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Development Genes and Evolution

, Volume 209, Issue 1, pp 48–58 | Cite as

Conservation of intracellular Wnt signaling components in dorsal-ventral axis formation in zebrafish

  • L. Sumoy
  • Julie Kiefer
  • D. Kimelman
ORIGINAL ARTICLE

Abstract

 The mechanism of early dorso-ventral axis specification in zebrafish embryos is not well understood. While β-catenin has been clearly implicated as a determinant of the axis, the factors upstream and downstream of β-catenin in this system are not defined. Unlike in Xenopus, where a sperm-induced cortical rotation is used to localize β-catenin on the future dorsal side of the embryo, zebrafish do not have an obviously similar morphogenetic movement. Recently, a GSK-3 (Glycogen Synthase Kinase-3) binding protein (GBP) was identified as a novel member of the Wnt pathway required for maternal dorsal axis formation in Xenopus. GBP stabilizes β-catenin levels by inhibiting GSK-3 and potentially provides a link between cortical rotation and β-catenin regulation. Since zebrafish may use a different mechanism for regulating β-catenin, we asked whether zebrafish also express a maternal GBP. We report the isolation of the zebrafish GBP gene and show that it is maternally expressed and is present as mRNA ubiquitously throughout early embryonic development. Over-expression of zebrafish GBP in frogs and fish leads to hyper-dorsalized phenotypes, similar to the effects resulting from over-expression of β-catenin, indicating that components upstream of β-catenin are conserved between amphibians and teleosts. We also examined whether Tcf (T cell factor) functions in zebrafish embryos. As in frogs, ectopic expression of a dominant negative form of XTcf-3 ventralizes zebrafish embryos. In addition, ectopic β-catenin expression activates the promoter of the Tcf-dependent gene siamois, indicating that the step immediately downstream of β-catenin is also conserved between fish and frogs.

Key words Glycogen synthase kinase-3 binding protein Dorso-ventral axis Zebrafish Wnt signaling T cell factor 

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Copyright information

© Springer-Verlag Berlin Heidelberg 1999

Authors and Affiliations

  • L. Sumoy
    • 1
  • Julie Kiefer
    • 1
  • D. Kimelman
    • 1
  1. 1.Department of Biochemistry, Box 357350, University of Washington, Seattle, WA 98195-7350, USAUS

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