Expression of the chloramphenicol acetyltransferase (CAT) reporter gene by the murine Cyp1a-2 (cytochrome P3(450)) promoter in hepatoma cell cultures.
In C57BL/6 mouse liver, both murine Cypla-1 (cytochrome P1(450] and Cypla-2 (P3(450] genes are inducible by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD; dioxin), and Cypla-2 is constitutively expressed at high levels. Although the Cypla-1 gene is constitutively expressed and TCDD-inducible in mouse hepatoma Hepa-1 cell cultures, Cypla-2 gene expression is absent in these cultures. We show here that the 5' flanking region of Cyp1a-2 from - 1843 to +52 (base pairs relative to the Transcription initiation site) linked to the chloramphenicol acetyltransferase (CAT) reporter gene in stable Hepa-1 transformants produces no basal or TCDD- or cycloheximide-inducible CAT activity. On the other hand, the Cyp1a-2 promoter from -63 to +52 driving the CAT gene is inducible by cycloheximide. A chimeric plasmid containing the Cyp1a-1 TCDD-responsive enhancer (-1646 to -245) ligated to a Cyp1a-2 promoter region (-129 to +52) supports TCDD-inducible CAT expression in Hepa-1 cells and in rat 7777 cells. These data suggest that, although sequences between - 1843 and +52 +52 are not sufficient for Cyp1a-2 gene expression, the murine Cyp1a-2 promoter is functional in cell cultures.
Owens
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RA
Laboratory of Developmental Pharmacology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892.
Nebert
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DW
D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000201:enzymology / Q000235:genetics*; D002471:Cell Transformation, Neoplastic; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics*; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis / Q000235:genetics*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D051379:Mice; D008810:Mice, Inbred C57BL / Q000235:genetics*; D010957:Plasmids; D011401:Promoter Regions, Genetic; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D003577:Cytochrome P-450 Enzyme System; D015500:Chloramphenicol O-Acetyltransferase; D013755:Tetradecanoylphorbol Acetate