A multiscale 3D chromatin architecture that controls development of the humoral immune system is assembled by IKAROS [HiChIP_LpreB_Inducible]

ABSTRACT: A generic level of chromatin organization generated by the interplay between cohesin and CTCF suffices to limit promiscuous interactions between regulatory elements, but a lineage-specific assembly of chromatin that supercedes these constraints is required to configure the genome to support the gene expression changes that guide faithful lineage progression. Using loss-of-function approaches in B cell precursors in vivo we show that IKAROS assembles interactions between sites often separated by megabase distances to configure a significant fraction of the genome in preparation for lymphoid development. Interactions emanating from IKAROS-bound enhancers override CTCF-imposed boundaries and assemble lineage-specific regulatory units built on a backbone of smaller invariant topological domains.In vitro deletion provides temporal resolution to changes in chromatin modifications, loops, and compartmental localization. Gain-of-function experiments in epithelial cells confirm IKAROS’ ability to reconfigure chromatin architecture at multiple scales. While the compaction of the Igk locus required for genome editing represents a function of IKAROS unique to the lymphoid system, the more general function of this lineage-defining DNA binding protein to preconfigure the genome to support lineage specific gene expression and suppress activation of extra-lineage genes provides a paradigm for lineage restriction.

ORGANISM(S): Mus musculus

PROVIDER: GSE231880 | GEO | 2023/11/20

REPOSITORIES: GEO