1
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Saffie-Siebert S, Alam I, Sutera FM, Dehsorkhi A, Torabi-Pour N, Baran-Rachwalska P, Iamartino L, Teti A, Maurizi A, Gerard-O'Riley RL, Acton D, Econs MJ. Effect of Allele-Specific Clcn7 G213R siRNA Delivered Via a Novel Nanocarrier on Bone Phenotypes in ADO2 Mice on 129S Background. Calcif Tissue Int 2024; 115:85-96. [PMID: 38733412 DOI: 10.1007/s00223-024-01222-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Accepted: 04/18/2024] [Indexed: 05/13/2024]
Abstract
Autosomal dominant osteopetrosis type 2 (ADO2) is a rare inherited bone disorder characterised by dense but brittle bones. It displays striking phenotypic variability, with the most severe symptoms, including blindness and bone marrow failure. Disease management largely relies on symptomatic treatment since there is no safe and effective treatment. Most ADO2 cases are caused by heterozygous loss-of-function mutations in the CLCN7 gene, which encodes an essential Cl-/H+ antiporter for proper bone resorption by osteoclasts. Thus, siRNA-mediated silencing of the mutant allele is a promising therapeutic approach, but targeting bone for first-in-human translation remains challenging. Here, we demonstrate the utility of silicon-stabilised hybrid lipid nanoparticles (sshLNPs) as a next-generation nucleic acid nanocarrier capable of delivering allele-specific siRNA to bone. Using a Clcn7G213R knock-in mouse model recapitulating one of the most common human ADO2 mutations and based on the 129S genetic background (which produces the most severe disease phenotype amongst current models), we show substantial knockdown of the mutant allele in femur when siRNA targeting the pathogenic variant is delivered by sshLNPs. We observed lower areal bone mineral density in femur and reduced trabecular thickness in femur and tibia, when siRNA-loaded sshLNPs were administered subcutaneously (representing the most relevant administration route for clinical adoption and patient adherence). Importantly, sshLNPs have improved stability over conventional LNPs and enable 'post hoc loading' for point-of-care formulation. The treatment was well tolerated, suggesting that sshLNP-enabled gene therapy might allow successful clinical translation of essential new treatments for ADO2 and potentially other rare genetic bone diseases.
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Affiliation(s)
| | - Imranul Alam
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
| | | | | | | | | | | | - Anna Teti
- Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, 67100, L'Aquila, Italy
| | - Antonio Maurizi
- Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, 67100, L'Aquila, Italy
| | - Rita L Gerard-O'Riley
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Dena Acton
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Michael J Econs
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
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2
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Polovitskaya MM, Rana T, Ullrich K, Murko S, Bierhals T, Vogt G, Stauber T, Kubisch C, Santer R, Jentsch TJ. Gain-of-function variants in CLCN7 cause hypopigmentation and lysosomal storage disease. J Biol Chem 2024; 300:107437. [PMID: 38838776 PMCID: PMC11261146 DOI: 10.1016/j.jbc.2024.107437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Revised: 05/08/2024] [Accepted: 05/23/2024] [Indexed: 06/07/2024] Open
Abstract
Together with its β-subunit OSTM1, ClC-7 performs 2Cl-/H+ exchange across lysosomal membranes. Pathogenic variants in either gene cause lysosome-related pathologies, including osteopetrosis and lysosomal storage. CLCN7 variants can cause recessive or dominant disease. Different variants entail different sets of symptoms. Loss of ClC-7 causes osteopetrosis and mostly neuronal lysosomal storage. A recently reported de novo CLCN7 mutation (p.Tyr715Cys) causes widespread severe lysosome pathology (hypopigmentation, organomegaly, and delayed myelination and development, "HOD syndrome"), but no osteopetrosis. We now describe two additional HOD individuals with the previously described p.Tyr715Cys and a novel p.Lys285Thr mutation, respectively. Both mutations decreased ClC-7 inhibition by PI(3,5)P2 and affected residues lining its binding pocket, and shifted voltage-dependent gating to less positive potentials, an effect partially conferred to WT subunits in WT/mutant heteromers. This shift predicts augmented pH gradient-driven Cl- uptake into vesicles. Overexpressing either mutant induced large lysosome-related vacuoles. This effect depended on Cl-/H+-exchange, as shown using mutants carrying uncoupling mutations. Fibroblasts from the p.Y715C patient also displayed giant vacuoles. This was not observed with p.K285T fibroblasts probably due to residual PI(3,5)P2 sensitivity. The gain of function caused by the shifted voltage-dependence of either mutant likely is the main pathogenic factor. Loss of PI(3,5)P2 inhibition will further increase current amplitudes, but may not be a general feature of HOD. Overactivity of ClC-7 induces pathologically enlarged vacuoles in many tissues, which is distinct from lysosomal storage observed with the loss of ClC-7 function. Osteopetrosis results from a loss of ClC-7, but osteoclasts remain resilient to increased ClC-7 activity.
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Affiliation(s)
- Maya M Polovitskaya
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Tanushka Rana
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany; Graduate program of Humboldt-Universität zu Berlin and Graduate School of the Max Delbrück Centre for Molecular Medicine (MDC), Berlin, Germany
| | - Kurt Ullrich
- Department of Pediatrics, University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Simona Murko
- Department of Pediatrics, University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Tatjana Bierhals
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Guido Vogt
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Tobias Stauber
- Institute for Molecular Medicine, Medical School Hamburg (MSH), Hamburg, Germany
| | - Christian Kubisch
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - René Santer
- Department of Pediatrics, University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany.
| | - Thomas J Jentsch
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany; NeuroCure Cluster of Excellence, Charité Universitätsmedizin, Berlin, Germany.
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3
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Cen J, Hu N, Shen J, Gao Y, Lu H. Pathological Functions of Lysosomal Ion Channels in the Central Nervous System. Int J Mol Sci 2024; 25:6565. [PMID: 38928271 PMCID: PMC11203704 DOI: 10.3390/ijms25126565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Revised: 06/06/2024] [Accepted: 06/10/2024] [Indexed: 06/28/2024] Open
Abstract
Lysosomes are highly dynamic organelles that maintain cellular homeostasis and regulate fundamental cellular processes by integrating multiple metabolic pathways. Lysosomal ion channels such as TRPML1-3, TPC1/2, ClC6/7, CLN7, and TMEM175 mediate the flux of Ca2+, Cl-, Na+, H+, and K+ across lysosomal membranes in response to osmotic stimulus, nutrient-dependent signals, and cellular stresses. These ion channels serve as the crucial transducers of cell signals and are essential for the regulation of lysosomal biogenesis, motility, membrane contact site formation, and lysosomal homeostasis. In terms of pathophysiology, genetic variations in these channel genes have been associated with the development of lysosomal storage diseases, neurodegenerative diseases, inflammation, and cancer. This review aims to discuss the current understanding of the role of these ion channels in the central nervous system and to assess their potential as drug targets.
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Affiliation(s)
| | | | | | - Yongjing Gao
- Institute of Pain Medicine and Special Environmental Medicine, Co-Innovation Center of Neuroregeneration, Nantong University, Nantong 226019, China; (J.C.); (N.H.); (J.S.)
| | - Huanjun Lu
- Institute of Pain Medicine and Special Environmental Medicine, Co-Innovation Center of Neuroregeneration, Nantong University, Nantong 226019, China; (J.C.); (N.H.); (J.S.)
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4
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Bose S, de Heus C, Kennedy ME, Wang F, Jentsch TJ, Klumperman J, Stauber T. Impaired Autophagic Clearance with a Gain-of-Function Variant of the Lysosomal Cl -/H + Exchanger ClC-7. Biomolecules 2023; 13:1799. [PMID: 38136669 PMCID: PMC10742274 DOI: 10.3390/biom13121799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 12/04/2023] [Accepted: 12/07/2023] [Indexed: 12/24/2023] Open
Abstract
ClC-7 is a ubiquitously expressed voltage-gated Cl-/H+ exchanger that critically contributes to lysosomal ion homeostasis. Together with its β-subunit Ostm1, ClC-7 localizes to lysosomes and to the ruffled border of osteoclasts, where it supports the acidification of the resorption lacuna. Loss of ClC-7 or Ostm1 leads to osteopetrosis accompanied by accumulation of storage material in lysosomes and neurodegeneration. Interestingly, not all osteopetrosis-causing CLCN7 mutations from patients are associated with a loss of ion transport. Some rather result in an acceleration of voltage-dependent ClC-7 activation. Recently, a gain-of-function variant, ClC-7Y715C, that yields larger ion currents upon heterologous expression, was identified in two patients with neurodegeneration, organomegaly and albinism. However, neither the patients nor a mouse model that carried the equivalent mutation developed osteopetrosis, although expression of ClC-7Y715C induced the formation of enlarged intracellular vacuoles. Here, we investigated how, in transfected cells with mutant ClC-7, the substitution of this tyrosine impinged on the morphology and function of lysosomes. Combinations of the tyrosine mutation with mutations that either uncouple Cl- from H+ counter-transport or strongly diminish overall ion currents were used to show that increased ClC-7 Cl-/H+ exchange activity is required for the formation of enlarged vacuoles by membrane fusion. Degradation of endocytosed material was reduced in these compartments and resulted in an accumulation of lysosomal storage material. In cells expressing the ClC-7 gain-of-function mutant, autophagic clearance was largely impaired, resulting in a build-up of autophagic material.
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Affiliation(s)
- Shroddha Bose
- Institute for Molecular Medicine, MSH Medical School Hamburg, 20457 Hamburg, Germany
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, 14195 Berlin, Germany
| | - Cecilia de Heus
- Center for Molecular Medicine/Cell Biology, University Medical Center (UMC), 3584 CX Utrecht, The Netherlands
| | - Mary E. Kennedy
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, 14195 Berlin, Germany
| | - Fan Wang
- Institute for Molecular Medicine, MSH Medical School Hamburg, 20457 Hamburg, Germany
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, 14195 Berlin, Germany
| | - Thomas J. Jentsch
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), 13125 Berlin, Germany
- NeuroCure Cluster of Excellence, Charité Universitätsmedizin Berlin, 10117 Berlin, Germany
| | - Judith Klumperman
- Center for Molecular Medicine/Cell Biology, University Medical Center (UMC), 3584 CX Utrecht, The Netherlands
| | - Tobias Stauber
- Institute for Molecular Medicine, MSH Medical School Hamburg, 20457 Hamburg, Germany
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, 14195 Berlin, Germany
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5
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Marunaka Y. Physiological roles of chloride ions in bodily and cellular functions. J Physiol Sci 2023; 73:31. [PMID: 37968609 PMCID: PMC10717538 DOI: 10.1186/s12576-023-00889-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Accepted: 10/31/2023] [Indexed: 11/17/2023]
Abstract
Physiological roles of Cl-, a major anion in the body, are not well known compared with those of cations. This review article introduces: (1) roles of Cl- in bodily and cellular functions; (2) the range of cytosolic Cl- concentration ([Cl-]c); (3) whether [Cl-]c could change with cell volume change under an isosmotic condition; (4) whether [Cl-]c could change under conditions where multiple Cl- transporters and channels contribute to Cl- influx and efflux in an isosmotic state; (5) whether the change in [Cl-]c could be large enough to act as signals; (6) effects of Cl- on cytoskeletal tubulin polymerization through inhibition of GTPase activity and tubulin polymerization-dependent biological activity; (7) roles of cytosolic Cl- in cell proliferation; (8) Cl--regulatory mechanisms of ciliary motility; (9) roles of Cl- in sweet/umami taste receptors; (10) Cl--regulatory mechanisms of with-no-lysine kinase (WNK); (11) roles of Cl- in regulation of epithelial Na+ transport; (12) relationship between roles of Cl- and H+ in body functions.
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Affiliation(s)
- Yoshinori Marunaka
- Medical Research Institute, Kyoto Industrial Health Association, General Incorporated Foundation, 67 Kitatsuboi-Cho, Nishinokyo, Nakagyo-Ku, Kyoto, 604-8472, Japan.
- Research Organization of Science and Technology, Ritsumeikan University, Kusatsu, 525-8577, Japan.
- Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kamigyo-Ku, Kyoto, 602-8566, Japan.
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6
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Cao X, Lenk GM, Mikusevic V, Mindell JA, Meisler MH. The chloride antiporter CLCN7 is a modifier of lysosome dysfunction in FIG 4 and VAC14 mutants. PLoS Genet 2023; 19:e1010800. [PMID: 37363915 DOI: 10.1371/journal.pgen.1010800] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Accepted: 05/26/2023] [Indexed: 06/28/2023] Open
Abstract
The phosphatase FIG 4 and the scaffold protein VAC14 function in the biosynthesis of PI(3,5)P2, a signaling lipid that inhibits the lysosomal chloride transporter ClC-7. Loss-of-function mutations of FIG 4 and VAC14 reduce PI(3,5)P2 and result in lysosomal disorders characterized by accumulation of enlarged lysosomes and neurodegeneration. Similarly, a gain of function mutation of CLCN7 encoding ClC-7 also results in enlarged lysosomes. We therefore tested the ability of reduced CLCN7 expression to compensate for loss of FIG 4 or VAC14. Knock-out of CLCN7 corrected lysosomal swelling and partially corrected lysosomal hyperacidification in FIG 4 null cell cultures. Knockout of the related transporter CLCN6 (ClC-6) in FIG 4 null cells did not affect the lysosome phenotype. In the Fig 4 null mouse, reduction of ClC-7 by expression of the dominant negative CLCN7 variant p.Gly215Arg improved growth and neurological function and increased lifespan by 20%. These observations demonstrate a role for the CLCN7 chloride transporter in pathogenesis of FIG 4 and VAC14 disorders. Reduction of CLCN7 provides a new target for treatment of FIG 4 and VAC14 deficiencies that lack specific therapies, such as Charcot-Marie-Tooth Type 4J and Yunis-Varón syndrome.
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Affiliation(s)
- Xu Cao
- Department of Human Genetics, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Guy M Lenk
- Department of Human Genetics, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Vedrana Mikusevic
- Membrane Transport Biophysics Section, National Institutes of Neurological Disorders and Stroke, Bethesda, Maryland, United States of America
| | - Joseph A Mindell
- Membrane Transport Biophysics Section, National Institutes of Neurological Disorders and Stroke, Bethesda, Maryland, United States of America
| | - Miriam H Meisler
- Department of Human Genetics, University of Michigan, Ann Arbor, Michigan, United States of America
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7
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Zhang Q, Li Y, Jian Y, Li M, Wang X. Lysosomal chloride transporter CLH-6 protects lysosome membrane integrity via cathepsin activation. J Cell Biol 2023; 222:e202210063. [PMID: 37058288 PMCID: PMC10114921 DOI: 10.1083/jcb.202210063] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 02/11/2023] [Accepted: 03/10/2023] [Indexed: 04/15/2023] Open
Abstract
Lysosomal integrity is vital for cell homeostasis, but the underlying mechanisms are poorly understood. Here, we identify CLH-6, the C. elegans ortholog of the lysosomal Cl-/H+ antiporter ClC-7, as an important factor for protecting lysosomal integrity. Loss of CLH-6 affects lysosomal degradation, causing cargo accumulation and membrane rupture. Reducing cargo delivery or increasing CPL-1/cathepsin L or CPR-2/cathepsin B expression suppresses these lysosomal defects. Inactivation of CPL-1 or CPR-2, like CLH-6 inactivation, affects cargo digestion and causes lysosomal membrane rupture. Thus, loss of CLH-6 impairs cargo degradation, leading to membrane damage of lysosomes. In clh-6(lf) mutants, lysosomes are acidified as in wild type but contain lower chloride levels, and cathepsin B and L activities are significantly reduced. Cl- binds to CPL-1 and CPR-2 in vitro, and Cl- supplementation increases lysosomal cathepsin B and L activities. Altogether, these findings suggest that CLH-6 maintains the luminal chloride levels required for cathepsin activity, thus facilitating substrate digestion to protect lysosomal membrane integrity.
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Affiliation(s)
- Qianqian Zhang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Yuan Li
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Youli Jian
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Meijiao Li
- State Key Laboratory of Conservation and Utilization of Bio-Resources in Yunnan, and Center for Life Sciences, School of Life Sciences, Yunnan University, Kunming, China
| | - Xiaochen Wang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
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8
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Wu JZ, Zeziulia M, Kwon W, Jentsch TJ, Grinstein S, Freeman SA. ClC-7 drives intraphagosomal chloride accumulation to support hydrolase activity and phagosome resolution. J Cell Biol 2023; 222:e202208155. [PMID: 37010469 PMCID: PMC10072274 DOI: 10.1083/jcb.202208155] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 02/22/2023] [Accepted: 03/17/2023] [Indexed: 04/04/2023] Open
Abstract
Degradative organelles contain enzymes that function optimally at the acidic pH generated by the V-ATPase. The resulting transmembrane H+ gradient also energizes the secondary transport of several solutes, including Cl-. We report that Cl- influx, driven by the 2Cl-/H+ exchanger ClC-7, is necessary for the resolution of phagolysosomes formed by macrophages. Cl- transported via ClC-7 had been proposed to provide the counterions required for electrogenic H+ pumping. However, we found that deletion of ClC-7 had a negligible effect on phagosomal acidification. Instead, luminal Cl- was found to be required for activation of a wide range of phagosomal hydrolases including proteases, nucleases, and glycosidases. These findings argue that the primary role of ClC-7 is the accumulation of (phago)lysosomal Cl- and that the V-ATPases not only optimize the activity of degradative hydrolases by lowering the pH but, importantly, also play an indirect role in their activation by providing the driving force for accumulation of luminal Cl- that stimulates hydrolase activity allosterically.
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Affiliation(s)
- Jing Ze Wu
- Program in Cell Biology, Hospital for Sick Children, Toronto, Canada
- Department of Biochemistry, University of Toronto, Toronto, Canada
| | - Mariia Zeziulia
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie and Max-Delbrück-Centrum für Molekulare Medizin, Berlin, Germany
- Graduate Program of the Freie Universität Berlin, Berlin, Germany
| | - Whijin Kwon
- Program in Cell Biology, Hospital for Sick Children, Toronto, Canada
| | - Thomas J. Jentsch
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie and Max-Delbrück-Centrum für Molekulare Medizin, Berlin, Germany
- NeuroCure Cluster of Excellence, Charité University Medicine Berlin, Berlin, Germany
| | - Sergio Grinstein
- Program in Cell Biology, Hospital for Sick Children, Toronto, Canada
- Department of Biochemistry, University of Toronto, Toronto, Canada
| | - Spencer A. Freeman
- Program in Cell Biology, Hospital for Sick Children, Toronto, Canada
- Department of Biochemistry, University of Toronto, Toronto, Canada
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9
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Coppola MA, Tettey-Matey A, Imbrici P, Gavazzo P, Liantonio A, Pusch M. Biophysical Aspects of Neurodegenerative and Neurodevelopmental Disorders Involving Endo-/Lysosomal CLC Cl -/H + Antiporters. Life (Basel) 2023; 13:1317. [PMID: 37374100 DOI: 10.3390/life13061317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 05/30/2023] [Accepted: 05/31/2023] [Indexed: 06/29/2023] Open
Abstract
Endosomes and lysosomes are intracellular vesicular organelles with important roles in cell functions such as protein homeostasis, clearance of extracellular material, and autophagy. Endolysosomes are characterized by an acidic luminal pH that is critical for proper function. Five members of the gene family of voltage-gated ChLoride Channels (CLC proteins) are localized to endolysosomal membranes, carrying out anion/proton exchange activity and thereby regulating pH and chloride concentration. Mutations in these vesicular CLCs cause global developmental delay, intellectual disability, various psychiatric conditions, lysosomal storage diseases, and neurodegeneration, resulting in severe pathologies or even death. Currently, there is no cure for any of these diseases. Here, we review the various diseases in which these proteins are involved and discuss the peculiar biophysical properties of the WT transporter and how these properties are altered in specific neurodegenerative and neurodevelopmental disorders.
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Affiliation(s)
- Maria Antonietta Coppola
- Istituto di Biofisica, Consiglio Nazionale delle Ricerche, 16149 Genova, Italy
- Department of Pharmacy-Drug Sciences, University of Bari "Aldo Moro", 70125 Bari, Italy
| | | | - Paola Imbrici
- Department of Pharmacy-Drug Sciences, University of Bari "Aldo Moro", 70125 Bari, Italy
| | - Paola Gavazzo
- Istituto di Biofisica, Consiglio Nazionale delle Ricerche, 16149 Genova, Italy
| | - Antonella Liantonio
- Department of Pharmacy-Drug Sciences, University of Bari "Aldo Moro", 70125 Bari, Italy
| | - Michael Pusch
- Istituto di Biofisica, Consiglio Nazionale delle Ricerche, 16149 Genova, Italy
- RAISE Ecosystem, 16149 Genova, Italy
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10
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Levin-Konigsberg R, Mitra K, Nigam A, Spees K, Hivare P, Liu K, Kundaje A, Krishnan Y, Bassik MC. SLC12A9 is a lysosome-detoxifying ammonium - chloride co-transporter. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.22.541801. [PMID: 37292735 PMCID: PMC10245881 DOI: 10.1101/2023.05.22.541801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Ammonia is a ubiquitous, toxic by-product of cell metabolism. Its high membrane permeability and proton affinity causes ammonia to accumulate inside acidic lysosomes in its poorly membrane-permeant form: ammonium (NH 4 + ). Ammonium buildup compromises lysosomal function, suggesting the existence of mechanisms that protect cells from ammonium toxicity. Here, we identified SLC12A9 as a lysosomal ammonium exporter that preserves lysosomal homeostasis. SLC12A9 knockout cells showed grossly enlarged lysosomes and elevated ammonium content. These phenotypes were reversed upon removal of the metabolic source of ammonium or dissipation of the lysosomal pH gradient. Lysosomal chloride increased in SLC12A9 knockout cells and chloride binding by SLC12A9 was required for ammonium transport. Our data indicate that SLC12A9 is a chloride-driven ammonium co-transporter that is central in an unappreciated, fundamental mechanism of lysosomal physiology that may have special relevance in tissues with elevated ammonia, such as tumors.
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11
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Seliverstova EV, Prutskova NP. Renal protein reabsorption impairment related to a myxosporean infection in the grass frog (Rana temporaria L.). Parasitol Res 2023; 122:1303-1316. [PMID: 37012507 DOI: 10.1007/s00436-023-07830-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 03/24/2023] [Indexed: 04/05/2023]
Abstract
A morphophysiological study of tubular reabsorption and mechanisms of protein endocytosis in the kidney of frogs (Rana temporaria L.) during parasitic infection was carried out. Pseudoplasmodia and spores of myxosporidia, beforehand assigned to the genus Sphaerospora, were detected in Bowman's capsules and in the lumen of individual renal tubules by light and electron microscopy. Remarkable morphological alteration and any signs of pathology in kidney tissue related to this myxosporean infection have not been noted. At the same time, significant changes in protein reabsorption and distribution of molecular markers of endocytosis in the proximal tubule (PT) cells in infected animals were detected by immunofluorescence confocal microscopy. In lysozyme injection experiments, the endocytosed protein and megalin expression in the infected PTs were not revealed. Tubular expression of cubilin and clathrin decreased, but endosomal recycling marker Rab11 increased or remained unchanged. Thus, myxosporean infection resulted in the alterations in lysozyme uptake and expression of the main molecular determinants of endocytosis. The inhibition of receptor-mediated clathrin-dependent protein endocytosis in amphibian kidneys due to myxosporidiosis was shown for the first time. Established impairment of the endocytic process is a clear marker of tubular cell dysfunction that can be used to assess the functioning of amphibian kidneys during adaptation to adverse environmental factors.
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Affiliation(s)
- Elena V Seliverstova
- Laboratory of Renal Physiology, Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences, Torez Av., 44, Saint Petersburg, 194223, Russian Federation.
| | - Natalya P Prutskova
- Laboratory of Renal Physiology, Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences, Torez Av., 44, Saint Petersburg, 194223, Russian Federation
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12
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Mendes LC, Viana GMM, Nencioni ALA, Pimenta DC, Beraldo-Neto E. Scorpion Peptides and Ion Channels: An Insightful Review of Mechanisms and Drug Development. Toxins (Basel) 2023; 15:238. [PMID: 37104176 PMCID: PMC10145618 DOI: 10.3390/toxins15040238] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 03/21/2023] [Accepted: 03/22/2023] [Indexed: 04/28/2023] Open
Abstract
The Buthidae family of scorpions consists of arthropods with significant medical relevance, as their venom contains a diverse range of biomolecules, including neurotoxins that selectively target ion channels in cell membranes. These ion channels play a crucial role in regulating physiological processes, and any disturbance in their activity can result in channelopathies, which can lead to various diseases such as autoimmune, cardiovascular, immunological, neurological, and neoplastic conditions. Given the importance of ion channels, scorpion peptides represent a valuable resource for developing drugs with targeted specificity for these channels. This review provides a comprehensive overview of the structure and classification of ion channels, the action of scorpion toxins on these channels, and potential avenues for future research. Overall, this review highlights the significance of scorpion venom as a promising source for discovering novel drugs with therapeutic potential for treating channelopathies.
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Affiliation(s)
- Lais Campelo Mendes
- Programa de Pós-Graduação em Ciências—Toxinologia do Instituto Butantan, São Paulo 05503-900, Brazil
- Laboratório de Bioquímica do Instituto Butantan, São Paulo 05503-900, Brazil
| | | | | | | | - Emidio Beraldo-Neto
- Laboratório de Bioquímica do Instituto Butantan, São Paulo 05503-900, Brazil
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13
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Stauber T, Wartosch L, Vishnolia S, Schulz A, Kornak U. CLCN7, a gene shared by autosomal recessive and autosomal dominant osteopetrosis. Bone 2023; 168:116639. [PMID: 36513280 DOI: 10.1016/j.bone.2022.116639] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 11/27/2022] [Accepted: 11/30/2022] [Indexed: 12/14/2022]
Abstract
After the discovery of abundant v-ATPase complexes in the osteoclast ruffled membrane it was obvious that in parallel a negative counter-ion needs to be transported across this membrane to allow for efficient transport of protons into the resorption lacuna. While different candidate proteins were discussed the osteopetrosis phenotype of Clcn7 knockout mice suggested that the chloride/proton-exchanger ClC-7 might be responsible for transporting the negative charge. In the following, individuals with autosomal recessive osteopetrosis (ARO) were found to carry biallelic CLCN7 pathogenic variants. Shortly thereafter, heterozygous pathogenic variants were identified as the exclusive cause of autosomal dominant osteopetrosis type 2 (ADO2). Since in most cell types other than osteoclasts ClC-7 resides in late endosomes and lysosomes, it took some time until the electrophysiological properties of ClC-7 were elucidated. Whereas most missense variants lead to reduced chloride currents, several variants with accelerated kinetics have been identified. Evidence for folding problems is also known for several missense variants. Paradoxically, a heterozygous activating variant in ClC-7 was described to cause lysosomal alteration, pigmentation defects, and intellectual disability without osteopetrosis. The counter-intuitive 2 Cl-/H+ exchange function of ClC-7 was shown to be physiologically important for intravesicular ion homeostasis. The lysosomal function of ClC-7 is also the reason why individuals with CLCN7-ARO can develop a storage disorder and neurodegeneration, a feature that is variable and difficult to predict. Furthermore, the low penetrance of heterozygous pathogenic CLCN7 variants and the clinical variability of ADO2 are incompletely understood. We aim to give an overview not only of the current knowledge about ClC-7 and its related pathologies, but also of the scientists and clinicians that paved the way for these discoveries.
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Affiliation(s)
- Tobias Stauber
- Institute for Molecular Medicine, MSH Medical School Hamburg, Hamburg, Germany
| | - Lena Wartosch
- Department of Meiosis, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Svenja Vishnolia
- Institute of Human Genetics, University Medical Center Göttingen, Göttingen, Germany
| | - Ansgar Schulz
- Department of Pediatrics and Adolescent Medicine, University Medical Center Ulm, Ulm, Germany
| | - Uwe Kornak
- Institute of Human Genetics, University Medical Center Göttingen, Göttingen, Germany.
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14
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Riederer E, Cang C, Ren D. Lysosomal Ion Channels: What Are They Good For and Are They Druggable Targets? Annu Rev Pharmacol Toxicol 2023; 63:19-41. [PMID: 36151054 DOI: 10.1146/annurev-pharmtox-051921-013755] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Lysosomes play fundamental roles in material digestion, cellular clearance, recycling, exocytosis, wound repair, Ca2+ signaling, nutrient signaling, and gene expression regulation. The organelle also serves as a hub for important signaling networks involving the mTOR and AKT kinases. Electrophysiological recording and molecular and structural studies in the past decade have uncovered several unique lysosomal ion channels and transporters, including TPCs, TMEM175, TRPMLs, CLN7, and CLC-7. They underlie the organelle's permeability to major ions, including K+, Na+, H+, Ca2+, and Cl-. The channels are regulated by numerous cellular factors, ranging from H+ in the lumen and voltage across the lysosomal membrane to ATP in the cytosol to growth factors outside the cell. Genetic variations in the channel/transporter genes are associated with diseases that include lysosomal storage diseases and neurodegenerative diseases. Recent studies with human genetics and channel activators suggest that lysosomal channels may be attractive targets for the development of therapeutics for the prevention of and intervention in human diseases.
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Affiliation(s)
- Erika Riederer
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, USA; ,
| | - Chunlei Cang
- CAS Key Laboratory of Innate Immunity and Chronic Disease, Neurodegenerative Disorder Research Center, School of Basic Medical Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, China;
| | - Dejian Ren
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, USA; ,
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15
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López-Cayuqueo KI, Planells-Cases R, Pietzke M, Oliveras A, Kempa S, Bachmann S, Jentsch TJ. Renal Deletion of LRRC8/VRAC Channels Induces Proximal Tubulopathy. J Am Soc Nephrol 2022; 33:1528-1545. [PMID: 35777784 PMCID: PMC9342636 DOI: 10.1681/asn.2021111458] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 05/13/2022] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND Volume-regulated anion channels (VRACs) are heterohexamers of LRRC8A with LRRC8B, -C, -D, or -E in various combinations. Depending on the subunit composition, these swelling-activated channels conduct chloride, amino acids, organic osmolytes, and drugs. Despite VRACs' role in cell volume regulation, and large osmolarity changes in the kidney, neither the localization nor the function of VRACs in the kidney is known. METHODS Mice expressing epitope-tagged LRRC8 subunits were used to determine the renal localization of all VRAC subunits. Mice carrying constitutive deletions of Lrrc8b-e, or with inducible or cell-specific ablation of Lrrc8a, were analyzed to assess renal functions of VRACs. Analysis included histology, urine and serum parameters in different diuresis states, and metabolomics. RESULTS The kidney expresses all five VRAC subunits with strikingly distinct localization. Whereas LRRC8C is exclusively found in vascular endothelium, all other subunits are found in the nephron. LRRC8E is specific for intercalated cells, whereas LRRC8A, LRRC8B, and LRRC8D are prominent in basolateral membranes of proximal tubules. Conditional deletion of LRRC8A in proximal but not distal tubules and constitutive deletion of LRRC8D cause proximal tubular injury, increased diuresis, and mild Fanconi-like symptoms. CONCLUSIONS VRAC/LRRC8 channels are crucial for the function and integrity of proximal tubules, but not for more distal nephron segments despite their larger need for volume regulation. LRRC8A/D channels may be required for the basolateral exit of many organic compounds, including cellular metabolites, in proximal tubules. Proximal tubular injury likely results from combined accumulation of several transported molecules in the absence of VRAC channels.
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Affiliation(s)
- Karen I. López-Cayuqueo
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin (MDC), Berlin, Germany
| | - Rosa Planells-Cases
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin (MDC), Berlin, Germany
| | - Matthias Pietzke
- Integrative Metabolomics and Proteomics, Berlin Institute of Medical Systems Biology/Max-Delbrück-Centrum für Molekulare Medizin, Berlin, Germany
| | - Anna Oliveras
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin (MDC), Berlin, Germany
| | - Stefan Kempa
- Integrative Metabolomics and Proteomics, Berlin Institute of Medical Systems Biology/Max-Delbrück-Centrum für Molekulare Medizin, Berlin, Germany
| | - Sebastian Bachmann
- Department of Anatomy, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Thomas J. Jentsch
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin (MDC), Berlin, Germany,NeuroCure Centre of Excellence, Charité Universitätsmedizin Berlin, Berlin, Germany
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16
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Leray X, Hilton JK, Nwangwu K, Becerril A, Mikusevic V, Fitzgerald G, Amin A, Weston MR, Mindell JA. Tonic inhibition of the chloride/proton antiporter ClC-7 by PI(3,5)P2 is crucial for lysosomal pH maintenance. eLife 2022; 11:74136. [PMID: 35670560 PMCID: PMC9242644 DOI: 10.7554/elife.74136] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Accepted: 06/06/2022] [Indexed: 11/13/2022] Open
Abstract
The acidic luminal pH of lysosomes, maintained within a narrow range, is essential for proper degrative function of the organelle and is generated by the action of a V-type H+ ATPase, but other pathways for ion movement are required to dissipate the voltage generated by this process. ClC-7, a Cl-/H+ antiporter responsible for lysosomal Cl- permeability, is a candidate to contribute to the acidification process as part of this ‘counterion pathway’ The signaling lipid PI(3,5)P2 modulates lysosomal dynamics, including by regulating lysosomal ion channels, raising the possibility that it could contribute to lysosomal pH regulation. Here, we demonstrate that depleting PI(3,5)P2 by inhibiting the kinase PIKfyve causes lysosomal hyperacidification, primarily via an effect on ClC-7. We further show that PI(3,5)P2 directly inhibits ClC-7 transport and that this inhibition is eliminated in a disease-causing gain-of-function ClC-7 mutation. Together, these observations suggest an intimate role for ClC-7 in lysosomal pH regulation.
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Affiliation(s)
- Xavier Leray
- Membrane Transport Biophysics Section, National Institute of Neurological Disorders and Stroke
| | - Jacob K Hilton
- Membrane Transport Biophysics Section, National Institute of Neurological Disorders and Stroke
| | - Kamsi Nwangwu
- Membrane Transport Biophysics Section, National Institute of Neurological Disorders and Stroke
| | - Alissa Becerril
- Membrane Transport Biophysics Section, National Institute of Neurological Disorders and Stroke
| | - Vedrana Mikusevic
- Membrane Transport Biophysics Section, National Institute of Neurological Disorders and Stroke
| | - Gabriel Fitzgerald
- Membrane Transport Biophysics Section, National Institute of Neurological Disorders and Stroke
| | - Anowarul Amin
- Membrane Transport Biophysics Section, National Institute of Neurological Disorders and Stroke
| | - Mary R Weston
- Membrane Transport Biophysics Section, National Institute of Neurological Disorders and Stroke
| | - Joseph A Mindell
- Membrane Transport Biophysics Section, National Institute of Neurological Disorders and Stroke
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17
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The Role of the Lysosomal Cl−/H+ Antiporter ClC-7 in Osteopetrosis and Neurodegeneration. Cells 2022; 11:cells11030366. [PMID: 35159175 PMCID: PMC8833911 DOI: 10.3390/cells11030366] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 01/16/2022] [Accepted: 01/19/2022] [Indexed: 12/04/2022] Open
Abstract
CLC proteins comprise Cl− channels and anion/H+ antiporters involved in several fundamental physiological processes. ClC-7 is a lysosomal Cl−/H+ antiporter that together with its beta subunit Ostm1 has a critical role in the ionic homeostasis of lysosomes and of the osteoclasts’ resorption lacuna, although the specific underlying mechanism has so far remained elusive. Mutations in ClC-7 cause osteopetrosis, but also a form of lysosomal storage disease and neurodegeneration. Interestingly, both loss-of- and gain-of-function mutations of ClC-7 can be pathogenic, but the mechanistic implications of this finding are still unclear. This review will focus on the recent advances in our understanding of the biophysical properties of ClC-7 and of its role in human diseases with a focus on osteopetrosis and neurodegeneration.
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18
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Trojani MC, Santucci-Darmanin S, Breuil V, Carle GF, Pierrefite-Carle V. Autophagy and bone diseases. Joint Bone Spine 2021; 89:105301. [PMID: 34673234 DOI: 10.1016/j.jbspin.2021.105301] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/28/2021] [Indexed: 12/13/2022]
Abstract
Autophagy is a ubiquitous cellular process, allowing the removal and recycling of damaged proteins and organelles. At the basal level, this process plays a role in quality control, thus participating in cellular homeostasis. Autophagy can also be induced by various stresses, such as nutrient deprivation or hypoxia, to allow the cell to survive until conditions improve. In recent years, the role of this process has been widely studied in many pathologies such as neurodegenerative diseases or cancers. In bone tissue, various studies have shown that autophagy is involved in the survival, differentiation and activity of osteoblasts, osteocytes and osteoclasts. The evolution of this knowledge has led to the identification of new molecular pathophysiological mechanisms in bone pathologies. This review reports the current state of knowledge on the role of autophagy in 4 bone diseases: osteoporosis, which seems to be associated with a decrease in autophagy, osteopetrosis and Paget's disease where the course of the autophagic process is disturbed, and finally osteosarcoma where autophagy seems to play a protumoral role. A better understanding of the involvement of autophagy in these pathologies should eventually lead to the identification of new potential therapeutic targets.
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Affiliation(s)
- Marie-Charlotte Trojani
- UMR E-430 TIRO-MATOS CEA/DRF Institut Joliot, faculté de médecine de Nice, université Nice Côte d'Azur, 28, avenue de Valombrose, 06107 Nice cedex 2, France; Service de rhumatologie, CHU de Nice, Nice, France
| | - Sabine Santucci-Darmanin
- UMR E-430 TIRO-MATOS CEA/DRF Institut Joliot, faculté de médecine de Nice, université Nice Côte d'Azur, 28, avenue de Valombrose, 06107 Nice cedex 2, France
| | - Véronique Breuil
- UMR E-430 TIRO-MATOS CEA/DRF Institut Joliot, faculté de médecine de Nice, université Nice Côte d'Azur, 28, avenue de Valombrose, 06107 Nice cedex 2, France; Service de rhumatologie, CHU de Nice, Nice, France
| | - Georges F Carle
- UMR E-430 TIRO-MATOS CEA/DRF Institut Joliot, faculté de médecine de Nice, université Nice Côte d'Azur, 28, avenue de Valombrose, 06107 Nice cedex 2, France
| | - Valérie Pierrefite-Carle
- UMR E-430 TIRO-MATOS CEA/DRF Institut Joliot, faculté de médecine de Nice, université Nice Côte d'Azur, 28, avenue de Valombrose, 06107 Nice cedex 2, France; Inserm, Paris, France.
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19
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Duncan AR, Polovitskaya MM, Gaitán-Peñas H, Bertelli S, VanNoy GE, Grant PE, O’Donnell-Luria A, Valivullah Z, Lovgren AK, England EM, Agolini E, Madden JA, Schmitz-Abe K, Kritzer A, Hawley P, Novelli A, Alfieri P, Colafati GS, Wieczorek D, Platzer K, Luppe J, Koch-Hogrebe M, Abou Jamra R, Neira-Fresneda J, Lehman A, Boerkoel CF, Seath K, Clarke L, van Ierland Y, Argilli E, Sherr EH, Maiorana A, Diel T, Hempel M, Bierhals T, Estévez R, Jentsch TJ, Pusch M, Agrawal PB, Agrawal PB. Unique variants in CLCN3, encoding an endosomal anion/proton exchanger, underlie a spectrum of neurodevelopmental disorders. Am J Hum Genet 2021; 108:1450-1465. [PMID: 34186028 DOI: 10.1016/j.ajhg.2021.06.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 06/02/2021] [Indexed: 12/24/2022] Open
Abstract
The genetic causes of global developmental delay (GDD) and intellectual disability (ID) are diverse and include variants in numerous ion channels and transporters. Loss-of-function variants in all five endosomal/lysosomal members of the CLC family of Cl- channels and Cl-/H+ exchangers lead to pathology in mice, humans, or both. We have identified nine variants in CLCN3, the gene encoding CIC-3, in 11 individuals with GDD/ID and neurodevelopmental disorders of varying severity. In addition to a homozygous frameshift variant in two siblings, we identified eight different heterozygous de novo missense variants. All have GDD/ID, mood or behavioral disorders, and dysmorphic features; 9/11 have structural brain abnormalities; and 6/11 have seizures. The homozygous variants are predicted to cause loss of ClC-3 function, resulting in severe neurological disease similar to the phenotype observed in Clcn3-/- mice. Their MRIs show possible neurodegeneration with thin corpora callosa and decreased white matter volumes. Individuals with heterozygous variants had a range of neurodevelopmental anomalies including agenesis of the corpus callosum, pons hypoplasia, and increased gyral folding. To characterize the altered function of the exchanger, electrophysiological analyses were performed in Xenopus oocytes and mammalian cells. Two variants, p.Ile607Thr and p.Thr570Ile, had increased currents at negative cytoplasmic voltages and loss of inhibition by luminal acidic pH. In contrast, two other variants showed no significant difference in the current properties. Overall, our work establishes a role for CLCN3 in human neurodevelopment and shows that both homozygous loss of ClC-3 and heterozygous variants can lead to GDD/ID and neuroanatomical abnormalities.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Pankaj B Agrawal
- Division of Newborn Medicine, Department of Pediatrics, Boston Children's Hospital, Boston, MA 02115, USA; The Manton Center for Orphan Disease Research, Boston Children's Hospital, Boston, MA 02115, USA; Division of Genetics & Genomics, Department of Pediatrics, Boston Children's Hospital, MA 02115, USA.
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20
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Rössler U, Hennig AF, Stelzer N, Bose S, Kopp J, Søe K, Cyganek L, Zifarelli G, Ali S, von der Hagen M, Strässler ET, Hahn G, Pusch M, Stauber T, Izsvák Z, Gossen M, Stachelscheid H, Kornak U. Efficient generation of osteoclasts from human induced pluripotent stem cells and functional investigations of lethal CLCN7-related osteopetrosis. J Bone Miner Res 2021; 36:1621-1635. [PMID: 33905594 DOI: 10.1002/jbmr.4322] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 03/26/2021] [Accepted: 04/21/2021] [Indexed: 12/18/2022]
Abstract
Human induced pluripotent stem cells (hiPSCs) hold great potential for modeling human diseases and the development of innovative therapeutic approaches. Here, we report on a novel, simplified differentiation method for forming functional osteoclasts from hiPSCs. The three-step protocol starts with embryoid body formation, followed by hematopoietic specification, and finally osteoclast differentiation. We observed continuous production of monocyte-like cells over a period of up to 9 weeks, generating sufficient material for several osteoclast differentiations. The analysis of stage-specific gene and surface marker expression proved mesodermal priming, the presence of monocyte-like cells, and of terminally differentiated multinucleated osteoclasts, able to form resorption pits and trenches on bone and dentine in vitro. In comparison to peripheral blood mononuclear cell (PBMC)-derived osteoclasts hiPSC-derived osteoclasts were larger and contained a higher number of nuclei. Detailed functional studies on the resorption behavior of hiPSC-osteoclasts indicated a trend towards forming more trenches than pits and an increase in pseudoresorption. We used hiPSCs from an autosomal recessive osteopetrosis (ARO) patient (BIHi002-A, ARO hiPSCs) with compound heterozygous missense mutations p.(G292E) and p.(R403Q) in CLCN7, coding for the Cl- /H+ -exchanger ClC-7, for functional investigations. The patient's leading clinical feature was a brain malformation due to defective neuronal migration. Mutant ClC-7 displayed residual expression and retained lysosomal co-localization with OSTM1, the gene coding for the osteopetrosis-associated transmembrane protein 1, but only ClC-7 harboring the mutation p.(R403Q) gave strongly reduced ion currents. An increased autophagic flux in spite of unchanged lysosomal pH was evident in undifferentiated ARO hiPSCs. ARO hiPSC-derived osteoclasts showed an increased size compared to hiPSCs of healthy donors. They were not able to resorb bone, underlining a loss-of-function effect of the mutations. In summary, we developed a highly reproducible, straightforward hiPSC-osteoclast differentiation protocol. We demonstrated that osteoclasts differentiated from ARO hiPSCs can be used as a disease model for ARO and potentially also other osteoclast-related diseases. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Uta Rössler
- BIH Center for Regenerative Therapies (BCRT), Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Institute for Medical Genetics and Human Genetics, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Berlin Institute of Health (BIH), Berlin, Germany
| | - Anna Floriane Hennig
- BIH Center for Regenerative Therapies (BCRT), Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Institute for Medical Genetics and Human Genetics, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Freie Universität Berlin, Berlin, Germany.,Institute of Human Genetics, University Medical Center Göttingen, Göttingen, Germany
| | - Nina Stelzer
- BIH Center for Regenerative Therapies (BCRT), Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Institute for Medical Genetics and Human Genetics, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Shroddha Bose
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Johannes Kopp
- BIH Center for Regenerative Therapies (BCRT), Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Institute for Medical Genetics and Human Genetics, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Freie Universität Berlin, Berlin, Germany.,Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - Kent Søe
- Clinical Cell Biology, Department of Pathology, Odense University Hospital, Odense C, Denmark.,Department of Clinical Research, University of Southern Denmark, Odense M, Denmark.,Department of Molecular Medicine, University of Southern Denmark, Odense M, Denmark
| | - Lukas Cyganek
- Stem Cell Unit, Clinic for Cardiology and Pneumology, University Medical Center Göttingen, Göttingen, Germany.,German Center for Cardiovascular Research (DZHK), Partner Site Göttingen, Göttingen, Germany
| | | | - Salaheddine Ali
- BIH Center for Regenerative Therapies (BCRT), Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Institute for Medical Genetics and Human Genetics, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - Maja von der Hagen
- Abteilung Neuropädiatrie, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Elisabeth Tamara Strässler
- Department of Cardiology, Charité - Universitätsmedizin Berlin, Campus Benjamin Franklin, Berlin, Germany.,German Centre for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany
| | - Gabriele Hahn
- Institut und Poliklinik für Radiologische Diagnostik, Medizinische Fakultät Carl Gustav Carus Technische Universität Dresden, Dresden, Germany
| | | | - Tobias Stauber
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany.,Department of Human Medicine, and Institute for Molecular Medicine, MSH Medical School Hamburg, Hamburg, Germany
| | - Zsuzsanna Izsvák
- Max-Delbrück-Center for Molecular Medicine (MDC), Helmholtz Association, Berlin, Germany
| | - Manfred Gossen
- Berlin-Brandenburg Center for Regenerative Therapies, Charité Virchow Campus, Berlin, Germany.,Institute of Active Polymers, Helmholtz-Zentrum Hereon, Teltow, Germany
| | - Harald Stachelscheid
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Berlin Institute of Health (BIH), BIH Stem Cell Core Facility, Berlin, Germany
| | - Uwe Kornak
- BIH Center for Regenerative Therapies (BCRT), Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Institute for Medical Genetics and Human Genetics, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Institute of Human Genetics, University Medical Center Göttingen, Göttingen, Germany.,Max Planck Institute for Molecular Genetics, Berlin, Germany
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21
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Boscia F, Elkjaer ML, Illes Z, Kukley M. Altered Expression of Ion Channels in White Matter Lesions of Progressive Multiple Sclerosis: What Do We Know About Their Function? Front Cell Neurosci 2021; 15:685703. [PMID: 34276310 PMCID: PMC8282214 DOI: 10.3389/fncel.2021.685703] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Accepted: 05/23/2021] [Indexed: 12/19/2022] Open
Abstract
Despite significant advances in our understanding of the pathophysiology of multiple sclerosis (MS), knowledge about contribution of individual ion channels to axonal impairment and remyelination failure in progressive MS remains incomplete. Ion channel families play a fundamental role in maintaining white matter (WM) integrity and in regulating WM activities in axons, interstitial neurons, glia, and vascular cells. Recently, transcriptomic studies have considerably increased insight into the gene expression changes that occur in diverse WM lesions and the gene expression fingerprint of specific WM cells associated with secondary progressive MS. Here, we review the ion channel genes encoding K+, Ca2+, Na+, and Cl- channels; ryanodine receptors; TRP channels; and others that are significantly and uniquely dysregulated in active, chronic active, inactive, remyelinating WM lesions, and normal-appearing WM of secondary progressive MS brain, based on recently published bulk and single-nuclei RNA-sequencing datasets. We discuss the current state of knowledge about the corresponding ion channels and their implication in the MS brain or in experimental models of MS. This comprehensive review suggests that the intense upregulation of voltage-gated Na+ channel genes in WM lesions with ongoing tissue damage may reflect the imbalance of Na+ homeostasis that is observed in progressive MS brain, while the upregulation of a large number of voltage-gated K+ channel genes may be linked to a protective response to limit neuronal excitability. In addition, the altered chloride homeostasis, revealed by the significant downregulation of voltage-gated Cl- channels in MS lesions, may contribute to an altered inhibitory neurotransmission and increased excitability.
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Affiliation(s)
- Francesca Boscia
- Division of Pharmacology, Department of Neuroscience, Reproductive and Dentistry Sciences, School of Medicine, University of Naples "Federico II", Naples, Italy
| | - Maria Louise Elkjaer
- Neurology Research Unit, Department of Clinical Research, University of Southern Denmark, Odense, Denmark.,Department of Neurobiology Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Zsolt Illes
- Neurology Research Unit, Department of Clinical Research, University of Southern Denmark, Odense, Denmark.,Department of Neurobiology Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark.,Department of Neurology, Odense University Hospital, Odense, Denmark
| | - Maria Kukley
- Achucarro Basque Center for Neuroscience, Leioa, Spain.,Ikerbasque Basque Foundation for Science, Bilbao, Spain
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22
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Elson A, Stein M, Rabie G, Barnea-Zohar M, Winograd-Katz S, Reuven N, Shalev M, Sekeres J, Kanaan M, Tuckermann J, Geiger B. Sorting Nexin 10 as a Key Regulator of Membrane Trafficking in Bone-Resorbing Osteoclasts: Lessons Learned From Osteopetrosis. Front Cell Dev Biol 2021; 9:671210. [PMID: 34095139 PMCID: PMC8173195 DOI: 10.3389/fcell.2021.671210] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 04/23/2021] [Indexed: 12/30/2022] Open
Abstract
Bone homeostasis is a complex, multi-step process, which is based primarily on a tightly orchestrated interplay between bone formation and bone resorption that is executed by osteoblasts and osteoclasts (OCLs), respectively. The essential physiological balance between these cells is maintained and controlled at multiple levels, ranging from regulated gene expression to endocrine signals, yet the underlying cellular and molecular mechanisms are still poorly understood. One approach for deciphering the mechanisms that regulate bone homeostasis is the characterization of relevant pathological states in which this balance is disturbed. In this article we describe one such “error of nature,” namely the development of acute recessive osteopetrosis (ARO) in humans that is caused by mutations in sorting nexin 10 (SNX10) that affect OCL functioning. We hypothesize here that, by virtue of its specific roles in vesicular trafficking, SNX10 serves as a key selective regulator of the composition of diverse membrane compartments in OCLs, thereby affecting critical processes in the sequence of events that link the plasma membrane with formation of the ruffled border and with extracellular acidification. As a result, SNX10 determines multiple features of these cells either directly or, as in regulation of cell-cell fusion, indirectly. This hypothesis is further supported by the similarities between the cellular defects observed in OCLs form various models of ARO, induced by mutations in SNX10 and in other genes, which suggest that mutations in the known ARO-associated genes act by disrupting the same plasma membrane-to-ruffled border axis, albeit to different degrees. In this article, we describe the population genetics and spread of the original arginine-to-glutamine mutation at position 51 (R51Q) in SNX10 in the Palestinian community. We further review recent studies, conducted in animal and cellular model systems, that highlight the essential roles of SNX10 in critical membrane functions in OCLs, and discuss possible future research directions that are needed for challenging or substantiating our hypothesis.
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Affiliation(s)
- Ari Elson
- Department of Molecular Genetics, The Weizmann Institute of Science, Rehovot, Israel
| | - Merle Stein
- Institute of Comparative Molecular Endocrinology, University of Ulm, Ulm, Germany
| | - Grace Rabie
- Hereditary Research Laboratory and Department of Life Sciences, Bethlehem University, Bethlehem, Palestine
| | - Maayan Barnea-Zohar
- Department of Molecular Genetics, The Weizmann Institute of Science, Rehovot, Israel
| | | | - Nina Reuven
- Department of Molecular Genetics, The Weizmann Institute of Science, Rehovot, Israel
| | - Moran Shalev
- Department of Molecular Genetics, The Weizmann Institute of Science, Rehovot, Israel
| | - Juraj Sekeres
- Department of Immunology, The Weizmann Institute of Science, Rehovot, Israel
| | - Moien Kanaan
- Hereditary Research Laboratory and Department of Life Sciences, Bethlehem University, Bethlehem, Palestine
| | - Jan Tuckermann
- Institute of Comparative Molecular Endocrinology, University of Ulm, Ulm, Germany
| | - Benjamin Geiger
- Department of Immunology, The Weizmann Institute of Science, Rehovot, Israel
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23
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Norwood I, Szondi D, Ciocca M, Coudert A, Cohen-Solal M, Rucci N, Teti A, Maurizi A. Transcriptomic and bioinformatic analysis of Clcn7-dependent Autosomal Dominant Osteopetrosis type 2. Preclinical and clinical implications. Bone 2021; 144:115828. [PMID: 33359007 DOI: 10.1016/j.bone.2020.115828] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 11/26/2020] [Accepted: 12/17/2020] [Indexed: 12/30/2022]
Abstract
Autosomal Dominant Osteopetrosis type 2 (ADO2) is a rare genetic disease characterized by dense yet fragile bones. To date, the radiological approach remains the gold standard for ADO2 diagnosis. However, recent observations unveiled that ADO2 is a systemic disease affecting various organs beyond bone, including lung, kidney, muscle, and brain. Monitoring disease status and progression would greatly benefit from specific biomarkers shared by the affected organs. In this work, data derived from RNA deep sequencing (RNA dSeq) of bone, lung, kidney, muscle, brain, and osteoclasts isolated from wildtype (WT) and Clcn7G213R ADO2 mice were subjected to gene ontology and pathway analyses. Results showed the presence of alterations in gene ontology terms and pathways associated with bone metabolism and osteoclast biology, including JAK-STAT, cytokine-cytokine receptor, and hematopoietic cell lineage. Furthermore, in line with the multiorgan alterations caused by ADO2, the analysis of soft organs showed an enrichment of PPAR and neuroactive ligand-receptor interaction pathways known to be involved in the onset of tissue fibrosis and behavioral alterations, respectively. Finally, we observed the modulations of potential ADO2 biomarkers in organs and cells of ADO2 mice and in the peripheral blood mononuclear cells of patients, using conventional methods. Of note, some of these biomarkers could be possibly responsive to an effective experimental therapy based on a mutation-specific siRNA. Overall, the identified gene signature and the soluble forms of the encoded proteins could potentially represent reliable disease biomarkers that could improve the ADO2 diagnosis, the monitoring of both the skeletal and non-skeletal dysfunctions, and the assessment of the response to therapy.
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Affiliation(s)
- Iona Norwood
- Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy
| | - Denis Szondi
- Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy
| | - Michela Ciocca
- Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy
| | - Amélie Coudert
- Université de Paris, INSERM U 1132 Bioscar and Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Martine Cohen-Solal
- Université de Paris, INSERM U 1132 Bioscar and Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Nadia Rucci
- Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy
| | - Anna Teti
- Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy.
| | - Antonio Maurizi
- Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy
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24
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Bose S, He H, Stauber T. Neurodegeneration Upon Dysfunction of Endosomal/Lysosomal CLC Chloride Transporters. Front Cell Dev Biol 2021; 9:639231. [PMID: 33708769 PMCID: PMC7940362 DOI: 10.3389/fcell.2021.639231] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 02/03/2021] [Indexed: 12/15/2022] Open
Abstract
The regulation of luminal ion concentrations is critical for the function of, and transport between intracellular organelles. The importance of the acidic pH in the compartments of the endosomal-lysosomal pathway has been well-known for decades. Besides the V-ATPase, which pumps protons into their lumen, a variety of ion transporters and channels is involved in the regulation of the organelles' complex ion homeostasis. Amongst these are the intracellular members of the CLC family, ClC-3 through ClC-7. They localize to distinct but overlapping compartments of the endosomal-lysosomal pathway, partially with tissue-specific expression. Functioning as 2Cl−/H+ exchangers, they can support the vesicular acidification and accumulate luminal Cl−. Mutations in the encoding genes in patients and mouse models underlie severe phenotypes including kidney stones with CLCN5 and osteopetrosis or hypopigmentation with CLCN7. Dysfunction of those intracellular CLCs that are expressed in neurons lead to neuronal defects. Loss of endosomal ClC-3, which heteromerizes with ClC-4, results in neurodegeneration. Mutations in ClC-4 are associated with epileptic encephalopathy and intellectual disability. Mice lacking the late endosomal ClC-6 develop a lysosomal storage disease with reduced pain sensitivity. Human gene variants have been associated with epilepsy, and a gain-of-function mutation causes early-onset neurodegeneration. Dysfunction of the lysosomal ClC-7 leads to a lysosomal storage disease and neurodegeneration in mice and humans. Reduced luminal chloride, as well as altered calcium regulation, has been associated with lysosomal storage diseases in general. This review discusses the properties of endosomal and lysosomal Cl−/H+ exchange by CLCs and how various alterations of ion transport by CLCs impact organellar ion homeostasis and function in neurodegenerative disorders.
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Affiliation(s)
- Shroddha Bose
- Institute for Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Hailan He
- Institute for Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany.,Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China
| | - Tobias Stauber
- Institute for Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany.,Department of Human Medicine and Institute for Molecular Medicine, MSH Medical School Hamburg, Hamburg, Germany
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25
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He H, Cao X, Yin F, Wu T, Stauber T, Peng J. West Syndrome Caused By a Chloride/Proton Exchange-Uncoupling CLCN6 Mutation Related to Autophagic-Lysosomal Dysfunction. Mol Neurobiol 2021; 58:2990-2999. [PMID: 33590434 DOI: 10.1007/s12035-021-02291-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 01/12/2021] [Indexed: 12/25/2022]
Abstract
Vesicular chloride/proton exchangers of the CLC family are critically involved in the function of the endosomal-lysosomal pathway. Their dysfunction leads to severe disorders including intellectual disability and epilepsy for ClC-4, Dent's disease for ClC-5, and lysosomal storage disease and osteopetrosis for ClC-7. Here, we report a de novo variant p.Glu200Ala (p.E200A; c.599A>C) of the late endosomal ClC-6, encoded by CLCN6, in a patient with West syndrome (WS), severe developmental delay, autism, movement disorder, microcephaly, facial dysmorphism, and visual impairment. Mutation of this conserved glutamate uncouples chloride transport from proton antiport by ClC-6. This affects organellar ion homeostasis and was shown to be deleterious for other CLCs. In this study, we found that upon heterologous expression, the ClC-6 E200A variant caused autophagosome accumulation and impaired the clearance of autophagosomes by blocking autophagosome-lysosome fusion. Our study provides clinical and functional support for an association between CLCN6 variants and WS. Our findings also provide novel insights into the molecular mechanisms underlying the pathogenesis of WS, suggesting an involvement of autophagic-lysosomal dysfunction.
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Affiliation(s)
- Hailan He
- Department of Pediatrics, Xiangya Hospital, Central South University, Xiangya Road 87, Changsha, 410008, Hunan, China
| | - Xiaoshuang Cao
- Department of Pediatrics, Xiangya Hospital, Central South University, Xiangya Road 87, Changsha, 410008, Hunan, China
| | - Fei Yin
- Department of Pediatrics, Xiangya Hospital, Central South University, Xiangya Road 87, Changsha, 410008, Hunan, China.,Hunan Intellectual and Developmental Disabilities Research Center, Xiangya Road 87, Changsha, 410008, Hunan, China
| | - Tenghui Wu
- Department of Pediatrics, Xiangya Hospital, Central South University, Xiangya Road 87, Changsha, 410008, Hunan, China
| | - Tobias Stauber
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Thielallee 63, 14195, Berlin, Germany.,Institute for Molecular Medicine and Department of Human Medicine, MSH Medical School Hamburg, Am Kaiserkai 1, 20457, Hamburg, Germany
| | - Jing Peng
- Department of Pediatrics, Xiangya Hospital, Central South University, Xiangya Road 87, Changsha, 410008, Hunan, China. .,Hunan Intellectual and Developmental Disabilities Research Center, Xiangya Road 87, Changsha, 410008, Hunan, China.
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26
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Polovitskaya MM, Barbini C, Martinelli D, Harms FL, Cole FS, Calligari P, Bocchinfuso G, Stella L, Ciolfi A, Niceta M, Rizza T, Shinawi M, Sisco K, Johannsen J, Denecke J, Carrozzo R, Wegner DJ, Kutsche K, Tartaglia M, Jentsch TJ. A Recurrent Gain-of-Function Mutation in CLCN6, Encoding the ClC-6 Cl -/H +-Exchanger, Causes Early-Onset Neurodegeneration. Am J Hum Genet 2020; 107:1062-1077. [PMID: 33217309 PMCID: PMC7820737 DOI: 10.1016/j.ajhg.2020.11.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 11/02/2020] [Indexed: 12/16/2022] Open
Abstract
Dysfunction of the endolysosomal system is often associated with neurodegenerative disease because postmitotic neurons are particularly reliant on the elimination of intracellular aggregates. Adequate function of endosomes and lysosomes requires finely tuned luminal ion homeostasis and transmembrane ion fluxes. Endolysosomal CLC Cl-/H+ exchangers function as electric shunts for proton pumping and in luminal Cl- accumulation. We now report three unrelated children with severe neurodegenerative disease, who carry the same de novo c.1658A>G (p.Tyr553Cys) mutation in CLCN6, encoding the late endosomal Cl-/H+-exchanger ClC-6. Whereas Clcn6-/- mice have only mild neuronal lysosomal storage abnormalities, the affected individuals displayed severe developmental delay with pronounced generalized hypotonia, respiratory insufficiency, and variable neurodegeneration and diffusion restriction in cerebral peduncles, midbrain, and/or brainstem in MRI scans. The p.Tyr553Cys amino acid substitution strongly slowed ClC-6 gating and increased current amplitudes, particularly at the acidic pH of late endosomes. Transfection of ClC-6Tyr553Cys, but not ClC-6WT, generated giant LAMP1-positive vacuoles that were poorly acidified. Their generation strictly required ClC-6 ion transport, as shown by transport-deficient double mutants, and depended on Cl-/H+ exchange, as revealed by combination with the uncoupling p.Glu200Ala substitution. Transfection of either ClC-6Tyr553Cys/Glu200Ala or ClC-6Glu200Ala generated slightly enlarged vesicles, suggesting that p.Glu200Ala, previously associated with infantile spasms and microcephaly, is also pathogenic. Bafilomycin treatment abrogated vacuole generation, indicating that H+-driven Cl- accumulation osmotically drives vesicle enlargement. Our work establishes mutations in CLCN6 associated with neurological diseases, whose spectrum of clinical features depends on the differential impact of the allele on ClC-6 function.
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Affiliation(s)
- Maya M Polovitskaya
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), 13125 Berlin, Germany; Max-Delbrück-Centrum für Molekulare Medizin (MDC), 13125 Berlin, Germany
| | - Carlo Barbini
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), 13125 Berlin, Germany; Max-Delbrück-Centrum für Molekulare Medizin (MDC), 13125 Berlin, Germany
| | - Diego Martinelli
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, IRCCS, 00146 Rome, Italy
| | - Frederike L Harms
- Institute for Human Genetics, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - F Sessions Cole
- Division of Newborn Medicine, Edward Mallinckrodt Department of Pediatrics, Washington University School of Medicine, and St. Louis Children's Hospital, St. Louis, MO 63110, USA
| | - Paolo Calligari
- Department of Chemical Science and Technologies, University "Tor Vergata," 00133 Rome, Italy
| | - Gianfranco Bocchinfuso
- Department of Chemical Science and Technologies, University "Tor Vergata," 00133 Rome, Italy
| | - Lorenzo Stella
- Department of Chemical Science and Technologies, University "Tor Vergata," 00133 Rome, Italy
| | - Andrea Ciolfi
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, IRCCS, 00146 Rome, Italy
| | - Marcello Niceta
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, IRCCS, 00146 Rome, Italy
| | - Teresa Rizza
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, IRCCS, 00146 Rome, Italy
| | - Marwan Shinawi
- Division of Genetics and Genomic Medicine, Edward Mallinckrodt Department of Pediatrics, Washington University School of Medicine, and St. Louis Children's Hospital, St. Louis, MO 63110, USA
| | - Kathleen Sisco
- Division of Genetics and Genomic Medicine, Edward Mallinckrodt Department of Pediatrics, Washington University School of Medicine, and St. Louis Children's Hospital, St. Louis, MO 63110, USA
| | - Jessika Johannsen
- Children's Hospital, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Jonas Denecke
- Children's Hospital, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Rosalba Carrozzo
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, IRCCS, 00146 Rome, Italy
| | - Daniel J Wegner
- Division of Newborn Medicine, Edward Mallinckrodt Department of Pediatrics, Washington University School of Medicine, and St. Louis Children's Hospital, St. Louis, MO 63110, USA
| | - Kerstin Kutsche
- Institute for Human Genetics, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Marco Tartaglia
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, IRCCS, 00146 Rome, Italy.
| | - Thomas J Jentsch
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), 13125 Berlin, Germany; Max-Delbrück-Centrum für Molekulare Medizin (MDC), 13125 Berlin, Germany; NeuroCure Cluster of Excellence, Charité Universitätsmedizin, 10117 Berlin, Germany.
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27
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Chloride channel 7 protects from redox status impairment-induced renal tubular epithelial cell apoptosis by activating autophagy. Life Sci 2020; 261:118484. [PMID: 32976885 DOI: 10.1016/j.lfs.2020.118484] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 09/08/2020] [Accepted: 09/18/2020] [Indexed: 02/07/2023]
Abstract
AIM Chloride channel 7 (CLC-7), broadly expressed in kidney tissues, affects the lysosome degradation pathway. And redox status impairment contributes to cell apoptosis and activates autophagy flux. This study mainly investigates the role and molecular mechanism of CLC-7 in redox status impairment-induced autophagic flux and apoptosis. MAIN METHODS When NRK52E cells, rat renal tubular epithelial cells, were exposed to H2O2 treatment, apoptosis, autophagy flux, and CLC-7 expression were detected. Further investigation was done to observe the change of apoptosis and autophagy flux in renal cells under overexpression or knocking down of CLC-7. The lysosomes acidity, lysosome enzyme Cathepsin D activity and phosphorylation of Ampk/mTOR were also examined when CLC-7 was overexpressed or knocked down. KEY FINDINGS Redox status impairment induced apoptosis and autophagy flux in NRK52E cells and upregulated CLC-7. Overexpression of CLC-7 increased lysosome acidity and Cathepsin D activity. In cells with CLC-7 overexpression, we observed a significant increase of autophagy flux and decline of apoptosis, as well as an apparent increase of p-Ampk and decrease of p-mTOR. On the contrary, cells with knocking down CLC-7 led to opposite results. SIGNIFICANCES CLC-7 is essential to maintain and enhance acidity and enzyme activity in lysosome. Through activating autophagy flux, it exerts survival against renal tubular epithelial cell apoptosis induced by redox status impairment. Its function to modulate Ampk/mTOR pathway is the possible reason why CLC-7 can trigger autophagy flux.
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28
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Stein M, Barnea-Zohar M, Shalev M, Arman E, Brenner O, Winograd-Katz S, Gerstung J, Thalji F, Kanaan M, Elinav H, Stepensky P, Geiger B, Tuckermann J, Elson A. Massive osteopetrosis caused by non-functional osteoclasts in R51Q SNX10 mutant mice. Bone 2020; 136:115360. [PMID: 32278070 DOI: 10.1016/j.bone.2020.115360] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 04/06/2020] [Accepted: 04/06/2020] [Indexed: 11/18/2022]
Abstract
The R51Q mutation in sorting nexin 10 (SNX10) was shown to cause a lethal genetic disease in humans, namely autosomal recessive osteopetrosis (ARO). We describe here the first R51Q SNX10 knock-in mouse model and show that mice homozygous for this mutation exhibit massive, early-onset, and widespread osteopetrosis. The mutant mice exhibit multiple additional characteristics of the corresponding human disease, including stunted growth, failure to thrive, missing or impacted teeth, occasional osteomyelitis, and a significantly-reduced lifespan. Osteopetrosis in this model is the result of osteoclast inactivity that, in turn, is caused by absence of ruffled borders in the mutant osteoclasts and by their inability to secrete protons. These results confirm that the R51Q mutation in SNX10 is a causative factor in ARO and provide a model system for studying this rare disease.
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Affiliation(s)
- Merle Stein
- Institute of Comparative Molecular Endocrinology, University of Ulm, 89081 Ulm, Germany
| | - Maayan Barnea-Zohar
- Department of Molecular Genetics, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Moran Shalev
- Department of Molecular Genetics, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Esther Arman
- Department of Molecular Genetics, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Ori Brenner
- Department of Veterinary Resources, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Sabina Winograd-Katz
- Department of Molecular Cell Biology, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Jennifer Gerstung
- Institute of Comparative Molecular Endocrinology, University of Ulm, 89081 Ulm, Germany
| | - Fadi Thalji
- Istishari Arab Hospital, Ramallah, Palestine
| | - Moien Kanaan
- Hereditary Research Laboratory and Department of Life Sciences, Bethlehem University, Bethlehem, Palestine
| | - Hila Elinav
- Department of Clinical Microbiology and Infectious Diseases, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Polina Stepensky
- Department of Bone Marrow Transplantation and Cancer Immunotherapy, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Benjamin Geiger
- Department of Molecular Cell Biology, The Weizmann Institute of Science, Rehovot 76100, Israel.
| | - Jan Tuckermann
- Institute of Comparative Molecular Endocrinology, University of Ulm, 89081 Ulm, Germany.
| | - Ari Elson
- Department of Molecular Genetics, The Weizmann Institute of Science, Rehovot 76100, Israel.
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29
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Astaburuaga R, Quintanar Haro OD, Stauber T, Relógio A. A Mathematical Model of Lysosomal Ion Homeostasis Points to Differential Effects of Cl - Transport in Ca 2+ Dynamics. Cells 2019; 8:E1263. [PMID: 31623161 PMCID: PMC6848924 DOI: 10.3390/cells8101263] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2019] [Revised: 10/11/2019] [Accepted: 10/13/2019] [Indexed: 12/20/2022] Open
Abstract
The establishment and maintenance of ion gradients between the interior of lysosomes and the cytosol are crucial for numerous cellular and organismal functions. Numerous ion transport proteins ensure the required variation in luminal concentrations of the different ions along the endocytic pathway to fit the needs of the organelles. Failures in keeping proper ion homeostasis have pathological consequences. Accordingly, several human diseases are caused by the dysfunction of ion transporters. These include osteopetrosis, caused by the dysfunction of Cl-/H+ exchange by the lysosomal transporter ClC-7. To better understand how chloride transport affects lysosomal ion homeostasis and how its disruption impinges on lysosomal function, we developed a mathematical model of lysosomal ion homeostasis including Ca2+ dynamics. The model recapitulates known biophysical properties of ClC-7 and enables the investigation of its differential activation kinetics on lysosomal ion homeostasis. We show that normal functioning of ClC-7 supports the acidification process, is associated with increased luminal concentrations of sodium, potassium, and chloride, and leads to a higher Ca2+ uptake and release. Our model highlights the role of ClC-7 in lysosomal acidification and shows the existence of differential Ca2+ dynamics upon perturbations of Cl-/H+ exchange and its activation kinetics, with possible pathological consequences.
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Affiliation(s)
- Rosario Astaburuaga
- Institute for Theoretical Biology (ITB), Charité-Universitätsmedizin Berlin, Corporate Member of the Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 10115 Berlin, Germany.
- Medical Department of Hematology, Oncology and Tumor Immunology, Molekulares Krebsforschungzentrum (MKFZ), Charité-Universitätsmedizin Berlin, Corporate Member of the Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 13353 Berlin, Germany.
| | - Orlando Daniel Quintanar Haro
- Institute for Theoretical Biology (ITB), Charité-Universitätsmedizin Berlin, Corporate Member of the Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 10115 Berlin, Germany.
- Freie Universität Berlin, Institute of Chemistry and Biochemistry, 14195 Berlin, Germany.
| | - Tobias Stauber
- Freie Universität Berlin, Institute of Chemistry and Biochemistry, 14195 Berlin, Germany.
- Department of Human Medicine, Medical School Hamburg, 20457 Hamburg, Germany.
| | - Angela Relógio
- Institute for Theoretical Biology (ITB), Charité-Universitätsmedizin Berlin, Corporate Member of the Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 10115 Berlin, Germany.
- Medical Department of Hematology, Oncology and Tumor Immunology, Molekulares Krebsforschungzentrum (MKFZ), Charité-Universitätsmedizin Berlin, Corporate Member of the Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 13353 Berlin, Germany.
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30
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Maurizi A, Capulli M, Curle A, Patel R, Ucci A, Côrtes JA, Oxford H, Lamandé SR, Bateman JF, Rucci N, Teti A. Extra-skeletal manifestations in mice affected by Clcn7-dependent autosomal dominant osteopetrosis type 2 clinical and therapeutic implications. Bone Res 2019; 7:17. [PMID: 31231577 PMCID: PMC6559989 DOI: 10.1038/s41413-019-0055-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 05/10/2019] [Indexed: 12/16/2022] Open
Abstract
Autosomal dominant osteopetrosis type 2 (ADO2) is a high-density brittle bone disease characterized by bone pain, multiple fractures and skeletal-related events, including nerve compression syndrome and hematological failure. We demonstrated that in mice carrying the heterozygous Clcn7G213R mutation, whose human mutant homolog CLCN7G215R affects patients, the clinical impacts of ADO2 extend beyond the skeleton, affecting several other organs. The hallmark of the extra-skeletal alterations is a consistent perivascular fibrosis, associated with high numbers of macrophages and lymphoid infiltrates. Fragmented clinical information in a small cohort of patients confirms extra-skeletal alterations consistent with a systemic disease, in line with the observation that the CLCN7 gene is expressed in many organs. ADO2 mice also show anxiety and depression and their brains exhibit not only perivascular fibrosis but also β-amyloid accumulation and astrogliosis, suggesting the involvement of the nervous system in the pathogenesis of the ADO2 extra-skeletal alterations. Extra-skeletal organs share a similar cellular pathology, confirmed also in vitro in bone marrow mononuclear cells and osteoclasts, characterized by an impairment of the exit pathway of the Clcn7 protein product, ClC7, through the Golgi, with consequent reduced ClC7 expression in late endosomes and lysosomes, associated with high vesicular pH and accumulation of autophagosome markers. Finally, an experimental siRNA therapy, previously proven to counteract the bone phenotype, also improves the extra-skeletal alterations. These results could have important clinical implications, supporting the notion that a systematic evaluation of ADO2 patients for extra-skeletal symptoms could help improve their diagnosis, clinical management, and therapeutic options.
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Affiliation(s)
- Antonio Maurizi
- 1Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy
| | - Mattia Capulli
- 1Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy
| | - Annabel Curle
- 1Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy
| | - Rajvi Patel
- 1Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy
| | - Argia Ucci
- 1Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy
| | - Juliana Alves Côrtes
- 1Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy
| | - Harriet Oxford
- 1Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy
| | - Shireen R Lamandé
- 2Murdoch Children's Research Institute and University of Melbourne, Melbourne, Australia
| | - John F Bateman
- 2Murdoch Children's Research Institute and University of Melbourne, Melbourne, Australia
| | - Nadia Rucci
- 1Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy
| | - Anna Teti
- 1Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy
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Starvation-induced autophagy is up-regulated via ROS-mediated ClC-3 chloride channel activation in the nasopharyngeal carcinoma cell line CNE-2Z. Biochem J 2019; 476:1323-1333. [DOI: 10.1042/bcj20180979] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Revised: 04/13/2019] [Accepted: 04/16/2019] [Indexed: 01/15/2023]
Abstract
Abstract
Nutrient deficiency develops frequently in nasopharyngeal carcinoma cell (CNE-2Z) due to the characteristics of aggregation and uncontrolled proliferation. Therefore, starvation can induce autophagy in these cells. Chloride channel 3 (ClC-3), a member of the chloride channel family, is involved in various biological processes. However, whether ClC-3 plays an important role in starvation-induced autophagy is unclear. In this study, Earle's balanced salt solution (EBSS) was used to induce autophagy in CNE-2Z cells. We found that autophagy and the chloride current induced by EBSS were inhibited by chloride channel blockers. ClC-3 knockdown inhibited the degradation of LC3-II and P62. Furthermore, when reactive oxygen species (ROS) generation was suppressed by antioxidant N-acetyl-l-cysteine (L-NAC) pretreatment, EBSS-induced autophagy was inhibited, and the chloride current was unable to be activated. Nevertheless, ClC-3 knockdown had little effect on ROS levels, indicating that ROS acted upstream of ClC-3 and that both ROS and ClC-3 participated in EBSS-induced autophagy regulation in CNE-2Z.
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Jentsch TJ, Pusch M. CLC Chloride Channels and Transporters: Structure, Function, Physiology, and Disease. Physiol Rev 2018; 98:1493-1590. [DOI: 10.1152/physrev.00047.2017] [Citation(s) in RCA: 214] [Impact Index Per Article: 35.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
CLC anion transporters are found in all phyla and form a gene family of eight members in mammals. Two CLC proteins, each of which completely contains an ion translocation parthway, assemble to homo- or heteromeric dimers that sometimes require accessory β-subunits for function. CLC proteins come in two flavors: anion channels and anion/proton exchangers. Structures of these two CLC protein classes are surprisingly similar. Extensive structure-function analysis identified residues involved in ion permeation, anion-proton coupling and gating and led to attractive biophysical models. In mammals, ClC-1, -2, -Ka/-Kb are plasma membrane Cl−channels, whereas ClC-3 through ClC-7 are 2Cl−/H+-exchangers in endolysosomal membranes. Biological roles of CLCs were mostly studied in mammals, but also in plants and model organisms like yeast and Caenorhabditis elegans. CLC Cl−channels have roles in the control of electrical excitability, extra- and intracellular ion homeostasis, and transepithelial transport, whereas anion/proton exchangers influence vesicular ion composition and impinge on endocytosis and lysosomal function. The surprisingly diverse roles of CLCs are highlighted by human and mouse disorders elicited by mutations in their genes. These pathologies include neurodegeneration, leukodystrophy, mental retardation, deafness, blindness, myotonia, hyperaldosteronism, renal salt loss, proteinuria, kidney stones, male infertility, and osteopetrosis. In this review, emphasis is laid on biophysical structure-function analysis and on the cell biological and organismal roles of mammalian CLCs and their role in disease.
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Affiliation(s)
- Thomas J. Jentsch
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin (MDC), Berlin, Germany; and Istituto di Biofisica, Consiglio Nazionale delle Ricerche, Genova, Italy
| | - Michael Pusch
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin (MDC), Berlin, Germany; and Istituto di Biofisica, Consiglio Nazionale delle Ricerche, Genova, Italy
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Kondratskyi A, Kondratska K, Skryma R, Klionsky DJ, Prevarskaya N. Ion channels in the regulation of autophagy. Autophagy 2017; 14:3-21. [PMID: 28980859 PMCID: PMC5846505 DOI: 10.1080/15548627.2017.1384887] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Revised: 09/07/2017] [Accepted: 09/21/2017] [Indexed: 12/18/2022] Open
Abstract
Autophagy is a cellular process in which the cell degrades and recycles its own constituents. Given the crucial role of autophagy in physiology, deregulation of autophagic machinery is associated with various diseases. Hence, a thorough understanding of autophagy regulatory mechanisms is crucially important for the elaboration of efficient treatments for different diseases. Recently, ion channels, mediating ion fluxes across cellular membranes, have emerged as important regulators of both basal and induced autophagy. However, the mechanisms by which specific ion channels regulate autophagy are still poorly understood, thus underscoring the need for further research in this field. Here we discuss the involvement of major types of ion channels in autophagy regulation.
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Affiliation(s)
- Artem Kondratskyi
- Inserm, U-1003, Laboratory of Excellence, Ion Channels Science and Therapeutics, University of Lille 1, Villeneuve d'Ascq, France
| | - Kateryna Kondratska
- Inserm, U-1003, Laboratory of Excellence, Ion Channels Science and Therapeutics, University of Lille 1, Villeneuve d'Ascq, France
| | - Roman Skryma
- Inserm, U-1003, Laboratory of Excellence, Ion Channels Science and Therapeutics, University of Lille 1, Villeneuve d'Ascq, France
| | - Daniel J. Klionsky
- Life Sciences Institute, and Department of Molecular, Cellular and Developmental Biology; University of Michigan, Ann Arbor, MI, USA
| | - Natalia Prevarskaya
- Inserm, U-1003, Laboratory of Excellence, Ion Channels Science and Therapeutics, University of Lille 1, Villeneuve d'Ascq, France
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Chakraborty K, Leung K, Krishnan Y. High lumenal chloride in the lysosome is critical for lysosome function. eLife 2017; 6. [PMID: 28742019 PMCID: PMC5526669 DOI: 10.7554/elife.28862] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2017] [Accepted: 06/23/2017] [Indexed: 12/31/2022] Open
Abstract
Lysosomes are organelles responsible for the breakdown and recycling of cellular machinery. Dysfunctional lysosomes give rise to lysosomal storage disorders as well as common neurodegenerative diseases. Here, we use a DNA-based, fluorescent chloride reporter to measure lysosomal chloride in Caenorhabditis elegans as well as murine and human cell culture models of lysosomal diseases. We find that the lysosome is highly enriched in chloride, and that chloride reduction correlates directly with a loss in the degradative function of the lysosome. In nematodes and mammalian cell culture models of diverse lysosomal disorders, where previously only lysosomal pH dysregulation has been described, massive reduction of lumenal chloride is observed that is ~103 fold greater than the accompanying pH change. Reducing chloride within the lysosome impacts Ca2+ release from the lysosome and impedes the activity of specific lysosomal enzymes indicating a broader role for chloride in lysosomal function. DOI:http://dx.doi.org/10.7554/eLife.28862.001 In cells, worn out proteins and other unnecessary materials are sent to small compartments called lysosomes to be broken down and recycled. Lysosomes contain many different proteins including some that break down waste material into recyclable fragments and others that transport the fragments out of the lysosome. If any of these proteins do not work, waste products build up and cause disease. There are around 70 such lysosomal storage diseases, each arising from a different lysosomal protein not working correctly. A recently developed “nanodevice” called Clensor can measure the levels of chloride ions inside cells. Clensor is constructed from DNA, and its fluorescence changes when it detects chloride ions. Although chloride ions have many biological roles, chloride ion levels had not been measured inside a living organism. Now, Chakraborty et al. – including some of the researchers who developed Clensor – have used this nanodevice to examine chloride ion levels in the lysosomes of the roundworm Caenorhabditis elegans. This revealed that the lysosomes contain high levels of chloride ions. Furthermore, reducing the amount of chloride in the lysosomes made them worse at breaking down waste. Do lysosomes affected by lysosome storage diseases also contain low levels of chloride ions? To find out, Chakraborty et al. used Clensor to study C. elegans worms and mouse and human cells whose lysosomes accumulate waste products. In all these cases, the levels of chloride in the diseased lysosomes were much lower than normal. This had a number of effects on how the lysosomes worked, such as reducing the activity of key lysosomal proteins. Chakraborty et al. also found that Clensor can be used to distinguish between different lysosomal storage diseases. This means that in the future, Clensor (or similar methods that directly measure chloride ion levels in lysosomes) may be useful not just for research purposes. They may also be valuable for diagnosing lysosomal storage diseases early in infancy that, if left undiagnosed, are fatal. DOI:http://dx.doi.org/10.7554/eLife.28862.002
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Affiliation(s)
- Kasturi Chakraborty
- Department of Chemistry, University of Chicago, Chicago, United States.,Grossman Institute of Neuroscience, Quantitative Biology and Human Behavior, University of Chicago, Chicago, United States
| | - KaHo Leung
- Department of Chemistry, University of Chicago, Chicago, United States.,Grossman Institute of Neuroscience, Quantitative Biology and Human Behavior, University of Chicago, Chicago, United States
| | - Yamuna Krishnan
- Department of Chemistry, University of Chicago, Chicago, United States.,Grossman Institute of Neuroscience, Quantitative Biology and Human Behavior, University of Chicago, Chicago, United States
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35
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Poroca DR, Pelis RM, Chappe VM. ClC Channels and Transporters: Structure, Physiological Functions, and Implications in Human Chloride Channelopathies. Front Pharmacol 2017; 8:151. [PMID: 28386229 PMCID: PMC5362633 DOI: 10.3389/fphar.2017.00151] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 03/09/2017] [Indexed: 02/04/2023] Open
Abstract
The discovery of ClC proteins at the beginning of the 1990s was important for the development of the Cl- transport research field. ClCs form a large family of proteins that mediate voltage-dependent transport of Cl- ions across cell membranes. They are expressed in both plasma and intracellular membranes of cells from almost all living organisms. ClC proteins form transmembrane dimers, in which each monomer displays independent ion conductance. Eukaryotic members also possess a large cytoplasmic domain containing two CBS domains, which are involved in transport modulation. ClC proteins function as either Cl- channels or Cl-/H+ exchangers, although all ClC proteins share the same basic architecture. ClC channels have two gating mechanisms: a relatively well-studied fast gating mechanism, and a slow gating mechanism, which is poorly defined. ClCs are involved in a wide range of physiological processes, including regulation of resting membrane potential in skeletal muscle, facilitation of transepithelial Cl- reabsorption in kidneys, and control of pH and Cl- concentration in intracellular compartments through coupled Cl-/H+ exchange mechanisms. Several inherited diseases result from C1C gene mutations, including myotonia congenita, Bartter's syndrome (types 3 and 4), Dent's disease, osteopetrosis, retinal degeneration, and lysosomal storage diseases. This review summarizes general features, known or suspected, of ClC structure, gating and physiological functions. We also discuss biophysical properties of mammalian ClCs that are directly involved in the pathophysiology of several human inherited disorders, or that induce interesting phenotypes in animal models.
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Affiliation(s)
- Diogo R Poroca
- Department of Physiology and Biophysics, Dalhousie University, Halifax NS, Canada
| | - Ryan M Pelis
- Department of Pharmacology, Dalhousie University, Halifax NS, Canada
| | - Valérie M Chappe
- Department of Physiology and Biophysics, Dalhousie University, Halifax NS, Canada
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36
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Abstract
Lysosomes, the major membrane-bound degradative organelles, have a multitude of functions in eukaryotic cells. Lysosomes are the terminal compartments in the endocytic pathway, though they display highly dynamic behaviors, fusing with each other and with late endosomes in the endocytic pathway, and with the plasma membrane during regulated exocytosis and for wound repair. After fusing with late endosomes, lysosomes are reformed from the resulting hybrid organelles through a process that involves budding of a nascent lysosome, extension of the nascent lysosome from the hybrid organelle, while remaining connected by a membrane bridge, and scission of the membrane bridge to release the newly formed lysosome. The newly formed lysosomes undergo cycles of homotypic fusion and fission reactions to form mature lysosomes. In this study, we used a forward genetic screen in Caenorhabditis elegans to identify six regulators of lysosome biology. We show that these proteins function in different steps of lysosome biology, regulating lysosome formation, lysosome fusion, and lysosome degradation.
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37
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Piret SE, Gorvin CM, Trinh A, Taylor J, Lise S, Taylor JC, Ebeling PR, Thakker RV. Autosomal dominant osteopetrosis associated with renal tubular acidosis is due to a CLCN7 mutation. Am J Med Genet A 2016; 170:2988-2992. [PMID: 27540713 PMCID: PMC5132132 DOI: 10.1002/ajmg.a.37755] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Accepted: 04/21/2016] [Indexed: 12/16/2022]
Abstract
The aim of this study was to identify the causative mutation in a family with an unusual presentation of autosomal dominant osteopetrosis (OPT), proximal renal tubular acidosis (RTA), renal stones, epilepsy, and blindness, a combination of features not previously reported. We undertook exome sequencing of one affected and one unaffected family member, followed by targeted analysis of known candidate genes to identify the causative mutation. This identified a missense mutation (c.643G>A; p.Gly215Arg) in the gene encoding the chloride/proton antiporter 7 (gene CLCN7, protein CLC‐7), which was confirmed by amplification refractory mutation system (ARMS)‐PCR, and to be present in the three available patients. CLC‐7 mutations are known to cause autosomal dominant OPT type 2, also called Albers–Schonberg disease, which is characterized by osteosclerosis, predominantly of the spine, pelvis and skull base, resulting in bone fragility and fractures. Albers–Schonberg disease is not reported to be associated with RTA, but autosomal recessive OPT type 3 (OPTB3) with RTA is associated with carbonic anhydrase type 2 (CA2) mutations. No mutations were detected in CA2 or any other genes known to cause proximal RTA. Neither CLCN7 nor CA2 mutations have previously been reported to be associated with renal stones or epilepsy. Thus, we identified a CLCN7 mutation in a family with autosomal dominant osteopetrosis, RTA, renal stones, epilepsy, and blindness. © 2016 The Authors. American Journal of Medical Genetics Part A Published by Wiley Periodicals, Inc.
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Affiliation(s)
- Sian E Piret
- Academic Endocrine Unit, Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, University of Oxford, Oxford, United Kingdom
| | - Caroline M Gorvin
- Academic Endocrine Unit, Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, University of Oxford, Oxford, United Kingdom
| | - Anne Trinh
- Faculty of Medicine, Nursing and Health Sciences, Department of Medicine, School of Clinical Sciences, Monash Medical Centre, Monash University, Clayton, Victoria, Australia
| | - John Taylor
- Oxford Medical Genetics Laboratories, Churchill Hospital, Oxford University Hospitals NHS Trust, Oxford, United Kingdom
| | - Stefano Lise
- Wellcome Trust Centre for Human Genetics, Oxford, United Kingdom
- Oxford NIHR Comprehensive Biomedical Research Centre, Oxford, United Kingdom
| | - Jenny C Taylor
- Wellcome Trust Centre for Human Genetics, Oxford, United Kingdom
- Oxford NIHR Comprehensive Biomedical Research Centre, Oxford, United Kingdom
| | - Peter R Ebeling
- Faculty of Medicine, Nursing and Health Sciences, Department of Medicine, School of Clinical Sciences, Monash Medical Centre, Monash University, Clayton, Victoria, Australia
| | - Rajesh V Thakker
- Academic Endocrine Unit, Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, University of Oxford, Oxford, United Kingdom.
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38
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Barrallo-Gimeno A, Gradogna A, Zanardi I, Pusch M, Estévez R. Regulatory-auxiliary subunits of CLC chloride channel-transport proteins. J Physiol 2016; 593:4111-27. [PMID: 25762128 DOI: 10.1113/jp270057] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Accepted: 02/15/2015] [Indexed: 02/06/2023] Open
Abstract
The CLC family of chloride channels and transporters is composed by nine members, but only three of them, ClC-Ka/b, ClC-7 and ClC-2, have been found so far associated with auxiliary subunits. These CLC regulatory subunits are small proteins that present few common characteristics among them, both structurally and functionally, and their effects on the corresponding CLC protein are different. Barttin, a protein with two transmembrane domains, is essential for the membrane localization of ClC-K proteins and their activity in the kidney and inner ear. Ostm1 is a protein with a single transmembrane domain and a highly glycosylated N-terminus. Unlike the other two CLC auxiliary subunits, Ostm1 shows a reciprocal relationship with ClC-7 for their stability. The subcellular localization of Ostm1 depends on ClC-7 and not the other way around. ClC-2 is active on its own, but GlialCAM, a transmembrane cell adhesion molecule with two extracellular immunoglobulin (Ig)-like domains, regulates its subcellular localization and activity in glial cells. The common theme for these three proteins is their requirement for a proper homeostasis, since their malfunction leads to distinct diseases. We will review here their properties and their role in normal chloride physiology and the pathological consequences of their improper function.
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Affiliation(s)
- Alejandro Barrallo-Gimeno
- Sección de Fisiología, Departamento de Ciencias Fisiológicas II, University of Barcelona, Barcelona, Spain.,U-750, Centro de investigación en red de enfermedades raras (CIBERER), ISCIII, Barcelona, Spain
| | | | - Ilaria Zanardi
- Istituto di Biofisica, Consiglio Nazionale delle Ricerche, Genoa, Italy
| | - Michael Pusch
- Istituto di Biofisica, Consiglio Nazionale delle Ricerche, Genoa, Italy
| | - Raúl Estévez
- Sección de Fisiología, Departamento de Ciencias Fisiológicas II, University of Barcelona, Barcelona, Spain.,U-750, Centro de investigación en red de enfermedades raras (CIBERER), ISCIII, Barcelona, Spain
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Pierrefite-Carle V, Santucci-Darmanin S, Breuil V, Camuzard O, Carle GF. Autophagy in bone: Self-eating to stay in balance. Ageing Res Rev 2015; 24:206-17. [PMID: 26318060 DOI: 10.1016/j.arr.2015.08.004] [Citation(s) in RCA: 101] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 08/18/2015] [Accepted: 08/20/2015] [Indexed: 12/14/2022]
Abstract
Autophagy, a major catabolic pathway responsible of the elimination of damaged proteins and organelles, is now recognized as an anti-aging process. In addition to its basal role in cell homeostasis, autophagy is also a stress-responsive mechanism for survival purposes. Here, we review recent literature to highlight the autophagy role in the different bone cell types, i.e., osteoblasts, osteoclasts and osteocytes. We also discuss the effects of autophagy modulators in bone physiology and of bone anabolic compounds in autophagy. Finally, we analyzed studies regarding bone cell autophagy-deficient mouse models to obtain a more general view on how autophagy modulates bone physiology and pathophysiology, particularly during aging.
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Affiliation(s)
- Valérie Pierrefite-Carle
- UMR E-4320 TIRO-MATOs CEA/iBEB, Université Nice Sophia Antipolis, Faculté de Médecine Nice, France.
| | - Sabine Santucci-Darmanin
- UMR E-4320 TIRO-MATOs CEA/iBEB, Université Nice Sophia Antipolis, Faculté de Médecine Nice, France
| | - Véronique Breuil
- UMR E-4320 TIRO-MATOs CEA/iBEB, Université Nice Sophia Antipolis, Faculté de Médecine Nice, France; Service de Rhumatologie, CHU de Nice, Nice, France
| | - Olivier Camuzard
- UMR E-4320 TIRO-MATOs CEA/iBEB, Université Nice Sophia Antipolis, Faculté de Médecine Nice, France; Service de Chirurgie Réparatrice et de la main, CHU de Nice, Nice, France
| | - Georges F Carle
- UMR E-4320 TIRO-MATOs CEA/iBEB, Université Nice Sophia Antipolis, Faculté de Médecine Nice, France
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40
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Jentsch TJ. Discovery of CLC transport proteins: cloning, structure, function and pathophysiology. J Physiol 2015; 593:4091-109. [PMID: 25590607 DOI: 10.1113/jp270043] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Accepted: 01/11/2015] [Indexed: 02/06/2023] Open
Abstract
After providing a personal description of the convoluted path leading 25 years ago to the molecular identification of the Torpedo Cl(-) channel ClC-0 and the discovery of the CLC gene family, I succinctly describe the general structural and functional features of these ion transporters before giving a short overview of mammalian CLCs. These can be categorized into plasma membrane Cl(-) channels and vesicular Cl(-) /H(+) -exchangers. They are involved in the regulation of membrane excitability, transepithelial transport, extracellular ion homeostasis, endocytosis and lysosomal function. Diseases caused by CLC dysfunction include myotonia, neurodegeneration, deafness, blindness, leukodystrophy, male infertility, renal salt loss, kidney stones and osteopetrosis, revealing a surprisingly broad spectrum of biological roles for chloride transport that was unsuspected when I set out to clone the first voltage-gated chloride channel.
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Affiliation(s)
- Thomas J Jentsch
- Leibniz-Institut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin (MDC), Berlin, Germany
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41
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Wang G, Nauseef WM. Salt, chloride, bleach, and innate host defense. J Leukoc Biol 2015; 98:163-72. [PMID: 26048979 DOI: 10.1189/jlb.4ru0315-109r] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 04/27/2015] [Indexed: 12/17/2022] Open
Abstract
Salt provides 2 life-essential elements: sodium and chlorine. Chloride, the ionic form of chlorine, derived exclusively from dietary absorption and constituting the most abundant anion in the human body, plays critical roles in many vital physiologic functions, from fluid retention and secretion to osmotic maintenance and pH balance. However, an often overlooked role of chloride is its function in innate host defense against infection. Chloride serves as a substrate for the generation of the potent microbicide chlorine bleach by stimulated neutrophils and also contributes to regulation of ionic homeostasis for optimal antimicrobial activity within phagosomes. An inadequate supply of chloride to phagocytes and their phagosomes, such as in CF disease and other chloride channel disorders, severely compromises host defense against infection. We provide an overview of the roles that chloride plays in normal innate immunity, highlighting specific links between defective chloride channel function and failures in host defense.
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Affiliation(s)
- Guoshun Wang
- *Departments of Microbiology and Immunology, Genetics, and Medicine, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA; and Department of Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, and Veterans Administration Medical Center, Iowa City, Iowa, USA
| | - William M Nauseef
- *Departments of Microbiology and Immunology, Genetics, and Medicine, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA; and Department of Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, and Veterans Administration Medical Center, Iowa City, Iowa, USA
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42
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Wen X, Lacruz RS, Paine ML. Dental and Cranial Pathologies in Mice Lacking the Cl(-) /H(+) -Exchanger ClC-7. Anat Rec (Hoboken) 2015; 298:1502-8. [PMID: 25663454 DOI: 10.1002/ar.23118] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2014] [Revised: 12/01/2014] [Accepted: 12/05/2014] [Indexed: 11/10/2022]
Abstract
ClC-7 is a 2Cl(-) /1H(+) -exchanger expressed at late endosomes and lysosomes, as well as the ruffled border of osteoclasts. ClC-7 deficiencies in mice and humans lead to impaired osteoclast function and therefore osteopetrosis. Failure of tooth eruption is also apparent in ClC-7 mutant animals, and this has been attributed to the osteoclast dysfunction and the subsequent defect in alveolar bone resorptive activity surrounding tooth roots. Ameloblasts also express ClC-7, and this study aims to determine the significance of ClC-7 in enamel formation by examining the dentitions of ClC-7 mutant mice. Micro-CT analysis revealed that the molar teeth of 3-week old ClC-7 mutant mice had no roots, and the incisors were smaller than their age-matched controls. Despite these notable developmental differences, the enamel and dentin densities of the mutant mice were comparable to those of the wild-type littermates. Scanning electron microscopy showed normal enamel crystallite and prismatic organization in the ClC-7 mutant mice, although the enamel was thinner (hypoplastic) than in controls. These results suggested that ClC-7 was not critical to enamel and dentin formation, and the observed tooth defects may be related more to a resulting alveolar bone phenotype. Micro-CT analysis also revealed abnormal features in the calvarial bones of the mutant mice. The cranial sutures in ClC-7 mutant mice remained open compared to the closed sutures seen in the control mice at 3 weeks. These data demonstrate that ClC-7 deficiency impacts the development of the dentition and calvaria, but does not significantly disrupt amelogenesis.
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Affiliation(s)
- Xin Wen
- Herman Ostrow School of Dentistry of USC, Center for Craniofacial Molecular Biology, University of Southern California, Los Angeles, USA
| | - Rodrigo S Lacruz
- Department of Basic Science and Craniofacial Biology, College of Dentistry, New York University, New York, New York, USA
| | - Michael L Paine
- Herman Ostrow School of Dentistry of USC, Center for Craniofacial Molecular Biology, University of Southern California, Los Angeles, USA
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43
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Weinert S, Jabs S, Hohensee S, Chan WL, Kornak U, Jentsch TJ. Transport activity and presence of ClC-7/Ostm1 complex account for different cellular functions. EMBO Rep 2014; 15:784-91. [PMID: 24820037 DOI: 10.15252/embr.201438553] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Loss of the lysosomal ClC-7/Ostm1 2Cl(-)/H(+) exchanger causes lysosomal storage disease and osteopetrosis in humans and additionally changes fur colour in mice. Its conversion into a Cl(-) conductance in Clcn7(unc/unc) mice entails similarly severe lysosomal storage, but less severe osteopetrosis and no change in fur colour. To elucidate the basis for these phenotypical differences, we generated Clcn7(td/td) mice expressing an ion transport-deficient mutant. Their osteopetrosis was as severe as in Clcn7(-/-) mice, suggesting that the electric shunt provided by ClC-7(unc) can partially rescue osteoclast function. The normal coat colour of Clcn7(td/td) mice and their less severe neurodegeneration suggested that the ClC-7 protein, even when lacking measurable ion transport activity, is sufficient for hair pigmentation and that the conductance of ClC-7(unc) is harmful for neurons. Our in vivo structure-function analysis of ClC-7 reveals that both protein-protein interactions and ion transport must be considered in the pathogenesis of ClC-7-related diseases.
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Affiliation(s)
- Stefanie Weinert
- Leibniz-Institut für Molekulare Pharmakologie (FMP), Berlin, Germany Max-Delbrück-Centrum für Molekulare Medizin (MDC), Berlin, Germany
| | - Sabrina Jabs
- Leibniz-Institut für Molekulare Pharmakologie (FMP), Berlin, Germany Max-Delbrück-Centrum für Molekulare Medizin (MDC), Berlin, Germany
| | - Svea Hohensee
- Leibniz-Institut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Wing Lee Chan
- Institut für Humangenetik, Charité Universitätsmedizin Berlin, Berlin, Germany Max-Planck-Institut für Molekulare Genetik, Berlin, Germany
| | - Uwe Kornak
- Institut für Humangenetik, Charité Universitätsmedizin Berlin, Berlin, Germany Max-Planck-Institut für Molekulare Genetik, Berlin, Germany
| | - Thomas J Jentsch
- Leibniz-Institut für Molekulare Pharmakologie (FMP), Berlin, Germany Max-Delbrück-Centrum für Molekulare Medizin (MDC), Berlin, Germany Neurocure Cluster of Excellence, Charité Universitätsmedizin Berlin, Berlin, Germany
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44
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Héraud C, Griffiths A, Pandruvada SNM, Kilimann MW, Pata M, Vacher J. Severe neurodegeneration with impaired autophagy mechanism triggered by ostm1 deficiency. J Biol Chem 2014; 289:13912-25. [PMID: 24719316 DOI: 10.1074/jbc.m113.537233] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Loss of Ostm1 leads to the most severe form of osteopetrosis in mice and humans. Because functional rescue of the osteopetrotic defect in these mice extended their lifespan from ∼3 weeks to 6 weeks, this unraveled a second essential role of Ostm1. We discovered that Ostm1 is highly expressed in the mouse brain in neurons, microglia, and astrocytes. At 3-4 weeks of age, mice with Ostm1 loss showed 3-10-fold stimulation of reactive gliosis, with an increased astrocyte cell population and microglia activation. This inflammatory response was associated with marked retinal photoreceptor degeneration and massive neuronal loss in the brain. Intracellular characterization of neurons revealed abnormal storage of carbohydrates, lipids, and ubiquitinated proteins, combined with marked accumulation of autophagosomes that causes frequent axonal swelling. Stimulation of autophagy was provided by specific markers and by significant down-regulation of the mammalian target of rapamycin signaling, identifying a cellular pathologic mechanism. A series of transgenic mouse lines specifically targeted to distinct central nervous system cell subpopulations determined that Ostm1 has a primary and autonomous role in neuronal homeostasis. Complete functional complementation demonstrated that the development of severe and rapid neurodegeneration in these mice is independent of the hematopoietic lineage and has clinical implications for treatment of osteopetrosis. Importantly, this study establishes a novel neurodegenerative mouse model critical for understanding the multistep pathogenic cascade of cellular autophagy disorders toward therapeutic strategy design.
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Affiliation(s)
- Céline Héraud
- From the Institut de Recherches Cliniques de Montréal (IRCM), Département de Médecine, Université de Montréal, Montréal, Québec H2W 1R7, Canada, the Department of Medicine, Division of Experimental Medicine, McGill University, Montréal, Québec H3A 1A3, Canada
| | - Adam Griffiths
- From the Institut de Recherches Cliniques de Montréal (IRCM), Département de Médecine, Université de Montréal, Montréal, Québec H2W 1R7, Canada, the Department of Medicine, Division of Experimental Medicine, McGill University, Montréal, Québec H3A 1A3, Canada
| | - Subramanya N M Pandruvada
- From the Institut de Recherches Cliniques de Montréal (IRCM), Département de Médecine, Université de Montréal, Montréal, Québec H2W 1R7, Canada, the Department of Medicine, Division of Experimental Medicine, McGill University, Montréal, Québec H3A 1A3, Canada
| | - Manfred W Kilimann
- the Department of Otolaryngology, Göttingen University Medical Center, D-37075 Göttingen, Germany, and the Department of Molecular Neurobiology, Max-Planck-Institute for Experimental Medicine, D-37075 Göttingen, Germany
| | - Monica Pata
- From the Institut de Recherches Cliniques de Montréal (IRCM), Département de Médecine, Université de Montréal, Montréal, Québec H2W 1R7, Canada, the Department of Medicine, Division of Experimental Medicine, McGill University, Montréal, Québec H3A 1A3, Canada
| | - Jean Vacher
- From the Institut de Recherches Cliniques de Montréal (IRCM), Département de Médecine, Université de Montréal, Montréal, Québec H2W 1R7, Canada, the Department of Medicine, Division of Experimental Medicine, McGill University, Montréal, Québec H3A 1A3, Canada,
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45
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Coudert AE, Del Fattore A, Baulard C, Olaso R, Schiltz C, Collet C, Teti A, de Vernejoul MC. Differentially expressed genes in autosomal dominant osteopetrosis type II osteoclasts reveal known and novel pathways for osteoclast biology. J Transl Med 2014; 94:275-85. [PMID: 24336069 DOI: 10.1038/labinvest.2013.140] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Revised: 09/25/2013] [Accepted: 10/22/2013] [Indexed: 01/09/2023] Open
Abstract
Autosomal dominant osteopetrosis type II (ADO II) is a rare, heritable bone disorder characterized by a high bone mass and insufficient osteoclast activity. Mutations in the CLCN7 gene have been reported to cause ADO II. To gain novel insights into the pathways dysregulated in ADOII osteoclasts, we identified changes in gene expression in osteoclasts from patients with a heterozygous mutation of CLCN7. To do this, we carried out a transcriptomic study comparing gene expression in the osteoclasts of patients with ADO II and healthy donors. Our data show that, according to our selection criteria, 182 genes were differentially expressed in osteoclasts from patients and controls. From the 18 displaying the highest change in microarray, we confirmed differential expression for seven by qPCR. Although two of them have previously been found to be expressed in osteoclasts (ITGB5 and SERPINE2), the other five (CES1 (carboxyl esterase 1), UCHL1 (ubiquitin carboxy-terminal esterase L1, also known as ubiquitin thiolesterase), WARS (tryptophanyl-tRNA synthetase), GBP4 (guanylate-binding protein 4), and PRF1) are not yet known to have a role in this cell type. At the protein level, we confirmed elevated expression of ITGB5 and reduced expression of WARS, PRF1, and SERPINE2. Transfection of ClC-7 harboring the G215R mutation into osteoclasts resulted in an increased ITGB5 and reduced PRF1 expression of borderline significance. Finally, we observed that the ADO II patients presented a normal or increased serum level of bone formation markers, demonstrating a coupling between dysfunctional osteoclasts and osteoblasts. Sphingosine kinase 1 mRNA was expressed at the same level in ADO II and control osteoclasts. In conclusion, these data suggest that in addition to an acidification dysfunction caused by the CLCN7 mutation, a change in ITGB5, PRF1, WARS, and SERPINE2 expression could be part of the osteoclastic phenotype of ADO II.
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Affiliation(s)
- Amélie E Coudert
- Institut National de la Santé et de la Recherche Médicale U606, Hôpital Lariboisière, Paris, France
| | - Andrea Del Fattore
- Regenerative Medicine Unit, Ospedale Pediatrico Bambino Gesù, Rome, Italy
| | - Céline Baulard
- CEA-Institut de Génomique, Centre National de Genotypage, Evry, France
| | - Robert Olaso
- CEA-Institut de Génomique, Centre National de Genotypage, Evry, France
| | - Corinne Schiltz
- Institut National de la Santé et de la Recherche Médicale U606, Hôpital Lariboisière, Paris, France
| | - Corinne Collet
- 1] Institut National de la Santé et de la Recherche Médicale U606, Hôpital Lariboisière, Paris, France [2] Service de Biochimie, Hôpital Lariboisière, Paris, France
| | - Anna Teti
- Department of Biotechnological and Applied Clinical Sciences, Università degli studi dell'Aquila, L'Aquila, Italy
| | - Marie-Christine de Vernejoul
- 1] Institut National de la Santé et de la Recherche Médicale U606, Hôpital Lariboisière, Paris, France [2] INSERM U606, Os et articulations, Bâtiment Viggo Petersen, Secteur Viole, Fédération de Rhumatologie, Hôpital Lariboisière, Paris, France
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46
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Stauber T, Weinert S, Jentsch TJ. Cell biology and physiology of CLC chloride channels and transporters. Compr Physiol 2013; 2:1701-44. [PMID: 23723021 DOI: 10.1002/cphy.c110038] [Citation(s) in RCA: 112] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Proteins of the CLC gene family assemble to homo- or sometimes heterodimers and either function as Cl(-) channels or as Cl(-)/H(+)-exchangers. CLC proteins are present in all phyla. Detailed structural information is available from crystal structures of bacterial and algal CLCs. Mammals express nine CLC genes, four of which encode Cl(-) channels and five 2Cl(-)/H(+)-exchangers. Two accessory β-subunits are known: (1) barttin and (2) Ostm1. ClC-Ka and ClC-Kb Cl(-) channels need barttin, whereas Ostm1 is required for the function of the lysosomal ClC-7 2Cl(-)/H(+)-exchanger. ClC-1, -2, -Ka and -Kb Cl(-) channels reside in the plasma membrane and function in the control of electrical excitability of muscles or neurons, in extra- and intracellular ion homeostasis, and in transepithelial transport. The mainly endosomal/lysosomal Cl(-)/H(+)-exchangers ClC-3 to ClC-7 may facilitate vesicular acidification by shunting currents of proton pumps and increase vesicular Cl(-) concentration. ClC-3 is also present on synaptic vesicles, whereas ClC-4 and -5 can reach the plasma membrane to some extent. ClC-7/Ostm1 is coinserted with the vesicular H(+)-ATPase into the acid-secreting ruffled border membrane of osteoclasts. Mice or humans lacking ClC-7 or Ostm1 display osteopetrosis and lysosomal storage disease. Disruption of the endosomal ClC-5 Cl(-)/H(+)-exchanger leads to proteinuria and Dent's disease. Mouse models in which ClC-5 or ClC-7 is converted to uncoupled Cl(-) conductors suggest an important role of vesicular Cl(-) accumulation in these pathologies. The important functions of CLC Cl(-) channels were also revealed by human diseases and mouse models, with phenotypes including myotonia, renal loss of salt and water, deafness, blindness, leukodystrophy, and male infertility.
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Affiliation(s)
- Tobias Stauber
- Leibniz-Institut für Molekulare Pharmakologie FMP and Max-Delbrück-Centrum für Molekulare Medizin MDC, Berlin, Germany
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47
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Wang F, Yu L, Monopoli MP, Sandin P, Mahon E, Salvati A, Dawson KA. The biomolecular corona is retained during nanoparticle uptake and protects the cells from the damage induced by cationic nanoparticles until degraded in the lysosomes. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2013; 9:1159-68. [DOI: 10.1016/j.nano.2013.04.010] [Citation(s) in RCA: 310] [Impact Index Per Article: 28.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Revised: 04/17/2013] [Accepted: 04/25/2013] [Indexed: 12/19/2022]
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48
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Sartelet A, Stauber T, Coppieters W, Ludwig CF, Fasquelle C, Druet T, Zhang Z, Ahariz N, Cambisano N, Jentsch TJ, Charlier C. A missense mutation accelerating the gating of the lysosomal Cl-/H+-exchanger ClC-7/Ostm1 causes osteopetrosis with gingival hamartomas in cattle. Dis Model Mech 2013; 7:119-28. [PMID: 24159188 PMCID: PMC3882054 DOI: 10.1242/dmm.012500] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Chloride-proton exchange by the lysosomal anion transporter ClC-7/Ostm1 is of pivotal importance for the physiology of lysosomes and bone resorption. Mice lacking either ClC-7 or Ostm1 develop a lysosomal storage disease and mutations in either protein have been found to underlie osteopetrosis in mice and humans. Some human disease-causing CLCN7 mutations accelerate the usually slow voltage-dependent gating of ClC-7/Ostm1. However, it has remained unclear whether the fastened kinetics is indeed causative for the disease. Here we identified and characterized a new deleterious ClC-7 mutation in Belgian Blue cattle with a severe symptomatology including perinatal lethality and in most cases gingival hamartomas. By autozygosity mapping and genome-wide sequencing we found a handful of candidate variants, including a cluster of three private SNPs causing the substitution of a conserved tyrosine in the CBS2 domain of ClC-7 by glutamine. The case for ClC-7 was strengthened by subsequent examination of affected calves that revealed severe osteopetrosis. The Y750Q mutation largely preserved the lysosomal localization and assembly of ClC-7/Ostm1, but drastically accelerated its activation by membrane depolarization. These data provide first evidence that accelerated ClC-7/Ostm1 gating per se is deleterious, highlighting a physiological importance of the slow voltage-activation of ClC-7/Ostm1 in lysosomal function and bone resorption.
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Affiliation(s)
- Arnaud Sartelet
- Unit of Animal Genomics, GIGA-R and Faculty of Veterinary Medicine, University of Liège (B34), 1 Avenue de l'Hôpital, 4000-Liège (Sart Tilman), Belgium
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Sobacchi C, Schulz A, Coxon FP, Villa A, Helfrich MH. Osteopetrosis: genetics, treatment and new insights into osteoclast function. Nat Rev Endocrinol 2013; 9:522-36. [PMID: 23877423 DOI: 10.1038/nrendo.2013.137] [Citation(s) in RCA: 363] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Osteopetrosis is a genetic condition of increased bone mass, which is caused by defects in osteoclast formation and function. Both autosomal recessive and autosomal dominant forms exist, but this Review focuses on autosomal recessive osteopetrosis (ARO), also known as malignant infantile osteopetrosis. The genetic basis of this disease is now largely uncovered: mutations in TCIRG1, CLCN7, OSTM1, SNX10 and PLEKHM1 lead to osteoclast-rich ARO (in which osteoclasts are abundant but have severely impaired resorptive function), whereas mutations in TNFSF11 and TNFRSF11A lead to osteoclast-poor ARO. In osteoclast-rich ARO, impaired endosomal and lysosomal vesicle trafficking results in defective osteoclast ruffled-border formation and, hence, the inability to resorb bone and mineralized cartilage. ARO presents soon after birth and can be fatal if left untreated. However, the disease is heterogeneous in clinical presentation and often misdiagnosed. This article describes the genetics of ARO and discusses the diagnostic role of next-generation sequencing methods. The management of affected patients, including guidelines for the indication of haematopoietic stem cell transplantation (which can provide a cure for many types of ARO), are outlined. Finally, novel treatments, including preclinical data on in utero stem cell treatment, RANKL replacement therapy and denosumab therapy for hypercalcaemia are also discussed.
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Affiliation(s)
- Cristina Sobacchi
- Unit Of Support/Institute of Genetic and Biomedical Research, Milan Unit, National Research Council, Humanitas Clinical and Research Centre, Via Manzoni 113, 20089 Rozzano, Italy
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Lee D, Gleich K, Fraser SA, Katerelos M, Mount PF, Power DA. Limited capacity of proximal tubular proteolysis in mice with proteinuria. Am J Physiol Renal Physiol 2013; 304:F1009-19. [PMID: 23344573 DOI: 10.1152/ajprenal.00601.2012] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Albuminuria is associated with the additional loss in the urine of small molecular weight proteins normally degraded by the proximal convoluted tubule (PCT), and competition for binding to the megalin/cubilin reuptake system has been considered the likely cause. We have previously reported that deficiency of the intrinsic lysosomal protein Limp-2 causes tubular proteinuria due to reduced fusion of endosomes with lysosomes in the PCT leading to inadequate proteolysis. To determine whether this mechanism also contributes to the tubular proteinuria induced by albumin overload in normal mice, wild-type (WT) mice received daily BSA injections intraperitoneally for 10 days, using untreated Limp-2(-/-) mice as positive controls for inadequate proteolysis. BSA overload induced significant urinary loss of megalin and cubilin ligands in WT mice. Tubular uptake of Alexa-conjugated BSA, administered by intravenous injection, was not reduced in the PCT of mice receiving intraperitoneal BSA. Expression of the tubular protein receptor megalin was also unchanged. There was a delay in proteolysis of reabsorbed proteins in WT mice receiving BSA, evidenced by an increased quantity of retinol-binding protein (RBP) in the kidney cortex, increased basal distribution of endocytosed RBP in cells of the PCT, and persistence of exogenous Alexa-conjugated BSA and RBP after injection. Upregulation of cathepsin L and normal fusion of lysosomes with endosomes were apparently not sufficient to maintain normal clearance of endocytosed proteins. The data suggest that in the presence of competition from albumin overload, reabsorption of filtered proteins is limited by the capacity of lysosomal degradation rather than receptor-mediated endocytosis.
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Affiliation(s)
- D Lee
- Department of Nephrology, Austin Health, Studley Rd., Heidelberg, Victoria 3084, Australia.
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