Oligomycin and antimycin A prevent nitric oxide-induced apoptosis by blocking cytochrome C leakage.
Nitric oxide (NO) is a potent inducer of apoptosis, and its cytotoxicity is closely related to mitochondrial dysfunction. In this study we investigated the effects of a F0F1-ATPase inhibitor, oligomycin, and a mitochondrial respiratory chain complex III inhibitor, antimycin A, on NO-induced apoptosis. We used a normal rat gastric-epithelium cell line, RGM-1, treated with a pure NO donor, NOC-1 -1-hydroxy-2-oxo-3,3-bis(2-aminoethyl)-1-triazene - in the presence or absence of oligomycin or antimycin A. Changes in the expressions of Bax or Bcl-2 proteins, release of cytochrome C from mitochondria into the cytosol, activation of caspase-3, and changes in the mitochondrial membrane potential (DeltaPsi) were measured with the use of Western blotting, c43 lorimetric assays, and a mitochondrial potential sensor, JC-1 dye. Treatment with NOC-18 induced dose-dependent apoptotic cell death in RGM-1 cells. Cell death was accompanied by mitochondrial depolarization, increases in Bax protein expression and cytochrome C leakage, and, subsequently, caspase-3 activation. Oligomycin and antimycin A prevented NO-induced apoptosis in a dose-dependent fashion by preventing cytochrome C release independent of Bcl-2 expression. However, neither compound affected the up-regulation of Bax protein. On the one hand, oligomycin treatment was not accompanied by a decline in DeltaPsi. On the other hand, antimycin A treatment decreased DeltaPsi regardless of NOC-18 treatment. The findings of this study suggest that various functional molecules that constitute the mitochondrial respiratory chain may contribute to cytochrome C release that occurs during NO-induced apoptosis.
Division of Gastroenterology, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan.
Naohiro
N
Dairaku
Katsuaki
K
Kato
Kennichi
K
Honda
Tomoyuki
T
Koike
Katsunori
K
Iijima
Akira
A
Imatani
Hitoshi
H
Sekine
Shuichi
S
Ohara
Hiroshi
H
Matsui
Tooru
T
Shimosegawa
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D000968:Antimycin A / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D002460:Cell Line; D045304:Cytochromes c / Q000037:antagonists & inhibitors* / Q000378:metabolism; D005753:Gastric Mucosa / Q000166:cytology* / Q000187:drug effects / Q000502:physiology; D009569:Nitric Oxide / Q000494:pharmacology / Q000502:physiology*; D020030:Nitric Oxide Donors / Q000494:pharmacology*; D009573:Nitrites / Q000378:metabolism; D009603:Nitroso Compounds / Q000494:pharmacology*; D009840:Oligomycins / Q000494:pharmacology*; D051381:Rats
C093285:NOC 18; D020030:Nitric Oxide Donors; D009573:Nitrites; D009603:Nitroso Compounds; D009840:Oligomycins; D009569:Nitric Oxide; D000968:Antimycin A; D000255:Adenosine Triphosphate; D045304:Cytochromes c