A three-dimensional map of the human genome at kilobase resolution reveals principles of chromatin looping

Summary

We use in situ Hi-C to probe the three-dimensional architecture of genomes, constructing haploid and diploid maps of nine cell types. The densest, in human lymphoblastoid cells, contains 4.9 billion contacts, achieving 1-kilobase resolution. We find that genomes are partitioned into local domains, which are associated with distinct patterns of histone marks and segregate into six subcompartments. We identify ~10,000 loops. These loops frequently link promoters and enhancers, correlate with gene activation, and show conservation across cell types and species. Loop anchors typically occur at domain boundaries and bind CTCF. CTCF sites at loop anchors occur predominantly (>90%) in a convergent orientation, with the asymmetric motifs ‘facing’ one another. The inactive X-chromosome splits into two massive domains and contains large loops anchored at CTCF-binding repeats.

eToC Blurb

Loop anchors typically occur at domain boundaries and bind CTCF in a convergent orientation, with the asymmetric motifs ‘facing’ one another. On the inactive X-chromosome, large imprinted loops are anchored at CTCF-binding repeats. Loops are conserved across cell types and species.