CRISPR-Cas9 cytidine and adenosine base editing of splice-sites mediates highly-efficient disruption of proteins in primary and immortalized cells
Mitchell G. Kluesner, Walker S. Lahr, Cara-lin Lonetree, Branden A. Smeester, Xiaohong Qiu, Nicholas J. Slipek, Patricia Claudio-Vázquez, Samuel P. Pitzen, Emily J. Pomeroy, Madison J. Vignes, Samantha C. Lee, Samuel P. Bingea, Aneesha A. Andrew, Beau R. Webber, Branden S. Moriarity
Abstract
CRISPR-Cas9 cytidine and adenosine base editors (CBEs and ABEs) can disrupt genes without introducing double-stranded breaks by inactivating splice sites (BE-splice) or by introducing premature stop (pmSTOP) codons. However, no in-depth comparison of these methods or a modular tool for designing BE-splice sgRNAs exists. To address these needs, we develop SpliceR ( http://z.umn.edu/spliceR ) to design and rank BE-splice sgRNAs for any Ensembl annotated genome, and compared disruption approaches in T cells using a screen against the TCR-CD3 MHC Class I immune synapse. Among the targeted genes, we find that targeting splice-donors is the most reliable disruption method, followed by targeting splice-acceptors, and introducing pmSTOPs. Further, the CBE BE4 is more effective for disruption than the ABE ABE7.10, however this disparity is eliminated by employing ABE8e. Collectively, we demonstrate a robust method for gene disruption, accompanied by a modular design tool that is of use to basic and translational researchers alike.