Figure 5.

Variant PRC1 Complexes Occupy Polycomb Target Sites Independently of PRC1 Catalysis

(A) Heatmap analysis of cChIP-seq for H3K27me3, H2AK119ub1, RING1B, PCGF2, PCGF1, and PCGF6 at RING1B-bound sites in PRC1^CPM cells. Also shown is BioCAP-seq (measure of non-methylated CpG-rich DNA) and ChIP-seq for MAX and H3K4me3 in wild-type ESCs. Genomic intervals were sorted based on log2 fold change in RING1B occupancy following OHT treatment in PRC1^CPM ESCs.

(B) Maximum intensity projections of RING1B-Halo-JF₅₄₉ signal in PRC1^CPM ESCs. Examples of RING1B nuclear foci are indicated by arrowheads. Scale bar is 5 μm.

(C) Boxplots comparing the number of all (left panel) or top 25% highest intensity (right panel) RING1B-Halo-JF₅₄₉ foci per nucleus in PRC1^CPM ESCs before (n_cells = 69) and after (n_cells = 83) OHT treatment. Cells from two independent experiments were analyzed. P values denote statistical significance calculated by a Student’s t test.

(D) Genomic snapshots of two genes showing cChIP-seq for RING1B, PCGF1, PCGF6, and PCGF2 in PRC1^CPM ESCs. H2AK119ub1 cChIP-seq in untreated cells and H3K4me3 ChIP-seq in wild-type ESCs is also shown. Cbln2 is a lowly transcribed gene with high-level RING1B occupancy and Ptges3 is a more highly transcribed gene.

(E) Correlation of cChIP-seq signal for RING1B with PRC2 (SUZ12 and H3K27me3) and PRC1 (PCGF2, PCGF1, PCGF6, and H2AK119ub1) in untreated and OHT-treated PRC1^CPM ESCs. Correlation with BioCAP-seq and ChIP-seq for MAX and H3K4me3 in wild-type ESCs is also shown.

(F) Relative enrichment of RING1B, PCGF1, PCGF6, and PCGF2 cChIP-seq signal in PRC1^CPM ESCs across promoter-proximal RING1B-bound sites divided into percentiles based on the expression level of the associated gene in untreated PRC1^CPM cells. For each factor, enrichment is shown relative to the fiftieth percentile. Lines represent smoothed conditional means based on loess local regression fitting.

See also Figure S5.