SRP342671 PRJNA773661 GSE186374 PR-DUB safeguards Polycomb repression through restricting H2AK119ub1 [RNA-seq] Polycomb group (PcG) proteins are critical chromatin regulators for cell fate control. The mono-ubiquitylation on histone H2AK119 (H2AK119ub1) is one of the well-recognized mechanisms for Polycomb Repressive Complex 1 (PRC1)-mediated transcription repression. However, the specific H2AK119 deubiquitylation complex composed by ASX-like proteins (ASXLs) and BAP1 has also been genetically characterized as a Polycomb Repressive complex (PR-DUB). Here we try to provide a rationale for these counterintuitive findings. Through re-examining the genomic distribution of H2AK119ub1, we find that H2AK119ub1 is non-negligibly distributed at non-promoter regions and associated with PRC1 sampling. Upon deletion of Asxl2 in mouse embryonic stem cells (ESCs), H2AK119ub1 is pervasively gained, especially at non-promoter regions, which is associated with increased RING1B occupancy. Meanwhile RING1B is significantly lost from a subset of the target promoters and thereby results in minor derepression in Asxl2-null ESCs. However notably, Asxl2 loss causes aberrant lineage differetiation, similar to PcG mutants. Therefore, our data reconcile seemingly paradoxical roles of PR-DUB on transcription repression and highlight the importance of a balanced H2AK119ub1 dynamics in developmental regulation. Overall design: Examination of expression levels between WT and Asxl2KO during ESC to MES differentiation. GSE186374 pubmed 36959757 parent_bioproject PRJNA773657