Hormonal regulation of the cholesterol 7 alpha-hydroxylase gene (CYP7).

Hormonal regulation of the cholesterol 7 alpha-hydroxylase gene (CYP7).

Crestani M; Stroup D; Chiang J Y

Journal of lipid research

1995

1995-11

The transcriptional regulation of the rat cholesterol 7 alpha-hydroxylase gene (CYP7) by hormones and signal transduction pathways was studied by transient transfection assay of the promoter activity. HepG2 cells were transfected with deletion mutants of the CYP7 upstream region linked to the luciferase reporter gene. The transcription of CYP7/luciferase chimeric genes was higher in confluent than in subconfluent cultures of HepG2 cells. Glucocorticoid receptors, in the presence of dexamethasone, up-regulated the CYP7 gene through two regions located between -3262 and -2803, and between -344 and -222, respectively. Thyroid hormones did not have any effect on the promoter activity. Insulin inhibited the promoter activity through sequences located between -344 and -222, and abolished the stimulation by dexamethasone. Hence, the insulin effect was dominant over that of glucocorticoids. Treatment of transfected HepG2 cells with phorbol

Animals; Rats; Gene Expression Regulation; Cell Count; Transfection; Base Sequence; Molecular Sequence Data; Phorbol Esters/pharmacology; Cholesterol 7-alpha-Hydroxylase/*genetics; Luciferases/genetics; Cyclic AMP/pharmacology; Hormones/*pharmacology; Second Messenger Systems/physiology; Cultured; Genetic; Tumor Cells; Cloning; Molecular; *Promoter Regions; *Transcription; Enzymologic/*physiology

Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).

2419–2432

11

36