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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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2
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Gonzalez-Rodriguez M, Marin-Valencia I. Metabolic Determinants of Cerebellar Circuit Formation and Maintenance. CEREBELLUM (LONDON, ENGLAND) 2023:10.1007/s12311-023-01641-2. [PMID: 38123901 DOI: 10.1007/s12311-023-01641-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 11/27/2023] [Indexed: 12/23/2023]
Abstract
Cells configure their metabolism in a synchronized and timely manner to meet their energy demands throughout development and adulthood. Transitions of developmental stages are coupled to metabolic shifts, such that glycolysis is highly active during cell proliferation, whereas oxidative phosphorylation prevails in postmitotic states. In the cerebellum, metabolic transitions are remarkable given its protracted developmental timelines. Such distinctive feature, along with its high neuronal density and metabolic demands, make the cerebellum highly vulnerable to metabolic insults. Despite the expansion of metabolomic approaches to uncover biological mechanisms, little is known about the role of metabolism on cerebellar development and maintenance. To illuminate the intricate connections between metabolism, physiology, and cerebellar disorders, we examined here the impact of metabolism on cerebellar growth, maturation, and adulthood through the lens of inborn errors of metabolism.
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Affiliation(s)
- Manuel Gonzalez-Rodriguez
- The Abimael Laboratory of Neurometabolism, Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Isaac Marin-Valencia
- The Abimael Laboratory of Neurometabolism, Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
- Departments of Neuroscience, Genetics and Genomics Medicine, and Pediatrics Icahn School of Medicine at Mount Sinai, New York, NY, USA.
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Paulhus K, Glasscock E. Novel Genetic Variants Expand the Functional, Molecular, and Pathological Diversity of KCNA1 Channelopathy. Int J Mol Sci 2023; 24:8826. [PMID: 37240170 PMCID: PMC10219020 DOI: 10.3390/ijms24108826] [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: 04/26/2023] [Revised: 05/11/2023] [Accepted: 05/13/2023] [Indexed: 05/28/2023] Open
Abstract
The KCNA1 gene encodes Kv1.1 voltage-gated potassium channel α subunits, which are crucial for maintaining healthy neuronal firing and preventing hyperexcitability. Mutations in the KCNA1 gene can cause several neurological diseases and symptoms, such as episodic ataxia type 1 (EA1) and epilepsy, which may occur alone or in combination, making it challenging to establish simple genotype-phenotype correlations. Previous analyses of human KCNA1 variants have shown that epilepsy-linked mutations tend to cluster in regions critical for the channel's pore, whereas EA1-associated mutations are evenly distributed across the length of the protein. In this review, we examine 17 recently discovered pathogenic or likely pathogenic KCNA1 variants to gain new insights into the molecular genetic basis of KCNA1 channelopathy. We provide the first systematic breakdown of disease rates for KCNA1 variants in different protein domains, uncovering potential location biases that influence genotype-phenotype correlations. Our examination of the new mutations strengthens the proposed link between the pore region and epilepsy and reveals new connections between epilepsy-related variants, genetic modifiers, and respiratory dysfunction. Additionally, the new variants include the first two gain-of-function mutations ever discovered for KCNA1, the first frameshift mutation, and the first mutations located in the cytoplasmic N-terminal domain, broadening the functional and molecular scope of KCNA1 channelopathy. Moreover, the recently identified variants highlight emerging links between KCNA1 and musculoskeletal abnormalities and nystagmus, conditions not typically associated with KCNA1. These findings improve our understanding of KCNA1 channelopathy and promise to enhance personalized diagnosis and treatment for individuals with KCNA1-linked disorders.
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Affiliation(s)
| | - Edward Glasscock
- Department of Biological Sciences, Southern Methodist University, Dallas, TX 75275, USA;
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Ray E, Mohan K, Ahmad S, Wolf MTF. Physiology of a Forgotten Electrolyte-Magnesium Disorders. ADVANCES IN KIDNEY DISEASE AND HEALTH 2023; 30:148-163. [PMID: 36868730 DOI: 10.1053/j.akdh.2022.12.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2022] [Revised: 11/26/2022] [Accepted: 12/06/2022] [Indexed: 03/05/2023]
Abstract
Magnesium (Mg2+) is the second most common intracellular cation and the fourth most abundant element on earth. However, Mg2+ is a frequently overlooked electrolyte and often not measured in patients. While hypomagnesemia is common in 15% of the general population, hypermagnesemia is typically only found in preeclamptic women after Mg2+ therapy and in patients with ESRD. Mild to moderate hypomagnesemia has been associated with hypertension, metabolic syndrome, type 2 diabetes mellitus, CKD, and cancer. Nutritional Mg2+ intake and enteral Mg2+ absorption are important for Mg2+ homeostasis, but the kidneys are the key regulators of Mg2+ homeostasis by limiting urinary excretion to less than 4% while the gastrointestinal tract loses over 50% of the Mg2+ intake in the feces. Here, we review the physiological relevance of Mg2+, the current knowledge of Mg2+ absorption in the kidneys and the gut, the different causes of hypomagnesemia, and a diagnostic approach on how to assess Mg2+ status. We highlight the latest discoveries of monogenetic conditions causing hypomagnesemia, which have enhanced our understanding of tubular Mg2+ absorption. We will also discuss external and iatrogenic causes of hypomagnesemia and advances in the treatment of hypomagnesemia.
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Affiliation(s)
- Evan Ray
- Renal-Electrolyte Division, Department of Internal Medicine, University of Pittsburgh, PA
| | - Krithika Mohan
- Department of Nephrology, Hosmat Hospital, HBR Layout, Bangalore, India
| | - Syeda Ahmad
- Renal-Electrolyte Division, Department of Internal Medicine, University of Pittsburgh, PA
| | - Matthias T F Wolf
- Pediatric Nephrology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX.
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Abstract
Mg2+ is essential for many cellular and physiological processes, including muscle contraction, neuronal activity, and metabolism. Consequently, the blood Mg2+ concentration is tightly regulated by balanced intestinal Mg2+ absorption, renal Mg2+ excretion, and Mg2+ storage in bone and soft tissues. In recent years, the development of novel transgenic animal models and identification of Mendelian disorders has advanced our current insight in the molecular mechanisms of Mg2+ reabsorption in the kidney. In the proximal tubule, Mg2+ reabsorption is dependent on paracellular permeability by claudin-2/12. In the thick ascending limb of Henle's loop, the claudin-16/19 complex provides a cation-selective pore for paracellular Mg2+ reabsorption. The paracellular Mg2+ reabsorption in this segment is regulated by the Ca2+-sensing receptor, parathyroid hormone, and mechanistic target of rapamycin (mTOR) signaling. In the distal convoluted tubule, the fine tuning of Mg2+ reabsorption takes place by transcellular Mg2+ reabsorption via transient receptor potential melastatin-like types 6 and 7 (TRPM6/TRPM7) divalent cation channels. Activity of TRPM6/TRPM7 is dependent on hormonal regulation, metabolic activity, and interacting proteins. Basolateral Mg2+ extrusion is still poorly understood but is probably dependent on the Na+ gradient. Cyclin M2 and SLC41A3 are the main candidates to act as Na+/Mg2+ exchangers. Consequently, disturbances of basolateral Na+/K+ transport indirectly result in impaired renal Mg2+ reabsorption in the distal convoluted tubule. Altogether, this review aims to provide an overview of the molecular mechanisms of Mg2+ reabsorption in the kidney, specifically focusing on transgenic mouse models and human hereditary diseases.
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Affiliation(s)
- Jeroen H F de Baaij
- Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
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Gallafassi E, Bezerra M, Rebouças N. Control of sodium and potassium homeostasis by renal distal convoluted tubules. Braz J Med Biol Res 2023; 56:e12392. [PMID: 36790288 PMCID: PMC9925193 DOI: 10.1590/1414-431x2023e12392] [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: 10/12/2022] [Accepted: 12/17/2022] [Indexed: 02/12/2023] Open
Abstract
Distal convoluted tubules (DCT), which contain the Na-Cl cotransporter (NCC) inhibited by thiazide diuretics, undergo complex modulation to preserve Na+ and K+ homeostasis. The lysine kinases 1 and 4 (WNK1 and WNK4), identified as hyperactive in the hereditary disease pseudohypoaldosteronism type 2, are responsible for activation of NCC and consequent hypokalemia and hypertension. WNK4, highly expressed in DCT, activates the SPAK/OSR1 kinases, which phosphorylate NCC and other regulatory proteins and transporters in the distal nephron. WNK4 works as a chloride sensor through a Cl- binding site, which acts as an on/off switch at this kinase in response to changes of basolateral membrane electrical potential, the driving force of cellular Cl- efflux. High intracellular Cl- in hyperkalemia decreases NCC phosphorylation and low intracellular Cl- in hypokalemia increases NCC phosphorylation and activity, which makes plasma K+ concentration a central modulator of NCC and of K+ secretion. The WNK4 phosphorylation by cSrc or SGK1, activated by angiotensin II or aldosterone, respectively, is another relevant mechanism of NCC, ENaC, and ROMK modulation in states such as volume reduction, hyperkalemia, and hypokalemia. Loss of NCC function induces upregulation of electroneutral NaCl reabsorption by type B intercalated cells through the combined activity of pendrin and NDCBE, as demonstrated in double knockout mice (KO) animal models, Ncc/pendrin or Ncc/NDCBE. The analysis of ks-Nedd-4-2 KO animal models introduced the modulation of NEDD4-2 by intracellular Mg2+ activity as an important regulator of NCC, explaining the thiazide-induced persistent hypokalemia.
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Affiliation(s)
- E.A. Gallafassi
- Faculdade Israelita de Ciências da Saúde Albert Einstein, São Paulo, SP, Brasil
| | - M.B. Bezerra
- Faculdade Israelita de Ciências da Saúde Albert Einstein, São Paulo, SP, Brasil
| | - N.A. Rebouças
- Faculdade Israelita de Ciências da Saúde Albert Einstein, São Paulo, SP, Brasil
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Morrison AR. Magnesium Homeostasis: Lessons from Human Genetics. Clin J Am Soc Nephrol 2023; 18:01277230-990000000-00067. [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 01/20/2023] [Indexed: 02/02/2023]
Abstract
Mg2+, the fourth most abundant cation in the body, serves as a co-factor for about 600 cellular enzymes. One third of ingested Mg2+ is absorbed from the gut through a saturable transcellular process and a concentration-dependent paracellular process. Absorbed Mg2+ is excreted by the kidney and maintains serum Mg2+ within a narrow range of 0.7 to 1.25 mmol/L. The reabsorption of Mg2+ 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 Mg2+ 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 Mg2+ 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 MO, 63110 USA
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Garg D, Mohammad S, Shukla A, Sharma S. Genetic Links to Episodic Movement Disorders: Current Insights. Appl Clin Genet 2023; 16:11-30. [PMID: 36883047 PMCID: PMC9985884 DOI: 10.2147/tacg.s363485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Accepted: 02/24/2023] [Indexed: 03/05/2023] Open
Abstract
Episodic or paroxysmal movement disorders (PxMD) are conditions, which occur episodically, are transient, usually have normal interictal periods, and are characterized by hyperkinetic disorders, including ataxia, chorea, dystonia, and ballism. Broadly, these comprise paroxysmal dyskinesias (paroxysmal kinesigenic and non-kinesigenic dyskinesia [PKD/PNKD], paroxysmal exercise-induced dyskinesias [PED]) and episodic ataxias (EA) types 1-9. Classification of paroxysmal dyskinesias has traditionally been clinical. However, with advancement in genetics and the discovery of the molecular basis of several of these disorders, it is becoming clear that phenotypic pleiotropy exists, that is, the same variant may give rise to a variety of phenotypes, and the classical understanding of these disorders requires a new paradigm. Based on molecular pathogenesis, paroxysmal disorders are now categorized as synaptopathies, transportopathies, channelopathies, second-messenger related disorders, mitochondrial or others. A genetic paradigm also has an advantage of identifying potentially treatable disorders, such as glucose transporter 1 deficiency syndromes, which necessitates a ketogenic diet, and ADCY5-related disorders, which may respond to caffeine. Clues for a primary etiology include age at onset below 18 years, presence of family history and fixed triggers and attack duration. Paroxysmal movement disorder is a network disorder, with both the basal ganglia and the cerebellum implicated in pathogenesis. Abnormalities in the striatal cAMP turnover pathway may also be contributory. Although next-generation sequencing has restructured the approach to paroxysmal movement disorders, the genetic underpinnings of several entities remain undiscovered. As more genes and variants continue to be reported, these will lead to enhanced understanding of pathophysiological mechanisms and precise treatment.
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Affiliation(s)
- Divyani Garg
- Department of Neurology, All India Institute of Medical Sciences, New Delhi, India
| | - Shekeeb Mohammad
- Kids Neuroscience Centre, The Children's Hospital at Westmead, Faculty of Medicine and Health, University of Sydney, Sydney, New South Wales, Australia.,TY Nelson Department of Neurology and Neurosurgery, The Children's Hospital at Westmead, The University of Sydney, Westmead, New South Wales, Australia
| | - Anju Shukla
- Department of Medical Genetics, Kasturba Medical College and Hospital, Manipal, India
| | - Suvasini Sharma
- Department of Pediatrics (Neurology Division), Lady Hardinge Medical College and Kalawati Saran Hospital, New Delhi, India
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Abstract
PURPOSE OF REVIEW Gitelman syndrome is a recessive salt-wasting disorder characterized by hypomagnesemia, hypokalemia, metabolic alkalosis and hypocalciuria. The majority of patients are explained by mutations and deletions in the SLC12A3 gene, encoding the Na+-Cl--co-transporter (NCC). Recently, additional genetic causes of Gitelman-like syndromes have been identified that should be considered in genetic screening. This review aims to provide a comprehensive overview of the clinical, genetic and mechanistic aspects of Gitelman(-like) syndromes. RECENT FINDINGS Disturbed Na+ reabsorption in the distal convoluted tubule (DCT) is associated with hypomagnesemia and hypokalemic alkalosis. In Gitelman syndrome, loss-of-function mutations in SLC12A3 cause impaired NCC-mediated Na+ reabsorption. In addition, patients with mutations in CLCKNB, KCNJ10, FXYD2 or HNF1B may present with a similar phenotype, as these mutations indirectly reduce NCC activity. Furthermore, genetic investigations of patients with Na+-wasting tubulopathy have resulted in the identification of pathogenic variants in MT-TI, MT-TF, KCNJ16 and ATP1A1. These novel findings highlight the importance of cell metabolism and basolateral membrane potential for Na+ reabsorption in the DCT. SUMMARY Altogether, these findings extend the genetic spectrum of Gitelman-like electrolyte alterations. Genetic testing of patients with hypomagnesemia and hypokalemia should cover a panel of genes involved in Gitelman-like syndromes, including the mitochondrial genome.
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Affiliation(s)
- Karl P Schlingmann
- Department of General Pediatrics, University Children's Hospital, Münster, Germany
| | - Jeroen H F de Baaij
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
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Tseng MH, Yang SS, Sung CC, Ding JJ, Hsu YJ, Chu SM, Lin SH. Novel CNNM2 Mutation Responsible for Autosomal-Dominant Hypomagnesemia With Seizure. Front Genet 2022; 13:875013. [PMID: 35846113 PMCID: PMC9277586 DOI: 10.3389/fgene.2022.875013] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2022] [Accepted: 04/27/2022] [Indexed: 12/04/2022] Open
Abstract
CNNM2 is primarily expressed in the brain and distal convoluted tubule (DCT) of the kidney. Mutations in CNNM2 have been reported to cause hypomagnesemia, seizure, and intellectual disability (HSMR) syndrome. However, the clinical and functional effect of CNNM2 mutations remains incompletely understood. We report our clinical encounter with a 1-year-old infant with HSMR features. Mutation screening for this trio family was performed using next-generation sequencing (NGS)-based whole exome sequencing (WES) with the identified mutation verified by Sanger sequencing. We identified a de novo heterozygous mutation c.G1439T (R480L) in the essential cystathionine β-synthase (CBS) domain of CNNM2 encoding CNNM2 (cyclin M2) without any other gene mutations related to hypomagnesemia. The amino acid involved in this missense mutation was conserved in different species. It was also found to be pathogenic based on the different software prediction models and ACGME criteria. In vitro studies revealed a higher expression of the CNNM2-R480L mutant protein compared to that of the wild-type CNNM2. Like the CNNM2-wild type, proper localization of CNNM2-R480L was shown on immunocytochemistry images. The Mg2+ efflux assay in murine DCT (mDCT) cells revealed a significant increase in intracellular Mg2+ green in CNNM2-R480L compared to that in CNNM2-WT. By using a simulation model, we illustrate that the R480L mutation impaired the interaction between CNNM2 and ATP-Mg2+. We propose that this novel R480L mutation in the CNNM2 gene led to impaired binding between Mg2+-ATP and CNNM2 and diminished Mg2+ efflux, manifesting clinically as refractory hypomagnesemia.
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Affiliation(s)
- Min-Hua Tseng
- Division of Nephrology, Department of Pediatrics, Chang Gung Memorial Hospital and Chang Gung University, Taoyuan, Taiwan.,Department of Pediatrics, Xiamen Chang Gung Hospital, Ximen, China
| | - Sung-Sen Yang
- Division of Nephrology, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
| | - Chih-Chien Sung
- Division of Nephrology, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
| | - Jhao-Jhuang Ding
- Department of Pediatrics, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
| | - Yu-Juei Hsu
- Division of Nephrology, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
| | - Shih-Ming Chu
- Division of Neonatology, Department of Pediatrics, Chang Gung Memorial Hospital and Chang Gung University, Taoyuan, Taiwan
| | - Shih-Hua Lin
- Division of Nephrology, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
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Gaouaoui-Azouaou H, L'Homme B, Benadjaoud MA, Sache-Aloui A, Granger R, Voyer F, Lestaevel P, Gruel G, Caire-Maurisier F, Crambes C, Dare-Doyen S, Benderitter M, Souidi M. Protection and safety of a repeated dosage of KI for iodine thyroid blocking during pregnancy. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2022; 42:011512. [PMID: 34700314 DOI: 10.1088/1361-6498/ac336e] [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: 09/07/2021] [Accepted: 10/26/2021] [Indexed: 06/13/2023]
Abstract
In case of nuclear power plant accidents resulting in the release of radioactive iodine (131I) in large amounts, a single intake of stable iodine is recommended in order to prevent131I fixation to the thyroid gland. However, in situations of prolonged exposure to131I (e.g. Fukushima-Daiichi natural and nuclear disaster), repetitive administration of iodine may be necessary to ensure adequate protection, with acceptable safety in vulnerable populations including pregnant women. Here we conducted toxicological studies on adult rats progeny following prolonged exposure to potassium iodide (KI)in utero. Pregnant Wistar rats were treated with 1 mg kg d-1KI or saline water for 2 or 4 d either between gestation days gestational day (GD) GD 9-12, or GD13-16. Plasma samples from the progeny were tested 30 d post-weaning for clinical biochemistry, thyroid hormones, and anti-thyroid antibody levels. Thyroid and brain were collected for gene expression analysis. The hormonal status was similar for the mothers in all experimental conditions. In the offspring, while thyroid-stimulating hormone and anti-thyroid peroxidase (anti-TPO) antibody levels were similar in all groups, a significant increase of FT3 and FT4 levels was observed in GD9-GD10 and in GD13-GD14 animals treated for 2 d, respectively. In addition, FT4 levels were mildly decreased in 4 d treated GD13-16 individuals. Moreover, a significant decrease in the expression level of thyroid genes involved in iodide metabolism, TPO and apical iodide transporter, was observed in GD13-GD14 animals treated for 2 d. We conclude that repeated KI administration for 2-4 d during gestation did not induce strong thyroid toxicity.
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Affiliation(s)
- Hayat Gaouaoui-Azouaou
- Institut de radioprotection et de sûreté Nucléaire (IRSN), PSE-SANTE, 92290 Fontenay-aux-Roses, France
| | - Bruno L'Homme
- Institut de radioprotection et de sûreté Nucléaire (IRSN), PSE-SANTE, 92290 Fontenay-aux-Roses, France
| | - Mohamed Amine Benadjaoud
- Institut de radioprotection et de sûreté Nucléaire (IRSN), PSE-SANTE, 92290 Fontenay-aux-Roses, France
| | - Amandine Sache-Aloui
- Institut de radioprotection et de sûreté Nucléaire (IRSN), PSE-SANTE, 92290 Fontenay-aux-Roses, France
| | - Romain Granger
- Institut de radioprotection et de sûreté Nucléaire (IRSN), PSE-SANTE, 92290 Fontenay-aux-Roses, France
| | - Frederic Voyer
- Institut de radioprotection et de sûreté Nucléaire (IRSN), PSE-SANTE, 92290 Fontenay-aux-Roses, France
| | - Philippe Lestaevel
- Institut de radioprotection et de sûreté Nucléaire (IRSN), PSE-SANTE, 92290 Fontenay-aux-Roses, France
| | - Gaëtan Gruel
- Institut de radioprotection et de sûreté Nucléaire (IRSN), PSE-SANTE, 92290 Fontenay-aux-Roses, France
| | - François Caire-Maurisier
- Pharmacie Centrale des Armées, Direction des Approvisionnement en produits de santé des armées, 45404 Fleury-les Aubrais, France
| | - Caroline Crambes
- Pharmacie Centrale des Armées, Direction des Approvisionnement en produits de santé des armées, 45404 Fleury-les Aubrais, France
| | - Stephanie Dare-Doyen
- Institut de radioprotection et de sûreté Nucléaire (IRSN), PSE-SANTE, 92290 Fontenay-aux-Roses, France
| | - Marc Benderitter
- Institut de radioprotection et de sûreté Nucléaire (IRSN), PSE-SANTE, 92290 Fontenay-aux-Roses, France
| | - Maâmar Souidi
- Institut de radioprotection et de sûreté Nucléaire (IRSN), PSE-SANTE, 92290 Fontenay-aux-Roses, France
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Reyes JV, Medina PMB. Renal calcium and magnesium handling in Gitelman syndrome. Am J Transl Res 2022; 14:1-19. [PMID: 35173827 PMCID: PMC8829599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 11/24/2021] [Indexed: 06/14/2023]
Abstract
Gitelman syndrome (GS) is an autosomal recessive salt-losing tubulopathy caused by biallelic inactivating mutations in the SLC12A3 gene. This gene encodes the thiazide-sensitive sodium-chloride cotransporter (NCC) which is exclusively expressed in the distal convoluted tubules (DCT). GS patients classically present with hypokalemic metabolic alkalosis with hypocalciuria and hypomagnesemia. While hypokalemia and metabolic alkalosis are easily explained by effects of the genotypic defect in GS, the mechanisms by which hypomagnesemia and hypocalciuria develop in GS are poorly understood. In this review, we aim to achieve three major objectives. First, present a concise discussion about current understanding on physiologic calcium and magnesium handling in the DCT. Second, integrate expression data from studies on calciotropic and magnesiotropic proteins relevant to the GS disease state. Lastly, provide insights into the possible mechanisms of calcium-magnesium crosstalk relating to the co-occurrence of hypocalciuria and hypomagnesemia in GS models. Our analyses highlight specific areas of study that are valuable in elucidating possible molecular pathways of hypocalciuria and hypomagnesemia in GS.
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Affiliation(s)
- Jeremiah V Reyes
- Biological Models Laboratory, Department of Biochemistry and Molecular Biology, College of Medicine, University of the Philippines Manila Ermita, Manila 1000, Philippines
| | - Paul Mark B Medina
- Biological Models Laboratory, Department of Biochemistry and Molecular Biology, College of Medicine, University of the Philippines Manila Ermita, Manila 1000, Philippines
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13
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Grigore TV, Zuidscherwoude M, Witasp A, Barany P, Wernerson A, Bruchfeld A, Xu H, Olauson H, Hoenderop J. Fibroblast growth factor 23 is independently associated with renal magnesium handling in patients with chronic kidney disease. Front Endocrinol (Lausanne) 2022; 13:1046392. [PMID: 36699036 PMCID: PMC9869122 DOI: 10.3389/fendo.2022.1046392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Accepted: 11/28/2022] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND Disturbances in magnesium homeostasis are common in patients with chronic kidney disease (CKD) and are associated with increased mortality. The kidney is a key organ in maintaining normal serum magnesium concentrations. To this end, fractional excretion of magnesium (FEMg) increases as renal function declines. Despite recent progress, the hormonal regulation of renal magnesium handling is incompletely understood. Fibroblast Growth Factor 23 (FGF23) is a phosphaturic hormone that has been linked to renal magnesium handling. However, it has not yet been reported whether FGF23 is associated with renal magnesium handling in CKD patients. METHODS The associations between plasma FGF23 levels, plasma and urine magnesium concentrations and FEMg was investigated in a cross-sectional cohort of 198 non-dialysis CKD patients undergoing renal biopsy. RESULTS FGF23 was significantly correlated with FEMg (Pearson's correlation coefficient = 0.37, p<0.001) and urinary magnesium (-0.14, p=0.04), but not with plasma magnesium. The association between FGF23 and FEMg remained significant after adjusting for potential confounders, including estimated glomerular filtration rate (eGFR), parathyroid hormone and 25-hydroxyvitamin D. CONCLUSIONS We report that plasma FGF23 is independently associated with measures of renal magnesium handling in a cohort of non-dialysis CKD patients. A potential causal relationship should be investigated in future studies.
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Affiliation(s)
- Teodora V. Grigore
- Radboud Institute for Molecular Life Sciences, Department of Physiology, Radboudumc, Nijmegen, Netherlands
| | - Malou Zuidscherwoude
- Radboud Institute for Molecular Life Sciences, Department of Physiology, Radboudumc, Nijmegen, Netherlands
| | - Anna Witasp
- Karolinska Institutet, Division of Renal Medicine, Department of Clinical Science, Intervention and Technology, Stockholm, Sweden
| | - Peter Barany
- Karolinska Institutet, Division of Renal Medicine, Department of Clinical Science, Intervention and Technology, Stockholm, Sweden
| | - Annika Wernerson
- Karolinska Institutet, Division of Renal Medicine, Department of Clinical Science, Intervention and Technology, Stockholm, Sweden
| | - Annette Bruchfeld
- Karolinska Institutet, Division of Renal Medicine, Department of Clinical Science, Intervention and Technology, Stockholm, Sweden
- Linköpings universitet Hälsouniversitetet, Department of Health, Medicine and Caring Sciences, Linköping, Sweden
| | - Hong Xu
- Karolinska Institutet, Division of Clinical Geriatrics, Department of Neurobiology, Department of Care Sciences and Society, Stockholm, Sweden
| | - Hannes Olauson
- Karolinska Institutet, Division of Renal Medicine, Department of Clinical Science, Intervention and Technology, Stockholm, Sweden
| | - Joost Hoenderop
- Radboud Institute for Molecular Life Sciences, Department of Physiology, Radboudumc, Nijmegen, Netherlands
- *Correspondence: Joost Hoenderop,
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14
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Huang Y, Qi L, Kogiso M, Du Y, Braun FK, Zhang H, Huang LF, Xiao S, Teo WY, Lindsay H, Zhao S, Baxter P, Su JMF, Adesina A, Yang J, Brabetz S, Kool M, Pfister SM, Chintagumpala M, Perlaky L, Wang Z, Zhou Y, Man TK, Li XN. Spatial Dissection of Invasive Front from Tumor Mass Enables Discovery of Novel microRNA Drivers of Glioblastoma Invasion. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:e2101923. [PMID: 34719887 PMCID: PMC8655179 DOI: 10.1002/advs.202101923] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Revised: 09/15/2021] [Indexed: 06/13/2023]
Abstract
Diffuse invasion is the primary cause of treatment failure of glioblastoma (GBM). Previous studies on GBM invasion have long been forced to use the resected tumor mass cells. Here, a strategy to reliably isolate matching pairs of invasive (GBMINV ) and tumor core (GBMTC ) cells from the brains of 6 highly invasive patient-derived orthotopic models is described. Direct comparison of these GBMINV and GBMTC cells reveals a significantly elevated invasion capacity in GBMINV cells, detects 23/768 miRNAs over-expressed in the GBMINV cells (miRNAINV ) and 22/768 in the GBMTC cells (miRNATC ), respectively. Silencing the top 3 miRNAsINV (miR-126, miR-369-5p, miR-487b) successfully blocks invasion of GBMINV cells in vitro and in mouse brains. Integrated analysis with mRNA expression identifies miRNAINV target genes and discovers KCNA1 as the sole common computational target gene of which 3 inhibitors significantly suppress invasion in vitro. Furthermore, in vivo treatment with 4-aminopyridine (4-AP) effectively eliminates GBM invasion and significantly prolongs animal survival times (P = 0.035). The results highlight the power of spatial dissection of functionally accurate GBMINV and GBMTC cells in identifying novel drivers of GBM invasion and provide strong rationale to support the use of biologically accurate starting materials in understanding cancer invasion and metastasis.
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Affiliation(s)
- Yulun Huang
- Department of Neurosurgery, Dushu Lake Hospital, Soochow University, Suzhou, 205124, China
- Department of Neurosurgery and Brain and Nerve Research Laboratory, the First Affiliated Hospital, Soochow University, Suzhou, 215007, China
- Texas Children's Cancer Center, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Lin Qi
- Texas Children's Cancer Center, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, 77030, USA
- Program of Precision Medicine PDOX Modeling of Pediatric Tumors, Ann & Robert H. Lurie Children's Hospital of Chicago, Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, IL, 60611, USA
- Department of Pharmacology, School of Medicine, Sun Yat-Sen University, Shenzhen, 518107, China
| | - Mari Kogiso
- Texas Children's Cancer Center, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Yuchen Du
- Texas Children's Cancer Center, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, 77030, USA
- Program of Precision Medicine PDOX Modeling of Pediatric Tumors, Ann & Robert H. Lurie Children's Hospital of Chicago, Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, IL, 60611, USA
| | - Frank K Braun
- Texas Children's Cancer Center, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Huiyuan Zhang
- Texas Children's Cancer Center, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, 77030, USA
| | - L Frank Huang
- Department of Systems Medicine and Bioegineering, Houston Methodist Hospital Research Institute and Cancer Center, Weill Cornell Medicine, Houston, TX, 77030, USA
- Division of Experimental Hematology and Cancer Biology, Brain Tumor Center, Cincinnati Children's Hospital Medical Center, Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, United States, 45229, United States
| | - Sophie Xiao
- Program of Precision Medicine PDOX Modeling of Pediatric Tumors, Ann & Robert H. Lurie Children's Hospital of Chicago, Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, IL, 60611, USA
| | - Wan-Yee Teo
- Humphrey Oei Institute of Cancer Research, National Cancer Center Singapore, Singapore, 169610, Singapore
| | - Holly Lindsay
- Texas Children's Cancer Center, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Sibo Zhao
- Texas Children's Cancer Center, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Patricia Baxter
- Texas Children's Cancer Center, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Jack M F Su
- Texas Children's Cancer Center, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Adekunle Adesina
- Department of Pathology, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Jianhua Yang
- Texas Children's Cancer Center, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Sebastian Brabetz
- Hopp Children's Cancer Center (KiTZ), Heidelberg, 69120, Germany
- Division of Pediatric Neuro-oncology, German Cancer Research Center (DKFZ) and German Cancer Consortium (DKTK), Heidelberg, 69120, Germany
| | - Marcel Kool
- Hopp Children's Cancer Center (KiTZ), Heidelberg, 69120, Germany
- Division of Pediatric Neuro-oncology, German Cancer Research Center (DKFZ) and German Cancer Consortium (DKTK), Heidelberg, 69120, Germany
| | - Stefan M Pfister
- Hopp Children's Cancer Center (KiTZ), Heidelberg, 69120, Germany
- Division of Pediatric Neuro-oncology, German Cancer Research Center (DKFZ) and German Cancer Consortium (DKTK), Heidelberg, 69120, Germany
- Department of Pediatric Hematology and Oncology, Heidelberg University Hospital, Heidelberg, 69120, Germany
| | - Murali Chintagumpala
- Texas Children's Cancer Center, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Laszlo Perlaky
- Texas Children's Cancer Center, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Zhong Wang
- Department of Neurosurgery and Brain and Nerve Research Laboratory, the First Affiliated Hospital, Soochow University, Suzhou, 215007, China
| | - Youxin Zhou
- Department of Neurosurgery and Brain and Nerve Research Laboratory, the First Affiliated Hospital, Soochow University, Suzhou, 215007, China
| | - Tsz-Kwong Man
- Texas Children's Cancer Center, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Xiao-Nan Li
- Texas Children's Cancer Center, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, 77030, USA
- Program of Precision Medicine PDOX Modeling of Pediatric Tumors, Ann & Robert H. Lurie Children's Hospital of Chicago, Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, IL, 60611, USA
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15
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Claverie-Martin F, Perdomo-Ramirez A, Garcia-Nieto V. Hereditary kidney diseases associated with hypomagnesemia. Kidney Res Clin Pract 2021; 40:512-526. [PMID: 34784661 PMCID: PMC8685365 DOI: 10.23876/j.krcp.21.112] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Accepted: 06/20/2021] [Indexed: 11/04/2022] Open
Abstract
In the kidney, a set of proteins expressed in the epithelial cells of the thick ascending loop of Henle and the distal convoluted tubule directly or indirectly play important roles in the regulation of serum magnesium levels. Magnesium reabsorption in the thick ascending loop of Henle occurs through a passive paracellular pathway, while in the distal convoluted tubule, the final magnesium concentration is established through an active transcellular pathway. The players involved in magnesium reabsorption include proteins with diverse functions including tight junction proteins, cation and anion channels, sodium chloride cotransporter, calcium-sensing receptor, epidermal growth factor, cyclin M2, sodium potassium adenosine triphosphatase subunits, transcription factors, a serine protease, and proteins involved in mitochondrial function. Mutations in the genes that encode these proteins impair their function and cause different rare diseases associated with hypomagnesemia, which may lead to muscle cramps, fatigue, epileptic seizures, intellectual disability, cardiac arrhythmias, and chronic kidney disease. The purpose of this review is to describe the clinical and genetic characteristics of these hereditary kidney diseases and the current research findings on the pathophysiological basis of these diseases.
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Affiliation(s)
- Felix Claverie-Martin
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain
| | - Ana Perdomo-Ramirez
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain
| | - Victor Garcia-Nieto
- Unidad de Nefrología Pediátrica, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain
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16
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Tseng MH, Konrad M, Ding JJ, Lin SH. Clinical and Genetic Approach to Renal Hypomagnesemia. Biomed J 2021; 45:74-87. [PMID: 34767995 PMCID: PMC9133307 DOI: 10.1016/j.bj.2021.11.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 11/01/2021] [Accepted: 11/03/2021] [Indexed: 12/03/2022] Open
Abstract
Magnesium (Mg2+) is an important intracellular cation and essential to maintain cell function including cell proliferation, immunity, cellular energy metabolism, protein and nucleic acid synthesis, and regulation of ion channels. Consequences of hypomagnesemia affecting multiple organs can be in overt or subtle presentations. Besides detailed history and complete physical examination, the assessment of urinary Mg2+ excretion is help to differentiate renal from extra-renal (gastrointestinal, tissue sequestration, and shifting) causes of hypomagnesemia. Renal hypomagnesemia can be caused by an increased glomerular filtration and impaired reabsorption in proximal tubular cells, thick ascending limb of the loop of Henle or distal convoluted tubules. A combination of renal Mg2+ wasting, familial history, age of onset, associated features, and exclusion of acquired etiologies point to inherited forms of renal hypomagnesemia. Based on clinical phenotypes, its definite genetic diagnosis can be simply grouped into specific, uncertain, and unknown gene mutations with a priority of genetic approach methods. An unequivocal molecular diagnosis could allow for prediction of clinical outcome, providing genetic counseling, avoiding unnecessary studies or interventions, and possibly uncovering the pathogenic mechanism. Given numerous identified genes responsible for Mg2+ transport in renal hypomagnesemia over the past two decades, several potential and specific molecular and cellular therapeutic strategies to correct hypomagnesemia are promising.
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Affiliation(s)
- Min-Hua Tseng
- Division of Nephrology, Department of Pediatrics, Chang Gung Memorial Hospital and Chang Gung University, Taoyuan, Taiwan; Department of Pediatrics, Xiamen Chang Gung Hospital, China
| | - Martin Konrad
- Department of General Pediatrics, University Children's Hospital Münster, Münster, Germany
| | - Jhao-Jhuang Ding
- Department of Pediatrics, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
| | - Shih-Hua Lin
- Division of Nephrology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
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17
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Ellison DH, Maeoka Y, McCormick JA. Molecular Mechanisms of Renal Magnesium Reabsorption. J Am Soc Nephrol 2021; 32:2125-2136. [PMID: 34045316 PMCID: PMC8729834 DOI: 10.1681/asn.2021010042] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 04/28/2021] [Accepted: 05/01/2021] [Indexed: 02/04/2023] Open
Abstract
Magnesium is an essential cofactor in many cellular processes, and aberrations in magnesium homeostasis can have life-threatening consequences. The kidney plays a central role in maintaining serum magnesium within a narrow range (0.70-1.10 mmol/L). Along the proximal tubule and thick ascending limb, magnesium reabsorption occurs via paracellular pathways. Members of the claudin family form the magnesium pores in these segments, and also regulate magnesium reabsorption by adjusting the transepithelial voltage that drives it. Along the distal convoluted tubule transcellular reabsorption via heteromeric TRPM6/7 channels predominates, although paracellular reabsorption may also occur. In this segment, the NaCl cotransporter plays a critical role in determining transcellular magnesium reabsorption. Although the general machinery involved in renal magnesium reabsorption has been identified by studying genetic forms of magnesium imbalance, the mechanisms regulating it are poorly understood. This review discusses pathways of renal magnesium reabsorption by different segments of the nephron, emphasizing newer findings that provide insight into regulatory process, and outlining critical unanswered questions.
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Affiliation(s)
- David H. Ellison
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon,Veterans Affairs Portland Healthcare System, Portland, Oregon
| | - Yujiro Maeoka
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - James A. McCormick
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
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18
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Meserve JH, Nelson JC, Marsden KC, Hsu J, Echeverry FA, Jain RA, Wolman MA, Pereda AE, Granato M. A forward genetic screen identifies Dolk as a regulator of startle magnitude through the potassium channel subunit Kv1.1. PLoS Genet 2021; 17:e1008943. [PMID: 34061829 PMCID: PMC8195410 DOI: 10.1371/journal.pgen.1008943] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 06/11/2021] [Accepted: 05/04/2021] [Indexed: 11/19/2022] Open
Abstract
The acoustic startle response is an evolutionarily conserved avoidance behavior. Disruptions in startle behavior, particularly startle magnitude, are a hallmark of several human neurological disorders. While the neural circuitry underlying startle behavior has been studied extensively, the repertoire of genes and genetic pathways that regulate this locomotor behavior has not been explored using an unbiased genetic approach. To identify such genes, we took advantage of the stereotypic startle behavior in zebrafish larvae and performed a forward genetic screen coupled with whole genome analysis. We uncovered mutations in eight genes critical for startle behavior, including two genes encoding proteins associated with human neurological disorders, Dolichol kinase (Dolk), a broadly expressed regulator of the glycoprotein biosynthesis pathway, and the potassium Shaker-like channel subunit Kv1.1. We demonstrate that Kv1.1 and Dolk play critical roles in the spinal cord to regulate movement magnitude during the startle response and spontaneous swim movements. Moreover, we show that Kv1.1 protein is mislocalized in dolk mutants, suggesting they act in a common genetic pathway. Combined, our results identify a diverse set of eight genes, all associated with human disorders, that regulate zebrafish startle behavior and reveal a previously unappreciated role for Dolk and Kv1.1 in regulating movement magnitude via a common genetic pathway.
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Affiliation(s)
- Joy H. Meserve
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Jessica C. Nelson
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Kurt C. Marsden
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Jerry Hsu
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Fabio A. Echeverry
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Roshan A. Jain
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Marc A. Wolman
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Alberto E. Pereda
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Michael Granato
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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19
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Downie ML, Lopez Garcia SC, Kleta R, Bockenhauer D. Inherited Tubulopathies of the Kidney: Insights from Genetics. Clin J Am Soc Nephrol 2021; 16:620-630. [PMID: 32238367 PMCID: PMC8092065 DOI: 10.2215/cjn.14481119] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The kidney tubules provide homeostasis by maintaining the external milieu that is critical for proper cellular function. Without homeostasis, there would be no heartbeat, no muscle movement, no thought, sensation, or emotion. The task is achieved by an orchestra of proteins, directly or indirectly involved in the tubular transport of water and solutes. Inherited tubulopathies are characterized by impaired function of one or more of these specific transport molecules. The clinical consequences can range from isolated alterations in the concentration of specific solutes in blood or urine to serious and life-threatening disorders of homeostasis. In this review, we focus on genetic aspects of the tubulopathies and how genetic investigations and kidney physiology have crossfertilized each other and facilitated the identification of these disorders and their molecular basis. In turn, clinical investigations of genetically defined patients have shaped our understanding of kidney physiology.
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Affiliation(s)
- Mallory L. Downie
- Department of Renal Medicine, University College London, London, United Kingdom,Department of Nephrology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
| | - Sergio C. Lopez Garcia
- Department of Renal Medicine, University College London, London, United Kingdom,Department of Nephrology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
| | - Robert Kleta
- Department of Renal Medicine, University College London, London, United Kingdom,Department of Nephrology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
| | - Detlef Bockenhauer
- Department of Renal Medicine, University College London, London, United Kingdom,Department of Nephrology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
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20
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Franken GAC, Müller D, Mignot C, Keren B, Lévy J, Tabet AC, Germanaud D, Tejada MI, Kroes HY, Nievelstein RAJ, Brimble E, Ruzhnikov M, Claverie-Martin F, Szczepańska M, Ćuk M, Latta F, Konrad M, Martínez-Cruz LA, Bindels RJM, Hoenderop JGJ, Schlingmann KP, de Baaij JHF. The phenotypic and genetic spectrum of patients with heterozygous mutations in cyclin M2 (CNNM2). Hum Mutat 2021; 42:473-486. [PMID: 33600043 PMCID: PMC8248058 DOI: 10.1002/humu.24182] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 02/05/2021] [Accepted: 02/10/2021] [Indexed: 12/21/2022]
Abstract
Hypomagnesemia, seizures, and intellectual disability (HSMR) syndrome is a rare disorder caused by mutations in the cyclin M2 (CNNM2) gene. Due to the limited number of cases, extensive phenotype analyses of these patients have not been performed, hindering early recognition of patients. In this study, we established the largest cohort of HSMR to date, aiming to improve recognition and diagnosis of this complex disorder. Eleven novel variants in CNNM2 were identified in nine single sporadic cases and in two families with suspected HSMR syndrome. 25Mg2+ uptake assays demonstrated loss‐of‐function in seven out of nine variants in CNNM2. Interestingly, the pathogenic mutations resulted in decreased plasma membrane expression. The phenotype of those affected by pathogenic CNNM2 mutations was compared with five previously reported cases of HSMR. All patients suffered from hypomagnesemia (0.44–0.72 mmol/L), which could not be fully corrected by Mg2+ supplementation. The majority of patients (77%) experienced generalized seizures and exhibited mild to moderate intellectual disability and speech delay. Moreover, severe obesity was present in most patients (89%). Our data establish hypomagnesemia, seizures, intellectual disability, and obesity as hallmarks of HSMR syndrome. The assessment of these major features offers a straightforward tool for the clinical diagnosis of HSMR.
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Affiliation(s)
- Gijs A C Franken
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Dominik Müller
- Department of Pediatric Gastroenterology, Nephrology and Metabolism, Charité Universitäts Medizin, Berlin, Germany
| | - Cyril Mignot
- Département de Genetique, Centre de Référence Déficiences Intellectuelles de Causes Rares, Assistance Publique Hôpitaux de Paris, Paris, France
| | - Boris Keren
- Département de Génétique, Groupe Hospitalier, Pitié-Salpêtrière, Assistance Publique Hôpitaux de Paris, Paris, France
| | - Jonathan Lévy
- Genetics Department, AP-HP, Robert-Debré University Hospital, Paris, France
| | - Anne-Claude Tabet
- Genetics Department, AP-HP, Robert-Debré University Hospital, Paris, France
| | - David Germanaud
- Pediatric Neurology Department, Centre de Référence Déficiences Intellectuelles de Causes Rares, Service de Neurologie Pédiatrique, Hôpital Robert-Debré, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - María-Isabel Tejada
- Osakidetza Basque Health Service, Cruces University Hospital, Genetics Service and Biocruces Bizkaia Health Research Institute, Barakaldo, Spain.,Spanish Consortium for Research on Rare Diseases (CIBERER), Valencia, Spain
| | - Hester Y Kroes
- Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Rutger A J Nievelstein
- Department of Pediatric Radiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Elise Brimble
- Department of Neurology and Neurological Sciences, Stanford Medicine, Stanford, California, USA
| | - Maria Ruzhnikov
- Department of Neurology and Neurological Sciences, Stanford Medicine, Stanford, California, USA
| | - Felix Claverie-Martin
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain
| | - Maria Szczepańska
- Department of Pediatrics, Medical University of Silesia, Katowice, Poland
| | - Martin Ćuk
- Department of Pediatrics, Children's Hospital Zagreb, Zagreb, Croatia
| | - Femke Latta
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Martin Konrad
- Department of General Pediatrics, University Children's Hospital, Münster, Germany
| | - Luis A Martínez-Cruz
- Structural Biology Unit, Center for Cooperative Research in Biosciences (CIC bioGUNE), Technology Park of Bizkaia, Derio, Spain
| | - René J M Bindels
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Joost G J Hoenderop
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | | | - Jeroen H F de Baaij
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
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21
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Erbaş İM, Altincik SA, Çatli G, Ünüvar T, Özhan B, Abaci A, Anik A. Does fludrocortisone treatment cause hypomagnesemia in children with primary adrenal insufficiency? Turk J Med Sci 2021; 51:231-237. [PMID: 33155789 PMCID: PMC7991856 DOI: 10.3906/sag-2008-167] [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: 08/19/2020] [Accepted: 11/05/2020] [Indexed: 11/18/2022] Open
Abstract
Background/aim Aldosterone is a mineralocorticoid that secreted from adrenal glands and a known factor to increase magnesium excretion by direct and indirect effects on renal tubular cells. Although the frequency of hypomagnesemia was found to be approximately 5% in adult studies, there is no study in the literature investigating the frequency of hypomagnesemia in children by using fludrocortisone, which has a mineralocorticoid activity. Materials and methods A multi-center retrospective study was conducted, including children who were under fludrocortisone treatment for primary adrenal insufficiency and applied to participant pediatric endocrinology outpatient clinics. Results Forty-three patients (58.1% male, 41.9% prepubertal) included in the study, whose median age was 9.18 (0.61-19) years, and the most common diagnosis among the patients was a salt-wasting form of congenital adrenal hyperplasia (67.4%). Mean serum magnesium level was 2.05 (±0.13) mg/dL, and hypomagnesemia was not observed in any of the patients treated with fludrocortisone. None of the patients had increased urinary excretion of magnesium. Conclusion Unlike the studies performed in adults, we could not find any evidence of magnesium wasting effect of fludrocortisone treatment with normal or even high doses in children and adolescents.
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Affiliation(s)
- İbrahim Mert Erbaş
- Department of Pediatric Endocrinology, Faculty of Medicine, Dokuz Eylül University, İzmir, Turkey
| | - Selda Ayça Altincik
- Department of Pediatric Endocrinology, Faculty of Medicine, Pamukkale University, Denizli, Turkey
| | - Gönül Çatli
- Department of Pediatric Endocrinology, Faculty of Medicine, İzmir Kâtip Çelebi University, İzmir, Turkey
| | - Tolga Ünüvar
- Department of Pediatric Endocrinology, Faculty of Medicine, Aydın Adnan Menderes University, Aydın, Turkey
| | - Bayram Özhan
- Department of Pediatric Endocrinology, Faculty of Medicine, Pamukkale University, Denizli, Turkey
| | - Ayhan Abaci
- Department of Pediatric Endocrinology, Faculty of Medicine, Dokuz Eylül University, İzmir, Turkey
| | - Ahmet Anik
- Department of Pediatric Endocrinology, Faculty of Medicine, Aydın Adnan Menderes University, Aydın, Turkey
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22
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Olde Hanhof CJA, Yousef Yengej FA, Rookmaaker MB, Verhaar MC, van der Wijst J, Hoenderop JG. Modeling Distal Convoluted Tubule (Patho)Physiology: An Overview of Past Developments and an Outlook Toward the Future. Tissue Eng Part C Methods 2021; 27:200-212. [PMID: 33544049 DOI: 10.1089/ten.tec.2020.0345] [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] [Indexed: 12/26/2022] Open
Abstract
The kidneys are essential for maintaining electrolyte homeostasis. Blood electrolyte composition is controlled by active reabsorption and secretion processes in dedicated segments of the kidney tubule. Specifically, the distal convoluted tubule (DCT) and connecting tubule are important for regulating the final excretion of sodium, magnesium, and calcium. Studies unravelling the specific function of these segments have greatly improved our understanding of DCT (patho)physiology. Over the years, experimental models used to study the DCT have changed and the field has advanced from early dissection studies with rats and rabbits to the use of various transgenic mouse models. Developments in dissection techniques and cell culture methods have resulted in immortalized mouse DCT cell lines and made it possible to specifically obtain DCT fragments for ex vivo studies. However, we still do not fully understand the complex (patho)physiology of this segment and there is need for advanced human DCT models. Recently, kidney organoids and tubuloids have emerged as new complex cell models that provide excellent opportunities for physiological studies, disease modeling, drug discovery, and even personalized medicine in the future. This review presents an overview of cell models used to study the DCT and provides an outlook on kidney organoids and tubuloids as model for DCT (patho)physiology. Impact statement This study provides a detailed overview of past and future developments on cell models used to study kidney (patho)physiology and specifically the distal convoluted tubule (DCT) segment. Hereby, we highlight the need for an advanced human cell model of this segment and summarize recent advances in the field of kidney organoids and tubuloids with a focus on DCT properties. The findings reported in this review are significant for future developments toward an advanced human model of the DCT that will help to increase our understanding of DCT (patho)physiology.
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Affiliation(s)
- Charlotte J A Olde Hanhof
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Fjodor A Yousef Yengej
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences, Utrecht, The Netherlands.,Department of Nephrology and Hypertension, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Maarten B Rookmaaker
- Department of Nephrology and Hypertension, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Marianne C Verhaar
- Department of Nephrology and Hypertension, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Jenny van der Wijst
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Joost G Hoenderop
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
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23
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Franken GAC, Adella A, Bindels RJM, Baaij JHF. Mechanisms coupling sodium and magnesium reabsorption in the distal convoluted tubule of the kidney. Acta Physiol (Oxf) 2021; 231:e13528. [PMID: 32603001 PMCID: PMC7816272 DOI: 10.1111/apha.13528] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 05/29/2020] [Accepted: 06/22/2020] [Indexed: 02/06/2023]
Abstract
Hypomagnesaemia is a common feature of renal Na+ wasting disorders such as Gitelman and EAST/SeSAME syndrome. These genetic defects specifically affect Na+ reabsorption in the distal convoluted tubule, where Mg2+ reabsorption is tightly regulated. Apical uptake via TRPM6 Mg2+ channels and basolateral Mg2+ extrusion via a putative Na+ -Mg2+ exchanger determines Mg2+ reabsorption in the distal convoluted tubule. However, the mechanisms that explain the high incidence of hypomagnesaemia in patients with Na+ wasting disorders of the distal convoluted tubule are largely unknown. In this review, we describe three potential mechanisms by which Mg2+ reabsorption in the distal convoluted tubule is linked to Na+ reabsorption. First, decreased activity of the thiazide-sensitive Na+ /Cl- cotransporter (NCC) results in shortening of the segment, reducing the Mg2+ reabsorption capacity. Second, the activity of TRPM6 and NCC are determined by common regulatory pathways. Secondary effects of NCC dysregulation such as hormonal imbalance, therefore, might disturb TRPM6 expression. Third, the basolateral membrane potential, maintained by the K+ permeability and Na+ -K+ -ATPase activity, provides the driving force for Na+ and Mg2+ extrusion. Depolarisation of the basolateral membrane potential in Na+ wasting disorders of the distal convoluted tubule may therefore lead to reduced activity of the putative Na+ -Mg2+ exchanger SLC41A1. Elucidating the interconnections between Mg2+ and Na+ transport in the distal convoluted tubule is hampered by the currently available models. Our analysis indicates that the coupling of Na+ and Mg2+ reabsorption may be multifactorial and that advanced experimental models are required to study the molecular mechanisms.
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Affiliation(s)
- Gijs A. C. Franken
- Department of Physiology Radboud Institute for Molecular Life SciencesRadboud University Medical Center Nijmegen the Netherlands
| | - Anastasia Adella
- Department of Physiology Radboud Institute for Molecular Life SciencesRadboud University Medical Center Nijmegen the Netherlands
| | - René J. M. Bindels
- Department of Physiology Radboud Institute for Molecular Life SciencesRadboud University Medical Center Nijmegen the Netherlands
| | - Jeroen H. F. Baaij
- Department of Physiology Radboud Institute for Molecular Life SciencesRadboud University Medical Center Nijmegen the Netherlands
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24
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Workeneh BT, Uppal NN, Jhaveri KD, Rondon-Berrios H. Hypomagnesemia in the Cancer Patient. KIDNEY360 2020; 2:154-166. [PMID: 35368816 PMCID: PMC8785729 DOI: 10.34067/kid.0005622020] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 11/11/2020] [Indexed: 02/04/2023]
Abstract
Hypomagnesemia is a common medical problem that contributes to the morbidity and mortality of patients with cancer. This review summarizes magnesium physiology and highlights the mechanisms underlying magnesium disturbances due to cancer and cancer treatment. The causes of hypomagnesemia can be categorized according to the pathophysiologic mechanism: decreased intake, transcellular shift, gastrointestinal losses, and kidney losses. Patients with cancer are at risk for opportunistic infections, frequently experience cardiovascular complications, and often receive classes of medications that cause or exacerbate hypomagnesemia. Also, cancer-specific therapies are responsible for hypomagnesemia, including platinum-based chemotherapy, anti-EGF receptor mAbs, human EGF receptor-2 target inhibitors (HER2), and calcineurin inhibitors. Urinary indices, such as the fractional excretion of magnesium, can provide useful information about the etiology. The management of hypomagnesemia depends on the magnitude of hypomagnesemia and the underlying cause. We recommended checking serum magnesium at the beginning of treatment and as part of routine monitoring throughout cancer treatment. Opportunities exist for potential research and practice improvement, including further characterization of hypomagnesemia regarding the clinical effect on cancer outcomes, preventing hypomagnesemia in patients receiving high-risk anticancer agents, and developing effective therapeutic strategies.
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Affiliation(s)
- Biruh T. Workeneh
- Section of Nephrology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Nupur N. Uppal
- Division of Kidney Diseases and Hypertension, Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, Northwell Health, Great Neck, New York
| | - Kenar D. Jhaveri
- Division of Kidney Diseases and Hypertension, Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, Northwell Health, Great Neck, New York
| | - Helbert Rondon-Berrios
- Renal-Electrolyte Division, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
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25
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Maeoka Y, McCormick JA. NaCl cotransporter activity and Mg 2+ handling by the distal convoluted tubule. Am J Physiol Renal Physiol 2020; 319:F1043-F1053. [PMID: 33135481 DOI: 10.1152/ajprenal.00463.2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The genetic disease Gitelman syndrome, knockout mice, and pharmacological blockade with thiazide diuretics have revealed that reduced activity of the NaCl cotransporter (NCC) promotes renal Mg2+ wasting. NCC is expressed along the distal convoluted tubule (DCT), and its activity determines Mg2+ entry into DCT cells through transient receptor potential channel subfamily M member 6 (TRPM6). Several other genetic forms of hypomagnesemia lower the drive for Mg2+ entry by inhibiting activity of basolateral Na+-K+-ATPase, and reduced NCC activity may do the same. Lower intracellular Mg2+ may promote further Mg2+ loss by directly decreasing activity of Na+-K+-ATPase. Lower intracellular Mg2+ may also lower Na+-K+-ATPase indirectly by downregulating NCC. Lower NCC activity also induces atrophy of DCT cells, decreasing the available number of TRPM6 channels. Conversely, a mouse model with increased NCC activity was recently shown to display normal Mg2+ handling. Moreover, recent studies have identified calcineurin and uromodulin (UMOD) as regulators of both NCC and Mg2+ handling by the DCT. Calcineurin inhibitors paradoxically cause hypomagnesemia in a state of NCC activation, but this may be related to direct effects on TRPM6 gene expression. In Umod-/- mice, the cause of hypomagnesemia may be partly due to both decreased NCC expression and lower TRPM6 expression on the cell surface. This mini-review discusses these new findings and the possible role of altered Na+ flux through NCC and ultimately Na+-K+-ATPase in Mg2+ reabsorption by the DCT.
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Affiliation(s)
- Yujiro Maeoka
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - James A McCormick
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
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26
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Imenez Silva PH, Wagner CA. Potassium channels in control of renal function. Kidney Int 2020; 97:253-255. [PMID: 31980072 DOI: 10.1016/j.kint.2019.10.029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 10/22/2019] [Accepted: 10/24/2019] [Indexed: 11/18/2022]
Abstract
Potassium channels are important to control membrane potential and drive epithelial transport processes. In this issue of Kidney International, Bignon et al. report the role of the Kir4.2 K+-channel, localized at the basolateral membrane of proximal tubules, in the reabsorption of bicarbonate and the modulation of renal ammoniagenesis. The findings have implications for our understanding of how the kidney reacts to hypokalemia, an acid load, and the metabolic acidosis of patients with advanced stages of chronic kidney disease.
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Affiliation(s)
- Pedro H Imenez Silva
- Institute of Physiology, University of Zurich, Zurich, Switzerland; National Center of Competence in Research NCCR Kidney.CH, Switzerland
| | - Carsten A Wagner
- Institute of Physiology, University of Zurich, Zurich, Switzerland; National Center of Competence in Research NCCR Kidney.CH, Switzerland.
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27
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D’Adamo MC, Liantonio A, Rolland JF, Pessia M, Imbrici P. Kv1.1 Channelopathies: Pathophysiological Mechanisms and Therapeutic Approaches. Int J Mol Sci 2020; 21:ijms21082935. [PMID: 32331416 PMCID: PMC7215777 DOI: 10.3390/ijms21082935] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 04/19/2020] [Accepted: 04/20/2020] [Indexed: 12/27/2022] Open
Abstract
Kv1.1 belongs to the Shaker subfamily of voltage-gated potassium channels and acts as a critical regulator of neuronal excitability in the central and peripheral nervous systems. KCNA1 is the only gene that has been associated with episodic ataxia type 1 (EA1), an autosomal dominant disorder characterized by ataxia and myokymia and for which different and variable phenotypes have now been reported. The iterative characterization of channel defects at the molecular, network, and organismal levels contributed to elucidating the functional consequences of KCNA1 mutations and to demonstrate that ataxic attacks and neuromyotonia result from cerebellum and motor nerve alterations. Dysfunctions of the Kv1.1 channel have been also associated with epilepsy and kcna1 knock-out mouse is considered a model of sudden unexpected death in epilepsy. The tissue-specific association of Kv1.1 with other Kv1 members, auxiliary and interacting subunits amplifies Kv1.1 physiological roles and expands the pathogenesis of Kv1.1-associated diseases. In line with the current knowledge, Kv1.1 has been proposed as a novel and promising target for the treatment of brain disorders characterized by hyperexcitability, in the attempt to overcome limited response and side effects of available therapies. This review recounts past and current studies clarifying the roles of Kv1.1 in and beyond the nervous system and its contribution to EA1 and seizure susceptibility as well as its wide pharmacological potential.
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Affiliation(s)
- Maria Cristina D’Adamo
- Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Msida MDS-2080, Malta; (M.C.D.); (M.P.)
| | - Antonella Liantonio
- Department of Pharmacy–Drug Sciences, University of Bari “Aldo Moro”, 70125 Bari, Italy;
| | | | - Mauro Pessia
- Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Msida MDS-2080, Malta; (M.C.D.); (M.P.)
- Department of Physiology, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain Po Box 17666, UAE
| | - Paola Imbrici
- Department of Pharmacy–Drug Sciences, University of Bari “Aldo Moro”, 70125 Bari, Italy;
- Correspondence:
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28
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Clinical Spectrum of KCNA1 Mutations: New Insights into Episodic Ataxia and Epilepsy Comorbidity. Int J Mol Sci 2020; 21:ijms21082802. [PMID: 32316562 PMCID: PMC7215408 DOI: 10.3390/ijms21082802] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 04/14/2020] [Accepted: 04/16/2020] [Indexed: 12/13/2022] Open
Abstract
Mutations in the KCNA1 gene, which encodes voltage-gated Kv1.1 potassium channel α-subunits, cause a variety of human diseases, complicating simple genotype–phenotype correlations in patients. KCNA1 mutations are primarily associated with a rare neurological movement disorder known as episodic ataxia type 1 (EA1). However, some patients have EA1 in combination with epilepsy, whereas others have epilepsy alone. KCNA1 mutations can also cause hypomagnesemia and paroxysmal dyskinesia in rare cases. Why KCNA1 variants are associated with such phenotypic heterogeneity in patients is not yet understood. In this review, literature databases (PubMed) and public genetic archives (dbSNP and ClinVar) were mined for known pathogenic or likely pathogenic mutations in KCNA1 to examine whether patterns exist between mutation type and disease manifestation. Analyses of the 47 deleterious KCNA1 mutations that were identified revealed that epilepsy or seizure-related variants tend to cluster in the S1/S2 transmembrane domains and in the pore region of Kv1.1, whereas EA1-associated variants occur along the whole length of the protein. In addition, insights from animal models of KCNA1 channelopathy were considered, as well as the possible influence of genetic modifiers on disease expressivity and severity. Elucidation of the complex relationship between KCNA1 variants and disease will enable better diagnostic risk assessment and more personalized therapeutic strategies for KCNA1 channelopathy.
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29
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Manville RW, Abbott GW. Isoform-Selective KCNA1 Potassium Channel Openers Built from Glycine. J Pharmacol Exp Ther 2020; 373:391-401. [PMID: 32217768 DOI: 10.1124/jpet.119.264507] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 03/24/2020] [Indexed: 12/18/2022] Open
Abstract
Loss of function of voltage-gated potassium (Kv) channels is linked to a range of lethal or debilitating channelopathies. New pharmacological approaches are warranted to isoform-selectively activate specific Kv channels. One example is KCNA1 Potassium Voltage-Gated Channel Subfamily A Member 1 (KCNA1) (Kv1.1), an archetypal Shaker-type Kv channel, in which loss-of-function mutations cause episodic ataxia type 1 (EA1). EA1 causes constant myokomia and episodic bouts of ataxia and may associate with epilepsy and other disorders. We previously found that the inhibitory neurotransmitter γ-aminobutyric acid and modified versions of glycine directly activate Kv channels within the KCNQ subfamily, a characteristic favored by strong negative electrostatic surface potential near the neurotransmitter carbonyl group. Here, we report that adjusting the number and positioning of fluorine atoms within the fluorophenyl ring of glycine derivatives produces isoform-selective KCNA1 channel openers that are inactive against KCNQ2/3 channels, or even KCNA2, the closest relative of KCNA1. The findings refine our understanding of the molecular basis for KCNQ versus KCNA1 activation and isoform selectivity and constitute, to our knowledge, the first reported isoform-selective KCNA1 opener. SIGNIFICANCE STATEMENT: Inherited loss-of-function gene sequence variants in KCNA1, which encodes the KCNA1 (Kv1.1) voltage-gated potassium channel, cause episodic ataxia type 1 (EA1), a movement disorder also linked to epilepsy and developmental delay. We have discovered several isoform-specific KCNA1-activating small molecules, addressing a notable gap in the field and providing possible lead compounds and a novel chemical space for the development of potential future therapeutic drugs for EA1.
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Affiliation(s)
- Rían W Manville
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California
| | - Geoffrey W Abbott
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California
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30
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Bianchi F, Simoncini C, Brugnoni R, Ricci G, Siciliano G. Neuromuscular tetanic hyperexcitability syndrome associated to a heterozygous Kv1.1 N255D mutation with normal serum magnesium levels. ACTA MYOLOGICA : MYOPATHIES AND CARDIOMYOPATHIES : OFFICIAL JOURNAL OF THE MEDITERRANEAN SOCIETY OF MYOLOGY 2020; 39:36-39. [PMID: 32607479 PMCID: PMC7315896 DOI: 10.36185/2532-1900-007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Accepted: 03/09/2020] [Indexed: 06/11/2023]
Abstract
Mutations of the main voltage-gated K channel members Kv1.1 are linked to several clinical conditions, such as periodic ataxia type 1, myokymia and seizure disorders. Due to their role in active magnesium reabsorption through the renal distal convoluted tubule segment, mutations in the KCNA1 gene encoding for Kv1.1 has been associated with hypomagnesemia with myokymia and tetanic crises. Here we describe a case of a young female patient who came to our attention for a history of muscular spasms, tetanic episodes and muscle weakness, initially misdiagnosed for fibromyalgia. After a genetic screening she was found to be carrier of the c.736A > G (p.Asn255Asp) mutation in KCNA1, previously described in a family with autosomal dominant hypomagnesemia with muscular spasms, myokymia and tetanic episodes. However, our patient has always presented normal serum and urinary magnesium values, whereas she was affected by hypocalcemia. Calcium supplementation gave only partial clinical benefit, with an improvement on tetanic episodes yet without a clinical remission of her spasms, whereas magnesium supplementation worsened her muscular symptomatology.
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Affiliation(s)
- Francesca Bianchi
- Department of Clinical and Experimental Medicine, Neurological Clinic, University of Pisa, Italy
| | - Costanza Simoncini
- Department of Clinical and Experimental Medicine, Neurological Clinic, University of Pisa, Italy
| | - Raffaella Brugnoni
- Neurology IV - Neuroimmunology and Neuromuscular Diseases Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Giulia Ricci
- Department of Clinical and Experimental Medicine, Neurological Clinic, University of Pisa, Italy
| | - Gabriele Siciliano
- Department of Clinical and Experimental Medicine, Neurological Clinic, University of Pisa, Italy
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31
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Groome JR, Bayless-Edwards L. Roles for Countercharge in the Voltage Sensor Domain of Ion Channels. Front Pharmacol 2020; 11:160. [PMID: 32180723 PMCID: PMC7059764 DOI: 10.3389/fphar.2020.00160] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Accepted: 02/07/2020] [Indexed: 12/19/2022] Open
Abstract
Voltage-gated ion channels share a common structure typified by peripheral, voltage sensor domains. Their S4 segments respond to alteration in membrane potential with translocation coupled to ion permeation through a central pore domain. The mechanisms of gating in these channels have been intensely studied using pioneering methods such as measurement of charge displacement across a membrane, sequencing of genes coding for voltage-gated ion channels, and the development of all-atom molecular dynamics simulations using structural information from prokaryotic and eukaryotic channel proteins. One aspect of this work has been the description of the role of conserved negative countercharges in S1, S2, and S3 transmembrane segments to promote sequential salt-bridge formation with positively charged residues in S4 segments. These interactions facilitate S4 translocation through the lipid bilayer. In this review, we describe functional and computational work investigating the role of these countercharges in S4 translocation, voltage sensor domain hydration, and in diseases resulting from countercharge mutations.
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Affiliation(s)
- James R. Groome
- Department of Biological Sciences, Idaho State University, Pocatello, ID, United States
| | - Landon Bayless-Edwards
- Department of Biological Sciences, Idaho State University, Pocatello, ID, United States
- Oregon Health and Sciences University School of Medicine, Portland, OR, United States
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32
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Verdura E, Fons C, Schlüter A, Ruiz M, Fourcade S, Casasnovas C, Castellano A, Pujol A. Complete loss of KCNA1 activity causes neonatal epileptic encephalopathy and dyskinesia. J Med Genet 2019; 57:132-137. [PMID: 31586945 PMCID: PMC7029237 DOI: 10.1136/jmedgenet-2019-106373] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 09/12/2019] [Accepted: 09/15/2019] [Indexed: 11/29/2022]
Abstract
Background Since 1994, over 50 families affected by the episodic ataxia type 1 disease spectrum have been described with mutations in KCNA1, encoding the voltage-gated K+ channel subunit Kv1.1. All of these mutations are either transmitted in an autosomal-dominant mode or found as de novo events. Methods A patient presenting with a severe combination of dyskinesia and neonatal epileptic encephalopathy was sequenced by whole-exome sequencing (WES). A candidate variant was tested using cellular assays and patch-clamp recordings. Results WES revealed a homozygous variant (p.Val368Leu) in KCNA1, involving a conserved residue in the pore domain, close to the selectivity signature sequence for K+ ions (TVGYG). Functional analysis showed that mutant protein alone failed to produce functional channels in homozygous state, while coexpression with wild-type produced no effects on K+ currents, similar to wild-type protein alone. Treatment with oxcarbazepine, a sodium channel blocker, proved effective in controlling seizures. Conclusion This newly identified variant is the first to be reported to act in a recessive mode of inheritance in KCNA1. These findings serve as a cautionary tale for the diagnosis of channelopathies, in which an unreported phenotypic presentation or mode of inheritance for the variant of interest can hinder the identification of causative variants and adequate treatment choice.
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Affiliation(s)
- Edgard Verdura
- Neurometabolic Diseases Laboratory, Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Catalunya, Spain.,Centre for Biomedical Research on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Barcelona, Spain
| | - Carme Fons
- Centre for Biomedical Research on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Barcelona, Spain.,Pediatric Neurology Department, Hospital Sant Joan de Déu, Esplugues de Llobregat, Barcelona, Catalunya, Spain.,Sant Joan de Déu Research Institute (IRSJD), Esplugues de Llobregat, Barcelona, Catalunya, Spain
| | - Agatha Schlüter
- Neurometabolic Diseases Laboratory, Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Catalunya, Spain.,Centre for Biomedical Research on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Barcelona, Spain
| | - Montserrat Ruiz
- Neurometabolic Diseases Laboratory, Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Catalunya, Spain.,Centre for Biomedical Research on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Barcelona, Spain
| | - Stéphane Fourcade
- Neurometabolic Diseases Laboratory, Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Catalunya, Spain.,Centre for Biomedical Research on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Barcelona, Spain
| | - Carlos Casasnovas
- Neurometabolic Diseases Laboratory, Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Catalunya, Spain.,Centre for Biomedical Research on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Barcelona, Spain.,Neuromuscular Unit, Neurology Department, Hospital Universitari de Bellvitge, L'Hospitalet de Llobregat, Barcelona, Catalunya, Spain
| | - Antonio Castellano
- Institute of Biomedicine of Seville (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain.,Medical Physiology and Biophysics Departament, Universidad de Sevilla, Sevilla, Spain
| | - Aurora Pujol
- Neurometabolic Diseases Laboratory, Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Catalunya, Spain .,Centre for Biomedical Research on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Barcelona, Spain.,Catalan Institution of Research and Advanced Studies (ICREA), Barcelona, Catalunya, Spain
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33
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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: 52] [Impact Index Per Article: 10.4] [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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De Gusmao CM, Silveira-Moriyama L. Paroxysmal movement disorders - practical update on diagnosis and management. Expert Rev Neurother 2019; 19:807-822. [PMID: 31353980 DOI: 10.1080/14737175.2019.1648211] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Introduction: Paroxysmal dyskinesias and episodic ataxias are often caused by mutations in genes related to cell membrane and synaptic function. Despite the exponential increase in publications of genetically confirmed cases, management remains largely clinical based on non-systematic evidence. Areas covered: The authors provide a historical and clinical review of the main types of paroxysmal dyskinesias and episodic ataxias, with recommendations for diagnosis and management of patients suffering from these conditions. Expert opinion: After secondary paroxysmal dyskinesias, the most common paroxysmal movement disorders are likely to be PRRT2-associated paroxysmal kinesigenic dyskinesias, which respond well to small doses of carbamazepine, and episodic ataxia type 2, which often responds to acetazolamide. Familial paroxysmal non-kinesigenic dyskinesias are largely caused by mutations in PNKD and have poor response to therapy but improve with age. Exercise-induced dyskinesias are genetically heterogeneous, caused by disorders of glucose transport, mitochondrial function, dopaminergic pathways or neurodegenerative conditions amongst others. GNAO1 and ADCY5 mutations can also cause paroxysmal movement disorders, often in the context of ongoing motor symptoms. Although a therapeutic trial is justified for classic cases and in limited resource settings, genetic testing may help direct initial or rescue therapy. Deep brain stimulation may be an option for severe cases.
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Affiliation(s)
- Claudio M De Gusmao
- Department of Neurology, Harvard Medical School, Boston Children's Hospital , Boston , MA , USA.,Department of Neurology, Universidade Estadual de Campinas (UNICAMP) , São Paulo , Brazil
| | - Laura Silveira-Moriyama
- Department of Neurology, Universidade Estadual de Campinas (UNICAMP) , São Paulo , Brazil.,Education Unit, UCL Institute of Neurology, University College London , London , UK.,Department of Neurology, Hospital Bairral, Fundação Espírita Américo Bairral , Itapira , Brazil
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Yin XM, Lin JH, Cao L, Zhang TM, Zeng S, Zhang KL, Tian WT, Hu ZM, Li N, Wang JL, Guo JF, Wang RX, Xia K, Zhang ZH, Yin F, Peng J, Liao WP, Yi YH, Liu JY, Yang ZX, Chen Z, Mao X, Yan XX, Jiang H, Shen L, Chen SD, Zhang LM, Tang BS. Familial paroxysmal kinesigenic dyskinesia is associated with mutations in the KCNA1 gene. Hum Mol Genet 2019; 27:625-637. [PMID: 29294000 DOI: 10.1093/hmg/ddx430] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Accepted: 12/15/2017] [Indexed: 12/23/2022] Open
Abstract
Paroxysmal kinesigenic dyskinesia (PKD) is a heterogeneous movement disorder characterized by recurrent dyskinesia attacks triggered by sudden movement. PRRT2 has been identified as the first causative gene of PKD. However, it is only responsible for approximately half of affected individuals, indicating that other loci are most likely involved in the etiology of this disorder. To explore the underlying causative gene of PRRT2-negative PKD, we used a combination strategy including linkage analysis, whole-exome sequencing and copy number variations analysis to detect the genetic variants within a family with PKD. We identified a linkage locus on chromosome 12 (12p13.32-12p12.3) and detected a novel heterozygous mutation c.956 T>G (p.319 L>R) in the potassium voltage-gated channel subfamily A member 1, KCNA1. Whole-exome sequencing in another 58 Chinese patients with PKD who lacked mutations in PRRT2 revealed another novel mutation in the KCNA1 gene [c.765 C>A (p.255 N>K)] within another family. Biochemical analysis revealed that the L319R mutant accelerated protein degradation via the proteasome pathway and disrupted membrane expression of the Kv1.1 channel. Electrophysiological examinations in transfected HEK293 cells showed that both the L319R and N255K mutants resulted in reduced potassium currents and respective altered gating properties, with a dominant negative effect on the Kv1.1 wild-type channel. Our study suggests that these mutations in KCNA1 cause the Kv1.1 channel dysfunction, which leads to familial PKD. The current study further extended the genotypic spectrum of this disorder, indicating that Kv1.1 channel dysfunction maybe one of the underlying defects in PKD.
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Affiliation(s)
- Xiao-Meng Yin
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China
| | - Jing-Han Lin
- Department of Neurology, The First Affiliated Hospital of Harbin Medical University, Harbin 150001, China
| | - Li Cao
- Department of Neurology and Institute of Neurology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Tong-Mei Zhang
- Department of Physiology, School of Basic Medicine and Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.,The Institute for Brain Research, Collaborative Innovation Center for Brain Science, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Sheng Zeng
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China
| | - Kai-Lin Zhang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China
| | - Wo-Tu Tian
- Department of Neurology and Institute of Neurology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Zheng-Mao Hu
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan 410008, China
| | - Nan Li
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China.,Key Laboratory of Hunan Province in Neurodegenerative Disorders, Central South University, Changsha, Hunan 410008, China
| | - Jun-Ling Wang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China.,Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan 410008, China.,Key Laboratory of Hunan Province in Neurodegenerative Disorders, Central South University, Changsha, Hunan 410008, China
| | - Ji-Feng Guo
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China.,Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan 410008, China.,National Clinical Research Center for Geriatric Disorders, Central South University, Changsha, Hunan 410008, China.,Key Laboratory of Hunan Province in Neurodegenerative Disorders, Central South University, Changsha, Hunan 410008, China
| | - Ruo-Xi Wang
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan 410008, China.,Institute of Precision Medicine, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China
| | - Kun Xia
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan 410008, China
| | - Zhuo-Hua Zhang
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan 410008, China.,Institute of Precision Medicine, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China.,Department of Neurosciences, School of Medicine, University of South China, Hengyang, Hunan 420001, China
| | - Fei Yin
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China.,Hunan Intellectual and Development Disabilities Research Center, Changsha, Hunan 410008, China
| | - Jing Peng
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China.,Hunan Intellectual and Development Disabilities Research Center, Changsha, Hunan 410008, China
| | - Wei-Ping Liao
- Key Laboratory of Neurogenetics and Channelopathies of Guangdong Province and Ministry of Education of China, Department of Neurology of the Second Affiliated Hospital of Guangzhou Medical University, Institute of Neuroscience, Guangzhou Medical University, Guangzhou 510260, China
| | - Yong-Hong Yi
- Key Laboratory of Neurogenetics and Channelopathies of Guangdong Province and Ministry of Education of China, Department of Neurology of the Second Affiliated Hospital of Guangzhou Medical University, Institute of Neuroscience, Guangzhou Medical University, Guangzhou 510260, China
| | - Jing-Yu Liu
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology and Center for Human Genome Research, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Zhi-Xian Yang
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| | - Zhong Chen
- Key Laboratory of Medical Neurobiology of the Ministry of Health of China, Department of Pharmacology, College of Pharmaceutical Sciences, School of Medicine, Zhejiang University, Hangzhou 310027, China.,Epilepsy Center, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310027, China
| | - Xiao Mao
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China
| | - Xin-Xiang Yan
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China
| | - Hong Jiang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China.,Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan 410008, China.,National Clinical Research Center for Geriatric Disorders, Central South University, Changsha, Hunan 410008, China.,Key Laboratory of Hunan Province in Neurodegenerative Disorders, Central South University, Changsha, Hunan 410008, China
| | - Lu Shen
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China.,Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan 410008, China.,National Clinical Research Center for Geriatric Disorders, Central South University, Changsha, Hunan 410008, China.,Key Laboratory of Hunan Province in Neurodegenerative Disorders, Central South University, Changsha, Hunan 410008, China
| | - Sheng-Di Chen
- Department of Neurology and Institute of Neurology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Li-Ming Zhang
- Department of Neurology, The First Affiliated Hospital of Harbin Medical University, Harbin 150001, China
| | - Bei-Sha Tang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China.,Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan 410008, China.,National Clinical Research Center for Geriatric Disorders, Central South University, Changsha, Hunan 410008, China.,Key Laboratory of Hunan Province in Neurodegenerative Disorders, Central South University, Changsha, Hunan 410008, China.,Collaborative Innovation Center for Brain Science, Shanghai 200032, China.,Collaborative Innovation Center for Genetics and Development, Shanghai 200433, China
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Verschuren EHJ, Hoenderop JGJ, Peters DJM, Arjona FJ, Bindels RJM. Tubular flow activates magnesium transport in the distal convoluted tubule. FASEB J 2018; 33:5034-5044. [DOI: 10.1096/fj.201802094r] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Eric H. J. Verschuren
- Department of PhysiologyRadboud Institute for Molecular Life SciencesRadboud University Medical Center Nijmegen The Netherlands
| | - Joost G. J. Hoenderop
- Department of PhysiologyRadboud Institute for Molecular Life SciencesRadboud University Medical Center Nijmegen The Netherlands
| | - Dorien J. M. Peters
- Department of Human GeneticsLeiden University Medical Centre Leiden The Netherlands
| | - Francisco J. Arjona
- Department of PhysiologyRadboud Institute for Molecular Life SciencesRadboud University Medical Center Nijmegen The Netherlands
| | - René J. M. Bindels
- Department of PhysiologyRadboud Institute for Molecular Life SciencesRadboud University Medical Center Nijmegen The Netherlands
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37
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Schäffers OJM, Hoenderop JGJ, Bindels RJM, de Baaij JHF. The rise and fall of novel renal magnesium transporters. Am J Physiol Renal Physiol 2018; 314:F1027-F1033. [DOI: 10.1152/ajprenal.00634.2017] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Body Mg2+ balance is finely regulated in the distal convoluted tubule (DCT), where a tight interplay among transcellular reabsorption, mitochondrial exchange, and basolateral extrusion takes place. In the last decades, several research groups have aimed to identify the molecular players in these processes. A multitude of proteins have been proposed to function as Mg2+ transporter in eukaryotes based on phylogenetic analysis, differential gene expression, and overexpression studies. However, functional evidence for many of these proteins is lacking. The aim of this review is, therefore, to critically reconsider all putative Mg2+ transporters and put their presumed function in context of the renal handling of Mg2+. Sufficient experimental evidence exists to acknowledge transient receptor potential melastatin (TRPM) 6 and TRPM7, solute carrier family 41 (SLC41) A1 and SLC41A3, and mitochondrial RNA splicing 2 (MRS2) as Mg2+ transporters. TRPM6/7 facilitate Mg2+ influx, SLC41A1 mediates Mg2+ extrusion, and MRS2 and SLC41A3 are implicated in mitochondrial Mg2+ homeostasis. These proteins are highly expressed in the DCT. The function of cyclin M (CNNM) proteins is still under debate. For the other proposed Mg2+ transporters including Mg2+ transporter subtype 1 (MagT1), nonimprinted in Prader-Willi/Angelman syndrome (NIPA), membrane Mg2+ transport (MMgT), Huntingtin-interacting protein 14 (HIP14), and ATP13A4, functional evidence is limited, or functions alternative to Mg2+ transport have been suggested. Additional characterization of their Mg2+ transport proficiency should be provided before further claims about their role as Mg2+ transporter can be made.
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Affiliation(s)
- Olivier J. M. Schäffers
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Joost G. J. Hoenderop
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - René J. M. Bindels
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jeroen H. F. de Baaij
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
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38
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van der Wijst J, Konrad M, Verkaart SAJ, Tkaczyk M, Latta F, Altmüller J, Thiele H, Beck B, Schlingmann KP, de Baaij JHF. A de novo KCNA1 Mutation in a Patient with Tetany and Hypomagnesemia. Nephron Clin Pract 2018; 139:359-366. [PMID: 29791908 DOI: 10.1159/000488954] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 03/31/2018] [Indexed: 11/19/2022] Open
Abstract
Mutations in the KCNA1 gene encoding the voltage-gated potassium (K+) channel Kv1.1 have been linked to rare neurological syndromes, episodic ataxia type 1 (EA1) and myokymia. In 2009, a KCNA1 mutation was identified in a large family with autosomal dominant hypomagnesemia. Despite efforts in establishing a genotype-phenotype correlation for the wide variety of symptoms in EA1, little is known on the serum magnesium (Mg2+) levels in these patients. In the present study, we describe a new de novo KCNA1 mutation in a Polish patient with tetany and hypomagnesemia. Electrophysiological and biochemical analyses were performed to determine the pathogenicity of the mutation. A female patient presented with low serum Mg2+ levels, renal Mg2+ wasting, muscle cramps, and tetanic episodes. Whole exome sequencing identified a p.Leu328Val mutation in KCNA1 encoding the Kv1.1 K+ channel. Electrophysiological examinations demonstrated that the p.Leu328Val mutation caused a dominant-negative loss of function of the encoded Kv1.1 channel. Cell surface biotinylation showed normal plasma membrane expression. Taken together, this is the second report linking KCNA1 with hypomagnesemia, thereby emphasizing the need for further evaluation of the clinical phenotypes observed in patients carrying KCNA1 mutations.
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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
| | - Martin Konrad
- Department of General Pediatrics, University Children's Hospital, Münster, Germany
| | - Sjoerd A J Verkaart
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Marcin Tkaczyk
- Department of Pediatrics, Immunology and Nephrology, Polish Mother's Memorial Hospital Research Institute, Lodz, Poland
| | - Femke Latta
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Janine Altmüller
- Cologne Center for Genomics, University of Cologne, Cologne, Germany
| | - Holger Thiele
- Cologne Center for Genomics, University of Cologne, Cologne, Germany
| | - Bodo Beck
- Department of Human Genetics, University of Cologne, Cologne, Germany
| | | | - Jeroen H F de Baaij
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
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39
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Curry JN, Yu AS. Magnesium Handling in the Kidney. Adv Chronic Kidney Dis 2018; 25:236-243. [PMID: 29793662 DOI: 10.1053/j.ackd.2018.01.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 12/26/2017] [Accepted: 01/02/2018] [Indexed: 02/07/2023]
Abstract
Magnesium is a divalent cation that fills essential roles as regulator and cofactor in a variety of biological pathways, and maintenance of magnesium balance is vital to human health. The kidney, in concert with the intestine, has an important role in maintaining magnesium homeostasis. Although micropuncture and microperfusion studies in the mammalian nephron have shone a light on magnesium handling in the various nephron segments, much of what we know about the protein mediators of magnesium handling in the kidney have come from more recent genetic studies. In the proximal tubule and thick ascending limb, magnesium reabsorption is believed to occur primarily through the paracellular shunt pathway, which ultimately depends on the electrochemical gradient setup by active sodium reabsorption. In the distal convoluted tubule, magnesium transport is transcellular, although magnesium reabsorption also appears to be related to active sodium reabsorption in this segment. In addition, evidence suggests that magnesium transport is highly regulated, although a specific hormonal regulator of extracellular magnesium has yet to be identified.
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Tian WT, Huang XJ, Mao X, Liu Q, Liu XL, Zeng S, Guo XN, Shen JY, Xu YQ, Tang HD, Yin XM, Zhang M, Tang WG, Liu XR, Tang BS, Chen SD, Cao L. Proline-rich transmembrane protein 2-negative paroxysmal kinesigenic dyskinesia: Clinical and genetic analyses of 163 patients. Mov Disord 2018; 33:459-467. [PMID: 29356177 DOI: 10.1002/mds.27274] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 11/06/2017] [Accepted: 11/26/2017] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Paroxysmal kinesigenic dyskinesia is the most common type of paroxysmal dyskinesia. Approximately half of the cases of paroxysmal kinesigenic dyskinesia worldwide are attributable to proline-rich transmembrane protein 2 mutations. OBJECTIVE The objective of this study was to investigate potential causative genes and clinical characteristics in proline-rich transmembrane protein 2-negative patients with paroxysmal kinesigenic dyskinesia. METHODS We analyzed clinical manifestations and performed exome sequencing in a cohort of 163 proline-rich transmembrane protein 2-negative probands, followed by filtering data with a paroxysmal movement disorders gene panel. Sanger sequencing, segregation analysis, and phenotypic reevaluation were used to substantiate the findings. RESULTS The clinical characteristics of the enrolled 163 probands were summarized. A total of 39 heterozygous variants were identified, of which 33 were classified as benign, likely benign, and uncertain significance. The remaining 6 variants (3 novel, 3 documented) were pathogenic and likely pathogenic. Of these, 3 were de novo (potassium calcium-activated channel subfamily M alpha 1, c.1534A>G; solute carrier family 2 member 1, c.418G>A; sodium voltage-gated channel alpha subunit 8, c.3640G>A) in 3 sporadic individuals, respectively. The other 3 (paroxysmal nonkinesiogenic dyskinesia protein, c.956dupA; potassium voltage-gated channel subfamily A member 1, c.765C>A; Dishevelled, Egl-10, and Pleckstrin domain containing 5, c.3311C>T) cosegregated in 3 families. All 6 cases presented with typical paroxysmal kinesigenic dyskinesia characteristics, except for the Dishevelled, Egl-10, and Pleckstrin domain containing 5 family, where the proband's mother had abnormal discharges in her temporal lobes in addition to paroxysmal kinesigenic dyskinesia episodes. CONCLUSIONS Our findings extend the genotypic spectrum of paroxysmal kinesigenic dyskinesia and establish the associations between paroxysmal kinesigenic dyskinesia and genes classically related to other paroxysmal movement disorders. De novo variants might be a cause of sporadic paroxysmal kinesigenic dyskinesia. © 2018 International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Wo-Tu Tian
- Department of Neurology and Institute of Neurology, Rui Jin Hospital & Rui Jin Hospital North, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xiao-Jun Huang
- Department of Neurology and Institute of Neurology, Rui Jin Hospital & Rui Jin Hospital North, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xiao Mao
- Department of Neurology, Xiangya Hospital, Central South University, State Key Laboratory of Medical Genetics, Changsha, Hunan Province, China
| | - Qing Liu
- Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Xiao-Li Liu
- Department of Neurology and Institute of Neurology, Rui Jin Hospital & Rui Jin Hospital North, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Sheng Zeng
- Department of Neurology, Xiangya Hospital, Central South University, State Key Laboratory of Medical Genetics, Changsha, Hunan Province, China
| | - Xia-Nan Guo
- Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Jun-Yi Shen
- Department of Neurology and Institute of Neurology, Rui Jin Hospital & Rui Jin Hospital North, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yang-Qi Xu
- Department of Neurology and Institute of Neurology, Rui Jin Hospital & Rui Jin Hospital North, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Hui-Dong Tang
- Department of Neurology and Institute of Neurology, Rui Jin Hospital & Rui Jin Hospital North, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xiao-Meng Yin
- Department of Neurology, Xiangya Hospital, Central South University, State Key Laboratory of Medical Genetics, Changsha, Hunan Province, China
| | - Mei Zhang
- Department of Neurology, Huainan First People's Hospital affiliated to Bengbu Medical College, Huainan, Anhui Province, China
| | - Wei-Guo Tang
- Department of Neurology, Zhoushan Hospital, Zhoushan, Zhejiang Province, China
| | - Xiao-Rong Liu
- Institute of Neuroscience of the Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong Province, China
| | - Bei-Sha Tang
- Department of Neurology, Xiangya Hospital, Central South University, State Key Laboratory of Medical Genetics, Changsha, Hunan Province, China
| | - Sheng-Di Chen
- Department of Neurology and Institute of Neurology, Rui Jin Hospital & Rui Jin Hospital North, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Li Cao
- Department of Neurology and Institute of Neurology, Rui Jin Hospital & Rui Jin Hospital North, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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Abstract
PURPOSE OF REVIEW Identification of the mechanisms of magnesium absorption and reabsorption has markedly enhanced our understanding of the causes of hypomagnesemia. RECENT FINDINGS New gastrointestinal and renal causes of hypomagnesemia have been recently documented. SUMMARY The recognition of new mechanisms and causes of magnesium absorption and reabsorption should enhance the ability to monitor patients at risk for hypomagnesemia and improve our ability to mitigate the serious symptoms associated with this disorder.
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Giménez-Mascarell P, Schirrmacher CE, Martínez-Cruz LA, Müller D. Novel Aspects of Renal Magnesium Homeostasis. Front Pediatr 2018; 6:77. [PMID: 29686978 PMCID: PMC5900390 DOI: 10.3389/fped.2018.00077] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 03/13/2018] [Indexed: 12/29/2022] Open
Abstract
Magnesium (Mg2+) is indispensable for several vital functions, such as neurotransmission, cardiac conductance, blood glucose, blood pressure regulation, and proper function of more than 300 enzymes. Thus, Mg2+ homeostasis is subject to tight regulation. Besides the fast and immediate regulation of plasma Mg2+, a major part of Mg2+ homeostasis is realized by a concerted action of epithelial molecular structures that tightly control intestinal uptake and renal absorption. This mechanism is provided by a combination of para- and transcellular pathways. Whereas the first pathway provides the organism with a maximal amount of vital substances by a minimal energy expenditure, the latter enables controlling and fine-tuning by means of local and regional regulatory systems and also, hormonal control. The paracellular pathway is driven by an electrochemical gradient and realized in principal by the tight junction (TJ), a supramolecular organization of membrane-bound proteins and their adaptor and scaffolding proteins. TJ determinants are claudins (CLDN), a family of membrane spanning proteins that generate a barrier or a pore between two adjacent epithelial cells. Many insights into molecular mechanisms of Mg2+ handling have been achieved by the identification of alterations and mutations in human genes which cause disorders of paracellular Mg2+ pathways (CLDN10, CLDN14, CLDN16, CLDN19). Also, in the distal convoluted tubule, a basolateral protein, CNNM2, causes if mutated, familial dominant and also recessive renal Mg2+ wasting, albeit its true function has not been clarified yet, but is assumed to play a key role in the transcellular pathway. Moreover, mutations in human genes that are involved in regulating these proteins directly or indirectly cause, if mutated human diseases, mostly in combination with comorbidities as diabetes, cystic renal disease, or metabolic abnormalities. Generation and characterization of animal models harboring the corresponding mutations have further contributed to the elucidation of physiology and pathophysiology of Mg2+ disorders. Finally, high-end crystallization techniques allow understanding of Mg2+ handling in more detail. As this field is rapidly growing, we describe here the principles of physiology and pathophysiology of epithelial transport of renal Mg2+ homeostasis with emphasis on recently identified mechanisms involved.
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Affiliation(s)
| | - Carlotta Else Schirrmacher
- Department of Pediatric Gastroenterology, Nephrology and Metabolism, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | | | - Dominik Müller
- Department of Pediatric Gastroenterology, Nephrology and Metabolism, Charité - Universitätsmedizin Berlin, Berlin, Germany
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43
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Fehmi J, Scherer SS, Willison HJ, Rinaldi S. Nodes, paranodes and neuropathies. J Neurol Neurosurg Psychiatry 2018; 89:61-71. [PMID: 28819062 DOI: 10.1136/jnnp-2016-315480] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 06/28/2017] [Accepted: 06/29/2017] [Indexed: 12/13/2022]
Abstract
This review summarises recent evidence supporting the involvement of the specialised nodal and perinodal domains (the paranode and juxtaparanode) of myelinated axons in the pathology of acquired, inflammatory, peripheral neuropathies.The identification of new target antigens in the inflammatory neuropathies heralds a revolution in diagnosis, and has already begun to inform increasingly targeted and individualised therapies. Rapid progress in our basic understanding of the highly specialised nodal regions of peripheral nerves serves to strengthen the links between their unique microstructural identities, functions and pathologies. In this context, the detection of autoantibodies directed against nodal and perinodal targets is likely to be of increasing clinical importance. Antiganglioside antibodies have long been used in clinical practice as diagnostic serum biomarkers, and associate with specific clinical variants but not to the common forms of either acute or chronic demyelinating autoimmune neuropathy. It is now apparent that antibodies directed against several region-specific cell adhesion molecules, including neurofascin, contactin and contactin-associated protein, can be linked to phenotypically distinct peripheral neuropathies. Importantly, the immunological characteristics of these antibodies facilitate the prediction of treatment responsiveness.
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Affiliation(s)
- Janev Fehmi
- Department of Neurology, Southmead Hospital, Bristol, UK
| | - Steven S Scherer
- Department of Neurology, The Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Hugh J Willison
- Department of Neuroimmunology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Simon Rinaldi
- Department of Clinical Neurosciences, West Wing, John Radcliffe Hospital, Oxford, UK
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Li H, Sun S, Chen J, Xu G, Wang H, Qian Q. Genetics of Magnesium Disorders. KIDNEY DISEASES 2017; 3:85-97. [PMID: 29344503 DOI: 10.1159/000477730] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 05/23/2017] [Indexed: 12/30/2022]
Abstract
Background Magnesium (Mg2+), the second most abundant cation in the cell, is woven into a multitude of cellular functions. Dysmagnesemia is associated with multiple diseases and, when severe, can be life-threatening. Summary This review discusses Mg2+ homeostasis and function with specific focus on renal Mg2+ handling. Intrarenal channels and transporters related to Mg2+ absorption are discussed. Unraveling the rare genetic diseases with manifestations of dysmagnesemia has greatly increased our understanding of the complex and intricate regulatory network in the kidney, specifically, functions of tight junction proteins including claudin-14, -16, -19, and -10; apical ion channels including: TRPM6, Kv1.1, and ROMK; small regulatory proteins including AC3 and ANK3; and basolateral proteins including EGF receptor, γ-subunit (FXYD2) of Na-K-ATPase, Kir4.1, CaSR, CNNM2, and SLC41A. Although our understanding of Mg2+ handling of the kidney has expanded considerably in the last two decades, many questions remain. Future studies are needed to elucidate a multitude of unknown aspects of Mg2+ handling in the kidney. Key Message Understanding rare and genetic diseases of Mg2+ dysregulation has expanded our knowledge and furthers the development of strategies for preventing and managing dysmagnesemia.
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Affiliation(s)
- Heng Li
- Kidney Disease Center, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China.,Division of Nephrology and Hypertension, Department of Medicine, Mayo Clinic College of Medicine, Rochester, Minnesota, USA
| | - Shiren Sun
- Department of Nephrology, Xijing Hospital, The Fourth Military Medical University, Xian, China
| | - Jianghua Chen
- Kidney Disease Center, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
| | - Goushuang Xu
- Department of Nephrology, Xijing Hospital, The Fourth Military Medical University, Xian, China
| | - Hanmin Wang
- Department of Nephrology, Xijing Hospital, The Fourth Military Medical University, Xian, China
| | - Qi Qian
- Division of Nephrology and Hypertension, Department of Medicine, Mayo Clinic College of Medicine, Rochester, Minnesota, USA
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Viering DHHM, de Baaij JHF, Walsh SB, Kleta R, Bockenhauer D. Genetic causes of hypomagnesemia, a clinical overview. Pediatr Nephrol 2017; 32:1123-1135. [PMID: 27234911 PMCID: PMC5440500 DOI: 10.1007/s00467-016-3416-3] [Citation(s) in RCA: 91] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 05/02/2016] [Accepted: 05/04/2016] [Indexed: 12/16/2022]
Abstract
Magnesium is essential to the proper functioning of numerous cellular processes. Magnesium ion (Mg2+) deficits, as reflected in hypomagnesemia, can cause neuromuscular irritability, seizures and cardiac arrhythmias. With normal Mg2+ intake, homeostasis is maintained primarily through the regulated reabsorption of Mg2+ by the thick ascending limb of Henle's loop and distal convoluted tubule of the kidney. Inadequate reabsorption results in renal Mg2+ wasting, as evidenced by an inappropriately high fractional Mg2+ excretion. Familial renal Mg2+ wasting is suggestive of a genetic cause, and subsequent studies in these hypomagnesemic families have revealed over a dozen genes directly or indirectly involved in Mg2+ transport. Those can be classified into four groups: hypercalciuric hypomagnesemias (encompassing mutations in CLDN16, CLDN19, CASR, CLCNKB), Gitelman-like hypomagnesemias (CLCNKB, SLC12A3, BSND, KCNJ10, FYXD2, HNF1B, PCBD1), mitochondrial hypomagnesemias (SARS2, MT-TI, Kearns-Sayre syndrome) and other hypomagnesemias (TRPM6, CNMM2, EGF, EGFR, KCNA1, FAM111A). Although identification of these genes has not yet changed treatment, which remains Mg2+ supplementation, it has contributed enormously to our understanding of Mg2+ transport and renal function. In this review, we discuss general mechanisms and symptoms of genetic causes of hypomagnesemia as well as the specific molecular mechanisms and clinical phenotypes associated with each syndrome.
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Affiliation(s)
- Daan H H M Viering
- Centre for Nephrology, University College London, London, UK
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jeroen H F de Baaij
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Stephen B Walsh
- Centre for Nephrology, University College London, London, UK
| | - Robert Kleta
- Centre for Nephrology, University College London, London, UK.
- Paediatric Nephrology, Great Ormond Street Hospital, London, UK.
| | - Detlef Bockenhauer
- Centre for Nephrology, University College London, London, UK
- Paediatric Nephrology, Great Ormond Street Hospital, London, UK
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46
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Alexander RT, Dimke H. Effect of diuretics on renal tubular transport of calcium and magnesium. Am J Physiol Renal Physiol 2017; 312:F998-F1015. [DOI: 10.1152/ajprenal.00032.2017] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Revised: 02/22/2017] [Accepted: 02/27/2017] [Indexed: 01/07/2023] Open
Abstract
Calcium (Ca2+) and Magnesium (Mg2+) reabsorption along the renal tubule is dependent on distinct trans- and paracellular pathways. Our understanding of the molecular machinery involved is increasing. Ca2+ and Mg2+ reclamation in kidney is dependent on a diverse array of proteins, which are important for both forming divalent cation-permeable pores and channels, but also for generating the necessary driving forces for Ca2+ and Mg2+ transport. Alterations in these molecular constituents can have profound effects on tubular Ca2+ and Mg2+ handling. Diuretics are used to treat a large range of clinical conditions, but most commonly for the management of blood pressure and fluid balance. The pharmacological targets of diuretics generally directly facilitate sodium (Na+) transport, but also indirectly affect renal Ca2+ and Mg2+ handling, i.e., by establishing a prerequisite electrochemical gradient. It is therefore not surprising that substantial alterations in divalent cation handling can be observed following diuretic treatment. The effects of diuretics on renal Ca2+ and Mg2+ handling are reviewed in the context of the present understanding of basal molecular mechanisms of Ca2+ and Mg2+ transport. Acetazolamide, osmotic diuretics, Na+/H+ exchanger (NHE3) inhibitors, and antidiabetic Na+/glucose cotransporter type 2 (SGLT) blocking compounds, target the proximal tubule, where paracellular Ca2+ transport predominates. Loop diuretics and renal outer medullary K+ (ROMK) inhibitors block thick ascending limb transport, a segment with significant paracellular Ca2+ and Mg2+ transport. Thiazides target the distal convoluted tubule; however, their effect on divalent cation transport is not limited to that segment. Finally, potassium-sparing diuretics, which inhibit electrogenic Na+ transport at distal sites, can also affect divalent cation transport.
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Affiliation(s)
- R. Todd Alexander
- Membrane Protein Disease Research Group, Department of Physiology, University of Alberta, Edmonton, Canada
- Department of Pediatrics, University of Alberta, Edmonton, Canada; and
| | - Henrik Dimke
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
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Abstract
PURPOSE OF REVIEW Magnesium (Mg) imbalances are frequently overlooked. Hypermagnesemia usually occurs in preeclamptic women after Mg therapy or in end-stage renal disease patients, whereas hypomagnesemia is more common with a prevalence of up to 15% in the general population. Increasing evidence points toward a role for mild-to-moderate chronic hypomagnesemia in the pathogenesis of hypertension, type 2 diabetes mellitus, and metabolic syndrome. RECENT FINDINGS The kidneys are the major regulator of total body Mg homeostasis. Over the last decade, the identification of the responsible genes in rare genetic disorders has enhanced our understanding of how the kidney handles Mg. The different genetic disorders and medications contributing to abnormal Mg homeostasis are reviewed. SUMMARY As dysfunctional Mg homeostasis contributes to the development of many common human disorders, serum Mg deserves closer monitoring. Hypomagnesemic patients may be asymptomatic or may have mild symptoms. In severe hypomagnesemia, patients may present with neurological symptoms such as seizures, spasms, or cramps. Renal symptoms include nephrocalcinosis and impaired renal function. Most conditions affect tubular Mg reabsorption by disturbing the lumen-positive potential in the thick ascending limb or the negative membrane potential in the distal convoluted tubule.
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Horinouchi T, Nozu K, Kamiyoshi N, Kamei K, Togawa H, Shima Y, Urahama Y, Yamamura T, Minamikawa S, Nakanishi K, Fujimura J, Morioka I, Ninchoji T, Kaito H, Nakanishi K, Iijima K. Diagnostic strategy for inherited hypomagnesemia. Clin Exp Nephrol 2017; 21:1003-1010. [DOI: 10.1007/s10157-017-1396-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 02/16/2017] [Indexed: 12/01/2022]
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49
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Tristán-Clavijo E, Scholl FG, Macaya A, Iglesias G, Rojas AM, Lucas M, Castellano A, Martinez-Mir A. Dominant-negative mutation p.Arg324Thr in KCNA1 impairs Kv1.1 channel function in episodic ataxia. Mov Disord 2016; 31:1743-1748. [PMID: 27477325 DOI: 10.1002/mds.26737] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Revised: 06/09/2016] [Accepted: 06/26/2016] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND Episodic ataxia type 1 is a rare autosomal dominant neurological disorder caused by mutations in the KCNA1 gene that encodes the α subunit of voltage-gated potassium channel Kv1.1. The functional consequences of identified mutations on channel function do not fully correlate with the clinical phenotype of patients. METHODS A clinical and genetic study was performed in a family with 5 patients with episodic ataxia type 1, with concurrent epilepsy in 1 of them. Protein expression, modeling, and electrophysiological analyses were performed to study Kv1.1 function. RESULTS Whole-genome linkage and candidate gene analyses revealed the novel heterozygous mutation p.Arg324Thr in the KCNA1 gene. The encoded mutant Kv1.1 channel displays reduced currents and altered activation and inactivation. CONCLUSIONS Taken together, we provide genetic and functional evidence that mutation p.Arg324Thr in the KCNA1 gene is pathogenic and results in episodic ataxia type 1 through a dominant-negative effect. © 2016 International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Enriqueta Tristán-Clavijo
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain
| | - Francisco G Scholl
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain.,Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, Sevilla, Spain
| | - Alfons Macaya
- Grup de Recerca en Neurologia Infantil, Hospital Universitari Vall d'Hebron, Barcelona, Spain
| | - Gemma Iglesias
- Servicio de Pediatría, Neuropediatría, Hospital Universitario Puerta de Hierro, Majadahonda, Madrid, Spain
| | - Ana M Rojas
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain
| | - Miguel Lucas
- Servicio de Biología Molecular, Hospital Universitario Virgen Macarena, Facultad de Medicina, Sevilla, Spain
| | - Antonio Castellano
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain.,Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, Sevilla, Spain
| | - Amalia Martinez-Mir
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain
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50
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Abstract
Over the past decades, hypomagnesemia (serum Mg(2+) <0.7 mmol/L) has been strongly associated with type 2 diabetes mellitus (T2DM). Patients with hypomagnesemia show a more rapid disease progression and have an increased risk for diabetes complications. Clinical studies demonstrate that T2DM patients with hypomagnesemia have reduced pancreatic β-cell activity and are more insulin resistant. Moreover, dietary Mg(2+) supplementation for patients with T2DM improves glucose metabolism and insulin sensitivity. Intracellular Mg(2+) regulates glucokinase, KATP channels, and L-type Ca(2+) channels in pancreatic β-cells, preceding insulin secretion. Moreover, insulin receptor autophosphorylation is dependent on intracellular Mg(2+) concentrations, making Mg(2+) a direct factor in the development of insulin resistance. Conversely, insulin is an important regulator of Mg(2+) homeostasis. In the kidney, insulin activates the renal Mg(2+) channel transient receptor potential melastatin type 6 that determines the final urinary Mg(2+) excretion. Consequently, patients with T2DM and hypomagnesemia enter a vicious circle in which hypomagnesemia causes insulin resistance and insulin resistance reduces serum Mg(2+) concentrations. This Perspective provides a systematic overview of the molecular mechanisms underlying the effects of Mg(2+) on insulin secretion and insulin signaling. In addition to providing a review of current knowledge, we provide novel directions for future research and identify previously neglected contributors to hypomagnesemia in T2DM.
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Affiliation(s)
- Lisanne M M Gommers
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Nijmegen Medical Center, Nijmegen, the Netherlands
| | - Joost G J Hoenderop
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Nijmegen Medical Center, Nijmegen, the Netherlands
| | - René J M Bindels
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Nijmegen Medical Center, Nijmegen, the Netherlands
| | - Jeroen H F de Baaij
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Nijmegen Medical Center, Nijmegen, the Netherlands Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, U.K.
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