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. 2015 Jan 12;34(3):410–424. doi: 10.15252/embj.201488947

Figure 3.

Figure 3

BRCA1 and CtIP mediate Ku- and LIG4-independent telomere fusions
  1. Immortalized Brca1F/− MEFs were infected with retroviruses expressing the indicated shRNAs and/or Cre recombinase, followed by selection with puromycin for 72 h. Mitotic chromosomes isolated 48 h later were fixed and stained with a Cy3-conjugated (CCCTAA)3-PNA probe. The frequency of end-to-end chromosome-type fusions is represented as a percentage of fusions observed after TRF2 depletion. A minimum of 2,000 chromosomes were scored for each sample. Error bars represent SD of three independent experiments. P-values were calculated using an unpaired two-tailed t-test. NS, P > 0.05.
  2. Immortalized Brca1F/C61G MEFs were infected with retroviruses expressing the indicated shRNAs and/or Cre recombinase, followed by selection with puromycin for 72 h. The frequency of end-to-end chromosome-type fusions was analysed as in (A).
  3. MEFs of the indicated genotypes were infected with retroviruses expressing TRF2 and/or CtIP shRNAs, followed by selection with puromycin for 72 h. Cell extracts were prepared 48 h later and analysed by Western blotting as indicated. GAPDH was used as a loading control. *non-specific band. Cells treated as in (C) and (E) were arrested in mitosis with colcemid, and mitotic chromosomes isolated 48 h later were fixed and stained with a Cy3-conjugated (CCCTAA)3-PNA probe (D, F). The frequency of end-to-end chromosome-type fusions is represented as a percentage of fusions observed after TRF2 depletion. Error bars represent SD of two independent experiments. P-values were calculated using an unpaired two-tailed t-test. *P ≤ 0.05.