Cdc42相关蛋白4通过极性蛋白6参与肾间质纤维化

Involvement of Cdc42-interacting protein 4 in renal interstitial fibrosis through Par6

目的探讨Cdc42相关蛋白4对闭合素表达的影响及与极性蛋白6之间的相互作用。方法体内实验用单侧输尿管结扎术建立小鼠的。肾脏纤维化模型，根据Masson染色观察肾脏纤维化，用免疫组织化学法观察Cdc42相关蛋白4的表达及分布。体外实验用转化生长因子81诱导大鼠近端肾小管上皮细胞向间质细胞转分化。瞬时转染pcDNA4．0／Cdc42相关蛋白4质粒至NRK52E细胞。Westernblot法检测相关蛋白的表达。免疫沉淀法检测Cdc42相关蛋白4与极性蛋白6的相互作用。结果Cdc42相关蛋白4在纤维化的肾组织中表达上调，主要分布于肾小管上皮细胞。高表达Cdc42相关蛋白4与转化生长因子81刺激后的细胞相关蛋白表达量的改变一致，且均存在Cdc42相关蛋白4与极性蛋白6的相互作用。结论Cdc42相关蛋白4可能通过与极性蛋白6相互作用，调节闭合素的表达，参与肾间质纤维化。

Objective To investigate the expression and distribution of CIP4 in renal fibrotic tissue and in transforming growth factorl31 （TGF-131）-induced epithelial-mesenehymal transition（EMT） model of NRK52E cell line, the effect o{ CIP4 over-expression in NRK52E cells, and interaction be- tween CIP4 and polarity protein Par6. Methods In vivo, the models of renal fibrosis were induced by unilateral ureteral obstruction in BALB/c mice. Masson staining was used to evaluate severity of renal tissue fibrosis, and the expression and distribution of CIP4 were detected by using immunohistochemis- try. In vitro,the EMT model of NRK52E cell line was induced by TGF-~I（10 ng/ml） for 72 h. CIP4 plasmid was transiently transfected into NRK52E cells by lipofectamine 2000. Western blot was used to observe the expression of Par6 tight junction protein occluding, CIP4 and a-SMA. Interaction between CIP4 and Par6 was analyzed by using immunoprecipitation. Results CIP4 expression was increased in unilateral ureteral obstruction group as compared with sham group, and CIP4 was mainly distributed in renal tubular epithelia. In vitro, the expression of a-SMA and CIP4 was increased in NRK52E cells stimulated with TGF-β1 for 72 h,the expression of occludin was decreased,but no significant change in Par6 was found. In NRK52E cells with CIP4 over-expression, occludin expression was decreased, while the expression of α-SMA was increased. Interaction between CIP4 and Par6 was detected in TGF-β1 and CIP4 over-expression NRK52E cells. Conclusions CIP4 may be involved in the renal interstitial fibrosis by interacting with Par6 and regulating the occluding expression.