Free radical biology & medicine最新文献

{"title":"On the use of L-012, a luminol-based chemiluminescent probe, for detecting superoxide and identifying inhibitors of NADPH oxidase: a reevaluation.","authors":"Jacek Zielonka,&nbsp;J David Lambeth,&nbsp;Balaraman Kalyanaraman","doi":"10.1016/j.freeradbiomed.2013.09.017","DOIUrl":"https://doi.org/10.1016/j.freeradbiomed.2013.09.017","url":null,"abstract":"<p><p>L-012, a luminol-based chemiluminescent (CL) probe, is widely used in vitro and in vivo to detect NADPH oxidase (Nox)-derived superoxide (O2(*-)) and identify Nox inhibitors. Yet understanding of the free radical chemistry of the L-012 probe is still lacking. We report that peroxidase and H2O2 induce superoxide dismutase (SOD)-sensitive, L-012-derived CL in the presence of oxygen. O2(*-) alone does not react with L-012 to emit luminescence. Self-generated O2(*-) during oxidation of L-012 and luminol analogs artifactually induce CL inhibitable by SOD. These aspects make assays based on luminol analogs less than ideal for specific detection and identification of O2(*-) and NOX inhibitors.</p>","PeriodicalId":505743,"journal":{"name":"Free radical biology & medicine","volume":" ","pages":"1310-1314"},"PeriodicalIF":7.4,"publicationDate":"2013-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.freeradbiomed.2013.09.017","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"31771076","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Anthropometric indices and selenium status in British adults: the U.K. National Diet and Nutrition Survey.","authors":"Alexander Spina,&nbsp;Eliseo Guallar,&nbsp;Margaret P Rayman,&nbsp;William Tigbe,&nbsp;Ngianga-Bakwin Kandala,&nbsp;Saverio Stranges","doi":"10.1016/j.freeradbiomed.2013.09.025","DOIUrl":"https://doi.org/10.1016/j.freeradbiomed.2013.09.025","url":null,"abstract":"<p><p>Recent studies have raised concern over possible associations between high selenium (Se) status and excess adiposity, known to be linked to adverse cardiometabolic outcomes. Studies of Se status in relation to adiposity are scarce in the United Kingdom. This study examined cross-sectional associations of anthropometric indices with Se-status biomarkers in a nationally representative sample of 1045 (577 female, 468 male) British Caucasian adults ages 19-64 who participated in the 2000-2001 National Diet and Nutrition Survey. Median (first, third quartile) values for whole-blood glutathione peroxidase (GPx) activity and plasma and erythrocyte Se concentrations were 120.0 (103.0, 142.4) nmol mg Hb(-1) min(-1), 1.08 (0.98, 1.20) µmol/L, and 1.62 (1.38, 1.91) µmol/L, respectively. For males, values were 119.0 (100.0, 141.0) nmol mg Hb(-1) min(-1), 1.09 (0.99, 1.22) µmol/L, and 1.54 (1.34, 1.79) µmol/L, respectively; for females 121.0 (105.0, 145.0) nmol mg Hb(-1) min(-1), 1.07 (0.97, 1.18) µmol/L, and 1.71 (1.43, 1.99) µmol/L, respectively. Multivariate adjusted mean differences (95% CI) in whole-blood GPx between the highest (>30 kg/m(2)) and the lowest (<25 kg/m(2)) categories of body mass index and the highest (96.5-139.2 cm) and the lowest (52.2-78.1cm) quartiles of waist circumference (WC) were -7.9 (-13.2, -2.7) and -9.7 (-16.2, -3.2) nmol mg Hb(-1) min(-1), respectively. Difference (95% CI) in plasma Se between the third (87.5-96.4 cm) and the lowest quartiles of WC was -0.04 (-0.08, -0.03) µmol/L. Difference (95% CI) in red blood cell (RBC) Se between the highest (0.91-1.11) and the lowest (0.53-0.76) quartiles of waist-to-hip ratio (WHR) was 0.10 (0.00, 0.20) µmol/L. Similar results were observed in gender and menopausal-status subgroup analyses. The inverse association between plasma Se and WC and the positive association between RBC Se and WHR will need confirmation. The findings suggest associations between low whole-blood GPx activity and higher measures of general and central adiposity. Further experimental and randomized studies are needed to deduce the mechanisms and infer causality.</p>","PeriodicalId":505743,"journal":{"name":"Free radical biology & medicine","volume":" ","pages":"1315-1321"},"PeriodicalIF":7.4,"publicationDate":"2013-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.freeradbiomed.2013.09.025","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"31782988","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparative reactivity of the myeloperoxidase-derived oxidants hypochlorous acid and hypothiocyanous acid with human coronary artery endothelial cells.","authors":"Mitchell M Lloyd,&nbsp;Michael A Grima,&nbsp;Benjamin S Rayner,&nbsp;Katrina A Hadfield,&nbsp;Michael J Davies,&nbsp;Clare L Hawkins","doi":"10.1016/j.freeradbiomed.2013.10.007","DOIUrl":"https://doi.org/10.1016/j.freeradbiomed.2013.10.007","url":null,"abstract":"<p><p>In the immune response, hypohalous acids are generated by activated leukocytes via the release of myeloperoxidase and the formation of H2O2. Although these oxidants have important bactericidal properties, they have also been implicated in causing tissue damage in inflammatory diseases, including atherosclerosis. Hypochlorous acid (HOCl) and hypothiocyanous acid (HOSCN) are the major oxidants formed by myeloperoxidase under physiological conditions, with the ratio of these oxidants dependent on diet and smoking status. HOCl is highly reactive and causes marked cellular damage, but few data are available on the effects of HOSCN on mammalian cells. In this study, we have compared the actions of HOCl and HOSCN on human coronary artery endothelial cells (HCAEC). HOCl reacts rapidly with the cells, resulting in extensive cell death by both apoptosis and necrosis, with necrosis dominating at higher oxidant doses. In contrast, HOSCN is consumed more slowly, with cell death occurring only by apoptosis. Exposure of HCAEC to HOCl and HOSCN induces changes in mitochondrial membrane permeability, which, in the case of HOSCN, is associated with mitochondrial release of proapoptotic factors, including cytochrome c, apoptosis-inducing factor, and endonuclease G. With each oxidant, apoptosis appears to be caspase-independent, with the inactivation of caspases 3/7 observed, and pretreatment of the cells with the caspase inhibitor Z-VAD-fmk having no effect on the extent of cell death. Loss of cellular thiols, depletion of glutathione, and the inactivation of thiol-dependent enzymes, including glyceraldehyde-3-phosphate dehydrogenase, were seen with both oxidants, though to a much greater extent with HOCl. The ability of myeloperoxidase-derived oxidants to induce endothelial cell apoptosis may contribute to the formation of unstable lesions in atherosclerosis. The results with HOSCN may be particularly significant for smokers, who have elevated plasma levels of SCN(-), the precursor of this oxidant. </p>","PeriodicalId":505743,"journal":{"name":"Free radical biology & medicine","volume":" ","pages":"1352-1362"},"PeriodicalIF":7.4,"publicationDate":"2013-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.freeradbiomed.2013.10.007","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"31803532","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A biophysically based mathematical model for the catalytic mechanism of glutathione reductase.","authors":"Venkat R Pannala,&nbsp;Jason N Bazil,&nbsp;Amadou K S Camara,&nbsp;Ranjan K Dash","doi":"10.1016/j.freeradbiomed.2013.10.001","DOIUrl":"https://doi.org/10.1016/j.freeradbiomed.2013.10.001","url":null,"abstract":"<p><p>Glutathione reductase (GR) catalyzes the reduction of oxidized glutathione (GSSG) to reduced glutathione (GSH) using NADPH as the reducing cofactor, and thereby maintains a constant GSH level in the system. GSH scavenges superoxide (O2(*-)) and hydroxyl radicals (OH) nonenzymatically or by serving as an electron donor to several enzymes involved in reactive oxygen species (ROS) detoxification. In either case, GSH oxidizes to GSSG and is subsequently regenerated by the catalytic action of GR. Although the GR kinetic mechanism has been extensively studied under various experimental conditions with variable substrates and products, the catalytic mechanism has not been studied in terms of a mechanistic model that accounts for the effects of the substrates and products on the reaction kinetics. The aim of this study is therefore to develop a comprehensive mathematical model for the catalytic mechanism of GR. We use available experimental data on GR kinetics from various species/sources to develop the mathematical model and estimate the associated model parameters. The model simulations are consistent with the experimental observation that GR operates via both ping-pong and sequential branching mechanisms based on relevant concentrations of its reaction substrate GSSG. Furthermore, we show the observed pH-dependent substrate inhibition of GR activity by GSSG and bimodal behavior of GR activity with pH. The model presents a unique opportunity to understand the effects of products on the kinetics of GR. The model simulations show that under physiological conditions, where both substrates and products are present, the flux distribution depends on the concentrations of both GSSG and NADP(+), with ping-pong flux operating at low levels and sequential flux dominating at higher levels. The kinetic model of GR may serve as a key module for the development of integrated models for ROS-scavenging systems to understand protection of cells under normal and oxidative stress conditions.</p>","PeriodicalId":505743,"journal":{"name":"Free radical biology & medicine","volume":" ","pages":"1385-1397"},"PeriodicalIF":7.4,"publicationDate":"2013-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.freeradbiomed.2013.10.001","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"31803216","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fibrogenic actions of acetaldehyde are β-catenin dependent but Wingless independent: a critical role of nucleoredoxin and reactive oxygen species in human hepatic stellate cells.","authors":"Jaime Arellanes-Robledo,&nbsp;Karina Reyes-Gordillo,&nbsp;Ruchi Shah,&nbsp;José Alfredo Domínguez-Rosales,&nbsp;Zamira Helena Hernández-Nazara,&nbsp;Francesco Ramirez,&nbsp;Marcos Rojkind,&nbsp;M Raj Lakshman","doi":"10.1016/j.freeradbiomed.2013.07.017","DOIUrl":"https://doi.org/10.1016/j.freeradbiomed.2013.07.017","url":null,"abstract":"<p><p>We investigated whether the fibrogenic actions of acetaldehyde, the immediate oxidation product of ethanol, are mediated via Wingless (WNT) and/or β-catenin pathways in human hepatic stellate cells (HSC). First, we show that both β-catenin small inhibitory RNA and a dominant negative-MYC expression vector markedly down-regulated the expressions of fibrogenic genes in freshly isolated HSC. We further show that acetaldehyde up-regulated platelet-derived growth factor receptor beta mRNA and protein expressions ranging from 4.0- to 7.2-fold (P<0.001). Acetaldehyde induced MYC and collagen type-1 alpha-2 mRNA and protein expressions were WNT independent because DKK1, an antagonist of the canonical WNT/β-catenin pathway, completely failed to block these inductions. Acetaldehyde increased phospho-glycogen synthase kinase-3 beta (GSK3B) protein by 31% (P<0.01), whereas phospho-β-catenin protein decreased by 50% (P ≤ 0.01). Significantly, in contrast to 43% (P<0.01) inhibition of β-catenin nuclear translocation in nucleoredoxin (NXN)-overexpressed HSC, acetaldehyde profoundly stimulated β-catenin nuclear translocation by 51%, (P<0.01). Acetaldehyde also increased the cellular reactive oxygen species level 2-fold (P<0.001) with a concomitant 2-fold (P<0.001) increase in 4-hydroxynonenal adducts. Conversely, there was a 44% decrease (P<0.001) in glutathione levels with a concomitant 76% (P<0.001) decrease in the level of NXN/ disheveled (DVL) complex. Based on these findings, we conclude that actions of acetaldehyde are mediated by a mechanism that inactivates NXN by releasing DVL, leading to the inactivation of GSK3B, and thereby blocks β-catenin phosphorylation and degradation. Thus, the stabilized β-catenin translocates to the nucleus where it up-regulates the fibrogenic pathway genes. This novel mechanism of action of acetaldehyde has the potential for therapeutic interventions in liver fibrosis induced by alcohol.</p>","PeriodicalId":505743,"journal":{"name":"Free radical biology & medicine","volume":" ","pages":"1487-1496"},"PeriodicalIF":7.4,"publicationDate":"2013-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.freeradbiomed.2013.07.017","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"31602584","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mitochondrial glutathione depletion reveals a novel role for the pyruvate dehydrogenase complex as a key H2O2-emitting source under conditions of nutrient overload.","authors":"Kelsey H Fisher-Wellman,&nbsp;Laura A A Gilliam,&nbsp;Chien-Te Lin,&nbsp;Brook L Cathey,&nbsp;Daniel S Lark,&nbsp;P Darrell Neufer","doi":"10.1016/j.freeradbiomed.2013.09.008","DOIUrl":"https://doi.org/10.1016/j.freeradbiomed.2013.09.008","url":null,"abstract":"<p><p>Once regarded as a \"by-product\" of aerobic metabolism, the production of superoxide/H2O2 is now understood to be a highly specialized and extensively regulated process responsible for exerting control over a vast number of thiol-containing proteins, collectively referred to as the redox-sensitive proteome. Although disruptions within this process, secondary to elevated peroxide exposure, have been linked to disease, the sources and mechanisms regulating increased peroxide burden remain poorly defined and as such are difficult to target using pharmacotherapy. Here we identify the pyruvate dehydrogenase complex (PDC) as a key source of H2O2 within skeletal muscle mitochondria under conditions of depressed glutathione redox buffering integrity. Treatment of permeabilized myofibers with varying concentrations of the glutathione-depleting agent 1-chloro-2,4-dinitrobenzene led to a dose-dependent increase in pyruvate-supported JH2O2 emission (the flux of H2O2 diffusing out of the mitochondrial matrix into the surrounding assay medium), with emission rates eventually rising to exceed those of all substrate combinations tested. This striking sensitivity to glutathione depletion was observed in permeabilized fibers prepared from multiple species and was specific to PDC. Physiological oxidation of the cellular glutathione pool after high-fat feeding in rodents was found to elevate PDC JH2O2 emission, as well as increasing the sensitivity of the complex to GSH depletion. These findings reveal PDC as a potential major site of H2O2 production that is extremely sensitive to mitochondrial glutathione redox status. </p>","PeriodicalId":505743,"journal":{"name":"Free radical biology & medicine","volume":" ","pages":"1201-1208"},"PeriodicalIF":7.4,"publicationDate":"2013-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.freeradbiomed.2013.09.008","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"31750646","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mechanism and biological relevance of blue-light (420-453 nm)-induced nonenzymatic nitric oxide generation from photolabile nitric oxide derivates in human skin in vitro and in vivo.","authors":"Christian Opländer,&nbsp;Annika Deck,&nbsp;Christine M Volkmar,&nbsp;Michael Kirsch,&nbsp;Jörg Liebmann,&nbsp;Matthias Born,&nbsp;Frank van Abeelen,&nbsp;Ernst E van Faassen,&nbsp;Klaus-Dietrich Kröncke,&nbsp;Joachim Windolf,&nbsp;Christoph V Suschek","doi":"10.1016/j.freeradbiomed.2013.09.022","DOIUrl":"https://doi.org/10.1016/j.freeradbiomed.2013.09.022","url":null,"abstract":"<p><p>Human skin contains photolabile nitric oxide (NO) derivates such as nitrite and S-nitrosothiols, which upon UVA radiation decompose under high-output NO formation and exert NO-specific biological responses such as increased local blood flow or reduced blood pressure. To avoid the injurious effects of UVA radiation, we here investigated the mechanism and biological relevance of blue-light (420-453 nm)-induced nonenzymatic NO generation from photolabile nitric oxide derivates in human skin in vitro and in vivo. As quantified by chemiluminescence detection (CLD), at physiological pH blue light at 420 or 453 nm induced a significant NO formation from S-nitrosoalbumin and also from aqueous nitrite solutions by a to-date not entirely identified Cu(1+)-dependent mechanism. As detected by electron paramagnetic resonance spectrometry in vitro with human skin specimens, blue light irradiation significantly increased the intradermal levels of free NO. As detected by CLD in vivo in healthy volunteers, irradiation of human skin with blue light induced a significant emanation of NO from the irradiated skin area as well as a significant translocation of NO from the skin surface into the underlying tissue. In parallel, blue light irradiation caused a rapid and significant rise in local cutaneous blood flow as detected noninvasively by using micro-light-guide spectrophotometry. Irradiation of human skin with moderate doses of blue light caused a significant increase in enzyme-independent cutaneous NO formation as well as NO-dependent local biological responses, i.e., increased blood flow. The effects were attributed to blue-light-induced release of NO from cutaneous photolabile NO derivates. Thus, in contrast to UVA, blue-light-induced NO generation might be therapeutically used in the treatment of systemic and local hemodynamic disorders that are based on impaired physiological NO production or bioavailability.</p>","PeriodicalId":505743,"journal":{"name":"Free radical biology & medicine","volume":" ","pages":"1363-1377"},"PeriodicalIF":7.4,"publicationDate":"2013-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.freeradbiomed.2013.09.022","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"31803903","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mild oxidative stress induces S-glutathionylation of STAT3 and enhances chemosensitivity of tumoural cells to chemotherapeutic drugs.","authors":"Elena Butturini,&nbsp;Alessandra Carcereri de Prati,&nbsp;Giulia Chiavegato,&nbsp;Antonella Rigo,&nbsp;Elisabetta Cavalieri,&nbsp;Elena Darra,&nbsp;Sofia Mariotto","doi":"10.1016/j.freeradbiomed.2013.09.015","DOIUrl":"https://doi.org/10.1016/j.freeradbiomed.2013.09.015","url":null,"abstract":"<p><p>STAT3 is a transcription factor constitutively activated in a variety of cancers that has a critical role in the inhibition of apoptosis and induction of chemoresistance. Inhibition of the STAT3 signaling pathway suppresses cell survival signals and leads to apoptosis in cancer cells, suggesting that direct inhibition of STAT3 function is a viable therapeutic approach. Herein, we identify the naturally occurring sesquiterpene lactone cynaropicrin as a potent inhibitor of both IL-6-inducible and constitutive STAT3 activation (IC50=12 μM). Cynaropicrin, which contains an α-β-unsaturated carbonyl moiety and acts as potent Michael reaction acceptor, induces a rapid drop in intracellular glutathione (GSH) concentration, thereby triggering S-glutathionylation of STAT3. Furthermore, glutathione ethylene ester, the cell permeable form of GSH, reverts the inhibitory action of cynaropicrin on STAT3 tyrosine phosphorylation. These findings suggest that this sesquiterpene lactone is able to induce redox-dependent post-translational modification of cysteine residues of STAT3 protein to regulate its function. STAT3 inhibition led to the suppression of two anti-apoptotic genes, Bcl-2 and survivin, in DU145 cells that constitutively express active STAT3. This event may be responsible for the decline in cell viability after cynaropicrin treatment. As revealed by PI/annexin-V staining, PARP cleavage, and DNA ladder formation, cynaropicrin cytotoxicity is mediated by apoptosis. Finally, cynaropicrin displayed a slight to strong synergism with two well-established chemotherapeutic drugs, cisplatin and docetaxel. Taken together our studies suggest that cynaropicrin suppresses the STAT3 pathway, leading to the down-regulation of STAT3-dependent gene expression and chemosensitization of tumour cells to chemotherapy.</p>","PeriodicalId":505743,"journal":{"name":"Free radical biology & medicine","volume":" ","pages":"1322-1330"},"PeriodicalIF":7.4,"publicationDate":"2013-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.freeradbiomed.2013.09.015","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"31782630","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Protein tyrosine phosphatase 1B inhibition ameliorates palmitate-induced mitochondrial dysfunction and apoptosis in skeletal muscle cells.","authors":"Gholamreza Taheripak,&nbsp;Salar Bakhtiyari,&nbsp;Masoumeh Rajabibazl,&nbsp;Parvin Pasalar,&nbsp;Reza Meshkani","doi":"10.1016/j.freeradbiomed.2013.09.019","DOIUrl":"https://doi.org/10.1016/j.freeradbiomed.2013.09.019","url":null,"abstract":"<p><p>Protein tyrosine phosphatase 1B (PTP1B) is a negative regulator of the insulin signaling pathway and is considered a promising therapeutic target in the treatment of diabetes. However, the role of PTP1B in palmitate-induced mitochondrial dysfunction and apoptosis in skeletal muscle cells has not been studied. Here we investigate the effects of PTP1B modulation on mitochondrial function and apoptosis and elucidate the underlying mechanisms in skeletal muscle cells. PTP1B inhibition significantly reduced palmitate-induced mitochondrial dysfunction and apoptosis in C2C12 cells, as these cells had increased expression levels of PGC-1α, Tfam, and NRF-1; enhanced ATP level and cellular viability; decreased TUNEL-positive cells; and decreased caspase-3 and -9 activity. Alternatively, overexpression of PTP1B resulted in mitochondrial dysfunction and apoptosis in these cells. PTP1B silencing improved mitochondrial dysfunction by an increase in the expression of SIRT1 and a reduction in the phosphorylation of p65 NF-κB. The protection from palmitate-induced apoptosis by PTP1B inhibition was also accompanied by a decrease in protein level of serine palmitoyl transferase, thus resulting in lower ceramide content in muscle cells. Exogenous addition of C2-ceramide to PTP1B-knockdown cells led to a reduced generation of reactive oxygen species (ROS), whereas PTP1B overexpression demonstrated an elevated ROS production in myotubes. In addition, PTP1B inhibition was accompanied by decreased JNK phosphorylation and increased insulin-stimulated Akt (Ser473) phosphorylation, whereas overexpression of PTP1B had the opposite effect. The overexpression of PTP1B also induced the nuclear localization of FOXO-1, but in contrast, suppression of PTP1B reduced palmitate-induced nuclear localization of FOXO-1. In summary, our results indicate that PTP1B modulation results in (1) alterations in mitochondrial function by changes in the activity of SIRT1/NF-κB/PGC-1α pathways and (2) changes in apoptosis that result from either a direct effect of PTP1B on the insulin signaling pathway or an indirect influence on ceramide content, ROS generation, JNK activation, and FOXO-1 nuclear translocation. </p>","PeriodicalId":505743,"journal":{"name":"Free radical biology & medicine","volume":" ","pages":"1435-1446"},"PeriodicalIF":7.4,"publicationDate":"2013-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.freeradbiomed.2013.09.019","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"31803534","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Peroxidase activity by MnSOD?","authors":"Stefan I Liochev,&nbsp;Irwin Fridovich","doi":"10.1016/j.freeradbiomed.2012.09.034","DOIUrl":"https://doi.org/10.1016/j.freeradbiomed.2012.09.034","url":null,"abstract":"","PeriodicalId":505743,"journal":{"name":"Free radical biology & medicine","volume":" ","pages":"1535"},"PeriodicalIF":7.4,"publicationDate":"2013-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.freeradbiomed.2012.09.034","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"30975723","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}