The protonophore CCCP induces mitochondrial permeability transition without cytochrome c release in human osteosarcoma cells.
Mitochondrial permeability transition (MPT) and cytochrome c redistribution from mitochondria are two events associated with apoptosis. We investigated whether an MPT event obligatorily leads to cytochrome c release in vivo. We have previously shown that treatment of human osteosarcoma cells with the protonophore m-chlorophenylhydrazone (CCCP) for 6 h induces MPT and mitochondrial swelling without significant cell death. Here we demonstrate that release of cytochrome c does not occur and the cells remain viable even after 72 h of treatment with CCCP. Bax is not mobilized to mitochondria under these conditions. However, subsequent exposure of CCCP-treated cells to etoposide or staurosporine for 48 h results in rapid cell death and cytochrome c release that is accompanied by Bax association with mitochondria, demonstrating competency of these mitochondria to release cytochrome c with additional triggers. Our findings suggest that MPT is not a sufficient condition, in itself, to effect cytochrome c release.
Lim
M L
ML
Department of Biochemistry and Molecular Biology, P.O. Box 13D, Monash University, 3800, Clayton, Vic., Australia.
Minamikawa
T
T
Nagley
P
P
D001859:Bone Neoplasms / Q000201:enzymology* / Q000473:pathology; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology*; D002463:Cell Membrane Permeability / Q000187:drug effects*; D003574:Cytochrome c Group / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D008928:Mitochondria / Q000187:drug effects*; D012516:Osteosarcoma / Q000201:enzymology* / Q000473:pathology; D014407:Tumor Cells, Cultured
D003574:Cytochrome c Group; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone