Metalloporphyrin-based superoxide dismutase mimic attenuates the nuclear translocation of apoptosis-inducing factor and the subsequent DNA fragmentation after permanent focal cerebral ischemia in mice.
OBJECTIVE
Recently, apoptosis- inducing factor (AIF), a mitochondrial proapoptotic protein, and its nuclear translocation have been reported in caspase-independent neuronal apoptosis. In this study, we investigated the contribution of reactive oxygen species (ROS) to the nuclear translocation of AIF and the subsequent DNA fragmentation after permanent focal cerebral ischemia (pFCI) using manganese tetrakis (4-benzoic acid) porphyrin (MnTBAP), which mimics mitochondrial superoxide dismutase.


METHODS
Adult male ICR mice were subjected to pFCI by intraluminal suture blockade of the middle cerebral artery. Immunohistochemistry and Western blot analysis were performed. Large-scale DNA fragmentation was evaluated by pulse field gel electrophoresis, and apoptotic cell death was quantified. MnTBAP was injected into the ventricle to determine whether the removal of ROS contributes to AIF translocation and the subsequent DNA fragmentation.


RESULTS
Western blot analysis showed that the nuclear translocation of AIF occurred as early as 2 hours after pFCI. AIF translocation was not blocked by a pan-caspase inhibitor. MnTBAP-treated mice had attenuated AIF translocation and blocked large-scale DNA fragmentation. Caspase-3 activity was similarly inhibited between the pan-caspase inhibitor- and MnTBAP-treated mice, but the amount of apoptosis-associated DNA fragmentation in the MnTBAP-treated mice was less than in the pan-caspase inhibitor-treated mice (P<0.001).


CONCLUSIONS
These results suggest that the MnTBAP, a mitochondrial O2- scavenger, may attenuate the caspase-independent nuclear translocation of AIF after pFCI and subsequent apoptosis-associated DNA fragmentation.
Lee
Byung I
BI
Department of Neurology, Brain Korea 21 Project for Medical Science, College of Medicine, Yonsei University, Seoul, Korea.
Chan
Pak H
PH
Kim
Gyung W
GW
D000818:Animals; D051033:Apoptosis Inducing Factor / Q000235:genetics* / Q000378:metabolism*; D015153:Blotting, Western; D002545:Brain Ischemia / Q000188:drug therapy / Q000378:metabolism*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D053938:DNA Fragmentation / Q000187:drug effects*; D005455:Fluorescent Antibody Technique; D066298:In Vitro Techniques; D008297:Male; D008665:Metalloporphyrins / Q000494:pharmacology*; D051379:Mice; D008813:Mice, Inbred ICR; D018384:Oxidative Stress; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000378:metabolism; D014178:Translocation, Genetic / Q000235:genetics*
D051033:Apoptosis Inducing Factor; D008665:Metalloporphyrins; C494830:AIFM1 protein, mouse; D017382:Reactive Oxygen Species; C097284:manganese(III)-tetrakis(4-benzoic acid)porphyrin; D013482:Superoxide Dismutase; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases