Ultrafine Mapping of Chromosome Conformation at hundred basepair resolution reveals regulatory genome architecture

The resolution limit of chromatin conformation capture methodologies (3Cs) has restrained their application in detection of fine-level chromatin structure mediated by cis-regulatory elements (CREs). Here we report two 3C-derived methods, Tri-4C and Tri-HiC, utilizing mult-restriction enzyme digestions capable of achieveing ultrafine genome digestion for targeted and global chromatin interaction mapping, respectively, at a one hundred basepair resolution. Tri-4C identified loops associated with CREs including those involving regulatory elements devoid of typical epigenomic marks, quantifatively revealing alterations in interaction networks underlying dynamic gene control. Tri-HiC successfully uncovers fine-gage enhancer:promoter (E:P) loops at genome-wide level, identifying > 20-fold more CRE loops than in situ HiC. In addition to refined loop detection, Tri-HiC also reveals interaction stripes and contact domain insulation from promoters and enhancers, revealing their loop extrusion behaviors resembling the topologically-associated domain (TAD) boundaries. Tri-4C and Tri-HiC provide robust approaches to achieve the high resolution interactome maps required for characterizing fine-gage regulatory chromatin interactions in analysis of development, homeostasis and disease. High resolution mapping of global long range chromatin interaction in IMR90 cells