Integrin Signaling in Hemostasis and Blood Diseases

描述(由申请人提供)： 细胞-细胞外基质的相互作用受到激活整合素的“内向外”信号的严格调控。 整合素连接和聚集定位并激活细胞黏附部位的蛋白质，启动“由外而内” 调节生物反应的信号。在血液和血管细胞中，这种双向信号最明显，在血液和血管细胞中，整合素控制着生长、分化、存活和功能。该计划项目的目的是描述血液和血管细胞中整合素信号的基本机制。个别项目将检查血小板、内皮细胞和平滑肌细胞，但共同的目标是确定整合素信号的一般规则。项目1将检验这一假设，即血小板中由外向内的信号是由整合素、Src家族激酶和Src调节蛋白之间的动态和直接相互作用触发的。这一过程的分子机制将被确定，破坏这些相互作用对血栓形成的后果将在基因靶标小鼠中确定。项目2描述了ERK 1/2、Rap1、R-RAS和PEA-15在整合素激活中的作用。它现在将检验这一假设，即Rap1和R-RAS的特定效应器在一定程度上通过与talin的相互作用来调节这一过程。由于PEA-15在血管细胞中表达，其在血管修复和血管生成中的作用将被确定。项目3将描述整合素结扎如何在缺血性疾病中影响血管内皮生长因子诱导的内皮细胞屏障破坏，以及在血管渗漏过程中暴露的基底膜蛋白如何招募血小板形成有害的微血栓。它还将表征信号素-3A如何在缺乏血管内皮生长因子的情况下促进血管渗漏和抑制血管生成。项目4将研究Abl酪氨酸激酶和整合素信号之间的关系。它将检验以下假设：Beta3整合素通过依赖于Src的p62Dok-1酪氨酸磷酸化激活Abl，以及Abl磷酸化Src底物以抑制细胞扩散。Abl和已知的F-肌动蛋白调节因子之间的关系将通过使用shRNA文库筛选识别调节Abl功能的基因来确定。这些项目将得到提供重组蛋白质、细胞成像能力和行政协调的核心单位的支持。该计划实现的协同作用将加深我们对整合素信号的理解，并对影响止血和血管修复的细胞黏附障碍产生影响。

DESCRIPTION (provided by applicant): Cell-extracellular matrix interactions are tightly regulated by "inside-out" signals that activate integrins. Integrin ligation and clustering localize and activate proteins at cell adhesion sites to initiate "outside-in" signals that mediate biological responses. No where is this bidirectional signaling more apparent than in blood and vascular cells, where integrins control growth, differentiation, survival and function. The purpose of this Program Project is to characterize fundamental mechanisms of integrin signaling in blood and vascular cells. Individual projects will examine platelets, endothelial cells and smooth muscle cells, but the common goal is to identify general rules of integrin signaling. Project 1 will test the hypothesis that outside-in signaling in platelets is triggered by dynamic and direct interactions between integrins, Src family kinases and Src regulatory proteins. Molecular mechanisms of this process will be characterized, and consequences of disrupting these interactions on thrombus formation will be determined in gene-targeted mice. Project 2 has characterized the roles of ERK 1/2, Rap1, R-Ras and PEA-15 in integrin activation. It will now test the hypothesis that specific effectors of Rap1 and R-Ras mediate this process, in part through interactions with talin. Since PEA-15 is expressed in vascular cells, its roles in vessel repair and angiogenesis will be determined. Project 3 will characterize how integrin ligation influences endothelial cell barrier disruption induced by VEGF during ischemic disease and how basement membrane proteins exposed during vascular leak recruit platelets to form deleterious micro-thrombi. It will also characterize how semaphorin-3A promotes vascular leak in the absence of VEGF and inhibits angiogenesis. Project 4 will examine relationships between the Abl tyrosine kinase and integrin signaling. It will test the hypotheses that beta3 integrin activates Abl through Src-dependent tyrosine phosphorylation of p62Dok-1, and that Abl phosphorylates Src-substrates to inhibit cell spreading. The relationships between Abl and known regulators of F-actin will be determined by identification of genes that modulate Abl function using an shRNA library screen. These projects will be supported by core units that provide recombinant proteins, cell imaging capabilities and administrative coordination. The synergy achieved by this Program will further our understanding of integrin signaling, with implications for disorders of cell adhesion affecting hemostasis and vascular repair.