TGFβ3 inhibits E-cadherin gene expression in palate medial-edge epithelial cells through a Smad2-Smad4-LEF1 transcription complex
TGFβ3 inhibits E-cadherin gene expression in palate medial-edge epithelial cells through a Smad2-Smad4-LEF1 transcription complex
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DOI：
10.1242/jcs.003129
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发表时间：
2007-05-01
影响因子：
4
通讯作者：
Hay, Elizabeth D.
中科院分区：
文献类型：
--
作者：
Nawshad, Ali;Medici, Damian;Hay, Elizabeth D.
在腭发育过程中，中缘上皮的分离对于调节正确的颅面形态发生至关重要。这种现象是由TGF β 3在相对的腭架粘附时引发的，因为E-钙粘蛋白的缺失导致腭缝破裂成小的上皮岛。为了研究导致E-cadherin丢失的分子机制，我们从粘附或非粘附的腭分离和培养小鼠胚胎原代胰岛细胞。在这里，我们提供了第一个证据表明，淋巴增强因子1（LEF 1），当功能激活磷酸化Smad 2（Smad 2-P）和Smad 4（而不是β-连环蛋白），结合E-钙粘蛋白基因的启动子，抑制其转录响应TGF β 3信号。此外，我们发现TGF β 3信号刺激这些细胞中的上皮-间充质转化（EMT）和细胞迁移。LEF 1和Smad 4被认为是上调间充质标志物波形蛋白和纤连蛋白所必需的，独立于β-连环蛋白。我们证明TGF β 3信号通过形成Smad 2-P、Smad 4和LEF 1的激活转录复合物直接抑制E-cadherin基因的表达，从而诱导EMT。
Dissociation of medial-edge epithelium (MEE) during palate development is essential for mediating correct craniofacial morphogenesis. This phenomenon is initiated by TGF beta 3 upon adherence of opposing palatal shelves, because loss of E-cadherin causes the MEE seam to break into small epithelial islands. To investigate the molecular mechanisms that cause this E-cadherin loss, we isolated and cultured murine embryonic primary MEE cells from adhered or non-adhered palates. Here, we provide the first evidence that lymphoid enhancer factor 1 (LEF1), when functionally activated by phosphorylated Smad2 (Smad2-P) and Smad4 (rather than beta-catenin), binds with the promoter of the E-cadherin gene to repress its transcription in response to TGF beta 3 signaling. Furthermore, we found that TGF beta 3 signaling stimulates epithelial-mesenchymal transformation (EMT) and cell migration in these cells. LEF1 and Smad4 were found to be necessary for up-regulation of the mesenchymal markers vimentin and fibronectin, independently of beta-catenin. We proved that TGF beta 3 signaling induces EMT in MEE cells by forming activated transcription complexes of Smad2-P, Smad4 and LEF1 that directly inhibit E-cadherin gene expression.