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Oral expressions and functional analyses of the extracellular calcium-sensing receptor (CaSR) in chicken. Sci Rep 2022; 12:17762. [PMID: 36273034 PMCID: PMC9588031 DOI: 10.1038/s41598-022-22512-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 10/17/2022] [Indexed: 01/19/2023] Open
Abstract
In vertebrates, the extracellular calcium-sensing receptor (CaSR) plays a key role in calcium homeostasis by sensing slight changes in extracellular Ca2+. CaSR is also expressed in mammals including rodent taste cells and is involved in sensing kokumi, a rich, savory quality that enhances the intensities of salty, sweet, and umami tastes. In this study, we focused on chicken CaSR (cCaSR) since calcium is an essential nutrient that is necessary for making eggshell and for the extremely rapid initial growth of bones. First we confirmed that cCaSR is expressed in taste cells. Next we cloned the cCaSR gene from kidney and transiently transfected human embryonic kidney 293 T (HEK293T) cells with the recombinant cCaSR, or empty vector and looked for the agonists and allosteric modulators (including kokumi substances) of cCaSR by Ca2+ imaging. We found that cCaSR was activated by extracellular Ca2+ and Mg2+ in a dose dependent manner. Several L-amino acids and kokumi substances such as glutathione enhanced the response of cCaSR. In addition, NPS2143 as a negative allosteric modulator of human CaSR negatively modulated the response of cCaSR. These results suggest that cCaSR can sense extracellular Ca2+ and Mg2+ as well as positive and negative allosteric modulators. Taken together, the results imply that CaSR might be a multifunctional receptor for calcium, amino acids, and kokumi substances in chicken. The present finding that functional CaSR is expressed in the chicken oral tissues will allow us to further elucidate the physiological role of CaSR in the chickens' taste sense, and to create new feeds that will contribute to the poultry industry.
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2
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Goolam MA, Brown AP, Edwards KT, Gregory KJ, Leach K, Conigrave AD. Cell Surface Calcium-Sensing Receptor Heterodimers: Mutant Gene Dosage Affects Ca 2+ Sensing but Not G Protein Interaction. J Bone Miner Res 2022; 37:1787-1807. [PMID: 35848051 PMCID: PMC9545990 DOI: 10.1002/jbmr.4651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 06/20/2022] [Accepted: 07/14/2022] [Indexed: 11/20/2022]
Abstract
The calcium-sensing receptor is a homodimeric class C G protein-coupled receptor (GPCR) that senses extracellular Ca2+ (Ca2+ o ) via a dimeric extracellular Venus flytrap (VFT) unit that activates G protein-dependent signaling via twin Cysteine-rich domains linked to transmembrane heptahelical (HH) bundles. It plays a key role in the regulation of human calcium and thus mineral metabolism. However, the nature of interactions between VFT units and HH bundles, and the impacts of heterozygous or homozygous inactivating mutations, which have implications for disorders of calcium metabolism are not yet clearly defined. Herein we generated CaSR-GABAB1 and CaSR-GABAB2 chimeras subject to GABAB -dependent endoplasmic reticulum sorting to traffic mutant heterodimers to the cell surface. Transfected HEK-293 cells were assessed for Ca2+ o -stimulated Ca2+ i mobilization using mutations in either the VFT domains and/or HH bundle intraloop-2 or intraloop-3. When the same mutation was present in both VFT domains of receptor dimers, analogous to homozygous neonatal severe hyperparathyroidism (NSHPT), receptor function was markedly impaired. Mutant heterodimers containing one wild-type (WT) and one mutant VFT domain, however, corresponding to heterozygous familial hypocalciuric hypercalcemia type-1 (FHH-1), supported maximal signaling with reduced Ca2+ o potency. Thus two WT VFT domains were required for normal Ca2+ o potency and there was a pronounced gene-dosage effect. In contrast, a single WT HH bundle was insufficient for maximal signaling and there was no functional difference between heterodimers in which the mutation was present in one or both intraloops; ie, no gene-dosage effect. Finally, we observed that the Ca2+ o -stimulated CaSR operated exclusively via signaling in-trans and not via combined in-trans and in-cis signaling. We consider how receptor asymmetry may support the underlying mechanisms. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Mahvash A Goolam
- School of Life and Environmental Sciences, Charles Perkins Centre (D17), University of Sydney, NSW, Australia
| | - Alice P Brown
- School of Life and Environmental Sciences, Charles Perkins Centre (D17), University of Sydney, NSW, Australia
| | - Kimberly T Edwards
- School of Life and Environmental Sciences, Charles Perkins Centre (D17), University of Sydney, NSW, Australia
| | - Karen J Gregory
- Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia
| | - Katie Leach
- Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia
| | - Arthur D Conigrave
- School of Life and Environmental Sciences, Charles Perkins Centre (D17), University of Sydney, NSW, Australia
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3
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Yang C, Rybchyn MS, De Silva WGM, Matthews J, Holland AJA, Conigrave AD, Mason RS. UV-induced DNA Damage in Skin is Reduced by CaSR Inhibition. Photochem Photobiol 2022; 98:1157-1166. [PMID: 35288938 PMCID: PMC9540002 DOI: 10.1111/php.13615] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 02/02/2022] [Indexed: 11/30/2022]
Abstract
The epidermis maintains a cellular calcium gradient that supports keratinocyte differentiation from its basal layers (low) to outer layers (high) leading to the development of the stratum corneum, which resists penetration of UV radiation. The calcium‐sensing receptor (CaSR) expressed in keratinocytes responds to the calcium gradient with signals that promote differentiation. In this study, we investigated whether the CaSR is involved more directly in protection from UV damage in studies of human keratinocytes in primary culture and in mouse skin studied in vivo. siRNA‐directed reductions in CaSR protein levels in human keratinocytes significantly reduced UV‐induced direct cyclobutane pyrimidine dimers (CPD) by ~80% and oxidative DNA damage (8‐OHdG) by ~65% compared with control transfected cells. Similarly, in untransfected cells, the CaSR negative modulator, NPS‐2143 (500 nm), reduced UV‐induced CPD and 8‐OHdG by ~70%. NPS‐2143 also enhanced DNA repair and reduced reactive oxygen species (ROS) by ~35% in UV‐exposed keratinocytes, consistent with reduced DNA damage after UV exposure. Topical application of NPS‐2143 also protected hairless Skh:hr1 mice from UV‐induced CPD, oxidative DNA damage and inflammation, similar to the reductions observed in response to the well‐known photoprotection agent 1,25(OH)2D3 (calcitriol). Thus, negative modulators of the CaSR offer a new approach to reducing UV‐induced skin damage.
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Affiliation(s)
- Chen Yang
- Department of Physiology and Bosch Institute, School of Medical Sciences, University of Sydney, New South Wales, 2006, Australia
| | - Mark Stephen Rybchyn
- School of Chemical Engineering, University of New South Wales, Sydney, NSW, 2033, Australia
| | | | - Jim Matthews
- Sydney Informatics Hub, University of Sydney, New South Wales, Australia
| | - Andrew J A Holland
- Douglas Cohen Department of Paediatric Surgery, The University of Sydney School of Medicine, The Children's Hospital at Westmead Clinical School, Faculty of Medicine and Health, Sydney, New South Wales, Australia
| | - Arthur David Conigrave
- School of Life and Environmental Sciences, Charles Perkins Centre (D17), University of Sydney, New South Wales, 2006, Australia
| | - Rebecca Sara Mason
- Department of Physiology and Bosch Institute, School of Medical Sciences, University of Sydney, New South Wales, 2006, Australia.,School of Life and Environmental Sciences, Charles Perkins Centre (D17), University of Sydney, New South Wales, 2006, Australia
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4
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Wen T, Wang Z, Chen X, Ren Y, Lu X, Xing Y, Lu J, Chang S, Zhang X, Shen Y, Yang X. Structural basis for activation and allosteric modulation of full-length calcium-sensing receptor. SCIENCE ADVANCES 2021; 7:7/23/eabg1483. [PMID: 34088669 PMCID: PMC8177707 DOI: 10.1126/sciadv.abg1483] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 04/19/2021] [Indexed: 06/12/2023]
Abstract
Calcium-sensing receptor (CaSR) is a class C G protein-coupled receptor (GPCR) that plays an important role in calcium homeostasis and parathyroid hormone secretion. Here, we present multiple cryo-electron microscopy structures of full-length CaSR in distinct ligand-bound states. Ligands (Ca2+ and l-tryptophan) bind to the extracellular domain of CaSR and induce large-scale conformational changes, leading to the closure of two heptahelical transmembrane domains (7TMDs) for activation. The positive modulator (evocalcet) and the negative allosteric modulator (NPS-2143) occupy the similar binding pocket in 7TMD. The binding of NPS-2143 causes a considerable rearrangement of two 7TMDs, forming an inactivated TM6/TM6 interface. Moreover, a total of 305 disease-causing missense mutations of CaSR have been mapped to the structure in the active state, creating hotspot maps of five clinical endocrine disorders. Our results provide a structural framework for understanding the activation, allosteric modulation mechanism, and disease therapy for class C GPCRs.
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Affiliation(s)
- Tianlei Wen
- State Key Laboratory of Medicinal Chemical Biology and College of Life Sciences, Nankai University, Tianjin 300350, China
| | - Ziyu Wang
- State Key Laboratory of Medicinal Chemical Biology and College of Life Sciences, Nankai University, Tianjin 300350, China
| | - Xiaozhe Chen
- State Key Laboratory of Medicinal Chemical Biology and College of Life Sciences, Nankai University, Tianjin 300350, China
| | - Yue Ren
- State Key Laboratory of Medicinal Chemical Biology and College of Life Sciences, Nankai University, Tianjin 300350, China
| | - Xuhang Lu
- State Key Laboratory of Medicinal Chemical Biology and College of Life Sciences, Nankai University, Tianjin 300350, China
| | - Yangfei Xing
- State Key Laboratory of Medical Genomics, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200025, China
| | - Jing Lu
- State Key Laboratory of Medicinal Chemical Biology and College of Life Sciences, Nankai University, Tianjin 300350, China
| | - Shenghai Chang
- Department of Biophysics and Department of Pathology of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Center of Cryo-Electron Microscopy, Zhejiang University School of Medicine, Hangzhou, China
| | - Xing Zhang
- Department of Biophysics and Department of Pathology of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Center of Cryo-Electron Microscopy, Zhejiang University School of Medicine, Hangzhou, China
| | - Yuequan Shen
- State Key Laboratory of Medicinal Chemical Biology and College of Life Sciences, Nankai University, Tianjin 300350, China.
- Synergetic Innovation Center of Chemical Science and Engineering, Tianjin 300071, China
| | - Xue Yang
- State Key Laboratory of Medicinal Chemical Biology and College of Life Sciences, Nankai University, Tianjin 300350, China.
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5
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Tan RSG, Lee CHL, Dimke H, Todd Alexander R. The role of calcium-sensing receptor signaling in regulating transepithelial calcium transport. Exp Biol Med (Maywood) 2021; 246:2407-2419. [PMID: 33926258 DOI: 10.1177/15353702211010415] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The calcium-sensing receptor (CaSR) plays a critical role in sensing extracellular calcium (Ca2+) and signaling to maintain Ca2+ homeostasis. In the parathyroid, the CaSR regulates secretion of parathyroid hormone, which functions to increase extracellular Ca2+ levels. The CaSR is also located in other organs imperative to Ca2+ homeostasis including the kidney and intestine, where it modulates Ca2+ reabsorption and absorption, respectively. In this review, we describe CaSR expression and its function in transepithelial Ca2+ transport in the kidney and intestine. Activation of the CaSR leads to G protein dependent and independent signaling cascades. The known CaSR signal transduction pathways involved in modulating paracellular and transcellular epithelial Ca2+ transport are discussed. Mutations in the CaSR cause a range of diseases that manifest in altered serum Ca2+ levels. Gain-of-function mutations in the CaSR result in autosomal dominant hypocalcemia type 1, while loss-of-function mutations cause familial hypocalciuric hypercalcemia. Additionally, the putative serine protease, FAM111A, is discussed as a potential regulator of the CaSR because mutations in FAM111A cause Kenny Caffey syndrome type 2, gracile bone dysplasia, and osteocraniostenosis, diseases that are characterized by hypocalcemia, hypoparathyroidism, and bony abnormalities, i.e. share phenotypic features of autosomal dominant hypocalcemia. Recent work has helped to elucidate the effect of CaSR signaling cascades on downstream proteins involved in Ca2+ transport across renal and intestinal epithelia; however, much remains to be discovered.
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Affiliation(s)
- Rebecca Siu Ga Tan
- Department of Physiology, University of Alberta, Edmonton T6G 1C9, Canada.,Membrane Protein Disease Research Group, University of Alberta, Edmonton T6G 1C9, Canada
| | | | - Henrik Dimke
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense 5000, Denmark.,Department of Nephrology, Odense University Hospital, Odense 5000, Denmark
| | - R Todd Alexander
- Department of Physiology, University of Alberta, Edmonton T6G 1C9, Canada.,Membrane Protein Disease Research Group, University of Alberta, Edmonton T6G 1C9, Canada.,Department of Pediatrics, University of Alberta, Edmonton T6G 1C9, Canada
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6
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Diao J, DeBono A, Josephs TM, Bourke JE, Capuano B, Gregory KJ, Leach K. Therapeutic Opportunities of Targeting Allosteric Binding Sites on the Calcium-Sensing Receptor. ACS Pharmacol Transl Sci 2021; 4:666-679. [PMID: 33860192 DOI: 10.1021/acsptsci.1c00046] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Indexed: 01/24/2023]
Abstract
The CaSR is a class C G protein-coupled receptor (GPCR) that acts as a multimodal chemosensor to maintain diverse homeostatic functions. The CaSR is a clinical therapeutic target in hyperparathyroidism and has emerged as a putative target in several other diseases. These include hyper- and hypocalcaemia caused either by mutations in the CASR gene or in genes that regulate CaSR signaling and expression, and more recently in asthma. The development of CaSR-targeting drugs is complicated by the fact that the CaSR possesses many different binding sites for endogenous and exogenous agonists and allosteric modulators. Binding sites for endogenous and exogenous ligands are located throughout the large CaSR protein and are interconnected in ways that we do not yet fully understand. This review summarizes our current understanding of CaSR physiology, signaling, and structure and how the many different binding sites of the CaSR may be targeted to treat disease.
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Affiliation(s)
- Jiayin Diao
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia
| | - Aaron DeBono
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia.,Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia
| | - Tracy M Josephs
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia
| | - Jane E Bourke
- Department of Pharmacology, Biomedicine Discovery Institute, Monash University, 9 Ancora Imparo Way, Clayton, Victoria 3800, Australia
| | - Ben Capuano
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia
| | - Karen J Gregory
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia.,Department of Pharmacology, Biomedicine Discovery Institute, Monash University, 9 Ancora Imparo Way, Clayton, Victoria 3800, Australia
| | - Katie Leach
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia.,Department of Pharmacology, Biomedicine Discovery Institute, Monash University, 9 Ancora Imparo Way, Clayton, Victoria 3800, Australia
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7
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Hacisuleyman A, Erkip A, Erman B, Erman B. Synchronous and Asynchronous Response in Dynamically Perturbed Proteins. J Phys Chem B 2021; 125:729-739. [PMID: 33464898 DOI: 10.1021/acs.jpcb.0c08409] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
We present a dynamic perturbation-response model of proteins based on the Gaussian Network Model, where a residue is perturbed periodically, and the dynamic response of other residues is determined. The model shows that periodic perturbation causes a synchronous response in phase with the perturbation and an asynchronous response that is out of phase. The asynchronous component results from the viscous effects of the solvent and other dispersive factors in the system. The model is based on the solution of the Langevin equation in the presence of solvent, noise, and perturbation. We introduce several novel ideas: The concept of storage and loss compliance of the protein and their dependence on structure and frequency; the amount of work lost and the residues that contribute significantly to the lost work; new dynamic correlations that result from perturbation; causality, that is, the response of j when i is perturbed is not equal to the response of i when j is perturbed. As examples, we study two systems, namely, bovine rhodopsin and the class of nanobodies. The general results obtained are (i) synchronous and asynchronous correlations depend strongly on the frequency of perturbation, their magnitude decreases with increasing frequency, (ii) time-delayed mean-squared fluctuations of residues have only synchronous components. Asynchronicity is present only in cross correlations, that is, correlations between different residues, (iii) perturbation of loop residues leads to a large dissipation of work, (iv) correlations satisfy the hypothesis of pre-existing pathways according to which information transfer by perturbation rides on already existing equilibrium correlations in the system, (v) dynamic perturbation can introduce a selective response in the system, where the perturbation of each residue excites different sets of responding residues, and (vi) it is possible to identify nondissipative residues whose perturbation does not lead to dissipation in the protein. Despite its simplicity, the model explains several features of allosteric manipulation.
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Affiliation(s)
- Aysima Hacisuleyman
- Department of Chemical and Biological Engineering, Koc University, Sariyer, Istanbul 34450, Turkey
| | - Albert Erkip
- Faculty of Engineering and Natural Sciences, Sabanci University, Tuzla, Istanbul 34956, Turkey
| | - Batu Erman
- Department of Molecular Biology and Genetics, Bogazici University, Bebek, Istanbul 34342, Turkey
| | - Burak Erman
- Department of Chemical and Biological Engineering, Koc University, Sariyer, Istanbul 34450, Turkey
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8
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Ahmad R, Dalziel JE. G Protein-Coupled Receptors in Taste Physiology and Pharmacology. Front Pharmacol 2020; 11:587664. [PMID: 33390961 PMCID: PMC7774309 DOI: 10.3389/fphar.2020.587664] [Citation(s) in RCA: 87] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 10/09/2020] [Indexed: 12/14/2022] Open
Abstract
Heterotrimeric G protein-coupled receptors (GPCRs) comprise the largest receptor family in mammals and are responsible for the regulation of most physiological functions. Besides mediating the sensory modalities of olfaction and vision, GPCRs also transduce signals for three basic taste qualities of sweet, umami (savory taste), and bitter, as well as the flavor sensation kokumi. Taste GPCRs reside in specialised taste receptor cells (TRCs) within taste buds. Type I taste GPCRs (TAS1R) form heterodimeric complexes that function as sweet (TAS1R2/TAS1R3) or umami (TAS1R1/TAS1R3) taste receptors, whereas Type II are monomeric bitter taste receptors or kokumi/calcium-sensing receptors. Sweet, umami and kokumi receptors share structural similarities in containing multiple agonist binding sites with pronounced selectivity while most bitter receptors contain a single binding site that is broadly tuned to a diverse array of bitter ligands in a non-selective manner. Tastant binding to the receptor activates downstream secondary messenger pathways leading to depolarization and increased intracellular calcium in TRCs, that in turn innervate the gustatory cortex in the brain. Despite recent advances in our understanding of the relationship between agonist binding and the conformational changes required for receptor activation, several major challenges and questions remain in taste GPCR biology that are discussed in the present review. In recent years, intensive integrative approaches combining heterologous expression, mutagenesis and homology modeling have together provided insight regarding agonist binding site locations and molecular mechanisms of orthosteric and allosteric modulation. In addition, studies based on transgenic mice, utilizing either global or conditional knock out strategies have provided insights to taste receptor signal transduction mechanisms and their roles in physiology. However, the need for more functional studies in a physiological context is apparent and would be enhanced by a crystallized structure of taste receptors for a more complete picture of their pharmacological mechanisms.
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Affiliation(s)
- Raise Ahmad
- Food Nutrition and Health Team, Food and Bio-based Products Group, AgResearch, Palmerston North, New Zealand
| | - Julie E Dalziel
- Food Nutrition and Health Team, Food and Bio-based Products Group, AgResearch, Palmerston North, New Zealand
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9
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Leach K, Hannan FM, Josephs TM, Keller AN, Møller TC, Ward DT, Kallay E, Mason RS, Thakker RV, Riccardi D, Conigrave AD, Bräuner-Osborne H. International Union of Basic and Clinical Pharmacology. CVIII. Calcium-Sensing Receptor Nomenclature, Pharmacology, and Function. Pharmacol Rev 2020; 72:558-604. [PMID: 32467152 PMCID: PMC7116503 DOI: 10.1124/pr.119.018531] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The calcium-sensing receptor (CaSR) is a class C G protein-coupled receptor that responds to multiple endogenous agonists and allosteric modulators, including divalent and trivalent cations, L-amino acids, γ-glutamyl peptides, polyamines, polycationic peptides, and protons. The CaSR plays a critical role in extracellular calcium (Ca2+ o) homeostasis, as demonstrated by the many naturally occurring mutations in the CaSR or its signaling partners that cause Ca2+ o homeostasis disorders. However, CaSR tissue expression in mammals is broad and includes tissues unrelated to Ca2+ o homeostasis, in which it, for example, regulates the secretion of digestive hormones, airway constriction, cardiovascular effects, cellular differentiation, and proliferation. Thus, although the CaSR is targeted clinically by the positive allosteric modulators (PAMs) cinacalcet, evocalcet, and etelcalcetide in hyperparathyroidism, it is also a putative therapeutic target in diabetes, asthma, cardiovascular disease, and cancer. The CaSR is somewhat unique in possessing multiple ligand binding sites, including at least five putative sites for the "orthosteric" agonist Ca2+ o, an allosteric site for endogenous L-amino acids, two further allosteric sites for small molecules and the peptide PAM, etelcalcetide, and additional sites for other cations and anions. The CaSR is promiscuous in its G protein-coupling preferences, and signals via Gq/11, Gi/o, potentially G12/13, and even Gs in some cell types. Not surprisingly, the CaSR is subject to biased agonism, in which distinct ligands preferentially stimulate a subset of the CaSR's possible signaling responses, to the exclusion of others. The CaSR thus serves as a model receptor to study natural bias and allostery. SIGNIFICANCE STATEMENT: The calcium-sensing receptor (CaSR) is a complex G protein-coupled receptor that possesses multiple orthosteric and allosteric binding sites, is subject to biased signaling via several different G proteins, and has numerous (patho)physiological roles. Understanding the complexities of CaSR structure, function, and biology will aid future drug discovery efforts seeking to target this receptor for a diversity of diseases. This review summarizes what is known to date regarding key structural, pharmacological, and physiological features of the CaSR.
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Affiliation(s)
- Katie Leach
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Fadil M Hannan
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Tracy M Josephs
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Andrew N Keller
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Thor C Møller
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Donald T Ward
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Enikö Kallay
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Rebecca S Mason
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Rajesh V Thakker
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Daniela Riccardi
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Arthur D Conigrave
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Hans Bräuner-Osborne
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
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10
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Josephs TM, Keller AN, Khajehali E, DeBono A, Langmead CJ, Conigrave AD, Capuano B, Kufareva I, Gregory KJ, Leach K. Negative allosteric modulators of the human calcium-sensing receptor bind to overlapping and distinct sites within the 7-transmembrane domain. Br J Pharmacol 2020; 177:1917-1930. [PMID: 31881094 PMCID: PMC7070164 DOI: 10.1111/bph.14961] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2019] [Revised: 12/06/2019] [Accepted: 12/09/2019] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND AND PURPOSE Negative allosteric modulators (NAMs) that target the calcium-sensing receptor (CaS receptor) were originally developed for the treatment of osteoporosis by stimulating the release of endogenous parathyroid hormone, but failed in human clinical trials. Several chemically and structurally distinct NAM scaffolds have been described, but it is not known how these different scaffolds interact with the CaS receptor to inhibit receptor signalling in response to agonists. EXPERIMENTAL APPROACH In the present study, we used a mutagenesis approach combined with analytical pharmacology and computational modelling to probe the binding sites of four distinct NAM scaffolds. KEY RESULTS Although all four scaffolds bind to the 7-transmembrane and/or extracellular or intracellular loops, they occupy distinct regions, as previously shown for positive allosteric modulators of the CaS receptor. Furthermore, different NAM scaffolds mediate negative allosteric modulation via distinct amino acid networks. CONCLUSION AND IMPLICATIONS These findings aid our understanding of how different NAMs bind to and inhibit the CaS receptor. Elucidation of allosteric binding sites in the CaS receptor has implications for the discovery of novel allosteric modulators.
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Affiliation(s)
- Tracy M. Josephs
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical SciencesMonash UniversityParkvilleVICAustralia
| | - Andrew N. Keller
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical SciencesMonash UniversityParkvilleVICAustralia
| | - Elham Khajehali
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical SciencesMonash UniversityParkvilleVICAustralia
| | - Aaron DeBono
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical SciencesMonash UniversityParkvilleVICAustralia
| | - Christopher J. Langmead
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical SciencesMonash UniversityParkvilleVICAustralia
| | - Arthur D. Conigrave
- School of Life and Environmental SciencesUniversity of SydneySydneyNSWAustralia
| | - Ben Capuano
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical SciencesMonash UniversityParkvilleVICAustralia
| | - Irina Kufareva
- Skaggs School of Pharmacy & Pharmaceutical SciencesUniversity of CaliforniaSan DiegoCAUSA
| | - Karen J. Gregory
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical SciencesMonash UniversityParkvilleVICAustralia
| | - Katie Leach
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical SciencesMonash UniversityParkvilleVICAustralia
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11
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Dal Prà I, Armato U, Chiarini A. Family C G-Protein-Coupled Receptors in Alzheimer's Disease and Therapeutic Implications. Front Pharmacol 2019; 10:1282. [PMID: 31719824 PMCID: PMC6826475 DOI: 10.3389/fphar.2019.01282] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 10/07/2019] [Indexed: 12/12/2022] Open
Abstract
Alzheimer’s disease (AD), particularly its sporadic or late-onset form (SAD/LOAD), is the most prevalent (96–98% of cases) neurodegenerative dementia in aged people. AD’s neuropathology hallmarks are intrabrain accumulation of amyloid-β peptides (Aβs) and of hyperphosphorylated Tau (p-Tau) proteins, diffuse neuroinflammation, and progressive death of neurons and oligodendrocytes. Mounting evidences suggest that family C G-protein-coupled receptors (GPCRs), which include γ-aminobutyric acid B receptors (GABABRs), metabotropic glutamate receptors (mGluR1-8), and the calcium-sensing receptor (CaSR), are involved in many neurotransmitter systems that dysfunction in AD. This review updates the available knowledge about the roles of GPCRs, particularly but not exclusively those expressed by brain astrocytes, in SAD/LOAD onset and progression, taking stock of their respective mechanisms of action and of their potential as anti-AD therapeutic targets. In particular, GABABRs prevent Aβs synthesis and neuronal hyperexcitability and group I mGluRs play important pathogenetic roles in transgenic AD-model animals. Moreover, the specific binding of Aβs to the CaSRs of human cortical astrocytes and neurons cultured in vitro engenders a pathological signaling that crucially promotes the surplus synthesis and release of Aβs and hyperphosphorylated Tau proteins, and also of nitric oxide, vascular endothelial growth factor-A, and proinflammatory agents. Concurrently, Aβs•CaSR signaling hinders the release of soluble (s)APP-α peptide, a neurotrophic agent and GABABR1a agonist. Altogether these effects progressively kill human cortical neurons in vitro and likely also in vivo. Several CaSR’s negative allosteric modulators suppress all the noxious effects elicited by Aβs•CaSR signaling in human cortical astrocytes and neurons thus safeguarding neurons’ viability in vitro and raising hopes about their potential therapeutic benefits in AD patients. Further basic and clinical investigations on these hot topics are needed taking always heed that activation of the several brain family C GPCRs may elicit divergent upshots according to the models studied.
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Affiliation(s)
- Ilaria Dal Prà
- Human Histology and Embryology Unit, University of Verona Medical School, Verona, Italy
| | - Ubaldo Armato
- Human Histology and Embryology Unit, University of Verona Medical School, Verona, Italy
| | - Anna Chiarini
- Human Histology and Embryology Unit, University of Verona Medical School, Verona, Italy
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12
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Zhao X, Schindell B, Li W, Ni L, Liu S, Wijerathne CUB, Gong J, Nyachoti CM, O K, Yang C. Distribution and localization of porcine calcium sensing receptor in different tissues of weaned piglets1. J Anim Sci 2019; 97:2402-2413. [PMID: 30887022 PMCID: PMC6541828 DOI: 10.1093/jas/skz096] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 03/18/2019] [Indexed: 02/06/2023] Open
Abstract
Taste receptors including calcium sensing receptor (CaSR) are expressed in various animal tissues, and CaSR plays important roles in nutrient sensing and the physiology, growth, and development of animals. However, molecular distribution of porcine CaSR (pCaSR) in different tissues, especially along the longitudinal axis of the digestive tract in weaned piglets, is still unknown. In the present study, we investigated the distribution and localization of pCaSR in the different tissues including intestinal segments of weaned piglets. Six male pigs were anesthetized and euthanized. Different tissues such as intestinal segments were collected. The pCaSR mRNA abundance, protein abundance, and localization were measured by real-time PCR, Western blotting, and immunohistochemistry, respectively. The mRNA and protein of pCaSR were detected in the kidney, lung, liver, stomach, duodenum, jejunum, ileum, and colon. The pCaSR mRNA was much higher (five to 180 times) in the kidney when compared with other tissues (P < 0.05). The ileum had higher pCaSR mRNA and protein abundances than the stomach, duodenum, jejunum, and colon (P < 0.05). Immunohistochemical staining results indicated that the pCaSR protein was mostly located in the epithelia of the stomach, duodenum, jejunum, ileum, and colon. These results demonstrate that pCaSR is widely expressed in different tissues including intestinal segments in weaned piglets and the ileum has a higher expression level of pCaSR. Further research is needed to confirm the expression of CaSR in the different types of epithelial cells isolated from weaned piglets and characterize the functions of pCaSR, its potential ligands and cell signaling pathways related to CaSR activation in enteroendocrine cells and potentially in enterocytes.
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Affiliation(s)
- Xiaoya Zhao
- Department of Animal Science, University of Manitoba, Winnipeg, MB, Canada
| | - Brayden Schindell
- Department of Animal Science, University of Manitoba, Winnipeg, MB, Canada
| | - Weiqi Li
- Department of Animal Science, University of Manitoba, Winnipeg, MB, Canada
| | - Liju Ni
- Department of Animal Science, University of Manitoba, Winnipeg, MB, Canada
- Shanghai Lab-Animal Research Center, Shanghai, China
| | - Shangxi Liu
- Department of Animal Science, University of Manitoba, Winnipeg, MB, Canada
| | - Charith U B Wijerathne
- Department of Animal Science, University of Manitoba, Winnipeg, MB, Canada
- CCARM, St. Boniface Hospital Research Centre, Winnipeg, MB, Canada
| | - Joshua Gong
- Guelph Research and Development Centre, Agriculture Agri-Food Canada, Guelph, ON, Canada
| | - C Martin Nyachoti
- Department of Animal Science, University of Manitoba, Winnipeg, MB, Canada
| | - Karmin O
- Department of Animal Science, University of Manitoba, Winnipeg, MB, Canada
- CCARM, St. Boniface Hospital Research Centre, Winnipeg, MB, Canada
| | - Chengbo Yang
- Department of Animal Science, University of Manitoba, Winnipeg, MB, Canada
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13
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Gregory K, Kufareva I, Keller AN, Khajehali E, Mun HC, Goolam MA, Mason RS, Capuano B, Conigrave AD, Christopoulos A, Leach K. Dual Action Calcium-Sensing Receptor Modulator Unmasks Novel Mode-Switching Mechanism. ACS Pharmacol Transl Sci 2018; 1:96-109. [PMID: 32219206 PMCID: PMC7089027 DOI: 10.1021/acsptsci.8b00021] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Indexed: 12/17/2022]
Abstract
Negative allosteric modulators (NAMs) of the human calcium-sensing receptor (CaSR) have previously failed to show efficacy in human osteoporosis clinical trials, but there is now significant interest in repurposing these drugs for hypocalcemic disorders and inflammatory lung diseases. However, little is known about how CaSR NAMs inhibit the response to endogenous activators. An improved understanding of CaSR negative allosteric modulation may afford the opportunity to develop therapeutically superior CaSR-targeting drugs. In an attempt to elucidate the mechanistic and structural basis of allosteric modulation mediated by the previously reported NAM, calhex231, we herein demonstrate that calhex231 actually potentiates or inhibits the activity of multiple CaSR agonists depending on whether it occupies one or both protomers in a CaSR dimer. These findings reveal a novel mechanism of mode-switching at a Class C G protein-coupled receptor that has implications for drug discovery and potential clinical utility.
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Affiliation(s)
- Karen
J. Gregory
- Drug
Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, 381 Royal Parade, Monash University, Parkville, Victoria 3052, Australia
| | - Irina Kufareva
- Skaggs
School of Pharmacy & Pharmaceutical Sciences, University of California, 9500 Gilman Drive, La Jolla, San Diego, California MC 0747, United States
| | - Andrew N. Keller
- Drug
Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, 381 Royal Parade, Monash University, Parkville, Victoria 3052, Australia
| | - Elham Khajehali
- Drug
Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, 381 Royal Parade, Monash University, Parkville, Victoria 3052, Australia
| | - Hee-Chang Mun
- School of Life and Environmental
Sciences, Charles Perkins Centre, and Physiology and
Bosch Institute, Building F13, University
of Sydney, Sidney, New South Wales 2006, Australia
| | - Mahvash A. Goolam
- School of Life and Environmental
Sciences, Charles Perkins Centre, and Physiology and
Bosch Institute, Building F13, University
of Sydney, Sidney, New South Wales 2006, Australia
| | - Rebecca S. Mason
- School of Life and Environmental
Sciences, Charles Perkins Centre, and Physiology and
Bosch Institute, Building F13, University
of Sydney, Sidney, New South Wales 2006, Australia
| | - Ben Capuano
- Drug
Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, 381 Royal Parade, Monash University, Parkville, Victoria 3052, Australia
| | - Arthur D. Conigrave
- School of Life and Environmental
Sciences, Charles Perkins Centre, and Physiology and
Bosch Institute, Building F13, University
of Sydney, Sidney, New South Wales 2006, Australia
| | - Arthur Christopoulos
- Drug
Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, 381 Royal Parade, Monash University, Parkville, Victoria 3052, Australia
| | - Katie Leach
- Drug
Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, 381 Royal Parade, Monash University, Parkville, Victoria 3052, Australia
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14
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Hannan FM, Olesen MK, Thakker RV. Calcimimetic and calcilytic therapies for inherited disorders of the calcium-sensing receptor signalling pathway. Br J Pharmacol 2018; 175:4083-4094. [PMID: 29127708 PMCID: PMC6177618 DOI: 10.1111/bph.14086] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 10/24/2017] [Accepted: 10/30/2017] [Indexed: 12/15/2022] Open
Abstract
The calcium-sensing receptor (CaS receptor) plays a pivotal role in extracellular calcium homeostasis, and germline loss-of-function and gain-of-function mutations cause familial hypocalciuric hypercalcaemia (FHH) and autosomal dominant hypocalcaemia (ADH), respectively. CaS receptor signal transduction in the parathyroid glands is probably regulated by G-protein subunit α11 (Gα11 ) and adaptor-related protein complex-2 σ-subunit (AP2σ), and recent studies have identified germline mutations of these proteins as a cause of FHH and/or ADH. Calcimimetics and calcilytics are positive and negative allosteric modulators of the CaS receptor that have potential efficacy for symptomatic forms of FHH and ADH. Cellular studies have demonstrated that these compounds correct signalling and/or trafficking defects caused by mutant CaS receptor, Gα11 or AP2σ proteins. Moreover, mouse model studies indicate that calcilytics can rectify the hypocalcaemia and hypercalciuria associated with ADH, and patient-based studies reveal calcimimetics to ameliorate symptomatic hypercalcaemia caused by FHH. Thus, calcimimetics and calcilytics represent targeted therapies for inherited disorders of the CaS receptor signalling pathway. LINKED ARTICLES This article is part of a themed section on Molecular Pharmacology of GPCRs. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.21/issuetoc.
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Affiliation(s)
- Fadil M Hannan
- Department of Musculoskeletal Biology, Institute of Ageing and Chronic DiseaseUniversity of LiverpoolLiverpoolUK
- Academic Endocrine Unit, Radcliffe Department of MedicineUniversity of OxfordOxfordUK
| | - Mie K Olesen
- Department of Musculoskeletal Biology, Institute of Ageing and Chronic DiseaseUniversity of LiverpoolLiverpoolUK
- Academic Endocrine Unit, Radcliffe Department of MedicineUniversity of OxfordOxfordUK
| | - Rajesh V Thakker
- Academic Endocrine Unit, Radcliffe Department of MedicineUniversity of OxfordOxfordUK
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15
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Gorvin CM. Insights into calcium-sensing receptor trafficking and biased signalling by studies of calcium homeostasis. J Mol Endocrinol 2018; 61:R1-R12. [PMID: 29599414 DOI: 10.1530/jme-18-0049] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 03/29/2018] [Indexed: 12/18/2022]
Abstract
The calcium-sensing receptor (CASR) is a class C G-protein-coupled receptor (GPCR) that detects extracellular calcium concentrations, and modulates parathyroid hormone secretion and urinary calcium excretion to maintain calcium homeostasis. The CASR utilises multiple heterotrimeric G-proteins to mediate signalling effects including activation of intracellular calcium release; mitogen-activated protein kinase (MAPK) pathways; membrane ruffling; and inhibition of cAMP production. By studying germline mutations in the CASR and proteins within its signalling pathway that cause hyper- and hypocalcaemic disorders, novel mechanisms governing GPCR signalling and trafficking have been elucidated. This review focusses on two recently described pathways that provide novel insights into CASR signalling and trafficking mechanisms. The first, identified by studying a CASR gain-of-function mutation that causes autosomal dominant hypocalcaemia (ADH), demonstrated a structural motif located between the third transmembrane domain and the second extracellular loop of the CASR that mediates biased signalling by activating a novel β-arrestin-mediated G-protein-independent pathway. The second, in which the mechanism by which adaptor protein-2 σ-subunit (AP2σ) mutations cause familial hypocalciuric hypercalcaemia (FHH) was investigated, demonstrated that AP2σ mutations impair CASR internalisation and reduce multiple CASR-mediated signalling pathways. Furthermore, these studies showed that the CASR can signal from the cell surface using multiple G-protein pathways, whilst sustained signalling is mediated only by the Gq/11 pathway. Thus, studies of FHH- and ADH-associated mutations have revealed novel steps by which CASR mediates signalling and compartmental bias, and these pathways could provide new targets for therapies for patients with calcaemic disorders.
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Affiliation(s)
- Caroline M Gorvin
- Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Birmingham, UK
- Centre for Endocrinology, Diabetes and Metabolism (CEDAM), Birmingham Health Partners, Birmingham, UK
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16
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Keller AN, Kufareva I, Josephs TM, Diao J, Mai VT, Conigrave AD, Christopoulos A, Gregory KJ, Leach K. Identification of Global and Ligand-Specific Calcium Sensing Receptor Activation Mechanisms. Mol Pharmacol 2018; 93:619-630. [PMID: 29636377 DOI: 10.1124/mol.118.112086] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 04/06/2018] [Indexed: 12/11/2022] Open
Abstract
Calcium sensing receptor (CaSR) positive allosteric modulators (PAMs) are therapeutically important. However, few are approved for clinical use, in part due to complexities in assessing allostery at a receptor where the endogenous agonist (extracellular calcium) is present in all biologic fluids. Such complexity impedes efforts to quantify and optimize allosteric drug parameters (affinity, cooperativity, and efficacy) that dictate PAM structure-activity relationships (SARs). Furthermore, an underappreciation of the structural mechanisms underlying CaSR activation hinders predictions of how PAM SAR relates to in vitro and in vivo activity. Herein, we combined site-directed mutagenesis and calcium mobilization assays with analytical pharmacology to compare modes of PAM binding, positive modulation, and agonism. We demonstrate that 3-(2-chlorophenyl)-N-((1R)-1-(3-methoxyphenyl)ethyl)-1-propanamine (NPS R568) binds to a 7 transmembrane domain (7TM) cavity common to class C G protein-coupled receptors and used by (αR)-(-)-α-methyl-N-[3-[3-[trifluoromethylphenyl]propyl]-1-napthalenemethanamine (cinacalcet) and 1-benzothiazol-2-yl-1-(2,4-dimethylphenyl)-ethanol (AC265347); however, there are subtle distinctions in the contribution of select residues to the binding and transmission of cooperativity by PAMs. Furthermore, we reveal some common activation mechanisms used by different CaSR activators, but also demonstrate some differential contributions of residues within the 7TM bundle and extracellular loops to the efficacy of the PAM-agonist, AC265347, versus cooperativity. Finally, we show that PAMS potentiate the affinity of divalent cations. Our results support the existence of both global and ligand-specific CaSR activation mechanisms and reveal that allosteric agonism is mediated in part via distinct mechanisms to positive modulation.
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Affiliation(s)
- Andrew N Keller
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia (A.N.K., T.M.J., J.D., V.T.M., A.C., K.J.G., K.L.); Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, La Jolla, San Diego, California (I.K.); and School of Life and Environmental Sciences, Charles Perkins Centre (D17), University of Sydney, New South Wales, Australia (A.D.C.)
| | - Irina Kufareva
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia (A.N.K., T.M.J., J.D., V.T.M., A.C., K.J.G., K.L.); Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, La Jolla, San Diego, California (I.K.); and School of Life and Environmental Sciences, Charles Perkins Centre (D17), University of Sydney, New South Wales, Australia (A.D.C.)
| | - Tracy M Josephs
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia (A.N.K., T.M.J., J.D., V.T.M., A.C., K.J.G., K.L.); Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, La Jolla, San Diego, California (I.K.); and School of Life and Environmental Sciences, Charles Perkins Centre (D17), University of Sydney, New South Wales, Australia (A.D.C.)
| | - Jiayin Diao
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia (A.N.K., T.M.J., J.D., V.T.M., A.C., K.J.G., K.L.); Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, La Jolla, San Diego, California (I.K.); and School of Life and Environmental Sciences, Charles Perkins Centre (D17), University of Sydney, New South Wales, Australia (A.D.C.)
| | - Vyvyan T Mai
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia (A.N.K., T.M.J., J.D., V.T.M., A.C., K.J.G., K.L.); Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, La Jolla, San Diego, California (I.K.); and School of Life and Environmental Sciences, Charles Perkins Centre (D17), University of Sydney, New South Wales, Australia (A.D.C.)
| | - Arthur D Conigrave
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia (A.N.K., T.M.J., J.D., V.T.M., A.C., K.J.G., K.L.); Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, La Jolla, San Diego, California (I.K.); and School of Life and Environmental Sciences, Charles Perkins Centre (D17), University of Sydney, New South Wales, Australia (A.D.C.)
| | - Arthur Christopoulos
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia (A.N.K., T.M.J., J.D., V.T.M., A.C., K.J.G., K.L.); Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, La Jolla, San Diego, California (I.K.); and School of Life and Environmental Sciences, Charles Perkins Centre (D17), University of Sydney, New South Wales, Australia (A.D.C.)
| | - Karen J Gregory
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia (A.N.K., T.M.J., J.D., V.T.M., A.C., K.J.G., K.L.); Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, La Jolla, San Diego, California (I.K.); and School of Life and Environmental Sciences, Charles Perkins Centre (D17), University of Sydney, New South Wales, Australia (A.D.C.)
| | - Katie Leach
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia (A.N.K., T.M.J., J.D., V.T.M., A.C., K.J.G., K.L.); Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, La Jolla, San Diego, California (I.K.); and School of Life and Environmental Sciences, Charles Perkins Centre (D17), University of Sydney, New South Wales, Australia (A.D.C.)
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17
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Nemeth EF, Van Wagenen BC, Balandrin MF. Discovery and Development of Calcimimetic and Calcilytic Compounds. PROGRESS IN MEDICINAL CHEMISTRY 2018; 57:1-86. [PMID: 29680147 DOI: 10.1016/bs.pmch.2017.12.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The extracellular calcium receptor (CaR) is a G protein-coupled receptor (GPCR) and the pivotal molecule regulating systemic Ca2+ homeostasis. The CaR was a challenging target for drug discovery because its physiological ligand is an inorganic ion (Ca2+) rather than a molecule so there was no structural template to guide medicinal chemistry. Nonetheless, small molecules targeting this receptor were discovered. Calcimimetics are agonists or positive allosteric modulators of the CaR, while calcilytics are antagonists and all to date are negative allosteric modulators. The calcimimetic cinacalcet was the first allosteric modulator of a GPCR to achieve regulatory approval and is a first-in-class treatment for secondary hyperparathyroidism in patients on dialysis, and for hypercalcemia in some forms of primary hyperparathyroidism. It is also useful in treating some rare genetic diseases that cause hypercalcemia. Two other calcimimetics are now on the market (etelcalcetide) or under regulatory review (evocalcet). Calcilytics stimulate the secretion of parathyroid hormone and were initially developed as treatments for osteoporosis. Three different calcilytics of two different chemotypes failed in clinical trials due to lack of efficacy. Calcilytics are now being repurposed and might be useful in treating hypoparathyroidism and several rare genetic diseases causing hypocalcemia. The challenges ahead for medicinal chemists are to design compounds that select conformations of the CaR that preferentially target a particular signalling pathway and/or that affect the CaR in a tissue-selective manner.
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18
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Gorvin CM, Babinsky VN, Malinauskas T, Nissen PH, Schou AJ, Hanyaloglu AC, Siebold C, Jones EY, Hannan FM, Thakker RV. A calcium-sensing receptor mutation causing hypocalcemia disrupts a transmembrane salt bridge to activate β-arrestin-biased signaling. Sci Signal 2018; 11:eaan3714. [PMID: 29463778 PMCID: PMC6166785 DOI: 10.1126/scisignal.aan3714] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The calcium-sensing receptor (CaSR) is a G protein-coupled receptor (GPCR) that signals through Gq/11 and Gi/o to stimulate cytosolic calcium (Ca2+i) and mitogen-activated protein kinase (MAPK) signaling to control extracellular calcium homeostasis. Studies of loss- and gain-of-function CASR mutations, which cause familial hypocalciuric hypercalcemia type 1 (FHH1) and autosomal dominant hypocalcemia type 1 (ADH1), respectively, have revealed that the CaSR signals in a biased manner. Thus, some mutations associated with FHH1 lead to signaling predominantly through the MAPK pathway, whereas mutations associated with ADH1 preferentially enhance Ca2+i responses. We report a previously unidentified ADH1-associated R680G CaSR mutation, which led to the identification of a CaSR structural motif that mediates biased signaling. Expressing CaSRR680G in HEK 293 cells showed that this mutation increased MAPK signaling without altering Ca2+i responses. Moreover, this gain of function in MAPK activity occurred independently of Gq/11 and Gi/o and was mediated instead by a noncanonical pathway involving β-arrestin proteins. Homology modeling and mutagenesis studies showed that the R680G CaSR mutation selectively enhanced β-arrestin signaling by disrupting a salt bridge formed between Arg680 and Glu767, which are located in CaSR transmembrane domain 3 and extracellular loop 2, respectively. Thus, our results demonstrate CaSR signaling through β-arrestin and the importance of the Arg680-Glu767 salt bridge in mediating signaling bias.
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Affiliation(s)
- Caroline M Gorvin
- Academic Endocrine Unit, Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 7LJ, UK
| | - Valerie N Babinsky
- Academic Endocrine Unit, Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 7LJ, UK
| | - Tomas Malinauskas
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Peter H Nissen
- Department of Clinical Biochemistry, Aarhus University Hospital, DK-8200 Aarhus N, Denmark
| | - Anders J Schou
- Hans Christian Andersen Children's Hospital, Odense University Hospital, 5000 Odense C, Denmark
| | - Aylin C Hanyaloglu
- Institute of Reproductive and Developmental Biology, Faculty of Medicine, Imperial College London W12 0NN, UK
| | - Christian Siebold
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - E Yvonne Jones
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Fadil M Hannan
- Academic Endocrine Unit, Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 7LJ, UK.
- Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool L7 8TX, UK
| | - Rajesh V Thakker
- Academic Endocrine Unit, Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 7LJ, UK.
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19
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Investigating the molecular mechanism of positive and negative allosteric modulators in the calcium-sensing receptor dimer. Sci Rep 2017; 7:46355. [PMID: 28417952 PMCID: PMC5394417 DOI: 10.1038/srep46355] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 03/20/2017] [Indexed: 11/09/2022] Open
Abstract
Allosteric modulators that are targeting the calcium-sensing receptor (CaSR) hold great therapeutic potential, and elucidating the molecular basis for modulation would thus benefit the development of novel therapeutics. In the present study, we aimed at investigating the mechanism of allosteric modulation in CaSR by testing dimers carrying mutations in the allosteric site of one or both of the subunits. To ensure measurements on a well-defined dimer composition, we applied a trans-activation system in which only the specific heterodimer of two loss-of-function mutants responded to agonist. Although one of these mutants was potentiated by a positive allosteric modulator, we showed that receptor activity was further potentiated in a trans-activation heterodimer containing a single allosteric site, however only when the allosteric site was located in the subunit responsible for G protein coupling. On the contrary, preventing activation in both subunits was necessary for obtaining full inhibition by a negative allosteric modulator. These findings correlate with the proposed activation mechanism of the metabotropic glutamate receptors (mGluRs), in which only a single transmembrane domain is activated at a time. CaSR and mGluRs belong to the class C G protein-coupled receptors, and our findings thus suggest that the activation mechanism is common to this subfamily.
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20
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Mingione A, Verdelli C, Ferrero S, Vaira V, Guarnieri V, Scillitani A, Vicentini L, Balza G, Beretta E, Terranegra A, Vezzoli G, Soldati L, Corbetta S. Filamin A is reduced and contributes to the CASR sensitivity in human parathyroid tumors. J Mol Endocrinol 2017; 58:91-103. [PMID: 27872158 DOI: 10.1530/jme-16-0184] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2016] [Accepted: 11/21/2016] [Indexed: 11/08/2022]
Abstract
Parathyroid tumors display reduced sensitivity to extracellular calcium ([Ca2+]o). [Ca2+]o activates calcium-sensing receptor (CASR), which interacts with the scaffold protein filamin A (FLNA). The study aimed to investigate: (1) the FLNA expression in human parathyroid tumors, (2) its effects on the CASR mRNA and protein expression, and (3) on ERK signaling activation, (4) the effect of the carboxy-terminal CASR variants and (5) of the treatment with the CASR agonist R568 on FLNA-mediated ERK phosphorylation in HEK293 cells. Full-length FLNA immunostaining was variably reduced in parathyroid tumors. Immunofluorescence showed that FLNA localized in membrane and cytoplasm and co-localized with CASR in parathyroid adenomas (PAds)-derived cells. Cleaved C-terminus FLNA fragment could also be detected in PAds nuclear protein fractions. In HEK293 cells transfected with 990R-CASR or 990G-CASR variants, silencing of endogenous FLNA reduced CASR mRNA levels and total and membrane-associated CASR proteins. In agreement, FLNA mRNA levels positively correlated with CASR expression in a series of 74 PAds; however, any significant correlation with primary hyperparathyroidism severity could be detected and FLNA transcript levels did not differ between PAds harboring 990R or 990G CASR variants. R568 treatment was efficient in restoring 990R-CASR and 990G-CASR sensitivity to [Ca2+]o in the absence of FLNA. In conclusion, FLNA is downregulated in parathyroid tumors and parallels the CASR expression levels. Loss of FLNA reduces CASR mRNA and protein expression levels and the CASR-induced ERK phosphorylation. FLNA is involved in receptor expression, membrane localization and ERK signaling activation of both 990R and 990G CASR variants.
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Affiliation(s)
| | - Chiara Verdelli
- Laboratory of Experimental EndocrinologyIRCCS Istituto Ortopedico Galeazzi, Milan, Italy
| | - Stefano Ferrero
- Division of PathologyDepartment of Biomedical, Surgical and Dental Sciences, University of Milan, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Valentina Vaira
- Division of PathologyDepartment of Pathophysiology and Transplantation, University of Milan, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico and Istituto Nazionale Genetica Molecolare (INGM) Romeo ed Enrica Invernizzi, Milan, Italy
| | - Vito Guarnieri
- Medical GeneticsIRCCS Hospital Casa Sollievo della Sofferenza, San Giovanni Rotondo (FG), Italy
| | - Alfredo Scillitani
- Endocrine UnitIRCCS Hospital Casa Sollievo della Sofferenza, San Giovanni Rotondo (FG), Italy
| | - Leonardo Vicentini
- Endocrine SurgeryIRCCS Fondazione Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Gianni Balza
- Internal Medicine UnitA.O. Alessandro Manzoni, Lecco, Italy
| | | | | | - Giuseppe Vezzoli
- Nephrology and Dialysis UnitIRCCS Ospedale San Raffaele, Milan, Italy
| | - Laura Soldati
- Department of Health SciencesUniversity of Milan, Milan, Italy
| | - Sabrina Corbetta
- Endocrinology ServiceDepartment of Biomedical Sciences for Health, University of Milan, IRCCS Istituto Ortopedico Galeazzi, Milan, Italy
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21
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Leach K, Gregory KJ. Molecular insights into allosteric modulation of Class C G protein-coupled receptors. Pharmacol Res 2017; 116:105-118. [DOI: 10.1016/j.phrs.2016.12.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Revised: 11/18/2016] [Accepted: 12/07/2016] [Indexed: 12/23/2022]
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22
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Hernández-Bedolla MA, González-Domínguez E, Zavala-Barrera C, Gutiérrez-López TY, Hidalgo-Moyle JJ, Vázquez-Prado J, Sánchez-Torres C, Reyes-Cruz G. Calcium-sensing-receptor (CaSR) controls IL-6 secretion in metastatic breast cancer MDA-MB-231 cells by a dual mechanism revealed by agonist and inverse-agonist modulators. Mol Cell Endocrinol 2016; 436:159-68. [PMID: 27477783 DOI: 10.1016/j.mce.2016.07.038] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 07/27/2016] [Accepted: 07/27/2016] [Indexed: 01/25/2023]
Abstract
IL-6 is a tightly controlled pleiotropic cytokine with hormone-like properties whose levels are frequently altered in cancer and inflammatory diseases. In highly invasive MDA-MB-231 breast cancer cells, basal activity of endogenously expressed calcium sensing receptor (CaSR) promotes IL-6 secretion. Interestingly, upon agonist stimulation, CaSR reduces IL-6 levels whereas it promotes secretion of various other cytokines and growth factors, raising intriguing questions about how CaSR signaling modulates IL-6 secretion. Here, using NPS-2143, which acted as an inverse agonist, we show that IL-6 secretion promoted by constitutive activity of CaSR is mechanistically linked to Gαs/PKC, MEK1/2 and mTORC1 signaling pathways, integrated by transactivated EGFR. On the other hand, agonist-stimulated CaSR engages in a Rab11a-dependent trafficking pathway critical to inhibit constitutive IL-6 secretion via the PI3K/AKT and PKC signaling pathways. These results support the emerging potential of CaSR as a therapeutic target in metastatic breast cancer whose pharmacological modulation would reduce IL-6.
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Affiliation(s)
- Marco Antonio Hernández-Bedolla
- Department of Cell Biology, Centro de Investigación y Estudios Avanzados del IPN, Apartado postal 14-740, México, D.F., 07360, Mexico
| | - Erika González-Domínguez
- Department of Molecular Biomedicine, Centro de Investigación y Estudios Avanzados del IPN, Apartado postal 14-740, México, D.F., 07360, Mexico
| | - Cesar Zavala-Barrera
- Department of Cell Biology, Centro de Investigación y Estudios Avanzados del IPN, Apartado postal 14-740, México, D.F., 07360, Mexico
| | - Tania Yareli Gutiérrez-López
- Department of Cell Biology, Centro de Investigación y Estudios Avanzados del IPN, Apartado postal 14-740, México, D.F., 07360, Mexico
| | - Joseline Janai Hidalgo-Moyle
- Department of Cell Biology, Centro de Investigación y Estudios Avanzados del IPN, Apartado postal 14-740, México, D.F., 07360, Mexico
| | - José Vázquez-Prado
- Department of Pharmacology, Centro de Investigación y Estudios Avanzados del IPN, Apartado postal 14-740, México, D.F., 07360, Mexico
| | - Carmen Sánchez-Torres
- Department of Molecular Biomedicine, Centro de Investigación y Estudios Avanzados del IPN, Apartado postal 14-740, México, D.F., 07360, Mexico
| | - Guadalupe Reyes-Cruz
- Department of Cell Biology, Centro de Investigación y Estudios Avanzados del IPN, Apartado postal 14-740, México, D.F., 07360, Mexico.
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23
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Zhang C, Miller CL, Gorkhali R, Zou J, Huang K, Brown EM, Yang JJ. Molecular Basis of the Extracellular Ligands Mediated Signaling by the Calcium Sensing Receptor. Front Physiol 2016; 7:441. [PMID: 27746744 PMCID: PMC5043022 DOI: 10.3389/fphys.2016.00441] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Accepted: 09/16/2016] [Indexed: 12/20/2022] Open
Abstract
Ca2+-sensing receptors (CaSRs) play a central role in regulating extracellular calcium concentration ([Ca2+]o) homeostasis and many (patho)physiological processes in multiple organs. This regulation is orchestrated by a cooperative response to extracellular stimuli such as small changes in Ca2+, Mg2+, amino acids, and other ligands. In addition, CaSR is a pleiotropic receptor regulating several intracellular signaling pathways, including calcium mobilization and intracellular calcium oscillation. Nearly 200 mutations and polymorphisms have been found in CaSR in relation to a variety of human disorders associated with abnormal Ca2+ homeostasis. In this review, we summarize efforts directed at identifying binding sites for calcium and amino acids. Both homotropic cooperativity among multiple calcium binding sites and heterotropic cooperativity between calcium and amino acid were revealed using computational modeling, predictions, and site-directed mutagenesis coupled with functional assays. The hinge region of the bilobed Venus flytrap (VFT) domain of CaSR plays a pivotal role in coordinating multiple extracellular stimuli, leading to cooperative responses from the receptor. We further highlight the extensive number of disease-associated mutations that have also been shown to affect CaSR's cooperative action via several types of mechanisms. These results provide insights into the molecular bases of the structure and functional cooperativity of this receptor and other members of family C of the G protein-coupled receptors (cGPCRs) in health and disease states, and may assist in the prospective development of novel receptor-based therapeutics.
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Affiliation(s)
- Chen Zhang
- Department of Chemistry, Georgia State University Atlanta, GA, USA
| | | | - Rakshya Gorkhali
- Department of Chemistry, Georgia State University Atlanta, GA, USA
| | - Juan Zou
- Department of Chemistry, Georgia State University Atlanta, GA, USA
| | - Kenneth Huang
- Department of Chemistry, Georgia State University Atlanta, GA, USA
| | - Edward M Brown
- Center for Diagnostics and Therapeutics, Georgia State UniversityAtlanta, GA, USA; Division of Endocrinology, Diabetes and Hypertension, Department of Medicine, Brigham and Women's HospitalBoston, MA, USA
| | - Jenny J Yang
- Department of Chemistry, Georgia State University Atlanta, GA, USA
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24
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Leach K, Gregory KJ, Kufareva I, Khajehali E, Cook AE, Abagyan R, Conigrave AD, Sexton PM, Christopoulos A. Towards a structural understanding of allosteric drugs at the human calcium-sensing receptor. Cell Res 2016; 26:574-92. [PMID: 27002221 DOI: 10.1038/cr.2016.36] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Revised: 12/18/2015] [Accepted: 01/28/2016] [Indexed: 12/19/2022] Open
Abstract
Drugs that allosterically target the human calcium-sensing receptor (CaSR) have substantial therapeutic potential, but are currently limited. Given the absence of high-resolution structures of the CaSR, we combined mutagenesis with a novel analytical approach and molecular modeling to develop an "enriched" picture of structure-function requirements for interaction between Ca(2+)o and allosteric modulators within the CaSR's 7 transmembrane (7TM) domain. An extended cavity that accommodates multiple binding sites for structurally diverse ligands was identified. Phenylalkylamines bind to a site that overlaps with a putative Ca(2+)o-binding site and extends towards an extracellular vestibule. In contrast, the structurally and pharmacologically distinct AC-265347 binds deeper within the 7TM domains. Furthermore, distinct amino acid networks were found to mediate cooperativity by different modulators. These findings may facilitate the rational design of allosteric modulators with distinct and potentially pathway-biased pharmacological effects.
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Affiliation(s)
- Katie Leach
- Drug Discovery Biology, Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Karen J Gregory
- Drug Discovery Biology, Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Irina Kufareva
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92037, USA
| | - Elham Khajehali
- Drug Discovery Biology, Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Anna E Cook
- Drug Discovery Biology, Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Ruben Abagyan
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92037, USA
| | - Arthur D Conigrave
- School of Molecular Bioscience, Charles Perkins Centre, University of Sydney, NSW 2006, Australia
| | - Patrick M Sexton
- Drug Discovery Biology, Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Arthur Christopoulos
- Drug Discovery Biology, Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
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25
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Babinsky VN, Hannan FM, Gorvin CM, Howles SA, Nesbit MA, Rust N, Hanyaloglu AC, Hu J, Spiegel AM, Thakker RV. Allosteric Modulation of the Calcium-sensing Receptor Rectifies Signaling Abnormalities Associated with G-protein α-11 Mutations Causing Hypercalcemic and Hypocalcemic Disorders. J Biol Chem 2016; 291:10876-85. [PMID: 26994139 PMCID: PMC4865932 DOI: 10.1074/jbc.m115.696401] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2015] [Indexed: 11/06/2022] Open
Abstract
Germline loss- and gain-of-function mutations of G-protein α-11 (Gα11), which couples the calcium-sensing receptor (CaSR) to intracellular calcium (Ca2+i) signaling, lead to familial hypocalciuric hypercalcemia type 2 (FHH2) and autosomal dominant hypocalcemia type 2 (ADH2), respectively, whereas somatic Gα11 mutations mediate uveal melanoma development by constitutively up-regulating MAPK signaling. Cinacalcet and NPS-2143 are allosteric CaSR activators and inactivators, respectively, that ameliorate signaling disturbances associated with CaSR mutations, but their potential to modulate abnormalities of the downstream Gα11 protein is unknown. This study investigated whether cinacalcet and NPS-2143 may rectify Ca2+i alterations associated with FHH2- and ADH2-causing Gα11 mutations, and evaluated the influence of germline gain-of-function Gα11 mutations on MAPK signaling by measuring ERK phosphorylation, and assessed the effect of NPS-2143 on a uveal melanoma Gα11 mutant. WT and mutant Gα11 proteins causing FHH2, ADH2 or uveal melanoma were transfected in CaSR-expressing HEK293 cells, and Ca2+i and ERK phosphorylation responses measured by flow-cytometry and Alphascreen immunoassay following exposure to extracellular Ca2+ (Ca2+o) and allosteric modulators. Cinacalcet and NPS-2143 rectified the Ca2+i responses of FHH2- and ADH2-associated Gα11 loss- and gain-of-function mutations, respectively. ADH2-causing Gα11 mutations were demonstrated not to be constitutively activating and induced ERK phosphorylation following Ca2+o stimulation only. The increased ERK phosphorylation associated with ADH2 and uveal melanoma mutants was rectified by NPS-2143. These findings demonstrate that CaSR-targeted compounds can rectify signaling disturbances caused by germline and somatic Gα11 mutations, which respectively lead to calcium disorders and tumorigenesis; and that ADH2-causing Gα11 mutations induce non-constitutive alterations in MAPK signaling.
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Affiliation(s)
- Valerie N Babinsky
- From the Radcliffe Department of Medicine, University of Oxford, Oxford OX3 7LJ, United Kingdom
| | - Fadil M Hannan
- From the Radcliffe Department of Medicine, University of Oxford, Oxford OX3 7LJ, United Kingdom, Department of Musculoskeletal Biology, University of Liverpool, Liverpool L69 3GA, United Kingdom
| | - Caroline M Gorvin
- From the Radcliffe Department of Medicine, University of Oxford, Oxford OX3 7LJ, United Kingdom
| | - Sarah A Howles
- From the Radcliffe Department of Medicine, University of Oxford, Oxford OX3 7LJ, United Kingdom
| | - M Andrew Nesbit
- From the Radcliffe Department of Medicine, University of Oxford, Oxford OX3 7LJ, United Kingdom, Biomedical Sciences Research Institute, Ulster University, Coleraine BT52 1SA, United Kingdom
| | - Nigel Rust
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, United Kingdom
| | - Aylin C Hanyaloglu
- Department of Surgery and Cancer, Institute of Reproductive Biology and Development, Imperial College London, London W12 0NN, United Kingdom
| | - Jianxin Hu
- Laboratory of Bioorganic Chemistry, NIDDK, National Institutes of Health, Bethesda, Maryland 20892, and
| | | | - Rajesh V Thakker
- From the Radcliffe Department of Medicine, University of Oxford, Oxford OX3 7LJ, United Kingdom,
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26
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Hannan FM, Walls GV, Babinsky VN, Nesbit MA, Kallay E, Hough TA, Fraser WD, Cox RD, Hu J, Spiegel AM, Thakker RV. The Calcilytic Agent NPS 2143 Rectifies Hypocalcemia in a Mouse Model With an Activating Calcium-Sensing Receptor (CaSR) Mutation: Relevance to Autosomal Dominant Hypocalcemia Type 1 (ADH1). Endocrinology 2015; 156:3114-21. [PMID: 26052899 PMCID: PMC4541614 DOI: 10.1210/en.2015-1269] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Autosomal dominant hypocalcemia type 1 (ADH1) is caused by germline gain-of-function mutations of the calcium-sensing receptor (CaSR) and may lead to symptomatic hypocalcemia, inappropriately low serum PTH concentrations and hypercalciuria. Negative allosteric CaSR modulators, known as calcilytics, have been shown to normalize the gain-of-function associated with ADH-causing CaSR mutations in vitro and represent a potential targeted therapy for ADH1. However, the effectiveness of calcilytic drugs for the treatment of ADH1-associated hypocalcemia remains to be established. We have investigated NPS 2143, a calcilytic compound, for the treatment of ADH1 by in vitro and in vivo studies involving a mouse model, known as Nuf, which harbors a gain-of-function CaSR mutation, Leu723Gln. Wild-type (Leu723) and Nuf mutant (Gln723) CaSRs were expressed in HEK293 cells, and the effect of NPS 2143 on their intracellular calcium responses was determined by flow cytometry. NPS 2143 was also administered as a single ip bolus to wild-type and Nuf mice and plasma concentrations of calcium and PTH, and urinary calcium excretion measured. In vitro administration of NPS 2143 decreased the intracellular calcium responses of HEK293 cells expressing the mutant Gln723 CaSR in a dose-dependent manner, thereby rectifying the gain-of-function associated with the Nuf mouse CaSR mutation. Intraperitoneal injection of NPS 2143 in Nuf mice led to significant increases in plasma calcium and PTH without elevating urinary calcium excretion. These studies of a mouse model with an activating CaSR mutation demonstrate NPS 2143 to normalize the gain-of-function causing ADH1 and improve the hypocalcemia associated with this disorder.
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Affiliation(s)
- Fadil M Hannan
- Academic Endocrine Unit (F.M.H., G.V.W., V.N.B., M.A.N., E.K., R.V.T.), Radcliffe Department of Medicine, Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, OX3 7LJ, United Kingdom; Medical Research Council (MRC) Mammalian Genetics Unit and Mary Lyon Centre (T.A.H., R.D.C.), MRC Harwell, Harwell Science and Innovation Campus, Oxfordshire, OX11 0RD, United Kingdom; Department of Medicine (W.D.F.), Norwich Medical School, University of East Anglia, Norwich, NR4 7TJ, United Kingdom; Laboratory of Bioorganic Chemistry (J.H.), National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892; and Albert Einstein College of Medicine (A.M.S.), Bronx, New York 10461
| | - Gerard V Walls
- Academic Endocrine Unit (F.M.H., G.V.W., V.N.B., M.A.N., E.K., R.V.T.), Radcliffe Department of Medicine, Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, OX3 7LJ, United Kingdom; Medical Research Council (MRC) Mammalian Genetics Unit and Mary Lyon Centre (T.A.H., R.D.C.), MRC Harwell, Harwell Science and Innovation Campus, Oxfordshire, OX11 0RD, United Kingdom; Department of Medicine (W.D.F.), Norwich Medical School, University of East Anglia, Norwich, NR4 7TJ, United Kingdom; Laboratory of Bioorganic Chemistry (J.H.), National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892; and Albert Einstein College of Medicine (A.M.S.), Bronx, New York 10461
| | - Valerie N Babinsky
- Academic Endocrine Unit (F.M.H., G.V.W., V.N.B., M.A.N., E.K., R.V.T.), Radcliffe Department of Medicine, Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, OX3 7LJ, United Kingdom; Medical Research Council (MRC) Mammalian Genetics Unit and Mary Lyon Centre (T.A.H., R.D.C.), MRC Harwell, Harwell Science and Innovation Campus, Oxfordshire, OX11 0RD, United Kingdom; Department of Medicine (W.D.F.), Norwich Medical School, University of East Anglia, Norwich, NR4 7TJ, United Kingdom; Laboratory of Bioorganic Chemistry (J.H.), National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892; and Albert Einstein College of Medicine (A.M.S.), Bronx, New York 10461
| | - M Andrew Nesbit
- Academic Endocrine Unit (F.M.H., G.V.W., V.N.B., M.A.N., E.K., R.V.T.), Radcliffe Department of Medicine, Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, OX3 7LJ, United Kingdom; Medical Research Council (MRC) Mammalian Genetics Unit and Mary Lyon Centre (T.A.H., R.D.C.), MRC Harwell, Harwell Science and Innovation Campus, Oxfordshire, OX11 0RD, United Kingdom; Department of Medicine (W.D.F.), Norwich Medical School, University of East Anglia, Norwich, NR4 7TJ, United Kingdom; Laboratory of Bioorganic Chemistry (J.H.), National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892; and Albert Einstein College of Medicine (A.M.S.), Bronx, New York 10461
| | - Enikö Kallay
- Academic Endocrine Unit (F.M.H., G.V.W., V.N.B., M.A.N., E.K., R.V.T.), Radcliffe Department of Medicine, Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, OX3 7LJ, United Kingdom; Medical Research Council (MRC) Mammalian Genetics Unit and Mary Lyon Centre (T.A.H., R.D.C.), MRC Harwell, Harwell Science and Innovation Campus, Oxfordshire, OX11 0RD, United Kingdom; Department of Medicine (W.D.F.), Norwich Medical School, University of East Anglia, Norwich, NR4 7TJ, United Kingdom; Laboratory of Bioorganic Chemistry (J.H.), National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892; and Albert Einstein College of Medicine (A.M.S.), Bronx, New York 10461
| | - Tertius A Hough
- Academic Endocrine Unit (F.M.H., G.V.W., V.N.B., M.A.N., E.K., R.V.T.), Radcliffe Department of Medicine, Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, OX3 7LJ, United Kingdom; Medical Research Council (MRC) Mammalian Genetics Unit and Mary Lyon Centre (T.A.H., R.D.C.), MRC Harwell, Harwell Science and Innovation Campus, Oxfordshire, OX11 0RD, United Kingdom; Department of Medicine (W.D.F.), Norwich Medical School, University of East Anglia, Norwich, NR4 7TJ, United Kingdom; Laboratory of Bioorganic Chemistry (J.H.), National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892; and Albert Einstein College of Medicine (A.M.S.), Bronx, New York 10461
| | - William D Fraser
- Academic Endocrine Unit (F.M.H., G.V.W., V.N.B., M.A.N., E.K., R.V.T.), Radcliffe Department of Medicine, Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, OX3 7LJ, United Kingdom; Medical Research Council (MRC) Mammalian Genetics Unit and Mary Lyon Centre (T.A.H., R.D.C.), MRC Harwell, Harwell Science and Innovation Campus, Oxfordshire, OX11 0RD, United Kingdom; Department of Medicine (W.D.F.), Norwich Medical School, University of East Anglia, Norwich, NR4 7TJ, United Kingdom; Laboratory of Bioorganic Chemistry (J.H.), National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892; and Albert Einstein College of Medicine (A.M.S.), Bronx, New York 10461
| | - Roger D Cox
- Academic Endocrine Unit (F.M.H., G.V.W., V.N.B., M.A.N., E.K., R.V.T.), Radcliffe Department of Medicine, Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, OX3 7LJ, United Kingdom; Medical Research Council (MRC) Mammalian Genetics Unit and Mary Lyon Centre (T.A.H., R.D.C.), MRC Harwell, Harwell Science and Innovation Campus, Oxfordshire, OX11 0RD, United Kingdom; Department of Medicine (W.D.F.), Norwich Medical School, University of East Anglia, Norwich, NR4 7TJ, United Kingdom; Laboratory of Bioorganic Chemistry (J.H.), National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892; and Albert Einstein College of Medicine (A.M.S.), Bronx, New York 10461
| | - Jianxin Hu
- Academic Endocrine Unit (F.M.H., G.V.W., V.N.B., M.A.N., E.K., R.V.T.), Radcliffe Department of Medicine, Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, OX3 7LJ, United Kingdom; Medical Research Council (MRC) Mammalian Genetics Unit and Mary Lyon Centre (T.A.H., R.D.C.), MRC Harwell, Harwell Science and Innovation Campus, Oxfordshire, OX11 0RD, United Kingdom; Department of Medicine (W.D.F.), Norwich Medical School, University of East Anglia, Norwich, NR4 7TJ, United Kingdom; Laboratory of Bioorganic Chemistry (J.H.), National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892; and Albert Einstein College of Medicine (A.M.S.), Bronx, New York 10461
| | - Allen M Spiegel
- Academic Endocrine Unit (F.M.H., G.V.W., V.N.B., M.A.N., E.K., R.V.T.), Radcliffe Department of Medicine, Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, OX3 7LJ, United Kingdom; Medical Research Council (MRC) Mammalian Genetics Unit and Mary Lyon Centre (T.A.H., R.D.C.), MRC Harwell, Harwell Science and Innovation Campus, Oxfordshire, OX11 0RD, United Kingdom; Department of Medicine (W.D.F.), Norwich Medical School, University of East Anglia, Norwich, NR4 7TJ, United Kingdom; Laboratory of Bioorganic Chemistry (J.H.), National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892; and Albert Einstein College of Medicine (A.M.S.), Bronx, New York 10461
| | - Rajesh V Thakker
- Academic Endocrine Unit (F.M.H., G.V.W., V.N.B., M.A.N., E.K., R.V.T.), Radcliffe Department of Medicine, Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, OX3 7LJ, United Kingdom; Medical Research Council (MRC) Mammalian Genetics Unit and Mary Lyon Centre (T.A.H., R.D.C.), MRC Harwell, Harwell Science and Innovation Campus, Oxfordshire, OX11 0RD, United Kingdom; Department of Medicine (W.D.F.), Norwich Medical School, University of East Anglia, Norwich, NR4 7TJ, United Kingdom; Laboratory of Bioorganic Chemistry (J.H.), National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892; and Albert Einstein College of Medicine (A.M.S.), Bronx, New York 10461
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Massy ZA, Hénaut L, Larsson TE, Vervloet MG. Calcium-sensing receptor activation in chronic kidney disease: effects beyond parathyroid hormone control. Semin Nephrol 2015; 34:648-59. [PMID: 25498383 DOI: 10.1016/j.semnephrol.2014.10.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Secondary hyperparathyroidism (SHPT) is an important complication of advanced chronic kidney disease (CKD). Cinacalcet, an allosteric modulator of the calcium-sensing receptor (CaSR) expressed in parathyroid glands, is the only calcimimetic approved to treat SHPT in patients on dialysis. By enhancing CaSR sensitivity for plasma extracellular calcium (Ca(2+)0), cinacalcet reduces serum parathyroid hormone, Ca(2+)0, and serum inorganic phosphorous concentrations, allowing better control of SHPT and CKD-mineral and bone disorders. Of interest, the CaSR also is expressed in a variety of tissues where its activation regulates diverse cellular processes, including secretion, apoptosis, and proliferation. Thus, the existence of potential off-target effects of cinacalcet cannot be neglected. This review summarizes our current knowledge concerning the potential role(s) of the CaSR expressed in various tissues in CKD-related disorders, independently of parathyroid hormone control.
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Affiliation(s)
- Ziad A Massy
- Inserm U-1088, University of Picardie Jules Verne, Amiens, France; Division of Nephrology, Ambroise Paré Hospital, Paris-Ile-de-France-Ouest University (University of Versailles Saint-Quentin-En-Yvelines), Paris-Boulogne Billancourt, France.
| | - Lucie Hénaut
- Inserm U-1088, University of Picardie Jules Verne, Amiens, France
| | - Tobias E Larsson
- Department of Clinical Science, Intervention and Technology, Renal Unit, Karolinska Institutet, Stockholm, Sweden; Department of Nephrology, Karolinska University Hospital, Stockholm, Sweden
| | - Marc G Vervloet
- Department of Nephrology and Institute of Cardiovascular Research VU (Institute for Cardiovascular Research of the Vrije Universiteit of Amsterdam), VU University Medical Center, Amsterdam, The Netherlands
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Mace OJ, Tehan B, Marshall F. Pharmacology and physiology of gastrointestinal enteroendocrine cells. Pharmacol Res Perspect 2015. [PMID: 26213627 PMCID: PMC4506687 DOI: 10.1002/prp2.155] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Gastrointestinal (GI) polypeptides are secreted from enteroendocrine cells (EECs). Recent technical advances and the identification of endogenous and synthetic ligands have enabled exploration of the pharmacology and physiology of EECs. Enteroendocrine signaling pathways stimulating hormone secretion involve multiple nutrient transporters and G protein-coupled receptors (GPCRs), which are activated simultaneously under prevailing nutrient conditions in the intestine following a meal. The majority of studies investigate hormone secretion from EECs in response to single ligands and although the mechanisms behind how individual signaling pathways generate a hormonal output have been well characterized, our understanding of how these signaling pathways converge to generate a single hormone secretory response is still in its infancy. However, a picture is beginning to emerge of how nutrients and full, partial, or allosteric GPCR ligands differentially regulate the enteroendocrine system and its interaction with the enteric and central nervous system. So far, activation of multiple pathways underlies drug discovery efforts to harness the therapeutic potential of the enteroendocrine system to mimic the phenotypic changes observed in patients who have undergone Roux-en-Y gastric surgery. Typically obese patients exhibit ∼30% weight loss and greater than 80% of obese diabetics show remission of diabetes. Targeting combinations of enteroendocrine signaling pathways that work synergistically may manifest with significant, differentiated EEC secretory efficacy. Furthermore, allosteric modulators with their increased selectivity, self-limiting activity, and structural novelty may translate into more promising enteroendocrine drugs. Together with the potential to bias enteroendocrine GPCR signaling and/or to activate multiple divergent signaling pathways highlights the considerable range of therapeutic possibilities available. Here, we review the pharmacology and physiology of the EEC system.
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Affiliation(s)
- O J Mace
- Heptares Therapeutics Ltd BioPark, Broadwater Road, Welwyn Garden City, AL7 3AX, United Kingdom
| | - B Tehan
- Heptares Therapeutics Ltd BioPark, Broadwater Road, Welwyn Garden City, AL7 3AX, United Kingdom
| | - F Marshall
- Heptares Therapeutics Ltd BioPark, Broadwater Road, Welwyn Garden City, AL7 3AX, United Kingdom
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29
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Leach K, Conigrave AD, Sexton PM, Christopoulos A. Towards tissue-specific pharmacology: insights from the calcium-sensing receptor as a paradigm for GPCR (patho)physiological bias. Trends Pharmacol Sci 2015; 36:215-25. [PMID: 25765207 DOI: 10.1016/j.tips.2015.02.004] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 02/05/2015] [Accepted: 02/09/2015] [Indexed: 12/25/2022]
Abstract
The calcium-sensing receptor (CaSR) is a widely expressed G protein-coupled receptor (GPCR) that mediates numerous tissue-specific functions. Its multiple ligands and diverse roles attest to the need for exquisite control over the signaling pathways that mediate its effects. 'Biased signaling' is the phenomenon by which distinct ligands stabilize preferred receptor signaling states. The CaSR is subject to biased signaling in response to its endogenous ligands. Interestingly, the 'natural' bias of the CaSR is altered in disease states, and small molecule drugs engender biased allosteric modulation of downstream signaling pathways. Thus, biased signaling from the CaSR also has important implications pathophysiologically and therapeutically. As outlined in this review, this novel paradigm extends to other GPCRs, making the CaSR a model for studies of ligand-biased signaling and for understanding how it may be used to foster selective drug activity in different tissues.
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Affiliation(s)
- Katie Leach
- Monash Institute of Pharmaceutical Sciences, 381 Royal Parade, Parkville VIC, Australia.
| | - Arthur D Conigrave
- School of Molecular Bioscience, Charles Perkins Centre, University of Sydney, NSW 2006, Australia
| | - Patrick M Sexton
- Monash Institute of Pharmaceutical Sciences, 381 Royal Parade, Parkville VIC, Australia
| | - Arthur Christopoulos
- Monash Institute of Pharmaceutical Sciences, 381 Royal Parade, Parkville VIC, Australia
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30
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Zhang C, Miller CL, Brown EM, Yang JJ. The calcium sensing receptor: from calcium sensing to signaling. SCIENCE CHINA-LIFE SCIENCES 2015; 58:14-27. [DOI: 10.1007/s11427-014-4779-y] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2014] [Accepted: 10/21/2014] [Indexed: 12/14/2022]
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31
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Calcium-Sensing Receptor. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2015; 132:127-50. [DOI: 10.1016/bs.pmbts.2015.02.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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32
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Isberg V, de Graaf C, Bortolato A, Cherezov V, Katritch V, Marshall FH, Mordalski S, Pin JP, Stevens RC, Vriend G, Gloriam DE. Generic GPCR residue numbers - aligning topology maps while minding the gaps. Trends Pharmacol Sci 2014; 36:22-31. [PMID: 25541108 DOI: 10.1016/j.tips.2014.11.001] [Citation(s) in RCA: 335] [Impact Index Per Article: 33.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Revised: 11/05/2014] [Accepted: 11/07/2014] [Indexed: 12/31/2022]
Abstract
Generic residue numbers facilitate comparisons of, for example, mutational effects, ligand interactions, and structural motifs. The numbering scheme by Ballesteros and Weinstein for residues within the class A GPCRs (G protein-coupled receptors) has more than 1100 citations, and the recent crystal structures for classes B, C, and F now call for a community consensus in residue numbering within and across these classes. Furthermore, the structural era has uncovered helix bulges and constrictions that offset the generic residue numbers. The use of generic residue numbers depends on convenient access by pharmacologists, chemists, and structural biologists. We review the generic residue numbering schemes for each GPCR class, as well as a complementary structure-based scheme, and provide illustrative examples and GPCR database (GPCRDB) web tools to number any receptor sequence or structure.
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Affiliation(s)
- Vignir Isberg
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Chris de Graaf
- Division of Medicinal Chemistry, Faculty of Sciences, Amsterdam Institute for Molecules, Medicines and Systems, VU University Amsterdam, The Netherlands
| | | | - Vadim Cherezov
- The Bridge@USC, Department of Chemistry, University of Southern California, Los Angeles, CA 90089 USA
| | - Vsevolod Katritch
- The Bridge@USC, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089 USA
| | | | - Stefan Mordalski
- Department of Medicinal Chemistry, Institute of Pharmacology, Polish Academy of Sciences, Krakow, Poland; Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
| | - Jean-Philippe Pin
- Institute of Functional Genomics, Centre National de la Recherche Scientifique (CNRS) Unité Mixte de Recherche 5203, Universities Montpellier, Montpellier, France; Institut National de la Santé et de la Recherche Médicale (INSERM) Unité 661, Montpellier, France
| | - Raymond C Stevens
- The Bridge@USC, Department of Chemistry, University of Southern California, Los Angeles, CA 90089 USA; The Bridge@USC, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089 USA
| | - Gerrit Vriend
- Centre for Molecular and Biomolecular Informatics (CMBI), Radboudumc, Nijmegen, The Netherlands
| | - David E Gloriam
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
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Quiniou C, Domínguez-Punaro M, Cloutier F, Erfani A, Ennaciri J, Sivanesan D, Sanchez M, Chognard G, Hou X, Rivera JC, Beauchamp C, Charron G, Vilquin M, Kuchroo V, Michnick S, Rioux JD, Lesage S, Chemtob S. Specific targeting of the IL-23 receptor, using a novel small peptide noncompetitive antagonist, decreases the inflammatory response. Am J Physiol Regul Integr Comp Physiol 2014; 307:R1216-30. [DOI: 10.1152/ajpregu.00540.2013] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
IL-23 is part of the IL-12 family of cytokines and is composed of the p19 subunit specific to IL-23 and the p40 subunit shared with IL-12. IL-23 specifically contributes to the inflammatory process of multiple chronic inflammatory autoimmune disorders, including psoriasis, multiple sclerosis, inflammatory bowel disease, and rheumatoid arthritis. So far, one antibody targeting the shared p40 subunit of IL-12 and IL-23, Ustekinumab, is approved clinically to treat psoriasis. However, there are no treatments inhibiting specifically the IL-23 proinflammatory response. We have developed small IL-23R-specific antagonists by designing all D-peptides arising from flexible regions of IL-23R. Of these peptides, we selected 2305 (teeeqqly), since in addition to its soluble properties, it inhibited IL-23-induced STAT3 phosphorylation in spleen cells. Peptide 2305 specifically binds to IL-23R/IL-12Rβ1-expressing HEK-293 cells and not to cells devoid of the receptor. Peptide 2305 showed functional selectivity by modulating IL-23-induced gene expression in IL-23R/IL-12Rβ1-expressing cells and in Jurkat cells; 2305 does not inhibit IL-12-induced cytokine expression in IL-12Rβ-IL-12Rβ2-HEK-293 cells. Finally, compared with anti-p40 treatment, 2305 effectively and selectively inhibits IL-23-induced inflammation in three in vivo mouse models: IL-23-induced ear inflammation, anti-CD40-induced systemic inflammatory response, and collagen-induced arthritis. We, hereby, describe the discovery and characterization of a potent IL-23R small-peptide modulator, 2305 (teeeqqly), that is effective in vivo. 2305 may be more convenient, less cumbersome, less costly, and most importantly, more specific than current biologics for the treatment of inflammatory conditions, and conceivably complement the actual therapies for these chronic and debilitating inflammatory diseases.
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Affiliation(s)
- Christiane Quiniou
- Departments of Pediatrics, Ophthalmology and Pharmacology, Centre Hospitalier Universitaire Sainte-Justine Research Centre, Montréal, Canada
| | | | - Frank Cloutier
- Departments of Pediatrics, Ophthalmology and Pharmacology, Centre Hospitalier Universitaire Sainte-Justine Research Centre, Montréal, Canada
| | - Atefeh Erfani
- Departments of Pediatrics, Ophthalmology and Pharmacology, Centre Hospitalier Universitaire Sainte-Justine Research Centre, Montréal, Canada
| | - Jamila Ennaciri
- Departments of Pediatrics, Ophthalmology and Pharmacology, Centre Hospitalier Universitaire Sainte-Justine Research Centre, Montréal, Canada
| | - Durgajini Sivanesan
- Department of Pharmacology and Therapeutics, McGill University, Montréal, Canada
| | - Mélanie Sanchez
- Department of Biochemistry, Université de Montréal, Montréal, Canada
| | - Gaëlle Chognard
- Maisonneuve-Rosemont Hospital, Research Center, Montreal, Canada
- Department of Microbiology and Immunology, Université de Montréal, Montréal, Canada
| | - Xin Hou
- Departments of Pediatrics, Ophthalmology and Pharmacology, Centre Hospitalier Universitaire Sainte-Justine Research Centre, Montréal, Canada
| | | | | | | | - Marie Vilquin
- Maisonneuve-Rosemont Hospital, Research Center, Montreal, Canada
| | - Vijay Kuchroo
- Center for Neurologic Diseases, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts; and
| | - Stephen Michnick
- Department of Pharmacology and Therapeutics, McGill University, Montréal, Canada
| | - John D. Rioux
- Montreal Heart Institute, Montréal, Canada
- Department of Medicine, Université de Montréal, Montréal, Canada
| | - Sylvie Lesage
- Maisonneuve-Rosemont Hospital, Research Center, Montreal, Canada
- Department of Microbiology and Immunology, Université de Montréal, Montréal, Canada
| | - Sylvain Chemtob
- Departments of Pediatrics, Ophthalmology and Pharmacology, Centre Hospitalier Universitaire Sainte-Justine Research Centre, Montréal, Canada
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34
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Dal Prà I, Chiarini A, Pacchiana R, Gardenal E, Chakravarthy B, Whitfield JF, Armato U. Calcium-Sensing Receptors of Human Astrocyte-Neuron Teams: Amyloid-β-Driven Mediators and Therapeutic Targets of Alzheimer's Disease. Curr Neuropharmacol 2014; 12:353-64. [PMID: 25342943 PMCID: PMC4207075 DOI: 10.2174/1570159x12666140828214701] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Revised: 06/19/2014] [Accepted: 06/26/2014] [Indexed: 12/24/2022] Open
Abstract
It is generally assumed that the neuropathology of sporadic (late-onset or nonfamilial) Alzheimer’s disease (AD) is driven by the overproduction and spreading of first Amyloid-βx-42 (Aβ42) and later hyperphosphorylated (hp)-Tau oligomeric “infectious seeds”. Hitherto, only neurons were held to make and spread both oligomer types; astrocytes would just remove debris. However, we have recently shown that exogenous fibrillar or soluble Aβ peptides specifically bind and activate the Ca2+-sensing receptors (CaSRs) of untransformed human cortical adult astrocytes and postnatal neurons cultured in vitro driving them to produce, accrue, and secrete surplus endogenous Aβ42. While the Aβ-exposed neurons start dying, astrocytes survive and keep oversecreting Aβ42, nitric oxide (NO), and vascular endothelial growth factor (VEGF)-A. Thus astrocytes help neurons’ demise. Moreover, we have found that a highly selective allosteric CaSR agonist (“calcimimetic”), NPS R-568, mimics the just mentioned neurotoxic actions triggered by Aβ●CaSR signaling. Contrariwise, and most important, NPS 2143, a highly selective allosteric CaSR antagonist (“calcilytic”), fully suppresses all the Aβ●CaSR signaling-driven noxious actions. Altogether our findings suggest that the progression of AD neuropathology is promoted by unceasingly repeating cycles of accruing exogenous Aβ42 oligomers interacting with the CaSRs of swelling numbers of astrocyte-neuron teams thereby recruiting them to overrelease additional Aβ42 oligomers, VEGF-A, and NO. Calcilytics would beneficially break such Aβ/CaSR-driven vicious cycles and hence halt or at least slow the otherwise unstoppable spreading of AD neuropathology
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Affiliation(s)
- I Dal Prà
- Histology & Embryology Section, Department of Life & Reproduction Sciences, University of Verona Medical School, Verona, Venetia, Italy
| | - A Chiarini
- Histology & Embryology Section, Department of Life & Reproduction Sciences, University of Verona Medical School, Verona, Venetia, Italy
| | - R Pacchiana
- Histology & Embryology Section, Department of Life & Reproduction Sciences, University of Verona Medical School, Verona, Venetia, Italy
| | - E Gardenal
- Histology & Embryology Section, Department of Life & Reproduction Sciences, University of Verona Medical School, Verona, Venetia, Italy
| | - B Chakravarthy
- National Research Council of Canada, Ottawa, Ontario, Canada
| | - J F Whitfield
- National Research Council of Canada, Ottawa, Ontario, Canada
| | - U Armato
- Histology & Embryology Section, Department of Life & Reproduction Sciences, University of Verona Medical School, Verona, Venetia, Italy
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35
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Goolam MA, Ward JH, Avlani VA, Leach K, Christopoulos A, Conigrave AD. Roles of intraloops-2 and -3 and the proximal C-terminus in signalling pathway selection from the human calcium-sensing receptor. FEBS Lett 2014; 588:3340-6. [PMID: 25080008 DOI: 10.1016/j.febslet.2014.07.022] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2014] [Revised: 07/03/2014] [Accepted: 07/16/2014] [Indexed: 12/24/2022]
Abstract
The calcium-sensing receptor (CaSR) couples to signalling pathways via intracellular loops 2 and 3, and the C-terminus. However, the requirements for signalling are largely undefined. We investigated the impacts of selected point mutations in iL-2 (F706A) and iL-3 (L797A and E803A), and a truncation of the C-terminus (R866X) on extracellular Ca(2+) (Ca(2+)o)-stimulated phosphatidylinositol-specific phospholipase-C (PI-PLC) and various other signalling responses. CaSR-mediated activation of PI-PLC was markedly attenuated in all four mutants and similar suppressions were observed for Ca(2+)o-stimulated ERK1/2 phosphorylation. Ca(2+)o-stimulated intracellular Ca(2+) (Ca(2+)i) mobilization, however, was relatively preserved for the iL-2 and iL-3 mutants and suppression of adenylyl cyclase was unaffected by either E803A or R866X. The CaSR selects for specific signalling pathways via the proximal C-terminus and key residues in iL-2, iL-3.
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Affiliation(s)
- Mahvash A Goolam
- School of Molecular Bioscience, University of Sydney, NSW 2006, Australia
| | - James H Ward
- School of Molecular Bioscience, University of Sydney, NSW 2006, Australia
| | - Vimesh A Avlani
- School of Molecular Bioscience, University of Sydney, NSW 2006, Australia
| | - Katie Leach
- Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria 3052, Australia
| | - Arthur Christopoulos
- Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria 3052, Australia
| | - Arthur D Conigrave
- School of Molecular Bioscience, University of Sydney, NSW 2006, Australia.
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Wu H, Wang C, Gregory KJ, Han GW, Cho HP, Xia Y, Niswender CM, Katritch V, Meiler J, Cherezov V, Conn PJ, Stevens RC. Structure of a class C GPCR metabotropic glutamate receptor 1 bound to an allosteric modulator. Science 2014; 344:58-64. [PMID: 24603153 DOI: 10.1126/science.1249489] [Citation(s) in RCA: 394] [Impact Index Per Article: 39.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The excitatory neurotransmitter glutamate induces modulatory actions via the metabotropic glutamate receptors (mGlus), which are class C G protein-coupled receptors (GPCRs). We determined the structure of the human mGlu1 receptor seven-transmembrane (7TM) domain bound to a negative allosteric modulator, FITM, at a resolution of 2.8 angstroms. The modulator binding site partially overlaps with the orthosteric binding sites of class A GPCRs but is more restricted than most other GPCRs. We observed a parallel 7TM dimer mediated by cholesterols, which suggests that signaling initiated by glutamate's interaction with the extracellular domain might be mediated via 7TM interactions within the full-length receptor dimer. A combination of crystallography, structure-activity relationships, mutagenesis, and full-length dimer modeling provides insights about the allosteric modulation and activation mechanism of class C GPCRs.
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Affiliation(s)
- Huixian Wu
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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Wootten D, Christopoulos A, Sexton PM. Emerging paradigms in GPCR allostery: implications for drug discovery. Nat Rev Drug Discov 2013; 12:630-44. [PMID: 23903222 DOI: 10.1038/nrd4052] [Citation(s) in RCA: 350] [Impact Index Per Article: 31.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Allosteric ligands bind to G protein-coupled receptors (GPCRs; also known as seven-transmembrane receptors) at sites that are distinct from the sites to which endogenous ligands bind. The existence of allosteric ligands has enriched the ways in which the functions of GPCRs can be manipulated for potential therapeutic benefit, yet the complexity of their actions provides both challenges and opportunities for drug screening and development. Converging avenues of research in areas such as biased signalling by allosteric ligands and the mechanisms by which allosteric ligands modulate the effects of diverse endogenous ligands have provided new insights into how interactions between allosteric ligands and GPCRs could be exploited for drug discovery. These new findings have the potential to alter how screening for allosteric drugs is performed and may increase the chances of success in the development of allosteric modulators as clinical lead compounds.
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Affiliation(s)
- Denise Wootten
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Melbourne, Victoria 3052, Australia
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38
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Breitwieser GE. Pharmacoperones and the calcium sensing receptor: exogenous and endogenous regulators. Pharmacol Res 2013; 83:30-7. [PMID: 24291533 DOI: 10.1016/j.phrs.2013.11.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Revised: 11/15/2013] [Accepted: 11/18/2013] [Indexed: 01/05/2023]
Abstract
Calcium sensing receptor (CaSR) mutations or altered expression cause disorders of calcium handling. Recent studies suggest that reduced targeting to the plasma membrane is a feature common to many CaSR loss-of-function mutations. Allosteric agonists (calcimimetics) can rescue signaling of a subset of CaSR mutants. This review evaluates our current understanding of the subcellular site(s) for allosteric modulator rescue of CaSR mutants. Studies to date make a strong case for calcimimetic potentiation of signaling not only at plasma membrane-localized CaSR, but at the endoplasmic reticulum, acting as pharmacoperones to assist in navigation of multiple quality control checkpoints. The possible role of endogenous pharmacoperones, calcium and glutathione, in folding and stabilization of the CaSR extracellular and transmembrane domains are considered. Finally, the possibility that dihydropyridines act as unintended pharmacoperones of CaSR is proposed. While our understanding of pharmacoperone rescue of CaSR requires refinement, promising results to date argue that this may be a fruitful avenue for drug discovery.
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Affiliation(s)
- Gerda E Breitwieser
- Weis Center for Research, Geisinger Clinic, 100N. Academy Avenue, Danville PA 17822-2604, USA.
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39
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Turlington M, Noetzel MJ, Chun A, Zhou Y, Gogliotti RD, Nguyen ED, Gregory KJ, Vinson PN, Rook JM, Gogi KK, Xiang Z, Bridges TM, Daniels JS, Jones C, Niswender CM, Meiler J, Conn PJ, Lindsley CW, Stauffer SR. Exploration of allosteric agonism structure-activity relationships within an acetylene series of metabotropic glutamate receptor 5 (mGlu5) positive allosteric modulators (PAMs): discovery of 5-((3-fluorophenyl)ethynyl)-N-(3-methyloxetan-3-yl)picolinamide (ML254). J Med Chem 2013; 56:7976-96. [PMID: 24050755 PMCID: PMC3908770 DOI: 10.1021/jm401028t] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Positive allosteric modulators (PAMs) of metabotropic glutamate receptor 5 (mGlu5) represent a promising therapeutic strategy for the treatment of schizophrenia. Both allosteric agonism and high glutamate fold-shift have been implicated in the neurotoxic profile of some mGlu5 PAMs; however, these hypotheses remain to be adequately addressed. To develop tool compounds to probe these hypotheses, the structure-activity relationship of allosteric agonism was examined within an acetylenic series of mGlu5 PAMs exhibiting allosteric agonism in addition to positive allosteric modulation (ago-PAMs). PAM 38t, a low glutamate fold-shift allosteric ligand (maximum fold-shift ~ 3.0), was selected as a potent PAM with no agonism in the in vitro system used for compound characterization and in two native electrophysiological systems using rat hippocampal slices. PAM 38t (ML254) will be useful to probe the relative contribution of cooperativity and allosteric agonism to the adverse effect liability and neurotoxicity associated with this class of mGlu5 PAMs.
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Affiliation(s)
- Mark Turlington
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Vanderbilt Specialized Chemistry Center for Probe Development (MLPCN), Nashville, TN 37232, USA
| | - Meredith J. Noetzel
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Aspen Chun
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Vanderbilt Specialized Chemistry Center for Probe Development (MLPCN), Nashville, TN 37232, USA
| | - Ya Zhou
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Vanderbilt Specialized Chemistry Center for Probe Development (MLPCN), Nashville, TN 37232, USA
| | - Rocco D. Gogliotti
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Vanderbilt Specialized Chemistry Center for Probe Development (MLPCN), Nashville, TN 37232, USA
| | - Elizabeth D. Nguyen
- Center for Structural Biology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Karen J. Gregory
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052
| | - Paige N. Vinson
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Jerri M. Rook
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Kiran K. Gogi
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Zixiu Xiang
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Thomas M. Bridges
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Vanderbilt Specialized Chemistry Center for Probe Development (MLPCN), Nashville, TN 37232, USA
| | - J. Scott Daniels
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Vanderbilt Specialized Chemistry Center for Probe Development (MLPCN), Nashville, TN 37232, USA
| | - Carrie Jones
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Vanderbilt Specialized Chemistry Center for Probe Development (MLPCN), Nashville, TN 37232, USA
| | - Colleen M. Niswender
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Vanderbilt Specialized Chemistry Center for Probe Development (MLPCN), Nashville, TN 37232, USA
| | - Jens Meiler
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN 37232, USA
- Center for Structural Biology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Vanderbilt Institute for Chemical Biology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - P. Jeffrey Conn
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Vanderbilt Specialized Chemistry Center for Probe Development (MLPCN), Nashville, TN 37232, USA
| | - Craig W. Lindsley
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Vanderbilt Specialized Chemistry Center for Probe Development (MLPCN), Nashville, TN 37232, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN 37232, USA
| | - Shaun R. Stauffer
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA
- Vanderbilt Specialized Chemistry Center for Probe Development (MLPCN), Nashville, TN 37232, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN 37232, USA
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40
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Conigrave AD, Ward DT. Calcium-sensing receptor (CaSR): pharmacological properties and signaling pathways. Best Pract Res Clin Endocrinol Metab 2013; 27:315-31. [PMID: 23856262 DOI: 10.1016/j.beem.2013.05.010] [Citation(s) in RCA: 151] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
In this article we consider the mechanisms by which the calcium-sensing receptor (CaSR) induces its cellular responses via the control (activation or inhibition) of signaling pathways. We consider key features of CaSR-mediated signaling including its control of the heterotrimeric G-proteins Gq/11, Gi/o and G12/13 and the downstream consequences recognizing that very few CaSR-mediated cell phenomena have been fully described. We also consider the manner in which the CaSR contributes to the formation of specific signaling scaffolds via peptide recognition sequences in its intracellular C-terminal along with the origins of its high level of cooperativity, particularly for Ca(2+)o, and its remarkable resistance to desensitization. We also consider the nature of the mechanisms by which the CaSR controls oscillatory and sustained Ca(2+)i mobilizing responses and inhibits or elevates cyclic adenosine monophosphate (cAMP) levels dependent on the cellular and signaling context. Finally, we consider the diversity of the receptor's ligands, ligand binding sites and broader compartment-dependent physiological roles leading to the identification of pronounced ligand-biased signaling for agonists including Sr(2+) and modulators including l-amino acids and the clinically effective calcimimetic cinacalcet. We note the implications of these findings for the development of new designer drugs that might target the CaSR in pathophysiological contexts beyond those established for the treatment of disorders of calcium metabolism.
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Affiliation(s)
- Arthur D Conigrave
- School of Molecular Bioscience, University of Sydney, NSW 2006, Australia.
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41
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Hendy GN, Canaff L, Cole DEC. The CASR gene: alternative splicing and transcriptional control, and calcium-sensing receptor (CaSR) protein: structure and ligand binding sites. Best Pract Res Clin Endocrinol Metab 2013; 27:285-301. [PMID: 23856260 DOI: 10.1016/j.beem.2013.02.009] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The calcium-sensing receptor (CaSR) is a G protein-coupled receptor encoded by a single copy gene. The human CASR gene spans ~103-kb and has eight exons. Promoters P1 and P2 drive transcription of exons 1A and 1B, respectively, encoding alternative 5'-UTRs that splice to exon 2 encoding the common part of the 5'-UTR. Exons 2-7 encode the CaSR protein of 1078 amino acids. Functional elements responsive to 1,25-dihydroxyvitamin D, proinflammatory cytokines, and glial cells missing-2 are present in the CASR promoters. Evolutionarily, the exon structure, first seen in aquatic vertebrates, is well-conserved with a single linkage disequilibrium haplotype block for protein coding exons 2-7. Structural features of the human CaSR protein are: an N-terminal signal peptide (19 amino acids (aa)); an extracellular domain (~600 aa) having a bi-lobed Venus Flytrap (VFT) domain with several Ca(2+)-binding sites; and a nine-cysteines domain that transduces the activation signal to the 7-transmembrane domain (250 aa) and the C-terminal tail (216 aa).
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Affiliation(s)
- Geoffrey N Hendy
- Calcium Research Laboratory, and Hormones and Cancer Research Unit, Royal Victoria Hospital and McGill University Health Centre, Montreal, QC H3A 1A1, Canada.
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42
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Avlani VA, Ma W, Mun HC, Leach K, Delbridge L, Christopoulos A, Conigrave AD. Calcium-sensing receptor-dependent activation of CREB phosphorylation in HEK293 cells and human parathyroid cells. Am J Physiol Endocrinol Metab 2013; 304:E1097-104. [PMID: 23531616 DOI: 10.1152/ajpendo.00054.2013] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In addition to its acute effects on hormone secretion, epithelial transport, and shape change, the calcium-sensing receptor (CaSR) modulates the expression of genes that control cell survival, proliferation, and differentiation as well as the synthesis of peptide hormones and enzymes. In the present study, we investigated the impacts of a CaSR agonist and several CaSR modulators on phosphorylation of transcription factor CREB residue Ser(133) in CaSR-expressing HEK293 (HEK-CaSR) cells and human adenomatous parathyroid cells. Elevated Ca(2+)o concentration had no effect on CREB phosphorylation (p-CREB) in control HEK293 cells but stimulated p-CREB in both HEK-CaSR cells and human parathyroid cells. In addition, p-CREB was stimulated by the positive modulator cinacalcet and inhibited by the negative modulator NPS 2143 in both CaSR-expressing cell types. Two positive modulators that bind in the receptor's Venus Fly Trap domain, l-phenylalanine and S-methylglutathione, had no effect on p-CREB in HEK-CaSR cells, demonstrating the existence of pronounced signaling bias. Analysis of the signaling pathways using specific inhibitors demonstrated that phosphoinositide-specific phospholipase C and conventional protein kinase C isoforms make major contributions to Ca(2+)o-induced p-CREB in both cell-types, suggesting key roles for Gq/11. In addition, in parathyroid cells but not HEK-CaSR cells, activation of p-CREB was dependent on Gi/o, demonstrating the existence of cell type-specific signaling.
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Affiliation(s)
- Vimesh A Avlani
- School of Molecular Bioscience, University of Sydney, Sydney, New South Wales, Australia
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Yanagawa M, Yamashita T, Shichida Y. Glutamate acts as a partial inverse agonist to metabotropic glutamate receptor with a single amino acid mutation in the transmembrane domain. J Biol Chem 2013; 288:9593-9601. [PMID: 23420844 PMCID: PMC3617263 DOI: 10.1074/jbc.m112.437780] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Revised: 02/15/2013] [Indexed: 11/06/2022] Open
Abstract
Metabotropic glutamate receptor (mGluR), a prototypical family 3 G protein-coupled receptor (GPCR), has served as a model for studying GPCR dimerization, and growing evidence has revealed that a glutamate-induced dimeric rearrangement promotes activation of the receptor. However, structural information of the seven-transmembrane domain is severely limited, in contrast to the well studied family 1 GPCRs including rhodopsins and adrenergic receptors. Homology modeling of mGluR8 transmembrane domain with rhodopsin as a template suggested the presence of a conserved water-mediated hydrogen-bonding network between helices VI and VII, which presumably constrains the receptor in an inactive conformation. We therefore conducted a mutational analysis to assess structural similarities between mGluR and family 1 GPCRs. Mutational experiments confirmed that the disruption of the hydrogen-bonding network by T789Y(6.43) mutation induced high constitutive activity. Unexpectedly, this high constitutive activity was suppressed by glutamate, the natural agonist ligand, indicating that glutamate acts as a partial inverse agonist to this mutant. Fluorescence energy transfer analysis of T789Y(6.43) suggested that the glutamate-induced reduction of the activity originated not from the dimeric rearrangement but from conformational changes within each protomer. Double mutational analysis showed that the specific interaction between Tyr-789(6.43) and Gly-831(7.45) in T789Y(6.43) mutant was important for this phenotype. Therefore, the present study is consistent with the notion that the metabotropic glutamate receptor shares a common activation mechanism with family 1 GPCRs, where rearrangement between helices VI and VII causes the active state formation.
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Affiliation(s)
- Masataka Yanagawa
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Takahiro Yamashita
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Yoshinori Shichida
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
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Leach K, Wen A, Cook AE, Sexton PM, Conigrave AD, Christopoulos A. Impact of clinically relevant mutations on the pharmacoregulation and signaling bias of the calcium-sensing receptor by positive and negative allosteric modulators. Endocrinology 2013; 154:1105-16. [PMID: 23372019 DOI: 10.1210/en.2012-1887] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Cinacalcet is predominantly used to treat secondary hyperparathyroidism due to end-stage renal failure, but, more recently, its potential clinical efficacy in treating patients with loss-of-function mutations in the calcium-sensing receptor (CaSR) has been recognized. Many clinically relevant CaSR mutations are located in the heptahelical membrane spanning and extracellular loop regions of the receptor, where allosteric modulators are predicted to bind. The aim of the present study was to investigate the impact of such mutations on the pharmacoregulation of the CaSR by the positive and negative allosteric modulators, cinacalcet and NPS-2143, respectively. Both cinacalcet and NPS-2143 effectively rescued mutants whose cell surface expression was substantially impaired, suggesting that both classes of drug can stabilize a receptor conformation that is trafficked more effectively to the cell surface. In addition, functional impairments in almost all mutant CaSRs were rescued by either cinacalcet or NPS-2143 via restoration of intracellular signaling. There was a significantly greater ability of both compounds to modulate agonist-stimulated intracellular Ca(2+) mobilization than ERK1/2 phosphorylation, indicating that the allosteric modulators engender bias in agonist-stimulated CaSR signaling to different pathways. Three mutations (G(670)R, P(748)R, and L(773)R) altered the binding affinity of allosteric modulators to the CaSR, and 3 mutations (V(817)I, L(773)R, and E(767)K) altered the cooperativity between the allosteric modulator and Ca(2+)(o). These findings have important implications for the treatment of diseases associated with CaSR mutations using allosteric CaSR modulators and for analyzing the effects of mutations on the function and pharmacoregulation of the CaSR.
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Affiliation(s)
- Katie Leach
- Monash Institute of Pharmaceutical Sciences, 399 Royal Parade, Parkville, 3052, Victoria, Australia.
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45
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Gregory KJ, Nguyen ED, Reiff SD, Squire EF, Stauffer SR, Lindsley CW, Meiler J, Conn PJ. Probing the metabotropic glutamate receptor 5 (mGlu₅) positive allosteric modulator (PAM) binding pocket: discovery of point mutations that engender a "molecular switch" in PAM pharmacology. Mol Pharmacol 2013; 83:991-1006. [PMID: 23444015 DOI: 10.1124/mol.112.083949] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Positive allosteric modulation of metabotropic glutamate receptor subtype 5 (mGlu₅) is a promising novel approach for the treatment of schizophrenia and cognitive disorders. Allosteric binding sites are topographically distinct from the endogenous ligand (orthosteric) binding site, allowing for co-occupation of a single receptor with the endogenous ligand and an allosteric modulator. Negative allosteric modulators (NAMs) inhibit and positive allosteric modulators (PAMs) enhance the affinity and/or efficacy of the orthosteric agonist. The molecular determinants that govern mGlu₅ modulator affinity versus cooperativity are not well understood. Focusing on the modulators based on the acetylene scaffold, we sought to determine the molecular interactions that contribute to PAM versus NAM pharmacology. Generation of a comparative model of the transmembrane-spanning region of mGlu₅ served as a tool to predict and interpret the impact of mutations in this region. Application of an operational model of allosterism allowed for determination of PAM and NAM affinity estimates at receptor constructs that possessed no detectable radioligand binding as well as delineation of effects on affinity versus cooperativity. Novel mutations within the transmembrane domain (TM) regions were identified that had differential effects on acetylene PAMs versus 2-methyl-6-(phenylethynyl)-pyridine, a prototypical NAM. Three conserved amino acids (Y658, T780, and S808) and two nonconserved residues (P654 and A809) were identified as key determinants of PAM activity. Interestingly, we identified two point mutations in TMs 6 and 7 that, when mutated, engender a mode switch in the pharmacology of certain PAMs.
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Affiliation(s)
- Karen J Gregory
- Department of Pharmacology and Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232-0697, USA
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46
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Leach K, Wen A, Davey AE, Sexton PM, Conigrave AD, Christopoulos A. Identification of molecular phenotypes and biased signaling induced by naturally occurring mutations of the human calcium-sensing receptor. Endocrinology 2012; 153:4304-16. [PMID: 22798347 DOI: 10.1210/en.2012-1449] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
More than 200 naturally occurring mutations have been identified in the human CaSR, which have been linked to diseases involving dysregulation of extracellular Ca(2+) homeostasis. These mutations have classically been termed "loss-" or "gain-of-function" mutations, which is an oversimplification given that amino acid changes can alter numerous molecular properties of a receptor. We thus sought to characterize the effects of 21 clinically relevant mutations, the majority located in the heptahelical domains and extracellular loop regions of the CaSR, using flow cytometry to measure cell surface receptor expression levels, and measurements of intracellular Ca(2+) mobilization and ERK1/2 phosphorylation to monitor receptor signaling. We identified distinct molecular phenotypes caused by these naturally occurring amino acid substitutions, which included combinations of loss- and gain-of-expression and changes in intrinsic signaling capacity. Importantly, we also identified biased signaling in the response of the CaSR to different mutations across the two pathways, indicating that some mutations resulted in receptor conformations that differentially altered receptor-coupling preferences. These findings have important implications for understanding the causes of diseases linked to the CaSR. A full appreciation of the molecular effects of these amino acid changes may enable the development of therapeutics that specifically target the molecular determinant of impairment in the receptor.
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Affiliation(s)
- Katie Leach
- Monash Institute of Pharmaceutical Sciences, 399 Royal Parade, Parkville, 3052, Victoria, Australia.
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47
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Membrane-sensitive conformational states of helix 8 in the metabotropic Glu2 receptor, a class C GPCR. PLoS One 2012; 7:e42023. [PMID: 22870276 PMCID: PMC3411606 DOI: 10.1371/journal.pone.0042023] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Accepted: 06/29/2012] [Indexed: 11/19/2022] Open
Abstract
The recent elucidation of the X-ray structure of several class A GPCRs clearly indicates that the amphipathic helix 8 (H8) is a conserved structural domain in most crystallized GPCRs. Very little is known about the presence and the possible role of an analogous H8 domain in the distantly related class C GPCRs. In this study, we investigated the structural properties for the H8 domain of the mGluR2 receptor, a class C GPCR, by applying extended molecular dynamics simulations. Our study indicates that the amphipathic H8 adopts membrane-sensitive conformational states, which depend on the membrane composition. Cholesterol-rich membranes stabilize the helical structure of H8 whereas cholesterol-depleted membranes induce a disruption of H8. The observed link between membrane cholesterol levels and H8 conformational states suggests that H8 behaves as a sensor of cholesterol concentration.
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48
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Cavanaugh A, Huang Y, Breitwieser GE. Behind the curtain: cellular mechanisms for allosteric modulation of calcium-sensing receptors. Br J Pharmacol 2012; 165:1670-1677. [PMID: 21470201 DOI: 10.1111/j.1476-5381.2011.01403.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Calcium-sensing receptors (CaSR) are integral to regulation of systemic Ca(2+) homeostasis. Altered expression levels or mutations in CaSR cause Ca(2+) handling diseases. CaSR is regulated by both endogenous allosteric modulators and allosteric drugs, including the first Food and Drug Administration-approved allosteric agonist, Cinacalcet HCl (Sensipar®). Recent studies suggest that allosteric modulators not only alter function of plasma membrane-localized CaSR, but regulate CaSR stability at the endoplasmic reticulum. This brief review summarizes our current understanding of the role of membrane-permeant allosteric agonists in cotranslational stabilization of CaSR, and highlights additional, indirect, signalling-dependent role(s) for membrane-impermeant allosteric drugs. Overall, these studies suggest that allosteric drugs act at multiple cellular organelles to control receptor abundance and hence function, and that drug hydrophobicity can bias the relative contributions of plasma membrane and intracellular organelles to CaSR abundance and signalling.
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Affiliation(s)
- Alice Cavanaugh
- Weis Center for Research, Geisinger Clinic, Danville, PA, USACancer Drug Research Laboratory, McGill University/Royal Victoria Hospital, Montreal, QC, Canada
| | - Ying Huang
- Weis Center for Research, Geisinger Clinic, Danville, PA, USACancer Drug Research Laboratory, McGill University/Royal Victoria Hospital, Montreal, QC, Canada
| | - Gerda E Breitwieser
- Weis Center for Research, Geisinger Clinic, Danville, PA, USACancer Drug Research Laboratory, McGill University/Royal Victoria Hospital, Montreal, QC, Canada
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Breitwieser GE. Minireview: the intimate link between calcium sensing receptor trafficking and signaling: implications for disorders of calcium homeostasis. Mol Endocrinol 2012; 26:1482-95. [PMID: 22745192 DOI: 10.1210/me.2011-1370] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The calcium-sensing receptor (CaSR) regulates organismal Ca(2+) homeostasis. Dysregulation of CaSR expression or mutations in the CASR gene cause disorders of Ca(2+) homeostasis and contribute to the progression or severity of cancers and cardiovascular disease. This brief review highlights recent findings that define the CaSR life cycle, which controls the cellular abundance of CaSR and CaSR signaling. A novel mechanism, termed agonist-driven insertional signaling (ADIS), contributes to the unique hallmarks of CaSR signaling, including the high degree of cooperativity and the lack of functional desensitization. Agonist-mediated activation of plasma membrane-localized CaSR increases the rate of insertion of CaSR at the plasma membrane without altering the constitutive endocytosis rate, thereby acutely increasing the maximum signaling response. Prolonged CaSR signaling requires a large intracellular ADIS-mobilizable pool of CaSR, which is maintained by signaling-mediated increases in biosynthesis. This model provides a rational framework for characterizing the defects caused by CaSR mutations and the altered functional expression of wild-type CaSR in disease states. Mechanistic dissection of ADIS of CaSR should lead to optimized pharmacological approaches to normalize CaSR signaling in disorders of Ca(2+) homeostasis.
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Affiliation(s)
- Gerda E Breitwieser
- Weis Center for Research, Geisinger Clinic, Danville, Pennsylvania 17822-2604, USA.
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Huang Y, Cavanaugh A, Breitwieser GE. Regulation of stability and trafficking of calcium-sensing receptors by pharmacologic chaperones. ADVANCES IN PHARMACOLOGY 2012; 62:143-73. [PMID: 21907909 DOI: 10.1016/b978-0-12-385952-5.00007-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Gain- or loss-of-function mutations and polymorphisms of the calcium-sensing receptor (CaSR) cause Ca(2+) handling diseases. Altered expression and/or signaling of wild-type CaSR can also contribute to pathology. Recent studies have demonstrated that a significant proportion of mutations cause altered targeting and/or trafficking of CaSR to the plasma membrane. Pharmacological approaches to rescue of CaSR function include treatment with allosteric modulators, which potentiate the effects of the orthosteric agonist Ca(2+). Dissection of the mechanism(s) contributing to allosteric agonist-mediated rescue of loss-of-function CaSR mutants has demonstrated pharmacologic chaperone actions coincident with CaSR biosynthesis. The distinctive responses to the allosteric agonist (NPS R-568), which promotes CaSR stability, and the allosteric antagonist (NPS 2143), which promotes CaSR degradation, have led to a model for a conformational checkpoint during CaSR biosynthesis. The conformational checkpoint would "tune" CaSR biosynthesis to cellular signaling state. Navigation of a distinct checkpoint for endoplasmic release can also be augmented by pharmacologic chaperones. The diverse, post-endoplasmic reticulum quality control site(s) for pharmacologic chaperone modulation of CaSR stability and trafficking redefines the role(s) of allosteric modulators in regulation of overall GPCR function.
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Affiliation(s)
- Ying Huang
- Cancer Drug Research Laboratory, McGill University, Royal Victoria Hospital, Montreal, Quebec, Canada
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