Fig. 3: Impaired cell cycle progression due to telomere end fusions and telomere attrition in Tcea1^–/– MEFs.

A Immunostaining of α-TUBULIN (α-TUB) in Tcea1^–/– MEFs (n = 3). Graph depicts the percentage of cells with at least one abnormality (micronuclei – white arrows, chromatin bridge – yellow insert). B Immunofluorescence of cell cycle-synchronized wt and Tcea1^–/– MEFs. Images show cells during the anaphase of the cell cycle (lagging chromosome - left arrow, chromatin bridge - right arrow). C Percentage of wt and Tcea1^–/– MEFs at each cell cycle phase (n = 3). Percentage of wt and Tcea1^–/– MEFs with (D). Anaphase bridges (n = 3). E Lagging chromosomes (n = 3). F At least one fusion event (n = 3, metaphases >20/genotype). G Telomeric sequences on a chromatin bridge of Tcea1^–/– MEFs (white arrows). H Quantitative FISH of untreated and NAC-treated wt and Tcea1^–/– MEFs for telomeric DNA (n = 3). The graph depicts the mean fluorescence intensity (MFI) per cell nucleus. I Immunostaining of γΗ2ΑΧ with FISH for telomeric DNA in Tcea1^–/– metaphase spreads. White arrows denote γH2AX signal on telomeres. J Wt and Tcea1^–/– metaphase spreads, in the presence or absence of SCR130 inhibitor. Telomeric DNA was detected by FISH (n = 3, metaphases >50/condition). White arrow in yellow frames: 1: chromosomes with telomere fusion. 2: chromosome with fragile telomere. 3: chromosome with short telomere. 4: chromosome with missing telomere. The graphs depict the percentage of metaphases with at least one fusion event (left), missing/short telomere (middle) or fragile telomere (right). K Telomeric DNA MFI per chromatid end of wt and Tcea1^–/– MEFs. Dotted line represents the shortest wt telomere (n = 3). Data analysis was performed using two-tailed Student’s t test. All data are presented as mean values ± SEM. Unless otherwise indicated, n = biologically independent experiments and scale bars are set at 5 μm. Source data are provided as a Source Data file.