Characterization of a cDNA clone for mouse phenobarbital-inducible cytochrome P-450b.
p40, a mouse 1040-nucleotide cDNA clone encoding a form of phenobarbital-inducible cytochrome P-450b, was selected by probing a cDNA library derived from phenobarbital-treated DBA/2N mouse liver with a rat 1830-nucleotide cDNA probe complementary to P-450b mRNA. When rat and mouse liver poly(A)+-enriched total RNAs are probed with p40, control rat P-450b mRNA levels are at least three times as much as control mouse P-450b levels. A 15-fold increase in rat 19S mRNA and only a 3-fold increase in the corresponding mouse 19S mRNA are found following phenobarbital treatment. An intranuclear 4800-nucleotide mRNA precursor is also detectable during the induction process with phenobarbital. Clofibrate, a hypolipidemic drug, is a potent inducer of P-450. There is no cross-hybridization between clofibrate-induced mRNA and either mouse P-450b cDNA or mouse P1-450 cDNA clones. At the level of hybridization stringency used for the Northern analysis, there is no cross-hybridization between phenobarbital-induced mouse or rat P-450b and the P1-450 cDNA probe or between 3-methylcholanthrene-induced mouse or rat P1-450 and the P-450b cDNA probe. These data indicate that the induction process by clofibrate involves activation of P-450 gene(s) not present in the multigene families inducible by either phenobarbital or polycyclic aromatic compounds, i.e., at least three sets of P-450 genes operate independently of one another. Two previously reported cDNA clones of phenobarbital-inducible rat P-450, R17 (P- 450e ) and pcP- 450pb4 (P-450b), were compared with mouse p40.(ABSTRACT TRUNCATED AT 250 WORDS)
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002994:Clofibrate / Q000494:pharmacology; D003001:Cloning, Molecular; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis / Q000235:genetics*; D004247:DNA / Q000235:genetics*; D004790:Enzyme Induction / Q000187:drug effects; D008748:Methylcholanthrene / Q000494:pharmacology; D051379:Mice; D010634:Phenobarbital / Q000494:pharmacology; D011817:Rabbits; D051381:Rats; D013045:Species Specificity
D008748:Methylcholanthrene; D004247:DNA; D003577:Cytochrome P-450 Enzyme System; D002994:Clofibrate; D010634:Phenobarbital