title: Lef/Tcf-dependent Wnt/beta-catenin signaling during Xenopus axis specification.
abstract: Though the Wnt/beta-catenin signaling pathway is known to play key roles during Xenopus axis specification, whether it signals exclusively through Lef/Tcf transcription factors in this process remains unclear. To investigate this issue, we generated transgenic frog embryos expressing green fluorescent protein (GFP) driven by a Lef/Tcf-dependent and Wnt/beta-catenin-responsive promoter. This promoter is highly sensitive and even detects maternal beta-catenin activity prior to the large-scale transcription of zygotic genes. Unexpectedly, GFP expression was observed only in some, but not all, known Wnt/beta-catenin-positive territories in Xenopus early development. Furthermore, ubiquitous expression of dominant Lef-1 protein variants from transgenes revealed that zygotic Lef/Tcf activity is required for the ventroposterior development of Xenopus embryos. In summary, our results suggest that endogenous Wnt/beta-catenin activity does not result in obligatory Lef/Tcf-dependent gene activation, and that the ventroposteriorizing activity of zygotic Wnt-8 signaling is mediated by Lef/Tcf proteins.
authors.affiliation: Laboratory of Molecular and Cell Biology, Laboratory of Stem Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Yue-yang Road 320, 200031, Shanghai, PR China
authors.forename: Xin
authors.initials: X
authors.lastname: Geng
authors.forename: Lei
authors.initials: L
authors.lastname: Xiao
authors.forename: Gu Fa
authors.initials: GF
authors.lastname: Lin
authors.forename: Ruiying
authors.initials: R
authors.lastname: Hu
authors.forename: Jin Hu
authors.initials: JH
authors.lastname: Wang
authors.forename: Ralph A W
authors.initials: RA
authors.lastname: Rupp
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Ding
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D019521:Body Patterning / Q000235:genetics*; D015820:Cadherins / Q000235:genetics; D003598:Cytoskeletal Proteins / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics*; D004625:Embryo, Nonmammalian / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D017930:Genes, Reporter; D016762:Genes, fos; D049452:Green Fluorescent Proteins; D024002:HMGB Proteins / Q000235:genetics*; D006609:High Mobility Group Proteins / Q000235:genetics*; D016350:Leucine Zippers; D008156:Luciferases / Q000235:genetics; D008164:Luminescent Proteins / Q000235:genetics; D051821:Lymphoid Enhancer-Binding Factor 1; D051265:NF-E2-Related Factor 1; D011505:Protein-Tyrosine Kinases / Q000235:genetics; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D015398:Signal Transduction; D051820:TCF Transcription Factors; D015534:Trans-Activators / Q000235:genetics*; D058125:Transcription Factor 7-Like 1 Protein; D058118:Transcription Factor 7-Like 2 Protein; D014157:Transcription Factors / Q000235:genetics*; D015533:Transcriptional Activation; D051153:Wnt Proteins; D014981:Xenopus / Q000196:embryology* / Q000235:genetics*; D029867:Xenopus Proteins / Q000235:genetics; D029961:Zebrafish Proteins; D015053:Zygote / Q000502:physiology; D051176:beta Catenin
chemical_list: C495266:CTNNB1 protein, Xenopus; D015820:Cadherins; D003598:Cytoskeletal Proteins; D004268:DNA-Binding Proteins; D024002:HMGB Proteins; D006609:High Mobility Group Proteins; C116548:Lef1 protein, Xenopus; D008164:Luminescent Proteins; D051821:Lymphoid Enhancer-Binding Factor 1; D051265:NF-E2-Related Factor 1; C088357:NFE2L1 protein, human; D011518:Proto-Oncogene Proteins; D051820:TCF Transcription Factors; C544912:TCF7L1 protein, human; C544894:TCF7L2 protein, human; D015534:Trans-Activators; D058125:Transcription Factor 7-Like 1 Protein; D058118:Transcription Factor 7-Like 2 Protein; D014157:Transcription Factors; D051153:Wnt Proteins; D029867:Xenopus Proteins; D029961:Zebrafish Proteins; D051176:beta Catenin; C544896:tcf7l2 protein, Xenopus; C495248:wnt8a protein, Xenopus; D049452:Green Fluorescent Proteins; D008156:Luciferases; D011505:Protein-Tyrosine Kinases