INTEGRIN/CADHERIN CROSSTALK: SALIVARY GLAND DEVELOPMENT

这项建议的长期目标是确定两种主要的黏附受体--整合素和钙粘附素--在唾液腺发育过程中的功能是如何协调的。整合素将细胞连接到细胞外基质，而钙粘附素则介导细胞间的黏附。在它们的胞内区，这两种类型的受体。形成动态的多蛋白复合体，将它们与肌动蛋白细胞骨架连接起来。通过形成这些复合体，整合素和钙粘附素调节细胞的附着和极性，并在细胞和环境之间传递信号。越来越多的证据表明，整合素和钙粘附素必须受到协调调节，以调节对发育至关重要的细胞相互作用。我们最近的体内研究表明，层粘连蛋白的受体α3beta1在小鼠下颌下腺(SMG)胚胎发育过程中影响E-钙粘附素在细胞-细胞连接中的募集。在缺乏α3beta1整合素的情况下，E钙粘附素在细胞-细胞边界的表达增强，肌动蛋白细胞骨架的组织和分布发生改变，已知的调节肌动蛋白细胞骨架组织的两种Rho GTP酶CDC42和RhoA的表达和膜募集发生切换。我们的假设是SMG的发育需要α3β1整合素和E钙粘附素活性的协调，由信号分子和肌动蛋白细胞骨架介导。。为了验证我们的假设，我们提出了一套综合的实验方法，旨在阐明Alpha3beta1在发育中的小鼠SMG中影响E-钙粘蛋白功能的机制。提出了三个具体的目标：1)确定α3beta1整合素是否调节钙粘素相关蛋白复合体的组成、连环蛋白的酪氨酸磷酸化以及E-钙粘素蛋白复合体与肌动蛋白细胞骨架的相互作用；2)确定通过CDC42和RhoA的信号是否介导E-钙粘素募集到附着连接；以及3)在表达SMG候选信号分子突变形式的转基因小鼠中，验证alpha3beta1整合素对E-钙粘素功能的体内意义。

The long-term goal of this proposal is to determine how the function of two major classes of adhesion receptors, integrins and cadherins, is coordinated during salivary gland development. Integrins link cells to the extracellular matrix, while cadherins mediate intercellular adhesion. At their intracellular domains, both types of receptors. form dynamic multiprotein complexes that connect them to the actin cytoskeleton. Through the formation of these complexes, integrins and cadherins regulate cell attachment and polarity and transmit signals between the cells and their environment. Increasing evidence suggests that integrins and cadherins must be coordinately regulated to mediate cellular interactions essential for development. Our recent in vivo studies indicate that alpha3beta1, a receptor for laminin, affects E-cadherin recruitment to cell-cell junctions during the embryonic development of mouse submandibular gland (SMG). In the absence of alpha3beta1 integrin, E cadherin expression at cell-cell borders is augmented, the organization and distribution of the actin cytoskeleton is altered, and the expression and membrane recruitment of Cdc42 and RhoA, two Rho GTPases known to regulate the organization of the actin cytoskeleton, is switched. Our hypothesis is that SMG development requires coordination of alpha3beta1 integrin and E-cadherin activities, mediated by signaling molecules and the actin cytoskeleton. . To test our hypothesis we propose an integrated set of experimental approaches aimed at elucidating the mechanism via which alpha3beta1 affects E-cadherin function in the developing mouse SMG. Three specific aims are proposed: 1) determining whether alpha3beta1 integrin regulates the composition of cadherin-associated protein complexes, tyrosine phosphorylation of catenins and interaction of E- cadherin protein complexes with the actin cytoskeleton; 2) determining if signaling via Cdc42 and RhoA mediates E-cadherin recruitment to adherens junctions; and 3) validating the in vivo significance of alpha3beta1 integrin effects on E-cadherin function in transgenic mice expressing mutant forms of the candidate signaling molecules in the SMG.