Positioning the Plane of Cell Division during Cytokinesis

描述（由申请人提供）：成功的细胞分裂需要对细胞骨架进行精确的空间和时间控制，以便在分离的姐妹染色单体之间形成向内的卵裂沟。收缩环的组装发生在细胞皮质，细胞质区域并列的质膜。这一过程的主要调节因子，小GTdR RhoA，在赤道细胞皮层被激活的机制并不清楚。 很好理解。已经获得了新的证据，揭示了以前未被识别的抑制机制。初步结果表明，这种抑制机制的表征将提供深入了解如何交换因子促进RhoA激活。这些结果和证据从各种系统提出了一个假设，其中质膜靶向鸟嘌呤核苷酸交换因子是激活GTP酶途径的关键步骤，一旦激活，GTP酶的主要功能是招募效应器到适当的膜环境。这一假设将在胞质分裂的背景下使用最近开发的光遗传学工具进行直接测试，该光遗传学工具使用光来控制活细胞中的蛋白质定位和功能。最后，将进行实验以揭示一种新型含GYF结构域的蛋白质的分子功能，该蛋白质调节RhoA依赖性皮质收缩性。

DESCRIPTION (provided by applicant): Successful cell division requires exquisite spatial and temporal control of the cytoskeleton such that the ingressing cleavage furrow forms between the separating sisters chromatids. Contractile ring assembly occurs in the cell cortex, the cytoplasmic region juxtaposed to the plasma membrane. The mechanism by which the master regulator of this process, the small GTPase RhoA, is activated at the equatorial cell cortex is not well understood. New evidence has been obtained that reveals a previously unidentified inhibitory mechanism. Preliminary results suggest that characterization of this inhibitory mechanism will provide insights into how exchange factors promote RhoA activation. These results and evidence from a variety of systems suggest a hypothesis in which plasma membrane targeting of guanine nucleotide exchange factors is a key step in activating GTPase pathways and that, once active, the primary function that GTPases serve is to recruit effectors to the appropriate membrane environment. This hypothesis will be directly tested in the context of cytokinesis using recently developed optogenetic tools that affords control of protein localization and function in living cells using light. Lastly, experiments will be performed to uncover the molecular function of a novel GYF-domain containing protein that regulates RhoA-dependent cortical contractility.