Abstract
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.
Publication types
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Comparative Study
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Amino Acid Chloromethyl Ketones / pharmacology
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Animals
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Blotting, Western / methods
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Brain / cytology
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Brain / drug effects
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Brain / metabolism*
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Caspase 3
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Caspases / metabolism
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Cysteine Proteinase Inhibitors / pharmacology
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Cytosol / drug effects
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Cytosol / metabolism
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Fluorescent Antibody Technique / methods
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High-Temperature Requirement A Serine Peptidase 2
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Humans
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Immunoprecipitation / methods
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Ischemic Attack, Transient / metabolism*
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Male
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Mice
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Mice, Transgenic
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Mitochondria / drug effects
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Mitochondria / metabolism
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Mitochondrial Proteins
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Nuclear Proteins / metabolism
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Oxygen / metabolism
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Phenanthridines
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Proteins / metabolism
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Reperfusion / methods
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Serine Endopeptidases / metabolism*
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Signal Transduction / physiology*
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Superoxide Dismutase / genetics
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Superoxide Dismutase / metabolism*
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Superoxide Dismutase-1
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Time Factors
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X-Linked Inhibitor of Apoptosis Protein
Substances
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Amino Acid Chloromethyl Ketones
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Cysteine Proteinase Inhibitors
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Mitochondrial Proteins
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Nuclear Proteins
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Phenanthridines
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Proteins
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SOD1 protein, human
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X-Linked Inhibitor of Apoptosis Protein
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XIAP protein, human
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benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone
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hydroethidine
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Sod1 protein, mouse
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Superoxide Dismutase
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Superoxide Dismutase-1
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Serine Endopeptidases
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HTRA2 protein, human
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High-Temperature Requirement A Serine Peptidase 2
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Htra2 protein, mouse
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CASP3 protein, human
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Casp3 protein, mouse
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Caspase 3
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Caspases
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Oxygen