| Project/Area Number |
60065005
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| Research Category |
Grant-in-Aid for Specially Promoted Research
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| Allocation Type | Single-year Grants |
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| Research Institution | The University of Tokyo |
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Principal Investigator |
SAKAI Hikoichi Dept. Biophys. Biochem., Fac. Sci. Univ. Tokyo Professor, 理学部, 教授 (80011477)
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| Co-Investigator(Kenkyū-buntansha) |
ENDO Sachiko Dept. Biophys. Biochem., Fac. Sci. Univ. Tokyo Instructor, 理学部, 教務職員
MAEKAWA Shohei Dept. Biophys. Biochem., Fac. Sci. Univ. Tokyo Assistant Professor, 理学部, 助手 (40173695)
NISHIDA Eisuke Dept. Biophys. Biochem., Fac. Sci. Univ. Tokyo Assistant Professor, 理学部, 助手 (60143369)
MUROFUSHI Hiromu Dept. Biophys. Biochem., Fac. Sci. Univ. Tokyo Associate Professor, 理学部, 助教授 (70101128)
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| Project Period (FY) |
1985 – 1989
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| Project Status |
Completed (Fiscal Year 1989)
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| Budget Amount *help |
¥185,000,000 (Direct Cost: ¥185,000,000)
Fiscal Year 1989: ¥10,000,000 (Direct Cost: ¥10,000,000)
Fiscal Year 1988: ¥15,000,000 (Direct Cost: ¥15,000,000)
Fiscal Year 1987: ¥20,000,000 (Direct Cost: ¥20,000,000)
Fiscal Year 1986: ¥50,000,000 (Direct Cost: ¥50,000,000)
Fiscal Year 1985: ¥90,000,000 (Direct Cost: ¥90,000,000)
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| Keywords | Growth factor / Transduction of growth signal / Protein kinase / MAP-2 kinase / Centrosome / Microtubules / Mitotic apparatu / Cleavage signal / プロテインキナーゼ / 微小管 / 細胞分裂 / DNA合成 / 輸送モーター / 輸送モータ / 蛋白リン酸化 / 有系分裂 / 分裂収縮環 / 微小管形成中心 / 染色体運動 / 増殖因子受容体 / 細胞骨格 |
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| Research Abstract |
[Mechanism of signal transduction for call proliferatrion] : We demonstrated phosphorylation of high molecular weight microtubule-associated proteins (MAPS) as well as activation of a MAP-2 kinase after stimulation of cultured mammalian cells by growth factor or phorbol ester (promoter of carcinogenesis) and further identified a protein kinase which does not phosphorylate histone or casein but only MAP-2 and myelin basic-protein, proved to be a protein kinase newly identified. We further demonstrated that disassembly of microtubules produced by microtubule-disrupting drugs directly signals cell proliferation without stimulation by growth factor or pharbol ester. These results strongly suggest that MAP-2 kinase is involved in the cascade of phosphorylation in signal transduction for cell proliferation and demonstrate that microtubule cytoskeleton is directly relevant to the signal transduction, raising a now concept in the mechanism.
[Mechanism of the formation of the mitotic apparatus]
… More
: We identified the major protein component of the centrasons, 51-kD protein, and demonstrated its aster forming ability in the presence of some minor components of the contrasome and tubulin. The protein, which has an isoelectric point of 9.8 as basic protein, has an ability to bind guanine nucleotide, GTP and GDP, and proved to be a G protein. Furthermore, we demonstrated interconversion between GTP and GDP bound to the 51-kD protein, and the GTP-form protein is competent to be a signal protein for microtubule assembly. This provided a new standpoint in the mechanism of the formation of the mitotic apparatus, that is, the GTP<double arrow>GDP interconversion in the 51-kD protein sites governs the ability of the contrasome to initiate microtubules to build up the aster and the spindle. In fact, we demonstrated that isolated centrosomal fragments saturated with GTP (with the 51-kD protein saturated with GTP) can initiate astral microtubules much more efficiently than those saturated with GDP.
[Mechanism of transduction of cleavage signal] : We purified kinesin, which is most likely concerned with the trainduction of cleavage signal as a translocation motor, and characterized its enzymatic properties. We further isolated and purified a 260-kD protein which localizes underneath the cell membrane Just co-localized with actin bundles in the contractile ring. The 260-kD protein was shown to form curled thick actin bundles in vitro. Furthermore, an important finding is that a transmembrane glycoprotein labeled with WGA assembles as a precursor structure along the predicted contractile ring through the action of the cleavage signal which was shown to be dependent on microtubules, possibly astral microtubules. Less
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