Spatiotemporal GLP-1 and GIP receptor signaling and trafficking/recycling dynamics induced by selected receptor mono- and dual-agonists

Mol Metab. 2021 Jul;49:101181. doi: 10.1016/j.molmet.2021.101181. Epub 2021 Feb 6.


Objective: We assessed the spatiotemporal GLP-1 and GIP receptor signaling, trafficking, and recycling dynamics of GIPR mono-agonists, GLP-1R mono-agonists including semaglutide, and GLP-1/GIP dual-agonists MAR709 and tirzepatide.

Methods: Receptor G protein recruitment and internalization/trafficking dynamics were assessed using bioluminescence resonance energy transfer (BRET)-based technology and live-cell HILO microscopy.

Results: Relative to native and acylated GLP-1 agonists, MAR709 and tirzepatide showed preserved maximal cAMP production despite partial Gαs recruitment paralleled by diminished ligand-induced receptor internalization at both target receptors. Despite MAR709's lower internalization rate, GLP-1R co-localization with Rab11-associated recycling endosomes was not different between MAR709 and GLP-1R specific mono-agonists.

Conclusions: Our data indicated that MAR709 and tirzepatide induce unique spatiotemporal GLP-1 and GIP receptor signaling, trafficking, and recycling dynamics relative to native peptides, semaglutide, and matched mono-agonist controls. These findings support the hypothesis that the structure of GLP-1/GIP dual-agonists confer a biased agonism that, in addition to its influence on intracellular signaling, uniquely modulates receptor trafficking.

Keywords: Biased agonism; Dual-agonists; GIPR; GLP-1R; Receptor Internalization; Receptor Trafficking.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Gastric Inhibitory Polypeptide / pharmacology
  • Glucagon-Like Peptide 1 / analogs & derivatives*
  • Glucagon-Like Peptide 1 / metabolism*
  • HEK293 Cells
  • Humans
  • Ligands
  • Peptides / pharmacology
  • Receptors, Gastrointestinal Hormone / metabolism*
  • Signal Transduction / drug effects*


  • Ligands
  • Peptides
  • Receptors, Gastrointestinal Hormone
  • Gastric Inhibitory Polypeptide
  • Glucagon-Like Peptide 1
  • gastric inhibitory polypeptide receptor
  • tirzepatide