title: Glutathione peroxidase-1 protects from CD95-induced apoptosis.
abstract: Through the induction of apoptosis, CD95 plays a crucial role in the immune response and the elimination of cancer cells. Ligation of CD95 receptor activates a complex signaling network that appears to implicate the generation of reactive oxygen species (ROS). This study investigated the place of ROS production in CD95-mediated apoptosis and the role of the antioxidant enzyme glutathione peroxidase-1 (GPx1). Anti-CD95 antibodies triggered an early generation of ROS in human breast cancer T47D cells that was blocked by overexpression of GPx1 and inhibition of initiator caspase activation. Enforced expression of GPx1 also resulted in inhibition of CD95-induced effector caspase activation, DNA fragmentation, and apoptotic cell death. Resistance to CD95-mediated apoptosis was not due to an increased expression of anti-apoptotic molecules and could be reversed by glutathione-depleting agents. In addition, whereas the anti-apoptotic protein Bcl-xL prevented CD95-induced apoptosis in MCF-7 cells, it did not inhibit the early ROS production. Moreover, Bcl-xL but not GPx1 overexpression could suppress the staurosporine-induced late generation of ROS and subsequent cell death. Altogether, these findings suggest that GPx1 functions upstream of the mitochondrial events to inhibit the early ROS production and apoptosis induced by CD95 ligation. Finally, transgenic mice overexpressing GPx1 were partially protected from the lethal effect of anti-CD95, underlying the importance of peroxide formation (and GPx1) in CD95-triggered apoptosis.
authors.affiliation: INSERM U466, Laboratoire de Biochimie Médicale, Centre Hospitalier Universitaire de Rangueil, Toulouse Cedex 9, France.
authors.forename: Valerie
authors.initials: V
authors.lastname: Gouaze
authors.forename: Nathalie
authors.initials: N
authors.lastname: Andrieu-Abadie
authors.forename: Olivier
authors.initials: O
authors.lastname: Cuvillier
authors.forename: Sophie
authors.initials: S
authors.lastname: Malagarie-Cazenave
authors.forename: Marie-Francoise
authors.initials: MF
authors.lastname: Frisach
authors.forename: Marc-Edouard
authors.initials: ME
authors.lastname: Mirault
authors.forename: Thierry
authors.initials: T
authors.lastname: Levade
mesh_terms: D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D001943:Breast Neoplasms; D020169:Caspases / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D053938:DNA Fragmentation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic; D005979:Glutathione Peroxidase / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D014162:Transfection; D014407:Tumor Cells, Cultured; D051020:bcl-X Protein; D019014:fas Receptor / Q000502:physiology*; D000094765:Glutathione Peroxidase GPX1
chemical_list: C494811:BCL2L1 protein, human; D004791:Enzyme Inhibitors; D019253:Proto-Oncogene Proteins c-bcl-2; D017382:Reactive Oxygen Species; D011994:Recombinant Proteins; D051020:bcl-X Protein; D019014:fas Receptor; D005979:Glutathione Peroxidase; D020169:Caspases; D000094765:Glutathione Peroxidase GPX1; C000722067:GPX1 protein, human