中文摘要：

目的研究胰岛素诱导大鼠血管平滑肌细胞（vascular smooth muscle cell,VSMC）转录因子激活蛋白-1（activator protein 1,AP-1）表达下调对VSMC表型转换标志蛋白α肌动蛋白（alpha smooth muscle actin,SM-α）表达调控及细胞增殖的影响。方法流式细胞术检测不同浓度（0、25、50、100、125 nmol/L）的胰岛素刺激VSMC 24 h后的细胞周期。设计AP-1表达质粒载体,转染至血管平滑肌细胞（vascular smooth muscle cell,VSMC）。分为4组：空白对照组、胰岛素实验组、AP-1表达载体组、胰岛素＋AP-1表达载体组。分别采用Western blot、RT-PCR检测AP-1蛋白及SM-α蛋白的表达及mRNA水平。结果细胞周期分布结果显示,不同浓度的胰岛素刺激VSMC 24 h后,VSMC的S期百分比升高至峰值后开始下降[（23.49±1.17）%、（28.08±0.68）%、（30.44±1.77）%、（47.47±0.88）%、（46.23±1.65）%,P〈0.05],100 nmol/L的胰岛素刺激VSMC 24 h后,VSMC的S期百分比达到峰值（47.47±0.88）。RT-PCR及Western blot检测结果显示,胰岛素刺激VSMC可下调AP-1[（0.47±0.09）、（0.46±0.14）,P〈0.05]及抑制SM-α的表达[（0.41±0.03）、（0.32±0.03）,P〈0.05]。结论胰岛素能下调转录因子AP-1表达,进而抑制表型转换标志蛋白SM-α的表达,诱导VSMC发生增殖。

英文摘要：

Objective To determine the effect of down-regulating insulin-induced transcription activator protein 1（ AP-1） on the expression regulation of alpha smooth muscle actin（ SM-α） and cell proliferation in rat vascular smooth muscle cells（ VSMCs）. Methods Flow cytometry was employed to analyze the cell cycle of VSMCs after treatment of 0,25,50,100 and 125 nmol / L insulin for 24 h. Plasmid vector encoding AP-1 gene was designed and then transfected into VSMCs. Meanwhile there were 4 groups of VSMCs,that is,control,insulin treatment,AP-1 expression vector,and insulin ＋ AP-1 expression vector group. The expression of AP-1 and SM-α at protein and mRNA levels was detected by Western blotting and RT-PCR respectively. Results Flow cytometry results showed that after stimulating of insulin at different concentrations（ 0,25,50,100 and 125 nmol / L）,the percentage of the cells at S phase was risen to a peak and then declined after rising [（ 23. 49 ± 1. 17） %,（ 28. 08 ± 0. 68） %,（ 30. 44 ± 1. 77） %,（ 47. 47 ±0. 88） % and（ 46. 23 ± 1. 65） %,P〈0. 05]. The peak of the amount of S phase cells were the VSMCs treated by 100 nmol / L insulin [（ 47. 47 ± 0. 88） %]. Western blotting and RT-PCR showed that insulin down-regulated the expression of AP-1（ 0. 46 ± 0. 14 and 0. 47 ± 0. 09）（ P〈0. 05） and suppressed the expression of SM-α（ 0. 32 ± 0. 03 and 0. 41 ± 0. 03）（ P〈0. 05） by stimulating VSMCs. Conclusion Insulin suppresses the expression of SM-α by down-regulating the expression of AP-1 to induce the proliferation of VSMCs.