Fig. 6: Branched F-actin promotes abscission by favoring MT severing.

a Top: Staining of endogenous ARPC2, IST1 and Tubulin in a late ICB with secondary ingression (arrowhead). Scale bar = 2 μm. Bottom: Intensity profile of ARPC2 (magenta) and IST1 (green) between * and ** along the ICB from the top merge picture. This experiment was repeated at least three times independently with similar results. b Snapshots of a spinning disk confocal microscopy movie of cells stably co-expressing CHMP4B-GFP and mApple-ARPC4 and incubated with fluorescent SiR-Tubulin. Arrowheads: ARPC4 localization at the tip of the CHMP4B cone. Scale bar = 2 μm. c Left: Cumulative distribution of the fraction of cells that completed abscission (determined by phase contrast time-lapse microscopy) as function of time after complete furrow ingression in cells treated, after furrow ingression, with either DMSO or CK666 (n ≥ 195 cells per condition from 3 independent experiments). Note that DMSO and 160 μM CK666 were added after furrow ingression in synchronized cells (see Methods). Right: Mean abscission time (min) ± SD in indicated cells, n ≥ 61 cells per condition, N = 3 independent experiments. Two-tailed unpaired Student’s t-test. d Same analysis as in Fig. 4b in cells treated with either DMSO or CK666 after complete furrow ingression, as indicated. Left: n ≥ 150 cells per condition from 3 independent experiments. Middle and right: n ≥ 41 cells per condition, N = 3 independent experiments. Two-tailed paired Student’s t-test. n.s. = non-significant (p > 0.05). e Same analysis as in Fig. 4d in cells treated with either DMSO or CK666, together with DMSO or 2 μM Batabulin after complete furrow ingression, as indicated. Left: n ≥ 89 cells per condition from 3 independent experiments. Right: n ≥  21 cells per condition, N = 3 independent experiments. One-way ANOVA with Tukey’s multiple comparisons test. n.s. = non-significant (p > 0.05).