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Abad Baucells C, Schönauer R, Halbritter J. The genetics of cystinuria - an update and critical reevaluation. Curr Opin Nephrol Hypertens 2024; 33:231-237. [PMID: 38240263 DOI: 10.1097/mnh.0000000000000949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2024]
Abstract
PURPOSE OF REVIEW We aimed to critically evaluate how the establishment of genotype-based treatment for cystinuria has been hampered due to the large number of variants of unknown significance (VUS) within the disease causing genes as well as challenges in accessing a large enough sample size for systematic analysis of endpoint parameters that truly reflect disease severity. This review further discusses how to overcome these hurdles with the establishment of a cystinuria-specific refinement of the current American College of Medical Genetics and Genomics (ACMG)-criteria of variant interpretation. RECENT FINDINGS Novel tools such as AlphaMissense combined with the establishment of a refined ACMG criterion will play a significant role in classifying VUS within the responsible disease genes SLC3A1 (rBAT) and SLC7A9 (BAT1). This will also be essential in elucidating the role of promising candidate genes, such as SLC7A13 (AGT1), which have been derived from murine model systems and still need further research to determine if they are involved in human cystinuria. SUMMARY Cystinuria was one of the first disorders to receive a gene-based classification, nonetheless, the clinically actionable implications of genetic diagnostics is still minor. This is due to poorly characterized genotype-phenotype correlations which results in a lack of individualized (genotype-) based management and metaphylaxis.
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Affiliation(s)
- Clàudia Abad Baucells
- Department of Nephrology and Medical Intensive Care, Charité Universitätsmedizin Berlin, Berlin, Germany
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Prot-Bertoye C, Jung V, Tostivint I, Roger K, Benoist JF, Jannot AS, Van Straaten A, Knebelmann B, Guerrera IC, Courbebaisse M. Effect of urine alkalization on urinary inflammatory markers in cystinuric patients. Clin Kidney J 2024; 17:sfae040. [PMID: 38510798 PMCID: PMC10953617 DOI: 10.1093/ckj/sfae040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Indexed: 03/22/2024] Open
Abstract
Background Cystinuria is associated with a high prevalence of chronic kidney disease (CKD). We previously described a urinary inflammatory-protein signature (UIS), including 38 upregulated proteins, in cystinuric patients (Cys-patients), compared with healthy controls (HC). This UIS was higher in Cys-patients with CKD. In the present observational study, we aimed to investigate the UIS in Cys-patients without CKD and patients with calcium nephrolithiasis (Lith-patients), versus HC and the effect of urine alkalization on the UIS of Cys-patients. Methods UIS was evaluated by nano-liquid chromatography coupled to high-resolution mass spectrometry in adult HC, Lith-patients and non-treated Cys-patients with an estimated glomerular filtration rate >60 mL/min/1.73 m2, and after a 3-month conventional alkalizing treatment in Cys-patients. Results Twenty-one Cys-patients [12 men, median age (interquartile range) 30.0 (25.0-44.0) years], 12 Lith-patients [8 men, 46.2 (39.5-54.2) years] and 7 HC [2 men, 43.1 (31.0-53.9) years] were included. Among the 38 proteins upregulated in our previous work, 11 proteins were also upregulated in Cys-patients compared with HC in this study (5 circulating inflammatory proteins and 6 neutrophil-derived proteins). This UIS was also found in some Lith-patients. Using this UIS, we identified two subclusters of Cys-patients (5 with a very high/high UIS and 16 with a moderate/low UIS). In the Cys-patients with very high/high UIS, urine alkalization induced a significant decrease in urinary neutrophil-derived proteins. Conclusion A high UIS is present in some Cys-patients without CKD and decreases under alkalizing treatment. This UIS could be a prognostic marker to predict the evolution towards CKD in cystinuria.
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Affiliation(s)
- Caroline Prot-Bertoye
- Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Service de Physiologie – Explorations fonctionnelles, Paris, France
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université Paris Cité, Paris, France
- CNRS ERL 8228 – Laboratoire de Physiologie Rénale et Tubulopathies, Paris, France
- Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Paris, France
- Centre de Référence des Maladies Rares du Calcium et du Phosphate, Paris, France
- Association LUNNE Lithiases UriNaires Network, Paris, France
| | - Vincent Jung
- Proteomics Platform Necker, Université Paris Cité – Structure Fédérative de Recherche Necker, INSERM US24/CNRS UAR3633, Paris, France
| | - Isabelle Tostivint
- Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Paris, France
- Association LUNNE Lithiases UriNaires Network, Paris, France
- Assistance Publique-Hôpitaux de Paris, Hôpital de la Pitié Salpêtrière, Service de Néphrologie, Paris, France
- GRC 20 ARDELURO groupe de recherche clinique Analyse, Recherche, Développement et Evaluation en Endourologie et Lithiase Urinaire, Médecine Sorbonne Université, Paris, France
| | - Kevin Roger
- Proteomics Platform Necker, Université Paris Cité – Structure Fédérative de Recherche Necker, INSERM US24/CNRS UAR3633, Paris, France
| | - Jean-François Benoist
- Faculté de pharmacie, Université Paris Saclay, Orsay, France
- Assistance Publique-Hôpitaux de Paris, Hôpital Necker, Service de Biochimie métabolique, Paris, France
| | - Anne-Sophie Jannot
- Assistance Publique-Hôpitaux de Paris – Centre, Université Paris Cité, Hôpital Européen Georges Pompidou, Service d'informatique Médicale, Santé Publique et Biostatistiques, Paris, France. HeKA, Centre de recherche des Cordeliers, INSERM, INRIA, Paris, France
| | - Alexis Van Straaten
- Assistance Publique-Hôpitaux de Paris – Centre, Université Paris Cité, Hôpital Européen Georges Pompidou, Service d'informatique Médicale, Santé Publique et Biostatistiques, Paris, France. HeKA, Centre de recherche des Cordeliers, INSERM, INRIA, Paris, France
| | - Bertrand Knebelmann
- Faculté de médecine, Université Paris Cité, Paris, France
- Assistance Publique-Hôpitaux de Paris, Hôpital Necker, Service de Néphrologie, Paris, France
- INEM Unité Inserm U1151, Paris, France
| | - Ida Chiara Guerrera
- Proteomics Platform Necker, Université Paris Cité – Structure Fédérative de Recherche Necker, INSERM US24/CNRS UAR3633, Paris, France
| | - Marie Courbebaisse
- Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Service de Physiologie – Explorations fonctionnelles, Paris, France
- Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Paris, France
- Centre de Référence des Maladies Rares du Calcium et du Phosphate, Paris, France
- Association LUNNE Lithiases UriNaires Network, Paris, France
- Faculté de médecine, Université Paris Cité, Paris, France
- INEM Unité Inserm U1151, Paris, France
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Zafar R, Awais M. Molecular identification of missense variants in SLC3A1 gene; an approach leading to computer-aided drug design for cystinuria. Gene 2023; 888:147802. [PMID: 37716586 DOI: 10.1016/j.gene.2023.147802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2023] [Revised: 09/09/2023] [Accepted: 09/13/2023] [Indexed: 09/18/2023]
Abstract
Cystinuria is a rare congenital disorder characterized by the formation of cystine stones in urinary system, mainly kidneys and urinary tract. It follows the autosomal recessive inheritance pattern, where both of the parents contain the mutant allele. Cystine is an oxidized dimeric form of amino acid cysteine, shining crystal of greenish-yellow color sized greater than 5 mm. A minor genetic defect in SLC3A1 gene, downregulate the cystine transporter, rBAT protein, to absorb cystine and other dibasic amino acids in proximal tubule of nephron, causing Cystinuria. Computational and molecular analysis of SLC3A1 gene was performed to identify the deleterious missense single nucleotide variations (mSNVs) linked with Cystinuria in Pakistani population. In silico analysis of whole SLC3A1 gene nsSNPs has revealed that the exon 1, 6 and 10 are the hotspot areas, which potentially alter the protein structure and function. Three SNVs including one synonymous SNV A186C in exon 1, and two mSNVs including G314T in exon 1 and G44972A in exons 10 were identified. Both mSNVs were confirmed by ARMS PCR in all the 68 samples. The results have shown that 10% of the patients have G314T, 16% have G44972A and 74% of the patients have both of these mSNVs. Both of these mSNVs were involved in the structural and functional deterioration of rBAT protein. Additionally, computer aided drug designing tools were used to design diaminobenzylpyrimidine drug around the mutant residues which exhibit the lowest binding affinity with the target as compared to the previously reported cystine binding thiol drugs. In future, the present study could be extended to a large scale for mass screening of reported SNVs and mSNVs which, ultimately, lead to the development of knockouts for the functional studies and treatments.
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Affiliation(s)
- Rimsha Zafar
- Department of Biotechnology, Faculty of Science and Technology, University of Central Punjab, Lahore 54782, Pakistan.
| | - Muhammad Awais
- Department of Biotechnology, Faculty of Science and Technology, University of Central Punjab, Lahore 54782, Pakistan.
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Mayayo-Vallverdú C, Prat E, Vecino-Pérez M, González L, Gràcia-Garcia S, San Miguel L, Lopera N, Arias A, Artuch R, López de Heredia M, Torrecilla C, Rousaud-Barón F, Angerri O, Errasti-Murugarren E, Nunes V. Exploring the Contribution of the Transporter AGT1/rBAT in Cystinuria Progression: Insights from Mouse Models and a Retrospective Cohort Study. Int J Mol Sci 2023; 24:17140. [PMID: 38138969 PMCID: PMC10743100 DOI: 10.3390/ijms242417140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 11/25/2023] [Accepted: 12/03/2023] [Indexed: 12/24/2023] Open
Abstract
More than 20 years have passed since the identification of SLC3A1 and SLC7A9 as causative genes for cystinuria. However, cystinuria patients exhibit significant variability in the age of lithiasis onset, recurrence, and response to treatment, suggesting the presence of modulatory factors influencing cystinuria severity. In 2016, a second renal cystine transporter, AGT1, encoded by the SLC7A13 gene, was discovered. Although it was discarded as a causative gene for cystinuria, its possible effect as a modulatory gene remains unexplored. Thus, we analyzed its function in mouse models of cystinuria, screened the SLC7A13 gene in 34 patients with different lithiasic phenotypes, and functionally characterized the identified variants. Mice results showed that AGT1/rBAT may have a protective role against cystine lithiasis. In addition, among the four missense variants detected in patients, two exhibited a 25% impairment in AGT1/rBAT transport. However, no correlation between SLC7A13 genotypes and lithiasis phenotypes was observed in patients, probably because these variants were found in heterozygous states. In conclusion, our results, consistent with a previous study, suggest that AGT1/rBAT does not have a relevant effect on cystinuria patients, although an impact in patients carrying homozygous pathogenic variants cannot be discarded.
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Affiliation(s)
- Clara Mayayo-Vallverdú
- Human Molecular Genetics Laboratory, Gene, Disease and Therapy Program, Institut d’Investigació Biomèdica de Bellvitge (IDIBELL), 08908 L’Hospitalet de Llobregat, Spain; (C.M.-V.); (E.P.); (M.V.-P.); (L.G.); (M.L.d.H.)
- Genetics Section, Physiological Sciences Department, Health Sciences and Medicine Faculty, University of Barcelona, 08907 L’Hospitalet de Llobregat, Spain
| | - Esther Prat
- Human Molecular Genetics Laboratory, Gene, Disease and Therapy Program, Institut d’Investigació Biomèdica de Bellvitge (IDIBELL), 08908 L’Hospitalet de Llobregat, Spain; (C.M.-V.); (E.P.); (M.V.-P.); (L.G.); (M.L.d.H.)
- Genetics Section, Physiological Sciences Department, Health Sciences and Medicine Faculty, University of Barcelona, 08907 L’Hospitalet de Llobregat, Spain
| | - Marta Vecino-Pérez
- Human Molecular Genetics Laboratory, Gene, Disease and Therapy Program, Institut d’Investigació Biomèdica de Bellvitge (IDIBELL), 08908 L’Hospitalet de Llobregat, Spain; (C.M.-V.); (E.P.); (M.V.-P.); (L.G.); (M.L.d.H.)
| | - Laura González
- Human Molecular Genetics Laboratory, Gene, Disease and Therapy Program, Institut d’Investigació Biomèdica de Bellvitge (IDIBELL), 08908 L’Hospitalet de Llobregat, Spain; (C.M.-V.); (E.P.); (M.V.-P.); (L.G.); (M.L.d.H.)
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, 28029 Madrid, Spain (R.A.)
| | - Silvia Gràcia-Garcia
- Urinary Lithiasis Laboratory, Fundació Puigvert, 08025 Barcelona, Spain; (S.G.-G.); (N.L.)
| | - Luz San Miguel
- Urology Service, Fundació Puigvert, 08025 Barcelona, Spain; (L.S.M.); (F.R.-B.); (O.A.)
| | - Noelia Lopera
- Urinary Lithiasis Laboratory, Fundació Puigvert, 08025 Barcelona, Spain; (S.G.-G.); (N.L.)
| | - Angela Arias
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, 28029 Madrid, Spain (R.A.)
- Clinical Biochemistry Department, Institut de Recerca Sant Joan de Déu, Hospital Sant Joan de Déu, 08950 Esplugues de Llobregat, Spain
| | - Rafael Artuch
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, 28029 Madrid, Spain (R.A.)
- Clinical Biochemistry Department, Institut de Recerca Sant Joan de Déu, Hospital Sant Joan de Déu, 08950 Esplugues de Llobregat, Spain
| | - Miguel López de Heredia
- Human Molecular Genetics Laboratory, Gene, Disease and Therapy Program, Institut d’Investigació Biomèdica de Bellvitge (IDIBELL), 08908 L’Hospitalet de Llobregat, Spain; (C.M.-V.); (E.P.); (M.V.-P.); (L.G.); (M.L.d.H.)
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, 28029 Madrid, Spain (R.A.)
| | - Carlos Torrecilla
- Urology Service, Hospital Universitari de Bellvitge, 08908 L’Hospitalet de Llobregat, Spain;
| | - Ferran Rousaud-Barón
- Urology Service, Fundació Puigvert, 08025 Barcelona, Spain; (L.S.M.); (F.R.-B.); (O.A.)
| | - Oriol Angerri
- Urology Service, Fundació Puigvert, 08025 Barcelona, Spain; (L.S.M.); (F.R.-B.); (O.A.)
| | - Ekaitz Errasti-Murugarren
- Genetics Section, Physiological Sciences Department, Health Sciences and Medicine Faculty, University of Barcelona, 08907 L’Hospitalet de Llobregat, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, 28029 Madrid, Spain (R.A.)
| | - Virginia Nunes
- Human Molecular Genetics Laboratory, Gene, Disease and Therapy Program, Institut d’Investigació Biomèdica de Bellvitge (IDIBELL), 08908 L’Hospitalet de Llobregat, Spain; (C.M.-V.); (E.P.); (M.V.-P.); (L.G.); (M.L.d.H.)
- Genetics Section, Physiological Sciences Department, Health Sciences and Medicine Faculty, University of Barcelona, 08907 L’Hospitalet de Llobregat, Spain
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Sasaki H, Sasaki T, Hiura K, Watanabe M, Sasaki N. A mouse model of type B cystinuria due to spontaneous mutation in FVB/NJcl mice. Urolithiasis 2022; 50:679-684. [DOI: 10.1007/s00240-022-01356-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 08/15/2022] [Indexed: 10/15/2022]
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Zhang Z, Zheng R, Zhu C, Geng H, Xu G. Lipidomics characterization of the lipid metabolism profiles in a cystinuria rat model: Precalculus damage in the kidney of cystinuria. Prostaglandins Other Lipid Mediat 2022; 162:106651. [PMID: 35680078 DOI: 10.1016/j.prostaglandins.2022.106651] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Revised: 05/20/2022] [Accepted: 06/02/2022] [Indexed: 10/18/2022]
Abstract
Cystinuria is a genetic disorder of cystine transport, including defective protein b0,+AT (encoded by SLC7A9), and/or rBAT (encoded by SLC3A1). Patients present hyperexcretion of cystine in the urine, recurrent cystine lithiasis, and progressive decline in kidney function. Moreover, heterodimer transport is defective. To date, little omics data are accessible regarding this metabolic disease caused by membrane proteins. Since membrane function is closely related to changes in the lipidome, we decided to explore the changes in kidney tissue of a self-established cystinuria rat model by performing lipidomic analysis by LC-MS/MS. Our results demonstrated that Slc7a9 deficiency changed the lipid profile of the renal cortex and induced vital modifications in the lipidome, including major alterations in ChE, LPA, and PA. Among those alterations, this lipidomic study highlights the lipid changes that participate in inflammatory responses during cystinuria. As a result, lipid research, perhaps has great potential, for it may lead to the identification of novel therapeutic targets for the prevention and treatment of cystinuria.
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Affiliation(s)
- Zihan Zhang
- Shanghai Jiaotong University School of Medicine, China
| | - Rui Zheng
- Department of Pediatric Urology, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, China
| | - Caihua Zhu
- Shanghai Applied Protein Technology Co., Ltd., 201100, China
| | - Hongquan Geng
- Shanghai Jiaotong University School of Medicine, China; Department of Pediatric Urology, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, China.
| | - Guofeng Xu
- Shanghai Jiaotong University School of Medicine, China; Department of Pediatric Urology, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, China.
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Zhang Z, Zheng R, Chen Z, Zhan X, Fang X, Liu M, Li Y, Xu Y, Li D, Geng H, Zhang X, Xu G. Differences in renal cortex transcriptional profiling of wild-type and novel type B cystinuria model rats. Urolithiasis 2022. [PMID: 35416493 DOI: 10.1007/s00240-022-01321-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2021] [Accepted: 03/03/2022] [Indexed: 11/20/2022]
Abstract
Cystinuria is a genetic disorder of cystine transport that accounts for 1–2% of all cases of renal lithiasis. It is characterized by hyperexcretion of cystine in urine and recurrent cystine lithiasis. Defective transport of cystine into epithelial cells of renal tubules occurs because of mutations of the transport heterodimer, including protein b0,+AT (encoded by SLC7A9) and rBAT (encoded by SLC3A1) linked through a covalent disulfide bond. Study generated a novel type B cystinuria rat model by artificially deleting 7 bp of Slc7a9 gene exon 3 using the CRISPR-Cas9 system, and those Slc7a9-deficient rats were proved to be similar with cystinuria in terms of genome, transcriptome, translation, and biologic phenotypes with no off-target editing. Subsequent comparisons of renal histopathology indicated model rats gained typical secondary changes as medullary fibrosis with no stone formation. A total of 689 DEGs (383 upregulated and 306 downregulated) were differentially expressed in the renal cortex of cystinuria rats. In accordance with the functional annotation of DEGs, the potential role of glutathione metabolism processes in the kidney of cystinuria rat model was proposed, and KEGG analysis results showed that knock-out of Slc7a9 gene triggered more biological changes which has not been studied. In short, for the first time, a rat model and its transcriptional database that mimics the pathogenesis and clinical consequences of human type B cystinuria were generated.
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Ellingsen S, Narawane S, Fjose A, Verri T, Rønnestad I. The zebrafish cationic amino acid transporter/glycoprotein-associated family: sequence and spatiotemporal distribution during development of the transport system b 0,+ (slc3a1/slc7a9). Fish Physiol Biochem 2021; 47:1507-1525. [PMID: 34338990 PMCID: PMC8478756 DOI: 10.1007/s10695-021-00984-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Accepted: 06/29/2021] [Indexed: 06/12/2023]
Abstract
System b0,+ absorbs lysine, arginine, ornithine, and cystine, as well as some (large) neutral amino acids in the mammalian kidney and intestine. It is a heteromeric amino acid transporter made of the heavy subunit SLC3A1/rBAT and the light subunit SLC7A9/b0,+AT. Mutations in these two genes can cause cystinuria in mammals. To extend information on this transport system to teleost fish, we focused on the slc3a1 and slc7a9 genes by performing comparative and phylogenetic sequence analysis, investigating gene conservation during evolution (synteny), and defining early expression patterns during zebrafish (Danio rerio) development. Notably, we found that slc3a1 and slc7a9 are non-duplicated in the zebrafish genome. Whole-mount in situ hybridization detected co-localized expression of slc3a1 and slc7a9 in pronephric ducts at 24 h post-fertilization and in the proximal convoluted tubule at 3 days post-fertilization (dpf). Notably, both the genes showed co-localized expression in epithelial cells in the gut primordium at 3 dpf and in the intestine at 5 dpf (onset of exogenous feeding). Taken together, these results highlight the value of slc3a1 and slc7a9 as markers of zebrafish kidney and intestine development and show promise for establishing new zebrafish tools that can aid in the rapid screening(s) of substrates. Importantly, such studies will help clarify the complex interplay between the absorption of dibasic amino acids, cystine, and (large) neutral amino acids and the effect(s) of such nutrients on organismal growth.
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Affiliation(s)
- Ståle Ellingsen
- Department of Molecular Biology, University of Bergen, Postbox 7803, N-5020, Bergen, Norway
- Department of Biological Sciences, University of Bergen, Postbox 7803, N-5020, Bergen, Norway
| | - Shailesh Narawane
- Department of Molecular Biology, University of Bergen, Postbox 7803, N-5020, Bergen, Norway
| | - Anders Fjose
- Department of Molecular Biology, University of Bergen, Postbox 7803, N-5020, Bergen, Norway
- Department of Biological Sciences, University of Bergen, Postbox 7803, N-5020, Bergen, Norway
| | - Tiziano Verri
- Department of Biological and Environmental Sciences and Technologies, University of Salento, via Prov.le Lecce-Monteroni, 73100, Lecce, Italy
| | - Ivar Rønnestad
- Department of Biological Sciences, University of Bergen, Postbox 7803, N-5020, Bergen, Norway.
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Bai Y, Tang Y, Wang J, Wang X, Wang Z, Cao D, Han P, Wang J. Tolvaptan treatment of cystine urolithiasis in a mouse model of cystinuria. World J Urol 2020; 39:263-269. [PMID: 32189089 DOI: 10.1007/s00345-020-03166-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2019] [Accepted: 03/09/2020] [Indexed: 02/08/2023] Open
Abstract
INTRODUCTION Cystinuria is an inherited disease characterized by increased urinary cystine excretion and recurrent cystine stones. Current treatment regimens have limited effectiveness in preventing stone recurrence and are often poorly tolerated. The aim of this study was to evaluate the effect of tolvaptan, a vasopressin receptor 2 (V2) antagonist, on cystine stone volume in mice with cystinuria. MATERIALS AND METHODS Tolvaptan (0.4 mg per mouse) or placebo was delivered by gavage daily for 30 days. Urinary amino acids and cystine stones were analyzed to assess drug efficacy in preventing L-cystine stone growth using several analytical methods. Data were entered into SPSS and analyzed by paired sample T test. p value < 0.05 was considered significant. RESULTS Compared with control group, the liquid intake and urine volume in tolvaptan-treated mice were significantly increased. The urinary cystine concentrations in group tolvaptan was lower than the baseline concentration before the experiment. After treatment, mice treated with tolvaptan had significantly delayed stone growth, exhibited lower overall stone volume accumulation, compared with control group. The increased stone volume of tolvaptan group was less than control group (8.00 ± 4.93 mm3 vs 27.90 ± 4.48 mm3, p < 0.001). The serum creatinine in the control group (11.75 ± 1.634 μmol/L) was higher than that in the tolvaptan group (7.625 ± 1.401 μmol/L) (p = 0.0759). In addition, tolvaptan significantly inhibited the formation and growth of stones in mice after cystolithotomy. CONCLUSION The present study indicated that tolvaptan's efficacy in preventing L-cystine stone growth through increased liquid intake and urine volume of cystinuric mice.
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Affiliation(s)
- Yunjin Bai
- Department of Urology, West China Hospital, Sichuan University, Guoxue Xiang#37, Chengdu, 610041, Sichuan, China
| | - Yin Tang
- Department of Urology, West China Hospital, Sichuan University, Guoxue Xiang#37, Chengdu, 610041, Sichuan, China
| | - Jiahao Wang
- Department of Urology, West China Hospital, Sichuan University, Guoxue Xiang#37, Chengdu, 610041, Sichuan, China
| | - Xiaoming Wang
- Department of Urology, West China Hospital, Sichuan University, Guoxue Xiang#37, Chengdu, 610041, Sichuan, China
| | - Zhenghao Wang
- Department of Urology, West China Hospital, Sichuan University, Guoxue Xiang#37, Chengdu, 610041, Sichuan, China
| | - Dehong Cao
- Department of Urology, West China Hospital, Sichuan University, Guoxue Xiang#37, Chengdu, 610041, Sichuan, China
| | - Ping Han
- Department of Urology, West China Hospital, Sichuan University, Guoxue Xiang#37, Chengdu, 610041, Sichuan, China
| | - Jia Wang
- Department of Urology, West China Hospital, Sichuan University, Guoxue Xiang#37, Chengdu, 610041, Sichuan, China.
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Beckermann TM, Welch RC, Williams FM, Mortlock DP, Sha F, Ikizler TA, Woodard LE, Wilson MH. CRISPR/Cas9 engineering of albino cystinuria Type A mice. Genesis 2020; 58:e23357. [PMID: 32078250 DOI: 10.1002/dvg.23357] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 02/07/2020] [Accepted: 02/10/2020] [Indexed: 01/27/2023]
Abstract
Cystinuria Type A is a relatively common genetic kidney disease occurring in 1 in 7,000 people worldwide that results from mutation of the cystine transporter rBAT encoded by Slc3a1. We used CRISPR/Cas9 technology to engineer cystinuria Type A mice via genome editing of the C57BL/6NHsd background. These mice are an improvement on currently available models as they are on a coisogenic genetic background and have a single defined mutation. In order to use albinism to track Cas9 activity, we co-injected gRNAs targeting Slc3a1 and tyrosinase (Tyr) with Cas9 expressing plasmid DNA into mouse embryos. Two different Slc3a1 mutational alleles were derived, with homozygous mice of both demonstrating elevated urinary cystine levels, cystine crystals, and bladder stones. We used whole genome sequencing to evaluate for potential off-target editing. No off-target indels were observed for the top 10 predicted off-targets for Slc3a1 or Tyr. Therefore, we used CRISPR/Cas9 to generate coisogenic albino cystinuria Type A mice that could be used for in vivo imaging, further study, or developing new treatments of cystinuria.
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Affiliation(s)
- Thomas M Beckermann
- Department of Medicine, Division of Nephrology and Hypertension, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Richard C Welch
- Department of Medicine, Division of Nephrology and Hypertension, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Felisha M Williams
- Department of Medicine, Division of Nephrology and Hypertension, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Douglas P Mortlock
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Feng Sha
- Department of Medicine, Division of Nephrology and Hypertension, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Talat A Ikizler
- Department of Medicine, Division of Nephrology and Hypertension, Vanderbilt University Medical Center, Nashville, Tennessee.,Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Lauren E Woodard
- Department of Medicine, Division of Nephrology and Hypertension, Vanderbilt University Medical Center, Nashville, Tennessee.,Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee.,Department of Veterans Affairs, Tennessee Valley Health Services, Nashville, Tennessee
| | - Matthew H Wilson
- Department of Medicine, Division of Nephrology and Hypertension, Vanderbilt University Medical Center, Nashville, Tennessee.,Department of Veterans Affairs, Tennessee Valley Health Services, Nashville, Tennessee.,Department of Pharmacology, Vanderbilt University, Nashville, Tennessee
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Woodard LE, Welch RC, Veach RA, Beckermann TM, Sha F, Weinman EJ, Ikizler TA, Tischfield JA, Sahota A, Wilson MH. Metabolic consequences of cystinuria. BMC Nephrol 2019; 20:227. [PMID: 31221135 DOI: 10.1186/s12882-019-1417-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Accepted: 06/09/2019] [Indexed: 01/19/2023] Open
Abstract
Background Cystinuria is an inherited disorder of renal amino acid transport that causes recurrent nephrolithiasis and significant morbidity in humans. It has an incidence of 1 in 7000 worldwide making it one of the most common genetic disorders in man. We phenotypically characterized a mouse model of cystinuria type A resultant from knockout of Slc3a1. Methods Knockout of Slc3a1 at RNA and protein levels was evaluated using real-time quantitative PCR and immunofluorescence. Slc3a1 knockout mice were placed on normal or breeder chow diets and evaluated for cystine stone formation over time suing x-ray analysis, and the development of kidney injury by measuring injury biomarkers. Kidney injury was also evaluated via histologic analysis. Amino acid levels were measured in the blood of mice using high performance liquid chromatography. Liver glutathione levels were measured using a luminescent-based assay. Results We confirmed knockout of Slc3a1 at the RNA level, while Slc7a9 RNA representing the co-transporter was preserved. As expected, we observed bladder stone formation in Slc3a1−/− mice. Male Slc3a1−/− mice exhibited lower weights compared to Slc3a1+/+. Slc3a1−/− mice on a regular diet demonstrated elevated blood urea nitrogen (BUN) without elevation of serum creatinine. However, placing the knockout animals on a breeder chow diet, containing a higher cystine concentration, resulted in the development of elevation of both BUN and creatinine indicative of more severe chronic kidney disease. Histological examination revealed that these dietary effects resulted in worsened kidney tubular obstruction and interstitial inflammation as well as worsened bladder inflammation. Cystine is a precursor for the antioxidant molecule glutathione, so we evaluated glutathione levels in the livers of Slc3a1−/− mice. We found significantly lowered levels of both reduced and total glutathione in the knockout animals. Conclusions Our results suggest that that diet can affect the development and progression of chronic kidney disease in an animal model of cystinuria, which may have important implications for patients with this disease. Additionally, reduced glutathione may predispose those with cystinuria to injury caused by oxidative stress. Word count: 327. Electronic supplementary material The online version of this article (10.1186/s12882-019-1417-8) contains supplementary material, which is available to authorized users.
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Sahota A, Tischfield JA, Goldfarb DS, Ward MD, Hu L. Cystinuria: genetic aspects, mouse models, and a new approach to therapy. Urolithiasis 2019; 47:57-66. [PMID: 30515543 DOI: 10.1007/s00240-018-1101-7] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 11/27/2018] [Indexed: 01/07/2023]
Abstract
Cystinuria, a genetic disorder of cystine transport, is characterized by excessive excretion of cystine in the urine and recurrent cystine stones in the kidneys and, to a lesser extent, in the bladder. Males generally are more severely affected than females. The disorder may lead to chronic kidney disease in many patients. The cystine transporter (b0,+) is a heterodimer consisting of the rBAT (encoded by SLC3A1) and b0,+AT (encoded by SLC7A9) subunits joined by a disulfide bridge. The molecular basis of cystinuria is known in great detail, and this information is now being used to define genotype-phenotype correlations. Current treatments for cystinuria include increased fluid intake to increase cystine solubility and the administration of thiol drugs for more severe cases. These drugs, however, have poor patient compliance due to adverse effects. Thus, there is a need to reduce or eliminate the risks associated with therapy for cystinuria. Four mouse models for cystinuria have been described and these models provide a resource for evaluating the safety and efficacy of new therapies for cystinuria. We are evaluating a new approach for the treatment of cystine stones based on the inhibition of cystine crystal growth by cystine analogs. Our ongoing studies indicate that cystine diamides are effective in preventing cystine stone formation in the Slc3a1 knockout mouse model for cystinuria. In addition to crystal growth, crystal aggregation is required for stone formation. Male and female mice with cystinuria have comparable levels of crystalluria, but very few female mice form stones. The identification of factors that inhibit cystine crystal aggregation in female mice may provide insight into the gender difference in disease severity in patients with cystinuria.
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Vilches C, Boiadjieva-Knöpfel E, Bodoy S, Camargo S, López de Heredia M, Prat E, Ormazabal A, Artuch R, Zorzano A, Verrey F, Nunes V, Palacín M. Cooperation of Antiporter LAT2/CD98hc with Uniporter TAT1 for Renal Reabsorption of Neutral Amino Acids. J Am Soc Nephrol 2018; 29:1624-1635. [PMID: 29610403 DOI: 10.1681/asn.2017111205] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 02/24/2018] [Indexed: 01/01/2023] Open
Abstract
Background Reabsorption of amino acids (AAs) across the renal proximal tubule is crucial for intracellular and whole organism AA homeostasis. Although the luminal transport step is well understood, with several diseases caused by dysregulation of this process, the basolateral transport step is not understood. In humans, only cationic aminoaciduria due to malfunction of the basolateral transporter y+LAT1/CD98hc (SLC7A7/SLC3A2), which mediates the export of cationic AAs, has been described. Thus, the physiologic roles of basolateral transporters of neutral AAs, such as the antiporter LAT2/CD98hc (SLC7A8/SLC3A2), a heterodimer that exports most neutral AAs, and the uniporter TAT1 (SLC16A10), which exports only aromatic AAs, remain unclear. Functional cooperation between TAT1 and LAT2/CD98hc has been suggested by in vitro studies but has not been evaluated in vivoMethods To study the functional relationship of TAT1 and LAT2/CD98hc in vivo, we generated a double-knockout mouse model lacking TAT1 and LAT2, the catalytic subunit of LAT2/CD98hc (dKO LAT2-TAT1 mice).Results Compared with mice lacking only TAT1 or LAT2, dKO LAT2-TAT1 mice lost larger amounts of aromatic and other neutral AAs in their urine due to a tubular reabsorption defect. Notably, dKO mice also displayed decreased tubular reabsorption of cationic AAs and increased expression of y+LAT1/CD98hc.Conclusions The LAT2/CD98hc and TAT1 transporters functionally cooperate in vivo, and y+LAT1/CD98hc may compensate for the loss of LAT2/CD98hc and TAT1, functioning as a neutral AA exporter at the expense of some urinary loss of cationic AAs. Cooperative and compensatory mechanisms of AA transporters may explain the lack of basolateral neutral aminoacidurias in humans.
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Affiliation(s)
- Clara Vilches
- Molecular Genetics Laboratory, Genes Disease and Therapy Program, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Spain
| | - Emilia Boiadjieva-Knöpfel
- Department of Physiology.,Zurich Center for Integrative Human Physiology (ZIHP), and.,Swiss National Centre of Competence in Research (NCCR), Kidney Control of Homeostasis (Kidney.CH), University of Zurich, Zurich, Switzerland
| | - Susanna Bodoy
- Department of Biochemistry and Molecular Medicine, Biology Faculty, University of Barcelona, Barcelona, Spain.,Molecular Medicine Unit, Amino acid transporters and disease group, Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain
| | - Simone Camargo
- Department of Physiology.,Zurich Center for Integrative Human Physiology (ZIHP), and.,Swiss National Centre of Competence in Research (NCCR), Kidney Control of Homeostasis (Kidney.CH), University of Zurich, Zurich, Switzerland
| | - Miguel López de Heredia
- Molecular Genetics Laboratory, Genes Disease and Therapy Program, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER) - U730, U731, U703, and
| | - Esther Prat
- Molecular Genetics Laboratory, Genes Disease and Therapy Program, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER) - U730, U731, U703, and.,Genetics Section, Physiological Sciences Department, Health Sciences and Medicine Faculty, University of Barcelona, Barcelona, Spain; and
| | - Aida Ormazabal
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER) - U730, U731, U703, and.,Clinical Biochemistry Department, Institut de Recerca Sant Joan de Déu, Hospital Sant Joan de Déu, Esplugues de Llobregat, Spain
| | - Rafael Artuch
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER) - U730, U731, U703, and.,Clinical Biochemistry Department, Institut de Recerca Sant Joan de Déu, Hospital Sant Joan de Déu, Esplugues de Llobregat, Spain
| | - Antonio Zorzano
- Department of Biochemistry and Molecular Medicine, Biology Faculty, University of Barcelona, Barcelona, Spain.,Molecular Medicine Unit, Amino acid transporters and disease group, Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain.,Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM) - CB07/08/0017, Instituto de Salud Carlos III (ISCIII), Madrid, Spain
| | - François Verrey
- Department of Physiology.,Zurich Center for Integrative Human Physiology (ZIHP), and.,Swiss National Centre of Competence in Research (NCCR), Kidney Control of Homeostasis (Kidney.CH), University of Zurich, Zurich, Switzerland
| | - Virginia Nunes
- Molecular Genetics Laboratory, Genes Disease and Therapy Program, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Spain; .,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER) - U730, U731, U703, and.,Genetics Section, Physiological Sciences Department, Health Sciences and Medicine Faculty, University of Barcelona, Barcelona, Spain; and
| | - Manuel Palacín
- Department of Biochemistry and Molecular Medicine, Biology Faculty, University of Barcelona, Barcelona, Spain; .,Molecular Medicine Unit, Amino acid transporters and disease group, Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER) - U730, U731, U703, and
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Lehmphul I, Hoefig CS, Köhrle J. 3-Iodothyronamine reduces insulin secretion in vitro via a mitochondrial mechanism. Mol Cell Endocrinol 2018; 460:219-228. [PMID: 28754352 DOI: 10.1016/j.mce.2017.07.026] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 07/17/2017] [Accepted: 07/24/2017] [Indexed: 12/29/2022]
Abstract
PURPOSE 3-iodothyronamine (3-T1AM), a decarboxylated and deiodinated thyroid hormone metabolite, leads at pharmacological doses to hypoinsulinemia, hyperglucagonemia and hyperglycemia in vivo. As the pancreatic Langerhans islets express thyroid hormone transmembrane transporters (THTT), we tested the hypothesis that not only plasma membrane-mediated 3-T1AM binding to and activation of G-protein coupled receptors, but also 3-T1AM metabolite(s) generated by 3-T1AM uptake and metabolism might decrease glucose-stimulated insulin secretion (GSIS). METHODS Murine pancreatic β-cells MIN6 were characterized for gene expression of THTT, deiodinases and monoamine oxidases. 3-T1AM uptake and intracellular metabolism to the corresponding 3-iodothyroacetic acid were analysed by liquid-chromatography tandem mass spectrometry (LC-MS/MS) at different time points in cells as well as the conditioned medium. Mitochondrial activity, especially ATP-production, was monitored real-time after 3-T1AM application using Seahorse Bioanalyzer technique. Effect of 3-T1AM on GSIS into the culture medium was assayed by ELISA. RESULTS MIN6 cells express classical THTT, proposed to transport 3-T1AM, as well as 3-T1AM metabolizing enzymes comparable to murine primary pancreatic islets. 3-T1AM accumulates in MIN6 cells and is metabolized by intracellular MaoB to 3-iodothyroacetic, which in turn is rapidly exported. 3-T1AM decreases mitochondrial ATP-production concentration dependently. GSIS is diminished by 3-T1AM treatment. Using LC-MS/MS, no further 3-T1AM metabolites except 3-iodothyroacetic were detectable. CONCLUSIONS This data provides a first link between cellular 3-T1AM uptake and regulation of mitochondrial energy metabolism in ß-cells, resulting in reduced insulin secretion. We conclude that MIN6 is an appropriate cell model to study 3-T1AM-dependent (intra-)cellular biochemical mechanisms affecting insulin production in vitro.
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Affiliation(s)
- Ina Lehmphul
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Institut für Experimentelle Endokrinologie, 13353 Berlin, Germany
| | - Carolin S Hoefig
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Institut für Experimentelle Endokrinologie, 13353 Berlin, Germany
| | - Josef Köhrle
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Institut für Experimentelle Endokrinologie, 13353 Berlin, Germany.
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Hilton S, Mizukami K, Giger U. [Cystinuria caused by a SLC7A9 missense mutation in Siamese-crossbred littermates in Germany]. Tierarztl Prax Ausg K Kleintiere Heimtiere 2017; 45:265-272. [PMID: 28585658 DOI: 10.15654/tpk-160975] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 12/29/2016] [Indexed: 11/13/2022]
Abstract
Cystinuria is caused by defective proximal renal tubular reabsorption of the amino acids cystine, ornithine, lysine, and arginine (COLA). The low solubility of cystine in mildly acidic urine may lead to the formation of urinary cystine crystals and uroliths. Much progress has been made recently in the diagnosis and understanding of cystinuria in companion animals. In cats, cystinuria affects equally both genders independent of neutering status and, despite being rare, already more cystinuria-causing mutations have been detected in cats compared to dogs. In this study a litter of Siamese-crossbred cats in Germany was assessed clinically for cystinuria and screened for mutations known to cause cystinuria in cats. An adult male castrated cat was presented with cystine crystalluria and calculi-related urinary obstruction and treated with perineal urethrostomy, cystotomy, and medical management. This cat and a neutered male littermate without evidence of urinary tract disease were found to be positive for cystine by urinary nitroprusside test, to have increased urinary COLA values and to be homozygous for the p.Val294Glu mutation in the SLC7A9 gene coding for b0,+AT subunit of the b0,+ renal COLA transporter. Another littermate was non-cystinuric and did not carry this mutation. The same SLC7A9 mutation was previously found in a Maine coon, a Sphinx and a medium-haired cat in North America suggesting a common ancestor and likely first widespread SLC7A9 mutation causing cystinuria in cats. Genetic screening for this mutation may offer a simple and precise mean to diagnose other cats for cystinuria and offer specific management.
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Affiliation(s)
- Stephanie Hilton
- Prof. Dr. U. Giger, Ryan Veterinary Hospital, 3900 Delancey Street, Philadelphia, PA 19104-6010, USA,
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16
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Abstract
Cystinuria is a classical inborn error of metabolism characterized by a selective proximal renal tubular defect affecting cystine, ornithine, lysine, and arginine (COLA) reabsorption, which can lead to uroliths and urinary obstruction. In humans, dogs and mice, cystinuria is caused by variants in one of two genes, SLC3A1 and SLC7A9, which encode the rBAT and bo,+AT subunits of the bo,+ basic amino acid transporter system, respectively. In this study, exons and flanking regions of the SLC3A1 and SLC7A9 genes were sequenced from genomic DNA of cats (Felis catus) with COLAuria and cystine calculi. Relative to the Felis catus-6.2 reference genome sequence, DNA sequences from these affected cats revealed 3 unique homozygous SLC7A9 missense variants: one in exon 5 (p.Asp236Asn) from a non-purpose-bred medium-haired cat, one in exon 7 (p.Val294Glu) in a Maine Coon and a Sphinx cat, and one in exon 10 (p.Thr392Met) from a non-purpose-bred long-haired cat. A genotyping assay subsequently identified another cystinuric domestic medium-haired cat that was homozygous for the variant originally identified in the purebred cats. These missense variants result in deleterious amino acid substitutions of highly conserved residues in the bo,+AT protein. A limited population survey supported that the variants found were likely causative. The remaining 2 sequenced domestic short-haired cats had a heterozygous variant at a splice donor site in intron 10 and a homozygous single nucleotide variant at a branchpoint in intron 11 of SLC7A9, respectively. This study identifies the first SLC7A9 variants causing feline cystinuria and reveals that, as in humans and dogs, this disease is genetically heterogeneous in cats.
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Affiliation(s)
- Keijiro Mizukami
- Section of Medical Genetics, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
| | - Karthik Raj
- Section of Medical Genetics, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
| | - Carl Osborne
- Veterinary Clinical Sciences, College of Veterinary Medicine, University of Minnesota, Saint Paul, MN, United States of America
| | - Urs Giger
- Section of Medical Genetics, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
- * E-mail:
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Lee MH, Sahota A, Ward MD, Goldfarb DS. Cystine growth inhibition through molecular mimicry: a new paradigm for the prevention of crystal diseases. Curr Rheumatol Rep 2016; 17:33. [PMID: 25874348 DOI: 10.1007/s11926-015-0510-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cystinuria is a genetic disease marked by recurrent kidney stone formation, usually at a young age. It frequently leads to chronic kidney disease. Treatment options for cystinuria have been limited despite comprehensive understanding of its genetic pathophysiology. Currently available therapies suffer from either poor clinical adherence to the regimen or potentially serious adverse effects. Recently, we employed atomic force miscopy (AFM) to identify L-cystine dimethylester (CDME) as an effective molecular imposter of L-cystine, capable of inhibiting crystal growth in vitro. More recently, we demonstrated CDME's efficacy in inhibiting L-cystine crystal growth in vivo utilizing a murine model of cystinuria. The application of AFM to discover inhibitors of crystal growth through structural mimicry suggests a novel approach to preventing and treating crystal diseases.
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Nagamori S, Wiriyasermkul P, Guarch ME, Okuyama H, Nakagomi S, Tadagaki K, Nishinaka Y, Bodoy S, Takafuji K, Okuda S, Kurokawa J, Ohgaki R, Nunes V, Palacín M, Kanai Y. Novel cystine transporter in renal proximal tubule identified as a missing partner of cystinuria-related plasma membrane protein rBAT/SLC3A1. Proc Natl Acad Sci U S A 2016; 113:775-80. [PMID: 26739563 DOI: 10.1073/pnas.1519959113] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Heterodimeric amino acid transporters play crucial roles in epithelial transport, as well as in cellular nutrition. Among them, the heterodimer of a membrane protein b(0,+)AT/SLC7A9 and its auxiliary subunit rBAT/SLC3A1 is responsible for cystine reabsorption in renal proximal tubules. The mutations in either subunit cause cystinuria, an inherited amino aciduria with impaired renal reabsorption of cystine and dibasic amino acids. However, an unsolved paradox is that rBAT is highly expressed in the S3 segment, the late proximal tubules, whereas b(0,+)AT expression is highest in the S1 segment, the early proximal tubules, so that the presence of an unknown partner of rBAT in the S3 segment has been proposed. In this study, by means of coimmunoprecipitation followed by mass spectrometry, we have found that a membrane protein AGT1/SLC7A13 is the second partner of rBAT. AGT1 is localized in the apical membrane of the S3 segment, where it forms a heterodimer with rBAT. Depletion of rBAT in mice eliminates the expression of AGT1 in the renal apical membrane. We have reconstituted the purified AGT1-rBAT heterodimer into proteoliposomes and showed that AGT1 transports cystine, aspartate, and glutamate. In the apical membrane of the S3 segment, AGT1 is suggested to locate itself in close proximity to sodium-dependent acidic amino acid transporter EAAC1 for efficient functional coupling. EAAC1 is proposed to take up aspartate and glutamate released into luminal fluid by AGT1 due to its countertransport so that preventing the urinary loss of aspartate and glutamate. Taken all together, AGT1 is the long-postulated second cystine transporter in the S3 segment of proximal tubules and a possible candidate to be involved in isolated cystinuria.
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Espino M, Font-Llitjós M, Vilches C, Salido E, Prat E, López de Heredia M, Palacín M, Nunes V. Digenic Inheritance in Cystinuria Mouse Model. PLoS One 2015; 10:e0137277. [PMID: 26359869 DOI: 10.1371/journal.pone.0137277] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Accepted: 08/16/2015] [Indexed: 11/19/2022] Open
Abstract
Cystinuria is an aminoaciduria caused by mutations in the genes that encode the two subunits of the amino acid transport system b0,+, responsible for the renal reabsorption of cystine and dibasic amino acids. The clinical symptoms of cystinuria relate to nephrolithiasis, due to the precipitation of cystine in urine. Mutations in SLC3A1, which codes for the heavy subunit rBAT, cause cystinuria type A, whereas mutations in SLC7A9, which encodes the light subunit b0,+AT, cause cystinuria type B. By crossing Slc3a1-/- with Slc7a9-/- mice we generated a type AB cystinuria mouse model to test digenic inheritance of cystinuria. The 9 genotypes obtained have been analyzed at early (2- and 5-months) and late stage (8-months) of the disease. Monitoring the lithiasic phenotype by X-ray, urine amino acid content analysis and protein expression studies have shown that double heterozygous mice (Slc7a9+/-Slc3a1+/-) present lower expression of system b0,+ and higher hyperexcretion of cystine than single heterozygotes (Slc7a9+/-Slc3a1+/+ and Slc7a9+/+Slc3a1+/-) and give rise to lithiasis in 4% of the mice, demonstrating that cystinuria has a digenic inheritance in this mouse model. Moreover in this study it has been demonstrated a genotype/phenotype correlation in type AB cystinuria mouse model providing new insights for further molecular and genetic studies of cystinuria patients.
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Mizukami K, Raj K, Giger U. Feline cystinuria caused by a missense mutation in the SLC3A1 gene. J Vet Intern Med 2014; 29:120-5. [PMID: 25417848 PMCID: PMC4858075 DOI: 10.1111/jvim.12501] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Revised: 09/17/2014] [Accepted: 10/13/2014] [Indexed: 11/29/2022] Open
Abstract
Background Cystinuria is an inherited metabolic disease that is relatively common in dogs, but rare in cats and is characterized by defective amino acid reabsorption, leading to cystine urolithiasis. Objectives The aim of this study was to report on a mutation in a cystinuric cat. Animals A male domestic shorthair (DSH) cat with cystine calculi, 11 control cats from Wyoming, and 54 DSH and purebred control cats from elsewhere in the United States. Methods Exons of the SLC3A1 gene were sequenced from genomic DNA of the cystinuric cat and a healthy cat. Genetic screening for the discovered polymorphisms was conducted on all cats. Results A DSH cat showed stranguria beginning at 2 months of age, and cystine calculi were removed at 4 months of age. The cat was euthanized at 6 months of age because of neurological signs possibly related to arginine deficiency. Twenty‐five SLC3A1 polymorphisms were observed in the sequenced cats when compared to the feline reference sequence. The cystinuric cat was homozygous for 5 exonic and 8 noncoding SLC3A1 polymorphisms, and 1 of them was a unique missense mutation (c.1342C>T). This mutation results in a deleterious amino acid substitution (p.Arg448Trp) of a highly conserved arginine residue in the rBAT protein encoded by the SLC3A1 gene. This mutation was found previously in cystinuric human patients, but was not seen in any other tested cats. Conclusions and Clinical Importance This study is the first report of an SLC3A1 mutation causing cystinuria in a cat, and could be used to characterize other cystinuric cats at the molecular level.
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Affiliation(s)
- K Mizukami
- Section of Medical Genetics, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA
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Sahota A, Parihar JS, Capaccione KM, Yang M, Noll K, Gordon D, Reimer D, Yang I, Buckley BT, Polunas M, Reuhl KR, Lewis MR, Ward MD, Goldfarb DS, Tischfield JA. Novel cystine ester mimics for the treatment of cystinuria-induced urolithiasis in a knockout mouse model. Urology 2014; 84:1249.e9-15. [PMID: 25443947 DOI: 10.1016/j.urology.2014.07.043] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Revised: 07/03/2014] [Accepted: 07/24/2014] [Indexed: 11/27/2022]
Abstract
OBJECTIVE To assess the effectiveness of l-cystine dimethyl ester (CDME), an inhibitor of cystine crystal growth, for the treatment of cystine urolithiasis in an Slc3a1 knockout mouse model of cystinuria. MATERIALS AND METHODS CDME (200 μg per mouse) or water was delivered by gavage daily for 4 weeks. Higher doses by gavage or in the water supply were administered to assess organ toxicity. Urinary amino acids and cystine stones were analyzed to assess drug efficacy using several analytical methods. RESULTS Treatment with CDME led to a significant decrease in stone size compared with that of the water group (P = .0002), but the number of stones was greater (P = .005). The change in stone size distribution between the 2 groups was evident by micro computed tomography. Overall, cystine excretion in urine was the same between the 2 groups (P = .23), indicating that CDME did not interfere with cystine metabolism. Scanning electron microscopy analysis of cystine stones from the CDME group demonstrated a change in crystal habit, with numerous small crystals. l-cysteine methyl ester was detected by ultra-performance liquid chromatography-mass spectrometer in stones from the CDME group only, indicating that a CDME metabolite was incorporated into the crystal structure. No pathologic changes were observed at the doses tested. CONCLUSION These data demonstrate that CDME promotes formation of small stones but does not prevent stone formation, consistent with the hypothesis that CDME inhibits cystine crystal growth. Combined with the lack of observed adverse effects, our findings support the use of CDME as a viable treatment for cystine urolithiasis.
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Affiliation(s)
- Amrik Sahota
- Department of Genetics, Rutgers University, Piscataway, NJ.
| | - Jaspreet S Parihar
- Division of Urology, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ
| | | | - Min Yang
- Department of Genetics, Rutgers University, Piscataway, NJ
| | - Kelsey Noll
- Department of Genetics, Rutgers University, Piscataway, NJ
| | - Derek Gordon
- Department of Genetics, Rutgers University, Piscataway, NJ
| | - David Reimer
- Laboratory Animal Services, Rutgers University, Piscataway, NJ
| | - Ill Yang
- Environmental and Occupational Health Sciences Institute, Rutgers University, Piscataway, NJ
| | - Brian T Buckley
- Environmental and Occupational Health Sciences Institute, Rutgers University, Piscataway, NJ
| | - Marianne Polunas
- Environmental and Occupational Health Sciences Institute, Rutgers University, Piscataway, NJ
| | - Kenneth R Reuhl
- Environmental and Occupational Health Sciences Institute, Rutgers University, Piscataway, NJ
| | - Matthew R Lewis
- Department of Surgery and Cancer, Imperial College London, London, United Kingdom
| | - Michael D Ward
- Department of Chemistry, New York University, New York, NY
| | - David S Goldfarb
- Nephrology Division, New York University Langone Medical Center, New York, NY
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Livrozet M, Vandermeersch S, Mesnard L, Thioulouse E, Jaubert J, Boffa JJ, Haymann JP, Baud L, Bazin D, Daudon M, Letavernier E. An animal model of type A cystinuria due to spontaneous mutation in 129S2/SvPasCrl mice. PLoS One 2014; 9:e102700. [PMID: 25048459 PMCID: PMC4105406 DOI: 10.1371/journal.pone.0102700] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Accepted: 06/21/2014] [Indexed: 11/19/2022] Open
Abstract
Cystinuria is an autosomal recessive disease caused by the mutation of either SLC3A1 gene encoding for rBAT (type A cystinuria) or SLC7A9 gene encoding for b0,+AT (type B cystinuria). Here, we evidenced in a commonly used congenic 129S2/SvPasCrl mouse substrain a dramatically high frequency of kidney stones that were similar to those of patients with cystinuria. Most of 129S2/SvPasCrl exhibited pathognomonic cystine crystals in urine and an aminoaciduria profile similar to that of patients with cystinuria. In addition, we observed a heterogeneous inflammatory infiltrate and cystine tubular casts in the kidney of cystinuric mice. As compared to another classical mouse strain, C57BL/6J mice, 129S2/SvPasCrl mice had an increased mortality associated with bilateral obstructive hydronephrosis. In 129S2/SvPasCrl mice, the heavy subunit rBAT of the tetrameric transporter of dibasic amino acids was absent in proximal tubules and we identified a single pathogenic mutation in a highly conserved region of the Slc3a1 gene. This novel mouse model mimicking human disease would allow us further pathophysiological studies and may be useful to analyse the crystal/tissue interactions in cystinuria.
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Affiliation(s)
- Marine Livrozet
- Sorbonne Universités, UPMC Univ Paris 06, UMR S 702, Paris, France
- INSERM, UMR S 702, Paris, France
| | - Sophie Vandermeersch
- Sorbonne Universités, UPMC Univ Paris 06, UMR S 702, Paris, France
- INSERM, UMR S 702, Paris, France
| | - Laurent Mesnard
- Department of Physiology and Biophysics, Cornell University, Ithaca, New York, United States of America
| | | | - Jean Jaubert
- Institut Pasteur, Mouse Functional Genetics Unit, Paris, France
- CNRS URA 2578, Paris, France
| | - Jean-Jacques Boffa
- Sorbonne Universités, UPMC Univ Paris 06, UMR S 702, Paris, France
- INSERM, UMR S 702, Paris, France
- Néphrologie, AP-HP, Hôpital Tenon, Paris, France
| | - Jean-Philippe Haymann
- Sorbonne Universités, UPMC Univ Paris 06, UMR S 702, Paris, France
- INSERM, UMR S 702, Paris, France
- Explorations Fonctionnelles Multidisciplinaires, AP-HP, Hôpital Tenon, Paris, France
| | - Laurent Baud
- Sorbonne Universités, UPMC Univ Paris 06, UMR S 702, Paris, France
- INSERM, UMR S 702, Paris, France
- Explorations Fonctionnelles Multidisciplinaires, AP-HP, Hôpital Tenon, Paris, France
| | - Dominique Bazin
- CNRS-LCMCP- Sorbonne Universités UPMC Univ Paris 06, Collège de France, Paris, France
| | - Michel Daudon
- Sorbonne Universités, UPMC Univ Paris 06, UMR S 702, Paris, France
- INSERM, UMR S 702, Paris, France
- Explorations Fonctionnelles Multidisciplinaires, AP-HP, Hôpital Tenon, Paris, France
| | - Emmanuel Letavernier
- Sorbonne Universités, UPMC Univ Paris 06, UMR S 702, Paris, France
- INSERM, UMR S 702, Paris, France
- Explorations Fonctionnelles Multidisciplinaires, AP-HP, Hôpital Tenon, Paris, France
- * E-mail:
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Abstract
PURPOSE OF REVIEW Cystinuria is a rare genetic disease with increased urinary excretion of the poorly soluble amino acid cystine. It can lead to significant morbidity in affected patients due to the often large and recurrent resulting kidney stones. Treatment is focused on the prevention of stone formation. There have been few advances in the available therapeutic options for the disorder in the last 15-20 years. RECENT FINDINGS Although no new treatments have emerged in the prevention of cystinuria in recent years, several developments hold promise for advancing the field of caring for affected patients. A new method of measuring urinary cystine and estimating potential for stone formation, called cystine capacity, may prove to be a useful tool in monitoring the disease. The discoveries of the mutations that cause cystinuria have led to a new classification system based on genotype that is more accurate than the prior phenotypic one. The finding of new compounds that inhibit cystine crystal growth in vitro, now being tested in animal models, may lead to new potential therapies in years to come. The Rare Kidney Stone Consortium has developed a registry and hopes to lead further efforts in dealing with cystinuria. SUMMARY With several recent advances in the monitoring and treatment of cystinuria, and the gathering of clinical patient data, there are now opportunities for new management protocols and therapies.
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Giacopo AD, Rubio-Aliaga I, Cantone A, Artunc F, Rexhepaj R, Frey-Wagner I, Font-Llitjós M, Gehring N, Stange G, Jaenecke I, Mohebbi N, Closs EI, Palacín M, Nunes V, Daniel H, Lang F, Capasso G, Wagner CA. Differential cystine and dibasic amino acid handling after loss of function of the amino acid transporter b0,+AT (Slc7a9) in mice. Am J Physiol Renal Physiol 2013; 305:F1645-55. [DOI: 10.1152/ajprenal.00221.2013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cystinuria is an autosomal recessive disease caused by mutations in SLC3A1 ( rBAT) and SLC7A9 ( b 0,+ AT). Gene targeting of the catalytic subunit ( Slc7a9) in mice leads to excessive excretion of cystine, lysine, arginine, and ornithine. Here, we studied this non-type I cystinuria mouse model using gene expression analysis, Western blotting, clearance, and brush-border membrane vesicle (BBMV) uptake experiments to further characterize the renal and intestinal consequences of losing Slc7a9 function. The electrogenic and BBMV flux studies in the intestine suggested that arginine and ornithine are transported via other routes apart from system b0,+. No remarkable gene expression changes were observed in other amino acid transporters and the peptide transporters in the intestine and kidney. Furthermore, the glomerular filtration rate (GFR) was reduced by 30% in knockout animals compared with wild-type animals. The fractional excretion of arginine was increased as expected (∼100%), but fractional excretions of lysine (∼35%), ornithine (∼16%), and cystine (∼11%) were less affected. Loss of function of b0,+AT reduced transport of cystine and arginine in renal BBMVs and completely abolished the exchanger activity of dibasic amino acids with neutral amino acids. In conclusion, loss of Slc7a9 function decreases the GFR and increases the excretion of several amino acids to a lesser extent than expected with no clear regulation at the mRNA and protein level of alternative transporters and no increased renal epithelial uptake. These observations indicate that transporters located in distal segments of the kidney and/or metabolic pathways may partially compensate for Slc7a9 loss of function.
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Affiliation(s)
- Andrea Di Giacopo
- Institute of Physiology-Zürich Center for Integrative Human Physiology (ZIHP), University of Zürich, Zürich, Switzerland
| | - Isabel Rubio-Aliaga
- Institute of Physiology-Zürich Center for Integrative Human Physiology (ZIHP), University of Zürich, Zürich, Switzerland
| | - Alessandra Cantone
- Department of Internal Medicine, Chair of Nephrology, Second University of Naples, Naples, Italy
| | - Ferruh Artunc
- Department of Physiology, University of Tübingen, Tübingen, Germany
| | - Rexhep Rexhepaj
- Department of Physiology, University of Tübingen, Tübingen, Germany
| | | | - Mariona Font-Llitjós
- Medical and Molecular Genetics Center, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Spain
- U730 CIBERER, Barcelona, Spain
| | - Nicole Gehring
- Institute of Physiology-Zürich Center for Integrative Human Physiology (ZIHP), University of Zürich, Zürich, Switzerland
| | - Gerti Stange
- Institute of Physiology-Zürich Center for Integrative Human Physiology (ZIHP), University of Zürich, Zürich, Switzerland
| | - Isabel Jaenecke
- Department of Pharmacology, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - Nilufar Mohebbi
- Institute of Physiology-Zürich Center for Integrative Human Physiology (ZIHP), University of Zürich, Zürich, Switzerland
| | - Ellen I. Closs
- Department of Pharmacology, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - Manuel Palacín
- IRB Barcelona, Department of Biochemistry and Molecular Biology, University of Barcelona and U731 CIBERER, Barcelona, Spain
| | - Virginia Nunes
- Medical and Molecular Genetics Center, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Spain
- Department of Physiological Sciences II, University of Barcelona, Spain; and
- U730 CIBERER, Barcelona, Spain
| | - Hannelore Daniel
- Molecular Nutrition Unit, Technical University of Munich, Freising, Germany
| | - Florian Lang
- Department of Physiology, University of Tübingen, Tübingen, Germany
| | - Giovambattista Capasso
- Department of Internal Medicine, Chair of Nephrology, Second University of Naples, Naples, Italy
| | - Carsten A. Wagner
- Institute of Physiology-Zürich Center for Integrative Human Physiology (ZIHP), University of Zürich, Zürich, Switzerland
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Fotiadis D, Kanai Y, Palacín M. The SLC3 and SLC7 families of amino acid transporters. Mol Aspects Med 2013; 34:139-58. [PMID: 23506863 DOI: 10.1016/j.mam.2012.10.007] [Citation(s) in RCA: 450] [Impact Index Per Article: 40.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Accepted: 08/15/2012] [Indexed: 01/18/2023]
Abstract
Amino acids are necessary for all living cells and organisms. Specialized transporters mediate the transfer of amino acids across plasma membranes. Malfunction of these proteins can affect whole-body homoeostasis giving raise to diverse human diseases. Here, we review the main features of the SLC3 and SLC7 families of amino acid transporters. The SLC7 family is divided into two subfamilies, the cationic amino acid transporters (CATs), and the L-type amino acid transporters (LATs). The latter are the light or catalytic subunits of the heteromeric amino acid transporters (HATs), which are associated by a disulfide bridge with the heavy subunits 4F2hc or rBAT. These two subunits are glycoproteins and form the SLC3 family. Most CAT subfamily members were functionally characterized and shown to function as facilitated diffusers mediating the entry and efflux of cationic amino acids. In certain cells, CATs play an important role in the delivery of L-arginine for the synthesis of nitric oxide. HATs are mostly exchangers with a broad spectrum of substrates and are crucial in renal and intestinal re-absorption and cell redox balance. Furthermore, the role of the HAT 4F2hc/LAT1 in tumor growth and the application of LAT1 inhibitors and PET tracers for reduction of tumor progression and imaging of tumors are discussed. Finally, we describe the link between specific mutations in HATs and the primary inherited aminoacidurias, cystinuria and lysinuric protein intolerance.
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Popovska-Jankovic K, Tasic V, Bogdanovic R, Miljkovic P, Golubovic E, Soylu A, Saraga M, Pavicevic S, Baskin E, Akil I, Gregoric A, Lilova M, Topaloglu R, Sukarova Stefanovska E, Plaseska-Karanfilska D. Molecular characterization of cystinuria in south-eastern European countries. Urolithiasis 2012; 41:21-30. [PMID: 23532419 DOI: 10.1007/s00240-012-0531-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Accepted: 12/08/2012] [Indexed: 10/27/2022]
Abstract
Cystinuria is an autosomal recessive disorder caused by defective transport of cystine and dibasic amino acids in the proximal renal tubules and small intestine. So far, more than 128 mutations in SLC3A1 gene, and 93 in SLC7A9 gene have been described as a cause of cystinuria. We present a molecular characterization of the cystinuria in 47 unrelated south-east European families. The molecular methodology included direct sequencing, single strand conformational polymorphism, and restriction fragment length polymorphism. A total of 93 (94.9 %) out of 98 unrelated cystinuric chromosomes have been characterized. Mutations in SLC3A1 gene account for 64.3 % and in SLC7A9 gene for 30.6 % of the cystinuric chromosomes. Ten different mutations in SLC3A1 gene were found, and two of them were novel (C242R and L573X), while in SLC7A9 gene seven mutations were found, of which three were novel (G73R, V375I and c.1048_1051delACTC). The most common mutations in this study were T216M (24.5 %), M467T (16.3 %) and R365L (11.2 %) in SLC3A1 and G105R (21.4 %) in SLC7A9 gene. A population specificity of cystinuria mutations was observed; T216M mutation was the only mutation present among Gypsies, G105R was the most common mutation among Albanians and Macedonians, and R365L among Serbs. The results of this study allowed introduction of rapid, simple and cost-effective genetic diagnosis of cystinuria that enables an early preventive care of affected patients and a prenatal diagnosis in affected families.
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Affiliation(s)
- Katerina Popovska-Jankovic
- Macedonian Academy of Science and Arts, Research Centre for Genetic Engineering and Biotechnology "Georgi D. Efremov", 1000, Skopje, Republic of Macedonia
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Bodoy S, Fotiadis D, Stoeger C, Kanai Y, Palacín M. The small SLC43 family: facilitator system l amino acid transporters and the orphan EEG1. Mol Aspects Med 2012; 34:638-45. [PMID: 23268354 DOI: 10.1016/j.mam.2012.12.006] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Accepted: 12/04/2012] [Indexed: 11/26/2022]
Abstract
The SLC43 family is composed of only three genes coding for the plasma membrane facilitator system l amino acid transporters LAT3 (SLC43A1; TC 2.A.1.44.1) and LAT4 (SLC43A2; TC 2.A.1.44.2), and the orphan protein EEG1 (SLC43A3; TC 2.A.1.44.3). Besides the known mechanism of transport of LAT3 and LAT4, their physiological roles still remain quite obscure. Morphants suggested a role of LAT3 in renal podocyte development in zebrafish. Expression in liver and skeletal muscle, and up-regulation by starvation suggest a role of LAT3 in the flux of branched-chain amino acids (BCAAs) from liver and skeletal muscle to the bloodstream. Finally, LAT3 is up-regulated in androgen-dependent cancers, suggesting a role in mTORC1 signaling in this type of tumors. In addition, LAT4 might contribute to the transfer of BCAAs from mother to fetus. Unfortunately, the EEG1 mouse model (EEG1(Y221∗)) described here has not yet offered a clue to the physiological role of this orphan protein.
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Affiliation(s)
- Susanna Bodoy
- Institute for Research in Biomedicine (IRB Barcelona), Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Barcelona, and Centro de Investigación Biomedica en Red de Enfermedades Raras, E-08028 Barcelona, Spain
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Abstract
The complexity of food organism interactions necessitates the use of model organisms to understand physiological and pathological processes. In nutrition research, model organisms were initially used to understand how macro and micronutrients are handled in the organism. Currently, in nutritional systems biology, models of increasing complexity are needed in order to determine the global organisation of a biological system and the interaction with food and food components. Originally driven by genetics, certain model organisms have become most prominent. Model organisms are more accessible systems than human beings and include bacteria, yeast, flies, worms, and mammals such as mice. Here, the origin and the reasons to become the most prominent models are presented. Moreover, their applicability in molecular nutrition research is illustrated with selected examples.
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Affiliation(s)
- Isabel Rubio-Aliaga
- Molecular Nutrition Unit, Department of Food and Nutrition, Technische Universität München, Freising, Germany.
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Abstract
Two new potential pharmacologic therapies for recurrent stone disease are described. The role of hyperuricosuria in promoting calcium stones is controversial with only some but not all epidemiologic studies demonstrating associations between increasing urinary uric acid excretion and calcium stone disease. The relationship is supported by the ability of uric acid to "salt out" (or reduce the solubility of) calcium oxalate in vitro. A randomized, controlled trial of allopurinol in patients with hyperuricosuria and normocalciuria was also effective in preventing recurrent stones. Febuxostat, a nonpurine inhibitor of xanthine oxidase (also known as xanthine dehydrogenase or xanthine oxidoreductase) may have advantages over allopurinol and is being tested in a similar protocol, with the eventual goal of determining whether urate-lowering therapy prevents recurrent calcium stones. Treatments for cystinuria have advanced little in the past 30 years. Atomic force microscopy has been used recently to demonstrate that effective inhibition of cystine crystal growth is accomplished at low concentrations of l-cystine methyl ester and l-cystine dimethyl ester, structural analogs of cystine that provide steric inhibition of crystal growth. In vitro, l-cystine dimethyl ester had a significant inhibitory effect on crystal growth. The drug's safety and effectiveness will be tested in an Slc3a1 knockout mouse that serves as an animal model of cystinuria.
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Affiliation(s)
- David S Goldfarb
- Nephrology Section/111G, NY DVAMC, 423 E. 23 Street, New York, NY 10010, USA.
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Abstract
Amino acids are essential building blocks of all mammalian cells. In addition to their role in protein synthesis, amino acids play an important role as energy fuels, precursors for a variety of metabolites and as signalling molecules. Disorders associated with the malfunction of amino acid transporters reflect the variety of roles that they fulfil in human physiology. Mutations of brain amino acid transporters affect neuronal excitability. Mutations of renal and intestinal amino acid transporters affect whole-body homoeostasis, resulting in malabsorption and renal problems. Amino acid transporters that are integral parts of metabolic pathways reduce the function of these pathways. Finally, amino acid uptake is essential for cell growth, thereby explaining their role in tumour progression. The present review summarizes the involvement of amino acid transporters in these roles as illustrated by diseases resulting from transporter malfunction.
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Chillarón J, Font-llitjós M, Fort J, Zorzano A, Goldfarb DS, Nunes V, Palacín M. Pathophysiology and treatment of cystinuria. Nat Rev Nephrol 2010; 6:424-34. [DOI: 10.1038/nrneph.2010.69] [Citation(s) in RCA: 147] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Abstract
Exploiting the potential of omics for clinical diagnosis, prognosis, and therapeutic purposes has currently been receiving a lot of attention. In recent years, most of the effort has been put into demonstrating the possible clinical applications of the various omics fields. The cost-effectiveness analysis has been, so far, rather neglected. The cost of omics-derived applications is still very high, but future technological improvements are likely to overcome this problem. In this chapter, we will give a general background of the main omics fields and try to provide some examples of the most successful applications of omics that might be used in clinical diagnosis and in a therapeutic context.
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Affiliation(s)
- Ewa Gubb
- Bioinformatics, Parque Technológico de Bizkaia, Derio, Spain
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Gabriško M, Janeček Š. Looking for the ancestry of the heavy-chain subunits of heteromeric amino acid transporters rBAT and 4F2hc within the GH13 α-amylase family. FEBS J 2009; 276:7265-78. [DOI: 10.1111/j.1742-4658.2009.07434.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Ercolani M, Sahota A, Schuler C, Yang M, Evan AP, Reimer D, Barone JG, Tischfield JA, Levin RM. Bladder outlet obstruction in male cystinuria mice. Int Urol Nephrol 2009; 42:57-63. [PMID: 19484501 DOI: 10.1007/s11255-009-9597-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2009] [Accepted: 05/19/2009] [Indexed: 11/28/2022]
Abstract
BACKGROUND Cystinuria is the most common inherited cause of urinary tract stones in children. It can lead to obstructive uropathy, which is a major cause of renal failure. Genetic studies have identified two genes, SLC3A1 and SLC7A9, to be directly involved in cystine stone formation. Slc3a1 knockout male mice develop cystine stones in the bladder and, to a lesser extent, in the kidney. Slc3a1 knockout female mice also develop cystinuria, but they do not form stones. The specific aim of this study was to characterize bladder function in cystinuria mice. METHODS Eight control (4 male, 4 female) and 16 Slc3a1 knockout (9 male, 7 female) mice of mixed strain background (C57B/129, age 4-5 months) were evaluated. Each mouse was anesthetized and the bladder dome catheterized for cystometry. Immediately following cystometry, the bladder was excised, weighed, and separated into three full thickness strips for contractile studies. RESULTS Bladders from cystinuria male mice had significantly increased weight, all of them had stones, decreased compliance, and decreased contractile responses to field stimulation, ATP, carbachol, and KCl. Compared with controls, female knockout mice showed normal bladder weight, decreased voiding pressure, slightly decreased compliance, and slightly decreased contractile responses. CONCLUSIONS These studies clearly demonstrate that the bladder stones that developed in the male cystinuria mice resulted in a partial outlet obstruction. Although the female cystinuria mice did not have bladder stones, bladder function was mildly impaired; presumably by the presence of cystine crystals.
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Affiliation(s)
- Mathew Ercolani
- Department of Surgery, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, New Brunswick, NJ, USA
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D'Adamo P, Ulivi S, Beneduci A, Pontoni G, Capasso G, Lanzara C, Andrighetto G, Hladnik U, Nunes V, Palacin M, Gasparini P. Metabonomics and population studies: age-related amino acids excretion and inferring networks through the study of urine samples in two Italian isolated populations. Amino Acids 2010; 38:65-73. [PMID: 19067108 DOI: 10.1007/s00726-008-0205-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2008] [Accepted: 10/22/2008] [Indexed: 11/27/2022]
Abstract
The study of two different Italian isolated populations was combined with a metabonomic approach to better understand tubular handling of amino acids. Levels of amino acids and metabolites have been analyzed by Nucleic Magnetic Resonance and expressed as ratio vs urinary creatinine concentration (mmol/mol). For most of the amino acids there is an age-related U shape pattern of excretion, with the peaks during childhood and old age, and a significant reduction in the adult age. Hierarchical cluster analysis has clearly identified three groups clustering the same amino acids: His, Thr and Ala (group one); Gly and Phe (group two) and a third larger one. Results have been further confirmed by factor and regression analysis, and used to confirm and, in some cases, infer new amino acids networks. As a matter of facts, the identification of strong evidences for clustering of urine excretion of several neutral amino acids suggests the predominant impact of relevant and common transporters.
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Abstract
Cystinuria is an inherited disorder characterized by the impaired reabsorption of cystine in the proximal tubule of the nephron and the gastrointestinal epithelium. The only clinically significant manifestation is recurrent nephrolithiasis secondary to the poor solubility of cystine in urine. Although cystinuria is a relatively common disorder, it accounts for no more than 1% of all urinary tract stones. Thus far, mutations in 2 genes, SLC3A1 and SLC7A9, have been identified as being responsible for most cases of cystinuria by encoding defective subunits of the cystine transporter. With the discovery of mutated genes, the classification of patients with cystinuria has been changed from one based on phenotypes (I, II, III) to one based on the affected genes (I and non-type I; or A and B). Most often this classification can be used without gene sequencing by determining whether the affected individual's parents have abnormal urinary cystine excretion. Clinically, insoluble cystine precipitates into hexagonal crystals that can coalesce into larger, recurrent calculi. Prevention of stone formation is the primary goal of management and includes hydration, dietary restriction of salt and animal protein, urinary alkalinization, and cystine-binding thiol drugs.
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Affiliation(s)
- Aditya Mattoo
- Department of Medicine, NYU School of Medicine, New York, NY, USA
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Affiliation(s)
- Marnie R. Robinson
- Comprehensive Kidney Stone Center, Division of Urologic Surgery, Duke University Medical Center, Durham, North Carolina, and Urology Department, National Naval Medical Center (RLS), Bethesda, Maryland
| | - Regina D. Norris
- Comprehensive Kidney Stone Center, Division of Urologic Surgery, Duke University Medical Center, Durham, North Carolina, and Urology Department, National Naval Medical Center (RLS), Bethesda, Maryland
| | - Roger L. Sur
- Comprehensive Kidney Stone Center, Division of Urologic Surgery, Duke University Medical Center, Durham, North Carolina, and Urology Department, National Naval Medical Center (RLS), Bethesda, Maryland
| | - Glenn M. Preminger
- Comprehensive Kidney Stone Center, Division of Urologic Surgery, Duke University Medical Center, Durham, North Carolina, and Urology Department, National Naval Medical Center (RLS), Bethesda, Maryland
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Barbaric I, Wells S, Russ A, Dear TN. Spectrum of ENU-induced mutations in phenotype-driven and gene-driven screens in the mouse. Environ Mol Mutagen 2007; 48:124-42. [PMID: 17295309 DOI: 10.1002/em.20286] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
N-ethyl-N-nitrosourea (ENU) mutagenesis in mice has become a standard tool for (i) increasing the pool of mutants in many areas of biology, (ii) identifying novel genes involved in physiological processes and disease, and (iii) in assisting in assigning functions to genes. ENU is assumed to cause random mutations throughout the mouse genome, but this presumption has never been analyzed. This is a crucial point, especially for large-scale mutagenesis, as a bias would reflect a constraint on identifying possible genetic targets. There is a significant body of published data now available from both phenotype-driven and gene-driven ENU mutagenesis screens in the mouse that can be used to reveal the effectiveness and limitations of an ENU mutagenesis approach. Analysis of the published data is presented in this paper. As expected for a randomly acting mutagen, ENU-induced mutations identified in phenotype-driven screens were in genes that had higher coding sequence length and higher exon number than the average for the mouse genome. Unexpectedly, the data showed that ENU-induced mutations were more likely to be found in genes that had a higher G + C content and neighboring base analysis revealed that the identified ENU mutations were more often directly flanked by G or C nucleotides. ENU mutations from phenotype-driven and gene-driven screens were dominantly A:T to T:A transversions or A:T to G:C transitions. Knowledge of the spectrum of mutations that ENU elicits will assist in positional cloning of ENU-induced mutations by allowing prioritization of candidate genes based on some of their inherent features.
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Affiliation(s)
- Ivana Barbaric
- Department of Biomedical Science, University of Sheffield, Sheffield, United Kingdom
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Francés F, Portolés O, Corella D, Sorlí JV, Sabater A, Carrasco P, Guillén M. [SLC7A9 gene variation: impact of 13 frequent mutations in the etiology of cystinuria in a Spanish Mediterranean population]. Med Clin (Barc) 2006; 127:161-6. [PMID: 16834950 DOI: 10.1157/13090704] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
BACKGROUND AND OBJECTIVE The aim of this study was to investigate the presence of the most prevalent mutation in the SLC7A9 gene in families of the Mediterranean Spanish population and their association with clinical phenotypes. PATIENTS AND METHOD Twenty cystinuria families were studied (6 type I, 12 non type I, and 2 unknown type), including 48 cystinuria patients and 44 relatives. DNA was isolated and molecular analysis of 13 variations (P52L, N58_G79del22, G63R, G105R, T123M, V170M, A182T, V188M, c.614dupA, G259R, L283F, A316V and R333W) in the SLC7A9 gene was undertaken. Association studies between these mutations and urinary aminoacid concentrations, stones, urinary infections, colics and other clinical traits were carried out. RESULTS Of the 13 investigated mutations, the most prevalent mutation in cystinuria patients was c.614dupA (17.1%), which was found in 13 patients in heterozygous state (17.1%) and in 2 relatives, all of them belonging to 4 non type I families. Mutations G105R (9.2%), T123M (3.9%) and N58_G79del22 (2.6%) were detected only in non type I cystinuria patients. Meanwhile, a R333W carrier allele was found in a patient of a unknown family, and a G105R allele in a relative of a non type I family. No mutation was found in type I families and no patients with mutations in both SLC3A1 and SLC7A9 genes were found in any family. CONCLUSIONS Although we have not carried out the whole screening of SLC7A9 gene, the detection rate of variations in SLC7A9 gene suggests a greater impact of this gene in the etiology of cystinuria in our population than variations in the previously screened SLC3A1 gene. The wide variation of phenotypical traits in subjects of families with the same mutations suggests that further investigation of other genetic and/or environmental factors should be carried out.
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Affiliation(s)
- Francesc Francés
- Unidad de Epidemiología Genética y Molecular, Departamento de Medicina Preventiva, Facultad de Medicina, Universitat de València, Valencia, España
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Liang L, Chen J, Vittal R, Selvanayagam ZE, McAteer JA, Deng L, Tischfield J, Chin KV, Sahota A. Expression Profiling of Crystal-Induced Injury in Human Kidney Epithelial Cells. ACTA ACUST UNITED AC 2006; 103:p53-62. [PMID: 16374038 DOI: 10.1159/000090503] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2004] [Accepted: 09/25/2005] [Indexed: 11/19/2022]
Abstract
BACKGROUND Deposition of crystals within tubular lumens is a feature of many kidney stone diseases, including crystals of calcium oxalate monohydrate (COM) in primary hyperoxaluria and of 2,8-dihydroxyadenine (DHA) in adenine phosphoribosyltransferase deficiency. Crystals are injurious to renal epithelial cells, but the molecular bases of cell injury have not been well characterized. METHODS We used a cDNA microarray to identify the time-dependent changes in gene expression associated with the interaction of COM or DHA crystals with primary cultures of normal human kidney cortical epithelial cells. RESULTS We observed gene expression changes that were common to both crystal types, as well as a number of crystal-specific responses. A subset of genes known to be aberrantly expressed in kidney tissue from stone formers also showed an altered expression in COM- or DHA-treated normal human kidney cortical epithelial cells. CONCLUSIONS Our results show that cultured epithelial cells exposed to COM or DHA crystals demonstrate cellular responses that may be physiologically relevant, thus suggesting that this experimental system may be useful for elucidating the mechanisms of crystal-induced renal cell injury.
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Affiliation(s)
- Li Liang
- Department of Genetics, Rutgers University, Piscataway, NJ 08854, USA
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Font-Llitjós M, Jiménez-Vidal M, Bisceglia L, Di Perna M, de Sanctis L, Rousaud F, Zelante L, Palacín M, Nunes V. New insights into cystinuria: 40 new mutations, genotype-phenotype correlation, and digenic inheritance causing partial phenotype. J Med Genet 2006; 42:58-68. [PMID: 15635077 PMCID: PMC1735913 DOI: 10.1136/jmg.2004.022244] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
OBJECTIVE To clarify the genotype-phenotype correlation and elucidate the role of digenic inheritance in cystinuria. METHODS 164 probands from the International Cystinuria Consortium were screened for mutations in SLC3A1 (type A) and SLC7A9 (type B) and classified on the basis of urine excretion of cystine and dibasic amino acids by obligate heterozygotes into 37 type I (silent heterozygotes), 46 type non-I (hyperexcretor heterozygotes), 14 mixed, and 67 untyped probands. RESULTS Mutations were identified in 97% of the probands, representing 282 alleles (86.8%). Forty new mutations were identified: 24 in SLC3A1 and 16 in SLC7A9. Type A heterozygotes showed phenotype I, but mutation DupE5-E9 showed phenotype non-I in some heterozygotes. Type B heterozygotes showed phenotype non-I, with the exception of 10 type B mutations which showed phenotype I in some heterozygotes. Thus most type I probands carried type A mutations and all type non-I probands carried type B mutations. Types B and A mutations contributed to mixed type, BB being the most representative genotype. Two mixed cystinuria families transmitted mutations in both genes: double compound heterozygotes (type AB) had greater aminoaciduria than single heterozygotes in their family. CONCLUSIONS Digenic inheritance is an exception (two of 164 families), with a limited contribution to the aminoaciduria values (partial phenotype) in cystinuria. Further mutational analysis could focus on one of the two genes (SLC3A1 preferentially for type I and SLC7A9 for type non-I probands), while for mixed probands analysis of both genes might be required, with priority given to SLC7A9.
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Affiliation(s)
- M Font-Llitjós
- Centre of Medical and Molecular Genetics (IRO), Hospital Duran i Reynals, Barcelona, Spain
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Vernon HJ, Osborne C, Tzortzaki EG, Yang M, Chen J, Rittling SR, Denhardt DT, Buyske S, Bledsoe SB, Evan AP, Fairbanks L, Simmonds HA, Tischfield JA, Sahota A. Aprt/Opn double knockout mice: osteopontin is a modifier of kidney stone disease severity. Kidney Int 2006; 68:938-47. [PMID: 16105024 DOI: 10.1111/j.1523-1755.2005.00487.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
BACKGROUND Osteopontin (OPN) is reported to have two distinct functions in kidney disease: Promotion of inflammation at sites of tissue injury, and inhibition of calcium oxalate monohydrate stone formation. However, many of the studies supporting these functions were carried out in animal models of acute renal injury or in cultured cells; thus, the role of OPN in chronic renal disease is not well defined. We examined the role of OPN in adenine phosphoribosyltransferase (Aprt) knockout mice, in which inflammation and formation of 2,8-dihydroxyadenine (DHA) kidney stones are prominent features, by generating Aprt/Opn double knockout mice. METHODS We characterized the phenotypes of six- and 12-week-old Aprt-/- Opn-/-, Aprt-/- Opn+/+, Aprt+/+ Opn-/-, and Aprt+/+ Opn+/+ male and female mice using biochemical, histologic, immunohistochemical, and in situ hybridization techniques. RESULTS At 6 weeks of age, there was no difference in phenotype between double knockout and Aprt knockout mice. At 12 weeks, there was increased adenine and DHA excretion, renal crystal deposition, and inflammation in double knockout versus Aprt knockout male mice. Double knockout and Aprt knockout female mice at 12 weeks had less pathology than their male counterparts, but kidneys from double knockout females showed more inflammation compared with Aprt knockout females; both genotypes had similar levels of DHA crystal deposition. CONCLUSION We conclude that (1) OPN is a major inhibitor of DHA crystal deposition and inflammation in male mice; and (2) OPN is a major modifier of the inflammatory response but not of crystal deposition in female mice. Thus, separate mechanisms appear responsible for the tissue changes seen in DKO males versus females.
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Affiliation(s)
- Hilary J Vernon
- Department of Genetics, Rutgers University, Piscataway, New Jersey 08854-8082, USA
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Yuen YP, Lam CW, Lai CK, Tong SF, Li PS, Tam S, Kwan EYW, Chan SY, Tsang WK, Chan KY, Mak WL, Cheng CW, Chan YW. Heterogeneous mutations in the SLC3A1 and SLC7A9 genes in Chinese patients with cystinuria. Kidney Int 2006; 69:123-8. [PMID: 16374432 DOI: 10.1038/sj.ki.5000003] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Cystinuria is a recessively inherited aminoaciduria that leads to recurrent urolithiasis. It is caused by the defective transport of cystine and dibasic amino acids in the proximal renal tubules and intestinal epithelium. Two genes responsible for this, SLC3A1 and SLC7A9, are known. Patients with two SLC3A1 mutations are classified as type A cystinuria, whereas patients with two SLC7A9 mutations are classified as type B cystinuria. Few clinical and molecular data have been reported for Asian cystinuria patients. In this study, we determined the molecular basis of cystinuria in eight unrelated Chinese subjects. Coding exons and flanking introns of the SLC3A1 and SLC7A9 genes were directly sequenced after amplification by polymerase chain reaction. Five different SLC3A1 mutations were found. Two missense mutations, D210G and S547L, were novel. The other three SLC3A1 mutations (IVS6+2T>C, R181Q and R365W) have been described previously. In addition, four novel SLC7A9 mutations, C137R, c.730delG, IVS10+2_3delTG and IVS12+3insT, together with two previously reported mutations (A70V and G195R) were found. All patients except one carried compound heterozygous mutations. IVS12+3insT was detected in patients from two families. This is the first molecular genetic study on Chinese cystinuria patients. Three patients with type A cystinuria, two with type B cystinuria, and three carriers of type B cystinuria were identified. Our results suggest that the molecular basis of cystinuria is heterogeneous in our local population.
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Affiliation(s)
- Y-P Yuen
- Department of Pathology, Princess Margaret Hospital, Hong Kong, China
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Palacín M, Nunes V, Font-Llitjós M, Jiménez-Vidal M, Fort J, Gasol E, Pineda M, Feliubadaló L, Chillarón J, Zorzano A. The Genetics of Heteromeric Amino Acid Transporters. Physiology (Bethesda) 2005; 20:112-24. [PMID: 15772300 DOI: 10.1152/physiol.00051.2004] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Heteromeric amino acid transporters (HATs) are composed of a heavy ( SLC3 family) and a light ( SLC7 family) subunit. Mutations in system b0,+(rBAT-b0,+AT) and in system y+L (4F2hc-y+LAT1) cause the primary inherited aminoacidurias (PIAs) cystinuria and lysinuric protein intolerance, respectively. Recent developments [including the identification of the first Hartnup disorder gene (B0AT1; SLC6A19)] and knockout mouse models have begun to reveal the basis of renal and intestinal reabsorption of amino acids in mammals.
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Affiliation(s)
- Manuel Palacín
- Department of Biochemistry and Molecular Biology, Faculty of Biology and Institut de Recerca Biomedica de Barcelona, Barcelona Science Park, University of Barcelona, Spain.
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Verri T, Dimitri C, Treglia S, Storelli F, De Micheli S, Ulianich L, Vito P, Marsigliante S, Storelli C, Di Jeso B. Multiple pathways for cationic amino acid transport in rat thyroid epithelial cell line PC Cl3. Am J Physiol Cell Physiol 2005; 288:C290-303. [PMID: 15483229 DOI: 10.1152/ajpcell.00053.2004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Information regarding cationic amino acid transport systems in thyroid is limited to Northern blot detection of y+LAT1 mRNA in the mouse. This study investigated cationic amino acid transport in PC cell line clone 3 (PC Cl3 cells), a thyroid follicular cell line derived from a normal Fisher rat retaining many features of normal differentiated follicular thyroid cells. We provide evidence that in PC Cl3 cells plasmalemmal transport of cationic amino acids is Na+independent and occurs, besides diffusion, with the contribution of high-affinity, carrier-mediated processes. Carrier-mediated transport is via y+, y+L, and b0,+systems, as assessed by l-arginine uptake and kinetics, inhibition of l-arginine transport by N-ethylmaleimide and neutral amino acids, and l-cystine transport studies. y+L and y+systems account for the highest transport rate (with y+L > y+) and b0,+for a residual fraction of the transport. Uptake data correlate to expression of the genes encoding for CAT-1, CAT-2B, 4F2hc, y+LAT1, y+LAT2, rBAT, and b0,+AT, an expression profile that is also shown by the rat thyroid gland. In PC Cl3 cells cationic amino acid uptake is under TSH and/or cAMP control (with transport increasing with increasing TSH concentration), and upregulation of CAT-1, CAT-2B, 4F2hc/y+LAT1, and rBAT/b0,+AT occurs at the mRNA level under TSH stimulation. Our results provide the first description of an expression pattern of cationic amino acid transport systems in thyroid cells. Furthermore, we provide evidence that extracellular l-arginine is a crucial requirement for normal PC Cl3 cell growth and that long-term l-arginine deprivation negatively influences CAT-2B expression, as it correlates to reduction of CAT-2B mRNA levels.
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Affiliation(s)
- Tiziano Verri
- Laboratory of General Physiology, Department of Biological and Environmental Sciences and Technologies, University of Lecce, Lecce, Italy.
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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] [What about the content of this article? (0)] [Affiliation(s)] [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.
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Affiliation(s)
- Marta Pineda
- Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Barcelona, Spain
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