title: Membrane extensions are associated with proper anterior migration of muscle cells during Caenorhabditis elegans embryogenesis.
abstract: C. elegans body wall muscle is formed after a series of well-orchestrated steps. With the onset of specification embryonic muscle cells accumulate under the hypodermal seam cells at the left and right sides of the embryo. Shortly thereafter they begin to migrate dorsally and ventrally resting beneath the dorsal and ventral hypodermis eventually forming the four muscle quadrants present upon hatching. In this study we describe the plasma membrane dynamics of these migrating cells and observe the extension of filopodia and lamellipodia during dorso-ventral migration but not during the earlier stages of accumulation. We also describe an anterior migration event during embryonic muscle morphogenesis, whereby the anterior-most pair of cells in each of the four muscle quadrants extends long processes to the anterior tip of the developing embryo. Anteriormost muscle cells then follow these extensions into their final positions in the developing embryo. Using RNAi and mutant analysis, we have identified laminin as being involved in mediating the dorsal-ventral muscle migrations. Finally we show that the α-integrin INA-1, the ephrin VAB-2 and its receptor VAB-1 and the Robo receptor SAX-3 indirectly promote the proper extension of the ventral anterior muscle processes by organizing the embryonic neurons so as to provide a clear path for muscle membrane extension.
authors.affiliation: Department of Zoology, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Ryan
authors.initials: R
authors.lastname: Viveiros
authors.forename: Harald
authors.initials: H
authors.lastname: Hutter
authors.forename: Donald G
authors.initials: DG
authors.lastname: Moerman
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000196:embryology*; D029742:Caenorhabditis elegans Proteins / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000378:metabolism; D002465:Cell Movement / Q000502:physiology*; D022081:Cell Surface Extensions / Q000502:physiology*; D036342:Ephrins / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D016023:Integrins / Q000378:metabolism; D007797:Laminin / Q000378:metabolism; D008856:Microscopy, Fluorescence; D009024:Morphogenesis / Q000502:physiology*; D018482:Muscle, Skeletal / Q000196:embryology*; D009419:Nerve Tissue Proteins / Q000378:metabolism; D034622:RNA Interference; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism; D011971:Receptors, Immunologic / Q000378:metabolism; D000097905:Roundabout Proteins
chemical_list: D029742:Caenorhabditis elegans Proteins; D018797:Cell Cycle Proteins; D036342:Ephrins; D049452:Green Fluorescent Proteins; D016023:Integrins; D007797:Laminin; D009419:Nerve Tissue Proteins; D020794:Receptor Protein-Tyrosine Kinases; D011971:Receptors, Immunologic; D000097905:Roundabout Proteins; C521951:Ina-1 protein, C elegans; C403283:vab-2 protein, C elegans; C111040:vab-1 protein, C elegans