Sirtuin 6 inhibits epithelial to mesenchymal transition during idiopathic pulmonary fibrosis via inactivating TGF-β1/Smad3 signaling

Sirt6 which is implicated in the control of aging, cancer, and metabolism, has been shown to have anti-fibrosis function in heart and liver. However, whether Sirt6 inhibits idiopathic pulmonary fibrosis remains elusive. Epithelial to mesenchymal transition has been found to be involved in the pathogenesis of idiopathic pulmonary fibrosis. In the present study, forced expression of Sirt6 significantly abrogated TGF-β1-induced epithelial to mesenchymal transition-like phenotype and cell behaviors in A549 cells. Additionally, activation of TGF-β1/Smad3 signaling pathway and binding of Smad3-Snail1 were ameliorated by overexpression of wild-type Sirt6 but not mutant Sirt6 (H133Y) without histone deacetylase activity. Meanwhile, upregulation of epithelial to mesenchymal transition-related transcription factors by TGF-β1 were also restored by overexpression of wild-type Sirt6 but not mutant Sirt6. Furthermore, in vivo study showed that lung targeted delivery of Sirt6 using adeno-associated virus injection blunted bleomycin-induced pulmonary epithelial to mesenchymal transition and fibrosis. Overall, our findings unravel that Sirt6 acts as a key modulator in epithelial to mesenchymal transition process, suggesting Sirt6 may be an attractive potential therapeutic target for idiopathic pulmonary fibrosis.