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Faure, V,Wenner, T,Cooley, C,Bourke, E,Farr, CJ,Takeda, S,Morrison, CG
2008
May
Dna Repair
Ku70 prevents genome instability resulting from heterozygosity of the telomerase RNA component in a vertebrate tumour line
Published
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Optional Fields
telomere telomerase DNA double-strand break repair homologous recombination nonhomologous end-joining gene targeting STRAND BREAK REPAIR CRITICALLY SHORT TELOMERES DNA-DAMAGE RESPONSE MOUSE CELLS LACKING HOMOLOGOUS RECOMBINATION REVERSE-TRANSCRIPTASE DYSFUNCTIONAL TELOMERES MAMMALIAN-CELLS IN-VITRO LENGTH
7
713
724
Telomere repeat sequences are added to linear chromosome ends by telomerase, an enzyme comprising a reverse transcriptase (TERT) and an RNA template component (TR). We aimed to investigate TR in the DT40 B-cell tumour line using gene targeting, but were unable to generate TR nulls, suggesting a requirement for TR in DT40 proliferation. Disruption of one TR allele reduced telomerase activity and caused a progressive decline in telomere and G-strand overhang length. We then examined the interactions between TR and cellular DNA double-strand break (DSB) repair. Deletion in TR+/- cells of the gene encoding the non-homologous end-joining protein, Ku70, caused rapid loss of G-strand overhangs. KU70(-/-)TR(+/-) cells proliferated more slowly than either single mutant and showed frequent mitotic aberrations. Activation of the DNA damage response was observed in TR-deficient cells and was exacerbated by Ku deficiency although frequent telomeric DNA damage signals were not observed until late passages. This activation of the DNA damage response was suppressed by deletion of Rad54, a key homologous recombination gene. These findings suggest that Ku. and telomerase cooperate to block homologous recombination from acting on telomeres. (c) 2008 Elsevier B.V. All rights reserved.
DOI 10.1016/j.dnarep.2008.01.008
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