title: Role of DNA polymerase eta in the UV mutation spectrum in human cells.
abstract: 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.
authors.affiliation: Laboratory of Genetic Instability and Cancer, UPR 2169 CNRS, Institut Gustave Roussy, 94805 Villejuif, France. stary@igr.fr
authors.forename: Anne
authors.initials: A
authors.lastname: Stary
authors.forename: Patricia
authors.initials: P
authors.lastname: Kannouche
authors.forename: Alan R
authors.initials: AR
authors.lastname: Lehmann
authors.forename: Alain
authors.initials: A
authors.lastname: Sarasin
mesh_terms: D001483:Base Sequence; D002110:Caffeine / Q000494:pharmacology; D002453:Cell Cycle; D002460:Cell Line; D002461:Cell Line, Transformed; D002470:Cell Survival; D004249:DNA Damage; D004259:DNA-Directed DNA Polymerase / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D017353:Gene Deletion; D005822:Genetic Vectors; D006801:Humans; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009154:Mutation; D010957:Plasmids; D011740:Pyrimidine Dimers; D017422:Sequence Analysis, DNA; D013539:Simian virus 40; D014162:Transfection; D014466:Ultraviolet Rays / Q000009:adverse effects*; D014983:Xeroderma Pigmentosum / Q000235:genetics; D001616:beta-Galactosidase / Q000235:genetics; D000099270:Y-Family DNA Polymerases
chemical_list: D002110:Caffeine; D004259:DNA-Directed DNA Polymerase; D011740:Pyrimidine Dimers; D001616:beta-Galactosidase; C112338:Rad30 protein; D000099270:Y-Family DNA Polymerases