COLLABORATIVE RESEARCH: 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获得相等数量的遗传物质(DNA)，而且还要求细胞的其他内容被平均分割。物理分离两个子细胞的过程被称为胞质分裂，这个过程涉及一个收缩环，该环物理上收缩细胞并将其一分为二。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。细胞的形状依赖于一个动态的结构(细胞骨架)，该结构主要由肌动蛋白组成，其行为受一些小信号分子的调节。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来控制细胞骨架，但这些模型的解释能力还没有明确确立。这个项目将研究这些小信号分子对细胞骨架的调节，并帮助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，并共同努力招收代表不足的少数族裔，包括土著美国印第安人和西班牙裔学生。此外，还将扩展到高中，目的是激发学生对科学的长期兴趣。在这个项目中，一个分子和药理试剂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如何协调大型胚胎细胞中与胞质分裂相关的形状变化。AIMS 1和2将使用活细胞成像和生物物理分析相结合的方法来确定RAC和CDC42信号的哪些元件拮抗Rho依赖的细胞质分裂。Aim 3将利用独特的收缩环制备方法来定义其3D结构，并确定Rho信号的不同元件如何对其组装和功能做出贡献。这些研究的结果将通过扩大我们对肌动蛋白和肌球蛋白II在驱动细胞质分裂的收缩环中的精确3D结构的理解，促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 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.