目的  构建表达长效胰高血糖素样肽1（glucagon-like peptide 1，GLP-1）受体激动剂重组Exendin-4-GLP-1/IgG4(Fc)融合蛋白的质粒载体，并研究该融合蛋白的活性。方法  将编码Exendin-4-GLP-1/IgG4(Fc)的重组基因插入表达载体pOptiVEC™-TOPO^®来构建重组质粒Exendin-4-GLP-1/IgG4(Fc)-pOptiVEC™-TOPO^®。将构建的重组质粒转染CHO/DG44细胞并收获表达产物后，分别用亲和层析法和免疫印迹法对表达产物进行纯化和检测。通过胰岛素释放实验确认重组融合蛋白对INS-1细胞胰岛素分泌的影响，同时在CD1小鼠中研究该融合蛋白对血糖的调节作用。结果  转染重组质粒的CHO/DG44细胞可成功表达Exendin-4-GLP-1/IgG4(Fc)。蛋白质印迹法检测显示，纯化的表达产物的相对分子质量（M_r）与预期相符（重组融合蛋白单体和二聚体的M_r分别约为35 000和70 000）。胰岛素释放实验表明，在葡萄糖浓度恒定的情况下INS-1细胞分泌的胰岛素量随重组融合蛋白浓度的升高而增加。CD1小鼠实验显示，重组融合蛋白对链脲佐菌素诱导的糖尿病小鼠的血糖具有调节作用，Exendin-4-GLP-1/IgG4(Fc)处理的糖尿病小鼠的血糖明显低于对照糖尿病小鼠（F=3194，P＜0.01）。结论  Exendin-4-GLP-1/IgG4(Fc)具有天然GLP-1的活性，可作为GLP-1受体激动剂用于2型糖尿病的治疗。

Objective  To construct a plasmid vector expressing recombinant fusion protein Exendin-4-GLP-1/IgG4(Fc), and study activity of the fusion protein.  Methods   The gene encoding recombinant fusion protein Exendin-4-GLP-1/IgG4 (Fc) was inserted into expression vector pOptiVEC™-TOPO^® to construct recombination plasmid Exendin-4-GLP-1/IgG4(Fc)-pOptiVEC™-TOPO^®. The constructed recombination plasmid was transfected into CHO/DG44 cells. The expression product was prified by affinity chromatography and detected by Western blotting. The effect of the recombinant fusion protein on insulin secreting of INS-1 cells was determined by insulin releasing test. The regulation of the recombinant fusion protein on blood glucose was studied in CD1 mice.  Results  CHO/DG44 cells transfected with the constructed recombination plasmid successfully expressed Exendin-4-GLP-1/IgG4(Fc). Western blotting showed that relative molecular masses of the expression product were consistent with expectations. Relative molecular masses of the monomer and dime of the recombinant fusion protein were about 35 000 and 70 000, respectively. Insulin releasing test showed that amounts of insulin secreted by INS-1 cells increased with Exendin-4-GLP-1/IgG4(Fc) concentration under the same glucose concentration. CD1 mice study showed the recombinant fusion protein had regulating function on blood glucose in mice with streptozotocin-induced diabetes. Blood glucose in mice with streptozotocin-induced diabetes treated with Exendin-4-GLP-1/IgG4(Fc) was significantly lower than that in control mice with streptozotocin-induced diabetes.  Conclusion   Exendin-4-GLP-1/IgG4(Fc) has activity of  native GLP-1 and can be as a GLP-1 receptor agonist for treatment of type 2 diabetes.