This dysferlin-deficient cell line should allow the study of pathophysiological pathways involved in dysferlin-deficient muscle and constitute a tool for high-throughput screening of therapeutic compounds for patients with dysferlinopathy and other muscle diseases.
Altered immunolocalization of dysferlin was observed in not only primary dysferlinopathy, but also in the several diseased muscles with normal protein contents.
The homozygous or compound heterozygous mutation of the alleles of DYSF gene causes dysferlinopathy resulting in limb girdle muscular dystrophy Type 2B (LGMD 2B) or Miyoshi myopathy.
Three different novel, homozygous mutations in CAPN1 were found: c.2118+1G > T, c.397C > T, c.843+1G > C. The patient with the earliest onset also manifested profound muscle weakness, likely related to a second homozygous mutation in DYSF (dysferlinopathy).
Our results provide the mechanism for dysferlin-mediated repair of skeletal muscle sarcolemma and identify ASM as a potential therapy for dysferlinopathy.
The diagnosis of dysferlinopathy was based on the absence or strong reduction of dysferlin in muscle, and confirmed by mutational screening of the DYSF gene.
Although muscle inflammation is widely recognized in dysferlinopathy and dysferlin is expressed in immune cells, the contribution of the immune system to the pathology of dysferlinopathy remains to be fully explored.
These preclinical data are the first report of a smaller dysferlin variant tailored for AAV single particle delivery that restores motor function and, therefore, represents an attractive candidate for the treatment of dysferlinopathy.
We introduce accelerated endosomal-directed degradation as a basis for lability of dysferlin missense mutants in dysferlinopathy, and show that dysferlin and syntaxin-4 similarly transit a common endosomal pathway in skeletal muscle cells.
Dysferlin is known to play an essential role in skeletal muscle fibre repair, but the process underlying the pathogenetic mechanism of dysferlinopathy is not completely understood.
These findings suggest that increasing the amount of misfolded dysferlin using small molecules could represent an effective future clinical treatment for dysferlinopathy.
Dysferlinopathy is characterized by absence or marked reduction of dysferlin protein with 43% of reported pathogenic variants being missense variants that span the length of the dysferlin protein.
We have observed that dysferlinopathy patient biopsies show an excess of immature fibres and therefore investigated the role of dysferlin in muscle regeneration.
Dysferlin is likely required for maintaining the structural integrity of the muscle fiber plasma membrane, and plasma membrane injury is an early event in the pathogenesis of dysferlinopathy.
Additional findings of histopathology, specific stain for sarcolemmal membrane protein, Western blot analysis and clinical presentation clinched the diagnosis further of dysferlinopathy (LGMD2B) in both our patients.
Our findings indicate that muscle membrane disruption and myofiber degeneration in dysferlinopathy were directly mediated by the loss of dysferlin via a new pathogenic mechanism in muscular dystrophies.
We quantified dysferlin protein levels in PBMC lysates of 77 individuals suspected clinically of having a dysferlinopathy to screen for true positives.
Here, we analysed the mutational data from the largest cohort described to date, a cohort of 134 patients, included based on clinical suspicion of primary dysferlinopathy and/or dysferlin protein deficiency identified on muscle biopsy samples.