Oscillatory shear stress induces mitochondrial superoxide production: implication of NADPH oxidase and c-Jun N[H.sub.2]-terminal kinase signaling

Fluid shear stress is intimately linked with vascular oxidative stress and atherosclerosis. We posited that atherogenic oscillatory shear stress (OSS) induced mitochondrial superoxide (mt[O.sub.2.sup.*-]) production via NADPH oxidase and c-Jun N[H.sub.2]-terminal kinase (JNK-1 and JNK-2) signaling. In bovine aortic endothelial cells, OSS (±3 dyn/[cm.sup.2]) induced JNK activation, which peaked at 1h, accompanied by an increase in fluorescein isothiocyanate-conjugated JNK fluorescent and MitoSOX Red (specific for mt[O.sub.2.sup.*-] production) intensities. Pretreatment with apocynin (NADPH oxidase inhibitor) or N-acetyl cysteine (antioxidant) significantly attenuated OSS-induced JNK activation. Apocynin further reduced OSS-mediated dihydroethidium and MitoSOX Red intensities specific for cytosolic [O.sub.2.sup.*-] and mt[O.sub.2.sup.*-] production, respectively. As a corollary, transfecting bovine aortic endothelial cells with JNK siRNA (siJNK) and pretreating with SP600125 (JNK inhibitor) significantly attenuated OSS-mediated mt[O.sub.2.sup.*-] production. Immunohistochemistry on explants of human coronary arteries further revealed prominent phosphorylated JNK staining in OSS-exposed regions. These findings indicate that OSS induces mt[O.sub.2.sup.*-] production via NADPH oxidase and JNK activation relevant for vascular oxidative stress. Antioxid. Redox Signal. 15, 1379-1388.