XRCC1 protects transcription from toxic PARP1 activity during DNA base excision repair

Genetic defects in the repair of DNA single-strand breaks (SSBs) can result in neurological disease triggered by toxic activity of the single-strand-break sensor protein PARP1. However, the mechanism(s) by which this toxic PARP1 activity triggers cellular dysfunction are unclear. Here we show that human cells lacking XRCC1 fail to rapidly recover transcription following DNA base damage, a phenotype also observed in patient-derived fibroblasts with XRCC1 mutations and Xrcc1−/− mouse neurons. This defect is caused by excessive/aberrant PARP1 activity during DNA base excision repair, resulting from the loss of PARP1 regulation by XRCC1. We show that aberrant PARP1 activity suppresses transcriptional recovery during base excision repair by promoting excessive recruitment and activity of the ubiquitin protease USP3, which as a result reduces the level of monoubiquitinated histones important for normal transcriptional regulation. Importantly, inhibition and/or deletion of PARP1 or USP3 restores transcriptional recovery in XRCC1−/− cells, highlighting PARP1 and USP3 as possible therapeutic targets in neurological disease.

DNA repair enzyme NEIL3 enables a stable neural representation of space by shaping transcription in hippocampal neurons

ABSTRACTDNA repair enzymes are essential for the maintenance of neuronal genome and thereby proper brain functions. NEIL3 is a member of the NEIL family DNA glycosylases initiating oxidative DNA base excision repair. Recent studies show that NEIL3-deficiency leads to impaired spatial performance in mice, decreased adult neurogenesis and altered synaptic composition in the hippocampus. However, it remains elusive how NEIL3 contributes to spatial information coding in hippocampal neurons. Here, we revealed impaired spatial stability in Neil3−/− CA1 place cells, demonstrating a functional interference of NEIL3 with spatial representations. We identified NEIL3-dependent transcriptional changes in response to spatial exploration and defined its regulatory role specifically for NMDA receptor subunits and immediate early genes. Our work demonstrates a non-canonical role of NEIL3 in modulating the functional plasticity of place cells by shaping the neuronal transcriptome, thus sheds light on the molecular determinants enabling a stable neural representation of space.