Extended Data Fig. 5. Epigenetic alterations in micronuclei.
(a) Modest increase of repressive chromatin marks in a subset of late S/G2 MN. Performed and analyzed as in Extended Data Fig. 4a (n = 129, 179, 114 and 105, left to right, from two experiments for H3K9me2; from one or two experiments for H3K27me3). (b) Left, selected example images from (a) of cells with ruptured MN that show apparent enrichment for H3K9me2 and HK27me3 in the MN. Arrowheads: micronuclei lacking normal RFP-NLS accumulation. Right: related to (a) but comparing intact and ruptured MN for H3K9me2 (n = 48 and 40, left to right, from two experiments) and H3K27me3 (n = 35 and 26, left to right, from two experiments) at 23 h post mitotic shake-off. Performed and analyzed as in Extended Data Fig. 4a. Scale bars 5 µm. (c) Loss of H3K9ac and H3K27ac in MN at the indicated timepoint during interphase. Left: representative images of the indicated histone modifications at 2 h post mitotic shake-off. Right: quantification and analysis of data for H3K9ac as in Fig. 1e (n = 148 and 124, left to right, from two experiments). Scale bars 5 µm. (d) HDAC inhibition is not sufficient to rescue the transcription defect of chromosomes in micronuclei. Cells were analyzed after incubation with a pan-HDAC inhibitor (SAHA) for 23 h post release from a nocodazole block followed by a mitotic shake-off (n = 302 and 335, left to right, from three experiments for both H3K27ac and RNAP2-Ser5ph). For the intact micronuclei, a significant rescue of H3K27ac levels was also observed after HDACi treatment (0.36 and 0.87 MN:PN for H3K27ac in DMSO and HDACi groups, respectively, P < 0.0001) and this was also not detectably accompanied by rescue of the transcription defect (0.14 and 0.07 MN:PN for RNAP2-Ser5ph in DMSO and HDACi groups, respectively) (n = 165 and 131 for both H3K27ac and RNAP2-Ser5ph). Performed and analyzed as in Fig. 1e. All pairwise comparisons between DMSO and HDACi have P < 0.0001. For the intact MN, all pairwise comparisons between MN and PN have P < 0.0001, except for the HDACi of H3K27ac group that has P = 0.502.