TY - JOUR
T1 - Manganese superoxide dismutase mediates the early release of mitochondrial cytochrome C and subsequent DNA fragmentation after permanent focal cerebral ischemia in mice
AU - Fujimura, Miki
AU - Morita-Fujimura, Yuiko
AU - Kawase, Makoto
AU - Copin, Jean Christophe
AU - Calagui, Bernard
AU - Epstein, Charles J.
AU - Chan, Pak H.
PY - 1999/5/1
Y1 - 1999/5/1
N2 - Recent studies have shown that release of mitochondrial cytochrome c is a critical step in the apoptosis process. We have reported that cytosolic redistribution of cytochrome c in vivo occurred after transient focal cerebral ischemia (FCI) in rats and preceded the peak of DNA fragmentation. Although the involvement of reactive oxygen species in the cytosolic redistribution of cytochrome c in vitro has been suggested, the detailed mechanism by which cytochrome c release is mediated in vivo has not yet been established. Also, the role of mitochondrial oxidative stress in cytochrome c release is unknown. These issues can be addressed using knock-out mutants that are deficient in the level of the mitochondrial antioxidant manganese superoxide dismutase (Mn-SOD). In this study we examined the subcellular distribution of the cytochrome c protein in both wild-type mice and heterozygous knock-outs of the Mn-SOD gene (Sod2 -/+) after permanent FCI, in which apoptosis is assumed to participate. Cytosolic cytochrome c was detected as early as 1 hr after ischemia, and correspondingly, mitochondrial cytochrome c showed a significant reduction 2 hr after ischemia (p < 0.01). Cytosolic accumulation of cytochrome c was significantly higher in Sod2 -/+ mice compared with wild-type animals (p < 0.05). N-benzyloxycarbonyl-valala- asp-fluoromethyl ketone (z-VAD.FMK), a nonselective caspase inhibitor, did not affect cytochrome c release after ischemia. A significant amount of DNA laddering was detected 24 hr after ischemia and increased in Sod2 -/+ mice. These data suggest that Mn-SOD blocks cytosolic release of cytochrome c and could thereby reduce apoptosis after permanent FCI.
AB - Recent studies have shown that release of mitochondrial cytochrome c is a critical step in the apoptosis process. We have reported that cytosolic redistribution of cytochrome c in vivo occurred after transient focal cerebral ischemia (FCI) in rats and preceded the peak of DNA fragmentation. Although the involvement of reactive oxygen species in the cytosolic redistribution of cytochrome c in vitro has been suggested, the detailed mechanism by which cytochrome c release is mediated in vivo has not yet been established. Also, the role of mitochondrial oxidative stress in cytochrome c release is unknown. These issues can be addressed using knock-out mutants that are deficient in the level of the mitochondrial antioxidant manganese superoxide dismutase (Mn-SOD). In this study we examined the subcellular distribution of the cytochrome c protein in both wild-type mice and heterozygous knock-outs of the Mn-SOD gene (Sod2 -/+) after permanent FCI, in which apoptosis is assumed to participate. Cytosolic cytochrome c was detected as early as 1 hr after ischemia, and correspondingly, mitochondrial cytochrome c showed a significant reduction 2 hr after ischemia (p < 0.01). Cytosolic accumulation of cytochrome c was significantly higher in Sod2 -/+ mice compared with wild-type animals (p < 0.05). N-benzyloxycarbonyl-valala- asp-fluoromethyl ketone (z-VAD.FMK), a nonselective caspase inhibitor, did not affect cytochrome c release after ischemia. A significant amount of DNA laddering was detected 24 hr after ischemia and increased in Sod2 -/+ mice. These data suggest that Mn-SOD blocks cytosolic release of cytochrome c and could thereby reduce apoptosis after permanent FCI.
KW - Apoptosis
KW - Caspase
KW - Cerebral ischemia
KW - Cytochrome c
KW - Manganese superoxide dismutase
KW - Mitochondrial injury
KW - Reactive oxygen species
UR - http://www.scopus.com/inward/record.url?scp=0033135367&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0033135367&partnerID=8YFLogxK
U2 - 10.1523/jneurosci.19-09-03414.1999
DO - 10.1523/jneurosci.19-09-03414.1999
M3 - Article
C2 - 10212301
AN - SCOPUS:0033135367
VL - 19
SP - 3414
EP - 3422
JO - Journal of Neuroscience
JF - Journal of Neuroscience
SN - 0270-6474
IS - 9
ER -