Inhibition of SWI/SNF broadly disrupts enhancers and reveals remodeler redundancy at promoters

Appropriate gene expression requires the establishment of accessible chromatin at promoters and enhancers. These patterns are maintained thorugh the action of, such as the SWI/SNF family. Despite this critical role, previous studies have remained inconclusive regarding the direct role of SWI/SNF. Herein, we employ BRM014, a fast-acting small-molecule inhibitor of the SWI/SNF ATPase subunit, to probe the direct response of mouse embryonic stem cells to disruption of appropriate SWI/SNF chromatin remodeling activity. We demonstrate that the immediate role of SWI/SNF inhibition is a broad loss of chromatin accessibility at both promoter and enhancer loci, and this is reflected in an associated reduction in nascent transcription. We determine that this initial perturbation can be compensated for at a majority of gene promoters, such that these elements regain accessibilty and gene expression under prolonged treatment. However, a subset of gene promoters, as well as most enhancers, fail to recover under these conditions. Finally, we identify EP400 as a putative factor driving compensation ability, as the loss of this factor impedes promoter recovery. Overall design: ATAC-seq, PRO-seq, ChIP-seq, RNA-seq. For all experiments, at least two replicates were generated for each condition. Comparative gene expression profiling analysis of RNA-seq data for A548 and H1299 cells following 12 h treatment with 5 uM BRM014 or DMSO control.