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Cells Devoid (cell + devoid)
Selected AbstractsRole of DNA polymerase , in tolerance of endogenous and exogenous DNA damage in mouse B cellsGENES TO CELLS, Issue 2 2006Akiko Ukai DNA polymerase , (Pol,) is a family A polymerase that contains an intrinsic helicase domain. To investigate the function of Pol, in mammalian cells, we have inactivated its polymerase activity in CH12 mouse B lymphoma cells by targeted deletion of the polymerase core domain that contains the catalytic aspartic acid residue. Compared to parental CH12 cells, mutant cells devoid of Pol, polymerase activity exhibited a slightly reduced growth rate, accompanied by increased spontaneous cell death. In addition, mutant cells showed elevated sensitivity to mitomycin C, cisplatin, etoposide, ,-irradiation and ultraviolet (UV) radiation. Interestingly, mutant cells were more sensitive to the alkylating agent methyl methanesulfonate (MMS) than parental cells. This elevated MMS sensitivity relative to WT cells persisted in the presence of methoxyamine, an inhibitor of the major base excision repair (BER) pathway, suggesting that Pol, is involved in tolerance of MMS through a mechanism that appears to be different from BER. These results reveal an important role for Pol, in preventing spontaneous cell death and in tolerance of not only DNA interstrand cross-links and double strand breaks but also UV adducts and alkylation damage in mammalian lymphocytes. [source] The Legionella pneumophila Dps homolog is regulated by iron and involved in multiple stress toleranceJOURNAL OF BASIC MICROBIOLOGY, Issue S1 2009Ming-jia Yu Abstract Iron homeostasis is essential to almost all organisms. In this study, we identified the putative homolog of the iron-storage protein-encoding gene, dpsL, in the intracellular pathogen Legionella pneumophila and demonstrated its expression under iron-limited conditions and its responses to multiple stresses. Quantitative real-time PCR analysis indicated that the expression of dpsL was enhanced under iron limitation regardless of the growth phase. Compared with the wild-type cells, the cells devoid of dpsL were heat and H2O2 -sensitive. In contrast to the dps mutants of other bacteria, the growth of the dpsL mutant in an iron-deprived medium was delayed but finally reached the same cell density as wild-type cells during the stationary phase of growth. The finding that the dpsL mutant is salt resistant suggested the involvement of DpsL in virulence. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Candida albicans cell surface superoxide dismutases degrade host-derived reactive oxygen species to escape innate immune surveillanceMOLECULAR MICROBIOLOGY, Issue 1 2009Ingrid E. Frohner Summary Mammalian innate immune cells produce reactive oxygen species (ROS) in the oxidative burst reaction to destroy invading microbial pathogens. Using quantitative real-time ROS assays, we show here that both yeast and filamentous forms of the opportunistic human fungal pathogen Candida albicans trigger ROS production in primary innate immune cells such as macrophages and dendritic cells. Through a reverse genetic approach, we demonstrate that coculture of macrophages or myeloid dendritic cells with C. albicans cells lacking the superoxide dismutase (SOD) Sod5 leads to massive extracellular ROS accumulation in vitro. ROS accumulation was further increased in coculture with fungal cells devoid of both Sod4 and Sod5. Survival experiments show that C. albicans mutants lacking Sod5 and Sod4 exhibit a severe loss of viability in the presence of macrophages in vitro. The reduced viability of sod5,/, and sod4,/,sod5,/, mutants relative to wild type is not evident with macrophages from gp91phox,/, mice defective in the oxidative burst activity, demonstrating a ROS-dependent killing activity of macrophages targeting fungal pathogens. These data show a physiological role for cell surface SODs in detoxifying ROS, and suggest a mechanism whereby C. albicans, and perhaps many other microbial pathogens, can evade host immune surveillance in vivo. [source] Plasma membrane NADH-oxidoreductase in cells carrying mitochondrial DNA G11778A mutation and in cells devoid of mitochondrial DNA (,0)BIOFACTORS, Issue 4 2004Safarina G. Malik Abstract The mammalian plasma membrane (PM) NADH-oxidoreductase (PMOR) system is a multi-enzyme complex located in the plasma membrane of all eukaryotic cells, harboring at least two distinct activities, the plasma membrane NADH-ferricyanide reductase and the NADH-oxidase. To assess the behaviour of the two activities of the PMOR system, we measured the NADH-ferricyanide reductase and NADH-oxidase activities in fibroblast cell lines derived from patients carrying a mitochondrial DNA (mtDNA) G11778A mutation. We also measured the two activities in other cell lines, the HL-60 and HeLa (S3) lines, as well as in ,0 cells (cells devoid of mtDNA) generated from those lines and the fibroblast cells. These ,0 cells consequently lack oxidative phosphorylation and rely on anaerobic glycolysis for their ATP need. We have proposed that in ,0 cells, at least in part, up-regulation of the PMOR is a necessity to maintain the NAD+/NADH ratio, and a pre-requisite for cell growth and viability. We show here that the PM NADH-ferricyanide reductase activity was up-regulated in HL-AV2 (HL-60 ,0) cell lines, but not in the other ,0 and mtDNA mutant lines. The plasma membrane NADH oxidase activity was found to be up-regulated in both HL-AV2 and HeLa ,0 cell lines, but not significantly in the fibroblast ,0 and G11778A lines. [source] | ||||||||||