Agonist-induced membrane nanodomain clustering drives GLP-1 receptor responses in pancreatic beta cells.

Teresa Buenaventura,Zekun Lyu,Guy A Rutter,Hannah Norman,Stephen R Bloom,Stavroula Bitsi,Ben Jones,Thomas Burgoyne,Jak Grimes,Andrey S Klymchenko,Ivan R Corrêa,Davide Calebiro,Asuka Inoue,Abigail Walker,William E Laughlin ,Emma Rose Mcglone ,Affiong I Oqua ,Zsombor Köszegi ,Aylin Hanyaloglu ,Alejandra Tomás

doi:10.1371/journal.pbio.3000097

Abstract

The glucagon-like peptide-1 receptor (GLP-1R), a key pharmacological target in type 2 diabetes (T2D) and obesity, undergoes rapid endocytosis after stimulation by endogenous and therapeutic agonists. We have previously highlighted the relevance of this process in fine-tuning GLP-1R responses in pancreatic beta cells to control insulin secretion. In the present study, we demonstrate an important role for the translocation of active GLP-1Rs into liquid-ordered plasma membrane nanodomains, which act as hotspots for optimal coordination of intracellular signaling and clathrin-mediated endocytosis. This process is dynamically regulated by agonist binding through palmitoylation of the GLP-1R at its carboxyl-terminal tail. Biased GLP-1R agonists and small molecule allosteric modulation both influence GLP-1R palmitoylation, clustering, nanodomain signaling, and internalization. Downstream effects on insulin secretion from pancreatic beta cells indicate that these processes are relevant to GLP-1R physiological actions and might be therapeutically targetable.

Highlights

G protein–coupled receptors (GPCRs), the largest membrane receptor family in eukaryotes [1], are integral membrane proteins, and, as such, both their physical organization and their signaling properties are modulated by the lipid composition of the surrounding membrane [2,3]
To determine the influence of agonist binding upon glucagon-like peptide-1 receptor (GLP-1R) raft partitioning in pancreatic beta cells, we measured SNAP-GLP-1R levels in purified detergent-resistant fractions (DRFs) and detergent-soluble fractions (DSFs) from total membrane preparations of mouse insulinoma MIN6B1 cells [31] stably expressing human GLP-1R SNAP-tagged at the extracellular N terminus (MIN6B1 SNAP-GLP-1R cells) [21]
In cells expressing SNAP-GLP-1R labeled with the long-lived lanthanide Forster resonance energy transfer (FRET) donor Lumi4-Tb, timeresolved FRET (TR-FRET) was increased upon exendin-4 addition (S1E Fig), indicating relative movement between the Lumi4-Tb-labeled GLP-1R extracellular domain and the plasma membrane, possibly reflecting the closure of the receptor extracellular domain upon ligand binding, as recently suggested [36]

Summary

Introduction

G protein–coupled receptors (GPCRs), the largest membrane receptor family in eukaryotes [1], are integral membrane proteins, and, as such, both their physical organization and their signaling properties are modulated by the lipid composition of the surrounding membrane [2,3]. The localization of GPCRs to dynamic membrane nanodomains has been widely reported [4,5,6]. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Methods

Results

Conclusion