Modulation of the Omi/HtrA2 signaling pathway after transient focal cerebral ischemia in mouse brains that overexpress SOD1.
Omi/HtrA2 is a novel protein that contributes to the regulation of mitochondrial apoptosis after a variety of cell death stimuli in vitro and is thought to negatively control the inhibitor-of-apoptosis protein (IAP) family. However, the Omi/HtrA2 pathway remains unknown in apoptotic neuronal cell death in vivo. To examine the role of the Omi/HtrA2 pathway and its relationship to oxidative stress after reperfusion following cerebral ischemia, we used a transient focal cerebral ischemia (tFCI) model in copper/zinc-superoxide dismutase (SOD1) transgenic mice and wild-type mice. We evaluated the link between the Omi/HtrA2 pathway and the caspase cascade reaction after tFCI by administration of a pan-caspase inhibitor, Z-VAD-FMK. We observed the time-dependent expression of Omi/HtrA2 and its binding to X-chromosome-linked IAP (Omi/XIAP) by immunohistochemistry, Western blotting and coimmunoprecipitation. Translocation of Omi/HtrA2 into the cytosolic space was detected during the early period after tFCI and was not affected by Z-VAD-FMK administration, but it was prevented by SOD1 overexpression. Coimmunoprecipitation revealed that Omi/XIAP transiently increased and that it was prevented by SOD1 overexpression. These results suggest that the Omi/HtrA2 pathway may play an important role in the progress of apoptotic neuronal cell death and that overexpression of SOD1 may attenuate this apoptotic cell death by preventing the Omi/HtrA2 cell signaling pathway.
Department of Neurosurgery and Program in Neurosciences, Stanford University School of Medicine, Stanford, CA 94305-5487, USA.
Atsushi
A
Saito
Takeshi
T
Hayashi
Shuzo
S
Okuno
Tatsuro
T
Nishi
Pak H
PH
Chan
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D015153:Blotting, Western / Q000379:methods; D001921:Brain / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D005455:Fluorescent Antibody Technique / Q000379:methods; D000074923:High-Temperature Requirement A Serine Peptidase 2; D006801:Humans; D047468:Immunoprecipitation / Q000379:methods; D002546:Ischemic Attack, Transient / Q000378:metabolism*; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D024101:Mitochondrial Proteins; D009687:Nuclear Proteins / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D010617:Phenanthridines; D011506:Proteins / Q000378:metabolism; D015424:Reperfusion / Q000379:methods; D012697:Serine Endopeptidases / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism*; D000072105:Superoxide Dismutase-1; D013997:Time Factors; D051636:X-Linked Inhibitor of Apoptosis Protein
D000590:Amino Acid Chloromethyl Ketones; D015853:Cysteine Proteinase Inhibitors; D024101:Mitochondrial Proteins; D009687:Nuclear Proteins; D010617:Phenanthridines; D011506:Proteins; C000606290:SOD1 protein, human; D051636:X-Linked Inhibitor of Apoptosis Protein; C496866:XIAP protein, human; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; C058428:hydroethidine; C000606291:Sod1 protein, mouse; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1; D012697:Serine Endopeptidases; C000615914:HTRA2 protein, human; D000074923:High-Temperature Requirement A Serine Peptidase 2; C000615915:Htra2 protein, mouse; C505407:CASP3 protein, human; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases; D010100:Oxygen