Blocking Dishevelled signaling in the noncanonical Wnt pathway in sea urchins disrupts endoderm formation and spiculogenesis, but not secondary mesoderm formation

Dev Dyn. 2009 Jul;238(7):1649-65. doi: 10.1002/dvdy.21978.

Abstract

Dishevelled (Dsh) is a phosphoprotein key to beta-catenin dependent (canonical) and beta-catenin independent (noncanonical) Wnt signaling. Whereas canonical Wnt signaling has been intensively studied in sea urchin development, little is known about other Wnt pathways. To examine roles of these beta-catenin independent pathways in embryogenesis, we used Dsh-DEP, a deletion construct blocking planar cell polarity (PCP) and Wnt/Ca(2+) signaling. Embryos overexpressing Dsh-DEP failed to gastrulate or undergo skeletogenesis, but produced pigment cells. Although early mesodermal gene expression was largely unperturbed, embryos exhibited reduced expression of genes regulating endoderm specification and differentiation. Overexpressing activated beta-catenin failed to rescue Dsh-DEP embryos, indicating that Dsh-DEP blocks endoderm formation downstream of initial canonical Wnt signaling. Because Dsh-DEP-like constructs block PCP signaling in other metazoans, and disrupting RhoA or Fz 5/8 in echinoids blocks subsets of the Dsh-DEP phenotypes, our data suggest that noncanonical Wnt signaling is crucial for sea urchin endoderm formation and skeletogenesis.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adaptor Proteins, Signal Transducing / genetics*
  • Adaptor Proteins, Signal Transducing / metabolism
  • Animals
  • Body Patterning / genetics
  • Dishevelled Proteins
  • Embryo, Nonmammalian
  • Endoderm / embryology*
  • Endoderm / metabolism
  • Gene Deletion
  • Mesoderm / embryology*
  • Mesoderm / metabolism
  • Models, Biological
  • Phosphoproteins / genetics*
  • Phosphoproteins / metabolism
  • Pigmentation / genetics
  • Sea Urchins / embryology*
  • Sea Urchins / genetics*
  • Signal Transduction / genetics
  • Signal Transduction / physiology
  • Wnt Proteins / physiology*

Substances

  • Adaptor Proteins, Signal Transducing
  • Dishevelled Proteins
  • Phosphoproteins
  • Wnt Proteins