Oscillatory shear stress upregulation of endothelial nitric oxide synthase requires intracellular hydrogen peroxide and CaMKII

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• 作者：Cai ; Hua ; McNally ; Joseph S. ; Weber ; Martina ; Harrison ; David G.
• 关键词：H₂O₂ ; Oscillatory shear stress ; NO^&bull ; ; eNOS ; Calcium/calmodulin-dependent protein kinase II ; Unidirectional laminar shear stress
• 刊名：Journal of Molecular and Cellular Cardiology
• 出版年：2004
• 出版时间：July, 2004
• 年：2004
• 卷：37
• 期：1
• 页码：121-125
• 全文大小：331 K

文摘

We have previously shown that hydrogen peroxide (H₂O₂) upregulates endothelial nitric oxide synthase (eNOS) expression via a calcium/calmodulin-dependent protein kinase II (CaMKII)-mediated mechanism whereas it also acutely activates eNOS enzyme. We hypothesized that oscillatory shear stress (OSS), which stimulates endogenous H₂O₂, would have effects on eNOS expression and function similar to that of exogenous H₂O₂. Exposure of bovine aortic endothelial cells to OSS (±15 dynes/cm²) increased eNOS mRNA expression by 3-fold. Pretreatment with either polyethylene glycol-catalase (PEG-CAT, a scavenger of H₂O₂) or KN93, an inhibitor of CaMKII, abolished this response. OSS activated CaMKII in an H₂O₂-dependent fashion whereas unidirectional laminar shear stress (LSS) inhibited CaMKII phosphorylation. Inhibition of c-Src (essential for LSS upregulation of eNOS) had no effect on OSS upregulation of eNOS. Additionally, OSS stimulated NO^• production acutely. Scavenging of H₂O₂ by PEG-CAT attenuated OSS stimulation of NO^• by 50 % whereas it had no effect on LSS regulation of NO^• production. These data suggest that intracellular H₂O₂ and CaMKII mediate OSS upregulation of eNOS. The acute activation of eNOS by OSS also partially requires H₂O₂. As OSS has been shown previously to stimulate sustained production of superoxide (O₂^•–) which would inactivate NO^•, these responses may represent attempted compensation to restore NO^• bioavailability in areas exposed to OSS. Simultaneous stimulation of O₂^•– and NO^• by this mechanism, however, could facilitate peroxynitrite formation and protein nitration, which may enhance atherosclerotic lesion formation. Both OSS and LSS upregulate eNOS expression but via different signaling mechanisms.