Dach1 deficiency drives alveolar epithelium apoptosis in pulmonary fibrosis via modulating C-Jun/Bim activity

Dysregulation of type II alveolar epithelial cells (AECII) plays a vital role in the initiation and development of pulmonary fibrosis (PF). Dachshund homolog 1 (Dach1), frequently expressed in epithelial cells with stem cell potential, controls cell proliferation, apoptosis, and cell cycle in tissue development and disease process. In this study, we demonstrated that the lungs collected from PF patients and mice of Bleomycin (BLM)-treated were characterized by low expression of Dachshund homolog 1 (Dach1), especially in AECII. Dach1 deficiency in the alveolar epithelium exacerbated PF in BLM-treated mice, as evidenced by reduced pulmonary function and increased expression of fibrosis markers. Rather, treatment with lung-specific overexpression of Dach1 alleviated histopathological damage, lung compliance, and fibrosis in BLM-treated mice. Moreover, overexpression of Dach1 could inhibit epithelial apoptosis in vitro. Conversely, primary AECII with Dach1 depletion were more susceptible to apoptosis in vivo. Mechanically, Dach1 combined with C-Jun protooncogene selectively bound to the promoter of B-cell lymphoma 2 interacting mediators of cell death (Bim), by which it repressed Bim expression and alleviated epithelial apoptosis. Taken together, our data support that Dach1 in AECII contributes to the progression of PF and may be a viable target for the prevention and treatment of PF.