权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Studies on the mechanism of cell division in animal cells.

研究动物细胞的细胞分裂机制。

基本信息

批准号：
60065005
负责人：
SAKAI Hikoichi
金额：
$ 118.4万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Specially Promoted Research
财政年份：
1985
资助国家：
日本
起止时间：
1985 至 1989
项目状态：
已结题

项目摘要

[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

【细胞增殖的信号转导机制】：我们证明了在用生长因子或佛波酯刺激培养的哺乳动物细胞后，高分子量微管相关蛋白（MAPS）的磷酸化以及MAP-2激酶的激活（致癌作用的启动子），并进一步鉴定了不磷酸化组蛋白或酪蛋白而仅磷酸化MAP-2和髓鞘碱性蛋白的蛋白激酶，被证明是一种新发现的蛋白激酶。我们进一步证明，由微管破坏药物产生的微管分解直接发出细胞增殖信号，而无需生长因子或佛波酯的刺激。这些结果有力地表明，MAP-2激酶参与了细胞增殖信号转导中的磷酸化级联反应，并证明微管细胞骨架与信号转导直接相关，提出了新的机制概念。[有丝分裂器的形成机制] ...更多信息我们鉴定了centrasons的主要蛋白质成分，51-kD蛋白，并证明了它在存在一些次要成分的对照体和微管蛋白的情况下的aster形成能力。该蛋白质的等电点为9.8，为碱性蛋白质，具有结合鸟嘌呤核苷酸、GTP和GDP的能力，被证明是G蛋白。此外，我们证明了GTP和GDP之间的相互转换绑定到51-kD的蛋白质，和GTP形式的蛋白质是称职的微管组装的信号蛋白。这为有丝分裂器的形成机制提供了一个新的观点，即<double arrow>51 kD蛋白质位点的GTP-GDP相互转换决定了对照体启动微管形成星形和纺锤体的能力。事实上，我们证明了与GTP饱和的分离的中心体片段（具有与GTP饱和的51-kD蛋白）可以比与GDP饱和的那些更有效地启动星形微管。【切割信号的转导机制】：我们纯化了驱动蛋白，并对其酶学性质进行了表征。我们进一步分离纯化了一个260 kD的蛋白质，它定位于细胞膜下，与收缩环中的肌动蛋白束共定位。260 kD蛋白在体外形成卷曲的粗肌动蛋白束。此外，一个重要的发现是，WGA标记的跨膜糖蛋白作为前体结构，通过裂解信号的作用沿着预测的收缩环沿着组装，这被证明是依赖于微管，可能是星形微管。少