Hideyuki Yanai, Tatsuaki Mizutani, Hideo Negishi, Naoya Shimada, Nobutaka Suzuki, Yusuke Ohba, Akinori Takaoka, Wen-Chen Yeh, Tadatsugu Taniguchi

  Proceedings of the National Academy of Sciences of the United States of America 101 43 15416 - 21 2004年10月26日 [査読有り][通常論文]
   

  Toll-like receptor (TLR) activation is central to immunity, wherein the activation of the TLR9 subfamily members TLR9 and TLR7 results in the robust induction of type I IFNs (IFN-alpha/beta) by means of the MyD88 adaptor protein. However, it remains unknown how the TLR signal "input" can be processed through MyD88 to "output" the induction of the IFN genes. Here, we demonstrate that the transcription factor IRF-7 interacts with MyD88 to form a complex in the cytoplasm. We provide evidence that this complex also involves IRAK4 and TRAF6 and provides the foundation for the TLR9-dependent activation of the IFN genes. The complex defined in this study represents an example of how the coupling of the signaling adaptor and effector kinase molecules together with the transcription factor regulate the processing of an extracellular signal to evoke its versatile downstream transcriptional events in a cell. Thus, we propose that this molecular complex may function as a cytoplasmic transductional-transcriptional processor.
• Crystal structure of the calcium pump with a bound ATP analogue.

  Chikashi Toyoshima, Tatsuaki Mizutani

  Nature 430 6999 529 - 35 2004年07月29日 [査読有り][通常論文]
   

  P-type ATPases are ATP-powered ion pumps that establish ion concentration gradients across cell and organelle membranes. Here, we describe the crystal structure of the Ca2+ pump of skeletal muscle sarcoplasmic reticulum, a representative member of the P-type ATPase superfamily, with an ATP analogue, a Mg2+ and two Ca2+ ions in the respective binding sites. In this state, the ATP analogue reorganizes the three cytoplasmic domains (A, N and P), which are widely separated without nucleotide, by directly bridging the N and P domains. The structure of the P-domain itself is altered by the binding of the ATP analogue and Mg2+. As a result, the A-domain is tilted so that one of the transmembrane helices moves to lock the cytoplasmic gate of the transmembrane Ca2+-binding sites. This appears to be the mechanism for occluding the bound Ca2+ ions, before releasing them into the lumen of the sarcoplasmic reticulum.
• Negative regulation of IFN-alpha/beta signaling by IFN regulatory factor 2 for homeostatic development of dendritic cells.

  Kenya Honda, Tatsuaki Mizutani, Tadatsugu Taniguchi

  Proceedings of the National Academy of Sciences of the United States of America 101 8 2416 - 21 2004年02月24日 [査読有り][通常論文]
   

  The development and cooperation of distinct subsets of antigen-presenting cells, particularly dendritic cells (DCs), may be critical for maintaining homeostatic immune responses. Recently, much attention has been focused on IFN-alpha/beta, the cytokines induced en masse by virus infection or the activation of Toll-like receptors, in the context of DC activation. Here, we show that mice deficient in IFN regulatory factor 2 exhibit selective loss of CD8alpha- DCs, the so-called myeloid DCs, which is accompanied by a notable increase in CD11c-CD11bhigh other myeloid lineage cells. Such deficiency is intrinsic to the bone marrow precursors, in which the abnormal induction of IFN-alpha/beta genes causes excessive IFN signaling. The critical function of IFN regulatory factor 2 in the negative regulation of IFN-alpha/beta signaling is underscored by the observation that the deficiency is rescued by introducing an additional null mutation for the IFN receptor complex. In view of accumulating evidence of the critical role of IFN-alpha/beta signaling in DC activation, our present study offers a unique example in that the magnitude of a cytokine signal should be properly balanced in a stage-specific manner during the differentiation and activation of DCs.
• Essential role of IRF-3 in lipopolysaccharide-induced interferon-beta gene expression and endotoxin shock.

  Shinya Sakaguchi, Hideo Negishi, Masataka Asagiri, Chigusa Nakajima, Tatsuaki Mizutani, Akinori Takaoka, Kenya Honda, Tadatsugu Taniguchi

  Biochemical and biophysical research communications 306 4 860 - 6 2003年07月11日 [査読有り][通常論文]
   

  Type I interferons (IFN-alpha/beta) affect many aspects of immune responses. Many pathogen-associated molecules, including bacterial lipopolysaccharide (LPS) and virus-associated double-stranded RNA, induce IFN gene expression through activation of distinct Toll-like receptors (TLRs). Although much has been studied about the activation of the transcription factor IRF-3 and induction of IFN-beta gene by the LPS-mediated TLR4 signaling, definitive evidence is missing about the actual role of IRF-3 in LPS responses in vitro and in vivo. Using IRF-3 deficient mice, we show here that IRF-3 is indeed essential for the LPS-mediated IFN-beta gene induction. Loss of IRF-3 also affects the expression of profile of other cytokine/chemokine genes. We also provide evidence that the LPS/TLR4 signaling activates IRF-7 to induce IFN-beta, if IRF-7 is induced by IFNs prior to LPS simulation. Finally, the IRF-3-deficient mice show resistance to LPS-induced endotoxin shock. These results place IRF-3 as a molecule central to LPS/TLR4 signaling.

MISC

• アレナウイルスZ蛋白の自己重合を検出するFRETバイオセンサーの開発と,それを利用した抗ウイルス薬スクリーニング法の確立

  水谷龍明, 大場雄介, 水田賢志, 浦田秀造 日本蛋白質科学会年会プログラム・要旨集 23rd (CD-ROM) 2023年
• 【グローバル時代の新興再興感染症への科学的アプローチ】デング・ジカ・SFTS・出血熱へのアプローチ ラッサウイルス・エボラウイルスに対する創薬研究

  泉澤 文子, 水谷 龍明, 浦田 秀造 生体の科学 72 (4) 326 -329 2021年08月 

  ＜文献概要＞ラッサ熱やエボラ出血熱(エボラウイルス病)は,一昔前までは限定された感染地域での封じ込めが可能だと考えられてきたことから,アフリカの風土病として位置づけられていた。しかしながら,2014-2016年の西アフリカ地域に端を発したエボラウイルスのアウトブレイクや,現在も流行がとどまることを知らないSARS-CoV-2によるCOVID-19にみられるように,これらの感染症対策は全世界的の緊迫した社会課題として顕在化した。筆者らは,ラッサウイルスやエボラウイルスといった高病原性ウイルスに対する新たな抗ウイルス薬の開発を目指し,ウイルスの特性,とりわけ細胞内複製機構や宿主免疫応答に着目した分子レベルの基礎解析を展開してきた。本稿では,ラッサウイルスのZタンパク質が有する多量体化機能に着目した新規の低分子化合物スクリーニング法と,その開発背景について概説する。
• S100A9は抗腫瘍型M1-TAMを誘導し、腫瘍成長を抑制する

  大和 勇輝, 水谷 龍明 日本癌学会総会記事 79回 OJ12 -2 2020年10月
• エボラウイルスVP40による粒子産生を標的とした新規化合物の同定

  浦田秀造, 浦田秀造, OMOTUYI Olaposi Idowu, 石川岳志, 水田賢志, 櫻井康晃, 櫻井康晃, 水谷龍明, 植田弘師, 田中義正, 安田二朗, 安田二朗, 安田二朗 日本薬学会年会要旨集(CD-ROM) 140th (Web) 27F -pm12 2020年
• 抗ラッサウイルス作用を有するリード阻害剤の創出

  水谷龍明, 浦田秀造, 水田賢志, 大場雄介 長崎大学熱帯医学研究拠点共同研究報告集 2018 2019年
• フィロウイルスVP40による粒子形成を阻害する新規化合物の同定

  浦田秀造, 石川岳志, 水田賢志, OLAPOSI Omotuyi, 水谷龍明, 植田弘師, 田中義正, 安田二朗, 安田二朗 日本ウイルス学会学術集会プログラム・予稿集(Web) 67th 2019年
• 結核肉芽腫形成を制御する好中球機能の解明

  水谷 龍明, 吉岡 祐弥, 大内 結貴, 森田 大輔, 杉田 昌彦 生命科学系学会合同年次大会 2017年度 [4LT24 -02(3P 2017年12月 [査読無し][通常論文]
  
• 免疫学 肉芽腫形成を制御するS100A9陽性好中球

  水谷 龍明, 杉田 昌彦 医学のあゆみ 263 (8) 671 -672 2017年11月 [査読無し][通常論文]
  
• 【非結核性抗酸菌症の今日的問題】 脂質免疫の新視点から見た非結核性抗酸菌感染症

  水谷 龍明, 杉田 昌彦 化学療法の領域 32 (8) 1477 -1483 2016年07月 [査読無し][通常論文]
   

  結核菌や非結核性抗酸菌,らい菌などの抗酸菌は脂質に富む堅牢な細胞壁を有している。この細胞壁の特質は菌の抗酸性を規定するだけでなく,菌の生存や病原性にも深く関与している。抗酸菌細胞壁脂質,とりわけその基本骨格を構成するミコール酸やミコール酸を含有した脂質群が宿主環境との接点において多様な免疫刺激活性を発揮し病態形成に寄与する。環境常在菌であるMAC(Mycobacterium avium complex)菌などの非結核性抗酸菌は宿主環境に適応してその脂質組成をダイナミックに変容させる。一方,宿主はこれを鋭敏に検知し,新たな免疫応答を誘起することが明らかとなりつつある。脂質変化とその免疫認識を基盤にした病原体:宿主間クロストークの研究は非結核性抗酸菌感染症の新たな診断法や予防法の確立へと結実しようとしている。(著者抄録)
• NK細胞の抗腫瘍活性におけるインターフェロンシグナルの役割

  水谷龍明, 水谷龍明, NEUGEBAUER Nina, PUTZ Eva M, SEXL Veronika, STOIBER Dagmar, STOIBER Dagmar 日本分子生物学会年会プログラム・要旨集(Web) 37th 2P-0804 (WEB ONLY) 2014年 [査読無し][通常論文]
  
• 抗ウイルス応答において活性化されるRIG-Iの強力な調節因子ZAPSの同定

  白鳥 聡一, 早川 清雄, 大和 弘明, 亀山 武志, 北辻 千展, 樫木 芙美, 後藤 翔平, 亀岡 章一郎, 藤倉 大輔, 山田 大翔, 水谷 龍明, 数馬田 美香, 佐藤 麻衣子, 田中 淳司, 浅香 正博, 大場 雄介, 宮崎 忠昭, 今村 雅寛, 高岡 晃教 北海道醫學雜誌 = Acta medica Hokkaidonensia 87 (4) 194 -194 2012年08月01日 [査読無し][通常論文]
  
• The role of STAT3 alpha in Pten-dependent hematopoietic malignancy

  Tatsuaki Mizutani, Emilio Casanova, Dagmar Stoiber CANCER RESEARCH 72 2012年04月 [査読無し][通常論文]
  
• 慢性骨髄白血病に対する分子標的治療薬の反応性・抵抗性判定試験(Seeing response and resistance to BCR-ABL inhibition in chronic myeloid leukemia)

  大場 雄介, 金安 顕子, 水谷 龍明, ダルマニン・ステファニー, 近藤 健, 津田 真寿美 日本癌学会総会記事 70回 242 -242 2011年09月 [査読無し][通常論文]
  
• 自然免疫系における核酸認識受容体を介したシグナルの新規調節因子と抗ウイルス作用

  亀山武志, 早川清雄, 白鳥聡一, 大和弘明, 北辻千展, 樫木芙美, 後藤翔平, 亀岡章一郎, 藤倉大輔, 水谷龍明, 数馬田美香, 佐藤麻衣子, 今村雅寛, 浅香正博, 大場雄介, 宮崎忠昭, 高岡晃教 日本ウイルス学会学術集会プログラム・抄録集 58th 220 2010年10月15日 [査読無し][通常論文]
  
• FRETバイオセンサーを用いたCML分子標的薬剤の薬効評価系の構築(A FRET-based biosensor for the evaluation of the efficacy of molecular targeted drugs for chronic myeloid leukemia)

  水谷 龍明, 近藤 健, ダルマニン・ステファニー, 津田 真寿美, 田中 伸哉, 浅香 正博, 大場 雄介 日本癌学会総会記事 68回 457 -457 2009年08月 [査読無し][通常論文]
  
• 慢性骨髄性白血病に対する分子標的治療薬の新たな薬効評価系の構築

  水谷龍明, 近藤健, STEPHANIE Darmanin, 津田真寿美, 川口秀明, 浅香正博, 大場雄介 日本病理学会会誌 98 (1) 278 2009年03月20日 [査読無し][通常論文]
  
• 慢性骨髄性白血病に対する分子標的治療薬の新たな薬効評価系の構築

  水谷龍明, 近藤健, DARMANIN Stephanie, 津田真寿美, 甲斐原拓真, 川口秀明, 浅香正博, 大場雄介 生化学 4P-1171 2008年 [査読無し][通常論文]
  
• 慢性骨髄性白血病に対する新たな診断技術の開発

  水谷龍明, 津田真寿美, 川口秀明, 大場雄介 生化学 4P-0935 2007年 [査読無し][通常論文]
  
• 樹状細胞群の分化と活性化の分子機構

  本田賢也, 柳井秀元, 水谷龍明, 根岸英雄, 大場雄介, 高岡晃教, 谷口維紹 日本分子生物学会年会プログラム・講演要旨集 27th 345 2004年11月25日 [査読無し][通常論文]
  
• 樹状細胞群におけるIRFファミリー転写因子の役割

  柳井秀元, 本田賢也, 朝霧政挙, 根岸英雄, 水谷龍明, 島田直也, 吉田進昭, 大場雄介, 高岡晃教 日本分子生物学会年会プログラム・講演要旨集 27th 593 2004年11月25日 [査読無し][通常論文]
  
• LPS応答における転写因子IRF‐3の機能解析

  坂口新也, 根岸英雄, 朝霧成挙, 中島千種, 水谷龍明, 高岡晃教, 本田賢也, 谷口維紹 日本免疫学会総会・学術集会記録 33 124 2003年11月05日 [査読無し][通常論文]
  

講演・口頭発表等

• 肉芽腫深部における好中球とマクロファージ相互作用  [通常講演]

  水谷龍明, 杉田昌彦

  第46回分子生物学会年会 2023年12月 ポスター発表
• Neutrophil S100A9-Cox2 axis dictates the formation of the M2 macrophage niche in granulomas  [通常講演]

  Tatsuaki Mizutani, Toshiaki Ano, Yuya Yoshioka, Satoshi Mizuta, Keiko Takemoto, Nagatoshi Fujiwara, Masahiko Sugita

  The 29th East Asia Joint Symposium 2023年10月 口頭発表（一般）
• 好中球S100A9による肉芽腫M2マクロファージの誘導機序,

  水谷龍明, 阿野敏明, 水田賢志, 鶴山竜昭, 藤原永年, 杉田昌彦

  第34回日本生体防御学会学術総会, 2023年09月
• STAT3β plays a tumor-suppressive role in acute myeloid leukemia  [通常講演]

  水谷龍明, Aigner P, Casanova E, Stoiber D

  第82回日本癌学会学術総会 2023年09月
• 肉芽腫形成を制御するS100A9  [通常講演]

  水谷 龍明, 吉岡佑弥, 杉田昌彦

  第29回日本生体防御学会学術総会 2018年06月 口頭発表（一般）
• 結核肉芽腫形成を制御する好中球機能の解明  [通常講演]

  水谷龍明

  第40回分子生物学会年会（2017年度生命科学系学会合同年次大会, ConBio2017） 2017年07月
• Evaluation of BCR-ABL activity in living CML cells by FRET-based monitors

  Tatsuaki Mizutani

  30th Annual Meeting of the Molecular Biology Society of Japan 2007年12月

所属学協会

• 日本分子生物学会   日本癌学会   日本細胞生物学会   

共同研究・競争的資金等の研究課題

• 癌助長性好中球におけるS100A9依存的転写制御メカニズムの解明

  日本学術振興会：科学研究費助成事業 基盤研究(C)

  研究期間 : 2022年04月 -2025年03月 

  代表者 : 水谷 龍明
• 好中球によるマクロファージ変容機序の解明～癌と結核の共通分子基盤を切り口にして～

  日本学術振興会：科学研究費助成事業 基盤研究(C)

  研究期間 : 2017年04月 -2020年03月 

  代表者 : 水谷 龍明, 杉田 昌彦

   

  研究代表者は、慢性炎症病態の成立基盤に関する研究を展開していたところ、結核持続感染で生じる肉芽腫においてS100A9 陽性の好中球サブセットが、マクロファージの持続的活性化を引き起こす鍵細胞である可能性を見出した。そこで本研究では、以下2点を目的として研究を実施している。 好中球又はS100A9に依存したマクロファージM2 誘導の分子機序解明 上記で得られた分子機序が、ヒト癌悪性化又は慢性炎症疾患において適用される可能性を検討し、好中球による疾患悪化の分子基盤の解明につなげる。 に関しては、モルモットを基盤にした上述の研究成果を、ヒト・マウスに発展させるために、①ヒト好中球を高純度に分離するラットモノクローナル抗体の作製、そして、マウス研究基盤の先駆けとして、②S100A9遺伝子欠損マウスの作製、③マウスBCG炎症モデルの樹立を行った。各項目の実施状況概要を下記に示す。①ヒト末梢血好中球を抗原とした抗体スクリーニングを実施することで、pan好中球抗体及びそのハイブリドーマ株の樹立に至った。②CRISPR/Cas9システムを活用し、タンパク発現欠損が予測されるin/del変異導入ライン（合計5ライン）のF0世代樹立に成功し、実際にS100A9タンパク質が欠失した3ラインの確立に成功した。③モルモットを利用した結核持続感染を反映する動物モデルとして、マウスBCG投与個体を検討中である。
• LPAプライミングとiPS細胞を用いた慢性疼痛病態神経回路要素の再構成と創薬

  日本学術振興会：科学研究費助成事業 基盤研究(A)

  研究期間 : 2014年04月 -2017年03月 

  代表者 : 植田 弘師, 松永 隼人, 永井 潤, 水田 賢志, 田中 義正, 水谷 龍明, 内田 仁司

   

  LPAシグナルは神経障害性疼痛、線維筋痛症モデルの形成と維持機構の共通鍵分子である事を明らかにし、創薬標的分子に対する阻害剤探索やin slico解析、最適化合成を行った。慢性疼痛は免疫系を含む複数のフィードフォワード機構により構成されることを見出したので、特異的薬剤処置やLPAプライミングした培養アストロサイト、iPS細胞、Ｔ細胞をin vivo疼痛機構に再構成する研究を実施した。その結果、ミクログリアLPA3受容体-サイトカインによる形成・維持機構、アストロサイトLPA1受容体-ケモカインによる維持機構が主な仕組みであることが明らかになった。
• プロサイモシンαによる癌幹細胞の創出・維持に関連した免疫抑制機構の解明

  日本学術振興会：科学研究費助成事業 若手研究(B)

  研究期間 : 2014年04月 -2016年03月 

  代表者 : 水谷 龍明

   

  癌は、何らかのメカニズムによって免疫系から許容され、表在化する。この癌の免疫抑制機構を明らかにするために、癌細胞から放出されるダメージ関連分子パターン（DAMPs）の一つであるプロサイモシンアルファ（PTMA）に着目し研究を推進した。はじめに、癌に対する免疫細胞の応答を適切に評価する新規の3次元細胞培養系を樹立した。次に、癌微小環境と結核病巣が類似している点に着目し、実際にがんと同様に結核病巣でマクロファージが免疫抑制型になっている事実を突き止めた。
• 骨髄幹細胞から免疫細胞への分化制御における分子基盤の解明

  日本学術振興会：科学研究費助成事業 特別研究員奨励費

  研究期間 : 2006年 -2007年 

  代表者 : 水谷 龍明

   

  転写因子IRF-2の遺伝子欠損マウスのin vivo解析から、同マウスの新たな表現型として慢性的貧血症状が新たに見出された。同遺伝子欠損マウスの貧血症状は正球性正色素性貧血に分類され、特にTer119high、CD71high細胞すなわち正染性赤芽球の分化ステージにおいて、高頻度にアポトーシス細胞が観測されることが明らかとなった。赤芽球の生存・増殖に必須とされているBcl-xlの発現量を同遺伝子欠損マウス骨髄細胞を用いてRT-PCRで解析したところ、野生型骨髄細胞と比較して有意に減少していることが見出された。転写因子IRF-2はI型インターフェロン(I型IFN)シグナルの負の調節因子であり、実際に同遺伝子欠損マウス骨髄細胞において過剰なI型IFNシグナル(I型IFN誘導遺伝子であるPKR、OASの高いレベルの発現)が検出された。過剰なI型IFNによる細胞増殖現象はよく知られていることから、赤芽球の分化・増殖抑制に対してもI型IFNが関与していることが推察された。そこで、I型IFN受容体欠損マウスとIRF-2遺伝子欠損マウスとの両欠損マウスを作成し、赤芽球異常を観察したところ、正常に回復された。以上のことより、I型IFNシグナル依存的に赤芽球分化抑制が起こっていることが個体レベルで明らかとなった。これはインターフェロン療法の際に、しばしば引き起こされる副作用の一つである貧血の原因解明につながる研究である。実際に、I型IFNシグナルによって、Bcl-xLの発現抑制がどのような分子メカニズムによるものかを解析すれば、効果的な貧血防止薬剤などの開発が可能であり、副作用の少ないインターフェロン療法の実施が実現する。抑制作用の分子基盤の解明に着手してきたが、未だ有用な手がかりが得られていない。I型IFNによる細胞分化抑制は、赤血球以外にも知られていることから他の抑制機構との比較検討からこの分子基盤解明につなげていきたいと考えている。