title: Differences in the expression and distribution of flotillin-2 in chick, mice and human muscle cells.
abstract: Myoblasts undergo a series of changes in the composition and dynamics of their plasma membranes during the initial steps of skeletal muscle differentiation. These changes are crucial requirements for myoblast fusion and allow the formation of striated muscle fibers. Membrane microdomains, or lipid rafts, have been implicated in myoblast fusion. Flotillins are scaffold proteins that are essential for the formation and dynamics of lipid rafts. Flotillins have been widely studied over the last few years, but still little is known about their role during skeletal muscle differentiation. In the present study, we analyzed the expression and distribution of flotillin-2 in chick, mice and human muscle cells grown in vitro. Primary cultures of chick myogenic cells showed a decrease in the expression of flotillin-2 during the first 72 hours of muscle differentiation. Interestingly, flotillin-2 was found to be highly expressed in chick myogenic fibroblasts and weakly expressed in chick myoblasts and multinucleated myotubes. Flotillin-2 was distributed in vesicle-like structures within the cytoplasm of chick myogenic fibroblasts, in the mouse C2C12 myogenic cell line, and in neonatal human muscle cells. Cryo-immunogold labeling revealed the presence of flotillin-2 in vesicles and in Golgi stacks in chick myogenic fibroblasts. Further, brefeldin A induced a major reduction in the number of flotillin-2 containing vesicles which correlates to a decrease in myoblast fusion. These results suggest the involvement of flotillin-2 during the initial steps of skeletal myogenesis.
authors.affiliation: Laboratório de Diferenciação Muscular e Citoesqueleto, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Ana Claudia Batista
authors.initials: AC
authors.lastname: Possidonio
authors.affiliation: Laboratório de Diferenciação Muscular e Citoesqueleto, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Carolina Pontes
authors.initials: CP
authors.lastname: Soares
authors.affiliation: Université Pierre et Marie Curie Paris 6, Paris, France.
authors.forename: Débora Morueco
authors.initials: DM
authors.lastname: Portilho
authors.affiliation: Laboratório de Ultraestrutura Celular, Universidade Santa Úrsula, Rio de Janeiro, Brazil.
authors.forename: Victor
authors.initials: V
authors.lastname: Midlej
authors.affiliation: Laboratório de Ultraestrutura Celular, Universidade Santa Úrsula, Rio de Janeiro, Brazil.
authors.forename: Marlene
authors.initials: M
authors.lastname: Benchimol
authors.affiliation: Université Pierre et Marie Curie Paris 6, Paris, France.
authors.forename: Gillian
authors.initials: G
authors.lastname: Butler-Browne
authors.affiliation: Laboratório de Diferenciação Muscular e Citoesqueleto, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Manoel Luis
authors.initials: ML
authors.lastname: Costa
authors.affiliation: Laboratório de Diferenciação Muscular e Citoesqueleto, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Claudia
authors.initials: C
authors.lastname: Mermelstein
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D020126:Brefeldin A / Q000378:metabolism; D002642:Chick Embryo; D020285:Cryoelectron Microscopy; D022162:Cytoplasmic Vesicles / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D005455:Fluorescent Antibody Technique; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D046529:Microscopy, Electron, Transmission; D018482:Muscle, Skeletal / Q000196:embryology* / Q000378:metabolism; D032446:Myoblasts / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D013045:Species Specificity
chemical_list: D017931:DNA Primers; D008565:Membrane Proteins; C106354:flotillins; D020126:Brefeldin A
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