title: Transient and recurrent expression of the Egr-1 gene in epithelial and mesenchymal cells during tooth morphogenesis suggests involvement in tissue interactions and in determination of cell fate.
abstract: We have analyzed the expression of early growth response gene (Egr-1) by mRNA in situ hybridization during mouse embryonic tooth development and in experimental recombinations of dental epithelium and mesenchyme. Egr-1 was transiently and recurrently expressed both in epithelial and mesenchymal cells starting from day 13 of gestation and up to 4 days after birth. The expression correlated with developmental transition points of dental mesenchymal and epithelial cells suggesting a role for Egr-1 in sequential determination and differentiation of cells. In recombination cultures of early dental epithelium and mesenchyme Egr-1 RNA was localized at the epithelial-mesenchymal interface in mesenchymal cells, and in two cases also in epithelial cells. These data indicate that Egr-1 expression may be regulated by epithelial-mesenchymal interactions when they are specific enough to initiate differentiation. We have also analyzed by in situ hybridization whether Wilms' tumour-1 gene (wt-1) is expressed in the developing tooth as it was proposed on the bases of in vitro studies that it may inhibit Egr-1 expression. No wt-1 expression was detected at any stage of tooth development showing that wt-1 is not obligatory for regulation of Egr-1 expression.
authors: Department of Pedodontics and Orthodontics, University of Helsinki, Finland.
authors: I
authors: I
authors: Karavanova
authors: S
authors: S
authors: Vainio
authors: I
authors: I
authors: Thesleff
mesh_terms: D000818:Animals; D004847:Epithelial Cells; D005786:Gene Expression Regulation; D016162:Genes, Wilms Tumor; D017403:In Situ Hybridization; D008648:Mesoderm / Q000166:cytology; D051379:Mice / Q000196:embryology / Q000235:genetics; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008963:Molar / Q000196:embryology; D009024:Morphogenesis; D009805:Odontogenesis / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis
chemical_list: D012333:RNA, Messenger