siRNA干扰绵羊胚胎成纤维细胞Lig4基因增加同源重组载体重连修复效率

Increasing the efficiency of homologous recombination vector-mediated end joining repair by inhibition of Lig4 gene using si RNA in sheep embryo fibroblasts

在动物细胞中，抑制非同源末端连接（Non-homologous end joining, NHEJ）修复途径，可以提高同源重组（Homologous recombination, HR）修复基因组双链断裂（Double-strand brakes, DSBs）的发生概率。为了提高绵羊胚胎成纤维细胞的 HR 效率，针对 NHEJ 修复途径中的关键因子 Lig4（DNA ligase 4）基因，本文设计合成4个具有靶向性的 siRNA（Small interfering RNA）。绵羊胚胎成纤维细胞经电转染导入 siRNA，通过实时荧光定量PCR（qRT-PCR）和 Western blotting 检测，筛选出有效抑制 Lig4基因表达的2个 siRNA。应用质粒重连法检测HR 修复效率，将 I-SceⅠ酶线性化的 HR 质粒和 siRNA 共转染绵羊胚胎成纤维细胞，经72 h 培养及流式细胞仪检测，与对照组细胞比较，结果表明 HR 质粒重连效率提高了3~4倍。瞬间干扰 Lig4基因的表达可提高 HR质粒重连效率，为改善绵羊胚胎成纤维细胞基因打靶效率提供理论基础。

In animal cells, inhibition of non-homologous end joining （NHEJ） pathway improves the efficiency of＆nbsp;homologous recombination （HR）-mediated double-strand brakes （DSBs） repair. To improve the efficiency of HR in sheep embryo fibroblasts, the NHEJ key molecule DNA ligase 4 （Lig4） was suppressed by siRNA interference. Four pairs of siRNA targeting Lig4 were designed and chemically synthesized. These siRNA were electro-transferred into sheep embryo fibroblasts respectively. Compared with the control groups, two pairs of siRNA were identified to ef-fectively inhibit the expression of sheep Lig4 gene by qRT-PCR and Western blotting. The plasmid rejoining assay was adopted for examining the efficiency of HR-mediated DSB repair. I-SceⅠ endonuclease linearized vector and siRNA were co-transfected into sheep embryo fibroblasts. Flow cytometry analysis of cells after transfection for 72 h showed that suppression of Lig4 using siRNAs increased the rejoining efficiency of HR vector by 3-4 times compared with the control groups. Therefore, enhanced HR vector rejoining frequency by instant inhabition of Lig4 gene pro-vides theoretical basis for improving gene targeting efficiency of sheep embryo fibroblasts.