title: Exogenous oxidative stress induces Ca2+ release in the yeast Saccharomyces cerevisiae.
abstract: The Ca(2+) -dependent response to oxidative stress caused by H(2)O(2) or tert-butylhydroperoxide (tBOOH) was investigated in Saccharomyces cerevisiae cells expressing transgenic cytosolic aequorin, a Ca(2+) -dependent photoprotein. Both H(2)O(2) and tBOOH induced an immediate and short-duration cytosolic Ca(2+) increase that depended on the concentration of the stressors. Sublethal doses of H(2)O(2) induced Ca(2+) entry into the cytosol from both extracellular and vacuolar sources, whereas lethal H(2)O(2) shock mobilized predominantly the vacuolar Ca(2+). Sublethal and lethal tBOOH shocks induced mainly the influx of external Ca(2+), accompanied by a more modest vacuolar contribution. Ca(2+) transport across the plasma membrane did not necessarily involve the activity of the Cch1p/Mid1p channel, whereas the release of vacuolar Ca(2+) into the cytosol required the vacuolar channel Yvc1p. In mutants lacking the Ca(2+) transporters, H(2)O(2) or tBOOH sensitivity correlated with cytosolic Ca(2+) overload. Thus, it appears that under H(2)O(2)-induced or tBOOH-induced oxidative stress, Ca(2+) mediates the cytotoxic effect of the stressors and not the adaptation process.
authors.affiliation: Faculty of Chemistry, University of Bucharest, Bucharest, Romania.
authors.forename: Claudia-Valentina
authors.initials: CV
authors.lastname: Popa
authors.forename: Ioana
authors.initials: I
authors.lastname: Dumitru
authors.forename: Lavinia L
authors.initials: LL
authors.lastname: Ruta
authors.forename: Andrei F
authors.initials: AF
authors.lastname: Danet
authors.forename: Ileana C
authors.initials: IC
authors.lastname: Farcasanu
mesh_terms: D000331:Aequorin / Q000235:genetics / Q000502:physiology; D002118:Calcium / Q000378:metabolism*; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D017931:DNA Primers; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007700:Kinetics; D009154:Mutation; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology*; D016133:Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D015290:Second Messenger Systems / Q000502:physiology; D014617:Vacuoles / Q000187:drug effects / Q000502:physiology; D020122:tert-Butylhydroperoxide / Q000494:pharmacology
chemical_list: D017931:DNA Primers; D011994:Recombinant Proteins; D000331:Aequorin; D020122:tert-Butylhydroperoxide; D006861:Hydrogen Peroxide; D002118:Calcium