title: Genetic differences in induction of cytosol reduced-NAD(P):menadione oxidoreductase and microsomal aryl hydrocarbon hydroxylase in the mouse.
abstract: The stimulation of reduced-NAD(P):menadione oxidoreductase (EC 1.6.99.2) activity in liver cytosol is highly correlated with the stimulation of hepatic microsomal aryl hydrocarbon (benzo[a]pyrene) hydroxylase (EC 1.14.14.2) activity in 3-methylcholanthrene-, beta-naphthoflavone-, phenobarbital-, or pregnenolone-16alpha-carbonitrile-treated inbred C57BL/6N and DBA/2N mice and in eight other inbred strains treated with 3-methylcholanthrene. No oxidoreductase activity is detectable in mouse liver microsomes. Cytochrome c and 2,6-dichlorophenolindophenol are equally good electron acceptors for the oxidoreductase. There is no preferential in vitro inhibition of induced versus control oxidoreductase activities by either alpha-naphthoflavone or metyrapone. In 3-methylcholanthrene-treated F1 and F2 progeny and offspring from backcrosses between the F1 and either C57BL/6N or DBA/2N parent, however, there is not a strict correlation between induced or noninducible aryl hydrocarbon hydroxylase and oxidoreductase activities. 2,3,7,8-Tetrachlorodibenzo-p-dioxin, at doses (80 mug kg-1) sufficiently high to induce the hydroxylase almost as well in DBA/2N as in C57BL/6N mice, induces the oxidoreductase about 3-fold in C57BL/6N and less than 50% in DBA/2N mice. All the data are consistent with an hypothesis that two loci (Ox-1 and Ox-2) regulate oxidoreductase induction by 3-methylcholanthrene, that one of the genes is linked to the Ah locus (with an estimated recombination frequency between 2% and 23%), and that the other gene is not linked to the Ah locus. These experimental data might be useful in the protein activator hypothesis of the Britten-Davidson model for gene regulation.
mesh_terms: D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000096:biosynthesis*; D003433:Crosses, Genetic; D003600:Cytosol / Q000187:drug effects / Q000201:enzymology*; D004790:Enzyme Induction / Q000187:drug effects; D005419:Flavonoids / Q000494:pharmacology; D014644:Genetic Variation; D007700:Kinetics; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D008748:Methylcholanthrene / Q000494:pharmacology; D051379:Mice; D008815:Mice, Inbred Strains; D008862:Microsomes, Liver / Q000187:drug effects / Q000201:enzymology*; D009247:NADH, NADPH Oxidoreductases / Q000096:biosynthesis*; D009570:Nitriles / Q000494:pharmacology; D010634:Phenobarbital / Q000494:pharmacology; D000072317:Polychlorinated Dibenzodioxins / Q000494:pharmacology; D011284:Pregnenolone / Q000031:analogs & derivatives / Q000494:pharmacology; D011808:Quinone Reductases / Q000096:biosynthesis*; D013045:Species Specificity
chemical_list: D005419:Flavonoids; D009570:Nitriles; D000072317:Polychlorinated Dibenzodioxins; D008748:Methylcholanthrene; D011284:Pregnenolone; D001189:Aryl Hydrocarbon Hydroxylases; D009247:NADH, NADPH Oxidoreductases; D011808:Quinone Reductases; D010634:Phenobarbital