title: XR-C1, a new CHO cell mutant which is defective in DNA-PKcs, is impaired in both V(D)J coding and signal joint formation.
abstract: DNA-dependent protein kinase (DNA-PK) plays an important role in DNA double-strand break (DSB) repair and V(D)J recombination. We have isolated a new X-ray-sensitive CHO cell line, XR-C1, which is impaired in DSB repair and which was assigned to complementation group 7, the group that is defective in the XRCC7 / SCID ( Prkdc ) gene encoding the catalytic subunit of DNA-PK (DNA-PKcs). Consistent with this complementation analysis, XR-C1 cells lackeddetectable DNA-PKcs protein, did not display DNA-PK catalytic activity and were complemented by the introduction of a single human chromosome 8 (providing the Prkdc gene). The impact of the XR-C1 mutation on V(D)J recombination was quite different from that found in most rodent cells defective in DNA-PKcs, which are preferentially blocked in coding joint formation, whereas XR-C1 cells were defective in forming both coding and signal joints. These results suggest that DNA-PKcs is required for both coding and signal joint formation during V(D)J recombination and that the XR-C1 mutant cell line may prove to be a useful tool in understanding this pathway.
authors.affiliation: Department of Radiation Genetics and Chemical Mutagenesis, MGC, Leiden University-Medical Center, Leiden, The Netherlands.
authors.forename: A
authors.initials: A
authors.lastname: Errami
authors.forename: D M
authors.initials: DM
authors.lastname: He
authors.forename: A A
authors.initials: AA
authors.lastname: Friedl
authors.forename: W J
authors.initials: WJ
authors.lastname: Overkamp
authors.forename: B
authors.initials: B
authors.lastname: Morolli
authors.forename: E A
authors.initials: EA
authors.lastname: Hendrickson
authors.forename: F
authors.initials: F
authors.lastname: Eckardt-Schupp
authors.forename: M
authors.initials: M
authors.lastname: Oshimura
authors.forename: P H
authors.initials: PH
authors.lastname: Lohman
authors.forename: S P
authors.initials: SP
authors.lastname: Jackson
authors.forename: M Z
authors.initials: MZ
authors.lastname: Zdzienicka
mesh_terms: D000818:Animals; D016466:CHO Cells; D002898:Chromosomes, Human, Pair 8; D006224:Cricetinae; D004249:DNA Damage; D051747:DNA-Activated Protein Kinase; D004268:DNA-Binding Proteins; D005816:Genetic Complementation Test; D006801:Humans; D006822:Hybrid Cells; D007133:Immunoglobulin Joining Region / Q000235:genetics*; D007135:Immunoglobulin Variable Region / Q000235:genetics*; D009153:Mutagens / Q000494:pharmacology; D009154:Mutation; D009687:Nuclear Proteins; D017346:Protein Serine-Threonine Kinases / Q000235:genetics*; D011995:Recombination, Genetic / Q000235:genetics*; D014965:X-Rays
chemical_list: D004268:DNA-Binding Proteins; D007133:Immunoglobulin Joining Region; D007135:Immunoglobulin Variable Region; D009153:Mutagens; D009687:Nuclear Proteins; D051747:DNA-Activated Protein Kinase; C497263:PRKDC protein, human; D017346:Protein Serine-Threonine Kinases