INTEGRIN/CYTOSKELETON INTERACTIONS IN PLATELETS

血小板在血凝块的形成中起关键作用。这是 正常止血中的重要生理事件，但 血液凝块的病理发展可导致心脏病发作， 中风在血凝块形成的过程中，血小板被激活， 并迅速组装肌动蛋白细胞骨架。这些都与 主要跨膜整合素α IIb/β 3，介导粘附至 血小板表面的纤维蛋白α IIb/β 3与 细胞骨架允许血小板收缩形成凝块。第一个目标是 格兰特的任务是确定α IIb/β 3的胞质结构域 与特定的细胞骨架成分相互作用。将采取若干战略， 用于鉴定与α IIb/β 3相关的细胞骨架蛋白 in vivo.在细胞质中突变的α IIb/β 3的相互作用 结构域将被调查，将整合素的相互作用 嵌合体，其中胞质结构域连接到 其他蛋白质的跨膜和胞外结构域。一种方案 建议允许分析细胞骨架与个体的联系， 其他蛋白质的胞质结构域。提出了一项计划， 分析细胞骨架与单个胞质结构域的连接 嵌合体以及已被诱导二聚化的嵌合体。的作用 特定的蛋白质，如talin、黏着斑蛋白和α-辅肌动蛋白，将被 在已经删除黏着斑蛋白的细胞中探索， 或者α辅肌动蛋白的功能被破坏了。许多代理人， 防止血小板活化，提高环核苷酸水平， 蛋白激酶A或G。这些激酶的一个重要底物， 血管扩张刺激磷蛋白（VASP）中的血小板。我们将 探讨VASP的功能及其磷酸化在 与肌动蛋白聚合和激活 α IIb/β 3。响应于血小板活化和聚集， 几种酪氨酸激酶被激活。我们将调查 酪氨酸磷酸酶对血小板酪氨酸磷酸化的调节 （PTPs）。具体来说，我们将寻找与以下方面有关的PTP， 调节酪氨酸激酶和与α IIb/β 3相关的PTP。

Platelets play a critical role in the development of blood clots. This is an important physiological event in normal hemostasis, but the pathological development of blood clots can lead to heart attacks and strokes. During the formation of a blood clot, platelets become activated and rapidly assemble their actin cytoskeletons. These become linked to the major transmembrane integrin alphaIIb/beta3, which mediates adhesion to fibrin on the outside of the platelet. The coupling of alphaIIb/beta3 to the cytoskeleton allows platelets to contract clots. The first aim of this grant is to determine how the cytoplasmic domains of alphaIIb/beta3 interact with specific cytoskeletal components. Several strategies will be used to identify cytoskeletal proteins that associate with alphaIIb/beta3 in vivo. The interactions of alphaIIb/beta3 mutated in the cytoplasmic domains will be investigated, as will the interactions of integrin chimeras, in which the cytoplasmic domains are ligated onto the transmembrane and extracellular domains of other proteins. A scheme is proposed to permit analysis of the cytoskeletal links to individual cytoplasmic domains of other proteins. A scheme is proposed to permit analysis of the cytoskeletal links to individual cytoplasmic domain chimeras as well to chimeras to have been induced to dimerize. The role of specific proteins, such as talin, vinculin and alpha-actinin, will be explored in cells from which vinculin has been deleted and in which talin or alpha-actinin have been functionally disrupted. Many agents which prevent platelet activation raise cyclic nucleotide levels and stimulate protein kinase A or G. A prominent substrate for these kinases in platelets in the vasodilator-stimulated phosphoprotein (VASP). We will explore the function of VASP and the consequence of its phosphorylation in relation both to actin polymerization and the activation of alphaIIb/beta3. In response to platelet activation and aggregation, several tyrosine kinases become activated. We will investigate the regulation of platelet tyrosine phosphorylation by tyrosine phosphatases (PTPs). Specifically, we will look for PTPs that associate with and regulate tyrosine kinases, and PTPs that associate with alphaIIb/beta3.