G6PC Downregulation Promotes Renal Calcium Oxalate Stone Formation via Lactate-Induced SNAIL1 K206 Lactylation and Epithelial-Mesenchymal Transition.

Nephrolithiasis is increasingly prevalent worldwide. Although metabolic dysregulation has emerged as an important feature of the disease, the specific metabolic programs within tubular epithelial cells that drive stone formation remain poorly understood. Here, we use single-cell transcriptomics to profile mouse models of nephrolithiasis and identify a marked suppression of gluconeogenesis in renal proximal tubular epithelial cells, driven by downregulation of the rate-limiting enzyme glucose-6-phosphatase (G6PC) and associated with lactate accumulation. We further show that loss of G6PC or lactate accumulation is sufficient to activate TGF-β/SMAD3 signaling, driving epithelial-mesenchymal transition (EMT) and a profibrotic epithelial program associated with enhanced crystal deposition. Mechanistically, lactate induces lactylation of the transcription factor SNAIL1 at lysine 206, facilitating its nuclear localization and transcriptional activation of TGF-β. Together, these findings establish a G6PC-lactate-SNAIL1 axis linking metabolic dysregulation to epithelial remodeling during nephrolithiasis.