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Free Radical Biology and Medicine (FRBM)

Reduced lifespan of mice lacking catalase correlates with altered lipid metabolism without oxidative damage or premature aging

Publication date: 1 May 2019 Source: Free Radical Biology and Medicine, Volume 135 Author(s): José Raúl Pérez-Estrada, David Hernández-García, Francisco Leyva-Castro, Javier Ramos-León, Osiris Cuevas-Benítez, Mauricio Díaz-Muñoz, Susana Castro-Obregón, Ramiro Ramírez-Solís, Celina García, Luis Covarrubias AbstractThe relationship between the mechanisms that underlie longevity and aging and the metabolic alterations due to feeding conditions has not been completely defined. In the present work, through the deletion of the gene encoding catalase, hydrogen peroxide (H2O2) was uncovered as a relevant regulator of longevity and of liver metabolism. Mice lacking catalase (Cat−/−) fed ad libitum with a regular diet showed a shorter lifespan than wild type mice, which correlated with reduced body weight, blood glucose levels and liver fat accumulation, but not with increased oxidative damage or consistent premature aging. High fat diet (HFD) and fasting increased oxidative damage in the liver of wild type animals but, unexpectedly, this was not the case for that of Cat−/− mice. Interestingly, although HFD feeding similarly increased the body weight of Cat−/− and wild-type mice, hyperglycemia and liver steatosis did not develop in the former. Fat accumulation due to fasting, on the other hand, was diminished in mice lacking catalase, which correlated with increased risk of death and low ketone body blood levels. Alteration in expression of some metabolic genes in livers of catalase deficient mice was consistent with reduced lipogenesis. Specifically, Pparγ2 expression up-regulation in response to a HFD and down-regulation upon fasting was lower and higher, respectively, in livers of Cat−/− than of wild type mice, and a marked decay was observed during Cat−/− mice aging. We propose that catalase regulates lipid metabolism in the liver by an evolutionary conserved mechanism that is determinant of lifespan without affecting general oxidative damage. Graphical abstract

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Differential induction of nuclear factor-like 2 signature genes with toll-like receptor stimulation

Publication date: 1 May 2019 Source: Free Radical Biology and Medicine, Volume 135 Author(s): Sonia Ingram, Manuela Mengozzi, Sandra Sacre, Lisa Mullen, Pietro Ghezzi AbstractInflammation is associated with production of reactive oxygen species (ROS) and results in the induction of thioredoxin (TXN) and peroxiredoxins (PRDXs) and activation of nuclear factor-like 2 (Nrf2). In this study we have used the mouse RAW 264.7 macrophage and the human THP-1 monocyte cell line to investigate the pattern of expression of three Nrf2 target genes, PRDX1, TXN reductase (TXNRD1) and heme oxygenase (HMOX1), by activation of different Toll-like receptors (TLRs). We found that, while the TLR4 agonist lipopolysaccharide (LPS) induces all three genes, the pattern of induction with agonists for TLR1/2, TLR3, TLR2/6 and TLR7/8 differs depending on the gene and the cell line. In all cases, the extent of induction was HMOX1>TXNRD1>PRDX1. Since LPS was a good inducer of all genes in both cell lines, we studied the mechanisms mediating LPS induction of the three genes using mouse RAW 264.7 cells. To assess the role of ROS we used the antioxidant N-acetylcysteine (NAC). Only LPS induction of HMOX1 was inhibited by NAC while that of TXNRD1 and PRDX1 was unaffected. These three genes were also induced by phorbol myristate acetate (PMA), a ROS-inducer acting by activation of protein kinase C (PKC). The protein kinase inhibitor staurosporine inhibited the induction of all three genes by PMA but only that of HMOX1 by LPS. This indicates that activation of these genes by inflammatory agents is regulated by different mechanisms involving either ROS or protein kinases, or both. Graphical abstract

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Traffic-related particulate matter exposure induces nephrotoxicity in vitro and in vivo

Publication date: 1 May 2019 Source: Free Radical Biology and Medicine, Volume 135 Author(s): Yung-Ho Hsu, Hsiao-Chi Chuang, Yu-Hsuan Lee, Yuh-Feng Lin, Yi-Jie Chen, Ta-Chih Hsiao, Mei-Yi Wu, Hui-Wen Chiu AbstractTraffic emission is responsible for most small-sized particulate matter (PM) air pollution in urban areas. Several recent studies have indicated that traffic-related PM may aggravate kidney disease. Furthermore, exposure to particulate air pollution may be related to the risk of chronic kidney disease (CKD). However, the underlying molecular mechanisms have not been adequately addressed. In the present study, we studied the mechanisms of renal damage that might be associated with exposure to PM. In a real world of whole-body exposure to traffic-related PM model for 3–6 months, PM in urban ambient air can affect kidney function and induce autophagy, endoplasmic reticulum (ER) stress and apoptosis in kidney tissues. Exposure to traffic-related diesel particulate matter (DPM) led to a reduction in cell viability in human kidney tubular epithelial cells HK-2. DPM increased mitochondrial reactive oxygen species (ROS) and decreased the mitochondrial membrane potential. Furthermore, DPM induced ER stress and activated the unfolded protein response (UPR) pathway. Eventually, DPM exposure induced caspase pathways and triggered apoptosis. In addition, DPM induced autophagy through the inhibition of the Akt/mTOR pathway. Autophagy inhibition resulted in significantly increased cytotoxicity and apoptosis. These findings suggest that air pollution in urban areas may cause nephrotoxicity and autophagy as a protective role in PM-induced cytotoxicity. Graphical abstract

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Peroxiredoxin expression and redox status in neutrophils and HL-60 cells

Publication date: 1 May 2019 Source: Free Radical Biology and Medicine, Volume 135 Author(s): Luiz F. de Souza, Andree G. Pearson, Paul E. Pace, Alcir L. Dafre, Mark B. Hampton, Flávia C. Meotti, Christine C. Winterbourn AbstractPeroxiredoxins (Prxs) are thiol peroxidases with a key role in antioxidant defense and redox signaling. They could be important in neutrophils for handling the large amount of oxidants that these cells produce. We investigated the redox state of Prx1 and Prx2 in HL-60 promyelocytic cells differentiated to neutrophil-like cells (dHL-60) and in human neutrophils. HL-60 cell differentiation with dimethyl sulfoxide caused a large decrease in expression of both Prxs, and all-trans retinoic acid also decreased Prx1 expression. Prx1 was mostly reduced in dHL-60 cells. NADPH oxidase activation by phorbol myristate acetate (PMA) or ingestion of Staphylococcus aureus induced rapid oxidation to disulfide-linked dimers, and eventually hyperoxidation. The NADPH oxidase inhibitor, diphenyleneiodonium, prevented Prx1 dimerization in stimulated dHL-60 cells, and decreased the extent of oxidation under resting conditions. In contrast, Prx1 and Prx2 were present in neutrophils from human blood as disulfides, and PMA or S. aureus caused no further oxidation. They remained oxidized on incubation with diphenyleneiodonium in media. Although this suggests that Prx redox cycling could be deficient in neutrophils, thioredoxin expression and thioredoxin reductase activity were similar in neutrophils and dHL-60 cells. Additionally, neutrophil thioredoxin was initially reduced and underwent oxidation after PMA activation. Thus, although the Prxs respond to oxidant generation in dHL-60 cells, in neutrophils they appear “locked” as disulfides. On this basis we propose that neutrophil Prxs are inefficient antioxidants and contribute little to peroxide removal during the oxidative burst, and speculate that they might be involved in other cell processes. Graphical abstract

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Promotion of HeLa cells apoptosis by cynaropicrin involving inhibition of thioredoxin reductase and induction of oxidative stress

Publication date: 1 May 2019 Source: Free Radical Biology and Medicine, Volume 135 Author(s): Tianyu Liu, Junmin Zhang, Xiao Han, Jianqiang Xu, Yueting Wu, Jianguo Fang AbstractCancer is considered as one of the highly mortal diseases globally. This is largely due to the lack of efficacious medicines for tumors, and thus development of potent anticancer agents is urgently needed. The thioredoxin (Trx) system is crucial to the survival ability of cells and its expression is up-regulated in many human tumors. Recently, increasing evidence has been established that mammalian thioredoxin reductase (TrxR), a selenocysteine-containing protein and the core component of the thioredoxin system, is a promising therapeutic target. The sesquiterpene lactone compound cynaropicrin (CYN), a major component of Cynara scolymus L., has shown multiple pharmacological functions, especially the anticancer effect, in many experimental models. Most of these functions are concomitant with the production of reactive oxygen species (ROS). Nevertheless, the target of this promising natural anticancer product in redox control has rarely been explored. In this study, we showed that CYN induces apoptosis of Hela cells. Mechanistic studies demonstrated that CYN impinges on the thioredoxin system via inhibition of TrxR, which leads to Trx oxidation and ROS accumulation in HeLa cells. Particularly, the cytotoxicity of CYN is enhanced through the genetic knockdown of TrxR, supporting the pharmacological effect of CYN is relevant to its inhibition of TrxR. Together, our studies reveal an unprecedented mechanism accounting for the anticancer effect of CYN and identify a promising therapeutic agent worthy of further development for cancer therapy. Graphical abstract

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Redox Biology

2-O-β-d-glucopyranosyl-l-ascorbic acid, a novel vitamin C derivative from Lycium barbarum, prevents oxidative stress

Publication date: June 2019 Source: Redox Biology, Volume 24 Author(s): Shen-Fei Wang, Xin Liu, Mo-Yu Ding, Shuangcheng Ma, Jing Zhao, Ying Wang, Shaoping Li AbstractReducing agents are crucial for the management of maladaptive inflammation-induced macrophage death and hematopoietic toxicity of chemotherapy. 2-O-β-d-glucopyranosyl-l-ascorbic acid (AA-2βG), a unique AA (or vitamin C) derivative identified in Lycium barbarum, exhibited enhanced free radical scavenging activity compared with AA and its synthetic derivative AA-2αG. AA-2βG protected hydrogen peroxide-induced cell death in murine macrophage RAW264.7 cells. Treatment with AA-2βG eliminated oxidative stress and the ratio of cellular glutathione to glutathione disulfide more effectively than AA and AA-2αG. AA-2βG also significantly reduced the fluorescent intensity of DCFH-DA triggered by chemotherapeutic agent camptotehcin-11 but not fluorouracil. AA, AA-2αG, and AA-2βG significantly decreased Keap-1expression, and increased the expression levels of nuclear factor E2-related factor 2 (Nrf2) and heme oxygenase-1. All compounds triggered the nuclear translocation of Nrf2, while the ability of AA-2βG to enhance the Nrf2-DNA binding affinity was approximately two fold as those of AA and AA-2αG. Sodium ascorbate cotransporters (SVCT) inhibitors, sulfinpyrazone, phloretin, and 3-O-methyglucose, potently abrogated the free radical scavenging activities of AA, AA-2αG, and AA-2βG. The cellular uptake efficacy of AA-2αG and AA-2βG was less than 10% of AA, while the inhibition of SVCT with sulfinpyrazone considerably diminished the uptake efficacy of these compounds. AA-2αG and AA-2βG are more stable in the Fenton reagents than AA. In summary, AA-2βG from L. barbarum with excellent free radical scavenging activity is a promising natural AA derivative for further pharmacological evaluation.

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Interactions between plasma copper concentrations and SOD1 gene polymorphism for impaired glucose regulation and type 2 diabetes

Publication date: June 2019 Source: Redox Biology, Volume 24 Author(s): Jiawei Yin, Xiaoqian Wang, Shuzhen Li, Yalun Zhu, Sijing Chen, Peiyun Li, Cheng Luo, Yue Huang, Xiaoqin Li, Xueting Hu, Wei Yang, Wei Bao, Zhilei Shan, Liegang Liu AbstractAimsTo examine the associations of plasma copper concentrations and superoxide dismutase 1 (SOD1) polymorphisms as well as their gene-environment interaction with newly diagnosed impaired glucose regulation (IGR) and type 2 diabetes (T2D). MethodsWe performed a large case-control study in 2520 Chinese Han subjects: 1004 newly diagnosed T2D patients, 512 newly diagnosed IGR patients and 1004 individuals with normal glucose tolerance. ResultsAfter multivariable adjustment, the ORs (95% CIs) of T2D across tertiles of plasma copper were 1.00 (reference), 1.85 (95% CI: 1.39, 2.45), and 4.21 (95% CI: 3.20, 5.55) (P-trend < 0.001). Each SD increment of ln-transformed plasma copper was associated with 104% higher odds (OR 2.04, 95%CI 1.82–2.28) increment in ORs of T2D. Meanwhile, compared with the GG genotype of rs2070424, the OR of T2D associated with AG and AA genotypes were 1.44 (95% CI 1.15–1.81) and 1.74 (95% CI 1.33–2.28), respectively. In addition, the positive association between plasma copper and T2D was modified by rs2070424 genotypes. The adjusted ORs and 95% CIs of T2D per SD increment of ln-transformed plasma copper were 2.40 (1.93–2.99), 1.85 (1.59–2.16) and 1.76 (1.44–2.15) in rs2070424 GG, AG and GG carriers respectively (P for interaction < 0.05). Similar interactions were also found for IGR and IGR&T2D. When the joint effects were examined, individuals with rs2070424 AA genotype and the highest tertile of plasma copper concentration had a much higher risk of IGR&T2D (OR 5.34, 95% CI 3.48–8.21) than those with rs2070424 GG genotype and the lowest tertile of plasma copper concentrations. ConclusionsPlasma copper concentrations are positively and significantly associated with IGR as well as T2D, and these associations may be modified by SOD1 polymorphism. Fur

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c-Myc activation promotes cofilin-mediated F-actin cytoskeleton remodeling and telomere homeostasis as a response to oxidant-based DNA damage in medulloblastoma cells

Publication date: June 2019 Source: Redox Biology, Volume 24 Author(s): Anna Lewinska, Jolanta Klukowska-Rötzler, Anna Deregowska, Jagoda Adamczyk-Grochala, Maciej Wnuk AbstractMedulloblastoma (MB) is a common and highly aggressive pediatric brain tumor of a heterogeneous nature. According to transcriptome-based profiling, four molecular subgroups of MB have been revealed, namely WNT, SHH, Group 3 and Group 4. High MYC mRNA expression and MYC gene amplification in MB have been considered as indicators of poor prognosis. However, the role of c-Myc in MB biology is still not well established. In the present study, the effects of c-Myc activation in UW228-MycER MB cell line were investigated using 4-hydroxytamoxifen (4-OHT) induction system. Upon 4-OHT stimulation, an increase in metabolic activity, large-cell/anaplastic (LC/A) phenotype and oxidative stress-mediated DNA damage were observed. However, 53BP1 foci were not implicated in DNA damage response. Instead, cofilin nuclear translocation, changes in F-actin cytoskeleton and the levels of cytoskeletal proteins were shown. Moreover, the telomere length was found to be unaffected that may be associated with the upregulation of TRF proteins. Transcription of nascent RNA (synthesis of new rRNA) and the expression of RNA polymerase I-specific transcription initiation factor RRN3/TIF-IA were also elevated. Moreover, increased levels of DNMT2, a modulator of stress responses, were observed. A small fraction of cells responded differently as oncogene-induced senescence was also noticed. We postulate that c-Myc-mediated modulation of genetic stability of MB cells may trigger cellular heterogeneity and affect adaptive responses to changing environment.

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Nitric oxide-donor/PARP-inhibitor combination: A new approach for sensitization to ionizing radiation

Publication date: June 2019 Source: Redox Biology, Volume 24 Author(s): Aaron Wilson, Vijay Menon, Zubair Khan, Asim Alam, Larisa Litovchick, Vasily Yakovlev AbstractRecently, clinical development of PARP inhibitors (PARPi) expanded from using them as a single agent to combining them with DNA-damaging therapy to derive additional therapeutic benefit from stimulated DNA damage. Furthermore, inhibiting PARP in cancers with BRCA1/2 mutations has been shown to be an effective synthetic lethality approach either as a single agent or in combination with the different DNA damaging agents: chemotherapy or ionizing radiation (IR). However, inherited BRCA1/2 mutations account only for 5–10% of breast cancers, 10–15% of ovarian cancers, and lesser for the other cancers. Hence, for most of the cancer patients with BRCA1/2-proficient tumors, sensitization to DNA-damaging agents with PARPi is significantly less effective. We recently demonstrated that moderate, non-toxic concentrations of NO-donors inhibited BRCA1 expression, with subsequent inhibition of error-free HRR and increase of error-prone non-homologous end joining (NHEJ). We also demonstrated that the effect of NO-dependent block of BRCA1 expression can only be achieved in the presence of oxidative stress, a condition that characterizes the tumor microenvironment and is also a potential effect of IR. Hence, NO-donors in combination with PARPi, with effects limited by tumor microenvironment and irradiated area, suggest a precise tumor-targeted approach for radio-sensitization of BRCA1/2-proficient tumors. The combination with NO-donors allows PARPi to be successfully applied to a wider variety of tumors. The present work demonstrates a new drug combination (NO-donors and PARP-inhibitors) which demonstrated a high potency in sensitization of wide variety of tumors to ionizing radiation treatment. Graphical abstract

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The vitamin E derivative garcinoic acid from Garcinia kola nut seeds attenuates the inflammatory response

Publication date: June 2019 Source: Redox Biology, Volume 24 Author(s): Maria Wallert, Julia Bauer, Stefan Kluge, Lisa Schmölz, Yung-Chih Chen, Melanie Ziegler, Amy K. Searle, Alexander Maxones, Martin Schubert, Maria Thürmer, Helmut Pein, Andreas Koeberle, Oliver Werz, Marc Birringer, Karlheinz Peter, Stefan Lorkowski AbstractThe plant Garcinia kola is used in African ethno-medicine to treat various oxidation- and inflammation-related diseases but its bioactive compounds are not well characterized. Garcinoic acid (GA) is one of the few phytochemicals that have been isolated from Garcinia kola. We investigated the anti-inflammatory potential of the methanol extract of Garcinia kola seeds (NE) and purified GA, as a major phytochemical in these seeds, in lipopolysaccharide (LPS)-activated mouse RAW264.7 macrophages and its anti-atherosclerotic potential in high fat diet fed ApoE−/− mice. This study outlines an optimized procedure for the extraction and purification of GA from Garcinia kola seeds with an increased yield and a purity of >99%. We found that LPS-induced upregulation of iNos and Cox2 expression, and the formation of the respective signaling molecules nitric oxide and prostanoids, were significantly diminished by both the NE and GA. In addition, GA treatment in mice decreased intra-plaque inflammation by attenuating nitrotyrosinylation. Further, modulation of lymphocyte sub-populations in blood and spleen have been detected, showing immune regulative properties of GA. Our study provides molecular insights into the anti-inflammatory activities of Garcinia kola and reveals GA as promising natural lead for the development of multi-target drugs to treat inflammation-driven diseases. Graphical abstract

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