Ku86 represses lethal telomere deletion events in human somatic cells.
Nonhomologous end joining (NHEJ), a form of DNA double-strand break (DSB) repair, is conserved from bacteria to humans. One essential NHEJ factor is Ku, which consists of a heterodimer of Ku70 and Ku86. In a plethora of model systems, null mutations for Ku70 or Ku86 present with defects in DNA DSB repair, variable(diversity)joining [V(D)J] recombination, and/or telomere maintenance. The complete loss of Ku from bacteria to mice is, however, compatible with viability. In striking contrast, human patients with mutations of either Ku subunit have never been described. Here, we have used recombinant adeno-associated virus-mediated gene targeting to produce a human somatic cell line that expresses a conditionally null allele of Ku86. The induced loss of Ku86 results in cell death accompanied by massive telomere loss in the form of t-circles. Thus, Ku86 is an essential gene in human somatic cells because of its requirement, not in NHEJ or V(D)J recombination, but in telomere maintenance.
Wang
Yongbao
Y
Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, MN 55455, USA.
Ghosh
Goutam
G
Hendrickson
Eric A
EA
D034961:Antigens, Nuclear / Q000235:genetics* / Q000378:metabolism; D015153:Blotting, Western; D002470:Cell Survival; D002872:Chromosome Deletion; D053903:DNA Breaks, Double-Stranded; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D000229:Dependovirus / Q000235:genetics; D004586:Electrophoresis / Q000379:methods; D005455:Fluorescent Antibody Technique; D018390:Gene Targeting / Q000379:methods; D045325:HCT116 Cells; D006657:Histones / Q000378:metabolism; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D000072200:Ku Autoantigen; D009154:Mutation; D016615:Telomere / Q000235:genetics* / Q000378:metabolism; D014162:Transfection
D034961:Antigens, Nuclear; D004268:DNA-Binding Proteins; C468783:H2AX protein, human; D006657:Histones; C000606512:Xrcc5 protein, mouse; C000606509:Xrcc6 protein, human; C000606510:Xrcc6 protein, mouse; D000072200:Ku Autoantigen