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Genes to Cells, 2011

Cap'n'Collar (CNC) proteins heterodimerize with small Maf proteins and regulate the transcription of various genes. Small Maf-deficient mice develop severe neurodegeneration, and it remains unclear whether CNC proteins are involved in this process. In this study, we examined the contribution of Nrf1, one of the CNC proteins, to neuronal homeostasis in vivo. As Nrf1 gene knockout mice are embryonic lethal, we developed a central nervous system (CNS)specific Nrf1 knockout (CKO) mouse line using mice bearing an Nrf1 flox allele and Nestin-Cre allele. At birth, the CKO mice appeared indistinguishable from control mice, but thereafter they showed progressive motor ataxia and severe weight loss. All Nrf1 CKO mice died within 3 weeks. These phenotypes are similar to those reported in small Maf-deficient mice, suggesting the presence of collaboration between Nrf1 and small Maf proteins. We also found aberrant accumulation of polyubiquitinated proteins in various CNS regions and apparent neuronal loss in the hippocampus of Nrf1 CKO mice. An oxidative stress marker was accumulated in the spinal cords of the mice, but the expression patterns of oxidative stress response genes regulated by Nrf2 did not change substantially. These results show that Nrf1 sustains the CNS homeostasis through regulating target genes distinct from those regulated by Nrf2.

Nucleic Acids Research, 2010

The Nrf2 (nuclear factor E2 p45-related factor 2) transcription factor responds to diverse oxidative and electrophilic environmental stresses by circumventing repression by Keap1, translocating to the nucleus, and activating cytoprotective genes. Nrf2 responses provide protection against chemical carcinogenesis, chronic inflammation, neurodegeneration, emphysema, asthma and sepsis in murine models. Nrf2 regulates the expression of a plethora of genes that detoxify oxidants and electrophiles and repair or remove damaged macromolecules, such as through proteasomal processing. However, many direct targets of Nrf2 remain undefined. Here, mouse embryonic fibroblasts (MEF) with either constitutive nuclear accumulation (Keap1 À/À ) or depletion (Nrf2 À/À ) of Nrf2 were utilized to perform chromatin-immunoprecipitation with parallel sequencing (ChIP-Seq) and global transcription profiling. This unique Nrf2 ChIP-Seq dataset is highly enriched for Nrf2-binding motifs. Integrating ChIP-Seq and microarray analyses, we identified 645 basal and 654 inducible direct targets of Nrf2, with 244 genes at the intersection. Modulated pathways in stress response and cell proliferation distinguish the inducible and basal programs. Results were confirmed in an in vivo stress model of cigarette smoke-exposed mice. This study reveals global circuitry of the Nrf2 stress response emphasizing Nrf2 as a central node in cell survival response.

Cancer Letters, 2001

This article provides an overview of the mechanisms by which cancer chemopreventive blocking agents increase the expression of detoxication and antioxidant genes. These agents all appear capable of transcriptionally activating a gene battery that includes NAD(P)H:quinone oxidoreductase, aldo-keto reductases, glutathione S-transferases, g-glutamylcysteine synthetase, glutathione synthetase and heme oxygenase. Gene induction occurs through the antioxidant responsive element (ARE), a process that is dependent on the Nuclear Factor-Erythroid 2p45-related factors, Nrf1 and Nrf2. Under basal conditions, these basic region leucine zipper (bZIP) transcription factors are located in the cytoplasm of the cell bound to Keap1, and upon challenge with inducing agents, they are released from Keap1 and translocate to the nucleus. Within the nucleus, Nrf1 and Nrf2 are recruited to the ARE as heterodimers with either small Maf proteins, FosB, c-Jun, JunD, activating transcription factor 2 (ATF2) or ATF4. The role of protein kinases in transducing chemical stress signals to the bZIP factors that affect gene induction through the ARE is discussed.

PLoS ONE, 2011

Background: Without appropriate cellular models the etiology of idiopathic Parkinson's disease remains unknown. We recently reported a novel patient-derived cellular model generated from biopsies of the olfactory mucosa (termed olfactory neurosphere-derived (hONS) cells) which express functional and genetic differences in a disease-specific manner. Transcriptomic analysis of Patient and Control hONS cells identified the NRF2 transcription factor signalling pathway as the most differentially expressed in Parkinson's disease.

Biochemical …, 2005

Biochemical Society Transactions, 2015

Nuclear factor-erythroid 2 p45 (NF-E2 p45)-related factor 2 (Nrf2) is a master regulator of redox homoeostasis that allows cells to adapt to oxidative stress and also promotes cell proliferation. In this review, we describe the molecular mechanisms by which oxidants/electrophilic agents and growth factors increase Nrf2 activity. In the former case, oxidants/electrophiles increase the stability of Nrf2 by antagonizing the ability of Kelch-like ECH-associated protein 1 (Keap1) to target the transcription factor for proteasomal degradation via the cullin-3 (Cul3)–RING ubiquitin ligase CRLKeap1. In the latter case, we speculate that growth factors increase the stability of Nrf2 by stimulating phosphoinositide 3-kinase (PI3K)−protein kinase B (PKB)/Akt signalling, which in turn results in inhibitory phosphorylation of glycogen synthase kinase-3 (GSK-3) and in doing so prevents the formation of a DSGIS motif-containing phosphodegron in Nrf2 that is recognized by the β-transducin repeat-co...

Cell Biology and Toxicology

The aryl hydrocarbon receptor (AhR) is a ligand-binding protein that responds to environmental aromatic hydrocarbons and stimulates the transcription of downstream phase I enzyme–related genes by binding the cis element of dioxin-responsive elements (DREs)/xenobiotic-responsive elements. Dimethyl sulfoxide (DMSO) is a well-known organic solvent that is often used to dissolve phase I reagents in toxicology and oxidative stress research experiments. In the current study, we discovered that 0.1% DMSO significantly induced the activation of the AhR promoter via DREs and produced reactive oxygen species, which induced apoptosis in mouse embryonic fibroblasts (MEFs). Moreover, Jun dimerization protein 2 (Jdp2) was found to be required for activation of the AhR promoter in response to DMSO. Coimmunoprecipitation and chromatin immunoprecipitation studies demonstrated that the phase I–dependent transcription factors, AhR and the AhR nuclear translocator, and phase II–dependent transcription ...

Diabetes, 2014

Transcription factor Nrf2 (NF-E2-related factor 2) regulates wide-ranging cytoprotective genes in response to environmental stress. Keap1 (Kelch-like ECH-associated protein 1) is an adaptor protein for Cullin3-based ubiquitin E3 ligase and negatively regulates Nrf2. The Keap1-Nrf2 system plays important roles in the oxidative stress response and metabolism. However, the roles Nrf2 plays in prevention of pancreatic b-cell damage remain elusive. To demonstrate the roles of Nrf2 in pancreatic b-cells, we used four genetically engineered mouse models: 1) b-cell-specific Keap1conditional knockout mice, 2) b-cell-specific Nos2 transgenic mice, 3) conventional Nrf2-heterozygous knockout mice, and 4) b-cell-specific Nrf2conditional knockout mice. We found that Nrf2 induction suppressed the oxidative DNA-adduct formation in pancreatic islets of iNOS-Tg mice and strongly restored insulin secretion from pancreatic b-cells in the context of reactive species (RS) damage. Consistently, Nrf2 suppressed accumulation of intracellular RS in isolated islets and pancreatic b-cell lines and also decreased nitrotyrosine levels. Nrf2 induced glutathione-related genes and reduced pancreatic b-cell apoptosis mediated by nitric oxide. In contrast, Nrf2 depletion in Nrf2-heterozygous knockout and b-cell-specific Nrf2-conditional knockout mice strongly aggravated pancreatic b-cell damage. These results demonstrate that Nrf2 induction prevents RS damage in pancreatic b-cells and that the Keap1-Nrf2 system is the crucial defense pathway for the physiological and pathological protection of pancreatic b-cells.

Digestive Medicine Research

The proteins of MAF family (the cellular counterpart o f v i r a l o n c o g e n e M A F, i s o l a t e d f r o m a v i a n musculoaponeurotic fibrosarcoma) are transcription factors regulating gene expression. On the bases of the size, they are sub-grouped into two families: the "large" (L-MAFs: MAFA, MAFB, c-MAF, and Nrl) and the "small" (S-MAFs: MAFF, MAFK, and MAFG) MAF proteins (1). The MAFs are evolutionary conserved among vertebrates, and they are expressed in a wide range of tissues. All MAFs harbor a basic sequence binding DNA, in turn linked to a leucine zipper domain (b-ZIP), and forming homo/hetero-dimers with transcription factors containing the b-ZIP-region. L-MAFs recognize a T-MARE region, containing TPA responsive elements (TRE), and a C-MARE region, containing cAMP responsive elements (CRE). MARE motifs are flanked by three conserved residues "TGC" and "GCA", at their 5'-and 3'-ends, respectively. These flanking nucleotides guarantee the inherent ability to recognize specific DNA sequences (2). Regulation of MAF proteins expression and function The transcriptional activation domain (TAD) drives the effect of l-MAF subgroup. S-MAF, lacking TAD sequence, exert a positive or a negative regulatory activity, depending on specific partner and cellular context. S-MAF homodimers repress gene transcription, by binding to MAF recognition elements MARE (TGCTGACTCAGCA), within the target genes (1). In addition to the transcription regulators containing bZip regions, Jun, Fos, and Bach1, and several other factors heterodimerize with v-/c-MAF proteins. The component of the helix-loop-helix zipper transcription factors, USF2 inhibits c-MAF. In turn, c-MAF forms with c-Myb a transcriptionally inert complex, involved to guide the development of myeloid cells lineage. Similarly, MAFB represses the transcriptional activity of c-Ets-1, inhibiting erythroid cells differentiation (3). Many observations reveal the importance of s-MAFs in various biological pathways, and underline that a variety of signals modulates s-MAF functions, at transcriptional and/ or post-transcriptional levels. S-MAFs heterodimerize with NF-E2-related factor 2 (Nrf2), Nrf1, or Nrf3, as with Bach1 and Bach2 factors, functioning as transcriptional activators or repressors. S-MAFs positively modulate hypoxic response by binding the ARE (antioxidant responsive element) sequence of HIF-1α gene. The hypercapnia induces MAFG-mRNA in the central baroreceptive neurons. P h e n y l e p h r i n e i n d u c e s M A F G a c t i v a t i o n o f t h e baroreceptors. MAFG and its variant MAFG-2 expression decrease, when the extracellular environment shows an imbalance of its acid/base composition, which favors MAFG dimerization with FosB, and the DNA binding activity of the heterodimer (4). The wild-type protein, but not the sumoylation defective MAFG mutant, represses target gene expression in vivo, suggesting the critical role of sumoylation for MAFG activity. Novel studies revealed that only MAFG conjugated to SUMO2/3, exerts repression activity. In addition, sumoylation at Lysine 14 is Editorial

MAFG (v-Maf avian musculoaponeurotic fibrosarcoma oncogene homolog G) is a bZIP-type transcriptional regulator that belongs to the small MAF (sMAFs) protein family. By interacting with other bZIP transcription factors, sMAFs can form homo-and heterodimers governing either repressive or activating transcriptional functions. As heterodimeric partner of Nrf2, MAFG positively influences the ARE-dependent antioxidant/xenobiotic pathways, at least in condition of a correct MAFG:Nrf2 balance. MicroRNAs (miRs) participate to different regulatory networks being involved as fine-tuning regulators of gene expression. However, the connections between cellular surveillance to stresses mediated by MAFG:Nrf2 and miR regulations are not well understood. Here, we explored the impact of miR-128 in expression of genes related to stress response. Bioinformatic predictions coupled with functional analysis revealed the presence of miR-128 binding site in the 3 ′ UTR of MAFG. Ectopic miR-128 expression correlated with reduced expression of endogenous MAFG-dependent genes and negatively affected ARE-mediated molecular phenotype based on Nrf2 activity. Indeed, miR-128 impairs redox-dependent pathways induced in response to oxidative stress. Moreover, in condition of hypoxia, MAFG induction correlated with reduced levels of miR-128. This lead to increased mRNA levels of HMOX-1 and x-CT for blunting stress. Overall, these findings identify MAFG as novel direct target of miR-128.