Cloning and characterization of three Xenopus slug promoters reveal direct regulation by Lef/beta-catenin signaling.
In amphibians and birds, one of the first steps of neural crest cell (NCC) determination is expression of the transcription factor Slug. This marker has been used to demonstrate that BMP and Wnt molecules play a major role in NCC induction. However, it is unknown whether Slug expression is directly or indirectly regulated by these signals. We report here the cloning and characterization of three Xenopus Slug promoters: that of the Xenopus tropicalis slug gene and those of two Xenopus laevis Slug pseudoalleles. Although the three genes encode proteins with almost identical amino acid sequences and are expressed with similar spatiotemporal patterns, their 5'-flanking regions are quite different. A striking difference is a deletion in the X. tropicalis gene located precisely at the transcription initiation site that results in the X. tropicalis promoter being inefficient in X. laevis. Additionally, we identified two regions common to the three promoters that are necessary and sufficient to drive specific expression in NCCs. Interestingly, one of the common regulatory regions presents a functional Lef/beta-catenin-binding site necessary for specific expression. As the Lef.beta-catenin complex is a downstream effector of Wnt signaling, these results suggest that Xenopus Slug is a direct target of NCC determination signals.
Vallin
J
J
UMR 144, CNRS/Institut Curie, 26 rue d'Ulm, 75248 Paris Cedex 05, France. Jerome.Vallin@curie.fr
Thuret
R
R
Giacomello
E
E
Faraldo
M M
MM
Thiery
J P
JP
Broders
F
F
D000483:Alleles; D000818:Animals; D001665:Binding Sites; D003001:Cloning, Molecular; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D018076:DNA, Complementary / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D004625:Embryo, Nonmammalian / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D049452:Green Fluorescent Proteins; D017403:In Situ Hybridization; D007438:Introns; D008164:Luminescent Proteins / Q000378:metabolism; D051821:Lymphoid Enhancer-Binding Factor 1; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D015398:Signal Transduction; D000071250:Snail Family Transcription Factors; D015534:Trans-Activators; D014157:Transcription Factors / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism*; D014981:Xenopus; D029867:Xenopus Proteins; D051176:beta Catenin
C495266:CTNNB1 protein, Xenopus; D003598:Cytoskeletal Proteins; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D008164:Luminescent Proteins; D051821:Lymphoid Enhancer-Binding Factor 1; D000071250:Snail Family Transcription Factors; D015534:Trans-Activators; D014157:Transcription Factors; D029867:Xenopus Proteins; D051176:beta Catenin; D049452:Green Fluorescent Proteins