Regulation of GPIIb-IIIa by the platelet cytoskeleton

描述(申请人逐字描述)：整合素家族成员 受体在诱导黏附中起关键作用，并参与 需要整合素诱导细胞行为改变的大量事件。为 例如，跨整合素的信号参与血管生成、发育、 转移、炎症、伤口愈合和止血。的总目标是 我们的研究是为了了解导致整合素的信号通路 激活和整合素诱导的细胞行为改变。我们的工作重点是 膜骨架蛋白及其相关信号转导的重要性 分子参与调节整合素之间的双向信号传递。研究结束 过去供资期间提供的证据表明，11bB3的亚群 在血小板中与膜骨架复合体有关，包含 血影蛋白、talin、pp60c-src和calain。当血小板或培养细胞扩散时， 这些蛋白质通过一种机制被整合到整合素簇中 需要钙调蛋白的活性。RAC随后被一个机制激活，该机制 可被血影蛋白的SH3结构域抑制。我们的发现与一项 整合素参与导致钙蛋白酶激活的模型。钙调蛋白 切割几种蛋白质，包括血影蛋白和β3整合素亚基， 允许原本受细胞骨架限制的整合素聚集在一起 变成焦点复合体。通过这些复合体传输的信号，由一个 涉及血影蛋白的机制，导致RAC的激活。我们已经确定了 骨架蛋白作为一种新的与Beta3胞浆结构域相互作用的蛋白质 并表明它存在于整合素簇中。在中国的实验 目前的提案旨在测试以下假设： AlIbbeta3与膜骨架蛋白和信号转导的复合体 分子在允许双向信号传递方面起着关键作用。 整合素。具体目的是：1)检验CalPain是 参与RAC的激活；2)检验SH3结构域的假设 血影蛋白参与RAC的激活；3)检验假设 骨架蛋白与整合素胞质结构域相互作用的双向调节 整合素的信号传递。预计这些研究将提供 有关跨INTNG的双向信令涉及的机制的信息。 此外，这些研究可能会增加对关键机制的理解 参与整合素介导的功能，如血小板黏附和 聚集、伤口愈合、血管生成、炎症、转移和细胞 迁移。

DESCRIPTION (Applicant's Description Verbatim): Members of the integrin family of receptors play a critical role in inducing adhesion and are involved in numerous events that require integrin-induccd changes in cell behavior. For example, signaling across integrins is involved in angiogenesis, development, metastasis, inflammation, wound healing, and hemostasis. The overall goal of our research is to understand the signaling pathways leading to integrin activation and to integrin-induced changes in cell behavior. Our work focuses on the importance of membrane skeleton proteins and associated signaling molecules in regulating the two-way signaling across integrins. Studies over the past funding period have provided evidence that a subpopulation of a11bB3 in platelets is associated with membrane skeleton complexes containing spectrin, talin, pp60c-src, and calpain. As platelets or cultured cells spread, these proteins are incorporated into integrin clusters by a mechanism that requires calpain activity. Rac is subsequently activated by a mechanism that can be inhibited by spectrin's SH3 domain. Our findings are consistent with a model in which integrin engagement causes activation of calpain. Calpain cleaves several proteins including spectrin and the beta3 integrin subunit, allowing integrin that is otherwise restrained by the cytoskeleton to cluster into focal complexes. Signaling transmitted across these complexes, by a mechanism involving spectrin, leads to activation of Rac. We have identified skelemin as a new protein that can interact with the beta3 cytoplasmic domain and shown that it is present in the integrin clusters. Experiments in the present proposal are designed to test the hypothesis that association of alIbbeta3 with the complexes of membrane skeleton proteins and signaling molecules plays a critical role in allowing two-way signaling across the integrin. The Specific Aims are 1) to test the hypothesis that calpain is involved in Rac activation; 2) to test the hypothesis that the SH3 domain of spectrin is involved in Rac activation; 3) to test the hypothesis that interaction of skelemin with integrin cytoplasmic domains regulates two-way signaling across integrins. It is anticipated that these studies will provide information on mechanisms involved in two-way signaling across integnns. Further, the studies may lead to an increased understanding of key mechanisms involved in integrin-mediated functions such as platelet adhesion and aggregation, wound healing, angiogenesis, inflammation, metastasis, and cell migration.