MOF-mediated H4K16ac is critical for blastocyst formation in sheep by shaping promoter accessibility and transcription

Extending culture to blastocysts in vitro enhances embryo selection efficiency and implantation success in mammals, yet the epigenetic mechanisms underlying blastocyst formation remain unclear. Here, we investigate the role of histone acetyltransferase MOF-mediated H4K16ac during sheep blastocyst formation. We find dynamic changes in H4K16ac distribution during development, with a significant increase from the 8-cell stage to blastocyst and stage-specific enrichment in promoters. Inhibition of MOF activity reduces blastocyst formation and induces widespread transcriptional dysregulation and loss of H4K16ac at 3044 genomic peaks. Genes with these peaks are down-regulated and enriched for pathways critical to blastocyst formation. Notably, the lost H4K16ac peaks show reduced chromatin openness and lower RNA polymerase II (Pol2) enrichment, demonstrating the essential role of MOF in RNA Pol2 occupancy during blastocyst formation. Our findings indicate that MOF-mediated H4K16ac is critical for ovine blastocyst formation by promoting chromatin accessibility and RNA Pol2 occupancy at promoters, thereby facilitating appropriate transcriptional programs.