1
|
Andrini O, Eladari D, Picard N. ClC-K Kidney Chloride Channels: From Structure to Pathology. Handb Exp Pharmacol 2024; 283:35-58. [PMID: 36811727 DOI: 10.1007/164_2023_635] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
The molecular basis of chloride transport varies all along the nephron depending on the tubular segments especially in the apical entry of the cell. The major chloride exit pathway during reabsorption is provided by two kidney-specific ClC chloride channels ClC-Ka and ClC-Kb (encoded by CLCNKA and CLCNKB gene, respectively) corresponding to rodent ClC-K1 and ClC-K2 (encoded by Clcnk1 and Clcnk2). These channels function as dimers and their trafficking to the plasma membrane requires the ancillary protein Barttin (encoded by BSND gene). Genetic inactivating variants of the aforementioned genes lead to renal salt-losing nephropathies with or without deafness highlighting the crucial role of ClC-Ka, ClC-Kb, and Barttin in the renal and inner ear chloride handling. The purpose of this chapter is to summarize the latest knowledge on renal chloride structure peculiarity and to provide some insight on the functional expression on the segments of the nephrons and on the related pathological effects.
Collapse
Affiliation(s)
- Olga Andrini
- Univ Lyon, University Claude Bernard Lyon 1, CNRS UMR 5284, INSERM U 1314, Melis, Lyon, France.
| | - Dominique Eladari
- CHU Amiens Picardie, Service de Médecine de Précision des maladies Métaboliques et Rénales, Université de Picardie Jules Verne, Amiens, France
| | - Nicolas Picard
- CNRS, LBTI UMR5305, Université Claude Bernard Lyon 1, Lyon, France
| |
Collapse
|
2
|
van der Wijst J, Belge H, Bindels RJM, Devuyst O. Learning Physiology From Inherited Kidney Disorders. Physiol Rev 2019; 99:1575-1653. [PMID: 31215303 DOI: 10.1152/physrev.00008.2018] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The identification of genes causing inherited kidney diseases yielded crucial insights in the molecular basis of disease and improved our understanding of physiological processes that operate in the kidney. Monogenic kidney disorders are caused by mutations in genes coding for a large variety of proteins including receptors, channels and transporters, enzymes, transcription factors, and structural components, operating in specialized cell types that perform highly regulated homeostatic functions. Common variants in some of these genes are also associated with complex traits, as evidenced by genome-wide association studies in the general population. In this review, we discuss how the molecular genetics of inherited disorders affecting different tubular segments of the nephron improved our understanding of various transport processes and of their involvement in homeostasis, while providing novel therapeutic targets. These include inherited disorders causing a dysfunction of the proximal tubule (renal Fanconi syndrome), with emphasis on epithelial differentiation and receptor-mediated endocytosis, or affecting the reabsorption of glucose, the handling of uric acid, and the reabsorption of sodium, calcium, and magnesium along the kidney tubule.
Collapse
Affiliation(s)
- Jenny van der Wijst
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center , Nijmegen , The Netherlands ; Institute of Physiology, University of Zurich , Zurich , Switzerland ; and Division of Nephrology, Institute of Experimental and Clinical Research (IREC), Medical School, Université catholique de Louvain, Brussels, Belgium
| | - Hendrica Belge
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center , Nijmegen , The Netherlands ; Institute of Physiology, University of Zurich , Zurich , Switzerland ; and Division of Nephrology, Institute of Experimental and Clinical Research (IREC), Medical School, Université catholique de Louvain, Brussels, Belgium
| | - René J M Bindels
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center , Nijmegen , The Netherlands ; Institute of Physiology, University of Zurich , Zurich , Switzerland ; and Division of Nephrology, Institute of Experimental and Clinical Research (IREC), Medical School, Université catholique de Louvain, Brussels, Belgium
| | - Olivier Devuyst
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center , Nijmegen , The Netherlands ; Institute of Physiology, University of Zurich , Zurich , Switzerland ; and Division of Nephrology, Institute of Experimental and Clinical Research (IREC), Medical School, Université catholique de Louvain, Brussels, Belgium
| |
Collapse
|
3
|
García Castaño A, Pérez de Nanclares G, Madariaga L, Aguirre M, Madrid Á, Chocrón S, Nadal I, Navarro M, Lucas E, Fijo J, Espino M, Espitaletta Z, García Nieto V, Barajas de Frutos D, Loza R, Pintos G, Castaño L, Ariceta G. Poor phenotype-genotype association in a large series of patients with Type III Bartter syndrome. PLoS One 2017; 12:e0173581. [PMID: 28288174 PMCID: PMC5348002 DOI: 10.1371/journal.pone.0173581] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Accepted: 02/22/2017] [Indexed: 12/19/2022] Open
Abstract
Introduction Type III Bartter syndrome (BS) is an autosomal recessive renal tubule disorder caused by loss-of-function mutations in the CLCNKB gene, which encodes the chloride channel protein ClC-Kb. In this study, we carried out a complete clinical and genetic characterization in a cohort of 30 patients, one of the largest series described. By comparing with other published populations, and considering that 80% of our patients presented the p.Ala204Thr Spanish founder mutation presumably associated with a common phenotype, we aimed to test the hypothesis that allelic differences could explain the wide phenotypic variability observed in patients with type III BS. Methods Clinical data were retrieved from the referral centers. The exon regions and flanking intronic sequences of the CLCNKB gene were screened for mutations by polymerase chain reaction (PCR) followed by direct Sanger sequencing. Presence of gross deletions or duplications in the region was checked for by MLPA and QMPSF analyses. Results Polyuria, polydipsia and dehydration were the main common symptoms. Metabolic alkalosis and hypokalemia of renal origin were detected in all patients at diagnosis. Calciuria levels were variable: hypercalciuria was detected in 31% of patients, while 23% had hypocalciuria. Nephrocalcinosis was diagnosed in 20% of the cohort. Two novel CLCNKB mutations were identified: a small homozygous deletion (c.753delG) in one patient and a small deletion (c.1026delC) in another. The latter was present in compound heterozygosis with the already previously described p.Glu442Gly mutation. No phenotypic association was obtained regarding the genotype. Conclusion A poor correlation was found between a specific type of mutation in the CLCNKB gene and type III BS phenotype. Importantly, two CLCNKB mutations not previously described were found in our cohort.
Collapse
Affiliation(s)
| | | | - Leire Madariaga
- Pediatric Nephrology, Cruces University Hospital, Bizkaia, Spain
- Department of Pediatrics, School of Medicine and Odontology, University of Basque Country UPV/EHU, Bizkaia, Spain
| | - Mireia Aguirre
- Pediatric Nephrology, Cruces University Hospital, Bizkaia, Spain
| | - Álvaro Madrid
- Pediatric Nephrology, Vall d’Hebron University Hospital, Universitat Autonoma, Barcelona, Spain
| | - Sara Chocrón
- Pediatric Nephrology, Vall d’Hebron University Hospital, Universitat Autonoma, Barcelona, Spain
| | - Inmaculada Nadal
- Pediatric Nephrology, Virgen del Camino Hospital, Pamplona, Spain
| | | | - Elena Lucas
- Pediatrics, Manises Hospital, Valencia, Spain
| | - Julia Fijo
- Pediatric Nephrology, Virgen del Rocío Hospital, Sevilla, Spain
| | - Mar Espino
- Pediatric Nephrology, Fundación Alcorcón University Hospital, Madrid, Spain
| | | | - Víctor García Nieto
- Pediatric Nephrology, Nuestra Señora de Candelaria University Hospital, Tenerife, Canarias, Spain
| | | | - Reyner Loza
- Nephrology Unit, Cayetano Heredia University, Cayetano Heredia Hospital, Lima, Peru
| | - Guillem Pintos
- Germans Trias i Pujol University Hospital, Badalona, Spain
| | - Luis Castaño
- BioCruces Health Research Institute, Ciberer, Cruces University Hospital, Bizkaia, Spain
- Department of Pediatrics, School of Medicine and Odontology, University of Basque Country UPV/EHU, Bizkaia, Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Instituto de Salud Carlos III, Madrid, Spain
| | - RenalTube Group
- BioCruces Health Research Institute, Ciberer, Cruces University Hospital, Bizkaia, Spain
- Pediatric Nephrology, Vall d’Hebron University Hospital, Universitat Autonoma, Barcelona, Spain
- Pediatric Nephrology, Nuestra Señora de Candelaria University Hospital, Tenerife, Canarias, Spain
- Pediatric Nephrology, Asturias Central University Hospital, Oviedo, Asturias, Spain
| | - Gema Ariceta
- Pediatric Nephrology, Vall d’Hebron University Hospital, Universitat Autonoma, Barcelona, Spain
- * E-mail:
| |
Collapse
|
4
|
Andrini O, Keck M, Briones R, Lourdel S, Vargas-Poussou R, Teulon J. ClC-K chloride channels: emerging pathophysiology of Bartter syndrome type 3. Am J Physiol Renal Physiol 2015; 308:F1324-34. [DOI: 10.1152/ajprenal.00004.2015] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Accepted: 03/23/2015] [Indexed: 02/08/2023] Open
Abstract
The mutations in the CLCNKB gene encoding the ClC-Kb chloride channel are responsible for Bartter syndrome type 3, one of the four variants of Bartter syndrome in the genetically based nomenclature. All forms of Bartter syndrome are characterized by hypokalemia, metabolic alkalosis, and secondary hyperaldosteronism, but Bartter syndrome type 3 has the most heterogeneous presentation, extending from severe to very mild. A relatively large number of CLCNKB mutations have been reported, including gene deletions and nonsense or missense mutations. However, only 20 CLCNKB mutations have been functionally analyzed, due to technical difficulties regarding ClC-Kb functional expression in heterologous systems. This review provides an overview of recent progress in the functional consequences of CLCNKB mutations on ClC-Kb chloride channel activity. It has been observed that 1) all ClC-Kb mutants have an impaired expression at the membrane; and 2) a minority of the mutants combines reduced membrane expression with altered pH-dependent channel gating. Although further investigation is needed to fully characterize disease pathogenesis, Bartter syndrome type 3 probably belongs to the large family of conformational diseases, in which the mutations destabilize channel structure, inducing ClC-Kb retention in the endoplasmic reticulum and accelerated channel degradation.
Collapse
Affiliation(s)
- Olga Andrini
- UPMC Université Paris 06, UMR_S 1138, Team 3, Paris, France
- INSERM, UMR_S 872, Paris, France
| | - Mathilde Keck
- UPMC Université Paris 06, UMR_S 1138, Team 3, Paris, France
- INSERM, UMR_S 872, Paris, France
| | - Rodolfo Briones
- Department of Theoretical and Computational Biophysics, Max-Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Stéphane Lourdel
- UPMC Université Paris 06, UMR_S 1138, Team 3, Paris, France
- INSERM, UMR_S 872, Paris, France
| | - Rosa Vargas-Poussou
- Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Département de Génétique, Paris, France; and
- Université Paris-Descartes, Faculté de Médecine, Paris, France
| | - Jacques Teulon
- UPMC Université Paris 06, UMR_S 1138, Team 3, Paris, France
- INSERM, UMR_S 872, Paris, France
| |
Collapse
|
5
|
Stauber T, Weinert S, Jentsch TJ. Cell biology and physiology of CLC chloride channels and transporters. Compr Physiol 2013; 2:1701-44. [PMID: 23723021 DOI: 10.1002/cphy.c110038] [Citation(s) in RCA: 112] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Proteins of the CLC gene family assemble to homo- or sometimes heterodimers and either function as Cl(-) channels or as Cl(-)/H(+)-exchangers. CLC proteins are present in all phyla. Detailed structural information is available from crystal structures of bacterial and algal CLCs. Mammals express nine CLC genes, four of which encode Cl(-) channels and five 2Cl(-)/H(+)-exchangers. Two accessory β-subunits are known: (1) barttin and (2) Ostm1. ClC-Ka and ClC-Kb Cl(-) channels need barttin, whereas Ostm1 is required for the function of the lysosomal ClC-7 2Cl(-)/H(+)-exchanger. ClC-1, -2, -Ka and -Kb Cl(-) channels reside in the plasma membrane and function in the control of electrical excitability of muscles or neurons, in extra- and intracellular ion homeostasis, and in transepithelial transport. The mainly endosomal/lysosomal Cl(-)/H(+)-exchangers ClC-3 to ClC-7 may facilitate vesicular acidification by shunting currents of proton pumps and increase vesicular Cl(-) concentration. ClC-3 is also present on synaptic vesicles, whereas ClC-4 and -5 can reach the plasma membrane to some extent. ClC-7/Ostm1 is coinserted with the vesicular H(+)-ATPase into the acid-secreting ruffled border membrane of osteoclasts. Mice or humans lacking ClC-7 or Ostm1 display osteopetrosis and lysosomal storage disease. Disruption of the endosomal ClC-5 Cl(-)/H(+)-exchanger leads to proteinuria and Dent's disease. Mouse models in which ClC-5 or ClC-7 is converted to uncoupled Cl(-) conductors suggest an important role of vesicular Cl(-) accumulation in these pathologies. The important functions of CLC Cl(-) channels were also revealed by human diseases and mouse models, with phenotypes including myotonia, renal loss of salt and water, deafness, blindness, leukodystrophy, and male infertility.
Collapse
Affiliation(s)
- Tobias Stauber
- Leibniz-Institut für Molekulare Pharmakologie FMP and Max-Delbrück-Centrum für Molekulare Medizin MDC, Berlin, Germany
| | | | | |
Collapse
|
6
|
García Castaño A, Pérez de Nanclares G, Madariaga L, Aguirre M, Madrid A, Nadal I, Navarro M, Lucas E, Fijo J, Espino M, Espitaletta Z, Castaño L, Ariceta G. Genetics of type III Bartter syndrome in Spain, proposed diagnostic algorithm. PLoS One 2013; 8:e74673. [PMID: 24058621 PMCID: PMC3776854 DOI: 10.1371/journal.pone.0074673] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Accepted: 08/05/2013] [Indexed: 11/21/2022] Open
Abstract
The p.Ala204Thr mutation (exon 7) of the CLCNKB gene is a "founder" mutation that causes most of type III Bartter syndrome cases in Spain. We performed genetic analysis of the CLCNKB gene, which encodes for the chloride channel protein ClC-Kb, in a cohort of 26 affected patients from 23 families. The diagnostic algorithm was: first, detection of the p.Ala204Thr mutation; second, detecting large deletions or duplications by Multiplex Ligation-dependent Probe Amplification and Quantitative Multiplex PCR of Short Fluorescent Fragments; and third, sequencing of the coding and flanking regions of the whole CLCNKB gene. In our genetic diagnosis, 20 families presented with the p.Ala204Thr mutation. Of those, 15 patients (15 families) were homozygous (57.7% of overall patients). Another 8 patients (5 families) were compound heterozygous for the founder mutation together with a second one. Thus, 3 patients (2 siblings) presented with the c. -19-?_2053+? del deletion (comprising the entire gene); one patient carried the p.Val170Met mutation (exon 6); and 4 patients (3 siblings) presented with the novel p.Glu442Gly mutation (exon 14). On the other hand, another two patients carried two novel mutations in compound heterozygosis: one presented the p.Ile398_Thr401del mutation (exon 12) associated with the c. -19-?_2053+? del deletion, and the other one carried the c.1756+1G>A splice-site mutation (exon 16) as well as the already described p.Ala210Val change (exon 7). One case turned out to be negative in our genetic screening. In addition, 51 relatives were found to be heterozygous carriers of the described CLCNKB mutations. In conclusion, different mutations cause type III Bartter syndrome in Spain. The high prevalence of the p.Ala204Thr in Spanish families thus justifies an initial screen for this mutation. However, should it not be detected further investigation of the CLCNKB gene is warranted in clinically diagnosed families.
Collapse
Affiliation(s)
| | | | - Leire Madariaga
- Pediatric Nephrology, Cruces University Hospital, Bizkaia, Spain
- Department of Pediatrics, School of Medicine and Odontology, University of Basque Country UPV/EHU, Bizkaia, Spain
| | - Mireia Aguirre
- Pediatric Nephrology, Cruces University Hospital, Bizkaia, Spain
| | - Alvaro Madrid
- Pediatric Nephrology, Materno Infantil Vall d’Hebron Hospital, Barcelona, Spain
| | - Inmaculada Nadal
- Pediatric Nephrology, Virgen del Camino Hospital, Pamplona, Spain
| | | | - Elena Lucas
- Pediatrics, Manises Hospital, Valencia, Spain
| | - Julia Fijo
- Pediatric Nephrology, Virgen del Rocío Hospital, Sevilla, Spain
| | - Mar Espino
- Pediatric Nephrology, Fundación Alcorcón University Hospital, Madrid, Spain
| | | | - Luis Castaño
- Research Unit, Ciberer, Cruces University Hospital, Bizkaia, Spain
- Department of Pediatrics, School of Medicine and Odontology, University of Basque Country UPV/EHU, Bizkaia, Spain
| | - Gema Ariceta
- Pediatric Nephrology, Materno Infantil Vall d’Hebron Hospital, Barcelona, Spain
| | - RenalTube Group
- Research Unit, Ciberer, Cruces University Hospital, Bizkaia, Spain
- Pediatric Nephrology, Asturias Central University Hospital, Oviedo, Asturias, Spain
- Pediatric Nephrology, Nuestra Señora de Candelaria University Hospital, Tenerife, Canarias, Spain
| |
Collapse
|
7
|
|
8
|
ClC-5 regulates dentin development through TGF-beta1 pathway. Arch Oral Biol 2009; 54:1118-24. [PMID: 19878925 DOI: 10.1016/j.archoralbio.2009.09.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2009] [Revised: 09/14/2009] [Accepted: 09/26/2009] [Indexed: 11/21/2022]
Abstract
ClC-5 is one of the voltage-dependent chloride channel (ClC) family members. Mutations involving CLCN5 cause an X-linked nephropathy associated with Dent's disease. Some Clcn5 gene knockout (ClC-5 KO) mice have abnormal growth of the teeth; however, the expression and function of ClC-5 during tooth development is still unknown. Herein we report abnormal dentin structure, decreased DSPP and increased TGF-beta1 protein level in ClC-5 KO teeth. In odontoblast-like MDPC-23 cells, the mRNA levels of Tgfb1, Dspp and Dmp-1 were upregulated with Clcn5 RNAi after 48h treatment; whilst there was no change in those of TGF-beta receptor Tgfbr1 and Tgfbr2. We suggest that the dentin changes in ClC-5 KO mice might be a result of increasing TGF-beta1, and the interplay between ClC-5 and TGF-beta1 needs further identified.
Collapse
|
9
|
Bergler T, Stoelcker B, Jeblick R, Reinhold SW, Wolf K, Riegger GA, Krämer BK. High osmolality induces the kidney-specific chloride channel CLC-K1 by a serum and glucocorticoid-inducible kinase 1 MAPK pathway. Kidney Int 2008; 74:1170-7. [DOI: 10.1038/ki.2008.312] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
10
|
Krämer BK, Bergler T, Stoelcker B, Waldegger S. Mechanisms of Disease: the kidney-specific chloride channels ClCKA and ClCKB, the Barttin subunit, and their clinical relevance. ACTA ACUST UNITED AC 2008; 4:38-46. [DOI: 10.1038/ncpneph0689] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2007] [Accepted: 08/17/2007] [Indexed: 01/13/2023]
|
11
|
Tajima M, Hayama A, Rai T, Sasaki S, Uchida S. Barttin binds to the outer lateral surface of the ClC-K2 chloride channel. Biochem Biophys Res Commun 2007; 362:858-64. [PMID: 17767918 DOI: 10.1016/j.bbrc.2007.08.097] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2007] [Accepted: 08/13/2007] [Indexed: 10/22/2022]
Abstract
ClC-K chloride channels belong to the CLC chloride channel family and play an important role in transepithelial chloride transport in the kidney. To be functional, ClC-K channels need to be translocated to the plasma membranes after synthesis; the translocation requires the binding to its beta-subunit, barttin. The binding interaction between barttin and ClC-K channels has not been characterized, although the crystal structure of CLC was resolved. In the present study, we sought to clarify the binding sites of barttin in ClC-K2 by co-immunoprecipitation and immunofluorescence microscopy using various ClC-K2 mutants. The deletion of the carboxy-terminal portion of ClC-K2 up to leucine 91, a construct which contains the B domain alone, showed the binding ability to barttin. Since the CLC channel forms an internal antiparallel structure, domain J corresponds to domain B in the carboxy-terminal half of ClC-K. Accordingly, we made the carboxy-terminal half of ClC-K2 containing domain J and thereafter and its deletion mutants, and performed a similar co-immunoprecipitation study. As a result, only domain J was enough for binding to barttin. Immunofluorescence microscopy confirmed that the domains B and J as well as the full length ClC-K2 could be localized to the plasma membranes only when co-expressed with barttin. These results showed that barttin was able to bind to the domains that constitute the outer lateral surfaces of ClC-K2. This information regarding the binding sites will be useful for designing a new class of diuretics or anti-hypertensive agents that inhibit the interaction of ClC-K and barttin.
Collapse
Affiliation(s)
- Masato Tajima
- Department of Nephrology, Graduate School of Medicine, Tokyo Medical and Dental University, Tokyo, Japan
| | | | | | | | | |
Collapse
|
12
|
Chen YT, Tu JJ, Kao J, Zhou XK, Mazumdar M. Messenger RNA Expression Ratios among Four Genes Predict Subtypes of Renal Cell Carcinoma and Distinguish Oncocytoma from Carcinoma. Clin Cancer Res 2005; 11:6558-66. [PMID: 16166433 DOI: 10.1158/1078-0432.ccr-05-0647] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE Morphologic distinction among clear cell, papillary, and chromophobe types of renal cell carcinoma (RCC) can be difficult, as is the differential diagnosis between oncocytoma and RCC. Whether these renal tumors can be distinguished by their mRNA expression profile of a few selected genes was examined. EXPERIMENTAL DESIGN The expression of four genes in renal tumor was evaluated by quantitative reverse transcription-PCR: carbonic anhydrase IX (CA9), methylacyl-CoA racemase (AMACR), parvalbumin (PVALB), and chloride channel kb (CLCNKB). Thirty-one fresh-frozen and 63 formalin-fixed, paraffin-embedded tumor specimens were analyzed. RESULTS CA9 expression was highest in clear cell carcinoma and lowest in chromophobe RCC and in oncocytoma. AMACR expression was highest in papillary RCC, and CLCNKB was highest in chromophobe RCC/oncocytoma. PVALB was highest in chromophobe RCC, variable in oncocytoma, and low in clear cell and papillary types. Similar findings were observed in fresh-frozen and formalin-fixed specimens. The mRNA expression ratios among these genes (i.e., CA9/AMACR and AMACR/CLCNKB ratios) further accentuate the gene expression differences among these tumors, and a molecular diagnostic algorithm was established. This algorithm accurately classified the 31 fresh-frozen tumors into 14 clear cell, 5 papillary, 6 chromophobe, and 6 oncocytomas. In the formalin-fixed group, the molecular criteria accurately classified the cases into 15 clear cell, 16 papillary, and 32 in the chromophobe/oncocytoma group but could only separate some, but not all, oncocytomas from chromophobe RCC. CONCLUSIONS RNA expression ratios based on the four-gene panel can accurately classify subtypes of RCC as well as help distinguish some oncocytomas from chromophobe RCC.
Collapse
MESH Headings
- Adenocarcinoma, Clear Cell/genetics
- Adenocarcinoma, Clear Cell/pathology
- Adenoma, Oxyphilic/genetics
- Adenoma, Oxyphilic/pathology
- Algorithms
- Anion Transport Proteins/genetics
- Antigens, Neoplasm/genetics
- Carbonic Anhydrase IX
- Carbonic Anhydrases/genetics
- Carcinoma, Renal Cell/genetics
- Carcinoma, Renal Cell/pathology
- Chloride Channels/genetics
- Diagnosis, Differential
- Gene Expression Regulation, Neoplastic
- Humans
- Kidney Neoplasms/genetics
- Kidney Neoplasms/pathology
- Membrane Proteins/genetics
- Neoplasm Proteins/genetics
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Racemases and Epimerases/genetics
- Reverse Transcriptase Polymerase Chain Reaction/methods
- beta-Defensins/genetics
Collapse
Affiliation(s)
- Yao-Tseng Chen
- Department of Pathology and Laboratory Medicine, Weill Medical College, Cornell University, New York, NY 10021, USA.
| | | | | | | | | |
Collapse
|
13
|
Abstract
Numerous Cl- channels have been identified in the kidney using physiological approaches and thus are thought to be involved in a range of physiological processes, including vectorial transepithelial Cl- transport, cell volume regulation, and vesicular acidification. In addition, expression of genes from several Cl- channel gene families has also been observed. However, the molecular characteristics of a number of Cl- channels within the kidney are still unknown, and the physiological roles of Cl- channels identified by molecular means remain to be determined. A gene knockout approach using mice might shed further light on the characteristics of these various Cl- channels. In addition, study of diseases involving Cl- channels (channelopathies) might clarify the physiological role of specific Cl- channels. To date, more is known about CLC Cl- channels than any other Cl- channels within the kidney. This review focuses on the physiological roles of CLC Cl- channels within the kidney, particularly kidney-specific ClC-K Cl- channels, as well as the recently identified maxi anion channel in macula densa, which is involved in tubulo-glomerular feedback.
Collapse
Affiliation(s)
- Shinichi Uchida
- Department of Nephrology, Graduate School of Medicine, Tokyo Medical and Dental University, Tokyo 113-8519, Japan.
| | | |
Collapse
|
14
|
Carrithers SL, Ott CE, Hill MJ, Johnson BR, Cai W, Chang JJ, Shah RG, Sun C, Mann EA, Fonteles MC, Forte LR, Jackson BA, Giannella RA, Greenberg RN. Guanylin and uroguanylin induce natriuresis in mice lacking guanylyl cyclase-C receptor. Kidney Int 2004; 65:40-53. [PMID: 14675035 DOI: 10.1111/j.1523-1755.2004.00375.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND Guanylin (GN) and uroguanylin (UGN) are intestinally derived peptide hormones that are similar in structure and activity to the diarrhea-causing Escherichia coli heat-stable enterotoxins (STa). These secretagogues have been shown to affect fluid, Na+, K+, and Cl- transport in both the intestine and kidney, presumably by intracellular cyclic guanosine monophosphate (cGMP)-dependent signal transduction. However, the in vivo consequences of GN, UGN, and STa on renal function and their mechanism of action have yet to be rigorously tested. METHODS We hypothesized that intravenous administration of GN, UGN, or STa would cause an increase in natriuresis in wild-type mice via cGMP and guanylyl cyclase-C (GC-C, Gucy2c), the only known receptor for these peptide-hormones, and that the peptide-induced natriuresis would be blunted in genetically altered mice devoid of GC-C receptors (GC-C(-/-) null). RESULTS In wild-type mice using a modified renal clearance model, GN, UGN, and STa elicited significant natriuresis, kaliuresis, and diuresis as well as increased urinary cGMP levels in a time- and dose-dependent fashion. Absolute and fractional urinary sodium excretion levels were greatest approximately 40 minutes following a bolus infusion with pharmacologic doses of these peptides. Unexpectedly, GC-C(-/-) null mice also responded to the GN peptides similarly to that observed in wild-type mice. Glomerular filtration rate (GFR), blood pressure, and plasma cGMP in the mice (wild-type or GC-C(-/-) null) did not significantly vary between the vehicle- and peptide-treatment groups. The effects of UGN may also influence long-term renal function due to down-regulation of the Na+/K+ ATPase gamma-subunit and the Cl- channel ClC-K2 by 60% and 75%, respectively, as assessed by differential display polymerase chain reaction (PCR) (DD-PCR) and Northern blot analysis of kidney mRNA from mice treated with UGN. CONCLUSION GN, UGN, and STa act on the mouse kidney, in part, through a cGMP-dependent, GC-C-independent mechanism, causing significant natriuresis by renal tubular processes. UGN may have further long-term effects on the kidney by altering the expression of such transport-associated proteins as Na+/K+ ATPase and ClC-K2.
Collapse
MESH Headings
- Animals
- Animals, Suckling
- Bacterial Toxins/metabolism
- Bacterial Toxins/pharmacology
- Blotting, Northern
- Enterotoxins/metabolism
- Enterotoxins/pharmacology
- Escherichia coli Proteins
- Gastrointestinal Hormones/metabolism
- Gastrointestinal Hormones/pharmacology
- Guanylate Cyclase/genetics
- Guanylate Cyclase/metabolism
- Injections, Intravenous
- Mice
- Mice, Inbred Strains
- Mice, Mutant Strains
- Natriuresis/drug effects
- Natriuresis/physiology
- Natriuretic Peptides
- Peptides/metabolism
- Peptides/pharmacology
- RNA, Messenger/analysis
- Receptors, Enterotoxin
- Receptors, Guanylate Cyclase-Coupled
- Receptors, Peptide/genetics
- Receptors, Peptide/metabolism
Collapse
Affiliation(s)
- Stephen L Carrithers
- Department of Internal Medicine, Division of Infectious Diseases, Lexington VA Medical Center and University of Kentucky, Lexington, Kentucky 40506, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
15
|
Miyazaki H, Kaneko T, Uchida S, Sasaki S, Takei Y. Kidney-specific chloride channel, OmClC-K, predominantly expressed in the diluting segment of freshwater-adapted tilapia kidney. Proc Natl Acad Sci U S A 2002; 99:15782-7. [PMID: 12427972 PMCID: PMC137793 DOI: 10.1073/pnas.242611099] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The kidney plays an important role in osmoregulation in freshwater teleosts, which are exposed to the danger of osmotic loss of Na(+) and Cl(-). However, ion-transport mechanisms in the kidney are poorly understood, and ion transporters of the fish nephron have not been identified thus far. From Mozambique tilapia, Oreochromis mossambicus, we have cloned a chloride channel, which is a homologue of the mammalian kidney-specific chloride channel, ClC-K. The cDNA of the channel, named OmClC-K, encodes a protein whose amino acid sequence has high homology to Xenopus and mammalian ClC-K (Xenopus ClC-K, 41.8%; rat ClC-K2, 40.9%; rat ClC-K1, 40.1%). The mRNA of OmClC-K was expressed exclusively in the kidney, and the expression level of mRNA was increased more in freshwater-adapted fish than seawater-adapted fish. The immunohistochemical study using a specific antibody showed that OmClC-K-positive cells were specifically located in the distal nephron segments. Immunoelectron microscopy further showed that immunoreaction of OmClC-K was recognizable on the structure of basolateral membrane infoldings in the distal tubule cells. The localization of OmClC-K and its induction in hypoosmotic media suggest that OmClC-K is involved in Cl(-) reabsorption in the distal tubule of freshwater-adapted tilapia.
Collapse
Affiliation(s)
- Hiroaki Miyazaki
- Ocean Research Institute, University of Tokyo, 1-15-1 Minamidai, Nakano-ku, Japan.
| | | | | | | | | |
Collapse
|
16
|
Kobayashi K, Uchida S, Okamura HO, Marumo F, Sasaki S. Human CLC-KB gene promoter drives the EGFP expression in the specific distal nephron segments and inner ear. J Am Soc Nephrol 2002; 13:1992-8. [PMID: 12138129 DOI: 10.1097/01.asn.0000023434.47132.3d] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Human CLC-KB has been identified as a kidney-specific member of the CLC chloride channel family, and mutations of the human CLC-KB gene are known to cause Bartter syndrome type III. A precise understanding of the localization of this channel in the human kidney is imperative to our understanding of the pathophysiology, but this has remained unclear due to the high homology between human CLC-KB and CLC-KA, another kidney-specific member of the same family. The high intraspecies homology also rules out an exact correlation of the human isoforms (CLC-KA and CLC-KB) to the mouse and rat isoforms (CLC-K1 and CLC-K2, respectively). This study created transgenic mice harboring the enhanced green fluorescence protein (EGFP) gene driven by an 11-kbp human CLC-KB gene promoter. Three transgenic lines were generated, and all of them showed EGFP fluorescence in the kidney, with an identical pattern of localization to the thick ascending limb of Henle's loop, distal tubules, connecting tubules, and intercalated cells of the collecting duct. This localization is exactly the same as that of mouse CLC-K2 identified in a previous report (Kobayashi et al. J Am Soc Neph 12: 1327-1334, 2001). EGFP fluorescence was also detected in the inner ear, more specifically in marginal cells of the stria vascularis and dark cells of the vestibular labyrinth, suggesting that human CLC-KB could play an important role in the fluid transport mechanism of the inner ear. The results (1) confirmed that CLC-KB is the true human homologue of rat and mouse CLC-K2 and (2) established that the 11-kbp human CLC-KB gene promoter is sufficient to elicit the precise expression in specific cell types of the kidney and inner ear.
Collapse
Affiliation(s)
- Katsuki Kobayashi
- Departments of Pediatrics, Homeostasis Medicine and Nephrology, and Audio-Vestibular Neuroscience, Tokyo Medical and Dental University, Tokyo, Japan
| | | | | | | | | |
Collapse
|
17
|
Peters M, Jeck N, Reinalter S, Leonhardt A, Tönshoff B, Klaus G GÜ, Konrad M, Seyberth HW. Clinical presentation of genetically defined patients with hypokalemic salt-losing tubulopathies. Am J Med 2002; 112:183-90. [PMID: 11893344 DOI: 10.1016/s0002-9343(01)01086-5] [Citation(s) in RCA: 204] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
PURPOSE Hypokalemic salt-losing tubulopathies (Bartter-like syndromes) comprise a set of clinically and genetically distinct inherited renal disorders. Mutations in four renal membrane proteins involved in electrolyte reabsorption have been identified in these disorders: the furosemide-sensitive sodium-potassium-chloride cotransporter NKCC2, the potassium channel ROMK, the chloride channel ClC-Kb, and the thiazide-sensitive sodium-chloride cotransporter NCCT. The aim of this study was to characterize the clinical features associated with each mutation in a large cohort of genetically defined patients. PATIENTS AND METHODS The phenotypic characteristics of 65 patients with molecular defects in NKCC2, ROMK, ClC-Kb, or NCCT were collected retrospectively. RESULTS ROMK and NKCC2 patients presented with polyhydramnios, nephrocalcinosis, and hypo- or isosthenuria. Hypokalemia was less severe in the ROMK patients compared with the NKCC2 patients. In contrast, NCCT patients had hypocalciuria, hypomagnesemia, and marked hypokalemia. While this dissociation of renal calcium and magnesium handling was also observed in some ClC-Kb patients, a few ClC-Kb patients presented with hypercalciuria and hypo- or isosthenuria. CONCLUSIONS ROMK, NKCC2, and NCCT mutations usually have uniform clinical presentations, whereas mutations in ClC-Kb occasionally lead to phenotypic overlaps with the NCCT or, less commonly, with the ROMK/NKCC2 cohort. Based on these results, we propose an algorithm for the molecular diagnosis of hypokalemic salt-losing tubulopathies.
Collapse
Affiliation(s)
- Melanie Peters
- Department of Pediatrics, Philipps University Marburg, Marburg, Germany
| | | | | | | | | | | | | | | |
Collapse
|
18
|
Kobayashi K, Uchida S, Mizutani S, Sasaki S, Marumo F. Intrarenal and cellular localization of CLC-K2 protein in the mouse kidney. J Am Soc Nephrol 2001; 12:1327-1334. [PMID: 11423561 DOI: 10.1681/asn.v1271327] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
CLC-K2, a kidney-specific member of the CLC chloride channel family, is thought to play an important role in the transepithelial Cl(-) transport in the kidney. This consensus was first reached shortly after it was demonstrated that the mutations of the human CLCNKB gene resulted in Bartter's syndrome type III. To clarify the pathogenesis, the exact intrarenal and cellular localization of CLC-K2 by immunohistochemistry of the Clcnk1-/- mouse kidney were investigated by use of an anti-CLC-K antibody that recognized both CLC-K1 and CLC-K2. CLC-K2 is expressed in the thick ascending limb of Henle's loop and distal tubules, where it is localized to the basolateral membranes. The localization of CLC-K2 to these nephron segments strongly implies that CLC-K2 confers the basolateral chloride conductance in the thick ascending limb of Henle's loop and distal tubules, where Cl(-) is taken up by the bumetanide-sensitive Na-K-2Cl cotransporter or the thiazide-sensitive Na-Cl cotransporter at the apical membranes. CLC-K2 expression was also shown to extend into the connecting tubule in the basolateral membrane. CLC-K2 was found in basolateral membranes of the type A intercalated cells residing along the collecting duct. This localization strongly suggests that CLC-K2 confers the basolateral conductance in the type A intercalated cells where Cl(-) is taken up by the anion exchanger in exchange for HCO(3)(-) at the basolateral membranes. These aspects of CLC-K2 localization suggest that CLC-K2 is important in Cl(-) transport in the distal nephron segments.
Collapse
Affiliation(s)
- Katsuki Kobayashi
- Department of Pediatrics, Tokyo Medical and Dental University, School of Medicine, Tokyo, Japan
| | - Shinichi Uchida
- Second Department of Internal Medicine, Tokyo Medical and Dental University, School of Medicine, Tokyo, Japan
| | - Shuki Mizutani
- Department of Pediatrics, Tokyo Medical and Dental University, School of Medicine, Tokyo, Japan
| | - Sei Sasaki
- Second Department of Internal Medicine, Tokyo Medical and Dental University, School of Medicine, Tokyo, Japan
| | - Fumiaki Marumo
- Second Department of Internal Medicine, Tokyo Medical and Dental University, School of Medicine, Tokyo, Japan
| |
Collapse
|
19
|
Abstract
Cl- transport in the loop of Henle is responsible for reclamation of 25-40% of the filtered NaCl load and for the formation of dilute urine. Our understanding of the physiologic and molecular mechanisms responsible for Cl- reabsorption in both the thin ascending limb and thick ascending limb of Henle's loop has increased greatly over the last decade. Plasma membrane Cl- channels are known to play an integral role in transcellular Cl- transport in both the thin and thick ascending limbs. This review focuses on the functional characteristics and molecular identities of these Cl- channels, as well as the role of these channels in the pathophysiology of disease.
Collapse
Affiliation(s)
- W B Reeves
- Division of Nephrology, University of Arkansas College of Medicine and the John L McClellan Veterans Hospital, Little Rock, Arkansas 72205, USA.
| | | | | |
Collapse
|
20
|
Akizuki N, Uchida S, Sasaki S, Marumo F. Impaired solute accumulation in inner medulla of Clcnk1-/- mice kidney. Am J Physiol Renal Physiol 2001; 280:F79-87. [PMID: 11133517 DOI: 10.1152/ajprenal.2001.280.1.f79] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The CLC-K1 chloride channel is a kidney-specific CLC chloride channel expressed in the thin ascending limb of Henle's loop (tAL). Recently, we determined that Clcnk1-/- mice show nephrogenic diabetes insipidus (NDI). To investigate the pathogenesis of impaired urinary concentrating ability, we analyzed renal functions of Clcnk1-/- mice in more detail. The osmolar clearance-to-creatinine clearance ratio was not significantly different between Clcnk1+/- and Clcnk1+/+ mice. Fractional excretion of sodium, chloride, and urea was also not significantly affected in Clcnk1-/- mice. These results indicate that the polyuria observed in Clcnk1-/- mice was water diuresis and not osmotic diuresis. The papillary osmolarity in Clcnk1-/- mice was significantly lower than that in Clcnk1+/+ mice under a hydrated condition, and it did not increase even after water deprivation. Sodium and chloride contents in the inner medulla in Clcnk1-/- mice were at about one-half the levels observed in Clcnk1+/+ mice. Furthermore, the accumulation of urea was also impaired in Clcnk1-/- mice, suggesting that the overall countercurrent system was impaired by a defect of its single component, chloride transport in the tAL. The aldose reductase mRNA abundance in Clcnk1-/- mice was decreased, further evincing that inner medullary tonicity is decreased in Clcnk1-/- mice. We concluded that NDI in Clcnk1-/- mice resulted from an impairment in the generation of inner medullary hypertonicity by a dysfunction of the countercurrent systems.
Collapse
Affiliation(s)
- N Akizuki
- Second Department of Internal Medicine, Tokyo Medical and Dental University, Tokyo 113-8519, Japan
| | | | | | | |
Collapse
|
21
|
Sauvé R, Cai S, Garneau L, Klein H, Parent L. pH and external Ca(2+) regulation of a small conductance Cl(-) channel in kidney distal tubule. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1509:73-85. [PMID: 11118519 DOI: 10.1016/s0005-2736(00)00287-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
A single channel characterization of the Cl(-) channels in distal nephron was undertaken using vesicles prepared from plasma membranes of isolated rabbit distal tubules. The presence in this vesicle preparation of ClC-K type Cl(-) channels was first established by immunodetection using an antibody raised against ClC-K isoforms. A ClC-K1 based functional characterization was next performed by investigating the pH and external Ca(2+) regulation of a small conductance Cl(-) channel which we identified previously by channel incorporation experiments. Acidification of the cis (external) solution from pH 7.4 to 6.5 led to a dose-dependent inhibition of the channel open probability P(O). Similarly, changing the trans pH from 7.4 to 6.8 resulted in a 4-fold decrease of the channel P(O) with no effect on the channel conductance. Channel activity also appeared to be regulated by cis (external) Ca(2+) concentration, with a dose-dependent increase in channel activity as a function of the cis Ca(2+) concentration. It is concluded on the basis of these results that the small conductance Cl(-) channel present in rabbit distal tubules is functionally equivalent to the ClC-K1 channel in the rat. In addition, the present work constitutes the first single channel evidence for a chloride channel regulated by external Ca(2+).
Collapse
Affiliation(s)
- R Sauvé
- Département de Physiologie, Groupe de Recherche en Transport Membranaire, Université de Montréal, C.P. 6128, Succ. Centre-ville, Que., H3C 3J7, Montréal, Canada.
| | | | | | | | | |
Collapse
|
22
|
Itoh R, Kawamoto S, Miyamoto Y, Kinoshita S, Okubo K. Isolation and characterization of a Ca(2+)-activated chloride channel from human corneal epithelium. Curr Eye Res 2000; 21:918-25. [PMID: 11262615 DOI: 10.1076/ceyr.21.6.918.6983] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
PURPOSE Transparency of the cornea is maintained through the activity of secretory mechanisms in the epithelium and endothelium, which offset the tendency of the stroma to imbibe fluid and swell. These secretory mechanisms establish osmotic gradients thereby providing the osmotic driving forces for coupled fluid transport from the stroma into both the tears and the anterior chamber. To further characterize the mechanism of epithelial Cl secretion, we cloned a cDNA encoding a Ca(2+)-dependent chloride channel, an abundant mRNA in human corneal epithelium. We investigated the abundance of all known human chloride channels in corneal epithelium to identify those responsible for regulating chloride conductance in this tissue. METHODS For the isolation of a full-length cDNA clone, a probe was selected from a set of expressed sequenced tag (EST) clones classified as unique to corneal epithelium (http://bodymap. ims.u-tokyo.ac.jp). The expression patterns of the corresponding gene encoding novel chloride channel gene in human cornea and other tissues were examined by reverse transcription-polymerase chain reaction (RT-PCR). Quantitative PCR was performed to clarify the expression level of the novel chloride channel gene in cornea relative to that in other human tissues. RESULTS We cloned a new Ca(2+)-activated chloride channel, CLCA2, from corneal epithelium. The full length cDNA clone encoded 943 amino acids with 62% identity to bovine Ca(2+)-activated chloride channel. The CLCA2 gene mapped to human chromosome 1p32. Quantitative expression analysis by RT-PCR showed that it is the most abundant chloride channel in corneal epithelium. CONCLUSION High and tissue specific expression of the CLCA2 gene in human corneal epithelium implies an important role in corneal transparency maintenance.
Collapse
Affiliation(s)
- R Itoh
- Institute for Molecular and Cellular Biology, Osaka University, Suita, Osaka, Japan
| | | | | | | | | |
Collapse
|
23
|
Abstract
Chloride channels in the kidney are involved in important physiological functions such as cell volume regulation, acidification of intracellular vesicles, and transepithelial chloride transport. Among eight mammalian CLC chloride channels expressed in the kidney, three (CLC-K1, CLC-K2, and CLC-5) were identified to be related to kidney diseases in humans or mice. CLC-K1 mediates a transepithelial chloride transport in the thin ascending limb of Henle's loop and is essential for urinary concentrating mechanisms. CLC-K2 is a basolateral chloride channel in distal nephron segments and is necessary for chloride reabsorption. CLC-5 is a chloride channel in intracellular vesicles of proximal tubules and is involved in endocytosis. This review will cover the recent advances in research on the CLC chloride channels of the kidney with a special focus on the issues most necessary to understand their physiological roles in vivo, i.e., their intrarenal and cellular localization and their phenotypes of humans and mice that have their loss-of-function mutations.
Collapse
Affiliation(s)
- S Uchida
- Second Department of Internal Medicine, Tokyo Medical and Dental University, School of Medicine, Tokyo 113-8519, Japan.
| |
Collapse
|
24
|
Abstract
By the introduction of technological advancement in methods of structural analysis, electronics, and recombinant DNA techniques, research in physiology has become molecular. Additionally, focus of interest has been moving away from classical physiology to become increasingly centered on mechanisms of disease. A wonderful example for this development, as evident by this review, is the field of ion channel research which would not be nearly as advanced had it not been for human diseases to clarify. It is for this reason that structure-function relationships and ion channel electrophysiology cannot be separated from the genetic and clinical description of ion channelopathies. Unique among reviews of this topic is that all known human hereditary diseases of voltage-gated ion channels are described covering various fields of medicine such as neurology (nocturnal frontal lobe epilepsy, benign neonatal convulsions, episodic ataxia, hemiplegic migraine, deafness, stationary night blindness), nephrology (X-linked recessive nephrolithiasis, Bartter), myology (hypokalemic and hyperkalemic periodic paralysis, myotonia congenita, paramyotonia, malignant hyperthermia), cardiology (LQT syndrome), and interesting parallels in mechanisms of disease emphasized. Likewise, all types of voltage-gated ion channels for cations (sodium, calcium, and potassium channels) and anions (chloride channels) are described together with all knowledge about pharmacology, structure, expression, isoforms, and encoding genes.
Collapse
Affiliation(s)
- F Lehmann-Horn
- Department of Applied Physiology, University of Ulm, Ulm, Germany.
| | | |
Collapse
|
25
|
Rai T, Uchida S, Sasaki S, Marumo F. Isolation and characterization of kidney-specific CLC-K2 chloride channel gene promoter. Biochem Biophys Res Commun 1999; 261:432-8. [PMID: 10425202 DOI: 10.1006/bbrc.1999.1038] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
CLC-K1 and CLC-K2 are highly homologous kidney-specific chloride channels, but they are expressed in the different nephron segments. To understand the molecular mechanisms of kidney-specific and nephron-segment-specific expression of CLC-K channel genes, the rat ClC-K2 gene promoter was cloned and compared with that of CLC-K1. In the 1.5-kb pair 5'-flanking region of the CLC-K2 gene, no TATA box was identified around the transcriptional start site, and the proximal region (-32 to -68) was characterized by a GA-rich motif that had a significant sequence similarity to that of the previously isolated CLC-K1 gene promoter. In contrast, the distal portion did not have significant sequence similarity to that of CLC-K1. Reporter gene assay and gel-retardation analysis revealed that the GA-rich motif and the binding of a specific protein(s) to this element were indispensable for the basal promoter activity of the CLC-K2 gene. These results suggest that the GA-rich element may have an important role in the promoter activities of the kidney-specific CLC-K1 and -K2 genes, but that the GA-element alone is not sufficient for the strict regulation of nephron-segment-specific expression of CLC-K1 and CLC-K2 genes.
Collapse
Affiliation(s)
- T Rai
- Second Department of Internal Medicine, Tokyo Medical and Dental University, School of Medicine, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8519, Japan
| | | | | | | |
Collapse
|
26
|
Yoshikawa M, Uchida S, Yamauchi A, Miyai A, Tanaka Y, Sasaki S, Marumo F. Localization of rat CLC-K2 chloride channel mRNA in the kidney. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 276:F552-8. [PMID: 10198414 DOI: 10.1152/ajprenal.1999.276.4.f552] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To gain insight into the physiological role of a kidney-specific chloride channel, CLC-K2, the exact intrarenal localization was determined by in situ hybridization. In contrast to the inner medullary localization of CLC-K1, the signal of CLC-K2 in our in situ hybridization study was highly evident in the superficial cortex, moderate in the outer medulla, and absent in the inner medulla. To identify the nephron segments where CLC-K2 mRNA was expressed, we performed in situ hybridization of CLC-K2 and immunohistochemistry of marker proteins (Na+/Ca2+ exchanger, Na+-Cl- cotransporter, aquaporin-2 water channel, and Tamm-Horsfall glycoprotein) in sequential sections of a rat kidney. Among the tubules of the superficial cortex, CLC-K2 mRNA was highly expressed in the distal convoluted tubules, connecting tubules, and cortical collecting ducts. The expression of CLC-K2 in the outer and inner medullary collecting ducts was almost absent. In contrast, a moderate signal of CLC-K2 mRNA was observed in the medullary thick ascending limb of Henle's loop, but the signal in the cortical thick ascending limb of Henle's loop was low. These results clearly demonstrated that CLC-K2 was not colocalized with CLC-K1 and that its localization along the nephron segments was relatively broad compared with that of CLC-K1.
Collapse
Affiliation(s)
- M Yoshikawa
- Second Department of Internal Medicine, Tokyo Medical and Dental University, Tokyo 113-8519, Japan
| | | | | | | | | | | | | |
Collapse
|
27
|
Matsumura Y, Uchida S, Kondo Y, Miyazaki H, Ko SB, Hayama A, Morimoto T, Liu W, Arisawa M, Sasaki S, Marumo F. Overt nephrogenic diabetes insipidus in mice lacking the CLC-K1 chloride channel. Nat Genet 1999; 21:95-8. [PMID: 9916798 DOI: 10.1038/5036] [Citation(s) in RCA: 185] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
CLC-K1 is a kidney-specific chloride channel that mediates transepithelial chloride transport in the thin ascending limb of Henle's loop (tAL) in the inner medulla. Transport of NaCl in the tAL is thought to be a component of urinary concentration in a passive model of the countercurrent multiplication system, but there has been no direct evidence that CLC-K1 is involved in urine concentration. To analyse the physiological function of CLC-K1 in vivo, we generated mice lacking CLC-K1 by targeted gene disruption. Clcnk1-/- mice were physically normal appearance, but produced approximately five times more urine than Clcnk1+/- and Clcnk1+/+ mice. After 24 hours of water deprivation, Clcnk1-/- mice were severely dehydrated and lethargic, with a decrease of approximately 27% in body weight. Intraperitoneal injection of the V2 agonist 1-deamino-8-D-arginine vasopressin (dDAVP) induced a threefold increase in urine osmolarity in Clcnk1+/- and Clcnk1+/+ mice, whereas only a minimal increase was seen in Clcnk1-/- mice, indicating nephrogenic diabetes insipidus. After in vitro perfusion of the tAL, the lumen-to-bath chloride gradient did not produce a diffusion potential in Clcnk1-/- mice in contrast to Clcnk1+/+ and Clcnk1+/- mice. These results establish that CLC-K1 has a role in urine concentration, and that the countercurrent system in the inner medulla is involved in the generation and maintenance of hypertonic medullary interstitium.
Collapse
Affiliation(s)
- Y Matsumura
- Second Department of Internal Medicine, Tokyo Medical and Dental University, School of Medicine, Japan
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
28
|
Affiliation(s)
- I Kurtz
- UCLA School of Medicine, Los Angeles, California, USA
| |
Collapse
|
29
|
Tulk BM, Edwards JC. NCC27, a homolog of intracellular Cl- channel p64, is expressed in brush border of renal proximal tubule. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 274:F1140-9. [PMID: 9841507 DOI: 10.1152/ajprenal.1998.274.6.f1140] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
NCC27, a 27-kDa homolog of the intracellular chloride channel p64, was recently described as a chloride channel in nuclear membrane. We probed human Northern blots for NCC27 and found an approximately 1.7-kb message in all tissues examined, including kidney, the transcript being most abundant in heart and skeletal muscle.NCC27-specific antisera was raised to a COOH-terminal peptide derived from the NCC27 coding region. Using this antisera, we find NCC27 is expressed in an intracellular vesicular compartment in HeLa cells, PancI cells, and macrophages. In human and mouse kidney, NCC27 is expressed at low levels in most cells of the kidney. NCC27 is highly expressed in glomeruli, in periarterial smooth muscle, and in the apical membrane of a subset of cortical tubule cells. Double staining with nephron segment-specific lectins indicates that the NCC27-expressing cells are proximal tubule cells.
Collapse
Affiliation(s)
- B M Tulk
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA
| | | |
Collapse
|
30
|
Uchida S, Rai T, Yatsushige H, Matsumura Y, Kawasaki M, Sasaki S, Marumo F. Isolation and characterization of kidney-specific ClC-K1 chloride channel gene promoter. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 274:F602-10. [PMID: 9530278 DOI: 10.1152/ajprenal.1998.274.3.f602] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The rat ClC-K1 chloride channel is a kidney-specific member of the ClC chloride channel family found exclusively in the thin ascending limb of Henle's loop in the kidney. To gain insight into the mechanism(s) of kidney-specific expression of ClC-K1, a genomic clone that contains the 5'-flanking region of the rat ClC-K1 gene was isolated. A single transcription start site was located 84 bp upstream of the start codon. The sequence of the proximal 5'-flanking region contained an activator protein (AP)-3 site, a glucocorticoid-responsive element, several AP-2 sites, and several E-boxes, but it lacked a TATA box. To functionally express the promoter, the approximately 2.5-kb pair 5'-flanking region was ligated to a luciferase reporter gene and transfected into inner medullary (IM) cells, a stable ClC-K1-expressing cell line derived from the inner medulla of simian virus 40 transgenic mouse, and ClC-K1-nonexpressing cell lines. Luciferase activity was 7-to 24-fold greater in IM cells than those in nonexpressing cell lines, suggesting that the approximately 2.5-kb fragment contained cis-acting regulatory elements for cell-specific expression of the ClC-K1 gene. Deletion analysis revealed that this cell-specific promoter activity in IM cells was still present in the construct containing 51 bp of the 5'-flanking region but was lost in the -29 construct, clearly demonstrating that the 22 bp from -51 to -30 have a major role in the cell-specific activity of the ClC-K1 promoter. These 22 bp consist of purine-rich sequence (GGGGAGGGG-GAGGGGAG), and gel-retardation analysis demonstrated the existence of a specific protein(s) binding to this element in IM cells. These results suggest that the novel purine-rich element may play a key role in the activity of the ClC-K1 gene promoter.
Collapse
Affiliation(s)
- S Uchida
- Second Department of Internal Medicine, Tokyo Medical and Dental University, School of Medicine, Japan
| | | | | | | | | | | | | |
Collapse
|
31
|
Brennan TM, Landau D, Shalev H, Lamb F, Schutte BC, Walder RY, Mark AL, Carmi R, Sheffield VC. Linkage of infantile Bartter syndrome with sensorineural deafness to chromosome 1p. Am J Hum Genet 1998; 62:355-61. [PMID: 9463315 PMCID: PMC1376884 DOI: 10.1086/301708] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Bartter syndrome (BS) is a family of disorders manifested by hypokalemic hypochloremic metabolic alkalosis with normotensive hyperreninemic hyperaldosteronism. We evaluated a unique, inbred Bedouin kindred in which sensorineural deafness (SND) cosegregates with an infantile variant of the BS phenotype. Using a DNA-pooling strategy, we screened the human genome and successfully demonstrated linkage of this unique syndrome to chromosome 1p31. The genes for two kidney-specific chloride channels and a sodium/hydrogen antiporter, located near this region, were excluded as candidate genes. Although the search for the disease-causing gene in this family continues, this linkage further demonstrates the genetic heterogeneity of BS. In addition, the cosegregation of these phenotypes allows us to postulate that a single genetic alteration may be responsible for the SND and the BS phenotype. The identification and characterization of this gene would lead to a better understanding of the normal physiology of the kidney and the inner ear.
Collapse
Affiliation(s)
- T M Brennan
- Department of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
32
|
Marshansky V, Bourgoin S, Londoño I, Bendayan M, Maranda B, Vinay P. Receptor-mediated endocytosis in kidney proximal tubules: recent advances and hypothesis. Electrophoresis 1997; 18:2661-76. [PMID: 9580051 DOI: 10.1002/elps.1150181423] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Preparation of kidney proximal tubules in suspension allows the study of receptor-mediated endocytosis, protein reabsorption, and traffic of endosomal vesicles. The study of tubular protein transport in vitro coupled with that of the function of endosomal preparation offers a unique opportunity to investigate a receptor-mediated endocytosis pathway under physiological and pathological conditions. We assume that receptor-mediated endocytosis of albumin in kidney proximal tubules in situ and in vitro can be regulated, on the one hand, by the components of the acidification machinery (V-type H+-ATPase, Cl(-)-channel and Na+/H+-exchanger), giving rise to formation and dissipation of a proton gradient in endosomal vesicles, and, on the other hand, by small GTPases of the ADP-ribosylation factor (Arf)-family. In this paper we thus analyze the recent advances of the studies of cellular and molecular mechanisms underlying the identification, localization, and function of the acidification machinery (V-type H+-ATPase, Cl(-)-channel) as well as Arf-family small GTPases and phospholipase D in the endocytotic pathway of kidney proximal tubules. Also, we explore the possible functional interaction between the acidification machinery and Arf-family small GTPases. Finally, we propose the hypothesis of the regulation of translocation of Arf-family small GTPases by an endosomal acidification process and its role during receptor-mediated endocytosis in kidney proximal tubules. The results of this study will not only enhance our understanding of the receptor-mediated endocytosis pathway in kidney proximal tubules under physiological conditions but will also have important implications with respect to the functional consequences under some pathological circumstances. Furthermore, it may suggest novel targets and approaches in the prevention and treatment of various diseases (cystic fibrosis, Dent's disease, diabetes and autosomal dominant polycystic kidney disease).
Collapse
Affiliation(s)
- V Marshansky
- Centre de Recherche L.-C. Simard, Centre Hospitalier de l'Université de Montréal, Université de Montréal, Québec, Canada.
| | | | | | | | | | | |
Collapse
|
33
|
Jin W, Hopfer U. Dipeptide-induced Cl- secretion in proximal tubule cells. THE AMERICAN JOURNAL OF PHYSIOLOGY 1997; 273:C1623-31. [PMID: 9374648 DOI: 10.1152/ajpcell.1997.273.5.c1623] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
During a survey of dipeptides that might be transported by the renal PEPT2 transporter in proximal tubule cells, we discovered that acidic dipeptides could stimulate transient secretory anion current and conductance increases in intact cell monolayers. The stimulatory effect of acidic dipeptides was observed in several proximal tubule cell lines that have been recently developed by immortalization of early proximal tubule primary cultures from the Wistar-Kyoto and spontaneously hypertensive rat strains and humans, suggesting that this phenomenon is a characteristic of proximal tubule cells. The electrical current induced in intact monolayers by Ala-Asp, a representative of these acidic dipeptides, must represent Cl- secretion rather than Na+ or H+ absorption, because 1) it was Na+ independent, 2) it showed a pH dependence different from that of the PEPT2 cotransporter, and 3) it correlated with an Ala-Asp-induced increase in Cl- conductance of the apical membrane in basolaterally amphotericin B-permeabilized monolayers. The secretory current could be inhibited by stilbene disulfonates, but not diphenylamine-2-carboxylates, suggesting a non-cystic fibrosis transmembrane conductance regulator type of Cl- conductance. The effect of Ala-Asp was dose dependent, with an apparent 50% effective concentration of approximately 1 mM. Ala-Asp also produced intracellular acidification, suggesting that acidic dipeptides are also substrates for an H(+)-peptide cotransporter.
Collapse
Affiliation(s)
- W Jin
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, USA
| | | |
Collapse
|