Nrf2-ARE Signaling Research Articles

Sesaminol prevents Parkinson's disease by activating the Nrf2-ARE signaling pathway

Parkinson's disease (PD) is a neurodegenerative disease caused by the degeneration of substantia nigra neurons due to oxidative stress. Sesaminol has strong antioxidant and anti-cancer effects. We investigated the preventive effect on PD as a new physiological action of sesaminol produced from sesaminol glycoside using in vitro and in vivo PD models. To prepare an in vitro PD model, 6-hydroxydopamine (6-OHDA) was added to human neuroblastoma (SH-SY5Y cells). The viability of SH-SY5Y cells decreased dose-dependently following 6-OHDA treatment, but the addition of sesaminol restored viability to the control level. 6-OHDA increased intracellular reactive oxygen species production, and the addition of sesaminol significantly suppressed this increase. No Nrf2 expression in the nucleus was observed in the control group, but a slight increase was observed in the 6-OHDA group. The sesaminol group showed strong expression of Nrf2 in the cytoplasm and nucleus. NAD(P)H: quinone oxidoreductase (NQO1) activity was enhanced in the 6-OHDA group and further enhanced in the sesaminol group. Furthermore, the neurotoxine rotenone was orally administrated to mice to prepare an in vivo PD model. The motor function of rotenone-treated mice was shorter than that of the control group, but a small amount of sesaminol restored it to the control level. The intestinal motility in the rotenone group was significantly lower than that in the control group, but it remained at the control level in the sesaminol group. The expression of α-synuclein in the substantia nigra increased in the rotenone group but decreased in the sesaminol group. The rotenone group exhibited shortening and damage to the colonic mucosa, but these abnormalities of the colonic mucosa were scarcely observed in the sesaminol group. These results suggest that sesaminol has a preventative effect on PD.

The Protective Effect of Static Magnetic Fields with Different Magnetic Inductions against Fluoride Toxicity Is Related to the NRF2 Signaling Pathway

A redox imbalance disrupts the cellcycle and the proliferation process, and contributes to the initiation of programmed cell death. One of the pathways that are important for redox homeostasis is the Nrf2-ARE signaling pathway. Fluoride as well as static magnetic fields (SMF) are associated with the concepts of oxidative stress, and thus programmed cell death. Therefore, this study aimed to assess the connection between oxidative stress and apoptosis in human cells co-exposed to fluoride and a SMF with a different magnetic induction and to determine whether the Nrf2-signaling pathway is involved in these effects. The research was realized using normal human dermal fibroblasts that had been co-exposed to fluoride (0.3 mmol/L) and a SMF with a different magnetic induction (0.45 T, 0.55 T, 0.65 T) for 12 h. The mRNA levels of the cellular antioxidant system-related genes and apoptosis-related genes were assessed using the quantitative reverse transcription polymerase chain reaction (RT-qPCR) method. Our results indicated that the increased activity of antioxidant enzymes (SOD1 (superoxide dismutase 1), SOD2 and GSR (glutathione reductase)) suggests the restoration of the cell redox homeostasis that had been disturbed by fluoride, and also that the genes whose expression is associated with the induction of apoptosis are down regulated as a result of exposure to a SMF. The SMF with a 0.65 T flux density had the strongest effect on the fibroblasts. Moreover, our findings demonstrated that the Nrf2 transcription factor plays a crucial role in the protective effect of a SMF against fluoride toxicity in human cells. The results of these studies can form the basis for developing therapeutic strategies for apoptosis and oxidative stress-related diseases.

Curcumin Attenuates Chronic Unpredictable Mild Stress-Induced Depressive-Like Behaviors via Restoring Changes in Oxidative Stress and the Activation of Nrf2 Signaling Pathway in Rats.

Accumulating evidence has demonstrated that oxidative stress is associated with depression. Our present study aimed at investigating the antidepressant effect and the possible mechanisms of curcumin (CUR) in chronic unpredictable mild stress- (CUMS-) induced depression model in rats. After exposure to CUMS for four weeks, the rats showed depressive-like behavior, and the depressive-like behaviors in CUMS-treated rats were successfully corrected after administration of CUR. In addition, CUR could effectively decrease protein expression of oxidative stress markers (Nox2, 4-HNE, and MDA) and increase the activity of CAT. CUR treatment also reversed CUMS-induced inhibition of Nrf2-ARE signaling pathway, along with increasing the mRNA expression of NQO-1 and HO-1. Furthermore, the supplementation of CUR also increased the ratio of pCREB/CREB and synaptic-related protein (BDNF, PSD-95, and synaptophysin). In addition, CUR could effectively reverse CUMS-induced reduction of spine density and total dendritic length. In conclusion, the study revealed that CUR relieves depressive-like state through the mitigation of oxidative stress and the activation of Nrf2-ARE signaling pathway.

Brain Dicer1 Is Down-Regulated in a Mouse Model of Alzheimer's Disease Via Aβ42-Induced Repression of Nuclear Factor Erythroid 2-Related Factor 2.

Dicer1 is a microRNA-processing enzyme which plays critical roles in neuronal survival and neuritogenesis. Dicer1 deletion induces neurodegeneration or degeneration in retinal pigment epithelium, which is associated with oxidative stress. Oxidative stress is thought to be central in the pathogenesis of Alzheimer's disease (AD). Therefore, we hypothesize that Dicer1 may play roles in AD. Using immunoblotting and quantitative real-time PCR, Dicer1 protein and mRNA were reduced in the hippocampi of the AD mouse model APPswe/PSEN1dE9 compared with littermate controls. SiRNA-mediated Dicer1 knockdown induced oxidative stress and apoptosis and reduced mitochondrial membrane potential in cultured neurons. Chronic Aβ42 exposure decreased Dicer1 and nuclear factor erythroid 2-related factor 2 (Nrf2) which were reversed by N-acetyl-cystein. Nrf2 overexpression increased Dicer1 mRNA and protein and reverted the Aβ42-induced Dicer1 reduction. We further cloned Dicer1 promoter variants harboring the Nrf2-binding site, the antioxidant response elements (ARE), into a luciferase reporter and found that simultaneous transfection of Nrf2-expressing plasmid increased luciferase expression from these promoter constructs. ChIP assays indicated that Nrf2 directly interacted with the ARE motifs in the Dicer1 promoter. Furthermore, Dicer1 overexpression in cultured neurons reverted Aβ42-induced neurite deficits. Notably, injection of Dicer1-expressing adenovirus into the hippocampus of the mice significantly improved spatial learning. Altogether, we found novel roles of Dicer1 in AD and a novel regulatory pathway for Dicer1. These results suggest that Dicer1 is a target in AD therapy, especially at the early stage of this disorder. In this study, we found that Dicer1 was reduced in the brain of AD mice which is the first report to examine Dicer1 in AD. We further found (i) that Aβ42 exposure decreased Dicer1 via attenuating Nrf2-ARE signaling and (ii) injection of Dicer1-expressing adenovirus into the hippocampus of the AD mice significantly improved spatial learning. Altogether, we found novel roles of Dicer1 in AD and a novel regulatory pathway for Dicer1. This study may open new avenues for investigating potential pathognomonics and pathogenesis in AD.

Dietary Tribonema sp. supplementation increased growth performance, antioxidant capacity, immunity and improved hepatic health in golden pompano (Trachinotus ovatus)

Filamentous microalga Tribonema sp. contains multiple bioactive compounds, such as eicosapentaenoic acid (EPA), palmitoleic acid and chrysolaminarin. Tribonema sp. is potentially a nature and safe ingredient in aquatic feed. Therefore, 6-week feeding experiment was conducted to investigate the effects of Tribonema sp. on growth performance, antioxidant capacity, immunity and hepatic health of Trachinotus ovatus. Three isonitrogenous and isolipidic diets (TS0, TS1 and TS5) containing 0% (control group), 1% and 5% Tribonema sp. were formulated, respectively. Results indicated that T. ovatus fed with TS5 diet significantly improved the growth performance by enhancing digestive enzyme activities and up-regulating the expression of growth hormone (GH) and insulin-like growth factor (IGF-I). T. ovatus fed with TS5 diet also significantly facilitated the antioxidant capacity through activating the Nrf2-ARE signal pathway and increasing antioxidant enzyme activities. Meanwhile, TS5 diet significantly promoted liver health by upregulating the expression of anti-inflammatory cytokines and downregulating the expression of pro-inflammatory cytokines. Furthermore, TS5 diet also upregulated the expression levels of non-specific immune related genes, including complement 4 (C4), c-type lysozyme (C-Lyz) and heat shock protein 70 (HSP70). In conclusion, Tribonema sp. can be used as feed ingredients to increase growth performance, antioxidant capacity, immunity and improve hepatic health in T. ovatus.

Neuroprotection Against Oxidative Stress: Phytochemicals Targeting TrkB Signaling and the Nrf2-ARE Antioxidant System.

Oxidative stress (OS) plays a critical role in the pathophysiology of several brain-related disorders, including neurodegenerative diseases and ischemic stroke, which are the major causes of dementia. The Nrf2-ARE (nuclear factor erythroid 2-related factor 2/antioxidant responsive element antioxidant) system, the primary cellular defense against OS, plays an essential role in neuroprotection by regulating the expressions of antioxidant molecules and enzymes. However, simultaneous events resulting in the overproduction of reactive oxygen species (ROS) and deregulation of the Nrf2-ARE system damage essential cell components and cause loss of neuron structural and functional integrity. On the other hand, TrkB (tropomyosin-related kinase B) signaling, a classical neurotrophin signaling pathway, regulates neuronal survival and synaptic plasticity, which play pivotal roles in memory and cognition. Also, TrkB signaling, specifically the TrkB/PI3K/Akt (TrkB/phosphatidylinositol 3 kinase/protein kinase B) pathway promotes the activation and nuclear translocation of Nrf2, and thus, confers neuroprotection against OS. However, the TrkB signaling pathway is also known to be downregulated in brain disorders due to lack of neurotrophin support. Therefore, activations of TrkB and the Nrf2-ARE signaling system offer a potential approach to the design of novel therapeutic agents for brain disorders. Here, we briefly overview the development of OS and the association between OS and the pathogenesis of neurodegenerative diseases and brain injury. We propose the cellular antioxidant defense and TrkB signaling-mediated cell survival systems be considered pharmacological targets for the treatment of neurodegenerative diseases, and review the literature on the neuroprotective effects of phytochemicals that can co-activate these neuronal defense systems.

Mitochondrial alterations triggered by repeated exposure to fine (PM2.5-0.18) and quasi-ultrafine (PM0.18) fractions of ambient particulate matter

Nowadays ambient particulate matter (PM) levels still regularly exceed the guideline values established by World Health Organization in most urban areas. Numerous experimental studies have already demonstrated the airway toxicity of the fine fraction of PM (FP), mainly triggered by oxidative stress-induced airway inflammation. However, only few studies have actually paid close attention to the ultrafine fraction of PM (UFP), which is likely to be more easily internalized in cells and more biologically reactive. Mitochondria are major endogenous sources of reactive oxygen species (ROS) through oxidative metabolism, and coordinate many critical cellular signaling processes. Mitochondria have been often studied in the context of PM toxicity and generally associated with apoptosis activation. However, little is known about the underlying adaptation mechanisms that could occur following exposure at sub-apoptotic doses of ambient PM. Here, normal human bronchial epithelial BEAS-2B cells were acutely or repeatedly exposed to relatively low doses (5 µg.cm−2) of FP (PM2.5-0.18) or quasi-UFP (Q-UFP; PM0.18) to better access the critical changes in mitochondrial morphology, functions, and dynamics. No significant cytotoxicity nor increase of apoptotic events were reported for any exposure. Mitochondrial membrane potential (ΔΨm) and intracellular ATP content were also not significantly impaired. After cell exposure to sub-apoptotic doses of FP and notably Q-UFP, oxidative phosphorylation was increased as well as mitochondrial mass, resulting in increased production of mitochondrial superoxide anion. Given this oxidative boost, the NRF2-ARE signaling pathway was significantly activated. However, mitochondrial dynamic alterations in favor of accentuated fission process were observed, in particular after Q-UFP vs FP, and repeated vs acute exposure. Taken together, these results supported mitochondrial quality control and metabolism dysfunction as an early lung underlying mechanism of toxicity, thereby leading to accumulation of defective mitochondria and enhanced endogenous ROS generation. Therefore, these features might play a key role in maintaining PM-induced oxidative stress and inflammation within lung cells, which could dramatically contribute to the exacerbation of inflammatory chronic lung diseases. The prospective findings of this work could also offer new insights into the physiopathology of lung toxicity, arguably initiate and/or exacerbate by acutely and rather repeated exposure to ambient FP and mostly Q-UFP.

Hepatoprotective and Anti-Oxidative Effects of Total Flavonoids From Qu Zhi Qiao (Fruit of Citrus Paradisi cv.Changshanhuyou) on Nonalcoholic Steatohepatitis In Vivo and In Vitro Through Nrf2-ARE Signaling Pathway.

Nonalcoholic steatohepatitis (NASH) is a liver disease defined as the dynamic condition of hepatocellular injury during the progress of nonalcoholic fatty liver disease (NAFLD). Total flavonoids from the dry and immature fruits of Citrus Paradisi cv.Changshanhuyou (accepted species name: Citrus × aurantium L) (Qu Zhi Qiao, QZQ) are purified and named TFCH. This study was purposed to investigate and analyze the effect of TFCH on NASH model through Nuclear factor erythroid 2-related factor 2 (Nrf2)- antioxidant response elements pathway in vivo and in vitro. In vivo study was performed using male C57BL/6 mice fed with high fat diet 16 weeks for NASH model. After 7-week modeling, mice in TFCH-treated group were daily treated with intragastric administration of TFCH at 25 mg/kg, 50 mg/kg, 200 mg/kg, respectively, for successive 8 weeks. Histopathological and immunohistochemical analyses were conducted for evaluating severity of NASH-mice model and the effect of TFCH treatment. In vitro experiment was performed by using human LX-2 cells and cultured with Free fatty acid (FFA) (Oleic acid: palmitic: l: 0.5 mmol/L) for 24 h and then treated with TFCH at different concentrations (0, 25, 50, 100, 200 mg/ml) for 6 h,12 h, and 24 h. Anti-apoptosis effect of TFCH on LX-2 cells cultured with FFA was revealed by the CCK-8 assay. Lipid parameters and oxidative stress markers were measured in vivo and in vitro, results showed that TFCH dose-dependently and greatly increased the antioxidant ability and reduced the oxidative damage in NASH model. The protein expression of Nrf2 and the downstream target genes in mice liver and human LX-2 cells were tested by Western blot analysis to investigate the possible molecular mechanisms of TFCH. Our results indicated that TFCH up-regulated protein expression of these genes and have the significant influence in activating the Nrf2-ARE signaling pathway. This study shows Nrf2-ARE signaling pathway may provide novel therapeutic opportunities for NASH therapy in the future.

Perilipin 5 Reduces Oxidative Damage Associated With Lipotoxicity by Activating the PI3K/ERK-Mediated Nrf2-ARE Signaling Pathway in INS-1 Pancreatic β-Cells.

Oxidative stress induced by free fatty acid overload in pancreatic β-cells is a potential contributory factor to dysfunction of insulin secretion and apoptotic cell death. Perilipin 5 (Plin5) has been reported to ameliorate oxidative stress-mediated damage in non-insulin-secreting tissues. We tested the hypothesis that Plin5 plays a similar role in pancreatic β-cells, which are extremely sensitive to oxidative stress. Here, our in vitro data showed that Plin5-mediated alleviation of palmitate-triggered apoptosis involves the mitochondrial pathway. And the protective role of Plin5 on β-cells was partially dependent on its modulation in oxidative stress. Upregulation of Plin5 in INS-1 cells decreased reactive oxygen species production, enhanced cellular glutathione levels, and induced expression of antioxidant enzymes glutamate-cysteine ligase catalytic subunit and heme oxygenase-1. However, knocking out of Plin5 abolished all of these beneficial effects. Furthermore, by using the O2− scavenger MnTMPyP, we verified that altering Plin5 expression impacted lipotoxic cell death partially via modulating oxidative stress. Mechanistic experiments revealed that Plin5 induced Nrf2-ARE system, a master regulator in the cellular adaptive response to oxidative stress, by activating PI3K/Akt and ERK signal pathways, contributing to the increase of antioxidant defense and consequently improving β-cell function and survival in the presence of lipotoxic oxidative stress. Overall, our findings indicate that Plin5 abrogates oxidative damage in INS-1 β-cells during lipotoxic stress partially through the enhancement of antioxidant defense involving the PI3K/Akt and ERK mediated Nrf2-ARE system.

The expression of Nrf2-ARE signaling pathway combined with plasma platelet activating factor in elderly patients with respiratory failure and its correlation with lung function.

The expression of Nrf2-ARE signaling pathway combined with plasma platelet activating factor in elderly patients with respiratory failure and its correlation with lung function.

Farrerol Directly Targets GSK-3β to Activate Nrf2-ARE Pathway and Protect EA.hy926 Cells against Oxidative Stress-Induced Injuries.

Oxidative stress-mediated endothelial injury is considered to be involved in the pathogenesis of various cardiovascular diseases. Farrerol, a typical natural flavanone from the medicinal plant Rhododendron dauricum L., has been reported to show protective effects against oxidative stress-induced endothelial injuries in our previous study. However, its action molecular mechanisms and targets are still unclear. In the present study, we determined whether farrerol can interact with glycogen synthase kinase 3β- (GSK-3β-) nuclear factor erythroid 2-related factor 2- (Nrf2-) antioxidant response element (ARE) signaling, which is critical in defense against oxidative stress. Our results demonstrated that farrerol could specifically target Nrf2 negative regulator GSK-3β and inhibit its kinase activity. Mechanistic studies proved that farrerol could induce an inhibitory phosphorylation of GSK-3β at Ser9 without affecting the expression level of total GSK-3β protein and promote the nuclear translocation of Nrf2 as well as the mRNA and protein expression of its downstream target genes heme oxygenase-1 (HO-1) and NAD(P)H: quinone oxidoreductase 1 (NQO1) in EA.hy926 cells. Further studies performed with GSK-3β siRNA and specific inhibitor lithium chloride (LiCl) confirmed that GSK-3β inhibition was involved in farrerol-mediated endothelial protection and Nrf2 signaling activation. Moreover, molecular docking and molecular dynamics studies revealed that farrerol could bind to the ATP pocket of GSK-3β, which is consistent with the ATP-competitive kinetic behavior. Collectively, our results firstly demonstrate that farrerol could attenuate endothelial oxidative stress by specifically targeting GSK-3β and further activating the Nrf2-ARE signaling pathway.

Prominence of Oxidative Stress in the Management of Anti-tuberculosis Drugs Related Hepatotoxicity.

Advanced medical services and treatments are available for treating Tuberculosis. Related prevalence has increased in recent times. Unfortunately, the continuous consumption of related drugs is also known for inducing hepatotoxicity which is a critical condition and cannot be overlooked. The present review article has focused on the pathways causing these toxicities and also the role of enzyme CYP2E1, hepatic glutathione, Nrf2-ARE signaling pathway, and Membrane Permeability Transition as possible targets which may help in preventing the hepatotoxicity induced by the drugs used in the treatment of tuberculosis.

Sevoflurane suppresses oxidation-induced stress and inflammatory responses, via promotion of Nrf2-induced antioxidant signaling

This study aimed to investigate the role of sevoflurane on anti-oxidant effects in sepsis-induced multiple organ failure. Western blot and quantitative RT–PCR were used to measure the expression of Nrf2 and its downstream genes. The DCFH-DA fluorescence probe assay was performed to assess the intracellular levels in HUVECs and LMVECs. Electrophoretic mobility shift assay was used to assess the DNA binding activities of Nrf2. Better survival, reduced expression of inflammatory cytokines, and improved pathological infiltration in the lungs and kidneys were observed in septic rats treated with sevoflurane. SOD activity increased and Nrf2–ARE signaling pathway was activated following sevoflurane treatment. The protective effect was lost in sepsis-induced acute lung injury (ALI) following inhibition of Nrf2 by intratracheal delivery of siRNA-Nrf2. In vitro experiments, we found the sevoflurane could suppress ROS production after stimulation with LPS and the application of sevoflurane augments the DNA-binding activity of Nrf2 in HUVECs and LMVECs. However, knockdown of Nrf2 by siRNA-Nrf2, the Protein kinase C (PKC) inhibitor, and the Nrf2 inhibitor ML385 could partially recover ROS production, inhibit the activity of SOD, and repress the expression of anti-oxidant genes following sevoflurane treatment. Sevoflurane could have protective effects in ALI and septic multiple organ disorders (MODs).

Resveratrol ameliorates rheumatoid arthritis via activation of SIRT1‐Nrf2 signaling pathway

The present study was designed to explore the biological role of resveratrol (RES) in rheumatoid arthritis (RA) and the underlying mechanism. The adjuvant-induced arthritic rats were administered RES on the 12th day after model establishment, and then arthritis assessment, oxidative stress measurement, histological examination, and immunohistochemical staining were performed. The primary rat fibroblast-like synoviocytes (FLS) were isolated and treated with RES in vitro and then cell proliferation and apoptosis assay were examined. Chromatin immunoprecipitation assay, luciferase reporter assay, intracellular reactive oxygen species (ROS) determination, western blot, and quantitative real time-polymerase chain reaction (qRT-PCR) were performed to investigate the mechanisms. RES administration decreased arthritis scores and serum levels of antioxidant enzymes, attenuated paw swelling, synovial hyperplasia, inflammatory cell infiltration, and cartilage degradation, as well as inhibited synoviocyte proliferation in synovial tissues. Further investigation indicated that RES inhibited ROS production and FLS proliferation through activating the silent information regulator 1 (SIRT1)/nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway. NF-κB was confirmed to negatively regulate miR-29a-3p and miR-23a-3p expression by directly binding to its promoter. Mechanistic analyses further revealed that Kelch-like erythroid cell-derived protein with CNC homology (ECH)-associated protein 1 (Keap1), a negative regulator of Nrf2, was a downstream target of miR-29a-3p, while miR-23a-3p directly targeted cullin3 (cul3), a master regulator of ubiquitination and degradation of Nrf2. Together, the present study provided evidence that RES ameliorated RA through activation of Nrf2-ARE signaling pathway via SIRT1/NF-κB/miR-29a-3p/Keap1 and SIRT1/NF-κB/miR-23a-3p/cul3 signaling pathway.

Induction of Antioxidant Protein HO-1 Through Nrf2-ARE Signaling Due to Pteryxin in Peucedanum Japonicum Thunb in RAW264.7 Macrophage Cells.

This study focused on exploring the nuclear factor-erythroid-2-related factor (Nrf2) active compound to avoid oxidative stress related to various diseases, such as obesity and diabetes mellitus. The activity of the Nrf2-ARE (antioxidant response element) signaling was evaluated by a reporter assay involving over five hundred various edible medicinal herbs, and the highest Nrf2 activity was found in the ethanol extract of Peucedanum japonicum leaves. The active compound in the extract was isolated by high performance liquid chromatography (HPLC), and the chemical structure was identical to pteryxin based on 1H, 13C-NMR spectra and liquid chromatography/time-of-fright mass spectrometer (LC/TOF/MS). From the pteryxin, the transcription factor Nrf2 was accumulated in the nucleus and resulted in the expression of the antioxidant protein, heme oxygenase-1 (HO-1). In addition, the Nrf2 activity involving HO-1 expression due to coumarin derivatives was evaluated together with pteryxin. This suggested that the electrophilicity, due to the α,β-carbonyl and/or substituted acyl groups in the molecule, modulates the cysteine residue in Keap1 via the Michel reaction, at which point the Nrf2 is dissociated from the Keap1. These results suggest that pteryxin will be a useful agent for developing functional foods.

Association between genetic polymorphisms of NRF2, KEAP1, MAFF, MAFK and anti-tuberculosis drug-induced liver injury: a nested case-control study

Reactive metabolites of anti-tuberculosis (anti-TB) drugs can result in excessive reactive oxygen species (ROS), which are responsible for drug-induced liver injury. The nuclear factor erythroid 2-related factor 2 (Nrf2) - antioxidant response elements (ARE) (Nrf2-ARE) signaling pathway plays a crucial role in protecting liver cells from ROS, inducing enzymes such as phase II metabolizing enzymes and antioxidant enzymes. Based on a Chinese anti-TB treatment cohort, a nested case-control study was performed to explore the association between 13 tag single-nucleotide polymorphisms (tagSNPs) in the NRF2, KEAP1, MAFF, MAFK genes in Nrf2-ARE signaling pathway and the risk of anti-TB drug-induced liver injury (ATLI) in 314 cases and 628 controls. Conditional logistic regression models were used to calculate odds ratios (ORs) and 95% confidence intervals (CIs) after adjusting weight and usage of hepatoprotectant. Patients carrying the TC genotype at rs4243387 or haplotype C-C (rs2001350-rs6726395) in NRF2 were at an increased risk of ATLI (adjusted OR = 1.362, 95% CI: 1.017–1.824, P = 0.038; adjusted OR = 2.503, 95% CI: 1.273–4.921, P = 0.008, respectively), whereas patients carrying TC genotype at rs2267373 or haplotype C-G-C (rs2267373-rs4444637-rs4821767) in MAFF were at a reduced risk of ATLI (adjusted OR = 0.712, 95% CI: 0.532–0.953, P = 0.022; adjusted OR = 0.753, 95% CI: 0.587–0.965, P = 0.025, respectively). Subgroup analysis also detected a significant association between multiple tagSNPs (rs4821767 and rs4444637 in MAFF, rs4720833 in MAFK) and specific clinical patterns of liver injury under different genetic models. This study shows that genetic polymorphisms of NRF2, MAFF and MAFK may contribute to the susceptibility to ATLI in the Chinese anti-TB treatment population.

Nrf2-ARE signaling in cellular protection: Mechanism of action and the regulatory mechanisms.

Oxidative stress is the increase in cellular oxidant concentration in comparison to antioxidant titer. Toxic insults and many other diseased conditions are mediated through the formation of such condition. Once the redox equilibrium is disrupted, the cellular antioxidant system functions to bring back the cell to redox homeostasis state. The field players of the cytoprotective machinery are the xenobiotic-metabolizing enzymes that are transcriptionally controlled by upstream regulatory pathways like the Nrf2-ARE pathway and AhR-XRE pathway. The importance of Nrf2 lies in the fact that it is activated by a variety of compounds and has a wide range of inducers including metals, organic toxicants and so forth. The present review article aims to discuss the role of Nrf2 in cellular protection and also intends to illuminate the regulatory mechanisms that control Nrf2 itself. This can add to our knowledge of how the cell reacts and survives against such stressed conditions.

Discovery of Keap1−Nrf2 small−molecule inhibitors from phytochemicals based on molecular docking

Various phytochemicals have been reported to protect against oxidative stress. However, the mechanism underlying has not been systematically evaluated, which limited their application in disease treatment. Nuclear factor erythroid 2−related factor 2 (Nrf2), a central transcription factor in oxidative stress response related to numerous diseases, is activated after dissociating from the cytoskeleton−anchored Kelch−like ECH−associated protein 1 (Keap1). The Keap1–Nrf2 protein–protein interaction has become an important drug target. This study was designed to clarify whether antioxidantive phytochemicals inhibit the Keap1–Nrf2 protein–protein interaction and activate the Nrf2-ARE signaling pathway efficiently. Molecular docking and 3D−QSAR were applied to evaluate the interaction effects between 178 antioxidant phytochemicals and the Nrf2 binding site in Keap1. The Nrf2 activation effect was tested on a H2O2−induced oxidative−injured cell model. Results showed that the 178 phytochemicals could be divided into high−, medium−, and low−total−score groups depending on their binding affinity with Keap1, and the high−total−score group consisted of 24 compounds with abundant oxygen or glycosides. Meanwhile, these compounds could bind with key amino acids in the structure of the Keap1−Nrf2 interface. Compounds from high−total−score group show effective activation effects on Nrf2. In conclusion, phytochemicals showed high binding affinity with Keap1 are promising new Nrf2 activators.

Protective mechanism of nuclear factor E2 related factor 2 signaling pathway on lung ischemia-reperfusion injury

Objective To investigate the protective effect and mechanism of nuclear factor E2 related factor 2 (Nrf2) signaling pathway on lung ischemia-reperfusion injury (IRI) through ischemic postconditioning. Methods Thirty non-specific pathogen (SPF) SD rats were randomly divided into 3 groups (n=10 each group): IRI surgical treatment group, sham operation group and ischemic post-treatment group. Rat model of lung IRI and rat model of ischemic postconditioning were established. The ischemic post-treatment group was modeled for ischemic postconditioning. In the sham operation group, except for the left lung without clamping artery, the rest procedures were the same as in the IRI surgical treatment group. Results The body weight and wet/dry weight ratio (W/D) in the ischemic post-treatment group were significantly lower than those in the IRI surgical treatment group and the sham operation group (P<0.05). The lung weight and W/D level in the IRI surgical treatment group were significantly lower than in the sham operation group (P<0.05). The sham operation group had a thin alveolar wall and clear structure without obvious edema after 105 min of continuous perfusion of the hilar, similar to normal lung tissue structure. In IRI surgical treatment (45 min of ischemia and 60 min of reperfusion), the alveolar space was significantly widened, the pulmonary edema was significantly aggravated, and the pulp in the alveolar cavity was exuded. In the ischemic post-treatment group, the alveolar space became narrower and the edema was relieved. Thee mRNA expression levels of Nrf2, corticoperoxidase 6 (Prx6), heme oxygenase-1 (HO-1), coenzyme Ⅰ/Ⅱ oxidoreductase (NQO1), glutamate caspase and amino acid ligase modified subunit (Gclm) in the ischemic post-treatment group were significantly reduced as compared with those in the IRI surgical treatment group and sham operation group (all P<0.05). Conclusion Nrf2 can regulate oxidative stress injury through Nrf2-ARE signaling in SD rats, and it can resist oxidative stress damage through Nrf2 after ischemic postconditioning. Key words: Nuclear factor E2 related factor 2 signaling pathway; Ischemic postconditioning; Lung ischemia-reperfusion injury; Protective effect

EPO Attenuates Cisplatin-Induced Ototoxicity in HEI-OC1 Auditory Cell Via the Nrf2-ARE Signaling Pathway.

Erythropoietin (EPO) may protect against cisplatin-induced ototoxicity in HEI-OC1 auditory cell line. Cisplatin is a widely used chemotherapeutic agent for the treatment of human solid tumors limited by its high incidence of ototoxicity. Currently, there are no clinical solutions. EPO has been reported to have varieties of neuroprotective effects. However, nothing has yet been reported on its potential to prevent cisplatin ototoxicity in auditory cell lines and possible mechanism. HEI-OC1 cells were incubated with 20 μM of cisplatin for 48 hours, after application of various concentrations of EPO for 24 hours. Cell viability was determined using a Cell Counting Kit-8 (CCK-8) assay. Oxidative stress and apoptosis were assessed by reactive oxygen species (ROS) measurement, Hoechst 33258 staining, and flow cytometry (FC). Western blot (WB) and real-time quantitative PCR were used to detect nuclear factor erythroid 2-related factor 2 (Nrf2), NAD (P)H quinone oxidoreductase 1 (NQO1), heme oxygenase-1 (HO-1), Bcl-2 and Bcl-xl protein and mRNA expression levels. Pretreatment with 40, 8, and 1.6 ng/mL of EPO for 24 hours before application of 20 μM cisplatin increased cell viability in HEI-OC1 cells. Besides, EPO enhanced the expression of Nrf-2, HO-1, and NQO1. Moreover, upregulation of the expression of Bcl-2 and bcl-xl were also observed. Our results suggest that EPO alleviates cisplatin-induced ototoxicity by activating Nrf2-ARE signaling.