Exon Skipping in a Dysf-Missense Mutant Mouse Model

Area of Science:

• Biochemistry
• Genetics
• Molecular Biology

Background:

• Limb girdle muscular dystrophy 2B (LGMD2B) is an inherited muscle-wasting disease caused by mutations in the dysferlin gene (DYSF).
• Missense mutations in DYSF lead to protein aggregation, amyloid formation, and impaired membrane repair, contributing to disease progression.
• Existing dysferlin-null mouse models do not fully recapitulate the complexities of missense mutation-induced LGMD2B.

Purpose of the Study:

• To develop and characterize a novel mouse model that accurately reflects missense mutation-induced dysferlinopathy.
• To evaluate the efficacy of an exon-skipping strategy in this new animal model.

Main Methods:

• Generated a mouse model (MMex38) with a specific missense mutation in exon 38 of the dysferlin gene, analogous to a human variant.
• Assessed the model for key pathological features including progressive muscle wasting, amyloid formation, and membrane repair defects.
• Utilized U7 small nuclear RNA (snRNA)-based splice switching to induce exon skipping of Dysf exons 37 and 38 in vivo.

Main Results:

• The MMex38 mouse model exhibited progressive muscular dystrophy, amyloid formation, and impaired sarcolemmal repair, mirroring human missense mutant dysferlinopathy.
• Successful in vivo skipping of Dysf exons 37 and 38 was achieved using the U7 snRNA-based splice switching strategy.
• This model allows for the study of missense mutation consequences, which are not evident in dysferlin-null models.

Conclusions:

• The MMex38 mouse model is a valuable preclinical tool for studying missense dysferlinopathy.
• This model facilitates the development and testing of targeted therapeutic strategies, such as exon skipping, for LGMD2B.
• The successful demonstration of exon skipping offers a promising avenue for future LGMD2B treatments.