Wee Kinases and the Control of the Meiotic Cell Cycle

 描述(由申请人提供)：本提案的总体目标是了解控制进入和退出减数分裂细胞周期的机制。了解生殖细胞减数分裂复制的调控有助于确定细胞如何分裂。关于蛋白质磷酸化的级联反应的基本概念，以及监测关键事件的完成和延缓进展到下一阶段的检查点，主要来自对减数分裂的研究。这一知识提供了对发育和疾病过程的更好理解，并开启了针对细胞周期调节的药理学的新篇章。通过研究小鼠卵母细胞减数分裂进程的调节，我们已经确定了哺乳动物减数分裂成熟所必需的新成分。最重要的是，我们提供的证据表明，在小鼠卵母细胞进入中期I(MI)和退出第二中期(MII)的过程中，磷酸化网络与蛋白质降解一样重要。我们现在建议通过以下三个具体目标组织实验，以进一步了解这些途径是如何参与细胞周期的不同步骤的。第一个具体目标是，我们将调查 激活和抑制蛋白激酶(Wee1B)的磷酸化，我们已经证明它在卵母细胞减数分裂的不同阶段是关键的。我们将检验这一假设，即心肌梗死期间Thi酶的活性是通过抑制部位的磷酸化而受到抑制的。第二个具体目标将致力于了解在MII被捕期间，激酶/磷酸酶如何产生和维持磷酸化网络，以及MII退出是如何被这些网络中的变化触发的。有了第三个具体目标，我们将研究蛋白质稳定性和翻译调控 有助于组装和维护参与MII逮捕和MII退出的这些激酶/磷酸酶网络。更好地理解这些过程将为减数分裂细胞周期的调控提供新的见解，并为未能退出减数分裂可能导致染色体异常转移、分离和胚胎发育受损提供线索。它还将识别新的调控网络，这些网络可以通过药理学的靶向来操纵细胞复制。

 DESCRIPTION (provided by applicant): The overall aim of this proposal is to understand the mechanism that controls entry and exit from the meiotic cell cycle. Understanding the regulation of the germ cell meiotic replication has been instrumental in defining how cells divide. Basic concepts on the cascade of protein phosphorylation that relays a cell through different phases of division, and the checkpoints that monitor completion of critical events and delay progression to the next stage, come largely from studies on meiosis. This knowledge has provided a better understanding of processes involved in development and disease, and has opened a new chapter of pharmacology that targets cell cycle regulators. By investigating the regulation of meiotic progression in mouse oocytes, we have identified novel components essential for meiotic maturation in mammals. Most importantly, we have provided evidence that networks of phosphorylation are as important as protein degradation in the control of entry into metaphase I (MI) and exit from the second metaphase (MII) in mouse oocytes. We now propose to further understand how these pathways are involved in different steps of the cell cycle with experiments organized along the following three Specific Aims. With the first Specific Aim, we will investigate stimulatory and inhibitory phosphorylation of a kinase (Wee1B) which we have shown to be critical at different steps of oocyte meiosis. We will test the hypothesis that the activity of thi enzyme is repressed during MI via phosphorylation at inhibitory sites. The Second Specific aim will be devoted to understanding how kinases/phosphatases generate and maintain networks of phosphorylation during MII arrest and how MII exit is triggered by changes in these networks. With the third Specific Aim, we will investigate how protein stability and translational regulation contribute to assemble and maintain these networks of kinases/phosphatases involved in MII arrest and MII exit. A better understanding of these processes will provide novel insight into the regulation of the meiotic cell cycle and clues on how failure to exit meiosis may lead to aberrant chromosome trafficking, segregation, and compromised embryo development. It will also identify new regulatory networks that can be pharmacologically targeted to manipulate cell replication.