Genetic regulation of racial differences in platelet reactivity

描述(申请人提供)：冠心病(CHD)是白人和黑人最常见的杀手。然而，与白人相比，黑人的冠心病发病率增加了2倍，长期存活率也更低。这些差异不能用人口统计学、临床或经济混杂因素来完全解释。由于心肌梗死和中风通常是由动脉粥样硬化斑块破裂部位形成的闭塞血小板血栓引起的，了解黑人和白人血小板激活机制的差异有望有助于我们以最佳方式治疗心肌梗死(MI)和中风后的这些人群。我们的初步数据首次表明，1)PAR4介导的血小板聚集的种族差异，以及2)黑人和白人之间差异表达(DE)并调节PRA4激活的血小板mRNAs和microRNAs。这项应用的目标是1)表征导致这些血小板功能种族差异的关键途径和蛋白质，以及2)基因表达差异的分子遗传学基础。这些目标将通过人类血小板和巨核细胞的生理学、生化、基因组和细胞生物学方法来解决。目的1将使用生理和生化终点分析血小板功能的种族差异，以评估PAR4的激活动力学和绝对活性水平。通过整合目标1中获得的信息，目标2将评估在黑人和白人之间表达的新的候选血小板基因DE。这些基因的特点是它们在调节PAR4介导的血小板反应性的种族差异方面具有潜在的作用。特别是，我们发现，在黑人血小板中，磷脂酰胆碱转移蛋白(PC-TP)明显较高 与白人的血小板相比。PC-TP调节细胞内的脂质运动，这是血小板激活的关键过程。其他几个强有力的候选血小板基因-也是种族DE-也将 被刻画出来。目标3将侧重于解释血小板聚集的种族差异的基因表达的新机制。我们已经确定了第一个通过RACE和PAR4介导的血小板聚集而被DE的miRNAs的例子。我们将对培养的人巨核细胞中的候选miRNAs进行基因操作，以评估它们对调节PAR4介导的血小板/巨核细胞反应性的影响。我们还将评估miRNAs差异表达的分子基础。这项研究将首次在信号、蛋白质和遗传水平上表征血小板激活的种族差异。了解血小板活性的种族差异将填补我们在理解为什么BAC在心肌梗塞和中风后比白人遭受更高的发病率和死亡率方面的重大空白。

DESCRIPTION (provided by applicant): Coronary heart disease (CHD) is the most common killer in both whites and blacks. However, blacks have a 2- fold increase in the incidence of CHD as well as a lower long-term survival compared to whites. These differences cannot be fully explained by demographic, clinical, or economic confounders between these groups. As myocardial infarction and stroke typically result from an occlusive platelet thrombus formed at the site of a ruptured atherosclerotic plaque, understanding differences in the mechanisms by which platelets are activated in blacks and whites is expected to aid in our ability to optimally treat these populations following myocardial infarction (MI) and stroke. Our preliminary data demonstrates, for the first time, 1) racial differences in PAR4-mediated platelet aggregation, and 2) platelet mRNAs and microRNAs that are differentially expressed (DE) between blacks and whites and regulate PRA4 activation. The goals of this application are to characterize 1) the critical pathways and proteins responsible for these racial differences in platelet function, and 2 the molecular genetic basis for differences in gene expression. These goals will be addressed with physiology, biochemistry, genomic and cell biology approaches in human platelets and megakaryocytes. Aim 1 will dissect racial differences in platelet function using physiological and biochemical endpoints to assess PAR4 activation kinetics and absolute level of activity. By integrating the information attained in Aim 1, Aim 2 will evaluate novel candidate platelet genes DE expressed between blacks and whites. These genes will be characterized for their potential role in regulating the racial difference in PAR4-mediated reactivity of platelets. In particular, w find phosphatidylcholine transfer protein (PC-TP), is significantly higher in platelets from blacks compared to platelets from whites. PC-TP regulates lipid movement in the cell, a critical process in platelet activation. Several other strong candidate platelet genes - also DE by race - will also be characterized. Aim 3 will focus on novel mechanisms of gene expression that account for racial differences in platelet aggregation. We have identified the first example of miRNAs that are DE by race and by PAR4-mediated platelet aggregation. We will genetically manipulate candidate miRNAs in cultured human megakaryocytes to assess their effects on regulating PAR4-mediated platelet/megakaryocyte reactivity. We will also assess the molecular basis for the differential expression of miRNAs. This study will be the first to characterize racial differences in platelet activation at the signaling, protein and genetic levels. Understanding the racial difference in platelet activity will fill a significant gap in our understanding of why blacs suffer a higher morbidity and mortality than whites following MI and stroke.