Ultrafine Mapping of Chromosome Conformation at hundred basepair resolution reveals regulatory genome architecture. 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. Overall design: High resolution mapping of global long range chromatin interaction in IMR90 cells