Long-range chromatin interactions play critical roles in genome organization and 
regulation of transcription. We now report transposase-mediated analysis of 
chromatin looping (Trac-looping) for simultaneous detection of multiscale 
genome-wide chromatin interactions among regulatory elements and chromatin 
accessibility. With this technique, a bivalent oligonucleotide linker is 
inserted between two interacting regions such that the chromatin interactions 
are captured without prior chromatin fragmentation and proximity-based ligation. 
Application of Trac-looping to human CD4+ T cells revealed substantial 
reorganization of enhancer-promoter interactions associated with changes in gene 
expression after T cell receptor stimulation.