Maeda H, Inazu T, Nagai K, Maruyama S, Nakagawara G, Yamamura H
Department of Biochemistry, Fukui Medical School.
J Biochem. 1995 Jun;117(6):1201-8. doi: 10.1093/oxfordjournals.jbchem.a124845.
We previously reported that p72syk, a non-receptor tyrosine kinase, was activated maximally at 10 s after thrombin or thromboxane A2 stimulation, even in platelets that were not allowed to aggregate [Taniguchi et al. (1993) J. Biol. Chem. 268, 2277-2279; Maeda et al. (1993) Biochem. Biophys. Res. Commun. 197, 62-67]. Then, the change in the shape of porcine platelets induced by the thromboxane A2 analogue, STA2, and the role of protein-tyrosine kinases including p72syk in this response were evaluated, using the shape-change parameter. We show that p72syk activation is correlated with the disc-sphere change in a time- and dose-dependent manner following stimulation by STA2. Tyrphostin B44, a potent protein-tyrosine kinase inhibitor, reduced the thromboxane A2-evoked p72syk activation and the disc-sphere change in a dose-dependent manner. Furthermore, the translocation of p72syk to the cytoskeleton-rich fraction and an increase in the tyrosine phosphorylation of an about 120 kDa protein were observed during the disc-sphere change induced by STA2. These lines of evidence suggest that the activation of protein-tyrosine kinases such as p72syk may be involved in the disc-sphere change response in thromboxane A2-stimulated porcine platelets.
我们先前报道过，非受体酪氨酸激酶p72syk在凝血酶或血栓素A2刺激后10秒时被最大程度激活，即便在未发生聚集的血小板中也是如此[谷口等人（1993年）《生物化学杂志》268卷，2277 - 2279页；前田等人（1993年）《生物化学与生物物理研究通讯》197卷，62 - 67页]。然后，利用形状改变参数评估了血栓素A2类似物STA2诱导的猪血小板形状变化，以及包括p72syk在内的蛋白酪氨酸激酶在此反应中的作用。我们发现，在STA2刺激后，p72syk的激活与盘状 - 球状变化呈时间和剂量依赖性相关。强效蛋白酪氨酸激酶抑制剂酪氨酸磷酸化酶B44以剂量依赖性方式降低了血栓素A2诱发的p72syk激活及盘状 - 球状变化。此外，在STA2诱导的盘状 - 球状变化过程中，观察到p72syk向富含细胞骨架的部分转位，以及一种约120 kDa蛋白的酪氨酸磷酸化增加。这些证据表明，诸如p72syk之类的蛋白酪氨酸激酶的激活可能参与了血栓素A2刺激的猪血小板的盘状 - 球状变化反应。
