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Gonzalez-Vicente A, Saez F, Monzon CM, Asirwatham J, Garvin JL. Thick Ascending Limb Sodium Transport in the Pathogenesis of Hypertension. Physiol Rev 2019; 99:235-309. [PMID: 30354966 DOI: 10.1152/physrev.00055.2017] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The thick ascending limb plays a key role in maintaining water and electrolyte balance. The importance of this segment in regulating blood pressure is evidenced by the effect of loop diuretics or local genetic defects on this parameter. Hormones and factors produced by thick ascending limbs have both autocrine and paracrine effects, which can extend prohypertensive signaling to other structures of the nephron. In this review, we discuss the role of the thick ascending limb in the development of hypertension, not as a sole participant, but one that works within the rich biological context of the renal medulla. We first provide an overview of the basic physiology of the segment and the anatomical considerations necessary to understand its relationship with other renal structures. We explore the physiopathological changes in thick ascending limbs occurring in both genetic and induced animal models of hypertension. We then discuss the racial differences and genetic defects that affect blood pressure in humans through changes in thick ascending limb transport rates. Throughout the text, we scrutinize methodologies and discuss the limitations of research techniques that, when overlooked, can lead investigators to make erroneous conclusions. Thus, in addition to advancing an understanding of the basic mechanisms of physiology, the ultimate goal of this work is to understand our research tools, to make better use of them, and to contextualize research data. Future advances in renal hypertension research will require not only collection of new experimental data, but also integration of our current knowledge.
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Affiliation(s)
| | - Fara Saez
- Department of Physiology and Biophysics, Case Western Reserve University , Cleveland, Ohio
| | - Casandra M Monzon
- Department of Physiology and Biophysics, Case Western Reserve University , Cleveland, Ohio
| | - Jessica Asirwatham
- Department of Physiology and Biophysics, Case Western Reserve University , Cleveland, Ohio
| | - Jeffrey L Garvin
- Department of Physiology and Biophysics, Case Western Reserve University , Cleveland, Ohio
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102
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Disorders of renal NaCl transport and implications for blood pressure regulation. MED GENET-BERLIN 2019. [DOI: 10.1007/s11825-019-0232-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Abstract
Hypertension is one of the major risk factors for cardiovascular disease in industrialized societies. Substantial progress has been made in understanding its epidemiology, its pathophysiology, and its associated risks such as coronary artery disease, stroke, and heart failure. Because there is consensus that the abnormal retention of sodium by the kidney is a major important pathophysiological event in hypertension, this review focuses on mechanisms of renal NaCl transport and associated genetic disorders.
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103
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Abstract
PURPOSE OF REVIEW Antenatal Bartter's syndrome (aBS) is the most severe form of Bartter's syndrome, requiring close follow-up, in particular during the neonatal period, primarily because of prematurity. The recent identification of a novel and very severe form of aBS merits an update on this topic. RECENT FINDING Despite the identification of several genes involved in Bartter's syndrome, about 20% of patients clinically diagnosed with aBS remained without genetic explanation for decades. We recently identified mutations in MAGED2 as a cause of an X-linked form of aBS characterized by a very early onset of severe polyhydramnios and extreme prematurity leading to high mortality. Remarkably, all symptoms in surviving patients with MAGE-D2 mutations resolve spontaneously, within weeks after preterm birth. Interestingly, MAGE-D2 affects the expression of the sodium chloride cotransporters NKCC2 and NCC, explaining thereby the severity of the disease. Importantly, a more recent analysis of MAGED2 in a large French cohort of patients with aBS confirmed our data and showed that females can also be affected. SUMMARY MAGE-D2 is critical for renal salt reabsorption in the fetus, amniotic fluid volume regulation, and maintenance of pregnancy. Most importantly, MAGED2 must be included in the genetic screening of every form of aBS.
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104
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Acar F, Işik G, Mutlu M, Kader Ş, Aslan Y, Kalyoncu M. Antenatal bartter syndrome caused by a novel homozygous mutation in SLC12A1 Gene. Indian J Nephrol 2019; 29:360-363. [PMID: 31571745 PMCID: PMC6755923 DOI: 10.4103/ijn.ijn_175_18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Antenatal Bartter syndrome (BS) is an autosomal recessive hereditary renal tubular disorder caused by mutation in the solute carrier family 12 member 1 (SLC12A1) gene on chromosome 15q21.1. This syndrome is characterized by polyuria, hyponatremia, hypokalemic hypochloremic metabolic alkalosis, and hypercalciuria associated with increased urinary loss of electrolytes. Herein, we report a very low-birth-weight premature newborn with antenatal BS caused by a novel homozygous mutation in the SLC12A1 gene, c.596G>A (p.R199H).
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105
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Ares GR, Kassem KM, Ortiz PA. Fructose acutely stimulates NKCC2 activity in rat thick ascending limbs by increasing surface NKCC2 expression. Am J Physiol Renal Physiol 2018; 316:F550-F557. [PMID: 30516424 DOI: 10.1152/ajprenal.00136.2018] [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] [Indexed: 11/22/2022] Open
Abstract
The thick ascending limb (TAL) reabsorbs 25% of the filtered NaCl through the Na+-K+-2Cl- cotransporter (NKCC2). NKCC2 activity is directly related to surface NKCC2 expression and phosphorylation. Higher NaCl reabsorption by TALs is linked to salt-sensitive hypertension, which is linked to consumption of fructose in the diet. However, little is known about the effects of fructose on renal NaCl reabsorption. We hypothesized that fructose, but not glucose, acutely enhances TAL-dependent NaCl reabsorption by increasing NKCC2 activity via stimulation of surface NKCC2 levels and phosphorylation at Thr96/101. We found that fructose (5 mM) increased transport-related O2 consumption in TALs by 11.1 ± 3.2% ( P < 0.05). The effect of fructose on O2 consumption was blocked by furosemide. To study the effect of fructose on NKCC2 activity, we measured the initial rate of NKCC2-dependent thallium influx. We found that 20 min of treatment with fructose (5 mM) increased NKCC2 activity by 58.5 ± 16.9% ( P < 0.05). We then used surface biotinylation to measure surface NKCC2 levels in rat TALs. Fructose increased surface NKCC2 expression in a concentration-dependent manner (22 ± 5, 49 ± 10, and 101 ± 59% of baseline with 1, 5, and 10 mM fructose, respectively, P < 0.05), whereas glucose or a glucose metabolite did not. Fructose did not change NKCC2 phosphorylation at Thre96/101 or total NKCC2 expression. We concluded that acute fructose treatment increases NKCC2 activity by enhancing surface NKCC2 expression, rather than NKCC2 phosphorylation. Our data suggest that fructose consumption could contribute to salt-sensitive hypertension by stimulating NKCC2-dependent NaCl reabsorption in TALs.
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Affiliation(s)
- Gustavo R Ares
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital , Detroit, Michigan
| | - Kamal M Kassem
- Department of Internal Medicine, University of Cincinnati Medical Center , Cincinnati, Ohio
| | - Pablo A Ortiz
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital , Detroit, Michigan.,Department of Physiology, Wayne State University , Detroit, Michigan
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106
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Nephrolithiasis secondary to inherited defects in the thick ascending loop of henle and connecting tubules. Urolithiasis 2018; 47:43-56. [PMID: 30460527 DOI: 10.1007/s00240-018-1097-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 11/08/2018] [Indexed: 12/19/2022]
Abstract
Twin and genealogy studies suggest a strong genetic component of nephrolithiasis. Likewise, urinary traits associated with renal stone formation were found to be highly heritable, even after adjustment for demographic, anthropometric and dietary covariates. Recent high-throughput sequencing projects of phenotypically well-defined cohorts of stone formers and large genome-wide association studies led to the discovery of many new genes associated with kidney stones. The spectrum ranges from infrequent but highly penetrant variants (mutations) causing mendelian forms of nephrolithiasis (monogenic traits) to common but phenotypically mild variants associated with nephrolithiasis (polygenic traits). About two-thirds of the genes currently known to be associated with nephrolithiasis code for membrane proteins or enzymes involved in renal tubular transport. The thick ascending limb of Henle and connecting tubules are of paramount importance for renal water and electrolyte handling, urinary concentration and maintenance of acid-base homeostasis. In most instances, pathogenic variants in genes involved in thick ascending limb of Henle and connecting tubule function result in phenotypically severe disease, frequently accompanied by nephrocalcinosis with progressive CKD and to a variable degree by nephrolithiasis. The aim of this article is to review the current knowledge on kidney stone disease associated with inherited defects in the thick ascending loop of Henle and the connecting tubules. We also highlight recent advances in the field of kidney stone genetics that have implications beyond rare disease, offering new insights into the most common type of kidney stone disease, i.e., idiopathic calcium stone disease.
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107
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Abstract
Bartter syndrome is an inherited renal tubular disorder caused by a defective salt reabsorption in the thick ascending limb of loop of Henle, resulting in salt wasting, hypokalemia, and metabolic alkalosis. Mutations of several genes encoding the transporters and channels involved in salt reabsorption in the thick ascending limb cause different types of Bartter syndrome. A poor phenotype-genotype relationship due to the interaction with other cotransporters and different degrees of compensation through alternative pathways is currently reported. However, phenotypic identification still remains the first step to guide the suspicion of Bartter syndrome. Given the rarity of the syndrome, and the lack of genetic characterization in most cases, limited clinical evidence for treatment is available and the therapy is based mainly on the comprehension of renal physiology and relies on the physician's personal experiences. A better understanding of the mutated channels and transporters could possibly generate targets for specific treatment in the future, also encompassing drugs aiming to correct deficiencies in folding or plasma membrane expression of the mutated proteins.
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Affiliation(s)
- Tamara da Silva Cunha
- Nephrology Division, Universidade Federal de São Paulo (UNIFESP), Escola Paulista de Medicina, São Paulo, Brazil,
| | - Ita Pfeferman Heilberg
- Nephrology Division, Universidade Federal de São Paulo (UNIFESP), Escola Paulista de Medicina, São Paulo, Brazil,
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108
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Graham LA, Aman A, Campbell DD, Augley J, Graham D, McBride MW, Fraser NJ, Ferreri NR, Dominiczak AF, Padmanabhan S. Salt stress in the renal tubules is linked to TAL-specific expression of uromodulin and an upregulation of heat shock genes. Physiol Genomics 2018; 50:964-972. [PMID: 30216136 PMCID: PMC6293113 DOI: 10.1152/physiolgenomics.00057.2018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 08/20/2018] [Accepted: 09/12/2018] [Indexed: 12/15/2022] Open
Abstract
Previously, our comprehensive cardiovascular characterization study validated Uromodulin as a blood pressure gene. Uromodulin is a glycoprotein exclusively synthesized at the thick ascending limb of the loop of Henle and is encoded by the Umod gene. Umod-/- mice have significantly lower blood pressure than Umod+/+ mice, are resistant to salt-induced changes in blood pressure, and show a leftward shift in pressure-natriuresis curves reflecting changes of sodium reabsorption. Salt stress triggers transcription factors and genes that alter renal sodium reabsorption. To date there are no studies on renal transcriptome responses to salt stress. Here we aimed use RNA-Seq to delineate salt stress pathways in tubules isolated from Umod+/+ mice (a model of sodium retention) and Umod-/- mice (a model of sodium depletion) ± 300 mosmol sodium chloride ( n = 3 per group). In response to salt stress, the tubules of Umod+/+ mice displayed an upregulation of heat shock transcripts. The greatest changes occurred in the expression of: Hspa1a (Log2 fold change 4.35, P = 2.48 e-12) and Hspa1b (Log2 fold change 4.05, P = 2.48 e-12). This response was absent in tubules of Umod-/- mice. Interestingly, seven of the genes discordantly expressed in the Umod-/- tubules were electrolyte transporters. Our results are the first to show that salt stress in renal tubules alters the transcriptome, increasing the expression of heat shock genes. This direction of effect in Umod+/+ tubules suggest the difference is due to the presence of Umod facilitating greater sodium entry into the tubule cell reflecting a specific response to salt stress.
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Affiliation(s)
- Lesley A Graham
- The British Heart Foundation Centre of Excellence, Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary, and Life Sciences, University of Glasgow , Glasgow , United Kingdom
| | - Alisha Aman
- The British Heart Foundation Centre of Excellence, Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary, and Life Sciences, University of Glasgow , Glasgow , United Kingdom
| | - Desmond D Campbell
- The British Heart Foundation Centre of Excellence, Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary, and Life Sciences, University of Glasgow , Glasgow , United Kingdom
| | - Julian Augley
- Wolfson Wohl Cancer Research Centre, Glasgow Polyomics, University of Glasgow, Bearsden, United Kingdom
| | - Delyth Graham
- The British Heart Foundation Centre of Excellence, Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary, and Life Sciences, University of Glasgow , Glasgow , United Kingdom
| | - Martin W McBride
- The British Heart Foundation Centre of Excellence, Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary, and Life Sciences, University of Glasgow , Glasgow , United Kingdom
| | - Niall J Fraser
- University of Dundee, Ninewells Hospital , Dundee , United Kingdom
| | - Nicholas R Ferreri
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Anna F Dominiczak
- The British Heart Foundation Centre of Excellence, Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary, and Life Sciences, University of Glasgow , Glasgow , United Kingdom
| | - Sandosh Padmanabhan
- The British Heart Foundation Centre of Excellence, Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary, and Life Sciences, University of Glasgow , Glasgow , United Kingdom
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109
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Wang C, Chen Y, Zheng B, Zhu M, Fan J, Wang J, Jia Z, Huang S, Zhang A. Novel compound heterozygous CLCNKB gene mutations (c.1755A>G/c.848_850delTCT) cause classic Bartter syndrome. Am J Physiol Renal Physiol 2018; 315:F844-F851. [PMID: 29442545 DOI: 10.1152/ajprenal.00077.2017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Inactivated variants in CLCNKB gene encoding the basolateral chloride channel ClC-Kb cause classic Bartter syndrome characterized by hypokalemic metabolic alkalosis and hyperreninemic hyperaldosteronism. Here, we identified two cBS siblings presenting hypokalemia in a Chinese family due to novel compound heterozygous CLCNKB mutations (c.848_850delTCT/c.1755A>G). Compound heterozygosity was confirmed by amplifying and sequencing the patient's genomic DNA. The synonymous mutation c.1755A>G (Thr585Thr) was located at +2 bp from the 5' splice donor site in exon 15. Further transcript analysis demonstrated that this single nucleotide mutation causes exclusion of exon 15 in the cDNA from the proband and his mother. Furthermore, we investigated the expression and protein trafficking change of c.848_850delTCT (ΔTCT) and exon 15 deletion (ΔE15) mutation in vitro. The ΔE15 mutation markedly decreased the expression of ClC-Kb and resulted in a low-molecular-weight band (~55 kDa) trapping in the endoplasmic reticulum, while the ΔTCT mutant only decreased the total and plasma membrane ClC-Kb protein expression but did not affect the subcellular localization. Finally, we studied the physiological functions of mutations by using whole cell patch-clamp and found that the ΔE15 or ΔTCT mutation decreased the current of the ClC-Kb/barttin channel. These results suggested that the compound defective mutations of the CLCNKB gene are the molecular mechanism of the two cBS siblings.
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Affiliation(s)
- Chunli Wang
- Nanjing Key Laboratory of Pediatrics, Children's Hospital of Nanjing Medical University , Nanjing , China
| | - Ying Chen
- Department of Nephrology, Children's Hospital of Nanjing Medical University , Nanjing , China
| | - Bixia Zheng
- Nanjing Key Laboratory of Pediatrics, Children's Hospital of Nanjing Medical University , Nanjing , China
| | - Mengshu Zhu
- Nanjing Key Laboratory of Pediatrics, Children's Hospital of Nanjing Medical University , Nanjing , China
| | - Jia Fan
- Department of Physiology, Nanjing Medical University , Nanjing , China
| | - Juejin Wang
- Department of Physiology, Nanjing Medical University , Nanjing , China
| | - Zhanjun Jia
- Nanjing Key Laboratory of Pediatrics, Children's Hospital of Nanjing Medical University , Nanjing , China
| | - Songming Huang
- Department of Nephrology, Children's Hospital of Nanjing Medical University , Nanjing , China.,Jiangsu Key Laboratory of Pediatrics, Nanjing Medical University , Nanjing , China
| | - Aihua Zhang
- Department of Nephrology, Children's Hospital of Nanjing Medical University , Nanjing , China.,Jiangsu Key Laboratory of Pediatrics, Nanjing Medical University , Nanjing , China
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110
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Dalugama C, Pathirage M, Kularatne SAM. Bartter syndrome-like phenotype in a patient with diabetes: a case report. J Med Case Rep 2018; 12:222. [PMID: 30115098 PMCID: PMC6097298 DOI: 10.1186/s13256-018-1752-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Accepted: 06/22/2018] [Indexed: 01/06/2023] Open
Abstract
Background Bartter’s syndrome is a rare genetic tubulopathy affecting the loop of Henle leading to salt wasting. It is commonly seen in utero or in early neonatal period. Rare cases of acquired Bartter’s syndrome are reported in association with infections like tuberculosis, granulomatous conditions like sarcoidosis, autoimmune diseases, and drugs. The mainstay of management includes potassium, calcium, and magnesium supplementation. Case presentation We report the case of a 62-year-old Sri Lankan Sinhalese man with diabetes and hypertension presenting with generalized weakness with clinical evidence of proximal myopathy. He was severely hypokalemic with high urinary potassium excretion and hypochloremic metabolic alkalosis. He poorly responded to intravenously administered potassium supplements. A diagnosis of idiopathic Bartter-like phenotype was made. He responded well to spironolactone and indomethacin. Conclusions Patients presenting with body weakness need serum potassium estimation. Acquired Bartter’s syndrome although rare, should be ruled out in those with hypokalemia and metabolic alkalosis with increased urinary potassium loss with poor response to potassium replacement.
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Affiliation(s)
- Chamara Dalugama
- Department of Medicine, University of Peradeniya, Peradeniya, Sri Lanka.
| | - Manoji Pathirage
- Department of Medicine, University of Peradeniya, Peradeniya, Sri Lanka
| | - S A M Kularatne
- Department of Medicine, University of Peradeniya, Peradeniya, Sri Lanka
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111
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Fukunaga K, Matsumoto H, Wate M, Misawa K, Saito M, Matsuda H, Orito K. Effects of three infusion fluids with different sodium chloride contents on steady-state serum concentrations of bromide in dogs. J Vet Pharmacol Ther 2018; 41:684-690. [PMID: 30020534 DOI: 10.1111/jvp.12680] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 05/08/2018] [Indexed: 12/18/2022]
Abstract
Potassium bromide overdose (bromism) in the management of canine epilepsy has been known. However, a protocol to reduce bromide concentrations rapidly has not been previously established. The effects of three infusion fluids with different chloride contents on the steady-state serum concentrations of bromide in beagles were determined. After stabilization of the serum bromide concentrations, seven dogs were infused with saline (Na+ 154 mmol/L; Cl- 154 mmol/L), lactated Ringer's (Na+ 131 mmol/L; Cl- 110 mmol/L), or maintenance solutions (Na+ 35 mmol/L; Cl- 35 mmol/L) at a rate of 2 or 10 ml kg-1 hr-1 for 5 hr. Serum and urine were collected hourly, and the bromide concentrations were measured. When saline and lactated Ringer's solutions were infused at a rate of 10 ml kg-1 hr-1 for 5 hr, serum bromide concentrations were decreased by 14.24% and urine bromide concentrations by 17.63%, respectively. Of all compositions of infusion fluids, only sodium and chloride contents were associated with the decreased serum concentrations and the increased renal clearance of bromide. In summary, saline and lactated Ringer's solutions reduced serum bromide concentrations in a sodium chloride-dependent manner in dogs were found when infused at 10 ml kg-1 hr-1 for 5 hr.
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Affiliation(s)
- Koya Fukunaga
- Laboratory for Pharmacogenomics, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan.,Department of Physiology II, School of Veterinary Medicine, Azabu University, Sagamihara, Japan
| | - Hikaru Matsumoto
- Department of Physiology II, School of Veterinary Medicine, Azabu University, Sagamihara, Japan
| | - Michiko Wate
- Laboratory of Veterinary Surgery II, School of Veterinary Medicine, Azabu University, Sagamihara, Japan
| | - Karin Misawa
- Laboratory of Veterinary Surgery II, School of Veterinary Medicine, Azabu University, Sagamihara, Japan
| | - Miyoko Saito
- Laboratory of Veterinary Surgery II, School of Veterinary Medicine, Azabu University, Sagamihara, Japan
| | - Hiroshi Matsuda
- Laboratory of Veterinary Molecular Pathology and Therapeutics, Institute of Agriculture, Tokyo University of Agriculture and Technology, Tokyo, Japan
| | - Kensuke Orito
- Department of Physiology II, School of Veterinary Medicine, Azabu University, Sagamihara, Japan
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112
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Jentsch TJ, Pusch M. CLC Chloride Channels and Transporters: Structure, Function, Physiology, and Disease. Physiol Rev 2018; 98:1493-1590. [DOI: 10.1152/physrev.00047.2017] [Citation(s) in RCA: 214] [Impact Index Per Article: 35.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
CLC anion transporters are found in all phyla and form a gene family of eight members in mammals. Two CLC proteins, each of which completely contains an ion translocation parthway, assemble to homo- or heteromeric dimers that sometimes require accessory β-subunits for function. CLC proteins come in two flavors: anion channels and anion/proton exchangers. Structures of these two CLC protein classes are surprisingly similar. Extensive structure-function analysis identified residues involved in ion permeation, anion-proton coupling and gating and led to attractive biophysical models. In mammals, ClC-1, -2, -Ka/-Kb are plasma membrane Cl−channels, whereas ClC-3 through ClC-7 are 2Cl−/H+-exchangers in endolysosomal membranes. Biological roles of CLCs were mostly studied in mammals, but also in plants and model organisms like yeast and Caenorhabditis elegans. CLC Cl−channels have roles in the control of electrical excitability, extra- and intracellular ion homeostasis, and transepithelial transport, whereas anion/proton exchangers influence vesicular ion composition and impinge on endocytosis and lysosomal function. The surprisingly diverse roles of CLCs are highlighted by human and mouse disorders elicited by mutations in their genes. These pathologies include neurodegeneration, leukodystrophy, mental retardation, deafness, blindness, myotonia, hyperaldosteronism, renal salt loss, proteinuria, kidney stones, male infertility, and osteopetrosis. In this review, emphasis is laid on biophysical structure-function analysis and on the cell biological and organismal roles of mammalian CLCs and their role in disease.
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Affiliation(s)
- Thomas J. Jentsch
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin (MDC), Berlin, Germany; and Istituto di Biofisica, Consiglio Nazionale delle Ricerche, Genova, Italy
| | - Michael Pusch
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin (MDC), Berlin, Germany; and Istituto di Biofisica, Consiglio Nazionale delle Ricerche, Genova, Italy
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113
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Congenital chloride diarrhea needs to be distinguished from Bartter and Gitelman syndrome. J Hum Genet 2018; 63:887-892. [DOI: 10.1038/s10038-018-0470-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 04/18/2018] [Accepted: 04/30/2018] [Indexed: 12/19/2022]
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114
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Bazúa-Valenti S, Rojas-Vega L, Castañeda-Bueno M, Barrera-Chimal J, Bautista R, Cervantes-Pérez LG, Vázquez N, Plata C, Murillo-de-Ozores AR, González-Mariscal L, Ellison DH, Riccardi D, Bobadilla NA, Gamba G. The Calcium-Sensing Receptor Increases Activity of the Renal NCC through the WNK4-SPAK Pathway. J Am Soc Nephrol 2018; 29:1838-1848. [PMID: 29848507 DOI: 10.1681/asn.2017111155] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Accepted: 04/10/2018] [Indexed: 01/07/2023] Open
Abstract
Background Hypercalciuria can result from activation of the basolateral calcium-sensing receptor (CaSR), which in the thick ascending limb of Henle's loop controls Ca2+ excretion and NaCl reabsorption in response to extracellular Ca2+ However, the function of CaSR in the regulation of NaCl reabsorption in the distal convoluted tubule (DCT) is unknown. We hypothesized that CaSR in this location is involved in activating the thiazide-sensitive NaCl cotransporter (NCC) to prevent NaCl loss.Methods We used a combination of in vitro and in vivo models to examine the effects of CaSR on NCC activity. Because the KLHL3-WNK4-SPAK pathway is involved in regulating NaCl reabsorption in the DCT, we assessed the involvement of this pathway as well.Results Thiazide-sensitive 22Na+ uptake assays in Xenopus laevis oocytes revealed that NCC activity increased in a WNK4-dependent manner upon activation of CaSR with Gd3+ In HEK293 cells, treatment with the calcimimetic R-568 stimulated SPAK phosphorylation only in the presence of WNK4. The WNK4 inhibitor WNK463 also prevented this effect. Furthermore, CaSR activation in HEK293 cells led to phosphorylation of KLHL3 and WNK4 and increased WNK4 abundance and activity. Finally, acute oral administration of R-568 in mice led to the phosphorylation of NCC.Conclusions Activation of CaSR can increase NCC activity via the WNK4-SPAK pathway. It is possible that activation of CaSR by Ca2+ in the apical membrane of the DCT increases NaCl reabsorption by NCC, with the consequent, well known decrease of Ca2+ reabsorption, further promoting hypercalciuria.
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Affiliation(s)
- Silvana Bazúa-Valenti
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico.,Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - Lorena Rojas-Vega
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - María Castañeda-Bueno
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - Jonatan Barrera-Chimal
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | | | | | - Norma Vázquez
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Consuelo Plata
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - Adrián R Murillo-de-Ozores
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico.,Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - Lorenza González-Mariscal
- Department of Physiology, Biophysics and Neuroscience, Center for Research and Advanced Studies (Cinvestav), Mexico City, Mexico
| | - David H Ellison
- Department of Medicine, Oregon Health and Science University, Portland, Oregon.,Renal Section, Veterans Administration Portland Health Care System, Portland, Oregon
| | - Daniela Riccardi
- School of Biosciences, Cardiff University, Cardiff, United Kingdom; and
| | - Norma A Bobadilla
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico.,Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - Gerardo Gamba
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico; .,Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico.,Tecnológico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Monterrey, Nuevo León, Mexico
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Abstract
Hereditary kidney disease comprises approximately 10% of adults and nearly all children who require renal replacement therapy. Technologic advances have improved our ability to perform genetic diagnosis and enhanced our understanding of renal and syndromic diseases. In this article, we review the genetics of renal diseases, including common monogenic diseases such as polycystic kidney disease, Alport syndrome, and Fabry disease, as well as complex disorders such as congenital anomalies of the kidney and urinary tract. We provide the nephrologist with a general strategy to approach hereditary disorders, which includes a discussion of commonly used genetic tests, a guide to genetic counseling, and reproductive options such as prenatal diagnosis or pre-implantation genetic diagnosis for at-risk couples. Finally, we review pregnancy outcomes in certain renal diseases.
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Affiliation(s)
- Lakshmi Mehta
- Division of Medical Genetics, Department of Genetics and Genomic Sciences/Pediatrics, Icahn School of Medicine at Mount Sinai, New York, NY.
| | - Belinda Jim
- Division of Nephrology, Department of Medicine, Albert Einstein College of Medicine, Jacobi Medical Center, Bronx, NY
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116
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Dimke H, Schnermann J. Axial and cellular heterogeneity in electrolyte transport pathways along the thick ascending limb. Acta Physiol (Oxf) 2018; 223:e13057. [PMID: 29476644 DOI: 10.1111/apha.13057] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Revised: 01/27/2018] [Accepted: 02/17/2018] [Indexed: 12/21/2022]
Abstract
The thick ascending limb (TAL) extends from the border of the inner medulla to the renal cortex, thus ascending through regions with wide differences in tissue solute and electrolyte concentrations. Structural and functional differences between TAL cells in the medulla (mTAL) and the cortex (cTAL) would therefore be useful to adapt TAL transport function to a changing external fluid composition. While mechanisms common to all TAL cells play a central role in the reclamation of about 25% of the NaCl filtered by the kidney, morphological features, Na+ / K+ -ATPase activity, NKCC2 splicing and phosphorylation do vary between segments and cells. The TAL contributes to K+ homeostasis and TAL cells with high or low basolateral K+ conductances have been identified which may be involved in K+ reabsorption and secretion respectively. Although transport rates for HCO3- do not differ between mTAL and cTAL, divergent axial and cellular expression of H+ transport proteins in TAL have been documented. The reabsorption of the divalent cations Ca2+ and Mg2+ is highest in cTAL and paralleled by differences in divalent cation permeability and the expression of select claudins. Morphologically, two cell types with different cell surface phenotypes have been described that still need to be linked to specific functional characteristics. The unique external environment and its change along the longitudinal axis require an axial functional heterogeneity for the TAL to optimally participate in conserving electrolyte homeostasis. Despite substantial progress in understanding TAL function, there are still considerable knowledge gaps that are just beginning to become bridged.
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Affiliation(s)
- H. Dimke
- Department of Cardiovascular and Renal Research; Institute of Molecular Medicine; University of Southern Denmark; Odense Denmark
| | - J. Schnermann
- National Institute of Diabetes and Digestive and Kidney Diseases; Bethesda MD USA
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117
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Rahmati N, Hoebeek FE, Peter S, De Zeeuw CI. Chloride Homeostasis in Neurons With Special Emphasis on the Olivocerebellar System: Differential Roles for Transporters and Channels. Front Cell Neurosci 2018; 12:101. [PMID: 29765304 PMCID: PMC5938380 DOI: 10.3389/fncel.2018.00101] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 03/28/2018] [Indexed: 12/14/2022] Open
Abstract
The intraneuronal ionic composition is an important determinant of brain functioning. There is growing evidence that aberrant homeostasis of the intracellular concentration of Cl- ([Cl-]i) evokes, in addition to that of Na+ and Ca2+, robust impairments of neuronal excitability and neurotransmission and thereby neurological conditions. More specifically, understanding the mechanisms underlying regulation of [Cl-]i is crucial for deciphering the variability in GABAergic and glycinergic signaling of neurons, in both health and disease. The homeostatic level of [Cl-]i is determined by various regulatory mechanisms, including those mediated by plasma membrane Cl- channels and transporters. This review focuses on the latest advances in identification, regulation and characterization of Cl- channels and transporters that modulate neuronal excitability and cell volume. By putting special emphasis on neurons of the olivocerebellar system, we establish that Cl- channels and transporters play an indispensable role in determining their [Cl-]i and thereby their function in sensorimotor coordination.
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Affiliation(s)
- Negah Rahmati
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, Netherlands
| | - Freek E. Hoebeek
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, Netherlands
- NIDOD Institute, Wilhelmina Children's Hospital, University Medical Center Utrecht and Brain Center Rudolf Magnus, Utrecht, Netherlands
| | - Saša Peter
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, Netherlands
| | - Chris I. De Zeeuw
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, Netherlands
- Netherlands Institute for Neuroscience, Royal Dutch Academy for Arts and Sciences, Amsterdam, Netherlands
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118
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Dias CM, Valkenier H, Davis AP. Anthracene Bisureas as Powerful and Accessible Anion Carriers. Chemistry 2018; 24:6262-6268. [PMID: 29493830 PMCID: PMC5947650 DOI: 10.1002/chem.201800508] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Indexed: 01/07/2023]
Abstract
Synthetic anion carriers (anionophores) have potential as biomedical research tools and as treatments for conditions arising from defective natural transport systems (notably cystic fibrosis). Highly active anionophores that are readily accessible and easily deliverable are especially valuable. Previous work has resulted in steroid and trans-decalin based anionophores with exceptional activity for chloride/nitrate exchange in vesicles, but poor accessibility and deliverability. This work shows that anthracene 1,8-bisureas can fulfil all three criteria. In particular, a bis-nitrophenyl derivative is prepared in two steps from commercial starting materials, yet shows comparable transport activity to the best currently known. Moreover, unlike earlier highly active systems, it does not need to be preincorporated in test vesicles but can be introduced subsequent to vesicle formation. This transporter also shows the ability to transfer between vesicles, and is therefore uniquely effective for anion transport at low transporter loadings. The results suggest that anthracene bisureas are promising candidates for application in biological research and medicine.
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Affiliation(s)
| | - Hennie Valkenier
- Université Libre de BruxellesAvenue F.D. Roosevelt 50, CP165/641050BrusselsBelgium
| | - Anthony P. Davis
- School of ChemistryUniversity of BristolCantock's CloseBristolBS8 1TSUK
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119
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Trafficking and regulation of the NKCC2 cotransporter in the thick ascending limb. Curr Opin Nephrol Hypertens 2018; 26:392-397. [PMID: 28614115 DOI: 10.1097/mnh.0000000000000351] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
PURPOSE OF REVIEW The kidney Na-K-2Cl cotransporter (NKCC2) is essential for urinary concentration and renal electrolyte handling. Loss of function mutations in the NKCC2 gene cause urinary salt and potassium wasting, whereas excessive NKCC2 function has been linked to high blood pressure. Loop diuretics, targeting the transporter, are instrumental for relieving edema or hypertension. This review focuses on intrinsic mechanisms regulating NKCC2 activity at the posttranslational level, namely its trafficking and phosphorylation. RECENT FINDINGS Protein networks mediating cellular turnover of NKCC2 have recently received major attention. Several key components of its apical trafficking were identified, including respective chaperones, SNARE protein family members and raft-associated proteins. NKCC2 internalization has been characterized qualitatively and quantitatively. Kinase and phosphatase pathways regulating NKCC2 activity have been clarified and links between NKCC2 phosphorylation and trafficking proposed. Constitutive and inducible NKCC2 trafficking and phosphorylation mechanisms have been specified with focus on endocrine control of thick ascending limb (TAL) function by vasopressin. SUMMARY Proper NKCC2 trafficking and phosphorylation are critical to the TAL function in the physiological context of urinary concentration and extracellular volume regulation. Clarification of the underlying mechanisms and respective protein networks may open new therapeutic perspectives for better management of renal electrolyte disorders and blood pressure control.
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Delpire E, Gagnon KB. Na + -K + -2Cl - Cotransporter (NKCC) Physiological Function in Nonpolarized Cells and Transporting Epithelia. Compr Physiol 2018; 8:871-901. [PMID: 29687903 DOI: 10.1002/cphy.c170018] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Two genes encode the Na+ -K+ -2Cl- cotransporters, NKCC1 and NKCC2, that mediate the tightly coupled movement of 1Na+ , 1K+ , and 2Cl- across the plasma membrane of cells. Na+ -K+ -2Cl- cotransport is driven by the chemical gradient of the three ionic species across the membrane, two of them maintained by the action of the Na+ /K+ pump. In many cells, NKCC1 accumulates Cl- above its electrochemical potential equilibrium, thereby facilitating Cl- channel-mediated membrane depolarization. In smooth muscle cells, this depolarization facilitates the opening of voltage-sensitive Ca2+ channels, leading to Ca2+ influx, and cell contraction. In immature neurons, the depolarization due to a GABA-mediated Cl- conductance produces an excitatory rather than inhibitory response. In many cell types that have lost water, NKCC is activated to help the cells recover their volume. This is specially the case if the cells have also lost Cl- . In combination with the Na+ /K+ pump, the NKCC's move ions across various specialized epithelia. NKCC1 is involved in Cl- -driven fluid secretion in many exocrine glands, such as sweat, lacrimal, salivary, stomach, pancreas, and intestine. NKCC1 is also involved in K+ -driven fluid secretion in inner ear, and possibly in Na+ -driven fluid secretion in choroid plexus. In the thick ascending limb of Henle, NKCC2 activity in combination with the Na+ /K+ pump participates in reabsorbing 30% of the glomerular-filtered Na+ . Overall, many critical physiological functions are maintained by the activity of the two Na+ -K+ -2Cl- cotransporters. In this overview article, we focus on the functional roles of the cotransporters in nonpolarized cells and in epithelia. © 2018 American Physiological Society. Compr Physiol 8:871-901, 2018.
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Affiliation(s)
- Eric Delpire
- Department of Anesthesiology, Vanderbilt University Medical School, Nashville, Tennessee, USA
| | - Kenneth B Gagnon
- Division of Nephrology and Hypertension, Department of Medicine, University of Louisville School of Medicine, Louisville, Keystone, USA
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121
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Legrand A, Treard C, Roncelin I, Dreux S, Bertholet-Thomas A, Broux F, Bruno D, Decramer S, Deschenes G, Djeddi D, Guigonis V, Jay N, Khalifeh T, Llanas B, Morin D, Morin G, Nobili F, Pietrement C, Ryckewaert A, Salomon R, Vrillon I, Blanchard A, Vargas-Poussou R. Prevalence of Novel MAGED2 Mutations in Antenatal Bartter Syndrome. Clin J Am Soc Nephrol 2018; 13:242-250. [PMID: 29146702 PMCID: PMC5967426 DOI: 10.2215/cjn.05670517] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 10/02/2017] [Indexed: 12/12/2022]
Abstract
BACKGROUND AND OBJECTIVES Mutations in the MAGED2 gene, located on the X chromosome, have been recently detected in males with a transient form of antenatal Bartter syndrome or with idiopathic polyhydramnios. The aim of this study is to analyze the proportion of the population with mutations in this gene in a French cohort of patients with antenatal Bartter syndrome. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS The French cohort of patients with antenatal Bartter syndrome encompasses 171 families. Mutations in genes responsible for types 1-4 have been detected in 75% of cases. In patients without identified genetic cause (n=42), transient antenatal Bartter syndrome was reported in 12 cases. We analyzed the MAGED2 gene in the entire cohort of negative cases by Sanger sequencing and retrospectively collected clinical data regarding pregnancy as well as the postnatal outcome for positive cases. RESULTS We detected mutations in MAGED2 in 17 patients, including the 12 with transient antenatal Bartter syndrome, from 16 families. Fifteen different mutations were detected (one whole deletion, three frameshift, three splicing, three nonsense, two inframe deletions, and three missense); 13 of these mutations had not been previously described. Interestingly, two patients are females; in one of these patients our data are consistent with selective inactivation of chromosome X explaining the severity. The phenotypic presentation in our patients was variable and less severe than that of the originally described cases. CONCLUSIONS MAGED2 mutations explained 9% of cases of antenatal Bartter syndrome in a French cohort, and accounted for 38% of patients without other characterized mutations and for 44% of male probands of negative cases. Our study confirmed previously published data and showed that females can be affected. As a result, this gene must be included in the screening of the most severe clinical form of Bartter syndrome.
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Affiliation(s)
- Anne Legrand
- Due to the number of contributing authors, the affiliations are provided in the Supplemental Material
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122
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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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123
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Halbritter J, Seidel A, Müller L, Schönauer R, Hoppe B. Update on Hereditary Kidney Stone Disease and Introduction of a New Clinical Patient Registry in Germany. Front Pediatr 2018; 6:47. [PMID: 29564324 PMCID: PMC5850730 DOI: 10.3389/fped.2018.00047] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 02/19/2018] [Indexed: 12/15/2022] Open
Abstract
Kidney stone disease is an increasingly prevalent condition with remarkable clinical heterogeneity, with regards to stone composition, age of manifestation, rate of recurrence, and impairment of kidney function. Calcium-based kidney stones account for the vast majority of cases, but their etiology is poorly understood, notably their genetic drivers. As recent studies indicate, hereditary conditions are most likely underestimated in prevalence, and new disease genes are constantly being identified. As a consequence, there is an urgent need of a more efficient documentation and collection of cases with underlying hereditary conditions, to better understand shared phenotypic presentation and common molecular mechanisms. By implementation of a centralized patient registry on hereditary kidney stone disease in Germany, we aim to help closing the vast knowledge gap on genetics of kidney stone disease. In this context, clinical registries are indispensable for several reasons: first, delineating better phenotype-genotype associations will allow more precise patient stratification in future clinical research studies. Second, identifying new disease genes and new mechanisms will further reduce the rate of unknown nephrolithiasis/nephrocalcinosis etiology; and third, deciphering new molecular targets will pave the way to develop drugs for recurrence prevention in severely affected families.
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Affiliation(s)
- Jan Halbritter
- Division of Nephrology, Department of Internal Medicine, University of Leipzig, Leipzig, Germany
| | - Anna Seidel
- Division of Nephrology, Department of Internal Medicine, University of Leipzig, Leipzig, Germany
| | - Luise Müller
- Division of Nephrology, Department of Internal Medicine, University of Leipzig, Leipzig, Germany
| | - Ria Schönauer
- Division of Nephrology, Department of Internal Medicine, University of Leipzig, Leipzig, Germany
| | - Bernd Hoppe
- Division of Pediatric Nephrology, University Children's Hospital, Bonn, Germany
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124
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Meyer M, Berrios M, Lo C. Transient Antenatal Bartter's Syndrome: A Case Report. Front Pediatr 2018; 6:51. [PMID: 29594084 PMCID: PMC5857533 DOI: 10.3389/fped.2018.00051] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 02/23/2018] [Indexed: 12/01/2022] Open
Abstract
Antenatal Bartter's syndrome is a rare inherited disorder characterized by fetal polyhydramnios and polyuria that is usually detected between 24 and 30 weeks of gestation. However, a rare, severe, but transient form of antenatal Bartter's syndrome due to an x-linked melanoma-associated antigen D2 (MAGED2) mutation has recently been described. This transient type results in the earlier onset of severe polyhydramnios and preterm birth, but spontaneously resolves postnatally. Here, we present a case of a 29-week gestation male born to a mother with severe polyhydramnios, who was subsequently found to have a novel mutation for MAGED2 not previously reported. This is the first and only case not to be treated with indomethacin, yet still resulted in spontaneous resolution of symptoms. Our case suggests the need for awareness of and testing for this new mutation in cases of severe antenatal polyhydramnios and discusses the perinatal treatment of this condition.
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Affiliation(s)
- Michelle Meyer
- UCSF Benioff Children's Hospital Oakland, Oakland, CA, United States
| | - Margarita Berrios
- UCSF Benioff Children's Hospital Oakland, Oakland, CA, United States
| | - Christina Lo
- UCSF Benioff Children's Hospital Oakland, Oakland, CA, United States
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125
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Broeckx BJG, Peelman L, Saunders JH, Deforce D, Clement L. Using variant databases for variant prioritization and to detect erroneous genotype-phenotype associations. BMC Bioinformatics 2017; 18:535. [PMID: 29191167 PMCID: PMC5710091 DOI: 10.1186/s12859-017-1951-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Accepted: 11/22/2017] [Indexed: 01/08/2023] Open
Abstract
Background In the search for novel causal mutations, public and/or private variant databases are nearly always used to facilitate the search as they result in a massive reduction of putative variants in one step. Practically, variant filtering is often done by either using all variants from the variant database (called the absence-approach, i.e. it is assumed that disease-causing variants do not reside in variant databases) or by using the subset of variants with an allelic frequency > 1% (called the 1%-approach). We investigate the validity of these two approaches in terms of false negatives (the true disease-causing variant does not pass all filters) and false positives (a harmless mutation passes all filters and is erroneously retained in the list of putative disease-causing variants) and compare it with an novel approach which we named the quantile-based approach. This approach applies variable instead of static frequency thresholds and the calculation of these thresholds is based on prior knowledge of disease prevalence, inheritance models, database size and database characteristics. Results Based on real-life data, we demonstrate that the quantile-based approach outperforms the absence-approach in terms of false negatives. At the same time, this quantile-based approach deals more appropriately with the variable allele frequencies of disease-causing alleles in variant databases relative to the 1%-approach and as such allows a better control of the number of false positives. We also introduce an alternative application for variant database usage and the quantile-based approach. If disease-causing variants in variant databases deviate substantially from theoretical expectancies calculated with the quantile-based approach, their association between genotype and phenotype had to be reconsidered in 12 out of 13 cases. Conclusions We developed a novel method and demonstrated that this so-called quantile-based approach is a highly suitable method for variant filtering. In addition, the quantile-based approach can also be used for variant flagging. For user friendliness, lookup tables and easy-to-use R calculators are provided. Electronic supplementary material The online version of this article (doi: 10.1186/s12859-017-1951-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Bart J G Broeckx
- Laboratory of Animal Genetics, Faculty of Veterinary Medicine, Ghent University, Heidestraat 19, B-9820, Merelbeke, Belgium.
| | - Luc Peelman
- Laboratory of Animal Genetics, Faculty of Veterinary Medicine, Ghent University, Heidestraat 19, B-9820, Merelbeke, Belgium
| | - Jimmy H Saunders
- Department of Medical Imaging and Orthopedics, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Dieter Deforce
- Laboratory of Pharmaceutical Biotechnology, Faculty of Pharmaceutical Sciences, Ghent University, Ghent, Belgium
| | - Lieven Clement
- Department of Applied Mathematics, Computer Science and Statistics, Faculty of Sciences, Ghent University, Ghent, Belgium
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126
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Koumangoye R, Delpire E. DNPEP is not the only peptidase that produces SPAK fragments in kidney. Physiol Rep 2017; 5:5/21/e13479. [PMID: 29122955 PMCID: PMC5688775 DOI: 10.14814/phy2.13479] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Revised: 09/05/2017] [Accepted: 09/22/2017] [Indexed: 11/24/2022] Open
Abstract
SPAK (STE20/SPS1‐related proline/alanine‐rich kinase) regulates Na+ and Cl− reabsorption in the distal convoluted tubule, and possibly in the thick ascending limb of Henle. This kinase phosphorylates and activates the apical Na‐Cl cotransporter in the DCT. Western blot analysis reveals that SPAK in kidney exists as a full‐length protein as well as shorter fragments that might affect NKCC2 function in the TAL. Recently, we showed that kidney lysates exerts proteolytic activity towards SPAK, resulting in the formation of multiple SPAK fragments with possible inhibitory effects on the kinase. The proteolytic activity is mediated by a Zn2+ metalloprotease inhibited by 1,10‐phenanthroline, DTT, and EDTA. Size exclusion chromatography demonstrated that the protease was a high‐molecular‐weight protein. Protein identification by mass‐spectrometry analysis after ion exchange and size exclusion chromatography identified multiple proteases as possible candidates and aspartyl aminopeptidase, DNPEP, shared all the properties of the kidney lysate activity. Furthermore, recombinant GST‐DNPEP produced similar proteolytic pattern. No mouse knockout model was, however, available to be used as negative control. In this study, we used a DNPEP‐mutant mouse generated by EUCOMM as well as a novel CRISPR/cas9 mouse knockout to assess the activity of their kidney lysates towards SPAK. Two mouse models had to be used because different anti‐DNPEP antibodies provided conflicting data on whether the EUCOMM mouse resulted in a true knockout. We show that in the absence of DNPEP, the kidney lysates retain their ability to cleave SPAK, indicating that DNPEP might have been misidentified as the protease behind the kidney lysate activity, or that the aspartyl aminopeptidase might not be the only protease cleaving SPAK in kidney.
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Affiliation(s)
- Rainelli Koumangoye
- Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Eric Delpire
- Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, Tennessee
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Walsh PR, Tse Y, Ashton E, Iancu D, Jenkins L, Bienias M, Kleta R, Van't Hoff W, Bockenhauer D. Clinical and diagnostic features of Bartter and Gitelman syndromes. Clin Kidney J 2017; 11:302-309. [PMID: 29942493 PMCID: PMC6007694 DOI: 10.1093/ckj/sfx118] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Accepted: 09/12/2017] [Indexed: 12/31/2022] Open
Abstract
Background Bartter and Gitelman syndromes are autosomal recessive disorders of renal tubular salt handling. Due to their rarity, limited long-term data are available to inform prognosis and management. Methods Long-term longitudinal data were analysed for 45 children with pathogenic variants in SLC12A1 (n = 8), KCNJ1 (n = 8), CLCNKB (n = 17), BSND (n = 2) and SLC12A3 (n = 10) seen at a single centre between 1984 and 2014. Median follow-up was 8.9 [interquartile range (IQR) 0.7–18.1] years. Results Polyhydramnios and prematurity were seen in children with SLC12A1 and KCNJ1 mutations. Patients with CLCNKB mutations had the lowest serum potassium and serum magnesium and the highest serum bicarbonate levels. Fractional excretion of chloride was >0.5% in all patients prior to supplementation. Nephrocalcinosis at presentation was present in the majority of patients with SLC12A1 and KCNJ1 mutations, while it was only present in one patient with CLCNKB and not in SLC12A3 or BSND mutations. Growth was impaired, but within the normal range (median height standard deviation score −1.2 at the last follow-up). Impaired estimated glomerular filtration rate (eGFR <90 mL/min/1.73 m2) at the last follow-up was seen predominantly with SLC12A1 [71 mL/min/1.73 m2 (IQR 46–74)] and KCNJ1 [62 mL/min/1.73 m2 (IQR 48–72)] mutations. Pathological albuminuria was detected in 31/45 children. Conclusions Patients with Bartter and Gitelman syndromes had a satisfactory prognosis during childhood. However, decreased eGFR and pathologic proteinuria was evident in a large number of these patients, highlighting the need to monitor glomerular as well as tubular function. Electrolyte abnormalities were most severe in CLCNKB mutations both at presentation and during follow-up. Fractional excretion of chloride prior to supplementation is a useful screening investigation in children with hypokalaemic alkalosis to establish renal salt wasting.
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Affiliation(s)
- Patrick R Walsh
- Department of Nephrology, Great North Children's Hospital NHS Foundation Trust, Newcastle upon Tyne, UK
| | - Yincent Tse
- Department of Nephrology, Great North Children's Hospital NHS Foundation Trust, Newcastle upon Tyne, UK
| | - Emma Ashton
- Department of Nephrology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Daniela Iancu
- Division of Medicine, UCL Centre for Nephrology, London, UK
| | - Lucy Jenkins
- Department of Nephrology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Marc Bienias
- Department of Paediatrics, Medical Faculty Carl Gustav Carus, Technical University Dresden, Dresden, Germany
| | - Robert Kleta
- Department of Nephrology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK.,Division of Medicine, UCL Centre for Nephrology, London, UK
| | - William Van't Hoff
- Department of Nephrology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Detlef Bockenhauer
- Department of Nephrology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK.,Division of Medicine, UCL Centre for Nephrology, London, UK
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128
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Symonds JD, Zuberi SM. Genetics update: Monogenetics, polygene disorders and the quest for modifying genes. Neuropharmacology 2017; 132:3-19. [PMID: 29037745 DOI: 10.1016/j.neuropharm.2017.10.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 10/09/2017] [Accepted: 10/11/2017] [Indexed: 12/19/2022]
Abstract
The genetic channelopathies are a broad collection of diseases. Many ion channel genes demonstrate wide phenotypic pleiotropy, but nonetheless concerted efforts have been made to characterise genotype-phenotype relationships. In this review we give an overview of the factors that influence genotype-phenotype relationships across this group of diseases as a whole, using specific individual channelopathies as examples. We suggest reasons for the limitations observed in these relationships. We discuss the role of ion channel variation in polygenic disease and highlight research that has contributed to unravelling the complex aetiological nature of these conditions. We focus specifically on the quest for modifying genes in inherited channelopathies, using the voltage-gated sodium channels as an example. Epilepsy related to genetic channelopathy is one area in which precision medicine is showing promise. We will discuss the successes and limitations of precision medicine in these conditions. This article is part of the Special Issue entitled 'Channelopathies.'
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Affiliation(s)
- Joseph D Symonds
- The Paediatric Neurosciences Research Group, Royal Hospital for Children, Queen Elizabeth University Hospitals, Glasgow, UK; School of Medicine, University of Glasgow, Glasgow, UK
| | - Sameer M Zuberi
- The Paediatric Neurosciences Research Group, Royal Hospital for Children, Queen Elizabeth University Hospitals, Glasgow, UK; School of Medicine, University of Glasgow, Glasgow, UK.
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129
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Padmanabhan S, Joe B. Towards Precision Medicine for Hypertension: A Review of Genomic, Epigenomic, and Microbiomic Effects on Blood Pressure in Experimental Rat Models and Humans. Physiol Rev 2017; 97:1469-1528. [PMID: 28931564 PMCID: PMC6347103 DOI: 10.1152/physrev.00035.2016] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 04/28/2017] [Accepted: 04/29/2017] [Indexed: 12/11/2022] Open
Abstract
Compelling evidence for the inherited nature of essential hypertension has led to extensive research in rats and humans. Rats have served as the primary model for research on the genetics of hypertension resulting in identification of genomic regions that are causally associated with hypertension. In more recent times, genome-wide studies in humans have also begun to improve our understanding of the inheritance of polygenic forms of hypertension. Based on the chronological progression of research into the genetics of hypertension as the "structural backbone," this review catalogs and discusses the rat and human genetic elements mapped and implicated in blood pressure regulation. Furthermore, the knowledge gained from these genetic studies that provide evidence to suggest that much of the genetic influence on hypertension residing within noncoding elements of our DNA and operating through pervasive epistasis or gene-gene interactions is highlighted. Lastly, perspectives on current thinking that the more complex "triad" of the genome, epigenome, and the microbiome operating to influence the inheritance of hypertension, is documented. Overall, the collective knowledge gained from rats and humans is disappointing in the sense that major hypertension-causing genes as targets for clinical management of essential hypertension may not be a clinical reality. On the other hand, the realization that the polygenic nature of hypertension prevents any single locus from being a relevant clinical target for all humans directs future studies on the genetics of hypertension towards an individualized genomic approach.
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Affiliation(s)
- Sandosh Padmanabhan
- Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom; and Center for Hypertension and Personalized Medicine; Department of Physiology and Pharmacology, University of Toledo College of Medicine and Life Sciences, Toledo, Ohio
| | - Bina Joe
- Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom; and Center for Hypertension and Personalized Medicine; Department of Physiology and Pharmacology, University of Toledo College of Medicine and Life Sciences, Toledo, Ohio
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130
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Zhang J, Karimy JK, Delpire E, Kahle KT. Pharmacological targeting of SPAK kinase in disorders of impaired epithelial transport. Expert Opin Ther Targets 2017; 21:795-804. [PMID: 28679296 PMCID: PMC6081737 DOI: 10.1080/14728222.2017.1351949] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The mammalian SPS1-related proline/alanine-rich serine-threonine kinase SPAK (STK39) modulates ion transport across and between epithelial cells in response to environmental stimuli such osmotic stress and inflammation. Research over the last decade has established a central role for SPAK in the regulation of ion and water transport in the distal nephron, colonic crypts, and pancreatic ducts, and has implicated deregulated SPAK signaling in NaCl-sensitive hypertension, ulcerative colitis and Crohn's disease, and cystic fibrosis. Areas covered: We review recent advances in our understanding of the role of SPAK kinase in the regulation of epithelial transport. We highlight how SPAK signaling - including its upstream Cl- sensitive activators, the WNK kinases, and its downstream ion transport targets, the cation- Cl- cotransporters contribute to human disease. We discuss prospects for the pharmacotherapeutic targeting of SPAK kinase in specific human disorders that feature impaired epithelial homeostasis. Expert opinion: The development of novel drugs that antagonize the SPAK-WNK interaction, inhibit SPAK kinase activity, or disrupt SPAK kinase activation by interfering with its binding to MO25α/β could be useful adjuncts in essential hypertension, inflammatory colitis, and cystic fibrosis.
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Affiliation(s)
- Jinwei Zhang
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Hatherly Laboratory, Exeter, EX4 4PS, UK
| | - Jason K. Karimy
- Department of Neurosurgery, Yale School of Medicine, New Haven, CT 06510, USA
| | - Eric Delpire
- Department of Anesthesiolgy, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Kristopher T. Kahle
- Departments of Neurosurgery, Pediatrics, and Cellular & Molecular Physiology; and Centers for Mendelian Genomics, Yale School of Medicine, New Haven, CT 06510, USA
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131
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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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132
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Bongers EMHF, Shelton LM, Milatz S, Verkaart S, Bech AP, Schoots J, Cornelissen EAM, Bleich M, Hoenderop JGJ, Wetzels JFM, Lugtenberg D, Nijenhuis T. A Novel Hypokalemic-Alkalotic Salt-Losing Tubulopathy in Patients with CLDN10 Mutations. J Am Soc Nephrol 2017; 28:3118-3128. [PMID: 28674042 DOI: 10.1681/asn.2016080881] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 05/11/2017] [Indexed: 11/03/2022] Open
Abstract
Mice lacking distal tubular expression of CLDN10, the gene encoding the tight junction protein Claudin-10, show enhanced paracellular magnesium and calcium permeability and reduced sodium permeability in the thick ascending limb (TAL), leading to a urine concentrating defect. However, the function of renal Claudin-10 in humans remains undetermined. We identified and characterized CLDN10 mutations in two patients with a hypokalemic-alkalotic salt-losing nephropathy. The first patient was diagnosed with Bartter syndrome (BS) >30 years ago. At re-evaluation, we observed hypocalciuria and hypercalcemia, suggesting Gitelman syndrome (GS). However, serum magnesium was in the upper normal to hypermagnesemic range, thiazide responsiveness was not blunted, and genetic analyses did not show mutations in genes associated with GS or BS. Whole-exome sequencing revealed compound heterozygous CLDN10 sequence variants [c.446C>G (p.Pro149Arg) and c.465-1G>A (p.Glu157_Tyr192del)]. The patient had reduced urinary concentrating ability, with a preserved aquaporin-2 response to desmopressin and an intact response to furosemide. These findings were not in line with any other known salt-losing nephropathy. Subsequently, we identified a second unrelated patient showing a similar phenotype, in whom we detected compound heterozygous CLDN10 sequence variants [c.446C>G (p.(Pro149Arg) and c.217G>A (p.Asp73Asn)]. Cell surface biotinylation and immunofluorescence experiments in cells expressing the encoded mutants showed that only one mutation caused significant differences in Claudin-10 membrane localization and tight junction strand formation, indicating that these alterations do not fully explain the phenotype. These data suggest that pathogenic CLDN10 mutations affect TAL paracellular ion transport and cause a novel tight junction disease characterized by a non-BS, non-GS autosomal recessive hypokalemic-alkalotic salt-losing phenotype.
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Affiliation(s)
| | | | - Susanne Milatz
- Institute of Physiology, Christian Albrechts University Kiel, Kiel, Germany
| | | | | | | | | | - Markus Bleich
- Institute of Physiology, Christian Albrechts University Kiel, Kiel, Germany
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133
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Padmanabhan S, Aman A, Dominiczak AF. Genomics of hypertension. Pharmacol Res 2017; 121:219-229. [DOI: 10.1016/j.phrs.2017.04.031] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Revised: 04/28/2017] [Accepted: 04/29/2017] [Indexed: 01/11/2023]
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134
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Raina R, Chaturvedi T, Polaconda S, Siri Mukunda A, Kumar Sethi S, Krishnappa V. A unique finding of normal aldosterone level in Bartter’s syndrome. J Nephropathol 2017. [DOI: 10.15171/jnp.2017.59] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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135
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Bachmann S, Mutig K. Regulation of renal Na-(K)-Cl cotransporters by vasopressin. Pflugers Arch 2017; 469:889-897. [DOI: 10.1007/s00424-017-2002-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Revised: 05/16/2017] [Accepted: 05/17/2017] [Indexed: 10/19/2022]
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136
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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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137
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Rectal Cancer in a Patient with Bartter Syndrome: A Case Report. Genes (Basel) 2017; 8:genes8050139. [PMID: 28498361 PMCID: PMC5448013 DOI: 10.3390/genes8050139] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Revised: 03/30/2017] [Accepted: 05/03/2017] [Indexed: 12/02/2022] Open
Abstract
A woman with rectal cancer was scheduled for surgery. However, she also had hypokalemia, hyperreninemia, and hyperaldosteronism in the absence of any known predisposing factors or endocrine tumors. She was given intravenous potassium, and her blood abnormalities stabilized after tumor resection. Genetic analysis revealed mutations in several genes associated with Bartter syndrome (BS) and Gitelman syndrome, including SLC12A1, CLCNKB, CASR, SLC26A3, and SLC12A3. Prostaglandin E2 (PGE2) plays an important role in BS and worsens electrolyte abnormalities. The PGE2 level is reportedly increased in colorectal cancer, and in the present case, immunohistochemical examination revealed an increased PGE2 level in the tumor. We concluded that the tumor-related PGE2 elevation had worsened the patient’s BS, which became more manageable after tumor resection.
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138
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Welch TR, Shaffer DR, Feldman DR. Cisplatin Therapy Does Not Worsen Renal Function in Severe Antenatal Bartter Syndrome. Case Rep Nephrol Dial 2017; 7:49-54. [PMID: 28612006 PMCID: PMC5465520 DOI: 10.1159/000475838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Accepted: 04/14/2017] [Indexed: 11/19/2022] Open
Abstract
A 30-year-old man with severe antenatal Bartter syndrome, diagnosed and treated in infancy, developed testicular carcinoma. Despite the known renal complications of cisplatin, this drug was used for his chemotherapy because of its superior antineoplastic effect. Nonsteroidal anti-inflammatory drug administration was continued during cisplatin therapy. Despite an increase in his oral potassium requirement, renal function was maintained following completion of chemotherapy. In spite of its significant associated nephrotoxicity, cisplatin can be used in patients with severe antenatal Bartter syndrome if required for therapy of malignancy.
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Affiliation(s)
- Thomas R. Welch
- aDivision of Nephrology, Upstate Medical University/Upstate Golisano Children's Hospital, Syracuse, New York, USA
- *Thomas R. Welch, MD, Department of Pediatrics, Upstate Medical University/Upstate Golisano Children's Hospital, 750 E. Adams Street, Syracuse, NY 13210 (USA), E-Mail
| | - David R. Shaffer
- bNew York Oncology and Hematology Albany Medical Center, Albany, New York, USA
| | - Darren R. Feldman
- cGenitourinary Oncology Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, New York, USA
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139
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Graham LA, Dominiczak AF, Ferreri NR. Role of renal transporters and novel regulatory interactions in the TAL that control blood pressure. Physiol Genomics 2017; 49:261-276. [PMID: 28389525 PMCID: PMC5451551 DOI: 10.1152/physiolgenomics.00017.2017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 03/27/2017] [Accepted: 04/05/2017] [Indexed: 12/31/2022] Open
Abstract
Hypertension (HTN), a major public health issue is currently the leading factor in the global burden of disease, where associated complications account for 9.4 million deaths worldwide every year. Excessive dietary salt intake is among the environmental factors that contribute to HTN, known as salt sensitivity. The heterogeneity of salt sensitivity and the multiple mechanisms that link high salt intake to increases in blood pressure are of upmost importance for therapeutic application. A continual increase in the kidney's reabsorption of sodium (Na+) relies on sequential actions at various segments along the nephron. When the distal segments of the nephron fail to regulate Na+, the effects on Na+ homeostasis are unfavorable. We propose that the specific nephron region where increased active uptake occurs as a result of variations in Na+ reabsorption is at the thick ascending limb of the loop of Henle (TAL). The purpose of this review is to urge the consideration of the TAL as contributing to the pathophysiology of salt-sensitive HTN. Further research in this area will enable development of a therapeutic application for targeted treatment.
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Affiliation(s)
- Lesley A Graham
- BHF Glasgow Cardiovascular Research Centre, University of Glasgow Cardiovascular and Medical Sciences, Glasgow, United Kingdom; and
| | - Anna F Dominiczak
- BHF Glasgow Cardiovascular Research Centre, University of Glasgow Cardiovascular and Medical Sciences, Glasgow, United Kingdom; and
| | - Nicholas R Ferreri
- Department of Pharmacology, New York Medical College, Valhalla, New York
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140
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Abstract
Studies involving adoptive families and twins have demonstrated the genetic basis of hypertension and shown that genetic factors account for about 40% of the variance in blood pressure among individuals. Arterial hypertension is genetically complex: multiple genes influence the blood pressure phenotype through allelic effects from single genes and gene-gene interactions. Moreover, environmental factors also modify the blood pressure phenotype. This complexity explains why the identification of the underlying genes has not been as successful in hypertension as in other diseases (such as type 1 and type 2 diabetes mellitus). The identification of the genetic determinants of hypertension has been most successful in endocrine forms of hypertension, which have well-defined phenotypes that permit a precise patient stratification into homogeneous cohorts. A promising area for the application of genetic testing to personalized medicine is the prediction of responses and adverse reactions to antihypertensive drugs. The identification of genetic markers of drug response will enable the design of randomized controlled trials in much smaller series of patients than is currently possible, decreasing the costs and times from drug design to clinical use and ultimately providing patients and doctors with a larger number of tools to combat hypertension, the most important risk factor for cardiovascular disease. This Review focuses on the rapidly developing field of genetic testing in patients with arterial hypertension.
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Affiliation(s)
- Gian Paolo Rossi
- Clinica dell'Ipertensione Arteriosa, Department of Medicine (DIMED), University of Padua, Via Giustiniani 2, 35126 Padua, Italy
| | - Giulio Ceolotto
- Clinica dell'Ipertensione Arteriosa, Department of Medicine (DIMED), University of Padua, Via Giustiniani 2, 35126 Padua, Italy
| | - Brasilina Caroccia
- Clinica dell'Ipertensione Arteriosa, Department of Medicine (DIMED), University of Padua, Via Giustiniani 2, 35126 Padua, Italy
| | - Livia Lenzini
- Clinica dell'Ipertensione Arteriosa, Department of Medicine (DIMED), University of Padua, Via Giustiniani 2, 35126 Padua, Italy
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141
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Seys E, Andrini O, Keck M, Mansour-Hendili L, Courand PY, Simian C, Deschenes G, Kwon T, Bertholet-Thomas A, Bobrie G, Borde JS, Bourdat-Michel G, Decramer S, Cailliez M, Krug P, Cozette P, Delbet JD, Dubourg L, Chaveau D, Fila M, Jourde-Chiche N, Knebelmann B, Lavocat MP, Lemoine S, Djeddi D, Llanas B, Louillet F, Merieau E, Mileva M, Mota-Vieira L, Mousson C, Nobili F, Novo R, Roussey-Kesler G, Vrillon I, Walsh SB, Teulon J, Blanchard A, Vargas-Poussou R. Clinical and Genetic Spectrum of Bartter Syndrome Type 3. J Am Soc Nephrol 2017; 28:2540-2552. [PMID: 28381550 DOI: 10.1681/asn.2016101057] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Accepted: 02/27/2017] [Indexed: 12/30/2022] Open
Abstract
Bartter syndrome type 3 is a clinically heterogeneous hereditary salt-losing tubulopathy caused by mutations of the chloride voltage-gated channel Kb gene (CLCNKB), which encodes the ClC-Kb chloride channel involved in NaCl reabsorption in the renal tubule. To study phenotype/genotype correlations, we performed genetic analyses by direct sequencing and multiplex ligation-dependent probe amplification and retrospectively analyzed medical charts for 115 patients with CLCNKB mutations. Functional analyses were performed in Xenopus laevis oocytes for eight missense and two nonsense mutations. We detected 60 mutations, including 27 previously unreported mutations. Among patients, 29.5% had a phenotype of ante/neonatal Bartter syndrome (polyhydramnios or diagnosis in the first month of life), 44.5% had classic Bartter syndrome (diagnosis during childhood, hypercalciuria, and/or polyuria), and 26.0% had Gitelman-like syndrome (fortuitous discovery of hypokalemia with hypomagnesemia and/or hypocalciuria in childhood or adulthood). Nine of the ten mutations expressed in vitro decreased or abolished chloride conductance. Severe (large deletions, frameshift, nonsense, and essential splicing) and missense mutations resulting in poor residual conductance were associated with younger age at diagnosis. Electrolyte supplements and indomethacin were used frequently to induce catch-up growth, with few adverse effects. After a median follow-up of 8 (range, 1-41) years in 77 patients, chronic renal failure was detected in 19 patients (25%): one required hemodialysis and four underwent renal transplant. In summary, we report a genotype/phenotype correlation for Bartter syndrome type 3: complete loss-of-function mutations associated with younger age at diagnosis, and CKD was observed in all phenotypes.
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Affiliation(s)
- Elsa Seys
- Pediatric Nephrology Unit, American Memorial Hospital, Reims University Hospital, Reims, France
| | - Olga Andrini
- Unité Mixte de Recherche en Santé 1138, Team 3, Université Pierre et Marie Curie, Paris, France.,Faculté de Médecine, Université Paris Descartes, Paris, France
| | - Mathilde Keck
- Unité Mixte de Recherche en Santé 1138, Team 3, Université Pierre et Marie Curie, Paris, France.,Institut National de la Santé et la Recherche Médicale, Unité Mixte de Recherche en Santé 872, Paris, France
| | | | - Pierre-Yves Courand
- Centre d'Investigation Clinique, Hôpital Européen Georges Pompidou, Assistance Publique-Hôpitaux de Paris, Paris, France.,Cardiology Department, Hôpital de la Croix-Rousse, Hospices Civils de Lyon, Lyon, France.,Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé; Centre National de la Recherche Scientifique Unité Mixte de Recherche 5220; Institut National de la Santé et la Recherche Médicale, Unité 1044; Institut National de Sciences Appliquées-Lyon; Université Claude Bernard Lyon 1, France
| | | | - Georges Deschenes
- Pediatric Nephrology Unit, Hôpital Robert Debré, Assistance Publique-Hôpitaux de Paris, Paris, France.,Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte, Paris, France
| | - Theresa Kwon
- Pediatric Nephrology Unit, Hôpital Robert Debré, Assistance Publique-Hôpitaux de Paris, Paris, France.,Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte, Paris, France
| | - Aurélia Bertholet-Thomas
- Néphrogones, Centre de Référence des Maladies Rénales Rares, Pediatric Nephrology, Rhumatology and Dermatology Unit, Hôpital Femme-Mère-Enfant and
| | - Guillaume Bobrie
- Nephrology Unit, Clinique du Vert Galant, Tremblay-en-France, France
| | | | | | | | - Mathilde Cailliez
- Pediatric Nephrology Unit, Hôpital de la Timone, Assistance Publique des Hôpitaux de Marseille, Marseille, France
| | - Pauline Krug
- Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte, Paris, France.,Pediatric Nephrology Unit and
| | - Paul Cozette
- Nephrology Unit, Centre Hospitalier du Pays d'Aix, Aix-en-Provence, France
| | - Jean Daniel Delbet
- Pediatric Nephrology Unit, Hôpital Trousseau, Assistance Publique des Hôpitaux de Paris, Paris, France
| | - Laurence Dubourg
- Exploration Fonctionnelle Rénale et Métabolique, Groupement Hospitalier est Hôpital Edouard Herriot, Hospices Civils de Lyon, Lyon, France
| | - Dominique Chaveau
- Departement of Nephrology, Centre de Référence des Maladies Rénales Rares du Sud-Ouest, Hôpital de Toulouse, Université Paul Sabatier, Toulouse, France
| | - Marc Fila
- Pediatric Nephrology Unit, Centre Hospitalier Universitaire de Montpellier, Montpellier, France
| | - Noémie Jourde-Chiche
- Faculté de Médecine, Centre de Référence des Maladies Rénales Rares du Sud-Ouest, Aix-MarseilleUniversité-Vascular Research Center of Marseille, Marseille, France.,Nephrology Unit, Hôpital de la Conception, Assistance Publique des Hopitaux de Marseille, Marseille,France
| | - Bertrand Knebelmann
- Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte, Paris, France.,Department of Nephrology, Hôpital Necker-Enfants-malades, Assistance Publique des Hôpitaux de Paris, Paris, France
| | - Marie-Pierre Lavocat
- Departement of Pediatrics, Hôpital Nord, Centre Hospitalier Universitaire de Saint Etienne, Saint Etienne, France
| | - Sandrine Lemoine
- Exploration Fonctionnelle Rénale et Métabolique, Groupement Hospitalier est Hôpital Edouard Herriot, Hospices Civils de Lyon, Lyon, France
| | - Djamal Djeddi
- Department of Pediatrics and Adolescent Medicine, Centre Hospitalier Universitaire d'Amiens, Amiens, France
| | - Brigitte Llanas
- Service de Néphrologie Pédiatrique, Groupement Hospitalier Pellegrin, Centre Hospitalier Universitaire de Bordeaux, Centre de Référence des Maladies Rénales Rares du Sud-Ouest, Bordeaux, France
| | - Ferielle Louillet
- Department of Pediatrics, Centre Hospitalier Universitaire Charles Nicolle, Rouen, France
| | - Elodie Merieau
- Nephrology Unit,Centre Hospitalier Universitaire Tours, Tours, France
| | - Maria Mileva
- Department of Pediatrics, Centre Hospitalier Pierre Oudot de Bourgoin-Jallieu, Bourgoin-Jallieu, France
| | - Luisa Mota-Vieira
- Molecular Genetics Unit, Hospital do Divino Espírito Santo de Ponta Delgada, Entidade Pública Empresarial Regional, Açores, Portugal
| | - Christiane Mousson
- Nephrology Unit, Centre Hospitalier Universitaire de Dijon, Dijon, France
| | - François Nobili
- Pediatric Nephrology Unit, Centre Hospitalier Universitaire de Besançon, Besançon, France
| | - Robert Novo
- Pediatric Nephrology Unit, Hôpital Jeanne de Flandre, Centre Hospitalier Universitaire de Lille, Lille, France
| | | | - Isabelle Vrillon
- Pediatric Nephrology Unit, Hôpitaux de Brabois, Centre Hospitalier Universitaire de Nancy, Vandoeuvre Les Nancy, France
| | - Stephen B Walsh
- Centre for Nephrology, University College London, London, UK; and
| | - Jacques Teulon
- Unité Mixte de Recherche en Santé 1138, Team 3, Université Pierre et Marie Curie, Paris, France.,Institut National de la Santé et la Recherche Médicale, Unité Mixte de Recherche en Santé 872, Paris, France
| | - Anne Blanchard
- Faculté de Médecine, Université Paris Descartes, Paris, France.,Cardiology Department, Hôpital de la Croix-Rousse, Hospices Civils de Lyon, Lyon, France.,Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte, Paris, France.,Institut National de la Santé et la Recherche Médicale, Unité Mixte de Recherche en Santé 970, Paris-Cardiovascular Research Center, Paris, France
| | - Rosa Vargas-Poussou
- Department of Genetics and.,Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte, Paris, France.,Institut National de la Santé et la Recherche Médicale, Unité Mixte de Recherche en Santé 970, Paris-Cardiovascular Research Center, Paris, France
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142
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Singh R, Kursan S, Almiahoub MY, Almutairi MM, Garzón-Muvdi T, Alvarez-Leefmans FJ, Di Fulvio M. Plasma Membrane Targeting of Endogenous NKCC2 in COS7 Cells Bypasses Functional Golgi Cisternae and Complex N-Glycosylation. Front Cell Dev Biol 2017; 4:150. [PMID: 28101499 PMCID: PMC5209364 DOI: 10.3389/fcell.2016.00150] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 12/14/2016] [Indexed: 12/04/2022] Open
Abstract
Na+K+2Cl− co-transporters (NKCCs) effect the electroneutral movement of Na+-K+ and 2Cl− ions across the plasma membrane of vertebrate cells. There are two known NKCC isoforms, NKCC1 (Slc12a2) and NKCC2 (Slc12a1). NKCC1 is a ubiquitously expressed transporter involved in cell volume regulation, Cl− homeostasis and epithelial salt secretion, whereas NKCC2 is abundantly expressed in kidney epithelial cells of the thick ascending loop of Henle, where it plays key roles in NaCl reabsorption and electrolyte homeostasis. Although NKCC1 and NKCC2 co-transport the same ions with identical stoichiometry, NKCC1 actively co-transports water whereas NKCC2 does not. There is growing evidence showing that NKCC2 is expressed outside the kidney, but its function in extra-renal tissues remains unknown. The present study shows molecular and functional evidence of endogenous NKCC2 expression in COS7 cells, a widely used mammalian cell model. Endogenous NKCC2 is primarily found in recycling endosomes, Golgi cisternae, Golgi-derived vesicles, and to a lesser extent in the endoplasmic reticulum. Unlike NKCC1, NKCC2 is minimally hybrid/complex N-glycosylated under basal conditions and yet it is trafficked to the plasma membrane region of hyper-osmotically challenged cells through mechanisms that require minimal complex N-glycosylation or functional Golgi cisternae. Control COS7 cells exposed to slightly hyperosmotic (~6.7%) solutions for 16 h were not shrunken, suggesting that either one or both NKCC1 and NKCC2 may participate in cell volume recovery. However, NKCC2 targeted to the plasma membrane region or transient over-expression of NKCC2 failed to rescue NKCC1 in COS7 cells where NKCC1 had been silenced. Further, COS7 cells in which NKCC1, but not NKCC2, was silenced exhibited reduced cell size compared to control cells. Altogether, these results suggest that NKCC2 does not participate in cell volume recovery and therefore, NKCC1 and NKCC2 are functionally different Na+K+2Cl− co-transporters.
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Affiliation(s)
- Richa Singh
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University Dayton, OH, USA
| | - Shams Kursan
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University Dayton, OH, USA
| | - Mohamed Y Almiahoub
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University Dayton, OH, USA
| | - Mohammed M Almutairi
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University Dayton, OH, USA
| | - Tomás Garzón-Muvdi
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University Dayton, OH, USA
| | - Francisco J Alvarez-Leefmans
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University Dayton, OH, USA
| | - Mauricio Di Fulvio
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University Dayton, OH, USA
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143
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Wang HH, Feng Y, Li HB, Wu H, Mei LY, Wang XW, Jiang L, He CF. Digenic mutations involving both the BSND and GJB2 genes detected in Bartter syndrome type IV. Int J Pediatr Otorhinolaryngol 2017; 92:17-20. [PMID: 28012523 DOI: 10.1016/j.ijporl.2016.10.028] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 10/23/2016] [Accepted: 10/24/2016] [Indexed: 11/30/2022]
Abstract
Bartter syndrome type IV, characterized by salt-losing nephropathies and sensorineural deafness, is caused by mutations of BSND or simultaneous mutations of both CLCNKA and CLCNKB. GJB2 is the primary causative gene for non-syndromic sensorineural deafness and associated with several syndromic sensorineural deafness. Owing to the rarity of Bartter syndrome, only a few mutations have been reported in the abovementioned causative genes. To investigate the underlying mutations in a Chinese patient with Bartter syndrome type IV, genetic analysis of BSND, CLCNKA, CLCNKB and GJB2 were performed by polymerase chain reaction and direct sequencing. Finally, double homozygous mutations c.22C > T (p.Arg8Trp) and c.127G > A (Val43Ile) were detected in exon 1 of BSND. Intriguingly, compound heterozygous mutations c.235delC (p.Leu79CysfsX3) and c.109G > A (p.Val37Ile) were also revealed in exon 2 of GJB2 in the same patient. No pathogenic mutations were found in CLCNKA and CLCNKB. Our results indicated that the homozygous mutation c.22C > T was the key genetic reason for the proband, and a digenic effect of BSND and GJB2 might contributed to sensorineural deafness. To our knowledge, it was the first report showing that the GJB2 gene mutations were detected in Bartter syndrome.
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Affiliation(s)
- Hong-Han Wang
- Department of Head and Neck Surgery, Hunan Cancer Hospital and the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, Hunan, 410013, China
| | - Yong Feng
- Department of Otolaryngology, Head & Neck Surgery, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China; State Key Laboratory of Medical Genetics, Changsha, 410078, Hunan, China; Province Key Laboratory of Otolaryngology Critical Diseases, Changsha, 410008, Hunan, China
| | - Hai-Bo Li
- Department of Ophtalmology, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China
| | - Hong Wu
- Department of Otolaryngology, Head & Neck Surgery, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China
| | - Ling-Yun Mei
- Department of Otolaryngology, Head & Neck Surgery, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China
| | - Xing-Wei Wang
- Department of Otolaryngology, Head & Neck Surgery, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China
| | - Lu Jiang
- Department of Otolaryngology, Head & Neck Surgery, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China
| | - Chu-Feng He
- Department of Otolaryngology, Head & Neck Surgery, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China.
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144
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Breinbjerg A, Siggaard Rittig C, Gregersen N, Rittig S, Hvarregaard Christensen J. A novel variant in the SLC12A1 gene in two families with antenatal Bartter syndrome. Acta Paediatr 2017; 106:161-167. [PMID: 27748541 DOI: 10.1111/apa.13635] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Revised: 09/20/2016] [Accepted: 10/13/2016] [Indexed: 12/27/2022]
Abstract
AIM Bartter syndrome is an autosomal-recessive inherited disease in which patients present with hypokalaemia and metabolic alkalosis. We present two apparently nonrelated cases with antenatal Bartter syndrome type I, due to a novel variant in the SLC12A1 gene encoding the bumetanide-sensitive sodium-(potassium)-chloride cotransporter 2 in the thick ascending limb of the loop of Henle. METHODS Blood samples were received from the two cases and 19 of their relatives, and deoxyribonucleic acid was extracted. The coding regions of the SLC12A1 gene were amplified using polymerase chain reaction, followed by bidirectional direct deoxyribonucleic acid sequencing. RESULTS Each affected child in the two families was homozygous for a novel inherited variant in the SLC12A1gene, c.1614T>A. The variant predicts a change from a tyrosine codon to a stop codon (p.Tyr538Ter). The two cases presented antenatally and at six months of age, respectively. CONCLUSION The two cases were homozygous for the same variant in the SLC12A1 gene, but presented clinically at different ages. This could eventually be explained by the presence of other gene variants or environmental factors modifying the phenotypes. The phenotypes of the patients were similar to other patients with antenatal Bartter syndrome.
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Affiliation(s)
- Anders Breinbjerg
- Department of Pediatrics; Aarhus University Hospital; Aarhus Denmark
| | | | - Niels Gregersen
- Research Unit for Molecular Medicine; Aarhus University Hospital; Aarhus Denmark
| | - Søren Rittig
- Department of Pediatrics; Aarhus University Hospital; Aarhus Denmark
| | - Jane Hvarregaard Christensen
- Department of Pediatrics; Aarhus University Hospital; Aarhus Denmark
- Department of Biomedicine; Aarhus University; Aarhus Denmark
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145
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Pao AC, Chang TI. An experimentum crucis in salt sensitivity. Am J Physiol Renal Physiol 2017; 312:F190-F191. [DOI: 10.1152/ajprenal.00510.2016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Accepted: 09/14/2016] [Indexed: 11/22/2022] Open
Affiliation(s)
- Alan C. Pao
- Department of Medicine, Stanford University School of Medicine, Stanford, California; and
- Veterans Affairs Palo Alto Health Care System, Palo Alto, California
| | - Tara I. Chang
- Department of Medicine, Stanford University School of Medicine, Stanford, California; and
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146
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Sun M, Ning J, Xu W, Zhang H, Zhao K, Li W, Li G, Li S. Genetic heterogeneity in patients with Bartter syndrome type 1. Mol Med Rep 2016; 15:581-590. [PMID: 28000888 PMCID: PMC5364841 DOI: 10.3892/mmr.2016.6063] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 11/01/2016] [Indexed: 12/28/2022] Open
Abstract
Bartter syndrome (BS) type 1 is an autosomal recessive kidney disorder caused by loss-of-function mutations in the solute carrier family 12 member 1 (SLC12A1) gene. To date, 72 BS type 1 patients harboring SLC12A1 mutations have been documented. Of these 144 alleles studied, 68 different disease-causing mutations have been detected in 129 alleles, and no mutation was detected in the remaining 15 alleles. The mutation types included missense/nonsense mutations, splicing mutations and small insertions and deletions ranging from 1 to 4 nucleotides. A large deletion encompassing a whole exon in the SLC12A1 gene has not yet been reported. The current study initially identified an undocumented homozygous frameshift mutation (c.1833delT) by Sanger sequencing analysis of a single infant with BS type 1. However, in a subsequent analysis, the mutation was detected only in the father's DNA. Upon further investigation using a next-generation sequencing approach, a deletion in exons 14 and 15 in both the patient and patient's mother was detected. The deletion was subsequently confirmed by use of a long-range polymerase chain reaction and was determined to be 3.16 kb in size based on sequencing of the junction fragment. The results of the present study demonstrated that pathogenic variants of SLC12A1 are heterogeneous. Large deletions appear to serve an etiological role in BS type 1, and may be more prevalent than previously thought.
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Affiliation(s)
- Mingran Sun
- Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma, OK 73117, USA
| | - Jing Ning
- Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma, OK 73117, USA
| | - Weihong Xu
- Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma, OK 73117, USA
| | - Han Zhang
- Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma, OK 73117, USA
| | - Kaishu Zhao
- Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma, OK 73117, USA
| | - Wenfu Li
- Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma, OK 73117, USA
| | - Guiying Li
- Key Laboratory for Molecular Enzymology and Engineering, The Ministry of Education, School of Life Sciences, Jilin University, Changchun, Jilin 130012, P.R. China
| | - Shibo Li
- Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma, OK 73117, USA
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147
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Oliveira B, Kleta R, Bockenhauer D, Walsh SB. Genetic, pathophysiological, and clinical aspects of nephrocalcinosis. Am J Physiol Renal Physiol 2016; 311:F1243-F1252. [DOI: 10.1152/ajprenal.00211.2016] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Accepted: 09/06/2016] [Indexed: 12/25/2022] Open
Abstract
Nephrocalcinosis describes the ectopic deposition of calcium salts in the kidney parenchyma. Nephrocalcinosis can result from a number of acquired causes but also an even greater number of genetic diseases, predominantly renal but also extrarenal. Here we provide a review of the genetic causes of nephrocalcinosis, along with putative mechanisms, illustrated by human and animal data.
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Affiliation(s)
- Ben Oliveira
- University College London, Centre for Nephrology, London, United Kingdom
| | - Robert Kleta
- University College London, Centre for Nephrology, London, United Kingdom
| | - Detlef Bockenhauer
- University College London, Centre for Nephrology, London, United Kingdom
| | - Stephen B. Walsh
- University College London, Centre for Nephrology, London, United Kingdom
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148
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Delpire E, Wolfe L, Flores B, Koumangoye R, Schornak CC, Omer S, Pusey B, Lau C, Markello T, Adams DR. A patient with multisystem dysfunction carries a truncation mutation in human SLC12A2, the gene encoding the Na-K-2Cl cotransporter, NKCC1. Cold Spring Harb Mol Case Stud 2016; 2:a001289. [PMID: 27900370 PMCID: PMC5111002 DOI: 10.1101/mcs.a001289] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 10/10/2016] [Indexed: 12/30/2022] Open
Abstract
This study describes a 13-yr-old girl with orthostatic intolerance, respiratory weakness, multiple endocrine abnormalities, pancreatic insufficiency, and multiorgan failure involving the gut and bladder. Exome sequencing revealed a de novo, loss-of-function allele in SLC12A2, the gene encoding the Na-K-2Cl cotransporter-1. The 11-bp deletion in exon 22 results in frameshift (p.Val1026Phefs*2) and truncation of the carboxy-terminal tail of the cotransporter. Preliminary studies in heterologous expression systems demonstrate that the mutation leads to a nonfunctional transporter, which is expressed and trafficked to the plasma membrane alongside wild-type NKCC1. The truncated protein, visible at higher molecular sizes, indicates either enhanced dimerization or misfolded aggregate. No significant dominant-negative effect was observed. K+ transport experiments performed in fibroblasts from the patient showed reduced total and NKCC1-mediated K+ influx. The absence of a bumetanide effect on K+ influx in patient fibroblasts only under hypertonic conditions suggests a deficit in NKCC1 regulation. We propose that disruption in NKCC1 function might affect sensory afferents and/or smooth muscle cells, as their functions depend on NKCC1 creating a Cl- gradient across the plasma membrane. This Cl- gradient allows the γ-aminobutyric acid (GABA) receptor or other Cl- channels to depolarize the membrane affecting processes such as neurotransmission or cell contraction. Under this hypothesis, disrupted sensory and smooth muscle function in a diverse set of tissues could explain the patient's phenotype.
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Affiliation(s)
- Eric Delpire
- Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA
| | - Lynne Wolfe
- Undiagnosed Diseases Program, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Bianca Flores
- Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA
| | - Rainelli Koumangoye
- Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA
| | - Cara C Schornak
- Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA
| | - Salma Omer
- Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA
| | - Barbara Pusey
- Undiagnosed Diseases Program, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Christopher Lau
- Undiagnosed Diseases Program, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Thomas Markello
- Undiagnosed Diseases Program, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - David R Adams
- Undiagnosed Diseases Program, National Institutes of Health, Bethesda, Maryland 20892, USA
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149
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Layton AT, Laghmani K, Vallon V, Edwards A. Solute transport and oxygen consumption along the nephrons: effects of Na+ transport inhibitors. Am J Physiol Renal Physiol 2016; 311:F1217-F1229. [PMID: 27707706 DOI: 10.1152/ajprenal.00294.2016] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Accepted: 09/28/2016] [Indexed: 01/11/2023] Open
Abstract
Sodium and its associated anions are the major determinant of extracellular fluid volume, and the reabsorption of Na+ by the kidney plays a crucial role in long-term blood pressure control. The goal of this study was to investigate the extent to which inhibitors of transepithelial Na+ transport (TNa) along the nephron alter urinary solute excretion and TNa efficiency and how those effects may vary along different nephron segments. To accomplish that goal, we used the multinephron model developed in the companion study (28). That model represents detailed transcellular and paracellular transport processes along the nephrons of a rat kidney. We simulated the inhibition of the Na+/H+ exchanger (NHE3), the bumetanide-sensitive Na+-K+-2Cl- transporter (NKCC2), the Na+-Cl- cotransporter (NCC), and the amiloride-sensitive Na+ channel (ENaC). Under baseline conditions, NHE3, NKCC2, NCC, and ENaC reabsorb 36, 22, 4, and 7%, respectively, of filtered Na+ The model predicted that inhibition of NHE3 substantially reduced proximal tubule TNa and oxygen consumption (QO2 ). Whole-kidney TNa efficiency, as reflected by the number of moles of Na+ reabsorbed per moles of O2 consumed (denoted by the ratio TNa/QO2 ), decreased by ∼20% with 80% inhibition of NHE3. NKCC2 inhibition simulations predicted a substantial reduction in thick ascending limb TNa and QO2 ; however, the effect on whole-kidney TNa/QO2 was minor. Tubular K+ transport was also substantially impaired, resulting in elevated urinary K+ excretion. The most notable effect of NCC inhibition was to increase the excretion of Na+, K+, and Cl-; its impact on whole-kidney TNa and its efficiency was minor. Inhibition of ENaC was predicted to have opposite effects on the excretion of Na+ (increased) and K+ (decreased) and to have only a minor impact on whole-kidney TNa and TNa/QO2 Overall, model predictions agree well with measured changes in Na+ and K+ excretion in response to diuretics and Na+ transporter mutations.
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Affiliation(s)
- Anita T Layton
- Department of Mathematics, Duke University, Durham, North Carolina;
| | - Kamel Laghmani
- Sorbonne Universités, UPMC Univ Paris 06, Université Paris Descartes, Sorbonne Paris Cité, INSERM UMRS 1138, CNRS ERL 8228, Centre de Recherche des Cordeliers, Paris, France; and
| | - Volker Vallon
- Departments of Medicine and Pharmacology, University of California San Diego, La Jolla, California, and San Diego Veterans Affairs Healthcare System, San Diego, California
| | - Aurélie Edwards
- Sorbonne Universités, UPMC Univ Paris 06, Université Paris Descartes, Sorbonne Paris Cité, INSERM UMRS 1138, CNRS ERL 8228, Centre de Recherche des Cordeliers, Paris, France; and
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150
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Sasaki S, Hasegawa K, Higashi T, Suzuki Y, Sugano S, Yasuda Y, Sugimoto Y. A missense mutation in solute carrier family 12, member 1 (SLC12A1) causes hydrallantois in Japanese Black cattle. BMC Genomics 2016; 17:724. [PMID: 27613513 PMCID: PMC5016959 DOI: 10.1186/s12864-016-3035-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2016] [Accepted: 08/24/2016] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND Hydrallantois is the excessive accumulation of fluid within the allantoic cavity in pregnant animals and is associated with fetal mortality. Although the incidence of hydrallantois is very low in artificial insemination breeding programs in cattle, recently 38 cows with the phenotypic appearance of hydrallantois were reported in a local subpopulation of Japanese Black cattle. Of these, 33 were traced back to the same sire; however, both their parents were reported healthy, suggesting that hydrallantois is a recessive inherited disorder. To identify autozygous chromosome segments shared by individuals with hydrallantois and the causative mutation in Japanese Black cattle, we performed autozygosity mapping using single-nucleotide polymorphism (SNP) array and exome sequencing. RESULTS Shared haplotypes of the affected fetuses spanned 3.52 Mb on bovine chromosome 10. Exome sequencing identified a SNP (g.62382825G > A, p.Pro372Leu) in exon 10 of solute carrier family 12, member 1 (SLC12A1), the genotype of which was compatible with recessive inheritance. SLC12A1 serves as a reabsorption molecule of Na(+)-K(+)-2Cl(-) in the apical membrane of the thick ascending limb of the loop of Henle in the kidney. We observed that the concentration of Na(+)-Cl(-) increased in allantoic fluid of homozygous SLC12A1 (g.62382825G > A) in a hydrallantois individual. In addition, SLC12A1-positive signals were localized at the apical membrane in the kidneys of unaffected fetuses, whereas they were absent from the apical membrane in the kidneys of affected fetuses. These results suggested that p.Pro372Leu affects the membrane localization of SLC12A1, and in turn, may impair its transporter activity. Surveillance of the risk-allele frequency revealed that the carriers were restricted to the local subpopulation of Japanese Black cattle. Moreover, we identified a founder individual that carried the mutation (g.62382825G > A). CONCLUSIONS In this study, we mapped the shared haplotypes of affected fetuses using autozygosity mapping and identified a de novo mutation in the SLC12A1 gene that was associated with hydrallantois in Japanese Black cattle. In kidneys of hydrallantois-affected fetuses, the mutation in SLC12A1 impaired the apical membrane localization of SLC12A1 and reabsorption of Na(+)-K(+)-2Cl(-) in the thick ascending limb of the loop of Henle, leading to a defect in the concentration of urine via the countercurrent mechanism. Consequently, the affected fetuses exhibited polyuria that accumulated in the allantoic cavity. Surveillance of the risk-allele frequency indicated that carriers were not widespread throughout the Japanese Black cattle population. Moreover, we identified the founder individual, and thus could effectively manage the disorder in the population.
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Affiliation(s)
- Shinji Sasaki
- Shirakawa Institute of Animal Genetics, Japan Livestock Technology Association, Odakura, Nishigo, Fukushima 961-8061 Japan
| | - Kiyotoshi Hasegawa
- Shimane Prefecture Livestock Technology Center, Koshi, Izumo, Shimane 693-0031 Japan
| | - Tomoko Higashi
- Shimane Prefecture Livestock Division Livestock Hygiene Research Office, Jinzaioki, Izumo, Shimane 699-0822 Japan
| | - Yutaka Suzuki
- Department of Medical Genome Sciences, and Department of Computational Biology, Graduate School of Frontier Sciences, The University of Tokyo, Chiba, 277-8562 Japan
| | - Sumio Sugano
- Department of Medical Genome Sciences, and Department of Computational Biology, Graduate School of Frontier Sciences, The University of Tokyo, Chiba, 277-8562 Japan
| | - Yasuaki Yasuda
- Shimane Prefecture Livestock Technology Center, Koshi, Izumo, Shimane 693-0031 Japan
| | - Yoshikazu Sugimoto
- Shirakawa Institute of Animal Genetics, Japan Livestock Technology Association, Odakura, Nishigo, Fukushima 961-8061 Japan
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