Regulatory xenobiotic responsive elements in the distal 5'-flanking region of the mouse Cyp1a2 gene required for transcriptional activation by 3-methylcholanthrene and 2,3,7,8-tetrachlorodibenzo-p-dioxin.
We examined the xenobiotic responsive element (XRE) responsible for induction of the mouse Cyp1a2 gene by 3-methylcholanthrene (3MC) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) using a reporter gene assay in mouse hepatocytes in primary culture. Although, the 5'-flanking region up to -9.5 kilobase pairs did not show a significant increase in transcriptional activity after treatment with 3MC or TCDD, a further distal 5'-flanking region from -13,958 to -12,520 containing 12 putative XREs (5'-GCGTG-3') demonstrated distinctive transcriptional activity after treatment with 3MC or TCDD. When a mutation was introduced into XRE14 at -12,972, the activation was decreased, and concurrent mutations in XRE14, XRE13, and XRE15 completely abolished it. However, mutations in XRE13, XRE15, XRE16, or XRE17 did not affect the inducible transcriptional activation of the mouse Cyp1a2 gene. These results suggest that XRE14 is important and that XRE13 at -12,897 and/or XRE15 at -13,061 are cooperative to the inducible transcriptional activation of the mouse Cyp1a2 gene by ligands of the aryl hydrocarbon receptor.
Kawasaki
Yuki
Y
Department of Toxicology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama, Japan. yukikawa@pha.u-toyama.ac.jp
Sakuma
Tsutomu
T
Goto
Yuma
Y
Nemoto
Nobuo
N
D024506:5' Flanking Region / Q000235:genetics*; D000818:Animals; D002478:Cells, Cultured; D019388:Cytochrome P-450 CYP1A2 / Q000235:genetics*; D017930:Genes, Reporter; D022781:Hepatocytes / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D008156:Luciferases / Q000235:genetics; D008297:Male; D008748:Methylcholanthrene / Q000633:toxicity*; D051379:Mice; D008810:Mice, Inbred C57BL; D000072317:Polychlorinated Dibenzodioxins / Q000633:toxicity*; D050436:Regulatory Elements, Transcriptional / Q000235:genetics*; D015533:Transcriptional Activation / Q000187:drug effects*; D014162:Transfection; D015262:Xenobiotics / Q000633:toxicity*
D000072317:Polychlorinated Dibenzodioxins; D015262:Xenobiotics; D008748:Methylcholanthrene; D008156:Luciferases; D019388:Cytochrome P-450 CYP1A2