Mammalian polymerase θ promotes alternative NHEJ and suppresses recombination

Nature. 2015 Feb 12;518(7538):254-7. doi: 10.1038/nature14157. Epub 2015 Feb 2.

Abstract

The alternative non-homologous end-joining (NHEJ) machinery facilitates several genomic rearrangements, some of which can lead to cellular transformation. This error-prone repair pathway is triggered upon telomere de-protection to promote the formation of deleterious chromosome end-to-end fusions. Using next-generation sequencing technology, here we show that repair by alternative NHEJ yields non-TTAGGG nucleotide insertions at fusion breakpoints of dysfunctional telomeres. Investigating the enzymatic activity responsible for the random insertions enabled us to identify polymerase theta (Polθ; encoded by Polq in mice) as a crucial alternative NHEJ factor in mammalian cells. Polq inhibition suppresses alternative NHEJ at dysfunctional telomeres, and hinders chromosomal translocations at non-telomeric loci. In addition, we found that loss of Polq in mice results in increased rates of homology-directed repair, evident by recombination of dysfunctional telomeres and accumulation of RAD51 at double-stranded breaks. Lastly, we show that depletion of Polθ has a synergistic effect on cell survival in the absence of BRCA genes, suggesting that the inhibition of this mutagenic polymerase represents a valid therapeutic avenue for tumours carrying mutations in homology-directed repair genes.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Base Sequence
  • Cell Death / genetics
  • Cell Line
  • Chromosome Aberrations
  • Chromosomes, Mammalian / genetics
  • Chromosomes, Mammalian / metabolism*
  • DNA Breaks, Double-Stranded*
  • DNA End-Joining Repair*
  • DNA-Directed DNA Polymerase / deficiency
  • DNA-Directed DNA Polymerase / metabolism*
  • Genes, BRCA1
  • Genes, BRCA2
  • HeLa Cells
  • Humans
  • Mice
  • Poly (ADP-Ribose) Polymerase-1
  • Poly(ADP-ribose) Polymerases / genetics
  • Poly(ADP-ribose) Polymerases / metabolism
  • Rad51 Recombinase / metabolism
  • Recombination, Genetic* / genetics
  • Recombinational DNA Repair / genetics
  • Telomere / genetics*
  • Telomere / metabolism*
  • Translocation, Genetic / genetics

Substances

  • PARP1 protein, human
  • Poly (ADP-Ribose) Polymerase-1
  • Poly(ADP-ribose) Polymerases
  • DNA polymerase theta
  • Rad51 Recombinase
  • DNA-Directed DNA Polymerase

Associated data

  • BioProject/PRJNA269507