Biochemistry and Regulation of Cadherin Activity

描述（由申请人提供）：钙粘蛋白是对组织的形成和组织化很重要的细胞粘附分子，其适当的功能对于防止疾病中的组织变性是必要的。钙粘蛋白的粘附功能响应于发育和生理信号的由内而外的调节在控制组织形态发生过程中细胞之间的动态相互作用中起着关键作用。虽然细胞质信号控制钙粘蛋白已被研究，很少有人知道细胞外粘附结构域的功能是如何调节的，部分原因是钙粘蛋白粘附键的结构仍然没有完全理解。阐明钙粘蛋白由内而外调节机制的一个很好的模型是蛙非洲爪蟾早期胚胎中的C-钙粘蛋白。C-钙粘蛋白的调节响应于生长因子而发生，并且是细胞重排和形态发生运动所必需的，称为会聚延伸，其驱动胚胎的原肠胚形成和神经胚形成。C-钙粘蛋白的整个细胞外结构域的晶体结构已经得到解决，并且C-钙粘蛋白的嗜同性粘附结合特性已经通过生物物理测量进行了广泛的分析;支持嗜同性键的几种不同的分子模型。该项目的主要目标是阐明C-钙粘蛋白的结构，确定C-钙粘蛋白由内而外调节的分子机制，并开发可用于研究C-钙粘蛋白调节在胚胎形态发生运动控制中的作用的工具。本项目的具体目标是：1）确定C-cadherin中形成嗜同性结合位点的特定区域; 2）确定C-cadherin中哪些功能区域和蛋白质相互作用参与调节其在爪蟾胚胎中的粘附活性; 3）以状态或构象特异性抗体为探针，分析C-cadherin的嗜同性结合活性调节机制;以及4）使用定量荧光成像来确定在由内而外信号传导期间细胞表面上的C-钙粘蛋白的结合性质和组织如何变化。这些研究将有助于提高我们对钙粘蛋白在胚胎发育和器官稳态过程中组织形态发生中的功能的理解，以及钙粘蛋白功能障碍在癌症和出生缺陷等疾病中的作用。

DESCRIPTION (provided by applicant): Cadherins are cell adhesion molecules important for the formation and organization of tissues, and their proper functions are necessary to prevent tissue degeneration in disease. Inside-out regulation of the adhesive function of cadherins in response to developmental and physiological signals plays a key role in controlling the dynamic interactions between cells during tissue morphogenesis. Although cytoplasmic signals controlling cadherins have been studied, very little is known about how the function of the extracellular adhesive domain is regulated; in part because the structure of the cadherin adhesive bond is still not entirely understood. An excellent model for elucidating the mechanism of cadherin inside-out regulation is C-cadherin in early embryos of the frog Xenopus laevis. Regulation of C-cadherin occurs in response to growth factors and is required for cell rearrangements and morphogenetic movements, called convergent-extension, that drive gastrulation and neurulation of the embryo. The crystal structure of the entire extracellular domain of C-cadherin has been solved and the homophilic adhesive binding properties of C-cadherin have been extensively analyzed by biophysical measurements; supporting several distinct molecular models of the homophilic bond. The major objectives of the proposed project are to elucidate the structure of the C-cadherin homophilic bond, to determine the molecular mechanisms underlying the insideout regulation of C-cadherin, and to develop tools that can be used to study the role of C-cadherin regulation in the control of morphogenetic movements in the embryo. The specific aims of the project are to: 1) determine the specific regions of C-cadherin that form the homophilic interaction sites; 2) determine which functional regions and protein interactions of C-cadherin are involved in the regulation of its adhesive activity in the Xenopus embryo; 3) use state or conformation specific antibodies as probes to analyze the mechanisms regulating the homophilic binding activity of C-cadherin; and 4) use quantitative fluorescence imaging to determine how the binding properties and organization of C-cadherin on the cell surface change during inside out signaling. These studies should help improve our understanding of the functions of the cadherins in tissue morphogenesis during embryogenesis and organ homeostasis, and the role of cadherin dysfunction in diseases such as cancer and birth defects.