Systematic mapping of enhancers, silencers, and topological elements with prime editing deletion screens
Swap-seq, a method combining pooled twin prime editing with flow-sorting, deletes hundreds of endogenous regulatory sequences and measures their quantitative effects on nearby gene expression. Applied to PPIF regulation in THP-1 monocytes, it quantifies distal and intronic enhancers, characterizes CTCF insulators, and uncovers a silencer that represses neighboring enhancers through HDAC-mediated mechanisms, with hundreds of genomic elements sharing its signatures. The resulting data show sequence-to-function models capture local element activity but fail to link elements to distal target genes.
Why it matters: It delivers a generalizable deletion-screening tool and a benchmark showing sequence-to-function models miss distal gene targeting.
