Figure 7. Cep57 truncation leads to aberrant spindles that missegregate chromosomes.

(A) Representative images of metaphase microtubule configurations and intensity in MEFs. Right: Quantification of spindle abnormalities. (B) Quantification of spindle intensities as seen in A. (C) Quantification of spindle α-tubulin intensity in human fibroblasts of indicated genotypes. (D) Microtubule regrowth assay on Cep57-insufficient cells. Left: Images of mitotic MEFs of the indicated genotypes placed on ice for 40 minutes and stained for α- and γ-tubulin after the indicated recovery times at 37°C. Right: Quantification of α-tubulin signals in MEFs of the indicated genotypes. (E) Measurement of metaphase plate width in MEFs of indicated genotypes/subgroups. (F) Percentage of cells undergoing indicated chromosome missegregation error determined by live-cell imaging on MEFs expressing H2B-mRFP. (G) Percentage of cells observed to form micronuclei after a chromosome missegregation event, per analyses performed in E. (H) Percentage of P5 MEFs with abnormal number of chromosomes counted on metaphase spreads. Polyploid cells were excluded. Analyses in A, B, and D were performed on at least 3 independent lines per genotype (20 cells per line). Analysis in C was performed on 1 cell line per genotype (20 cells analyzed per line). The experiment was repeated 3 times. Analyses in E and F were performed on at least 3 independent lines per genotype (at least 25 cells per line). Analysis in G was performed on at least 3 lines per genotype (50 cells per line). Data in A–H represent the mean ± SEM. Statistical significance in A, E, and H was determined using 1-way ANOVA followed by Tukey’s multiple-comparisons test. Statistical significance in C, D, F, and G was determined using a 2-tailed unpaired t test, and in B using a 1-tailed unpaired t test. *P < 0.05, **P < 0.01, ***P < 0.001. Scale bars: 5 μm.