Regulatory Mechanism of M-phase by MPF,M-phase Promoting Factor

MPF、M相促进因子对M相的调节机制

基本信息

批准号：
03405004
负责人：
KISHIMOTO Takeo
金额：
$ 14.02万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (A)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1993
项目状态：
已结题

项目摘要

MPF (M-phase promoting factor), which is composed of the p34^<cdc2>/cyclin B complex, cdc2 kinase, governs M-phase in all eukaryotic cells. In this project, we studied how M-phase is executed by cdc2 kinase, and obtained following results.1.We developed a new method to purify cdc2 kinase at high performance by modifying p13^<sucl>-affinity chromatography. This enabled us to analyze the function of cdc2 kinase in inducing various M-phase events.2.At G2/M-phase border, the inactive form of p34^<cdc2>/cyclin B complex localizes in the cytoplasm. The complex is transformed to active form in the cytoplasm at the transition to M-phase. Thereafter, a part of the complex moves into nucleus, while other associates with mitotic apparatus. These specific localizations of the complex might support its specific function to execute M-phase within a cell.3.In contrast to the previous belief that histone H1 phosphorylation by cdc2 kinase plays a key role in chromosome condensation, condensation occurs normally even in the chromatins lacking histone H1. This suggests the presence of an unknown major target of cdc2 kinase for chromosome condensation other than histone H1.4.The p34^<cdc2/>cyclin B complex associates with a microtubule via the binding between cyclin B component and the prolin-rich region of MAP4. In such a complex, cdc2 kinase phosphorylates MAP4 to decrease its microtubule-stabilizing ability, resulting in increased dynamic instability of an individual microtubule. This effect of cdc2 kinase appears to contribute to form metaphase spindle.

MPF（M 期促进因子）由 p34^<cdc2>/cyclin B 复合物、cdc2 激酶组成，控制所有真核细胞的 M 期。在本项目中，我们研究了cdc2激酶如何执行M期，并获得了以下结果： 1.通过修改p13^<sucl>-亲和层析，我们开发了一种高效纯化cdc2激酶的新方法。这使我们能够分析cdc2激酶在诱导各种M期事件中的功能。2.在G2/M期边界，p34^<cdc2>/cyclin B复合物的非活性形式定位于细胞质。该复合物在过渡到 M 期时在细胞质中转化为活性形式。此后，复合体的一部分进入细胞核，而其他部分则与有丝分裂器结合。该复合物的这些特定定位可能支持其在细胞内执行 M 期的特定功能。 3. 与之前认为 cdc2 激酶导致的组蛋白 H1 磷酸化在染色体浓缩中起关键作用的观点相反，浓缩甚至在染色质中也正常发生缺乏组蛋白 H1。这表明除了组蛋白 H1.4 之外，还存在 cdc2 激酶用于染色体浓缩的未知主要靶标。p34^<cdc2/>细胞周期蛋白 B 复合物通过细胞周期蛋白 B 成分与富含脯氨酸的区域之间的结合与微管相关联。地图4。在这样的复合物中，cdc2 激酶磷酸化 MAP4 以降低其微管稳定能力，导致单个微管的动态不稳定性增加。 cdc2 激酶的这种作用似乎有助于形成中期纺锤体。