Aberrant Platelet Mechanisms in Inherited Human Platelet Function Disorders

描述（由申请人提供）：尽管我们对血小板生理学的理解取得了巨大进展，但绝大多数遗传性血小板功能缺陷患者的潜在分子机制仍然未知。机制，如膜糖蛋白缺陷和储存池缺陷，通常被认为是，但发生在一小部分患者。大多数患者的特征是出血性疾病，血小板激活时聚集和致密颗粒分泌受损，目前被归为“血小板分泌/激活缺陷”的松散定义组。这些患者的分子机制尚不清楚。一些研究表明，这些患者可能在信号转导机制上存在异常。我们已经记录了血小板磷脂酶c - β 2， Gaq和蛋白激酶c - θ的特定缺陷。需要更新的方法来定义这些患者的分子缺陷，这些患者构成了一个未开发的新信息库。我们现在使用Affymetrix微阵列应用全基因组血小板表达谱来证明，在患有遗传性血小板减少症的患者中，肌球蛋白轻链9 （MYL9，减少70倍）和其他基因的表达减少，血小板反应受损（包括肌球蛋白和pleckstrin磷酸化和GPIIb-llla激活），转录因子CBFA2（核心结合因子A2）的杂合突变。从而提供了表达谱确实可以应用于血小板功能障碍患者获得新见解的概念证明。迄今为止，微阵列技术尚未应用于此类患者。在这个项目中，我们提出了一种综合的方法，包括：a)详细的血小板机制的生化和功能研究，b)血小板表达谱，以及c)使用功能、突变、生化和免疫学方法对异常机制进行后续验证，以描述15例遗传性血小板功能障碍患者的分子机制。我们在所有相关方法方面都有丰富的经验。该项目是两个具有很强互补性专业知识的实验室之间的合作成果。它代表了基因组学和人类基因组计划的最新进展在一组经常遇到但特征极其缺乏的患者中的应用。我们的研究将为血小板机制和抗血栓治疗的潜在新靶点提供丰富的信息。

DESCRIPTION (provided by applicant): Despite tremendous advances in our understanding of platelet physiology, the underlying molecular mechanisms remain unknown in the vast majority of patients with inherited defects in platelet function. Mechanisms, such as deficiencies in membrane glycoproteins and the storage pool deficiency, are commonly considered but occur in a small proportion of patients. Most of these patients are characterized by a bleeding disorder, and impaired aggregation and dense granule secretion on platelet activation, and are currently lumped in a loosely defined group called "platelet secretion/activation defects." The molecular mechanisms in these patients are unknown. Several studies suggest that these patients may have abnormalities in the signal transduction mechanisms. We have documented specific defects in platelet phospholipase C-beta2, Gaq and protein kinase C-theta. Newer approaches are required to define the molecular defects in such patients who constitute an untapped reservoir of new information. We have now applied genome-wide platelet expression profiling using the Affymetrix microarrays to demonstrate a unique decrease in expression of myosin light chain 9 (MYL9, 70 fold decrease) and other genes in a patient with an inherited thrombocytopenia, impaired platelet responses (including myosin and pleckstrin phosphorylation and GPIIb-llla activation), and a heterozygous mutation in transcription factor CBFA2 (Core-binding factor A2), thereby providing proof of concept that expression profiling can indeed be applied to obtain new insights in patients with platelet dysfunction. The microarray technology has hitherto not been applied to such patients. In this project, we propose an integrated approach encompassing, a) detailed biochemical and functional studies on platelet mechanisms, b) platelet expression profiling and c) subsequent validation of the aberrant mechanisms using functional, mutational, biochemical and immunological approaches, to delineate the molecular mechanisms in 15 patients with inherited platelet dysfunction. We have extensive experience in all of the involved approaches. This project is a collaborative effort between two laboratories with strong complementary expertise. It represents application of the recent advances in genomics and the Human Genome Project to a group of patients who are frequently encountered but extremely poorly characterized. Our studies will provide a wealth of information on platelet mechanisms and on potential new targets for antithrombotic therapy.