Axin pathway activity regulates in vivo pY654-β-catenin accumulation and pulmonary fibrosis.
Epithelial to mesenchymal transition (EMT) and pulmonary fibrogenesis require epithelial integrin α3β1-mediated cross-talk between TGFβ1 and Wnt signaling pathways. One hallmark of this cross-talk is pY654-β-catenin accumulation, but whether pY654-β-catenin is a biomarker of fibrogenesis or functionally important is unknown. To clarify further the role of β-catenin in fibrosis, we explored pY654-β-catenin generation and function. α3β1 was required for TGFβ1-mediated activation of Src family kinases, and Src inhibition blocked both pY654 and EMT in primary alveolar epithelial cells (AECs). TGFβ1 stimulated β-catenin/Lef1-dependent promoter activity comparably in immortalized AECs stably expressing WT β-catenin as well as Y654E or Y654F β-catenin point mutants. But EMT was abrogated in the Tyr to Phe mutant. pY654-β-catenin was sensitive to the axin β-catenin turnover pathway as inhibition of tankyrase 1 led to high AEC axin levels, loss of pY654-β-catenin, and inhibition of EMT ex vivo. Mice given a tankyrase inhibitor (50 mg/kg orally) daily for 7 days beginning 10 days after intratracheal bleomycin had improved survival over controls. Treated mice developed raised axin levels in the lung that abrogated pY654-β-catenin and attenuated lung Snail1, Twist1, α-smooth muscle actin, and type I collagen accumulation. Total β-catenin levels were unaltered. These findings identify Src kinase(s) as a mediator of TGFβ1-induced pY654-β-catenin, provide evidence that pY654-β-catenin levels are a critical determinant of EMT and fibrogenesis, and suggest regulation of axin levels as a novel therapeutic approach to fibrotic disorders.
Pulmonary and Critical Care Division, Department of Medicine and Cardiovascular Research Institute, University of California, San Francisco, California 94143, USA.
Arnau
A
Ulsamer
Ying
Y
Wei
Kevin K
KK
Kim
Kevin
K
Tan
Sarah
S
Wheeler
Ying
Y
Xi
R Scott
RS
Thies
Harold A
HA
Chapman
D019943:Amino Acid Substitution; D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000009:adverse effects / Q000494:pharmacology; D060466:Axin Protein; D001761:Bleomycin / Q000009:adverse effects / Q000494:pharmacology; D002461:Cell Line, Transformed; D024042:Collagen Type I / Q000096:biosynthesis* / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000378:metabolism* / Q000473:pathology; D058750:Epithelial-Mesenchymal Transition / Q000235:genetics; D039201:Integrin alpha3beta1 / Q000235:genetics / Q000378:metabolism; D051379:Mice; D020125:Mutation, Missense; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D011650:Pulmonary Alveoli / Q000378:metabolism* / Q000473:pathology; D011658:Pulmonary Fibrosis / Q000139:chemically induced / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D000071250:Snail Family Transcription Factors; D038501:Tankyrases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000235:genetics / Q000378:metabolism; D051879:Twist-Related Protein 1 / Q000235:genetics / Q000378:metabolism; D051176:beta Catenin
D000903:Antibiotics, Antineoplastic; D060466:Axin Protein; D024042:Collagen Type I; D004791:Enzyme Inhibitors; D039201:Integrin alpha3beta1; D009687:Nuclear Proteins; C000604429:Snai1 protein, mouse; D000071250:Snail Family Transcription Factors; D014157:Transcription Factors; D053773:Transforming Growth Factor beta1; D051879:Twist-Related Protein 1; D051176:beta Catenin; D001761:Bleomycin; C067250:Twist1 protein, mouse; D038501:Tankyrases