title: Autophagy links β-catenin and Smad signaling to promote epithelial-mesenchymal transition via upregulation of integrin linked kinase.
abstract: TGF-β1 induces epithelial-mesenchymal transition (EMT) and autophagy in a variety of cells. However, the role of autophagy in TGF-β1-induced EMT has not been clearly elucidated and the underlying mechanisms are unclear. In the present study, we found that TGF-β1 induced both autophagy and EMT in mouse tubular epithelial C1.1 cells. Inhibition of autophagy by 3-methyladenine or siRNA knockdown of Beclin 1 reduced TGF-β1-induced increase of vimentin and decreased E-cadherin expression. In contrast, rapamycin-associated enhancement of TGF-β1-induced autophagy increased EMT of C1.1 cells. Serum rescue inhibited autophagy followed by reversal of EMT. Blocking of autophagosome-lysosomal but not proteosomal degradation reduced the decrease of E-cadherin, demonstrating a role for autophagy in degradation of E-cadherin during EMT. Autophagy promoted the activation of Src and Src-associated phosphorylation of β-catenin at Y-654 leading to pY654-β-catenin/p-Smad2 complex formation. Chromatin immunoprecipitation assay demonstrated binding by the pY654-β-catenin/p-Smad2 complex to ILK promoter thus increasing ILK expression. Taken together, our results demonstrate that TGF-β1-induced autophagy links β-catenin and Smad signaling to promote EMT in C1.1 cells through a novel pY654-β-catenin/p-Smad2/ILK pathway. The pathway delineated links disruption of E-cadherin/β-catenin-mediated cell-cell contact to induction of EMT via upregulation of ILK.
authors.affiliation: Centre for Transplantation and Renal Research, Westmead Millennium Institute, University of Sydney, Sydney NSW 2145, Australia; Dept. of Respiratory Medicine, First Hospital of Shanxi Medical University, Taiyuan 030001, PR China.
authors.forename: Min
authors.initials: M
authors.lastname: Pang
authors.affiliation: Centre for Transplantation and Renal Research, Westmead Millennium Institute, University of Sydney, Sydney NSW 2145, Australia; Dept. of Biochemistry and Molecular Biology, Shanxi Medical University, Taiyuan 030001, PR China.
authors.forename: Hailong
authors.initials: H
authors.lastname: Wang
authors.affiliation: Centre for Transplantation and Renal Research, Westmead Millennium Institute, University of Sydney, Sydney NSW 2145, Australia.
authors.forename: Padmashree
authors.initials: P
authors.lastname: Rao
authors.affiliation: Centre for Transplantation and Renal Research, Westmead Millennium Institute, University of Sydney, Sydney NSW 2145, Australia.
authors.forename: Ye
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Dept. of Biochemistry and Molecular Biology, Shanxi Medical University, Taiyuan 030001, PR China.
authors.forename: Jun
authors.initials: J
authors.lastname: Xie
authors.affiliation: Centre for Transplantation and Renal Research, Westmead Millennium Institute, University of Sydney, Sydney NSW 2145, Australia.
authors.forename: Qi
authors.initials: Q
authors.lastname: Cao
authors.affiliation: Centre for Transplantation and Renal Research, Westmead Millennium Institute, University of Sydney, Sydney NSW 2145, Australia.
authors.forename: Yiping
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Centre for Kidney Research, Children's Hospital at Westmead, Sydney NSW 2145, Australia.
authors.forename: Yuan Min
authors.initials: YM
authors.lastname: Wang
authors.affiliation: Centre for Transplantation and Renal Research, Westmead Millennium Institute, University of Sydney, Sydney NSW 2145, Australia.
authors.forename: Vincent W
authors.initials: VW
authors.lastname: Lee
authors.affiliation: Centre for Kidney Research, Children's Hospital at Westmead, Sydney NSW 2145, Australia.
authors.forename: Stephen I
authors.initials: SI
authors.lastname: Alexander
authors.affiliation: Centre for Transplantation and Renal Research, Westmead Millennium Institute, University of Sydney, Sydney NSW 2145, Australia.
authors.forename: David C H
authors.initials: DC
authors.lastname: Harris
authors.affiliation: Centre for Transplantation and Renal Research, Westmead Millennium Institute, University of Sydney, Sydney NSW 2145, Australia; Dept. of Biochemistry and Molecular Biology, Shanxi Medical University, Taiyuan 030001, PR China. Electronic address: guoping.zheng@sydney.edu.au.
authors.forename: Guoping
authors.initials: G
authors.lastname: Zheng
mesh_terms: D000818:Animals; D001343:Autophagy / Q000502:physiology*; D002460:Cell Line; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism*; D058750:Epithelial-Mesenchymal Transition / Q000502:physiology*; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D007684:Kidney Tubules / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D017346:Protein Serine-Threonine Kinases / Q000096:biosynthesis* / Q000235:genetics; D051899:Smad2 Protein / Q000235:genetics / Q000378:metabolism*; D053773:Transforming Growth Factor beta1 / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation / Q000502:physiology*; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism*; D000099200:Scaffold Protein ILK
chemical_list: D017346:Protein Serine-Threonine Kinases; D051899:Smad2 Protein; D053773:Transforming Growth Factor beta1; D051176:beta Catenin; D000099200:Scaffold Protein ILK; C497783:Smad2 protein, mouse; C508961:Tgfb1 protein, mouse
keywords: Autophagy; EMT; ILK; Smad2; TGF-β1; β-catenin