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ROLE OF C-KINASE IN PLATELET ARACHIDONATE RELEASE

C-激酶在血小板花生四烯酸释放中的作用

基本信息

批准号：
3471190
负责人：
STEPHEN P HALENDA
金额：
$ 9.45万
依托单位：
UNIVERSITY OF MISSOURI-COLUMBIA
依托单位国家：
美国
项目类别：
财政年份：
1988
资助国家：
美国
起止时间：
1988-04-01 至 1994-03-31
项目状态：
已结题

项目摘要

Aside from its crucial role in the normal hemostatic process, the blood platelet is firmly implicated in the pathogenesis of thrombosis and other vascular diseases; thus it is important to understand the cellular mechanisms which regulate platelet function. Formation of the key platelet activator thromboxane A2 during platelet aggregation is limited by the availability of its chemical precursor, arachidonic acid. This project seeks to clarify the poorly understood mechanism by which arachidonic acid mobilization in human platelets is governed. The roles of three major intracellular signals, Ca2+, the Ca2+/phospholipid-dependent protein kinase (C-kinase), and guanine nucleotide-binding proteins (N-proteins) in the cellular mechanism of arachidonic acid release, will be studied in human platelets in experiments involving intact cells, permeabilized platelets, and platelet-derived subcellular preparations. Previous studies in intact platelets which suggest an involvement of C- kinase in Ca2+-dependent arachidonic acid release will be extended by examining the direct effect of purified C-kinase on the activity of phospholipase A2, the major lipolytic enzyme responsible for arachidonic acid liberation in stimulated platelets. Identification of the C-kinase substrate which mediates activation of phospholipase A2 will be sought. The possible involvement of endogenous phospholipase A2 inhibitors (lipocortins) and their regulation by C-kinase will be studied. And finally, the role of N- proteins will be investigated by using guanine nucleotides and pertussis toxin in permeabilized platelets and studying the effect of purified N-protein subunits on platelet phospholipase A2. Possible interactions among the different signal transducers (Ca2+, C-Kinase, N-proteins) for control of arachidonic acid release will be examined. The goals of this project and future studies are: (1) to identify the cellular factors which control the liberation of arachidonic acid, the precursor for prostaglandins, thromboxanes, and other biologically important substances; and (2) more broadly, to define the intra- and intercellular signalling pathways that regulate platelet aggregation and secretion, as these events are centrally involved in hemostasis and thrombosis.

除了它在正常止血过程中的关键作用外，血小板与糖尿病的发病机制密切相关血栓和其他血管疾病；因此，重要的是了解调节血小板的细胞机制功能。关键的血小板激活剂血栓烷的形成 A2在血小板聚集过程中受到其可用性的限制化学前体，花生四烯酸。这一项目旨在阐明鲜为人知的花生四烯酸人体血小板中的酸动员是受控制的。三种主要的细胞内信号，钙离子， Ca~(2+)/磷脂依赖蛋白激酶(C-K)，以及细胞内的鸟嘌呤核苷酸结合蛋白(N-蛋白) 花生四烯酸的释放机制将在人体内进行研究在涉及完整细胞的实验中，渗透的血小板血小板和血小板衍生的亚细胞制剂。上一首对完整血小板的研究表明，C-受体参与了依赖于钙离子的花生四烯酸释放中的激酶通过检测纯化的C-激酶的直接作用来扩展主要脂解酶磷脂酶A2的活性负责刺激血小板中花生四烯酸的释放。介导激活的C-激酶底物的鉴定将寻找磷脂酶A2。可能参与其中的内源性磷脂酶A2抑制剂(Lipocortins)及其我们将研究C-激酶的调节作用。最后，N-的作用- 蛋白质将通过使用鸟嘌呤核苷酸和百日咳毒素在通透性血小板中的表达及其作用研究血小板磷脂酶A2上N蛋白亚基的纯化。不同信号换能器之间可能的相互作用 (钙、C-激酶、N-蛋白)对花生四烯酸的控制将对释放进行检查。本项目和未来研究的目标是：(1)确定控制花生四烯酸释放的细胞因素酸，前列腺素、血栓烷和其他物质的前体生物上重要的物质；以及(2)更广泛地说，定义调节细胞内和细胞间的信号通路血小板聚集和分泌，因为这些事件是中枢的参与止血和血栓形成。