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 key tubular regulatory factors driving 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. In rodent models, we demonstrated that the loss of PCK1 precedes significant collagen deposition and acts as a primary driver of fibrogenesis. Mechanistically, PCK1 deficiency enhanced TGF-β1-induced Smad3 phosphorylation and nuclear translocation, whereas PCK1 overexpression suppressed Smad3 activation as well as the expression of fibrosis-related genes and proteins. Our functional assays supported that PCK1 serves as an endogenous negative regulator and antagonist of Smad3, its depletion releases the restraint on 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 vitro. These findings identify PCK1 as a critical metabolic regulator that maintains tubular homeostasis and suggest that PCK1-targeted modulation of Smad3 signaling may be a promising therapeutic strategy for arresting the progression of chronic kidney disease following acute injury.