title: Drosophila Kette coordinates myoblast junction dissolution and the ratio of Scar-to-WASp during myoblast fusion.
abstract: The fusion of founder cells and fusion-competent myoblasts (FCMs) is crucial for muscle formation in Drosophila Characteristic events of myoblast fusion include the recognition and adhesion of myoblasts, and the formation of branched F-actin by the Arp2/3 complex at the site of cell-cell contact. At the ultrastructural level, these events are reflected by the appearance of finger-like protrusions and electron-dense plaques that appear prior to fusion. Severe defects in myoblast fusion are caused by the loss of Kette (a homolog of Nap1 and Hem-2, also known as NCKAP1 and NCKAP1L, respectively), a member of the regulatory complex formed by Scar or WAVE proteins (represented by the single protein, Scar, in flies). kette mutants form finger-like protrusions, but the electron-dense plaques are extended. Here, we show that the electron-dense plaques in wild-type and kette mutant myoblasts resemble other electron-dense structures that are known to function as cellular junctions. Furthermore, analysis of double mutants and attempts to rescue the kette mutant phenotype with N-cadherin, wasp and genes of members of the regulatory Scar complex revealed that Kette has two functions during myoblast fusion. First, Kette controls the dissolution of electron-dense plaques. Second, Kette controls the ratio of the Arp2/3 activators Scar and WASp in FCMs.
authors: Philipps-Universität Marburg, FB Biologie, Entwicklungsbiologie, Karl-von-Frisch Str. 8, Marburg 35043, Germany.
authors: Julia
authors: J
authors: Hamp
authors: Philipps-Universität Marburg, FB Biologie, Entwicklungsbiologie, Karl-von-Frisch Str. 8, Marburg 35043, Germany.
authors: Andreas
authors: A
authors: Löwer
authors: Philipps-Universität Marburg, FB Biologie, Entwicklungsbiologie, Karl-von-Frisch Str. 8, Marburg 35043, Germany.
authors: Christine
authors: C
authors: Dottermusch-Heidel
authors: Fachbereich Biologie, Spezielle Zoologie, Philipps-Universität Marburg, Karl-von-Frisch Str. 8, Marburg 35043, Germany.
authors: Lothar
authors: L
authors: Beck
authors: Interfaculty Institute for Cell Biology, Section Animal Genetics, University of Tübingen, Tübingen 72076, Germany.
authors: Bernard
authors: B
authors: Moussian
authors: Max Planck Institute for Developmental Biology, Section Electron Microscopy, Tübingen 72076, Germany.
authors: Matthias
authors: M
authors: Flötenmeyer
authors: Philipps-Universität Marburg, FB Biologie, Entwicklungsbiologie, Karl-von-Frisch Str. 8, Marburg 35043, Germany oenel@staff.uni-marburg.de.
authors: Susanne-Filiz
authors: 0000-0003-3081-477X
authors: SF
authors: Önel
mesh_terms: D000818:Animals; D015820:Cadherins / Q000378:metabolism; D002459:Cell Fusion; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000166:cytology* / Q000378:metabolism*; D007365:Intercellular Junctions / Q000378:metabolism*; D008840:Microfilament Proteins / Q000378:metabolism*; D008954:Models, Biological; D009154:Mutation / Q000235:genetics; D032446:Myoblasts / Q000166:cytology* / Q000378:metabolism* / Q000648:ultrastructure; D010641:Phenotype; D051316:Wiskott-Aldrich Syndrome Protein / Q000378:metabolism*; D020830:rac1 GTP-Binding Protein / Q000378:metabolism
chemical_list: D015820:Cadherins; D029721:Drosophila Proteins; D008840:Microfilament Proteins; C449671:SCAR protein, Drosophila; C477859:WASp protein, Drosophila; D051316:Wiskott-Aldrich Syndrome Protein; C478569:hem protein, Drosophila; D020830:rac1 GTP-Binding Protein
keywords: Cellular junction; F-actin; Myoblast fusion; Myogenesis; Vrp1; WAVE; Wip