xBtg-x regulates Wnt/beta-Catenin signaling during early Xenopus development.
In Xenopus, two signaling systems, maternal beta-Catenin and Nodal-related, are required for induction of the Spemann organizer and establishment of the body plan. By screening cDNA macroarrays for genes activated by these two signaling pathways, we identified Xenopus xBtg-x, a novel member of the Btg/Tob gene family of antiproliferative proteins. We show that xBtg-x is expressed in the dorsal mesendoderm (Spemann organizer tissue) of gastrula stage embryos and that its expression is regulated by both beta-Catenin and Nodal-related signals. Microinjection of synthetic xBtg-x mRNA into Xenopus embryos induced axis duplication and completely rescued the ventralizing effects of UV irradiation through the activation of the canonical Wnt/beta-Catenin signaling pathway. Interestingly, xBtg-x stimulated beta-Catenin-dependent transcription without affecting the stability of beta-Catenin protein. These data suggest that xBtg-x is a novel component of the Wnt/beta-Catenin signaling pathway regulating early embryonic patterning.
Howard Hughes Medical Institute, Department of Biological Chemistry, University of California, Los Angeles, CA 90095-1662, USA.
Oliver
O
Wessely
James I
JI
Kim
Uyen
U
Tran
Luis
L
Fuentealba
E M
EM
De Robertis
D000818:Animals; D002460:Cell Line; D003001:Cloning, Molecular; D003598:Cytoskeletal Proteins / Q000502:physiology*; D004625:Embryo, Nonmammalian / Q000502:physiology*; D005775:Gastrula / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental; D017930:Genes, Reporter; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000502:physiology*; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000502:physiology*; D007668:Kidney; D008648:Mesoderm / Q000502:physiology; D014176:Protein Biosynthesis; D015534:Trans-Activators / Q000502:physiology*; D014158:Transcription, Genetic; D051153:Wnt Proteins; D014981:Xenopus / Q000196:embryology / Q000254:growth & development*; D029867:Xenopus Proteins / Q000235:genetics / Q000502:physiology*; D051176:beta Catenin
C495266:CTNNB1 protein, Xenopus; C495270:CTNNB1 protein, human; D003598:Cytoskeletal Proteins; D036341:Intercellular Signaling Peptides and Proteins; D047908:Intracellular Signaling Peptides and Proteins; D015534:Trans-Activators; D051153:Wnt Proteins; D029867:Xenopus Proteins; D051176:beta Catenin; C503416:btg5.3 protein, Xenopus