Fig. 4: PRC1 condensates recognize and write repressive histone marks. | Nature Communications

Fig. 4: PRC1 condensates recognize and write repressive histone marks.

From: Polycomb condensates can promote epigenetic marks but are not required for sustained chromatin compaction

Fig. 4

a The Cbx subunit of PRC1 recognizes the H3K27me3 mark, and the RING subunit writes the H2AK119Ub mark. b Immunofluorescence on the H3K27me3 mark in fixed CBX2-mCh-sspB Corelet cells, before (OFF) and after (ON) activation. CBX2-mCh-sspB colocalizes with H3K27me3 marks upon light activation (n = 38/38/36/36 cells for 0/5/10/20 min for Cbx2, n = 18/9/7/5 cells for 0/5/10/20 min for mCh). The CBX2_F12A-mCh-sspB mutant is unable to recognize the H3K27me3 mark (n = 18 cells at 20 min). Scale bar is 5 µm. Data are presented as mean values +/− SD. c Immunofluorescence staining of the H2AK119Ub mark in fixed CBX2-mCh-sspB Corelet cells, before (OFF) and after (ON) activation. CBX2-mCh-sspB colocalizes with H2AK119Ub marks upon light activation (n = 40/41/31/37 cells for 0/5/10/20 min for Cbx2, n = 14/8/4/14 cells for 0/5/10/20 min for mCh). Data are presented as mean values +/− SD. d Immunofluorescence staining of the H3K27me3 mark in fixed RNF2-mCh-sspB Corelet cells, before (OFF) and after (ON) activation. RNF2-mCh-sspB colocalizes with H3K27me3 marks upon light activation (n = 28/29/30/25 cells for 0/5/10/20 min for Cbx2, n = 18/9/7/5 cells for 0/5/10/20 min for mCh). Data are presented as mean values +/− SD. e Immunofluorescence staining of the H2AK119Ub mark in fixed RNF2-mCh-sspB Corelet cells, before (OFF) and after (ON) activation. RNF2-mCh-sspB colocalizes with H2AK119Ub marks upon light activation (n = 42/29/29/36 cells for 0/5/10/20 min for Cbx2, n = 14/8/4/14 cells for 0/5/10/20 min for mCh). The RNF2_D56K-mCh-sspB mutant shows less colocalization with the H2AK119Ub mark (n = 32 cells at 20 min). Data are presented as mean values +/− SD. f Schematic of local activation experiment. Each cell is locally activated in a 1 micron2 area for 20 min, after which the cells are rapidly fixed. Fixed cells are immunostained with anti-H2AK119ub antibody and stained with Hoechst. g Local activation of RNF2-mCh-sspB. Arrows indicate region of interest. Scale bar is 5 µm. h Fixed cells after local activation of RNF2-mCh-sspB, stained with Hoechst and anti- H2AK119Ub immunofluorescence. Scale bar is 5 µm.

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