Two pathways for tBID-induced cytochrome c release from rat brain mitochondria: BAK- versus BAX-dependence.
The mechanisms of truncated BID (tBID)-induced Cyt c release from non-synaptosomal brain mitochondria were examined. Addition of tBID to mitochondria induced partial Cyt c release which was inhibited by anti-BAK antibodies, implicating BAK. Immunoblotting showed the presence of BAK, but not BAX, in brain mitochondria. tBID did not release Cyt c from rat liver mitochondria, which lacked both BAX and BAK. This indicated that tBID did not act independently of BAX and BAK. tBID plus monomeric BAX produced twice as much Cyt c release as did tBID or oligomeric BAX alone. Neither tBID alone nor in combination with BAX induced mitochondrial swelling. In both cases Cyt c release was insensitive to cyclosporin A plus ADP, inhibitors of the mitochondrial permeability transition (mPT). Recombinant Bcl-xL inhibited Cyt c release induced by tBID alone or in combination with monomeric BAX. Koenig's polyanion, an inhibitor of VDAC, suppressed tBID-induced Cyt c release from brain mitochondria mediated by BAK but not by BAX. Thus, tBID can induce mPT-independent Cyt c release from brain mitochondria by interacting with exogenous BAX and/or with endogenous BAK that may involve VDAC. In contrast, neither adenylate kinase nor Smac/DIABLO was released from isolated rat brain mitochondria via BAK or BAX.
Brustovetsky
Nickolay
N
Department of Neuroscience, University of Minnesota, Minneapolis 55455, USA.
Dubinsky
Janet M
JM
Antonsson
Bruno
B
Jemmerson
Ronald
R
D000818:Animals; D051023:BH3 Interacting Domain Death Agonist Protein; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D002352:Carrier Proteins / Q000494:pharmacology*; D003574:Cytochrome c Group / Q000378:metabolism*; D004338:Drug Combinations; D008297:Male; D008565:Membrane Proteins / Q000502:physiology*; D051379:Mice; D008815:Mice, Inbred Strains; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism; D008933:Mitochondrial Swelling; D010539:Permeability / Q000187:drug effects; D011518:Proto-Oncogene Proteins / Q000502:physiology*; D019253:Proto-Oncogene Proteins c-bcl-2; D051381:Rats; D017207:Rats, Sprague-Dawley; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein
D051023:BH3 Interacting Domain Death Agonist Protein; C494773:Bak1 protein, mouse; C494774:Bak1 protein, rat; C494827:Bax protein, mouse; C494828:Bax protein, rat; C494815:Bid protein, mouse; C494816:Bid protein, rat; D002352:Carrier Proteins; D003574:Cytochrome c Group; D004338:Drug Combinations; D008565:Membrane Proteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein