title: Role of Nrf2 in preventing ethanol-induced oxidative stress and lipid accumulation.
abstract: Oxidative stress and lipid accumulation play important roles in alcohol-induced liver injury. Previous reports showed that, in livers of nuclear factor erythroid 2-related factor 2 (Nrf2)-activated mice, genes involved in antioxidant defense are induced, whereas genes involved in lipid biosynthesis are suppressed. To investigate the role of Nrf2 in ethanol-induced hepatic alterations, Nrf2-null mice, wild-type mice, kelch-like ECH-associated protein 1-knockdown (Keap1-KD) mice with enhanced Nrf2, and Keap1-hepatocyte knockout (Keap1-HKO) mice with maximum Nrf2 activation, were treated with ethanol (5 g/kg, po). Blood and liver samples were collected 6h thereafter. Ethanol increased alanine aminotransferase and lactate dehydrogenase activities as well as thiobarbituric acid reactive substances in serum of Nrf2-null and wild-type mice, but not in Nrf2-enhanced mice. After ethanol administration, mitochondrial glutathione concentrations decreased markedly in Nrf2-null mice but not in Nrf2-enhanced mice. H(2)DCFDA staining of primary hepatocytes isolated from the four genotypes of mice indicates that oxidative stress was higher in Nrf2-null cells, and lower in Nrf2-enhanced cells than in wild-type cells. Ethanol increased serum triglycerides and hepatic free fatty acids in Nrf2-null mice, and these increases were blunted in Nrf2-enhanced mice. In addition, the basal mRNA and nuclear protein levels of sterol regulatory element-binding protein 1(Srebp-1) were decreased with graded Nrf2 activation. Ethanol further induced Srebp-1 mRNA in Nrf2-null mice but not in Nrf2-enhanced mice. In conclusion, Nrf2 activation prevented alcohol-induced oxidative stress and accumulation of free fatty acids in liver by increasing genes involved in antioxidant defense and decreasing genes involved in lipogenesis.
authors.affiliation: Department of Pharmacology, Toxicology, and Therapeutics, University of Kansas Medical Center, Kansas City, KS 66160, USA.
authors.forename: Kai Connie
authors.initials: KC
authors.lastname: Wu
authors.forename: Jie
authors.initials: J
authors.lastname: Liu
authors.forename: Curtis D
authors.initials: CD
authors.lastname: Klaassen
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000502:physiology; D000410:Alanine Transaminase / Q000378:metabolism; D000818:Animals; D003598:Cytoskeletal Proteins / Q000502:physiology; D000431:Ethanol / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D005230:Fatty Acids, Nonesterified / Q000032:analysis; D000072019:Kelch-Like ECH-Associated Protein 1; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D050356:Lipid Metabolism / Q000187:drug effects; D015227:Lipid Peroxidation / Q000187:drug effects; D008055:Lipids / Q000032:analysis / Q000096:biosynthesis; D008099:Liver / Q000737:chemistry / Q000187:drug effects*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism; D051267:NF-E2-Related Factor 2 / Q000502:physiology*; D018384:Oxidative Stress / Q000187:drug effects*; D017382:Reactive Oxygen Species / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D003598:Cytoskeletal Proteins; D005230:Fatty Acids, Nonesterified; C117301:Keap1 protein, mouse; D000072019:Kelch-Like ECH-Associated Protein 1; D008055:Lipids; D051267:NF-E2-Related Factor 2; C495636:Nfe2l2 protein, mouse; D017382:Reactive Oxygen Species; D000431:Ethanol; D007770:L-Lactate Dehydrogenase; D000410:Alanine Transaminase