Redox regulation of the rat hepatocyte iNOS promoter.
BACKGROUND
The purpose of this study was to define the redox sensitive cis-acting transcriptional mechanisms that regulate inducible nitric oxide synthase (iNOS) promoter function in the hepatocyte.


METHODS
Clonal deletion constructs of the rat hepatocyte iNOS promoter (Genbank X95629; 1845 base pair)-reporter plasmid were transiently transfected into HepG2 cells treated with IL-1 beta and IL-1 beta + hydrogen peroxide.


RESULTS
A segment of the promoter upstream from nucleotide -1126 was associated with redox-sensitive augmentation of promoter activity. Site-directed mutagenesis of 2 antioxidant response elements (AREs) was combined with transfection analysis to demonstrate that mutation of the ARE at nt-1347 ablated oxidant stress-mediated activation of the iNOS promoter.


CONCLUSIONS
This ARE conveys the redox-sensitive response of the rat iNOS promoter. Hepatocyte iNOS expression is a novel and, as yet, poorly described antioxidant mechanism that is cytokine and redox sensitive and that plays a pleuripotent regulatory role in hepatocellular function in the face of sepsis and shock.
Punzalan
C
C
Department of Surgery, Georgetown University Medical Center, Washington, DC, USA.
Cai
C
C
Schroeder
R A
RA
Kuo
P C
PC
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D002478:Cells, Cultured; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology; D008099:Liver / Q000201:enzymology*; D019001:Nitric Oxide Synthase / Q000235:genetics*; D052247:Nitric Oxide Synthase Type II; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D011401:Promoter Regions, Genetic; D051381:Rats; D020218:Response Elements
D000975:Antioxidants; D007375:Interleukin-1; D006861:Hydrogen Peroxide; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat