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Belloir C, Moitrier L, Karolkowski A, Poirier N, Neiers F, Briand L. Inosine-5'-monophosphate interacts with the TAS1R3 subunit to enhance sweet taste detection. FOOD CHEMISTRY. MOLECULAR SCIENCES 2025; 10:100246. [PMID: 40034539 PMCID: PMC11872639 DOI: 10.1016/j.fochms.2025.100246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/12/2024] [Revised: 02/05/2025] [Accepted: 02/09/2025] [Indexed: 03/05/2025]
Abstract
Umami and sweet taste detection is mediated by the activation of the TAS1R1/TAS1R3 and TAS1R2/TAS1R3 receptors, respectively. TAS1R2-Venus flytrap domain (VFT) constitutes the primary ligand-binding site for most of the sweeteners whereas TAS1R1-VFT contains the orthosteric binding site for umami compounds. Inosine-5'-monophosphate (IMP), previously known to potentiate umami taste, binds to a site of TAS1R1-VFT adjacent to the L-glutamate site leading to umami synergy. However, the involvement of the TAS1R3 subunit in umami receptor-ligand interactions or in synergy with IMP has never been demonstrated. To elucidate the VFT contribution to umami and sweet detection, we expressed human TAS1R1- and TAS1R3-VFTs in bacteria. Ligand binding studies quantified by intrinsic tryptophan fluorescence revealed that both TAS1R1- and TAS1R3-VFTs are able to interact with umami compounds. Cellular assays revealed that IMP is able, like cyclamate, to modulate the response of TAS1R2/TAS1R3 and TAS1R3 alone stimulated by calcium ions. IMP also acted as an enhancer of TAS1R2/TAS1R3 when stimulated with sucralose, neotame and cyclamate. Taking together, our data demonstrated that IMP modulates sweet compound detection at the receptor level acting via the TAS1R3 subunit. This research suggests more complex receptor interactions between umami and sweet taste qualities and paves the way for development of new sweetness enhancers.
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Affiliation(s)
- Christine Belloir
- Centre des Sciences du Goût et de l'Alimentation, CNRS, INRAE, Institut Agro, Université Bourgogne Europe, F-21000 Dijon, France
| | - Lucie Moitrier
- Centre des Sciences du Goût et de l'Alimentation, CNRS, INRAE, Institut Agro, Université Bourgogne Europe, F-21000 Dijon, France
| | - Adeline Karolkowski
- Centre des Sciences du Goût et de l'Alimentation, CNRS, INRAE, Institut Agro, Université Bourgogne Europe, F-21000 Dijon, France
| | - Nicolas Poirier
- Centre des Sciences du Goût et de l'Alimentation, CNRS, INRAE, Institut Agro, Université Bourgogne Europe, F-21000 Dijon, France
| | - Fabrice Neiers
- Centre des Sciences du Goût et de l'Alimentation, CNRS, INRAE, Institut Agro, Université Bourgogne Europe, F-21000 Dijon, France
| | - Loïc Briand
- Centre des Sciences du Goût et de l'Alimentation, CNRS, INRAE, Institut Agro, Université Bourgogne Europe, F-21000 Dijon, France
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Boisen IM, Du W, Juul A, Bräuner-Osborne H, Jensen AA, Blomberg Jensen M. Loss-of-function Thr347Ala Variant in the G Protein Subunit-Α11 Causes Familial Hypocalciuric Hypercalcemia 2. J Clin Endocrinol Metab 2025; 110:1342-1349. [PMID: 38920275 DOI: 10.1210/clinem/dgae440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 05/18/2024] [Accepted: 06/24/2024] [Indexed: 06/27/2024]
Abstract
CONTEXT AND OBJECTIVES To date, only 4 loss-of-function variants in the GNA11 gene encoding the G protein subunit α11 (Gα11) leading to familial hypocalciuric hypercalcemia (FHH) 2 have been characterized. Gα11 is involved in calcium-sensing receptor (CaSR) signaling, and loss-of-function variants in GNA11 lead to reduced agonist potency at CaSR and an FHH phenotype. DESIGN AND PARTICIPANTS We have identified a family with a heterozygous GNA11 Thr347Ala variant and characterized its impact on calcium homeostasis in FHH2 patients and the signaling properties of CaSR through the Gα11-Thr347Ala variant in vitro. MAIN OUTCOME MEASURES The index patient and her family had clinical, biochemical, and genetic analyses performed. The expression levels of Gα11 and the cell-surface expression levels of CaSR in human embryonic kidney 293A Gq/11 knockout cells (ΔGq/11-HEK293A) cotransfected with CaSR and Gα11 [wild type (WT) or Thr347Ala] were determined, and the functional properties exhibited by calcium at CaSR were characterized in an inositol monophosphate (IP1) accumulation assay. RESULTS Heterozygous carriers of the GNA11 Thr347Ala variant had mild asymptomatic hypercalcemia, hypocalciuria, and inappropriately high normal PTH levels considering their elevated serum calcium levels. Whereas the variant did not impact Gα11 expression or CaSR cell surface expression levels, calcium displayed a moderately but significantly lower agonist potency at CaSR/Gα11-Thr347Ala-transfected cells compared with CaSR/Gα11-WT-transfected cells in the IP1 accumulation assay (EC50 values of 5.67 mM and 4.38 mM, respectively). CONCLUSION This identification of a novel GNA11 variant causing FHH2 substantiates the important role of Gα11 for CaSR signaling and Ca2+ homeostasis.
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Affiliation(s)
- Ida Marie Boisen
- Division of Translational Endocrinology, Department of Endocrinology and Internal Medicine, University Hospital Copenhagen, DK-2730 Herlev, Denmark
- Department of Growth and Reproduction, Copenhagen University Hospital-Rigshospitalet, DK-2100 Copenhagen, Denmark
| | - Wei Du
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Anders Juul
- Department of Growth and Reproduction, Copenhagen University Hospital-Rigshospitalet, DK-2100 Copenhagen, Denmark
- International Centre for Research and Research Training in Endocrine Disruption of Male Reproduction and Child Health, Copenhagen University Hospital-Rigshospitalet, DK-2100 Copenhagen, Denmark
| | - Hans Bräuner-Osborne
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Anders A Jensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Martin Blomberg Jensen
- Division of Translational Endocrinology, Department of Endocrinology and Internal Medicine, University Hospital Copenhagen, DK-2730 Herlev, Denmark
- Department of Clinical Medicine, University of Copenhagen, DK-2100 Copenhagen, Denmark
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Yuan M, Ma T, Fan Z, Li J, Zhang S. The calcium-sensing receptor: a comprehensive review on its role in calcium homeostasis and therapeutic implications. Am J Transl Res 2025; 17:2322-2338. [PMID: 40226019 PMCID: PMC11982861 DOI: 10.62347/qgts5711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2025] [Accepted: 03/04/2025] [Indexed: 04/15/2025]
Abstract
The calcium-sensing receptor (CaSR), a key member of the family C G protein-coupled receptors (GPCRs), plays a crucial role in regulating calcium homeostasis and parathyroid hormone (PTH) secretion. It responds to various physiological ligands, including calcium ions and amino acids, activating multiple signaling pathways through interactions with different G proteins and β-arrestin. This review focuses on the structural features of CaSR, emphasizing recent advances in understanding its activation mechanisms via agonists and allosteric modulators. CaSR holds significant therapeutic potential, particularly in treating calcitropic disorders such as hyperparathyroidism and hypoparathyroidism. Current pharmacological agents, including calcimimetics such as cinacalcet and etelcalcetide, have proven effective in managing secondary hyperparathyroidism (SHPT); however, they are associated with side effects such as hypocalcemia. Emerging investigational drugs, including palopegteriparatide and other small molecules, show promise in addressing various calcium-related conditions. Despite challenges that have led to the discontinuation of some drug developments, ongoing research is focused on refining CaSR-targeted therapies to improve efficacy, reduce adverse effects, and enhance patient outcomes.
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Affiliation(s)
- Ming Yuan
- Bioland Laboratory (Guangzhou Regenerative Medicine and Health Guangdong Laboratory)Guangzhou 510005, Guangdong, China
- Cellular Signaling Laboratory, International Research Center for Sensory Biology and Technology of MOST, Key Laboratory of Molecular Biophysics of MOE, College of Life Science and Technology, Huazhong University of Science and TechnologyWuhan 430074, Hubei, China
| | - Tianrui Ma
- Bioland Laboratory (Guangzhou Regenerative Medicine and Health Guangdong Laboratory)Guangzhou 510005, Guangdong, China
| | - Zhiran Fan
- Bioland Laboratory (Guangzhou Regenerative Medicine and Health Guangdong Laboratory)Guangzhou 510005, Guangdong, China
| | - Jing Li
- Bioland Laboratory (Guangzhou Regenerative Medicine and Health Guangdong Laboratory)Guangzhou 510005, Guangdong, China
| | - Shenglan Zhang
- Bioland Laboratory (Guangzhou Regenerative Medicine and Health Guangdong Laboratory)Guangzhou 510005, Guangdong, China
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4
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Belloir C, Gautier A, Karolkowski A, Delompré T, Jeannin M, Moitrier L, Neiers F, Briand L. Optimized vector for functional expression of the human bitter taste receptor TAS2R14 in HEK293 cells. Protein Expr Purif 2025; 227:106643. [PMID: 39667443 DOI: 10.1016/j.pep.2024.106643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2024] [Revised: 12/06/2024] [Accepted: 12/07/2024] [Indexed: 12/14/2024]
Abstract
Bitter is one of the five basic taste qualities, along with salty, sour, sweet and umami, used by mammals to access the quality of their food and orient their eating behaviour. Bitter taste detection prevents the ingestion of food potentially contaminated by bitter-tasting toxins. Bitter taste perception is mediated by a family of G protein-coupled receptors (GPCRs) called TAS2Rs. Humans possess 25 TAS2Rs (human type II taste receptors), enabling the detection of thousands of chemically diverse bitter compounds. The identification of agonists/antagonists and molecular mechanisms that govern receptor-ligand interaction has been primarily achieved through functional expression of TAS2Rs in heterologous cells. However, TAS2R receptors, like many other GPCRs, suffer from marginal cell surface expression. In this study, we compared the functionality of 9 engineered chimeric receptors, focusing our experiments on TAS2R14, a broadly tuned receptor that recognizes over 151 identified compounds. Among the different tested signal peptides, rat somatostatin receptor subtype 3 results in higher potency of aristolochic acid-induced calcium signalling than other tested export tags, such as bovine rhodopsin, murine Igκ-chain or human mGluR5. The addition of a MAX sequence enhances both TAS2R14 potency and efficacy. We also confirm that the FLAG epitope, when located at the C-terminal, interferes less with the TAS2R14 functionality, enabling reliable evaluation of this receptor at the cell surface using immunohistochemistry. Finally, these observations are also confirmed for TAS2R14 and TAS1R2/TAS1R3 (the sweet taste receptor) stimulated by 12 bitter compounds and by sucralose and neotame, respectively.
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Affiliation(s)
- Christine Belloir
- Centre des Sciences Du Goût et de l'Alimentation, CNRS, INRAE, Institut Agro, Université de Bourgogne, F-21000, France.
| | - Adèle Gautier
- Centre des Sciences Du Goût et de l'Alimentation, CNRS, INRAE, Institut Agro, Université de Bourgogne, F-21000, France.
| | - Adeline Karolkowski
- Centre des Sciences Du Goût et de l'Alimentation, CNRS, INRAE, Institut Agro, Université de Bourgogne, F-21000, France.
| | - Thomas Delompré
- Centre des Sciences Du Goût et de l'Alimentation, CNRS, INRAE, Institut Agro, Université de Bourgogne, F-21000, France.
| | - Mathilde Jeannin
- Centre des Sciences Du Goût et de l'Alimentation, CNRS, INRAE, Institut Agro, Université de Bourgogne, F-21000, France.
| | - Lucie Moitrier
- Centre des Sciences Du Goût et de l'Alimentation, CNRS, INRAE, Institut Agro, Université de Bourgogne, F-21000, France.
| | - Fabrice Neiers
- Centre des Sciences Du Goût et de l'Alimentation, CNRS, INRAE, Institut Agro, Université de Bourgogne, F-21000, France.
| | - Loïc Briand
- Centre des Sciences Du Goût et de l'Alimentation, CNRS, INRAE, Institut Agro, Université de Bourgogne, F-21000, France.
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Du W, Rahman SN, Barker E, Bräuner-Osborne H, Mathiesen JM, Ward DT, Jensen AA. Detailed functional characterization of four nanobodies as positive allosteric modulators of the human calcium-sensing receptor. Biochem Pharmacol 2025; 231:116619. [PMID: 39522703 DOI: 10.1016/j.bcp.2024.116619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2024] [Revised: 10/02/2024] [Accepted: 11/07/2024] [Indexed: 11/16/2024]
Abstract
The calcium-sensing receptor (CaSR) plays a key role in calcium homeostasis, and small-molecule and peptide positive allosteric modulators (PAMs) of CaSR, so-called calcimimetics, are used in the treatment of hyperparathyroidism and hypocalcemic disorders. In this study, four monovalent nanobodies - representing four distinct nanobody families with CaSR PAM activity - were subjected to elaborate pharmacological profiling at the receptor. While Nb5 displayed negligible PAM activity at CaSR in all assays, Nb4, Nb10 and Nb45 all potently potentiated Ca2+-evoked signalling through a myc epitope-tagged CaSR expressed in HEK293 or HEK293T cells in Gαq and Gαi1 protein activation assays and in a Ca2+/Fluo-4 assay. Nb4 and Nb10 also displayed comparable PAM properties at a stable CaSR-HEK293 cell line in a Ca2+/Fura-2 imaging assay, but surprisingly Nb45 was completely inactive at this cell line in both the Ca2+/Fura-2 and Ca2+/Fluo-4 assays. Investigations into this binary difference in Nb45 activity revealed that the nanobody only possesses modulatory activity at CaSRs tagged N-terminally with various epitopes (myc, HA, Flag-SNAP), whereas it is inactive at the untagged wild-type receptor. In conclusion, overall each of the four nanobodies exhibit similar CaSR PAM properties in a range of assays, and thus none of them display pathway bias as modulators. However, of the four nanobodies Nb4 and Nb10 would be applicable as pharmacological tools for the wild-type CaSR, whereas the complete inactivity of Nb45 at the untagged CaSR serves as an reminder that epitope-tagging of a receptor, even if deemed functionally silent, can have profound implications for ligand discovery efforts.
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Affiliation(s)
- Wei Du
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen Ø, Denmark
| | - Sabrina N Rahman
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen Ø, Denmark
| | - Eleanor Barker
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom
| | - Hans Bräuner-Osborne
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen Ø, Denmark
| | - Jesper M Mathiesen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen Ø, Denmark
| | - Donald T Ward
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom
| | - Anders A Jensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen Ø, Denmark.
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6
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Li H, Li X, Sun Y, Zhi Z, Song L, Li M, Feng Y, Zhang Z, Liu Y, Chen Y, Zhao F, Zhu T. The Role of Ion Channels in Pulmonary Hypertension: A Review. Pulm Circ 2025; 15:e70050. [PMID: 39958971 PMCID: PMC11830494 DOI: 10.1002/pul2.70050] [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: 04/22/2024] [Revised: 08/16/2024] [Accepted: 01/31/2025] [Indexed: 02/18/2025] Open
Abstract
Pulmonary hypertension (PH) constitutes a critical challenge in cardiopulmonary medicine with a pathogenesis that is multifaceted and intricate. Ion channels, crucial determinants of cellular electrochemical gradient modulation, have emerged as significant participants in the pathophysiological progression of PH. These channels, abundant on the membranes of pulmonary artery smooth muscle cells (PASMCs) and pulmonary artery endothelial cells (PAECs), pivotally navigate the nuanced interplay of cell proliferation, migration, and endothelial function, each vital to the pulmonary vascular remodeling (PVR) hallmark of PH. Our review delves into the mechanistic insights of potassium, calcium, magnesium, zinc, and chloride ion channels in relation to their involvement in PH. It not only emphasizes the notable advances and discoveries that cast these ion channels as underlying factors in the etiology and exacerbation of PH but also highlights their potential as innovative therapeutic targets.
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Affiliation(s)
- Han‐Fei Li
- College of PharmacyXinxiang Medical UniversityXinxiangChina
- Henan International Joint Laboratory of Cardiovascular Remodeling and Drug InterventionXinxiangChina
| | - Xin‐Yao Li
- College of PharmacyXinxiang Medical UniversityXinxiangChina
- Henan International Joint Laboratory of Cardiovascular Remodeling and Drug InterventionXinxiangChina
| | - Yu‐Qing Sun
- College of PharmacyXinxiang Medical UniversityXinxiangChina
- Henan International Joint Laboratory of Cardiovascular Remodeling and Drug InterventionXinxiangChina
| | - Ze‐Ying Zhi
- College of PharmacyXinxiang Medical UniversityXinxiangChina
- Henan International Joint Laboratory of Cardiovascular Remodeling and Drug InterventionXinxiangChina
| | - Liao‐Fan Song
- College of PharmacyXinxiang Medical UniversityXinxiangChina
- Henan International Joint Laboratory of Cardiovascular Remodeling and Drug InterventionXinxiangChina
| | - Meng Li
- College of PharmacyXinxiang Medical UniversityXinxiangChina
- Henan International Joint Laboratory of Cardiovascular Remodeling and Drug InterventionXinxiangChina
| | - Yi‐Ming Feng
- College of PharmacyXinxiang Medical UniversityXinxiangChina
- Henan International Joint Laboratory of Cardiovascular Remodeling and Drug InterventionXinxiangChina
| | - Zhi‐Hao Zhang
- College of PharmacyXinxiang Medical UniversityXinxiangChina
- Henan International Joint Laboratory of Cardiovascular Remodeling and Drug InterventionXinxiangChina
| | - Yan‐Feng Liu
- College of PharmacyXinxiang Medical UniversityXinxiangChina
- Henan International Joint Laboratory of Cardiovascular Remodeling and Drug InterventionXinxiangChina
| | - Yu‐Jing Chen
- College of PharmacyXinxiang Medical UniversityXinxiangChina
- Henan International Joint Laboratory of Cardiovascular Remodeling and Drug InterventionXinxiangChina
| | - Fan‐Rong Zhao
- College of PharmacyXinxiang Medical UniversityXinxiangChina
- Henan International Joint Laboratory of Cardiovascular Remodeling and Drug InterventionXinxiangChina
| | - Tian‐Tian Zhu
- College of PharmacyXinxiang Medical UniversityXinxiangChina
- Henan International Joint Laboratory of Cardiovascular Remodeling and Drug InterventionXinxiangChina
- Department of PharmacyThe First Affiliated Hospital of Xinxiang Medical UniversityXinxiangChina
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7
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Du W, Boisen IM, Rahman SN, Poulsen NN, Mathiesen JM, Blomberg Jensen M, Bräuner-Osborne H, Jensen AA. Heterogenous Origins of Calcium Homeostasis Disorders Arising from Five Heterozygous Calcium-Sensing Receptor Variants. J Clin Endocrinol Metab 2024:dgae735. [PMID: 39413244 DOI: 10.1210/clinem/dgae735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2024] [Revised: 09/27/2024] [Accepted: 10/15/2024] [Indexed: 10/18/2024]
Abstract
CONTEXT AND OBJECTIVES The human calcium-sensing receptor (CaSR) plays a key role in calcium homeostasis, and most identified CASR variants are associated with hypercalcemic and hypocalcemic disorders. Here we characterized the pharmacological implications of five heterozygous CASR variants from individuals with familial hypocalciuric hypercalcemia 1 [FHH1: Y63C, I81T, Q459R, W818stop] or autosomal dominant hypocalcemia 1 [ADH1: R955stop]. METHODS Total and cell surface expression levels of wild-type (WT) and variant CaSRs expressed in human embryonic kidney 293T (HEK293T) cells were determined using ELISA, and the pharmacological properties of the receptors were delineated in two functional assays. RESULTS The Y63C and I81T variations in the extracellular domain (ECD) of CaSR yielded markedly reduced cell surface expression and Ca2+ responsiveness, while Q459R displayed WT-like expression and functional properties. Truncation of the 7-transmembrane domain (7TMD) in W818stop eliminated cell surface expression, whereas R955stop in the intracellular carboxy-terminal yielded modestly increased surface expression and Ca2+ potency compared with WT CaSR. Interestingly, the effectiveness of positive allosteric modulators (PAMs) at the variants varied. Ca2+-mediated signaling through Y63C and I81T was significantly augmented by 7TMD-binding PAMs (NPS R-568 and Evocalcet) but not by ECD-binding PAMs (Etelcalcetide and Nb4), whereas signaling through Q459R and R955stop were robustly potentiated by all four PAMs. CONCLUSIONS While the molecular phenotypes exhibited by the five CaSR variants concord with the clinical phenotypes in individuals harboring them, CASR variant-induced calcium homeostasis disorders clearly arise from diverse molecular origins, and the effectiveness of calcimimetics in these disorders could differ depending on the specific variants.
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Affiliation(s)
- Wei Du
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2100 Copenhagen Ø, Denmark
| | - Ida Marie Boisen
- Division of Translational Endocrinology, Department of Endocrinology and Internal Medicine, University Hospital Copenhagen, Herlev-Gentofte, DK-2730 Herlev, Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Sabrina N Rahman
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2100 Copenhagen Ø, Denmark
| | - Nadia Nicholine Poulsen
- Division of Translational Endocrinology, Department of Endocrinology and Internal Medicine, University Hospital Copenhagen, Herlev-Gentofte, DK-2730 Herlev, Denmark
| | - Jesper M Mathiesen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2100 Copenhagen Ø, Denmark
| | - Martin Blomberg Jensen
- Division of Translational Endocrinology, Department of Endocrinology and Internal Medicine, University Hospital Copenhagen, Herlev-Gentofte, DK-2730 Herlev, Denmark
| | - Hans Bräuner-Osborne
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2100 Copenhagen Ø, Denmark
| | - Anders A Jensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2100 Copenhagen Ø, Denmark
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8
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Belkacemi K, Rondard P, Pin JP, Prézeau L. Heterodimers Revolutionize the Field of Metabotropic Glutamate Receptors. Neuroscience 2024:S0306-4522(24)00270-7. [PMID: 38936459 DOI: 10.1016/j.neuroscience.2024.06.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Revised: 06/13/2024] [Accepted: 06/17/2024] [Indexed: 06/29/2024]
Abstract
Identified 40 years ago, the metabotropic glutamate (mGlu) receptors play key roles in modulating many synapses in the brain, and are still considered as important drug targets to treat various brain diseases. Eight genes encoding mGlu subunits have been identified. They code for complex receptors composed of a large extracellular domain where glutamate binds, connected to a G protein activating membrane domain. They are covalently linked dimers, a quaternary structure needed for their activation by glutamate. For many years they have only been considered as homodimers, then limiting the number of mGlu receptors to 8 subtypes composed of twice the same subunit. Twelve years ago, mGlu subunits were shown to also form heterodimers with specific subunits combinations, increasing the family up to 19 different potential dimeric receptors. Since then, a number of studies brought evidence for the existence of such heterodimers in the brain, through various approaches. Structural and molecular dynamic studies helped understand their peculiar activation process. The present review summarizes the approaches used to study their activation process and their pharmacological properties and to demonstrate their existence in vivo. We will highlight how the existence of mGlu heterodimers revolutionizes the mGlu receptor field, opening new possibilities for therapeutic intervention for brain diseases. As illustrated by the number of possible mGlu heterodimers, this study will highlight the need for further research to fully understand their role in physiological and pathological conditions, and to develop more specific therapeutic tools.
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Affiliation(s)
- Kawthar Belkacemi
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, Inserm, Montpellier, France
| | - Philippe Rondard
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, Inserm, Montpellier, France
| | - Jean-Philippe Pin
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, Inserm, Montpellier, France.
| | - Laurent Prézeau
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, Inserm, Montpellier, France.
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9
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Ma S, Yin X, Pin JP, Rondard P, Yi P, Liu J. Absence of calcium-sensing receptor basal activity due to inter-subunit disulfide bridges. Commun Biol 2024; 7:501. [PMID: 38664468 PMCID: PMC11045811 DOI: 10.1038/s42003-024-06189-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 04/12/2024] [Indexed: 04/28/2024] Open
Abstract
G protein-coupled receptors naturally oscillate between inactive and active states, often resulting in receptor constitutive activity with important physiological consequences. Among the class C G protein-coupled receptors that typically sense amino-acids and their derivatives, the calcium sensing receptor (CaSR) tightly controls blood calcium levels. Its constitutive activity has not yet been studied. Here, we demonstrate the importance of the inter-subunit disulfide bridges in maintaining the inactive state of CaSR, resulting in undetectable constitutive activity, unlike the other class C receptors. Deletion of these disulfide bridges results in strong constitutive activity that is abolished by mutations preventing amino acid binding. It shows that this inter-subunit disulfide link is necessary to limit the agonist effect of amino acids on CaSR. Furthermore, human genetic mutations deleting these bridges and associated with hypocalcemia result in elevated CaSR constitutive activity. These results highlight the physiological importance of fine tuning the constitutive activity of G protein-coupled receptors.
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Affiliation(s)
- Shumin Ma
- Cellular Signaling Laboratory, International Research Center for Sensory Biology and Technology of MOST, Key Laboratory of Molecular Biophysics of MOE, and College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Xueliang Yin
- Cellular Signaling Laboratory, International Research Center for Sensory Biology and Technology of MOST, Key Laboratory of Molecular Biophysics of MOE, and College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Jean-Philippe Pin
- Institut de Génomique Fonctionnelle (IGF), Université de Montpellier, CNRS, INSERM, Montpellier, Cedex 5, France
| | - Philippe Rondard
- Institut de Génomique Fonctionnelle (IGF), Université de Montpellier, CNRS, INSERM, Montpellier, Cedex 5, France.
| | - Ping Yi
- Cellular Signaling Laboratory, International Research Center for Sensory Biology and Technology of MOST, Key Laboratory of Molecular Biophysics of MOE, and College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, China.
| | - Jianfeng Liu
- Cellular Signaling Laboratory, International Research Center for Sensory Biology and Technology of MOST, Key Laboratory of Molecular Biophysics of MOE, and College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, China.
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10
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Schüß C, Vu O, Mishra NM, Tough IR, Du Y, Stichel J, Cox HM, Weaver CD, Meiler J, Emmitte KA, Beck-Sickinger AG. Structure-Activity Relationship Study of the High-Affinity Neuropeptide Y 4 Receptor Positive Allosteric Modulator VU0506013. J Med Chem 2023. [PMID: 37339079 DOI: 10.1021/acs.jmedchem.3c00383] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/22/2023]
Abstract
Positive allosteric modulators targeting the Y4 receptor (Y4R), a G protein-coupled receptor (GPCR) involved in the regulation of satiety, offer great potential in anti-obesity research. In this study, we selected 603 compounds by using quantitative structure-activity relationship (QSAR) models and tested them in high-throughput screening (HTS). Here, the novel positive allosteric modulator (PAM) VU0506013 was identified, which exhibits nanomolar affinity and pronounced selectivity toward the Y4R in engineered cell lines and mouse descending colon mucosa natively expressing the Y4R. Based on this lead structure, we conducted a systematic SAR study in two regions of the scaffold and presented a series of 27 analogues with modifications in the N- and C-terminal heterocycles of the molecule to obtain insight into functionally relevant positions. By mutagenesis and computational docking, we present a potential binding mode of VU0506013 in the transmembrane core of the Y4R. VU0506013 presents a promising scaffold for developing in vivo tools to move toward anti-obesity drug research focused on the Y4R.
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Affiliation(s)
- Corinna Schüß
- Institute of Biochemistry, Leipzig University, Leipzig 04103, Germany
| | - Oanh Vu
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Nigam M Mishra
- Department of Pharmaceutical Sciences, UNT System College of Pharmacy, University of North Texas Health Science Center, Fort Worth, Texas 76107, United States
| | - Iain R Tough
- King's College London, Wolfson Centre for Age-Related Diseases, Institute of Psychiatry, Psychology & Neuroscience, London SE1 1UL, U.K
| | - Yu Du
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Jan Stichel
- Institute of Biochemistry, Leipzig University, Leipzig 04103, Germany
| | - Helen M Cox
- King's College London, Wolfson Centre for Age-Related Diseases, Institute of Psychiatry, Psychology & Neuroscience, London SE1 1UL, U.K
| | - C David Weaver
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, United States
- Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Jens Meiler
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, United States
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232, United States
- Institute for Drug Discovery, Leipzig University, Leipzig 04103, Germany
| | - Kyle A Emmitte
- Department of Pharmaceutical Sciences, UNT System College of Pharmacy, University of North Texas Health Science Center, Fort Worth, Texas 76107, United States
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11
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Liu H, Li Y, Gao Y. Asymmetric activation of class C GPCRs. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2023; 195:77-87. [PMID: 36707156 DOI: 10.1016/bs.pmbts.2022.06.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Class C G-protein-coupled receptors (GPCRs) comprise a unique GPCR subfamily with large ligand-binding extracellular domains and function as obligate dimers. The recently resolved cryo-EM structures of full-length GABAB, CaSR, and mGlus have revealed that these receptors are activated in an asymmetric manner, leading to G-protein-coupling on one protomer within the receptor dimer. In this review we discuss the mechanisms of asymmetric activation in class C GPCRs and the unique mode of interaction with the inhibitory Gi protein. Upon activation, the two seven-transmembrane domains (7TMs) of class C GPCRs rearrange to form a conserved asymmetric TM6-TM6 interface. In contrast to class A and B GPCRs, G-protein coupling does not involve the cytoplasmic opening of TM6, but is facilitated through the coordination of intracellular loops. Furthermore, positive and negative allosteric modulators (PAMs and NAMs) adopt distinct conformations to regulate the activity of class C GPCRs. Taken together, these recent findings on the mechanism of asymmetric activation of class C GPCRs highlight a novel mechanism of G protein activation and provide new insights into the design of therapeutics targeting these receptors.
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Affiliation(s)
- Hongnan Liu
- Department of Cardiology of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China; Liangzhu Laboratory, Zhejiang University Medical Center, Hangzhou, China
| | - Yanjun Li
- Department of Cardiology of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China; Liangzhu Laboratory, Zhejiang University Medical Center, Hangzhou, China
| | - Yang Gao
- Department of Cardiology of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China; Liangzhu Laboratory, Zhejiang University Medical Center, Hangzhou, China; Key Laboratory of Cardiovascular Intervention and Regenerative Medicine of Zhejiang Province, Hangzhou, China.
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12
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Gorvin CM. Recent advances in calcium-sensing receptor structures and signaling pathways. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2023; 195:121-135. [PMID: 36707151 DOI: 10.1016/bs.pmbts.2022.06.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The calcium-sensing receptor (CaSR) is a class C GPCR that has a fundamental role in extracellular calcium homeostasis by regulating parathyroid hormone release and urinary calcium excretion. Germline mutations in the receptor cause disorders of calcium homeostasis and studies of the functional effects of these mutations has facilitated understanding of CaSR signaling and how allosteric modulators affect these responses. In the past year, five cryo-EM structures of the near full-length CaSR have been published, demonstrating how agonist-binding transmits changes in the CaSR extracellular domain to the transmembrane region to activate G proteins, and how allosteric modulators affect these structural dynamics. Additionally, several recent studies have identified CaSR interacting proteins that regulate CaSR signaling and trafficking and contribute to understanding how the receptor achieves rapid and diverse physiological responses.
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Affiliation(s)
- Caroline M Gorvin
- Centre of Membrane Proteins and Receptors (COMPARE), Universities of Birmingham and Nottingham, Birmingham, United Kingdom; Institute of Metabolism and Systems Research (IMSR) and Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, University of Birmingham, Birmingham, United Kingdom.
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13
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Sato H, Murakami S, Horii Y, Nishimura G, Iwai R, Goto M, Takahashi N. Upacicalcet Is a Novel Secondary Hyperparathyroidism Drug that Targets the Amino Acid Binding Site of Calcium-Sensing Receptor . Mol Pharmacol 2022; 102:183-195. [PMID: 36122913 DOI: 10.1124/molpharm.122.000522] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Accepted: 07/14/2022] [Indexed: 02/14/2025] Open
Abstract
The human calcium-sensing receptor (CaSR) is a G protein-coupled receptor that maintains extracellular Ca2+ homeostasis by regulating the secretion of parathyroid hormone. Upacicalcet is a novel positive allosteric modulator of CaSR that is used for the treatment of secondary hyperparathyroidism. In the present study, to clarify the binding site of upacicalcet to CaSR, we conducted binding studies and agonistic activity studies in HEK-293T cells expressing human CaSR (intact and mutant) and an in silico docking-simulation analysis. As a result, upacicalcet competed with L-tryptophan and was thought to affect the amino acid binding site. In addition, the effects of substitutions at the amino acid binding site on the binding abilities to upacicalcet as well as the effects on receptor function as measured using inositol-1 monophosphate accumulation were examined. Upacicalcet interacted with several CaSR residues that constitute the amino acid binding site. Based on these results, we performed an in silico analysis and obtained a binding mode, consistent with the in vitro study results. Our study revealed that upacicalcet is a novel secondary hyperparathyroidism drug that targets the amino acid binding site of CaSR. Upacicalcet is expected to become a new treatment option for secondary hyperparathyroidism because the binding site differs from that of conventional drugs; consequently, it may be effective for patients who are not sensitive to conventional drugs, and it may have a superior safety profile. SIGNIFICANCE STATEMENT: Upacicalcet interacts with several residues that constitute the amino acid binding site of the calcium-sensing receptor (CaSR) and shows a potent positive allosteric activity. This mechanism differs from those of conventional drugs. Therefore, upacicalcet can be regarded as a novel secondary hyperparathyroidism drug that acts on the amino acid binding site of CaSR.
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Affiliation(s)
- Hirofumi Sato
- Pharmaceuticals Research Laboratories, Sanwa Kagaku Kenkyusho Co., Ltd., Mie, Japan
| | - Sei Murakami
- Pharmaceuticals Research Laboratories, Sanwa Kagaku Kenkyusho Co., Ltd., Mie, Japan
| | - Yusuke Horii
- Pharmaceuticals Research Laboratories, Sanwa Kagaku Kenkyusho Co., Ltd., Mie, Japan
| | - Go Nishimura
- Pharmaceuticals Research Laboratories, Sanwa Kagaku Kenkyusho Co., Ltd., Mie, Japan
| | - Ryosuke Iwai
- Pharmaceuticals Research Laboratories, Sanwa Kagaku Kenkyusho Co., Ltd., Mie, Japan
| | - Moritaka Goto
- Pharmaceuticals Research Laboratories, Sanwa Kagaku Kenkyusho Co., Ltd., Mie, Japan
| | - Naoki Takahashi
- Pharmaceuticals Research Laboratories, Sanwa Kagaku Kenkyusho Co., Ltd., Mie, Japan
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14
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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: 3] [Impact Index Per Article: 1.0] [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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15
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Xu R, Cheng P, Meng K, Li L, Jiao M, Zhao X, Jia P, Zheng X, Xiao C. Extracellular domain of human calcium sensing receptor immobilized to silica beads as biomaterial: a rapid chromatographic method for recognizing ligands from complex matrix ‘Shuangdan’. J Chromatogr B Analyt Technol Biomed Life Sci 2022; 1208:123409. [DOI: 10.1016/j.jchromb.2022.123409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 08/03/2022] [Accepted: 08/04/2022] [Indexed: 10/15/2022]
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16
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Chen CJ, Jiang C, Yuan J, Chen M, Cuyler J, Xie XQ, Feng Z. How Do Modulators Affect the Orthosteric and Allosteric Binding Pockets? ACS Chem Neurosci 2022; 13:959-977. [PMID: 35298129 PMCID: PMC10496248 DOI: 10.1021/acschemneuro.1c00749] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Allosteric modulators (AMs) that bind allosteric sites can exhibit greater selectivity than the orthosteric ligands and can either enhance agonist-induced receptor activity (termed positive allosteric modulator or PAM), inhibit agonist-induced activity (negative AM or NAM), or have no effect on activity (silent AM or SAM). Until now, it is not clear what the exact effects of AMs are on the orthosteric active site or the allosteric binding pocket(s). In the present work, we collected both the three-dimensional (3D) structures of receptor-orthosteric ligand and receptor-orthosteric ligand-AM complexes of a specific target protein. Using our novel algorithm toolset, molecular complex characterizing system (MCCS), we were able to quantify the key residues in both the orthosteric and allosteric binding sites along with potential changes of the binding pockets. After analyzing 21 pairs of 3D crystal or cryo-electron microscopy (cryo-EM) complexes, including 4 pairs of GPCRs, 5 pairs of ion channels, 11 pairs of enzymes, and 1 pair of transcription factors, we found that the binding of AMs had little impact on both the orthosteric and allosteric binding pockets. In return, given the accurately predicted allosteric binding pocket(s) of a drug target of medicinal interest, we can confidently conduct the virtual screening or lead optimization without concern that the huge conformational change of the pocket could lead to the low accuracy of virtual screening.
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Affiliation(s)
- Chih-Jung Chen
- Department of Pharmaceutical Sciences and Computational Chemical Genomics Screening Center, School of Pharmacy, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
- National Center of Excellence for Computational Drug Abuse Research, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
| | - Chen Jiang
- Department of Pharmaceutical Sciences and Computational Chemical Genomics Screening Center, School of Pharmacy, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
- National Center of Excellence for Computational Drug Abuse Research, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
| | - Jiayi Yuan
- Department of Pharmaceutical Sciences and Computational Chemical Genomics Screening Center, School of Pharmacy, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
- National Center of Excellence for Computational Drug Abuse Research, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
| | - Maozi Chen
- Department of Pharmaceutical Sciences and Computational Chemical Genomics Screening Center, School of Pharmacy, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
- National Center of Excellence for Computational Drug Abuse Research, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
| | - Jacob Cuyler
- Department of Pharmaceutical Sciences and Computational Chemical Genomics Screening Center, School of Pharmacy, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
- National Center of Excellence for Computational Drug Abuse Research, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
| | - Xiang-Qun Xie
- Department of Pharmaceutical Sciences and Computational Chemical Genomics Screening Center, School of Pharmacy, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
- National Center of Excellence for Computational Drug Abuse Research, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
- Drug Discovery Institute, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
- Departments of Computational Biology and Structural Biology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
| | - Zhiwei Feng
- Department of Pharmaceutical Sciences and Computational Chemical Genomics Screening Center, School of Pharmacy, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
- National Center of Excellence for Computational Drug Abuse Research, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
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17
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Symmetric activation and modulation of the human calcium-sensing receptor. Proc Natl Acad Sci U S A 2021; 118:2115849118. [PMID: 34916296 DOI: 10.1073/pnas.2115849118] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/10/2021] [Indexed: 01/14/2023] Open
Abstract
The human extracellular calcium-sensing (CaS) receptor controls plasma Ca2+ levels and contributes to nutrient-dependent maintenance and metabolism of diverse organs. Allosteric modulation of the CaS receptor corrects disorders of calcium homeostasis. Here, we report the cryogenic-electron microscopy reconstructions of a near-full-length CaS receptor in the absence and presence of allosteric modulators. Activation of the homodimeric CaS receptor requires a break in the transmembrane 6 (TM6) helix of each subunit, which facilitates the formation of a TM6-mediated homodimer interface and expansion of homodimer interactions. This transformation in TM6 occurs without a positive allosteric modulator. Two modulators with opposite functional roles bind to overlapping sites within the transmembrane domain through common interactions, acting to stabilize distinct rotamer conformations of key residues on the TM6 helix. The positive modulator reinforces TM6 distortion and maximizes subunit contact to enhance receptor activity, while the negative modulator strengthens an intact TM6 to dampen receptor function. In both active and inactive states, the receptor displays symmetrical transmembrane conformations that are consistent with its homodimeric assembly.
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18
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Biophysical and functional characterization of the human TAS1R2 sweet taste receptor overexpressed in a HEK293S inducible cell line. Sci Rep 2021; 11:22238. [PMID: 34782704 PMCID: PMC8593021 DOI: 10.1038/s41598-021-01731-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 11/01/2021] [Indexed: 01/02/2023] Open
Abstract
Sweet taste perception is mediated by a heterodimeric receptor formed by the assembly of the TAS1R2 and TAS1R3 subunits. TAS1R2 and TAS1R3 are class C G-protein-coupled receptors whose members share a common topology, including a large extracellular N-terminal domain (NTD) linked to a seven transmembrane domain (TMD) by a cysteine-rich domain. TAS1R2-NTD contains the primary binding site for sweet compounds, including natural sugars and high-potency sweeteners, whereas the TAS1R2-TMD has been shown to bind a limited number of sweet tasting compounds. To understand the molecular mechanisms governing receptor–ligand interactions, we overexpressed the human TAS1R2 (hTAS1R2) in a stable tetracycline-inducible HEK293S cell line and purified the detergent-solubilized receptor. Circular dichroism spectroscopic studies revealed that hTAS1R2 was properly folded with evidence of secondary structures. Using size exclusion chromatography coupled to light scattering, we found that the hTAS1R2 subunit is a dimer. Ligand binding properties were quantified by intrinsic tryptophan fluorescence. Due to technical limitations, natural sugars have not been tested. However, we showed that hTAS1R2 is capable of binding high potency sweeteners with Kd values that are in agreement with physiological detection. This study offers a new experimental strategy to identify new sweeteners or taste modulators that act on the hTAS1R2 and is a prerequisite for structural query and biophysical studies.
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19
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Asymmetric activation of the calcium-sensing receptor homodimer. Nature 2021; 595:455-459. [PMID: 34194040 DOI: 10.1038/s41586-021-03691-0] [Citation(s) in RCA: 87] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 06/03/2021] [Indexed: 12/21/2022]
Abstract
The calcium-sensing receptor (CaSR), a cell-surface sensor for Ca2+, is the master regulator of calcium homeostasis in humans and is the target of calcimimetic drugs for the treatment of parathyroid disorders1. CaSR is a family C G-protein-coupled receptor2 that functions as an obligate homodimer, with each protomer composed of a Ca2+-binding extracellular domain and a seven-transmembrane-helix domain (7TM) that activates heterotrimeric G proteins. Here we present cryo-electron microscopy structures of near-full-length human CaSR in inactive or active states bound to Ca2+ and various calcilytic or calcimimetic drug molecules. We show that, upon activation, the CaSR homodimer adopts an asymmetric 7TM configuration that primes one protomer for G-protein coupling. This asymmetry is stabilized by 7TM-targeting calcimimetic drugs adopting distinctly different poses in the two protomers, whereas the binding of a calcilytic drug locks CaSR 7TMs in an inactive symmetric configuration. These results provide a detailed structural framework for CaSR activation and the rational design of therapeutics targeting this receptor.
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20
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Abstract
RORγt is a nuclear receptor associated with several diseases. Various synthetic ligands have been developed that target the canonical orthosteric or a second, allosteric pocket of RORγt. We show that orthosteric and allosteric ligands can simultaneously bind to RORγt and that their potency is positively influenced by the other ligand, a phenomenon called cooperative dual ligand binding. The mechanism behind cooperative binding in proteins is poorly understood, primarily due to the lack of structural data. We solved 12 crystal structures of RORγt, simultaneously bound to various orthosteric and allosteric ligands. In combination with molecular dynamics, we reveal a mechanism responsible for the cooperative binding behavior. Our comprehensive structural studies provide unique insights into how cooperative binding occurs in proteins. Cooperative ligand binding is an important phenomenon in biological systems where ligand binding influences the binding of another ligand at an alternative site of the protein via an intramolecular network of interactions. The underlying mechanisms behind cooperative binding remain poorly understood, primarily due to the lack of structural data of these ternary complexes. Using time-resolved fluorescence resonance energy transfer (TR-FRET) studies, we show that cooperative ligand binding occurs for RORγt, a nuclear receptor associated with the pathogenesis of autoimmune diseases. To provide the crucial structural insights, we solved 12 crystal structures of RORγt simultaneously bound to various orthosteric and allosteric ligands. The presence of the orthosteric ligand induces a clamping motion of the allosteric pocket via helices 4 to 5. Additional molecular dynamics simulations revealed the unusual mechanism behind this clamping motion, with Ala355 shifting between helix 4 and 5. The orthosteric RORγt agonists regulate the conformation of Ala355, thereby stabilizing the conformation of the allosteric pocket and cooperatively enhancing the affinity of the allosteric inverse agonists.
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21
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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: 38] [Impact Index Per Article: 9.5] [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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22
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Structural Mechanism of Cooperative Regulation of Calcium-Sensing Receptor-Mediated Cellular Signaling. CURRENT OPINION IN PHYSIOLOGY 2020; 17:269-277. [PMID: 33709045 DOI: 10.1016/j.cophys.2020.08.020] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Calcaium sensing receptors (CaSRs) play a central role in regulating extracellular calcium (Ca2+) homeostasis and many (patho)physiological processes. This regulation is primarily orchestrated in response to extracellular stimuli via the extracellular domain (ECD). This paper first reviews the modeled structure of the CaSR ECD and the prediction and investigation of the Ca2+ and amino acid binding sites. Several recently solved X-ray structures are then compared to support a proposed CaSR activation model involving functional cooperativity. The review also discusses recent implications for drug development. These studies provide new insights into the molecular basis of diseases and the design of therapeutic agents that target CaSR and other family C G protein-coupled receptors (cGPCRs).
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23
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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: 59] [Impact Index Per Article: 11.8] [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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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: 2.2] [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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25
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Boisen IM, Mos I, Lerche-Black EM, Juul A, Bräuner-Osborne H, Blomberg Jensen M. Heterozygous Mutation (Q459R) in the Calcium-Sensing Receptor Gene Causes Familial Hypocalciuric Hypercalcemia 1 (FHH1). J Clin Endocrinol Metab 2020; 105:5628138. [PMID: 32160303 DOI: 10.1210/clinem/dgz205] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Accepted: 11/14/2019] [Indexed: 01/08/2023]
Abstract
CONTEXT Several heterozygous loss-of-function mutations in the calcium-sensing receptor gene (CASR) leading to elevated ionized serum calcium and familial hypocalciuric hypercalcemia 1 (FHH1) have been characterized. Few mutations are not pathogenic, and previous studies suggested that the Q459R mutation does not result in an FHH1 phenotype. OBJECTIVE We identified a family with a heterozygous CASR Q459R mutation and characterized their calcium homeostasis and the pathophysiological mechanisms of a homozygous and heterozygous Q459R mutation in vitro. DESIGN The index patient and her family had clinical, biochemical, and genetic analyses performed. In vitro functional characterization of homozygous and heterozygous (Q459R) mutations was conducted by determining CaSR cell-surface expression and inositol monophosphate (IP1) signaling in transiently transfected human embryonic kidney 293A (HEK293A) cells. RESULTS All 3 heterozygous carriers had mild asymptomatic hypercalcemia, hypocalciuria, and 2 had elevated serum parathyroid hormone (PTH). In vitro characterization in HEK293A cells revealed that CASR Q459R is a loss-of-function mutation with no impact on cell-surface expression. Cells with the homozygous Q459R genotype had significantly reduced calcium potency of IP1 signaling compared to wild type, whereas the heterozygous Q459R also had lower calcium potency albeit not significantly different from wild type. CONCLUSION A loss-of-function Q459R mutation in CASR in a family caused FHH1 characterized by elevated ionized calcium and PTH and low calcium excretion. The marked presence of CaSR at the membrane and inhibition of IP1 signaling in vitro suggest that calcimimetics may be functional in patients with this mutation, which seems to be a mild loss-of-function mutation associated with autosomal dominant transmission of FHH1.
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Affiliation(s)
- Ida Marie Boisen
- Group of Skeletal, Mineral, and Gonadal Endocrinology, Department of Growth and Reproduction, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Iris Mos
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | - Anders Juul
- Department of Growth and Reproduction, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Hans Bräuner-Osborne
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Martin Blomberg Jensen
- Group of Skeletal, Mineral, and Gonadal Endocrinology, Department of Growth and Reproduction, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
- Division of Bone and Mineral Research, Harvard School of Dental Medicine/Harvard Medical School, Harvard University, Boston, MA, US
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26
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Mos I, Jacobsen SE, Foster SR, Bräuner-Osborne H. Calcium-Sensing Receptor Internalization Is β-Arrestin-Dependent and Modulated by Allosteric Ligands. Mol Pharmacol 2019; 96:463-474. [PMID: 31399503 DOI: 10.1124/mol.119.116772] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Accepted: 07/30/2019] [Indexed: 02/14/2025] Open
Abstract
G protein-coupled receptor (GPCR) internalization is crucial for the termination of GPCR activity, and in some cases is associated with G protein-independent signaling and endosomal receptor signaling. To date, internalization has been studied in great detail for class A GPCRs; whereas it is not well established to what extent the observations can be generalized to class C GPCRs, including the extracellular calcium-sensing receptor (CaSR). The CaSR is a prototypical class C GPCR that maintains stable blood calcium (Ca2+) levels by sensing minute changes in extracellular free Ca2+ It is thus necessary that the activity of the CaSR is tightly regulated, even while continuously being exposed to its endogenous agonist. Previous studies have used overexpression of intracellular proteins involved in GPCR trafficking, pathway inhibitors, and cell-surface expression or functional desensitization as indirect measures to investigate CaSR internalization. However, there is no general consensus on the processes involved, and the mechanism of CaSR internalization remains poorly understood. The current study provides new insights into the internalization mechanism of the CaSR. We have used a state-of-the-art time-resolved fluorescence resonance energy transfer-based internalization assay to directly measure CaSR internalization in real-time. We demonstrate that the CaSR displays both constitutive and concentration-dependent Ca2+-mediated internalization. For the first time, we conclusively show that CaSR internalization is sensitive to immediate positive and negative modulation by the CaSR-specific allosteric modulators N-(3-[2-chlorophenyl]propyl)-(R)-α-methyl-3-methoxybenzylamine (NPS R-568) and 2-chloro-6-[(2R)-2-hydroxy-3-[(2-methyl-1-naphthalen-2-ylpropan-2-yl)amino]propoxy]benzonitrile (NPS 2143), respectively. In addition, we provide compelling evidence that CaSR internalization is β-arrestin-dependent while interestingly being largely independent of Gq/11 and Gi/o protein signaling. SIGNIFICANCE STATEMENT: A novel highly efficient cell-based real-time internalization assay to show that calcium-sensing receptor (CaSR) internalization is β-arrestin-dependent and sensitive to modulation by allosteric ligands.
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Affiliation(s)
- Iris Mos
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Stine E Jacobsen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Simon R Foster
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Hans Bräuner-Osborne
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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27
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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: 15] [Impact Index Per Article: 2.1] [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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28
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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: 25] [Impact Index Per Article: 3.6] [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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29
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Hellyer SD, Albold S, Wang T, Chen ANY, May LT, Leach K, Gregory KJ. "Selective" Class C G Protein-Coupled Receptor Modulators Are Neutral or Biased mGlu 5 Allosteric Ligands. Mol Pharmacol 2018; 93:504-514. [PMID: 29514854 DOI: 10.1124/mol.117.111518] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Accepted: 03/01/2018] [Indexed: 02/14/2025] Open
Abstract
Numerous positive and negative allosteric modulators (PAMs and NAMs) of class C G protein-coupled receptors (GPCRs) have been developed as valuable preclinical pharmacologic tools and therapeutic agents. Although many class C GPCR allosteric modulators have undergone subtype selectivity screening, most assay paradigms have failed to perform rigorous pharmacologic assessment. Using mGlu5 as a representative class C GPCR, we tested the hypothesis that allosteric modulator selectivity was based on cooperativity rather than affinity. Specifically, we aimed to identify ligands that bound to mGlu5 but exhibited neutral cooperativity with mGlu5 agonists. We additionally evaluated the potential for these ligands to exhibit biased pharmacology. Radioligand binding, intracellular calcium (iCa2+) mobilization, and inositol monophosphate (IP1) accumulation assays were undertaken in human embryonic kidney cells expressing low levels of rat mGlu5 (HEK293A-mGlu5-low) for diverse allosteric chemotypes. Numerous "non-mGlu5" class C GPCR allosteric modulators incompletely displaced allosteric mGlu5 radioligand [3H]methoxy-PEPy binding, consistent with a negative allosteric interaction. Affinity estimates for CPCCOEt (mGlu1 ligand), PHCCC (mGlu4 ligand), GS39783 (GABAB ligand), AZ12216052 (mGlu8 ligand), and CGP7930 (GABAB ligand) at mGlu5 were within 10-fold of their target receptor. Most class C GPCR allosteric modulators had neutral cooperativity with both orthosteric and allosteric mGlu5 agonists in functional assays; however, NPS2143 (calcium-sensing receptor (CaSR) NAM), cinacalcet (CaSR PAM), CGP7930, and AZ12216052 were partial mGlu5 agonists for IP1 accumulation, but not iCa2+ mobilization. By using mGlu5 as a model class C GPCR, we find that for many class C GPCR allosteric modulators, subtype selectivity is driven by cooperativity and misinterpreted owing to unappreciated bias.
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Affiliation(s)
- Shane D Hellyer
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia
| | - Sabine Albold
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia
| | - Taide Wang
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia
| | - Amy N Y Chen
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia
| | - Lauren T May
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia
| | - Katie Leach
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia
| | - Karen J Gregory
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria, Australia
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Gerbino A, Colella M. The Different Facets of Extracellular Calcium Sensors: Old and New Concepts in Calcium-Sensing Receptor Signalling and Pharmacology. Int J Mol Sci 2018; 19:E999. [PMID: 29584660 PMCID: PMC5979557 DOI: 10.3390/ijms19040999] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 03/23/2018] [Accepted: 03/25/2018] [Indexed: 12/14/2022] Open
Abstract
The current interest of the scientific community for research in the field of calcium sensing in general and on the calcium-sensing Receptor (CaR) in particular is demonstrated by the still increasing number of papers published on this topic. The extracellular calcium-sensing receptor is the best-known G-protein-coupled receptor (GPCR) able to sense external Ca2+ changes. Widely recognized as a fundamental player in systemic Ca2+ homeostasis, the CaR is ubiquitously expressed in the human body where it activates multiple signalling pathways. In this review, old and new notions regarding the mechanisms by which extracellular Ca2+ microdomains are created and the tools available to measure them are analyzed. After a survey of the main signalling pathways triggered by the CaR, a special attention is reserved for the emerging concepts regarding CaR function in the heart, CaR trafficking and pharmacology. Finally, an overview on other Ca2+ sensors is provided.
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Affiliation(s)
- Andrea Gerbino
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari, 70121 Bari, Italy.
| | - Matilde Colella
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari, 70121 Bari, Italy.
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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: 27] [Impact Index Per Article: 3.9] [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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