COLLAGEN RECEPTOR SIGNALING IN PLATELETS

血小板中的胶原蛋白受体信号传导

• 批准号: 6931307
• 负责人: Leslie V. Parise
• 金额: $ 20.52万
• 依托单位: UNIV OF NORTH CAROLINA CHAPEL HILL
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-01-01 至 2008-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6931307
• 关键词: binding proteins; biological signal transduction; collagen; complementary DNA; flow cytometry; genetically modified animals; guanine nucleotide binding protein; guanosinetriphosphatases; integrins; laboratory mouse; megakaryocytes; northern blottings; phosphorylation; platelet activation; protein kinase; protein protein interaction; protein sequence; protein structure function; receptor expression; recombinant proteins; two dimensional gel electrophoresis; western blottings; yeast two hybrid system

Platelets become exposed to collagen during rupture of the atherosclerotic plaque and during normal vascular injury. The exposed collagen serves not only as a direct platelet agonist but also provides an adhesive surface to platelets, thus contributing to thrombosis. Two of the major collagen receptors on platelets are glycoprotein (GP) VI and the Alpha-2 Beta-1 integrin. GPVI and Alpha-2 Beta-1 are both required for full collagen mediated platelet adhesion and activation, likely involving a GPVI-mediated activation of Alpha?2 Beta-1 as demonstrated by our lab and others. However, signals leading to Alpha-2 Beta-1 activation by GPVI or other agonist receptors are not well understood. Related to this, the small GTPases Rap1 and R-Ras have each been proposed as positive regulators of integrin activation whereas Ras has been proposed as a negative regulator. We recently demonstrated that GPVI signaling in platelets leads to Rap1 activation in a manner dependent upon secreted ADP activation of the P2Y12 receptor as well as a P2Y12-independent pathway. We also provide preliminary evidence using a transducible primary mouse megakaryocyte system, that Rap1 may promote Alpha-2 Beta-1 activation. In separate studies we found that R-Ras promotes several Alpha-2 Beta-1 mediated events, and that Ras is present in platelets and activated by agonist stimulation. However, the interrelationship of Rap1 to R-Ras or Ras is not understood. In the present proposal, we aim to further define the communication between GPVI and Alpha-2 Beta-1 by first, clarifying the roles of Rap1 and R-Ras in GPVI-induced Alpha-2 Beta-1 activation, second, mapping upstream pathways leading to Rap1 activation with regard to the potential role of R-Ras and other molecules in this event, third, mapping signaling pathways downstream of activated Rap1 leading to Alpha-2 Beta-1 integrin activation, and finally, determining the role of Ras in regulating Alpha-2 Beta-1 integrin activation. Results from these studies will provide fundamental information on how these important collagen receptors communicate with one another via these small G-proteins in platelets and megakaryocytes.

在动脉粥样硬化斑块破裂和正常血管损伤期间，血小板暴露于胶原蛋白。暴露的胶原蛋白不仅作为直接的血小板激动剂，而且还为血小板提供粘附表面，从而促进血栓形成。血小板上的两种主要胶原受体是糖蛋白（GP）VI和α-2 β-1整联蛋白。GPVI和α-2 β-1都需要完全胶原介导的血小板粘附和活化，可能涉及GPVI介导的α？2 Beta-1，正如我们实验室和其他人所证明的那样。然而，导致GPVI或其他激动剂受体激活α-2 β-1的信号还不清楚。与此相关，小GTP酶Rap 1和R-Ras各自被认为是整合素活化的正调节剂，而Ras被认为是负调节剂。我们最近证实，血小板中的GPVI信号传导以依赖于P2 Y12受体的分泌型ADP活化以及P2 Y12非依赖性途径的方式导致Rap 1活化。我们还提供了初步的证据，使用可转导的原代小鼠巨核细胞系统，Rap 1可能促进α-2 Beta-1激活。在单独的研究中，我们发现R-Ras促进几种α-2 β-1介导的事件，并且Ras存在于血小板中并通过激动剂刺激激活。然而，Rap 1与R-Ras或Ras的相互关系尚不清楚。在本提案中，我们的目标是进一步定义GPVI和Alpha-2 Beta-1之间的通信，首先，澄清Rap 1和R-Ras在GPVI诱导的Alpha-2 Beta-1激活中的作用，其次，绘制导致Rap 1激活的上游途径，考虑R-Ras和其他分子在该事件中的潜在作用，第三，绘制活化Rap 1下游导致α-2 β-1整联蛋白活化的信号通路，并最终确定Ras在调节α-2 β-1整联蛋白活化中的作用。这些研究的结果将提供有关这些重要的胶原蛋白受体如何通过血小板和巨核细胞中的这些小G蛋白相互通讯的基本信息。