Fig. 1

Nuclei from CIZ1-null cells fail to condense on entry to quiescence. A Nuclear area in cycling female and male populations of WT (green) and CIZ1-null (blue) primary embryonic fibroblasts (PEFs), demonstrating no difference in nuclear size. Dots represent individual nuclei, with mean (grey bar). Right, example workflow for quantification of nuclear area using Fiji image analysis; see the “Methods” section. B Serum withdrawal (SW) and add back (AB) strategy and their effect on S phase index. Histograms show the proportion of cells that incorporate EdU during a 30-min pulse (replicating, red). No difference is detected between WT and CIZ1-null cells. C Graphs show change in nuclear area over the SW and AB strategy for male and female WT and CIZ1-null PEFs, normalised to the means for the cycling control state. Representative images of WT and CIZ1-null nuclei at each stage are shown. Below, mean areas and calculated volumes assuming a spherical nucleus; see the “Methods” section. D Nuclear area for WT and CIZ1-null PEFs in a cycling state (day 0) and at 100% confluency (day 3) with no SW. E Immunodetection of the nuclear lamina (Lamin B2, red) in a representative CIZ1-null AB population. F Nuclear area for CIZ1-null PEFs over two rounds of SW and AB, showing failure to condense but stepwise decondensation. Representative images demonstrate the overexpansion of CIZ1-null nuclei. All results are either compared by t-test (A), one-way ANOVA (B, C, F) or two-way ANOVA (D) where ns denotes no significant difference, *p < 0.05, **p < 0.01, ***p < 0.001. DNA is stained with DAPI (blue) and scale bar represents 10 μm