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.

[1]  J. D. Engel,et al.  Evaluation of MafG interaction with Maf recognition element arrays by surface plasmon resonance imaging technique , 2004, Genes to cells : devoted to molecular & cellular mechanisms.

[2]  J. D. Engel,et al.  Impaired megakaryopoiesis and behavioral defects in mafG-null mutant mice. , 1998, Genes & development.

[3]  Masayuki Yamamoto,et al.  A core region of the mafK gene IN promoter directs neurone‐specific transcription in vivo , 1998, Genes to cells : devoted to molecular & cellular mechanisms.

[4]  K. Itoh,et al.  An Nrf2/small Maf heterodimer mediates the induction of phase II detoxifying enzyme genes through antioxidant response elements. , 1997, Biochemical and biophysical research communications.

[5]  J. D. Engel,et al.  Small Maf Compound Mutants Display Central Nervous System Neuronal Degeneration, Aberrant Transcription, and Bach Protein Mislocalization Coincident with Myoclonus and Abnormal Startle Response , 2003, Molecular and Cellular Biology.

[6]  E Yoshida,et al.  Two domains of Nrf2 cooperatively bind CBP, a CREB binding protein, and synergistically activate transcription , 2001, Genes to cells : devoted to molecular & cellular mechanisms.

[7]  K. Davies,et al.  Oxidative stress induces the levels of a MafG homolog in hamster HA-1 cells. , 1996, Free radical biology & medicine.

[8]  J. D. Engel,et al.  Characterization of the Murine mafF Gene* , 1999, The Journal of Biological Chemistry.

[9]  H. Heng,et al.  Complexity of CNC Transcription Factors As Revealed by Gene Targeting of the Nrf3 Locus , 2004, Molecular and Cellular Biology.

[10]  Laura Leung,et al.  Deficiency of the Nrf1 and Nrf2 Transcription Factors Results in Early Embryonic Lethality and Severe Oxidative Stress* , 2003, Journal of Biological Chemistry.

[11]  K. Itoh,et al.  Activity and Expression of Murine Small Maf Family Protein MafK (*) , 1995, The Journal of Biological Chemistry.

[12]  T. Kensler,et al.  Antioxidant-inducible genes. , 1997, Advances in pharmacology.

[13]  J. D. Engel,et al.  The world according to Maf. , 1997, Nucleic acids research.

[14]  Ken Itoh,et al.  Transcription Factor Nrf2 Coordinately Regulates a Group of Oxidative Stress-inducible Genes in Macrophages* , 2000, The Journal of Biological Chemistry.

[15]  J. D. Engel,et al.  Perinatal synthetic lethality and hematopoietic defects in compound mafG::mafK mutant mice , 2000, The EMBO journal.

[16]  S. Dhakshinamoorthy,et al.  Small Maf (MafG and MafK) Proteins Negatively Regulate Antioxidant Response Element-mediated Expression and Antioxidant Induction of the NAD(P)H:Quinone Oxidoreductase1 Gene* , 2000, The Journal of Biological Chemistry.

[17]  James Douglas Engel,et al.  Integration and diversity of the regulatory network composed of Maf and CNC families of transcription factors. , 2002, Gene.

[18]  D. Ginzinger,et al.  Nrf1 Is Critical for Redox Balance and Survival of Liver Cells during Development , 2003, Molecular and Cellular Biology.

[19]  S. Orkin,et al.  Complexity of the erythroid transcription factor NF-E2 as revealed by gene targeting of the mouse p18 NF-E2 locus. , 1996, Proceedings of the National Academy of Sciences of the United States of America.

[20]  W. Wasserman,et al.  Functional antioxidant responsive elements. , 1997, Proceedings of the National Academy of Sciences of the United States of America.

[21]  Makoto Kobayashi,et al.  MafT, a new member of the small Maf protein family in zebrafish. , 2004, Biochemical and biophysical research communications.

[22]  K. Kataoka,et al.  Small Maf proteins heterodimerize with Fos and may act as competitive repressors of the NF-E2 transcription factor , 1995, Molecular and cellular biology.

[23]  J. D. Engel,et al.  Mesodermal‐ vs. neuronal‐specific expression of MafK is elicited by different promoters , 1996, Genes to cells : devoted to molecular & cellular mechanisms.

[24]  Hiroshi Suzuki,et al.  Hemoprotein Bach1 regulates enhancer availability of heme oxygenase‐1 gene , 2002, The EMBO journal.

[25]  Satoru Takahashi,et al.  The transcriptional programme of antibody class switching involves the repressor Bach2 , 2004, Nature.

[26]  W. Wasserman,et al.  Comprehensive analysis of proteins which interact with the antioxidant responsive element: correlation of ARE-BP-1 with the chemoprotective induction response. , 1997, Archives of biochemistry and biophysics.

[27]  A. Dinkova-Kostova,et al.  Importance of phase 2 gene regulation in protection against electrophile and reactive oxygen toxicity and carcinogenesis. , 2003, Advances in enzyme regulation.

[28]  C. B. Pickett,et al.  Transcriptional Regulation of the Antioxidant Response Element , 2000, The Journal of Biological Chemistry.

[29]  K. Itoh,et al.  Identification of a novel Nrf2-regulated antioxidant response element (ARE) in the mouse NAD(P)H:quinone oxidoreductase 1 gene: reassessment of the ARE consensus sequence. , 2003, The Biochemical journal.

[30]  J. D. Engel,et al.  Positive or Negative MARE-Dependent Transcriptional Regulation Is Determined by the Abundance of Small Maf Proteins , 2000, Cell.