Base excision repair is efficient in cells lacking poly(ADP-ribose) polymerase 1

Nucleic Acids Res. 2000 Oct 15;28(20):3887-96. doi: 10.1093/nar/28.20.3887.


Poly(ADP-ribose) polymerase 1 (PARP-1) is a nuclear enzyme that is activated by binding to DNA breaks induced by ionizing radiation or through repair of altered bases in DNA by base excision repair. Mice lacking PARP-1 and, in certain cases, the cells derived from these mice exhibit hypersensitivity to ionizing radiation and alkylating agents. In this study we investigated base excision repair in cells lacking PARP-1 in order to elucidate whether their augmented sensitivity to DNA damaging agents is due to an impairment of the base excision repair pathway. Extracts prepared from wild-type cells or cells lacking PARP-1 were similar in their ability to repair plasmid DNA damaged by either X-rays (single-strand DNA breaks) or by N:-methyl-N:'-nitro-N:-nitrosoguanidine (methylated bases). In addition, we demonstrated in vivo that PARP-1-deficient cells treated with N:-methyl-N:'-nitro-N:-nitrosoguanidine repaired their genomic DNA as efficiently as wild-type cells. Therefore, we conclude that cells lacking PARP-1 have a normal capacity to repair single-strand DNA breaks inflicted by X-irradiation or breaks formed during the repair of modified bases. We propose that the hypersensitivity of PARP-1 null mutant cells to gamma-irradiation and alkylating agents is not directly due to a defect in DNA repair itself, but rather results from greatly reduced poly(ADP-ribose) formation during base excision repair in these cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Base Pair Mismatch / drug effects
  • Base Pair Mismatch / genetics*
  • Base Pair Mismatch / radiation effects
  • Cell Extracts
  • Cell Line
  • Cell-Free System
  • DNA Damage / drug effects
  • DNA Damage / genetics
  • DNA Damage / radiation effects
  • DNA Methylation / drug effects
  • DNA Repair / drug effects
  • DNA Repair / genetics*
  • DNA Repair / radiation effects
  • DNA, Single-Stranded / biosynthesis
  • DNA, Single-Stranded / drug effects
  • DNA, Single-Stranded / genetics
  • DNA, Single-Stranded / radiation effects
  • Dose-Response Relationship, Radiation
  • Fibroblasts
  • Gene Deletion*
  • Kinetics
  • Methylnitronitrosoguanidine / pharmacology
  • Mice
  • Models, Genetic
  • Mutagens / pharmacology
  • NAD / metabolism
  • Plasmids / drug effects
  • Plasmids / genetics
  • Plasmids / radiation effects
  • Poly(ADP-ribose) Polymerases / deficiency*
  • Poly(ADP-ribose) Polymerases / genetics
  • Poly(ADP-ribose) Polymerases / physiology
  • Radiation Tolerance
  • X-Rays


  • Cell Extracts
  • DNA, Single-Stranded
  • Mutagens
  • NAD
  • Methylnitronitrosoguanidine
  • Poly(ADP-ribose) Polymerases