title: An ancient role for nuclear beta-catenin in the evolution of axial polarity and germ layer segregation.
abstract: The human oncogene beta-catenin is a bifunctional protein with critical roles in both cell adhesion and transcriptional regulation in the Wnt pathway. Wnt/beta-catenin signalling has been implicated in developmental processes as diverse as elaboration of embryonic polarity, formation of germ layers, neural patterning, spindle orientation and gap junction communication, but the ancestral function of beta-catenin remains unclear. In many animal embryos, activation of beta-catenin signalling occurs in blastomeres that mark the site of gastrulation and endomesoderm formation, raising the possibility that asymmetric activation of beta-catenin signalling specified embryonic polarity and segregated germ layers in the common ancestor of bilaterally symmetrical animals. To test whether nuclear translocation of beta-catenin is involved in axial identity and/or germ layer formation in 'pre-bilaterians', we examined the in vivo distribution, stability and function of beta-catenin protein in embryos of the sea anemone Nematostella vectensis (Cnidaria, Anthozoa). Here we show that N. vectensis beta-catenin is differentially stabilized along the oral-aboral axis, translocated into nuclei in cells at the site of gastrulation and used to specify entoderm, indicating an evolutionarily ancient role for this protein in early pattern formation.
authors.affiliation: Department of Zoology, University of Hawaii at Manoa, 2538 McCarthy Mall, Honolulu 96822, Hawaii. athula@hawaii.edu
authors.forename: Athula H
authors.initials: AH
authors.lastname: Wikramanayake
authors.forename: Melanie
authors.initials: M
authors.lastname: Hong
authors.forename: Patricia N
authors.initials: PN
authors.lastname: Lee
authors.forename: Kevin
authors.initials: K
authors.lastname: Pang
authors.forename: Christine A
authors.initials: CA
authors.lastname: Byrum
authors.forename: Joanna M
authors.initials: JM
authors.lastname: Bince
authors.forename: Ronghui
authors.initials: R
authors.lastname: Xu
authors.forename: Mark Q
authors.initials: MQ
authors.lastname: Martindale
mesh_terms: D021581:Active Transport, Cell Nucleus; D000818:Animals; D037421:Anthozoa / Q000187:drug effects / Q000196:embryology* / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism*; D016764:Cell Polarity; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism*; D005775:Gastrula / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D005855:Germ Layers / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D007150:Immunohistochemistry; D018021:Lithium Chloride / Q000494:pharmacology; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D051176:beta Catenin
chemical_list: D003598:Cytoskeletal Proteins; D015534:Trans-Activators; D051176:beta Catenin; D018021:Lithium Chloride