title: Tgm2/Gh, Gbx1 and TGF-beta are involved in retinoic acid-induced transdifferentiation from epidermis to mucosal epithelium.
abstract: We previously demonstrated that retinoic acid (RA) induces epidermis to transdifferentiate to mucosal epithelium with goblet cells in chick embryonic cultured skin. To characterize the molecular mechanism of this transdifferentiation process, we used rat embryonic cultured skin and immunohistochemistry to confirm that RA-induced epidermal transdifferentiation accompanies the expression of markers of esophagus epithelium. Because Gbx1, TG2/Gh (transglutaminase2) and TGF-beta2 are reported individually to be induced by RA in cultures of chick embryonic skin, mouse epidermal cells and human hair follicles respectively, here, we investigated whether cooperative interplay of Gbx1, TG2/Gh and TGF-beta2 is required for the transdifferentiation of epidermal cells to mucosal cells. We have shown that expression of Gbx1, TG2/Gh and TGF-beta proteins were all upregulated in RA-induced transdifferentiated skin and that the former two were expressed in the epidermis, while TGF-beta was expressed in the dermis. Inhibitors of the TGF-beta signal pathway partially inhibited transdifferentiation. Overexpression of both hTG2/Gh and mGbx1 together in the epidermis by electroporation resulted in cuboidal cells in the upper cell layers of the epidermis without keratinized layers, although epidermal keratinization was observed in skin by overexpression of either of them. Labeling DNA with BrdU indicated that RA directly transdifferentiated transient amplifying epidermal cells, not stem cells, to mucosal cells. This study showed that coexpression of TG/2 and Gbx1 in the epidermis was required for esophagus-like mucosal transdifferentiation, and that increase in TGF-beta2 expression by RA in the dermis was essential to induce transdifferentiation through epithelial-mesenchymal interaction.
authors.affiliation: Department of Physiological Chemistry II, Faculty of Pharmaceutical Sciences, Teikyo University, Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Obinata
authors.forename: Keitarou
authors.initials: K
authors.lastname: Osakabe
authors.forename: Mari
authors.initials: M
authors.lastname: Yamaguchi
authors.forename: Riyo
authors.initials: R
authors.lastname: Morimoto
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Akimoto
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D054338:Cell Transdifferentiation; D004247:DNA / Q000378:metabolism; D020405:Dermis / Q000378:metabolism; D004817:Epidermis / Q000196:embryology; D004848:Epithelium / Q000378:metabolism / Q000473:pathology; D019204:GTP-Binding Proteins / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000502:physiology*; D008954:Models, Biological; D009092:Mucous Membrane / Q000196:embryology; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D051381:Rats; D015398:Signal Transduction; D016212:Transforming Growth Factor beta / Q000502:physiology*; D011503:Transglutaminases / Q000502:physiology*; D014212:Tretinoin / Q000378:metabolism*
chemical_list: C572373:Gbx1 protein, rat; D018398:Homeodomain Proteins; C000717608:TGM2 protein, human; C000717609:Tgm2 protein, rat; D016212:Transforming Growth Factor beta; D014212:Tretinoin; D004247:DNA; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011503:Transglutaminases; D019204:GTP-Binding Proteins