Loss of the catalytic subunit of the DNA-dependent protein kinase in DNA double-strand-break-repair mutant mammalian cells.
The DNA-dependent protein kinase (DNA-PK) consists of three polypeptide components: Ku-70, Ku-80, and an approximately 350-kDa catalytic subunit (p350). The gene encoding the Ku-80 subunit is identical to the x-ray-sensitive group 5 complementing gene XRCC5. Expression of the Ku-80 cDNA rescues both DNA double-strand break (DSB) repair and V(D)J recombination in group 5 mutant cells. The involvement of Ku-80 in these processes suggests that the underlying defect in these mutant cells may be disruption of the DNA-PK holoenzyme. In this report we show that the p350 kinase subunit is deleted in cells derived from the severe combined immunodeficiency mouse and in the Chinese hamster ovary cell line V-3, both of which are defective in DSB repair and V(D)J recombination. A centromeric fragment of human chromosome 8 that complements the scid defect also restores p350 protein expression and rescues in vitro DNA-PK activity. These data suggest the scid gene may encode the p350 protein or regulate its expression and are consistent with a model whereby DNA-PK is a critical component of the DSB-repair pathway.
Peterson
S R
SR
Life Sciences Division, Los Alamos National Laboratory, NM 87545, USA.
Kurimasa
A
A
Oshimura
M
M
Dynan
W S
WS
Bradbury
E M
EM
Chen
D J
DJ
D000818:Animals; D034961:Antigens, Nuclear; D016466:CHO Cells; D006224:Cricetinae; D004265:DNA Helicases; D004260:DNA Repair / Q000235:genetics*; D051747:DNA-Activated Protein Kinase; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000302:isolation & purification; D005455:Fluorescent Antibody Technique; D000072200:Ku Autoantigen; D051379:Mice; D016513:Mice, SCID; D009687:Nuclear Proteins / Q000235:genetics* / Q000302:isolation & purification; D017346:Protein Serine-Threonine Kinases / Q000172:deficiency / Q000235:genetics* / Q000302:isolation & purification; D011995:Recombination, Genetic / Q000235:genetics*; D016511:Severe Combined Immunodeficiency / Q000235:genetics*
D034961:Antigens, Nuclear; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D051747:DNA-Activated Protein Kinase; D017346:Protein Serine-Threonine Kinases; D004265:DNA Helicases; C106893:XRCC5 protein, human; C000606512:Xrcc5 protein, mouse; C000606509:Xrcc6 protein, human; C000606510:Xrcc6 protein, mouse; D000072200:Ku Autoantigen