中文摘要：

目的 研究N-乙酰基-丝氨酰-天门冬氨酰-赖氨酰-脯氨酸（Ac-SDKP）对血管紧张素（Ang）Ⅱ诱导的人胚肺MRC-5成纤维细胞向肌成纤维细胞分化的调节作用.方法 实验分为2部分：（1）采用不同浓度AngⅡ诱导48 h,采用100 nmol/L AngⅡ诱导不同时间点,免疫印迹法检测Ⅰ型胶原和α-平滑肌肌动蛋白（α-SMA）的表达;（2）实验分组为对照组、AngⅡ诱导组、Ac-SDKP干预组、cAMP直接激活的交换蛋白（Epac）蛋白特异性激活剂（8-Me-cAMP）干预组,免疫细胞化学染色法观察α-SMA的表达,免疫印迹法检测Ⅰ型胶原、α-SMA、血清反应因子（SRF）及其转录辅因子肌相关转录因子（MRTF）-A、Epac 1、2的表达.结果 AngⅡ能够明显诱导MRC-5细胞Ⅰ型胶原和α-SMA的表达,并具有一定的剂量和时间依赖效应.免疫细胞化学染色可见AngⅡ诱导组细胞质内出现明显的α-SMA阳性显色,同时诱导组SRF、MRTF-A、α-SMA和Ⅰ型胶原蛋白表达上调,分别是对照组的3.4、3.5、3.3、6.8倍,Epac1蛋白表达下调,差异均有统计学意义（P＜0.05）;与AngⅡ诱导组比较,8-Me-cAMP干预组和Ac-SDKP干预组胞质内α-SMA阳性显色减弱,同时SRF、MRTF-A、α-SMA和Ⅰ型胶原蛋白表达下调,Epac1蛋白表达上调,差异均有统计学意义（P＜0.05）.结论 Ac-SDKP能够通过上调Epac1蛋白抑制AngⅡ诱导人胚肺MRC-5成纤维细胞向肌成纤维细胞分化.

英文摘要：

Objective To explore the inhibition effect of N-acetyl-seryl-aspartyl-lysyl-proline （AcSDKP） on myofibroblast differentiation of MRC-5 human fetal lung fibroblasts induced by angiotensin （Ang）Ⅱ.Methods The study was divided into 2 step：（1） MRC-5 human fetal lung fibroblasts was induced for 48 h at different dose of Ang Ⅱ and at different time point by 100 nmol/L Ang Ⅱ.Then the expression of collagen type Ⅰ and α-smooth muscle actin （α-SMA） were mesaured by western blot.（2） MRC-5 human fetal lung fibroblasts were divided into 4 group：（1） control,（2） Ang Ⅱ,（3） Ang Ⅱ ＋Ac-SDKP,（4） Ang Ⅱ ＋8-Me-cAMP （a specific activator of Epac）.The α-SMA expression was observed by immnocytochemical stain.The protein expression of collagen type Ⅰ,α-SMA,serum response factor （SRF）,myocardin-related transcription factor （MRTF）-A,exchange protein directly activated by cAMP （Epac） 1,2 were measured by Westen blot.Results Myofibroblast differentiation could be induced by Ang Ⅱ from MRC-5 cells with a dose-and time-dependent manner.The up-regulation of SRF and MRTF-A were observed in MRC-5 cells induced by Ang Ⅱ and accompanied with collagen Ⅰ and α-SMA increased.Pre-treatment with 8-Me-cAMP or Ac-SDKP could attenuated all this changes induced by Ang Ⅱ,and promoted the expression of Epac1.Conclusion Ac-SDKP can inhibit the myofibroblast differentiation of MRC-5 cells induced by Ang Ⅱ via Epac 1 activating.