title: Non-homologous DNA end joining in the mature rat brain.
abstract: Recent evidence suggests that DNA double strand breaks (DSBs) are introduced in neurons during the course of normal development, and that repair of such DSBs is essential for neuronal survival. Here we describe a non-homologous DNA end joining (NHEJ) system in the adult rat brain that may be used to repair DNA DSBs. In the brain NHEJ system, blunt DNA ends are joined with lower efficiency than cohesive or non-matching protruding ends. Moreover, brain NHEJ is blocked by DNA ligase inhibitors or by dATP and can occur in the presence or absence of exogenously added ATP. Comparison of NHEJ activities in several tissues showed that brain and testis share similar mechanisms for DNA end joining, whereas the activity in thymus seems to utilize different mechanisms than in the nervous system. The developmental profile of brain NHEJ showed increasing levels of activity after birth, peaking at postnatal day 12 and then gradually decreasing along with age. Brain distribution analysis in adult animals showed that NHEJ activity is differentially distributed among different regions. We suggest that the DNA NHEJ system may be utilized in the postnatal brain for the repair of DNA double strand breaks introduced within the genome in the postnatal brain.
authors.affiliation: Department of Biology, University of Puerto Rico, San Juan, Puerto Rico.
authors.forename: Keqin
authors.initials: K
authors.lastname: Ren
authors.forename: Sandra
authors.initials: S
authors.lastname: Peña de Ortiz
mesh_terms: D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D000375:Aging / Q000378:metabolism; D000818:Animals; D015139:Blotting, Southern; D001921:Brain / Q000378:metabolism*; D001923:Brain Chemistry; D002474:Cell-Free System / Q000737:chemistry / Q000378:metabolism; D002540:Cerebral Cortex / Q000737:chemistry / Q000378:metabolism; D019457:Chromosome Breakage; D004247:DNA / Q000378:metabolism*; D011088:DNA Ligases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D004260:DNA Repair / Q000187:drug effects / Q000502:physiology*; D004587:Electrophoresis, Agar Gel; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006624:Hippocampus / Q000737:chemistry / Q000378:metabolism; D008297:Male; D009928:Organ Specificity; D051381:Rats; D020318:Rats, Long-Evans; D014020:Tissue Extracts / Q000737:chemistry / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D014020:Tissue Extracts; D000255:Adenosine Triphosphate; D004247:DNA; D011088:DNA Ligases