BRCA1-Ku80 protein interaction enhances end-joining fidelity of chromosomal double-strand breaks in the G1 phase of the cell cycle

J Biol Chem. 2013 Mar 29;288(13):8966-76. doi: 10.1074/jbc.M112.412650. Epub 2013 Jan 23.

Abstract

Quality control of DNA double-strand break (DSB) repair is vital in preventing mutagenesis. Non-homologous end-joining (NHEJ), a repair process predominant in the G1 phase of the cell cycle, rejoins DSBs either accurately or with errors, but the mechanisms controlling its fidelity are poorly understood. Here we show that BRCA1, a tumor suppressor, enhances the fidelity of NHEJ-mediated DSB repair and prevents mutagenic deletional end-joining through interaction with canonical NHEJ machinery during G1. BRCA1 binds and stabilizes Ku80 at DSBs through its N-terminal region, promotes precise DSB rejoining, and increases cellular resistance to radiation-induced DNA damage in a G1 phase-specific manner. These results suggest that BRCA1, as a central player in genome integrity maintenance, ensures high fidelity repair of DSBs by not only promoting homologous recombination repair in G2/M phase but also facilitating fidelity of Ku80-dependent NHEJ repair, thus preventing deletional end-joining of chromosomal DSBs during G1.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Antigens, Nuclear / metabolism*
  • BRCA1 Protein / metabolism*
  • Cell Cycle
  • Chromatin Immunoprecipitation
  • DNA / analysis
  • DNA Breaks, Double-Stranded
  • DNA Repair
  • DNA-Binding Proteins / metabolism*
  • G1 Phase
  • Gene Deletion
  • Glutathione Transferase / metabolism
  • HEK293 Cells
  • Humans
  • Ku Autoantigen
  • Mutagenesis
  • Nuclear Proteins / metabolism
  • Protein Binding
  • Recombination, Genetic
  • Signal Transduction

Substances

  • Antigens, Nuclear
  • BRCA1 Protein
  • BRCA1 protein, human
  • DNA-Binding Proteins
  • Nuclear Proteins
  • DNA
  • Glutathione Transferase
  • Xrcc6 protein, human
  • Ku Autoantigen