1
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Cardoso JCR, Félix RC, Ferreira V, Peng M, Zhang X, Power DM. The calcitonin-like system is an ancient regulatory system of biomineralization. Sci Rep 2020; 10:7581. [PMID: 32371888 PMCID: PMC7200681 DOI: 10.1038/s41598-020-64118-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 04/06/2020] [Indexed: 12/27/2022] Open
Abstract
Biomineralization is the process by which living organisms acquired the capacity to accumulate minerals in tissues. Shells are the biomineralized exoskeleton of marine molluscs produced by the mantle but factors that regulate mantle shell building are still enigmatic. This study sought to identify candidate regulatory factors of molluscan shell mineralization and targeted family B G-protein coupled receptors (GPCRs) and ligands that include calcium regulatory factors in vertebrates, such as calcitonin (CALC). In molluscs, CALC receptor (CALCR) number was variable and arose through lineage and species-specific duplications. The Mediterranean mussel (Mytilus galloprovincialis) mantle transcriptome expresses six CALCR-like and two CALC-precursors encoding four putative mature peptides. Mussel CALCR-like are activated in vitro by vertebrate CALC but only receptor CALCRIIc is activated by the mussel CALCIIa peptide (EC50 = 2.6 ×10-5 M). Ex-vivo incubations of mantle edge tissue and mantle cells with CALCIIa revealed they accumulated significantly more calcium than untreated tissue and cells. Mussel CALCIIa also significantly decreased mantle acid phosphatase activity, which is associated with shell remodelling. Our data indicate the CALC-like system as candidate regulatory factors of shell mineralization. The identification of the CALC system from molluscs to vertebrates suggests it is an ancient and conserved calcium regulatory system of mineralization.
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Affiliation(s)
- João C R Cardoso
- Comparative Endocrinology and Integrative Biology, Centre of Marine Sciences, Universidade do Algarve, Campus de Gambelas, 8005-139, Faro, Portugal.
| | - Rute C Félix
- Comparative Endocrinology and Integrative Biology, Centre of Marine Sciences, Universidade do Algarve, Campus de Gambelas, 8005-139, Faro, Portugal
| | - Vinícius Ferreira
- Comparative Endocrinology and Integrative Biology, Centre of Marine Sciences, Universidade do Algarve, Campus de Gambelas, 8005-139, Faro, Portugal
| | - MaoXiao Peng
- Comparative Endocrinology and Integrative Biology, Centre of Marine Sciences, Universidade do Algarve, Campus de Gambelas, 8005-139, Faro, Portugal
| | - Xushuai Zhang
- Comparative Endocrinology and Integrative Biology, Centre of Marine Sciences, Universidade do Algarve, Campus de Gambelas, 8005-139, Faro, Portugal
| | - Deborah M Power
- Comparative Endocrinology and Integrative Biology, Centre of Marine Sciences, Universidade do Algarve, Campus de Gambelas, 8005-139, Faro, Portugal.
- International Research Center for Marine Biosciences, Ministry of Science and Technology, Shanghai Ocean University, Shanghai, China.
- Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai, China.
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2
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Liang YL, Belousoff MJ, Fletcher MM, Zhang X, Khoshouei M, Deganutti G, Koole C, Furness SGB, Miller LJ, Hay DL, Christopoulos A, Reynolds CA, Danev R, Wootten D, Sexton PM. Structure and Dynamics of Adrenomedullin Receptors AM 1 and AM 2 Reveal Key Mechanisms in the Control of Receptor Phenotype by Receptor Activity-Modifying Proteins. ACS Pharmacol Transl Sci 2020; 3:263-284. [PMID: 32296767 PMCID: PMC7155201 DOI: 10.1021/acsptsci.9b00080] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Indexed: 12/14/2022]
Abstract
Adrenomedullin (AM) and calcitonin gene-related peptide (CGRP) receptors are critically important for metabolism, vascular tone, and inflammatory response. AM receptors are also required for normal lymphatic and blood vascular development and angiogenesis. They play a pivotal role in embryo implantation and fertility and can provide protection against hypoxic and oxidative stress. CGRP and AM receptors are heterodimers of the calcitonin receptor-like receptor (CLR) and receptor activity-modifying protein 1 (RAMP1) (CGRPR), as well as RAMP2 or RAMP3 (AM1R and AM2R, respectively). However, the mechanistic basis for RAMP modulation of CLR phenotype is unclear. In this study, we report the cryo-EM structure of the AM1R in complex with AM and Gs at a global resolution of 3.0 Å, and structures of the AM2R in complex with either AM or intermedin/adrenomedullin 2 (AM2) and Gs at 2.4 and 2.3 Å, respectively. The structures reveal distinctions in the primary orientation of the extracellular domains (ECDs) relative to the receptor core and distinct positioning of extracellular loop 3 (ECL3) that are receptor-dependent. Analysis of dynamic data present in the cryo-EM micrographs revealed additional distinctions in the extent of mobility of the ECDs. Chimeric exchange of the linker region of the RAMPs connecting the TM helix and the ECD supports a role for this segment in controlling receptor phenotype. Moreover, a subset of the motions of the ECD appeared coordinated with motions of the G protein relative to the receptor core, suggesting that receptor ECD dynamics could influence G protein interactions. This work provides fundamental advances in our understanding of GPCR function and how this can be allosterically modulated by accessory proteins.
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Affiliation(s)
- Yi-Lynn Liang
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Matthew J. Belousoff
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Madeleine M. Fletcher
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Xin Zhang
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Maryam Khoshouei
- Department
of Molecular Structural Biology, Max Planck
Institute of Biochemistry, 82152 Martinsried, Germany
| | - Giuseppe Deganutti
- School
of Biological Sciences, University of Essex, Colchester CO4 3SQ, United Kingdom
| | - Cassandra Koole
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Sebastian G. B. Furness
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | - Laurence J. Miller
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
- Department
of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, Arizona 85259, United States
| | - Debbie L. Hay
- School
of Biological Sciences, and Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland 1142, New Zealand
| | - Arthur Christopoulos
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
| | | | - Radostin Danev
- Graduate
School of Medicine, University of Tokyo, S402, 7-3-1 Hongo, Bunkyo-ku, 113-0033 Tokyo, Japan
| | - Denise Wootten
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
- School
of Pharmacy, Fudan University, Shanghai 201203, China
| | - Patrick M. Sexton
- Drug
Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Victoria, Australia
- School
of Pharmacy, Fudan University, Shanghai 201203, China
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3
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Simms J, Uddin R, Sakmar TP, Gingell JJ, Garelja ML, Hay DL, Brimble MA, Harris PW, Reynolds CA, Poyner DR. Photoaffinity Cross-Linking and Unnatural Amino Acid Mutagenesis Reveal Insights into Calcitonin Gene-Related Peptide Binding to the Calcitonin Receptor-like Receptor/Receptor Activity-Modifying Protein 1 (CLR/RAMP1) Complex. Biochemistry 2018; 57:4915-4922. [PMID: 30004692 DOI: 10.1021/acs.biochem.8b00502] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Calcitonin gene-related peptide (CGRP) binds to the complex of the calcitonin receptor-like receptor (CLR) with receptor activity-modifying protein 1 (RAMP1). How CGRP interacts with the transmembrane domain (including the extracellular loops) of this family B receptor remains unclear. In this study, a photoaffinity cross-linker, p-azido l-phenylalanine (azF), was incorporated into CLR, chiefly in the second extracellular loop (ECL2) using genetic code expansion and unnatural amino acid mutagenesis. The method was optimized to ensure efficient photolysis of azF residues near the transmembrane bundle of the receptor. A CGRP analogue modified with fluorescein at position 15 was used for detection of ultraviolet-induced cross-linking. The methodology was verified by confirming the known contacts of CGRP to the extracellular domain of CLR. Within ECL2, the chief contacts were I284 on the loop itself and L291, at the top of the fifth transmembrane helix (TM5). Minor contacts were noted along the lip of ECL2 between S286 and L290 and also with M223 in TM3 and F349 in TM6. Full length molecular models of the bound receptor complex suggest that CGRP sits at the top of the TM bundle, with Thr6 of the peptide making contacts with L291 and H295. I284 is likely to contact Leu12 and Ala13 of CGRP, and Leu16 of CGRP is at the ECL/extracellular domain boundary of CLR. The reduced potency, Emax, and affinity of [Leu16Ala]-human α CGRP are consistent with this model. Contacts between Thr6 of CGRP and H295 may be particularly important for receptor activation.
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Affiliation(s)
- John Simms
- Aston University , Birmingham B4 7ET , U.K
- Coventry University , Priory Street , Coventry CV1 5FB , U.K
| | | | - Thomas P Sakmar
- The Rockefeller University , 1230 York Avenue , New York , New York 10065 , United States
| | - Joseph J Gingell
- University of Auckland , 3A Symonds Street , Auckland 1010 , New Zealand
| | - Michael L Garelja
- University of Auckland , 3A Symonds Street , Auckland 1010 , New Zealand
| | - Debbie L Hay
- University of Auckland , 3A Symonds Street , Auckland 1010 , New Zealand
| | - Margaret A Brimble
- University of Auckland , 3A Symonds Street , Auckland 1010 , New Zealand
| | - Paul W Harris
- University of Auckland , 3A Symonds Street , Auckland 1010 , New Zealand
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4
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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] [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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5
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Culhane KJ, Liu Y, Cai Y, Yan ECY. Transmembrane signal transduction by peptide hormones via family B G protein-coupled receptors. Front Pharmacol 2015; 6:264. [PMID: 26594176 PMCID: PMC4633518 DOI: 10.3389/fphar.2015.00264] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 10/23/2015] [Indexed: 01/28/2023] Open
Abstract
Although family B G protein-coupled receptors (GPCRs) contain only 15 members, they play key roles in transmembrane signal transduction of hormones. Family B GPCRs are drug targets for developing therapeutics for diseases ranging from metabolic to neurological disorders. Despite their importance, the molecular mechanism of activation of family B GPCRs remains largely unexplored due to the challenges in expression and purification of functional receptors to the quantity for biophysical characterization. Currently, there is no crystal structure available of a full-length family B GPCR. However, structures of key domains, including the extracellular ligand binding regions and seven-helical transmembrane regions, have been solved by X-ray crystallography and NMR, providing insights into the mechanisms of ligand recognition and selectivity, and helical arrangements within the cell membrane. Moreover, biophysical and biochemical methods have been used to explore functions, key residues for signaling, and the kinetics and dynamics of signaling processes. This review summarizes the current knowledge of the signal transduction mechanism of family B GPCRs at the molecular level and comments on the challenges and outlook for mechanistic studies of family B GPCRs.
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Affiliation(s)
- Kelly J Culhane
- Department of Molecular Biophysics and Biochemistry, Yale University New Haven, CT, USA
| | - Yuting Liu
- Department of Chemistry, Yale University New Haven, CT, USA
| | - Yingying Cai
- Department of Chemistry, Yale University New Haven, CT, USA
| | - Elsa C Y Yan
- Department of Chemistry, Yale University New Haven, CT, USA
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6
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Booe J, Walker CS, Barwell J, Kuteyi G, Simms J, Jamaluddin M, Warner M, Bill R, Harris P, Brimble M, Poyner D, Hay D, Pioszak A. Structural Basis for Receptor Activity-Modifying Protein-Dependent Selective Peptide Recognition by a G Protein-Coupled Receptor. Mol Cell 2015; 58:1040-52. [PMID: 25982113 PMCID: PMC4504005 DOI: 10.1016/j.molcel.2015.04.018] [Citation(s) in RCA: 97] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Revised: 03/23/2015] [Accepted: 04/09/2015] [Indexed: 01/07/2023]
Abstract
Association of receptor activity-modifying proteins (RAMP1-3) with the G protein-coupled receptor (GPCR) calcitonin receptor-like receptor (CLR) enables selective recognition of the peptides calcitonin gene-related peptide (CGRP) and adrenomedullin (AM) that have diverse functions in the cardiovascular and lymphatic systems. How peptides selectively bind GPCR:RAMP complexes is unknown. We report crystal structures of CGRP analog-bound CLR:RAMP1 and AM-bound CLR:RAMP2 extracellular domain heterodimers at 2.5 and 1.8 Å resolutions, respectively. The peptides similarly occupy a shared binding site on CLR with conformations characterized by a β-turn structure near their C termini rather than the α-helical structure common to peptides that bind related GPCRs. The RAMPs augment the binding site with distinct contacts to the variable C-terminal peptide residues and elicit subtly different CLR conformations. The structures and accompanying pharmacology data reveal how a class of accessory membrane proteins modulate ligand binding of a GPCR and may inform drug development targeting CLR:RAMP complexes.
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Affiliation(s)
- Jason M. Booe
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Christopher S. Walker
- School of Biological Sciences and Maurice Wilkins Centre, University of Auckland, Auckland 1142, New Zealand
| | - James Barwell
- School of Life and Health Sciences, Aston University, Birmingham, B4 7ET, UK
| | - Gabriel Kuteyi
- School of Life and Health Sciences, Aston University, Birmingham, B4 7ET, UK
| | - John Simms
- School of Life and Health Sciences, Aston University, Birmingham, B4 7ET, UK
| | - Muhammad A. Jamaluddin
- School of Biological Sciences and Maurice Wilkins Centre, University of Auckland, Auckland 1142, New Zealand
| | - Margaret L. Warner
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Roslyn M. Bill
- School of Life and Health Sciences, Aston University, Birmingham, B4 7ET, UK
| | - Paul W. Harris
- School of Chemical Sciences and Maurice Wilkins Centre, University of Auckland, Auckland 1142, New Zealand
| | - Margaret A. Brimble
- School of Chemical Sciences and Maurice Wilkins Centre, University of Auckland, Auckland 1142, New Zealand
| | - David R. Poyner
- School of Life and Health Sciences, Aston University, Birmingham, B4 7ET, UK
| | - Debbie L. Hay
- School of Biological Sciences and Maurice Wilkins Centre, University of Auckland, Auckland 1142, New Zealand
| | - Augen A. Pioszak
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA,Corresponding author
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7
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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] [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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8
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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] [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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9
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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] [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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10
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Abstract
The CGRP (calcitonin gene-related peptide) receptor is a family B GPCR (G-protein-coupled receptor). It consists of a GPCR, CLR (calcitonin receptor-like receptor) and an accessory protein, RAMP1 (receptor activity modifying protein 1). RAMP1 is needed for CGRP binding and also cell-surface expression of CLR. CLR is an example of a family B GPCR. Unlike family A GPCRs, little is known about how these receptors are activated by their endogenous ligands. This review considers what is known about the activation of family B GPCRs and then considers how this might be applied to CLR, particularly in light of new knowledge of the crystal structures of family A GPCRs.
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11
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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] [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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12
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Parameswaran N, Spielman WS. Introduction to RAMPs. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 744:1-11. [PMID: 22434103 DOI: 10.1007/978-1-4614-2364-5_1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Receptor activity modifying proteins (RAMPs) are single transmembrane proteins discovered for their role in the regulation of translocation of certain G-protein coupled receptors (GPCRs) to the plasma membrane. Since its discovery in 1998, several pivotal advances have been made in understanding the function of this family of proteins. This chapter provides a basic introduction to RAMPs as well as details on the various chapters in this book.
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Structural insights into RAMP modification of secretin family G protein-coupled receptors: implications for drug development. Trends Pharmacol Sci 2011; 32:591-600. [DOI: 10.1016/j.tips.2011.05.007] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Revised: 05/25/2011] [Accepted: 05/26/2011] [Indexed: 11/18/2022]
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Kuwasako K, Kitamura K, Nagata S, Hikosaka T, Takei Y, Kato J. Shared and separate functions of the RAMP-based adrenomedullin receptors. Peptides 2011; 32:1540-50. [PMID: 21645567 DOI: 10.1016/j.peptides.2011.05.022] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Revised: 05/20/2011] [Accepted: 05/20/2011] [Indexed: 11/25/2022]
Abstract
Adrenomedullin (AM) is a novel hypotensive peptide that exerts a variety of strongly protective effects against multiorgan damage. AM-specific receptors were first identified as heterodimers composed of calcitonin-receptor-like receptor (CLR), a G protein coupled receptor, and one of two receptor activity-modifying proteins (RAMP2 or RAMP3), which are accessory proteins containing a single transmembrane domain. RAMPs are required for the surface delivery of CLR and the determination of its phenotype. CLR/RAMP2 (AM₁ receptor) is more highly AM-specific than CLR/RAMP3 (AM₂ receptor). Although there have been no reports showing differences in intracellular signaling via the two AM receptors, in vitro studies have shed light on their distinct trafficking and functionality. In addition, the tissue distributions of RAMP2 and RAMP3 differ, and their gene expression is differentially altered under pathophysiological conditions, which is suggestive of the separate roles played by AM₁ and AM₂ receptors in vivo. Both AM and the AM₁ receptor, but not the AM₂ receptor, are crucial for the development of the fetal cardiovascular system and are able to effectively protect against various vascular diseases. However, AM₂ receptors reportedly play an important role in maintaining a normal body weight in old age and may be involved in immune function. In this review article, we focus on the shared and separate functions of the AM receptor subtypes and also discuss the potential for related drug discovery. In addition, we mention their possible function as receptors for AM2 (or intermedin), an AM-related peptide whose biological functions are similar to those of AM.
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Affiliation(s)
- Kenji Kuwasako
- Frontier Science Research Center, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki, Miyazaki 889-1692, Japan.
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Barwell J, Conner A, Poyner DR. Extracellular loops 1 and 3 and their associated transmembrane regions of the calcitonin receptor-like receptor are needed for CGRP receptor function. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2011; 1813:1906-16. [PMID: 21703310 PMCID: PMC3228915 DOI: 10.1016/j.bbamcr.2011.06.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/21/2011] [Revised: 05/31/2011] [Accepted: 06/08/2011] [Indexed: 12/30/2022]
Abstract
The first and third extracellular loops (ECL) of G protein-coupled receptors (GPCRs) have been implicated in ligand binding and receptor function. This study describes the results of an alanine/leucine scan of ECLs 1 and 3 and loop-associated transmembrane (TM) domains of the secretin-like GPCR calcitonin receptor-like receptor which associates with receptor activity modifying protein 1 to form the CGRP receptor. Leu195Ala, Val198Ala and Ala199Leu at the top of TM2 all reduced αCGRP-mediated cAMP production and internalization; Leu195Ala and Ala199Leu also reduced αCGRP binding. These residues form a hydrophobic cluster within an area defined as the “minor groove” of rhodopsin-like GPCRs. Within ECL1, Ala203Leu and Ala206Leu influenced the ability of αCGRP to stimulate adenylate cyclase. In TM3, His219Ala, Leu220Ala and Leu222Ala have influences on αCGRP binding and cAMP production; they are likely to indirectly influence the binding site for αCGRP as well as having an involvement in signal transduction. On the exofacial surfaces of TMs 6 and 7, a number of residues were identified that reduced cell surface receptor expression, most noticeably Leu351Ala and Glu357Ala in TM6. The residues may contribute to the RAMP1 binding interface. Ile360Ala impaired αCGRP-mediated cAMP production. Ile360 is predicted to be located close to ECL2 and may facilitate receptor activation. Identification of several crucial functional loci gives further insight into the activation mechanism of this complex receptor system and may aid rational drug design.
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Affiliation(s)
- James Barwell
- School of Life and Health Sciences, Aston University, Birmingham, B4 7ET, UK.
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16
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Qi T, Ly K, Poyner DR, Christopoulos G, Sexton PM, Hay DL. Structure-function analysis of amino acid 74 of human RAMP1 and RAMP3 and its role in peptide interactions with adrenomedullin and calcitonin gene-related peptide receptors. Peptides 2011; 32:1060-7. [PMID: 21402116 DOI: 10.1016/j.peptides.2011.03.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2010] [Revised: 03/03/2011] [Accepted: 03/03/2011] [Indexed: 11/28/2022]
Abstract
The receptors for calcitonin gene-related peptide (CGRP) and adrenomedullin (AM) are complexes of the calcitonin receptor-like receptor (CLR) and receptor activity-modifying proteins (RAMP). The CGRP receptor is a CLR/RAMP1 pairing whereas CLR/RAMP2 and CLR/RAMP3 constitute two subtypes of AM receptor: AM(1) and AM(2), respectively. Previous studies identified Glu74 in RAMP3 to be important for AM binding and potency. To further understand the importance of this residue and its equivalent in RAMP1 (Trp74) we substituted the native amino acids with several others. In RAMP3, these were Trp, Phe, Tyr, Ala, Ser, Thr, Arg and Asn; in RAMP1, Glu, Phe, Tyr, Ala and Asn substitutions were made. The mutant RAMPs were co-expressed with CLR in Cos7 cells; receptor function in response to AM, AM(2)/intermedin and CGRP was measured in a cAMP assay and cell surface expression was determined by ELISA. Phe reduced AM potency in RAMP3 but had no effect in RAMP1. In contrast, Tyr had no effect in RAMP3 but enhanced AM potency in RAMP1. Most other substitutions had a small effect on AM potency in both receptors whereas there was little impact on CGRP or AM(2) potency. Overall, these data suggest that the geometry and charge of the residue at position 74 contribute to how AM interacts with the AM(2) and CGRP receptors and confirms the role of this position in dictating differential AM pharmacology at the AM(2) and CGRP receptors.
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Affiliation(s)
- Tao Qi
- School of Biological Sciences, University of Auckland, Auckland, New Zealand.
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17
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Crystal structure of the ectodomain complex of the CGRP receptor, a class-B GPCR, reveals the site of drug antagonism. Structure 2011; 18:1083-93. [PMID: 20826335 DOI: 10.1016/j.str.2010.05.014] [Citation(s) in RCA: 134] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2010] [Revised: 05/21/2010] [Accepted: 05/25/2010] [Indexed: 11/22/2022]
Abstract
Dysregulation of the calcitonin gene-related peptide (CGRP), a potent vasodilator, is directly implicated in the pathogenesis of migraine. CGRP binds to and signals through the CGRP receptor (CGRP-R), a heterodimer containing the calcitonin receptor-like receptor (CLR), a class B GPCR, and RAMP1, a receptor activity-modifying protein. We have solved the crystal structure of the CLR/RAMP1 N-terminal ectodomain heterodimer, revealing how RAMPs bind to and potentially modulate the activities of the CLR GPCR subfamily. We also report the structures of CLR/RAMP1 in complex with the clinical receptor antagonists olcegepant (BIBN4096BS) and telcagepant (MK0974). Both drugs act by blocking access to the peptide-binding cleft at the interface of CLR and RAMP1. These structures illustrate, for the first time, how small molecules bind to and modulate the activity of a class B GPCR, and highlight the challenges of designing potent receptor antagonists for the treatment of migraine and other class B GPCR-related diseases.
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Fischer MJM. Calcitonin gene-related peptide receptor antagonists for migraine. Expert Opin Investig Drugs 2010; 19:815-23. [PMID: 20482328 DOI: 10.1517/13543784.2010.490829] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
IMPORTANCE OF THE FIELD Migraine is a highly prevalent disabling condition, and the current treatment options are not satisfactory. The role of calcitonin gene-related peptide (CGRP) in migraine pathophysiology is well established. CGRP receptor antagonists address this new target and have the potential to improve therapy for both responders and non-responders to previous options. AREAS COVERED IN THIS REVIEW This review describes CGRP, its receptors and their role in the pathophysiology of migraine. CGRP receptor antagonists are a recent development; all reported antagonists are reported in chronological order. The experimental evidence, as well as all clinical trials since the first proof-of-concept study in 2004, is discussed. WHAT THE READER WILL GAIN An overview of the CGRP system and why it provides an attractive drug target for headache. The main focus is on the currently presented CGRP receptor antagonists and clinical evidence for this new therapeutic option. TAKE HOME MESSAGE CGRP receptor antagonists will provide an additional and valuable therapeutic option for the treatment of headaches.
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Koth CM, Abdul-Manan N, Lepre CA, Connolly PJ, Yoo S, Mohanty AK, Lippke JA, Zwahlen J, Coll JT, Doran JD, Garcia-Guzman M, Moore JM. Refolding and characterization of a soluble ectodomain complex of the calcitonin gene-related peptide receptor. Biochemistry 2010; 49:1862-72. [PMID: 20099900 DOI: 10.1021/bi901848m] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The calcitonin gene-related peptide (CGRP) receptor is a heterodimer of two membrane proteins: calcitonin receptor-like receptor (CLR) and receptor activity-modifying protein 1 (RAMP1). CLR is a class B G-protein-coupled receptor (GPCR), possessing a characteristic large amino-terminal extracellular domain (ECD) important for ligand recognition and binding. Dimerization of CLR with RAMP1 provides specificity for CGRP versus related agonists. Here we report the expression, purification, and refolding of a soluble form of the CGRP receptor comprising a heterodimer of the CLR and RAMP1 ECDs. The extracellular protein domains corresponding to residues 23-133 of CLR and residues 26-117 of RAMP1 were shown to be sufficient for formation of a stable, monodisperse complex. The binding affinity of the purified ECD complex for the CGRP peptide was significantly lower than that of the native receptor (IC(50) of 12 microM for the purified ECD complex vs 233 pM for membrane-bound CGRP receptor), indicating that other regions of CLR and/or RAMP1 are important for peptide agonist binding. However, high-affinity binding to known potent and specific nonpeptide antagonists of the CGRP receptor, including olcegepant and telcagepant (K(D) < 0.02 muM), as well as N-terminally truncated peptides and peptide analogues (140 nM to 1.62 microM) was observed.
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Affiliation(s)
- Christopher M Koth
- Vertex Pharmaceuticals Inc., 130 Waverly Street, Cambridge, Massachusetts 02139, USA
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Wootten DL, Simms J, Hay DL, Christopoulos A, Sexton PM. Receptor activity modifying proteins and their potential as drug targets. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2010; 91:53-79. [PMID: 20691959 DOI: 10.1016/s1877-1173(10)91003-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The receptor activity modifying proteins (RAMPs) are a family of membrane proteins that interact with some G protein-coupled receptors (GPCRs) to regulate their function. RAMPs can alter GPCR pharmacology and can regulate their signaling as well as trafficking to and from the cell surface. GPCRs have been successfully exploited as drug targets for many years. RAMPs therefore provide a new avenue for drug development, offering opportunities for regulating the function of therapeutically relevant RAMP-interacting GPCRs. RAMPs could be directly targeted themselves or advantage could be taken of the unique RAMP/GPCR interfaces for generating more selective drugs.
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Affiliation(s)
- Denise L Wootten
- Drug Discovery Biology Laboratory, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
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