Function of a Novel Matrix Junction in Endothelial Cells

描述（由申请人提供）：血管内腔由 内皮细胞（EC）。后者位于基底膜上， 元件包括层粘连蛋白、蛋白聚糖和胶原。EC与这些 基质蛋白质，部分通过一种叫做整合素的受体。此类交互有 参与调节包括粘附在内的多种细胞功能， 运动和基因表达。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， 包括癌症和炎性疾病，刺激物激活新血管 生长，这个过程叫做血管生成。在这个应用程序中，我们的研究是 集中在一个新的矩阵连接，我们最近发现在EC。 初步实验表明，内皮细胞组装一个新的焦点， 接触样结构，其与微丝和 波形蛋白细胞骨架。波形蛋白相关基质粘附（VMA） 在其核心具有α v β 3整联蛋白异源二聚体和α 4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了 介导波形蛋白细胞骨架的细胞表面锚定。这个路口 以生长因子依赖的方式组装，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， 由于抗α v β 3整联蛋白异二聚体和α 4 层粘连蛋白亚基抑制这些事件。在目标1中，我们将进一步 VMA的分子组成的表征， 强调其蛋白质组分如何相互作用，并确定 参与波形蛋白细胞骨架在细胞上锚定的分子 面在目标2中，我们将研究VMA在活体中的组装动力学 我们表达了带有绿色荧光标记的VMA蛋白的EC 蛋白在目标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.