51
|
Fisher MM, Misurac JM, Leiser JD, Walvoord EC. Extreme Hypercalcemia of Malignancy in a Pediatric Patient: Therapeutic Considerations. AACE Clin Case Rep 2015. [DOI: 10.4158/ep14308.cr] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
|
52
|
Yasuoka Y, Sato Y, Healy JM, Nonoguchi H, Kawahara K. pH-sensitive expression of calcium-sensing receptor (CaSR) in type-B intercalated cells of the cortical collecting ducts (CCD) in mouse kidney. Clin Exp Nephrol 2014; 19:771-82. [PMID: 25500736 DOI: 10.1007/s10157-014-1063-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Accepted: 11/22/2014] [Indexed: 12/18/2022]
Abstract
BACKGROUND The localization and role of the calcium-sensing receptor (CaSR) along the nephron including the collecting ducts is still open to debate. METHODS Using the quantitative, highly sensitive in situ hybridization technique and a double-staining immunohistochemistry technique, we investigated the axial distribution and expression of CaSR along the nephron in mice (C57B/6J) treated for 6 days with acid or alkali diets. RESULTS Under control condition, CaSR was specifically localized in the cortical and medullary thick ascending limb of Henle's loop (CTAL and MTAL), macula densa (MD), distal convoluted tubule (DCT), and CCD (TALs, MD > DCT, CCD). Along the CCD, CaSR was co-localized with an anion exchanger type 4 (AE4), a marker of the basolateral membrane of type-B intercalated cell (IC-B) in mice. On the contrary, CaSR was not detected either in principal cells (PC) or in type-A intercalated cell (IC-A). CaSR expression levels in IC-B significantly (P < 0.005) decreased when mice were fed NH4Cl (acid) diets and increased when animals were given NaHCO3 (alkali) diets. As expected, cell heights of IC-A and IC-B significantly (P < 0.005) increased in the above experimental conditions. Surprisingly, single infusion (ip) of neomycin, an agonist of CaSR, significantly (P < 0.005) increased urinary Ca excretion without further increasing the hourly urine volume and significantly (P < 0.05) decreased urine pH. CONCLUSION CaSR, cloned from rat kidney, was localized in the basolateral membrane of IC-B and was more expressed during alkali-loading. Its alkali-sensitive expression may promote urinary alkali secretion for body acid-base balance.
Collapse
Affiliation(s)
- Yukiko Yasuoka
- Department of Physiology, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami-ku, Sagamihara, 252-0374, Japan.,Department of Cellular and Molecular Physiology, Kitasato University Graduate School of Medical Sciences, Sagamihara, 252-0374, Japan
| | - Yuichi Sato
- Department of Molecular Diagnostics, Kitasato University School of Allied Health Sciences, Sagamihara, 252-0374, Japan
| | - Jillian M Healy
- ALESS Program, Komaba Organizational for Educational Excellence, College of Art and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902, Japan
| | - Hiroshi Nonoguchi
- Division of Internal Medicine, Kitasato University Medical Center, 6-100 Arai, Kitamoto, 364-8501, Japan
| | - Katsumasa Kawahara
- Department of Physiology, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami-ku, Sagamihara, 252-0374, Japan. .,Department of Cellular and Molecular Physiology, Kitasato University Graduate School of Medical Sciences, Sagamihara, 252-0374, Japan.
| |
Collapse
|
53
|
Alfadda TI, Saleh AMA, Houillier P, Geibel JP. Calcium-sensing receptor 20 years later. Am J Physiol Cell Physiol 2014; 307:C221-31. [PMID: 24871857 PMCID: PMC4121584 DOI: 10.1152/ajpcell.00139.2014] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Accepted: 05/23/2014] [Indexed: 12/19/2022]
Abstract
The calcium-sensing receptor (CaSR) has played an important role as a target in the treatment of a variety of disease states over the past 20 plus years. In this review, we give an overview of the receptor at the cellular level and then provide details as to how this receptor has been targeted to modulate cellular ion transport mechanisms. As a member of the G protein-coupled receptor (GPCR) family, it has a high degree of homology with a variety of other members in this class, which could explain why this receptor has been identified in so many different tissues throughout the body. This diversity of locations sets it apart from other members of the family and may explain how the receptor interacts with so many different organ systems in the body to modulate the physiology and pathophysiology. The receptor is unique in that it has two large exofacial lobes that sit in the extracellular environment and sense changes in a wide variety of environmental cues including salinity, pH, amino acid concentration, and polyamines to name just a few. It is for this reason that there has been a great deal of research associated with normal receptor physiology over the past 20 years. With the ongoing research, in more recent years a focus on the pathophysiology has emerged and the effects of receptor mutations on cellular and organ physiology have been identified. We hope that this review will enhance and update the knowledge about the importance of this receptor and stimulate future potential investigations focused around this receptor in cellular, organ, and systemic physiology and pathophysiology.
Collapse
Affiliation(s)
- Tariq I Alfadda
- Department of Surgery, Yale School of Medicine, New Haven, Connecticut
| | - Ahmad M A Saleh
- Department of Surgery, Yale School of Medicine, New Haven, Connecticut
| | - Pascal Houillier
- INSERM UMR_S1138, Paris, France; Paris Descartes University, Paris, France; Assistance Publique-Hopitaux de Paris, Hopital Europeen Georges Pompidou, Paris, France
| | - John P Geibel
- Department of Surgery, Yale School of Medicine, New Haven, Connecticut; Department of Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut; and
| |
Collapse
|
54
|
Besiroglu H, Sahin S, Otunctemur A, Ozbek E. Calcium-sensing receptor gene polymorphisms in patients with calcium urolithiasis: a systematic review. Ren Fail 2014; 36:1187-92. [PMID: 25019182 DOI: 10.3109/0886022x.2014.937673] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Calcium-sensing receptor gene (CaSR) might be a strong component of the complex genetic background regulating calcium excretion and stone formation in kidney. The polymorphisms in different parts of the gene could be associated with calcium stone formation. OBJECTIVE The individual studies indicate a correlation between CaSR gene polymorphisms and urolithiasis but not sufficient to draw a precise result. We aimed to search literature to come to a reliable conclusion through a systematic review. MATERIALS AND METHODS We have serached individiual studies regarding the issue and high quality reviews. We assessed all the studies to draw a conclusion. CONCLUSION The genetic background of the neprolithiasis is an interesting issue deserving to be disscussed on. Regading genes of which, CaSR gene polymorphisms is the leading one, are studied in many individual studies but they are not sufficient to have a precise conclusion. Well-oriented and documented, phenotypically homogenous large cohort studies are needed for further evaluation.
Collapse
Affiliation(s)
- Huseyin Besiroglu
- Department of Urology, Okmeydani Training and Research Hospital , Istanbul , Turkey
| | | | | | | |
Collapse
|
55
|
Sim JH, Himmel NJ, Redd SK, Pulous FE, Rogers RT, Black LN, Hong SM, von Bergen TN, Blount MA. Absence of PKC-alpha attenuates lithium-induced nephrogenic diabetes insipidus. PLoS One 2014; 9:e101753. [PMID: 25006961 PMCID: PMC4090211 DOI: 10.1371/journal.pone.0101753] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Accepted: 06/11/2014] [Indexed: 01/01/2023] Open
Abstract
Lithium, an effective antipsychotic, induces nephrogenic diabetes insipidus (NDI) in ∼40% of patients. The decreased capacity to concentrate urine is likely due to lithium acutely disrupting the cAMP pathway and chronically reducing urea transporter (UT-A1) and water channel (AQP2) expression in the inner medulla. Targeting an alternative signaling pathway, such as PKC-mediated signaling, may be an effective method of treating lithium-induced polyuria. PKC-alpha null mice (PKCα KO) and strain-matched wild type (WT) controls were treated with lithium for 0, 3 or 5 days. WT mice had increased urine output and lowered urine osmolality after 3 and 5 days of treatment whereas PKCα KO mice had no change in urine output or concentration. Western blot analysis revealed that AQP2 expression in medullary tissues was lowered after 3 and 5 days in WT mice; however, AQP2 was unchanged in PKCα KO. Similar results were observed with UT-A1 expression. Animals were also treated with lithium for 6 weeks. Lithium-treated WT mice had 19-fold increased urine output whereas treated PKCα KO animals had a 4-fold increase in output. AQP2 and UT-A1 expression was lowered in 6 week lithium-treated WT animals whereas in treated PKCα KO mice, AQP2 was only reduced by 2-fold and UT-A1 expression was unaffected. Urinary sodium, potassium and calcium were elevated in lithium-fed WT but not in lithium-fed PKCα KO mice. Our data show that ablation of PKCα preserves AQP2 and UT-A1 protein expression and localization in lithium-induced NDI, and prevents the development of the severe polyuria associated with lithium therapy.
Collapse
Affiliation(s)
- Jae H. Sim
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Nathaniel J. Himmel
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Sara K. Redd
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Fadi E. Pulous
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Richard T. Rogers
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Lauren N. Black
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Seongun M. Hong
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Tobias N. von Bergen
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Mitsi A. Blount
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, United States of America
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia, United States of America
| |
Collapse
|
56
|
Risk of nephrolithiasis in primary hyperparathyroidism is associated with two polymorphisms of the calcium-sensing receptor gene. J Nephrol 2014; 28:67-72. [PMID: 24832896 DOI: 10.1007/s40620-014-0106-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Accepted: 04/28/2014] [Indexed: 10/25/2022]
Abstract
AIMS Two single-nucleotide polymorphisms (SNPs) at the calcium-sensing receptor (CASR) gene were previously associated with kidney stones in patients with primary hyperparathyroidism (PHPT): rs1501899, likely associated with a decrease in CASR expression, and Arg990Gly, causing a gain of CASR function. To evaluate the interaction of these two SNPs in the stone risk, we tested the association of stones with the genotype at both SNPs in PHPT patients and the association of rs1501899 with CASR expression as messenger RNA (mRNA) in human kidney samples. METHODS AND RESULTS Two hundred and ninety-six PHPT patients were genotyped at the rs1501899 and Arg990Gly SNPs. Minor allele frequency at tested SNPs was higher in PHPT stone formers relative to non-stone forming patients. PHPT patients carrying one or two copies of the minor allele at both rs1501899 and Arg990Gly (n = 16) had the maximal risk of stones (odds ratio, OR 8.3) and higher serum ionized calcium compared with homozygous patients for the wild-type allele at both SNPs. CASR expression as mRNA was measured by real time polymerase chain reaction (PCR) in normal kidney medulla samples from 109 subjects. CASR mRNA was significantly lower in medulla samples from homozygotes for the minor allele at rs1501899 than in subjects with other genotypes. CONCLUSIONS We conclude that the simultaneous presence of the minor allele at rs1501899 and Arg990Gly may amplify the kidney stone risk in PHPT patients, despite their apparently opposite effects on CASR function in the kidney.
Collapse
|
57
|
Abstract
Capasso et al. show a role of the calcium-sensing receptor (CaSR) in enhancing proximal tubular fluid absorption and urinary acidification by stimulation of luminal Na(+)/H(+) exchanger (NHE) activity. NHE3 is required for sodium and fluid absorption, and its activity is coupled to passive reabsorption of a major fraction of calcium through the paracellular route. These data shed new light on the regulation of the kidney by the CaSR and whether it directly affects proximal tubular functions.
Collapse
|
58
|
Abstract
PURPOSE OF REVIEW Changes in extracellular calcium concentration affect several functions of the renal tubule. The calcium-sensing receptor (CaSR), initially identified in the parathyroid gland cells, is also expressed in the kidney and was assumed to mediate all effects of extracellular calcium on the renal tubule. The purpose of this review is to critically review the evidence supporting this assumption. RECENT FINDINGS Recent results confirm that, in the kidney, the CaSR is mainly expressed in the thick ascending limb of the loop of Henle. There, it is involved in the control of calcium reabsorption, independently of its action on parathyroid hormone secretion, through an effect on the paracellular pathway permeability. Although extracellular calcium affects transports other than that of calcium, the direct evidence that CaSR is involved in these effects is still lacking in many instances. SUMMARY As the CaSR in the kidney controls calcium reabsorption and excretion and subsequently affects blood calcium concentration, agonists and antagonists of the CaSR could be used to control blood calcium concentration in patients who have lost their ability to regulate parathyroid hormone secretion. In addition, more work is needed to further decipher the molecular mechanisms through which CaSR determines calcium transport in the loop of Henle.
Collapse
|
59
|
Abstract
TRPV5 is one of the two channels in the TRPV family that exhibit high selectivity to Ca(2+) ions. TRPV5 mediates Ca(2+) influx into cells as the first step to transport Ca(2+) across epithelia. The specialized distribution in the distal tubule of the kidney positions TRPV5 as a key player in Ca(2+) reabsorption. The responsiveness in expression and/or activity of TRPV5 to hormones such as 1,25-dihydroxyvitamin D3, parathyroid hormone, estrogen, and testosterone makes TRPV5 suitable for its role in the fine-tuning of Ca(2+) reabsorption. This role is further optimized by the modulation of TRPV5 trafficking and activity via its binding partners; co-expressed proteins; tubular factors such as calbindin-D28k, calmodulin, klotho, uromodulin, and plasmin; extracellular and intracellular factors such as proton, Mg(2+), Ca(2+), and phosphatidylinositol-4,5-bisphosphate; and fluid flow. These regulations allow TRPV5 to adjust its overall activity in response to the body's demand for Ca(2+) and to prevent kidney stone formation. A point mutation in mouse Trpv5 gene leads to hypercalciuria similar to Trpv5 knockout mice, suggesting a possible role of TRPV5 in hypercalciuric disorders in humans. In addition, the single nucleotide polymorphisms in Trpv5 gene prevalently present in African descents may contribute to the efficient renal Ca(2+) reabsorption among African descendants. TRPV5 represents a potential therapeutic target for disorders with altered Ca(2+) homeostasis.
Collapse
Affiliation(s)
- Tao Na
- Cell Collection and Research Center, Institute for Biological Product Control, National Institutes for Food and Drug Control, Beijing, China
| | | |
Collapse
|
60
|
Casare F, Milan D, Fernandez R. Stimulation of calcium-sensing receptor increases biochemical H⁺-ATPase activity in mouse cortex and outer medullary regions. Can J Physiol Pharmacol 2013; 92:181-8. [PMID: 24593782 DOI: 10.1139/cjpp-2013-0256] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The aim of this project was to investigate the interaction between the calcium-sensing receptor (CaSR) and proton extrusion by the V-ATPase and gastric-like isoform of the H(+)/K(+)-ATPase in the mouse nephron. Biochemical activity of H(+)- ATPases was analysed using a partially purified membrane fraction of mouse cortex and outer medullary region. The V-ATPase activity (sensitive to 10(-7) mol·L(-1) bafilomycin) from the cortical and outer medullary region was significantly stimulated by increasing the [Formula: see text] (outside Ca(2+)), in a dose-dependent pattern. Gastric H(+)/K(+)-ATPase activity (sensitive to 10(-5) mol·L(-1) Schering 28080) was also sensitive to changes in [Formula: see text] levels. A significant increase in V-ATPase activity was also observed when CaSR was stimulated with agonists such as 300 μmol·L(-1) Gd(3+) and 200 μmol·L(-1) neomycin, both in the cortex and outer medulla. The cortical and outer medullary gastric H(+)/K(+)-ATPase activity was also stimulated by Gd(3+) and neomycin. Finally, cortical V-ATPase activity was significantly stimulated by 10(-9) mol·L(-1) angiotensin II, and the stimulation of CaSR in the presence of angiotensin significantly enhanced this effect, suggesting that an interaction in the intracellular signaling pathways is involved. In summary, CaSR stimulation enhances the biochemical activity of V-ATPase and gastric H(+)/K(+)-ATPase in both the cortical and outer medullary region of mouse kidney.
Collapse
Affiliation(s)
- Fernando Casare
- Departamento de Fisiologia, Setor de Ciências Biológicas, Universidade Federal do Paraná (UFPR), Centro Politécnico s/n., PO Box 19031, Jardim das Américas, Curitiba, Paraná, CEP 81531-990, Brasil
| | | | | |
Collapse
|
61
|
Christensen EI, Wagner CA, Kaissling B. Uriniferous tubule: structural and functional organization. Compr Physiol 2013; 2:805-61. [PMID: 23961562 DOI: 10.1002/cphy.c100073] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The uriniferous tubule is divided into the proximal tubule, the intermediate (thin) tubule, the distal tubule and the collecting duct. The present chapter is based on the chapters by Maunsbach and Christensen on the proximal tubule, and by Kaissling and Kriz on the distal tubule and collecting duct in the 1992 edition of the Handbook of Physiology, Renal Physiology. It describes the fine structure (light and electron microscopy) of the entire mammalian uriniferous tubule, mainly in rats, mice, and rabbits. The structural data are complemented by recent data on the location of the major transport- and transport-regulating proteins, revealed by morphological means(immunohistochemistry, immunofluorescence, and/or mRNA in situ hybridization). The structural differences along the uriniferous tubule strictly coincide with the distribution of the major luminal and basolateral transport proteins and receptors and both together provide the basis for the subdivision of the uriniferous tubule into functional subunits. Data on structural adaptation to defined functional changes in vivo and to genetical alterations of specified proteins involved in transepithelial transport importantly deepen our comprehension of the correlation of structure and function in the kidney, of the role of each segment or cell type in the overall renal function,and our understanding of renal pathophysiology.
Collapse
|
62
|
Vezzoli G, Terranegra A, Aloia A, Arcidiacono T, Milanesi L, Mosca E, Mingione A, Spotti D, Cusi D, Hou J, Hendy GN, Soldati L, Paloschi V, Dogliotti E, Brasacchio C, Dell'Antonio G, Montorsi F, Bertini R, Bellinzoni P, Guazzoni G, Borghi L, Guerra A, Allegri F, Ticinesi A, Meschi T, Nouvenne A, Lupo A, Fabris A, Gambaro G, Strazzullo P, Rendina D, De Filippo G, Brandi ML, Croppi E, Cianferotti L, Trinchieri A, Caudarella R, Cupisti A, Anglani F, Del Prete D. Decreased transcriptional activity of calcium-sensing receptor gene promoter 1 is associated with calcium nephrolithiasis. J Clin Endocrinol Metab 2013; 98:3839-47. [PMID: 23864702 PMCID: PMC3763974 DOI: 10.1210/jc.2013-1834] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
BACKGROUND CaSR gene is a candidate for calcium nephrolithiasis. Single-nucleotide polymorphisms (SNPs) encompassing its regulatory region were associated with calcium nephrolithiasis. AIMS We tested SNPs in the CaSR gene regulatory region associated with calcium nephrolithiasis and their effects in kidney. SUBJECTS AND METHODS One hundred sixty-seven idiopathic calcium stone formers and 214 healthy controls were genotyped for four CaSR gene SNPs identified by bioinformatics analysis as modifying transcription factor binding sites. Strontium excretion after an oral load was tested in 55 stone formers. Transcriptional activity induced by variant alleles at CaSR gene promoters was compared by luciferase reporter gene assay in HEK-293 and HKC-8 cells. CaSR and claudin-14 mRNA levels were measured by real-time PCR in 107 normal kidney medulla samples and compared in patients with different CaSR genotype. RESULTS Only rs6776158 (A>G), located in the promoter 1, was associated with nephrolithiasis. Its minor G allele was more frequent in stone formers than controls (37.8% vs 26.4%, P = .001). A reduced strontium excretion was observed in GG homozygous stone formers. Luciferase fluorescent activity was lower in cells transfected with the promoter 1 including G allele at rs6776158 than cells transfected with the A allele. CaSR mRNA levels were lower in kidney medulla samples from homozygous carriers for the G allele at rs6776158 than carriers for the A allele. Claudin-14 mRNA levels were also lower in GG homozygous subjects. CONCLUSIONS Minor allele at rs6776158 may predispose to calcium stones by decreasing transcriptional activity of the CaSR gene promoter 1 and CaSR expression in kidney tubules.
Collapse
Affiliation(s)
- Giuseppe Vezzoli
- Nephrology and Dialysis Unit, San Raffaele Hospital Instituto di Ricovero e Cura a Carattere Scientifico, 20132 Milan, Italy.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
63
|
Disorders of calcium and magnesium balance: a physiology-based approach. Pediatr Nephrol 2013; 28:1195-206. [PMID: 23142866 DOI: 10.1007/s00467-012-2350-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Revised: 10/02/2012] [Accepted: 10/08/2012] [Indexed: 01/20/2023]
Abstract
Disorders of calcium and magnesium balance are physiologically interesting and clinically challenging. In this review, we attempt to bridge the gap between physiology and practice by providing a physiology-based approach to understanding hypocalcemia, hypercalcemia and hypomagnesemia. Calcium and, to a lesser extent, magnesium balance is achieved through a complex interplay between the parathyroid gland, bone, the intestine and the kidney. Our understanding of the molecular physiology of calcium and magnesium balance has grown considerably following the discovery of the calcium-sensing receptor (CaSR) and the main intestinal and renal transporters for calcium and magnesium, namely, the transient receptor potential channels TRPV5, TRPV6 and TRPM6. The regulation of parathyroid hormone (PTH) secretion by CaSR and the subsequent effects of PTH and vitamin D on TRPV5 constitute an increasingly characterized regulatory loop. In contrast, no truly magnesiotropic hormones have been identified, although the recently established interactions between the epidermal growth factor and TRPM6 suggest a possible candidate. Overall, the aim of this review is to illustrate the clinical disorders of calcium and magnesium balance from the perspective of their integrated physiology.
Collapse
|
64
|
Tyler Miller R. Control of renal calcium, phosphate, electrolyte, and water excretion by the calcium-sensing receptor. Best Pract Res Clin Endocrinol Metab 2013; 27:345-58. [PMID: 23856264 DOI: 10.1016/j.beem.2013.04.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Through regulation of excretion, the kidney shares responsibility for the metabolic balance of calcium (Ca(2+)) with several other tissues including the GI tract and bone. The balances of Ca(2+) and phosphate (PO4), magnesium (Mg(2+)), sodium (Na(+)), potassium (K(+)), chloride (Cl(-)), and water (H2O) are linked via regulatory systems with overlapping effects and are also controlled by systems specific to each of them. Cloning of the calcium-sensing receptor (CaSR) along with the recognition that mutations in the CaSR gene are responsible for two familial syndromes characterized by abnormalities in the regulation of PTH secretion and Ca(2+) metabolism (Familial Hypocalciuric Hypercalcemia, FHH, and Autosomal Dominant Hypocalcemia, ADH) made it clear that extracellular Ca(2+) (Ca(2+)o) participates in its own regulation via a specific, receptor-mediated mechanism. Demonstration that the CaSR is expressed in the kidney as well as the parathyroid glands combined with more complete characterizations of FHH and ADH established that the effects of elevated Ca(2+) on the kidney (wasting of Na(+), K(+), Cl(-), Ca(2+), Mg(2+) and H2O) are attributable to activation of the CaSR. The advent of positive and negative allosteric modulators of the CaSR along with mouse models with global or tissue-selective deletion of the CaSR in the kidney have allowed a better understanding of the functions of the CaSR in various nephron segments. The biology of the CaSR is more complicated than originally thought and difficult to define precisely owing to the limitations of reagents such as anti-CaSR antibodies and the difficulties inherent in separating direct effects of Ca(2+) on the kidney mediated by the CaSR from associated CaSR-induced changes in PTH. Nevertheless, renal CaSRs have nephron-specific effects that contribute to regulating Ca(2+) in the circulation and urine in a manner that assures a narrow range of Ca(2+)o in the blood and avoids excessively high concentrations of Ca(2+) in the urine.
Collapse
Affiliation(s)
- R Tyler Miller
- Department of Medicine and Nephrology, University of Texas Southwestern Medical Center and Chief of Medicine Service, VA North Texas Health System, 5323 Harry Hines Blvd, Dallas, TX 75390, USA.
| |
Collapse
|
65
|
Calcium regulation and bone mineral metabolism in elderly patients with chronic kidney disease. Nutrients 2013; 5:1913-36. [PMID: 23760058 PMCID: PMC3725483 DOI: 10.3390/nu5061913] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Revised: 04/25/2013] [Accepted: 05/08/2013] [Indexed: 12/20/2022] Open
Abstract
The elderly chronic kidney disease (CKD) population is growing. Both aging and CKD can disrupt calcium (Ca2+) homeostasis and cause alterations of multiple Ca2+-regulatory mechanisms, including parathyroid hormone, vitamin D, fibroblast growth factor-23/Klotho, calcium-sensing receptor and Ca2+-phosphate product. These alterations can be deleterious to bone mineral metabolism and soft tissue health, leading to metabolic bone disease and vascular calcification and aging, termed CKD-mineral and bone disorder (MBD). CKD-MBD is associated with morbid clinical outcomes, including fracture, cardiovascular events and all-cause mortality. In this paper, we comprehensively review Ca2+ regulation and bone mineral metabolism, with a special emphasis on elderly CKD patients. We also present the current treatment-guidelines and management options for CKD-MBD.
Collapse
|
66
|
Kopic S, Geibel JP. Gastric acid, calcium absorption, and their impact on bone health. Physiol Rev 2013; 93:189-268. [PMID: 23303909 DOI: 10.1152/physrev.00015.2012] [Citation(s) in RCA: 102] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Calcium balance is essential for a multitude of physiological processes, ranging from cell signaling to maintenance of bone health. Adequate intestinal absorption of calcium is a major factor for maintaining systemic calcium homeostasis. Recent observations indicate that a reduction of gastric acidity may impair effective calcium uptake through the intestine. This article reviews the physiology of gastric acid secretion, intestinal calcium absorption, and their respective neuroendocrine regulation and explores the physiological basis of a potential link between these individual systems.
Collapse
Affiliation(s)
- Sascha Kopic
- Department of Surgery and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut, USA
| | | |
Collapse
|
67
|
Loh NY, Bentley L, Dimke H, Verkaart S, Tammaro P, Gorvin CM, Stechman MJ, Ahmad BN, Hannan FM, Piret SE, Evans H, Bellantuono I, Hough TA, Fraser WD, Hoenderop JGJ, Ashcroft FM, Brown SDM, Bindels RJM, Cox RD, Thakker RV. Autosomal dominant hypercalciuria in a mouse model due to a mutation of the epithelial calcium channel, TRPV5. PLoS One 2013; 8:e55412. [PMID: 23383183 PMCID: PMC3559602 DOI: 10.1371/journal.pone.0055412] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Accepted: 12/22/2012] [Indexed: 12/05/2022] Open
Abstract
Hypercalciuria is a major cause of nephrolithiasis, and is a common and complex disorder involving genetic and environmental factors. Identification of genetic factors for monogenic forms of hypercalciuria is hampered by the limited availability of large families, and to facilitate such studies, we screened for hypercalciuria in mice from an N-ethyl-N-nitrosourea mutagenesis programme. We identified a mouse with autosomal dominant hypercalciuria (HCALC1). Linkage studies mapped the Hcalc1 locus to a 11.94 Mb region on chromosome 6 containing the transient receptor potential cation channel, subfamily V, members 5 (Trpv5) and 6 (Trpv6) genes. DNA sequence analysis of coding regions, intron-exon boundaries and promoters of Trpv5 and Trpv6 identified a novel T to C transition in codon 682 of TRPV5, mutating a conserved serine to a proline (S682P). Compared to wild-type littermates, heterozygous (Trpv5682P/+) and homozygous (Trpv5682P/682P) mutant mice had hypercalciuria, polyuria, hyperphosphaturia and a more acidic urine, and ∼10% of males developed tubulointerstitial nephritis. Trpv5682P/682P mice also had normal plasma parathyroid hormone but increased 1,25-dihydroxyvitamin D3 concentrations without increased bone resorption, consistent with a renal defect for the hypercalciuria. Expression of the S682P mutation in human embryonic kidney cells revealed that TRPV5-S682P-expressing cells had a lower baseline intracellular calcium concentration than wild-type TRPV5-expressing cells, suggesting an altered calcium permeability. Immunohistological studies revealed a selective decrease in TRPV5-expression from the renal distal convoluted tubules of Trpv5682P/+ and Trpv5682P/682P mice consistent with a trafficking defect. In addition, Trpv5682P/682P mice had a reduction in renal expression of the intracellular calcium-binding protein, calbindin-D28K, consistent with a specific defect in TRPV5-mediated renal calcium reabsorption. Thus, our findings indicate that the TRPV5 S682P mutant is functionally significant and study of HCALC1, a novel model for autosomal dominant hypercalciuria, may help further our understanding of renal calcium reabsorption and hypercalciuria.
Collapse
Affiliation(s)
- Nellie Y. Loh
- Academic Endocrine Unit, Nuffield Department of Medicine, University of Oxford, Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), Churchill Hospital, Headington, Oxford, United Kingdom
| | - Liz Bentley
- MRC Mammalian Genetics Unit and Mary Lyon Centre, Medical Research Council, Harwell, Oxfordshire, United Kingdom
| | - Henrik Dimke
- Department of Physiology, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Sjoerd Verkaart
- Department of Physiology, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Paolo Tammaro
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Caroline M. Gorvin
- Academic Endocrine Unit, Nuffield Department of Medicine, University of Oxford, Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), Churchill Hospital, Headington, Oxford, United Kingdom
| | - Michael J. Stechman
- Academic Endocrine Unit, Nuffield Department of Medicine, University of Oxford, Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), Churchill Hospital, Headington, Oxford, United Kingdom
| | - Bushra N. Ahmad
- Academic Endocrine Unit, Nuffield Department of Medicine, University of Oxford, Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), Churchill Hospital, Headington, Oxford, United Kingdom
| | - Fadil M. Hannan
- Academic Endocrine Unit, Nuffield Department of Medicine, University of Oxford, Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), Churchill Hospital, Headington, Oxford, United Kingdom
| | - Sian E. Piret
- Academic Endocrine Unit, Nuffield Department of Medicine, University of Oxford, Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), Churchill Hospital, Headington, Oxford, United Kingdom
| | - Holly Evans
- Academic Unit of Bone Biology, University of Sheffield, The Medical School, Sheffield, United Kingdom
| | - Ilaria Bellantuono
- Academic Unit of Bone Biology, University of Sheffield, The Medical School, Sheffield, United Kingdom
| | - Tertius A. Hough
- MRC Mammalian Genetics Unit and Mary Lyon Centre, Medical Research Council, Harwell, Oxfordshire, United Kingdom
| | - William D. Fraser
- Faculty of Medical and Health Sciences, University of East Anglia, Norwich Research Park, Norwich, United Kingdom
| | - Joost G. J. Hoenderop
- Department of Physiology, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Frances M. Ashcroft
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Steve D. M. Brown
- MRC Mammalian Genetics Unit and Mary Lyon Centre, Medical Research Council, Harwell, Oxfordshire, United Kingdom
| | - René J. M. Bindels
- Department of Physiology, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Roger D. Cox
- MRC Mammalian Genetics Unit and Mary Lyon Centre, Medical Research Council, Harwell, Oxfordshire, United Kingdom
| | - Rajesh V. Thakker
- Academic Endocrine Unit, Nuffield Department of Medicine, University of Oxford, Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), Churchill Hospital, Headington, Oxford, United Kingdom
- * E-mail:
| |
Collapse
|
68
|
|
69
|
van der Eerden BC, Fratzl-Zelman N, Nijenhuis T, Roschger P, Zügel U, Steinmeyer A, Hoenderop JG, Bindels RJ, Klaushofer K, van Leeuwen JP. The vitamin D analog ZK191784 normalizes decreased bone matrix mineralization in mice lacking the calcium channel TRPV5. J Cell Physiol 2012; 228:402-7. [DOI: 10.1002/jcp.24144] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
|
70
|
Calcium-sensing receptor gene polymorphisms in patients with calcium nephrolithiasis. Curr Opin Nephrol Hypertens 2012; 21:355-61. [PMID: 22660550 DOI: 10.1097/mnh.0b013e3283542290] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW The calcium-sensing receptor gene (CaSR, chr. 3q13.3-21) is a candidate to explain nephrolithiasis. This review analyzes the potential role of CaSR in lithogenesis according to findings of functional and genetic studies. RECENT FINDINGS CaSR is a cation receptor located in the tubular cell plasma membrane. Its activation decreases calcium reabsorption in the ascending limb and distal convoluted tubule, but increases phosphate reabsorption in proximal tubules and decreases water and proton reabsorption in collecting ducts. Its effects in proximal tubules and collecting ducts can limit the calcium phosphate precipitation risk induced by the increase in calcium excretion. The nonconservative CaSR gene Arg990Gly polymorphism was associated with nephrolithiasis and hypercalciuria in different populations. Arg990Gly is located on exon 7 and produces a gain of the CaSR function. rs7652589 and rs1501899 were also associated with nephrolithiasis in patients with normal citrate excretion. These polymorphisms are located in the CaSR gene regulatory region and may modify CaSR gene promoter activity. SUMMARY The activating Arg990Gly polymorphism may predispose to nephrolithiasis by increasing calcium excretion. Polymorphisms at the regulatory region may predispose to nephrolithiasis by changing tubular expression of the CaSR. CaSR genotype may be a marker to identify patients prone to develop calcium nephrolithiasis.
Collapse
|
71
|
Toka HR, Al-Romaih K, Koshy JM, DiBartolo S, Kos CH, Quinn SJ, Curhan GC, Mount DB, Brown EM, Pollak MR. Deficiency of the calcium-sensing receptor in the kidney causes parathyroid hormone-independent hypocalciuria. J Am Soc Nephrol 2012; 23:1879-90. [PMID: 22997254 DOI: 10.1681/asn.2012030323] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Rare loss-of-function mutations in the calcium-sensing receptor (Casr) gene lead to decreased urinary calcium excretion in the context of parathyroid hormone (PTH)-dependent hypercalcemia, but the role of Casr in the kidney is unknown. Using animals expressing Cre recombinase driven by the Six2 promoter, we generated mice that appeared grossly normal but had undetectable levels of Casr mRNA and protein in the kidney. Baseline serum calcium, phosphorus, magnesium, and PTH levels were similar to control mice. When challenged with dietary calcium supplementation, however, these mice had significantly lower urinary calcium excretion than controls (urinary calcium to creatinine, 0.31±0.03 versus 0.63±0.14; P=0.001). Western blot analysis on whole-kidney lysates suggested an approximately four-fold increase in activated Na(+)-K(+)-2Cl(-) cotransporter (NKCC2). In addition, experimental animals exhibited significant downregulation of Claudin14, a negative regulator of paracellular cation permeability in the thick ascending limb, and small but significant upregulation of Claudin16, a positive regulator of paracellular cation permeability. Taken together, these data suggest that renal Casr regulates calcium reabsorption in the thick ascending limb, independent of any change in PTH, by increasing the lumen-positive driving force for paracellular Ca(2+) transport.
Collapse
Affiliation(s)
- Hakan R Toka
- Division of Nephrology, Beth Israel Medical Center, 330 Brookline Avenue, Boston, MA 02115, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
72
|
Loupy A, Ramakrishnan SK, Wootla B, Chambrey R, de la Faille R, Bourgeois S, Bruneval P, Mandet C, Christensen EI, Faure H, Cheval L, Laghmani K, Collet C, Eladari D, Dodd RH, Ruat M, Houillier P. PTH-independent regulation of blood calcium concentration by the calcium-sensing receptor. J Clin Invest 2012. [PMID: 22886306 DOI: 10.1172/jci57407.] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Tight regulation of calcium levels is required for many critical biological functions. The Ca2+-sensing receptor (CaSR) expressed by parathyroid cells controls blood calcium concentration by regulating parathyroid hormone (PTH) secretion. However, CaSR is also expressed in other organs, such as the kidney, but the importance of extraparathyroid CaSR in calcium metabolism remains unknown. Here, we investigated the role of extraparathyroid CaSR using thyroparathyroidectomized, PTH-supplemented rats. Chronic inhibition of CaSR selectively increased renal tubular calcium absorption and blood calcium concentration independent of PTH secretion change and without altering intestinal calcium absorption. CaSR inhibition increased blood calcium concentration in animals pretreated with a bisphosphonate, indicating that the increase did not result from release of bone calcium. Kidney CaSR was expressed primarily in the thick ascending limb of the loop of Henle (TAL). As measured by in vitro microperfusion of cortical TAL, CaSR inhibitors increased calcium reabsorption and paracellular pathway permeability but did not change NaCl reabsorption. We conclude that CaSR is a direct determinant of blood calcium concentration, independent of PTH, and modulates renal tubular calcium transport in the TAL via the permeability of the paracellular pathway. These findings suggest that CaSR inhibitors may provide a new specific treatment for disorders related to impaired PTH secretion, such as primary hypoparathyroidism.
Collapse
Affiliation(s)
- Alexandre Loupy
- INSERM UMRS 872, Centre de Recherche des Cordeliers, Paris, France
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
73
|
Loupy A, Ramakrishnan SK, Wootla B, Chambrey R, de la Faille R, Bourgeois S, Bruneval P, Mandet C, Christensen EI, Faure H, Cheval L, Laghmani K, Collet C, Eladari D, Dodd RH, Ruat M, Houillier P. PTH-independent regulation of blood calcium concentration by the calcium-sensing receptor. J Clin Invest 2012; 122:3355-67. [PMID: 22886306 DOI: 10.1172/jci57407] [Citation(s) in RCA: 142] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2011] [Accepted: 06/28/2012] [Indexed: 12/27/2022] Open
Abstract
Tight regulation of calcium levels is required for many critical biological functions. The Ca2+-sensing receptor (CaSR) expressed by parathyroid cells controls blood calcium concentration by regulating parathyroid hormone (PTH) secretion. However, CaSR is also expressed in other organs, such as the kidney, but the importance of extraparathyroid CaSR in calcium metabolism remains unknown. Here, we investigated the role of extraparathyroid CaSR using thyroparathyroidectomized, PTH-supplemented rats. Chronic inhibition of CaSR selectively increased renal tubular calcium absorption and blood calcium concentration independent of PTH secretion change and without altering intestinal calcium absorption. CaSR inhibition increased blood calcium concentration in animals pretreated with a bisphosphonate, indicating that the increase did not result from release of bone calcium. Kidney CaSR was expressed primarily in the thick ascending limb of the loop of Henle (TAL). As measured by in vitro microperfusion of cortical TAL, CaSR inhibitors increased calcium reabsorption and paracellular pathway permeability but did not change NaCl reabsorption. We conclude that CaSR is a direct determinant of blood calcium concentration, independent of PTH, and modulates renal tubular calcium transport in the TAL via the permeability of the paracellular pathway. These findings suggest that CaSR inhibitors may provide a new specific treatment for disorders related to impaired PTH secretion, such as primary hypoparathyroidism.
Collapse
Affiliation(s)
- Alexandre Loupy
- INSERM UMRS 872, Centre de Recherche des Cordeliers, Paris, France
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
74
|
Breitwieser GE. Minireview: the intimate link between calcium sensing receptor trafficking and signaling: implications for disorders of calcium homeostasis. Mol Endocrinol 2012; 26:1482-95. [PMID: 22745192 DOI: 10.1210/me.2011-1370] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The calcium-sensing receptor (CaSR) regulates organismal Ca(2+) homeostasis. Dysregulation of CaSR expression or mutations in the CASR gene cause disorders of Ca(2+) homeostasis and contribute to the progression or severity of cancers and cardiovascular disease. This brief review highlights recent findings that define the CaSR life cycle, which controls the cellular abundance of CaSR and CaSR signaling. A novel mechanism, termed agonist-driven insertional signaling (ADIS), contributes to the unique hallmarks of CaSR signaling, including the high degree of cooperativity and the lack of functional desensitization. Agonist-mediated activation of plasma membrane-localized CaSR increases the rate of insertion of CaSR at the plasma membrane without altering the constitutive endocytosis rate, thereby acutely increasing the maximum signaling response. Prolonged CaSR signaling requires a large intracellular ADIS-mobilizable pool of CaSR, which is maintained by signaling-mediated increases in biosynthesis. This model provides a rational framework for characterizing the defects caused by CaSR mutations and the altered functional expression of wild-type CaSR in disease states. Mechanistic dissection of ADIS of CaSR should lead to optimized pharmacological approaches to normalize CaSR signaling in disorders of Ca(2+) homeostasis.
Collapse
Affiliation(s)
- Gerda E Breitwieser
- Weis Center for Research, Geisinger Clinic, Danville, Pennsylvania 17822-2604, USA.
| |
Collapse
|
75
|
Smajilovic S, Yano S, Jabbari R, Tfelt-Hansen J. The calcium-sensing receptor and calcimimetics in blood pressure modulation. Br J Pharmacol 2012; 164:884-93. [PMID: 21410453 DOI: 10.1111/j.1476-5381.2011.01317.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Calcium is a crucial second messenger in the cardiovascular system. However, calcium may also be an extracellular first messenger through a G-protein-coupled receptor that senses extracellular concentration (Ca(2+)(o)), the calcium-sensing receptor (CaR). The most prominent physiological function of the CaR is to maintain the extracellular Ca(2+) level in a very tight range by regulating the circulating levels of parathyroid hormone (PTH). This control over PTH and Ca(2+) levels is partially lost in patients suffering from primary and secondary hyperparathyroidism. Allosteric modulators of the CaR (calcimimetics) are the first drugs in their class to become available for clinical use and have been shown to successfully treat certain forms of primary and secondary hyperparathyroidism. In addition, several studies suggest beneficial effects of calcimimetics on cardiovascular risk factors associated with hyperparathyroidism. Although a plethora of studies demonstrated the CaR in heart and blood vessels, exact roles of the receptor in the cardiovascular system still remain to be elucidated. However, several studies point toward a possibility that the CaR might be involved in the regulation of vascular tone. This review will summarize the current knowledge on the possible functions of the CaR and calcimimetics on blood pressure regulation.
Collapse
Affiliation(s)
- Sanela Smajilovic
- Laboratory of Molecular Cardiology, Department of Cardiology, Copenhagen University Hospital, Denmark
| | | | | | | |
Collapse
|
76
|
Procino G, Mastrofrancesco L, Tamma G, Lasorsa DR, Ranieri M, Stringini G, Emma F, Svelto M, Valenti G. Calcium-sensing receptor and aquaporin 2 interplay in hypercalciuria-associated renal concentrating defect in humans. An in vivo and in vitro study. PLoS One 2012; 7:e33145. [PMID: 22403735 PMCID: PMC3293925 DOI: 10.1371/journal.pone.0033145] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Accepted: 02/10/2012] [Indexed: 01/08/2023] Open
Abstract
One mechanism proposed for reducing the risk of calcium renal stones is activation of the calcium-sensing receptor (CaR) on the apical membranes of collecting duct principal cells by high luminal calcium. This would reduce the abundance of aquaporin-2 (AQP2) and in turn the rate of water reabsorption. While evidence in cells and in hypercalciuric animal models supports this hypothesis, the relevance of the interplay between the CaR and AQP2 in humans is not clear. This paper reports for the first time a detailed correlation between urinary AQP2 excretion under acute vasopressin action (DDAVP treatment) in hypercalciuric subjects and in parallel analyzes AQP2-CaR crosstalk in a mouse collecting duct cell line (MCD4) expressing endogenous and functional CaR. In normocalciurics, DDAVP administration resulted in a significant increase in AQP2 excretion paralleled by an increase in urinary osmolality indicating a physiological response to DDAVP. In contrast, in hypercalciurics, baseline AQP2 excretion was high and did not significantly increase after DDAVP. Moreover DDAVP treatment was accompanied by a less pronounced increase in urinary osmolality. These data indicate reduced urinary concentrating ability in response to vasopressin in hypercalciurics. Consistent with these results, biotinylation experiments in MCD4 cells revealed that membrane AQP2 expression in unstimulated cells exposed to CaR agonists was higher than in control cells and did not increase significantly in response to short term exposure to forskolin (FK). Interestingly, we found that CaR activation by specific agonists reduced the increase in cAMP and prevented any reduction in Rho activity in response to FK, two crucial pathways for AQP2 translocation. These data support the hypothesis that CaR–AQP2 interplay represents an internal renal defense to mitigate the effects of hypercalciuria on the risk of calcium precipitation during antidiuresis. This mechanism and possibly reduced medulla tonicity may explain the lower concentrating ability observed in hypercalciuric patients.
Collapse
Affiliation(s)
- Giuseppe Procino
- Department of Biosciences, Biotechnologies and Pharmacological Sciences and Center of Excellence in Comparative Genomics, University of Bari, Bari, Italy
| | - Lisa Mastrofrancesco
- Department of Biosciences, Biotechnologies and Pharmacological Sciences and Center of Excellence in Comparative Genomics, University of Bari, Bari, Italy
| | - Grazia Tamma
- Department of Biosciences, Biotechnologies and Pharmacological Sciences and Center of Excellence in Comparative Genomics, University of Bari, Bari, Italy
| | - Domenica Rita Lasorsa
- Department of Biosciences, Biotechnologies and Pharmacological Sciences and Center of Excellence in Comparative Genomics, University of Bari, Bari, Italy
| | - Marianna Ranieri
- Department of Biosciences, Biotechnologies and Pharmacological Sciences and Center of Excellence in Comparative Genomics, University of Bari, Bari, Italy
| | | | | | - Maria Svelto
- Department of Biosciences, Biotechnologies and Pharmacological Sciences and Center of Excellence in Comparative Genomics, University of Bari, Bari, Italy
| | - Giovanna Valenti
- Department of Biosciences, Biotechnologies and Pharmacological Sciences and Center of Excellence in Comparative Genomics, University of Bari, Bari, Italy
- * E-mail:
| |
Collapse
|
77
|
Bozic M, Valdivielso JM. Calcium signaling in renal tubular cells. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 740:933-44. [PMID: 22453977 DOI: 10.1007/978-94-007-2888-2_42] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The kidney handles calcium by filtration and reabsorption. About 60% of the plasma calcium is filterable, and 99% is reabsorbed in the tubule. In the proximal tubule, the reabsorption is passive and paracellular, but in the distal tubule is active and transcellular. Thus, renal tubular cells are exposed to very high concentrations of calcium in both, the extracellular and the intracellular compartments. Extracellular calcium signaling is transmitted by the calcium sensing receptor, located both in the luminal and basolateral sides of tubular cells. This receptor is able to control levels of extracellular calcium and acts in consequence to maintain calcium homeostasis. Furthermore, renal tubular cells possess several calcium channels that regulate some of the cell functions. Among those, voltage gated calcium channels, transient receptor potential channels and N-methyl-D-aspartate receptor channels have been reported to control several functions. Those functions include survival, apoptosis, differentiation, epithelial-mesenchymal transition, and active vitamin D and renin synthesis.
Collapse
Affiliation(s)
- Milica Bozic
- Nephrology Research Laboratory, IRB Lleida, University Hospital Arnau de Vilanova, Rovira Roure 80, Planta 1, 25198 Lleida, Spain.
| | | |
Collapse
|
78
|
Vezzoli G, Terranegra A, Rainone F, Arcidiacono T, Cozzolino M, Aloia A, Dogliotti E, Cusi D, Soldati L. Calcium-sensing receptor and calcium kidney stones. J Transl Med 2011; 9:201. [PMID: 22107799 PMCID: PMC3339356 DOI: 10.1186/1479-5876-9-201] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Accepted: 11/22/2011] [Indexed: 01/08/2023] Open
Abstract
Calcium nephrolithiasis may be considered as a complex disease having multiple pathogenetic mechanisms and characterized by various clinical manifestations. Both genetic and environmental factors may increase susceptibility to calcium stones; therefore, it is crucial to characterize the patient phenotype to distinguish homogeneous groups of stone formers. Family and twin studies have shown that the stone transmission pattern is not mendelian, but complex and polygenic. In these studies, heritability of calcium stones was calculated around 50% Calcium-sensing receptor (CaSR) is mostly expressed in the parathyroid glands and in renal tubules. It regulates the PTH secretion according to the serum calcium concentration. In the kidney, it modulates electrolyte and water excretion regulating the function of different tubular segments. In particular, CaSR reduces passive and active calcium reabsorption in distal tubules, increases phosphate reabsorption in proximal tubules and stimulates proton and water excretion in collecting ducts. Therefore, it is a candidate gene for calcium nephrolithiasis. In a case-control study we found an association between the normocitraturic stone formers and two SNPs of CaSR, located near the promoters region (rs7652589 and rs1501899). This result was replicated in patients with primary hyperparathyroidism, comparing patients with or without kidney stones. Bioinformatic analysis suggested that the minor alleles at these polymorphisms were able to modify the binding sites of specific transcription factors and, consequently, CaSR expression. Our studies suggest that CaSR is one of the candidate genes explaining individual predisposition to calcium nephrolithiasis. Stone formation may be favored by an altered CaSR expression in kidney medulla involving the normal balance among calcium, phosphate, protons and water excretion.
Collapse
Affiliation(s)
- Giuseppe Vezzoli
- Nephrology and Dialysis Unit, San Raffaele Hospital, Vita Salute University, Milan, Italy
| | | | | | | | | | | | | | | | | |
Collapse
|
79
|
Wagner CA, Mohebbi N, Uhlig U, Giebisch GH, Breton S, Brown D, Geibel JP. Angiotensin II stimulates H⁺-ATPase activity in intercalated cells from isolated mouse connecting tubules and cortical collecting ducts. Cell Physiol Biochem 2011; 28:513-20. [PMID: 22116365 DOI: 10.1159/000335112] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/21/2011] [Indexed: 11/19/2022] Open
Abstract
Intercalated cells in the collecting duct system express V-type H(+)-ATPases which participate in acid extrusion, bicarbonate secretion, and chloride absorption depending on the specific subtype. The activity of H(+)-ATPases is regulated by acid-base status and several hormones, including angiotensin II and aldosterone. Angiotensin II stimulates chloride absorption mediated by pendrin in type B intercalated cells and this process is energized by the activity of H(+)-ATPases. Moreover, angiotensin II stimulates bicarbonate secretion by the connecting tubule (CNT) and early cortical collecting duct (CCD). In the present study we examined the effect of angiotensin II (10 nM) on H(+)-ATPase activity and localization in isolated mouse connecting tubules and cortical collecting ducts. Angiotensin II stimulated Na(+)-independent intracellular pH recovery about 2-3 fold, and this was abolished by the specific H(+)-ATPase inhibitor concanamycin. The effect of angiotensin II was mediated through type 1 angiotensin II receptors (AT(1)-receptors) because it could be blocked by saralasin. Stimulation of H(+)-ATPase activity required an intact microtubular network--it was completely inhibited by colchicine. Immunocytochemistry of isolated CNT/CCDs incubated in vitro with angiotensin II suggests enhanced membrane associated staining of H(+)-ATPases in pendrin expressing intercalated cells. In summary, angiotensin II stimulates H(+)-ATPases in CNT/CCD intercalated cells, and may contribute to the regulation of chloride absorption and bicarbonate secretion in this nephron segment.
Collapse
Affiliation(s)
- Carsten A Wagner
- Department of Cellular and Molecular Physiology, School of Medicine, Yale University, New Haven, CT, USA.
| | | | | | | | | | | | | |
Collapse
|
80
|
Chou YH, Woon PY, Chen WC, Hsu YW, Chang JM, Hwang DY, Chiu YC, Kuo HC, Chang WP, Hou MF, Liu ME, Chang JG, Chang WC. A genetic polymorphism (rs17251221) in the calcium-sensing receptor gene (CASR) is associated with stone multiplicity in calcium nephrolithiasis. PLoS One 2011; 6:e25227. [PMID: 21966463 PMCID: PMC3178627 DOI: 10.1371/journal.pone.0025227] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Accepted: 08/30/2011] [Indexed: 01/28/2023] Open
Abstract
Calcium nephrolithiasis is one of the most common causes of renal stones. While the prevalence of this disease has increased steadily over the last 3 decades, its pathogenesis is still unclear. Previous studies have indicated that a genetic polymorphism (rs17251221) in the calcium-sensing receptor gene (CASR) is associated with the total serum calcium levels. In this study, we collected DNA samples from 480 Taiwanese subjects (189 calcium nephrolithiasis patients and 291 controls) for genotyping the CASR gene. Our results indicated no significant association between the CASR polymorphism (rs17251221) and the susceptibility of calcium nephrolithiasis. However, we found a significant association between rs17251221 and stone multiplicity. The risk of stone multiplicity was higher in patients with the GG+GA genotype than in those with the AA genotype (chi-square test: P = 0.008; odds ratio = 4.79; 95% confidence interval, 1.44-15.92; Yates' correction for chi-square test: P = 0.013). In conclusion, our results provide evidence supporting the genetic effects of CASR on the pathogenesis of calcium nephrolithiasis.
Collapse
Affiliation(s)
- Yii-Her Chou
- Department of Urology, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
- Department of Urology, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan
| | - Peng Yeong Woon
- Department of Molecular Biology and Human Genetics, Tzu Chi University, Hualien, Taiwan
| | - Wei-Chiao Chen
- Department of Medical Genetics, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Yu-Wen Hsu
- Department of Medical Genetics, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Jer-Ming Chang
- Division of Nephrology, Department of Medicine, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan
| | - Daw-Yang Hwang
- Division of Nephrology, Department of Medicine, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan
| | - Yi-Ching Chiu
- Department of Medical Genetics, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Ho-Chang Kuo
- Division of Allergy, Immunology and Rheumatology, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Kaohsiung, Taiwan
- Division of Cardiology, Department of Pediatrics, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Kaohsiung, Taiwan
| | - Wei-Pin Chang
- Department of Healthcare Management, Yuanpei University, HsinChu, Taiwan
| | - Ming-Feng Hou
- Cancer Center, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan
- Department of Surgery, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Mu-En Liu
- Department of Medical Genetics, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Jan-Gowth Chang
- Cancer Center, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan
- Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan
| | - Wei-Chiao Chang
- Department of Medical Genetics, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
- Cancer Center, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan
- Center for Resources, Research and Development, Kaohsiung Medical University, Kaohsiung, Taiwan
| |
Collapse
|
81
|
Pan W, Borovac J, Spicer Z, Hoenderop JG, Bindels RJ, Shull GE, Doschak MR, Cordat E, Alexander RT. The epithelial sodium/proton exchanger, NHE3, is necessary for renal and intestinal calcium (re)absorption. Am J Physiol Renal Physiol 2011; 302:F943-56. [PMID: 21937605 DOI: 10.1152/ajprenal.00504.2010] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Passive paracellular proximal tubular (PT) and intestinal calcium (Ca(2+)) fluxes have been linked to active sodium (re)absorption. Although the epithelial sodium/proton exchanger, NHE3, mediates apical sodium entry at both these sites, its role in Ca(2+) homeostasis remains unclear. We, therefore, set out to determine whether NHE3 is necessary for Ca(2+) (re)absorption from these epithelia by comparing Ca(2+) handling between wild-type and NHE3(-/-) mice. Serum Ca(2+) and plasma parathyroid hormone levels were not different between groups. However, NHE3(-/-) mice had increased serum 1,25-dihydroxyvitamin D(3). The fractional excretion of Ca(2+) was also elevated in NHE3(-/-) mice. Paracellular Ca(2+) flux across confluent monolayers of a PT cell culture model was increased by an osmotic gradient equivalent to that generated by NHE3 across the PT in vivo and by overexpression of NHE3.( 45)Ca(2+) uptake after oral gavage and flux studies in Ussing chambers across duodenum of wild-type and NHE3(-/-) mice confirmed decreased Ca(2+) absorption in NHE3(-/-) mice compared with wild-type mice. Consistent with this, intestinal calbindin-D(9K), claudin-2, and claudin-15 mRNA expression was decreased. Microcomputed tomography analysis revealed a perturbation in bone mineralization. NHE3(-/-) mice had both decreased cortical bone mineral density and trabecular bone mass. Our results demonstrate significant alterations of Ca(2+) homeostasis in NHE3(-/-) mice and provide a molecular link between Na(+) and Ca(2+) (re)absorption.
Collapse
Affiliation(s)
- Wanling Pan
- Division of Nephrology, Department of Pediatrics, University of Alberta, Edmonton, AB, Canada
| | | | | | | | | | | | | | | | | |
Collapse
|
82
|
Bushinsky DA, Willett T, Asplin JR, Culbertson C, Che SPY, Grynpas M. Chlorthalidone improves vertebral bone quality in genetic hypercalciuric stone-forming rats. J Bone Miner Res 2011; 26:1904-12. [PMID: 21351146 PMCID: PMC4493760 DOI: 10.1002/jbmr.374] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
We have bred a strain of rats to maximize urine (u) calcium (Ca) excretion and model hypercalciuric nephrolithiasis. These genetic hypercalciuric stone-forming (GHS) rats excrete more uCa than control Sprague-Dawley rats, uniformly form kidney stones, and similar to patients, demonstrate lower bone mineral density. Clinically, thiazide diuretics reduce uCa and prevent stone formation; however, whether they benefit bone is not clear. We used GHS rats to test the hypothesis that the thiazide diuretic chlorthalidone (CTD) would have a favorable effect on bone density and quality. Twenty GHS rats received a fixed amount of a 1.2% Ca diet, and half also were fed CTD (4 to 5 mg/kg/d). Rats fed CTD had a marked reduction in uCa. The axial and appendicular skeletons were studied. An increase in trabecular mineralization was observed with CTD compared with controls. CTD also improved the architecture of trabecular bone. Using micro-computed tomography (µCT), trabecular bone volume (BV/TV), trabecular thickness, and trabecular number were increased with CTD. A significant increase in trabecular thickness with CTD was confirmed by static histomorphometry. CTD also improved the connectivity of trabecular bone. Significant improvements in vertebral strength and stiffness were measured by vertebral compression. Conversely, a slight loss of bending strength was detected in the femoral diaphysis with CTD. Thus results obtained in hypercalciuric rats suggest that CTD can favorably influence vertebral fracture risk. CTD did not alter formation parameters, suggesting that the improved vertebral bone strength was due to decreased bone resorption and retention of bone structure.
Collapse
Affiliation(s)
- David A Bushinsky
- Nephrology Division, Department of Medicine, University of Rochester School of Medicine, Rochester, NY 14642, USA.
| | | | | | | | | | | |
Collapse
|
83
|
Renkema KY, Bindels RJM, Hoenderop JGJ. Role of the calcium-sensing receptor in reducing the risk for calcium stones. Clin J Am Soc Nephrol 2011; 6:2076-82. [PMID: 21784822 DOI: 10.2215/cjn.00480111] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The tight control of blood Ca2+ levels within a narrow range is essential for the performance of vital physiologic functions. Muscle contraction, neuronal excitation, and intracellular signaling processes acquisitively require Ca2+. It is the concerted action of intestine, bone, and kidney that controls the Ca2+ balance through the regulation of intestinal absorption, bone (de)mineralization, and renal excretion of Ca2+, respectively. Along the nephron, fine-tuning of blood Ca2+ levels takes place by Ca2+ reabsorption. The calciotropic hormones regulate Ca2+ transport processes, leading to whole-body Ca2+ homeostasis and, importantly, preserving a constant Ca2+ concentration in the blood. Defects in renal Ca2+ handling can lead to hypercalciuria, consecutive kidney stone formation, and obstructive nephropathy. Here we give an overview of the key players involved in normal Ca2+ management and describe the in-depth investigations on a renal hypercalciuric model of disease, the Trpv5 knockout mouse, which naturally displays molecular adaptations that prevent Ca2+ precipitation in the kidney.
Collapse
Affiliation(s)
- Kirsten Y Renkema
- Department of Physiology (286), Radboud University Nijmegen Medical Centre (RUNMC), P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
| | | | | |
Collapse
|
84
|
Fenton RA, Praetorius J. Molecular Physiology of the Medullary Collecting Duct. Compr Physiol 2011; 1:1031-56. [DOI: 10.1002/cphy.c100064] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
85
|
Peng JB. TRPV5 and TRPV6 in transcellular Ca(2+) transport: regulation, gene duplication, and polymorphisms in African populations. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011; 704:239-75. [PMID: 21290300 DOI: 10.1007/978-94-007-0265-3_14] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
TRPV5 and TRPV6 are unique members of the TRP super family. They are highly selective for Ca(2+) ions with multiple layers of Ca(2+)-dependent inactivation mechanisms, expressed at the apical membrane of Ca(2+) transporting epithelia, and robustly responsive to 1,25-dihydroxivitamin D(3). These features are well suited for their roles as Ca(2+) entry channels in the first step of transcellular Ca(2+) transport pathways, which are involved in intestinal absorption, renal reabsorption of Ca(2+), placental transfer of Ca(2+) to fetus, and many other processes. While TRPV6 is more broadly expressed in a variety of tissues such as esophagus, stomach, small intestine, colon, kidney, placenta, pancreas, prostate, uterus, salivary gland, and sweat gland, TRPV5 expression is relatively restricted to the distal convoluted tubule and connecting tubule of the kidney. There is only one TRPV6-like gene in fish and birds in comparison to both TRPV5 and TRPV6 genes in mammals, indicating TRPV5 gene was likely generated from duplication of TRPV6 gene during the evolution of mammals to meet the needs of complex renal function. TRPV5 and TRPV6 are subjected to vigorous regulations under physiological, pathological, and therapeutic conditions. The elevated TRPV6 level in malignant tumors such as prostate and breast cancers makes it a potential therapeutic target. TRPV6, and to a lesser extent TRPV5, exhibit unusually high levels of single nucleotide polymorphisms (SNPs) in African populations as compared to other populations, indicating TRPV6 gene was under selective pressure during or after humans migrated out of Africa. The SNPs of TRPV6 and TRPV5 likely contribute to the Ca(2+) conservation mechanisms in African populations.
Collapse
Affiliation(s)
- Ji-Bin Peng
- Division of Nephrology, Department of Medicine, Nephrology Research and Training Center, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
| |
Collapse
|
86
|
Elizondo MR, Budi EH, Parichy DM. trpm7 regulation of in vivo cation homeostasis and kidney function involves stanniocalcin 1 and fgf23. Endocrinology 2010; 151:5700-9. [PMID: 20881241 PMCID: PMC2999483 DOI: 10.1210/en.2010-0853] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2010] [Accepted: 08/25/2010] [Indexed: 12/31/2022]
Abstract
The transient receptor potential melastatin 7 (trpm7) channel kinase is a primary regulator of magnesium homeostasis in vitro. Here we show that trpm7 is an important regulator of cation homeostasis as well as kidney function in vivo. Using zebrafish trpm7 mutants, we show that early larvae exhibit reduced levels of both total magnesium and total calcium. Accompanying these deficits, we show that trpm7 mutants express higher levels of stanniocalcin 1 (stc1), a potent regulator of calcium homeostasis. Using transgenic overexpression and morpholino oligonucleotide knockdown, we demonstrate that stc1 modulates both calcium and magnesium levels in trpm7 mutants and in the wild type and that levels of these cations are restored to normal in trpm7 mutants when stc1 activity is blocked. Consistent with defects in both calcium and phosphate homeostasis, we further show that trpm7 mutants develop kidney stones by early larval stages and exhibit increased levels of the anti-hyperphosphatemic factor, fibroblast growth factor 23 (fgf23). Finally, we demonstrate that elevated fgf23 expression contributes to kidney stone formation by morpholino knockdown of fgf23 in trpm7 mutants. Together, these analyses reveal roles for trpm7 in regulating cation homeostasis and kidney function in vivo and implicate both stc1 and fgf23 in these processes.
Collapse
Affiliation(s)
- Michael R Elizondo
- Department of Biology, University of Washington, Seattle, Washington 98195, USA
| | | | | |
Collapse
|
87
|
Markadieu N, Bindels RJ, Hoenderop JG. The renal connecting tubule: Resolved and unresolved issues in Ca(2+) transport. Int J Biochem Cell Biol 2010; 43:1-4. [PMID: 20969972 DOI: 10.1016/j.biocel.2010.10.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Revised: 10/07/2010] [Accepted: 10/14/2010] [Indexed: 10/18/2022]
Abstract
The renal connecting tubule (CNT) localizes to the distal part of the nephron between the distal convoluted tubule and the collecting duct, and consists of two different cell types: segment-specific and intercalated cells. The former reabsorb water (H(2)O), sodium (Na(+)) and calcium (Ca(2+)) ions to the blood compartment, while secreting potassium ions (K(+)) into the pro-urine. The latter cells contribute to the renal control of the acid-base balance. Several factors and hormones tightly regulate these transport processes. Although the CNT reabsorbs only ∼15% of filtered Ca(2+) load, this segment is finally decisive for the amount of Ca(2+) that appears in the urine. Impaired Ca(2+) transport across CNT can provoke severe urinary Ca(2+) excretion, called hypercalciuria. This review mainly focuses on the activity, abundance and expression of the epithelial Ca(2+) channel named Transient Receptor Potential Vanilloid 5 (TRPV5) that is the gatekeeper of active Ca(2+) reabsorption in the CNT.
Collapse
Affiliation(s)
- Nicolas Markadieu
- Department of Physiology, Radboud University Nijmegen Medical Centre, The Netherlands
| | | | | |
Collapse
|
88
|
Ormazabal V, Zuñiga FA, Escobar E, Aylwin C, Salas-Burgos A, Godoy A, Reyes AM, Vera JC, Rivas CI. Histidine residues in the Na+-coupled ascorbic acid transporter-2 (SVCT2) are central regulators of SVCT2 function, modulating pH sensitivity, transporter kinetics, Na+ cooperativity, conformational stability, and subcellular localization. J Biol Chem 2010; 285:36471-85. [PMID: 20843809 DOI: 10.1074/jbc.m110.155630] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Na(+)-coupled ascorbic acid transporter-2 (SVCT2) activity is impaired at acid pH, but little is known about the molecular determinants that define the transporter pH sensitivity. SVCT2 contains six histidine residues in its primary sequence, three of which are exofacial in the transporter secondary structure model. We used site-directed mutagenesis and treatment with diethylpyrocarbonate to identify histidine residues responsible for SVCT2 pH sensitivity. We conclude that five histidine residues, His(109), His(203), His(206), His(269), and His(413), are central regulators of SVCT2 function, participating to different degrees in modulating pH sensitivity, transporter kinetics, Na(+) cooperativity, conformational stability, and subcellular localization. Our results are compatible with a model in which (i) a single exofacial histidine residue, His(413), localized in the exofacial loop IV that connects transmembrane helices VII-VIII defines the pH sensitivity of SVCT2 through a mechanism involving a marked attenuation of the activation by Na(+) and loss of Na(+) cooperativity, which leads to a decreased V(max) without altering the transport K(m); (ii) exofacial histidine residues His(203), His(206), and His(413) may be involved in maintaining a functional interaction between exofacial loops II and IV and influence the general folding of the transporter; (iii) histidines 203, 206, 269, and 413 affect the transporter kinetics by modulating the apparent transport K(m); and (iv) histidine 109, localized at the center of transmembrane helix I, might be fundamental for the interaction of SVCT2 with the transported substrate ascorbic acid. Thus, histidine residues are central regulators of SVCT2 function.
Collapse
Affiliation(s)
- Valeska Ormazabal
- Departamento de Fisiopatología, Facultad de Ciencias Biológicas, Universidad de Concepción, Barrio Universitario, Casilla 160C, Concepción, Chile
| | | | | | | | | | | | | | | | | |
Collapse
|
89
|
Vervaet BA, Verhulst A, De Broe ME, D'Haese PC. The tubular epithelium in the initiation and course of intratubular nephrocalcinosis. ACTA ACUST UNITED AC 2010; 38:249-56. [PMID: 20680256 DOI: 10.1007/s00240-010-0290-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2010] [Accepted: 06/24/2010] [Indexed: 01/05/2023]
Abstract
Intratubular nephrocalcinosis is defined as the histological observation of calcium oxalate and/or calcium phosphate deposits retained within the lumen of the renal tubules. As the tubular epithelium is the primary interaction partner of crystals formed in the tubular fluid, the role of the epithelial cells in nephrocalcinosis has been investigated intensively. This review summarizes our current understanding on how the tubular epithelium mechanistically appears to be involved both in the initiation and in the course of nephrocalcinosis, with emphasis on in vivo observations.
Collapse
Affiliation(s)
- Benjamin A Vervaet
- Laboratory of Pathophysiology, University of Antwerp, Campus Drie Eiken, Universiteitsplein 1, 2610 Antwerp, Belgium.
| | | | | | | |
Collapse
|
90
|
Bindels RJ. 2009 Homer W. Smith Award: Minerals in Motion: From New Ion Transporters to New Concepts. J Am Soc Nephrol 2010; 21:1263-9. [DOI: 10.1681/asn.2010010001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
|
91
|
Bernascone I, Janas S, Ikehata M, Trudu M, Corbelli A, Schaeffer C, Rastaldi MP, Devuyst O, Rampoldi L. A transgenic mouse model for uromodulin-associated kidney diseases shows specific tubulo-interstitial damage, urinary concentrating defect and renal failure. Hum Mol Genet 2010; 19:2998-3010. [PMID: 20472742 DOI: 10.1093/hmg/ddq205] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Uromodulin-associated kidney diseases (UAKD) are autosomal-dominant disorders characterized by alteration of urinary concentrating ability, tubulo-interstitial fibrosis, hyperuricaemia and renal cysts at the cortico-medullary junction. UAKD are caused by mutations in UMOD, the gene encoding uromodulin. Although uromodulin is the most abundant protein secreted in urine, its physiological role remains elusive. Several in vitro studies demonstrated that mutations in uromodulin lead to endoplasmic reticulum (ER) retention of mutant protein, but their relevance in vivo has not been studied. We here report on the generation and characterization of the first transgenic mouse model for UAKD. Transgenic mice that express the C147W mutant uromodulin (Tg(Umod)(C147W)), corresponding to the well-established patient mutation C148W, were compared with expression-matched transgenic mice expressing the wild-type protein (Tg(Umod)(wt)). Tg(Umod)(C147W) mice recapitulate most of the UAKD features, with urinary concentrating defect of renal origin and progressive renal injury, i.e. tubulo-interstitial fibrosis with inflammatory cell infiltration, tubule dilation and specific damage of the thick ascending limb of Henle's loop, leading to mild renal failure. As observed in patients, Tg(Umod)(C147W) mice show a marked reduction of urinary uromodulin excretion. Mutant uromodulin trafficking to the plasma membrane is indeed impaired as it is retained in the ER of expressing cells leading to ER hyperplasia. The Tg(Umod)(C147W) mice represent a unique model that recapitulates most of the features associated with UAKD. Our data clearly demonstrate a gain-of-toxic function of uromodulin mutations providing insights into the pathogenetic mechanism of the disease. These findings may also be relevant for other tubulo-interstitial or ER-storage disorders.
Collapse
Affiliation(s)
- Ilenia Bernascone
- Division of Genetics and Cell Biology, Dulbecco Telethon Institute, Milan, Italy
| | | | | | | | | | | | | | | | | |
Collapse
|
92
|
Abstract
We recommend changing the name of the milk-alkali syndrome to the calcium-alkali syndrome, because the new terminology better reflects the shifting epidemiology and understanding of this disorder. The calcium-alkali syndrome is now the third most common cause of hospital admission for hypercalcemia, and those at greatest risk are postmenopausal or pregnant women. The incidence of the calcium-alkali syndrome is growing in large part as a result of the widespread use of over-the-counter calcium and vitamin D supplements. Advertising for treatment or prevention of osteoporosis has long encouraged this use. Intricate mechanisms mediating the calcium-alkali syndrome depend on interplay among intestine, kidney, and bone. New insights regarding its pathogenesis focus on the key role of calcium-sensing receptors and TRPV5 channels in the modulation of renal calcium excretion. Restoring extracellular blood volume, increasing GFR and calcium excretion, and discontinuing calcium supplementation provide best treatment.
Collapse
Affiliation(s)
- Ami M Patel
- Renal-Electrolyte and Hypertension Division, Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
| | | |
Collapse
|
93
|
Riccardi D, Brown EM. Physiology and pathophysiology of the calcium-sensing receptor in the kidney. Am J Physiol Renal Physiol 2010; 298:F485-99. [PMID: 19923405 PMCID: PMC2838589 DOI: 10.1152/ajprenal.00608.2009] [Citation(s) in RCA: 264] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2009] [Accepted: 11/13/2009] [Indexed: 12/21/2022] Open
Abstract
The extracellular calcium-sensing receptor (CaSR) plays a major role in the maintenance of a physiological serum ionized calcium (Ca2+) concentration by regulating the circulating levels of parathyroid hormone. It was molecularly identified in 1993 by Brown et al. in the laboratory of Dr. Steven Hebert with an expression cloning strategy. Subsequent studies have demonstrated that the CaSR is highly expressed in the kidney, where it is capable of integrating signals deriving from the tubular fluid and/or the interstitial plasma. Additional studies elucidating inherited and acquired mutations in the CaSR gene, the existence of activating and inactivating autoantibodies, and genetic polymorphisms of the CaSR have greatly enhanced our understanding of the role of the CaSR in mineral ion metabolism. Allosteric modulators of the CaSR are the first drugs in their class to become available for clinical use and have been shown to treat successfully hyperparathyroidism secondary to advanced renal failure. In addition, preclinical and clinical studies suggest the possibility of using such compounds in various forms of hypercalcemic hyperparathyroidism, such as primary and lithium-induced hyperparathyroidism and that occurring after renal transplantation. This review addresses the role of the CaSR in kidney physiology and pathophysiology as well as current and in-the-pipeline treatments utilizing CaSR-based therapeutics.
Collapse
Affiliation(s)
- Daniela Riccardi
- School of Biosciences, Cardiff University, Cardiff, United Kingdom.
| | | |
Collapse
|
94
|
Will C, Breiderhoff T, Thumfart J, Stuiver M, Kopplin K, Sommer K, Günzel D, Querfeld U, Meij IC, Shan Q, Bleich M, Willnow TE, Müller D. Targeted deletion of murine Cldn16 identifies extra- and intrarenal compensatory mechanisms of Ca2+ and Mg2+ wasting. Am J Physiol Renal Physiol 2010; 298:F1152-61. [PMID: 20147368 DOI: 10.1152/ajprenal.00499.2009] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Claudin-16 (CLDN16) is critical for renal paracellular epithelial transport of Ca(2+) and Mg(2+) in the thick ascending loop of Henle. To gain novel insights into the role of CLDN16 in renal Ca(2+) and Mg(2+) homeostasis and the pathological mechanisms underlying a human disease associated with CLDN16 dysfunction [familial hypomagnesemia with hypercalciuria and nephrocalcinosis (FHHNC), OMIM 248250], we generated a mouse model of CLDN16 deficiency. Similar to patients, CLDN16-deficient mice displayed hypercalciuria and hypomagnesemia. Contrary to FHHNC patients, nephrocalcinosis was absent in our model, indicating the existence of compensatory pathways in ion handling in this model. In line with the renal loss of Ca(2+), compensatory mechanisms like parathyroid hormone and 1,25(OH)(2)D(3) were significantly elevated. Also, gene expression profiling revealed transcriptional upregulation of several Ca(2+) and Mg(2+) transport systems including Trpv5, Trpm6, and calbindin-D9k. Induced gene expression was also seen for the transcripts of two putative Mg(2+) transport proteins, Cnnm2 and Atp13a4. Moreover, urinary pH was significantly lower when compared with wild-type mice. Taken together, our findings demonstrate that loss of CLDN16 activity leads to specific alterations in Ca(2+) and Mg(2+) homeostasis and that CLDN16-deficient mice represent a useful model to further elucidate pathways involved in renal Ca(2+) and Mg(2+) handling.
Collapse
Affiliation(s)
- Constanze Will
- Dept. of Pediatric Nephrology, Charité, CVK, Augustenburger Platz 1, 13353 Berlin, Germany
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
95
|
Vezzoli G, Terranegra A, Arcidiacono T, Gambaro G, Milanesi L, Mosca E, Soldati L. Calcium kidney stones are associated with a haplotype of the calcium-sensing receptor gene regulatory region. Nephrol Dial Transplant 2010; 25:2245-52. [DOI: 10.1093/ndt/gfp760] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
|
96
|
Novel Ca receptor signaling pathways for control of renal ion transport. Curr Opin Nephrol Hypertens 2010; 19:106-12. [DOI: 10.1097/mnh.0b013e328332e7b2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
97
|
Nowik M, Kampik NB, Mihailova M, Eladari D, Wagner CA. Induction of Metabolic Acidosis with Ammonium Chloride (NH 4Cl) in Mice and Rats – Species Differences and Technical Considerations. Cell Physiol Biochem 2010; 26:1059-72. [DOI: 10.1159/000323984] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/04/2010] [Indexed: 11/19/2022] Open
|
98
|
Schwille PO, Schmiedl A, Wipplinger J. Idiopathic recurrent calcium urolithiasis (IRCU): variation of fasting urinary protein is a window to pathophysiology or simple consequence of renal stones in situ? A tripartite study in male patients providing insight into oxidative metabolism as possible driving force towards alteration of urine composition, calcium salt crystallization and stone formation. Eur J Med Res 2009; 14:378-92. [PMID: 19748857 PMCID: PMC3351970 DOI: 10.1186/2047-783x-14-9-378] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Background In IRCU it is uncertain whether variation of urinary protein, especially non-albumin protein (NAlb-P), is due to the presence of stones or reflects alteration of oxidative metabolism. Aims To validate in a tripartite cross-sectional study of 187 ambulatory male patients, undergoing a standardized laboratory programme, whether stones impact on N-Alb-P or the state of oxidative metabolism interferes with IRCU pathophysiology. Methods In part 1 the strata low and high of fasting urinary excretion rate per 2 h of N-Alb-P, malonedialdehyde, hypoxanthine, xanthine, pH and other urine components were compared, and association with renal stones in situ evaluated; in part 2 the co-variation of oxidatively modulated environment, fasting urinary pH, calcium (Ca) salt crystallization risk and the number of patients with stones in situ was examined; in part 3, the nucleation of Ca oxalate and Ca phosphate was tested in undiluted postprandial urine of patients and related to the state of oxidative metabolism. Results In part 1, N-Alb-P excretion > 4.3 mg was associated with increase of blood pressure, excretion of total protein, hypoxanthine (a marker of tissue hypoxia), malonedialdehyde (a marker of lipid peroxidation), sodium, magnesium, citrate, uric acid, volume, pH, and increase of renal fractional excretion of both NAlb-P and uric acid; when stones were present, urinary pH was elevated but other parameters were unaffected. Significant predictors of N-Alb-P excretion were malonedialdehyde, fractional N-Alb-P and hypoxanthine. In part 2, urine pH > 6.14 was associated with unchanged blood pressure and plasma vasopressin, increase of blood pH, urinary volume, malonedialde hyde, fractional excretion of N-Alb-P, uric acid, Ca phosphate, but not Ca oxalate, supersaturation; this spectrum was accompanied by decrease of concentration of urinary total and free magnesium, total and complexed citrate, plasma uric acid (in humans the major circulating antioxidant) and insulin; the number of stone-bearing patients was increased. Significant predictors of urine pH were body mass index, plasma insulin and uric acid (negative), and urinary xanthine (positive). In part 3 low plasma uric acid, not high urinary malonedialdehyde or high ratio malonedialdehyde/uric acid was significantly associated with diminished Ca but not oxalate tolerance, with the first nucleating crystal type being mostly Ca phosphate (hydroxyapatite), in the rest Ca oxalate dihydrate; uricemia correlated marginally positively (p = 0.055) with Ca tolerance of urine, stronger with blood pressure and insulin, and negatively with urinary xanthine, fractional N-Alb-P, volume, sodium. Conclusions In IRCU 1) not renal stones in situ, but disturbed oxidative metabolism apparently modulates nephron functionality, ending up in higher renal NAlb-P release, urinary volume, sodium and pH of fasting urine; 2) etiologically unknown decline of uricemia may represent antioxidant deficiency and cause a risk of hydroxyapatite crystallization and stone formation in a weakly acidic or alkaline inhibitor-deficient and NAlb-P-rich milieu; 3) several observations, linking oxidative and systemic metabolism, are compatible with Ca stone initiation beyond tubules.
Collapse
Affiliation(s)
- Paul O Schwille
- Mineral Metabolism and Endocrine Research Laboratory, Departments of Surgery and Urology, University of Erlangen-Nürnberg, Germany.
| | | | | |
Collapse
|
99
|
Journal Club. Kidney Int 2009. [DOI: 10.1038/ki.2009.379] [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]
|
100
|
Worcester EM, Coe FL. Does Idiopathic Hypercalciuria Trigger Calcium-Sensing Receptor–Mediated Protection from Urinary Supersaturation? J Am Soc Nephrol 2009; 20:1657-9. [DOI: 10.1681/asn.2009060580] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
|