Formation of the Apaf-1/cytochrome c complex precedes activation of caspase-9 during seizure-induced neuronal death.
In this study we examine the in vivo formation of the Apaf-1/cytochrome c complex and activation of caspase-9 following limbic seizures in the rat. Seizures were elicited by unilateral intraamygdala microinjection of kainic acid to induce death of CA3 neurons within the hippocampus of the rat. Apaf-1 was found to interact with cytochrome c within the injured hippocampus 0-24 h following seizures by co-immunoprecipitation analysis and immunohistochemistry demonstrated Apaf-1/cytochrome c co-localization. Cleavage of caspase-9 was detected approximately 4 h following seizure cessation within ipsilateral hippocampus and was accompanied by increased cleavage of the substrate Leu-Glu-His-Asp-p-nitroanilide (LEHDpNA) and subsequent strong caspase-9 immunoreactivity within neurons exhibiting DNA fragmentation. Finally, intracerebral infusion of z-LEHD-fluoromethyl ketone increased numbers of surviving CA3 neurons. These data suggest seizures induce formation of the Apaf-1/cytochrome c complex prior to caspase-9 activation and caspase-9 may be a potential therapeutic target in the treatment of brain injury associated with seizures.
Henshall
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Robert S. Dow Neurobiology Laboratories, Legacy Research, Portland, OR 97232, USA. dhenshall@DowNeurobiology.org
Bonislawski
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Skradski
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Araki
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Lan
J Q
JQ
Schindler
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Meller
R
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Simon
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RP
D000818:Animals; D053477:Apoptotic Protease-Activating Factor 1; D001921:Brain / Q000378:metabolism; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism*; D016923:Cell Death; D003574:Cytochrome c Group / Q000737:chemistry* / Q000378:metabolism; D053938:DNA Fragmentation; D004789:Enzyme Activation; D007150:Immunohistochemistry; D046911:Macromolecular Substances; D009474:Neurons / Q000378:metabolism* / Q000473:pathology*; D009842:Oligopeptides / Q000378:metabolism / Q000494:pharmacology; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism; D051381:Rats; D012640:Seizures / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology
C506594:Apaf1 protein, rat; D053477:Apoptotic Protease-Activating Factor 1; D003574:Cytochrome c Group; D046911:Macromolecular Substances; D009842:Oligopeptides; D011506:Proteins; C403754:benzyloxycarbonyl-leucyl-glutamyl-histidyl-aspartic acid fluoromethyl ketone; C506435:Casp9 protein, rat; D053453:Caspase 9; D020169:Caspases