title: A critical function for the actin cytoskeleton in targeted exocytosis of prefusion vesicles during myoblast fusion.
abstract: Myoblast fusion is an essential step during muscle differentiation. Previous studies in Drosophila have revealed a signaling pathway that relays the fusion signal from the plasma membrane to the actin cytoskeleton. However, the function for the actin cytoskeleton in myoblast fusion remains unclear. Here we describe the characterization of solitary (sltr), a component of the myoblast fusion signaling cascade. sltr encodes the Drosophila ortholog of the mammalian WASP-interacting protein. Sltr is recruited to sites of fusion by the fusion-competent cell-specific receptor Sns and acts as a positive regulator for actin polymerization at these sites. Electron microscopy analysis suggests that formation of F-actin-enriched foci at sites of fusion is involved in the proper targeting and coating of prefusion vesicles. These studies reveal a surprising cell-type specificity of Sltr-mediated actin polymerization in myoblast fusion, and demonstrate that targeted exocytosis of prefusion vesicles is a critical step prior to plasma membrane fusion.
authors.affiliation: Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
authors.forename: Sangjoon
authors.initials: S
authors.lastname: Kim
authors.forename: Khurts
authors.initials: K
authors.lastname: Shilagardi
authors.forename: Shiliang
authors.initials: S
authors.lastname: Zhang
authors.forename: Sabrina N
authors.initials: SN
authors.lastname: Hong
authors.forename: Kristin L
authors.initials: KL
authors.lastname: Sens
authors.forename: Jinyan
authors.initials: J
authors.lastname: Bo
authors.forename: Guillermo A
authors.initials: GA
authors.lastname: Gonzalez
authors.forename: Elizabeth H
authors.initials: EH
authors.lastname: Chen
mesh_terms: D000199:Actins / Q000378:metabolism* / Q000502:physiology; D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D002459:Cell Fusion; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D004331:Drosophila melanogaster / Q000196:embryology / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D004625:Embryo, Nonmammalian; D005089:Exocytosis; D051379:Mice; D008954:Models, Biological; D008969:Molecular Sequence Data; D024510:Muscle Development; D032446:Myoblasts / Q000378:metabolism / Q000502:physiology*; D050737:Proto-Oncogene Proteins c-crk / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014162:Transfection; D022161:Transport Vesicles / Q000378:metabolism; D051316:Wiskott-Aldrich Syndrome Protein / Q000235:genetics / Q000378:metabolism
chemical_list: D000199:Actins; D029721:Drosophila Proteins; D050737:Proto-Oncogene Proteins c-crk; C477859:WASp protein, Drosophila; D051316:Wiskott-Aldrich Syndrome Protein