Enhanced transforming growth factor (TGF) ‐β 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‐β is a potent inducer of lung fibrosis, and it regulates the ATII cell phenotype; however, direct TGF‐β target genes controlling the ATII cell phenotype remain elusive. Here, we identified the transgelin (tagln) gene as a novel immediate target of TGF‐β/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‐β signaling. TGF‐β 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‐β‐induced migration of lung epithelial A549 cells, as well as primary ATII cells. We thus identified tagln as a novel target of TGF‐β/Smad3‐dependent gene expression in ATII cells. Increased ATII cell expression of tagln in experimental and idiopathic pulmonary fibrosis may contribute to TGF‐β‐dependent ATII cell injury, repair, and migration in lung fibrosis.— Yu, H., Konigshoff, M., Jayachandran, A., Handley, D., Seeger, W., Kaminski, N., Eickelberg, O. Transgelin is a direct target of TGF‐β/Smad3‐dependent epithelial cell migration in lung fibrosis. FASEB J. 22, 1778–1789 (2008)