PRC1 Catalytic Activity Is Central to Polycomb System Function

• Published in: Molecular cell Vol. 77; no. 4; pp. 857 - 874.e9
• Main Authors: Blackledge, Neil P., Fursova, Nadezda A., Kelley, Jessica R., Huseyin, Miles K., Feldmann, Angelika, Klose, Robert J.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 20.02.2020; Cell Press
• Subjects: Animals; Biocatalysis; Cell Line; chromatin; Chromatin - metabolism; conditional point mutant; Embryonic Stem Cells - enzymology; Embryonic Stem Cells - metabolism; gene expression; Gene Expression Regulation; H2AK119ub1; HEK293 Cells; histone modification; Histones - metabolism; Humans; Male; Mice; Point Mutation; polycomb; Polycomb Repressive Complex 1 - genetics; Polycomb Repressive Complex 1 - metabolism; Polycomb Repressive Complex 2 - metabolism; PRC1; transcription; Ubiquitin-Protein Ligases - genetics; Ubiquitin-Protein Ligases - metabolism; conditional point mutant; transcription; histone modification; PRC1; polycomb; chromatin; gene expression; H2AK119ub1
• ISSN: 1097-2765; 1097-4164; 1097-4164
• DOI: 10.1016/j.molcel.2019.12.001

The Polycomb repressive system is an essential chromatin-based regulator of gene expression. Despite being extensively studied, how the Polycomb system selects its target genes is poorly understood, and whether its histone-modifying activities are required for transcriptional repression remains controversial. Here, we directly test the requirement for PRC1 catalytic activity in Polycomb system function. To achieve this, we develop a conditional mutation system in embryonic stem cells that completely removes PRC1 catalytic activity. Using this system, we demonstrate that catalysis by PRC1 drives Polycomb chromatin domain formation and long-range chromatin interactions. Furthermore, we show that variant PRC1 complexes with DNA-binding activities occupy target sites independently of PRC1 catalytic activity, providing a putative mechanism for Polycomb target site selection. Finally, we discover that Polycomb-mediated gene repression requires PRC1 catalytic activity. Together these discoveries provide compelling evidence that PRC1 catalysis is central to Polycomb system function and gene regulation. [Display omitted] •PRC1 catalysis drives PRC2 occupancy and H3K27me3 deposition at target sites•cPRC1 binding and PRC1-mediated chromatin interactions require PRC1 catalysis•DNA-binding vPRC1 complexes occupy target sites independently of PRC1 catalysis•PRC1 catalytic activity is essential for Polycomb-mediated gene repression In this study, Blackledge et al. generate a conditional catalytic point mutant system to test the contribution of PRC1 catalytic activity to the Polycomb repressive system. They reveal that PRC1 catalytic activity is essential for Polycomb chromatin domain formation, long-range chromatin interactions between Polycomb target sites, and Polycomb-mediated gene repression.