title: Differential Fmo3 gene expression in various liver injury models involving hepatic oxidative stress in mice.
abstract: Flavin-containing monooxygenase-3 (FMO3) catalyzes metabolic reactions similar to cytochrome P450 monooxygenase, however, most metabolites of FMO3 are considered non-toxic. Recent findings in our laboratory demonstrated Fmo3 gene induction following toxic acetaminophen (APAP) treatment in mice. The goal of this study was to evaluate Fmo3 gene expression in other diverse mouse models of hepatic oxidative stress and injury. Fmo3 gene regulation by Nrf2 was also investigated using Nrf2 knockout (Nrf2 KO) mice. In our studies, male C57BL/6J mice were treated with toxic doses of hepatotoxicants or underwent bile duct ligation (BDL, 10 days). Hepatotoxicants included APAP (400 mg/kg, 24-72 h), alpha-naphthyl isothiocyanate (ANIT; 50 mg/kg, 2-48 h), carbon tetrachloride (CCl4; 10 or 30 μL/kg, 24 and 48 h) and allyl alcohol (AlOH; 30 or 60 mg/kg, 6 and 24 h). Because oxidative stress activates nuclear factor (erythroid-derived 2)-like 2 (Nrf2), additional studies investigated Fmo3 gene regulation by Nrf2 using Nrf2 knockout (Nrf2 KO) mice. At appropriate time-points, blood and liver samples were collected for assessment of plasma alanine aminotransferase (ALT) activity, plasma and hepatic bile acid levels, as well as liver Fmo3 mRNA and protein expression. Fmo3 mRNA expression increased significantly by 43-fold at 12 h after ANIT treatment, and this increase translates to a 4-fold change in protein levels. BDL also increased Fmo3 mRNA expression by 1899-fold, but with no change in protein levels. Treatment of mice with CCl4 decreased liver Fmo3 gene expression, while no change in expression was detected with AlOH treatment. Nrf2 KO mice are more susceptible to APAP (400mg/kg, 72 h) treatment compared to their wild-type (WT) counterparts, which is evidenced by greater plasma ALT activity. The Fmo3 mRNA and protein expression increased in Nrf2 KO mice after APAP treatment. Collectively, not all hepatotoxicants that produce oxidative stress alter Fmo3 gene expression. Along with APAP, toxic ANIT treatment in mice markedly increased Fmo3 gene expression. While BDL increased the Fmo3 mRNA expression, the protein level did not change. The discrepancy with Fmo3 induction in cholestatic models, ANIT and BDL, is not entirely clear. Results from Nrf2 KO mice with APAP suggest that the transcriptional regulation of Fmo3 during liver injury may not involve Nrf2.
authors.affiliation: Department of Pharmaceutical Sciences, University of Connecticut, Storrs, CT, USA. Electronic address: swetha.rudraiah@uconn.edu.
authors.forename: Swetha
authors.initials: S
authors.lastname: Rudraiah
authors.affiliation: Department of Pharmacology and Toxicology, Rutgers University Ernest Mario School of Pharmacy, Piscataway, NJ, USA. Electronic address: jamie.moscovitz@rutgers.edu.
authors.forename: Jamie E
authors.initials: JE
authors.lastname: Moscovitz
authors.affiliation: Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, RI, USA. Electronic address: ajaydonepudi@gmail.com.
authors.forename: Ajay C
authors.initials: AC
authors.lastname: Donepudi
authors.affiliation: Drug Safety Research and Development, Pfizer Inc., Groton, USA. Electronic address: sarah.campion@pfizer.com.
authors.forename: Sarah N
authors.initials: SN
authors.lastname: Campion
authors.affiliation: Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, RI, USA. Electronic address: angela_slitt@ds.uri.edu.
authors.forename: Angela L
authors.initials: AL
authors.lastname: Slitt
authors.affiliation: Department of Pharmacology and Toxicology, Rutgers University Ernest Mario School of Pharmacy, Piscataway, NJ, USA. Electronic address: aleksunes@eohsi.rutgers.edu.
authors.forename: Lauren M
authors.initials: LM
authors.lastname: Aleksunes
authors.affiliation: Department of Pharmaceutical Sciences, University of Connecticut, Storrs, CT, USA. Electronic address: jose.manautou@uconn.edu.
authors.forename: José E
authors.initials: JE
authors.lastname: Manautou
mesh_terms: D000410:Alanine Transaminase / Q000097:blood; D000818:Animals; D001647:Bile Acids and Salts / Q000097:blood; D001652:Bile Ducts / Q000601:surgery; D015415:Biomarkers / Q000097:blood; D056486:Chemical and Drug Induced Liver Injury / Q000097:blood / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D002779:Cholestasis / Q000097:blood / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D004195:Disease Models, Animal; D015971:Gene Expression Regulation, Enzymologic; D008026:Ligation; D008099:Liver / Q000201:enzymology* / Q000473:pathology; D008297:Male; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D051267:NF-E2-Related Factor 2 / Q000172:deficiency / Q000235:genetics; D018384:Oxidative Stress; D010105:Oxygenases / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D013997:Time Factors
chemical_list: D001647:Bile Acids and Salts; D015415:Biomarkers; D051267:NF-E2-Related Factor 2; C495636:Nfe2l2 protein, mouse; D012333:RNA, Messenger; D010105:Oxygenases; C020066:dimethylaniline monooxygenase (N-oxide forming); D000410:Alanine Transaminase
keywords: Acetaminophen; Allyl alcohol; Alpha-naphthyl isothiocyanate; Bile duct ligation; Carbon tetrachloride; Flavin-containing monoxygenase-3; Hepatotoxicants; Nrf2; Oxidative stress