Role of DNA polymerase eta in the UV mutation spectrum in human cells

J Biol Chem. 2003 May 23;278(21):18767-75. doi: 10.1074/jbc.M211838200. Epub 2003 Mar 18.


In humans, inactivation of the DNA polymerase eta gene (pol eta) results in sunlight sensitivity and causes the cancer-prone xeroderma pigmentosum variant syndrome (XP-V). Cells from XP-V individuals have a reduced capacity to replicate UV-damaged DNA and show hypermutability after UV exposure. Biochemical assays have demonstrated the ability of pol eta to bypass cis-syn-cyclobutane thymine dimers, the most common lesion generated in DNA by UV. In most cases, this bypass is error-free. To determine the actual requirement of pol eta in vivo, XP-V cells (XP30RO) were complemented by the wild type pol eta gene. We have used two pol eta-corrected clones to study the in vivo characteristics of mutations produced by DNA polymerases during DNA synthesis of UV-irradiated shuttle vectors transfected into human host cells, which had or had not been exposed previously to UV radiation. The functional complementation of XP-V cells by pol eta reduced the mutation frequencies both at CG and TA base pairs and restored UV mutagenesis to a normal level. UV irradiation of host cells prior to transfection strongly increased the mutation frequency in undamaged vectors and, in addition, especially in the pol eta-deficient XP30RO cells at 5'-TT sites in UV-irradiated plasmids. These results clearly show the protective role of pol eta against UV-induced lesions and the activation by UV of pol eta-independent mutagenic processes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Sequence
  • Caffeine / pharmacology
  • Cell Cycle
  • Cell Line
  • Cell Line, Transformed
  • Cell Survival
  • DNA Damage*
  • DNA-Directed DNA Polymerase / chemistry
  • DNA-Directed DNA Polymerase / genetics
  • DNA-Directed DNA Polymerase / physiology*
  • Gene Deletion
  • Genetic Vectors
  • Humans
  • Molecular Sequence Data
  • Mutagenesis
  • Mutation*
  • Plasmids
  • Pyrimidine Dimers
  • Sequence Analysis, DNA
  • Simian virus 40
  • Transfection
  • Ultraviolet Rays / adverse effects*
  • Xeroderma Pigmentosum / genetics
  • beta-Galactosidase / genetics


  • Pyrimidine Dimers
  • Caffeine
  • DNA-Directed DNA Polymerase
  • Rad30 protein
  • beta-Galactosidase