The role of the RS1-NEDD4-YAP1 axis orchestrates epithelial-macrophage interplay in COPD

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is a heterogeneous disorder characterized by persistent airflow limitation and is a leading cause of morbidity and mortality worldwide. While cigarette smoking is the primary environmental risk factor, only a subset of smokers develops clinically significant COPD, indicating roles for genetic susceptibility and dysregulated cellular responses. Although traditionally viewed as an immune-driven inflammatory disease, recent evidence underscores the active contribution of structural cells-particularly alveolar type II epithelial cells (AT2 cells)-to immune regulation and tissue remodeling. METHODS: This study integrated single-cell transcriptomics, conditional gene knockout mouse models, organoid culture, multiplex immunofluorescence validation, and flow cytometry to investigate the role of the RS1 gene in chronic obstructive pulmonary disease (COPD). Single-cell sequencing technology revealed RS1 as a signature gene of AT2 cells. Using cigarette smoke (CS)-exposed AT2 cell-specific RS1 knockout mice and organoids as models, we elucidated the mechanisms by which RS1 regulates AT2 cells and its associated role in COPD pathogenesis through molecular experiments. RESULTS: ) and organoid models, we demonstrated that RS1-deficient AT2 cells display enhanced proliferative capacity and suppress macrophage infiltration. Mechanistically, RS1 mediates the interaction between NEDD4 and YAP1 through serine 105, while the RS1-NEDD4 interaction facilitates YAP1 dephosphorylation and nuclear translocation. Treatment with the selective NEDD4 inhibitor I3C further suppressed TGFB1 expression and macrophage infiltration. CONCLUSION: RS1 suppresses AT2 cell proliferative capacity and promotes macrophage infiltration. RS1 interacts with NEDD4 to mediate YAP1 dephosphorylation and nuclear translocation, and treatment with the selective NEDD4 inhibitor I3C further suppresses TGFB1 expression and macrophage infiltration.