title: Dynamic analysis of actin cable function during Drosophila dorsal closure.
abstract: Throughout development, a series of epithelial movements and fusions occur that collectively shape the embryo. They are dependent on coordinated reorganizations and contractions of the actin cytoskeleton within defined populations of epithelial cells. One paradigm morphogenetic movement, dorsal closure in the Drosophila embryo, involves closure of a dorsal epithelial hole by sweeping of epithelium from the two sides of the embryo over the exposed extraembryonic amnioserosa to form a seam where the two epithelial edges fuse together. The front row cells exhibit a thick actin cable at their leading edge. Here, we test the function of this cable by live analysis of GFP-actin-expressing embryos in which the cable is disrupted by modulating Rho1 signaling or by loss of non-muscle myosin (Zipper) function. We show that the cable serves a dual role during dorsal closure. It is contractile and thus can operate as a "purse string," but it also restricts forward movement of the leading edge and excess activity of filopodia/lamellipodia. Stripes of epithelium in which cable assembly is disrupted gain a migrational advantage over their wild-type neighbors, suggesting that the cable acts to restrain front row cells, thus maintaining a taut, free edge for efficient zippering together of the epithelial sheets.
authors.affiliation: Department of Anatomy andDevelopmental Biology, University College London, United Kingdom. ajacinto@igc.gulbenkian.pt
authors.forename: Antonio
authors.initials: A
authors.lastname: Jacinto
authors.forename: William
authors.initials: W
authors.lastname: Wood
authors.forename: Sarah
authors.initials: S
authors.lastname: Woolner
authors.forename: Charlotte
authors.initials: C
authors.lastname: Hiley
authors.forename: Laura
authors.initials: L
authors.lastname: Turner
authors.forename: Clive
authors.initials: C
authors.lastname: Wilson
authors.forename: Alfonso
authors.initials: A
authors.lastname: Martinez-Arias
authors.forename: Paul
authors.initials: P
authors.lastname: Martin
mesh_terms: D000199:Actins / Q000502:physiology*; D000818:Animals; D004330:Drosophila / Q000196:embryology*; D004625:Embryo, Nonmammalian / Q000648:ultrastructure; D047108:Embryonic Development; D008855:Microscopy, Electron, Scanning
chemical_list: D000199:Actins