MG132对高糖条件下肾小管上皮细胞SnoN蛋白表达及纤维化效应的影响

目的:观察蛋白酶体抑制剂MG132对高糖培养条件下肾小管上皮细胞核转录共抑制因子Sno N蛋白表达的影响,探讨MG132减轻高糖状态下肾小管纤维化病变的作用及可能机制。方法:将体外培养的NRK-52E细胞分为正常组(NG)、高糖组(HG)和不同浓度MG132预处理后高糖培养组(HG+MG132),采用免疫荧光双染的方法观察E-钙黏蛋白(E-cadherin)和α-平滑肌肌动蛋白(α-SMA)在肾小管上皮细胞中的表达和分布,用Western blotting方法检测Sno N、Samd泛素化调节因子2(Smurf2)、Arkadia、E-cadherin、α-SMA和Ⅰ型胶原(Col-Ⅰ)等目标蛋白的相对表达量。结果:与NG组相比,HG组肾小管上皮细胞E-cadherin和Sno N表达减少(P0.05),而α-SMA、Col-Ⅰ、Smurf2和Arkadia表达增多(P0.05);与HG组相比,不同浓度MG132预处理肾小管上皮细胞后高糖培养,可见肾小管上皮细胞中Sno N和E-cadherin蛋白表达显著上调(P0.05),而α-SMA和Col-Ⅰ蛋白的表达显著下调(P0.05),并且这种效应呈量效依赖性,但MG132预处理对Smurf2和Arkadia的表达无影响。结论:MG132可对抗高糖介导的肾小管上皮细胞的纤维化效应,其机制可能是通过减少Sno N蛋白的泛素化降解作用实现的。

Effects of MG132 on protein expression of SnoN and fibrosis-related in-dicators in NRK-52E cells after incubated with high concentration of glu-cose

AIM: To investigate the effects of proteasome inhibitor MG132 on the expression of SnoN in renal tubule epithelial cells incubated in high glucose, and to explore the possible mechanism and function that MG132 reduces or slows down renal tubular interstitial injury after incubated in high glucose. METHODS: The NRK-52E cells were divided into normal control group (NG), high glucose group (HG) and high glucose plus pretreatment with different doses of MG132 group (HG+MG132). The immunofluorescence staining was used to detect the protein expression of E-cadherin and α-smooth muscle actin (α-SMA) in NRK-52E cells under different conditions. The relative protein expression levels of SnoN, Smad ubiquitination regulatory factor 2 (Smurf2), Arkadia, E-cadherin, α-SMA and collagen type Ⅰ(Col-Ⅰ) were detected by Western blotting. RESULTS: Compared with NG group, the expression of E-cadherin and SnoN was decreased (P<0.05), while the expression of α-SMA, Col-Ⅰ, Smurf2 and Arkadia was increased (P<0.05). Compared with HG group, the protein expression of SnoN and E-cadherin was significantly up-regulated in HG+MG132 group (P<0.05), and the protein expression of α-SMA and Col-Ⅰ was significantly down-regulated in a dose-depended manner (P<0.05). However, no effect on the protein expression of Smurf2 and Arkadia was observed. CONCLUSION: MG132 inhibits the degradation of SnoN protein induced by high glucose, thus reducing the renal fibrosis.