title: scid cells are deficient in Ku and replication protein A phosphorylation by the DNA-dependent protein kinase.
abstract: Cell mutants of the Ku nuclear DNA-binding complex are ionizing radiation sensitive and show V(D)J recombination defects. Ku binds and activates a catalytic subunit of DNA-dependent protein kinase (DNA-PK), although the substrates for DNA-PK are unknown. We found that scid cell extracts were deficient in Ku phosphorylation by DNA-PK. Human chromosome 8-complemented scid cells, containing the human DNA-PK catalytic subunit, restored Ku phosphorylation. Likewise, radiation-induced RPA hyperphosphorylation was not completed in scid cells compared with control or chromosome 8-reconstituted cells. Thus, the inactivity of DNA-PK is likely responsible for the repair and recombination defects in scid cells.
authors.affiliation: Division of Tumor Immunology, Dana-Farber Cancer Institute, Boston, Massachusetts 02115, USA.
authors.forename: N V
authors.initials: NV
authors.lastname: Boubnov
authors.forename: D T
authors.initials: DT
authors.lastname: Weaver
mesh_terms: D000818:Animals; D034961:Antigens, Nuclear; D001402:B-Lymphocytes; D002457:Cell Extracts; D002460:Cell Line; D002461:Cell Line, Transformed; D002898:Chromosomes, Human, Pair 8; D004247:DNA / Q000378:metabolism; D004265:DNA Helicases; D004260:DNA Repair; D051747:DNA-Activated Protein Kinase; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005347:Fibroblasts; D005720:Gamma Rays; D005816:Genetic Complementation Test; D006801:Humans; D000072200:Ku Autoantigen; D051379:Mice; D016513:Mice, SCID; D009687:Nuclear Proteins / Q000378:metabolism*; D010766:Phosphorylation / Q000528:radiation effects; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011995:Recombination, Genetic; D051716:Replication Protein A; D016511:Severe Combined Immunodeficiency / Q000378:metabolism*
chemical_list: D034961:Antigens, Nuclear; D002457:Cell Extracts; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; C497167:RPA1 protein, human; D051716:Replication Protein A; C497168:Rpa1 protein, mouse; D004247:DNA; D051747:DNA-Activated Protein Kinase; C497263:PRKDC protein, human; D017346:Protein Serine-Threonine Kinases; D004265:DNA Helicases; C106893:XRCC5 protein, human; C000606509:Xrcc6 protein, human; C000606510:Xrcc6 protein, mouse; D000072200:Ku Autoantigen