SMCHD1 Merges Chromosome Compartments and Assists Formation of Super-Structures on the Inactive X.

摘要: Summary Mammalian chromosomes are partitioned into A/B compartments and topologically associated domains (TADs). The inactive X (Xi) chromosome, however, adopts a distinct conformation without evident or TADs. Here, through exploration of an architectural protein, structural-maintenance-of-chromosomes hinge domain containing 1 (SMCHD1), we probe how the Xi is reconfigured during X chromosome inactivation. first fused "S1" "S2" compartments, coinciding with Xist spreading gene-rich domains. SMCHD1 then binds S1/S2 merges them to create compartment-less architecture. Contrary current views, TADs remain on the Xi but in attenuated state. Ablating results persistent organization and strengthening Furthermore, loss causes regional defects erosion heterochromatic silencing. We present stepwise model for folding, where attenuates a hidden layer architecture facilitate spreading.