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.
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.
Errami
A
A
Department of Radiation Genetics and Chemical Mutagenesis, MGC, Leiden University-Medical Center, Leiden, The Netherlands.
He
D M
DM
Friedl
A A
AA
Overkamp
W J
WJ
Morolli
B
B
Hendrickson
E A
EA
Eckardt-Schupp
F
F
Oshimura
M
M
Lohman
P H
PH
Jackson
S P
SP
Zdzienicka
M Z
MZ
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
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