title: The transcription factors Tbx18 and Wt1 control the epicardial epithelial-mesenchymal transition through bi-directional regulation of Slug in murine primary epicardial cells.
abstract: During cardiac development, a subpopulation of epicardial cells migrates into the heart as part of the epicardial epithelial-mesenchymal transition (EMT) and differentiates into smooth muscle cells and fibroblasts. However, the roles of transcription factors in the epicardial EMT are poorly understood. Here, we show that two transcription factors expressed in the developing epicardium, T-box18 (Tbx18) and Wilms' tumor 1 homolog (Wt1), bi-directionally control the epicardial EMT through their effects on Slug expression in murine primary epicardial cells. Knockdown of Wt1 induced the epicardial EMT, which was accompanied by an increase in the migration and expression of N-cadherin and a decrease in the expression of ZO-1 as an epithelial marker. By contrast, knockdown of Tbx18 inhibited the mesenchymal transition induced by TGFβ1 treatment and Wt1 knockdown. The expression of Slug but not Snail decreased as a result of Tbx18 knockdown, but Slug expression increased following knockdown of Wt1. Knockdown of Slug also attenuated the epicardial EMT induced by TGFβ1 treatment and Wt1 knockdown. Furthermore, in normal murine mammary gland-C7 (NMuMG-C7) cells, Tbx18 acted to increase Slug expression, while Wt1 acted to decrease Slug expression. Chromatin immunoprecipitation and promoter assay revealed that Tbx18 and Wt1 directly bound to the Slug promoter region and regulated Slug expression. These results provide new insights into the regulatory mechanisms that control the epicardial EMT.
authors.affiliation: Division of Gene Therapy Science, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan.
authors.forename: Makiko
authors.initials: M
authors.lastname: Takeichi
authors.forename: Keisuke
authors.initials: K
authors.lastname: Nimura
authors.forename: Masaki
authors.initials: M
authors.lastname: Mori
authors.forename: Hironori
authors.initials: H
authors.lastname: Nakagami
authors.forename: Yasufumi
authors.initials: Y
authors.lastname: Kaneda
mesh_terms: D000818:Animals; D004622:Embryo, Mammalian / Q000166:cytology; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects; D055785:Gene Knockdown Techniques; D006321:Heart / Q000254:growth & development; D051379:Mice; D010496:Pericardium / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D000071250:Snail Family Transcription Factors; D020825:T-Box Domain Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics*; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology; D025721:WT1 Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*
chemical_list: C000604449:Snai2 protein, mouse; D000071250:Snail Family Transcription Factors; D020825:T-Box Domain Proteins; C420983:Tbx18 protein, mouse; D014157:Transcription Factors; D053773:Transforming Growth Factor beta1; D025721:WT1 Proteins