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)

TitleInteractions 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)
Publication TypeJournal Article
Year of Publication2012
AuthorsZhou B, Liu Y, Kahn M, Ann DK, Han A, Wang H, Nguyen C, Flodby P, Zhong Q, Krishnaveni MS, Liebler JM, Minoo P, Crandall ED, Borok Z
JournalJ Biol Chem
Volume287
Issue10
Pagination7026-38
Date Published2012 Mar 2
ISSN1083-351X
KeywordsActins, beta Catenin, Bicyclo Compounds, Heterocyclic, Cell Line, Cell Proliferation, CREB-Binding Protein, Epithelial Cells, Epithelial-Mesenchymal Transition, Gene Expression Regulation, Humans, Pulmonary Fibrosis, Pyrimidinones, Signal Transduction, Smad3 Protein, Transforming Growth Factor beta1
Abstract

Interactions between transforming growth factor-β (TGF-β) 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 β-catenin-dependent and transforming growth factor-β1 (TGF-β1) 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 β-catenin/CBP (but not β-catenin/p300) interaction, ameliorates and reverses pulmonary fibrosis and inhibits TGF-β1-mediated α-smooth muscle actin (α-SMA) and collagen induction in AEC. We now demonstrate that TGF-β1 induces LEF/TCF TOPFLASH reporter activation and nuclear β-catenin accumulation, while LiCl augments TGF-β-induced α-SMA expression, further confirming co-operation between β-catenin- and TGF-β-dependent signaling pathways. Inhibition and knockdown of Smad3, knockdown of β-catenin and overexpression of ICAT abrogated effects of TGF-β1 on α-SMA transcription/expression, indicating a requirement for β-catenin in these Smad3-dependent effects. Following TGF-β treatment, co-immunoprecipitation demonstrated direct interaction between endogenous Smad3 and β-catenin, while chromatin immunoprecipitation (ChIP)-re-ChIP identified spatial and temporal regulation of α-SMA via complex formation among Smad3, β-catenin, and CBP. ICG-001 inhibited α-SMA expression/transcription in response to TGF-β as well as α-SMA promoter occupancy by β-catenin and CBP, demonstrating a previously unknown requisite TGF-β1/β-catenin/CBP-mediated pro-EMT signaling pathway. Clinical relevance was shown by β-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-β.

DOI10.1074/jbc.M111.276311
Alternate JournalJ. Biol. Chem.
PubMed ID22241478
PubMed Central IDPMC3293544
Grant ListDE010742 / DE / NIDCR NIH HHS / United States
DE014183 / DE / NIDCR NIH HHS / United States
ES017034 / ES / NIEHS NIH HHS / United States
ES018782 / ES / NIEHS NIH HHS / United States
HL038578 / HL / NHLBI NIH HHS / United States
HL038621 / HL / NHLBI NIH HHS / United States
HL056590 / HL / NHLBI NIH HHS / United States
HL062569 / HL / NHLBI NIH HHS / United States
HL073722 / HL / NHLBI NIH HHS / United States
HL089445 / HL / NHLBI NIH HHS / United States
HL095349 / HL / NHLBI NIH HHS / United States
NEI03040 / / PHS HHS / United States
P30 CA014089 / CA / NCI NIH HHS / United States
P30 DK048522 / DK / NIDDK NIH HHS / United States
R01 HL112638 / HL / NHLBI NIH HHS / United States
R37 HL062569 / HL / NHLBI NIH HHS / United States