title: Cloning and expression of the rat adrenal cytochrome P-450 11B3 (CYP11B3) enzyme cDNA: preferential 18-hydroxylation over 11 beta-hydroxylation of DOC.
abstract: The biosynthesis of glucocorticoids and mineralocorticoids in the rat adrenal cortex requires the action of two different cytochrome P450 11 beta-hydroxylases, CYP11B1 and CYP11B2, which are distributed in the zona fasciculata and glomerulosa, respectively. The existence of another cytochrome P450-11 beta gene, CYP11B3, was recently reported. Although CYP11B3 has similar gene structure and great homology to the CYP11B1 and -B2 genes, the CYP11B3 mRNA was not originally detected by reverse transcription-polymerase chain reaction (RT-PCR) and has only recently been cloned and detected from neonatal rat adrenals. Herein we demonstrate RT-PCR detection of CYP11B3 mRNA expressed in adult rat adrenal and brain tissues. The whole coding region of the CYP11B3 enzyme cDNA was cloned and sequenced. When transiently expressed in COS-7 cells the CYP11B3 converted deoxycorticosterone (DOC) to corticosterone and 18-hydroxydeoxycorticosterone, but not to 18-hydroxycorticosterone or aldosterone. It produced more 18-OH-DOC than corticosterone. A single mutation in CYP11B3 in which Gly-59 was replaced by Ser, reduced the enzymatic activity 5-6-fold. Furthermore, CYP11B3 mRNA expression is greater in neonatal, compared to adult rat adrenal glands.
authors.affiliation: Division of Endocrinology and Metabolism, University of Missouri-Columbia, USA.
authors.forename: M Y
authors.initials: MY
authors.lastname: Zhou
authors.forename: E P
authors.initials: EP
authors.lastname: Gomez-Sanchez
authors.forename: M F
authors.initials: MF
authors.lastname: Foecking
authors.forename: C E
authors.initials: CE
authors.lastname: Gomez-Sanchez
mesh_terms: D000311:Adrenal Glands / Q000201:enzymology; D000595:Amino Acid Sequence; D000818:Animals; D000831:Animals, Newborn; D001483:Base Sequence; D001921:Brain / Q000201:enzymology; D002460:Cell Line; D003001:Cloning, Molecular; D019405:Cytochrome P-450 CYP11B2; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics* / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics*; D003900:Desoxycorticosterone / Q000737:chemistry / Q000378:metabolism; D015870:Gene Expression; D006900:Hydroxylation; D008969:Molecular Sequence Data; D017354:Point Mutation; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D013252:Steroid 11-beta-Hydroxylase / Q000235:genetics* / Q000378:metabolism; D014162:Transfection
chemical_list: D017931:DNA Primers; D018076:DNA, Complementary; D012333:RNA, Messenger; D003900:Desoxycorticosterone; D003577:Cytochrome P-450 Enzyme System; D019405:Cytochrome P-450 CYP11B2; D013252:Steroid 11-beta-Hydroxylase