MRP-14, CD36 and Thrombosis

 描述(申请人提供)：血栓性心血管(CV)疾病，包括心脏病发作(MI)、中风和深静脉血栓形成(DVT)，是发达国家的主要死亡原因。利用血小板转录图谱，我们鉴定了S100钙调节蛋白家族成员MRP-14(S100A9)为急性心肌梗死基因。病例对照验证研究表明，血浆MRP-8/14复合体水平升高预示着未来心血管事件风险的增加。使用MRP-14-/-小鼠的研究确定，MRP-8/14广泛调节血管炎症。然而，一个关键的悬而未决的问题是MRP-8/14是否直接参与血栓形成。在最近的一份报告中(Wang等人J Clin Invest 2014)，我们发现MRP-14-/-小鼠的动脉血栓闭塞时间显著延长。我们观察到MRP-14和MRP-8/14在血小板中表达和分泌，并且MRP-14-/-小鼠全血中血栓的形成减少。将WT血小板或纯化的MRP-14注入MRP-14-/-小鼠可缩短颈动脉阻断时间，表明血小板来源的MRP-14直接调节血栓形成。接下来，我们确定CD36是MRP-14的血小板膜受体。重要的是，虽然MRP-14缺乏对血栓形成有保护作用，但对止血的多项参数没有影响。该项目的中心假设是，血小板MRP-14以CD36依赖的方式调节动脉和静脉血栓形成，这种相互作用可以被用来开发更安全的抗血栓药物(即减少出血风险)，以及血浆MRP-8/14水平是由心血管疾病活动遗传决定和改变的。我们提出了三个具体目标。首先，我们将描述负责MRP-14：CD36结合的分子结构域以及导致血小板激活的下游信号。其次，我们将在动脉粥样硬化的背景下，研究MRP-14在静脉血栓形成和动脉血栓形成中的作用。第三，将与基因和凝血研究合作，探索血浆MRP-8/14浓度的主要遗传、细胞和心血管疾病活动决定因素。MRP-14：CD36的相互作用代表了治疗心血管疾病的新靶点，包括心脏病发作、中风和深静脉血栓。这些研究的结果将为利用这种相互作用影响血栓形成而不是止血(即降低出血风险)提供重要的见解。

 DESCRIPTION (provided by applicant): Thrombotic cardiovascular (CV) diseases, including heart attack (MI), stroke and deep venous thrombosis (DVT), are the leading cause of death in developed countries. Using transcriptional profiling of platelets, we identified the S100 calcium-modulated protein family member MRP-14 (S100A9) as an acute MI gene. Case- control validation studies demonstrated that elevated plasma levels of MRP-8/14 complexes predict increased risk of future CV events. Studies using MRP-14-/- mice determined that MRP-8/14 broadly regulates vascular inflammation. However, a key unanswered question is whether MRP-8/14 participates directly in thrombosis. In a recent report (Wang et al. J Clin Invest 2014), we showed that the time to arterial thrombotic occlusion was prolonged markedly in MRP-14-/- mice. We observed that MRP-14 and MRP-8/14 are expressed in and secreted by platelets, and that thrombus formation is reduced in whole blood from MRP-14-/- mice. Infusion of WT platelets or purified MRP-14 into MRP-14-/- mice shortened the carotid artery occlusion time, indicating that platelet-derived MRP-14 directly regulates thrombosis. We next identified CD36 as the platelet membrane receptor for MRP-14. Importantly, while deficiency of MRP-14 is protective of thrombosis, it has no effect on multiple parameters of hemostasis. The central hypotheses of this project are that platelet MRP-14 regulates arterial and venous thrombosis in a CD36-dependent manner, that this interaction can be exploited to develop a safer anti-thrombotic agent (i.e., reduced bleeding risk), and that plasma MRP- 8/14 levels are genetically determined and modified by CV disease activity. We propose 3 specific aims. First, we will characterize the molecular domains responsible for MRP-14:CD36 binding and the downstream signaling that leads to platelet activation. Second, we will investigate the role of MRP-14 in venous thrombosis and in arterial thrombosis in the context of atherosclerosis. Third, major genetic, cellular, and CV disease activity determinants of plasma MRP-8/14 concentration will be explored in collaboration with the Genes and Blood Clotting Study. The MRP-14:CD36 interaction represents a novel target for treating cardiovascular disorders, including heart attack stroke, and DVT. The results of these studies will provide important insights to exploit this interaction to influence thrombosis, but not hemostasis (i.e., reduced bleeding risk).