MSH2-MSH3 promotes DNA end resection during homologous recombination and blocks polymerase theta-mediated end-joining through interaction with SMARCAD1 and EXO1

Nucleic Acids Res. 2023 Jun 23;51(11):5584-5602. doi: 10.1093/nar/gkad308.


DNA double-strand break (DSB) repair via homologous recombination is initiated by end resection. The extent of DNA end resection determines the choice of the DSB repair pathway. Nucleases for end resection have been extensively studied. However, it is still unclear how the potential DNA structures generated by the initial short resection by MRE11-RAD50-NBS1 are recognized and recruit proteins, such as EXO1, to DSB sites to facilitate long-range resection. We found that the MSH2-MSH3 mismatch repair complex is recruited to DSB sites through interaction with the chromatin remodeling protein SMARCAD1. MSH2-MSH3 facilitates the recruitment of EXO1 for long-range resection and enhances its enzymatic activity. MSH2-MSH3 also inhibits access of POLθ, which promotes polymerase theta-mediated end-joining (TMEJ). Collectively, we present a direct role of MSH2-MSH3 in the initial stages of DSB repair by promoting end resection and influencing the DSB repair pathway by favoring homologous recombination over TMEJ.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line
  • DNA / metabolism
  • DNA Breaks, Double-Stranded
  • DNA End-Joining Repair
  • DNA Helicases / metabolism
  • DNA Repair*
  • Exodeoxyribonucleases* / metabolism
  • Homologous Recombination
  • Humans
  • MutS Homolog 2 Protein* / metabolism
  • MutS Homolog 3 Protein* / metabolism


  • DNA
  • Exodeoxyribonucleases
  • MutS Homolog 2 Protein
  • MSH2 protein, human
  • MSH3 protein, human
  • EXO1 protein, human
  • SMARCAD1 protein, human
  • DNA Helicases
  • MutS Homolog 3 Protein