Beta-catenin translocation into nuclei demarcates the dorsalizing centers in frog and fish embryos.
The question of how dorsal-ventral polarity is established in vertebrates is central to our understanding of their early development. Several lines of evidence suggest that wnt-signaling is involved in the induction of dorsal-specific gene expression in the Spemann Organizer of amphibians. Here, we show that beta-catenin, acting as a component of the wnt-pathway, transiently accumulates in nuclei on the dorsal side of Xenopus and zebrafish blastulae. The spatially restricted nuclear translocation of beta-catenin precedes the expression of dorsal-specific genes. In experimentally ventralized frog embryos the dorsal ventral pattern of beta-catenin nuclear staining is abolished; in contrast, embryos hyperdorsalized by Li-ions or by injection of Xwnt8 mRNA exhibit an enhanced nuclear accumulation of beta-catenin. The results show that translocation of beta-catenin into nuclei in the wake of wnt-signaling is an early step in the establishment of the dorsal-ventral axis in frog and fish embryos.
Schneider
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S
Abteilung V (Zellbiologie), Max-Planck-Institut für Entwicklungsbiologie, Tübingen, Germany.
Steinbeisser
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H
Warga
R M
RM
Hausen
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P
D000818:Animals; D019521:Body Patterning / Q000502:physiology*; D015820:Cadherins / Q000378:metabolism*; D002467:Cell Nucleus / Q000737:chemistry / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000235:genetics* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental / Q000502:physiology; D008094:Lithium / Q000494:pharmacology; D015534:Trans-Activators; D014981:Xenopus / Q000196:embryology*; D029867:Xenopus Proteins; D015027:Zebrafish / Q000196:embryology*; D029961:Zebrafish Proteins; D051176:beta Catenin
C495266:CTNNB1 protein, Xenopus; D015820:Cadherins; D003598:Cytoskeletal Proteins; D015534:Trans-Activators; D029867:Xenopus Proteins; D029961:Zebrafish Proteins; D051176:beta Catenin; C495269:ctnnb1 protein, zebrafish; D008094:Lithium