Dysregulated overexpression of Sox9 induces fibroblast activation in pulmonary fibrosis

• Published in: JCI insight 2021-10, Vol.6 (20)
• Main Authors: Gajjala, Prathibha R, Kasam, Rajesh K, Soundararajan, Divyalakshmi, Sinner, Debora, Huang, Steven K, Jegga, Anil G, Madala, Satish K
• Format: Article
• Language: English
• Subjects: Animals; Cell Proliferation; Disease Models, Animal; Fibroblasts - metabolism; Mice; Pulmonary Fibrosis - genetics; Pulmonary Fibrosis - pathology; Pulmonology; Signal Transduction; SOX9 Transcription Factor - metabolism; Transfection
• ISSN: 2379-3708; 2379-3708
• DOI: 10.1172/jci.insight.152503

Idiopathic pulmonary fibrosis (IPF) is a fatal fibrotic lung disease associated with unremitting fibroblast activation including fibroblast-to-myofibroblast transformation (FMT), migration, resistance to apoptotic clearance, and excessive deposition of extracellular matrix (ECM) proteins in the distal lung parenchyma. Aberrant activation of lung-developmental pathways is associated with severe fibrotic lung disease; however, the mechanisms through which these pathways activate fibroblasts in IPF remain unclear. Sry-box transcription factor 9 (Sox9) is a member of the high-mobility group box family of DNA-binding transcription factors that are selectively expressed by epithelial cell progenitors to modulate branching morphogenesis during lung development. We demonstrate that Sox9 is upregulated via MAPK/PI3K-dependent signaling and by the transcription factor Wilms' tumor 1 in distal lung-resident fibroblasts in IPF. Mechanistically, using fibroblast activation assays, we demonstrate that Sox9 functions as a positive regulator of FMT, migration, survival, and ECM production. Importantly, our in vivo studies demonstrate that fibroblast-specific deletion of Sox9 is sufficient to attenuate collagen deposition and improve lung function during TGF-α-induced pulmonary fibrosis. Using a mouse model of bleomycin-induced pulmonary fibrosis, we show that myofibroblast-specific Sox9 overexpression augments fibroblast activation and pulmonary fibrosis. Thus, Sox9 functions as a profibrotic transcription factor in activating fibroblasts, illustrating the potential utility of targeting Sox9 in IPF treatment.