title: RAD51 supports spontaneous non-homologous recombination in mammalian cells, but not the corresponding process induced by topoisomerase inhibitors.
abstract: The RAD51 protein has been shown to participate in homologous recombination by promoting ATP-dependent homologous pairing and strand transfer reactions. In the present study, we have investigated the possible involvement of RAD51 in non-homologous recombination. We demonstrate that overexpression of CgRAD51 enhances the frequency of spontaneous non-homologous recombination in the hprt gene of Chinese hamster cells. However, the rate of non-homologous recombination induced by the topoisomerase inhibitors campothecin and etoposide was not altered by overexpression of RAD51. These results indicate that the RAD51 protein may perform a function in connection with spontaneous non-homologous recombination that is not essential to or not rate-limiting for non-homologous recombination induced by camptothecin or etoposide. We discuss the possibility that the role played by RAD51 in non-homologous recombination observed here may not be linked to non-homologous end-joining.
authors.affiliation: Department of Genetic and Cellular Toxicology, Wallenberg Laboratory, Stockholm University, Lilla Frescativ. 7, S-106 91 Stockholm, Sweden.
authors.forename: C
authors.initials: C
authors.lastname: Arnaudeau
authors.forename: L
authors.initials: L
authors.lastname: Rozier
authors.forename: C
authors.initials: C
authors.lastname: Cazaux
authors.forename: M
authors.initials: M
authors.lastname: Defais
authors.forename: D
authors.initials: D
authors.lastname: Jenssen
authors.forename: T
authors.initials: T
authors.lastname: Helleday
mesh_terms: D000818:Animals; D002166:Camptothecin / Q000494:pharmacology; D002460:Cell Line; D006224:Cricetinae; D003412:Cricetulus; D004264:DNA Topoisomerases, Type I / Q000378:metabolism; D004274:DNA, Recombinant; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005047:Etoposide / Q000494:pharmacology; D015870:Gene Expression; D007041:Hypoxanthine Phosphoribosyltransferase / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D010957:Plasmids / Q000235:genetics; D017354:Point Mutation; D051135:Rad51 Recombinase; D011995:Recombination, Genetic / Q000187:drug effects* / Q000235:genetics; D059004:Topoisomerase I Inhibitors; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000235:genetics
chemical_list: D004274:DNA, Recombinant; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D059004:Topoisomerase I Inhibitors; D016159:Tumor Suppressor Protein p53; D005047:Etoposide; D007041:Hypoxanthine Phosphoribosyltransferase; D051135:Rad51 Recombinase; D004264:DNA Topoisomerases, Type I; D002166:Camptothecin