Manganese Superoxide Dismutase Affects Cytochrome c Release and Caspase-9 Activation After Transient Focal Cerebral Ischemia in Mice.
Release of cytochrome c from mitochondria to cytosol is a critical step in the mitochondrial-dependent signaling pathways of apoptosis. The authors have reported that manganese superoxide dismutase (Mn-SOD) attenuated cytochrome c release and apoptotic cell death after focal cerebral ischemia (FCI). To investigate downstream to the cytochrome c-dependent pathway, the authors examined caspase-9 activation after transient FCI by immunohistochemistry and Western blotting in both wild-type and Sod2 -/+ mice. Mice were subjected to 60 minutes of middle cerebral artery occlusion followed by 1, 2, 4, or 24 hours of reperfusion. Two hours after reperfusion, cytochrome c and caspase-9 were observed in the cytosol and significantly increased in Sod2 -/+ mutants compared with wild-type mice as shown by Western blotting. Immunofluorescent double labeling for cytochrome c and caspase-9 showed cytosolic cytochrome c 1 hour after transient FCI. Cleaved caspase-9 first appeared in the cytosol at 2 hours and colocalized with cytochrome c. Terminal deoxynucleotidyl transferase-mediated uridine 5;-triphosphate-biotin nick and labeling (TUNEL) showed significant increase of positive cells in Sod2 -/+ mice compared with the wild-type in the cortex, but not in the caudate putamen. The current study revealed Mn-SOD might affect cytochrome c translocation and downstream caspase activation in the mitochondrial-dependent cell death pathway after transient FCI.
Noshita
N
N
Department of Neurosurgery, Department of Neurology and Neurological Sciences, and Program in Neurosciences, Stanford University School of Medicine, Stanford, California, U.S.A.
Sugawara
T
T
Fujimura
M
M
Morita-Fujimura
Y
Y
Chan
P H
PH
D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D001921:Brain / Q000201:enzymology* / Q000648:ultrastructure; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism*; D003574:Cytochrome c Group / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D053938:DNA Fragmentation; D004789:Enzyme Activation; D005455:Fluorescent Antibody Technique; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D002546:Ischemic Attack, Transient / Q000201:enzymology* / Q000473:pathology; D051379:Mice; D018345:Mice, Knockout; D008928:Mitochondria / Q000378:metabolism; D013482:Superoxide Dismutase / Q000172:deficiency / Q000235:genetics / Q000502:physiology*
D003574:Cytochrome c Group; D013482:Superoxide Dismutase; C506434:Casp9 protein, mouse; D053453:Caspase 9; D020169:Caspases