COLLABORATIVE RESEARCH/RUI: G Protein Regulation of the Actin Cytoskeleton in the Cleavage Stage Embryo

细胞分裂是几乎所有生命系统的基本过程。两个完全相同的子细胞的产生不仅需要每个细胞接受相等的遗传物质（DNA）补充，而且还需要细胞的其他内容物被平均分配。物理分离两个子细胞的过程称为胞质分裂，这个过程涉及一个收缩环，该收缩环物理收缩细胞并将其一分为二。胞质分裂利用许多相同的机制，用于调节细胞迁移过程中的形状变化。细胞的形状取决于动态结构（细胞骨架），该动态结构主要由蛋白质肌动蛋白组成，并且其行为由许多小信号分子调节。已经提出了几个相互矛盾的模型来解释这些小分子如何相互作用以控制细胞骨架，但这些模型的解释力尚未明确建立。本项目将研究这些小信号分子对细胞骨架的调控，并帮助阐明它们发挥作用的机制。这项研究将为本科生和研究生提供培训和教育机会，并共同努力招募代表性不足的少数民族，包括美洲原住民印第安人和西班牙裔学生。还将在高中开展外联活动，目的是培养学生对科学的长期兴趣。在这个项目中，分子和药理学试剂的工具箱将与生物物理测量和高分辨率光学和电子显微镜相结合，以研究G蛋白Rho，Rac和Cdc42如何协调大胚胎细胞中与胚胎发育相关的形状变化。目标1和2将使用活细胞成像和生物物理分析的组合来确定Rac和Cdc 42信号传导的哪些元素拮抗Rho依赖性胞质分裂。目标3将利用收缩环的独特制备来定义其3D结构，并确定Rho信号传导的不同元素如何有助于其组装和功能。这些研究的结果将通过扩展我们对驱动胞质分裂的收缩环中肌动蛋白和肌球蛋白II的精确3D结构的理解来推进动物细胞分裂研究领域的知识。

Cell division is a fundamental process for virtually all living systems. The generation of two identical daughter cells requires not only that each cell receives an equal complement of genetic material (DNA) but also that the other contents of the cell be divided equally. The process of physically separating the two daughter cells is known as cytokinesis, and this process involves a contractile ring that physically constricts the cell and splits it in two. Cytokinesis utilizes many of the same same mechanisms that are used to regulate cell shape change during migration. Cell shape is dependent on a dynamic structure (the cytoskeleton) that is comprised primarily of the protein actin, and whose behavior is regulated by a number of small signaling molecules. Several conflicting models have been proposed to explain how these small molecules interact to control the cytoskeleton, but the explanatory power of these models has not been clearly established. This project will investigate the regulation of the cytoskeleton by these small signaling molecules and help to clarify the mechanisms by which they function.This research will provide training and educational opportunities for undergraduate and graduate students, with a concerted effort to recruit underrepresented minorities including Native American Indian and Hispanic students. Outreach into high schools will also be performed with the intent to generate in students a long-term interest in science. In this project, a toolbox of molecular and pharmacological reagents will be combined with biophysical measurements and high-resolution light and electron microscopy to examine how the G proteins Rho, Rac, and Cdc42 coordinate cytokinesis-related shape change in large embryonic cells. Aims 1 and 2 will use a combination of live cell imaging and biophysical analyses to determine what elements of Rac and Cdc42 signaling antagonize Rho-dependent cytokinesis. Aim 3 will take advantage of a unique preparation of the contractile ring to both define its 3D structure and determine how the different elements of Rho signaling contribute to its assembly and function. The results of these studies will advance knowledge in the field of animal cell division research by extending our understanding of the precise 3D architecture of actin and myosin II in the contractile ring that drives cytokinesis.