# Design, synthesis, and characterization of Gs- and Gq-biased agonists of the Glucagon-like Peptide-1 Receptor (GLP-1R)

> **NIH NIH F32** · UNIVERSITY OF WISCONSIN-MADISON · 2022 · $26,101

## Abstract

Project Summary/Abstract
 Cardiovascular disease (CVD) is the major cause of death in the United Stand and is particularly
prevalent in patients with type-2 diabetes mellitus (T2DM). Recently, agonists of the glucagon-like peptide-1
receptor (GLP-1R), a G protein-coupled receptor (GPCR) and common target for the treatment of T2DM, have
shown promising cardiovascular benefits including a significant reduction in CVD-associated morbidity and
mortality. However, broader clinical trials of approved GLP-1R agonists, many of which are synthetic peptides,
have yielded mixed results. Thus, there is a critical need to understand the underlying mechanism driving the
different modes of action for the same class of reagents to design more targeted and effective therapeutics.
 Notably, many synthetic peptide agonists of GLP-1R have demonstrated biased agonism, i.e., a ligand
drives preference for certain signaling pathways relative to the endogenous agonist, GLP-1. This phenomenon
is seen in many other GPCRs. For example, the Gellman lab replaced α residues with β residues on the N-
terminus of the PTH peptide and observed a G-protein bias when treating cells expressing the PTH receptor.
 I propose to build on this strategy to develop novel synthetic peptide agonists of GLP-1R that are biased
for the Gs and Gq pathways as tools to better understand GLP-1R signaling. I will design and synthesize α/β-
peptides analogies of GLP-1 by replacing the first eight amino acid residues at the N-terminus, individually, with
β residues. Cell-based assays will be performed to measure cAMP production (Gs), calcium mobilization (Gq),
and β-arrestin-1, 2 recruitment, which represent the major signaling pathways of GLP-1R, to characterize the
signaling profile and determine their biased relative to GLP-1.
 Next, I hypothesize that the biased activation of GLP-1R is the result of unique post-translational
modifications (PTMs) and protein-protein interactions that arise after peptide binding and that downstream
expression and phosphorylation of intracellular proteins is altered as a result. To test this hypothesis, I will use
mass spectrometry (MS)-based proteomics to characterize the PTMs of purified GLP-1R that arise after
treatment with the Gs and Gq biased peptides as well as β-arrestin-1 and -2 biased peptides previously
developed in the Gellman group. A second MS assay will be performed after co-immunoprecipitation of the
receptor to investigate unique receptor-protein interactions that arise after peptide binding. Finally, a third MS
assay will access downstream changes in protein expression and phosphorylation for an in-depth understanding
of the signal transduction produced by biased agonist binding. The results of this proposal will help elucidate the
mechanisms driving the signal transduction of GPCRs and aid in the development of safer, more effective
therapeutics.

## Key facts

- **NIH application ID:** 10388640
- **Project number:** 1F32HL162374-01
- **Recipient organization:** UNIVERSITY OF WISCONSIN-MADISON
- **Principal Investigator:** Kyle A Brown
- **Activity code:** F32 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $26,101
- **Award type:** 1
- **Project period:** 2022-08-01 → 2022-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10388640

## Citation

> US National Institutes of Health, RePORTER application 10388640, Design, synthesis, and characterization of Gs- and Gq-biased agonists of the Glucagon-like Peptide-1 Receptor (GLP-1R) (1F32HL162374-01). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10388640. Licensed CC0.

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