title: Association of β-catenin with P-Smad3 but not LEF-1 dissociates in vitro profibrotic from anti-inflammatory effects of TGF-β1.
abstract: Transforming growth factor β1 (TGF-β1) is known to be both anti-inflammatory and profibrotic. Cross-talk between TGF-β/Smad and Wnt/β-catenin pathways in epithelial-mesenchymal transition (EMT) suggests a specific role for β-catenin in profibrotic effects of TGF-β1. However, no such mechanistic role has been demonstrated for β-catenin in the anti-inflammatory effects of TGF-β1. In the present study, we explored the role of β-catenin in the profibrotic and anti-inflammatory effects of TGF-β1 by using a cytosolic, but not membrane, β-catenin knockdown chimera (F-TrCP-Ecad) and the β-catenin/CBP inhibitor ICG-001. TGF-β1 induced nuclear Smad3/β-catenin complex, but not β-catenin/LEF-1 complex or TOP-flash activity, during EMT of C1.1 (renal tubular epithelial) cells. F-TrCP-Ecad selectively degraded TGF-β1-induced cytoplasmic β-catenin and blocked EMT of C1.1 cells. Both F-TrCP-Ecad and ICG-001 blocked TGF-β1-induced Smad3/β-catenin and Smad reporter activity in C1.1 cells, suggesting that TGF-β1-induced EMT depends on β-catenin binding to Smad3, but not LEF-1 downstream of Smad3, through canonical Wnt. In contrast, in J774 macrophages, the β-catenin level was low and was not changed by interferon-γ (IFN-γ) or lipopolysaccharide (LPS) with or without TGF-β1. TGF-β1 inhibition of LPS-induced TNF-α and IFN-γ-stimulated inducible NO synthase (iNOS) expression was not affected by F-TrCP-Ecad, ICG-001 or by overexpression of wild-type β-catenin in J774 cells. Inhibition of β-catenin by either F-TrCP-Ecad or ICG-001 abolished LiCl-induced TOP-flash, but not TGF-β1-induced Smad reporter, activity in J774 cells. These results demonstrate for the first time that β-catenin is required as a co-factor of Smad in TGF-β1-induced EMT of C1.1 epithelial cells, but not in TGF-β1 inhibition of macrophage activation. Targeting β-catenin may dissociate the TGF-β1 profibrotic and anti-inflammatory effects.
authors.affiliation: Centre for Transplantation and Renal Research, the University of Sydney at Westmead Millennium Institute, Sydney, NSW 2145, Australia.
authors.forename: Xinrui
authors.initials: X
authors.lastname: Tian
authors.forename: Jianlin
authors.initials: J
authors.lastname: Zhang
authors.forename: Thian Kui
authors.initials: TK
authors.lastname: Tan
authors.forename: J Guy
authors.initials: JG
authors.lastname: Lyons
authors.forename: Hong
authors.initials: H
authors.lastname: Zhao
authors.forename: Bo
authors.initials: B
authors.lastname: Niu
authors.forename: So Ra
authors.initials: SR
authors.lastname: Lee
authors.forename: Tania
authors.initials: T
authors.lastname: Tsatralis
authors.forename: Ye
authors.initials: Y
authors.lastname: Zhao
authors.forename: Ya
authors.initials: Y
authors.lastname: Wang
authors.forename: Qi
authors.initials: Q
authors.lastname: Cao
authors.forename: Changqi
authors.initials: C
authors.lastname: Wang
authors.forename: Yiping
authors.initials: Y
authors.lastname: Wang
authors.forename: Vincent W S
authors.initials: VW
authors.lastname: Lee
authors.forename: Michael
authors.initials: M
authors.lastname: Kahn
authors.forename: Guoping
authors.initials: G
authors.lastname: Zheng
authors.forename: David C H
authors.initials: DC
authors.lastname: Harris
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D015153:Blotting, Western; D002460:Cell Line; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects / Q000235:genetics; D047468:Immunoprecipitation; D051821:Lymphoid Enhancer-Binding Factor 1 / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008856:Microscopy, Fluorescence; D011485:Protein Binding / Q000187:drug effects; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051900:Smad3 Protein / Q000235:genetics / Q000378:metabolism*; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology*; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism*
chemical_list: D000893:Anti-Inflammatory Agents; D051821:Lymphoid Enhancer-Binding Factor 1; D051900:Smad3 Protein; D053773:Transforming Growth Factor beta1; D051176:beta Catenin