title: Mitochondrial cytochrome c release is caspase-dependent and does not involve mitochondrial permeability transition in didemnin B-induced apoptosis.
abstract: Permeability transition, and a subsequent drop in mitochondrial membrane potential (DeltaPsi(m)), have been suggested to be mechanisms by which cytochrome c is released from the mitochondria into the cytosol during apoptosis. Furthermore, a drop in DeltaPsi(m) has been suggested to be an obligate early step in the apoptotic pathway. Didemnin B, a branched cyclic peptolide described to have immunosuppressive, anti-tumour, and anti-viral properties, induces rapid apoptosis in a range of mammalian cell lines. Induction of apoptosis by didemnin B in cultured human pro-myeloid HL-60 cells is the fastest and most complete ever described with all cells being apoptotic after 3 h of treatment. By utilizing the system of didemnin B-induced apoptosis in HL-60 cells, and the potent inhibitors of mitochondrial permeability transition, cyclosporin A and bongkrekic acid, we show that permeability transition as determined by changes in DeltaPsi(m) and mitochondrial Ca2+ fluxing, is not a requirement for apoptosis or cytochrome c release. In this system, changes in mitochondrial membrane potential and cytochrome c release are shown to be dependent on caspase activation, and to occur concurrently with the release of caspase-9 from mitochondria, genomic DNA fragmentation and apoptotic body formation.
authors.affiliation: Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, Monash University, Melbourne, Australia, 3800.
authors.forename: D R
authors.initials: DR
authors.lastname: Grubb
authors.forename: J D
authors.initials: JD
authors.lastname: Ly
authors.forename: F
authors.initials: F
authors.lastname: Vaillant
authors.forename: K L
authors.initials: KL
authors.lastname: Johnson
authors.forename: A
authors.initials: A
authors.lastname: Lawen
mesh_terms: D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D001865:Bongkrekic Acid / Q000494:pharmacology; D002051:Burkitt Lymphoma / Q000473:pathology; D020013:Calcium Signaling; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism / Q000502:physiology*; D016572:Cyclosporine / Q000494:pharmacology; D003574:Cytochrome c Group / Q000378:metabolism*; D053938:DNA Fragmentation; D047630:Depsipeptides; D004789:Enzyme Activation; D018922:HL-60 Cells / Q000187:drug effects / Q000648:ultrastructure; D006801:Humans; D007425:Intracellular Membranes / Q000187:drug effects / Q000502:physiology*; D007473:Ion Channels; D008545:Melanoma / Q000473:pathology; D008564:Membrane Potentials / Q000187:drug effects; D008565:Membrane Proteins / Q000378:metabolism; D008928:Mitochondria / Q000187:drug effects / Q000201:enzymology*; D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; D010456:Peptides, Cyclic / Q000494:pharmacology*; D010539:Permeability / Q000187:drug effects; D019284:Thapsigargin / Q000494:pharmacology; D014407:Tumor Cells, Cultured
chemical_list: D003574:Cytochrome c Group; D047630:Depsipeptides; D007473:Ion Channels; D008565:Membrane Proteins; D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; D010456:Peptides, Cyclic; D001865:Bongkrekic Acid; C030051:didemnins; D019284:Thapsigargin; D016572:Cyclosporine; C506433:CASP9 protein, human; D053453:Caspase 9; D020169:Caspases