Molecular mapping and functional validation of GLP-1R cholesterol binding sites in pancreatic beta cells
File(s)
Reviewed Preprint
Author(s)
Type
Journal Article
Abstract
G protein-coupled receptors (GPCRs) are integral membrane proteins which closely interact
with their plasma membrane lipid microenvironment. Cholesterol is a plasma membrane
enriched lipid with pivotal roles in the control of membrane fluidity and maintenance of
membrane microarchitecture, directly impacting on GPCR stability, dynamics and function.
Cholesterol extraction from pancreatic beta cells has previously been shown to disrupt the
internalisation, clustering and cAMP responses of the glucagon-like peptide-1 receptor (GLP 1R), a class B1 GPCR with key roles in the control of blood glucose levels via the potentiation
of insulin secretion in beta cells and weight reduction via the modulation of brain appetite
control centres. Here, we unveil the detrimental effect of a high cholesterol diet on GLP-1R dependent glucoregulation in vivo, and the improvement in GLP-1R function that a reduction
in cholesterol synthesis using simvastatin exerts in pancreatic islets. We next identify and map
sites of cholesterol high occupancy and residence time on active versus inactive GLP-1Rs
using coarse-grained molecular dynamics (cgMD) simulations, followed by a screen of key
residues selected from these sites and detailed analyses of the effects of mutating one of
these residues, Val229, to alanine on GLP-1R interactions with cholesterol, plasma membrane
behaviours, clustering, trafficking and signalling in pancreatic beta cells and primary islets,
unveiling an improved insulin secretion profile for the V229A mutant receptor. This study 1)
highlights the role of cholesterol in regulating GLP-1R responses in vivo; 2) provides a detailed
map of GLP-1R - cholesterol binding sites in model membranes; 3) validates their functional
relevance in beta cells; and 4) highlights their potential as locations for the rational design of
novel allosteric modulators with the capacity to fine-tune GLP-1R responses.
with their plasma membrane lipid microenvironment. Cholesterol is a plasma membrane
enriched lipid with pivotal roles in the control of membrane fluidity and maintenance of
membrane microarchitecture, directly impacting on GPCR stability, dynamics and function.
Cholesterol extraction from pancreatic beta cells has previously been shown to disrupt the
internalisation, clustering and cAMP responses of the glucagon-like peptide-1 receptor (GLP 1R), a class B1 GPCR with key roles in the control of blood glucose levels via the potentiation
of insulin secretion in beta cells and weight reduction via the modulation of brain appetite
control centres. Here, we unveil the detrimental effect of a high cholesterol diet on GLP-1R dependent glucoregulation in vivo, and the improvement in GLP-1R function that a reduction
in cholesterol synthesis using simvastatin exerts in pancreatic islets. We next identify and map
sites of cholesterol high occupancy and residence time on active versus inactive GLP-1Rs
using coarse-grained molecular dynamics (cgMD) simulations, followed by a screen of key
residues selected from these sites and detailed analyses of the effects of mutating one of
these residues, Val229, to alanine on GLP-1R interactions with cholesterol, plasma membrane
behaviours, clustering, trafficking and signalling in pancreatic beta cells and primary islets,
unveiling an improved insulin secretion profile for the V229A mutant receptor. This study 1)
highlights the role of cholesterol in regulating GLP-1R responses in vivo; 2) provides a detailed
map of GLP-1R - cholesterol binding sites in model membranes; 3) validates their functional
relevance in beta cells; and 4) highlights their potential as locations for the rational design of
novel allosteric modulators with the capacity to fine-tune GLP-1R responses.
Date Issued
2024-09-17
Date Acceptance
2024-07-19
Citation
eLife, 2024
ISSN
2050-084X
Publisher
eLife Sciences Publications Ltd
Journal / Book Title
eLife
Copyright Statement
© 2024, Oqua et al.
This article is distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use and redistribution provided that the original author and source are credited.
This article is distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use and redistribution provided that the original author and source are credited.
License URL
Identifier
https://elifesciences.org/reviewed-preprints/101011
Publication Status
Published
Date Publish Online
2024-09-17