Activating frataxin expression by single-stranded siRNAs targeting the GAA repeat expansion

Xiulong Shen, Audrius Kilikevicius, Daniel O'Reilly, Thazha P. Prakash, Masad J. Damha, Frank Rigo, David R. Corey, Bioorganic & Medicinal Chemistry Letters 2018, doi:10.1016/j.bmcl.2018.07.033.

Agents that increase expression of FXN protein are a potential approach to therapy. We previously described anti-trinucleotide GAA duplex RNAs (dsRNAs) and antisense oligonucleotides (ASOs) that activate FXN protein expression in multiple patient derived cell lines. Here we test two distinct series of compounds for their ability to increase FXN expression. ASOs with butane linkers showed low potency, which is consistent with the low Tm values and suggesting that flexible conformation impairs activity. By contrast, single-stranded siRNAs (ss-siRNAs) that combine the strengths of dsRNA and ASO approaches had nanomolar potencies. ss-siRNAs provide an additional option for developing nucleic acid therapeutics to treat FRDA.

 Activating frataxin expression by single-stranded siRNAs targeting the GAA repeat expansion