The CRISPR journalSep 28, 2026

PARP1 may limit insertion-based prime editing depending on the DNA context

CRISPR Gene Editing Weekly Brief ↗PubMed ↗DOI ↗

Updated Sep 29, 2026

Abstract

PARP inhibitors enhanced prime editing-mediated insertions at the HEK3 locus by more than 2-fold.

Prime editing allows precise modifications to DNA but has variable efficiency.
A screen of 569 compounds revealed that PARP inhibitors specifically improve insertion efficiency.
The increase in insertion efficiency was not observed for substitution or deletion edits.
Loss of PARP1 genetically replicated the enhanced insertion phenotype, indicating its key role.
The effect of PARP1 inhibition on insertion efficiency varied by genomic location and template configuration.

Simplified

Prime editing (PE) enables precise insertions, deletions, and substitutions without double-strand breaks, but editing efficiency remains highly variable. To identify modulators of PE outcomes, we screened 569 compounds targeting DNA damage and repair pathways in K562 cells using targeted next-generation sequencing. PARP inhibitors selectively enhanced PE-mediated insertions at the HEK3 locus by more than 2-fold, without improving substitution or deletion editing. Genetic loss of PARP1 reproduced this phenotype, identifying PARP1 as the principal mediator. PARP1 inhibition enhanced insertion efficiency across multiple PE architectures, insertion sizes, and cellular backgrounds, including primary human T cells, and promoted more complete incorporation of pegRNA-encoded sequence changes without increasing indels or scaffold incorporation. However, this effect was dependent on genomic locus and reverse transcription template configuration. Together, these findings identify PARP1 as a context-dependent constraint on insertional PE.