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Saglia C, Arruga F, Scolari C, Kalantari S, Albanese S, Bracciamà V, Corso Faini A, Brach Del Prever G, Luca M, Romeo C, Mioli F, Migliorero M, Tessaris D, Carli D, Amoroso A, Vaisitti T, De Sanctis L, Deaglio S. Functional evaluation of a novel nonsense variant of the calcium-sensing receptor gene leading to hypocalcemia. Eur J Endocrinol 2024; 190:296-306. [PMID: 38561929 DOI: 10.1093/ejendo/lvae035] [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: 12/04/2023] [Revised: 03/06/2024] [Accepted: 03/08/2024] [Indexed: 04/04/2024]
Abstract
OBJECTIVE The calcium-sensing receptor (CASR) gene encodes a G protein-coupled receptor crucial for calcium homeostasis. Gain-of-function CASR variants result in hypocalcemia, while loss-of-function variants lead to hypercalcemia. This study aims to assess the functional consequences of the novel nonsense CASR variant [c.2897_2898insCTGA, p.(Gln967*) (Q967*)] identified in adolescent patient with chronic hypocalcemia, a phenotype expected for a gain-of-function variants. DESIGN AND METHODS To functionally characterize the Q967* mutant receptor, both wild-type (WT) and mutant CASR were transiently transfected into HEK293T cells and calcium-sensing receptor (CaSR) protein expression and functions were comparatively evaluated using multiple read-outs. RESULTS Western blot analysis revealed that the CaSR mutant protein displayed a lower molecular weight compared with the WT, consistent with the loss of the last 122 amino acids in the intracellular domain. Mitogen-activated protein kinase activation and serum responsive element luciferase assays demonstrated that the mutant receptor had higher baseline activity than the WT. Extracellular-signal-regulated kinase/c-Jun N-terminal kinase phosphorylation, however, remained consistently high in the mutant, without significant modulations following exposure to increasing extracellular calcium (Ca2+o) levels, suggesting that the mutant receptor is more sensitive to Ca2+o compared with the WT. CONCLUSIONS This study provides functional validation of the pathogenicity of a novel nonsense CASR variant, resulting in an abnormally hyperfunctioning protein consistent with the patient's phenotype. Functional analyses indicate that mutant receptor is constitutively active and poorly sensitive to increasing concentrations of extracellular calcium, suggesting that the cytoplasmic tail may contain elements regulating signal transduction.
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Affiliation(s)
- Claudia Saglia
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
| | - Francesca Arruga
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
| | - Caterina Scolari
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
| | - Silvia Kalantari
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
| | - Serena Albanese
- Department of Public Health and Pediatric Sciences, University of Torino, Torino 10126, Italy
- Pediatric Endocrinology, Regina Margherita Childrens' Hospital, Torino 10126, Italy
| | - Valeria Bracciamà
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
| | - Angelo Corso Faini
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
| | - Giulia Brach Del Prever
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
| | - Maria Luca
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
| | - Carmelo Romeo
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
| | - Fiorenza Mioli
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
| | | | - Daniele Tessaris
- Department of Public Health and Pediatric Sciences, University of Torino, Torino 10126, Italy
- Pediatric Endocrinology, Regina Margherita Childrens' Hospital, Torino 10126, Italy
| | - Diana Carli
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
| | - Antonio Amoroso
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
| | - Tiziana Vaisitti
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
| | - Luisa De Sanctis
- Department of Public Health and Pediatric Sciences, University of Torino, Torino 10126, Italy
- Pediatric Endocrinology, Regina Margherita Childrens' Hospital, Torino 10126, Italy
| | - Silvia Deaglio
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
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He F, Wu CG, Gao Y, Rahman SN, Zaoralová M, Papasergi-Scott MM, Gu TJ, Robertson MJ, Seven AB, Li L, Mathiesen JM, Skiniotis G. Allosteric modulation and G-protein selectivity of the Ca 2+-sensing receptor. Nature 2024; 626:1141-1148. [PMID: 38326620 DOI: 10.1038/s41586-024-07055-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Accepted: 01/10/2024] [Indexed: 02/09/2024]
Abstract
The calcium-sensing receptor (CaSR) is a family C G-protein-coupled receptor1 (GPCR) that has a central role in regulating systemic calcium homeostasis2,3. Here we use cryo-electron microscopy and functional assays to investigate the activation of human CaSR embedded in lipid nanodiscs and its coupling to functional Gi versus Gq proteins in the presence and absence of the calcimimetic drug cinacalcet. High-resolution structures show that both Gi and Gq drive additional conformational changes in the activated CaSR dimer to stabilize a more extensive asymmetric interface of the seven-transmembrane domain (7TM) that involves key protein-lipid interactions. Selective Gi and Gq coupling by the receptor is achieved through substantial rearrangements of intracellular loop 2 and the C terminus, which contribute differentially towards the binding of the two G-protein subtypes, resulting in distinct CaSR-G-protein interfaces. The structures also reveal that natural polyamines target multiple sites on CaSR to enhance receptor activation by zipping negatively charged regions between two protomers. Furthermore, we find that the amino acid L-tryptophan, a well-known ligand of CaSR extracellular domains, occupies the 7TM bundle of the G-protein-coupled protomer at the same location as cinacalcet and other allosteric modulators. Together, these results provide a framework for G-protein activation and selectivity by CaSR, as well as its allosteric modulation by endogenous and exogenous ligands.
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Affiliation(s)
- Feng He
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
| | - Cheng-Guo Wu
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
| | - Yang Gao
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
- Department of Cardiology of Sir Run Run Shaw Hospital and Liangzhu Laboratory, Zhejiang University School of Medicine, Hangzhou, China
| | - Sabrina N Rahman
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Magda Zaoralová
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
| | - Makaía M Papasergi-Scott
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
| | - Ting-Jia Gu
- School of Pharmacy, University of Wisconsin-Madison, Madison, WI, USA
| | - Michael J Robertson
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
| | - Alpay B Seven
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
| | - Lingjun Li
- School of Pharmacy, University of Wisconsin-Madison, Madison, WI, USA
| | - Jesper M Mathiesen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Georgios Skiniotis
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA.
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, USA.
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3
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Centeno PP, Binmahfouz LS, Alghamdi K, Ward DT. Inhibition of the calcium-sensing receptor by extracellular phosphate ions and by intracellular phosphorylation. Front Physiol 2023; 14:1154374. [PMID: 37064904 PMCID: PMC10102455 DOI: 10.3389/fphys.2023.1154374] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Accepted: 03/20/2023] [Indexed: 04/03/2023] Open
Abstract
As both a sensor of extracellular calcium (Ca2+o) concentration and a key controller of Ca2+o homeostasis, one of the most interesting properties of the calcium-sensing receptor (CaR) is its sensitivity to, and modulation by, ions and small ligands other than Ca2+. There is emerging evidence that extracellular phosphate can act as a partial, non-competitive CaR antagonist to modulate parathyroid hormone (PTH) secretion, thus permitting the CaR to integrate mineral homeostasis more broadly. Interestingly, phosphorylation of certain intracellular CaR residues can also inhibit CaR responsiveness. Thus, negatively charged phosphate can decrease CaR activity both extracellularly (via association with arginine) and intracellularly (via covalent phosphorylation).
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Affiliation(s)
- Patricia P. Centeno
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom
| | - Lenah S. Binmahfouz
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Khaleda Alghamdi
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Donald T. Ward
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom
- *Correspondence: Donald T. Ward,
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Roy S, Sharma A, Ghosh S. Mechanistic crosstalk of extracellular calcium-mediated regulation of maturation and plasticity in human monocytes. Biochem Biophys Res Commun 2023; 643:39-47. [PMID: 36586157 DOI: 10.1016/j.bbrc.2022.12.054] [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: 11/15/2022] [Revised: 12/19/2022] [Accepted: 12/19/2022] [Indexed: 12/24/2022]
Abstract
Innate immune cells play a pivotal role in controlling tissue repair and rejection after biomaterial implantation. Calcium supplementation regulates cellular responses and alter the pathophysiology of various diseases. A series of macrophage activations through differential plasticity has been observed after cell-to-material interactions. We investigated the role of calcium supplementation in controlling macrophage phenotypes in pro-inflammatory and pre-reparative states. Oxidative defence and mitochondria involvement in cellular plasticity and the sequential M0 to M1 and M1 to M2 transitions were observed after calcium supplementation. This study describes the molecular mechanism of reactive oxygen species and drives the interconnected cellular plasticity of macrophages in the presence of calcium. Gene expression, and immunostaining, revealed a relationship between MHC class II maturation and cellular plasticity. This study elucidated the role of controlled calcium supplementation under various conditions. These findings underscore the molecular mechanism of calcium-mediated immune induction and its favourable use in different calcium-containing biomaterials., essential for tissue regeneration.
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Affiliation(s)
- Subhadeep Roy
- Regenerative Engineering Laboratory, Department of Textile and Fiber Engineering, Indian Institute of Technology, New Delhi, 110016, India
| | - Aarushi Sharma
- Regenerative Engineering Laboratory, Department of Textile and Fiber Engineering, Indian Institute of Technology, New Delhi, 110016, India
| | - Sourabh Ghosh
- Regenerative Engineering Laboratory, Department of Textile and Fiber Engineering, Indian Institute of Technology, New Delhi, 110016, India.
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5
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Brennan SC, Mun HC, Delbridge L, Kuchel PW, Conigrave AD. Temperature sensing by the calcium-sensing receptor. Front Physiol 2023; 14:1117352. [PMID: 36818436 PMCID: PMC9931745 DOI: 10.3389/fphys.2023.1117352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Accepted: 01/16/2023] [Indexed: 02/05/2023] Open
Abstract
Whether GPCRs support the sensing of temperature as well as other chemical and physical modalities is not well understood. Introduction: Extracellular Ca2+ concentration (Ca2+ o) modulates core body temperature and the firing rates of temperature-sensitive CNS neurons, and hypocalcemia provokes childhood seizures. However, it is not known whether these phenomena are mediated by Ca2+ o-sensing GPCRs, including the calcium-sensing receptor (CaSR). In favor of the hypothesis, CaSRs are expressed in hypothalamic regions that support core temperature regulation, and autosomal dominant hypocalcemia, due to CaSR activating mutations, is associated with childhood seizures. Methods: Herein, we tested whether CaSR-dependent signaling is temperature sensitive using an established model system, CaSR-expressing HEK-293 cells. Results: We found that the frequency of Ca2+ o-induced Ca2+ i oscillations but not the integrated response was linearly dependent on temperature in a pathophysiologically relevant range. Chimeric receptor analysis showed that the receptor's C-terminus is required for temperature-dependent modulation and experiments with the PKC inhibitor GF109203X and CaSR mutants T888A and T888M, which eliminate a key phosphorylation site, demonstrated the importance of repetitive phosphorylation and dephosphorylation. Discussion and Conclusion: CaSRs mediate temperature-sensing and the mechanism, dependent upon repetitive phosphorylation and dephosphorylation, suggests that GPCRs more generally contribute to temperature-sensing.
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Affiliation(s)
- Sarah C. Brennan
- School of Life and Environmental Sciences, Faculty of Science, The University of Sydney, Sydney, NSW, Australia,Charles Perkins Centre, University of Sydney, Sydney, NSW, Australia
| | - Hee-chang Mun
- Charles Perkins Centre, University of Sydney, Sydney, NSW, Australia
| | - Leigh Delbridge
- Department of Surgery, Mater Hospital, North Sydney, NSW, Australia
| | - Philip W. Kuchel
- School of Life and Environmental Sciences, Faculty of Science, The University of Sydney, Sydney, NSW, Australia
| | - Arthur D. Conigrave
- School of Life and Environmental Sciences, Faculty of Science, The University of Sydney, Sydney, NSW, Australia,Charles Perkins Centre, University of Sydney, Sydney, NSW, Australia,*Correspondence: Arthur D. Conigrave,
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6
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Huang A, Binmahfouz L, Hancock DP, Anderson PH, Ward DT, Conigrave AD. Calcium-Sensing Receptors Control CYP27B1-Luciferase Expression: Transcriptional and Posttranscriptional Mechanisms. J Endocr Soc 2021; 5:bvab057. [PMID: 34337274 PMCID: PMC8317635 DOI: 10.1210/jendso/bvab057] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Indexed: 12/19/2022] Open
Abstract
25-hydroxyvitamin D 1α-hydroxylase (encoded by CYP27B1), which catalyzes the synthesis of 1,25-dihydroxyvitamin D3, is subject to negative or positive modulation by extracellular Ca2+ (Ca2+o) depending on the tissue. However, the Ca2+ sensors and underlying mechanisms are unidentified. We tested whether calcium-sensing receptors (CaSRs) mediate Ca2+o-dependent control of 1α-hydroxylase using HEK-293 cells stably expressing the CaSR (HEK-CaSR cells). In HEK-CaSR cells, but not control HEK-293 cells, cotransfected with reporter genes for CYP27B1-Photinus pyralis (firefly) luciferase and control Renilla luciferase, an increase in Ca2+o from 0.5mM to 3.0mM induced a 2- to 3-fold increase in firefly luciferase activity as well as mRNA and protein levels. Surprisingly, firefly luciferase was specifically suppressed at Ca2+o ≥ 5.0mM, demonstrating biphasic Ca2+o control. Both phases were mediated by CaSRs as revealed by positive and negative modulators. However, Ca2+o induced simple monotonic increases in firefly luciferase and endogenous CYP27B1 mRNA levels, indicating that the inhibitory effect of high Ca2+o was posttranscriptional. Studies with inhibitors and the CaSR C-terminal mutant T888A identified roles for protein kinase C (PKC), phosphorylation of T888, and extracellular regulated protein kinase (ERK)1/2 in high Ca2+o-dependent suppression of firefly luciferase. Blockade of both PKC and ERK1/2 abolished Ca2+o-stimulated firefly luciferase, demonstrating that either PKC or ERK1/2 is sufficient to stimulate the CYP27B1 promoter. A key CCAAT box (−74 bp to −68 bp), which is regulated downstream of PKC and ERK1/2, was required for both basal transcription and Ca2+o-mediated transcriptional upregulation. The CaSR mediates Ca2+o-dependent transcriptional upregulation of 1α-hydroxylase and an additional CaSR-mediated mechanism is identified by which Ca2+o can promote luciferase and possibly 1α-hydroxylase breakdown.
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Affiliation(s)
- Alice Huang
- School of Life and Environmental Sciences, Charles Perkins Centre (D17), University of Sydney, NSW 2006Australia
| | - Lenah Binmahfouz
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, UK.,Department of Pharmacology and Toxicology, Faculty of Pharmacy, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - Dale P Hancock
- School of Life and Environmental Sciences, Charles Perkins Centre (D17), University of Sydney, NSW 2006Australia
| | - Paul H Anderson
- Clinical and Health Sciences, Health and Biomedical Innovation, University of South Australia, Adelaide, SA, 5001, Australia
| | - Donald T Ward
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, UK
| | - Arthur D Conigrave
- School of Life and Environmental Sciences, Charles Perkins Centre (D17), University of Sydney, NSW 2006Australia
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7
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Leach K, Hannan FM, Josephs TM, Keller AN, Møller TC, Ward DT, Kallay E, Mason RS, Thakker RV, Riccardi D, Conigrave AD, Bräuner-Osborne H. International Union of Basic and Clinical Pharmacology. CVIII. Calcium-Sensing Receptor Nomenclature, Pharmacology, and Function. Pharmacol Rev 2020; 72:558-604. [PMID: 32467152 PMCID: PMC7116503 DOI: 10.1124/pr.119.018531] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The calcium-sensing receptor (CaSR) is a class C G protein-coupled receptor that responds to multiple endogenous agonists and allosteric modulators, including divalent and trivalent cations, L-amino acids, γ-glutamyl peptides, polyamines, polycationic peptides, and protons. The CaSR plays a critical role in extracellular calcium (Ca2+ o) homeostasis, as demonstrated by the many naturally occurring mutations in the CaSR or its signaling partners that cause Ca2+ o homeostasis disorders. However, CaSR tissue expression in mammals is broad and includes tissues unrelated to Ca2+ o homeostasis, in which it, for example, regulates the secretion of digestive hormones, airway constriction, cardiovascular effects, cellular differentiation, and proliferation. Thus, although the CaSR is targeted clinically by the positive allosteric modulators (PAMs) cinacalcet, evocalcet, and etelcalcetide in hyperparathyroidism, it is also a putative therapeutic target in diabetes, asthma, cardiovascular disease, and cancer. The CaSR is somewhat unique in possessing multiple ligand binding sites, including at least five putative sites for the "orthosteric" agonist Ca2+ o, an allosteric site for endogenous L-amino acids, two further allosteric sites for small molecules and the peptide PAM, etelcalcetide, and additional sites for other cations and anions. The CaSR is promiscuous in its G protein-coupling preferences, and signals via Gq/11, Gi/o, potentially G12/13, and even Gs in some cell types. Not surprisingly, the CaSR is subject to biased agonism, in which distinct ligands preferentially stimulate a subset of the CaSR's possible signaling responses, to the exclusion of others. The CaSR thus serves as a model receptor to study natural bias and allostery. SIGNIFICANCE STATEMENT: The calcium-sensing receptor (CaSR) is a complex G protein-coupled receptor that possesses multiple orthosteric and allosteric binding sites, is subject to biased signaling via several different G proteins, and has numerous (patho)physiological roles. Understanding the complexities of CaSR structure, function, and biology will aid future drug discovery efforts seeking to target this receptor for a diversity of diseases. This review summarizes what is known to date regarding key structural, pharmacological, and physiological features of the CaSR.
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Affiliation(s)
- Katie Leach
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Fadil M Hannan
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Tracy M Josephs
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Andrew N Keller
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Thor C Møller
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Donald T Ward
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Enikö Kallay
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Rebecca S Mason
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Rajesh V Thakker
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Daniela Riccardi
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Arthur D Conigrave
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Hans Bräuner-Osborne
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
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8
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Sensing Extracellular Calcium - An Insight into the Structure and Function of the Calcium-Sensing Receptor (CaSR). ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1131:1031-1063. [PMID: 31646544 DOI: 10.1007/978-3-030-12457-1_41] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The calcium-sensing receptor (CaSR) is a G protein-coupled receptor that plays a key role in calcium homeostasis, by sensing free calcium levels in blood and regulating parathyroid hormone secretion in response. The CaSR is highly expressed in parathyroid gland and kidney where its role is well characterised, but also in other tissues where its function remains to be determined. The CaSR can be activated by a variety of endogenous ligands, as well as by synthetic modulators such as Cinacalcet, used in the clinic to treat secondary hyperparathyroidism in patients with chronic kidney disease. The CaSR couples to multiple G proteins, in a tissue-specific manner, activating several signalling pathways and thus regulating diverse intracellular events. The multifaceted nature of this receptor makes it a valuable therapeutic target for calciotropic and non-calciotropic diseases. It is therefore essential to understand the complexity behind the pharmacology, trafficking, and signalling characteristics of this receptor. This review provides an overview of the latest knowledge about the CaSR and discusses future hot topics in this field.
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9
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Chavez-Abiega S, Goedhart J, Bruggeman FJ. Physical biology of GPCR signalling dynamics inferred from fluorescence spectroscopy and imaging. Curr Opin Struct Biol 2019; 55:204-211. [PMID: 31319372 DOI: 10.1016/j.sbi.2019.05.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 04/30/2019] [Accepted: 05/08/2019] [Indexed: 12/20/2022]
Abstract
The physical biology of G protein-coupled receptor (GPCR) signalling can be inferred from imaging of single molecules and single living cells. In this opinion paper, we highlight recent developments in technologies to study GPCR signalling in vitro and in cyto. We start from mobility and localisation characteristics of single receptors in membranes. Subsequently, we discuss the kinetics of shifts in receptor-conformation equilibrium due to allosteric binding events and G protein activation. We continue with recent insights into downstream signalling and the role of delayed negative feedback to suppress GPCR signalling. Finally, we discuss new strategies to reveal how the multiplex signalling responses of cells to ligand mixtures, mediated by their entire receptor arsenal, can be disentangled, using single-cell data.
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Affiliation(s)
- Sergei Chavez-Abiega
- Section Molecular Cytology, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, NL-1098 XH, Amsterdam, The Netherlands; Section Systems Bioinformatics, Amsterdam Institute for Molecules, Medicines and Systems, VU University, De Boelelaan 1085, NL-1081 HV, Amsterdam, The Netherlands
| | - Joachim Goedhart
- Section Molecular Cytology, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, NL-1098 XH, Amsterdam, The Netherlands
| | - Frank Johannes Bruggeman
- Section Systems Bioinformatics, Amsterdam Institute for Molecules, Medicines and Systems, VU University, De Boelelaan 1085, NL-1081 HV, Amsterdam, The Netherlands.
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10
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Binmahfouz LS, Centeno PP, Conigrave AD, Ward DT. Identification of Serine-875 as an Inhibitory Phosphorylation Site in the Calcium-Sensing Receptor. Mol Pharmacol 2019; 96:204-211. [DOI: 10.1124/mol.119.116178] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Accepted: 05/20/2019] [Indexed: 11/22/2022] Open
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11
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Conigrave AD. The Calcium-Sensing Receptor and the Parathyroid: Past, Present, Future. Front Physiol 2016; 7:563. [PMID: 28018229 PMCID: PMC5156698 DOI: 10.3389/fphys.2016.00563] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2016] [Accepted: 11/07/2016] [Indexed: 12/13/2022] Open
Abstract
Parathyroid hormone (PTH) defends the extracellular fluid from hypocalcemia and has powerful and well-documented actions on the skeleton and renal tubular system. To achieve a satisfactory stable plasma calcium level, the secretion of PTH, and the resulting serum PTH level, is titrated carefully to the prevailing plasma ionized Ca2+ concentration via a Ca2+ sensing mechanism that mediates feedback inhibition of PTH secretion. Herein, I consider the properties of the parathyroid Ca2+ sensing mechanism, the identity of the Ca2+ sensor, the intracellular biochemical mechanisms that it controls, the manner of its integration with other components of the PTH secretion control mechanism, and its modulation by other nutrients. Together the well-established, recently elucidated, and yet-to-be discovered elements of the story constitute the past, present, and future of the parathyroid and its calcium-sensing receptor (CaSR).
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Affiliation(s)
- Arthur D Conigrave
- Faculties of Science and Medicine, School of Life and Environmental Sciences, Charles Perkins Centre, University of Sydney Sydney, NSW, Australia
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12
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The calcium-sensing receptor and the hallmarks of cancer. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:1398-407. [DOI: 10.1016/j.bbamcr.2015.11.017] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Revised: 11/17/2015] [Accepted: 11/18/2015] [Indexed: 02/07/2023]
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13
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Young SH, Rey O, Rozengurt E. Intracellular Ca(2+) oscillations generated via the extracellular Ca(2+)-sensing receptor (CaSR) in response to extracellular Ca(2+) or L-phenylalanine: Impact of the highly conservative mutation Ser170Thr. Biochem Biophys Res Commun 2015; 467:1-6. [PMID: 26431875 DOI: 10.1016/j.bbrc.2015.09.144] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 09/26/2015] [Indexed: 12/21/2022]
Abstract
The extracellular Ca(2+)-sensing receptor (CaSR) is an allosteric protein that responds to changes in the extracellular concentration of Ca(2+) ([Ca(2+)]e) and aromatic amino acids with the production of different patterns of oscillations in intracellular Ca(2+) concentration ([Ca(2+)]i). An increase in [Ca(2+)]e stimulates sinusoidal oscillations in [Ca(2+)]i whereas aromatic amino acid-induced CaR activation in the presence of a threshold [Ca(2+)]e promotes transient oscillations in [Ca(2+)]i. Here, we examined spontaneous and ligand-evoked [Ca(2+)]i oscillations in single HEK-293 cells transfected with the wild type CaSR or with a mutant CaSR in which Ser170 was converted to Thr (CaSRS170T). Our analysis demonstrates that cells expressing CaSRS170T display [Ca(2+)]i oscillations in the presence of low concentrations of extracellular Ca(2+) and respond to L-Phe with robust transient [Ca(2+)]i oscillations. Our results indicate that the S170T mutation induces a marked increase in CaSR sensitivity to [Ca(2+)]e and imply that the allosteric regulation of the CaSR by aromatic amino acids is not only mediated by an heterotropic positive effect on Ca(2+) binding cooperativity but, as biased agonists, aromatic amino acids stabilize a CaSR conformation that couples to a different signaling pathway leading to transient [Ca(2+)]i oscillations.
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Affiliation(s)
- Steven H Young
- Division of Digestive Diseases, Department of Medicine, CURE: Digestive Diseases Research Center, David Geffen School of Medicine and Molecular Biology Institute, University of California at Los Angeles, Los Angeles, CA 90095, USA
| | - Osvaldo Rey
- Institute of Immunology, Genetics and Metabolism, Consejo Nacional de Investigaciones Cientificas y Tecnicas, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Enrique Rozengurt
- Division of Digestive Diseases, Department of Medicine, CURE: Digestive Diseases Research Center, David Geffen School of Medicine and Molecular Biology Institute, University of California at Los Angeles, Los Angeles, CA 90095, USA; Veterans Affairs West Los Angeles Healthcare System, Los Angeles, CA, USA.
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14
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Abstract
We have investigated how CaSR activation enhances sympathetic axon growth. CaSR activation promotes phosphorylation of ERK1 and ERK2. Inhibition of ERK1/ERK2 phosphorylation blocks CaSR-promoted axon growth. CaSR-promoted axon growth requires a discrete region of the cytoplasmic domain.
The extracellular calcium-sensing receptor (CaSR) is a G-protein coupled receptor that monitors the systemic extracellular free ionized calcium level ([Ca2+]o) in organs involved in systemic [Ca2+]o homeostasis. CaSR is widely expressed in the nervous system and its activation promotes axon and dendrite growth during development, but the mechanism by which it does this is not known. Here we show that enhanced axon growth and branching from cultured embryonic sympathetic neurons by activation of the endogenous CaSR depends on the presence of nerve growth factor (NGF). Our observation that activation of overexpressed CaSR promotes axon growth in NGF-free medium has enabled us to investigate CaSR downstream signaling contributing to axon growth in the absence of NGF signaling. We show that activation of overexpressed CaSR leads to activation of ERK1 and ERK2, and pharmacological inhibition of CaSR-dependent ERK1/ERK2 activation prevents CaSR-dependent axon growth. Analysis of axon growth from cultured neurons expressing deletion mutants of the CaSR cytoplasmic tail revealed that the region between alanine 877 and glycine 907 is required for promoting axon growth that is distinct from the high-affinity filamin-A binding site that has previously been implicated in ERK1/ERK2 activation.
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Affiliation(s)
- Thomas N Vizard
- School of Biosciences, Biomedical Building, Museum Avenue, Cardiff CF10 3US, UK.
| | - Michael Newton
- School of Biosciences, Biomedical Building, Museum Avenue, Cardiff CF10 3US, UK
| | - Laura Howard
- School of Biosciences, Biomedical Building, Museum Avenue, Cardiff CF10 3US, UK
| | - Sean Wyatt
- School of Biosciences, Biomedical Building, Museum Avenue, Cardiff CF10 3US, UK
| | - Alun M Davies
- School of Biosciences, Biomedical Building, Museum Avenue, Cardiff CF10 3US, UK
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15
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Role of post-translational modifications on structure, function and pharmacology of class C G protein-coupled receptors. Eur J Pharmacol 2015; 763:233-40. [PMID: 25981296 DOI: 10.1016/j.ejphar.2015.05.015] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Revised: 03/06/2015] [Accepted: 05/11/2015] [Indexed: 11/22/2022]
Abstract
G protein-coupled receptors are divided into three classes (A, B and C) based on homology of their seven transmembrane domains. Class C is the smallest class with 22 human receptor subtypes including eight metabotropic glutamate (mGlu1-8) receptors, two GABAB receptors (GABAB1 and GABAB2), three taste receptors (T1R1-3), one calcium-sensing (CaS) receptor, one GPCR, class C, group 6, subtype A (GPRC6) receptor, and seven orphan receptors. G protein-coupled receptors undergo a number of post-translational modifications, which regulate their structure, function and/or pharmacology. Here, we review the existence of post-translational modifications in class C G protein-coupled receptors and their regulatory roles, with particular focus on glycosylation, phosphorylation, ubiquitination, SUMOylation, disulphide bonding and lipidation.
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16
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Willems PHGM, Pahle J, Stalpers XL, Mugahid D, Nikolaew A, Koopman WJH, Kummer U. PKC-mediated inhibitory feedback of the cholecystokinin 1 receptor controls the shape of oscillatory Ca2+signals. FEBS J 2015; 282:2187-201. [DOI: 10.1111/febs.13267] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Revised: 01/31/2015] [Accepted: 03/11/2015] [Indexed: 01/10/2023]
Affiliation(s)
- Peter H. G. M. Willems
- Department of Biochemistry; Radboud Institute for Molecular Life Sciences and Centre for Systems Biology and Bioenergetics; Radboud University Medical Center; Nijmegen The Netherlands
| | - Jürgen Pahle
- BIOMS; BioQuant; Heidelberg University; Germany
- School of Computer Science; Manchester Institute of Biotechnology; University of Manchester; UK
| | - Xenia L. Stalpers
- Department of Biochemistry; Radboud Institute for Molecular Life Sciences and Centre for Systems Biology and Bioenergetics; Radboud University Medical Center; Nijmegen The Netherlands
| | - Douaa Mugahid
- Department of Modelling of Biological Processes; COS Heidelberg/BioQuant; Heidelberg University; Germany
| | - Alexander Nikolaew
- Department of Modelling of Biological Processes; COS Heidelberg/BioQuant; Heidelberg University; Germany
| | - Werner J. H. Koopman
- Department of Biochemistry; Radboud Institute for Molecular Life Sciences and Centre for Systems Biology and Bioenergetics; Radboud University Medical Center; Nijmegen The Netherlands
| | - Ursula Kummer
- Department of Modelling of Biological Processes; COS Heidelberg/BioQuant; Heidelberg University; Germany
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17
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Huang S, Ren Y, Wang P, Li Y, Wang X, Zhuang H, Fang R, Wang Y, Liu N, Hehir M, Zhou JX. Transcription Factor CREB is Involved in CaSR-mediated Cytoskeleton Gene Expression. Anat Rec (Hoboken) 2014; 298:501-12. [PMID: 25382680 DOI: 10.1002/ar.23089] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2014] [Accepted: 09/13/2014] [Indexed: 12/21/2022]
Affiliation(s)
- Shuaishuai Huang
- Department of Medical School; Ningbo University; Ningbo 315211 China
- Department of the Center for Translational Medicine; The Affiliated Hospital, Ningbo University School of Medicine; Ningbo 315020 China
| | - Yu Ren
- Department of Urologic Surgery; Ningbo Urology and Nephrology Hospital, Ningbo University; Ningbo 315000 China
| | - Ping Wang
- Department of Medical School; Ningbo University; Ningbo 315211 China
- Department of the Center for Translational Medicine; The Affiliated Hospital, Ningbo University School of Medicine; Ningbo 315020 China
| | - Yanyuan Li
- Department of Pathology; First Affiliated Hospital, Zhejiang University School of Medicine; Hangzhou P.R.310003 China
| | - Xue Wang
- Department of Medical School; Ningbo University; Ningbo 315211 China
- Department of the Center for Translational Medicine; The Affiliated Hospital, Ningbo University School of Medicine; Ningbo 315020 China
| | - Haihui Zhuang
- Department of Medical School; Ningbo University; Ningbo 315211 China
- Department of the Center for Translational Medicine; The Affiliated Hospital, Ningbo University School of Medicine; Ningbo 315020 China
| | - Rong Fang
- Department of Medical School; Ningbo University; Ningbo 315211 China
- Department of the Center for Translational Medicine; The Affiliated Hospital, Ningbo University School of Medicine; Ningbo 315020 China
| | - Yuduo Wang
- Department of Medical School; Ningbo University; Ningbo 315211 China
| | - Ningsheng Liu
- Department of Medical School; Ningbo University; Ningbo 315211 China
| | - Michael Hehir
- Department of Medical School; Ningbo University; Ningbo 315211 China
- Department of the Center for Translational Medicine; The Affiliated Hospital, Ningbo University School of Medicine; Ningbo 315020 China
| | - Jeff X. Zhou
- Department of Medical School; Ningbo University; Ningbo 315211 China
- Department of the Center for Translational Medicine; The Affiliated Hospital, Ningbo University School of Medicine; Ningbo 315020 China
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18
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Leach K, Sexton PM, Christopoulos A, Conigrave AD. Engendering biased signalling from the calcium-sensing receptor for the pharmacotherapy of diverse disorders. Br J Pharmacol 2014; 171:1142-55. [PMID: 24111791 DOI: 10.1111/bph.12420] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Revised: 08/22/2013] [Accepted: 08/26/2013] [Indexed: 12/14/2022] Open
Abstract
The human calcium-sensing receptor (CaSR) is widely expressed in the body, where its activity is regulated by multiple orthosteric and endogenous allosteric ligands. Each ligand stabilizes a unique subset of conformational states, which enables the CaSR to couple to distinct intracellular signalling pathways depending on the extracellular milieu in which it is bathed. Differential signalling arising from distinct receptor conformations favoured by each ligand is referred to as biased signalling. The outcome of CaSR activation also depends on the cell type in which it is expressed. Thus, the same ligand may activate diverse pathways in distinct cell types. Given that the CaSR is implicated in numerous physiological and pathophysiological processes, it is an ideal target for biased ligands that could be rationally designed to selectively regulate desired signalling pathways in preferred cell types.
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Affiliation(s)
- K Leach
- Pharmaceutical Sciences, Monash University, Melbourne, Vic., Australia
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19
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Kim JY, Kim N, Yenari MA, Chang W. Hypothermia and pharmacological regimens that prevent overexpression and overactivity of the extracellular calcium-sensing receptor protect neurons against traumatic brain injury. J Neurotrauma 2014; 30:1170-6. [PMID: 23360235 DOI: 10.1089/neu.2012.2691] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Traumatic brain injury (TBI) leads to acute functional deficit in the brain. Molecular events underlying TBI remain unclear. In mouse brains, we found controlled cortical impact (CCI) injury induced overexpression of the extracellular calcium-sensing receptor (CaSR), which is known to stimulate neuronal activity and accumulation of intracellular Ca(2+) and concurrent down-regulation of type B or metabotropic GABA receptor 1 (GABA-B-R1), a prominent inhibitory pathway in the brain. These changes in protein expression preceded and were closely associated with the loss of brain tissue, as indicated by the increased size of cortical cavity at impact sites, and the development of motor deficit, as indicated by the increased frequency of right-biased swing and turn in the CCI mice. Mild hypothermia, an established practice of neuroprotection for brain ischemia, partially but significantly blunted all of the above effects of CCI. Administration of CaSR antagonist NPS89636 mimicked hypothermia to reduce loss of brain tissue and motor functions in the CCI mice. These data together support the concept that CaSR overexpression and overactivity play a causal role in potentiating TBI potentially by stimulating excitatory neuronal responses and by interfering with inhibitory GABA-B-R signaling and that the CaSR could be a novel target for neuroprotection against TBI.
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Affiliation(s)
- Jong Youl Kim
- University of California, San Francisco, California, USA
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20
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Young SH, Rey O, Sinnett-Smith J, Rozengurt E. Intracellular Ca2+ oscillations generated via the Ca2+-sensing receptor are mediated by negative feedback by PKCα at Thr888. Am J Physiol Cell Physiol 2013; 306:C298-306. [PMID: 24336654 DOI: 10.1152/ajpcell.00194.2013] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
To clarify the mechanism(s) underlying intracellular Ca(2+) concentration ([Ca(2+)]i) oscillations induced by an elevation in extracellular Ca(2+) concentration ([Ca(2+)]e) via the extracellular Ca(2+)-sensing receptor (CaR), we analyzed the pattern of [Ca(2+)]i response in multiple (2,303) individual HEK-293 cells transfected with the human CaR. An increase in the [Ca(2+)]e from 1.5 to 3 mM produced oscillatory fluctuations in [Ca(2+)]i in 70% of the cell population. To determine the role of PKC in the generation of [Ca(2+)]i oscillations, cells were exposed to increasing concentrations (0.5-5 μM) of the preferential PKC inhibitor Ro-31-8220 before stimulation by extracellular Ca(2+). Ro-31-8220 at 3-5 μM completely eliminated the [Ca(2+)]e-evoked [Ca(2+)]i oscillations and transformed the pattern to a peak and sustained plateau response. Treatment with other broad PKC inhibitors, including GFI or Gö6983, produced an identical response. Similarly, treatment with Ro-31-8220 or GFI eliminated [Ca(2+)]e-evoked [Ca(2+)]i oscillations in colon-derived SW-480 cells expressing the CaR. Treatment with inhibitors targeting classic PKCs, including Gö6976 and Ro-32-0432 as well as small interfering RNA-mediated knockdown of PKCα, strikingly reduced the proportion of cell displaying [Ca(2+)]e-evoked [Ca(2+)]i oscillations. Furthermore, none of the cells analyzed expressing a CaR mutant in which the major PKC phosphorylation site Thr(888) was converted to alanine (CaRT888A) showed [Ca(2+)]i oscillations after CaR activation. Our results show that [Ca(2+)]i oscillations induced by activation of the CaR in response to an increase in extracellular Ca(2+) or exposure to the calcimimetic R-568 result from negative feedback involving PKCα-mediated phosphorylation of the CaR at Thr(888).
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Affiliation(s)
- Steven H Young
- Division of Digestive Diseases, Department of Medicine, Center for Ulcer Research and Education: Digestive Diseases Research Center David Geffen School of Medicine and Molecular Biology Institute, University of California, Los Angeles, California; and
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21
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Conigrave AD, Ward DT. Calcium-sensing receptor (CaSR): pharmacological properties and signaling pathways. Best Pract Res Clin Endocrinol Metab 2013; 27:315-31. [PMID: 23856262 DOI: 10.1016/j.beem.2013.05.010] [Citation(s) in RCA: 151] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
In this article we consider the mechanisms by which the calcium-sensing receptor (CaSR) induces its cellular responses via the control (activation or inhibition) of signaling pathways. We consider key features of CaSR-mediated signaling including its control of the heterotrimeric G-proteins Gq/11, Gi/o and G12/13 and the downstream consequences recognizing that very few CaSR-mediated cell phenomena have been fully described. We also consider the manner in which the CaSR contributes to the formation of specific signaling scaffolds via peptide recognition sequences in its intracellular C-terminal along with the origins of its high level of cooperativity, particularly for Ca(2+)o, and its remarkable resistance to desensitization. We also consider the nature of the mechanisms by which the CaSR controls oscillatory and sustained Ca(2+)i mobilizing responses and inhibits or elevates cyclic adenosine monophosphate (cAMP) levels dependent on the cellular and signaling context. Finally, we consider the diversity of the receptor's ligands, ligand binding sites and broader compartment-dependent physiological roles leading to the identification of pronounced ligand-biased signaling for agonists including Sr(2+) and modulators including l-amino acids and the clinically effective calcimimetic cinacalcet. We note the implications of these findings for the development of new designer drugs that might target the CaSR in pathophysiological contexts beyond those established for the treatment of disorders of calcium metabolism.
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Affiliation(s)
- Arthur D Conigrave
- School of Molecular Bioscience, University of Sydney, NSW 2006, Australia.
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22
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Breitwieser GE. The calcium sensing receptor life cycle: trafficking, cell surface expression, and degradation. Best Pract Res Clin Endocrinol Metab 2013; 27:303-13. [PMID: 23856261 DOI: 10.1016/j.beem.2013.03.003] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The calcium-sensing receptor (CaSR) must function in the chronic presence of agonist, and recent studies suggest that its ability to signal under such conditions depends upon the unique mechanism(s) regulating its cellular trafficking. This chapter will highlight the evidence supporting an intracellular endoplasmic reticulum-localized pool of CaSR that can be mobilized to the plasma membrane by CaSR signaling, leading to agonist-driven insertional signaling (ADIS). I summarize evidence for the role of small GTP binding proteins (Rabs, Sar1 and ARFs), cargo receptors or chaperones (p24A, RAMPs) and interacting proteins (14-3-3 proteins, calmodulin) in anterograde trafficking of CaSR, and discuss the potential signaling specializations arising from CaSR interactions with caveolins or Filamin A/Rho. Finally, I summarize current knowledge about CaSR endocytosis and degradation by both the proteasome and lysosome, and highlight recent studies indicating that defective trafficking of CaSR or interacting protein mutants contributes to pathology in disorders of calcium homeostasis.
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Affiliation(s)
- Gerda E Breitwieser
- Weis Center for Research, Geisinger Clinic, 100 N. Academy Avenue, Danville, PA 17822-2604, USA.
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Kopic S, Geibel JP. Gastric acid, calcium absorption, and their impact on bone health. Physiol Rev 2013; 93:189-268. [PMID: 23303909 DOI: 10.1152/physrev.00015.2012] [Citation(s) in RCA: 102] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Calcium balance is essential for a multitude of physiological processes, ranging from cell signaling to maintenance of bone health. Adequate intestinal absorption of calcium is a major factor for maintaining systemic calcium homeostasis. Recent observations indicate that a reduction of gastric acidity may impair effective calcium uptake through the intestine. This article reviews the physiology of gastric acid secretion, intestinal calcium absorption, and their respective neuroendocrine regulation and explores the physiological basis of a potential link between these individual systems.
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Affiliation(s)
- Sascha Kopic
- Department of Surgery and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut, USA
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24
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Calcium sensing receptor signalling in physiology and cancer. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1833:1732-44. [PMID: 23267858 DOI: 10.1016/j.bbamcr.2012.12.011] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2012] [Revised: 12/10/2012] [Accepted: 12/12/2012] [Indexed: 12/13/2022]
Abstract
The calcium sensing receptor (CaSR) is a class C G-protein-coupled receptor that is crucial for the feedback regulation of extracellular free ionised calcium homeostasis. While extracellular calcium (Ca(2+)o) is considered the primary physiological ligand, the CaSR is activated physiologically by a plethora of molecules including polyamines and l-amino acids. Activation of the CaSR by different ligands has the ability to stabilise unique conformations of the receptor, which may lead to preferential coupling of different G proteins; a phenomenon termed 'ligand-biased signalling'. While mutations of the CaSR are currently not linked with any malignancies, altered CaSR expression and function are associated with cancer progression. Interestingly, the CaSR appears to act both as a tumour suppressor and an oncogene, depending on the pathophysiology involved. Reduced expression of the CaSR occurs in both parathyroid and colon cancers, leading to loss of the growth suppressing effect of high Ca(2+)o. On the other hand, activation of the CaSR might facilitate metastasis to bone in breast and prostate cancer. A deeper understanding of the mechanisms driving CaSR signalling in different tissues, aided by a systems biology approach, will be instrumental in developing novel drugs that target the CaSR or its ligands in cancer. This article is part of a Special Issue entitled: 12th European Symposium on Calcium.
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Bradley SJ, Challiss RAJ. Defining protein kinase/phosphatase isoenzymic regulation of mGlu₅ receptor-stimulated phospholipase C and Ca²⁺ responses in astrocytes. Br J Pharmacol 2012; 164:755-71. [PMID: 21486279 DOI: 10.1111/j.1476-5381.2011.01421.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
BACKGROUND AND PURPOSE Cyclical phosphorylation and dephosphorylation of a key residue within the C-terminal domain of the activated type 5 metabotropic glutamate (mGlu₅) receptor is believed to cause the synchronous, oscillatory changes in inositol 1,4,5-trisphosphate and Ca²⁺ levels observed in a variety of cell types. Here, we have attempted to better define the kinase and phosphatase enzymes involved in this modulation. EXPERIMENTAL APPROACH Ca²⁺ and [³H]inositol phosphate ([³H]IP(x) ) measurements in astrocyte preparations have been used to evaluate the effects of pharmacological inhibition of protein kinase C (PKC) and protein phosphatase activities and small interfering RNA-mediated specific PKC isoenzymic knock-down on mGlu₅ receptor signalling. KEY RESULTS Ca²⁺ oscillation frequency or [³H]IP(x) accumulation in astrocytes stimulated by mGlu₅ receptors, was concentration-dependently decreased by protein phosphatase-1/2A inhibition or by PKC activation. PKC inhibition also increased [³H]IP(x) accumulation two- to threefold and changed the Ca²⁺ response into a peak-plateau response. However, selective inhibition of conventional PKC isoenzymes or preventing changes in [Ca²⁺](i) concentration by BAPTA-AM loading was without effect on mGlu₅ receptor-stimulated [³H]IP(x) accumulation. Selective knock-down of PKCδ was without effect on glutamate-stimulated Ca²⁺ responses; however, selective PKCε knock-down in astrocytes changed Ca²⁺ responses from oscillatory into peak-plateau type. CONCLUSION AND IMPLICATIONS These data confirm the acute regulation of mGlu₅ receptor signalling by protein kinases and protein phosphatases and provide novel data pinpointing the isoenzymic dependence of this regulation in the native mGlu₅ receptor-expressing rat cortical astrocyte. These data also highlight a potential alternative mechanism by which mGlu₅ receptor signalling might be therapeutically manipulated.
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Affiliation(s)
- S J Bradley
- Department of Cell Physiology and Pharmacology, University of Leicester, Leicester, UK
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26
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Bai SZ, Sun J, Wu H, Zhang N, Li HX, Li GW, Li HZ, He W, Zhang WH, Zhao YJ, Wang LN, Tian Y, Yang BF, Yang GD, Wu LY, Wang R, Xu CQ. Decrease in calcium-sensing receptor in the progress of diabetic cardiomyopathy. Diabetes Res Clin Pract 2012; 95:378-85. [PMID: 22137362 DOI: 10.1016/j.diabres.2011.11.007] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Revised: 10/31/2011] [Accepted: 11/07/2011] [Indexed: 02/06/2023]
Abstract
To observe the dynamic expression of calcium-sensing receptor (CaSR) in myocardium of diabetic rats and explore its role in diabetic cardiomyopathy (DCM), 40 male Wistar rats were randomly divided into 4 groups including control, diabetic-4 weeks, diabetic-8 weeks and spermine treatment groups (240 μM of spermine in drinking water). The type 2 Diabetes mellitus (DM) models were established by intraperitoneal injection of streptozotocin (STZ, 30 mg/kg) after high-fat and high-sugar diet for one month. The echocardiographic parameters were measured, cardiac morphology was observed by electron microscope and HE staining. The intracellular calcium concentration ([Ca(2+)](i)) was detected by laser-scanning confocal microscope. Western blot analyzed the expression of CaSR, protein kinase C α(PKC-α) and calcium handling regulators, such as phospholamban (PLN), Ca(2+)-ATPase (SERCA), and ryanodine receptor (RyR). Compared with control group, [Ca(2+)](i) and the expression of CaSR, RyR and SERCA/PLN were decreased, while PKC-α and PLN were significantly increased in a time-dependent manner in diabetic groups. Meanwhile diabetic rats displayed abnormal cardiac structure and systolic and diastolic dysfunction, and spermine (CaSR agonist) could prevent or slow its progression. These results indicate that the CaSR expression of myocardium is reduced in the progress of DCM, and its potential mechanism is related to the impaired intracellular calcium homeostasis.
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Affiliation(s)
- Shu-zhi Bai
- Department of Pathophysiology, Harbin Medical University, Harbin 150086, China
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27
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Huang Y, Cavanaugh A, Breitwieser GE. Regulation of stability and trafficking of calcium-sensing receptors by pharmacologic chaperones. ADVANCES IN PHARMACOLOGY 2012; 62:143-73. [PMID: 21907909 DOI: 10.1016/b978-0-12-385952-5.00007-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Gain- or loss-of-function mutations and polymorphisms of the calcium-sensing receptor (CaSR) cause Ca(2+) handling diseases. Altered expression and/or signaling of wild-type CaSR can also contribute to pathology. Recent studies have demonstrated that a significant proportion of mutations cause altered targeting and/or trafficking of CaSR to the plasma membrane. Pharmacological approaches to rescue of CaSR function include treatment with allosteric modulators, which potentiate the effects of the orthosteric agonist Ca(2+). Dissection of the mechanism(s) contributing to allosteric agonist-mediated rescue of loss-of-function CaSR mutants has demonstrated pharmacologic chaperone actions coincident with CaSR biosynthesis. The distinctive responses to the allosteric agonist (NPS R-568), which promotes CaSR stability, and the allosteric antagonist (NPS 2143), which promotes CaSR degradation, have led to a model for a conformational checkpoint during CaSR biosynthesis. The conformational checkpoint would "tune" CaSR biosynthesis to cellular signaling state. Navigation of a distinct checkpoint for endoplasmic release can also be augmented by pharmacologic chaperones. The diverse, post-endoplasmic reticulum quality control site(s) for pharmacologic chaperone modulation of CaSR stability and trafficking redefines the role(s) of allosteric modulators in regulation of overall GPCR function.
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Affiliation(s)
- Ying Huang
- Cancer Drug Research Laboratory, McGill University, Royal Victoria Hospital, Montreal, Quebec, Canada
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28
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Abstract
The calcium-sensing receptor (CaR) is the key controller of extracellular calcium (Ca(2+)(o)) homeostasis via its regulation of parathyroid hormone (PTH) secretion and renal Ca(2+) reabsorption. The CaR-selective calcimimetic drug Cinacalcet stimulates the CaR to suppress PTH secretion in chronic kidney disease and represents the world's first clinically available receptor positive allosteric modulator (PAM). Negative CaR allosteric modulators (NAMs), known as calcilytics, can increase PTH secretion and are being investigated as possible bone anabolic treatments against age-related osteoporosis. Here we address the current state of development and clinical use of a series of positive and negative CaR modulators. In addition, clinical CaR mutations and transgenic mice carrying tissue-specific CaR deletions have provided a novel understanding of the relative functional importance of CaR in both calciotropic tissues and those elsewhere in the body. The development of CaR-selective modulators and signalling reagents have provided us with a more detailed appreciation of how the CaR signals in vivo. Thus, both of these areas of CaR research will be reviewed.
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Affiliation(s)
- Donald T Ward
- Faculty of Life Sciences, The University of ManchesterManchester, UK
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29
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Signaling through the extracellular calcium-sensing receptor (CaSR). ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 740:103-42. [PMID: 22453940 DOI: 10.1007/978-94-007-2888-2_5] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The extracellular calcium ([Formula: see text])-sensing receptor (CaSR) was the first GPCR identified whose principal physiological ligand is an ion, namely extracellular Ca(2+). It maintains the near constancy of [Formula: see text] that complex organisms require to ensure normal cellular function. A wealth of information has accumulated over the past two decades about the CaSR's structure and function, its role in diseases and CaSR-based therapeutics. This review briefly describes the CaSR and key features of its structure and function, then discusses the extracellular signals modulating its activity, provides an overview of the intracellular signaling pathways that it controls, and, finally, briefly describes CaSR signaling both in tissues participating in [Formula: see text] homeostasis as well as those that do not. Factors controlling CaSR signaling include various factors affecting the expression of the CaSR gene as well as modulation of its trafficking to and from the cell surface. The dimeric cell surface CaSR, in turn, links to various heterotrimeric and small molecular weight G proteins to regulate intracellular second messengers, lipid kinases, various protein kinases, and transcription factors that are part of the machinery enabling the receptor to modulate the functions of the wide variety of cells in which it is expressed. CaSR signaling is impacted by its interactions with several binding partners in addition to signaling elements per se (i.e., G proteins), including filamin-A and caveolin-1. These latter two proteins act as scaffolds that bind signaling components and other key cellular elements (e.g., the cytoskeleton). Thus CaSR signaling likely does not take place randomly throughout the cell, but is compartmentalized and organized so as to facilitate the interaction of the receptor with its various signaling pathways.
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30
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The calcium-sensing receptor is necessary for the rapid development of hypercalcemia in human lung squamous cell carcinoma. Neoplasia 2011; 13:428-38. [PMID: 21532883 DOI: 10.1593/neo.101620] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2010] [Revised: 02/09/2011] [Accepted: 02/10/2011] [Indexed: 11/18/2022] Open
Abstract
The calcium-sensing receptor (CaR) is responsible for the regulation of extracellular calcium (Ca(2+) (o)) homeostasis. CaR activation has been shown to increase proliferation in several cancer cell lines; however, its presence or function has never been documented in lung cancer. We report that Ca(2+) (o)-activated CaR results in MAPK-mediated stimulation of parathyroid hormone-related protein (PTHrP) production in human lung squamous cell carcinoma (SCC) lines and humoral hypercalcemia of malignancy (HHM) in vivo. Furthermore, a single nucleotide polymorphism in CaR identified from a hypercalcemia-inducing lung SCC reduced the receptor's activation threshold leading to increased PTHrP expression and secretion. Increasing the expression of either wild-type CaR or a CaR variant with a single nucleotide polymorphism in the cytoplasmic domain was both necessary and sufficient for lung SCC to induce HHM. Because lung cancer patients who frequently develop HHM and PTHrP expression in lung cancer has been only partially explained, the significance of our findings indicates that CaR variants may provide a positive feedback between PTHrP and calcium and result in the syndrome of HHM.
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Abstract
Compelling evidence of a cell surface receptor sensitive to extracellular calcium was observed as early as the 1980s and was finally realized in 1993 when the calcium-sensing receptor (CaR) was cloned from bovine parathyroid tissue. Initial studies relating to the CaR focused on its key role in extracellular calcium homeostasis, but as the amount of information about the receptor grew it became evident that it was involved in many biological processes unrelated to calcium homeostasis. The CaR responds to a diverse array of stimuli extending well beyond that merely of calcium, and these stimuli can lead to the initiation of a wide variety of intracellular signaling pathways that in turn are able to regulate a diverse range of biological processes. It has been through the examination of the molecular characteristics of the CaR that we now have an understanding of how this single receptor is able to convert extracellular messages into specific cellular responses. Recent CaR-related reviews have focused on specific aspects of the receptor, generally in the context of the CaR's role in physiology and pathophysiology. This review will provide a comprehensive exploration of the different aspects of the receptor, including its structure, stimuli, signalling, interacting protein partners, and tissue expression patterns, and will relate their impact on the functionality of the CaR from a molecular perspective.
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Affiliation(s)
- Aaron L Magno
- Department of Endocrinology and Diabetes, First Floor, C Block, Sir Charles Gairdner Hospital, Hospital Avenue, Nedlands 6009, Western Australia, Australia
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32
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Huang Y, Zhou Y, Wong HC, Castiblanco A, Chen Y, Brown EM, Yang JJ. Calmodulin regulates Ca2+-sensing receptor-mediated Ca2+ signaling and its cell surface expression. J Biol Chem 2010; 285:35919-31. [PMID: 20826781 DOI: 10.1074/jbc.m110.147918] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The Ca(2+)-sensing receptor (CaSR) is a member of family C of the GPCRs responsible for sensing extracellular Ca(2+) ([Ca(2+)](o)) levels, maintaining extracellular Ca(2+) homeostasis, and transducing Ca(2+) signaling from the extracellular milieu to the intracellular environment. In the present study, we have demonstrated a Ca(2+)-dependent, stoichiometric interaction between CaM and a CaM-binding domain (CaMBD) located within the C terminus of CaSR (residues 871-898). Our studies suggest a wrapping around 1-14-like mode of interaction that involves global conformational changes in both lobes of CaM with concomitant formation of a helical structure in the CaMBD. More importantly, the Ca(2+)-dependent association between CaM and the C terminus of CaSR is critical for maintaining proper responsiveness of intracellular Ca(2+) responses to changes in extracellular Ca(2+) and regulating cell surface expression of the receptor.
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Affiliation(s)
- Yun Huang
- Department of Chemistry, Center for Drug Design and Advanced Biotechnology, Georgia State University, Atlanta, Georgia 30303, USA
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33
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McCormick WD, Atkinson-Dell R, Campion KL, Mun HC, Conigrave AD, Ward DT. Increased receptor stimulation elicits differential calcium-sensing receptor(T888) dephosphorylation. J Biol Chem 2010; 285:14170-7. [PMID: 20233724 DOI: 10.1074/jbc.m109.071084] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The calcium-sensing receptor (CaR) elicits oscillatory Ca(2+)(i) mobilization associated with dynamic, inhibitory protein kinase C-mediated phosphorylation of CaR(T888). While modest CaR stimulation elicits Ca(2+)(i) oscillations, greater stimulation either increases oscillation frequency or elicits sustained responses by an unknown mechanism. Here, moderate CaR stimulation (2.5 mm Ca(2+)(o), 10 min) increased CaR(T888) phosphorylation (160-kDa mature receptor) 5-fold in CaR stably transfected HEK-293 cells, whereas 3-5 mm Ca(2+)(o) treatments were without apparent effect. Treatment with 2 mm Ca(2+)(o) caused sustained CaR(T888) phosphorylation (> or = 20 min) and oscillatory Ca(2+)(i) mobilization. However, 5 mm Ca(2+)(o) increased CaR(T888) phosphorylation only briefly while eliciting sustained Ca(2+)(i) mobilization, suggesting that greater CaR activation induces rapid CaR(T888) dephosphorylation, thus permitting sustained Ca(2+)(i) responses. Indeed, 5 mm Ca(2+)(o) stimulated protein phosphatase 2A activity and induced CaR(T888) dephosphorylation following acute phorbol ester pretreatment, the latter effect being mimicked by CaR-positive allosteric modulators (NPS-R467 and l-Phe). Finally, the phosphatase inhibitor calyculin-A reversed CaR-induced inhibition of parathyroid hormone secretion from bovine parathyroid slices and normal human parathyroid cells, demonstrating the physiological importance of phosphorylation status on parathyroid function. Therefore, high Ca(2+)(o)-stimulated protein kinase C acts in concert with high Ca(2+)(o)-induced phosphatase activity to generate and maintain CaR-induced Ca(2+)(i) oscillations via the dynamic phosphorylation and dephosphorylation of CaR(T888).
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Affiliation(s)
- Wanda D McCormick
- Faculty of Life Sciences, The University of Manchester, Manchester M13 9NT, United Kingdom
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34
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Khan MA, Conigrave AD. Mechanisms of multimodal sensing by extracellular Ca(2+)-sensing receptors: a domain-based survey of requirements for binding and signalling. Br J Pharmacol 2010; 159:1039-50. [PMID: 20136834 DOI: 10.1111/j.1476-5381.2009.00603.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
In this article we consider the molecular basis of sensing and signalling by the extracellular calcium-sensing receptor. We consider the nature of its ligands and sensing modalities, the identities of its major protein domains and their roles in sensing, signalling and trafficking as well as the significance of receptor homo- and hetero-dimerization. Finally, we consider the current, incomplete, state of knowledge regarding the requirements for ligand-specific signalling.
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35
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Topala CN, Schoeber JPH, Searchfield LE, Riccardi D, Hoenderop JGJ, Bindels RJM. Activation of the Ca2+-sensing receptor stimulates the activity of the epithelial Ca2+ channel TRPV5. Cell Calcium 2009; 45:331-9. [PMID: 19157541 DOI: 10.1016/j.ceca.2008.12.003] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2008] [Revised: 12/09/2008] [Accepted: 12/10/2008] [Indexed: 10/21/2022]
Abstract
The extracellular Ca(2+)-sensing receptor (CaR) is a key-player in plasma Ca(2+) homeostasis. It is essentially expressed in the parathyroid glands and along the kidney nephron. The distal convoluted tubules (DCT) and connecting tubules (CNT) in the kidney are involved in active Ca(2+) reabsorption, but the function of the CaR has remained unclear in these segments. Here, the Ca(2+)-selective Transient Receptor Potential Vanilloid-subtype 5 channel (TRPV5) determines active Ca(2+) reabsorption by forming the apical entry gate. In this study we show that the CaR and TRPV5 co-localize at the luminal membrane of DCT/CNT. Furthermore, by patch-clamp and Fura-2-ratiometric measurements we demonstrate that activation of the CaR leads to elevated TRPV5-mediated currents and increases intracellular Ca(2+) concentrations in cells co-expressing TRPV5 and CaR. Activation of CaR initiated a signaling cascade that activated phorbol-12-myristate-13-acetate (PMA)-insensitive protein kinase C (PKC) isoforms. Importantly, mutation of two putative PKC phosphorylation sites, S299 and S654, in TRPV5 prevented the stimulatory effect of CaR activation on channel activity, as did a dominant negative CaR construct, CaR(R185Q). Interestingly, the activity of TRPV6, TRPV5' closest homologue, was not affected by the activated CaR. We conclude that activation of the CaR stimulates TRPV5-mediated Ca(2+) influx via a PMA-insensitive PKC isoform pathway.
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Affiliation(s)
- Catalin N Topala
- Department of Physiology, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
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36
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Davies SL, Gibbons CE, Steward MC, Ward DT. Extracellular calcium- and magnesium-mediated regulation of passive calcium transport across Caco-2 monolayers. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1778:2318-24. [DOI: 10.1016/j.bbamem.2008.05.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2008] [Revised: 05/28/2008] [Accepted: 05/29/2008] [Indexed: 01/09/2023]
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37
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Mamillapalli R, VanHouten J, Zawalich W, Wysolmerski J. Switching of G-protein usage by the calcium-sensing receptor reverses its effect on parathyroid hormone-related protein secretion in normal versus malignant breast cells. J Biol Chem 2008; 283:24435-47. [PMID: 18621740 PMCID: PMC2528989 DOI: 10.1074/jbc.m801738200] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2008] [Revised: 05/26/2008] [Indexed: 12/20/2022] Open
Abstract
The calcium-sensing receptor (CaR) is a G-protein-coupled receptor that signals in response to extracellular calcium and regulates parathyroid hormone secretion. The CaR is also expressed on normal mammary epithelial cells (MMECs), where it has been shown to inhibit secretion of parathyroid hormone-related protein (PTHrP) and participate in the regulation of calcium and bone metabolism during lactation. In contrast to normal breast cells, the CaR has been reported to stimulate PTHrP production by breast cancer cells. In this study, we confirmed that the CaR inhibits PTHrP production by MMECs but stimulates PTHrP production by Comma-D cells (immortalized murine mammary cells) and MCF-7 human breast cancer cells. We found that changes in intracellular cAMP, but not phospholipase C or MAPK signaling, correlated with the opposing effects of the CaR on PTHrP production. Pharmacologic stimulation of cAMP accumulation increased PTHrP production by normal and transformed breast cells. Inhibition of protein kinase A activity mimicked the effects of CaR activation on inhibiting PTHrP secretion by MMECs and blocked the effects of the CaR on stimulating PTHrP production in Comma-D and MCF-7 cells. We found that the CaR coupled to Galphai in MMECs but coupled to Galphas in Comma-D and MCF-7 cells. Thus, the opposing effects of the CaR on PTHrP production are because of alternate G-protein coupling of the receptor in normal versus transformed breast cells. Because PTHrP contributes to hypercalcemia and bone metastases, switching of G-protein usage by the CaR may contribute to the pathogenesis of breast cancer.
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Affiliation(s)
- Ramanaiah Mamillapalli
- Section of Endocrinology and Metabolism,
Department of Internal Medicine, School of Medicine and
School of Nursing, Yale University, New Haven,
Connecticut 06520
| | - Joshua VanHouten
- Section of Endocrinology and Metabolism,
Department of Internal Medicine, School of Medicine and
School of Nursing, Yale University, New Haven,
Connecticut 06520
| | - Walter Zawalich
- Section of Endocrinology and Metabolism,
Department of Internal Medicine, School of Medicine and
School of Nursing, Yale University, New Haven,
Connecticut 06520
| | - John Wysolmerski
- Section of Endocrinology and Metabolism,
Department of Internal Medicine, School of Medicine and
School of Nursing, Yale University, New Haven,
Connecticut 06520
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38
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Extracellular calcium-sensing receptors in fishes. Comp Biochem Physiol A Mol Integr Physiol 2008; 149:225-45. [DOI: 10.1016/j.cbpa.2008.01.037] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2007] [Revised: 01/23/2008] [Accepted: 01/23/2008] [Indexed: 11/19/2022]
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Calcium-sensing receptor antagonism or lithium treatment ameliorates aminoglycoside-induced cell death in renal epithelial cells. Biochim Biophys Acta Mol Basis Dis 2008; 1782:188-95. [PMID: 18261471 DOI: 10.1016/j.bbadis.2008.01.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2007] [Revised: 01/07/2008] [Accepted: 01/08/2008] [Indexed: 11/21/2022]
Abstract
The aminoglycoside antibiotic gentamicin elicits proximal tubular toxicity and cell death. In calcium-sensing receptor (CaR)-transfected HEK-293 (CaR-HEK) cells and CaR-expressing proximal tubule-derived opossum kidney (OK) cells, chronic gentamicin treatment elicits dose-dependent, caspase-mediated apoptotic cell death. Here we investigated whether the renal cell toxicity of the CaR agonist gentamicin could be prevented by CaR antagonism or by lithium cotreatment which may interfere with receptor-mediated signalling. Chronic treatment of OK and CaR-HEK cells with low concentrations of gentamicin elicited cell death, an effect that was ameliorated by cotreatment with the CaR negative allosteric modulator (calcilytic) NPS-89636. This calcilytic also attenuated CaR agonist-induced ERK activation in these cells. In addition, 1 mM LiCl, equivalent to its therapeutic plasma concentration, also inhibited gentamicin-induced toxicity in both cell types. This protective effect of lithium was not due to the disruption of phosphatidylinositol-mediated gentamicin uptake as the cellular entry of Texas red-conjugated gentamicin into OK and CaR-HEK cells was unchanged by lithium treatment. However, the protective effect of lithium was mimicked by glycogen synthase 3beta inhibition. Together, these data implicate CaR activation and a lithium-inhibitable signalling pathway in the induction of cell death by gentamicin in renal epithelial cells in culture.
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