Proximity-dependent recruitment of Polycomb Repressive Complexes by the lncRNA Airn [CHART-Seq]

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. Capture Hybridization Analysis of RNA Targets coupled with sequencing (CHART-Seq) in TSCs and ESCs.