Peptide nucleic acids are potent modulators of endogenous pre-mRNA splicing of the murine interleukin-5 receptor-alpha chain

Antisense oligonucleotides (ASOs) that bind target pre-mRNA with high affin ity have been shown to alter splicing patterns and offer promise as therape utics. Previous studies have shown that ASOs fully modified with 2'-O-metho xyethyl (2'-O-MOE) sugar residues redirect constitutive and alternative spl icing of the murine interleukin-5 receptor-alpha (IL-5R alpha) chain pre-mR NA in cells, resulting in inhibition of the membrane-bound isoform and enha nced expression of the soluble isoform. Here. we show that antisense peptid e nucleic acids (PNA5) alter splicing of the IL-5R alpha pre-mRNA in a fash ion similar to their 2'-O-MOE-modified counterparts of the same sequence. M oreover, using PNA as the splicing modulator, the length of the antisense o ligomer could be shortened from 20 to 15 nucleobase units to obtain a compa rable effect. Treatment of cells with antisense PNA resulted in dose-depend ent, specific downregulation of IL-5R alpha membrane isoform mRNA expressio n and enhanced levels of the soluble IL-5R alpha isoform transcript, with a n EC50 equivalent to that observed in parallel with the corresponding 2'-O- MOE ASO. The pronounced activity of antisense PNAs in modulating IL-5R alph a mRNA splicing observed in our study identifies these compounds as a promi sing new class of lower molecular weight splicing modulators.