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Zhang M, Gao CX, Wang YP, Ma KT, Li L, Yin JW, Dai ZG, Wang S, Si JQ. The association between the expression of PAR2 and TMEM16A and neuropathic pain. Mol Med Rep 2017; 17:3744-3750. [PMID: 29257338 PMCID: PMC5802179 DOI: 10.3892/mmr.2017.8295] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 12/08/2017] [Indexed: 12/12/2022] Open
Abstract
Chronic constriction injury (CCI) of the sciatic nerve may induce dorsal root ganglion (DRG) neuronal hyperexcitability and behaviorally expressed hyperalgesia. CCI is a model of neuropathic pain. To investigate the association between the expression of protease activated receptor 2 (PAR2), TMEM16A and neuropathic pain, the expression of PAR2 and TMEM16A proteins in the DRG neurons of rats following CCI of the sciatic nerve was investigated. Following the creation of the CCI model, the thermal withdrawal latency (TWL) was examined by a hot plate test. An immunofluorescence assay and western blot assay were performed to determine the expression of PAR2 and TMEM16A proteins in the ipsilateral L4–6 DRG neurons. The concentration of inositol 1,4,5-triphosphate (IP3) in the L4–6 DRG was determined by ELISA. In the CCI-D7 (7 days after CCI) and CCI-D14 (14 days after CCI) treatment groups, the TWL of rats was significantly shorter than that in the sham operated group (P<0.01; n=12). The expression of PAR2 and TMEM16A proteins in the CCI-D7 and CCI-D14 groups were significantly upregulated compared with the sham operated group (P<0.05; n=12). Additionally, it was revealed that PAR2 and TMEM16A were co-expressed in DRG neurons. It was also observed that IP3 significantly increased in the CCI-D7 and CCI-D14 groups compared with the sham operation group (P<0.05; n=6) as PAR2 and TMEM16A also increased. These findings suggest that the upregulation of PAR2 and TMEM16A in DRG neurons, the co-expression of the two proteins and increasing IP3 are critical to the development of neuropathic pain.
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Affiliation(s)
- Meng Zhang
- Department of Anesthesiology, The First Affiliated Hospital of Shihezi University, Shihezi, Xinjiang 832002, P.R. China
| | - Cun-Xiang Gao
- Department of Urology, The First Affiliated Hospital of Shihezi University, Shihezi, Xinjiang 832002, P.R. China
| | - Yan-Ping Wang
- Houbo College, Xinjiang Medical University, Karamay, Xinjiang 834000, P.R. China
| | - Ke-Tao Ma
- Electrophysiological Laboratory, Laboratory of Xinjiang Endemic and Ethnic Diseases, Medical College, Shihezi University, Shihezi, Xinjiang 832002, P.R. China
| | - Li Li
- Electrophysiological Laboratory, Laboratory of Xinjiang Endemic and Ethnic Diseases, Medical College, Shihezi University, Shihezi, Xinjiang 832002, P.R. China
| | - Jiang-Wen Yin
- Department of Anesthesiology, The First Affiliated Hospital of Shihezi University, Shihezi, Xinjiang 832002, P.R. China
| | - Zhi-Gang Dai
- Department of Anesthesiology, The First Affiliated Hospital of Shihezi University, Shihezi, Xinjiang 832002, P.R. China
| | - Sheng Wang
- Department of Anesthesiology, The First Affiliated Hospital of Shihezi University, Shihezi, Xinjiang 832002, P.R. China
| | - Jun-Qiang Si
- Electrophysiological Laboratory, Laboratory of Xinjiang Endemic and Ethnic Diseases, Medical College, Shihezi University, Shihezi, Xinjiang 832002, P.R. China
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Lérias JR, Pinto MC, Botelho HM, Awatade NT, Quaresma MC, Silva IAL, Wanitchakool P, Schreiber R, Pepperkok R, Kunzelmann K, Amaral MD. A novel microscopy-based assay identifies extended synaptotagmin-1 (ESYT1) as a positive regulator of anoctamin 1 traffic. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017; 1865:421-431. [PMID: 29154949 DOI: 10.1016/j.bbamcr.2017.11.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 11/02/2017] [Accepted: 11/14/2017] [Indexed: 01/14/2023]
Abstract
An attractive possibility to treat Cystic Fibrosis (CF), a severe condition caused by dysfunctional CFTR, an epithelial anion channel, is through the activation of alternative (non-CFTR) anion channels. Anoctamin 1 (ANO1) was demonstrated to be a Ca2+-activated chloride channel (CaCC) and thus of high potential to replace CFTR. Despite that ANO1 is expressed in human lung CF tissue, it is present at the cell surface at very low levels. In addition, little is known about regulation of ANO1 traffic, namely which factors promote its plasma membrane (PM) localization. Here, we generated a novel cellular model, expressing an inducible 3HA-ANO1-eGFP construct, and validated its usage as a microscopy tool to monitor for ANO1 traffic. We demonstrate the robustness and specificity of this cell-based assay, by the identification of siRNAs acting both as ANO1 traffic enhancer and inhibitor, targeting respectively COPB1 and ESYT1 (extended synaptotagmin-1), the latter involved in coupling of the endoplasmic reticulum to the PM at specific microdomains. We further show that knockdown of ESYT1 (and family members ESYT2 and ESYT3) significantly decreased ANO1 current density. This ANO1 cell-based assay constitutes an important tool to be further used in high-throughput screens and drug discovery of high relevance for CF and cancer.
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Affiliation(s)
- Joana R Lérias
- University of Lisboa, Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, C8, 1749-016 Lisboa, Portugal; Department of Physiology, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany
| | - Madalena C Pinto
- University of Lisboa, Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, C8, 1749-016 Lisboa, Portugal; Department of Physiology, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany; Cell Biology and Biophysics Unit and Advanced Light Microscopy Facility, European Molecular Biology Laboratory (EMBL), Meyerhofstraße 1, 69117 Heidelberg, Germany
| | - Hugo M Botelho
- University of Lisboa, Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, C8, 1749-016 Lisboa, Portugal
| | - Nikhil T Awatade
- University of Lisboa, Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, C8, 1749-016 Lisboa, Portugal
| | - Margarida C Quaresma
- University of Lisboa, Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, C8, 1749-016 Lisboa, Portugal
| | - Iris A L Silva
- University of Lisboa, Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, C8, 1749-016 Lisboa, Portugal
| | - Podchanart Wanitchakool
- Department of Physiology, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany
| | - Rainer Schreiber
- Department of Physiology, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany
| | - Rainer Pepperkok
- Cell Biology and Biophysics Unit and Advanced Light Microscopy Facility, European Molecular Biology Laboratory (EMBL), Meyerhofstraße 1, 69117 Heidelberg, Germany
| | - Karl Kunzelmann
- Department of Physiology, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany
| | - Margarida D Amaral
- University of Lisboa, Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, C8, 1749-016 Lisboa, Portugal; Cell Biology and Biophysics Unit and Advanced Light Microscopy Facility, European Molecular Biology Laboratory (EMBL), Meyerhofstraße 1, 69117 Heidelberg, Germany.
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53
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Ion channels as targets to treat cystic fibrosis lung disease. J Cyst Fibros 2017; 17:S22-S27. [PMID: 29102290 DOI: 10.1016/j.jcf.2017.10.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 10/09/2017] [Accepted: 10/09/2017] [Indexed: 11/21/2022]
Abstract
Lung health relies on effective mucociliary clearance and innate immune defence mechanisms. In cystic fibrosis (CF), an imbalance in ion transport due to an absence of chloride ion secretion, caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) and a concomitant sodium hyperabsorption, caused by dyregulation of the epithelial sodium channel (ENaC), results in mucus stasis which predisposes the lungs to cycles of chronic infection and inflammation leading to lung function decline. An increased understanding of CFTR structure and function has provided opportunity for the development of a number of novel modulators targeting mutant CFTR however, it is important to also consider other ion channels and transporters present in the airways as putative targets for drug development. In this review, we discuss recent advances in CFTR biology which will contribute to further drug discovery in the field. We also examine developments to inhibit the epithelial sodium channel (ENaC) and potentially activate alternative chloride channels and transporters as a multi-tracked strategy to hydrate CF airways and restore normal mucociliary clearance mechanisms in a manner independent of CFTR mutation.
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ANO9/TMEM16J promotes tumourigenesis via EGFR and is a novel therapeutic target for pancreatic cancer. Br J Cancer 2017; 117:1798-1809. [PMID: 29024940 PMCID: PMC5729472 DOI: 10.1038/bjc.2017.355] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2017] [Revised: 08/30/2017] [Accepted: 09/07/2017] [Indexed: 12/21/2022] Open
Abstract
Background: Anoctamin (ANO)/transmembrane member 16 (TMEM16) proteins mediate diverse physiological and pathophysiological functions including cancer cell proliferation. The present study aimed to identify the role of ANOs in pancreatic cancer. Methods: In an initial screen of ANOs, ANO9/TMEM16J was overexpressed in pancreatic cancer cells, and its role in the pathogenesis of pancreatic cancer was evaluated using an integrated in vitro and in vivo approach. To determine clinical relevance of the experimental findings, the prognostic value of ANO9 was evaluated in patients with pancreatic cancer. Results: The ANO9 mRNA and protein levels were increased in pancreatic cancer-derived cells. Exogenous expression of ANO9 in PANC-1 cells significantly increased cell proliferation in cell cultures and in mice. In contrast, knockdown of ANO9 in AsPC-1, BxPC-3, and Capan-2 cells strongly inhibited cell proliferation. Mechanistic analysis suggested that physical association of ANO9 with epidermal growth factor receptor (EGFR) underlies ANO9-induced cell proliferation. Knockdown of ANO9 augmented the effects of the EGFR inhibitor and the cytotoxic agent on pancreatic cancer cell proliferation. In addition, high ANO9 expression is a poor prognostic factor in patients with pancreatic cancer. Conclusions: The ANO9/TMEM16J appears to be a clinically useful prognostic marker for pancreatic cancer and a potential therapeutic target.
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MicroRNA-9 downregulates the ANO1 chloride channel and contributes to cystic fibrosis lung pathology. Nat Commun 2017; 8:710. [PMID: 28955034 PMCID: PMC5617894 DOI: 10.1038/s41467-017-00813-z] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 07/30/2017] [Indexed: 01/06/2023] Open
Abstract
Cystic fibrosis results from reduced cystic fibrosis transmembrane conductance regulator protein activity leading to defective epithelial ion transport. Ca2+-activated Cl− channels mediate physiological functions independently of cystic fibrosis transmembrane conductance regulator. Anoctamin 1 (ANO1/TMEM16A) was identified as the major Ca2+-activated Cl− channel in airway epithelial cells, and we recently demonstrated that downregulation of the anoctamin 1 channel in cystic fibrosis patients contributes to disease severity via an unknown mechanism. Here we show that microRNA-9 (miR-9) contributes to cystic fibrosis and downregulates anoctamin 1 by directly targeting its 3′UTR. We present a potential therapy based on blockage of miR-9 binding to the 3′UTR by using a microRNA target site blocker to increase anoctamin 1 activity and thus compensate for the cystic fibrosis transmembrane conductance regulator deficiency. The target site blocker is tested in in vitro and in mouse models of cystic fibrosis, and could be considered as an alternative strategy to treat cystic fibrosis. Downregulation of the anoctamin 1 calcium channel in airway epithelial cells contributes to pathology in cystic fibrosis. Here the authors show that microRNA-9 targets anoctamin 1 and that inhibiting this interaction improves mucus dynamics in mouse models.
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56
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Varga G, DenBesten P, Rácz R, Zsembery Á. Importance of bicarbonate transport in pH control during amelogenesis - need for functional studies. Oral Dis 2017; 24:879-890. [PMID: 28834043 DOI: 10.1111/odi.12738] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 08/13/2017] [Indexed: 12/27/2022]
Abstract
Dental enamel, the hardest mammalian tissue, is produced by ameloblasts. Ameloblasts show many similarities to other transporting epithelia although their secretory product, the enamel matrix, is quite different. Ameloblasts direct the formation of hydroxyapatite crystals, which liberate large quantities of protons that then need to be buffered to allow mineralization to proceed. Buffering requires a tight pH regulation and secretion of bicarbonate by ameloblasts. Many investigations have used immunohistochemical and knockout studies to determine the effects of these genes on enamel formation, but up till recently very little functional data were available for mineral ion transport. To address this, we developed a novel 2D in vitro model using HAT-7 ameloblast cells. HAT-7 cells can be polarized and develop functional tight junctions. Furthermore, they are able to accumulate bicarbonate ions from the basolateral to the apical fluid spaces. We propose that in the future, the HAT-7 2D system along with similar cellular models will be useful to functionally model ion transport processes during amelogenesis. Additionally, we also suggest that similar approaches will allow a better understanding of the regulation of the cycling process in maturation-stage ameloblasts, and the pH sensory mechanisms, which are required to develop sound, healthy enamel.
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Affiliation(s)
- G Varga
- Department of Oral Biology, Semmelweis University, Budapest, Hungary
| | - P DenBesten
- Department of Orofacial Sciences, University of California, San Francisco, CA, USA
| | - R Rácz
- Department of Oral Biology, Semmelweis University, Budapest, Hungary
| | - Á Zsembery
- Department of Oral Biology, Semmelweis University, Budapest, Hungary
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Hannigan KI, Griffin CS, Large RJ, Sergeant GP, Hollywood MA, McHale NG, Thornbury KD. The role of Ca 2+-activated Cl - current in tone generation in the rabbit corpus cavernosum. Am J Physiol Cell Physiol 2017; 313:C475-C486. [PMID: 28835432 DOI: 10.1152/ajpcell.00025.2017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 08/03/2017] [Accepted: 08/09/2017] [Indexed: 11/22/2022]
Abstract
Rabbit corpus cavernosum smooth muscle (RCCSM) cells express ion channels that produce Ca2+-activated Cl- (IClCa) current, but low sensitivity to conventional antagonists has made its role in tone generation difficult to evaluate. We have reexamined this question using two new generation IClCa blockers, T16Ainh-A01 and CaCCinh-A01. Isolated RCCSM cells were studied using the perforated patch method. Current-voltage protocols revealed that both L-type Ca2+ current and IClCa T16Ainh-A01 and CaCCinh-A01 (10 μM) reduced IClCa by ~85%, while 30 μM abolished it. L-type Ca2+ current was unaffected by 10 μM CaCCinh-A01 but was reduced by 50% at 30 μM CaCCinh-A01, 46% at 10 μM T16Ainh-A01, and 78% at 30 μM T16Ainh-A01. Both drugs reduced spontaneous isometric tension in RCCSM strips, by 60-70% at 10 μM and >90% at 30 μM. Phenylephrine (PE)-enhanced tension was also reduced (ED50 = 3 μM, CaCCinh-A01; 14 μM, T16Ainh-A01). CaCCinh-A01 at 10 μM had little effect on 60 mM KCl contractures, though they were reduced by 30 μM CaCCinh-A01 and T16Ainh-A01 (10 μM and 30 μM) consistent with their effects on L-type Ca2+ current. Both drugs also reversed the stimulatory effect of PE on intracellular Ca2+ waves, studied with laser scanning confocal microscopy in isolated RCCSM cells. In conclusion, although both drugs were effective blockers of IClCa, the effect of T16Ainh-A01 on L-type Ca2+ current precludes its use for evaluating the role of IClCa in tone generation. However, 10 μM CaCCinh-A01 selectively blocked IClCa versus L-type Ca2+ current and reduced spontaneous and PE-induced tone, suggesting that IClCa is important in maintaining penile detumescence.
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Affiliation(s)
- Karen I Hannigan
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Caoimhin S Griffin
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Roddy J Large
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Gerard P Sergeant
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Mark A Hollywood
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Noel G McHale
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Keith D Thornbury
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
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Oxidation of RyR2 Has a Biphasic Effect on the Threshold for Store Overload-Induced Calcium Release. Biophys J 2017; 110:2386-2396. [PMID: 27276257 DOI: 10.1016/j.bpj.2016.04.036] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Revised: 03/17/2016] [Accepted: 04/08/2016] [Indexed: 01/14/2023] Open
Abstract
At the single-channel level, oxidation of the cardiac ryanodine receptor (RyR2) is known to activate and inhibit the channel depending on the level of oxidation. However, the mechanisms through which these changes alter the activity of RyR2 in a cellular setting are poorly understood. In this study, we determined the effect of oxidation on a common form of RyR2 regulation; store overload-induced Ca(2+) release (SOICR). We found that oxidation resulted in concentration and time-dependent changes in the activation threshold for SOICR. Low concentrations of the oxidant H2O2 resulted in a decrease in the threshold for SOICR, which led to an increase in SOICR events. However, higher concentrations of H2O2, or prolonged exposure, reversed these changes and led to an increase in the threshold for SOICR. This increase in the threshold for SOICR in most cells was to such an extent that it led to the complete inhibition of SOICR. Acute exposure to high concentrations of H2O2 led to an initial decrease and then increase in the threshold for SOICR. In the majority of cells the increased threshold could not be reversed by the application of the reducing agent dithiothreitol. Therefore, our data suggest that low levels of RyR2 oxidation increase the channel activity by decreasing the threshold for SOICR, whereas high levels of RyR2 oxidation irreversibly increase the threshold for SOICR leading to an inhibition of RyR2. Combined, this indicates that oxidation regulates RyR2 by the same mechanism as phosphorylation, methylxanthines, and mutations, via changes in the threshold for SOICR.
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Strege PR, Gibbons SJ, Mazzone A, Bernard CE, Beyder A, Farrugia G. EAVK segment "c" sequence confers Ca 2+-dependent changes to the kinetics of full-length human Ano1. Am J Physiol Gastrointest Liver Physiol 2017; 312:G572-G579. [PMID: 28336549 PMCID: PMC5495914 DOI: 10.1152/ajpgi.00429.2016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 03/07/2017] [Accepted: 03/15/2017] [Indexed: 01/31/2023]
Abstract
Anoctamin1 (Ano1 and TMEM16A) is a calcium-activated chloride channel specifically expressed in the interstitial cells of Cajal (ICC) of the gastrointestinal tract muscularis propria. Ano1 is necessary for normal electrical slow waves and ICC proliferation. The full-length human Ano1 sequence includes an additional exon, exon "0," at the NH2 terminus. Ano1 with exon 0 [Ano1(0)] had a lower EC50 for intracellular calcium ([Ca2+]i) and faster chloride current (ICl) kinetics. The Ano1 alternative splice variant with segment "c" encoding exon 13 expresses on the first intracellular loop four additional amino acid residues, EAVK, which alter ICl at low [Ca2+]i Exon 13 is expressed in 75-100% of Ano1 transcripts in most human tissues but only 25% in the human stomach. Our aim was to determine the effect of EAVK deletion on Ano1(0)ICl parameters. By voltage-clamp electrophysiology, we examined ICl in HEK293 cells transiently expressing Ano1(0) with or without the EAVK sequence [Ano1(0)ΔEAVK]. The EC50 values of activating and deactivating ICl for [Ca2+]i were 438 ± 7 and 493 ± 9 nM for Ano1(0) but higher for Ano1(0)ΔEAVK at 746 ± 47 and 761 ± 26 nM, respectively. Meanwhile, the EC50 values for the ratio of instantaneous to steady-state ICl were not different between variants. Congruently, the time constant of activation was slower for Ano1(0)ΔEAVK than Ano1(0) currents at intermediate [Ca2+]i These results suggest that EAVK decreases the calcium sensitivity of Ano1(0) current activation and deactivation by slowing activation kinetics. Differential expression of EAVK in the human stomach may function as a switch to increase sensitivity to [Ca2+]i via faster gating of Ano1.NEW & NOTEWORTHY Calcium-activated chloride channel anoctamin1 (Ano1) is necessary for normal slow waves in the gastrointestinal interstitial cells of Cajal. Exon 0 encodes the NH2 terminus of full-length human Ano1 [Ano1(0)], while exon 13 encodes residues EAVK on its first intracellular loop. Splice variants lack EAVK more often in the stomach than other tissues. Ano1(0) without EAVK [Ano1(0)ΔEAVK] has reduced sensitivity for intracellular calcium, attributable to slower kinetics. Differential expression of EAVK may function as a calcium-sensitive switch in the human stomach.
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60
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Kamaleddin MA. Molecular, biophysical, and pharmacological properties of calcium-activated chloride channels. J Cell Physiol 2017; 233:787-798. [PMID: 28121009 DOI: 10.1002/jcp.25823] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 01/24/2017] [Indexed: 12/15/2022]
Abstract
Calcium-activated chloride channels (CaCCs) are a family of anionic transmembrane ion channels. They are mainly responsible for the movement of Cl- and other anions across the biological membranes, and they are widely expressed in different tissues. Since the Cl- flow into or out of the cell plays a crucial role in hyperpolarizing or depolarizing the cells, respectively, the impact of intracellular Ca2+ concentration on these channels is attracting a lot of attentions. After summarizing the molecular, biophysical, and pharmacological properties of CaCCs, the role of CaCCs in normal cellular functions will be discussed, and I will emphasize how dysregulation of CaCCs in pathological conditions can account for different diseases. A better understanding of CaCCs and a pivotal regulatory role of Ca2+ can shed more light on the therapeutic strategies for different neurological disorders that arise from chloride dysregulation, such as asthma, cystic fibrosis, and neuropathic pain.
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Affiliation(s)
- Mohammad Amin Kamaleddin
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada.,Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, Ontario, Canada
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Abstract
UNLABELLED Transmembrane protein 16A (TMEM16A) regulates a wide variety of cellular activities, including epithelial fluid secretion and maintenance of ion homeostasis. Lipopolysaccharide (LPS), an outer membrane component of Gram-negative bacteria, is one of the major causes of acute lung injury (ALI). In this study, we investigated the effects of LPS on the expression of TMEM16A in LA795 cells and mouse lung tissue and the potential mechanism. RESULT We detected the expression of TMEM16A in LA795 cells and mouse lung tissue by RT-PCR, Western blot, and RNA interference techniques. TMEM16A expression was significantly increased by LPS stimulation in LA795 cells and in mouse lung tissue. Moreover, the LPS-induced TMEM16A expression enhancement in lung tissue was much more prominent in the alveolar epithelial region than in bigger airway epithelial cells. The typical TMEM16A current was recorded, and LPS treatment significantly enhances the current amplitude in LA795 cells. TMEM16A shRNA or TMEM16A inhibitor (T16Ainh-A01) did not affect alveolar fluid clearance (AFC), while co-application of T16Ainh-A01 induced a stronger AFC inhibition than LPS alone. LPS notably and synchronously enhanced Akt phosphorylation (p-Akt) and TMEM16A expression in a time-dependent manner in LA795 cells. Taken together, our results suggest that TMEM16A maybe plays an important role in pathological conditions of LPS-induced ALI as a protective protein.
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Ha GE, Lee J, Kwak H, Song K, Kwon J, Jung SY, Hong J, Chang GE, Hwang EM, Shin HS, Lee CJ, Cheong E. The Ca 2+-activated chloride channel anoctamin-2 mediates spike-frequency adaptation and regulates sensory transmission in thalamocortical neurons. Nat Commun 2016; 7:13791. [PMID: 27991499 PMCID: PMC5187435 DOI: 10.1038/ncomms13791] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 11/02/2016] [Indexed: 12/22/2022] Open
Abstract
Neuronal firing patterns, which are crucial for determining the nature of encoded information, have been widely studied; however, the molecular identity and cellular mechanisms of spike-frequency adaptation are still not fully understood. Here we show that spike-frequency adaptation in thalamocortical (TC) neurons is mediated by the Ca2+-activated Cl− channel (CACC) anoctamin-2 (ANO2). Knockdown of ANO2 in TC neurons results in significantly reduced spike-frequency adaptation along with increased tonic spiking. Moreover, thalamus-specific knockdown of ANO2 increases visceral pain responses. These results indicate that ANO2 contributes to reductions in spike generation in highly activated TC neurons and thereby restricts persistent information transmission.
Spike-frequency adaptation in thalamocortical (TC) neurons is important for sensory transmission though the underlying mechanisms are not fully understood. Here, the authors identify a role for the calcium-activated chloride channel, ANO2, in mediating TC spiking adaptations and visceral pain response.
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Affiliation(s)
- Go Eun Ha
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, Republic of Korea
| | - Jaekwang Lee
- Center for Neural Science, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
| | - Hankyul Kwak
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, Republic of Korea
| | - Kiyeong Song
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, Republic of Korea
| | - Jea Kwon
- Center for Neural Science, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
| | - Soon-Young Jung
- Center for Neural Science, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
| | - Joohyeon Hong
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, Republic of Korea
| | - Gyeong-Eon Chang
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, Republic of Korea
| | - Eun Mi Hwang
- Center for Functional Connectomics, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
| | - Hee-Sup Shin
- Center for Cognition and Sociality, Institute for Basic Science, Daejeon 34141, Republic of Korea
| | - C Justin Lee
- Center for Neural Science, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
| | - Eunji Cheong
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, Republic of Korea
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63
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Kamikawa A, Ichii O, Sakazaki J, Ishikawa T. Ca2+-activated Cl− channel currents in mammary secretory cells from lactating mouse. Am J Physiol Cell Physiol 2016; 311:C808-C819. [DOI: 10.1152/ajpcell.00050.2016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 08/19/2016] [Indexed: 11/22/2022]
Abstract
The Cl− secretion via Ca2+-activated Cl− channel (CaCC) is critical for fluid secretion in exocrine glands like the salivary gland. Also in the mammary gland, it has been hypothesized that CaCC plays an important role in the secretion of Cl− and aqueous phase of milk. However, there has been no evidence for the functional expression of CaCC in native mammary secretory (MS) cells of lactating animals. We therefore assessed membrane current in MS cells that were freshly isolated from lactating mice using whole cell patch-clamp techniques. In MS cells, we detected CaCC current that exhibited the following characteristics: 1) Ca2+-dependent activation at the concentrations of submicromolar range; 2) voltage-dependent activation; 3) slow kinetics for activation and deactivation; 4) outward rectification of the steady-state current; 5) anion permeability in the sequence of I− > NO3− > Br− > Cl− >> glutamate; 6) inhibition by Cl− channel blockers (niflumic acid, DIDS, and CaCCinh-A01). These characteristics of native CaCC current were similar to reported characteristics of heterologously expressed TMEM16A. RT-PCR analyses showed the expression of multiple CaCC channels including TMEM16A, Best1, and Best3 in the mammary glands of lactating mice. Immunohistochemical staining revealed the localization of TMEM16A protein at the apical membrane of the MS cells. Collectively, our data strongly suggest that MS cells functionally express CaCC, which is at least partly constituted by TMEM16A. The CaCC such as TMEM16A at the apical membrane of the MS cells may influence the quantity and/or quality of milk.
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Affiliation(s)
- Akihiro Kamikawa
- Department of Basic Veterinary Medicine, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Japan; and
| | - Osamu Ichii
- Laboratory of Anatomy, Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Junpei Sakazaki
- Department of Basic Veterinary Medicine, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Japan; and
| | - Toru Ishikawa
- Department of Basic Veterinary Medicine, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Japan; and
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64
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Ma K, Wang H, Yu J, Wei M, Xiao Q. New Insights on the Regulation of Ca 2+ -Activated Chloride Channel TMEM16A. J Cell Physiol 2016; 232:707-716. [PMID: 27682822 DOI: 10.1002/jcp.25621] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Accepted: 09/27/2016] [Indexed: 12/16/2022]
Abstract
TMEM16A, also known as anoctamin 1, is a recently identified Ca2+ -activated chloride channel and the first member of a 10-member TMEM16 family. TMEM16A dysfunction is implicated in many diseases such as cancer, hypertension, and cystic fibrosis. TMEM16A channels are well known to be dually regulated by voltage and Ca2+ . In addition, recent studies have revealed that TMEM16A channels are regulated by many molecules such as calmodulin, protons, cholesterol, and phosphoinositides, and a diverse range of stimuli such as thermal and mechanical stimuli. A better understanding of the regulatory mechanisms of TMEM16A is important to understand its physiological and pathological role. Recently, the crystal structure of a TMEM16 family member from the fungus Nectria haematococcaten (nhTMEM16) is discovered, and provides valuable information for studying the structure and function of TMEM16A. In this review, we discuss the structure and function of TMEM16A channels based on the crystal structure of nhTMEM16A and focus on the regulatory mechanisms of TMEM16A channels. J. Cell. Physiol. 232: 707-716, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Ke Ma
- Department of Ion Channel Pharmacology, School of Pharmacy, China Medical University, Shenyang, P. R. China
| | - Hui Wang
- Department of Ion Channel Pharmacology, School of Pharmacy, China Medical University, Shenyang, P. R. China
| | - Jiankun Yu
- Department of Ion Channel Pharmacology, School of Pharmacy, China Medical University, Shenyang, P. R. China
| | - Minjie Wei
- Department of Pharmacology, School of Pharmacy, China Medical University, Shenyang, P. R. China
| | - Qinghuan Xiao
- Department of Ion Channel Pharmacology, School of Pharmacy, China Medical University, Shenyang, P. R. China
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65
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Boedtkjer E, Matchkov VV, Boedtkjer DMB, Aalkjaer C. Negative News: Cl− and HCO3− in the Vascular Wall. Physiology (Bethesda) 2016; 31:370-83. [DOI: 10.1152/physiol.00001.2016] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Cl− and HCO3− are the most prevalent membrane-permeable anions in the intra- and extracellular spaces of the vascular wall. Outwardly directed electrochemical gradients for Cl− and HCO3− permit anion channel opening to depolarize vascular smooth muscle and endothelial cells. Transporters and channels for Cl− and HCO3− also modify vascular contractility and structure independently of membrane potential. Transport of HCO3− regulates intracellular pH and thereby modifies the activity of enzymes, ion channels, and receptors. There is also evidence that Cl− and HCO3− transport proteins affect gene expression and protein trafficking. Considering the extensive implications of Cl− and HCO3− in the vascular wall, it is critical to understand how these ions are transported under physiological conditions and how disturbances in their transport can contribute to disease development. Recently, sensing mechanisms for Cl− and HCO3− have been identified in the vascular wall where they modify ion transport and vasomotor function, for instance, during metabolic disturbances. This review discusses current evidence that transport (e.g., via NKCC1, NBCn1, Ca2+-activated Cl− channels, volume-regulated anion channels, and CFTR) and sensing (e.g., via WNK and RPTPγ) of Cl− and HCO3− influence cardiovascular health and disease.
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Affiliation(s)
| | | | - Donna M. B. Boedtkjer
- Department of Biomedicine, Aarhus University, Denmark
- Department of Clinical Medicine, Aarhus University, Denmark; and
| | - Christian Aalkjaer
- Department of Biomedicine, Aarhus University, Denmark
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
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66
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Han Y, Shewan AM, Thorn P. HCO3- Transport through Anoctamin/Transmembrane Protein ANO1/TMEM16A in Pancreatic Acinar Cells Regulates Luminal pH. J Biol Chem 2016; 291:20345-52. [PMID: 27510033 DOI: 10.1074/jbc.m116.750224] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Indexed: 02/01/2023] Open
Abstract
The identification of ANO1/TMEM16A as the likely calcium-dependent chloride channel of exocrine glands has led to a more detailed understanding of its biophysical properties. This includes a calcium-dependent change in channel selectivity and evidence that HCO3 (-) permeability can be significant. Here we use freshly isolated pancreatic acini that preserve the luminal structure to measure intraluminal pH and test the idea that ANO1/TMEM16A contributes to luminal pH balance. Our data show that, under physiologically relevant stimulation with 10 pm cholesystokinin, the luminal acid load that results from the exocytic fusion of zymogen granules is significantly blunted by HCO3 (-) buffer in comparison with HEPES, and that this is blocked by the specific TMEM16A inhibitor T16inh-A01. Furthermore, in a model of acute pancreatitis, we observed substantive luminal acidification and provide evidence that ANO1/TMEM16A acts to attenuate this pH shift. We conclude that ANO1/TMEM16A is a significant pathway in pancreatic acinar cells for HCO3 (-) secretion into the lumen.
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Affiliation(s)
| | - Annette M Shewan
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland 4072, Australia and
| | - Peter Thorn
- From the School of Biomedical Sciences and the Charles Perkins Centre, John Hopkins Drive, University of Sydney, Sydney, New South Wales 2050, Australia
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67
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Sung TS, O'Driscoll K, Zheng H, Yapp NJ, Leblanc N, Koh SD, Sanders KM. Influence of intracellular Ca2+ and alternative splicing on the pharmacological profile of ANO1 channels. Am J Physiol Cell Physiol 2016; 311:C437-51. [PMID: 27413167 DOI: 10.1152/ajpcell.00070.2016] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Accepted: 07/09/2016] [Indexed: 11/22/2022]
Abstract
Anoctamin-1 (ANO1) is a Ca(2+)-activated Cl(-) channel expressed in many types of cells. Splice variants of ANO1 have been shown to influence the biophysical properties of conductance. It has been suggested that several new antagonists of ANO1 with relatively high affinity and selectivity might be useful for experimental and, potentially, therapeutic purposes. We investigated the effects of intracellular Ca(2+) concentration ([Ca(2+)]i) at 100-1,000 nM, a concentration range that might be achieved in cells during physiological activation of ANO1 channels, on blockade of ANO1 channels expressed in HEK-293 cells. Whole cell and excised patch configurations of the patch-clamp technique were used to perform tests on a variety of naturally occurring splice variants of ANO1. Blockade of ANO1 currents with aminophenylthiazole (T16Ainh-A01) was highly dependent on [Ca(2+)]i Increasing [Ca(2+)]i reduced the potency of this blocker. Similar Ca(2+)-dependent effects were also observed with benzbromarone. Experiments on excised, inside-out patches showed that the diminished potency of the blockers caused by intracellular Ca(2+) might involve a competitive interaction for a common binding site or repulsion of the blocking drugs by electrostatic forces at the cytoplasmic surface of the channels. The degree of interaction between the channel blockers and [Ca(2+)]i depends on the splice variant expressed. These experiments demonstrate that the efficacy of ANO1 antagonists depends on [Ca(2+)]i, suggesting a need for caution when ANO1 blockers are used to determine the role of ANO1 in physiological functions and in their use as therapeutic agents.
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Affiliation(s)
- Tae Sik Sung
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada; and
| | - Kate O'Driscoll
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada; and
| | - Haifeng Zheng
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada; and
| | - Nicholas J Yapp
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada; and
| | - Normand Leblanc
- Department of Pharmacology, Center for Cardiovascular Research, University of Nevada School of Medicine, Reno, Nevada
| | - Sang Don Koh
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada; and
| | - Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada; and
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68
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Ishihara K, Suzuki J, Nagata S. Role of Ca(2+) in the Stability and Function of TMEM16F and 16K. Biochemistry 2016; 55:3180-8. [PMID: 27227820 DOI: 10.1021/acs.biochem.6b00176] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
There are 10 transmembrane protein (TMEM) 16-family proteins in humans and mice. Among them, TMEM16F acts as a Ca(2+)-dependent phospholipid scramblase at the plasma membrane. However, how Ca(2+) activates TMEM16F's phospholipid-scramblase activity has not been elucidated. Here we found that in the presence of Ca(2+), TMEM16K (whose function is unknown) directly binds Ca(2+) to form a stable complex that can be detected by blue-native polyacrylamide gel electrophoresis. In the absence of Ca(2+), TMEM16K and TMEM16F aggregated, suggesting that their structure is stabilized by Ca(2+). Comprehensive mutagenesis of acidic residues in TMEM16K's cytoplasmic and transmembrane regions identified five residues that are critical for binding Ca(2+). These residues were well conserved between TMEM16F and 16K, and point mutations of these residues in TMEM16F reduced its ability to support Ca(2+)-dependent phospholipid scrambling. Our results suggest that Ca(2+) binds TMEM16F directly and induces conformational changes that support its stability and function.
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Affiliation(s)
- Kenji Ishihara
- Biochemistry & Immunology, Immunology Frontier Research Center, Osaka University , 3-1 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Jun Suzuki
- Biochemistry & Immunology, Immunology Frontier Research Center, Osaka University , 3-1 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Shigekazu Nagata
- Biochemistry & Immunology, Immunology Frontier Research Center, Osaka University , 3-1 Yamada-oka, Suita, Osaka 565-0871, Japan
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69
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Shah VS, Meyerholz DK, Tang XX, Reznikov L, Abou Alaiwa M, Ernst SE, Karp PH, Wohlford-Lenane CL, Heilmann KP, Leidinger MR, Allen PD, Zabner J, McCray PB, Ostedgaard LS, Stoltz DA, Randak CO, Welsh MJ. Airway acidification initiates host defense abnormalities in cystic fibrosis mice. Science 2016; 351:503-7. [PMID: 26823428 DOI: 10.1126/science.aad5589] [Citation(s) in RCA: 227] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Cystic fibrosis (CF) is caused by mutations in the gene that encodes the cystic fibrosis transmembrane conductance regulator (CFTR) anion channel. In humans and pigs, the loss of CFTR impairs respiratory host defenses, causing airway infection. But CF mice are spared. We found that in all three species, CFTR secreted bicarbonate into airway surface liquid. In humans and pigs lacking CFTR, unchecked H(+) secretion by the nongastric H(+)/K(+) adenosine triphosphatase (ATP12A) acidified airway surface liquid, which impaired airway host defenses. In contrast, mouse airways expressed little ATP12A and secreted minimal H(+); consequently, airway surface liquid in CF and non-CF mice had similar pH. Inhibiting ATP12A reversed host defense abnormalities in human and pig airways. Conversely, expressing ATP12A in CF mouse airways acidified airway surface liquid, impaired defenses, and increased airway bacteria. These findings help explain why CF mice are protected from infection and nominate ATP12A as a potential therapeutic target for CF.
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Affiliation(s)
- Viral S Shah
- Department of Medicine, University of Iowa, Iowa City, IA 52242, USA. Department of Molecular Physiology and Biophysics, Pappajohn Biomedical Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - David K Meyerholz
- Department of Pathology, University of Iowa, Iowa City, IA 52242, USA
| | - Xiao Xiao Tang
- Department of Medicine, University of Iowa, Iowa City, IA 52242, USA. Howard Hughes Medical Institute, University of Iowa, Iowa City, IA 52242, USA
| | - Leah Reznikov
- Department of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | | | - Sarah E Ernst
- Department of Medicine, University of Iowa, Iowa City, IA 52242, USA. Howard Hughes Medical Institute, University of Iowa, Iowa City, IA 52242, USA
| | - Philip H Karp
- Department of Medicine, University of Iowa, Iowa City, IA 52242, USA. Howard Hughes Medical Institute, University of Iowa, Iowa City, IA 52242, USA
| | | | | | | | - Patrick D Allen
- Department of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Joseph Zabner
- Department of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Paul B McCray
- Department of Pediatrics University of Iowa, Iowa City, IA 52242, USA. Department of Microbiology, University of Iowa, Iowa City, IA 52242, USA
| | | | - David A Stoltz
- Department of Medicine, University of Iowa, Iowa City, IA 52242, USA. Department of Molecular Physiology and Biophysics, Pappajohn Biomedical Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA. Department of Biomedical Engineering, College of Engineering, University of Iowa, Iowa City, IA 52242, USA
| | | | - Michael J Welsh
- Department of Medicine, University of Iowa, Iowa City, IA 52242, USA. Department of Molecular Physiology and Biophysics, Pappajohn Biomedical Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA. Howard Hughes Medical Institute, University of Iowa, Iowa City, IA 52242, USA
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70
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Jun I, Cheng MH, Sim E, Jung J, Suh BL, Kim Y, Son H, Park K, Kim CH, Yoon JH, Whitcomb DC, Bahar I, Lee MG. Pore dilatation increases the bicarbonate permeability of CFTR, ANO1 and glycine receptor anion channels. J Physiol 2016; 594:2929-55. [PMID: 26663196 DOI: 10.1113/jp271311] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2015] [Accepted: 12/06/2015] [Indexed: 01/30/2023] Open
Abstract
KEY POINTS Cellular stimuli can modulate the ion selectivity of some anion channels, such as CFTR, ANO1 and the glycine receptor (GlyR), by changing pore size. Ion selectivity of CFTR, ANO1 and GlyR is critically affected by the electric permittivity and diameter of the channel pore. Pore size change affects the energy barriers of ion dehydration as well as that of size-exclusion of anion permeation. Pore dilatation increases the bicarbonate permeability (P HC O3/ Cl ) of CFTR, ANO1 and GlyR. Dynamic change in P HC O3/ Cl may mediate many physiological and pathological processes. ABSTRACT Chloride (Cl(-) ) and bicarbonate (HCO3 (-) ) are two major anions and their permeation through anion channels plays essential roles in our body. However, the mechanism of ion selection by the anion channels is largely unknown. Here, we provide evidence that pore dilatation increases the bicarbonate permeability (P HC O3/ Cl ) of anion channels by reducing energy barriers of size-exclusion and ion dehydration of HCO3 (-) permeation. Molecular, physiological and computational analyses of major anion channels, such as cystic fibrosis transmembrane conductance regulator (CFTR), anoctamin-1(ANO1/TMEM16A) and the glycine receptor (GlyR), revealed that the ion selectivity of anion channels is basically determined by the electric permittivity and diameter of the pore. Importantly, cellular stimuli dynamically modulate the anion selectivity of CFTR and ANO1 by changing the pore size. In addition, pore dilatation by a mutation in the pore-lining region alters the anion selectivity of GlyR. Changes in pore size affected not only the energy barriers of size exclusion but that of ion dehydration by altering the electric permittivity of water-filled cavity in the pore. The dynamic increase in P HC O3/ Cl by pore dilatation may have many physiological and pathophysiological implications ranging from epithelial HCO3 (-) secretion to neuronal excitation.
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Affiliation(s)
- Ikhyun Jun
- Department of Pharmacology, Brain Korea 21 PLUS Project for Medical Sciences, Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, 120-752, Korea.,Department of Ophthalmology, Yonsei University College of Medicine, Seoul, 120-752, Korea
| | - Mary Hongying Cheng
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Eunji Sim
- Department of Chemistry, Yonsei University College of Science, Seoul, 120-749, Korea
| | - Jinsei Jung
- Department of Pharmacology, Brain Korea 21 PLUS Project for Medical Sciences, Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, 120-752, Korea.,Department of Otorhinolaryngology, Yonsei University College of Medicine, Seoul, 120-752, Korea
| | - Bong Lim Suh
- Department of Chemistry, Yonsei University College of Science, Seoul, 120-749, Korea
| | - Yonjung Kim
- Department of Pharmacology, Brain Korea 21 PLUS Project for Medical Sciences, Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, 120-752, Korea
| | - Hankil Son
- Department of Pharmacology, Brain Korea 21 PLUS Project for Medical Sciences, Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, 120-752, Korea
| | - Kyungsoo Park
- Department of Pharmacology, Brain Korea 21 PLUS Project for Medical Sciences, Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, 120-752, Korea
| | - Chul Hoon Kim
- Department of Pharmacology, Brain Korea 21 PLUS Project for Medical Sciences, Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, 120-752, Korea
| | - Joo-Heon Yoon
- Department of Otorhinolaryngology, Yonsei University College of Medicine, Seoul, 120-752, Korea
| | - David C Whitcomb
- Department of Medicine, Division of Gastroenterology, Hepatology and Nutrition, University of Pittsburgh, Pittsburgh, PA, USA
| | - Ivet Bahar
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Min Goo Lee
- Department of Pharmacology, Brain Korea 21 PLUS Project for Medical Sciences, Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, 120-752, Korea
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71
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Dutta AK, Khimji AK, Liu S, Karamysheva Z, Fujita A, Kresge C, Rockey DC, Feranchak AP. PKCα regulates TMEM16A-mediated Cl⁻ secretion in human biliary cells. Am J Physiol Gastrointest Liver Physiol 2016; 310:G34-42. [PMID: 26542395 PMCID: PMC4698437 DOI: 10.1152/ajpgi.00146.2015] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Accepted: 10/31/2015] [Indexed: 02/07/2023]
Abstract
TMEM16A is a newly identified Ca(2+)-activated Cl(-) channel in biliary epithelial cells (BECs) that is important in biliary secretion. While extracellular ATP stimulates TMEM16A via binding P2 receptors and increasing intracellular Ca(2+) concentration ([Ca(2+)]i), the regulatory pathways have not been elucidated. Protein kinase C (PKC) contributes to ATP-mediated secretion in BECs, although its potential role in TMEM16A regulation is unknown. To determine whether PKCα regulates the TMEM16A-dependent membrane Cl(-) transport in BECs, studies were performed in human biliary Mz-cha-1 cells. Addition of extracellular ATP induced a rapid translocation of PKCα from the cytosol to the plasma membrane and activation of whole cell Ca(2+)-activated Cl(-) currents. Currents demonstrated outward rectification and reversal at 0 mV (properties consistent with TMEM16A) and were inhibited by either molecular (siRNA) or pharmacologic (PMA or Gö6976) inhibition of PKCα. Intracellular dialysis with recombinant PKCα activated Cl(-) currents with biophysical properties identical to TMEM16A in control cells but not in cells after transfection with TMEM16A siRNA. In conclusion, our studies demonstrate that PKCα is coupled to ATP-stimulated TMEM16A activation in BECs. Targeting this ATP-Ca(2+)-PKCα signaling pathway may represent a therapeutic strategy to increase biliary secretion and promote bile formation.
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Affiliation(s)
- Amal K. Dutta
- 1Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas;
| | | | - Songling Liu
- 4Department of Internal Medicine, Medical University of South Carolina, Charleston, South Carolina
| | - Zemfira Karamysheva
- 3Department of Physiology, University of Texas Southwestern Medical Center, Dallas, Texas; and
| | - Akiko Fujita
- 2Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas;
| | - Charles Kresge
- 1Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas;
| | - Don C. Rockey
- 4Department of Internal Medicine, Medical University of South Carolina, Charleston, South Carolina
| | - Andrew P. Feranchak
- 1Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas;
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Modulating Ca²⁺ signals: a common theme for TMEM16, Ist2, and TMC. Pflugers Arch 2015; 468:475-90. [PMID: 26700940 DOI: 10.1007/s00424-015-1767-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 11/24/2015] [Accepted: 11/26/2015] [Indexed: 12/21/2022]
Abstract
Since the discovery of TMEM16A (anoctamin 1, ANO1) as Ca(2+)-activated Cl(-) channel, the protein was found to serve different physiological functions, depending on the type of tissue. Subsequent reports on other members of the anoctamin family demonstrated a broad range of yet poorly understood properties. Compromised anoctamin function is causing a wide range of diseases, such as hearing loss (ANO2), bleeding disorder (ANO6), ataxia and dystonia (ANO3, 10), persistent borrelia and mycobacteria infection (ANO10), skeletal syndromes like gnathodiaphyseal dysplasia and limb girdle muscle dystrophy (ANO5), and cancer (ANO1, 6, 7). Animal models demonstrate CF-like airway disease, asthma, and intestinal hyposecretion (ANO1). Although present data indicate that ANO1 is a Ca(2+)-activated Cl(-) channel, it remains unclear whether all anoctamins form plasma membrane-localized or intracellular chloride channels. We find Ca(2+)-activated Cl(-) currents appearing by expression of most anoctamin paralogs, including the Nectria haematococca homologue nhTMEM16 and the yeast homologue Ist2. As recent studies show a role of anoctamins, Ist2, and the related transmembrane channel-like (TMC) proteins for intracellular Ca(2+) signaling, we will discuss the role of these proteins in generating compartmentalized Ca(2+) signals, which may give a hint as to the broad range of cellular functions of anoctamins.
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73
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Novel Roles for Chloride Channels, Exchangers, and Regulators in Chronic Inflammatory Airway Diseases. Mediators Inflamm 2015; 2015:497387. [PMID: 26612971 PMCID: PMC4647060 DOI: 10.1155/2015/497387] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 10/13/2015] [Indexed: 01/14/2023] Open
Abstract
Chloride transport proteins play critical roles in inflammatory airway diseases, contributing to the detrimental aspects of mucus overproduction, mucus secretion, and airway constriction. However, they also play crucial roles in contributing to the innate immune properties of mucus and mucociliary clearance. In this review, we focus on the emerging novel roles for a chloride channel regulator (CLCA1), a calcium-activated chloride channel (TMEM16A), and two chloride exchangers (SLC26A4/pendrin and SLC26A9) in chronic inflammatory airway diseases.
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74
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Strege PR, Bernard CE, Mazzone A, Linden DR, Beyder A, Gibbons SJ, Farrugia G. A novel exon in the human Ca2+-activated Cl- channel Ano1 imparts greater sensitivity to intracellular Ca2. Am J Physiol Gastrointest Liver Physiol 2015; 309:G743-9. [PMID: 26359375 PMCID: PMC4628966 DOI: 10.1152/ajpgi.00074.2015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 09/06/2015] [Indexed: 01/31/2023]
Abstract
Anoctamin 1 (Ano1; TMEM16A) is a Ca(2+)-activated Cl(-) channel (CACC) expressed in interstitial cells of Cajal. The mechanisms by which Ca(2+) regulates Ano1 are incompletely understood. In the gastrointestinal tract, Ano1 is required for normal slow wave activity and is involved in regulating cell proliferation. Splice variants of Ano1 have varying electrophysiological properties and altered expression in disease states. Recently, we identified a transcript for human Ano1 containing a novel exon-"exon 0" upstream of and in frame with exon 1. The electrophysiological properties of this longer Ano1 isoform are unknown. Our aim was to determine the functional contribution of the newly identified exon to the Ca(2+) sensitivity and electrophysiological properties of Ano1. Constructs with [Ano1(+0)] or without [Ano1(-0)] the newly identified exon were transfected into human embryonic kidney-293 cells. Voltage-clamp electrophysiology was used to determine voltage- and time-dependent parameters of whole cell Cl(-) currents between isoforms with varying concentrations of intracellular Ca(2+), extracellular anions, or Cl(-) channel inhibitors. We found that exon 0 did not change voltage sensitivity and had no impact on the relative permeability of Ano1 to most anions. Ano1(+0) exhibited greater changes in current density but lesser changes in kinetics than Ano1(-0) in response to varying intracellular Ca(2+). The CACC inhibitor niflumic acid inhibited current with greater efficacy and higher potency against Ano1(+0) compared with Ano1(-0). Likewise, the Ano1 inhibitor T16Ainh-A01 reduced Ano1(+0) more than Ano1(-0). In conclusion, human Ano1 containing exon 0 imparts its Cl(-) current with greater sensitivity to intracellular Ca(2+) and CACC inhibitors.
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Chun H, Cho H, Choi J, Lee J, Kim SM, Kim H, Oh U. Protons inhibit anoctamin 1 by competing with calcium. Cell Calcium 2015; 58:431-41. [DOI: 10.1016/j.ceca.2015.06.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Revised: 06/13/2015] [Accepted: 06/28/2015] [Indexed: 01/30/2023]
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76
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Abstract
The human exocrine pancreas consists of 2 main cell types: acinar and ductal cells. These exocrine cells interact closely to contribute to the secretion of pancreatic juice. The most important ion in terms of the pancreatic ductal secretion is HCO3. In fact, duct cells produce an alkaline fluid that may contain up to 140 mM NaHCO3, which is essential for normal digestion. This article provides an overview of the basics of pancreatic ductal physiology and pathophysiology. In the first part of the article, we discuss the ductal electrolyte and fluid transporters and their regulation. The central role of cystic fibrosis transmembrane conductance regulator (CFTR) is highlighted, which is much more than just a Cl channel. We also review the role of pancreatic ducts in severe debilitating diseases such as cystic fibrosis (caused by various genetic defects of cftr), pancreatitis, and diabetes mellitus. Stimulation of ductal secretion in cystic fibrosis and pancreatitis may have beneficial effects in their treatment.
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77
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Kim HJ, Jun I, Yoon JS, Jung J, Kim YK, Kim WK, Kim BJ, Song J, Kim SJ, Nam JH, Lee MG. Selective serotonin reuptake inhibitors facilitate ANO6 (TMEM16F) current activation and phosphatidylserine exposure. Pflugers Arch 2015; 467:2243-56. [PMID: 25630304 DOI: 10.1007/s00424-015-1692-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Revised: 01/15/2015] [Accepted: 01/16/2015] [Indexed: 11/30/2022]
Abstract
Anoctamin 6 (ANO6) is a member of the recently identified TMEM16/anoctamin protein family comprising Ca(2+)-activated Cl(-) channels that generate outward-rectifying ionic currents in response to intracellular Ca(2+) increase. ANO6 is also essential for Ca(2+)-dependent phospholipid scrambling required for blood coagulation. Selective serotonin reuptake inhibitors (SSRIs)--fluoxetine, sertraline, and paroxetine-that are used for the treatment of major depressive disorders can increase the risk of upper gastrointestinal bleeding after chronic treatment. However, at the earlier stage of intake, which is 1-7 days after the treatment, the possibility of blood coagulation might also increase, but transiently. Therefore, in this study, we investigated whether therapeutic SSRI concentrations affected the Cl(-) current or phospholipid scrambling activity of ANO6 by assessing ANO6 currents (I ANO6), phosphatidylserine (PS) exposure, and platelet aggregation. In the whole-cell patch mode, SSRIs facilitated Ca(2+)-dependent activation of IANO6 in ANO6-transfected cells, as evidenced by a significant decrease in the delay of IANO6 generation. On the other hand, in the inside-out patch clamp configuration, SSRIs showed an inhibitory effect on ANO6 currents, suggesting that SSRIs activate ANO6 via an indirect mechanism in intact cells. SSRIs also facilitated Ca(2+)-dependent PS exposure and α-thrombin-induced platelet aggregation. These results indicate that SSRIs at clinically relevant concentrations promote Ca(2+)-dependent activation of ANO6, which may have potential clinical implications such as the underlying mechanism of SSRI-induced adverse drug reactions.
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Affiliation(s)
- Hyun Jong Kim
- Department of Physiology, Dongguk University College of Medicine, 123 Dongdae-ro, Kyungju, 780-714, Republic of Korea
| | - Ikhyun Jun
- Department of Pharmacology, BK21 PLUS Project for Medical Sciences, Yonsei University College of Medicine, 50 Yonsei-ro, Seodaemun-gu, Seoul, 120-752, Republic of Korea
| | - Jae Seok Yoon
- Biochemistry and Molecular Biology, Oregon Health Sciences University, 3181 SW Sam Jackson Park Road, Portland, OR, 97239, USA
| | - Jinsei Jung
- Department of Pharmacology, BK21 PLUS Project for Medical Sciences, Yonsei University College of Medicine, 50 Yonsei-ro, Seodaemun-gu, Seoul, 120-752, Republic of Korea
| | - Yung Kyu Kim
- Department of Physiology, Dongguk University College of Medicine, 123 Dongdae-ro, Kyungju, 780-714, Republic of Korea
| | - Woo Kyung Kim
- Channelopathy Research Center (CRC), Dongguk University College of Medicine, 27 Dongguk-ro, Ilsan Dong-gu, Goyang, 410-773, Republic of Korea
- Department of Internal Medicine Graduate School of Medicine, Dongguk University, 27 Dongguk-ro, Ilsan Dong-gu, Goyang, 410-773, Republic of Korea
| | - Byung Joo Kim
- Division of Longevity and Biofunctional Medicine, Pusan National University School of Korean Medicine, 49 Busandaehak-ro, Yangsan, 626-870, Republic of Korea
| | - Jaewoo Song
- Department of Laboratory Medicine, Yonsei University College of Medicine, 50 Yonsei-ro, Seoul, 120-752, Republic of Korea
| | - Sung Joon Kim
- Department of Physiology, Seoul National University College of Medicine, 28 Yongon-dong, Chongro-gu, Seoul, 110-799, Republic of Korea
| | - Joo Hyun Nam
- Department of Physiology, Dongguk University College of Medicine, 123 Dongdae-ro, Kyungju, 780-714, Republic of Korea.
- Channelopathy Research Center (CRC), Dongguk University College of Medicine, 27 Dongguk-ro, Ilsan Dong-gu, Goyang, 410-773, Republic of Korea.
| | - Min Goo Lee
- Department of Pharmacology, BK21 PLUS Project for Medical Sciences, Yonsei University College of Medicine, 50 Yonsei-ro, Seodaemun-gu, Seoul, 120-752, Republic of Korea
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78
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Abstract
Submucosal glands contribute to airway surface liquid (ASL), a film that protects all airway surfaces. Glandular mucus comprises electrolytes, water, the gel-forming mucin MUC5B, and hundreds of different proteins with diverse protective functions. Gland volume per unit area of mucosal surface correlates positively with impaction rate of inhaled particles. In human main bronchi, the volume of the glands is ∼ 50 times that of surface goblet cells, but the glands diminish in size and frequency distally. ASL and its trapped particles are removed from the airways by mucociliary transport. Airway glands have a tubuloacinar structure, with a single terminal duct, a nonciliated collecting duct, then branching secretory tubules lined with mucous cells and ending in serous acini. They allow for a massive increase in numbers of mucus-producing cells without replacing surface ciliated cells. Active secretion of Cl(-) and HCO3 (-) by serous cells produces most of the fluid of gland secretions. Glands are densely innervated by tonically active, mutually excitatory airway intrinsic neurons. Most gland mucus is secreted constitutively in vivo, with large, transient increases produced by emergency reflex drive from the vagus. Elevations of [cAMP]i and [Ca(2+)]i coordinate electrolyte and macromolecular secretion and probably occur together for baseline activity in vivo, with cholinergic elevation of [Ca(2+)]i being mainly responsive for transient increases in secretion. Altered submucosal gland function contributes to the pathology of all obstructive diseases, but is an early stage of pathogenesis only in cystic fibrosis.
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Affiliation(s)
- Jonathan H Widdicombe
- Department of Physiology and Membrane Biology, University of California-Davis, Davis, California; and Department of Psychology and Cystic Fibrosis Research Laboratory, Stanford University, Stanford, California
| | - Jeffrey J Wine
- Department of Physiology and Membrane Biology, University of California-Davis, Davis, California; and Department of Psychology and Cystic Fibrosis Research Laboratory, Stanford University, Stanford, California
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79
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Yu Y, Chen TY. Purified human brain calmodulin does not alter the bicarbonate permeability of the ANO1/TMEM16A channel. ACTA ACUST UNITED AC 2015; 145:79-81. [PMID: 25548138 PMCID: PMC4278188 DOI: 10.1085/jgp.201411294] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Yawei Yu
- Center for Neuroscience and Department of Neurology, University of California, Davis, Davis, CA 95618 Center for Neuroscience and Department of Neurology, University of California, Davis, Davis, CA 95618
| | - Tsung-Yu Chen
- Center for Neuroscience and Department of Neurology, University of California, Davis, Davis, CA 95618 Center for Neuroscience and Department of Neurology, University of California, Davis, Davis, CA 95618
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80
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Jung J, Lee MG. Does calmodulin regulate the bicarbonate permeability of ANO1/TMEM16A or not? ACTA ACUST UNITED AC 2015; 145:75-7. [PMID: 25548137 PMCID: PMC4278186 DOI: 10.1085/jgp.201411283] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Jinsei Jung
- Department of Pharmacology and Brain Korea 21 Plus Project for Medical Sciences, Yonsei University College of Medicine, Seoul 120-752, Korea Department of Pharmacology and Brain Korea 21 Plus Project for Medical Sciences, Yonsei University College of Medicine, Seoul 120-752, Korea
| | - Min Goo Lee
- Department of Pharmacology and Brain Korea 21 Plus Project for Medical Sciences, Yonsei University College of Medicine, Seoul 120-752, Korea Department of Pharmacology and Brain Korea 21 Plus Project for Medical Sciences, Yonsei University College of Medicine, Seoul 120-752, Korea
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81
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Yu Y, Kuan AS, Chen TY. Calcium-calmodulin does not alter the anion permeability of the mouse TMEM16A calcium-activated chloride channel. ACTA ACUST UNITED AC 2015; 144:115-24. [PMID: 24981232 PMCID: PMC4076522 DOI: 10.1085/jgp.201411179] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Ca2+-calmodulin fails to affect TMEM16A anion permeability. The transmembrane protein TMEM16A forms a Ca2+-activated Cl− channel that is permeable to many anions, including SCN−, I−, Br−, Cl−, and HCO3−, and has been implicated in various physiological functions. Indeed, controlling anion permeation through the TMEM16A channel pore may be critical in regulating the pH of exocrine fluids such as the pancreatic juice. The anion permeability of the TMEM16A channel pore has recently been reported to be modulated by Ca2+-calmodulin (CaCaM), such that the pore of the CaCaM-bound channel shows a reduced ability to discriminate between anions as measured by a shift of the reversal potential under bi-ionic conditions. Here, using a mouse TMEM16A clone that contains the two previously identified putative CaM-binding motifs, we were unable to demonstrate such CaCaM-dependent changes in the bi-ionic potential. We confirmed the activity of CaCaM used in our study by showing CaCaM modulation of the olfactory cyclic nucleotide–gated channel. We suspect that the different bi-ionic potentials that were obtained previously from whole-cell recordings in low and high intracellular [Ca2+] may result from different degrees of bi-ionic potential shift secondary to a series resistance problem, an ion accumulation effect, or both.
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Affiliation(s)
- Yawei Yu
- Center for Neuroscience and Department of Neurology, University of California, Davis, Davis, CA 95618
| | - Ai-Seon Kuan
- Center for Neuroscience and Department of Neurology, University of California, Davis, Davis, CA 95618
| | - Tsung-Yu Chen
- Center for Neuroscience and Department of Neurology, University of California, Davis, Davis, CA 95618
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82
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Pang CL, Yuan HB, Cao TG, Su JG, Chen YF, Liu H, Yu H, Zhang HL, Zhan Y, An HL, Han YB. Molecular simulation assisted identification of Ca(2+) binding residues in TMEM16A. J Comput Aided Mol Des 2015; 29:1035-43. [PMID: 26481648 DOI: 10.1007/s10822-015-9876-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 10/12/2015] [Indexed: 01/31/2023]
Abstract
Calcium-activated chloride channels (CaCCs) play vital roles in a variety of physiological processes. Transmembrane protein 16A (TMEM16A) has been confirmed as the molecular counterpart of CaCCs which greatly pushes the molecular insights of CaCCs forward. However, the detailed mechanism of Ca(2+) binding and activating the channel is still obscure. Here, we utilized a combination of computational and electrophysiological approaches to discern the molecular mechanism by which Ca(2+) regulates the gating of TMEM16A channels. The simulation results show that the first intracellular loop serves as a Ca(2+) binding site including D439, E444 and E447. The experimental results indicate that a novel residue, E447, plays key role in Ca(2+) binding. Compared with WT TMEM16A, E447Y produces a 30-fold increase in EC50 of Ca(2+) activation and leads to a 100-fold increase in Ca(2+) concentrations that is needed to fully activate the channel. The following steered molecular dynamic (SMD) simulation data suggests that the mutations at 447 reduce the Ca(2+) dissociation energy. Our results indicated that both the electrical property and the size of the side-chain at residue 447 have significant effects on Ca(2+) dependent gating of TMEM16A.
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Affiliation(s)
- Chun-Li Pang
- Key laboratory of Molecular Biophysics, Tianjin, Hebei Province, China
- Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China
| | - Hong-Bo Yuan
- Key laboratory of Molecular Biophysics, Tianjin, Hebei Province, China
- Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China
| | - Tian-Guang Cao
- Key laboratory of Molecular Biophysics, Tianjin, Hebei Province, China
- Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China
| | - Ji-Guo Su
- School of Sciences, Yanshan University, Qinhuangdao, China
| | - Ya-Fei Chen
- Key laboratory of Molecular Biophysics, Tianjin, Hebei Province, China
- Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China
| | - Hui Liu
- Key laboratory of Molecular Biophysics, Tianjin, Hebei Province, China
- Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China
| | - Hui Yu
- Key laboratory of Molecular Biophysics, Tianjin, Hebei Province, China
- Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China
| | - Hai-Ling Zhang
- Key Laboratory of Neural and Vascular Biology, Ministry of Education, Shijiazhuang, China
- The Key Laboratory of Pharmacology and Toxicology for New Drug, Shijiazhuang, Hebei Province, China
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, China
| | - Yong Zhan
- Key laboratory of Molecular Biophysics, Tianjin, Hebei Province, China.
- Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China.
| | - Hai-Long An
- Key laboratory of Molecular Biophysics, Tianjin, Hebei Province, China.
- Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China.
| | - Yue-Bin Han
- Key laboratory of Molecular Biophysics, Tianjin, Hebei Province, China
- Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China
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83
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Sun Y, Birnbaumer L, Singh BB. TRPC1 regulates calcium-activated chloride channels in salivary gland cells. J Cell Physiol 2015; 230:2848-56. [PMID: 25899321 PMCID: PMC4872598 DOI: 10.1002/jcp.25017] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Accepted: 04/14/2015] [Indexed: 12/19/2022]
Abstract
Calcium-activated chloride channel (CaCC) plays an important role in modulating epithelial secretion. It has been suggested that in salivary tissues, sustained fluid secretion is dependent on Ca(2+) influx that activates ion channels such as CaCC to initiate Cl(-) efflux. However direct evidence as well as the molecular identity of the Ca(2+) channel responsible for activating CaCC in salivary tissues is not yet identified. Here we provide evidence that in human salivary cells, an outward rectifying Cl(-) current was activated by increasing [Ca(2+)]i, which was inhibited by the addition of pharmacological agents niflumic acid (NFA), an antagonist of CaCC, or T16Ainh-A01, a specific TMEM16a inhibitor. Addition of thapsigargin (Tg), that induces store-depletion and activates TRPC1-mediated Ca(2+) entry, potentiated the Cl(-) current, which was inhibited by the addition of a non-specific TRPC channel blocker SKF96365 or removal of external Ca(2+). Stimulation with Tg also increased plasma membrane expression of TMEM16a protein, which was also dependent on Ca(2+) entry. Importantly, in salivary cells, TRPC1 silencing, but not that of TRPC3, inhibited CaCC especially upon store depletion. Moreover, primary acinar cells isolated from submandibular gland also showed outward rectifying Cl(-) currents upon increasing [Ca(2+)]i. These Cl(-) currents were again potentiated with the addition of Tg, but inhibited in the presence of T16Ainh-A01. Finally, acinar cells isolated from the submandibular glands of TRPC1 knockout mice showed significant inhibition of the outward Cl(-) currents without decreasing TMEM16a expression. Together the data suggests that Ca(2+) entry via the TRPC1 channels is essential for the activation of CaCC.
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Affiliation(s)
- Yuyang Sun
- Department of Basic Sciences, School of Medicine Health Sciences, University of North Dakota, Grand Forks, North Dakota
| | - Lutz Birnbaumer
- Laboratory of Signal Transduction, NIHES, NIH, Research Triangle Park, North Carolina
| | - Brij B Singh
- Department of Basic Sciences, School of Medicine Health Sciences, University of North Dakota, Grand Forks, North Dakota
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84
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Physical basis of apparent pore dilation of ATP-activated P2X receptor channels. Nat Neurosci 2015; 18:1577-83. [PMID: 26389841 DOI: 10.1038/nn.4120] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Accepted: 08/25/2015] [Indexed: 12/11/2022]
Abstract
The selectivity of ion channels is fundamental for their roles in electrical and chemical signaling and in ion homeostasis. Although most ion channels exhibit stable ion selectivity, the prevailing view of purinergic P2X receptor channels, transient receptor potential V1 (TRPV1) channels and acid-sensing ion channels (ASICs) is that their ion conduction pores dilate upon prolonged activation. We investigated this mechanism in P2X receptors and found that the hallmark shift in equilibrium potential observed with prolonged channel activation does not result from pore dilation, but from time-dependent alterations in the concentration of intracellular ions. We derived a physical model to calculate ion concentration changes during patch-clamp recordings, which validated our experimental findings and provides a quantitative guideline for effectively controlling ion concentration. Our results have fundamental implications for understanding ion permeation and gating in P2X receptor channels, as well as more broadly for using patch-clamp techniques to study ion channels and neuronal excitability.
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85
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TMEM16, LRRC8A, bestrophin: chloride channels controlled by Ca2+ and cell volume. Trends Biochem Sci 2015; 40:535-43. [DOI: 10.1016/j.tibs.2015.07.005] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Revised: 07/10/2015] [Accepted: 07/10/2015] [Indexed: 01/13/2023]
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86
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Brett TJ. CLCA1 and TMEM16A: the link towards a potential cure for airway diseases. Expert Rev Respir Med 2015; 9:503-6. [PMID: 26296094 DOI: 10.1586/17476348.2015.1081064] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The hallmark traits of chronic obstructive airway diseases are inflammation, airway constriction due to hyperreactivity and mucus overproduction. The current common treatments for asthma and chronic obstructive pulmonary disease target the first two traits with none currently targeting mucus overproduction. The main source of obstructive mucus production is mucus cell metaplasia (MCM), the transdifferentiation of airway epithelial cells into mucus-producing goblet cells, in the small airways. Our current understanding of MCM is profusely incomplete. Few of the molecular players involved in driving MCM in humans have been identified and for many of those that have, their functions and mechanisms are unknown. This fact has limited the development of therapeutics that target mucus overproduction by inhibiting MCM. Current work in the field is aiming to change that.
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Affiliation(s)
- Tom J Brett
- a 1 Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA.,b 2 Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, MO 63110, USA.,c 3 Drug Discovery Program in Pulmonary and Critical Care Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA.,d 4 Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110, USA.,e 5 Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA
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87
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Boedtkjer DMB, Kim S, Jensen AB, Matchkov VM, Andersson KE. New selective inhibitors of calcium-activated chloride channels - T16A(inh) -A01, CaCC(inh) -A01 and MONNA - what do they inhibit? Br J Pharmacol 2015; 172:4158-72. [PMID: 26013995 DOI: 10.1111/bph.13201] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 05/12/2015] [Accepted: 05/15/2015] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND AND PURPOSE T16A(inh)-A01, CaCC(inh)-A01 and MONNA are identified as selective inhibitors of the TMEM16A calcium-activated chloride channel (CaCC). The aim of this study was to examine the chloride-specificity of these compounds on isolated resistance arteries in the presence and absence (±) of extracellular chloride. EXPERIMENTAL APPROACH Isolated resistance arteries were maintained in a myograph and tension recorded, in some instances combined with microelectrode impalement for membrane potential measurements or intracellular calcium monitoring using fura-2. Voltage-dependent calcium currents (VDCC) were measured in A7r5 cells with voltage-clamp electrophysiology using barium as a charge carrier. KEY RESULTS Rodent arteries preconstricted with noradrenaline or U46619 were concentration-dependently relaxed by T16A(inh) -A01 (0.1-10 μM): IC50 and maximum relaxation were equivalent in ±chloride (30 min aspartate substitution) and the T16A(inh) -A01-induced vasorelaxation ±chloride were accompanied by membrane hyperpolarization and lowering of intracellular calcium. However, agonist concentration-response curves ±chloride, with 10 μM T16A(inh) -A01 present, achieved similar maximum constrictions although agonist-sensitivity decreased. Contractions induced by elevated extracellular potassium were concentration-dependently relaxed by T16A(inh)-A01 ±chloride. Moreover, T16A(inh) -A01 inhibited VDCCs in A7r5 cells in a concentration-dependent manner. CaCC(inh) -A01 and MONNA (0.1-10 μM) induced vasorelaxation ±chloride and both compounds lowered maximum contractility. MONNA, 10 μM, induced substantial membrane hyperpolarization under resting conditions. CONCLUSIONS AND IMPLICATIONS T16A(inh) -A01, CaCC(inh) -A01 and MONNA concentration-dependently relax rodent resistance arteries, but an equivalent vasorelaxation occurs when the transmembrane chloride gradient is abolished with an impermeant anion. These compounds therefore display poor selectivity for TMEM16A and inhibition of CaCC in vascular tissue in the concentration range that inhibits the isolated conductance.
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Affiliation(s)
- D M B Boedtkjer
- Department of Biomedicine, Aarhus University, Aarhus, Denmark.,Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Skejby, Denmark.,Department of Gynaecology and Obstetrics, Aarhus University Hospital, Skejby, Denmark
| | - S Kim
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - A B Jensen
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - V M Matchkov
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - K E Andersson
- Department of Biomedicine, Aarhus University, Aarhus, Denmark.,Department of Gynaecology and Obstetrics, Aarhus University Hospital, Skejby, Denmark.,Aarhus Institute of Advanced Studies, Aarhus University, Aarhus, Denmark
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88
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Upregulation of TMEM16A Protein in Bronchial Epithelial Cells by Bacterial Pyocyanin. PLoS One 2015; 10:e0131775. [PMID: 26121472 PMCID: PMC4486680 DOI: 10.1371/journal.pone.0131775] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 06/06/2015] [Indexed: 01/22/2023] Open
Abstract
Induction of mucus hypersecretion in the airway epithelium by Th2 cytokines is associated with the expression of TMEM16A, a Ca2+-activated Cl- channel. We asked whether exposure of airway epithelial cells to bacterial components, a condition that mimics the highly infected environment occurring in cystic fibrosis (CF), also results in a similar response. In cultured human bronchial epithelial cells, treatment with pyocyanin or with a P. aeruginosa culture supernatant caused a significant increase in TMEM16A function. The Ca2+-dependent Cl- secretion, triggered by stimulation with UTP, was particularly enhanced by pyocyanin in cells from CF patients. Increased expression of TMEM16A protein and of MUC5AC mucin by bacterial components was demonstrated by immunofluorescence in CF and non-CF cells. We also investigated TMEM16A expression in human bronchi by immunocytochemistry. We found increased TMEM16A staining in the airways of CF patients. The strongest signal was observed in CF submucosal glands. Our results suggest that TMEM16A expression/function is upregulated in CF lung disease, possibly as a response towards the presence of bacteria in the airways.
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89
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Yang T, Colecraft HM. Calmodulin regulation of TMEM16A and 16B Ca(2+)-activated chloride channels. Channels (Austin) 2015; 10:38-44. [PMID: 26083059 DOI: 10.1080/19336950.2015.1058455] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Ca(2+)-activated chloride channels encoded by TMEM16A and 16B are important for regulating epithelial mucus secretion, cardiac and neuronal excitability, smooth muscle contraction, olfactory transduction, and cell proliferation. Whether and how the ubiquitous Ca(2+) sensor calmodulin (CaM) regulates the activity of TMEM16A and 16B channels has been controversial and the subject of an ongoing debate. Recently, using a bioengineering approach termed ChIMP (Channel Inactivation induced by Membrane-tethering of an associated Protein) we argued that Ca(2+)-free CaM (apoCaM) is pre-associated with functioning TMEM16A and 16B channel complexes in live cells. Further, the pre-associated apoCaM mediates Ca(2+)-dependent sensitization of activation (CDSA) and Ca(2+)-dependent inactivation (CDI) of some TMEM16A splice variants. In this review, we discuss these findings in the context of previous and recent results relating to Ca(2+)-dependent regulation of TMEM16A/16B channels and the putative role of CaM. We further discuss potential future directions for these nascent ideas on apoCaM regulation of TMEM16A/16B channels, noting that such future efforts will benefit greatly from the pioneering work of Dr. David T. Yue and colleagues on CaM regulation of voltage-dependent calcium channels.
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Affiliation(s)
- Tingting Yang
- a Department of Physiology and Cellular Biophysics ; Columbia University; College of Physicians and Surgeons ; New York , NY USA
| | - Henry M Colecraft
- a Department of Physiology and Cellular Biophysics ; Columbia University; College of Physicians and Surgeons ; New York , NY USA
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90
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Leblanc N, Forrest AS, Ayon RJ, Wiwchar M, Angermann JE, Pritchard HAT, Singer CA, Valencik ML, Britton F, Greenwood IA. Molecular and functional significance of Ca(2+)-activated Cl(-) channels in pulmonary arterial smooth muscle. Pulm Circ 2015; 5:244-68. [PMID: 26064450 DOI: 10.1086/680189] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 07/22/2014] [Indexed: 12/31/2022] Open
Abstract
Increased peripheral resistance of small distal pulmonary arteries is a hallmark signature of pulmonary hypertension (PH) and is believed to be the consequence of enhanced vasoconstriction to agonists, thickening of the arterial wall due to remodeling, and increased thrombosis. The elevation in arterial tone in PH is attributable, at least in part, to smooth muscle cells of PH patients being more depolarized and displaying higher intracellular Ca(2+) levels than cells from normal subjects. It is now clear that downregulation of voltage-dependent K(+) channels (e.g., Kv1.5) and increased expression and activity of voltage-dependent (Cav1.2) and voltage-independent (e.g., canonical and vanilloid transient receptor potential [TRPC and TRPV]) Ca(2+) channels play an important role in the functional remodeling of pulmonary arteries in PH. This review focuses on an anion-permeable channel that is now considered a novel excitatory mechanism in the systemic and pulmonary circulations. It is permeable to Cl(-) and is activated by a rise in intracellular Ca(2+) concentration (Ca(2+)-activated Cl(-) channel, or CaCC). The first section outlines the biophysical and pharmacological properties of the channel and ends with a description of the molecular candidate genes postulated to encode for CaCCs, with particular emphasis on the bestrophin and the newly discovered TMEM16 and anoctamin families of genes. The second section provides a review of the various sources of Ca(2+) activating CaCCs, which include stimulation by mobilization from intracellular Ca(2+) stores and Ca(2+) entry through voltage-dependent and voltage-independent Ca(2+) channels. The third and final section summarizes recent findings that suggest a potentially important role for CaCCs and the gene TMEM16A in PH.
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Affiliation(s)
- Normand Leblanc
- Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada, USA
| | - Abigail S Forrest
- Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada, USA
| | - Ramon J Ayon
- Department of Medicine, University of Illinois, Chicago, Illinois, USA
| | - Michael Wiwchar
- Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada, USA
| | - Jeff E Angermann
- School of Community Health Sciences, University of Nevada, Reno, Nevada, USA
| | - Harry A T Pritchard
- Vascular Biology Research Centre, Institute of Cardiovascular and Cell Sciences, St. George's University of London, London, United Kingdom
| | - Cherie A Singer
- Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada, USA
| | - Maria L Valencik
- Department of Biochemistry and Molecular Biology, University of Nevada School of Medicine, Reno, Nevada, USA
| | - Fiona Britton
- Department of Physiology, School of Medical Sciences, University of New South Wales, Sydney, Australia
| | - Iain A Greenwood
- Vascular Biology Research Centre, Institute of Cardiovascular and Cell Sciences, St. George's University of London, London, United Kingdom
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91
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Pritchard HAT, Leblanc N, Albert AP, Greenwood IA. Inhibitory role of phosphatidylinositol 4,5-bisphosphate on TMEM16A-encoded calcium-activated chloride channels in rat pulmonary artery. Br J Pharmacol 2015; 171:4311-21. [PMID: 24834965 DOI: 10.1111/bph.12778] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Revised: 04/22/2014] [Accepted: 05/07/2014] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND AND PURPOSE Calcium-activated chloride channels (CaCCs) are key depolarizing mechanisms that have an important role in vascular smooth muscle contraction. Here, we investigated whether these channels are regulated by phosphatidylinositol (4,5) bisphosphate [P(4,5)P2 ], a known regulator of various ion channels. EXPERIMENTAL APPROACH Calcium-activated Cl(-) currents (IClCa ) were recorded by patch clamp electrophysiology of rat isolated pulmonary artery smooth muscle cells. TMEM16A protein-phosphoinositide interaction was studied by co-immunoprecipitation and phosphoinositide binding arrays on protein lysates from whole pulmonary arteries and HEK293 cells overexpressing TMEM16A, the molecular correlate. KEY RESULTS PI(4,5)P2 and other phospholipids were shown to bind directly to TMEM16A isolated from whole pulmonary artery (PA) and TMEM16A-eGFP expressed in HEK293 cells. Agents that reduced PI(4,5)P2 levels through different routes [PLC activation, PI4K inhibition, PI(4,5)P2 scavenging and absorption] all increased IClCa evoked by solutions containing clamped-free [Ca(2+) ], whereas enrichment of activating solutions with PI(4,5)P2 inhibited IClca in PA smooth muscle cells with approximately 50% reduction at 1 μM. CONCLUSIONS AND IMPLICATIONS These data are the first to show a negative regulation of TMEM16A-encoded CaCCs by PI(4,5)P2 and propose that control of PI(4,5)P2 levels is a key determinant of arterial physiology.
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Affiliation(s)
- H A T Pritchard
- Vascular Biology Research Centre, Institute of Cardiovascular and Cell Sciences, St George's, University of London, London, UK
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92
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Wu H, Guan S, Sun M, Yu Z, Zhao L, He M, Zhao H, Yao W, Wang E, Jin F, Xiao Q, Wei M. Ano1/TMEM16A Overexpression Is Associated with Good Prognosis in PR-Positive or HER2-Negative Breast Cancer Patients following Tamoxifen Treatment. PLoS One 2015; 10:e0126128. [PMID: 25961581 PMCID: PMC4427473 DOI: 10.1371/journal.pone.0126128] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2014] [Accepted: 03/29/2015] [Indexed: 12/31/2022] Open
Abstract
The calcium-activated chloride channel Ano1 (TMEM16A) is overexpressed in many tumors. Although Ano1 overexpression is found in breast cancer due to 11q13 amplification, it remains unclear whether signaling pathways are involved in Ano1 overexpression during breast cancer tumorigenesis in vivo. Estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) have been known to contribute to breast cancer progression. It is unclear whether Ano1 is associated with clinical outcomes in breast cancer patients with different ER, PR and HER2 status. In the present study, we investigated the Ano1 expression in 431 patients with invasive ductal breast carcinoma and 46 patients with fibroadenoma, using immunohistochemistry, and analyzed the association between Ano1 expression and clinical characteristics and outcomes of breast cancer patients with different ER, PR, and HER2 status. Ano1 was overexpressed in breast cancer compared with fibroadenoma. Ano1 was significantly more associated with breast cancer with the lower clinical stage (stage I or II), or triple-negative status. Mostly importantly, Ano1 overexpression was associated with good prognosis in patients with the PR-positive or HER2-negative status, and in patients following tamoxifen treatment. Multivariate Cox regression analysis showed that Ano1 overexpression was a prognostic factor for longer overall survival in PR-positive or HER2-negative patients, and a predictive factor for longer overall survival in patients following tamoxifen treatment. Our findings suggest that Ano1 may be a potential marker for good prognosis in PR-positive or HER2-negative patients following tamoxifen treatment. The PR and HER2 status defines a subtype of breast cancer in which Ano1 overexpression is associated with good prognosis following tamoxifen treatment.
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Affiliation(s)
- Huizhe Wu
- Department of Pharmacology, School of Pharmacy, China Medical University, Shenyang, Liaoning, P. R. China
| | - Shu Guan
- Department of Breast Surgery, First Hospital of China Medical University, Shenyang, Liaoning, P. R. China
| | - Mingli Sun
- Department of Pharmacology, School of Pharmacy, China Medical University, Shenyang, Liaoning, P. R. China
| | - Zhaojin Yu
- Department of Pharmacology, School of Pharmacy, China Medical University, Shenyang, Liaoning, P. R. China
| | - Lin Zhao
- Department of Pharmacology, School of Pharmacy, China Medical University, Shenyang, Liaoning, P. R. China
| | - Miao He
- Department of Pharmacology, School of Pharmacy, China Medical University, Shenyang, Liaoning, P. R. China
| | - Haishan Zhao
- Department of Pharmacology, School of Pharmacy, China Medical University, Shenyang, Liaoning, P. R. China
| | - Weifan Yao
- Department of Pharmacology, School of Pharmacy, China Medical University, Shenyang, Liaoning, P. R. China
| | - Enhua Wang
- Institute of Pathology and Pathophysiology, First Hospital and College of Basic Medical Sciences of China Medical University, Shenyang, Liaoning, P. R. China
| | - Feng Jin
- Department of Breast Surgery, First Hospital of China Medical University, Shenyang, Liaoning, P. R. China
- * E-mail: (MW); (QX); (FJ)
| | - Qinghuan Xiao
- Department of Ion Channel Pharmacology, School of Pharmacy, China Medical University, Shenyang, Liaoning, P. R. China
- * E-mail: (MW); (QX); (FJ)
| | - Minjie Wei
- Department of Pharmacology, School of Pharmacy, China Medical University, Shenyang, Liaoning, P. R. China
- * E-mail: (MW); (QX); (FJ)
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93
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Han JH, Kim HM, Seo DG, Lee G, Jeung EB, Yu FH. Multiple transcripts of anoctamin genes expressed in the mouse submandibular salivary gland. J Periodontal Implant Sci 2015; 45:69-75. [PMID: 25932341 PMCID: PMC4415004 DOI: 10.5051/jpis.2015.45.2.69] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Accepted: 04/20/2015] [Indexed: 12/13/2022] Open
Affiliation(s)
- Ji-Hye Han
- Program in Neurobiology, Seoul National University School of Dentistry and Dental Research Institute, Seoul, Korea
| | - Hye-Mi Kim
- Program in Neurobiology, Seoul National University School of Dentistry and Dental Research Institute, Seoul, Korea
| | - Deog-Gyu Seo
- Department of Conservative Dentistry, Seoul National University School of Dentistry, Seoul, Korea
| | - Gene Lee
- Department of Oral Biochemistry, Seoul National University School of Dentistry, Seoul, Korea
| | - Eui-Bae Jeung
- Laboratory of Veterinary Biochemistry and Molecular Biology, Chungbuk National University College of Veterinary Medicine, Cheongju, Korea
| | - Frank H Yu
- Program in Neurobiology, Seoul National University School of Dentistry and Dental Research Institute, Seoul, Korea
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94
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Bell SC, De Boeck K, Amaral MD. New pharmacological approaches for cystic fibrosis: Promises, progress, pitfalls. Pharmacol Ther 2015; 145:19-34. [DOI: 10.1016/j.pharmthera.2014.06.005] [Citation(s) in RCA: 118] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 06/05/2014] [Indexed: 12/17/2022]
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95
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Jin X, Shah S, Du X, Zhang H, Gamper N. Activation of Ca(2+) -activated Cl(-) channel ANO1 by localized Ca(2+) signals. J Physiol 2014; 594:19-30. [PMID: 25398532 PMCID: PMC4704509 DOI: 10.1113/jphysiol.2014.275107] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 11/08/2014] [Indexed: 12/13/2022] Open
Abstract
Ca2+‐activated chloride channels (CaCCs) regulate numerous physiological processes including epithelial transport, smooth muscle contraction and sensory processing. Anoctamin‐1 (ANO1, TMEM16A) is a principal CaCC subunit in many cell types, yet our understanding of the mechanisms of ANO1 activation and regulation are only beginning to emerge. Ca2+ sensitivity of ANO1 is rather low and at negative membrane potentials the channel requires several micromoles of intracellular Ca2+ for activation. However, global Ca2+ levels in cells rarely reach such levels and, therefore, there must be mechanisms that focus intracellular Ca2+ transients towards the ANO1 channels. Recent findings indeed indicate that ANO1 channels often co‐localize with sources of intracellular Ca2+ signals. Interestingly, it appears that in many cell types ANO1 is particularly tightly coupled to the Ca2+ release sites of the intracellular Ca2+ stores. Such preferential coupling may represent a general mechanism of ANO1 activation in native tissues.
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Affiliation(s)
- Xin Jin
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Sihab Shah
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Xiaona Du
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, China
| | - Hailin Zhang
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, China
| | - Nikita Gamper
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK.,Department of Pharmacology, Hebei Medical University, Shijiazhuang, China
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96
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Preassociated apocalmodulin mediates Ca2+-dependent sensitization of activation and inactivation of TMEM16A/16B Ca2+-gated Cl- channels. Proc Natl Acad Sci U S A 2014; 111:18213-8. [PMID: 25489088 DOI: 10.1073/pnas.1420984111] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Ca(2+)-activated chloride currents carried via transmembrane proteins TMEM16A and TMEM16B regulate diverse processes including mucus secretion, neuronal excitability, smooth muscle contraction, olfactory signal transduction, and cell proliferation. Understanding how TMEM16A/16B are regulated by Ca(2+) is critical for defining their (patho)/physiological roles and for rationally targeting them therapeutically. Here, using a bioengineering approach--channel inactivation induced by membrane-tethering of an associated protein (ChIMP)--we discovered that Ca(2+)-free calmodulin (apoCaM) is preassociated with TMEM16A/16B channel complexes. The resident apoCaM mediates two distinct Ca(2+)-dependent effects on TMEM16A, as revealed by expression of dominant-negative CaM1234. These effects are Ca(2+)-dependent sensitization of activation (CDSA) and Ca(2+)-dependent inactivation (CDI). CDI and CDSA are independently mediated by the N and C lobes of CaM, respectively. TMEM16A alternative splicing provides a mechanism for tuning apoCaM effects. Channels lacking splice segment b selectively lost CDI, and segment a is necessary for apoCaM preassociation with TMEM16A. The results reveal multidimensional regulation of TMEM16A/16B by preassociated apoCaM and introduce ChIMP as a versatile tool to probe the macromolecular complex and function of Ca(2+)-activated chloride channels.
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97
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Bill A, Popa MO, van Diepen MT, Gutierrez A, Lilley S, Velkova M, Acheson K, Choudhury H, Renaud NA, Auld DS, Gosling M, Groot-Kormelink PJ, Gaither LA. Variomics screen identifies the re-entrant loop of the calcium-activated chloride channel ANO1 that facilitates channel activation. J Biol Chem 2014; 290:889-903. [PMID: 25425649 DOI: 10.1074/jbc.m114.618140] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The calcium-activated chloride channel ANO1 regulates multiple physiological processes. However, little is known about the mechanism of channel gating and regulation of ANO1 activity. Using a high-throughput, random mutagenesis-based variomics screen, we generated and functionally characterized ∼6000 ANO1 mutants and identified novel mutations that affected channel activity, intracellular trafficking, or localization of ANO1. Mutations such as S741T increased ANO1 calcium sensitivity and rendered ANO1 calcium gating voltage-independent, demonstrating a critical role of the re-entrant loop in coupling calcium and voltage sensitivity of ANO1 and hence in regulating ANO1 activation. Our data present the first unbiased and comprehensive study of the structure-function relationship of ANO1. The novel ANO1 mutants reported have diverse functional characteristics, providing new tools to study ANO1 function in biological systems, paving the path for a better understanding of the function of ANO1 and its role in health and diseases.
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Affiliation(s)
- Anke Bill
- From the Novartis Institutes for Biomedical Research, Cambridge, Massachusetts 02139
| | - M Oana Popa
- the Novartis Institutes for Biomedical Research, Horsham, West Sussex RH12 5AB, United Kingdom, and
| | - Michiel T van Diepen
- the Novartis Institutes for Biomedical Research, Horsham, West Sussex RH12 5AB, United Kingdom, and
| | - Abraham Gutierrez
- From the Novartis Institutes for Biomedical Research, Cambridge, Massachusetts 02139
| | - Sarah Lilley
- the Novartis Institutes for Biomedical Research, Horsham, West Sussex RH12 5AB, United Kingdom, and
| | - Maria Velkova
- the Novartis Institutes for Biomedical Research, Horsham, West Sussex RH12 5AB, United Kingdom, and
| | - Kathryn Acheson
- the Novartis Institutes for Biomedical Research, Horsham, West Sussex RH12 5AB, United Kingdom, and
| | - Hedaythul Choudhury
- the Novartis Institutes for Biomedical Research, Horsham, West Sussex RH12 5AB, United Kingdom, and
| | - Nicole A Renaud
- From the Novartis Institutes for Biomedical Research, Cambridge, Massachusetts 02139
| | - Douglas S Auld
- From the Novartis Institutes for Biomedical Research, Cambridge, Massachusetts 02139
| | - Martin Gosling
- the Novartis Institutes for Biomedical Research, Horsham, West Sussex RH12 5AB, United Kingdom, and
| | | | - L Alex Gaither
- From the Novartis Institutes for Biomedical Research, Cambridge, Massachusetts 02139,
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98
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Betto G, Cherian OL, Pifferi S, Cenedese V, Boccaccio A, Menini A. Interactions between permeation and gating in the TMEM16B/anoctamin2 calcium-activated chloride channel. ACTA ACUST UNITED AC 2014; 143:703-18. [PMID: 24863931 PMCID: PMC4035747 DOI: 10.1085/jgp.201411182] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Extracellular anions more permeant than Cl− modulate TMEM16B gating to promote channel opening, whereas less permeant anions favor channel closure. At least two members of the TMEM16/anoctamin family, TMEM16A (also known as anoctamin1) and TMEM16B (also known as anoctamin2), encode Ca2+-activated Cl− channels (CaCCs), which are found in various cell types and mediate numerous physiological functions. Here, we used whole-cell and excised inside-out patch-clamp to investigate the relationship between anion permeation and gating, two processes typically viewed as independent, in TMEM16B expressed in HEK 293T cells. The permeability ratio sequence determined by substituting Cl− with other anions (PX/PCl) was SCN− > I− > NO3− > Br− > Cl− > F− > gluconate. When external Cl− was substituted with other anions, TMEM16B activation and deactivation kinetics at 0.5 µM Ca2+ were modified according to the sequence of permeability ratios, with anions more permeant than Cl− slowing both activation and deactivation and anions less permeant than Cl− accelerating them. Moreover, replacement of external Cl− with gluconate, or sucrose, shifted the voltage dependence of steady-state activation (G-V relation) to more positive potentials, whereas substitution of extracellular or intracellular Cl− with SCN− shifted G-V to more negative potentials. Dose–response relationships for Ca2+ in the presence of different extracellular anions indicated that the apparent affinity for Ca2+ at +100 mV increased with increasing permeability ratio. The apparent affinity for Ca2+ in the presence of intracellular SCN− also increased compared with that in Cl−. Our results provide the first evidence that TMEM16B gating is modulated by permeant anions and provide the basis for future studies aimed at identifying the molecular determinants of TMEM16B ion selectivity and gating.
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Affiliation(s)
- Giulia Betto
- Neurobiology Group, International School for Advanced Studies (SISSA), 34136 Trieste, Italy
| | - O Lijo Cherian
- Neurobiology Group, International School for Advanced Studies (SISSA), 34136 Trieste, Italy
| | - Simone Pifferi
- Neurobiology Group, International School for Advanced Studies (SISSA), 34136 Trieste, Italy
| | - Valentina Cenedese
- Neurobiology Group, International School for Advanced Studies (SISSA), 34136 Trieste, Italy
| | - Anna Boccaccio
- Istituto di Biofisica, Consiglio Nazionale delle Ricerche, 16149 Genova, Italy
| | - Anna Menini
- Neurobiology Group, International School for Advanced Studies (SISSA), 34136 Trieste, Italy
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99
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Brunner JD, Lim NK, Schenck S, Duerst A, Dutzler R. X-ray structure of a calcium-activated TMEM16 lipid scramblase. Nature 2014; 516:207-12. [DOI: 10.1038/nature13984] [Citation(s) in RCA: 339] [Impact Index Per Article: 33.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Accepted: 10/20/2014] [Indexed: 12/11/2022]
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100
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TMEM16 proteins: unknown structure and confusing functions. J Mol Biol 2014; 427:94-105. [PMID: 25451786 DOI: 10.1016/j.jmb.2014.09.028] [Citation(s) in RCA: 106] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Revised: 09/24/2014] [Accepted: 09/29/2014] [Indexed: 11/23/2022]
Abstract
The TMEM16 family of membrane proteins, also known as anoctamins, plays key roles in a variety of physiological functions that range from ion transport to phospholipid scrambling and to regulating other ion channels. The first two family members to be functionally characterized, TMEM16A (ANO1) and TMEM16B (ANO2), form Ca(2+)-activated Cl(-) channels and are important for transepithelial ion transport, olfaction, phototransduction, smooth muscle contraction, nociception, cell proliferation and control of neuronal excitability. The roles of other family members, such as TMEM16C (ANO3), TMEM16D (ANO4), TMEM16F (ANO6), TMEM16G (ANO7) and TMEM16J (ANO9), remain poorly understood and controversial. These homologues were reported to be phospholipid scramblases, ion channels, to have both functions or to be regulatory subunits of other channels. Mutations in TMEM16F cause Scott syndrome, a bleeding disorder caused by impaired Ca(2+)-dependent externalization of phosphatidylserine in activated platelets, suggesting that this homologue might be a scramblase. However, overexpression of TMEM16F has also been associated with a remarkable number of different ion channel types, raising the possibility that this protein might be involved in both ion and lipid transports. The recent identification of an ancestral TMEM16 homologue with intrinsic channel and scramblase activities supports this hypothesis. Thus, the TMEM16 family might have diverged in two or three different subclasses, channels, scramblases and dual-function channel/scramblases. The structural bases and functional implication of such a functional diversity within a single protein family remain to be elucidated and the links between TMEM16 functions and human physiology and pathologies need to be investigated.
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