Potentiation of nitric oxide synthase expression by superoxide in interleukin 1 beta-stimulated rat mesangial cells.
Exposure of mesangial cells to superoxide, generated by the hypoxanthine/xanthine oxidase system or by the redox cycler 2,3-dimethoxy-1,4-naphthoquinone caused a concentration-dependent amplification of interleukin (IL)-1beta-stimulated nitrite production. The effect of superoxide was accompanied by an increase in inducible nitric oxide synthase (iNOS) protein and iNOS mRNA levels. Incubation of mesangial cells with superoxide alone did not induce iNOS expression. To elucidate whether the increase of iNOS expression is due to transcriptional upregulation we fused a 4.5-kb genomic iNOS fragment that contains the transcriptional start site of the rat iNOS gene to a luciferase reporter gene. In transient transfection studies, superoxide caused a 10-fold augmentation of iNOS promoter activity in IL-1beta-challenged mesangial cells. Our data identify superoxide as a co-stimulatory factor amplifying cytokine-induced iNOS gene expression and subsequent nitric oxide (NO) synthesis.
Zentrum der Pharmakologie, Klinikum der Johann Wolfgang Goethe-Universität, Frankfurt am Main, Germany.
K F
KF
Beck
W
W
Eberhardt
S
S
Walpen
M
M
Apel
J
J
Pfeilschifter
D000818:Animals; D004357:Drug Synergism; D004790:Enzyme Induction / Q000187:drug effects / Q000235:genetics; D005920:Glomerular Mesangium / Q000166:cytology / Q000201:enzymology* / Q000378:metabolism; D006801:Humans; D007375:Interleukin-1 / Q000494:pharmacology*; D051379:Mice; D009569:Nitric Oxide / Q000502:physiology; D019001:Nitric Oxide Synthase / Q000096:biosynthesis* / Q000187:drug effects / Q000235:genetics; D052247:Nitric Oxide Synthase Type II; D011401:Promoter Regions, Genetic / Q000502:physiology; D051381:Rats; D017382:Reactive Oxygen Species / Q000502:physiology; D013481:Superoxides / Q000494:pharmacology*
D007375:Interleukin-1; D017382:Reactive Oxygen Species; D013481:Superoxides; D009569:Nitric Oxide; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; C496318:Nos2 protein, rat