MRP-14, CD36 and Thrombosis

 描述（由申请人提供）：血栓性心血管（CV）疾病，包括心脏病发作（MI）、卒中和深静脉血栓形成（DVT），是发达国家的主要死因。利用血小板的转录谱，我们确定了S100钙调节蛋白家族成员MRP-14（S100 A9）作为急性MI基因。病例对照验证研究表明，血浆MRP-8/14复合物水平升高可预测未来CV事件风险增加。使用MRP-14-/-小鼠的研究确定MRP-8/14广泛调节血管炎症。然而，一个关键的未回答的问题是MRP-8/14是否直接参与血栓形成。在最近的一份报告（Wang et al. J Clin Invest 2014）中，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在血小板中表达并由血小板分泌，并且来自MRP-14-/-小鼠的全血中的血栓形成减少。将WT血小板或纯化的MRP-14输注到MRP-14-/-小鼠中缩短了颈动脉闭塞时间，表明血小板衍生的MRP-14直接调节血栓形成。我们接下来鉴定了CD 36作为MRP-14的血小板膜受体。重要的是，虽然MRP-14的缺乏对血栓形成有保护作用，但它对止血的多个参数没有影响。该项目的中心假设是，血小板MRP-14以CD 36依赖性方式调节动脉和静脉血栓形成，这种相互作用可用于开发更安全的抗血栓形成剂（即，降低出血风险），并且血浆MRP- 8/14水平由CV疾病活动性遗传决定和修饰。我们提出三个具体目标。首先，我们将表征负责MRP-14：CD 36结合的分子结构域和导致血小板活化的下游信号传导。其次，我们将研究MRP-14在动脉粥样硬化背景下静脉血栓形成和动脉血栓形成中的作用。第三，血浆MRP-8/14浓度的主要遗传、细胞和CV疾病活动决定因素将与基因和血液凝固研究合作进行探索。MRP-14：CD 36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DVT。这些研究的结果将提供重要的见解，以利用这种相互作用来影响血栓形成，但不影响止血（即，降低出血风险）。

 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).