Investigation of twisted intercalating nucleic acid (TINA)-modified antisense oligonucleotides for splice modulation by induced exon-skipping in vitro

Twisted intercalating nucleic acids (TINA)-modified oligonucleotides containing phenylethynylpyren-1-yl derivatives were reported to improve the thermal stability of the nucleic acid duplexes, triplexes and G-quadruplexes. In the present study, we have investigated the potential of TINA-modified antisense oligonucleotides (AOs) in splice modulation by induced exon-skipping in vitro. We used both para-TINA (p-TINA) and ortho-TINA (o-TINA)-modified 2′-O-methyl (2′-OMe) AOs on a phosphorothioate backbone (PS) designed to skip exon-23 in dystrophin pre-mRNA transcript in mdx mice myotubes. A fully-modified 2′-OMePS AO control was used in parallel. Our results showed that both p-TINA and o-TINA-modified AOs were able to induce exon-23 skipping. These results provide new insights on expanding the applicability of TINA-modified oligonucleotides