PT  - JOURNAL ARTICLE
AU  - Miki Fujimura
AU  - Yuiko Morita-Fujimura
AU  - Nobuo Noshita
AU  - Taku Sugawara
AU  - Makoto Kawase
AU  - Pak H. Chan
TI  - The Cytosolic Antioxidant Copper/Zinc-Superoxide Dismutase Prevents the Early Release of Mitochondrial Cytochrome c in Ischemic Brain after Transient Focal Cerebral Ischemia in Mice
AID  - 10.1523/JNEUROSCI.20-08-02817.2000
DP  - 2000 Apr 15
TA  - The Journal of Neuroscience
PG  - 2817--2824
VI  - 20
IP  - 8
4099  - http://www.jneurosci.org/content/20/8/2817.short
4100  - http://www.jneurosci.org/content/20/8/2817.full
SO  - J. Neurosci.2000 Apr 15; 20
AB  - Release of mitochondrial cytochrome c into the cytosol is a critical step in apoptosis. We have reported that early release of cytochrome c in vivo occurs after permanent focal cerebral ischemia (FCI) and is mediated by the mitochondrial antioxidant manganese superoxide dismutase (SOD). However, the role of reactive oxygen species produced after ischemia–reperfusion in the mitochondrial apoptosis process is still unknown, although overexpression of copper/zinc-SOD (SOD1), a cytosolic isoenzyme, protects against ischemia–reperfusion. We now hypothesize that the overexpression of SOD1 also prevents apoptosis after FCI. To address this issue, we examined the subcellular distribution of the cytochrome c protein in both wild-type mice and in SOD1 transgenic (Tg) mice after transient FCI. Cytosolic cytochrome c was detected as early as 2 hr after reperfusion, and correspondingly, mitochondrial cytochrome c was significantly reduced after FCI. Cytosolic cytochrome c was significantly lower in the SOD1 Tg mice compared with wild types 2 (p < 0.0001) and 4 (p < 0.05) hr after FCI. Apaf-1, which interacts with cytochrome c and activates caspases, was constitutively expressed in both groups of animals, with no alteration after FCI. Double staining with cytochrome c immunohistochemistry and terminal deoxynucleotidyl transferase-mediated uridine 5′-triphosphate-biotin nick end labeling showed a spatial relationship between cytosolic cytochrome c expression and DNA fragmentation. A significant amount of DNA laddering was detected 24 hr after ischemia and was reduced in SOD1 Tg mice. These data suggest that SOD1 blocks cytosolic release of cytochrome c and could thereby reduce apoptosis after transient FCI.