重组质粒pRNAT-U6.1/CFB siRNA的构建、鉴定及其对人脐静脉内皮细胞增生的影响

摘要

Background Choroidal neovascularization (CNV) is one of the causes of blindness in multiple eye diseases.Researches showed that complement system participates in the pathogenesis of CNV.Objective This study was to construct the recombinant of complement factor B-small interference RNA (CFB-siRNA) expression vector and to observe its inhibitory effect on human umbilical vein endothelial cells (ECV-304).Methods CFB gene primers were designed based on human CFB gene,and an expression vector of CFB-siRNA was constructed by inserting CFB-siRNA into pRNAT-U6.1/Neo plasmid.Recombinant plasmids were confirmed by the digestion analysis of restriction endonuclease,and all inserted sequences were verified by DNA sequencing.The recombinant pRNAT-U6.1/CFB-siRNA plasmid and the blank plasmid were transfected into ECV-304 cells in the CFB-siRNA group and blank plasmid group by electroblot,respectively,and non-transfected cells served as the normal control group.The cells were observed under the fluorescence microscope 48 hours after transfection,and the transfective efficiency was calculated.The relative expression of CFB mRNA in the cells of different groups was detected by semi-quantitative reverse transcription PCR (RT-PCR).MTT was employed to calculated the growth inhibitory rates of the cells 24,48 and 72 hours after transfection.The percentages of the cells in different cell cycles were detected by flow cytometry.Results The sequence of the target vector was identical to the designed sequence.The green fluorescence protein (GFP) was seen in both the CFB-siRNA group and the blank plasmid group.The relative expression levels of CFB mRNA were 0.07 ±0.04,0.14 ±0.02 and 0.14 ±0.03 in the CFB-siRNA group,the blank plasmid group and the normal control group,respectively,a significant difference was obtained among the three groups (F=233.05,P =0.00);the expression level of CFB mRNA in the CFB-siRNA group was significantly declined in comparison with the blank plasmid group and the normal control group (both at P＜0.05).The growth inhibitory rates of the cells were (23.45 ±0.01) ％,(33.48 ±0.02) ％ and (45.49±0.01) ％ at 24,48 and 72 hours after transfection,respectively,a significant difference was obtained among the three groups (Fgroup =212.99,P =0.00);the growth inhibitory rates in CFB-siRNA group were significantly higher than that in the blank plasmid group and normal control group (all at P＜ 0.05).The percentages of G1 phase cells were (44.4 ±0.5) ％,(25.8 ±0.4) ％ and (27.9 ± 0.6) ％ in the CFB-siRNA group,the blank plasmid group and the normal control group respectively,a significant difference was obtained among the three groups (F=58.98,P=0.00).The percentages of G1 phase and G2 phase cells in the CFB-siRNA group were significantly higher than those in the blank plasmid group and the normal control group (all at P＜0.05).Conclusions Recombinant pRNAT-U6.1/CFB siRNA inhibits the proliferation of ECV-304 cells effectively by arresting the cells in G1 intermediate phase of the growth cycle.%背景 脉络膜新生血管(CNV)是多种眼部疾病致盲的原因之一,研究发现补体系统在CNV的发病机制中起重要作用.目的 构建针对补体因子B(CFB)的小干扰RNA(siRNA)重组质粒,体外观察其对人脐静脉内皮细胞ECV-304增生的影响.方法 根据人CFB的基因序列设计引物,经PCR扩增后与质粒pRNAT-U6.1连接,得到重组质粒pRNAT-U6.1/CFB siRNA,并进行测序鉴定和PCR鉴定.ECV-304细胞株进行常规培养,用电转染技术将重组质粒或空质粒分别转染人ECV-304细胞株,分为CFB-siRNA转染组和空质粒转染组,未转染的细胞为空白对照组.细胞转染后继续培养48 h,于倒置荧光显微镜下观察绿色荧光蛋白(GFP)的表达并计算转染效率;采用半定量逆转录PCR(RT-PCR)法测定各组细胞中CFB mRNA的相对表达量;用MTT法检测各组细胞转染24、48和72 h时细胞的增生值(A)并计算生长抑制率;利用流式细胞技术检测各组细胞的生长周期变化.结果 PCR扩增的目的片段序列与CFB基因序列完全相符,ECV-304细胞转染后,倒置荧光显微镜下可见CFB-siRNA转染组和空质粒转染组的细胞中GFP呈绿色荧光.半定量RT-PCR结果显示,CFB-siRNA转染组、空质粒转染组和空白对照组的CFB mRNA相对表达量分别为0.07±0.04、0.14±0.02和0.14 ±0.03,总体比较差异有统计学意义(F=233.05,P=0.00);其中CFB-siRNA转染组CFB mRNA相对表达量明显低于空质粒转染组和空白对照组,差异均有统计学意义(均P＜0.05).MTT法检测结果显示,各组不同时间细胞增生抑制率总体比较差异有统计学意义(F分组=212.99,P=0.00);CFB-siRNA转染组细胞转染24、48、72 h后细胞增生的抑制率分别为(23.45±0.01)％、(33.48±0.02)％和(45.49±0.01)％,明显高于同时间点空质粒转染组和空白对照组,差异均有统计学意义(均P＜0.05).流式细胞仪检测结果显示,CFB-siRNA转染组、空质粒转染组和空白对照组G1期的细胞数占总细胞数的(44.4±0.5)％、(25.8±0.4)％和(27.9±0.6)％,总体比较差异有统计学意义(F=58.98,P=0.00);CFB-siRNA转染组G1期和G2期细胞所占百分比显著高于空白对照组和空质粒转染组,差异均有统计学意义(均P＜0.05).结论 重组质粒pRNAT-U6.1/CFB siRNA可通过将细胞阻滞在G1期而有效抑制人脐静脉内皮细胞的增生.