Wnt and Bmp signalling cooperatively regulate graded Emx2 expression in the dorsal telencephalon.
Pattern formation of the dorsal telencephalon is governed by a regionalisation process that leads to the formation of distinct domains, including the future hippocampus and neocortex. Recent studies have implicated signalling proteins of the Wnt and Bmp gene families as well as several transcription factors, including Gli3 and the Emx homeobox genes, in the molecular control of this process. The regulatory relationships between these genes, however, remain largely unknown. We have used transgenic analysis to investigate the upstream mechanisms for regulation of Emx2 in the dorsal telencephalon. We have identified an enhancer from the mouse Emx2 gene that drives specific expression of a lacZ reporter gene in the dorsal telencephalon. This element contains binding sites for Tcf and Smad proteins, transcriptional mediators of the Wnt and Bmp signalling pathway, respectively. Mutations of these binding sites abolish telencephalic enhancer activity, while ectopic expression of these signalling pathways leads to ectopic activation of the enhancer. These results establish Emx2 as a direct transcriptional target of Wnt and Bmp signalling and provide insights into a genetic hierarchy involving Gli3, Emx2 and Bmp and Wnt genes in the control of dorsal telencephalic development.
Theil
Thomas
T
Institute for Animal Developmental and Molecular Biology, Heinrich-Heine-University, D-40225 Düsseldorf, Germany. thomas.theil@uni-duesseldorf.de
Aydin
Songül
S
Koch
Silke
S
Grotewold
Lars
L
Rüther
Ulrich
U
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D019485:Bone Morphogenetic Proteins / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004742:Enhancer Elements, Genetic; D018507:Gene Expression Regulation, Developmental; D006023:Glycoproteins; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D051741:Kruppel-Like Transcription Factors; D051821:Lymphoid Enhancer-Binding Factor 1; D051379:Mice; D008817:Mice, Mutant Strains; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins; D015398:Signal Transduction; D051785:Smad Proteins; D013687:Telencephalon / Q000196:embryology*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D051153:Wnt Proteins; D029867:Xenopus Proteins; D029961:Zebrafish Proteins; D000074290:Zinc Finger Protein Gli3; D001616:beta-Galactosidase / Q000235:genetics; D000099260:Empty Spiracles Homeobox Proteins
D019485:Bone Morphogenetic Proteins; D004268:DNA-Binding Proteins; D006023:Glycoproteins; D018398:Homeodomain Proteins; D051741:Kruppel-Like Transcription Factors; D051821:Lymphoid Enhancer-Binding Factor 1; D009419:Nerve Tissue Proteins; D011506:Proteins; D011518:Proto-Oncogene Proteins; D012097:Repressor Proteins; D051785:Smad Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D051153:Wnt Proteins; D029867:Xenopus Proteins; D029961:Zebrafish Proteins; D000074290:Zinc Finger Protein Gli3; D001616:beta-Galactosidase; D000099260:Empty Spiracles Homeobox Proteins; C108003:GLI3 protein, Xenopus; C065683:GLI3 protein, human; C465571:Gli3 protein, mouse; C490675:WNT7B protein, human; C490676:Wnt7B protein, Xenopus; C095937:Wnt7b protein, mouse; C490603:Wnt8b protein, mouse