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Sumayao R, Newsholme P, McMorrow T. The Role of Cystinosin in the Intermediary Thiol Metabolism and Redox Homeostasis in Kidney Proximal Tubular Cells. Antioxidants (Basel) 2018; 7:antiox7120179. [PMID: 30513914 PMCID: PMC6315507 DOI: 10.3390/antiox7120179] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Revised: 11/22/2018] [Accepted: 11/24/2018] [Indexed: 01/26/2023] Open
Abstract
Cystinosin is a lysosomal transmembrane protein which facilitates transport of the disulphide amino acid cystine (CySS) from the lysosomes of the cell. This protein is encoded by the CTNS gene which is defective in the lysosomal storage disorder, cystinosis. Because of the apparent involvement of cystinosin in the intermediary thiol metabolism, its discovery has fuelled investigations into its role in modulating cellular redox homeostasis. The kidney proximal tubular cells (PTCs) have become the focus of various studies on cystinosin since the protein is highly expressed in these cells and kidney proximal tubular transport dysfunction is the foremost clinical manifestation of cystinosis. The lysosomal CySS pool is a major source of cytosolic cysteine (Cys), the limiting amino acid for the synthesis of an important antioxidant glutathione (GSH) via the γ-glutamyl cycle. Therefore, loss of cystinosin function is presumed to lead to cytosolic deficit of Cys which may impair GSH synthesis. However, studies using in vitro models lacking cystinosin yielded inconsistent results and failed to establish the mechanistic role of cystinosin in modulating GSH synthesis and redox homeostasis. Because of the complexity of the metabolic micro- and macro-environment in vivo, using in vitro models alone may not be able to capture the complete sequence of biochemical and physiological events that occur as a consequence of loss of cystinosin function. The coexistence of pathways for the overall handling and disposition of GSH, the modulation of CTNS gene by intracellular redox status and the existence of a non-canonical isoform of cystinosin may constitute possible rescue mechanisms in vivo to remediate redox perturbations in renal PTCs. Importantly, the mitochondria seem to play a critical role in orchestrating redox imbalances initiated by cystinosin dysfunction. Non-invasive techniques such as in vivo magnetic resonance imaging with the aid of systems biology approaches may provide invaluable mechanistic insights into the role of cystinosin in the essential intermediary thiol metabolism and in the overall regulation cellular redox homeostasis.
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Affiliation(s)
- Rodolfo Sumayao
- Chemistry Department, De La Salle University, Manila 1004, Philippines.
| | - Philip Newsholme
- School of Pharmacy and Biomedical Sciences and Curtin Health Innovation Research Institute (CHIRI), Curtin University, Perth 6845, Australia.
| | - Tara McMorrow
- Conway Institute, School of Biomolecular and Biomedical Science, University College Dublin, Dublin 4, Ireland.
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2
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Elmonem MA, Veys K, Oliveira Arcolino F, Van Dyck M, Benedetti MC, Diomedi-Camassei F, De Hertogh G, van den Heuvel LP, Renard M, Levtchenko E. Allogeneic HSCT transfers wild-type cystinosin to nonhematological epithelial cells in cystinosis: First human report. Am J Transplant 2018; 18:2823-2828. [PMID: 30030899 DOI: 10.1111/ajt.15029] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 06/28/2018] [Accepted: 07/12/2018] [Indexed: 01/25/2023]
Abstract
Cystinosis is an autosomal recessive lysosomal storage disorder characterized by the defective transport of the amino acid cystine out of the lysosome due to a deficiency of cystinosin, the lysosomal cystine transporter. Patients have lysosomal cystine accumulation in various tissues, leading to cellular stress and damage, particularly in the kidney, cornea, and other extrarenal tissues. Cysteamine, a cystine-depleting agent, improves survival and delays the progression of disease, but it does not prevent the development of either renal failure or extrarenal complications. Furthermore, the drug has severe adverse effects that significantly reduce patient compliance. Allogeneic hematopoietic stem cell transplantation (HSCT) is currently established as a therapeutic option for many inborn errors of metabolism, where the main pathologic driving factor is an enzyme deficiency. Recent studies in the cystinosis mouse-model suggested that HSCT could be a curative treatment alternative to cysteamine therapy. We treated a 16-year-old boy who had infantile cystinosis and side effects of cysteamine therapy with HSCT. We were able to demonstrate successful transfer of the wild-type cystinosin protein and CTNS mRNA to nonhematological epithelial cells in the recipient, as well as a decrease in the tissue cystine-crystal burden. This is the first report of allogeneic HSCT in a patient with cystinosis, the prototype of lysosomal membrane-transporter disorders.
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Affiliation(s)
- Mohamed A Elmonem
- Department of Pediatric Nephrology & Development and Regeneration, University Hospitals Leuven, KU Leuven - University of Leuven, Leuven, Belgium.,Department of Clinical and Chemical Pathology, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Koenraad Veys
- Department of Pediatric Nephrology & Development and Regeneration, University Hospitals Leuven, KU Leuven - University of Leuven, Leuven, Belgium
| | - Fanny Oliveira Arcolino
- Department of Pediatric Nephrology & Development and Regeneration, University Hospitals Leuven, KU Leuven - University of Leuven, Leuven, Belgium
| | - Maria Van Dyck
- Department of Pediatric Nephrology & Development and Regeneration, University Hospitals Leuven, KU Leuven - University of Leuven, Leuven, Belgium
| | - Maria C Benedetti
- Department of Laboratories, Pathology Unit, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | | | - Gert De Hertogh
- Department of Translational Cell and Tissue Research, KU Leuven - University of Leuven, Leuven, Belgium
| | - Lambertus P van den Heuvel
- Department of Pediatric Nephrology & Development and Regeneration, University Hospitals Leuven, KU Leuven - University of Leuven, Leuven, Belgium.,Department of Pediatric Nephrology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Marleen Renard
- Department of Pediatric Hematology and Oncology, KU Leuven - University of Leuven, Leuven, Belgium
| | - Elena Levtchenko
- Department of Pediatric Nephrology & Development and Regeneration, University Hospitals Leuven, KU Leuven - University of Leuven, Leuven, Belgium
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3
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Kandasamy P, Gyimesi G, Kanai Y, Hediger MA. Amino acid transporters revisited: New views in health and disease. Trends Biochem Sci 2018; 43:752-789. [PMID: 30177408 DOI: 10.1016/j.tibs.2018.05.003] [Citation(s) in RCA: 263] [Impact Index Per Article: 43.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2018] [Revised: 05/23/2018] [Accepted: 05/25/2018] [Indexed: 02/09/2023]
Abstract
Amino acid transporters (AATs) are membrane-bound transport proteins that mediate transfer of amino acids into and out of cells or cellular organelles. AATs have diverse functional roles ranging from neurotransmission to acid-base balance, intracellular energy metabolism, and anabolic and catabolic reactions. In cancer cells and diabetes, dysregulation of AATs leads to metabolic reprogramming, which changes intracellular amino acid levels, contributing to the pathogenesis of cancer, obesity and diabetes. Indeed, the neutral amino acid transporters (NATs) SLC7A5/LAT1 and SLC1A5/ASCT2 are likely involved in several human malignancies. However, a clinical therapy that directly targets AATs has not yet been developed. The purpose of this review is to highlight the structural and functional diversity of AATs, their diverse physiological roles in different tissues and organs, their wide-ranging implications in human diseases and the emerging strategies and tools that will be necessary to target AATs therapeutically.
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Affiliation(s)
- Palanivel Kandasamy
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bühlstrasse 28, CH-3012 Bern, Switzerland
| | - Gergely Gyimesi
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bühlstrasse 28, CH-3012 Bern, Switzerland
| | - Yoshikatsu Kanai
- Division of Bio-system Pharmacology, Graduate School of Medicine, Osaka University, Osaka, Japan.
| | - Matthias A Hediger
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bühlstrasse 28, CH-3012 Bern, Switzerland.
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4
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Zhang J, Johnson JL, He J, Napolitano G, Ramadass M, Rocca C, Kiosses WB, Bucci C, Xin Q, Gavathiotis E, Cuervo AM, Cherqui S, Catz SD. Cystinosin, the small GTPase Rab11, and the Rab7 effector RILP regulate intracellular trafficking of the chaperone-mediated autophagy receptor LAMP2A. J Biol Chem 2017; 292:10328-10346. [PMID: 28465352 DOI: 10.1074/jbc.m116.764076] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Revised: 04/28/2017] [Indexed: 12/12/2022] Open
Abstract
The lysosomal storage disease cystinosis, caused by cystinosin deficiency, is characterized by cell malfunction, tissue failure, and progressive renal injury despite cystine-depletion therapies. Cystinosis is associated with defects in chaperone-mediated autophagy (CMA), but the molecular mechanisms are incompletely understood. Here, we show CMA substrate accumulation in cystinotic kidney proximal tubule cells. We also found mislocalization of the CMA lysosomal receptor LAMP2A and impaired substrate translocation into the lysosome caused by defective CMA in cystinosis. The impaired LAMP2A trafficking and localization were rescued either by the expression of wild-type cystinosin or by the disease-associated point mutant CTNS-K280R, which has no cystine transporter activity. Defective LAMP2A trafficking in cystinosis was found to associate with decreased expression of the small GTPase Rab11 and the Rab7 effector RILP. Defective Rab11 trafficking in cystinosis was rescued by treatment with small-molecule CMA activators. RILP expression was restored by up-regulation of the transcription factor EB (TFEB), which was down-regulated in cystinosis. Although LAMP2A expression is independent of TFEB, TFEB up-regulation corrected lysosome distribution and lysosomal LAMP2A localization in Ctns-/- cells but not Rab11 defects. The up-regulation of Rab11, Rab7, or RILP, but not its truncated form RILP-C33, rescued LAMP2A-defective trafficking in cystinosis, whereas dominant-negative Rab11 or Rab7 impaired LAMP2A trafficking. Treatment of cystinotic cells with a CMA activator increased LAMP2A localization at the lysosome and increased cell survival. Altogether, we show that LAMP2A trafficking is regulated by cystinosin, Rab11, and RILP and that CMA up-regulation is a potential clinically relevant mechanism to increase cell survival in cystinosis.
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Affiliation(s)
- Jinzhong Zhang
- From the Department of Molecular Medicine, The Scripps Research Institute, La Jolla, California 92037
| | - Jennifer L Johnson
- From the Department of Molecular Medicine, The Scripps Research Institute, La Jolla, California 92037
| | - Jing He
- From the Department of Molecular Medicine, The Scripps Research Institute, La Jolla, California 92037
| | - Gennaro Napolitano
- From the Department of Molecular Medicine, The Scripps Research Institute, La Jolla, California 92037
| | - Mahalakshmi Ramadass
- From the Department of Molecular Medicine, The Scripps Research Institute, La Jolla, California 92037
| | - Celine Rocca
- the Department of Pediatrics, Division of Genetics, University of California, San Diego, La Jolla, California 92093-0734
| | - William B Kiosses
- From the Department of Molecular Medicine, The Scripps Research Institute, La Jolla, California 92037
| | - Cecilia Bucci
- the Department of Biological and Environmental Sciences and Technologies (DiSTeBA), University of Salento, Via Provinciale Monteroni n. 165, 73100 Lecce, Italy, and
| | - Qisheng Xin
- the Departments of Biochemistry and.,Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, New York 10461
| | | | - Ana María Cuervo
- Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Stephanie Cherqui
- the Department of Pediatrics, Division of Genetics, University of California, San Diego, La Jolla, California 92093-0734
| | - Sergio D Catz
- From the Department of Molecular Medicine, The Scripps Research Institute, La Jolla, California 92037,
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5
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Elmonem MA, Khalil R, Khodaparast L, Khodaparast L, Arcolino FO, Morgan J, Pastore A, Tylzanowski P, Ny A, Lowe M, de Witte PA, Baelde HJ, van den Heuvel LP, Levtchenko E. Cystinosis (ctns) zebrafish mutant shows pronephric glomerular and tubular dysfunction. Sci Rep 2017; 7:42583. [PMID: 28198397 PMCID: PMC5309805 DOI: 10.1038/srep42583] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Accepted: 01/12/2017] [Indexed: 01/05/2023] Open
Abstract
The human ubiquitous protein cystinosin is responsible for transporting the disulphide amino acid cystine from the lysosomal compartment into the cytosol. In humans, Pathogenic mutations of CTNS lead to defective cystinosin function, intralysosomal cystine accumulation and the development of cystinosis. Kidneys are initially affected with generalized proximal tubular dysfunction (renal Fanconi syndrome), then the disease rapidly affects glomeruli and progresses towards end stage renal failure and multiple organ dysfunction. Animal models of cystinosis are limited, with only a Ctns knockout mouse reported, showing cystine accumulation and late signs of tubular dysfunction but lacking the glomerular phenotype. We established and characterized a mutant zebrafish model with a homozygous nonsense mutation (c.706 C > T; p.Q236X) in exon 8 of ctns. Cystinotic mutant larvae showed cystine accumulation, delayed development, and signs of pronephric glomerular and tubular dysfunction mimicking the early phenotype of human cystinotic patients. Furthermore, cystinotic larvae showed a significantly increased rate of apoptosis that could be ameliorated with cysteamine, the human cystine depleting therapy. Our data demonstrate that, ctns gene is essential for zebrafish pronephric podocyte and proximal tubular function and that the ctns-mutant can be used for studying the disease pathogenic mechanisms and for testing novel therapies for cystinosis.
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Affiliation(s)
- Mohamed A Elmonem
- Department of Paediatric Nephrology &Growth and Regeneration, University Hospitals Leuven KU Leuven - University of Leuven, Leuven, Belgium.,Department of Clinical and Chemical Pathology, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Ramzi Khalil
- Department of Pathology, Leiden University Medical Centre, The Netherlands
| | - Ladan Khodaparast
- Department of Cellular and Molecular Medicine, Switch Laboratory, VIB, University Hospitals Leuven KU Leuven - University of Leuven, Leuven, Belgium
| | - Laleh Khodaparast
- Department of Cellular and Molecular Medicine, Switch Laboratory, VIB, University Hospitals Leuven KU Leuven - University of Leuven, Leuven, Belgium
| | - Fanny O Arcolino
- Department of Paediatric Nephrology &Growth and Regeneration, University Hospitals Leuven KU Leuven - University of Leuven, Leuven, Belgium
| | - Joseph Morgan
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Anna Pastore
- Laboratory of Proteomics and Metabolomics, Children's Hospital and Research Institute "Bambino Gesù" IRCCS, Rome, Italy
| | - Przemko Tylzanowski
- Department of Development and Regeneration, Laboratory for Developmental and Stem Cell Biology, Skeletal Biology and Engineering Research Centre, KU Leuven - University of Leuven, Leuven, Belgium.,Department of Biochemistry and Molecular Biology, Medical University, Lublin, Poland
| | - Annelii Ny
- Laboratory for Molecular Bio-discovery, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven - University of Leuven, Leuven, Belgium
| | - Martin Lowe
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Peter A de Witte
- Laboratory for Molecular Bio-discovery, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven - University of Leuven, Leuven, Belgium
| | - Hans J Baelde
- Department of Pathology, Leiden University Medical Centre, The Netherlands
| | - Lambertus P van den Heuvel
- Department of Paediatric Nephrology &Growth and Regeneration, University Hospitals Leuven KU Leuven - University of Leuven, Leuven, Belgium.,Department of Paediatric Nephrology, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Elena Levtchenko
- Department of Paediatric Nephrology &Growth and Regeneration, University Hospitals Leuven KU Leuven - University of Leuven, Leuven, Belgium
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6
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Cystinosin-LKG rescues cystine accumulation and decreases apoptosis rate in cystinotic proximal tubular epithelial cells. Pediatr Res 2017; 81:113-119. [PMID: 27656773 DOI: 10.1038/pr.2016.184] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 08/10/2016] [Indexed: 01/19/2023]
Abstract
BACKGROUND Nephropathic cystinosis is a lysosomal storage disease that is caused by mutations in the CTNS gene encoding a cystine/proton symporter cystinosin and an isoform cystinosin-LKG which is generated by an alternative splicing of exon 12. We have investigated the physiological role of the cystinosin-LKG that is widely expressed in epithelial tissues. METHODS We have analyzed the intracellular localization and the function of the cystinosin-LKG conjugated with DsRed (cystinosin-LKG-RFP) in Madin-Darby canine kidney cells (MDCK II) and in proximal tubular epithelial cells carrying a deletion of the CTNS gene (cystinotic PTEC), respectively. RESULTS Cystinosin-LKG-RFP colocalized with markers of lysosomes, late endosomes and was also expressed on the apical surface of polarized MDCK II cells. Moreover, immune-electron microscopy images of MDCK II cells overexpressing cystinosin-LKG-RFP showed stacked lamellar membranes inside perinuclear lysosomal structures. To study the role of LKG-isoform, we have investigated cystine accumulation and apoptosis that have been described in cystinotic cells. Cystinosin-LKG decreased cystine levels by approximately 10-fold similarly to cystinosin-RFP. The levels of TNFα- and actinomycin D-inducted apoptosis dropped in cystinotic cells expressing LKG-isoform. This effect was also similar to the main isoform. CONCLUSION Our results suggest that cystinosin-LKG and cystinosin move similar functional activities in cells.
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7
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Cherqui S, Courtoy PJ. The renal Fanconi syndrome in cystinosis: pathogenic insights and therapeutic perspectives. Nat Rev Nephrol 2016; 13:115-131. [PMID: 27990015 DOI: 10.1038/nrneph.2016.182] [Citation(s) in RCA: 106] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Cystinosis is an autosomal recessive metabolic disease that belongs to the family of lysosomal storage disorders. It is caused by a defect in the lysosomal cystine transporter, cystinosin, which results in an accumulation of cystine in all organs. Despite the ubiquitous expression of cystinosin, a renal Fanconi syndrome is often the first manifestation of cystinosis, usually presenting within the first year of life and characterized by the early and severe dysfunction of proximal tubule cells, highlighting the unique vulnerability of this cell type. The current therapy for cystinosis, cysteamine, facilitates lysosomal cystine clearance and greatly delays progression to kidney failure but is unable to correct the Fanconi syndrome. This Review summarizes decades of studies that have fostered a better understanding of the pathogenesis of the renal Fanconi syndrome associated with cystinosis. These studies have unraveled some of the early molecular changes that occur before the onset of tubular atrophy and identified a role for cystinosin beyond cystine transport, in endolysosomal trafficking and proteolysis, lysosomal clearance, autophagy and the regulation of energy balance. These studies have also led to the identification of new potential therapeutic targets and here, we outline the potential role of stem cell therapy for cystinosis and provide insights into the mechanism of haematopoietic stem cell-mediated kidney protection.
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Affiliation(s)
- Stephanie Cherqui
- Department of Pediatrics, Division of Genetics, University of California San Diego, 9500 Gilman Drive, MC 0734, La Jolla, California 92093-0734, USA
| | - Pierre J Courtoy
- Cell biology, de Duve Institute and Université catholique de Louvain, UCL-Brussels, 75 Avenue Hippocrate, B-1200 Brussels, Belgium
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8
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Bellomo F, Taranta A, Petrini S, Venditti R, Rocchetti MT, Rega LR, Corallini S, Gesualdo L, De Matteis MA, Emma F. Carboxyl-Terminal SSLKG Motif of the Human Cystinosin-LKG Plays an Important Role in Plasma Membrane Sorting. PLoS One 2016; 11:e0154805. [PMID: 27148969 PMCID: PMC4858208 DOI: 10.1371/journal.pone.0154805] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Accepted: 04/19/2016] [Indexed: 11/18/2022] Open
Abstract
Cystinosin mediates an ATP-dependent cystine efflux from lysosomes and causes, if mutated, nephropathic cystinosis, a rare inherited lysosomal storage disease. Alternative splicing of the last exon of the cystinosin sequence produces the cystinosin-LKG isoform that is characterized by a different C-terminal region causing changes in the subcellular distribution of the protein. We have constructed RFP-tagged proteins and demonstrated by site-directed mutagenesis that the carboxyl-terminal SSLKG sequence of cystinosin-LKG is an important sorting motif that is required for efficient targeting the protein to the plasma membrane, where it can mediate H+ coupled cystine transport. Deletion of the SSLKG sequence reduced cystinosin-LKG expression in the plasma membrane and cystine transport by approximately 30%, and induced significant accumulation of the protein in the Golgi apparatus and in lysosomes. Cystinosin-LKG, unlike the canonical isoform, also moves to the lysosomes by the indirect pathway, after endocytic retrieval from the plasma membrane, mainly by a clathrin-mediated endocytosis. Nevertheless, silencing of AP-2 triggers the clathrin-independent endocytosis, showing the complex adaptability of cystinosin-LKG trafficking.
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Affiliation(s)
- Francesco Bellomo
- Department of Nephrology-Urology, Division of Nephrology and Dialysis, Bambino Gesù Children’s Hospital and Research Institute, Rome, Italy
- * E-mail:
| | - Anna Taranta
- Department of Nephrology-Urology, Division of Nephrology and Dialysis, Bambino Gesù Children’s Hospital and Research Institute, Rome, Italy
| | - Stefania Petrini
- Confocal Microscopy Core Facility, Bambino Gesù Children’s Hospital and Research Institute, Rome, Italy
| | - Rossella Venditti
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli (NA), Italy
| | - Maria Teresa Rocchetti
- Department of Emergency and Organ Transplantation (DETO), Nephrology, Dialysis and Transplantation Unit, University of Bari Aldo Moro, Bari, Italy
| | - Laura Rita Rega
- Department of Nephrology-Urology, Division of Nephrology and Dialysis, Bambino Gesù Children’s Hospital and Research Institute, Rome, Italy
| | - Serena Corallini
- Department of Nephrology-Urology, Division of Nephrology and Dialysis, Bambino Gesù Children’s Hospital and Research Institute, Rome, Italy
| | - Loreto Gesualdo
- Department of Emergency and Organ Transplantation (DETO), Nephrology, Dialysis and Transplantation Unit, University of Bari Aldo Moro, Bari, Italy
| | | | - Francesco Emma
- Department of Nephrology-Urology, Division of Nephrology and Dialysis, Bambino Gesù Children’s Hospital and Research Institute, Rome, Italy
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9
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Ivanova EA, Arcolino FO, Elmonem MA, Rastaldi MP, Giardino L, Cornelissen EM, van den Heuvel LP, Levtchenko EN. Cystinosin deficiency causes podocyte damage and loss associated with increased cell motility. Kidney Int 2016; 89:1037-1048. [PMID: 27083281 DOI: 10.1016/j.kint.2016.01.013] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Revised: 12/22/2015] [Accepted: 01/07/2016] [Indexed: 12/14/2022]
Abstract
The involvement of the glomerulus in the pathogenesis of cystinosis, caused by loss-of-function mutations in cystinosin (CTNS, 17p13), is a matter of controversy. Although patients with cystinosis demonstrate glomerular lesions and high-molecular-weight proteinuria starting from an early age, a mouse model of cystinosis develops only signs of proximal tubular dysfunction. Here we studied podocyte damage in patients with cystinosis by analyzing urinary podocyte excretion and by in vitro studies of podocytes deficient in cystinosin. Urine from patients with cystinosis presented a significantly higher amount of podocytes compared with controls. In culture, cystinotic podocytes accumulated cystine compatible with cystinosin deficiency. The expression of podocyte specific genes CD2AP, podocalyxin, and synaptopodin and of the WT1 protein was evident in all cell lines. Conditionally immortalized podocyte lines of 2 patients with different CTNS mutations had altered cytoskeleton, impaired cell adhesion sites, and increased individual cell motility. Moreover, these cells showed enhanced phosphorylation of both Akt1 and Akt2 (isoforms of protein kinase B). Inhibition of Akt by a specific inhibitor (Akti inhibitor 1/2) resulted in normalization of the hypermotile phenotype. Thus, our study extends the list of genetic disorders causing podocyte damage and provides the evidence of altered cell signaling cascades resulting in impaired cell adhesion and enhanced cell motility in cystinosis.
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Affiliation(s)
- Ekaterina A Ivanova
- Department of Development and Regeneration, Laboratory of Pediatric Nephrology, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Fanny O Arcolino
- Department of Development and Regeneration, Laboratory of Pediatric Nephrology, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Mohamed A Elmonem
- Department of Development and Regeneration, Laboratory of Pediatric Nephrology, Katholieke Universiteit Leuven, Leuven, Belgium; Department of Clinical and Chemical Pathology, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Maria P Rastaldi
- Renal Research Laboratory, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico and Fondazione D'Amico, Milano, Italy
| | - Laura Giardino
- Renal Research Laboratory, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico and Fondazione D'Amico, Milano, Italy
| | - Elisabeth M Cornelissen
- Department of Pediatric Nephrology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Lambertus P van den Heuvel
- Department of Development and Regeneration, Laboratory of Pediatric Nephrology, Katholieke Universiteit Leuven, Leuven, Belgium; Department of Pediatric Nephrology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Elena N Levtchenko
- Department of Development and Regeneration, Laboratory of Pediatric Nephrology, Katholieke Universiteit Leuven, Leuven, Belgium.
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10
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McEvoy B, Sumayao R, Slattery C, McMorrow T, Newsholme P. Cystine accumulation attenuates insulin release from the pancreatic β-cell due to elevated oxidative stress and decreased ATP levels. J Physiol 2015; 593:5167-82. [PMID: 26482480 DOI: 10.1113/jp271237] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 10/13/2015] [Indexed: 12/26/2022] Open
Abstract
The pancreatic β-cell has reduced antioxidant defences making it more susceptible to oxidative stress. In cystinosis, a lysosomal storage disorder, an altered redox state may contribute to cellular dysfunction. This rare disease is caused by an abnormal lysosomal cystine transporter, cystinosin, which causes excessive accumulation of cystine in the lysosome. Cystinosis associated kidney damage and dysfunction leads to the Fanconi syndrome and ultimately end-stage renal disease. Following kidney transplant, cystine accumulation in other organs including the pancreas leads to multi-organ dysfunction. In this study, a Ctns gene knockdown model of cystinosis was developed in the BRIN-BD11 rat clonal pancreatic β-cell line using Ctns-targeting siRNA. Additionally there was reduced cystinosin expression, while cell cystine levels were similarly elevated to the cystinotic state. Decreased levels of chronic (24 h) and acute (20 min) nutrient-stimulated insulin secretion were observed. This decrease may be due to depressed ATP generation particularly from glycolysis. Increased ATP production and the ATP/ADP ratio are essential for insulin secretion. Oxidised glutathione levels were augmented, resulting in a lower [glutathione/oxidised glutathione] redox potential. Additionally, the mitochondrial membrane potential was reduced, apoptosis levels were elevated, as were markers of oxidative stress, including reactive oxygen species, superoxide and hydrogen peroxide. Furthermore, the basal and activated phosphorylated forms of the redox-sensitive transcription factor NF-κB were increased in cells with silenced Ctns. From this study, the cystinotic-like pancreatic β-cell model demonstrated that the altered oxidative status of the cell, resulted in depressed mitochondrial function and pathways of ATP production, causing reduced nutrient-stimulated insulin secretion.
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Affiliation(s)
- Bernadette McEvoy
- Conway Institute, School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland
| | - Rodolfo Sumayao
- Conway Institute, School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland
| | - Craig Slattery
- Conway Institute, School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland
| | - Tara McMorrow
- Conway Institute, School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland
| | - Philip Newsholme
- School of Biomedical Sciences, CHIRI Biosciences Research Precinct and Faculty of Health Sciences, Curtin University, Perth, Australia
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Endo-lysosomal dysfunction in human proximal tubular epithelial cells deficient for lysosomal cystine transporter cystinosin. PLoS One 2015; 10:e0120998. [PMID: 25811383 PMCID: PMC4374958 DOI: 10.1371/journal.pone.0120998] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 02/09/2015] [Indexed: 12/11/2022] Open
Abstract
Nephropathic cystinosis is a lysosomal storage disorder caused by mutations in the CTNS gene encoding cystine transporter cystinosin that results in accumulation of amino acid cystine in the lysosomes throughout the body and especially affects kidneys. Early manifestations of the disease include renal Fanconi syndrome, a generalized proximal tubular dysfunction. Current therapy of cystinosis is based on cystine-lowering drug cysteamine that postpones the disease progression but offers no cure for the Fanconi syndrome. We studied the mechanisms of impaired reabsorption in human proximal tubular epithelial cells (PTEC) deficient for cystinosin and investigated the endo-lysosomal compartments of cystinosin-deficient PTEC by means of light and electron microscopy. We demonstrate that cystinosin-deficient cells had abnormal shape and distribution of the endo-lysosomal compartments and impaired endocytosis, with decreased surface expression of multiligand receptors and delayed lysosomal cargo processing. Treatment with cysteamine improved surface expression and lysosomal cargo processing but did not lead to a complete restoration and had no effect on the abnormal morphology of endo-lysosomal compartments. The obtained results improve our understanding of the mechanism of proximal tubular dysfunction in cystinosis and indicate that impaired protein reabsorption can, at least partially, be explained by abnormal trafficking of endosomal vesicles.
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Emma F, Nesterova G, Langman C, Labbé A, Cherqui S, Goodyer P, Janssen MC, Greco M, Topaloglu R, Elenberg E, Dohil R, Trauner D, Antignac C, Cochat P, Kaskel F, Servais A, Wühl E, Niaudet P, Van't Hoff W, Gahl W, Levtchenko E. Nephropathic cystinosis: an international consensus document. Nephrol Dial Transplant 2014; 29 Suppl 4:iv87-94. [PMID: 25165189 DOI: 10.1093/ndt/gfu090] [Citation(s) in RCA: 126] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Cystinosis is caused by mutations in the CTNS gene (17p13.2), which encodes for a lysosomal cystine/proton symporter termed cystinosin. It is the most common cause of inherited renal Fanconi syndrome in young children. Because of its rarity, the diagnosis and specific treatment of cystinosis are frequently delayed, which has a significant impact on the overall prognosis. In this document, we have summarized expert opinions on several aspects of the disease to improve knowledge and provide guidance for diagnosis and treatment.
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Affiliation(s)
- Francesco Emma
- Division of Nephrology and Dialysis, Bambino Gesu` Children's Hospital - IRCCS, Rome, Italy
| | - Galina Nesterova
- Section on Human Biochemical Genetics, Human Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892-1851, USA
| | - Craig Langman
- Kidney Diseases, Feinberg School of Medicine, Northwestern University and the Ann and Robert H Lurie Children's Hospital of Chicago, Chicago, IL, USA
| | - Antoine Labbé
- Quinze-Vingts National Ophthalmology Hospital, Paris and Versailles Saint-Quentin-en-Yvelines University, Versailles, France Clinical Investigations Center, INSERM 503, Quinze-Vingts National Ophthalmology Hospital, Paris, France
| | - Stephanie Cherqui
- Division of Genetics, Department of Pediatrics, University of California, San Diego, La Jolla, CA, USA
| | - Paul Goodyer
- Department of Pediatrics, McGill University, Montreal Children's Hospital, Montreal, Québec, Canada
| | - Mirian C Janssen
- Department of Internal Medicine, Radboud University Medical Centre Nijmegen, Nijmegen, The Netherlands
| | - Marcella Greco
- Division of Nephrology and Dialysis, Bambino Gesu` Children's Hospital - IRCCS, Rome, Italy
| | - Rezan Topaloglu
- Division of Pediatric Nephrology, Department of Pediatrics, Hacettepe University Faculty of Medicine, Ankara, Turkey
| | - Ewa Elenberg
- Renal Service, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, USA
| | - Ranjan Dohil
- Department of Pediatrics, Rady Children's Hospital, San Diego, University of California San Diego, San Diego, CA, USA
| | - Doris Trauner
- Department of Neurosciences, University of California, San Diego, School of Medicine, San Diego, CA, USA
| | - Corinne Antignac
- Laboratory of Inherited Kidney Diseases, Inserm UMR 1163, Paris, France Paris Descartes-Sorbonne Paris Cité University, Imagine Institute, Paris, France APHP, Department of Genetics, Necker Hospital, Paris, France
| | - Pierre Cochat
- Centre de référence des maladies rénales rares, Hospices Civils de Lyon and Université Claude-Bernard Lyon 1, Lyon, France
| | - Frederick Kaskel
- Pediatric Nephrology, Children's Hospital at Montefiore, Bronx, NY, USA
| | - Aude Servais
- Department of Adult Nephrology, Hôpital Necker-Enfants Malades, APHP, Paris Descartes University, Paris, France
| | - Elke Wühl
- Division of Pediatric Nephrology, Center of Pediatrics and Adolescent Medicine, University of Heidelberg, Heidelberg, Germany
| | - Patrick Niaudet
- Université Paris Descartes, Hôpital Necker-Enfants Malades, Paris 75015, France
| | | | - William Gahl
- Section on Human Biochemical Genetics, Human Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892-1851, USA
| | - Elena Levtchenko
- Department of Pediatric Nephrology and Growth and Regeneration, University Hospitals Leuven, Katholieke Universiteit Leuven, Leuven, Belgium
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Taatjes DJ, Roth J. The Histochemistry and Cell Biology compendium: a review of 2012. Histochem Cell Biol 2013; 139:815-46. [PMID: 23665922 DOI: 10.1007/s00418-013-1098-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/29/2013] [Indexed: 01/27/2023]
Abstract
The year 2012 was another exciting year for Histochemistry and Cell Biology. Innovations in immunohistochemical techniques and microscopy-based imaging have provided the means for advances in the field of cell biology. Over 130 manuscripts were published in the journal during 2012, representing methodological advancements, pathobiology of disease, and cell and tissue biology. This annual review of the manuscripts published in the previous year in Histochemistry and Cell Biology serves as an abbreviated reference for the readership to quickly peruse and discern trends in the field over the past year. The review has been broadly divided into multiple sections encompassing topics such as method advancements, subcellular components, extracellular matrix, and organ systems. We hope that the creation of this subdivision will serve to guide the reader to a specific topic of interest, while simultaneously providing a concise and easily accessible encapsulation of other topics in the broad area of Histochemistry and Cell Biology.
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Affiliation(s)
- Douglas J Taatjes
- Department of Pathology and Microscopy Imaging Center, University of Vermont College of Medicine, 89 Beaumont Avenue, Burlington, VT 05405, USA.
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