Allosteric Modulation of G Protein-Coupled Receptors

Allosteric Modulation of G Protein-Coupled Receptors reviews fundamental information on G protein-coupled receptors (GPCRs) and allosteric modulation, presenting original research in the area and collectively providing a comprehensive description of key issues in GPCR allosteric modulation. The book provides background on core concepts of molecular pharmacology while also introducing the most important advances and studies in the area. It also discusses key methodologies. This is an essential book for researchers and advanced students engaged in pharmacology, toxicology and pharmaceutical sciences training and research.

Many of the GPCR-targeted drugs released in the past decade have specifically worked via allosteric mechanisms. Unlike direct orthosteric-acting compounds that occupy a similar receptor site to that of endogenous ligands, allosteric modulators alter GPCR-dependent signaling at a site apart from the endogenous ligand. Recent methodological and analytical advances have greatly improved our ability to understand the signaling mechanisms of GPCRs. We now know that allostery is a common regulatory mechanism for all GPCRs and not – as we once believed – unique to a few receptor subfamilies.

• Introduces background on core concepts of molecular pharmacology, including statistical analyses, non-linear regression, complex models and GPCR-dependent signal transduction as they relate to allosteric modulation
• Discusses critical advances and landmark studies, including discoveries in the area of GPCR allosteric modulation, which are reviewed for their importance in positive and negative regulation, protein-protein interactions, and small molecule drug discovery
• Includes key methodologies used to study allosteric modulation at the in silico, in vitro, and in vivo levels of drug discovery and characterization

• Language: English
• Publisher: Academic Press
• Release date: Feb 5, 2022
• ISBN: 9780128197721

Book preview

Allosteric Modulation of G Protein-Coupled Receptors

Editor

Robert B Laprairie

Assistant Professor and CIHR-GlaxoSmithKline, Chair in Drug Discovery and Development, College of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, SK, Canada

Department of Pharmacology, Faculty of Health Sciences, Dalhousie University, Halifax, NS, Canada

Table of Contents

Cover image

Title page

Copyright

List of contributors

About the editor

Preface

Special thanks

Pedagogical foundation and features

About Allosteric modulation of the G protein-coupled receptors

Section 1. Critical concepts

Chapter 1. Introduction

Introduction

Section I: critical concepts

Section II: important considerations and unique allosteric interactions

Section III: methods for advancing the field

Looking forward

Chapter 2. G protein-coupled receptor (GPCR)-dependent transduction

Introduction

Learning objectives

GPCR allostery

Biased signaling

G protein versus β-arrestin (βarr)

Across and within the G protein pathways

Conclusions

Section 2. Important considerations and unique allosteric interactions

Chapter 3. Computer modeling of allosteric modulators at G protein-coupled receptors

Introduction

Class A GPCRs

Class B GPCRs—secretin family

Class C GPCR's—metabotropic glutamate receptor family

Chapter 4. Ions as GPCR allosteric modulators

Introduction

Ions as allosteric modulators of GPCR activity

GPCR structures and variations

Structural insight into Na+ as a NAM for class-A GPCRs

Inverse agonist activity of BIIL260 to BLT1 that mimics the role of the Na+-centered water cluster

Chapter 5. Protein-protein allosteric effects on cannabinoid receptor heteromer signaling

Introduction

Cannabinoid receptors form heteromers in heterologous expression system

Cannabinoid receptors form heteromers in native tissues

Allosteric control and forms of crosstalk among cannabinoid receptor heteromers

Heteromerization alters signaling among cannabinoid receptors

Therapeutic relevance of cannabinoid receptor heteromers

Future directions

Chapter 6. Allosteric ligands to study medium and long chain free fatty acid GPCRs

Introduction

Allosteric ligands for medium and long chain FFA receptors

Concluding remarks

Section 3. Methods for advancing the field

Chapter 7. Moving from cells to animals: challenges of studying allosteric modulators in vivo

Introduction

Class A G protein-coupled receptor allosteric modulators

Class B G protein-coupled receptor allosteric modulators: GLP-1 glucagonlike peptide receptor 1 allosteric modulators

Class C G protein-coupled receptor allosteric modulators

Conclusions

Chapter 8. Exploring the use of intracellular and extracellular allosteric modulators to understand GPCR signaling

Introduction

Sodium as an endogenous allosteric modulator

Pepducins as allosteric modulators

Nanobodies as allosteric modulators

Nanobodies (intra- and extracellular) in drug discovery

Perspectives

Chapter 9. Allosteric modulation of tethered ligand-activated G protein-coupled receptors

Introduction

PAR allosteric transitions

aGPCR allosteric transitions

PAR allosteric binding sites

aGPCR allosteric binding sites

Regulation of PARs by dimerization

Regulation of aGPCRs by dimerization

Conclusion

Index

Copyright

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ISBN: 978-0-12-819771-4

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List of contributors

Shawn J. Adderley,     Department of Pharmacology, Dalhousie University, Halifax, NS, Canada

Bruce G. Allen

Departments of Medicine, Biochemistry and Molecular Medicine, Pharmacology and Physiology, Université de Montréal, Montréal, QC, Canada

Montreal Heart Institute, Montréal, QC, Canada

Haley Andersen,     College of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, SK, Canada

Amina M. Bagher,     Department of Pharmacology and Toxicology, King Abdulaziz University, Jeddah, Saudi Arabia

Kyla Bourque,     Department of Pharmacology and Therapeutics, McGill University, Montréal, QC, Canada

Asher L. Brandt,     College of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, SK, Canada

David Chatenet,     Institut National de la Recherche Scientifique, Centre Armand-Frappier Santé Biotechnologie, Ville de Laval, QC, Canada

Juliana C.C. Dallagnol,     Department of Pharmacology and Therapeutics, McGill University, Montréal, QC, Canada

Eileen M. Denovan-Wright,     Department of Pharmacology, Dalhousie University, Halifax, NS, Canada

Tetsuya Hori

RIKEN Cluster for Science, Technology and Innovation Hub, Yokohama, Japan

Laboratory for Chemical Biology, RIKEN Center for Biosystems Dynamics Research, Yokohama, Japan

Terence E. Hébert,     Department of Pharmacology and Therapeutics, McGill University, Montréal, QC, Canada

Brian D. Hudson,     The Centre for Translational Pharmacology, Institute for Molecular Cell and Systems Biology, University of Glasgow, Glasgow, United Kingdom

Robert B. Laprairie

College of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, SK, Canada

Department of Pharmacology, Faculty of Health Sciences, Dalhousie University, Halifax, NS, Canada

Victor Michael Mirka,     Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada

Hassan Nassour,     Institut National de la Recherche Scientifique, Centre Armand-Frappier Santé Biotechnologie, Ville de Laval, QC, Canada

Rithwik Ramachandran,     Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada

Shigeyuki Yokoyama,     RIKEN Cluster for Science, Technology and Innovation Hub, Yokohama, Japan

Alexander P. Young,     Department of Pharmacology, Dalhousie University, Halifax, NS, Canada

About the editor

Dr. Robert Laprairie is the GlaxoSmithKline-Canadian Institutes of Health Research (GSK-CIHR) chair in Drug Discovery and Development in the College of Pharmacy and Nutrition at the University of Saskatchewan. Robert holds a BSc in biochemistry (University of Saskatchewan, 2010), MSc in pharmacology and neuroscience (Dalhousie University, 2012), and PhD in pharmacology (Dalhousie University, 2016). He completed a postdoctoral fellowship at The Scripps Research Institute. He is a member of the Drug Discovery and Development Research Group (DDDRG) and the Cannabinoid Research Initiative of Saskatchewan (CRIS). He is the President and Director of Education for the Canadian Consortium for the Investigation of Cannabinoids (CCIC). Robert and his lab have always been interested in G protein-coupled receptor (GPCR) pharmacology with a particular focus on the cannabinoid receptors. To date, Robert and his colleagues have published 50 studies spanning from in silico drug characterization to clinical evaluation of the cannabinoids.

Preface

Allosteric modulation of the G protein-coupled receptors is designed as a broad overview of the critical and emerging concepts in G protein-coupled receptor (GPCR) allosteric interaction and is geared toward young—or young in mind—researchers entering this field of pharmacology. The textbook follows a natural progression from chemical and in silico evaluation through special challenge cases and caveat to preclinical evaluation in vivo.

Special thanks

As the editor of this text, I am grateful to the work of the chapter authors and their important contributions to this rapidly growing field. I wish to thank all those who provided resources, time, and feedback, without which production of this textbook would not have been possible. The editor also acknowledges that the authors of this book worked through the COVID-19 pandemic to bring together this document. During a time of global challenges, personal, and professional difficulties, the editor deeply appreciates the long-term efforts undertaken by all authors to see this work through to completion.

Pedagogical foundation and features

Allosteric modulation of the G protein-coupled receptors is designed to enhance scientific knowledge of the emerging field of GPCR allosteric design, which is increasingly dominant within molecular pharmacology. In this textbook, emergent themes and concepts are repeated and emphasized to connect recent findings in the field back to fundamental pharmacological principles.

• Allosterism as a broad and inclusive concept. Often, allosteric interactions are viewed through the narrow lens of small molecules. Here, we will explore allostery as being any and all interactions between a GPCR and another molecule (ion, protein, lipid, etc.) outside of the traditional described orthosteric or main ligand-binding domain.

• Fundamental pharmacology concepts including agonism, antagonism, potency, efficacy, affinity, co-operativity, and ligand bias are all influenced by allosteric interactions. Thus, allosteric modulation will routinely be described as an added layer of complexity on top of these existing concepts.

• Crystallography and 3D representation: Molecular pharmacology as a discipline is increasingly reliant upon crystallography, cryo-EM, and molecular modeling to explore novel compound structure–activity relationships. Therefore, GPCRs are frequently displayed as 3D models with originally referencing given to real world data and public databases so that readers can explore these GPCRs models deeper.

• Diseases and disorders represent the impetus for many of these novel allosteric modulators being developed. Therefore, disease pathophysiology is often described to contextualize and rationalize the development of novel allosteric modulators.

• Real world connections tie pharmacological concepts to emerging issues using first-hand data and experiences to describe issues, caveats, limitations, and important advancements in the field.

About Allosteric modulation of the G protein-coupled receptors

Allosteric modulation of the G protein-coupled receptors is designed for researchers with an existing background in basic principles of molecular biology and pharmacology at the senior undergraduate or graduate level, at a minimum. Chapter authors have heavily cited original and landmark studies in our field to guide the reader should they wish to go deeper in their knowledge of a specific area.

Writing style, figure formatting, and topics covered were made with the guidance of all contributing authors. We worked to assemble a meaningful breadth and depth of knowledge to familiarize readers with critical and emerging concepts in this increasingly important subgenre of pharmacology.

Section 1

Critical concepts

Outline

Chapter 1. Introduction

Chapter 2. G protein-coupled receptor (GPCR)-dependent transduction

Chapter 1: Introduction

Robert B. Laprairie ¹ , ²       ¹ College of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, SK, Canada      ² Department of Pharmacology, Faculty of Health Sciences, Dalhousie University, Halifax, NS, Canada

Abstract

G protein-coupled receptors (GPCRs) are the most-targeted class of protein for novel and approved drugs. Nearly 50% of all drugs presently sold on the global market target a GPCR and GPCR-targeted therapeutics represent approximately 34% of all drugs that have been approved by the Food and Drug Administration. There are thought to be 108 members of the GPCR family with a wide variety of endogenous ligands, signaling activities, and patterns of tissue expression; yet all GPCRs share several common structural features including seven transmembrane α-helices, an extracellular N-terminus, an intracellular C-terminus, and the ability to couple with and signal via guanine nucleotide binding proteins (G proteins). Historically, GPCRs were thought to propagate their signal from the extracellular environment into the cell through the binding of a ligand agonist to the orthosteric (i.e., primary) receptor site and the consequent conformational change of that receptor which allowed for G protein activation. More recently, it has become apparent that the activity of GPCRs is fine-tuned and controlled by a wide array of signaling partners that bind allosteric (i.e.,‘other) receptor sites. Novel and precise regulation of GPCRs stemming from allosteric sites may lead to the development of improved drugs targeting a protein family with an already successful history of drug development. The purpose of this chapter is to summarize some leading areas of research in allosteric modulation of GPCRs where knowledge gaps have, or are, actively being addressed. Each of these areas will then be elaborated on in their own subsequent chapters. The research described herein focuses on preclinical evaluation of allostery for GPCRs with an emphasis on core and emerging concepts in pharmacology, biochemistry, and medicinal chemistry.

Keywords

Allosteric modulator; Behavioral pharmacology; G protein-coupled receptor; Ligand bias; Molecular pharmacology; Probe-dependence; Signal transduction

Acknowledgments

Introduction

Section I: critical concepts

Section II: important considerations and unique allosteric interactions

Section III: methods for advancing the field

Looking forward

References

Introduction

G protein-coupled receptors (GPCRs) are a large family of over 108 members of signal transduction proteins that reside in the plasma membrane [1]. With few exceptions, GPCRs are composed of an extracellular N-terminus, seven transmembrane α-helices, and an intracellular C-terminus [1,2]. Six classes of GPCRs have been described on the basis of their sequence homology and/or functional similarity to key members of each class: Class A (rhodopsin receptor family); Class B (secretin receptor family); Class C (metabotropic glutamate receptor family); Class D (fungal pheromone receptor family); Class E (cAMP receptor family); and Class F (frizzled/smoothened receptor family) [3–5]. Debate about this classification system is ongoing [6], but within this classification system Class A is by far the group with the most members and the best-studied of the GPCR classes [3–6]. According to the classical model of GPCR signal transduction, the binding of an endogenous or exogenous agonist ligand to the primary (i.e., orthosteric) site of the receptor produces a conformational change in that GPCR to adopt a conformation that is permissive to the binding of the G protein to its intracellular surface [6,7] (Fig. 1.1A). Upon G protein binding to the GPCR, the G protein α subunit is able to undergo guanosine diphosphate (GDP) to guanosine triphosphate (GTP) exchange and activation; which can then lead to a myriad of intracellular signaling cascades including activation of adenylate cyclase (GαS), inhibition of adenylate cyclase (Gαi/o), activation of phospholipase C-β (Gαq/11), and others [6,7]. GPCR-dependent signaling also occurs via the β and γ subunits of the G protein and G protein-independent signaling through proteins such as β-arrestins [6–8] (Fig. 1.1B). This classical model of GPCR activation occurring as the result of agonist ligand binding to an orthosteric site—or inhibition of activation through orthosteric antagonism—forms the foundation for much of molecular pharmacology; with commonly used equations such as the Hill Equation (Eq. 1.1) and operational model [9–11] (Eq. 1.2) built upon orthosteric ligand concentration, effect magnitude, and the assumption of orthosteric ligand and ligand–receptor complex equilibrium. Within the past 20 years, however, there has been a growing acknowledgment that GPCR's signal communication is regulated by numerous interacting partners beyond their orthosteric ligands [12–14]. These additional partners include other small molecules and peptides, receptors and GPCRs, ions, and the lipid content of the plasma membrane; all of which interact with GPCRs at unique sites apart from the orthosteric site of binding [2,14]. These other sites are now collectively referred to as allosteric sites and the entities that bind to these separate sites are allosteric modulators [2,14].

Figure 1.1 GPCR signal transduction. (A) The binding of an orthosteric agonist, such as the receptor's endogenous ligand, to the GPCRs orthosteric site allows for G protein coupling. (B) GPCRs may couple to various types of G protein to evoke different intracellular effects. (C) Allosteric modulation of GPCRs may occur by small molecules, ion, proteins, and lipids, among others.

(1.1)

(1.2)

Since 2000, more than 1000 research articles have been published on GPCR allostery, with publications in this area steadily rising each consecutive year. Today, GPCRs are considered as being fundamentally allosteric proteins, meaning that no function of a GPCR occurs independent of allosteric modulation by other interacting partners [15]. Obviously, this makes the interpretation of pharmacological data for GPCRs far more complex than previously understood, and made modeling of pharmacological effects more challenging, such as with the operational model of allosterism (Fig. 1.1C, Eq. 1.3) [15,16]. However, it also reveals the possibility to better understand the true biological workings of these molecular microprocessors. In this textbook, we will explore our current understanding of GPCR allosteric modulation from a comprehensive perspective, which includes all interacting partners of GPCRs and we will discuss current techniques, approaches, and challenges to understanding GPCR allostery.

(1.3)

Adapted from Ref. [15].

Section I: critical concepts

This book presents a collection of chapters addressing important considerations of allosteric modulation and GPCR pharmacology. These chapters have been organized to begin with an overview of molecular GPCR signal transduction via both orthosteric ligands and allosteric modulators, including considerations in mapping the structure-activity relationships of allosteric modulators to their various sites (Chapter 2). Dr. Andersen provides an overview of allosteric modulation and signal transduction while exploring key examples for the past 20 years of work.

Section II: important considerations and unique allosteric interactions

Following from data presented in Part I of this text, Part II of this book explores the concepts of allosteric interaction with a wider lens encompassing all possible molecule-GPCR interactions that exist under the umbrella of allostery. Dr. Yokohama and his group (Chapter 3) describe the activity of ions as allosteric modulators of GPCRs and use real-world data and analyses to explore the importance of ions on GPCR signal transduction. Dr. Hudson further explores allosteric modulation of GPCRs by describing lipids and fatty acids and their important roles in regulating receptor localization and signal transduction (Chapter 4). Next, we will explore