title: The Drosophila melanogaster DNA Ligase IV gene plays a crucial role in the repair of radiation-induced DNA double-strand breaks and acts synergistically with Rad54.
abstract: DNA Ligase IV has a crucial role in double-strand break (DSB) repair through nonhomologous end joining (NHEJ). Most notably, its inactivation leads to embryonic lethality in mammals. To elucidate the role of DNA Ligase IV (Lig4) in DSB repair in a multicellular lower eukaryote, we generated viable Lig4-deficient Drosophila strains by P-element-mediated mutagenesis. Embryos and larvae of mutant lines are hypersensitive to ionizing radiation but hardly so to methyl methanesulfonate (MMS) or the crosslinking agent cis-diamminedichloroplatinum (cisDDP). To determine the relative contribution of NHEJ and homologous recombination (HR) in Drosophila, Lig4; Rad54 double-mutant flies were generated. Survival studies demonstrated that both HR and NHEJ have a major role in DSB repair. The synergistic increase in sensitivity seen in the double mutant, in comparison with both single mutants, indicates that both pathways partially overlap. However, during the very first hours after fertilization NHEJ has a minor role in DSB repair after exposure to ionizing radiation. Throughout the first stages of embryogenesis of the fly, HR is the predominant pathway in DSB repair. At late stages of development NHEJ also becomes less important. The residual survival of double mutants after irradiation strongly suggests the existence of a third pathway for the repair of DSBs in Drosophila.
authors.affiliation: Department of Toxicogenetics, Leiden University Medical Center, 2333 AL, Leiden, The Netherlands.
authors.forename: Marcin M
authors.initials: MM
authors.lastname: Gorski
authors.forename: Jan C J
authors.initials: JC
authors.lastname: Eeken
authors.forename: Anja W M
authors.initials: AW
authors.lastname: de Jong
authors.forename: Ilse
authors.initials: I
authors.lastname: Klink
authors.forename: Marjan
authors.initials: M
authors.lastname: Loos
authors.forename: Ron J
authors.initials: RJ
authors.lastname: Romeijn
authors.forename: Bert L
authors.initials: BL
authors.lastname: van Veen
authors.forename: Leon H
authors.initials: LH
authors.lastname: Mullenders
authors.forename: Wouter
authors.initials: W
authors.lastname: Ferro
authors.forename: Albert
authors.initials: A
authors.lastname: Pastink
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D002945:Cisplatin / Q000633:toxicity; D003432:Cross-Linking Reagents / Q000633:toxicity; D004247:DNA / Q000528:radiation effects*; D004249:DNA Damage; D004265:DNA Helicases; D000072481:DNA Ligase ATP; D011088:DNA Ligases / Q000502:physiology*; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000502:physiology*; D029721:Drosophila Proteins / Q000502:physiology*; D004331:Drosophila melanogaster / Q000187:drug effects / Q000201:enzymology / Q000235:genetics* / Q000528:radiation effects; D004527:Egg Proteins / Q000502:physiology*; D005260:Female; D006720:Homozygote; D008297:Male; D008741:Methyl Methanesulfonate / Q000633:toxicity; D008969:Molecular Sequence Data; D009153:Mutagens / Q000633:toxicity; D017386:Sequence Homology, Amino Acid; D015996:Survival Rate
chemical_list: D003432:Cross-Linking Reagents; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D004527:Egg Proteins; D009153:Mutagens; D004247:DNA; D008741:Methyl Methanesulfonate; C108443:okr protein, Drosophila; D004265:DNA Helicases; D011088:DNA Ligases; D000072481:DNA Ligase ATP; D002945:Cisplatin