Wnt signaling promotes oral but suppresses aboral structures in Hydractinia metamorphosis and regeneration.
We studied the role of Wnt signaling in axis formation during metamorphosis and regeneration in the cnidarian Hydractinia. Activation of Wnt downstream events during metamorphosis resulted in a complete oralization of the animals and repression of aboral structures (i.e. stolons). The expression of Wnt3, Tcf and Brachyury was upregulated and became ubiquitous. Rescue experiments using Tcf RNAi resulted in normal metamorphosis and quantitatively normal Wnt3 and Brachyury expression. Isolated, decapitated polyps regenerated only heads but no stolons. Activation of Wnt downstream targets in regenerating animals resulted in oralization of the polyps. Knocking down Tcf or Wnt3 by RNAi inhibited head regeneration and resulted in complex phenotypes that included ectopic aboral structures. Multiple heads then grew when the RNAi effect had dissipated. Our results provide functional evidence that Wnt promotes head formation but represses the formation of stolons, whereas downregulation of Wnt promotes stolons and represses head formation.
Duffy
David J
DJ
School of Natural Sciences and Martin Ryan Marine Science Institute, National University of Ireland, Galway, Galway, Ireland.
Plickert
Günter
G
Kuenzel
Timo
T
Tilmann
Wido
W
Frank
Uri
U
D000818:Animals; D005326:Fetal Proteins / Q000235:genetics / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D037402:Hydrozoa / Q000033:anatomy & histology / Q000196:embryology / Q000502:physiology*; D008675:Metamorphosis, Biological; D012038:Regeneration; D015398:Signal Transduction; D020825:T-Box Domain Proteins / Q000235:genetics / Q000378:metabolism; D051820:TCF Transcription Factors / Q000235:genetics / Q000378:metabolism; D051153:Wnt Proteins / Q000235:genetics / Q000378:metabolism*; D051176:beta Catenin; D000098908:Brachyury Protein
D005326:Fetal Proteins; D020825:T-Box Domain Proteins; D051820:TCF Transcription Factors; D051153:Wnt Proteins; D051176:beta Catenin; D000098908:Brachyury Protein