Epigenetically silencing gluconeogenic enzyme PCK1 by EZH2 promotes renal tubulointerstitial fibrosis

Abstract

Renal fibrosis is the common pathological pathway of various chronic kidney diseases (CKD) in progression to the end stage of renal failure. Impaired renal gluconeogenesis has been recently identified as a hallmark of CKD. The role of gluconeogenesis in renal fibrosis is currently unknown. Through RNA sequencing and cleavage under targets and tagmentation (CUT&Tag) sequencing analysis, we found that the phosphoenolpyruvate carboxykinase 1 (PCK1), a critical enzyme in gluconeogenesis, is negatively regulated by the methyltransferase enhancer of zeste homolog 2 (EZH2) in fibrotic kidneys, which was further confirmed by quantitative PCR, CUT&Tag and Western blotting analysis in unilateral ureteral obstruction (UUO) kidneys and renal cells. We further showed that pharmaceutical inhibition or conditional knockout of EZH2 increased PCK1 expression and attenuated renal fibrosis in two other mouse models. Moreover, the concentration of lactate, a glucogenic metabolic intermediate, was increased in mouse fibrotic kidneys, which was reduced by EZH2 inhibition. We further showed that glucose production was impaired in folic acid induced nephrotic mice and restored by EZH2 inhibition as assessed by pyruvate tolerance test. Importantly, the direct anti-gluconeogenesis effect of EZH2 on renal proximal epithelial cells was shown in human HK2 cells by analysis of gluconeogenic gene expression and production of glucose or lactate. Finally, inhibition of PCK1 by 3-mercaptopropionic acid abrogated the anti-fibrotic effect of EZH2 inhibitor in UUO kidneys. We conclude that EZH2 promotes renal tubulointerstitial fibrosis through epigenetic inhibition of PCK1. Our study suggests that therapeutic restoration of the impaired renal gluconeogenesis is beneficial to CKD patients. Translational StatementRenal fibrosis is the common pathological pathway of various chronic kidney diseases (CKD) in progression to the end stage of renal failure. Impaired renal gluconeogenesis has been recently identified as a hallmark of CKD. In this study, we found that the methyltransferase EZH2 is negatively correlated with the expression of the gluconeogenic enzyme PCK1 in fibrotic kidneys. Epigenetic inhibition of PCK1 by EZH2 promotes renal tubulointerstitial fibrosis. Our study indicates that renal gluconeogenesis in CKD can be epigenetically regulated and therapeutically targeted. Epigenetic restoration of renal gluconeogenesis is a potential therapeutic strategy to treat CKD patients with tubulointerstitial fibrosis.