Abstract
A promising emerging area for the treatment of obesity and diabetes is combinatorial hormone therapy, where single-molecule peptides are rationally designed to integrate the complementary actions of multiple endogenous metabolically-related hormones. We describe here a proof-of-concept study on developing unimolecular polypharmacy agents through the use of selection methods based on phage-displayed peptide libraries (PDL). Co-agonists of the glucagon (GCG) and GLP-1 receptors were identified from a PDL sequentially selected on GCGR- and GLP1R-overexpressing cells. After two or three rounds of selection, 7.5% of randomly picked clones were GLP1R/GCGR co-agonists, and a further 1.53% were agonists of a single receptor. The phages were sequenced and 35 corresponding peptides were synthesized. 18 peptides were potent co-agonists, 8 of whom showed EC50 ≤ 30 pM on each receptor, comparable to the best rationally designed co-agonists reported in the literature. Based on literature examples, two sequences were engineered to stabilize against dipeptidyl peptidase IV cleavage and prolong the in vivo half-life: the engineered peptides were comparably potent to the parent peptides on both receptors, highlighting the potential use of phage-derived peptides as therapeutic agents. The strategy described here appears of general value for the discovery of optimized polypharmacology paradigms across several metabolically-related hormones.
Highlights
One interesting combination is found in peptides that simultaneously activate the glucagon receptor (GCGR) and the glucagon-like peptide-1 receptor (GLP1R)[8]
Motivated by the results of Chen et al showing that an additional N-terminal Lys residue was well tolerated for GLP-1 receptor (GLP1R) agonism and offered increased resistance to DPP-IV35,43, we designed a fifth library exploring variants harboring a two amino acid extension at the GCG N-terminus
We describe a strategy for the identification of dual agonists of the GCGR and GLP1R through sequential selection of a peptide libraries (PDL) on cells expressing either receptor
Summary
One interesting combination is found in peptides that simultaneously activate the glucagon receptor (GCGR) and the glucagon-like peptide-1 receptor (GLP1R)[8]. Glucagon has anti-obesity activity by reducing food intake[19,20], and inducing thermogenesis and stimulation of growth of the brown adipose-tissue[21], but raises blood glucose by stimulating gluconeogenesis and glycogenolysis The latter effect can be counteracted by the antihyperglycemic property of GLP-1, which enhances glucose-stimulated insulin synthesis and secretion[22]. As little as one amino acid change is sufficient to switch between single- and dual-hormone agonism[10,23] These studies have been carried out by “rational design”, through an iterative cycle combining hybridization of the parent peptides with single-point mutations guided by the developing SAR: while successful and a testimony to the ingenuity of peptide medicinal chemists, this has necessarily limited the exploration of the chemical space www.nature.com/scientificreports/. The effect of multiple mutations in different parts of the molecule has rarely been explored, precluding a thorough investigation of conformational cross-talk
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