Regulation of DNA double-strand break repair pathway choice

Cell Res. 2008 Jan;18(1):134-47. doi: 10.1038/cr.2007.111.


DNA double-strand breaks (DSBs) are critical lesions that can result in cell death or a wide variety of genetic alterations including large- or small-scale deletions, loss of heterozygosity, translocations, and chromosome loss. DSBs are repaired by non-homologous end-joining (NHEJ) and homologous recombination (HR), and defects in these pathways cause genome instability and promote tumorigenesis. DSBs arise from endogenous sources including reactive oxygen species generated during cellular metabolism, collapsed replication forks, and nucleases, and from exogenous sources including ionizing radiation and chemicals that directly or indirectly damage DNA and are commonly used in cancer therapy. The DSB repair pathways appear to compete for DSBs, but the balance between them differs widely among species, between different cell types of a single species, and during different cell cycle phases of a single cell type. Here we review the regulatory factors that regulate DSB repair by NHEJ and HR in yeast and higher eukaryotes. These factors include regulated expression and phosphorylation of repair proteins, chromatin modulation of repair factor accessibility, and the availability of homologous repair templates. While most DSB repair proteins appear to function exclusively in NHEJ or HR, a number of proteins influence both pathways, including the MRE11/RAD50/NBS1(XRS2) complex, BRCA1, histone H2AX, PARP-1, RAD18, DNA-dependent protein kinase catalytic subunit (DNA-PKcs), and ATM. DNA-PKcs plays a role in mammalian NHEJ, but it also influences HR through a complex regulatory network that may involve crosstalk with ATM, and the regulation of at least 12 proteins involved in HR that are phosphorylated by DNA-PKcs and/or ATM.

Publication types

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

MeSH terms

  • Animals
  • Ataxia Telangiectasia Mutated Proteins
  • Cell Cycle / genetics
  • Cell Cycle / physiology
  • Cell Cycle Proteins / physiology
  • Chromosome Aberrations
  • DNA Breaks, Double-Stranded*
  • DNA Repair / physiology*
  • DNA-Activated Protein Kinase / physiology
  • DNA-Binding Proteins / physiology
  • Eukaryotic Cells / metabolism
  • Genomic Instability
  • Humans
  • Models, Biological
  • Nuclear Proteins / physiology
  • Protein-Serine-Threonine Kinases / physiology
  • Recombination, Genetic / physiology
  • Signal Transduction / genetics*
  • Species Specificity
  • Tumor Suppressor Proteins / physiology
  • Yeasts / genetics


  • Cell Cycle Proteins
  • DNA-Binding Proteins
  • Nuclear Proteins
  • Tumor Suppressor Proteins
  • ATM protein, human
  • Ataxia Telangiectasia Mutated Proteins
  • DNA-Activated Protein Kinase
  • PRKDC protein, human
  • Protein-Serine-Threonine Kinases