RAFTK/Pyk2 involvement in platelet activation is mediated by phosphoinositide 3-kinase.
RAFTK/Pyk2 involvement in platelet activation is mediated by phosphoinositide 3-kinase.
复制标题
RAFTK/Pyk2 参与血小板活化是由磷酸肌醇 3-激酶介导的。
DOI：
10.1046/j.1365-2141.2001.02894.x
复制
发表时间：
2001
影响因子：
6.5
通讯作者：
Avraham,H
中科院分区：
文献类型：
--
作者：
Koziak,K;Kaczmarek,E;Park,SY;Fu,Y;Avraham,S;Avraham,H
不同的激动剂激活血小板会启动一个信号级联，涉及几种蛋白激酶的磷酸化，这些蛋白激酶控制着关键的调节事件。先前，我们证明了相关的粘附局灶酪氨酸激酶（RAFTK, Pyk2）参与血小板激活的早期阶段，独立于整合素和糖蛋白IIb-IIIa的激活。在这项研究中，我们证明了血小板激活时，RAFTK与磷酸肌肽3激酶（PI3K）共同免疫沉淀，凝血酶、ADP和胶原诱导PI3K和RAFTK的磷酸化。低剂量的凝血酶（0.015 U/ml）以PI3K活性依赖的方式诱导RAFTK磷酸化和血小板聚集，而高剂量的凝血酶（0.1 U/ml）以PI3K活性独立的方式诱导这些事件。ADP和胶原也以PI3K活性依赖的方式诱导RAFTK磷酸化和血小板聚集，类似于低剂量凝血酶。此外，蛋白酪氨酸磷酸酶活性与血小板活化反应中的RAFTK相关，并且发现是蛋白酪氨酸磷酸酶- 2 （SHP - 2）的活性。SHP‐2与RAFTK的关联依赖于PI3K，并随着RAFTK磷酸化而增加。综上所述，我们的结果强烈表明RAFTK参与血小板活化是通过PI3K途径介导的。
Platelet activation by different agonists initiates a signalling cascade involving the phosphorylation of several protein kinases, which control key regulatory events. Previously, we demonstrated that the related adhesion focal tyrosine kinase (RAFTK, Pyk2) was involved in an early phase of platelet activation, independent of integrin and glycoprotein IIb–IIIa activation. In this study, we demonstrate that RAFTK is co‐immunoprecipitated with phosphoinositide 3‐kinase (PI3K) upon platelet activation, and that thrombin, ADP and collagen induced the phosphorylation of both PI3K and RAFTK. A low dose of thrombin (0·015 U/ml) induced RAFTK phosphorylation and platelet aggregation in a PI3K activity‐dependent manner, whereas a high dose of thrombin (0·1 U/ml) induced these events in a PI3K activity‐independent manner. ADP and collagen also induced RAFTK phosphorylation and platelet aggregation in a PI3K activity‐dependent manner, similar to that of the low‐dose thrombin. Furthermore, protein tyrosine phosphatase activity was associated with RAFTK in response to platelet activation, and was found to be that of protein tyrosine phosphatase‐2 (SHP‐2). The association of SHP‐2 with RAFTK was PI3K‐dependent and was increased upon RAFTK phosphorylation. Taken together, our results strongly suggest that the involvement of RAFTK in platelet activation is mediated via the PI3K pathway.