Protection against hydrogen peroxide cytotoxicity in rat-1 fibroblasts provided by the oncoprotein Bcl-2: maintenance of calcium homoeostasis is secondary to the effect of Bcl-2 on cellular glutathione.
The oncoprotein Bcl-2 protects cells against apoptosis, but the exact molecular mechanism that underlies this function has not yet been identified. Studying H2O2-induced cell injury in Rat-1 fibroblast cells, we observed that Bcl-2 had a protective effect against the increase in cytosolic calcium concentration and subsequent cell death. Furthermore, overexpression of Bcl-2 resulted in an alteration of cellular glutathione status: the total amount of cellular glutathione was increased by about 60% and the redox potential of the cellular glutathione pool was maintained in a more reduced state during H2O2 exposure compared with non-Bcl-2-expressing controls. In our cytotoxicity model, disruption of cellular glutathione homoeostasis closely correlated with the pathological elevation of cytosolic calcium concentration. Stabilization of the glutathione pool by Bcl-2, N-acetylcysteine or glucose delayed the cytosolic calcium increase and subsequent cell death, whereas depletion of glutathione by dl-buthionine-(S, R)-sulphoximine, sensitized Bcl-2-transfected cells towards cytosolic calcium increase and cell death. We therefore suggest that the protection exerted by Bcl-2 against H2O2-induced cytosolic calcium elevation and subsequent cell death is secondary to its effect on the cellular glutathione metabolism.
Rimpler
M M
MM
Institut für Physiologische Chemie, Universitätsklinikum Essen, Hufelandstrasse 55, D-45122 Essen, Germany.
Rauen
U
U
Schmidt
T
T
Möröy
T
T
de Groot
H
H
D000111:Acetylcysteine / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000378:metabolism; D000634:Aminoquinolines / Q000494:pharmacology; D000818:Animals; D019328:Buthionine Sulfoximine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D016923:Cell Death / Q000187:drug effects; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects*; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D016257:Fura-2; D005947:Glucose / Q000494:pharmacology; D005978:Glutathione / Q000378:metabolism*; D006706:Homeostasis / Q000187:drug effects*; D006861:Hydrogen Peroxide / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D010084:Oxidation-Reduction / Q000187:drug effects; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000502:physiology*; D011720:Pyrazoles; D051381:Rats; D013997:Time Factors; D014162:Transfection
D000634:Aminoquinolines; D019253:Proto-Oncogene Proteins c-bcl-2; D011720:Pyrazoles; D019328:Buthionine Sulfoximine; C059597:monochlorobimane; D000255:Adenosine Triphosphate; D006861:Hydrogen Peroxide; D005978:Glutathione; D005947:Glucose; C035739:Quin2; D002118:Calcium; D016257:Fura-2; D000111:Acetylcysteine