Genome-wide analysis of H3.3 dissociation in mouse embryonic stem cells. Mus musculus

Using Tet-inhibited expression of epitope-tagged H3.3 combined with ChIP-Seq we undertook genome-wide measurements of H3.3 dissociation rates across the ESC genome and examined the relationship between H3.3-nucleosome turnover and ESC-specific transcription factors, chromatin modifiers and epigenetic marks. Overall design: To measure dissociation rates of H3.3, we utilized a TET-repressible ESC line, ES[MC1R(20)], with the expression cassette integrated at the ROSA26 locus. We transfected MC1R ESCs with HA/FLAG-tagged H3.3 controlled by tetracycline response elements. For ‘TET-OFF’ experiments, ESCs were cultured over several passages (weeks) on feeder cells in the absence of DOX and were subsequently passaged onto feeder-free plates prior to the inhibition of HA-H3.3 expression. To repress HA/FLAG-H3.3 expression we treated cells with 2 μg/ml doxycycline hyclate before crosslinking with formaldehyde at various time points. Measurement of H3.3-HA enrichment over time-course was performed using two replicates of ChIP-seq experiments. As a control, input DNA sequencing was performed for every time point