Transcriptional regulation of human 11beta-hydroxylase (hCYP11B1).
Steroid 11beta-hydroxylase is a mitochondrial enzyme that catalyzes the conversion of deoxycortisol to cortisol. The gene encoding human 11beta-hydroxylase (hCYP11B1) is expressed in the adrenal cortex under the control of circulating levels of ACTH. The current study was undertaken to define the cis-regulatory elements and transacting factors that regulate hCYP11B1 transcription. The hCYP11B1 5'-flanking DNA was studied using transient transfection of luciferase reporter constructs in NCI-H295R human adrenocortical cells. A cAMP analogue ((Bu)2cAMP) increased expression of a construct containing -1102 bp of hCYP11B1 5'-flanking DNA (pB1-1102). An element at position -71/-64 (TGACGTGA, previously termed Ad1) resembling a consensus cAMP response element (CRE) was required for maximal induction by cAMP. The Ad1 element bound several transcriptional factors in electrophoretic mobility shift assays, including CRE-binding protein, activating transcription factor-1 (ATF-1), and ATF-2, but only the ATF-2 complex migrated similarly to a complex seen using H295R nuclear extract. In addition, Western analysis of H295R and adrenal lysates demonstrated expression of high levels of ATF-2 and ATF-1. CRE-binding protein levels varied among the strains of H295R cells tested. Transcription of CYP11B1 also appeared to be regulated by steroidogenic factor-1 (SF-1). Luciferase reporter gene activity was increased after cotransfection with expression vectors containing SF-1. An element in hCYP11B1 at positions 242/-234 (CCAAGGCTC), previously termed Ad4, was required for maximal induction by SF-1 and was found to bind SF-1 in electrophoretic mobility shift assays. The key role for SF-1 in hCYP11B1 transcription is in contrast to its lack of an effect on expression of the hCYP11B2 (aldosterone synthase) isozyme. The differential effects of SF-1 on transcription of hCYP11B1 and hCYP11B2 may be one of the mechanisms controlling differential expression of these isozymes within the zonae fasciculata and glomerulosa of the human adrenal cortex.
Wang
X L
XL
Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas 75390-9032, USA.
Bassett
M
M
Zhang
Y
Y
Yin
S
S
Clyne
C
C
White
P C
PC
Rainey
W E
WE
D000311:Adrenal Glands / Q000166:cytology / Q000378:metabolism; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000502:physiology; D051717:Fushi Tarazu Transcription Factors; D017353:Gene Deletion; D018398:Homeodomain Proteins; D006801:Humans; D011401:Promoter Regions, Genetic / Q000235:genetics; D018160:Receptors, Cytoplasmic and Nuclear; D012045:Regulatory Sequences, Nucleic Acid / Q000502:physiology; D013252:Steroid 11-beta-Hydroxylase / Q000235:genetics* / Q000378:metabolism*; D054339:Steroidogenic Factor 1; D014157:Transcription Factors / Q000502:physiology; D014158:Transcription, Genetic / Q000502:physiology*
D004268:DNA-Binding Proteins; D051717:Fushi Tarazu Transcription Factors; D018398:Homeodomain Proteins; C515057:NR5A1 protein, human; D018160:Receptors, Cytoplasmic and Nuclear; D054339:Steroidogenic Factor 1; D014157:Transcription Factors; D013252:Steroid 11-beta-Hydroxylase