Rational design of a GLP-1/GIP/Gcg receptor triagonist to correct hyperglycemia, obesity and diabetic nephropathy in rodent animals

Aims: To design and screen a potent GLP-1/GIP/Gcg receptors triagonist with therapeutic potential in rodent animals with diabetes and obesity. Main methods: First, we obtained a 12-mer dual GIP/Gcg receptor agonist from a large combinatorial peptide library via high-throughput screening technique and then fused to the Exendin (9–39) to generate a potent GLP-1/GIP/Gcg triagonist. Further site fatty chain modification was performed to improve the druggability via enhancing in vivo stability and cyclic half-life. In vitro signaling and functional assays in cell lines expressing each receptor and in vivo efficacy evaluation in rodent model animals with hyperglycemia and obesity were all carefully performed. Key findings: We screened and obtained a potent GLP-1/GIP/Gcg triagonist, termed XFL0, which promotes in vitro GLP-1, GIP, Gcg receptor activation comparable to native GLP-1, GIP and glucagon, respectively. Site-specific fatty acid modification significantly enhanced plasma stability of XFL0 and exhibited no obvious impact on receptor activation. The selected XFL0 conjugates termed XFL6, showed glucose-dependent insulin secretion and improved glucose tolerance by acting on all GLP-1, GIP and Gcg receptors in gene-deficient mice of which the effects were all significantly greater than any single receptor agonist. After chronic treatment in rodent animals with diabetes and obesity, XFL6 potently decreased body weight and food intake, ameliorated the hyperglycemia and hemoglobin A1c levels as well as the lipid metabolism and diabetic nephropathy related disorders. Significance: XFL6, as a novel GLP-1/GIP/Gcg receptor triagonist, held potential to deliver outstanding improvement in correcting hyperglycemia, obesity and diabetic nephropathy.