細胞の増殖・分化のシグナル伝達機構

1996 年度 実績報告書

• 研究課題/領域番号: 06283221
• 研究機関: 大阪大学
• 研究代表者: 高井 義美 大阪大学, 医学部, 教授 (60093514)
• 研究分担者: 佐々木 卓也 大阪大学, 医学部, 助手 (40241278) ; 田中 一馬 大阪大学, 医学部, 助教授 (60188290)
• キーワード: 細胞骨格 / Rho / ERM / Rho GDI / BNI1 / CD44 / アクチン

研究概要

細胞が、がん化して浸潤能や転移能を獲得する過程において、細胞の形態や運動性、極性、接着性、分泌性等々の異常が重要な役割を果たしているが、これらの細胞機能は主としてアクチン系の細胞骨格により制御されている。一方、Rho低分子量G蛋白質が、私共を含めたいくつかのグループによって、アクチン細胞骨格の再編成を介して、上述した細胞機能を制御していることが明らかにされつつあり、Rhoを介するシグナル伝達経路の異常が、がん細胞の浸潤や転移において重要な役割を果たしている可能性が高い。本研究では、Rhoの活性化機構と作用機構に焦点をしぼって解析を行い、以下の成果を得た。私共は、アクチン繊維を細胞膜へAnchoringするERM(Ezrin,Radixin,Moesin)-CD44系が、Rhoの作用点として機能していることを明らかにしているが、このERMが、Rho-Rho GDI複合体に直接作用し、RhoをRho GDIから解離させて活性化反応を開始させる作用も有していることを明らかにした。一方、活性化されたRhoは、BNI1様標的蛋白質に作用し、アクチン結合蛋白質であるプロフィリンを介してアクチンの重合過程を制御すると共に、何らかの標的蛋白質を介して、ERMの細胞膜への移行過程、すなわちCD44との会合を制御することにより、アクチン細胞骨格の再編成を統合的に制御していることを明らかにした。以上の成果を得たことにより、本年度の研究は順調に進んだと考えている。

研究成果

• [文献書誌] Ohtsuka,T.: "Activation of brain B-Raf protein kinase by RaplB small GTP-binding protein" J.Biol.Chem.271. 1258-1261 (1996)
• [文献書誌] Orita,S.: "Doc2 enhances Ca^<2+>-dependent exocytosis from PC12 cells" J.Biol.Chem.271. 7257-7260 (1996)
• [文献書誌] Fujita,Y.: "phosphorylation of Munc-18/n-Secl/rbSecl by protein kinase C-Its implication in regulating the interaction of Munc-18/n-Secl/rbSecl with Syntaxin" J.Biol.Chem.271. 7265-7268 (1996)
• [文献書誌] Kuroda,S.: "Different effects of various phospholipids on Ki-Ras-,Ha-Ras,and RaplB-induced B-Raf activation" J.Biol.Chem.271. 14680-14683 (1996)
• [文献書誌] Simizu,K.: "SMAP,an Smg GDS-associating protein having Arm repeats and phosphorylated by Src tyrosine kinase" J.Biol.Chem.271. 27013-27017 (1996)
• [文献書誌] Kato,M.: "Physical and functional interaction of Rabphilin-3A with α-Actinin." J.Biol.Chem. 271. 31775-31778 (1996)
• [文献書誌] Hirano,H.: "ROM7/BEM4 encodes a novel protein that interacts with the Rholp small GTP-binding protein in Saccharomyces cerevisiae" Mol.Cell.Biol.16. 4396-4403 (1996)
• [文献書誌] Hirao,M.: "Regulation mechanism of ERM(Ezrin/Radixin/Moesin)protein/plasma membrane association - Possible involvement of phosphatidylinositol turnover and Rho-dependent signaling pathway" J.Cell.Biol.135. 37-51 (1996)
• [文献書誌] Masumoto,N.: "Involvement of Rabphilin-3A in cortical granule exocytosis in mouse eggs" J.Cell.Biol.135. 1741-1747 (1996)
• [文献書誌] Drgonova,J.: "Rholp,a yeast protein at the interface between cell polarization and morphogenesis" Science. 272. 277-279 (1996)
• [文献書誌] Ozaki,K.: "Romlp and Rom2p are GDP/GTP exchange proteins(GEPs) for the Rholp small GTP binding protein in Saccharomyces cerevisiae" EMBO J.15. 2196-2207 (1996)
• [文献書誌] Kohno,H.: "Bnilp implicated in cytoskeletal control is a putative target of Rholp small GTP binding protein in Saccharomyces cerevisiae" EMBO J.15. 6060-6068 (1996)
• [文献書誌] Matsuda,S.: "A membrane-associated GDP/GTP exchange protein specific for Rho small GTP-binding protein - Partial purification and characterization from rat brain" Oncogene. 12. 915-920 (1996)
• [文献書誌] Taniguchi,T.: "Cholecystokinin-B/gastrin receptors mediate rapid formation of actin stress fibers" Oncogene. 12. 1357-1360 (1996)
• [文献書誌] Komuro,R.: "Involvement of rabphilin-3A in Ca^<2+>-dependent exocytosis from PC12 cells" Biochem.Biophys.Res.Commun.219. 435-440 (1996)
• [文献書誌] Hotta,K.: "Interaction of the Rho family small G proteins with kinectin,an anchoring protein of kinesin motor" Biochem.Biophys.Res.Commun.225. 69-74 (1996)
• [文献書誌] Senbonmatsu,T.: "Interaction of Rabphilin3 with synaptic vesicles through multiple regions" Biochem.Biophys.Res.Commun.228. 567-572 (1996)
• [文献書誌] Oishi,H.: "Interaction of both the C2A and C2B domains of rabphilin3 with Ca^<2+> and pospholipid" Biochem.Biophys.Res.Commun.229. 498-503 (1996)
• [文献書誌] Hori,Y.: "Possible involvement of Rabll p24,a ras-like small GTP-binding protein,in intracellular vesicular transport of isolated pancreatic acini" Digestive Diseases and Sciences. 41. 133-138 (1996)
• [文献書誌] Regazzi,R.: "Expression,localization and functional role of small GTPases of the Rab3 family in insulinsecreting cells" J.Cell Sci.109. 2265-2273 (1996)
• [文献書誌] Komuro,R.: "Involvement of Rho and Rac small G proteins and Rho GDI in Ca^<2+>-dependent exocytosis from PC12 cells" Genes to Cells. 1. 943-951 (1996)
• [文献書誌] Takai,Y.: "Rab3A small GTP-binding protein in Ca^<2+>-dependent exocytosis" Genes to Cells. 1. 615-632 (1996)
• [文献書誌] Wada,M.: "Isolation and characterization of a GDP/GTP exchange protein specific for the Rab3 subfamily small G proteins" J.Biol.Chem.272. 3875-3878 (1997)
• [文献書誌] Fukui,K.: "Isolation and characterization of a GTPase activating protein specific for the Rab3 subfamily of small G proteins" J.Biol.Chem.272. 4655-4658 (1997)
• [文献書誌] Takeuchi,M.: "SAPAPs-A family of PSD-95/SAP90- associated proteins localized at postsynaptic density" J.Biol.Chem.(in press). (1997)
• [文献書誌] Imamura,H.: "Bnilp and Bnrlp - Downstream targets of the Rho family small G proteins which interact with profilin and regulate actin cytoskeleton in Saccharomyces cerevisiae" EMBO J.(in press). (1997)
• [文献書誌] Kotani,H.: "Rho regulates association of both the ERM family and vinculin with the plasma membrane in MDCK cells" Oncogene. (in press). (1997)
• [文献書誌] Naito,A.: "Molecular cloning of mouse Doc2α and distribution of its mRNA in adult mouse brain" Mol.Brain.Res.(in press). (1997)
• [文献書誌] Jin-no,Y.: "A novel function of the C-terminal lipid moieties of Rab3A small G protein implicated in Ca2+-dependent exocytosis -Inhibition of interaction with GTP and reduction of this inhibition by phospholipid" Genes to Cells. (in press). (1997)
• [文献書誌] Koch,G.A.: "Association of the Rho family small GPT-binding proteins with Rho GDP dissociation inhibitor(Rho GDI)in Saccharomyces cerevisiae" Oncogene. (in press). (1997)