GSE118047
Ecdysone-induced 3D chromatin reorganization involves active enhancers bound by Pipsqueak and Polycomb
In Drosophila, Polycomb (Pc) has emerged as a loop-anchored associated protein, but further investigation of its directed chromatin architecture is needed. It is recruited to DNA by GAGA-binding factors GAF and Pipsqueak (Psq). psq encodes distinct isoforms that contain or lack a BTB oligomerization domain, but their contribution to the general epigenetic role of Psq in development and cancer is rarely considered. Here, we use HiChIP in Drosophila cells to characterize the Pc- and Psq-directed genome architecture. We show that PsqS isoforms lacking the BTB domain are consistently found at Pc loop anchors and at active enhancers, including those responsive to ecdysone. PsqS mediates ecdysone-induced enhancer-promoter interactions, coordinating expression of a selective set of genes by chromatin looping. BTB-Psq isoforms, on the other hand, bind at architectural protein binding sites. Our findings support a BTB-directed role of Psq at different types of regulatory elements, mediating selective responses to hormonal cues. Overall design: HiChIP, ChIP-seq