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

面肩肱型肌营养不良症 (FSHD) 的特点是进行性肌肉无力和恶化，与肌肉中DUX4的异常表达存在遗传相关性。全长形式的 DUX4 在非种系组织中具有细胞毒性。在这里，我们设计了锁核酸（LNA）gapmer反义寡核苷酸（AO）来敲低永生化FSHD成肌细胞和FLExDUX4 FSHD小鼠模型中的DUX4。使用能够在体外可靠地评估LNA间隙体对内源性DUX4信使RNA的敲低效率的筛选方法，我们证明了几种设计的LNA间隙体选择性地、有效地降低了DUX4表达，并且几乎完全敲低。我们还发现 AO 对体外肌肉融合和结构的潜在功能益处。最后，我们表明，在体内局部处理后，其中一种 LNA 缺口聚体被吸收并诱导DUX4的有效沉默。这里开发的 LNA gapmers 将有助于促进 FSHD 疗法的开发。