title: Myosin heavy chain-like localizes at cell contact sites during Drosophila myoblast fusion and interacts in vitro with Rolling pebbles 7.
abstract: Besides representing the sarcomeric thick filaments, myosins are involved in many cellular transport and motility processes. Myosin heavy chains are grouped into 18 classes. Here we show that in Drosophila, the unconventional group XVIII myosin heavy chain-like (Mhcl) is transcribed in the mesoderm of embryos, most prominently in founder cells (FCs). An ectopically expressed GFP-tagged Mhcl localizes in the growing muscle at cell-cell contacts towards the attached fusion competent myoblast (FCM). We further show that Mhcl interacts in vitro with the essential fusion protein Rolling pebbles 7 (Rols7), which is part of a protein complex established at cell contact sites (Fusion-restricted Myogenic-Adhesive Structure or FuRMAS). Here, branched F-actin is likely needed to widen the fusion pore and to integrate the myoblast into the growing muscle. We show that the localization of Mhcl is dependent on the presence of Rols7, and we postulate that Mhcl acts at the FuRMAS as an actin motor protein. We further show that Mhcl deficient embryos develop a wild-type musculature. We thus propose that Mhcl functions redundantly to other myosin heavy chains in myoblasts. Lastly, we found that the protein is detectable adjacent to the sarcomeric Z-discs, suggesting an additional function in mature muscles.
authors.affiliation: Developmental Biology, Department of Biology, Philipps-Universität Marburg, Karl-von-Frisch-Strasse 8, 35037 Marburg, Germany.
authors.forename: Bettina R
authors.initials: BR
authors.lastname: Bonn
authors.forename: Anja
authors.initials: A
authors.lastname: Rudolf
authors.forename: Christina
authors.initials: C
authors.lastname: Hornbruch-Freitag
authors.forename: Gabor
authors.initials: G
authors.lastname: Daum
authors.forename: Jessica
authors.initials: J
authors.lastname: Kuckwa
authors.forename: Lena
authors.initials: L
authors.lastname: Kastl
authors.forename: Detlev
authors.initials: D
authors.lastname: Buttgereit
authors.forename: Renate
authors.initials: R
authors.lastname: Renkawitz-Pohl
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D002448:Cell Adhesion / Q000235:genetics; D002450:Cell Communication / Q000235:genetics / Q000502:physiology; D002459:Cell Fusion; D002478:Cells, Cultured; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D004331:Drosophila melanogaster / Q000196:embryology / Q000235:genetics / Q000378:metabolism; D004625:Embryo, Nonmammalian; D018507:Gene Expression Regulation, Developmental; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D024510:Muscle Development / Q000235:genetics / Q000502:physiology; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D032446:Myoblasts / Q000378:metabolism / Q000502:physiology*; D009218:Myosins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding / Q000235:genetics; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D021381:Protein Transport; D014018:Tissue Distribution
chemical_list: D029721:Drosophila Proteins; D008565:Membrane Proteins; D009124:Muscle Proteins; D020033:Protein Isoforms; C560638:myosin-18, Drosophila; C443104:rols protein, Drosophila; D009218:Myosins