TGFbeta3 inhibits E-cadherin gene expression in palate medial-edge epithelial cells through a Smad2-Smad4-LEF1 transcription complex.
Dissociation of medial-edge epithelium (MEE) during palate development is essential for mediating correct craniofacial morphogenesis. This phenomenon is initiated by TGFbeta3 upon adherence of opposing palatal shelves, because loss of E-cadherin causes the MEE seam to break into small epithelial islands. To investigate the molecular mechanisms that cause this E-cadherin loss, we isolated and cultured murine embryonic primary MEE cells from adhered or non-adhered palates. Here, we provide the first evidence that lymphoid enhancer factor 1 (LEF1), when functionally activated by phosphorylated Smad2 (Smad2-P) and Smad4 (rather than beta-catenin), binds with the promoter of the E-cadherin gene to repress its transcription in response to TGFbeta3 signaling. Furthermore, we found that TGFbeta3 signaling stimulates epithelial-mesenchymal transformation (EMT) and cell migration in these cells. LEF1 and Smad4 were found to be necessary for up-regulation of the mesenchymal markers vimentin and fibronectin, independently of beta-catenin. We proved that TGFbeta3 signaling induces EMT in MEE cells by forming activated transcription complexes of Smad2-P, Smad4 and LEF1 that directly inhibit E-cadherin gene expression.
Nawshad
Ali
A
Department of Oral Biology, College of Dentistry, University of Nebraska Medical Center, Lincoln, NE 68583, USA. anawshad@unmc.edu
Medici
Damian
D
Liu
Chang-Chih
CC
Hay
Elizabeth D
ED
D000818:Animals; D001665:Binding Sites / Q000235:genetics; D015820:Cadherins / Q000235:genetics / Q000378:metabolism*; D002465:Cell Movement / Q000187:drug effects; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D047369:Chromatin Immunoprecipitation; D003593:Cytoplasm / Q000378:metabolism; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism*; D005353:Fibronectins / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects; D015151:Immunoblotting; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D051821:Lymphoid Enhancer-Binding Factor 1 / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008815:Mice, Inbred Strains; D009154:Mutation; D010159:Palate / Q000166:cytology / Q000196:embryology / Q000378:metabolism*; D011485:Protein Binding; D051899:Smad2 Protein / Q000235:genetics / Q000378:metabolism; D051901:Smad4 Protein / Q000235:genetics / Q000378:metabolism; D014162:Transfection; D053782:Transforming Growth Factor beta3 / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D014746:Vimentin / Q000378:metabolism; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism
D015820:Cadherins; D005353:Fibronectins; C497574:Lef1 protein, mouse; D051821:Lymphoid Enhancer-Binding Factor 1; D051899:Smad2 Protein; C497783:Smad2 protein, mouse; D051901:Smad4 Protein; C490810:Smad4 protein, mouse; C509045:Tgfb3 protein, mouse; D053782:Transforming Growth Factor beta3; D014746:Vimentin; D051176:beta Catenin; D008156:Luciferases