Fig. 5: Cep55 is required for abscission in neural progenitors but not in primary fibroblasts.

a Timeline for Cep55 deletion in Cep55^F/F; R26-Cre^ERT2/+ neural progenitor cells (NPCs), using 4-hydroxytamoxifen (4OHT) to induce recombination or ethanol (EtOH) as vehicle control. IFM, immunofluorescence microscopy; PCR, polymerase chain reaction; qPCR, quantitative PCR; WB, western blotting. b NPCs treated as shown in a were stained for DNA (DAPI) and α-tubulin. Arrows and arrowheads indicate binucleated and pyknotic cells, respectively, quantified in c. n = 3 mice per condition; 1000 cells quantified per condition. *P-values were calculated by one-way ANOVA followed by Tukey’s multiple comparisons test as follows: binucleated cells: P = 0.9703 for FF vs. FF + EtOH, P < 0.0001 for FF vs. FF + 4OHT, P < 0.0001 for FF + EtOH vs. FF + 4OHT; pyknotic cells: P = 0.9673 for FF vs. FF + EtOH, P = 0.0126 for FF vs. FF + 4OHT, P = 0.0165 for FF + EtOH vs. FF + 4OHT. d Timeline for culture and analysis of mouse primary tail tip fibroblasts (TTFs). FACS, fluorescence-activated cell sorting. e TTFs of the indicated genotypes collected as in d were stained as in b. Arrows indicate binucleated cells, quantified in f. n = 3 and 4 mice, respectively; 1300 Cep55^+/+ cells and 1800 Cep55^−/− cells quantified. g Representative time-lapse images of NPCs treated as in a. Arrowhead in the upper panel indicates the intercellular bridge; arrowhead in the lower panel indicates the attempt to divide possibly by cytofission⁴¹. h Quantification of dividing NPCs as defined in g. n = 3 mice per condition; 56 control cells (Cep55^F/F + EtOH) and 32 recombined cells (Cep55^F/F + 4OHT) were quantified. i Representative time-lapse images of TTFs cultured as in d. Arrowheads indicate the intercellular bridge. j Quantification of dividing Cep55^+/+ and Cep55^−/− TTFs as defined in i. n = 3 mice per genotype; 153 and 171 cells quantified, respectively. All bar charts show mean ± SD. P-values calculated using Student’s two-tailed unpaired t-test in f, h, j. Cep55^F/F indicates Cep55^F/F; R26-Cre^ERT2/+ allele in b, c, g, h, Cep55^−/− indicates Cep55^tm1a/tm1a allele in e and f, and Cep55^tm1d/tm1d allele in i and j. Source data for c, f, h, j are provided as a Source Data file.