利用CRISPR/Cas9n系统构建Asxl2基因敲除的NIH3T3稳定细胞系

Construction of Asxl2 gene knock out stable NIH3T3 cell line with CRISPR/Cas9n system

目的利用CRISPR/Cas9n系统在NIH3T3小鼠胚胎成纤维细胞系中敲除Asxl2基因。方法设计一对靶向小鼠Asxl2基因第5个外显子的小向导RNA(sg RNA),分别克隆进p X462载体。将测序鉴定正确的重组质粒转染至NIH3T3细胞中,利用有限稀释法得到单细胞,通过培养获得单克隆细胞系。提取单克隆细胞系基因组DNA,ge-notyping PCR扩增出靶位点附近的DNA片段并测序。利用Western blot方法检测细胞株中Asxl2的敲除效果。结果成功构建靶向Asxl2的CRISPR/Cas9n重组质粒。将2个重组质粒共转染NIH3T3细胞,嘌呤霉素筛选后得到亚克隆细胞系,并且经genotyping PCR测序验证得到一株正确的单克隆细胞系。Western blot证实敲除Asxl2后,该NIH3T3细胞系中Asxl2蛋白表达缺失。结论通过这个系统得到了靶向Asxl2的CRISPR/Cas9n重组质粒及稳定敲除Asxl2的NIH3T3细胞系。

Objective To knock out Asxl2 gene in murine embryonic fibroblast cell line NIH3T3 using CRISPR/Cas9n system. Methods A pair of sgRNAs which targeted exon 5 of Asxl2 gene were designed and subcloned into the pX462 vec-tor. The recombined plasmids were verified by sequencing and transfected into NIH3T3 cell line. Single cells were isolated through serial dilutions, followed by an expansion period to obtain new monoclonal cell lines. The genomic DNA of the new monoclonal cell lines was extracted and a DNA fragment flanked the target site was amplified by genotyping PCR then se-quenced. Lastly, western blotting were applied to confirm whether Asxl2 was successfully knocked out. Results The CRIS-PR/Cas9n plasmids that targeted Asxl2 were successfully constructed. NIH3T3 cells were co-transfected with the two recom-binant constructs. After puromycin selection, subclonal cell lines were obtained and one of them was validated by genotyping PCR-sequencing. Western blotting also confirmed that Asxl2 was completely depleted in the NIH3T3 cell line. Conclu-sion CRISPR/Cas9n plasmids that targeted Asxl2 were successfully constructed therefore a Asxl2 knockout NIH3T3 stable cell line was established via this system.