Integrins in the Endothelial Response to Fluid Shear Stress

描述(由申请人提供)：血管内皮细胞的基因表达和行为受到流动血液的流体剪应力的高度调控。内皮细胞对血流的反应调节血管胚胎的发生、正常的血管生理和动脉粥样硬化的发展。我们以前的工作发现了一个由PECAM-1、VE-钙粘蛋白和血管内皮生长因子受体2组成的机械转导复合体，它位于细胞-细胞连接处，在这个系统中介导力到生化信号的转换。PECAM-1似乎是真正的力传感器，VE-钙粘蛋白作为适配器将VEGFR2带入复合体，VEGFR酪氨酸激酶启动关键的下游信号。这些信号包括将整合素转换为高亲和力状态，从而导致其与细胞外基质结合。然后，这些新结合的整合素产生信号。与这个模型一致的是，内皮细胞下的细胞外基质对血流诱导的信号进行了关键的调节。特别是，PAK(p21激活的激酶)调节这种基质特异性的关键方面。本项目旨在阐明连接性机械转导复合体转导的分子机制，并测试PAK在体内动脉粥样硬化形成中的作用。为了实现这些总体目标，我们将：1)测量PECAM-1的作用力，并阐明PECAM-1细胞质结构域在机械转导中的作用。2)确定通过VE-钙粘蛋白介导接头功能的蛋白质相互作用。3)检测PAK基因缺陷小鼠的血管炎症和动脉粥样硬化形成。公共卫生相关性：动脉粥样硬化是一种慢性炎症性动脉疾病。在美国，大约一半的死亡是由心脏病发作、中风或其他与动脉粥样硬化相关的血管事件引起的。虽然高脂血症和糖尿病等危险因素是重要的危险因素，但动脉粥样硬化是在易受液体流动干扰的动脉区域启动和维持的。本项目将研究动脉中机械转导导致动脉粥样硬化的分子机制。了解流体剪切力如何引起血管炎症可能会确定新的药物靶点，从而可能导致更有效的治疗方法来预防或治疗这些疾病。

DESCRIPTION (provided by applicant): Endothelial cell gene expression and behavior is highly regulated by fluid shear stress from flowing blood. Endothelial responses to flow regulate vascular embryogenesis, normal vascular physiology and development of atherosclerosis. Our previous work identified a mechanotransduction complex consisting of PECAM-1, VE-cadherin and VEGF receptor 2 that resides at cell-cell junctions and mediates conversion of force to biochemical signals in this system. PECAM-1 appears to be the true force transducer, VE-cadherin functions as an adapter that brings VEGFR2 into the complex and the VEGFR tyrosine kinase initiates key downstream signals. These signals include conversion of integrins to high affinity states, which leads to their binding to extracellular matrix. These newly bound integrins then generate signals. Consistent with this model, the extracellular matrix under the endothelial cells critically modulates the signals induced by flow. In particular, PAK (p21-activated kinase) mediates critical aspects of this matrix specificity. The current project aims to elucidate the molecular mechanism for transduction by the junctional mechanotransduction complex and to test the role of PAK in atherogenesis in vivo. To achieve these overall goals we will: 1) measure forces across PECAM-1 and elucidate the role of the PECAM-1 cytoplasmic domain in mechanotransduction. 2) identify the protein interactions that mediate adapter function by VE-cadherin. 3) examine vascular inflammation and atherogenesis in PAK-deficient mice. PUBLIC HEALTH RELEVANCE: Atherosclerosis is a chronic inflammatory disease of arteries. Approximately half of all deaths in the United States are caused by heart attacks, strokes or other vascular events associated with atherosclerosis. While risk factors such as hyperlipidemia and diabetes are important risk factors, atherosclerosis is initiated and maintained at regions of arteries that are subject to disturbances in fluid flow. This project will investigate the molecular mechanisms of mechanotransduction in arteries that leads to atherosclerosis. Understand how fluid shear stress induces vascular inflammation is likely to identify new drug targets that may lead to more effective therapies to prevent or treat these diseases.