Transcriptional regulation of the human cholesterol 7. alpha. -hydroxylase gene

Journal Article · Tue Mar 10 04:00:00 EST 1992 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00124a014· OSTI ID:5640389

Molowa, D T; Cimis, G M; Tan, C P ^[1]; Chen, W S ^[2]

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1. Merck Sharp and Dohme Research Labs., Rahway, NJ (United States)
2. Rockefeller Univ., New York, NY (United States)

As an initial step toward understanding the transcriptional regulation of cholesterol 7{alpha}-hydroxylase (CYP7) in man, the authors isolated and functionally characterized the 5{prime}-flanking region of the human CYP7 gene. The nucleotide sequences of the first exon and 1.6 kb preceding the exon were determined and found to contain a TATA box at position {minus}30, a modified CAAT box at position {minus}92, three potential hepatocyte nuclear factor 3 (HNF-3) recognition sites at nucleotides {minus}316, {minus}288, and {minus}255, respectively, and a modified sterol response element at position {minus}271. DNA sequences containing 1.3 kb of the 5{prime}-flanking region and 29 nucleotides of the first exon were linked to the chloramphenicol acetyltransferase gene and transiently transfected into several cell lines. Promoter activity was very strong in the human hepatoma cell line HepG2 but absent in cells of nonhepatic origin. Mutational analysis of the promoter identified several regions that function in the transcriptional regulation of CYP7. Introduction of a fragment containing the region from {minus}432 to {minus}220 upstream of a heterologous promoter, in either orientation, resulted in a tremendous stimulation of activity in HepG2 cells. DNase I footprint analysis identified three regions within this fragment which were protected from digestion. The overexpression of HNF-3 in HepG2 cells resulted in a 4-fold stimulation of CYP7 transcriptional activity. They suggest that the region between {minus}432 and {minus}220 functions as a cell-specific enhancer whose activity is controlled, in part, by HNF-3.

• OSTI ID: 5640389
• Journal Information: Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 31:9; ISSN 0006-2960; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AMINO ACID SEQUENCE
ANIMALS
CHOLESTEROL
DNA SEQUENCING
ENZYMES
GENE REGULATION
GENE REPRESSORS
GENES
HYDROXY COMPOUNDS
HYDROXYLASES
MAMMALS
MAN
MOLECULAR STRUCTURE
ORGANIC COMPOUNDS
OXIDOREDUCTASES
PRIMATES
PROTEINS
STEROIDS
STEROLS
STRUCTURAL CHEMICAL ANALYSIS
TRANSCRIPTION
VERTEBRATES