Proximity-dependent recruitment of Polycomb Repressive Complexes by the lncRNA Airn [Hi-C]

In the developing mouse embryo, expression of the lncRNA Airn induces gene silencing and recruits Polycomb Repressive Complexes (PRCs) to varying extents over a 15 megabase domain, but the mechanisms remain unclear. Using high-resolution approaches, we show in mouse trophoblast stem cells that Airn expression induces long-range changes to chromatin architecture centered around a network of CpG islands occupied by PRCs and SMC1A/Cohesin. Extent of contact with Airn predicts underlying intensity of Polycomb-directed chromatin modifications and Airn-induced changes to chromatin architecture. Deletion of individual CpG islands alternately increase or decrease gene silencing and PRC activity over the domain in a manner predicted by changes in chromatin architecture. We conclude that Airn is a potent repressive lncRNA whose effects are controlled by an equilibratory network of DNA regulatory elements that modulate its frequency of contact with target chromatin. HiC in TSCs