An agrin minigene rescues dystrophic symptoms in a mouse model for congenital muscular dystrophy

Abstract

Congenital muscular dystrophy is a heterogeneous and severe, progressive muscle-wasting disease that frequently leads to death in early childhood. Most cases of congenital muscular dystrophy are caused by mutations in LAMA2, the gene encoding the alpha2 chain of the main laminin isoforms expressed by muscle fibres. Muscle fibre deterioration in this disease is thought to be caused by the failure to form the primary laminin scaffold, which is necessary for basement membrane structure, and the missing interaction between muscle basement membrane and the dystrophin-glycoprotein complex (DGC) or the integrins. With the aim to restore muscle function in a mouse model for this disease, we have designed a minigene of agrin, a protein known for its role in the formation of the neuromuscular junction. Here we show that this mini-agrin-which binds to basement membrane and to alpha-dystroglycan, a member of the DGC-amends muscle pathology by a mechanism that includes agrin-mediated stabilization of alpha-dystroglycan and the laminin alpha5 chain. Our data provides in vivo evidence that a non-homologous protein in combination with rational protein design can be used to devise therapeutic tools that may restore muscle function in human muscular dystrophies.

Congenital muscular dystrophy. Part II: a review of pathogenesis and therapeutic perspectives

“…From 1994, knock-out mouse or spontaneous mutant mouse strains have been identified as animal models for MDC1A with total and partial deficiency [99][100][101][102][103][104][105] , and experimental therapeutic strategies have been attempted 102,103,[106][107][108][109][110][111][112][113][114][115][116] . In mice, Kuang et al 102,103 were successful in obtaining the expression of a human laminin alpha 2 chain transgene under the regulation of a muscle-specific creatine kinase promoter.…”

“…In addition, the success of myoblast transplantation depends on future advances for controlling the immune response of the receptor and his biochemical adequacy with the donor. In dy W /dy W mice a "replacement therapy" using a mini-agrin (miniaturized form of agrin) resulted in a lesser muscle degeneration and in a decrease of mortality that is mediated through the linking of muscle basement membrane to the DGC, and not to integrin 107 . The first attempt of somatic gene therapy to treat mice with laminin alpha-2 deficiency was performed by Qiao et al 108 .…”

The genetic and molecular basis of muscular dystrophy: roles of cell–matrix linkage in the pathogenesis

“…Thus, the laminin polymer scaffold appears to be necessary for the organization of the basement membrane and the interaction between the matrix and cell membranes, both of which are essential for maintenance of the skeletal muscle functions. Interestingly, mini-agrin, which retains binding affinities to both DG and laminin a4-and a5-chains (up-regulated a-chains in laminin a2-deficient muscle), is shown to be able to compensate for loss of the laminin a2-chain in dy W mice by establishing an alternative DG-matrix linkage (Moll et al 2001). Laminin-receptor interaction is also thought to be involved in the apoptotic pathway that may underlie the pathogenesis of muscular dystrophy because of the increased signs of apoptosis that were reported in laminin-2-deficient mice and human patients (Miyagoe et al 1997;Hayashi et al 2001).…”

“…As already mentioned, reinforcement of the linkage between DG and matrix proteins by LARGE or mini agrin expression (Moll et al 2001) is an intriguing strategy for dystroglycanopathies and laminin-deficient muscular dystrophies, respectively. As for DMD, utrophin is a target protein for the compensation of dystrophin defects.…”

ADAM12 Alleviates the Skeletal Muscle Pathology in mdx Dystrophic Mice

“…11 In case of dy mice, an artificial miniagrin was used to cross-link proteins into a basement membrane-like matrix to compensate for lack of laminin-2 and -4. Surprisingly, overexpression of proteins that are normally confined to the neuromuscular junction such as utrophin, 37 ␣7 integrin, 38 GalNAc transferase, 12 and the agrin minigene 39 have localized these proteins all along the plasma membrane with subsequent benefit for the diseased muscle. The exact molecular mechanisms for this distribution and beneficial effect, however, are not clear.…”