Biochemistry and Regulation of Cadherin Activity

描述（由申请人提供）：钙粘蛋白是对组织形成和组织至关重要的细胞粘附分子，其正常功能是防止疾病中组织变性所必需的。钙粘蛋白响应发育和生理信号对黏附功能的由内向外调节在组织形态发生过程中控制细胞间的动态相互作用中起关键作用。虽然已经研究了控制钙粘蛋白的细胞质信号，但对细胞外粘附结构域的功能是如何调节的知之甚少；部分原因是钙粘蛋白粘接键的结构仍未完全了解。非洲爪蟾（Xenopus laevis）早期胚胎中的c -钙粘蛋白是阐明钙粘蛋白由内向外调控机制的一个很好的模型。c -钙粘蛋白的调节是对生长因子的反应，是细胞重排和形态发生运动（称为趋同延伸）所必需的，这种运动驱动胚胎的原肠胚形成和神经发育。C-cadherin整个胞外结构域的晶体结构已经被解开，C-cadherin的亲同型粘接结合特性也通过生物物理测量得到了广泛的分析；支持几种不同的亲同键分子模型。该项目的主要目标是阐明C-cadherin亲同键的结构，确定C-cadherin内向调控的分子机制，并开发可用于研究C-cadherin调控在胚胎形态发生运动控制中的作用的工具。该项目的具体目标是：1)确定形成亲同性相互作用位点的c -钙粘蛋白的特定区域；2)确定C-cadherin在爪蟾胚胎中粘附活性的调控涉及哪些功能区域和蛋白相互作用；3)利用状态或构象特异性抗体作为探针，分析C-cadherin亲同结合活性的调控机制；4)利用定量荧光成像技术确定c -钙粘蛋白在细胞表面的结合特性和组织在内外信号传递过程中的变化。这些研究将有助于我们进一步了解钙粘蛋白在胚胎发生和器官稳态过程中组织形态发生中的功能，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.