title: An invasive podosome-like structure promotes fusion pore formation during myoblast fusion.
abstract: Recent studies in Drosophila have implicated actin cytoskeletal remodeling in myoblast fusion, but the cellular mechanisms underlying this process remain poorly understood. Here we show that actin polymerization occurs in an asymmetric and cell type-specific manner between a muscle founder cell and a fusion-competent myoblast (FCM). In the FCM, a dense F-actin-enriched focus forms at the site of fusion, whereas a thin sheath of F-actin is induced along the apposing founder cell membrane. The FCM-specific actin focus invades the apposing founder cell with multiple finger-like protrusions, leading to the formation of a single-channel macro fusion pore between the two muscle cells. Two actin nucleation-promoting factors of the Arp2/3 complex, WASP and Scar, are required for the formation of the F-actin foci, whereas WASP but not Scar promotes efficient foci invasion. Our studies uncover a novel invasive podosome-like structure (PLS) in a developing tissue and reveal a previously unrecognized function of PLSs in facilitating cell membrane juxtaposition and fusion.
authors.affiliation: Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
authors.forename: Kristin L
authors.initials: KL
authors.lastname: Sens
authors.forename: Shiliang
authors.initials: S
authors.lastname: Zhang
authors.forename: Peng
authors.initials: P
authors.lastname: Jin
authors.forename: Rui
authors.initials: R
authors.lastname: Duan
authors.forename: Guofeng
authors.initials: G
authors.lastname: Zhang
authors.forename: Fengbao
authors.initials: F
authors.lastname: Luo
authors.forename: Lauren
authors.initials: L
authors.lastname: Parachini
authors.forename: Elizabeth H
authors.initials: EH
authors.lastname: Chen
mesh_terms: D051376:Actin-Related Protein 2-3 Complex / Q000378:metabolism; D000199:Actins / Q000378:metabolism; D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D022081:Cell Surface Extensions / Q000378:metabolism / Q000648:ultrastructure*; D004330:Drosophila / Q000378:metabolism / Q000648:ultrastructure*; D029721:Drosophila Proteins / Q000378:metabolism; D008561:Membrane Fusion / Q000502:physiology*; D008840:Microfilament Proteins / Q000378:metabolism; D032446:Myoblasts / Q000378:metabolism / Q000648:ultrastructure*; D051316:Wiskott-Aldrich Syndrome Protein / Q000378:metabolism
chemical_list: D051376:Actin-Related Protein 2-3 Complex; D000199:Actins; D029721:Drosophila Proteins; D008840:Microfilament Proteins; C449671:SCAR protein, Drosophila; D051316:Wiskott-Aldrich Syndrome Protein