SRA

The three-dimensional (3D) organization of the genome within the cell nucleus contributes to cell-specific gene expression in different cell types1. High-throughput 3C–derived methods have revealed that the genome is segmented into contiguous topologically associating domains (TADs), which help to orchestrate gene expression changes during differentiation and development2-5. Using ChIP-Seq, Hi-C and 3D modelling techniques, we reveal that TADs regulate the rapid gene expression changes induced by progestin in T47D breast cancer cells. In response to the hormone, TADs maintain their borders and operate as discrete regulatory units in which the majority of the genes are either transcriptionally activated or repressed. Additionally, the epigenetic signatures of the TADs are coordinately modified by hormone in correlation with the transcriptional changes. Hormone-induced changes in gene activity and chromatin remodelling are accompanied by structural changes that are distinct for activated or repressed TADs. Integrative 3D modelling revealed that TADs are structurally expanded if active and compacted if repressed, and that this is accompanied by differential changes in accessibility. We thus propose that TADs function as “regulons” to enable spatially proximal genes to be coordinately transcribed in response to hormones. Overall design: T47D-MTVL human breast cancer cells were incubated with the progestin R5020 for different times at 37ºC and prepared for ChIP-Seq or Hi-C according published protocols