Fig. 2

Direct and indirect models of recruitment of PRC2 by Xist RNA. a In the direct model, Xist localization brings PRC2 onto the chromatin by direct recruitment (upper panel). The PRC2 complex then places the H3K27me3 mark on the chromatin (middle panel), and this is followed by chromatin remodeler recruitment and chromatin compaction (lower panel). b In the indirect model, Xist interacts with gene-dense regions (upper panel) and induces chromatin changes (middle panel; i.e. histone deacetylation induced by Hdac3, chromatin compaction, eviction of RNA polymerase II). These changes might, in turn, recruit PRC1 or PRC2 and remodeler complexes (lower panel). H3K27me2-3 dimethylated or trimethylated histone 3 lysine 27, PRC1 polycomb repressive complex 1, PRC2 polycomb repressive complex 2