HIT-Cas9: A CRISPR/Cas9 Genome-Editing Device under Tight and Effective Drug Control

The CRISPR/Cas9 enabled efficient gene editing in an easy and programmable manner. Controlling its activity in greater precision is desired for biomedical research and potential therapeutic translation. Here, we engrafted the CRISPR/Cas9 system with a mutated human estrogen receptor (ER^T2), which renders it 4-hydroxytamoxifen (4-OHT) inducible for the access of genome, and a nuclear export signal (NES), which lowers the background activity. Tight and efficient drug-inducible genome editing was achieved across several human cell types, including embryonic stem cells (ESCs) and mesenchymal stem cells (MSCs), upon vigorous optimization. Optimized terminal device, which we named hybrid drug inducible CRISPR/Cas9 technology (HIT-Cas9), delivered advantageous performances over several existing designs. Such architecture was also successfully applied to an orthogonal Cas9. The HIT-Cas9 system developed in this study will find broad utility in controlled editing of potentially any genomic loci.