Development of the novel amylin receptor activators with nanomolar potency by peptide mutagenesis

Abstract

Amylin peptide hormone activates amylin receptors in brains and controls blood glucose and appetite. An amylin receptor activator pramlintide was developed for diabetes treatment. Currently, the amylin receptor activator with once-weekly injection has been tested for body weight reduction to treat obesity. Human amylin peptide was reported to form aggregates, while rat amylin has been shown soluble in aqueous solution. Here, multiple peptide activators for human amylin receptors were developed by introducing comprehensive mutagenesis to rat amylin peptide. The rat amylin peptide C-terminal fragment is known for interacting with human amylin receptor extracellular domain. The rat amylin peptide C-terminal fragment with eleven amino acids was used to screen for affinity-enhancing mutations. Up to twelve mutational combinations were found to significantly increase peptide affinity for amylin receptor extracellular domains by over 100-fold. Using these affinity-enhancing mutations, three representative rat amylin analogs with thirty-seven amino acids were made to test the potency increase for amylin receptor activation. All three mutated rat amylin analogs showed significant potency increases by 5- to 10-fold compared to endogenous rat amylin. These mutated peptide activators also showed higher potency for human amylin receptor activation than a clinical drug pramlintide. These amylin receptor activators developed in this study can be useful for the drug development targeting diabetes/obesity treatment.