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ScienceDirect Publication: Free Radical Biology and Medicine
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  • Oxidative stress and mitochondrial dysfunction in parafacial respiratory group induced by maternal cigarette smoke exposure in rat offspring

    Publication date: December 2018

    Source: Free Radical Biology and Medicine, Volume 129

    Author(s): Fang Lei, Wen Wang, Yating Fu, Ji Wang, Yu Zheng

    Abstract

    Cigarette smoke (CS) exposure negatively affects neurodevelopment. We established a CS exposure rat model to determine how maternal CS exposure induces oxidative stress and mitochondrial dysfunction in parafacial respiratory group (pFRG) essential to central chemoreceptive regulation of normal breathing. Pregnant rats were exposed to CS during gestational days 1–20, and the offspring were studied on postnatal day 2. Our data showed that maternal CS exposure resulted in elevated accumulation of ROS, which left a footprint on DNA and lipid with increases in 8-hydroxy-2′-deoxyguanosine and malondialdehyde contents. Furthermore, maternal CS exposure induced decreases in manganese superoxide dismutase, catalase and glutathione reductase activities as well as reduction in glutathione content in pFRG in the offspring. Moreover, maternal exposure to CS led to mitochondrial ultrastructure changes, mitochondrial swelling, reduction in ATP generation, loss of mitochondrial membrane potential and increase in mitochondrial DNA copy number. These findings suggest that maternal exposure to CS alters normal development of pFRG that is critical for normal respiratory control.

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  • Quantitative assessment of cyanide in cystic fibrosis sputum and its oxidative catabolism by hypochlorous acid

    Publication date: December 2018

    Source: Free Radical Biology and Medicine, Volume 129

    Author(s): Jason P. Eiserich, Sean P. Ott, Tamara Kadir, Brian M. Morrissey, Keri A. Hayakawa, Michele A. La Merrill, Carroll E. Cross

    Abstract
    Rationale

    Cystic fibrosis (CF) patients are known to produce cyanide (CN-) although challenges exist in determinations of total levels, the precise bioactive levels, and specificity of its production by CF microflora, especially P. aeruginosa. Our objective was to measure total CN- levels in CF sputa by a simple and novel technique in P. aeruginosa positive and negative adult patients, to review respiratory tract (RT) mechanisms for the production and degradation of CN-, and to interrogate sputa for post-translational protein modification by CN- metabolites.

    Methods

    Sputa CN- concentrations were determined by using a commercially available CN- electrode, measuring levels before and after addition of cobinamide, a compound with extremely high affinity for CN-. Detection of protein carbamoylation was measured by Western blot.

    Measurements and main results

    The commercial CN- electrode was found to overestimate CN- levels in CF sputum in a highly variable manner; cobinamide addition rectified this analytical issue. Although P. aeruginosa positive patients tended to have higher total CN- values, no significant differences in CN- levels were found between positive and negative sputa. The inflammatory oxidant hypochlorous acid (HOCl) was shown to rapidly decompose CN-, forming cyanogen chloride (CNCl) and the carbamoylating species cyanate (NCO-). Carbamoylated proteins were found in CF sputa, analogous to reported findings in asthma.

    Conclusions

    Our studies indicate that CN- is a transient species in the inflamed CF airway due to multiple biosynthetic and metabolic processes. Stable metabolites of CN-, such as cyanate, or carbamoylated proteins, may be suitable biomarkers of overall CN- production in CF airways.

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  • ALK3 undergoes ligand-independent homodimerization and BMP-induced heterodimerization with ALK2

    Publication date: December 2018

    Source: Free Radical Biology and Medicine, Volume 129

    Author(s): Lisa Traeger, Inka Gallitz, Rohit Sekhri, Nicole Bäumer, Tanja Kuhlmann, Claudia Kemming, Michael Holtkamp, Jennifer-Christin Müller, Uwe Karst, Francois Canonne-Hergaux, Martina U. Muckenthaler, Donald B. Bloch, Andrea Olschewski, Thomas B. Bartnikas, Andrea U. Steinbicker

    Abstract

    The bone morphogenetic protein (BMP) type I receptors ALK2 and ALK3 are essential for expression of hepcidin, a key iron regulatory hormone. In mice, hepatocyte-specific Alk2 deficiency leads to moderate iron overload with periportal liver iron accumulation, while hepatocyte-specific Alk3 deficiency leads to severe iron overload with centrilobular liver iron accumulation and a more marked reduction of basal hepcidin levels. The objective of this study was to investigate whether the two receptors have additive roles in hepcidin regulation. Iron overload in mice with hepatocyte-specific Alk2 and Alk3 (Alk2/3) deficiency was characterized and compared to hepatocyte-specific Alk3 deficient mice. Co-immunoprecipitation studies were performed to detect the formation of ALK2 and ALK3 homodimer and heterodimer complexes in vitro in the presence and absence of ligands. The iron overload phenotype of hepatocyte-specific Alk2/3-deficient mice was more severe than that of hepatocyte-specific Alk3-deficient mice. In vitro co-immunoprecipitation studies in Huh7 cells showed that ALK3 can homodimerize in absence of BMP2 or BMP6. In contrast, ALK2 did not homodimerize in either the presence or absence of BMP ligands. However, ALK2 did form heterodimers with ALK3 in the presence of BMP2 or BMP6. ALK3-ALK3 and ALK2-ALK3 receptor complexes induced hepcidin expression in Huh7 cells. Our data indicate that: (I) ALK2 and ALK3 have additive functions in vivo, as Alk2/3 deficiency leads to a greater degree of iron overload than Alk3 deficiency; (II) ALK3, but not ALK2, undergoes ligand-independent homodimerization; (III) the formation of ALK2-ALK3 heterodimers is ligand-dependent and (IV) both receptor complexes functionally induce hepcidin expression in vitro.

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  • Cmk2 kinase is essential for survival in arsenite by modulating translation together with RACK1 orthologue Cpc2 in Schizosaccharomyces pombe

    Publication date: December 2018

    Source: Free Radical Biology and Medicine, Volume 129

    Author(s): Marta Sanchez-Marinas, David Gimenez-Zaragoza, Edgar Martin-Ramos, Julia Llanes, José Cansado, Maria Jesús Pujol, Oriol Bachs, Rosa Aligue

    Abstract

    Different studies have demonstrated multiple effects of arsenite on human physiology. However, there are many open questions concerning the mechanism of response to arsenite. Schizosaccharomyces pombe activates the Sty1 MAPK pathway as a common response to several stress conditions. The specificity of the response is due to the activation of different transcription factors and specific targets such the Cmk2 MAPKAP kinase. We have previously shown that Cmk2 is phosphorylated and activated by the MAPK Sty1 in response to oxidative stress. Here, we report that Cmk2 kinase is specifically necessary to overcome the stress caused by metalloid agents, in particular arsenite. Deletion of cmk2 increases the protein level of various components of the MAPK pathway. Moreover, Cmk2 negatively regulates translation through the Cpc2 kinase: the RACK1 orthologue in fission yeast. RACK1 is a receptor for activated C-kinase. Interestingly, RACK1 is a constituent of the eukaryotic ribosome specifically localized in the head region of the 40 S subunit. Cmk2 controls arsenite response through Cpc2 and it does so through Cpc2 ribosomal function, as observed in genetic analysis using a Cpc2 mutant unable to bind to ribosome. These findings suggest a role for Cmk2 in regulating translation and facilitating adaptation to arsenite stress in the ribosome.

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  • A novel S-nitrosocaptopril monohydrate for pulmonary arterial hypertension: H2O and –SNO intermolecular stabilization chemistry

    Publication date: December 2018

    Source: Free Radical Biology and Medicine, Volume 129

    Author(s): Yuyang Zhou, Min Lin, Jie Wang, Fan Chen, Feiyang Li, Wenge Chen, Longyu Han, Chiahung Wang, Jianming Chen, Jing-Wei Shao, Lee Jia

    Abstract

    S-nitrosocaptopril (CapNO) possesses dual capacities of both Captopril and an NO donor with enhanced efficacy and reduced side effects. CapNO crystals are difficult to make due to its unstable S-NO bond. Here, we report a novel stable S-nitrosocaptopril monohydrate (CapNO·H2O) that is stabilized by intermolecular five-membered structure, where one H of H2O forms a hydrogen bond with O- of the stable resonance zwitterion Cap–S+=N–O-, and the O in H2O forms the dipole-dipole interaction with S+ through two unpaired electrons. With the chelation and common ion effect, we synthesized and characterized CapNO·H2O that is stable at 4 °C for 180 days and thereafter without significant degradation. Compared to Captopril, CapNO showed direct vasorelaxation and beneficial effect on PAH rats, and could be self-assembled in rat stomach when Captopril and NaNO2 were given separately. This novel CapNO·H2O with low entropy paves an avenue for its clinical trials and commercialization.

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  • Lack of superoxide dismutase in a rad51 mutant exacerbates genomic instability and oxidative stress-mediated cytotoxicity in Saccharomyces cerevisiae

    Publication date: December 2018

    Source: Free Radical Biology and Medicine, Volume 129

    Author(s): Ji Eun Choi, Seo-Hee Heo, Myung Ju Kim, Woo-Hyun Chung

    Abstract

    A genetic analysis of synthetic lethal interactions in yeast revealed that the mutation of SOD1, encoding an antioxidant enzyme that scavenges superoxide anion radical, impaired the growth of a set of mutants defective in homologous recombination (HR) pathway. Hence, SOD1 inhibition has been proposed as a promising approach for the selective killing of HR-deficient cancer cells. However, we show that the deletion of RAD51 and SOD1 is not synthetic lethal but displays considerably slow growth and synergistic sensitivity to both reactive oxygen species (ROS)- and DNA double-strand break (DSB)-generating drugs in the budding yeast Saccharomyces cerevisiae. The function of Sod1 in regard to Rad51 is dependent on Ccs1, a copper chaperone for Sod1. Sod1 deficiency aggravates genomic instability in conjunction with the absence of Rad51 by inducing DSBs and an elevated mutation frequency. Inversely, lack of Rad51 causes a Sod1 deficiency-derived increase of intracellular ROS levels. Taken together, our results indicate that there is a significant and specific crosstalk between two major cellular damage response pathways, ROS signaling and DSB repair, for cell survival.

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  • An intronic single nucleotide polymorphism in the MUTYH gene is associated with increased risk for HCV-induced hepatocellular carcinoma

    Publication date: December 2018

    Source: Free Radical Biology and Medicine, Volume 129

    Author(s): Akira Sakurada, Koji Miyanishi, Shingo Tanaka, Masanori Sato, Hiroki Sakamoto, Yutaka Kawano, Kohichi Takada, Yusaku Nakabeppu, Masayoshi Kobune, Junji Kato

    Abstract
    Background & aims

    The role of base excision repair genes in human hepatocarcinogenesis has not yet been explored. Here, we investigated relationships between variants of these genes and the risk of developing hepatocellular carcinoma (HCC).

    Methods

    Nineteen tagging SNPs in base excision repair genes (including MUTYH, OGG1 and MTH1) were genotyped using iPLEX assays; one significant SNP was found and confirmed in Japanese patients with chronic hepatitis C (CHC) (n = 38 HCC and 55 controls). The effects of modifying the intronic variants were determined by luciferase assays. MUTYH-null mice were used to examine the involvement of oxidative stress and DNA repair enzymes in hepatocarcinogenesis.

    Results

    Significant associations were found for a single intron SNP (rs3219487) in the MUTYH gene. The risk of developing HCC in patients with A/A or G/A genotypes was higher than in those with the G/G genotype (OR = 9.27, 95% CI = 2.39 −32.1, P = 0.0005). MUTYH mRNA levels in both peripheral mononuclear cells were significantly lower in G/A or A/A genotyped subjects (P = 0.0157 and 0.0108, respectively). We found that −2000 in the MUTYH promoter region is involved in enhanced expression of MUTYH by insertion of a major allele sequence of rs3219487. Liver tumors were observed in MUTYH-null mice after 12 months´ high iron diet, but no tumors developed when dietary anti-oxidant (N-Acetyl-L-cysteine) was also provided.

    Conclusions

    CHC patients with the rs3219487 adenine allele had a significantly increased risk of developing HCC. MUTYH-null mice with iron-associated oxidative stress were susceptible to development of liver tumors unless prevented by dietary anti-oxidants.

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  • Axin-2 knockdown promote mitochondrial biogenesis and dopaminergic neurogenesis by regulating Wnt/β-catenin signaling in rat model of Parkinson's disease

    Publication date: December 2018

    Source: Free Radical Biology and Medicine, Volume 129

    Author(s): Sonu Singh, Akanksha Mishra, Soni Jignesh Mohanbhai, Virendra Tiwari, Rajnish Kumar Chaturvedi, Sukant Khurana, Shubha Shukla

    Abstract

    Wnts and the components of Wnt/β-catenin signaling are widely expressed in midbrain and required to control the fate specification of dopaminergic (DAergic) neurons, a neuronal population that specifically degenerate in Parkinson's disease (PD). Accumulating evidence suggest that mitochondrial dysfunction plays a key role in pathogenesis of PD. Axin-2, a negative regulator of Wnt/β-catenin signaling affects mitochondrial biogenesis and death/birth of new DAergic neurons is not fully explored. We investigated the functional role of Axin-2/Wnt/β-catenin signaling in mitochondrial biogenesis and DAergic neurogenesis in 6-hydroxydopamine (6-OHDA) induced rat model of PD-like phenotypes. We demonstrate that single unilateral injection of 6-OHDA into the medial forebrain bundle (MFB) potentially dysregulates Wnt/β-catenin signaling in substantia nigra pars compacta (SNpc). We used shRNA lentiviruses to genetically knockdown Axin-2 to up-regulate Wnt/β-catenin signaling in SNpc in parkinsonian rats. Genetic knockdown of Axin-2 up-regulates Wnt/β-catenin signaling by destabilizing the β-catenin degradation complex in SNpc in parkinsonian rats. Axin-2 shRNA mediated activation of Wnt/β-catenin signaling improved behavioural functions and protected the nigral DAergic neurons by increasing mitochondrial functionality in parkinsonian rats. Axin-2 shRNA treatment reduced apoptotic signaling, autophagy and ROS generation and improved mitochondrial membrane potential which promotes mitochondrial biogenesis in SNpc in parkinsonian rats. Interestingly, Axin-2 shRNA-mediated up-regulation of Wnt/β-catenin signaling enhanced net DAergic neurogenesis by regulating proneural genes (Nurr-1, Pitx-3, Ngn-2, and NeuroD1) and mitochondrial biogenesis in SNpc in parkinsonian rats. Therefore, our data suggest that pharmacological/genetic manipulation of Wnt signaling that enhances the endogenous regenerative capacity of DAergic neurons may have implication for regenerative approaches in PD.

    Graphical abstract

    A proposed schematic representation of the means by which Promote Mitochondrial Biogenesis and Dopaminergic Neurogenesis by regulating Wnt/β-catenin Signaling in Rat Model of Parkinson's Disease.

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  • AMPK/PGC1α activation by melatonin attenuates acute doxorubicin cardiotoxicity via alleviating mitochondrial oxidative damage and apoptosis

    Publication date: December 2018

    Source: Free Radical Biology and Medicine, Volume 129

    Author(s): Dong Liu, Zhiqiang Ma, Shouyin Di, Yang Yang, Jingang Yang, Liqun Xu, Russel J. Reiter, Shubin Qiao, Jiansong Yuan

    Abstract

    Doxorubicin (DOX) is a highly effective anticancer anthracycline drug, but its side effects at the level of the heart has limited its widespread clinical application. Melatonin is a documented potent antioxidant, nontoxic and cardioprotective agent, and it is involved in maintaining mitochondrial homeostasis and function. The present study established acute DOX-induced cardiotoxicity models in both H9c2 cells incubated with 1 μM DOX and C57BL/6 mice treated with DOX (20 mg/kg cumulative dose). Melatonin markedly alleviated the DOX-induced acute cardiac dysfunction and myocardial injury. Both in vivo and in vitro studies verified that melatonin inhibited DOX-induced mitochondrial dysfunction and morphological disorders, apoptosis, and oxidative stress via the activation of AMPK and upregulation of PGC1α with its downstream signaling (NRF1, TFAM and UCP2). These effects were reversed by the use of AMPK siRNA or PGC1α siRNA in H9c2 cells, and were also negated by the cotreatment with AMPK inhibitor Compound C in vivo. Moreover, PGC1α knockdown was without effect on the AMPK phosphorylation induced by melatonin in the DOX treated H9c2 cells. Therefore, AMPK/PGC1α pathway activation may represent a new mechanism for melatonin exerted protection against acute DOX cardiotoxicity through preservation of mitochondrial homeostasis and alleviation of oxidative stress and apoptosis.

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  • MnSOD mediates shear stress-promoted tumor cell migration and adhesion

    Publication date: December 2018

    Source: Free Radical Biology and Medicine, Volume 129

    Author(s): Shijun Ma, Afu Fu, Sierin Lim, Geraldine Giap Ying Chiew, Kathy Qian Luo

    Abstract

    Circulation of cancer cells in the bloodstream is a vital step for distant metastasis, during which cancer cells are exposed to hemodynamic shear stress (SS). The actions of SS on tumor cells are complicated and not fully understood. We previously reported that fluidic SS was able to promote migration of breast cancer cells by elevating the cellular ROS level. In this study, we further investigated the mechanisms regulating SS-promoted cell migration and identified the role of MnSOD in the related pathway. We found that SS could enhance tumor cell adhesion to extracellular matrix and endothelial monolayer, and MnSOD also regulated this process. Briefly, SS stimulates the generation of mitochondrial superoxide in tumor cells. MnSOD then converts superoxide into hydrogen peroxide, which activates ERK1/2 to promote tumor cell migration and activates FAK to promote tumor cell adhesion. Combining our previous and present studies, we present experimental evidence on the pro-metastatic effects of hemodynamic SS and reveal the underlying mechanism. Our findings provide new insights into the nature of cancer metastasis and the understanding of tumor cell responses to external stresses and have valuable implications for cancer therapy development.

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