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Tian L, Andrews C, Yan Q, Yang JJ. Molecular regulation of calcium-sensing receptor (CaSR)-mediated signaling. Chronic Dis Transl Med 2024; 10:167-194. [PMID: 39027195 PMCID: PMC11252437 DOI: 10.1002/cdt3.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Revised: 03/29/2024] [Accepted: 04/09/2024] [Indexed: 07/20/2024] Open
Abstract
Calcium-sensing receptor (CaSR), a family C G-protein-coupled receptor, plays a crucial role in regulating calcium homeostasis by sensing small concentration changes of extracellular Ca2+, Mg2+, amino acids (e.g., L-Trp and L-Phe), small peptides, anions (e.g., HCO3 - and PO4 3-), and pH. CaSR-mediated intracellular Ca2+ signaling regulates a diverse set of cellular processes including gene transcription, cell proliferation, differentiation, apoptosis, muscle contraction, and neuronal transmission. Dysfunction of CaSR with mutations results in diseases such as autosomal dominant hypocalcemia, familial hypocalciuric hypercalcemia, and neonatal severe hyperparathyroidism. CaSR also influences calciotropic disorders, such as osteoporosis, and noncalciotropic disorders, such as cancer, Alzheimer's disease, and pulmonary arterial hypertension. This study first reviews recent advances in biochemical and structural determination of the framework of CaSR and its interaction sites with natural ligands, as well as exogenous positive allosteric modulators and negative allosteric modulators. The establishment of the first CaSR protein-protein interactome network revealed 94 novel players involved in protein processing in endoplasmic reticulum, trafficking, cell surface expression, endocytosis, degradation, and signaling pathways. The roles of these proteins in Ca2+-dependent cellular physiological processes and in CaSR-dependent cellular signaling provide new insights into the molecular basis of diseases caused by CaSR mutations and dysregulated CaSR activity caused by its protein interactors and facilitate the design of therapeutic agents that target CaSR and other family C G-protein-coupled receptors.
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Affiliation(s)
- Li Tian
- Department of Chemistry, Center for Diagnostics and Therapeutics, Advanced Translational Imaging FacilityGeorgia State UniversityAtlantaGeorgiaUSA
| | - Corey Andrews
- Department of Chemistry, Center for Diagnostics and Therapeutics, Advanced Translational Imaging FacilityGeorgia State UniversityAtlantaGeorgiaUSA
| | - Qiuyun Yan
- Department of Chemistry, Center for Diagnostics and Therapeutics, Advanced Translational Imaging FacilityGeorgia State UniversityAtlantaGeorgiaUSA
| | - Jenny J. Yang
- Department of Chemistry, Center for Diagnostics and Therapeutics, Advanced Translational Imaging FacilityGeorgia State UniversityAtlantaGeorgiaUSA
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Whitfield JF, Rennie K, Chakravarthy B. Alzheimer's Disease and Its Possible Evolutionary Origin: Hypothesis. Cells 2023; 12:1618. [PMID: 37371088 DOI: 10.3390/cells12121618] [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: 04/01/2023] [Revised: 05/29/2023] [Accepted: 06/08/2023] [Indexed: 06/29/2023] Open
Abstract
The enormous, 2-3-million-year evolutionary expansion of hominin neocortices to the current enormity enabled humans to take over the planet. However, there appears to have been a glitch, and it occurred without a compensatory expansion of the entorhinal cortical (EC) gateway to the hippocampal memory-encoding system needed to manage the processing of the increasing volume of neocortical data converging on it. The resulting age-dependent connectopathic glitch was unnoticed by the early short-lived populations. It has now surfaced as Alzheimer's disease (AD) in today's long-lived populations. With advancing age, processing of the converging neocortical data by the neurons of the relatively small lateral entorhinal cortex (LEC) inflicts persistent strain and high energy costs on these cells. This may result in their hyper-release of harmless Aβ1-42 monomers into the interstitial fluid, where they seed the formation of toxic amyloid-β oligomers (AβOs) that initiate AD. At the core of connectopathic AD are the postsynaptic cellular prion protein (PrPC). Electrostatic binding of the negatively charged AβOs to the positively charged N-terminus of PrPC induces hyperphosphorylation of tau that destroys synapses. The spread of these accumulating AβOs from ground zero is supported by Aβ's own production mediated by target cells' Ca2+-sensing receptors (CaSRs). These data suggest that an early administration of a strongly positively charged, AβOs-interacting peptide or protein, plus an inhibitor of CaSR, might be an effective AD-arresting therapeutic combination.
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Affiliation(s)
- James F Whitfield
- Human Health Therapeutics, National Research Council, Ottawa, ON K1A 0R6, Canada
| | - Kerry Rennie
- Human Health Therapeutics, National Research Council, Ottawa, ON K1A 0R6, Canada
| | - Balu Chakravarthy
- Human Health Therapeutics, National Research Council, Ottawa, ON K1A 0R6, Canada
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Werner LE, Wagner U. Calcium-sensing receptor-mediated NLRP3 inflammasome activation in rheumatoid arthritis and autoinflammation. Front Physiol 2023; 13:1078569. [PMID: 36685206 PMCID: PMC9854345 DOI: 10.3389/fphys.2022.1078569] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Accepted: 11/17/2022] [Indexed: 01/09/2023] Open
Abstract
The calcium-sensing receptor (CaSR) is expressed in many cell types - including immune cells and in particular circulating monocytes. Here, the receptor plays an important physiological role as a regulator of constitutive macropinocytosis. This review article provides an overview of the literature on the role of the calcium sensing receptor in the context of inflammatory processes. Special emphasis is laid upon the importance for monocytes in the context of rheumatoid arthritis. We have shown previously, that stimulation of the receptor by increased extracellular Ca2+ ([Ca2+]ex) triggers a pro-inflammatory response due to NLRP3 inflammasome assembly and interleukin (IL)-1β release. The underlying mechanism includes macropinocytosis of calciprotein particles (CPPs), which are taken up in a [Ca2+]ex-induced, CaSR dependent manner, and leads to strong IL-1β release. In rheumatoid arthritis (RA), this uptake and the resulting IL-1β release is significantly increased due to increased expression of the receptor. Moreover, increased [Ca2+]ex-induced CPP uptake and IL-1β release is associated with more active disease, while CaSR overexpression has been reported to be associated with cardiovascular complications of RA. Most importantly, however, in animal experiments with arthritic mice, increased local calcium concentrations are present, which in combination with release of fetuin-A from eroded bone could contribute to formation of CPPs. We propose, that increased [Ca2+]ex, CPPs and pro-inflammatory cytokines drive a vicious cycle of inflammation and bone destruction which in turn offers new potential therapeutic approaches.
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Wang X, Lundblad J, Smith SM. Reduced affinity of calcium sensing-receptor heterodimers and reduced mutant homodimer trafficking combine to impair function in a model of familial hypocalciuric hypercalcemia type 1. PLoS One 2022; 17:e0266993. [PMID: 35857775 PMCID: PMC9299317 DOI: 10.1371/journal.pone.0266993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 06/30/2022] [Indexed: 11/18/2022] Open
Abstract
Heterozygous loss-of-function mutation of the calcium sensing-receptor (CaSR), causes familial hypocalciuric hypercalcemia type 1 (FHH1), a typically benign condition characterized by mild hypercalcemia. In contrast, homozygous mutation of this dimer-forming G-protein coupled receptor manifests as the lethal neonatal severe hyperparathyroidism (NSHPT). To investigate the mechanisms by which CaSR mutations lead to these distinct disease states, we engineered wild-type (WT) and an exon 5-deficient disease-causing mutation, and transfected expression constructs into human embryonic kidney (HEK) cells. WT protein was mainly membrane-expressed whereas the mutant CaSR protein (mCaSR) was confined to the cytoplasm. Co-expression of WT CaSR directed mCaSR to the cell membrane. In assays of CaSR function, increases in extracellular [Ca2+] ([Ca2+]o) increased intracellular [Ca2+] ([Ca2+]i) in cells expressing WT CaSR while the response was reduced in cells co-expressing mutant and WT receptor. Untransfected cells or those expressing mCaSR alone, showed minimal, equivalent responses to increased [Ca2+]o. Immunoprecipitation experiments confirmed an association between mutant and wild-type CaSR. The affinity of the WT CaSR for calcium was three times greater than that of the heterodimer. The maximal functional response to [Ca]o was dependent on localization of CaSR to the membrane level and independent of homo- or heterodimerizations. In summary, these results suggest that heterodimerization of WT and mCaSR receptors, rescues the trafficking defect of the mutant receptors and also reduces the affinity of the WT-mutant heterodimer for [Ca]o. In contrast, the homozygous mutants do not produce functional receptors on cell membrane. These data indicate how substantial differences between signaling of hetero- and homodimeric mutants may lead to profound differences in the severity of disease in heterozygous and homozygous carriers of these mutations.
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Affiliation(s)
- Xiaohua Wang
- Division of Pulmonary and Critical Care Medicine, Oregon Health and Science University, Portland, Oregon, United States of America
| | - James Lundblad
- Division of Endocrinology and Diabetes, Oregon Health and Science University, Portland, Oregon, United States of America
- Section of Endocrinology and Diabetes, VA Portland Health Care System, Portland, Oregon, United States of America
| | - Stephen M. Smith
- Division of Pulmonary and Critical Care Medicine, Oregon Health and Science University, Portland, Oregon, United States of America
- Sections of Pulmonary and Critical Care Medicine and Research & Development, VA Portland Health Care System, Portland, Oregon, United States of America
- * E-mail:
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Tsentsevitsky AN, Khaziev EF, Kovyazina IV, Petrov AM. GIRK channel as a versatile regulator of neurotransmitter release via L-type Ca 2+ channel-dependent mechanism in the neuromuscular junction. Neuropharmacology 2022; 209:109021. [PMID: 35245509 DOI: 10.1016/j.neuropharm.2022.109021] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 02/14/2022] [Accepted: 02/25/2022] [Indexed: 01/04/2023]
Abstract
G protein-gated inwardly rectifying potassium (GIRK) channels are one of the main regulators of neuronal excitability. Activation of GIRK channels in the CNS usually leads to postsynaptic inhibition. However, the function of GIRK channels in the presynaptic processes, notably neurotransmitter release form motor nerve terminals, is yet to be comprehensively understood. Here, using electrophysiological and fluorescent approaches, the role of GIRK channels in neurotransmitter release from frog motor nerve terminals was studied. We found that the inhibition of GIRK channels with nanomolar tertiapin-Q synchronized exocytosis events with action potential but suppressed spontaneous and evoked neurotransmitter release, as well as Ca2+ transient and membrane permeability for K+. The action of GIRK channel inhibition on evoked neurotransmission was prevented by selective antagonist of voltage-gated Ca2+ channels of L-type. Furthermore, the effects of muscarinic acetylcholine receptor activation on neurotransmitter release, Ca2+ transient and K+ channel activity were markedly modulated by inhibition of GIRK channels. Thus, at the motor nerve terminals GIRK channels can regulate timing of neurotransmitter release and be a positive modulator of synaptic vesicle exocytosis acting partially via L-type Ca2+ channels. In addition, GIRK channels are key players in a feedback control of neurotransmitter release by muscarinic acetylcholine receptors.
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Affiliation(s)
- Andrei N Tsentsevitsky
- Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, FRC "Kazan Scientific Center of RAS", P.o. Box 30, 420111, Kazan, Russia
| | - Eduard F Khaziev
- Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, FRC "Kazan Scientific Center of RAS", P.o. Box 30, 420111, Kazan, Russia
| | - Irina V Kovyazina
- Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, FRC "Kazan Scientific Center of RAS", P.o. Box 30, 420111, Kazan, Russia; Kazan State Medical University, Butlerov St., 49, 420008, Kazan, Russia.
| | - Alexey M Petrov
- Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, FRC "Kazan Scientific Center of RAS", P.o. Box 30, 420111, Kazan, Russia; Kazan State Medical University, Butlerov St., 49, 420008, Kazan, Russia
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6
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Zhang Q, Zhang LJ, Yuan SS, Quan XJ, Zhang BY, Zhao D. Hypoparathyroidism Associated with the DNA Variants in Non-Coding Sequence Region of Calcium-Sensing Receptor. ENDOCRINE AND METABOLIC SCIENCE 2021. [DOI: 10.1016/j.endmts.2021.100106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Salinity-dependent expression of calcium-sensing receptors in Atlantic salmon (Salmo salar) tissues. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2021; 207:505-522. [PMID: 34114081 DOI: 10.1007/s00359-021-01493-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 05/23/2021] [Accepted: 05/26/2021] [Indexed: 10/21/2022]
Abstract
Multiple reports suggest that calcium-sensing receptors (CaSRs) are involved in calcium homeostasis, osmoregulation, and/or salinity sensing in fish (Loretz 2008, Herberger and Loretz 2013). We have isolated three unique full-length CaSR cDNAs from Atlantic salmon (Salmo salar) kidney that share many features with other reported CaSRs. Using anti-CaSR antibodies and PCR primers specific for individual salmon CaSR transcripts we show expression in osmoregulatory, neuroendocrine and sensory tissues. Furthermore, CaSRs are expressed in different patterns in salmon tissues where mRNA and protein expression are modified by freshwater or seawater acclimation. For example, in seawater, CaSR mRNA and protein expression is increased significantly in kidney as compared to freshwater. Electrophysiological recordings of olfactory responses produced upon exposure of salmon olfactory epithelium to CaSR agonists suggest a role for CaSRs in chemoreception in this species consistent with other freshwater, anadromous, and marine species where similar olfactory responses to divalent and polyvalent cations have been reported. These data provide further support for a role of CaSR proteins in osmoregulatory and sensory functions in Atlantic salmon, an anadromous species that experiences a broad range of environmental salinities in its life history.
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Sundararaman SS, van der Vorst EPC. Calcium-Sensing Receptor (CaSR), Its Impact on Inflammation and the Consequences on Cardiovascular Health. Int J Mol Sci 2021; 22:2478. [PMID: 33804544 PMCID: PMC7957814 DOI: 10.3390/ijms22052478] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Revised: 02/11/2021] [Accepted: 02/25/2021] [Indexed: 12/15/2022] Open
Abstract
The calcium Sensing Receptor (CaSR) is a cell surface receptor belonging to the family of G-protein coupled receptors. CaSR is mainly expressed by parathyroid glands, kidneys, bone, skin, adipose tissue, the gut, the nervous system, and the cardiovascular system. The receptor, as its name implies is involved in sensing calcium fluctuations in the extracellular matrix of cells, thereby having a major impact on the mineral homeostasis in humans. Besides calcium ions, the receptor is also activated by other di- and tri-valent cations, polypeptides, polyamines, antibiotics, calcilytics and calcimimetics, which upon binding induce intracellular signaling pathways. Recent studies have demonstrated that CaSR influences a wide variety of cells and processes that are involved in inflammation, the cardiovascular system, such as vascular calcification, atherosclerosis, myocardial infarction, hypertension, and obesity. Therefore, in this review, the current understanding of the role that CaSR plays in inflammation and its consequences on the cardiovascular system will be highlighted.
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Affiliation(s)
- Sai Sahana Sundararaman
- Interdisciplinary Centre for Clinical Research (IZKF), RWTH Aachen University, 52074 Aachen, Germany;
- Institute for Molecular Cardiovascular Research (IMCAR), RWTH Aachen University, 52074 Aachen, Germany
| | - Emiel P. C. van der Vorst
- Interdisciplinary Centre for Clinical Research (IZKF), RWTH Aachen University, 52074 Aachen, Germany;
- Institute for Molecular Cardiovascular Research (IMCAR), RWTH Aachen University, 52074 Aachen, Germany
- Department of Pathology, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University Medical Centre, 6229 ER Maastricht, The Netherlands
- Institute for Cardiovascular Prevention (IPEK), Ludwig-Maximilians-University Munich, 80336 Munich, Germany
- German Centre for Cardiovascular Research (DZHK), partner site Munich Heart Alliance, 80336 Munich, Germany
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10
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Mechanisms and Regulation of Neuronal GABA B Receptor-Dependent Signaling. Curr Top Behav Neurosci 2020; 52:39-79. [PMID: 32808092 DOI: 10.1007/7854_2020_129] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
γ-Aminobutyric acid B receptors (GABABRs) are broadly expressed throughout the central nervous system where they play an important role in regulating neuronal excitability and synaptic transmission. GABABRs are G protein-coupled receptors that mediate slow and sustained inhibitory actions via modulation of several downstream effector enzymes and ion channels. GABABRs are obligate heterodimers that associate with diverse arrays of proteins to form modular complexes that carry out distinct physiological functions. GABABR-dependent signaling is fine-tuned and regulated through a multitude of mechanisms that are relevant to physiological and pathophysiological states. This review summarizes the current knowledge on GABABR signal transduction and discusses key factors that influence the strength and sensitivity of GABABR-dependent signaling in neurons.
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Wang M, Xia F, Wei Y, Wei X. Molecular mechanisms and clinical management of cancer bone metastasis. Bone Res 2020; 8:30. [PMID: 32793401 PMCID: PMC7391760 DOI: 10.1038/s41413-020-00105-1] [Citation(s) in RCA: 76] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 09/03/2019] [Accepted: 10/23/2019] [Indexed: 02/05/2023] Open
Abstract
As one of the most common metastatic sites of malignancies, bone has a unique microenvironment that allows metastatic tumor cells to grow and flourish. The fenestrated capillaries in the bone, bone matrix, and bone cells, including osteoblasts and osteoclasts, together maintain the homeostasis of the bone microenvironment. In contrast, tumor-derived factors act on bone components, leading to subsequent bone resorption or excessive bone formation. The various pathways involved also provide multiple targets for therapeutic strategies against bone metastases. In this review, we summarize the current understanding of the mechanism of bone metastases. Based on the general process of bone metastases, we specifically highlight the complex crosstalk between tumor cells and the bone microenvironment and the current management of cancer bone metastases.
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Affiliation(s)
- Manni Wang
- Laboratory of Aging Research and Cancer Drug Targets, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, No. 17, Block 3, Southern Renmin Road, Chengdu, 610041 Sichuan P.R. China
| | - Fan Xia
- Department of Neurosurgery, West China Hospital, Sichuan University, Chengdu, 610041 Sichuan P.R. China
| | - Yuquan Wei
- Laboratory of Aging Research and Cancer Drug Targets, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, No. 17, Block 3, Southern Renmin Road, Chengdu, 610041 Sichuan P.R. China
| | - Xiawei Wei
- Laboratory of Aging Research and Cancer Drug Targets, State Key Laboratory of Biotherapy and Cancer Center, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, No. 17, Block 3, Southern Renmin Road, Chengdu, 610041 Sichuan P.R. China
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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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13
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Chang W, Tu CL, Jean-Alphonse FG, Herberger A, Cheng Z, Hwong J, Ho H, Li A, Wang D, Liu H, White AD, Suh I, Shen W, Duh QY, Khanafshar E, Shoback DM, Xiao K, Vilardaga JP. PTH hypersecretion triggered by a GABA B1 and Ca 2+-sensing receptor heterocomplex in hyperparathyroidism. Nat Metab 2020; 2:243-255. [PMID: 32694772 PMCID: PMC7377265 DOI: 10.1038/s42255-020-0175-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 01/20/2020] [Indexed: 12/14/2022]
Abstract
Molecular mechanisms mediating tonic secretion of parathyroid hormone (PTH) in response to hypocalcaemia and hyperparathyroidism (HPT) are unclear. Here we demonstrate increased heterocomplex formation between the calcium-sensing receptor (CaSR) and metabotropic γ-aminobutyric acid (GABA) B1 receptor (GABAB1R) in hyperplastic parathyroid glands (PTGs) of patients with primary and secondary HPT. Targeted ablation of GABAB1R or glutamic acid decarboxylase 1 and 2 in PTGs produces hypocalcaemia and hypoparathyroidism, and prevents PTH hypersecretion in PTGs cultured from mouse models of hereditary HPT and dietary calcium-deficiency. Cobinding of the CaSR/GABAB1R complex by baclofen and high extracellular calcium blocks the coupling of heterotrimeric G-proteins to homomeric CaSRs in cultured cells and promotes PTH secretion in cultured mouse PTGs. These results combined with the ability of PTG to synthesize GABA support a critical autocrine action of GABA/GABAB1R in mediating tonic PTH secretion of PTGs and ascribe aberrant activities of CaSR/GABAB1R heteromer to HPT.
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Affiliation(s)
- Wenhan Chang
- Endocrine Research Unit, Department of Veterans Affairs Medical Center, University of California, San Francisco, CA, USA.
| | - Chia-Ling Tu
- Endocrine Research Unit, Department of Veterans Affairs Medical Center, University of California, San Francisco, CA, USA
| | - Frederic G Jean-Alphonse
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Amanda Herberger
- Endocrine Research Unit, Department of Veterans Affairs Medical Center, University of California, San Francisco, CA, USA
| | - Zhiqiang Cheng
- Endocrine Research Unit, Department of Veterans Affairs Medical Center, University of California, San Francisco, CA, USA
| | - Jenna Hwong
- Endocrine Research Unit, Department of Veterans Affairs Medical Center, University of California, San Francisco, CA, USA
| | - Hanson Ho
- Endocrine Research Unit, Department of Veterans Affairs Medical Center, University of California, San Francisco, CA, USA
| | - Alfred Li
- Endocrine Research Unit, Department of Veterans Affairs Medical Center, University of California, San Francisco, CA, USA
| | - Dawei Wang
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Hongda Liu
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Alex D White
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Graduate Program in Molecular Pharmacology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Insoo Suh
- Department of Surgery, University of California, San Francisco, CA, USA
| | - Wen Shen
- Department of Surgery, University of California, San Francisco, CA, USA
| | - Quan-Yang Duh
- Department of Surgery, University of California, San Francisco, CA, USA
| | - Elham Khanafshar
- Department of Pathology, University of California, San Francisco, CA, USA
| | - Dolores M Shoback
- Endocrine Research Unit, Department of Veterans Affairs Medical Center, University of California, San Francisco, CA, USA
| | - Kunhong Xiao
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Jean-Pierre Vilardaga
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
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14
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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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15
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Dal Prà I, Armato U, Chiarini A. Family C G-Protein-Coupled Receptors in Alzheimer's Disease and Therapeutic Implications. Front Pharmacol 2019; 10:1282. [PMID: 31719824 PMCID: PMC6826475 DOI: 10.3389/fphar.2019.01282] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 10/07/2019] [Indexed: 12/12/2022] Open
Abstract
Alzheimer’s disease (AD), particularly its sporadic or late-onset form (SAD/LOAD), is the most prevalent (96–98% of cases) neurodegenerative dementia in aged people. AD’s neuropathology hallmarks are intrabrain accumulation of amyloid-β peptides (Aβs) and of hyperphosphorylated Tau (p-Tau) proteins, diffuse neuroinflammation, and progressive death of neurons and oligodendrocytes. Mounting evidences suggest that family C G-protein-coupled receptors (GPCRs), which include γ-aminobutyric acid B receptors (GABABRs), metabotropic glutamate receptors (mGluR1-8), and the calcium-sensing receptor (CaSR), are involved in many neurotransmitter systems that dysfunction in AD. This review updates the available knowledge about the roles of GPCRs, particularly but not exclusively those expressed by brain astrocytes, in SAD/LOAD onset and progression, taking stock of their respective mechanisms of action and of their potential as anti-AD therapeutic targets. In particular, GABABRs prevent Aβs synthesis and neuronal hyperexcitability and group I mGluRs play important pathogenetic roles in transgenic AD-model animals. Moreover, the specific binding of Aβs to the CaSRs of human cortical astrocytes and neurons cultured in vitro engenders a pathological signaling that crucially promotes the surplus synthesis and release of Aβs and hyperphosphorylated Tau proteins, and also of nitric oxide, vascular endothelial growth factor-A, and proinflammatory agents. Concurrently, Aβs•CaSR signaling hinders the release of soluble (s)APP-α peptide, a neurotrophic agent and GABABR1a agonist. Altogether these effects progressively kill human cortical neurons in vitro and likely also in vivo. Several CaSR’s negative allosteric modulators suppress all the noxious effects elicited by Aβs•CaSR signaling in human cortical astrocytes and neurons thus safeguarding neurons’ viability in vitro and raising hopes about their potential therapeutic benefits in AD patients. Further basic and clinical investigations on these hot topics are needed taking always heed that activation of the several brain family C GPCRs may elicit divergent upshots according to the models studied.
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Affiliation(s)
- Ilaria Dal Prà
- Human Histology and Embryology Unit, University of Verona Medical School, Verona, Italy
| | - Ubaldo Armato
- Human Histology and Embryology Unit, University of Verona Medical School, Verona, Italy
| | - Anna Chiarini
- Human Histology and Embryology Unit, University of Verona Medical School, Verona, Italy
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16
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The Nervous System Relevance of the Calcium Sensing Receptor in Health and Disease. Molecules 2019; 24:molecules24142546. [PMID: 31336912 PMCID: PMC6680999 DOI: 10.3390/molecules24142546] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Revised: 07/05/2019] [Accepted: 07/10/2019] [Indexed: 02/08/2023] Open
Abstract
The calcium sensing receptor (CaSR) was first identified in parathyroid glands, and its primary role in controlling systemic calcium homeostasis by the regulation of parathyroid hormone (PTH) secretion has been extensively described in literature. Additionally, the receptor has also been investigated in cells and tissues not directly involved in calcium homeostasis, e.g., the nervous system (NS), where it plays crucial roles in early neural development for the differentiation of neurons and glial cells, as well as in the adult nervous system for synaptic transmission and plasticity. Advances in the knowledge of the CaSR's function in such physiological processes have encouraged researchers to further broaden the receptor's investigation in the neuro-pathological conditions of the NS. Interestingly, pre-clinical data suggest that receptor inhibition by calcilytics might be effective in counteracting the pathomechanism underlying Alzheimer's disease and ischemia, while a CaSR positive modulation with calcimimetics has been proposed as a potential approach for treating neuroblastoma. Importantly, such promising findings led to the repurposing of CaSR modulators as novel pharmacological alternatives for these disorders. Therefore, the aim of this review article is to critically appraise evidence which, so far, has been yielded from the investigation of the role of the CaSR in physiology of the nervous system and to focus on the most recent emerging concepts which have reported the receptor as a therapeutic target for neurodegeneration and neuroblastic tumors.
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17
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Hannan FM, Kallay E, Chang W, Brandi ML, Thakker RV. The calcium-sensing receptor in physiology and in calcitropic and noncalcitropic diseases. Nat Rev Endocrinol 2018; 15:33-51. [PMID: 30443043 PMCID: PMC6535143 DOI: 10.1038/s41574-018-0115-0] [Citation(s) in RCA: 191] [Impact Index Per Article: 31.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The Ca2+-sensing receptor (CaSR) is a dimeric family C G protein-coupled receptor that is expressed in calcitropic tissues such as the parathyroid glands and the kidneys and signals via G proteins and β-arrestin. The CaSR has a pivotal role in bone and mineral metabolism, as it regulates parathyroid hormone secretion, urinary Ca2+ excretion, skeletal development and lactation. The importance of the CaSR for these calcitropic processes is highlighted by loss-of-function and gain-of-function CaSR mutations that cause familial hypocalciuric hypercalcaemia and autosomal dominant hypocalcaemia, respectively, and also by the fact that alterations in parathyroid CaSR expression contribute to the pathogenesis of primary and secondary hyperparathyroidism. Moreover, the CaSR is an established therapeutic target for hyperparathyroid disorders. The CaSR is also expressed in organs not involved in Ca2+ homeostasis: it has noncalcitropic roles in lung and neuronal development, vascular tone, gastrointestinal nutrient sensing, wound healing and secretion of insulin and enteroendocrine hormones. Furthermore, the abnormal expression or function of the CaSR is implicated in cardiovascular and neurological diseases, as well as in asthma, and the CaSR is reported to protect against colorectal cancer and neuroblastoma but increase the malignant potential of prostate and breast cancers.
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Affiliation(s)
- Fadil M Hannan
- Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, UK
- Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Enikö Kallay
- Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria
| | - Wenhan Chang
- Endocrine Research Unit, Veterans Affairs Medical Center, University of California, San Francisco, San Francisco, CA, USA
| | - Maria Luisa Brandi
- Metabolic Bone Diseases Unit, Department of Surgery and Translational Medicine, University of Florence, Florence, Italy.
| | - Rajesh V Thakker
- Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford, UK.
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18
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Gorvin CM. Insights into calcium-sensing receptor trafficking and biased signalling by studies of calcium homeostasis. J Mol Endocrinol 2018; 61:R1-R12. [PMID: 29599414 DOI: 10.1530/jme-18-0049] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 03/29/2018] [Indexed: 12/18/2022]
Abstract
The calcium-sensing receptor (CASR) is a class C G-protein-coupled receptor (GPCR) that detects extracellular calcium concentrations, and modulates parathyroid hormone secretion and urinary calcium excretion to maintain calcium homeostasis. The CASR utilises multiple heterotrimeric G-proteins to mediate signalling effects including activation of intracellular calcium release; mitogen-activated protein kinase (MAPK) pathways; membrane ruffling; and inhibition of cAMP production. By studying germline mutations in the CASR and proteins within its signalling pathway that cause hyper- and hypocalcaemic disorders, novel mechanisms governing GPCR signalling and trafficking have been elucidated. This review focusses on two recently described pathways that provide novel insights into CASR signalling and trafficking mechanisms. The first, identified by studying a CASR gain-of-function mutation that causes autosomal dominant hypocalcaemia (ADH), demonstrated a structural motif located between the third transmembrane domain and the second extracellular loop of the CASR that mediates biased signalling by activating a novel β-arrestin-mediated G-protein-independent pathway. The second, in which the mechanism by which adaptor protein-2 σ-subunit (AP2σ) mutations cause familial hypocalciuric hypercalcaemia (FHH) was investigated, demonstrated that AP2σ mutations impair CASR internalisation and reduce multiple CASR-mediated signalling pathways. Furthermore, these studies showed that the CASR can signal from the cell surface using multiple G-protein pathways, whilst sustained signalling is mediated only by the Gq/11 pathway. Thus, studies of FHH- and ADH-associated mutations have revealed novel steps by which CASR mediates signalling and compartmental bias, and these pathways could provide new targets for therapies for patients with calcaemic disorders.
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Affiliation(s)
- Caroline M Gorvin
- Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Birmingham, UK
- Centre for Endocrinology, Diabetes and Metabolism (CEDAM), Birmingham Health Partners, Birmingham, UK
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19
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Jain RA, Wolman MA, Marsden KC, Nelson JC, Shoenhard H, Echeverry FA, Szi C, Bell H, Skinner J, Cobbs EN, Sawada K, Zamora AD, Pereda AE, Granato M. A Forward Genetic Screen in Zebrafish Identifies the G-Protein-Coupled Receptor CaSR as a Modulator of Sensorimotor Decision Making. Curr Biol 2018; 28:1357-1369.e5. [PMID: 29681477 DOI: 10.1016/j.cub.2018.03.025] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Revised: 01/24/2018] [Accepted: 03/13/2018] [Indexed: 12/26/2022]
Abstract
Animals continuously integrate sensory information and select contextually appropriate responses. Here, we show that zebrafish larvae select a behavioral response to acoustic stimuli from a pre-existing choice repertoire in a context-dependent manner. We demonstrate that this sensorimotor choice is modulated by stimulus quality and history, as well as by neuromodulatory systems-all hallmarks of more complex decision making. Moreover, from a genetic screen coupled with whole-genome sequencing, we identified eight mutants with deficits in this sensorimotor choice, including mutants of the vertebrate-specific G-protein-coupled extracellular calcium-sensing receptor (CaSR), whose function in the nervous system is not well understood. We demonstrate that CaSR promotes sensorimotor decision making acutely through Gαi/o and Gαq/11 signaling, modulated by clathrin-mediated endocytosis. Combined, our results identify the first set of genes critical for behavioral choice modulation in a vertebrate and reveal an unexpected critical role for CaSR in sensorimotor decision making.
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Affiliation(s)
- Roshan A Jain
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Biology, Haverford College, Haverford, PA 19041, USA.
| | - Marc A Wolman
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Kurt C Marsden
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jessica C Nelson
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Hannah Shoenhard
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Fabio A Echeverry
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Rose F. Kennedy Center, 1410 Pelham Parkway South, Bronx, NY 10461, USA
| | - Christina Szi
- Department of Biology, Haverford College, Haverford, PA 19041, USA
| | - Hannah Bell
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Julianne Skinner
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Emilia N Cobbs
- Department of Biology, Haverford College, Haverford, PA 19041, USA
| | - Keisuke Sawada
- Department of Biology, Haverford College, Haverford, PA 19041, USA
| | - Amy D Zamora
- Department of Biology, Haverford College, Haverford, PA 19041, USA
| | - Alberto E Pereda
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Rose F. Kennedy Center, 1410 Pelham Parkway South, Bronx, NY 10461, USA
| | - Michael Granato
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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20
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Gerbino A, Colella M. The Different Facets of Extracellular Calcium Sensors: Old and New Concepts in Calcium-Sensing Receptor Signalling and Pharmacology. Int J Mol Sci 2018; 19:E999. [PMID: 29584660 PMCID: PMC5979557 DOI: 10.3390/ijms19040999] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 03/23/2018] [Accepted: 03/25/2018] [Indexed: 12/14/2022] Open
Abstract
The current interest of the scientific community for research in the field of calcium sensing in general and on the calcium-sensing Receptor (CaR) in particular is demonstrated by the still increasing number of papers published on this topic. The extracellular calcium-sensing receptor is the best-known G-protein-coupled receptor (GPCR) able to sense external Ca2+ changes. Widely recognized as a fundamental player in systemic Ca2+ homeostasis, the CaR is ubiquitously expressed in the human body where it activates multiple signalling pathways. In this review, old and new notions regarding the mechanisms by which extracellular Ca2+ microdomains are created and the tools available to measure them are analyzed. After a survey of the main signalling pathways triggered by the CaR, a special attention is reserved for the emerging concepts regarding CaR function in the heart, CaR trafficking and pharmacology. Finally, an overview on other Ca2+ sensors is provided.
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Affiliation(s)
- Andrea Gerbino
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari, 70121 Bari, Italy.
| | - Matilde Colella
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari, 70121 Bari, Italy.
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21
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Gardenal E, Chiarini A, Armato U, Dal Prà I, Verkhratsky A, Rodríguez JJ. Increased Calcium-Sensing Receptor Immunoreactivity in the Hippocampus of a Triple Transgenic Mouse Model of Alzheimer's Disease. Front Neurosci 2017; 11:81. [PMID: 28261055 PMCID: PMC5312420 DOI: 10.3389/fnins.2017.00081] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 02/03/2017] [Indexed: 01/02/2023] Open
Abstract
The Calcium-Sensing Receptor (CaSR) is a G-protein coupled, 7-transmembrane domain receptor ubiquitously expressed throughout the body, brain including. The role of CaSR in the CNS is not well understood; its expression is increasing during development, which has been implicated in memory formation and consolidation, and CaSR localization in nerve terminals has been related to synaptic plasticity and neurotransmission. There is an emerging evidence of CaSR involvement in neurodegenerative disorders and Alzheimer's disease (AD) in particular, where the over-production of β-amyloid peptides was reported to activate CaSR. In the present study, we performed CaSR immunohistochemical and densitometry analysis in the triple transgenic mouse model of AD (3xTg-AD). We found an increase in the expression of CaSR in hippocampal CA1 area and in dentate gyrus in the 3xTg-AD mice when compared to non-transgenic control animals. This increase was significant at 9 months of age and further increased at 12 and 18 months of age. This increase paralleled the accumulation of β-amyloid plaques with age. Increased expression of CaSR favors β-amyloidogenic pathway following direct interactions between β-amyloid and CaSR and hence may contribute to the pathological evolution of the AD. In the framework of this paradigm CaSR may represent a novel therapeutic target.
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Affiliation(s)
- Emanuela Gardenal
- Human Histology and Embryology Unit, Medical School, University of VeronaVerona, Italy; Basque Foundation for Science, Achúcarro Basque Center for Neuroscience, IKERBASQUEBilbao, Spain; Department of Neuroscience, University of the Basque Country (UPV/EHU)Leioa, Spain
| | - Anna Chiarini
- Human Histology and Embryology Unit, Medical School, University of Verona Verona, Italy
| | - Ubaldo Armato
- Human Histology and Embryology Unit, Medical School, University of Verona Verona, Italy
| | - Ilaria Dal Prà
- Human Histology and Embryology Unit, Medical School, University of Verona Verona, Italy
| | - Alexei Verkhratsky
- Basque Foundation for Science, Achúcarro Basque Center for Neuroscience, IKERBASQUEBilbao, Spain; Department of Neuroscience, University of the Basque Country (UPV/EHU)Leioa, Spain; Faculty of Biology, Medicine and Health, The University of ManchesterManchester, UK
| | - José J Rodríguez
- Basque Foundation for Science, Achúcarro Basque Center for Neuroscience, IKERBASQUEBilbao, Spain; Department of Neuroscience, University of the Basque Country (UPV/EHU)Leioa, Spain
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22
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Leach K, Gregory KJ. Molecular insights into allosteric modulation of Class C G protein-coupled receptors. Pharmacol Res 2017; 116:105-118. [DOI: 10.1016/j.phrs.2016.12.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Revised: 11/18/2016] [Accepted: 12/07/2016] [Indexed: 12/23/2022]
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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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Kim W, Wysolmerski JJ. Calcium-Sensing Receptor in Breast Physiology and Cancer. Front Physiol 2016; 7:440. [PMID: 27746743 PMCID: PMC5043011 DOI: 10.3389/fphys.2016.00440] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 09/16/2016] [Indexed: 12/31/2022] Open
Abstract
The calcium-sensing receptor (CaSR) is expressed in normal breast epithelial cells and in breast cancer cells. During lactation, activation of the CaSR in mammary epithelial cells increases calcium transport into milk and inhibits parathyroid hormone-related protein (PTHrP) secretion into milk and into the circulation. The ability to sense changes in extracellular calcium allows the lactating breast to actively participate in the regulation of systemic calcium and bone metabolism, and to coordinate calcium usage with calcium availability during milk production. Interestingly, as compared to normal breast cells, in breast cancer cells, the regulation of PTHrP secretion by the CaSR becomes rewired due to a switch in its G-protein usage such that activation of the CaSR increases instead of decreases PTHrP production. In normal cells the CaSR couples to Gαi to inhibit cAMP and PTHrP production, whereas in breast cancer cells, it couples to Gαs to stimulate cAMP and PTHrP production. Activation of the CaSR on breast cancer cells regulates breast cancer cell proliferation, death and migration, in part, by stimulating PTHrP production. In this article, we discuss the biology of the CaSR in the normal breast and in breast cancer, and review recent findings suggesting that the CaSR activates a nuclear pathway of PTHrP action that stimulates cellular proliferation and inhibits cell death, helping cancer cells adapt to elevated extracellular calcium levels. Understanding the diverse actions mediated by the CaSR may help us better understand lactation physiology, breast cancer progression and osteolytic bone metastases.
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Affiliation(s)
- Wonnam Kim
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale University School of Medicine New Haven, CT, USA
| | - John J Wysolmerski
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale University School of Medicine New Haven, CT, USA
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Hong AR, Kim YA, Bae JH, Min HS, Kim JH, Shin CS, Kim SY, Kim SW. A Possible Link Between Parathyroid Hormone Secretion and Local Regulation of GABA in Human Parathyroid Adenomas. J Clin Endocrinol Metab 2016; 101:2594-601. [PMID: 27070188 DOI: 10.1210/jc.2015-4329] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
CONTEXT γ-Aminobutyric acid-B receptor 1 (GABABR1) forms a heterodimeric complex with calcium-sensing receptor (CaSR) in human brain tissue. However, the expression and implication of GABABR1 in human parathyroid adenoma has not yet been examined. OBJECTIVE The objective of the study was to examine a possible link between GABABR1 and PTH secretion in human parathyroid adenoma Design and Methods: Sixty-five patients who underwent parathyroidectomy for primary hyperparathyroidism (PHPT) and 29 control patients with normal parathyroid glands were retrospectively included. All patients diagnosed with PHPT had parathyroid adenomas. We evaluated the protein expression of GABABR1, glutamic acid decarboxylase 65/67 (GAD65/67), and various factors proposed as regulators of PTH secretion including CaSR, vitamin D receptor (VDR), CYP24A1, CYP27B1, fibroblast growth factor, and α-klotho in parathyroid tissues from patients with parathyroid adenomas using immunohistochemistry. RESULTS Expressions of CaSR, GABABR1, and VDR were significantly lower in PHPT patients than in control subjects (P < .001 for CaSR and GABABR1; P = .006 for VDR). Protein expression of GAD65/67, which indicates local production and regulation of GABAergic pathway, was significantly increased in PHPT (P < .001). There were no significant differences in CYP24A1, CYP27B1, fibroblast growth factor, and α-klotho expression between the two groups. Expression of GAD65/67 was significantly correlated with VDR, CYP24A1, CYP27B1, and α-klotho in PHPT (all P < .01) but not in the control groups. CaSR expression was positively associated with serum phosphorus level (r = 0.274, P = .029) and GAD65/67 was negatively correlated with serum PTH level (r = -0.342, P = .005). CONCLUSIONS Local production and action of GABA may be regulated in human parathyroid adenomas. This suggests a possible link between PTH secretion and local regulation of GABA in parathyroid adenomas.
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Affiliation(s)
- A Ram Hong
- Departments of Internal Medicine (A.R.H., J.H.B., J.H.K., C.S.S., S.Y.K., S.W.K.) and Pathology (Y.A.K., H.S.M.), Seoul National University College of Medicine, and Departments of Pathology (Y.A.K.) and Internal Medicine (S.W.K.), Seoul Metropolitan Government Boramae Medical Center, Seoul 156-707, Republic of Korea
| | - Young A Kim
- Departments of Internal Medicine (A.R.H., J.H.B., J.H.K., C.S.S., S.Y.K., S.W.K.) and Pathology (Y.A.K., H.S.M.), Seoul National University College of Medicine, and Departments of Pathology (Y.A.K.) and Internal Medicine (S.W.K.), Seoul Metropolitan Government Boramae Medical Center, Seoul 156-707, Republic of Korea
| | - Jae Hyun Bae
- Departments of Internal Medicine (A.R.H., J.H.B., J.H.K., C.S.S., S.Y.K., S.W.K.) and Pathology (Y.A.K., H.S.M.), Seoul National University College of Medicine, and Departments of Pathology (Y.A.K.) and Internal Medicine (S.W.K.), Seoul Metropolitan Government Boramae Medical Center, Seoul 156-707, Republic of Korea
| | - Hye Sook Min
- Departments of Internal Medicine (A.R.H., J.H.B., J.H.K., C.S.S., S.Y.K., S.W.K.) and Pathology (Y.A.K., H.S.M.), Seoul National University College of Medicine, and Departments of Pathology (Y.A.K.) and Internal Medicine (S.W.K.), Seoul Metropolitan Government Boramae Medical Center, Seoul 156-707, Republic of Korea
| | - Jung Hee Kim
- Departments of Internal Medicine (A.R.H., J.H.B., J.H.K., C.S.S., S.Y.K., S.W.K.) and Pathology (Y.A.K., H.S.M.), Seoul National University College of Medicine, and Departments of Pathology (Y.A.K.) and Internal Medicine (S.W.K.), Seoul Metropolitan Government Boramae Medical Center, Seoul 156-707, Republic of Korea
| | - Chan Soo Shin
- Departments of Internal Medicine (A.R.H., J.H.B., J.H.K., C.S.S., S.Y.K., S.W.K.) and Pathology (Y.A.K., H.S.M.), Seoul National University College of Medicine, and Departments of Pathology (Y.A.K.) and Internal Medicine (S.W.K.), Seoul Metropolitan Government Boramae Medical Center, Seoul 156-707, Republic of Korea
| | - Seong Yeon Kim
- Departments of Internal Medicine (A.R.H., J.H.B., J.H.K., C.S.S., S.Y.K., S.W.K.) and Pathology (Y.A.K., H.S.M.), Seoul National University College of Medicine, and Departments of Pathology (Y.A.K.) and Internal Medicine (S.W.K.), Seoul Metropolitan Government Boramae Medical Center, Seoul 156-707, Republic of Korea
| | - Sang Wan Kim
- Departments of Internal Medicine (A.R.H., J.H.B., J.H.K., C.S.S., S.Y.K., S.W.K.) and Pathology (Y.A.K., H.S.M.), Seoul National University College of Medicine, and Departments of Pathology (Y.A.K.) and Internal Medicine (S.W.K.), Seoul Metropolitan Government Boramae Medical Center, Seoul 156-707, Republic of Korea
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Santa Maria C, Cheng Z, Li A, Wang J, Shoback D, Tu CL, Chang W. Interplay between CaSR and PTH1R signaling in skeletal development and osteoanabolism. Semin Cell Dev Biol 2016; 49:11-23. [PMID: 26688334 PMCID: PMC4761456 DOI: 10.1016/j.semcdb.2015.12.004] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Accepted: 12/05/2015] [Indexed: 12/01/2022]
Abstract
Parathyroid hormone (PTH)-related peptide (PTHrP) controls the pace of pre- and post-natal growth plate development by activating the PTH1R in chondrocytes, while PTH maintains mineral and skeletal homeostasis by modulating calciotropic activities in kidneys, gut, and bone. The extracellular calcium-sensing receptor (CaSR) is a member of family C, G protein-coupled receptor, which regulates mineral and skeletal homeostasis by controlling PTH secretion in parathyroid glands and Ca(2+) excretion in kidneys. Recent studies showed the expression of CaSR in chondrocytes, osteoblasts, and osteoclasts and confirmed its non-redundant roles in modulating the recruitment, proliferation, survival, and differentiation of the cells. This review emphasizes the actions of CaSR and PTH1R signaling responses in cartilage and bone and discusses how these two signaling cascades interact to control growth plate development and maintain skeletal metabolism in physiological and pathological conditions. Lastly, novel therapeutic regimens that exploit interrelationship between the CaSR and PTH1R are proposed to produce more robust osteoanabolism.
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Affiliation(s)
- Christian Santa Maria
- Endocrine Research Unit, University of California, San Francisco, Veterans Affairs Medical Center, San Francisco, CA, USA
| | - Zhiqiang Cheng
- Endocrine Research Unit, University of California, San Francisco, Veterans Affairs Medical Center, San Francisco, CA, USA
| | - Alfred Li
- Endocrine Research Unit, University of California, San Francisco, Veterans Affairs Medical Center, San Francisco, CA, USA
| | - Jiali Wang
- Endocrine Research Unit, University of California, San Francisco, Veterans Affairs Medical Center, San Francisco, CA, USA
| | - Dolores Shoback
- Endocrine Research Unit, University of California, San Francisco, Veterans Affairs Medical Center, San Francisco, CA, USA
| | - Chia-Ling Tu
- Endocrine Research Unit, University of California, San Francisco, Veterans Affairs Medical Center, San Francisco, CA, USA
| | - Wenhan Chang
- Endocrine Research Unit, University of California, San Francisco, Veterans Affairs Medical Center, San Francisco, CA, USA.
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Abstract
In addition to its prominent role in the parathyroid gland, the calcium-sensing receptor (CaSR) is expressed in various tissues, including the kidney. This article reviews current data on the calcium-sensing properties of the kidney, the localization of the CaSR protein along the nephron, and its function in calcium homeostasis and in hypercalciuria.
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Affiliation(s)
- Hakan R. Toka
- Division of Nephrology and Hypertension, Eastern Virginia Medical School, Norfolk, Virginia
- Division of Nephrology, Beth Israel Deaconess Medical Center, Boston, Massachussetts; and
| | - Martin R. Pollak
- Division of Nephrology, Beth Israel Deaconess Medical Center, Boston, Massachussetts; and
| | - Pascal Houillier
- Université Paris-Descartes, Sorbonne Paris-Cité, Centre de Recherche des Cordeliers, INSERM UMRS 1138, Service de Physiologie, Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Paris, France
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28
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Zhang C, Miller CL, Brown EM, Yang JJ. The calcium sensing receptor: from calcium sensing to signaling. SCIENCE CHINA-LIFE SCIENCES 2015; 58:14-27. [DOI: 10.1007/s11427-014-4779-y] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2014] [Accepted: 10/21/2014] [Indexed: 12/14/2022]
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Kim JY, Ho H, Kim N, Liu J, Tu CL, Yenari MA, Chang W. Calcium-sensing receptor (CaSR) as a novel target for ischemic neuroprotection. Ann Clin Transl Neurol 2014; 1:851-66. [PMID: 25540800 PMCID: PMC4265057 DOI: 10.1002/acn3.118] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 08/14/2014] [Accepted: 08/15/2014] [Indexed: 01/04/2023] Open
Abstract
Object Ischemic brain injury is the leading cause for death and long-term disability in patients who suffer cardiac arrest and embolic stroke. Excitotoxicity and subsequent Ca2+-overload lead to ischemic neuron death. We explore a novel mechanism concerning the role of the excitatory extracellular calcium-sensing receptor (CaSR) in the induction of ischemic brain injury. Method Mice were exposed to forebrain ischemia and the actions of CaSR were determined after its genes were ablated specifically in hippocampal neurons or its activities were inhibited pharmacologically. Since the CaSR forms a heteromeric complex with the inhibitory type B γ-aminobutyric acid receptor 1 (GABABR1), we compared neuronal responses to ischemia in mice deficient in CaSR, GABABR1, or both, and in mice injected locally or systemically with a specific CaSR antagonist (or calcilytic) in the presence or absence of a GABABR1 agonist (baclofen). Results Both global and focal brain ischemia led to CaSR overexpression and GABABR1 downregulation in injured neurons. Genetic ablation of Casr genes or blocking CaSR activities by calcilytics rendered robust neuroprotection and preserved learning and memory functions in ischemic mice, partly by restoring GABABR1 expression. Concurrent ablation of Gabbr1 gene blocked the neuroprotection caused by the Casr gene knockout. Coinjection of calcilytics with baclofen synergistically enhanced neuroprotection. This combined therapy remained robust when given 6 h after ischemia. Interpretation Our study demonstrates a novel receptor interaction, which contributes to ischemic neuron death through CaSR upregulation and GABABR1 downregulation, and feasibility of neuroprotection by concurrently targeting these two receptors.
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Affiliation(s)
- Jong Youl Kim
- Endocrine Unit, University of California San Francisco and Veterans Affairs Medical Center San Francisco, California, 94121 ; Department of Neurology, University of California San Francisco and Veterans Affairs Medical Center San Francisco, California, 94121
| | - Hanson Ho
- Endocrine Unit, University of California San Francisco and Veterans Affairs Medical Center San Francisco, California, 94121
| | - Nuri Kim
- Department of Neurology, University of California San Francisco and Veterans Affairs Medical Center San Francisco, California, 94121
| | - Jialing Liu
- Neurological Surgery, University of California San Francisco and Veterans Affairs Medical Center San Francisco, California, 94121
| | - Chia-Ling Tu
- Endocrine Unit, University of California San Francisco and Veterans Affairs Medical Center San Francisco, California, 94121
| | - Midori A Yenari
- Department of Neurology, University of California San Francisco and Veterans Affairs Medical Center San Francisco, California, 94121
| | - Wenhan Chang
- Endocrine Unit, University of California San Francisco and Veterans Affairs Medical Center San Francisco, California, 94121
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Tao YX, Conn PM. Chaperoning G protein-coupled receptors: from cell biology to therapeutics. Endocr Rev 2014; 35:602-47. [PMID: 24661201 PMCID: PMC4105357 DOI: 10.1210/er.2013-1121] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Accepted: 03/14/2014] [Indexed: 12/13/2022]
Abstract
G protein-coupled receptors (GPCRs) are membrane proteins that traverse the plasma membrane seven times (hence, are also called 7TM receptors). The polytopic structure of GPCRs makes the folding of GPCRs difficult and complex. Indeed, many wild-type GPCRs are not folded optimally, and defects in folding are the most common cause of genetic diseases due to GPCR mutations. Both general and receptor-specific molecular chaperones aid the folding of GPCRs. Chemical chaperones have been shown to be able to correct the misfolding in mutant GPCRs, proving to be important tools for studying the structure-function relationship of GPCRs. However, their potential therapeutic value is very limited. Pharmacological chaperones (pharmacoperones) are potentially important novel therapeutics for treating genetic diseases caused by mutations in GPCR genes that resulted in misfolded mutant proteins. Pharmacoperones also increase cell surface expression of wild-type GPCRs; therefore, they could be used to treat diseases that do not harbor mutations in GPCRs. Recent studies have shown that indeed pharmacoperones work in both experimental animals and patients. High-throughput assays have been developed to identify new pharmacoperones that could be used as therapeutics for a number of endocrine and other genetic diseases.
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Affiliation(s)
- Ya-Xiong Tao
- Department of Anatomy, Physiology, and Pharmacology (Y.-X.T.), College of Veterinary Medicine, Auburn University, Auburn, Alabama 36849-5519; and Departments of Internal Medicine and Cell Biology (P.M.C.), Texas Tech University Health Science Center, Lubbock, Texas 79430-6252
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Sorting nexin 27 regulation of G protein-gated inwardly rectifying K⁺ channels attenuates in vivo cocaine response. Neuron 2014; 82:659-69. [PMID: 24811384 DOI: 10.1016/j.neuron.2014.03.011] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/26/2014] [Indexed: 12/12/2022]
Abstract
The subcellular pathways that regulate G protein-gated inwardly rectifying potassium (GIRK or Kir3) channels are important for controlling the excitability of neurons. Sorting nexin 27 (SNX27) is a PDZ-containing protein known to bind GIRK2c/GIRK3 channels, but its function in vivo is poorly understood. Here, we investigated the role of SNX27 in regulating GIRK currents in dopamine (DA) neurons of the ventral tegmental area (VTA). Mice lacking SNX27 in DA neurons exhibited reduced GABABR-activated GIRK currents but had normal Ih currents and DA D2R-activated GIRK currents. Expression of GIRK2a, an SNX27-insensitive splice variant, restored GABABR-activated GIRK currents in SNX27-deficient DA neurons. Remarkably, mice with significantly reduced GABABR-activated GIRK currents in only DA neurons were hypersensitive to cocaine and could be restored to a normal locomotor response with GIRK2a expression. These results identify a pathway for regulating excitability of VTA DA neurons, highlighting SNX27 as a promising target for treating addiction.
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Fève M, Saliou JM, Zeniou M, Lennon S, Carapito C, Dong J, Van Dorsselaer A, Junier MP, Chneiweiss H, Cianférani S, Haiech J, Kilhoffer MC. Comparative expression study of the endo-G protein coupled receptor (GPCR) repertoire in human glioblastoma cancer stem-like cells, U87-MG cells and non malignant cells of neural origin unveils new potential therapeutic targets. PLoS One 2014; 9:e91519. [PMID: 24662753 PMCID: PMC3963860 DOI: 10.1371/journal.pone.0091519] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2013] [Accepted: 02/10/2014] [Indexed: 12/22/2022] Open
Abstract
Glioblastomas (GBMs) are highly aggressive, invasive brain tumors with bad prognosis and unmet medical need. These tumors are heterogeneous being constituted by a variety of cells in different states of differentiation. Among these, cells endowed with stem properties, tumor initiating/propagating properties and particularly resistant to chemo- and radiotherapies are designed as the real culprits for tumor maintenance and relapse after treatment. These cells, termed cancer stem-like cells, have been designed as prominent targets for new and more efficient cancer therapies. G-protein coupled receptors (GPCRs), a family of membrane receptors, play a prominent role in cell signaling, cell communication and crosstalk with the microenvironment. Their role in cancer has been highlighted but remains largely unexplored. Here, we report a descriptive study of the differential expression of the endo-GPCR repertoire in human glioblastoma cancer stem-like cells (GSCs), U-87 MG cells, human astrocytes and fetal neural stem cells (f-NSCs). The endo-GPCR transcriptome has been studied using Taqman Low Density Arrays. Of the 356 GPCRs investigated, 138 were retained for comparative studies between the different cell types. At the transcriptomic level, eight GPCRs were specifically expressed/overexpressed in GSCs. Seventeen GPCRs appeared specifically expressed in cells with stem properties (GSCs and f-NSCs). Results of GPCR expression at the protein level using mass spectrometry and proteomic analysis are also presented. The comparative GPCR expression study presented here gives clues for new pathways specifically used by GSCs and unveils novel potential therapeutic targets.
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Affiliation(s)
- Marie Fève
- Laboratoire d'Innovation Thérapeutique, UMR7200, Laboratoire d'Excellence Medalis, CNRS, Université de Strasbourg, Faculté de Pharmacie, Illkirch, France
| | - Jean-Michel Saliou
- Laboratoire de Spectrométrie de Masse BioOrganique, UMR7178, CNRS, Institut Pluridisciplinaire Hubert Curien, Université de Strasbourg, Strasbourg, France
| | - Maria Zeniou
- Laboratoire d'Innovation Thérapeutique, UMR7200, Laboratoire d'Excellence Medalis, CNRS, Université de Strasbourg, Faculté de Pharmacie, Illkirch, France
| | - Sarah Lennon
- Laboratoire de Spectrométrie de Masse BioOrganique, UMR7178, CNRS, Institut Pluridisciplinaire Hubert Curien, Université de Strasbourg, Strasbourg, France
| | - Christine Carapito
- Laboratoire de Spectrométrie de Masse BioOrganique, UMR7178, CNRS, Institut Pluridisciplinaire Hubert Curien, Université de Strasbourg, Strasbourg, France
| | - Jihu Dong
- Laboratoire d'Innovation Thérapeutique, UMR7200, Laboratoire d'Excellence Medalis, CNRS, Université de Strasbourg, Faculté de Pharmacie, Illkirch, France
| | - Alain Van Dorsselaer
- Laboratoire de Spectrométrie de Masse BioOrganique, UMR7178, CNRS, Institut Pluridisciplinaire Hubert Curien, Université de Strasbourg, Strasbourg, France
| | - Marie-Pierre Junier
- Neuroscience Paris Seine, UMR8246, Inserm U1130, Institut de Biologie Paris Seine, CNRS, Université Pierre et Marie Curie, Paris, France
| | - Hervé Chneiweiss
- Neuroscience Paris Seine, UMR8246, Inserm U1130, Institut de Biologie Paris Seine, CNRS, Université Pierre et Marie Curie, Paris, France
| | - Sarah Cianférani
- Laboratoire de Spectrométrie de Masse BioOrganique, UMR7178, CNRS, Institut Pluridisciplinaire Hubert Curien, Université de Strasbourg, Strasbourg, France
| | - Jacques Haiech
- Laboratoire d'Innovation Thérapeutique, UMR7200, Laboratoire d'Excellence Medalis, CNRS, Université de Strasbourg, Faculté de Pharmacie, Illkirch, France
| | - Marie-Claude Kilhoffer
- Laboratoire d'Innovation Thérapeutique, UMR7200, Laboratoire d'Excellence Medalis, CNRS, Université de Strasbourg, Faculté de Pharmacie, Illkirch, France
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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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Mild Hypothermia Suppresses Calcium-Sensing Receptor (CaSR) Induction Following Forebrain Ischemia While Increasing GABA-B Receptor 1 (GABA-B-R1) Expression. Transl Stroke Res 2013; 2:195-201. [PMID: 21731589 DOI: 10.1007/s12975-011-0082-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Hypothermia improves neurological outcome from cardiac arrest. The mechanisms of protection are multifold, but identifying some may be useful in exploring potential therapeutic targets. The extracellular calcium-sensing receptor (CaSR) was originally found in parathyroid cells in which the receptor senses minute changes in extracellular [Ca(2+)] and promotes Ca(2+) influx and intracellular Ca(2+) release. The CaSR is broadly expressed in the CNS and colocalized with the inhibitory γ-aminobutyric acid-B receptor 1 (GABA-B-R1). In hippocampal neurons, GABA-B-R1 heterodimerizes with CaSR and suppresses CaSR expression. To study the interplay between these two receptors in the development of ischemic cell death and neuroprotection by hypothermia, we subjected C57/BL6 mice to global cerebral ischemia by performing bilateral carotid artery occlusion (10 min) followed by reperfusion for 1-3 days with or without therapeutic hypothermia (33°C for 3 h at the onset of reperfusion). Terminal deoxynucleotidyl transferase dUTP nick end labeling staining and immunohistochemistry showed that forebrain ischemia increased CaSR expression, decreased GABA-B-R1 expression, and promoted cell death. These changes were particularly evident in hippocampal neurons and could be reversed by mild hypothermia. The induction of CaSR, along with reciprocal decreases in GABA-B-R1 expression, may together potentiate ischemic neuronal death, suggesting a new therapeutic target for treatment of ischemic brain injury.
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35
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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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Riccardi D, Brennan SC, Chang W. The extracellular calcium-sensing receptor, CaSR, in fetal development. Best Pract Res Clin Endocrinol Metab 2013; 27:443-53. [PMID: 23856271 PMCID: PMC4462341 DOI: 10.1016/j.beem.2013.02.010] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
In fetal mammals, serum levels of both total and ionized calcium significantly exceed those in the adult. This relative fetal hypercalcemia is crucial for skeletal development and is maintained irrespectively of maternal serum calcium levels. Elegant studies by Kovacs and Kronenberg have previously addressed the role of the CaSR in creating and maintaining this relative fetal hypercalcemia, through the regulation of parathyroid hormone-related peptide secretion. More recently we have shown that the CaSR is widely distributed throughout the developing fetus, where the receptor plays major, unexpected roles in ensuring growth and maturation of several organs. In this article, we present evidence for a role of the CaSR in the control of skeletal development, and how fetal hypercalcemia, acting through the CaSR, regulates lung development.
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Affiliation(s)
- Daniela Riccardi
- School of Biosciences, Cardiff University, Cardiff, United Kingdom
| | - Sarah C Brennan
- School of Biosciences, Cardiff University, Cardiff, United Kingdom
| | - Wenhan Chang
- University of California San Francisco, California, USA
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Abstract
The calcium sensing receptor (CaSR) is expressed by subpopulations of neuronal and glial cells throughout the brain and is activated by extracellular calcium [Formula: see text] . During development, the CaSR regulates neuronal cell growth and migration as well as oligodendroglial maturation and function. Emerging evidence suggests that in nerve terminals, CaSR is implicated in synaptic plasticity and neurotransmission. In this review, we analyze the roles attributed to CaSR in regulating diverse brain functions, including central regulation of body fluid composition and blood pressure. We also discuss the potential relevance of Ca(2+)-sensing in brain by other family C G protein-coupled receptors. Finally, evidence that the CaSR contributes to the pathogenesis of various brain disorders raises the possibility that pharmacological modulators of the CaSR may have therapeutic benefit.
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Affiliation(s)
- Martial Ruat
- CNRS-UPR-3294, Laboratory of Neurobiology and Development, Institute of Neurobiology, Alfred Fessard IFR2118, Signal Transduction and Developmental Neuropharmacology Team, 1 Avenue de la Terrasse, F-91198, Gif-sur-Yvette, France.
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Abstract
Elevated extracellular Ca(2+) concentrations stimulate the G-protein coupled receptor calcium-sensing receptor. Here we show that this stimulation induces the expression of biologically active early growth response protein 1 (Egr-1), a zinc finger transcription factor. Expression of a dominant-negative mutant of the ternary complex factor Ets-like protein-1 (Elk-1), a key transcriptional regulator of serum response element-driven gene transcription, prevented Egr-1 expression, indicating that Elk-1 or related ternary complex factors connect the intracellular signaling cascade elicited by activation of calcium-sensing receptors with transcription of the Egr-1 gene. These data were corroborated by the fact that stimulation of calcium-sensing receptors increased the transcriptional activation potential of Elk-1. In addition, activator protein-1 (AP-1) transcriptional activity was significantly elevated after the stimulation of calcium-sensing receptors. The expression of a dominant-negative mutant of Elk-1 reduced c-Fos expression and prevented the up-regulation of AP-1 activity as a result of calcium-sensing receptor stimulation, indicating that ternary complex factors control both Egr-1- and AP-1-regulated transcription. In addition, AP-1 activity was reduced after the expression of a dominant-negative mutant of c-Jun in cells expressing an activated calcium-sensing receptor. Stimulus-transcription coupling leading to the up-regulation of Egr-1 and AP-1 controlled transcription in cells expressing calcium-sensing receptors required the protein kinases Raf and ERK, whereas the overexpression of MAPK phosphatase-1 interrupted the signaling cascade connecting calcium-sensing receptor stimulation with transcription of Egr-1 and AP-1 controlled genes. The fact that calcium-sensing receptor stimulation activates the transcription factors Egr-1, Elk-1, and AP-1 indicates that regulation of gene transcription is an integral part of calcium-sensing receptor induced signaling.
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Affiliation(s)
- Gerald Thiel
- Department of Medical Biochemistry and Molecular Biology, University of Saarland Medical Center, D-66421 Homburg, Germany.
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Cheng SX. Calcium-sensing receptor inhibits secretagogue-induced electrolyte secretion by intestine via the enteric nervous system. Am J Physiol Gastrointest Liver Physiol 2012; 303:G60-70. [PMID: 22517767 PMCID: PMC3404579 DOI: 10.1152/ajpgi.00425.2011] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Bacterial toxins such as cholera toxin induce diarrhea by both direct epithelial cell generation of cyclic nucleotides as well as stimulation of the enteric nervous system (ENS). Agonists of the extracellular calcium-sensing receptor (CaSR) can reduce toxin-stimulated fluid secretion in ENS-absent colonic epithelial crypts by increasing phosphodiesterase-dependent cyclic-nucleotide degradation. Here we show that the CaSR is also highly expressed in tetrodotoxin (TTX)-sensitive neurons comprising the ENS, suggesting that CaSR agonists might also function through neuronal pathways. To test this hypothesis, rat colon segments containing intact ENS were isolated and mounted on Ussing chambers. Basal and cyclic nucleotide-stimulated electrolyte secretions were monitored by measuring changes in short-circuit current (I(sc)). CaSR was activated by R-568 and its effects were compared in the presence and absence of TTX. Consistent with active regulation of anion secretion by the ENS, a significant proportion of I(sc) in the proximal and distal colon was inhibited by serosal TTX, both at basal and under cyclic AMP-stimulated conditions. In the absence of TTX, activation of CaSR with R-568 significantly reduced basal I(sc) and cyclic AMP-stimulated I(sc); it also completely reversed the cAMP-stimulated secretory responses if the drug was applied after the forskolin stimulation. Such inhibitory effects of R-568 were either absent or significantly reduced when serosal TTX was present, suggesting that this agonist exerts its antisecretory effect on the intestine by inhibiting ENS. The present results suggest a new model for regulating intestinal fluid transport in which neuronal and nonneuronal secretagogue actions are modulated by the inhibitory effects of CaSR on the ENS. The ability of a CaSR agonist to reduce secretagogue-stimulated Cl(-) secretion might provide a new therapeutic approach for secretory and other ENS-mediated diarrheal conditions.
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Affiliation(s)
- Sam X. Cheng
- 1Department of Pediatrics, School of Medicine, Yale University, New Haven, Connecticut; and ,2Department of Pediatrics, School of Medicine, University of Florida, Gainesville, Florida
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Gassmann M, Bettler B. Regulation of neuronal GABA(B) receptor functions by subunit composition. Nat Rev Neurosci 2012; 13:380-94. [PMID: 22595784 DOI: 10.1038/nrn3249] [Citation(s) in RCA: 248] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
GABA(B) receptors (GABA(B)Rs) are G protein-coupled receptors for GABA, the main inhibitory neurotransmitter in the CNS. In the past 5 years, notable advances have been made in our understanding of the molecular composition of these receptors. GABA(B)Rs are now known to comprise principal and auxiliary subunits that influence receptor properties in distinct ways. The principal subunits regulate the surface expression and the axonal versus dendritic distribution of these receptors, whereas the auxiliary subunits determine agonist potency and the kinetics of the receptor response. This Review summarizes current knowledge on how the subunit composition of GABA(B)Rs affects the distribution of these receptors, neuronal processes and higher brain functions.
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Affiliation(s)
- Martin Gassmann
- Department of Biomedicine, Institute of Physiology, University of Basel, Klingelbergstr. 50-70, 4056 Basel, Switzerland.
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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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Boyer SB, Slesinger PA. Probing novel GPCR interactions using a combination of FRET and TIRF. Commun Integr Biol 2011; 3:343-6. [PMID: 20798821 DOI: 10.4161/cib.3.4.11764] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2010] [Accepted: 03/08/2010] [Indexed: 12/23/2022] Open
Abstract
Recent work on G-protein coupled receptors (GPCRs) has highlighted the importance of homo- and heterodimerization in all areas of GPCR function, including trafficking, signaling and desensitization. Novel GPCR dimers and even high-order oligomers are constantly being discovered. Advances in techniques such as fluorescent microscopy have improved our ability to detect these interactions. As GPCRs represent the largest class of transmembrane signaling molecules in biology, these new insights into their function could vastly improve our understanding of the complex physiological role GPCRs play in cellular signaling. Utilizing a combination of classic biochemical approaches and newer techniques such as fluorescence resonance energy transfer (FRET) and total internal reflection fluorescence microscopy (TIRF), we recently demonstrated a novel interaction between M(2) muscarinic receptors and GABA(B) receptors. In this addendum, we address technical aspects of combining FRET and TIRF to study GPCR interactions and further discuss the physiological implications of the M(2)-GABA(B) heterodimer.
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Affiliation(s)
- Stephanie B Boyer
- Peptide Biology Laboratory; The Salk Institute for Biological Studies; La Jolla, CA USA
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Nutrient sensing receptors in gastric endocrine cells. J Mol Histol 2011; 42:355-64. [PMID: 21750971 DOI: 10.1007/s10735-011-9339-1] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Accepted: 07/05/2011] [Indexed: 10/18/2022]
Abstract
Sensing protein breakdown products in the luminal content is of particular importance for the regulation of digestive activities in the stomach which are mainly governed by gastric hormones. The molecular basis for tuning the release of hormones according to the protein content is still elusive. In this study we have analysed the murine stomach for candidate nutrient receptors. As a promising candidate we have concentrated on the broadly tuned amino acid receptor GPRC6A. Expression of GPRC6A could be demonstrated in different regions of the murine stomach; especially in the gastric antrum. Using immunohistochemical approaches, a large cell population of GPRC6A-positive cells was visualized in the basal half of the antral gastric mucosa. Molecular phenotyping of GPRC6A-immunoreactive cells revealed that most of them contained the peptide hormone gastrin. A small population turned out to be immunoreactive for somatostatin. In search for additional amino acid receptors in antral gastric mucosa, we obtained evidence for expression of the gustatory amino acid receptor subunit T1R3 and the calcium-sensing receptor CaSR. Many CaSR-cells were found in the gastric antrum and most of them also contained gastrin; very similar to GPRC6A-cells. In contrast, T1R3 was found only in a small population of gastrin-negative cells. The finding that GPRC6A-and CaSR-receptors are both expressed in many if not all gastrin cells strongly suggests that both receptor types are co-expressed in the same cells, where they could form heterodimers providing a unique response spectrum of these cells.
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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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Kamal M, Jockers R. Biological Significance of GPCR Heteromerization in the Neuro-Endocrine System. Front Endocrinol (Lausanne) 2011; 2:2. [PMID: 22649357 PMCID: PMC3355952 DOI: 10.3389/fendo.2011.00002] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2010] [Accepted: 01/13/2011] [Indexed: 11/26/2022] Open
Abstract
Clustering of proteins in higher order complexes is a common theme in biology and profoundly influences protein function. The idea that seven-transmembrane spanning G protein-coupled receptors (GPCRs) might form dimers or higher order oligomeric complexes has been formulated more than 20 years ago. Since then, this phenomenon has been investigated with many different biochemical and biophysical techniques. The more recent notion of GPCR heteromerization describes the specific association of two different GPCRs. GPCR heteromerization may be of primary importance in neuroendocrinology, as this may explain at least some of the functional crosstalks described between different hormonal systems. Importantly, many GPCR heteromers have distinct functional properties compared to their corresponding homomers. Heteromer-specific pharmacological profiles might be exploited for drug design and open new therapeutic options. GPCR heteromerization has been first studied in heterologous expression systems. Today, increasing evidence for the existence of GPCR heteromers in endogenous systems is emerging providing crucial evidence for the physiological function of GPCR heteromerization.
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Affiliation(s)
- Maud Kamal
- Department of Endocrinology, Metabolism and Cancer, INSERM U1016, Institut CochinParis, France
- CNRS UMR 8104Paris, France
- University Paris DescartesParis, France
| | - Ralf Jockers
- Department of Endocrinology, Metabolism and Cancer, INSERM U1016, Institut CochinParis, France
- CNRS UMR 8104Paris, France
- University Paris DescartesParis, France
- *Correspondence: Ralf Jockers, Institut Cochin, 22 rue Méchain, 75014 Paris, France. e-mail:
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Lee C, Mayfield RD, Harris RA. Intron 4 containing novel GABAB1 isoforms impair GABAB receptor function. PLoS One 2010; 5:e14044. [PMID: 21124972 PMCID: PMC2987798 DOI: 10.1371/journal.pone.0014044] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2010] [Accepted: 10/26/2010] [Indexed: 12/24/2022] Open
Abstract
Background Gamma-aminobutyric acid type B (GABAB) receptors decrease neural activity through G protein signaling. There are two subunits, GABAB1 and GABAB2. Alternative splicing provides GABAB1 with structural and functional diversity. cDNA microarrays showed strong signals from human brain RNA using GABAB1 intron 4 region probes. Therefore, we predicted the existence of novel splice variants. Methodology/Principal Findings Based on the probe sequence analysis, we proposed two possible splice variants, GABAB1j and GABAB1k. The existence of human GABAB1j was verified by quantitative real-time PCR, and mouse GABAB1j was found from a microarray probe set based on human GABAB1j sequence. GABAB1j open reading frames (ORF) and expression patterns are not conserved across species, and they do not have any important functional domains except sushi domains. Thus, we focused on another possible splice variant, GABAB1k. After obtaining PCR evidence for GABAB1k existence from human, mouse, and rat, it was cloned from human and mouse by PCR along with three additional isoforms, GABAB1l, GABAB1m, and GABAB1n. Their expression levels by quantitative real-time PCR are relatively low in brain although they may be expressed in specific cell types. GABAB1l and GABAB1m inhibit GABAB receptor-induced G protein-activated inwardly rectifying K+ channel (GIRK) currents at Xenopus oocyte two-electrode voltage clamp system. Conclusions/Significance This study supports previous suggestions that intron 4 of GABAB1 gene is a frequent splicing spot across species. Like GABAB1e, GABAB1l and GABAB1m do not have transmembrane domains but have a dimerization motif. So, they also could be secreted and bind GABAB2 dominantly instead of GABAB1a. However, only GABAB1l and GABAB1m are N- and C-terminal truncated splicing variants and impair receptor function. This suggests that the intron 4 containing N-terminal truncation is necessary for the inhibitory action of the new splice variants.
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Affiliation(s)
- Changhoon Lee
- Section of Neurobiology and Institute for Cellular and Molecular Biology, Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, Texas, United States of America
- * E-mail:
| | - R. Dayne Mayfield
- Section of Neurobiology and Institute for Cellular and Molecular Biology, Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, Texas, United States of America
| | - R. Adron Harris
- Section of Neurobiology and Institute for Cellular and Molecular Biology, Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, Texas, United States of America
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Padgett CL, Slesinger PA. GABAB receptor coupling to G-proteins and ion channels. ADVANCES IN PHARMACOLOGY 2010; 58:123-47. [PMID: 20655481 DOI: 10.1016/s1054-3589(10)58006-2] [Citation(s) in RCA: 161] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
GABA(B) receptors have been found to play a key role in regulating membrane excitability and synaptic transmission in the brain. The GABA(B) receptor is a G-protein coupled receptor (GPCR) that associates with a subset of G-proteins (pertussis toxin sensitive Gi/o family), that in turn regulate specific ion channels and trigger cAMP cascades. In this review, we describe the relationships between the GABA(B) receptor, its effectors and associated proteins that mediate GABA(B) receptor function within the brain. We discuss a unique feature of the GABA(B) receptor, the requirement for heterodimerization to produce functional receptors, as well as an increasing body of evidence that suggests GABA(B) receptors comprise a macromolecular signaling heterocomplex, critical for efficient targeting and function of the receptors. Within this complex, GABA(B) receptors associate specifically with Gi/o G-proteins that regulate voltage-gated Ca(2+) (Ca(V)) channels, G-protein activated inwardly rectifying K(+) (GIRK) channels, and adenylyl cyclase. Numerous studies have revealed that lipid rafts, scaffold proteins, targeting motifs in the receptor, and regulators of G-protein signaling (RGS) proteins also contribute to the function of GABA(B) receptors and affect cellular processes such as receptor trafficking and activity-dependent desensitization. This complex regulation of GABA(B) receptors in the brain may provide opportunities for new ways to regulate GABA-dependent inhibition in normal and diseased states of the nervous system.
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Affiliation(s)
- Claire L Padgett
- Peptide Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA, USA
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Bandyopadhyay S, Tfelt-Hansen J, Chattopadhyay N. Diverse roles of extracellular calcium-sensing receptor in the central nervous system. J Neurosci Res 2010; 88:2073-82. [PMID: 20336672 DOI: 10.1002/jnr.22391] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The G-protein-coupled calcium-sensing receptor (CaSR), upon activation by Ca(2+) or other physiologically relevant polycationic molecules, performs diverse functions in the brain. The CaSR is widely expressed in the central nervous system (CNS) and is characterized by a robust increase in its expression during postnatal brain development over adult levels throughout the CNS. Developmental increases in CaSR levels in brain correlate with myelinogenesis. Indeed, neural stem cells differentiating to the oligodendrocyte lineage exhibit the highest CaSR expression compared with those differentiating to astrocytic or neuronal lineages. In adult CNS, CaSR has broad relevance in maintaining local ionic homeostasis. CaSR shares an evolutionary relationship with the metabotropic glutamate receptor and forms heteromeric complexes with the type B-aminobutyric acid receptor subunits that affects its cell surface expression, activation, signaling, and functions. In normal physiology as well as in pathologic conditions, CaSR is activated by signals arising from mineral ions, amino acids, polyamines, glutathione, and amyloid-beta in conjunction with Ca(2+) and other divalent cationic ligands. CaSR activation regulates membrane excitability of neurons and glia and affects myelination, olfactory and gustatory signal integration, axonal and dendritic growth, and gonadotrophin-releasing hormonal-neuronal migration. Insofar as the CaSR is a clinically important therapeutic target for parathyroid disorders, development of its agonists or antagonists as therapeutics for CNS disorder could be a major breakthrough.
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Affiliation(s)
- Sanghamitra Bandyopadhyay
- Developmental Toxicology, Indian Institute of Toxicology Research (Council of Scientific and Industrial Rsearch; CSIR), Lucknow, India
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Trivedi R, Goswami R, Chattopadhyay N. Investigational anabolic therapies for osteoporosis. Expert Opin Investig Drugs 2010; 19:995-1005. [PMID: 20629616 DOI: 10.1517/13543784.2010.501077] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
IMPORTANCE OF THE FIELD Anabolic therapy, or stimulating the function of bone-forming osteoblasts, is the preferred pharmacological intervention for osteoporosis. AREAS COVERED IN THIS REVIEW We reviewed bone anabolic agents currently under active investigation. The bone anabolic potential of IGF-I and parathyroid hormone-related protein is discussed in the light of animal data and human studies. We also discuss the use of antagonists of the calcium-sensing receptor (calcilytics) as orally administered small molecules capable of transiently elevating serum parathyroid hormone (PTH). Further, we reviewed novel anabolic agents targeting members of the wingless tail (Wnt) signaling family that regulate bone formation including DKK-1, sclerostin, Thp1, and glycogen synthase kinase 3beta. We have also followed up on the promise shown by beta-blockers in modulating the activity of sympathetic nervous system, thus affecting bone anabolism. We give critical consideration to neutralizing the activity of activin A, a negative regulator of bone mass by soluble activin receptor IIA, as a strategy to promote bone formation. WHAT THE READER WILL GAIN Update on various strategies to promote osteoblast function currently under evaluation. TAKE HOME MESSAGE In spite of favorable results in experimental models, none of these strategies has yet achieved the ultimate goal of providing an alternative to injectable PTH, the sole anabolic therapy in clinical use.
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Affiliation(s)
- Ritu Trivedi
- Central Drug Research Institute (Council of Scientific and Industrial Research), Division of Endocrinology, Lucknow, India.
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50
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Dong Q, Cheng Z, Chang W, Blackman BE, Conte FA, Hu J, Shoback D, Miller WL. Naturally-occurring mutation in the calcium-sensing receptor reveals the significance of extracellular domain loop III region for class C G-protein-coupled receptor function. J Clin Endocrinol Metab 2010; 95:E245-52. [PMID: 20631026 PMCID: PMC3050095 DOI: 10.1210/jc.2010-0559] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Inactivating mutations of the calcium-sensing receptor (CaSR) cause familial hypocalciuric hypercalcemia and neonatal severe hyperparathyroidism. Most mutations are clustered in the N-terminal and Cys-rich regions of the extracellular domain (ECD) and seven-transmembrane domain. Disease-causing mutations are uncommon in the C terminus of ECD. OBJECTIVE The aim of the study was to characterize the CaSR mutations causing neonatal severe hyperparathyroidism in a consanguineous family. METHODS Parathyroid glands from the index patient were stained for CaSR protein. The CaSR gene was sequenced, mutations were recreated in CaSR cDNA, and HEK293 cells were transfected with the CaSR mutant expression vector. Cellular CaSR targeting was detected by immunoblotting and immunocytochemistry; CaSR activity was assayed by inositol phosphate accumulation, MAPK activation, and single-cell microfluorimetry. RESULTS Immunocytochemistry showed reduced intracellular CaSR in patient parathyroids. An in-frame homozygous deletion/insertion mutation, c.1031 > 1034 (delACAAinsT), replaced His344-Asn345 with a single Leu in CaSR loop III. The mutant reduced cell surface expression of CaSR in transfected HEK293 cells. Inositol phosphate accumulation, MAPK activation, and single-cell microfluorimetry revealed blunted signaling responses of the mutant receptor to changes in extracellular Ca(2+) concentration. CONCLUSION Deletion of His344-Asn345 in the ECD loop III region affects cell surface targeting of CaSR in transfected cells and in affected parathyroid glands. Absence of conserved Asn345 may interfere with CaSR folding or glycosylation, leading to poor protein targeting to the cell membrane. This loss-of-function mutant indicates that the ECD loop III is required for CaSR activity.
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Affiliation(s)
- Qing Dong
- Department of Pediatrics, University of California, San Francisco, San Francisco, California 94143-0434, USA.
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