title: The actin nucleator WASp is required for myoblast fusion during adult Drosophila myogenesis.
abstract: Myoblast fusion provides a fundamental, conserved mechanism for muscle fiber growth. We demonstrate here that the functional contribution of Wsp, the Drosophila homolog of the conserved actin nucleation-promoting factor (NPF) WASp, is essential for myoblast fusion during the formation of muscles of the adult fly. Disruption of Wsp function results in complete arrest of myoblast fusion in all muscles examined. Wsp activity during adult Drosophila myogenesis is specifically required for muscle cell fusion and is crucial both for the formation of new muscle fibers and for the growth of muscles derived from persistent larval templates. Although Wsp is expressed both in fibers and individual myoblasts, its activity in either one of these cell types is sufficient. SCAR, a second major Arp2/3 NPF, is also required during adult myoblast fusion. Formation of fusion-associated actin 'foci' is dependent on Arp2/3 complex function, but appears to rely on a distinct, unknown nucleator. The comprehensive nature of these requirements identifies Arp2/3-based branched actin polymerization as a universal mechanism underlying myoblast fusion.
authors.affiliation: National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore 560065, India.
authors.forename: Priyankana
authors.initials: P
authors.lastname: Mukherjee
authors.forename: Boaz
authors.initials: B
authors.lastname: Gildor
authors.forename: Ben-Zion
authors.initials: BZ
authors.lastname: Shilo
authors.forename: K
authors.initials: K
authors.lastname: VijayRaghavan
authors.forename: Eyal D
authors.initials: ED
authors.lastname: Schejter
mesh_terms: D051376:Actin-Related Protein 2-3 Complex / Q000378:metabolism; D000818:Animals; D030801:Animals, Genetically Modified; D002459:Cell Fusion; D002462:Cell Membrane / Q000378:metabolism; D004330:Drosophila / Q000254:growth & development* / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism; D024510:Muscle Development / Q000502:physiology*; D009154:Mutation; D032446:Myoblasts / Q000378:metabolism / Q000502:physiology*; D034741:RNA, Small Interfering; D051316:Wiskott-Aldrich Syndrome Protein / Q000235:genetics / Q000378:metabolism*
chemical_list: D051376:Actin-Related Protein 2-3 Complex; D029721:Drosophila Proteins; D008840:Microfilament Proteins; D034741:RNA, Small Interfering; C449671:SCAR protein, Drosophila; C477859:WASp protein, Drosophila; D051316:Wiskott-Aldrich Syndrome Protein