title: Poly(ADP-ribose) polymerase (PARP-1) has a controlling role in homologous recombination.
abstract: Cells with non-functional poly(ADP-ribose) polymerase (PARP-1) show increased levels of sister chromatid exchange, suggesting a hyper recombination phenotype in these cells. To further investigate the involvement of PARP-1 in homologous recombination (HR) we investigated how PARP-1 affects nuclear HR sites (Rad51 foci) and HR repair of an endonuclease-induced DNA double-strand break (DSB). Several proteins involved in HR localise to Rad51 foci and HR-deficient cells fail to form Rad51 foci in response to DNA damage. Here, we show that PARP-1 mainly does not localise to Rad51 foci and that Rad51 foci form in PARP-1-/- cells, also in response to hydroxyurea. Furthermore, we show that homology directed repair following induction of a site-specific DSB is normal in PARP-1-inhibited cells. In contrast, inhibition or loss of PARP-1 increases spontaneous Rad51 foci formation, confirming a hyper recombination phenotype in these cells. Our data suggest that PARP-1 controls DNA damage recognised by HR and that it is not involved in executing HR as such.
authors.affiliation: Department of Genetic and Cellular Toxicology, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm, Sweden.
authors.forename: Niklas
authors.initials: N
authors.lastname: Schultz
authors.forename: Elena
authors.initials: E
authors.lastname: Lopez
authors.forename: Nasrollah
authors.initials: N
authors.lastname: Saleh-Gohari
authors.forename: Thomas
authors.initials: T
authors.lastname: Helleday
mesh_terms: D000818:Animals; D002460:Cell Line; D045744:Cell Line, Tumor; D004247:DNA / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D006918:Hydroxyurea / Q000494:pharmacology; D007546:Isoquinolines / Q000494:pharmacology; D009154:Mutation; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011065:Poly(ADP-ribose) Polymerases / Q000235:genetics / Q000378:metabolism*; D051135:Rad51 Recombinase; D011995:Recombination, Genetic
chemical_list: D004268:DNA-Binding Proteins; D007546:Isoquinolines; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; C095653:1,5-dihydroxyisoquinoline; D004247:DNA; D011065:Poly(ADP-ribose) Polymerases; C495153:RAD51 protein, human; D051135:Rad51 Recombinase; D006918:Hydroxyurea