Function of a Novel Matrix Junction in Endothelial Cells

描述（由申请人提供）：血管腔内衬有 内皮细胞（EC）。后者位于基底膜上，其结构 元素包括层粘连蛋白、蛋白聚糖和胶原蛋白。 EC 与这些相互作用 基质蛋白部分通过称为整合素的受体。这样的相互作用是 参与调节许多细胞功能，包括粘附、 运动性和基因表达。在成人中，血管中的内皮细胞 是静止的。然而，在伤口愈合和病理条件下 包括癌症和炎症性疾病，刺激会激活新血管 生长，一个称为血管生成的过程。在此应用中，我们的研究是 重点关注我们最近在 EC 中发现的一种新型基质连接。 初步实验表明内皮细胞组装了一个新的焦点 与微丝和微丝相关的接触状结构 波形蛋白细胞骨架。这种波形蛋白相关的基质粘附（VMA） 其核心拥有 avbeta3 整合素异二聚体和 a4 层粘连蛋白 细胞外基质中含有亚基的配体。此外，VMA 特征性地含有我们假设参与的凝集素 介导波形蛋白细胞骨架的细胞表面锚定。这个路口 以生长因子依赖性方式组装，似乎在 EC 中发挥作用 迁移和分支形态发生，血管生成的基本要素， 因为针对 avbeta3 整合素异二聚体和 a4 的抗体 层粘连蛋白亚基抑制这些事件。在目标1中，我们将进一步采取 VMA 分子组成的表征 强调其蛋白质成分如何相互作用以及鉴定 参与细胞内波形蛋白细胞骨架锚定的分子 表面。在目标 2 中，我们将研究生活中 VMA 组装的动态 我们在其中表达了带有绿色荧光标记的 VMA 蛋白的 EC 蛋白质。在目标 3 中，我们将分析 VMA 组件的功能 体内血管生成。这些研究将为我们的作用提供新的见解 血管生成中的整合素/基质相互作用。

DESCRIPTION (provided by the applicant): The lumen of blood vessels is lined by endothelial cells (ECs). The latter lie on a basement membrane whose structural elements include laminins, proteoglycans and collagens. ECs interact with these matrix proteins, in part, via receptors called integrins. Such interactions are involved in regulating a number of cellular functions including adhesion, motility and gene expression. In the adult, endothelial cells in the vessels are quiescent. However, in wound healing and in pathological conditions including cancer and inflammatory diseases, a stimulus activates new vessel growth, a process called angiogenesis. In this application, our studies are focused on a novel matrix junction that we recently identified in ECs. Preliminary experiments indicate that endothelial cells assemble a novel focal contact-like structure that is associated with both the microfilament and vimentin cytoskeletons. This vimentin-associated matrix adhesion (VMA) possesses, at its core, the avbeta3 integrin heterodimer and an a4 laminin subunit-containing ligand in the extracellular matrix. In addition, the VMA characteristically contains plectin that we hypothesize is involved in mediating cell surface anchorage of the vimentin cytoskeleton. This junction assembles in a growth factor-dependent manner and appears to play a role in EC migration and branching morphogenesis, essential elements of angiogenesis, since antibodies against both the avbeta3 integrin heterodimer and the a4 laminin subunit inhibit these events. In aim 1, we will undertake further characterization of the molecular composition of the VMA with particular emphasis on how its protein components interact and on identification of the molecules involved in anchorage of the vimentin cytoskeleton at the cell surface. In aim 2, we will study the dynamics of assembly of the VMA in living ECs in which we have expressed VMA proteins tagged with green fluorescent protein. In aim 3, we will analyze the function(s) of components of the VMA in angiogenesis in vivo. These studies will provide new insight into the role of integrin/matrix interactions in angiogenesis.