Nrf2 Activation Research Articles

Sugar-mediated non-canonical ubiquitination impairs Nrf1/NFE2L1 activation

Proteasome is essential for cell survival, and proteasome inhibition induces proteasomal gene transcription via the activated endoplasmic-reticulum-associated transcription factor nuclear factor erythroid 2-like 1(Nrf1/NFE2L1). Nrf1 activation requires proteolytic cleavage by DDI2 and N-glycan removal by NGLY1. We previously showed that Nrf1 ubiquitination by SKP1-CUL1-F-box (SCF)FBS2/FBXO6, an N-glycan-recognizing E3 ubiquitin ligase, impairs its activation, although the molecular mechanism remained elusive. Here, we show that SCFFBS2 cooperates with the RING-between-RING (RBR)-type E3 ligase ARIH1 to ubiquitinate Nrf1 through oxyester bonds in human cells. Endo-β-N-acetylglucosaminidase (ENGASE) generates asparagine-linked N-acetyl glucosamine (N-GlcNAc) residues from N-glycans, and N-GlcNAc residues on Nrf1 served as acceptor sites for SCFFBS2-ARIH1-mediated ubiquitination. We reconstituted the polyubiquitination of N-GlcNAc and serine/threonine residues on glycopeptides and found that the RBR-specific E2 enzyme UBE2L3 is required for the assembly of atypical ubiquitin chains on Nrf1. The atypical ubiquitin chains inhibited DDI2-mediated activation. The present results identify an unconventional ubiquitination pathway that inhibits Nrf1 activation.

Ezetimibe ketone protects against renal ischemia-reperfusion injury and attenuates oxidative stress via activation of the Nrf2/HO-1 signaling pathway.

Recently, ezetimibe (EZM) has been suggested to be a potent Nrf2 activator that is important for preventing oxidative stress. Interestingly, we found that its metabolite ezetimibe ketone (EZM-K) also has antioxidant effects. Thus, we investigated the role of EZM-K in preventing renal ischemia‒reperfusion injury (RIRI). Cultured NRK-52E cells were subjected to simulated IR with or without EZM-K. Rats were used to simulate in vivo experiments. EZM-K alleviated H2O2-induced apoptosis and reactive oxygen species (ROS) and upregulated Nrf2 and HO-1 levels in NRK-52E cells. A HO-1 and a Nrf2 inhibitor reversed the protective effects of EZM-K. In the rat RIRI model, pretreatment with EZM-K activated the Nrf2/HO-1 signaling pathway, suppressed tubular injury and inflammation, and improved renal function. EZM-K significantly prevented renal injury caused by ischemia‒reperfusion via the Nrf2/HO-1 signaling axis both in vivo and in vitro. The other metabolite of EZM, ezetimibe glucuronide (EZM-G) had no protective effects against ROS in RIRI. EZM-G also had no antioxidant effects and could not activate Nrf2/HO-1 signal pathway. Our findings also indicated the therapeutic potential of EZM-K in preventing RIRI.

Exploring the cytoprotective potential of flavonoid fraction from Carica papaya L. Cultivar ‘Red Lady' Leaf: Insights into Nrf2 activation via in-vitro and in-silico approaches

Flavonoids play a significant role in mitigating the production of reactive oxygen species (ROS) and subsequent oxidative stress. In the present study we aimed to evaluate the cytoprotective and antioxidant defense mechanism of flavonoid fraction from Carica papaya L. (FFCP) leaf in human PBMC. For this investigation, the human PBMCs were lotted into three groups viz., negative control, positive control (treated with H2O2), and experiment group (pretreated with FFCP and challenged with H2O2). The cytoprotective mechanism was evaluated by assessing the intracellular ROS and Ca2+ mobilization, membrane and DNA damages, antioxidant enzymes, and Nrf2 activation. In-silico analysis was employed for assessing the interactions of flavonoids in FFCP with the Nrf2 binding pocket of Keap 1 protein. The results of the experiment unveiled that FFCP protected the human PBMCs from H2O2 induced oxidative damages such as lipid peroxidation, LDH leakage, DNA breakage, reduced the intracellular ROS and Ca2+ mobilization as compared to positive control. FFCP pretreatment effectively improved the activity of key antioxidant enzyme markers, such as SOD (1.66 ± 0.032-fold increase), CAT (2.24 ± 0.09-fold increase), GPx (1.94 ± 0.05-fold increase), and GR (1.81 ± 0.14-fold increase). Furthermore, the FFCP modulated the Nrf2 gene expression (a 2.38 ± 0.25 -fold) and its translocation into the nucleus as compared to the positive control. In-silico analysis enunciated that all flavonoids exhibited strong affinity with the Nrf2 binding pocket of Keap1 protein via stable hydrogen bonding and hydrophobic interactions. These observations suggest that FFCP is a natural source of bioactive compounds with nutraceutical benefits for combating oxidative stress-associated diseases by protecting the cells from oxidative stress induced damages as well as by instigating antioxidant defense mechanisms.

Catalpol from Rehmannia glutinosa Targets Nrf2/NF-κB Signaling Pathway to Improve Renal Anemia and Fibrosis.

Rehmannia glutinosa is widely recognized as a prominent medicinal herb employed by practitioners across various generations for the purpose of fortifying kidney yin. Within Rehmannia glutinosa, the compound known as catalpol (CAT) holds significant importance as a bioactive constituent. However, the protective effects of CAT on kidneys, including ameliorative effects on chronic kidney disease - most prominently renal anemia and renal fibrosis - have not been clearly defined. In this study, the kidney injury model of NRK-52E cells and C57BL/6N male mice was prepared by exposure to aristolochic acid I (AA-I), and it was discovered that CAT could ameliorate oxidative stress injury, inflammatory injury, apoptosis, renal anemia, renal fibrosis, and other renal injuries both in vivo and in vitro. Further treatment of NRK-52E cells with Nrf2 inhibitors (ML385) and activators (ML334), as well as NF-κB inhibitors (PDTC), validated CAT's ability to target Nrf2 activation. Furthermore, the expression of phosphorylated NF-κB p65, IL-6, and Cleaved-Caspase3 protein was inhibited. CAT also inhibited NF-κB, and then inhibited the expression of IL-6, p-STAS3, TGF-β1 protein. Therefore, CAT can regulate Nrf2/NF-κB signaling pathway, significantly correct renal anemia and renal fibrosis, and is conducive to the preservation of renal structure and function, thus achieving a protective effect on the kidneys.

Neurological Manifestations Following Traumatic Brain Injury: Role of Behavioral, Neuroinflammation, Excitotoxicity, Nrf-2 and Nitric Oxide.

Traumatic Brain Injury (TBI) is attributed to a forceful impact on the brain caused by sharp, penetrating bodies, like bullets and any sharp object. Some popular instances like falls, traffic accidents, physical assaults, and athletic injuries frequently cause TBI. TBI is the primary cause of both mortality and disability among young children and adults. Several individuals experience psychiatric problems, including cognitive dysfunction, depression, post-traumatic stress disorder, and anxiety, after primary injury. Behavioral changes post TBI include cognitive deficits and emotional instability (anxiety, depression, and post-traumatic stress disorder). These alterations are linked to neuroinflammatory processes. On the other hand, the direct impact mitigates inflammation insult by the release of pro-inflammatory cytokines, namely IL-1β, IL-6, and TNF-α, exacerbating neuronal injury and contributing to neurodegeneration. During the excitotoxic phase, activation of glutamate subunits like NMDA enhances the influx of Ca2+ and leads to mitochondrial metabolic impairment and calpain-mediated cytoskeletal disassembly. TBI pathological insult is also linked to transcriptional response suppression Nrf-2, which plays a critical role against TBI-induced oxidative stress. Activation of NRF-2 enhances the expression of anti-oxidant enzymes, providing neuroprotection. A possible explanation for the elevated levels of NO is that the stimulation of NMDA receptors by glutamate leads to the influx of calcium in the postsynaptic region, activating NOS's constitutive isoforms.

Pharmacologic Inhibition of EIF4A Blocks NRF2 Synthesis to Prevent Osteosarcoma Metastasis.

Effective therapies for metastatic osteosarcoma (OS) remain a critical unmet need. Targeting mRNA translation in metastatic OS offers a promising option, as selective translation drives the synthesis of cytoprotective proteins under harsh microenvironmental conditions to facilitate metastatic competence. We assessed the expression levels of eukaryotic translation factors in OS, revealing the high expression of the eukaryotic initiation factor 4A1 (EIF4A1). Using a panel of metastatic OS cell lines and patient-derived xenograft (PDX) models, EIF4A1 inhibitors were evaluated for their ability to block proliferation and reduce survival under oxidative stress, mimicking harsh conditions of the lung microenvironment. Inhibitors were also evaluated for their antimetastatic activity using the ex vivo pulmonary metastasis assay and in vivo metastasis models. Proteomics was performed to catalog which cytoprotective proteins or pathways were affected by EIF4A1 inhibition. CR-1-31B, a rocaglate-based EIF4A1 inhibitor, exhibited nanomolar cytotoxicity against all metastatic OS models tested. CR-1-31B exacerbated oxidative stress and apoptosis when OS cells were co-treated with tert-butylhydroquinone, a chemical oxidative stress inducer. CR-1-31B potently inhibited OS growth in the pulmonary metastasis assay model and in experimental and spontaneous models of OS lung metastasis. Proteomic analysis revealed that tert-butylhydroquinone-mediated upregulation of the NRF2 antioxidant factor was blocked by co-treatment with CR-1-31B. Genetic inactivation of NRF2 phenocopied the antimetastatic activity of CR-1-31B. Finally, the clinical-grade EIF4A1 phase-1-to-2 inhibitor, zotatifin, similarly blocked NRF2 synthesis and the OS metastatic phenotype. Collectively, our data reveal that pharmacologic targeting of EIF4A1 is highly effective in blocking OS metastasis by blunting the NRF2 antioxidant response.

Rosolic acid as a novel activator of the Nrf2/ARE pathway in arsenic-induced male reproductive toxicity: An in silico study

Male reproductive toxicity as a result of arsenic exposure is linked with oxidative stress and excessive generation of reactive oxygen species (ROS). It leads to an imbalance between ROS production and antioxidant defense mechanisms ultimately resulting in male infertility. The nuclear factor erythroid 2 (NFE2)-related factor 2 (Nrf2) is a transcription factor that responds to cellular stressors controlling the oxidative state, mitochondrial dysfunction, inflammation, and proteostasis. This study aims to investigate the potential of Rosolic acid (ROA) to act as a novel Nrf2 activator by mitigating oxidative stress to combat arsenic-induced male reproductive toxicity. The protein and ligands were prepared in the BIOVIA Discovery Studio, followed by protein-ligand docking using auto dock vina integrated with the PyRx-Virtual Screening Tool. Then the ADME properties were analyzed using the SwissADME tool to get a clear idea about the physicochemical properties, lipophilicity, water solubility, pharmacokinetics, and drug likeliness of ROA. It was followed by molecular dynamics simulation (MDS) studies using GROMACS. The 3D and 2D interaction maps revealed the interactions of Keap 1 with ROA. Keap1-ROA complex was found to have a binding energy of −7.8 kcal/mol. ROA showed 0 violations for Lipinski and 0 alerts each for PAINS and Brenk and a bioavailability score of 0.55. The BOILED-Egg representation showcases that ROA is predicted as passively crossing the blood-brain barrier (BBB). The MDS described 2FLU-ROA as a stable system. This work portrays that ROA can be a potent Nrf2 activator by exhibiting an inhibitory activity against the Keap1 protein and thus mitigating oxidative stress in arsenic-induced male reproductive toxicity.

Cancer stem cells release interleukin-33 within large oncosomes to promote immunosuppressive differentiation of macrophage precursors

In squamous cell carcinoma (SCC), macrophages responding to interleukin (IL)-33 create a TGF-β-rich stromal niche that maintains cancer stem cells (CSCs), which evade chemotherapy-induced apoptosis in part via activation of the NRF2 antioxidant program. Here, we examined how IL-33 derived from CSCs facilitates the development of an immunosuppressive microenvironment. CSCs with high NRF2 activity redistributed nuclear IL-33 to the cytoplasm and released IL-33 as cargo of large oncosomes (LOs). Mechanistically, NRF2 increased the expression of the lipid scramblase ATG9B, which exposed an "eat me" signal on the LO surface, leading to annexin A1 (ANXA1) loading. These LOs promoted the differentiation of AXNA1 receptor+ myeloid precursors into immunosuppressive macrophages. Blocking ATG9B's scramblase activity or depleting ANXA1 decreased niche macrophages and hindered tumor progression. Thus, IL-33 is released from live CSCs via LOs to promote the differentiation of alternatively activated macrophage, with potential relevance to other settings of inflammation and tissue repair.

Exposure to volatile ferroptosis inhibitor, TEMPO, reduced cutaneous ischemia-reperfusion injury progression to pressure ulcer formation in a mouse model

BackgroundIschemia– reperfusion (I/R) injury-induced oxidative stress is a key factor in the pathogenesis of pressure ulcer formation. Ferroptosis is an iron-dependent programmed cell death that connects oxidative stress and inflammation in various diseases. Recent studies revealed the protective effect of inhibition of ferroptosis in I/R injury. However, the role of ferroptosis in cutaneous I/R injury remains elusive. ObjectiveTo assess the role of ferroptosis in the progression of cutaneous I/R injury. MethodsCutaneous I/R injury experiments and histopathological studies were performed in wild-type mice with or without exposure to volatile ferroptosis inhibitor, TEMPO (2,2,6,6-Tetramethylpiperidine-1-oxyl). The suppressive effects of TEMPO on ferroptosis inducing cell death and oxidative stress were examined in vitro. ResultsInhibition of ferroptosis with TEMPO significantly reduced ulcer formation after cutaneous I/R injury. Fluctuated ferroptosis markers, such as GPX4, ACSL4, and 4-HNE expression in the I/R skin site, were reversed by TEMPO treatment. Inhibition of ferroptosis reduced apoptosis, CD3+ infiltrating lymphocytes, and improved vascularity in the I/R skin site. Inhibition of ferroptosis also suppressed the enhancement of Nrf2 activation. In vitro, ferroptosis and the activation of ferroptosis-related gene expression by RSL3 stimulation were markedly ameliorated by TEMPO treatment in mouse fibroblasts. Inhibiting ferroptosis also suppressed the elevation of the mRNA levels of NOX2 and HO-1 caused by ferroptosis. ConclusionCutaneous I/R injury-induced ferroptosis likely promotes cell death, vascular loss, infiltration of inflammatory cells, and oxidative stress. The inhibition of ferroptosis with TEMPO might have potential clinical application as novel therapeutic agent for cutaneous I/R injury.

Geniposide alleviates heart failure with preserved ejection fraction in mice by regulating cardiac oxidative stress via MMP2/SIRT1/GSK3β pathway.

Heart failure with preserved ejection fraction (HFpEF) is a complex clinical syndrome with cardiac dysfunction, fluid retention and reduced exercise tolerance as the main manifestations. Current treatment of HFpEF is using combined medications of related comorbidities, there is an urgent need for a modest drug to treat HFpEF. Geniposide (GE), an iridoid glycoside extracted from Gardenia Jasminoides, has shown significant efficacy in the treatment of cardiovascular, digestive and central nervous system disorders. In this study we investigated the therapeutic effects of GE on HFpEF experimental models in vivo and in vitro. HFpEF was induced in mice by feeding with HFD and L-NAME (0.5 g/L) in drinking water for 8 weeks, meanwhile the mice were treated with GE (25, 50 mg/kg) every other day. Cardiac echocardiography and exhaustive exercise were performed, blood pressure was measured at the end of treatment, and heart tissue specimens were collected after the mice were euthanized. We showed that GE administration significantly ameliorated cardiac oxidative stress, inflammation, apoptosis, fibrosis and metabolic disturbances in the hearts of HFpEF mice. We demonstrated that GE promoted the transcriptional activation of Nrf2 by targeting MMP2 to affect upstream SIRT1 and downstream GSK3β, which in turn alleviated the oxidative stress in the hearts of HFpEF mice. In H9c2 cells and HL-1 cells, we showed that treatment with GE (1 μM) significantly alleviated H2O2-induced oxidative stress through the MMP2/SIRT1/GSK3β pathway. In summary, GE regulates cardiac oxidative stress via MMP2/SIRT1/GSK3β pathway and reduces cardiac inflammation, apoptosis, fibrosis and metabolic disorders as well as cardiac dysfunction in HFpEF. GE exerts anti-oxidative stress properties by binding to MMP2, inhibiting ROS generation in HFpEF through the SIRT1/Nrf2 signaling pathway. In addition, GE can also affect the inhibition of the downstream MMP2 target GSK3β, thereby suppressing the inflammatory and apoptotic responses in HFpEF. Taken together, GE alleviates oxidative stress/apoptosis/fibrosis and metabolic disorders as well as HFpEF through the MMP2/SIRT1/GSK3β signaling pathway.

Unlocking milk thistle’s anti-psoriatic potential in mice: Targeting PI3K/AKT/mTOR and KEAP1/NRF2/NF-κB pathways to modulate inflammation and oxidative stress

Silybum marianum, known as milk thistle (MT), is traditionally used to manage liver diseases. This study aimed to investigate the role of MT extract topical application as a potential treatment for imiquimod (IMQ)-induced psoriatic lesions in mice with particular emphasis on phosphoinositol-3 Kinase (PI3K)/ protein kinase B (AKT)/ mammalian target of rapamycin (mTOR) and Kelch-like ECH-associated protein 1 (KEAP1)/ nuclear factor erythroid-2-related factor (NRF2)/ nuclear factor-kappa B (NF-κB) molecular cascades involvement. To address this aim, forty male Swiss albino mice were subdivided into four groups (n = 10 mice/group): control, IMQ model, standard group where mice were treated topically with IMQ, then the anti-psoriatic mometasone cream, and MT extract-treated group where mice were treated topically with IMQ followed by MT extract. In most measured parameters, MT extract, rich in silymarin, exhibited potent anti-psoriatic activity comparable to the standard cortisone treatment. MT extract mitigated dorsal skin erythema, scaling, and epidermal thickening, reflected by lowering the Psoriasis Area Severity Index (PASI) score. Moreover, it alleviated IMQ-induced splenomegaly. Mechanistically, the PI3K/AKT/mTOR pathway was the main functional pathway behind such improvements, where it was significantly inhibited by MT extract application. This led to NRF2 activation via KEAP1 downregulation with subsequent anti-inflammatory effect proven by reducing NF-κB, interleukin (IL)–23, and IL-17A and antioxidant ability proven by boosting the antioxidant glutathione and heme oxygenase-1. Such improvements were confirmed by alleviating the histopathological alteration. Thus, MT extract could be a promising therapeutic agent for psoriasis treatment by inhibiting PI3K/AKT/mTOR cascade, along with NRF2 signaling activation.

Activation of Nuclear Factor Erythroid 2-Related Factor 2 Transcriptionally Upregulates Ectonucleotide Pyrophosphatase/Phosphodiesterase 1 Expression and Inhibits Ectopic Calcification in Mice.

Calcification plays a key role in biological processes, and breakdown of the regulatory mechanism results in a pathological state such as ectopic calcification. We hypothesized that ENPP1, the enzyme that produces the calcification inhibitor pyrophosphate, is transcriptionally regulated by Nrf2, and that Nrf2 activation augments ENPP1 expression to inhibit ectopic calcification. Cell culture experiments were performed using mouse osteoblastic cell line MC3T3-E1. Nrf2 was activated by 5-aminolevulinic acid and sodium ferrous citrate. Nrf2 overexpression was induced by the transient transfection of an Nrf2 expression plasmid. ENPP1 expression was monitored by real-time RT-PCR. Because the promoter region of ENPP1 contains several Nrf2-binding sites, chromatin immunoprecipitation using an anti-Nrf2 antibody followed by real-time PCR (ChIP-qPCR) was performed. The relationship between Nrf2 activation and osteoblastic differentiation was examined by alkaline phosphatase (ALP) and Alizarin red staining. We used mice with a hypomorphic mutation in ENPP1 (ttw mice) to analyze whether Nrf2 activation inhibits ectopic calcification. Nrf2 and Nrf2 overexpression augmented ENPP1 expression and inhibited osteoblastic differentiation, as indicated by ALP expression and calcium deposits. ChIP-qPCR showed that some putative Nrf2-binding sites in the ENPP1 promoter region were bound by Nrf2. Nrf2 activation inhibited ectopic calcification in mice. ENPP1 gene expression was transcriptionally regulated by Nrf2, and Nrf2 activation augmented ENPP1 expression, leading to the attenuation of osteoblastic differentiation and ectopic calcification in vitro and in vivo. Nrf2 activation has a therapeutic potential for preventing ectopic calcification.

African mesquite elicits neuroprotective activity against quaternary metal mixture -induced olfactory bulb-hippocampal oxido-inflammatory stress via nrf2-hmox-1pathway

African mesquite AM is widely used as an anti-inflammatory agent in sub-Sahara Africa especially Nigeria. Given its strong anti-inflammatory potency, this study has evaluated the neuroprotective properties of AM in the hippocampus HIP and olfactory bulb OB of rats exposed to Cd, As, Hg, and Pb. Twenty-five albino Sprague Dawley rats were randomly divided into five groups in this experiment. Group 1, the control received only water. Group 2 received heavy metal mixture HMM (PbCl2 (20 mg/kg), CdCl2 (1.61 mg/kg), HgCl2 (0.40 mg/kg), and NaAsO3 (10 mg/kg), for 60 days. Groups 3, 4, and 5 were treated with HMM along with AM at doses of 500, 1000, and 1500 mg/kg, respectively. AM decreased the Cd, As, Hg, and Pb levels in OB and HIP, restored the activities of antioxidants, Hmox-1, reduced the activities of AChE, NRF2 and NFkB and improved histopathology.

Saikosaponin A attenuates osteoclastogenesis and bone loss by inducing ferroptosis.

To alleviate bone loss, most current drugs target osteoclasts. Saikosaponin A (Ssa), a triterpene saponin derived from Bupleurum falcatum (also known as Radix bupleuri), has immunoregulatory, neuromodulatory, antiviral, anticancer, anti-convulsant, anti-inflammatory, and anti-proliferative effects. Recently, modulation of bone homeostasis was shown to involve ferroptosis. Herein, we aimed to determine Ssa's inhibitory effects on osteoclastogenesis and differentiation, whether ferroptosis is involved, and the underlying mechanisms. Tartrate-resistant acid phosphatase (TRAP) staining, F-actin staining, and pit formation assays were conducted to confirm Ssa-mediated inhibition of RANKL-induced osteoclastogenesis in vitro. Ssa could promote osteoclast ferroptosis and increase mitochondrial damage by promoting lipid peroxidation, as measured by iron quantification, FerroOrange staining, Dichloro-dihydro-fluorescein diacetate, MitoSOX, malondialdehyde, glutathione, and boron-dipyrromethene 581/591 C11 assays. Pathway analysis showed that Ssa can promote osteoclasts ferroptosis by inhibiting the Nrf2/SCL7A11/GPX4 axis. Notably, we found that the ferroptosis inhibitor ferrostatin-1 and the Nrf2 activator tert-Butylhydroquinone reversed the inhibitory effects of Ssa on RANKL-induced osteoclastogenesis. In vivo, micro-computed tomography, hematoxylin and eosin staining, TRAP staining, enzyme-linked immunosorbent assays, and immunofluorescence confirmed that in rats with periodontitis induced by lipopolysaccharide, treatment with Ssa reduced alveolar bone resorption dose-dependently. The results suggested Ssa as a promising drug to treat osteolytic diseases.

Protective Effects of Hepatocyte Stress Defenders, Nrf1 and Nrf2, against MASLD Progression.

Progression of metabolic dysfunction-associated steatites liver disease (MASLD) to steatohepatitis (MASH) is driven by stress-inducing lipids that promote liver inflammation and fibrosis, and MASH can lead to cirrhosis and hepatocellular carcinoma. Previously, we showed coordinated defenses regulated by transcription factors, nuclear factor erythroid 2-related factor-1 (Nrf1) and -2 (Nrf2), protect against hepatic lipid stress. Here, we investigated protective effects of hepatocyte Nrf1 and Nrf2 against MASH-linked liver fibrosis and tumorigenesis. Male and female mice with flox alleles for genes encoding Nrf1 (Nfe2l1), Nrf2 (Nfe2l2), or both were fed a MASH-inducing diet enriched with high fat, fructose, and cholesterol (HFFC) or a control diet for 24-52 weeks. During this period, hepatocyte Nrf1, Nrf2, or combined deficiency for ~7 days, ~7 weeks, and ~35 weeks was induced by administering mice hepatocyte-targeting adeno-associated virus (AAV) expressing Cre recombinase. The effects on MASH, markers of liver fibrosis and proliferation, and liver tumorigenesis were compared to control mice receiving AAV-expressing green fluorescent protein. Also, to assess the impact of Nrf1 and Nrf2 induction on liver fibrosis, HFFC diet-fed C57bl/6J mice received weekly injections of carbon tetrachloride, and from week 16 to 24, mice were treated with the Nrf2-activating drug bardoxolone, hepatocyte overexpression of human NRF1 (hNRF1), or both, and these groups were compared to control. Compared to the control diet, 24-week feeding with the HFFC diet increased bodyweight as well as liver weight, steatosis, and inflammation. It also increased hepatocyte proliferation and a marker of liver damage, p62. Hepatocyte Nrf1 and combined deficiency increased liver steatosis in control diet-fed but not HFFC diet-fed mice, and increased liver inflammation under both diet conditions. Hepatocyte Nrf1 deficiency also increased hepatocyte proliferation, whereas combined deficiency did not, and this also occurred for p62 level in control diet-fed conditions. In 52-week HFFC diet-fed mice, 35 weeks of hepatocyte Nrf1 deficiency, but not combined deficiency, resulted in more liver tumors in male mice, but not in female mice. In contrast, hepatocyte Nrf2 deficiency had no effect on any of these parameters. However, in the 15-week CCL4-exposed and 24-week HFFC diet-fed mice, Nrf2 induction with bardoxolone reduced liver steatosis, inflammation, fibrosis, and proliferation. Induction of hepatic Nrf1 activity with hNRF1 enhanced the effect of bardoxolone on steatosis and may have stimulated liver progenitor cells. Physiologic Nrf1 delays MASLD progression, Nrf2 induction alleviates MASH, and combined enhancement synergistically protects against steatosis and may facilitate liver repair.

Phosphocreatine attenuates doxorubicin-induced nephrotoxicity through inhibition of apoptosis, and restore mitochondrial function via activation of Nrf2 and PGC-1α pathways

Doxorubicin (DOX), a chemotherapy drug widely recognized for its efficacy in cancer treatment, unfortunately, has significant nephrotoxic effects leading to kidney damage. This study explores the nephroprotective potential of Phosphocreatine (PCr) in rats, specifically examining its influence on Nrf2 (Nuclear factor erythroid 2-related factor 2) and PGC-1α (Peroxisome proliferator-activated receptor gamma coactivator 1-alpha) pathways, its role in apoptosis inhibition, and effectiveness in preserving mitochondrial function. The research employed in vivo experiments in rats, focusing on PCr's capacity to protect renal function against doxorubicin-induced damage. The study entailed evaluating Nrf2 and PGC-1α pathway activation, apoptosis rates, and mitochondrial health in renal tissues. A significant aspect of this research was the use of high-resolution respirometry (HRR) to assess the function of isolated kidney mitochondria, providing in-depth insights into mitochondrial bioenergetics and respiratory efficiency under the influence of PCr and doxorubicin. Results demonstrated that PCr treatment significantly enhanced the activation of Nrf2 and PGC-1α pathways, reduced apoptosis, and preserved mitochondrial structure in doxorubicin-affected kidneys. Observations included upregulated expression of Nrf2 and PGC-1α target genes, stabilization of mitochondrial membranes, and a notable improvement in cellular antioxidant defense, evidenced by the activities of enzymes like superoxide dismutase (SOD), glutathione (GSH), malondialdehyde (MDA) This study positions phosphocreatine as a promising agent in mitigating doxorubicin-induced kidney damage in rats. The findings, particularly the insights from HRR on isolated kidney mitochondria, highlight PCr's potential in enhancing mitochondrial function and reducing nephrotoxic side effects of chemotherapy. These encouraging results pave the way for further research into PCr's applications in cancer treatment, aiming to improve patient outcomes by managing chemotherapy-related renal injuries.

Britanin alleviates chondrocyte ferroptosis in osteoarthritis by regulating the Nrf2-GPX4 axis

BackgroundOsteoarthritis (OA) is a chronic joint disease characterized by degeneration of the articular cartilage or inflamed joints. Britanin is a guaiacyl-type sesquiterpene lactone possessing anti-inflammatory and antioxidant activities. MethodsIn this study, western blotting, Reverse-transcription PCR (RT-PCR), and immunofluorescent staining method were used to clarifying the molecular mechanisms of britanin in alleviating chondrocyte ferroptosis. The effect of britanin on reactive oxygen species (ROS) and lipid peroxidation levels in chondrocytes was examined by Dihydroethidium (DHE) stain and fluorescent dye BODIPY581 / 591 C11. The destabilized medial meniscus (DMM) model was used to mimic OA, then britanin was injected into the knee articular cavity. The morphological analysis was performed by hematoxylin and eosin (H&E) staining, Safranin O-Fast green staining and Micro-computed tomography (Micro-CT) analysis. Immunohistochemical analysis and Immunofluorescence assay was conducted to verify the effect of britanin in vivo. ResultsThe results revealed that britanin treatment regulates the expression of chondrocyte extracellular matrix–related factors, such as ADAMTS5, MMP13, SOX9, aggrecan, and COL2A1. Britanin also significantly reversed the influence of interleukin (IL)-1β on the levels of reactive oxygen species and lipid peroxidation and upregulated glutathione peroxidase 4 (GPX4) expression in IL-1β-induced chondrocytes. Erastin could alleviate the effects of britanin on chondrocytes. Moreover, britanin could prevent IL-1β-induced oxidative stress and ferroptosis in chondrocytes. Britanin also upregulated the expression of nuclear factor E2–related factor 2 (Nrf2) in IL-1β-induced chondrocytes, and Nrf2 activator played a similar role as that of britanin in IL-1β-induced chondrocytes. Furthermore, injecting britanin into the knee joints of OA rats alleviated cartilage destruction caused by surgical resection. ConclusionsThese findings confirmed that britanin can inhibit ferroptosis in OA chondrocytes through the Nrf2-GPX4 pathway. Thus, britanin has the potential to be developed as a drug for OA therapy.

The Effect of Phytocannabinoids and Endocannabinoids on Nrf2 Activity in the Central Nervous System and Periphery.

The relationship between nuclear factor erythroid 2-related factor 2 (Nrf2) and phytocannabinoids/endocannabinoids (pCBs/eCBs) has been investigated in a variety of models of peripheral illnesses, with little clarification on their interaction within the central nervous system (CNS). In this context, evidence suggests that the Nrf2-pCBs/eCBS interaction is relevant in modulating peroxidation processes and the antioxidant system. Nrf2, one of the regulators of cellular redox homeostasis, appears to have a protective role toward damaging insults to neurons and glia by enhancing those genes involved in the regulation of homeostatic processes. Specifically in microglia and macroglia cells, Nrf2 can be activated, and its signaling pathway modulated, by both pCBs and eCBs. However, the precise effects of pCBs and eCBs on the Nrf2 signaling pathway are not completely elucidated yet, making their potential clinical employment still not fully understood.

UBE2C regulates the KEAP1/NRF2 signaling pathway to promote the growth of gastric cancer by inhibiting autophagy

Gastric cancer (GC) is one of the most common malignant tumors in the world, ranking fourth in incidence and second in mortality among malignant tumors. In recent years, there has been some progress in biological treatment and targeted treatment for gastric cancer, but the prognosis for gastric cancer patients remains pessimistic, and the molecular mechanisms involved are not yet clear. In this study, bioinformatics analysis showed that Ubiquitin-conjugating enzyme E2C(UBE2C) was abnormally expressed in various types of cancer. Furthermore, UBE2C protein and mRNA expression was significantly elevated in gastric cancer tissues and cells. Silencing UBE2C significantly inhibited the proliferation and migration of gastric cancer cells. Mechanistically, UBE2C overexpression inhibited gastric cancer cell autophagy, leading to the accumulation of p62. Furthermore, immunoprecipitation results showed that UBE2C overexpression promoted the interaction between p62 and KEAP1, while inhibiting the binding of NRF2 to KEAP1, thereby weakening the ubiquitination and degradation of NRF2. In addition, the silencing of UBE2C leads to a reduction in the nuclear accumulation of NRF2. Importantly, the NRF2 activator TBHQ reversed the inhibition of gastric cancer cell proliferation and migration caused by the silencing of UBE2C. In summary, our study provides new insights into the molecular mechanisms of UBE2C in anti-cancer therapy.

The therapeutic effect of NRF2 activator, ezetimibe, in cardiac cachexia.

Heart failure (HF) is caused by functional and structural irregularity leading to impaired ejection or filling capacity of the heart. HF leads to chronic inflammatory conditions in the heart leads to weight loss, anorexia, and muscle atrophy known as cachexia. The present study was carried out to investigate the role of Ezetimibe, an NRF2 activator, in cardiac cachexia and to develop a treatment strategy for cardiac cachexia. Balb/c mice of either sex at 6-8 weeks of age were given 2 mg/kg of doxorubicin in 0.9% sodium chloride solution intraperitoneally (i.p.) for the alternate days for the first week and then once a week for the next 4 weeks. After induction of cardiac atrophy, treatment with Ezetimibe (1.5 mg/kg, p.o) was given for the next 4 weeks. In the cardiac cachectic animals, a significant decrease in body weight, food, and water intake was observed. Cardiac cachectic animals showed a significant increase in serum glucose, total cholesterol, LDL, triglyceride, VLDL, CK-MB, LDH, and CRP levels. Cardiac atrophic index, heart weight to body weight ratios (HW/BW), right ventricular weight to heart weight ratios (RV/HW), and left ventricular weight to heart weight ratios (LV/HW), were significantly decreased in cardiac cachectic animals. The weights of the skeletal muscles such as EDL, gastrocnemius, soleus, tibialis anterior, and quadriceps muscles, and the weight of adipose tissue such as subcutaneous, visceral, perirenal, and brown adipose tissue were significantly decreased in the cardiac cachectic group relative to the normal group. Treatment with ezetimibe improves body weight, food intake, and water intake. Ezetimibe decreases serum glucose, total cholesterol, LDL, triglyceride, VLDL, CK-MB, LDH and CRP levels. Cardiac atrophic markers such as HW/BW, RV/HW, and LV/HW were improved. The weight of skeletal muscles and adipose tissue was increased after treatment with ezetimibe. Our data showed that the NRF2 activator, Ezetimibe produces a beneficial effect on cardiac cachexia in the doxorubicin-induced cardiac cachexia model. Ezetimibe was successful to reduce the levels of inflammatory cytokines, ameliorate the effects on cardiac muscle wasting, lipid levels, fat tissues, and skeletal muscles.