SIGNAL TRANSDUCTION DEFECTS IN HUMAN PLATELETS

描述：血小板在止血和先天性 血小板功能的缺陷与出血表现有关。 该项目的目标是确定潜在的生化机制 先天性血小板功能障碍患者的血小板功能障碍 从而增强我们对正常血小板的理解 激活机制，这是至关重要的新的治疗发展 出血和血栓性疾病的治疗策略。 绝大多数 具有先天性血小板缺陷的患者通常具有以下特征： 活化时聚集反应和致密颗粒分泌受损; 它们中的大多数具有正常的致密颗粒储存。 这些病人被归为一类 分为一个松散定义的组，称为“血小板分泌缺陷”， “激活缺陷。“在它们中， 机制完全未知。 要检验的假设是， 患者在信号传导机制上存在缺陷。 这个项目 侧重于申请人迄今为止已证明的特定患者 参与信号传导的两种主要蛋白质的未描述缺陷 转导机制，即a）磷脂酶C（Aim 1），和B） GTP结合蛋白Gaq（Aim 2）。 这些蛋白质发挥着重要作用， 细胞信号传导机制。 详细研究 两名患者提示PLC激活的独特异常， PLC-b2表达。 在目标1中，Rao博士将描述分子缺陷 在PLC-b2中通过克隆、测序和表达PLC-b2 cDNA。 突变 将研究PLC-B2。 在目标2中，申请者将描述 G蛋白功能受损患者的分子缺陷 与异常的Ca 2+动员、花生四烯酸释放和 血小板Gaq亚单位迄今未描述的选择性缺陷。 在Aim中 Rao博士将研究这些患者的中性粒细胞和单核细胞， 确定它们是否在信号转导机制上存在缺陷， 定义对白细胞功能的影响。 该项目代表了 应用最先进的技术来确定分子 血小板功能障碍的机制在一组患者谁是非常 目前特征不佳，并提供了一个新的未开发的酸 信息. 这些研究将提供关于两个因素的作用的新信息。 血小板信号转导机制中的主要蛋白质PLC-b2和Gaq。

DESCRIPTION: Platelets play a major role in hemostasis and congenital defects in platelet function are associated with bleeding manifestations. The goal of this project is to define the biochemical mechanisms underlying the platelet dysfunction in patients with congenital platelet function defects and thereby enhance our understanding of the normal platelet activation mechanisms which is vital to the development of newer therapeutic strategies for both bleeding and thrombotic disorders. The vast majority of patients with congenital platelet defects are generally characterized by impaired aggregation responses and dense granule secretion on activation; most of them have normal dense granule stores. These patients are lumped into a loosely defined group called "platelet secretion defects" or "activation defects." In them the underlying biochemical and molecular mechanisms are totally unknown. The hypothesis to be tested is that these patients have defects in the signal transduction mechanisms. This project focuses on specific patients in whom the applicant has demonstrated hitherto undescribed deficiencies in two major proteins involved in signal transduction mechanisms, namely, a) phospholipase C (Aim 1), and b) GTP-binding protein Gaq (Aim 2). These proteins play fundamental roles in cellular signaling mechanisms in a wide array of cells. Detailed studies in two patients suggest an unique abnormality in PLC activation with decreased PLC-b2 expression. In Aim 1 Dr. Rao will characterize the molecular defect in PLC-b2 by cloning, sequencing and expressing PLC-b2 CDNA. The mutant PLC-b2 will be studied. In Aim 2, the applicant will characterize the molecular defect in a patient identified with impaired G-protein-function associated with abnormal Ca2+ mobilization, arachidonate release and a hitherto undescribed selective deficiency in platelet Gaq subunit. In Aim 3, Dr. Rao will study neutrophils and monocytes from these patients to determine if they share the defect in signal transduction mechanisms and define the impact on leucocyte function. This project represents application of state-of-the-art techniques to define the molecular mechanisms of platelet dysfunction in a group of patients who are very poorly characterized at present and contribute an untapped sour of new information. These studies will provide new information on the role of two major proteins, PLC-b2 and Gaq, in platelet signal transduction mechanisms.