Transgelin is a direct target of TGF-beta/Smad3-dependent epithelial cell migration in lung fibrosis.
Enhanced transforming growth factor (TGF) -beta signaling contributes to idiopathic pulmonary fibrosis (IPF), a progressive and fatal disease characterized by alveolar epithelial type II (ATII) cell hyperplasia, (myo)fibroblast accumulation, and excessive extracellular matrix deposition. TGF-beta is a potent inducer of lung fibrosis, and it regulates the ATII cell phenotype; however, direct TGF-beta target genes controlling the ATII cell phenotype remain elusive. Here, we identified the transgelin (tagln) gene as a novel immediate target of TGF-beta/Smad3-dependent gene expression in ATII cells using a Smad3 chromatin immunoprecipitation (ChIP) screen. Direct ChIP confirmed the rapid and specific binding of Smad3 to the tagln promoter. Luciferase assays demonstrated transactivation of the tagln promoter by activin-like kinase (Alk) 5-mediated TGF-beta signaling. TGF-beta treatment resulted in rapid up-regulation of tagln, but not tagln2, mRNA and protein expression, assessed by reverse transcription-polymerase chain reaction (RT-PCR), Western blotting, and immunofluorescence. In vivo, tagln expression was significantly increased in ATII cells of mice during bleomycin-induced lung fibrosis, as well as in lung specimen obtained from IPF patients, as assessed by RT-PCR and immunohistochemistry. Knockdown of tagln using siRNA inhibited TGF-beta-induced migration of lung epithelial A549 cells, as well as primary ATII cells. We thus identified tagln as a novel target of TGF-beta/Smad3-dependent gene expression in ATII cells. Increased ATII cell expression of tagln in experimental and idiopathic pulmonary fibrosis may contribute to TGF-beta-dependent ATII cell injury, repair, and migration in lung fibrosis.
Yu
Haiying
H
University of Giessen Lung Center, Department of Medicine II, Justus Liebig University Giessen, D-35392 Giessen, Germany.
Königshoff
Melanie
M
Jayachandran
Aparna
A
Handley
Dan
D
Seeger
Werner
W
Kaminski
Naftali
N
Eickelberg
Oliver
O
D002460:Cell Line; D002465:Cell Movement; D004847:Epithelial Cells / Q000473:pathology*; D006801:Humans; D008840:Microfilament Proteins / Q000187:drug effects / Q000235:genetics*; D009124:Muscle Proteins / Q000187:drug effects / Q000235:genetics*; D011401:Promoter Regions, Genetic; D011658:Pulmonary Fibrosis / Q000473:pathology*; D018125:Receptors, Transforming Growth Factor beta; D051900:Smad3 Protein / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000494:pharmacology*
D008840:Microfilament Proteins; D009124:Muscle Proteins; D018125:Receptors, Transforming Growth Factor beta; D051900:Smad3 Protein; D016212:Transforming Growth Factor beta; C051615:transgelin