title: Zebrafish wnt8 and wnt8b share a common activity but are involved in distinct developmental pathways.
abstract: The specification of the vertebrate body plan is dependent on numerous signaling molecules, including members of the Wnt family. We have identified two zebrafish wnt8 paralogs related to Xwnt-8B and Xwnt-8, respectively. A RT-PCR assay demonstrated that wnt8 is expressed maternally, with transcripts detected throughout embryogenesis, whereas wnt8b transcripts were first detected during late gastrulation. The wnt8 transcripts at 50% epiboly are spatially restricted to those cells at the blastoderm margin, overlying gsc-expressing cells in the axial hypoblast. During late gastrulation, wnt8 was no longer detected in the marginal cells at the dorsal midline and by mid-segmentation, transcripts were found in the presumptive tail bud. In contrast, wnt8b expression is spatially restricted to prospective neuroepithelium, and later to neural-specific structures. Overexpression of both wnts results in two major phenotypes: radialized embryos and embryos with anterior defects. These phenotypes were preceded by significant changes in the spatial expression patterns of gsc and ntl transcripts, reminiscent of activities of Xwnt-8 in Xenopus, and consistent with a role for wnt8 in the specification or patterning of mesoderm.
authors.affiliation: Howard Hughes Medical Institute, Department of Pharmacology, Seattle, Washington, USA.
authors.forename: G M
authors.initials: GM
authors.lastname: Kelly
authors.forename: P
authors.initials: P
authors.lastname: Greenstein
authors.forename: D F
authors.initials: DF
authors.lastname: Erezyilmaz
authors.forename: R T
authors.initials: RT
authors.lastname: Moon
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003598:Cytoskeletal Proteins; D017931:DNA Primers; D004627:Embryonic Induction / Q000235:genetics*; D005260:Female; D015870:Gene Expression; D017403:In Situ Hybridization; D008648:Mesoderm / Q000502:physiology*; D008969:Molecular Sequence Data; D009024:Morphogenesis; D010641:Phenotype; D016133:Polymerase Chain Reaction; D011506:Proteins / Q000235:genetics*; D016415:Sequence Alignment; D051153:Wnt Proteins; D014981:Xenopus; D015027:Zebrafish / Q000196:embryology / Q000235:genetics*; D029961:Zebrafish Proteins
chemical_list: D003598:Cytoskeletal Proteins; D017931:DNA Primers; D011506:Proteins; D051153:Wnt Proteins; D029961:Zebrafish Proteins; C094521:wnt8a protein, zebrafish; C094522:wnt8b protein, zebrafish