title: Cholesterol depletion by methyl-beta-cyclodextrin enhances myoblast fusion and induces the formation of myotubes with disorganized nuclei.
abstract: The formation of a skeletal muscle fiber begins with the withdrawal of committed mononucleated precursors from the cell cycle. These myoblasts elongate while aligning with each other, guided by recognition between their membranes. This step is followed by cell fusion and the formation of long striated multinucleated myotubes. We used methyl-beta-cyclodextrin (MCD) in primary cultured chick skeletal muscle cells to deplete membrane cholesterol and investigate its role during myogenesis. MCD promoted a significant increase in the expression of troponin T, enhanced myoblast fusion, and induced the formation of large multinucleated myotubes with nuclei being clustered centrally and not aligned at the cell periphery. MCD myotubes were striated, as indicated by sarcomeric alpha-actinin staining, and microtubule and desmin filament distribution was not altered. Pre-fusion MCD-treated myoblasts formed large aggregates, with cadherin and beta-catenin being accumulated in cell adhesion contacts. We also found that the membrane microdomain marker GM1 was not present as clusters in the membrane of MCD-treated myoblasts. Our data demonstrate that cholesterol is involved in the early steps of skeletal muscle differentiation.
authors.affiliation: Laboratório de Diferenciação Muscular e Citoesqueleto, Departamento de Histologia e Embriologia, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21949-590, Brazil. mermelstein@ufrj.br
authors.forename: Cláudia S
authors.initials: CS
authors.lastname: Mermelstein
authors.forename: Débora M
authors.initials: DM
authors.lastname: Portilho
authors.forename: Rommel B
authors.initials: RB
authors.lastname: Medeiros
authors.forename: Aline R
authors.initials: AR
authors.lastname: Matos
authors.forename: Marcelo
authors.initials: M
authors.lastname: Einicker-Lamas
authors.forename: Giovane G
authors.initials: GG
authors.lastname: Tortelote
authors.forename: Adalberto
authors.initials: A
authors.lastname: Vieyra
authors.forename: Manoel L
authors.initials: ML
authors.lastname: Costa
mesh_terms: D000185:Actinin / Q000378:metabolism; D000818:Animals; D015820:Cadherins / Q000096:biosynthesis; D002454:Cell Differentiation; D002459:Cell Fusion; D002467:Cell Nucleus / Q000187:drug effects* / Q000473:pathology; D002478:Cells, Cultured; D002642:Chick Embryo; D002784:Cholesterol / Q000032:analysis / Q000378:metabolism*; D003598:Cytoskeletal Proteins / Q000096:biosynthesis; D016650:Fluorescein-5-isothiocyanate; D019084:Fluorescent Antibody Technique, Indirect; D005456:Fluorescent Dyes; D018613:Microscopy, Confocal; D008954:Models, Biological; D024510:Muscle Development; D018485:Muscle Fibers, Skeletal / Q000187:drug effects*; D018482:Muscle, Skeletal / Q000166:cytology; D032446:Myoblasts / Q000187:drug effects*; D012235:Rhodamines; D015534:Trans-Activators / Q000096:biosynthesis; D020107:Troponin T / Q000187:drug effects / Q000378:metabolism; D051176:beta Catenin; D047392:beta-Cyclodextrins / Q000494:pharmacology*
chemical_list: D015820:Cadherins; D003598:Cytoskeletal Proteins; D005456:Fluorescent Dyes; D012235:Rhodamines; D015534:Trans-Activators; D020107:Troponin T; D051176:beta Catenin; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; D000185:Actinin; C009434:tetramethylrhodamine isothiocyanate; D002784:Cholesterol; D016650:Fluorescein-5-isothiocyanate