Smurf2在梗阻性肾病小鼠肾小管上皮细胞转分化形成中的作用

The effect of Smurf2 on renal tubular epithelial-mesenchymal transition in obstructive nephropathic mice

目的:探讨Smad泛素化调节因子2(Smurf2)在小鼠单侧输尿管梗阻所致肾间质纤维化进展中的作用机制。方法:采用结扎雄性CD-1小鼠单侧输尿管(UUO)的方法建立肾间质纤维化动物模型,设假手术为对照组(Sham组)。术后3、7、14 d处死小鼠。用常规病理染色法观察两组小鼠肾组织形态和肾间质纤维化程度;以免疫蛋白印迹及免疫组织化学染色法检测两组小鼠肾组织中Smurf2、E-钙黏蛋白(E-cadherin)、α-平滑肌肌动蛋白(α-SMA)和纤维连接素(FN)的表达和分布。结果:与Sham组相比,UUO术后7 d小鼠出现部分肾小管扩张、萎缩和肾间质纤维化。同时,UUO术后肾组织中Smurf2、α-SMA和FN表达呈时间依赖性升高,E-cadherin表达则明显下降。并且,Smurf2蛋白主要分布于肾小管上皮细胞核内;α-SMA分布于肾小管上皮细胞和肾间质中;FN则分布于肾间质中。相关回归分析表明:UUO术后小鼠肾组织内Smurf2表达与α-SMA(r=0.765,P<0.001)和FN蛋白水平呈正相关(r=0.773,P<0.001);与E-cadherin表达呈负相关(r=-0.656,P<0.001)。结论:梗阻性肾病小鼠肾组织中Smurf2可能通过诱导肾小管EMT形成促进肾间质纤维化的进展。

Objective： To investigate the possible mechanism of Smurf2 in the progression of mice renal interstitial fibrosis induced by unilateral ureteral obstruction （UUO）. Methods： The UUO model was established through ligating left ureters of male CD-1 mice （UUO group）. At the same time,the control group were set up by sham-operation of left kidney of CD-1 male mice（sham group）. The animals were sacrified at day 3,7,14 after operation. The changes of kidney structure and the lesions of renal interstitial fibrosis were observed using HE,PAS and Masson’s trichrome staining assays. Furthermore,the expressions and distributions of Smurf2,E-cadherin,alpha-smooth muscle actin （α-SMA） and fibronectin（FN） in obstructed and normal kidneys were detected by Western blot and immunohistochemical staining assays. Results： Compared with the sham group,at day 7 after UUO operation,the atrophy and dilution of renal tubules,renal interstitial fibrogenesis were found in the obstructed kidneys. After UUO operation,the expression of Smurf2、α-SMA or FN protein was upregulated in an time-dependent manner,respectively;while the expression of E-cadherin was remarkably decreased. Moreover,the Smurf2 expression was mainly distributed in the nucelus of the renal tubular epithelial cells;while the distribution of α-SMA protein was obviously posited in renal tubular epithelial cells and renal interstitium,and the distribution of FN was in renal interstitium of the obstructed kidneys. By regression analyses,the upregulation of Smurf2 expression had positive relationship with α-SMA （r = 0.765,P 0.001） and FN （r = 0.773,P 0.01）,and negative relationship with E-cadherin （r = -0.656,P 0.001）。Conclusion： These results suggest that Smurf2 maybe act as a key in the procession of renal in terstitial fibrosis of obstructive nephropathy mice through inducing renal tubular epithelial-mesenchymal transition.