Dual AAV amelioration of Lama2-null muscular dystrophy and neuropathy
The dy3K/dy3K Lama2-/- mouse is a model for the severe form of LAMA2-related dystrophy and peripheral neuropathy (LAMA2-RD). In the dystrophic mice, a compensating laminin subunit, Lm4, that lacks polymerization and -dystroglycan-binding activity, replaces the missing Lm2 subunit. It was previously found that an 4-laminin can be modified with two small laminin-binding linker proteins, i.e. LNNd{Delta}G2 and miniagrin to facilitate polymerization and -dystroglycan binding respectively, to enable the key missing functions. Adeno-associated virus serotype 9 (AAV9) was used to deliver minigenes coding for the two proteins in dystrophic mice. AAV9-LNNd{Delta}G2 utilized a universal CBh promoter while AAV9-miniagrin utilized either the CBh promoter or muscle-specific SPc5-12 promoter. The phenotype in the dy3K/dy3K mice was evaluated following i.v. postnatal injection with either AAV9 -LNNd{Delta}G2 alone or in combination with AAV9- LNNd{Delta}G2 + AAV9- miniagrin. Double AAV treatment was found to substantially increase survival and ambulation, as well as increase forelimb grip-strength and improve muscle histology. Of note, the sciatic nerve amyelination characteristic of laminin 2-deficiency was prevented. While single treatment with LNNd{Delta}G2 was inferior to double treatment for muscle strength and survival, it corrected the radial sorting deficit equally, revealing that enablement of laminin polymerization is a sufficient requirement for myelination. HighlightsO_LIThe dy3K/dy3K (Lama2-/-) mouse, a model for severe LAMA2-related dystrophy, expresses laminin-411 that is unable to polymerize or bind to -dystroglycan (DG). C_LIO_LILNNd{Delta}G2 and miniagrin are laminin-411-binding proteins that enable polymerization and DG binding. C_LIO_LIAAV9 delivery of genes coding for LNNd{Delta}G2 and miniagrin ameliorated the dystrophic phenotype in muscle and nerve (survival, growth, mobility, and grip-strength, muscle and nerve histopathology). C_LIO_LISciatic nerve amyelination was prevented by LNNd{Delta}G2 alone. C_LI