Non-canonical Keap1-independent activation of Nrf2 in astrocytes by mild oxidative stress

Coix Seed Oil Alleviates Hyperuricemia in Mice by Ameliorating Oxidative Stress and Intestinal Microbial Composition

Background: Coix seed oil (YRO), rich in unsaturated fatty acids, has emerged as a promising intervention for hyperuricemia (HUA) due to its potential to alleviate oxidative damage and support organ health. Methods: The fatty acid composition of YRO was determined by gas chromatography-mass spectrometry (GC-MS). A HUA mouse model was established, and serum markers and hepatic enzymes were evaluated. Renal mitochondrial function was assessed using immunohistochemistry and immunofluorescence, and urate transporter expression, along with key signaling proteins, was quantified by Western blot analysis. Additionally, gut microbiota composition was analyzed, and non-targeted metabolomics was performed to observe alterations in serum lipid metabolites. Results: YRO significantly reduced serum uric acid (UA) levels and normalized hepatic enzyme activities. Histological evaluation revealed less tissue damage in both the kidney and the intestine. In the kidney, YRO improved mitochondrial function and supported antioxidant defenses via regulation of Keap1/Nrf2 signaling. In the intestine, YRO enhanced barrier integrity by increasing ZO-1, Occludin, and Claudin-1 expression. Moreover, YRO modulated gut microbiota by increasing beneficial bacteria (Muribaculaceae, Prevotellaceae UCG-001, Lachnospiraceae_ NK4A136_group, Akkermansia) while suppressing harmful species (Bacteroides, Dubosiella). Lipid metabolomics indicated a restoration of phospholipid balance through modulation of the PI3K/AKT/mTOR pathway. Conclusions: YRO supported metabolic health by promoting UA homeostasis, enhancing mitochondrial function, reinforcing antioxidant capacity, and maintaining gut integrity. These findings suggest that coix seed oil could serve as a nutritional supplement in managing HUA and related metabolic disturbances.

Effect and mechanism of Dichloroacetate in the treatment of stroke and the resolution strategy for side effect

Stroke is a serious disease that leads to high morbidity and mortality, and ischemic stroke accounts for more than 80% of strokes. At present, the only effective drug recombinant tissue plasminogen activator is limited by its indications, and its clinical application rate is not high. Therefore, it is urgent to develop effective new drugs according to the pathological mechanism. In the hypoxic state after ischemic stroke, anaerobic glycolysis has become the main way to provide energy to the brain. This process is essential for the maintenance of important brain functions and has important implications for recovery after stroke. However, acidosis caused by anaerobic glycolysis and lactic acid accumulation is an important pathological process after ischemic stroke. Dichloroacetate (DCA) is an orphan drug that has been used for decades to treat children with genetic mitochondrial diseases. Some studies have confirmed the role of DCA in stroke, but the conclusions are conflicting because some believe that DCA is not effective for ischemic stroke and may aggravate hemorrhagic stroke. This study reviews these studies and finds that DCA has a good effect on ischemic stroke. DCA can protect ischemic stroke by improving oxidative stress, reducing neuroinflammation, inhibiting apoptosis, protecting blood-brain barrier, and regulating metabolism. We also describe the differences in the outcomes of DCA in the treatment of ischemic stroke and the reasons why DCA aggravate hemorrhagic stroke. In addition, DCA, as a water disinfection byproduct, has been concerned about its toxicity. We describe the causes and solutions of peripheral neuropathy caused by DCA. In summary, this study analyzes the neuroprotective mechanism of DCA in ischemic stroke and the contradiction of the different research results, and discusses the causes and solutions of its adverse effects.

A CRISPR-edited isoform of the AMPK kinase LKB1 improves the response to cisplatin in A549 lung cancer cells

Lung cancer presents the highest mortality rate in the world when compared to other cancer types and often presents chemotherapy resistance to cisplatin. The A549 nonsmall cell lung cancer line is widely used as a model for lung adenocarcinoma studies since it presents a high proliferative rate and a nonsense mutation in the STK11 gene. The LKB1 protein, encoded by the STK11 gene, is one of the major regulators of cellular metabolism through AMPK activation under nutrient deprivation. Mutation in the STK11 gene in A549 cells potentiates cancer hallmarks, such as deregulation of cellular metabolism, aside from the Warburg effect, mTOR activation, autophagy inhibition, and NRF2 and redox activation. In this study, we investigated the integration of these pathways associated with the metabolism regulation by LKB1/AMPK to improve cisplatin response in the A549 cell line. We first used the CRISPR/Cas9 system to generate cell lines with a CRISPR-edited LKB1 isoform (called Super LKB1), achieved through the introduction of a +1 adenine insertion in the first exon of the STK11 gene after NHEJ-mediated repair. This insertion led to the expression of a higher molecular weight protein containing an alternative exon described in the Peutz-Jeghers Syndrome. Through metabolic regulation by Super LKB1 expression and AMPK activation, we found an increase in autophagy flux (LC3 GFP/RFP p < 0.05), as well as a reduction in the phosphorylation of mTORC1 downstream targets (S6K2 phospho-serine 423; p < 0.05; and S6 ribosomal protein phospho-serine 240/244; p < 0.03). The NRF2 protein exhibited increased levels and more nuclear localization in A549 WT cells compared to the edited cells (p < 0.01). We also observed lower levels of H2O2 in the WT A549 cells, as a possible result of NRF2 activation, and a higher requirement of cisplatin to achieve the IC50 (WT: 10 μM; c2SL+: 5.5 μM; c3SL+: 6 μM). The data presented here suggests that the regulation of molecular pathways by the novel Super LKB1 in A549 cells related to metabolism, mTORC1, and autophagy promotes a better response of lung cancer cells to cisplatin. This NHEJ-CRISPR-based approach may be potentially used for lung cancer gene therapy.

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.

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.

Exploring the Therapeutic Potential of Cannabidiol in U87MG Cells: Effects on Autophagy and NRF2 Pathway

Cannabinoids include both endogenous endocannabinoids and exogenous phytocannabinoids, such as cannabidiol (CBD), and have potential as therapeutic agents in cancer treatment due to their selective anticancer activities. CBD exhibits both antioxidant and pro-oxidant effects depending on its concentration and cell types. These properties allow CBD to influence oxidative stress responses and potentially enhance the efficacy of antitumor therapies. In this study, we treated U87MG glioma cells with low dose (1 μM) CBD and evaluated its molecular effects. Our findings indicate that CBD reduced cell viability by 20% (p < 0.05) through the alteration of mitochondrial membrane potential. The alteration of redox status by CBD caused an attempt to rescue mitochondrial functionality through nuclear localization of the GABP transcription factor involved in mitochondria biogenesis. Moreover, CBD treatment caused an increase in autophagic flux, as supported by the increase in Beclin-1 and the ratio of LC3-II/LC3-I. Due to mitochondria functionality alteration, pro-apoptotic proteins were induced without activating apoptotic effectors Caspase-3 or Caspase-7. The study of the transcription factor NRF2 and the ubiquitin-binding protein p62 expression revealed an increase in their levels in CBD-treated cells. In conclusion, low-dose CBD makes U87MG cells more vulnerable to cytotoxic effects, reducing cell viability and mitochondrial dynamics while increasing autophagic flux and redox systems. This explains the mechanisms by which glioma cells respond to CBD treatment. These findings highlight the therapeutic potential of CBD, suggesting that modulating NRF2 and autophagy pathways could represent a promising strategy for glioblastoma treatment.

Unveiling Smyd-2's Role in Cytoplasmic Nrf-2 Sequestration and Ferroptosis Induction in Hippocampal Neurons After Cerebral Ischemia/Reperfusion

SET and MYND Domain-Containing 2 (Smyd-2), a specific protein lysine methyltransferase (PKMT), influences both histones and non-histones. Its role in cerebral ischemia/reperfusion (CIR), particularly in ferroptosis-a regulated form of cell death driven by lipid peroxidation-remains poorly understood. This study identifies the expression of Smyd-2 in the brain and investigates its relationship with neuronal programmed cell death (PCD). We specifically investigated how Smyd-2 regulates ferroptosis in CIR through its interaction with the Nuclear Factor Erythroid-2-related Factor-2 (Nrf-2)/Kelch-like ECH-associated protein (Keap-1) pathway. Smyd-2 knockout protects HT-22 cells from Erastin-induced ferroptosis but not TNF-α + Smac-mimetic-induced apoptosis/necroptosis. This neuroprotective effect of Smyd-2 knockout in HT-22 cells after Oxygen-Glucose Deprivation/Reperfusion (OGD/R) was reversed by Erastin. Smyd-2 knockout in HT-22 cells shows neuroprotection primarily via the Nuclear Factor Erythroid-2-related Factor-2 (Nrf-2)/Kelch-like ECH-associated protein (Keap-1) pathway, despite the concurrent upregulation of Smyd-2 and Nrf-2 observed in both the middle cerebral artery occlusion (MCAO) and OGD/R models. Interestingly, vivo experiments demonstrated that Smyd-2 knockout significantly reduced ferroptosis and lipid peroxidation in hippocampal neurons following CIR. Moreover, the Nrf-2 inhibitor ML-385 abolished the neuroprotective effects of Smyd-2 knockout, confirming the pivotal role of Nrf-2 in ferroptosis regulation. Cycloheximide (CHX) fails to reduce Nrf-2 expression in Smyd-2 knockout HT-22 cells. Smyd-2 knockout suppresses Nrf-2 lysine methylation, thereby promoting the Nrf-2/Keap-1 pathway without affecting the PKC-δ/Nrf-2 pathway. Conversely, Smyd-2 overexpression disrupts Nrf-2 nuclear translocation, exacerbating ferroptosis and oxidative stress, highlighting its dual regulatory role. This study underscores Smyd-2's potential for ischemic stroke treatment by disrupting the Smyd-2/Nrf-2-driven antioxidant capacity, leading to hippocampal neuronal ferroptosis. By clarifying the intricate interplay between ferroptosis and oxidative stress via the Nrf-2/Keap-1 pathway, our findings provide new insights into the molecular mechanisms of CIR and identify Smyd-2 as a promising therapeutic target.

The Crosstalk between Autophagy and Nrf2 Signaling in Cancer: from Biology to Clinical Applications

Autophagy is a catabolic process that has been conserved throughout evolution, serving to degrade and recycle cellular components and damaged organelles. Autophagy is activated under various stress conditions, such as nutrient deprivation, viral infections, and genotoxic stress, and operates in conjunction with other stress response pathways to mitigate oxidative damage and maintain cellular homeostasis. One such pathway is the Nrf2-Keap1-ARE signaling axis, which functions as an intrinsic antioxidant defense mechanism and has been implicated in cancer chemoprevention, tumor progression, and drug resistance. Recent research has identified a link between impaired autophagy, mediated by the autophagy receptor protein p62, and the activation of the Nrf2 pathway. Specifically, p62 facilitates Keap1 degradation through selective autophagy, leading to the translocation of Nrf2 into the nucleus, where it transcriptionally activates downstream antioxidant enzyme expression, thus safeguarding cells from oxidative stress. Furthermore, Nrf2 regulates p62 transcription, so a positive feedback loop involving p62, Keap1, and Nrf2 is established, which amplifies the protective effects on cells. This paper aims to provide a comprehensive review of the roles of Nrf2 and autophagy in cancer progression, the regulatory interactions between the Nrf2 pathway and autophagy, and the potential applications of the Nrf2-autophagy signaling axis in cancer therapy.

Spatiotemporally cascade-driven "Lipomicelles" enhance extracellular matrix penetration and remodel intercellular crosstalk in pulmonary fibrosis

Pulmonary fibrosis (PF) is an inevitable phase of many respiratory diseases with high mortality and limited effective treatments in the clinic. In PF, aberrant extracellular matrix (ECM) deposition is a significant pathological structural alteration that blocks intercellular crosstalk and hinders the deep penetration of therapeutics into lung tissues, reducing the effectiveness of conventional treatment strategies. Herein, a penetrating enhancer (Lipomicelles) composed of thermosensitive liposome shells loaded with collagenase IV and micellar cores containing thioketal bonds encapsulated with curcumin and decorated with cyclic RGDfc, is developed to alleviate PF. Specifically, Lipomicelles exhibit a cascade-responsive pattern to achieve precision delivery of curcumin through thermosensitivity, enhanced ECM penetration, site-specific targeting, and rapid release in injured alveolar epithelial type II cells (CellAEC2s). Subsequently, intercellular crosstalk is remodeled through the curcumin-mediated repair of CellAEC2s, combined with collagenase IV-mediated ECM degradation to inhibit myofibroblasts, ultimately achieving PF reversal. This work provides an innovative approach to enhance ECM penetration of therapeutics before remodeling intercellular crosstalk, addressing multi-phase PF therapy.

Nuclear factor erythroid 2-related factor-mediated signaling alleviates ferroptosis during cerebral ischemia-reperfusion injury

Cardiac arrest (CA) is a significant challenge for emergency physicians worldwide and leads to increased morbidity and mortality rates. The poor prognosis of CA primarily stems from the complexity and irreversibility of cerebral ischemia-reperfusion injury (CIRI). Ferroptosis, a form of programmed cell death characterized by iron overload and lipid peroxidation, plays a crucial role in the progression and treatment of CIRI. In this review, we highlight the mechanisms of ferroptosis within the context of CIRI, focusing on its role as a key contributor to neuronal damage and dysfunction post-CA. We explore the crucial involvement of the nuclear factor erythroid 2-related factor (Nrf2)-mediated signaling pathway in modulating ferroptosis-associated processes during CIRI. Through comprehensive analysis of the regulatory role of Nrf2 in the cellular responses to oxidative stress, we highlight its potential as a therapeutic target for mitigating ferroptotic cell death and improving the neurological prognosis of patients experiencing CA. Furthermore, we discuss interventions targeting the Kelch-like ECH-associated protein 1/Nrf2/antioxidant response element pathway, including the use of traditional Chinese medicine and Western medicine, which demonstrate potential for attenuating ferroptosis and preserving neuronal function in CIRI. Owing to the limitations in the safety, specificity, and effectiveness of Nrf2-targeted drugs, as well as the technical difficulties and ethical constraints in obtaining the results related to the brain pathological examination of patients, most of the studies focusing on Nrf2-related regulation of ferroptosis in CIRI are still in the basic research stage. Overall, this review aims to provide a comprehensive understanding of the mechanisms underlying ferroptosis in CIRI, offering insights into novel therapeutics aimed at enhancing the clinical outcomes of patients with CA.

Glutathione synthesis in the mouse liver supports lipid abundance through NRF2 repression

Cells rely on antioxidants to survive. The most abundant antioxidant is glutathione (GSH). The synthesis of GSH is non-redundantly controlled by the glutamate-cysteine ligase catalytic subunit (GCLC). GSH imbalance is implicated in many diseases, but the requirement for GSH in adult tissues is unclear. To interrogate this, we have developed a series of in vivo models to induce Gclc deletion in adult animals. We find that GSH is essential to lipid abundance in vivo. GSH levels are highest in liver tissue, which is also a hub for lipid production. While the loss of GSH does not cause liver failure, it decreases lipogenic enzyme expression, circulating triglyceride levels, and fat stores. Mechanistically, we find that GSH promotes lipid abundance by repressing NRF2, a transcription factor induced by oxidative stress. These studies identify GSH as a fulcrum in the liver's balance of redox buffering and triglyceride production.

Nrf2 for a key member of redox regulation: A novel insight against myocardial ischemia and reperfusion injuries

Nuclear factor erythroid-2 related factor 2 (Nrf2), a nuclear transcription factor, modulates genes responsible for antioxidant responses against toxic and oxidative stress to maintain redox homeostasis and participates in varieties of cellular processes such as metabolism and inflammation during myocardial ischemia and reperfusion injuries (MIRI). The accumulation of reactive oxygen species (ROS) from damaged mitochondria, xanthine oxidase, NADPH oxidases, and inflammation contributes to depraved myocardial ischemia and reperfusion injuries. Considering that Nrf2 played crucial roles in antagonizing oxidative stress, it is reasonable to delve into the up or down-regulated molecular mechanisms of Nrf2 in the progression of MIRI to provide the possibility of new therapeutic medicine targeting Nrf2 in cardiovascular diseases. This review systematically describes the generation of ROS, the regulatory metabolisms of Nrf2 as well as several natural or synthetic compounds activating Nrf2 during MIRI, which might provide novel insights for the anti-oxidative stress and original ideas targeting Nrf2 for the prevention and treatment in cardiovascular diseases.

Microglia-dependent neuroprotective effects of 4-octyl itaconate against rotenone-and MPP+-induced neurotoxicity in Parkinson's disease

Chronic neuroinflammation is implicated in the pathogenesis of Parkinson's disease (PD), one of the most common neurodegenerative diseases. Itaconate, an endogenous metabolite derived from the tricarboxylic acid cycle via immune-responsive gene 1 activity, may mediate anti-inflammatory responses by activation of the nuclear factor erythroid 2-related factor 2 (Nrf2) antioxidant pathway. This study investigates the neuroprotective potential of 4-octyl itaconate (OI), a cell-permeable derivative of itaconate, in cellular models of PD. OI not only suppressed lipopolysaccharide-induced proinflammatory cascades of inducible nitric oxide synthase, cyclooxygenase-2, and cytokines release in mouse BV2 microglial cells but also activated the Nrf2 signaling pathway and its downstream targets in these cells. Conditioned medium derived from OI-treated BV2 cells protected against rotenone- and MPP+-induced neurotoxicity in Neuro 2A cells. Overall, our findings support the anti-inflammatory neuroprotective potential of OI in PD.

The consequences of neurodegenerative disease on neuron-astrocyte metabolic and redox interactions

Brain metabolic pathways relating to bioenergetic and redox homeostasis are closely linked, and deficits in these pathways are thought to occur in many neurodegenerative diseases. Astrocytes play important roles in both processes, and growing evidence suggests that neuron-astrocyte intercellular signalling ensures brain bioenergetic and redox homeostasis in health. Moreover, alterations to this crosstalk have been observed in the context of neurodegenerative pathology. In this review, we summarise the current understanding of how neuron-astrocyte interactions influence brain metabolism and antioxidant functions in health as well as during neurodegeneration. It is apparent that deleterious and adaptive protective responses alter brain metabolism in disease, and that knowledge of both may illuminate targets for future therapeutic interventions.

The KEAP1-NRF2 System and Neurodegenerative Diseases

Significance: Central nervous system (CNS) diseases are disorders of the brain and/or spinal cord and include neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and multiple sclerosis. Nuclear factor erythroid 2-related factor 2 (NRF2) is a transcription factor belonging to the cap-n-collar family that harbors a unique basic leucine zipper motif and plays as a master regulator of homeostatic responses. Recent Advances: Kelch-like ECH-associated protein 1 (KEAP1) is an adaptor of the Cullin3 (CUL3)-based ubiquitin E3 ligase that enhances the ubiquitylation of NRF2, which promotes the degradation of NRF2 to suppress its transcriptional activity in the absence of stress. Cysteine residues of KEAP1 are modified under stress conditions, and NRF2 degradation is attenuated, allowing it to accumulate and induce the expression of target genes. This regulatory system is referred to as the KEAP1-NRF2 system and plays a central role in protecting cells against various stresses. NRF2 also negatively regulates the expression of inflammatory cytokine and chemokine genes and suppresses pathological inflammation. As oxidative stress, inflammation, and proteostasis are known to contribute to neurodegenerative diseases, the KEAP1-NRF2 system is an attractive target for the treatment of these diseases. Critical Issues: In mouse models of neurodegenerative diseases, Nrf2 depletion exacerbates symptoms and enhances oxidative damage and inflammation in the CNS. In contrast, chemical or genetic NRF2 activation improves these symptoms. Indeed, the NRF2-activating chemical dimethyl fumarate is now widely used for the clinical treatment of MS. Future Directions: The KEAP1-NRF2 system is a promising therapeutic target for neurodegenerative diseases.

Social isolation after chronic unpredictable mild stress perpetuates depressive-like behaviors, memory deficits and social withdrawal via inhibiting ERK/KEAP1/NRF2 signaling

BACKGROUND

Social withdrawal in patients with depression can aggravate depressive symptoms. However, few studies focus on the behavioral changes of social isolation after CUMS. NRF2 had been reported to be down-regulated after CUMS. But whether NRF2 participates in behavioral changes induced by social isolation after CUMS remains unclear. This study aims to develop a new model combined social isolation with CUMS, and investigate whether such behavioral changes are related to NRF2 signaling.

METHODS

This study included two stages. In Stage 1, rats were subjected to 4-week CUMS and CUMS-susceptible rats were selected. In Stage 2, the CUMS-susceptible rats received 4-week social isolation or social support. Behavioral tests were carried out to observe behavioral changes, including sucrose preference test, forced swimming test, open field test, novel object recognition and social interaction test. QRT-PCR, western blot and immunofluorescence staining detected the ERK/KEAP1/NRF2 signaling.

RESULTS

CUMS-susceptible rats exhibited depressive-like behaviors accompanied by the down-regulated ERK/KEAP1/NRF2 signaling in hippocampus. In Stage 2, compared with 4-week social support (group CUMSG), 4-week social isolation (group CUMSI) perpetuated the depressive-like behaviors, memory deficits and social withdrawal in CUMS-susceptible rats, as well as lower levels of p-ERK, NRF2, p-NRF2, HO-1 and NQO1, and the higher levels of KEAP1 in hippocampus.

CONCLUSION

These findings suggested that social isolation after CUMS perpetuated depressive-like behaviors, memory deficits and social withdrawal via inhibiting ERK/KEAP1/NRF2 signaling. This study provided molecular evidence for the effects of post-stress social isolation on mental health, and the antioxidant stress signaling might be a target to rescue these.

Crosstalk between autophagy and the Keap1-Nrf2-ARE pathway regulates realgar-induced neurotoxicity

ETHNOPHARMACOLOGICAL RELEVANCE

Realgar, the main component of which is As₂S₂ or As₄S₄ (≥90%), is a traditional Chinese natural medicine that has been used to treat carbuncles, furuncles, snake and insect bites, abdominal pain caused by parasitic worms, and epilepsy in China for many years. Because realgar contains arsenic, chronic or excessive use of single-flavor realgar and realgar-containing Chinese patent medicine can lead to drug-induced arsenic poisoning, but the exact mechanism underlying its toxicity to the central nervous system is unclear.

AIM OF THE STUDY

The aim of this study was to clarify the mechanism of realgar-induced neurotoxicity and to investigate the effects of realgar on autophagy and the Keap1-Nrf2-ARE pathway.

MATERIALS AND METHODS

We used rats treated with the autophagy inhibitor 3-methyladenine (3-MA) or adeno-associated virus (AAV2/9-r-shRNA-Sqstm1, sh-p62) to investigate realgar-induced neurotoxicity and explore the specific relationship between autophagy and the Keap1-Nrf2-ARE pathway (the Nrf2 pathway) in the cerebral cortex. Molecular docking analysis was used to assess the interactions among the Nrf2, p62 and Keap1 proteins.

RESULTS

Our results showed that arsenic from realgar accumulated in the brain and blood to cause neuronal and synaptic damage, decrease exploratory behavior and spontaneous movement, and impair memory ability in rats. The mechanism may have involved realgar-mediated autophagy impairment and continuous activation of the Nrf2 pathway via the LC3-p62-Keap1-Nrf2 axis. However, because this activation of the Nrf2 pathway was not sufficient to counteract oxidative damage, apoptosis was aggravated in the cerebral cortex.

CONCLUSIONS

This study revealed that autophagy, the Nrf2 pathway, and apoptosis are involved in realgar-induced central nervous system toxicity and identified p62 as the hub of the LC3-p62-Keap1-Nrf2 axis in the regulation of autophagy, the Nrf2 pathway, and apoptosis.

Piceatannol protects rat neuron cells from oxygen-glucose deprivation reperfusion injury via regulation of GSK-3β/Nrf2 signaling pathway

OBJECTIVE

To investigate the effect and mechanism of piceatannol on cerebral ischemia-reperfusion injury.

METHODS

The oxygen-glucose deprivation reperfusion (OGD/R) model was constructed in primary cultured suckling rat cortical neuron cells. After 2 h of oxygen-glucose deprivation, the cells were treated with piceatannol for 24 h. The cell survival rate was detected by MTT assay, and the degree of cell damage was detected by intracellular lactate dehydrogenase (LDH) release assay. The activity of superoxide dismutase (SOD) and the content of adenosine triphosphate (ATP) were detected by colorimetric method. The content of reactive oxygen species (ROS) was detected by flow cytometry or observed with inverted fluorescence microscope. The ultrastructure of mitochondria was observed with transmission electron microscopy. Western blotting was used to detect the phosphorylation levels of protein kinase B (AKT) and glycogen synthase kinase (GSK)-3β. Immunofluorescence staining was used to observe the nuclear localization of nuclear factor-erythroid 2-related factor (Nrf) 2. After OGD/R neuron cells were pretreated with Nrf2 inhibitor ML385 for 24 h, the effect of Nrf2 on the improvement of cell activity and antioxidant activity of piceatannol were investigated. Western blotting was used to detect the protein expression levels of Nrf2, heme oxygenase (HO) 1 and NADPH quinone oxidoreductase (NQO) 1.

RESULTS

Piceatannol significantly increased the survival rate of OGD/R neurons, decreased LDH release and reactive oxygen species content, increased SOD activity, ameliorated mitochondrial ultrastructural damage, increased mitochondrial membrane potential and ATP level (all P<0.05), increased phosphorylation of AKT and GSK-3β protein, up-regulated the expression of Nrf2, HO-1 and NQO1 protein, increased the nuclear-to-plasma ratio of Nrf2, and promoted the nuclear transfer of Nrf2 (all P<0.05). ML385 could significantly reverse the rescue effect of paclitaxel on the model cells and the regulatory activities of SOD, ROS and LDH (all P<0.05).

CONCLUSION

Piceatannol can regulate Nrf2 by activating GSK-3β signaling pathway, promote its nuclear translocation, exert corresponding antioxidant effect, and protect mitochondrial structure and function in rat neuron cells.

The molecular activity of cannabidiol in the regulation of Nrf2 system interacting with NF-κB pathway under oxidative stress

Cannabidiol (CBD), the major non-psychoactive phytocannabinoid of Cannabis sativa L., is one of the most studied compounds in pharmacotherapeutic approaches to treat oxidative stress-related diseases such as cardiovascular, metabolic, neurodegenerative, and neoplastic diseases. The literature data to date indicate the possibility of both antioxidant and pro-oxidative effects of CBD. Thus, the mechanism of action of this natural compound in the regulation of nuclear factor 2 associated with erythroid 2 (Nrf2), which plays the role of the main cytoprotective regulator of redox balance and inflammation under oxidative stress conditions, seems to be particularly important. Moreover, Nrf2 is strongly correlated with the cellular neoplastic profile and malignancy, which in turn is critical in determining the cellular response induced by CBD under pathophysiological conditions. This paper summarizes the CBD-mediated pathways of regulation of the Nrf2 system by altering the expression and modification of both proteins directly involved in Nrf2 transcriptional activity and proteins involved in the relationship between Nrf2 and the nuclear factor kappa B (NF-κB) which is another redox-sensitive transcription factor.

Adaptive Responses to Hypoxia and/or Hyperoxia in Humans

Significance: Oxygen is indispensable for aerobic life, but its utilization exposes cells and tissues to oxidative stress; thus, tight regulation of cellular, tissue, and systemic oxygen concentrations is crucial. Here, we review the current understanding of how the human organism (mal-)adapts to low (hypoxia) and high (hyperoxia) oxygen levels and how these adaptations may be harnessed as therapeutic or performance enhancing strategies at the systemic level. Recent Advances: Hyperbaric oxygen therapy is already a cornerstone of modern medicine, and the application of mild hypoxia, that is, hypoxia conditioning (HC), to strengthen the resilience of organs or the whole body to severe hypoxic insults is an important preparation for high-altitude sojourns or to protect the cardiovascular system from hypoxic/ischemic damage. Many other applications of adaptations to hypo- and/or hyperoxia are only just emerging. HC-sometimes in combination with hyperoxic interventions-is gaining traction for the treatment of chronic diseases, including numerous neurological disorders, and for performance enhancement. Critical Issues: The dose- and intensity-dependent effects of varying oxygen concentrations render hypoxia- and/or hyperoxia-based interventions potentially highly beneficial, yet hazardous, although the risks versus benefits are as yet ill-defined. Future Directions: The field of low and high oxygen conditioning is expanding rapidly, and novel applications are increasingly recognized, for example, the modulation of aging processes, mood disorders, or metabolic diseases. To advance hypoxia/hyperoxia conditioning to clinical applications, more research on the effects of the intensity, duration, and frequency of altered oxygen concentrations, as well as on individual vulnerabilities to such interventions, is paramount. Antioxid. Redox Signal. 37, 887-912.

Alleviating Effects of Black Soybean Peptide on Oxidative Stress Injury Induced by Lead in PC12 Cells via Keap1/Nrf2/TXNIP Signaling Pathway

Many researchers have found that Pb exposure can cause oxidative stress damage to the body’s tissue. Black soybean peptide (BSP) has a variety of physiological functions, especially in terms of oxidative stress. Nevertheless, the mitigation function of BSPs on Pb-induced oxidative stress damage in PC12 cells has not been clearly defined. In this study, cell viability was detected by CCK8. Oxidative stress indicators, such as ROS, GSH/GSSG, MDA, SOD, CAT, GPx, and GR, were tested with biochemical kit. Protein expression of Keap1, Nrf2, and TXNIP was measured by Western blot. Compared with the control group, Pb reduced the cell viability of PC12 cells. However, BSP treatment significantly increased the viability of PC12 cells induced by lead exposure (p < 0.05). Lead can enrich the contents of MDA and ROS, but decrease the amount of CAT, SOD, GR, GPx, and GSH/GSSG in PC12 cells, while BSP can alleviate it (p < 0.05). Lead can enhance the expression of Keap1 and TXNIP proteins, but reduce Nrf2 expression. In contrast, BSPs reversed this phenomenon (p < 0.05). BSPs can alleviate oxidative stress injury induced by lead in PC12 cells through the Keap1/Nrf2/TXNIP signaling pathway.

Targeting Molecular Mediators of Ferroptosis and Oxidative Stress for Neurological Disorders

With the acceleration of population aging, nervous system diseases including Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), anxiety, depression, stroke, and traumatic brain injury (TBI) have become a huge burden on families and society. The mechanism of neurological disorders is complex, which also lacks effective treatment, so relevant research is required to solve these problems urgently. Given that oxidative stress-induced lipid peroxidation eventually leads to ferroptosis, both oxidative stress and ferroptosis are important mechanisms causing neurological disorders, targeting mediators of oxidative stress and ferroptosis have become a hot research direction at present. Our review provides a current view of the mechanisms underlying ferroptosis and oxidative stress participate in neurological disorders, the potential application of molecular mediators targeting ferroptosis and oxidative stress in neurological disorders. The target of molecular mediators or agents of oxidative stress and ferroptosis associated with neurological disorders, such as reactive oxygen species (ROS), nuclear factor erythroid 2–related factor-antioxidant response element (Nrf2-ARE), n-acetylcysteine (NAC), Fe²⁺, NADPH, and its oxidases NOX, has been described in this article. Given that oxidative stress-induced ferroptosis plays a pivotal role in neurological disorders, further research on the mechanisms of ferroptosis caused by oxidative stress will help provide new targets for the treatment of neurological disorders.

Harnessing redox signaling to overcome therapeutic-resistant cancer dormancy

Dormancy occurs when cells preserve viability but stop proliferating, which is considered an important cause of tumor relapse, which may occur many years after clinical remission. Since the life cycle of dormant cancer cells is affected by both intracellular and extracellular factors, gene mutation or epigenetic regulation of tumor cells may not fully explain the mechanisms involved. Recent studies have indicated that redox signaling regulates the formation, maintenance, and reactivation of dormant cancer cells by modulating intracellular signaling pathways and the extracellular environment, which provides a molecular explanation for the life cycle of dormant tumor cells. Indeed, redox signaling regulates the onset of dormancy by balancing the intrinsic pathways, the extrinsic environment, and the response to therapy. In addition, redox signaling sustains dormancy by managing stress homeostasis, maintaining stemness and immunogenic equilibrium. However, studies on dormancy reactivation are still limited, partly explained by redox-mediated activation of lipid metabolism and the transition from the tumor microenvironment to inflammation. Encouragingly, several drug combination strategies based on redox biology are currently under clinical evaluation. Continuing to gain an in-depth understanding of redox regulation and develop specific methods targeting redox modification holds the promise to accelerate the development of strategies to treat dormant tumors and benefit cancer patients.

Roles of NRF2 in Fibrotic Diseases: From Mechanisms to Therapeutic Approaches

Fibrosis is a persistent inflammatory response that causes scarring and tissue sclerosis by stimulating myofibroblasts to create significant quantities of extracellular matrix protein deposits in the tissue. Oxidative stress has also been linked to the development of fibrosis in several studies. The nuclear erythroid 2-related factor 2 (NRF2) transcription factor controls the expression of several detoxification and antioxidant genes. By binding to antioxidant response elements, NRF2 is activated by oxidative or electrophilic stress and promotes its target genes, resulting in a protective effect on cells. NRF2 is essential for cell survival under oxidative stress conditions. This review describes Kelch-like epichlorohydrin-associated protein 1 (KEAP1)/NRF2 signaling mechanisms and presents recent research advances regarding NRF2 and its involvement in primary fibrotic lesions such as pulmonary fibrosis, hepatic fibrosis, myocardial fibrosis, and renal fibrosis. The related antioxidant substances and drugs are described, along with the mechanisms by which KEAP1/NRF2 regulation positively affects the therapeutic response. Finally, the therapeutic prospects and potential value of NRF2 in fibrosis are summarized. Further studies on NRF2 may provide novel therapeutic approaches for fibrosis.

Hypoxia Induces Oxidative Injury and Apoptosis via Mediating the Nrf-2/Hippo Pathway in Blood Cells of Largemouth Bass (Micropterus salmoides)

Investigating how aquatic animals respond to hypoxia brought about by changes in environmental temperature may be of great significance to avoid oxidative injury and maintain the quality of farmed fish in the background of global warming. Here, we investigated the effects of hypoxia on oxidative injury and environment-sensing pathway in blood cells of Micropterus salmoides. The total blood cell count (TBCC) and Giemsa staining showed that hypoxia could lead to damage of blood cells. Flow cytometry analysis confirmed that the apoptosis rate, Ca2+ level, NO production and ROS of blood cells were significantly increased under hypoxia stress. Environment-sensing pathways, such as Nrf2 pathway showed that hypoxia resulted in significant up-regulation of hiF-1 alpha subunit (Hif-1α), nuclear factor erythroid 2-related factor 2 (Nrf2) and kelch-1ike ECH- associated protein l (Keap1) expression. Meanwhile, the expression of Hippo pathway-related genes such as MOB kinase activator 1 (MOB1), large tumor suppressor homolog 1/2 (Lats1/2), yes-associated protein/transcriptional co-activator with PDZ-binding motif (YAP/TAZ), protein phosphatase 2A (PP2A) were significantly increased in blood cells after hypoxia exposure. In addition, hypoxia stress also increased the expression of catalase (CAT) and glutathione peroxidase (GPx), but decreased the expression of superoxide dismutase (SOD). Consequently, our results suggested that hypoxia could induce oxidative injury and apoptosis via mediating environment-sensing pathway such as Nrf2/Hippo pathway in blood cells of M. salmoides.

Good, bad, and neglectful: Astrocyte changes in neurodegenerative disease

Astrocytes play key roles in CNS development as well as well as neuro-supportive roles in the mature brain including ionic, bioenergetic and redox homeostasis. Astrocytes undergo rapid changes following acute CNS insults such as stroke or traumatic brain injury, but are also profoundly altered in chronic neurodegenerative conditions such as Alzheimer's disease. While disease-altered astrocytes are often referred to as reactive, this does not represent a single cellular state or group of states, but a shift in astrocyte properties that is determined by the type of insult as well as spatio-temporal factors. Such changes can accelerate disease progression due to astrocytes neglecting their normal homeostatic neuro-supportive roles, as well as by gaining active neuro-toxic properties. However, other aspects of astrocytic responses to chronic disease can include the induction of adaptive-protective pathways. This is particularly the case when considering antioxidant defences, which can be up-regulated in many cell types, including astrocytes, in response to stresses, sometimes in concert with the activation of detoxification and proteostasis pathways. Protective responses, whilst potentially serving to mitigate neuronal dysfunction, may ultimately fail due to being insufficiently strong, or be offset by other deleterious changes to astrocytes occurring in parallel. Nevertheless, a greater understanding of early adaptive-protective responses of astrocytes to neurodegenerative disease pathology may point to ways in which these responses may be harnessed for therapeutic effect.

Adaptative Up-Regulation of PRX2 and PRX5 Expression Characterizes Brain from a Mouse Model of Chorea-Acanthocytosis

The peroxiredoxins (PRXs) constitute a ubiquitous antioxidant. Growing evidence in neurodegenerative disorders such as Parkinson’s disease (PD) or Alzheimer’s disease (AD) has highlighted a crucial role for PRXs against neuro-oxidation. Chorea-acanthocytosis/Vps13A disease (ChAc) is a devastating, life-shortening disorder characterized by acanthocytosis, neurodegeneration and abnormal proteostasis. We recently developed a Vps13a^−/− ChAc-mouse model, showing acanthocytosis, neurodegeneration and neuroinflammation which could be restored by LYN inactivation. Here, we show in our Vps13a^−/− mice protein oxidation, NRF2 activation and upregulation of downstream cytoprotective systems NQO1, SRXN1 and TRXR in basal ganglia. This was associated with upregulation of PRX2/5 expression compared to wild-type mice. PRX2 expression was age-dependent in both mouse strains, whereas only Vps13a^−/− PRX5 expression was increased independent of age. LYN deficiency or nilotinib-mediated LYN inhibition improved autophagy in Vps13a^−/− mice. In Vps13a^−/−; Lyn^−/− basal ganglia, absence of LYN resulted in reduced NRF2 activation and down-regulated expression of PRX2/5, SRXN1 and TRXR. Nilotinib treatment of Vps13a^−/− mice reduced basal ganglia oxidation, and plasma PRX5 levels, suggesting plasma PRX5 as a possible ChAc biomarker. Our data support initiation of therapeutic Lyn inhibition as promptly as possible after ChAc diagnosis to minimize development of irreversible neuronal damage during otherwise inevitable ChAc progression.