HUMAN PLATELET ACTIVATION AND PHOSPHOLIPID METABOLISM

本申请中描述的实验侧重于表征， 一种较新描述的调节和生理功能 作用于磷脂酰肌醇的一组激酶。这些酶是已知的 磷脂酰肌醇3-K(等电点3-K)。涉及这些酶的反应有 通过放射性标记产物形成和Western blotting进行监测。Dr。 Rittenhouse已经对一项具体的 PI3-K活性抑制物对信号转导具有重要意义 最终导致激活的最重要的功能反应 血小板--凝聚力和聚集性。抑制PI_3-K受体激动剂-- 激活的糖蛋白IIb/IIIa的刺激暴露，整合素 纤维蛋白原与血小板结合。这一现象已被 GPIIb/IIIa抗体，称为PAC-1。里滕豪斯博士将研究一种 广泛的调节因子的激活和特异性的清单 PI3-Ks和pI3-Ks与细胞骨架的连接。在这些因素中 需要研究的有：蛋白激酶、GTP结合蛋白、细胞骨架 以及一种重要的血小板蛋白--Pleckstrin。 里滕豪斯博士进行的其他初步实验表明， PI 3-K活性产物PI(3，4，5)P3促进蛋白质磷酸化 添加到通透性的血小板中。与此相关的激酶(S) 到目前为止，磷酸化还没有被确定。的实验。 通透性的血小板似乎与完整的血小板有关，因为 Wortmannin抑制激活的特定蛋白的磷酸化 和PI(3，4，5)P3加入到通透性的血小板中 克服了Wortmannin对蛋白质磷酸化的抑制作用。 其他实验旨在检查和表征两个新的、 额外的pI 3-K：pI 3-K(Theta)和pI 3-K(Sigma)。这些实验 代表了里滕豪斯博士的新研究方向。

Experiments described in this application focus on the characterization, regulation and physiological function of a relatively recently described group of kinases that act on phosphatidylinositosol. The enzymes are known as phosphoinositide 3-k (PI 3-K). Reactions involving these enzymes are monitored by radiolabeled product formation and Western blotting. Dr. Rittenhouse has carried out extensive preliminary studies with a specific inhibitor of PI 3-K activity is important for the signal cascade that culminates in the most important functional response of activated platelets-cohesion and aggregation. Inhibition of PI 3-K blocks agonist- stimulated exposure of activated glycoprotein Iib/IIIa, the integrin to which fibrinogen binds to platelets. This phenomenon has been detected by the GPIIb/IIIa antibody, known as PAC-1. Dr. Rittenhouse will study an extensive list of factors which regulate the activation and specificity of PI 3-Ks and the linkage of PI 3-Ks to the cytoskeleton. Among the factors to be studied are: Protein kinases, GTP-binding proteins, cytoskeletal components, and an important platelet protein-pleckstrin. Other preliminary experiments carried out by Dr. Rittenhouse have shown the product of PI 3-K activity, PI(3,4,5) P3, promotes protein phosphorylation when added to permeabilized platelets. The kinase(s) involved in this phosphorylation have not as yet been identified. The experiments on permeabilized platelets appear to be relevant to intact platelets, since wortmannin inhibits phosphorylation of specific proteins in activated platelets, and the addition of PI(3,4,5) P3 to permeabilized platelets overcomes the inhibitory effects of wortmannin on protein phosphorylation. Other experiment are designed to examine and characterize two new, additional PI 3-Ks:PI 3-K (theta) and PI 3-K(sigma). These experiments represent new research directions for Dr. Rittenhouse.