The opposing effects of retinoic acid and phorbol esters converge to a common response element in the promoter of the rat cholesterol 7 alpha-hydroxylase gene (CYP7A).

The opposing effects of retinoic acid and phorbol esters converge to a common response element in the promoter of the rat cholesterol 7 alpha-hydroxylase gene (CYP7A).

Crestani M; Sadeghpour A; Stroup D; Galli G; Chiang J Y

Biochemical and biophysical research communications

1996

1996-08

The activity of the rat CYP7A/luciferase reporter gene was increased five-fold by all-trans retinoic acid (atRA) or 9-cis retinoic acid (9cRA) in transient transfection assay in HepG2 cells. Cotransfection with retinoid X receptor (RXR) stimulated the promoter activity in the absence of ligand, however, addition of atRA inhibited the transcriptional activity. Cotransfection with retinoic acid receptor (RAR) did not have much effect on CYP7A promoter activity. The CYP7A promoter, when linked upstream to the SV40/ luciferase reporter gene, strongly repressed the phorbol 12-myristate 13-acetate (PMA)-stimulated SV40/ luciferase reporter gene activity. The regions conferring the effects of RA and PMA were mapped to nt-176/ -117 and nt-148/-129, respectively. Several direct repeats of hormone response element (AGTTCA) in this region are required for RA response.

*Promoter Regions; Animals; Base Sequence; Cell Line; Cholesterol 7-alpha-Hydroxylase/*genetics/metabolism; DNA Primers; Genetic; Molecular Sequence Data; Mutagenesis; Rats; Signal Transduction; Tetradecanoylphorbol Acetate/*pharmacology; Tretinoin/*pharmacology

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