Rezaul K, Yanagi S, Sada K, Taniguchi T, Yamamura H
Department of Biochemistry, Fukui Medicial School, Japan.
Thromb Haemost. 1994 Dec;72(6):937-41.
It has been demonstrated that activation of platelets by platelet-activating factor (PAF) results in a dramatic increase in tyrosine phosphorylation of several cellular proteins. We report here that p72syk is a potential candidate for the protein-tyrosine phosphorylation following PAF stimulation in porcine platelets. Immunoprecipitation kinase assay revealed that PAF stimulation resulted in a rapid activation of p72syk which peaked at 10 s. The level of activation was found to be dose dependent and could be completely inhibited by the PAF receptor antagonist, CV3988. Phosphorylation at the tyrosine residues of p72syk coincided with activation of p72syk. Pretreatment of platelets with aspirin and apyrase did not affect PAF induced activation of p72syk. Furthermore, genistein, a potent protein-tyrosine-kinase inhibitor, diminished PAF-induced p72syk activation and Ca2+ mobilization as well as platelet aggregation. These results suggest that p72syk may play a critical role in PAF-induced aggregation, possibly through regulation of Ca2+ mobilization.
已证明血小板活化因子（PAF）激活血小板会导致几种细胞蛋白的酪氨酸磷酸化显著增加。我们在此报告，p72syk是猪血小板中PAF刺激后蛋白酪氨酸磷酸化的潜在候选蛋白。免疫沉淀激酶分析显示，PAF刺激导致p72syk迅速激活，在10秒时达到峰值。发现激活水平呈剂量依赖性，并且可被PAF受体拮抗剂CV3988完全抑制。p72syk酪氨酸残基的磷酸化与p72syk的激活同时发生。用阿司匹林和腺苷双磷酸酶预处理血小板不影响PAF诱导的p72syk激活。此外，染料木黄酮是一种有效的蛋白酪氨酸激酶抑制剂，可减少PAF诱导的p72syk激活、Ca2+动员以及血小板聚集。这些结果表明，p72syk可能在PAF诱导的聚集中起关键作用，可能是通过调节Ca2+动员来实现的。
