Distinct cysteine residues in Keap1 are required for Keap1-dependent ubiquitination of Nrf2 and for stabilization of Nrf2 by chemopreventive agents and oxidative stress

Neuroprotective potential for mitigating ischemia-reperfusion-induced damage

Reperfusion following cerebral ischemia causes both structural and functional damage to brain tissue and could aggravate a patient's condition; this phenomenon is known as cerebral ischemia-reperfusion injury. Current studies have elucidated the neuroprotective role of the sirtuin protein family (Sirtuins) in modulating cerebral ischemia-reperfusion injury. However, the potential of utilizing it as a novel intervention target to influence the prognosis of cerebral ischemia-reperfusion injury requires additional exploration. In this review, the origin and research progress of Sirtuins are summarized, suggesting the involvement of Sirtuins in diverse mechanisms that affect cerebral ischemia-reperfusion injury, including inflammation, oxidative stress, blood-brain barrier damage, apoptosis, pyroptosis, and autophagy. The therapeutic avenues related to Sirtuins that may improve the prognosis of cerebral ischemia-reperfusion injury were also investigated by modulating Sirtuins expression and affecting representative pathways, such as nuclear factor-kappa B signaling, oxidative stress mediated by adenosine monophosphate-activated protein kinase, and the forkhead box O. This review also summarizes the potential of endogenous substances, such as RNA and hormones, drugs, dietary supplements, and emerging therapies that regulate Sirtuins expression. This review also reveals that regulating Sirtuins mitigates cerebral ischemia-reperfusion injury when combined with other risk factors. While Sirtuins show promise as a potential target for the treatment of cerebral ischemia-reperfusion injury, most recent studies are based on rodent models with circadian rhythms that are distinct from those of humans, potentially influencing the efficacy of Sirtuins-targeting drug therapies. Overall, this review provides new insights into the role of Sirtuins in the pathology and treatment of cerebral ischemia-reperfusion injury.

Gene network analysis combined with preclinical studies to identify and elucidate the mechanism of action of novel irreversible Keap1 inhibitor for Parkinson's disease

The cysteine residues of Keap1 such as C151, C273, and C288 are critical for its repressor activity on Nrf2. However, to date, no molecules have been identified to covalently modify all three cysteine residues for Nrf2 activation. Hence, in this study, our goal is to discover new Keap1 covalent inhibitors that can undergo a Michael addition with all three cysteine residues. The Keap1's intervening region was modeled using Modeller v10.4. Covalent docking and binding free energy were calculated using CovDock. Molecular dynamics (MD) was performed using Desmond. Various in-vitro assays were carried out to confirm the neuroprotective effects of the hit molecule in 6-OHDA-treated SH-SY5Y cells. Further, the best hit was evaluated in vivo for its ability to improve rotenone-induced postural instability and cognitive impairment in male rats. Finally, network pharmacology was used to summarize the complete molecular mechanism of the hit molecule. Chalcone and plumbagin were found to form the necessary covalent bonds with all three cysteine residues. However, MD analysis indicated that the binding of plumbagin is more stable than chalcone. Plumbagin displayed neuroprotective effects in 6-OHDA-treated SH-SY5Y cells at concentrations 0.01 and 0.1 μM. Plumbagin at 0.1 µM had positive effects on reactive oxygen species formation and glutathione levels. Plumbagin also improved postural instability and cognitive impairment in rotenone-treated male rats. Our network analysis indicated that plumbagin could also improve dopamine signaling. Additionally, plumbagin could exhibit anti-oxidant and anti-inflammatory activity through the activation of Nrf2. Cumulatively, our study suggests that plumbagin is a novel Keap1 covalent inhibitor for Nrf2-mediated neuroprotection in PD.

The clinical-grade CBP/ p300 inhibitor CCS1477 represses the global NRF2-dependent cytoprotective transcription program and re-sensitizes cancer cells to chemotherapeutic drugs

Constitutive activation of NRF2 provides a selective advantage to malignant tumour clones through the hijacking of the NRF2-dependent cytoprotective transcriptional program, which allows the cancer cells to survive and thrive in the chemically stressful tumour niche, whilst also providing resistance to anti-cancer drugs due to the upregulation of xenobiotic metabolizing enzymes and drug efflux pumps. Through a small-molecule epigenetic screen carried out in KEAP1 mutant lung cancer cells, in this study, we identified CCS1477 (Inobrodib) to be an inhibitor of the global NRF2-dependent transcription program. Mechanistically, CCS1477 is able to repress NRF2's cytoprotective response through the inhibition of its obligate transcriptional activator partner CBP/p300. Importantly, in addition to repressing NRF2-dependent anti-oxidative stress and xenobiotic metabolizing enzyme gene expression, CCS1477 treatment is also able to reverse the chemoresistance phenotype and re-sensitize NRF2-activated tumour cells to anti-cancer drugs. Furthermore, in co-culture experiments of KEAP1 mutant cancer cells with primary human T cells, CCS1477 treatment suppressed the acquisition of the T cell exhaustion transcriptional state, which should function to augment the anti-cancer immune response. Thus, CCS1477-mediated inhibition of CBP/p300 represents a novel therapeutic strategy with which to target the currently untreatable tumours with aberrant NRF2 activation.

PIP5K1A Suppresses Ferroptosis and Induces Sorafenib Resistance by Stabilizing NRF2 in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related mortality worldwide. Ferroptosis, an iron-dependent form of programmed cell death driven by lipid peroxidation, has emerged as a promising strategy for cancer treatment. However, the development of ferroptosis resistance limits the efficacy of such treatments. This study reports that phosphatidylinositol 4-phosphate 5-kinase 1 alpha (PIP5K1A) promotes HCC tumorigenesis and predicts poor prognosis in HCC patients. Knockdown of PIP5K1A enhances lipid peroxidation and increases sensitivity to sorafenib-induced ferroptosis by inhibiting the activation of downstream ferroptosis-related genes regulated by nuclear factor erythroid-2-related factor 2 (NRF2). Mechanistically, PIP5K1A competitively binds to the Kelch domain of Kelch-like ECH-associated protein 1 in a kinase-independent manner, leading to NRF2 escaping from ubiquitination degradation, thereby promoting NRF2-dependent transcription and suppressing ferroptosis. Furthermore, ISA-2011B, a PIP5K1A-specific inhibitor, effectively inhibits HCC growth and sensitized HCC cells to sorafenib. In conclusion, PIP5K1A is a promising therapeutic target for improving the efficacy of sorafenib and other ferroptosis inducers in HCC.

Phenethyl Isothiocyanate (PEITC) interaction with Keap1 activates the Nrf2 pathway and inhibits lipid accumulation in adipocytes

Phenethyl isothiocyanate (PEITC) has been recognized for its potential effects in various human diseases. However, the impact of PEITC on adipocyte differentiation and its underlying molecular mechanisms is not well understood. This study investigates the effects of PEITC on adipocyte differentiation and elucidates the molecular mechanisms involved in Nrf2 activation. The effects of PEITC on adipocyte differentiation were assessed in C3H10T1/2 and 3T3-L1 cells. Nrf2-induced effects by PEITC were examined in Nrf2 knockout (KO) MEF and Keap1 KO H1299 cells. The interaction between PEITC and Keap1 was evaluated using thermal shift assays and Co-immunoprecipitation experiments. Reconstitution of cysteine mutants of Keap1 in Keap1 KO cells was used to elucidate a critical amino acid for the PEITC-induced Nrf2 stabilization. The initial stages of adipogenesis were crucial for PEITC's anti-adipogenic effects in C3H10T1/2 and 3T3-L1 cells. PEITC increased Nrf2 protein expression, but this induction was absent in Keap1 KO cells. Thermal shift assays with the purified BTB domain of Keap1 confirmed a direct interaction with PEITC. Re-expression of Keap1 in Keap1 KO cells showed that the cysteine residue at position 151 is essential for PEITC-induced Nrf2 expression and the disruption of the Nrf2-Keap1 complex. PEITC was found to activate Nrf2-mediated gene expression and inhibit adipocyte differentiation, at least partially, through Nrf2-dependent mechanisms. This study confirms the anti-adipogenic effects of PEITC. Mechanistic investigations demonstrate that PEITC interacts with Keap1 and that the cysteine residue (C151) of Keap1 is critical for PEITC's effects on Nrf2 activation.

Molecular Targets of Oxidative Stress: Focus on Nuclear Factor Erythroid 2-Related Factor 2 Function in Leukemia and Other Cancers

Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor that plays a central role in regulating cellular responses to oxidative stress. It governs the expression of a broad range of genes involved in antioxidant defense, detoxification, metabolism, and other cytoprotective pathways. In normal cells, the transient activation of Nrf2 serves as a protective mechanism to maintain redox homeostasis. However, the persistent or aberrant activation of Nrf2 in cancer cells has been implicated in tumor progression, metabolic reprogramming, and resistance to chemotherapy and radiotherapy. These dual roles underscore the complexity of Nrf2 signaling and its potential as a therapeutic target. A deeper understanding of Nrf2 regulation in both normal and malignant contexts is essential for the development of effective Nrf2-targeted therapies. This review provides a comprehensive overview of Nrf2 regulation and function, highlighting its unique features in cancer biology, particularly its role in metabolic adaptation and drug resistance. Special attention is given to the current knowledge of Nrf2's involvement in leukemia and emerging strategies for its therapeutic modulation.

Keap1-independent Nrf2 regulation: A novel therapeutic target for treating kidney disease

The transcription factor NF-E2-related factor 2 (Nrf2) is a master regulator of antioxidant responses in mammals, where it plays a critical role in detoxification, maintaining cellular homeostasis, combating inflammation and fibrosis, and slowing disease progression. Kelch-like ECH-associated protein 1 (Keap1), an adaptor subunit of Cullin 3-based E3 ubiquitin ligase, serves as a critical sensor of oxidative and electrophilic stress, regulating Nrf2 activity by sequestering it in the cytoplasm, leading to its proteasomal degradation and transcriptional repression. However, the clinical potential of targeting the Keap1-dependent Nrf2 regulatory pathway has been limited. This is evidenced by early postnatal lethality in Keap1 knockout mice, as well as significant adverse events after pharmacological blockade of Keap1 in human patients with Alport syndrome as well as in those with type 2 diabetes mellitus and chronic kidney disease. The exact underlying mechanisms remain elusive, but may involve non-specific and systemic activation of the Nrf2 antioxidant response in both injured and normal tissues. Beyond Keap1-dependent regulation, Nrf2 activity is modulated by Keap1-independent mechanisms, including transcriptional, epigenetic, and post-translational modifications. In particular, GSK3β has emerged as a critical convergence point for these diverse signaling pathways. Unlike Keap1-dependent regulation, GSK3β-mediated Keap1-independent Nrf2 regulation does not affect basal Nrf2 activity but modulates its response at a delayed/late phase of cellular stress. This allows fine-tuning of the inducibility, magnitude, and duration of the Nrf2 response specifically in stressed or injured tissues. As one of the most metabolically active organs, the kidney is a major source of production of reactive oxygen and nitrogen species and also a vulnerable organ to oxidative damage. Targeting the GSK3β-mediated Nrf2 regulatory pathway represents a promising new approach for the treatment of kidney disease.

Distinct Stress Regulators in the CRL Family: Emerging Roles of F-Box Proteins: Cullin-RING Ligases and Stress-Sensing

Cullin-RING ligases (CRLs) are central regulators of environmental and cellular stress responses, orchestrating diverse processes through the ubiquitination of substrate proteins. As modular complexes, CRLs employ substrate-specific adaptors to target proteins for degradation and other ubiquitin-mediated processes, enabling dynamic adaptation to environmental cues. Recent advances have highlighted the largest CRL subfamily SCF (Skp1-cullin-F-box) in environmental sensing, a role historically underappreciated for SCF ubiquitin ligases. Notably, emerging evidence suggests that the F-box domain, a 50-amino acid motif traditionally recognized for mediating protein-protein interactions, can act as a direct environmental sensor due to its ability to bind heavy metals. Despite these advances, the roles of many CRL components in environmental sensing remain poorly understood. This review provides an overview of CRLs in stress response regulation and emphasizes the emerging functions of F-box proteins in environmental adaptation.

Endoplasmic reticulum stress inhibition preserves mitochondrial function and cell survival during the early onset of isoniazid-induced oxidative stress

A comprehensive understanding of isoniazid (INH)-mediated hepatotoxic effects is essential for developing strategies to predict and prevent severe liver toxicity in tuberculosis treatment. In this study, we used multi-omics profiling in vitro to investigate the toxic effects of INH, revealing significant involvement of endoplasmic reticulum (ER) stress, mitochondrial impairment, redox imbalance, and altered metabolism. Additional analysis using transcriptomics data from repeated time-course INH treatments on human hepatic microtissues revealed that cellular responses to ER stress and oxidative stress happened prior to disturbances in mitochondrial complexes. Mechanistic validation studies using time-lapse measurements of cytosolic and mitochondrial reactive oxygen species (ROS) revealed that INH initially triggered cytosolic ROS increasement and Nrf2 signaling pathway activation before mitochondrial ROS accumulation. Molecular imaging showed that INH subsequently disrupted mitochondrial function by impairing respiratory complexes I-IV and caused mitochondrial membrane proton leakage without affecting mitochondrial complex V, leading to mitochondrial depolarization and reduced ATP production. These disturbances enhanced mitochondrial fission and mitophagy. Our findings highlight the potential of inhibiting ER stress during early INH exposure to mitigate cytosolic and mitochondrial oxidative stress. We also revealed the critical role of Nrf2 signaling in protecting hepatocytes under INH-induced oxidative stress by maintaining redox homeostasis and enabling metabolic reprogramming through regulating antioxidant gene expression and cellular lipid abundance. Alternative antioxidant pathways, including selenocompound metabolism, HIF-1 signaling, and the pentose phosphate pathway, also responded to INH-induced oxidative stress. Collectively, our study emphasizes the importance of ER stress, redox imbalance, metabolic changes, and mitochondrial dysfunction that underlie INH-induced hepatotoxicity.

The Keap1/Nrf2/ARE/HO-1 axis in epilepsy: Crosstalk between oxidative stress and neuroinflammation

Epilepsy is a complex neurological disorder characterized by recurrent seizures, which are driven by multifaceted pathophysiological mechanisms, including oxidative stress and neuroinflammation. Despite advancements in anti-seizure medications (ASMs), a significant proportion of patients remain resistant to treatment, highlighting the need for novel therapeutic strategies. This review focuses on the Kelch-like ECH-associated protein 1 (Keap1) / Nuclear factor erythroid 2-related factor 2 (Nrf2) / Antioxidant Response Element (ARE) / Heme Oxygenase-1 (HO-1) axis as a promising target for neuroprotection in epilepsy. We explored the intricate interactions between Keap1 and Nrf2 under homeostatic conditions and how oxidative stress disrupts this balance, triggering Nrf2 activation. This review details the subsequent process of Nrf2 nuclear translocation, its binding to AREs, and the induction of cytoprotective gene expression, which collectively orchestrate a robust cellular defense response. Special emphasis is placed on HO-1, a key effector of Nrf2-mediated neuroprotection, highlighting its enzymatic function and protective mechanisms, including antioxidant, anti-inflammatory, and anti-apoptotic effects. Additionally, the review examines HO-1's role in mitigating seizure-induced neuronal damage. However, challenges remain, including variability in therapeutic responses, gaps in long-term clinical validation, and the need for standardized protocols. Future research should focus on biomarkers for personalized treatment, advanced imaging, and genetic tools to explore the Keap1/Nrf2/ARE/HO-1 axis in greater depth. Future studies should focus on overcoming the challenges of translating preclinical findings into clinical applications and exploring the long-term effects of targeting this pathway in epilepsy treatment.

Major Oxidative and Antioxidant Mechanisms During Heat Stress-Induced Oxidative Stress in Chickens

Heat stress (HS) is one of the most important stressors in chickens, and its adverse effects are primarily caused by disturbing the redox homeostasis. An increase in electron leakage from the mitochondrial electron transport chain is the major source of free radical production under HS, which triggers other enzymatic systems to generate more radicals. As a defense mechanism, cells have enzymatic and non-enzymatic antioxidant systems that work cooperatively against free radicals. The generation of free radicals, particularly the reactive oxygen species (ROS) and reactive nitrogen species (RNS), under HS condition outweighs the cellular antioxidant capacity, resulting in oxidative damage to macromolecules, including lipids, carbohydrates, proteins, and DNA. Understanding these detrimental oxidative processes and protective defense mechanisms is important in developing mitigation strategies against HS. This review summarizes the current understanding of major oxidative and antioxidant systems and their molecular mechanisms in generating or neutralizing the ROS/RNS. Importantly, this review explores the potential mechanisms that lead to the development of oxidative stress in heat-stressed chickens, highlighting their unique behavioral and physiological responses against thermal stress. Further, we summarize the major findings associated with these oxidative and antioxidant mechanisms in chickens.

The Ancestral KEAP1-NRF Pathway in Amphioxus Branchiostoma japonicum: Implications for the Evolution of Antioxidant Defense System

The Kelch-like ECH-associated protein 1 (KEAP1)/Nuclear factor E2-related factor 2 (NRF2) pathway is a key mechanism that responds to oxidative stress and xenobiotic stimuli in vertebrates. However, knowledge of its evolutionary origins remains limited. In this study, we identify the ancestral homologues of KEAP1 and NRF (BjKEAP1 and BjNRF) in cephalochordate amphioxus (Branchiostoma japonicum). BjNRF uniquely combines the feature domains of vertebrates NRF1 and NRF2, marking it as an evolutionary intermediate. High expression levels of Bjkeap1 and Bjnrf in the gill, hepatic cecum, and intestine highlight their roles in environmental defense at key interface tissues. Functional studies reveal that BjKEAP1 regulates the cytoplasmic localization of BjNRF. Typical NRF2 activator sulforaphane (SFN) induces its nuclear translocation and significantly elevates the transcriptional expression of BjNRF and phase II detoxification enzymes. Moreover, exposure to the environmental toxin Benzo[a]pyrene (BaP) activates this stress response system. These findings bridge critical gaps in our understanding of this pathway in basal chordates and offer new insights into the evolutionary trajectory of the KEAP1-NRF system. Furthermore, this study highlights crucial implications for the conservation of amphioxus in deteriorating marine environments.

Considerations for antibody-based detection of NRF2 in human cells

Based on the knockdown and overexpression experiments, it is accepted that in Tris-glycine SDS-PAGE human NRF2 migrates above 100 kDa, depending on the percentage of the gel. In 8 % Tris-glycine gel, monoclonal anti-NRF2 antibodies detect NRF2 signal as three bands migrating between 100 and 130 kDa. Here we used mass spectrometry to identify proteins immunoprecipitated by anti-NRF2 antibodies migrating in this range under steady state, upon NRF2 activator tert-BHQ and after translation inhibition with emetine. Our results show that three commercial monoclonal antibodies with epitopes in the center and in the C-terminus of NRF2 also bind calmegin, an ER-residing chaperone, that co-migrates with NRF2 in SDS-PAGE and gives stronger signal in western blot than NRF2. Calmegin has a much longer half life than NRF2 and resides in the cytoplasm, which differentiates it from NRF2. The most specific anti-NRF2 antibody in western blot, Cell Signaling Technology clone E5F1 is also specific in staining nuclear NRF2 in immunofluorescence. Other antibodies, that recognize calmegin in western blot, still can be specific for nuclear NRF2 in immunofluorescence, but require prior validation with NRF2 knockdown or knockout. These results appeal for caution and consideration when analyzing and interpreting results from antibody-based NRF2 detection.

Inhibition of MALAT1 facilitates ROS accumulation via the Keap1/HO-1 pathway to enhance photodynamic therapy in secondary hyperparathyroidism

The prevalence of secondary hyperparathyroidism (SHPT) in advanced chronic kidney disease (CKD) exceeds 80 %. Our previous study indicated that photodynamic therapy (PDT) has potential for treating SHPT. Long noncoding RNA (lncRNA) is involved in various oxidative stress and apoptotic processes, but the molecular mechanism remains unreported. In this study, we found that PDT induced apoptosis in SHPT through reactive oxygen species (ROS) accumulation. The expression of metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) and heme oxygenase 1 (HO-1) within SHPT was upregulated after PDT. Inhibition of MALAT1 increased PDT-induced ROS, which promoted the apoptosis. Pearson correlation analysis confirmed that there was a positive correlation between MALAT1 and HO-1, and MALAT1 inhibition down-regulated HO-1, whereas concomitant overexpression of HO-1 was able to eliminate the PDT-induced ROS and inhibit apoptosis. The direct binding of MALAT1 to Kelch-like ECH-associated protein 1 (Keap1) protein was confirmed by high-throughput sequencing, RNA pulldown, silver staining and western blotting assays. Si-Keap1 was able to rescue the down-regulation of HO-1 caused by MALAT1 inhibition, restoring the elimination of ROS by HO-1 and attenuating the effect of PDT. In addition, PDT effectively reduced parathyroid hormone (PTH) secretion in SHPT rats, and this effect was further enhanced in combination with MALAT1 inhibitors. Overall, MALAT1 activates downstream HO-1 expression by binding to Keap1, thereby reducing ROS and inhibiting apoptosis, which in turn mediates PDT resistance in SHPT. Inhibition of MALAT1 significantly enhanced the efficacy of PDT, suggesting a potential therapeutic target for improving PDT for SHPT outcomes.

Health position paper and redox perspectives - Bench to bedside transition for pharmacological regulation of NRF2 in noncommunicable diseases

Nuclear factor erythroid 2-related factor 2 (NRF2) is a redox-activated transcription factor regulating cellular defense against oxidative stress, thereby playing a pivotal role in maintaining cellular homeostasis. Its dysregulation is implicated in the progression of a wide array of human diseases, making NRF2 a compelling target for therapeutic interventions. However, challenges persist in drug discovery and safe targeting of NRF2, as unresolved questions remain especially regarding its context-specific role in diseases and off-target effects. This comprehensive review discusses the dualistic role of NRF2 in disease pathophysiology, covering its protective and/or destructive roles in autoimmune, respiratory, cardiovascular, and metabolic diseases, as well as diseases of the digestive system and cancer. Additionally, we also review the development of drugs that either activate or inhibit NRF2, discuss main barriers in translating NRF2-based therapies from bench to bedside, and consider the ways to monitor NRF2 activation in vivo.

Patenting perspective on Keap1 inhibitors (2019-2024)

INTRODUCTION

Kelch-like ECH-associated protein 1 (Keap1), an E3 ligase negatively regulating the nuclear factor erythroid 2-related factor 2 (Nrf2), has emerged as an auspicious drug target for treating ailments associated with oxidative stress and inflammation. Discovery of Keap1 inhibitors have attracted significant interest.

AREAS COVERED

This review covers patents on Keap1 inhibitors from 2019 to 2024, providing a comprehensive analysis of their structural characteristics, optimization strategies, pharmacological properties and clinical progress.

EXPERT OPINION

Extensive efforts have been devoted to enhance potency and drug-like properties of Keap1 inhibitors. Strategies such as ROS-cleavable prodrug design, bivalent inhibition and PROTACs are emerging. As the range of drug types and applications expands, Keap1 inhibitors are becoming a sagacious option for disease treating.

Rice bran extract ameliorate heavy metal mixture induced hippocampal toxicity via inhibiting oxido-inflammatory damages and modulating Hmox-1/BDNF/Occludin/Aβ40/Aβ42 in rats

The hippocampus executes the integration of memory and spatial learning information. This study evaluated the effect of rice bran extract (RBE) on heavy metal mixture (MM) induced hippocampal toxicity and its underlying mechanism in albino rats. Thirty five rats were exposed to MM alone at Pb 20 mg/kg, Al 35 mg/kg, and Mn 0.564 mg/kg body weight or co-exposed with RBE at 125, 250 and 500 mg/kg body weight, 125 RBE mg/kg b.wt only, and 500 RBE mg/kg b.wt only 5 days a wk for 13 wk (90 days). Subsequently, oxidative stress, inflammation (cyclooxygenase-2) and caspase-3, amyloid precursor proteins (Aβ40 and Aβ42), HMOX-1, occludin and BDNF and transcription factor Nrf-2 in the hippocampus were investigated. MM treatment resulted in significantly higher escape latency time than both the control and MM plus RBE group. MM exposure induced increased oxidative stress, inflammation resulting in enhanced hippocampal apoptosis. MM significantly increased bioaccumulation of Pb, Al, and Pb; increased caspase-3, Nrf-2, Aβ40 and Aβ42 and significantly decreased occludin, BDNF, HMOX-1 when compared with the control. All these effects were reversed by RBE. Collectively, RBE ameliorated MM - induced oxidative stress, neuro-inflammation and hippocampal apoptosis via attenuation of oxidative damages of cellular constituents, neuronal inflammation and subsequent down regulation of amyloid precursor proteins Aβ40, Aβ42 and up regulation of occludin, BDNF, HMOX-1 protein expression via Nrf-2 dependent pathways to abrogate hippocampal toxicity associated with spatial learning and memory deficits.

New insights into reductive stress responses and its clinical relation in cancer

Cells are susceptible to both oxidative and reductive stresses, with reductive stress being less studied and potentially therapeutic in cancer. Reductive stress, characterized by an excess of reducing equivalents exceeding the activity of endogenous oxidoreductases, can lead to an imbalance in homeostasis, causing an increase in reactive oxygen species induction, affecting cellular antioxidant load and flux. Unlike oxidative stress, reductive stress has been understudied and poorly understood, and there is still much to learn about its mechanisms in cancer, its therapeutic potential, and how cancer cells react to it. Changes in redox balance and interference with redox signaling are linked to cancer cell growth, metastasis, and resistance to chemotherapy and radiation. Overconsumption of reducing equivalents can reduce metabolism, alter protein disulfide bond formation, disrupt mitochondrial homeostasis, and disrupt cancer cell signaling pathways. Novel approaches to delivering or using cancer medicines and techniques to influence redox biology have been discovered. Under reductive stress, cancer cells may coordinate separate pools of redox pairs, potentially impacting biology.

Scutellarin Alleviates Bone Marrow Mesenchymal Stromal Cellular Senescence via the Ezh2-Nrf2 Signalling Axis in Diabetes-Induced Bone Loss

Currently, there is no specific treatment for diabetes-induced osteoporosis (DOP). Our study identified diabetes-induced cellular senescence, marked by elevated activity of senescence-associated β-galactosidase. Targeting senescent cells holds promise for osteoporosis treatment. We demonstrated that scutellarin (SCU) effectively mitigated bone loss in DOP mice, and co-treatment with SCU significantly reduced diabetes-induced senescence in LepR+MSCs. Furthermore, our research highlighted the role of Nrf2 in SCU's anti-senescence effects on bone. The deletion of Nrf2 impaired SCU's ability to alleviate DOP. Mechanistically, SCU enhances Ezh2 expression and increases H3K27me3 activity at the Keap1 promoter region, leading to Keap1 repression and enhanced Nrf2-ARE signalling. Additionally, SCU notably inhibited cellular senescence and diabetes-related osteoporosis, these effects were significantly reduced in Ezh2LepRcre conditional knockout models. These findings suggest that the Ezh2-Nrf2 signalling axis is crucial for mediating SCU's beneficial effects in this context. Overall, our discoveries provide insights into the mechanisms underlying DOP and propose a potential preventive strategy for this condition.

Impact of Co-mutations and Transcriptional Signatures in Non-Small Cell Lung Cancer Patients Treated with Adagrasib in the KRYSTAL-1 Trial

PURPOSE

KRAS inhibitors are revolutionizing the treatment of non-small cell lung cancer (NSCLC), but clinico-genomic determinants of treatment efficacy warrant continued exploration.

EXPERIMENTAL DESIGN

Patients with advanced KRASG12C-mutant NSCLC treated with adagrasib [KRYSTAL-1 (NCT03785249)] were included in the analysis. Pretreatment next-generation sequencing data were collected per protocol. HTG EdgeSeq Transcriptome Panel was used for gene expression profiling. Clinical endpoints included objective response, progression-free survival (PFS), and overall survival (OS). KRASG12C-mutant NSCLC cell lines and xenograft models were used for sensitivity analyses and combination drug screens.

RESULTS

KEAP1 MUT and STK11MUT were associated with shorter survival to adagrasib [KEAP1: PFS 4.1 vs. 9.9 months, HR 2.7, P < 0.01; OS 5.4 vs. 19.0 months, HR 3.6, P < 0.01; STK11: PFS 4.2 vs. 11.0 months, HR 2.2, P < 0.01; OS 9.8 months vs. not reached (NR), HR 2.6, P < 0.01]. KEAP1WT/STK11WT status identified adagrasib-treated patients with significantly longer PFS (16.9 months) and OS (NR). Preclinical analyses further validate the association between KEAP1 loss of function and adagrasib resistance. Adagrasib and mTOR inhibitor combinations produced higher treatment efficacy in NSCLC models harboring STK11 and KEAP1 co-mutations. NRF2HIGH signaling was associated with shorter survival to adagrasib (PFS: 4.2 vs. 8.4 months, HR 2.0, P = 0.02; OS: 6.5 vs. 19.0 months, HR 2.8, P < 0.01) even in patients with KEAP1WT NSCLC. KEAP1WT/STK11WT/NRF2LOW status identified patients-32%-with longer survival to adagrasib (PFS 12.0 vs. 4.2 months, HR 0.2, P < 0.01; OS NR vs. 8.0 months, HR 0.1, P < 0.01).

CONCLUSIONS

KEAP1, STK11, and NRF2 status define patients with KRASG12C-mutant NSCLC with markedly distinct outcomes to adagrasib. These results further support the use of genomic features-mutational and nonmutational-for the treatment selection of patients with KRASG12C-mutant NSCLC.

The Role of Hydrogen Sulfide in the Regulation of the Pulmonary Vasculature in Health and Disease

The gasotransmitter hydrogen sulfide (H2S; also termed sulfide) generally acts as a vasodilator in the systemic vasculature but causes a paradoxical constriction of pulmonary arteries (PAs). In light of evidence that a fall in the partial pressure in oxygen (pO2) increases cellular sulfide levels, it was proposed that a rise in sulfide in pulmonary artery smooth muscle cells (PASMCs) is responsible for hypoxic pulmonary vasoconstriction, the contraction of PAs which develops rapidly in lung regions undergoing alveolar hypoxia. In contrast, pulmonary hypertension (PH), a sustained elevation of pulmonary artery pressure (PAP) which can develop in the presence of a diverse array of pathological stimuli, including chronic hypoxia, is associated with a decrease in the expression of sulfide -producing enzymes in PASMCs and a corresponding fall in sulfide production by the lung. Evidence that PAP in animal models of PH can be lowered by administration of exogenous sulfide has led to an interest in using sulfide-donating agents for treating this condition in humans. Notably, intracellular H2S exists in equilibrium with other sulfur-containing species such as polysulfides and persulfides, and it is these reactive sulfur species which are thought to mediate most of its effects on cells through persulfidation of cysteine thiols on proteins, leading to changes in function in a manner similar to thiol oxidation by reactive oxygen species. This review sets out what is currently known about the mechanisms by which H2S and related sulfur species exert their actions on pulmonary vascular tone, both acutely and chronically, and discusses the potential of sulfide-releasing drugs as treatments for the different types of PH which arise in humans.

USP37 as a novel regulator of NRF2 protein stability and chemoresistance in HCC

Chemoresistance is a prevalent issue in cancer, resulting in a poor prognosis. The transcription factor nuclear factor (erythroid-derived 2)-like 2 (NRF2), a key regulator in cellular antioxidant responses, is implicated in cell survival, proliferation, and chemoresistance. It represents a promising target for treating Hepatocellular carcinoma (HCC). The NRF2 activity has been recently revealed to be controlled by the ubiquitination process mediated by the KEAP1-CUL3 E3 ligase, highlighting the importance of deubiquitination regulation. However, the specific deubiquitinase (DUB) responsible for NRF2 in liver cancer remains unclear. In this study, we demonstrate that Ubiquitin-Specific Protease 37 (USP37) acts as a novel regulator of NRF2 protein. Mechanistically, USP37 modulates the stability of NRF2 through enzymatic activity-dependent deubiquitination. Additionally, USP37 interacts with NRF2 and facilitates its deubiquitination. Elevated USP37 levels were associated with higher levels of NRF2 protein in samples from human patients. Importantly, the knockdown of USP37 results in increased NRF2 degradation and enhances cellular sensitivity to chemotherapy. Overall, our findings manifested the significant involvement of the USP37-NRF2 axis in regulating therapeutic interventions for HCC.

Thirty years of NRF2: advances and therapeutic challenges

Over the last 30 years, NRF2 has evolved from being recognized as a transcription factor primarily involved in redox balance and detoxification to a well-appreciated master regulator of cellular proteostasis, metabolism and iron homeostasis. NRF2 plays a pivotal role in diverse pathologies, including cancer, and metabolic, inflammatory and neurodegenerative disorders. It exhibits a Janus-faced duality, safeguarding cellular integrity in normal cells against environmental insults to prevent disease onset, whereas in certain cancers, constitutively elevated NRF2 levels provide a tumour survival advantage, promoting progression, therapy resistance and metastasis. Advances in understanding the mechanistic regulation of NRF2 and its roles in human pathology have propelled the investigation of NRF2-targeted therapeutic strategies. This Review dissects the mechanistic intricacies of NRF2 signalling, its cross-talk with biological processes and its far-reaching implications for health and disease, highlighting key discoveries that have shaped innovative therapeutic approaches targeting NRF2.

Targeting KEAP1-mediated IKKβ degradation strategy for colitis-associated colorectal carcinogenesis: The potential of xanthohumol

In colitis-associated colorectal cancer (CAC), the NF-κB pathway, especially IKKβ, drives inflammation and cancer progression. However, no IKKβ inhibitors have been approved due to compensatory mechanisms. The challenge is to develop an anti-tumor agent that effectively targets IKKβ while overcoming these compensatory pathways. We conducted in vitro and in vivo experiments to evaluate the anti-cancer effects of synthesized xanthohumol (XN) targeting IKKβ. CAC was induced in mice, followed by XN treatment. Histological and molecular analyses, including cell viability assays, immunoblotting, and qRT-PCR, were performed. Human colon cancer cell lines were also used to investigate IKKβ's role. RNA sequencing revealed elevated IKKβ expression in colorectal cancer human tissues, correlating with poor prognosis. XN significantly reduced adenocarcinoma formation and inflammation in vivo while decreasing IKKβ and NF-κB signaling in both models. XN binds to the C179 residue of IKKβ, inhibiting its activity. Additionally, our findings highlight KEAP1's role as an upstream regulator of IKKβ degradation. XN specifically interacts with the C288 residue of KEAP1, showing triple-binding affinity with IKKβ and KEAP1. These results indicate that XN promotes conditions where KEAP1 facilitates IKKβ degradation.

Down-regulation of Selenoprotein K impairs the proliferation and differentiation of chicken skeletal muscle satellite cells by inhibiting the Nrf2 antioxidant signaling pathway

Skeletal muscle satellite cells (SMSCs) are pivotal for skeletal muscle regeneration post-injury, and their development is intricately influenced by regulatory factors. Selenoprotein K (SELENOK), an endoplasmic reticulum resident selenoprotein, is known for its crucial role in maintaining skeletal muscle redox sensing. However, the specific molecular mechanism of SELENOK in SMSCs remains unclear. In this study, a SELENOK knockdown model was established to delve into its role in SMSCs. The results revealed that SELENOK knockdown hindered SMSCs proliferation and differentiation, as evidenced by the regulation of key proteins such as Pax7, Myf5, CyclinD1, MyoD, and Myf6, and the inhibitory effects were mitigated by N-Acetyl-l-cysteine (NAC). SELENOK knockdown induced oxidative stress, further analyses uncovered that SELENOK knockdown downregulated nuclear transcription factor nuclear erythroid factor 2-like 2 (Nrf2) protein expression while upregulating cytoplasmic kelch-like ECH-associated protein 1 (Keap1) protein expression. SELENOK knockdown impeded Nestin and sequestosome 1/p62 (p62) interaction with Keap1, leading to increased Nrf2 ubiquitination. This prevented Nrf2 transportation from cytoplasm to nucleus mediated by Keap1, ultimately resulting in the downregulation of catalase (CAT), heme oxygenase-1 (HO-1), and glutathione peroxidase 4 (GPX4) protein expression. Notably, SELENOK knockdown-induced inhibition of SMSCs proliferation and differentiation was alleviated by Oltipraz, an activator of the Nrf2 pathway. This study provided novel insights, demonstrating that SELENOK is a key player in SMSCs proliferation and differentiation by influencing the Nrf2 antioxidant signaling pathway.

Regulating Nrf2 activity: ubiquitin ligases and signaling molecules in redox homeostasis

Transcription factor NF-E2 p45-related factor 2 (Nrf2) orchestrates defenses against oxidants and thiol-reactive electrophiles. It is controlled at the protein stability level by several E3 ubiquitin ligases (CRL3Keap1, CRL4DCAF11, SCFβ-TrCP, and Hrd1). CRL3Keap1 is of the greatest importance because it constitutively targets Nrf2 for proteasomal degradation under homeostatic conditions but is prevented from doing so by oxidative stressors. Repression of Nrf2 by CRL3Keap1 is attenuated by SQSTM1/p62, and this is reinforced by phosphorylation of SQSTM1/p62. Repression by SCFβ-TrCP requires phosphorylation of Nrf2 by GSK3, the activity of which is inhibited by PKB/Akt and other kinases. We discuss how Nrf2 activity is controlled by the ubiquitin ligases under different circumstances. We also describe endogenous signaling molecules that inactivate CRL3Keap1 to alleviate stress and restore homeostasis.

Cyclic vinyl sulfones activate NRF2 to protect from oxidative stress-induced programmed necrosis

The NRF2 transcriptional factor is a member of cellular stress response machinery and is activated in response to oxidative stress caused either by cellular homeostasis imbalance or by environmental challenges. NRF2 levels are stringently controlled by rapid and continuous proteasomal degradation. KEAP1 is a specific NRF2 binding protein that acts as a bridge between NRF2 and the E3 ligase Cullin-3. In this study, we examine model cyclic vinyl sulfone derivatives as potential NRF2 activating probes. Previously, we and other authors have found anti-inflammatory properties of these compounds in in vivo models; however, the mechanism of action remained unknown. Here, we show that the naphthohydroquinone derivative LCB1353 efficiently stabilizes NRF2 protein levels and upregulates its target genes. At low 5-10 µM concentrations LCB1353 protects non-small cell lung cancer H1299 cells from ferroptotic death induced by cytotoxic concentrations of RSL3, reducing cell death from 90 % to 5 %. Thus, we suggest that cyclic vinyl sulfones are promising scaffolds for the design of protective molecules for conditions associated with toxic and inflammatory levels of oxidative stress.

Epigallocatechin-3-Gallate Inhibits Oxidative Stress Through the Keap1/Nrf2 Signaling Pathway to Improve Alzheimer Disease

Alzheimer disease (AD) is a common neurodegenerative disease with an intricate pathophysiological mechanism. Oxidative stress has been shown in several investigations as a significant factor in AD progression. For instance, studies have confirmed that oxidative stress inhibition may considerably improve AD symptoms, with potent antioxidants being touted as a possible interventional strategy in the search for AD treatment. Epigallocatechin-3-gallate (EGCG) acts as a natural catechin that has antioxidant effect. It activates the kelch-like epichlorohydrin-associated proteins (Keap1)/nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway to inhibit oxidative stress. The Keap1/Nrf2 signal pathway is not only an upstream signaling target for a variety of antioxidant enzymes, but also minimizes high levels of reactive oxygen species. This report analyzes the antioxidant effect of EGCG in AD, elaborates its specific mechanism of action, and provides a theoretical basis for its clinical application in AD.

Hepatoprotective Effects of Cilnidipine in Cholestatic Liver Disease: Role of FXR and NRF2 Signalling

Background

Bile acid (BA) is a type of cholesterol derivative that has long been established for its crucial role in the breakdown and absorption of fat from food. Cholestasis occurs when the liver fails to transfer BAs to the intestines. Chronic cholestatic diseases can lead to liver cirrhosis.

Objective

Ursodeoxycholic acid (UDCA) treatment is ineffective for certain cholestatic diseases like benign recurrent intrahepatic cholestasis (BRIC), despite increasing the hydrophilic bile acid pool. Moreover, studies indicate that UDCA and other bile acids affect liver cell functions, such as biotransformation through CYP enzymes. In hepatitis B virus transgenic mice, a UDCA-rich diet promoted hepatocyte proliferation and tumor growth. Hepatologists advise against using UDCA in patients with severe obstructive cholangiopathies. Given the foregoing, new medications are required to treat these illnesses.

Methods

Twenty-four male Wistar albino rats were separated into three groups (8 rats for each group): negative control group I, positive control group II (ANIT-induced cholestasis), and treatment group III (Cil and ANIT). The mRNA and protein expression levels of FXR, small heterodimer partner (SHP), bile salt export pump (BSEP), nuclear factor erythroid 2-related factor 2 (NRF2), hepatocyte nuclear factor 1α (HNF1α), sirtuin 1 (SIRT1), NADPH dehydrogenase-quinone-1 (NQO-1), and heme oxygenase-1 (HO-1) were assessed post euthanasia. Additionally, other tissue oxidative stress markers were measured.

Results

Cil significantly increased the mRNA expression levels of FXR, SHP, BSEP, HNF1α, and NRF2 and the protein expression levels of FXR, BSEP, SIRT1, NQO-1, and HO-1 in the treatment group compared with those in the positive control group. Additionally, Cil decreased the oxidative stress level compared with that in the ANIT-treated group.

Conclusion

The results suggest that Cil effectively treats cholestasis by affecting the FXR signaling system and the NRF2 pathway.

Therapeutic Effects of Natural Products in the Treatment of Chronic Diseases: The Role in Regulating KEAP1-NRF2 Pathway

Oxidative stress represents a pivotal mechanism in the pathogenesis of numerous chronic diseases. The Kelch-like ECH-associated protein 1-transcription factor NF-E2 p45-related factor 2 (KEAP1-NRF2) pathway plays a crucial role in maintaining redox homeostasis and regulating a multitude of biological processes such as inflammation, protein homeostasis, and metabolic homeostasis. In this paper, we present the findings of recent studies on the KEAP1-NRF2 pathway, which have revealed that it is aberrantly regulated and induces oxidative stress injury in a variety of diseases such as neurodegenerative diseases, cardiovascular diseases, metabolic diseases, respiratory diseases, digestive diseases, and cancer. Given this evidence, targeting KEAP1-NRF2 represents a highly promising avenue for developing therapeutic strategies for chronic diseases, and thus the development of appropriate therapeutic strategies based on the targeting of the NRF2 pathway has emerged as a significant area of research interest. This paper highlights an overview of current strategies to modulate KEAP1-NRF2, as well as recent advances in the use of natural compounds and traditional Chinese medicine, with a view to providing meaningful guidelines for drug discovery and development targeting KEAP1-NRF2. Additionally, it discusses the challenges associated with harnessing NRF2 as a therapeutic target.

KEAP1-NRF2 Interaction in Cancer: Competitive Interactors and Their Role in Carcinogenesis

An American Cancer Society report estimates the emergence of around 2 million new cancer cases in the US in 2024 [...].

N -Acetyl-Tryptophan in Acute Kidney Injury after Cardiac Surgery

Key Points

Background

Cardiac surgery–associated AKI is a common serious complication after cardiac surgery. Currently, there are no specific pharmacological therapies. Our understanding of its pathophysiology remains preliminary.

Methods

A total of 2504 patients with and without AKI after cardiac surgery were enrolled. High-performance liquid chromatography coupled with mass spectrometry was used for untargeted analysis of metabolites in plasma, identifying significant differential metabolites. Subsequently, a liquid chromatography–tandem mass spectrometry–based approach using isotope-labeled standard addition was performed for targeted analysis of the metabolic marker N-acetyl-tryptophan (NAT). The function of NAT was determined using different kidney injury mouse models and epithelial cellular models. Transcriptome sequencing, surface plasmon resonance, and protein mutation were used to explore the mechanism of NAT on the kidney.

Results

We identified a total of 32 differential metabolites related to AKI occurrence on the basis of a cohort of 1042 patients. Among them, NAT was elevated in plasma of patients with cardiac surgery–associated AKI compared with those who did not develop AKI after cardiac surgery. The higher level of NAT in plasma was confirmed by accurate targeted quantification. NAT exhibited kidney-protective effects in ischemia-reperfusion–, cisplatin-, and unilateral ureteral obstruction–induced kidney injury mouse models. Mechanistically, NAT exerted kidney-protective effects by interacting with Kelch-like ECH-associated protein 1 at 483 and 508 sites, resulting in Nrf2 nuclear translocation and the transcription of proteasome genes, respectively.

Conclusions

NAT plays a key role in kidney protection.

The protective roles of eugenol on type 1 diabetes mellitus through NRF2-mediated oxidative stress pathway

Type 1 diabetes mellitus (T1DM), known as insulin-dependent diabetes mellitus, is characterized by persistent hyperglycemia resulting from damage to the pancreatic β cells and an absolute deficiency of insulin, leading to multi-organ involvement and a poor prognosis. The progression of T1DM is significantly influenced by oxidative stress and apoptosis. The natural compound eugenol (EUG) possesses anti-inflammatory, anti-oxidant, and anti-apoptotic properties. However, the potential effects of EUG on T1DM had not been investigated. In this study, we established the streptozotocin (STZ)-induced T1DM mouse model in vivo and STZ-induced pancreatic β cell MIN6 cell model in vitro to investigate the protective effects of EUG on T1DM, and tried to elucidate its potential mechanism. Our findings demonstrated that the intervention of EUG could effectively induce the activation of nuclear factor E2-related factor 2 (NRF2), leading to an up-regulation in the expressions of downstream proteins NQO1 and HMOX1, which are regulated by NRF2. Moreover, this intervention exhibited a significant amelioration in pancreatic β cell damage associated with T1DM, accompanied by an elevation in insulin secretion and a reduction in the expression levels of apoptosis and oxidative stress-related markers. Furthermore, ML385, an NRF2 inhibitor, reversed these effects of EUG. The present study suggested that EUG exerted protective effects on pancreatic β cells in T1DM by attenuating apoptosis and oxidative stress through the activation of the NRF2 signaling pathway. Consequently, EUG holds great promise as a potential therapeutic candidate for T1DM.

Heat stress induces oxidative stress and activates the KEAP1-NFE2L2-ARE pathway in reproduction-related cells

Heat stress negatively affects the reproductive function of in animals and humans. Although a relationship between heat and oxidative stress has been suggested, the underlying mechanism has not been sufficiently examined in reproduction-related cells. Therefore, we aimed to investigate whether heat stress induces oxidative stress using a variety of reproduction-related cells including bovine placental and cumulus-granulosa cells, human cell lines derived from cervical and endometrial cancers, and fibroblasts derived from endometrium. Quantitative polymerase chain reaction analysis showed that the expression levels of representative heat and oxidative stress-related genes were significantly increased in cells cultured at high temperatures compared with those in cells cultured at basal temperatures. Moreover, luciferase reporter assays showed that the reporter activity of the heat shock element and antioxidant responsive element (ARE) was increased in cells cultured at high temperatures compared with that in cells cultured at basal temperatures. Furthermore, the stability of nuclear factor erythroid 2 like 2 (NFE2L2), a master regulator of the cellular stress response, increased under high temperatures. Point mutations in Kelch-like ECH-associated protein 1 (KEAP1) cysteine residues reduced the luciferase activity. Our results suggest that heat stress induces oxidative stress and that the KEAP1-NFE2L2-ARE pathway may play a protective role in reproduction-related cells against heat stress.

Harshly Oxidized Activated Charcoal Enhances Protein Persulfidation with Implications for Neurodegeneration as Exemplified by Friedreich's Ataxia

Harsh acid oxidation of activated charcoal transforms an insoluble carbon-rich source into water-soluble, disc structures of graphene decorated with multiple oxygen-containing functionalities. We term these pleiotropic nano-enzymes as "pleozymes". A broad redox potential spans many crucial redox reactions including the oxidation of hydrogen sulfide (H2S) to polysulfides and thiosulfate, dismutation of the superoxide radical (O2-*), and oxidation of NADH to NAD+. The oxidation of H2S is predicted to enhance protein persulfidation-the attachment of sulfur to cysteine residues. Persulfidated proteins act as redox intermediates, and persulfidation protects proteins from irreversible oxidation and ubiquitination, providing an important means of signaling. Protein persulfidation is believed to decline in several neurological disorders and aging. Importantly, and consistent with the role of persulfidation in signaling, the master antioxidant transcription factor Nrf2 is regulated by Keap1's persulfidation. Here, we demonstrate that pleozymes increased overall protein persulfidation in cells from apparently healthy individuals and from individuals with the mitochondrial protein mutation responsible for Friedreich's ataxia. We further find that pleozymes specifically enhanced Keap1 persulfidation, with subsequent increased accumulation of Nrf2 and Nrf2's antioxidant targets.

DDO1002, an NRF2-KEAP1 inhibitor, improves hematopoietic stem cell aging and stress response

Oxidative stress diminishes the functionality of hematopoietic stem cells (HSCs) as age advances, with heightened reactive oxygen species (ROS) levels exacerbating DNA damage, cellular senescence, and hematopoietic impairment. DDO1002, a potent inhibitor of the NRF2-KEAP1 pathway, modulates the expression of antioxidant genes. Yet, the extent to which it mitigates hematopoietic decline post-total body irradiation (TBI) or in the context of aging remains to be elucidated. Our study has elucidated the role of DDO1002 in modulating NRF2 activity, which, in turn, activates the NRF2-driven antioxidant response element (ARE) signaling cascade. This activation can diminish intracellular levels of ROS, thereby attenuating cellular senescence. In addition, DDO1002 has been demonstrated to ameliorate DNA damage and avert HSC apoptosis, underscoring its potential to mitigate hematopoietic injury precipitated by TBI. Competitive transplantation assay revealed that the administration of DDO1002 can improve the reconstitution and self-renewal capacity of HSCs in aged mice. Single-cell sequencing analysis elucidated that DDO1002 treatment attenuated intracellular inflammatory signaling pathways and mitigated ROS pathway in aged HSCs, suggesting its potential to restore the viability of these cells. Consequently, DDO1002 effectively activated the NRF2-ARE pathway, delaying cellular senescence and ameliorating impaired hematopoiesis, thereby demonstrating its potential as a therapeutic agent for age-related hematopoietic disorders.

Dynamic regulation of the oxidative stress response by the E3 ligase TRIP12

The oxidative stress response is centered on the transcription factor NRF2 and protects cells from reactive oxygen species (ROS). While ROS inhibit the E3 ligase CUL3 KEAP1 to stabilize NRF2 and elicit antioxidant gene expression, cells recovering from stress must rapidly reactivate CUL3 KEAP1 to prevent reductive stress and oxeiptosis-dependent cell death. How cells restore efficient NRF2-degradation upon ROS clearance remains poorly understood. Here, we identify TRIP12, an E3 ligase dysregulated in Clark-Baraitser Syndrome and Parkinson's Disease, as a component of the oxidative stress response. TRIP12 is a ubiquitin chain elongation factor that cooperates with CUL3 KEAP1 to ensure robust NRF2 degradation. In this manner, TRIP12 accelerates stress response silencing as ROS are being cleared, but limits NRF2 activation during stress. The need for dynamic control of NRF2-degradation therefore comes at the cost of diminished stress signaling, suggesting that TRIP12 inhibition could be used to treat degenerative pathologies characterized by ROS accumulation.

Vitamin D as a modulator of molecular pathways involved in CVDs: Evidence from preclinical studies

Vitamin D deficiency (VDD) is a widespread global health issue, affecting nearly a billion individuals worldwide, and mounting evidence links it to an increased risk of cardiovascular diseases like hypertension, atherosclerosis, and heart failure. The discovery of vitamin D receptors and metabolizing enzymes in cardiac and vascular cells, coupled with experimental studies, underscores the complex relationship between vitamin D and cardiovascular health. This review aims to synthesize and critically evaluate the preclinical evidence elucidating the role of vitamin D in cardiovascular health. We examined diverse preclinical in vitro (cardiomyocyte cell line) models and in vivo models, including knockout mice, diet-induced deficiency, and disease-specific animal models (hypertension, hypertrophy and myocardial infarction). These studies reveal that vitamin D modulates vascular tone, and prevents fibrosis and hypertrophy through effects on major signal transduction pathways (NF-kB, Nrf2, PI3K/AKT/mTOR, Calcineurin/NFAT, TGF-β/Smad, AMPK) and influences epigenetic mechanisms governing inflammation, oxidative stress, and pathological remodeling. In vitro studies elucidate vitamin D's capacity to promote cardiomyocyte differentiation and inhibit pathological remodeling. In vivo studies further uncovered detrimental cardiac effects of VDD, while supplementation with vitamin D in cardiovascular disease (CVD) models demonstrated its protective effects by decreasing inflammation, attenuating hypertrophy, reduction in plaque formation, and improving cardiac function. Hence, this comprehensive review emphasizes the critical role of vitamin D in cardiovascular health and its potential as a preventive/therapeutic strategy in CVDs. However, further research is needed to translate these findings into clinical applications as there are discrepancies between preclinical and clinical studies.

NRF2 in age-related musculoskeletal diseases: Role and treatment prospects

The NRF2 pathway is a metabolic- and redox-sensitive signaling axis in which the transcription factor controls the expression of a multitude of genes that enable cells to survive environmental stressors, such as oxidative stress, mainly by inducing the expression of cytoprotective genes. Basal NRF2 levels are maintained under normal physiological conditions, but when exposed to oxidative stress, cells activate the NRF2 pathway, which is crucial for supporting cell survival. Recently, the NRF2 pathway has been found to have novel functions in metabolic regulation and interplay with other signaling pathways, offering novel insights into the treatment of various diseases. Numerous studies have shown that targeting its pathway can effectively investigate the development and progression of age-related musculoskeletal diseases, such as sarcopenia, osteoporosis, osteoarthritis, and intervertebral disc degeneration. Appropriate regulation of the NRF2 pathway flux holds promise as a means to improve musculoskeletal function, thereby providing a new avenue for drug treatment of age-related musculoskeletal diseases in clinical settings. The review summarized an overview of the relationship between NRF2 and cellular processes such as oxidative stress, apoptosis, inflammation, mitochondrial dysfunction, ferroptosis, and autophagy, and explores the potential of targeted NRF2 regulation in the treatment of age-related musculoskeletal diseases.

Sensor systems of KEAP1 uniquely detecting oxidative and electrophilic stresses separately In vivo

In the KEAP1-NRF2 stress response system, KEAP1 acts as a sensor for oxidative and electrophilic stresses through formation of S-S bond and C-S bond, respectively. Of the many questions left related to the sensor activity, following three appear important; whether these KEAP1 sensor systems are operating in vivo, whether oxidative and electrophilic stresses are sensed by the similar or distinct systems, and how KEAP1 equips highly sensitive mechanisms detecting oxidative and electrophilic stresses in vivo. To address these questions, we conducted a series of analyses utilizing KEAP1-cysteine substitution mutant mice, conditional selenocysteine-tRNA (Trsp) knockout mice, and human cohort whole genome sequence (WGS) data. Firstly, the Trsp-knockout provokes severe deficiency of selenoproteins and compensatory activation of NRF2. However, mice lacking homozygously a pair of critical oxidative stress sensor cysteine residues of KEAP1 fail to activate NRF2 in the Trsp-knockout livers. Secondly, this study provides evidence for the differential utilization of KEAP1 sensors for oxidative and electrophilic stresses in vivo. Thirdly, theoretical calculations show that the KEAP1 dimer equips quite sensitive sensor machinery in which modification of a single molecule of KEAP1 within the dimer is sufficient to affect the activity. WGS examinations of rare variants identified seven non-synonymous variants in the oxidative stress sensors in human KEAP1, while no variant was found in electrophilic sensor cysteine residues, supporting the fail-safe nature of the KEAP1 oxidative stress sensor activity. These results provide valuable information for our understanding how mammals respond to oxidative and electrophilic stresses efficiently.

Minimizing Oxidative Stress in the Lens: Alternative Measures for Elevating Glutathione in the Lens to Protect against Cataract

Oxidative stress plays a major role in the formation of the cataract that is the result of advancing age, diabetes or which follows vitrectomy surgery. Glutathione (GSH) is the principal antioxidant in the lens, and so supplementation with GSH would seem like an intuitive strategy to counteract oxidative stress there. However, the delivery of glutathione to the lens is fraught with difficulties, including the limited bioavailability of GSH caused by its rapid degradation, anatomical barriers of the anterior eye that result in insufficient delivery of GSH to the lens, and intracellular barriers within the lens that limit delivery of GSH to its different regions. Hence, more attention should be focused on alternative methods by which to enhance GSH levels in the lens. In this review, we focus on the following three strategies, which utilize the natural molecular machinery of the lens to enhance GSH and/or antioxidant potential in its different regions: the NRF2 pathway, which regulates the transcription of genes involved in GSH homeostasis; the use of lipid permeable cysteine-based analogues to increase the availability of cysteine for GSH synthesis; and the upregulation of the lens's internal microcirculation system, which is a circulating current of Na+ ions that drives water transport in the lens and with it the potential delivery of cysteine or GSH. The first two strategies have the potential to restore GSH levels in the epithelium and cortex, while the ability to harness the lens's internal microcirculation system offers the exciting potential to deliver and elevate antioxidant levels in its nucleus. This is an important distinction, as the damage phenotypes for age-related (nuclear) and diabetic (cortical) cataract indicate that antioxidant delivery must be targeted to different regions of the lens in order to alleviate oxidative stress. Given our increasing aging and diabetic populations it has become increasingly important to consider how the natural machinery of the lens can be utilized to restore GSH levels in its different regions and to afford protection from cataract.

p-Hydroxy benzaldehyde, a phenolic compound from Nostoc commune, ameliorates DSS-induced colitis against oxidative stress via the Nrf2/HO-1/NQO-1/NF-κB/AP-1 pathway

BACKGROUND

Ulcerative colitis (UC), a chronic idiopathic inflammatory bowel disease (IBD), presents with limited current drug treatment options. Consequently, the search for safe and effective drug for UC prevention and treatment is imperative. Our prior studies have demonstrated that the phenolic compound p-Hydroxybenzaldehyde (HD) from Nostoc commune, effectively mitigates intestinal inflammation. However, the mechanisms underlying HD's anti-inflammatory effects remain unclear.

PURPOSE

This study delved into the pharmacodynamics of HD and its underlying anti-inflammation mechanisms.

METHODS

For in vivo experiments, dextran sodium sulfate (DSS)-induced colitis mouse model was established. In vitro inflammation model was established using lipopolysaccharide (LPS)-induced RAW264.7 and bone marrow-derived macrophages (BMDMs). The protective effect of HD against colitis was determined by monitoring clinical symptoms and histological morphology in mice. The levels of inflammatory factors and oxidative stress markers were subsequently analyzed with enzyme-linked immunosorbent assay (ELISA) and biochemical kits. Furthermore, western blotting (WB), immunofluorescence (IF), luciferase reporter gene, drug affinity reaction target stability (DARTS) assay, molecular docking, and molecular dynamics (MD) simulation were used to determine the potential target and molecular mechanism of HD.

RESULTS

Our findings indicate that HD significantly alleviated the clinical symptoms and histological morphology of colitis in mice, and curtailed the production of pro-inflammatory cytokines, including TNF-α, IL-6, IFN-γ, COX-2, and iNOS. Furthermore, HD stimulated the production of SOD, CAT, and GSH-px, enhanced total antioxidant capacity (T-AOC), and reduced MDA levels. Mechanically, HD augmented the expression of Nrf2, HO-1, and NQO-1, while concurrently downregulating the phosphorylation of p65, IκBα, c-Jun, and c-Fos. ML385 and siNrf2 largely attenuated the protective effect of HD in enteritis mice and RAW 264.7 cells, as well as the promotion of HO-1 expression levels. ZnPP-mediated HO-1 knockdown reversed HD-induced inhibition of colonic inflammation. Luciferase reporter assay and IF assay confirmed the transcriptional activation of Nrf2 by HD. DARTS analysis, molecular docking, and MD results showed high binding strength, interaction efficiency and remarkable stability between Nrf2 and HD.

CONCLUSION

These outcomes extend our previous research results that HD can combat oxidative stress through the Nrf2/HO-1/NQO-1/NF-κB/AP-1 pathways, effectively alleviating colitis, and propose new targets for HD to protect against intestinal barrier damage.

REDD1 Is a Promising Therapeutic Target to Combat the Development of Diabetes Complications: A Report on Research Supported by Pathway to Stop Diabetes

The stress response protein regulated in development and DNA damage response 1 (REDD1) has emerged as a key player in the pathogenesis of diabetes. Diabetes upregulates REDD1 in a variety of insulin-sensitive tissues, where the protein acts to inhibit signal transduction downstream of the insulin receptor. REDD1 functions as a cytosolic redox sensor that suppresses Akt/mTORC1 signaling to reduce energy expenditure in response to cellular stress. Whereas a transient increase in REDD1 contributes to an adaptive cellular response, chronically elevated REDD1 levels are implicated in disease progression. Recent studies highlight the remarkable benefits of both whole-body and tissue-specific REDD1 deletion in preclinical models of type 1 and type 2 diabetes. In particular, REDD1 is necessary for the development of glucose intolerance and the consequent rise in oxidative stress and inflammation. Here, we review studies that support a role for chronically elevated REDD1 levels in the development of diabetes complications, reflect on limitations of prior therapeutic approaches targeting REDD1 in patients, and discuss potential opportunities for future interventions to improve the lives of people living with diabetes. This article is part of a series of Perspectives that report on research funded by the American Diabetes Association Pathway to Stop Diabetes program.

ARTICLE HIGHLIGHTS

The hydrophobicity of the CARD8 N-terminus tunes inflammasome activation

Mounting evidence indicates that proteotoxic stress is a primary activator of the CARD8 inflammasome, but the complete array of signals that control this inflammasome have not yet been established. Notably, we recently discovered that several hydrophobic radical-trapping antioxidants (RTAs), including JSH-23, potentiate CARD8 inflammasome activation through an unknown mechanism. Here, we report that these RTAs directly alkylate several cysteine residues in the N-terminal disordered region of CARD8. These hydrophobic modifications destabilize the repressive CARD8 N-terminal fragment and accelerate its proteasome-mediated degradation, thereby releasing the inflammatory CARD8 C-terminal fragment from autoinhibition. Consistently, we also found that unrelated (non-RTA) hydrophobic electrophiles as well as genetic mutation of the CARD8 cysteine residues to isoleucines similarly potentiate inflammasome activation. Overall, our results not only provide further evidence that protein folding stress is a key CARD8 inflammasome-activating signal, but also indicate that the N-terminal cysteines can play key roles in tuning the response to this stress.

Natural Compounds That Activate the KEAP1/Nrf2 Signaling Pathway as Potential New Drugs in the Treatment of Idiopathic Parkinson's Disease

Recently, a single-neuron degeneration model has been proposed to understand the development of idiopathic Parkinson's disease based on (i) the extremely slow development of the degenerative process before the onset of motor symptoms and during the progression of the disease and (ii) the fact that it is triggered by an endogenous neurotoxin that does not have an expansive character, limiting its neurotoxic effect to single neuromelanin-containing dopaminergic neurons. It has been proposed that aminochrome is the endogenous neurotoxin that triggers the neurodegenerative process in idiopathic Parkinson's disease by triggering mitochondrial dysfunction, oxidative stress, neuroinflammation, dysfunction of both lysosomal and proteasomal protein degradation, endoplasmic reticulum stress and formation of neurotoxic alpha-synuclein oligomers. Aminochrome is an endogenous neurotoxin that is rapidly reduced by flavoenzymes and/or forms adducts with proteins, which implies that it is impossible for it to have a propagative neurotoxic effect on neighboring neurons. Interestingly, the enzymes DT-diaphorase and glutathione transferase M2-2 prevent the neurotoxic effects of aminochrome. Natural compounds present in fruits, vegetables and other plant products have been shown to activate the KEAP1/Nrf2 signaling pathway by increasing the expression of antioxidant enzymes including DT-diaphorase and glutathione transferase. This review analyzes the possibility of searching for natural compounds that increase the expression of DT-diaphorase and glutathione transferase through activation of the KEAP1/Nrf2 signaling pathway.

Lactobacilli Cell-Free Supernatants Modulate Inflammation and Oxidative Stress in Human Microglia via NRF2-SOD1 Signaling

Microglia are macrophage cells residing in the brain, where they exert a key role in neuronal protection. Through the gut-brain axis, metabolites produced by gut commensal microbes can influence brain functions, including microglial activity. The nuclear factor erythroid 2-related factor 2 (NRF2) is a key regulator of the oxidative stress response in microglia, controlling the expression of cytoprotective genes. Lactobacilli-derived cell-free supernatants (CFSs) are postbiotics that have shown antioxidant and immunomodulatory effects in several in vitro and in vivo studies. This study aimed to explore the effects of lactobacilli CFSs on modulating microglial responses against oxidative stress and inflammation. HMC3 microglia were exposed to lipopolysaccaride (LPS), as an inflammatory trigger, before and after administration of CFSs from three human gut probiotic species. The NRF2 nuclear protein activation and the expression of NRF2-controlled antioxidant genes were investigated by immunoassay and quantitative RT-PCR, respectively. Furthermore, the level of pro- and anti-inflammatory cytokines was evaluated by immunoassay. All CFSs induced a significant increase of NRF2 nuclear activity in basal conditions and upon inflammation. The transcription of antioxidant genes, namely heme oxygenase 1, superoxide dismutase (SOD), glutathione-S transferase, glutathione peroxidase, and catalase also increased, especially after inflammatory stimulus. Besides, higher SOD1 activity was detected relative to inflamed microglia. In addition, CFSs pre-treatment of microglia attenuated pro-inflammatory TNF-α levels while increasing anti-inflammatory IL-10 levels. These findings confirmed that gut microorganisms' metabolites can play a relevant role in adjuvating the microglia cellular response against neuroinflammation and oxidative stress, which are known to cause neurodegenerative diseases.

Activation of Nuclear Factor Erythroid 2-Related Factor-2 by Oxylipin from Mangifera indica Leaves

Mangifera indica L., a member of the Anacardiaceae family, is widely cultivated across the globe. The leaves of M. indica are renowned for their medicinal properties, attributed to the abundance of bioactive compounds. This study investigated the effects of mango leaf extract on oxidative stress in HeLa cells. Notably, the n-hexane fraction (MLHx) significantly enhanced antioxidant response element (ARE)-luciferase activity at a concentration of 100 µg/mL, surpassing other fractions. MLHx also promoted the expression of HO-1 mRNA by increasing nuclear NRF2 levels. The molecular mechanism of MLHx involves increased phosphorylation of ERK1/2 and stabilization of NRF2. Bioactivity-guided isolation resulted in the identification of six oxylipins: 13(R)-hydroxy-octadeca-(9Z,11E,15Z)-trienoic acid (C-1), 9(R)-hydroxy-octadeca-(10E,12Z,15Z)-trienoic acid (C-2), 13(R)-hydroxy-(9Z,11E)-octadecadienoic acid (C-3), 9(R)-hydroxy-(10E,12Z)-octadecadienoic acid (C-4), 9-oxo-(10E,12E)-octadecadienoic acid (C-5), and 9-oxo-(10E,12Z)-octadecadienoic acid (C-6). These structures were elucidated using comprehensive spectroscopic techniques, including MS and 1H NMR. Additionally, compounds C-7 (9-oxo-(10E,12Z,15Z)-octadecatrienoic acid) and 8 (13-oxo-(9E,11E)-octadecadienoic acid) were characterized by LC-MS/MS mass fragmentation. This study reports the isolation of compounds 1-6 from M. indica for the first time. When tested for their effect on NRF2 activity in HeLa cells, compounds 3, 5, and 6 showed strong stimulation of ARE-luciferase activity in a dose-dependent manner.

Protein degrons and degradation: Exploring substrate recognition and pathway selection in plants

Proteome composition is dynamic and influenced by many internal and external cues, including developmental signals, light availability, or environmental stresses. Protein degradation, in synergy with protein biosynthesis, allows cells to respond to various stimuli and adapt by reshaping the proteome. Protein degradation mediates the final and irreversible disassembly of proteins, which is important for protein quality control and to eliminate misfolded or damaged proteins, as well as entire organelles. Consequently, it contributes to cell resilience by buffering against protein or organellar damage caused by stresses. Moreover, protein degradation plays important roles in cell signaling, as well as transcriptional and translational events. The intricate task of recognizing specific proteins for degradation is achieved by specialized systems that are tailored to the substrate's physicochemical properties and subcellular localization. These systems recognize diverse substrate cues collectively referred to as "degrons," which can assume a range of configurations. They are molecular surfaces recognized by E3 ligases of the ubiquitin-proteasome system but can also be considered as general features recognized by other degradation systems, including autophagy or even organellar proteases. Here we provide an overview of the newest developments in the field, delving into the intricate processes of protein recognition and elucidating the pathways through which they are recruited for degradation.

Carbon monoxide-releasing molecule-3 exerts neuroprotection effects after cardiac arrest in mice: A randomized controlled study

Background

Post-cardiac arrest brain injury (PCABI) is the leading cause of death in survivors of cardiac arrest (CA). Carbon monoxide-releasing molecule (CORM-3) is a water-soluble exogenous carbon monoxide that has been shown to have neuroprotection benefits in several neurological disease models. However, the effects of CORM-3 on PCABI is still unclear.

Methods

A mice model combined asystole with hemorrhage was used. Mice were anesthetized and randomized into 4 groups (n = 12/group) and underwent either 9.5 min CA followed by cardiopulmonary resuscitation (CPR) or sham surgery. CORM-3 (30 mg/kg) or vehicle (normal saline) were administered at 1 h after return of spontaneous circulation or sham surgery. Survival, neurologic deficits, alterations in the permeability of the brain-blood barrier and cerebral blood flow, changes of oxidative stress level, level of neuroinflammation and neuronal degeneration, and the activation of Nrf2/HO-1 signaling pathway were measured.

Results

In CORM-3 treated mice that underwent CA/CPR, significantly improved survival (75.00% vs. 58.33%, P = 0.0146 (24 h) and 66.67% vs. 16.67%, P < 0.0001 (72 h)) and neurological function were observed at 24 h and 72 h after ROSC (P < 0.05 for each). Additionally, increased cerebral blood flow, expression of tight junctions, and reduced reactive oxygen species generation at 24 h after ROSC were observed (P < 0.05 for each). CORM-3 treated mice had less neuron death and alleviated neuroinflammation at 72 h after ROSC (P < 0.05 for each). Notably, the Nrf2/HO-1 signaling pathway was significantly activated in mice subjected to CA/CPR with CORM-3 treatment.

Conclusions

CORM-3 could improve survival and exert neuroprotection after CA/CPR in mice. CORM-3 may be a novel and promising pharmacological therapy for PCABI.

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.