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oxidative stress


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  • Chronic oxidative stress causes amplification and overexpression of ptprz1 protein tyrosine phosphatase to activate beta-catenin pathway. 18055543

    Ferric nitrilotriacetate induces oxidative renal tubular damage via Fenton-reaction, which subsequently leads to renal cell carcinoma (RCC) in rodents. Here, we used gene expression microarray and array-based comparative genomic hybridization analyses to find target oncogenes in this model. At the common chromosomal region of amplification (4q22) in rat RCCs, we found ptprz1, a tyrosine phosphatase (also known as protein tyrosine phosphatase zeta or receptor tyrosine phosphatase beta) highly expressed in the RCCs. Analyses revealed genomic amplification up to eightfold. Despite scarcity in the control kidney, the amounts of PTPRZ1 were increased in the kidney after 3 weeks of oxidative stress, and mRNA levels were increased 16 approximately 552-fold in the RCCs. Network analysis of the expression revealed the involvement of the beta-catenin pathway in the RCCs. In the RCCs, dephosphorylated beta-catenin was translocated to nuclei, resulting in the expression of its target genes cyclin D1, c-myc, c-jun, fra-1, and CD44. Furthermore, knockdown of ptprz1 with small interfering RNA (siRNA), in FRCC-001 and FRCC-562 cell lines established from the induced RCCs, decreased the amounts of nuclear beta-catenin and suppressed cellular proliferation concomitant with a decrease in the expression of target genes. These results demonstrate that chronic oxidative stress can induce genomic amplification of ptprz1, activating beta-catenin pathways without the involvement of Wnt signaling for carcinogenesis. Thus, iron-mediated persistent oxidative stress confers an environment for gene amplification.
    Dokumententyp:
    Referenz
    Produkbestellnummer:
    06-427
    Produktbezeichnung:
    Anti-Phosphotyrosine Antibody

  • Role of oxidative stress in the increased activation of signal transducers and activators of transcription-3 in the fatty livers of obese Zucker rats. 15349118

    BACKGROUND: Fatty livers have chronic oxidative stress, which could activate several transcription factors. We hypothesized that fatty livers of obese rats have increased activation of signal transducers and activators of transcription-1 and transcription-3 (Stat-1 and Stat-3) and that tocopherol treatment will decrease Stat activation. METHODS: Obese (Ob) and lean (Ln) Zucker rats with or without tocopherol treatment were used. Western blots of liver nuclear and cytoplasmic extracts to assess phosphorylated and total Stat-3 and tyrosine kinases Jak-2 and Tyk-2, immunohistochemistry to assess distribution of phosphoStat-3, and gel shift assays to assess Stat and nuclear factor kappa B binding were performed. Interleukin-6 serum levels and hepatic transcripts were determined by immunoassay and reverse polymerase chain reaction with Southern blotting, respectively. RESULTS: Livers of Ob animals had increased nuclear phosphoStat-3, decreased cytoplasmic Stat-3, and increased Stat-3 binding. Serum interleukin-6 was not measurable in either Ob or Ln animals and hepatic transcript levels were not significantly different. Tocopherol administration decreased nuclear phosphoStat-3, increased cytoplasmic Stat-3, and decreased Stat-3 binding activity. CONCLUSIONS: Chronic oxidative stress in fatty livers is associated with increased Stat-3 activation and decreased cytosolic Stat-3. Tocopherol treatment decreases Stat-3 activation and increases cytosolic Stat-3. Tocopherol-induced changes in Stat-3 may play a role in its beneficial effects in hepatic ischemia in fatty livers.
    Dokumententyp:
    Referenz
    Produkbestellnummer:
    06-255
    Produktbezeichnung:
    Anti-JAK2 Antibody

  • Local oxidative stress expansion through endothelial cells--a key role for gap junction intercellular communication. 22911831

    Major circulation pathologies are initiated by oxidative insult expansion from a few injured endothelial cells to distal sites; this possibly involves mechanisms that are important to understanding circulation physiology and designing therapeutic management of myocardial pathologies. We tested the hypothesis that a localized oxidative insult of endothelial cells (ECs) propagates through gap junction inter-cellular communication (GJIC).Cultures comprising the bEnd.3 cell line, that have been established and recognized as suitable for examining communication among ECs, were used to study the propagation of a localized oxidative insult to remote cells. Spatially confined near infrared illumination of parental or genetically modified bEnd.3 cultures, pretreated with the photosensitizer WST11, generated O(2)•(-) and •OH radicals in the illuminated cells. Time-lapse fluorescence microscopy, utilizing various markers, and other methods, were used to monitor the response of non-illuminated bystander and remote cells. Functional GJIC among ECs was shown to be mandatory for oxidative insult propagation, comprising de-novo generation of reactive oxygen and nitrogen species (ROS and RNS, respectively), activation and nuclear translocation of c-Jun N-terminal kinase, followed by massive apoptosis in all bystander cells adjacent to the primarily injured ECs. The oxidative insult propagated through GJIC for many hours, over hundreds of microns from the primary photogeneration site. This wave is shown to be limited by intracellular ROS scavenging, chemical GJIC inhibition or genetic manipulation of connexin 43 (a key component of GJIC).Localized oxidative insults propagate through GJIC between ECs, while stimulating de-novo generation of ROS and RNS in bystander cells, thereby driving the insult's expansion.
    Dokumententyp:
    Referenz
    Produkbestellnummer:
    05-233
    Produktbezeichnung:
    Anti-Nitrotyrosine Antibody, clone 1A6

  • Reduction of oxidative stress, amyloid deposition, and memory deficit by manganese superoxide dismutase overexpression in a transgenic mouse model of Alzheimer's disease. 19346295

    In Alzheimer's disease (AD), oxidative stress is present early and contributes to disease pathogenesis. We previously reported that in Tg19959 transgenic AD mice, partial deficiency of the mitochondrial antioxidant enzyme manganese superoxide dismutase (MnSOD) exacerbated amyloid pathology. We therefore asked whether MnSOD overexpression would prove beneficial against AD pathogenesis, by studying the offspring of Tg19959 mice crossed with MnSOD-overexpressing mice. At 4 mo of age, there was a 2- to 3-fold increase in MnSOD protein levels in Tg19959-MnSOD mice compared to Tg19959 littermates. Tg19959-MnSOD mice also had a 50% increase in catalase protein levels, a 50% decrease in levels of oxidized protein, and a 33% reduction in cortical plaque burden compared to Tg19959 littermates. Spatial memory was impaired and synaptophysin levels were decreased in Tg19959 mice compared to wild-type littermates, but memory and synaptophysin levels were restored to wild-type levels in Tg19959-MnSOD littermates. These benefits occurred without changes in sodium dodecyl sulfate-soluble or formic acid-soluble Abeta pools or Abeta oligomers in Tg19959-MnSOD mice compared to Tg19959 littermates. These data demonstrate that facilitation of the mitochondrial antioxidant response improves resistance to Abeta, slows plaque formation or increases plaque degradation, and markedly attenuates the phenotype in a transgenic AD mouse model.
    Dokumententyp:
    Referenz
    Produkbestellnummer:
    AB5078P
    Produktbezeichnung:
    Anti-Beta-Amyloid 1-42 Antibody

  • Oxidative stress and altered lipid homeostasis in the programming of offspring fatty liver by maternal obesity. 24789994

    Changes in the maternal nutritional environment during fetal development can influence offspring's metabolic risk in later life. Animal models have demonstrated that offspring of diet-induced obese dams develop metabolic complications, including nonalcoholic fatty liver disease. In this study we investigated the mechanisms in young offspring that lead to the development of nonalcoholic fatty liver disease (NAFLD). Female offspring of C57BL/6J dams fed either a control or obesogenic diet were studied at 8 wk of age. We investigated the roles of oxidative stress and lipid metabolism in contributing to fatty liver in offspring. There were no differences in body weight or adiposity at 8 wk of age; however, offspring of obese dams were hyperinsulinemic. Oxidative damage markers were significantly increased in their livers, with reduced levels of the antioxidant enzyme glutathione peroxidase-1. Mitochondrial complex I and II activities were elevated, while levels of mitochondrial cytochrome c were significantly reduced and glutamate dehydrogenase was significantly increased, suggesting mitochondrial dysfunction. Offspring of obese dams also had significantly greater hepatic lipid content, associated with increased levels of PPARγ and reduced triglyceride lipase. Liver glycogen and protein content were concomitantly reduced in offspring of obese dams. In conclusion, offspring of diet-induced obese dams have disrupted liver metabolism and develop NAFLD prior to any differences in body weight or body composition. Oxidative stress may play a mechanistic role in the progression of fatty liver in these offspring.
    Dokumententyp:
    Referenz
    Produkbestellnummer:
    Mehrere
    Produktbezeichnung:
    Mehrere

  • Oxidative stress and inflammation modulate Rev-erbα signaling in the neonatal lung and affect circadian rhythmicity. 24252172

    The response to oxidative stress and inflammation varies with diurnal rhythms. Nevertheless, it is not known whether circadian genes are regulated by these stimuli. We evaluated whether Rev-erbα, a key circadian gene, was regulated by oxidative stress and/or inflammation in vitro and in a mouse model.A unique sequence consisting of overlapping AP-1 and nuclear factor kappa B (NFκB) consensus sequences was identified on the mouse Rev-erbα promoter. This sequence mediates Rev-erbα promoter activity and transcription in response to oxidative stress and inflammation. This region serves as an NrF2 platform both to receive oxidative stress signals and to activate Rev-erbα, as well as an NFκB-binding site to repress Rev-erbα with inflammatory stimuli. The amplitude of the rhythmicity of Rev-erbα was altered by pre-exposure to hyperoxia or disruption of NFκB in a cell culture model of circadian simulation. Oxidative stress overcame the inhibitory effect of NFκB binding on Rev-erbα transcription. This was confirmed in neonatal mice exposed to hyperoxia, where hyperoxia-induced lung Rev-erbα transcription was further increased with NFκB disruption. Interestingly, this effect was not observed in similarly exposed adult mice.These data provide novel mechanistic insights into how key circadian genes are regulated by oxidative stress and inflammation in the neonatal lung.Rev-erbα transcription and circadian oscillation are susceptible to oxidative stress and inflammation in the neonate. Due to Rev-erbα's role in cellular metabolism, this could contribute to lung cellular function and injury from inflammation and oxidative stress.
    Dokumententyp:
    Referenz
    Produkbestellnummer:
    Mehrere
    Produktbezeichnung:
    Mehrere

  • Caveosomal Oxidative Stress Causes Src-p21ras Activation and Lysine 63 TRAF6 Protein Polyubiquitination in Iron-induced M1 Hepatic Macrophage Activation. 22829592

    Proinflammatory M1 activation of hepatic macrophages (HM) is critical in pathogenesis of hepatitis, but its mechanisms are still elusive. Our earlier work demonstrates the role of ferrous iron (Fe(2+)) as a pathogen-associated molecular pattern-independent agonist for activation of IκB kinase (IKK) and NF-κB in HM via activation and interaction of p21(ras), transforming growth factor β-activated kinase-1 (TAK1), and phosphatidylinositol 3-kinase (PI3K) in caveosomes. However, iron-induced signaling upstream of these kinases is not known. Here we show that Fe(2+) induces generation of superoxide anion (O(2)()) in endosomes, reduces protein-tyrosine phosphatase (PTP) activity, and activates Src at 2∼10 min of Fe(2+) addition to rat primary HM culture. Superoxide dismutase (SOD) blocks O(2)() generation, PTP inhibition, and Src activation. Fe(2+)-induced p21(ras) activity is abrogated with the Src inhibitor PP2 and SOD. Fe(2+) stimulates Lys(63)-linked polyubiquitination (polyUb) of TRAF6 in caveosomes, and a dominant negative K63R mutant of ubiquitin or SOD prevents iron-induced TRAF6 polyUb and TAK1 activation. These results demonstrate that Fe(2+)-generated O(2)() mediates p21(ras) and TAK1 activation via PTP inhibition and Lys(63)-polyUb of TRAF6 in caveosomes for proinflammatory M1 activation in HM.
    Dokumententyp:
    Referenz
    Produkbestellnummer:
    17-131
    Produktbezeichnung: