title: DNA-PKcs-dependent signaling of DNA damage in Dictyostelium discoideum.
abstract: DNA double-strand breaks (DSBs) can be repaired by either homologous recombination (HR) or nonhomologous end-joining (NHEJ). In vertebrates, the first step in NHEJ is recruitment of the DNA-dependent protein kinase (DNA-PK) to DNA termini. DNA-PK consists of a catalytic subunit (DNA-PKcs) that is recruited to DNA ends by the Ku70/Ku80 heterodimer. Although Ku has been identified in a wide variety of organisms, to date DNA-PKcs has only been identified experimentally in vertebrates. Here, we report the identification of DNA-PK in the nonvertebrate Dictyostelium. Dictyostelium Ku80 contains a conserved domain previously implicated in recruiting DNA-PKcs to DNA and consistent with this observation, we have identified DNA-PKcs in the Dictyostelium genome. Disruption of the gene encoding Dictyostelium DNA-PKcs results in sensitivity to DNA DSBs and defective H2AX phosphorylation in response to this form of DNA damage. However, these phenotypes are only apparent when DNA damage is administered in G(1) phase of the cell cycle. These data illustrate a cell cycle-dependent requirement for Dictyostelium DNA-PK in signaling and combating DNA DSBs and represent the first experimental verification of DNA-PKcs in a nonvertebrate organism.
authors.affiliation: Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom.
authors.forename: Jessica J R
authors.initials: JJ
authors.lastname: Hudson
authors.forename: Duen-Wei
authors.initials: DW
authors.lastname: Hsu
authors.forename: Kunde
authors.initials: K
authors.lastname: Guo
authors.forename: Natasha
authors.initials: N
authors.lastname: Zhukovskaya
authors.forename: Po-Hsien
authors.initials: PH
authors.lastname: Liu
authors.forename: Jeffrey G
authors.initials: JG
authors.lastname: Williams
authors.forename: Catherine J
authors.initials: CJ
authors.lastname: Pears
authors.forename: Nicholas D
authors.initials: ND
authors.lastname: Lakin
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D034961:Antigens, Nuclear / Q000235:genetics / Q000378:metabolism; D001761:Bleomycin; D015153:Blotting, Western; D020134:Catalytic Domain / Q000235:genetics / Q000502:physiology*; D016000:Cluster Analysis; D019295:Computational Biology; D004249:DNA Damage; D051747:DNA-Activated Protein Kinase / Q000235:genetics / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004023:Dictyostelium / Q000235:genetics / Q000502:physiology*; D005434:Flow Cytometry; D006657:Histones / Q000378:metabolism; D000072200:Ku Autoantigen; D008969:Molecular Sequence Data; D010766:Phosphorylation; D010802:Phylogeny; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology*
chemical_list: D034961:Antigens, Nuclear; D004268:DNA-Binding Proteins; D006657:Histones; D001761:Bleomycin; D051747:DNA-Activated Protein Kinase; D000072200:Ku Autoantigen