RT Journal Article SR Electronic T1 Distinct stimulatory mechanisms regulate the catalytic activity of Polycomb Repressive Complex 2 (PRC2) JF bioRxiv FD Cold Spring Harbor Laboratory SP 210542 DO 10.1101/210542 A1 Chul-Hwan Lee A1 Marlene Holder A1 Daniel Grau A1 Ricardo Saldana-Meyer A1 Rais Ahmad Ganai A1 Jenny Zhang A1 Miao Wang A1 Marc-Werner Dobenecker A1 Danny Reinberg A1 Karim-Jean Armache YR 2017 UL http://biorxiv.org/content/early/2017/10/28/210542.abstract AB The maintenance of gene expression patterns during metazoan development is carried out, in part, by the actions of the Polycomb Repressive Complex 2 (PRC2). PRC2 catalyzes mono-, di-and trimethylation of histone H3 at lysine 27 (H3K27), with H3K27me2/3 being strongly associated with silenced genes. We demonstrate that EZH1 and EZH2, the two mutually exclusive catalytic subunits of PRC2, are differentially activated by various mechanisms. While both PRC2-EZH1 and PRC2-EZH2 are able to catalyze monomethylation, only PRC2-EZH2 is strongly activated by allosteric modulators and specific chromatin substrates to catalyze di-and trimethylation of H3K27. However, we also show that a PRC2 associated protein, AEBP2, can stimulate the activity of both complexes through a mechanism independent of and additive to allosteric activation. These results have strong implications regarding the cellular requirements for and accompanying adjustments in PRC2 activity, given the difference in the expression of EZH1 and EZH2 upon cellular differentiation.