title: Fate-mapping of the epithelial seam during palatal fusion rules out epithelial-mesenchymal transformation.
abstract: During palatogenesis, fusion of the palatine shelves is a crucial event, the failure of which results in the birth defect, cleft palate. The fate of the midline epithelial seam (MES), which develops transiently upon contact of the two palatine shelves, is still strongly debated. Three major mechanisms underlying the regression of the MES upon palatal fusion have been proposed: (1) apoptosis has been evidenced by morphological and molecular criteria; (2) epithelial-mesenchymal transformation has been suggested based on ultrastructural and lipophilic dye cell labeling observations; and (3) migration of MES cells toward the oral and nasal areas has been proposed following lipophilic dye cell labeling. To verify whether epithelial-mesenchymal transformation of MES cells takes place during murine palatal fusion, we used the Cre/lox system to genetically mark Sonic hedgehog- and Keratin-14-expressing palatal epithelial cells and to identify their fate in vivo. Our analyses provide conclusive evidence that rules out the occurrence of epithelial-mesenchymal transformation of MES cells.
authors.affiliation: Department of Oral Biochemistry, Sahlgrenska Academy at Göteborg University, Medicinaregatan 12F, SE-405 30 Göteborg, Sweden.
authors.forename: Forugh
authors.initials: F
authors.lastname: Vaziri Sani
authors.forename: Kristina
authors.initials: K
authors.lastname: Hallberg
authors.forename: Brian D
authors.initials: BD
authors.lastname: Harfe
authors.forename: Andrew P
authors.initials: AP
authors.lastname: McMahon
authors.forename: Anders
authors.initials: A
authors.lastname: Linde
authors.forename: Amel
authors.initials: A
authors.lastname: Gritli-Linde
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000502:physiology*; D004847:Epithelial Cells / Q000166:cytology* / Q000378:metabolism / Q000502:physiology; D049452:Green Fluorescent Proteins; D053823:Hedgehog Proteins; D007150:Immunohistochemistry; D053547:Keratin-14; D007633:Keratins / Q000378:metabolism; D008648:Mesoderm / Q000166:cytology*; D051379:Mice; D008822:Mice, Transgenic; D009024:Morphogenesis / Q000502:physiology*; D010159:Palate / Q000196:embryology*; D015534:Trans-Activators / Q000378:metabolism
chemical_list: D053823:Hedgehog Proteins; D053547:Keratin-14; C507446:Krt14 protein, mouse; C465570:Shh protein, mouse; D015534:Trans-Activators; D049452:Green Fluorescent Proteins; D007633:Keratins