Oxidative stress and regulation of anti-oxidant enzymes in cytochrome P4502E1 transgenic mouse model of non-alcoholic fatty liver.
OBJECTIVE
Reactive oxygen species produced by cytochrome P4502E1 (CYP2E1) are believed to play a role in pathophysiology of non-alcoholic fatty liver disease (NAFLD). However, little is known about the expression, protein content and activity of anti-oxidant enzymes and the role of inducible nitric oxide synthase (iNOS), a source of reactive nitrogen species, in NAFLD. In the present study, we evaluate gene expression, protein content and activity of anti-oxidant enzymes, and iNOS, in a CYP2E1 overexpressing model of non-alcoholic fatty liver (NAFL).


METHODS
Non-transgenic (nTg) and CYP2E1 transgenic (Tg) mice were fed rodent chow for 8 months. Alanine aminotransferase (ALT), aspartate aminotransferase (AST), liver triglycerides, malondialdehyde and protein carbonyls were measured. Gene expression of NF-E2-related factor (Nrf2), superoxide dismutase-1, -2 (SOD-1,2), catalase (CAT), glutathione peroxidase (GPx), heme oxygenase-1 (HO-1) and iNOS were determined. Protein content, activity and nitrosylation of the enzymes were also measured.


RESULTS
Tg mice had greater CYP2E1 activity and histological liver injury. MDA and protein carbonyls were increased, indicating insufficient anti-oxidant response. Gene expression of Nrf2, CAT, GPx, HO-1 and iNOS were significantly increased. Protein content and enzyme activities of most anti-oxidant enzymes were not correspondingly increased. iNOS activity and nitrosylation of CAT and SOD was greater in Tg mice liver.


CONCLUSIONS
Hepatocyte-specific CYP2E1 overexpression results in increased oxidative stress and nitrosative stress. Several anti-oxidant enzymes are upregulated. Failure of corresponding increase in total protein and activity of anti-oxidant enzymes suggests modification/degradation, possibly by nitrosylation, due to increased iNOS activity in a CYP2E1 overexpressing NAFL mouse model.
Kathirvel
Elango
E
Research Service, VA Long Beach Healthcare System, Long Beach, California 90822, USA.
Chen
Philip
P
Morgan
Kengathevy
K
French
Samuel W
SW
Morgan
Timothy R
TR
D000818:Animals; D015153:Blotting, Western; D002374:Catalase / Q000096:biosynthesis / Q000235:genetics; D019392:Cytochrome P-450 CYP2E1 / Q000096:biosynthesis / Q000235:genetics*; D004195:Disease Models, Animal; D018450:Disease Progression; D004591:Electrophoresis, Polyacrylamide Gel; D005234:Fatty Liver / Q000201:enzymology* / Q000235:genetics; D051547:Heme Oxygenase-1 / Q000096:biosynthesis / Q000235:genetics; D047468:Immunoprecipitation; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D051267:NF-E2-Related Factor 2 / Q000096:biosynthesis / Q000235:genetics; D052247:Nitric Oxide Synthase Type II / Q000096:biosynthesis / Q000235:genetics*; D018384:Oxidative Stress / Q000502:physiology*; D012313:RNA / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013482:Superoxide Dismutase / Q000096:biosynthesis / Q000235:genetics; D000072105:Superoxide Dismutase-1; D015854:Up-Regulation
D051267:NF-E2-Related Factor 2; D012313:RNA; D002374:Catalase; D019392:Cytochrome P-450 CYP2E1; D052247:Nitric Oxide Synthase Type II; D051547:Heme Oxygenase-1; C000606291:Sod1 protein, mouse; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1