Increase genome editing efficiency by Cas9 transcriptional activator and histone acetyltransferase activator

The CRISPR/Cas9 system shows diverse levels of genome editing activities on eukaryotic genomic DNA targets, and experiments desire high-efficiency targets. Here we show that chromatin open status is a pivotal determinant of the Cas9 editing activity in mammalian cells, and increasing chromatin accessibility can efficiently improve Cas9 genome editing activity. However, the strategy that fusing the VP64 transcriptional activation domain at the C-terminus of Cas9 can only promote genome editing activity slightly at most tested CRISPR/Cas9 targets in Lenti-X 293T cells. Because histone acetylation increases eukaryotic chromatin accessibility, we further improve genome editing by elevating histone acetylation. We demonstrate that promoting histone acetylation using histone acetyltransferase (HAT) activator YF-2 can improve genome editing from Cas9 and more robustly from the Cas9 transcriptional activator. This provides a strategy to improve CRISPR/Cas9 genome editing activity and enables broader gRNA target choices in eukaryotes. Overall design: Qilai Huang