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Priming of Platelet α IIb β 3 by Oxidants Is Associated With Tyrosine Phosphorylation of β 3
Journal article   Open access   Peer reviewed

Priming of Platelet α IIb β 3 by Oxidants Is Associated With Tyrosine Phosphorylation of β 3

Kaikobad Irani, Youm Pham, Lindsay D. Coleman, Christine Roos, Glen E. Cooke, Amir Miodovnik, Nayeem Karim, Calvin C. Wilhide, Paul F. Bray and Pascal J. Goldschmidt-Clermont
Arteriosclerosis, thrombosis, and vascular biology, Vol.18(11), pp.1698-1706
11/1998
DOI: 10.1161/01.ATV.18.11.1698
url
https://doi.org/10.1161/01.ATV.18.11.1698View
Published (Version of record) Open Access

Abstract

Abstract —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 H 2 O 2 , a major cellular oxidant. Exposure to H 2 O 2 triggered platelet aggregation, but only when the platelets were stirred. Strong platelet aggregation induced by H 2 O 2 required the presence of the tyrosine phosphatase inhibitor sodium orthovanadate (NaVO 4 ) and was dependent on the participation of integrin α IIb β 3 (glycoprotein IIb-IIIa). A specific inhibitor of α IIb β 3 blocked platelet aggregation induced by H 2 O 2 and NaVO 4 , thus confirming that aggregation requires this receptor. In the presence of H 2 O 2 and NaVO 4 , multiple platelet substrates were phosphorylated on tyrosine. Such tyrosine kinase response was necessary but not sufficient to activate α IIb β 3 , as detected by binding of soluble fibrinogen to platelets. Stirring of the platelets exposed to H 2 O 2 and NaVO 4 was also needed to allow for binding of fibrinogen to α IIb β 3 . The tyrosine kinase inhibitor genistein was able to block platelet aggregation induced by H 2 O 2 and NaVO 4 , thus confirming that tyrosine kinase activity was needed to trigger α IIb β 3 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 H 2 O 2 and NaVO 4 . We found that β 3 was phosphorylated on tyrosine in platelets exposed to H 2 O 2 and NaVO 4 , even in the absence of aggregation. Hence, tyrosine phosphorylation of β 3 might contribute to the “priming” of α IIb β 3 induced by H 2 O 2 and NaVO 4 , whereby the receptor can become activated on stirring of the platelets.

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