AAV-mediated gene transfer restores a normal muscle transcriptome in a canine model of X-linked myotubular myopathy

Abstract Multiple clinical trials employing recombinant adeno-associated viral (rAAV) vectors have been initiated for neuromuscular disorders, including Duchenne and limb-girdle muscular dystrophies, spinal muscular atrophy, and recently X-linked myotubular myopathy (XLMTM). Our previous work on a canine model of XLMTM showed that a single rAAV8-cMTM1 systemic infusion corrected structural abnormalities within the muscle and restored contractile function, with affected dogs surviving more than four years post injection. This remarkable therapeutic efficacy presents a unique opportunity to identify the downstream molecular drivers of XLMTM pathology, and to what extent the whole muscle transcriptome is restored to normal after gene transfer. Herein, RNA-sequencing was used to examine the transcriptomes of the Biceps femoris and Vastus lateralis in a previously-described canine cohort that showed dose-dependent clinical improvements after rAAV8-cMTM1 gene transfer. Our analysis confirmed several dysregulated genes previously observed in XLMTM mice, but also identified transcripts linked to XLMTM pathology. We demonstrated XLMTM transcriptome remodeling and dose-dependent normalization of gene expression after gene transfer and created metrics to pinpoint potential biomarkers of disease progression and correction.