Analysis of the Tcf-3 promoter during early development of Xenopus.
XTcf-3 functions as a transcriptional regulator in the canonical Wnt signaling cascade and can repress or activate downstream target genes. Expression of XTcf-3 is differentially regulated in time and place during development (Molenaar et al. [1998] Mech Dev. 75:151-154), but little is known about the mechanisms that control transcriptional activation and repression. A 15-kb genomic fragment of Tcf-3 sequences from Xenopus tropicalis was cloned, including the 5' untranslated region; exons 1, 2, and 3; and intron sequences. We used 5' deletion constructs for transgenesis and episomal luciferase assays in Xenopus to examine temporal and spatial regulation of the promoter during early development. A -3054/+34-bp Tcf-3 upstream region was identified that drives a green fluorescent protein (GFP) reporter transgene in a pattern similar to endogenous expression of XtTcf-3 from gastrula to tail bud stages. At stage 12, expression of the reporter is restricted to the middle and posterior neurectoderm. At stage 22, expression is strongest in the neural plate, the eye anlagen and branchial arches. At stage 35/36, expression is found in the head mesenchyme, the branchial arches, the heart, the mesencephalon, eyes, otic vesicles, notochord, somites and the lateral plate mesoderm. Part of the cis-acting elements driving this GFP reporter transgene expression map between -372 and -95 bp of the transcription start site. Furthermore, two TCF/LEF sites are necessary for full activity of the promoter during gastrula stages in episomal luciferase assays.
Spieker
Nicole
N
Hubrecht Laboratory, Netherlands Institute for Developmental Biology, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands.
Peterson
Josi
J
Reneman
Stefan
S
Destrée
Olivier
O
D020121:5' Untranslated Regions; D000818:Animals; D030801:Animals, Genetically Modified; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D004252:DNA Mutational Analysis; D004625:Embryo, Nonmammalian; D047108:Embryonic Development; D005091:Exons; D005775:Gastrula; D017353:Gene Deletion; D018507:Gene Expression Regulation, Developmental; D017930:Genes, Reporter; D016678:Genome; D049452:Green Fluorescent Proteins / Q000378:metabolism; D017403:In Situ Hybridization; D007438:Introns; D008156:Luciferases / Q000378:metabolism; D009865:Oocytes / Q000378:metabolism; D011401:Promoter Regions, Genetic; D013997:Time Factors; D014018:Tissue Distribution / Q000235:genetics; D015534:Trans-Activators; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D019076:Transgenes; D014981:Xenopus / Q000196:embryology* / Q000235:genetics / Q000378:metabolism
D020121:5' Untranslated Regions; D015534:Trans-Activators; D014157:Transcription Factors; D049452:Green Fluorescent Proteins; D008156:Luciferases