摘要目的 探讨α-1,6核心岩藻糖基转移酶(FUT8)小分子干扰RNA( siRNA)对肾小管上皮细胞转化生长因子( TGF) β-Smad2/3信号通路的影响.方法 HK-2细胞共分为6组:正常组、阴性对照组、TGF-β1组、TGF-β1加FUT8干扰组、TGF-β1加阴性对照组、FUT8干扰组.利用外源性TGF-β1激活HK-2细胞TGF-β-Smad2/3信号通路.应用siRNA技术沉默FUT8.用免疫荧光方法测定细胞表面核心岩藻糖链表达；用免疫沉淀、凝集素免疫印迹以及免疫双染的方法测定FUT8基因沉默后TGF-βⅡ型受体(TGF-βRⅡ)、TGF-β Ⅰ型受体(ALK-5)的核心岩藻糖基化变化,并检测Smad2/3蛋白表达和磷酸化(p)-Smad2/3蛋白表达及其核转位的变化.结果 与正常组及阴性对照组相比,加入5 μg/L的TGF-β1孵育HK-2细胞48 h,能显著上调TGF-βRⅡ和ALK-5蛋白表达水平(P＜0.05),导致p-Smad2/3表达水平明显升高(P＜0.05),并促使其发生核转位.HK-2细胞表面存在核心岩藻糖链表达.与正常组及阴性对照组相比,TGF-β1孵育后,TGF-βRⅡ与ALK-5两种受体的核心岩藻糖链均显著升高(P＜0.05),FUT8 siRNA能显著抑制TGF-βRⅡ与ALK-5核心岩藻糖链表达(P＜0.05),从而抑制p-Smad2/3表达升高(P＜0.05)及其核转位,但不影响TGF-βRⅡ和ALK-5的蛋白表达(P＞0.05).结论 在肾小管上皮细胞中,TGF-βRⅡ和ALK-5蛋白翻译后的核心岩藻糖基化修饰是它们发挥生物学功能所需要的,阻止TGF-βRⅡ和ALK-5的核心岩藻糖基化,能抑制TGF-β-Smad2/3信号转导通路的活化.

abstractsObjective To investigate the effect of FUT8-siRNA on transforming growth factor β (TGF-β)-Smad2/3 signalling pathway in renal tubular epithelial cells. Methods HK-2 cells were divided into six groups:normal group,negative control group,TGF-β1 group,TGF-β1 with FUT8 interference group,TGF-β1 with negative control group,FUT8 interference group.RNAi was performed to silence the expression of FUT8 gene,then immunofluorescent analysis was used to detect the expression of core fucose in the HK-2,immunoprecipitation and lectin blotting were performed to detect the core fucosylation of TGF-βR Ⅱ and ALK-5,and detect the change of Smad2/3 and p-Smad2/3 in HK-2 cells after FUT8 gene was silenced. Results Compared with the normal and negative control group,incubation with 5 μg/L TGF-β1 for 48 h could significantly up-regulate the core fucosylation of HK-2 cells,enhance the protein expression of TGF-βR Ⅱ and ALK-5 (P＜0.05),markedly increase the expression level of p-Smad 2/3 (P＜0.05) and cause it to nuclear translocation in HK-2 cells.While FUT8siRNA could inhibit the above up-regulation of TGF-βR Ⅱ and ALK-5 (P＜0.05),suppress the increase of p-Smad 2/3 (P＜0.05) and its nuclear translocation without disturbing the protein expression of TGF-βR Ⅱ and ALK-5. Conclusion FUT8-catalized core fucosylation of TGF-βR Ⅱ and ALK-5 is needed to fulfill their functions,and blocking core fucosylation of TGF-βR Ⅱ and ALK-5 leads to the inhibition of TGF-β-Smad2/3signalling pathway in HK-2 cells.