Extended Data Fig. 8: Schematic model illustration of the stepwise establishment of facultative heterochromatin at CGIs, putative enhancers, and the paternal X-chromosome (Xp).

a. At CGI promoters of many Polycomb-targeted developmental genes, H2AK119ub1 is gained at the two-cell stage, and H3K27me2 and 3 are gained at the morula and the blastocyst stages, respectively, catalysed by PRC2.2. In Jarid2 KO morula embryos, H3K27me2 fails to be deposited at CGIs and distal regions, resulting in an increase of H3K27ac at putative enhancers. In Jarid2 KO and DKO blastocysts, H3K27me3 fails to be deposited with the DKO being more prominent. By contrast, H3K27me3 is deposited at CGIs in Aebp2 KO blastocysts. b. Across Xp, H2AK119ub1 is progressively accumulated from the eight-cell stage, while H3K27me2 and 3 are accumulated from the morula and the blastocyst stages, respectively, in a PRC2.2-dependent manner. H3K27me2 fails to accumulate at Xp in Jarid2 KO morula embryos. In both Jarid2 KO and Aebp2 KO blastocysts, H3K27me3 fails to accumulate, but it is locally deposited at CGIs in the Aebp2 KO. H3K27me3 deposition is abrogated in DKO blastocysts.