Journal
BRAIN RESEARCH BULLETIN
Volume 73, Issue 1-3, Pages 48-54Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.brainresbull.2007.02.001
Keywords
nonhomologous end joining; double strand breaks; DNA repair; neuron; aging
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DNA double strand break (DSB) represents a potentially lethal form of DNA damage. Reports suggest that DSBs are introduced in neurons during the course of normal development, and repair of such DSBs is essential for neuronal survival. The molecular mechanisms of DSB repair by nonhomologous end joining (NHEJ) have been described in several cell types. The present study describes age-related NHEJ activity in the isolated neurons from rat cerebral cortex. Cell-free extracts prepared from rat cortical neurons support efficient NHEJ of linearized plasmid DNA in an in vitro DSB repair assay. End joining efficiency of young neurons is dependent on DNA end structure. A linear plasmid with blunt ends was joined less efficiently by the neuronal extracts than the cohesive or non-matching protruding DNA ends. NHEJ in neurons was blocked by the DNA-PKcs inhibitor wortmannin, and dNTP, and could occur in the absence of exogenously added ATP. The end joining process in young rat neurons is nonfaithful. In vitro NHEJ activity was considerably lower in adult brain, and neurons from old brain failed to support significant end joining. The age-dependent profile of neuronal NHEJ indicates that neurons in postnatal brain utilize error-prone NHEJ to repair DNA double strand breaks accumulated within the genome and this activity declines gradually with age. (C) 2007 Elsevier Inc. All rights reserved.
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