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Molecular and morphological analyses of the initiation of cyclin B translation during oocyte maturation

卵母细胞成熟过程中细胞周期蛋白 B 翻译起始的分子和形态学分析

基本信息

批准号：
14340258
负责人：
YAMASHITA Masakane
金额：
$ 8.26万
依托单位：
Hokkaido University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2005
项目状态：
已结题

项目摘要

Oocyte maturation is triggered by the maturation-promoting factor (also known as the M-phase-promoting factor) (MPF) that consists of Cdc2 and Cyclin B. Synthesis of Cyclin B by translational activation of the dormant mRNA stored in oocytes is required for normal progression of maturation. In this study, we investigated the signal transduction pathways to cyclin B translation, the mechanisms of translational activation, and the action mechanisms of MPF.We examined the involvement of phosphatidylinositol 3-kinase (PI3K) and protein kinase B (PKB) in progesterone-induced Rana oocyte maturation. The obtained results suggest that PI3K, but not PKB, functions during the signal transduction pathway. To know the initiation mechanisms of cyclin B translation, we investigated Pumilio and cytoplasmic polyadenylation element-binding protein (CPEB), and suggested that Pumilio acts as a specific regulator that determines the timing of translational activation of cyclin B mRNA by its release from ph … More osphorylated CPEB during oocyte maturation.Investigations into the functions of Cyclins B1 and B2 using Rana oocytes provide evidence of the requirement of Cyclin B2, but not Cyclin B1, for organizing the bipolar spindle, though either Cyclin B1 or B2 is redundant for inducing germinal vesicle breakdown and chromosome condensation. MPF and mitogen-activated protein kinase (MAPK) are involved in the morphological changes that occur during maturation, but their precise roles are unknown. Using Rana oocytes, we clarified the functions of MPF and MAPK in each process of sequential morphological changes during oocyte maturation.Gamma-tubulin is essential for nucleation of microtubules at centrosomes, but little is known about its role during spindle formation in oocytes. We observed the behavior of gamma-tubulin during spindle formation in Xenopus oocytes, and found that gamma-tubulin is probably translocated by dynein to regulate microtubule organization leading to spindle formation. Significance of gamma-tubulin in spindle pole formation is also demonstrated by overexpression experiments. Less

卵母细胞成熟由成熟促进因子（也称为M期促进因子）（MPF）触发，该因子由Cdc 2和细胞周期蛋白B组成。细胞周期蛋白B的合成是卵母细胞正常成熟所必需的。本研究探讨了细胞周期蛋白B翻译的信号转导途径、翻译激活机制以及MPF的作用机制，并研究了磷脂酰肌醇3-激酶（PI 3 K）和蛋白激酶B（PKB）在孕酮诱导蛙卵母细胞成熟中的作用。结果表明，PI 3 K，而不是PKB，在信号转导通路中发挥作用。为了了解细胞周期蛋白B翻译的起始机制，我们研究了Pumilio和细胞质多聚腺苷酸化元件结合蛋白（CPEB），并提出Pumilio作为一种特异性调节剂，通过其从pH值释放来决定细胞周期蛋白B mRNA翻译激活的时间。 ...更多信息使用蛙卵母细胞对细胞周期蛋白B1和B2的功能进行的调查提供了细胞周期蛋白B2而不是细胞周期蛋白B1对于组织双极纺锤体的需要的证据，尽管细胞周期蛋白B1或B2对于诱导生殖囊泡破裂和染色体凝聚是多余的。MPF和丝裂原活化蛋白激酶（MAPK）参与了成熟过程中发生的形态学变化，但它们的确切作用尚不清楚。以蛙卵母细胞为研究对象，阐明了MPF和MAPK在卵母细胞成熟过程中各个形态学变化过程中的作用。γ-微管蛋白是中心体微管成核所必需的，但在卵母细胞纺锤体形成过程中的作用却知之甚少。我们观察了非洲爪蟾卵母细胞中γ-微管蛋白在纺锤体形成过程中的行为，发现γ-微管蛋白可能被动力蛋白转位以调节微管组织，从而导致纺锤体的形成。γ-微管蛋白在纺锤体极形成中的重要性也通过过表达实验证明。少