Inhibition of <i>DUX4</i> expression with antisense LNA gapmers as a therapy for facioscapulohumeral muscular dystrophy

Abstract

Facioscapulohumeral muscular dystrophy (FSHD), characterized by progressive muscle weakness and deterioration, is genetically linked to aberrant expression of <i>DUX4</i> in 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 down <i>DUX4</i> in immortalized FSHD myoblasts and the <i>FLExDUX4</i> FSHD mouse model. Using a screening method capable of reliably evaluating the knockdown efficiency of LNA gapmers against endogenous <i>DUX4</i> messenger RNA in vitro, we demonstrate that several designed LNA gapmers selectively and effectively reduced <i>DUX4</i> expression 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 of <i>DUX4</i> upon local treatment in vivo. The LNA gapmers developed here will help facilitate the development of FSHD therapies.