Molecular Mechanisms of Platelet Activation and Adhesion

血小板激活和粘附的分子机制

• 批准号: 7140692
• 负责人: Peter J Newman
• 金额: $ 47.2万
• 依托单位: VERSITI WISCONSIN, INC.
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-12-01 至 2010-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7140692
• 关键词: NOD mouse; SCID mouse; biological signal transduction; blood transfusion; cell adhesion molecules; cellular pathology; clinical research; confocal scanning microscopy; disease /disorder model; enzyme activity; fluorescence microscopy; fluorescence resonance energy transfer; genetic polymorphism; genetically modified animals; human subject; integrins; membrane proteins; model design /development; molecular biology; molecular pathology; phosphorylation; platelet activation; protein tyrosine kinase; protein tyrosine phosphatase; receptor expression; thrombocytopenic purpura

The human platelet plasma membrane contains several hundred different proteins that control crucial functions, including adhesion to extracellular matrix, signal transduction, platelet aggregation, and clot retraction. Central to the ability of platelets to adhere to each other and to extracellular matrix is an abundant supply of cell surface adhesion molecules, including members of the integrin family, that exist in varying states of activation. These cell adhesion receptors, in turn, transmit signals into, and respond to signals from, the cell interior. The molecular details of the signaling pathways that regulate platelet activation and adhesion, however, remain incompletely understood. The goal of this project, therefore, is to examine four interrelated aspects of the molecular mechanisms underlying platelet activation and adhesion. Specific Aim 1 seeks to understand the molecular mechanism by which antibodies to platelet membrane glycoprotein (GP) VI result in the surgical removal of this important adhesion and signaling complex from the platelet surface, rendering platelets unresponsive to the extracellular matrix component, collagen, and less likely to participate in thrombus formation. It is hoped that these studies may enable rational design of future GPVI-specific therapeutics for the treatment of myocardial infarction and stroke. Specific Aim 2 proposes to test a recently-proposed and attractive hypothesis that specific amino acids within the membrane proximal beta-terminal domain of the integrin beta3 subunit control access of macromolecular ligands like fibrinogen and von Willebrand factor to ligand contact sites within the integrin head domain. These studies should provide important insights into how subtle allosteric changes within the extracellular domain might enable transformation of integrins from a low- to high-affinity state. Specific Aim 3 proposes to explore the hypothesis that PECAM-1 functions as an inhibitory receptor by sequestering the protein-tyrosine phosphatase, SHP-2, away from proteins that regulate the activation of Src family kinases. These studies will shed important new light on the mechanism by which PECAM-1, and perhaps other SHP-2 binding proteins, function to modulate cellular activation. Finally, Specific Aim 4 is a hypothesis-generating, translational research aim that seeks to determine whether PECAM-1 expression varies in the human population, and whether variable PECAM-1 expression might predispose individuals to arterial thrombosis or hemorrhage. These studies have the potential to add PECAM-1 to the growing list of cell adhesion and signaling receptors whose expression is linked to bleeding and clotting disorders in humans, and may thereby improve our ability to diagnose, treat, and prevent clinical thrombosis in humans. Together, these studies represent a coordinated line of investigation designed to advance our understanding of platelet physiology and lead to improvements in transfusion therapy, platelet storage, and management of platelet functional and immunological disorders.

人类血小板质膜含有数百种控制关键功能的不同蛋白质， 包括细胞外基质粘附、信号转导、血小板聚集和凝块收缩。中央至 血小板相互粘附以及与细胞外基质粘附的能力是细胞表面的丰富供应 粘附分子，包括整合素家族的成员，以不同的激活状态存在。这些细胞 粘附受体反过来将信号传输到细胞内部并响应来自细胞内部的信号。分子 然而，调节血小板活化和粘附的信号通路的细节仍然不完整 明白了。因此，该项目的目标是检查分子机制的四个相互关联的方面 潜在的血小板活化和粘附。具体目标 1 旨在通过以下方式了解分子机制： 哪些抗血小板膜糖蛋白 (GP) VI 抗体可导致手术切除这一重要的血小板 血小板表面的粘附和信号复合物，使血小板对细胞外信号无反应 基质成分为胶原蛋白，较少参与血栓形成。希望这些研究能够 能够合理设计未来用于治疗心肌梗死和中风的 GPVI 特异性疗法。 具体目标 2 提议测试最近提出的一个有吸引力的假设，即 整合素β3亚基的膜近端β末端结构域控制大分子配体的进入，例如 纤维蛋白原和冯维勒布兰德因子与整合素头域内的配体接触位点。这些研究应该 提供关于细胞外域内微妙的变构变化如何可能实现的重要见解 整合素从低亲和力状态转变为高亲和力状态。具体目标 3 提出探索假设 PECAM-1 通过隔离蛋白质酪氨酸磷酸酶 SHP-2 发挥抑制性受体的作用 来自调节 Src 家族激酶激活的蛋白质。这些研究将为我们提供重要的新线索 PECAM-1 以及其他 SHP-2 结合蛋白调节细胞的机制 激活。最后，具体目标 4 是一个假设生成、转化研究目标，旨在确定 PECAM-1 表达在人群中是否存在差异，以及不同的 PECAM-1 表达是否可能会影响 使个体容易发生动脉血栓或出血。这些研究有可能将 PECAM-1 添加到 越来越多的细胞粘附和信号传导受体，其表达与出血和凝血有关 人类疾病，从而可能提高我们诊断、治疗和预防临床血栓形成的能力 人类。总之，这些研究代表了一系列协调一致的调查，旨在推进我们的研究 了解血小板生理学并改善输血治疗、血小板储存和 血小板功能和免疫疾病的管理。