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TANAKA Shuuitsu
Life Science DivisionProfessor
Regulatory Biology

Researcher information

■ Field Of Study
  • Life sciences, Genetics

Performance information

■ Paper
  • A mutation in DNA polymerase γ harbors a shortened lifespan and high sensitivity to mutagens in the filamentous fungus Neurospora crassa
    Ryouhei Yoshihara; Yuzuki Shimakura; Satoshi Kitamura; Katsuya Satoh; Manami Sato; Taketo Aono; Yu Akiyama; Shin Hatakeyama; Shuuitsu Tanaka
    GENETICS, Volume:229, Number:2, Nov. 2024, [Reviewed]
    Abstract

    Hyphal elongation is the vegetative growth of filamentous fungi, and many species continuously elongate their hyphal tips over long periods. The details of the mechanisms for maintaining continuous growth are not yet clear. A novel short lifespan mutant of N. crassa that ceases hyphal elongation early was screened and analyzed to better understand the mechanisms for maintaining hyphal elongation in filamentous fungi. The mutant strain also exhibited high sensitivity to mutagens such as hydroxyurea and ultraviolet radiation. Based on these observations, we named the novel mutant “mutagen sensitive and short lifespan 1 (ms1).” The mutation responsible for the short lifespan and mutagen sensitivity in the ms1 strain was identified in DNA polymerase γ (mip-1:NCU00276). This mutation changed the amino acid at position 814 in the polymerase domain from leucine to arginine (MIP-1 L814R). A dosage analysis by next-generation sequencing reads suggested that mitochondrial DNA (mtDNA) sequences are decreased nonuniformly throughout the genome of the ms1 strain. This observation was confirmed by quantitative PCR for 3 representative loci and restriction fragment length polymorphisms in purified mtDNA. Direct repeat-mediated deletions, which had been reported previously, were not detected in the mitochondrial genome by our whole-genome sequencing analysis. These results imply the presence of novel mechanisms to induce the nonuniform decrease in the mitochondrial genome by DNA polymerase γ mutation. Some potential reasons for the nonuniform distribution of the mitochondrial genome are discussed in relation to the molecular functions of DNA polymerase γ.
    Oxford University Press (OUP), Scientific journal
    DOI:https://doi.org/10.1093/genetics/iyae201
    DOI ID:10.1093/genetics/iyae201, eISSN:1943-2631
  • The msh1 gene is responsible for short life span mutant natural death and functions to maintain mitochondrial DNA integrity.               
    Mitsuyoshi Endo; Takato Yokoi; Suguru Hatazawa; Yuna Kojima; Shiena Takahama; Ryouhei Yoshihara; Shuuitsu Tanaka; Shin Hatakeyama
    Fungal genetics and biology : FG & B, Volume:144, First page:103465, Last page:103465, Nov. 2020, [Reviewed], [International magazine]
    Wild-type filamentous fungus Neurospora crassa continues to grow its hyphae for a very lengthy period of time (>2 years), whereas mutations at the natural death (nd) locus shorten life span (approximately 20 days). By positional cloning based on heat augmented mutagen sensitivity of the nd strain, we identified a nonsense mutation in the msh1 gene, an eukaryotic homolog of bacterial MutS, and this mutation resulted in encoding non-functional polypeptide. By tagging with GFP, subcellular localization of the MSH1 protein in the mitochondria was observed, and knock out of the msh1 gene caused severe growth deficiency accompanying mitochondrial DNA (mtDNA) aberrations such as large-scale mtDNA deletions and rearrangements as seen in the nd strain. These results suggested that MSH1 may maintain mtDNA integrity. Thus, loss of function compromises mtDNA, leading to the acceleration of cellular aging.
    English, Scientific journal
    DOI:https://doi.org/10.1016/j.fgb.2020.103465
    DOI ID:10.1016/j.fgb.2020.103465, PubMed ID:32949723
  • VASOACTIVE-INTESTINAL-PEPTIDE SUPPRESSES NEURONAL CELL-DEATH INDUCED BY NERVE GROWTH-FACTOR DEPRIVATION IN RAT SYMPATHETIC-GANGLION CELLS IN-VITRO               
    S TANAKA; T KOIKE
    NEUROPEPTIDES, Volume:26, Number:2, First page:103, Last page:111, Feb. 1994, [Reviewed]
    English, Scientific journal
    ISSN:0143-4179, Web of Science ID:WOS:A1994MW08200004
  • CAFFEINE PROMOTES SURVIVAL OF CULTURED SYMPATHETIC NEURONS DEPRIVED OF NERVE GROWTH-FACTOR THROUGH A CAMP-DEPENDENT MECHANISM               
    S TANAKA; T KOIKE
    BIOCHIMICA ET BIOPHYSICA ACTA, Volume:1175, Number:1, First page:114, Last page:122, Dec. 1992, [Reviewed]
    English, Scientific journal
    ISSN:0006-3002, Web of Science ID:WOS:A1992KG99300016
■ MISC
  • DNA鎖間架橋修復に関与するヌクレアーゼの遺伝学的解析               
    塚田耕太郎; 吉原亮平; 畠山晋; 田中秀逸
    Volume:92nd, 2020
    J-Global ID:202002243003078261
  • 複製ストレス応答におけるヒストンH3K4メチル化の重要性               
    柳澤健斗; 吉原亮平; 畠山晋; 田中秀逸
    Volume:92nd, 2020
    J-Global ID:202002259315982936
  • アカパンカビにおけるDNA損傷に応答したアポトーシス機構活性化の可視化に関する研究               
    田中秀逸
    Volume:第6号(平成19年度), 2008
  • アカパンカビにおけるDNA損傷に応答したアポトーシス機構活性化の可視化に関する研究               
    田中秀逸
    総合研究機構研究プロジェクト研究成果報告書, Volume:第6号(平成19年度), 2008
  • 高速分子進化による高機能バイオ分子の創出 : 相同組換え機能を使っての遺伝子ターゲッティング法               
    井上弘一; 田中秀逸; 畠山晋
    Volume:8, First page:24, Last page:26, 2007
  • アカパンカビにおけるDNA損傷応答に関する転写レベルのプロファイリング               
    田中秀逸
    Volume:第5号(18年度), First page:209, Last page:210, 2007
  • 高速分子進化による高機能バイオ分子の創出 : 相同組換え機能を使っての遺伝子ターゲッティング法               
    井上弘一; 田中秀逸; 畠山晋
    埼玉大学地域共同研究センター紀要, Volume:8, Number:8, First page:24, Last page:26, 2007
    DNA double strand breaks are mainly repaired by homologous recombination (HR) and nonhomologous end joining (NHEJ). In this article, we describe gene targeting efficiency in HR mutants and NHEJ mutants of the filamentous fungus Neurospora crassa. And we conclude that NHEJ-defective mutant is a most ideal host for gene targeting.
    Japanese
    ISSN:1347-4758, CiNii Articles ID:120001371294, CiNii Books ID:AA11808968
  • アカパンカビにおけるDNA損傷応答に関する転写レベルのプロファイリング               
    田中秀逸
    総合研究機構研究プロジェクト研究成果報告書, Volume:第5号(18年度), First page:209, Last page:210, 2007
  • 非相同組換え修復欠損細胞における標的遺伝子特異的な遺伝子破壊法の開発               
    田中秀逸
    Volume:第4号(17年度), 2006
  • 非相同組換え修復欠損細胞における標的遺伝子特異的な遺伝子破壊法の開発               
    田中秀逸
    総合研究機構研究プロジェクト研究成果報告書, Volume:第4号(17年度), 2006
  • Selective inflammatory stimulations enhance release of microglial response factor (MRF)-1 from cultured microglia               
    S Tanaka; T Koike
    GLIA, Volume:40, Number:3, First page:360, Last page:371, Dec. 2002
    English
    DOI:https://doi.org/10.1002/glia.10142
    DOI ID:10.1002/glia.10142, ISSN:0894-1491, eISSN:1098-1136, Web of Science ID:WOS:000179539700008
  • Activation of protein kinase C delays apoptosis of nerve growth factor-deprived rat sympathetic neurons through a Ca2+-influx dependent mechanism               
    S Tanaka; T Koike
    NEUROSCIENCE LETTERS, Volume:313, Number:1-2, First page:9, Last page:12, Nov. 2001
    English
    DOI:https://doi.org/10.1016/S0304-3940(01)02193-0
    DOI ID:10.1016/S0304-3940(01)02193-0, ISSN:0304-3940, Web of Science ID:WOS:000172059000003
  • Microglial response factor (MRF)-1: Constitutive expression in ramified microglia and upregulation upon neuronal death induced by ischemia or glutamate exposure               
    S Tanaka; H Kato; T Koike
    ZOOLOGICAL SCIENCE, Volume:17, Number:5, First page:571, Last page:578, Jul. 2000
    English
    DOI:https://doi.org/10.2108/zsj.17.571
    DOI ID:10.2108/zsj.17.571, ISSN:0289-0003, CiNii Articles ID:110003371170, PubMed ID:8940912, Web of Science ID:WOS:000088872800002
  • Upregulation of a new microglial gene, mrf-1, in response to programmed neuronal cell death and degeneration               
    S Tanaka; K Suzuki; M Watanabe; A Matsuda; S Tone; T Koike
    JOURNAL OF NEUROSCIENCE, Volume:18, Number:16, First page:6358, Last page:6369, Aug. 1998
    English
    ISSN:0270-6474, Web of Science ID:WOS:000075246500028
  • Veratridine delays apoptotic neuronal death induced by NGF deprivation through a Na+-dependent mechanism in cultured rat sympathetic neurons               
    S. Tanaka; T. Koike
    International Journal of Developmental Neuroscience, Volume:15, Number:1, First page:15, Last page:27, 31 Jul. 1997
    English
    DOI:https://doi.org/10.1016/S0736-5748(96)00082-2
    DOI ID:10.1016/S0736-5748(96)00082-2, ISSN:0736-5748, PubMed ID:9099612, SCOPUS ID:0030887258
  • Veratridine delays apoptotic neuronal death induced by NGF deprivation through a Na+ dependent mechanism in cultured rat sympathetic neurons.               
    TANAKA S; KOIKE T
    Volume:15, Number:1, First page:15, Last page:27, 1996
    DOI:https://doi.org/10.1016/S0736-5748(96)00082-2
    DOI ID:10.1016/S0736-5748(96)00082-2, ISSN:0736-5748, PubMed ID:9099612
  • UP-REGULATION OF L-TYPE CA2+ CHANNEL ASSOCIATED WITH THE DEVELOPMENT OF ELEVATED K+-MEDIATED SURVIVAL OF SUPERIOR CERVICAL-GANGLION CELLS IN-VITRO               
    S TANAKA; T KOIKE
    DEVELOPMENTAL BIOLOGY, Volume:168, Number:1, First page:166, Last page:178, Mar. 1995
    English
    DOI:https://doi.org/10.1006/dbio.1995.1069
    DOI ID:10.1006/dbio.1995.1069, ISSN:0012-1606, CiNii Articles ID:30018554932, PubMed ID:7883071, Web of Science ID:WOS:A1995QK99100014
  • PROGRAMMED NEURONAL CELL-DEATH IN PC12 CELLS PRIMED WITH NERVE GROWTH-FACTOR               
    T KOIKE; S TANAKA
    JOURNAL OF CELLULAR BIOCHEMISTRY, First page:150, Last page:150, Mar. 1993
    English, Summary international conference
    ISSN:0730-2312, Web of Science ID:WOS:A1993KV88000518
■ Research projects
  • High throughput gene-targeting with NHEJ deficient cells in plant               
    Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (C), 01 Apr. 2012 - 31 Mar. 2015
    TANAKA Shuuitsu, Saitama University
    Grant amount(Total):5590000, Direct funding:4300000, Indirect funding:1290000
    In the research, we will show the sure availability of a new system, which we had published in 2010, of gene targeting with NHEJ deficient cells in plant for analysis of gene function and plant bleeding.
    We had tried that a target gene tagged with GFP gene is expressed from LIG4 deficient A. thaliana, and gene targeting is performed in either KU80 deficient or KU70 knocked-down plants. Because of problems, may be, from either condition of calli culture or constructs for gene manipulation, neither their transformed plants nor results have not yet been obtained. But, we observed shoot formation from our cultured calli. These experiments will do continuously after addition of both some checks and modifications.
    Grant number:24570004
  • 非相同末端結合能破壊株を用いた高効率な遺伝子組換え作物作製技術の新規基盤開発               
    2009 - 2010
    Grant amount(Total):3200000, Direct funding:3200000
    Grant number:21658003
  • Mechanism of mtDNA deletion in short lived mutant of Neurospora.               
    Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (C), 2008 - 2010
    INOUE Hirokazu; TANAKA Shuuitsu; HATAKEYAMA Shin, Saitama University
    Grant amount(Total):4810000, Direct funding:3700000, Indirect funding:1110000
    The mus-10 mutant was isolated which showed highly sensitivity to alkylating agent methylmethane sulfonate (MMS). It had been forecasted that mus-10 gene belonged to the some DNA repair pathway, because of it sensitivity to mutagen. This mutant have other unique characteristics; unable to grow after several times sequential inoculation, or stop growing after 2 to 3 weeks culture. Furthermore, these phenotypes are accompanied the deletion of mitochondrial DNA and fragmented mitochondrial feature comparing to the normal (tubular) shape in wild type strain. The responsible gene of mus-10 was cloned by complementation of its MMS sensitivity. This gene encodes the F-box domain containing polypeptide, and deletion of F-box domain showed identical phenotype with mus-10 mutant. Since F-box protein is known as a counterpart of SCF (Skp-Cullin-F-box) comlex, which have a role for the degradation of some target protein via ubiquitination following degrading in The mus-10 mutant was isolated which showed highly sensitivity to alkylating agent methylmethane sulfonate (MMS). It had been forecasted that mus-10 gene belonged to the some DNA repair pathway, because of it sensitivity to mutagen. This mutant have other unique characteristics ; unable to grow after several times sequential inoculation, or stop growing after 2 to 3 weeks culture. Furthermore, these phenotypes are accompanied the deletion of mitochondrial DNA and fragmented mitochondrial feature comparing to the normal (tubular) shape in wild type strain. The responsible gene of mus-10 was cloned by complementation of its MMS sensitivity. This gene encodes the F-box domain containing polypeptide, and deletion of F-box domain showed identical phenotype with mus-10 mutant. Since F-box protein is known as a counterpart of SCF (Skp-Cullin-F-box) comlex, which have a role for the degradation of some target protein via ubiquitination following degrading in proteasome.
    To uncover the mus-10 gene function, we focused the feature of mitochondria. We examined whether 1) mitochondrial fusion is inhibited, or 2) mitochondrial fission is stimulated in mus-10 mutant. Double mutation of mus-10 and fis-1, which was essential for mitochondrial fission, showed quite resemble feature of mitochondria with wild type strain. And also this double mutant suppressed sensitivity to mutagen and short life span. These results suggested that MUS-10 protein prevent from the mutagen sensitivity and short life span according to maintain a mitochondrial feature. MUS-10 protein was considered to have a function of degradation of some target protein. So MUS-10 protein should be bound to that protein. Considering MUS-10 protein was correlated to maintenance of mitochondria feature, one candidate FZO-1 arose which had functions in the mitochondrial fusion. Using immunoprecipitation mthod, we could show that MUS-10 protein bound to FZO-1. Next, we tried to make fzo-1 knock out strain, but couldn't. The fzo-1 gene thought to be essential gene and fusion of mitochondria was important for maintenance of life span in Neurospora. Further, we forecasted that constitutive expression of FZO-1 protein in mus-10 mutant might show eviler phenotype than the mus-10 single mutant, because FZO-1, target of MUS-10, might be accumulated in that strain by escaping degradation. However, any evil phenotypes were not observed. Above these results, it was suggested that there were complex mechanism to maintain the mitochondrial feature.
    Grant number:20570001
  • ミトコンドリアゲノムの安定性維持機構               
    2008 - 2010
    Grant amount(Total):2000000, Direct funding:2000000
    Grant number:08F08756
  • Host for highly efficient gene targeting in filamentous fungi               
    Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (B), 2006 - 2007
    INOUE Hirokazu; TANAKA Syuuitu; HATAKEYAMA Shin; GOMI Katsuya; ABE Keietsu, Saitama University
    Grant amount(Total):9420000, Direct funding:8400000, Indirect funding:1020000
    To investigate gene function, most desirable method is gene targeting. However, gene targeting frequency is extremely low in many organisms. To raise the frequency, some trials have been carried out, but conclusive technique was not found.
    Double strand DNA breaks are repaired by two different recombination mechanisms: homologous recombination and nonhomologous end joining. From our study in Neurospora crassa, we speculated that homologous recombination frequency is increased if function of nonhomologous end joining is blocked. We disrupted ku70 and ku80 homolog genes of Neurospora and used them as a host in transformation experiments. In this study, high homologous integration of DNA was observed (Ninomiya, et. al. 2004).
    To develop more convenient host, we disrupted other Neurospora genes involving in nonhomologous end joining; Ligase IV and XRCC4 homolog genes. These mutants showed high targeting frequency even if homologous length of introduced DNA is short. We also tested targeting frequency in MRX-defective strains. MRX is complex of Mre11-Rad50-Xrs2 and functions in double strand breaks repair. Many transformants were from homologous integration, though transformation frequency was low.
    To know whether this system works in other organisms, Aspergillus oryzae was selected for test. Mutant of LigD ( human Lig4 homolog) was constructed in A. oryzae. Targeting experiments using ligD mutant as a host indicated high homologous integration.
    In many other fungi, similar experiments have been coducted by researchers all over the world and they confirmed high targeting efficiency by using ku mutants. as we presented.
    However, our trials in basidiomycetes did not reached to final step since there were unexpected problems in transformation, selection marker, so on. We will continue these experiments for construction of more convenient targeting system.
    Grant number:18370001
  • 神経突起変性により誘導されるカスケードとその神経変性疾患モデルにおける解析               
    2001 - 2001
    Grant amount(Total):5400000, Direct funding:5400000
    Competitive research funding, Grant number:13210002
  • 神経突起変性により誘発される細胞内カスケードの解明               
    2000 - 2000
    Competitive research funding, Grant number:12210023
  • BDNFは小脳外顆粒層由来顆粒細胞のアポトーシスを誘導するか?               
    1998 - 1999
    Grant amount(Total):2100000, Direct funding:2100000
    Grant number:10878145
  • Identification of novel microglial genes up-regulated during neuronal apoptosis               
    Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (B), 1997 - 1999
    KOIKE Tatsuro; TANAKA Shuuitsu; WATANABE Masahiko, HOKKAIDO UNIVERSITY
    Grant amount(Total):13400000, Direct funding:13400000
    To searach for genes up-regulated during neuronal cell death, we have employed cerebellar cell cultures, in which glial cells respond to degeneration and cell death of granule neurons that begins to occur at 4DIV. Differential hybridization was performed with subtracted cDNA probes and a cDNA library from 5DIV. One of the genes up-regulated during cell death is a novel gene, mrf-1, in microglia. Another gene is highly homologous to the mouse genes with hematopoietic cell origin which may be involved in microglial activation associated with enhanced functions of lysosomes
    Grant number:09480217
  • 神経細胞のアポトーシス抑制へのNF-KBカスケードの関与               
    1997 - 1998
    Grant amount(Total):2000000, Direct funding:2000000
    Grant number:09780715
  • 小胞体ストレスによるニューロン死制御               
    1997 - 1997
    Grant amount(Total):1500000, Direct funding:1500000
    Grant number:09280202
  • 神経細胞のアポトーシス初期過程で活性化する遺伝子の探索               
    1996 - 1996
    Grant amount(Total):1100000, Direct funding:1100000
    Grant number:08780693
  • 膜脱分極による遅延性遺伝子発現機構               
    1996 - 1996
    Grant amount(Total):2000000, Direct funding:2000000
    Grant number:08271201
  • 培養細胞モデル系によるニューロナルアポトーシスの分子機構               
    1996 - 1996
    Grant amount(Total):1500000, Direct funding:1500000
    Grant number:08256202
  • Studies on Regulatory Mechanisms of Developmental Neuronal Cell Death               
    Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for General Scientific Research (B), 1994 - 1995
    KOIKE Tatsuro, HOKKAIDO UNIVERSITY
    Grant amount(Total):5700000, Direct funding:5700000
    We have shown previously that neuronal survival under depolarizing conditions correlates well with sustained levels of cytoplasmic free calcium ([Ca^<2+>]_i) in rat superior cervical ganglion (SCG) cells and cerebellar granule neurons. Moreover, developmental acquisition of trophic factor-independent survival is coincident with a gradual elevation of[Ca^<2+>]_i in SCG and sensory neurons. In contrast, when basal levels of[Ca^<2+>]_i in these neurons were decreased by treatment with an excessive dose of the Ca^<2+> chelator BAPATAAM,these neurons died following fragmentation of chromatin as visualized by fluorescent staining with bis-benzamide, a hallmark of apoptosis. Indeed, our Ca^<2+> set-point hypothesis predicts that a decrease in the level of cytoplasmic Ca^<2+> occurs during neuronal death following trophic factor withdrawal. In support of this, when SCG neurons were treated with 10-20 muM BAPTA-AM thus chelating the level of intracellular Ca^<2+>, they became resistant to NGF deprivation. Fura-2 measurements of[Ca^<2+>]_i also indicated a decrease in basal Ca^<2+> levels. Since there is evidence suggesting that NGF facilitates Ca^<2+>-dependent processes in these neurons, NGF deprivation causes a disruption of Ca^<2+> homeostasis in these neurons thus leading to the activation of neuronal apoptosis cascades.
    Grant number:06454686
  • 過剰なNa^+流入による神経細死の機構               
    1994 - 1994
    Grant amount(Total):2200000, Direct funding:2200000
    Grant number:06272225
  • 神経栄養因子欠乏による神経細胞死の機序               
    1992 - 1992
    Grant amount(Total):2200000, Direct funding:2200000
    Grant number:04258216
  • Neuronal Cell Degeneration Cascade               
    Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for General Scientific Research (C), 1991 - 1992
    KOEKI Tatsuro; TANAKA Shuuitsu, SAGA MEDICAL SCHOOL
    Grant amount(Total):1700000, Direct funding:1700000
    PC12 cells undergo degeneration after nerve growth factor (NGF) withdrawal only when they have been treated with NGF Actinomycin D or cordycepin blocked the release of lactate dehyrogenase (LDH) activity up to 85-90%; the residual release was due to neurite degeneration. Thus, NGF deprivation-induced cell death of PC12 cells occurs in a transcription-dependent manner, while serum deprivation-induced PC12 cell death has been reported to be a transcription-independent process. The cell death was completely prevented by chronic depolarization with high potassium (>35mM), CPT-cAMP(>0.1mM), acidic and basic FGF(10ng/ml). Upon NGF deprivation, rapid dephosphorylation of major tyrosine-phosphorylated proteins, p120, p80, p70 as well as p140 trk occurred followed by gradual down-regulation of kinase activities (Ser/Thr) which appears to require RNA and protein synthesis. These results suggest that a dephosphorylation cascade initiated by trophic factor deprivation is highly reulated, and may constitute a part of programmed neuronal death cascade(s).
    Grant number:03833026
  • 神経栄養因子欠乏による神経細胞死の機序               
    1991 - 1991
    Grant amount(Total):2000000, Direct funding:2000000
    Grant number:03263217
  • 栄養因子欠如による神経細胞死の分子生物学的研究               
    1990 - 1990
    Grant amount(Total):1400000, Direct funding:1400000
    Grant number:02807012
  • 交感神経節細胞の神経成長因子依存性と細胞内カルシウム               
    1989 - 1989
    Grant amount(Total):1700000, Direct funding:1700000
    Grant number:01641533
  • Regulatory Mechanisms of Cellular Responses to Nerve Growth Factor(NGF) --Studies on the Interaction between NGF and NGF Receptors--               
    Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for General Scientific Research (C), 1987 - 1988
    TANAKA Shuitsu; TAKASHIMA Akihiko; KOIKE Tatsuro, Saga Medical School
    Grant amount(Total):1900000, Direct funding:1900000
    1. Response to NGF by PC12 cells is regulated by modulation of NGF receptors. Fractions of the binding and internalization of ^<125>I-NGF by the cells increased with an increase in extracellular potassium concentration. This high K^+ effect was also induced by treatment of the cells with veratridine. Neurite outgrowth of the cells in the presence of low concentrations of NGF was potentiated in high K^+ medium. The fractions of ^<125>I-NGF binding and internalization by the cells were also influenced by treatent of the cells with catecholamines.
    2. A regulatory mechanism of dopamine release in PC12 cells. Pre-treatment of the cells with phorbol ester(TPA) resulted in enhanced dopamine release, which could be further stimulated by high K^+. This enhanced dopamine release was associated with concomitant reduction of the high K^+-induced increase in intracellular Ca^<2+> concentration. Moreover, in TPA-treated cells, the high K^+-evoked dopamine release was completely abolished by the presence of nicardipine, Cd^<2+>, or Co^<2+>, but only partially inhibited by the presence of verapamil. These findings suggest possible involvement of protein kinase C in regulating the efficiency of high K^+-evoked dopamine release through the modification of nicardipine-sensitive Ca^<2+> channels.
    3. Enhancement of the NGF action by intracellular application of GTP analougues. Pre-treatment of PC12 cells with NGF induced an increase in the fraction of ^<35>S-GTP S bound to the cell membranes. The fractions of the cell-surface binding of ^<125>I-NGF were measured after introduction of some nucleotides into the cytoplasm by electric pulses. Introduction of GTP s or GTP into the cytoplasm caused an increase in the fraction of ^<125>I-NGF binding. Moreover, the number of cells which grew neurite increased when GTP s or GTP was introduced into theic cytoplasm before a treatment of the cell with NGF for 1-2 hours. These results indicate that GTP plays a role in the process of the binding of NGF to NGF receptors.
    Grant number:62540552
  • アカパンカビの遺伝学的研究-DNA損傷後のDNA修復と細胞死との選択制御-               
    Competitive research funding
  • -               
    Competitive research funding
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