Repression of cAMP-induced expression of the mouse P450 17α- hydroxylase/C17-20 lyase gene (Cyp17) by androgens

María Burgos-Trinidad, Geri L. Youngblood, Medardo R. Maroto, Arno Scheller, Diane M. Robins, Anita H. Payne

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Abstract

In primary cultures of mouse Leydig cells, testosterone represses the cAMP-induced de novo synthesis of P450 17α-hydroxylase/C17-20 lyase (P450c17) protein and the accumulation of P450c17 mRNA, via an androgen receptor (AR)-mediated mechanism. To examine the mechanism by which androgens repress the cAMP-induced expression of the mouse Cyp17 gene, constructs containing 5'-flanking sequences of the mouse Cyp17 linked to the chloramphenicol acetyltransferase (CAT) reporter gene were cotransfected into MA-10 tumor Leydig cells with a mouse AR expression plasmid. In the presence of dihydrotestosterone, the cAMP-induced expression of a reporter construct containing -1021 bp of Cyp17 promoter sequences was repressed. In contrast, no repression by dihydrotestosterone was observed when the -1021 bp Cyp17- CAT construct was cotransfected with a human AR expression plasmid missing the second zinc finger of the DNA-binding domain, indicating that DNA binding is involved in AR-mediated repression of Cyp17 expression. Analysis of deletions of the -1021 bp fragment demonstrated that -346 bp of 5'-flanking region of the mouse Cyp17 promoter are sufficient to confer androgen repression of the cAMP-induced expression of Cyp17. Deoxyribonuclease I footprinting analysis indicated that the AR interacts with sequences between -330 and -278 bp of the Cyp17 promoter. This region overlaps with the previously identified cAMP-responsive region located between -346 and -245 bp of the Cyp17 promoter. These results suggest that AR-mediated repression involves binding of the AR to sequences in the cAMP-responsive region of the Cyp17 promoter, possibly interfering with the binding of the protein(s) that mediate cAMP induction of Cyp17.

Original languageEnglish (US)
Pages (from-to)87-96
Number of pages10
JournalMolecular Endocrinology
Volume11
Issue number1
DOIs
StatePublished - Jan 18 1997

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ASJC Scopus subject areas

  • Molecular Biology
  • Endocrinology

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