RB is a cell cycle-regulated repressor of cohesin-dependent loop formation

Chromatin organization and cell cycle are tightly intertwined in eukaryotes, but the underlying mechanisms remain unclear. We investigated how the retinoblastoma protein (RB), a key cell cycle regulator, influences chromatin architecture. Chromosome conformation capture assays reveal that RB loss increases the number and size of cohesin-dependent loops and strengthens topologically associating domains (TADs). RB shows extensive colocalization with cohesin in the human genome, and it impacts cohesin's distribution on chromatin. Active RB evicted cohesin from RB-bound TAD boundaries, repressed insulator activity, and enhanced the expression of non-E2F target genes that are important for cell adhesion. We conclude that RB has a central role in the interplay between cell cycle and chromatin organization. This role safeguards chromatin architecture and controls transcription.