A targeted DNA-PKcs-null mutation reveals DNA-PK-independent functions for KU in V(D)J recombination.
The DNA-dependent protein kinase (DNA-PK) consists of Ku70, Ku80, and a large catalytic subunit, DNA-PKcs. Targeted inactivation of the Ku70 or Ku80 genes results in elevated ionizing radiation (IR) sensitivity and inability to perform both V(D)J coding-end and signal (RS)-end joining in cells, with severe growth retardation plus immunodeficiency in mice. In contrast, we now demonstrate that DNA-PKcs-null mice generated by gene-targeted mutation, while also severely immunodeficient, exhibit no growth retardation. Furthermore, DNA-PKcs-null cells are blocked for V(D)J coding-end joining, but retain normal RS-end joining. Finally, while DNA-PK-null fibroblasts exhibited increased IR sensitivity, DNA-PKcs-deficient ES cells did not. We conclude that Ku70 and Ku80 may have functions in V(D)J recombination and DNA repair that are independent of DNA-PKcs.
Howard Hughes Medical Institute, The Children's Hospital, The Center for Blood Research and Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA.
Y
Y
Gao
J
J
Chaudhuri
C
C
Zhu
L
L
Davidson
D T
DT
Weaver
F W
FW
Alt
D000818:Animals; D034961:Antigens, Nuclear; D004265:DNA Helicases; D051747:DNA-Activated Protein Kinase; D004268:DNA-Binding Proteins / Q000502:physiology*; D004622:Embryo, Mammalian; D005260:Female; D005347:Fibroblasts / Q000201:enzymology / Q000528:radiation effects; D015326:Gene Rearrangement, B-Lymphocyte, Heavy Chain / Q000235:genetics*; D018390:Gene Targeting; D007133:Immunoglobulin Joining Region / Q000235:genetics; D000072200:Ku Autoantigen; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009154:Mutation / Q000235:genetics; D009687:Nuclear Proteins / Q000502:physiology*; D010641:Phenotype; D017346:Protein Serine-Threonine Kinases / Q000096:biosynthesis / Q000235:genetics* / Q000502:physiology; D011839:Radiation, Ionizing; D016511:Severe Combined Immunodeficiency / Q000235:genetics; D015398:Signal Transduction; D013234:Stem Cells / Q000201:enzymology / Q000378:metabolism / Q000502:physiology / Q000528:radiation effects; D013950:Thymus Gland / Q000166:cytology / Q000502:physiology
D034961:Antigens, Nuclear; D004268:DNA-Binding Proteins; D007133:Immunoglobulin Joining Region; D009687:Nuclear Proteins; D051747:DNA-Activated Protein Kinase; D017346:Protein Serine-Threonine Kinases; D004265:DNA Helicases; C106893:XRCC5 protein, human; C000606509:Xrcc6 protein, human; C000606510:Xrcc6 protein, mouse; D000072200:Ku Autoantigen