Translational control of nrf2 protein in activation of antioxidant response by oxidants

Development of an Oxygen-Insensitive Nrf2 Reporter Reveals Redox Regulation under Physiological Normoxia

Reactive oxygen species, particularly hydrogen peroxide (H2O2), play crucial roles in cellular signaling, with Nrf2 serving as a key transcription factor in maintaining redox homeostasis. However, the precise influence of H2O2 on Nrf2 activity under physiological normoxia remains unclear due to the limitations of oxygen-sensitive imaging methods. To address this, we developed and validated an oxygen-insensitive Nrf2 reporter named pericellular oxygen-insensitive Nrf2 transcriptional performance reporter (POINTER). We employed this reporter in human cerebral microvascular endothelial cells (hCMEC/D3). Using POINTER, we investigated how varying intracellular H2O2 concentrations affect Nrf2 regulation under normoxia (5 kPa O2) compared to hyperoxia (ambient air, 21 kPa O2). We manipulated intracellular H2O2 levels through exogenous application, chemogenetic production using a modified amino acid oxidase, and pharmacological induction with Auranofin. Our findings reveal that Nrf2 transcriptional activity is significantly lower under normoxia than under hyperoxia, supporting previous literature and expectations. Using POINTER, we found that both antioxidant pathway inhibition and sustained H2O2 elevation are essential for modulating Nrf2 activity. These findings provide new insights into the regulation of Nrf2 by H2O2.

DExH-Box Helicase 9 Participates in De Novo Nrf2 Protein Translation Under Oxidative Stress

Nrf2 transcript factor plays an important role in cellular defense against oxidative stress due to its control for expression of antioxidant and detoxification genes. We have found that Nrf2 gene undergoes de novo protein translation when mammalian cells encounter oxidative stress. Here, we report the discovery of DExH-box helicase-9 (DHX9), also known as RNA helicase A, as a binding protein for Nrf2 mRNA at 5'UTR. DHX9 binding to Nrf2 5'UTR increased with increasing doses (50-300 μM) of H2O2 or treatment time (10-120 min). This incease was in parallel with elevation of Nrf2 protein. Inhibiting DHX9 expression with siRNA or its activity with YK-4-279 inhibitor blocked H2O2 from inducing Nrf2 mRNA recruitment to the ribosomes or Nrf2 protein elevation. As a nuclear protein, DHX9 was found to increase its abundance in the cytosol with oxidative stress. An increase of DHX9 was detected in the ribosomes from cells treated with H2O2, most significantly with 100 μM H2O2, and at 60 min. Ribosomal fractionation revealed an increase of DHX9 protein at 43/48S and 80S fractions in H2O2-treated cells. H2O2 treatment caused an RNA-dependent increase of DHX9 interaction with eIF3η. The binding of DHX9 to Nrf2 5'UTR was enhanced by H2O2-treated cells or by deducting the length of Nrf2 5'UTR. RNase digestion enhanced DHX9 association with the ribosomes. Our data have revealed a novel mechanism of de novo Nrf2 protein translation under oxidative stress involving DHX9 binding to Nrf2 5'UTR, perhaps via removal of a negative RNA element, to recruit 43S preinitiation complex for translation initiation.

Benzoic Acid, Enterococcus faecium, and Essential Oil Complexes Improve Ovarian and Intestinal Health via Modulating Gut Microbiota in Laying Hens Challenged with Clostridium perfringens and Coccidia

Intestinal disease is becoming increasingly prevalent in poultry production; however, the effect of BEC in laying hens challenged with C. perfringens and coccidia is limited. This study aimed to investigate the effects of dietary supplementation with BEC on intestinal and ovarian health in laying hens challenged with C. perfringens and coccidia. A total of 80 Lohmann gray hens (35 weeks) were randomly assigned to two dietary groups supplemented with BEC (0 or 1000 mg/kg). Each group contained 40 replicates, with one bird each (one hen per cage). During the sixth week of the trial, half of the laying hens in each group (n = 20) were administered 40 mL C. perfringens (2.5 × 1010 CFU/mL) and 0.15 mL coccidia (55,000 sporangia/mL), while the other half (n = 20) were administered 40 mL phosphate-buffered saline (PBS). The results indicated that those challenged with C. perfringens and coccidia had severely damaged jejunal and ovarian histopathological morphology, increased oxidative damage, decreased cecal acetic acid and butyric acid content (p < 0.05), and resulted in lower gut microbial richness and diversity. The diet of 1000 mg/kg BEC reduced the jejunal and ovarian pathological damage and oxidative damage, increased short-chain fatty acids (SCFAs) content, and enhanced gut microbial richness and diversity (p < 0.05) in laying hens challenged with C. perfringens and coccidia. Furthermore, the positive effects of BEC on intestinal health were associated with changes in gut microbial composition and structure. In summary, dietary supplementation with BEC has the potential to reduce the severity of intestinal and ovarian damage caused by challenges posed by C. perfringens and coccidia through the modulation of gut microbiota.

Unlocking peak performance: The role of Nrf2 in enhancing exercise outcomes and training adaptation in humans

Since the discovery of the nuclear factor erythroid-derived 2-like 2 (Nrf2) transcription factor thirty years ago, it has been shown that it regulates more than 250 genes involved in a multitude of biological processes, including redox balance, mitochondrial biogenesis, metabolism, detoxification, cytoprotection, inflammation, immunity, autophagy, cell differentiation, and xenobiotic metabolism. In skeletal muscle, Nrf2 signalling is primarily activated in response to perturbation of redox balance by reactive oxygen species or electrophiles. Initial investigations into human skeletal muscle Nrf2 responses to exercise, dating back roughly a decade, have consistently indicated that exercise-induced ROS production stimulates Nrf2 signalling. Notably, recent studies employing Nrf2 knockout mice have revealed impaired skeletal muscle contractile function characterised by reduced force output and increased fatigue susceptibility compared to wild-type counterparts. These deficiencies partially stem from diminished basal mitochondrial respiratory capacity and an impaired capacity to upregulate specific mitochondrial proteins in response to training, findings corroborated by inducible muscle-specific Nrf2 knockout models. In humans, baseline Nrf2 expression in skeletal muscle correlates with maximal oxygen uptake and high-intensity exercise performance. This manuscript delves into the mechanisms underpinning Nrf2 signalling in response to acute exercise in human skeletal muscle, highlighting the involvement of ROS, antioxidants and Keap1/Nrf2 signalling in exercise performance. Furthermore, it explores Nrf2's role in mediating adaptations to chronic exercise and its impact on overall exercise performance. Additionally, the influence of diet and certain supplements on basal Nrf2 expression and its role in modulating acute and chronic exercise responses are briefly addressed.

Del Nido cardioplegia or potassium induces Nrf2 and protects cardiomyocytes against oxidative stress

Open heart surgery is often an unavoidable procedure for the treatment of coronary artery disease. The procedure-associated reperfusion injury affects postoperative cardiac performance and long-term outcomes. We addressed here whether cardioplegia essential for cardiopulmonary bypass surgery activates Nrf2, a transcription factor regulating the expression of antioxidant and detoxification genes. With commonly used cardioplegic solutions, high K+, low K+, Del Nido (DN), histidine-tryptophan-ketoglutarate (HTK), and Celsior (CS), we found that DN caused a significant increase of Nrf2 protein in AC16 human cardiomyocytes. Tracing the ingredients in DN led to the discovery of KCl at the concentration of 20-60 mM capable of significant Nrf2 protein induction. The antioxidant response element (ARE) luciferase reporter assays confirmed Nrf2 activation by DN or KCl. Transcriptomic profiling using RNA-seq revealed that oxidation-reduction as a main gene ontology group affected by KCl. KCl indeed elevated the expression of classical Nrf2 downstream targets, including TXNRD1, AKR1C, AKR1B1, SRXN1, and G6PD. DN or KCl-induced Nrf2 elevation is Ca2+ concentration dependent. We found that KCl decreased Nrf2 protein ubiquitination and extended the half-life of Nrf2 from 17.8 to 25.1 mins. Knocking out Keap1 blocked Nrf2 induction by K+. Nrf2 induction by DN or KCl correlates with the protection against reactive oxygen species generation or loss of viability by H2O2 treatment. Our data support that high K+ concentration in DN cardioplegic solution can induce Nrf2 protein and protect cardiomyocytes against oxidative damage.NEW & NOTEWORTHY Open heart surgery is often an unavoidable procedure for the treatment of coronary artery disease. The procedure-associated reperfusion injury affects postoperative cardiac performance and long-term outcomes. We report here that Del Nido cardioplegic solution or potassium is an effective inducer of Nrf2 transcription factor, which controls the antioxidant and detoxification response. This indicates that Del Nido solution is not only essential for open heart surgery but also exhibits cardiac protective activity.

Methylene Blue Induces Antioxidant Defense and Reparation of Mitochondrial DNA in a Nrf2-Dependent Manner during Cisplatin-Induced Renal Toxicity

Cisplatin is a platinum-based cytostatic drug that is widely used for cancer treatment. Mitochondria and mtDNA are important targets for platinum-based cytostatics, which mediates its nephrotoxicity. It is important to develop therapeutic approaches to protect the kidneys from cisplatin during chemotherapy. We showed that the exposure of mitochondria to cisplatin increased the level of lipid peroxidation products in the in vitro experiment. Cisplatin caused strong damage to renal mtDNA, both in the in vivo and in vitro experiments. Cisplatin injections induced oxidative stress by depleting renal antioxidants at the transcriptome level but did not increase the rate of H₂O₂ production in isolated mitochondria. Methylene blue, on the contrary, induced mitochondrial H₂O₂ production. We supposed that methylene blue-induced H₂O₂ production led to activation of the Nrf2/ARE signaling pathway. The consequences of activation of this signaling pathway were manifested in an increase in the expression of some antioxidant genes, which likely caused a decrease in the amount of mtDNA damage. Methylene blue treatment induced an increase in the expression of genes that were involved in the base excision repair (BER) pathway: the main pathway for mtDNA reparation. It is known that the expression of these genes can also be regulated by the Nrf2/ARE signaling pathway. We can assume that the protective effect of methylene blue is related to the activation of Nrf2/ARE signaling pathways, which can activate the expression of genes related to antioxidant defense and mtDNA reparation. Thus, the protection of kidney mitochondria from cisplatin-induced damage using methylene blue can significantly expand its application in medicine.

Stress Activated MAP Kinases and Cyclin-Dependent Kinase 5 Mediate Nuclear Translocation of Nrf2 via Hsp90α-Pin1-Dynein Motor Transport Machinery

Non-lethal low levels of oxidative stress leads to rapid activation of the transcription factor nuclear factor-E2-related factor 2 (Nrf2), which upregulates the expression of genes important for detoxification, glutathione synthesis, and defense against oxidative damage. Stress-activated MAP kinases p38, ERK, and JNK cooperate in the efficient nuclear accumulation of Nrf2 in a cell-type-dependent manner. Activation of p38 induces membrane trafficking of a glutathione sensor neutral sphingomyelinase 2, which generates ceramide upon depletion of cellular glutathione. We previously proposed that caveolin-1 in lipid rafts provides a signaling hub for the phosphorylation of Nrf2 by ceramide-activated PKCζ and casein kinase 2 to stabilize Nrf2 and mask a nuclear export signal. We further propose a mechanism of facilitated Nrf2 nuclear translocation by ERK and JNK. ERK and JNK phosphorylation of Nrf2 induces the association of prolyl cis/trans isomerase Pin1, which specifically recognizes phosphorylated serine or threonine immediately preceding a proline residue. Pin1-induced structural changes allow importin-α5 to associate with Nrf2. Pin1 is a co-chaperone of Hsp90α and mediates the association of the Nrf2-Pin1-Hsp90α complex with the dynein motor complex, which is involved in transporting the signaling complex to the nucleus along microtubules. In addition to ERK and JNK, cyclin-dependent kinase 5 could phosphorylate Nrf2 and mediate the transport of Nrf2 to the nucleus via the Pin1-Hsp90α system. Some other ERK target proteins, such as pyruvate kinase M2 and hypoxia-inducible transcription factor-1, are also transported to the nucleus via the Pin1-Hsp90α system to modulate gene expression and energy metabolism. Notably, as malignant tumors often express enhanced Pin1-Hsp90α signaling pathways, this provides a potential therapeutic target for tumors.

Fresh Medium or L-Cystine as an Effective Nrf2 Inducer for Cytoprotection in Cell Culture

The Nrf2 gene encodes a transcription factor best known for regulating the expression of antioxidant and detoxification genes. A long list of small molecules has been reported to induce Nrf2 protein via Keap1 oxidation or alkylation. Many of these Nrf2 inducers exhibit off-target or toxic effects due to their nature as electrophiles. In searching for non-toxic Nrf2 inducers, we found that a culture medium change to fresh DMEM is capable of inducing Nrf2 protein in HeLa, HEK293, AC16 and MCF7 cells. Testing the components of DMEM led to the discovery of L-Cystine as an effective Nrf2 inducer. L-Cystine induces a dose-dependent increase of Nrf2 protein, from 0.1 to 1.6 mM. RNA-seq analyses and RT-PCR revealed an induction of multiple Nrf2 downstream genes, including NQO1, HMOX1, GCLC, GCLM, SRXN1, TXNRD1, AKR1C and OSGIN1 by 0.8 mM L-Cystine. The induction of Nrf2 protein was dependent on L-Cystine entering cells via the cystine/glutamate antiporter and the presence of Keap1. The half-life of Nrf2 protein increased from 19.4 min to 30.9 min with 0.8 mM L-Cystine treatment. L-Cystine was capable of eliciting cytoprotection by reducing ROS generation and protecting against oxidant- or doxorubicin-induced apoptosis. As an amino acid derivative, L-Cystine is considered a non-toxic Nrf2 inducer that exhibits the potential for protection against oxidative stress and tissue injury.

Does Nrf2 Play a Role of a Master Regulator of Mammalian Aging?

For a long time Nrf2 transcription factor has been attracting attention of researchers investigating phenomenon of aging. Numerous studies have investigated effects of Nrf2 on aging and cell senescence. Nrf2 is often considered as a key player in aging processes, however this needs to be proven. It should be noted that most studies were carried out on invertebrate model organisms, such as nematodes and fruit flies, but not on mammals. This paper briefly presents main mechanisms of mammalian aging and role of inflammation and oxidative stress in this process. The mechanisms of Nrf2 activity regulation, its involvement in aging and development of the senescence-associated secretory phenotype (SASP) are also discussed. Main part of this review is devoted to critical analysis of available experimental data on the role of Nrf2 in mammalian aging.

Mechanisms underlying Nrf2 nuclear translocation by non-lethal levels of hydrogen peroxide: p38 MAPK-dependent neutral sphingomyelinase2 membrane trafficking and ceramide/PKCζ/CK2 signaling

Hydrogen peroxide is an aerobic metabolite playing a central role in redox signaling and oxidative stress. H₂O₂ could activate redox sensitive transcription factors, such as Nrf2, AP-1 and NF-κB by different manners. In some cells, treatment with non-lethal levels of H₂O₂ induces rapid activation of Nrf2, which upregulates expression of a set of genes involved in glutathione (GSH) synthesis and defenses against oxidative damage. It depends on two steps, the rapid translational activation of Nrf2 and facilitation of Nrf2 nuclear translocation. We review the molecular mechanisms by which H₂O₂ induces nuclear translocation of Nrf2 in cultured cells by highlighting the role of neutral sphingomyelinase 2 (nSMase2), a GSH sensor. H₂O₂ enters cells through aquaporin channels in the plasma membrane and is rapidly reduced to H₂O by GSH peroxidases to consume cellular GSH, resulting in nSMase2 activation to generate ceramide. H₂O₂ also activates p38 MAP kinase, which enhances transfer of nSMase2 from perinuclear regions to plasma membrane lipid rafts to accelerate ceramide generation. Low levels of ceramide activate PKCζ, which then activates casein kinase 2 (CK2). These protein kinases are able to phosphorylate Nrf2 to stabilize and activate it. Notably, Nrf2 also binds to caveolin-1 (Cav1), which protects Nrf2 from Keap1-mediated degradation and limits Nrf2 nuclear translocation. We propose that Cav1serves as a signaling hub for the control of H₂O₂-mediated phosphorylation of Nrf2 by kinases, which results in release of Nrf2 from Cav1 to facilitate nuclear translocation. In summary, H₂O₂ induces GSH depletion which is recovered by Nrf2 activation dependent on p38/nSMase2/ceramide signaling.

The Protective Effect of α-Lipoic Acid against Gold Nanoparticles (AuNPs)-Mediated Liver Damage Is Associated with Upregulating Nrf2 and Suppressing NF-κB

This study examined if regulating the keap-1? Nrf2 antioxidant pathway mediated gold nanoparticles (AuNPs) induced liver damage, and examined the protective effect of co-supplement of α-lipoic acid (α-LA). Rats were separated into 4 groups (n = 8/each) as control, α-LA (200 mg/kg), AuNPs (5 µg/2.85 × 10¹¹), and AuNPs (5 µg/2.85 × 10¹¹) + α-LA (200 mg/kg). After 7 days, AuNPs induced severe degeneration in the livers of rats with the appearance of some fatty changes. In addition, it increased serum levels of alanine aminotransferase (ALT) and gamma-glutamyl transferase (ɣ-GTT), and aspartate aminotransferase (AST), as well as liver levels of malondialdehyde (MDA). Concomitantly, AuNPs significantly depleted hepatic levels of total glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT) but increased hepatic levels of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). It also reduced mRNA levels of B-cell lymphoma 2 (Bcl2) and heme oxygenase-1 (HO-1) but significantly increased those of Bax and cleaved caspase-3, as well as the ratio of Bax/Bcl2. In addition, AuNPs enhanced the total and nuclear levels of NF-κB p65 but reduced the mRNA and total and nuclear protein levels of Nrf2. Of note, AuNPs did not affect the mRNA levels of keap-1. All these events were reversed by α-LA in the AuNPs-treated rats. In conclusion, α-LA attenuated AuNPs-mediated liver damage in rats by suppressing oxidative stress and inflammation, effects that are associated with upregulation/activation of Nrf2.

The Role of Concomitant Nrf2 Targeting and Stem Cell Therapy in Cerebrovascular Disease

Despite the reality that a death from cerebrovascular accident occurs every 3.5 min in the United States, there are few therapeutic options which are typically limited to a narrow window of opportunity in time for damage mitigation and recovery. Novel therapies have targeted pathological processes secondary to the initial insult, such as oxidative damage and peripheral inflammation. One of the greatest challenges to therapy is the frequently permanent damage within the CNS, attributed to a lack of sufficient neurogenesis. Thus, recent use of cell-based therapies for stroke have shown promising results. Unfortunately, stroke-induced inflammatory and oxidative damage limit the therapeutic potential of these stem cells. Nuclear factor erythroid 2-related factor 2 (Nrf2) has been implicated in endogenous antioxidant and anti-inflammatory activity, thus presenting an attractive target for novel therapeutics to enhance stem cell therapy and promote neurogenesis. This review assesses the current literature on the concomitant use of stem cell therapy and Nrf2 targeting via pharmaceutical and natural agents, highlighting the need to elucidate both upstream and downstream pathways in optimizing Nrf2 treatments in the setting of cerebrovascular disease.

Signal amplification in the KEAP1-NRF2-ARE antioxidant response pathway

The KEAP1-NRF2-ARE signaling pathway plays a central role in mediating the adaptive cellular stress response to oxidative and electrophilic chemicals. This canonical pathway has been extensively studied and reviewed in the past two decades, but rarely was it looked at from a quantitative signaling perspective. Signal amplification, i.e., ultrasensitivity, is crucially important for robust induction of antioxidant genes to appropriate levels that can adequately counteract the stresses. In this review article, we examined a number of well-known molecular events in the KEAP1-NRF2-ARE pathway from a quantitative perspective with a focus on how signal amplification can be achieved. We illustrated, by using a series of mathematical models, that redox-regulated protein sequestration, stabilization, translation, nuclear trafficking, DNA promoter binding, and transcriptional induction - which are embedded in the molecular network comprising KEAP1, NRF2, sMaf, p62, and BACH1 - may generate highly ultrasensitive NRF2 activation and antioxidant gene induction. The emergence and degree of ultrasensitivity depend on the strengths of protein-protein and protein-DNA interaction and protein abundances. A unique, quantitative understanding of signal amplification in the KEAP1-NRF2-ARE pathway will help to identify sensitive targets for the prevention and therapeutics of oxidative stress-related diseases and develop quantitative adverse outcome pathway models to facilitate the health risk assessment of oxidative chemicals.

Comparative subcellular localization of NRF2 and KEAP1 during the hepatocellular carcinoma development in vivo

The activation of Nuclear Factor, Erythroid 2 Like 2 - Kelch Like ECH Associated Protein 1 (NRF2-KEAP1) signaling pathway plays a critical dual role by either protecting or promoting the carcinogenesis process. However, its activation or nuclear translocation during hepatocellular carcinoma (HCC) progression has not been addressed yet. This study characterizes the subcellular localization of both NRF2 and KEAP1 during diethylnitrosamine-induced hepatocarcinogenesis in the rat. NRF2-KEAP1 pathway was continuously activated along with the increased expression of its target genes, namely Nqo1, Hmox1, Gclc, and Ptgr1. Similarly, the nuclear translocation of NRF2, MAF, and KEAP1 increased in HCC cells from weeks 12 to 22 during HCC progression. Likewise, colocalization of NRF2 with KEAP1 was higher in the cell nuclei of HCC neoplastic nodules than in surrounding cells. Moreover, immunofluorescence analyses revealed that the interaction of KEAP1 with filamentous Actin was disrupted in HCC cells. This disruption may be contributing to the release and nuclear translocation of NRF2 since the cortical actin cytoskeleton serves as anchoring of KEAP1. In conclusion, this evidence indicates that NRF2 is progressively activated and promotes the progression of experimental HCC.

Protective Effects of N-Acetylcysteine on Lipopolysaccharide-Induced Respiratory Inflammation and Oxidative Stress

As the leading cause of bovine respiratory disease (BRD), bacterial pneumonia can result in tremendous losses in the herd farming industry worldwide. N-acetylcysteine (NAC), an acetylated precursor of the amino acid L-cysteine, has been reported to have anti-inflammatory and antioxidant properties. To explore the protective effect and underlying mechanisms of NAC in ALI, we investigated its role in lipopolysaccharide (LPS)-induced bovine embryo tracheal cells (EBTr) and mouse lung injury models. We found that NAC pretreatment attenuated LPS-induced inflammation in EBTr and mouse models. Moreover, LPS suppressed the expression of oxidative-related factors in EBTr and promoted gene expression and the secretion of inflammatory cytokines. Conversely, the pretreatment of NAC alleviated the secretion of inflammatory cytokines and decreased their mRNA levels, maintaining stable levels of antioxidative gene expression. In vivo, NAC helped LPS-induced inflammatory responses and lung injury in ALI mice. The relative protein concentration, total cells, and percentage of neutrophils in BALF; the level of secretion of IL-6, IL-8, TNF-α, and IL-1β; MPO activity; lung injury score; and the expression level of inflammatory-related genes were decreased significantly in the NAC group compared with the LPS group. NAC also ameliorated LPS-induced mRNA level changes in antioxidative genes. In conclusion, our findings suggest that NAC affects the inflammatory and oxidative response, alleviating LPS-induced EBTr inflammation and mouse lung injury, which offers a natural therapeutic strategy for BRD.

Metabolomics of oxidative stress: Nrf2 independent depletion of NAD or increases of sugar alcohols

Nrf2 encodes a transcription factor best known for regulating the expression of antioxidant and detoxification genes. Recent evidence suggested that Nrf2 mediates metabolic reprogramming in cancer cells. However, the role of Nrf2 in the biochemical metabolism of cardiac cells has not been studied. Using LC-MS/MS-based metabolomics, we addressed whether knocking out the Nrf2 gene in AC16 human cardiomyocytes affects metabolic reprogramming by oxidative stress. Profiling the basal level metabolites showed an elevated pentose phosphate pathway and increased levels of sugar alcohols, sorbitol, L-arabitol, xylitol and xylonic acid, in Nrf2 KO cells. With sublethal levels of oxidative stress, depletion of NAD, an increase of GDP and elevation of sugar alcohols, sorbitol and dulcitol, were detected in parent wild type (WT) cells. Knocking out Nrf2 did not affect these changes. Biochemical assays confirmed depletion of NAD in WT and Nrf2 KO cells due to H₂O₂ treatment. These data support that although Nrf2 deficiency caused baseline activation of the pentose phosphate pathway and sugar alcohol synthesis, a brief exposure to none-lethal doses of H₂O₂ caused NAD depletion in an Nrf2 independent manner. Loss of NAD may contribute to oxidative stress associated cell degeneration as observed with aging, diabetes and heart failure.

A Common Feature of Pesticides: Oxidative Stress-The Role of Oxidative Stress in Pesticide-Induced Toxicity

Pesticides are important chemicals or biological agents that deter or kill pests. The use of pesticides has continued to increase as it is still considered the most effective method to reduce pests and increase crop growth. However, pesticides have other consequences, including potential toxicity to humans and wildlife. Pesticides have been associated with increased risk of cardiovascular disease, cancer, and birth defects. Labels on pesticides also suggest limiting exposure to these hazardous chemicals. Based on experimental evidence, various types of pesticides all seem to have a common effect, the induction of oxidative stress in different cell types and animal models. Pesticide-induced oxidative stress is caused by both reactive oxygen species (ROS) and reactive nitrogen species (RNS), which are associated with several diseases including cancer, inflammation, and cardiovascular and neurodegenerative diseases. ROS and RNS can activate at least five independent signaling pathways including mitochondrial-induced apoptosis. Limited in vitro studies also suggest that exogenous antioxidants can reduce or prevent the deleterious effects of pesticides.

Carotenoids and Carcinogenesis: Exploring the Antioxidant and Cell Signaling Roles of Carotenoids in the Prevention of Cancer

Carotenoids are lipid soluble pigments found in various fruits and vegetables and are naturally produced in photoautotrophic plants. Various studies have investigated the properties of carotenoids to determine how they are able to mitigate numerous diseases, including cancer. Carotenoids present in human serum, including β-carotene, α-carotene, lycopene, β-cryptoxanthin, zeaxanthin, and lutein have demonstrated the ability to act as anticarcinogenic agents. Prevention of disease is often described to be more effective than treatment; as cancer impacts millions of lives globally, the role of carotenoids in the prevention of oncogenesis for numerous types of cancers have been extensively researched. This review provides an in-depth analysis of the structure and properties of carotenoids, as well as the identified and potential mechanisms by which carotenoids can act as a chemopreventative agent.

The Nrf2 Pathway in Ischemic Stroke: A Review

Ischemic stroke, characterized by the sudden loss of blood flow in specific area(s) of the brain, is the leading cause of permanent disability and is among the leading causes of death worldwide. The only approved pharmacological treatment for acute ischemic stroke (intravenous thrombolysis with recombinant tissue plasminogen activator) has significant clinical limitations and does not consider the complex set of events taking place after the onset of ischemic stroke (ischemic cascade), which is characterized by significant pro-oxidative events. The transcription factor Nuclear factor erythroid 2-related factor 2 (Nrf2), which regulates the expression of a great number of antioxidant and/or defense proteins, has been pointed as a potential pharmacological target involved in the mitigation of deleterious oxidative events taking place at the ischemic cascade. This review summarizes studies concerning the protective role of Nrf2 in experimental models of ischemic stroke, emphasizing molecular events resulting from ischemic stroke that are, in parallel, modulated by Nrf2. Considering the acute nature of ischemic stroke, we discuss the challenges in using a putative pharmacological strategy (Nrf2 activator) that relies upon transcription, translation and metabolically active cells in treating ischemic stroke patients.

Nrf2 for cardiac protection: pharmacological options against oxidative stress

Myocardial ischemia or reperfusion increases the generation of reactive oxygen species (ROS) from damaged mitochondria, NADPH oxidases, xanthine oxidase, and inflammation. ROS can be removed by eight endogenous antioxidant and redox systems, many components of which are expressed under the influence of the activated Nrf2 transcription factor. Transcriptomic profiling, sequencing of Nrf2-bound DNA, and Nrf2 gene knockout studies have revealed the power of Nrf2 beyond the antioxidant and detoxification response, from tissue recovery, repair, and remodeling, mitochondrial turnover, and metabolic reprogramming to the suppression of proinflammatory cytokines. Multifaceted regulatory mechanisms for Nrf2 protein levels or activity have been mapped to its functional domains, Nrf2-ECH homology (Neh)1-7. Oxidative stress activates Nrf2 via nuclear translocation, de novo protein translation, and increased protein stability due to removal of the Kelch-like ECH-associated protein 1 (Keap1) checkpoint, or the inactivation of β-transducin repeat-containing protein (β-TrCP), or Hmg-CoA reductase degradation protein 1 (Hrd1). The promise of small-molecule Nrf2 inducers from natural products or derivatives is discussed here. Experimental evidence is presented to support Nrf2 as a lead target for drug development to further improve the treatment outcome for myocardial infarction (MI).

Far Upstream Binding Protein 1 (FUBP1) participates in translational regulation of Nrf2 protein under oxidative stress

Oxidative stress is ubiquitously involved in disease etiology or progression. While the damaging effects have been well characterized, how cells deal with oxidative stress for prevention or removal of damage remains to be fully elucidated. Works from our laboratory have revealed de novo Nrf2 protein translation when cells are encountering low to mild levels of oxidative stress. Nrf2 encodes a transcription factor controlling a myriad of genes important for antioxidation, detoxification, wound repair and tissue remodeling. Here we report a role of FUBP1 in regulating de novo Nrf2 protein translation. An increase of FUBP1 binding to Nrf2 5′UTR due to H₂O₂ treatment has been found by LC-MS/MS, Far Western blot and ribonucleoprotein immunoprecipitation assays. Blocking FUBP1 expression using siRNA abolished H₂O₂ from inducing Nrf2 protein elevation or Nrf2 5′UTR activity. While no nuclear to cytoplasmic translocation was detected, cytosolic redistribution to the ribosomal fractions was observed due to oxidant treatment. The presence of FUBP1 in 40/43S ribosomal fractions confirm its involvement in translation initiation of Nrf2 protein. When tested by co-immunoprecipitation with eIF4E, eIF2a, eIF3η and eIF1, only eIF3η was found to gain physical interaction with FUBP1 due to H₂O₂ treatment. Our data support a role of FUBP1 for promoting the attachment of 40S ribosomal subunit to Nrf2 mRNA and formation of 43S pre-initiation complex for translation initiation of Nrf2 protein under oxidative stress.

The immunoreaction and antioxidant capacity of juvenile blunt snout bream (Megalobrama amblycephala) involves the PI3K/Akt/Nrf2 and NF-κB signal pathways in response to dietary methionine levels

A 75-day rearing trail was designed to evaluate the immunoreaction and antioxidant capacity of juvenile blunt snout bream in response to dietary methionine levels. Three practical diets were extruded to feed juveniles with graded methionine levels (0.40%, 0.84% and 1.28% dry matter). The data indicated that the plasma concentrations of immunoglobulin M (IgM), complement component 3 (C3) and glutathione (GSH) in the 0.84% methionine diet were markedly upper than those in the 0.40% group (P < 0.05). The activities of plasma antioxidant parameters involving catalase (CAT), total superoxide dismutase (T-SOD), total antioxidant capacity (T-AOC) and glutathione peroxidase (GPx) were significantly increased by the 0.84% diet compared with the 0.40% diet, whereas plasma alanine aminotransferase (ALT) and malondialdehyde (MDA) levels were significantly induced by 0.40% methionine (P < 0.05). Compared with the 0.40% group, 0.84% dietary methionine dramatically upregulated the mRNA expression levels of protein kinase B (Akt), phosphoinositide 3-kinase (PI3K) and nuclear factor erythroid 2-related factor 2 (Nrf2) pathway related genes including CAT, manganese superoxide dismutase (Mn-SOD), heme oxygenase 1 (HO-1) and glutathione peroxidase-1 (GPx-1) in the kidney and liver, and downregulated Kelch-like ECH-associated protein 1 (Keap1) mRNA levels (P < 0.05). Compared with the 0.40% group, the 0.84% dietary methionine strikingly suppressed the mRNA levels of renal and hepatic nuclear factor-kappa B (NF-κB) and pro-inflammatory cytokines (interleukin 1β (IL-1β), tumor necrosis factor-α (TNF-α), interleukin 6 (IL-6)), however, improved the mRNA expression levels of anti-inflammatory cytokines involved renal and hepatic transforming growth factor-β (TGF-β) and hepatic interleukin 10 (IL-10) (P < 0.05). Renal IL-10 and interleukin 8 (IL-8) mRNA expression levels were not markedly influenced by experimental diets (P > 0.05). Dietary methionine (0.84%) significantly upregulated renal and hepatic heat stress protein 70 (Hsp70), renal B-cell lymphoma-2 (Bcl-2) gene expression levels compared with the 0.40% diet (P < 0.05). In a word, the data represented that 0.84% dietary methionine could enhance the immune and antioxidant capacity of this fish species by inducing PI3K/Akt/Nrf2 pathway and inhibiting NF-κB pathway.

Astaxanthin Suppresses PM2.5-Induced Neuroinflammation by Regulating Akt Phosphorylation in BV-2 Microglial Cells

Air pollution has become one of the most serious issues for human health and has been shown to be particularly concerning for neural and cognitive health. Recent studies suggest that fine particulate matter of less than 2.5 (PM2.5), common in air pollution, can reach the brain, potentially resulting in the development and acceleration of various neurological disorders including Alzheimer’s disease, Parkinson’s disease, and other forms of dementia, but the underlying pathological mechanisms are not clear. Astaxanthin is a red-colored phytonutrient carotenoid that has been known for anti-inflammatory and neuroprotective effects. In this study, we demonstrated that exposure to PM2.5 increases the neuroinflammation, the expression of proinflammatory M1, and disease-associated microglia (DAM) signature markers in microglial cells, and that treatment with astaxanthin can prevent the neurotoxic effects of this exposure through anti-inflammatory properties. Diesel particulate matter (Sigma-Aldrich) was used as a fine particulate matter 2.5 in the present study. Cultured rat glial cells and BV-2 microglial cells were treated with various concentrations of PM2.5, and then the expression of various inflammatory mediators and signaling pathways were measured using qRT-PCR and Western blot. Astaxanthin was then added and assayed as above to evaluate its effects on microglial changes, inflammation, and toxicity induced by PM2.5. PM2.5 increased the production of nitric oxide and reactive oxygen species and upregulated the transcription of various proinflammatory markers including Interleukin-1β (IL-1β), Interleukin-6 (IL-6), Tumor necrosis factor α (TNFα), inducible nitric oxide synthase (iNOS), triggering receptor expressed on myeloid cells 2 (TREM2), Toll-like receptor 2/4 (TLR2/4), and cyclooxygenase-2 (COX-2) in BV-2 microglial cells. However, the mRNA expression of IL-10 and arginase-1 decreased following PM2.5 treatment. PM2.5 treatment increased c-Jun N-terminal kinases (JNK) phosphorylation and decreased Akt phosphorylation. Astaxanthin attenuated these PM2.5-induced responses, reducing transcription of the proinflammatory markers iNOS and heme oxygenase-1 (HO-1), which prevented neuronal cell death. Our results indicate that PM2.5 exposure reformulates microglia via proinflammatory M1 and DAM phenotype, leading to neurotoxicity, and the fact that astaxanthin treatment can prevent neurotoxicity by inhibiting transition to the proinflammatory M1 and DAM phenotypes. These results demonstrate that PM2.5 exposure can induce brain damage through the change of proinflammatory M1 and DAM signatures in the microglial cells, as well as the fact that astaxanthin can have a potential beneficial effect on PM2.5 exposure of the brain.

Illicium verum extracts and probiotics with added glucose oxidase promote antioxidant capacity through upregulating hepatic and jejunal Nrf2/Keap1 of weaned piglets

Accumulating evidences indicate that plant extracts and probiotics are effective antioxidant substitutes which play important roles in animal production. However, the comparative study of the mechanism underlying the antioxidant property of Illicium verum extracts (IVE) and probiotics with added glucose oxidase (PGO) on piglets remains to be explored. This study evaluated the difference and the interaction effect of IVE and PGO on serum, liver, and jejunum antioxidant capacity of weaned piglets. A total of 32 weaned piglets (Duroc × Landrace × Yorkshire) at the age of 28 d with an average body weight of 14.96 ± 0.32 kg were randomly divided into four treatments with eight replicates per treatment in a 2 × 2 factorial arrangement. Treatments included basal diet (IVE-PGO-), basal diet + 1,000 mg/kg PGO (IVE-PGO+), basal diet + 500 mg/kg IVE (IVE+PGO-), and basal diet + 500 mg/kg IVE + 1,000 mg/kg PGO (IVE+PGO+). All the piglets were housed individually for the 42-d trial period after 7-d adaptation. The piglets were euthanized at the end of the experiment and the liver and jejunum samples were taken and subjected to immunohistochemistry, Western blotting, as well as antioxidant and qRT-PCR analysis. Significant interactions were observed between IVE and PGO for total superoxide dismutase (T-SOD) and glutathione peroxidase (GSH-Px) in serum (42 d), liver, and jejunum; malondialdehyde (MDA) in serum (21 d); and mRNA and protein expression of kelch sample related protein-1 (Keap1) and nuclear factor erythroid-2 related factor (Nrf2)/Keap1 in the liver and jejunum (P < 0.05). Both IVE and PGO improved (P < 0.05) T-SOD and GSH-Px in the serum (42 d), liver, and jejunum, and the mRNA and protein expression of Nrf2 and Nrf2/Keap1 in the liver and jejunum, but decreased (P < 0.05) MDA in the serum (21 d) and the mRNA and protein expression of Keap1 in the liver and jejunum. Immunohistochemical results confirmed that IVE and PGO enhanced the positive reactions of Nrf2 but weakened Keap1 in both the liver and jejunum. In conclusion, the results confirmed that IVE (500 mg/kg) and PGO (1,000 mg/kg) can improve the antioxidant capacity of weaned piglets and that the interaction effect between IVE and PGO is significant. At the same time, the fact that IVE and PGO activate the Nrf2/Keap1 in the liver and jejunum signaling pathway suggests that they play an important role in the ameliorative antioxidant capacity of weaned piglets. Therefore, the combination of IVE and PGO could be recommended as a new potential alternative to antibiotics in piglets' diets.

Progressive Rotavirus Infection Downregulates Redox-Sensitive Transcription Factor Nrf2 and Nrf2-Driven Transcription Units

Eukaryotic cells adopt highly tuned stress response physiology under threats of exogenous stressors including viruses to maintain cellular homeostasis. Not surprisingly, avoidance of cellular stress response pathways is an essential facet of virus-induced obligatory host reprogramming to invoke a cellular environment conducive to viral perpetuation. Adaptive cellular responses to oxidative and electrophilic stress are usually taken care of by an antioxidant defense system, core to which lies the redox-responsive transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) and Nrf2-driven transcriptional cascade. Deregulation of host redox balance and redox stress-sensitive Nrf2 antioxidant defense have been reported for many viruses. In the current study, we aimed to study the modulation of the Nrf2-based host cellular redox defense system in response to Rotavirus (RV) infection in vitro. Interestingly, we found that Nrf2 protein levels decline sharply with progression of RV infection beyond an initial upsurge. Moreover, Nrf2 decrease as a whole was found to be accompanied by active nuclear vacuity of Nrf2, resulting in lowered expression of stress-responsive Nrf2 target genes heme oxygenase-1 (HO-1), NAD(P)H quinone dehydrogenase 1, and superoxide dismutase 1 both in the presence and absence of Nrf2-driven transcriptional inducers. Initial induction of Nrf2 concurred with RV-induced early burst of oxidative stress and therefore was sensitive to treatments with antioxidants. Reduction of Nrf2 levels beyond initial hours, however, was found to be independent of the cellular redox status. Furthermore, increasing the half-life of Nrf2 through inhibition of the Kelch-like erythroid cell-derived protein with CNC homology- (ECH-) associated protein 1/Cullin3-RING Box1-based canonical Nrf2 turnover pathway could not restore Nrf2 levels post RV-SA11 infection. Depletion of the Nrf2/HO-1 axis was subsequently found to be sensitive to proteasome inhibition with concurrent observation of increased K48-linked ubiquitination associated with Nrf2. Together, the present study describes robust downregulation of Nrf2-dependent cellular redox defense beyond initial hours of RV infection, justifying our previous observation of potent antirotaviral implications of Nrf2 agonists.

Potential implications of hydrogen peroxide in the pathogenesis and therapeutic strategies of gliomas

Glioma is the most common type of primary brain tumor, and it has a high mortality rate. Currently, there are only a few therapeutic approaches for gliomas, and their effects are unsatisfactory. Therefore, uncovering the pathogenesis and exploring more therapeutic strategies for the treatment of gliomas are urgently needed to overcome the ongoing challenges. Cellular redox imbalance has been shown to be associated with the initiation and progression of gliomas. Among reactive oxygen species (ROS), hydrogen peroxide (H₂O₂) is considered the most suitable for redox signaling and is a potential candidate as a key molecule that determines the fate of cancer cells. In this review, we discuss the potential cellular and molecular roles of H₂O₂ in gliomagenesis and explore the potential implications of H₂O₂ in radiotherapy and chemotherapy and in the ongoing challenges of current glioma treatment. Moreover, we evaluate H₂O₂ as a potential redox sensor and potential driver molecule of nanocatalytic therapeutic strategies for glioma treatment.

Sulodexide up-regulates glutathione S-transferase P1 by enhancing Nrf2 expression and translocation in human umbilical vein endothelial cells injured by oxygen glucose deprivation

INTRODUCTION

Sulodexide (SDX) is used for the treatment of many vascular disorders due to its anticoagulant, anti-inflammatory and anti-atherosclerotic properties. However, the detailed molecular mechanism of its endothelioprotective action is still not completely understood. There is increasing evidence suggesting that antioxidant enzymes play an important role in anti-ischemic properties of SDX. We postulate that up-regulation of glutathione-S-transferase P1 (GSTP1) mediated by the transcription factor Nrf2 could be associated with the antioxidant effect of SDX on vascular endothelial cells.

MATERIAL AND METHODS

In the present study, we investigated whether SDX affects GSTP1 and Nrf2 in oxygen glucose deprivation (OGD) treated human umbilical vein endothelial cells (HUVECs). The cells treated with/without SDX (0.5 LRU/ml) were subjected to OGD for 1-6 h. To study the influence of SDX on the Nrf2 nucleus accumulation, the cells were incubated with 0.5 LRU/ml SDX in OGD for 1 h.

RESULTS

We found that after short-term OGD (1-3 h), the drug increased the expression of both GSTP1 and Nrf2 mRNA/protein in HUVECs (p < 0.05), as determined by real-time PCR and enzyme-linked immunosorbent assay (ELISA). SDX treatment also enhanced the nuclear accumulation of Nrf2 in HUVECs after 1 h of OGD (p < 0.05).

CONCLUSIONS

SDX induces a rapid onset of the antioxidant response by up-regulating the expression of GSTP1 and Nrf2 in endothelial cells subjected to in vitro simulated ischemia.

Peroxisomal Hydrogen Peroxide Metabolism and Signaling in Health and Disease

Hydrogen peroxide (H₂O₂), a non-radical reactive oxygen species generated during many (patho)physiological conditions, is currently universally recognized as an important mediator of redox-regulated processes. Depending on its spatiotemporal accumulation profile, this molecule may act as a signaling messenger or cause oxidative damage. The focus of this review is to comprehensively evaluate the evidence that peroxisomes, organelles best known for their role in cellular lipid metabolism, also serve as hubs in the H₂O₂ signaling network. We first briefly introduce the basic concepts of how H₂O₂ can drive cellular signaling events. Next, we outline the peroxisomal enzyme systems involved in H₂O₂ metabolism in mammals and reflect on how this oxidant can permeate across the organellar membrane. In addition, we provide an up-to-date overview of molecular targets and biological processes that can be affected by changes in peroxisomal H₂O₂ metabolism. Where possible, emphasis is placed on the molecular mechanisms and factors involved. From the data presented, it is clear that there are still numerous gaps in our knowledge. Therefore, gaining more insight into how peroxisomes are integrated in the cellular H₂O₂ signaling network is of key importance to unravel the precise role of peroxisomal H₂O₂ production and scavenging in normal and pathological conditions.

Polymorphism in the Promoter Region of NFE2L2 Gene Is a Genetic Marker of Susceptibility to Cirrhosis Associated with Alcohol Abuse

Alcoholic liver disease (ALD) is a highly prevalent spectrum of pathologies caused by alcohol overconsumption. Morbidity and mortality related to ALD are increasing worldwide, thereby demanding strategies for early diagnosis and detection of ALD predisposition. A potential candidate as a marker for ALD susceptibility is the transcription factor nuclear factor erythroid-related factor 2 (Nrf2), codified by the nuclear factor erythroid 2-related factor 2 gene (NFE2L2). Nrf2 regulates expression of proteins that protect against oxidative stress and inflammation caused by alcohol overconsumption. Here, we assessed genetic variants of NFE2L2 for association with ALD. Specimens from patients diagnosed with cirrhosis caused by ALD were genotyped for three NFE2L2 single nucleotide polymorphisms (SNP) (SNPs: rs35652124, rs4893819, and rs6721961). Hematoxylin & eosin and immunohistochemistry were performed to determine the inflammatory score and Nrf2 expression, respectively. SNPs rs4893819 and rs6721961 were not specifically associated with ALD, but analysis of SNP rs35652124 suggested that this polymorphism predisposes to ALD. Furthermore, SNP rs35652124 was associated with a lower level of Nrf2 expression. Moreover, liver samples from ALD patients with this polymorphism displayed more severe inflammatory activity. Together, these findings provide evidence that the SNP rs35652124 variation in the Nrf2-encoding gene NFE2L2 is a potential genetic marker for susceptibility to ALD.

HACE1, an E3 Ubiquitin Protein Ligase, Mitigates Kaposi's Sarcoma-Associated Herpesvirus Infection-Induced Oxidative Stress by Promoting Nrf2 Activity

Kaposi's sarcoma-associated herpesvirus (KSHV)-induced activation of nuclear factor erythroid 2-related factor 2 (Nrf2) is essential for both the expression of viral genes (latency) and modulation of the host antioxidant machinery. Reactive oxygen species (ROS) are also regulated by the ubiquitously expressed HACE1 protein (HECT domain and ankyrin repeat containing E3 ubiquitin protein ligase 1), which targets the Rac1 protein for proteasomal degradation, and this blocks the generation of ROS by Rac1-dependent NADPH oxidases. In this study, we examined the role of HACE1 in KSHV infection. Elevated levels of HACE1 expression were observed in de novo KSHV-infected endothelial cells, KSHV latently infected TIVE-LTC and PEL cells, and Kaposi's sarcoma skin lesion cells. The increased HACE1 expression in the infected cells was mediated by KSHV latent protein kaposin A. HACE1 knockdown resulted in high Rac1 and Nox 1 (NADPH oxidase 1) activity, increased ROS (oxidative stress), increased cell death, and decreased KSHV gene expression. Loss of HACE1 impaired KSHV infection-induced phosphoinositide 3-kinase (PI3-K), protein kinase C-ζ (PKC-ζ), extracellular signal-regulated kinase 1/2 (ERK1/2), NF-κB, and Nrf2 activation and nuclear translocation of Nrf2, and it reduced the expression of Nrf2 target genes responsible for balancing the oxidative stress. In the absence of HACE1, glutamine uptake increased in the cells to cope with the KSHV-induced oxidative stress. These findings reveal for the first time that HACE1 plays roles during viral infection-induced oxidative stress and demonstrate that HACE1 facilitates resistance to KSHV infection-induced oxidative stress by promoting Nrf2 activity. Our studies suggest that HACE1 could be a potential target to induce cell death in KSHV-infected cells and to manage KSHV infections.IMPORTANCE ROS play important roles in several cellular processes, and increased ROS cause several adverse effects. KSHV infection of endothelial cells induces ROS, which facilitate virus entry by amplifying the infection-induced host cell signaling cascade, which, in turn, induces the nuclear translocation of phospho-Nrf2 protein to regulate the expression of antioxidative genes and viral genes. The present study demonstrates that KSHV infection induces the E3 ligase HACE1 protein to regulate KSHV-induced oxidative stress by promoting the activation of Nrf2 and nuclear translocation. Absence of HACE1 results in increased ROS and cellular death and reduced nuclear Nrf2, antioxidant, and viral gene expression. Together, these studies suggest that HACE1 can be a potential target to induce cell death in KSHV-infected cells.

Vitamin D3 contributes to enhanced osteogenic differentiation of MSCs under oxidative stress condition via activating the endogenous antioxidant system

The anti-oxidative effects of vitamin D3 (Vd3) on mesenchymal stem cells (MSCs) have not been studied before. The present study suggested that Vd3 could not only promote the osteogenic differentiation of MSCs under normal condition but also partly protect it from oxidative stress damage by activating the endogenous antioxidant system.

INTRODUCTION

Evolving evidence proved that oxidative stress caused by reactive oxygen species (ROS) overproduction might lead to bone loss. Vd3, a commonly used osteogenic induction drug, was proved to exhibit potent anti-oxidative effects on other cell types. The present study aims to investigate the protective effects of Vd3 on oxidative stress-induced dysfunctions of MSCs, as well as its underlying mechanisms.

METHODS

The H₂O₂ was used as exogenous reactive oxygen species (ROS). The influence of ROS and anti-oxidative protection of Vd3 on MSCs were analyzed too. Multi-techniques were used to assess the beneficial effects of Vd3 on MSCs under oxidative stress condition.

RESULTS

The results demonstrated that Vd3 could significantly attenuate the H₂O₂-induced cell injury of MSCs via Sirt1/FoxO1 signaling pathway, and reduced the H₂O₂ exposure-induced intracellular oxidative stress status of MSCs. What's more, the H₂O₂ exposure resulted in the decreased osteogenic differentiation of MSCs, as evidenced by decreased alkaline phosphatase activity, calcium deposition level, and osteogenic differentiation gene mRNA levels, but the injury was restored via Vd3 administration.

CONCLUSIONS

The results suggested that Vd3 could not only promote the osteogenic differentiation of osteoblastic cells under normal condition but also partly protect the cell from oxidative stress damage by activating endogenous antioxidant system. The study shed light on the new roles of Vd3 in bone modeling and remodeling regulation.

Pre and post treatment with curcumin and resveratrol protects astrocytes after oxidative stress

The two most studied polyphenolic compounds, curcumin (Cur) and resveratrol (Res), have been reported to protect oxidative damage of astrocytes. The present study is designed to examine the comparative anti-oxidative effect of Cur and Res on astrocytes by studying their potential to protect H₂O₂ induced oxidative stress at 4 h and 24 h time exposure. The effect of Cur and Res on cell viability, ROS production, inflammation and astrogliosis was compared. The effect of these two on Nrf2 expression and its translocation to nuclear compartment was investigated. The results showed that both Cur and Res significantly increase astrocytes survival after oxidative stress at both time points, however, Res demonstrated better effect on cell viability than the Cur. Res, showing significant inhibition of ROS production at both time points. Cur displayed significant inhibition of ROS production at 4 h, suggesting that Cur is more active on ROS inhibition in the earlier phase of insult. Comparing the expression of NF-κB, Cur showed better anti-inflammatory action on NF-κB while Res did not have any effect of NF-κB expression at 4 h. Interestingly, Cur showed an upregulation of nuclear Nrf2 expression at 24 h whereas Res displayed no effect after 24 h incubation. Both Cur and Res inhibited the H₂O₂ induced translocation of Nrf2 into nucleus. In conclusion, based on our observation, we found that Cur and Res both protected astrocytes from oxidative stress. In addition, we observed that Cur is most effective in early hours of insult while Res is effective in late hours suggesting that Res may or may not have immediate effect on astrocytes.

Deregulation of Nrf2/ARE signaling pathway causes susceptibility of dystrophin-deficient myotubes to menadione-induced oxidative stress

Duchenne muscular dystrophy (DMD) is an X chromosome-linked disorder caused by a mutation in the dystrophin gene. Many previous studies reported that the skeletal muscles of DMD patients were more susceptible to oxidative stress than those of healthy people. However, not much has been known about the responsible mechanism of the differential susceptibility. In this study, we established dystrophin knock-down (DysKD) cell lines by transfection of dystrophin shRNA lentiviral particles into C2 cells and found that DysKD myotubes are more vulnerable to menadione-induced oxidative stress than control myotubes. We focused on the nuclear erythroid 2-related factor 2 (Nrf2) which is a transcription factor that regulates the expression of phase II antioxidant enzymes by binding to the antioxidant response element (ARE). Under menadione-induced oxidative stress, the translocation of Nrf2 to the nucleus is significantly decreased in the DysKD myotubes. In addition, the binding of Nrf2 to ARE site of Bcl-2 gene as well as protein expression of Bcl-2 is decreased compared to the control cells. Interestingly, sulforaphane increased Akt activation and Nrf2 translocation to the nucleus in the DysKD myotubes. These results suggest that the Nrf2 pathway might be the responsible pathway to the oxidative stress-induced muscle damage in DMD.

Noncanonical SQSTM1/p62-Nrf2 pathway activation mediates proteasome inhibitor resistance in multiple myeloma cells via redox, metabolic and translational reprogramming

Multiple Myeloma (MM) is a B-cell malignancy characterized by the accumulation of clonal plasma cells in the bone marrow, with drug resistance being a major cause of therapeutic failure. We established a carfilzomib-resistant derivative of the LP-1 MM cell line (LP-1/Cfz) and found that the transcription factor NF-E2 p45-related factor 2 (Nrf2; gene symbol NFE2L2) contributes to carfilzomib resistance. The mechanism of Nrf2 activation involved enhanced translation of Nrf2 as well as its positive regulator, the autophagy receptor sequestosome 1 (SQSTM1)/p62. The eukaryotic translation initiation factor gene EIF4E3 was among the Nrf2 target genes upregulated in LP-1/Cfz cells, suggesting existence of a positive feedback loop. In line with this, we found that siRNA knockdown of eIF4E3 decreased Nrf2 protein levels. On the other hand, elevated SQSTM1/p62 levels were due at least in part to activation of the PERK-eIF2α pathway. LP-1/Cfz cells had decreased levels of reactive oxygen species as well as elevated levels of fatty acid oxidation and prosurvival autophagy. Genetic and pharmacologic inhibition of the Nrf2-EIF4E3 axis or the PERK-eIF2α pathway, disruption of redox homeostasis or inhibition of fatty acid oxidation or autophagy conferred sensitivity to carfilzomib. Our findings were supported by clinical data where increased EIF4E3 expression was predictive of Nrf2 target gene upregulation in a subgroup of patients with chemoresistant minimal residual disease and relapsed/refractory MM. Thus, our data offer a preclinical rationale for including inhibitors of the SQSTM1/p62-Nrf2 pathway to the treatment regimens for certain advanced stage MM patients.

Nrf2 at the heart of oxidative stress and cardiac protection

The NFE2L2 gene encodes the transcription factor Nrf2 best known for regulating the expression of antioxidant and detoxification genes. Gene knockout approaches have demonstrated its universal cytoprotective features. While Nrf2 has been the topic of intensive research in cancer biology since its discovery in 1994, understanding the role of Nrf2 in cardiovascular disease has just begun. The literature concerning Nrf2 in experimental models of atherosclerosis, ischemia, reperfusion, cardiac hypertrophy, heart failure, and diabetes supports its cardiac protective character. In addition to antioxidant and detoxification genes, Nrf2 has been found to regulate genes participating in cell signaling, transcription, anabolic metabolism, autophagy, cell proliferation, extracellular matrix remodeling, and organ development, suggesting that Nrf2 governs damage resistance as well as wound repair and tissue remodeling. A long list of small molecules, most derived from natural products, have been characterized as Nrf2 inducers. These compounds disrupt Keap1-mediated Nrf2 ubquitination, thereby prohibiting proteasomal degradation and allowing Nrf2 protein to accumulate and translocate to the nucleus, where Nrf2 interacts with sMaf to bind to ARE in the promoter of genes. Recently alternative mechanisms driving Nrf2 protein increase have been revealed, including removal of Keap1 by autophagy due to p62/SQSTM1 binding, inhibition of βTrCP or Synoviolin/Hrd1-mediated ubiquitination of Nrf2, and de novo Nrf2 protein translation. We review here a large volume of literature reporting historical and recent discoveries about the function and regulation of Nrf2 gene. Multiple lines of evidence presented here support the potential of dialing up the Nrf2 pathway for cardiac protection in the clinic.

Molecular genetics and cellular events of K-Ras-driven tumorigenesis

Cellular transformation and the accumulation of genomic instability are the two key events required for tumorigenesis. K-Ras (Kirsten-rat sarcoma viral oncogene homolog) is a prominent oncogene that has been proven to drive tumorigenesis. K-Ras also modulates numerous genetic regulatory mechanisms and forms a large tumorigenesis network. In this review, we track the genetic aspects of K-Ras signaling networks and assemble the sequence of cellular events that constitute the tumorigenesis process, such as regulation of K-Ras expression (which is influenced by miRNA, small nucleolar RNA and lncRNA), activation of K-Ras (mutations), generation of reactive oxygen species (ROS), induction of DNA damage and apoptosis, induction of DNA damage repair pathways and ROS detoxification systems, cellular transformation after apoptosis by the blebbishield emergency program and the accumulation of genomic/chromosomal instability that leads to tumorigenesis.

Anti-inflammatory and antioxidant properties of Schisandrin C promote mitochondrial biogenesis in human dental pulp cells

AIM

To examine the properties of Schisandrin C as an anti-inflammatory and antioxidant compound, and whether its characteristics promote mitochondrial biogenesis in human dental pulp cells (HDPCs).

METHODOLOGY

HDPCs were extracted from fresh third molars and cultured for experiments. Reactive oxidative stress (ROS) and nitric oxide (NO) formation were analysed by a Muse cell analyser. Western blotting and gelatin zymography were used to identify the presence of antioxidants, as well as anti-inflammatory and mitochondrial biogenesis with specific antibody. An unpaired Student's t-test was used for statistical analysis.

RESULTS

Schisandrin C inhibited lipopolysaccharide-stimulated inflammatory molecules; interleukin 1 beta, tumour necrosis factor alpha, intracellular adhesion molecule-1, vascular cell adhesion molecule-1, matrix metalloproteinase-2 and -9, NO production, ROS formation, nuclear factor kappa B translocation (P < 0.05) through the mitogen-activated protein kinase pathway. Schisandrin C increased the expression of superoxide dismutase enzymes as well as haem oxygenase-1 and peroxisome proliferator-activated receptor gamma coactivator 1-alpha through the phosphorylated-protein kinase B (p-Akt) and nuclear factor erythroid 2-related factor-2 pathways (P < 0.05). The anti-inflammatory and antioxidant properties of Schisandrin C promoted mitochondrial biogenesis.

CONCLUSIONS

Schisandrin C has the potential to reduce inflammation and oxidation and to promote mitochondrial biogenesis. Therefore, Schisandrin C may be considered for use as an anti-inflammatory compound for oral inflammation through mitochondrial biogenesis.

Systems Approach Reveals Nuclear Factor Erythroid 2-Related Factor 2/Protein Kinase R Crosstalk in Human Cutaneous Leishmaniasis

Leishmania parasites infect macrophages, causing a wide spectrum of human diseases, from cutaneous to visceral forms. In search of novel therapeutic targets, we performed comprehensive in vitro and ex vivo mapping of the signaling pathways upstream and downstream of antioxidant transcription factor [nuclear factor erythroid 2-related factor 2 (Nrf2)] in cutaneous leishmaniasis (CL), by combining functional assays in human and murine macrophages with a systems biology analysis of in situ (skin biopsies) CL patient samples. First, we show the PKR pathway controls the expression and activation of Nrf2 in Leishmania amazonensis infection in vitro. Nrf2 activation also required PI3K/Akt signaling and autophagy mechanisms. Nrf2- or PKR/Akt-deficient macrophages exhibited increased levels of ROS/RNS and reduced expression of Sod1 Nrf2-dependent gene and reduced parasite load. L. amazonensis counteracted the Nrf2 inhibitor Keap1 through the upregulation of p62 via PKR. This Nrf2/Keap1 observation was confirmed in situ in skin biopsies from Leishmania-infected patients. Next, we explored the ex vivo transcriptome in CL patients, as compared to healthy controls. We found the antioxidant response element/Nrf2 signaling pathway was significantly upregulated in CL, including downstream target p62. In silico enrichment analysis confirmed upstream signaling by interferon and PI3K/Akt, and validated our in vitro findings. Our integrated in vitro, ex vivo, and in silico approach establish Nrf2 as a central player in human cutaneous leishmaniasis and reveal Nrf2/PKR crosstalk and PI3K/Akt pathways as potential therapeutic targets.

Pharmacological stimulation of nuclear factor (erythroid-derived 2)-like 2 translation activates antioxidant responses

Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is the master regulator of the antioxidant response, and its function is tightly regulated at the transcriptional, translational, and post-translational levels. It is well-known that Nrf2 is regulated at the protein level by proteasomal degradation via Kelch-like ECH-associated protein 1 (Keap1), but how Nrf2 is regulated at the translational level is less clear. Here, we show that pharmacological stimulation increases Nrf2 levels by overcoming basal translational repression. We developed a novel reporter assay that enabled identification of natural compounds that induce Nrf2 translation by a mechanism independent of Keap1-mediated degradation. Apigenin, resveratrol, and piceatannol all induced Nrf2 translation. More importantly, the pharmacologically induced Nrf2 overcomes Keap1 regulation, translocates to the nucleus, and activates the antioxidant response. We conclude that translational regulation controls physiological levels of Nrf2, and this can be modulated by apigenin, resveratrol, and piceatannol. Also, targeting this mechanism with novel compounds could provide new insights into prevention and treatment of multiple diseases in which oxidative stress plays a significant role.

Polyphenols from Lonicera caerulea L. Berry Inhibit LPS-Induced Inflammation through Dual Modulation of Inflammatory and Antioxidant Mediators

Lonicera caerulea L. berry polyphenols (LCBP) are considered as major components for bioactivity. This study aimed to clarify the molecular mechanisms by monitoring inflammatory and antioxidant mediator actions in lipopolysaccharide (LPS)-induced mouse paw edema and macrophage cell model. LCBP significantly attenuated LPS-induced paw edema (3.0 ± 0.1 to 2.8 ± 0.1 mm, P < 0.05) and reduced (P < 0.05) serum levels of monocyte chemotactic protein-1 (MCP-1, 100.9 ± 2.3 to 58.3 ± 14.5 ng/mL), interleukin (IL)-10 (1596.1 ± 424.3 to 709.7 ± 65.7 pg/mL), macrophage inflammatory protein (MIP)-1α (1761.9 ± 208.3 to 1369.1 ± 56.4 pg/mL), IL-6 (1262.8 ± 71.7 to 499.0 ± 67.1 pg/mL), IL-4 (93.3 ± 25.7 to 50.7 ± 12.5 pg/mL), IL-12(p-70) (580.4 ± 132.0 to 315.2 ± 35.1 pg/mL), and tumor necrosis factor-α (TNF-α, 2045.5 ± 264.9 to 1270.7 ± 158.6 pg/mL). Cell signaling analysis revealed that LCBP inhibited transforming growth factor β activated kinase-1 (TAK1)-mediated mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) pathways, and enhanced the expression of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) and manganese-dependent superoxide dismutase (MnSOD) in earlier response. Moreover, cyanidin 3-glucoside (C3G) and (-)-epicatechin (EC), two major components of LCBP, directly bound to TAK1. These data demonstrated that LCBP might inhibit LPS-induced inflammation by modulating both inflammatory and antioxidant mediators.

Dietary lipids differentially modulate the initiation of experimental breast carcinogenesis through their influence on hepatic xenobiotic metabolism and DNA damage in the mammary gland

Breast cancer is the most common malignancy among women worldwide. In addition to reproductive factors, environmental factors such as nutrition and xenobiotic exposure have a role in the etiology of this malignancy. A stimulating and a potentially protective effect on experimental breast cancer has been previously described for high corn oil and high extra-virgin olive oil diets, respectively. This work investigates the effect of these lipids on the metabolism of 7,12-dimethylbenz(a)anthracene (DMBA), a polycyclic aromatic hydrocarbon that can initiate carcinogenesis and its consequences in an experimental rat breast cancer model. The PUFA n-6-enriched diet increased expression of Phase I enzymes prior to DMBA administration and raised the activity of CYP1s in the hours immediately after induction, while reducing the activity of Phase II enzymes, mainly NQO1. The levels of reactive metabolites measured in plasma by GC-MS and DMBA-DNA adducts in the mammary gland of the animals fed the high corn oil diet were also higher than in the other groups. On the other hand, the high extra-virgin olive oil diet and the control low-fat diet exhibited better coordinated Phase I and Phase II activity, with a lower production of reactive metabolites and less DNA damage in the mammary gland. The concordance between these effects and the different efficacy of the carcinogenesis process due to the dietary treatment suggest that lipids may differently modify mammary gland susceptibility or resistance to cancer initiation over the exposure to environmental carcinogens.

SUMMARY

Dietary lipids influence the initiation of DMBA-induced mammary cancer through the modulation of liver xenobiotic metabolism, formation of reactive metabolites and subsequent DNA damage in the target tissue.

Casein Glycomacropeptide Hydrolysates Exert Cytoprotective Effect against Cellular Oxidative Stress by Up-Regulating HO-1 Expression in HepG2 Cells

Oxidative stress is considered as an important mediator in the progression of metabolic disorders. The objective of this study was to investigate the potential hepatoprotective effects and mechanisms of bovine casein glycomacropeptide hydrolysates (GHP) on hydrogen peroxide (H₂O₂)-induced oxidative damage in HepG2 cells. Results showed that GHP significantly blocked H₂O₂-induced intracellular reactive oxygen species (ROS) generation and cell viability reduction in a dose-dependent manner. Further, GHP concentration-dependently induced heme oxygenase-1 (HO-1) expression and increased nuclear factor-erythroid 2-related factor 2 (Nrf2) nuclear translocation. Moreover, pretreatment of GHP increased the activation of p38 mitogen-activated protein kinase (p38 MAPK) and extracellular signal-regulated protein kinase 1/2 (ERK1/2), which were shown to contribute to Nrf2-mediated HO-1 expression. Taken together, GHP protected HepG2 cells from oxidative stress by activation of Nrf2 and HO-1 via p38 MAPK and ERK1/2 signaling pathways. Our findings indicate that bovine casein glycomacropeptide hydrolysates might be a potential ingredient in the treatment of oxidative stress-related disorders and further studies are needed to investigate the protective effects in vivo.

G-Quadruplex in the NRF2 mRNA 5' Untranslated Region Regulates De Novo NRF2 Protein Translation under Oxidative Stress

Inhibition of protein synthesis serves as a general measure of cellular consequences of chemical stress. A few proteins are translated selectively and influence cell fate. How these proteins can bypass the general control of translation remains unknown. We found that low to mild doses of oxidants induce de novo translation of the NRF2 protein. Here we demonstrate the presence of a G-quadruplex structure in the 5' untranslated region (UTR) of NRF2 mRNA, as measured by circular dichroism, nuclear magnetic resonance, and dimethylsulfate footprinting analyses. Such a structure is important for 5'-UTR activity, since its removal by sequence mutation eliminated H₂O₂-induced activation of the NRF2 5' UTR. Liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based proteomics revealed elongation factor 1 alpha (EF1a) as a protein binding to the G-quadruplex sequence. Cells responded to H₂O₂ treatment by increasing the EF1a protein association with NRF2 mRNA, as measured by RNA-protein interaction assays. The EF1a interaction with small and large subunits of ribosomes did not appear to change due to H₂O₂ treatment, nor did posttranslational modifications, as measured by two-dimensional (2-D) Western blot analysis. Since NRF2 encodes a transcription factor essential for protection against tissue injury, our data have revealed a novel mechanism of cellular defense involving de novo NRF2 protein translation governed by the EF1a interaction with the G-quadruplex in the NRF2 5' UTR during oxidative stress.

Nrf2 mediates redox adaptations to exercise

The primary aim of this review is to summarize the current literature on the effects of acute exercise and regular exercise on nuclear factor erythroid 2-related factor 2 (Nrf2) activity and downstream targets of Nrf2 signaling. Nrf2 (encoded in humans by the NFE2L2 gene) is the master regulator of antioxidant defenses, a transcription factor that regulates expression of more than 200 cytoprotective genes. Increasing evidence indicates that Nrf2 signaling plays a key role in how oxidative stress mediates the beneficial effects of exercise. Episodic increases in oxidative stress induced through bouts of acute exercise stimulate Nrf2 activation and when applied repeatedly, as with regular exercise, leads to upregulation of endogenous antioxidant defenses and overall greater ability to counteract the damaging effects of oxidative stress. The evidence of Nrf2 activation in response to exercise across variety of tissues may be an important mechanism of how exercise exerts its well-known systemic effects that are not limited to skeletal muscle and myocardium. Additionally there are emerging data that results from animal studies translate to humans.

Modulatory effects of new curcumin analogues on gamma-irradiation - Induced nephrotoxicity in rats

In the present study, a new series of 2-amino-pyran-3-carbonitrile derivatives of curcumin 2-7 have been synthesized via one-pot simple and efficient protocol, involving the reaction of curcumin 1 with substituted-benzylidene-malononitrile to modify the 1,3-diketone moiety. The structures of the synthesized compounds 2-7 were elucidated by microanalytical and spectral data, which were found consistent with the assigned structures. The nephroprotective mechanism of these new curcumin analogues was evaluated on the post-gamma-irradiation (7 Gy) - induced nephrotoxicity in rats. Activation of Nrf2 by these curcumin analogues is responsible for the amendment of the antioxidant status, impairment of NF-κB signal, thus attenuate the nephrotoxicity induced post-γ-irradiation exposure. 4-Chloro-phenyl curcumin analogue 7 showed the most potent activity. In conclusion, the results of the present study demonstrate a promising role of these new curcumin analogues to attenuate the early symptoms of nephrotoxicity induced by γ-irradiation in rats via activation of Nrf2 gene expression. These new curcumin analogues need further toxicological investigations to assess their therapeutic index.

Modulation of the Nrf2 signalling pathway in Hct116 colon carcinoma cells by baicalein and its methylated derivative negletein

CONTEXT

Baicalein is a major compound in extracts derived from Scutellaria baicalensis Georgi (Lamiaceae) which are used in the Traditional Chinese Medicine for the treatment of inflammatory and gastrointestinal diseases. This flavonoid is an activator of the Nrf2 signalling pathway but the molecular mechanism is not clearly established.

OBJECTIVE

We investigated the molecular mode of baicalein-mediated Nrf2-activation in Hct116 cells by the analysis of proteasomal activity, radical-scavenging activity and the comparison with baicalein derivatives.

MATERIALS AND METHODS

The radical-scavenging activity (TEAC, DCF) up to 25 μM, cytotoxicity (MTT assay, 48 h) up to 100 μM, proteasomal activity and the Nrf2-activation (luciferase assay, ubiquitinylation, western blot, Ser40-phosphorylation; incubation for 1 or 4 h) by concentrations up to 40 or 50 μM of the compounds were analysed in Hct116 human colon carcinoma cells.

RESULTS

No change in the ubiquitinylation of Nrf2, proteasomal activity and transcription of the NRF2 gene were detectable. Baicalein decreased the phosphorylation of Nrf2 (IC50-value approximately 20 μM) suggesting an inhibitory effect of the flavonoid on protein kinases. Since the activation of the Nrf2 pathway by baicalein might be also due to redox-activity of the compound, we investigated the effects of methylated baicalein derivatives oroxylin A, negeletein and baicaleintrimethylether. Oroxylin A and negletein showed a comparable redox-active potential, but only negletein (50 μM, 4 h) was able to activate Nrf2.

CONCLUSION

This result confirms the hypothesis that baicalein, a component of extracts derived from Baical Skullcap, causes an activation of Nrf2 independent of a modulation of the cellular redox potential.

Permethrin-induced oxidative stress and toxicity and metabolism. A review

Permethrin (PER), the most frequently used synthetic Type I pyrethroid insecticide, is widely used in the world because of its high activity as an insecticide and its low mammalian toxicity. It was originally believed that PER exhibited low toxicity on untargeted animals. However, as its use became more extensive worldwide, increasing evidence suggested that PER might have a variety of toxic effects on animals and humans alike, such as neurotoxicity, immunotoxicity, cardiotoxicity, hepatotoxicity, reproductive, genotoxic, and haematotoxic effects, digestive system toxicity, and cytotoxicity. A growing number of studies indicate that oxidative stress played critical roles in the various toxicities associated with PER. To date, almost no review has addressed the toxicity of PER correlated with oxidative stress. The focus of this article is primarily to summarise advances in the research associated with oxidative stress as a potential mechanism for PER-induced toxicity as well as its metabolism. This review summarises the research conducted over the past decade into the reactive oxygen species (ROS) generation and oxidative stress as a consequence of PER treatments, and ultimately their correlation with the toxicity and the metabolism of PER. The metabolism of PER involves various CYP450 enzymes, alcohol or aldehyde dehydrogenases for oxidation and the carboxylesterases for hydrolysis, through which oxidative stress might occur, and such metabolic factors are also reviewed. The protection of a variety of antioxidants against PER-induced toxicity is also discussed, in order to further understand the role of oxidative stress in PER-induced toxicity. This review will throw new light on the critical roles of oxidative stress in PER-induced toxicity, as well as on the blind spots that still exist in the understanding of PER metabolism, the cellular effects in terms of apoptosis and cell signaling pathways, and finally strategies to help to protect against its oxidative damage.

Endothelial HO-1 induction by model TG-rich lipoproteins is regulated through a NOX4-Nrf2 pathway

Circulating levels of chylomicron remnants (CMRs) increase postprandially and their composition directly reflects dietary lipid intake. These TG-rich lipoproteins likely contribute to the development of endothelial dysfunction, albeit via unknown mechanisms. Here, we investigated how the FA composition of CMRs influences their actions on human aortic endothelial cells (HAECs) by comparing the effects of model CMRs-artificial TG-rich CMR-like particles (A-CRLPs)-containing TGs extracted from fish, DHA-rich algal, corn, or palm oils. HAECs responded with distinct transcriptional programs according to A-CRLP TG content and oxidation status, with genes involved in antioxidant defense and cytoprotection most prominently affected by n-3 PUFA-containing A-CRLPs. These particles were significantly more efficacious inducers of heme oxygenase-1 (HO-1) than n-6 PUFA corn or saturated FA-rich palm CRLPs. Mechanistically, HO-1 induction by all CRLPs requires NADPH oxidase 4, with PUFA-containing particles additionally dependent upon mitochondrial reactive oxygen species. Activation of both p38 MAPK and PPARβ/δ culminates in increased nuclear factor erythroid 2-related factor 2 (Nrf2) expression/nuclear translocation and HO-1 induction. These studies define new molecular pathways coupling endothelial cell activation by model CMRs with adaptive regulation of Nrf2-dependent HO-1 expression and may represent key mechanisms through which dietary FAs differentially impact progression of endothelial dysfunction.

Argon protects against hypoxic-ischemic brain injury in neonatal rats through activation of nuclear factor (erythroid-derived 2)-like 2

Perinatal hypoxic ischaemic encephalopathy (HIE) has a high mortality rate with neuropsychological impairment. This study investigated the neuroprotective effects of argon against neonatal hypoxic-ischaemic brain injury.In vitro cortical neuronal cell cultures derived from rat foetuses were subjected to an oxygen and glucose deprivation (OGD) challenge for 90 minutes and then exposed to 70% argon or nitrogen with 5% carbon dioxide and balanced with oxygen for 2 hours.In vivo, seven-day-old rats were subjected to unilateral common carotid artery ligation followed by hypoxic (8% oxygen balanced with nitrogen) insult for 90 minutes. They were exposed to 70% argon or nitrogen balanced with oxygen for 2 hours. In vitro, argon treatment of cortical neuronal cultures resulted in a significant increase of p-mTOR and Nuclear factor (erythroid-derived 2)-like 2(Nrf2) and protection against OGD challenge. Inhibition of m-TOR through Rapamycin or Nrf2 through siRNA abolished argon-mediated cyto-protection. In vivo, argon exposure significantly enhanced Nrf2 and its down-stream effector NAD(P)H Dehydrogenase, Quinone 1(NQO1) and superoxide dismutase 1(SOD1). Oxidative stress, neuroinflammation and neuronal cell death were significantly decreased and brain infarction was markedly reduced. Blocking PI-3K through wortmannin or ERK1/2 through U0126 attenuated argon-mediated neuroprotection.These data provide a new molecular mechanism for the potential application of Argon as a neuroprotectant in HIE.

Preexposure to Olive Oil Polyphenols Extract Increases Oxidative Load and Improves Liver Mass Restoration after Hepatectomy in Mice via Stress-Sensitive Genes

Polyphenols can act as oxidants in some conditions, inducing redox-sensitive genes. We investigated the effect of preexposure to the olive oil polyphenols extract (PFE) on time-dependent changes in the hepatic oxidative state in a model of liver regeneration—a process in which oxidative stress associated with the metabolic overload accounts for the early events that contribute to the onset of liver self-repair. Liver regeneration was induced by one-third hepatectomy in mice. Prior to hepatectomy, mice were intraperitoneally given either PFE (50 mg/kg body weight) or saline for seven consecutive days, while respective controls received vehicle alone. Redox state-regulating enzymes and thiol proteins along with the mRNA levels of Nrf2 gene and its targets γ-glutamylcysteine synthetase and heme oxygenase-1 were determined at different time intervals after hepatectomy. The liver mass restoration was calculated to assess hepatic regeneration. The resulting data demonstrate the effectiveness of preexposure to PFE in stimulating liver regeneration in a model of a small tissue loss which may be ascribed to the transient increase in oxidant load during the first hours after hepatectomy and associated induction of stress response gene-profiles under the control of Nrf2.