Dystrophin threshold level necessary for normalisation of nNOS, iNOS and RyR1 nitrosylation in GRMD dystrophinopathy - Sorbonne Université Access content directly
Journal Articles Human Gene Therapy Year : 2016

Dystrophin threshold level necessary for normalisation of nNOS, iNOS and RyR1 nitrosylation in GRMD dystrophinopathy

Abstract

Currently, the clinically most advanced strategy to treat Duchenne muscular dystrophy (DMD) is the exon skipping strategy. Whereas antisense oligonucleotide-based clinical trials are underway for DMD, it is essential to determine a dystrophin restoration threshold needed to ensure improvement of muscle physiology at the molecular level. A preclinical trial was recently conducted in golden retriever muscular dystrophy (GRMD) dogs treated in a forelimb by locoregional delivery of rAAV8-U7snRNA to promote exon skipping on the canine dystrophin messenger. Here, we exploited the rAAV8-U7snRNA transduced GRMD muscle samples, well-characterized for their percentage of dystrophin-positive fibers, in the aim to define a threshold of dystrophin rescue necessary for normalization of the status of the neuronal nitric oxide synthase mu (nNOSµ), the inducible nitric oxide synthase (iNOS), and the ryanodine receptor-calcium release channel type 1 (RyR1), crucial actors for an efficient contractile function. Results showed that the restoration of dystrophin in 40% of muscle fibers is needed to decrease the abnormal cytosolic nNOSµ expression and to reduce the overexpression of iNOS, these two parameters leading to a reduction of the NO level into the muscle fiber. Furthermore, the same percentage of dystrophin-positive fibers of 40 % was associated with the normalization of the RyR1 nitrosylation status and to a stabilization of the RyR1/calstabin1 complex that is required to facilitate coupled gating. We concluded that a minimal threshold of 40% of dystrophin-positive fibers is necessary for the reinstatement of central proteins needed for a proper muscle contractile function, and thus identified a rate of dystrophin expression significantly improving, at the molecular level, the dystrophic muscle physiology.
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Dates and versions

hal-01340106 , version 1 (30-06-2016)

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Christel Gentil, Caroline Le Guiner, Sestina Falcone, Jean-Yves Hogrel, Cecile Peccate, et al.. Dystrophin threshold level necessary for normalisation of nNOS, iNOS and RyR1 nitrosylation in GRMD dystrophinopathy. Human Gene Therapy, 2016, 27 (9), pp.712-726. ⟨10.1089/hum.2016.041⟩. ⟨hal-01340106⟩
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