PROM1 Upregulation in Renal Tubular Epithelial Cells Regulates PFKFB3-Driven Glycolysis through the mTORC1 Pathway to Improve Renal Fibrosis

Abstract

Background: Renal fibrosis is a common pathological alteration in chronic kidney disease (CKD), in which prominin 1 (PROM1) serves as a hub signature, as confirmed by a weighted gene co-expression network analysis. This study aims to investigate the precise function and mechanism of PROM1 in renal fibrosis. Methods: The in vivo and in vitro models of renal fibrosis were established by inducing overexpression of PROM1 in unilateral ureteric obstruction (UUO) mice and transforming growth factor-β (TGF-β)-treated HK-2 cells (renal tubular epithelial cells). Mammalian target of rapamycin complex 1 (mTORC1) activator MHY1485 was used in rescue experiments in vitro. Expressions of PROM1 and proteins relevant to fibrosis, the mTORC1 pathway, and glycolysis in animal and cell models were determined using western blot. Kidney fibrosis and injury, as well as 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3) location were observed following tissue staining. Lactate content and extracellular acidification rate (ECAR) were measured to assess cellular glycolysis level. Results: PROM1 was lowly expressed in kidneys and its overexpression improved kidney fibrosis of UUO mice. PROM1 overexpression rescued TGF-β-induced fibroid transformation, lactate accumulation, and ECAR increase in HK-2 cells. PROM1 overexpression reversed upregulation of fibronectin (FN), type I collagen (COL-I), plasminogen activator inhibitor-1 (PAI-1), mTOR, Raptor, Rictor, phosphorylated S6 ribosomal protein (p-S6), hexokinase 2 (HK2), and PFKFB3 in kidneys of UUO mice and TGF-β-treated HK-2 cells. MHY1485 generated opposite effects on TGF-β-treated HK-2 cells, and weakened the effects of PROM1 overexpression on suppression of the mTORC1 pathway and glycolysis. Conclusion: PROM1 upregulation in renal tubular epithelial cells regulates PFKFB3-driven glycolysis through the mTORC1 pathway to improve renal fibrosis. Our results suggest that PROM1 is a promising therapeutic target for CKD prevention and treatment.