O'Brien, J. G. | bioRxiv Science

bioRxiv2023

The super-healing MRL strain promotes muscle growth in muscular dystrophy through a regenerative extracellular matrix

Genetic background shifts the severity of muscular dystrophy. In mice, the DBA/2J strain confers a more severe muscular dystrophy phenotype, whereas the Murphys Roth Large (MRL) strain has "super-healing" properties that reduce fibrosis. A comparative analysis of the Sgcg null model of Limb Girdle Muscular Dystrophy in the DBA/2J versus MRL strain showed the MRL background was associated with greater myofiber regeneration and reduced structural degradation of muscle. Transcriptomic profiling of dystrophic muscle in the DBA/2J and MRL strains indicated strain-dependent expression of the extracellular matrix (ECM) and TGF-{beta} signaling genes. To investigate the MRL ECM, cellular components were removed from dystrophic muscle sections to generate decellularized "myoscaffolds". Decellularized myoscaffolds from dystrophic mice in the protective MRL strain had significantly less deposition of collagen and matrix-bound TGF-{beta}1 and TGF-{beta}3 throughout the matrix, and dystrophic myoscaffolds from the MRL background were enriched in myokines. C2C12 myoblasts were seeded onto decellularized matrices from Sgcg-/- MRL and Sgcg-/- DBA/2J matrices. Acellular myoscaffolds from the dystrophic MRL background induced myoblast differentiation and growth compared to dystrophic myoscaffolds from the DBA/2J matrices. These studies establish that the MRL background also generates its effect through a highly regenerative ECM, which is active even in muscular dystrophy. Brief SummaryThe extracellular matrix of the super-healing MRL mouse strain harbors regenerative myokines that improve skeletal muscle growth and function in muscular dystrophy. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=120 SRC="FIGDIR/small/547098v1_ufig1.gif" ALT="Figure 1"> View larger version (49K): org.highwire.dtl.DTLVardef@18543eborg.highwire.dtl.DTLVardef@2e3386org.highwire.dtl.DTLVardef@138d5ccorg.highwire.dtl.DTLVardef@5c4ef6_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2022

Myoscaffolds demonstrate differential matrix components across muscular dystrophies

Extracellular matrix (ECM) pathologic remodeling underlies many fibrotic disorders, including muscular dystrophy. Tissue decellularization removes cellular components while leaving behind ECM components. We generated "on-slide" decellularized tissue slices from genetically distinct dystrophic mouse models. The ECM of dystrophin-and sarcoglycan-deficient muscles had marked thrombospondin 4 deposition, while dysferlin-deficient muscle had excess decorin. Annexins A2 and A6 were present on all dystrophic decellularized ECMs, but annexin matrix deposition was excessive in dysferlin-deficient muscular dystrophy. Adeno-associated viral expression of annexin A6 specifically in muscle resulted in annexin A6 deposition throughout the ECM, indicating muscle as a source of this ECM protein. C2C12 myoblasts seeded onto decellularized matrices displayed differential myoblast mobility. Dystrophin-deficient decellularized matrices inhibited myoblast mobility while dysferlin-deficient decellularized matrices enhanced myoblast movement. Myoblasts treated with recombinant annexin A6 increased mobillity similar to that seen on dysferlin-deficient decellularized matrix. These findings demonstrate specific fibrotic signatures elicit effects on myoblast activity. TEASERFibrosis in muscular dystrophy has differential effects on myoblasts HIGHLIGHTSO_LISpatial architecture and composition of the ECM differ across genetically distinct forms of muscular dystrophy, especially with respect to Annexin A6 protein deposition C_LIO_LIMatrix from dystrophin-mediated muscular dystrophy inhibits myoblast movement C_LIO_LIMatrix from dysferlin-deficient muscular dystrophy promotes myoblast motility C_LIO_LIAnnexin A6 was sufficient to enhance myoblast motility C_LI

molecular biology↗