Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10738858 | Free Radical Biology and Medicine | 2005 | 15 Pages |
Abstract
Endothelial dysfunction is characterized by increased levels of reactive oxygen species (ROS) and a prothrombotic state. The mechanisms linking thrombosis to ROS production in the endothelium are not well understood. We investigated the role of thrombin in regulating NADPH oxidase-dependent ROS production and expression of its subunit p22phox in the endothelial cell line EaHy926. Thrombin elicited a biphasic increase in ROS generation peaking within 15 min, but also at 3 h. The delayed response was accompanied by increased p22phox mRNA and protein expression. Two-photon confocal laser microscopy showed colocalization between p22phox and ROS production. Antioxidant treatment with vitamin C or diphenyleneiodonium abrogated thrombin-induced ROS production and p22phox expression, whereas H2O2 elevated ROS production and p22phox levels. Both responses were dependent on p38 MAP kinase and phosphatidylinositol-3-kinase (PI3 kinase)/Akt. Finally, p22phox was required for thrombin- or H2O2-stimulated proliferation. These data show that thrombin rapidly increases ROS production in endothelial cells, resulting, via activation of p38 MAP kinase and PI3 kinase/Akt, in upregulation of p22phox accompanied by a delayed increase in ROS generation and enhanced proliferation. These findings suggest a positive feedback mechanism whereby ROS, possibly generated by the NADPH oxidase, lead to elevated levels of p22phox and, thus, sustained ROS generation as is observed in endothelial dysfunction.
Keywords
DMEMECFPDcfHBSSCM-H2DCFDADPIDHR5-bromo-2′-deoxyuridineERK1/2l-NAMEMAPKDulbecco's modified Eagle's mediump38 MAPKBrdUdihydrorhodamine-123dihydroethidiumDiphenyleneiodoniumHanks' balanced salt solutionnitro-l-arginine methyl esterhypoxanthine, aminopterin, thymidineDHEmitogen activated protein kinasep38 mitogen activated protein kinaseHATextracellular regulated kinase
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Authors
Talija Djordjevic, Alexej Pogrebniak, Rachida S. BelAiba, Steve Bonello, Christoph Wotzlaw, Helmut Acker, John Hess, Agnes Görlach,