title: Cytoskeleton/stretch-activated ion channel interaction regulates myogenic differentiation of skeletal myoblasts.
abstract: In the present study, we investigated the functional interaction between stress fibers (SFs) and stretch-activated channels (SACs) and its possible role in the regulation of myoblast differentiation induced by switch to differentiation culture in the presence or absence of sphingosine 1-phosphate. It was found that there was a clear temporal correlation between SF formation and SAC activation in differentiating C2C12 myoblasts. Inhibition of actin polymerization with the specific Rho kinase inhibitor Y-27632, significantly decreased SAC sensitivity in these cells, suggesting a role for Rho-dependent actin remodeling in the regulation of the channel opening. The alteration of cytoskeletal/SAC functional correlation had also deleterious effects on myogenic differentiation of C2C12 cells as judged by combined confocal immunofluorescence, biochemical and electrophysiological analyses. Indeed, the treatment with Y-27632 or with DHCB, an actin disrupting agent, inhibited the expression of the myogenic markers (myogenin and sarcomeric proteins) and myoblast-myotube transition. The treatment with the channel blocker, GdCl(3), also affected myogenesis in these cells. It impaired, in fact, myoblast phenotypic maturation (i.e., reduced the expression of alpha-sarcomeric actin and skeletal myosin and the activity of creatine kinase) but did not modify promoter activity and protein expression levels of myogenin. The results of this study, together with being in agreement with the general idea that cytoskeletal remodeling is essential for muscle differentiation, describe a novel pathway whereby the formation of SFs and their contraction, generate a mechanical tension to the plasma membrane, activate SACs and trigger Ca(2+)-dependent signals, thus influencing the phenotypic maturation of myoblasts.
authors.affiliation: Department of Anatomy, Histology and Forensic Medicine, University of Florence, Florence, Italy.
authors.forename: Lucia
authors.initials: L
authors.lastname: Formigli
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Meacci
authors.forename: Chiara
authors.initials: C
authors.lastname: Sassoli
authors.forename: Roberta
authors.initials: R
authors.lastname: Squecco
authors.forename: Daniele
authors.initials: D
authors.lastname: Nosi
authors.forename: Flaminia
authors.initials: F
authors.lastname: Chellini
authors.forename: Fabio
authors.initials: F
authors.lastname: Naro
authors.forename: Fabio
authors.initials: F
authors.lastname: Francini
authors.forename: Sandra
authors.initials: S
authors.lastname: Zecchi-Orlandini
mesh_terms: D000199:Actins / Q000378:metabolism; D000577:Amides / Q000494:pharmacology; D000818:Animals; D020013:Calcium Signaling; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D003571:Cytochalasin B / Q000031:analogs & derivatives / Q000494:pharmacology; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005682:Gadolinium / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism*; D008246:Lysophospholipids / Q000494:pharmacology; D008564:Membrane Potentials; D051379:Mice; D018613:Microscopy, Confocal; D024510:Muscle Development / Q000187:drug effects; D009470:Muscle Spindles / Q000187:drug effects / Q000378:metabolism*; D032448:Myoblasts, Skeletal / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D010641:Phenotype; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D011725:Pyridines / Q000494:pharmacology; D013110:Sphingosine / Q000031:analogs & derivatives / Q000494:pharmacology; D022502:Stress Fibers / Q000378:metabolism; D013997:Time Factors; D054460:rho-Associated Kinases
chemical_list: D000199:Actins; D000577:Amides; D004791:Enzyme Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D007473:Ion Channels; D008246:Lysophospholipids; D011725:Pyridines; C108830:Y 27632; C060506:sphingosine 1-phosphate; C024794:dihydrocytochalasin B; D003571:Cytochalasin B; D005682:Gadolinium; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D013110:Sphingosine; C038958:gadolinium chloride