title: Tcf- and Vent-binding sites regulate neural-specific geminin expression in the gastrula embryo.
abstract: Vertebrate neural development has been extensively investigated. However, it is unknown for any vertebrate gene how the onset of neural-specific expression in early gastrula embryos is transcriptionally regulated. geminin expression is among the earliest markers of dorsal, prospective neurectoderm at early gastrulation in Xenopus laevis. Here, we identified two 5' sequence domains that are necessary and sufficient to drive neural-specific expression during gastrulation in transgenic Xenopus embryos. Each domain contained putative binding sites for the transcription factor Tcf, which can mediate Wnt signaling and for Vent homeodomain proteins, transcriptional repressors that mediate BMP signaling. Results from embryos transgenic for constructs with mutated Tcf or Vent sites demonstrated that signaling through the Tcf sites was required for dorsal-specific expression at early gastrulation, while signaling through the Vent sites restricted geminin expression to the prospective neurectoderm at mid-gastrulation. Consistent with these results, geminin 5' regulatory sequences and endogenous Xgem responded positively to Wnt signaling and negatively to BMP signaling. The two 5' sequence domains were also conserved among geminin orthologs. Together, these results demonstrate that signaling through Tcf and Vent binding sites regulates transcription of geminin in prospective neurectoderm during gastrulation.
authors.affiliation: Department of Molecular Biology and Pharmacology, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110, USA.
authors.forename: Jennifer J
authors.initials: JJ
authors.lastname: Taylor
authors.forename: Ting
authors.initials: T
authors.lastname: Wang
authors.forename: Kristen L
authors.initials: KL
authors.lastname: Kroll
mesh_terms: D000818:Animals; D001665:Binding Sites / Q000235:genetics; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D017124:Conserved Sequence; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000378:metabolism; D019143:Evolution, Molecular; D005775:Gastrula / Q000166:cytology / Q000378:metabolism*; D064248:Geminin; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D017403:In Situ Hybridization; D008957:Models, Genetic; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D050436:Regulatory Elements, Transcriptional; D015398:Signal Transduction; D051820:TCF Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic; D019076:Transgenes; D051155:Wnt1 Protein / Q000235:genetics / Q000378:metabolism; D014981:Xenopus / Q000196:embryology* / Q000235:genetics / Q000378:metabolism; D029867:Xenopus Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D018797:Cell Cycle Proteins; C577998:GMNN protein, Xenopus; D064248:Geminin; D018398:Homeodomain Proteins; D051820:TCF Transcription Factors; D014157:Transcription Factors; C495249:WNT1 protein, Xenopus; D051155:Wnt1 Protein; D029867:Xenopus Proteins; C099992:ventx2.1 protein, Xenopus