Cadherin Regulation in Dermal Endothelial Cells

描述(由申请人提供)： 皮肤微循环在一系列以表皮过度增殖或皮肤炎为特征的皮肤病中起着核心作用。其中许多疾病的典型特征是血管通透性增加，导致皮肤浮肿和疾病恶化。此外，改变的血管组织和/或新生血管与银屑病、皮肤肿瘤的形成以及伤口愈合过程中的组织重塑有关。相邻内皮细胞之间的黏附相互作用在血管通透性和血管生成过程中内皮细胞的重组和生长中起着核心作用。VE-钙粘附素是一种内皮细胞特有的细胞表面黏附分子，在内皮细胞生长控制、血管屏障功能以及与血管生成相关的形态发生事件中发挥重要作用。VE-cadherin的胞外结构域介导细胞间的接触，而VE-cadherin的胞浆尾巴作为一系列蛋白质的支架，这些蛋白质被称为连接素，将VE-cadherin连接到肌动蛋白和波形蛋白的细胞骨架网络。虽然关于VE-钙粘蛋白与细胞骨架之间的分子相互作用已经发现了很多，但对VE-钙粘蛋白的细胞表面水平是如何调节的还知之甚少。我们实验室的初步数据推测，连环蛋白除了连接钙粘附素与细胞骨架外，还通过调节VE-钙粘附素的内化和降解来调节VE-钙粘附素在质膜上的呈现。提出了三个具体目标。在第一个目标中，将测试连环蛋白p120调节VE-钙粘附素内化和降解的能力。在第二个目的中，将定义钙粘附素连环蛋白复合体在质膜和内细胞室的组装状态。在第三个目标中，VE-cadherin尾巴中针对蛋白质内化的特定序列将通过定点突变被消融，这些突变对内皮屏障功能和分支形态发生的影响将被确定。这些研究的长期目标是确定调节VE-钙粘蛋白细胞表面呈现的分子决定因素，从而揭示在皮肤病背景下可以作为治疗靶点来调节内皮屏障功能和血管生成的过程。

DESCRIPTION (provided by applicant): The cutaneous microcirculation plays a central role in a range of skin diseases that are characterized by epidermal hyperproliferation or cutaneous inflammation. Many of these diseases are typified by increased vascular permeability, leading to cutaneous edema and exacerbation of disease. In addition, altered vascular organization and/or neovascularization are associated with psoriasis, skin tumorigenesis, and with tissue remodeling during wound healing. Adhesive interactions between adjacent endothelial cells play a central role in both vascular permeability and in the reorganization and growth of endothelial cells during angiogenesis. VE-cadherin is a cell surface adhesion molecule specific to endothelial cells which plays a crucial role in endothelial growth control, vascular barrier function and in morphogenic events associated with angiogenesis. The extracellular domain of VE-cadherin mediates cell to cell contact, whereas the cytoplasmic tail of VE-cadherin functions as a scaffold for a series of proteins termed catenins, which couple VE-cadherin to actin and vimentin cytoskeletal networks. Although a great deal has been discovered about the molecular interactions that link VE-cadherin to the cytoskeleton, much less is known about how cell surface levels of VE-cadherin are regulated. Preliminary data from our laboratory leads to the hypothesis that the catenins, in addition to linking cadherins to the cytoskeleton, also regulate VE-cadherin presentation at the plasma membrane by regulating VE-cadherin internalization and degradation. Three specific aims are proposed. In the first aim, the ability of the catenin p120 to regulate VE-cadherin internalization and degradation will be tested. In the second aim, the assembly state of the cadherin catenin complex at the plasma membrane and in the endocytic compartment will be defined. In the third aim, specific sequences in the VE-cadherin tail that target the protein for internalization will be ablated using site directed mutagenesis, and the effect of these mutations on endothelial barrier function and branching morphogenesis will be determined. The long-term goal of these studies is to identify the molecular determinants that regulate VE-cadherin cell surface presentation, and thereby expose processes that could be therapeutically targeted to modulate endothelial barrier function and angiogenesis in the context of cutaneous disease.