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Yu ASL, Curry JN. Paracellular Transport and Renal Tubule Calcium Handling: Emerging Roles in Kidney Stone Disease. J Am Soc Nephrol 2024:00001751-990000000-00411. [PMID: 39207856 DOI: 10.1681/asn.0000000506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2024] [Accepted: 08/26/2024] [Indexed: 09/04/2024] Open
Abstract
The kidney plays a major role in maintenance of serum calcium concentration, which must be kept within a narrow range to avoid disruption of numerous physiologic processes that depend critically on the level of extracellular calcium, including cell signaling, bone structure, and muscle and nerve function. This defense of systemic calcium homeostasis comes, however, at the expense of the dumping of calcium into the kidney tissue and urine. Because of the large size and multivalency of the calcium ion, its salts are the least soluble among all the major cations in the body. The potential pathologic consequences of this are nephrocalcinosis and kidney stone disease. In this review, we discuss recent advances that have highlighted critical roles for the proximal tubule and thick ascending limb in renal calcium reabsorption, elucidated the molecular mechanisms for paracellular transport in these segments, and implicated disturbances in these processes in human disease.
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Affiliation(s)
- Alan S L Yu
- Division of Nephrology and Hypertension, Department of Internal Medicine, Jared Grantham Kidney Institute, University of Kansas Medical Center, Kansas City, Kansas
| | - Joshua N Curry
- Division of Nephrology, Oregon Health Sciences University, Portland, Oregon
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2
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Culver SA, Suleman N, Kavuru V, Siragy HM. Renal Hypokalemia: An Endocrine Perspective. J Clin Endocrinol Metab 2024; 109:1694-1706. [PMID: 38546505 DOI: 10.1210/clinem/dgae201] [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: 11/20/2023] [Indexed: 06/18/2024]
Abstract
The majority of disorders that cause renal potassium wasting present with abnormalities in adrenal hormone secretion. While these findings frequently lead patients to seek endocrine evaluation, clinicians often struggle to accurately diagnose these conditions, delaying treatment and adversely impacting patient care. At the same time, growing insight into the genetic and molecular basis of these disorders continues to improve their diagnosis and management. In this review, we outline a practical integrated approach to the evaluation of renal hypokalemia syndromes that are seen in endocrine practice while highlighting recent advances in understanding of the genetics and pathophysiology behind them.
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Affiliation(s)
- Silas A Culver
- Division of Endocrinology, Department of Medicine, University of Virginia Health System, Charlottesville, VA 22908, USA
| | - Nawar Suleman
- Division of Endocrinology, Department of Medicine, University of Virginia Health System, Charlottesville, VA 22908, USA
| | - Varun Kavuru
- Department of Medicine, University of Virginia Health System, Charlottesville, VA 22908, USA
| | - Helmy M Siragy
- Division of Endocrinology, Department of Medicine, University of Virginia Health System, Charlottesville, VA 22908, USA
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3
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Koo KC, Halawani A, Wong VK, Lange D, Chew BH. Monogenic features of urolithiasis: A comprehensive review. Asian J Urol 2024; 11:169-179. [PMID: 38680588 PMCID: PMC11053333 DOI: 10.1016/j.ajur.2023.03.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Accepted: 03/28/2023] [Indexed: 05/01/2024] Open
Abstract
Objective Urolithiasis formation has been attributed to environmental and dietary factors. However, evidence is accumulating that genetic background can contribute to urolithiasis formation. Advancements in the identification of monogenic causes using high-throughput sequencing technologies have shown that urolithiasis has a strong heritable component. Methods This review describes monogenic factors implicated in a genetic predisposition to urolithiasis. Peer-reviewed journals were evaluated by a PubMed search until July 2023 to summarize disorders associated with monogenic traits, and discuss clinical implications of identification of patients genetically susceptible to urolithiasis formation. Results Given that more than 80% of urolithiases cases are associated with calcium accumulation, studies have focused mainly on monogenetic contributors to hypercalciuric urolithiases, leading to the identification of receptors, channels, and transporters involved in the regulation of calcium renal tubular reabsorption. Nevertheless, available candidate genes and linkage methods have a low resolution for evaluation of the effects of genetic components versus those of environmental, dietary, and hormonal factors, and genotypes remain undetermined in the majority of urolithiasis formers. Conclusion The pathophysiology underlying urolithiasis formation is complex and multifactorial, but evidence strongly suggests the existence of numerous monogenic causes of urolithiasis in humans.
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Affiliation(s)
- Kyo Chul Koo
- Department of Urology, Yonsei University College of Medicine, Seoul, Republic of Korea
| | | | - Victor K.F. Wong
- Department of Urological Sciences, University of British Columbia, Stone Centre at Vancouver General Hospital, Vancouver, British Columbia, Canada
| | - Dirk Lange
- Department of Urological Sciences, University of British Columbia, Stone Centre at Vancouver General Hospital, Vancouver, British Columbia, Canada
| | - Ben H. Chew
- Department of Urological Sciences, University of British Columbia, Stone Centre at Vancouver General Hospital, Vancouver, British Columbia, Canada
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Saglia C, Arruga F, Scolari C, Kalantari S, Albanese S, Bracciamà V, Corso Faini A, Brach Del Prever G, Luca M, Romeo C, Mioli F, Migliorero M, Tessaris D, Carli D, Amoroso A, Vaisitti T, De Sanctis L, Deaglio S. Functional evaluation of a novel nonsense variant of the calcium-sensing receptor gene leading to hypocalcemia. Eur J Endocrinol 2024; 190:296-306. [PMID: 38561929 DOI: 10.1093/ejendo/lvae035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Revised: 03/06/2024] [Accepted: 03/08/2024] [Indexed: 04/04/2024]
Abstract
OBJECTIVE The calcium-sensing receptor (CASR) gene encodes a G protein-coupled receptor crucial for calcium homeostasis. Gain-of-function CASR variants result in hypocalcemia, while loss-of-function variants lead to hypercalcemia. This study aims to assess the functional consequences of the novel nonsense CASR variant [c.2897_2898insCTGA, p.(Gln967*) (Q967*)] identified in adolescent patient with chronic hypocalcemia, a phenotype expected for a gain-of-function variants. DESIGN AND METHODS To functionally characterize the Q967* mutant receptor, both wild-type (WT) and mutant CASR were transiently transfected into HEK293T cells and calcium-sensing receptor (CaSR) protein expression and functions were comparatively evaluated using multiple read-outs. RESULTS Western blot analysis revealed that the CaSR mutant protein displayed a lower molecular weight compared with the WT, consistent with the loss of the last 122 amino acids in the intracellular domain. Mitogen-activated protein kinase activation and serum responsive element luciferase assays demonstrated that the mutant receptor had higher baseline activity than the WT. Extracellular-signal-regulated kinase/c-Jun N-terminal kinase phosphorylation, however, remained consistently high in the mutant, without significant modulations following exposure to increasing extracellular calcium (Ca2+o) levels, suggesting that the mutant receptor is more sensitive to Ca2+o compared with the WT. CONCLUSIONS This study provides functional validation of the pathogenicity of a novel nonsense CASR variant, resulting in an abnormally hyperfunctioning protein consistent with the patient's phenotype. Functional analyses indicate that mutant receptor is constitutively active and poorly sensitive to increasing concentrations of extracellular calcium, suggesting that the cytoplasmic tail may contain elements regulating signal transduction.
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Affiliation(s)
- Claudia Saglia
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
| | - Francesca Arruga
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
| | - Caterina Scolari
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
| | - Silvia Kalantari
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
| | - Serena Albanese
- Department of Public Health and Pediatric Sciences, University of Torino, Torino 10126, Italy
- Pediatric Endocrinology, Regina Margherita Childrens' Hospital, Torino 10126, Italy
| | - Valeria Bracciamà
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
| | - Angelo Corso Faini
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
| | - Giulia Brach Del Prever
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
| | - Maria Luca
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
| | - Carmelo Romeo
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
| | - Fiorenza Mioli
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
| | | | - Daniele Tessaris
- Department of Public Health and Pediatric Sciences, University of Torino, Torino 10126, Italy
- Pediatric Endocrinology, Regina Margherita Childrens' Hospital, Torino 10126, Italy
| | - Diana Carli
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
| | - Antonio Amoroso
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
| | - Tiziana Vaisitti
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
| | - Luisa De Sanctis
- Department of Public Health and Pediatric Sciences, University of Torino, Torino 10126, Italy
- Pediatric Endocrinology, Regina Margherita Childrens' Hospital, Torino 10126, Italy
| | - Silvia Deaglio
- Department of Medical Sciences, University of Turin, Turin 10126, Italy
- Immunogenetics and Transplant Biology Unit, Città della Salute e della Scienza Hospital, Turin 10126, Italy
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Gefen AM, Zaritsky JJ. Review of childhood genetic nephrolithiasis and nephrocalcinosis. Front Genet 2024; 15:1381174. [PMID: 38606357 PMCID: PMC11007102 DOI: 10.3389/fgene.2024.1381174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2024] [Accepted: 03/04/2024] [Indexed: 04/13/2024] Open
Abstract
Nephrolithiasis (NL) is a common condition worldwide. The incidence of NL and nephrocalcinosis (NC) has been increasing, along with their associated morbidity and economic burden. The etiology of NL and NC is multifactorial and includes both environmental components and genetic components, with multiple studies showing high heritability. Causative gene variants have been detected in up to 32% of children with NL and NC. Children with NL and NC are genotypically heterogenous, but often phenotypically relatively homogenous, and there are subsequently little data on the predictors of genetic childhood NL and NC. Most genetic diseases associated with NL and NC are secondary to hypercalciuria, including those secondary to hypercalcemia, renal phosphate wasting, renal magnesium wasting, distal renal tubular acidosis (RTA), proximal tubulopathies, mixed or variable tubulopathies, Bartter syndrome, hyperaldosteronism and pseudohyperaldosteronism, and hyperparathyroidism and hypoparathyroidism. The remaining minority of genetic diseases associated with NL and NC are secondary to hyperoxaluria, cystinuria, hyperuricosuria, xanthinuria, other metabolic disorders, and multifactorial etiologies. Genome-wide association studies (GWAS) in adults have identified multiple polygenic traits associated with NL and NC, often involving genes that are involved in calcium, phosphorus, magnesium, and vitamin D homeostasis. Compared to adults, there is a relative paucity of studies in children with NL and NC. This review aims to focus on the genetic component of NL and NC in children.
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Affiliation(s)
- Ashley M. Gefen
- Phoenix Children’s Hospital, Department of Pediatrics, Division of Nephrology, Phoenix, AZ, United States
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Gamba G. From Fish Physiology to Human Disease: The Discovery of the NCC, NKCC2, and the Cation-Coupled Chloride Cotransporters. KIDNEY360 2024; 5:133-141. [PMID: 37968800 PMCID: PMC10833596 DOI: 10.34067/kid.0000000000000307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 10/26/2023] [Indexed: 11/17/2023]
Abstract
The renal Na-K-2Cl and Na-Cl cotransporters are the major salt reabsorption pathways in the thick ascending limb of Henle loop and the distal convoluted tubule, respectively. These transporters are the target of the loop and thiazide type diuretics extensively used in the world for the treatment of edematous states and arterial hypertension. The diuretics appeared in the market many years before the salt transport systems were discovered. The evolving of the knowledge and the cloning of the genes encoding the Na-K-2Cl and Na-Cl cotransporters were possible thanks to the study of marine species. This work presents the history of how we came to know the mechanisms for the loop and thiazide type diuretics actions, the use of marine species in the cloning process of these cotransporters and therefore in the whole solute carrier cotransproters 12 (SLC12) family of electroneutral cation chloride cotransporters, and the disease associated with each member of the family.
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Affiliation(s)
- Gerardo Gamba
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México and Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Tlalpan, Mexico City, Mexico
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Garcia-Nieto VM, Claverie-Martin F, Moraleda-Mesa T, Perdomo-Ramírez A, Fraga-Rodríguez GM, Luis-Yanes MI, Ramos-Trujillo E. Renal diseases that course with hypomagnesemia. Comments on a new hereditary hypomagnesemic tubulopathy. Nefrologia 2024; 44:23-31. [PMID: 38350738 DOI: 10.1016/j.nefroe.2024.02.003] [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: 01/26/2023] [Accepted: 02/15/2023] [Indexed: 02/15/2024] Open
Abstract
Renal diseases associated with hypomagnesemia are a complex and diverse group of tubulopathies caused by mutations in genes encoding proteins that are expressed in the thick ascending limb of the loop of Henle and in the distal convoluted tubule. In this paper, we review the initial description, the clinical expressiveness and etiology of four of the first hypomagnesemic tubulopathies described: type 3 Bartter and Gitelman diseases, Autosomal recessive hypomagnesemia with secondary hypocalcemia and Familial hypomagnesemia with hypercalciuria and nephrocalcinosis. The basic biochemical patterns observed in renal tubular hypomagnesemias and the modalities of transport and interaction that occur between the transporters involved in the reabsorption of magnesium in the distal convoluted tubule are described below. Finally, the recent report of a new renal disease with hypomagnesemia, type 2 hypomagnesemia with secondary hypocalcemia caused by reduced TRPM7 channel activity is described.
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Affiliation(s)
- Víctor M Garcia-Nieto
- Unidad de Nefrología Pediátrica, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain.
| | - Félix Claverie-Martin
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain
| | - Teresa Moraleda-Mesa
- Unidad de Nefrología Pediátrica, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain
| | - Ana Perdomo-Ramírez
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain
| | - Gloria Mª Fraga-Rodríguez
- Nefrologia Pediàtrica, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - María Isabel Luis-Yanes
- Unidad de Nefrología Pediátrica, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain
| | - Elena Ramos-Trujillo
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain; Departamento de Medicina Física y Farmacología, Facultad de Medicina, Universidad de la Laguna, Santa Cruz de Tenerife, Spain
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8
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Gamba G. Thirty years of the NaCl cotransporter: from cloning to physiology and structure. Am J Physiol Renal Physiol 2023; 325:F479-F490. [PMID: 37560773 PMCID: PMC10639029 DOI: 10.1152/ajprenal.00114.2023] [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: 05/02/2023] [Revised: 08/08/2023] [Accepted: 08/08/2023] [Indexed: 08/11/2023] Open
Abstract
The primary structure of the thiazide-sensitive NaCl cotransporter (NCC) was resolved 30 years ago by the molecular identification of the cDNA encoding this cotransporter, from the winter's flounder urinary bladder, following a functional expression strategy. This review outlines some aspects of how the knowledge about thiazide diuretics and NCC evolved, the history of the cloning process, and the expansion of the SLC12 family of electroneutral cotransporters. The diseases associated with activation or inactivation of NCC are discussed, as well as the molecular model by which the activity of NCC is regulated. The controversies in the field are discussed as well as recent publication of the three-dimensional model of NCC obtained by cryo-electron microscopy, revealing not only the amino acid residues critical for Na+ and Cl- translocation but also the residues critical for polythiazide binding to the transporter, opening the possibility for a new era in thiazide diuretic therapy.
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Affiliation(s)
- Gerardo Gamba
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
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9
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Morrison AR. Magnesium Homeostasis: Lessons from Human Genetics. Clin J Am Soc Nephrol 2023; 18:969-978. [PMID: 36723340 PMCID: PMC10356123 DOI: 10.2215/cjn.0000000000000103] [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: 01/20/2023] [Accepted: 01/20/2023] [Indexed: 02/02/2023]
Abstract
Mg 2+ , the fourth most abundant cation in the body, serves as a cofactor for about 600 cellular enzymes. One third of ingested Mg 2+ is absorbed from the gut through a saturable transcellular process and a concentration-dependent paracellular process. Absorbed Mg 2+ is excreted by the kidney and maintains serum Mg 2+ within a narrow range of 0.7-1.25 mmol/L. The reabsorption of Mg 2+ by the nephron is characterized by paracellular transport in the proximal tubule and thick ascending limb. The nature of the transport pathways in the gut epithelia and thick ascending limb has emerged from an understanding of the molecular mechanisms responsible for rare monogenetic disorders presenting with clinical hypomagnesemia. These human disorders due to loss-of-function mutations, in concert with mouse models, have led to a deeper understanding of Mg 2+ transport in the gut and renal tubule. This review focuses on the nature of the transporters and channels revealed by human and mouse genetics and how they are integrated into an understanding of human Mg 2+ physiology.
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Affiliation(s)
- Aubrey R Morrison
- Division of Nephrology, Department of Medicine and Developmental Biology, Washington University School of Medicine, St. Louis, Missouri
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10
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Teleanu RI, Sarman MA, Epure DA, Matei M, Roşca I, Roza E. Autosomal Dominant Hypocalcemia Type 1 and Neonatal Focal Seizures. CHILDREN (BASEL, SWITZERLAND) 2023; 10:1011. [PMID: 37371242 DOI: 10.3390/children10061011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 06/01/2023] [Accepted: 06/02/2023] [Indexed: 06/29/2023]
Abstract
Autosomal dominant hypocalcemia type 1 (ADH1) is a rare form of hypoparathyroidism that is characterized by gain-of-function mutations in the CASR gene, which provides instructions for producing the protein called calcium-sensing receptor (CaSR). Hypocalcemia in the neonatal period has a wide differential diagnosis. We present the case of a female newborn with genetic hypoparathyroidism (L125P mutation of CASR gene), hypocalcemia, and neonatal seizures due to the potential correlation between refractory neonatal seizures and ADH1. Neonatal seizures were previously described in patients with ADH1 but not in association with the L125P mutation of the CASR gene. Prompt diagnosis and management by a multidisciplinary and an appropriate therapeutic approach can prevent neurological and renal complications.
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Affiliation(s)
- Raluca Ioana Teleanu
- Faculty of Medicine, Clinical Neurosciences Department, Peadiatric Neurology, "Carol Davila" University of Medicine and Pharmacy, 050474 Bucharest, Romania
- Pediatric Neurology Department-"Dr. Victor Gomoiu" Children's Hospital, 022102 Bucharest, Romania
| | - Marlene Alexandra Sarman
- Faculty of Medicine, Clinical Neurosciences Department, Peadiatric Neurology, "Carol Davila" University of Medicine and Pharmacy, 050474 Bucharest, Romania
- Pediatric Neurology Department-"Dr. Victor Gomoiu" Children's Hospital, 022102 Bucharest, Romania
| | - Diana Anamaria Epure
- Pediatric Neurology Department-"Dr. Victor Gomoiu" Children's Hospital, 022102 Bucharest, Romania
| | - Margarita Matei
- Endocrinology Department-"Dr. Victor Gomoiu" Children's Hospital, 022102 Bucharest, Romania
| | - Ioana Roşca
- Faculty of Medicine, Clinical Neurosciences Department, Peadiatric Neurology, "Carol Davila" University of Medicine and Pharmacy, 050474 Bucharest, Romania
- "Prof. Panait Sarbu" Clinical Hospital, 060251 Bucharest, Romania
| | - Eugenia Roza
- Faculty of Medicine, Clinical Neurosciences Department, Peadiatric Neurology, "Carol Davila" University of Medicine and Pharmacy, 050474 Bucharest, Romania
- Pediatric Neurology Department-"Dr. Victor Gomoiu" Children's Hospital, 022102 Bucharest, Romania
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Houillier P, Lievre L, Hureaux M, Prot-Bertoye C. Mechanisms of paracellular transport of magnesium in intestinal and renal epithelia. Ann N Y Acad Sci 2023; 1521:14-31. [PMID: 36622354 DOI: 10.1111/nyas.14953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Magnesium is the fourth most abundant cation in the body. It plays a critical role in many biological processes, including the process of energy release. Paracellular transport of magnesium is mandatory for magnesium homeostasis. In addition to intestinal absorption that occurs in part across the paracellular pathway, magnesium is reabsorbed by the kidney tubule. The bulk of magnesium is reabsorbed through the paracellular pathway in the proximal tubule and the thick ascending limb of the loop of Henle. The finding that rare genetic diseases due to pathogenic variants in genes encoding specific claudins (CLDNs), proteins located at the tight junction that determine the selectivity and the permeability of the paracellular pathway, led to an awareness of their importance in magnesium homeostasis. Familial hypomagnesemia with hypercalciuria and nephrocalcinosis is caused by a loss of function of CLDN16 or CLDN19. Pathogenic CLDN10 variants cause HELIX syndrome, which is associated with a severe renal loss of sodium chloride and hypermagnesemia. The present review summarizes the current knowledge of the mechanisms and factors involved in paracellular magnesium permeability. The review also highlights some of the unresolved questions that need to be addressed.
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Affiliation(s)
- Pascal Houillier
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université Paris Cité, Paris, France
- CNRS ERL 8228 - Laboratoire de Physiologie Rénale et Tubulopathies, Paris, France
- Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Service de Physiologie, Paris, France
- Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Paris, France
- Centre de Référence des Maladies Rares du Calcium et du Phosphate, Paris, France
| | - Loïc Lievre
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université Paris Cité, Paris, France
- CNRS ERL 8228 - Laboratoire de Physiologie Rénale et Tubulopathies, Paris, France
| | - Marguerite Hureaux
- Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Paris, France
- Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Service de Génétique, Paris, France
- Paris Centre de Recherche Cardio-vasculaire, INSERM, Université Paris Cité, Paris, France
| | - Caroline Prot-Bertoye
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université Paris Cité, Paris, France
- CNRS ERL 8228 - Laboratoire de Physiologie Rénale et Tubulopathies, Paris, France
- Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Service de Physiologie, Paris, France
- Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Paris, France
- Centre de Référence des Maladies Rares du Calcium et du Phosphate, Paris, France
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12
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Guo W, Ji P, Xie Y. Genetic diagnosis and treatment of hereditary renal tubular disease with hypokalemia and alkalosis. J Nephrol 2023; 36:575-591. [PMID: 35994232 DOI: 10.1007/s40620-022-01428-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Accepted: 07/29/2022] [Indexed: 10/15/2022]
Abstract
Renal tubules play an important role in maintaining water, electrolyte, and acid-base balance. Renal tubule dysfunction can cause electrolyte disorders and acid-base imbalance. Clinically, hypokalemic renal tubular disease is the most common tubule disorder. With the development of molecular genetics and gene sequencing technology, hereditary renal tubular diseases have attracted attention, and an increasing number of pathogenic genes related to renal tubular diseases have been discovered and reported. Inherited renal tubular diseases mainly occur due to mutations in genes encoding various specific transporters or ion channels expressed on the tubular epithelial membrane, leading to dysfunctional renal tubular reabsorption, secretion, and excretion. An in-depth understanding of the molecular genetic basis of hereditary renal tubular disease will help to understand the physiological function of renal tubules, the mechanism by which the kidney maintains water, electrolyte, and acid-base balance, and the relationship between the kidney and other systems in the body. Meanwhile, understanding these diseases also improves our understanding of the pathogenesis of hypokalemia, alkalosis and other related diseases and ultimately promotes accurate diagnostics and effective disease treatment. The present review summarizes the most common hereditary renal tubular diseases (Bartter syndrome, Gitelman syndrome, EAST syndrome and Liddle syndrome) characterized by hypokalemia and alkalosis. Further detailed explanations are provided for pathogenic genes and functional proteins, clinical manifestations, intrinsic relationship between genotype and clinical phenotype, diagnostic clues, differential diagnosis, and treatment strategies for these diseases.
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Affiliation(s)
- Wenkai Guo
- Department of Nephrology, First Medical Center of Chinese PLA General Hospital, Chinese PLA Institute of Nephrology, State Key Laboratory of Kidney Diseases, National Clinical Research Center for Kidney Diseases, Beijing, 100853, People's Republic of China
- School of Medicine, Nankai University, Tianjin, 300071, People's Republic of China
| | - Pengcheng Ji
- Department of Nephrology, First Medical Center of Chinese PLA General Hospital, Chinese PLA Institute of Nephrology, State Key Laboratory of Kidney Diseases, National Clinical Research Center for Kidney Diseases, Beijing, 100853, People's Republic of China
| | - Yuansheng Xie
- Department of Nephrology, First Medical Center of Chinese PLA General Hospital, Chinese PLA Institute of Nephrology, State Key Laboratory of Kidney Diseases, National Clinical Research Center for Kidney Diseases, Beijing, 100853, People's Republic of China.
- School of Medicine, Nankai University, Tianjin, 300071, People's Republic of China.
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13
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Pathophysiologic approach in genetic hypokalemia: An update. ANNALES D'ENDOCRINOLOGIE 2023; 84:298-307. [PMID: 36639120 DOI: 10.1016/j.ando.2022.11.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 11/30/2022] [Indexed: 01/12/2023]
Abstract
The pathophysiology of genetic hypokalemia is close to that of non-genetic hypokalemia. New molecular pathways physiologically involved in renal and extrarenal potassium homeostasis have been highlighted. A physiological approach to diagnosis is illustrated here, with 6 cases. Mechanisms generating and sustaining of hypokalemia are discussed. After excluding acute shift of extracellular potassium to the intracellular compartment, related to hypokalemic periodic paralysis, inappropriate kaliuresis (>40mmol/24h) concomitant to hypokalemia indicates renal potassium wasting. Clinical analysis distinguishes hypertension-associated hypokalemia, due to hypermineralocorticism or related disorders. Genetic hypertensive hypokalemia is rare. It includes familial hyperaldosteronism, Liddle syndrome, apparent mineralocorticoid excess,11beta hydroxylase deficiency and Geller syndrome. In case of normo- or hypo-tensive hypokalemia, two etiologies are to be considered: chloride depletion or salt-wasting tubulopathy. Diarrhea chlorea is a rare disease responsible for intestinal chloride depletion. Due to the severity of hypokalemic metabolic alkalosis, this disease can be misdiagnosed as pseudo-Bartter syndrome. Gitelman syndrome is the most frequent cause of genetic hypokalemia. It typically associates renal sodium and potassium wasting, hypomagnesemia, conserved chloride excretion (>40mmol/24h), and low-range calcium excretion (urinary Ca/creatinine ratio<0.20mmol/mmol). Systematic analysis of hydroelectrolytic disorder and dynamic hormonal investigation optimizes indications for and orientation of genotyping of hereditary salt-losing tubulopathy.
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14
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Mannstadt M, Cianferotti L, Gafni RI, Giusti F, Kemp EH, Koch CA, Roszko KL, Yao L, Guyatt GH, Thakker RV, Xia W, Brandi ML. Hypoparathyroidism: Genetics and Diagnosis. J Bone Miner Res 2022; 37:2615-2629. [PMID: 36375809 DOI: 10.1002/jbmr.4667] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 07/22/2022] [Accepted: 07/31/2022] [Indexed: 01/05/2023]
Abstract
This narrative report summarizes diagnostic criteria for hypoparathyroidism and describes the clinical presentation and underlying genetic causes of the nonsurgical forms. We conducted a comprehensive literature search from January 2000 to January 2021 and included landmark articles before 2000, presenting a comprehensive update of these topics and suggesting a research agenda to improve diagnosis and, eventually, the prognosis of the disease. Hypoparathyroidism, which is characterized by insufficient secretion of parathyroid hormone (PTH) leading to hypocalcemia, is diagnosed on biochemical grounds. Low albumin-adjusted calcium or ionized calcium with concurrent inappropriately low serum PTH concentration are the hallmarks of the disease. In this review, we discuss the characteristics and pitfalls in measuring calcium and PTH. We also undertook a systematic review addressing the utility of measuring calcium and PTH within 24 hours after total thyroidectomy to predict long-term hypoparathyroidism. A summary of the findings is presented here; results of the detailed systematic review are published separately in this issue of JBMR. Several genetic disorders can present with hypoparathyroidism, either as an isolated disease or as part of a syndrome. A positive family history and, in the case of complex diseases, characteristic comorbidities raise the clinical suspicion of a genetic disorder. In addition to these disorders' phenotypic characteristics, which include autoimmune diseases, we discuss approaches for the genetic diagnosis. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Michael Mannstadt
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Luisella Cianferotti
- Bone Metabolic Diseases Unit, Department of Experimental and Clinical Biomedical Sciences, University of Florence, Florence, Italy
| | - Rachel I Gafni
- National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | | | | | - Christian A Koch
- Department of Medicine/Endocrinology, Fox Chase Cancer Center, Philadelphia, PA, USA.,Department of Medicine/Endocrinology, The University of Tennessee Health Science Center, Memphis, TN, USA
| | - Kelly L Roszko
- National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Liam Yao
- Department of Health Research Methods, Evidence, and Impact, and Department of Medicine, McMaster University, Hamilton, Canada
| | - Gordon H Guyatt
- Department of Health Research Methods, Evidence, and Impact, and Department of Medicine, McMaster University, Hamilton, Canada
| | - Rajesh V Thakker
- Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), Churchill Hospital, Headington, Oxford, UK.,Oxford National Institute for Health Research (NIHR) Biomedical Research Centre, Oxford University Hospitals NHS Foundation Trust, John Radcliffe Hospital, Oxford, UK
| | - Weibo Xia
- Department of Endocrinology, Peking Union Medical Collage Hospital, Beijing, China
| | - Maria-Luisa Brandi
- Fondazione Italiana sulla Ricerca sulle Malattie dell'Osso (F.I.R.M.O. Foundation), Florence, Italy
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15
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Iamartino L, Brandi ML. The calcium-sensing receptor in inflammation: Recent updates. Front Physiol 2022; 13:1059369. [PMID: 36467702 PMCID: PMC9716066 DOI: 10.3389/fphys.2022.1059369] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2022] [Accepted: 11/07/2022] [Indexed: 07/30/2023] Open
Abstract
The Calcium-Sensing Receptor (CaSR) is a member of the class C of G-proteins coupled receptors (GPCRs), it plays a pivotal role in calcium homeostasis by directly controlling calcium excretion in the kidneys and indirectly by regulating parathyroid hormone (PTH) release from the parathyroid glands. The CaSR is found to be ubiquitously expressed in the body, playing a plethora of additional functions spanning from fluid secretion, insulin release, neuronal development, vessel tone to cell proliferation and apoptosis, to name but a few. The present review aims to elucidate and clarify the emerging regulatory effects that the CaSR plays in inflammation in several tissues, where it mostly promotes pro-inflammatory responses, with the exception of the large intestine, where contradictory roles have been recently reported. The CaSR has been found to be expressed even in immune cells, where it stimulates immune response and chemokinesis. On the other hand, CaSR expression seems to be boosted under inflammatory stimulus, in particular, by pro-inflammatory cytokines. Because of this, the CaSR has been addressed as a key factor responsible for hypocalcemia and low levels of PTH that are commonly found in critically ill patients under sepsis or after burn injury. Moreover, the CaSR has been found to be implicated in autoimmune-hypoparathyroidism, recently found also in patients treated with immune-checkpoint inhibitors. Given the tight bound between the CaSR, calcium and vitamin D metabolism, we also speculate about their roles in the pathogenesis of severe acute respiratory syndrome coronavirus-19 (SARS-COVID-19) infection and their impact on patients' prognosis. We will further explore the therapeutic potential of pharmacological targeting of the CaSR for the treatment and management of aberrant inflammatory responses.
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Affiliation(s)
- Luca Iamartino
- Department of Experimental Clinical and Biomedical Sciences “Mario Serio”, University of Florence, Florence, Italy
| | - Maria Luisa Brandi
- F.I.R.M.O. (Italian Foundation for the Research on Bone Diseases), Florence, Italy
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16
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Wang WH, Lin DH. Inwardly rectifying K + channels 4.1 and 5.1 (Kir4.1/Kir5.1) in the renal distal nephron. Am J Physiol Cell Physiol 2022; 323:C277-C288. [PMID: 35759440 PMCID: PMC9291425 DOI: 10.1152/ajpcell.00096.2022] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The inwardly rectifying potassium channel (Kir) 4.1 (encoded by KCNJ10) interacts with Kir5.1 (encoded by KCNJ16) to form a major basolateral K+ channel in the renal distal convoluted tubule (DCT), connecting tubule (CNT), and the cortical collecting duct (CCD). Kir4.1/Kir5.1 heterotetramer plays an important role in regulating Na+ and K+ transport in the DCT, CNT, and CCD. A recent development in the field has firmly established the role of Kir4.1/Kir5.1 heterotetramer of the DCT in the regulation of thiazide-sensitive Na-Cl cotransporter (NCC). Changes in Kir4.1/Kir5.1 activity of the DCT are an essential step for the regulation of NCC expression/activity induced by dietary K+ and Na+ intakes and play a role in modulating NCC by type 2 angiotensin II receptor (AT2R), bradykinin type II receptor (BK2R), and β-adrenergic receptor. Since NCC activity determines the Na+ delivery rate to the aldosterone-sensitive distal nephron (ASDN), a distal nephron segment from late DCT to CCD, Kir4.1/Kir5.1 activity plays a critical role not only in the regulation of renal Na+ absorption but also in modulating renal K+ excretion and maintaining K+ homeostasis. Thus, Kir4.1/Kir5.1 activity serves as an important component of renal K+ sensing mechanism. The main focus of this review is to provide an overview regarding the role of Kir4.1 and Kir5.1 of the DCT and CCD in the regulation of renal K+ excretion and Na+ absorption.
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Affiliation(s)
- Wen-Hui Wang
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Dao-Hong Lin
- Department of Pharmacology, New York Medical College, Valhalla, New York
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17
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van Megen WH, Tan RSG, Alexander RT, Dimke H. Differential parathyroid and kidney Ca 2+-sensing receptor activation in autosomal dominant hypocalcemia 1. EBioMedicine 2022; 78:103947. [PMID: 35313217 PMCID: PMC8935519 DOI: 10.1016/j.ebiom.2022.103947] [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] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 02/11/2022] [Accepted: 03/03/2022] [Indexed: 12/04/2022] Open
Abstract
Background Parathyroid Ca2+-sensing receptor (CaSR) activation inhibits parathyroid hormone (PTH) release, while activation of renal CaSRs attenuates Ca2+ transport and increases expression of the pore-blocking claudin-14. Patients with autosomal dominant hypocalcemia 1 (ADH1), due to activating CASR mutations, exhibit hypocalcemia but not always hypercalciuria (elevated Ca2+ in urine). The latter promotes nephrocalcinosis and renal insufficiency. Although CaSRs throughout the body including the kidney harbor activating CASR mutations, it is not understood why only some ADH1 patients display hypercalciuria. Methods Activation of the CaSR was studied in mouse models and a ADH1 patient. In vitro CaSR activation was studied in HEK293 cells. Findings Cldn14 showed blood Ca2+ concentration-dependent regulation, which was absent in mice with kidney-specific Casr deletion, indicating Cldn14 is a suitable marker for chronic CaSR activation in the kidney. Mice with a gain-of-function mutation in the Casr (Nuf) were hypocalcemic with low plasma PTH levels. However, renal CaSRs were not activated at baseline but only after normalizing blood Ca2+ levels. Similarly, significant hypercalciuria was not observed in a ADH1 patient until blood Ca2+ was normalized. In vitro experiments indicate that increased CaSR expression in the parathyroid relative to the kidney could contribute to tissue-specific CaSR activation thresholds. Interpretation Our findings suggest that parathyroid CaSR overactivity can reduce plasma Ca2+ to levels insufficient to activate renal CaSRs, even when an activating mutation is present. These findings identify a conceptually new mechanism of CaSR-dependent Ca2+ balance regulation that aid in explaining the spectrum of hypercalciuria in ADH1 patients. Funding Erasmus+ 2018/E+/4458087, the Canadian Institutes for Health research, the Novo Nordisk Foundation, the Beckett Foundation, the Carlsberg Foundation and Independent Research Fund Denmark.
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Affiliation(s)
- Wouter H van Megen
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, J.B. Winsløws Vej 21, 3rd floor, 5000 Odense C, Denmark; Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Rebecca Siu Ga Tan
- Membrane Protein Disease Research Group, Department of Physiology, University of Alberta, Edmonton, Canada; The Women's and Children's Health Research Institute, Edmonton, Alberta, Canada
| | - R Todd Alexander
- Membrane Protein Disease Research Group, Department of Physiology, University of Alberta, Edmonton, Canada; The Women's and Children's Health Research Institute, Edmonton, Alberta, Canada; Department of Pediatrics, 4-585 Edmonton Clinic Health Academy, University of Alberta, 11405 87th Avenue, Edmonton, Alberta T6G 2R7, Canada.
| | - Henrik Dimke
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, J.B. Winsløws Vej 21, 3rd floor, 5000 Odense C, Denmark; Department of Nephrology, Odense University Hospital, Denmark.
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18
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Elston MS, Elajnaf T, Hannan FM, Thakker RV. Autosomal dominant hypocalcemia type 1 (ADH1) associated with myoclonus and intracerebral calcifications. J Endocr Soc 2022; 6:bvac042. [PMID: 35402765 PMCID: PMC8989155 DOI: 10.1210/jendso/bvac042] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Indexed: 11/19/2022] Open
Abstract
Abstract
Autosomal dominant hypocalcemia type 1 (ADH1) is a disorder of extracellular calcium homeostasis caused by germline gain-of-function mutations of the calcium-sensing receptor (CaSR). Over 35% of ADH1 patients have intracerebral calcifications predominantly affecting the basal ganglia. The clinical consequences of such calcifications remain to be fully characterized, although the majority of patients with these calcifications are considered to be asymptomatic. We report a 20-year-old female proband with a severe form of ADH1 associated with recurrent hypocalcemic and hypercalcemic episodes, persistent childhood hyperphosphatemia, and a low calcium/phosphate ratio. From the age of 18 years, she had experienced recurrent myoclonic jerks affecting the upper limbs that were not associated with epileptic seizures, extra-pyramidal features, cognitive impairment, or alterations in serum calcium concentrations. Computerised tomography (CT) scans revealed calcifications of the globus pallidus regions of the basal ganglia bilaterally, and also the frontal lobes at the grey-white matter junction, and posterior horn choroid plexuses. The patient’s myoclonus resolved following treatment with levetiracetam. CASR mutational analysis identified a reported germline gain-of-function heterozygous missense mutation, c.2363T>G; p.(Phe788Cys), which affects an evolutionarily conserved phenylalanine residue located in transmembrane domain helix 5 of the CaSR protein. Analysis of the cryo-electron microscopy CaSR structure predicted the wild-type Phe788 residue to form interactions with neighbouring phenylalanine residues, which likely maintain the CaSR in an inactive state. The p.(Phe788Cys) mutation was predicted to disrupt these interactions, thereby leading to CaSR activation. These findings reveal myoclonus as a novel finding in an ADH1 patient with intracerebral calcifications.
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Affiliation(s)
- Marianne S Elston
- Waikato Clinical Campus, University of Auckland, Hamilton, New Zealand
| | - Taha Elajnaf
- Nuffield Department of Women’s & Reproductive Health, University of Oxford, Oxford, UK
| | - Fadil M Hannan
- Nuffield Department of Women’s & Reproductive Health, University of Oxford, Oxford, UK
| | - Rajesh V Thakker
- Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
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19
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Vargas-Poussou R. Pathophysiological aspects of the thick ascending limb and novel genetic defects: HELIX syndrome and transient antenatal Bartter syndrome. Pediatr Nephrol 2022; 37:239-252. [PMID: 33733301 DOI: 10.1007/s00467-021-05019-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 01/29/2021] [Accepted: 02/17/2021] [Indexed: 10/21/2022]
Abstract
The thick ascending limb plays a central role in human kidney physiology, participating in sodium reabsorption, urine concentrating mechanisms, calcium and magnesium homeostasis, bicarbonate and ammonium homeostasis, and uromodulin synthesis. This review aims to illustrate the importance of these roles from a pathophysiological point of view by describing the interactions of the key proteins of this segment and by discussing how recently identified and long-known hereditary diseases affect this segment. The descriptions of two recently described salt-losing tubulopathies, transient antenatal Bartter syndrome and HELIX syndrome, which are caused by mutations in MAGED2 and CLDN10 genes, respectively, highlight the role of new players in the modulation of sodium reabsorption the thick ascending limb.
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Affiliation(s)
- Rosa Vargas-Poussou
- Department of Molecular Genetics, Assistance Publique Hôpitaux de Paris, Hôpital Européen Georges-Pompidou, 20-40 rue Leblanc, 75015, Paris, France. .,Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Paris, France. .,Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, Paris, France.
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20
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Chou KJ, Hsu CY, Huang CW, Chen HJ, Ou SH, Chen CL, Lee PT, Fang HC. A new missense mutation of calcium sensing receptor with isoleucine replaced by serine at codon 857 leading to type V Bartter syndrome. Exp Cell Res 2022; 414:113080. [DOI: 10.1016/j.yexcr.2022.113080] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 01/29/2022] [Accepted: 02/10/2022] [Indexed: 02/05/2023]
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21
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Nuñez-Gonzalez L, Carrera N, Garcia-Gonzalez MA. Molecular Basis, Diagnostic Challenges and Therapeutic Approaches of Bartter and Gitelman Syndromes: A Primer for Clinicians. Int J Mol Sci 2021; 22:11414. [PMID: 34768847 PMCID: PMC8584233 DOI: 10.3390/ijms222111414] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 10/13/2021] [Accepted: 10/14/2021] [Indexed: 12/18/2022] Open
Abstract
Gitelman and Bartter syndromes are rare inherited diseases that belong to the category of renal tubulopathies. The genes associated with these pathologies encode electrolyte transport proteins located in the nephron, particularly in the Distal Convoluted Tubule and Ascending Loop of Henle. Therefore, both syndromes are characterized by alterations in the secretion and reabsorption processes that occur in these regions. Patients suffer from deficiencies in the concentration of electrolytes in the blood and urine, which leads to different systemic consequences related to these salt-wasting processes. The main clinical features of both syndromes are hypokalemia, hypochloremia, metabolic alkalosis, hyperreninemia and hyperaldosteronism. Despite having a different molecular etiology, Gitelman and Bartter syndromes share a relevant number of clinical symptoms, and they have similar therapeutic approaches. The main basis of their treatment consists of electrolytes supplements accompanied by dietary changes. Specifically for Bartter syndrome, the use of non-steroidal anti-inflammatory drugs is also strongly supported. This review aims to address the latest diagnostic challenges and therapeutic approaches, as well as relevant recent research on the biology of the proteins involved in disease. Finally, we highlight several objectives to continue advancing in the characterization of both etiologies.
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Affiliation(s)
- Laura Nuñez-Gonzalez
- Grupo de Xenetica e Bioloxia do Desenvolvemento das Enfermidades Renais, Laboratorio de Nefroloxia (No. 11), Instituto de Investigacion Sanitaria de Santiago (IDIS), Complexo Hospitalario de Santiago de Compostela (CHUS), 15706 Santiago de Compostela, Spain;
- Grupo de Medicina Xenomica, Complexo Hospitalario de Santiago de Compostela (CHUS), 15706 Santiago de Compostela, Spain
| | - Noa Carrera
- Grupo de Xenetica e Bioloxia do Desenvolvemento das Enfermidades Renais, Laboratorio de Nefroloxia (No. 11), Instituto de Investigacion Sanitaria de Santiago (IDIS), Complexo Hospitalario de Santiago de Compostela (CHUS), 15706 Santiago de Compostela, Spain;
- Grupo de Medicina Xenomica, Complexo Hospitalario de Santiago de Compostela (CHUS), 15706 Santiago de Compostela, Spain
- RedInRen (Red en Investigación Renal) RETIC (Redes Temáticas de Investigación Cooperativa en Salud), ISCIII (Instituto de Salud Carlos III), 28029 Madrid, Spain
| | - Miguel A. Garcia-Gonzalez
- Grupo de Xenetica e Bioloxia do Desenvolvemento das Enfermidades Renais, Laboratorio de Nefroloxia (No. 11), Instituto de Investigacion Sanitaria de Santiago (IDIS), Complexo Hospitalario de Santiago de Compostela (CHUS), 15706 Santiago de Compostela, Spain;
- Grupo de Medicina Xenomica, Complexo Hospitalario de Santiago de Compostela (CHUS), 15706 Santiago de Compostela, Spain
- RedInRen (Red en Investigación Renal) RETIC (Redes Temáticas de Investigación Cooperativa en Salud), ISCIII (Instituto de Salud Carlos III), 28029 Madrid, Spain
- Fundación Pública Galega de Medicina Xenomica—SERGAS, Complexo Hospitalario de Santiago de Compotela (CHUS), 15706 Santiago de Compostela, Spain
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22
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Tang PK, Geddes RF, Jepson RE, Elliott J. A feline-focused review of chronic kidney disease-mineral and bone disorders - Part 1: Physiology of calcium handling. Vet J 2021; 275:105719. [PMID: 34311095 DOI: 10.1016/j.tvjl.2021.105719] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 06/03/2021] [Accepted: 07/21/2021] [Indexed: 01/01/2023]
Abstract
Mineral derangements are a common consequence of chronic kidney disease (CKD). Despite the well-established role of phosphorus in the pathophysiology of CKD, the implications of calcium disturbances associated with CKD remain equivocal. Calcium plays an essential role in numerous physiological functions in the body and is a fundamental structural component of bone. An understanding of calcium metabolism is required to understand the potential adverse clinical implications and outcomes secondary to the (mal)adaptation of calcium-regulating hormones in CKD. The first part of this two-part review covers the physiology of calcium homeostasis (kidneys, intestines and bones) and details the intimate relationships between calcium-regulating hormones (parathyroid hormone, calcitriol, fibroblast growth factor 23, α-Klotho and calcitonin) and the role of the calcium-sensing receptor.
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Affiliation(s)
- Pak-Kan Tang
- Department of Comparative Biomedical Sciences, Royal Veterinary College, University of London, London, UK.
| | - Rebecca F Geddes
- Department of Clinical Science and Services, Royal Veterinary College, University of London, London, UK
| | - Rosanne E Jepson
- Department of Clinical Science and Services, Royal Veterinary College, University of London, London, UK
| | - Jonathan Elliott
- Department of Comparative Biomedical Sciences, Royal Veterinary College, University of London, London, UK
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23
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Tan RSG, Lee CHL, Dimke H, Todd Alexander R. The role of calcium-sensing receptor signaling in regulating transepithelial calcium transport. Exp Biol Med (Maywood) 2021; 246:2407-2419. [PMID: 33926258 DOI: 10.1177/15353702211010415] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The calcium-sensing receptor (CaSR) plays a critical role in sensing extracellular calcium (Ca2+) and signaling to maintain Ca2+ homeostasis. In the parathyroid, the CaSR regulates secretion of parathyroid hormone, which functions to increase extracellular Ca2+ levels. The CaSR is also located in other organs imperative to Ca2+ homeostasis including the kidney and intestine, where it modulates Ca2+ reabsorption and absorption, respectively. In this review, we describe CaSR expression and its function in transepithelial Ca2+ transport in the kidney and intestine. Activation of the CaSR leads to G protein dependent and independent signaling cascades. The known CaSR signal transduction pathways involved in modulating paracellular and transcellular epithelial Ca2+ transport are discussed. Mutations in the CaSR cause a range of diseases that manifest in altered serum Ca2+ levels. Gain-of-function mutations in the CaSR result in autosomal dominant hypocalcemia type 1, while loss-of-function mutations cause familial hypocalciuric hypercalcemia. Additionally, the putative serine protease, FAM111A, is discussed as a potential regulator of the CaSR because mutations in FAM111A cause Kenny Caffey syndrome type 2, gracile bone dysplasia, and osteocraniostenosis, diseases that are characterized by hypocalcemia, hypoparathyroidism, and bony abnormalities, i.e. share phenotypic features of autosomal dominant hypocalcemia. Recent work has helped to elucidate the effect of CaSR signaling cascades on downstream proteins involved in Ca2+ transport across renal and intestinal epithelia; however, much remains to be discovered.
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Affiliation(s)
- Rebecca Siu Ga Tan
- Department of Physiology, University of Alberta, Edmonton T6G 1C9, Canada.,Membrane Protein Disease Research Group, University of Alberta, Edmonton T6G 1C9, Canada
| | | | - Henrik Dimke
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense 5000, Denmark.,Department of Nephrology, Odense University Hospital, Odense 5000, Denmark
| | - R Todd Alexander
- Department of Physiology, University of Alberta, Edmonton T6G 1C9, Canada.,Membrane Protein Disease Research Group, University of Alberta, Edmonton T6G 1C9, Canada.,Department of Pediatrics, University of Alberta, Edmonton T6G 1C9, Canada
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24
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Schöneberg T, Liebscher I. Mutations in G Protein-Coupled Receptors: Mechanisms, Pathophysiology and Potential Therapeutic Approaches. Pharmacol Rev 2020; 73:89-119. [PMID: 33219147 DOI: 10.1124/pharmrev.120.000011] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
There are approximately 800 annotated G protein-coupled receptor (GPCR) genes, making these membrane receptors members of the most abundant gene family in the human genome. Besides being involved in manifold physiologic functions and serving as important pharmacotherapeutic targets, mutations in 55 GPCR genes cause about 66 inherited monogenic diseases in humans. Alterations of nine GPCR genes are causatively involved in inherited digenic diseases. In addition to classic gain- and loss-of-function variants, other aspects, such as biased signaling, trans-signaling, ectopic expression, allele variants of GPCRs, pseudogenes, gene fusion, and gene dosage, contribute to the repertoire of GPCR dysfunctions. However, the spectrum of alterations and GPCR involvement is probably much larger because an additional 91 GPCR genes contain homozygous or hemizygous loss-of-function mutations in human individuals with currently unidentified phenotypes. This review highlights the complexity of genomic alteration of GPCR genes as well as their functional consequences and discusses derived therapeutic approaches. SIGNIFICANCE STATEMENT: With the advent of new transgenic and sequencing technologies, the number of monogenic diseases related to G protein-coupled receptor (GPCR) mutants has significantly increased, and our understanding of the functional impact of certain kinds of mutations has substantially improved. Besides the classical gain- and loss-of-function alterations, additional aspects, such as biased signaling, trans-signaling, ectopic expression, allele variants of GPCRs, uniparental disomy, pseudogenes, gene fusion, and gene dosage, need to be elaborated in light of GPCR dysfunctions and possible therapeutic strategies.
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Affiliation(s)
- Torsten Schöneberg
- Rudolf Schönheimer Institute of Biochemistry, Molecular Biochemistry, Medical Faculty, Leipzig, Germany
| | - Ines Liebscher
- Rudolf Schönheimer Institute of Biochemistry, Molecular Biochemistry, Medical Faculty, Leipzig, Germany
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Hannan FM, Gorvin CM, Babinsky VN, Olesen MK, Stewart M, Wells S, Cox RD, Nemeth EF, Thakker RV. Calcilytic NPSP795 Increases Plasma Calcium and PTH in an Autosomal Dominant Hypocalcemia Type 1 Mouse Model. JBMR Plus 2020; 4:e10402. [PMID: 33103030 PMCID: PMC7574706 DOI: 10.1002/jbm4.10402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 07/28/2020] [Indexed: 12/30/2022] Open
Abstract
Calcilytics are calcium‐sensing receptor (CaSR) antagonists that reduce the sensitivity of the CaSR to extracellular calcium. Calcilytics have the potential to treat autosomal dominant hypocalcemia type 1 (ADH1), which is caused by germline gain‐of‐function CaSR mutations and leads to symptomatic hypocalcemia, inappropriately low PTH concentrations, and hypercalciuria. To date, only one calcilytic compound, NPSP795, has been evaluated in patients with ADH1: Doses of up to 30 mg per patient have been shown to increase PTH concentrations, but did not significantly alter ionized blood calcium concentrations. The aim of this study was to further investigate NPSP795 for the treatment of ADH1 by undertaking in vitro and in vivo studies involving Nuf mice, which have hypocalcemia in association with a gain‐of‐function CaSR mutation, Leu723Gln. Treatment of HEK293 cells stably expressing the mutant Nuf (Gln723) CaSR with 20nM NPSP795 decreased extracellular Ca2+‐mediated intracellular calcium and phosphorylated ERK responses. An in vivo dose‐ranging study was undertaken by administering a s.c. bolus of NPSP795 at doses ranging from 0 to 30 mg/kg to heterozygous (Casr+/Nuf) and to homozygous (CasrNuf/Nuf) mice, and measuring plasma PTH responses at 30 min postdose. NPSP795 significantly increased plasma PTH concentrations in a dose‐dependent manner with the 30 mg/kg dose causing a maximal (≥10‐fold) rise in PTH. To determine whether NPSP795 can rectify the hypocalcemia of Casr+/Nuf and CasrNuf/Nuf mice, a submaximal dose (25 mg/kg) was administered, and plasma adjusted‐calcium concentrations measured over a 6‐hour period. NPSP795 significantly increased plasma adjusted‐calcium in Casr+/Nuf mice from 1.87 ± 0.03 mmol/L to 2.16 ± 0.06 mmol/L, and in CasrNuf/Nuf mice from 1.70 ± 0.03 mmol/L to 1.89 ± 0.05 mmol/L. Our findings show that NPSP795 elicits dose‐dependent increases in PTH and ameliorates the hypocalcemia in an ADH1 mouse model. Thus, calcilytics such as NPSP795 represent a potential targeted therapy for ADH1. © 2020 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.
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Affiliation(s)
- Fadil M Hannan
- Academic Endocrine Unit, Radcliffe Department of Medicine Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), University of Oxford Oxford UK
| | - Caroline M Gorvin
- Academic Endocrine Unit, Radcliffe Department of Medicine Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), University of Oxford Oxford UK
| | - Valerie N Babinsky
- Academic Endocrine Unit, Radcliffe Department of Medicine Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), University of Oxford Oxford UK
| | - Mie K Olesen
- Academic Endocrine Unit, Radcliffe Department of Medicine Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), University of Oxford Oxford UK
| | - Michelle Stewart
- MRC Mammalian Genetics Unit and Mary Lyon Centre MRC Harwell Institute, Harwell Science and Innovation Campus Oxford UK
| | - Sara Wells
- MRC Mammalian Genetics Unit and Mary Lyon Centre MRC Harwell Institute, Harwell Science and Innovation Campus Oxford UK
| | - Roger D Cox
- MRC Mammalian Genetics Unit and Mary Lyon Centre MRC Harwell Institute, Harwell Science and Innovation Campus Oxford UK
| | | | - Rajesh V Thakker
- Academic Endocrine Unit, Radcliffe Department of Medicine Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), University of Oxford Oxford UK
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Calcium-Sensing Receptor and Regulation of WNK Kinases in the Kidney. Cells 2020; 9:cells9071644. [PMID: 32659887 PMCID: PMC7407487 DOI: 10.3390/cells9071644] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 07/01/2020] [Accepted: 07/06/2020] [Indexed: 12/27/2022] Open
Abstract
The kidney is essential for systemic calcium homeostasis. Urinary calcium excretion can be viewed as an integrative renal response to endocrine and local stimuli. The extracellular calcium-sensing receptor (CaSR) elicits a number of adaptive reactions to increased plasma Ca2+ levels including the control of parathyroid hormone release and regulation of the renal calcium handling. Calcium reabsorption in the distal nephron of the kidney is functionally coupled to sodium transport. Apart from Ca2+ transport systems, CaSR signaling affects relevant distal Na+-(K+)-2Cl- cotransporters, NKCC2 and NCC. NKCC2 and NCC are activated by a kinase cascade comprising with-no-lysine [K] kinases (WNKs) and two homologous Ste20-related kinases, SPAK and OSR1. Gain-of-function mutations within the WNK-SPAK/OSR1-NKCC2/NCC pathway lead to renal salt retention and hypertension, whereas loss-of-function mutations have been associated with salt-losing tubulopathies such as Bartter or Gitelman syndromes. A Bartter-like syndrome has been also described in patients carrying gain-of-function mutations in the CaSR gene. Recent work suggested that CaSR signals via the WNK-SPAK/OSR1 cascade to modulate salt reabsorption along the distal nephron. The review presented here summarizes the latest progress in understanding of functional interactions between CaSR and WNKs and their potential impact on the renal salt handling and blood pressure.
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Syndromes de Bartter–Gitelman. Nephrol Ther 2020; 16:233-243. [DOI: 10.1016/j.nephro.2020.06.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Abstract
Kidney stone disease (nephrolithiasis) is a common problem that can be associated with alterations in urinary solute composition including hypercalciuria. Studies suggest that the prevalence of monogenic kidney stone disorders, including renal tubular acidosis with deafness, Bartter syndrome, primary hyperoxaluria and cystinuria, in patients attending kidney stone clinics is ∼15%. However, for the majority of individuals, nephrolithiasis has a multifactorial aetiology involving genetic and environmental factors. Nonetheless, the genetic influence on stone formation in these idiopathic stone formers remains considerable and twin studies estimate a heritability of >45% for nephrolithiasis and >50% for hypercalciuria. The contribution of polygenic influences from multiple loci have been investigated by genome-wide association and candidate gene studies, which indicate that a number of genes and molecular pathways contribute to the risk of stone formation. Genetic approaches, studying both monogenic and polygenic factors in nephrolithiasis, have revealed that the following have important roles in the aetiology of kidney stones: transporters and channels; ions, protons and amino acids; the calcium-sensing receptor (a G protein-coupled receptor) signalling pathway; and the metabolic pathways for vitamin D, oxalate, cysteine, purines and uric acid. These advances, which have increased our understanding of the pathogenesis of nephrolithiasis, will hopefully facilitate the future development of targeted therapies for precision medicine approaches in patients with nephrolithiasis.
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Affiliation(s)
- Sarah A Howles
- Nuffield Department of Surgical Sciences, University of Oxford, Oxford, UK.,Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Rajesh V Thakker
- Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford, UK.
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Han Y, Cheng H, Shao S, Lang Y, Zhao X, Lin Y, Wang S, Shi X, Liu Z, Shao L. Thirteen novel CLCNKB variants and genotype/phenotype association study in 42 Chinese patients with Bartter syndrome type 3. Endocrine 2020; 68:192-202. [PMID: 31834604 DOI: 10.1007/s12020-019-02156-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 12/02/2019] [Indexed: 12/20/2022]
Abstract
PURPOSE Analyze the genotype of 42 Chinese patients with Bartter syndrome type 3 (BS3) and investigate their correlation between genotype and phenotype. METHODS Identify CLCNKB gene variants by the next-generation sequencing and the multiplex ligation-dependent probe amplification (MLPA), and then evaluate their mutation effects according to 2015 American College of Medical Genetics and Genomics (ACMG) standards and guidelines. RESULTS Thirty-six different variants in CLCNKB gene, including 13 novel ones, were found. The whole gene deletion of CLCNKB gene was the most frequent mutation (40%), and the rate of large deletions is up to 55%. Among 36 variants, six (c.1244T>A, c.1468G>A, c.849_851delCTT, c.359G>T, c.1052G>T, and c.1309G>A) and three (c.228A>C, c.1294_1295TA>CT, and c.1333T>G) variants were classified as "likely pathogenic variants" and "variants with uncertain significance (VUS)," respectively. The other 27 variants were classified as "pathogenic variants". The most common symptoms included: growth retardation (38/42), polydipsia and polyuria (35/42), constipation (31/42), and vomiting (27/42). All patients presented with hypokalemia, hypochloremia, and metabolic alkalosis. The genotype and phenotype association study revealed that who had mutations probably resulting in complete loss of function of both alleles might have severer phenotype. After the treatment that based on indomethacin and potassium chloride, most patients could achieve obvious recovery of growth rate and restoration of hypokalemia. CONCLUSIONS The present study have found 36 variants of CLCNKB gene, including 13 novel ones, which enrich the human gene mutation database and provide valuable references to diagnosis, treatment, and the genetic counseling of Chinese population.
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Affiliation(s)
- Yue Han
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, No. 5 Donghai Middle Road, Qingdao, 266071, PR China
- Central Laboratory, The Affiliated Hospital of Qingdao University, Qingdao, 266003, PR China
| | - Hai Cheng
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, No. 5 Donghai Middle Road, Qingdao, 266071, PR China
| | - Shihong Shao
- Department of Pathology, The Affiliated Hospital of Qingdao University, Qingdao, 266003, PR China
| | - Yanhua Lang
- Department of Nursing, The Affiliated Hospital of Qingdao University, Qingdao, 266003, PR China
| | - Xiangzhong Zhao
- Central Laboratory, The Affiliated Hospital of Qingdao University, Qingdao, 266003, PR China
| | - Yi Lin
- Department of Pathology, The Affiliated Hospital of Qingdao University, Qingdao, 266003, PR China
| | - Sai Wang
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, No. 5 Donghai Middle Road, Qingdao, 266071, PR China
- Central Laboratory, The Affiliated Hospital of Qingdao University, Qingdao, 266003, PR China
| | - Xiaomeng Shi
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, No. 5 Donghai Middle Road, Qingdao, 266071, PR China
- Central Laboratory, The Affiliated Hospital of Qingdao University, Qingdao, 266003, PR China
| | - Zhiying Liu
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, No. 5 Donghai Middle Road, Qingdao, 266071, PR China
- Central Laboratory, The Affiliated Hospital of Qingdao University, Qingdao, 266003, PR China
| | - Leping Shao
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, No. 5 Donghai Middle Road, Qingdao, 266071, PR China.
- Central Laboratory, The Affiliated Hospital of Qingdao University, Qingdao, 266003, PR China.
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Nozu K, Yamamura T, Horinouchi T, Nagano C, Sakakibara N, Ishikura K, Hamada R, Morisada N, Iijima K. Inherited salt-losing tubulopathy: An old condition but a new category of tubulopathy. Pediatr Int 2020; 62:428-437. [PMID: 31830341 DOI: 10.1111/ped.14089] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 08/11/2019] [Accepted: 10/21/2019] [Indexed: 12/16/2022]
Abstract
Bartter syndrome (BS) and Gitelman syndrome (GS) are syndromes associated with congenital tubular dysfunction, characterized by hypokalemia and metabolic alkalosis. Clinically, BS is classified into two types: the severe antenatal/neonatal type, which develops during the fetal period with polyhydramnios and preterm delivery; and the relatively mild classic type, which is usually found during infancy with failure to thrive. GS can be clinically differentiated from BS by its age at onset, usually after school age, or laboratory findings of hypomagnesemia and hypocalciuria. Recent advances in molecular biology have shown that these diseases can be genetically classified into type 1 to 5 BS and GS. As a result, it has become clear that the clinical classification of antenatal/neonatal BS, classic BS, and GS does not always correspond to the clinical symptoms associated with the genotypes in a one-to-one manner; and there is clinically no clear differential border between type 3 BS and GS. This has caused confusion among clinicians in the diagnosis of these diseases. It has been proposed that the disease name "inherited salt-losing tubulopathy" can be used for cases of tubulopathies accompanied by hypokalemia and metabolic alkalosis. It is reasonable to use this term prior to genetic typing into type 1-5 BS or GS, to avoid confusion in a clinical setting. In this article, we review causative genes and phenotypic correlations, diagnosis, and treatment strategies for salt-losing tubulopathy as well as the clinical characteristics of pseudo-BS/GS, which can also be called a "salt-losing disorder".
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Affiliation(s)
- Kandai Nozu
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Tomohiko Yamamura
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Tomoko Horinouchi
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - China Nagano
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Nana Sakakibara
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Kenji Ishikura
- Kitasato University School of Medicine, Sagamihara, Japan
| | - Riku Hamada
- Department of Nephrology, Tokyo Metropolitan Children's Medical Center, Fuchu, Japan
| | - Naoya Morisada
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Kazumoto Iijima
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
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Gorvin CM, Stokes VJ, Boon H, Cranston T, Glück AK, Bahl S, Homfray T, Aung T, Shine B, Lines KE, Hannan FM, Thakker RV. Activating Mutations of the G-protein Subunit α 11 Interdomain Interface Cause Autosomal Dominant Hypocalcemia Type 2. J Clin Endocrinol Metab 2020; 105:5671666. [PMID: 31820785 PMCID: PMC7048683 DOI: 10.1210/clinem/dgz251] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2019] [Accepted: 12/09/2019] [Indexed: 12/30/2022]
Abstract
CONTEXT Autosomal dominant hypocalcemia types 1 and 2 (ADH1 and ADH2) are caused by germline gain-of-function mutations of the calcium-sensing receptor (CaSR) and its signaling partner, the G-protein subunit α 11 (Gα 11), respectively. More than 70 different gain-of-function CaSR mutations, but only 6 different gain-of-function Gα 11 mutations are reported to date. METHODS We ascertained 2 additional ADH families and investigated them for CaSR and Gα 11 mutations. The effects of identified variants on CaSR signaling were evaluated by transiently transfecting wild-type (WT) and variant expression constructs into HEK293 cells stably expressing CaSR (HEK-CaSR), and measuring intracellular calcium (Ca2+i) and MAPK responses following stimulation with extracellular calcium (Ca2+e). RESULTS CaSR variants were not found, but 2 novel heterozygous germline Gα 11 variants, p.Gly66Ser and p.Arg149His, were identified. Homology modeling of these revealed that the Gly66 and Arg149 residues are located at the interface between the Gα 11 helical and GTPase domains, which is involved in guanine nucleotide binding, and this is the site of 3 other reported ADH2 mutations. The Ca2+i and MAPK responses of cells expressing the variant Ser66 or His149 Gα 11 proteins were similar to WT cells at low Ca2+e, but significantly increased in a dose-dependent manner following Ca2+e stimulation, thereby indicating that the p.Gly66Ser and p.Arg149His variants represent pathogenic gain-of-function Gα 11 mutations. Treatment of Ser66- and His149-Gα 11 expressing cells with the CaSR negative allosteric modulator NPS 2143 normalized Ca2+i and MAPK responses. CONCLUSION Two novel ADH2-causing mutations that highlight the Gα 11 interdomain interface as a hotspot for gain-of-function Gα 11 mutations have been identified.
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Affiliation(s)
- Caroline M Gorvin
- Academic Endocrine Unit, Radcliffe Department of Medicine, Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), University of Oxford, Oxford, UK
- Oxford NIHR Biomedical Research Centre, University of Oxford, Churchill Hospital, Oxford, UK
| | - Victoria J Stokes
- Academic Endocrine Unit, Radcliffe Department of Medicine, Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), University of Oxford, Oxford, UK
- Oxford NIHR Biomedical Research Centre, University of Oxford, Churchill Hospital, Oxford, UK
| | - Hannah Boon
- Oxford Molecular Genetics Laboratory, Churchill Hospital, Oxford, UK
| | - Treena Cranston
- Oxford Molecular Genetics Laboratory, Churchill Hospital, Oxford, UK
| | - Anna K Glück
- Academic Endocrine Unit, Radcliffe Department of Medicine, Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), University of Oxford, Oxford, UK
| | - Shailini Bahl
- Department of Paediatrics, Ashford and St. Peter’s Hospitals NHS Foundation Trust, Surrey, UK
| | - Tessa Homfray
- Department of Clinical Genetics, St George’s University Hospital, London, UK
| | - Theingi Aung
- The Centre for Diabetes and Endocrinology, Royal Berkshire NHS Foundation Trust, Reading, UK
| | - Brian Shine
- Department of Clinical Biochemistry, John Radcliffe Hospital, Oxford University Hospitals NHS Trust, Oxford, UK
| | - Kate E Lines
- Academic Endocrine Unit, Radcliffe Department of Medicine, Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), University of Oxford, Oxford, UK
| | - Fadil M Hannan
- Academic Endocrine Unit, Radcliffe Department of Medicine, Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), University of Oxford, Oxford, UK
| | - Rajesh V Thakker
- Academic Endocrine Unit, Radcliffe Department of Medicine, Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), University of Oxford, Oxford, UK
- Oxford NIHR Biomedical Research Centre, University of Oxford, Churchill Hospital, Oxford, UK
- Correspondence and Reprint Requests: Rajesh V. Thakker, Academic Endocrine Unit, Radcliffe Department of Medicine, Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), Churchill Hospital, Oxford OX3 7LJ, United Kingdom. E-mail:
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Madhavan P, Van Do TH, Bale A, Majumdar S. A NOVEL MUTATION IN CALCIUM-SENSING RECEPTOR PRESENTING AS FAMILIAL HYPOCALCIURIC HYPERCALCEMIA IN A YOUNG MAN. AACE Clin Case Rep 2020; 5:e226-e229. [PMID: 31967040 DOI: 10.4158/accr-2018-0236] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Accepted: 01/20/2019] [Indexed: 12/28/2022] Open
Abstract
Objective Familial hypocalciuric hypercalcemia (FHH) is considered a relatively benign condition characterized by elevated serum calcium with relatively low urinary calcium excretion. It typically results from an altered set point in calcium homeostasis originating from mutations in the calcium-sensing receptor (CASR), AP2S1, or GNA11 genes, which encode for the calcium-sensing receptor (CaSR), adaptor-related protein complex 2, and G-protein alpha-11 subunit, respectively. Despite numerous reports of novel variants in these genes associated with FHH, new variants continue to be discovered. Methods We describe a 20-year-old man with a family history of hypercalcemia who had clinical findings compatible with FHH and no evidence of multiple endocrine neoplasia who underwent CASR gene sequencing for evaluation of hypercalcemia. Parathyroid gland single-photon emission computerized tomography scan was normal. Results CASR gene sequencing revealed a previously unreported heterozygous intronic variant at position 1608+3A>G (chromosome 3: 121994892) resulting in a 77-residue deletion. His mother has a history of bipolar disorder and hyperparathyroidism with an adenoma found on imaging, yet our patient had no evidence of adenoma and therefore no surgical intervention was recommended. Given that CaSR plays a role in parathyroid growth, some variants in CASR may ultimately lead to parathyroid hypertrophy and be mistaken for primary hyperparathyroidism. Conclusion Long-term clinical follow up will be helpful in understanding the ultimate effects of specific CASR mutations on parathyroid growth or progression to significant hypercalcemia.
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Nephrocalcinosis: A Review of Monogenic Causes and Insights They Provide into This Heterogeneous Condition. Int J Mol Sci 2020; 21:ijms21010369. [PMID: 31935940 PMCID: PMC6981752 DOI: 10.3390/ijms21010369] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 01/01/2020] [Accepted: 01/02/2020] [Indexed: 12/19/2022] Open
Abstract
The abnormal deposition of calcium within renal parenchyma, termed nephrocalcinosis, frequently occurs as a result of impaired renal calcium handling. It is closely associated with renal stone formation (nephrolithiasis) as elevated urinary calcium levels (hypercalciuria) are a key common pathological feature underlying these clinical presentations. Although monogenic causes of nephrocalcinosis and nephrolithiasis are rare, they account for a significant disease burden with many patients developing chronic or end-stage renal disease. Identifying underlying genetic mutations in hereditary cases of nephrocalcinosis has provided valuable insights into renal tubulopathies that include hypercalciuria within their varied phenotypes. Genotypes affecting other enzyme pathways, including vitamin D metabolism and hepatic glyoxylate metabolism, are also associated with nephrocalcinosis. As the availability of genetic testing becomes widespread, we cannot be imprecise in our approach to nephrocalcinosis. Monogenic causes of nephrocalcinosis account for a broad range of phenotypes. In cases such as Dent disease, supportive therapies are limited, and early renal replacement therapies are necessitated. In cases such as renal tubular acidosis, a good renal prognosis can be expected providing effective treatment is implemented. It is imperative we adopt a precision-medicine approach to ensure patients and their families receive prompt diagnosis, effective, tailored treatment and accurate prognostic information.
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Milatz S. A Novel Claudinopathy Based on Claudin-10 Mutations. Int J Mol Sci 2019; 20:ijms20215396. [PMID: 31671507 PMCID: PMC6862131 DOI: 10.3390/ijms20215396] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 10/26/2019] [Accepted: 10/27/2019] [Indexed: 02/06/2023] Open
Abstract
Claudins are key components of the tight junction, sealing the paracellular cleft or composing size-, charge- and water-selective paracellular channels. Claudin-10 occurs in two major isoforms, claudin-10a and claudin-10b, which constitute paracellular anion or cation channels, respectively. For several years after the discovery of claudin-10, its functional relevance in men has remained elusive. Within the past two years, several studies appeared, describing patients with different pathogenic variants of the CLDN10 gene. Patients presented with dysfunction of kidney, exocrine glands and skin. This review summarizes and compares the recently published studies reporting on a novel autosomal-recessive disorder based on claudin-10 mutations.
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Affiliation(s)
- Susanne Milatz
- Institute of Physiology, Kiel University, Christian-Albrechts-Platz 4, 24118 Kiel, Germany.
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van der Wijst J, Belge H, Bindels RJM, Devuyst O. Learning Physiology From Inherited Kidney Disorders. Physiol Rev 2019; 99:1575-1653. [PMID: 31215303 DOI: 10.1152/physrev.00008.2018] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The identification of genes causing inherited kidney diseases yielded crucial insights in the molecular basis of disease and improved our understanding of physiological processes that operate in the kidney. Monogenic kidney disorders are caused by mutations in genes coding for a large variety of proteins including receptors, channels and transporters, enzymes, transcription factors, and structural components, operating in specialized cell types that perform highly regulated homeostatic functions. Common variants in some of these genes are also associated with complex traits, as evidenced by genome-wide association studies in the general population. In this review, we discuss how the molecular genetics of inherited disorders affecting different tubular segments of the nephron improved our understanding of various transport processes and of their involvement in homeostasis, while providing novel therapeutic targets. These include inherited disorders causing a dysfunction of the proximal tubule (renal Fanconi syndrome), with emphasis on epithelial differentiation and receptor-mediated endocytosis, or affecting the reabsorption of glucose, the handling of uric acid, and the reabsorption of sodium, calcium, and magnesium along the kidney tubule.
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Affiliation(s)
- Jenny van der Wijst
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center , Nijmegen , The Netherlands ; Institute of Physiology, University of Zurich , Zurich , Switzerland ; and Division of Nephrology, Institute of Experimental and Clinical Research (IREC), Medical School, Université catholique de Louvain, Brussels, Belgium
| | - Hendrica Belge
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center , Nijmegen , The Netherlands ; Institute of Physiology, University of Zurich , Zurich , Switzerland ; and Division of Nephrology, Institute of Experimental and Clinical Research (IREC), Medical School, Université catholique de Louvain, Brussels, Belgium
| | - René J M Bindels
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center , Nijmegen , The Netherlands ; Institute of Physiology, University of Zurich , Zurich , Switzerland ; and Division of Nephrology, Institute of Experimental and Clinical Research (IREC), Medical School, Université catholique de Louvain, Brussels, Belgium
| | - Olivier Devuyst
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center , Nijmegen , The Netherlands ; Institute of Physiology, University of Zurich , Zurich , Switzerland ; and Division of Nephrology, Institute of Experimental and Clinical Research (IREC), Medical School, Université catholique de Louvain, Brussels, Belgium
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Shaik FA, Jaggupilli A, Chelikani P. Highly conserved intracellular H208 residue influences agonist selectivity in bitter taste receptor T2R14. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1861:183057. [PMID: 31493373 DOI: 10.1016/j.bbamem.2019.183057] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 08/23/2019] [Accepted: 08/26/2019] [Indexed: 11/19/2022]
Abstract
Bitter taste receptors (T2Rs) are a specialized class of cell membrane receptors of the G protein-coupled receptor family and perform a crucial role in chemosensation. The 25 T2Rs in humans are activated by structurally diverse ligands of plant, animal and microbial origin. The mechanisms of activation of these receptors are poorly understood. Therefore, identification of structural determinants of T2Rs that regulate its efficacy could be beneficial in understanding the molecular mechanisms of T2R activation. In this work, we characterized a highly conserved histidine (H208), present at TM5-ICL3 region of T2R14 and its role in agonist-induced T2R14 signaling. Surprisingly, mutation of the conserved H208 (H208A) did not result in increased basal activity of T2R14, in contrast to similar H206A mutation in T2R4 that showed constitutive or basal activity. However, H208A mutation in T2R14 resulted in an increase in agonist-induced efficacy for Flufenamic acid (FFA). Interestingly, H208A did not affect the potency of another T2R14 agonist Diphenhydramine (DPH). The H208R compensatory mutation showed FFA response similar to wild-type T2R14. Molecular modeling suggests a FFA-induced shift in TM3 and TM5 helices of H208A, which changes the network of interactions connecting TM5-ICL3-TM6. This report identifies a crucial residue on the intracellular surface of T2Rs that is involved in bitter ligand selectivity. It also highlights the varied roles carried out by some conserved residues in different T2Rs.
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Affiliation(s)
- Feroz Ahmed Shaik
- Manitoba Chemosensory Biology Research Group, Department of Oral Biology, University of Manitoba, Children's Hospital Research Institute of Manitoba, Winnipeg, MB, Canada
| | - Appalaraju Jaggupilli
- Manitoba Chemosensory Biology Research Group, Department of Oral Biology, University of Manitoba, Children's Hospital Research Institute of Manitoba, Winnipeg, MB, Canada
| | - Prashen Chelikani
- Manitoba Chemosensory Biology Research Group, Department of Oral Biology, University of Manitoba, Children's Hospital Research Institute of Manitoba, Winnipeg, MB, Canada.
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Tokonami N, Olinger E, Debaix H, Houillier P, Devuyst O. The excretion of uromodulin is modulated by the calcium-sensing receptor. Kidney Int 2019; 94:882-886. [PMID: 30348305 DOI: 10.1016/j.kint.2018.07.022] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2018] [Revised: 06/28/2018] [Accepted: 07/05/2018] [Indexed: 11/16/2022]
Abstract
Uromodulin is produced in the thick ascending limb, but little is known about regulation of its excretion in urine. Using mouse and cellular models, we demonstrate that excretion of uromodulin by thick ascending limb cells is increased or decreased upon inactivation or activation of the calcium-sensing receptor (CaSR), respectively. These effects reflect changes in uromodulin trafficking and likely involve alterations in intracellular cyclic adenosine monophosphate (cAMP) levels. Administration of the CaSR agonist cinacalcet led to a rapid reduction of urinary uromodulin excretion in healthy subjects. Modulation of uromodulin excretion by the CaSR may be clinically relevant considering the increasing use of CaSR modulators.
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Affiliation(s)
- Natsuko Tokonami
- Institute of Physiology, University of Zurich, Zurich, Switzerland
| | - Eric Olinger
- Institute of Physiology, University of Zurich, Zurich, Switzerland
| | - Huguette Debaix
- Institute of Physiology, University of Zurich, Zurich, Switzerland
| | - Pascal Houillier
- Sorbonne Université, UPMC Univ Paris 06, INSERM, Université Paris Descartes, UMR_S 1138 Team 3, Centre de Recherche des Cordeliers, Paris, France
| | - Olivier Devuyst
- Institute of Physiology, University of Zurich, Zurich, Switzerland.
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Khan RN, Saba F. Osteomalacia in a Case of Adult-Onset Bartter Syndrome. Eur J Case Rep Intern Med 2019; 5:000764. [PMID: 30756015 PMCID: PMC6346954 DOI: 10.12890/2018_000764] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 11/12/2017] [Indexed: 11/24/2022] Open
Abstract
Bartter syndrome is a rare heterogeneous disease characterised by a deficiency in sodium and chloride absorption. Gain-of-function mutations in the CASR gene have been described in some patients with Bartter syndrome associated with hypocalcaemia and hypercalciuria. We describe a case of adult-onset Bartter syndrome with hypocalcaemia severe enough to cause osteomalacia.
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Affiliation(s)
- Rashid Naseem Khan
- Internal Medicine, Liaquat College of Medicine and Dentistry and Darul Sehat Hospital, Karachi, Pakistan.,Patel Hospital, Karachi, Pakistan
| | - Farhana Saba
- Internal Medicine, Liaquat College of Medicine and Dentistry and Darul Sehat Hospital, Karachi, Pakistan
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Abstract
Bartter and Gitelman syndromes are conditions characterized by renal salt-wasting. Clinical presentations range from severe antenatal disease to asymptomatic with incidental diagnosis. Hypokalemic hypochloremic metabolic alkalosis is the common feature. Bartter variants may be associated with polyuria and weakness. Gitelman syndrome is often subtle, and typically diagnosed later life with incidental hypokalemia and hypomagnesemia. Treatment may involve fluid and electrolyte replenishment, prostaglandin inhibition, and renin-angiotensin-aldosterone system axis disruption. Investigators have identified causative mutations but genotypic-phenotypic correlations are still being characterized. Collaborative registries will allow improved classification schema and development of effective treatments.
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Affiliation(s)
- Rosanna Fulchiero
- Department of Pediatrics, Inova Children's Hospital, 3300 Gallows Road, Falls Church, VA 22042, USA
| | - Patricia Seo-Mayer
- Department of Pediatrics, Inova Children's Hospital, 3300 Gallows Road, Falls Church, VA 22042, USA; Division of Nephrology and Hypertension, Pediatric Specialists of Virginia, 3023 Hamaker Court, Suite 600, Fairfax, VA 22031, USA; Virginia Commonwealth School of Medicine, Richmond, VA, USA.
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Abstract
PURPOSE OF REVIEW Antenatal Bartter's syndrome (aBS) is the most severe form of Bartter's syndrome, requiring close follow-up, in particular during the neonatal period, primarily because of prematurity. The recent identification of a novel and very severe form of aBS merits an update on this topic. RECENT FINDING Despite the identification of several genes involved in Bartter's syndrome, about 20% of patients clinically diagnosed with aBS remained without genetic explanation for decades. We recently identified mutations in MAGED2 as a cause of an X-linked form of aBS characterized by a very early onset of severe polyhydramnios and extreme prematurity leading to high mortality. Remarkably, all symptoms in surviving patients with MAGE-D2 mutations resolve spontaneously, within weeks after preterm birth. Interestingly, MAGE-D2 affects the expression of the sodium chloride cotransporters NKCC2 and NCC, explaining thereby the severity of the disease. Importantly, a more recent analysis of MAGED2 in a large French cohort of patients with aBS confirmed our data and showed that females can also be affected. SUMMARY MAGE-D2 is critical for renal salt reabsorption in the fetus, amniotic fluid volume regulation, and maintenance of pregnancy. Most importantly, MAGED2 must be included in the genetic screening of every form of aBS.
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Teulon J, Planelles G, Sepúlveda FV, Andrini O, Lourdel S, Paulais M. Renal Chloride Channels in Relation to Sodium Chloride Transport. Compr Physiol 2018; 9:301-342. [DOI: 10.1002/cphy.c180024] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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42
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Hannan FM, Kallay E, Chang W, Brandi ML, Thakker RV. The calcium-sensing receptor in physiology and in calcitropic and noncalcitropic diseases. Nat Rev Endocrinol 2018; 15:33-51. [PMID: 30443043 PMCID: PMC6535143 DOI: 10.1038/s41574-018-0115-0] [Citation(s) in RCA: 199] [Impact Index Per Article: 33.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The Ca2+-sensing receptor (CaSR) is a dimeric family C G protein-coupled receptor that is expressed in calcitropic tissues such as the parathyroid glands and the kidneys and signals via G proteins and β-arrestin. The CaSR has a pivotal role in bone and mineral metabolism, as it regulates parathyroid hormone secretion, urinary Ca2+ excretion, skeletal development and lactation. The importance of the CaSR for these calcitropic processes is highlighted by loss-of-function and gain-of-function CaSR mutations that cause familial hypocalciuric hypercalcaemia and autosomal dominant hypocalcaemia, respectively, and also by the fact that alterations in parathyroid CaSR expression contribute to the pathogenesis of primary and secondary hyperparathyroidism. Moreover, the CaSR is an established therapeutic target for hyperparathyroid disorders. The CaSR is also expressed in organs not involved in Ca2+ homeostasis: it has noncalcitropic roles in lung and neuronal development, vascular tone, gastrointestinal nutrient sensing, wound healing and secretion of insulin and enteroendocrine hormones. Furthermore, the abnormal expression or function of the CaSR is implicated in cardiovascular and neurological diseases, as well as in asthma, and the CaSR is reported to protect against colorectal cancer and neuroblastoma but increase the malignant potential of prostate and breast cancers.
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Affiliation(s)
- Fadil M Hannan
- Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, UK
- Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Enikö Kallay
- Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria
| | - Wenhan Chang
- Endocrine Research Unit, Veterans Affairs Medical Center, University of California, San Francisco, San Francisco, CA, USA
| | - Maria Luisa Brandi
- Metabolic Bone Diseases Unit, Department of Surgery and Translational Medicine, University of Florence, Florence, Italy.
| | - Rajesh V Thakker
- Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford, UK.
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Abstract
Bartter syndrome is an inherited renal tubular disorder caused by a defective salt reabsorption in the thick ascending limb of loop of Henle, resulting in salt wasting, hypokalemia, and metabolic alkalosis. Mutations of several genes encoding the transporters and channels involved in salt reabsorption in the thick ascending limb cause different types of Bartter syndrome. A poor phenotype-genotype relationship due to the interaction with other cotransporters and different degrees of compensation through alternative pathways is currently reported. However, phenotypic identification still remains the first step to guide the suspicion of Bartter syndrome. Given the rarity of the syndrome, and the lack of genetic characterization in most cases, limited clinical evidence for treatment is available and the therapy is based mainly on the comprehension of renal physiology and relies on the physician's personal experiences. A better understanding of the mutated channels and transporters could possibly generate targets for specific treatment in the future, also encompassing drugs aiming to correct deficiencies in folding or plasma membrane expression of the mutated proteins.
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Affiliation(s)
- Tamara da Silva Cunha
- Nephrology Division, Universidade Federal de São Paulo (UNIFESP), Escola Paulista de Medicina, São Paulo, Brazil,
| | - Ita Pfeferman Heilberg
- Nephrology Division, Universidade Federal de São Paulo (UNIFESP), Escola Paulista de Medicina, São Paulo, Brazil,
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Gorvin CM. Insights into calcium-sensing receptor trafficking and biased signalling by studies of calcium homeostasis. J Mol Endocrinol 2018; 61:R1-R12. [PMID: 29599414 DOI: 10.1530/jme-18-0049] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 03/29/2018] [Indexed: 12/18/2022]
Abstract
The calcium-sensing receptor (CASR) is a class C G-protein-coupled receptor (GPCR) that detects extracellular calcium concentrations, and modulates parathyroid hormone secretion and urinary calcium excretion to maintain calcium homeostasis. The CASR utilises multiple heterotrimeric G-proteins to mediate signalling effects including activation of intracellular calcium release; mitogen-activated protein kinase (MAPK) pathways; membrane ruffling; and inhibition of cAMP production. By studying germline mutations in the CASR and proteins within its signalling pathway that cause hyper- and hypocalcaemic disorders, novel mechanisms governing GPCR signalling and trafficking have been elucidated. This review focusses on two recently described pathways that provide novel insights into CASR signalling and trafficking mechanisms. The first, identified by studying a CASR gain-of-function mutation that causes autosomal dominant hypocalcaemia (ADH), demonstrated a structural motif located between the third transmembrane domain and the second extracellular loop of the CASR that mediates biased signalling by activating a novel β-arrestin-mediated G-protein-independent pathway. The second, in which the mechanism by which adaptor protein-2 σ-subunit (AP2σ) mutations cause familial hypocalciuric hypercalcaemia (FHH) was investigated, demonstrated that AP2σ mutations impair CASR internalisation and reduce multiple CASR-mediated signalling pathways. Furthermore, these studies showed that the CASR can signal from the cell surface using multiple G-protein pathways, whilst sustained signalling is mediated only by the Gq/11 pathway. Thus, studies of FHH- and ADH-associated mutations have revealed novel steps by which CASR mediates signalling and compartmental bias, and these pathways could provide new targets for therapies for patients with calcaemic disorders.
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Affiliation(s)
- Caroline M Gorvin
- Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Birmingham, UK
- Centre for Endocrinology, Diabetes and Metabolism (CEDAM), Birmingham Health Partners, Birmingham, UK
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46
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Congenital chloride diarrhea needs to be distinguished from Bartter and Gitelman syndrome. J Hum Genet 2018; 63:887-892. [DOI: 10.1038/s10038-018-0470-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 04/18/2018] [Accepted: 04/30/2018] [Indexed: 12/19/2022]
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Bazúa-Valenti S, Rojas-Vega L, Castañeda-Bueno M, Barrera-Chimal J, Bautista R, Cervantes-Pérez LG, Vázquez N, Plata C, Murillo-de-Ozores AR, González-Mariscal L, Ellison DH, Riccardi D, Bobadilla NA, Gamba G. The Calcium-Sensing Receptor Increases Activity of the Renal NCC through the WNK4-SPAK Pathway. J Am Soc Nephrol 2018; 29:1838-1848. [PMID: 29848507 DOI: 10.1681/asn.2017111155] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Accepted: 04/10/2018] [Indexed: 01/07/2023] Open
Abstract
Background Hypercalciuria can result from activation of the basolateral calcium-sensing receptor (CaSR), which in the thick ascending limb of Henle's loop controls Ca2+ excretion and NaCl reabsorption in response to extracellular Ca2+ However, the function of CaSR in the regulation of NaCl reabsorption in the distal convoluted tubule (DCT) is unknown. We hypothesized that CaSR in this location is involved in activating the thiazide-sensitive NaCl cotransporter (NCC) to prevent NaCl loss.Methods We used a combination of in vitro and in vivo models to examine the effects of CaSR on NCC activity. Because the KLHL3-WNK4-SPAK pathway is involved in regulating NaCl reabsorption in the DCT, we assessed the involvement of this pathway as well.Results Thiazide-sensitive 22Na+ uptake assays in Xenopus laevis oocytes revealed that NCC activity increased in a WNK4-dependent manner upon activation of CaSR with Gd3+ In HEK293 cells, treatment with the calcimimetic R-568 stimulated SPAK phosphorylation only in the presence of WNK4. The WNK4 inhibitor WNK463 also prevented this effect. Furthermore, CaSR activation in HEK293 cells led to phosphorylation of KLHL3 and WNK4 and increased WNK4 abundance and activity. Finally, acute oral administration of R-568 in mice led to the phosphorylation of NCC.Conclusions Activation of CaSR can increase NCC activity via the WNK4-SPAK pathway. It is possible that activation of CaSR by Ca2+ in the apical membrane of the DCT increases NaCl reabsorption by NCC, with the consequent, well known decrease of Ca2+ reabsorption, further promoting hypercalciuria.
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Affiliation(s)
- Silvana Bazúa-Valenti
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico.,Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - Lorena Rojas-Vega
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - María Castañeda-Bueno
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - Jonatan Barrera-Chimal
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | | | | | - Norma Vázquez
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Consuelo Plata
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - Adrián R Murillo-de-Ozores
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico.,Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - Lorenza González-Mariscal
- Department of Physiology, Biophysics and Neuroscience, Center for Research and Advanced Studies (Cinvestav), Mexico City, Mexico
| | - David H Ellison
- Department of Medicine, Oregon Health and Science University, Portland, Oregon.,Renal Section, Veterans Administration Portland Health Care System, Portland, Oregon
| | - Daniela Riccardi
- School of Biosciences, Cardiff University, Cardiff, United Kingdom; and
| | - Norma A Bobadilla
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico.,Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - Gerardo Gamba
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico; .,Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico.,Tecnológico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Monterrey, Nuevo León, Mexico
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Abstract
PURPOSE OF REVIEW Antenatal Bartter syndrome (aBS) is a heterogenous disease resulting from defective ion transport in the thick ascending limb of the loop of Henle. Novel insights into the pathophysiology, as well as the recent identification of a novel genetic cause of aBS, merit an update on this topic. RECENT FINDINGS In aBS, severe salt losing is further aggravated by defective salt sensing in the macula densa, where a reduced tubular salt concentration is perceived and glomerular filtration is increased instead of decreased. As patients with aBS come of age, there is an increased incidence of proteinuria and impaired renal function.Moreover, we recently reported a new form of aBS. Indeed, we described a series of nine families in whom pregnancies with male fetuses where complicated by acute polyhydramnios, preterm delivery and with severe but transient polyuria. We identified mutations in melanoma-associated antigen D2 in all study participants and showed, in vivo and in vitro, reduced expression of the furosemide and thiazide sensitive transporters sodium-potassium-2-chloride cotransporter and sodium chloride cotransporter, respectively. SUMMARY Genetic studies revealed the complexity of ion transport in the thick ascending limb of the loop of Henle and will help to clarify the pathophysiology, which is essential to design new therapies.
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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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50
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Zacchia M, Capolongo G, Rinaldi L, Capasso G. The importance of the thick ascending limb of Henle's loop in renal physiology and pathophysiology. Int J Nephrol Renovasc Dis 2018; 11:81-92. [PMID: 29497325 PMCID: PMC5818843 DOI: 10.2147/ijnrd.s154000] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The thick ascending limb (TAL) of Henle’s loop is a crucial segment for many tasks of the nephron. Indeed, the TAL is not only a mainstay for reabsorption of sodium (Na+), potassium (K+), and divalent cations such as calcium (Ca2+) and magnesium (Mg2+) from the luminal fluid, but also has an important role in urine concentration, overall acid–base homeostasis, and ammonia cycle. Transcellular Na+ transport along the TAL is a prerequisite for Na+, K+, Ca2+, Mg2+ homeostasis, and water reabsorption, the latter through its contribution in the generation of the cortico-medullar osmotic gradient. The role of this nephron site in acid–base balance, via bicarbonate reabsorption and acid secretion, is sometimes misunderstood by clinicians. This review describes in detail these functions, reporting in addition to the well-known molecular mechanisms, some novel findings from the current literature; moreover, the pathophysiology and the clinical relevance of primary or acquired conditions caused by TAL dysfunction are discussed. Knowing the physiology of the TAL is fundamental for clinicians, for a better understanding and management of rare and common conditions, such as tubulopathies, hypertension, and loop diuretics abuse.
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Affiliation(s)
- Miriam Zacchia
- Division of Nephrology, Department of Cardio-Thoracic and Respiratory Sciences, Università della Campania "Luigi Vanvitelli", Naples, Italy
| | - Giovanna Capolongo
- Division of Nephrology, Department of Cardio-Thoracic and Respiratory Sciences, Università della Campania "Luigi Vanvitelli", Naples, Italy
| | - Luca Rinaldi
- Division of Nephrology, Department of Cardio-Thoracic and Respiratory Sciences, Università della Campania "Luigi Vanvitelli", Naples, Italy
| | - Giovambattista Capasso
- Division of Nephrology, Department of Cardio-Thoracic and Respiratory Sciences, Università della Campania "Luigi Vanvitelli", Naples, Italy
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