Ablation of the Renal Tubular Gluconeogenic Enzyme PCK1 Drives AKI-to-CKD Transition by Negatively Regulating the TGF-β/Smad3 Signaling Pathway

The transition from acute kidney injury (AKI) to chronic kidney disease (CKD) is characterized by progressive renal fibrosis, yet the metabolic drivers of this maladaptive repair remain inadequately defined. In this study, we investigated the role of phosphoenolpyruvate carboxykinase 1 (PCK1), the rate-limiting enzyme of gluconeogenesis, in the AKI-to-CKD transition. Analysis of human single-cell RNA sequencing (scRNA-seq) datasets revealed a profound downregulation of PCK1 in injured proximal tubule cells, which correlated with the upregulation of pro-fibrotic markers. Using a longitudinal cisplatin-induced mouse model, we demonstrated that the loss of PCK1 precedes significant collagen deposition and acts as a primary driver of fibrogenesis. Mechanistically, PCK1 deficiency triggers a metabolic shift that facilitates the activation of the TGF-β/Smad3 signaling pathway. Our functional assays established that PCK1 serves as an endogenous antagonist of Smad3, its depletion promotes Smad3 phosphorylation and nuclear translocation, leading to the loss of tubular epithelial identity. Significantly, the pharmacological or genetic restoration of PCK1 effectively blunted Smad3 activation and attenuated renal fibrosis in vivo and in vitro. These findings identify PCK1 as a critical metabolic regulator that maintains tubular homeostasis and suggest that PCK1-targeted metabolic restoration may be promising therapeutic strategies for arresting the progression of chronic kidney disease following acute injury.