title: Dynamic myosin phosphorylation regulates contractile pulses and tissue integrity during epithelial morphogenesis.
abstract: Apical constriction is a cell shape change that promotes epithelial bending. Activation of nonmuscle myosin II (Myo-II) by kinases such as Rho-associated kinase (Rok) is important to generate contractile force during apical constriction. Cycles of Myo-II assembly and disassembly, or pulses, are associated with apical constriction during Drosophila melanogaster gastrulation. It is not understood whether Myo-II phosphoregulation organizes contractile pulses or whether pulses are important for tissue morphogenesis. Here, we show that Myo-II pulses are associated with pulses of apical Rok. Mutants that mimic Myo-II light chain phosphorylation or depletion of myosin phosphatase inhibit Myo-II contractile pulses, disrupting both actomyosin coalescence into apical foci and cycles of Myo-II assembly/disassembly. Thus, coupling dynamic Myo-II phosphorylation to upstream signals organizes contractile Myo-II pulses in both space and time. Mutants that mimic Myo-II phosphorylation undergo continuous, rather than incremental, apical constriction. These mutants fail to maintain intercellular actomyosin network connections during tissue invagination, suggesting that Myo-II pulses are required for tissue integrity during morphogenesis.
authors.affiliation: Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142.
authors.forename: Claudia G
authors.initials: CG
authors.lastname: Vasquez
authors.affiliation: Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142.
authors.forename: Mike
authors.initials: M
authors.lastname: Tworoger
authors.affiliation: Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142 acmartin@mit.edu.
authors.forename: Adam C
authors.initials: AC
authors.lastname: Martin
mesh_terms: D000205:Actomyosin / Q000378:metabolism; D000818:Animals; D016764:Cell Polarity; D029721:Drosophila Proteins / Q000378:metabolism; D004331:Drosophila melanogaster / Q000166:cytology / Q000196:embryology* / Q000201:enzymology; D004848:Epithelium / Q000196:embryology / Q000201:enzymology; D009024:Morphogenesis; D018994:Myosin Light Chains / Q000378:metabolism; D024462:Myosin Type II / Q000378:metabolism*; D043263:Myosin-Light-Chain Phosphatase / Q000378:metabolism; D010766:Phosphorylation; D055503:Protein Multimerization; D011499:Protein Processing, Post-Translational; D059008:Time-Lapse Imaging; D054460:rho-Associated Kinases / Q000378:metabolism
chemical_list: D029721:Drosophila Proteins; D018994:Myosin Light Chains; C495593:Sqh protein, Drosophila; D000205:Actomyosin; D054460:rho-Associated Kinases; D043263:Myosin-Light-Chain Phosphatase; D024462:Myosin Type II
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