Browsing by MeSH term "Catalase"
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Publication A novel family of dehydrin-like proteins is involved in stress response in the human fungal pathogen Aspergillus fumigatus(American Society for Cell Biology (ASCB), 2011-06-01) Wong Sak Hoi, Joanne; Lamarre, Claude; Beau, Rémi; Meneau, Isabelle; Berepiki, Adokiye; Barre, Annick; Mellado, Emilia; Read, Nick D; Latgé, Jean-PaulDuring a search for genes controlling conidial dormancy in Aspergillus fumigatus, two dehydrin-like genes, DprA and DprB, were identified. The deduced proteins had repeated stretches of 23 amino acids that contained a conserved dehydrin-like protein (DPR) motif. Disrupted DprAΔ mutants were hypersensitive to oxidative stress and to phagocytic killing, whereas DprBΔ mutants were impaired in osmotic and pH stress responses. However, no effect was observed on their pathogenicity in our experimental models of invasive aspergillosis. Molecular dissection of the signaling pathways acting upstream showed that expression of DprA was dependent on the stress-activated kinase SakA and the cyclic AMP-protein kinase A (cAMP-PKA) pathways, which activate the bZIP transcription factor AtfA, while expression of DprB was dependent on the SakA mitogen-activated protein kinase (MAPK) pathway, and the zinc finger transcription factor PacC. Fluorescent protein fusions showed that both proteins were associated with peroxisomes and the cytosol. Accordingly, DprA and DprB were important for peroxisome function. Our findings reveal a novel family of stress-protective proteins in A. fumigatus and, potentially, in filamentous ascomycetes.Publication Capsule enlargement in Cryptococcus neoformans confers resistance to oxidative stress suggesting a mechanism for intracellular survival(Wiley, 2008-10) Zaragoza, Oscar; Chrisman, Cara J; Castelli, Maria Victoria; Frases, Susana; Cuenca-Estrella, Manuel; Rodriguez-Tudela, Juan Luis; Casadevall, Arturo; Ministerio de Educación y Ciencia (España); Instituto de Salud Carlos IIICryptococcus neoformans is a facultative intracellular pathogen. The most distinctive feature of C. neoformans is a polysaccharide capsule that enlarges depending on environmental stimuli. The mechanism by which C. neoformans avoids killing during phagocytosis is unknown. We hypothesized that capsule growth conferred resistance to microbicidal molecules produced by the host during infection, particularly during phagocytosis. We observed that capsule enlargement conferred resistance to reactive oxygen species produced by H(2)O(2) that was not associated with a higher catalase activity, suggesting a new function for the capsule as a scavenger of reactive oxidative intermediates. Soluble capsular polysaccharide protected C. neoformans and Saccharomyces cerevisiae from killing by H(2)O(2). Acapsular mutants had higher susceptibility to free radicals. Capsular polysaccharide acted as an antioxidant in the nitroblue tetrazolium (NBT) reduction coupled to beta-nicotinamide adenine dinucleotide (NADH)/phenazine methosulfate (PMS) assay. Capsule enlargement conferred resistance to antimicrobial peptides and the antifungal drug Amphotericin B. Interestingly, the capsule had no effect on susceptibility to azoles and increased susceptibility to fluconazole. Capsule enlargement reduced phagocytosis by environmental predators, although we also noticed that in this system, starvation of C. neoformans cells produced resistance to phagocytosis. Our results suggest that capsular enlargement is a mechanism that enhances C. neoformans survival when ingested by phagocytic cells.Publication Effects of Docosahexaenoic Supplementation and In Vitro Vitamin C on the Oxidative and Inflammatory Neutrophil Response to Activation(Hindawi, 2015) Capó Fiol, Xavier; Martorell, Miquel; Soldevila Verdeguer, Carla; Tur, Josep A; Pons, AntoniWe studied the effects of diet supplementation with docosahexaenoic (DHA) and in vitro vitamin C (VitC) at physiological concentrations on oxidative and inflammatory neutrophil response to phorbol myristate acetate (PMA). Fifteen male footballers ingested a beverage enriched with DHA or a placebo for 8 weeks in a randomized double-blind study. Neutrophils were isolated from blood samples collected in basal conditions at the end of nutritional intervention. Neutrophils were cultured for 2 hours at 37 degrees C in (a) control media, (b) media with PMA, and (c) media with PMA + VitC. PMA induces neutrophil degranulation with increased extracellular myeloperoxidase and catalase activities, nitric oxide production, expression of the inflammatory genes cyclooxygenase-2, nuclear factor kappa beta, interleukin 8 and tumor necrosis factor alpha, and interleukin 6 production. DHA diet supplementation boosts the exit of CAT from neutrophils but moderates the degranulation of myeloperoxidase granules induced by PMA. VitC facilitates azurophilic degranulation of neutrophils and increases gene expression of myeloperoxidase induced by PMA. VitC and DHA diet supplementation prevent PMA effects on inflammatory gene expression, although together they do not produce additional effects. DHA diet supplementation enhances antioxidant defences and anti-inflammatory neutrophil response to in vitro PMA activation. VitC facilitates neutrophil degranulation but prevents an inflammatory response to PMA.Publication Oxidative Stress in Drug-Induced Liver Injury (DILI): From Mechanisms to Biomarkers for Use in Clinical Practice(Multidisciplinary Digital Publishing Institute (MDPI), 2021-03-05) Villanueva-Paz, Marina; Morán, Laura; López-Alcántara, Nuria; Freixo, Cristiana; Andrade, Raúl J.; Lucena, M Isabel; Cubero, Francisco Javier; [Villanueva-Paz,M; Andrade,RJ; Lucena,MI] Unidad de Gestión Clínica de Gastroenterología, Servicio de Farmacología Clínica, Instituto de Investigación Biomédica de Málaga-IBIMA, Hospital Universitario Virgen de la Victoria, Universidad de Málaga, CIBERehd, Málaga, Spain. [Morán,L; López-Alcántara,N; Cubero,FJ] Department of Immunology, Ophthalmology and ENT, Complutense University School of Medicine, Madrid, Spain. [Morán,L] Health Research Institute Gregorio Marañón (IiSGM), Madrid, Spain. [Freixo,C] CINTESIS, Center for Health Technology and Services Research, do Porto University School of Medicine, Porto, Portugal. [Cubero,FJ] 12 de Octubre Health Research Institute (imas12), Madrid, Spain.Idiosyncratic drug-induced liver injury (DILI) is a type of hepatic injury caused by an uncommon drug adverse reaction that can develop to conditions spanning from asymptomatic liver laboratory abnormalities to acute liver failure (ALF) and death. The cellular and molecular mechanisms involved in DILI are poorly understood. Hepatocyte damage can be caused by the metabolic activation of chemically active intermediate metabolites that covalently bind to macromolecules (e.g., proteins, DNA), forming protein adducts-neoantigens-that lead to the generation of oxidative stress, mitochondrial dysfunction, and endoplasmic reticulum (ER) stress, which can eventually lead to cell death. In parallel, damage-associated molecular patterns (DAMPs) stimulate the immune response, whereby inflammasomes play a pivotal role, and neoantigen presentation on specific human leukocyte antigen (HLA) molecules trigger the adaptive immune response. A wide array of antioxidant mechanisms exists to counterbalance the effect of oxidants, including glutathione (GSH), superoxide dismutase (SOD), catalase, and glutathione peroxidase (GPX), which are pivotal in detoxification. These get compromised during DILI, triggering an imbalance between oxidants and antioxidants defense systems, generating oxidative stress. As a result of exacerbated oxidative stress, several danger signals, including mitochondrial damage, cell death, and inflammatory markers, and microRNAs (miRNAs) related to extracellular vesicles (EVs) have already been reported as mechanistic biomarkers. Here, the status quo and the future directions in DILI are thoroughly discussed, with a special focus on the role of oxidative stress and the development of new biomarkers.