Interactions Between β-Catenin and Transforming Growth Factor-β Signaling Pathways Mediate Epithelial-Mesenchymal Transition and Are Dependent on the Transcriptional Co-activator cAMP-response Element-binding Protein (CREB)-binding Protein (CBP)
Interactions Between β-Catenin and Transforming Growth Factor-β Signaling Pathways Mediate Epithelial-Mesenchymal Transition and Are Dependent on the Transcriptional Co-activator cAMP-response Element-binding Protein (CREB)-binding Protein (CBP)
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DOI：
10.1074/jbc.m111.276311
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发表时间：
2012-03-02
影响因子：
4.8
通讯作者：
Borok, Zea
中科院分区：
文献类型：
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作者：
Zhou, Beiyun;Liu, Yixin;Borok, Zea
转化生长因子- β (tgf - β)和Wnt之间的相互作用对许多生物过程至关重要，尽管在许多情况下，具体的靶点、不同结果的基本原理（分化、上皮细胞增殖阻滞、上皮-间质转化（EMT））和精确的机制仍不清楚。我们研究了在EMT和肺纤维化的背景下，β -连环蛋白依赖性和转化生长因子- β 1 （tgf - β 1）在肺泡上皮细胞（AEC）中的相互作用。我们之前证明了ICG-001，一种β -catenin/CBP（但不是β -catenin/p300）相互作用的小分子特异性抑制剂，改善和逆转肺纤维化，抑制tgf - β 1介导的α -平滑肌肌动蛋白（α - sma）和AEC中胶原诱导。我们现在证明tgf - β 1诱导LEF/TCF TOPFLASH报告因子激活和核β -连环蛋白积累，而LiCl增强tgf - β诱导的α - sma表达，进一步证实β -连环蛋白和tgf - β依赖的信号通路之间的合作。抑制和敲低Smad3、敲低β -catenin和过表达ICAT可消除tgf - β 1对α - sma转录/表达的影响，表明在这些Smad3依赖性作用中需要β -catenin。在tgf - β治疗后，共免疫沉淀证实了内源性Smad3和β -连环蛋白之间的直接相互作用，而染色质免疫沉淀（ChIP）re-ChIP通过Smad3、β -连环蛋白和CBP之间的复合物形成确定了α - sma的时空调节。ICG-001在tgf - β以及β -catenin和CBP占据α - sma启动子的情况下抑制了α - sma的表达/转录，证明了tgf - β 1/ β -catenin/CBP介导的前emt信号通路是之前未知的必要条件。IPF患者AEC中β -catenin/Smad3共定位和CBP表达显示了临床相关性。这些发现提示通过特异性地解耦tgf - β下游的CBP/catenin依赖性信号来治疗肺纤维化的新方法。
Interactions between transforming growth factor-beta (TGF-beta) and Wnt are crucial to many biological processes, although specific targets, rationale for divergent outcomes (differentiation versus block of epithelial proliferation versus epithelial-mesenchymal transition (EMT)) and precise mechanisms in many cases remain unknown. We investigated beta-catenin-dependent and transforming growth factor-beta 1 (TGF-beta 1) interactions in pulmonary alveolar epithelial cells (AEC) in the context of EMT and pulmonary fibrosis. We previously demonstrated that ICG-001, a small molecule specific inhibitor of the beta-catenin/CBP (but not beta-catenin/p300) interaction, ameliorates and reverses pulmonary fibrosis and inhibits TGF-beta 1-mediated alpha-smooth muscle actin (alpha-SMA) and collagen induction in AEC. We now demonstrate that TGF-beta 1 induces LEF/TCF TOPFLASH reporter activation and nuclear beta-catenin accumulation, while LiCl augments TGF-beta-induced alpha-SMA expression, further confirming co-operation between beta-catenin- and TGF-beta-dependent signaling pathways. Inhibition and knockdown of Smad3, knockdown of beta-catenin and overexpression of ICAT abrogated effects of TGF-beta 1 on alpha-SMA transcription/expression, indicating a requirement for beta-catenin in these Smad3-dependent effects. Following TGF-beta treatment, co-immunoprecipitation demonstrated direct interaction between endogenous Smad3 and beta-catenin, while chromatin immunoprecipitation (ChIP)re-ChIP identified spatial and temporal regulation of alpha-SMA via complex formation among Smad3, beta-catenin, and CBP. ICG-001 inhibited alpha-SMA expression/transcription in response to TGF-beta as well as alpha-SMA promoter occupancy by beta-catenin and CBP, demonstrating a previously unknown requisite TGF-beta 1/beta-catenin/CBP-mediated pro-EMT signaling pathway. Clinical relevance was shown by beta-catenin/Smad3 co-localization and CBP expression in AEC of IPF patients. These findings suggest a new therapeutic approach to pulmonary fibrosis by specifically uncoupling CBP/catenin-dependent signaling downstream of TGF-beta.