Regulation of cytokinesis

描述（由申请人提供）：细胞质分裂，一个细胞物理分裂成两个子细胞，是细胞生殖周期的最后阶段，也是最不为人所知的。正确地安排细胞质分裂过程，使其只发生在染色体复制和分离之后，这对于防止灾难性的基因组不稳定是必要的，因此，细胞质分裂与细胞周期的其他事件一起受到严格调节。我们利用分裂酵母裂糖酵母（Schizosaccharomyces pombe）作为细胞质分裂研究的主要模式生物，在鉴定和表征细胞质分裂所必需的蛋白质方面取得了重大进展。我们现在建议更好地了解这些无数的蛋白质是如何在细胞周期控制下协同工作来介导成功的细胞分裂的。我们将重点关注两个基本的、保守的蛋白质，它们是组装一个基于肌动球蛋白的收缩环所必需的，这个收缩环被用来夹住两个细胞- 1)Cdc15和2)Cdc12。Cdc15是收缩装置的支架，它通过其F-BAR结构域将肌动球蛋白收缩环连接到质膜上。我们发现Cdc15在有丝分裂进入处的大量去磷酸化诱导了蛋白质的构象开关，使其能够寡聚，结合膜并作为细胞动力学环组装的稳定的膜锚定支架。我们现在将确定Cdc15如何与膜相互作用，它如何寡聚形成支架结构，以及它如何在F-BAR结构域的新获得的x射线晶体结构指导下影响膜的分裂位点。我们将研究Cdc15如何与第二个F-BAR蛋白协调，以在细胞分裂过程中实现膜和肌动蛋白聚合之间的适当偶联。Cdc12是使收缩环的f -肌动蛋白成核的双胍。formmins如何用于细胞分裂尚不完全清楚，我们将测试一种假设，即细胞动力学formin Cdc12的瞬时有丝分裂磷酸化减轻了其自身抑制作用，从而使其在正确的细胞周期阶段精确地发挥作用。我们将用蛋白质组学和大规模遗传筛选来补充这些集中的机制研究，旨在建立细胞分裂组分的功能相互作用网络。尽管一些细节在不同的生物体之间会有所不同，但这些研究将对理解包括人类在内的多种物种如何协调细胞分裂产生重大影响。

DESCRIPTION (provided by applicant): Cytokinesis, the physical division of one cell into two daughter cells, is the final stage of the cell reproductive cycle and the least well understood. Correctly timing the process of cytokinesis so that it occurs only after chromosome replication and segregation is necessary to prevent catastrophic genomic instability and accordingly, cytokinesis is strictly regulated in concert with other events of the cell cycle. We have made significant progress in identifying and characterizing proteins essential for cytokinesis using a leading model organism for cytokinesis studies, the fission yeast Schizosaccharomyces pombe. We now propose to gain a better understanding of how these myriad proteins work together and under cell cycle control to mediate successful cell division. We will focus on two essential, conserved proteins that are necessary for assembling an actomyosin-based contractile ring that is used to pinch cells in two - 1) Cdc15 and 2) Cdc12. Cdc15 is a scaffold of the contractile apparatus and it links the actomyosin contractile ring to the plasma membrane through its F-BAR domain. We found that bulk dephosphorylation of Cdc15 at mitotic entry induces a conformational switch in the protein that allows it to oligomerize, bind the membrane and act as a stable membrane-anchored scaffold for cytokinetic ring assembly. We will now determine how Cdc15 interacts with membranes, how it oligomerizes to form a scaffold structures, and how it might influence the membrane at the division site guided by a newly obtained X-ray crystal structure of its F-BAR domain. We will study how Cdc15 is coordinated with a second F-BAR protein to achieve the proper coupling between the membrane and actin polymerization during cytokinesis. Cdc12 is the formin that nucleates the F-actin of the contractile ring. How formins are deployed for cytokinesis is incompletely understood also, and we will test the hypothesis that transient mitotic phosphorylation of the cytokinetic formin Cdc12 relieves its autoinhibition so that it functions precisely at the correct cell cycle stage. We will complement these focused mechanistic studies with proteomic and large-scale genetic screens designed to establish a functional interaction network of cytokinesis components. Although some of the details will vary between organisms, these studies will have a major impact for understanding how cytokinesis is orchestrated in multiple species including humans.