title: Rho-kinase-dependent actin turnover and actomyosin disassembly are necessary for mouse spinal neural tube closure.
abstract: The cytoskeleton is widely considered essential for neurulation, yet the mouse spinal neural tube can close despite genetic and non-genetic disruption of the cytoskeleton. To investigate this apparent contradiction, we applied cytoskeletal inhibitors to mouse embryos in culture. Preventing actomyosin cross-linking, F-actin assembly or myosin II contractile activity did not disrupt spinal closure. In contrast, inhibiting Rho kinase (ROCK, for which there are two isoforms ROCK1 and ROCK2) or blocking F-actin disassembly prevented closure, with apical F-actin accumulation and adherens junction disturbance in the neuroepithelium. Cofilin-1-null embryos yielded a similar phenotype, supporting the hypothesis that there is a key role for actin turnover. Co-exposure to Blebbistatin rescued the neurulation defects caused by RhoA inhibition, whereas an inhibitor of myosin light chain kinase, ML-7, had no such effect. We conclude that regulation of RhoA, Rho kinase, LIM kinase and cofilin signalling is necessary for spinal neural tube closure through precise control of neuroepithelial actin turnover and actomyosin disassembly. In contrast, actomyosin assembly and myosin ATPase activity are not limiting for closure.
authors.affiliation: Newlife Birth Defects Research Centre, Institute of Child Health, University College London, WC1N 1EH, UK.
authors.forename: Sarah
authors.initials: S
authors.lastname: Escuin
authors.affiliation: Newlife Birth Defects Research Centre, Institute of Child Health, University College London, WC1N 1EH, UK.
authors.forename: Bertrand
authors.initials: B
authors.lastname: Vernay
authors.affiliation: Newlife Birth Defects Research Centre, Institute of Child Health, University College London, WC1N 1EH, UK.
authors.forename: Dawn
authors.initials: D
authors.lastname: Savery
authors.affiliation: Cell Migration Unit, Institut für Genetik, Universität Bonn, 53115 Bonn, Germany.
authors.forename: Christine B
authors.initials: CB
authors.lastname: Gurniak
authors.affiliation: Cell Migration Unit, Institut für Genetik, Universität Bonn, 53115 Bonn, Germany.
authors.forename: Walter
authors.initials: W
authors.lastname: Witke
authors.affiliation: Newlife Birth Defects Research Centre, Institute of Child Health, University College London, WC1N 1EH, UK.
authors.forename: Nicholas D E
authors.initials: ND
authors.lastname: Greene
authors.affiliation: Newlife Birth Defects Research Centre, Institute of Child Health, University College London, WC1N 1EH, UK a.copp@ucl.ac.uk.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Copp
mesh_terms: D000199:Actins / Q000235:genetics / Q000378:metabolism*; D000205:Actomyosin / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D051338:Cofilin 1 / Q000235:genetics / Q000378:metabolism; D054461:Lim Kinases / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008817:Mice, Mutant Strains; D054259:Neural Tube / Q000196:embryology*; D020741:rho GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism; D054460:rho-Associated Kinases / Q000235:genetics / Q000378:metabolism*; D020742:rhoA GTP-Binding Protein
chemical_list: D000199:Actins; C495811:Cfl1 protein, mouse; D051338:Cofilin 1; D000205:Actomyosin; D054461:Lim Kinases; C515854:Rock1 protein, mouse; C515855:Rock2 protein, mouse; D054460:rho-Associated Kinases; C526380:RhoA protein, mouse; D020741:rho GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein
keywords: Cytoskeleton; Embryo; Mouse; Neurulation