摘要:
Objective To observe the effect of costimulatory molecule B7-1 on cytoskeleton rearrangement in mouse podocytes induced by angiotensin Ⅱ (Ang Ⅱ),and to study the underlying molecular mechanism of B7-1 in the pathological changes of podocytes.Methods All cultivation of conditionally immortalized mouse podocytes (MPC) in vitro were divided into the following groups:normal control group,CTLA-4 group,Ang Ⅱ group (10-6 mmol/L 12 h,24 h;10-8 mmol/L 12 h,24 h) and CTLA-4 with Ang Ⅱ group.Transfect B7-1 RNA interference fragment (siRNA) to the mature podocytes,and then restimulated by Ang Ⅱ (10-6 mmol/L 12 h),the change of podocyte cytoskeleton after Ang Ⅱ stimulation were observed.The expression of B7-1 in each group was assayed by flow cytometry and Western blotting.The nephrin and p-nephrin protein levels in the four groups were also analyzed by Western blotting.At the same time,the podocyte cytoskeleton distribution as indicated by F-actin was observed by fluorescence microscopy.Results Flow cytometry and Western blotting showed that B7-1 was not expressed in the normal control group.Ang Ⅱ showed a concentration and time dependent induction of B7-1 expression in mouse podocytes (P < 0.05).Western blotting indicated that Ang Ⅱ induced B7-1 protein expression (P < 0.05).Expression of nephrin and p-nephrin was significantly down-regulated by Ang Ⅱ (P < 0.05).Compared with the normal control group,the expression of podocyte protein nephrin and p-nephrin in Ang Ⅱ stimulation group was significantly reduced (P < 0.05).Using FITC phalloidin fluorescence staining showed that CTLA-4+Ang Ⅱ stimulation group cytoskeleton rearrangement was improved significantly and F-actin recombinant score (mCFS) decreased compared with Ang Ⅱ group (P < 0.05),suggesting that Ang Ⅱ led to the disorder of the podocytes cytoskeleton and the destruction of the cytoskeleton of podocytes by Ang Ⅱ could be improved after B7-1 blocking.Compared with the Ang Ⅱ stimulation,transfection of B7-1 siRNA + Ang Ⅱ stimulation group improved F-actin cytoskeletal rearrangement,and mCFS also decreased significantly (P < 0.05),suggesting that transfection of B7-1 siRNA might improve the damage of Ang Ⅱ on podocytes cytoskeleton.Conclusions B7-1 participates in the process of cytoskeleton reconstruction and plays an important role in the pathological changes of podocytes.%目的 观察共刺激分子B7-1对血管紧张素Ⅱ(AngⅡ)诱导的小鼠足细胞骨架重排的影响,探讨B7-1在足细胞病变中的作用以及可能的分子机制.方法 体外培养条件永生性小鼠足细胞(MPC),分组如下:正常对照组、AngⅡ刺激组、CTLA-4(B7-1封闭剂)干预组和CTLA-4干预+AngⅡ刺激组.转染B7-1 RNA干扰片段(siRNA)至分化成熟的足细胞,再予10-6 mmol/L AngⅡ刺激12h,观察沉默B7-1基因对AngⅡ刺激下足细胞骨架改变的影响.用流式细胞术检测足细胞B7-1表达;Western印迹法检测足细胞B7-1、nephrin、p-nephrin分子的表达;异硫氰酸荧光素(FITC)-鬼笔环肽荧光染色法观察足细胞骨架蛋白F-actin表达.结果 流式细胞术和Western印迹结果显示,正常对照组足细胞B7-1无表达,AngⅡ刺激组足细胞B7-1表达明显增加,且随AngⅡ刺激浓度增加和时间延长B7-1表达增加(均P<0.05).与正常对照组比较,AngⅡ刺激组足细胞nephrin和p-nephrin表达量明显下调(均P<0.05).FITC-鬼笔环肽荧光染色结果显示,与AngⅡ刺激组比较,CTLA-4干预+AngⅡ刺激组细胞骨架重排改善,F-actin重组评分(mCFS)明显降低(P<0.05),提示封闭B7-1可改善AngⅡ对足细胞细胞骨架的破坏;与AngⅡ刺激组比较,转染B7-1 siRNA+AngⅡ刺激组细胞骨架重排改善,F-actin mCFS亦明显降低(P<0.05),提示转染B7-1 siRNA亦可改善AngⅡ对足细胞细胞骨架的破坏.结论 B7-1参与足细胞骨架重排过程,在足细胞损伤中起重要作用.