Reactive Oxygen Species Signaling Pathways Research Articles

Oroxylin A regulates the turnover of lipid droplet via downregulating adipose triglyceride lipase (ATGL) in hepatic stellate cells

Proliferation and differentiation of hepatic stellate cells (HSCs) are the most noticeable events in hepatic fibrosis, in which the loss of lipid droplets (LDs) is the most important feature. However, the complex mechanisms of LD disappearance have not been fully elucidated. In the current study, we investigated whether oroxylin A has the pharmacological activity of reversing LDs in activated HSCs, and further examined its potential molecular mechanisms. Using genetic, pharmacological, and molecular biological measure, we found that LD content significantly decreased during HSC activation, whereas oroxylin A markedly reversed LD content in activated HSCs. Interestingly, oroxylin A treatment observably decreased the expression of adipose triglyceride lipase (ATGL) without large differences in classical LD synthesis pathway, LD-related transcription factors, and autophagy pathway. ATGL overexpression could completely impair the effect of oroxylin A on reversing LD content. Importantly, reactive oxygen species (ROS) signaling pathway mediated oroxylin A-induced ATGL downregulation and LD revision in activated HSCs. ROS specific stimulant buthionine sulfoximine (BSO) could dramatically diminish the antioxidant effect of oroxylin A, and in turn, abolish reversal effect of oroxylin A on LD content. Conversely, ROS specific scavenger N-acetyl cystenine (NAC) can significantly enhance the pharmacological effect of oroxylin A on LD revision. Taken together, our study reveals the important molecular mechanism of anti-fibrosis effect of oroxylin A, and also suggests that ROS-ATGL pathway is a potential target for reversing LDs.

Advanced Glycation End Products (AGEs) Induce Apoptosis of Fibroblasts by Activation of NLRP3 Inflammasome via Reactive Oxygen Species (ROS) Signaling Pathway.

BackgroundType 2 diabetes impairs the healing process and induces apoptosis of fibroblasts, which are thought to be involved in this process. We investigated the possible mechanisms involved in AGEs-induced apoptosis of human dermal fibroblasts.Material/MethodsWe examined the expression of apoptosis-related proteins in fibroblasts isolated from human diabetic wounds. Human dermal fibroblasts exposed to AGEs were used to study the links among apoptosis, ROS, and NLRP3 inflammasome activation. Signaling mechanisms were evaluated by preincubating the cells with appropriate inhibitors. Cleaved caspase-8, cleaved caspase-3, BAX, Bcl-2, and NLRP3 inflammasome expression were measured by Western blot analysis. ROS generation, cell viability, and cell apoptosis were assessed.ResultsWe observed a higher level of cleaved caspase-8 and cleaved caspase-3 expression in fibroblasts isolated from human diabetic wounds compared with controls. AGEs decreased the proliferation of cells in a concentration-dependent and time-dependent manner. The exposure of fibroblasts to AGEs significantly increased the number of cells in early and late apoptosis stages. AGES-induced human dermal fibroblasts showed high expressions of cleaved caspase3, cleaved caspase8, and Bax. Treatment with AGEs induced the expression of NLRP3, caspase-1, and ASC. AGES-induced apoptosis was blocked by BAY 11–7082, an inhibitor of the NLRP3 inflammasome. AGEs increased the production of ROS in fibroblasts, and its apoptogenic effect was blocked by NAC.ConclusionsAGEs cause apoptosis of fibroblasts by inducing the generation of ROS and activating the NLRP3 inflammasome. In vivo experiments are needed to confirm these results.

Glutamine Metabolism Is Essential for Stemness of Bone Marrow Mesenchymal Stem Cells and Bone Homeostasis.

Skeleton has emerged as an endocrine organ which is both capable of regulating energy metabolism and being a target for it. Glutamine is the most bountiful and flexible amino acid in the body which provides adenosine 5′-triphosphate (ATP) demands for cells. Emerging evidences support that glutamine which acts as the second metabolic regulator after glucose exerts crucial roles in bone homeostasis at cellular level, including the lineage allocation and proliferation of bone mesenchymal stem cells (BMSCs), the matrix mineralization of osteoblasts, and the biosynthesis in chondrocytes. The integrated mechanism consisting of WNT, mammalian target of rapamycin (mTOR), and reactive oxygen species (ROS) signaling pathway in a glutamine-dependent pattern is responsible to regulate the complex intrinsic biological process, despite more extensive molecules are deserved to be elucidated in glutamine metabolism further. Indeed, dysfunctional glutamine metabolism enhances the development of degenerative bone diseases, such as osteoporosis and osteoarthritis, and glutamine or glutamine progenitor supplementation can partially restore bone defects which may promote treatment of bone diseases, although the mechanisms are not quite clear. In this review, we will summarize and update the latest research findings and clinical trials on the crucial regulatory roles of glutamine metabolism in BMSCs and BMSC-derived bone cells, also followed with the osteoclasts which are important in bone resorption.

Wheat methionine sulfoxide reductase A4.1 interacts with heme oxygenase 1 to enhance seedling tolerance to salinity or drought stress.

Here, a functional characterization of a wheat MSR has been presented: this protein makes a contribution to the plant's tolerance of abiotic stress, acting through its catalytic capacity and its modulation of ROS and ABA pathways. The molecular mechanism and function of certain members of the methionine sulfoxide reductase (MSR) gene family have been defined, however, these analyses have not included the wheat equivalents. The wheat MSR gene TaMSRA4.1 is inducible by salinity and drought stress and in this study, we demonstrate that its activity is restricted to the Met-S-SO enantiomer, and its subcellular localization is in the chloroplast. Furthermore, constitutive expression of TaMSRA4.1 enhanced the salinity and drought tolerance of wheat and Arabidopsis thaliana. In these plants constitutively expressing TaMSRA4.1, the accumulation of reactive oxygen species (ROS) was found to be influenced through the modulation of genes encoding proteins involved in ROS signaling, generation and scavenging, while the level of endogenous abscisic acid (ABA), and the sensitivity of stomatal guard cells to exogenous ABA, was increased. A yeast two-hybrid screen, bimolecular fluorescence complementation and co-immunoprecipitation assays demonstrated that heme oxygenase 1 (HO1) interacted with TaMSRA4.1, and that this interaction depended on a TaHO1 C-terminal domain. In plants subjected to salinity or drought stress, TaMSRA4.1 reversed the oxidation of TaHO1, activating ROS and ABA signaling pathways, but not in the absence of HO1. The aforementioned properties advocate TaMSRA4.1 as a candidate for plant genetic enhancement.

The Role of Serine-Threonine Protein Phosphatase PP2A in Plant Oxidative Stress Signaling-Facts and Hypotheses.

Abiotic and biotic factors induce oxidative stress involving the production and scavenging of reactive oxygen species (ROS). This review is a survey of well-known and possible roles of serine-threonine protein phosphatases in plant oxidative stress signaling, with special emphasis on PP2A. ROS mediated signaling involves three interrelated pathways: (i) perception of extracellular ROS triggers signal transduction pathways, leading to DNA damage and/or the production of antioxidants; (ii) external signals induce intracellular ROS generation that triggers the relevant signaling pathways and (iii) external signals mediate protein phosphorylation dependent signaling pathway(s), leading to the expression of ROS producing enzymes like NADPH oxidases. All pathways involve inactivation of serine-threonine protein phosphatases. The metal dependent phosphatase PP2C has a negative regulatory function during ABA mediated ROS signaling. PP2A is the most abundant protein phosphatase in eukaryotic cells. Inhibitors of PP2A exert a ROS inducing activity as well and we suggest that there is a direct relationship between these two effects of drugs. We present current findings and hypotheses regarding PP2A-ROS signaling connections related to all three ROS signaling pathways and anticipate future research directions for this field. These mechanisms have implications in the understanding of stress tolerance of vascular plants, having applications regarding crop improvement.

β-Cyclocitral is a conserved root growth regulator

Natural compounds capable of increasing root depth and branching are desirable tools for enhancing stress tolerance in crops. We devised a sensitized screen to identify natural metabolites capable of regulating root traits in Arabidopsis β-Cyclocitral, an endogenous root compound, was found to promote cell divisions in root meristems and stimulate lateral root branching. β-Cyclocitral rescued meristematic cell divisions in ccd1ccd4 biosynthesis mutants, and β-cyclocitral-driven root growth was found to be independent of auxin, brassinosteroid, and reactive oxygen species signaling pathways. β-Cyclocitral had a conserved effect on root growth in tomato and rice and generated significantly more compact crown root systems in rice. Moreover, β-cyclocitral treatment enhanced plant vigor in rice plants exposed to salt-contaminated soil. These results indicate that β-cyclocitral is a broadly effective root growth promoter in both monocots and eudicots and could be a valuable tool to enhance crop vigor under environmental stress.

Baicalein ameliorates pristane-induced lupus nephritis via activating Nrf2/HO-1 in myeloid-derived suppressor cells

IntroductionLupus nephritis (LN) is a representative manifestation in systemic lupus erythematosus (SLE). Some studies have shown that myeloid-derived suppressor cells (MDSCs) play a vital role in the regulation of the SLE process. MDSC infiltration in the kidney as well as inflammation and oxidative stress provokes the acceleration and deterioration of LN. Nuclear factor E2-related factor 2 (Nrf2) is thought to be a major regulator of the antioxidant response. Baicalein is a flavonoid with known anti-inflammatory effects and antioxidant response. However, the effects of baicalein on MDSCs, inflammation, and oxidative stress are not evaluated in the development of pristane-induced LN in mice.MethodsThe renoprotective effect of baicalein was detected in a pristane-induced lupus mice model. NLRP3 inflammasome activation and NF-κB phosphorylation as well as reactive oxygen species (ROS) production and Nrf2 activation were examined. The percentages and function changes of MDSCs were measured. The possible mechanisms of the underlying effects of baicalein on ROS production and signaling pathways of Nrf2/heme-oxygenase (HO)-1, NLRP3 inflammasome, and NF-κB phosphorylation in lipopolysaccharide (LPS)-primed MDSCs were analyzed.ResultsBaicalein reduced proteinuria and attenuated renal function impairment and renal histopathology including intrinsic cell proliferation, cellular crescents, and podocyte injury as well as glomerulonephritis activity in lupus mice. Moreover, baicalein downregulated the activation of NLRP3 inflammasome and levels of ROS or NF-κB phosphorylation, and it enhanced Nrf2 activation. Of note, baicalein inhibited the expansion of MDSCs and improved the function of MDSCs in lupus mice. Through analyzing LPS-primed MDSCs in vitro, baicalein was found to exhibit cytoprotective effects coincident with the induction of Nrf2/HO-1 signaling and the suppression of the NLRP3 inflammasome.ConclusionThe data show that baicalein alleviates the symptoms of pristane-induced LN and suggest that the alleviation may be attributed to inhibition of MDSC expansion and regulation of the balance of the Nrf2/HO-1 signal and NLRP3 expression in MDSCs.

Disruption of a Upf1-like helicase-encoding gene OsPLS2 triggers light-dependent premature leaf senescence in rice.

The OsPLS2 locus was isolated and cloned by map-based cloning that encodes a Upf1-like helicase. Disruption of OsPLS2 accelerated light-dependent leaf senescence in the rice mutant of ospls2. Leaf senescence is a very complex physiological process controlled by both genetic and environmental factors, however its underlying molecular mechanisms remain elusive. In this study, we report a novel Oryza sativa premature leaf senescence mutant (ospls2). Through map-based cloning, a G-to-A substitution was determined at the 1st nucleotide of the 13th intron in the OsPLS2 gene that encodes a Upf1-like helicase. This mutation prompts aberrant splicing of OsPLS2 messenger and consequent disruption of its full-length protein translation, suggesting a negative role of OsPLS2 in regulating leaf senescence. Wild-type rice accordingly displayed a progressive drop of OsPSL2 protein levels with age-dependent leaf senescence. Shading and light filtration studies showed that the ospls2 phenotype, which was characteristic of photo-oxidative stress and reactive oxygen species (ROS) accumulation, was an effect of irritation by light. When continuously exposed to far-red light, exogenous H2O2 and/or abscisic acid (ABA), the ospls2 mutant sustained hypersensitive leaf senescence. In consistence, light and ROS signal pathways in ospls2 were activated by down-regulation of phytochrome genes, and up-regulation of PHYTOCHROME-INTERACTING FACTORS (PIFs) and WRKY genes, all promoting leaf senescence. Together, these data indicated that OsPLS2 played an essential role in leaf senescence and its disruption triggered light-dependent leaf senescence in rice.

Programmed cell death induced by cadmium stress and/or boron deprivation in tobacco (Nicotiana tabacum L.) cultivar Bright Yellow 2 cells

Cadmium (Cd) is one of the most toxic and widespread heavy metal pollutants in soil. As an essential mineral nutrient, boron (B) plays critical roles in physiological processes of plants. In the present study, programmed cell death (PCD) induced by Cd stress and/or B deprivation was assessed and the underlying mechanisms were clarified in suspension-cultured Nicotiana tabacum L. cultivar Bright Yellow 2 (TBY-2) cells. The PCD in TBY-2 cells was analyzed by Hoechst 33258 staining and the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, and then, expression analysis of PCD-related genes was performed using quantitative real-time polymerase chain reaction (qPCR) assays. The production of reactive oxygen species (ROS) was determined using fluorescence microscopy of 2′,7′-dichlorofluorescein diacetate–labeled cells. The levels of lipid peroxides were quantified by the thiobarbituric acid–reactive substances (TBARS) method. Cadmium stress and/or B deprivation treatments induced PCD that was characterized by a significant increase in the percentage of cells stained with Hoechst 33258 or TUNEL-positive cells, and upregulation or downregulation of the expression of PCD-related genes. Treatments with Cd stress and/or B deprivation increased ROS production and the level of lipid peroxides compared to those of the control group. These data showed that in TBY-2 cells Cd stress and/or B deprivation activated ROS signaling pathways, leading to gene expression that was connected with the PCD process.

Lanthanum elicitation on hypocrellin A production in mycelium cultures of Shiraia bambusicola is mediated by ROS generation

Rare earth elements (REEs) have been widely applied as efficient elicitors to improve production of biologically important secondary metabolites in plants. However, their effects on microbial secondary metabolites were seldom reported. In this study, lanthanum (LaCl3) was used as an elicitor in mycelium cultures of Shiraia bambusicola to stimulate the production of hypocrellin A (HA), a promising photosensitizer for anticancer photodynamic therapy. La3+ at 1.0 g/L not only increases HA content by 2.50-fold in mycelia, but stimulates HA exudation to the medium with the highest production (225.05 mg/L) on day 6. Further analysis shows that La3+ can induce the intracellular ROS (reactive oxygen species) accumulation with 2.33-fold higher contents of H2O2 in mycelium. HA production induced by La3+ treatment can be suppressed by ROS scavengers. Further analysis reveals that the elicitation of La3+ on HA accumulation is mediated by ROS generation to enhance expression of HA biosynthetical genes. The expression of ATP-binding cassette transporter gene (SbABC) for HA exudation is also regulated partially via ROS generated by NADPH oxidase. These results indicate that the enhanced HA production by La3+ might be mediated by ROS signaling pathway. Our results provide a basis for understanding REE elicitation on fungal metabolites and a practical biotechnological process for enhanced production of HA.

The Dual Neuroprotective-Neurotoxic Effects of Sevoflurane After Hemorrhagic Shock Injury

BackgroundThe neuroprotection and neurotoxicity induced by sevoflurane have been gradually established. Choosing anesthetic agents after hemorrhage shock and resuscitation (HSR) induced by bleeding can be challenging. We determined the dual neuroprotective-neurotoxic effects of sevoflurane postconditioning after HSR injury using a model of blood loss and reinfusion in rats via the heme oxygenase-1 (HO-1)/reactive oxygen species (ROS) signal pathway. MethodsThe rats were exposed to 2%-4% sevoflurane postconditioning in vivo after HSR. Learning ability was assessed 30 d after HSR by Morris water maze tests. Hippocampal apoptosis was assessed 7 d after HSR by TdT-mediated dUTP nick-end labeling combined with cleaved caspase-3 (17 kDa). The ROS, mitochondrial membrane potential (MMP), HO-1 expression, and HO activity 1 d after HSR were assessed by fluorometric, JC-1, Western blot, and bilirubin assays, respectively. ResultsCompared with HSR alone, 2% sevoflurane postconditioning improved latency and increased MMP levels, HO-1 expression, and HO activity but decreased TdT-mediated dUTP nick-end labeling-positive cells, cleaved caspase-3 (17 kDa) expression, and ROS production. Pretreatment with hemin, an HO-1 agonist, reversed these effects. Compared with 2% sevoflurane postconditioning plus HSR, slower latency; decreased MMP levels; and increased TdT-mediated dUTP nick-end labeling-positive cells, cleaved caspase-3 (17 kDa), HO-1 expression, HO activity, and ROS production were shown in HSR plus 4% sevoflurane postconditioning, whereas Tin-mesoporphyrin, an HO-1 inhibitor, partially reversed the neurodegeneration of 4% sevoflurane postconditioning. ConclusionThe dual neuroprotective-neurotoxic effects of 2%-4% sevoflurane postconditioning after HSR injury might be associated with increased ROS via the “threshold effect” of HO-1.

Effect of lentivirus-mediated overexpression or silencing of MnSOD on apoptosis of resveratrol-treated fibroblast-like synoviocytes in rheumatoid arthritis

Fibroblast-like synoviocytes in rheumatoid arthritis (RA-FLSs) play a key role in cartilage destruction. We previously found that resveratrol (Res) could promote FLSs apoptosis in adjuvant arthritis rats, but the underlying mechanism was unclear. According to our latest study, Res can suppress the expression of mitochondrial superoxide dismutase (MnSOD) and RA-FLSs proliferation. It was associated with elevated mitochondrial reactive oxygen species levels. Therefore, we hypothesized that Res-mediated RA-FLSs apoptosis might occur via the MnSOD- mitochondrial reactive oxygen species pathway. RA-FLSs were infected with lentiviruses and screened with puromycin at a concentration of 8 µg/ml. We divided the RA-FLSs into four groups: a control group, a negative control (NC) group, a MnSOD overexpression group, and a MnSOD RNAi group. The four groups of RA-FLSs were tested using confocal laser scanning microscopy, CCK-8 assays, flow cytometry, and western blotting were conducted to determine the involvement of the MnSOD-mitochondrial reactive oxygen species pathway. Compared with the NC group, the MnSOD overexpression group treated with different concentrations of Res (0, 25, 50, 100, or 200 μM) and 5 μM H2O2 showed reduced levels of mitochondrial reactive oxygen species, increased B-cell-lymphoma-2 (Bcl-2), reduced Bcl-2 Associated X protein (Bax), and fewer apoptotic cells. The MnSOD RNAi group showed the opposite results. Thus, we concluded that Res could facilitate RA-FLSs apoptosis by regulating MnSOD expression and mitochondrial reactive oxygen species levels. Our findings show a novel mechanism for the beneficial effects of Res, especially in relation to the MnSOD-mitochondrial reactive oxygen species signaling pathway in RA.

A Potential Mechanism for the Antioxidant Compound Kushen Injection Targeting the ROS Signaling Pathway in Acute Myeloid Leukemia

AbstractIt is a challenge for treatment of acute myeloid leukemia (AML) in clinic. The increase in the levels of reactive oxygen species (ROS) in AML patients has been previously described; thus, it is important to regulate ROS levels in AML.In this study, we found that intracellular ROS levels in AML cells were decreased, the total antioxidant capacity (T-AOC) and glutathione (GSH) contents were increased and xanthine oxidase (XOD) vitality was decreased when treated with the compound kushen injection (CKI). This shows that CKI inhibited the proliferation of AML cell lines and patient cells and enhanced the cytotoxicity of AML cells, which has few toxic effects on haematopoietic stem cells (HSCs) and T cells. At the single-cell level, individual AML cells died gradually by CKI treatment on optofluidic chips. CKI could promote apoptosis and arrest cell cycle at G1/G0 phase in U937 cells.Furthermore, higher peroxiredoxin-3 (Prdx3) expression levels were found in CKI-treated U937 cells through quantitative proteomics detection. Mechanically, the expression of Prdx3 and peroxiredoxin-2 (Prdx2) was up-regulated in CKI-treated AML cells, while thioredoxin 1 (Trx1) was reduced. Laser confocal microscopy showed that the Prdx2 and Trx1 proteins could be co-localized by CKI treatment.In vivo, in the CKI-treated group, survival was longer in an AML patient-derived xenograft model in B-NSG mice. The disease was partially alleviated by decreased CD45+ immunophenotyping in peripheral blood and bone marrow smear analysis. After CKI injection, the T-AOC vitality, GSH content and CAT activity increased and the concentration of H2O2decreased in mouse plasma. A bone marrow biopsy and immunohistochemistry analysis showed that Prdx3 and Prdx2 expression was increased, while Trx1 expression was decreased.In a conclusion, we provided a model for the anti-leukaemic effects of CKI. CKI decreased intracellular ROS levels by up-regulating the expression of Prdx2 in the cytoplasm and Prdx3 in the mitochondria and down-regulating Trx1 expression, which maintained the intracellular REDOX and further inhibited AML cell proliferation.Therefore, antioxidant CKI is a promising drug for the treatment of AML in the clinic. We aimed to explore the therapeutic efficacy of low toxicity natural antioxidants against AML by targeting ROS pathways and providing new strategies to improve survival in AML patients. DisclosuresNo relevant conflicts of interest to declare.

Effect of carbon monoxide postconditioning on pyroptosis induced by oxygen-glucose deprivation and restoration in rat hippocampal neurons: the relationship with mPTP/ROS signaling pathway

Objective To evaluate the effect of carbon monoxide(CO) postconditioning on pyroptosis induced by oxygen-glucose deprivation and restoration(OGD/R) in rat hippocampal neurons and the relationship with mitochondrial permeability transition pore(mPTP)/reactive oxygen species(ROS) signaling pathway. Methods Primary hippocampal neurons were cultured in vitro, seed in 6-well or 96-well plates, and divided into 5 groups(n=24 each) using a random number table method: control group(C group), OGD/R group, CO postconditioning group(CO group), specific mPTP opener atractyloside plus CO postconditioning group(ACO group), and specific ROS inducer antimycin A plus CO postconditioning group(KCO group). Neurons were subjected to O2-glucose deprivation(OGD) for 16 h followed by restoration of O2 -glucose supply for 24 h to establish the model of OGD/R injury. In group CO, neurons were exposed to 2% CO-5% CO2 for 3 h at 37 ℃ starting from the end of OGD, followed by normal culture for 21 h. In ACO and KCO groups, atractyloside 20 μmol/L and antimycin A 50 μmol/L were added at the end of OGD, respectively, and the other treatments were similar to those previously described in group CO. Neuronal pyroptosis rate was determined using double immunofluorescent staining cleaved caspase-1-AlexaFluor 568/DAPI after the end of treatments in each group. The neuronal survival rate was determined by MTT, opening of mPTP by Calcein-AM fluorescence, ROS content by DCFH-DA, and expression of interleukin-1beta(IL-1β) and IL-18 by Western blot. Results Compared with C group, neuronal pyroptosis rate, ROS content and opening of mPTP were significantly increased, the neuronal survival rate was decreased, and the expression of IL-1β and IL-18 was up-regulated in the other groups(P<0.05). Compared with OGD/R group, neuronal pyroptosis rate, ROS content and opening of mPTP were significantly decreased, the neuronal survival rate was increased, and the expression of IL-1β and IL-18 was down-regulated in CO, ACO and KCO groups(P<0.05). Compared with CO group, neuronal pyroptosis rate and ROS content were significantly increased, the neuronal survival rate was decreased, and the expression of IL-1β and IL-18 was up-regulated in ACO and KCO groups, and opening of mPTP was significantly inctreased in ACO group(P<0.05). Conclusion CO postconditioning can inhibit OGD/R-induced pyroptosis in rat hippocampal neurons, and the mechanism is related to inhibiting mPTP/ROS signaling pathway. Key words: Carbon monoxide; Neurons; Cell death; Reperfusion injury; Reactive oxygen species; Mitochondrial membrane transport proteins

Heme oxygenase-1 reduces the sensitivity to imatinib through nonselective activation of histone deacetylases in chronic myeloid leukemia.

Resistance towards imatinib (IM) remains troublesome in treating many chronic myeloid leukemia (CML) patients. Heme oxygenase-1 (HO-1) is a key enzyme of antioxidative metabolism in association with cell resistance to apoptosis. Our previous studies have shown that overexpression of HO-1 resulted in resistance development to IM in CML cells, while the mechanism remains unclear. In the current study, the IM-resistant CML cells K562R indicated upregulation of some of the histone deacetylases (HDACs) compared with K562 cells. Therefore, we herein postulated HO-1 was associated with HDACs. Silencing HO-1 expression in K562R cells inhibited the expression of some HDACs, and the sensitivity to IM was increased. K562 cells transfected with HO-1 resisted IM and underwent obvious some HDACs. These findings related to the inhibitory effects of high HO-1 expression on the reactive oxygen species (ROS) signaling pathway that negatively regulated HDACs. Increased expression of HO-1 activated HDACs by inhibiting ROS production. In summary, HO-1, which is involved in the development of drug resistance in CML cells by regulating the expression of HDACs, is probably a novel target for improving CML therapy.

Suppressing ROS-TFE3-dependent autophagy enhances ivermectin-induced apoptosis in human melanoma cells.

Melanoma is an aggressive skin malignancy with a high mortality rate; however, successful treatment remains a clinical challenge. Ivermectin, a broad-spectrum antiparasitic drug, has recently been characterized as a potential anticancer agent due to its observed antitumor effects. However, the molecular mechanisms of ivermectin remain poorly understood. In the current study, we tested the involvement of autophagy in the ivermectin mechanism of action in human melanoma cells. We exposed SK-MEL-28 cells to different concentrations of ivermectin (2.5, 5, and 10 μM) for 24 hours. Here, ivermectin-induced apoptosis, as evidenced by the upregulation of cleaved poly (ADP-ribose) polymerase, BAX expression, and caspase-3 activity and downregulation of BCL-2 expression. In line with the apoptosis response, ivermectin triggered autophagy. Pharmacological or genetic inhibition of autophagy further sensitized SK-MEL-28 cells to ivermectin-induced apoptosis. Mechanistically, ivermectin-induced TFE3(Ser321) dephosphorylation, activated TFE3 nuclear translocation and increased TFE3 reporter activity, which contributed to lysosomal biogenesis and the expression of autophagy-related genes, and subsequently, initiated autophagy in SK-MEL-28 cells. Moreover, N-acetyl-cysteine, an reactive oxygen species (ROS) scavenger, abrogated the effects of ivermectin on TFE3-dependent autophagy. Taken together, we demonstrated that ivermectin increases TFE3-dependent autophagy through ROS signaling pathways in human melanoma cells and that inhibiting autophagy enhances ivermectin-induced apoptosis in human melanoma cells.

ROS generation and MAPKs activation contribute to the Ni-induced testosterone synthesis disturbance in rat Leydig cells

Nickel (Ni) can disorder testosterone synthesis in rat Leydig cells, whereas the mechanisms remain unclear. The aim of this study was to investigate the role of reactive oxygen species (ROS) and mitogen-activated protein kinases (MAPKs) in Ni-induced disturbance of testosterone synthesis in rat Leydig cells. The testosterone production and ROS levels were detected in Leydig cells. The mRNA and protein levels of testosterone synthetase, including StAR, CYP11A1, 3β-HSD, CYP17A1 and 17β-HSD, were determined. Effects of Ni on the ERK1/2, p38 and JNK MAPKs were also investigated. The results showed that Ni triggered ROS generation, consequently resulted in the decrease of testosterone synthetase expression and testosterone production in Leydig cells, which were then attenuated by ROS scavengers of N-acetylcysteine (NAC) and 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO), indicating that ROS are involved in the Ni-induced testosterone biosynthesis disturbance. Meanwhile Ni activated the ERK1/2, p38 and JNK MAPKs. Furthermore, Ni-inhibited testosterone synthetase expression levels and testosterone secretion were all alleviated by co-treatment with MAPK specific inhibitors (U0126 and SB203580, respectively), implying that Ni inhibited testosterone synthesis through activating ERK1/2 and p38 MAPK signal pathways in Leydig cells. In conclusion, these findings suggest that Ni causes testosterone synthesis disorder, partly, via ROS and MAPK signal pathways.

Interplay between the unfolded protein response and reactive oxygen species: a dynamic duo.

Secretory proteins undergo modifications such as glycosylation and disulphide bond formation before proper folding, and move to their final destination via the endomembrane system. Accumulation of unfolded proteins in the endoplasmic reticulum (ER) due to suboptimal environmental conditions triggers a response called the unfolded protein response (UPR), which induces a set of genes that elevate protein folding capacity in the ER. This review aims to establish a connection among ER stress, UPR, and reactive oxygen species (ROS), which remains an unexplored topic in plants. For this, we focused on mechanisms of ROS production originating from ER stress, the interaction between ER stress and overall ROS signalling process in the cell, and the interaction of ER stress with other organellar ROS signalling pathways such as of the mitochondria and chloroplasts. The roles of the UPR during plant hormone signalling and abiotic and biotic stress responses are also discussed in connection with redox and ROS signalling.

Hydrogen-rich water mediates redox regulation of the antioxidant system, mycelial regeneration and fruiting body development in Hypsizygus marmoreus

Hypsizygus marmoreus is an important industrialized mushroom, yet the lack of basic research on this fungus has hindered further development of its economic value. In this study, mycelia injured by scratching were treated with hydrogen-rich water (HRW) to investigate the involvement of the redox system in fruiting body development. Compared to the control group, damaged mycelia treated with HRW regenerated earlier and showed significantly enhanced fruiting body production. Antioxidant capacity increased significantly in damaged mycelia after HRW treatment, as indicated by higher antioxidant enzyme activities and antioxidant contents; the levels of reactive oxygen species (ROS) and malondialdehyde (MDA) were also reduced at the mycelial regeneration stage after treatment with HRW. Furthermore, genes involved in ROS, Ca2+, MAPK and oxylipin signaling pathways were up-regulated by HRW treatment. In addition, laccase and manganese peroxidase activities and mycelial biomass were higher after HRW treatment, suggesting that HRW might enhance the substrate-degradation rate to provide more carbon sources for fruiting body production.

N-n-Butyl Haloperidol Iodide, a Derivative of the Anti-psychotic Haloperidol, Antagonizes Hypoxia/Reoxygenation Injury by Inhibiting an Egr-1/ROS Positive Feedback Loop in H9c2 Cells.

Early growth response-1 (Egr-1), a transcription factor which often underlies the molecular basis of myocardial ischemia/reperfusion (I/R) injury, and oxidative stress, is key to myocardial I/R injury. Silent information regulator of transcription 1(SIRT1) not only interacts with and is inhibited by Egr-1, but also downregulates reactive oxygen species (ROS) via the Forkhead box O1(FOXO1)/manganese superoxide dismutase (Mn-SOD) signaling pathway. N-n-butyl haloperidol iodide (F2), a new patented compound, protects the myocardium against myocardial I/R injury in various animal I/R models in vivo and various heart-derived cell hypoxia/reoxygenation (H/R) models in vitro. In addition, F2 can regulate the abnormal ROS/Egr-1 signaling pathway in cardiac microvascular endothelial cells (CMECs) and H9c2 cells after H/R. We studied whether there is an inverse Egr-1/ROS signaling pathway in H9c2 cells and whether the SIRT1/FOXO1/Mn-SOD signaling pathway mediates this. We verified a ROS/Egr-1 signaling loop in H9c2 cells during H/R and that F2 protects against myocardial H/R injury by affecting SIRT1-related signaling pathways. Knockdown of Egr-1, by siRNA interference, reduced ROS generation, and alleviated oxidative stress injury induced by H/R, as shown by upregulated mitochondrial membrane potential, increased glutathione peroxidase (GSH-px) and total SOD anti-oxidative enzyme activity, and downregulated MDA. Decreases in FOXO1 protein expression and Mn-SOD activity occurred after H/R, but could be blocked by Egr-1 siRNA. F2 treatment attenuated H/R-induced Egr-1 expression, ROS generation and other forms of oxidative stress injury such as MDA, and prevented H/R-induced decreases in FOXO1 and Mn-SOD activity. Nuclear co-localization between Egr-1 and SIRT1 was increased by H/R and decreased by either Egr-1 siRNA or F2. Therefore, our results suggest that Egr-1 inhibits the SIRT1/FOXO1/Mn-SOD antioxidant signaling pathway to increase ROS and perpetuate I/R injury. F2 inhibits induction of Egr-1 by H/R, thereby activating SIRT1/FOXO1/Mn-SOD antioxidant signaling and decreasing H/R-induced ROS, demonstrating an important mechanism by which F2 protects against myocardial H/R injury.