title: Rho GTPase and Shroom direct planar polarized actomyosin contractility during convergent extension.
abstract: Actomyosin contraction generates mechanical forces that influence cell and tissue structure. During convergent extension in Drosophila melanogaster, the spatially regulated activity of the myosin activator Rho-kinase promotes actomyosin contraction at specific planar cell boundaries to produce polarized cell rearrangement. The mechanisms that direct localized Rho-kinase activity are not well understood. We show that Rho GTPase recruits Rho-kinase to adherens junctions and is required for Rho-kinase planar polarity. Shroom, an asymmetrically localized actin- and Rho-kinase-binding protein, amplifies Rho-kinase and myosin II planar polarity and junctional localization downstream of Rho signaling. In Shroom mutants, Rho-kinase and myosin II achieve reduced levels of planar polarity, resulting in decreased junctional tension, a disruption of multicellular rosette formation, and defective convergent extension. These results indicate that Rho GTPase activity is required to establish a planar polarized actomyosin network, and the Shroom actin-binding protein enhances myosin contractility locally to generate robust mechanical forces during axis elongation.
authors.affiliation: Howard Hughes Medical Institute and 2 Developmental Biology Program, Sloan Kettering Institute, New York, NY 10065.
authors.forename: Sérgio de Matos
authors.initials: Sde M
authors.lastname: Simões
authors.forename: Avantika
authors.initials: A
authors.lastname: Mainieri
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Zallen
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism; D000205:Actomyosin / Q000235:genetics / Q000378:metabolism*; D022005:Adherens Junctions / Q000502:physiology; D000818:Animals; D030801:Animals, Genetically Modified; D015153:Blotting, Western; D016764:Cell Polarity; D049109:Cell Proliferation; D002478:Cells, Cultured; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000166:cytology* / Q000378:metabolism; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000378:metabolism; D005260:Female; D007124:Immunoenzyme Techniques; D008297:Male; D009024:Morphogenesis; D009119:Muscle Contraction / Q000502:physiology*; D024462:Myosin Type II / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic; D054460:rho-Associated Kinases / Q000235:genetics / Q000378:metabolism*
chemical_list: D003598:Cytoskeletal Proteins; D029721:Drosophila Proteins; D012333:RNA, Messenger; C575072:Shrm protein, Drosophila; D000205:Actomyosin; D054460:rho-Associated Kinases; D024462:Myosin Type II