Intracellular Membrane Repair Dysregulation and Accumulation of Mature Myostatin Protein are Novel Markers of Muscle Pathophysiology in Pompe Disease

Pompe disease is an autosomal recessive metabolic disorder caused by acid alpha-glucosidase deficiency, characterized by progressive skeletal muscle weakness and respiratory insufficiency. Affected muscles exhibit glycogen-filled lysosomes, autophagic build-up, and mitochondrial abnormalities. Despite global myofibrillar disorganization, satellite cells (SCs) fail to activate, due to mechanisms that remain unclear. This study sought to comprehensively characterize the phenotypic features of affected muscles in Pompe disease, focusing in particular on membrane repair processes, as membrane damage is a primary trigger for SC activation. Longitudinal transcriptomic analysis of muscle from a Pompe disease mouse model, combined with immunohistochemical and biochemical analyses, showed early and sustained overexpression of dysferlin (DYSF), annexin A2 (ANXA2), and AHNAK2, proteins involved in membrane repair. Abnormal localization of these proteins was observed throughout the disease course, as evidenced by sarcoplasmic accumulation at lysosomes, autophagosomes, and T-tubules, respectively. These alterations suggest a compensatory mechanism to preserve the integrity of intracellular structures. Analysis of muscle biopsies from patients with late-onset Pompe disease (LOPD) suggested sarcoplasmic localization of DYSF, ANXA2 and AHNAK2 that correlated with the severity of the histological phenotype. Moreover, in the mouse model, we observed persistent post-transcriptional accumulation of mature myostatin, a key negative regulator of muscle growth, which may contribute to impaired SC activation and the absence of muscle regeneration despite extensive tissue damage. In conclusion, our findings identified differential expression of proteins associated with intracellular membrane repair and dysregulation of myostatin as key markers in the course of Pompe disease. These insights provide new perspectives on the underlying pathophysiology and point to novel therapeutic avenues for limiting disease-associated damage.