NO-mediated regulation of NAD(P)H oxidase by laminar shear stress in human endothelial cells

• Published in: The Journal of physiology Vol. 576; no. 2; pp. 557 - 567
• Main Authors: Duerrschmidt, Nicole, Stielow, Claudia, Muller, Gregor, Pagano, Patrick J., Morawietz, Henning
• Format: Journal Article
• Language: English
• Published: Oxford, UK The Physiological Society 15.10.2006; Blackwell Publishing Ltd; Blackwell Science Inc
• Subjects: Basement Membrane; Cardiovascular; Cells, Cultured; Down-Regulation - drug effects; Down-Regulation - physiology; Endothelium, Vascular - cytology; Endothelium, Vascular - metabolism; Enzyme Inhibitors - pharmacology; Humans; Membrane Glycoproteins - genetics; Membrane Glycoproteins - metabolism; NADPH Oxidase 2; NADPH Oxidases - genetics; NADPH Oxidases - metabolism; NG-Nitroarginine Methyl Ester - pharmacology; Nitric Oxide - genetics; Nitric Oxide - metabolism; Nitric Oxide Synthase Type III - genetics; Nitric Oxide Synthase Type III - metabolism; Oxygen - metabolism; RNA, Messenger - genetics; RNA, Messenger - metabolism; Stress, Mechanical; Superoxides - metabolism; Up-Regulation - drug effects; Up-Regulation - physiology
• DOI: 10.1113/jphysiol.2006.111070
• ISSN: 0022-3751

The flowing blood generates shear stress at the endothelial cell surface. In endothelial cells, NAD(P)H oxidase complexes have been identified as major sources of superoxide anion (·O 2 − ) formation. In this study, we analysed the effect of laminar shear stress on ·O 2 − formation by cytochrome c reduction assay and on NAD(P)H oxidase subunit expression by standard calibrated competitive reverse transcription-polymerase chain reaction and Western blot in human endothelial cells. Primary cultures of human umbilical vein endothelial cells were exposed to laminar shear stress in a cone-and-plate viscometer for up to 24 h. Short-term application of shear stress transiently induced ·O 2 − formation. This was inhibited by NAD(P)H oxidase inhibitor gp91ds- tat , but NAD(P)H oxidase subunit expression was unchanged. Long-term arterial laminar shear stress (30 dyne cm −2 , 24 h) down-regulated ·O 2 − formation, and mRNA and protein expression of NAD(P)H oxidase subunits Nox2/gp91 phox and p47 phox . In parallel, endothelial NO formation and eNOS, but not Cu/Zn SOD, protein expression was increased. Down-regulation of ·O 2 − formation, gp91 phox and p47 phox expression by long-term laminar shear stress was blocked by l -NAME. NO donor DETA-NO down-regulates ·O 2 − formation, gp91 phox and p47 phox expression in static cultures. In conclusion, our data suggest a transient activation of ·O 2 − formation by short-term shear stress, followed by a down-regulation of endothelial NAD(P)H oxidase in response to long-term laminar shear stress. NO-mediated down-regulation by shear stress preferentially affects the gp91 phox /p47 phox -containing NAD(P)H oxidase complex. This mechanism might contribute to the regulation of endothelial NO/·O 2 − balance and the vasoprotective potential of physiological levels of laminar shear stress.