DUX4 Expression in FSHD Muscles: Focus on Its mRNA Regulation

Charpentier

et al. 2020

JPM

Self Cite

Facioscapulohumeral dystrophy (FSHD, OMIM: 158900, 158901) is the most common dystrophy in adults and so far, there is no treatment. Different loci of the disease have been characterized and they all lead to the aberrant expression of the DUX4 protein, which impairs the function of the muscle, ultimately leading to cell death. Here, we used gene editing to try to permanently shut down DUX4 expression by targeting its poly(A) sequence. We used transcription activator-like effector nucleases (TALEN) and CRISPR-Cas9 nucleases in vitro on FSHD myoblasts. More than 150 TOPO clones were sequenced and only indels were observed in 4%. Importantly, in 2 of them, the DUX4 poly(A) signal was eliminated at the genomic level but DUX4 mRNA was still produced thanks to the use of a non-canonical upstream poly(A) signal sequence. These experiments show that targeting DUX4 PAS at the genomic level might not be an appropriate gene editing strategy for FSHD therapy.

Section: Introductionmentioning

confidence: 99%

Gene Editing Targeting the DUX4 Polyadenylation Signal: A Therapy for FSHD?

Joubert

Charpentier

et al. 2020

JPM

Self Cite

“…• Blocking the activity of the DUX4 protein DUX4 is a double homeobox retrogene and 3 main DUX4 isoforms have been characterized (for review see [13]). Two lead to the full length protein (DUX4-fl) that is a toxic transcription factor, whereas the third one leads to a non-pathogenic protein (DUX4-s).…”

Section: Downstream Approach: Targeting Dux4-fl Protein Toxicitymentioning

confidence: 99%

“…Studies have demonstrated that DUX4 mRNAs undergo alternate splicing in muscle [10,12]: Three DUX4 isoforms are mainly produced, a truncated DUX4 known as DUX4-s, and two full length DUX4 transcripts, DUX4-fl. DUX4-fl transcripts code the full length DUX4 protein, whereas DUX4-s codes a truncated and inactive version of DUX4 and therefore DUX4-fl transcripts are the only transcript associated with FSHD pathology (for review see [13]). Indeed, DUX4 is a toxic transcription factor, activating hundreds of downstream genes, impairing muscle development, activating the immune response, increasing susceptibility to oxidative stress, ultimately leading to the activation of cell death pathways (for review see [14]).…”

Section: Introductionmentioning

confidence: 99%

Therapeutic Strategies Targeting DUX4 in FSHD

Gall

Sidlauskaite

et al. 2020

JCM

Self Cite

Facioscapulohumeral muscular dystrophy (FSHD) is a common muscle dystrophy typically affecting patients within their second decade. Patients initially exhibit asymmetric facial and humeral muscle damage, followed by lower body muscle involvement. FSHD is associated with a derepression of DUX4 gene encoded by the D4Z4 macrosatellite located on the subtelomeric part of chromosome 4. DUX4 is a highly regulated transcription factor and its expression in skeletal muscle contributes to multiple cellular toxicities and pathologies ultimately leading to muscle weakness and atrophy. Since the discovery of the FSHD candidate gene DUX4, many cell and animal models have been designed for therapeutic approaches and clinical trials. Today there is no treatment available for FSHD patients and therapeutic strategies targeting DUX4 toxicity in skeletal muscle are being actively investigated. In this review, we will discuss different research areas that are currently being considered to alter DUX4 expression and toxicity in muscle tissue and the cell and animal models designed to date.

“…1,6 DUX4 expression is extremely low but it has been robustly found in adult and fetal FSHD muscle cells and biopsies. 3,[7][8][9] DUX4 might be the major trigger of FSHD onset/progression by disrupting several cellular pathways and inducing cell death in different models (for review see DeSimone et al 10 ). Several laboratories, including ours, have developed therapeutic strategies based on DUX4 silencing mediated by RNA interference, antisense oligonucleotides (AONs), artificial miRNAs, the short-spliced form of DUX4 (DUX4 s), or drugs.…”

Section: Introductionmentioning

confidence: 99%

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

Molecular Therapy - Nucleic Acids

Joubert

Marsollier

et al. 2020

Self Cite

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.