Regulation of cytokinesis

描述（由申请人提供）：胞质分裂，即一个细胞物理分裂为两个子细胞，是细胞生殖周期的最后阶段，也是人们了解最少的阶段。正确地定时胞质分裂的过程，使其仅在染色体复制和分离后发生，是防止灾难性的基因组不稳定性所必需的，因此，胞质分裂与细胞周期的其他事件一起严格调节。我们已经取得了显着的进展，在确定和表征蛋白质的胞质分裂所必需的胞质分裂研究的领先模式生物，裂殖酵母粟酒裂殖酵母。我们现在建议更好地了解这些无数的蛋白质如何在细胞周期控制下共同工作，以介导成功的细胞分裂。我们将集中在两个基本的，保守的蛋白质，这是必要的组装肌动球蛋白为基础的收缩环，用于捏细胞在两个- 1）Cdc 15和2）Cdc 12。Cdc 15是收缩器的支架，它通过其F-BAR结构域将肌动球蛋白收缩环连接到质膜。我们发现，批量去磷酸化Cdc 15在有丝分裂进入诱导蛋白质，使其寡聚化，结合膜，并作为一个稳定的膜锚定支架细胞动力学环组装的构象开关。我们现在将确定Cdc 15如何与膜相互作用，它如何寡聚形成支架结构，以及它如何在新获得的F-BAR结构域的X射线晶体结构指导下影响分裂位点的膜。我们将研究Cdc 15是如何与第二个F-BAR蛋白协调，以实现胞质分裂过程中膜和肌动蛋白聚合之间的适当耦合。Cdc 12是使收缩环的F-肌动蛋白成核的酶。formins如何部署胞质分裂也不完全理解，我们将测试的假设，瞬时有丝分裂磷酸化的细胞动力学的Cdc 12缓解其自身抑制，使其功能准确地在正确的细胞周期阶段。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，旨在建立胞质分裂组分的功能相互作用网络。虽然生物体之间的一些细节会有所不同，但这些研究将对理解胞质分裂如何在包括人类在内的多个物种中协调产生重大影响。

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.