Identification and characterization of a putative bile acid-responsive element in cholesterol 7 alpha-hydroxylase gene promoter.

Title

Identification and characterization of a putative bile acid-responsive element in cholesterol 7 alpha-hydroxylase gene promoter.

Creator

Chiang J Y; Stroup D

Publisher

The Journal of biological chemistry

Date

1994
1994-07

Description

Nucleotide sequences of a 7997-base pair SacI fragment spanning 3643 base pairs of the upstream promoter region to exon 4 of the rat cholesterol 7 alpha-hydroxylase gene (CYP7) have been determined. DNase I footprinting and electrophoretic mobility shift assay of the proximal promoter from nucleotides -346 to +36 revealed two protected regions which specifically shifted proteins in rat liver nuclear extracts. Footprint A (nucleotides -81 to -35) contained a cluster of overlapping sequence motifs of TGT3, steroid/thyroid hormone response elements (7 alpha TRE), hepatocyte nuclear factors 1 and 4, and CAAT/enhancer-binding protein alpha and has been shown to confer bile acid repression of the CYP7 gene promoter activity. Footprint B (nucleotides -148 to -129) contained a sequence motif HNF4. When footprint A (-101 to -49) or 7 alpha TRE (-73 to -55) sequence was linked upstream to a heterologous SV40 promoter/luciferase plasmid and transiently transfected into HepG2 cells, taurodeoxycholate suppressed the SV40 promoter activity. Electrophoretic mobility shift assays revealed that one or two bands shifted by the 7 alpha TRE or by a direct repeat sequence in 7 alpha TRE were absent when liver nuclear extracts of deoxycholic acid-treated rats were used. Similar gel shift patterns were also observed when human 7 alpha TRE or human liver nuclear extracts were used. The rat direct repeat sequence interacted with two polypeptides (M(r) = 57,000 and 116,000) in both rat and human liver nuclear extracts. These results suggest that hydrophobic bile acids may suppress the CYP7 gene expression by binding to a bile acid receptor which interacts with and prevents the binding of liver nuclear protein(s) to a bile acid-responsive element and that the core of bile acid-responsive element is a direct repeat.

Subject

Humans; Animals; Rats; Gene Expression Regulation; Base Sequence; Bile Acids and Salts/*metabolism; Cholesterol 7-alpha-Hydroxylase/*genetics/metabolism; Molecular Sequence Data; Recombinant Fusion Proteins/genetics/metabolism; Luciferases/genetics; DNA-Binding Proteins/metabolism; Deoxyribonuclease I; Nuclear Proteins/metabolism; Oligodeoxyribonucleotides; Thyroid Hormones/genetics; Sprague-Dawley; Genetic; Enzymologic; Cloning; Molecular; *Promoter Regions; Antigens; Polyomavirus Transforming/genetics

Rights

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

Pages

17502–17507

Issue

26

Volume

269

Citation

Chiang J Y; Stroup D, “Identification and characterization of a putative bile acid-responsive element in cholesterol 7 alpha-hydroxylase gene promoter.,” NEOMED Bibliography Database, accessed May 14, 2021, https://neomed.omeka.net/items/show/5346.

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