Treatment with Recombinant Human MG53 Protein Increases Membrane Integrity in a Mouse Model of Limb Girdle Muscular Dystrophy 2B

Abstract

Limb girdle muscular dystrophy type 2B (LGMD2B) and other dysferlinopathies are degenerative muscle diseases that result from mutations in the dysferlin gene and have limited treatment options. The dysferlin protein has been linked to multiple cellular functions including a Ca-dependent membrane repair process that reseals disruptions in the sarcolemmal membrane. Recombinant human MG53 protein (rhMG53) can increase the membrane repair process in multiple cell types both in vitro and in vivo. Here, we tested whether rhMG53 protein can improve membrane repair in a dysferlin-deficient mouse model of LGMD2B (B6.129-Dysf/J). We found that rhMG53 can increase the integrity of the sarcolemmal membrane of isolated muscle fibers and whole muscles in a Ca-independent fashion when assayed by a multi-photon laser wounding assay. Intraperitoneal injection of rhMG53 into mice before acute eccentric treadmill exercise can decrease the release of intracellular enzymes from skeletal muscle and decrease the entry of immunoglobulin G and Evans blue dye into muscle fibers in vivo. These results indicate that short-term rhMG53 treatment can ameliorate one of the underlying defects in dysferlin-deficient muscle by increasing sarcolemmal membrane integrity. We also provide evidence that rhMG53 protein increases membrane integrity independently of the canonical dysferlin-mediated, Ca-dependent pathway known to be important for sarcolemmal membrane repair.

The Limb–Girdle Muscular Dystrophies: Is Treatment on the Horizon?

“…They found that intraperitoneal injection of rhMG53 into mice before acute eccentric treadmill exercise can decrease the release of intracellular enzymes from skeletal muscles and decrease the entry of immunoglobulin G and Evans blue dye into muscle fibers in vivo, suggesting increased integrity of the sarcolemmal membrane. This is independent of the known dysferlin-mediated Ca 2+ -dependent pathway for sarcolemmal membrane repair [27].…”

“…Plasmid DNA has been investigated as a tool to deliver the large dysferlin protein since plasmid has no size limit, is not immunogenic, is cheaper to produce, and has the potential to integrate into the genome if an integration mechanism is provided [27]. Encouraged by the result of Wolff et al's investigation using plasmid DNA as a vector for carrying the large dystrophin gene to mdx mouse models and another study demonstrating that co-delivery of follistatin with the dystrophin gene can be beneficial in mdx mouse models of Duchenne muscular dystrophy [32][33][34], Ma et al in 2017 studied the intravascular codelivery of dysferlin with follistatin (FST) gene into all major muscle groups of the hind limb of dysferlin knockout mice.…”

Cellular mechanisms and signals that coordinate plasma membrane repair

“…PS binding in conjunction with oxidation-dependent oligomerization allows MG53 to aid in trafficking of dysferlin-containing vesicles to the plasma membrane for fusion (Figure 4a) [109,113]. However, exogenous MG53 exposure can also improve membrane repair in dysferlin-null mice [114]. Therefore, instead of oxidation-dependent vesicle fusion, oxidized MG53 may aid in little explored extracellular pathways for plasma membrane repair [115].…”

Globular Polymer Grafts Require a Critical Size for Efficient Molecular Sieving of Enzyme Substrates

“…[1][2][3][4][5][6][7][8] One potential approach to achieving these goals involves decoration of the protein surface with polymeric structures,w hich has been shown to improve protein pharmacokinetics and reduce immunogenicity. [1][2][3][4][5][6][7][8] One potential approach to achieving these goals involves decoration of the protein surface with polymeric structures,w hich has been shown to improve protein pharmacokinetics and reduce immunogenicity.…”

“…Theincreasingutilityofprotein-basedtherapeuticagentshas spawned efforts to improve their efficacyand in vivo stability, while reducing their immunogenicity. [1][2][3][4][5][6][7][8] One potential approach to achieving these goals involves decoration of the protein surface with polymeric structures,w hich has been shown to improve protein pharmacokinetics and reduce immunogenicity. [9][10][11] Arguably,t he most prevalent polymer used for protein conjugation is poly(ethylene glycol) (PEG), [12][13][14] which has been introduced on the surface of many proteins.…”