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Garelja M, Au M, Brimble MA, Gingell JJ, Hendrikse ER, Lovell A, Prodan N, Sexton PM, Siow A, Walker CS, Watkins HA, Williams GM, Wootten D, Yang SH, Harris PWR, Hay DL. Molecular Mechanisms of Class B GPCR Activation: Insights from Adrenomedullin Receptors. ACS Pharmacol Transl Sci 2020; 3:246-262. [PMID: 32296766 PMCID: PMC7155197 DOI: 10.1021/acsptsci.9b00083] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Indexed: 02/07/2023]
Abstract
Adrenomedullin (AM) is a 52 amino acid peptide that plays a regulatory role in the vasculature. Receptors for AM comprise the class B G protein-coupled receptor, the calcitonin-like receptor (CLR), in complex with one of three receptor activity-modifying proteins (RAMPs). The C-terminus of AM is involved in binding to the extracellular domain of the receptor, while the N-terminus is proposed to interact with the juxtamembranous portion of the receptor to activate signaling. There is currently limited information on the molecular determinants involved in AM signaling, thus we set out to define the importance of the AM N-terminus through five signaling pathways (cAMP production, ERK phosphorylation, CREB phosphorylation, Akt phosphorylation, and IP1 production). We characterized the three CLR:RAMP complexes through the five pathways, finding that each had a distinct repertoire of intracellular signaling pathways that it is able to regulate. We then performed an alanine scan of AM from residues 15-31 and found that most residues could be substituted with only small effects on signaling, and that most substitutions affected signaling through all receptors and pathways in a similar manner. We identify F18, T20, L26, and I30 as being critical for AM function, while also identifying an analogue (AM15-52 G19A) which has unique signaling properties relative to the unmodified AM. We interpret our findings in the context of new structural information, highlighting the complementary nature of structural biology and functional assays.
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Affiliation(s)
- Michael
L. Garelja
- School
of Biological Sciences, University of Auckland, Auckland, 1010, New Zealand
| | - Maggie Au
- School
of Biological Sciences, University of Auckland, Auckland, 1010, New Zealand
- Maurice
Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland, 1010, New Zealand
| | - Margaret A. Brimble
- School
of Biological Sciences, University of Auckland, Auckland, 1010, New Zealand
- Maurice
Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland, 1010, New Zealand
- School
of Chemical Sciences, University of Auckland, Auckland, 1010, New Zealand
| | - Joseph J. Gingell
- School
of Biological Sciences, University of Auckland, Auckland, 1010, New Zealand
- Maurice
Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland, 1010, New Zealand
| | - Erica R. Hendrikse
- School
of Biological Sciences, University of Auckland, Auckland, 1010, New Zealand
| | - Annie Lovell
- School
of Biological Sciences, University of Auckland, Auckland, 1010, New Zealand
| | - Nicole Prodan
- School
of Biological Sciences, University of Auckland, Auckland, 1010, New Zealand
| | - Patrick M. Sexton
- Drug
Discovery Biology and Department of Pharmacology, Monash Institute
of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Andrew Siow
- School
of Biological Sciences, University of Auckland, Auckland, 1010, New Zealand
- School
of Chemical Sciences, University of Auckland, Auckland, 1010, New Zealand
| | - Christopher S. Walker
- School
of Biological Sciences, University of Auckland, Auckland, 1010, New Zealand
- Maurice
Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland, 1010, New Zealand
| | - Harriet A. Watkins
- School
of Biological Sciences, University of Auckland, Auckland, 1010, New Zealand
- Maurice
Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland, 1010, New Zealand
| | - Geoffrey M. Williams
- Maurice
Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland, 1010, New Zealand
- School
of Chemical Sciences, University of Auckland, Auckland, 1010, New Zealand
| | - Denise Wootten
- Drug
Discovery Biology and Department of Pharmacology, Monash Institute
of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Sung H. Yang
- School
of Biological Sciences, University of Auckland, Auckland, 1010, New Zealand
- Maurice
Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland, 1010, New Zealand
| | - Paul W. R. Harris
- School
of Biological Sciences, University of Auckland, Auckland, 1010, New Zealand
- Maurice
Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland, 1010, New Zealand
- School
of Chemical Sciences, University of Auckland, Auckland, 1010, New Zealand
| | - Debbie L. Hay
- School
of Biological Sciences, University of Auckland, Auckland, 1010, New Zealand
- Maurice
Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland, 1010, New Zealand
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Musa H, Hendrikse ER, Brimble MA, Garelja ML, Watkins HA, Harris PWR, Hay DL. Pharmacological Characterization and Investigation of N-Terminal Loop Amino Acids of Adrenomedullin 2 That Are Important for Receptor Activation. Biochemistry 2019; 58:3468-3474. [PMID: 31328503 DOI: 10.1021/acs.biochem.9b00571] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Adrenomedullin 2 (AM2) is a peptide hormone with potent effects in the cardiovascular system. The N-terminal disulfide loop of AM2 is thought to be important for interacting with its receptors to initiate a signaling response. However, the relative contribution of each amino acid within this region is currently unknown. Thus, the region was investigated using an alanine scanning approach. Two AM2 peptides (AM2-47 and AM2-40) were directly compared at the CGRP, AM1, and AM2 receptors in transfected Cos7 cells and found to have equivalent activity. Analogues of AM2-40 were then synthesized, substituting each individual amino acid within the disulfide loop with alanine. The ability of these analogues to stimulate a cAMP response was evaluated at the CGRP, AM1, and AM2 receptors. AM2-40 L12A and T14A were less able to elicit cAMP responses through all tested receptors. In contrast, AM2-40 G13A was slightly more potent than the unmodified peptide at all tested receptors. Thus, it appears that residues within the disulfide loop region play differential roles in the ability of AM2 to stimulate cAMP production. The data provide the first structure-function investigation of AM2 agonism.
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Affiliation(s)
- Hala Musa
- School of Biological Sciences , The University of Auckland , 3A Symonds Street , Auckland 1010 , New Zealand
| | - Erica R Hendrikse
- School of Biological Sciences , The University of Auckland , 3A Symonds Street , Auckland 1010 , New Zealand
| | - Margaret A Brimble
- School of Biological Sciences , The University of Auckland , 3A Symonds Street , Auckland 1010 , New Zealand.,Maurice Wilkins Centre for Molecular Biodiscovery , The University of Auckland , 3A Symonds Street , Auckland 1010 , New Zealand.,School of Chemical Sciences , The University of Auckland , 23 Symonds Street , Auckland 1010 , New Zealand
| | - Michael L Garelja
- School of Biological Sciences , The University of Auckland , 3A Symonds Street , Auckland 1010 , New Zealand
| | - Harriet A Watkins
- School of Biological Sciences , The University of Auckland , 3A Symonds Street , Auckland 1010 , New Zealand
| | - Paul W R Harris
- School of Biological Sciences , The University of Auckland , 3A Symonds Street , Auckland 1010 , New Zealand.,Maurice Wilkins Centre for Molecular Biodiscovery , The University of Auckland , 3A Symonds Street , Auckland 1010 , New Zealand.,School of Chemical Sciences , The University of Auckland , 23 Symonds Street , Auckland 1010 , New Zealand
| | - Debbie L Hay
- School of Biological Sciences , The University of Auckland , 3A Symonds Street , Auckland 1010 , New Zealand.,Maurice Wilkins Centre for Molecular Biodiscovery , The University of Auckland , 3A Symonds Street , Auckland 1010 , New Zealand
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3
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Garelja ML, Walker CA, Siow A, Yang SH, Harris PWR, Brimble MA, Watkins HA, Gingell JJ, Hay DL. Receptor Activity Modifying Proteins Have Limited Effects on the Class B G Protein-Coupled Receptor Calcitonin Receptor-Like Receptor Stalk. Biochemistry 2018; 57:1410-1422. [PMID: 29388762 DOI: 10.1021/acs.biochem.7b01180] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The calcitonin receptor-like receptor (CLR) is a class B G protein-coupled receptor (GPCR) that forms the basis of three pharmacologically distinct receptors, the calcitonin gene-related peptide (CGRP) receptor, and two adrenomedullin (AM) receptors. These three receptors are created by CLR interacting with three receptor activity-modifying proteins (RAMPs). Class B GPCRs have an N-terminal extracellular domain (ECD) and transmembrane bundle that are both important for binding endogenous ligands. These two domains are joined together by a stretch of amino acids that is referred to as the "stalk". Studies of other class B GPCRs suggest that the stalk may act as hinge, allowing the ECD to adopt multiple conformations. It is unclear what the role of the stalk is within CLR and whether RAMPs can influence its function. Therefore, this study investigated the role of this region using an alanine scan. Effects of mutations were measured with all three RAMPs through cell surface expression, cAMP production and, in select cases, radioligand binding and total cell expression assays. Most mutants did not affect expression or cAMP signaling. CLR C127A, N140A, F142A, and L144A impaired cell surface expression with all three RAMPs. T125A decreased the potency of all peptides at all receptors. N128A, V135A, and L139A showed ligand-dependent effects. While the stalk appears to play a role in CLR function, the effect of RAMPs on this region seems limited, in contrast to their effects on the structure of CLR in other receptor regions.
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Affiliation(s)
- Michael L Garelja
- School of Biological Sciences, University of Auckland , 3A Symonds Street Auckland 1010, New Zealand
| | - Christina A Walker
- School of Biological Sciences, University of Auckland , 3A Symonds Street Auckland 1010, New Zealand
| | - Andrew Siow
- School of Biological Sciences, University of Auckland , 3A Symonds Street Auckland 1010, New Zealand.,Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland , 3A Symonds Street, Auckland 1010, New Zealand
| | - Sung H Yang
- School of Biological Sciences, University of Auckland , 3A Symonds Street Auckland 1010, New Zealand.,Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland , 3A Symonds Street, Auckland 1010, New Zealand
| | - Paul W R Harris
- School of Biological Sciences, University of Auckland , 3A Symonds Street Auckland 1010, New Zealand.,Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland , 3A Symonds Street, Auckland 1010, New Zealand
| | - Margaret A Brimble
- School of Biological Sciences, University of Auckland , 3A Symonds Street Auckland 1010, New Zealand.,Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland , 3A Symonds Street, Auckland 1010, New Zealand.,School of Chemical Sciences, The University of Auckland , 23 Symonds Street, Auckland 1010, New Zealand
| | - Harriet A Watkins
- School of Biological Sciences, University of Auckland , 3A Symonds Street Auckland 1010, New Zealand
| | - Joseph J Gingell
- School of Biological Sciences, University of Auckland , 3A Symonds Street Auckland 1010, New Zealand
| | - Debbie L Hay
- School of Biological Sciences, University of Auckland , 3A Symonds Street Auckland 1010, New Zealand.,Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland , 3A Symonds Street, Auckland 1010, New Zealand
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Weston C, Winfield I, Harris M, Hodgson R, Shah A, Dowell SJ, Mobarec JC, Woodcock DA, Reynolds CA, Poyner DR, Watkins HA, Ladds G. Receptor activity-modifying protein-directed G protein signaling specificity for the calcitonin gene-related peptide family of receptors. J Biol Chem 2016; 291:25763. [PMID: 27913664 PMCID: PMC5207273 DOI: 10.1074/jbc.a116.751362] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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5
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Weston C, Winfield I, Harris M, Hodgson R, Shah A, Dowell SJ, Mobarec JC, Woodlock DA, Reynolds CA, Poyner DR, Watkins HA, Ladds G. Receptor Activity-modifying Protein-directed G Protein Signaling Specificity for the Calcitonin Gene-related Peptide Family of Receptors. J Biol Chem 2016; 291:21925-21944. [PMID: 27566546 PMCID: PMC5063977 DOI: 10.1074/jbc.m116.751362] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Indexed: 11/08/2022] Open
Abstract
The calcitonin gene-related peptide (CGRP) family of G protein-coupled receptors (GPCRs) is formed through the association of the calcitonin receptor-like receptor (CLR) and one of three receptor activity-modifying proteins (RAMPs). Binding of one of the three peptide ligands, CGRP, adrenomedullin (AM), and intermedin/adrenomedullin 2 (AM2), is well known to result in a Gαs-mediated increase in cAMP. Here we used modified yeast strains that couple receptor activation to cell growth, via chimeric yeast/Gα subunits, and HEK-293 cells to characterize the effect of different RAMP and ligand combinations on this pathway. We not only demonstrate functional couplings to both Gαs and Gαq but also identify a Gαi component to CLR signaling in both yeast and HEK-293 cells, which is absent in HEK-293S cells. We show that the CGRP family of receptors displays both ligand- and RAMP-dependent signaling bias among the Gαs, Gαi, and Gαq/11 pathways. The results are discussed in the context of RAMP interactions probed through molecular modeling and molecular dynamics simulations of the RAMP-GPCR-G protein complexes. This study further highlights the importance of RAMPs to CLR pharmacology and to bias in general, as well as identifying the importance of choosing an appropriate model system for the study of GPCR pharmacology.
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Affiliation(s)
- Cathryn Weston
- From the Division of Biomedical Cell Biology, Warwick Medical School, University of Warwick, Coventry, CV4 7AL, United Kingdom
| | - Ian Winfield
- From the Division of Biomedical Cell Biology, Warwick Medical School, University of Warwick, Coventry, CV4 7AL, United Kingdom, the Department of Pharmacology, University of Cambridge, Cambridge, CB2 1PD, United Kingdom
| | - Matthew Harris
- the Department of Pharmacology, University of Cambridge, Cambridge, CB2 1PD, United Kingdom
| | - Rose Hodgson
- From the Division of Biomedical Cell Biology, Warwick Medical School, University of Warwick, Coventry, CV4 7AL, United Kingdom
| | - Archna Shah
- From the Division of Biomedical Cell Biology, Warwick Medical School, University of Warwick, Coventry, CV4 7AL, United Kingdom
| | - Simon J Dowell
- the Department of Platform Technology and Science, GlaxoSmithkline, Hertfordshire, SG1 2NY, United Kingdom
| | - Juan Carlos Mobarec
- the School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, Essex, CO4 3SQ, United Kingdom
| | - David A Woodlock
- the School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, Essex, CO4 3SQ, United Kingdom
| | - Christopher A Reynolds
- the School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, Essex, CO4 3SQ, United Kingdom
| | - David R Poyner
- the School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham, B4 7ET, United Kingdom, and
| | - Harriet A Watkins
- the School of Biological Sciences and Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland 1010, New Zealand
| | - Graham Ladds
- the Department of Pharmacology, University of Cambridge, Cambridge, CB2 1PD, United Kingdom,
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Watkins HA, Chakravarthy M, Abhayawardana RS, Gingell JJ, Garelja M, Pardamwar M, McElhinney JMWR, Lathbridge A, Constantine A, Harris PWR, Yuen TY, Brimble MA, Barwell J, Poyner DR, Woolley MJ, Conner AC, Pioszak AA, Reynolds CA, Hay DL. Receptor Activity-modifying Proteins 2 and 3 Generate Adrenomedullin Receptor Subtypes with Distinct Molecular Properties. J Biol Chem 2016; 291:11657-75. [PMID: 27013657 PMCID: PMC4882435 DOI: 10.1074/jbc.m115.688218] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Revised: 03/20/2016] [Indexed: 01/28/2023] Open
Abstract
Adrenomedullin (AM) is a peptide hormone with numerous effects in the vascular systems. AM signals through the AM1 and AM2 receptors formed by the obligate heterodimerization of a G protein-coupled receptor, the calcitonin receptor-like receptor (CLR), and receptor activity-modifying proteins 2 and 3 (RAMP2 and RAMP3), respectively. These different CLR-RAMP interactions yield discrete receptor pharmacology and physiological effects. The effective design of therapeutics that target the individual AM receptors is dependent on understanding the molecular details of the effects of RAMPs on CLR. To understand the role of RAMP2 and -3 on the activation and conformation of the CLR subunit of AM receptors, we mutated 68 individual amino acids in the juxtamembrane region of CLR, a key region for activation of AM receptors, and determined the effects on cAMP signaling. Sixteen CLR mutations had differential effects between the AM1 and AM2 receptors. Accompanying this, independent molecular modeling of the full-length AM-bound AM1 and AM2 receptors predicted differences in the binding pocket and differences in the electrostatic potential of the two AM receptors. Druggability analysis indicated unique features that could be used to develop selective small molecule ligands for each receptor. The interaction of RAMP2 or RAMP3 with CLR induces conformational variation in the juxtamembrane region, yielding distinct binding pockets, probably via an allosteric mechanism. These subtype-specific differences have implications for the design of therapeutics aimed at specific AM receptors and for understanding the mechanisms by which accessory proteins affect G protein-coupled receptor function.
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Affiliation(s)
- Harriet A Watkins
- From the School of Biological Sciences, the Maurice Wilkins Centre for Molecular Biodiscovery, and
| | | | | | - Joseph J Gingell
- From the School of Biological Sciences, the Maurice Wilkins Centre for Molecular Biodiscovery, and
| | | | - Meenakshi Pardamwar
- the School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, United Kingdom
| | - James M W R McElhinney
- the School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, United Kingdom
| | - Alex Lathbridge
- the School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, United Kingdom
| | - Arran Constantine
- the School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, United Kingdom
| | - Paul W R Harris
- the Maurice Wilkins Centre for Molecular Biodiscovery, and the School of Chemical Sciences, University of Auckland, Auckland 1010, New Zealand
| | - Tsz-Ying Yuen
- the Maurice Wilkins Centre for Molecular Biodiscovery, and the School of Chemical Sciences, University of Auckland, Auckland 1010, New Zealand
| | - Margaret A Brimble
- the Maurice Wilkins Centre for Molecular Biodiscovery, and the School of Chemical Sciences, University of Auckland, Auckland 1010, New Zealand
| | - James Barwell
- the School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, United Kingdom
| | - David R Poyner
- the School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham B4 7ET, United Kingdom
| | - Michael J Woolley
- the School of Clinical and Experimental Medicine, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - Alex C Conner
- the School of Clinical and Experimental Medicine, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - Augen A Pioszak
- the Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Christopher A Reynolds
- the School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, United Kingdom,
| | - Debbie L Hay
- From the School of Biological Sciences, the Maurice Wilkins Centre for Molecular Biodiscovery, and
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7
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J Gingell J, Simms J, Barwell J, Poyner DR, Watkins HA, Pioszak AA, Sexton PM, Hay DL. An allosteric role for receptor activity-modifying proteins in defining GPCR pharmacology. Cell Discov 2016; 2:16012. [PMID: 27462459 PMCID: PMC4869360 DOI: 10.1038/celldisc.2016.12] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 02/24/2016] [Indexed: 12/15/2022] Open
Abstract
G protein-coupled receptors are allosteric proteins that control transmission of external signals to regulate cellular response. Although agonist binding promotes canonical G protein signalling transmitted through conformational changes, G protein-coupled receptors also interact with other proteins. These include other G protein-coupled receptors, other receptors and channels, regulatory proteins and receptor-modifying proteins, notably receptor activity-modifying proteins (RAMPs). RAMPs have at least 11 G protein-coupled receptor partners, including many class B G protein-coupled receptors. Prototypic is the calcitonin receptor, with altered ligand specificity when co-expressed with RAMPs. To gain molecular insight into the consequences of this protein–protein interaction, we combined molecular modelling with mutagenesis of the calcitonin receptor extracellular domain, assessed in ligand binding and functional assays. Although some calcitonin receptor residues are universally important for peptide interactions (calcitonin, amylin and calcitonin gene-related peptide) in calcitonin receptor alone or with receptor activity-modifying protein, others have RAMP-dependent effects, whereby mutations decreased amylin/calcitonin gene-related peptide potency substantially only when RAMP was present. Remarkably, the key residues were completely conserved between calcitonin receptor and AMY receptors, and between subtypes of AMY receptor that have different ligand preferences. Mutations at the interface between calcitonin receptor and RAMP affected ligand pharmacology in a RAMP-dependent manner, suggesting that RAMP may allosterically influence the calcitonin receptor conformation. Supporting this, molecular dynamics simulations suggested that the calcitonin receptor extracellular N-terminal domain is more flexible in the presence of receptor activity-modifying protein 1. Thus, RAMPs may act in an allosteric manner to generate a spectrum of unique calcitonin receptor conformational states, explaining the pharmacological preferences of calcitonin receptor-RAMP complexes. This provides novel insight into our understanding of G protein-coupled receptor-protein interaction that is likely broadly applicable for this receptor class.
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Affiliation(s)
- Joseph J Gingell
- School of Biological Sciences, University of Auckland, Auckland, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland, New Zealand
| | - John Simms
- School of Life and Health Sciences, Aston University , Birmingham, UK
| | - James Barwell
- School of Life and Health Sciences, Aston University , Birmingham, UK
| | - David R Poyner
- School of Life and Health Sciences, Aston University , Birmingham, UK
| | - Harriet A Watkins
- School of Biological Sciences, University of Auckland, Auckland, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland, New Zealand
| | - Augen A Pioszak
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center , Oklahoma City, OK, USA
| | - Patrick M Sexton
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University , Parkville, VIC, Australia
| | - Debbie L Hay
- School of Biological Sciences, University of Auckland, Auckland, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland, New Zealand
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Watkins HA, Walker CS, Ly KN, Bailey RJ, Barwell J, Poyner DR, Hay DL. Receptor activity-modifying protein-dependent effects of mutations in the calcitonin receptor-like receptor: implications for adrenomedullin and calcitonin gene-related peptide pharmacology. Br J Pharmacol 2014; 171:772-88. [PMID: 24199627 PMCID: PMC3969088 DOI: 10.1111/bph.12508] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Revised: 10/22/2013] [Accepted: 10/30/2013] [Indexed: 01/22/2023] Open
Abstract
Background and Purpose Receptor activity-modifying proteins (RAMPs) define the pharmacology of the calcitonin receptor-like receptor (CLR). The interactions of the different RAMPs with this class B GPCR yield high-affinity calcitonin gene-related peptide (CGRP) or adrenomedullin (AM) receptors. However, the mechanism for this is unclear. Experimental Approach Guided by receptor models, we mutated residues in the N-terminal helix of CLR, RAMP2 and RAMP3 hypothesized to be involved in peptide interactions. These were assayed for cAMP production with AM, AM2 and CGRP together with their cell surface expression. Binding studies were also conducted for selected mutants. Key Results An important domain for peptide interactions on CLR from I32 to I52 was defined. Although I41 was universally important for binding and receptor function, the role of other residues depended on both ligand and RAMP. Peptide binding to CLR/RAMP3 involved a more restricted range of residues than that to CLR/RAMP1 or CLR/RAMP2. E101 of RAMP2 had a major role in AM interactions, and F111/W84 of RAMP2/3 was important with each peptide. Conclusions and Implications RAMP-dependent effects of CLR mutations suggest that the different RAMPs control accessibility of peptides to binding residues situated on the CLR N-terminus. RAMP3 appears to alter the role of specific residues at the CLR-RAMP interface compared with RAMP1 and RAMP2.
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Affiliation(s)
- H A Watkins
- School of Biological Sciences, University of Auckland, Auckland, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland, New Zealand
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Watkins HA, Au M, Bobby R, Archbold JK, Abdul-Manan N, Moore JM, Middleditch MJ, Williams GM, Brimble MA, Dingley AJ, Hay DL. Identification of key residues involved in adrenomedullin binding to the AM1 receptor. Br J Pharmacol 2014; 169:143-55. [PMID: 23351143 DOI: 10.1111/bph.12118] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Revised: 12/11/2012] [Accepted: 01/07/2013] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE Adrenomedullin (AM) is a peptide hormone whose receptors are members of the class B GPCR family. They comprise a heteromer between the GPCR, the calcitonin receptor-like receptor and one of the receptor activity-modifying proteins 1-3. AM plays a significant role in angiogenesis and its antagonist fragment AM22-52 can inhibit blood vessel and tumour growth. The mechanism by which AM interacts with its receptors is unknown. EXPERIMENTAL APPROACH We determined the AM22-52 binding epitope for the AM1 receptor extracellular domain using biophysical techniques, heteronuclear magnetic resonance spectroscopy and alanine scanning. KEY RESULTS Chemical shift perturbation experiments located the main binding epitope for AM22-52 at the AM1 receptor to the C-terminal 8 amino acids. Isothermal titration calorimetry of AM22-52 alanine-substituted peptides indicated that Y52, G51 and I47 are essential for AM1 receptor binding and that K46 and P49 and R44 have a smaller role to play. Characterization of these peptides at the full-length AM receptors was assessed in Cos7 cells by cAMP assay. This confirmed the essential role of Y52, G51 and I47 in binding to the AM1 receptor, with their substitution resulting in ≥100-fold reduction in antagonist potency compared with AM22-52 . R44A, K46A, S48A and P49A AM22-52 decreased antagonist potency by approximately 10-fold. CONCLUSIONS AND IMPLICATIONS This study localizes the main binding epitope of AM22-52 to its C-terminal amino acids and distinguishes essential residues involved in this binding. This will inform the development of improved AM receptor antagonists.
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Affiliation(s)
- H A Watkins
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
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Watkins HA, Rathbone DL, Barwell J, Hay DL, Poyner DR. Structure-activity relationships for α-calcitonin gene-related peptide. Br J Pharmacol 2013; 170:1308-22. [PMID: 23186257 PMCID: PMC3838678 DOI: 10.1111/bph.12072] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Revised: 10/11/2012] [Accepted: 11/15/2012] [Indexed: 12/30/2022] Open
Abstract
UNLABELLED Calcitonin gene-related peptide (CGRP) is a member of the calcitonin (CT) family of peptides. It is a widely distributed neuropeptide implicated in conditions such as neurogenic inflammation. With other members of the CT family, it shares an N-terminal disulphide-bonded ring which is essential for biological activity, an area of potential α-helix, and a C-terminal amide. CGRP binds to the calcitonin receptor-like receptor (CLR) in complex with receptor activity-modifying protein 1 (RAMP1), a member of the family B (or secretin-like) GPCRs. It can also activate other CLR or calcitonin-receptor/RAMP complexes. This 37 amino acid peptide comprises the N-terminal ring that is required for receptor activation (residues 1-7); an α-helix (residues 8-18), a region incorporating a β-bend (residues 19-26) and the C-terminal portion (residues 27-37), that is characterized by bends between residues 28-30 and 33-34. A few residues have been identified that seem to make major contributions to receptor binding and activation, with a larger number contributing either to minor interactions (which collectively may be significant), or to maintaining the conformation of the bound peptide. It is not clear if CGRP follows the pattern of other family B GPCRs in binding largely as an α-helix. LINKED ARTICLES This article is part of a themed section on Neuropeptides. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2013.170.issue-7.
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Affiliation(s)
- Harriet A Watkins
- School of Biological Sciences, University of AucklandAuckland, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, University of AucklandAuckland, New Zealand
| | - Dan L Rathbone
- School of Life and Health Sciences, Aston UniversityBirmingham, UK
| | - James Barwell
- School of Life and Health Sciences, Aston UniversityBirmingham, UK
| | - Debbie L Hay
- School of Biological Sciences, University of AucklandAuckland, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, University of AucklandAuckland, New Zealand
| | - David R Poyner
- School of Life and Health Sciences, Aston UniversityBirmingham, UK
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Woolley MJ, Watkins HA, Taddese B, Karakullukcu ZG, Barwell J, Smith KJ, Hay DL, Poyner DR, Reynolds CA, Conner AC. The role of ECL2 in CGRP receptor activation: a combined modelling and experimental approach. J R Soc Interface 2013; 10:20130589. [PMID: 24047872 PMCID: PMC3785825 DOI: 10.1098/rsif.2013.0589] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The calcitonin gene-related peptide (CGRP) receptor is a complex of a calcitonin receptor-like receptor (CLR), which is a family B G-protein-coupled receptor (GPCR) and receptor activity modifying protein 1. The role of the second extracellular loop (ECL2) of CLR in binding CGRP and coupling to Gs was investigated using a combination of mutagenesis and modelling. An alanine scan of residues 271–294 of CLR showed that the ability of CGRP to produce cAMP was impaired by point mutations at 13 residues; most of these also impaired the response to adrenomedullin (AM). These data were used to select probable ECL2-modelled conformations that are involved in agonist binding, allowing the identification of the likely contacts between the peptide and receptor. The implications of the most likely structures for receptor activation are discussed.
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Qi T, Dong M, Watkins HA, Wootten D, Miller LJ, Hay DL. Receptor activity-modifying protein-dependent impairment of calcitonin receptor splice variant Δ(1-47)hCT((a)) function. Br J Pharmacol 2013; 168:644-57. [PMID: 22946511 DOI: 10.1111/j.1476-5381.2012.02197.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Revised: 08/07/2012] [Accepted: 08/10/2012] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND AND PURPOSE Alternative splicing expands proteome diversity to GPCRs. Distinct receptor variants have been identified for a secretin family GPCR, the calcitonin receptor (CTR). The possible functional contributions of these receptor variants are further altered by their potential interactions with receptor activity-modifying proteins (RAMPs). One variant of the human CTR lacks the first 47 residues at its N terminus [Δ(1-47)hCT((a)) ]. However, very little is known about the pharmacology of this variant or its ability to interact with RAMPs to form amylin receptors. EXPERIMENTAL APPROACH Δ(1-47)hCT((a)) was characterized both with and without RAMPs in Cos7 and/or HEK293S cells. The receptor expression (ELISA assays) and function (cAMP and pERK1/2 assays) for up to six agonists and two antagonists were determined. KEY RESULTS Despite lacking 47 residues at the N terminus, Δ(1-47)hCT((a)) was still able to express at the cell surface, but displayed a generalized reduction in peptide potency. Δ(1-47)hCT((a)) retained its ability to interact with RAMP1 and formed a functional amylin receptor; this also appeared to be the case with RAMP3. On the other hand, its interaction with RAMP2 and resultant amylin receptor was reduced to a greater extent. CONCLUSIONS AND IMPLICATIONS Δ(1-47)hCT((a)) acts as a functional receptor at the cell surface. It exhibits altered receptor function, depending on whether it associates with a RAMP and which RAMP it interacts with. Therefore, the presence of this variant in tissues will potentially contribute to altered peptide binding and signalling, depending on the RAMP distribution in tissues.
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Affiliation(s)
- T Qi
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
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Watkins HA, Au M, Hay DL. Corrigendum to “The structure of secretin family GPCR peptide ligands: implications for receptor pharmacology and drug development” [Drug Discov. Today 17 (17–18) (2012) 1006–1014]. Drug Discov Today 2013. [DOI: 10.1016/j.drudis.2013.01.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Barwell J, Gingell JJ, Watkins HA, Archbold JK, Poyner DR, Hay DL. Calcitonin and calcitonin receptor-like receptors: common themes with family B GPCRs? Br J Pharmacol 2012; 166:51-65. [PMID: 21649645 DOI: 10.1111/j.1476-5381.2011.01525.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The calcitonin receptor (CTR) and calcitonin receptor-like receptor (CLR) are two of the 15 human family B (or Secretin-like) GPCRs. CTR and CLR are of considerable biological interest as their pharmacology is moulded by interactions with receptor activity-modifying proteins. They also have therapeutic relevance for many conditions, such as osteoporosis, diabetes, obesity, lymphatic insufficiency, migraine and cardiovascular disease. In light of recent advances in understanding ligand docking and receptor activation in both the family as a whole and in CLR and CTR specifically, this review reflects how applicable general family B GPCR themes are to these two idiosyncratic receptors. We review the main functional domains of the receptors; the N-terminal extracellular domain, the juxtamembrane domain and ligand interface, the transmembrane domain and the intracellular C-terminal domain. Structural and functional findings from the CLR and CTR along with other family B GPCRs are critically appraised to gain insight into how these domains may function. The ability for CTR and CLR to interact with receptor activity-modifying proteins adds another level of sophistication to these receptor systems but means careful consideration is needed when trying to apply generic GPCR principles. This review encapsulates current thinking in the realm of family B GPCR research by highlighting both conflicting and recurring themes and how such findings relate to two unusual but important receptors, CTR and CLR.
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Affiliation(s)
- James Barwell
- School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham, UK
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Watkins HA, Hay DL. Recent progress in unraveling the complexities of receptor biology: towards new therapeutics. Expert Rev Clin Pharmacol 2012; 5:145-7. [DOI: 10.1586/ecp.12.11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Watkins HA, Baker EN. Cloning, expression, purification and preliminary crystallographic analysis of the RNase HI domain of the Mycobacterium tuberculosis protein Rv2228c as a maltose-binding protein fusion. Acta Crystallogr Sect F Struct Biol Cryst Commun 2008; 64:746-9. [PMID: 18678948 PMCID: PMC2494979 DOI: 10.1107/s1744309108021118] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2008] [Accepted: 07/08/2008] [Indexed: 11/10/2022]
Abstract
The predicted ribonuclease (RNase) HI domain of the open reading frame Rv2228c from Mycobacterium tuberculosis has been cloned as a hexahistidine fusion and a maltose-binding protein (MBP) fusion. Expression was only observed for the MBP-fusion protein, which was purified using amylose affinity chromatography and gel filtration. The RNase HI domain could be cleaved from the MBP-fusion protein by factor Xa digestion, but was very unstable. In contrast, the fusion protein was stable, could be obtained in high yield and gave crystals which diffracted to 2.25 A resolution. The crystals belong to space group P2(1) and have unit-cell parameters a = 73.63, b = 101.38, c = 76.09 A, beta = 109.0 degrees. Two fusion-protein molecules of 57,417 Da were present in each asymmetric unit.
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Affiliation(s)
- Harriet A Watkins
- Maurice Wilkins Centre for Molecular Biodiscovery and School of Biological Sciences, 3A Symonds Street, Private Bag 92019, Auckland, New Zealand.
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Watkins HA, Baker EN. Structural and functional analysis of Rv3214 from Mycobacterium tuberculosis, a protein with conflicting functional annotations, leads to its characterization as a phosphatase. J Bacteriol 2006; 188:3589-99. [PMID: 16672613 PMCID: PMC1482868 DOI: 10.1128/jb.188.10.3589-3599.2006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The availability of complete genome sequences has highlighted the problems of functional annotation of the many gene products that have only limited sequence similarity with proteins of known function. The predicted protein encoded by open reading frame Rv3214 from the Mycobacterium tuberculosis H37Rv genome was originally annotated as EntD through sequence similarity with the Escherichia coli EntD, a 4'-phosphopantetheinyl transferase implicated in siderophore biosynthesis. An alternative annotation, based on slightly higher sequence identity, grouped Rv3214 with proteins of the cofactor-dependent phosphoglycerate mutase (dPGM) family. The crystal structure of this protein has been solved by single-wavelength anomalous dispersion methods and refined at 2.07-Angstroms resolution (R = 0.229; R(free) = 0.245). The protein is dimeric, with a monomer fold corresponding to the classical dPGM alpha/beta structure, albeit with some variations. Closer comparisons of structure and sequence indicate that it most closely corresponds with a broad-spectrum phosphatase subfamily within the dPGM superfamily. This functional annotation has been confirmed by biochemical assays which show negligible mutase activity but acid phosphatase activity with a pH optimum of 5.4 and suggests that Rv3214 may be important for mycobacterial phosphate metabolism in vivo. Despite its weak sequence similarity with the 4'-phosphopantetheinyl transferases (EntD homologues), there is little evidence to support this function.
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Affiliation(s)
- Harriet A Watkins
- Centre for Molecular Biodiscovery and School of Biological Sciences, University of Auckland, New Zealand
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Watkins HA, Yu M, Baker EN. Cloning, expression, purification and preliminary crystallographic data for Rv3214 (EntD), a predicted cofactor-dependent phosphoglycerate mutase from Mycobacterium tuberculosis. Acta Crystallogr Sect F Struct Biol Cryst Commun 2005; 61:753-5. [PMID: 16511148 PMCID: PMC1952354 DOI: 10.1107/s1744309105020646] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2005] [Accepted: 06/28/2005] [Indexed: 11/10/2022]
Abstract
The Mycobacterium tuberculosis open reading frame Rv3214, annotated as a cofactor-dependent phosphoglycerate mutase, has been cloned and expressed as an N-terminally His-tagged protein. Tagged, untagged and selenomethionine-labelled forms of Rv3214 (EntD) have been purified using nickel-affinity chromatography and gel filtration. The selenomethionine-labelled crystals diffracted to 2.15 A resolution and belong to space group P2(1), with unit-cell parameters a = 44.36, b = 79.03, c = 52.85 A, beta = 109.11 degrees. There are two molecules of molecular weight 21,948 Da per asymmetric unit.
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Affiliation(s)
- Harriet A Watkins
- Centre for Molecular Biodiscovery, School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand.
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