title: PARP cleavage, DNA fragmentation, and pyknosis during excitotoxin-induced neuronal death.
abstract: Poly(ADP-ribose)polymerase-1 (PARP-1) is a nuclear enzyme activated by DNA breaks and serves a role in DNA repair through the formation of polymers (poly(ADP)ribosylation) at sites of DNA damage. PARP-1 is activated by DNA damage in neurons of the hippocampus and cerebral cortex following excessive exposure to glutamate receptor agonists such as NMDA or kainic acid. In addition, recent studies suggest that degradation of PARP-1 occurs in cells that undergo apoptotic versus nonapoptotic forms of cell death. To investigate this process further, we examined the spatiotemporal aspects of excitotoxic injury in the rodent visual cortex by making focal intracerebral injections of kainic acid. These injections resulted in DNA damage, PARP-1 activation, and neuronal cell death over a 5-day period. Rapid neuronal cell injury assessed by Fluoro-Jade staining appeared within hours, but increased TUNEL staining occurred only after 24 h. A dramatic increase in caspase-3 activity, as well as an increase in the number of neurons containing active caspase-3, peaked 2 days after injury. Last, increased PARP-1 immunoreactivity and PARP-1 cleavage reached peak levels 2 to 3 days after delivering the excitotoxin. These findings suggest that increased caspase-3 activity may regulate the degradation of PARP-1 in subsets of cortical neurons during excitotoxic cell death.
authors.affiliation: Department of Biology and Program in Neuroscience and Behavior, Wesleyan University, Middletown, CT 06459, USA.
authors.forename: Karen L
authors.initials: KL
authors.lastname: Gilliams-Francis
authors.forename: Aurora A
authors.initials: AA
authors.lastname: Quaye
authors.forename: Janice R
authors.initials: JR
authors.lastname: Naegele
mesh_terms: D000818:Animals; D015153:Blotting, Western; D053148:Caspase 3; D020169:Caspases / Q000096:biosynthesis; D016923:Cell Death / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002540:Cerebral Cortex / Q000166:cytology / Q000187:drug effects; D053938:DNA Fragmentation / Q000502:physiology*; D018690:Excitatory Amino Acid Agonists / Q000633:toxicity*; D005456:Fluorescent Dyes; D020287:In Situ Nick-End Labeling; D007608:Kainic Acid / Q000633:toxicity*; D008297:Male; D016202:N-Methylaspartate / Q000633:toxicity*; D009410:Nerve Degeneration / Q000473:pathology; D010641:Phenotype; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; D011506:Proteins / Q000378:metabolism*; D051381:Rats; D020318:Rats, Long-Evans; D013049:Spectrin / Q000378:metabolism
chemical_list: D018690:Excitatory Amino Acid Agonists; D005456:Fluorescent Dyes; D011506:Proteins; D013049:Spectrin; D016202:N-Methylaspartate; C499322:Parp1 protein, rat; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases; D007608:Kainic Acid