Enrichment of prime-edited mammalian cells with surrogate PuroR reporters

Abstract

Prime editing is a programmable genetic method that can precisely generate any desired small-scale variations in cells without requiring double-strand breaks and DNA donors. However, higher editing efficiency is greatly desirable for wide practical applications. In this study, we developed a target-specific prime editing reporter (tsPER) and a universal prime editing reporter (UPER) to facilitate rapid selection of desired edited cells through puromycin screening. The modification efficiency of HEK3_i1CTT_d5G in HEK293T cells improved from 36.37 % to 64.84 % with the incorporation of tsPER. The target sequence of interested genes could be custom inserted into a selection cassette in tsPER to establish personalized reporters. The UPER demonstrated PE3 editing efficiency up to 74.49 % on HEK3_i1CTT_d5G and 73.52 % on HEK3_i1His6, achieved through co-selection with an additional pegRNA (puro) to repair the mutant PuroR cassette. Overall, tsPER and UPER robustly improved the efficiency of prime editing. Both of these approaches expand enrichment strategies for genomically modified cells and accelerate the generation of genetically modified models.