Oxidative stress induces phosphorylation of neuronal NOS in cardiomyocytes through AMP-activated protein kinase (AMPK).
Neuronal nitric oxide synthase (nNOS) plays a critical role in regulating cardiomyocyte function. nNOS was reported to decrease superoxide production in the myocardium by inhibiting the function of xanthine oxidoreductase. However, the effect of oxidative stress on nNOS in cardiomyocytes has not been determined. We report here that brief exposure of HL-1 cardiomyocytes to hydrogen peroxide (H2O2) induces phosphorylation of nNOS at serine 1412. This increase in phosphorylation was concomitant with increased nitric oxide (NO) production. Prolonged exposure to the oxidant, however, resulted in decreased expression of the protein. H2O2 treatment for short periods also stimulated phosphorylation of AKT and AMPK. H2O2-induced phosphorylation of nNOS was reduced when AMPK activity was inhibited by compound C, suggesting that AMPK is a mediator of oxidative stress-induced phosphorylation of nNOS. However, inhibition of AKT activity by the pan AKT inhibitor, AKTi, had no effect on nNOS phosphorylation caused by H2O2. These data demonstrate the novel regulation of nNOS phosphorylation and expression by oxidative stress.
Department of Biochemistry, The University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Dr., San Antonio, TX 78229, USA. Electronic address: KarR@uthscsa.edu.
Rekha
R
Kar
Department of Biochemistry, The University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Dr., San Antonio, TX 78229, USA. Electronic address: KelloggDL@livemail.uthscsa.edu.
Dean L
DL
Kellogg
Department of Biochemistry, The University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Dr., San Antonio, TX 78229, USA. Electronic address: roman@uthscsa.edu.
Linda J
LJ
Roman
D055372:AMP-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000818:Animals; D002460:Cell Line; D006861:Hydrogen Peroxide / Q000494:pharmacology; D051379:Mice; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism; D052248:Nitric Oxide Synthase Type I / Q000378:metabolism*; D016877:Oxidants / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors
D016877:Oxidants; D047428:Protein Kinase Inhibitors; D009569:Nitric Oxide; D006861:Hydrogen Peroxide; D052248:Nitric Oxide Synthase Type I; C496321:Nos1 protein, mouse; D051057:Proto-Oncogene Proteins c-akt; D055372:AMP-Activated Protein Kinases
AMP-Activated protein kinase; Cardiomyocyte; Neuronal nitric oxide synthase; Oxidative stress; Phosphorylation