p120 Catenin and Endothelial Monolayer Function

内皮细胞屏障功能障碍与多种疾病状态的病因有关 包括动脉粥样硬化、糖尿病引起的微血管通透性过高和 急性肺损伤VE-钙粘蛋白是一种细胞-细胞粘附蛋白，参与调节许多细胞间的粘附。 内皮细胞的功能。VE-钙粘蛋白的胞质结构域结合到哺乳动物的犰狳家族。 连接蛋白形成粘附连接（AJ）。AJ蛋白磷酸化的变化 与调节屏障功能有关。例如，AJ蛋白的磷酸化发生在 在中风和心肌梗死后水肿形成过程中， Src激酶的激活。这项提议集中在p120上，这是一种与VE的质膜结合的连环蛋白， 钙粘蛋白，在那里它对许多蛋白质起支架作用。有趣的是，p120是Src的靶点， 激酶和p120磷酸化状态的改变与内皮屏障的降低有关 炎症介质治疗后的功能。此外，我们最近的出版物显示， p120与VE-钙粘蛋白的相互作用是维持内皮细胞中VE-钙粘蛋白水平所必需的。 细胞在此背景下，我们假设VE-钙粘蛋白的跨膜区域及其相互作用 p120在调节内皮细胞的细胞间粘附和屏障功能中起关键作用 单层。这个假设将通过执行三个具体目标进行研究：1）识别区域 负责维持内皮细胞中的VE-钙粘蛋白水平和屏障功能的VE-钙粘蛋白 细胞单层; 2）确定p120从膜释放时是否作为信号分子 3）鉴定p120调控内皮细胞-细胞间相互作用所需的结构域。 粘附和屏障功能。我们也将使用VE和N-钙粘蛋白嵌合分子的表达 作为p120的缺失突变体进行p120和VE-钙粘蛋白的结构/功能分析及其作用 对内皮细胞-细胞粘附和屏障功能的影响。这些分子的表达将在 不存在将使用siRNA耗尽的内源性钙粘蛋白或p120。这些研究将提供 对控制内皮屏障功能的细胞和分子机制的新见解， 有可能确定新的干预地点。

Dysfunction of the endothelial cell barrier has been implicated in the etiology of a variety of disease states including atherosclerosis, microvascular hyperpermeability with diabetes and pulmonary edema following acute lung injury. VE-cadherin is a cell-cell adhesion protein that participates in the regulation of a number of endothelial cell functions. The cytoplasmic domain of VE-cadherin binds to the armadillo family of proteins called catenins to form the adherens junction (AJ). Changes in the phosphorylation of AJ proteins have been implicated in regulating barrier function. For example, phosphorylation of AJ proteins occurs during the formation of edema following stroke and myocardial infarction, a process that is dependent on activation of Src kinase. This proposalfocuses on p120, a catenin that binds to the juxtamembrane of VE- cadherin where it serves a scaffolding role for a number of proteins. Interestingly, p120 is a target for Src kinase and changes in the phosphorylation state of p120 are associated with decreased endothelial barrier function following treatment with inflammatory mediators. In addition, our recent publications have shown that the interaction of p120 with VE-cadherin is required for maintaining VE-cadherin levels in endothelial cells. Within this context, we hypothesize that the juxtamembrane region of VE-cadherin and its interaction with p120 plays a critical role in regulating cell-cell adhesion and barrier function in endothelial cell monolayers. This hypothesis will be investigated by performing three specific aims: 1) identify the regions of VE-cadherin that are responsible for maintaining VE-cadherin levels and barrier function in endothelial cell monolayers; 2) determine if p120 serves as a signaling molecule when released from the membrane into the cytoplasm; and 3) identify the domains of p120 required for the regulation of endothelial cell-cell adhesion and barrier function. We will use expression of chimeric molecules of VE and N-cadherin as well as deletion mutants of p120 to perform structure/function analysis of p120 and VE-cadherin and their effects on endothelial cell-cell adhesion and barrier function. Expression of these molecules will be performed in the absence of endogenous cadherin or p120 that will be depleted using siRNA. These studies will provide new insights into the cellular and molecular mechanisms controlling endothelial barrier function and potentially identify new sites for intervention.