Sox17 modulates Wnt3A/β-catenin-mediated transcriptional activation of the Lef-1 promoter
Sox17 modulates Wnt3A/β-catenin-mediated transcriptional activation of the Lef-1 promoter
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DOI：
10.1152/ajplung.00140.2010
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发表时间：
2010-11-01
影响因子：
4.9
通讯作者：
Engelhardt, John F.
中科院分区：
文献类型：
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作者：
Liu, Xiaoming;Luo, Meihui;Engelhardt, John F.
刘X，罗M，谢W，Wells JM，Goodheart MJ，Engelhardt JF。 Sox17 调节 Wnt3A/β-连环蛋白介导的 Lef-1 启动子转录激活。 Am J Physiol Lung Cell Mol Physiol 299：L694-L710，2010。首次发表于 2010 年 8 月 27 日； doi:10.1152/ajplung.00140.2010.-Wnt/β-连环蛋白依赖性淋巴增强因子 1 (Lef-1) 激活在许多发育过程中发挥重要作用。在这种情况下，Lef-1 基因的转录是通过 Wnt 介导的 Lef-1 启动子上的 TCF4/β-连环蛋白激活来增加的，其机制目前尚不清楚。在小鼠气道粘膜下腺祖细胞中，Wnt3A 短暂诱导 Lef-1 基因表达，该过程是上皮细胞增殖和腺体形态发生所必需的。在本研究中，我们试图鉴定腺体形态发生过程中 Lef-1 基因的其他候选转录调节因子。为此，我们发现在诱导 Lef-1 表达的早期腺祖细胞中，Sox17 表达显着下调。未分化的初级气道上皮细胞的 Wnt 刺激诱导了 Sox17 和 Lef-1 表达的类似变化。报告基因检测显示，Sox17 的异位表达会抑制细胞系中 Lef-1 启动子的 Wnt3A/β-catenin 激活。 EMSA 和 ChIP 分析确定了多个 Sox17 和 TCF4 结合位点，这些位点在 Lef-1 启动子的转录控制中协作。更具体地说，Sox17 直接或通过 TCF 复合物间接结合到 Lef-1 启动子中的四个位点。 Sox17 的 DNA 或 β-连环蛋白结合域控制 Lef-1 启动子上 Sox17/TCF 复合物的上下文特异性结合。 Lef-1启动子中Sox17或TCF结合位点的组合定点诱变证明这些位点控制Wnt/β-连环蛋白介导的诱导和/或抑制。这些发现首次证明Sox17可以直接调节Lef-1启动子的Wnt/β-连环蛋白依赖性转录，并揭示了Lef-1启动子中新的上下文依赖性结合位点，促进Sox17和TCF4之间的蛋白质-蛋白质相互作用。
Liu X, Luo M, Xie W, Wells JM, Goodheart MJ, Engelhardt JF. Sox17 modulates Wnt3A/beta-catenin-mediated transcriptional activation of the Lef-1 promoter. Am J Physiol Lung Cell Mol Physiol 299: L694-L710, 2010. First published August 27, 2010; doi:10.1152/ajplung.00140.2010.-Wnt/beta-catenin-dependent activation of lymphoid enhancer factor 1 (Lef-1) plays an important role in numerous developmental processes. In this context, transcription of the Lef-1 gene is increased by Wnt-mediated TCF4/beta-catenin activation on the Lef-1 promoter through mechanisms that remain poorly defined. In mouse airway submucosal gland progenitor cells, Wnt3A transiently induces Lef-1 gene expression, and this process is required for epithelial cell proliferation and glandular morphogenesis. In the present study, we sought to identify additional candidate transcriptional regulators of the Lef-1 gene during glandular morphogenesis. To this end, we found that Sox17 expression is dramatically down-regulated in early glandular progenitor cells that induce Lef-1 expression. Wnt stimulation of undifferentiated primary airway epithelial cells induced similar changes in Sox17 and Lef-1 expression. Reporter assays revealed that ectopic expression of Sox17 suppresses Wnt3A/beta-catenin activation of the Lef-1 promoter in cell lines. EMSA and ChIP analyses defined several Sox17- and TCF4-binding sites that collaborate in transcriptional control of the Lef-1 promoter. More specifically, Sox17 bound to four sites in the Lef-1 promoter, either directly or indirectly through TCF complexes. The DNA-or beta-catenin-binding domains of Sox17 controlled context-specific binding of Sox17/TCF complexes on the Lef-1 promoter. Combinatorial site-directed mutagenesis of Sox17-or TCF-binding sites in the Lef-1 promoter demonstrated that these sites control Wnt/beta-catenin-mediated induction and/or repression. These findings demonstrate for the first time that Sox17 can directly regulate Wnt/beta-catenin-dependent transcription of the Lef-1 promoter and reveal new context-dependent binding sites in the Lef-1 promoter that facilitate protein-protein interactions between Sox17 and TCF4.