TGFbeta3 signaling activates transcription of the LEF1 gene to induce epithelial mesenchymal transformation during mouse palate development.
Epithelial mesenchymal transformation (EMT) of the medial edge epithelial (MEE) seam creates palatal confluence. This work aims to elucidate the molecular mechanisms by which TGFbeta3 brings about palatal seam EMT. We collected mRNA for PCR analysis from individual transforming MEE cells by laser microdissection techniques and demonstrated that TGFbeta3 stimulates lymphoid-enhancing factor 1 (LEF1) mRNA synthesis in MEE cells. We show with antisense beta-catenin oligonucleotides that up-regulated LEF1 is not activated by beta-catenin in palate EMT. We ruled out other TGFbeta3 targets, such as RhoA and MEK1/2 pathways, and we present evidence using dominant-negative Smad4 and dominant-negative LEF1 showing that TGFbeta3 uses Smads both to up-regulate synthesis of LEF1 and to activate LEF1 transcription during induction of palatal EMT. When phospho-Smad2 and Smad4 are present in the nucleus, LEF1 is activated without beta-catenin. Our paper is the first to show that the Smad2,4/LEF1 complex replaces beta-catenin/LEF1 during activation of EMT in vivo by TGFbeta3.
Nawshad
Ali
A
Department of Cell Biology, Harvard Medical School, 220 Longwood Ave., B-1, Room 342, Boston, MA 02115-6092, USA.
Hay
Elizabeth D
ED
D000818:Animals; D002454:Cell Differentiation / Q000235:genetics; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000378:metabolism / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004848:Epithelium / Q000196:embryology* / Q000378:metabolism; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000235:genetics; D051821:Lymphoid Enhancer-Binding Factor 1; D046911:Macromolecular Substances; D008648:Mesoderm / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D020320:Oligoribonucleotides, Antisense / Q000494:pharmacology; D010159:Palate / Q000166:cytology / Q000196:embryology* / Q000378:metabolism; D011247:Pregnancy; D012333:RNA, Messenger / Q000378:metabolism; D051899:Smad2 Protein; D051901:Smad4 Protein; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation / Q000235:genetics; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism*; D053782:Transforming Growth Factor beta3; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics; D051176:beta Catenin
C495267:CTNNB1 protein, mouse; D003598:Cytoskeletal Proteins; D004268:DNA-Binding Proteins; C497574:Lef1 protein, mouse; D051821:Lymphoid Enhancer-Binding Factor 1; D046911:Macromolecular Substances; D020320:Oligoribonucleotides, Antisense; D012333:RNA, Messenger; D051899:Smad2 Protein; C497783:Smad2 protein, mouse; D051901:Smad4 Protein; C490810:Smad4 protein, mouse; C509045:Tgfb3 protein, mouse; D015534:Trans-Activators; D014157:Transcription Factors; D016212:Transforming Growth Factor beta; D053782:Transforming Growth Factor beta3; D051176:beta Catenin