基于FAP基因启动子的心肌纤维化药物筛选系统的建立与验证

Establishment and verification of a drug screening system for cardiac fibrosis based on FAP gene promoter

目的建立以成纤维细胞激活蛋白(FAP)基因启动子为响应元件的新双荧光素酶报告基因系统建的心肌纤维化防治药物筛选方法。方法体外扩增小鼠FAP基因启动子片段,克隆至psiCHECK2质粒替换HSV-TK启动子,获得新的重组质粒psiCHECK2-FAP。重组质粒经限制性内切核酸酶HindⅢ消化后,进行琼脂糖凝胶电泳鉴定并纯化片段测序验证;将psiCHECK2-FAP瞬时转染至小鼠心肌成纤维细胞(MCF)培养24 h后,分别给予转化生长因子β1(TGF-β1)5μg·L^(-1),血管紧张素Ⅱ(AngⅡ)1μmol·L^(-1)或棕榈酸(PA)100μmol·L^(-1)处理0,12,24和48 h,双荧光素酶报告基因实验检测荧光素酶活性。将psiCHECK2-FAP瞬时转染至MCF细胞培养24 h后,达格列净(Dapa)1μmol·L^(-1)预处理1 h,再分别添加TGF-β1(5μg·L^(-1)),AngⅡ(1μmol·L^(-1))或PA(100μmol·L^(-1))处理24 h,双荧光素酶报告基因实验检测荧光素酶活性,Western印迹法检测MCF细胞中Ⅰ型胶原蛋白(ColⅠ)和ColⅢ的蛋白表达。结果HindⅢ将psiCHECK2-FAP切成2个片段且条带大小符合预期,测序结果与理论序列完全一致。与空白对照组相比,TGF-β1,AngⅡ和PA组均可显著增加MCF细胞中ColⅠ和ColⅢ表达(P<0.05,P<0.01);分别与TGF-β1,AngⅡ或PA组相比,Dapa干预后则显著降低ColⅠ和ColⅢ表达(P<0.05,P<0.01);与空白对照组相比,TGF-β1,AngⅡ或PA均可显著增加荧光素酶活性(P<0.05,P<0.01),24 h达最大值;分别与TGF-β1,AngⅡ或PA相比,Dapa干预后则显著降低荧光素酶活性(P<0.05,P<0.01)。结论以FAP基因启动子为响应元件的新双荧光素酶报告基因系统在MCF细胞中对促心肌纤维化因子表现出较好的敏感性,为心肌纤维化防治药物的研发提供策略。

OBJECTIVE Based on fibroblast activation protein(FAP)gene promoter as the response element,to develop a new dual luciferase reporting system for the screening of drugs related to myocardial fibrosis.METHODS The promoter fragment of mouse FAP gene was synthesized in vitro and cloned into plasmid psiCHECK2 to replace HSV-TK promoter,and then a new recombinant plasmid psiCHECK2-FAP was obtained.After the recombinant plasmid psiCHECK2-FAP was digested by restriction endonucliase HindⅢ,the product digested was identified by agar-gel electrophoresis and sequencing.After psiCHECK2-FAP was transient transfected into mouse cardiac fibroblasts(MCFs),and continued cultured for 24 h,and MCFs were treated with Ransforming growth factorβ1(TGF-β1,5μg·L^(-1))or angiotensinⅡ(AngⅡ,1μmol·L^(-1))or palmitic acid(PA,100μmol·L^(-1))for 0,12,24,48 h,respectively,the double luciferase reporter gene assay was used to detect luciferase activity;After psiCHECK2-FAP was transient transfected into MCFs,the cells were pretreated with Dapa(1μmol·L^(-1))for 1 h,and supplemented with TGF-β1(5μg·L^(-1))or AngⅡ(1μmol·L^(-1))or PA(100μmol·L^(-1)),continued treatment for 24 h,the double luciferase reporter gene assay was used to detect luciferase activity,and the expression of collagenⅠand collagenⅢprotein was detected with Western blotting.RESULTS The recombinant plasmid psiCHECK2-FAP was digested into two fragments by HindⅢwith the expected strip size,and the sequencing results were completely consistent with the theoretical sequence;Compared with control group,the collagenⅠand collagenⅢprotein expression were significantly increased by TGF-β1 or AngⅡor PA in MCFs(P<0.05,P<0.01).However,compared with TGF-β1 or AngⅡor PA group,the intervention of Dapa significantly alleviated the promoter activity of FAP gene and the expression of collagenⅠand collagenⅢprotein(P<0.05,P<0.01);Compared with control group,luciferase activity was significantly increased by TGF-β1 or AngⅡor PA(P<0.05,P<0.01),reaching the peak at 24 h.Compared with TGF-β1 or AngⅡor PA group,the intervention of Dapa significantly decreased luciferase activity(P<0.05,P<0.01).CONCLUSSION Based on the promoter of FAP gene as the response element,a noval dual luciferase reporter gene system was established and showed a good sensitivity to the promyocardial fibrosis factor in MCFs,which can provide strategies for the development of antimyocar-dial fibrosis drugs.