LAUSR

Polycomb group proteins are important for maintaining gene expression patterns and cell identity in metazoans. The mammalian Polycomb repressive de-ubiquitinase (PR-DUB) complexes catalyze removal of monoubiquitination on lysine 119 of histone H2A (H2AK119Ub1) through a multi-protein core comprised of BAP1, HCFC1, FOXK1/2, and OGT in combination with either of ASXL1, 2 or 3. Mutations in PR-DUB components are frequent in cancer. However, mechanistic understanding of PR-DUB function in gene regulation is limited. Here, we show that BAP1 is dependent on the ASXL proteins and FOXK1/2 in facilitating gene activation across the genome. Although PR-DUB previously was shown to cooperate with PRC2, we observed minimal overlap and functional interaction between BAP1 and PRC2 in embryonic stem cells. Collectively, these results demonstrate that PR-DUB, by counteracting accumulation of H2AK119ub1, maintains chromatin in an optimal configuration ensuring expression of genes important for general functions such as cell metabolism and homeostasis.