1
|
Kožich V, Schwahn BC, Sokolová J, Křížková M, Ditroi T, Krijt J, Khalil Y, Křížek T, Vaculíková-Fantlová T, Stibůrková B, Mills P, Clayton P, Barvíková K, Blessing H, Sykut-Cegielska J, Dionisi-Vici C, Gasperini S, García-Cazorla Á, Haack TB, Honzík T, Ješina P, Kuster A, Laugwitz L, Martinelli D, Porta F, Santer R, Schwarz G, Nagy P. Human ultrarare genetic disorders of sulfur metabolism demonstrate redundancies in H 2S homeostasis. Redox Biol 2022; 58:102517. [PMID: 36306676 PMCID: PMC9615310 DOI: 10.1016/j.redox.2022.102517] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 10/17/2022] [Accepted: 10/17/2022] [Indexed: 11/06/2022] Open
Abstract
Regulation of H2S homeostasis in humans is poorly understood. Therefore, we assessed the importance of individual enzymes in synthesis and catabolism of H2S by studying patients with respective genetic defects. We analyzed sulfur compounds (including bioavailable sulfide) in 37 untreated or insufficiently treated patients with seven ultrarare enzyme deficiencies and compared them to 63 controls. Surprisingly, we observed that patients with severe deficiency in cystathionine β-synthase (CBS) or cystathionine γ-lyase (CSE) - the enzymes primarily responsible for H2S synthesis - exhibited increased and normal levels of bioavailable sulfide, respectively. However, an approximately 21-fold increase of urinary homolanthionine in CBS deficiency strongly suggests that lacking CBS activity is compensated for by an increase in CSE-dependent H2S synthesis from accumulating homocysteine, which suggests a control of H2S homeostasis in vivo. In deficiency of sulfide:quinone oxidoreductase - the first enzyme in mitochondrial H2S oxidation - we found normal H2S concentrations in a symptomatic patient and his asymptomatic sibling, and elevated levels in an asymptomatic sibling, challenging the requirement for this enzyme in catabolizing H2S under physiological conditions. Patients with ethylmalonic encephalopathy and sulfite oxidase/molybdenum cofactor deficiencies exhibited massive accumulation of thiosulfate and sulfite with formation of large amounts of S-sulfocysteine and S-sulfohomocysteine, increased renal losses of sulfur compounds and concomitant strong reduction in plasma total cysteine. Our results demonstrate the value of a comprehensive assessment of sulfur compounds in severe disorders of homocysteine/cysteine metabolism and provide evidence for redundancy and compensatory mechanisms in the maintenance of H2S homeostasis. Cystathionine γ-lyase can compensate for decreased H2S synthesis in cystathionine β-synthase deficiency. Sulfide:quinone oxidoreductase deficiency is compatible with normal H2S plasma levels under non-stressed conditions. Persulfide dioxygenase deficiency (ethylmalonic encephalopathy) causes the largest accumulation of H2S among disorders of sulfur metabolism. Excess sulfite forms S-sulfocysteine and S-sulfohomocysteine, and interferes with vitamin B6 metabolism. S-sulfocysteine correlates directly with sulfite and is a stable biomarker of sulfite accumulation.
Collapse
Affiliation(s)
- Viktor Kožich
- Department of Pediatrics and Inherited Metabolic Disorders, Charles University-First Faculty of Medicine and General University Hospital in Prague, Prague, Czech Republic,Corresponding author. Department of Pediatrics and Inherited Metabolic Disorders, Charles University, Medicine and General University Hospital in Prague, Ke Karlovu 2, 128 08, Praha 2, Czech Republic.
| | - Bernd C Schwahn
- Manchester Centre for Genomic Medicine, St Mary's Hospital, Manchester University NHS Foundation Trust, Health Innovation Manchester, Manchester, United Kingdom
| | - Jitka Sokolová
- Department of Pediatrics and Inherited Metabolic Disorders, Charles University-First Faculty of Medicine and General University Hospital in Prague, Prague, Czech Republic
| | - Michaela Křížková
- Department of Pediatrics and Inherited Metabolic Disorders, Charles University-First Faculty of Medicine and General University Hospital in Prague, Prague, Czech Republic
| | - Tamas Ditroi
- Department of Molecular Immunology and Toxicology and the National Tumor Biology Laboratory, National Institute of Oncology, Budapest, Hungary
| | - Jakub Krijt
- Department of Pediatrics and Inherited Metabolic Disorders, Charles University-First Faculty of Medicine and General University Hospital in Prague, Prague, Czech Republic
| | - Youssef Khalil
- Genetics & Genomic Medicine Department, UCL GOS Institute of Child Health, London, UK
| | - Tomáš Křížek
- Department of Analytical Chemistry, Faculty of Science, Charles University, Prague, Czech Republic
| | - Tereza Vaculíková-Fantlová
- Department of Pediatrics and Inherited Metabolic Disorders, Charles University-First Faculty of Medicine and General University Hospital in Prague, Prague, Czech Republic
| | - Blanka Stibůrková
- Department of Pediatrics and Inherited Metabolic Disorders, Charles University-First Faculty of Medicine and General University Hospital in Prague, Prague, Czech Republic,Institute of Rheumatology, Prague, Czech Republic
| | - Philippa Mills
- Genetics & Genomic Medicine Department, UCL GOS Institute of Child Health, London, UK
| | - Peter Clayton
- Genetics & Genomic Medicine Department, UCL GOS Institute of Child Health, London, UK
| | - Kristýna Barvíková
- Department of Pediatrics and Inherited Metabolic Disorders, Charles University-First Faculty of Medicine and General University Hospital in Prague, Prague, Czech Republic
| | - Holger Blessing
- Kinder- und Jugendklinik, Universitätsklinikum Erlangen, Erlangen, Germany
| | - Jolanta Sykut-Cegielska
- Department of Inborn Errors of Metabolism and Pediatrics, The Institute of Mother and Child, Warsaw, Poland
| | - Carlo Dionisi-Vici
- Division of Metabolism, Bambino Gesù Children's Hospital IRCCS, Rome, Italy
| | - Serena Gasperini
- Metabolic Rare Diseases Unit, Department of Pediatrics, Fondazione MBBM, San Gerardo Hospital, Monza, Italy
| | - Ángeles García-Cazorla
- Inborn Errors of Metabolism Unit, Institut de Recerca Sant Joan de Déu and CIBERER-ISCIII, Barcelona, Spain
| | - Tobias B Haack
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
| | - Tomáš Honzík
- Department of Pediatrics and Inherited Metabolic Disorders, Charles University-First Faculty of Medicine and General University Hospital in Prague, Prague, Czech Republic
| | - Pavel Ješina
- Department of Pediatrics and Inherited Metabolic Disorders, Charles University-First Faculty of Medicine and General University Hospital in Prague, Prague, Czech Republic
| | - Alice Kuster
- Center for Inborn Errors of Metabolism, Pediatric Intensive Care Unit, University Hospital of Nantes, Nantes, France
| | - Lucia Laugwitz
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany,Department of Neuropediatrics, Developmental Neurology and Social Pediatrics, University of Tübingen, Tübingen, Germany
| | - Diego Martinelli
- Division of Metabolism, Bambino Gesù Children's Hospital IRCCS, Rome, Italy
| | - Francesco Porta
- Department of Pediatrics, Metabolic diseases, AOU Città della Salute e della Scienza, University of Torino, Torino, Italy
| | - René Santer
- Department of Pediatrics, University Medical Centre Eppendorf, Hamburg, Germany
| | - Guenter Schwarz
- Institute of Biochemistry, Department of Chemistry, University of Cologne, Cologne, Germany,Corresponding author. Institute of Biochemistry, Department of Chemistry, University of Cologne, Zuelpicher Str. 4750674, Koeln, Germany.
| | - Peter Nagy
- Department of Molecular Immunology and Toxicology and the National Tumor Biology Laboratory, National Institute of Oncology, Budapest, Hungary,Department of Anatomy and Histology, ELKH-ÁTE Laboratory of Redox Biology, University of Veterinary Medicine, Budapest, Hungary,Chemistry Institute, University of Debrecen, Debrecen, Hungary,Corresponding author. Department of Molecular Immunology and Toxicology, National Institute of Oncology, 1122 Budapest, Ráth György u. 7-9., Hungary.
| |
Collapse
|
2
|
Bröer S. Amino acid transport across mammalian intestinal and renal epithelia. Physiol Rev 2008; 88:249-86. [PMID: 18195088 DOI: 10.1152/physrev.00018.2006] [Citation(s) in RCA: 614] [Impact Index Per Article: 38.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The transport of amino acids in kidney and intestine is critical for the supply of amino acids to all tissues and the homeostasis of plasma amino acid levels. This is illustrated by a number of inherited disorders affecting amino acid transport in epithelial cells, such as cystinuria, lysinuric protein intolerance, Hartnup disorder, iminoglycinuria, dicarboxylic aminoaciduria, and some other less well-described disturbances of amino acid transport. The identification of most epithelial amino acid transporters over the past 15 years allows the definition of these disorders at the molecular level and provides a clear picture of the functional cooperation between transporters in the apical and basolateral membranes of mammalian epithelial cells. Transport of amino acids across the apical membrane not only makes use of sodium-dependent symporters, but also uses the proton-motive force and the gradient of other amino acids to efficiently absorb amino acids from the lumen. In the basolateral membrane, antiporters cooperate with facilitators to release amino acids without depleting cells of valuable nutrients. With very few exceptions, individual amino acids are transported by more than one transporter, providing backup capacity for absorption in the case of mutational inactivation of a transport system.
Collapse
Affiliation(s)
- Stefan Bröer
- School of Biochemistry and Molecular Biology, Australian National University, Canberra, Australian Capital Territory, Australia.
| |
Collapse
|
3
|
Pineda M, Font M, Bassi MT, Manzoni M, Borsani G, Marigo V, Fernández E, Río RMD, Purroy J, Zorzano A, Nunes V, Palacín M. The amino acid transporter asc-1 is not involved in cystinuria. Kidney Int 2004; 66:1453-64. [PMID: 15458438 DOI: 10.1111/j.1523-1755.2004.00908.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND The human amino acid transporter asc-1 (SLC7A10) exhibits substrate selectivity for small neutral amino acids, including cysteine, is expressed in kidney, is located close to the cystinuria B gene and presents sequence variants (e.g., E112D) in some cystinuria patients. We have cloned human asc-1, assessed its transport characteristics, localized its expression in kidney, searched for mutations in cystinuria patients, and tested the transport function of variant E112D. METHODS We used an EST-based homology cloning strategy. Transport characteristics of asc-1 were assessed by coexpression with 4F2hc in Xenopus oocytes and HeLa cells. Localization of asc-1 mRNA in kidney was assessed by in situ hybridization. Exons and intron-exon boundaries were polymerase chain reaction (PCR)-amplified from blood cell DNA and mutational screening was performed by single-stranded conformational polymorphism (SSCP). RESULTS Asc-1 reaches the plasma membrane in HeLa cells, unlike in oocytes, most probably by interaction with endogenous 4F2hc and presents similar transport characteristics to those in oocytes coexpressing asc-1/4F2hc. Asc-1 mediates a substantial efflux of alanine in a facilitated diffusion mode of transport. Expression of asc-1 mRNA localized to Henle's loop, distal tubules, and collecting ducts. Finally, SLC7A10 polymorphisms were identified in cystinuria probands and the SLC7A10 sequence variant E112D showed full transport activity. CONCLUSION The lack of expression of asc-1 in the proximal tubule indicates that it plays no role in the bulk of renal reabsorption of amino acids. No mutations causing cystinuria have been found in SLC7A10. The facilitated diffusion mode of transport and the expression in distal nephron suggest a role for asc-1 in osmotic adaptation.
Collapse
Affiliation(s)
- Marta Pineda
- Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Barcelona, Spain
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
4
|
Fernández E, Carrascal M, Rousaud F, Abián J, Zorzano A, Palacín M, Chillarón J. rBAT-b(0,+)AT heterodimer is the main apical reabsorption system for cystine in the kidney. Am J Physiol Renal Physiol 2002; 283:F540-8. [PMID: 12167606 DOI: 10.1152/ajprenal.00071.2002] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mutations in the rBAT and b(0,+)AT genes cause type I and non-type I cystinuria, respectively. The disulfide-linked rBAT-b(0,+)AT heterodimer mediates high-affinity transport of cystine and dibasic amino acids (b(0,+)-like activity) in heterologous cell systems. However, the significance of this heterodimer for cystine reabsorption is unknown, as direct evidence for such a complex in vivo is lacking and the expression patterns of rBAT and b(0,+)AT along the proximal tubule are opposite. We addressed this issue by biochemical means. Western blot analysis of mouse and human kidney brush-border membranes showed that rBAT and b(0,+)AT were solely expressed as heterodimers of identical size and that both proteins coprecipitated. Moreover, quantitative immunopurification of b(0,+)AT followed by SDS-PAGE and mass spectrometry analysis established that b(0,+)AT heterodimerizes exclusively with rBAT. Together with cystine reabsorption data, our results demonstrate that a decreasing expression gradient of heterodimeric rBAT-b(0,+)AT along the proximal tubule is responsible for virtually all apical cystine reabsorption. As a corollary of the above, there should be an excess of rBAT expression over that of b(0,+)AT protein in the kidney. Indeed, complete immunodepletion of b(0,+)AT did not coprecipitate >20-30% of rBAT. Therefore, another rBAT-associated subunit may be present in latter parts of the proximal tubule.
Collapse
Affiliation(s)
- Esperanza Fernández
- Departament de Bioquímica i Biologia Molecular, Facultat de Biologia, Universitat de Barcelona, Barcelona 08028, Spain
| | | | | | | | | | | | | |
Collapse
|
5
|
Wagner CA, Lang F, Bröer S. Function and structure of heterodimeric amino acid transporters. Am J Physiol Cell Physiol 2001; 281:C1077-93. [PMID: 11546643 DOI: 10.1152/ajpcell.2001.281.4.c1077] [Citation(s) in RCA: 258] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Heterodimeric amino acid transporters are comprised of two subunits, a polytopic membrane protein (light chain) and an associated type II membrane protein (heavy chain). The heavy chain rbAT (related to b(0,+) amino acid transporter) associates with the light chain b(0,+)AT (b(0,+) amino acid transporter) to form the amino acid transport system b(0,+), whereas the homologous heavy chain 4F2hc interacts with several light chains to form system L (with LAT1 and LAT2), system y(+)L (with y(+)LAT1 and y(+)LAT2), system x (with xAT), or system asc (with asc1). The association of light chains with the two heavy chains is not unambiguous. rbAT may interact with LAT2 and y(+)LAT1 and vice versa; 4F2hc may interact with b(0,+)AT when overexpressed. 4F2hc is necessary for trafficking of the light chain to the plasma membrane, whereas the light chains are thought to determine the transport characteristics of the respective heterodimer. In contrast to 4F2hc, mutations in rbAT suggest that rbAT itself takes part in the transport besides serving for the trafficking of the light chain to the cell surface. Heavy and light subunits are linked together by a disulfide bridge. The disulfide bridge, however, is not necessary for the trafficking of rbAT or 4F2 heterodimers to the membrane or for the functioning of the transporter. However, there is experimental evidence that the disulfide bridge in the 4F2hc/LAT1 heterodimer plays a role in the regulation of a cation channel. These results highlight complex interactions between the different subunits of heterodimeric amino acid transporters and suggest that despite high grades of homology, the interactions between rbAT and 4F2hc and their respective partners may be different.
Collapse
Affiliation(s)
- C A Wagner
- Department of Cellular and Molecular Physiology, School of Medicine, Yale University, New Haven, Connecticut 06520, USA.
| | | | | |
Collapse
|
6
|
Mora C, Chillarón J, Calonge MJ, Forgo J, Testar X, Nunes V, Murer H, Zorzano A, Palacín M. The rBAT gene is responsible for L-cystine uptake via the b0,(+)-like amino acid transport system in a "renal proximal tubular" cell line (OK cells). J Biol Chem 1996; 271:10569-76. [PMID: 8631857 DOI: 10.1074/jbc.271.18.10569] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Several studies have shown that the cRNA of human, rabbit, or rat rBAT induces in Xenopus oocytes sodium-independent, high affinity uptake of L-cystine via a system b0,(+)-like amino acid exchanger. We have shown that mutations in rBAT cause type I cystinuria (Calonge, M. J., Gasparini, P., Chillarón, J., Chillón, M., Gallucci, M., Rousaud, F., Zelante, L., Testar, X., Dallapiccola, B., Di Silverio, F., Barceló, P., Estivill, X., Zorzano, A., Nunes, V., and Palacín, M. (1994) Nat. Genet. 6, 420-425; Calonge, M. J., Volipini, V., Bisceglia, L., Rousaud, F., De Sanctis, L., Beccia, E., Zelante, L., Testar, X., Zorzano, A., Estivill, X., Gasparini, P., Nunes, V., and Palacín, M. (1995) Proc. Natl. Acad. Sci. U. S. A. 92, 9667-9671). Apart from oocytes, no other expression system has been used for transfection of functional rBAT activity. Furthermore, the b0,(+)-like transport activity has not been clearly described in the kidney or intestine. Here, we report that a "proximal tubular-like" cell line derived from opossum kidney (OK cells) expresses an rBAT transcript. Poly(A)+ RNA from OK cells induced by system b0,(+)-like transport activity in oocytes. This was hybrid-depleted by human rBAT antisense oligonucleotides. A polymerase chain reaction-amplified cDNA fragment (approximately 700 base pairs) from OK cell RNA corresponds to an rBAT protein fragment 65-69% identical to those from human, rabbit and rat kidneys. We have also examined transport of l-cystine in OK cells and found characteristics very similar to the amino acid exchanger activity induced by rBAT cRNA in oocytes. Uptake of L-cystine was of high affinity, sodium-independent and shared with L-arginine and L-leucine. It was trans-stimulated by amino acids with the same specificity as rBAT-induced transport activity in oocytes. Furthermore, it was localized to the apical pole of confluent OK cells. To demonstrate that the rBAT protein is functionally related to this transport activity, we have transfected OK cells with human rBAT antisense and sense sequences. Transfection with rBAT antisense, but not with rBAT sense, resulted in the specific reduction of rBAT mRNA expression and b0,(+)-like transport activity. These results demonstrate that rBAT is functionally related to the L-cystine uptake via system b0,(+)-like in the apical pole of the renal OK cell line.
Collapse
Affiliation(s)
- C Mora
- Department of Biochemistry and Molecular Biology, Faculty of Biology, Universitat de Barcelona, Spain
| | | | | | | | | | | | | | | | | |
Collapse
|
7
|
Riahi-Esfahani S, Jessen H, R�igaard H. Comparative study of the uptake of L-cysteine and L-cystine in the renal proximal tubule. Amino Acids 1995; 8:247-64. [DOI: 10.1007/bf00806822] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/1994] [Accepted: 12/12/1994] [Indexed: 11/29/2022]
|
8
|
Christenson HN. Is the broad range amino acid transporter which is induced by a renal microvillar cDNA clone the cystinuria gene? Nutr Rev 1994; 52:210-2. [PMID: 7898785 DOI: 10.1111/j.1753-4887.1994.tb01423.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
On expression cloning in Xenopus oocytes, the renal cDNA expressed functionally in both the rat and human proximal tubule yields an amino acid transporter with properties generally consistent with representation of the cystinuria gene.
Collapse
Affiliation(s)
- H N Christenson
- Department of Pediatrics, University of California, San Diego
| |
Collapse
|
9
|
Calonge MJ, Gasparini P, Chillarón J, Chillón M, Gallucci M, Rousaud F, Zelante L, Testar X, Dallapiccola B, Di Silverio F. Cystinuria caused by mutations in rBAT, a gene involved in the transport of cystine. Nat Genet 1994; 6:420-5. [PMID: 8054986 DOI: 10.1038/ng0494-420] [Citation(s) in RCA: 238] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Cystinuria is a classic heritable aminoaciduria that involves the defective transepithelial transport of cystine and dibasic amino acids in the kidney and intestine. Six missense mutations in the human rBAT gene, which is involved in high-affinity transport of cystine and dibasic amino acids in kidney and intestine, segregate with cystinuria. These mutations account for 30% of the cystinuria chromosomes studied. Homozygosity for the most common mutation (M467T) was detected in three cystinuric siblings. Mutation M467T nearly abolished the amino acid transport activity induced by rBAT in Xenopus oocytes. These results establish rBAT as a cystinuria gene.
Collapse
Affiliation(s)
- M J Calonge
- Departament de Genética Molecular (IRO), Hospital Duran i Reynals, Barcelona, Spain
| | | | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Furriols M, Chillarón J, Mora C, Castelló A, Bertran J, Camps M, Testar X, Vilaró S, Zorzano A, Palacín M. rBAT, related to L-cysteine transport, is localized to the microvilli of proximal straight tubules, and its expression is regulated in kidney by development. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(19)74218-5] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|
11
|
Pickel VM, Nirenberg MJ, Chan J, Mosckovitz R, Udenfriend S, Tate SS. Ultrastructural localization of a neutral and basic amino acid transporter in rat kidney and intestine. Proc Natl Acad Sci U S A 1993; 90:7779-83. [PMID: 8356084 PMCID: PMC47226 DOI: 10.1073/pnas.90.16.7779] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
A sodium-independent neutral and basic amino acid transporter (NBAT) from rat kidney was recently cloned and its amino acid sequence deduced. We used light and electron microscopic immunoperoxidase labeling to determine the cellular localization of NBAT in rat kidney and small intestine. The localization was carried out using site-directed antisera raised against synthetic peptides within NBAT. The most prominent localization of NBAT was in microvilli of epithelial cells lining renal proximal tubules. Microvilli of small intestinal epithelia were less frequently immunoreactive. Unexpectedly, the most intense labeling in the small intestine was seen within enteroendocrine cells and submucosal neurons. The neuronal labeling was highly localized within dense core vesicles in axon terminals apposed to the basal lamina near fenestrated blood vessels. These results support the proposal that NBAT plays a role in reabsorption of amino acids in renal tubules. In addition, they suggest that NBAT (or NBAT-like proteins) may have multiple functions in the small intestine, including luminal uptake of amino acids and vesicular uptake of related substrates into enteroendocrine cells and enteric neurons.
Collapse
Affiliation(s)
- V M Pickel
- Department of Neurology and Neuroscience, Cornell University Medical College, New York, NY 10021
| | | | | | | | | | | |
Collapse
|
12
|
Lee WS, Wells RG, Sabbag RV, Mohandas TK, Hediger MA. Cloning and chromosomal localization of a human kidney cDNA involved in cystine, dibasic, and neutral amino acid transport. J Clin Invest 1993; 91:1959-63. [PMID: 8486766 PMCID: PMC288191 DOI: 10.1172/jci116415] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
We have recently cloned, sequenced, and characterized a rat kidney cDNA (D2) that stimulates cystine as well as dibasic and neutral amino acid transport. In order to evaluate the role of this protein in human inherited diseases such as cystinuria, we have isolated a human D2 clone (D2H) by low stringency screening of a human kidney cDNA library using the radiolabeled D2 insert as a probe. The D2H cDNA is 2284 nucleotides long and encodes a 663 amino acid protein that is 80% identical to the rat D2 amino acid sequence and 86% to that of the rabbit homologue rBAT. Microinjection of in vitro transcribed D2H cRNA into Xenopus oocytes induced uptake of cystine as well as dibasic and neutral amino acids in a pattern similar to that of rat D2 and rabbit rBAT. Both neutral and dibasic amino acids inhibited the D2H-induced uptake of cystine. Northern blot analysis demonstrated that D2H, like D2 and rBAT, is expressed strongly in the kidney and intestine. Southern blot analysis of genomic DNA from a panel of mouse-human somatic cell hybrids showed that the human gene for D2H resides on chromosome 2.
Collapse
Affiliation(s)
- W S Lee
- Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts 02115
| | | | | | | | | |
Collapse
|
13
|
Scriver CR, Tenenhouse HS. Mendelian Phenotypes as “Probes” of Renal Transport Systems for Amino Acids and Phosphate. Compr Physiol 1992. [DOI: 10.1002/cphy.cp080242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
14
|
Silbernagl S. Tubular Transport of Amino Acids and Small Peptides. Compr Physiol 1992. [DOI: 10.1002/cphy.cp080241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
15
|
Abstract
Amino acids are reabsorbed from the tubular lumen by a saturable, carrier-mediated, concentrative transport mechanism driven by a Na+ electrochemical gradient across the luminal membrane. This process is followed by efflux mainly via carrier-mediated, Na+-independent facilitated diffusion across the basolateral membrane. Individual amino acids may have two or more Na+-dependent transport systems with different kinetic characteristics along the luminal membrane of the proximal tubule, thereby enabling very efficient amino acid reabsorption. Dual Na+-coupled transport pathways for some amino acids located in both the luminal and the peritubular membranes may operate in concert to provide the tubular epithelial cell with essential nutrients. One or more Na+ ions, H+, Cl- and in the case of acidic amino acids, K+ ion, may be involved in the translocation of the carrier complex. For most amino acids this process is electrogenic positive, favored by a negative cell interior. At least seven distinct, but largely interacting, Na+-dependent amino acid transport systems have been identified in the brush border membrane. A diet-induced adaptation in Na+-coupled taurine transport and acidosis-induced adaptive response in Na+-dependent glutamine transport are expressed at the luminal and the basolateral membrane surfaces, respectively. The aminoaciduria of early life may be related to a rapid dissipation of the Na+ electrochemical gradient necessary for amino acid reabsorption.
Collapse
Affiliation(s)
- I Zelikovic
- Department of Pediatrics, University of Tennessee, College of Medicine, Memphis
| | | |
Collapse
|
16
|
Abstract
109Cd was injected into the lumen of superficial proximal or distal tubules of rat kidneys, and recovery in the pelvic urine from the ipsilateral kidney was measured. Fractional recovery of labeled inulin always exceeded 90%. About 70% of injected inorganic Cd (CdCl2) was taken up by the epithelium of proximal tubules, while more than 90% of the injected amount was recovered after distal microinjection. The proximal fractional Cd uptake of a 1:1 (molar) Cd-L-cysteine complex was 82%, but was below 60% for a 5-10:1 molar ratio of cysteine:Cd. The chelate Cd-pentetic acid was recovered in final urine nearly quantitatively after proximal or distal microinjection. Fractional uptake of 109Cd from a Cd-metallothionein (Mt) complex, following proximal microinjection, ranged between 17 (Cd-Mt 0.19 mM) and 8% (Cd-Mt 1.5 mM). It is concluded that luminal Cd uptake by the tubular epithelium depends markedly on the chemical form of Cd and, when present, occurs mostly or exclusively in proximal tubules.
Collapse
Affiliation(s)
- E Felley-Bosco
- Institut de Pharmacologie de l'Université, Lausanne, Switzerland
| | | |
Collapse
|
17
|
Bannai S. Transport of cystine and cysteine in mammalian cells. BIOCHIMICA ET BIOPHYSICA ACTA 1984; 779:289-306. [PMID: 6383474 DOI: 10.1016/0304-4157(84)90014-5] [Citation(s) in RCA: 236] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
|
18
|
Schafer JA, Watkins ML. Transport of L-cystine in isolated perfused proximal straight tubules. Pflugers Arch 1984; 401:143-51. [PMID: 6433321 DOI: 10.1007/bf00583874] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Unidirectional fluxes of L-35S-cystine and intracellular 35S activity were measured in isolated perfused segments of rabbit proximal straight tubule. The absorptive (lumen-to-both) flux of L-35S-cysteine showed a tendency toward saturation within the concentration limits imposed by the low solubility of cystine (0.3 mmol . l-1). In contrast, for the bath-to-lumen fluxes, there was a linear relation between the bathing solution concentration of L-35S-cystine and the rate of 35S appearance in the lumen. Nonlinear fitting of both sets of unidirectional flux data gave a maximal cystine transport rate (Jmax) of 1.45 +/- 0.27 (SEM) pmol min-1 mm-1, a Michaelis constant (Km) of 0.20 +/- 0.07 mmol . l-1, and an apparent permeability coefficient of 0.27 +/- 0.11 pmol min-1 mm-1 (mmol . l-1)-1 (approximately 0.06 micrometer/s). The 35S concentration in the cell exceeded that in the lumen by almost 60-fold during the lumen-to-bath flux, and exceeded the bathing solution concentration by 4.7-fold during the bath-to-lumen flux. Thus cystine was accumulated by the cells across either membrane, but over 77% of the intracellular activity was in the form of cysteine. Although the presence of luminal L-lysine or cycloleucine inhibited the absorptive flux of cystine, neither amino acid affected the bath-to-lumen flux.
Collapse
|
19
|
Bosco E, Porta N, Diezi J. Renal handling of cadmium: a study by tubular microinjections. ARCHIVES OF TOXICOLOGY. SUPPLEMENT. = ARCHIV FUR TOXIKOLOGIE. SUPPLEMENT 1984; 7:371-3. [PMID: 6596003 DOI: 10.1007/978-3-642-69132-4_62] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
109Cadmium was microinjected, in different chemical forms, into the proximal or distal cortical tubules of adult rats and recovery in the pelvic urine from the ipsilateral kidney was measured. There was marked uptake of inorganic cadmium along the proximal tubules, and only negligible uptake in the distal nephron. The fractional uptake of the complex cadmium-cysteine in the proximal tubule was inversely related to the cysteine concentration. The chelate cadmium-pentetic acid was completely recovered in the pelvic urine.
Collapse
|
20
|
Stieger B, Stange G, Biber J, Murer H. Transport of L-cysteine by rat renal brush border membrane vesicles. J Membr Biol 1983; 73:25-37. [PMID: 6864766 DOI: 10.1007/bf01870338] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Brush border membranes were isolated from rat renal cortex by a divalent cation precipitation method. L-35S-cysteine uptake into the vesicles was measured by a rapid filtration method. Only minimal binding of the amino acid to the vesicles was observed. Sodium stimulates L-cysteine uptake specifically. Anion replacement experiments, experiments in the presence of potassium/valinomycin-induced diffusion potential as well as experiments with a potential-sensitive fluorescent dye document an electrogenic sodium-dependent uptake mechanism for L-cysteine. Tracer replacement experiments as well as the fluorescence experiments indicate a preferential transport of L-cysteine. Transport of L-cysteine is inhibited by L-alanine and L-phenylalanine but not by L-glutamic acid and the L-basic amino acids. Initial, linear influx kinetics provide evidence for the existence of two transport sites. The results suggest (a) sodium-dependent mechanism(s) for L-cysteine shared by other neutral amino acids.
Collapse
|
21
|
Völkl H, Silbernagl S. Reexamination of the interplay between dibasic amino acids and I-cystine/L-cysteine during tubular reabsorption. Pflugers Arch 1982; 395:196-200. [PMID: 7155793 DOI: 10.1007/bf00584809] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
UNLABELLED Interactions of L-cysteine (= cys) and L-cystine (= cys-cys), and dibasic amino acids were investigated during tubular reabsorption by microperfusion experiments in rat kidney. The following results were obtained: The dibasic amino acids L-ornithine and L-canavanine were strong inhibitors of cys-cys reabsorption. The arginine analogue agmatine and the lysine analogue 2,6-diaminopimelic acid had no effect. The oxidizing agent azodicarboxylic acid bis-dimethylamide (= diamide) decreased the fractional reabsorption rate (= FRR) of cys-cys (0.08 mmol X l-1) from 84% to 60% when present in the perfusion fluid in a concentration of 10 mmol X l-1. Diamide did not affect the reabsorption of a dibasic amino acid (L-arginine) nor of a neutral amino acid (L-phenylalanine). The FRR of L-arginine and L-ornithine could not be decreased by adding cys-cys to the perfusion fluid. Cys had just as little effect on the reabsorption of L-arginine like agmatine. In the presence of alpha-aminoisobutyric acid a slight reduction of the FRR of L-arginine could be observed. The dibasic amino acids L-arginine and L-canavanine had no influence on the FRR of cys when dithioerythritol was added to the perfusion fluid. CONCLUSIONS More than one site exists for tubular reabsorption of cys-cys. One of these may be shared by dibasic amino acids. Cys is reabsorbed by a separate and specific transport system. A reduction of cys-cys to cys takes place rather in the tubular cell than in the lumen.
Collapse
|