[EZH2 promotes development and progression of diabetic nephropathy]

Objective To investigate the effect of enhancer of zeste 2 polycomb repressive complex 2 subunit (EZH2) on the development of renal tubular epithelial-mesenchymal transformation (EMT) and diabetic nephropathy (DN). Methods Mouse model of type 1 diabetic nephropathy (T1DN) was established by intraperitoneal injection of streptozotocin (STZ) (55 mg/kg) and randomly divided into normal control and diabetic group. The mice were killed, and their biochemical indexes (blood glucose, creatinine, microalbumin and total protein in urine) of blood and urine were recorded. The kidneys were subjected to HE and Masson staining to observe morphological changes. Immunohistochemical staining was used to observe the expression and localization of type IV collagen (Col4) and EZH2. The mRNA and protein expressions of E-cadherin, α-smooth muscle actin (α-SMA), Col4 and EZH2 were detected by real-time fluorescent quantitative PCR and Western blotting. Rat renal tubular epithelial cells were cultured with high glucose and transfected with small interfering RNA (siRNA) of EZH2.The protein levels of E-cadherin, α-SMA, Col4 and EZH2 were detected by Western blot analysis. Results Compared with the normal group, blood glucose, serum creatinine, microalbuminuria and total urine protein significantly increased in the diabetic group. The mRNA and protein levels of E-cadherin, α-SMA, Col4 and EZH2 went up; the tubular lumen collapsed; the basement membrane of glomerulus thickened and there was a large amount of collagen deposition in the renal interstitium. Compared with normal sugar, high glucose stimulation promoted EMT and significantly up-regulated EZH2 expression. Compared with high glucose group, the transfection of EZH2 siRNA in high glucose inhibited EMT. Conclusion EZH2 can effectively promote the EMT process of renal tubular epithelial cells and may participate in the occurrence and development of DN through this role.