Chimeric oligonucleotides combining guide RNA and single-stranded DNA repair template effectively induce precision gene editing.

ABSTRACT

The ability to precisely alter the genome holds immense potential for molecular biology, medicine and biotechnology. The development of the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) into a genomic editing tool has vastly simplified genome engineering. Here, we explored the use of chemically synthesized chimeric oligonucleotides encoding a target-specific crRNA (CRISPR RNA) fused to a single-stranded DNA repair template for RNP-mediated precision genome editing. By generating three clinically relevant oncogenic driver mutations, two non-stop extension mutations, an FGFRi resistance mutation and a single nucleotide change, we demonstrate the ability of chimeric oligos to form RNPs and direct Cas9 to effectively induce genome editing. Further, we demonstrate that the polarity of the chimeric oligos is crucial only chimeric oligos with the single-stranded DNA repair template fused to the 3'-end of the crRNA are functional for accurate editing, while templates fused to the 5'-end are ineffective. We also find that chimeras can perform editing with both symmetric and asymmetric single-stranded DNA repair templates. Depending on the target locus, the editing efficiency using chimeric RNPs is similar to or less than the efficiency of editing using the bipartite standard RNPs. Our results indicate that chimeric RNPs comprising RNA-DNA oligos formed from fusing the crRNA and DNA repair templates can successfully induce precise edits. While chimeric RNPs do not display an advantage over standard RNPs, they nonetheless represent a viable approach for one-molecule precision genome editing.