Reactive Oxygen Species Accumulation In Cells Research Articles

Ginseng Stem-and-Leaf Saponins Mitigate Chlorpyrifos-Evoked Intestinal Toxicity In Vivo and In Vitro: Oxidative Stress, Inflammatory Response and Apoptosis.

In recent years, the phenomenon of acute poisoning and organ damage caused by organophosphorus pesticides (OPs) has been a frequent occurrence. Chlorpyrifos (CPF) is one of the most widely used organophosphorus pesticides. The main active components of ginseng stems and leaves are total ginseng stem-and-leaf saponins (GSLSs), which have various biological effects, including anti-inflammatory, antioxidant and anti-tumor activities. We speculate that these could have great potential in the treatment of severe diseases and the relief of organophosphorus-pesticide-induced side effects; however, their mechanism of action is still unknown. At present, our work aims to evaluate the effects of GSLSs on the antioxidation of CPF in vivo and in vitro and their potential pharmacological mechanisms. Mice treated with CPF (5 mg/kg) showed severe intestinal mucosal injury, an elevated diamine oxidase (DAO) index, the decreased expression of occlusive protein-1 (ZO-1) and occlusive protein, an impaired intestinal mucosal oxidation system and intestinal villi relaxation. In addition, chlorpyrifos exposure significantly increased the contents of the inflammatory factor TNF-α and the oxidative-stress-related indicators superoxide dismutase (SOD), catalase (CAT), glutathione SH (GSH), glutathione peroxidase (GSH-PX), reactive oxygen species (ROS) and total antioxidant capacity (T-AOC); elevated the level of lipid peroxide malondialdehyde (MDA); reversed the expression of Bax and caspase; and activated NF-κB-related proteins. Interestingly, GSLS supplementation at doses of 100 and 200 mg/kg significantly reversed these changes after treatment. Similar results were observed in cultured RAW264.7 cells. Using flow cytometry, Hoechst staining showed that GSLSs (30 μg/mL, 60 μg/mL) could improve the cell injury and apoptosis caused by CPF and reduce the accumulation of ROS in cells. In conclusion, GSLSs play a protective role against CPF-induced enterotoxicity by inhibiting NF-κB-mediated apoptosis and alleviating oxidative stress and inflammation.

L-Ascorbic Acid 2-Phosphate Attenuates Methylmercury-Induced Apoptosis by Inhibiting Reactive Oxygen Species Accumulation and DNA Damage in Human SH-SY5Y Cells

Methylmercury (MeHg) is a toxin that causes severe neuronal oxidative damage. As vitamin C is an antioxidant well-known to protect neurons from oxidative damage, our goal was to elucidate its protective mechanism against MeHg-induced oxidative stress in human neuroblastomas (SHSY5Y). We treated cells with MeHg, L-ascorbic acid 2-phosphate (AA2P), or both, and used MTT, flow cytometry, and Western blot analyses to assess cell damage. We found that MeHg significantly decreased the survival rate of SH-SY5Y cells in a time- and dose-dependent manner, increased apoptosis, downregulated PAR and PARP1 expression, and upregulated AIF, Cyto C, and cleaved Caspase-3 expression. A time course study showed that MeHg increased reactive oxygen species (ROS) accumulation; enhanced apoptosis; increased DNA damage; upregulated expression ofγH2A.X, KU70, 67 and 57 kDa AIF, CytoC, and cleaved Caspase-3; and downregulated expression of 116 kDa PARP1, PAR, BRAC1, and Rad51. Supplementation with AA2P significantly increased cell viability and decreased intrinsic ROS accumulation. It also reduced ROS accumulation in cells treated with MeHg and decreased MeHg-induced apoptosis. Furthermore, AA2P conversely regulated gene expression compared to MeHg. Collectively, we demonstrate that AA2P attenuates MeHg-induced apoptosis by alleviating ROS-mediated DNA damage and is a potential treatment for MeHg neurotoxicity.

Cell-Free Supernatant of Bacillus subtilis Reduces Kiwifruit Rot Caused by Botryosphaeria dothidea through Inducing Oxidative Stress in the Pathogen.

Biological control of postharvest diseases has been proven to be an effective alternative to chemical control. As an environmentally friendly biocontrol agent, Bacillus subtilis has been widely applied. This study explores its application in kiwifruit soft rot and reveals the corresponding mechanisms. Treatment with cell-free supernatant (CFS) of Bacillus subtilis BS-1 significantly inhibits the mycelial growth of the pathogen Botryosphaeria dothidea and attenuates the pathogenicity on kiwifruit in a concentration-dependent manner. In particular, mycelial growth diameter was only 21% of the control after 3 days of treatment with 5% CFS. CFS caused swelling and breakage of the hyphae of B. dothidea observed by scanning electron microscopy, resulting in the leakage of nucleic acid and soluble protein and the loss of ergosterol content. Further analysis demonstrated that CFS significantly induces the expression of Nox genes associated with reactive oxygen species (ROS) production by 1.9-2.7-fold, leading to a considerable accumulation of ROS in cells and causing mycelial cell death. Our findings demonstrate that the biocontrol effect of B. subtilis BS-1 CFS on B. dothidea is realized by inducing oxidative damage to the mycelia cell.

Causative links between ER stress and oxidative damage in a yeast model of human N88S seipinopathy

Seipin is encoded by the gene Berardinelli-Seip congenital lipodystrophy type 2 (BSCL2) and FLD1/SEI1 in yeast. The gain-of-function N88S mutation in the BSCL2 gene was identified in a cohort of autosomal dominant motor neuron diseases (MNDs) collectively known as seipinopathies. Previous work has shown that this mutation disrupts N-glycosylation, leading to the formation of inclusion bodies (IBs) and contributing to severe Endoplasmic Reticulum (ER) stress and cell death. In this work, we established a humanized yeast model of N88S seipinopathy that recapitulated the formation of IBs and activation of the unfolded protein response (UPR) observed in mammalian systems. Autophagy and the Hrd1-mediated endoplasmic reticulum-associated degradation (ERAD) were fully functional in cells expressing mutant homomers and WT-mutant heteromers of seipin, discarding the possibility that mutant seipin accumulate due to impaired protein quality control systems. Importantly, the N88S seipin form IBs that appear to induce changes in ER morphology, in association with Kar2 chaperone and the Hsp104 disaggregase.For the first time, we have determined that N88S homo-oligomers expressing cells present reduced viability, decreased antioxidant activity and increased oxidative damage associated with loss of mitochondrial membrane potential, higher reactive oxygen species (ROS) levels and lipid peroxidation. This was correlated with the activation of oxidative stress sensor Yap1. Moreover, activation of ERAD and UPR quality control mechanisms were essential for proper cell growth, and crucial to prevent excessive accumulation of ROS in cells expressing N88S homomers solely. Overall, this study provides new insights into the molecular underpinnings of these rare diseases and offers novel targets for potential pharmacological intervention.

Research progress on the role of nuclear factor erythroid 2-related factor 2 in ferroptosis of sepsis

Sepsis is a life-threatening organ dysfunction caused by the disorder of the body's response to infection, and is one of the main causes of death in critically ill patients. Ferroptosis is a kind of iron dependent cell death, characterized by intracellular reactive oxygen species (ROS) accumulation. Sepsis can cause a substantial accumulation of ROS in cells. The transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) is a key regulator of antioxidant and plays a critical protective role in sepsis induced ferroptosis by regulating the expression of proteins related to the ferroptosis pathway. Current studies have found that activation of Nrf2 has a protective effect on ferroptosis induced by sepsis. In this paper, we summarized the regulation mechanism of Nrf2 in ferroptosis, in order to provide references for the treatment of sepsis.

Isobavachalcone disrupts mitochondrial respiration and induces cytotoxicity through ROS accumulation and Akt suppression

Isobavachalcone (IBC) is one of the flavonoid components in Fructus Psoraleae, and has been found multiple pharmacological effects. However, the hepatotoxicity of IBC has been overlooked and not been carefully studied. We aim to find out the cytotoxicity of IBC on HepG2 cells, and explore the underlying mechanisms. HepG2 cells were treated with IBC for 24 h, then MTT assay and LDH assay were used to detect the cell viability. The apoptosis and reactive oxygen species (ROS) production were reflected by the flow cytometry. Using Seahorse Analyzer, we measured the mitochondrial respiratory capacity. The expression of oxidative stress and mitochondrial apoptosis-related proteins were determined by Western blot. The results showed that IBC induced the cell death and apoptosis of HepG2 cells. IBC initiated the accumulation of ROS in cells and impaired the mitochondrial function, triggered apoptosis and suppressed the phosphorylation of Akt. Additionally, scavenging ROS by the antioxidant N-acetyl-l-cysteine (NAC) reduced IBC-induced mitochondria damage and increased Akt phosphorylation. Taken together, IBC caused mitochondrial damage and induced hepatotoxicity by ROS accumulation and Akt suppression. Targeting oxidative stress and depressing mitochondrial damage may provide a theoretical basis for the treatment and prevention of IBC-induced hepatotoxicity in clinic.

Effects of mesenchymal stem cell-derived exosomes on oxidative stress responses in skin cells.

The mechanism by which reactive oxygen species (ROS) produced by oxidative stress promote cellular senescence has been studied in detail. This study aimed to verify the preventive or therapeutic effects of mesenchymal stem cell-derived exosomes (MSC-Ex) on the production of ROS induced by oxidative stress in human skin fibroblasts and clarify the mechanisms that promote cellular senescence. In a system where H2O2 was applied to skin fibroblasts, we assessed the effects of the application of MSC-Ex before and after oxidative stress and measured the fluctuations in several signaling molecules involved in subsequent intracellular stress responses. Exosomes were isolated from MSCs (MSC-Ex) and normal human dermal fibroblasts (NHDFs, NHDF-Ex) before and after exposure to H2O2. NHDFs were treated with exosomes before and after exposure to H2O2. mRNA expression (aquaporin-1 and aquaporin-3) and hyaluronan secretion associated with skin moisturization were reduced by H2O2 treatment, whereas MSC-Ex reversed these effects. The cellular senescence induced by H2O2 was also reproduced in fibroblasts. Specifically, the downregulation of SIRT1 led to increased acetylated p53 expression over time, which induced the expression of p21, a downstream molecule of p53, and arrested the cell cycle, leading to cell senescence. MSC-Ex enhanced these signal transduction systems. MSC-Ex was also effective at blocking the increase of β-galactosidase activity and accumulation of ROS in cells. This effect was stronger than that of NHDF-Ex. MSC-Ex were found to act defensively against epidermal and cellular senescence induced by oxidative stress.

Membrane-Bound Transcriptional Activator NTL1 from Rapeseed Positively Modulates Leaf Senescence through Targeting Genes Involved in Reactive Oxygen Species Production and Programmed Cell Death.

Leaf senescence is the last stage of leaf development and is determined by various environmental and endogenous signals. Leaf senescence can determine plant productivity and fitness. Transcription factors (TFs) with the transmembrane domain constitute a special group of regulatory proteins that can translocate from the membrane system into nuclei to exert the transcriptional function upon endogenous or exogenous stimuli. Reactive oxygen species (ROSs) play an important role in numerous processes throughout the life cycle of plants including leaf senescence. Leaf senescence is characterized by massive programmed cell death (PCD) and is a type of developmental PCD. The transcriptional regulatory relationships between membrane-bound TFs and leaf senescence remain largely uncharacterized, especially in rapeseed (Brassica napus L.), an important oil crop. Here, we show that BnaNTL1 is a membrane-bound NAC (NAM, ATAF, and CUC) TF, which is predominantly expressed in senescent leaves. Expression of BnaNTL1ΔTM, a form of BnaNTL1 devoid of the transmembrane domain, can induce serious HR-like cell death symptoms and ROS accumulation in cells. Plants overexpressing BnaNTL1ΔTM show earlier leaf senescence compared with the control, accompanied by chlorophyll degradation and electrolyte leakage. Genes involved in ROS production (RbohD), PCD (VPEs and CEP1), and leaf senescence (BFN1) are significantly induced and activated by BnaNTL1ΔTM according to the quantitative reverse transcription PCR (qRT-PCR) analysis and dual luciferase reporter (Dual-LUC) assay. Moreover, electrophoretic mobility shift assay revealed that BnaNTL1 directly bound to the NTLBS elements in promoters of RbohD, γVPE, and BFN1. In conclusion, these results demonstrate that BnaNTL1 positively modulates ROS production and HR-like cell death to induce leaf senescence.

Mitochondria at the crossroads of ATM-mediated stress signaling and regulation of reactive oxygen species

The Ataxia-telangiectasia mutated (ATM) kinase responds to DNA double-strand breaks and other forms of cellular stress, including reactive oxygen species (ROS). Recent work in the field has uncovered links between mitochondrial ROS and ATM activation, suggesting that ATM acts as a sensor for mitochondrial derived ROS and regulates ROS accumulation in cells through this pathway. In addition, characterization of cells from Ataxia-telangiectasia patients as well as ATM-deficient mice and cell models suggest a role for ATM in modulating mitochondrial gene expression and function. Here we review ROS responses related to ATM function, recent evidence for ATM roles in mitochondrial maintenance and turnover, and the relationship between ATM and regulation of protein homeostasis.

Candida albicans infection disturbs the redox homeostasis system and induces reactive oxygen species accumulation for epithelial cell death.

Candida albicans is a common pathogenic fungus with high mortality in immunocompromised patients. However, the mechanism by which C. albicans invades host epithelial cells and causes serious tissue damage remains to be further investigated. In this study, we established the C. albicans-293T renal epithelial cell interaction model to investigate the mechanism of epithelial infection by this pathogen. It was found that C. albicans infection causes severe cell death and reactive oxygen species (ROS) accumulation in epithelial cells. Further investigations revealed that C. albicans infection might up-regulate expression of nicotinamide adenine dinucleotide phosphate (NAPDH) oxidase (NOX), inhibit the activity of the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT), and suppress the p38-Nrf2-heme oxygenase-1 (HO-1) pathway which plays an important role in the elimination of intracellular ROS. Furthermore, epithelial cell death caused by the fungal infection could be strikingly alleviated by addition of the antioxidant agent glutathione, indicating the critical role of ROS accumulation in cell death caused by the fungus. This study revealed that disturbance of the redox homeostasis system and ROS accumulation in epithelial cells is involved in cell death caused by C. albicans infection, which sheds light on the application of antioxidants in the suppression of tissue damage caused by fungal infection.

Production, Signaling, and Scavenging Mechanisms of Reactive Oxygen Species in Fruit-Pathogen Interactions.

Reactive oxygen species (ROS) play a dual role in fruit–pathogen interaction, which largely depends on their different levels in cells. Fruit recognition of a pathogen immediately triggers an oxidative burst that is considered an integral part of the fruit defense response. ROS are also necessary for the virulence of pathogenic fungi. However, the accumulation of ROS in cells causes molecular damage and finally leads to cell death. In this review, on the basis of data regarding ROS production and the scavenging systems determining ROS homeostasis, we focus on the role of ROS in fruit defense reactions against pathogens and in fungi pathogenicity during fruit–pathogen interaction.

SAT-175 (-)-Epicatechin Modulates Cellular Signaling and Mitochondrial Redox in Endothelium

Diabetes mellitus affects 451 million people worldwide, and people with diabetes are 3-5 times more likely to develop cardiovascular disease. In vascular tissue, mitochondrial function is important for vasodilation and arterial stiffness, both of which are abnormal in diabetes. Diabetes-mediated generation of excess reactive oxygen species (ROS) may be contributing to this problem. We have identified (-)-epicatechin (EPICAT), a plant compound and known vasodilator, as a potential therapy. We hypothesized that mitochondrial ROS accumulation in cells treated with high glucose (HG) or antimycin A (AA, a compound targeting complex III) could be diminished by EPICAT. We further hypothesized that reduction of ROS would correlate with improved mitochondrial dynamics and cellular signaling. To test this hypothesis, we employed human umbilical vein endothelial cells (HUVEC) treated with HG, AA, and/or 0.1 or 1.0 µM of EPICAT, and measured mitochondrial and cellular superoxide, mitochondrial dynamics, and cellular signaling upstream of mitochondrial function. AA significantly increased mitochondrial width (p=0.012) and decreased mitochondrial length (p=0.0001), but we observed no impact of EPICAT. We measured superoxide production by electron paramagnetic resonance spectroscopy using two spin probes specific to mitochondrial (Mito-TEMPO-H) and total cell (CMH) superoxide. No impact of HG treatment was detected in the total cell superoxide; however, an increase in mitochondrial superoxide was measured in cells treated with HG as compared to control (0.42 µM superoxide vs. 0.31 µM superoxide, respectively). We found that both concentrations of EPICAT significantly attenuated mitochondrial superoxide production when treated with HG (HG alone=0.44 µM superoxide, HG + 0.1 µM EPICAT=0.34 µM superoxide, HG + 1.0 µM EPICAT= 0.34 µM superoxide, p=0.02 EPICAT effect), but not with AA treatment. We found that in combination with HG, 0.1 µM EPICAT significantly increased eNOS expression (p<0.05). At 1.0 µM, EPICAT also increased peNOS expression (p<0.05) and attenuated a decrease in pAMPK (p<0.05) in response to HG. EPICAT at both concentrations significantly increased mitochondrial complex II expression (p<0.05 for both). In summary, HG-induced mitochondrial ROS is responsive to EPICAT, whereas AA-induced ROS is not, suggesting that EPICAT is useful in mitigating moderate ROS concentrations and may be modulating mitochondrial activity upstream of complex III. Our data further illustrate that EPICAT may be a tool to modulate both cellular and mitochondrial glucose toxicity through the regulation of AMPK and eNOS, upstream of mitochondrial activity, as well as bolstering endogenous antioxidant defenses.

Visualisation of reactive oxygen species during stress of spearmint (Mentha spicata L.)

The present study is the first to describe the detection of Reactive Oxygen Species (ROS) in spearmint (Mentha spicata L.) grown under nutrient stress conditions through 3, 30-diaminobenzidine (DAB) and nitro blue tetrazolium chloride (NBT) histochemical methods. Spearmint cuttings grown under manganese and salt conditions showed toxicity and stunted growth after 10 and 20 days of the stress treatments (> 2.5 mM for the manganese and >100 mM for the saline stress). These abiotic stresses induced the production of ROS in the leaf tissue of the spearmint. Accumulation of hydrogen peroxide was characterised as brown spots by DAB polymerisation which was noticed on leaf tissues from the plants grown under 2.5 and 5 mM concentrations of manganese as well as 300 mM concentration of salt. Furthermore, accumulation of superoxide anion was also characterised as blue pigments based upon the ability of cells to reduce NBT. Level of the secondary metabolite menthol was also significantly increased in response to the ROS production. Our study confirmed the validity of use of DAB and NBT stains in elucidating ROS accumulation in cells of spearmint, the important medical plant under nutrient stress conditions.

Inhibition of ROS-mediated activation Src-MAPK/AKT signaling by orientin alleviates H2O2-induced apoptosis in PC12 cells.

PurposeReactive oxygen species (ROS) are considered a direct cause of neurodegenerative diseases (NDDs). Drugs developed to target ROS are effective for the treatment of NDDs. Orientin is a pyrone glucoside extracted from Polygonum orientale, and it exhibits many pharmacological activities. In this study, we aimed to determine whether orientin could relieve hydrogen peroxide (H2O2)-induced neuronal apoptosis and to investigate the specific target of orientin.Materials and methodsIn this study, the neuroprotective effect and its possible mechanisms of orientin in mouse pheochromocytoma cell line (PC12) cells stimulated by H2O2, establishing an oxidative stress model, were investigated. And we further tested the role of ROS in the neuroprotective effects of orientin.ResultsOrientin (5–100 µg/mL) did not cause toxicity in PC12 cells but significantly decreased H2O2-induced reduction in PC12 cell viability, cell apoptosis rates, and nuclear condensation. It also inhibited the activation of caspase-3 and degradation of poly(ADP-ribose) polymerase (PARP). Under the stimulation of H2O2, MAPKs (ERK, JNK, and p38), AKT, and Src signaling proteins in PC12 cells were activated in a time-dependent manner. The application of inhibitors that were specific for MAPKs, AKT, and Src effectively alleviated H2O2-induced cell apoptosis. In addition, the Src inhibitor decreased the activation of MAPKs and AKT signaling. More importantly, orientin effectively decreased H2O2-induced phosphorylation of MAPKs, AKT, and Src signaling proteins. Finally, we confirmed that orientin effectively inhibited H2O2-induced accumulation of ROS in cells. In addition, ROS inhibitors blocked the Src-MAPKs/AKT signaling pathway-dependent cell apoptosis stimulated by H2O2.ConclusionThese results indicate that alleviation of H2O2-induced cell apoptosis by orientin is Src-MAPKs/AKT dependent. Overall, our study confirms that orientin alleviates H2O2-induced cell apoptosis by inhibiting the ROS-mediated activation of Src-MAPKs/AKT signaling.

Highly sensitive platinum nanoparticles-embedded porous graphene sensor for monitoring ROS from living cells upon oxidative stress

Real-time monitoring reactive oxygen species (ROS) released from living cells is important in both physiological and pathological contexts. The excessive amount of ROS accumulation in cells could lead to a series of cell damage and cause aging and disease. Here we present design, fabrication, and successful testing of a highly sensitive electrochemical hydrogen peroxide sensor based on a three-dimensional (3D) platinum nanoparticles (PtNPs) decorated porous graphene composite. Scanning electron microscopy (SEM) investigations indicate that PtNPs were embedded into porous graphene (PGN), something that was rarely reported. With the help of the excellent catalytic activity of PtNPs and unique porous structure in combination with inherent properties of graphene, the PtNPs/PGN based sensor presents efficient electrochemical performance for H2O2 sensing with a detection limit of 0.02 nM, the lowest detection limit achieved in nonenzymatic electrochemical sensors so far, which guarantees the possibility of sensitive and reliable detection of H2O2 release from living cells. This work opens a new avenue for direct preparation of metal nanoparticle-embedded porous graphene composite. More importantly, the presented sensors can be successfully used for monitoring changes of H2O2 levels upon different stimuli and collecting kinetic information on cellular ROS release, which provides more opportunities to study its cellular biochemistry.

Effects of 5-hydroxy-4'-nitro-7-propionyloxy-genistein on inhibiting proliferation and invasion via activating reactive oxygen species in human ovarian cancer A2780/DDP cells.

5-hydroxy-4'-nitro-7-propionyloxy-genistein (HNPG), a novel synthetic isoflavone derivative, was demonstrated to possess antitumor activity in gastric cancer and breast cancer in vitro, but its antitumor effect and mechanism in ovarian cancer has not been characterized. The aim of the present study was to investigate the effects of HNPG on inhibiting the proliferation and invasion in human ovarian cancer A2780 cell lines of cisplatin resistance (A2780/DDP) and elucidate its underlying molecular mechanism. The results indicated that HNPG presented with marked antitumor activity against A2780/DDP cells in vitro, significantly inhibited the rates of proliferation, clone formation, invasion and metastasis, and markedly induced apoptosis in dose- and time-dependent manner. Simultaneously, levels of reactive oxygen species (ROS) were increased and mitochondrial membrane potential was decreased. In addition, Bcl-2 expression was downregulated, Bax expression was upregulated, and the ratio of Bcl-2/Bax was decreased. Concurrently, levels of Cyt-C were markedly enhanced and the caspase cascade was triggered. Taken together, the results suggested that HNPG exerted anticancer effects through promoting ROS accumulation in cells, triggering mitochondrial apoptotic pathways and ultimately resulting in cells apoptosis. Therefore, HNPG serves as a potential candidate in the chemoprevention and/or treatment of cisplatin-resistant human ovarian cancer.

Protein kinase CK2 regulates redox homeostasis through NF-κB and Bcl-xL in cardiomyoblasts.

Oxygen consumption is particularly elevated in cardiac cells as they are equipped with a large number of mitochondria and high levels of respiratory chain components. Consequently, production of reactive oxygen species (ROS) is tightly controlled as an imbalance in redox reactions can lead to irreversible cellular damage. siRNA-mediated down-regulation of protein kinase CK2has been implicated in the accumulation of ROS in cells. The present study was undertaken in order to investigate the role of CK2 in redox homeostasis in cardiomyoblasts. We found that inhibition or silencing of CK2 causes elevated levels of ROS, notably superoxide radical, and this is accompanied by suppression of NF-κB transcriptional activity and mitochondrial dysfunction. We show that CK2 regulates the expression of manganese superoxide dismutase, the enzyme catalyzing the dismutation of superoxide, in cancer cells but not in cardiomyoblasts. Furthermore, we report evidence that impaired expression of CK2 results in destabilization of the Bcl-2 mammalian homolog Bcl-xL, which is known to stabilize the mitochondrial membrane potential, through a mechanism involving disruption of the chaperone function of heat shock protein 90. Analysis of differential mRNA expression related to oxidative stress revealed that CK2 silencing caused a statistically significant deregulation of four genes associated with the oxidative damage, i.e., Fmo2, Ptgs1, Dhcr24, and Ptgs2. Overall, the results reported here are consistent with the notion that CK2 plays a role in conferring protection against oxidative stress by positively regulating pro-survival signaling molecules and the protein folding machinery in cardiomyoblasts.

Furfural induces reactive oxygen species accumulation and cellular damage in Saccharomyces cerevisiae

BackgroundBiofuels offer a viable alternative to petroleum-based fuel. However, current methods are not sufficient and the technology required in order to use lignocellulosic biomass as a fermentation substrate faces several challenges. One challenge is the need for a robust fermentative microorganism that can tolerate the inhibitors present during lignocellulosic fermentation. These inhibitors include the furan aldehyde, furfural, which is released as a byproduct of pentose dehydration during the weak acid pretreatment of lignocellulose. In order to survive in the presence of furfural, yeast cells need not only to reduce furfural to the less toxic furan methanol, but also to protect themselves and repair any damage caused by the furfural. Since furfural tolerance in yeast requires a functional pentose phosphate pathway (PPP), and the PPP is associated with reactive oxygen species (ROS) tolerance, we decided to investigate whether or not furfural induces ROS and its related cellular damage in yeast.ResultsWe demonstrated that furfural induces the accumulation of ROS in Saccharomyces cerevisiae. In addition, furfural was shown to cause cellular damage that is consistent with ROS accumulation in cells which includes damage to mitochondria and vacuole membranes, the actin cytoskeleton and nuclear chromatin. The furfural-induced damage is less severe when yeast are grown in a furfural concentration (25 mM) that allows for eventual growth after an extended lag compared to a concentration of furfural (50 mM) that prevents growth.ConclusionThese data suggest that when yeast cells encounter the inhibitor furfural, they not only need to reduce furfural into furan methanol but also to protect themselves from the cellular effects of furfural and repair any damage caused. The reduced cellular damage seen at 25 mM furfural compared to 50 mM furfural may be linked to the observation that at 25 mM furfural yeast were able to exit the furfural-induced lag phase and resume growth. Understanding the cellular effects of furfural will help direct future strain development to engineer strains capable of tolerating or remediating ROS and the effects of ROS.

Compound Deficiency of Nrf2 and Selenoproteins in Hematopoietic Cells Leads to Severe Defects in Erythroid and Lymphoid Lineage Development.

Abstract 1993Poster Board I-1015Precise regulation of reactive oxygen species (ROS) level is essential for normal cellular homeostasis. Defect of ROS scavenging system results in excess accumulation of ROS in cells, leading to the cellular aging and senescence. Nrf2 (NF-E2-related factor 2) is a basic leucine zipper-type transcription factor, which regulates expression of a set of genes related to the ROS scavenging and detoxification. While accumulating lines of evidence support the significance of Nrf2 for the cellular protection in many types of cells, Nrf2-deficient mice live out their natural life span under the homeostatic condition, and show no significant hematological abnormality except for anemia with aging. We previously found that the Nrf2 activity rose in the macrophages and liver cells derived from conditional knockout (CKO) mice of the selenocystein tRNA (Trsp) gene. The Trsp gene is essential for production of selenoproteins, including glutathione peroxidase and thioredoxin reductase. Thus, there are two prevalent ROS scavenging systems based on different molecular mechanisms; Nrf2 and selenoproteins seemingly act compensatory and cooperatively for maintenance of hematopoietic homeostasis. To explore the roles Nrf2 and selenoproteins play in hematopoietic cells, we conducted conditional knockout of the Trsp gene by crossing Trsp-floxed mice with the interferon-inducible Mx1-Cre transgenic mice in combination with Nrf2 gene knockout (KO) in germline. The Trsp-CKO mice in the background of Nrf2 wild type (Trsp single KO mice) showed thymic atrophy with massive reduction of CD4/CD8 double-positive cells in thymus. This T-lymphocytic phenotype was not changed in the Trsp-CKO mice under the circumstance of Nrf2-null condition (Trsp:Nrf2 double KO mice), suggesting that selenoproteins were prerequisite for the T-cell development. The Trsp single KO mice suffered from mild anemia with increased number of erythroid progenitors in bone marrow and spleen, and importantly this erythroid phenotype was dramatically exacerbated in the Trsp:Nrf2 double KO mice. A large number of poikilocytes and teardrop-shaped cells were observed in the blood smear of the Trsp:Nrf2 double KO mice, whereas these deformed red blood cells were vaguely found in the Trsp single KO mice. Intracellular ROS level was significantly elevated in erythroid progenitors recovered from the Trsp:Nrf2 double KO mice, although that of the Trsp single KO mice were maintained within normal level, indicating that Nrf2 compensates for the defect of ROS scavenging function caused by the loss of selenoproteins in erythroid cells. These results thus demonstrate for the first time that the ROS scavenging conducted by Nrf2 and selenoproteins is essential for the homeostatic maintenance in erythroid and lymphoid cells in a lineage-specific manner. Disclosures:No relevant conflicts of interest to declare.