Integrated Yeast‐mammalian Assay System for Screening of Novel Peptides Activating Glucagon‐like Peptide‐1 Receptor

Abstract

Glucagon‐like peptide‐1 (GLP1) is a peptide hormone that is produced in intestinal L‐cells and activates GLP‐1 receptor (GLP1R), a class B G‐protein coupled receptors (GPCRs). GLP1R activation promotes insulin secretion in pancreatic β‐cells. Search of agonists activating GLP1R has been considered to be a promising approach for treating diabetes. To screen peptide agonists acting on GPCRs from peptide library, phage display system has been mainly employed. However, screening is performed based on only the binding ability to receptors, and thus it is necessary to conduct other assays for judging whether the screened peptides are biologically active or not. We have constructed a novel functional screening system that integrates a peptide secretion by yeast cells into a functional detection system by mammalian cells producing GLP1R [1]. This screening system does not require chemical synthesis, purification, and condensation of target peptides. GLP1R‐producing mammalian cells were improved by introducing inducible secretory luciferase as a reporter of signaling activation[2]. Using the constructed yeast‐mammalian assay system for functional screening, novel GLP1R agonists were found from a randomly mutagenized GLP1 library. Our yeast‐mammalian assay system can be applied to direct discovery of novel active peptides against other GPCRs.