Search

Your search keyword '"Andrini, Olga"' showing total 30 results
Start Over Author "Andrini, Olga"
30 results on '"Andrini, Olga"'

2. ClC-K Kidney Chloride Channels: From Structure to Pathology

Author

Andrini, Olga, Eladari, Dominique, Picard, Nicolas, Michel, Martin C., Editor-in-Chief, Barrett, James E., Editorial Board Member, Centurión, David, Editorial Board Member, Flockerzi, Veit, Editorial Board Member, Geppetti, Pierangelo, Editorial Board Member, Hofmann, Franz B., Editorial Board Member, Meier, Kathryn Elaine, Editorial Board Member, Page, Clive P., Editorial Board Member, Wang, KeWei, Editorial Board Member, and Fahlke, Christoph, editor

Published
2024
Full Text
View/download PDF

5. Constitutive sodium permeability in a Caenorhabditis elegans two-pore domain potassium channel.

Author

Andrini, Olga, Soussia, Ismail Ben, Tardy, Philippe, Walker, Denise S., Peña-Varas, Carlos, Ramírez, David, Gendrel, Marie, Mercier, Marine, El Mouridi, Sonia, Leclercq-Blondel, Alice, González, Wendy, Schafer, William R., Jospin, Maelle, and Boulin, Thomas

Subjects
*POTASSIUM channels, *MOLECULAR dynamics, *CELL membranes, *IONS, *CAENORHABDITIS elegans
Abstract

Two-pore domain potassium (K2P) channels play a central role in modulating cellular excitability and neuronal function. The unique structure of the selectivity filter in K2P and other potassium channels determines their ability to allow the selective passage of potassium ions across cell membranes. The nematode C. elegans has one of the largest K2P families, with 47 subunit-coding genes. This remarkable expansion has been accompanied by the evolution of atypical selectivity filter sequences that diverge from the canonical TxGYG motif. Whether and how this sequence variation may impact the function of K2P channels has not been investigated so far. Here, we show that the UNC-58 K2P channel is constitutively permeable to sodium ions and that a cysteine residue in its selectivity filter is responsible for this atypical behavior. Indeed, by performing in vivo electrophysiological recordings and Ca2+ imaging experiments, we demonstrate that UNC-58 has a depolarizing effect in muscles and sensory neurons. Consistently, unc-58 gain-of-function mutants are hypercontracted, unlike the relaxed phenotype observed in hyperactive mutants of many neuromuscular K2P channels. Finally, by combining molecular dynamics simulations with functional studies in Xenopus laevis oocytes, we show that the atypical cysteine residue plays a key role in the unconventional sodium permeability of UNC-58. As predicting the consequences of selectivity filter sequence variations in silico remains a major challenge, our study illustrates how functional experiments are essential to determine the contribution of such unusual potassium channels to the electrical profile of excitable cells. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

9. Clinical and Genetic Spectrum of Bartter Syndrome Type 3

Author

Seys, Elsa, Andrini, Olga, Keck, Mathilde, Mansour-Hendili, Lamisse, Courand, Pierre-Yves, Simian, Christophe, Deschenes, Georges, Kwon, Theresa, Bertholet-Thomas, Aurélia, Bobrie, Guillaume, Borde, Jean Sébastien, Bourdat-Michel, Guylhène, Decramer, Stéphane, Cailliez, Mathilde, Krug, Pauline, Cozette, Paul, Delbet, Jean Daniel, Dubourg, Laurence, Chaveau, Dominique, Fila, Marc, Jourde-Chiche, Noémie, Knebelmann, Bertrand, Lavocat, Marie-Pierre, Lemoine, Sandrine, Djeddi, Djamal, Llanas, Brigitte, Louillet, Ferielle, Merieau, Elodie, Mileva, Maria, Mota-Vieira, Luisa, Mousson, Christiane, Nobili, François, Novo, Robert, Roussey-Kesler, Gwenaëlle, Vrillon, Isabelle, Walsh, Stephen B., Teulon, Jacques, Blanchard, Anne, and Vargas-Poussou, Rosa

Published
2017
Full Text
View/download PDF

13. Analysis of CLCNKB mutations at dimer‐interface, calcium‐binding site, and pore reveals a variety of functional alterations in ClC‐Kb channel leading to Bartter syndrome

Author

Bignon, Yohan, primary, Sakhi, Imene, additional, Bitam, Sara, additional, Bakouh, Naziha, additional, Keck, Mathilde, additional, Frachon, Nadia, additional, Paulais, Marc, additional, Planelles, Gabrielle, additional, Teulon, Jacques, additional, and Andrini, Olga, additional

Published
2019
Full Text
View/download PDF

14. Analysis of CLCNKB mutations at dimer‐interface, calcium‐binding site, and pore reveals a variety of functional alterations in ClC‐Kb channel leading to Bartter syndrome.

Author

Bignon, Yohan, Sakhi, Imene, Bitam, Sara, Bakouh, Naziha, Keck, Mathilde, Frachon, Nadia, Paulais, Marc, Planelles, Gabrielle, Teulon, Jacques, and Andrini, Olga

Abstract

Pathological missense mutations in CLCNKB gene give a wide spectrum of clinical phenotypes in Bartter syndrome type III patients. Molecular analysis of the mutated ClC‐Kb channels can be helpful to classify the mutations according to their functional alteration. We investigated the functional consequences of nine mutations in the CLCNKB gene causing Bartter syndrome. We first established that all tested mutations lead to decreased ClC‐Kb currents. Combining electrophysiological and biochemical methods in Xenopus laevis oocytes and in MDCKII cells, we identified three classes of mutations. One class is characterized by altered channel trafficking. p.A210V, p.P216L, p.G424R, and p.G437R are totally or partially retained in the endoplasmic reticulum. p.S218N is characterized by reduced channel insertion at the plasma membrane and altered pH‐sensitivity; thus, it falls in the second class of mutations. Finally, we found a novel class of functionally inactivated mutants normally present at the plasma membrane. Indeed, we found that p.A204T alters the pH‐sensitivity, p.A254V abolishes the calcium‐sensitivity. p.G219C and p.G465R are probably partially inactive at the plasma membrane. In conclusion, most pathogenic mutants accumulate partly or totally in intracellular compartments, but some mutants are normally present at the membrane surface and simultaneously show a large range of altered channel gating properties. [ABSTRACT FROM AUTHOR]

Published
2020
Full Text
View/download PDF

16. Renal Chloride Channels in Relation to Sodium Chloride Transport

Author

Planelles, Gabrielle, Sepúlveda, Francisco, Andrini, Olga, Terjung, Ronald, Pinelli, Laurent, Nissant, Antoine, Edwards, Aurélie, Lourdel, Stéphane, Teulon, Jacques, Paulais, Marc, Canalopathies épithéliales: la mucoviscidose et autres maladies, Institut Necker Enfants-Malades (INEM - UM 111 (UMR 8253 / U1151)), Université Paris Descartes - Paris 5 (UPD5)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Descartes - Paris 5 (UPD5)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Centro de Estudios Científicos (CECs), Centre de Recherche des Cordeliers (CRC), Université Paris Diderot - Paris 7 (UPD7)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Descartes - Paris 5 (UPD5)-Institut National de la Santé et de la Recherche Médicale (INSERM), Department of Chemical and Biological Engineering, Tufts University [Medford], Centre de Recherche des Cordeliers (CRC (UMR_S 872)), Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Descartes - Paris 5 (UPD5)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), and Université Paris Diderot - Paris 7 (UPD7)-École pratique des hautes études (EPHE)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Descartes - Paris 5 (UPD5)-Institut National de la Santé et de la Recherche Médicale (INSERM)

Subjects
urogenital system, [SDV]Life Sciences [q-bio], [SDV.BC]Life Sciences [q-bio]/Cellular Biology
Abstract

International audience; ClC-K2, a member of the ClC family of Cl(-) channels and transporters, forms the major basolateral Cl(-) conductance in distal nephron epithelial cells and therefore plays a central role in renal Cl(-) absorption. However, its regulation remains largely unknown because of the fact that recombinant ClC-K2 has not yet been studied at the single-channel level. In the present study, we investigate the effects of voltage, pH, Cl(-), and Ca(2+) on native ClC-K2 in the basolateral membrane of intercalated cells from the mouse connecting tubule. The ∼10-pS channel shows a steep voltage dependence such that channel activity increases with membrane depolarization. Intracellular pH (pHi) and extracellular pH (pHo) differentially modulate the voltage dependence curve: alkaline pHi flattens the curve by causing an increase in activity at negative voltages, whereas alkaline pHo shifts the curve toward negative voltages. In addition, pHi, pHo, and extracellular Ca(2+) strongly increase activity, mainly because of an increase in the number of active channels with a comparatively minor effect on channel open probability. Furthermore, voltage alters both the number of active channels and their open probability, whereas intracellular Cl(-) has little influence. We propose that changes in the number of active channels correspond to them entering or leaving an inactivated state, whereas modulation of open probability corresponds to common gating by these channels. We suggest that pH, through the combined effects of pHi and pHo on ClC-K2, might be a key regulator of NaCl absorption and Cl(-)/HCO3 (-) exchange in type B intercalated cells.

Published
2016
Full Text
View/download PDF

17. Novel CLCNKB mutations causing Bartter syndrome affect channel surface expression Human Mutation

Author

Keck, Mathilde, Andrini, Olga, Lahuna, Olivier, Burgos, Johanna, Cid, L Pablo, Sepúlveda, Francisco, L'Hoste, Sébastien, Blanchard, Anne, Vargas-Poussou, Rosa, Lourdel, Stéphane, Teulon, Jacques, Cid, L. Pablo, L‘Hoste, Sébastien, Centre de Recherche des Cordeliers (CRC (UMR_S_1138 / U1138)), École pratique des hautes études (EPHE)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris Descartes - Paris 5 (UPD5)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Sorbonne Université (SU), Centre de Recherche des Cordeliers (CRC), Université Paris Diderot - Paris 7 (UPD7)-École pratique des hautes études (EPHE)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Descartes - Paris 5 (UPD5)-Institut National de la Santé et de la Recherche Médicale (INSERM), Institut Cochin (IC UM3 (UMR 8104 / U1016)), Université Paris Descartes - Paris 5 (UPD5)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Centro de Estudios Científicos (CECs), Centre de Recherche des Cordeliers (CRC (UMR_S 872)), Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Descartes - Paris 5 (UPD5)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Université Paris Descartes - Faculté de Médecine (UPD5 Médecine), Université Paris Descartes - Paris 5 (UPD5), Service de Génétique [AP-HP Hôpital Européen Georges Pompidou, Paris], Hôpital Européen Georges Pompidou [APHP] (HEGP), Assistance publique - Hôpitaux de Paris (AP-HP) (APHP)-Hôpitaux Universitaires Paris Ouest - Hôpitaux Universitaires Île de France Ouest (HUPO)-Assistance publique - Hôpitaux de Paris (AP-HP) (APHP)-Hôpitaux Universitaires Paris Ouest - Hôpitaux Universitaires Île de France Ouest (HUPO), Max Planck Institute for Biophysical Chemistry (MPI-BPC), Max-Planck-Gesellschaft, Service de génétique [CHU HEGP], Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Hôpital Européen Georges Pompidou [APHP] (HEGP), Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Hôpitaux Universitaires Paris Ouest - Hôpitaux Universitaires Île de France Ouest (HUPO)-Hôpitaux Universitaires Paris Ouest - Hôpitaux Universitaires Île de France Ouest (HUPO), UFR Médecine [Santé] - Université Paris Cité (UFR Médecine UPCité), Université Paris Cité (UPCité), Centre d'Investigation Clinique - Epidemiologie Clinique/essais Cliniques [CHU HEGP], Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Hôpitaux Universitaires Paris Ouest - Hôpitaux Universitaires Île de France Ouest (HUPO)-Hôpitaux Universitaires Paris Ouest - Hôpitaux Universitaires Île de France Ouest (HUPO)-Institut National de la Santé et de la Recherche Médicale (INSERM), Paris-Centre de Recherche Cardiovasculaire (PARCC (UMR_S 970/ U970)), Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Hôpitaux Universitaires Paris Ouest - Hôpitaux Universitaires Île de France Ouest (HUPO)-Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Hôpitaux Universitaires Paris Ouest - Hôpitaux Universitaires Île de France Ouest (HUPO)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Paris Cité (UPCité), Évolution, Écologie et Paléontologie (Evo-Eco-Paleo) - UMR 8198 (Evo-Eco-Paléo), Université de Lille-Centre National de la Recherche Scientifique (CNRS), Université de Nantes - UFR Odontologie, Université de Nantes (UN), Université Paris Diderot - Paris 7 (UPD7)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Descartes - Paris 5 (UPD5)-Institut National de la Santé et de la Recherche Médicale (INSERM), Université Paris Descartes - Paris 5 (UPD5)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Université de Paris - UFR Médecine Paris Centre [Santé] (UP Médecine Paris Centre), Université de Paris (UP), Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Hôpitaux Universitaires Paris Ouest - Hôpitaux Universitaires Île de France Ouest (HUPO)-Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Hôpitaux Universitaires Paris Ouest - Hôpitaux Universitaires Île de France Ouest (HUPO)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université de Paris (UP), Hôpitaux Universitaires Paris Ouest - Hôpitaux Universitaires Île de France Ouest (HUPO)-Assistance publique - Hôpitaux de Paris (AP-HP) (APHP)-Hôpitaux Universitaires Paris Ouest - Hôpitaux Universitaires Île de France Ouest (HUPO)-Assistance publique - Hôpitaux de Paris (AP-HP) (APHP), Service de Pharmacologie, toxicologie et pharmacovigilance [CHU Limoges], CHU Limoges, University of California [San Diego] (UC San Diego), University of California, Paris-Centre de Recherche Cardiovasculaire (PARCC - UMR-S U970), Université Paris Descartes - Paris 5 (UPD5)-Hôpital Européen Georges Pompidou [APHP] (HEGP), Assistance publique - Hôpitaux de Paris (AP-HP) (APHP)-Hôpitaux Universitaires Paris Ouest - Hôpitaux Universitaires Île de France Ouest (HUPO)-Assistance publique - Hôpitaux de Paris (AP-HP) (APHP)-Hôpitaux Universitaires Paris Ouest - Hôpitaux Universitaires Île de France Ouest (HUPO)-Institut National de la Santé et de la Recherche Médicale (INSERM), Service de Physiologie [Georges-Pompidou], Assistance publique - Hôpitaux de Paris (AP-HP) (APHP)-Hôpital Européen Georges Pompidou [APHP] (HEGP), Assistance publique - Hôpitaux de Paris (AP-HP) (APHP)-Hôpitaux Universitaires Paris Ouest - Hôpitaux Universitaires Île de France Ouest (HUPO)-Hôpitaux Universitaires Paris Ouest - Hôpitaux Universitaires Île de France Ouest (HUPO)-Université Paris Descartes - Paris 5 (UPD5), Hôpitaux Universitaires Paris Ouest - Hôpitaux Universitaires Île de France Ouest (HUPO)-Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Hôpitaux Universitaires Paris Ouest - Hôpitaux Universitaires Île de France Ouest (HUPO), Université de Paris - Faculté de Médecine Paris Centre (UP Médecine Paris Centre), Centro de Estudios Científicos, Valdivia, Hôpitaux Universitaires Paris Ouest - Hôpitaux Universitaires Île de France Ouest (HUPO)-Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Hôpitaux Universitaires Paris Ouest - Hôpitaux Universitaires Île de France Ouest (HUPO)-Institut National de la Santé et de la Recherche Médicale (INSERM), Hôpitaux Universitaires Paris Ouest - Hôpitaux Universitaires Île de France Ouest (HUPO)-Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Hôpitaux Universitaires Paris Ouest - Hôpitaux Universitaires Île de France Ouest (HUPO)-Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université de Paris (UP), Hôpitaux Universitaires Paris Ouest - Hôpitaux Universitaires Île de France Ouest (HUPO)-Assistance publique - Hôpitaux de Paris (AP-HP) (APHP)-Hôpitaux Universitaires Paris Ouest - Hôpitaux Universitaires Île de France Ouest (HUPO)-Assistance publique - Hôpitaux de Paris (AP-HP) (APHP)-Institut National de la Santé et de la Recherche Médicale (INSERM), and Hôpitaux Universitaires Paris Ouest - Hôpitaux Universitaires Île de France Ouest (HUPO)-Assistance publique - Hôpitaux de Paris (AP-HP) (APHP)-Hôpitaux Universitaires Paris Ouest - Hôpitaux Universitaires Île de France Ouest (HUPO)-Université Paris Descartes - Paris 5 (UPD5)

Subjects
chloride channel, Patch-Clamp Techniques, outer medullary collecting duct, [SDV]Life Sciences [q-bio], NPPB, CLCNKB, 2′-stilbene disulfonic acid disodium salt, MESH: Recombinant Proteins, ClC family, 4′-diisothiocyanato-2, MESH: Syndrome, MESH: Animals, ClC familly, ComputingMilieux_MISCELLANEOUS, ClC-K1, distal convoluted tubule, DCT, DPC, Hydrogen-Ion Concentration, Middle Aged, MESH: Infant, DIDS, Phenotype, MESH: Young Adult, MESH: HEK293 Cells, MESH: Kidney Tubules, Female, 5-nitro-2-(3-phenylpropylamino) benzoic acid, connecting tubule, OMCD, Adult, kidney, CNT, Bartter, [SDV.BC]Life Sciences [q-bio]/Cellular Biology, CLCNKB, ClC family, Bartter, 2-(phenylamino) benzoic acid, 4′-diisothiocyanato-2, 2′-stilbene disulfonic acid disodium salt, 5-nitro-2-(3-phenylpropylamino) benzoic acid, CCD, CNT, CTAL, Chloride channel, ClC, ClC-K, ClC-K1, DCT, DIDS, DPC, Kidney, NPPB, OMCD, Patch-clamp, connecting tubule, cortical collecting duct, cortical thick ascending limb, distal convoluted tubule, kidney chloride channel, outer medullary collecting duct, cortical collecting duct, MESH: Oocytes, Young Adult, Chloride Channels, CTAL, MESH: Xenopus laevis, ClC, MESH: Patch-Clamp Techniques, Humans, Point Mutation, CCD, MESH: Point Mutation, MESH: Humans, MESH: Chloride Channels, Bartter Syndrome, MESH: Male, cortical thick ascending limb, Mutation, Calcium, MESH: Sodium Potassium Chloride Symporter Inhibitors, kidney chloride channel, 2-(phenylamino) benzoic acid, Patch-clamp, ClC-K
Abstract

International audience; ClC-Kb, a member of the ClC family of Cl(-) channels/transporters, plays a major role in the absorption of NaCl in the distal nephron. CLCNKB mutations cause Bartter syndrome type 3, a hereditary renal salt-wasting tubulopathy. Here, we investigate the functional consequences of a Val to Met substitution at position 170 (V170M, α helix F), which was detected in eight patients displaying a mild phenotype. Conductance and surface expression were reduced by ~40-50 %. The regulation of channel activity by external H(+) and Ca(2+) is a characteristic property of ClC-Kb. Inhibition by external H(+) was dramatically altered, with pKH shifting from 7.6 to 6.0. Stimulation by external Ca(2+) on the other hand was no longer detectable at pH 7.4, but was still present at acidic pH values. Functionally, these regulatory modifications partly counterbalance the reduced surface expression by rendering V170M hyperactive. Pathogenic Met170 seems to interact with another methionine on α helix H (Met227) since diverse mutations at this site partly removed pH sensitivity alterations of V170M ClC-Kb. Exploring other disease-associated mutations, we found that a Pro to Leu substitution at position 124 (α helix D, Simon et al., Nat Genet 1997, 17:171-178) had functional consequences similar to those of V170M. In conclusion, we report here for the first time that ClC-Kb disease-causing mutations located around the selectivity filter can result in both reduced surface expression and hyperactivity in heterologous expression systems. This interplay must be considered when analyzing the mild phenotype of patients with type 3 Bartter syndrome.

Published
2014
Full Text
View/download PDF

18. The ClC-K2 Chloride Channel Is Critical for Salt Handling in the Distal Nephron

Author

Hennings, J. Christopher, primary, Andrini, Olga, additional, Picard, Nicolas, additional, Paulais, Marc, additional, Huebner, Antje K., additional, Cayuqueo, Irma Karen Lopez, additional, Bignon, Yohan, additional, Keck, Mathilde, additional, Cornière, Nicolas, additional, Böhm, David, additional, Jentsch, Thomas J., additional, Chambrey, Régine, additional, Teulon, Jacques, additional, Hübner, Christian A., additional, and Eladari, Dominique, additional

Published
2016
Full Text
View/download PDF

21. Renal Chloride Channels in Relation to Sodium Chloride Transport

Author

Teulon, Jacques, Planelles, Gabrielle, Sepúlveda, Francisco V., Andrini, Olga, Lourdel, Stéphane, and Paulais, Marc

Abstract

The many mechanisms governing NaCl absorption in the diverse parts of the renal tubule have been largely elucidated, although some of them, as neutral NaCl absorption across the cortical collecting duct or regulation through with-no-lysine (WNK) kinases have emerged only recently. Chloride channels, which are important players in these processes, at least in the distal nephron, are the focus of this review. Over the last 20-year period, experimental studies using molecular, electrophysiological, and physiological/functional approaches have deepened and renewed our views on chloride channels and their role in renal function. Two chloride channels of the ClC family, named as ClC-Ka and ClC-Kb in humans and ClC-K1 and ClC-K2 in other mammals, are preponderant and play complementary roles: ClC-K1/Ka is mainly involved in the building of the interstitial cortico-medullary concentration gradient, while ClC-K2/Kb participates in NaCl absorption in the thick ascending limb, distal convoluted tubule and the intercalated cells of the collecting duct. The two ClC-Ks might also be involved indirectly in proton secretion by type A intercalated cells. Other chloride channels in the kidneys include CFTR, TMEM16A, and probably volume-regulated LRRC8 chloride channels, whose function and molecular identity have not as yet been established. © 2019 American Physiological Society. Compr Physiol9:301-342, 2019.

Published
2019
Full Text
View/download PDF

22. CLCNKB mutations causing mild Bartter syndrome profoundly alter the pH and Ca2+ dependence of ClC-Kb channels

Author

Andrini, Olga, primary, Keck, Mathilde, additional, L’Hoste, Sébastien, additional, Briones, Rodolfo, additional, Mansour-Hendili, Lamisse, additional, Grand, Teddy, additional, Sepúlveda, Francisco V., additional, Blanchard, Anne, additional, Lourdel, Stéphane, additional, Vargas-Poussou, Rosa, additional, and Teulon, Jacques, additional

Published
2013
Full Text
View/download PDF

28. ClC-K chloride channels: emerging pathophysiology of Bartter syndrome type 3.

Author

Andrini, Olga, Keck, Mathilde, Briones, Rodolfo, Lourdel, Stéphane, Vargas-Poussou, Rosa, and Teulon, Jacques

Subjects
*BARTTER syndrome, *CHLORIDE channels, *PATHOLOGICAL physiology, *GENETIC mutation, *GENE expression
Abstract

The mutations in the CLCNKB gene encoding the ClC-Kb chloride channel are responsible for Bartter syndrome type 3, one of the four variants of Bartter syndrome in the genetically based nomenclature. All forms of Bartter syndrome are characterized by hypokalemia, metabolic alkalosis, and secondary hyperaldosteronism, but Bartter syndrome type 3 has the most heterogeneous presentation, extending from severe to very mild. A relatively large number of CLCNKB mutations have been reported, including gene deletions and nonsense or missense mutations. However, only 20 CLCNKB mutations have been functionally analyzed, due to technical difficulties regarding ClC-Kb functional expression in heterologous systems. This review provides an overview of recent progress in the functional consequences of CLCNKB mutations on ClC-Kb chloride channel activity. It has been observed that 1) all ClC-Kb mutants have an impaired expression at the membrane; and 2) a minority of the mutants combines reduced membrane expression with altered pH-dependent channel gating. Although further investigation is needed to fully characterize disease pathogenesis, Bartter syndrome type 3 probably belongs to the large family of conformational diseases, in which the mutations destabilize channel structure, inducing ClC-Kb retention in the endoplasmic reticulum and accelerated channel degradation. [ABSTRACT FROM AUTHOR]

Published
2015
Full Text
View/download PDF

29. Lithium interactions with Na+-coupled inorganic phosphate cotransporters: insights into the mechanism of sequential cation binding.

Author

Andrini, Olga, Meinild, Anne-Kristine, Ghezzi, Chiara, Murer, Heini, and Forster, Ian C.

Abstract

Type IIa/b Na+-coupled inorganic phosphate cotransporters (NaPi-IIa/b) are considered to be exclusively Na+ dependent. Here we show that Li+ can substitute for Na+ as a driving cation. We expressed NaPi-IIa/b in Xenopus laevis oocytes and performed two-electrode voltage-clamp electrophysiology and uptake assays to investigate the effect of external Li+ on their kinetics. Replacement of 50% external Na+ with Li+ reduced the maximum transport rate and the rate-limiting plateau of the Pi-induced current began at less hyperpolarizing potentials. Simultaneous electrophysiology and 22Na uptake on single oocytes revealed that Li+ ions can substitute for at least one of the three Na+ ions necessary for cotransport. Presteady-state assays indicated that Li+ ions alone interact with the empty carrier; however, the total charge displaced was 70% of that with Na+ alone, or when 50% of the Na+ was replaced by Li+. If Na + and Li+ were both present, the midpoint potential of the steady-state charge distribution was shifted towards depolarizing potentials. The charge movement in the presence of Li+ alone reflected the interaction of one Li+ ion, in contrast to 2 Na+ ions when only Na was present. We propose an ordered binding scheme for cotransport in which Li+ competes with Na+ to occupy the putative first cation interaction site, followed by the cooperative binding of one Na+ ion, one divalent Pi anion, and a third Na+ ion to complete the carrier loading. With Li+ bound, the kinetics of subsequent partial reactions were significantly altered. Kinetic simulations of this scheme support our experimental data. [ABSTRACT FROM AUTHOR]

Published
2012
Full Text
View/download PDF

30. The ClC-K2 Chloride Channel Is Critical for Salt Handling in the Distal Nephron.

Author

Hennings JC, Andrini O, Picard N, Paulais M, Huebner AK, Cayuqueo IK, Bignon Y, Keck M, Cornière N, Böhm D, Jentsch TJ, Chambrey R, Teulon J, Hübner CA, and Eladari D

Subjects
Animals, Diuretics pharmacology, Furosemide pharmacology, Mice, Mice, Knockout, Nephrons drug effects, Sodium Chloride Symporter Inhibitors pharmacology, Anion Transport Proteins physiology, Chloride Channels physiology, Nephrons metabolism, Sodium Chloride metabolism
Abstract

Chloride transport by the renal tubule is critical for blood pressure (BP), acid-base, and potassium homeostasis. Chloride uptake from the urinary fluid is mediated by various apical transporters, whereas basolateral chloride exit is thought to be mediated by ClC-Ka/K1 and ClC-Kb/K2, two chloride channels from the ClC family, or by KCl cotransporters from the SLC12 gene family. Nevertheless, the localization and role of ClC-K channels is not fully resolved. Because inactivating mutations in ClC-Kb/K2 cause Bartter syndrome, a disease that mimics the effects of the loop diuretic furosemide, ClC-Kb/K2 is assumed to have a critical role in salt handling by the thick ascending limb. To dissect the role of this channel in detail, we generated a mouse model with a targeted disruption of the murine ortholog ClC-K2. Mutant mice developed a Bartter syndrome phenotype, characterized by renal salt loss, marked hypokalemia, and metabolic alkalosis. Patch-clamp analysis of tubules isolated from knockout (KO) mice suggested that ClC-K2 is the main basolateral chloride channel in the thick ascending limb and in the aldosterone-sensitive distal nephron. Accordingly, ClC-K2 KO mice did not exhibit the natriuretic response to furosemide and exhibited a severely blunted response to thiazide. We conclude that ClC-Kb/K2 is critical for salt absorption not only by the thick ascending limb, but also by the distal convoluted tubule., (Copyright © 2016 by the American Society of Nephrology.)

Published
2017
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results