title: Rho kinase activity controls directional cell movements during primitive streak formation in the rabbit embryo.
abstract: During animal gastrulation, the specification of the embryonic axes is accompanied by epithelio-mesenchymal transition (EMT), the first major change in cell shape after fertilization. EMT takes place in disparate topographical arrangements, such as the circular blastopore of amphibians, the straight primitive streak of birds and mammals or in intermediate gastrulation forms of other amniotes such as reptiles. Planar cell movements are prime candidates to arrange specific modes of gastrulation but there is no consensus view on their role in different vertebrate classes. Here, we test the impact of interfering with Rho kinase-mediated cell movements on gastrulation topography in blastocysts of the rabbit, which has a flat embryonic disc typical for most mammals. Time-lapse video microscopy, electron microscopy, gene expression and morphometric analyses of the effect of inhibiting ROCK activity showed - besides normal specification of the organizer region - a dose-dependent disruption of primitive streak formation; this disruption resulted in circular, arc-shaped or intermediate forms, reminiscent of those found in amphibians, fishes and reptiles. Our results reveal a crucial role of ROCK-controlled directional cell movements during rabbit primitive streak formation and highlight the possibility that temporal and spatial modulation of cell movements were instrumental for the evolution of gastrulation forms.
authors.affiliation: Institute of Anatomy and Embryology, University Medical Centre, Georg August University of Göttingen, Göttingen 37079, Germany.
authors.forename: Viktoria
authors.initials: V
authors.lastname: Stankova
authors.affiliation: Institute of Anatomy and Embryology, University Medical Centre, Georg August University of Göttingen, Göttingen 37079, Germany.
authors.forename: Nikoloz
authors.initials: N
authors.lastname: Tsikolia
authors.affiliation: Institute of Anatomy and Embryology, University Medical Centre, Georg August University of Göttingen, Göttingen 37079, Germany christoph.viebahn@medizin.uni-goettingen.de.
authors.forename: Christoph
authors.initials: C
authors.lastname: Viebahn
mesh_terms: D008841:Actin Cytoskeleton / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D005075:Biological Evolution; D019521:Body Patterning / Q000187:drug effects; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D002465:Cell Movement / Q000187:drug effects; D004622:Embryo, Mammalian / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology*; D054262:Gastrulation / Q000187:drug effects; D020897:Organizers, Embryonic / Q000166:cytology / Q000187:drug effects; D054240:Primitive Streak / Q000166:cytology* / Q000187:drug effects / Q000196:embryology* / Q000201:enzymology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011817:Rabbits; D053778:Thiazolidines / Q000494:pharmacology; D054460:rho-Associated Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D019086:Bridged Bicyclo Compounds, Heterocyclic; D047428:Protein Kinase Inhibitors; D053778:Thiazolidines; D054460:rho-Associated Kinases; C037067:latrunculin A
keywords: Amniote evolution; Cell migration; Mammalian gastrulation; Mesoderm formation; Planar cell polarity; Primitive streak