Regulation of GPIIb-IIIa by the platelet cytoskeleton

描述（申请人逐字描述）：整联蛋白家族成员 受体在诱导粘附中起关键作用，并参与 许多事件需要整合素诱导的细胞行为变化。为 例如，跨整联蛋白的信号传导涉及血管生成，发育， 转移、炎症、伤口愈合和止血。的总目标 我们的研究是了解整合素的信号通路 活化和整合素诱导的细胞行为变化。我们的工作重点 膜骨架蛋白和相关信号的重要性 分子调节整合素之间的双向信号传导。来的研究 过去的资助期提供的证据表明，a11 bB 3的亚群 血小板中的蛋白质与含有以下物质的膜骨架复合物有关 血影蛋白、talin、pp 60 c-src和钙蛋白酶。随着血小板或培养细胞的扩散， 这些蛋白质通过一种机制掺入整联蛋白簇中， 需要钙蛋白酶活性。RAC随后被一种机制激活， 可以被血影蛋白的SH 3结构域抑制。我们的研究结果与 整合素参与导致钙蛋白酶激活的模型。Calpain 切割包括血影蛋白和β 3整联蛋白亚基在内的几种蛋白质， 使原本受细胞骨架限制的整联蛋白聚集 变成焦点复合体信号通过这些复合体传输， 涉及血影蛋白的机制，导致Rac的激活。我们已经确定 一种能与β 3胞质结构域相互作用的新蛋白--白蛋白 并显示它存在于整联蛋白簇中。的实验 目前的建议是为了测试假设，协会的 alIb β 3与膜骨架蛋白和信号传导的复合物 分子在允许双向信号传导中起着关键作用。 整联蛋白具体目的是：1）检验钙蛋白酶是 参与Rac激活; 2）测试的SH 3结构域的假设 血影蛋白参与Rac激活; 3）为了检验以下假设， β-半乳糖苷酶与整合素胞质结构域相互作用调节双向 整合素之间的信号传导。预计这些研究将提供 关于整合子间双向信号传导机制的信息。 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，如血小板粘附， 聚集、伤口愈合、血管生成、炎症、转移和细胞增殖。 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.