title: The repair function of the multifunctional DNA repair/redox protein APE1 is neuroprotective after ionizing radiation.
abstract: Although exposure to ionizing radiation (IR) can produce significant neurotoxicity, the mechanisms mediating this toxicity remain to be determined. Previous studies using neurons isolated from the central nervous system show that IR produces reactive oxygen species and oxidative DNA damage in those cells. Because the base excision DNA repair pathway repairs single-base modifications caused by ROS, we asked whether manipulating this pathway by altering APE1 expression would affect radiation-induced neurotoxicity. In cultures of adult hippocampal and sensory neurons, IR produces DNA damage as measured by phosphorylation of histone H2A.X and results in dose-dependent cell death. In isolated sensory neurons, we demonstrate for the first time that radiation decreases the capsaicin-evoked release of the neuropeptide CGRP. Reducing APE1 expression in cultured cells augments IR-induced neurotoxicity, whereas overexpressing APE1 is neuroprotective. Using lentiviral constructs with a neuronal specific promoter that selectively expresses APE1s different functions in neurons, we show that selective expression of the DNA repair competent (redox inactive) APE1 constructs in sensory neurons resurrects cell survival and neuronal function, whereas use of DNA-repair deficient (redox active) constructs is not protective. Use of an APE1 redox-specific inhibitor, APX3330, also facilitates neuronal protection against IR-induced toxicity. These results demonstrate for the first time that the repair function of APE1 is required to protect both hippocampal and DRG neuronal cultures--specifically neuronal cells--from IR-induced damage, while the redox activity of APE1 does not appear to be involved.
authors: Department of Pharmacology & Toxicology, Indiana University School of Medicine, 635 Barnhill Drive Room MSA401, Indianapolis, IN 46202, USA.
authors: Michael R
authors: MR
authors: Vasko
authors: Chunlu
authors: C
authors: Guo
authors: Eric L
authors: EL
authors: Thompson
authors: Mark R
authors: MR
authors: Kelley
mesh_terms: D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects; D002478:Cells, Cultured; D004249:DNA Damage / Q000528:radiation effects*; D004260:DNA Repair; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015870:Gene Expression; D005786:Gene Expression Regulation / Q000187:drug effects / Q000528:radiation effects; D008297:Male; D018696:Neuroprotective Agents / Q000494:pharmacology; D009928:Organ Specificity / Q000235:genetics; D010084:Oxidation-Reduction; D011401:Promoter Regions, Genetic / Q000235:genetics; D011839:Radiation, Ionizing; D051381:Rats; D017207:Rats, Sprague-Dawley; D011984:Sensory Receptor Cells / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects*
chemical_list: D004791:Enzyme Inhibitors; D018696:Neuroprotective Agents; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D015740:Calcitonin Gene-Related Peptide