Minimal expression of dysferlin prevents development of muscular dystrophy in dysferlin exon 40a knockout mice

ABSTRACT: Dysferlin is an essential muscle membrane repair protein and autosomal recessive mutations in its gene result in progressive muscular dystrophies collectively called dysferlinopathies. We previously showed that calpain-mediated cleavage within dysferlin exon 40a releases a 72kDa C-terminal minidysferlin recruited to injured sarcolemma. In the current study, we hypothesised that knocking out exon 40a will lead to defective membrane repair and development of muscular dystrophy over time. To address this hypothesis, we created three exon 40a knockout (40aKO) mouse lines with dysferlin protein levels ranging from ~80% of wildtype (WT) in 40aKO-3, ~50% in 40aKO-2 and ~10-20% in 40aKO-1 mice. Histopathological analysis of skeletal muscles harvested from all 12-month-old 40aKO mice showed little evidence of dystrophic features seen in dysferlin-null BLAJ mice. Lipidomics analysis on 18wk old quadriceps showed that all 40aKO lines had a similar lipidomic profile to WT and distinct from BLAJs. The proteomic profile of 40aKO lines was intermediate between that of WT and BLAJs. Laser membrane damage assays showed normal membrane repair capacity in all three 40aKO lines. These results collectively indicate that ~10-20% of dysferlin protein expression is sufficient for maintenance of the lipidome and membrane repair capacity, and crucially prevents development of muscular dystrophy.

INSTRUMENT(S):

ORGANISM(S): Mus Musculus (mouse)

TISSUE(S): Skeletal Muscle, Forelimb Muscle

DISEASE(S): Limb-girdle Muscular Dystrophy

SUBMITTER: Chi Nam Ignatius Pang  

LAB HEAD: Chi Nam Ignatius Pang

PROVIDER: PXD035393 | Pride | 2023-03-11

REPOSITORIES: Pride