Caspase-dependent alteration of the ADP/ATP translocator triggers the mitochondrial permeability transition which is not required for the low-potassium-dependent apoptosis of cerebellar granule cells.
We investigated ADP/ATP exchange mediated by the adenine nucleotide translocator and opening of the mitochondrial permeability transition pore in homogenates from cerebellar granule cells en route to apoptosis induced by low potassium. We showed that, in the first 3 h of apoptosis, when maximum cytochrome c release had already occurred, adenine nucleotide translocator function was impaired owing to the action of reactive oxygen species, but no permeability transition pore opening occurred. Over 3-8 h of apoptosis, the permeability transition pore progressively opened, owing to caspase action, and further ADP/ATP translocator impairment occurred. The kinetics of transport and permeability transition pore opening were inversely correlated, both in the absence and presence of inhibitors of antioxidant and proteolytic systems. We conclude that, en route to apoptosis, alteration of the adenine nucleotide translocator occurs, resulting in permeability transition pore opening. This process depends on the action of caspase on pore component(s) other than the ADP/ATP translocator, because no change in either amount or molecular weight of the latter protein was noted during apoptosis, as measured by western blotting. Cell death occurs via apoptosis in the presence of cyclosporin A, the permeability transition pore inhibitor, thus showing that permeability transition pore opening, not needed for cytochrome c release, is also unnecessary for apoptosis to occur.
Atlante
Anna
A
Istituto di Biomembrane e Bioenergetica, Consiglio Nazionale delle Ricerche, Bari, Italy.
Bobba
Antonella
A
de Bari
Lidia
L
Fontana
Fabrizio
F
Calissano
Pietro
P
Marra
Ersilia
E
Passarella
Salvatore
S
D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D020169:Caspases / Q000378:metabolism*; D002478:Cells, Cultured; D002525:Cerebellar Cortex / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D016572:Cyclosporine / Q000494:pharmacology; D045304:Cytochromes c / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D000226:Mitochondrial ADP, ATP Translocases / Q000187:drug effects / Q000378:metabolism*; D051336:Mitochondrial Membranes / Q000187:drug effects / Q000378:metabolism*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D010539:Permeability / Q000187:drug effects; D011191:Potassium Deficiency / Q000378:metabolism* / Q000503:physiopathology; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species
D004791:Enzyme Inhibitors; D017382:Reactive Oxygen Species; D000244:Adenosine Diphosphate; D016572:Cyclosporine; D000255:Adenosine Triphosphate; D045304:Cytochromes c; D000226:Mitochondrial ADP, ATP Translocases; D020169:Caspases