Regulation and function of the Clp 1p protein phosphatase

描述（由申请方提供）：细胞周期蛋白依赖性激酶（CDK）的及时激活和失活调节大多数细胞周期转换。每个细胞周期步骤与其他步骤的精确协调对于细胞正确地将完整的基因组传递到每个子细胞至关重要。如果不这样做，可能会导致多倍体，基因组不稳定和癌症。逆转CDK作用的磷酸酶的功能还不太清楚。高度保守的Cdc 14-家族磷酸酶起逆转Cdk磷酸化事件的作用。我们对Cdc 14磷酸酶的了解大多来自酵母。关于这个磷酸酶家族的关键未回答的问题是它们如何被调节，它们的靶点是什么，以及磷酸酶如何调节这些靶点以促进有丝分裂和胞质分裂的关键步骤。我们一直在研究裂变酵母Cdc 14同源物，称为Clp 1。我们之前的工作表明，Clp 1的活性与其他关键细胞周期调节因子的活性密切相关。此外，我们发现，Clp 1是必要的，以促进适当的染色体分离，胞质分裂，并在有丝分裂结束时Cdk 1的失活。这些研究已经确定了Clp 1参与这些重要步骤的潜在靶点。在这个建议中，我们将利用这些结果来定义在分子方面如何Clp 1的调节，以及它如何发挥作用，以促进染色体分离，胞质分裂，和Cdk 1失活。Clp 1参与细胞周期进程中的这些不同步骤，使Clp 1成为控制关键细胞周期事件和促进基因组稳定性的中心调节因子。我们的具体目标是：1）为了检验正确的染色体分离需要在Survivin和INCENP的Cdk 1磷酸化和Clp 1去磷酸化之间仔细调节平衡的模型。2)为了验证Sid 2激酶和14-3-3蛋白Rad 24如何维持Clp 1活性升高直至胞质分裂完成的假设。3)检验Clp 1通过影响Cdc 15促进肌动球蛋白环稳定性的假设。4)确定Clp 1和后期促进复合物如何促进Cdc 25在有丝分裂晚期失活。

DESCRIPTION (provided by applicant): Timely activation and inactivation of Cyclin dependent kinases (CDKs) regulate most cell cycle transitions. Precise coordination of each cell cycle step with the others is essential for cells to correctly transmit an intact genome to each daughter cell. Failure to do so can lead to polyploidy, genomic instability and cancer. The function of phosphatases which reverse the action of CDKs is less well understood. The highly conserved Cdc14-family phosphatases act to reverse Cdk phosphorylation events. Most of our knowledge about Cdc14 phosphatases has come from yeast. Key unanswered questions about this family of phosphatases are how they are regulated, what are their targets, and how does the phosphatase regulate these targets to promote key steps of mitosis and cytokinesis? We have been studying the fission yeast Cdc14 homolog, known as Clp1. Our work previous work showed that Clp1 activity is closely integrated with the activities of other key cell cycle regulators. In addition, we found that Clp1 is required to promote proper chromosome segregation, cytokinesis, and inactivation of Cdk1 at the end of mitosis. These studies have identified potential targets for Clp1 involved in each of these important steps. In this proposal we will exploit these results to define in molecular terms how Clp1 is regulated, and how it acts to promote chromosome segregation, cytokinesis, and Cdk1 inactivation. The involvement of Clp1 in these various steps in cell cycle progression makes Clp1 a central regulator for controlling key cell cycle events and promoting genomic stability. Our specific aims are: 1) To test the model that proper chromosome segregation requires a carefully regulated equilibrium between Cdk1 phosphorylation and Clp1 dephosphorylation of Survivin and INCENP. 2) To test a hypothesis for how the Sid2 kinase and the 14-3-3 protein, Rad24, maintain elevated Clp1 activity until cytokinesis is complete. 3) To test a hypothesis that Clp1 promotes actomyosin ring stability through effects on Cdc15. 4) To determine how Clp1 and the anaphase promoting complex promote Cdc25 inactivation in late mitosis.