Hydrostatic pressure regulates glutamine metabolism to promote bladder fibroblast activation via the Piezo1/YAP1/GLS1 axis.

backgroundBladder outlet obstruction (BOO), initiated by abnormal mechanical stress, leads to progressive bladder fibrosis and functional decompensation. Abnormal mechanical stress plays a key role in the pathogenesis of various diseases, including fibrosis. However, the mechanisms through which BOO-induced abnormal mechanical stress drives bladder fibrosis remain poorly understood. Recent studies have highlighted that Yes-associated protein 1 (YAP1) serves as a critical integrator of mechanical signals and metabolic alterations. Abnormal mechanical stress can promote disease progression by regulating metabolic enzymes such as glutaminase 1 (GLS1) through YAP1. Alterations in cellular behavior and disease progression induced by abnormal mechanical stress are closely linked to metabolic reprogramming. Targeting this metabolic reprogramming may effectively counteract the resulting cellular alterations and disease progression.

methodsKEGG pathway enrichment was performed using RNA-seq data from a rat BOO model, and YAP1 expression was examined in human and rat bladder tissues. Fibroblasts were cultured under high hydrostatic pressure (HHP) to mimic BOO-induced stress, and YAP1 nuclear translocation and GLS1 expression were assessed by immunofluorescence and western blotting. Fibroblast proliferation, migration, and activation were measured via functional assays and fibrotic protein expression. To clarify the roles of Piezo1 and YAP1, we performed siRNA, inhibitor, and rescue experiments and evaluated their effects on GLS1, glutamine metabolism, and fibroblast activation. In vivo, bladder function and histology were assessed following GLS1 inhibition in BOO rats.

resultsYAP1 expression was significantly increased in human and rat bladders with BOO. HHP enhanced nuclear translocation of YAP1 and upregulated GLS1. HHP stimulation also promoted fibroblast proliferation, migration, and activation. Under HHP, Piezo1 acted as the upstream mechanotransducer that activated YAP1, which in turn induced GLS1 expression. Inhibition of Piezo1 or YAP1 reduced GLS1 expression, and blockade of this axis suppressed fibroblast activation in vitro. HHP-induced fibroblast activation relied on GLS1-driven glutamine metabolic reprogramming, and pharmacological blockade of GLS1 effectively attenuated fibrosis and improved bladder function in BOO rats.

conclusionsThis study identifies a Piezo1/YAP1/GLS1 axis linking mechanical stress to metabolic reprogramming and fibroblast activation in BOO, which may serve as a therapeutic target to prevent fibrosis and preserve bladder function.