Transcriptional regulation by HNF-4 of the steroid 15alpha-hydroxylase P450 (Cyp2a-4) gene in mouse liver.
The mouse P450 gene Cyp2a-4 encodes the hepatic steroid 15apha-hydroxylase. We have defined in the 5'-flanking sequence of Cyp2a-4 gene, a composite regulatory element (-61AGACCAAAGTCCGGCCTTC-42) which contains a potential CpG methylation site at position -50. Gel-shift assays indicate that this element consists of overlapped binding sites for a hepatocyte-enriched transcription factor HNF-4 and a Sp1-like protein. Moreover, transcription of the Cyp2a-4 gene is activated by coexpression of HNF-4 in HepG2 cells. A mutation (C at -50 to A) abolishes the binding of HNF-4 to the element as well as the transcriptional activation by HNF-4. The methylated C at position -50, however, does not affect HNF-4 binding. Neither the mutation nor the methylation at position -50 affect the binding of Sp1-like protein to the element. It appears, therefore, that HNF-4 activates the hepatic transcription of Cyp2a-4 gene through its direct binding to the regulatory element regardless of the methylation at position -50.
Yokomori
N
N
Laboratory of Reproductive and Developmental Toxicology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA.
Nishio
K
K
Aida
K
K
Negishi
M
M
D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics* / Q000378:metabolism; D018983:DNA Footprinting; D019175:DNA Methylation; D004268:DNA-Binding Proteins; D005260:Female; D017930:Genes, Reporter; D051557:Hepatocyte Nuclear Factor 4; D008099:Liver / Q000201:enzymology*; D008297:Male; D051379:Mice; D009154:Mutation; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics*; D013250:Steroid Hydroxylases / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation
D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D004268:DNA-Binding Proteins; D051557:Hepatocyte Nuclear Factor 4; D010750:Phosphoproteins; C501970:Tcfl4 protein, mouse; D014157:Transcription Factors; D003577:Cytochrome P-450 Enzyme System; D013250:Steroid Hydroxylases; D001189:Aryl Hydrocarbon Hydroxylases; C050356:steroid 15-alpha-hydroxylase