血管紧张素Ⅱ1型受体表达对高糖诱导大鼠肾小管上皮细胞损伤的影响

Effect of angiotensin Ⅱ type 1 receptor on injury of renal tubular epithelial cells induced by high glucose

目的探讨血管紧张素Ⅱ1型受体(AT1R)在高糖诱导大鼠肾小管上皮细胞损伤中的作用及分子机制。方法体外培养大鼠肾小管上皮细胞,分为正常对照组、高糖组、高糖+血管紧张素Ⅱ1型受体小干扰RNA组、高糖+小干扰RNA阴性对照组。采用免疫印迹法检测受体AT1R、脂联素受体1(AdipoR1),炎性因子核转录因子(NF-κB)、单核细胞趋化因子1(MCP-1)、巨噬细胞炎症蛋白1α(MIP-1)及纤维化标记物α-肌动蛋白(α-SMA)、纤维结合蛋白(FN)的表达;采用免疫沉淀法检测AT1R-AdipoR1二聚化在肾小管上皮细胞中的形成,共聚焦显微镜下观察AT1R、AdipoR1在肾小管上皮细胞中的共定位关系。结果研究发现,在高糖刺激下,大鼠肾小管上皮细胞中AdipoR1表达无改变,AT1R表达明显增加(P<0.05);炎性因子NF-κB、MCP-1、MIP-1α表达显著上调(均P<0.05);纤维化标记物α-SMA、FN表达显著升高(均P<0.01)。研究还发现,大鼠正常肾小管上皮细胞中存在AdipoR1-AT1R二聚化,且在高糖刺激下AdipoR1-AT1R二聚体表达较正常对照组明显升高。在转染血管紧张素Ⅱ1型受体小干扰RNA后,AT1R-AdipoR1二聚化明显减少,且明显抑制AT1R表达(P<0.05),并使肾小管上皮细胞炎性因子NF-κB、MCP-1、MIP-1α表达显著下调(均P<0.05),使纤维化标记物α-SMA、FN表达明显降低(均P<0.05)。结论高糖刺激下,AT1 R通过促进AT1 R-AdipoR1二聚化,介导肾小管上皮细胞炎性损伤及诱导肾小管上皮细胞凋亡,促进其纤维化的发生发展。

Objective To investigate the effect and possible mechanisms of angiotensin Ⅱ type1 receptor（AT1 R） on injury of renal tubular epithelial cells induced by high glucose. Methods The expression of AT1 R,AdipoR1,NF-κB,MCP-1,MIP-1 α,α-SMA,FN were detected by using western blot. The colocalization of AT1 R and AdipoR1 was detected by confocal microscopy. The dimerization of AT1 R and AdipoR1 was detected by immunoprecipitation. Results Compared with control group,the expression of AdipoR1 had no significant change and the expression of AT1 R was increased in rat renal tubular epithelial cells induced by high glucose. The expression of inflammatory factors as NF-κB,MCP-1 and MIP-1 α was increased in rat renal tubular epithelial cells stimulated with high glucose.Compared with control group,the expression of α-SMA and FN was increased in rat renal tubular epithelial cells stimulated with high glucose. The dimerization of AT1 R and AdipoR1 was formed in the rat renal tubular epithelial cells. And the AT1 R-adipoR1 dimerization was increased in the rat renal tubular epithelial cells induced by high glucose. Knockdown of AT1 R by siRNA inhibited the demerization of AT1 R-adipoR1,reduced the expression of inflammatory factors as NF-κB,MCP-1 and MIP-1 α,decreased the expression of α-SMA and FN in rat renal tubular epithelial cells induced by high glucose.Conclusions AT1 R promotes the inflammation and fibrosis of renal tubular epithelial cells induced by high glucose through dimerization of AT1 R-adipoR1.