title: DNA double-strand break repair pathway choice in Dictyostelium.
abstract: DNA double-strand breaks (DSBs) can be repaired by homologous recombination (HR) or non-homologous end joining (NHEJ). The mechanisms that govern whether a DSB is repaired by NHEJ or HR remain unclear. Here, we characterise DSB repair in the amoeba Dictyostelium. HR is the principal pathway responsible for resistance to DSBs during vegetative cell growth, a stage of the life cycle when cells are predominantly in G2. However, we illustrate that restriction-enzyme-mediated integration of DNA into the Dictyostelium genome is possible during this stage of the life cycle and that this is mediated by an active NHEJ pathway. We illustrate that Dclre1, a protein with similarity to the vertebrate NHEJ factor Artemis, is required for NHEJ independently of DNA termini complexity. Although vegetative dclre1(-) cells are not radiosensitive, they exhibit delayed DSB repair, further supporting a role for NHEJ during this stage of the life cycle. By contrast, cells lacking the Ku80 component of the Ku heterodimer that binds DNA ends to facilitate NHEJ exhibit no such defect and deletion of ku80 suppresses the DSB repair defect of dclre1(-) cells through increasing HR efficiency. These data illustrate a functional NHEJ pathway in vegetative Dictyostelium and the importance of Ku in regulating DSB repair choice during this phase of the life cycle.
authors.affiliation: Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK.
authors.forename: Duen-Wei
authors.initials: DW
authors.lastname: Hsu
authors.forename: Rhian
authors.initials: R
authors.lastname: Kiely
authors.forename: C Anne-Marie
authors.initials: CA
authors.lastname: Couto
authors.forename: Hong-Yu
authors.initials: HY
authors.lastname: Wang
authors.forename: Jessica J R
authors.initials: JJ
authors.lastname: Hudson
authors.forename: Christine
authors.initials: C
authors.lastname: Borer
authors.forename: Catherine J
authors.initials: CJ
authors.lastname: Pears
authors.forename: Nicholas D
authors.initials: ND
authors.lastname: Lakin
mesh_terms: D034961:Antigens, Nuclear / Q000235:genetics / Q000378:metabolism; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair; D016054:DNA, Protozoan / Q000235:genetics / Q000378:metabolism; D051747:DNA-Activated Protein Kinase / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D004023:Dictyostelium / Q000235:genetics* / Q000378:metabolism; D000072200:Ku Autoantigen; D011995:Recombination, Genetic; D014157:Transcription Factors / Q000172:deficiency / Q000235:genetics / Q000378:metabolism
chemical_list: D034961:Antigens, Nuclear; D016054:DNA, Protozoan; D004268:DNA-Binding Proteins; D014157:Transcription Factors; D051747:DNA-Activated Protein Kinase; D000072200:Ku Autoantigen