FIG 6.

Growth arrest and telomere fusions in cells expressing TIN2-L247E. (A) Growth curve of SV40-LT-immortalized TIN2^−/− MEFs expressing an empty vector (EV) or the indicated FLAG-HA₂ TIN2 alleles. (B) Examples of telomere fusions in metaphases of TIN2-deficient cells expressing the indicated TIN2 alleles or no TIN2 (EV) (72 h post-Cre). Green, TelC PNA probe; red, DAPI DNA stain. (C) Summary of telomere phenotypes in TIN2-deficient cells expressing TIN2 alleles, as determined by FISH, as shown in panel B. Values are averages and SDs from 3 independent experiments. Chromosome-type and chromatid-type telomere fusions were scored on 3,000 to 5,000 telomeres/experiment. Long-arm sister telomere fusions and fragile telomeres were scored on 2,000 to 3,000 telomeres/experiment. (D) Quantification of chromosome-type fusions in TIN2-deleted cells expressing an EV or TIN2-L247E with or without exogenously expressed TRF2. Averages and SDs are from three independent experiments (2,000 to 3,000 telomeres/experiment). **, P < 0.05 (paired Student t test).