靶向小鼠TNF-α基因RNA干扰慢病毒载体的构建及鉴定

Construction and identification of lentiviral vector harboring interference RNA targetting murine TNF-α gene

目的:构建靶向小鼠TNF-α基因的RNA干扰慢病毒载体,为RNA干扰基因治疗提供基础。方法:设计、合成3组靶向TNF-α基因的特异小干扰RNA(siRNA):siRNA1、siRNA2、siRNA3及阴性对照siRNA,体外转染小鼠巨噬细胞株RAW264.7,用real-time PCR和ELISA法检测其对经脂多糖刺激的RAW264.7细胞表达TNF-α、IL-1β、IL-6的影响。筛选出特异且抑制性高的siRNA,根据其序列设计合成寡核苷酸链,构建表达短发卡RNA(shRNA)的重组慢病毒质粒并测序,经鉴定质粒与包装质粒共转染293T细胞生产慢病毒颗粒,计算病毒颗粒滴度。结果:①siRNA1、siRNA2、siRNA3组的TNF-αmRNA相对表达量分别为0.24±0.01、0.16±0.02、0.19±0.01,与阴性对照0.95±0.02相比差别均具有统计学意义(F=531.3,P<0.001);与阴性对照相比,mRNA表达抑制率分别为74.26%、83.09%、79.93%。siRNA1、siRNA2、siRNA3及阴性对照组的IL-1βmRNA或IL-6 mRNA相对表达量之间差别无统计学意义(F=0.981,P=0.980 7>0.05;F=0.739,P=0.586 7>0.05)。②siRNA1、siRNA2、siRNA3的TNF-α蛋白表达分别为(23.95±1.21)、(17.27±1.46)、(19.07±1.57)ng/ml与阴性对照的(35.37±2.93)ng/ml相比,差别均具有统计学意义(F=18.1,P=0.000 6<0.001);与阴性对照相比,TNF-α蛋白表达抑制率分别为32.29%、51.16%、46.08%。③以siRNA2序列设计、合成寡核苷酸链,构建重组慢病毒穿梭质粒,其PCR产物电泳结果为343 bp,空载体PCR产物306 bp;DNA测序显示pGCSIL-GFP-shRNA测序反应中断,但已显示部分插入序列。④转染后的293T细胞,生长良好,荧光表达强,慢病毒滴度为2×106TU/μl。结论:靶向小鼠TNF-α基因RNAi慢病毒载体构建成功。

Objective：To construct recombinant lentiviral vectors harboring interference RNA （ RNAi ） targetting murine TNF-αgene,so as to lay the foundation on the RNAi gene therapy.Methods： Three small interfering RNA （ siRNA） sequences targeting murine TNF-αgene （ siRNA1,siRNA2,siRNA3） and negative-control siRNA were designed and synthesized.The inhibition effects of siRNAs on TNF-α,IL-1βand IL-6 secretion of LPS-stimulated RAW264.7 macrophages were observed using real-time PCR and ELISA methods.DNA oligo was designed and synthesized according to the most effective siRNA 2 sequence.The recombinant lentiviral shuttle plasmid expressing short hairpin RNA （ shRNA） was constructed and sequenced.The lentiviral shuttle plasmids with packaging plasmids were transfected into 293T cells to produce lentiviral particles.Results： ①The TNF-αmRNA relative expression levels of siRNA1, siRNA2 and siRNA3 were 0.24±0.01,0.16±0.02,0.19±0.01 respectively,significantly lower than that of negative control （0.95± 0.02） （F=531.3,P〈0.001）.The inhibition rates at mRNA level were 74.26%,83.09%,79.93%,respectively comparing with negative control.No significance was observed in IL-1βor IL-6 mRNA relative expression change after TNF-αsiRNA transfection （ P〉0.05）.②The TNF-αprotein expression levels of siRNA1,siRNA2 and siRNA3 were （23.95±1.21）,（17.27±1.46）,（19.07± 1.57）ng/ml respectively,significantly lower than that of negative control （35.37±2.93）ng/ml （F=18.1,P=0.000 6〈0.001）.The inhibition rates of protein expression were 32.29%, 51.16%, 46.08%, respectively comparing with negative control.③The PCR product electrophoresis showed that recombinant vectors yielded 343 bp fragments,non-constructed vectors yielded 306 bp fragments.DNA sequencing partially showed insertion sequence.④Lentiviral particles were obtained by transfecting 293T cells with recombinant lentiviral shuttle plasmids and lentiviral packaging plasmids.Cells grew well during virus production with strong fluorescence expression.The titer of concentrated virus was 2×10^6 TU/μl.Conclusion：The lentiviral vector harboring RNAi targeting murine TNF-αgene has been successfully constructed.