Oxidative stress-induced calcium signalling in Aspergillus nidulans.
The effects of oxidative stress on levels of calcium ion (Ca(2+)) in Aspergillus nidulans were measured using strains expressing aequorin in the cytoplasm (Aeq(cyt)) and mitochondria (Aeq(mt)). When oxidative stress was induced by exposure to 10-mM H(2)O(2), the mitochondrial calcium response (Ca(mt)(2+)) was greater than the change in cytoplasmic calcium (Ca(c)(2+)). The Ca(mt)(2+) response to H(2)O(2) was dose dependent, while the increase in [Ca(c)(2+)] did not change with increasing H(2)O(2). The increase in both [Ca(c)(2+)] and [Ca(mt)(2+)] in response to oxidative stress was enhanced by exposure of cells to Ca(2+). The presence of chelator in the external medium only partially inhibited the Ca(mt)(2+) and Ca(c)(2+) responses to oxidative stress. Reagents that alter calcium fluxes had varied effects on the Ca(mt)(2+) response to peroxide. Ruthenium red blocked the increase in [Ca(mt)(2+)], while neomycin caused an even greater increase in [Ca(mt)(2+)]. Treatment with ruthenium red and neomycin had no effect on the Ca(c)(2+) response. Bafilomycin A and oligomycin had no effect on either the mitochondrial or cytoplasmic response. Inhibitors of both voltage-regulated calcium channels and intracellular calcium release channels inhibited the Ca(2+)-dependent component of the Ca(mt)(2+) response to oxidative stress. We conclude that the more significant Ca(2+) response to oxidative stress occurs in the mitochondria and that both intracellular and extracellular calcium pools can contribute to the increases in [Ca(c)(2+)] and [Ca(mt)(2+)] induced by oxidative stress.
Greene
Vilma
V
Department of Biological Sciences, St. John's University, 8000 Utopia Parkway, Jamaica, NY 11439, USA.
Cao
Hong
H
Schanne
Francis A X
FA
Bartelt
Diana C
DC
D000331:Aequorin / Q000032:analysis; D001233:Aspergillus nidulans / Q000187:drug effects / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020013:Calcium Signaling; D002138:Calibration; D002614:Chelating Agents / Q000494:pharmacology; D003593:Cytoplasm / Q000378:metabolism; D004533:Egtazic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008163:Luminescent Measurements; D008928:Mitochondria / Q000378:metabolism; D018384:Oxidative Stress
D002121:Calcium Channel Blockers; D002614:Chelating Agents; D000331:Aequorin; D004533:Egtazic Acid; C039877:5,5'-difluoro-1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; D006861:Hydrogen Peroxide