Regulation of cytokinesis

描述(申请人提供)：细胞质分裂，一个细胞分裂成两个子细胞，是细胞繁殖周期的最后阶段，也是最不为人所知的。正确计时胞质分裂过程，使其仅在染色体复制和分离之后发生，对于防止灾难性的基因组不稳定是必要的，因此，胞质分裂与细胞周期的其他事件相一致地受到严格调控。我们使用胞质分裂研究的领先模式生物--裂殖酵母庞贝，在鉴定和鉴定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蛋白质如何协同工作，并在细胞周期控制下介导成功的细胞分裂。我们将集中讨论两种必需的、保守的蛋白质，它们是组装基于肌球蛋白的收缩环所必需的，该环用于将细胞夹在两个--cdc15和cdc12中。CDC15是收缩装置的支架，它通过其F-bar结构域将肌球蛋白收缩环连接到质膜上。我们发现，在有丝分裂进入阶段时，CDC15的整体去磷酸化诱导了蛋白质的构象转换，使其能够寡聚，结合膜，并作为稳定的膜锚定支架进行细胞动态环组装。我们现在将确定CDC15如何与膜相互作用，它如何齐聚形成支架结构，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对膜的分裂位置产生影响。我们将研究在胞质分裂过程中，CDC15如何与第二个F-bar蛋白协调，以实现膜与肌动蛋白聚合之间的适当耦合。CDC12是使收缩环的F-肌动蛋白成核的福尔马林。福尔马林是如何进行胞质分裂的也不完全清楚，我们将测试这一假设，即细胞动福尔曼CDc12的瞬时有丝分裂磷酸化可以解除其自身抑制，从而使其在正确的细胞周期阶段准确发挥作用。我们将用蛋白质组学和大规模遗传筛选来补充这些重点机制研究，旨在建立细胞质分裂成分的功能相互作用网络。尽管某些细节在不同的生物体中会有所不同，但这些研究将对理解细胞质分裂是如何在包括人类在内的多种物种中协调进行的产生重大影响。 与公共卫生相关：正确安排胞质分裂过程的时间，使其仅在染色体复制和分离之后发生，这对于防止灾难性的基因组不稳定是必要的。我们已经揭示了控制细胞动态环形成的主要机制，对这一关键机制的进一步了解将影响旨在操纵细胞周期事件协调的癌症治疗药物的寻找。

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. PUBLIC HEALTH RELEVANCE: Correctly timing the process of cytokinesis so that it occurs only after chromosome replication and segregation is necessary to prevent catastrophic genomic instability. We have uncovered a primary mechanism that governs when the cytokinetic ring forms and a further understanding of this key mechanism will influence the search for cancer therapeutics aimed at manipulating the coordination of cell cycle events.