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. Author manuscript; available in PMC: 2022 Dec 2.
Published in final edited form as: Nat Biomed Eng. 2021 Dec 2;5(12):1500–1516. doi: 10.1038/s41551-021-00823-9

Fig. 3: Culture of both contractile CMs and non-contractile cells in vitro show opposing enrichment of H3K9 and H3K27 trimethylated chromatin.

Fig. 3:

Embryonic cardiac cells were isolated from H2b-eGFP embryo hearts and cultured on soft (13 kPa) PDMS substrates. a) After two days in culture, contractile CMs (C) with distinct myofibrils showed peripheral accumulation of H3K9me3-modified chromatin while non-contractile cells (N) showed a homogenous distribution of H3K9me3 clusters. b) Cells were stained for H3K27me3 and H3K9me3 (and actin, Extended Fig. 3a) and images of nuclei from CMs or non-contractile cells (NCCs) were acquired at day two or four of culture. c) Stained nuclei were analyzed for peripheral enrichment of overall (H2b) or epigenetically marked chromatin. Intensity of each channel was analyzed with respect to its relative distance to the nuclear center (1=periphery). Gray areas indicate the center bin (0.05–0.15) and the peripheral bin (0.85–0.95) used to calculate enrichment scores. SEM; n>60 from 5 exp. d) Enrichment scores (marker intensity of the peripheral bin divided by the center bin) were calculated. CMs, but not non-contractile cells (NCC), displayed reorganization of chromatin towards the periphery at day four, which was preceded by enrichment of H3K9me3-marked chromatin at day two. SEM; n>60 from 5exp.; T-test (HM=1): *** p<0.001; all scales=5 µm.