Evaluation of the dystrophin carboxy-terminal domain for micro-dystrophin gene therapy in cardiac and skeletal muscles in the DMDmdx rat model

Abstract

Duchenne muscular dystrophy (DMD) is a muscle wasting disorder caused by mutations in the gene encoding dystrophin. Gene therapy using micro-dystrophin (MD) transgenes and recombinant adenoassociated virus (rAAV) vectors hold great promise. To overcome the limited packaging capacity of rAAV vectors, most MD do not include dystrophin carboxy-terminal (CT) domain. Yet, the CT domain is known to recruit α1-and β1-syntrophins and α-dystrobrevin, a part of the dystrophin-associated protein complex (DAPC), which is a signaling and structural mediator of muscle cells. In this study, we explored the impact of inclusion of the dystrophin CT domain on ∆R4-23/∆CT MD (MD1), in DMD mdx rats, which allows for relevant evaluations at muscular and cardiac levels. We showed by LC-MS/MS that MD1 expression is sufficient to restore the interactions at a physiological level of most DAPC partners in skeletal and cardiac muscles, and that inclusion of the CT domain increases the recruitment of some DAPC partners at supra-physiological levels. In parallel, we demonstrated that inclusion of the CT domain does not improve MD1 therapeutic efficacy on DMD muscle and cardiac pathologies. Our work highlights new evidences of the therapeutic potential of MD1 and strengthens the relevance of this candidate for gene therapy of DMD.

Dystrophin deficiency impairs cell junction formation during embryonic myogenesis from pluripotent stem cells

“…The protein samples used as positive controls in the dystrophin western-blot were obtained from rat pectoral muscle biopsies from a previous study. 73 Dmd mdx rats and healthy controls were handled and housed in the UTE IRS2 from Nantes Université, according to a protocol approved by the Institutional Animal Care and Use Committee of the Région des Pays de la Loire (University of Angers, France) as well as the French Ministry for National Education, Higher Education and Research (authorization #2018102616384887).…”

Dystrophin deficiency impairs cell junction formation during embryonic myogenesis

“…Rat Muscle biopsies: The protein samples used as positive controls in the dystrophin western-blot were obtained from rat pectoral muscle biopsies from a previous study 58 . Dmd mdx rats and healthy controls were handled and housed in the UTE IRS2 from Nantes Université, according to a protocol approved by the Institutional Animal Care and Use Committee of the Région des Pays de la Loire (University of Angers, France) as well as the French Ministry for National Education, Higher Education and Research (authorization #2018102616384887).…”

Therapeutic Strategies for Dystrophin Replacement in Duchenne Muscular Dystrophy

“…The authors also indicated that the expression of micro-dystrophin in mdx 5cv mice prevented the development of cardiac histopathology but did not rescue membrane localization of cavins nor did it normalize ERK signaling ( 93 ). Bourdon et al ( 94 ) recently showed in DMD mdx rats that the ΔR4-23/ΔCT expression is sufficient to restore the interactions of most dystrophin associated protein complex (DAPC) partners in skeletal and cardiac muscles. In contrast, the addition of C terminal domain significantly increases the restoration of that interaction.…”