title: Regulation of two members of the steroid-inducible cytochrome P450 subfamily (3A) in rats.
abstract: Monoclonal antibodies have been successfully isolated which are isozyme-specific for cytochrome P450p (3A1) or P4501 (3A2), two members of the steroid-inducible cytochrome P450 subfamily exhibiting 89% amino acid sequence homology, and these antibodies show less than 5% cross-reaction with 11 other cytochromes P450 (P450a-P450k). A library of 28 purified monoclonal antibodies was established and characterized as to epitope specificity. Appropriate antibodies were selected and utilized to investigate the regulation of expressed cytochrome P450p and P4501 proteins as a function of age, sex, and treatment of rats with various inducing agents. Cytochrome P450p is not detectable in hepatic microsomes from untreated immature or adult male and female rats. Following dexamethasone treatment, expression of cytochrome P450p is observed in all groups with the levels reaching 30-37% of total microsomal cytochrome P450. Administration of other inducers such as pregnenolone 16 alpha-carbonitrile also yield enhanced levels of cytochrome P450p. Measurable amounts of constitutive cytochrome P4501 were detected in hepatic microsomes from immature and adult males as well as immature females but not in adult females. Cytochrome P4501 expression is inducible by dexamethasone in immature rats of both sexes and adult males, although dexamethasone is more effective as an inducer of cytochrome P450p than cytochrome P4501. Hence, not only is cytochrome P4501 protein expressed in immature animals of both sexes, it is also inducible in both sexes. These studies show that constitutive expression and induction of steroid-inducible cytochrome P450s may vary as a function of age.
authors.affiliation: Department of Chemical Biology, College of Pharmacy, Rutgers University, Piscataway, New Jersey 08854-0789.
authors.forename: K O
authors.initials: KO
authors.lastname: Cooper
authors.forename: L M
authors.initials: LM
authors.lastname: Reik
authors.forename: Z
authors.initials: Z
authors.lastname: Jayyosi
authors.forename: S
authors.initials: S
authors.lastname: Bandiera
authors.forename: M
authors.initials: M
authors.lastname: Kelley
authors.forename: D E
authors.initials: DE
authors.lastname: Ryan
authors.forename: R
authors.initials: R
authors.lastname: Daniel
authors.forename: S A
authors.initials: SA
authors.lastname: McCluskey
authors.forename: W
authors.initials: W
authors.lastname: Levin
authors.forename: P E
authors.initials: PE
authors.lastname: Thomas
mesh_terms: D000367:Age Factors; D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal; D000918:Antibody Specificity; D019392:Cytochrome P-450 CYP2E1; D051544:Cytochrome P-450 CYP3A; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology; D004790:Enzyme Induction; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D015151:Immunoblotting; D007527:Isoenzymes / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology; D008297:Male; D006899:Mixed Function Oxygenases / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000096:biosynthesis*; D051381:Rats; D011919:Rats, Inbred Strains; D017421:Sequence Analysis; D012737:Sex Factors; D013256:Steroids
chemical_list: D000911:Antibodies, Monoclonal; D000939:Epitopes; D007527:Isoenzymes; D012333:RNA, Messenger; D013256:Steroids; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; D019392:Cytochrome P-450 CYP2E1; C104464:CYP3A protein, human; D051544:Cytochrome P-450 CYP3A