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Baranes K, Hastings N, Rahman S, Poulin N, Tavares JM, Kuan W, Syed N, Kunz M, Blighe K, Belgard TG, Kotter MRN. Transcription factor combinations that define human astrocyte identity encode significant variation of maturity and function. Glia 2023; 71:1870-1889. [PMID: 37029764 PMCID: PMC10952910 DOI: 10.1002/glia.24372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 03/13/2023] [Accepted: 03/20/2023] [Indexed: 04/09/2023]
Abstract
Increasing evidence indicates that cellular identity can be reduced to the distinct gene regulatory networks controlled by transcription factors (TFs). However, redundancy exists in these states as different combinations of TFs can induce broadly similar cell types. We previously demonstrated that by overcoming gene silencing, it is possible to deterministically reprogram human pluripotent stem cells directly into cell types of various lineages. In the present study we leverage the consistency and precision of our approach to explore four different TF combinations encoding astrocyte identity, based on previously published reports. Analysis of the resulting induced astrocytes (iAs) demonstrated that all four cassettes generate cells with the typical morphology of in vitro astrocytes, which expressed astrocyte-specific markers. The transcriptional profiles of all four iAs clustered tightly together and displayed similarities with mature human astrocytes, although maturity levels differed between cells. Importantly, we found that the TF cassettes induced iAs with distinct differences with regards to their cytokine response and calcium signaling. In vivo transplantation of selected iAs into immunocompromised rat brains demonstrated long term stability and integration. In conclusion, all four TF combinations were able to induce stable astrocyte-like cells that were morphologically similar but showed subtle differences with respect to their transcriptome. These subtle differences translated into distinct differences with regards to cell function, that could be related to maturation state and/or regional identity of the resulting cells. This insight opens an opportunity to precision-engineer cells to meet functional requirements, for example, in the context of therapeutic cell transplantation.
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Affiliation(s)
- Koby Baranes
- Department of Clinical NeurosciencesUniversity of CambridgeCambridgeCB2 0QQUK
- Wellcome‐MRC Cambridge Stem Cell Institute, University of CambridgeCambridgeCB2 0AWUK
| | - Nataly Hastings
- Department of Clinical NeurosciencesUniversity of CambridgeCambridgeCB2 0QQUK
- Wellcome‐MRC Cambridge Stem Cell Institute, University of CambridgeCambridgeCB2 0AWUK
| | - Saifur Rahman
- Department of Clinical NeurosciencesUniversity of CambridgeCambridgeCB2 0QQUK
- Wellcome‐MRC Cambridge Stem Cell Institute, University of CambridgeCambridgeCB2 0AWUK
| | - Noah Poulin
- Department of Clinical NeurosciencesUniversity of CambridgeCambridgeCB2 0QQUK
- Wellcome‐MRC Cambridge Stem Cell Institute, University of CambridgeCambridgeCB2 0AWUK
| | - Joana M. Tavares
- Department of Clinical NeurosciencesUniversity of CambridgeCambridgeCB2 0QQUK
- Wellcome‐MRC Cambridge Stem Cell Institute, University of CambridgeCambridgeCB2 0AWUK
| | - Wei‐Li Kuan
- Department of Clinical NeurosciencesUniversity of CambridgeCambridgeCB2 0QQUK
| | - Najeeb Syed
- The Bioinformatics CROSanfordFlorida32771USA
| | - Meik Kunz
- The Bioinformatics CROSanfordFlorida32771USA
| | | | | | - Mark R. N. Kotter
- Department of Clinical NeurosciencesUniversity of CambridgeCambridgeCB2 0QQUK
- Wellcome‐MRC Cambridge Stem Cell Institute, University of CambridgeCambridgeCB2 0AWUK
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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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Goralski T, Ram JL. Extracellular Calcium Receptor as a Target for Glutathione and Its Derivatives. Int J Mol Sci 2022; 23:ijms23020717. [PMID: 35054903 PMCID: PMC8776003 DOI: 10.3390/ijms23020717] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 01/03/2022] [Accepted: 01/05/2022] [Indexed: 12/16/2022] Open
Abstract
Extracellular glutathione (GSH) and oxidized glutathione (GSSG) can modulate the function of the extracellular calcium sensing receptor (CaSR). The CaSR has a binding pocket in the extracellular domain of CaSR large enough to bind either GSH or GSSG, as well as the naturally occurring oxidized derivative L-cysteine glutathione disulfide (CySSG) and the compound cysteinyl glutathione (CysGSH). Modeling the binding energies (ΔG) of CySSG and CysGSH to CaSR reveals that both cysteine derivatives may have greater affinities for CaSR than either GSH or GSSG. GSH, CySSG, and GSSG are found in circulation in mammals and, among the three, CySSG is more affected by HIV/AIDs and aging than either GSH or GSSG. The beta-carbon linkage of cysteine in CysGSH may model a new class of calcimimetics, exemplified by etelcalcetide. Circulating glutathionergic compounds, particularly CySSG, may mediate calcium-regulatory responses via receptor-binding to CaSR in a variety of organs, including parathyroids, kidneys, and bones. Receptor-mediated actions of glutathionergics may thus complement their roles in redox regulation and detoxification. The glutathionergic binding site(s) on CaSR are suggested to be a target for development of drugs that can be used in treating kidney and other diseases whose mechanisms involve CaSR dysregulation.
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Affiliation(s)
- Thomas Goralski
- Department of Physiology, Wayne State University, Detroit, MI 48201, USA;
- Van Andel Institute, Grand Rapids, MI 49503, USA
| | - Jeffrey L. Ram
- Department of Physiology, Wayne State University, Detroit, MI 48201, USA;
- Correspondence: ; Tel.: +1-248-200-9431
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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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Kinetic mechanisms by which nickel alters the calcium (Ca 2+) transport in intact rat liver. J Biol Inorg Chem 2021; 26:641-658. [PMID: 34304317 DOI: 10.1007/s00775-021-01883-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Accepted: 07/14/2021] [Indexed: 10/20/2022]
Abstract
In the present work, the multiple-indicator dilution (MID) technique was used to investigate the kinetic mechanisms by which nickel (Ni2+) affects the calcium (Ca2+) transport in intact rat liver. 45Ca2+ and extra- and intracellular space indicators were injected in livers perfused with 1 mM Ni2+, and the outflow profiles were analyzed by a mathematical model. For comparative purposes, the effects of norepinephrine were measured. The influence of Ni2+ on the cytosolic Ca2+ concentration ([Ca2+]c) in human hepatoma Huh7 cells and on liver glycogen catabolism, a biological response sensitive to cellular Ca2+, was also evaluated. The estimated transfer coefficients of 45Ca2+ transport indicated two mechanisms by which Ni2+ increases the [Ca2+]c in liver under steady-state conditions: (1) an increase in the net efflux of Ca2+ from intracellular Ca2+ stores due to a stimulus of Ca2+ efflux to the cytosolic space along with a diminution of Ca2+ re-entry into the cellular Ca2+ stores; (2) a decrease in Ca2+ efflux from the cytosolic space to vascular space, minimizing Ca2+ loss. Glycogen catabolism activated by Ni2+ was transient contrasting with the sustained activation induced by norepinephrine. Ni2+ caused a partial reduction in the norepinephrine-induced stimulation in the [Ca2+]c in Huh7 cells. Our data revealed that the kinetic parameters of Ca2+ transport modified by Ni2+ in intact liver are similar to those modified by norepinephrine in its first minutes of action, but the membrane receptors or Ca2+ transporters affected by Ni2+ seem to be distinct from those known to be modulated by norepinephrine.
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Liu W, Guo Y, Liu Y, Sun J, Yin X. Calcium-Sensing Receptor of Immune Cells and Diseases. CARDIOVASCULAR INNOVATIONS AND APPLICATIONS 2021. [DOI: 10.15212/cvia.2021.0009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Calcium-sensing receptor (CaSR), which was initially found in the parathyroid gland, is ubiquitously expressed and exerts specific functions in multiple cells, including immune cells. CaSR is functionally expressed on neutrophils, monocytes/macrophages, and T lymphocytes, but not B
lymphocytes, and regulates cell functions, such as cytokine secretion, chemotaxis, phenotype switching, and ligand delivery. In these immune cells, CaSR is involved in the development of many diseases, such as sepsis, cryopyrin-associated periodic syndromes, rheumatism, myocardial infarction,
diabetes, and peripheral artery disease. Since its discovery, it has been controversial whether CaSR is expressed and plays a role in immune cells. This article reviews current knowledge of the role of CaSR in immune cells.
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Affiliation(s)
- Wenxiu Liu
- Department of Cardiology, The First Affiliated Hospital of Harbin Medical University, Harbin, 150001 Heilongjiang, China
| | - Yutong Guo
- Department of Cardiology, The First Affiliated Hospital of Harbin Medical University, Harbin, 150001 Heilongjiang, China
| | - Yue Liu
- Department of Cardiology, The First Affiliated Hospital of Harbin Medical University, Harbin, 150001 Heilongjiang, China
| | - Jiaxing Sun
- Department of Cardiology, The First Affiliated Hospital of Harbin Medical University, Harbin, 150001 Heilongjiang, China
| | - Xinhua Yin
- Department of Cardiology, The First Affiliated Hospital of Harbin Medical University, Harbin, 150001 Heilongjiang, China
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Ahmad R, Dalziel JE. G Protein-Coupled Receptors in Taste Physiology and Pharmacology. Front Pharmacol 2020; 11:587664. [PMID: 33390961 PMCID: PMC7774309 DOI: 10.3389/fphar.2020.587664] [Citation(s) in RCA: 88] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 10/09/2020] [Indexed: 12/14/2022] Open
Abstract
Heterotrimeric G protein-coupled receptors (GPCRs) comprise the largest receptor family in mammals and are responsible for the regulation of most physiological functions. Besides mediating the sensory modalities of olfaction and vision, GPCRs also transduce signals for three basic taste qualities of sweet, umami (savory taste), and bitter, as well as the flavor sensation kokumi. Taste GPCRs reside in specialised taste receptor cells (TRCs) within taste buds. Type I taste GPCRs (TAS1R) form heterodimeric complexes that function as sweet (TAS1R2/TAS1R3) or umami (TAS1R1/TAS1R3) taste receptors, whereas Type II are monomeric bitter taste receptors or kokumi/calcium-sensing receptors. Sweet, umami and kokumi receptors share structural similarities in containing multiple agonist binding sites with pronounced selectivity while most bitter receptors contain a single binding site that is broadly tuned to a diverse array of bitter ligands in a non-selective manner. Tastant binding to the receptor activates downstream secondary messenger pathways leading to depolarization and increased intracellular calcium in TRCs, that in turn innervate the gustatory cortex in the brain. Despite recent advances in our understanding of the relationship between agonist binding and the conformational changes required for receptor activation, several major challenges and questions remain in taste GPCR biology that are discussed in the present review. In recent years, intensive integrative approaches combining heterologous expression, mutagenesis and homology modeling have together provided insight regarding agonist binding site locations and molecular mechanisms of orthosteric and allosteric modulation. In addition, studies based on transgenic mice, utilizing either global or conditional knock out strategies have provided insights to taste receptor signal transduction mechanisms and their roles in physiology. However, the need for more functional studies in a physiological context is apparent and would be enhanced by a crystallized structure of taste receptors for a more complete picture of their pharmacological mechanisms.
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Affiliation(s)
- Raise Ahmad
- Food Nutrition and Health Team, Food and Bio-based Products Group, AgResearch, Palmerston North, New Zealand
| | - Julie E Dalziel
- Food Nutrition and Health Team, Food and Bio-based Products Group, AgResearch, Palmerston North, New Zealand
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Ran D, Liu W, Ma Y, Zheng J, Wang D, Song R, Zou H, Gu J, Bian J, Yuan Y, Liu Z. Role of calcium-sensing receptor in cadmium-induced apoptosis of rat primary osteoblasts in vitro. Toxicol In Vitro 2020; 67:104923. [PMID: 32599263 DOI: 10.1016/j.tiv.2020.104923] [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: 05/10/2020] [Revised: 06/11/2020] [Accepted: 06/17/2020] [Indexed: 10/24/2022]
Abstract
Calcium is essential to various physiological and pathophysiological cellular processes. Calcium-sensing receptor (CasR), a seven-transmembrane-spanning protein that responds to changes in extracellular Ca2+, partly modulates calcium homeostasis, thereby influencing bone metabolism. In this study, we aimed to elucidate the role of CasR in Cd-induced calcium homeostasis disruption and OB apoptosis, and the underlying mechanisms. Cd treatment dramatically increased the protein expression of CasR and elevated the intracellular calcium concentration. Meanwhile, OBs apoptosis rate and caspase-dependent apoptosis protein levels, including cleaved caspase 3, cleaved caspase 9 and the ratio of Bax/Bcl-2 were increased. However, downregulation of CasR by CasR siRNA effectively suppressed the effects of Cd on theses phenomena. At the same time, we illustrated that CasR siRNA pretreatment blocked Cd-inhibited the phosphorylation of PKC and decreased Cd-induced the phosphorylation of PI3K/AKT. Our results suggested that CasR-mediated PKC and PI3K/AKT signaling pathways involve in calcium oscillation and apoptosis in OB caused by Cd maybe responsible for the bone homeostasis.
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Affiliation(s)
- Di Ran
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, PR China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu 225009, PR China; Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education of China, Yangzhou University, PR China
| | - Wei Liu
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, PR China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu 225009, PR China; Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education of China, Yangzhou University, PR China
| | - Yonggang Ma
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, PR China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu 225009, PR China; Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education of China, Yangzhou University, PR China
| | - Jiaming Zheng
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, PR China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu 225009, PR China; Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education of China, Yangzhou University, PR China
| | - Dedong Wang
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, PR China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu 225009, PR China; Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education of China, Yangzhou University, PR China
| | - Ruilong Song
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, PR China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu 225009, PR China; Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education of China, Yangzhou University, PR China
| | - Hui Zou
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, PR China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu 225009, PR China; Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education of China, Yangzhou University, PR China
| | - Jianhong Gu
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, PR China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu 225009, PR China; Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education of China, Yangzhou University, PR China
| | - Jianchun Bian
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, PR China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu 225009, PR China; Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education of China, Yangzhou University, PR China
| | - Yan Yuan
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, PR China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu 225009, PR China; Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education of China, Yangzhou University, PR China
| | - Zongping Liu
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, PR China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu 225009, PR China; Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education of China, Yangzhou University, PR China.
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van der Wijst J, Belge H, Bindels RJM, Devuyst O. Learning Physiology From Inherited Kidney Disorders. Physiol Rev 2019; 99:1575-1653. [PMID: 31215303 DOI: 10.1152/physrev.00008.2018] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The identification of genes causing inherited kidney diseases yielded crucial insights in the molecular basis of disease and improved our understanding of physiological processes that operate in the kidney. Monogenic kidney disorders are caused by mutations in genes coding for a large variety of proteins including receptors, channels and transporters, enzymes, transcription factors, and structural components, operating in specialized cell types that perform highly regulated homeostatic functions. Common variants in some of these genes are also associated with complex traits, as evidenced by genome-wide association studies in the general population. In this review, we discuss how the molecular genetics of inherited disorders affecting different tubular segments of the nephron improved our understanding of various transport processes and of their involvement in homeostasis, while providing novel therapeutic targets. These include inherited disorders causing a dysfunction of the proximal tubule (renal Fanconi syndrome), with emphasis on epithelial differentiation and receptor-mediated endocytosis, or affecting the reabsorption of glucose, the handling of uric acid, and the reabsorption of sodium, calcium, and magnesium along the kidney tubule.
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Affiliation(s)
- Jenny van der Wijst
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center , Nijmegen , The Netherlands ; Institute of Physiology, University of Zurich , Zurich , Switzerland ; and Division of Nephrology, Institute of Experimental and Clinical Research (IREC), Medical School, Université catholique de Louvain, Brussels, Belgium
| | - Hendrica Belge
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center , Nijmegen , The Netherlands ; Institute of Physiology, University of Zurich , Zurich , Switzerland ; and Division of Nephrology, Institute of Experimental and Clinical Research (IREC), Medical School, Université catholique de Louvain, Brussels, Belgium
| | - René J M Bindels
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center , Nijmegen , The Netherlands ; Institute of Physiology, University of Zurich , Zurich , Switzerland ; and Division of Nephrology, Institute of Experimental and Clinical Research (IREC), Medical School, Université catholique de Louvain, Brussels, Belgium
| | - Olivier Devuyst
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center , Nijmegen , The Netherlands ; Institute of Physiology, University of Zurich , Zurich , Switzerland ; and Division of Nephrology, Institute of Experimental and Clinical Research (IREC), Medical School, Université catholique de Louvain, Brussels, Belgium
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10
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Odutola SO, Bridges LE, Awumey EM. Protein Kinase C Downregulation Enhanced Extracellular Ca 2+-Induced Relaxation of Isolated Mesenteric Arteries from Aged Dahl Salt-Sensitive Rats. J Pharmacol Exp Ther 2019; 370:427-435. [PMID: 31197021 DOI: 10.1124/jpet.119.258475] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Accepted: 06/10/2019] [Indexed: 12/20/2022] Open
Abstract
The Ca2+-sensing receptor (CaSR) detects small changes in extracellular calcium (Ca2+ e) concentration ([Ca2+]e) and transduces the signal into modulation of various signaling pathways. Ca2+-induced relaxation of isolated phenylephrine-contracted mesenteric arteries is mediated by the CaSR of the perivascular nerve. Elucidation of the regulatory mechanisms involved in vascular CaSR signaling may provide insights into the physiologic functions of the receptor and identify targets for the development of new treatments for cardiovascular pathologies such as hypertension. Protein kinase Cα (PKCα) is a critical regulator of multiple signaling pathways and can phosphorylate the CaSR leading to receptor desensitization. In this study, we used automated wire myography to investigate the effects of CaSR mutation and small-interfering RNA downregulation of PKCα on CaSR-mediated relaxation of phenylephrine-contracted mesenteric arteries from aged Dahl salt-sensitive (SS) rats on a low-salt diet. The data showed minimal relaxation responses of arteries to Ca2+ e in wild-type (SS) and CaSR mutant (SS-Casrem1Mcwi) rats. Mutation of the CaSR gene had no significant effect on relaxation. PKCα expression was similar in wild-type and mutant rats, and small-interfering RNA downregulation of PKCα and/or inhibition of PKC with the Ca2+-sensitive Gӧ 6976 resulted in a >80% increase in relaxation. Significant differences in EC50 values were observed between treated and untreated controls (P < 0.05 analysis of variance). The results indicate that PKCα plays an important role in the regulation of CaSR-mediated relaxation of mesenteric arteries, and its downregulation or pharmacological inhibition may lead to an increased Ca2+ sensitivity of the receptor and reversal of age-related changes in vascular tone. SIGNIFICANCE STATEMENT: G protein-coupled CaSR signaling leads to the regulation of vascular tone and may, therefore, play a vital role in blood pressure regulation. The receptor has several PKC phosphorylation sites in the C-terminal intracellular tail that mediate desensitization. We have previously shown that activation of the CaSR in neuronal cells leads to PKC phosphorylation, indicating that protein kinase C is an important regulator of CaSR function. Therefore, PKC in the CaSR signaling pathway in mesenteric arteries is a potential target for the development of new therapeutic approaches to treat hypertension and age-related vascular dysfunction. The present studies show that small-interfering RNA downregulation of PKCα and pharmacological inhibition of PKC enhanced CaSR-mediated relaxation of phenylephrine-contracted mesenteric arteries from aged Dahl salt-sensitive rats.
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Affiliation(s)
- Samuel O Odutola
- Julius L. Chambers Biomedical/Biotechnology Research Institute (S.O.O., L.E.B., E.M.A.) and Department of Biological and Biomedical Sciences (E.M.A), North Carolina Central University, Durham, North Carolina; and Department of Physiology and Pharmacology, Hypertension and Vascular Research Center, Wake Forest University School of Medicine, Winston-Salem, North Carolina (E.M.A.)
| | - Lakeesha E Bridges
- Julius L. Chambers Biomedical/Biotechnology Research Institute (S.O.O., L.E.B., E.M.A.) and Department of Biological and Biomedical Sciences (E.M.A), North Carolina Central University, Durham, North Carolina; and Department of Physiology and Pharmacology, Hypertension and Vascular Research Center, Wake Forest University School of Medicine, Winston-Salem, North Carolina (E.M.A.)
| | - Emmanuel M Awumey
- Julius L. Chambers Biomedical/Biotechnology Research Institute (S.O.O., L.E.B., E.M.A.) and Department of Biological and Biomedical Sciences (E.M.A), North Carolina Central University, Durham, North Carolina; and Department of Physiology and Pharmacology, Hypertension and Vascular Research Center, Wake Forest University School of Medicine, Winston-Salem, North Carolina (E.M.A.)
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Abstract
Hypocalcemia and hyperphosphatemia are the pathognomonic biochemical features of hypoparathyroidism, and result directly from lack of parathyroid hormone (PTH) action on the kidney. In the absence of PTH action, the renal mechanisms transporting calcium and phosphate reabsorption deregulate, resulting in hypocalcemia and hyperphosphatemia. Circulating calcium negatively regulates PTH secretion. Hypocalcemia causes neuromuscular disturbances ranging from epilepsy and tetany to mild paresthesia. Circulating phosphate concentration does not directly regulate PTH secretion. Hyperphosphatemia is subclinical, but chronically promotes ectopic mineralization disease. Vitamin D-thiazide treatment leads to ectopic mineralization and renal damage. PTH treatment has the potential for fewer side effects.
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Affiliation(s)
- Munro Peacock
- Department of Medicine, Division of Endocrinology, Indiana University School of Medicine, 1120 West Michigan Street Cl 365, Indianapolis, IN 46202, USA.
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Capozza M, Chinellato I, Guarnieri V, Di Lorgi N, Accadia M, Traggiai C, Mattioli G, Di Mauro A, Laforgia N. Case report: acute clinical presentation and neonatal management of primary hyperparathyroidism due to a novel CaSR mutation. BMC Pediatr 2018; 18:340. [PMID: 30376845 PMCID: PMC6208175 DOI: 10.1186/s12887-018-1319-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 10/23/2018] [Indexed: 11/18/2022] Open
Abstract
Background Neonatal severe primary hyperparathyroidism (NSHPT) is a rare autosomal recessive disorder of calcium homeostasis, characterized by striking hyperparathyroidism, marked hypercalcemia and hyperparathyroid bone disease. We report the case of a newborn with a novel homozygous mutation of the CaSR, treated by successful subtotal parathyroidectomy, who had an acute presentation of the disease, i.e. out-of hospital cardiorespiratory arrest. . Case presentation A 8-day-old female newborn was admitted to the NICU of University of Bari “Aldo Moro” (Italy) after a cardiorespiratory arrest occurred at home. Severe hypercalcemia was found and different drug therapies were employed (Furosemide, Cinacalcet and bisphosphonate), as well as hyperhydration, until subtotal parathyroidectomy, was performed at day 32. Our patient’s mutation was never described before so that a strict and individualized long-term follow-up was started. Conclusions This case of NSHPT suggests that a near-miss event, labelled as a possible case of SIDS, could also be due to severe hypercalcemia and evidentiates the difficulties of the neonatal management of NSHPT. Furthermore, the identification of the specific CaSR mutation provides the substrate for prenatal diagnosis.
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Affiliation(s)
- Manuela Capozza
- Neonatology and Neonatal Intensive Care Unit, Department of Biomedical Science ad Human Oncology, University of Bari "Aldo Moro", Bari, Italy. .,Policlinico Hospital, Piazza Giulio Cesare n. 11, 70124, Bari, Italy.
| | | | - Vito Guarnieri
- Medical Genetics, IRCCS Casa Sollievo della Sofferenza Hospital, San Giovanni Rotondo, Foggia, Italy
| | - Natascia Di Lorgi
- Department of Pediatrics, Endocrine, Diabetes and Metabolic Unit, Istituto Giannina Gaslini, University of Genova, Genoa, Italy
| | - Maria Accadia
- Medical Genetics, IRCCS Casa Sollievo della Sofferenza Hospital, San Giovanni Rotondo, Foggia, Italy
| | - Cristina Traggiai
- Neonatology and Neonatal Intensive Care Unit, Istituto Giannina Gaslini, Genoa, Italy
| | - Girolamo Mattioli
- Pediatric Surgery Unit, Istituto Giannina Gaslini, University of Genoa, Genoa, Italy
| | - Antonio Di Mauro
- Neonatology and Neonatal Intensive Care Unit, Department of Biomedical Science ad Human Oncology, University of Bari "Aldo Moro", Bari, Italy
| | - Nicola Laforgia
- Neonatology and Neonatal Intensive Care Unit, Department of Biomedical Science ad Human Oncology, University of Bari "Aldo Moro", Bari, Italy
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Abstract
Calcium is vital for life, and extracellular calcium concentrations must constantly be maintained within a precise concentration range. Low serum calcium (hypocalcemia) occurs in conjunction with multiple disorders and can be life-threatening if severe. Symptoms of acute hypocalcemia include neuromuscular irritability, tetany, and seizures, which are rapidly resolved with intravenous administration of calcium gluconate. However, disorders that lead to chronic hypocalcemia often have more subtle manifestations. Hypoparathyroidism, characterized by impaired secretion of parathyroid hormone (PTH), a key regulatory hormone for maintaining calcium homeostasis, is a classic cause of chronic hypocalcemia. Disorders that disrupt the metabolism of vitamin D can also lead to chronic hypocalcemia, as vitamin D is responsible for increasing the gut absorption of dietary calcium. Treatment and management options for chronic hypocalcemia vary depending on the underlying disorder. For example, in patients with hypoparathyroidism, calcium and vitamin D supplementation must be carefully titrated to avoid symptoms of hypocalcemia while keeping serum calcium in the low-normal range to minimize hypercalciuria, which can lead to renal dysfunction. Management of chronic hypocalcemia requires knowledge of the factors that influence the complex regulatory axes of calcium homeostasis in a given disorder. This chapter discusses common and rare disorders of hypocalcemia, symptoms and workup, and management options including replacement of PTH in hypoparathyroidism.
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Affiliation(s)
- Erin Bove-Fenderson
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Thier 1101, 50 Blossom St, Boston, MA, 02114, USA
| | - Michael Mannstadt
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Thier 1101, 50 Blossom St, Boston, MA, 02114, USA.
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Dos Santos PMC, Amaral D, Tararthuch AL, Fernandez R. Calcium-sensing receptor (CaSR) modulates vacuolar H +-ATPase activity in a cell model of proximal tubule. Clin Exp Nephrol 2018; 22:1258-1265. [PMID: 29961155 DOI: 10.1007/s10157-018-1613-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Accepted: 06/18/2018] [Indexed: 10/28/2022]
Abstract
BACKGROUND The calcium-sensing receptor (CaSR) is localized in the apical membrane of proximal tubules in close proximity to the transporters responsible for proton secretion. Therefore, the aim of the present study was to analyze the effects of CaSR stimulation on the biochemical activity of the vacuolar H+-ATPase in a cellular model of proximal tubule cells, OKP cells. METHODS Biochemical activity of H+-ATPase was performed using cell homogenates, and the inorganic phosphate released was determined by a colorimetric method. Changes in cytosolic ionized calcium [Ca2+]i were also determined using Fluo-4. RESULTS A significant increase of vacuolar H+-ATPase activity was observed when the CaSR was stimulated with agonists such as Gd3+ (300 µM) and neomycin (200 µM). This activity was also stimulated in a dose-dependent fashion by changes in extracellular Ca2+ (Ca2+o) between 10-4 and 2 mM. Gd3+ and neomycin produced a sustained rise of [Ca2+]i, an effect that disappears when extracellular calcium was removed in the presence of 0.1 µM thapsigargin. Inhibition of phospholipase C (PLC) activity with U73122 (5 × 10-8 M) reduced the increase in [Ca2+]i induced by neomycin. CONCLUSION CaSR stimulation induces an increase in the vacuolar H+-ATPase activity of OKP cells, an effect that involves an increase in [Ca2+]i and require phospholipase C activity. The consequent decrease in intratubular pH could lead to increase ionization of luminal calcium, potentially enhancing its reabsorption in distal tubule segments and reducing the formation of calcium phosphate stones.
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Affiliation(s)
- Priscilla Marys Costa Dos Santos
- Departamento de Fisiologia, Setor de Ciências Biológicas, UFPR, Centro Politécnico s/n., Jd. das Américas, Postal Box: 19031, Curitiba, PR, 81531-990, Brazil
| | - Deividi Amaral
- Departamento de Fisiologia, Setor de Ciências Biológicas, UFPR, Centro Politécnico s/n., Jd. das Américas, Postal Box: 19031, Curitiba, PR, 81531-990, Brazil
| | - Ana Lucia Tararthuch
- Departamento de Fisiologia, Setor de Ciências Biológicas, UFPR, Centro Politécnico s/n., Jd. das Américas, Postal Box: 19031, Curitiba, PR, 81531-990, Brazil
| | - Ricardo Fernandez
- Departamento de Fisiologia, Setor de Ciências Biológicas, UFPR, Centro Politécnico s/n., Jd. das Américas, Postal Box: 19031, Curitiba, PR, 81531-990, Brazil.
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15
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Bazúa-Valenti S, Rojas-Vega L, Castañeda-Bueno M, Barrera-Chimal J, Bautista R, Cervantes-Pérez LG, Vázquez N, Plata C, Murillo-de-Ozores AR, González-Mariscal L, Ellison DH, Riccardi D, Bobadilla NA, Gamba G. The Calcium-Sensing Receptor Increases Activity of the Renal NCC through the WNK4-SPAK Pathway. J Am Soc Nephrol 2018; 29:1838-1848. [PMID: 29848507 DOI: 10.1681/asn.2017111155] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Accepted: 04/10/2018] [Indexed: 01/07/2023] Open
Abstract
Background Hypercalciuria can result from activation of the basolateral calcium-sensing receptor (CaSR), which in the thick ascending limb of Henle's loop controls Ca2+ excretion and NaCl reabsorption in response to extracellular Ca2+ However, the function of CaSR in the regulation of NaCl reabsorption in the distal convoluted tubule (DCT) is unknown. We hypothesized that CaSR in this location is involved in activating the thiazide-sensitive NaCl cotransporter (NCC) to prevent NaCl loss.Methods We used a combination of in vitro and in vivo models to examine the effects of CaSR on NCC activity. Because the KLHL3-WNK4-SPAK pathway is involved in regulating NaCl reabsorption in the DCT, we assessed the involvement of this pathway as well.Results Thiazide-sensitive 22Na+ uptake assays in Xenopus laevis oocytes revealed that NCC activity increased in a WNK4-dependent manner upon activation of CaSR with Gd3+ In HEK293 cells, treatment with the calcimimetic R-568 stimulated SPAK phosphorylation only in the presence of WNK4. The WNK4 inhibitor WNK463 also prevented this effect. Furthermore, CaSR activation in HEK293 cells led to phosphorylation of KLHL3 and WNK4 and increased WNK4 abundance and activity. Finally, acute oral administration of R-568 in mice led to the phosphorylation of NCC.Conclusions Activation of CaSR can increase NCC activity via the WNK4-SPAK pathway. It is possible that activation of CaSR by Ca2+ in the apical membrane of the DCT increases NaCl reabsorption by NCC, with the consequent, well known decrease of Ca2+ reabsorption, further promoting hypercalciuria.
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Affiliation(s)
- Silvana Bazúa-Valenti
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico.,Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - Lorena Rojas-Vega
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - María Castañeda-Bueno
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - Jonatan Barrera-Chimal
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | | | | | - Norma Vázquez
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Consuelo Plata
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - Adrián R Murillo-de-Ozores
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico.,Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - Lorenza González-Mariscal
- Department of Physiology, Biophysics and Neuroscience, Center for Research and Advanced Studies (Cinvestav), Mexico City, Mexico
| | - David H Ellison
- Department of Medicine, Oregon Health and Science University, Portland, Oregon.,Renal Section, Veterans Administration Portland Health Care System, Portland, Oregon
| | - Daniela Riccardi
- School of Biosciences, Cardiff University, Cardiff, United Kingdom; and
| | - Norma A Bobadilla
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico.,Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - Gerardo Gamba
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico; .,Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico.,Tecnológico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Monterrey, Nuevo León, Mexico
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16
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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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17
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Gu J, Dai S, Liu Y, Liu H, Zhang Y, Ji X, Yu F, Zhou Y, Chen L, Tse WKF, Wong CKC, Chen B, Shi H. Activation of Ca 2+-sensing receptor as a protective pathway to reduce Cadmium-induced cytotoxicity in renal proximal tubular cells. Sci Rep 2018; 8:1092. [PMID: 29348484 PMCID: PMC5773512 DOI: 10.1038/s41598-018-19327-9] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Accepted: 12/27/2017] [Indexed: 01/16/2023] Open
Abstract
Cadmium (Cd), as an extremely toxic metal could accumulate in kidney and induce renal injury. Previous studies have proved that Cd impact on renal cell proliferation, autophagy and apoptosis, but the detoxification drugs and the functional mechanism are still in study. In this study, we used mouse renal tubular epithelial cells (mRTECs) to clarify Cd-induced toxicity and signaling pathways. Moreover, we proposed to elucidate the prevent effect of activation of Ca2+ sensing receptor (CaSR) by Calcimimetic (R-467) on Cd-induced cytotoxicity and underlying mechanisms. Cd induced intracellular Ca2+ elevation through phospholipase C-inositol 1, 4, 5-trisphosphate (PLC) followed stimulating p38 mitogen-activated protein kinases (MAPK) activation and suppressing extracellular signal-regulated kinase (ERK) activation, which leaded to increase apoptotic cell death and inhibit cell proliferation. Cd induced p38 activation also contribute to autophagic flux inhibition that aggravated Cd induced apoptosis. R-467 reinstated Cd-induced elevation of intracellular Ca2+ and apoptosis, and it also increased cell proliferation and restored autophagic flux by switching p38 to ERK pathway. The identification of the activation of CaSR-mediated protective pathway in renal cells sheds light on a possible cellular protective mechanism against Cd-induced kidney injury.
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Affiliation(s)
- Jie Gu
- Institute of Life Science, Jiangsu University, Zhenjiang, Jiangsu, 212000, China
| | - Shuya Dai
- Institute of Life Science, Jiangsu University, Zhenjiang, Jiangsu, 212000, China
| | - Yanmin Liu
- Institute of Life Science, Jiangsu University, Zhenjiang, Jiangsu, 212000, China
| | - Haitao Liu
- Institute of Life Science, Jiangsu University, Zhenjiang, Jiangsu, 212000, China
| | - Yao Zhang
- Medical Section, The Third Affiliated Hospital of Jiangsu University, Zhenjiang, Jiangsu, 212000, China
| | - Xingqi Ji
- Institute of Life Science, Jiangsu University, Zhenjiang, Jiangsu, 212000, China
| | - Feng Yu
- Institute of Life Science, Jiangsu University, Zhenjiang, Jiangsu, 212000, China
| | - Yang Zhou
- Institute of Life Science, Jiangsu University, Zhenjiang, Jiangsu, 212000, China
| | - Liang Chen
- Institute of Life Science, Jiangsu University, Zhenjiang, Jiangsu, 212000, China
| | | | - Chris Kong Chu Wong
- Department of Biology, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China
| | - Binghai Chen
- Department of urology, Affiliated Hospital of Jiangsu University, Zhenjiang, Jiangsu, 212000, China
| | - Haifeng Shi
- Institute of Life Science, Jiangsu University, Zhenjiang, Jiangsu, 212000, China.
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18
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Rasmussen AQ, Jørgensen NR, Schwarz P. Identification and Functional Characterization of a Novel Mutation in the Human Calcium-Sensing Receptor That Co-Segregates With Autosomal-Dominant Hypocalcemia. Front Endocrinol (Lausanne) 2018; 9:200. [PMID: 29743878 PMCID: PMC5930847 DOI: 10.3389/fendo.2018.00200] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 04/10/2018] [Indexed: 12/31/2022] Open
Abstract
The human calcium-sensing receptor (CASR) is the key controller of extracellular Cao2+ homeostasis, and different mutations in the CASR gene have been linked to different calcium diseases, such as familial hypocalciuric hypercalcemia, severe hyperparathyroidism, autosomal-dominant hypocalcemia (ADH), and Bartter's syndrome type V. In this study, two generations of a family with biochemically and clinically confirmed ADH who suffered severe muscle pain, arthralgia, tetany, abdominal pain, and fatigue were evaluated for mutations in the CASR gene. The study comprises genotyping of all family members, functional characterization of a potential mutant receptor by in vitro analysis related to the wild-type receptor to reveal an association between the genotype and phenotype in the affected family members. The in vitro analysis of functional characteristics includes measurements of inositol trisphosphate accumulation, Ca2+ mobilization in response to [Ca2+]o-stimulation and receptor expression. The results reveal a significant leftward shift of inositol trisphosphate accumulation as a result of the "gain-of-function" mutant receptor and surprisingly a normalization of the response in (Ca2+)i release in the downstream pathway and additionally the maximal response of (Ca2+)i release was significantly decreased compared to the wild type. However, no gross differences were seen in D126V and the D126V/WT CASR dimeric >250 kDa band expression compared to the WT receptor, however, the D126V and D126V/WT CASR immature ~140 kDa species appear to have reduced expression compared to the WT receptor. In conclusion, in this study, a family with a clinical diagnosis of ADH in two generations was evaluated to identify a mutation in the CASR gene and reveal an association between genotype and phenotype in the affected family members. The clinical condition was caused by a novel, activating, missense mutation (D126V) in the CASR gene and the in vitro functional characteristics of the mutation co-segregated with their individual phenotype.
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Affiliation(s)
- Anne Qvist Rasmussen
- Research Centre of Ageing and Osteoporosis, Department of Endocrinology, Rigshospitalet, Copenhagen, Denmark
- *Correspondence: Anne Qvist Rasmussen,
| | - Niklas Rye Jørgensen
- Department of Clinical Biochemistry, Rigshospitalet, Copenhagen, Denmark
- Institute of Clinical Research, University of Southern, Odense, Denmark
| | - Peter Schwarz
- Research Centre of Ageing and Osteoporosis, Department of Endocrinology, Rigshospitalet, Copenhagen, Denmark
- Faculty of Health Sciences, Copenhagen University, Copenhagen, Denmark
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19
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Bastepe M, Turan S, He Q. Heterotrimeric G proteins in the control of parathyroid hormone actions. J Mol Endocrinol 2017; 58:R203-R224. [PMID: 28363951 PMCID: PMC5650080 DOI: 10.1530/jme-16-0221] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 02/17/2017] [Indexed: 12/17/2022]
Abstract
Parathyroid hormone (PTH) is a key regulator of skeletal physiology and calcium and phosphate homeostasis. It acts on bone and kidney to stimulate bone turnover, increase the circulating levels of 1,25 dihydroxyvitamin D and calcium and inhibit the reabsorption of phosphate from the glomerular filtrate. Dysregulated PTH actions contribute to or are the cause of several endocrine disorders. This calciotropic hormone exerts its actions via binding to the PTH/PTH-related peptide receptor (PTH1R), which couples to multiple heterotrimeric G proteins, including Gs and Gq/11 Genetic mutations affecting the activity or expression of the alpha-subunit of Gs, encoded by the GNAS complex locus, are responsible for several human diseases for which the clinical findings result, at least partly, from aberrant PTH signaling. Here, we review the bone and renal actions of PTH with respect to the different signaling pathways downstream of these G proteins, as well as the disorders caused by GNAS mutations.
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Affiliation(s)
- Murat Bastepe
- Endocrine UnitDepartment of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA
| | - Serap Turan
- Department of Pediatric EndocrinologyMarmara University School of Medicine, Istanbul, Turkey
| | - Qing He
- Endocrine UnitDepartment of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA
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20
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Macías-García B, Lopes G, Rocha A, González-Fernández L. Role of the Calcium-Sensing Receptor (CaSR) in bovine gametes and during in vitro fertilization. Theriogenology 2017; 95:69-74. [PMID: 28460682 DOI: 10.1016/j.theriogenology.2017.03.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Revised: 02/15/2017] [Accepted: 03/06/2017] [Indexed: 01/22/2023]
Abstract
Calcium Sensing Receptor (CaSR) is a G-protein coupled receptor which senses extracellular calcium and activates diverse intracellular pathways. The objective of our work was to demonstrate the presence of CaSR in bovine gametes and its possible role in fertilization and embryo development. The location of CaSR was demonstrated by immunofluorescence in bovine gametes; additionally bovine sperm were incubated with 5, 10 and 15 μM of the specific CaSR inhibitor NPS2143 in a Tyrode's Albumin Lactate Pyruvate medium (4 h). Sperm viability was maintained for all concentrations tested while total motility decreased significantly at 10 and 15 μM. Addition of 15 μM of NPS2143 during oocyte in vitro maturation did not alter the maturation rate. When NPS2143 (15 μM) was added to the fertilization medium during sperm-oocyte co-incubation the cleavage, morula and blastocyst rates remained unchanged. To confirm if 15 μM of NPS2143 exerted any effect on embryo development, NPS2143 was added to the embryo culture medium. Cleavage rates remained unchanged when 15 μM of NPS2143 was added to the culture medium (79.1 ± 6.8 vs. 73.7 ± 5.3; mean % ± SEM; p > 0.05, control vs. inhibitor). By contrast, development to the morula (46.6 ± 7.3 vs. 24.3 ± 4.3; mean % ± SEM; p < 0.05) and blastocyst stages (29.9 ± 9.0 vs. 9.9 ± 3.6; mean % ± SEM; p < 0.05) decreased (control vs. inhibitor). Our results demonstrate a key role of CaSR on sperm motility and embryo development but not on oocyte maturation or fertilization in the bovine species.
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Affiliation(s)
- Beatriz Macías-García
- CECA/ICETA - Animal Sciences Centre, ICBAS - Abel Salazar Biomedical Institute, University of Porto, Portugal; Assisted Reproduction Unit, Minimally Invasive Surgery Centre Jesús Usón (CCMIJU), Cáceres, Spain
| | - Graça Lopes
- CECA/ICETA - Animal Sciences Centre, ICBAS - Abel Salazar Biomedical Institute, University of Porto, Portugal
| | - Antonio Rocha
- CECA/ICETA - Animal Sciences Centre, ICBAS - Abel Salazar Biomedical Institute, University of Porto, Portugal
| | - Lauro González-Fernández
- CECA/ICETA - Animal Sciences Centre, ICBAS - Abel Salazar Biomedical Institute, University of Porto, Portugal.
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21
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Activation of the Ca 2+-sensing receptors increases currents through inward rectifier K + channels via activation of phosphatidylinositol 4-kinase. Pflugers Arch 2016; 468:1931-1943. [PMID: 27838849 PMCID: PMC5138266 DOI: 10.1007/s00424-016-1901-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2016] [Revised: 10/26/2016] [Accepted: 11/06/2016] [Indexed: 10/25/2022]
Abstract
Inward rectifier K+ channels are important for maintaining normal electrical function in many cell types. The proper function of these channels requires the presence of membrane phosphoinositide 4,5-bisphosphate (PIP2). Stimulation of the Ca2+-sensing receptor CaR, a pleiotropic G protein-coupled receptor, activates both Gq/11, which decreases PIP2, and phosphatidylinositol 4-kinase (PI-4-K), which, conversely, increases PIP2. How membrane PIP2 levels are regulated by CaR activation and whether these changes modulate inward rectifier K+ are unknown. In this study, we found that activation of CaR by the allosteric agonist, NPSR568, increased inward rectifier K+ current (I K1) in guinea pig ventricular myocytes and currents mediated by Kir2.1 channels exogenously expressed in HEK293T cells with a similar sensitivity. Moreover, using the fluorescent PIP2 reporter tubby-R332H-cYFP to monitor PIP2 levels, we found that CaR activation in HEK293T cells increased membrane PIP2 concentrations. Pharmacological studies showed that both phospholipase C (PLC) and PI-4-K are activated by CaR stimulation with the latter played a dominant role in regulating membrane PIP2 and, thus, Kir currents. These results provide the first direct evidence that CaR activation upregulates currents through inward rectifier K+ channels by accelerating PIP2 synthesis. The regulation of I K1 plays a critical role in the stability of the electrical properties of many excitable cells, including cardiac myocytes and neurons. Further, synthetic allosteric modulators that increase CaR activity have been used to treat hyperparathyroidism, and negative CaR modulators are of potential importance in the treatment of osteoporosis. Thus, our results provide further insight into the roles played by CaR in the cardiovascular system and are potentially valuable for heart disease treatment and drug safety.
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22
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Zhang C, Miller CL, Gorkhali R, Zou J, Huang K, Brown EM, Yang JJ. Molecular Basis of the Extracellular Ligands Mediated Signaling by the Calcium Sensing Receptor. Front Physiol 2016; 7:441. [PMID: 27746744 PMCID: PMC5043022 DOI: 10.3389/fphys.2016.00441] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Accepted: 09/16/2016] [Indexed: 12/20/2022] Open
Abstract
Ca2+-sensing receptors (CaSRs) play a central role in regulating extracellular calcium concentration ([Ca2+]o) homeostasis and many (patho)physiological processes in multiple organs. This regulation is orchestrated by a cooperative response to extracellular stimuli such as small changes in Ca2+, Mg2+, amino acids, and other ligands. In addition, CaSR is a pleiotropic receptor regulating several intracellular signaling pathways, including calcium mobilization and intracellular calcium oscillation. Nearly 200 mutations and polymorphisms have been found in CaSR in relation to a variety of human disorders associated with abnormal Ca2+ homeostasis. In this review, we summarize efforts directed at identifying binding sites for calcium and amino acids. Both homotropic cooperativity among multiple calcium binding sites and heterotropic cooperativity between calcium and amino acid were revealed using computational modeling, predictions, and site-directed mutagenesis coupled with functional assays. The hinge region of the bilobed Venus flytrap (VFT) domain of CaSR plays a pivotal role in coordinating multiple extracellular stimuli, leading to cooperative responses from the receptor. We further highlight the extensive number of disease-associated mutations that have also been shown to affect CaSR's cooperative action via several types of mechanisms. These results provide insights into the molecular bases of the structure and functional cooperativity of this receptor and other members of family C of the G protein-coupled receptors (cGPCRs) in health and disease states, and may assist in the prospective development of novel receptor-based therapeutics.
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Affiliation(s)
- Chen Zhang
- Department of Chemistry, Georgia State University Atlanta, GA, USA
| | | | - Rakshya Gorkhali
- Department of Chemistry, Georgia State University Atlanta, GA, USA
| | - Juan Zou
- Department of Chemistry, Georgia State University Atlanta, GA, USA
| | - Kenneth Huang
- Department of Chemistry, Georgia State University Atlanta, GA, USA
| | - Edward M Brown
- Center for Diagnostics and Therapeutics, Georgia State UniversityAtlanta, GA, USA; Division of Endocrinology, Diabetes and Hypertension, Department of Medicine, Brigham and Women's HospitalBoston, MA, USA
| | - Jenny J Yang
- Department of Chemistry, Georgia State University Atlanta, GA, USA
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Yu J, Zhao L, Liu L, Yang F, Zhu X, Cao B. Tetrahydropalmatine protects rat pulmonary endothelial cells from irradiation-induced apoptosis by inhibiting oxidative stress and the calcium sensing receptor/phospholipase C-γ1 pathway. Free Radic Res 2016; 50:611-26. [PMID: 27134043 DOI: 10.3109/10715762.2016.1154549] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- J. Yu
- Department of Oncology, Beijing Friendship Hospital, Capital Medical University, Xicheng District, Beijing, P.R. China
| | - L. Zhao
- Department of Oncology, Beijing Friendship Hospital, Capital Medical University, Xicheng District, Beijing, P.R. China
| | - L. Liu
- Department of Oncology, Beijing Friendship Hospital, Capital Medical University, Xicheng District, Beijing, P.R. China
| | - F. Yang
- Department of Oncology, Beijing Friendship Hospital, Capital Medical University, Xicheng District, Beijing, P.R. China
| | - X. Zhu
- Department of Oncology, Guang An Men Hospital of Chinese Medica Science Research Institute, Xicheng District, Beijing, P.R. China
| | - B. Cao
- Department of Oncology, Beijing Friendship Hospital, Capital Medical University, Xicheng District, Beijing, P.R. China
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Regulation of α-Transducin and α-Gustducin Expression by a High Protein Diet in the Pig Gastrointestinal Tract. PLoS One 2016; 11:e0148954. [PMID: 26871573 PMCID: PMC4752509 DOI: 10.1371/journal.pone.0148954] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 01/25/2016] [Indexed: 11/29/2022] Open
Abstract
Background The expression of taste receptors (TASRs) and their signalling molecules in the gastrointestinal (GI) epithelial cells, including enteroendocrine cells (EECs), suggests they participate in chemosensing mechanisms influencing GI physiology via the release of endocrine messengers. TASRs mediate gustatory signalling by interacting with different transducers, including α-gustducin (Gαgust) and α-transducin (Gαtran) G protein subunits. This study tested whether Gαtran and Gαgust immunoreactive (-IR) cells are affected by a short-term (3 days) and long-term (30 days) high protein (Hp) diet in the pig GI tract. Result In the stomach, Gαgust and Gαtran-IR cells contained serotonin (5-HT) and ghrelin (GHR), while in the small and large intestine, Gαgust and Gαtran-IR colocalized with 5-HT-, cholecystokinin (CCK)- and peptide YY (PYY)-IR. There was a significant increase in the density of Gαtran-IR cells in the pyloric mucosa in both short- and long-term Hp diet groups (Hp3 and Hp30) vs. the control group (Ctr) (P<0.05), while the increase of Gαgust-IR cells in the pyloric mucosa was significant in Hp30 group vs. Ctr and vs. Hp3 (P<0.05); these cells included Gαtran / 5HT-IR and Gαtran / GHR-IR cells (P<0.05 and P<0.001 vs. Ctr, respectively) as well as Gαgust /5-HT-IR or Gαgust / GHR-IR cells (P<0.05 and P<0.01 vs. Ctr, respectively). In the small intestine, we recorded a significant increase in Gαtran-IR cells in the duodenal crypts and a significant increase of Gαgust-IR cells in the jejunal crypts in Hp3 group compared to HP30 (P<0.05). With regard to the number of Gαtran-Gαgust IR cells colocalized with CCK or 5-HT, there was only a significant increase of Gαtran / CCK-IR cells in Hp3 group compared to Ctr (P = 0.01). Conclusion This study showed an upregulation of selected subpopulations of Gαgust / Gαtran-IR cells in distinct regions of the pig GI tract by short- and long-term Hp diet lending support to TASR-mediated effects in metabolic homeostasis and satiety mechanisms.
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Owen JL, Cheng SX, Ge Y, Sahay B, Mohamadzadeh M. The role of the calcium-sensing receptor in gastrointestinal inflammation. Semin Cell Dev Biol 2015; 49:44-51. [PMID: 26709005 DOI: 10.1016/j.semcdb.2015.10.040] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 10/28/2015] [Accepted: 10/29/2015] [Indexed: 12/13/2022]
Abstract
The gastrointestinal (GI) tract must balance the extraction of energy and metabolic end-products from ingested nutrition and resident gut microbes and the maintenance of a symbiotic relationship with this microbiota, with the ability to mount functional immune responses to pathogenic organisms to maintain GI health. The gut epithelium is equipped with bacteria-sensing mechanisms that discriminate between pathogenic and commensal microorganisms and regulate host responses between immunity and tolerance. The epithelium also expresses numerous nutrient-sensing receptors, but their importance in the preservation of the gut microbiota and immune homeostasis remains largely unexplored. Observations that a deficiency in the extracellular calcium-sensing receptor (CaSR) using intestinal epithelium-specific receptor knockout mice resulted in diminished intestinal barrier integrity, altered composition of the gut microbiota, modified expression of intestinal pattern recognition receptors, and a skewing of local and systemic innate responses from regulatory to stimulatory, may change the way that this receptor is considered as a potential immunotherapeutic target in gut homeostasis. These findings suggest that pharmacologic CaSR activators and CaSR-based nutrients such as calcium, polyamines, phenylalanine, tryptophan, and oligo-peptides might be useful in conditioning the gut microenvironment, and thus, in the prevention and treatment of disorders such as inflammatory bowel disease (IBD), infectious enterocolitis, and other inflammatory and secretory diarrheal diseases. Here, we review the emerging roles of the CaSR in intestinal homeostasis and its therapeutic potential for gut pathology.
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Affiliation(s)
- Jennifer L Owen
- Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA
| | - Sam X Cheng
- Division of Gastroenterology, Department of Pediatrics, University of Florida, Gainesville, FL, USA
| | - Yong Ge
- Department of Infectious Diseases and Pathology, University of Florida, Gainesville, FL, USA; Division of Hepatology, Gastroenterology, and Nutrition, University of Florida, Gainesville, FL, USA
| | - Bikash Sahay
- Department of Infectious Diseases and Pathology, University of Florida, Gainesville, FL, USA; Division of Hepatology, Gastroenterology, and Nutrition, University of Florida, Gainesville, FL, USA
| | - Mansour Mohamadzadeh
- Department of Infectious Diseases and Pathology, University of Florida, Gainesville, FL, USA; Division of Hepatology, Gastroenterology, and Nutrition, University of Florida, Gainesville, FL, USA.
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Sesay JS, Gyapong RNK, Najafi LT, Kabler SL, Diz DI, Howlett AC, Awumey EM. Gαi/o-dependent Ca(2+) mobilization and Gαq-dependent PKCα regulation of Ca(2+)-sensing receptor-mediated responses in N18TG2 neuroblastoma cells. Neurochem Int 2015; 90:142-51. [PMID: 26190181 DOI: 10.1016/j.neuint.2015.07.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 06/24/2015] [Accepted: 07/14/2015] [Indexed: 01/14/2023]
Abstract
A functional Ca(2+)-sensing receptor (CaS) is expressed endogenously in mouse N18TG2 neuroblastoma cells, and sequence analysis of the cDNA indicates high homology with both rat and human parathyroid CaS cDNAs. The CaS in N18TG2 cells appears as a single immunoreactive protein band at about 150 kDa on Western blots, consistent with native CaS from dorsal root ganglia. Both wild type (WT) and Gαq antisense knock-down (KD) cells responded to Ca(2+) and calindol, a positive allosteric modulator of the CaS, with a transient increase in intracellular Ca(2+) concentration ([Ca(2+)]i), which was larger in the Gαq KD cells. Stimulation with 1 mM extracellular Ca(2+) (Ca(2+)e) increased [Ca(2+)]i in N18TG2 Gαq KD compared to WT cells. Ca(2+) mobilization was dependent on pertussis toxin-sensitive Gαi/o proteins and reduced by 30 μM 2-amino-ethyldiphenyl borate and 50 μM nifedipine to the same plateau levels in both cell types. Membrane-associated PKCα and p-PKCα increased with increasing [Ca(2+)]e in WT cells, but decreased in Gαq KD cells. Treatment of cells with 1 μM Gӧ 6976, a Ca(2+)-specific PKC inhibitor reduced Ca(2+) mobilization and membrane-associated PKCα and p-PKCα in both cell types. The results indicate that the CaS-mediated increase in [Ca(2+)]i in N18TG2 cells is dependent on Gαi/o proteins via inositol-1,4,5-triphosphate (IP3) channels and store-operated Ca(2+) entry channels, whereas modulation of CaS responses involving PKCα phosphorylation and translocation to the plasma membrane occurs via a Gαq mechanism.
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Affiliation(s)
- John S Sesay
- Cardiovascular Disease Research Program, Julius L Chambers Biomedical/Biotechnology Research Institute, North Carolina Central University, Durham, NC 27707, USA; Department of Biology, North Carolina Central University, Durham, NC 27707, USA; Department of Physiology and Pharmacology and Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA
| | - Reginald N K Gyapong
- Cardiovascular Disease Research Program, Julius L Chambers Biomedical/Biotechnology Research Institute, North Carolina Central University, Durham, NC 27707, USA
| | - Leila T Najafi
- Department of Pharmacological and Physiological Science, Saint Louis University, St. Louis, MO 63104, USA
| | - Sandra L Kabler
- Department of Physiology and Pharmacology and Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA
| | - Debra I Diz
- Department of Physiology and Pharmacology and Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA; Hypertension & Vascular Research Center, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA
| | - Allyn C Howlett
- Department of Biology, North Carolina Central University, Durham, NC 27707, USA; Department of Pharmacological and Physiological Science, Saint Louis University, St. Louis, MO 63104, USA; Department of Physiology and Pharmacology and Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA; Hypertension & Vascular Research Center, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA
| | - Emmanuel M Awumey
- Cardiovascular Disease Research Program, Julius L Chambers Biomedical/Biotechnology Research Institute, North Carolina Central University, Durham, NC 27707, USA; Department of Biology, North Carolina Central University, Durham, NC 27707, USA; Department of Physiology and Pharmacology and Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA; Hypertension & Vascular Research Center, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA.
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Di Mise A, Tamma G, Ranieri M, Svelto M, Heuvel BVD, Levtchenko EN, Valenti G. Conditionally immortalized human proximal tubular epithelial cells isolated from the urine of a healthy subject express functional calcium-sensing receptor. Am J Physiol Renal Physiol 2015; 308:F1200-6. [PMID: 25656364 DOI: 10.1152/ajprenal.00352.2014] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Accepted: 02/03/2015] [Indexed: 02/08/2023] Open
Abstract
The calcium-sensing receptor (CaSR) is a G protein-coupled receptor, which plays an essential role in regulating Ca(2+) homeostasis. Here we show that conditionally immortalized proximal tubular epithelial cell line (ciPTEC) obtained by immortalizing and subcloning cells exfoliated in the urine of a healthy subject expresses functional endogenous CaSR. Immunolocalization studies of polarized ciPTEC revealed the apical localization of the receptor. By Western blotting of ciPTEC lysates, both monomeric and dimeric forms of CaSR at 130 and ∼250 kDa, respectively, were detected. Functional studies indicated that both external calcium and the positive CaSR allosteric modulator, NPS-R568, induced a significant increase in cytosolic calcium, proving a high sensitivity of the endogenous receptor to its agonists. Calcium depletion from the endoplasmic reticulum using cyclopiazonic acid abolished the increase in cytosolic calcium elicited by NPS-R568, confirming calcium exit from intracellular stores. Activation of CaSR by NPS-R significantly reduced the increase in cAMP elicited by forskolin (FK), a direct activator of adenylate cyclase, further confirming the functional expression of the receptor in this cell line. CaSR expressed in ciPTEC was found to interact with Gq as a downstream effector, which in turn can cause release of calcium from intracellular stores via phospholipase C activation. We conclude that human proximal tubular ciPTEC express functional CaSR and respond to its activation with a release of calcium from intracellular stores. These cell lines represent a valuable tool for research into the disorder associated with gain or loss of function of the CaSR by producing cell lines from patients.
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Affiliation(s)
- Annarita Di Mise
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Aldo Moro, Italy
| | - Grazia Tamma
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Aldo Moro, Italy
| | - Marianna Ranieri
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Aldo Moro, Italy
| | - Maria Svelto
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Aldo Moro, Italy; Center of Excellence in Comparative Genomics(CEGBA), Bari, Italy
| | - Bert van den Heuvel
- Department of Pediatric Nephrology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands; and
| | - Elena N Levtchenko
- Department of Pediatric Nephrology, University Hospital Gasthuisberg, Leuven, Belgium
| | - Giovanna Valenti
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Aldo Moro, Italy; Center of Excellence in Comparative Genomics(CEGBA), Bari, Italy;
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Correlation between Choline Peak at MR Spectroscopy and Calcium-Sensing Receptor Expression Level in Breast Cancer: A Preliminary Clinical Study. Mol Imaging Biol 2015; 17:548-56. [DOI: 10.1007/s11307-015-0823-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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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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Mastromatteo E, Lamacchia O, Campo MR, Conserva A, Baorda F, Cinque L, Guarnieri V, Scillitani A, Cignarelli M. A novel mutation in calcium-sensing receptor gene associated to hypercalcemia and hypercalciuria. BMC Endocr Disord 2014; 14:81. [PMID: 25292184 PMCID: PMC4197257 DOI: 10.1186/1472-6823-14-81] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Accepted: 09/29/2014] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Familial Hyperparathyroidism (HPT) and Familial benign Hypocalciuric Hypercalcemia (FHH) are the most common causes of hereditary hypercalcemia. FHH has been demonstrated to be caused by inactivating mutations of calcium-sensing receptor (CaSR) gene, involved in PTH regulation as well as in renal calcium excretion. CASE PRESENTATION In two individuals, father and son, we found a novel heterozygous mutation in CaSR gene. The hypercalcemia was present only in father, which, by contrast to the classic form of FHH showed hypercalciuria (from 300 to 600 mg/24 h in different evaluations) and a Calcium/Creatinine ratio of 0.031, instead of low or normal calciuria (<0.01 typical finding in FHH). His son showed the same mutation in CaSR gene, but no clinical signs or hypercalcemia although serum ionized calcium levels were close to the upper limit of normal values (1.30 mmol/L: normal range: 1.12-1.31 mmol/L). Sequence analysis revealed a point mutation at codon 972 of CaSR gene (chromosome 3q), located within cytoplasmic domain of the CaSR, that changes Threonine with Methionine. The father was treated with Cinacalcet 90 mg/day, with a decrease of total serum calcemia from an average value of 12.2 mg/dl to 10.9 mg/dl. CONCLUSION This is a case of a novel inactivating point mutation of CaSR gene that determines an atypical clinical presentation of FHH, characterized by hypercalcemia, hypercalciuria and inadequate normal PTH levels. Functional assay demonstrated that the 972 M variant influenced the maturation of the protein, in terms of the post-translational glycosylation. The impairment of the receptor activity is in keeping with the specific localization of the 972 residue in the C-terminal tail, assigned to the intracellular signalling, that on the basis of the our findings appears to be differently modulated in parathyroid gland and in kidney.
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Affiliation(s)
- Eugenio Mastromatteo
- />Unit of Endocrinology and Metabolic Diseases, Department of Medical and Surgical Sciences, University of Foggia, Italy, Viale Pinto, 1, 71122 Foggia, Italy
| | - Olga Lamacchia
- />Unit of Endocrinology and Metabolic Diseases, Department of Medical and Surgical Sciences, University of Foggia, Italy, Viale Pinto, 1, 71122 Foggia, Italy
| | - Michela Rosaria Campo
- />Unit of Endocrinology and Metabolic Diseases, Department of Medical and Surgical Sciences, University of Foggia, Italy, Viale Pinto, 1, 71122 Foggia, Italy
| | - Antonella Conserva
- />Unit of Endocrinology and Metabolic Diseases, Department of Medical and Surgical Sciences, University of Foggia, Italy, Viale Pinto, 1, 71122 Foggia, Italy
| | - Filomena Baorda
- />Medical Genetics Service IRCCS “Casa Sollievo della Sofferenza” Hospital viale Padre Pio, 71013 San Giovanni Rotondo, (FG) Italy
| | - Luigia Cinque
- />Medical Genetics Service IRCCS “Casa Sollievo della Sofferenza” Hospital viale Padre Pio, 71013 San Giovanni Rotondo, (FG) Italy
| | - Vito Guarnieri
- />Medical Genetics Service IRCCS “Casa Sollievo della Sofferenza” Hospital viale Padre Pio, 71013 San Giovanni Rotondo, (FG) Italy
| | - Alfredo Scillitani
- />Unit of Endocrinology and Metabolic Diseases IRCCS “Casa Sollievo della Sofferenza” Hospital viale Padre Pio, 71013 San Giovanni Rotondo, (FG) Italy
| | - Mauro Cignarelli
- />Unit of Endocrinology and Metabolic Diseases, Department of Medical and Surgical Sciences, University of Foggia, Italy, Viale Pinto, 1, 71122 Foggia, Italy
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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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González-Vázquez A, Planell JA, Engel E. Extracellular calcium and CaSR drive osteoinduction in mesenchymal stromal cells. Acta Biomater 2014; 10:2824-33. [PMID: 24525034 DOI: 10.1016/j.actbio.2014.02.004] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Revised: 01/10/2014] [Accepted: 02/03/2014] [Indexed: 12/12/2022]
Abstract
Bone is the main store of calcium and progenitor cells in the body. During the resorption process, the local calcium concentration reaches 8-40mM, and the surrounding cells are exposed to these fluctuations in calcium. This stimulus is a signal that is detected through the calcium sensing receptor (CaSR), which modulates chemotactic and proliferative G protein-dependent signaling pathways. The objective of the present work is to evaluate the roles of extracellular calcium ([Ca(2+)]o) and the CaSR in osteoinduction. Rat bone marrow mesenchymal stromal cells (rBMSCs) were stimulated with 10mM of Ca(2+). Several experiments were conducted to demonstrate the effect of [Ca(2+)]o on chemotaxis, proliferation and differentiation on the osteoblastic lineage. It was found that [Ca(2+)]o induces rBMSCs to migrate and proliferate in a concentration-dependent manner. Real-time polymerase chain reaction and immunofluorescence also revealed that 10mM Ca(2+) stimulates overexpression of osteogenic markers in rBMSCs, including alkaline phosphatase (ALP), bone sialoprotein, collagen Ia1 and osteocalcin. Functional assays determining ALP activity and mineralization tests both corroborate the increased expression of these markers in rBMSCs stimulated with Ca(2+). Moreover, CaSR blockage inhibited the cellular response to stimulation with high concentrations of [Ca(2+)]o, revealing that the CaSR is a key modulator of these cellular responses.
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Affiliation(s)
- Arlyng González-Vázquez
- Biomaterials for Regenerative Therapies Group, Institute for Bioengineering of Catalonia, Baldiri Reixac 15-21, Barcelona 08028, Spain; CIBER-BBN, María de Luna 11, Zaragoza 50118, Spain
| | - Josep A Planell
- Biomaterials for Regenerative Therapies Group, Institute for Bioengineering of Catalonia, Baldiri Reixac 15-21, Barcelona 08028, Spain; CIBER-BBN, María de Luna 11, Zaragoza 50118, Spain
| | - Elisabeth Engel
- Biomaterials for Regenerative Therapies Group, Institute for Bioengineering of Catalonia, Baldiri Reixac 15-21, Barcelona 08028, Spain; Technical University of Catalonia, Av. Diagonal 647, Barcelona 08028, Spain; CIBER-BBN, María de Luna 11, Zaragoza 50118, Spain.
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Zhang K, Wang P, Huang S, Wang X, Li T, Jin Y, Hehir M, Xu C. Different mechanism of LPS-induced calcium increase in human lung epithelial cell and microvascular endothelial cell: a cell culture study in a model for ARDS. Mol Biol Rep 2014; 41:4253-9. [PMID: 24584519 DOI: 10.1007/s11033-014-3296-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2013] [Accepted: 02/13/2014] [Indexed: 01/11/2023]
Abstract
Acute respiratory distress syndrome (ARDS) is a contemporary term incorporating the historic 'acute lung injury' and the colloquial term 'shock lung'. ARDS remains a serious and enigmatic human disease, causing significant mortality. The mechanisms involved at the alveolar cell/capillary endothelial interface have been explored but to date we lack clarity on the role of intracellular calcium ([Ca(2+)]i) fluxes across this interface. To explore the mechanisms of Ca(2+) induced inflammatory reaction in epithelial cells and pulmonary microvascular endothelial cells (HMVEC) located at the two sides of blood-air barrier, lung epithelial A549 and HMVEC cells were treated with LPS. Our results demonstrated that LPS evoked the increase of [Ca(2+)]i, TNF-α and IL-8 in both cells types. The [Ca(2+)]i increases involved intracellular but not extracellular Ca(2+) sources in A549, but both intracellular and extracellular Ca(2+) sources in HMVEC cells. The effects of LPS on both cells types were completely inhibited by the combination of LPS and CaSR-targeted siRNA. Furthermore, LPS-inhibited cell proliferations were significantly reversed by the combined treatment. Therefore, LPS induced different mechanisms of [Ca(2+)]i increase during the activation of CaSR in A549 and HMVEC cells, which translates into functional outputs related to ARDS.
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Affiliation(s)
- Kejing Zhang
- Ningbo Medical Center, LiHuiLi Hospital, Medical School, Ningbo University, Ningbo, 315041, China
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Casare F, Milan D, Fernandez R. Stimulation of calcium-sensing receptor increases biochemical H⁺-ATPase activity in mouse cortex and outer medullary regions. Can J Physiol Pharmacol 2013; 92:181-8. [PMID: 24593782 DOI: 10.1139/cjpp-2013-0256] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The aim of this project was to investigate the interaction between the calcium-sensing receptor (CaSR) and proton extrusion by the V-ATPase and gastric-like isoform of the H(+)/K(+)-ATPase in the mouse nephron. Biochemical activity of H(+)- ATPases was analysed using a partially purified membrane fraction of mouse cortex and outer medullary region. The V-ATPase activity (sensitive to 10(-7) mol·L(-1) bafilomycin) from the cortical and outer medullary region was significantly stimulated by increasing the [Formula: see text] (outside Ca(2+)), in a dose-dependent pattern. Gastric H(+)/K(+)-ATPase activity (sensitive to 10(-5) mol·L(-1) Schering 28080) was also sensitive to changes in [Formula: see text] levels. A significant increase in V-ATPase activity was also observed when CaSR was stimulated with agonists such as 300 μmol·L(-1) Gd(3+) and 200 μmol·L(-1) neomycin, both in the cortex and outer medulla. The cortical and outer medullary gastric H(+)/K(+)-ATPase activity was also stimulated by Gd(3+) and neomycin. Finally, cortical V-ATPase activity was significantly stimulated by 10(-9) mol·L(-1) angiotensin II, and the stimulation of CaSR in the presence of angiotensin significantly enhanced this effect, suggesting that an interaction in the intracellular signaling pathways is involved. In summary, CaSR stimulation enhances the biochemical activity of V-ATPase and gastric H(+)/K(+)-ATPase in both the cortical and outer medullary region of mouse kidney.
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Affiliation(s)
- Fernando Casare
- Departamento de Fisiologia, Setor de Ciências Biológicas, Universidade Federal do Paraná (UFPR), Centro Politécnico s/n., PO Box 19031, Jardim das Américas, Curitiba, Paraná, CEP 81531-990, Brasil
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Hendy GN, Canaff L, Cole DEC. The CASR gene: alternative splicing and transcriptional control, and calcium-sensing receptor (CaSR) protein: structure and ligand binding sites. Best Pract Res Clin Endocrinol Metab 2013; 27:285-301. [PMID: 23856260 DOI: 10.1016/j.beem.2013.02.009] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The calcium-sensing receptor (CaSR) is a G protein-coupled receptor encoded by a single copy gene. The human CASR gene spans ~103-kb and has eight exons. Promoters P1 and P2 drive transcription of exons 1A and 1B, respectively, encoding alternative 5'-UTRs that splice to exon 2 encoding the common part of the 5'-UTR. Exons 2-7 encode the CaSR protein of 1078 amino acids. Functional elements responsive to 1,25-dihydroxyvitamin D, proinflammatory cytokines, and glial cells missing-2 are present in the CASR promoters. Evolutionarily, the exon structure, first seen in aquatic vertebrates, is well-conserved with a single linkage disequilibrium haplotype block for protein coding exons 2-7. Structural features of the human CaSR protein are: an N-terminal signal peptide (19 amino acids (aa)); an extracellular domain (~600 aa) having a bi-lobed Venus Flytrap (VFT) domain with several Ca(2+)-binding sites; and a nine-cysteines domain that transduces the activation signal to the 7-transmembrane domain (250 aa) and the C-terminal tail (216 aa).
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Affiliation(s)
- Geoffrey N Hendy
- Calcium Research Laboratory, and Hormones and Cancer Research Unit, Royal Victoria Hospital and McGill University Health Centre, Montreal, QC H3A 1A1, Canada.
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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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Park SY, Mun HC, Eom YS, Baek HL, Jung TS, Kim CH, Hong S, Lee S. Identification and characterization of D410E, a novel mutation in the loop 3 domain of CASR, in autosomal dominant hypocalcemia and a therapeutic approach using a novel calcilytic, AXT914. Clin Endocrinol (Oxf) 2013; 78:687-93. [PMID: 23009664 DOI: 10.1111/cen.12056] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Revised: 08/06/2012] [Accepted: 09/19/2012] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Activating mutations of the calcium-sensing receptor (CASR) gene are associated with autosomal dominant hypocalcemia (ADH) characterized by benign hypocalcemia, inappropriately low (PTH) levels and mostly hypercalciuria. Herein, we report a novel activating mutation in the CASR gene in a Korean family with ADH. METHOD The CASR gene was sequenced in the patient with ADH. The identified mutations were also evaluated in the patient's family members by PCR-based sequencing. For functional studies, we examined phosphorylation of ERK1/2. In addition, intracellular Ca(2+) mobilization and the effects of the calcilytic, AXT914 were measured using fluorophore Fura-2 dye. RESULT Direct sequencing analysis of the CASR gene showed that the proband and her daughter possess a novel mutation c.1230T>A, resulting in a D410E missense mutation on exon 4 of the CASR gene. Escalation of the extracellular Ca(2+) concentration resulted in stronger phosphorylation of ERK1/2 and higher levels of intracellular Ca(2+) in HEK293 cells expressing mutant CASR, compared with wild-type CASR. The increase in intracellular Ca(2+) signalling via CASR was successively blunted by treatment with AXT914. CONCLUSIONS Over 60 activating mutations in the CASR gene have been identified to cause ADH so far. Here, we add one more activating mutation that causes ADH. The novel activating mutation (D410E) occurred in the loop 3 region of CASR, where its function was believed to be of little importance; therefore, this mutation may be of interest. Further clinical study will be needed to validate the effectiveness of calcilytics in treatment of ADH in vivo.
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Affiliation(s)
- So Young Park
- Department of Internal Medicine, Cheil General Hospital, Kwandong University College of Medicine, Seoul, Korea
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García Soblechero E, Ferrer Castillo MT, Jiménez Crespo B, Domínguez Quintero ML, González Fuentes C. Neonatal hypercalcemia due to a homozygous mutation in the calcium-sensing receptor: failure of cinacalcet. Neonatology 2013; 104:104-8. [PMID: 23817301 DOI: 10.1159/000350540] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Accepted: 03/01/2013] [Indexed: 11/19/2022]
Abstract
A neonate affected by a novel inactivating mutation in the calcium-sensing receptor (CASR) gene is presented. This mutation is homozygously inherited and has not been previously described. A deletion in exon 5 (c.1392_1404del13) of the gene causes a loss of function of the receptor, which results in neonatal severe hyperparathyroidism and an ensuing extreme hypercalcemia. In a case of homozygosis of the CASR gene, the use of cinacalcet is the second reported calcimimetic treatment attempt and the first treatment attempt prior to surgery. However, because of the type of mutation, parathyroid surgery was necessary at 4 months of age after therapeutic failure. Because there are multiple mutations that affect the CASR gene in different ways, treatment with cinacalcet as an alternative to surgery may be valuable in homozygous cases that are caused by different mutations than the reported case.
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Tonack S, Tang C, Offermanns S. Endogenous metabolites as ligands for G protein-coupled receptors modulating risk factors for metabolic and cardiovascular disease. Am J Physiol Heart Circ Physiol 2012; 304:H501-13. [PMID: 23241321 DOI: 10.1152/ajpheart.00641.2012] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
During the last decade, several G protein-coupled receptors activated by endogenous metabolites have been described. These receptors respond to fatty acids, mono- and disaccharides, amino acids, or various intermediates and products of metabolism, including ketone bodies, lactate, succinate, or bile acids. Receptors of endogenous metabolites are expressed in taste cells, the gastrointestinal tract, adipose tissue, endocrine glands, immune cells, or the kidney and are therefore in a position to sense food intake in the gastrointestinal tract or to link metabolite levels to the appropriate responses of metabolic organs. Some of the receptors appear to provide a link between metabolic and neuronal or immune functions. Given that many of these metabolic processes are dysregulated under pathological conditions, including diabetes, dyslipidemia, and obesity, receptors of endogenous metabolites have also been recognized as potential drug targets to prevent and/or treat metabolic and cardiovascular diseases. This review describes G protein-coupled receptors activated by endogenous metabolites and summarizes their physiological, pathophysiological, and potential pharmacological roles.
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Affiliation(s)
- Sarah Tonack
- Department of Pharmacology, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany
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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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Improvement of ginsenoside Rg1 on hematopoietic function in cyclophosphamide-induced myelosuppression mice. Eur J Pharmacol 2012; 695:7-12. [PMID: 22940261 DOI: 10.1016/j.ejphar.2012.07.050] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Revised: 07/23/2012] [Accepted: 07/30/2012] [Indexed: 12/24/2022]
Abstract
This study was aimed to investigate the effects of ginsenoside Rg1 (Rg1) on hematopoietic function of bone marrow in cyclophosphamide-induced bone marrow depression mice. Mice were given cyclophosphamide (150mg/kg, i.p. for three days) to produce bone marrow depression. Rg1 was then administrated at 7.5 and 15mg/kg by i.p. for seven days. Bone marrow cells number was counted, and the percentage of hematopoietic stem cells (Lin(-)Sca-1(+)c-kit(+)) was quantified by flow cytometry. The histology of femoral bone was examined by H&E staining. The expression of calcium-sensing receptor mRNA was determined by the real time RT-PCR. Rg1 (7.5 and 15mg/kg) protected against cyclophosphamide-induced bone marrow depression, as evidenced by increased bone marrow cell numbers and improved femoral bone morphology. The percentage of Lin(-)Sca-1(+)c-kit(+) cells and lymphoid lineage CD3(+) cells were lower in cyclophosphamide group, but returned towards normal after Rg1 treatment in both bone marrow and peripheral blood cells. Expression of calcium-sensing receptor mRNA was increased in bone marrow cells on the 10th day after cyclophosphamide, but it was returned to normal level after Rg1 treatment. Rg1 alone did not produce these changes in normal mice. These results demonstrated that Rg1 improved hematopoietic function of bone marrow in cyclophosphamide-induced myelosuppression.
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Macedo-Junior SJ, Nascimento FP, Luiz-Cerutti M, Santos ARS. Role of pertussis toxin-sensitive G-protein, K+ channels, and voltage-gated Ca2+ channels in the antinociceptive effect of inosine. Purinergic Signal 2012; 9:51-8. [PMID: 22806273 DOI: 10.1007/s11302-012-9327-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Accepted: 06/26/2012] [Indexed: 12/20/2022] Open
Abstract
Inosine is the first metabolite of adenosine. It exerts an antinociceptive effect by activating the adenosine A(1) and A(2A) receptors. We have previously demonstrated that inosine exhibits antinociceptive properties in acute and chronic mice models of nociception. The aim of this study was to investigate the involvement of pertussis toxin-sensitive G-protein-coupled receptors, as well as K(+) and Ca(2+) channels, in the antinociception promoted by inosine in the formalin test. Mice were pretreated with pertussis toxin (2.5 μg/site, i.t., an inactivator of G(i/0) protein); after 7 days, they received inosine (10 mg/kg, i.p.) or morphine (2.5 mg/kg, s.c., used as positive control) immediately before the formalin test. Another group of animals received tetraethylammonium (TEA) or 4-aminopyridine (4-AP) (1 μg/site, i.t., a non-specific voltage-gated K(+) channel blockers), apamin (50 ng/site, i.t., a small conductance Ca(2+)-activated K(+) channel blocker), charybdotoxin (250 pg/site, i.t., a large-conductance Ca(2+)-activated K(+) channel blocker), glibenclamide (100 μg/site, i.t., an ATP-sensitive K(+) channel blocker) or CaCl(2) (200 nmol/site, i.t.). Afterwards, the mice received inosine (10 mg/kg, i.p.), diclofenac (10 mg/kg, i.p., a positive control), or morphine (2.5 mg/kg, s.c., a positive control) immediately before the formalin test. The antinociceptive effect of inosine was reversed by the pre-administration of pertussis toxin (2.5 μg/site, i.t.), TEA, 4-aminopyridine, charybdotoxin, glibenclamide, and CaCl(2), but not apamin. Further, all K(+) channel blockers and CaCl(2) reversed the antinociception induced by diclofenac and morphine, respectively. Taken together, these data suggest that the antinociceptive effect of inosine is mediated, in part, by pertussis toxin-sensitive G-protein coupled receptors and the subsequent activation of voltage gated K(+) channel, large conductance Ca(2+)-activated and ATP-sensitive K(+) channels or inactivation of voltage-gated Ca(2+) channels. Finally, small conductance Ca(2+)-activated K(+) channels are not involved in the antinociceptive effect of inosine.
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Affiliation(s)
- Sérgio José Macedo-Junior
- Laboratório de Neurobiologia da Dor e Inflamação, Departamento de Ciências Fisiológicas, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Campus Trindade, Florianópolis, SC, 88040-900, Brazil
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Yamamura A, Guo Q, Yamamura H, Zimnicka AM, Pohl NM, Smith KA, Fernandez RA, Zeifman A, Makino A, Dong H, Yuan JXJ. Enhanced Ca(2+)-sensing receptor function in idiopathic pulmonary arterial hypertension. Circ Res 2012; 111:469-81. [PMID: 22730443 DOI: 10.1161/circresaha.112.266361] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
RATIONALE A rise in cytosolic Ca(2+) concentration ([Ca(2+)](cyt)) in pulmonary arterial smooth muscle cells (PASMC) is an important stimulus for pulmonary vasoconstriction and vascular remodeling. Increased resting [Ca(2+)](cyt) and enhanced Ca(2+) influx have been implicated in PASMC from patients with idiopathic pulmonary arterial hypertension (IPAH). OBJECTIVE We examined whether the extracellular Ca(2+)-sensing receptor (CaSR) is involved in the enhanced Ca(2+) influx and proliferation in IPAH-PASMC and whether blockade of CaSR inhibits experimental pulmonary hypertension. METHODS AND RESULTS In normal PASMC superfused with Ca(2+)-free solution, addition of 2.2 mmol/L Ca(2+) to the perfusate had little effect on [Ca(2+)](cyt). In IPAH-PASMC, however, restoration of extracellular Ca(2+) induced a significant increase in [Ca(2+)](cyt). Extracellular application of spermine also markedly raised [Ca(2+)](cyt) in IPAH-PASMC but not in normal PASMC. The calcimimetic R568 enhanced, whereas the calcilytic NPS 2143 attenuated, the extracellular Ca(2+)-induced [Ca(2+)](cyt) rise in IPAH-PASMC. Furthermore, the protein expression level of CaSR in IPAH-PASMC was greater than in normal PASMC; knockdown of CaSR in IPAH-PASMC with siRNA attenuated the extracellular Ca(2+)-mediated [Ca(2+)](cyt) increase and inhibited IPAH-PASMC proliferation. Using animal models of pulmonary hypertension, our data showed that CaSR expression and function were both enhanced in PASMC, whereas intraperitoneal injection of the calcilytic NPS 2143 prevented the development of pulmonary hypertension and right ventricular hypertrophy in rats injected with monocrotaline and mice exposed to hypoxia. CONCLUSIONS The extracellular Ca(2+)-induced increase in [Ca(2+)](cyt) due to upregulated CaSR is a novel pathogenic mechanism contributing to the augmented Ca(2+) influx and excessive PASMC proliferation in patients and animals with pulmonary arterial hypertension.
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Affiliation(s)
- Aya Yamamura
- Kinjo Gakuin University School of Pharmacy, Nagoya, Japan
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Haid DC, Jordan-Biegger C, Widmayer P, Breer H. Receptors responsive to protein breakdown products in g-cells and d-cells of mouse, swine and human. Front Physiol 2012; 3:65. [PMID: 22514536 PMCID: PMC3322525 DOI: 10.3389/fphys.2012.00065] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Accepted: 03/05/2012] [Indexed: 11/13/2022] Open
Abstract
Monitoring the luminal content in the stomach is of vital importance for adjusting the gastric activities, including the release of gastric hormones such as gastrin. Our previous studies have shown that in mice the gastrin-secreting G-cells express receptor types which are responsive to amino acids. Since the pig is considered as more suitable model for studying gastro-physiological aspects relevant for men, in this study we have analyzed the distribution of G-cells and D-cells in the gastric antrum of men, swine, and mouse and the expression of receptor types which may render these cells responsiveness to protein breakdown products. The results indicate that the number of G-cells per antral invagination was significantly higher in swine and human compared to mice and also the distribution pattern of G-cells differed between the species. The molecular phenotyping revealed that the receptors GPRC6A and CaSR were also expressed in G-cells and in a subpopulation of D-cells from swine and men. As an additional receptor type, the peptone-receptor GPR92, was found to be expressed in G-cells and a subpopulation of D-cells; this receptor type may be particular suitable for sensing protein breakdown products and thus be a key element to adjust the activity of G-cells and D-cells according to the progress of the digestive processes in the stomach. In search for elements of an intracellular signaling cascade it was found that G-cells express the G-protein subunit Gαq as well as the phospholipase C subtype PLCβ3; in contrast, D-cells expressed the subtype PLCβ2 and neither Gαq. These results indicate that there are significant species differences concerning the number and distribution pattern, but not concerning the molecular phenotype of the gastric endocrine cells. However, G-cells and D-cells significantly differ from each other regarding the repertoire of receptors and signaling elements.
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The role of the calcium-sensing receptor in human disease. Clin Biochem 2012; 45:943-53. [PMID: 22503956 DOI: 10.1016/j.clinbiochem.2012.03.034] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Revised: 03/22/2012] [Accepted: 03/27/2012] [Indexed: 01/18/2023]
Abstract
Following the discovery of the calcium-sensing receptor (CaSR) in 1993, its pivotal role in disorders of calcium homeostasis such as Familial Hypocalciuric Hypercalcemia (FHH) was quickly demonstrated. Since then, it has become clear that the CaSR has immense functional versatility largely through its ability to activate many different signaling pathways in a ligand- and tissue-specific manner. This allows the receptor to play diverse and crucial roles in human physiology and pathophysiology, both in calcium homeostasis and in tissues and biological processes unrelated to calcium balance. This review covers current knowledge of the role of the CaSR in disorders of calcium homeostasis (FHH, neonatal severe hyperparathyroidism, autosomal dominant hypocalcemia, primary and secondary hyperparathyroidism, hypercalcemia of malignancy) as well as unrelated diseases such as breast and colorectal cancer (where the receptor appears to play a tumor suppressor role), Alzheimer's disease, pancreatitis, diabetes mellitus, hypertension and bone and gastrointestinal disorders. In addition, it examines the use or potential use of CaSR agonists or antagonists (calcimimetics and calcilytics) and other drugs mediated through the CaSR, in the management of disorders as diverse as hyperparathyroidism, osteoporosis and gastrointestinal disease.
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Lusche DF, Wessels D, Scherer A, Daniels K, Kuhl S, Soll DR. The IplA Ca2+ channel of Dictyostelium discoideum is necessary for chemotaxis mediated through Ca2+, but not through cAMP, and has a fundamental role in natural aggregation. J Cell Sci 2012; 125:1770-83. [PMID: 22375061 DOI: 10.1242/jcs.098301] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
During aggregation of Dictyostelium discoideum, nondissipating, symmetrical, outwardly moving waves of cAMP direct cells towards aggregation centers. It has been assumed that the spatial and temporal characteristics of the front and back of each cAMP wave regulate both chemokinesis and chemotaxis. However, during the period preceding aggregation, cells acquire not only the capacity to chemotax in a spatial gradient of cAMP, but also in a spatial gradient of Ca(2+). The null mutant of the putative IplA Ca(2+) channel gene, iplA(-), undergoes normal chemotaxis in spatial gradients of cAMP and normal chemokinetic responses to increasing temporal gradients of cAMP, both generated in vitro. However, iplA(-) cells lose the capacity to undergo chemotaxis in response to a spatial gradient of Ca(2+), suggesting that IplA is either the Ca(2+) chemotaxis receptor or an essential component of the Ca(2+) chemotaxis regulatory pathway. In response to natural chemotactic waves generated by wild-type cells, the chemokinetic response of iplA(-) cells to the temporal dynamics of the cAMP wave is intact, but the capacity to reorient in the direction of the aggregation center at the onset of each wave is lost. These results suggest that transient Ca(2+) gradients formed between cells at the onset of each natural cAMP wave augment reorientation towards the aggregation center. If this hypothesis proves correct, it will provide a more complex contextual framework for interpreting D. discoideum chemotaxis.
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Affiliation(s)
- Daniel F Lusche
- W M Keck Dynamic Image Analysis Facility, Department of Biology, University of Iowa, Iowa City, IA 52242, USA
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The adaptor protein 14-3-3 binds to the calcium-sensing receptor and attenuates receptor-mediated Rho kinase signalling. Biochem J 2012; 441:995-1006. [DOI: 10.1042/bj20111277] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
A yeast two-hybrid screen performed to identify binding partners of the CaR (calcium-sensing receptor) intracellular tail identified the adaptor protein 14-3-3θ as a novel binding partner that bound to the proximal membrane region important for CaR expression and signalling. The 14-3-3θ protein directly interacted with the CaR tail in pull-down studies and FLAG-tagged CaR co-immunoprecipitated with EGFP (enhanced green fluorescent protein)-tagged 14-3-3θ when co-expressed in HEK (human embryonic kidney)-293 or COS-1 cells. The interaction between the CaR and 14-3-3θ did not require a putative binding site in the membrane-proximal region of the CaR tail and was independent of PKC (protein kinase C) phosphorylation. Confocal microscopy demonstrated co-localization of the CaR and EGFP–14-3-3θ in the ER (endoplasmic reticulum) of HEK-293 cells that stably expressed the CaR (HEK-293/CaR cells), but 14-3-3θ overexpression had no effect on membrane expression of the CaR. Overexpression of 14-3-3θ in HEK-293/CaR cells attenuated CaR-mediated Rho signalling, but had no effect on ERK (extracellular-signal-regulated kinase) 1/2 signalling. Another isoform identified from the library, 14-3-3ζ, exhibited similar behaviour to that of 14-3-3θ with respect to CaR tail binding, cellular co-localization and impact on receptor-mediated signalling. However, unlike 14-3-3θ, this isoform, when overexpressed, significantly reduced CaR plasma membrane expression. Results indicate that 14-3-3 proteins mediate CaR-dependent Rho signalling and may modulate the plasma membrane expression of the CaR.
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Anti-allodynic effect of the flavonoid myricetin in a rat model of neuropathic pain: Involvement of p38 and protein kinase C mediated modulation of Ca2+
channels. Eur J Pain 2012; 14:992-8. [DOI: 10.1016/j.ejpain.2010.04.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2009] [Revised: 03/18/2010] [Accepted: 04/14/2010] [Indexed: 02/04/2023]
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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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Micaroni M. Calcium around the Golgi apparatus: implications for intracellular membrane trafficking. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 740:439-60. [PMID: 22453953 DOI: 10.1007/978-94-007-2888-2_18] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
As with other complex cellular functions, intracellular membrane transport involves the coordinated engagement of a series of organelles and machineries; in the last couple of decades more importance has been given to the role of calcium (Ca(2+)) in the regulation of membrane trafficking, which is directly involved in coordinating the endoplasmic reticulum-to-Golgi-to-plasma membrane delivery of cargo. Consequently, the Golgi apparatus (GA) is now considered not just the place proteins mature in as they move to their final destination(s), but it is increasingly viewed as an intracellular Ca(2+) store. In the last few years the mechanisms regulating the homeostasis of Ca(2+) in the GA and its role in membrane trafficking have begun to be elucidated. Here, these recent discoveries that shed light on the role Ca(2+) plays as of trigger of different steps during membrane trafficking has been reviewed. This includes recruitment of proteins and SNARE cofactors to the Golgi membranes, which are both fundamental for the membrane remodeling and the regulation of fusion/fission events occurring during the passage of cargo across the GA. I conclude by focusing attention on Ca(2+) homeostasis dysfunctions in the GA and their related pathological implications.
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Affiliation(s)
- Massimo Micaroni
- Division of Molecular Cell Biology, Institute for Molecular Bioscience, The University of Queensland, 306 Carmody Road, 4072 Brisbane, St. Lucia, QLD, Australia.
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