Polycomb group proteins maintain the gene-expression pattern of different cells that is set during early development by regulating chromatin structure. In mammals, two main Polycomb group complexes exist — Polycomb repressive complex 1 (PRC1) and 2 (PRC2). PRC1 compacts chromatin and catalyses the monoubiquitylation of histone H2A. PRC2 also contributes to chromatin compaction, and catalyses the methylation of histone H3 at lysine 27. PRC2 is involved in various biological processes, including differentiation, maintaining cell identity and proliferation, and stem-cell plasticity. Recent studies of PRC2 have expanded our perspectives on its function and regulation, and uncovered a role for non-coding RNA in the recruitment of PRC2 to target genes.
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We are grateful to L. Vales, E. Heard and R. Bonasio for crucial reading of this manuscript and active discussions. We apologize to authors whose studies could not be cited owing to space limitations. Work in the laboratory of R.M. is supported by the Institut Nationale du Cancer and Fondation pour la Recherche Medicale. Work in the laboratory of D.R. is funded by the US National Institutes of Health (grants RO1GM064844 and 4R37GM037120) and the Howard Hughes Medical Institute.
The authors declare no competing financial interests.
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Margueron, R., Reinberg, D. The Polycomb complex PRC2 and its mark in life. Nature 469, 343–349 (2011). https://doi.org/10.1038/nature09784
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