Vertebrate POLQ and POLbeta cooperate in base excision repair of oxidative DNA damage

Mol Cell. 2006 Oct 6;24(1):115-25. doi: 10.1016/j.molcel.2006.07.032.


Base excision repair (BER) plays an essential role in protecting cells from mutagenic base damage caused by oxidative stress, hydrolysis, and environmental factors. POLQ is a DNA polymerase, which appears to be involved in translesion DNA synthesis (TLS) past base damage. We disrupted POLQ, and its homologs HEL308 and POLN in chicken DT40 cells, and also created polq/hel308 and polq/poln double mutants. We found that POLQ-deficient mutants exhibit hypersensitivity to oxidative base damage induced by H(2)O(2), but not to UV or cisplatin. Surprisingly, this phenotype was synergistically increased by concomitant deletion of the major BER polymerase, POLbeta. Moreover, extracts from a polq null mutant cell line show reduced BER activity, and POLQ, like POLbeta, accumulated rapidly at sites of base damage. Accordingly, POLQ and POLbeta share an overlapping function in the repair of oxidative base damage. Taken together, these results suggest a role for vertebrate POLQ in BER.

Publication types

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

MeSH terms

  • Animals
  • Avian Proteins / chemistry
  • Avian Proteins / genetics
  • Avian Proteins / physiology*
  • Cell Line
  • Chickens / genetics
  • Chickens / metabolism
  • Cisplatin / pharmacology
  • DNA Damage*
  • DNA Helicases / genetics
  • DNA Helicases / metabolism
  • DNA Helicases / physiology
  • DNA Polymerase beta / chemistry
  • DNA Polymerase beta / genetics
  • DNA Polymerase beta / physiology*
  • DNA Repair / physiology*
  • DNA-Directed DNA Polymerase / chemistry
  • DNA-Directed DNA Polymerase / genetics
  • DNA-Directed DNA Polymerase / physiology*
  • Gene Deletion
  • Hydrogen Peroxide / pharmacology
  • Mutation
  • Oxidative Stress*
  • Protein Structure, Tertiary
  • Ultraviolet Rays


  • Avian Proteins
  • Hydrogen Peroxide
  • DNA Polymerase beta
  • DNA-Directed DNA Polymerase
  • DNA Helicases
  • Cisplatin