Figure 1.
Drug screening with the HAP1-ABEdox:GFP reporter system. (A) Schematic overview of the doxycycline (Dox)-dependent HAP1-ABEdox:GFP reporter system. The EGFP-targeting gRNA was expressed by the U6 promoter, and EGFP with a premature stop codon (TAG) in the third amino acid position was expressed by the CMV promoter. The two cassettes, U6-gRNA and CMV-EGFP, were arranged in opposite orientations. The ABE7.10 expression was controlled by doxycycline and converted the premature stop codon into glutamine for EGFP expression. (B) The relative fold-change of GFP expression levels in 414 anti-cancer drug screens with a concentration of 100 nM. The fold-changes resulting from each drug were calculated relative to the GFP expression levels in cells treated with doxycycline alone. Four HDAC inhibitors are indicated (raw numbers are provided in Supplementary Table S3). All agents were assessed using biological duplicates. (C) The adenine base editing efficiencies at the EGFP target site were analyzed using targeted deep sequencing. The A:T to G:C substitution frequency at the A6 position was 72.9% in 10 nM romidepsin-treated cells as compared to 37.9% in cells treated with doxycycline alone.