Functional analysis of ERM proteins in epithelial morphogenesis

描述(由申请人提供)：形成由独特的跨膜蛋白、相关细胞质蛋白和磷脂组成的特化膜结构域的能力是极化上皮细胞的基本特性。膜结构域，如顶端表面或连接复合体，允许在质膜上对极化上皮所必需的功能进行空间分离。这个过程的中心是在细胞膜的细胞质一侧形成蛋白质复合体，它定位跨膜蛋白，调节它们的信号输出，并通过调节内吞作用来控制它们的丰度。Ezrin、Radioxin、Moesin(ERM)蛋白在这一过程中起着关键作用。在这项提案中，我们描述了旨在利用两位研究人员Andrea McClatchey(哈佛大学/麻省理工学院)和Richard Fehon(芝加哥大学)的综合专业知识来扩展我们对ERM功能的理解的实验。研究人员和他们的实验室汇集了两个强大的实验系统--老鼠和果蝇--的专业知识。这项拟议的研究采用了多方面的方法，包括遗传学、生物化学、细胞生物学和蛋白质组学，以更好地了解这些高度保守的蛋白质的功能。具体地说，我们计划：1)确定在发育中的上皮细胞中将ERM蛋白与Rho激活状态联系起来的分子机制。2)研究调节ERM活动的分子机制，特别是在ERM活动如何动态调节的背景下。3)阐明ERM蛋白在细胞中的功能：细胞连接重塑。4)建立ERM介导的复合体形成的完整模型。这些实验有望为ERM蛋白在生物过程中的功能提供新的见解，如顶端-基底极性细胞骨架调节，肠腔形成和稳态，以及转移。他们还应该更好地理解在极化细胞中建立特殊膜域的细胞过程，并帮助我们理解细胞骨架和连接动力学在形态发生和疾病中的作用。

DESCRIPTION (provided by applicant): The ability to form specialized membrane domains composed of unique sets of transmembrane proteins, associated cytoplasmic proteins, and phospholipids, is a fundamental property of polarized epithelial cells. Membrane domains, such as the apical surface or junctional complex, allow spatial segregation of functions at the plasma membrane that are essential for polarized epithelia. Central to this process is the formation of protein complexes on the cytoplasmic side of the membrane that localize transmembrane proteins, regulate their signaling output and control their abundance via regulated endocytosis. The Ezrin, Radixin, Moesin (ERM) proteins organize a key role in this process. In this proposal we describe experiments designed to take advantage of the combined expertise of two investigators, Andrea McClatchey (Harvard/MGH) and Richard Fehon (University of Chicago), to extend our understanding of ERM function. The investigators and their laboratories bring together expertise in two powerful experimental systems, the mouse and Drosophila. The proposed research utilizes a multifaceted approach, including genetics, biochemistry, cell biology and proteomics to better understand the functions of these highly conserved proteins. Specifically, we plan to: 1) Determine the molecular mechanisms that link the ERM proteins to the activation state of Rho in developing epithelial cells. 2) Examine the molecular mechanisms that regulate ERM activity, particularly in the context of how ERM activity is dynamically regulated. 3) Delineate the function of the ERM proteins in cell:cell junction remodeling. 4) To build an integrated model of ERM-mediated complex formation. These experiments are expected to provide novel insight into the functions of ERM proteins in biological processes such as apical-basal polarity cytoskeletal regulation, intestinal lumen formation and homeostasis, and metastasis. They should also yield a better understanding of the cellular processes that establish specialized membrane domains in polarized cells, and inform our understanding of cytoskeletal and junctional dynamics during morphogenesis and in disease.