Irani K, Pham Y, Coleman L D, Roos C, Cooke G E, Miodovnik A, Karim N, Wilhide C C, Bray P F, Goldschmidt-Clermont P J
Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Md, USA.
Arterioscler Thromb Vasc Biol. 1998 Nov;18(11):1698-706. doi: 10.1161/01.atv.18.11.1698.
Reactive oxygen species play an important role at the site of vascular injuries and arterial thromboses. We studied the mechanism mediating platelet aggregation induced by H2O2, a major cellular oxidant. Exposure to H2O2 triggered platelet aggregation, but only when the platelets were stirred. Strong platelet aggregation induced99032416 required the presence of the tyrosine phosphatase inhibitor sodium orthovanadate (NaVO4) and was dependent on the participation of integrin alphaIIbbeta3 (glycoprotein IIb-IIIa). A specific inhibitor of alphaIIbbeta3 blocked platelet aggregation induced by H2O2 and NaVO4, thus confirming that aggregation requires this receptor. In the presence of H2O2 and NaVO4, multiple platelet substrates were phosphorylated on tyrosine. Such tyrosine kinase response was necessary but not sufficient to activate alphaIIbbeta3, as detected by binding of soluble fibrinogen to platelets. Stirring of the platelets exposed to H2O2 and NaVO4 was also needed to allow for binding of fibrinogen to alphaIIbbeta3. The tyrosine kinase inhibitor genistein was able to block platelet aggregation induced by H2O2 and NaVO4, thus confirming that tyrosine kinase activity was needed to trigger alphaIIbbeta3 activation on stirring. N-Acetyl-L-cysteine, a cell-permeant antioxidant, blocked the tyrosine phosphorylation of platelet substrates and also the platelet aggregation induced by H2O2 and NaVO4. We found that beta3 was phosphorylated on tyrosine in platelets exposed to H2O2 and NaVO4, even in the absence of aggregation. Hence, tyrosine phosphorylation of beta3 might contribute to the "priming" of alphaIIbbeta3 induced by H2O2 and NaVO4, whereby the receptor can become activated on stirring of the platelets.
活性氧在血管损伤和动脉血栓形成部位发挥着重要作用。我们研究了由主要细胞氧化剂过氧化氢（H2O2）介导血小板聚集的机制。暴露于H2O2会引发血小板聚集，但仅在搅拌血小板时才会发生。强烈的血小板聚集诱导99032416需要酪氨酸磷酸酶抑制剂原钒酸钠（NaVO4）的存在，并且依赖于整合素αIIbβ3（糖蛋白IIb-IIIa）的参与。αIIbβ3的特异性抑制剂可阻断H2O2和NaVO4诱导的血小板聚集，从而证实聚集需要该受体。在H2O2和NaVO4存在的情况下，多种血小板底物的酪氨酸发生磷酸化。这种酪氨酸激酶反应对于激活αIIbβ3是必要的，但并不充分，这可通过可溶性纤维蛋白原与血小板的结合来检测。搅拌暴露于H2O2和NaVO4的血小板也需要，以便纤维蛋白原与αIIbβ3结合。酪氨酸激酶抑制剂染料木黄酮能够阻断H2O2和NaVO4诱导的血小板聚集，从而证实酪氨酸激酶活性是搅拌时触发αIIbβ3激活所必需的。细胞可渗透的抗氧化剂N-乙酰-L-半胱氨酸可阻断血小板底物的酪氨酸磷酸化以及H2O2和NaVO4诱导的血小板聚集。我们发现，即使在没有聚集的情况下，暴露于H2O2和NaVO4的血小板中β3的酪氨酸也会发生磷酸化。因此，β3的酪氨酸磷酸化可能有助于H2O2和NaVO4诱导的αIIbβ3的“预激活”，由此受体在搅拌血小板时可被激活。
