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Thompson MD, Percy ME, Cole DEC, Bichet DG, Hauser AS, Gorvin CM. G protein-coupled receptor (GPCR) gene variants and human genetic disease. Crit Rev Clin Lab Sci 2024; 61:317-346. [PMID: 38497103 DOI: 10.1080/10408363.2023.2286606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 08/28/2023] [Accepted: 11/19/2023] [Indexed: 03/19/2024]
Abstract
Genetic variations in the genes encoding G protein-coupled receptors (GPCRs) can disrupt receptor structure and function, which can result in human genetic diseases. Disease-causing mutations have been reported in at least 55 GPCRs for more than 66 monogenic diseases in humans. The spectrum of pathogenic and likely pathogenic variants includes loss of function variants that decrease receptor signaling on one extreme and gain of function that may result in biased signaling or constitutive activity, originally modeled on prototypical rhodopsin GPCR variants identified in retinitis pigmentosa, on the other. GPCR variants disrupt ligand binding, G protein coupling, accessory protein function, receptor desensitization and receptor recycling. Next generation sequencing has made it possible to identify variants of uncertain significance (VUS). We discuss variants in receptors known to result in disease and in silico strategies for disambiguation of VUS such as sorting intolerant from tolerant and polymorphism phenotyping. Modeling of variants has contributed to drug development and precision medicine, including drugs that target the melanocortin receptor in obesity and interventions that reverse loss of gonadotropin-releasing hormone receptor from the cell surface in idiopathic hypogonadotropic hypogonadism. Activating and inactivating variants of the calcium sensing receptor (CaSR) gene that are pathogenic in familial hypocalciuric hypercalcemia and autosomal dominant hypocalcemia have enabled the development of calcimimetics and calcilytics. Next generation sequencing has continued to identify variants in GPCR genes, including orphan receptors, that contribute to human phenotypes and may have therapeutic potential. Variants of the CaSR gene, some encoding an arginine-rich region that promotes receptor phosphorylation and intracellular retention, have been linked to an idiopathic epilepsy syndrome. Agnostic strategies have identified variants of the pyroglutamylated RF amide peptide receptor gene in intellectual disability and G protein-coupled receptor 39 identified in psoriatic arthropathy. Coding variants of the G protein-coupled receptor L1 (GPR37L1) orphan receptor gene have been identified in a rare familial progressive myoclonus epilepsy. The study of the role of GPCR variants in monogenic, Mendelian phenotypes has provided the basis of modeling the significance of more common variants of pharmacogenetic significance.
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Affiliation(s)
- Miles D Thompson
- Krembil Brain Institute, Toronto Western Hospital, Toronto, ON, Canada
| | - Maire E Percy
- Departments of Physiology and Obstetrics & Gynaecology, University of Toronto, Toronto, ON, Canada
| | - David E C Cole
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
| | - Daniel G Bichet
- Department of Physiology and Medicine, Hôpital du Sacré-Coeur, Université de Montréal, QC, Canada
| | - Alexander S Hauser
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Caroline M Gorvin
- Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Birmingham, West Midlands, UK
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Venneri M, Vezzi V, Di Mise A, Ranieri M, Centrone M, Tamma G, Nejsum LN, Valenti G. Novel signalling pathways in nephrogenic syndrome of inappropriate antidiuresis: functional implication of site-specific AQP2 phosphorylation. J Physiol 2024; 602:3169-3189. [PMID: 36823952 DOI: 10.1113/jp284039] [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: 11/18/2022] [Accepted: 02/10/2023] [Indexed: 02/25/2023] Open
Abstract
Nephrogenic syndrome of inappropriate antidiuresis (NSIAD) is a rare X-linked disease caused by gain-of-function mutations of arginine vasopressin receptor 2 (V2R). Patients with NSIAD are characterized by the inability to excrete a free water load and by inappropriately increased urinary osmolality despite very low levels of plasma vasopressin, resulting in euvolaemic hyponatraemia. To dissect the signalling downstream V2R constitutively active variants, Flp-In T-REx Madin-Darby canine kidney (FTM) cells, stably transfected with V2R mutants (R137L, R137C and F229V) and AQP2-wt or non-phosphorylatable AQP2-S269A/AQP2-S256A, were used as cellular models. All three activating V2R mutations presented constitutive plasma membrane expression of AQP2-wt and significantly higher basal water permeability. In addition, V2R-R137L/C showed significantly higher activity of Rho-associated kinase (ROCK), a serine/threonine kinase previously suggested to be involved in S269-AQP2 phosphorylation downstream of these V2R mutants. Interestingly, FTM cells expressing V2R-R137L/C mutants and AQP2-S269A showed a significant reduction in AQP2 membrane abundance and a significant reduction in ROCK activity, indicating the crucial importance of S269-AQP2 phosphorylation in the gain-of-function phenotype. Conversely, V2R-R137L/C mutants retained the gain-of-function phenotype when AQP2-S256A was co-expressed. In contrast, cells expressing the F229V mutant and the non-phosphorylatable AQP2-S256A had a significant reduction in AQP2 membrane abundance along with a significant reduction in basal osmotic water permeability, indicating a crucial role of Ser256 for this mutant. These data indicate that the constitutive AQP2 trafficking associated with the gain-of-function V2R-R137L/C mutants causing NSIAD is protein kinase A independent and requires an intact Ser269 in AQP2 under the control of ROCK phosphorylation. KEY POINTS: Nephrogenic syndrome of inappropriate antidiuresis is caused by two constitutively active variant phenotypes of AVPR2, one sensitive to vaptans (V2R-F229V) and the other vaptan resistant (V2R-R137C/L). In renal cells, all three activating arginine vasopressin receptor 2 (V2R) variants display constitutive AQP2 plasma membrane expression and high basal water permeability. In cells expressing V2R-R137L/C mutants, disruption of the AQP2-S269 phosphorylation site caused the loss of the gain-of-function phenotype, which, in contrast, was retained in V2R-F229V-expressing cells. Cells expressing the V2R-F229V mutant were instead sensitive to disruption of the AQP2-S256 phosphorylation site. The serine/threonine kinase Rho-associated kinase (ROCK) was found to be involved in AQP2-S269 phosphorylation downstream of the V2R-R137L/C mutants. These findings might have clinical relevance for patients with nephrogenic syndrome of inappropriate antidiuresis.
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Affiliation(s)
- Maria Venneri
- Department of Biosciences, Biotechnology and Environment, University of Bari Aldo Moro, Bari, Italy
| | - Vanessa Vezzi
- National Center for Drug Research and Evaluation, Istituto Superiore di Sanità, Rome, Italy
| | - Annarita Di Mise
- Department of Biosciences, Biotechnology and Environment, University of Bari Aldo Moro, Bari, Italy
| | - Marianna Ranieri
- Department of Biosciences, Biotechnology and Environment, University of Bari Aldo Moro, Bari, Italy
| | - Mariangela Centrone
- Department of Biosciences, Biotechnology and Environment, University of Bari Aldo Moro, Bari, Italy
| | - Grazia Tamma
- Department of Biosciences, Biotechnology and Environment, University of Bari Aldo Moro, Bari, Italy
| | - Lene N Nejsum
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Giovanna Valenti
- Department of Biosciences, Biotechnology and Environment, University of Bari Aldo Moro, Bari, Italy
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Duan J, He XH, Li SJ, Xu HE. Cryo-electron microscopy for GPCR research and drug discovery in endocrinology and metabolism. Nat Rev Endocrinol 2024; 20:349-365. [PMID: 38424377 DOI: 10.1038/s41574-024-00957-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 01/29/2024] [Indexed: 03/02/2024]
Abstract
G protein-coupled receptors (GPCRs) are the largest family of cell surface receptors, with many GPCRs having crucial roles in endocrinology and metabolism. Cryogenic electron microscopy (cryo-EM) has revolutionized the field of structural biology, particularly regarding GPCRs, over the past decade. Since the first pair of GPCR structures resolved by cryo-EM were published in 2017, the number of GPCR structures resolved by cryo-EM has surpassed the number resolved by X-ray crystallography by 30%, reaching >650, and the number has doubled every ~0.63 years for the past 6 years. At this pace, it is predicted that the structure of 90% of all human GPCRs will be completed within the next 5-7 years. This Review highlights the general structural features and principles that guide GPCR ligand recognition, receptor activation, G protein coupling, arrestin recruitment and regulation by GPCR kinases. The Review also highlights the diversity of GPCR allosteric binding sites and how allosteric ligands could dictate biased signalling that is selective for a G protein pathway or an arrestin pathway. Finally, the authors use the examples of glycoprotein hormone receptors and glucagon-like peptide 1 receptor to illustrate the effect of cryo-EM on understanding GPCR biology in endocrinology and metabolism, as well as on GPCR-related endocrine diseases and drug discovery.
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Affiliation(s)
- Jia Duan
- Zhongshan Institute for Drug Discovery, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Zhongshan, China.
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.
- University of Chinese Academy of Sciences, Beijing, China.
| | - Xin-Heng He
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Shu-Jie Li
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
- Department of Traditional Chinese Medicine, Fujian Medical University Union Hospital, Fuzhou, Fujian, China
| | - H Eric Xu
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.
- University of Chinese Academy of Sciences, Beijing, China.
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China.
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Daly C, Guseinov AA, Hahn H, Wright A, Tikhonova IG, Thomsen ARB, Plouffe B. β-Arrestin-dependent and -independent endosomal G protein activation by the vasopressin type 2 receptor. eLife 2023; 12:RP87754. [PMID: 37855711 PMCID: PMC10586804 DOI: 10.7554/elife.87754] [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] [Indexed: 10/20/2023] Open
Abstract
The vasopressin type 2 receptor (V2R) is an essential G protein-coupled receptor (GPCR) in renal regulation of water homeostasis. Upon stimulation, the V2R activates Gαs and Gαq/11, which is followed by robust recruitment of β-arrestins and receptor internalization into endosomes. Unlike canonical GPCR signaling, the β-arrestin association with the V2R does not terminate Gαs activation, and thus, Gαs-mediated signaling is sustained while the receptor is internalized. Here, we demonstrate that this V2R ability to co-interact with G protein/β-arrestin and promote endosomal G protein signaling is not restricted to Gαs, but also involves Gαq/11. Furthermore, our data imply that β-arrestins potentiate Gαs/Gαq/11 activation at endosomes rather than terminating their signaling. Surprisingly, we found that the V2R internalizes and promote endosomal G protein activation independent of β-arrestins to a minor degree. These new observations challenge the current model of endosomal GPCR signaling and suggest that this event can occur in both β-arrestin-dependent and -independent manners.
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Affiliation(s)
- Carole Daly
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen’s University BelfastBelfastUnited Kingdom
| | | | - Hyunggu Hahn
- Department of Molecular Pathobiology, New York University College of DentistryNew YorkUnited States
- NYU Pain Research Center, New York University College of DentistryNew YorkUnited States
| | - Adam Wright
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen’s University BelfastBelfastUnited Kingdom
| | | | - Alex Rojas Bie Thomsen
- Department of Molecular Pathobiology, New York University College of DentistryNew YorkUnited States
- NYU Pain Research Center, New York University College of DentistryNew YorkUnited States
| | - Bianca Plouffe
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen’s University BelfastBelfastUnited Kingdom
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5
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Daly C, Guseinov AA, Hahn H, Wright A, Tikhonova IG, Thomsen ARB, Plouffe B. β-arrestin-dependent and -independent endosomal G protein activation by the vasopressin type 2 receptor. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.01.535208. [PMID: 37034816 PMCID: PMC10081317 DOI: 10.1101/2023.04.01.535208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
The vasopressin type 2 receptor (V2R) is an essential GPCR in renal regulation of water homeostasis. Upon stimulation, the V2R activates Gαs and Gαq/11, which is followed by robust recruitment of β-arrestins and receptor internalization into endosomes. Unlike canonical GPCR signaling, the β-arrestin association with the V2R does not terminate Gαs activation, and thus, Gαs-mediated signaling is sustained while the receptor is internalized. Here, we demonstrate that this V2R ability to co-interact with G protein/β-arrestin and promote endosomal G protein signaling is not restricted to Gαs, but also involves Gαq/11. Furthermore, our data implies that β-arrestins potentiate Gαs/Gαq/11 activation at endosomes rather than terminating their signaling. Surprisingly, we found that the V2R internalizes and promote endosomal G protein activation independent of β-arrestins to a minor degree. These new observations challenge the current model of endosomal GPCR signaling and suggest that this event can occur in both β-arrestin-dependent and -independent manners.
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Affiliation(s)
- Carole Daly
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, UK
| | | | - Hyunggu Hahn
- Department of Molecular Pathobiology, New York University College of Dentistry, New York, USA
- NYU Pain Research Center, New York University College of Dentistry, New York, USA
| | - Adam Wright
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, UK
| | | | - Alex Rojas Bie Thomsen
- Department of Molecular Pathobiology, New York University College of Dentistry, New York, USA
- NYU Pain Research Center, New York University College of Dentistry, New York, USA
| | - Bianca Plouffe
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, UK
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Erdélyi LS, Hunyady L, Balla A. V2 vasopressin receptor mutations: future personalized therapy based on individual molecular biology. Front Endocrinol (Lausanne) 2023; 14:1173601. [PMID: 37293495 PMCID: PMC10244717 DOI: 10.3389/fendo.2023.1173601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Accepted: 05/15/2023] [Indexed: 06/10/2023] Open
Abstract
The diluting and concentrating function of the kidney plays a crucial role in regulating the water homeostasis of the body. This function is regulated by the antidiuretic hormone, arginine vasopressin through the type 2 vasopressin receptor (V2R), allowing the body to adapt to periods of water load or water restriction. Loss-of-function mutations of the V2R cause X-linked nephrogenic diabetes insipidus (XNDI), which is characterized by polyuria, polydipsia, and hyposthenuria. Gain-of-function mutations of the V2R lead to nephrogenic syndrome of inappropriate antidiuresis disease (NSIAD), which results in hyponatremia. Various mechanisms may be responsible for the impaired receptor functions, and this review provides an overview of recent findings about the potential therapeutic interventions in the light of the current experimental data.
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Affiliation(s)
- László Sándor Erdélyi
- Department of Anesthesiology and Intensive Therapy, Semmelweis University, Budapest, Hungary
| | - László Hunyady
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
- Institute of Enzymology, Research Center for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
| | - András Balla
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
- ELKH-SE Laboratory of Molecular Physiology, Eötvös Loránd Research Network, Budapest, Hungary
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7
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AQP2 trafficking in health and diseases: an updated overview. Int J Biochem Cell Biol 2022; 149:106261. [DOI: 10.1016/j.biocel.2022.106261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Revised: 05/25/2022] [Accepted: 06/30/2022] [Indexed: 11/23/2022]
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Clinical, Genetic and Functional Characterization of a Novel AVPR2 Missense Mutation in a Woman with X-Linked Recessive Nephrogenic Diabetes Insipidus. J Pers Med 2022; 12:jpm12010118. [PMID: 35055433 PMCID: PMC8779739 DOI: 10.3390/jpm12010118] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 12/27/2021] [Accepted: 01/05/2022] [Indexed: 11/28/2022] Open
Abstract
Nephrogenic diabetes insipidus (NDI) is a rare disorder characterized by renal unresponsiveness to the hormone vasopressin, leading to excretion of large volumes of diluted urine. Mutations in the arginine vasopressin receptor-2 (AVPR2) gene cause congenital NDI and have an X-linked recessive inheritance. The disorder affects almost exclusively male family members, but female carriers occasionally present partial phenotypes due to skewed inactivation of the X-chromosome. Here, we report a rare case of a woman affected with X-linked recessive NDI, presenting an average urinary output of 12 L/day. Clinical and biochemical studies showed incomplete responses to water deprivation and vasopressin stimulation tests. Genetic analyses revealed a novel heterozygous missense mutation (c.493G > C, p.Ala165Pro) in the AVPR2 gene. Using a combination of in-silico protein modeling with human cellular models and molecular phenotyping, we provide functional evidence for phenotypic effects. The mutation destabilizes the helical structure of the AVPR2 transmembrane domains and disrupts its plasma membrane localization and downstream intracellular signaling pathways upon activation with its agonist vasopressin. These defects lead to deficient aquaporin 2 (AQP2) membrane translocation, explaining the inability to concentrate urine in this patient.
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Bardanzellu F, Marcialis MA, Frassetto R, Melis A, Fanos V. Differential diagnosis between syndrome of inappropriate antidiuretic hormone secretion and cerebral/renal salt wasting syndrome in children over 1 year: proposal for a simple algorithm. Pediatr Nephrol 2022; 37:1469-1478. [PMID: 34468821 PMCID: PMC9192468 DOI: 10.1007/s00467-021-05250-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 06/28/2021] [Accepted: 07/15/2021] [Indexed: 11/24/2022]
Abstract
Hyponatremia, especially if acute and severe, can be a life-threatening condition. Several conditions can trigger hyponatremia. In this review, we will discuss two conditions that can determine euvolemic hyponatremia: the cerebral/renal salt wasting (CRSW) syndrome and the syndrome of inappropriate secretion of antidiuretic hormone (SIADH), including the two subtypes: reset osmostat (RO) and nephrogenic syndrome of inappropriate antidiuresis (NSIAD) and their differential diagnoses. Despite the passage of over 70 years since its first description, to date, the true etiopathogenesis of CRSW syndrome, a rare cause of hypovolemic/euvolemic hyponatremia, is almost unknown. SIADH, including RO and NSIAD, is sometimes difficult to differentiate from CRSW syndrome; in its differential diagnosis, the clinical approach based on the evaluation of the extracellular volume (ECV) was proven insufficient. We therefore suggest a simple diagnostic algorithm based on the assessment of the degree of hyponatremia, urinary osmolality, and the assessment of the fraction of urate excretion (FEUa) in conditions of hyponatremia and after serum sodium correction, to be applied in children over 1 year of life.
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Affiliation(s)
- Flaminia Bardanzellu
- Neonatal Intensive Care Unit, Department of Surgical Sciences, AOU and University of Cagliari, SS 554 km 4, 500, 09042, Monserrato, Italy.
| | - Maria Antonietta Marcialis
- grid.7763.50000 0004 1755 3242Neonatal Intensive Care Unit, Department of Surgical Sciences, AOU and University of Cagliari, SS 554 km 4, 500, 09042 Monserrato, Italy
| | - Roberta Frassetto
- grid.7763.50000 0004 1755 3242Neonatal Intensive Care Unit, Department of Surgical Sciences, AOU and University of Cagliari, SS 554 km 4, 500, 09042 Monserrato, Italy
| | - Alice Melis
- grid.7763.50000 0004 1755 3242Neonatal Intensive Care Unit, Department of Surgical Sciences, AOU and University of Cagliari, SS 554 km 4, 500, 09042 Monserrato, Italy
| | - Vassilios Fanos
- grid.7763.50000 0004 1755 3242Neonatal Intensive Care Unit, Department of Surgical Sciences, AOU and University of Cagliari, SS 554 km 4, 500, 09042 Monserrato, Italy
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Abrol R, Serrano E, Santiago LJ. Development of enhanced conformational sampling methods to probe the activation landscape of GPCRs. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2021; 128:325-359. [PMID: 35034722 DOI: 10.1016/bs.apcsb.2021.11.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
G protein-coupled receptors (GPCRs) make up the largest superfamily of integral membrane proteins and play critical signal transduction roles in many physiological processes. Developments in molecular biology, biophysical, biochemical, pharmacological, and computational techniques aimed at these important therapeutic targets are beginning to provide unprecedented details on the structural as well as functional basis of their pleiotropic signaling mediated by G proteins, β arrestins, and other transducers. This pleiotropy presents a pharmacological challenge as the same ligand-receptor interaction can cause a therapeutic effect as well as an undesirable on-target side-effect through different downstream pathways. GPCRs don't function as simple binary on-off switches but as finely tuned shape-shifting machines described by conformational ensembles, where unique subsets of conformations may be responsible for specific signaling cascades. X-ray crystallography and more recently cryo-electron microscopy are providing snapshots of some of these functionally-important receptor conformations bound to ligands and/or transducers, which are being utilized by computational methods to describe the dynamic conformational energy landscape of GPCRs. In this chapter, we review the progress in computational conformational sampling methods based on molecular dynamics and discrete sampling approaches that have been successful in complementing biophysical and biochemical studies on these receptors in terms of their activation mechanisms, allosteric effects, actions of biased ligands, and effects of pathological mutations. Some of the sampled simulation time scales are beginning to approach receptor activation time scales. The list of conformational sampling methods and example uses discussed is not exhaustive but includes representative examples that have pushed the limits of classical molecular dynamics and discrete sampling methods to describe the activation energy landscape of GPCRs.
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Affiliation(s)
- Ravinder Abrol
- Department of Chemistry and Biochemistry, California State University, Northridge, CA, United States.
| | - Erik Serrano
- Department of Chemistry and Biochemistry, California State University, Northridge, CA, United States
| | - Luis Jaimes Santiago
- Department of Chemistry and Biochemistry, California State University, Northridge, CA, United States
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Valenti G, Tamma G. The vasopressin-aquaporin-2 pathway syndromes. HANDBOOK OF CLINICAL NEUROLOGY 2021; 181:249-259. [PMID: 34238461 DOI: 10.1016/b978-0-12-820683-6.00018-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Vasopressin is the key hormone involved in water conservation and regulation of water balance, essential for life. In the renal collecting duct, vasopressin binds to the V2 receptor, increasing water permeability through activation of aquaporin-2 redistribution to the luminal membrane. This mechanism promotes rapid water reabsorption, important for immediate survival; however, only recently it has become clear that long-term adverse effects are associated with alterations of the vasopressin-aquaporin-2 pathway, leading to several syndromes associated with water balance disorders. The kidney resistance to the vasopressin action may cause severe dehydration for patients and, conversely, nonosmotic release of vasopressin is associated with water retention and increasing the circulatory blood volume. This chapter discusses the relevance of the altered vasopressin-aquaporin-2 pathway in some diseases associated with water balance disorders, including congenital nephrogenic diabetes insipidus, syndrome of inappropriate secretion of antidiuretic hormone, nephrogenic syndrome of inappropriate antidiuresis, and autosomal dominant polycystic kidney disease. The emerging picture suggests that targeting the vasopressin-AQP2 axis can provide therapeutic benefits in those patients.
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Affiliation(s)
- Giovanna Valenti
- Department of Biosciences, Biotechnologies, and Biopharmaceutics, University of Bari, Bari, Italy.
| | - Grazia Tamma
- Department of Biosciences, Biotechnologies, and Biopharmaceutics, University of Bari, Bari, Italy
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Tong HF, Leung MTS, Chan CHT, Cheung HN, Mak WLT, Chen PLS. Nephrogenic syndrome of inappropriate antidiuresis - An ethnically, genetically and phenotypically diverse disorder: First report in a Chinese adult and review of published cases. Clin Chim Acta 2021; 519:214-219. [PMID: 33984325 DOI: 10.1016/j.cca.2021.05.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 05/04/2021] [Accepted: 05/07/2021] [Indexed: 11/18/2022]
Abstract
BACKGROUND Nephrogenic syndrome of inappropriate antidiuresis (NSIAD) is a rare inherited disorder characterised by hyponatraemia. To date, most reported cases are Caucasians with gain-of-function variants in AVPR2, an X-linked gene which encodes the vasopressin V2 receptor (V2R). Recently, germline gain-of-function variants in the stimulatory G protein α-subunit (Gsα) were reported to cause dominantly inherited NSIAD. CASE REPORT We report the first Chinese adult diagnosed with NSIAD. He was found to be hemizygous for R137C-V2R, the most prevalent pathogenic variant among Caucasians. After the genetic diagnosis and counselling on the importance of fluid restriction, he had no recurrence of hyponatraemia to date. LITERATURE REVIEW Case reports of NSIAD published in the English literature in PubMed were reviewed to summarise the genetic and phenotypic heterogeneity of this disorder. CONCLUSION NSIAD is ethnically, genetically and phenotypically diverse. The diagnosis should especially be considered in young patients with otherwise unexplained hyponatraemia. Target analysis of R137C-V2R should make the diagnosis in most cases. Genetic testing could confirm the diagnosis, motivate adherence to treatment, offer the possibility of genotype-guided therapy, and allow cascade screening to prevent hyponatraemia.
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Affiliation(s)
- Hok Fung Tong
- Department of Pathology, Princess Margaret Hospital, Hong Kong.
| | | | - Chun Hei Toby Chan
- Department of Pathology, Queen Elizabeth Hospital, Hong Kong; Department of Pathology, Hong Kong Children's Hospital, Hong Kong
| | - Hoi Ning Cheung
- Department of Pathology, Queen Elizabeth Hospital, Hong Kong
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Yang LK, Hou ZS, Tao YX. Biased signaling in naturally occurring mutations of G protein-coupled receptors associated with diverse human diseases. Biochim Biophys Acta Mol Basis Dis 2021; 1867:165973. [PMID: 32949766 PMCID: PMC7722056 DOI: 10.1016/j.bbadis.2020.165973] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 09/07/2020] [Accepted: 09/14/2020] [Indexed: 12/15/2022]
Abstract
G protein-coupled receptors (GPCRs) play critical roles in transmitting a variety of extracellular signals into the cells and regulate diverse physiological functions. Naturally occurring mutations that result in dysfunctions of GPCRs have been known as the causes of numerous diseases. Significant progresses have been made in elucidating the pathophysiology of diseases caused by mutations. The multiple intracellular signaling pathways, such as G protein-dependent and β-arrestin-dependent signaling, in conjunction with recent advances on biased agonism, have broadened the view on the molecular mechanism of disease pathogenesis. This review aims to briefly discuss biased agonism of GPCRs (biased ligands and biased receptors), summarize the naturally occurring GPCR mutations that cause biased signaling, and propose the potential pathophysiological relevance of biased mutant GPCRs associated with various endocrine diseases.
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Affiliation(s)
- Li-Kun Yang
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, United States
| | - Zhi-Shuai Hou
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, United States
| | - Ya-Xiong Tao
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, United States.
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14
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Girault-Sotias PE, Gerbier R, Flahault A, de Mota N, Llorens-Cortes C. Apelin and Vasopressin: The Yin and Yang of Water Balance. Front Endocrinol (Lausanne) 2021; 12:735515. [PMID: 34880830 PMCID: PMC8645901 DOI: 10.3389/fendo.2021.735515] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 10/19/2021] [Indexed: 12/21/2022] Open
Abstract
Apelin, a (neuro)vasoactive peptide, plays a prominent role in controlling body fluid homeostasis and cardiovascular functions. Experimental data performed in rodents have shown that apelin has an aquaretic effect via its central and renal actions. In the brain, apelin inhibits the phasic electrical activity of vasopressinergic neurons and the release of vasopressin from the posterior pituitary into the bloodstream and in the kidney, apelin regulates renal microcirculation and counteracts in the collecting duct, the antidiuretic effect of vasopressin occurring via the vasopressin receptor type 2. In humans and rodents, if plasma osmolality is increased by hypertonic saline infusion/water deprivation or decreased by water loading, plasma vasopressin and apelin are conversely regulated to maintain body fluid homeostasis. In patients with the syndrome of inappropriate antidiuresis, in which vasopressin hypersecretion leads to hyponatremia, the balance between apelin and vasopressin is significantly altered. In order to re-establish the correct balance, a metabolically stable apelin-17 analog, LIT01-196, was developed, to overcome the problem of the very short half-life (in the minute range) of apelin in vivo. In a rat experimental model of vasopressin-induced hyponatremia, subcutaneously (s.c.) administered LIT01-196 blocks the antidiuretic effect of vasopressin and the vasopressin-induced increase in urinary osmolality, and induces a progressive improvement in hyponatremia, suggesting that apelin receptor activation constitutes an original approach for hyponatremia treatment.
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15
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Droctové L, Lancien M, Tran VL, Susset M, Jego B, Theodoro F, Kessler P, Mourier G, Robin P, Diarra SS, Palea S, Flahault A, Chorfa A, Corbani M, Llorens-Cortes C, Mouillac B, Mendre C, Pruvost A, Servent D, Truillet C, Gilles N. A snake toxin as a theranostic agent for the type 2 vasopressin receptor. Am J Cancer Res 2020; 10:11580-11594. [PMID: 33052234 PMCID: PMC7545998 DOI: 10.7150/thno.47485] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 07/04/2020] [Indexed: 01/01/2023] Open
Abstract
Rationale: MQ1, a snake toxin which targets with high nanomolar affinity and absolute selectivity for the type 2 vasopressin receptor (V2R), is a drug candidate for renal diseases and a molecular probe for imaging cells or organs expressing V2R. Methods: MQ1's pharmacological properties were characterized and applied to a rat model of hyponatremia. Its PK/PD parameters were determined as well as its therapeutic index. Fluorescently and radioactively labeled MQ1 were chemically synthesized and associated with moderate loss of affinity. MQ1's dynamic biodistribution was monitored by positron emission tomography. Confocal imaging was used to observe the labeling of three cancer cell lines. Results: The inverse agonist property of MQ1 very efficiently prevented dDAVP-induced hyponatremia in rats with low nanomolar/kg doses and with a very large therapeutic index. PK (plasma MQ1 concentrations) and PD (diuresis) exhibited a parallel biphasic decrease. The dynamic biodistribution showed that MQ1 targets the kidneys and then exhibits a blood and kidney biphasic decrease. Whatever the approach used, we found a T1/2α between 0.9 and 3.8 h and a T1/2β between 25 and 46 h and demonstrated that the kidneys were able to retain MQ1. Finally, the presence of functional V2R expressed at the membrane of cancer cells was, for the first time, demonstrated with a specific fluorescent ligand. Conclusion: As the most selective V2 binder, MQ1 is a new promising drug for aquaresis-related diseases and a molecular probe to visualize in vitro and in vivo V2R expressed physiologically or under pathological conditions.
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16
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Vezzi V, Ambrosio C, Grò MC, Molinari P, Süral G, Costa T, Onaran HO, Cotecchia S. Vasopressin receptor 2 mutations in the nephrogenic syndrome of inappropriate antidiuresis show different mechanisms of constitutive activation for G protein coupled receptors. Sci Rep 2020; 10:9111. [PMID: 32499611 PMCID: PMC7272623 DOI: 10.1038/s41598-020-65996-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 05/13/2020] [Indexed: 01/14/2023] Open
Abstract
Vasopressin receptor 2 (V2R) mutations causing the nephrogenic syndrome of inappropriate antidiuresis (NSIAD) can generate two constitutively active receptor phenotypes. One type results from residue substitutions in several V2R domains and is sensitive to vaptan inverse agonists. The other is only caused by Arg 137 replacements and is vaptan resistant. We compared constitutive and agonist-driven interactions of the vaptan-sensitive F229V and vaptan-resistant R137C/L V2R mutations with β-arrestin 1, β-arrestin 2, and Gαs, using null fibroblasts reconstituted with individual versions of the ablated transduction protein genes. F229V displayed very high level of constitutive activation for Gs but not for β-arrestins, and enhanced or normal responsiveness to agonists and inverse agonists. In contrast, R137C/L mutants exhibited maximal levels of constitutive activation for βarrestin 2 and Gs, minimal levels for β-arrestin 1, but a sharp decline of ligands sensitivity at all transducer interactions. The enhanced constitutive activity and reduced ligand sensitivity of R137 mutants on cAMP signaling persisted in cells lacking β-arrestins, indicating that these are intrinsic molecular properties of the mutations, not the consequence of altered receptor trafficking. The results suggest that the two groups of NSIAD mutations represent two distinct molecular mechanisms of constitutive activation in GPCRs.
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Affiliation(s)
- Vanessa Vezzi
- Istituto Superiore di Sanitá, National Center for Drug Research and Evaluation, Rome, Italy
| | - Caterina Ambrosio
- Istituto Superiore di Sanitá, National Center for Drug Research and Evaluation, Rome, Italy
| | - Maria Cristina Grò
- Istituto Superiore di Sanitá, National Center for Drug Research and Evaluation, Rome, Italy
| | - Paola Molinari
- Istituto Superiore di Sanitá, National Center for Drug Research and Evaluation, Rome, Italy
| | - Gökçe Süral
- Ankara University, Faculty of Medicine, Department of Pharmacology, Molecular biology and Technology development unit, Sıhhiye, Ankara, Turkey
| | - Tommaso Costa
- Istituto Superiore di Sanitá, National Center for Drug Research and Evaluation, Rome, Italy
| | - H Ongun Onaran
- Ankara University, Faculty of Medicine, Department of Pharmacology, Molecular biology and Technology development unit, Sıhhiye, Ankara, Turkey
| | - Susanna Cotecchia
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, 70125, Bari, Italy.
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17
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Ranieri M, Venneri M, Pellegrino T, Centrone M, Di Mise A, Cotecchia S, Tamma G, Valenti G. The Vasopressin Receptor 2 Mutant R137L Linked to the Nephrogenic Syndrome of Inappropriate Antidiuresis (NSIAD) Signals through an Alternative Pathway that Increases AQP2 Membrane Targeting Independently of S256 Phosphorylation. Cells 2020; 9:cells9061354. [PMID: 32486031 PMCID: PMC7349359 DOI: 10.3390/cells9061354] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 05/26/2020] [Accepted: 05/27/2020] [Indexed: 12/18/2022] Open
Abstract
NSIAD is a rare X-linked condition, caused by activating mutations in the AVPR2 gene coding for the vasopressin V2 receptor (V2R) associated with hyponatremia, despite undetectable plasma vasopressin levels. We have recently provided in vitro evidence that, compared to V2R-wt, expression of activating V2R mutations R137L, R137C and F229V cause a constitutive redistribution of the AQP2 water channel to the plasma membrane, higher basal water permeability and significantly higher basal levels of p256-AQP2 in the F229V mutant but not in R137L or R137C. In this study, V2R mutations were expressed in collecting duct principal cells and the associated signalling was dissected. V2R-R137L and R137C mutants had significantly higher basal pT269-AQP2 levels -independently of S256 and PKA-which were reduced to control by treatment with Rho kinase (ROCK) inhibitor. Interestingly, ROCK activity was found significantly higher in V2R-R137L along with activation of the Gα12/13–Rho–ROCK pathway. Of note, inhibition of ROCK reduced the basal elevated osmotic water permeability to control. To conclude, our data demonstrate for the first time that the gain-of-function mutation of the V2R, R137L causing NSIAD, signals through an alternative PKA-independent pathway that increases AQP2 membrane targeting through ROCK-induced phosphorylation at S/T269 independently of S256 of AQP2.
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Affiliation(s)
- Marianna Ranieri
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, 70125 Bari, Italy; (M.R.); (M.V.); (T.P.); (M.C.); (A.D.M.); (S.C.); (G.T.)
| | - Maria Venneri
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, 70125 Bari, Italy; (M.R.); (M.V.); (T.P.); (M.C.); (A.D.M.); (S.C.); (G.T.)
| | - Tommaso Pellegrino
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, 70125 Bari, Italy; (M.R.); (M.V.); (T.P.); (M.C.); (A.D.M.); (S.C.); (G.T.)
| | - Mariangela Centrone
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, 70125 Bari, Italy; (M.R.); (M.V.); (T.P.); (M.C.); (A.D.M.); (S.C.); (G.T.)
| | - Annarita Di Mise
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, 70125 Bari, Italy; (M.R.); (M.V.); (T.P.); (M.C.); (A.D.M.); (S.C.); (G.T.)
| | - Susanna Cotecchia
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, 70125 Bari, Italy; (M.R.); (M.V.); (T.P.); (M.C.); (A.D.M.); (S.C.); (G.T.)
| | - Grazia Tamma
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, 70125 Bari, Italy; (M.R.); (M.V.); (T.P.); (M.C.); (A.D.M.); (S.C.); (G.T.)
- Istituto Nazionale di Biostrutture e Biosistemi, 00136 Roma, Italy
| | - Giovanna Valenti
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, 70125 Bari, Italy; (M.R.); (M.V.); (T.P.); (M.C.); (A.D.M.); (S.C.); (G.T.)
- Istituto Nazionale di Biostrutture e Biosistemi, 00136 Roma, Italy
- Center of Excellence in Comparative Genomics (CEGBA), University of Bari, 70125 Bari, Italy
- Correspondence: ; Tel.: +39-080-5443444
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18
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Makita N, Manaka K, Sato J, Iiri T. V2 vasopressin receptor mutations. VITAMINS AND HORMONES 2019; 113:79-99. [PMID: 32138955 DOI: 10.1016/bs.vh.2019.08.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
V2 vasopressin receptor (V2R) is a member of the G protein-coupled receptor (GPCR) family in which many disease-causing mutations have been identified and thus generated much interest. Loss-of-function V2R mutations cause nephrogenic diabetes insipidus (NDI) whereas gain-of-function mutations cause nephrogenic syndrome of inappropriate antidiuresis (NSIAD). The mechanisms underlying a V2R loss-of-function can be theoretically classified as either protein expression, localization (ER retention) or functional disorders. Functional analyses have revealed however that these mechanisms are likely to be complex. Strikingly, V2R mutations at the same site can result in opposite phenotypes, e.g., R137H and R137L/C cause NDI and NSIAD, respectively. These findings support the notion that the constitutive activation of GPCRs might be often associated with their instability and denaturation. Thus, functional analysis of disease-causing V2R mutations may not only reveal potential new treatment strategies using pharmacochaperones for NDI and inverse agonists for NSIAD, but also provide a greater understanding of the physiological functions of GPCRs and highlight the new paradigms, i.e., biased agonism and protean agonism.
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Affiliation(s)
- Noriko Makita
- Department of Endocrinology and Nephrology, The University of Tokyo, Tokyo, Japan.
| | - Katsunori Manaka
- Department of Endocrinology and Nephrology, The University of Tokyo, Tokyo, Japan
| | - Junichiro Sato
- Department of Endocrinology and Nephrology, The University of Tokyo, Tokyo, Japan
| | - Taroh Iiri
- Department of Endocrinology and Nephrology, The University of Tokyo, Tokyo, Japan; Department of Pharmacology, St. Marianna University School of Medicine, Kawasaki, Japan.
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19
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Ranieri M, Tamma G, Pellegrino T, Vezzi V, Ambrosio C, Grò C, Di Mise A, Costa T, Valenti G, Cotecchia S. Gain-of-function mutations of the V2 vasopressin receptor in nephrogenic syndrome of inappropriate antidiuresis (NSIAD): a cell-based assay to assess constitutive water reabsorption. Pflugers Arch 2019; 471:1291-1304. [PMID: 31486901 DOI: 10.1007/s00424-019-02307-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 08/28/2019] [Accepted: 08/29/2019] [Indexed: 12/31/2022]
Abstract
Nephrogenic syndrome of inappropriate antidiuresis (NSIAD) is a recently identified chromosome X-linked disease associated with gain-of-function mutations of the V2 vasopressin receptor (V2R), a G-protein-coupled receptor. It is characterized by inability to excrete a free water load, hyponatremia, and undetectable vasopressin-circulating levels. Hyponatremia can be quite severe in affected male children. To gain a deeper insight into the functional properties of the V2R active mutants and how they might translate into the pathological outcome of NSIAD, in this study, we have expressed the wild-type V2R and three constitutively active V2R mutants associated with NSIAD (R137L, R137C, and the F229V) in MCD4 cells, a cell line derived from renal mouse collecting duct, stably expressing the vasopressin-sensitive water channel aquaporin-2 (AQP2). Our findings indicate that in cells expressing each active mutant, AQP2 was constitutively localized to the apical plasma membrane in the absence of vasopressin stimulation. In line with these observations, under basal conditions, osmotic water permeability in cells expressing the constitutively active mutants was significantly higher compared to that of cells expressing the wild-type V2R. Our findings demonstrate a direct link between activating mutations of the V2R and the perturbation of water balance in NSIAD. In addition, this study provides a useful cell-based assay system to assess the functional consequences of newly discovered activating mutations of the V2R on water permeability in kidney cells and to screen the effect of drugs on the mutated receptors.
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Affiliation(s)
- Marianna Ranieri
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, 70125, Bari, Italy
| | - Grazia Tamma
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, 70125, Bari, Italy.,Istituto Nazionale di Biostrutture e Biosistemi, 00136, Rome, Italy
| | - Tommaso Pellegrino
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, 70125, Bari, Italy
| | - Vanessa Vezzi
- Department of Pharmacology, Istituto Superiore di Sanità, 00161, Rome, Italy
| | - Caterina Ambrosio
- Department of Pharmacology, Istituto Superiore di Sanità, 00161, Rome, Italy
| | - Cristina Grò
- Department of Pharmacology, Istituto Superiore di Sanità, 00161, Rome, Italy
| | - Annarita Di Mise
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, 70125, Bari, Italy
| | - Tommaso Costa
- Department of Pharmacology, Istituto Superiore di Sanità, 00161, Rome, Italy
| | - Giovanna Valenti
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, 70125, Bari, Italy. .,Istituto Nazionale di Biostrutture e Biosistemi, 00136, Rome, Italy. .,Center of Excellence in Comparative Genomics (CEGBA), University of Bari, 70125, Bari, Italy.
| | - Susanna Cotecchia
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, 70125, Bari, Italy.
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20
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Bardanzellu F, Pintus MC, Masile V, Fanos V, Marcialis MA. Focus on neonatal and infantile onset of nephrogenic syndrome of inappropriate antidiuresis: 12 years later. Pediatr Nephrol 2019; 34:763-775. [PMID: 29546600 DOI: 10.1007/s00467-018-3922-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2017] [Revised: 02/09/2018] [Accepted: 02/09/2018] [Indexed: 11/25/2022]
Abstract
Nephrogenic syndrome of inappropriate antidiuresis (NSIAD), first described in 2005, is a rare genetic X-linked disease, presenting with hyponatremia, hyposmolarity, euvolemia, inappropriately concentrated urine, increased natriuresis, and undetectable or very low arginine-vasopressine (AVP) circulating levels. It can occur in neonates, infants, or later in life. NSIAD must be early recognized and treated to prevent severe hyponatremia, which can show a dangerous impact on neonatal outcome. In fact, it potentially leads to death or, in case of survival, neurologic sequelae. This review is an update of NSIAD 12 years after the first description, focusing on reported cases of neonatal and infantile onset. The different molecular patterns affecting the AVP receptor 2 (V2R) and determining its gain of function are reported in detail; moreover, we also provide a comparison between the different triggers involved in the development of hyponatremia, the evolution of the symptoms, and modality and efficacy of the different treatments available.
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Affiliation(s)
- Flaminia Bardanzellu
- Neonatal Intensive Care Unit, Neonatal Pathology and Neonatal Section, AOU and University of Cagliari, Cagliari, Italy.
| | - Maria Cristina Pintus
- Neonatal Intensive Care Unit, Neonatal Pathology and Neonatal Section, AOU and University of Cagliari, Cagliari, Italy
| | - Valentina Masile
- Neonatal Intensive Care Unit, Neonatal Pathology and Neonatal Section, AOU and University of Cagliari, Cagliari, Italy
| | - Vassilios Fanos
- Neonatal Intensive Care Unit, Neonatal Pathology and Neonatal Section, AOU and University of Cagliari, Cagliari, Italy
| | - Maria Antonietta Marcialis
- Neonatal Intensive Care Unit, Neonatal Pathology and Neonatal Section, AOU and University of Cagliari, Cagliari, Italy
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21
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Miyado M, Fukami M, Takada S, Terao M, Nakabayashi K, Hata K, Matsubara Y, Tanaka Y, Sasaki G, Nagasaki K, Shiina M, Ogata K, Masunaga Y, Saitsu H, Ogata T. Germline-Derived Gain-of-Function Variants of Gs α-Coding GNAS Gene Identified in Nephrogenic Syndrome of Inappropriate Antidiuresis. J Am Soc Nephrol 2019; 30:877-889. [PMID: 30962325 DOI: 10.1681/asn.2018121268] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Accepted: 02/02/2019] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND The stimulatory G-protein α-subunit encoded by GNAS exons 1-13 (GNAS-Gsα) mediates signal transduction of multiple G protein-coupled receptors, including arginine vasopressin receptor 2 (AVPR2). Various germline-derived loss-of-function GNAS-Gsα variants of maternal and paternal origin have been found in pseudohypoparathyroidism type Ia and pseudopseudohypoparathyroidism, respectively. Specific somatic gain-of-function GNAS-Gsα variants have been detected in McCune-Albright syndrome and may result in phosphate wasting. However, no germline-derived gain-of-function variant has been identified, implying that such a variant causes embryonic lethality. METHODS We performed whole-exome sequencing in two families with dominantly inherited nephrogenic syndrome of inappropriate antidiuresis (NSIAD) as a salient phenotype after excluding a gain-of-function variant of AVPR2 and functional studies for identified variants. RESULTS Whole-exome sequencing revealed two GNAS-Gsα candidate variants for NSIAD: GNAS-Gsα p.(F68_G70del) in one family and GNAS-Gsα p.(M255V) in one family. Both variants were absent from public and in-house databases. Of genes with rare variants, GNAS-Gsα alone was involved in AVPR2 signaling and shared by the families. Protein structural analyses revealed a gain-of-function-compatible conformational property for p.M255V-Gsα, although such assessment was not possible for p.F68_G70del-Gsα. Both variants had gain-of-function effects that were significantly milder than those of McCune-Albright syndrome-specific somatic Gsα variants. Model mice for p.F68_G70del-Gsα showed normal survivability and NSIAD-compatible phenotype, whereas those for p.M255V-Gsα exhibited severe failure to thrive. CONCLUSIONS This study shows that germline-derived gain-of-function rare variants of GNAS-Gsα exist and cause NSIAD as a novel Gsα-mediated genetic disease. It is likely that AVPR2 signaling is most sensitive to GNAS-Gsα's gain-of-function effects.
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Affiliation(s)
| | | | | | | | | | | | - Yoichi Matsubara
- Head Office, National Research Institute for Child Health and Development, Tokyo, Japan
| | - Yoko Tanaka
- Department of Pediatrics, Tokyo Dental College, Ichikawa General Hospital, Ichikawa, Japan
| | - Goro Sasaki
- Department of Pediatrics, Tokyo Dental College, Ichikawa General Hospital, Ichikawa, Japan
| | - Keisuke Nagasaki
- Department of Homeostatic Regulation and Development, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Masaaki Shiina
- Department of Biochemistry, Yokohama City University Graduate School of Medicine, Yokohama, Japan; and
| | - Kazuhiro Ogata
- Department of Biochemistry, Yokohama City University Graduate School of Medicine, Yokohama, Japan; and
| | | | - Hirotomo Saitsu
- Biochemistry, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Tsutomu Ogata
- Departments of Molecular Endocrinology, .,Departments of Pediatrics and
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22
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Ranieri M, Di Mise A, Tamma G, Valenti G. Vasopressin-aquaporin-2 pathway: recent advances in understanding water balance disorders. F1000Res 2019; 8. [PMID: 30800291 PMCID: PMC6364380 DOI: 10.12688/f1000research.16654.1] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 01/23/2019] [Indexed: 12/11/2022] Open
Abstract
The alteration of water balance and related disorders has emerged as being strictly linked to the state of activation of the vasopressin–aquaporin-2
(vasopressin–AQP2) pathway. The lack of responsiveness of the kidney to the vasopressin action impairs its ability to concentrate the urine, resulting in polyuria, polydipsia, and risk of severe dehydration for patients. Conversely, non-osmotic release of vasopressin is associated with an increase in water permeability in the renal collecting duct, producing water retention and increasing the circulatory blood volume. This review highlights some of the new insights and recent advances in therapeutic intervention targeting the dysfunctions in the vasopressin–AQP2 pathway causing diseases characterized by water balance disorders such as congenital nephrogenic diabetes insipidus, syndrome of inappropriate antidiuretic hormone secretion, nephrogenic syndrome of inappropriate antidiuresis, and autosomal dominant polycystic kidney disease. The recent clinical data suggest that targeting the vasopressin–AQP2 axis can provide therapeutic benefits in patients with water balance disorders.
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Affiliation(s)
- Marianna Ranieri
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy, 70125, Italy
| | - Annarita Di Mise
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy, 70125, Italy
| | - Grazia Tamma
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy, 70125, Italy.,Istituto Nazionale di Biostrutture e Biosistemi, Rome, Roma, Italy, 00136, Italy
| | - Giovanna Valenti
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy, 70125, Italy.,Istituto Nazionale di Biostrutture e Biosistemi, Rome, Roma, Italy, 00136, Italy.,Center of Excellence in Comparative Genomics (CEGBA), University of Bari, Bari, Italy, 70125, Italy
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23
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Abstract
Body fluid homeostasis is essential for normal life. In the maintenance of water balance, the most important factor and regulated process is the excretory function of the kidneys. The kidneys are capable to compensate not only the daily fluctuations of water intake but also the consequences of fluid loss (respiration, perspiration, sweating, hemorrhage). The final volume and osmolality of the excreted urine is set in the collecting duct via hormonal regulation. The hormone of water conservation is the vasopressin (AVP), and a large volume of urine is produced and excreted in the absence of AVP secretion or if AVP is ineffective in the kidneys. The aquaporin-2 water channel (AQP2) is expressed in the principal cells, and it plays an essential role in the reabsorption of water in the collecting ducts via type 2 vasopressin receptor (V2R)-mediated mechanism. If neural or hormonal regulation fails to operate the normal function of AVP-V2R-AQP2 system, it can result in various diseases such as diabetes insipidus (DI) or nephrogenic syndrome of inappropriate diuresis (NSIAD). The DI is characterized by excessive production of hyposmotic urine ("insipidus" means tasteless) due to the inability of the kidneys to concentrate urine. In this chapter, we focus and discuss the pathophysiology of nephrogenic DI (NDI) and the potential therapeutic interventions in the light of the current experimental data.
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Affiliation(s)
- András Balla
- Faculty of Medicine, Department of Physiology, Semmelweis University, Budapest, Hungary
- MTA-SE Laboratory of Molecular Physiology, Hungarian Academy of Sciences, Semmelweis University, Budapest, Hungary
| | - László Hunyady
- Faculty of Medicine, Department of Physiology, Semmelweis University, Budapest, Hungary.
- MTA-SE Laboratory of Molecular Physiology, Hungarian Academy of Sciences, Semmelweis University, Budapest, Hungary.
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24
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Fukami M, Suzuki E, Igarashi M, Miyado M, Ogata T. Gain-of-function mutations in G-protein-coupled receptor genes associated with human endocrine disorders. Clin Endocrinol (Oxf) 2018; 88:351-359. [PMID: 29029377 DOI: 10.1111/cen.13496] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Revised: 10/08/2017] [Accepted: 10/09/2017] [Indexed: 11/28/2022]
Abstract
The human genome encodes more than 700 G-protein-coupled receptors (GPCRs), many of which are involved in hormone secretion. To date, more than 100 gain-of-function (activating) mutations in at least ten genes for GPCRs, in addition to several loss-of-function mutations, have been implicated in human endocrine disorders. Previously reported gain-of-function GPCR mutations comprise various missense substitutions, frameshift mutations, intragenic inframe deletions and copy-number gains. Such mutations appear in both germline and somatic tumour cells, and lead to various hormonal abnormalities reflecting excessive receptor activity. Phenotypic consequences of these mutations include distinctive endocrine syndromes, as well as relatively common hormonal abnormalities. Such mutations encode hyperfunctioning receptors with increased constitutive activity, broadened ligand specificity, increased ligand sensitivity and/or delayed receptor desensitization. Furthermore, recent studies proposed a paradoxical gain-of-function mechanism caused by inactive GPCR mutants. Molecular diagnosis of GPCR activating mutations serves to improve the clinical management of mutation-positive patients. This review aims to introduce new aspects regarding gain-of-function mutations in GPCR genes associated with endocrine disorders.
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Affiliation(s)
- Maki Fukami
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo, Japan
| | - Erina Suzuki
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo, Japan
| | - Maki Igarashi
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo, Japan
| | - Mami Miyado
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo, Japan
| | - Tsutomu Ogata
- Department of Pediatrics, Hamamatsu University School of Medicine, Hamamatsu, Japan
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Erdem B, Schulz A, Saglar E, Deniz F, Schöneberg T, Mergen H. Functional characterization of AVPR2 mutants found in Turkish patients with nephrogenic diabetes insipidus. Endocr Connect 2018; 7:56-64. [PMID: 29117938 PMCID: PMC5744627 DOI: 10.1530/ec-17-0236] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 11/08/2017] [Indexed: 11/15/2022]
Abstract
Diabetes insipidus is a rare disorder characterized by an impairment in water balance because of the inability to concentrate urine. While central diabetes insipidus is caused by mutations in the AVP, the reason for genetically determined nephrogenic diabetes insipidus can be mutations in AQP2 or AVPR2 After release of AVP from posterior pituitary into blood stream, it binds to AVPR2, which is one of the receptors for AVP and is mainly expressed in principal cells of collecting ducts of kidney. Receptor activation increases cAMP levels in principal cells, resulting in the incorporation of AQP2 into the membrane, finally increasing water reabsorption. This pathway can be altered by mutations in AVPR2 causing nephrogenic diabetes insipidus. In this study, we functionally characterize four mutations (R68W, ΔR67-G69/G107W, V162A and T273M) in AVPR2, which were found in Turkish patients. Upon AVP stimulation, R68W, ΔR67-G69/G107W and T273M showed a significantly reduced maximum in cAMP response compared to wild-type receptor. All mutant receptor proteins were expressed at the protein level; however, R68W, ΔR67-G69/G107W and T273M were partially retained in the cellular interior. Immunofluorescence studies showed that these mutant receptors were trapped in ER and Golgi apparatus. The function of V162A was indistinguishable from the indicating other defects causing disease. The results are important for understanding the influence of mutations on receptor function and cellular trafficking. Therefore, characterization of these mutations provides useful information for further studies addressing treatment of intracellularly trapped receptors with cell-permeable antagonists to restore receptor function in patients with nephrogenic diabetes insipidus.
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Affiliation(s)
- Beril Erdem
- Department of BiologyFaculty of Science, Hacettepe University, Ankara, Turkey
| | - Angela Schulz
- Rudolf Schönheimer Institute of BiochemistryFaculty of Medicine, Leipzig University, Leipzig, Germany
| | - Emel Saglar
- Department of BiologyFaculty of Science, Hacettepe University, Ankara, Turkey
| | - Ferhat Deniz
- Department of EndocrinologySBÜ Sultan Abdülhamid Han Teaching Hospital, Istanbul, Turkey
| | - Torsten Schöneberg
- Rudolf Schönheimer Institute of BiochemistryFaculty of Medicine, Leipzig University, Leipzig, Germany
| | - Hatice Mergen
- Department of BiologyFaculty of Science, Hacettepe University, Ankara, Turkey
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26
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Cailleaux A, Mahieu F, Heinrichs C, Adams B, Ismaili K, Brachet C. [Nephrogenic syndrome of inappropriate antidiuresis: Early diagnosis avoids severe hyponatremia complications]. Arch Pediatr 2017; 24:630-633. [PMID: 28583780 DOI: 10.1016/j.arcped.2017.04.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 01/10/2017] [Accepted: 04/19/2017] [Indexed: 11/18/2022]
Abstract
AIM Nephrogenic syndrome of inappropriate antidiuresis (NSIAD) is a rare disease characterized by a kidney disability to dilute urine and, as a result, severe recurrent hyponatremia. Due to wide variability in clinical expression, the diagnosis still remains a challenge for clinicians. We report our experience of a case in which NSIAD was diagnosed early. We also stress the importance of early diagnosis and treatment, which protects an infant with NSAID from severe hyponatremia. BACKGROUND A 1-month-old boy was referred to our hospital for persistent hyponatremia and intense vomiting. He was born full term after a normal pregnancy with a normal birth weight. The parents were healthy, nonconsanguineous, of Moroccan origin. They already had healthy twin girls. The physical examination was normal upon admission with no signs of dehydration and normal weight gain since birth. Plasma sodium was very low (125mmol/L) associated with low plasma urea (5mg/dL), osmolality (258 mOsm/kg) and low natriuresis (59mmol/L). These laboratory results suggested inappropriate antidiuretic hormone secretion (SIAD) and the infant was consequently treated with oral urea (he was already receiving sodium supplements that were later stopped). Due to exclusive breastfeeding, water restriction was impossible. Further biological investigation revealed undetectable plasma arginine vasopressin (AVP), suggesting the diagnosis of NSIAD. This was confirmed by genetic sequencing of the AVP receptor (AVPR2), demonstrating the presence of an R137C mutation. CONCLUSIONS We herein report a case of a genetic fluid balance disorder due to an activating mutation of AVPR2. NSIAD is an X-linked disease, first described in 2005 by Feldman et al., which involved severe recurrent hyponatremia. The very early diagnosis (at 7 weeks of life) and appropriate treatment with urea prevented seizures and cerebral damage due to severe recurrent hyponatremia. Clinicians should consider the diagnosis of NSIAD in infants with recurrent hyponatremia with hemodilution and low AVP serum level. Genetic analysis of the AVPR2 sequence on the X chromosome will confirm the diagnosis and, given the wide variability of clinical expression, sequencing of the family members should be done.
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Affiliation(s)
- A Cailleaux
- Pediatric Nephrology unit, hôpital universitaire des Enfants-Reine-Fabiola, n(o) 15, avenue J.J.-Crocq, 1020 Bruxelles, Belgique.
| | - F Mahieu
- Pediatric Department, centre hospitalier universitaire de Tivoli, n(o) 34, avenue Max-Buset, 7100 La Louvière, Belgique
| | - C Heinrichs
- Pediatric Endocrinology unit, hôpital universitaire des Enfants-Reine-Fabiola, n(o) 15, avenue J.J.-Crocq, 1020 Bruxelles, Belgique
| | - B Adams
- Pediatric Nephrology unit, hôpital universitaire des Enfants-Reine-Fabiola, n(o) 15, avenue J.J.-Crocq, 1020 Bruxelles, Belgique
| | - K Ismaili
- Pediatric Nephrology unit, hôpital universitaire des Enfants-Reine-Fabiola, n(o) 15, avenue J.J.-Crocq, 1020 Bruxelles, Belgique
| | - C Brachet
- Pediatric Endocrinology unit, hôpital universitaire des Enfants-Reine-Fabiola, n(o) 15, avenue J.J.-Crocq, 1020 Bruxelles, Belgique
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Tamma G, Di Mise A, Ranieri M, Geller A, Tamma R, Zallone A, Valenti G. The V2 receptor antagonist tolvaptan raises cytosolic calcium and prevents AQP2 trafficking and function: an in vitro and in vivo assessment. J Cell Mol Med 2017; 21:1767-1780. [PMID: 28326667 PMCID: PMC5571526 DOI: 10.1111/jcmm.13098] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 12/21/2016] [Indexed: 01/07/2023] Open
Abstract
Tolvaptan, a selective vasopressin V2 receptor antagonist, is a new generation diuretic. Its clinical efficacy is in principle due to impaired vasopressin‐regulated water reabsorption via aquaporin‐2 (AQP2). Nevertheless, no direct in vitro evidence that tolvaptan prevents AQP2‐mediated water transport, nor that this pathway is targeted in vivo in patients with syndrome of inappropriate antidiuresis (SIAD) has been provided. The effects of tolvaptan on the vasopressin–cAMP/PKA signalling cascade were investigated in MDCK cells expressing endogenous V2R and in mouse kidney. In MDCK, tolvaptan prevented dDAVP‐induced increase in ser256‐AQP2 and osmotic water permeability. A similar effect on ser256‐AQP2 was found in V1aR −/− mice, thus confirming the V2R selectively. Of note, calcium calibration in MDCK showed that tolvaptan per se caused calcium mobilization from the endoplasmic reticulum resulting in a significant increase in basal intracellular calcium. This effect was only observed in cells expressing the V2R, indicating that it requires the tolvaptan–V2R interaction. Consistent with this finding, tolvaptan partially reduced the increase in ser256‐AQP2 and the water permeability in response to forskolin, a direct activator of adenylyl cyclase (AC), suggesting that the increase in intracellular calcium is associated with an inhibition of the calcium‐inhibitable AC type VI. Furthermore, tolvaptan treatment reduced AQP2 excretion in two SIAD patients and normalized plasma sodium concentration. These data represent the first detailed demonstration of the central role of AQP2 blockade in the aquaretic effect of tolvaptan and underscore a novel effect in raising intracellular calcium that can be of significant clinical relevance.
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Affiliation(s)
- Grazia Tamma
- Department of Biosciences Biotechnologies and Biopharmaceutics, University of Bari Aldo Moro, Bari, Italy
| | - Annarita Di Mise
- Department of Biosciences Biotechnologies and Biopharmaceutics, University of Bari Aldo Moro, Bari, Italy
| | - Marianna Ranieri
- Department of Biosciences Biotechnologies and Biopharmaceutics, University of Bari Aldo Moro, Bari, Italy
| | | | - Roberto Tamma
- Department of Basic Medical Science, Neuroscience and Sense Organs, University of Bari Aldo Moro, Bari, Italy
| | - Alberta Zallone
- Department of Basic Medical Science, Neuroscience and Sense Organs, University of Bari Aldo Moro, Bari, Italy
| | - Giovanna Valenti
- Department of Biosciences Biotechnologies and Biopharmaceutics, University of Bari Aldo Moro, Bari, Italy
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28
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Powlson AS, Challis BG, Halsall DJ, Schoenmakers E, Gurnell M. Nephrogenic syndrome of inappropriate antidiuresis secondary to an activating mutation in the arginine vasopressin receptor AVPR2. Clin Endocrinol (Oxf) 2016; 85:306-12. [PMID: 26715131 DOI: 10.1111/cen.13011] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Revised: 11/18/2015] [Accepted: 12/23/2015] [Indexed: 01/15/2023]
Abstract
CONTEXT Nephrogenic syndrome of inappropriate antidiuresis (NSIAD), resulting from activating mutations in the arginine vasopressin receptor type 2 (AVPR2), is a rare cause of hyponatraemia. However, its true prevalence may be underestimated and it should be considered in the investigation of unexplained hyponatraemia, with implications for management and targeted gene testing. OBJECTIVE We describe a structured approach to the investigation of hyponatraemia in a young patient, which allowed a diagnosis of NSIAD to be made. We review current knowledge of NSIAD and use a structural modelling approach to further our understanding of the potential mechanisms by which the causative mutation leads to a constitutively active AVPR2. DESIGN Clinical and biochemical investigation of hyponatraemia; a formal water load test with measurement of arginine vasopressin levels (AVP); sequencing of AVPR2; and computed structural modelling of the wild-type and constitutively activated mutant receptors. RESULTS A 38-year-old man presented with intermittent confusion and nausea associated with hyponatraemia and a biochemical picture consistent with syndrome of inappropriate antidiuretic hormone (SIADH). Adrenocortical and thyroid function and an acute intermittent porphyria screen were normal. Cross-sectional imaging of the head, chest and abdomen did not identify an underlying cause and so we proceeded to a water load test. This demonstrated a marked inability to excrete a free water load (just 15% of a 20 ml/kg oral load by 240 min postingestion), with the onset of hyponatraemia (Na(+) 125 mmol/l, urine osmolality 808 mOsm/kg). However, AVP levels were low throughout the test (0·4-0·9 pmol/l), consistent with a diagnosis of NSIAD. AVPR2 sequencing revealed a previously described hemizygous activating mutation (p.Arg137Cys). Through structural modelling of AVPR2, we suggest that disruption of a hydrogen bond between residues Thr269 and Arg137 may promote stabilization of the receptor in its active conformation. Since diagnosis, the patient has adhered to modest fluid restriction and remained well, with no further episodes of hyponatraemia. CONCLUSION NSIAD should be considered in young patients with unexplained hyponatraemia. A water load test with AVP measurement is a potentially informative investigation, while AVPR2 sequencing provides a definitive molecular genetic diagnosis and a rationale for long-term fluid restriction.
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Affiliation(s)
- Andrew S Powlson
- Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, University of Cambridge & National Institute for Health Research Cambridge Biomedical Research Centre, Addenbrooke's Hospital, Cambridge, UK
| | - Benjamin G Challis
- Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, University of Cambridge & National Institute for Health Research Cambridge Biomedical Research Centre, Addenbrooke's Hospital, Cambridge, UK
| | - David J Halsall
- Department of Clinical Biochemistry, Addenbrooke's Hospital, Cambridge, UK
| | - Erik Schoenmakers
- Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, University of Cambridge & National Institute for Health Research Cambridge Biomedical Research Centre, Addenbrooke's Hospital, Cambridge, UK
| | - Mark Gurnell
- Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, University of Cambridge & National Institute for Health Research Cambridge Biomedical Research Centre, Addenbrooke's Hospital, Cambridge, UK
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Tiulpakov A, White CW, Abhayawardana RS, See HB, Chan AS, Seeber RM, Heng JI, Dedov I, Pavlos NJ, Pfleger KDG. Mutations of Vasopressin Receptor 2 Including Novel L312S Have Differential Effects on Trafficking. Mol Endocrinol 2016; 30:889-904. [PMID: 27355191 PMCID: PMC4965841 DOI: 10.1210/me.2016-1002] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Nephrogenic syndrome of inappropriate antidiuresis (NSIAD) is a genetic disease first described in 2 unrelated male infants with severe symptomatic hyponatremia. Despite undetectable arginine vasopressin levels, patients have inappropriately concentrated urine resulting in hyponatremia, hypoosmolality, and natriuresis. Here, we describe and functionally characterize a novel vasopressin type 2 receptor (V2R) gain-of-function mutation. An L312S substitution in the seventh transmembrane domain was identified in a boy presenting with water-induced hyponatremic seizures at the age of 5.8 years. We show that, compared with wild-type V2R, the L312S mutation results in the constitutive production of cAMP, indicative of the gain-of-function NSIAD profile. Interestingly, like the previously described F229V and I130N NSIAD-causing mutants, this appears to both occur in the absence of notable constitutive β-arrestin2 recruitment and can be reduced by the inverse agonist Tolvaptan. In addition, to understand the effect of various V2R substitutions on the full receptor "life-cycle," we have used and further developed a bioluminescence resonance energy transfer intracellular localization assay using multiple localization markers validated with confocal microscopy. This allowed us to characterize differences in the constitutive and ligand-induced localization and trafficking profiles of the novel L312S mutation as well as for previously described V2R gain-of-function mutants (NSIAD; R137C and R137L), loss-of-function mutants (nephrogenic diabetes insipidus; R137H, R181C, and M311V), and a putative silent V266A V2R polymorphism. In doing so, we describe differences in trafficking between unique V2R substitutions, even at the same amino acid position, therefore highlighting the value of full and thorough characterization of receptor function beyond simple signaling pathway analysis.
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Affiliation(s)
- Anatoly Tiulpakov
- Harry Perkins Institute of Medical Research (C.W.W., R.S.A., H.B.S., R.M.S., J.I.H., K.D.G.P.), QEII Medical Centre; Centre for Medical Research (C.W.W., R.S.A., H.B.S., R.M.S., J.I.H., K.D.G.P.) and School of Surgery (A.S.C., N.J.P.), The University of Western Australia; and Dimerix Limited (K.D.G.P.), Nedlands, Western Australia 6009, Australia; and Department and Laboratory of Inherited Endocrine Disorders (A.T., I.D.), Endocrinology Research Centre, Moscow 117036, Russia
| | - Carl W White
- Harry Perkins Institute of Medical Research (C.W.W., R.S.A., H.B.S., R.M.S., J.I.H., K.D.G.P.), QEII Medical Centre; Centre for Medical Research (C.W.W., R.S.A., H.B.S., R.M.S., J.I.H., K.D.G.P.) and School of Surgery (A.S.C., N.J.P.), The University of Western Australia; and Dimerix Limited (K.D.G.P.), Nedlands, Western Australia 6009, Australia; and Department and Laboratory of Inherited Endocrine Disorders (A.T., I.D.), Endocrinology Research Centre, Moscow 117036, Russia
| | - Rekhati S Abhayawardana
- Harry Perkins Institute of Medical Research (C.W.W., R.S.A., H.B.S., R.M.S., J.I.H., K.D.G.P.), QEII Medical Centre; Centre for Medical Research (C.W.W., R.S.A., H.B.S., R.M.S., J.I.H., K.D.G.P.) and School of Surgery (A.S.C., N.J.P.), The University of Western Australia; and Dimerix Limited (K.D.G.P.), Nedlands, Western Australia 6009, Australia; and Department and Laboratory of Inherited Endocrine Disorders (A.T., I.D.), Endocrinology Research Centre, Moscow 117036, Russia
| | - Heng B See
- Harry Perkins Institute of Medical Research (C.W.W., R.S.A., H.B.S., R.M.S., J.I.H., K.D.G.P.), QEII Medical Centre; Centre for Medical Research (C.W.W., R.S.A., H.B.S., R.M.S., J.I.H., K.D.G.P.) and School of Surgery (A.S.C., N.J.P.), The University of Western Australia; and Dimerix Limited (K.D.G.P.), Nedlands, Western Australia 6009, Australia; and Department and Laboratory of Inherited Endocrine Disorders (A.T., I.D.), Endocrinology Research Centre, Moscow 117036, Russia
| | - Audrey S Chan
- Harry Perkins Institute of Medical Research (C.W.W., R.S.A., H.B.S., R.M.S., J.I.H., K.D.G.P.), QEII Medical Centre; Centre for Medical Research (C.W.W., R.S.A., H.B.S., R.M.S., J.I.H., K.D.G.P.) and School of Surgery (A.S.C., N.J.P.), The University of Western Australia; and Dimerix Limited (K.D.G.P.), Nedlands, Western Australia 6009, Australia; and Department and Laboratory of Inherited Endocrine Disorders (A.T., I.D.), Endocrinology Research Centre, Moscow 117036, Russia
| | - Ruth M Seeber
- Harry Perkins Institute of Medical Research (C.W.W., R.S.A., H.B.S., R.M.S., J.I.H., K.D.G.P.), QEII Medical Centre; Centre for Medical Research (C.W.W., R.S.A., H.B.S., R.M.S., J.I.H., K.D.G.P.) and School of Surgery (A.S.C., N.J.P.), The University of Western Australia; and Dimerix Limited (K.D.G.P.), Nedlands, Western Australia 6009, Australia; and Department and Laboratory of Inherited Endocrine Disorders (A.T., I.D.), Endocrinology Research Centre, Moscow 117036, Russia
| | - Julian I Heng
- Harry Perkins Institute of Medical Research (C.W.W., R.S.A., H.B.S., R.M.S., J.I.H., K.D.G.P.), QEII Medical Centre; Centre for Medical Research (C.W.W., R.S.A., H.B.S., R.M.S., J.I.H., K.D.G.P.) and School of Surgery (A.S.C., N.J.P.), The University of Western Australia; and Dimerix Limited (K.D.G.P.), Nedlands, Western Australia 6009, Australia; and Department and Laboratory of Inherited Endocrine Disorders (A.T., I.D.), Endocrinology Research Centre, Moscow 117036, Russia
| | - Ivan Dedov
- Harry Perkins Institute of Medical Research (C.W.W., R.S.A., H.B.S., R.M.S., J.I.H., K.D.G.P.), QEII Medical Centre; Centre for Medical Research (C.W.W., R.S.A., H.B.S., R.M.S., J.I.H., K.D.G.P.) and School of Surgery (A.S.C., N.J.P.), The University of Western Australia; and Dimerix Limited (K.D.G.P.), Nedlands, Western Australia 6009, Australia; and Department and Laboratory of Inherited Endocrine Disorders (A.T., I.D.), Endocrinology Research Centre, Moscow 117036, Russia
| | - Nathan J Pavlos
- Harry Perkins Institute of Medical Research (C.W.W., R.S.A., H.B.S., R.M.S., J.I.H., K.D.G.P.), QEII Medical Centre; Centre for Medical Research (C.W.W., R.S.A., H.B.S., R.M.S., J.I.H., K.D.G.P.) and School of Surgery (A.S.C., N.J.P.), The University of Western Australia; and Dimerix Limited (K.D.G.P.), Nedlands, Western Australia 6009, Australia; and Department and Laboratory of Inherited Endocrine Disorders (A.T., I.D.), Endocrinology Research Centre, Moscow 117036, Russia
| | - Kevin D G Pfleger
- Harry Perkins Institute of Medical Research (C.W.W., R.S.A., H.B.S., R.M.S., J.I.H., K.D.G.P.), QEII Medical Centre; Centre for Medical Research (C.W.W., R.S.A., H.B.S., R.M.S., J.I.H., K.D.G.P.) and School of Surgery (A.S.C., N.J.P.), The University of Western Australia; and Dimerix Limited (K.D.G.P.), Nedlands, Western Australia 6009, Australia; and Department and Laboratory of Inherited Endocrine Disorders (A.T., I.D.), Endocrinology Research Centre, Moscow 117036, Russia
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Brachet C, Vandergheynst F, Heinrichs C. Nephrogenic Syndrome of Inappropriate Antidiuresis in a Female Neonate: Review of the Clinical Presentation in Females. Horm Res Paediatr 2016; 84:65-7. [PMID: 25925274 DOI: 10.1159/000381586] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Accepted: 03/04/2015] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Nephrogenic syndrome of inappropriate antidiuresis (NSIAD) is a rare X-linked disease due to gain-of-function mutations in the AVP V2 receptor gene. Hemizygous males present with recurrent episodes of severe hyponatremia in infancy. Heterozygous females are usually asymptomatic. CASE REPORT We report on a 23-day-old female neonate, born at term with 3,260 g that presented with recurrent hyponatremia (Na between 124 and 134 mmol/l) due to NSIAD. She was a heterozygous carrier of the c.409 C>T mutation in the AVPR2 gene. CONCLUSIONS This is the first report of a female neonate presenting with hyponatremia due to NSIAD. The diagnosis of NSIAD should not be limited to male infants and should also be considered in female infants with the clinical picture of inappropriate antidiuresis.
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Affiliation(s)
- Cécile Brachet
- Endocrinology Unit, Department of Pediatrics, Hôpital Universitaire des Enfants Reine Fabiola, Université Libre de Bruxelles, Brussels, Belgium
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Rosner MH, Perazella MA, Choi MJ. American Society of Nephrology Quiz and Questionnaire 2015: Electrolytes and Acid-Base Disorders. Clin J Am Soc Nephrol 2016; 11:735-44. [PMID: 26825098 DOI: 10.2215/cjn.12801215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The Nephrology Quiz and Questionnaire remains an extremely popular session for attendees of the annual Kidney Week meeting of the American Society of Nephrology. During the 2015 meeting the conference hall was once again overflowing with eager quiz participants. Topics covered by the experts included electrolyte and acid-base disorders, glomerular disease, end-stage renal disease and dialysis, and kidney transplantation. Complex cases representing each of these categories together with single-best-answer questions were prepared and submitted by the panel of experts. Before the meeting, training program directors of nephrology fellowship programs and nephrology fellows in the United States answered the questions through an internet-based questionnaire. During the live session members of the audience tested their knowledge and judgment on the same series of case-oriented questions in a quiz. The audience compared their answers in real time using a cell-phone app containing the answers of the nephrology fellows and training program directors. The results of the online questionnaire were displayed, and then the quiz answers were discussed. As always, the audience, lecturers, and moderators enjoyed this highly educational session. This article recapitulates the session and reproduces selected content of educational value for theClinical Journal of the American Society of Nephrologyreaders. Enjoy the clinical cases and expert discussions.
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Affiliation(s)
- Mitchell H Rosner
- Division of Nephrology, University of Virginia Health System, Charlottesville, Virginia;
| | - Mark A Perazella
- Section of Nephrology, Yale University School of Medicine, New Haven, Connecticut; and
| | - Michael J Choi
- Division of Nephrology, Johns Hopkins University, Baltimore, Maryland
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32
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Mutation in the V2 vasopressin receptor gene, AVPR2, causes nephrogenic syndrome of inappropriate diuresis. Kidney Int 2015; 88:1070-8. [PMID: 26131744 DOI: 10.1038/ki.2015.181] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Revised: 04/15/2015] [Accepted: 04/16/2015] [Indexed: 12/23/2022]
Abstract
Nephrogenic syndrome of inappropriate antidiuresis (NSIAD) is a recently discovered rare disease caused by gain-of-function mutations of the V2 vasopressin receptor gene, AVPR2. To date, mutations of Phe229 and Arg137 have been identified as gain-of-function in the V2 vasopressin receptor (V2R). These receptor mutations lead to hyponatremia, which may lead to clinical symptoms in infants. Here we present a newly identified I130N substitution in exon 2 of the V2R gene in a family, causing NSIAD. This I130N mutation resulted in constitutive activity of the V2R with constitutive cyclic adenosine monophosphate (cAMP) generation in HEK293 cells. This basal activity could be blocked by the inverse agonist tolvaptan and arginine-vasopressin stimulation enhanced the cAMP production of I130N-V2R. The mutation causes a biased receptor conformation as the basal cAMP generation activity of I130N does not lead to interaction with β-arrestin. The constitutive activity of the mutant receptor caused constitutive dynamin-dependent and β-arrestin-independent internalization. The inhibition of basal internalization using dominant-negative dynamin resulted in an increased cell surface expression. In contrast to the constitutive internalization, agonist-induced endocytosis was β-arrestin dependent. Thus, tolvaptan could be used for treatment of hyponatremia in patients with NSIAD who carry the I130N-V2R mutation.
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Thompson MD, Hendy GN, Percy ME, Bichet DG, Cole DEC. G protein-coupled receptor mutations and human genetic disease. Methods Mol Biol 2015; 1175:153-87. [PMID: 25150870 DOI: 10.1007/978-1-4939-0956-8_8] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Genetic variations in G protein-coupled receptor genes (GPCRs) disrupt GPCR function in a wide variety of human genetic diseases. In vitro strategies and animal models have been used to identify the molecular pathologies underlying naturally occurring GPCR mutations. Inactive, overactive, or constitutively active receptors have been identified that result in pathology. These receptor variants may alter ligand binding, G protein coupling, receptor desensitization and receptor recycling. Receptor systems discussed include rhodopsin, thyrotropin, parathyroid hormone, melanocortin, follicle-stimulating hormone (FSH), luteinizing hormone, gonadotropin-releasing hormone (GNRHR), adrenocorticotropic hormone, vasopressin, endothelin-β, purinergic, and the G protein associated with asthma (GPRA or neuropeptide S receptor 1 (NPSR1)). The role of activating and inactivating calcium-sensing receptor (CaSR) mutations is discussed in detail with respect to familial hypocalciuric hypercalcemia (FHH) and autosomal dominant hypocalemia (ADH). The CASR mutations have been associated with epilepsy. Diseases caused by the genetic disruption of GPCR functions are discussed in the context of their potential to be selectively targeted by drugs that rescue altered receptors. Examples of drugs developed as a result of targeting GPCRs mutated in disease include: calcimimetics and calcilytics, therapeutics targeting melanocortin receptors in obesity, interventions that alter GNRHR loss from the cell surface in idiopathic hypogonadotropic hypogonadism and novel drugs that might rescue the P2RY12 receptor congenital bleeding phenotype. De-orphanization projects have identified novel disease-associated receptors, such as NPSR1 and GPR35. The identification of variants in these receptors provides genetic reagents useful in drug screens. Discussion of the variety of GPCRs that are disrupted in monogenic Mendelian disorders provides the basis for examining the significance of common pharmacogenetic variants.
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Affiliation(s)
- Miles D Thompson
- Department of Pharmacology, University of Toronto, 1 King's College Circle, Toronto, ON, Canada, M5S 1A8,
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Morin D. [Vasopressin V2 receptor-related pathologies: congenital nephrogenic diabetes insipidus and nephrogenic syndrome of inappropiate antidiuresis]. Nephrol Ther 2014; 10:538-46. [PMID: 25449762 DOI: 10.1016/j.nephro.2014.09.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Congenital nephrogenic diabetes insipidus is a rare hereditary disease with mainly an X-linked inheritance (90% of the cases) but there are also autosomal recessive and dominant forms. Congenital nephrogenic diabetes insipidus is characterized by a resistance of the renal collecting duct to the action of the arginine vasopressin hormone responsible for the inability of the kidney to concentrate urine. The X-linked form is due to inactivating mutations of the vasopressin 2 receptor gene leading to a loss of function of the mutated receptors. Affected males are often symptomatic in the neonatal period with a lack of weight gain, dehydration and hypernatremia but mild phenotypes may also occur. Females carrying the mutation may be asymptomatic but, sometimes, severe polyuria is found due to the random X chromosome inactivation. The autosomal recessive and dominant forms, occurring in both genders, are linked to mutations in the aquaporin-2 gene. The treatment remains difficult, especially in infants, and is based on a low osmotic diet with increased water intake and the use of thiazides and indomethacin. The main goal is to avoid hypernatremic episodes and maintain a good hydration state. Potentially, specific treatment, in some cases of X-linked congenital nephrogenic diabetes insipidus, with pharmacological chaperones such as non-peptide vasopressin-2 receptor antagonists will be available in the future. Conversely, the nephrogenic syndrome of inappropriate antidiuresis (NSIAD) is linked to a constitutive activation of the V(2)-receptor due to activating mutations with clinical and biological features of inappropriate antidiuresis but with low or undetectable plasma arginine vasopressin hormone levels.
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Affiliation(s)
- Denis Morin
- Département de pédiatrie, hôpital Arnaud-de-Villeneuve, CHU de Montpellier, 371, avenue du Doyen-Gaston-Giraud, 34295 Montpellier cedex 5, France; Centre de référence des maladies rares du Sud-Ouest, 371, avenue du Doyen-Gaston-Giraud, 34295 Montpellier cedex 5, France; CNRS UMR 5203, Inserm U661, 141, rue de la Cardonille, 34094 Montpellier cedex 5, France; Université Montpellier I, 34295 Montpellier cedex 5, France.
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Juul KV, Bichet DG, Nielsen S, Nørgaard JP. The physiological and pathophysiological functions of renal and extrarenal vasopressin V2 receptors. Am J Physiol Renal Physiol 2014; 306:F931-40. [PMID: 24598801 DOI: 10.1152/ajprenal.00604.2013] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The arginine vasopressin (AVP) type 2 receptor (V2R) is unique among AVP receptor subtypes in signaling through cAMP. Its key function is in the kidneys, facilitating the urine concentrating mechanism through the AVP/V2 type receptor/aquaporin 2 system in the medullary and cortical collecting ducts. Recent clinical and research observations strongly support the existence of an extrarenal V2R. The clinical importance of the extrarenal V2R spans widely from stimulation of coagulation factor in the endothelium to as yet untested potential therapeutic targets. These include V2R-regulated membranous fluid turnover in the inner ear, V2R-regulated mitogensis and apoptosis in certain tumor tissues, and numerous other cell types where the physiological role of V2Rs still requires further research. Here, we review current evidence on the physiological and pathophysiological functions of renal and extrarenal V2Rs. These functions of V2R are important, not only in rare diseases with loss or gain of function of V2R but also in relation to the recent use of nonpeptide V2R antagonists to treat hyponatremia and possibly retard the growth of cysts and development of renal failure in autosomal dominant polycystic kidney disease. The main functions of V2R in principal cells of the collecting duct are water, salt, and urea transport by modifying the trafficking of aquaporin 2, epithelial Na(+) channels, and urea transporters and vasodilation and stimulation of coagulation factor properties, mainly seen with pharmacological doses of 1-desamino-8-D-AVP. The AVPR2 gene is located on the X chromosome, in a region with high probability of escape from inactivation; this may lead to phenotypic sex differences, with females expressing higher levels of transcript than males.
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Affiliation(s)
- Kristian Vinter Juul
- Medical Science Urology, Ferring Pharmaceuticals, 11 Kay Fiskers Plads, Copenhagen S DK-2300, Denmark.
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SuperBiHelix method for predicting the pleiotropic ensemble of G-protein-coupled receptor conformations. Proc Natl Acad Sci U S A 2013; 111:E72-8. [PMID: 24344284 DOI: 10.1073/pnas.1321233111] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
There is overwhelming evidence that G-protein-coupled receptors (GPCRs) exhibit several distinct low-energy conformations, each of which might favor binding to different ligands and/or lead to different downstream functions. Understanding the function of such proteins requires knowledge of the ensemble of low-energy configurations that might play a role in this pleiotropic functionality. We earlier reported the BiHelix method for efficiently sampling the (12)(7) = 35 million conformations resulting from 30° rotations about the axis (η) of all seven transmembrane helices (TMHs), showing that the experimental structure is reliably selected as the best conformation from this ensemble. However, various GPCRs differ sufficiently in the tilts of the TMHs that this method need not predict the optimum conformation starting from any other template. In this paper, we introduce the SuperBiHelix method in which the tilt angles (θ, ϕ) are optimized simultaneously with rotations (η) efficiently enough that it is practical and sufficient to sample (5 × 3 × 5)(7) = 13 trillion configurations. This method can correctly identify the optimum structure of a GPCR starting with the template from a different GPCR. We have validated this method by predicting known crystal structure conformations starting from the template of a different protein structure. We find that the SuperBiHelix conformational ensemble includes the higher energy conformations associated with the active protein in addition to those associated with the more stable inactive protein. This methodology was then applied to design and experimentally confirm structures of three mutants of the CB1 cannabinoid receptor associated with different functions.
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Kortenoeven MLA, Fenton RA. Renal aquaporins and water balance disorders. Biochim Biophys Acta Gen Subj 2013; 1840:1533-49. [PMID: 24342488 DOI: 10.1016/j.bbagen.2013.12.002] [Citation(s) in RCA: 100] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Revised: 11/26/2013] [Accepted: 12/09/2013] [Indexed: 12/17/2022]
Abstract
BACKGROUND Aquaporins (AQPs) are a family of proteins that can act as water channels. Regulation of AQPs is critical to osmoregulation and the maintenance of body water homeostasis. Eight AQPs are expressed in the kidney of which five have been shown to play a role in body water balance; AQP1, AQP2, AQP3, AQP4 and AQP7. AQP2 in particular is regulated by vasopressin. SCOPE OF REVIEW This review summarizes our current knowledge of the underlying mechanisms of various water balance disorders and their treatment strategies. MAJOR CONCLUSIONS Dysfunctions of AQPs are involved in disorders associated with disturbed water homeostasis. Hyponatremia with increased AQP levels can be caused by diseases with low effective circulating blood volume, such as congestive heart failure, or osmoregulation disorders such as the syndrome of inappropriate secretion of antidiuretic hormone. Treatment consists of fluid restriction, demeclocycline and vasopressin type-2 receptor antagonists. Decreased AQP levels can lead to diabetes insipidus (DI), characterized by polyuria and polydipsia. In central DI, vasopressin production is impaired, while in gestational DI, levels of the vasopressin-degrading enzyme vasopressinase are abnormally increased. Treatment consists of the vasopressin analogue dDAVP. Nephrogenic DI is caused by the inability of the kidney to respond to vasopressin and can be congenital, but is most commonly acquired, usually due to lithium therapy. Treatment consists of sufficient fluid supply, low-solute diet and diuretics. GENERAL SIGNIFICANCE In recent years, our understanding of the underlying mechanisms of water balance disorders has increased enormously, which has opened up several possible new treatment strategies. This article is part of a Special Issue entitled Aquaporins.
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Affiliation(s)
- Marleen L A Kortenoeven
- Department of Biomedicine, Aarhus University, Aarhus, Denmark; Center for Interactions of Proteins in Epithelial Transport (InterPrET), Aarhus University, Aarhus, Denmark.
| | - Robert A Fenton
- Department of Biomedicine, Aarhus University, Aarhus, Denmark; Center for Interactions of Proteins in Epithelial Transport (InterPrET), Aarhus University, Aarhus, Denmark.
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Armstrong SP, Seeber RM, Ayoub MA, Feldman BJ, Pfleger KDG. Characterization of three vasopressin receptor 2 variants: an apparent polymorphism (V266A) and two loss-of-function mutations (R181C and M311V). PLoS One 2013; 8:e65885. [PMID: 23762448 PMCID: PMC3675069 DOI: 10.1371/journal.pone.0065885] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Accepted: 04/30/2013] [Indexed: 02/01/2023] Open
Abstract
Arginine vasopressin (AVP) is released from the posterior pituitary and controls water homeostasis. AVP binding to vasopressin V2 receptors (V2Rs) located on kidney collecting duct epithelial cells triggers activation of Gs proteins, leading to increased cAMP levels, trafficking of aquaporin-2 water channels, and consequent increased water permeability and antidiuresis. Typically, loss-of-function V2R mutations cause nephrogenic diabetes insipidus (NDI), whereas gain-of-function mutations cause nephrogenic syndrome of inappropriate antidiuresis (NSIAD). Here we provide further characterization of two mutant V2Rs, R181C and M311V, reported to cause complete and partial NDI respectively, together with a V266A variant, in a patient diagnosed with NSIAD. Our data in HEK293FT cells revealed that for cAMP accumulation, AVP was about 500- or 30-fold less potent at the R181C and M311V mutants than at the wild-type receptor respectively (and about 4000- and 60-fold in COS7 cells respectively). However, in contrast to wild type V2R, the R181C mutant failed to increase inositol phosphate production, while with the M311V mutant, AVP exhibited only partial agonism in addition to a 37-fold potency decrease. Similar responses were detected in a BRET assay for β-arrestin recruitment, with the R181C receptor unresponsive to AVP, and partial agonism with a 23-fold decrease in potency observed with M311V in both HEK293FT and COS7 cells. Notably, the V266A V2R appeared functionally identical to the wild-type receptor in all assays tested, including cAMP and inositol phosphate accumulation, β-arrestin interaction, and in a BRET assay of receptor ubiquitination. Each receptor was expressed at comparable levels. Hence, the M311V V2R retains greater activity than the R181C mutant, consistent with the milder phenotype of NDI associated with this mutant. Notably, the R181C mutant appears to be a Gs protein-biased receptor incapable of signaling to inositol phosphate or recruiting β-arrestin. The etiology of NSIAD in the patient with V266A V2R remains unknown.
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MESH Headings
- Animals
- Aquaporin 2/genetics
- Aquaporin 2/metabolism
- Arginine Vasopressin/metabolism
- Arrestins/genetics
- Arrestins/metabolism
- COS Cells
- Chlorocebus aethiops
- Cyclic AMP/metabolism
- Diabetes Insipidus, Nephrogenic/genetics
- Diabetes Insipidus, Nephrogenic/metabolism
- Diabetes Insipidus, Nephrogenic/pathology
- GTP-Binding Protein alpha Subunits, Gs/genetics
- GTP-Binding Protein alpha Subunits, Gs/metabolism
- Gene Expression Regulation
- Genetic Diseases, X-Linked/genetics
- Genetic Diseases, X-Linked/metabolism
- Genetic Diseases, X-Linked/pathology
- HEK293 Cells
- Humans
- Inappropriate ADH Syndrome/genetics
- Inappropriate ADH Syndrome/metabolism
- Inappropriate ADH Syndrome/pathology
- Inositol Phosphates/metabolism
- Mutation
- Polymorphism, Genetic
- Receptors, Vasopressin/genetics
- Receptors, Vasopressin/metabolism
- Signal Transduction
- beta-Arrestins
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Affiliation(s)
- Stephen P. Armstrong
- Laboratory for Molecular Endocrinology-G Protein-Coupled Receptors, Western Australian Institute for Medical Research and Centre for Medical Research, The University of Western Australia, Nedlands, Perth, Western Australia, Australia
| | - Ruth M. Seeber
- Laboratory for Molecular Endocrinology-G Protein-Coupled Receptors, Western Australian Institute for Medical Research and Centre for Medical Research, The University of Western Australia, Nedlands, Perth, Western Australia, Australia
| | - Mohammed Akli Ayoub
- Laboratory for Molecular Endocrinology-G Protein-Coupled Receptors, Western Australian Institute for Medical Research and Centre for Medical Research, The University of Western Australia, Nedlands, Perth, Western Australia, Australia
- Protein Research Chair - Department of Biochemistry, College of Science, King Saud University, Riyadh, Kingdom of Saudi Arabia
| | - Brian J. Feldman
- Pediatric Endocrinology, Department of Pediatrics, Stanford University, Stanford, California, United States of America
| | - Kevin D. G. Pfleger
- Laboratory for Molecular Endocrinology-G Protein-Coupled Receptors, Western Australian Institute for Medical Research and Centre for Medical Research, The University of Western Australia, Nedlands, Perth, Western Australia, Australia
- * E-mail:
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