CHANGES IN DNA REPAIR EXPRESSION FOLLOWING STATUS EPILEPTICUS
Abstract number :
2.065
Submission category :
Year :
2003
Submission ID :
2078
Source :
www.aesnet.org
Presentation date :
12/6/2003 12:00:00 AM
Published date :
Dec 1, 2003, 06:00 AM
Authors :
Samantha L. Crowe, Dawn Selby, Timothy J. Jorgensen, Karen Gale, Alexei Kondratyev Interdisciplinary Program in Neuroscience, Georgetown University Medical Center, Washington, DC; Department of Pharmacology, Georgetown University Medical Center, Washingto
Status epilepticus (SE) results in excitotoxic cellular injury including DNA damage. If not repaired, DNA damage may cause cell death in vulnerable populations. Although DNA damage following seizure-induced injury has been examined extensively, there is a paucity of data regarding the extent to which DNA repair may compensate following such insults. We hypothesized that the regulation of DNA repair mechanisms may be an important determinant of vulnerability to seizure-induced cell death. In this study, we used a microarray to analyze changes in expression of genes associated with DNA damage and repair following SE in rats.
SE was induced in male Sprague-Dawley rats by kainic acid (12.5 mg/kg, i.p.) and terminated after a 2 hr duration with diazepam (30 mg/kg, i.p.). Rhinal cortex was collected at 4, 8, and 20 hr following SE termination, and total RNA was extracted and processed following the protocol outlined in the SuperArray non-rad gene manual. Samples were hybridized on the SuperArray mouse DNA Damage Signaling Pathways gene array containing 96 mouse genes.
Several genes exhibited at least a two-fold increase in the aftermath of SE. At 4hr post SE termination, this was observed in 26 genes, at 8 hr in 17 genes, and at 20hr in 22 genes. Activated genes included several DNA damage responsive genes including the growth arrest and DNA-damage-inducible gene 45 (Gadd45), proliferating cell nuclear antigen (PCNA), and MDM-2 which were all upregulated at 4 hr and persisted at elevated levels up to 20 hr post SE termination. Genes from several DNA repair pathways were also upregulated at all three time points following SE including members of the transcriptional coupled repair pathway (CSB and XPG) and the base excision repair pathway (uracil DNA glycosylase (UNG)). Ku 80, a member of the non-homologous end-joining pathway (which is responsible for double strand break repair) was upregulated at 4 and 8 hr but returned to control levels by 20 hr post SE termination.
Our results indicate that DNA damage responsive genes and DNA repair machinery are activated rapidly during or immediately following SE. This raises the possibility that the net impact of SE on cell death is a function of both induction of apoptotic mechanisms and compensatory repair mechanisms. Strategies aimed at augmenting DNA repair may provide a novel target for therapeutic interventions.
[Supported by: NIH grants NS 20576, MH 02040, NS 041231, and by the Epilepsy Foundation]