MIB1-mediated H2AK119 mono-ubiquitination chromatin landscapes independent of canonical PRC1

Polycomb repressive complex 1 (PRC1) is a central regulator of transcriptional repression through RING1B-mediated mono-ubiquitination of histone H2A at lysine 119 (H2AK119ub). Recent studies have suggested that the E3 ubiquitin ligase MIB1, previously characterized in Notch signaling, may also contribute to H2AK119ub deposition through a PRC1-independent mechanism. To investigate the chromatin-associated roles of MIB1, we generated ChIP-seq datasets for MIB1, RING1B, and H2AK119ub in the human colorectal cancer cell line HCT116. These datasets enable comparative analysis of genome-wide binding patterns, identification of shared and distinct target regions, and assessment of PRC1-dependent and PRC1-independent modes of H2AK119ub regulation. Overall design: ChIP-seq was performed in HCT116 colorectal cancer cells. H2AK119ub was profiled using an H2AK119ub-specific antibody, with MIB1 and RING1B analyzed by anti-FLAG ChIP following overexpression of FLAG-tagged MIB1 or FLAG-tagged RING1B.