Hormone-responsive enhancer-activity maps reveal predictive motifs, indirect repression, and targeting of closed chromatin
Steroid hormones act as important developmental switches and their nuclear receptors regulate many genes. However, few hormone-dependent enhancers have been characterized and important aspects of their sequence architecture, cell type-specific activating and repressing functions, or the regulatory roles of their chromatin structure have remained unclear. We used STARR-seq, a recently developed enhancer-screening assay, and ecdysone signaling in two different Drosophila cell types to derive the first genome-wide hormone-dependent enhancer activity maps. We demonstrate that enhancer activation depends on cis-regulatory motif combinations that differ between cell types and can predict cell type-specific ecdysone targeting. Activated enhancers are often not accessible prior to induction. Enhancer repression following hormone treatment is independent of receptor motifs and receptor binding to the enhancer as we show using ChIP-seq, but appears to rely on motifs for other factors, including Eip74. Our strategy is applicable to study signal-dependent enhancers for different pathways and across organisms. Overall design: STARR-seq was performed in S2 and OSC cells treated with ecdysone in two replicates. DHS-seq before and after treatment was done with single-end sequencing in two replicates. RNA-seq (with and without ecdysone) was performed with a strand-specific protocol using single-end sequencing in two replicates in S2. ChIP-seq (with and without ecdysone) was performed single-end sequencing in two replicates in S2 cells.