Coordination of widespread transcription at enhancers and target genes through BRD4 (ChIP-Rx)

Gene transcription by RNA polymerase II (Pol II) is under the control of promoters and distal regulatory elements known as enhancers. Enhancers are themselves transcribed by Pol II which correlates with their activity. How enhancer transcription is regulated and coordinated with transcription at target genes has remained unclear. Here, we developed a high-sensitive native elongating transcript sequencing approach, called HiS-NET-seq, to provide an extended high-resolution view on transcription, especially at lowly transcribed regions such as enhancers. HiS-NET-seq uncovers new transcriptional enhancers in human cells. An integrated multi-omics analysis shows that transcription at most enhancers depends on the BET protein BRD4. We provide evidence for a direct BRD4-mediated coupling of Pol II transcription at enhancers and target genes. Specifically, BRD4 links elongation activation at enhancers and genes by maintaining their proximity. These studies reveal that transcription at enhancers and target genes is coordinated at the level of elongation. Overall design: Pol II occupancy profiling using standard NET-seq or HiS-NET-seq data for K562 WT cells and upon BRD4-specific degradation in K562 dTAG-BRD4 cells.