Expression profiles of SF-1, DAX1, and CYP17 in the human fetal adrenal gland: potential interactions in gene regulation.
Cytochrome P450 17alpha-hydroxylase/17-20 lyase (P450(C17)) is a critical branchpoint enzyme for steroid hormone biosynthesis. During human gestation, P450(C17) is required for the production of dehydroepiandrostenedione sulfate by the fetal adrenal cortex and for testicular production of androgens that mediate male sexual differentiation. In this study, we investigate the regulation of the human CYP17 gene by two orphan nuclear receptors, steroidogenic factor 1 (SF-1) and DAX1. In human embryos, SF-1 and DAX1 are expressed throughout the developing adrenal cortex from its inception at 33 days post conception (dpc). In contrast, P450(C17) expression, which commences between 41 and 44 dpc, is limited to the fetal zone. The 5'-flanking region of the human CYP17 gene contains three functional SF-1 elements that collectively mediate a > or =25-fold induction of promoter activity by SF-1. In constructs containing all three functional SF-1 elements, DAX1 inhibited this activation by > or =55%. In the presence of only one or two SF-1 elements, DAX1 inhibition was lost even though SF-1 transactivation persisted. These data suggest that efficient repression of SF-1-mediated activation of the human CYP17 gene by DAX1 requires multiple SF-1 elements. Opposing effects of SF-1 and DAX1 may fine tune the differential responses of various SF-1 target genes in different endocrine tissues.
Hanley
N A
NA
Department of Internal Medicine & Pharmacology, University of Texas Southwestern Medical Center Dallas, Texas 75390-8857, USA.
Rainey
W E
WE
Wilson
D I
DI
Ball
S G
SG
Parker
K L
KL
D000311:Adrenal Glands / Q000196:embryology* / Q000378:metabolism*; D001665:Binding Sites; D002460:Cell Line; D057137:DAX-1 Orphan Nuclear Receptor; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005260:Female; D051717:Fushi Tarazu Transcription Factors; D005786:Gene Expression Regulation / Q000187:drug effects; D005865:Gestational Age; D018398:Homeodomain Proteins; D006801:Humans; D008297:Male; D016296:Mutagenesis; D018160:Receptors, Cytoplasmic and Nuclear; D018168:Receptors, Retinoic Acid / Q000737:chemistry / Q000235:genetics*; D011994:Recombinant Proteins / Q000378:metabolism / Q000494:pharmacology; D012097:Repressor Proteins; D013254:Steroid 17-alpha-Hydroxylase / Q000235:genetics*; D054339:Steroidogenic Factor 1; D013329:Structure-Activity Relationship; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics* / Q000494:pharmacology; D014158:Transcription, Genetic / Q000187:drug effects; D014162:Transfection
D057137:DAX-1 Orphan Nuclear Receptor; D004268:DNA-Binding Proteins; D051717:Fushi Tarazu Transcription Factors; D018398:Homeodomain Proteins; C539965:NR0B1 protein, human; C515057:NR5A1 protein, human; D018160:Receptors, Cytoplasmic and Nuclear; D018168:Receptors, Retinoic Acid; D011994:Recombinant Proteins; D012097:Repressor Proteins; D054339:Steroidogenic Factor 1; D014157:Transcription Factors; D013254:Steroid 17-alpha-Hydroxylase