A novel adenine nucleotide translocase inhibitor, MT-21, induces cytochrome c release by a mitochondrial permeability transition-independent mechanism.
The release of cytochrome c from mitochondria is a critical step during apoptosis. In order to study this process, we have used a synthetic compound, MT-21, that is able to initiate release of cytochrome c from isolated mitochondria. We demonstrate that MT-21 significantly inhibits ADP transport activity in mitochondria and reduces binding of the adenine nucleotide translocase (ANT) to a phenylarsine oxide affinity matrix. These results suggest that ANT, one of the components of the mitochondrial permeability transition (PT) pore, is the molecular target for MT-21. In agreement with this, the MT-21-induced cytochrome c release was effectively inhibited in the presence of ANT ligands, and MT-21 could dissociate ANT from a complex with a glutathione S-transferase-cyclophilin D fusion protein. Interestingly, we also found that specific inhibitors of ANT such as MT-21 and atractyloside could induce cytochrome c release without mitochondrial swelling and that this event was highly dependent on the presence of Mg(2+). These results suggest that although ANT resides in the mitochondrial inner membrane, specific ANT inhibitors can induce cytochrome c release without having an effect on inner membrane permeability. Therefore, MT-21 can be a powerful tool for studying the mechanism of PT-independent cytochrome c release from mitochondria.
Machida
Kiyotaka
K
Antibiotics Laboratory, RIKEN, Hirosawa 2-1, Saitama 351-0198, Japan.
Hayashi
Yujiro
Y
Osada
Hiroyuki
H
D003001:Cloning, Molecular; D000081406:Peptidyl-Prolyl Isomerase F; D021983:Cyclophilins / Q000737:chemistry / Q000235:genetics; D003574:Cytochrome c Group / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D018922:HL-60 Cells; D006801:Humans; D007473:Ion Channels / Q000502:physiology*; D008274:Magnesium / Q000494:pharmacology; D000226:Mitochondrial ADP, ATP Translocases / Q000037:antagonists & inhibitors* / Q000737:chemistry; D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; D011487:Protein Conformation; D011758:Pyrroles / Q000494:pharmacology*
D000081406:Peptidyl-Prolyl Isomerase F; D003574:Cytochrome c Group; D004791:Enzyme Inhibitors; D007473:Ion Channels; C121809:MT 21; D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; D011758:Pyrroles; D000226:Mitochondrial ADP, ATP Translocases; D021983:Cyclophilins; D008274:Magnesium