title: Myogenesis in dysferlin-deficient myoblasts is inhibited by an intrinsic inflammatory response.
abstract: Limb-girdle muscular dystrophy type 2B results from mutations in dysferlin, a membrane-associated protein involved in cellular membrane repair. Primary myoblast cultures derived from dysferlinopathy patients show reduced myogenic potential, suggesting that dysferlin may regulate myotube fusion and be required for muscle regeneration. These observations contrast with the findings that muscle develops normally in pre-symptomatic dysferlinopathy patients. To better understand the role of dysferlin in myogenesis, we investigated this process in vitro using cells derived from two mouse models of dysferlinopathy: SJL/J and A/J mice. We observed that myotubes derived from dysferlin-deficient muscle were of significantly smaller diameters, contained fewer myonuclei, and displayed reduced myogenic gene expression compared to dysferlin-sufficient cells. Together, these findings suggest that the absence of dysferlin from myoblasts is detrimental to myogenesis. Pro-inflammatory NFκB signaling was upregulated in dysferlin-deficient myotubes; the anti-inflammatory agent celastrol reduced the NFκB activation and improved myogenesis in dysferlin-deficient cultures. The results suggest that decreased myotube fusion in dysferlin deficiency is attributable to intrinsic inflammatory activation and can be improved using anti-inflammatory mediators.
authors.affiliation: Research Center for Genetic Medicine, Children's National Medical Center, 111 Michigan Avenue NW, Washington, DC 20010, USA.
authors.forename: Tatiana V
authors.initials: TV
authors.lastname: Cohen
authors.forename: Jonathan E
authors.initials: JE
authors.lastname: Cohen
authors.forename: Terence A
authors.initials: TA
authors.lastname: Partridge
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology; D037282:Calreticulin / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D000073939:Dysferlin; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics*; D015395:Histocompatibility Antigens Class I / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000172:deficiency*; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D024510:Muscle Development / Q000187:drug effects / Q000235:genetics*; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism; D018482:Muscle, Skeletal / Q000166:cytology; D009154:Mutation / Q000235:genetics; D016328:NF-kappa B / Q000378:metabolism; D053978:Pentacyclic Triterpenes; D032496:Satellite Cells, Skeletal Muscle / Q000187:drug effects / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D013997:Time Factors; D051996:Transcription Factor RelA / Q000235:genetics / Q000378:metabolism; D014315:Triterpenes / Q000494:pharmacology
chemical_list: D000893:Anti-Inflammatory Agents; D037282:Calreticulin; C497505:Dysf protein, mouse; D000073939:Dysferlin; D015395:Histocompatibility Antigens Class I; D008565:Membrane Proteins; D009124:Muscle Proteins; D016328:NF-kappa B; D053978:Pentacyclic Triterpenes; C498144:Rela protein, mouse; D051996:Transcription Factor RelA; D014315:Triterpenes; C050414:celastrol