Physical and functional screening of Polycomb Repressor Complex 2 highlights novel regulators of histone H3 lysine 27 methylation status

Polycomb Repressor Complex 2 (PRC2) is a multi-protein epigenetic regulator complex that plays critical roles in early development and tissue differentiation. The complex catalyzes the methylation of histone H3 lysine 27 (H3K27). The tri-methyl state (H3K27me3) is well studied as an agent of gene repression, but more recently distinct roles for the mono- and di-methyl states have been discovered. In order to more fully understand how PRC2-associated factors might influence H3K27 status, we screened for physical associations of PRC2 subunits. Knockdown of these factors was used to produce functional interaction maps focused on H3K27 methylation, including proteins that have positive and negative effects on the levels each histone mark.