Up-regulation of glutamate-cysteine ligase gene expression by butylated hydroxytoluene is mediated by transcription factor AP-1.
Several regulatory elements, including AP-1 and NF-kappa B, are present in the 5'flanking region of the human glutamatex-cysteine ligase (EC 6.3.2.2, gamma-glutamyl-cysteine synthetase) catalytic subunit (GLCLC) gene. In this study, we investigated the role of redox-sensitive transcription factors in the regulation of GLCLC gene expression in LLC-PK1 cells that were exposed to the antioxidant butylated hydroxytoluene (BHT). Exposure of LLC-PK1 cells to 100 microM BHT induced expression of transcription factor AP-1, as demonstrated by an electrophoretic mobility shift assay. Peak AP-1 induction occurred after 3 h of incubation with BHT, BHT increased luciferase gene expression in cells that were transfected with a luciferase reporter vector containing an AP-1 element upstream of a SV40 promoter. Northern analysis showed that transcription of GLCLC gene in cells after incubation with BHT was increased 30% compared with control cells. Cellular glutathione concentrations were also significantly increased in cells exposed to BHT. In contrast, exposure of LLC-PK1 cells to 100 microM BHT did not alter expression of the transcription factor NF-kappa B. These results show that induction of transcription factor AP-1 by BHT is involved in transactivation of GLCLC gene expression.
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Department of Pharmacology and Physiology, School of Medicine and Dentistry, University of Rochester, New York 14642, USA.
Anders
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D000975:Antioxidants / Q000494:pharmacology*; D002084:Butylated Hydroxytoluene / Q000494:pharmacology*; D002478:Cells, Cultured; D017930:Genes, Reporter; D005721:Glutamate-Cysteine Ligase / Q000096:biosynthesis* / Q000235:genetics; D005978:Glutathione / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis; D018808:Transcription Factor AP-1 / Q000378:metabolism*; D015533:Transcriptional Activation; D015854:Up-Regulation
D000975:Antioxidants; D012333:RNA, Messenger; D018808:Transcription Factor AP-1; D002084:Butylated Hydroxytoluene; D005721:Glutamate-Cysteine Ligase; D005978:Glutathione