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Darisipudi MN, Knauf F. An update on the role of the inflammasomes in the pathogenesis of kidney diseases. Pediatr Nephrol 2016; 31:535-44. [PMID: 26178650 DOI: 10.1007/s00467-015-3153-z] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Revised: 06/15/2015] [Accepted: 06/18/2015] [Indexed: 12/23/2022]
Abstract
Innate immune response pathways play a critical role as the first line of defense. Initiation of an immune response requires sensors that can detect noxious stimuli within the cellular microenvironment. Inflammasomes are signaling platforms that are assembled in response to both microbe-specific and nonmicrobial antigens. Upon activation, proinflammatory cytokines are released to engage immune defenses and to trigger an inflammatory cell death referred to as pyroptosis. The aim of this review is to provide an overview of the current knowledge of the role of the inflammasomes in the pathogenesis of kidney diseases. As crystal deposition in the kidney is a frequent cause of acute kidney injury and chronic kidney disease in children, recent insights into mechanisms of inflammasome activation by renal crystals are highlighted. This may be of particular interest to pediatric patients and nephrologists in need of new therapeutic approaches. Lastly, current data findings that inflammasomes are not only of major importance in host defense but are also a key regulator of the intestinal microbiota and the progression of systemic diseases are reviewed.
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Affiliation(s)
- Murthy N Darisipudi
- Department of Nephrology and Hypertension, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Schwabachanlage 12, 91054, Erlangen, Germany
| | - Felix Knauf
- Department of Nephrology and Hypertension, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Schwabachanlage 12, 91054, Erlangen, Germany. .,Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, USA.
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102
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Reddy TG, Knight J, Holmes RP, Harvey LM, Mitchem ALE, Wilcox CM, Monkemuller KE, Assimos DG. Oxalate Concentrations in Human Gastrointestinal Fluid. J Endourol 2016; 30 Suppl 1:S8-11. [PMID: 26943671 DOI: 10.1089/end.2015.0838] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND AND PURPOSE Urinary oxalate excretion is a risk factor for nephrolithiasis and is a result of endogenous metabolism and gastrointestinal processes. Gastrointestinal absorption of oxalate has been well demonstrated but to our knowledge evidence for secretion of oxalate is absent in humans. The objective of this study was to measure the amount and conformation of oxalate in the stomach and small intestine of adult subjects undergoing gastrointestinal endoscopy. MATERIALS AND METHODS Eleven adults participated in this study. Gastrointestinal fluid was collected from the stomach and small intestine during endoscopy. A determination of the soluble and insoluble components of oxalate was made by centrifugation of the sample and subsequent acidification of the resultant pellet and supernatant. Samples were processed and the amount of oxalate was measured by ion chromatography, the limit of which is 1.6 μM. RESULTS The majority of small intestinal samples contained some degree of oxalate. This is in contrast to the stomach where minimal oxalate was detected. There was a wide range of oxalate concentrations and a greater degree of insoluble oxalate in small intestinal samples. CONCLUSIONS Our results suggest that some degree of oxalate secretion in the small intestine may occur in the fasted state while this is less likely in the stomach. Further studies are warranted to provide definitive evidence of gastrointestinal secretion of oxalate.
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Affiliation(s)
- Thanmaya G Reddy
- 1 Department of Urology, University of Alabama at Birmingham School of Medicine , Birmingham, Alabama
| | - John Knight
- 1 Department of Urology, University of Alabama at Birmingham School of Medicine , Birmingham, Alabama
| | - Ross P Holmes
- 1 Department of Urology, University of Alabama at Birmingham School of Medicine , Birmingham, Alabama
| | - Lisa M Harvey
- 1 Department of Urology, University of Alabama at Birmingham School of Medicine , Birmingham, Alabama
| | - April L E Mitchem
- 1 Department of Urology, University of Alabama at Birmingham School of Medicine , Birmingham, Alabama
| | - Charles M Wilcox
- 2 Division of Gastroenterology and Hepatology, University of Alabama at Birmingham School of Medicine , Birmingham, Alabama
| | - Klaus E Monkemuller
- 2 Division of Gastroenterology and Hepatology, University of Alabama at Birmingham School of Medicine , Birmingham, Alabama
| | - Dean G Assimos
- 1 Department of Urology, University of Alabama at Birmingham School of Medicine , Birmingham, Alabama
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103
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Breljak D, Brzica H, Vrhovac I, Micek V, Karaica D, Ljubojević M, Sekovanić A, Jurasović J, Rašić D, Peraica M, Lovrić M, Schnedler N, Henjakovic M, Wegner W, Burckhardt G, Burckhardt BC, Sabolić I. In female rats, ethylene glycol treatment elevates protein expression of hepatic and renal oxalate transporter sat-1 (Slc26a1) without inducing hyperoxaluria. Croat Med J 2016; 56:447-59. [PMID: 26526882 PMCID: PMC4655930 DOI: 10.3325/cmj.2015.56.447] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Aim To investigate whether the sex-dependent expression of hepatic and renal oxalate transporter sat-1 (Slc26a1) changes in a rat model of ethylene glycol (EG)-induced hyperoxaluria. Methods Rats were given tap water (12 males and 12 females; controls) or EG (12 males and 12 females; 0.75% v/v in tap water) for one month. Oxaluric state was confirmed by biochemical parameters in blood plasma, urine, and tissues. Expression of sat-1 and rate-limiting enzymes of oxalate synthesis, alcohol dehydrogenase 1 (Adh1) and hydroxy-acid oxidase 1 (Hao1), was determined by immunocytochemistry (protein) and/or real time reverse transcription polymerase chain reaction (mRNA). Results EG-treated males had significantly higher (in μmol/L; mean ± standard deviation) plasma (59.7 ± 27.2 vs 12.9 ± 4.1, P < 0.001) and urine (3716 ± 1726 vs 241 ± 204, P < 0.001) oxalate levels, and more abundant oxalate crystaluria than controls, while the liver and kidney sat-1 protein and mRNA expression did not differ significantly between these groups. EG-treated females, in comparison with controls had significantly higher (in μmol/L) serum oxalate levels (18.8 ± 2.9 vs 11.6 ± 4.9, P < 0.001), unchanged urine oxalate levels, low oxalate crystaluria, and significantly higher expression (in relative fluorescence units) of the liver (1.59 ± 0.61 vs 0.56 ± 0.39, P = 0.006) and kidney (1.77 ± 0.42 vs 0.69 ± 0.27, P < 0.001) sat-1 protein, but not mRNA. The mRNA expression of Adh1 was female-dominant and that of Hao1 male-dominant, but both were unaffected by EG treatment. Conclusions An increased expression of hepatic and renal oxalate transporting protein sat-1 in EG-treated female rats could protect from hyperoxaluria and oxalate urolithiasis.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Ivan Sabolić
- Ivan Sabolić, Molecular Toxicology, Institute for Medical Research and Occupational Health, Ksaverska cesta 2, 10000 Zagreb, Croatia,
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104
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Lu X, Sun D, Xu B, Pan J, Wei Y, Mao X, Yu D, Liu H, Gao B. In Silico Screening and Molecular Dynamic Study of Nonsynonymous Single Nucleotide Polymorphisms Associated with Kidney Stones in the SLC26A6 Gene. J Urol 2016; 196:118-23. [PMID: 26812303 DOI: 10.1016/j.juro.2016.01.093] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/14/2016] [Indexed: 10/22/2022]
Abstract
PURPOSE SLC26A6 is a multifunctional anion transporter with a critical physiological role in the transport of oxalate anions. Recognizing a genetic variant of SLC26A6 would advance our understanding of oxalate transport in the formation of calcium oxalate stones. MATERIALS AND METHODS All nsSNPs (nonsynonymous single nucleotide polymorphisms) reported in human SLC26A6 were investigated using 4 in silico tools, including SIFT (Sorting Intolerant From Tolerant), PROVEAN (Protein Variation Effect Analyzer), PhD-SNP (Predictor of human Deleterious Single Nucleotide Polymorphisms) and MutPred. A total of 426 subjects, including 225 with kidney stones and 201 healthy controls, were included in study to genotype the candidate disease associated nsSNP using allele specific polymerase chain reaction. Furthermore, the structural consequences due to the mutation were assessed using homology modeling and molecular dynamics simulation methods. RESULTS The nsSNP rs184187143 was identified as a more probable disease associated variant in the SLC26A6 gene by in silico screening. The C allele carrier showed a 6.1-fold increased kidney stone risk compared with G allele carriers in the nsSNP (OR 6.1, 95% CI 1.36-27.38, p = 0.007). We found that the mutation from arginine to glycine leads to the loss of 2 hydrogen bonds and to an unstable structure in the STAS domain of SLC26A6. CONCLUSIONS Our results indicate that the variant G539R in the SLC26A6 gene is associated with kidney stone risk, providing a clear clue to further achieve insight into oxalate transport in kidney stone formation.
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Affiliation(s)
- Xiuli Lu
- Department of Biochemistry and Cell Biology, School of Life Science, Liaoning University, Shenyang, People's Republic of China; Research Center for Computer Simulating and Information Processing of Bio-macromolecules of Liaoning Province, Shenyang, People's Republic of China
| | - Deliang Sun
- Department of Biochemistry and Cell Biology, School of Life Science, Liaoning University, Shenyang, People's Republic of China
| | - Bo Xu
- Department of Biochemistry and Cell Biology, School of Life Science, Liaoning University, Shenyang, People's Republic of China
| | - Jichuan Pan
- Department of Cell Biology and Genetics, Shenyang Medical College, Shenyang, People's Republic of China
| | - Yanhong Wei
- Department of Cell Biology and Genetics, Shenyang Medical College, Shenyang, People's Republic of China
| | - Xu Mao
- Department of Cell Biology and Genetics, Shenyang Medical College, Shenyang, People's Republic of China
| | - Daojun Yu
- Department of Cell Biology and Genetics, Shenyang Medical College, Shenyang, People's Republic of China
| | - Hongsheng Liu
- Research Center for Computer Simulating and Information Processing of Bio-macromolecules of Liaoning Province, Shenyang, People's Republic of China
| | - Bing Gao
- Department of Cell Biology and Genetics, Shenyang Medical College, Shenyang, People's Republic of China; Key Laboratory of Environment and Population Health of Liaoning Education Ministry, Shenyang Medical College, Shenyang, People's Republic of China; China-Japan Kidney Stone Research Center, Shenyang, People's Republic of China.
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105
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Yin K, Lei Y, Wen X, Lacruz RS, Soleimani M, Kurtz I, Snead ML, White SN, Paine ML. SLC26A Gene Family Participate in pH Regulation during Enamel Maturation. PLoS One 2015; 10:e0144703. [PMID: 26671068 PMCID: PMC4679777 DOI: 10.1371/journal.pone.0144703] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 11/23/2015] [Indexed: 12/15/2022] Open
Abstract
The bicarbonate transport activities of Slc26a1, Slc26a6 and Slc26a7 are essential to physiological processes in multiple organs. Although mutations of Slc26a1, Slc26a6 and Slc26a7 have not been linked to any human diseases, disruption of Slc26a1, Slc26a6 or Slc26a7 expression in animals causes severe dysregulation of acid-base balance and disorder of anion homeostasis. Amelogenesis, especially the enamel formation during maturation stage, requires complex pH regulation mechanisms based on ion transport. The disruption of stage-specific ion transporters frequently results in enamel pathosis in animals. Here we present evidence that Slc26a1, Slc26a6 and Slc26a7 are highly expressed in rodent incisor ameloblasts during maturation-stage tooth development. In maturation-stage ameloblasts, Slc26a1, Slc26a6 and Slc26a7 show a similar cellular distribution as the cystic fibrosis transmembrane conductance regulator (Cftr) to the apical region of cytoplasmic membrane, and the distribution of Slc26a7 is also seen in the cytoplasmic/subapical region, presumably on the lysosomal membrane. We have also examined Slc26a1 and Slc26a7 null mice, and although no overt abnormal enamel phenotypes were observed in Slc26a1-/- or Slc26a7-/- animals, absence of Slc26a1 or Slc26a7 results in up-regulation of Cftr, Ca2, Slc4a4, Slc4a9 and Slc26a9, all of which are involved in pH homeostasis, indicating that this might be a compensatory mechanism used by ameloblasts cells in the absence of Slc26 genes. Together, our data show that Slc26a1, Slc26a6 and Slc26a7 are novel participants in the extracellular transport of bicarbonate during enamel maturation, and that their functional roles may be achieved by forming interaction units with Cftr.
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Affiliation(s)
- Kaifeng Yin
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry of University of Southern California, Los Angeles, California, United States of America
| | - Yuejuan Lei
- Department of Operative and Endodontics, The Affiliated Stomatological Hospital, Guangxi Medical University, Nanning, Guangxi, China
| | - Xin Wen
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry of University of Southern California, Los Angeles, California, United States of America
| | - Rodrigo S. Lacruz
- Basic Science and Craniofacial Biology, New York University College of Dentistry, New York, New York, United States of America
| | - Manoocher Soleimani
- Department of Medicine, University of Cincinnati, Research Services, Veterans Affairs Medical Center, Cincinnati, Ohio, United States of America
| | - Ira Kurtz
- Division of Nephrology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, California, United States of America
| | - Malcolm L. Snead
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry of University of Southern California, Los Angeles, California, United States of America
| | - Shane N. White
- School of Dentistry, University of California Los Angeles, Los Angeles, California, United States of America
| | - Michael L. Paine
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry of University of Southern California, Los Angeles, California, United States of America
- * E-mail:
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106
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Effect of SLC26 anion transporter disease-causing mutations on the stability of the homologous STAS domain of E. coli DauA (YchM). Biochem J 2015; 473:615-26. [PMID: 26635355 DOI: 10.1042/bj20151025] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 12/03/2015] [Indexed: 01/08/2023]
Abstract
The human solute carrier 26 (SLC26) family of anion transporters consists of ten members that are found in various organs in the body including the stomach, intestine, kidney, thyroid and ear where they transport anions including bicarbonate, chloride and sulfate, typically in an exchange mode. Mutations in these genes cause a plethora of diseases such as diastrophic dysplasia affecting sulfate uptake into chondrocytes (SLC26A2), congenital chloride-losing diarrhoea (SLC26A3) affecting chloride secretion in the intestine and Pendred's syndrome (SLC26A4) resulting in hearing loss. To understand how these mutations affect the structures of the SLC26 membrane proteins and their ability to function properly, 12 human disease-causing mutants from SLC26A2, SLC26A3 and SLC26A4 were introduced into the equivalent sites of the sulfate transporter anti-sigma factor antagonist (STAS) domain of a bacterial homologue SLC26 protein DauA (YchM). Biophysical analyses including size-exclusion chromatography, circular dichroism (CD), differential scanning fluorimetry (DSF) and tryptophan fluorescence revealed that most mutations caused protein instability and aggregation. The mutation A463K, equivalent to N558K in human SLC26A4, which is located within α-helix 1 of the DauA STAS domain, stabilized the protein. CD measurements showed that most disease-related mutants had a mildly reduced helix content, but were more sensitive to thermal denaturation. Fluorescence spectroscopy showed that the mutants had more open structures and were more readily denatured by urea, whereas DSF indicated more labile folds. Overall, we conclude that the disease-associated mutations destabilized the STAS domain resulting in an increased propensity to misfold and aggregate.
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107
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Landry GM, Hirata T, Anderson JB, Cabrero P, Gallo CJR, Dow JAT, Romero MF. Sulfate and thiosulfate inhibit oxalate transport via a dPrestin (Slc26a6)-dependent mechanism in an insect model of calcium oxalate nephrolithiasis. Am J Physiol Renal Physiol 2015; 310:F152-9. [PMID: 26538444 DOI: 10.1152/ajprenal.00406.2015] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 10/30/2015] [Indexed: 11/22/2022] Open
Abstract
Nephrolithiasis is one of the most common urinary tract disorders, with the majority of kidney stones composed of calcium oxalate (CaOx). Given its prevalence (US occurrence 10%), it is still poorly understood, lacking progress in identifying new therapies because of its complex etiology. Drosophila melanogaster (fruitfly) is a recently developed model of CaOx nephrolithiasis. Effects of sulfate and thiosulfate on crystal formation were investigated using the Drosophila model, as well as electrophysiological effects on both Drosophila (Slc26a5/6; dPrestin) and mouse (mSlc26a6) oxalate transporters utilizing the Xenopus laevis oocyte heterologous expression system. Results indicate that both transport thiosulfate with a much higher affinity than sulfate Additionally, both compounds were effective at decreasing CaOx crystallization when added to the diet. However, these results were not observed when compounds were applied to Malpighian tubules ex vivo. Neither compound affected CaOx crystallization in dPrestin knockdown animals, indicating a role for principal cell-specific dPrestin in luminal oxalate transport. Furthermore, thiosulfate has a higher affinity for dPrestin and mSlc26a6 compared with oxalate These data indicate that thiosulfate's ability to act as a competitive inhibitor of oxalate via dPrestin, can explain the decrease in CaOx crystallization seen in the presence of thiosulfate, but not sulfate. Overall, our findings predict that thiosulfate or oxalate-mimics may be effective as therapeutic competitive inhibitors of CaOx crystallization.
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Affiliation(s)
- Greg M Landry
- Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, Minnesota; Nephrology and Hypertension, Mayo Clinic College of Medicine, Rochester, Minnesota; O'Brien Urology Research Center, Mayo Clinic College of Medicine, Rochester, Minnesota; and
| | - Taku Hirata
- Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, Minnesota; O'Brien Urology Research Center, Mayo Clinic College of Medicine, Rochester, Minnesota; and
| | - Jacob B Anderson
- Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Pablo Cabrero
- Institute of Molecular, Cell, and Systems Biology, College of Medical, Veterinary, and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Christopher J R Gallo
- Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Julian A T Dow
- O'Brien Urology Research Center, Mayo Clinic College of Medicine, Rochester, Minnesota; and Institute of Molecular, Cell, and Systems Biology, College of Medical, Veterinary, and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Michael F Romero
- Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, Minnesota; Nephrology and Hypertension, Mayo Clinic College of Medicine, Rochester, Minnesota; O'Brien Urology Research Center, Mayo Clinic College of Medicine, Rochester, Minnesota; and
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108
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Jalali R, Zandieh-Doulabi B, DenBesten PK, Seidler U, Riederer B, Wedenoja S, Micha D, Bronckers ALJJ. Slc26a3/Dra and Slc26a6 in Murine Ameloblasts. J Dent Res 2015; 94:1732-9. [PMID: 26394631 DOI: 10.1177/0022034515606873] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Formation of apatite crystals during enamel development generates protons. To sustain mineral accretion, maturation ameloblasts need to buffer these protons. The presence of cytosolic carbonic anhydrases, the basolateral Na(+) bicarbonate cotransporter Nbce1, and the basolateral anion exchanger Ae2a,b in maturation ameloblasts suggests that these cells secrete bicarbonates into the forming enamel, but it is unknown by which mechanism. Solute carrier (Slc) family 26A encodes different anion exchangers that exchange Cl(-)/HCO3 (-), including Slc26a3/Dra, Slc26a6/Pat-1, and Slc26a4/pendrin. Previously, we showed that pendrin is expressed in ameloblasts but is not critical for enamel formation. In this study, we tested the hypothesis that maturation ameloblasts express Dra and Slc26a6 to secrete bicarbonate into the enamel space in exchange for Cl(-). Real-time polymerase chain reaction detected mRNA transcripts for Dra and Slc26a6 in mouse incisor enamel organs, and Western blotting confirmed their translation into protein. Both isoforms were immunolocalized in ameloblasts, principally at maturation stage. Mice with null mutation of either Dra or Slc26a6 had a normal dental or skeletal phenotype without changes in mineral density, as measured by micro-computed tomography. In enamel organs of Slc26a6-null mice, Dra and pendrin protein levels were both elevated by 52% and 55%, respectively. The amount of Slc26a6 protein was unchanged in enamel organs of Ae2a,b- and Cftr-null mice but reduced in Dra-null mice by 36%. Our data show that ameloblasts express Dra, pendrin, or Slc26a6 but each of these separately is not critical for formation of dental enamel. The data suggest that in ameloblasts, Slc26a isoforms can functionally compensate for one another.
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Affiliation(s)
- R Jalali
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam, University of Amsterdam, and MOVE Research Institute, VU University Amsterdam, Amsterdam, Netherlands
| | - B Zandieh-Doulabi
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam, University of Amsterdam, and MOVE Research Institute, VU University Amsterdam, Amsterdam, Netherlands
| | - P K DenBesten
- Department of Oral Sciences, University of California, San Francisco, CA, USA
| | - U Seidler
- Abteilung Gastroenterologie, Hepatologie und Endokrinologie, Medizinische Hochschule Hannover, Hannover, Germany
| | - B Riederer
- Abteilung Gastroenterologie, Hepatologie und Endokrinologie, Medizinische Hochschule Hannover, Hannover, Germany
| | - S Wedenoja
- Department of Medical Genetics, Biomedicum Helsinki, University of Helsinki, Finland
| | - D Micha
- Department of Clinical Genetics, Vrije Universiteit Medical Center, Amsterdam, Netherlands
| | - A L J J Bronckers
- Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam, University of Amsterdam, and MOVE Research Institute, VU University Amsterdam, Amsterdam, Netherlands
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109
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Balázs A, Ruffert C, Hegyi E, Hritz I, Czakó L, Takács T, Szepes Z, Németh BC, Gervain J, Izbéki F, Halász A, Kelemen D, Szmola R, Novák J, Crai S, Illés A, Vincze Á, Molnár Z, Varga M, Bod B, Farkas G, Sümegi J, Szepes A, Dubravcsik Z, Lásztity N, Párniczky A, Hamvas J, Andorka C, Veres G, Szentkereszty Z, Rakonczay Z, Maléth J, Sahin-Tóth M, Rosendahl J, Hegyi P. Genetic analysis of the bicarbonate secreting anion exchanger SLC26A6 in chronic pancreatitis. Pancreatology 2015; 15:508-513. [PMID: 26372434 DOI: 10.1016/j.pan.2015.08.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Revised: 08/19/2015] [Accepted: 08/21/2015] [Indexed: 12/11/2022]
Abstract
BACKGROUND Pancreatic ductal HCO3(-) secretion is critically dependent on the cystic fibrosis transmembrane conductance regulator chloride channel (CFTR) and the solute-linked carrier 26 member 6 anion transporter (SLC26A6). Deterioration of HCO3(-) secretion is observed in chronic pancreatitis (CP), and CFTR mutations increase CP risk. Therefore, SLC26A6 is a reasonable candidate for a CP susceptibility gene, which has not been investigated in CP patients so far. METHODS As a first screening cohort, 106 subjects with CP and 99 control subjects with no pancreatic disease were recruited from the Hungarian National Pancreas Registry. In 60 non-alcoholic CP cases the entire SLC26A6 coding region was sequenced. In the Hungarian cohort variants c.616G > A (p.V206M) and c.1191C > A (p.P397=) were further genotyped by restriction fragment length polymorphism analysis. In a German replication cohort all exons were sequenced in 40 non-alcoholic CP cases and variant c.616G > A (p.V206M) was further analyzed by sequencing in 321 CP cases and 171 controls. RESULTS Sequencing of the entire coding region revealed four common variants: intronic variants c.23 + 78_110del, c.183-4C > A, c.1134 + 32C > A, and missense variant c.616G > A (p.V206M) which were found in linkage disequilibrium indicating a conserved haplotype. The distribution of the haplotype did not show a significant difference between patients and controls in the two cohorts. A synonymous variant c.1191C > A (p.P397=) and two intronic variants c.1248 + 9_20del and c.-10C > T were detected in single cases. CONCLUSION Our data show that SLC26A6 variants do not alter the risk for the development of CP.
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Affiliation(s)
- Anita Balázs
- First Department of Medicine, University of Szeged, Szeged, Hungary
| | - Claudia Ruffert
- Department of Internal Medicine, Neurology and Dermatology, Division of Gastroenterology and Rheumatology, University of Leipzig, Leipzig, Germany
| | - Eszter Hegyi
- First Department of Medicine, University of Szeged, Szeged, Hungary; 2nd Department of Pediatrics, Comenius University Medical School, University Children's Hospital, Bratislava, Slovakia
| | - István Hritz
- First Department of Medicine, University of Szeged, Szeged, Hungary
| | - László Czakó
- First Department of Medicine, University of Szeged, Szeged, Hungary
| | - Tamás Takács
- First Department of Medicine, University of Szeged, Szeged, Hungary
| | - Zoltán Szepes
- First Department of Medicine, University of Szeged, Szeged, Hungary
| | - Balázs Csaba Németh
- Department of Molecular and Cell Biology, Boston University Henry M. Goldman School of Dental Medicine, Boston, MA 02118, USA
| | - Judit Gervain
- Szent György University Teaching Hospital of County Fejér, Székesfehérvár, Hungary
| | - Ferenc Izbéki
- Szent György University Teaching Hospital of County Fejér, Székesfehérvár, Hungary
| | - Adrienn Halász
- Szent György University Teaching Hospital of County Fejér, Székesfehérvár, Hungary
| | | | - Richárd Szmola
- Department of Interventional Gastroenterology, National Institute of Oncology, Budapest, Hungary
| | - János Novák
- Pándy Kálmán County Hopsital, Gyula, Hungary
| | - Stefan Crai
- Pándy Kálmán County Hopsital, Gyula, Hungary
| | - Anita Illés
- First Department of Medicine, University of Pécs, Hungary
| | - Áron Vincze
- First Department of Medicine, University of Pécs, Hungary
| | - Zsolt Molnár
- Department of Anestesiology and Intensive Care, University of Szeged, Szeged, Hungary
| | | | | | - Gyula Farkas
- Department of Surgery, University of Szeged, Hungary
| | - János Sümegi
- B-A-Z County Hopspital and University Teaching Hospital, Miskolc, Hungary
| | - Attila Szepes
- Department of Gastroenterology, Bács-Kiskun County Hospital, Kecskemét, Hungary
| | - Zsolt Dubravcsik
- Department of Gastroenterology, Bács-Kiskun County Hospital, Kecskemét, Hungary
| | | | | | | | - Csilla Andorka
- 1st Department of Pediatrics, Semmelweis University, Faculty of Medicine, Budapest, Hungary
| | - Gábor Veres
- 1st Department of Pediatrics, Semmelweis University, Faculty of Medicine, Budapest, Hungary
| | - Zsolt Szentkereszty
- Institute of Surgery, University of Debrecen, Clinical Center, Debrecen Hungary
| | - Zoltán Rakonczay
- First Department of Medicine, University of Szeged, Szeged, Hungary
| | - József Maléth
- First Department of Medicine, University of Szeged, Szeged, Hungary
| | - Miklós Sahin-Tóth
- Department of Molecular and Cell Biology, Boston University Henry M. Goldman School of Dental Medicine, Boston, MA 02118, USA
| | - Jonas Rosendahl
- Department of Internal Medicine, Neurology and Dermatology, Division of Gastroenterology and Rheumatology, University of Leipzig, Leipzig, Germany
| | - Péter Hegyi
- First Department of Medicine, University of Szeged, Szeged, Hungary; MTA-SZTE Translational Gastroenterology Research Group, Szeged, Hungary.
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110
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Whittamore JM, Hatch M. Chronic metabolic acidosis reduces urinary oxalate excretion and promotes intestinal oxalate secretion in the rat. Urolithiasis 2015; 43:489-99. [DOI: 10.1007/s00240-015-0801-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Accepted: 06/30/2015] [Indexed: 11/30/2022]
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111
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Oxalobacter formigenes Colonization and Oxalate Dynamics in a Mouse Model. Appl Environ Microbiol 2015; 81:5048-54. [PMID: 25979889 DOI: 10.1128/aem.01313-15] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Accepted: 05/12/2015] [Indexed: 11/20/2022] Open
Abstract
Animal and human studies have provided compelling evidence that colonization of the intestine with Oxalobacter formigenes reduces urinary oxalate excretion and lowers the risk of forming calcium oxalate kidney stones. The mechanism providing protection appears to be related to the unique ability of O. formigenes to rely on oxalate as a major source of carbon and energy for growth. However, much is not known about the factors that influence colonization and host-bacterium interactions. We have colonized mice with O. formigenes OxCC13 and systematically investigated the impacts of diets with different levels of calcium and oxalate on O. formigenes intestinal densities and urinary and intestinal oxalate levels. Measurement of intestinal oxalate levels in mice colonized or not colonized with O. formigenes demonstrated the highly efficient degradation of soluble oxalate by O. formigenes relative to other microbiota. The ratio of calcium to oxalate in diets was important in determining colonization densities and conditions where urinary oxalate and fecal oxalate excretion were modified, and the results were consistent with those from studies we have performed with colonized and noncolonized humans. The use of low-oxalate purified diets showed that 80% of animals retained O. formigenes colonization after a 1-week dietary oxalate deprivation. Animals not colonized with O. formigenes excreted two times more oxalate in feces than they had ingested. This nondietary source of oxalate may play an important role in the survival of O. formigenes during periods of dietary oxalate deprivation. These studies suggest that the mouse will be a useful model to further characterize interactions between O. formigenes and the host and factors that impact colonization.
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112
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A Drosophila model identifies a critical role for zinc in mineralization for kidney stone disease. PLoS One 2015; 10:e0124150. [PMID: 25970330 PMCID: PMC4430225 DOI: 10.1371/journal.pone.0124150] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 03/11/2015] [Indexed: 12/14/2022] Open
Abstract
Ectopic calcification is a driving force for a variety of diseases, including kidney stones and atherosclerosis, but initiating factors remain largely unknown. Given its importance in seemingly divergent disease processes, identifying fundamental principal actors for ectopic calcification may have broad translational significance. Here we establish a Drosophila melanogaster model for ectopic calcification by inhibiting xanthine dehydrogenase whose deficiency leads to kidney stones in humans and dogs. Micro X-ray absorption near edge spectroscopy (μXANES) synchrotron analyses revealed high enrichment of zinc in the Drosophila equivalent of kidney stones, which was also observed in human kidney stones and Randall's plaques (early calcifications seen in human kidneys thought to be the precursor for renal stones). To further test the role of zinc in driving mineralization, we inhibited zinc transporter genes in the ZnT family and observed suppression of Drosophila stone formation. Taken together, genetic, dietary, and pharmacologic interventions to lower zinc confirm a critical role for zinc in driving the process of heterogeneous nucleation that eventually leads to stone formation. Our findings open a novel perspective on the etiology of urinary stones and related diseases, which may lead to the identification of new preventive and therapeutic approaches.
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113
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Bhasin B, Ürekli HM, Atta MG. Primary and secondary hyperoxaluria: Understanding the enigma. World J Nephrol 2015; 4:235-244. [PMID: 25949937 PMCID: PMC4419133 DOI: 10.5527/wjn.v4.i2.235] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 08/29/2014] [Accepted: 02/09/2015] [Indexed: 02/05/2023] Open
Abstract
Hyperoxaluria is characterized by an increased urinary excretion of oxalate. Primary and secondary hyperoxaluria are two distinct clinical expressions of hyperoxaluria. Primary hyperoxaluria is an inherited error of metabolism due to defective enzyme activity. In contrast, secondary hyperoxaluria is caused by increased dietary ingestion of oxalate, precursors of oxalate or alteration in intestinal microflora. The disease spectrum extends from recurrent kidney stones, nephrocalcinosis and urinary tract infections to chronic kidney disease and end stage renal disease. When calcium oxalate burden exceeds the renal excretory ability, calcium oxalate starts to deposit in various organ systems in a process called systemic oxalosis. Increased urinary oxalate levels help to make the diagnosis while plasma oxalate levels are likely to be more accurate when patients develop chronic kidney disease. Definitive diagnosis of primary hyperoxaluria is achieved by genetic studies and if genetic studies prove inconclusive, liver biopsy is undertaken to establish diagnosis. Diagnostic clues pointing towards secondary hyperoxaluria are a supportive dietary history and tests to detect increased intestinal absorption of oxalate. Conservative treatment for both types of hyperoxaluria includes vigorous hydration and crystallization inhibitors to decrease calcium oxalate precipitation. Pyridoxine is also found to be helpful in approximately 30% patients with primary hyperoxaluria type 1. Liver-kidney and isolated kidney transplantation are the treatment of choice in primary hyperoxaluria type 1 and type 2 respectively. Data is scarce on role of transplantation in primary hyperoxaluria type 3 where there are no reports of end stage renal disease so far. There are ongoing investigations into newer modalities of diagnosis and treatment of hyperoxaluria. Clinical differentiation between primary and secondary hyperoxaluria and further between the types of primary hyperoxaluria is very important because of implications in treatment and diagnosis. Hyperoxaluria continues to be a challenging disease and a high index of clinical suspicion is often the first step on the path to accurate diagnosis and management.
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114
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Pierucci-Alves F, Akoyev V, Schultz BD. Bicarbonate exchangers SLC26A3 and SLC26A6 are localized at the apical membrane of porcine vas deferens epithelium. Physiol Rep 2015; 3:3/4/e12380. [PMID: 25907791 PMCID: PMC4425982 DOI: 10.14814/phy2.12380] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The goal of this study was to test for expression of HCO3 (-) exchangers SLC26A3 and SLC26A6 in primary cultures of porcine vas deferens epithelial cells (1°PVD) and native porcine vas deferens. Quantitative RT-PCR revealed that mRNA coding for SLC26A6 was six times more abundant than mRNA coding for SLC26A3 in 1°PVD cells. Western blot analyses combined with surface biotinylation of 1°PVD demonstrated SLC26A3 and SLC26A6 immunoreactivities in whole-cell lysates and apical surfaces of monolayers. Laser scanning confocal microscopy (LSCM) of the 1°PVD cell monolayers demonstrated that SLC26A3 immunoreactivity was primarily in the apical region but present throughout the basal-apical cellular axis, whereas SLC26A6 immunoreactivity was present in the apical region and sometimes accumulated in the nuclear region. LSCM also demonstrated SLC26A3 and SLC26A6 immunoreactivities present along the entire apical lining of the native porcine vas deferens epithelium and in basal cells. The patterns and apparent abundance of SLC26A3 and SLC26A6 immunoreactivities in the proximal vas deferens were not different from the corresponding immunoreactivities in the distal region. There is no evidence of preferential expression of SLC26A3 or SLC26A6 in any portion of the vas deferens, as has been proposed for epithelia that secrete HCO3 (-) in other duct systems. Thus, vas deferens epithelia express transporters throughout the duct that can contribute to rapid alkalinization of the luminal contents as it has been demonstrated in vivo.
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Affiliation(s)
| | - Vladimir Akoyev
- Department of Anatomy & Physiology, Kansas State University, Manhattan, Kansas, USA
| | - Bruce D Schultz
- Department of Anatomy & Physiology, Kansas State University, Manhattan, Kansas, USA
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115
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Gulhan B, Turkmen K, Aydin M, Gunay M, Cıkman A, Kara M. The Relationship between Serum Oxalic Acid, Central Hemodynamic Parameters and Colonization by Oxalobacter formigenes in Hemodialysis Patients. Cardiorenal Med 2015. [PMID: 26195968 DOI: 10.1159/000381219] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/OBJECTIVE Elevated pulse wave velocity (PWV) and central aortic blood pressures are independent predictors of increased cardiovascular morbidity and mortality in hemodialysis (HD) patients. Oxalic acid is a uremic retention molecule that is extensively studied in the pathogenesis of calcium oxalate stones. Oxalobacter formigenes, a member of the colon microbiota, has important roles in oxalate homeostasis. Data regarding the colonization by and the exact role of O. formigenes in the pathogenesis of oxalic acid metabolism in HD patients are scant. Hence, we aimed to determine the relationship between fecal O. formigenes colonization, serum oxalic acid and hemodynamic parameters in HD patients with regard to the colo-reno-cardiac axis. METHODS Fifty HD patients were enrolled in this study. PWV and central aortic systolic (cASBP) and diastolic blood pressures (cADBP) were measured with a Mobil-O-Graph (I.E.M. GmbH, Stolberg, Germany). Serum oxalic acid levels were assessed by ELISA, and fecal O. formigenes DNA levels were isolated and measured by real-time PCR. RESULTS Isolation of fecal O. formigenes was found in only 2 HD patients. One of them had 113,609 copies/ml, the other one had 1,056 copies/ml. Serum oxalic acid levels were found to be positively correlated with PWV (r = 0.29, p = 0.03), cASBP (r = 0.33, p = 0.001) and cADBP (r = 0.42, p = 0.002) and negatively correlated with LDL (r = -0.30, p = 0.03). In multivariate linear regression analysis, PWV was independently predicted by oxalic acid, glucose and triglyceride. CONCLUSIONS This is the first study that demonstrates the absence of O. formigenes as well as a relation between serum oxalic acid and cASBP, cADBP and PWV in HD patients. Replacement of O. formigenes with pre- and probiotics might decrease serum oxalic acid levels and improve cardiovascular outcomes in HD patients.
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Affiliation(s)
- Baris Gulhan
- Department of Microbiology, Erzincan University, Erzincan, Konya, Turkey
| | - Kultigin Turkmen
- Division of Nephrology, Department of Internal Medicine, Meram School of Medicine, Konya Necmettin Erbakan University, Konya, Turkey
| | - Merve Aydin
- Department of Microbiology, Erzincan University, Erzincan, Konya, Turkey
| | - Murat Gunay
- Department of Biochemistry, School of Medicine, Erzincan University, Erzincan, Konya, Turkey
| | - Aytekin Cıkman
- Department of Microbiology, Erzincan University, Erzincan, Konya, Turkey
| | - Murat Kara
- Department of Microbiology, Erzincan University, Erzincan, Konya, Turkey
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116
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Krieger NS, Asplin JR, Frick KK, Granja I, Culbertson CD, Ng A, Grynpas MD, Bushinsky DA. Effect of Potassium Citrate on Calcium Phosphate Stones in a Model of Hypercalciuria. J Am Soc Nephrol 2015; 26:3001-8. [PMID: 25855777 DOI: 10.1681/asn.2014121223] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Accepted: 02/02/2015] [Indexed: 01/24/2023] Open
Abstract
Potassium citrate is prescribed to decrease stone recurrence in patients with calcium nephrolithiasis. Citrate binds intestinal and urine calcium and increases urine pH. Citrate, metabolized to bicarbonate, should decrease calcium excretion by reducing bone resorption and increasing renal calcium reabsorption. However, citrate binding to intestinal calcium may increase absorption and renal excretion of both phosphate and oxalate. Thus, the effect of potassium citrate on urine calcium oxalate and calcium phosphate supersaturation and stone formation is complex and difficult to predict. To study the effects of potassium citrate on urine supersaturation and stone formation, we utilized 95th-generation inbred genetic hypercalciuric stone-forming rats. Rats were fed a fixed amount of a normal calcium (1.2%) diet supplemented with potassium citrate or potassium chloride (each 4 mmol/d) for 18 weeks. Urine was collected at 6, 12, and 18 weeks. At 18 weeks, stone formation was visualized by radiography. Urine citrate, phosphate, oxalate, and pH levels were higher and urine calcium level was lower in rats fed potassium citrate. Furthermore, calcium oxalate and calcium phosphate supersaturation were higher with potassium citrate; however, uric acid supersaturation was lower. Both groups had similar numbers of exclusively calcium phosphate stones. Thus, potassium citrate effectively raises urine citrate levels and lowers urine calcium levels; however, the increases in urine pH, oxalate, and phosphate levels lead to increased calcium oxalate and calcium phosphate supersaturation. Potassium citrate induces complex changes in urine chemistries and resultant supersaturation, which may not be beneficial in preventing calcium phosphate stone formation.
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Affiliation(s)
- Nancy S Krieger
- Division of Nephrology, Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York;
| | - John R Asplin
- Litholink Corporation, Laboratory Corporation of America Holdings, Chicago, Illinois; and
| | - Kevin K Frick
- Division of Nephrology, Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York
| | - Ignacio Granja
- Litholink Corporation, Laboratory Corporation of America Holdings, Chicago, Illinois; and
| | - Christopher D Culbertson
- Division of Nephrology, Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York
| | - Adeline Ng
- Laboratory Medicine and Pathobiology Department, University of Toronto, Toronto, Ontario, Canada
| | - Marc D Grynpas
- Laboratory Medicine and Pathobiology Department, University of Toronto, Toronto, Ontario, Canada
| | - David A Bushinsky
- Division of Nephrology, Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York
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117
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Whittamore JM, Frost SC, Hatch M. Effects of acid-base variables and the role of carbonic anhydrase on oxalate secretion by the mouse intestine in vitro. Physiol Rep 2015; 3:e12282. [PMID: 25716924 PMCID: PMC4393191 DOI: 10.14814/phy2.12282] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Revised: 12/06/2014] [Accepted: 12/30/2014] [Indexed: 12/15/2022] Open
Abstract
Hyperoxaluria is a major risk factor for calcium oxalate kidney stones and the intestine is recognized as an important extra-renal pathway for eliminating oxalate. The membrane-bound chloride/bicarbonate (Cl(-)/) exchangers are involved in the transcellular movement of oxalate, but little is understood about how they might be regulated. , CO2, and pH are established modulators of intestinal NaCl cotransport, involving Na(+)/H(+) and Cl(-)/ exchange, but their influence on oxalate transport is unknown. Measuring (14)C-oxalate and (36)Cl fluxes across isolated, short-circuited segments of the mouse distal ileum and distal colon we examined the role of these acid-base variables and carbonic anhydrase (CA) in oxalate and Cl(-) transport. In standard buffer both segments performed net oxalate secretion (and Cl(-) absorption), but only the colon, and the secretory pathway were responsive to and CO2. Ethoxzolamide abolished net oxalate secretion by the distal colon, and when used in tandem with an impermeant CA inhibitor, signaled an intracellular CA isozyme was required for secretion. There was a clear dependence on as their removal eliminated secretion, while at 42 mmol/L was also decreased and eradicated. Independent of pH, raising Pco2 from 28 to 64 mmHg acutely stimulated net oxalate secretion 41%. In summary, oxalate secretion by the distal colon was dependent on , CA and specifically modulated by CO2, whereas the ileum was remarkably unresponsive. These findings highlight the distinct segmental heterogeneity along the intestine, providing new insights into the oxalate transport mechanism and how it might be regulated.
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Affiliation(s)
- Jonathan M Whittamore
- Department of Pathology, Immunology and Laboratory Medicine, College of Medicine, University of FloridaGainesville, Florida, USA
| | - Susan C Frost
- Department of Biochemistry and Molecular Biology, College of Medicine, University of FloridaGainesville, Florida, USA
| | - Marguerite Hatch
- Department of Pathology, Immunology and Laboratory Medicine, College of Medicine, University of FloridaGainesville, Florida, USA
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118
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Turkmen K, Erdur FM. The relationship between colonization of Oxalobacter formigenes serum oxalic acid and endothelial dysfunction in hemodialysis patients: from impaired colon to impaired endothelium. Med Hypotheses 2015; 84:273-5. [PMID: 25630805 DOI: 10.1016/j.mehy.2015.01.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Revised: 01/08/2015] [Accepted: 01/13/2015] [Indexed: 11/24/2022]
Abstract
Cardiovascular disease (CVD) remains the leading cause of morbidity and mortality in chronic kidney disease (CKD) patients receiving hemodialysis (HD). Oxalic acid is a uremic retention molecule that has been extensively studied in the pathogenesis of calcium-oxalate stones. Oxalobacter formigenes (O. formigenes), a component of the colonic microbiota, plays an important role in oxalate homeostasis. Little is known regarding the colonization of HD patients by O. formigenes and the exact role of this bacterial species in oxalic acid metabolism in these patients. We hypothesized that oxalic acid may be insufficiently degraded in HD patients due to under colonization of the colon by O. formigenes in these patients. To test this hypothesis, we sought to quantitatively measure fecal O. formigenes levels and serum oxalic acid levels in HD patients. We also suggest that increased oxalic acid levels may be associated with endothelial dysfunction and aortic stiffness, both of which are commonly observed in HD patients. Increased colonization with O. formigenes via the ingestion of prebiotics and probiotics could potentially decrease serum oxalic acid levels and improve cardiovascular outcomes in HD patients.
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Affiliation(s)
- K Turkmen
- Department of Nephrology, School of Medicine, Konya Necmettin Erbakan University, Meram School of Medicine, Konya, Turkey.
| | - F M Erdur
- Department of Nephrology, School of Medicine, Konya Necmettin Erbakan University, Meram School of Medicine, Konya, Turkey
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119
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Alka K, Casey JR. Bicarbonate transport in health and disease. IUBMB Life 2014; 66:596-615. [PMID: 25270914 DOI: 10.1002/iub.1315] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Accepted: 09/10/2014] [Indexed: 12/28/2022]
Abstract
Bicarbonate (HCO3(-)) has a central place in human physiology as the waste product of mitochondrial energy production and for its role in pH buffering throughout the body. Because bicarbonate is impermeable to membranes, bicarbonate transport proteins are necessary to enable control of bicarbonate levels across membranes. In humans, 14 bicarbonate transport proteins, members of the SLC4 and SLC26 families, function by differing transport mechanisms. In addition, some anion channels and ZIP metal transporters contribute to bicarbonate movement across membranes. Defective bicarbonate transport leads to diseases, including systemic acidosis, brain dysfunction, kidney stones, and hypertension. Altered expression levels of bicarbonate transporters in patients with breast, colon, and lung cancer suggest an important role of these transporters in cancer.
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Affiliation(s)
- Kumari Alka
- Department of Biochemistry, University of Alberta, Edmonton, AB, Canada
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120
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Farmanesh S, Chung J, Sosa RD, Kwak JH, Karande P, Rimer JD. Natural promoters of calcium oxalate monohydrate crystallization. J Am Chem Soc 2014; 136:12648-57. [PMID: 25119124 DOI: 10.1021/ja505402r] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Crystallization is often facilitated by modifiers that interact with specific crystal surfaces and mediate the anisotropic rate of growth. Natural and synthetic modifiers tend to function as growth inhibitors that hinder solute attachment and impede the advancement of layers on crystal surfaces. There are fewer examples of modifiers that operate as growth promoters, whereby modifier-crystal interactions accelerate the kinetic rate of crystallization. Here, we examine two proteins, lysozyme and lactoferrin, which are observed in the organic matrix of three types of pathological stones: renal, prostatic, and pancreatic stones. This work focuses on the role of these proteins in the crystallization of calcium oxalate monohydrate (COM), the most prominent constituent of human kidney stones. Using a combination of experimental techniques, we show that these proteins, which are rich in l-arginine and l-lysine amino acids, promote COM growth. The synthesis and testing of peptides derived from contiguous segments of lysozyme's primary amino acid sequence revealed subdomains within the protein that operate either as an inhibitor or promoter of COM growth, with the latter exhibiting efficacies that nearly match that of the protein. We observed that cationic proteins promote COM growth over a wide range of modifier concentration, which differs from calcification promoters in the literature that exhibit dual roles as promoters and inhibitors at low and high concentration, respectively. This seems to suggest a unique mechanism of action for lysozyme and lactoferrin. Possible explanations for their effects on COM growth and crystal habit are proposed on the basis of classical colloidal theories and the physicochemical properties of peptide subdomains, including the number and spatial location of charged or hydrogen-bonding moieties.
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Affiliation(s)
- Sahar Farmanesh
- Department of Chemical and Biomolecular Engineering, University of Houston , Houston, Texas 77204, United States
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121
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Evan AP, Worcester EM, Coe FL, Williams J, Lingeman JE. Mechanisms of human kidney stone formation. Urolithiasis 2014; 43 Suppl 1:19-32. [PMID: 25108546 DOI: 10.1007/s00240-014-0701-0] [Citation(s) in RCA: 107] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 07/23/2014] [Indexed: 01/08/2023]
Abstract
The precise mechanisms of kidney stone formation and growth are not completely known, even though human stone disease appears to be one of the oldest diseases known to medicine. With the advent of the new digital endoscope and detailed renal physiological studies performed on well phenotyped stone formers, substantial advances have been made in our knowledge of the pathogenesis of the most common type of stone former, the idiopathic calcium oxalate stone former as well as nine other stone forming groups. The observations from our group on human stone formers and those of others on model systems have suggested four entirely different pathways for kidney stone formation. Calcium oxalate stone growth over sites of Randall's plaque appear to be the primary mode of stone formation for those patients with hypercalciuria. Overgrowths off the ends of Bellini duct plugs have been noted in most stone phenotypes, do they result in a clinical stone? Micro-lith formation does occur within the lumens of dilated inner medullary collecting ducts of cystinuric stone formers and appear to be confined to this space. Lastly, cystinuric stone formers also have numerous small, oval, smooth yellow appearing calyceal stones suggestive of formation in free solution. The scientific basis for each of these four modes of stone formation are reviewed and used to explore novel research opportunities.
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Affiliation(s)
- Andrew P Evan
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, 635 Barnhill Drive, MS 5055, Indianapolis, IN, 46220, USA,
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122
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Ferraz RRN, Fonseca JM, Germino GG, Onuchic LF, Heilberg IP. Determination of urinary lithogenic parameters in murine models orthologous to autosomal dominant polycystic kidney disease. Urolithiasis 2014; 42:301-7. [PMID: 24817661 PMCID: PMC5602548 DOI: 10.1007/s00240-014-0664-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Accepted: 04/15/2014] [Indexed: 10/25/2022]
Abstract
Autosomal dominant polycystic kidney disease (ADPKD), a genetic disease caused by mutations in PKD1 or PKD2 genes, is associated with a high prevalence of nephrolithiasis. The underlying mechanisms may encompass structural abnormalities resulting from cyst growth, urinary metabolic abnormalities or both. An increased frequency of hypocitraturia has been described in ADPKD even in the absence of nephrolithiasis, suggesting that metabolic alterations may be associated with ADPKD per se. We aimed to investigate whether non-cystic Pkd1-haploinsufficient (Pkd1(+/-)) and/or nestin-Cre Pkd1-targeted cystic (Pkd1(cond/cond):Nestin(cre)) mouse models develop urinary metabolic abnormalities potentially related to nephrolithiasis in ADPKD. 24-h urine samples were collected during three non-consecutive days from 10-12 and 18-20 week-old animals. At 10-12 weeks of age, urinary oxalate, calcium, magnesium, citrate and uric acid did not differ between test and their respective control groups. At 18-20 weeks, Pkd1(+/-) showed slightly but significantly higher urinary uric acid vs. controls while cystic animals did not. The absence of hypocitraturia, hyperoxaluria and hyperuricosuria in the cystic model at both ages and the finding of hyperuricosuria in the 18-20 week-old animals suggest that anatomic cystic distortions per se do not generate the metabolic disturbances described in human ADPKD-related nephrolithiasis, while Pkd1 haploinsufficiency may contribute to this phenotype in this animal model.
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Affiliation(s)
| | | | | | - Luiz Fernando Onuchic
- Division of Nephrology, University of Sao Paulo School of Medicine, Sao Paulo, Brazil
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123
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Springer DA, Allen M, Hoffman V, Brinster L, Starost MF, Bryant M, Eckhaus M. Investigation and identification of etiologies involved in the development of acquired hydronephrosis in aged laboratory mice with the use of high-frequency ultrasound imaging. PATHOBIOLOGY OF AGING & AGE RELATED DISEASES 2014; 4:24932. [PMID: 25143818 PMCID: PMC4119937 DOI: 10.3402/pba.v4.24932] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Accepted: 06/16/2014] [Indexed: 11/14/2022]
Abstract
Laboratory mice develop naturally occurring lesions that affect biomedical research. Hydronephrosis is a recognized pathologic abnormality of the mouse kidney. Acquired hydronephrosis can affect any mouse, as it is caused by any naturally occurring disease that impairs free urine flow. Many etiologies leading to this condition are of particular significance to aging mice. Non-invasive ultrasound imaging detects renal pelvic dilation, renal enlargement, and parenchymal loss for pre-mortem identification of this condition. High-frequency ultrasound transducers produce high-resolution images of small structures, ideal for detecting organ pathology in mice. Using a 40 MHz linear array transducer, we obtained high-resolution images of a diversity of pathologic lesions occurring within the abdomen of seven geriatric mice with acquired hydronephrosis that enabled a determination of the underlying etiology. Etiologies diagnosed from the imaging results include pyelonephritis, neoplasia, urolithiasis, mouse urologic syndrome, and spontaneous hydronephrosis, and were confirmed at necropsy. A retrospective review of abdominal scans from an additional 149 aging mice shows that the most common etiologies associated with acquired hydronephrosis are mouse urologic syndrome and abdominal neoplasia. This report highlights the utility of high-frequency ultrasound for surveying research mice for age-related pathology, and is the first comprehensive report of multiple cases of acquired hydronephrosis in mice.
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Affiliation(s)
- Danielle A. Springer
- Murine Phenotyping Core, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Michele Allen
- Murine Phenotyping Core, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Victoria Hoffman
- Office of Research Services, Division of Veterinary Resources, National Institutes of Health, Bethesda, MD, USA
| | - Lauren Brinster
- Office of Research Services, Division of Veterinary Resources, National Institutes of Health, Bethesda, MD, USA
| | - Matthew F. Starost
- Office of Research Services, Division of Veterinary Resources, National Institutes of Health, Bethesda, MD, USA
| | - Mark Bryant
- Office of Research Services, Division of Veterinary Resources, National Institutes of Health, Bethesda, MD, USA
| | - Michael Eckhaus
- Office of Research Services, Division of Veterinary Resources, National Institutes of Health, Bethesda, MD, USA
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124
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Lactobacillus casei reduces susceptibility to type 2 diabetes via microbiota-mediated body chloride ion influx. Sci Rep 2014; 4:5654. [PMID: 25133590 PMCID: PMC4135721 DOI: 10.1038/srep05654] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Accepted: 06/24/2014] [Indexed: 12/30/2022] Open
Abstract
Gut microbiota mediated low-grade inflammation is involved in the onset of type 2 diabetes (T2DM). In this study, we used a high fat sucrose (HFS) diet-induced pre-insulin resistance and a low dose-STZ HFS rat models to study the effect and mechanism of Lactobacillus casei Zhang in protecting against T2DM onset. Hyperglycemia was favorably suppressed by L. casei Zhang treatment. Moreover, the hyperglycemia was connected with type 1 immune response, high plasma bile acids and urine chloride ion loss. This chloride ion loss was significantly prevented by L. casei via upregulating of chloride ion-dependent genes (ClC1-7, GlyRα1, SLC26A3, SLC26A6, GABAAα1, Bestrophin-3 and CFTR). A shift in the caecal microflora, particularly the reduction of bile acid 7α-dehydroxylating bacteria, and fecal bile acid profiles also occurred. These change coincided with organ chloride influx. Thus, we postulate that the prevention of T2DM onset by L. casei Zhang may be via a microbiota-based bile acid-chloride exchange mechanism.
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125
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Karaolanis G, Lionaki S, Moris D, Palla VV, Vernadakis S. Secondary hyperoxaluria: a risk factor for kidney stone formation and renal failure in native kidneys and renal grafts. Transplant Rev (Orlando) 2014; 28:182-7. [PMID: 24999029 DOI: 10.1016/j.trre.2014.05.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2013] [Revised: 05/18/2014] [Accepted: 05/21/2014] [Indexed: 12/22/2022]
Abstract
Secondary hyperoxaluria is a multifactorial disease affecting several organs and tissues, among which stand native and transplanted kidneys. Nephrocalcinosis and nephrolithiasis may lead to renal insufficiency. Patients suffering from secondary hyperoxaluria, should be promptly identified and appropriately treated, so that less renal damage occurs. The aim of this review is to underline the causes of hyperoxaluria and the related pathophysiologic mechanisms, which are involved, along with the description of seven cases of irreversible renal graft injury due to secondary hyperoxaluria.
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Affiliation(s)
- Georgios Karaolanis
- Transplantation Unit, Laiko General Hospital, Medical School of Athens, Athens, Greece.
| | - Sophia Lionaki
- Nephrology and Transplantation Unit, Laiko Hospital, Athens, Greece
| | - Demetrios Moris
- Transplantation Unit, Laiko General Hospital, Medical School of Athens, Athens, Greece
| | | | - Spiridon Vernadakis
- Transplantation Unit, Laiko General Hospital, Medical School of Athens, Athens, Greece
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126
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Xu A, Szczepanek K, Maceyka MW, Ross T, Bowler E, Hu Y, Kenny B, Mehfoud C, Desai PN, Baumgarten CM, Chen Q, Lesnefsky EJ. Transient complex I inhibition at the onset of reperfusion by extracellular acidification decreases cardiac injury. Am J Physiol Cell Physiol 2014; 306:C1142-53. [PMID: 24696146 DOI: 10.1152/ajpcell.00241.2013] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
A reversible inhibition of mitochondrial respiration by complex I inhibition at the onset of reperfusion decreases injury in buffer-perfused hearts. Administration of acidic reperfusate for a brief period at reperfusion decreases cardiac injury. We asked if acidification treatment decreased cardiac injury during reperfusion by inhibiting complex I. Exposure of isolated mouse heart mitochondria to acidic buffer decreased the complex I substrate-stimulated respiration, whereas respiration with complex II substrates was unaltered. Evidence of the rapid and reversible inhibition of complex I by an acidic environment was obtained at the level of isolated complex, intact mitochondria and in situ mitochondria in digitonin-permeabilized cardiac myocytes. Moreover, ischemia-damaged complex I was also reversibly inhibited by an acidic environment. In the buffer-perfused mouse heart, reperfusion with pH 6.6 buffer for the initial 5 min decreased infarction. Compared with untreated hearts, acidification treatment markedly decreased the mitochondrial generation of reactive oxygen species and improved mitochondrial calcium retention capacity and inner mitochondrial membrane integrity. The decrease in infarct size achieved by acidic reperfusion approximates the reduction obtained by a reversible, partial blockade of complex I at reperfusion. Extracellular acidification decreases cardiac injury during reperfusion in part via the transient and reversible inhibition of complex I, leading to a reduction of oxyradical generation accompanied by a decreased susceptibility to mitochondrial permeability transition during early reperfusion.
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Affiliation(s)
- Aijun Xu
- Department of Medicine, Division of Cardiology, Pauley Heart Center, Virginia Commonwealth University School of Medicine, Richmond, Virginia; Department of Anesthesiology, Tongji Hospital, Huazhong University of Science and Technology, Wuhan, China; and
| | - Karol Szczepanek
- Department of Medicine, Division of Cardiology, Pauley Heart Center, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Michael W Maceyka
- Department of Biochemistry and Molecular Biology, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Thomas Ross
- Department of Medicine, Division of Cardiology, Pauley Heart Center, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Elizabeth Bowler
- Department of Medicine, Division of Cardiology, Pauley Heart Center, Virginia Commonwealth University School of Medicine, Richmond, Virginia; University of the West of England, Bristol, United Kingdom
| | - Ying Hu
- Department of Medicine, Division of Cardiology, Pauley Heart Center, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Barrett Kenny
- Department of Medicine, Division of Cardiology, Pauley Heart Center, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Chris Mehfoud
- Department of Medicine, Division of Cardiology, Pauley Heart Center, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Pooja N Desai
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Clive M Baumgarten
- Department of Medicine, Division of Cardiology, Pauley Heart Center, Virginia Commonwealth University School of Medicine, Richmond, Virginia; Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Qun Chen
- Department of Medicine, Division of Cardiology, Pauley Heart Center, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Edward J Lesnefsky
- Department of Medicine, Division of Cardiology, Pauley Heart Center, Virginia Commonwealth University School of Medicine, Richmond, Virginia; Department of Biochemistry and Molecular Biology, Virginia Commonwealth University School of Medicine, Richmond, Virginia; Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, Virginia; McGuire Veterans Affairs Medical Center, Richmond, Virginia;
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Biber J, Murer H, Mohebbi N, Wagner C. Renal Handling of Phosphate and Sulfate. Compr Physiol 2014; 4:771-92. [DOI: 10.1002/cphy.c120031] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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128
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Functional interaction of the cystic fibrosis transmembrane conductance regulator with members of the SLC26 family of anion transporters (SLC26A8 and SLC26A9): physiological and pathophysiological relevance. Int J Biochem Cell Biol 2014; 52:58-67. [PMID: 24530837 DOI: 10.1016/j.biocel.2014.02.001] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Revised: 01/29/2014] [Accepted: 02/01/2014] [Indexed: 12/21/2022]
Abstract
The solute carrier 26 (SLC26) proteins are transmembrane proteins located at the plasma membrane of the cells and transporting a variety of monovalent and divalent anions, including chloride, bicarbonate, sulfate and oxalate. In humans, 11 members have been identified (SLC26A1 to SLC26A11) and although part of them display a very restricted tissue expression pattern, altogether they are widely expressed in the epithelial cells of the body where they contribute to the composition and the pH regulation of the secreted fluids. Importantly, mutations in SLC26A2, A3, A4, and A5 have been associated with distinct human genetic recessive disorders (i.e. diastrophic dysplasia, congenital chloride diarrhea, Pendred syndrome and deafness, respectively), demonstrating their essential and non-redundant functions in many tissues. During the last decade, physical and functional interactions of SLC26 members with the cystic fibrosis transmembrane conductance regulator (CFTR) have been highly documented, leading to the model of a crosstalk based on the binding of the SLC26 STAS domain to the CFTR regulatory domain. In this review, we will focus on the functional interaction of SLC26A8 and SLC26A9 with the CFTR channel. In particular we will highlight the newly published studies indicating that mutations in SLC26A8 and SLC26A9 proteins are associated with a deregulation of the CFTR anion transport activity in the pathophysiological context of the sperm and the pulmonary cells. These studies confirm the physiological relevance of SLC26 and CFTR cross-regulation, opening new gates for the treatment of cystic fibrosis.
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Abstract
Calcium oxalate (CaOx) is the most prevalent type of kidney stone. The amount of oxalate excreted in the urine is a major risk factor for CaOx stone formation. The study by Siener et al. makes a substantial contribution to our understanding of how Oxalobacter formigenes affects oxalate metabolism and excretion in humans and hence influences the risk of developing CaOx kidney stones.
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130
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Hong JH, Park S, Shcheynikov N, Muallem S. Mechanism and synergism in epithelial fluid and electrolyte secretion. Pflugers Arch 2013; 466:1487-99. [PMID: 24240699 DOI: 10.1007/s00424-013-1390-1] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Revised: 10/16/2013] [Accepted: 10/17/2013] [Indexed: 01/04/2023]
Abstract
A central function of epithelia is the control of the volume and electrolyte composition of bodily fluids through vectorial transport of electrolytes and the obligatory H2O. In exocrine glands, fluid and electrolyte secretion is carried out by both acinar and duct cells, with the portion of fluid secreted by each cell type varying among glands. All acinar cells secrete isotonic, plasma-like fluid, while the duct determines the final electrolyte composition of the fluid by absorbing most of the Cl(-) and secreting HCO3 (-). The key transporters mediating acinar fluid and electrolyte secretion are the basolateral Na(+)/K(+) /2Cl(-) cotransporter, the luminal Ca(2+)-activated Cl(-) channel ANO1 and basolateral and luminal Ca(2+)-activated K(+) channels. Ductal fluid and HCO3 (-) secretion are mediated by the basolateral membrane Na(+)-HCO3 (-) cotransporter NBCe1-B and the luminal membrane Cl(-)/HCO3 (-) exchanger slc26a6 and the Cl(-) channel CFTR. The function of the transporters is regulated by multiple inputs, which in the duct include major regulation by the WNK/SPAK pathway that inhibit secretion and the IRBIT/PP1 pathway that antagonize the effects of the WNK/SPAK pathway to both stimulate and coordinate the secretion. The function of these regulatory pathways in secretory glands acinar cells is yet to be examined. An important concept in biology is synergism among signaling pathways to generate the final physiological response that ensures regulation with high fidelity and guards against cell toxicity. While synergism is observed in all epithelial functions, the molecular mechanism mediating the synergism is not known. Recent work reveals a central role for IRBIT as a third messenger that integrates and synergizes the function of the Ca(2+) and cAMP signaling pathways in activation of epithelial fluid and electrolyte secretion. These concepts are discussed in this review using secretion by the pancreatic and salivary gland ducts as model systems.
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Affiliation(s)
- Jeong Hee Hong
- Epithelial Signaling and Transport Section, Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institute of Health, Bethesda, MD, 20892, USA
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Abstract
Chloride transport along the nephron is one of the key actions of the kidney that regulates extracellular volume and blood pressure. To maintain steady state, the kidney needs to reabsorb the vast majority of the filtered load of chloride. This is accomplished by the integrated function of sequential chloride transport activities along the nephron. The detailed mechanisms of transport in each segment generate unique patterns of interactions between chloride and numerous other individual components that are transported by the kidney. Consequently, chloride transport is inextricably intertwined with that of sodium, potassium, protons, calcium, and water. These interactions not only allow for exquisitely precise regulation but also determine the particular patterns in which the system can fail in disease states.
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Affiliation(s)
- John C Edwards
- UNC Kidney Center and the Departments of Medicine and Cell and Molecular Physiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
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132
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Human SLC26A1 gene variants: a pilot study. ScientificWorldJournal 2013; 2013:541710. [PMID: 24250268 PMCID: PMC3819931 DOI: 10.1155/2013/541710] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Accepted: 09/04/2013] [Indexed: 12/12/2022] Open
Abstract
Kidney stones are a global health problem, incurring massive health costs annually. Why stones recur in many patients remains unknown but likely involves environmental, physiological, and genetic factors. The solute linked carrier (SLC) 26A1 gene has previously been linked to kidney stones in mice. SLC26A1 encodes the sulfate anion transporter 1 (SAT1) protein, and its loss in mice leads to hyperoxaluria and calcium oxalate renal stones. To investigate the possible involvement of SAT1 in human urolithiasis, we screened the SLC26A1 gene in a cohort of 13 individuals with recurrent calcium oxalate urolithiasis, which is the commonest type. DNA sequence analyses showed missense mutations in seven patients: one individual was heterozygous R372H; 4 individuals were heterozygous Q556R; one patient was homozygous Q556R; and one patient with severe nephrocalcinosis (requiring nephrectomy) was homozygous Q556R and heterozygous M132T. The M132 amino acid in human SAT1 is conserved with 15 other species and is located within the third transmembrane domain of the predicted SAT1 protein structure, suggesting that this amino acid may be important for SAT1 function. These initial findings demonstrate genetic variants in SLC26A1 of recurrent stone formers and warrant wider independent studies of SLC26A1 in humans with recurrent calcium oxalate stones.
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133
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Soleimani M. SLC26 Cl-/HCO3- exchangers in the kidney: roles in health and disease. Kidney Int 2013; 84:657-66. [PMID: 23636174 PMCID: PMC10947778 DOI: 10.1038/ki.2013.138] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Revised: 01/25/2013] [Accepted: 02/14/2013] [Indexed: 12/30/2022]
Abstract
Solute-linked carrier 26 (SLC26) isoforms constitute a conserved family of anion transporters with 10 distinct members. Except for SLC26A5 (prestin), all can operate as multifunctional anion exchangers, with three members (SLC26A7, SLC26A9, and SLC26A11) also capable of functioning as chloride channels. Several SLC26 isoforms can specifically mediate Cl(-)/HCO(3)(-) exchange. These include SLC26A3, A4, A6, A7, A9, and A11, which are expressed in the kidney except for SLC26A3 (DRA), which is predominantly expressed in the intestine. SLC26 Cl(-)/HCO(3)(-) exchanger isoforms display unique nephron segment distribution patterns with distinct subcellular localization in the kidney tubules. Together with studies in pathophysiologic states and the examination of genetically engineered mouse models, the evolving picture points to important roles for the SLC26 family in health and disease states. This review summarizes recent advances in the characterization of the SLC26 Cl(-)/HCO(3)(-) exchangers in the kidney with emphasis on their essential role in diverse physiological processes, including chloride homeostasis, oxalate excretion and kidney stone formation, vascular volume and blood pressure regulation, and acid-base balance.
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Affiliation(s)
- Manoocher Soleimani
- 1] Center on Genetics of Transport and Epithelial Biology, University of Cincinnati, Cincinnati, Ohio, USA [2] Research Services, Veterans Affairs Medical Center, Cincinnati, Ohio, USA [3] Department of Medicine, University of Cincinnati, Cincinnati, Ohio, USA
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134
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Freel RW, Whittamore JM, Hatch M. Transcellular oxalate and Cl- absorption in mouse intestine is mediated by the DRA anion exchanger Slc26a3, and DRA deletion decreases urinary oxalate. Am J Physiol Gastrointest Liver Physiol 2013; 305:G520-7. [PMID: 23886857 PMCID: PMC3798721 DOI: 10.1152/ajpgi.00167.2013] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Active transcellular oxalate transport in the mammalian intestine contributes to the homeostasis of this important lithogenic anion. Several members of the Slc26a gene family of anion exchangers have a measurable oxalate affinity and are expressed along the gut, apically and basolaterally. Mouse Slc26a6 (PAT1) targets to the apical membrane of enterocytes in the small intestine, and its deletion results in net oxalate absorption and hyperoxaluria. Apical exchangers of the Slc26a family that mediate oxalate absorption have not been established, yet the Slc26a3 [downregulated in adenoma (DRA)] protein is a candidate mediator of oxalate uptake. We evaluated the role of DRA in intestinal oxalate and Cl(-) transport by comparing unidirectional and net ion fluxes across short-circuited segments of small (ileum) and large (cecum and distal colon) intestine from wild-type (WT) and DRA knockout (KO) mice. In WT mice, all segments demonstrated net oxalate and Cl(-) absorption to varying degrees. In KO mice, however, all segments exhibited net anion secretion, which was consistently, and solely, due to a significant reduction in the absorptive unidirectional fluxes. In KO mice, daily urinary oxalate excretion was reduced 66% compared with that in WT mice, while urinary creatinine excretion was unchanged. We conclude that DRA mediates a predominance of the apical uptake of oxalate and Cl(-) absorbed in the small and large intestine of mice under short-circuit conditions. The large reductions in urinary oxalate excretion underscore the importance of transcellular intestinal oxalate absorption, in general, and, more specifically, the importance of the DRA exchanger in oxalate homeostasis.
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Affiliation(s)
- Robert W. Freel
- Department of Pathology, Immunology, and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, Florida
| | - Jonathan M. Whittamore
- Department of Pathology, Immunology, and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, Florida
| | - Marguerite Hatch
- Department of Pathology, Immunology, and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, Florida
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135
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Alper SL, Sharma AK. The SLC26 gene family of anion transporters and channels. Mol Aspects Med 2013; 34:494-515. [PMID: 23506885 DOI: 10.1016/j.mam.2012.07.009] [Citation(s) in RCA: 259] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Accepted: 06/21/2012] [Indexed: 02/08/2023]
Abstract
The phylogenetically ancient SLC26 gene family encodes multifunctional anion exchangers and anion channels transporting a broad range of substrates, including Cl(-), HCO3(-), sulfate, oxalate, I(-), and formate. SLC26 polypeptides are characterized by N-terminal cytoplasmic domains, 10-14 hydrophobic transmembrane spans, and C-terminal cytoplasmic STAS domains, and appear to be homo-oligomeric. SLC26-related SulP proteins of marine bacteria likely transport HCO3(-) as part of oceanic carbon fixation. SulP genes present in antibiotic operons may provide sulfate for antibiotic biosynthetic pathways. SLC26-related Sultr proteins transport sulfate in unicellular eukaryotes and in plants. Mutations in three human SLC26 genes are associated with congenital or early onset Mendelian diseases: chondrodysplasias for SLC26A2, chloride diarrhea for SLC26A3, and deafness with enlargement of the vestibular aqueduct for SLC26A4. Additional disease phenotypes evident only in mouse knockout models include oxalate urolithiasis for Slc26a6 and Slc26a1, non-syndromic deafness for Slc26a5, gastric hypochlorhydria for Slc26a7 and Slc26a9, distal renal tubular acidosis for Slc26a7, and male infertility for Slc26a8. STAS domains are required for cell surface expression of SLC26 proteins, and contribute to regulation of the cystic fibrosis transmembrane regulator in complex, cell- and tissue-specific ways. The protein interactomes of SLC26 polypeptides are under active investigation.
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Affiliation(s)
- Seth L Alper
- Renal Division and Division of Molecular and Vascular Medicine, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA.
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137
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Ohana E, Shcheynikov N, Moe OW, Muallem S. SLC26A6 and NaDC-1 transporters interact to regulate oxalate and citrate homeostasis. J Am Soc Nephrol 2013; 24:1617-26. [PMID: 23833257 DOI: 10.1681/asn.2013010080] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The combination of hyperoxaluria and hypocitraturia can trigger Ca(2+)-oxalate stone formation, even in the absence of hypercalciuria, but the molecular mechanisms that control urinary oxalate and citrate levels are not understood completely. Here, we examined the relationship between the oxalate transporter SLC26A6 and the citrate transporter NaDC-1 in citrate and oxalate homeostasis. Compared with wild-type mice, Slc26a6-null mice exhibited increased renal and intestinal sodium-dependent succinate uptake, as well as urinary hyperoxaluria and hypocitraturia, but no change in urinary pH, indicating enhanced transport activity of NaDC-1. When co-expressed in Xenopus oocytes, NaDC-1 enhanced Slc26a6 transport activity. In contrast, Slc26a6 inhibited NaDC-1 transport activity in an activity dependent manner to restricted tubular citrate absorption. Biochemical and physiologic analysis revealed that the STAS domain of Slc26a6 and the first intracellular loop of NaDC-1 mediated both the physical and functional interactions of these transporters. These findings reveal a molecular pathway that senses and tightly regulates oxalate and citrate levels and may control Ca(2+)-oxalate stone formation.
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Affiliation(s)
- Ehud Ohana
- Epithelial Signaling and Transport Section, Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland, and
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138
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Amin R, Sharma S, Ratakonda S, Hassan HA. Extracellular nucleotides inhibit oxalate transport by human intestinal Caco-2-BBe cells through PKC-δ activation. Am J Physiol Cell Physiol 2013; 305:C78-89. [PMID: 23596171 DOI: 10.1152/ajpcell.00339.2012] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Nephrolithiasis remains a major health problem in Western countries. Seventy to 80% of kidney stones are composed of calcium oxalate, and small changes in urinary oxalate affect risk of kidney stone formation. Intestinal oxalate secretion mediated by the anion exchanger SLC26A6 plays an essential role in preventing hyperoxaluria and calcium oxalate nephrolithiasis, indicating that understanding the mechanisms regulating intestinal oxalate transport is critical for management of hyperoxaluria. Purinergic signaling modulates several intestinal processes through pathways including PKC activation, which we previously found to inhibit Slc26a6 activity in mouse duodenal tissue. We therefore examined whether purinergic stimulation with ATP and UTP affects oxalate transport by human intestinal Caco-2-BBe (C2) cells. We measured [¹⁴C]oxalate uptake in the presence of an outward Cl⁻ gradient as an assay of Cl⁻/oxalate exchange activity, ≥50% of which is mediated by SLC26A6. We found that ATP and UTP significantly inhibited oxalate transport by C2 cells, an effect blocked by the PKC inhibitor Gö-6983. Utilizing pharmacological agonists and antagonists, as well as PKC-δ knockdown studies, we observed that ATP inhibits oxalate transport through the P2Y₂ receptor, PLC, and PKC-δ. Biotinylation studies showed that ATP inhibits oxalate transport by lowering SLC26A6 surface expression. These findings are of potential relevance to pathophysiology of inflammatory bowel disease-associated hyperoxaluria, where supraphysiological levels of ATP/UTP are expected and overexpression of the P2Y₂ receptor has been reported. We conclude that ATP and UTP inhibit oxalate transport by lowering SLC26A6 surface expression in C2 cells through signaling pathways including the P2Y₂ purinergic receptor, PLC, and PKC-δ.
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Affiliation(s)
- Ruhul Amin
- Department of Medicine, University of Chicago, Chicago, IL 60637, USA
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Becknell B, Carpenter AR, Bolon B, Asplin JR, Ingraham SE, Hains DS, Schwaderer AL, McHugh KM. Struvite urolithiasis and chronic urinary tract infection in a murine model of urinary diversion. Urology 2013; 81:943-8. [PMID: 23523293 DOI: 10.1016/j.urology.2013.02.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Revised: 01/17/2013] [Accepted: 02/01/2013] [Indexed: 11/27/2022]
Abstract
OBJECTIVE To characterize the clinical course after cutaneous vesicostomy (CV) in megabladder (mgb(-/-)) mice with functional urinary bladder obstruction. MATERIALS AND METHODS A total of 45 mgb(-/-) male mice underwent CV at a median age of 25 days. The 34 mice that survived >3 days after CV were evaluated by serial observation and renal ultrasonography. The moribund mice were killed. The urinary bladders and kidneys were analyzed by histopathologic analysis, and urine biochemical studies were performed. RESULTS At a median duration of 11 weeks after CV, 35% of mgb(-/-) male mice (12 of 34) had become moribund with pelvic masses, which were identified as bladder stones at necropsy. The urine pH was alkaline, and microscopic examination demonstrated struvite crystals. The urine samples contained Gram-positive cocci, and the urine cultures were polymicrobial. The stone composition was chiefly struvite (88%-94%) admixed with calcium phosphate. In 40% of cases (2 of 5), retained intravesical polypropylene suture was identified as the presumed nidus. No stones were detected in >100 male mice before CV or in 25 cases when CV was performed using polydioxanone suture. The kidneys from 33% of the mice (4/12) with bladder stones contained staghorn calculi. The histopathologic findings from the mice with struvite stones demonstrated active cystitis, pyelitis, and chronic pyelonephritis. CONCLUSION These findings attest to the importance of the nidus in lithogenesis and provide a novel murine model for struvite urolithiasis and chronic infection of the diverted urinary tract.
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Affiliation(s)
- Brian Becknell
- Division of Nephrology, Department of Pediatrics, Nationwide Children's Hospital, Columbus, OH 43205, USA.
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140
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Poesen R, Meijers B, Evenepoel P. The colon: an overlooked site for therapeutics in dialysis patients. Semin Dial 2013; 26:323-32. [PMID: 23458264 DOI: 10.1111/sdi.12082] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Morbidity and mortality related to chronic kidney disease remain unacceptably high, despite tremendous progress in its prevention and treatment. In an ongoing quest to improve outcome in chronic kidney disease patients, the colon might be an appealing, but largely underexplored, therapeutic target. A clear bi-directional functional relationship exists between the colon and kidney, also referred as to the colo-renal axis. Uremia has an important impact on the colonic microbiome. The microbiome, in turn, is an important source of uremic toxins, with p-cresyl sulfate and indoxyl sulfate as important prototypes. These co-metabolites accumulate in the face of a falling kidney function, and may accelerate the progression of renal and cardiovascular disease. Several therapeutic interventions, including prebiotics and adsorbants, specifically target these colon-derived uremic toxins originating from bacterial metabolism. As kidney function declines, the colon also gains importance in the homeostasis and disposal of potassium and oxalate. Their colonic secretion may be increased by drugs increasing the expression of cAMP and by probiotics (e.g., Oxalobacter formigenes).
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Affiliation(s)
- Ruben Poesen
- Division of Nephrology, Department of Microbiology and Immunology, University Hospitals Leuven, Leuven, Belgium
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141
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Robijn S, Vervaet BA, Hoppe B, D'Haese PC, Verhulst A. Lanthanum carbonate inhibits intestinal oxalate absorption and prevents nephrocalcinosis after oxalate loading in rats. J Urol 2012; 189:1960-6. [PMID: 23228382 DOI: 10.1016/j.juro.2012.12.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Accepted: 12/05/2012] [Indexed: 01/16/2023]
Abstract
PURPOSE Increased intestinal oxalate absorption leads to increased urinary oxalate excretion (secondary hyperoxaluria) and calcium oxalate crystal formation, contributing to nephrocalcinosis/lithiasis. Lanthanum carbonate is an intestinal phosphate binder that is orally administered to patients on dialysis to treat hyperphosphatemia. It is hypothesized that lanthanum can also bind oxalate, in addition to phosphate. We evaluated this in vitro and in vivo. MATERIALS AND METHODS In vitro oxalate binding was evaluated by oxalate precipitation from a solution by lanthanum. In vivo oxalate absorption kinetics and the effect of lanthanum carbonate on nephrocalcinosis development were assessed in male Sprague-Dawley® rats that received 1) 1,000 mg lanthanum carbonate and oxalate, 2) carboxymethylcellulose and oxalate or 3) carboxymethylcellulose by gavage for up to 12 hours (kinetics) or 7 days (nephrocalcinosis). Plasma and urinary oxalate concentrations were measured at several time points after gavage. The degree of nephrocalcinosis was assessed histomorphometrically on von Kossa stained sections and by measuring total calcium content in renal tissue. RESULTS In vitro lanthanum bound oxalate in a pH range comparable to the range of the intestine. In vivo oxalate administration in untreated animals resulted in a biphasic pattern of increased plasma oxalate levels, which was almost abolished in lanthanum treated rats. In the urine of treated rats oxaluria and calcium oxalate crystalluria were blunted. Moreover, significantly decreased nephrocalcinosis was observed compared with that in untreated rats. CONCLUSIONS Lanthanum carbonate is a promising agent for the future prevention/treatment of secondary hyperoxaluria.
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Affiliation(s)
- Stef Robijn
- Laboratory of Pathophysiology, Faculty of Pharmaceutical, Biomedical and Veterinary Sciences, University of Antwerp, Antwerp, Belgium
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142
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Hirata T, Cabrero P, Berkholz DS, Bondeson DP, Ritman EL, Thompson JR, Dow JAT, Romero MF. In vivo Drosophilia genetic model for calcium oxalate nephrolithiasis. Am J Physiol Renal Physiol 2012; 303:F1555-62. [PMID: 22993075 DOI: 10.1152/ajprenal.00074.2012] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Nephrolithiasis is a major public health problem with a complex and varied etiology. Most stones are composed of calcium oxalate (CaOx), with dietary excess a risk factor. Because of complexity of mammalian system, the details of stone formation remain to be understood. Here we have developed a nephrolithiasis model using the genetic model Drosophila melanogaster, which has a simple, transparent kidney tubule. Drosophilia reliably develops CaOx stones upon dietary oxalate supplementation, and the nucleation and growth of microliths can be viewed in real time. The Slc26 anion transporter dPrestin (Slc26a5/6) is strongly expressed in Drosophilia kidney, and biophysical analysis shows that it is a potent oxalate transporter. When dPrestin is knocked down by RNAi in fly kidney, formation of microliths is reduced, identifying dPrestin as a key player in oxalate excretion. CaOx stone formation is an ancient conserved process across >400 My of divergent evolution (fly and human), and from this study we can conclude that the fly is a good genetic model of nephrolithiasis.
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Affiliation(s)
- Taku Hirata
- Dept. Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, MN 55905, USA
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143
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Assimos D. Re: Slc13a1 and Slc26a1 KO Models Reveal Physiological Roles of Anion Transporters. J Urol 2012; 188:1044. [DOI: 10.1016/j.juro.2012.05.038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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144
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Feng L, Li H, Li X, Chen L, Shen Z, Guan Y. Colorimetric sensing of anions in water using ratiometric indicator-displacement assay. Anal Chim Acta 2012; 743:1-8. [DOI: 10.1016/j.aca.2012.06.041] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2012] [Revised: 06/12/2012] [Accepted: 06/19/2012] [Indexed: 10/28/2022]
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145
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Garcia-Perez I, Villaseñor A, Wijeyesekera A, Posma JM, Jiang Z, Stamler J, Aronson P, Unwin R, Barbas C, Elliott P, Nicholson J, Holmes E. Urinary metabolic phenotyping the slc26a6 (chloride-oxalate exchanger) null mouse model. J Proteome Res 2012; 11:4425-35. [PMID: 22594923 DOI: 10.1021/pr2012544] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The prevalence of renal stone disease is increasing, although it remains higher in men than in women when matched for age. While still somewhat controversial, several studies have reported an association between renal stone disease and hypertension, but this may be confounded by a shared link with obesity. However, independent of obesity, hyperoxaluria has been shown to be associated with hypertension in stone-formers, and the most common type of renal stone is composed of calcium oxalate. The chloride-oxalate exchanger slc26a6 (also known as CFEX or PAT-1), located in the renal proximal tubule, was originally thought to have an important role in sodium homeostasis and thereby blood pressure control, but it has recently been shown to have a key function in oxalate balance by mediating oxalate secretion in the gut. We have applied two orthogonal analytical platforms (NMR spectroscopy and capillary electrophoresis with UV detection) in parallel to characterize the urinary metabolic signatures related to the loss of the renal chloride-oxalate exchanger in slc26a6 null mice. Clear metabolic differentiation between the urinary profiles of the slc26a6 null and the wild type mice were observed using both methods, with the combination of NMR and CE-UV providing extensive coverage of the urinary metabolome. Key discriminating metabolites included oxalate, m-hydroxyphenylpropionylsulfate (m-HPPS), trimethylamine-N-oxide, glycolate and scyllo-inositol (higher in slc26a6 null mice) and hippurate, taurine, trimethylamine, and citrate (lower in slc26a6 null mice). In addition to the reduced efficiency of anion transport, several of these metabolites (hippurate, m-HPPS, methylamines) reflect alteration in gut microbial cometabolic activities. Gender-related metabotypes were also observed in both wild type and slc26a6 null groups. Urinary metabolites that showed a sex-specific pattern included trimethylamine, trimethylamine-N-oxide, citrate, spermidine, guanidinoacetate, and 2-oxoisocaproate. The gender-dependent metabolic expression of the consequences of slc26a6 deletion might have relevance to the difference in prevalence of renal stone formation in men and women. The different composition of microbial metabolites in the slc26a6 null mice is consistent with the fact that the slc26a6 transporter is found in a range of tissues, including the kidney and intestine, and provides further evidence for the "long reach" of the microbiota in physiological and pathological processes.
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Affiliation(s)
- Isabel Garcia-Perez
- Biomolecular Medicine, Department of Surgery and Cancer, Faculty of Medicine, Imperial College London, SW7 2AZ London, UK
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146
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Capolongo G, Abul-Ezz S, Moe OW, Sakhaee K. Subclinical celiac disease and crystal-induced kidney disease following kidney transplant. Am J Kidney Dis 2012; 60:662-7. [PMID: 22739230 DOI: 10.1053/j.ajkd.2012.02.342] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Accepted: 02/29/2012] [Indexed: 11/11/2022]
Abstract
Decreased kidney function from kidney deposition of calcium oxalate has been described previously in inflammatory bowel disease and after jejuno-ileal and Roux-en-Y gastric bypass surgeries. Although celiac disease is the most prevalent bowel abnormality associated with intestinal malabsorption, its relationship to high kidney oxalate burden and decreased kidney function has not been established. We report a case of subclinical celiac disease and hyperoxaluria that presented with loss of kidney function as a result of high oxalate load in the absence of overt diarrhea, documented intestinal fat malabsorption, and nephrolithiasis. Subclinical celiac disease is commonly overlooked and hyperoxaluria is not usually investigated in kidney patients. We propose that this entity should be suspected in patients with chronic kidney disease in which the cause of kidney damage has not been clearly established.
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Affiliation(s)
- Giovanna Capolongo
- Charles & Jane Pak Center for Mineral Metabolism & Clinical Research, University of Texas Southwestern Medical Center, Dallas, USA
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147
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Sakhaee K, Maalouf NM, Sinnott B. Clinical review. Kidney stones 2012: pathogenesis, diagnosis, and management. J Clin Endocrinol Metab 2012; 97:1847-60. [PMID: 22466339 PMCID: PMC3387413 DOI: 10.1210/jc.2011-3492] [Citation(s) in RCA: 145] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
CONTEXT The pathogenetic mechanisms of kidney stone formation are complex and involve both metabolic and environmental risk factors. Over the past decade, major advances have been made in the understanding of the pathogenesis, diagnosis, and treatment of kidney stone disease. EVIDENCE ACQUISITION AND SYNTHESIS Both original and review articles were found via PubMed search reporting on pathophysiology, diagnosis, and management of kidney stones. These resources were integrated with the authors' knowledge of the field. CONCLUSION Nephrolithiasis remains a major economic and health burden worldwide. Nephrolithiasis is considered a systemic disorder associated with chronic kidney disease, bone loss and fractures, increased risk of coronary artery disease, hypertension, type 2 diabetes mellitus, and the metabolic syndrome. Further understanding of the pathophysiological link between nephrolithiasis and these systemic disorders is necessary for the development of new therapeutic options.
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Affiliation(s)
- Khashayar Sakhaee
- Department of Internal Medicine, Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA.
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148
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Markovich D. Slc13a1 and Slc26a1 KO models reveal physiological roles of anion transporters. Physiology (Bethesda) 2012; 27:7-14. [PMID: 22311966 DOI: 10.1152/physiol.00041.2011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Anion transporters NaS1 (SLC13A1) and Sat1 (SLC26A1) mediate sulfate (re)absorption across renal proximal tubule and small intestinal epithelia, thereby regulating blood sulfate levels. Disruption of murine NaS1 and Sat1 genes leads to hyposulfatemia and hypersulfaturia. Sat1-null mice also exhibit hyperoxalemia, hyperoxaluria, and calcium oxalate urolithiasis. This review will highlight the current pathophysiological features of NaS1- and Sat1-null mice resulting from alterations in circulating sulfate and oxalate anion levels.
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Affiliation(s)
- Daniel Markovich
- Molecular Physiology Group, School of Biomedical Sciences, University of Queensland, St. Lucia, Australia.
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149
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Ko N, Knauf F, Jiang Z, Markovich D, Aronson PS. Sat1 is dispensable for active oxalate secretion in mouse duodenum. Am J Physiol Cell Physiol 2012; 303:C52-7. [PMID: 22517357 DOI: 10.1152/ajpcell.00385.2011] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Mice deficient for the apical membrane oxalate transporter SLC26A6 develop hyperoxalemia, hyperoxaluria, and calcium oxalate stones due to a defect in intestinal oxalate secretion. However, the nature of the basolateral membrane oxalate transport process that operates in series with SLC26A6 to mediate active oxalate secretion in the intestine remains unknown. Sulfate anion transporter-1 (Sat1 or SLC26A1) is a basolateral membrane anion exchanger that mediates intestinal oxalate transport. Moreover, Sat1-deficient mice also have a phenotype of hyperoxalemia, hyperoxaluria, and calcium oxalate stones. We, therefore, tested the role of Sat1 in mouse duodenum, a tissue with Sat1 expression and SLC26A6-dependent oxalate secretion. Although the active secretory flux of oxalate across mouse duodenum was strongly inhibited (>90%) by addition of the disulfonic stilbene DIDS to the basolateral solution, secretion was unaffected by changes in medium concentrations of sulfate and bicarbonate, key substrates for Sat1-mediated anion exchange. Inhibition of intracellular bicarbonate production by acetazolamide and complete removal of bicarbonate from the buffer also produced no change in oxalate secretion. Finally, active oxalate secretion was not reduced in Sat1-null mice. We conclude that a DIDS-sensitive basolateral transporter is involved in mediating oxalate secretion across mouse duodenum, but Sat1 itself is dispensable for this process.
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Affiliation(s)
- Narae Ko
- Section of Nephrology, Dept. of Internal Medicine, Yale School of Medicine, New Haven, CT 06520-8029, USA
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150
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Hirata T, Czapar A, Brin LR, Haritonova A, Bondeson DP, Linser PJ, Cabrero P, Dow JAT, Romero MF. Ion and solute transport by Prestin in Drosophila and Anopheles. JOURNAL OF INSECT PHYSIOLOGY 2012; 58:563-569. [PMID: 22321763 PMCID: PMC3482613 DOI: 10.1016/j.jinsphys.2012.01.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2011] [Revised: 01/11/2012] [Accepted: 01/14/2012] [Indexed: 05/31/2023]
Abstract
The gut and Malpighian tubules of insects are the primary sites of active solute and water transport for controlling hemolymph and urine composition, pH, and osmolarity. These processes depend on ATPase (pumps), channels and solute carriers (Slc proteins). Maturation of genomic databases enables us to identify the putative molecular players for these processes. Anion transporters of the Slc4 family, AE1 and NDAE1, have been reported as HCO(3)(-) transporters, but are only part of the story. Here we report Dipteran (Drosophila melanogaster (d) and Anopheles gambiae (Ag)) anion exchangers, belonging to the Slc26 family, which are multi-functional anion exchangers. One Drosophila and two Ag homologues of mammalian Slc26a5 (Prestin) and Slc26a6 (aka, PAT1, CFEX) were identified and designated dPrestin, AgPrestinA and AgPrestinB. dPrestin and AgPrestinB show electrogenic anion exchange (Cl(-)/nHCO(3)(-), Cl(-)/SO(4)(2-) and Cl(-)/oxalate(2-)) in an oocyte expression system. Since these transporters are the only Dipteran Slc26 proteins whose transport is similar to mammalian Slc26a6, we submit that Dipteran Prestin are functional and even molecular orthologues of mammalian Slc26a6. OSR1 kinase increases dPrestin ion transport, implying another set of physiological processes controlled by WNK/SPAK signaling in epithelia. All of these mRNAs are highly expressed in the gut and Malpighian tubules. Dipteran Prestin proteins appear suited for central roles in bicarbonate, sulfate and oxalate metabolism including generating the high pH conditions measured in the Dipteran midgut lumen. Finally, we present and discuss Drosophila genetic models that integrate these processes.
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Affiliation(s)
- Taku Hirata
- Physiology & Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, MN 55905 USA
- Mayo Clinic O’Brien Urology Research Center, Mayo Clinic College of Medicine, Rochester, MN 55905 USA
| | - Anna Czapar
- Physiology & Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, MN 55905 USA
| | - Lauren R. Brin
- Physiology & Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, MN 55905 USA
- Biochemistry & Molecular Biology, Mayo Clinic College of Medicine, Rochester, MN 55905 USA
| | - Alyona Haritonova
- Physiology & Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, MN 55905 USA
| | - Daniel P. Bondeson
- Physiology & Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, MN 55905 USA
- Biochemistry & Molecular Biology, Mayo Clinic College of Medicine, Rochester, MN 55905 USA
- Mayo Clinic O’Brien Urology Research Center, Mayo Clinic College of Medicine, Rochester, MN 55905 USA
| | - Paul J. Linser
- University of Florida Whitney Laboratory, 9505 Ocean Shore Blvd., St. Augustine FL, 32086
| | - Pablo Cabrero
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Julian A. T. Dow
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
- Clinical Laboratory Sciences, College of Applied Medical Sciences, King Saud University, Riyadh, KSA
| | - Michael F. Romero
- Physiology & Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, MN 55905 USA
- Mayo Clinic O’Brien Urology Research Center, Mayo Clinic College of Medicine, Rochester, MN 55905 USA
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