A Deoxyribonucleic Acid Decoy Trapping DUX4 for the Treatment of Facioscapulohumeral Muscular Dystrophy

Abstract

Facioscapulohumeral dystrophy (FSHD) is characterized by a loss of repressive epigenetic marks leading to the aberrant expression of the DUX4 transcription factor. In muscle, DUX4 acts as a poison protein though the induction of multiple downstream genes. So far, there is no therapeutic solution for FSHD. Because DUX4 is a transcription factor, we developed an original therapeutic approach, based on a DNA decoy trapping the DUX4 protein, preventing its binding to genomic DNA and thereby blocking the aberrant activation of DUX4's transcriptional network. In vitro, transfection of a DUX4 decoy into FSHD myotubes reduced the expression of the DUX4 network genes. In vivo, both double-stand DNA DUX4 decoys and adeno-associated viruses (AAVs) carrying DUX4 binding sites reduced transcriptional activation of genes downstream of DUX4 in a DUX4-expressing mouse model. Our study demonstrates, both in vitro and in vivo, the feasibility of the decoy strategy and opens new avenues of research.

Long-Term Systemic Treatment of a Mouse Model Displaying Chronic FSHD-like Pathology with Antisense Therapeutics That Inhibit DUX4 Expression

“…Since the aberrant expression of the double homeobox 4 ( DUX4 ) gene has been suggested as a predominant cause of FSHD pathogenesis [ 12 , 13 , 14 ], targeting DUX4 has great potential to provide a cure for the disease. Therefore, we and others have developed several approaches for suppressing DUX4 expression or its downstream activity [ 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 ]. Despite FSHD affecting multiple skeletal muscles, only a few studies describe the systemic effects of therapeutic strategies on FSHD-like animal models.…”

Downstream events initiated by expression of FSHD-associated DUX4: Studies of nucleocytoplasmic transport, γH2AX accumulation, and Bax/Bak-dependence

“…As potential therapies for FSHD, multiple groups are developing technologies to inhibit the function or expression of DUX4-FL (e.g. Bosnakovski et al, 2019 ; Bouwman et al, 2021 ; Das and Chadwick, 2021 ; Himeda et al, 2020 ; Lim et al, 2020 , 2021 ; Lu-Nguyen et al, 2021 ; Mariot et al, 2020 ; Mellion et al, 2021 ; Oliva et al, 2019 ; Rashnonejad et al, 2020 ; Šikrová et al, 2021 ). Direct targeting of DUX4 will likely be the primary therapeutic strategy for FSHD, because once begun, any technique that inhibits DUX4 expression or function should block multiple pathogenic changes that are dependent on DUX4 transcriptional activity ( Mitsuhashi et al, 2018 ).…”

FSHD Therapeutic Strategies: What Will It Take to Get to Clinic?

“…A different oligonucleotide approach utilizes DNA binding site decoys (DNA aptamers) to bind a transcription factor and block its ability to regulate target genes. Such decoys can bind recombinant DUX4-FL with high affinity [ 72 ], and others were demonstrated to block binding of DUX4 to its target genes following electroporation of DUX4 into wild-type mice [ 73 ].…”