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要求每个细胞接受相同数量的遗传物质（DNA），而且还要求细胞的其他成分被平均分割。物理分离两个子细胞的过程被称为细胞质分裂，这个过程包括一个收缩环，它物理地收缩细胞并将其分裂成两个。细胞质分裂利用许多相同的机制来调节迁移过程中细胞形状的变化。细胞形状取决于主要由肌动蛋白组成的动态结构（细胞骨架），其行为受许多小信号分子的调节。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。该项目将研究这些小信号分子对细胞骨架的调节，并有助于阐明它们的作用机制。这项研究将为本科生和研究生提供培训和教育机会，并共同努力招收包括美国印第安人和西班牙裔学生在内的少数民族学生。还将向高中推广，目的是培养学生对科学的长期兴趣。在这个项目中，分子和药理学试剂工具箱将结合生物物理测量和高分辨率光学和电子显微镜来研究G蛋白Rho， Rac和Cdc42如何协调大胚胎细胞中细胞动力学相关的形状变化。目标1和目标2将结合使用活细胞成像和生物物理分析来确定Rac和Cdc42信号的哪些元素可以拮抗rho依赖性细胞分裂。Aim 3将利用可收缩环的独特制备来定义其3D结构，并确定Rho信号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细胞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，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.