Selective requirement of 3D genomic organization for the Mdm1-Il22-Ifng locus regulation in initial Th1 cell lineage specification and differentiation

Eukaryotic DNA fibers are organized into structured subunits in the nucleus, but the extent to which these 3D chromatin architectures influence cytokine expression remains unclear. Here, we investigate the role of dynamic loop formation within the topologically associating domain (TAD) in regulating the expression of two critical cytokines, interferon-gamma (IFN-) and interleukin-22 (IL-22). These cytokine loci are closely located in the genome and are associated with complex enhancer landscapes, which are selectively active in type 1 and type 3 lymphocytes. Using in situ Hi-C, we demonstrate inducible TADs that insulate Ifng and Il22 enhancers during Th1 differentiation. Deleting the boundary of these TADs resulted in imbalanced Th1- and Th17-associated immunity, both in vitro and in vivo. In contrast, this boundary element was dispensable for cytokine regulation in NK cells. Our finding suggest that precise cytokine regulation relies on lineage- and developmental stage-specific interactions of 3D chromatin architectures and enhancer landscapes.