title: Bcl-2 protects against hyperoxia-induced apoptosis through inhibition of the mitochondria-dependent pathway.
abstract: Bcl-2 is an antiapoptotic molecule that prevents oxidative stress damage and cell death. We investigated the possible protective mechanisms mediated by Bcl-2 during hyperoxia-induced cell death in L929 cells. In these cells, hyperoxia promoted apoptosis without DNA fragmentation. Overexpression of Bcl-2 significantly protected cells from oxygen-induced apoptosis, as shown by measurement of lactate dehydrogenase release, quantification of apoptotic nuclei, and detection of Annexin-V-positive cells. Bcl-2 partially prevented mitochondrial damage and interfered with the mitochondrial proapoptotic signaling pathway: it reduced Bax translocation to mitochondria, decreased the release of cytochrome c, and inhibited caspase 3 activation. However, treatment with the caspase inhibitor Z-VAD.fmk failed to rescue the cells from death, indicating that protection provided by Bcl-2 was due not only to caspase inhibition. Bcl-2 also prevented the release of mitochondrial apoptotic inducing factor, a mediator of caspase-independent apoptosis, correlating with the absence of oligonucleosomal DNA fragmentation. In addition, Bcl-2-overexpressing cells showed significantly higher intracellular amounts of glutathione after 72 h of oxygen exposure. In conclusion, our results demonstrate that the overexpression of Bcl-2 is able to prevent hyperoxia-induced cell death, by affecting mitochondria-dependent apoptotic pathways and increasing intracellular antioxidant compounds.
authors.affiliation: Department of Pediatrics, Medical School, University of Geneva, Switzerland.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Métrailler-Ruchonnet
authors.forename: Alessandra
authors.initials: A
authors.lastname: Pagano
authors.forename: Stephanie
authors.initials: S
authors.lastname: Carnesecchi
authors.forename: Christiane
authors.initials: C
authors.lastname: Ody
authors.forename: Yves
authors.initials: Y
authors.lastname: Donati
authors.forename: Constance
authors.initials: C
authors.lastname: Barazzone Argiroffo
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D015153:Blotting, Western; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D002460:Cell Line; D045304:Cytochromes c / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D018496:Hyperoxia / Q000503:physiopathology*; D007150:Immunohistochemistry; D051379:Mice; D008854:Microscopy, Electron; D008928:Mitochondria / Q000502:physiology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000502:physiology*; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D061945:Caspase Inhibitors; D019253:Proto-Oncogene Proteins c-bcl-2; D017382:Reactive Oxygen Species; D000255:Adenosine Triphosphate; D045304:Cytochromes c; D020169:Caspases; D005978:Glutathione