Engineering a Far-Red Light-Controlled Split-Cas9 Device for Genome Editing in Human Cells and Mice

The CRISPR-Cas9 technology has emerged as a powerful tool for targeted genome editing. However, uncontrollable expression of Cas9 greatly increases side effects due to the off-target cleavage. In order to address this problem and achieve conditional genome editing, several chemical inducible Cas9 systems have been developed. In this work, we demonstrated a far-red light-controlled split-Cas9 (FRL-Cas9) device that enables spatiotemporal control of genome editing in human cells and in a tdTomato reporter mouse model. In the meanwhile, we also showed that this FRL-Cas9 device could also be used to knock out oncogenes in tumor-bearing mouse model for cancer therapy simply by illumination. This optogenetically controlled device demonstrated a robust genome editing performance that exhibits remarkable reversibility, non-invasibility, negligible phototoxicity and deep tissue penetration for in vivo applications. This FRL-Cas9 device enables optogenetic control of targeted genome editing, which facilities better understanding of complex gene networks in basic biological research. Moreover, this optogenetic device opens new opportunities for dynamic and spatiotemporal interventions in gene-based precision medicine.