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Talbi K, Melk A. Not every organ ticks the same. Nat Rev Nephrol 2024:10.1038/s41581-024-00842-0. [PMID: 38658670 DOI: 10.1038/s41581-024-00842-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Affiliation(s)
- Khaoula Talbi
- Department of Pediatric Kidney, Liver and Metabolic Diseases, Hannover Medical School, Hannover, Germany
| | - Anette Melk
- Department of Pediatric Kidney, Liver and Metabolic Diseases, Hannover Medical School, Hannover, Germany.
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Kunzelmann K, Centeio R, Ousingsawat J, Talbi K, Seidler U, Schreiber R. SLC26A9 in airways and intestine: secretion or absorption? Channels (Austin) 2023; 17:2186434. [PMID: 36866602 PMCID: PMC9988340 DOI: 10.1080/19336950.2023.2186434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/04/2023] Open
Abstract
SLC26A9 is one out of 11 proteins that belong to the SLC26A family of anion transporters. Apart from expression in the gastrointestinal tract, SLC26A9 is also found in the respiratory system, in male tissues and in the skin. SLC26A9 has gained attention because of its modifier role in the gastrointestinal manifestation of cystic fibrosis (CF). SLC26A9 appears to have an impact on the extent of intestinal obstruction caused by meconium ileus. SLC26A9 supports duodenal bicarbonate secretion, but was assumed to provide a basal Cl- secretory pathway in airways. However, recent results show that basal airway Cl- secretion is due to cystic fibrosis conductance regulator (CFTR), while SLC26A9 may rather secrete HCO3-, thereby maintaining proper airway surface liquid (ASL) pH. Moreover, SLC26A9 does not secrete but probably supports reabsorption of fluid particularly in the alveolar space, which explains early death by neonatal distress in Slc26a9-knockout animals. While the novel SLC26A9 inhibitor S9-A13 helped to unmask the role of SLC26A9 in the airways, it also provided evidence for an additional role in acid secretion by gastric parietal cells. Here we discuss recent data on the function of SLC26A9 in airways and gut, and how S9-A13 may be useful in unraveling the physiological role of SLC26A9.
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Affiliation(s)
- Karl Kunzelmann
- Institut für Physiologie, Universität, Universitätsstraße 31, Regensburg, Germany
- CONTACT Karl Kunzelmann
| | - Raquel Centeio
- Institut für Physiologie, Universität, Universitätsstraße 31, Regensburg, Germany
| | - Jiraporn Ousingsawat
- Institut für Physiologie, Universität, Universitätsstraße 31, Regensburg, Germany
| | - Khaoula Talbi
- Institut für Physiologie, Universität, Universitätsstraße 31, Regensburg, Germany
| | - Ursula Seidler
- Department of Gastroenterology, Hannover Medical School, Hannover, Germany
| | - Rainer Schreiber
- Institut für Physiologie, Universität, Universitätsstraße 31, Regensburg, Germany
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Talbi K, Ousingsawat J, Centeio R, Schreiber R, Kunzelmann K. KCNE1 does not shift TMEM16A from a Ca 2+ dependent to a voltage dependent Cl - channel and is not expressed in renal proximal tubule. Pflugers Arch 2023:10.1007/s00424-023-02829-5. [PMID: 37442855 PMCID: PMC10359377 DOI: 10.1007/s00424-023-02829-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 05/02/2023] [Accepted: 06/08/2023] [Indexed: 07/15/2023]
Abstract
The TMEM16A (ANO1) Cl- channel is activated by Ca2+ in a voltage-dependent manner. It is broadly expressed and was shown to be also present in renal proximal tubule (RPT). KCNQ1 is an entirely different K+ selective channel that forms the cardiac IKS potassium channel together with its ß-subunit KCNE1. Surprisingly, KCNE1 has been claimed to interact with TMEM16A, and to be required for activation of TMEM16A in mouse RPT. Interaction with KCNE1 was reported to switch TMEM16A from a Ca22+-dependent to a voltage-dependent ion channel. Here we demonstrate that KCNE1 is not expressed in mouse RPT. TMEM16A expressed in RPT is activated by angiotensin II and ATP in a KCNE1-independent manner. Coexpression of KCNE1 does not change TMEM16A to a voltage gated Cl- channel and Ca2+-dependent regulation of TMEM16A is fully maintained in the presence of KCNE1. While overexpressed KCNE1 slightly affects Ca2+-dependent regulation of TMEM16A, the data provide no evidence for KCNE1 being an auxiliary functional subunit for TMEM16A.
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Affiliation(s)
- Khaoula Talbi
- Physiological Institute, University of Regensburg, University street 31, D-93053, Regensburg, Germany
| | - Jiraporn Ousingsawat
- Physiological Institute, University of Regensburg, University street 31, D-93053, Regensburg, Germany
| | - Raquel Centeio
- Physiological Institute, University of Regensburg, University street 31, D-93053, Regensburg, Germany
| | - Rainer Schreiber
- Physiological Institute, University of Regensburg, University street 31, D-93053, Regensburg, Germany
| | - Karl Kunzelmann
- Physiological Institute, University of Regensburg, University street 31, D-93053, Regensburg, Germany.
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Schreiber R, Talbi K, Ousingsawat J, Kunzelmann K. A TMEM16J variant leads to dysregulated cytosolic calcium which may lead to renal disease. FASEB J 2023; 37:e22683. [PMID: 36520003 DOI: 10.1096/fj.202200968r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 11/05/2022] [Accepted: 11/21/2022] [Indexed: 12/23/2022]
Abstract
SIGIRR (single immunoglobulin IL-1 related receptor), PKP3 (plakophilin 3), and TMEM16J (anoctamin 9), a putative calcium-activated ion channel and phospholipid scramblase, control the immune response and the extent of inflammation. Variants of SIGIRR/PKP3/TMEM16J lead to severe inflammatory diseases such as pneumonia, enterocolitis, and kidney graft rejection. Meta-analysis of genome-wide association studies identified TMEM16J-T604A as a promotor for chronic kidney disease (CKD), but the disease mechanism and function of TMEM16J remain unknown. Here, we demonstrate TMEM16J as a calcium-activated calcium-permeable channel, which is expressed in the endoplasmic reticulum (ER). TMEM16J controls the intracellular distribution of calcium, and inhibits intracellular receptor-mediated Ca2+ signals and Ca2+ -dependent activation of ion channels, but augments transcription and release of pro-inflammatory cytokines. Renal epithelial cells expressing the variant TMEM16J-T604A show enhanced calcium signals when compared to cells expressing wt-TMEM16J, and demonstrate spontaneous transcription and release of cytokines. This study identifies TMEM16J as an important regulator of intracellular Ca2+ signals, ion channel activity, and cytokine release. TMEM16J may therefore affect immune response in renal tissue and immune cells.
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Affiliation(s)
- Rainer Schreiber
- Institut für Physiologie, Universität Regensburg, Regensburg, Germany
| | - Khaoula Talbi
- Institut für Physiologie, Universität Regensburg, Regensburg, Germany
| | | | - Karl Kunzelmann
- Institut für Physiologie, Universität Regensburg, Regensburg, Germany
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Lin J, Gettings SM, Talbi K, Schreiber R, Taggart MJ, Preller M, Kunzelmann K, Althaus M, Gray MA. Pharmacological inhibitors of the cystic fibrosis transmembrane conductance regulator exert off-target effects on epithelial cation channels. Pflugers Arch 2023; 475:167-179. [PMID: 36205782 PMCID: PMC9849171 DOI: 10.1007/s00424-022-02758-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 09/28/2022] [Accepted: 10/03/2022] [Indexed: 02/01/2023]
Abstract
The cystic fibrosis transmembrane conductance regulator (CFTR) anion channel and the epithelial Na+ channel (ENaC) play essential roles in transepithelial ion and fluid transport in numerous epithelial tissues. Inhibitors of both channels have been important tools for defining their physiological role in vitro. However, two commonly used CFTR inhibitors, CFTRinh-172 and GlyH-101, also inhibit non-CFTR anion channels, indicating they are not CFTR specific. However, the potential off-target effects of these inhibitors on epithelial cation channels has to date not been addressed. Here, we show that both CFTR blockers, at concentrations routinely employed by many researchers, caused a significant inhibition of store-operated calcium entry (SOCE) that was time-dependent, poorly reversible and independent of CFTR. Patch clamp experiments showed that both CFTRinh-172 and GlyH-101 caused a significant block of Orai1-mediated whole cell currents, establishing that they likely reduce SOCE via modulation of this Ca2+ release-activated Ca2+ (CRAC) channel. In addition to off-target effects on calcium channels, both inhibitors significantly reduced human αβγ-ENaC-mediated currents after heterologous expression in Xenopus oocytes, but had differential effects on δβγ-ENaC function. Molecular docking identified two putative binding sites in the extracellular domain of ENaC for both CFTR blockers. Together, our results indicate that caution is needed when using these two CFTR inhibitors to dissect the role of CFTR, and potentially ENaC, in physiological processes.
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Affiliation(s)
- JinHeng Lin
- grid.1006.70000 0001 0462 7212Biosciences Institute, Newcastle University, Newcastle upon Tyne, NE2 4HH UK ,grid.4991.50000 0004 1936 8948Present Address: Department of Pharmacology, University of Oxford, Oxford, OX1 3QT UK
| | - Sean M. Gettings
- grid.1006.70000 0001 0462 7212School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU UK
| | - Khaoula Talbi
- grid.7727.50000 0001 2190 5763Physiological Institute, University of Regensburg, 93053 Regensburg, Germany
| | - Rainer Schreiber
- grid.7727.50000 0001 2190 5763Physiological Institute, University of Regensburg, 93053 Regensburg, Germany
| | - Michael J. Taggart
- grid.1006.70000 0001 0462 7212Biosciences Institute, Newcastle University, Newcastle upon Tyne, NE2 4HH UK
| | - Matthias Preller
- grid.425058.e0000 0004 0473 3519Department of Natural Sciences/Institute for Functional Gene Analytics, Structural Biology Group, Bonn-Rhein-Sieg University of Applied Sciences, 53359 Rheinbach, Germany
| | - Karl Kunzelmann
- grid.7727.50000 0001 2190 5763Physiological Institute, University of Regensburg, 93053 Regensburg, Germany
| | - Mike Althaus
- grid.1006.70000 0001 0462 7212School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU UK ,grid.425058.e0000 0004 0473 3519Present Address: Department of Natural Sciences /Institute for Functional Gene Analytics, Ion Transport Physiology Group, Bonn-Rhein-Sieg University of Applied Sciences, 53359 Rheinbach, Germany
| | - Michael A. Gray
- grid.1006.70000 0001 0462 7212Biosciences Institute, Newcastle University, Newcastle upon Tyne, NE2 4HH UK
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Jo S, Centeio R, Park J, Ousingsawat J, Jeon DK, Talbi K, Schreiber R, Ryu K, Kahlenberg K, Somoza V, Delpiano L, Gray MA, Amaral MD, Railean V, Beekman JM, Rodenburg LW, Namkung W, Kunzelmann K. The SLC26A9 inhibitor S9-A13 provides no evidence for a role of SLC26A9 in airway chloride secretion but suggests a contribution to regulation of ASL pH and gastric proton secretion. FASEB J 2022; 36:e22534. [PMID: 36183361 DOI: 10.1096/fj.202200313rr] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 08/11/2022] [Accepted: 08/24/2022] [Indexed: 11/11/2022]
Abstract
The solute carrier 26 family member A9 (SLC26A9) is an epithelial anion transporter that is assumed to contribute to airway chloride secretion and surface hydration. Whether SLC26A9 or CFTR is responsible for airway Cl- transport under basal conditions is still unclear, due to the lack of a specific inhibitor for SLC26A9. In the present study, we report a novel potent and specific inhibitor for SLC26A9, identified by screening of a drug-like molecule library and subsequent chemical modifications. The most potent compound S9-A13 inhibited SLC26A9 with an IC50 of 90.9 ± 13.4 nM. S9-A13 did not inhibit other members of the SLC26 family and had no effects on Cl- channels such as CFTR, TMEM16A, or VRAC. S9-A13 inhibited SLC26A9 Cl- currents in cells that lack expression of CFTR. It also inhibited proton secretion by HGT-1 human gastric cells. In contrast, S9-A13 had minimal effects on ion transport in human airway epithelia and mouse trachea, despite clear expression of SLC26A9 in the apical membrane of ciliated cells. In both tissues, basal and stimulated Cl- secretion was due to CFTR, while acidification of airway surface liquid by S9-A13 suggests a role of SLC26A9 for airway bicarbonate secretion.
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Affiliation(s)
- Sungwoo Jo
- College of Pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon, South Korea
| | - Raquel Centeio
- Physiological Institute, University of Regensburg, Regensburg, Germany
| | - Jinhong Park
- College of Pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon, South Korea
| | | | - Dong-Kyu Jeon
- College of Pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon, South Korea
| | - Khaoula Talbi
- Leibniz Institute for Food Systems Biology at the Technical University of Munich, Freising, Germany
| | - Rainer Schreiber
- Physiological Institute, University of Regensburg, Regensburg, Germany
| | - Kunhi Ryu
- College of Pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon, South Korea
| | - Kristin Kahlenberg
- Leibniz Institute for Food Systems Biology at the Technical University of Munich, Freising, Germany
| | - Veronika Somoza
- Leibniz Institute for Food Systems Biology at the Technical University of Munich, Freising, Germany
| | - Livia Delpiano
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Michael A Gray
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Margarida D Amaral
- BioISI-Biosystems & Integrative Sciences Institute, Faculty of Sciences, University of Lisboa, Lisbon, Portugal
| | - Violeta Railean
- BioISI-Biosystems & Integrative Sciences Institute, Faculty of Sciences, University of Lisboa, Lisbon, Portugal
| | - Jeffrey M Beekman
- Regenerative Medicine Utrecht, University Medical Center, Utrecht University, Utrecht, Netherlands
| | - Lisa W Rodenburg
- Regenerative Medicine Utrecht, University Medical Center, Utrecht University, Utrecht, Netherlands
| | - Wan Namkung
- College of Pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon, South Korea
| | - Karl Kunzelmann
- Physiological Institute, University of Regensburg, Regensburg, Germany
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Ousingsawat J, Centeio R, Cabrita I, Talbi K, Zimmer O, Graf M, Göpferich A, Schreiber R, Kunzelmann K. Airway Delivery of Hydrogel-Encapsulated Niclosamide for the Treatment of Inflammatory Airway Disease. Int J Mol Sci 2022; 23:ijms23031085. [PMID: 35163010 PMCID: PMC8835663 DOI: 10.3390/ijms23031085] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 01/03/2022] [Accepted: 01/17/2022] [Indexed: 11/16/2022] Open
Abstract
Repurposing of the anthelminthic drug niclosamide was proposed as an effective treatment for inflammatory airway diseases such as asthma, cystic fibrosis, and chronic obstructive pulmonary disease. Niclosamide may also be effective for the treatment of viral respiratory infections, such as SARS-CoV-2, respiratory syncytial virus, and influenza. While systemic application of niclosamide may lead to unwanted side effects, local administration via aerosol may circumvent these problems, particularly when the drug is encapsulated into small polyethylene glycol (PEG) hydrospheres. In the present study, we examined whether PEG-encapsulated niclosamide inhibits the production of mucus and affects the pro-inflammatory mediator CLCA1 in mouse airways in vivo, while effects on mucociliary clearance were assessed in excised mouse tracheas. The potential of encapsulated niclosamide to inhibit TMEM16A whole-cell Cl- currents and intracellular Ca2+ signalling was assessed in airway epithelial cells in vitro. We achieved encapsulation of niclosamide in PEG-microspheres and PEG-nanospheres (Niclo-spheres). When applied to asthmatic mice via intratracheal instillation, Niclo-spheres strongly attenuated overproduction of mucus, inhibited secretion of the major proinflammatory mediator CLCA1, and improved mucociliary clearance in tracheas ex vivo. These effects were comparable for niclosamide encapsulated in PEG-nanospheres and PEG-microspheres. Niclo-spheres inhibited the Ca2+ activated Cl- channel TMEM16A and attenuated mucus production in CFBE and Calu-3 human airway epithelial cells. Both inhibitory effects were explained by a pronounced inhibition of intracellular Ca2+ signals. The data indicate that poorly dissolvable compounds such as niclosamide can be encapsulated in PEG-microspheres/nanospheres and deposited locally on the airway epithelium as encapsulated drugs, which may be advantageous over systemic application.
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Affiliation(s)
- Jiraporn Ousingsawat
- Physiological Institute, University of Regensburg, University Street 31, 93040 Regensburg, Germany; (J.O.); (R.C.); (I.C.); (K.T.); (R.S.)
| | - Raquel Centeio
- Physiological Institute, University of Regensburg, University Street 31, 93040 Regensburg, Germany; (J.O.); (R.C.); (I.C.); (K.T.); (R.S.)
| | - Inês Cabrita
- Physiological Institute, University of Regensburg, University Street 31, 93040 Regensburg, Germany; (J.O.); (R.C.); (I.C.); (K.T.); (R.S.)
| | - Khaoula Talbi
- Physiological Institute, University of Regensburg, University Street 31, 93040 Regensburg, Germany; (J.O.); (R.C.); (I.C.); (K.T.); (R.S.)
| | - Oliver Zimmer
- Department of Pharmaceutical Technology, University of Regensburg, 93040 Regensburg, Germany; (O.Z.); (M.G.); (A.G.)
| | - Moritz Graf
- Department of Pharmaceutical Technology, University of Regensburg, 93040 Regensburg, Germany; (O.Z.); (M.G.); (A.G.)
| | - Achim Göpferich
- Department of Pharmaceutical Technology, University of Regensburg, 93040 Regensburg, Germany; (O.Z.); (M.G.); (A.G.)
| | - Rainer Schreiber
- Physiological Institute, University of Regensburg, University Street 31, 93040 Regensburg, Germany; (J.O.); (R.C.); (I.C.); (K.T.); (R.S.)
| | - Karl Kunzelmann
- Physiological Institute, University of Regensburg, University Street 31, 93040 Regensburg, Germany; (J.O.); (R.C.); (I.C.); (K.T.); (R.S.)
- Correspondence: ; Tel.: +49-(0)941-943-4302; Fax: +49-(0)941-943-4315
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Bouguerra G, Talbi K, Trabelsi N, Chaouachi D, Boudriga I, Abbès S, Menif S. Enhanced Eryptosis in Glucose-6-Phosphate Dehydrogenase Deficiency. Cell Physiol Biochem 2021; 55:761-772. [PMID: 34894207 DOI: 10.33594/000000474] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/15/2021] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND/AIMS Defects in the Glucose-6-Phosphate Dehydrogenase (G6PD) enzyme enhance cellular oxidative damage, thus impairing erythrocytes and radically shortening their lifespan. We aimed to study programmed erythrocyte cell death in G6PD-deficient patients, describe the molecular genetics basis of G6PD and investigate phenotype-genotype correlations. METHODS We explored eryptosis using the annexin V-binding assay, taken as an indicator of PS exposure at the erythrocyte surface. We assessed reactive oxygen species (ROS) production, intracellular calcium concentrations and ceramide formation at the cell surface. Prior to and following treatments, cells were analyzed by flow cytometry. Finally, we explored G6PD gene mutations through PCR-Sanger sequencing. RESULTS Before stimulation, PS-exposing erythrocytes were significantly higher in G6PD-deficient patients than in healthy volunteers. This was paralleled by a significant increase in reactive oxygen species production, suggesting that oxidative stress is the main trigger of PS exposure in G6PD-deficient erythrocytes. Five previously described mutations were detected in our patients. Two genotypes correlated with a significantly higher percentage of PS-exposing cells. CONCLUSION Our study uncovers a novel effect detected in G6PD-deficient erythrocytes which is cell membrane scrambling with PS translocation to the erythrocyte surface. Our findings shed a light on the mechanisms of premature erythrocyte clearance in G6PD deficiency.
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Affiliation(s)
- Ghada Bouguerra
- Université de Tunis El Manar, Faculté de Médecine de Tunis, Tunis, Tunisie, .,Université de Tunis El Manar, Laboratoire d'Hématologie Moléculaire et Cellulaire, Institut Pasteur de Tunis, Tunis, Tunisie
| | - Khaoula Talbi
- Université de Tunis El Manar, Laboratoire d'Hématologie Moléculaire et Cellulaire, Institut Pasteur de Tunis, Tunis, Tunisie.,Université de Tunis El Manar, Faculté des Sciences de Tunis, Tunis, Tunisie
| | - Nawel Trabelsi
- Université de Tunis El Manar, Laboratoire d'Hématologie Moléculaire et Cellulaire, Institut Pasteur de Tunis, Tunis, Tunisie.,Université de Tunis El Manar, Faculté des Sciences de Tunis, Tunis, Tunisie
| | - Dorra Chaouachi
- Université de Tunis El Manar, Laboratoire d'Hématologie Moléculaire et Cellulaire, Institut Pasteur de Tunis, Tunis, Tunisie
| | - Imen Boudriga
- Université de Tunis El Manar, Laboratoire d'Hématologie Moléculaire et Cellulaire, Institut Pasteur de Tunis, Tunis, Tunisie
| | - Salem Abbès
- Université de Tunis El Manar, Faculté de Médecine de Tunis, Tunis, Tunisie.,Université de Tunis El Manar, Laboratoire d'Hématologie Moléculaire et Cellulaire, Institut Pasteur de Tunis, Tunis, Tunisie
| | - Samia Menif
- Université de Tunis El Manar, Faculté de Médecine de Tunis, Tunis, Tunisie.,Université de Tunis El Manar, Laboratoire d'Hématologie Moléculaire et Cellulaire, Institut Pasteur de Tunis, Tunis, Tunisie
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Talbi K, Cabrita I, Kraus A, Hofmann S, Skoczynski K, Kunzelmann K, Buchholz B, Schreiber R. The chloride channel CFTR is not required for cyst growth in an ADPKD mouse model. FASEB J 2021; 35:e21897. [PMID: 34473378 DOI: 10.1096/fj.202100843r] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 08/09/2021] [Accepted: 08/18/2021] [Indexed: 01/01/2023]
Abstract
Autosomal dominant polycystic kidney disease (ADPKD) is characterized by the development of bilateral renal cysts which enlarge continuously, leading to compression of adjacent intact nephrons. The growing cysts lead to a progressive decline in renal function. Cyst growth is driven by enhanced cell proliferation and chloride secretion into the cyst lumen. Chloride secretion is believed to occur mainly by the cAMP-activated cystic fibrosis transmembrane conductance regulator (CFTR), with some contribution by the calcium-activated chloride channel TMEM16A. However, our previous work suggested TMEM16A as a major factor for renal cyst formation. The contribution of CFTR to cyst formation has never been demonstrated in an adult ADPKD mouse model. We used mice with an inducible tubule-specific Pkd1 knockout, which consistently develop polycystic kidneys upon deletion of Pkd1. Cellular properties, ion currents, and cyst development in these mice were compared with that of mice carrying a co-deletion of Pkd1 and Cftr. Knockout of Cftr did not reveal any significant impact on cyst formation in the ADPKD mouse model. Furthermore, knockout of Cftr did not attenuate the largely augmented cell proliferation observed in Pkd1 knockout kidneys. Patch clamp analysis on primary renal epithelial cells lacking expression of Pkd1 indicated an only marginal contribution of CFTR to whole cell Cl- currents, which were clearly dominated by calcium-activated TMEM16A currents. In conclusion, CFTR does not essentially contribute to renal cyst formation in mice caused by deletion of Pkd1. Enhanced cell proliferation and chloride secretion is caused primarily by upregulation of the calcium-activated chloride channel TMEM16A.
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Affiliation(s)
- Khaoula Talbi
- Department of Physiology, University of Regensburg, Regensburg, Germany
| | - Inês Cabrita
- Department of Physiology, University of Regensburg, Regensburg, Germany
| | - Andre Kraus
- Department of Nephrology and Hypertension, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany
| | - Sascha Hofmann
- Department of Physiology, University of Regensburg, Regensburg, Germany
| | - Kathrin Skoczynski
- Department of Nephrology and Hypertension, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany
| | - Karl Kunzelmann
- Department of Physiology, University of Regensburg, Regensburg, Germany
| | - Bjoern Buchholz
- Department of Nephrology and Hypertension, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany
| | - Rainer Schreiber
- Department of Physiology, University of Regensburg, Regensburg, Germany
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Cabrita I, Talbi K, Kunzelmann K, Schreiber R. Loss of PKD1 and PKD2 share common effects on intracellular Ca 2+ signaling. Cell Calcium 2021; 97:102413. [PMID: 33915319 DOI: 10.1016/j.ceca.2021.102413] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 04/17/2021] [Accepted: 04/18/2021] [Indexed: 12/21/2022]
Abstract
In polycystic kidney disease (PKD) multiple bilateral renal cysts gradually enlarge causing a decline in renal function. Transepithelial chloride secretion through cystic fibrosis transmembrane conductance regulator (CFTR) and TMEM16A (anoctamin 1) drive cyst enlargement. We demonstrated recently that a loss of PKD1 increases expression and function of TMEM16A in murine kidneys and in mouse M1 collecting duct cells. The data demonstrated that TMEM16A contributes essentially to cyst growth by upregulating intracellular Ca2+ signaling. Enhanced expression of TMEM16A and Ca2+ signaling increased both cell proliferation and fluid secretion, which suggested inhibition of TMEM16A as a novel therapy in ADPKD. About 15 % of all ADPKD cases are caused by mutations in PKD2. To analyze the effects of loss of function of PKD2 on Ca2+ signaling, we knocked-down Pkd2 in mouse primary renal epithelial cells in the present study, using viral transfection of shRNA. Unlike in Pkd1-/- cells, knockdown of PKD2 lowered basal Ca2+ and augmented store-operated Ca2+ entry, which was both independent of TMEM16A. However, disease causing purinergic Ca2+ store release was enhanced, similar to that observed in Pkd1-/- renal epithelial cells. The present data suggest pharmacological inhibition of TMEM16A as a treatment in ADPKD caused by mutations in both PKD1 and PKD2.
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Affiliation(s)
- Ines Cabrita
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
| | - Khaoula Talbi
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
| | - Karl Kunzelmann
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany.
| | - Rainer Schreiber
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
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Centeio R, Cabrita I, Benedetto R, Talbi K, Ousingsawat J, Schreiber R, Sullivan JK, Kunzelmann K. Pharmacological Inhibition and Activation of the Ca 2+ Activated Cl - Channel TMEM16A. Int J Mol Sci 2020; 21:ijms21072557. [PMID: 32272686 PMCID: PMC7177308 DOI: 10.3390/ijms21072557] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 03/26/2020] [Accepted: 04/02/2020] [Indexed: 12/14/2022] Open
Abstract
TMEM16A is a Ca2+ activated Cl− channel with important functions in airways, intestine, and other epithelial organs. Activation of TMEM16A is proposed as a therapy in cystic fibrosis (CF) to reinstall airway Cl− secretion and to enhance airway surface liquid (ASL). This CFTR-agnostic approach is thought to improve mucociliary clearance and lung function in CF. This could indeed improve ASL, however, mucus release and airway contraction may also be induced by activators of TMEM16A, particularly in inflamed airways of patients with asthma, COPD, or CF. Currently, both activators and inhibitors of TMEM16A are developed and examined in different types of tissues. Here we compare activation and inhibition of endogenous and overexpressed TMEM16A and analyze potential off-target effects. The three well-known blockers benzbromarone, niclosamide, and Ani9 inhibited both TMEM16A and ATP-induced Ca2+ increase by variable degrees, depending on the cell type. Niclosamide, while blocking Ca2+ activated TMEM16A, also induced a subtle but significant Ca2+ store release and inhibited store-operated Ca2+ influx. Niclosamide, benzbromarone and Ani9 also affected TMEM16F whole cell currents, indicating limited specificity for these inhibitors. The compounds Eact, cinnamaldehyde, and melittin, as well as the phosphatidylinositol diC8-PIP2 are the reported activators of TMEM16A. However, the compounds were unable to activate endogenous TMEM16A in HT29 colonic epithelial cells. In contrast, TMEM16A overexpressed in HEK293 cells was potently stimulated by these activators. We speculate that overexpressed TMEM16A might have a better accessibility to intracellular Ca2+, which causes spontaneous activity even at basal intracellular Ca2+ concentrations. Small molecules may therefore potentiate pre-stimulated TMEM16A currents, but may otherwise fail to activate silent endogenous TMEM16A.
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Affiliation(s)
- Raquel Centeio
- Physiological Institute, University of Regensburg, D-93053 Regensburg, Germany; (R.C.); (I.C.); (R.B.); (K.T.); (J.O.); (R.S.)
| | - Inês Cabrita
- Physiological Institute, University of Regensburg, D-93053 Regensburg, Germany; (R.C.); (I.C.); (R.B.); (K.T.); (J.O.); (R.S.)
| | - Roberta Benedetto
- Physiological Institute, University of Regensburg, D-93053 Regensburg, Germany; (R.C.); (I.C.); (R.B.); (K.T.); (J.O.); (R.S.)
| | - Khaoula Talbi
- Physiological Institute, University of Regensburg, D-93053 Regensburg, Germany; (R.C.); (I.C.); (R.B.); (K.T.); (J.O.); (R.S.)
| | - Jiraporn Ousingsawat
- Physiological Institute, University of Regensburg, D-93053 Regensburg, Germany; (R.C.); (I.C.); (R.B.); (K.T.); (J.O.); (R.S.)
| | - Rainer Schreiber
- Physiological Institute, University of Regensburg, D-93053 Regensburg, Germany; (R.C.); (I.C.); (R.B.); (K.T.); (J.O.); (R.S.)
| | | | - Karl Kunzelmann
- Physiological Institute, University of Regensburg, D-93053 Regensburg, Germany; (R.C.); (I.C.); (R.B.); (K.T.); (J.O.); (R.S.)
- * Correspondence: ; Tel.: +49-(0)941-943-4302; Fax: +49-(0)941-943-4315
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Bouakkaz R, Talbi K, Ouazzazi M, Khelili Y, Salhi F. EFFECT OF ROTATION RATES ON THE LAMINAR FLOW AND HEAT TRANSFER PAST A CIRCULAR CYLINDER. Braz J Chem Eng 2015. [DOI: 10.1590/0104-6632.20150322s00002539] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
| | - K. Talbi
- Université Constantine 1, Algérie
| | | | | | - F. Salhi
- Université Mouloud Mammeri, Algérie
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Abstract
Abstract
Vapour extraction (VAPEX) has recently emerged as an attractive alternative to thermal recovery techniques for the huge resources of heavy oils and bitumen available in Canada, the USA and Venezuela. The current version of VAPEX relies on the injection of light hydrocarbon gases for reducing the oil viscosity. The economic viability of this process is very sensitive to the cost of injected gases in relation to the selling price of the produced oil. One attractive option for reducing the cost of injected gases appears to be the use of CO2 as a major component of the injected solvent. This modification will utilize mixtures of CO2 and propane as the solvent instead of the currently popular mixtures of methane and propane. Since CO2 is significantly more soluble in heavy oils than methane, it is likely that such mixtures will provide greater reduction in viscosity compared to equivalent mixtures of methane and propane.
In this work, methane-propane and CO2-propane were investigated as solvents for the VAPEX process for in situ recovery of heavy oil and bitumen. Twelve laboratory experiments were performed with two types of oil [4,500 mPas and 18,600 mPas at 294.15 K (21 ºC)]. These tests were performed in a partially-scaled physical model at different operating pressures ranging from 1,469.3 kPa (200 psig) to 4,227.2 kPa (600 psig) and were designed to compare the performance of methane-based solvents with that of CO2-based solvents. The main conclusion from this study is that the CO2-based VAPEX process can be more cost effective and environmentally friendly than the conventional VAPEX process.
Introduction
With the decline of conventional oil reserves, a major thrust of oil producers throughout the world is on the exploitation of heavy oil and bitumen reserves. The magnitude of these resources worldwide is about six trillion barrels of oil-in-place; six times total conventional reserves(1), and is likely to be the future source of energy. The majority of these resources are located in Venezuela, Canada and the United States(2). In most cases, conventional recovery methods cannot be implemented in heavy oil and bitumen reservoirs due to the high viscosity(3) of the oil. The high viscosity rules out primary production in many reservoirs, and even in lower viscosity reservoirs, the primary recovery is less than 10% of the original oil-in-place (OOIP)(4, 5).
The Steam-Assisted Gravity Drainage (SAGD)(6, 7) process has gained tremendous popularity in the industry for its usefulness in producing high viscosity heavy oil and bitumen. In this process, the heat is injected into the reservoir by injecting steam through a horizontal well; steam condenses at the boundary of a growing steam saturated zone and heats the oil. Consequently, the viscosity is lowered and the hot oil drains down under the influence of gravity into another horizontal well located near the bottom of the formation. Even though thermal methods are successful in exploiting these resources, they often suffer from low energy efficiency due partly to heat losses to the cap and base rock.
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