Inhibition ofDUX4expression with antisense LNA gapmers as a therapy for facioscapulohumeral muscular dystrophy
Facioscapulohumeral muscular dystrophy (FSHD), characterized by progressive muscle weakness and deterioration, is genetically linked to aberrant expression ofDUX4in muscle. DUX4, in its full-length form, is cytotoxic in nongermline tissues. Here, we designed locked nucleic acid (LNA) gapmer antisense oligonucleotides (AOs) to knock downDUX4in immortalized FSHD myoblasts and theFLExDUX4FSHD mouse model. Using a screening method capable of reliably evaluating the knockdown efficiency of LNA gapmers against endogenousDUX4messenger RNA in vitro, we demonstrate that several designed LNA gapmers selectively and effectively reducedDUX4expression with nearly complete knockdown. We also found potential functional benefits of AOs on muscle fusion and structure in vitro. Finally, we show that one of the LNA gapmers was taken up and induced effective silencing ofDUX4upon local treatment in vivo. The LNA gapmers developed here will help facilitate the development of FSHD therapies.