Molecular regulation of abscission

概述： 成功的细胞分裂和稳定的基因组的维持需要称为细胞周期的不同细胞过程的协调的时空调节。细胞周期进程依赖于不同的细胞周期蛋白激酶（CDK）复合物的交替表达和降解。 细胞周期的最后阶段是胞质分裂结束时的分裂过程，此时两个新细胞物理分离。这一过程由授权检查点进行管理。这个检查点的关键是阻断解离的激酶Aurora B的活性。如何克服极光B活动来驱动极光尚不清楚。然而，我们已经发现了一种新的有丝分裂特异性细胞周期蛋白-CDK复合物，细胞周期蛋白L-CDK 11 p58，其活性是在极光B活性存在下及时终止所需的。CDK 11 p58不关闭Aurora B活性，表明阻断检查点被克服而不是终止以促进有丝分裂进程。 假设：CDK 11活性通过完成先前的细胞周期事件来调节，以通过对抗极光B激酶的抑制活性来促进裂解机制的及时组装。 具体目标： 目的1确定CDK 11 p58如何促进凋亡 我们的数据表明，CDK 11 p58和PP 2A磷酸酶-B56 p58作为解离位点组装的正效应子，而Aurora B是该途径的负效应子。我们将确定： A）使用生物化学和成像测定，PP 2A磷酸酶-B56激酶和CDK 11如何对抗极光B活性以调节ESCRT-III在凋亡中的功能。 B）使用生物化学测定鉴定参与解离的CDK 11 p58底物。 AIM 2确定CDK 11 p58是如何调节的 分裂检查点对染色质在细胞动力学机制中的持续存在、DNA复制应力、分裂细胞之间的核膜重组张力敏感。这些过程如何将信号传递给发射机尚不清楚。 我们将确定： A）细胞周期蛋白L-CDK 11 p58在解离过程中的相互作用，以确定它如何靶向解离机制。 B）使用基于生化和显微镜的测定，哪些先前的细胞周期途径调节CDK 11 p58活性。 总结： 在高等真核生物中，细胞分裂的最后阶段，即分裂，只有当基因组的每个拷贝被分离到分裂母细胞的两极并被包裹在功能性核膜中时才能进行。我们的研究将确定和表征新的途径，以确保细胞分裂的最后一步在正确的时间发生，从而保持具有稳定基因组的活细胞。

OVERVIEW: Successful cell division and the maintenance of a stable genome requires a coordinated spatio-temporal regulation of diverse cellular processes termed the cell cycle. Cell cycle progression relies on the alternate expression and degradation of distinct cyclin-kinase (CDK) complexes. The final stage of the cell cycle is the process of abscission at the end of cytokinesis when the two new cells physically separate. This process is regulated by the abscission checkpoint. Key to this checkpoint is the activity of the kinase Aurora B that blocks abscission. How Aurora B activity is overcome to drive abscission is not known. However, we have discovered a novel mitosis-specific Cyclin-CDK complex, Cyclin L-CDK11p58 whose activity is required for timely abscission in the presence of Aurora B activity. CDK11p58 does not switch off Aurora B activity, suggesting that the abscission checkpoint is overcome rather than terminated to promote mitotic progression. HYPOTHESIS: CDK11 activity is regulated by the completion of prior cell cycle events to promote timely assembly of the abscission machinery by opposing the inhibitory activity of Aurora B kinase. SPECIFIC AIMS: AIM1 Determine how CDK11p58 promotes abscission Our data suggests CDK11p58 and a PP2A phosphatase-B56 epsilon operate as positive effectors of abscission site assembly whereas Aurora B is a negative effector of the pathway. We will determine: A) How PP2A phosphatase-B56 epsilon and CDK11 oppose Aurora B activity to regulate ESCRT-III function in abscission using biochemical and imaging assays. B) Identify CDK11p58 substrates involved in abscission using biochemical assays. AIM2 Determine how CDK11p58 is regulated The abscission check point is sensitive to chromatin persisting in the cytokinetic machinery, DNA replication stress, nuclear envelope reassembly tension between the dividing cells. How these processes transmit signals to the abscission machinery is unknown. We will determine: A) Cyclin L-CDK11p58 interactors during the abscission process to determine how it is targeted to the abscission machinery. B) Which prior cell cycle pathways regulate CDK11p58 activity using biochemical and microscopy based assays. SUMMARY: In higher eukaryotes, the final stage of cell division, abscission, can only proceed once each copy of the genome has been segregated to opposite poles of the dividing mother cell and encased in a functional nuclear envelope. Our studies will identify and characterize new pathways that ensure that the final step in cell division occurs at the correct time thereby maintaining viable cells with a stable genome.