HUMAN PLATELET ACTIVATION AND PHOSPHOLIPID METABOLISM

本申请中描述的实验集中于表征， 调节和生理功能的相对最近描述的 一组作用于磷脂酰肌醇的激酶。 已知的酶 作为磷脂酰肌醇3-K（PI 3-K）。 涉及这些酶的反应是 通过放射性标记产物形成和蛋白质印迹监测。 博士 Rittenhouse进行了广泛的初步研究， PI 3-K活性的抑制剂对于信号级联反应是重要的， 在最重要的功能反应中达到高潮， 血小板-凝聚和聚集。 抑制PI 3-K阻断激动剂- 激活的糖蛋白Iib/IIIa，整合素， 纤维蛋白原与血小板结合。 这一现象已被发现， GPIIb/IIIa抗体，称为PAC-1。 里滕豪斯博士将研究 广泛的因素清单，调节激活和特异性 PI 3-Ks和PI 3-Ks与细胞骨架的连接。 的因素之一 要研究的是：蛋白激酶，GTP结合蛋白，细胞骨架蛋白， 成分，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促进蛋白磷酸化 当加入到透化血小板中时。 参与此过程的激酶 磷酸化尚未被鉴定。 的实验 透化血小板似乎与完整血小板相关，因为 渥曼青霉素抑制活化的细胞中特定蛋白的磷酸化 和向透化血小板中加入PI（3，4，5）P3 克服了渥曼青霉素对蛋白质磷酸化的抑制作用。 其他实验设计用于检查和表征两种新的， 另外的PI 3-K：PI 3-K（θ）和PI 3-K（σ）。 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.