Glutaminase regulates alveolar regeneration through autophagy-YAP/TAZ in pulmonary fibrosis.

RATIONALE: Impaired alveolar regeneration is a central feature of chronic lung diseases. Type 2 alveolar epithelial cells (AT2) serve as lung stem/progenitor cells that differentiate into type 1 cells (AT1) to restore gas exchange following injury. However, the metabolic determinants governing this regenerative process remain poorly understood. OBJECTIVES: This study aimed to determine the role of glutamine metabolism via glutaminase 1 (GLS1) in regulating AT2-to-AT1 differentiation and alveolar regeneration after lung injury. METHODS: We used primary murine AT2 cells, alveolar organoids, and lineage-tracing mouse models of bleomycin-induced lung injury. The effects of AT2-specific GLS1 deletion on epithelial differentiation were assessed in vitro and in vivo. Chloroquine and bafilomycin A1, two autophagy inhibitors with distinct molecular mechanisms of action, were used for mechanistic rescue experiments. MEASUREMENTS AND MAIN RESULTS: GLS1 expression increased during AT2-to-AT1 differentiation and was accompanied by metabolic reprogramming characterized by enhanced glycolysis and increased glutamine entry into the TCA cycle. AT2-specific GLS1 deletion impaired differentiation in vitro and in vivo, resulting in defective alveolar repair and exacerbated pulmonary fibrosis. Mechanistically, GLS1 deficiency induced excessive autophagy and promoted degradation of the Hippo pathway effectors YAP and TAZ, key regulators of epithelial cell fate decisions. Inhibition of autophagy with either chloroquine or bafilomycin A1 restored YAP/TAZ levels, rescued AT2-to-AT1 differentiation, reduced fibrosis, and improved lung function. CONCLUSIONS: GLS1-mediated glutaminolysis is essential for alveolar stem/progenitor cell differentiation through regulation of autophagy and YAP/TAZ stability. Modulation of autophagy may represent a therapeutic strategy to enhance lung regeneration in fibrotic lung diseases.