Genetic depletion or pharmacological degradation of EZH2 attenuates renal fibrosis via suppressing Notch signaling.

BACKGROUND

Enhancer of zeste homolog 2 (EZH2), a histone methyltransferase that catalyzes the trimethylation of histone H3 at lysine 27 (H3K27me3), has been implicated in promoting renal fibrogenesis. Nevertheless, its precise role and underlying mechanisms remain incompletely defined.

METHODS

To investigate the role of EZH2 in partial epithelial-mesenchymal transition (pEMT) and renal fibrosis, we utilized a mouse model with renal tubular cell-specific EZH2 deletion and administered gambogic acid (GA), a selective EZH2 degrader, following unilateral ureteral obstruction (UUO). In vitro, mouse renal epithelial cells were stimulated with TGF-β1 and treated with either EZH2-specific siRNA or GA to assess the effects on EMT and Notch1/3 signaling. In addition, chromatin immunoprecipitation (ChIP) assays were conducted to evaluate the binding of EZH2 and H3K27me3 to the promoters of Notch1 and Notch3.

RESULTS

Compared with wild-type controls, mice with tubular cell-specific EZH2 deletion exhibited significantly reduced renal fibrosis, characterized by decreased expression of fibronectin, collagen III, vimentin, and Snail, while preserving E-cadherin levels in injured kidneys. Pharmacological degradation of EZH2 with GA produced comparable antifibrotic effects. UUO injury markedly upregulated Notch1, Notch3, the Notch intracellular domain, Hes1, Hey2, and Jagged-1; these increases were significantly suppressed by either EZH2 deletion or GA treatment. Similarly, in vitro, GA or EZH2-specific siRNA inhibited the expression of Notch signaling molecules in TGF-β1-treated renal epithelial cells. Chromatin immunoprecipitation analyses revealed direct binding of EZH2 and H3K27me3 to the Notch1 and Notch3 promoters. UUO injury enhanced EZH2 binding while reducing H3K27me3 enrichment at these sites, effects reversed by GA treatment.

CONCLUSIONS

These findings demonstrate that epithelial EZH2 contributes to pEMT in renal tubular cells and promotes renal fibrosis, at least in part through activation of Notch signaling. Targeting EZH2 may hold potential as a therapeutic approach for chronic kidney disease.