Developmentally regulated higher-order chromatin interactions orchestrate B cell fate commitment.

Genome organization in 3D nuclear-space is important for regulation of gene expression. However, the alterations of chromatin architecture that impinge on the B cell-fate choice of multi-potent progenitors are still unclear. By integrating in situ Hi-C analyses with epigenetic landscapes and genome-wide expression profiles, we tracked the changes in genome architecture as the cells transit from a progenitor to a committed state. We identified the genomic loci that undergo developmental switch between A and B compartments during B-cell fate determination. Furthermore, although, topologically associating domains (TADs) are stable, a significant number of TADs display structural alterations that are associated with changes in cis-regulatory interaction landscape. Finally, we demonstrate the potential roles for Ebf1 and its downstream factor, Pax5, in chromatin reorganization and transcription regulation. Collectively, our studies provide a general paradigm of the dynamic relationship between chromatin reorganization and lineage-specific gene expression pattern that dictates cell-fate determination.