title: Potentiation of apoptosis by mitochondria in a cell-free system.
abstract: Using a cell-free system, we show that rat liver mitochondria, but not mitochondrial extracts, potentiated apoptosis triggered by cytosols derived from apoptotic cells. Apoptosis potentiated by mitochondria appeared to be inhibited by caspase 3 but not by caspase 1 inhibitors. A cytosolic caspase-3-like activity was increased by the addition of mitochondria to apoptotic cytosols; the latter activation was inhibited by the addition of bcl-2. Chelation of calcium by EGTA significantly and specifically inhibited the apoptosis potentiated by mitochondria as well as the increase of caspase-3-like activity. The incubation of mitochondria with apoptotic cytosols led to the release of cytochrome c, this latter phenomenon being inhibited by EGTA. Calcium or cytochrome c and dATP, however, did not reproduce the mitochondrial potentiation in the absence of the organelle. Thus, mitochondria can initiate and potentiate apoptosis through similar but not identical mechanisms.
authors.affiliation: Unité INSERM 419, Nantes, France.
authors.forename: P
authors.initials: P
authors.lastname: Juin
authors.forename: K
authors.initials: K
authors.lastname: Tremblais
authors.forename: M T
authors.initials: MT
authors.lastname: LeCabellec
authors.forename: M
authors.initials: M
authors.lastname: Grégoire
authors.forename: K
authors.initials: K
authors.lastname: Meflah
authors.forename: F M
authors.initials: FM
authors.lastname: Vallette
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D002118:Calcium / Q000502:physiology; D053148:Caspase 3; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D002474:Cell-Free System / Q000502:physiology; D002478:Cells, Cultured; D002614:Chelating Agents / Q000494:pharmacology; D016572:Cyclosporine / Q000494:pharmacology; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D003574:Cytochrome c Group / Q000378:metabolism; D004533:Egtazic Acid / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D008099:Liver / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D008930:Mitochondria, Liver / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000494:pharmacology; D051381:Rats
chemical_list: D061945:Caspase Inhibitors; D002614:Chelating Agents; D015853:Cysteine Proteinase Inhibitors; D003574:Cytochrome c Group; D019253:Proto-Oncogene Proteins c-bcl-2; D004533:Egtazic Acid; D016572:Cyclosporine; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases; D002118:Calcium