Nrf2 transcriptionally activates the mafG gene through an antioxidant response element.
Nrf2 accumulates in nuclei upon exposure to oxidative stress, heterodimerizes with a small Maf protein, and activates the transcription of stress target genes through antioxidant response elements (AREs). We found that diethyl maleate (DEM), a well known activator of Nrf2, induces one of the small Maf genes, mafG. To elucidate roles MafG might play in the oxidative stress response, we examined transcriptional regulation of the mouse mafG gene. MafG utilizes three independent first exons that are each spliced to second and third coding exons. Among the small maf genes, mafG showed the strongest response to DEM, and of the three first exons, the highest -fold induction was seen with the proximal first exon (Ic). Importantly, one ARE (Ic-ARE) is conserved in the promoter flanking exon Ic of the human and mouse mafG genes. The Nrf2/MafG heterodimer bound the Ic-ARE and activated transcription, whereas DEM failed to activate mafG in nrf2-null mutant cells. Chromatin immunoprecipitation further revealed that both Nrf2 and small Maf proteins associate with the Ic-ARE in vivo. These results demonstrate that mafG is itself an ARE-dependent gene that is regulated by an Nrf2/small Maf heterodimer and suggest the presence of an autoregulatory feedback pathway for mafG transcriptional regulation.
Katsuoka
Fumiki
F
Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba 305-8577, Japan.
Motohashi
Hozumi
H
Engel
James Douglas
JD
Yamamoto
Masayuki
M
D000818:Animals; D000975:Antioxidants / Q000378:metabolism*; D001483:Base Sequence; D002460:Cell Line; D047369:Chromatin Immunoprecipitation; D002875:Chromosomes / Q000648:ultrastructure; D003062:Codon; D018076:DNA, Complementary / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism / Q000502:physiology*; D019281:Dimerization; D004305:Dose-Response Relationship, Drug; D005091:Exons; D005347:Fibroblasts / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D051259:MafG Transcription Factor; D008298:Maleates / Q000737:chemistry; D051379:Mice; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009154:Mutation; D051267:NF-E2-Related Factor 2; D009841:Oligonucleotides / Q000737:chemistry; D018384:Oxidative Stress; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D020033:Protein Isoforms; D012313:RNA / Q000378:metabolism; D012097:Repressor Proteins / Q000502:physiology*; D020218:Response Elements; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012689:Sequence Homology, Nucleic Acid; D013997:Time Factors; D015534:Trans-Activators / Q000378:metabolism / Q000502:physiology*; D014158:Transcription, Genetic; D014162:Transfection
D000975:Antioxidants; D003062:Codon; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D051259:MafG Transcription Factor; C491247:Mafg protein, mouse; D008298:Maleates; D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; C495636:Nfe2l2 protein, mouse; D009841:Oligonucleotides; D020033:Protein Isoforms; D012097:Repressor Proteins; D015534:Trans-Activators; D012313:RNA; C014476:diethyl maleate