Antisense Oligonucleotides Used to Target the DUX4 mRNA as Therapeutic Approaches in FaciosScapuloHumeral Muscular Dystrophy (FSHD)

Abstract

FacioScapuloHumeral muscular Dystrophy (FSHD) is one of the most prevalent hereditary myopathies and is generally characterized by progressive muscle atrophy affecting the face, scapular fixators; upper arms and distal lower legs. The FSHD locus maps to a macrosatellite D4Z4 repeat array on chromosome 4q35. Each D4Z4 unit contains a DUX4 gene; the most distal of which is flanked by a polyadenylation site on FSHD-permissive alleles, which allows for production of stable DUX4 mRNAs. In addition, an open chromatin structure is required for DUX4 gene transcription. FSHD thus results from a gain of function of the toxic DUX4 protein that normally is only expressed in germ line and stem cells. Therapeutic strategies are emerging that aim to decrease DUX4 expression or toxicity in FSHD muscle cells. We review here the heterogeneity of DUX4 mRNAs observed in muscle and stem cells; and the use of antisense oligonucleotides (AOs) targeting the DUX4 mRNA to interfere either with transcript cleavage/polyadenylation or intron splicing. We show in primary cultures that DUX4-targeted AOs suppress the atrophic FSHD myotube phenotype; but do not improve the disorganized FSHD myotube phenotype which could be caused by DUX4c over-expression. Thus; DUX4c might constitute another therapeutic target in FSHD.

Diverse lipid conjugates for functional extra-hepatic siRNA deliveryin vivo

“…Though the chol-siRNA targeting sFLT1 is efficiently delivered to placenta (~8% of injected dose), it also accumulates to liver and kidneys where silencing of sFLT1 is believed to be tolerated and irrelevant for disease progression. There are targets of the similar nature, including DUX4 in muscular dystrophy 47 .…”

Transgenic mice expressing tunable levels of DUX4 develop characteristic facioscapulohumeral muscular dystrophy-like pathophysiology ranging in severity

“…1a). Importantly, since many elements within DUX4 are prime targets for sequence-based therapies [49][50][51][52], the DUX4 transgene maintains the exon/intron structure of the endogenous human gene, including the 5′ untranslated region (UTR), the endogenous PAS, and the distal auxiliary elements (DAEs) that enhance DUX4 mRNA cleavage and polyadenylation events [5,9,[52][53][54]. Here, we show that the FLExD mouse model, when crossed with the skeletal muscle-specific and tamoxifen (TMX)-inducible ACTA1-Mer-cre-Mer mouse [55], produces a bi-transgenic model with chronic low levels of mosaic DUX4-fl expression in skeletal muscle and reproducibly recapitulating many aspects of FSHD pathophysiology.…”

Préclinique

“…L'étiologie de la DMFSH a longtemps été mysté-rieuse, mais la confirmation récente de l'implication de DUX4 le désigne donc comme une cible de choix. Une équipe a décrit une approche très semblable à celle-ci in vitro, aboutissant au choix de séquences similaires [2], et une autre encore a démontré in vitro des bénéfices partiels liés à l'utilisation de certains oligonucléotides [3]. Ces résultats soulignent la pertinence de cette stratégie.…”