Ectopic recruitment of the CTCF N-terminal domain with two proximal zinc-finger domains as a tool for 3D genome engineering [Hi-C]

We developed a panel of chimeric proteins consisting of either full-length or truncated CTCF fused with programmable DNA-binding module dCas9 and fluorescent tracker EGFP. We found that the recruitment of a chimeric protein based on the CTCF N-­terminal domain and two zinc-finger domains to the human HOXD locus leads to the de novo formation of a spatial contact with a nearby cohesin/CTCF-­bound region anchoring several chromatin loops. This chimeric protein did not show binding to CTCF motifs and did not affect epigenetic and transcription profile of the locus. Recruitment of this chimeric protein is also able to restore chromatin loops, lost after deletion of an endogenous CTCF ­binding site. Together, our data indicate that the ectopic recruitment of CTCF N-terminal part could be an appropriate tool for the 3D genome engineering. Overall design: ChIP-seq and HiC-seq in K562 cells with full or truncated CTCF.