Regulation Of Nrf2 Research Articles

Adverse Effects of Oxidative Stress on Bone and Vasculature in Corticosteroid-Associated Osteonecrosis: Potential Role of Nuclear Factor Erythroid 2-Related Factor 2 in Cytoprotection.

Significance: Osteonecrosis (ON) is characterized by bone tissue death due to disturbance of the nutrient artery. The detailed process leading to the necrotic changes has not been fully elucidated. Clinically, high-dose corticosteroid therapy is one of the main culprits behind osteonecrosis of the femoral head (ONFH). Recent Advances: Numerous studies have proposed that such ischemia concerns various intravascular mechanisms. Of all reported risk factors, the involvement of oxidative stress in the irreversible damage suffered by bone-related and vascular endothelial cells during ischemia simply cannot be overlooked. Several articles also have sought to elucidate oxidative stress in relation to ON using animal models or in vitro cell cultures. Critical Issues: However, as far as we know, antioxidant monotherapy has still not succeeded in preventing ONFH in humans. To provide this desideratum, we herein summarize the current knowledge about the influence of oxidative stress on ON, together with data about the preventive effects of administering antioxidants in corticosteroid-induced ON animal models. Moreover, oxidative stress is counteracted by nuclear factor erythroid 2-related factor 2 (Nrf2)-dependent cytoprotective network through regulating antioxidant expressions. Therefore, we also describe Nrf2 regulation and highlight its role in the pathology of ON. Future Directions: This is a review of all available literature to date aimed at developing a deeper understanding of the pathological mechanism behind ON from the perspective of oxidative stress. It may be hoped that this synthesis will spark the development of a prophylactic strategy to benefit corticosteroid-associated ONFH patients. Antioxid. Redox Signal. 35, 357-376.

Protective effects of curcumin on chemical and drug-induced cardiotoxicity: a review.

Cardiotoxicity is a major adverse effect that can be induced by both therapeutic agents and industrial chemicals. The pathogenesis of such cardiac damage is multifactorial, often injuring the cardiac tissue by generating free radicals, oxidative stress, and/or inflammation. Curcumin (CUR) is a bright yellow chemical produced by Curcuma longa plants. It is the principal curcuminoid of turmeric (Curcuma longa), a member of the ginger family, Zingiberaceae. Administration of CUR has been reported to ameliorate the chemical and drug-induced cardiac injury in several studies. CUR has been suggested to act as an effective candidate against oxidative stress and inflammation in heart tissue via regulation of Nrf2 and suppression of p38 MAPK/NF-κB and NLRP3 inflammasomes. The anti-apoptotic properties of CUR have also been reported to modulate the AMPK, Akt, JNK, and ERK signaling pathways. This review explores the potential protective effects of CUR regarding the detrimental effects often observed in cardiac tissue following exposure to several chemicals including drugs.

Corilagin induces apoptosis and autophagy in NRF2‑addicted U251 glioma cell line

Corilagin, extracted from the Euphorbiaceae and Phyllanthus plants, inhibits the growth of a number of types of tumors. Compared with temozolomide, the traditional chemotherapy drug, corilagin has demonstrated stronger antitumor activity. However, the pharmaceutical mechanism of corilagin in glioma remains unclear. Nuclear factor erythroid 2 like 2 (NFE2L2 or NRF2) is positively associated with several types of tumor including glioma. In the present study, NRF2 expression was higher in glioma tissues compared with non-glioma specimens. Therefore, it was hypothesized that corilagin targets NRF2 regulation of U251 cell apoptosis. The present study used Hoechst 33258 staining to demonstrate that corilagin induced glioma cell apoptosis and observed that the expression of the apoptosis-related gene Bcl-2 was reduced. In addition, corilagin induced autophagy and promoted the conversion of light chain 3 (LC3) protein from LC3I to LC3II. NRF2 expression was downregulated by corilagin stimulation. Furthermore, the gene expression pattern following knockdown of NRF2 in U251 cells using siRNA was consistent with corilagin stimulation. Therefore, it was preliminarily concluded that corilagin induces apoptosis and autophagy by reducing NRF2 expression.

Therapeutic modulation of the phosphatidylinositol 3-kinases (PI3K) pathway in cerebral ischemic injury

The cerebral ischemic reperfusion injury may leads to morbidity and mortality in patients. phosphatidylinositol 3-kinase (PI3K) signaling pathway has been believed to work in association with its downstream targets, other receptors, and pathways that may offer antioxidant, anti-inflammatory, anti-apoptotic effects, neuroprotective role in neuronal excitotoxicity. This review elaborates the mechanistic interventions of the PI3K pathway in cerebral ischemic injury in context to nuclear factor erythroid 2–related factor 2 (Nrf2) regulation, Hypoxia-inducible factor 1 signaling (HIF-1), growth factors, Endothelial NOS (eNOS) proinflammatory cytokines, Erythropoietin (EPO), Phosphatase and tensin homologous protein of chromosome 10 gene (PTEN) signaling, NF-κB/Notch signaling, c-Jun N-terminal kinase (JNK) and Glycogen synthase kinase-3β (GSK-3β) signaling pathway. Evidences showing the activation of PI3K inhibits apoptotic pathway, which results in its neuroprotective effect in ischemic injury. Despite discussing the therapeutic role of the PI3K pathway in treating cerebral ischemic injury, the review also enlighten the selective modulation of PI3K pathway with activators and inhibitors which may provide promising results in clinical and preclinical settings.

Maqui berry extract prevents cigarette smoke induced oxidative stress in human osteoblasts in vitro.

Oxidative stress which can be induced by cigarette smoke (CS) is associated with an altered osteoblast differentiation, and an inhibition of the mineralization process. Therefore, treatments focusing on reducing oxidative stress in osteoblasts could be a potential therapy supporting bone formation. Maqui berry extract (MBE) is the richest natural source of delphinidins with high antioxidant activity. In the present study, we pre-/ co-/ post-incubated MBE in cigarette smoke extract (CSE)-affected human osteoblasts (hOBs), to investigate the effects of MBE as an antioxidant on hOBs. Our results clearly showed that high concentrations of MBE are toxic for hOBs, while physiological concentrations of MBE have no negative effects in vitro. Physiological concentrations of MBE can reduce oxidative stress caused by CSE in hOBs by activating the antioxidative regulator Nrf2 and its regulated antioxidative enzymes. Moreover, the physiological concentration of MBE prevents the detrimental effects of CSE-induced oxidative damage on hOBs by increasing cell viability, differentiation capability and matrix mineralization. Pre-incubation with MBE showed a positive effect on the activation of the cellular antioxidant system in hOBs. Thus, we conclude that MBE at physiological concentrations can effectively protect osteoblasts from oxidative stress-induced damage by activating the cells' antioxidative defense system.

NRF2 Activation Confers Resistance to eIF4A Inhibitors in Cancer Therapy.

Simple SummaryeIF4A-targeted translational inhibitors, such as silvestrol and its analogues, have emerged as strong anticancer therapies. Here, we tested the efficacy of eIF4A inhibition across a large and diverse panel of cancer cell lines and found B cell lymphomas to be the most sensitive group. Moreover, we performed a genetic screen and identified NRF2 activation as a major mechanism of resistance to silvestrol and related eIF4A inhibitors. Mechanistically, NRF2 activation broadly increases protein synthesis, and this effect is more pronounced on specific mRNAs that require eIF4A for translation. Finally, blocking NRF2 function by preventing its deglycation restores silvestrol sensitivity in cells that harbor NRF2 activation. Overall, our findings indicate that eIF4A inhibitors are a feasible therapeutic option against lymphoma and other cancers and that NRF2 activation status may be an important predictor of their efficacy.Inhibition of the eIF4A RNA helicase with silvestrol and related compounds is emerging as a powerful anti-cancer strategy. We find that a synthetic silvestrol analogue (CR-1-31 B) has nanomolar activity across many cancer cell lines. It is especially active against aggressive MYC+/BCL2+ B cell lymphomas and this likely reflects the eIF4A-dependent translation of both MYC and BCL2. We performed a genome-wide CRISPR/Cas9 screen and identified mechanisms of resistance to this new class of therapeutics. We identify three negative NRF2 regulators (KEAP1, CUL3, CAND1) whose inactivation is sufficient to cause CR1-31-B resistance. NRF2 is known to alter the oxidation state of translation factors and cause a broad increase in protein production. We find that NRF2 activation particularly increases the translation of some eIF4A-dependent mRNAs and restores MYC and BCL2 production. We know that NRF2 functions depend on removal of sugar adducts by the frutosamine-3-kinase (FN3K). Accordingly, loss of FN3K results in NRF2 hyper-glycation and inactivation and resensitizes cancer cells to eIF4A inhibition. Together, our findings implicate NRF2 in the translation of eIF4A-dependent mRNAs and point to FN3K inhibition as a new strategy to block NRF2 functions in cancer.

Rosmarinic acid protects rats against post-stroke depression after transient focal cerebral ischemic injury through enhancing antioxidant response

Rosmarinic acid (RA), a natural polyphenol, possesses potent antioxidant and anti-inflammatory activities. To evaluate the ability of RA to cure ischemic stroke and post-stroke depression (PSD), rats were treated with various doses of RA after cerebral ischemia. Neurological deficits and infarct volume of the brain were measured. The activities of superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH) were examined at different time points. In addition, a forced swimming test and sucrose preference test were performed to detect the anti-depressive effects of RA. Our results revealed RA administration significantly alleviated neurological deficits and reduced infarct volumes. RA attenuated the decrease of SOD, CAT activities and GSH levels in the ischemic penumbra of the brain. Most importantly, RA treatment alleviated the depression behaviors. Increased expression of Nrf2 was also induced by RA, while down regulation Nrf2 by Nrf2-short-hairpin RNA sequences reversed the increasing activity of SOD and CAT induced by RA, as well as the protection against PSD. The present study indicates that RA exerts a potent neuroprotective effect against stroke and PSD, which could be a promising therapeutic intervention for stroke.

Evaluation of the therapeutic effects of mycophenolate mofetil targeting Nrf-2 and NLRP3 inflammasome in acetic acid induced ulcerative colitis in rats

Ulcerative colitis (UC) is a chronic inflammatory bowel disease that increases the risk of colorectal cancer. UC is highly associated with the disturbance of the immune system leading to oxidative stress and chronic inflammation of intestine. Therefore, the current study was conducted to investigate the potential anti-oxidant and anti-inflammatory effects of MMF against acetic acid-induced UC that might be associated with the regulation of Nrf-2 and NLRP3 inflammasome signaling. UC was induced in Sprague-Dawley rats by intracolonic instillation of acetic acid. Forty-eight hours post UC induction, MMF (50 mg/kg/day, orally) was given for 8 consecutive days. Then, colon tissues and blood samples were collected. Results showed that MMF significantly attenuated the acetic acid-induced functional, biochemical, and inflammatory injuries in colon. MMF significantly decreased oxidative stress as indicated by the decreased malondialdehyde concentration and the increased total antioxidant capacity, glutathione, catalase, and superoxide dismutase concentrations in colon tissues. MMF also significantly increased Nrf-2 and decreased NLRP3 inflammasome expressions. Moreover, MMF decreased expression of interferon-gamma and increased expression of interferon-alpha. MMF also significantly decreased expression of pro-inflammatory cytokines, interleukin (IL)-1β and IL-18. These results suggest that MMF has antioxidant and anti-inflammatory effects against acetic acid-induced UC through the upregulation of Nrf-2, and INF-α expression in addition to the suppression of NLRP3 inflammasome and subsequent release of IL1β, IL-18 and INF-γ.

Nephroprotective effect of umbelliferone against cisplatin-induced kidney damage is mediated by regulation of NRF2, cytoglobin, SIRT1/FOXO-3, and NF- kB-p65 signaling pathways.

Cisplatin (Cis) is one of the most potent and effective broad-spectrum antitumor drugs, but its use is limited due to nephrotoxicity. The current study investigated the renoprotective effect of umbelliferone (UMB) on Cis-induced nephrotoxicity in rats. Renal injury was induced by a single injection of Cis (7 mg/kg, ip). Our results exhibited that the injection of Cis significantly disrupted renal function biomarkers as well as KIM-1 expression. The expressions of TNF-α, IL-1β, NF-kB-p65, and IKKβ were elevated along with downregulation of IkBα expression. Also, Cis disrupted cellular oxidant/antioxidant balance through the reduction of glutathione (GSH), glutathione-S-transferase (GST), and superoxide dismutase (SOD) levels and elevation of malondialdehyde (MDA) content. On the contrary, the levels of renal function biomarkers, cytokines, NF-kB-p65, IkBα, IKKβ, and oxidant/antioxidant status have been improved after UMB treatment. Mechanistically, rats administered Cis only exhibited a significant decrease in NRF2 and cytoglobin expressions as well as the CREB, SIRT1, FOXO-3, and PPAR-γ genes. Treatment with UMB significantly upregulated NRF2 and cytoglobin proteins, as well as effectively increased the expression of CREB, SIRT1, FOXO-3, PPAR-γ, and NRF2 genes. Histopathological findings strongly supported our biochemical results, as evidenced by attenuation of renal hemorrhage, cast diffusion, and inflammatory cell infiltration. Interestingly, UMB significantly enhanced Cis cytotoxicity in both HL-60 and HeLa cells in a dose-dependent manner. Together, our results demonstrated that UMB can protect against Cis-induced nephrotoxicity in normal rats along with the enhancement of its in vitro antitumor activity. These findings suggested that UMB could be used as a potential adjuvant therapy in Cis chemotherapeutic protocols.

Altered expression of clock and clock-controlled genes in a hSOD1-linked amyotrophic lateral sclerosis mouse model.

Most physiological processes in mammals are subjected to daily oscillations that are governed by a circadian system. The circadian rhythm orchestrates metabolic pathways in a time-dependent manner and loss of circadian timekeeping has been associated with cellular and system-wide alterations in metabolism, redox homeostasis, and inflammation. Here, we investigated the expression of clock and clock-controlled genes in multiple tissues (suprachiasmatic nucleus, spinal cord, gastrocnemius muscle, and liver) from mutant hSOD1-linked amyotrophic lateral sclerosis (ALS) mouse models. We identified tissue-specific changes in the relative expression, as well as altered daily expression patterns, of clock genes, sirtuins (Sirt1, Sirt3, and Sirt6), metabolic enzymes (Pfkfb3, Cpt1, and Nampt), and redox regulators (Nrf2, G6pd, and Pgd). In addition, astrocytes transdifferentiated from induced pluripotent stem cells from SOD1-linked and FUS RNA binding protein-linked ALS patients also displayed altered expression of clock genes. Overall, our results raise the possibility of disrupted cross-talk between the suprachiasmatic nucleus and peripheral tissues in hSOD1G93A mice, preventing proper peripheral clock regulation and synchronization. Since these changes were observed in symptomatic mice, it remains unclear whether this dysregulation directly drives or it is a consequence of the degenerative process. However, because metabolism and redox homeostasis are intimately entangled with circadian rhythms, our data suggest that altered expression of clock genes may contribute to metabolic and redox impairment in ALS. Since circadian dyssynchrony can be rescued, these results provide the groundwork for potential disease-modifying interventions.

XCT/SLC7A11 antiporter function inhibits HIV-1 infection

Human macrophages are protected by intrinsic antiviral defenses that provide moderate protection against HIV-1 infection. Macrophages that do become infected can serve as long-lived reservoirs, to disseminate HIV-1 to CD4+ T cells. Infection of macrophages with HIV-1 and HIV-2 is inhibited by constitutive mobilization of antioxidant response master transcription regulator Nrf2. The downstream mediator of this restriction was not identified. Among the tens of genes controlled directly by Nrf2 in macrophages, we found that xCT/SLC7A11, a 12-transmembrane, cystine-glutamate antiporter promotes antiretroviral activity. We show here that depletion of xCT mRNA increases HIV-1 infection. Reconstitution of xCT knock out cells with wild-type xCT but not a transport-deficient mutant restores anti-HIV-1 activity. Pharmacological inhibitors of xCT amino acid transport also increase infection. The block is independent of known restriction factors and acts against HIV-1 and HIV-2. Like the block triggered through Nrf2, xCT function impedes infection immediately before 2-LTR circle formation.

The impact of ellagic acid on some apoptotic gene expressions: a new perspective for the regulation of pancreatic Nrf-2/NF-κB and Akt/VEGF signaling in CCl4-induced pancreas damage in rats

Objective The aim of this study was to evaluate the potential effect of ellagic acid (EA) in the treatment of pancreatic injury. EA has been found to have strong anti-inflammatory, antioxidative, and anticancer properties. The effects of EA on pancreati˜c star cell (PSC) activation and cell functions have been evaluated and it has been shown that it inhibits the activation of basic cell functions and PSCs and. it has antidiabetic activity through its effect on β-pancreas cells. Materials and methods In this work, 36 Wistar albino rats (n = 36, 8 weeks old) were used. Rats were divided to 4 groups and 9 rats were each group. Groups: Group 1: control group; Group 2: EA group; Group 3: carbon tetrachloride (CCl4) group; Group 4: EA + CCl4 group. Animals were decapitated after 8 weeks and their pancreas tissue samples were taken and researched. In pancreas tissue, NF-κB, TNF-α, Nrf-2, VEGF, Bcl-2, caspase-3, and Akt proteins expression ratios were analyzed by western blotting method, CAT activity and GSH levels were determined by spectrophotometer and ROS production was detected by MDA. Results In our results, the Nrf-2 and caspase-3 protein expressions, catalase activities and GSH levels increased, TNF-α, NF-κB, Bcl-2, VEGF, and Akt protein expressions and MDA levels reduced in EA + CCl4 group comparable to the CCl4 group. Conclusions These findings reveal that EA decreases pancreas tissue injury in rats and that EA may also be used as a drug against pancreas tissue injury in the future.

UBXN7 cofactor of CRL3KEAP1 and CRL2VHL ubiquitin ligase complexes mediates reciprocal regulation of NRF2 and HIF-1α proteins

UBXN7 is a cofactor protein that provides a scaffold for both CRL3KEAP1 and CRL2VHL ubiquitin ligase complexes involved in the regulation of the NRF2 and HIF-1α protein levels respectively. NRF2 and HIF-1α are surveillance transcription factors that orchestrate the cellular response to oxidative stress (NRF2) or to hypoxia (HIF-1α). Since mitochondria are the main oxygen sensors as well as the principal producers of ROS, it can be presumed that they may be able to modulate the activity of CRL3KEAP1 and CRL2VHL complexes in response to stress. We have uncovered a new mechanism of such regulation that involves the UBXN7 cofactor protein and its regulation by mitochondrial MUL1 E3 ubiquitin ligase. High level of UBXN7 leads to HIF-1α accumulation, whereas low level of UBXN7 correlates with an increase in NRF2 protein. The reciprocal regulation of HIF-1α and NRF2 by UBXN7 is coordinated under conditions of oxidative stress or hypoxia. In addition, this molecular mechanism leads to different metabolic states; high level of UBXN7 and accumulation of HIF-1α support glycolysis, whereas inactivation of UBXN7 and activation of NRF2 confer increased OXPHOS. We describe a new mechanism by which MUL1 E3 ubiquitin ligase modulates the UBXN7 cofactor protein level and provides a reciprocal regulation of CRL3KEAP1 and CRL2VHL ubiquitin ligase complexes. Furthermore, we delineate how this regulation is reflected in NRF2 and HIF-1α accumulation and determines the metabolic state as well as the adaptive response to mitochondrial stress.

Differential effects of arsenic species on Nrf2 and Bach1 nuclear localization in cultured hepatocytes

Arsenic is a ubiquitous metalloid element present in both inorganic and organic forms in the environment. The liver is considered to be a primary organ of arsenic biotransformation and methylation, as well as the main target of arsenic toxicity. Studies have confirmed that Chang human hepatocytes have an efficient arsenic methylating capacity. Our previous studies have proven that arsenite activates nuclear factor erythroid 2-related factor 2 (Nrf2) pathway in hepatocytes. This study aimed to explore the activation of the Nrf2 pathway upon treatment of arsenic in various forms, including inorganic and organic arsenic. Our results showed that inorganic arsenic—both As2O3 and Na2HAsO4 significantly induced the expression of Nrf2 protein and mRNA, enhanced the transcription activity of Nrf2, and induced the expression of downstream target genes. These results confirmed the inorganic arsenic-induced Nrf2 pathway activation in hepatocytes. Although all arsenic chemicals used in the study induced Nrf2 protein accumulation, the organic arsenic C2H7AsO2 did not affect the expression of Nrf2 downstream genes which were elevated by inorganic arsenic exposures. Through qRT-PCR and Nrf2 luciferase reporter assays, we further confirmed that C2H7AsO2 neither increased Nrf2 mRNA level nor activated the Nrf2 transcription activity. Mechanistically, our results confirmed inorganic arsenic-induced both the nuclear import of Nrf2 and export of Bach1 (BTB and CNC homology 1), which is an Nrf2 transcriptional repressor, while organic arsenic only induced Nrf2 translocation. The unique pattern of Nrf2 regulation by organic arsenic underlines the critical role of Nrf2 and Bach1 in the arsenic toxicology.

Different Sources of Dietary Magnesium Supplementation Reduces Oxidative Stress by Regulation Nrf2 and NF-κB Signaling Pathways in High-Fat Diet Rats.

Magnesium (Mg) is an essential mineral required for many physiological processes, including ionic balances in ocular tissues. We compared the effects of different Mg-chelates (Mg oxide, MgO vs. Mg picolinate, MgPic) on retinal function in a high-fat diet (HFD) rats. Forty-two rats were divided into six groups and treated orally for 8 weeks as follows: Control, MgO, MgPic, HFD, HFD + MgO, and HFD + MgPic. Mg was administered at 500 mg of elemental Mg/kg of diet. HFD intake increased the levels of retinal MDA and NF-κB, INOS, ICAM, and VEGF but downregulated Nrf2. However, in rats supplemented with MgO and MgPic, the retinal MDA level was decreased, compared with the control and HFD rats. Activities of antioxidant enzymes (SOD, CAT, and GPx) were increased in HFD animals given Mg-chelates (p < 0.001), MgPic being the most effective. Mg supplementation significantly decreased the expression levels of NF-κB, INOS, ICAM, and VEGF in HFD rats while increasing the level of Nrf2 (p < 0.001). Mg supplementation significantly decreased the levels of NF-κB, INOS, ICAM, and VEGF and increased Nrf2 level in HFD rats (p < 0.001), with stronger effects seen from MgPic. Mg attenuated retinal oxidative stress and neuronal inflammation and could be considered as an effective treatment for ocular diseases.

MiR-144 is the epigenetic target for emodin to ameliorate oxidative stress induced by dietary oxidized fish oil via Nrf2 signaling in Wuchang bream, Megalobrama amblycephala

Oxidative stress caused by external stressors could induce severe cellular and tissue injury, even induce immune impairment or unexpected death. This study was aimed to uncover the underlying epigenetic mechanism of miRNAs in response to oxidative stress under emodin stimulation in Megalobrama amblycephala intestine. RNA-sequencing reveals 60 differentially expressed genes (DEGs) under oxidative stress were mainly function in metabolic, intestinal inflammation, and virus defense signaling. mRNA-miRNA co-expression networks reveal dynamically regulated miRNAs by oxidative stress to be largely embedded in energy metabolism, oxidative homeostasis, cell apoptosis and cancerization signaling. Specifically, PI3K-Akt, focal adhesion, MAPK, and Nrf2-Keap1 signaling were dysregulated by miR-144, miR-155, and miR-200a. Binding site prediction shown miR-144 inhibits Nrf2, miR-155 inhibits PI3K and Bach1, and miR-200a inhibits MAPK1 and Keap1 by targeting to their 3’-UTR. Mechanistically, miR-144 was solidly confirmed as the negative regulator of Nrf2 by dual luciferase reporter assay. With qRT-PCR analysis, we found emodin alleviates oxidative stress through activating miR-144, miR-155, and miR-200a expression and subsequently downregulating the PI3K-Akt, MAPKs, and Nrf2-Keap1 pathway at the post-translational level. Herein, the epigenetic schematic indicates miR-144, miR-155, and miR-200a are target miRs for emodin to resist oxidative stress along with MAPKs, PI3K-Akt, and Nrf2-Keap1 signaling. Taken together, our findings suggest that miR-144/Nrf2 could serve as genetic modifiers of nutrient-related injury stress and could provide novel insights into the therapeutic effects of emodin on oxidized lipid induced oxidative stress in M. amblycephala.

Cullin3 aggravates the inflammatory response of periodontal ligament stem cells via regulation of SHH signaling and Nrf2

ABSTRACT It is found that the activation of Sonic Hedgehog (SHH) signaling pathway is related to the degree of inflammation in patients suffering from periodontitis. Cullin3 (CUL3), an important ubiquitin ligase, can control SHH signaling. In this study, we were dedicated to clarify the roles of SHH and CUL3 in P. gingivalis-LPS (Pg-LPS)-treated periodontal ligament stem cells (PDLSCs). In this study, cell viability was detected using cell counting kit-8 (CCK-8). The inflammatory cytokines of PDLSCs were estimated by enzyme-linked immunosorbent assay (ELISA). With the application of western blots, the protein levels of SHH, Gli1 and NF-E2-related factor 2 (Nrf2) were determined. Alkaline phosphatase staining and Alizarin red staining were performed to evaluate the differentiation and mineralization capabilities of PDLSCs. The apoptotic cells were screened using TUNEL staining. The results showed that Pg-LPS inhibited cell viability and triggered inflammation of PDLSCs. Overexpression of CUL3 weakened the differentiation and mineralization capabilities of PDLSCs. Moreover, CUL3 overexpression aggravated inflammation and cell apoptosis induced by Pg-LPS. It is worth noting that although the protein levels of SHH, Gli1 and Nrf2 were elevated in PDLSCs treated with Pg-LPS, overexpression of CUL3 decreased the expressions of Gli1 and Nrf2. Overall, SHH/Gli1 and Nrf2 were involved in the inflammation and cell apoptosis of PDLSCs, which was dominated by CUL3.

Bisphenol A stabilizes Nrf2 via Ca2+ influx by direct activation of the IP3 receptor.

Bisphenol A (BPA) is an endocrine-disrupting chemical used in polycarbonate and epoxy resins. Previously, we found that BPA stabilized the protein levels of nuclear factor erythroid 2-related factor 2 (Nrf2) by inducing Ca2+ efflux into the cytosol, followed by nitric oxide synthase activation, resulting in the enhanced nitrosylation of Keap1, which is a negative regulator of Nrf2. However, the mechanisms behind the stimulation of Ca2+ efflux by BPA remain unknown. In the present study, we found that BPA stimulated Ca2+ efflux into the cytosol from the ER, but not from outside of cells through the plasma membrane in Hep3B cells. Ca2+ efflux and Nrf2 stabilization by BPA were inhibited by an inhibitor of the inositol 1,4,5-trisphosphate (IP3) receptor, 2-aminoethoxydiphenylborane, in the endoplasmic reticulum. IP3 is produced by activation of phospholipase C (PLC) from a membrane lipid, phosphatidylinositol 4,5-bisphosphate (PIP2). The induction of Nrf2 by BPA was not inhibited by a PLC inhibitor, U-73122, suggesting that BPA does not induce the production of IP3 via PLC activation. We found that BPA bound directly to the IP3 binding core domain of the IP3 receptor, and BPA competed with IP3 on this site. In addition, overexpression of this domain of the IP3 receptor in Hep3B cells inhibited the stabilization of Nrf2 by BPA. These results clarified that the IP3 receptor is a new target of BPA, and that BPA induces Ca2+ efflux from the endoplasmic reticulum via activation of the IP3 receptor.

Nuclear factor erythroid 2-related factor 2 modulates HER4 receptor in ovarian cancer cells to influence their sensitivity to tyrosine kinase inhibitors.

Aim: Nuclear factor erythroid 2-related factor 2 (NRF2) is a key component in the cell’s response to oxidative and electrophilic stress and is a transcription factor regulating the expression of a collection of anti-oxidative and cytoprotective genes. Human epidermal growth factor receptor 4 (HER4/erbB4) regulates growth and differentiation in many cancer types. Here, NRF2 and HER4 receptor interactions were investigated in a panel of ovarian cancer cell lines.Methods: Pharmacological [tert-butylhydroquinone (tBHQ) and retinoid/rexinoid, bexarotene] and genetic [small interfering RNA (siRNA)] manipulations were used to activate or inhibit NRF2 function in the cell line panel (PE01, OVCAR3, SKOV3). Activity of the HER-targeted tyrosine kinase inhibitors, erlotinib (ERL) and lapatinib (LAP), was evaluated after NRF2 activation.Results: While tBHQ increased the levels of both phosphorylated-NRF2 (pNRF2) and HER4 in PE01, OVCAR3 and SKOV3 cells, bexatorene and NRF2-target siRNA treatment decreased pNRF2 and total HER4 levels. The tBHQ-dependent pharmacological activation of NRF2 attenuated the therapeutic effectiveness of ERL and LAP. Analyses of gene expression data from a HER4 driven reporter system and in vitro or in vivo cancer models, support NRF2 regulation of HER4 expression.Conclusions: These results support the presence of signaling interaction between the NRF2 and HER4 receptor pathways and suggest that intervention modulating this cross-talk could have anticancer therapeutic value.

NRF2 Regulation by Noncoding RNAs in Cancers: The Present Knowledge and the Way Forward.

Simple SummaryThe NRF2 pathway represents one of the most intriguing pathways that promotes chemo- and radioresistance of neoplastic cells. Increasing findings suggest that the NRF2 signaling can be modulated by multiple epigenetic factors such as noncoding RNAs, which influence a large number of oncogenic mechanisms, both at transcriptional and at post-transcriptional levels. As a consequence, the identification and characterization of specific noncoding RNAs as biomarkers related to oxidative stress may help to clarify the relationship between them and NRF2 signaling in the tumor context, in terms of positive and negative modulation, also referring to their intersection with other NRF2 crosstalking pathways. In this review, we summarize the recent updates on NRF2 network regulation by noncoding RNAs in tumors, thus paving the way toward the potential translational role of these small RNAs as key tumor biomarkers of neoplastic processes.Nuclear factor erythroid 2-related factor 2 (NRF2) is the key transcription factor triggered by oxidative stress that moves in cells of the antioxidant response element (ARE)-antioxidant gene network against reactive oxygen species (ROS) cellular damage. In tumors, the NRF2 pathway represents one of the most intriguing pathways that promotes chemo- and radioresistance of neoplastic cells and its activity is regulated by genetic and epigenetic mechanisms; some of these being poorly investigated in cancer. The noncoding RNA (ncRNA) network is governed by microRNAs (miRNAs) and long noncoding RNAs (lncRNAs) and modulates a variety of cellular mechanisms linked to cancer onset and progression, both at transcriptional and post-transcriptional levels. In recent years, the scientific findings about the effects of ncRNA landscape variations on NRF2 machines are rapidly increasing and need to be continuously updated. Here, we review the latest knowledge about the link between NRF2 and ncRNA networks in cancer, thus focusing on their potential translational significance as key tumor biomarkers.