ChIP-chip of siGFP- or siHOTAIR-treated foreskin fibroblasts with anti-H3K4me2, anti-LSD1 or anti-SUZ12 antibodies on HOX tiling array

Long intergenic noncoding RNAs (lincRNAs) regulate chromatin states and epigenetic inheritance. Here we show that the lincRNA HOTAIR serves as a scaffold for at least two distinct histone modification complexes. A 5’ domain of HOTAIR binds Polycomb Repressive Complex 2 (PRC2) while a 3’ domain of HOTAIR binds the LSD1/CoREST/REST complex. The ability to tether two distinct complexes enables RNA-mediated assembly of PRC2 and LSD1, and coordinates targeting of PRC2 and LSD1 to chromatin for coupled histone H3 lysine 27 methylation and lysine 4 demethylation. Our results suggest that lincRNAs may serve as scaffolds by providing binding surfaces to assemble select histone modification enzymes, and thereby specify the pattern of histone modifications on target genes. Coordinate loss of SUZ12 and LSD1 occupancy caused by HOTAIR knockdown were concentrated in proximal promoters of HOXD genes. These regions correspondingly lost H3K27me3 and gained H3K4me2, the respective histone methylation products of PRC2 and LSD1 complexes.