ERO1 alpha in platelet activity and thrombosis

项目摘要 尽管我们对介导血小板血栓形成的机制的理解有所进展，但目前 抗血小板药物会增加大出血的风险。为了确定新的治疗靶点，我们和 其他研究表明，血管内蛋白二硫键异构酶（PDI）对αIIbβ3整合素的完全激活至关重要 和动脉血栓形成中的血小板聚集，提供了对新的抗血栓剂的见解。然而，在这方面， 阻断血管内PDI的氧化还原酶活性可延长小鼠尾出血时间。我们的初步 有数据表明，内质网（ER）氧化还原蛋白1α（Ero 1 α），一种在PDI中起关键作用的氧化酶， ER从活化的血小板中释放，血小板Ero 1 α的抑制或缺失会改变ER的活性。 血小板表面结合的PDI和损害血小板聚集功能。此外，我们还发现，全球 Ero 1 α的缺失减少了血小板血栓形成的大小，而不影响初始血小板粘附， 血管损伤后尾部出血时间。使用新的生物化学、细胞和体内动物研究 药理学抑制剂和Ero 1 α条件性基因敲除和全基因敲除小鼠， 将检验血小板释放的Ero 1 α调节细胞上PDI和αIIbβ3整合素功能的假设 并有助于血小板血栓形成的传播步骤，而不影响止血 血管损伤后。在目标1中，我们将确定细胞外Ero 1 α 促进血小板聚集。在目标2中，我们将测试动脉血栓形成条件是否改变 胞外Ero 1 α在目标3中，我们将确定血管内和血小板源性的 Ero 1 α在血栓形成条件下血小板粘附和聚集以及血管闭塞中的作用拟议 研究将确定血小板血栓形成的中心调节机制， 安全有效治疗血栓性疾病的新治疗策略。

Project Summary Despite advances in our understanding of the mechanisms mediating platelet thrombus formation, current antiplatelet drugs increase the risk of major bleeding. In an effort to identify novel therapeutic targets, we and others showed that intravascular protein disulfide isomerase (PDI) is crucial for full activation of αIIbβ3 integrin and platelet accumulation in arterial thrombosis, providing insights into a new antithrombotic agent. However, blocking the oxidoreductase activity of intravascular PDI prolongs tail bleeding times in mice. Our preliminary data have demonstrated that endoplasmic reticulum (ER) oxidoreductin 1α (Ero1α), a key oxidase of PDI in the ER, is released from activated platelets and that inhibition or deletion of platelet Ero1α alters the activity of platelet surface-bound PDI and impairs platelet aggregatory function. Furthermore, we have found that global deletion of Ero1α reduces the size of platelet thrombus formation without affecting initial platelet adhesion and tail bleeding times following vascular injury. Using biochemical, cellular and in vivo animal studies with novel pharmacological inhibitors and Ero1α conditional knockout and global knockout mice developed by our lab, we will test the hypothesis that platelet-released Ero1α regulates the function of PDI and αIIbβ3 integrin on the cell surface and contributes to the propagation step of platelet thrombus formation without affecting hemostasis following vascular injury. In Aim 1, we will identify the molecular mechanism by which extracellular Ero1α promotes platelet aggregation. In Aim 2, we will test whether arterial thrombotic conditions alter the function of extracellular Ero1α. In Aim 3, we will determine the pathophysiological role of intravascular and platelet-derived Ero1α in platelet adhesion and accumulation and vessel occlusion under thrombotic conditions. The proposed studies will identify a central regulatory mechanism of platelet thrombus formation and lead to the discovery of novel therapeutic strategies for the safe and effective treatment of thrombotic disease.