Characterization of Optimized Functional-Complementary Dual Insulinotorpic Peptide rolGG

Background: Glucagon-like peptide-1 (GLP-1) and gastric inhibitory polypeptide (GIP) play a similar but complementary role in the regulation of glucose levels in islet β-cells. This study was aimed to develop a fusion peptide, which combines 4 tandem repeated GLP-1 and 4 tandem repeated GIP (4rolGG), and to investigate its therapeutic effect on type 2 diabetes using a diabetic mice model. Methods: A 4rolGG expression plasmid was constructed and expressed in BL21 (DE3). By inducting with IPTG, 4rolGG was expressed at a high level, which was confirmed by SDS-PAGE electrophoresis and Western Blotting. Subsequently, 4rolGG was purified by Ni-NTA affinity chromatography and the purity of 4rolGG was up to 90%. Result and Conclusion: After oral administration of 4rolGG for 4 weeks, streptozotocin-induced diabetic mice showed a dramatic reduction in the levels of plasma glucose, GHbA1C, TC and TG, while the insulin levels were increased significantly.