SIGNAL TRANSDUCTION DEFECTS IN HUMAN PLATELETS

描述：血小板在止血和先天性疾病中起主要作用。 血小板功能缺陷与出血症状有关。 这个项目的目标是定义潜在的生化机制 先天性血小板功能障碍患者的血小板功能障碍 从而加深了我们对正常血小板的了解 激活机制对开发新的治疗方法至关重要 治疗出血和血栓性疾病的策略。绝大多数人 先天性血小板缺陷症患者的特征通常是 活化时的聚集反应和致密颗粒分泌受损； 它们大多有正常的致密颗粒储存区。这些病人被集中在一起 归入一个定义松散的组，称为“血小板分泌缺陷”或 “激活缺陷。”在它们中，潜在的生化和分子 机制完全未知。需要检验的假设是，这些 患者在信号转导机制上存在缺陷。这个项目 重点关注申请者到目前为止已经证明的特定患者 与信号有关的两种主要蛋白质的未知缺陷 转导机制，即a)磷脂酶C(目标1)和b) GTP结合蛋白Gaq(目标2)。这些蛋白质在体内起着重要的作用 广泛细胞中的细胞信号机制。详细研究在 两名患者提示PLC激活异常，其激活程度降低 PLC-b2的表达。在《目标1》中，拉奥博士将描述分子缺陷 在PLC-b2中克隆、测序并表达PLC-b2的cDNA。变种人 对PLC-b2进行了研究。在目标2中，申请者将描述 1例G蛋白功能受损患者的分子缺陷 与异常的钙动员、花生四烯酸释放和 到目前为止，还没有人描述过血小板Gaq亚基的选择性缺陷。在AIM Rao博士将研究这些患者的中性粒细胞和单核细胞，以 确定它们是否在信号转导机制和 明确对白细胞功能的影响。这个项目代表着 应用最先进的技术来定义分子 一组患者的血小板功能障碍的机制 目前的特点很差，并造成了新的未开发的酸味 信息。这些研究将提供关于两个角色的新信息 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.