Involvement of DNA polymerase beta in protection against the cytotoxicity of oxidative DNA damage

DNA Repair (Amst). 2002 Apr 29;1(4):317-33. doi: 10.1016/s1568-7864(02)00008-3.


We had shown previously that DNA polymerase beta (beta-pol) null mouse fibroblasts, deficient in base excision repair (BER), are hypersensitive to monofunctional methylating agents but not to hydrogen peroxide (H2O2). This is surprising because beta-pol is thought to be involved in BER of oxidative as well as methylated DNA damage. We confirm these findings here in early-passage cells. However, with time in culture, beta-pol null cells become hypersensitive to H2O2 and other reactive oxygen species-generating agents. Analysis of in vitro BER reveals a strong deficiency in single-nucleotide BER of 8-oxoguanine (8-oxoG) by both early- and late-passage beta-pol null cell extracts. Therefore, in early-passage wild-type and beta-pol null cells, the capacity for single-nucleotide BER of 8-oxoG does not correlate with cellular sensitivity to H2O2. Expression of beta-pol protein in the late-passage null cells almost completely reverses the H2O2-hypersensitivity phenotype. Methoxyamine (MX) treatment sensitizes late-passage wild-type cells to H2O2 as expected for beta-pol-mediated single-nucleotide BER; however in beta-pol null cells, MX has no effect. The data indicate a role(s) of beta-pol-dependent repair in protection against the cytotoxicity of oxidative DNA damage in wild-type cells.

MeSH terms

  • Animals
  • Antineoplastic Agents / toxicity
  • Blotting, Western
  • Cell Division / drug effects
  • Cell Survival / drug effects
  • Cytoprotection / physiology
  • DNA Damage / drug effects*
  • DNA Polymerase beta / genetics
  • DNA Polymerase beta / physiology*
  • DNA Primers / chemistry
  • DNA Repair*
  • DNA-Formamidopyrimidine Glycosylase
  • Fibroblasts / drug effects
  • Fibroblasts / enzymology*
  • Glutathione / deficiency
  • Glutathione / metabolism
  • Guanosine / analogs & derivatives*
  • Guanosine / metabolism
  • Hydrogen Peroxide / toxicity
  • Hydroxylamines / toxicity
  • In Vitro Techniques
  • Mice
  • N-Glycosyl Hydrolases / metabolism
  • Oxidants / toxicity*
  • Peroxynitrous Acid / toxicity
  • Poly(ADP-ribose) Polymerase Inhibitors
  • Poly(ADP-ribose) Polymerases / drug effects
  • Transfection


  • Antineoplastic Agents
  • DNA Primers
  • Hydroxylamines
  • Oxidants
  • Poly(ADP-ribose) Polymerase Inhibitors
  • Guanosine
  • Peroxynitrous Acid
  • 8-hydroxyguanosine
  • methoxyamine
  • Hydrogen Peroxide
  • Poly(ADP-ribose) Polymerases
  • DNA Polymerase beta
  • N-Glycosyl Hydrolases
  • DNA-Formamidopyrimidine Glycosylase
  • Glutathione