title: Calcium regulates human CYP11B2 transcription.
abstract: The CYP11B2 gene encodes aldosterone synthase, a cytochrome P450 (P450aldo) expressed in high levels in the adrenal zona glomerulosa. While the primary physiologic regulators of aldosterone production are circulating angiotensin II (Ang II) and potassium (K+) the action of these agents on CYP11B2 gene transcription have not been examined. Because these factors increase intracellular calcium we have hypothesized that calcium signaling pathways are one mechanism controlling CYP11B2 transcription. Previously we demonstrated that increases in intracellular calcium increase P450aldo mRNA. Herein, we analyzed the role of calcium in the expression of the human CYP11B2 gene using transient transfection of a luciferase reporter construct containing 2017 bp of human CYP11B2 5'flanking DNA in mouse Y-1 and human H295R adrenocortical cell lines. When transfected into Y-1 cells, reporter gene expression was increased following treatment with ACTH or forskolin, but not with Ang II, the L-type calcium channel agonist BAYK8644, or ionomycin. In H295R cells, however, reporter gene expression was increased following treatment with Ang II, K+, BAYK8644 ionomycin or dibutyryl cAMP (Bu2cAMP). Activation of protein kinase C with TPA did not alter reporter gene expression in either cell line. These data demonstrate that both calcium and cAMP signaling pathways regulate human CYP11B2 gene expression. In addition, the H295R adrenal cell line appears to be an appropriate model to study regulation of CYP11B2 by calcium.
authors.affiliation: Division of Reproductive Endocrinology, University of Texas, Southwestern Medical School, Dallas 75235-9032, USA.
authors.forename: C D
authors.initials: CD
authors.lastname: Clyne
authors.forename: P C
authors.initials: PC
authors.lastname: White
authors.forename: W E
authors.initials: WE
authors.lastname: Rainey
mesh_terms: D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000302:Adrenal Cortex / Q000201:enzymology; D000324:Adrenocorticotropic Hormone / Q000494:pharmacology; D000450:Aldosterone / Q000096:biosynthesis; D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002460:Cell Line; D005576:Colforsin / Q000494:pharmacology; D019405:Cytochrome P-450 CYP11B2 / Q000235:genetics*; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D008156:Luciferases / Q000235:genetics; D051379:Mice; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction; D014158:Transcription, Genetic / Q000187:drug effects*; D014162:Transfection
chemical_list: D012333:RNA, Messenger; D005576:Colforsin; D015124:8-Bromo Cyclic Adenosine Monophosphate; D000450:Aldosterone; D000324:Adrenocorticotropic Hormone; D008156:Luciferases; D019405:Cytochrome P-450 CYP11B2; D002118:Calcium