Practice question

Differentiation involves stable shutdown of stemness genes and activation of lineage-specific programs through coordinated chromatin remodeling processes. Histone acetylation by p300 and CBP opens embryonic enhancers to allow transcription, while subsequent deacetylation and H3K27 trimethylation via PRC2 polycomb complex closes pluripotency loci. DNA methylation by DNMT3A and DNMT3B at Oct4 and Nanog promoters locks commitment irreversibly. Heterochromatin protein 1-mediated heterochromatin formation silences repetitive elements and alternative lineages. All these modifications including acetylation changes, methylation patterning, and repressive compaction collectively drive progressive developmental restriction effectively.