Preferential correction of target genes by 5'-tailed duplexes with an antisense editor strand

The correction (editing) of mutated genes at the DNA level is expected to cure gene-inherited diseases and cancers. A 5'-tailed duplex (TD) with an approximately 80-base editor strand (E-strand) plus a 35-base assistant strand (A-strand) was developed for gene editing without artificial nucleases. The E-strand has the normal (or desired) sequence and the A-strand hybridizes to the 3'-region of the E-strand. In this study, the polarity-dependency of gene editing by TDs was examined. The sense and antisense E-strands for eight transcribed target genes, including the WRN (Werner syndrome) gene, were designed, and the target plasmid DNAs were co-transfected with the TDs into human U2OS cells. Most TDs with the antisense E-strand corrected the targets more efficiently than those with the sense E-strand. However, transcription had only a slight effect on gene correction efficiency. These results suggested that the TDs containing the antisense E-strand are more useful editing tools than the sense TDs.