Heritable human Polycomb silencing is locus-dependent and requires H2AK119ub1 self-propagation

Heritable gene silencing is essential for the development of multicellular organisms. Polycomb repressive complexes 1 and 2 (PRC1 and 2) catalyze and recognize histone H2A lysine 119 mono-ubiquitination (H2AK119ub1) and histone H3 lysine 27 trimethylation (H3K27me3), respectively, to mediate heritable gene silencing, but the mechanism of inheritance is not fully understood. Using an inducible gene silencing strategy, we show that the epigenetic inheritance of Polycomb silencing in human cells is strongly dependent on local DNA sequences and chromatin environment. In addition, we find that inheritance is not strictly dependent on H3K27me3 recognition and can be partially achieved by H2AK119ub1 catalysis and recognition, independently of H3K27me3. These findings demonstrate that locus specific features and H2AK119ub1 play key roles in inheritance of Polycomb silencing in human cells.