A role for maternal beta-catenin in early mesoderm induction in Xenopus.
Mesoderm formation results from an inducing process that requires maternal and zygotic FGF/MAPK and TGFbeta activities, while maternal activation of the Wnt/beta-catenin pathway determines the anterior-dorsal axis. Here, we show a new role of Wnt/beta-catenin signaling in mesoderm induction. We find that maternal beta-catenin signaling is not only active dorsally but also all around the equatorial region, coinciding with the prospective mesoderm. Maternal beta-catenin function is required both for expression of dorsal genes and for activation of MAPK and the mesodermal markers Xbra and eomesodermin. beta-catenin acts in a non- cell-autonomous manner upstream of zygotic FGF and nodal signals. The Wnt/beta-catenin activity in the equatorial region of the early embryo is the first example of a maternally provided mesoderm inducer restricted to the prospective mesoderm.
Schohl
Anne
A
Department of Cell Biology, Max-Planck Institute for Developmental Biology, Tübingen, Germany.
Fagotto
François
F
D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D017931:DNA Primers; D004627:Embryonic Induction; D004789:Enzyme Activation; D005260:Female; D005346:Fibroblast Growth Factors / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D018392:Genomic Imprinting; D008648:Mesoderm; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D014981:Xenopus; D029867:Xenopus Proteins; D051176:beta Catenin
C495266:CTNNB1 protein, Xenopus; D003598:Cytoskeletal Proteins; D017931:DNA Primers; D015534:Trans-Activators; D029867:Xenopus Proteins; D051176:beta Catenin; D005346:Fibroblast Growth Factors; D020928:Mitogen-Activated Protein Kinases