High-Throughput Screening to Identify Novel Compounds Affecting the Genome Editing Efficiency of CRISPR System.

Genome editing is a promising therapeutic strategy for genetic disorders by modifying the genome precisely, especially the CRISPR/Cas9 system. However, a major limitation of CRISPR/Cas9 in gene therapy is the biosafety issues caused by off-target effects. Compounds that can modulate the genome editing efficiency of the CRISPR/Cas9 system, especially those reducing the off-target effects, are potentially useful pharmacological tools for improving the effectiveness and safety of genome editing. Here, we performed high-throughput screening in HEK 293FT cells to discover compounds that decrease or increase the genome editing efficiency of the CRISPR/Cas9 system from 9930 compounds. After two rounds of screening, we identified that CP-724714, a ErbB2 (HER2) tyrosine kinase inhibitor, decreased the CRISPR/Cas9 efficiency and reduced the off-target effects by suppressing the efficiency of CRISPR/Cas9, and was thus named a CRISPR decelerator (or inhibitor), while Clofarabine, a DNA synthesis inhibitor, increased the efficiency of CRISPR/Cas9, and was named a CRISPR accelerator. We further identified four compounds (Tranilast, Cerulenin, Rosolic acid and Resveratrol) that affected the efficiency of single-strand annealing (SSA) repair. Among them, Tranilast, Cerulenin and Rosolic acid are potential SSA decelerators, while Resveratrol is a potential SSA accelerator. These identified compounds may be useful in optimizing mammalian genetic manipulation techniques.