title: WNT signalling molecules act in axis formation in the diploblastic metazoan Hydra.
abstract: Members of the Wnt/wingless family of secreted proteins act as short-range inducers and long-range organizers during axis formation, organogenesis and tumorigenesis in many developing tissues. Wnt signalling pathways are conserved in nematodes, insects and vertebrates. Despite its developmental significance, the evolutionary origin of Wnt signalling is unclear. Here we describe the molecular characterization of members of the Wnt signalling pathway--Wnt, Dishevelled, GSK3, beta-Catenin and Tcf/Lef--in Hydra, a member of the evolutionarily old metazoan phylum Cnidaria. Wnt and Tcf are expressed in the putative Hydra head organizer, the upper part of the hypostome. Wnt, beta-Catenin and Tcf are transcriptionally upregulated when head organizers are established early in bud formation and head regeneration. Wnt and Tcf expression domains also define head organizers created by de novo pattern formation in aggregates. Our results indicate that Wnt signalling may be involved in axis formation in Hydra and support the idea that it was central in the evolution of axial differentiation in early multicellular animals.
authors.affiliation: Department of Molecular Cell Biology, Zoological Institute, Darmstadt University of Technology, Germany. hobmayer@bio.tu-darmstadt.de
authors.forename: B
authors.initials: B
authors.lastname: Hobmayer
authors.forename: F
authors.initials: F
authors.lastname: Rentzsch
authors.forename: K
authors.initials: K
authors.lastname: Kuhn
authors.forename: C M
authors.initials: CM
authors.lastname: Happel
authors.forename: C C
authors.initials: CC
authors.lastname: von Laue
authors.forename: P
authors.initials: P
authors.lastname: Snyder
authors.forename: U
authors.initials: U
authors.lastname: Rothbächer
authors.forename: T W
authors.initials: TW
authors.lastname: Holstein
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D019521:Body Patterning / Q000502:physiology; D003598:Cytoskeletal Proteins / Q000378:metabolism; D000072261:Dishevelled Proteins; D006829:Hydra / Q000196:embryology / Q000378:metabolism; D008969:Molecular Sequence Data; D020897:Organizers, Embryonic; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism; D016133:Polymerase Chain Reaction; D011506:Proteins / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D015534:Trans-Activators; D051153:Wnt Proteins; D029961:Zebrafish Proteins; D051176:beta Catenin
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D003598:Cytoskeletal Proteins; D000072261:Dishevelled Proteins; D010750:Phosphoproteins; D011506:Proteins; D011518:Proto-Oncogene Proteins; D015534:Trans-Activators; D051153:Wnt Proteins; D029961:Zebrafish Proteins; D051176:beta Catenin