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. 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. Cells have the ability to adapt to oxidative stress or to exposure to xenobiotics. By inducing a battery of antioxidant and xenobiotic metabolizing enzymes, such as glutathione S-transferase, heme oxygenase-1 (HO-1), 1The abbreviations used are: HO-1, heme oxygenase-1; ARE, antioxidant response element; ChIP, chromatin immunoprecipitation; DEM, diethyl maleate; EMSA, electrophoretic mobility shift assay; LDH, lactose dehydrogenase; MARE, maf recognition element; MEF, mouse embryonic fibroblast; NQO1, NAD(P)H:quinone oxidoreductase 1; PRDX1, peroxiredoxin 1; RACE, rapid amplification of cDNA ends; RT, reverse transcription. and NAD(P)H:quinone oxidoreductase 1 (NQO1), cells protect themselves from oxidative stress and xenobiotics (1Primiano T. Sutter T.R. Kensler T.W. Adv. Pharmacol. 1997; 38: 293-328Crossref PubMed Scopus (99) Google Scholar, 2Talalay P. Dinkova-Kostova A.T. Holtzclaw W.D. Adv. Enzyme Regul. 2003; 43: 121-134Crossref PubMed Scopus (258) Google Scholar). It has long been known that the genes encoding these enzymes are often coordinately regulated through AREs in their gene-regulatory regions (2Talalay P. Dinkova-Kostova A.T. Holtzclaw W.D. Adv. Enzyme Regul. 2003; 43: 121-134Crossref PubMed Scopus (258) Google Scholar). The ARE is a Maf (musculo-aponeurotic fibrosarcoma) recognition element (MARE)-related sequence, with strong similarity to the MARE (3Kataoka K. Igarashi K. Itoh K. Fujiwara K.T. Noda M. Yamamoto M. Nishizawa M. Mol. Cell. Biol. 1995; 15: 2180-2190Crossref PubMed Scopus (200) Google Scholar) (see Fig. 4A). Basic region-leucine zipper transcription factors, including CNC (Cap'n'Collar protein) family (Nrf1, Nrf2, Nrf3, and p45 NF-E2) and Bach (BTB and CNC homology) proteins (Bach1 and Bach2), form heterodimeric partners with a small Maf protein (MafG, MafK, and MafF), and then associate with various MARE-related sequences (including AREs).Fig. 4A putative ARE in the mafG gene Ic promoter. A, alignment of the MARE, the short ARE, the long ARE, the mafG Ic-ARE, and the ARE from the mouse NQO1 gene regulatory region. The MafG genomic locus is depicted at the top. The boxes represent exons, and the circle indicates the position of the mafG Ic-ARE. Each sequence was aligned, with asterisks indicating the nucleotides that are identical between the long ARE and the MafG Ic-ARE or between the MafG Ic-ARE and the NQO1 ARE. B, comparison of the first exons and the 5′ upstream regulatory regions of human and mouse mafG genes. For A and B, the arrows indicate nucleotides corresponding to the long ARE. The TPA response elopement core sequence of the MARE is shaded in dark gray. The GC boxes of the MARE are shaded in light gray. The abbreviations follow standard IUPAC nomenclature (where M represents A or C, R is A or G, Y is C or T, W is A or T, and S is G or C).View Large Image Figure ViewerDownload Hi-res image Download (PPT) CNC and Bach proteins possess transcriptional activation and repression domains, respectively. Therefore, ARE-mediated transcription is either positively or negatively regulated, depending on which basic region-leucine zipper factors bind to the ARE(s). Whereas small Maf proteins lack any recognizable transcriptional effector domains (other than the basic regionleucine zipper motif), they are nonetheless regarded as critical regulators of ARE-mediated transcription, since CNC and Bach proteins require them as obligatory partners for site-specific association with the ARE. Moreover, it is well documented that homodimers and heterodimers composed exclusively of small Maf proteins can act as repressive competitors to small Maf/CNC and small Maf/Bach heterodimers. One implication of these data is that small Maf proteins can participate in both positive and negative regulation of MARE-dependent genes. Additionally, the amount of small Maf proteins could be an important determinant of the transcriptional activity of target genes (for reviews, see Refs. 4Motohashi H. Shavit J.A. Igarashi K. Yamamoto M. Engel J.D. Nucleic Acids Res. 1997; 25: 2953-2959Crossref PubMed Scopus (238) Google Scholar and 5Motohashi H. O'Connor T. Katsuoka F. Engel J.D. Yamamoto M. Gene (Amst.). 2002; 294: 1-12Crossref PubMed Scopus (387) Google Scholar). The positive contributions of CNC proteins and the negative contributions of Bach1 to ARE-mediated transcription have been validated by gene targeting strategies. ARE-dependent gene induction was greatly impaired in nrf2-null mutant mice (6Itoh K. Chiba T. Takahashi S. Ishii T. Igarashi K. Katoh Y. Oyake T. Hayashi N. Satoh K. Hatayama I. Yamamoto M. Nabeshima Y. Biochem. Biophys. Res. Commun. 1997; 236: 313-322Crossref PubMed Scopus (3226) Google Scholar), and Nrf1 is also reported to contribute to the activation of ARE-dependent genes (7Chen L. Kwong M. Lu R. Ginzinger D. Lee C. Leung L. Chan J.Y. Mol. Cell. Biol. 2003; 23: 4673-4686Crossref PubMed Scopus (111) Google Scholar, 8Leung L. Kwong M. Hou S. Lee C. Chan J.Y. J. Biol. Chem. 2003; 278: 48021-48029Abstract Full Text Full Text PDF PubMed Scopus (247) Google Scholar). The ARE-dependent HO-1 gene was significantly derepressed in bach1-null mutant mice, suggesting that HO-1 is negatively regulated by Bach1 (9Sun J. Hoshino H. Takaku K. Nakajima O. Muto A. Suzuki H. Tashiro S. Takahashi S. Shibahara S. Alam J. Taketo M.M. Yamamoto M. Igarashi K. EMBO J. 2002; 21: 5216-5224Crossref PubMed Scopus (525) Google Scholar). Although nrf3-null and bach2-null mutant mice have been reported (10Derjuga A. Gourley T.S. Holm T.M. Heng H.H. Shivdasani R.A. Ahmed R. Andrews N.C. Blank V. Mol. Cell. Biol. 2004; 24: 3286-3294Crossref PubMed Scopus (76) Google Scholar, 11Muto A. Tashiro S. Nakajima O. Hoshino H. Takahashi S. Sakoda E. Ikebe D. Yamamoto M. Igarashi K. Nature. 2004; 429: 566-571Crossref PubMed Scopus (221) Google Scholar), the contribution of these factors to ARE-mediated regulation is still to be determined. In comparison with the cnc and bach family-targeted mutant mice, the phenotypes of small maf mutant mice were expected to be more complicated, since small Maf proteins can participate in both positive and negative regulation. The functions of small Maf proteins are compensatory and provide partially overlapping redundancy, since small maf single mutant mice (mafG–/–, mafK–/–, and mafF–/–) showed mild or subtle phenotypes (12Kotkow K.J. Orkin S.H. Proc. Natl. Acad. Sci. U. S. A. 1996; 93: 3514-3518Crossref PubMed Scopus (45) Google Scholar, 13Shavit J.A. Motohashi H. Onodera K. Akasaka J. Yamamoto M. Engel J.D. Genes Dev. 1998; 12: 2164-2174Crossref PubMed Scopus (97) Google Scholar, 14Onodera K. Shavit J.A. Motohashi H. Katsuoka F. Akasaka J.E. Engel J.D. Yamamoto M. J. Biol. Chem. 1999; 274: 21162-21169Abstract Full Text Full Text PDF PubMed Scopus (50) Google Scholar), whereas small maf compound mutant mice (mafG–/–:mafF–/– and mafG–/–:mafF–/–:mafK–/–) displayed a greater number of and more profound deficiencies (15Onodera K. Shavit J.A. Motohashi H. Yamamoto M. Engel J.D. EMBO J. 2000; 19: 1335-1345Crossref PubMed Scopus (82) Google Scholar, 16Katsuoka F. Motohashi H. Tamagawa Y. Kure S. Igarashi K. Engel J.D. Yamamoto M. Mol. Cell. Biol. 2003; 23: 1163-1174Crossref PubMed Scopus (44) Google Scholar). We recently observed that a fraction of ARE-dependent genes (e.g. NQO1 and thioredoxin reductase 1) are not normally induced in either small maf compound mutant mice or in nrf2-null mutant mice. 2F. Katsuoka, H. Motohashi, J. D. Engel, and M. Yamamoto, unpublished observations. Therefore, we concluded that small Maf proteins act cooperatively with Nrf2 to activate the transcription of these genes. In contrast, HO-1 transcription is derepressed in small maf compound mutant mice, similarly to the bach1-null mutant (16Katsuoka F. Motohashi H. Tamagawa Y. Kure S. Igarashi K. Engel J.D. Yamamoto M. Mol. Cell. Biol. 2003; 23: 1163-1174Crossref PubMed Scopus (44) Google Scholar), suggesting that small Maf proteins are also important for collaboratively repressing HO-1. In this way, we genetically confirmed that small Maf proteins act as required cofactors in both positive and negative MARE-dependent regulation of gene transcription. In the course of previous gene we found that diethyl maleate (DEM), a well known of genes, induced the of mafG. Katsuoka, H. Motohashi, J. D. Engel, and M. Yamamoto, for that mafG is an gene. the that mafG transcription are we that a promoter ARE mafG By electrophoretic mobility shift and chromatin immunoprecipitation we demonstrate that Nrf2 and small Maf proteins bind to the mafG ARE. We also that induction of mafG is impaired in nrf2-null mutant cells. mafG is an gene. of mouse was (6Itoh K. Chiba T. Takahashi S. Ishii T. Igarashi K. Katoh Y. Oyake T. Hayashi N. Satoh K. Hatayama I. Yamamoto M. Nabeshima Y. Biochem. Biophys. Res. Commun. 1997; 236: 313-322Crossref PubMed Scopus (3226) Google Scholar). The mice used in this were on a of and were from at embryonic The and were and the was and in were in and To ARE-dependent genes, were with DEM for was from mouse or from mouse embryonic the cDNA was from the and was as K. Shavit J.A. Motohashi H. Katsuoka F. Akasaka J.E. Engel J.D. Yamamoto M. J. Biol. Chem. 1999; 274: 21162-21169Abstract Full Text Full Text PDF PubMed Scopus (50) Google Scholar). of the and used for mafG have been K. Shavit J.A. Motohashi H. Katsuoka F. Akasaka J.E. Engel J.D. Yamamoto M. J. Biol. Chem. 1999; 274: 21162-21169Abstract Full Text Full Text PDF PubMed Scopus (50) Google Scholar), and used for each mafG are in I. The and were at a to and (see of to in a was on and to a were from the by for the sequences of the used in this are as HO-1 T. Itoh K. Takahashi S. H. T. Katoh Y. S. Yamamoto M. J. Biol. Chem. 2000; Full Text Full Text PDF PubMed Scopus Google Scholar), NQO1 (6Itoh K. Chiba T. Takahashi S. Ishii T. Igarashi K. Katoh Y. Oyake T. Hayashi N. Satoh K. Hatayama I. Yamamoto M. Nabeshima Y. Biochem. Biophys. Res. Commun. 1997; 236: 313-322Crossref PubMed Scopus (3226) Google Scholar), and peroxiredoxin 1 T. Itoh K. Takahashi S. H. T. Katoh Y. S. Yamamoto M. J. Biol. Chem. 2000; Full Text Full Text PDF PubMed Scopus Google Scholar). of cDNA was with from a mouse embryonic the cDNA amplification to the The sequences of the are as and were and their sequences were determined. Y. Itoh K. E. M. A. Yamamoto M. Genes PubMed Scopus Google Scholar) and MafG M. Yamamoto T. Motohashi H. T. T. T. Engel J.D. Yamamoto M. Genes 2004; PubMed Scopus Google Scholar) were with at the and by The and were with and with the and respectively. To a of and and their corresponding mutant with in Fig. and were amount of from to or a of competitors was of the and proteins with or competitors was as (3Kataoka K. Igarashi K. Itoh K. Fujiwara K.T. Noda M. Yamamoto M. Nishizawa M. Mol. Cell. Biol. 1995; 15: 2180-2190Crossref PubMed Scopus (200) Google Scholar). The and were by on a in cells were in and and in a Nrf2 cDNA was (3Kataoka K. Igarashi K. Itoh K. Fujiwara K.T. Noda M. Yamamoto M. Nishizawa M. Mol. Cell. Biol. 1995; 15: 2180-2190Crossref PubMed Scopus (200) Google Scholar) and used for of Nrf2 H. Katsuoka F. Shavit J.A. Engel J.D. Yamamoto M. Cell. 2000; Full Text Full Text PDF PubMed Google Scholar) was used for of mouse To the of and were and K. Itoh K. Motohashi H. Hayashi N. Y. H. Nishizawa M. Yamamoto M. J. Biol. Chem. 1995; Full Text Full Text PDF PubMed Scopus Google Scholar). To and their mutant a of and either or any were and These and the were the cells cells were and the were used for The of both and were a activity was to activity for was as P. M. Itoh K. Yamamoto M. J.D. Biochem. J. 2003; PubMed Scopus Google Scholar). were or or a of was used for with the NQO1 ARE P. M. Itoh K. Yamamoto M. J.D. Biochem. J. 2003; PubMed Scopus Google gene promoter P. M. Itoh K. Yamamoto M. J.D. Biochem. J. 2003; PubMed Scopus Google and mafG Ic and MafG Gene by an we found that DEM, a well known of genes, induced the of mafG in To this we with DEM and examined the of small maf genes by Among the small maf genes, mafG was the significantly induced by DEM of mafG DEM mafG is a gene induced at a in the course of the The HO-1 gene showed a induction the induction of ARE-dependent genes, such as NQO1 and PRDX1, DEM The mafG Gene the mafG we examined transcriptional regulation of the mafG gene. We the mouse mafG locus and coding exons and not the of the first J.A. Motohashi H. Onodera K. Akasaka J. Yamamoto M. Engel J.D. Genes Dev. 1998; 12: 2164-2174Crossref PubMed Scopus (97) Google Scholar). Therefore, we first to first by the mafG gene and three and We also one which has an Ic first exon and sequence between the Ic and second exon the between exons and that this sequence was not to genomic We these and are also found in the mouse and or not they are To the we a which to the of each we each and used them as a number standard for These results that each is In the the and Ic were Whereas the was used more this to be in such as and The of the was than the Ic In of the MafG in a that is on suggesting that transcriptional regulatory from each of the three mafG ARE in the of mafG the mafG are in response to We cDNA from cells or with The and Ic were significantly induced by DEM, whereas the was not DEM the was still the of the mafG upon comparison of the induction for each we found that Ic was induced through the mafG genomic locus in we a ARE sequence 5′ to exon Ic (Ic-ARE) 4A). The Ic-ARE partially the ARE sequence and is to the ARE in the NQO1 regulatory element 4A). data to the of a putative first exon for human mafG corresponding to the mouse Ic exon The of exon Ic is conserved between mice and including the putative mafG promoter Ic-ARE Nrf2/MafG and the mafG of the Nrf2/small Maf heterodimer to the Ic-ARE was examined by To the of the mafG Ic-ARE, we it with the ARE in the mouse NQO1 gene as a positive The that the Nrf2/MafG heterodimer well to the mafG promoter ARE The of the heterodimer for the Ic-ARE to be than for the in contrast, MafG homodimers to the the The to the were by a of not by the mutant nucleotides at both of the TPA response element the These results showed that of Nrf2 and MafG on the of the TPA response element core sequence of the To the these were by the of a of the a in the sequence of the short ARE The both of the a single ARE in a with mutant a of competitors showed that was with the in the ability to the These results showed that the nucleotides in are not critical for the of Nrf2/MafG heterodimer and MafG to Ic-ARE at in To the mafG promoter Ic-ARE is we ARE sequences were genes and cells. In to a comparison with the activity of a known ARE, we either the ARE from mafG promoter or the ARE from the mouse NQO1 gene. The ARE gene was activated by with the Nrf2 The was activated to with that Nrf2 and MafG The induction of the gene was either the mafG promoter or NQO1 promoter ARE We further the Ic-ARE activity by the of mutant AREs in induction of the gene that is normally by the Nrf2 was observed with a gene an with the of EMSA, this showed that the TPA response element core sequence of the Ic-ARE is Whereas not the activity of this induction of the ARE gene It is that both and genes were activated both Nrf2 and MafG were by of factors was to activate the gene the These suggest that the sequences of the short ARE are important for induction of mafG transcription. Nrf2 and Maf with the mafG to the of the data from both and were cells. To of Nrf2, cells were with DEM for with and used for The association of Nrf2 with the NQO1 ARE was first examined as a positive P. M. Itoh K. Yamamoto M. J.D. Biochem. J. 2003; PubMed Scopus Google Scholar). Nrf2 and small associate with the NQO1 ARE in cells in cells In the of or in the presence of failed to the NQO1 ARE well as genomic that the were not in The gene promoter was not with either Nrf2 or small suggesting that the used in a such these showed that both Nrf2 and small with the mafG Ic-ARE in cells These results that Nrf2 and small can associate with an genomic the mafG promoter Ic-ARE. small also with the mafG Ic-ARE in suggesting of the Ic-ARE by either or repressive to DEM of the mafG Gene on we to the of mafG transcription on Nrf2 To this we nrf2-null embryonic the cells with DEM, and examined mafG DEM the of mafG was in nrf2-null mutant cells comparison with by mafG was significantly activated in nrf2-null mutant cells DEM, whereas a induction of the mafG was observed in cells These results demonstrate that mafG induction is on In this we examined the transcriptional regulation of the mouse mafG gene and concluded that mafG is itself an ARE-dependent gene by In with the Nrf2 have also been reported to the mafG gene. A mafG was as a gene in a of gene Y. K.J. Biol. 1996; 21: PubMed Scopus Google Scholar). reported that a induces human J.A. Biochem. J. 2002; PubMed Google Scholar). it has been reported that the mafG is by DEM Y. M. L. Suzuki T. K. Yamamoto M. Biochem. Biophys. Res. Commun. 2004; PubMed Scopus (50) Google Scholar). mafG to be a gene in we the first exons of mafG by we found that the mouse mafG gene has at three first exons and We reported that and also have first exons K. Shavit J.A. Motohashi H. Katsuoka F. Akasaka J.E. Engel J.D. Yamamoto M. J. Biol. Chem. 1999; 274: 21162-21169Abstract Full Text Full Text PDF PubMed Scopus (50) Google Scholar, H. Igarashi K. Onodera K. Takahashi S. H. M. Nishizawa M. Engel J.D. Yamamoto M. Genes 1996; PubMed Scopus Google Scholar). it that three small maf genes first exons. MafG not to have first exons, such as the exon that is exclusively in H. J. Engel J.D. Yamamoto M. Genes 1998; PubMed Scopus Google Scholar). revealed that mafG first exons are in various on the sequences from the we concluded that of the of mafG a in the of the We that first exons itself as a by which small maf genes can not Although we a of mafG that the between exon Ic and exon and is at a is to be determined. three first exons of mafG were induced upon oxidative Whereas the was the and DEM the Ic was the activated by DEM to These that the first in their response to The critical transcription that could be for induction was to be an ARE(s). We for AREs in the mafG locus and one in the proximal promoter of exon Although the short ARE sequence was as revealed that such as the one in the NQO1 are often by a long ARE sequence, P. M. Itoh K. Yamamoto M. J.D. Biochem. J. 2003; PubMed Scopus Google Scholar, Proc. Natl. Acad. Sci. U. S. A. 1997; PubMed Scopus Google Scholar). the mafG Ic-ARE is to the sequence and is also to the ARE found in the NQO1 gene regulatory region. the Ic-ARE is well conserved in the human we that these AREs are conserved for mafG regulation. In at previous failed to activation of AREs by Nrf2 and small Maf proteins S. J. Biol. Chem. 2000; Full Text Full Text PDF PubMed Scopus Google Scholar, T. J. Biol. Chem. 2000; Full Text Full Text PDF PubMed Scopus Google Scholar). Although we also failed to this transcriptional activation in or we in cells. In the we observed that the transcription by the mafG Ic-ARE was cooperatively activated by Nrf2 and In this a the short ARE of the Ic-ARE greatly induction of the gene by Nrf2 and this not the of the heterodimer in EMSA, which the sequence of ARE, might play critical roles with the heterodimer in the transcriptional activation Biochem. Biophys. 1997; PubMed Scopus Google Scholar). for the ARE sequence as important for strong showed that Nrf2 to the mafG Ic-ARE in a Moreover, DEM of nrf2-null mutant cells to mafG is not to that these data a contribution of Nrf1 or to mafG in Nrf1 is to for the of In Nrf2 and Nrf1 have been to play important roles in ARE-dependent gene induction in an overlapping L. Kwong M. Hou S. Lee C. Chan J.Y. J. Biol. Chem. 2003; 278: 48021-48029Abstract Full Text Full Text PDF PubMed Scopus (247) Google Scholar). also showed that small bind to the mafG Ic-ARE. Although the small Maf used in the MafK, we that three small Maf proteins can bind to the mafG Ic-ARE, since this is conserved the small Maf proteins H. O'Connor T. Katsuoka F. Engel J.D. Yamamoto M. Gene (Amst.). 2002; 294: 1-12Crossref PubMed Scopus (387) Google Scholar). showed that small bind to the mafG Ic-ARE in cells indicating that is the small Maf activity independent of MafG is to bind to the mafG Ic-ARE in EMSA, it is that small Maf proteins form homodimers by themselves and the mafG Ic-ARE in cells. it is also that small Maf proteins with Bach1 to form a transcriptional The heterodimer mafG gene transcription through mafG Ic-ARE in the as it HO-1 gene (9Sun J. Hoshino H. Takaku K. Nakajima O. Muto A. Suzuki H. Tashiro S. Takahashi S. Shibahara S. Alam J. Taketo M.M. Yamamoto M. Igarashi K. EMBO J. 2002; 21: 5216-5224Crossref PubMed Scopus (525) Google Scholar, 16Katsuoka F. Motohashi H. Tamagawa Y. Kure S. Igarashi K. Engel J.D. Yamamoto M. Mol. Cell. Biol. 2003; 23: 1163-1174Crossref PubMed Scopus (44) Google Scholar). The contribution of Bach1 proteins to the regulation of mafG is also showed that ARE-dependent genes are not induced by mafG and HO-1 were whereas NQO1 and were These to the of the induction of mafG upon exposure to oxidative It is that induced genes the of ARE-dependent genes. MafG could be as a heterodimeric for Nrf2 to further ARE-dependent genes at a of the induced MafG might with Bach1 or with itself to ARE-dependent genes. These are not We recently found that ARE-dependent genes are regulated by small Maf MafG induction on the of target genes, depending on their We Y. for the Nrf2 and T. T. Yamamoto, and R. for