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EMBO J. 1992 Jun;11(6):2241-6.

Interference between pathway-specific transcription factors: glucocorticoids antagonize phorbol ester-induced AP-1 activity without altering AP-1 site occupation in vivo.

Author information

1
Kernforschungszentrum Karlsruhe, Institut für Genetik und Toxikologie, Germany.

Abstract

Phorbol esters stimulate and glucocorticoid hormones down-regulate a variety of promoters such as that of the collagenase gene through the transcription factor AP-1 (Fos/Jun). We now show by genomic footprinting of the collagenase promoter that phorbol ester treatment of cells results in the binding of AP-1 to its cognate DNA binding site in vivo. The DNA-protein contacts obtained in living cells are also found in vitro using cloned DNA and purified AP-1. Although in vitro synthesized glucocorticoid receptor can disturb the DNA binding of Jun homodimers, it does not interfere with the binding of Fos-Jun heterodimers or of purified AP-1 in vitro. Consistently, fully inhibitory doses of glucocorticoid hormone cause no change in apparent occupation of the AP-1 binding site in vivo. The hormone receptor acts without itself binding to DNA.

PMID:
1318196
PMCID:
PMC556691
[Indexed for MEDLINE]
Free PMC Article

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