12-lipoxygenase regulation of FcgRIIa-mediated platelet activation

描述（由申请人提供）：心血管疾病（CVD）是美国每年的主要死亡原因，占美国死亡人数的近三分之一，每年的医疗保健费用超过5000亿美元。血小板介导的血栓形成是导致危及生命的心血管临床事件（如卒中或心肌梗死）的主要潜在机制。血小板介导的血栓形成的一种形式是通过免疫复合物激活FcγRIIa（一种在胞质尾区含有ITAM的跨膜受体）。FcγRIIa的活化导致免疫介导的血小板减少症和血栓形成，这通常会导致接受肝素或发生脓毒症的患者发生危及生命的心血管相关并发症。已证明血小板12-脂氧合酶（12-LOX）是Fcγ RIIa介导的血小板活化的重要调节剂;然而，12-LOX调节FcγRIIa信号传导的潜在信号传导机制仍不清楚。了解12-LOX调节该途径的信号传导机制是验证其作为预防免疫介导的血栓形成事件的潜在和有效的抗血小板靶点的作用的关键步骤。对于这个提议，我将致力于1）阐明12-LOX调节Fcγ RIIa介导的血小板活化的潜在机制。将研究和鉴定12-羟基二十碳四烯酸（12-HETE）（主要的12-LOX氧化脂质）和12-LOX的潜在蛋白结合伴侣在FcγRIIa信号通路中的作用。这些研究将为12-LOX在Fcγ RIIa介导的血小板活化途径中的生物化学作用提供有价值和更深入的见解。目的将2）通过利用表达人源化FcγRIIa且与正常12-LOX模型（hFcR/ALOX 12 +/+）相比缺乏12-LOX的转基因小鼠（hFcR/ALOX 12-/-）来表征12-LOX在体内的作用。体内方法将有助于确定12-LOX是否被证明是治疗和限制免疫介导的血小板减少症以及预防血栓形成的有效靶点。阐明12- LOX及其氧脂肽调节Fcγ RIIa介导的血小板功能的潜在机制对于加速涉及血栓闭塞发生率的免疫介导疾病的新型治疗方法的合理设计至关重要。

DESCRIPTION (provided by applicant): Cardiovascular disease (CVD) is the leading cause of death in the US annually, accounting for nearly 1 in 3 deaths and over $500 billion in annual health care cost in the US. Platelet-mediated thrombosis is the primary underlying mechanism leading to cardiovascular life-threatening clinical events, such as stroke or myocardial infarction One form of platelet-mediated thrombosis is through the immune-complex activation of FcγRIIa (a transmembrane receptor containing ITAM in the cytoplasmic tail). The activation of FcγRIIa is responsible for immune-mediated thrombocytopenia and thrombosis, which can often lead to life-threatening cardiovascular related complications in patients who receive heparin or experience sepsis. Platelet 12-lipoxygenase (12-LOX) has been demonstrated to be an essential modulator of FcγRIIa-mediated platelet activation; however, the underlying signaling mechanism by which 12-LOX regulates the FcγRIIa signaling is still unclear. Understanding the signaling mechanisms by which 12-LOX regulates this pathway is a critical step in validating its role as a potential and effective anti-platelet target for the prevention of immune-mediated thrombotic events. For this proposal, I will aim to 1) elucidate the underlying mechanisms by which 12-LOX regulates the FcγRIIa-mediated activation in platelets. The role of 12-hydroxyeicosatetraenoic acid (12-HETE), the predominant 12-LOX oxidized lipid, and potential protein binding partners of 12-LOX will be investigated and identified in the FcγRIIa signaling pathway. These studies will provide valuable and deeper insights in the biochemical roles of 12-LOX in the FcγRIIa-mediated platelet activation pathway. Aim will 2) Characterize the role of 12-LOX in vivo by utilizing transgenic mice expressing humanized FcγRIIa and deficient in 12-LOX (hFcR/ALOX12-/-) compared to the normal 12-LOX model (hFcR/ALOX12+/+). The in vivo approaches will aid in determining whether 12-LOX proves to be an efficient target in treating and limiting immune-mediated thrombocytopenia and as well preventing thrombosis. Elucidating the underlying mechanisms by which 12- LOX and its oxylipin regulate FcγRIIa-mediated platelet function is crucial in order to accelerate the rational design of novel therapeutics for immune-mediated disorders involving incidence of thrombotic occlusion.