Nrf2-antioxidant Response Element Research Articles

A Morpholine Derivative N-(4-Morpholinomethylene)ethanesulfonamide Induces Ferroptosis in Tumor Cells by Targeting NRF2.

Small molecule drugs containing morpholine-based moieties have become crucial candidates in the tumor targeted therapy strategies, but the specific molecular mechanisms of these drugs causing tumor cell death require further investigation. The morpholine derivative N-(4-morpholinomethylene)ethanesulfonamide (MESA) was used to stimulate prostate and ovarian cancer cells and we focused on the ferroptosis effects, including the target molecule and signal pathways mediated by MESA. The results showed that MESA could induce ferroptosis to cause the proliferation inhibition and apoptosis effects of tumor cells according to the identification of ferroptosis inhibitor fer-1 and other cell death inhibitors. Further MESA could significantly increase the intracellular malondialdehyde (MDA), reactive oxygen species (ROS) and Fe2+ levels in tumor cells and mediate the dynamic changes of ferroptosis-relative molecules GPX4, nuclear factor erythroid2-related factor 2 (NRF2), ACSL4, SLC7A11 and P62-Kelch-like ECH-associated protein 1 (KEAP1)-NRF2-antioxidant response element (ARE) signal pathways. Further, NRF2 overexpression could reduce the tumor cell death and ROS levels exposure to MESA. Most importantly, it was confirmed that MESA could bind to NRF2 protein through molecular docking and thermal stability assays and NRF2 was a target molecule of MESA for inducing ferroptosis effects in tumor cells. Collectively, our findings indicated the ferroptosis effects of the morpholine derivative MESA in prostate and ovarian cancer cells and its function mechanism including targeted molecule and signal pathways, which would be helpful for developing MESA as a prospective small molecule drug for cancer therapy based on cell ferroptosis.

Tanshinone Alleviates UVA-induced Melanogenesis in Melanocytes via the Nrf2-regulated Antioxidant Defense Signaling Pathway.

As a complex of natural plant compounds, tanshinone is renowned for its remarkable antioxidant properties. However, the potential impact of tanshinone on melanocyte pigmentation regulation has yet to be elucidated. This study aimed to explore the protective effects of tanshinone I (T-I) and dihydrotanshinone (DHT) on melanogenesis by modulating nuclear factor E2-related factor 2 (Nrf2) signaling and antioxidant defenses in human epidermal melanocyte (HEM) cells. HEM cells and Nrf2 knockdown HEM cells were subjected to ultraviolet A (UVA) and treated with T-I and/or DHT. Then, the anti-melanogenic properties of T-I and DHT were examined by assessing tyrosinase activity, melanogenesis-related proteins, and melanin content in UVA-irradiated HEM cells. Furthermore, the antioxidant activities of T-I and DHT were evaluated by assessing oxidant formation and modulation of Nrf2-related antioxidant defenses, including reactive oxygen species (ROS), glutathione (GSH) content, and the activity and expression of antioxidant enzymes, such as catalase (CAT), heme oxygenase-1 (HO-1), and superoxide dismutase (SOD). Our findings revealed that T-I and DHT diminished melanogenesis in UVAirradiated HEM cells, activated Nrf2-antioxidant response element signaling, and enhanced antioxidant defenses in the irradiated cells. Furthermore, Nrf2 knockdown by shRNA abolished the anti-melanogenesis effects of T-I and DHT on HEM cells against oxidative damage. These results suggest that T-I and DHT inhibit UVA-induced melanogenesis in HEM cells, possibly through redox mechanisms involving Nrf2 signaling activation and increased antioxidant defenses. This indicates that T-I and DHT have potential as whitening agents in cosmetics and medical treatments for hyperpigmentation disorders.

Identification of antioxidant peptides targeting Keap1−Nrf2−ARE pathway from in vitro digestion of pork sausage with partial substitution of NaCl by KCl

The Kelch-like ECH-associated protein 1 (Keap1)–nuclear factor erythroid 2–related factor 2 (Nrf2)–antioxidant response elements (ARE) pathway is one of the most important cellular defense mechanisms against oxidative stress. This study focuses on finding antioxidant peptides from in vitro digestion products of pork sausage with partial substitution of NaCl by KCl by virtual screening. Six antioxidant peptides, LIVGFPAYGH, DWWGSTVR, WNSLLIR, IVGFPAYGH, FDNLWDQGL, and LRSPSWDPF, could activate the Keap1–Nrf2–ARE pathway and protect cells from oxidative stress. DWWGSTVR exhibits the most robust activity among them. Further studies indicated that DWWGSTVR could increase the expression of many antioxidant enzymes by enabling the transfer of Nrf2 from the cytoplasm to the nucleus. In summary, these six peptides are proven to be Nrf2 activators and could be used as functional foods to prevent and treat various oxidative stress-induced diseases.

Acute Oxidative Stress Can Paradoxically Suppress Human NRF2 Protein Synthesis by Inhibiting Global Protein Translation.

The NRF2 transcription factor is a master regulator of the cellular oxidant/electrophile response and a drug target for the prevention/treatment of chronic diseases. A major mechanism of NRF2 activation is its escape from rapid degradation, and newly synthesized NRF2 induces cytoprotective protein expression through its cognate antioxidant response elements (AREs). However, oxidative stress can also inhibit global protein translation, thereby potentially inhibiting NRF2 protein accumulation. H2O2 has been shown to be a relatively weak inducer of NRF2 in comparison with electrophiles. In the current study, we evaluated whether levels of H2O2 that activate the NRF2/ARE pathway inhibit NRF2 protein synthesis in HaCaT keratinocytes. A weak maximum induction was observed for H2O2 in comparison with electrophiles, both for NRF2 protein accumulation and ARE reporter activation (~10-fold compared to ≥100-fold activation). At similar H2O2 concentrations, both NRF2 protein synthesis and global protein synthesis were inhibited. The manganese porphyrin antioxidant MnTMPyP rescued both global protein synthesis and NRF2 protein synthesis from H2O2 inhibition and increased ARE reporter activation. Similar results were observed for the diphenol di-tert-butylhydroquinone (dtBHQ). In conclusion, induction of the NRF2/ARE pathway by H2O2 and dtBHQ-derived oxidative species can be limited by inhibition of NRF2 protein synthesis, likely by arrest of global protein synthesis.

Pyrroloquinoline quinone alleviates natural aging-related osteoporosis via a novel MCM3-Keap1-Nrf2 axis-mediated stress response and Fbn1 upregulation.

Age-related osteoporosis is associated with increased oxidative stress and cellular senescence. Pyrroloquinoline quinone (PQQ) is a water-soluble vitamin-like compound that has strong antioxidant capacity; however, the effect and underlying mechanism of PQQ on aging-related osteoporosis remain unclear. The purpose of this study was to investigate whether dietary PQQ supplementation can prevent osteoporosis caused by natural aging, and the potential mechanism underlying PQQ antioxidant activity. Here, we found that when 6-month-old or 12-month-old wild-type mice were supplemented with PQQ for 12 months or 6 months, respectively, PQQ could prevent age-related osteoporosis in mice by inhibiting osteoclastic bone resorption and stimulating osteoblastic bone formation. Mechanistically, pharmmapper screening and molecular docking studies revealed that PQQ appears to bind to MCM3 and reduces its ubiquitination-mediated degradation; stabilized MCM3 then competes with Nrf2 for binding to Keap1, thus activating Nrf2-antioxidant response element (ARE) signaling. PQQ-induced Nrf2 activation inhibited bone resorption through increasing stress response capacity and transcriptionally upregulating fibrillin-1 (Fbn1), thus reducing Rankl production in osteoblast-lineage cells and decreasing osteoclast activation; as well, bone formation was stimulated by inhibiting osteoblastic DNA damage and osteocyte senescence. Furthermore, Nrf2 knockout significantly blunted the inhibitory effects of PQQ on oxidative stress, on increased osteoclast activity and on the development of aging-related osteoporosis. This study reveals the underlying mechanism of PQQ's strong antioxidant capacity and provides evidence for PQQ as a potential agent for clinical prevention and treatment of natural aging-induced osteoporosis.

Nrf2 targeting in overcoming ferroptosis evasion in head and neck cancer

Ferroptosis is a recently identified type of regulated cell death characterized by lipid peroxidation and redox-active iron accumulation. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a crucial regulator of genes involved in glutathione biosynthesis, antioxidant responses, lipid metabolism, and iron metabolism, contributing to the evasion of ferroptosis. Inhibiting the Nrf2 pathway has been shown to sensitize cancer cells to ferroptosis. In head and neck cancer cells, we found that activation of the Nrf2-antioxidant responsive element pathway leads to ferroptosis resistance, and inhibiting this pathway reverses ferroptosis evasion. Our study suggests that modulating the Nrf2 pathway could be a promising strategy to overcome resistance in cancer therapy for head and neck cancer. Further research is required to investigate the potential of ferroptosis induction in therapy-resistant head and neck cancer. Targeting Nrf2 through ferroptosis-based cancer therapy may be a novel and effective approach to reverse the resistance of head and neck cancer therapy.

Methyl cellosolve-induced hepatic oxidative stress: The modulatory effect of syringic acid on Nrf2-Keap1-Hmox1-NQO1 signaling pathway in rats

Ethnopharmacological relevanceSyringic acid (SAC) is a phenolic compound and an antioxidant that has been identified in honey, grapes, red wine, marigold and sugar apple. Due to its potent antioxidant prowess, SAC possesses hepatoprotective, nephroprotective, neuroprotective, cardioprotective and anti-inflammatory activities. Aim of the studyJudging by these credentials, this study investigated the effect of 25, 50 and 75 mg/kg body weight of SAC on hepatotoxicity induced by 100 mg/kg body weight of methyl cellosolve (MECE) in male Wistar rats. ResultsCompared with control, MECE decreased the liver relative weight, nitric oxide (NO) concentration, glutathione S-transferase (GST), glutathione peroxidase (GPx), catalase (CAT) and superoxide dismutase (SOD) activities, while liver malondialdehyde (MDA), nuclear factor erythroid 2-related factor 2 (Nrf2), Kelch-like ECH associated protein 1 (Keap1), heme oxygenase 1 (Hmox1) and NAD(P)H quinone oxidoreductase 1 (NQO1) levels were significantly increased. Treatments with 25, 50 and 75 mg/kg of SAC significantly decreased the concentration of MDA, Nrf2, Keap1 (by 50 and 75 mg/kg only), mRNA expressions of Hmox1, NQO1 and increased the concentration of NO, activities of GPx, GST, SOD and CAT compared with MECE only administered rats. ConclusionIn conclusion, SAC demonstrated a strong hepatoprotective role against MECE-induced hepatic depletion of endogenous antioxidant enzymes and inhibition of MECE-induced cytosolic Nrf2 activation and antioxidant response element (ARE)-dependent genes in rats.

UBE2E2 enhances Snail-mediated epithelial-mesenchymal transition and Nrf2-mediated antioxidant activity in ovarian cancer

Dissemination of ovarian cancer (OvCa) cells can lead to inoperable metastatic lesions in the bowel and omentum, which have a poor prognosis despite surgical and chemotherapeutical options. A better understanding of the mechanisms underlying metastasis is urgently needed. In this study, bioinformatics analyses revealed that UBE2E2, a less-studied ubiquitin (Ub)-conjugating enzyme (E2), was upregulated in OvCa and was associated with poor prognosis. Subsequently, we performed western blot analysis and IHC staining with 88 OvCa and 26 normal ovarian tissue samples, which further confirmed that UBE2E2 protein is highly expressed in OvCa tissue but weakly expressed in normal tissue. Furthermore, the silencing of UBE2E2 blocked OvCa cell migration, epithelial-mesenchymal transition (EMT) and metastasis in vitro, whereas UBE2E2 overexpression exerted the opposite effects. Mechanistically, UBE2E2 promoted p62 accumulation and increased the activity of the Nrf2-antioxidant response element (ARE) system, which ultimately activated the Snail signaling pathway by inhibiting the ubiquitin-mediated degradation of Snail. Additionally, co-IP and immunofluorescence demonstrated that a direct interaction exists between UBE2E2 and Nrf2, and the N-terminal of UBE2E2 (residues 1-52) is required and sufficient for its interaction with Nrf2 protein. Mutations in the active site cysteine (Cys139) impaired both the function and cellular distribution of UBE2E2. More importantly, the deletion of UBE2E2 reduced tumorigenicity and metastasis in xenograft OvCa mouse models. Taken together, our findings reveal the role of the UBE2E2-Nrf2-p62-Snail signaling axis in OvCa and thus provides novel therapeutic targets for the prevention of OvCa metastasis.

Blockage of Nrf2 and autophagy by L-selenocystine induces selective death in Nrf2-addicted colorectal cancer cells through p62-Keap-1-Nrf2 axis

Persistent Nrf2 activation is typically noted in many cancers, including colorectal cancer (CRC), aiding cancer cells in overcoming growth stress and promoting cancer progression. Sustained Nrf2 activation, which is beneficial for cancer cells, is called “Nrf2 addiction”; it is closely associated with malignancy and poor prognosis in patients with cancer. However, Nrf2 inhibitors may have adverse effects on normal cells. Here, we found that the selenocompound l-selenocystine (SeC) is selectively cytotoxic in the Nrf2-addicted CRC cell line WiDr cells, but not in non–Nrf2-addicted mesenchymal stem cells (MSCs) and normal human colon cells. Another CRC cell line, C2BBe1, which harbored lower levels of Nrf2 and its downstream proteins were less sensitive to SeC, compared with the WiDr cells. We further demonstrated that SeC inhibited Nrf2 and autophagy activation in the CRC cells. Antioxidant GSH pretreatment partially rescued the CRC cells from SeC-induced cytotoxicity and Nrf2 and autophagy pathway inhibition. By contrast, SeC activated Nrf2 and autophagy pathway in non–Nrf2-addicted MSCs. Transfecting WiDr cells with Nrf2-targeting siRNA decreased persistent Nrf2 activation and alleviated SeC cytotoxicity. In KEAP1-knockdown C2BBe1 cells, Nrf2 pathway activation increased SeC sensitivity and cytotoxicity. In conclusion, SeC selectively attacks cancer cells with constitutively activated Nrf2 by reducing Nrf2 and autophagy pathway protein expression through the P62–Nrf2–antioxidant response element axis and eventually trigger cell death.

Verniciflavanol A, a profisetinidin-type-4-arylflavan-3-ol from toxicodendron vernicifluum protects SH-SY5Y cells against H2O2-Induced oxidative stress

Eleven undescribed derivatives of flavan, including flavan-3,4-diols vernicinosides A-H and profisetinidin-type-4-arylflavan-3-ols verniciflavanols A-C, together with eight known compounds were purified from the heartwood of Toxicodendron vernicifluum. The chemical structures of the undescribed compounds were characterized by spectroscopic data interpretation, including NMR (1H and 13C NMR HSQC and HMBC) and HRESIMS analysis. CD data analysis was conducted to assign the absolute configurations of the undescribed compounds and the active compound verniciflavanol A was also confirmed by ECD experiment. The absolute configuration of the sugar moiety was identified by GC analysis of chiral derivatives in the hydrolysate. MTT assay was applied to test these compounds against H2O2-induced oxidative stress in human neuroblastoma SH-SY5Y cells. Results found that verniciflavanol A demonstrated the best potential in protecting SH-SY5Y cells against H2O2-induced oxidative stress by inhibiting cell apoptosis and attenuate reactive oxygen species (ROS) level and mitochondrial dysfunction. And the underlying mechanism was confirmed to be associated with Nrf2-antioxidant response element signaling and IL-6 cell survival pathways.

Modulation of Nrf2 by activation of estrogen receptor β as a therapeutic strategy to prevent cancer development and overcome inflammation-related drug resistance in breast cancer

Despite the tremendous progress in breast cancer diagnosis and treatment, the mortality rate is expected to increase due to the emergence of drug resistance. Pro-inflammatory markers are thought to contribute to drug resistance by activation of its naive receptors and its downstream signaling pathways. Elevation of pro-inflammatory markers leads to an increase in the biosynthesis of estrogen which can promote the proliferation of estrogen receptor (ER)+ breast cancer. Inflammation also results in obesity which is one of the key risk factors. Estrogen receptor-beta (ER-β) is an important target that has been widely studied and accepted to possess anti-cancer activity in a number of cancers including breast cancer. ER-β elicits its action through genomic and non-genomic pathways. The genomic pathway increases the transcription of potent cyclin-dependent kinase inhibitor (p21), and tumor suppressor genes such as melanoma differentiation associated gene 7 and tumor protein (p53). The non-genomic pathway works through protein-protein interaction and phosphorylation. Here, we propose that the activation of ER-β might enhance the activation of nuclear factor-erythroid factor 2-related factor 2 (Nrf2) via estrogen receptor-alpha (ER-α) repression. The activation of Nrf2 increases the transcription of antioxidant genes such as NADH quinone oxidoreductase 1 (NQO1), heme oxygenase-1 (HO-1), etc., and decreases the expression of pro-inflammatory genes such as tumor necrosis factor-α (TNF-α), interleukin-1 (IL-1), etc. This review hypothesizes and suggests that ER-β agonists could play a beneficial role to overcome inflammation-related drug resistance by modulation of the Nrf2/antioxidant response element (Nrf2/ARE) pathway.

CSurvival: a web resource for biomarker interactions in cancer outcomes and in cell lines.

Survival analysis is a technique for identifying prognostic biomarkers and genetic vulnerabilities in cancer studies. Large-scale consortium-based projects have profiled >11 000 adult and >4000 pediatric tumor cases with clinical outcomes and multiomics approaches. This provides a resource for investigating molecular-level cancer etiologies using clinical correlations. Although cancers often arise from multiple genetic vulnerabilities and have deregulated gene sets (GSs), existing survival analysis protocols can report only on individual genes. Additionally, there is no systematic method to connect clinical outcomes with experimental (cell line) data. To address these gaps, we developed cSurvival (https://tau.cmmt.ubc.ca/cSurvival). cSurvival provides a user-adjustable analytical pipeline with a curated, integrated database and offers three main advances: (i) joint analysis with two genomic predictors to identify interacting biomarkers, including new algorithms to identify optimal cutoffs for two continuous predictors; (ii) survival analysis not only at the gene, but also the GS level; and (iii) integration of clinical and experimental cell line studies to generate synergistic biological insights. To demonstrate these advances, we report three case studies. We confirmed findings of autophagy-dependent survival in colorectal cancers and of synergistic negative effects between high expression of SLC7A11 and SLC2A1 on outcomes in several cancers. We further used cSurvival to identify high expression of the Nrf2-antioxidant response element pathway as a main indicator for lung cancer prognosis and for cellular resistance to oxidative stress-inducing drugs. Altogether, these analyses demonstrate cSurvival’s ability to support biomarker prognosis and interaction analysis via gene- and GS-level approaches and to integrate clinical and experimental biomedical studies.

Swertiamarin ameliorates inflammation and oxidative damage in autoimmune encephalomyelitis mouse model

Multiple sclerosis (MS) is a degenerative autoimmune disease attacks the myelin sheath of the central nervous system (CNS) neurons causing different disabilities. According to recent evidence, the main bioactive component in Enicostema axillare, the Swrtiamarin (SM) has been found to exert anti-inflammatory and antioxidant activities against several diseases. However, SM activities in treatment of autoimmune diseases remain to be explored. Herein, we used a murine model of MS, to show that SM treatment ameliorates the severity of experimental autoimmune encephalomyelitis (EAE). This occurs through reducing the levels of pro-inflammatory cytokines and infiltration of CD4+CD45+ cells into CNS. That was associated with a reduction in the expression of STAT3 and NFkB in CD4+ T cells under Th17 and LPS-stimulated macrophages. Furthermore, in silico studies revealed that SM interacts with NF-E2-related factor 2 (NRF2), and therefore, suppressed oxidative stress by inducing formation NRF2-antioxidant response element (ARE) complex. We found that SM is an agonist of NRF2 complex regulating the total CD4 population and antioxidant markers in EAE mice. Molecular docking analysis showed a stable and higher binding affinity between SM and NRF2. Results revealed that SM treatment increased the complex formation between ARE and NRF2 where immunoprecipitation methods showed a higher binding affinity of ARE to NRF2 in SM treated animals. Complex formation triggered ARE cascade of antioxidant gene clusters and reduces the MS pathological alterations in EAE mice model. Current data proposed SM as an effective biomolecule in treatment of MS and controlling neuronal damage through inhibiting oxidative stress markers and targeting NRF2.

Morphine-induced modulation of Nrf2-antioxidant response element signaling pathway in primary human brain microvascular endothelial cells

Morphine is one of the most potent opioid analgesic used for pain treatment. Morphine action in the central nervous system requires crossing the blood–brain barrier. Due to the controversial relationship between morphine and oxidative stress, the potential pro- or antioxidant effects of morphine in the blood–brain barrier is important to be understood, as oxidative stress could cause its disruption and predispose to neurodegenerative diseases. However, investigation is scarce in human brain endothelial cells. Therefore, the present study evaluated the impact of morphine exposure at three different concentrations (1, 10 and 100 µM) for 24 h and 48 h on primary human brain microvascular endothelial cells. A quantitative data-independent acquisition mass spectrometry strategy was used to analyze proteome modulations. Almost 3000 proteins were quantified of which 217 were reported to be significantly regulated in at least one condition versus untreated control. Pathway enrichment analysis unveiled dysregulation of the Nrf2 pathway involved in oxidative stress response. Seahorse assay underlined mitochondria dysfunctions, which were supported by significant expression modulations of relevant mitochondrial proteins. In conclusion, our study revealed the dysregulation of the Nrf2 pathway and mitochondria dysfunctions after morphine exposure, highlighting a potential redox imbalance in human brain endothelial cells.

Upregulation of nuclear factor E2-related factor 2 (Nrf2) represses the replication of herpes simplex virus type 1

BackgroundNuclear factor E2-related factor 2 (Nrf2) is an important transcription factor which plays a pivotal role in detoxifying reactive oxygen species (ROS) and has been more recently shown to regulate inflammatory and antiviral responses. However, the role of Nrf2 in Herpes Simplex Virus type 1 (HSV-1) infection is still unclear. In this study, the interaction between the Nrf2 and HSV-1 replication was investigated.MethodsThe levels of oxidative stress was monitored by using 8-hydroxy-2'-deoxyguanosine (8-OHdG) ELISA kits, and the dynamic changes of Nrf2-antioxidant response element (Nrf2-ARE) pathway were detected by Western Blot. The effect of Nrf2-ARE pathway on the regulation of HSV-1 proliferation was analyzed by Western Blot, Real-Time PCR and TCID50 assay.ResultsHSV-1 infection induced oxidative stress. Nrf2 was activated, accompanied by the increase of its down-stream antioxidant enzyme heme oxygenase-1 (HO-1) and NAD(P)H quinone oxidoreductase 1 (NQO1) in the early stage of HSV-1 infection. The proliferation of HSV-1 was inhibited by overexpression of Nrf2 or treatment with its activator tert-Butylhydroquinone (tBHQ). On the contrary, silencing of Nrf2 promotes virus replication. HO-1 is involved in the regulation of IFN response, leading to efficient anti-HSV-1 effects.ConclusionOur observations indicate that the Nrf2-ARE pathway activates a passive defensive response in the early stage of HSV-1 infection. Targeting the Nrf2 pathway demonstrates the potential for combating HSV-1 infection.

Assessment of Protection Offered By the NRF2 Pathway Against Hyperoxia-Induced Acute Lung Injury in NRF2 Knockout Rats.

Nuclear factor erythroid 2-related factor (Nrf2) is a redox-sensitive transcription factor that responds to oxidative stress by activating expressions of key antioxidant and cytoprotective enzymes via the Nrf2-antioxidant response element (ARE) signaling pathway. Our objective was to characterize hyperoxia-induced acute lung injury (HALI) in Nrf2 knock-out (KO) rats to elucidate the role of this pathway in HALI. Adult Nrf2 wildtype (WT), and KO rats were exposed to room air (normoxia) or >95% O2 (hyperoxia) for 48 h, after which selected injury and functional endpoints were measured in vivo and ex vivo. Results demonstrate that the Nrf2-ARE signaling pathway provides some protection against HALI, as reflected by greater hyperoxia-induced histological injury and higher pulmonary endothelial filtration coefficient in KO versus WT rats. We observed larger hyperoxia-induced increases in lung expression of glutathione (GSH) synthetase, 3-nitrotyrosine (index of oxidative stress), and interleukin-1β, and in vivo lung uptake of the GSH-sensitive SPECT biomarker 99mTc-HMPAO in WT compared to KO rats. Hyperoxia also induced increases in lung expression of myeloperoxidase in both WT and KO rats, but with no difference between WT and KO. Hyperoxia had no effect on expression of Bcl-2 (anti-apoptotic protein) or peroxiredoxin-1. These results suggest that the protection offered by the Nrf2-ARE pathway against HALI is in part via its regulation of the GSH redox pathway. To the best of our knowledge, this is the first study to assess the role of the Nrf2-ARE signaling pathway in protection against HALI using a rat Nrf2 knockout model.

Molecular and functional characterization of MST2 in grass carp during bacterial infection

The regulation of host redox homeostasis is critically important in the immune response to pathogens. The “mammalian sterile 20-like” kinase 2 (MST2) has been shown to play a role in apoptosis, cell proliferation, and cancer; however, few studies have examined its ability to modulate redox homeostasis during innate immunity, especially in teleost fish. In this study, we cloned the MST2 gene of Ctenopharyngodon idella (CiMST2) and analyzed its tissue distribution. CiMST2 was present in most of the studied tissues, and it was most highly expressed in brain tissue. Expression patterns analysis revealed that MST2 mRNA and protein were significantly up-regulated under bacterial infection, suggesting that it is involved in the immune response. Bacterial stimulation significantly increased the level of antioxidases. To explore the interplay between CiMST2 and antioxidant regulation, we examined the effects of CiMST2 overexpression and conducted RNA interference assays in vitro. CiMST2 overexpression significantly increased the expression levels of nuclear factor E2-related factor 2 (Nrf2) and other antioxidases and vice versa, revealing that CiMST2 regulated host redox homeostasis via Nrf2-antioxidant responsive element (ARE) signaling. Overall, our findings provide a new perspective on the role of MST2 in innate immunity in teleosts as well as insights that will aid the prevention and control of disease in the grass carp farming industry.

Glutathione and Related Molecules in Parkinsonism

Glutathione (GSH) is the most abundant intrinsic antioxidant in the central nervous system, and its substrate cysteine readily becomes the oxidized dimeric cystine. Since neurons lack a cystine transport system, neuronal GSH synthesis depends on cystine uptake via the cystine/glutamate exchange transporter (xCT), GSH synthesis, and release in/from surrounding astrocytes. Transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2), a detoxifying master transcription factor, is expressed mainly in astrocytes and activates the gene expression of various phase II drug-metabolizing enzymes or antioxidants including GSH-related molecules and metallothionein by binding to the antioxidant response element (ARE) of these genes. Accumulating evidence has shown the involvement of dysfunction of antioxidative molecules including GSH and its related molecules in the pathogenesis of Parkinson’s disease (PD) or parkinsonian models. Furthermore, we found several agents targeting GSH synthesis in the astrocytes that protect nigrostriatal dopaminergic neuronal loss in PD models. In this article, the neuroprotective effects of supplementation and enhancement of GSH and its related molecules in PD pathology are reviewed, along with introducing new experimental findings, especially targeting of the xCT-GSH synthetic system and Nrf2–ARE pathway in astrocytes.

Rice bran-derived protein fractions enhance sulforaphane-induced anti-oxidative activity in gingival epithelial cells

ObjectiveFood-derived bioactive peptides have been reported to exhibit various beneficial effects, including anti-microbial, anti-inflammatory, and anti-oxidant properties. Oxidative stress has been implicated in the development of several inflammatory diseases such as periodontal disease. However, the anti-oxidative effect of food-derived bioactive peptides in gingival epithelial cells (GECs) is unknown. Therefore, we examined the bioactivity of the peptides in GECs. DesignFood-derived peptide fractionations derived from rice bran, rice endosperm, corn, and soy were screened for anti-oxidative effects using anti-oxidant response element (ARE)-luciferase–transfected HEK 293 cells. The induction of anti-oxidation–related genes and proteins in GECs by the fractions were examined by quantitative PCR and Western blotting, respectively. Then, the fraction-mediated anti-oxidative effects were examined by measuring intracellular reactive oxygen species (ROS) levels using flow cytometry. Furthermore, the anti-oxidative response-related cellular signaling pathways were analyzed via Western blotting. ResultsAlthough treatment with the food-derived peptides alone did not activate anti-oxidative responses, co-treatment with sulforaphane (SFN; a potent anti-oxidant) and certain food-derived peptides enhanced anti-oxidative responses in ARE-luciferase–transfected HEK 293 cells. The fractions augmented heme oxygenase-1 mRNA and protein expression in GECs. The percentage of ROS-positive cells was significantly decreased by co-treatment with SFN and peptide fractions derived from rice bran. Furthermore, the involvement of both nuclear factor erythroid 2-related factor 2 (Nrf2) and extracellular signal-regulated kinase (ERK) in the enhancement of anti-oxidative responses was demonstrated by Western blotting. ConclusionsPeptides derived from rice bran enhances SFN-induced anti-oxidative responses in GECs through ERK–Nrf2–ARE signaling.

A new ferroptosis inhibitor, isolated from Ajuga nipponensis, protects neuronal cells via activating NRF2-antioxidant response elements (AREs) pathway

Ferroptosis is a new form of cell death, and inhibition of ferroptosis is a promising strategy to treat neurological diseases. In this work, sixteen compounds were isolated from Ajuga nipponensis and assayed for anti-ferroptosis activity in HT22 mouse hippocampal neuronal cells. Ajudecunoid C (1, ADC), a new neoclerodane diterpenoid, showed significant inhibitory activity against erastin and RSL3-induced ferroptosis with EC50 values of 4.1 ± 1.0 and 3.6 ± 0.3 μM, respectively. Experimental results demonstrated that ADC effectively prevented ferroptosis through scavenging free radical and activating NRF2-antioxidant response elements (AREs) pathway. This study reveals that ADC, as a new ferroptosis inhibitor, is a promising lead compound for the development of drugs against ferroptosis-related neurological diseases.