Project description:Nrf2 (NF-E2-related factor-2) transcription factor regulates oxidative/xenobiotic stress response and also represses inflammation. However, the mechanisms how Nrf2 alleviates inflammation are still unclear. Here, we demonstrate that Nrf2 interferes with lipopolysaccharide-induced transcriptional upregulation of proinflammatory cytokines, including IL-6 and IL-1β. ChIP-seq and ChIP-qPCR analyses revealed that Nrf2 binds to the proximity of these genes in macrophages and inhibits RNA Pol II recruitment. Further, we found that Nrf2-mediated inhibition is independent of the Nrf2 binding motif and reactive oxygen species level. Murine inflammatory models further demonstrated that Nrf2 interferes with IL6 induction and inflammatory phenotypes in vivo. Thus, contrary to the widely accepted view that Nrf2 suppresses inflammation through redox control, we demonstrate here that Nrf2 opposes transcriptional upregulation of proinflammatory cytokine genes. This study identifies Nrf2 as the upstream regulator of cytokine production and establishes a molecular basis for an Nrf2-mediated anti-inflammation approach. Gene expression in BMDMs obtained from wild-type and Keap1-CKO mice. In Keap1-CKO (Keap1 flox/flox::LysM-Cre) BMDMs, Nrf2 transcription factor is activated due to Keap1-deficiency. BMDMs were obtained by a culture of bone marrow cells in the presence of M-CSF for7 days. M1-activated BMDMs were obtained by stimulation with LPS and IFNg for 6 hours, while M2-activated BMDMs were obtained by a stimulation with IL-4 for 6 hours. Two independent BMDM cultures were performed, and each experiment contains samples obtained from one wild-type and one Keap1-CKO mice, respectively.
Project description:Nrf2 (NF-E2-related factor-2) transcription factor regulates oxidative/xenobiotic stress response and also represses inflammation. However, the mechanisms how Nrf2 alleviates inflammation are still unclear. Here, we demonstrate that Nrf2 interferes with lipopolysaccharide-induced transcriptional upregulation of proinflammatory cytokines, including IL-6 and IL-1β. ChIP-seq and ChIP-qPCR analyses revealed that Nrf2 binds to the proximity of these genes in macrophages and inhibits RNA Pol II recruitment. Further, we found that Nrf2-mediated inhibition is independent of the Nrf2 binding motif and reactive oxygen species level. Murine inflammatory models further demonstrated that Nrf2 interferes with IL6 induction and inflammatory phenotypes in vivo. Thus, contrary to the widely accepted view that Nrf2 suppresses inflammation through redox control, we demonstrate here that Nrf2 opposes transcriptional upregulation of proinflammatory cytokine genes. This study identifies Nrf2 as the upstream regulator of cytokine production and establishes a molecular basis for an Nrf2-mediated anti-inflammation approach.
Project description:Due to the limited expression of several antioxidant enzymes, β-cells are highly vulnerable to high ROS levels, which can lead to the reduction of functional β-cell mass. During early postnatal ages, both human and rodent β-cells go through a burst of proliferation that quickly declines with age. Here we discovered that the expression of the master antioxidant regulator, Nrf2, is increased during this postnatal burst of β-cell proliferation in humans. Additionally, data from β-cell specific Nrf2 deletion in mice demonstrated that Nrf2 is required for β-cell proliferation, β-cell survival, β-cell identity and β-cell mass expansion at early stages of life. Daily administration of antioxidant NAC to newborn mice showed that Nrf2 mechanism of action strongly relies on maintaining normal redox balance. Interestingly, RNAseq of islets isolated from β-cell specific Nrf2 deleted mice suggests that Nrf2 regulates neonatal β-cell proliferation by promoting mitochondrial ATP synthesis. Our study highlights Nrf2 as an essential transcription factor for maintaining redox balance as well as mitochondrial biogenesis and function to support neonatal β-cell growth and for maintaining functional β-cell mass in adulthood under metabolic stress.
Project description:Transcription factor nuclear factor erythroid 2 p45-related factor 2 (Nrf2) and its main negative regulator, Kelch-like ECH associated protein 1 (Keap1), are at the interface between redox and intermediary metabolism, allowing adaptation and survival under conditions of oxidative, inflammatory and metabolic stress. Nrf2 is the principal determinant of redox homeostasis, and contributes to mitochondrial function and integrity, and cellular bioenergetics. Using proteomics and lipidomics, we show that genetic downregulation of Keap1 in mice, and the consequent Nrf2 activation to pharmacologically-relevant levels, leads to upregulation of carboxylesterase 1 (Ces1) and acyl-CoA oxidase 2 (Acox2), decreases triglycerides levels, and alters the lipidome. This is accompanied by downregulation of hepatic ATP-citrate lyase (Acly) and decreased levels of acetyl-CoA, a trigger for autophagy. These findings suggest that downregulation of Keap1 confers features of a fasted metabolic state, which is an important consideration in the drug development of Keap1-targeting pharmacologic Nrf2 activators.
Project description:Hereditary Leiomyomatosis and renal cell cancer is caused by fumarate hydratase loss of heterozygosity and subsequence accumulation of fumarate. Fumarate is known to activate the anti-oxidant response and is key for cellular survival. Fumarate succinates KEAP1 which releases NRF2 to activate the antioxidant response. The role of fumarate on the global regulatory chromatin landscape is less understood. Here, by integrating chromatin accessibility and histone ChIP-seq profiles, we identify complex transcription factor networks involved in the highly remodelled chromatin landscape of FH-deficient cells. We implicate FOXA2 in the maintenance of FH-deficient cells by regulating anti-oxidant response genes and subsequent metabolic output, independent of NRF2. These results identify new redox and amino acid metabolism regulators and provide new avenues for therapeutic intervention.
Project description: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−/−) or depletion (Nrf2−/−) 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.
Project description:The NRF2 transcription factor controls a cell stress program that is implicated in cancer and there is great interest in targeting NRF2 for therapy. We show that NRF2 activity depends on Fructosamine-3-kinase (FN3K) - a kinase that triggers protein de-glycation. In its absence, NRF2 is extensively glycated, unstable, and defective at binding to small MAF proteins and transcriptional activation. Moreover, the development of hepatocellular carcinoma triggered by MYC and Keap1 inactivation depends on FN3K in vivo. N-acetyl cysteine treatment partially rescues the effects of FN3K loss on NRF2 driven tumor phenotypes indicating a key role for NRF2-mediated redox balance. Mass spectrometry reveals that other proteins undergo FN3K-sensitive glycation, including translation factors, heat shock proteins, and histones. How glycation affects their functions remains to be defined. In summary, our study reveals a surprising role for the glycation of cellular proteins and implicates FN3K as targetable modulator of NRF2 activity in cancer.
Project description:To overcome oxidative, inflammatory, and metabolic stress, cells have evolved networks of cytoprotective proteins controlled by transcription factor nuclear factor erythroid 2 p45-related factor 2 (Nrf2) and its main negative regulator the Kelch-like ECH associated protein 1 (Keap1). Here, we used high-resolution mass-spectrometry to characterize the proteomes of macrophages with altered Nrf2 status. Our analysis revealed significant differences among the genotypes in cellular metabolism and redox homeostasis, which we validated with Seahorse flux and metabolomics, as well as in anti-viral immune pathways, translational regulation and mitosis. Nrf2 disruption significantly affected the proteome following lipopolysaccharide (LPS) stimulation, with alterations in redox, carbohydrate and lipid metabolism, and innate immunity predominantly. Of note, LPS stimulation was found to promote mitochondrial fusion in a process that was dependent on Nrf2. The Keap1 inhibitor, 4-octyl itaconate (4-OI), a derivative of the mitochondrial immunometabolite itaconate, remodeled the inflammatory macrophage proteome, increasing redox and suppressing anti-viral immune effectors in a Nrf2-dependent manner. These data suggest that Nrf2 activation facilitates metabolic reprogramming, mitochondrial adaptation, and finetunes the innate immune response in macrophages.
Project description:Resveratrol is a natural product that has gained tremendous interest due to multiple reported health-beneficial effects. However, the underlying mechanisms of action of this compound remained largely controversial. Here, we demonstrate that major biological effects of resveratrol might be attributed to its bicarbonate-induced production of phenolic radicals and reactive oxygen species (ROS) such as superoxide and hydrogen peroxide under physiologically relevant conditions. These products derived from low hormetic micromolar concentrations of resveratrol led to gene expression reprogramming, which was mainly controlled by the redox-sensitive transcription factor nuclear factor (erythroid-derived 2) like 2 (Nrf2), whereas too high concentrations of resveratrol became detrimental for cells. Gentle but significant activation of Nrf2-controlled gene expression resulted in a metabolic switch and reduced cellular redox environment. Thereby cells could be preconditioned against stress, for example to protect primary keratinocytes of the human epidermis from oxidative stress that was induced by metabolization of ethanol. Hormetic shifting of cells by chemical triggers such as resveratrol towards a more reductive state might represent a powerful conceptual framework to improve cellular fitness at low nontoxic concentrations. Total RNA obtained from cultured primary neonatal normal human epidermal keratinocytes (NHEK) subjected to 16 hours treatment with 50 µM resveratrol (trans-3,5,4â-trihydroxystilbene, RSV) compared to vehicle-treated control NHEKs.
Project description:RATIONALE: Mechanical ventilation (MV) is an indispensable therapy for critically ill patients with acute lung injury and the adult respiratory distress syndrome. However, the mechanisms by which conventional MV induces lung injury remain unclear. OBJECTIVES: We hypothesized that disruption of the gene encoding Nrf2, a transcription factor which regulates the induction of several antioxidant enzymes, enhances susceptibility to ventilator-induced lung injury (VILI), while antioxidant supplementation attenuates such effect. METHODS: To test our hypothesis and to examine the relevance of oxidative stress in VILI, here we have assessed lung injury and inflammatory responses in Nrf2-deficient (Nrf2(-/-)) mice and wildtype (Nrf2(+/+)) animals following acute (2 h) injurious model of MV with or without administration of antioxidant. MEASUREMENTS AND MAIN RESULTS: Nrf2(-/-) mice displayed greater levels of lung alveolar and vascular permeability and inflammatory responses to MV as compared to Nrf2(+/+) mice. Nrf2-deficieny enhances the levels of several pro-inflammatory cytokines implicated in the pathogenesis of VILI. We found diminished levels of critical antioxidant enzymes and redox imbalance by MV in the lungs of Nrf2(-/-) mice; however antioxidant supplementation to Nrf2(-/-) mice remarkably attenuated VILI. When subjected to clinically relevant prolong period of MV, Nrf2(-/-) mice displayed greater levels of VILI than Nrf2(+/+) mice. Expression profiling revealed lack of induction of several VILI genes, stress response and solute carrier proteins and phosphatases in Nrf2(-/-) mice. CONCLUSIONS: Collectively, our data demonstrate for the first time a critical role for Nrf2 in VILI, which confers protection against cellular responses induced by MV by modulating oxidative stress. Experiment Overall Design: The Nrf2 wildtype (Nrf2+/+) and Nrf2-deficient (Nrf2â/â) CD-1/ICR strains of mice were subjected to mechanical ventilation with high (HVT) amounts of tidal volumes (VT) at 30 ml/kg for 2 hours. The animals subjected to spontaneous ventilation (SpV) for 2 hours were used as controls. Lungs were immediately removed and processed for total RNA isolation using TRIzol reagent (LifeTechnologies, Grand Island, NY). The isolated RNA was applied to Murine Genome 430A GeneChip arrays (Affymetrix, Santa Clara, CA), which contain probes for detecting ~14,500 well-characterized genes and 4371 expressed sequence tags according to standard microarray protocol. Scanned output files were analyzed by using Affymetrix GeneChip Operating Software and were independently normalized to an average intensity of 500.