Evidence for the involvement of human DNA polymerase N in the repair of DNA interstrand cross-links

Biochemistry. 2009 Dec 15;48(49):11817-24. doi: 10.1021/bi9015346.


Human DNA polymerase N (PolN) is an A-family nuclear DNA polymerase whose function is unknown. This study examines the possible role of PolN in DNA repair in human cells treated with PolN-targeted siRNA. HeLa cells with siRNA-mediated knockdown of PolN were more sensitive than control cells to DNA cross-linking agent mitomycin C (MMC) but were not hypersensitive to UV irradiation. The MMC hypersensitivity of PolN knockdown cells was rescued by the overexpression of DNA polymerase-proficient PolN but not by DNA polymerase-deficient PolN. Furthermore, in vitro experiments showed that purified PolN conducts low-efficiency nonmutagenic bypass of a psoralen DNA interstrand cross-link (ICL), whose structure resembles an intermediate in the proposed pathway of ICL repair. These results suggest that PolN might play a role in translesion DNA synthesis during ICL repair in human cells.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Base Sequence
  • Cell Nucleus / drug effects
  • Cell Nucleus / enzymology
  • Cell Nucleus / genetics
  • Cross-Linking Reagents / pharmacology
  • DNA Damage* / genetics
  • DNA Helicases / chemistry
  • DNA Helicases / physiology
  • DNA Repair Enzymes / chemistry
  • DNA Repair Enzymes / physiology*
  • DNA Repair* / drug effects
  • DNA Repair* / genetics
  • DNA-Binding Proteins / genetics
  • DNA-Directed DNA Polymerase / biosynthesis
  • DNA-Directed DNA Polymerase / chemistry
  • DNA-Directed DNA Polymerase / deficiency
  • DNA-Directed DNA Polymerase / genetics
  • DNA-Directed DNA Polymerase / physiology*
  • HeLa Cells
  • Humans
  • Mitomycin / pharmacology
  • Molecular Sequence Data
  • Nuclear Proteins / biosynthesis
  • Nuclear Proteins / deficiency
  • Nuclear Proteins / genetics
  • Nuclear Proteins / physiology
  • RNA, Small Interfering / pharmacology


  • Cross-Linking Reagents
  • DNA-Binding Proteins
  • Nuclear Proteins
  • RNA, Small Interfering
  • xeroderma pigmentosum group F protein
  • Mitomycin
  • DNA polymerase N, human
  • DNA-Directed DNA Polymerase
  • DNA Helicases
  • DNA Repair Enzymes