Bcl-2 protects against apoptosis induced by antimycin A and bongkrekic acid without restoring cellular ATP levels.
Several studies indicate that mitochondrial ATP production as well as ADP/ATP exchange across mitochondrial membranes are impaired during apoptosis. We investigated whether Bcl-2 could protect against cell death under conditions in which ATP metabolism is inhibited. Inhibition of ATP production using antimycin A (AA) (complex III inhibition) combined with inhibition of ADP/ATP exchange by bongkrekic acid (BA) (adenine nucleotide translocator (ANT) inhibition) induced a sharp decrease in total cellular ATP in FL5.12 parental cells (to 35% of untreated controls after 24 h of incubation). Within 24 and 48 h, 38% and 75% of the cells had died, respectively. However, in stably transfected FL5.12 Bcl-2 subclones, no cell death occurred under these experimental conditions. Similar results were obtained with Jurkat and Bcl-2 overexpressing Jurkat cells. Total cellular ATP levels were equally affected in FL5.12 Bcl-2 overexpressing cells and FL5.12 parental cells. This indicates that Bcl-2 overexpressing cells are able to survive with very low cellular ATP content. Furthermore, Bcl-2 did not protect against cell death by restoring ATP levels. This suggests that, under these conditions, Bcl-2 acts by inhibiting the signalling cascade triggered by the inhibitors that would normally lead to apoptosis.
de Graaf
Aniek O
AO
Central Hematology Laboratory/Department of Hematology, University Medical Center Nijmegen, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands. a.degraaf@chl.azn.nl
Meijerink
Jules P P
JP
van den Heuvel
Lambert P
LP
DeAbreu
Ronney A
RA
de Witte
Theo
T
Jansen
Joop H
JH
Smeitink
Jan A M
JA
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D000968:Antimycin A / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D001865:Bongkrekic Acid / Q000494:pharmacology*; D002460:Cell Line; D004249:DNA Damage; D005434:Flow Cytometry; D006801:Humans; D019169:Jurkat Cells; D051379:Mice; D008928:Mitochondria / Q000187:drug effects; D010101:Oxygen Consumption; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000502:physiology*
D019253:Proto-Oncogene Proteins c-bcl-2; D001865:Bongkrekic Acid; D000968:Antimycin A; D000255:Adenosine Triphosphate