4sUDRB-sequencing for genome-wide transcription bursting quantification in breast cancer cells

Systematic characterisation of the genomic and epigenetic chromatin context of genes with defined transcription bursting behaviour has been incomplete. Here, we measured the bursting of transcription itself by genome-wide nascent RNA sequencing of breast cancer MCF-7 cells upon synchronisation of transcription with a transcription elongation inhibitor (DRB). After 3 hours of transcription inhibition, cells were washed and allowed to transcribe in the presence of 4sU, with samples taken after 0, 5, 10, 15, 20, 30 and 40 minutes. Cells mock treated with DMSO only (not DRB) were also allowed to transcribe for 40 minutes in the presence of 4sU. Nascent 4sU-containing RNA were then enriched and sequenced.