INO80 promotes and safeguards bivalency [ChIP-seq]

INO80 is involved in many chromatin-dependent functions. However, its role in pluripotency has not been fully defined. We examined the impact of Ino80 deletion in the naïve and primed pluripotent stem cells. We found that Ino80 deletion had minimal effect on self-renewal and gene expression in the naïve state, but led to cellular differentiation and de-repression of developmental genes in the primed state. Mechanistically, INO80 co-occupied gene promoters that were bivalently marked by H3K4me3 and H3K27me3. Further, its occupancy was required for H3K27me3 installation and maintenance, as well as downstream gene repression. Finally, INO80 promoted H2A.Z occupancy at the bivalent domains, which in turn facilitated the polycomb repressive complex 2 (PRC2) recruitment. Together, our results identified the INO80-H2A.Z axis as an essential step for bivalent chromatin and poised gene expression and uncovered an epigenetic mechanism by which chromatin remodeling, histone variant, and histone modification coordinately control cell fate. Effects of INO80 deletion on the transcriptome (RNAseq) and epigenome (ChIP-seq, MNase-seq) in mouse naïve and primed pluripotent stem cells