RAD52 is required for RNA-templated recombination repair in post-mitotic neurons [DNA and Chromosomes]

It has been long assumed that post-mitotic neurons only utilize the error-prone non-homologous end joining (NHEJ) pathway to repair double strand breaks (DSBs) associated with oxidative damage to DNA, given the inability of non-replicating neuronal DNA to utilize a sister chromatid template in the less error-prone homologous recombination (HR) repair pathway. However, we and others recently have found that active transcription triggers a replication-independent recombinational repair mechanism in the G0/G1 phase of the cell cycle. Here we observed that the HR repair protein RAD52 is recruited to sites of DNA DSBs in terminally differentiated, post-mitotic neurons. This recruitment is dependent upon the presence of a nascent mRNA generated during active transcription, providing evidence that an RNA-templated HR repair mechanism exists in non-dividing, terminally differentiated neurons. This recruitment of RAD52 in neurons is decreased by transcription inhibition. Importantly, we found that high concentrations of amyloid beta (Aβ), a toxic protein associated with Alzheimer's disease (AD), inhibits the expression and DNA damage response of RAD52, potentially leading to a defect in the error-free, RNA-templated HR repair mechanism. This study shows a novel RNA dependent repair mechanism of DSBs in postmitotic neurons, and demonstrates that defects in this pathway may contribute to neuronal genomic instability and consequent neurodegenerative phenotypes such as seen in AD.

from # All Medicine by Alexandros G. Sfakianakis via Alexandros G.Sfakianakis on Inoreader http://ift.tt/2j6exxD
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