研究者データベース

山口 良文(ヤマグチ ヨシフミ)
低温科学研究所 生物環境部門
教授

基本情報

所属

  • 低温科学研究所 生物環境部門

職名

  • 教授

学位

  • Ph.D(京都大学)

J-Global ID

プロフィール

  • 細胞社会における細胞死の制御とその意義について調べてきました。細胞の生き死にの境界を決めるものは何で、死にはどんな意義があるのか、哺乳類の初期発生、炎症応答、そして最近は哺乳類の冬眠に注目し研究を行なっています。哺乳類の冬眠は寒冷や飢餓といった厳しい環境変化に対する動物の適応機構ですが、個体の生き死にの狭間が見れる究極的な現象ともいえ、未開拓の地が残された魅惑的な研究分野です。

研究キーワード

  • 冬眠   細胞死   肝臓   脂質代謝   骨格筋   ビタミンE   マクロファージ   神経管閉鎖   発生生物学   カスパーゼ   アポトーシス   イメージング   時間生物学   包括脳ネットワーク   

研究分野

  • ライフサイエンス / 動物生理化学、生理学、行動学 / 冬眠の分子生物学・生理学
  • ライフサイエンス / 医化学 / 細胞死の生物学
  • ライフサイエンス / 発生生物学 / 哺乳類胚発生

職歴

  • 2018年01月 - 現在 北海道大学 低温科学研究所 教授
  • 2016年06月 - 2017年12月 東京大学 大学院薬学系研究科 准教授
  • 2007年 - 2016年06月 東京大学 大学院薬学系研究科 助教
  • 2006年 東京大学 薬学研究科(研究院) 助手

所属学協会

  • 日本筋学会   日本分子生物学会   日本 Cell Death学会   日本生化学会   日本生理学会   日本神経科学学会   日本発生生物学会   

研究活動情報

論文

  • Midori Awazu, Yoshifumi Yamaguchi, Michio Nagata, Masayuki Miura, Mariko Hida
    Biochemical and biophysical research communications 559 28 - 34 2021年06月25日 [査読有り]
     
    Inhibition of caspase-3 (Casp3) reduces ureteric branching in organ culture but the mechanism remains unclear. Since Casp3 has non-apoptotic functions, we examined whether Casp3 regulates ureteric branching by promoting cell migration, using a ureteric bud (UB) cell line and Casp3-deficient (Casp3-/-) mice. Also, we examined whether Casp3 plays a role in the reduced ureteric branching of metanephroi from nutrient restricted mothers, in which Casp3 activity is suppressed. A Casp3 inhibitor Ac-DNLD-CHO reduced FGF2-induced cord formation of UB cells in 3D culture. UB cell migration assessed by Boyden chamber and wound healing assays was inhibited by Ac-DNLD-CHO. Glomerular number was reduced by ≈ 30%, and ureteric tip number was lower in Casp3-/- mice compared with controls. Maternal nutrient restriction decreased ureteric tip number in controls but not in Casp3-/-. In conclusion, Casp3 regulates ureteric branching by promoting UB cell migration. Inhibited ureteric branching by maternal nutrient restriction may be mediated by Casp3.
  • Daisuke Anegawa, Yuki Sugiura, Yuta Matsuoka, Masamitsu Sone, Mototada Shichiri, Reo Otsuka, Noriko Ishida, Ken-Ichi Yamada, Makoto Suematsu, Masayuki Miura, Yoshifumi Yamaguchi
    Communications biology 4 1 796 - 796 2021年06月25日 [査読有り]
     
    Mammalian hibernators endure severe and prolonged hypothermia that is lethal to non-hibernators, including humans and mice. The mechanisms responsible for the cold resistance remain poorly understood. Here, we found that hepatocytes from a mammalian hibernator, the Syrian hamster, exhibited remarkable resistance to prolonged cold culture, whereas murine hepatocytes underwent cold-induced cell death that fulfills the hallmarks of ferroptosis such as necrotic morphology, lipid peroxidation and prevention by an iron chelator. Unexpectedly, hepatocytes from Syrian hamsters exerted resistance to cold- and drug-induced ferroptosis in a diet-dependent manner, with the aid of their superior ability to retain dietary α-tocopherol (αT), a vitamin E analog, in the liver and blood compared with those of mice. The liver phospholipid composition is less susceptible to peroxidation in Syrian hamsters than in mice. Altogether, the cold resistance of the hibernator's liver is established by the ability to utilize αT effectively to prevent lipid peroxidation and ferroptosis.
  • Ayako Yoshida, Daisuke Kawata, Naomi Shinotsuka, Mariko Yoshida, Yoshifumi Yamaguchi, Masayuki Miura
    Neuroscience research 2021年01月06日 [査読有り]
     
    A large number of cells undergo apoptosis via caspase activation during and after neural tube closure (NTC) in mammals. Apoptosis is executed by either intrinsic or extrinsic apoptotic pathways, and inhibition of each pathway causes developmental defects around NTC stages, which hampers the physiological roles of apoptosis and caspases after NTC. We generated transgenic mice in which a broad spectrum of caspases could be suppressed in a spatiotemporal manner by pan-caspase inhibitor protein p35 originating from baculovirus. Mice with nervous system-specific expression of p35 (Nestin-Cre (NCre);p35V mice) exhibited postnatal lethality within 1 month after birth. They were born at the expected Mendelian ratio, but demonstrated severe postnatal growth retardation and hydrocephalus. The flow of cerebrospinal fluid (CSF) between the third and fourth ventricles was disturbed, whereas neither stenosis nor abnormality in ciliary morphology was observed in the pathway of CSF flow. Hydrocephalus and growth retardation of NCre;p35V mice were not rescued by the deletion of RIPK3, an essential factor for necroptosis which occurs in the absence of caspase-8 activation during development. The CSF of NCre;p35V mice contained a larger amount of secreted proteins than that of the controls. These findings suggest that the establishment of proper CSF dynamics requires caspase activity during brain development after NTC.
  • Yudai Matsumoto, Yoshifumi Yamaguchi, Misato Hamachi, Keiko Nonomura, Yukiko Muramatsu, Hiroki Yoshida, Masayuki Miura
    Developmental biology 468 1-2 101 - 109 2020年12月01日 [査読有り]
     
    Apoptosis, a major form of programmed cell death, is massively observed in neural plate border and subsequently in the roof plate (RP). While deficiency of apoptosis often results in brain malformations including exencephaly and hydrocephalus, the impact of apoptosis on RP formation and maintenance remains unclear. Here we described that mouse embryos deficient in Apaf1, a gene crucial for the intrinsic apoptotic pathway, in C57BL/6 genetic background exhibited narrow and discontinuous expression of RP marker genes in the midline of the midbrain and the diencephalon. Instead, cells positive for the neuroectodermal gene SOX1 ectopically accumulated in the midline. A lineage-tracing experiment suggests that these ectopic SOX1-positive cells began to accumulate in the midline of apoptosis-deficient embryos after E9.5. These embryos further displayed malformation of the subcommissural organ, which has been discussed in the etiology of hydrocephalus. Thus, the apoptosis machinery prevents ectopic emergence of SOX1-positive cells in the midbrain and the diencephalon RP, and helps in maintaining the character of the RP in the diencephalon and midbrain, thereby ensuring proper brain development.
  • Koji Numasawa, Kenjiro Hanaoka, Naoko Saito, Yoshifumi Yamaguchi, Takayuki Ikeno, Honami Echizen, Masahiro Yasunaga, Toru Komatsu, Tasuku Ueno, Masayuki Miura, Tetsuo Nagano, Yasuteru Urano
    Angewandte Chemie (International ed. in English) 59 15 6015 - 6020 2020年04月06日 [査読有り][通常論文]
     
    Folate receptors (FRs) are membrane proteins involved in folic acid uptake, and the alpha isoform (FR-α) is overexpressed in ovarian and endometrial cancer cells. For fluorescence imaging of FRs in vivo, the near-infrared (NIR) region (650-900 nm), in which tissue penetration is high and autofluorescence is low, is optimal, but existing NIR fluorescent probes targeting FR-α show high non-specific tissue adsorption, and require prolonged washout to visualize tumors. We have designed and synthesized a new NIR fluorescent probe, FolateSiR-1, utilizing a Si-rhodamine fluorophore having a carboxy group at the benzene moiety, coupled to a folate ligand moiety through a negatively charged tripeptide linker. This probe exhibits very low background fluorescence and afforded a tumor-to-background ratio (TBR) of up to 83 in FR-expressing tumor-bearing mice within 30 min. Thus, FolateSiR-1 has the potential to contribute to the research in the field of biology and the clinical medicine.
  • Shin Murai, Yoshifumi Yamaguchi, Yoshitaka Shirasaki, Mai Yamagishi, Ryodai Shindo, Joanne M. Hildebrand, Ryosuke Miura, Osamu Nakabayashi, Mamoru Totsuka, Taichiro Tomida, Satomi Adachi-Akahane, Sotaro Uemura, John Silke, Hideo Yagita, Masayuki Miura, Hiroyasu Nakano
    Nature Communications 10 1 1923  2019年12月 [査読有り][通常論文]
  • Kohsuke Tsuchiya, Shinsuke Nakajima, Shoko Hosojima, Dinh Thi Nguyen, Tsuyoshi Hattori, Thuong Manh Le, Osamu Hori, Mamunur Rashid Mahib, Yoshifumi Yamaguchi, Masayuki Miura, Takeshi Kinoshita, Hiroko Kushiyama, Mayumi Sakurai, Toshihiko Shiroishi, Takashi Suda
    Nature Communications 10 1 2091  Springer Science and Business Media {LLC} 2019年12月 [査読有り][通常論文]
  • Hidenobu Miyazawa, Yukiko Muramatsu, Hatsune Makino, Yoshifumi Yamaguchi, Masayuki Miura
    Developmental dynamics : an official publication of the American Association of Anatomists 248 10 931 - 941 2019年10月 [査読有り][通常論文]
     
    BACKGROUND: The timing of developmental events is tightly regulated along a time axis for normal development. Although the RNA-binding protein Lin28a plays a crucial role in the regulation of developmental timing in Caenorhabditis elegans, how the timing of Lin28a expression affects the rate and/or duration of developmental events during mammalian development remains to be addressed. RESULTS: In this study, we discovered that the timing and the duration of Lin28a expression affect embryonic growth. During the neurulation stage of mouse development, endogenous Lin28a levels start to drop. When Lin28a expression was maintained transiently using the inducible tetracycline-regulated gene expression (Tet-ON) system [doxycycline (Dox)-inducible Lin28a transgenic (iLin28a Tg) mice] with Dox administration at E8.5 and E9.5, it resulted in neonatal lethality, increased body weight (organomegaly), and an increased number of caudal vertebrae at birth. On the other hand, Lin28a induction only at E8.5 caused neonatal lethality and organomegaly, but did not affect the caudal vertebra number. Of note, although Dox treatment before or after neurulation still caused neonatal lethality, it neither caused organomegaly nor the increased caudal vertebra number in iLin28a Tg neonates. CONCLUSIONS: Temporal regulation of Lin28a expression during neurulation affects developmental events such as cessation of axial elongation and embryonic growth in mice.
  • Martínez-Lagunas K, Yamaguchi Y, Becker C, Geisen C, DeRuiter MC, Miura M, Fleischmann BK, Hesse M
    Cell death and differentiation 2019年09月 [査読有り][通常論文]
  • Keisuke Hashimoto, Yoshifumi Yamaguchi, Yusuke Kishi, Yorifumi Kikko, Kanako Takasaki, Yurie Maeda, Yudai Matsumoto, Miho Oka, Masayuki Miura, Shinya Ohata, Toshiaki Katada, Kenji Kontani
    Genes to cells : devoted to molecular & cellular mechanisms 24 6 436 - 448 2019年06月 [査読有り][通常論文]
     
    Lysosomes are acidic organelles responsible for degrading both exogenous and endogenous materials. The small GTPase Arl8 localizes primarily to lysosomes and is involved in lysosomal function. In the present study, using Arl8b gene-trapped mutant (Arl8b-/- ) mice, we show that Arl8b is required for the development of dorsal structures of the neural tube, including the thalamus and hippocampus. In embryonic day (E) 10.5 Arl8b-/- embryos, Sox1 (a neuroepithelium marker) was ectopically expressed in the roof plate, whereas the expression of Gdf7 and Msx1 (roof plate markers) was reduced in the dorsal midline of the midbrain. Ectopic expression of Sox1 in Arl8b-/- embryos was detected also at E9.0 in the neural fold, which gives rise to the roof plate. In addition, the levels of Bmp receptor IA and phosphorylated Smad 1/5/8 (downstream of BMP signaling) were increased in the neural fold of E9.0 Arl8b-/- embryos. These results suggest that Arl8b is involved in the development of the neural fold and the subsequently formed roof plate, possibly via control of BMP signaling.
  • Polykratis A, Martens A, Eren RO, Shirasaki Y, Yamagishi M, Yamaguchi Y, Uemura S, Miura M, Holzmann B, Kollias G, Armaka M, van Loo G, Pasparakis M
    Nature cell biology 2019年05月 [査読有り][通常論文]
  • Hiroyasu Nakano, Shin Murai, Yoshifumi Yamaguchi, Yoshitaka Shirasaki, Osamu Nakabayashi, Soh Yamazaki
    Cell Stress 3 2 66 - 69 2019年02月11日 [査読有り][通常論文]
  • Yuichi Chayama, Lisa Ando, Yuya Sato, Shuji Shigenobu, Daisuke Anegawa, Takayuki Fujimoto, Hiroki Taii, Yutaka Tamura, Masayuki Miura, Yoshifumi Yamaguchi
    Frontiers in Physiology in press 1973  2019年01月 [査読有り][通常論文]
  • Shin Murai, Yoshifumi Yamaguchi, Yoshitaka Shirasaki, Mai Yamagishi, Ryodai Shindo, Joanne M. Hildebrand, Ryosuke Miura, Osamu Nakabayashi, Mamoru Totsuka, Taichiro Tomida, Satomi Adachi-Akahane, Sotaro Uemura, John Silke, Hideo Yagita, Masayuki Miura, Hiroyasu Nakano
    Nature Communications 9 1 4457  2018年12月 [査読有り][通常論文]
  • Hidenobu Miyazawa, Masamichi Yamamoto, Yoshifumi Yamaguchi, Masayuki Miura
    Genes to cells : devoted to molecular & cellular mechanisms 23 9 794 - 802 2018年09月 [査読有り][通常論文]
     
    Developing embryos rewire energy metabolism for developmental processes. However, little is known about how metabolic rewiring is coupled with development in a spatiotemporal manner. Here, we show that mammalian embryos display plasticity of glucose metabolism in response to the extracellular environment at the neural tube closure (NTC) stage, when the intrauterine environment changes upon placentation. To study how embryos modulate their metabolic state upon environmental change, we analyzed the steady-state level of ATP upon exposure to extrauterine environments using both an enzymatic assay and a genetically encoded ATP sensor. Upon environmental changes, NTC-stage embryos exhibited increased ATP content, whereas embryos before and after NTC did not. The increased ATP in the NTC-stage embryos seemed to depend on glycolysis. Intriguingly, an increase in mitochondrial membrane potential (ΔΨm) was also observed in the neural ectoderm (NE) and the neural plate border of the non-neural ectoderm (NNE) region. This implies that glycolysis can be coupled with the TCA cycle in the NE and the neural plate border depending on environmental context. Disrupting ΔΨm inhibited folding of the cranial neural plate. Thus, we propose that embryos tune metabolic plasticity to enable coupling of glucose metabolism with the extracellular environment at the NTC stage.
  • Naomi Shinotsuka, Yoshifumi Yamaguchi, Kenichi Nakazato, Yudai Matsumoto, Atsushi Mochizuki, Masayuki Miura
    BMC developmental biology 18 1 17 - 17 2018年07月31日 [査読有り][通常論文]
     
    BACKGROUND: Mammalian brain is formed through neural tube closure (NTC), wherein both ridges of opposing neural folds are fused in the midline and remodeled in the roof plate of the neural tube and overlying non-neural ectodermal layer. Apoptosis is widely observed from the beginning of NTC at the neural ridges and is crucial for the proper progression of NTC, but its role after the closure remains less clear. RESULTS: Here, we conducted live-imaging analysis of the mid-hindbrain neuropore (MHNP) closure and revealed unexpected collective behavior of cells surrounding the MHNP. The cells first gathered to the closing point and subsequently relocated as if they were released from the point. Inhibition of caspases or matrix metalloproteases with chemical inhibitors impaired the cell relocation. CONCLUSIONS: These lines of evidence suggest that apoptosis-mediated degradation of extracellular matrix might facilitate the final process of neuropore closure.
  • Miho Oka, Keisuke Hashimoto, Yoshifumi Yamaguchi, Shin-ichiro Saitoh, Yuki Sugiura, Yuji Motoi, Kurara Honda, Yorifumi Kikko, Shinya Ohata, Makoto Suematsu, Masayuki Miura, Kensuke Miyake, Toshiaki Katada, Kenji Kontani
    JOURNAL OF CELL SCIENCE 130 20 3568 - 3577 2017年10月 [査読有り][通常論文]
     
    The small GTPase Arl8b localizes primarily to lysosomes and is involved in lysosomal motility and fusion. Here, we show that Arl8b is required for lysosomal degradation of maternal proteins in the visceral yolk sac endoderm (VYSE), an apical cell layer of the visceral yolk sac, of mouse embryos. The VYSE actively takes up maternal materials from uterine fluid and degrades them in lysosomes to provide breakdown products to the embryo. Arl8b gene-trap mice (Arl8b(-/-)) displayed decreased early embryo body size. The Arl8b(-/-) VYSE exhibited defective endocytic trafficking to the lysosome and accumulation of maternal proteins such as albumin and immunoglobulin G in late endocytic organelles. Furthermore, Transthyretin-Cre; Arl8b(flox/flox) mice in which Arl8b was ablated specifically in the VYSE also showed decreased embryo body size, defects in trafficking to the lysosome and reduction of the free amino acid level in the embryos. Taken together, these results suggest that Arl8b mediates lysosomal degradation of maternal proteins in the VYSE, thereby contributing to mouse embryonic development.
  • Yoshifumi Yamaguchi, Hidenobu Miyazawa, Masayuki Miura
    CONGENITAL ANOMALIES 57 5 134 - 137 2017年09月 [査読有り][通常論文]
     
    Neural tube closure (NTC) is an embryonic process during formation of the mammalian central nervous system. Disruption of the dynamic, sequential events of NTC can cause neural tube defects (NTD) leading to spina bifida and anencephaly in the newborn. NTC is affected by inherent factors such as genetic mutation or if the mother is exposed to certain environmental factors such as intake of harmful chemicals, maternal infection, irradiation, malnutrition, and inadequate or excessive intake of specific nutrients. Although effects of these stress factors on NTC have been intensively studied, the metabolic state of a normally developing embryo remains unclear. State-of-the art mass spectrometry techniques have enabled detailed study of embryonic metabolite profiles and their distribution within tissues. This approach has demonstrated that glucose metabolism is altered during NTC stages involving chorioallantoic branching. An understanding of embryonic metabolic rewiring would help reveal the etiology of NTD caused by environmental factors.
  • Hidenobu Miyazawa, Yoshifumi Yamaguchi, Yuki Sugiura, Kurara Honda, Koki Kondo, Fumio Matsuda, Takehiro Yamamoto, Makoto Suematsu, Masayuki Miura
    DEVELOPMENT 144 1 63 - 73 2017年01月 [査読有り][通常論文]
     
    Adapting the energy metabolism state to changing bioenergetic demands is essential for mammalian development accompanying massive cell proliferation and cell differentiation. However, it remains unclear how developing embryos meet the changing bioenergetic demands during the chorioallantoic branching (CB) stage, when the maternal-fetal exchange of gases and nutrients is promoted. In this study, using metabolome analysis with mass- labeled glucose, we found that developing embryos redirected glucose carbon flow into the pentose phosphate pathway via suppression of the key glycolytic enzymes PFK-1 and aldolase during CB. Concomitantly, embryos exhibited an increase in lactate pool size and in the fractional contribution of glycolysis to lactate biosynthesis. Imaging mass spectrometry visualized lactate- rich tissues, such as the dorsal or posterior neural tube, somites and head mesenchyme. Furthermore, we found that the heterochronic gene Lin28a could act as a regulator of themetabolic changes observed during CB. Perturbation of glucose metabolism rewiring by suppressing Lin28a downregulation resulted in perinatal lethality. Thus, our work demonstrates that developing embryos rewire glucose metabolism following CB for normal development.
  • Tomohiro Doura, Mako Kamiya, Fumiaki Obata, Yoshifumi Yamaguchi, Takeshi Y. Hiyama, Takashi Matsuda, Akiyoshi Fukamizu, Masaharu Noda, Masayuki Miura, Yasuteru Urano
    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 55 33 9620 - 9624 2016年08月 [査読有り][通常論文]
     
    The LacZ gene, which encodes Escherichia coli beta-galactosidase, is widely used as a marker for cells with targeted gene expression or disruption. However, it has been difficult to detect lacZ-positive cells in living organisms or tissues at single-cell resolution, limiting the utility of existing lacZ reporters. Herein we present a newly developed fluorogenic beta-galactosidase substrate suitable for labeling live cells in culture, as well as in living tissues. This precisely functionalized fluorescent probe exhibited dramatic activation of fluorescence upon reaction with the enzyme, remained inside cells by anchoring itself to intracellular proteins, and provided single-cell resolution. Neurons labeled with this probe preserved spontaneous firing, which was enhanced by application of ligands of receptors expressed in the cells, suggesting that this probe would be applicable to investigate functions of targeted cells in living tissues and organisms.
  • Semba H, Takeda N, Isagawa T, Sugiura Y, Honda K, Wake M, Miyazawa H, Yamaguchi Y, Miura M, Jenkins DM, Choi H, Kim JW, Asagiri M, Cowburn AS, Abe H, Soma K, Koyama K, Katoh M, Sayama K, Goda N, Johnson RS, Manabe I, Nagai R, Komuro I
    Nature Communications 7 11635  2016年05月 [査読有り][通常論文]
     
    In severely hypoxic condition, HIF-1 alpha-mediated induction of Pdk1 was found to regulate glucose oxidation by preventing the entry of pyruvate into the tricarboxylic cycle. Monocyte-derived macrophages, however, encounter a gradual decrease in oxygen availability during its migration process in inflammatory areas. Here we show that HIF-1 alpha-PDK1-mediated metabolic changes occur in mild hypoxia, where mitochondrial cytochrome c oxidase activity is unimpaired, suggesting a mode of glycolytic reprogramming. In primary macrophages, PKM2, a glycolytic enzyme responsible for glycolytic ATP synthesis localizes in filopodia and lammelipodia, where ATP is rapidly consumed during actin remodelling processes. Remarkably, inhibition of glycolytic reprogramming with dichloroacetate significantly impairs macrophage migration in vitro and in vivo. Furthermore, inhibition of the macrophage HIF-1 alpha-PDK1 axis suppresses systemic inflammation, suggesting a potential therapeutic approach for regulating inflammatory processes. Our findings thus demonstrate that adaptive responses in glucose metabolism contribute to macrophage migratory activity.
  • Yuichi Chayama, Lisa Ando, Yutaka Tamura, Masayuki Miura, Yoshifumi Yamaguchi
    ROYAL SOCIETY OPEN SCIENCE 3 4 160002  2016年04月 [査読有り][通常論文]
     
    Hibernation is an adaptive strategy for surviving during periods with little or no food availability, by profoundly reducing the metabolic rate and the core body temperature (T-b). Obligate hibernators (e.g. bears, ground squirrels, etc.) hibernate every winter under the strict regulation of endogenous circannual rhythms, and they are assumed to undergo adaptive remodelling in autumn, the pre-hibernation period, prior to hibernation. However, little is known about the nature of pre-hibernation remodelling. Syrian hamsters (Mesocricetus auratus) are facultative hibernators that can hibernate irrespective of seasons when exposed to prolonged short photoperiod and cold ambient temperature (SD-Cold) conditions. Their T-b set point reduced by the first deep torpor (DT) and then increased gradually after repeated cycles of DT and periodic arousal (PA), and finally recovered to the level observed before the prolonged SD-Cold in the post-hibernation period. We also found that, before the initiation of hibernation, the body mass of animals decreased below a threshold, indicating that hibernation in this species depends on body condition. These observations suggest that Syrian hamsters undergo pre-hibernation remodelling and that T-b and body mass can be useful physiological markers to monitor the remodelling process during the pre-hibernation period.
  • Yoshifumi Yamaguchi, Masayuki Miura
    DEVELOPMENTAL CELL 32 4 478 - 490 2015年02月 [査読有り][通常論文]
     
    Programmed cell death (PCD) is an evolutionarily conserved contributor to nervous system development In the vertebrate peripheral nervous system, PCD is the basis of the neurotrophic theory, whereby cell death results from a surplus of neurons relative to target and competition for neurotrophic factors. In addition to stochastic cell death, PCD can be intrinsically determined by cell lineage or position and timing in both invertebrate and vertebrate central nervous systems. The underlying PCD molecular mechanisms include intrinsic transcription factor cascades and regulators of competence/susceptibility to cell death. Here, we provide a framework for understanding neural PCD from its regulation to its functions.
  • Yoshifumi Yamaguchi, Masayuki Miura
    APOPTOSIS AND DEVELOPMENT 114 159 - 184 2015年 [査読有り][通常論文]
     
    Programmed cell death (PCD) is a fundamental component of nervous system development. PCD serves as the mechanism for quantitative matching of the number of projecting neurons and their target cells through direct competition for neurotrophic factors in the vertebrate peripheral nervous system. In addition, PCD plays roles in regulating neural cell numbers, canceling developmental errors or noise, and tissue remodeling processes. These findings are mainly derived from genetic studies that prevent cells from dying by apoptosis, which is a major form of PCD and is executed by activation of evolutionarily conserved cysteine protease caspases. Recent studies suggest that caspase activation can be coordinated in time and space at multiple levels, which might underlie nonapoptotic roles of caspases in neural development in addition to apoptotic roles.
  • Yoshifumi Yamaguchi, Naomi Shinotsuka, Keiko Nonomura, Masayuki Miura
    New Principles in Developmental Processes 9784431546344 137 - 147 2014年11月01日 [査読有り][通常論文]
     
    Many cells die during development through the process called programmed cell death (PCD). Dysregulation of apoptosis, a major form of PCD during development, leads to cranial neural tube closure (NTC) defects such as exencephaly, but the underlying mechanism has remained unclear. Observing cells undergoing apoptosis in the normal developmental process will help elucidate their nature, characteristics, and interaction with surrounding tissues. Using a newly developed transgenic mouse that stably expressed a genetically encoded FRET-based fluorescent reporter for caspase activation, we performed simultaneous time-lapse imaging of apoptosis and morphogenesis in living embryos. This analysis, based on live imaging, indicated that inhibition of caspase activation interfered with and delayed the progression of NTC in the cranial region. The analysis also revealed existence of two types of apoptotic cells during NTC. Based on these results, we propose that cell removal by caspase-mediated apoptosis facilitates NTC and ensues the completion of NTC within a limited developmental time window.
  • Ting Liu, Yoshifumi Yamaguchi, Yoshitaka Shirasaki, Koichi Shikada, Mai Yamagishi, Katsuaki Hoshino, Tsuneyasu Kaisho, Kiwamu Takemoto, Toshihiko Suzuki, Erina Kuranaga, Osamu Ohara, Masayuki Miura
    CELL REPORTS 8 4 974 - 982 2014年08月 [査読有り][通常論文]
     
    Inflammasome-mediated caspase-1 activation is involved in cell death and the secretion of the proinflammatory cytokine interleukin-1 beta (IL-1 beta). Although the dynamics of caspase-1 activation, IL-1 beta secretion, and cell death have been examined with bulk assays in population-level studies, they remain poorly understood at the single-cell level. In this study, we conducted single-cell imaging using a genetic fluorescence resonance energy transfer sensor that detects caspase-1 activation. We determined that caspase-1 exhibits all-or-none (digital) activation at the single-cell level, with similar activation kinetics irrespective of the type of inflammasome or the intensity of the stimulus. Real-time concurrent detection of caspase-1 activation and IL-1 beta release demonstrated that dead macrophages containing activated caspase-1 release a local burst of IL-1 beta in a digital manner, which identified these macrophages as the main source of IL-1 beta within cell populations. Our results highlight the value of single-cell analysis in enhancing understanding of the inflammasome system and chronic inflammatory diseases.
  • Yoshifumi Yamaguchi, Erina Kuranaga, Yu-ichiro Nakajima, Akiko Koto, Kiwamu Takemoto, Masayuki Miura
    REGULATED CELL DEATH PT A: APOPTOTIC MECHANISMS 544 299 - 325 2014年 [査読有り][通常論文]
     
    Caspases, which constitute a family of cysteine proteases, are highly conserved in multicellular organisms and function as a central player in apoptosis. The detection of apoptosis is intrinsically difficult because dying cells are rapidly removed from tissues by phagocytosis. Thus, the development of a method for detecting caspase activation is critical for the in vivo study of apoptosis. In this chapter, we describe a genetically encoded fluorescent probe for live imaging of caspase activation.
  • Keiko Nonomura, Yoshifumi Yamaguchi, Misato Hamachi, Masato Koike, Yasuo Uchiyama, Kenichi Nakazato, Atsushi Mochizuki, Asako Sakaue-Sawano, Atsushi Miyawaki, Hiroki Yoshida, Keisuke Kuida, Masayuki Miura
    Developmental cell 27 6 621 - 34 2013年12月23日 [査読有り][通常論文]
     
    Apoptotic cells are observed in the early developing brain. Apoptosis deficiency is proposed to cause brain overgrowth, but here we show that brain malformations in apoptosis-deficient mutants are due to insufficient brain ventricle expansion as a result of uncompleted cranial neural tube closure. Apoptosis eliminates Fgf8-expressing cells in the anterior neural ridge (ANR), which acts as an organizing center of the forebrain by producing FGF8 morphogen. Deficiency of apoptosis leads to the accumulation of undead and nonproliferative cells in the ventral part of the ANR. The undead cells in apoptosis-deficient mutants express Fgf8 continuously, which perturbs gene expression in the ventral forebrain. Thus, apoptosis within a specific subdomain of the ANR is required for correct temporal elimination of an FGF8-producing region within a limited developmental time window, thereby ensuring proper forebrain development.
  • Yoshifumi Yamaguchi, Masayuki Miura
    Cellular and Molecular Life Sciences 70 17 3171 - 3186 2013年09月 [査読有り][通常論文]
     
    The development of the embryonic brain critically depends on successfully completing cranial neural tube closure (NTC). Failure to properly close the neural tube results in significant and potentially lethal neural tube defects (NTDs). We believe these malformations are caused by disruptions in normal developmental programs such as those involved in neural plate morphogenesis and patterning, tissue fusion, and coordinated cell behaviors. Cranial NTDs include anencephaly and craniorachischisis, both lethal human birth defects. Newly emerging methods for molecular and cellular analysis offer a deeper understanding of not only the developmental NTC program itself but also mechanical and kinetic aspects of closure that may contribute to cranial NTDs. Clarifying the underlying mechanisms involved in NTC and how they relate to the onset of specific NTDs in various experimental models may help us develop novel intervention strategies to prevent NTDs. © 2012 The Author(s).
  • Yoshifumi Yamaguchi, Naomi Shinotsuka, Keiko Nonomura, Kiwamu Takemoto, Keisuke Kuida, Hiroki Yosida, Masayuki Miura
    JOURNAL OF CELL BIOLOGY 195 6 1047 - 1060 2011年12月 [査読有り][通常論文]
     
    Many cells die during development, tissue homeostasis, and disease. Dysregulation of apoptosis leads to cranial neural tube closure (NTC) defects like exencephaly, although the mechanism is unclear. Observing cells undergoing apoptosis in a living context could help elucidate their origin, behavior, and influence on surrounding tissues, but few tools are available for this purpose, especially in mammals. In this paper, we used insulator sequences to generate a transgenic mouse that stably expressed a genetically encoded fluorescence resonance energy transfer (FRET)-based fluorescent reporter for caspase activation and performed simultaneous time-lapse imaging of apoptosis and morphogenesis in living embryos. Live FRET imaging with a fast-scanning confocal microscope revealed that cells containing activated caspases showed typical and nontypical apoptotic behavior in a region-specific manner during NTC. Inhibiting caspase activation perturbed and delayed the smooth progression of cranial NTC, which might increase the risk of exencephaly. Our results suggest that caspase-mediated cell removal facilitates NTC completion within a limited developmental window.
  • Ayako Yoshida, Yoshifumi Yamaguchi, Keiko Nonomura, Koichi Kawakami, Yoshiko Takahashi, Masayuki Miura
    GENES TO CELLS 15 5 501 - 512 2010年05月 [査読有り][通常論文]
     
    In utero electroporation is widely used to study neuronal development and function by introducing plasmid DNA into neural progenitors during embryogenesis. This is an effective and convenient method of introducing plasmid DNA into neural precursors and is suitable for manipulating gene expression in cells of the CNS. However, the applicability of this technique is comparatively limited to neuronal research, as the plasmid DNA introduced into neural progenitors during embryogenesis is diluted by cell proliferation and is not stably maintained in glial cells generated around and after birth. To overcome this limitation, we applied the Tol2 transposon system, which integrates a transgene into the genome of the host cell, to in utero electroporation. With this system, we confirmed that the transgene was effectively maintained in the progeny of embryonic neural precursors, astrocytes and oligodendrocytes. Using the glial promoters GFAP and S100 beta, targeted and stable expressions of transgenes in glia were obtained, which enabled the expression of different transgenes simultaneously in neurons and glia. Glia-targeted expression of the transgene that causes neuronal migration defect was achieved without the defect. Thus, use of the Tol2 transposon system in combination with in utero electroporation is a powerful method for studying glia-neuron interactions in vivo.
  • Yoshifumi Yamaguchi, Shigenobu Yonemura, Shinji Takada
    DEVELOPMENT 133 23 4737 - 4748 2006年12月 [査読有り][通常論文]
     
    Duct epithelial structure is an essential feature of many internal organs, including exocrine glands and the kidney. The ducts not only mediate fluid transfer but also help to maintain homeostasis. For instance, fluids and solutes are resorbed from or secreted into the primary fluid. owing through the lumen of the ducts in the exocrine glands and kidneys. The molecular mechanism underlying the functional maturation of these ducts remains largely unknown. Here, we show that a grainyhead-related transcription factor, CP2-like 1 (CP2L1), is required for the maturation of the ducts of the salivary gland and kidney. In the mouse, Cp2/1 is specifically expressed in the developing ducts of a number of exocrine glands, including the salivary gland, as well as in those of the kidney. In Cp2/1-deficient mice, the expression of genes directly involved in functional maturation of the ducts was specifically reduced in both the salivary gland and kidney, indicating that Cp2/1 is required for the differentiation of duct cells. Furthermore, the composition of saliva and urine was abnormal in these mice. These results indicate that Cp2/1 expression is required for normal duct development in both the salivary gland and kidney.
  • Y Yamaguchi, S Ogura, M Ishida, M Karasawa, S Takada
    DEVELOPMENTAL DYNAMICS 233 2 484 - 495 2005年06月 [査読有り][通常論文]
     
    In this study, we examined whether gene trap methodology, which would be available for systematic identification and functional analysis of genes, is effective for screening of Wnt-responsive genes during mouse development. We screened out two individual clones among 794 gene-trapped embryonic stem cell lines by their in vitro response to WNT-3A proteins. One gene was mainly expressed in the ductal epithelium of several developing organs, including the kidney and the salivary glands, and the other gene was expressed in neural crest cells and the telencephalic flexure. The spatial and temporal expression of these two genes coincided well with that of several Wnt genes. Furthermore, the expression of these two genes was significantly decreased in embryos deficient for Wnts or in cultures of embryonic tissues treated with a Wnt signal inhibitor. These results indicate that the gene trap is an effective method for systematic identification of Wnt-responsive genes during embryogenesis. (c) 2005 Wiley-Liss, Inc.

講演・口頭発表等

  • 冬眠する哺乳類に学ぶ、長期寒冷下での白色脂肪と骨格筋の可逆的リモデリング  [招待講演]
    山口良文
    第23回アディポサイエンス研究会 2018年08月 口頭発表(招待・特別)
  • 冬眠する哺乳類シリアンハムスターを用いた冬眠能の解析  [通常講演]
    山口良文
    モロシヌス研究会2018 2018年06月 口頭発表(一般)
  • Elucidating the roles and regulation of cell death in mammalian development and physiology  [通常講演]
    山口良文
    Australia-Japan Meeting on Cell Death 2018年05月 シンポジウム・ワークショップパネル(指名)
  • 冬眠する哺乳類シリアンハムスターの全身性代謝変化  [招待講演]
    山口良文
    生理研研究会「生命のエネルギー獲得戦略における多様性と共通原理の理解にむけて」 2018年04月 口頭発表(招待・特別)
  • Understanding seasonal body remodeling in mammalian hibernation  [招待講演]
    山口良文
    KEY-Forum "Stem Cell Traits and Developmental Systems" (Kumamoto, Japan) 2018年01月 口頭発表(招待・特別)
  • 哺乳類の冬眠を可能とする全身性代謝変化の分子基盤  [招待講演]
    山口良文
    ConBio2017(日本分子生物学会年会、神戸) 2017年12月 口頭発表(招待・特別)
  • カスパーゼ1活性の可視化から明らかになったインフラマソーム活性化様式  [招待講演]
    山口良文, 劉霞, 三浦正幸
    日本病態プロテアーゼ学会 2017年08月 口頭発表(招待・特別)
  • 冬眠可能な生体状態とは?シリアンハムスターを用いたアプローチ  [通常講演]
    山口良文
    第一回冬眠休眠研究会 2017年07月 口頭発表(一般)
  • Apoptosis is required for maintaining the character of the midbrain roof plate after the neural tube closure.  [通常講演]
    山口良文, 松本雄大, 濱地美里, 吉田三浦正幸
    第40回日本神経科学大会 2017年07月 ポスター発表
  • 哺乳類の代謝が全身性に変わる二つの局面〜「胚発生」と「冬眠」  [招待講演]
    山口良文
    がんと代謝研究会 2017年07月 公開講演,セミナー,チュートリアル,講習,講義等
  • 冬眠する哺乳類シリアンハムスターに学ぶ、冬眠可能な生体状態とは?  [招待講演]
    山口良文
    岡山実験動物研究会 2017年07月 口頭発表(招待・特別)
  • Rewiring of Embryonic Energy Metabolism During Mouse Chorioallantoic Branching  [招待講演]
    山口良文
    50th Annual Meeting of the Japanese Society of Developmental Biologists 2017年05月 口頭発表(招待・特別)
  • Investigation of mechanisms for skeletal muscle maintenance during hibernation season in a mammalian hibernator, Syrian golden hamster.  [通常講演]
    Yamaguchi, Y, Fujimoto, T, Ando, L, Chayama, Y, Anegawa, D, Taii, H, Tamura, Y, Shigenobu, S, Masayuki Miura, M
    94th Annual Meeting of Physiological Society of Japan., (Hamamatsu) 2017年03月 ポスター発表
  • 冬眠に先駆けて誘導される白色脂肪組織リモデリングの規定とその分子メカニズ ムの探索  [通常講演]
    茶山由一, 安藤理沙, 重信秀治, 佐藤祐哉, 姉川大輔, 藤本貴之, 泰井宙輝, 田村豊, 三浦正幸, 山口良文
    第12回環境生理プレコングレス 2017年03月 口頭発表(一般)
  • シリアンハムスターが冬眠期に示す骨格筋変化の解明  [通常講演]
    山口良文, 藤本貴之, 茶山由一, 安藤理沙, 姉川大輔, 泰井宙輝, 田村豊, 重信秀治, 三浦正幸
    第12回環境生理プレコングレス 2017年03月 口頭発表(一般)
  • 哺乳類胚発生と冬眠における代謝変化  [通常講演]
    山口良文, 宮沢英延, 茶山由一, 藤本貴之, 三浦正幸
    第4回 発生における代謝を考える会(京都) 2017年02月 口頭発表(一般)
  • 哺乳類の冬眠〜季節環境に応じた全身性の代謝抑制と体温制御  [招待講演]
    山口良文
    第1回Biothermology Workshop - 生命システムの熱科学 - 2016年12月 口頭発表(招待・特別)
  • 哺乳類の冬眠とは?~冬を乗り切るための代謝変化のメカニズム  [招待講演]
    山口良文
    東京大学発達保育実践政策学センター 第4回発達基礎科学セミナー 2016年11月 公開講演,セミナー,チュートリアル,講習,講義等
  • 死細胞からのシグナル放出のイメージング  [招待講演]
    山口良文
    千里ライフサイエンスセミナーK4 免疫・感染症シリーズ第6回「ワクチン、アジュバント開発研究の最前線」 2016年11月 口頭発表(招待・特別)
  • 冬眠する哺乳類シリアンハムスターに学ぶ、冬眠可能な生体状態とは?  [通常講演]
    山口良文
    第1回オモロイ生き物研究会 2016年10月 口頭発表(一般)
  • 冬眠する哺乳類シリアンハムスターに学ぶ、冬眠可能な生体状態とは?  [通常講演]
    山口良文
    広島大学大学院理学研究科第二回細胞生物学研究室セミナー 2016年09月 公開講演,セミナー,チュートリアル,講習,講義等
  • Investigation of mechanisms for the resistance to ischemia-reperfusion stress during hibernation period in Syrian hamsters  [通常講演]
    Anegawa, D, Chayama, Y, Ando, L, Shigenobu, S, Miura, M. Yamaguchi, Y
    15th International Hibernation Symposium (Las Vegas, USA) 2016年08月 口頭発表(一般)
  • Molecular remodeling of inguinal adipose tissue precedes hibernation period in Syrian golden hamster  [通常講演]
    Chayama, Y, Ando, L, Shigenobu, S, Tamura, Y, Miura, M, Yamaguchi, Y
    15th International Hibernation Symposium (Las Vegas, USA) 2016年08月 ポスター発表
  • Evidence for systemic remodeling prior to hibernation in the Syrian hamster (Mesocricetus auratus),  [通常講演]
    Yamaguchi, Y, Chayama, Y, Ando, L, Anegawa, D, Shigenobu, S, Fujimoto, T, Taii, H, Tamura, Y, Miura, M
    15th International Hibernation Symposium (Las Vegas, USA) 2016年08月 口頭発表(一般)
  • Pre-hibernation remodeling accompanies decreases in body temperature and body weight in a facultative mammalian hibernator, Syrian hamster  [通常講演]
    山口良文
    日本神経科学大会 2016年07月 ポスター発表
  • Elimination of the boundary cells by apoptosis in the dorsal midline of the midbrain after the neural tube closure  [通常講演]
    Yamaguchi, Y, Matsumoto, M, Hamachi, M, Nonomura, K, Shinotsuka, N, Miura, M
    Gordon Research Conference “Cell Death” (Girona, Spain) 2016年07月 ポスター発表
  • 死細胞のライブイメージング観察から視えるもの  [招待講演]
    山口良文
    第81回日本インターフェロン学会 2016年06月 口頭発表(招待・特別)
  • Evidence for systemic remodeling prior to hibernation in the Syrian hamster (Mesocricetus auratus),  [通常講演]
    Yamaguchi, Y, Chayama, Y, Ando, L, Shigenobu, S, Anegawa, D, Fujimoto, T, Tamura, Y, Miura, M
    NIBB conference: Evolution of Seasonal Timers (Okazaki, Japan) 2016年04月 口頭発表(一般)
  • Metabolic reorganization that supports growth of mouse embryos during the mid-gestation stage  [通常講演]
    山口良文
    CDB Symposium 2016, Size in Development: Growth, Shape and Allometry. 2016年03月 ポスター発表
  • 冬眠する哺乳類シリアンハムスターに学ぶ冬眠するための準備とは?  [招待講演]
    山口良文
    北海道大学遺伝子病制御研究所動物機能医科学研究室セミナー 2016年03月 公開講演,セミナー,チュートリアル,講習,講義等
  • 冬眠期の腎臓における虚血再灌流ストレス耐性機構の解明に向けて  [通常講演]
    姉川大輔, 茶山由一, 安藤理紗, 重信秀治, 三浦正幸, 山口良文
    第93回日本生理学会大会 2016年03月 ポスター発表
  • Evidence for systemic pre-hibernation remodeling in a mammalian hibernator, Syrian golden hamster  [通常講演]
    Yamaguchi, Y, Ando, L, Chayama, Y, Anegawa, D, Fujimoto, T, Shigenobu, S, Tamura, Y, Miura
    第93回日本生理学会大会 2016年03月 ポスター発表
  • 冬眠する哺乳類シリアンハムスターが前冬眠期に示す生体状態変化〜基礎体温と体重のセットポイント変化について  [通常講演]
    山口良文, 茶山由一, 安藤理沙, 姉川大輔, 重信秀治, 田村豊, 三浦正幸
    第11回環境生理プレコングレス(札幌) 2016年03月 口頭発表(一般)
  • 虚血再灌流ストレスによる組織障害に対しての冬眠期における耐性機構の解明  [通常講演]
    姉川大輔, 茶山由一, 安藤理紗, 三浦正幸, 山口良文
    新学術領域研究 酸素生物学&ダイイングコード 合同若手会議 2016年01月 ポスター発表
  • 哺乳類胎盤接続期に生じる胚のエネルギー代謝状態再編成の解明  [通常講演]
    宮沢英延, 山口良文, 杉浦悠毅, 山本正道, 本多久楽々, 山本鉱広, 末松誠, 三浦正幸
    新学術領域研究 酸素生物学&ダイイングコード合同若手会議 2016年01月 ポスター発表
  • What enables hibernation in mammals? ~ Identification of body remodeling for hibernation in the pre-hibernation period  [招待講演]
    山口良文
    第38回日本分子生物学会、ワークショップ「異種間比較が解き明かす生命システムの普遍性と多様性」 2015年12月 口頭発表(招待・特別)
  • 冬眠する哺乳類に学ぶ代謝変化  [招待講演]
    山口良文
    脳心血管抗加齢研究会2015 2015年11月 口頭発表(招待・特別)
  • Imaging Cell Death.  [通常講演]
    山口良文
    Japan Australia Meeting on Cell Death (WEHI, Melbourne, Australia) 2015年10月 口頭発表(一般)
  • アポトーシスとパイロトーシスのライブイメージング観察  [招待講演]
    山口良文
    第24回日本Cell Death学会学術集会 2015年07月 口頭発表(招待・特別)
  • 細胞死のライブイメージング  [招待講演]
    山口良文
    第15回蛋白質科学会年会ワークショップ「細胞死を起点とする生体制御ネットワーク」(徳島) 2015年06月 口頭発表(招待・特別)
  • 冬眠を可能とする分子機構同定に向けた網羅的遺伝子発現解析  [通常講演]
    山口良文, 茶山由一, 安藤理沙, 重信秀治, 田村豊, 三浦正幸
    第92回日本生理学会大会 2015年03月 ポスター発表
  • 異なる細胞死動態の単一細胞ライブイメージング  [通常講演]
    山口良文
    第87回日本生化学会 細胞死の多様性と生体応答〜細胞死の生物学の新たな側面〜、 2014年10月 口頭発表(一般)
  • 哺乳類の代謝が全身性に変わるとき〜胚発生と冬眠  [招待講演]
    山口良文
    第7回シンフォニー(東京) 2014年09月 口頭発表(招待・特別)
  • Modulation of early mammalian brain development through local apoptotic elimination of morphogen-producing cells. Cellular Dynamics in Early Mammalian Embyrogenesis  [招待講演]
    山口良文
    Japanese Society of Developmental Biology (Nagoya) 2014年05月 口頭発表(招待・特別)

その他活動・業績

共同研究・競争的資金等の研究課題

  • 冬眠モデル哺乳類シリアンハムスターの骨格筋可塑的リモデリング機構の解析
    日本学術振興会:科学研究費助成事業 基盤研究(B)
    研究期間 : 2019年04月 -2022年03月 
    代表者 : 山口 良文
  • 冬眠する哺乳類の自発的な低体温誘導機構の解析
    日本学術振興会:科学研究費助成事業 挑戦的研究(萌芽)
    研究期間 : 2018年06月 -2021年03月 
    代表者 : 山口 良文
     
    冬眠は、全身性の代謝抑制により低温・乾燥・飢餓といった極限環境下での長期生存を可能とする生存戦略である。冬眠する小型哺乳類であるジリスやシリアンハムスター(Mesocricetus auratus、以下ではハムと記載)は、冬眠期のあいだ、深冬眠と中途覚醒を繰り返す。深冬眠では、体温は外気温+1度まで低下し(外気温4度の場合、深部体温5-6度)、心拍数も1分間に10回程度まで低下する。深冬眠は数日から1週間近く経過したのち中途覚醒により中断される。深冬眠から中途覚醒への移行時には、体温は数時間で36度付近まで回復する。中途覚醒状態は半日程度継続し、再び体温が低下し深冬眠状態となる。ヒトやマウスなど多くの非冬眠哺乳類は長時間の低体温下では臓器機能を保持できず死に至ることを鑑みると、こうした冬眠自体が驚異的だが、その制御機構は未だ殆ど不明である。その要因として、冬眠研究のメインモデルであるリスやクマは、分子実体が全く不明の内因性の概年リズムに従い冬にしか冬眠しないため研究に時間を要する点、また野生由来のため遺伝的多様性や生息環境の違いなど個体差の影響が大きく結果の解釈が困難な点などがあげられる。一方、同じ冬眠動物であるハムは概年リズムに依存せず実験室での冬眠誘導が年間を通して可能、かつ遺伝的背景の比較的均一なアウトブレッドコロニーからの飼育個体の供給が可能なため、冬眠の分子機構検証モデルとして優れている。本研究では、体温が36度から低体温へと移行開始する深冬眠導入の際に発動するシグナルの同定を目指して研究を行なった。その結果、低体温移行時に発現が変動する遺伝子を複数同定することに成功した。
  • 日本学術振興会:科学研究費助成事業 基盤研究(B)
    研究期間 : 2016年04月 -2019年03月 
    代表者 : 山口 良文
     
    冬眠は、低温・乾燥・飢餓といった極限環境下を生き抜くために、全身性の代謝抑制により体温を低下させ低体温での長期生存を可能とする生存戦略である。これら冬眠動物の備える「冬眠耐性」は低体温で生存できないヒトなどの冬眠動物から見ると驚異的である。この冬眠耐性は通年発揮されるのではなく、前冬眠期から冬眠期にかけて誘導されることが示唆されるが、その分子実体の殆どは不明である。本研究では、冬眠可能な哺乳類シリアンハムスターにおける冬眠耐性発現機構の解明を、基礎体温および遺伝子発現のプロファイリングにより試みた。その結果、冬眠に先立つ基礎体温セットポイントの変更および白色脂肪組織リモデリングを明らかにした。
  • 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 : 2016年04月 -2019年03月 
    代表者 : 村井 晋, 中野 裕康, 山口 良文
     
    計画的ネクローシスは細胞外刺激に応答してリン酸化酵素RIPK3が活性化されMLKLと相互作用し活性化することでおこる。我々は計画的ネクローシスの誘導を可視化するため、MLKLのRIPK3結合領域を持つFRETバイオセンサー、SMARTを開発した。SMART発現細胞に計画的ネクローシスを誘導すると膜傷害に先行してFRETが起こった。他のタイプの細胞死ではFRETは見られないことから、SMARTが計画的ネクローシスの特異的なセンサーであることが証明された。またSMARTはRIPK3活性化によりFRETをおこすため、SMARTによってRIPK3活性を可視化することに世界で初めて成功した。
  • 日本学術振興会:科学研究費助成事業 新学術領域研究(研究領域提案型)
    研究期間 : 2015年11月 -2019年03月 
    代表者 : 田中 正人, 中野 裕康, 田中 稔, 須田 貴司, 安友 康二, 山崎 晶, 山口 良文, 袖岡 幹子
     
    日本とオーストラリアを中心とした細胞死関連研究者グループの緊密な国際連携体制を構築すること、および国際社会で活躍できる若手研究者の育成を行うことを目指して、以下の活動を行った。1) 日豪国際細胞死共同研究協議会(国内12名、海外7名)ならびに若手協議会(国内19名、海外22名)を開催した。 2) 研究者の国際派遣ならびに受け入れ等の人的交流を支援した(短期派遣1件 中期派遣1件 長期派遣2件 短期受入3件 長期受入2件 若手学会発表および打ち合わせ14件) 3) 国際共同研究の推進(計画研究班を中心とした18件、成果報告 8報)
  • 日本学術振興会:科学研究費助成事業 新学術領域研究(研究領域提案型)
    研究期間 : 2014年07月 -2019年03月 
    代表者 : 田中 正人, 中野 裕康, 田中 稔, 須田 貴司, 安友 康二, 山崎 晶, 山口 良文, 袖岡 幹子, 大村谷 昌樹, 荒川 聡子, 及川 彰
     
    本研究領域では、多様な細胞死の分子機構と、細胞死を起点として惹起される生体応答を解析し、それぞれの細胞死が持つ生理的・病理的意義を明らかにすることを目的とする。総括班はこの目的を達成するために、1) 班会議および総括班会議の開催 2)各種研究支援事業と共同研究プロジェクトの推進による領域内の連携強化 3)国内および国際シンポジウムの開催 4)若手研究者の育成支援 5) 領域ホームページの開設とニュースレターの発刊 6) 研究成果の一般公開を目的としたアウトリーチ活動の各種活動を行った。
  • 日本学術振興会:科学研究費助成事業 新学術領域研究(研究領域提案型)
    研究期間 : 2014年07月 -2019年03月 
    代表者 : 山口 良文, 荒川 聡子
     
    生体内における多様な細胞死動態の可視化とその意義の解明を目指し研究を行なった。パイロトーシス可視化プローブ、ネクロプトーシス可視化プローブの作出に成功した(Cell Rep 2014, Nature Commun 2018)。これと並行して、マウス発生過程における細胞死の意義と制御機構について解析し、神経管閉鎖過程での細胞死動態とその制御に新知見を得るとともに新規細胞死の役割を明らかにした(Dev Cell 2015, Development 2017, Genes Cells 2018, BMC Dev Biol 2018, Cell Death Differ 2017)。
  • 日本学術振興会:科学研究費助成事業 挑戦的萌芽研究
    研究期間 : 2016年04月 -2018年03月 
    代表者 : 山口 良文
     
    本研究は、未だその分子機構が不明な哺乳類の冬眠の謎の解明のため、近年進展著しいゲノム改変技術を冬眠動物シリアンハムスターに適用し冬眠研究に有用なシリアンハムスターを作出することを目指した。シリアンハムスターの受精卵が光に脆弱である点を克服するため、近年マウスにおいて開発された、輸卵管内での受精卵に対し遺伝子導入を行うGONAD法の適用を試みた。その結果、受精卵への核酸導入自体には成功した。しかし、遺伝子改変個体は得られなかった。その要因として、マウスの条件がシリアンハムスターには適さない点や飼育環境が挙げられる。冬眠研究に有用な遺伝子改変ハムスター作成のため、今後これらの点を改善したい。
  • マウス初期胚発生過程で細胞死が周辺細胞動態に与える影響の解明
    日本学術振興会:科学研究費助成事業 新学術領域研究(研究領域提案型)
    研究期間 : 2012年04月 -2014年03月 
    代表者 : 山口 良文
     
    本研究課題は、ほ乳類初期胚で生じる劇的な形態形成運動すなわち神経管閉鎖過程において、細胞死(アポトーシス)が周辺組織の組織動態にいかなる影響を与えるのか解明することを目的としている。具体的には、アポトーシスが多数見られかつその必要性が知られている、ほ乳類の頭部神経管閉鎖過程に着目し解析を行なった。 まず、アポトーシスが顕著に認められる、前脳前端のanterior neural ridge(ANR)と呼ばれる領域に着目した。アポトーシス欠損変異体のライブイメージング解析から、アポトーシス欠損により、この領域の運動性が損なわれ、組織融合がうまくいかないことが判明した 。アポトーシス欠損変異体では、本来これらの領域からアポトーシスにより除去されるFGF8発現細胞がANRに蓄積し、その結果FGF8蛋白質が前脳全域へと拡散分布してしまうこと、 さらにその結果、前脳領域の細胞分化パターンが異常になることが明らかとなった。このように、モルフォゲン産生細胞がアポトーシスにより発生の適切な時期までに除去されることが、脳の正常な形態形成およびパターニング必要であることが、本研究課題により初めて解明された(Nonomura et al., Dev Cell, 2013)。 一方、中脳-後脳領域でのアポトーシスについては、高解像度ライブイメージング系を構築し、神経管閉鎖運動および引き続いて生じる組織リモデリング過程の解析を行なった。その結果、アポトーシス欠損により神経管閉鎖後の上皮組織形態形成運動が障害されている様子が明らかとなった。その意義と機構の解明は今後の新しい研究課題といえる。
  • 日本学術振興会:科学研究費助成事業 挑戦的萌芽研究
    研究期間 : 2011年 -2012年 
    代表者 : 山口 良文
     
    進化的に保存されたタンパク質切断酵素であるカスパーゼが、睡眠をはじめとする脳恒常性維持過程にどのように関与するのか解明することを目指した。本研究では、細胞死実行に深く関わるカスパーゼ-3と、炎症応答に関与するカスパーゼ-1の活性化を検出・可視化できる新規プローブを用いて、既存の手法では検出されていない脳恒常性維持に関与する微弱なカスパーゼ活性化の検出を試みた。しかしながら、これらの新規プローブでも微弱なカスパーゼ活性化は検出されなかった。今後、検出法の改善等が必要と考えられる。

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主要な担当授業

  • 環境分子生物学特論Ⅰ
    開講年度 : 2019年
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : 微生物学、極限環境、分子生物学、生態学、分子昆虫学、哺乳類、発生生理化学、生化学 Microbiology,extremophiles,molecular biology,ecology,molecular Entomology, development and biochemistry in mammals
  • 分子生物学基礎論
    開講年度 : 2019年
    課程区分 : 修士課程
    開講学部 : 環境科学院
    キーワード : 分子生物学,転写,翻訳,微生物の群集構造解析,微生物の呼吸活性,電子顕微鏡観察,遺伝子操作,バイオフィルム形成,植物ストレス耐性,バイオセンサー,昆虫免疫系,昆虫体表脂質, 動物細胞 molecular biology, transcription, translation, bacterial culture, bacterial community structure analysis, bacterial respiration activity, electron microscopic observation, genetic manipulation, biofilm formation, stress tolerance of plants, biosensor, insect immune system, insect body surface lipids, animal cells
  • 一般教育演習(フレッシュマンセミナー)
    開講年度 : 2019年
    課程区分 : 学士課程
    開講学部 : 全学教育
    キーワード : 地球環境、環境適応、微生物、植物、昆虫、哺乳類、光合成、冬眠、生態、進化

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