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Caspase‐3 is not activated in seizure‐induced neuronal necrosis with internucleosomal DNA cleavage
Author(s) -
Fujikawa Denson G.,
Ke Xingrao,
Trinidad Rosen B.,
Shinmei Steve S.,
Wu Aiguo
Publication year - 2002
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.2002.01152.x
Subject(s) - dna laddering , tunel assay , apoptotic dna fragmentation , terminal deoxynucleotidyl transferase , microbiology and biotechnology , status epilepticus , biology , dna fragmentation , caspase 3 , apoptosis , biochemistry , epilepsy , programmed cell death , neuroscience
A caspase‐3‐activated DNase produces internucleosomal DNA cleavage (DNA laddering). We determined whether caspase‐3 is activated by lithium–pilocarpine‐induced status epilepticus in six brain regions with necrosis‐induced DNA laddering. The thymuses of adult rats given methamphetamine or normal saline were used as controls for apoptosis. Some 6–8 h after methamphetamine treatment, thymocytes showed apoptosis by electron‐microscopic examination, positive terminal deoxynucleotidyl transferase dUTP nick‐end labeling (TUNEL), DNA laddering, cleavage of caspase‐3 into its active p17 subunit, active caspase‐3 immunoreactivity, and a 25‐fold increase in caspase‐3‐like activity. Six hours after SE, necrotic neurons by electron‐microscopic examination in hippocampus, amygdala and piriform, entorhinal and frontal cortices showed no TUNEL and no DNA laddering. Twenty‐four hours after seizures, most necrotic neurons were negative for TUNEL, some were positive, but all regions showed DNA laddering. However, 6 and 24 h after seizures, active caspase‐3 immunoreactivity was negative, caspase‐3‐like activity did not increase, and western blot analysis failed to show the p17 subunit. In addition, 24 h after seizures,microdialytic perfusion of carbobenzoxy‐valyl‐alanyl‐aspartyl ( O ‐methylester) fluoromethylketone was not neuroprotective. Thus, caspase‐3 is not activated in brain regions with seizure‐induced neuronal necrosis with DNA laddering. Either caspase‐activated DNase is activated by another enzyme, or a caspase‐independent DNase is responsible for the DNA cleavage.