The transcriptional activation of the human copper/zinc superoxide dismutase gene by 2,3,7,8-tetrachlorodibenzo-p-dioxin through two different regulator sites, the antioxidant responsive element and xenobiotic responsive element.
Cu/Zn superoxide dismutase (SOD1) catalyzes the dismutation of superoxide radicals produced during biological oxidations and environmental stress. The most toxic dioxin, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), induces SOD1 in human liver cells. Deletion analyses showed that the promoter region between -400 and -239 was responsible for the induction, in which two different characteristic regulatory elements, the antioxidant responsive element (ARE) and xenobiotic responsive element (XRE), are located. When the cells transfected with the plasmid containing those two cis-elements, the transactivation of SOD1 promoter was about 4-fold by TCDD, whereas mutation either on the ARE or XRE elevated the promoter activity by about 2-fold. Functional analyses of these two elements by deletion, mutation in the natural context, heterologous promoter assay, and gel mobility shift assay supported the notion that the activation of the SOD1 promoter was induced by TCDD through these two regulatory elements ARE and XRE. These results alongside our previous data indicate that the induction of SOD1 in response to TCDD is mediated by either Nrf2 protein or Ah receptor protein through ARE and XRE, respectively. These results also imply that the SOD1 can be induced by dioxin either in combination with or independently of these two regulatory elements to effectively defend cells from oxidative stress.
Park
Eun Young
EY
School of Biological Sciences, Seoul National University, Seoul, Korea.
Rho
Hyune Mo
HM
D000975:Antioxidants / Q000494:pharmacology*; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D004790:Enzyme Induction / Q000187:drug effects; D006801:Humans; D009154:Mutation / Q000235:genetics; D051267:NF-E2-Related Factor 2; D018384:Oxidative Stress; D000072317:Polychlorinated Dibenzodioxins / Q000494:pharmacology*; D011401:Promoter Regions, Genetic / Q000235:genetics; D020218:Response Elements / Q000235:genetics*; D013482:Superoxide Dismutase / Q000235:genetics*; D015534:Trans-Activators / Q000378:metabolism; D015533:Transcriptional Activation / Q000187:drug effects*; D014407:Tumor Cells, Cultured; D015262:Xenobiotics / Q000494:pharmacology*
D000975:Antioxidants; D004268:DNA-Binding Proteins; D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; D000072317:Polychlorinated Dibenzodioxins; D015534:Trans-Activators; D015262:Xenobiotics; D004247:DNA; D013482:Superoxide Dismutase