人上皮细胞黏附分子融合蛋白真核表达载体的构建、表达及初步鉴定

Construction and expression of human EpCAM eukaryotic expression vectors and identification of their products

目的 :构建pIg EpCAM及pEGFP EpCAM真核表达载体 ,并在COS7细胞中表达。方法 :用PCR扩增EpCAMcDNA ,酶切后分别与pIg及pEGFP两种载体连接 ,用脂质体法转染COS7细胞。用免疫沉淀法检测pIg EpCAM的表达产物 ;用荧光显微镜观察EpCAM GFP的表达。结果 :DNA序列测定的结果显示 ,pIg EpCAM及pEGFP EpCAM载体的构建正确。免疫沉淀的结果显示 ,转染pIg EpCAM的COS7细胞的培养上清中含有相对分子质量 (Mr)为 6 5 0 0 0的融合蛋白 ,该蛋白与抗人IgGFc段的mAb具有良好的免疫反应性。荧光显微镜观察可见 ,转染空载体pEGFP的COS7细胞中绿色荧光均匀地分布于胞质和胞核 ;而转染pEGFP EpCAM的COS7细胞中绿色荧光主要分布于细胞表面。结论 :成功地构建了两种EpCAM的真核表达载体 ,并在COS7细胞中表达 ,为EpCAM的功能研究创造了条件 。

AIM: To construct EpCAM eukaryotic expression vectors pIg-EpCAM and pEGFP-EpCAM and to express them in COS7 cells. METHODS: EpCAM cDNA was amplified by PCR and then inserted into the pIg and pEGFP vectors respectively to construct recombinant vectors pIg-EpCAM and pEGFP-EpCAM. The two recombinant vectors were transfected into COS7 cells under the mediation of liposome. The expressed EpCAM-Ig fusion protein was detected by Western blot. The expression of EpCAM-GFP fusion protein was observed under fluorescence microscope. RESULTS: DNA sequencing demonstrated that EpCAM was correctly cloned into the two vectors. The culture supernatant of the pIg-EpCAM-transfected COS7 cells could bind effectively to mAb against human IgG Fc. Green fluorescence distributed evenly in the cytoplasm and nuclei of pEGFP-transfected COS7 cells, whereas in pEGFP-EpCAM transfected COS7 cells, green fluorescence distributed mainly on the surface of the cells. CONCLUSION: Two EpCAM eukaryotic expression vectors have been constructed and expressed successfully, which lays the foundation for functional research of EpCAM and for preparation of mAb to EpCAM.