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Schreiber R, Ousingsawat J, Kunzelmann K. The anoctamins: Structure and function. Cell Calcium 2024; 120:102885. [PMID: 38642428 DOI: 10.1016/j.ceca.2024.102885] [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] [Received: 02/21/2024] [Revised: 04/03/2024] [Accepted: 04/04/2024] [Indexed: 04/22/2024]
Abstract
When activated by increase in intracellular Ca2+, anoctamins (TMEM16 proteins) operate as phospholipid scramblases and as ion channels. Anoctamin 1 (ANO1) is the Ca2+-activated epithelial anion-selective channel that is coexpressed together with the abundant scramblase ANO6 and additional intracellular anoctamins. In salivary and pancreatic glands, ANO1 is tightly packed in the apical membrane and secretes Cl-. Epithelia of airways and gut use cystic fibrosis transmembrane conductance regulator (CFTR) as an apical Cl- exit pathway while ANO1 supports Cl- secretion mainly by facilitating activation of luminal CFTR and basolateral K+ channels. Under healthy conditions ANO1 modulates intracellular Ca2+ signals by tethering the endoplasmic reticulum, and except of glands its direct secretory contribution as Cl- channel might be small, compared to CFTR. In the kidneys ANO1 supports proximal tubular acid secretion and protein reabsorption and probably helps to excrete HCO3-in the collecting duct epithelium. However, under pathological conditions as in polycystic kidney disease, ANO1 is strongly upregulated and may cause enhanced proliferation and cyst growth. Under pathological condition, ANO1 and ANO6 are upregulated and operate as secretory channel/phospholipid scramblases, partly by supporting Ca2+-dependent processes. Much less is known about the role of other epithelial anoctamins whose potential functions are discussed in this review.
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Affiliation(s)
- Rainer Schreiber
- 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
| | - Karl Kunzelmann
- Physiological Institute, University of Regensburg, University street 31, D-93053 Regensburg, Germany.
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Kunzelmann K, Ousingsawat J, Schreiber R. VSI: The anoctamins: Structure and function: "Intracellular" anoctamins. Cell Calcium 2024; 120:102888. [PMID: 38657371 DOI: 10.1016/j.ceca.2024.102888] [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] [Received: 02/20/2024] [Revised: 04/15/2024] [Accepted: 04/16/2024] [Indexed: 04/26/2024]
Abstract
Plasma membrane localized anoctamin 1, 2 and 6 (TMEM16A, B, F) have been examined in great detail with respect to structure and function, but much less is known about the other seven intracellular members of this exciting family of proteins. This is probably due to their limited accessibility in intracellular membranous compartments, such as the endoplasmic reticulum (ER) or endosomes. However, these so-called intracellular anoctamins are also found in the plasma membrane (PM) which adds to the confusion regarding their cellular role. Probably all intracellular anoctamins except of ANO8 operate as intracellular phospholipid (PL) scramblases, allowing for Ca2+-activated, passive transport of phospholipids like phosphatidylserine between both membrane leaflets. Probably all of them also conduct ions, which is probably part of their physiological function. In this brief overview, we summarize key findings on the biological functions of ANO3, 4, 5, 7, 8, 9 and 10 (TMEM16C, D, E, G, H, J, K) that are gradually coming to light. Compartmentalized regulation of intracellular Ca2+ signals, tethering of the ER to specific PM contact sites, and control of intracellular vesicular trafficking appear to be some of the functions of intracellular anoctamins, while loss of function and abnormal expression are the cause for various diseases.
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Affiliation(s)
- Karl Kunzelmann
- 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
| | - Rainer Schreiber
- Physiological Institute, University of Regensburg, University street 31, D-93053, Regensburg, Germany
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Ousingsawat J, Centeio R, Schreiber R, Kunzelmann K. Niclosamide, but not ivermectin, inhibits anoctamin 1 and 6 and attenuates inflammation of the respiratory tract. Pflugers Arch 2024; 476:211-227. [PMID: 37979051 DOI: 10.1007/s00424-023-02878-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [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] [Received: 08/22/2023] [Revised: 10/28/2023] [Accepted: 11/01/2023] [Indexed: 11/19/2023]
Abstract
Inflammatory airway diseases like cystic fibrosis, asthma and COVID-19 are characterized by high levels of pulmonary cytokines. Two well-established antiparasitic drugs, niclosamide and ivermectin, are intensively discussed for the treatment of viral inflammatory airway infections. Here, we examined these repurposed drugs with respect to their anti-inflammatory effects in airways in vivo and in vitro. Niclosamide reduced mucus content, eosinophilic infiltration and cell death in asthmatic mouse lungs in vivo and inhibited release of interleukins in the two differentiated airway epithelial cell lines CFBE and BCi-NS1.1 in vitro. Cytokine release was also inhibited by the knockdown of the Ca2+-activated Cl- channel anoctamin 1 (ANO1, TMEM16A) and the phospholipid scramblase anoctamin 6 (ANO6, TMEM16F), which have previously been shown to affect intracellular Ca2+ levels near the plasma membrane and to facilitate exocytosis. At concentrations around 200 nM, niclosamide inhibited inflammation, lowered intracellular Ca2+, acidified cytosolic pH and blocked activation of ANO1 and ANO6. It is suggested that niclosamide brings about its anti-inflammatory effects at least in part by inhibiting ANO1 and ANO6, and by lowering intracellular Ca2+ levels. In contrast to niclosamide, 1 µM ivermectin did not exert any of the effects described for niclosamide. The present data suggest niclosamide as an effective anti-inflammatory treatment in CF, asthma, and COVID-19, in addition to its previously reported antiviral effects. It has an advantageous concentration-response relationship and is known to be well tolerated.
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Affiliation(s)
- Jiraporn Ousingsawat
- Physiological Institute, University of Regensburg, Germany University Street 31, 93053, Regensburg, Germany
| | - Raquel Centeio
- Physiological Institute, University of Regensburg, Germany University Street 31, 93053, Regensburg, Germany
| | - Rainer Schreiber
- Physiological Institute, University of Regensburg, Germany University Street 31, 93053, Regensburg, Germany
| | - Karl Kunzelmann
- Physiological Institute, University of Regensburg, Germany University Street 31, 93053, Regensburg, Germany.
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Ousingsawat J, Centeio R, Reyne N, McCarron A, Cmielewski P, Schreiber R, diStefano G, Römermann D, Seidler U, Donnelley M, Kunzelmann K. Inhibition of mucus secretion by niclosamide and benzbromarone in airways and intestine. Sci Rep 2024; 14:1464. [PMID: 38233410 PMCID: PMC10794189 DOI: 10.1038/s41598-024-51397-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Accepted: 01/04/2024] [Indexed: 01/19/2024] Open
Abstract
The Ca2+ activated Cl- channel TMEM16A (anoctamin 1; ANO1) is expressed in secretory epithelial cells of airways and intestine. Previous studies provided evidence for a role of ANO1 in mucus secretion. In the present study we investigated the effects of the two ANO1-inhibitors niclosamide (Niclo) and benzbromarone (Benz) in vitro and in vivo in mouse models for cystic fibrosis (CF) and asthma. In human CF airway epithelial cells (CFBE), Ca2+ increase and activation of ANO1 by adenosine triphosphate (ATP) or ionomycin was strongly inhibited by 200 nM Niclo and 1 µM Benz. In asthmatic mice airway mucus secretion was inhibited by intratracheal instillation of Niclo or Benz. In homozygous F508del-cftr mice, intestinal mucus secretion and infiltration by CD45-positive cells was inhibited by intraperitoneal injection of Niclo (13 mg/kg/day for 7 days). In homozygous F508del-cftr rats intestinal mucus secretion was inhibited by oral application of Benz (5 mg/kg/day for 60 days). Taken together, well tolerated therapeutic concentrations of niclosamide and benzbromarone corresponding to plasma levels of treated patients, inhibit ANO1 and intracellular Ca2+ signals and may therefore be useful in inhibiting mucus hypersecretion and mucus obstruction in airways and intestine of patients suffering from asthma and CF, respectively.
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Affiliation(s)
- Jiraporn Ousingsawat
- Physiological Institute, University of Regensburg, University Street 31, 93053, Regensburg, Germany
| | - Raquel Centeio
- Physiological Institute, University of Regensburg, University Street 31, 93053, Regensburg, Germany
| | - Nicole Reyne
- Robinson Research Institute and Adelaide Medical School, University of Adelaide, Adelaide, SA, Australia
| | - Alexandra McCarron
- Robinson Research Institute and Adelaide Medical School, University of Adelaide, Adelaide, SA, Australia
| | - Patricia Cmielewski
- Robinson Research Institute and Adelaide Medical School, University of Adelaide, Adelaide, SA, Australia
| | - Rainer Schreiber
- Physiological Institute, University of Regensburg, University Street 31, 93053, Regensburg, Germany
| | - Gabriella diStefano
- Department of Gastroenterology, Hannover Medical School, 30625, Hannover, Germany
| | - Dorothee Römermann
- Department of Gastroenterology, Hannover Medical School, 30625, Hannover, Germany
| | - Ursula Seidler
- Department of Gastroenterology, Hannover Medical School, 30625, Hannover, Germany
| | - Martin Donnelley
- Robinson Research Institute and Adelaide Medical School, University of Adelaide, Adelaide, SA, Australia
| | - Karl Kunzelmann
- Physiological Institute, University of Regensburg, University Street 31, 93053, Regensburg, 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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Kunzelmann K, Ousingsawat J, Kraus A, Park JH, Marquardt T, Schreiber R, Buchholz B. Pathogenic Relationships in Cystic Fibrosis and Renal Diseases: CFTR, SLC26A9 and Anoctamins. Int J Mol Sci 2023; 24:13278. [PMID: 37686084 PMCID: PMC10487509 DOI: 10.3390/ijms241713278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 07/31/2023] [Accepted: 08/22/2023] [Indexed: 09/10/2023] Open
Abstract
The Cl--transporting proteins CFTR, SLC26A9, and anoctamin (ANO1; ANO6) appear to have more in common than initially suspected, as they all participate in the pathogenic process and clinical outcomes of airway and renal diseases. In the present review, we will therefore concentrate on recent findings concerning electrolyte transport in the airways and kidneys, and the role of CFTR, SLC26A9, and the anoctamins ANO1 and ANO6. Special emphasis will be placed on cystic fibrosis and asthma, as well as renal alkalosis and polycystic kidney disease. In essence, we will summarize recent evidence indicating that CFTR is the only relevant secretory Cl- channel in airways under basal (nonstimulated) conditions and after stimulation by secretagogues. Information is provided on the expressions of ANO1 and ANO6, which are important for the correct expression and function of CFTR. In addition, there is evidence that the Cl- transporter SLC26A9 expressed in the airways may have a reabsorptive rather than a Cl--secretory function. In the renal collecting ducts, bicarbonate secretion occurs through a synergistic action of CFTR and the Cl-/HCO3- transporter SLC26A4 (pendrin), which is probably supported by ANO1. Finally, in autosomal dominant polycystic kidney disease (ADPKD), the secretory function of CFTR in renal cyst formation may have been overestimated, whereas ANO1 and ANO6 have now been shown to be crucial in ADPKD and therefore represent new pharmacological targets for the treatment of polycystic kidney disease.
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Affiliation(s)
- Karl Kunzelmann
- Physiological Institute, University of Regensburg, University Street 31, 93053 Regensburg, Germany; (J.O.); (R.S.)
| | - Jiraporn Ousingsawat
- Physiological Institute, University of Regensburg, University Street 31, 93053 Regensburg, Germany; (J.O.); (R.S.)
| | - Andre Kraus
- Department of Nephrology and Hypertension, Friedrich Alexander University Erlangen Nuremberg, 91054 Erlangen, Germany; (A.K.); (B.B.)
| | - Julien H. Park
- Department of Pediatrics, University Hospital Münster, 48149 Münster, Germany; (J.H.P.); (T.M.)
| | - Thorsten Marquardt
- Department of Pediatrics, University Hospital Münster, 48149 Münster, Germany; (J.H.P.); (T.M.)
| | - Rainer Schreiber
- Physiological Institute, University of Regensburg, University Street 31, 93053 Regensburg, Germany; (J.O.); (R.S.)
| | - Björn Buchholz
- Department of Nephrology and Hypertension, Friedrich Alexander University Erlangen Nuremberg, 91054 Erlangen, Germany; (A.K.); (B.B.)
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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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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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10
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Ousingsawat J, Centeio R, Schreiber R, Kunzelmann K. Expression of SLC26A9 in Airways and Its Potential Role in Asthma. Int J Mol Sci 2022; 23:ijms23062998. [PMID: 35328418 PMCID: PMC8950296 DOI: 10.3390/ijms23062998] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 03/05/2022] [Accepted: 03/07/2022] [Indexed: 02/05/2023] Open
Abstract
SLC26A9 is an epithelial anion transporter with a poorly defined function in airways. It is assumed to contribute to airway chloride secretion and airway surface hydration. However, immunohistochemistry showing precise localization of SLC26A9 in airways is missing. Some studies report localization near tight junctions, which is difficult to reconcile with a chloride secretory function of SLC26A9. We therefore performed immunocytochemistry of SLC26A9 in sections of human and porcine lungs. Obvious apical localization of SLC26A9 was detected in human and porcine superficial airway epithelia, whereas submucosal glands did not express SLC26A9. The anion transporter was located exclusively in ciliated epithelial cells. Highly differentiated BCi-NS1 human airway epithelial cells grown on permeable supports also expressed SLC26A9 in the apical membrane of ciliated epithelial cells. BCi-NS1 cells expressed the major Cl− transporting proteins CFTR, TMEM16A and SLC26A9 in about equal proportions and produced short-circuit currents activated by increases in intracellular cAMP or Ca2+. Both CFTR and SLC26A9 contribute to basal chloride currents in non-stimulated BCi-NS1 airway epithelia, with CFTR being the dominating Cl− conductance. In wtCFTR-expressing CFBE human airway epithelial cells, SLC26A9 was partially located in the plasma membrane, whereas CFBE cells expressing F508del-CFTR showed exclusive cytosolic localization of SLC26A9. Membrane localization of SLC26A9 and basal chloride currents were augmented by interleukin 13 in wild-type CFTR-expressing cells, but not in cells expressing the most common disease-causing mutant F508del-CFTR. The data suggest an upregulation of SLC26A9-dependent chloride secretion in asthma, but not in the presence of F508del-CFTR.
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Affiliation(s)
| | | | | | - Karl Kunzelmann
- Correspondence: ; Tel.: +49-(0)941-943-4302; Fax: +49-(0)941-943-4315
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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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Ousingsawat J, Schreiber R, Gulbins E, Kamler M, Kunzelmann K. P. aeruginosa Induced Lipid Peroxidation Causes Ferroptotic Cell Death in Airways. Cell Physiol Biochem 2021; 55:590-604. [PMID: 34637202 DOI: 10.33594/000000437] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [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: 10/02/2021] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND/AIMS Oxidative stress and infections by Pseudomonas aeruginosa (P. aeruginosa) are prominent in lungs of patients suffering from cystic fibrosis (CF). METHODS The present study examines effects of P. aeruginosa on lipid peroxidation in human and mouse lungs, and cell death induced by P. aeruginosa in human airway epithelial cells. The role of the Ca2+ activated Cl- channel TMEM16A, the phospholipid scramblase TMEM16F, and the CFTR Cl- channel for ferroptotic cell death is examined. RESULTS Lipid peroxidation was detected in human CF lungs, which correlated with bacterial infection. In vivo inoculation with P. aeruginosa or Staphylococcus aureus (S. aureus) induced lipid peroxidation in lungs of mice lacking expression of CFTR, and in lungs of wild type animals. Incubation of CFBE human airway epithelial cells with P. aeruginosa induced an increase in reactive oxygen species (ROS), causing lipid peroxidation and cell death independent of expression of wt-CFTR or F508del-CFTR. Knockdown of TMEM16A attenuated P. aeruginosa induced cell death. Antioxidants such as coenzyme Q10 and idebenone as well as the inhibitor of ferroptosis, ferrostatin-1, inhibited P. aeruginosa-induced cell death. CFBE cells expressing wtCFTR, but not F508del-CFTR, activated a basal Cl- conductance upon exposure to P. aeruginosa, which was caused by an increase in intracellular basal Ca2+ concentrations and activation of Ca2+-dependent adenylate cyclase. CONCLUSION The data suggest an intrinsic pro-inflammatory phenotype in CF epithelial cells, while ferroptosis is observed in both non-CF and CF epithelial cells upon infection with P. aeruginosa. CF cells fail to activate fluid secretion in response to infection with P. aeruginosa. The use of antioxidants and inhibitors of ferroptosis is proposed as a treatment of pneumonia caused by infection with P. aeruginosa.
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Affiliation(s)
| | - Rainer Schreiber
- Institut für Physiologie, Universität Regensburg, Regensburg, Germany
| | - Erich Gulbins
- Institute of Molecular Biology, University of Duisburg-Essen, Medical School Essen, Essen, Germany
| | - Markus Kamler
- Department of Thoracic and Cardiovascular Surgery, Division of Thoracic Transplantation, University Hospital Essen, Essen, Germany
| | - Karl Kunzelmann
- Institut für Physiologie, Universität Regensburg, Regensburg, Germany,
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Cabrita I, Benedetto R, Wanitchakool P, Lerias J, Centeio R, Ousingsawat J, Schreiber R, Kunzelmann K. TMEM16A Mediates Mucus Production in Human Airway Epithelial Cells. Am J Respir Cell Mol Biol 2021; 64:50-58. [PMID: 33026825 DOI: 10.1165/rcmb.2019-0442oc] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
TMEM16A is a Ca2+-activated chloride channel that was shown to enhance production and secretion of mucus in inflamed airways. It is, however, not clear whether TMEM16A directly supports mucus production, or whether mucin and TMEM16A are upregulated independently during inflammatory airway diseases such as asthma and cystic fibrosis (CF). We examined this question using BCi-NS1 cells, a human airway basal cell line that maintains multipotent differentiation capacity, and the two human airway epithelial cell lines, Calu-3 and CFBE. The data demonstrate that exposure of airway epithelial cells to IL-8 and IL-13, two cytokines known to be enhanced in CF and asthma, respectively, leads to an increase in mucus production. Expression of MUC5AC was fully dependent on expression of TMEM16A, as shown by siRNA knockdown of TMEM16A. In addition, different inhibitors of TMEM16A attenuated IL-13-induced mucus production. Interestingly, in CFBE cells expressing F508 delCFTR, IL-13 was unable to upregulate membrane expression of TMEM16A or Ca2+-activated whole cell currents. The regulator of TMEM16A, CLCA1, strongly augmented both Ca2+- and cAMP-activated Cl- currents in cells expressing wtCFTR but failed to augment membrane expression of TMEM16A in F508 delCFTR-expressing CFBE cells. The data confirm the functional relationship between CFTR and TMEM16A and suggest an impaired upregulation of TMEM16A by IL-13 or CLCA1 in cells expressing the most frequent CF-causing mutation F508 delCFTR.
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Affiliation(s)
- Inês Cabrita
- Physiological Institute, University of Regensburg, Regensburg, Germany
| | - Roberta Benedetto
- Physiological Institute, University of Regensburg, Regensburg, Germany
| | | | - Joana Lerias
- Physiological Institute, University of Regensburg, Regensburg, Germany
| | - Raquel Centeio
- Physiological Institute, University of Regensburg, Regensburg, Germany
| | | | - Rainer Schreiber
- Physiological Institute, University of Regensburg, Regensburg, Germany
| | - Karl Kunzelmann
- Physiological Institute, University of Regensburg, Regensburg, Germany
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Centeio R, Ousingsawat J, Schreiber R, Kunzelmann K. Ca 2+ Dependence of Volume-Regulated VRAC/LRRC8 and TMEM16A Cl - Channels. Front Cell Dev Biol 2020; 8:596879. [PMID: 33335902 PMCID: PMC7736618 DOI: 10.3389/fcell.2020.596879] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 11/04/2020] [Indexed: 12/31/2022] Open
Abstract
All vertebrate cells activate Cl- currents (ICl ,swell) when swollen by hypotonic bath solution. The volume-regulated anion channel VRAC has now been identified as LRRC8/SWELL1. However, apart from VRAC, the Ca2+-activated Cl- channel (CaCC) TMEM16A and the phospholipid scramblase and ion channel TMEM16F were suggested to contribute to cell swelling-activated whole-cell currents. Cell swelling was shown to induce Ca2+ release from the endoplasmic reticulum and to cause subsequent Ca2+ influx. It is suggested that TMEM16A/F support intracellular Ca2+ signaling and thus Ca2+-dependent activation of VRAC. In the present study, we tried to clarify the contribution of TMEM16A to ICl ,swell. In HEK293 cells coexpressing LRRC8A and LRRC8C, we found that activation of ICl ,swell by hypotonic bath solution (Hypo; 200 mosm/l) was Ca2+ dependent. TMEM16A augmented the activation of LRRC8A/C by enhancing swelling-induced local intracellular Ca2+ concentrations. In HT29 cells, knockdown of endogenous TMEM16A attenuated ICl ,swell and changed time-independent swelling-activated currents to VRAC-typical time-dependent currents. Activation of ICl ,swell by Hypo was attenuated by blocking receptors for inositol trisphosphate and ryanodine (IP3R; RyR), as well as by inhibiting Ca2+ influx. The data suggest that TMEM16A contributes directly to ICl ,swell as it is activated through swelling-induced Ca2+ increase. As activation of VRAC is shown to be Ca2+-dependent, TMEM16A augments VRAC currents by facilitating Hypo-induced Ca2+ increase in submembraneous signaling compartments by means of ER tethering.
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Affiliation(s)
| | | | | | - Karl Kunzelmann
- Physiological Institute, University of Regensburg, Regensburg, Germany
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Park JH, Ousingsawat J, Cabrita I, Bettels RE, Große-Onnebrink J, Schmalstieg C, Biskup S, Reunert J, Rust S, Schreiber R, Kunzelmann K, Marquardt T. TMEM16A deficiency: a potentially fatal neonatal disease resulting from impaired chloride currents. J Med Genet 2020; 58:247-253. [PMID: 32487539 DOI: 10.1136/jmedgenet-2020-106978] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 04/14/2020] [Accepted: 04/18/2020] [Indexed: 12/13/2022]
Abstract
INTRODUCTION TMEM16A is a calcium-activated chloride channel expressed in various secretory epithelia. Two siblings presented in early infancy with reduced intestinal peristalsis and recurrent episodes of haemorrhagic diarrhoea. In one of them, the episodes were characterised by hepatic pneumatosis with gas bubbles in the portal vein similar to necrotising enterocolitis of the newborn. METHODS Exome sequencing identified a homozygous truncating pathogenic variant in ANO1. Expression analysis was performed using reverse transcription PCR, western blot and immunohistochemistry. Electrophysiological and cell biological studies were employed to characterise the effects on ion transport both in patient respiratory epithelial cells and in transfected HEK293 cells. RESULTS The identified variant led to TMEM16A dysfunction, which resulted in abolished calcium-activated Cl- currents. Secondarily, CFTR function is affected due to the close interplay between both channels without inducing cystic fibrosis (CF). CONCLUSION TMEM16A deficiency is a potentially fatal disorder caused by abolished calcium-activated Cl- currents in secretory epithelia. Secondary impairment of CFTR function did not cause a CF phenotyp, which may have implications for CF treatment.
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Affiliation(s)
- Julien H Park
- Department of Paediatrics, University Hospital Münster, Münster, Nordrhein-Westfalen, Germany
| | | | - Inês Cabrita
- Department of Physiology, University of Regensburg, Regensburg, Bayern, Germany
| | - Ruth E Bettels
- Department of Paediatrics, University Hospital Münster, Münster, Nordrhein-Westfalen, Germany
| | - Jörg Große-Onnebrink
- Department of Paediatrics, University Hospital Münster, Münster, Nordrhein-Westfalen, Germany
| | - Christian Schmalstieg
- Department of Paediatrics, University Hospital Münster, Münster, Nordrhein-Westfalen, Germany
| | | | - Janine Reunert
- Department of Paediatrics, University Hospital Münster, Münster, Nordrhein-Westfalen, Germany
| | - Stephan Rust
- Department of Paediatrics, University Hospital Münster, Münster, Nordrhein-Westfalen, Germany
| | - Rainer Schreiber
- Department of Physiology, University of Regensburg, Regensburg, Bayern, Germany
| | - Karl Kunzelmann
- Department of Physiology, University of Regensburg, Regensburg, Bayern, Germany
| | - Thorsten Marquardt
- Department of Paediatrics, University Hospital Münster, Münster, Nordrhein-Westfalen, Germany
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Pinto MC, Schreiber R, Lerias J, Ousingsawat J, Duarte A, Amaral M, Kunzelmann K. Regulation of TMEM16A by CK2 and Its Role in Cellular Proliferation. Cells 2020; 9:cells9051138. [PMID: 32380794 PMCID: PMC7291285 DOI: 10.3390/cells9051138] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 05/01/2020] [Accepted: 05/02/2020] [Indexed: 12/25/2022] Open
Abstract
Casein kinase 2 (CK2) is a highly ubiquitous and conserved serine/threonine kinase that forms a tetramer consisting of a catalytic subunit (CK2α) and a regulatory subunit (CK2β). Despite being ubiquitous, CK2 is commonly found at higher expression levels in cancer cells, where it inhibits apoptosis, and supports cell migration and proliferation. The Ca2+-activated chloride channel TMEM16A shows similar effects in cancer cells: TMEM16A increases cell proliferation and migration and is highly expressed in squamous cell carcinoma of the head and neck (HNSCC) as well as other malignant tumors. A microscopy-based high-throughput screening was performed to identify proteins that regulate TMEM16A. Within this screen, CK2 was found to be required for proper membrane expression of TMEM16A. small interfering (si) RNA-knockdown of CK2 reduced plasma membrane expression of TMEM16A and inhibited TMEM16A whole cell currents in (cystic fibrosis bronchial epithelial) CFBE airway epithelial cells and in the head and neck cancer cell lines Cal33 and BHY. Inhibitors of CK2, such as TBB and the preclinical compound CX4549 (silmitasertib), also blocked membrane expression of TMEM16A and Ca2+-activated whole cell currents. siRNA-knockout of CK2 and its pharmacological inhibition, as well as knockdown or inhibition of TMEM16A by either niclosamide or Ani9, attenuated cell proliferation. Simultaneous inhibition of CK2 and TMEM16A strongly potentiated inhibition of cell proliferation. Although membrane expression of TMEM16A is reduced by inhibition of CK2, our data suggest that the antiproliferative effects by inhibition of CK2 are mostly independent of TMEM16A. Simultaneous inhibition of TMEM16A by niclosamide and inhibition of CK2 by silmitasertib was additive with respect to blocking cell proliferation, while cytotoxicity was reduced when compared to solely blockade of CK2. Therefore, parallel blockade TMEM16A by niclosamide may assist with anticancer therapy by silmitasertib.
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Affiliation(s)
- Madalena C. Pinto
- Faculty of Sciences, University of Lisbon, BioISI—Biosystems & Integrative Sciences Institute, Campo Grande, 1749-016 Lisbon, Portugal; (M.C.P.); (J.L.); (A.D.); (M.A.)
| | - Rainer Schreiber
- Physiological Institute, University of Regensburg, University Street 31, D-93053 Regensburg, Germany; (R.S.); (J.O.)
| | - Joana Lerias
- Faculty of Sciences, University of Lisbon, BioISI—Biosystems & Integrative Sciences Institute, Campo Grande, 1749-016 Lisbon, Portugal; (M.C.P.); (J.L.); (A.D.); (M.A.)
| | - Jiraporn Ousingsawat
- Physiological Institute, University of Regensburg, University Street 31, D-93053 Regensburg, Germany; (R.S.); (J.O.)
| | - Aires Duarte
- Faculty of Sciences, University of Lisbon, BioISI—Biosystems & Integrative Sciences Institute, Campo Grande, 1749-016 Lisbon, Portugal; (M.C.P.); (J.L.); (A.D.); (M.A.)
| | - Margarida Amaral
- Faculty of Sciences, University of Lisbon, BioISI—Biosystems & Integrative Sciences Institute, Campo Grande, 1749-016 Lisbon, Portugal; (M.C.P.); (J.L.); (A.D.); (M.A.)
| | - Karl Kunzelmann
- Physiological Institute, University of Regensburg, University Street 31, D-93053 Regensburg, Germany; (R.S.); (J.O.)
- Correspondence: ; Tel.: +49-941-943-4302; Fax: +49-941-943-4315
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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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Ousingsawat J, Schreiber R, Kunzelmann K. TMEM16F/Anoctamin 6 in Ferroptotic Cell Death. Cancers (Basel) 2019; 11:E625. [PMID: 31060306 PMCID: PMC6562394 DOI: 10.3390/cancers11050625] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 05/01/2019] [Accepted: 05/03/2019] [Indexed: 12/21/2022] Open
Abstract
Ca2+ activated Cl- channels (TMEM16A; ANO1) support cell proliferation and cancer growth. Expression of TMEM16A is strongly enhanced in different types of malignomas. In contrast, TMEM16F (ANO6) operates as a Ca2+ activated chloride/nonselective ion channel and scrambles membrane phospholipids to expose phosphatidylserine at the cell surface. Both phospholipid scrambling and cell swelling induced through activation of nonselective ion currents appear to destabilize the plasma membrane thereby causing cell death. There is growing evidence that activation of TMEM16F contributes to various forms of regulated cell death. In the present study, we demonstrate that ferroptotic cell death, occurring during peroxidation of plasma membrane phospholipids activates TMEM16F. Ferroptosis was induced by erastin, an inhibitor of the cystine-glutamate antiporter and RSL3, an inhibitor of glutathione peroxidase 4 (GPX4). Cell death was largely reduced in the intestinal epithelium, and in peritoneal macrophages isolated from mice with tissue-specific knockout of TMEM16F. We show that TMEM16F is activated during erastin and RSL3-induced ferroptosis. In contrast, inhibition of ferroptosis by ferrostatin-1 and by inhibitors of TMEM16F block TMEM16F currents and inhibit cell death. We conclude that activation of TMEM16F is a crucial component during ferroptotic cell death, a finding that may be useful to induce cell death in cancer cells.
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Affiliation(s)
- Jiraporn Ousingsawat
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany.
| | - Rainer Schreiber
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany.
| | - Karl Kunzelmann
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany.
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Benedetto R, Ousingsawat J, Cabrita I, Pinto M, Lérias JR, Wanitchakool P, Schreiber R, Kunzelmann K. Plasma membrane-localized TMEM16 proteins are indispensable for expression of CFTR. J Mol Med (Berl) 2019; 97:711-722. [PMID: 30915480 DOI: 10.1007/s00109-019-01770-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [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] [Received: 10/18/2018] [Revised: 02/22/2019] [Accepted: 03/05/2019] [Indexed: 10/27/2022]
Abstract
The cystic fibrosis transmembrane conductance regulator (CFTR) is the secretory chloride channel in epithelial tissues that has a central role in cystic fibrosis (CF) lung and gastrointestinal disease. A recent publication demonstrates a close association between CFTR and TMEM16A, the calcium-activated chloride channel. Thus, no CFTR chloride currents could be detected in airways and large intestine from mice lacking epithelial expression of TMEM16A. Here, we demonstrate that another plasma membrane-localized TMEM16 paralogue, TMEM16F, can compensate for the lack of TMEM16A. Using TMEM16 knockout mice, human lymphocytes, and a number of human cell lines with endogenous protein expression or heterologous expression, we demonstrate that CFTR can only function in the presence of either TMEM16A or TMEM16F. Double knockout of intestinal epithelial TMEM16A/F expression did not produce offsprings, suggesting a lethal phenotype in utero. Plasma membrane-localized TMEM16A or TMEM16F is required for exocytosis and expression of CFTR in the plasma membrane. TMEM16A/F proteins may therefore have an impact on disease severity in CF. KEY MESSAGES: • Cystic fibrosis is caused by the defective Cl- channel cystic fibrosis transmembrane conductance regulator (CFTR). • A close relationship exists between CFTR and the calcium-activated chloride channels TMEM16A/TMEM16F. • In conditional airway and intestinal knockout mice, lymphocytes from Scott disease patients and in overexpressing cells, CFTR is not functional in the absence of TMEM16A and TMEM16F. • TMEM16A and TMEM16F support membrane exocytosis and are essential for plasma membrane insertion of CFTR.
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Affiliation(s)
- Roberta Benedetto
- 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
| | - Inês Cabrita
- Physiological Institute, University of Regensburg, University Street 31, D-93053, Regensburg, Germany
| | - Madalena Pinto
- Physiological Institute, University of Regensburg, University Street 31, D-93053, Regensburg, Germany
| | - Joana R Lérias
- Physiological Institute, University of Regensburg, University Street 31, D-93053, Regensburg, Germany
| | - Podchanart Wanitchakool
- 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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Kunzelmann K, Ousingsawat J, Cabrita I, Doušová T, Bähr A, Janda M, Schreiber R, Benedetto R. TMEM16A in Cystic Fibrosis: Activating or Inhibiting? Front Pharmacol 2019; 10:3. [PMID: 30761000 PMCID: PMC6362895 DOI: 10.3389/fphar.2019.00003] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Accepted: 01/04/2019] [Indexed: 12/26/2022] Open
Abstract
The inflammatory airway disease cystic fibrosis (CF) is characterized by airway obstruction due to mucus hypersecretion, airway plugging, and bronchoconstriction. The cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel is dysfunctional in CF, leading to defects in epithelial transport. Although CF pathogenesis is still disputed, activation of alternative Cl- channels is assumed to improve lung function in CF. Two suitable non-CFTR Cl- channels are present in the airway epithelium, the Ca2+ activated channel TMEM16A and SLC26A9. Activation of these channels is thought to be feasible to improve hydration of the airway mucus and to increase mucociliary clearance. Interestingly, both channels are upregulated during inflammatory lung disease. They are assumed to support fluid secretion, necessary to hydrate excess mucus and to maintain mucus clearance. During inflammation, however, TMEM16A is upregulated particularly in mucus producing cells, with only little expression in ciliated cells. Recently it was shown that knockout of TMEM16A in ciliated cells strongly compromises Cl- conductance and attenuated mucus secretion, but does not lead to a CF-like lung disease and airway plugging. Along this line, activation of TMEM16A by denufosol, a stable purinergic ligand, failed to demonstrate any benefit to CF patients in earlier studies. It rather induced adverse effects such as cough. A number of studies suggest that TMEM16A is essential for mucus secretion and possibly also for mucus production. Evidence is now provided for a crucial role of TMEM16A in fusion of mucus-filled granules with the apical plasma membrane and cellular exocytosis. This is probably due to local Ca2+ signals facilitated by TMEM16A. Taken together, TMEM16A supports fluid secretion by ciliated airway epithelial cells, but also maintains excessive mucus secretion during inflammatory airway disease. Because TMEM16A also supports airway smooth muscle contraction, inhibition rather than activation of TMEM16A might be the appropriate treatment for CF lung disease, asthma and COPD. As a number of FDA-approved and well-tolerated drugs have been shown to inhibit TMEM16A, evaluation in clinical trials appears timely.
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Affiliation(s)
- Karl Kunzelmann
- Institut für Physiologie, Universität Regensburg, Regensburg, Germany
| | | | - Inês Cabrita
- Institut für Physiologie, Universität Regensburg, Regensburg, Germany
| | - Tereza Doušová
- Department of Pediatrics, Second Faculty of Medicine, University Hospital Motol, Charles University in Prague, Prague, Czechia
| | - Andrea Bähr
- Institute of Molecular Animal Breeding and Biotechnology, Ludwig-Maximilians-Universität München, Munich, Germany
- Innere Medizin I, Klinikum Rechts der Isar der TU München, München, Germany
| | - Melanie Janda
- Institute of Molecular Animal Breeding and Biotechnology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Rainer Schreiber
- Institut für Physiologie, Universität Regensburg, Regensburg, Germany
| | - Roberta Benedetto
- Institut für Physiologie, Universität Regensburg, Regensburg, Germany
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Schreiber R, Buchholz B, Kraus A, Schley G, Scholz J, Ousingsawat J, Kunzelmann K. Lipid Peroxidation Drives Renal Cyst Growth In Vitro through Activation of TMEM16A. J Am Soc Nephrol 2019; 30:228-242. [PMID: 30606785 DOI: 10.1681/asn.2018010039] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Accepted: 11/19/2018] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Transepithelial chloride- secretion, through the chloride channels cystic fibrosis transmembrane conductance regulator (CFTR) and TMEM16A (anoctamin 1), drives cyst enlargement in polycystic kidney disease (PKD). Polycystic kidneys are hypoxic, and oxidative stress activates TMEM16A. However, mechanisms for channel activation in PKD remain obscure. METHODS Using tissue samples from patients with autosomal dominant PKD, embryonic kidney cultures, and an MDCK in vitro cyst model, we assessed peroxidation of plasma membrane phospholipids in human and mouse polycystic kidneys. We also used electrophysiologic Ussing chamber and patch clamp experiments to analyze activation of TMEM16A and growth of renal cysts. RESULTS Peroxidation of phospholipids in human and mouse kidneys as well as MDCK cysts in vitro is probably due to enhanced levels of reactive oxygen species. Lipid peroxidation correlated with increased cyst volume as shown in renal cultures and MDCK cysts in three-dimensional cultures. Reactive oxygen species and lipid peroxidation strongly activated TMEM16A, leading to depletion of calcium ion stores and store-operated calcium influx. Activation of TMEM16A- and CFTR-dependent chloride secretion strongly augmented cyst growth. Exposure to scavengers of reactive oxygen species, such as glutathione, coenzyme Q10, or idebenone (a synthetic coenzyme Q10 homolog), as well as inhibition of oxidative lipid damage by ferrostatin-1 largely reduced activation of TMEM16A. Inhibition of TMEM16A reduced proliferation and fluid secretion in vitro. CONCLUSIONS These findings indicate that activation of TMEM16A by lipid peroxidation drives growth of renal cysts. We propose direct inhibition of TMEM16A or inhibition of lipid peroxidation as potentially powerful therapeutic approaches to delay cyst development in PKD.
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Affiliation(s)
- Rainer Schreiber
- Department of Physiology, University of Regensburg, Regensburg, Germany; and
| | - Björn Buchholz
- Department of Nephrology and Hypertension, Friedrich-Alexander University of Erlangen-Nürnberg, Erlangen, Germany
| | - Andre Kraus
- Department of Nephrology and Hypertension, Friedrich-Alexander University of Erlangen-Nürnberg, Erlangen, Germany
| | - Gunnar Schley
- Department of Nephrology and Hypertension, Friedrich-Alexander University of Erlangen-Nürnberg, Erlangen, Germany
| | - Julia Scholz
- Department of Nephrology and Hypertension, Friedrich-Alexander University of Erlangen-Nürnberg, Erlangen, Germany
| | | | - Karl Kunzelmann
- Department of Physiology, University of Regensburg, Regensburg, Germany; and
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Schenk LK, Ousingsawat J, Skryabin BV, Schreiber R, Pavenstädt H, Kunzelmann K. Regulation and Function of TMEM16F in Renal Podocytes. Int J Mol Sci 2018; 19:ijms19061798. [PMID: 29912162 PMCID: PMC6032267 DOI: 10.3390/ijms19061798] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2018] [Revised: 06/12/2018] [Accepted: 06/14/2018] [Indexed: 12/13/2022] Open
Abstract
The Ca2+-activated phospholipid scramblase and ion channel TMEM16F is expressed in podocytes of renal glomeruli. Podocytes are specialized cells that form interdigitating foot processes as an essential component of the glomerular filter. These cells, which participate in generation of the primary urine, are often affected during primary glomerular diseases, such as glomerulonephritis and secondary hypertensive or diabetic nephropathy, which always leads to proteinuria. Because the function of podocytes is known to be controlled by intracellular Ca2+ signaling, it is important to know about the role of Ca2+-activated TMEM16F in these cells. To that end, we generated an inducible TMEM16F knockdown in the podocyte cell line AB8, and produced a conditional mouse model with knockout of TMEM16F in podocytes and renal epithelial cells of the nephron. We found that knockdown of TMEM16F did not produce proteinuria or any obvious phenotypic changes. Knockdown of TMEM16F affected cell death of tubular epithelial cells but not of glomerular podocytes when analyzed in TUNEL assays. Surprisingly, and in contrast to other cell types, TMEM16F did not control intracellular Ca2+ signaling and was not responsible for Ca2+-activated whole cell currents in podocytes. TMEM16F levels in podocytes were enhanced after inhibition of the endolysosomal pathway and after treatment with angiotensin II. Renal knockout of TMEM16F did not compromise renal morphology and serum electrolytes. Taken together, in contrast to other cell types, such as platelets, bone cells, and immune cells, TMEM16F shows little effect on basal properties of podocytes and does not appear to be essential for renal function.
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Affiliation(s)
- Laura K Schenk
- Department of Nephrology, Hypertension and Rheumatology, University Hospital Muenster, 48149 Muenster, Germany.
| | - Jiraporn Ousingsawat
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany.
| | - Boris V Skryabin
- Transgenic Animal and Genetic Engineering Models (TRAM), Department of Medicine, Westfälischen, Wilhelms⁻Universität Münster, 48149 Münster, Germany.
| | - Rainer Schreiber
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany.
| | - Hermann Pavenstädt
- Department of Nephrology, Hypertension and Rheumatology, University Hospital Muenster, 48149 Muenster, Germany.
| | - Karl Kunzelmann
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany.
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Schreiber R, Ousingsawat J, Wanitchakool P, Sirianant L, Benedetto R, Reiss K, Kunzelmann K. Regulation of TMEM16A/ANO1 and TMEM16F/ANO6 ion currents and phospholipid scrambling by Ca 2+ and plasma membrane lipid. J Physiol 2018; 596:217-229. [PMID: 29134661 PMCID: PMC5767690 DOI: 10.1113/jp275175] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [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] [Received: 09/01/2017] [Accepted: 11/08/2017] [Indexed: 12/12/2022] Open
Abstract
KEY POINTS TMEM16 proteins can operate as Ca2+ -activated Cl- channels or scramble membrane phospholipids, which are both highly relevant mechanisms during disease. Overexpression of TMEM16A and TMEM16F were found to be partially active at 37°C and at resting intracellular Ca2+ concentrations. We show that TMEM16 Cl- currents and phospholipid scrambling can be activated by modification of plasma membrane phospholipids, through reactive oxygen species and phospholipase A2. While phospholipids and Cl- ions are likely to use the same pore within TMEM16F, TMEM16A only conducts Cl- ions. Lipid regulation of TMEM16 proteins is highly relevant during inflammation and regulated cell death such as apoptosis and ferroptosis. ABSTRACT TMEM16/anoctamin (ANO) proteins form Ca2+ -activated ion channels or phospholipid scramblases. We found that both TMEM16A/ANO1 and TMEM16F/ANO6 produced Cl- currents when activated by intracellular Ca2+ , but only TMEM16F was able to expose phosphatidylserine to the outer leaflet of the plasma membrane. Mutations within TMEM16F or TMEM16A/F chimeras similarly changed Cl- currents and phospholipid scrambling, suggesting the same intramolecular pathway for Cl- and phospholipids. When overexpressed, TMEM16A and TMEM16F produced spontaneous Cl- currents at 37°C even at resting intracellular Ca2+ levels, which was abolished by inhibition of phospholipase A2 (PLA2 ). Connversely, activation of PLA2 or application of active PLA2 , as well as lipid peroxidation induced by reactive oxygen species (ROS) using staurosporine or tert-butyl hydroperoxide, enhanced ion currents by TMEM16A/F and in addition activated phospholipid scrambling by TMEM16F. Thus, TMEM16 proteins are activated by an increase in intracellular Ca2+ , or independent of intracellular Ca2+ , by modifications occurring in plasma and intracellular membrane phospholipids. These results may help to explain why regions distant to the TMEM16 pore and the Ca2+ binding sites control Cl- currents and phospholipid scrambling. Regulation of TMEM16 proteins through modification of membrane phospholipids occurs during regulated cell death such as apoptosis and ferroptosis. It contributes to inflammatory and nerve injury-induced hypersensitivity and generation of pain and therefore provides a regulatory mechanism that is particularly relevant during disease.
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Affiliation(s)
- Rainer Schreiber
- Institut für PhysiologieUniversität RegensburgUniversitätsstraße 31D‐93053RegensburgGermany
| | - Jiraporn Ousingsawat
- Institut für PhysiologieUniversität RegensburgUniversitätsstraße 31D‐93053RegensburgGermany
| | | | - Lalida Sirianant
- Institut für PhysiologieUniversität RegensburgUniversitätsstraße 31D‐93053RegensburgGermany
| | - Roberta Benedetto
- Institut für PhysiologieUniversität RegensburgUniversitätsstraße 31D‐93053RegensburgGermany
| | - Karina Reiss
- Department of DermatologyUniversity of KielSchittenhelmstrasse 7Kiel24105Germany
| | - Karl Kunzelmann
- Institut für PhysiologieUniversität RegensburgUniversitätsstraße 31D‐93053RegensburgGermany
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Benedetto R, Ousingsawat J, Wanitchakool P, Zhang Y, Holtzman MJ, Amaral M, Rock JR, Schreiber R, Kunzelmann K. Epithelial Chloride Transport by CFTR Requires TMEM16A. Sci Rep 2017; 7:12397. [PMID: 28963502 PMCID: PMC5622110 DOI: 10.1038/s41598-017-10910-0] [Citation(s) in RCA: 88] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 08/16/2017] [Indexed: 12/15/2022] Open
Abstract
Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) is the secretory chloride/bicarbonate channel in airways and intestine that is activated through ATP binding and phosphorylation by protein kinase A, but fails to operate in cystic fibrosis (CF). TMEM16A (also known as anoctamin 1, ANO1) is thought to function as the Ca2+ activated secretory chloride channel independent of CFTR. Here we report that tissue specific knockout of the TMEM16A gene in mouse intestine and airways not only eliminates Ca2+-activated Cl− currents, but unexpectedly also abrogates CFTR-mediated Cl− secretion and completely abolishes cAMP-activated whole cell currents. The data demonstrate fundamentally new roles of TMEM16A in differentiated epithelial cells: TMEM16A provides a mechanism for enhanced ER Ca2+ store release, possibly engaging Store Operated cAMP Signaling (SOcAMPS) and activating Ca2+ regulated adenylyl cyclases. TMEM16A is shown to be essential for proper activation and membrane expression of CFTR. This intimate regulatory relationship is the cause for the functional overlap of CFTR and Ca2+-dependent chloride transport.
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Affiliation(s)
- Roberta Benedetto
- 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
| | - Podchanart Wanitchakool
- Physiological institute, University of Regensburg, University street 31, D-93053, Regensburg, Germany
| | - Yong Zhang
- Department of Medicine and Department of Cell Biology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Michael J Holtzman
- Department of Medicine and Department of Cell Biology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Margarida Amaral
- University of Lisboa, Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, C8, 1749-016, Lisboa, Portugal
| | - Jason R Rock
- Department of Anatomy, University of California, San Francisco, USA
| | - 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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Simões F, Ousingsawat J, Wanitchakool P, Fonseca A, Cabrita I, Benedetto R, Schreiber R, Kunzelmann K. CFTR supports cell death through ROS-dependent activation of TMEM16F (anoctamin 6). Pflugers Arch 2017; 470:305-314. [DOI: 10.1007/s00424-017-2065-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Revised: 07/25/2017] [Accepted: 08/28/2017] [Indexed: 12/11/2022]
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Wanitchakool P, Ousingsawat J, Sirianant L, Cabrita I, Faria D, Schreiber R, Kunzelmann K. Cellular defects by deletion of ANO10 are due to deregulated local calcium signaling. Cell Signal 2016; 30:41-49. [PMID: 27838374 DOI: 10.1016/j.cellsig.2016.11.006] [Citation(s) in RCA: 36] [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: 09/27/2016] [Accepted: 11/07/2016] [Indexed: 12/20/2022]
Abstract
TMEM16K (ANO10) belongs to a family of ion channels and phospholipid scramblases. Mutations in ANO10 cause neurological and immunological defects, and abrogated ion transport. Here we show that Ano10 knockout in epithelial cells leads to defective ion transport, attenuated volume regulation and deranged Ca2+ signaling. Intestinal epithelial cells from Ano10 null mice are reduced in size and demonstrate an almost abolished spontaneous and TNFα-induced apoptosis. Similar defects were found in mouse peritoneal Ano10 null macrophages and in human THP1 macrophages with reduced ANO10 expression. A cell cycle dependent colocalization of Ano10 with acetylated tubulin, centrioles, and a submembranous tubulin containing compartment was observed in Fisher rat thyroid cells. Axs, the Drosophila ortholog of ANO10 is known for its role in mitotic spindle formation and association with the endoplasmic reticulum and Ca2+ signaling. We therefore propose that mutations in ANO10 cause cellular defects and genetic disorders through deranged local Ca2+ signaling.
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Affiliation(s)
- Podchanart Wanitchakool
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
| | - Jiraporn Ousingsawat
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
| | - Lalida Sirianant
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
| | - Inês Cabrita
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
| | - Diana Faria
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
| | - Rainer Schreiber
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
| | - Karl Kunzelmann
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany.
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Wanitchakool P, Ousingsawat J, Sirianant L, MacAulay N, Schreiber R, Kunzelmann K. Cl - channels in apoptosis. Eur Biophys J 2016; 45:599-610. [PMID: 27270446 DOI: 10.1007/s00249-016-1140-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 05/06/2016] [Accepted: 05/14/2016] [Indexed: 12/28/2022]
Abstract
A remarkable feature of apoptosis is the initial massive cell shrinkage, which requires opening of ion channels to allow release of K+, Cl-, and organic osmolytes to drive osmotic water movement and cell shrinkage. This article focuses on the role of the Cl- channels LRRC8, TMEM16/anoctamin, and cystic fibrosis transmembrane conductance regulator (CFTR) in cellular apoptosis. LRRC8A-E has been identified as a volume-regulated anion channel expressed in many cell types. It was shown to be required for regulatory and apoptotic volume decrease (RVD, AVD) in cultured cell lines. Its presence also determines sensitivity towards cytostatic drugs such as cisplatin. Recent data point to a molecular and functional relationship of LRRC8A and anoctamins (ANOs). ANO6, 9, and 10 (TMEM16F, J, and K) augment apoptotic Cl- currents and AVD, but it remains unclear whether these anoctamins operate as Cl- channels or as regulators of other apoptotic Cl- channels, such as LRRC8. CFTR has been known for its proapoptotic effects for some time, and this effect may be based on glutathione release from the cell and increase in cytosolic reactive oxygen species (ROS). Although we find that CFTR is activated by cell swelling, it is possible that CFTR serves RVD/AVD through accumulation of ROS and activation of independent membrane channels such as ANO6. Thus activation of ANO6 will support cell shrinkage and induce additional apoptotic events, such as membrane phospholipid scrambling.
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Affiliation(s)
- Podchanart Wanitchakool
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany
| | - Jiraporn Ousingsawat
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany
| | - Lalida Sirianant
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany
| | - Nanna MacAulay
- Department of Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Rainer Schreiber
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany
| | - Karl Kunzelmann
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany.
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Ousingsawat J, Cabrita I, Wanitchakool P, Sirianant L, Krautwald S, Linkermann A, Schreiber R, Kunzelmann K. Ca 2+ signals, cell membrane disintegration, and activation of TMEM16F during necroptosis. Cell Mol Life Sci 2016; 74:173-181. [PMID: 27535660 DOI: 10.1007/s00018-016-2338-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [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: 02/17/2016] [Revised: 08/08/2016] [Accepted: 08/09/2016] [Indexed: 11/29/2022]
Abstract
Activated receptor-interacting protein kinase 3 (RIPK3) and mixed lineage kinase domain like (MLKL) are essential components of the necroptotic pathway. Phosphorylated MLKL (pMLKL) is thought to induce membrane leakage, leading to cell swelling and disintegration of the cell membrane. However, the molecular identity of the necroptotic membrane pore remains unclear, and the role of pMLKL for membrane permeabilization is currently disputed. We observed earlier that the phospholipid scramblase and ion channel TMEM16F/anoctamin 6 cause large membrane currents, cell swelling, and cell death when activated by a strong increase in intracellular Ca2+. We, therefore, asked whether TMEM16F is also central to necroptotic cell death and other cellular events during necroptosis. Necroptosis was induced by TNFα, smac mimetic, and Z-VAD (TSZ) in NIH3T3 fibroblasts and the four additional cell lines HT29, 16HBE, H441, and L929. Time-dependent changes in intracellular Ca2+, cell morphology, and membrane currents were recorded. TSZ induced a small and only transient oscillatory rise in intracellular Ca2+, which was paralleled by the activation of outwardly rectifying Cl- currents, which were typical for TMEM16F/ANO6. Ca2+ oscillations were due to Ca2+ release from endoplasmic reticulum, and were independent of extracellular Ca2+. The initial TSZ-induced cell swelling was followed by cell shrinkage. Using typical channel blockers and siRNA-knockdown, the Cl- currents were shown to be due to the activation of ANO6. However, the knockdown of ANO6 or inhibitors of ANO6 did not inhibit necroptotic cell death. The present data demonstrate the activation of ANO6 during necroptosis, which, however, is not essential for cell death.
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Affiliation(s)
- Jiraporn Ousingsawat
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany
| | - Inês Cabrita
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany
| | - Podchanart Wanitchakool
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany
| | - Lalida Sirianant
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany
| | - Stefan Krautwald
- Division of Nephrology and Hypertension, Christian-Albrechts-University, Kiel, Germany
| | - Andreas Linkermann
- Division of Nephrology and Hypertension, Christian-Albrechts-University, Kiel, Germany
| | - Rainer Schreiber
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany
| | - Karl Kunzelmann
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany.
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Benedetto R, Sirianant L, Pankonien I, Wanitchakool P, Ousingsawat J, Cabrita I, Schreiber R, Amaral M, Kunzelmann K. Relationship between TMEM16A/anoctamin 1 and LRRC8A. Pflugers Arch 2016; 468:1751-63. [PMID: 27514381 DOI: 10.1007/s00424-016-1862-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [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: 04/22/2016] [Revised: 07/23/2016] [Accepted: 07/26/2016] [Indexed: 10/21/2022]
Abstract
TMEM16A/anoctamin 1/ANO1 and VRAC/LRRC8 are independent chloride channels activated either by increase in intracellular Ca(2+) or cell swelling, respectively. In previous studies, we observed overlapping properties for both types of channels. (i) TMEM16A/ANO1 and LRRC8 are inhibited by identical compounds, (ii) the volume-regulated anion channel VRAC requires compartmentalized Ca(2+) increase to be fully activated, (iii) anoctamins are activated by cell swelling, (iv) both channels have a role for apoptotic cell death, (v) both channels are possibly located in lipid rafts/caveolae like structures, and (vi) VRAC and anoctamin 1 currents are not additive when each are fully activated. In the present study, we demonstrate in different cell types that loss of LRRC8A expression not only inhibited VRAC, but also attenuated Ca(2+) activated Cl(-) currents. Moreover, expression of LRRC8A enhanced Ca(2+) activated Cl(-) currents, and both LRRC8A and ANO1 could be coimmunoprecipitated. We found that LRRC8A becomes accessible to biotinylation upon exposure to hypotonic bath solution, while membrane capacitance was not enhanced. When intracellular Ca(2+) was increased in ANO1-expressing cells, the membrane capacitance was enhanced and increased binding of FM4-64 to the membrane was observed. As this was not seen in cells lacking ANO1 expression, a role of ANO1 for exocytosis was suggested. We propose that ANO1 and LRRC8A are activated in parallel. Thus, ionomycin or purinergic stimulation will not only activate ANO1 but also LRRC8 currents. Cell swelling will not only activate LRRC8/VRAC, but also stimulate ANO1 currents by enhancing compartmentalized Ca(2+) increase and/or through swelling induced autocrine release of ATP.
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Affiliation(s)
- Roberta Benedetto
- Physiological Institute, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany
| | - Lalida Sirianant
- Physiological Institute, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany
| | - Ines Pankonien
- Faculty of Sciences, Biosystems & Integrative Sciences Institute, University of Lisboa, Lisbon, Portugal
| | - Podchanart Wanitchakool
- Physiological Institute, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany
| | - Jiraporn Ousingsawat
- Physiological Institute, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany
| | - Ines Cabrita
- Physiological Institute, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany
| | - Rainer Schreiber
- Physiological Institute, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany
| | - Margarida Amaral
- Faculty of Sciences, Biosystems & Integrative Sciences Institute, University of Lisboa, Lisbon, Portugal
| | - Karl Kunzelmann
- Physiological Institute, University of Regensburg, Universitätsstraße 31, D-93053, Regensburg, Germany.
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Sirianant L, Wanitchakool P, Ousingsawat J, Benedetto R, Zormpa A, Cabrita I, Schreiber R, Kunzelmann K. Non-essential contribution of LRRC8A to volume regulation. Pflugers Arch 2016; 468:805-16. [DOI: 10.1007/s00424-016-1789-6] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2016] [Accepted: 01/06/2016] [Indexed: 10/22/2022]
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Hammer C, Wanitchakool P, Sirianant L, Papiol S, Monnheimer M, Faria D, Ousingsawat J, Schramek N, Schmitt C, Margos G, Michel A, Kraiczy P, Pawlita M, Schreiber R, Schulz TF, Fingerle V, Tumani H, Ehrenreich H, Kunzelmann K. A Coding Variant of ANO10, Affecting Volume Regulation of Macrophages, Is Associated with Borrelia Seropositivity. Mol Med 2015; 21:26-37. [PMID: 25730773 DOI: 10.2119/molmed.2014.00219] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Accepted: 02/23/2015] [Indexed: 01/12/2023] Open
Abstract
In a first genome-wide association study (GWAS) approach to anti-Borrelia seropositivity, we identified two significant single nucleotide polymorphisms (SNPs) (rs17850869, P = 4.17E-09; rs41289586, P = 7.18E-08). Both markers, located on chromosomes 16 and 3, respectively, are within or close to genes previously connected to spinocerebellar ataxia. The risk SNP rs41289586 represents a missense variant (R263H) of anoctamin 10 (ANO10), a member of a protein family encoding Cl(-) channels and phospholipid scramblases. ANO10 augments volume-regulated Cl(-) currents (IHypo) in Xenopus oocytes, HEK293 cells, lymphocytes and macrophages and controls volume regulation by enhancing regulatory volume decrease (RVD). ANO10 supports migration of macrophages and phagocytosis of spirochetes. The R263H variant is inhibitory on IHypo, RVD and intracellular Ca(2+) signals, which may delay spirochete clearance, thereby sensitizing adaptive immunity. Our data demonstrate for the first time that ANO10 has a central role in innate immune defense against Borrelia infection.
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Affiliation(s)
- Christian Hammer
- Clinical Neuroscience, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | | | - Lalida Sirianant
- Institut für Physiologie, Universität Regensburg, Regensburg, Germany
| | - Sergi Papiol
- Clinical Neuroscience, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Mathieu Monnheimer
- Clinical Neuroscience, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Diana Faria
- Institut für Physiologie, Universität Regensburg, Regensburg, Germany
| | | | | | - Corinna Schmitt
- Institute of Virology, Hannover Medical School, Hannover, Germany
| | - Gabriele Margos
- National Reference Center for Borrelia, Bavarian Health and Food Safety Authority, Oberschleissheim, Germany
| | - Angelika Michel
- Division of Genome Modifications and Carcinogenesis, Infections and Cancer Program, German Cancer Research Center, Heidelberg, Germany
| | - Peter Kraiczy
- Institute of Medical Microbiology and Infection Control, University Hospital of Frankfurt am Main, Frankfurt/Main, Germany
| | - Michael Pawlita
- Division of Genome Modifications and Carcinogenesis, Infections and Cancer Program, German Cancer Research Center, Heidelberg, Germany
| | - Rainer Schreiber
- Institut für Physiologie, Universität Regensburg, Regensburg, Germany
| | - Thomas F Schulz
- Institute of Virology, Hannover Medical School, Hannover, Germany
| | - Volker Fingerle
- National Reference Center for Borrelia, Bavarian Health and Food Safety Authority, Oberschleissheim, Germany
| | | | - Hannelore Ehrenreich
- Clinical Neuroscience, Max Planck Institute of Experimental Medicine, Göttingen, Germany.,DFG Research Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany
| | - Karl Kunzelmann
- Institut für Physiologie, Universität Regensburg, Regensburg, Germany
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Ousingsawat J, Wanitchakool P, Kmit A, Romao AM, Jantarajit W, Schreiber R, Kunzelmann K. Anoctamin 6 mediates effects essential for innate immunity downstream of P2X7 receptors in macrophages. Nat Commun 2015; 6:6245. [PMID: 25651887 DOI: 10.1038/ncomms7245] [Citation(s) in RCA: 114] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2014] [Accepted: 01/08/2015] [Indexed: 12/18/2022] Open
Abstract
Purinergic P2X7 receptors (P2X7R) are fundamental to innate immune response. In macrophages, transient stimulation of P2X7R activates several transport mechanisms and induces the scrambling of phospholipids with subsequent membrane blebbing and apoptosis. These processes support phagocytosis and subsequent killing of phagocytosed bacteria. Here we demonstrate that the stimulation of P2X7 receptors activates anoctamin 6 (ANO6, TMEM16F), a protein that functions as Ca(2+) dependent phospholipid scramblase and Ca(2+)-activated Cl(-) channel. Inhibition or knockdown of ANO6 attenuates ATP-induced cell shrinkage, cell migration and phospholipid scrambling. In mouse macrophages, Ano6 produces large ion currents by stimulation of P2X7 receptors and contributes to ATP-induced membrane blebbing and apoptosis, which is largely reduced in macrophages from Ano6-/- mice. ANO6 supports bacterial phagocytosis and killing by mouse and human THP-1 macrophages. Our data demonstrate that anoctamin 6 is an essential component of the immune defense by macrophages.
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Affiliation(s)
- Jiraporn Ousingsawat
- Physiological Institute, University of Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
| | - Podchanart Wanitchakool
- Physiological Institute, University of Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
| | - Arthur Kmit
- Physiological Institute, University of Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
| | - Ana M Romao
- Physiological Institute, University of Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
| | - Walailak Jantarajit
- Physiological Institute, University of Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
| | - Rainer Schreiber
- Physiological Institute, University of Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
| | - Karl Kunzelmann
- Physiological Institute, University of Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
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Ousingsawat J, Wanitchakool P, Schreiber R, Wuelling M, Vortkamp A, Kunzelmann K. Anoctamin-6 controls bone mineralization by activating the calcium transporter NCX1. J Biol Chem 2015; 290:6270-80. [PMID: 25589784 DOI: 10.1074/jbc.m114.602979] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Anoctamin-6 (Ano6, TMEM16F) belongs to a family of putative Ca(2+)-activated Cl(-) channels and operates as membrane phospholipid scramblase. Deletion of Ano6 leads to reduced skeleton size, skeletal deformities, and mineralization defects in mice. However, it remains entirely unclear how a lack of Ano6 leads to a delay in bone mineralization by osteoblasts. The Na(+)/Ca(2+) exchanger NCX1 was found to interact with Ano6 in a two-hybrid split-ubiquitin screen. Using human osteoblasts and osteoblasts from Ano6(-/-) and WT mice, we demonstrate that NCX1 requires Ano6 to efficiently translocate Ca(2+) out of osteoblasts into the calcifying bone matrix. Ca(2+)-activated anion currents are missing in primary osteoblasts isolated from Ano6 null mice. Our findings demonstrate the importance of NCX1 for bone mineralization and explain why deletion of an ion channel leads to the observed mineralization defect: Ano6 Cl(-) currents are probably required to operate as a Cl(-) bypass channel, thereby compensating net Na(+) charge movement by NCX1.
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Affiliation(s)
- Jiraporn Ousingsawat
- From the Institut für Physiologie, Universität Regensburg, D-93053 Regensburg and
| | | | - Rainer Schreiber
- From the Institut für Physiologie, Universität Regensburg, D-93053 Regensburg and
| | - Manuela Wuelling
- the Department Entwicklungsbiologie, Fakultät für Biologie, Universität Duisburg-Essen, 45141 Essen, Germany
| | - Andrea Vortkamp
- the Department Entwicklungsbiologie, Fakultät für Biologie, Universität Duisburg-Essen, 45141 Essen, Germany
| | - Karl Kunzelmann
- From the Institut für Physiologie, Universität Regensburg, D-93053 Regensburg and
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Sirianant L, Ousingsawat J, Tian Y, Schreiber R, Kunzelmann K. TMC8 (EVER2) attenuates intracellular signaling by Zn2+ and Ca2+ and suppresses activation of Cl- currents. Cell Signal 2014; 26:2826-33. [PMID: 25220380 DOI: 10.1016/j.cellsig.2014.09.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Revised: 09/01/2014] [Accepted: 09/02/2014] [Indexed: 11/25/2022]
Abstract
Eight paralogue members form the family of transmembrane channel-like (TMC) proteins that share considerable sequence homology to anoctamin 1 (Ano1, TMEM16A). Ano1 is a Ca(2+) activated Cl(-) channel that is related to head and neck cancer, often caused by human papilloma virus (HPV) infection. Mutations in TMC 6 and 8 (EVER1, EVER2) cause epidermodysplasia verruciformis. This rare skin disease is characterized by abnormal susceptibility to HPV infection and cancer. We found that in contrast to Ano1 the common paralogues TMC4-TMC8 did not produce Ca(2+) activated Cl(-) currents when expressed in HEK293 cells. On the contrary, TMC8 was found to be localized in the endoplasmic reticulum (ER), where it inhibited receptor mediated Ca(2+) release, activation of Ano1 and volume regulated LRRC8-related Cl(-) currents. Zn(2+) is co-released from the ER together with Ca(2+) and thereby further augments Ca(2+) store release. Because TMC8 is required to lower cytosolic Zn(2+) concentrations by the Zn(2+) transporter ZnT-1, we hypothesize that HPV infections and cancer caused by mutations in TMC8 are related to upregulated Zn(2+)/Ca(2+) signaling and activation of Ano1.
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Affiliation(s)
- Lalida Sirianant
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
| | - Jiraporn Ousingsawat
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
| | - Yuemin Tian
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
| | - Rainer Schreiber
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
| | - Karl Kunzelmann
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany.
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Kunzelmann K, Nilius B, Owsianik G, Schreiber R, Ousingsawat J, Sirianant L, Wanitchakool P, Bevers EM, Heemskerk JWM. Molecular functions of anoctamin 6 (TMEM16F): a chloride channel, cation channel, or phospholipid scramblase? Pflugers Arch 2014; 466:407-14. [PMID: 23748496 DOI: 10.1007/s00424-013-1305-1] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Revised: 05/27/2013] [Accepted: 05/28/2013] [Indexed: 10/26/2022]
Abstract
Anoctamin 6 (Ano6; TMEM16F gene) is a ubiquitous protein; the expression of which is defective in patients with Scott syndrome, an inherited bleeding disorder based on defective scrambling of plasma membrane phospholipids. For Ano6, quite diverse functions have been described: (1) it can form an outwardly rectifying, Ca(2+)-dependent and a volume-regulated Cl(-) channel; (2) it was claimed to be a Ca(2+)-regulated nonselective cation channel permeable for Ca(2+); (3) it was shown to be essential for Ca(2+)-mediated scrambling of membrane phospholipids; and (4) it can regulate cell blebbing and microparticle shedding. Deficiency of Ano6 in blood cells from Scott patients or Ano6 null mice appears to affect all of these cell responses. Furthermore, Ano6 deficiency in mice impairs the mineralization of osteoblasts, resulting in reduced skeletal development. These diverse results have been obtained under different experimental conditions, which may explain some of the contradictions. This review therefore aims to summarize the currently available information on the diverse roles of Ano6 and tries to clear up some of the existing controversies.
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Affiliation(s)
- Karl Kunzelmann
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany,
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Kmit A, van Kruchten R, Ousingsawat J, Mattheij NJA, Senden-Gijsbers B, Heemskerk JWM, Schreiber R, Bevers EM, Kunzelmann K. Calcium-activated and apoptotic phospholipid scrambling induced by Ano6 can occur independently of Ano6 ion currents. Cell Death Dis 2013; 4:e611. [PMID: 23618909 PMCID: PMC3668637 DOI: 10.1038/cddis.2013.135] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Revised: 02/16/2013] [Accepted: 03/11/2013] [Indexed: 11/17/2022]
Abstract
Immune cells and platelets maintain plasma membrane phospholipid asymmetry. Upon activation, this asymmetry is disrupted by phospholipid scrambling (PS), which is a major step during activation of immune cells, hemostasis and apoptosis. Anoctamin 6 (Ano6; TMEM16F) causes chloride (Cl(-)) and cation currents and is required for Ca(2+)-dependent PS. It is defective in blood cells from patients with Scott syndrome, a rare bleeding disorder. We examined if Cl(-) currents and PS are related, whether both processes are Ca(2+) dependent, and whether Ca(2+)-independent scrambling during intrinsic and extrinsic apoptosis is controlled by Ano6. Ca(2+) increase by ionomycin activated Ano6 Cl(-) currents and PS in normal lymphocytes, but not in B-lymphocytes from two different patients with Scott syndrome. Fas ligand (FasL) did not increase intracellular Ca(2+), but activated Cl(-) currents in normal but not in Scott lymphocytes. Whole-cell currents were inhibited by Cl(-) channel blockers and by siRNA knockdown of Ano6. In contrast, intrinsic mitochondrial apoptosis by ABT-737 did not induce Cl(-) currents in lymphocytes. PS was not inhibited by blockers of Ano6 or removal of Cl(-) ions. Remarkably, Ca(2+)-independent scrambling due to extrinsic (FasL) or intrinsic (ABT-737) apoptosis was unchanged in Scott cells. We conclude that: (i) Ano6 Cl(-) currents are activated by increase in cytosolic Ca(2+), or Ca(2+) independent by stimulation of Fas receptors; (ii) Ca(2+)-dependent PS induced by Ano6 does not require Cl(-) currents; (iii) Ca(2+)-independent PS does not require Ano6; (iv) Ano6 is necessary for Ca(2+)-dependent PS, but not by increasing intracellular Ca(2+).
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Affiliation(s)
- A Kmit
- Institut für Physiologie, Universität Regensburg, Regensburg, Germany
| | - R van Kruchten
- Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, The Netherlands
| | - J Ousingsawat
- Institut für Physiologie, Universität Regensburg, Regensburg, Germany
| | - N J A Mattheij
- Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, The Netherlands
| | - B Senden-Gijsbers
- Department of Internal Medicine, Division of Haematology, Maastricht University Medical Center, Maastricht, The Netherlands
| | - J W M Heemskerk
- Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, The Netherlands
| | - R Schreiber
- Institut für Physiologie, Universität Regensburg, Regensburg, Germany
| | - E M Bevers
- Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, The Netherlands
| | - K Kunzelmann
- Institut für Physiologie, Universität Regensburg, Regensburg, Germany
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Kunzelmann K, Tian Y, Martins JR, Faria D, Kongsuphol P, Ousingsawat J, Wolf L, Schreiber R. Airway epithelial cells--functional links between CFTR and anoctamin dependent Cl- secretion. Int J Biochem Cell Biol 2012; 44:1897-900. [PMID: 22710346 DOI: 10.1016/j.biocel.2012.06.011] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Revised: 06/02/2012] [Accepted: 06/11/2012] [Indexed: 11/29/2022]
Abstract
Airways consist of a heterogeneous population of cells, comprising ciliated cells, Clara cells and goblet cells. Electrolyte secretion by the airways is necessary to produce the airway surface liquid that allows for mucociliary clearance of the lungs. Secretion is driven by opening of Cl(-) selective ion channels in the apical membrane of airway epithelial cells, through either receptor mediated increase in intracellular cAMP or cytosolic Ca(2+). Traditionally cAMP-dependent and Ca(2+)-dependent secretory pathways are regarded as independent. However, this concept has been challenged recently. With identification of the Ca(2+) activated Cl(-) channel TMEM16A (anoctamin 1) and with detailed knowledge of the cAMP-regulated cystic fibrosis transmembrane conductance regulator (CFTR), it has become possible to look more closely into this relationship.
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Affiliation(s)
- Karl Kunzelmann
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany.
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Ousingsawat J, Schreiber R, Kunzelmann K. Differential contribution of SLC26A9 to Cl(-) conductance in polarized and non-polarized epithelial cells. J Cell Physiol 2012; 227:2323-9. [PMID: 21809345 DOI: 10.1002/jcp.22967] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
SLC26 proteins function as anion exchangers and Cl(-) channels. SLC26A9 has been proposed to be a constitutively active and CFTR-regulated anion conductance in human bronchial epithelia. This positive interaction between two Cl(-) channels has been questioned by others and evidence has been provided that CFTR rather inhibits the transport activity of SLC26A9. We therefore examined the functional interaction between CFTR and SLC26A9 in polarized airway epithelial cells and in non-polarized HEK293 cells expressing CFTR and SLC26A9. We found that SLC26A9 provides a constitutively active basal Cl(-) conductance in polarized grown CFTR-expressing CFBE airway epithelial cells, but not in cells expressing F508del-CFTR. In polarized CFTR-expressing cells, SLC26A9 also contributes to both Ca(2+) - and CFTR-activated Cl(-) secretion. In contrast in non-polarized HEK293 cells co-expressing CFTR/SLC26A9, the baseline Cl(-) conductance provided by SLC26A9 was inhibited during activation of CFTR. SLC26A9 and CFTR behave differentially in polarized and non-polarized cells, which may explain earlier conflicting data.
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Affiliation(s)
- Jiraporn Ousingsawat
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, Regensburg, Germany
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Kunzelmann K, Schreiber R, Kmit A, Jantarajit W, Martins JR, Faria D, Kongsuphol P, Ousingsawat J, Tian Y. Expression and function of epithelial anoctamins. Exp Physiol 2011; 97:184-92. [PMID: 21908539 DOI: 10.1113/expphysiol.2011.058206] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Endogenous Ca(2+)-activated Cl(-) currents (CaCCs) are abundant and present in very different cell types. Very good evidence has been provided that endogenous CaCC is produced by anoctamin 1 (Ano1) and Ano2. Insight into the physiological role of anoctamins has been provided for Ano1, Ano2 and Ano6; however, the physiological role of the other seven members of the anoctamin family remains obscure. Anoctamins 1 and 2 may operate as individual Ca(2+)-sensitive channel proteins or may require accessory subunits for complete function. We find that overexpressed Ano1 has properties resembling all those of endogenous CaCCs, although with some noticeable biophysical and regulatory differences when compared with endogenous channels. Apart from Ano1 and Ano2, expression of Ano6 also produces a Cl(-) conductance. Depending on the cellular background, Ano6 currents may have variable properties. Anoctamins 1 and 6 are frequent in epithelial cells, often coexpressed together with Ano8, Ano9 and Ano10. Most available data on anoctamins were obtained from mouse tissues and from cultured cells, which may not be representative of native human tissues.
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Affiliation(s)
- Karl Kunzelmann
- Universität Regensburg, Institut für Physiologie, Universitätsstraße 31, Regensburg, Germany.
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Ousingsawat J, Mirza M, Tian Y, Roussa E, Schreiber R, Cook DI, Kunzelmann K. Rotavirus toxin NSP4 induces diarrhea by activation of TMEM16A and inhibition of Na+ absorption. Pflugers Arch 2011; 461:579-89. [PMID: 21399895 DOI: 10.1007/s00424-011-0947-0] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Revised: 02/18/2011] [Accepted: 02/21/2011] [Indexed: 01/05/2023]
Abstract
Rotavirus infection is the most frequent cause for severe diarrhea in infants, killing more than 600,000 every year. The nonstructural protein NSP4 acts as a rotavirus enterotoxin, inducing secretory diarrhea without any structural organ damage. Electrolyte transport was assessed in the colonic epithelium from pups and adult mice using Ussing chamber recordings. Western blots and immunocytochemistry was performed in intestinal tissues from wild-type and TMEM16A knockout mice. Ion channel currents were recorded using patch clamp techniques. We show that the synthetic NSP4(114-135) peptide uses multiple pro-secretory pathways to induce diarrhea, by activating the recently identified Ca2+ -activated Cl- channel TMEM16A, and by inhibiting Na+ absorption by the epithelial Na+ channel ENaC and the Na+ /glucose cotransporter SGLT1. Activation of secretion and inhibition of Na+ absorption by NSP4(114-135), respectively, could be potently suppressed by wheat germ agglutinin which probably competes with NSP4(114-135) for binding to an unknown glycolipid receptor. The present paper gives a clue as to mechanisms of rotavirus-induced diarrhea and suggests wheat germ agglutinin as a simple and effective therapy.
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Affiliation(s)
- Jiraporn Ousingsawat
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany
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Kunzelmann K, Kongsuphol P, Chootip K, Toledo C, Martins JR, Almaca J, Tian Y, Witzgall R, Ousingsawat J, Schreiber R. Role of the Ca2+-activated Cl- channels bestrophin and anoctamin in epithelial cells. Biol Chem 2011; 392:125-34. [DOI: 10.1515/bc.2011.010] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
Two families of proteins, the bestrophins (Best) and the recently cloned TMEM16 proteins (anoctamin, Ano), recapitulate properties of Ca2+-activated Cl- currents. Best1 is strongly expressed in the retinal pigment epithelium and could have a function as a Ca2+-activated Cl- channel as well as a regulator of Ca2+ signaling. It is also present at much lower levels in other cell types including epithelial cells, where it regulates plasma membrane localized Cl- channels by controlling intracellular Ca2+ levels. Best1 interacts with important Ca2+-signaling proteins such as STIM1 and can interact directly with other Ca2+-activated Cl- channels such as TMEM16A. Best1 is detected in the endoplasmic reticulum (ER) where it shapes the dynamic ER structure and regulates cell proliferation, which could be important for renal cystogenesis. Ca2+-activated Cl- channels of the anoctamin family (TMEM16A) show biophysical and pharmacological properties that are typical for endogenous Ca2+-dependent Cl- channels. TMEM16 proteins are abundantly expressed and many reports demonstrate their physiological importance in epithelial as well as non-epithelial cells. These channels are also activated by cell swelling and can therefore control cell volume, proliferation and apoptosis. To fully understand the function and regulation of Ca2+-activated Cl- currents, it is necessary to appreciate that Best1 and TMEM16A are embedded in a protein network and that they probably operate in functional microdomains.
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Ousingsawat J, Kongsuphol P, Schreiber R, Kunzelmann K. CFTR and TMEM16A are Separate but Functionally Related Cl - Channels. Cell Physiol Biochem 2011; 28:715-24. [DOI: 10.1159/000335765] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/19/2011] [Indexed: 11/19/2022] Open
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Tian Y, Kongsuphol P, Hug M, Ousingsawat J, Witzgall R, Schreiber R, Kunzelmann K. Calmodulin-dependent activation of the epithelial calcium-dependent chloride channel TMEM16A. FASEB J 2010; 25:1058-68. [PMID: 21115851 DOI: 10.1096/fj.10-166884] [Citation(s) in RCA: 119] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
TMEM16A (anoctamin 1, Ano1), a member of a family of 10 homologous proteins, has been shown to form an essential component of Ca(2+)-activated Cl(-) channels. TMEM16A-null mice exhibit severe defects in epithelial transport along with tracheomalacia and death within 1 mo after birth. Despite its outstanding physiological significance, the mechanisms for activation of TMEM16A remain obscure. TMEM16A is activated on increase in intracellular Ca(2+), but it is unclear whether Ca(2+) binds directly to the channel or whether additional components are required. We demonstrate that TMEM16A is strictly membrane localized and requires cytoskeletal interactions to be fully activated. Despite the need for cytosolic ATP for full activation, phosphorylation by protein kinases is not required. In contrast, the Ca(2+) binding protein calmodulin appears indispensable and interacts physically with TMEM16A. Openers of small- and intermediate-conductance Ca(2+)-activated potassium channels known to interact with calmodulin, such as 1-EBIO, DCEBIO, or riluzole, also activated TMEM16A. These results reinforce the use of these compounds for activation of electrolyte secretion in diseases such as cystic fibrosis.
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Affiliation(s)
- Yuemin Tian
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
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Skals M, Jensen UB, Ousingsawat J, Kunzelmann K, Leipziger J, Praetorius HA. Escherichia coli alpha-hemolysin triggers shrinkage of erythrocytes via K(Ca)3.1 and TMEM16A channels with subsequent phosphatidylserine exposure. J Biol Chem 2010; 285:15557-15565. [PMID: 20231275 DOI: 10.1074/jbc.m109.082578] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
alpha-Hemolysin from Escherichia coli (HlyA) readily lyse erythrocytes from various species. We have recently demonstrated that this pore-forming toxin provokes distinct shrinkage and crenation before it finally leads to swelling and lysis of erythrocytes. The present study documents the underlying mechanism for this severe volume reduction. We show that HlyA-induced shrinkage and crenation of human erythrocytes occur subsequent to a significant rise in [Ca(2+)](i). The Ca(2+)-activated K(+) channel K(Ca)3.1 (or Gardos channel) is essential for the initial shrinkage, because both clotrimazole and TRAM-34 prevent the shrinkage and potentiate hemolysis produced by HlyA. Notably, the recently described Ca(2+)-activated Cl(-) channel TMEM16A contributes substantially to HlyA-induced cell volume reduction. Erythrocytes isolated from TMEM16A(-/-) mice showed significantly attenuated crenation and increased lysis compared with controls. Additionally, we found that HlyA leads to acute exposure of phosphatidylserine in the outer leaflet of the plasma membrane. This exposure was considerably reduced by K(Ca)3.1 antagonists. In conclusion, this study shows that HlyA triggers acute erythrocyte shrinkage, which depends on Ca(2+)-activated efflux of K(+) via K(Ca)3.1 and Cl(-) via TMEM16A, with subsequent phosphatidylserine exposure. This mechanism might potentially allow HlyA-damaged erythrocytes to be removed from the bloodstream by macrophages and thereby reduce the risk of intravascular hemolysis.
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Affiliation(s)
- Marianne Skals
- Department of Physiology and Biophysics, Aarhus University, 8000 Aarhus, Denmark
| | - Uffe B Jensen
- Institute of Human Genetics, Aarhus University, and Department of Clinical Genetics, Aarhus University Hospital, 8000 Aarhus, Denmark
| | | | - Karl Kunzelmann
- Department of Physiology, University of Regensburg, 93053 Regensburg, Germany
| | - Jens Leipziger
- Department of Physiology and Biophysics, Aarhus University, 8000 Aarhus, Denmark
| | - Helle A Praetorius
- Department of Physiology and Biophysics, Aarhus University, 8000 Aarhus, Denmark.
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Preston P, Wartosch L, Günzel D, Fromm M, Kongsuphol P, Ousingsawat J, Kunzelmann K, Barhanin J, Warth R, Jentsch TJ. Disruption of the K+ channel beta-subunit KCNE3 reveals an important role in intestinal and tracheal Cl- transport. J Biol Chem 2010; 285:7165-75. [PMID: 20051516 DOI: 10.1074/jbc.m109.047829] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The KCNE3 beta-subunit constitutively opens outwardly rectifying KCNQ1 (Kv7.1) K(+) channels by abolishing their voltage-dependent gating. The resulting KCNQ1/KCNE3 heteromers display enhanced sensitivity to K(+) channel inhibitors like chromanol 293B. KCNE3 was also suggested to modify biophysical properties of several other K(+) channels, and a mutation in KCNE3 was proposed to underlie forms of human periodic paralysis. To investigate physiological roles of KCNE3, we now disrupted its gene in mice. kcne3(-/-) mice were viable and fertile and displayed neither periodic paralysis nor other obvious skeletal muscle abnormalities. KCNQ1/KCNE3 heteromers are present in basolateral membranes of intestinal and tracheal epithelial cells where they might facilitate transepithelial Cl(-) secretion through basolateral recycling of K(+) ions and by increasing the electrochemical driving force for apical Cl(-) exit. Indeed, cAMP-stimulated electrogenic Cl(-) secretion across tracheal and intestinal epithelia was drastically reduced in kcne3(-/-) mice. Because the abundance and subcellular localization of KCNQ1 was unchanged in kcne3(-/-) mice, the modification of biophysical properties of KCNQ1 by KCNE3 is essential for its role in intestinal and tracheal transport. Further, these results suggest KCNE3 as a potential modifier gene in cystic fibrosis.
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Affiliation(s)
- Patricia Preston
- Leibniz-Institut für Molekulare Pharmakologie and Max-Delbrück-Centrum für Molekulare Medizin, 13125 Berlin, Germany
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Ousingsawat J, Martins JR, Schreiber R, Rock JR, Harfe BD, Kunzelmann K. Loss of TMEM16A causes a defect in epithelial Ca2+-dependent chloride transport. J Biol Chem 2009; 284:28698-703. [PMID: 19679661 DOI: 10.1074/jbc.m109.012120] [Citation(s) in RCA: 190] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Molecular identification of the Ca(2+)-dependent chloride channel TMEM16A (ANO1) provided a fundamental step in understanding Ca(2+)-dependent Cl(-) secretion in epithelia. TMEM16A is an intrinsic constituent of Ca(2+)-dependent Cl(-) channels in cultured epithelia and may control salivary output, but its physiological role in native epithelial tissues remains largely obscure. Here, we demonstrate that Cl(-) secretion in native epithelia activated by Ca(2+)-dependent agonists is missing in mice lacking expression of TMEM16A. Ca(2+)-dependent Cl(-) transport was missing or largely reduced in isolated tracheal and colonic epithelia, as well as hepatocytes and acinar cells from pancreatic and submandibular glands of TMEM16A(-/-) animals. Measurement of particle transport on the surface of tracheas ex vivo indicated largely reduced mucociliary clearance in TMEM16A(-/-) mice. These results clearly demonstrate the broad physiological role of TMEM16A(-/-) for Ca(2+)-dependent Cl(-) secretion and provide the basis for novel treatments in cystic fibrosis, infectious diarrhea, and Sjöegren syndrome.
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Affiliation(s)
- Jiraporn Ousingsawat
- Institut für Physiologie, Universität Regensburg, Universitätsstrasse 31, D-93053 Regensburg, Germany
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Almaça J, Tian Y, Aldehni F, Ousingsawat J, Kongsuphol P, Rock JR, Harfe BD, Schreiber R, Kunzelmann K. TMEM16 proteins produce volume-regulated chloride currents that are reduced in mice lacking TMEM16A. J Biol Chem 2009; 284:28571-8. [PMID: 19654323 DOI: 10.1074/jbc.m109.010074] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
All vertebrate cells regulate their cell volume by activating chloride channels of unknown molecular identity, thereby activating regulatory volume decrease. We show that the Ca(2+)-activated Cl(-) channel TMEM16A together with other TMEM16 proteins are activated by cell swelling through an autocrine mechanism that involves ATP release and binding to purinergic P2Y(2) receptors. TMEM16A channels are activated by ATP through an increase in intracellular Ca(2+) and a Ca(2+)-independent mechanism engaging extracellular-regulated protein kinases (ERK1/2). The ability of epithelial cells to activate a Cl(-) conductance upon cell swelling, and to decrease their cell volume (regulatory volume decrease) was dependent on TMEM16 proteins. Activation of I(Cl,swell) was reduced in the colonic epithelium and in salivary acinar cells from mice lacking expression of TMEM16A. Thus TMEM16 proteins appear to be a crucial component of epithelial volume-regulated Cl(-) channels and may also have a function during proliferation and apoptotic cell death.
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Affiliation(s)
- Joana Almaça
- Institut für Physiologie, Universität Regensburg, Universitätsstrasse 31, D-93053 Regensburg, Germany
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Almaça J, Kongsuphol P, Hieke B, Ousingsawat J, Viollet B, Schreiber R, Amaral MD, Kunzelmann K. AMPK controls epithelial Na+ channels through Nedd4-2 and causes an epithelial phenotype when mutated. Pflugers Arch 2009; 458:713-21. [DOI: 10.1007/s00424-009-0660-4] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2008] [Accepted: 02/27/2009] [Indexed: 11/30/2022]
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Spitzner M, Martins JR, Soria RB, Ousingsawat J, Scheidt K, Schreiber R, Kunzelmann K. Eag1 and Bestrophin 1 Are Up-regulated in Fast-growing Colonic Cancer Cells. J Biol Chem 2008; 283:7421-8. [DOI: 10.1074/jbc.m703758200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
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Ousingsawat J, Spitzner M, Schreiber R, Kunzelmann K. Upregulation of colonic ion channels in APC ( Min/+ ) mice. Pflugers Arch 2008; 456:847-55. [PMID: 18247045 DOI: 10.1007/s00424-008-0451-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2007] [Revised: 11/21/2007] [Accepted: 01/09/2008] [Indexed: 12/16/2022]
Abstract
The adenomatous polyposis coli (APC) tumor suppressor gene is mutated in almost all human colonic cancers. Disturbances in Na(+) absorption have been observed in colonic cancer, and ion channels such as ether a go-go (Eag) or Ca(2+)-sensitive BK channels have been recognized for their oncogenic potential. APC ( Min/+ ) mice have reduced APC expression and develop multiple intestinal neoplasias (Min). Ion channels in the colonic epithelium were examined using electrophysiology and molecular techniques. APC ( Min/+ ) mice developed intestinal neoplasia and experienced a significant weight loss. Due to intestinal bleedings, the hematocrit was largely reduced and plasma aldosterone levels were enhanced. Rectal potential measurements in vivo indicated an increase in amiloride-sensitive Na(+) absorption in APC ( Min/+ ) mice. Quantitative Ussing chamber studies demonstrated enhanced Na(+) absorption via epithelial Na(+) channels (ENaC) and suggested enhanced activity of oncogenic BK and Eag-1 channels. Patch clamp and fluorescence measurements on isolated crypts suggested enhanced K(+) channel activity in the surface epithelium. ENaC-mRNA and membrane protein expression was enhanced in colonic surface epithelial cells. The data suggest that reduced expression of the APC gene with upregulation of the downstream proteins Akt and mTOR and subsequent hyperaldosteronism is paralleled by upregulation of oncogenic potassium channels and enhanced colonic Na(+) absorption.
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Affiliation(s)
- Jiraporn Ousingsawat
- Institut für Physiologie, Universität Regensburg, Universitätsstrasse 31, 93053, Regensburg, Germany
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