Identification and characterization of a novel tissue-specific transcriptional activating element in the 5'-flanking region of the CYP2A3 gene predominantly expressed in rat olfactory mucosa.
CYP2A3 is expressed preferentially in rat olfactory mucosa and is believed to play important roles in maintaining cellular homeostasis in the chemosensory tissue. DNase I footprinting analysis revealed a single protected region in the proximal promoter of the CYP2A3 gene with nuclear extracts from olfactory mucosa, but not from liver, lung, kidney, or brain. The core sequence of the binding site, named the nasal predominant transcriptional activating (NPTA) element, is similar to that of nuclear factor 1, but it interacted with unique proteins detected only in the olfactory mucosa in electrophoretic mobility shift assays or on Southwestern blots. The NPTA element is conserved in rat CYP2A3, mouse Cyp2a5, and human CYP2A6 genes and was found to be essential for transcriptional activity of the CYP2A3 promoter in in vitro transcription assays. NPTA-binding proteins were detectable at day 1 and were much more abundant at day 8 than at day 60 after birth. Furthermore, their levels decreased dramatically during chemically induced degeneration of the olfactory epithelium, paralleling the disappearance of CYP2A3 protein, and rebounded to higher than pretreatment levels during recovery. Thus, we have identified a novel transcriptional activation element potentially responsible for the olfactory mucosa-predominant expression of the CYP2A3 gene in rats and orthologous genes in mice and humans.
Wadsworth Center, New York State Department of Health and the Department of Environmental Health and Toxicology, School of Public Health, State University of New York, Albany, New York 12201-0509, USA.
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Zhang
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Ding
D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases; D001483:Base Sequence; D001665:Binding Sites; D001667:Binding, Competitive; D065637:Cytochrome P-450 CYP2A6; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis / Q000235:genetics*; D000072467:Cytochrome P450 Family 2; D018983:DNA Footprinting; D004268:DNA-Binding Proteins / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D006899:Mixed Function Oxygenases / Q000096:biosynthesis / Q000235:genetics*; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism; D009831:Olfactory Mucosa; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D051381:Rats; D017208:Rats, Wistar; D014018:Tissue Distribution
D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; C585519:Cyp2a3 protein, rat; D001189:Aryl Hydrocarbon Hydroxylases; C585710:CYP2A6 protein, human; C585520:Cyp2a5 protein, mouse; D065637:Cytochrome P-450 CYP2A6; D000072467:Cytochrome P450 Family 2