title: Frizzled-7 signalling controls tissue separation during Xenopus gastrulation.
abstract: Cell signalling through Frizzled receptors has evolved to considerable complexity within the metazoans. The Frizzled-dependent signalling cascade comprises several branches, whose differential activation depends on specific Wnt ligands, Frizzled receptor isoforms and the cellular context. In Xenopus laevis embryos, the canonical beta-catenin pathway contributes to the establishment of the dorsal-ventral axis. A different branch, referred to as the planar cell polarity pathway, is essential for cell polarization during elongation of the axial mesoderm by convergent extension. Here we demonstrate that a third branch of the cascade is independent of Dishevelled function and involves signalling through trimeric G proteins and protein kinase C (PKC). During gastrulation, Frizzled-7 (Fz7)-dependent PKC signalling controls cell-sorting behaviour in the mesoderm. Loss of zygotic Fz7 function results in the inability of involuted anterior mesoderm to separate from the ectoderm, which leads to severe gastrulation defects. This result provides a developmentally relevant in vivo function for the Fz/PKC pathway in vertebrates.
authors.affiliation: Max-Planck-Institute for Developmental Biology, Department of Cell Biology, Spemann Strasse 35, D-72076 Tübingen, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Winklbauer
authors.forename: A
authors.initials: A
authors.lastname: Medina
authors.forename: R K
authors.initials: RK
authors.lastname: Swain
authors.forename: H
authors.initials: H
authors.lastname: Steinbeisser
mesh_terms: D000818:Animals; D016764:Cell Polarity; D003598:Cytoskeletal Proteins / Q000378:metabolism; D004625:Embryo, Nonmammalian; D005346:Fibroblast Growth Factors / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000378:metabolism; D005775:Gastrula / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D015870:Gene Expression / Q000187:drug effects; D008648:Mesoderm / Q000502:physiology; D009024:Morphogenesis / Q000502:physiology; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D043562:Receptors, G-Protein-Coupled; D015398:Signal Transduction; D015534:Trans-Activators; D029867:Xenopus Proteins; D014982:Xenopus laevis; D051176:beta Catenin
chemical_list: C495266:CTNNB1 protein, Xenopus; D003598:Cytoskeletal Proteins; C492040:Fzd7 protein, Xenopus; D016376:Oligonucleotides, Antisense; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; D015534:Trans-Activators; D029867:Xenopus Proteins; D051176:beta Catenin; D005346:Fibroblast Growth Factors; D011493:Protein Kinase C; D019204:GTP-Binding Proteins