核干细胞因子基因siRNA表达载体的构建及鉴定

Construction and identification of a eukaryotic expression vector for the small interfering RNA targeting nucleostemin gene

目的构建针对核干细胞因子(NS)基因的小干扰RNA(siRNA)真核表达载体。方法根据GenBank提供的NS基因AY825265mRNA序列及siRNA设计原则设计siRNA,筛选得到126-144nt,199-217nt和487-505nt3个19bp片段为靶序列;合成带有BamHI、XhoI酶切位点的发夹结构寡核苷酸序列,经过退火,将此序列克隆至载体pRNAT-U6.1中构建重组表达载体;转化DH5α,提取质粒,应用PCR技术和测序方法鉴定重组克隆。转染入食管癌EC9706细胞,检测NS基因沉默情况。结果PCR筛选得到3个目的片段的阳性重组克隆,测序证实重组表达载体中插入序列与设计一致。RT-PCR和Westernblot检测显示构建的siRNA表达载体可显著降低EC9706细胞中NSmRNA和蛋白水平的表达。结论成功构建出一组针对NS基因的siRNA表达载体,为下一步NS基因的RNA干扰研究鉴定了基础。

Objective To construct a eukaryotic expression vector for the small interfering RNA （siRNA） targeting nucleostemin （NS） gene. Methods The siRNA targeting NS gene was designed according to the sequence of NS mRNA available in GenBank. Three siRNA sequences were obtained, and the corresponding cDNAs were synthesized and inserted into plasmid pRNAT-U6.1 for constructing the recombinant plasmids, which were transformed into E.coli DHSoL strain. The plasmids, after identification by PCR and DNA sequencing, were transfected into EC9706 cell line via liposome, and the mRNA and protein expressions of NS gene in the cells were determined by RT-PCR and Western blotting, respectively. Results Three recombinant plasmids were identified by PCR and sequence analysis, the results of which showed correct insertion of the designed sequences in the plasmids. RT-PCR and Western blotting showed substantially decreased mRNA and protein expressions ofNS gene in the transfected cells. Conclusion The recombinant plasmid expressing the siRNA targeting NS gene has been successfully constructed, which provides the basis for studying RNA interference of the NS gene.