Role for DNA polymerase beta in response to ionizing radiation

DNA Repair (Amst). 2007 Feb 4;6(2):202-12. doi: 10.1016/j.dnarep.2006.09.011. Epub 2006 Nov 28.


Evidence for a role of DNA polymerase beta in determining radiosensitivity is conflicting. In vitro assays show an involvement of DNA polymerase beta in single strand break repair and base excision repair of oxidative damages, both products of ionizing radiation. Nevertheless the lack of DNA polymerase beta has been shown to have no effect on radiosensitivity. Here we show that mouse embryonic fibroblasts deficient in DNA polymerase beta are considerably more sensitive to ionizing radiation than wild-type cells, but only when confluent. The inhibitor methoxyamine renders abasic sites refractory to the dRP lyase activity of DNA polymerase beta. Methoxyamine did not significantly change radiosensitivity of wild-type fibroblasts in log phase. However, DNA polymerase beta deficient cells in log phase were radiosensitized by methoxyamine. Alkaline comet assays confirmed repair inhibition of ionizing radiation induced damage by methoxyamine in these cells, indicating both the existence of a polymerase beta-dependent long patch pathway and the involvement of another methoxyamine sensitive process, implying the participation of a second short patch polymerase(s) other than DNA polymerase beta. This is the first evidence of a role for DNA polymerase beta in radiosensitivity in vivo.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Cycle
  • Cell Line
  • Cell Survival / radiation effects
  • Colony-Forming Units Assay
  • DNA Damage
  • DNA Polymerase beta / deficiency
  • DNA Polymerase beta / genetics
  • DNA Polymerase beta / metabolism*
  • DNA Repair / drug effects
  • DNA Repair / physiology*
  • Hydroxylamines / pharmacology
  • Mice
  • Mice, Knockout
  • Radiation Tolerance / drug effects
  • Radiation Tolerance / physiology*


  • Hydroxylamines
  • methoxyamine
  • DNA Polymerase beta