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Amaral MD. Novel personalized therapies for cystic fibrosis: treating the basic defect in all patients. J Intern Med 2015; 277:155-166. [PMID: 25266997 DOI: 10.1111/joim.12314] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Cystic fibrosis (CF) is the most common genetic life-shortening condition in Caucasians. Despite being a multi-organ disease, CF is classically diagnosed by symptoms of acute/chronic respiratory disease, with persistent pulmonary infections and mucus plugging of the airways and failure to thrive. These multiple symptoms originate from dysfunction of the CF transmembrane conductance regulator (CFTR) protein, a channel that mediates anion transport across epithelia. Indeed, establishment of a definite CF diagnosis requires proof of CFTR dysfunction, commonly through the so-called sweat Cl(-) test. Many drug therapies, including mucolytics and antibiotics, aim to alleviate the symptoms of CF lung disease. However, new therapies to modulate defective CFTR, the basic defect underlying CF, have started to reach the clinic, and several others are in development or in clinical trials. The novelty of these therapies is that, besides targeting the basic defect underlying CF, they are mutation specific. Indeed, even this monogenic disease is influenced by a large number of different genes and biological pathways as well as by environmental factors that are difficult to assess. Accordingly, every person with CF is unique and so functional assessment of patients' tissues ex vivo is key for diagnosing and predicting the severity of this disease. Of note, such assessment will also be crucial to assess drug responses, in order to effectively treat all CF patients. It is not because it is a monogenic disorder that personalized treatment for CF is much easier than for complex disorders.
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Affiliation(s)
- M D Amaral
- BioFIG-Center for Biodiversity, Functional and Integrative Genomics, Faculty of Sciences, University of Lisboa, Lisboa, Portugal
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52
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Stolz M, Klapperstück M, Kendzierski T, Detro-Dassen S, Panning A, Schmalzing G, Markwardt F. Homodimeric anoctamin-1, but not homodimeric anoctamin-6, is activated by calcium increases mediated by the P2Y1 and P2X7 receptors. Pflugers Arch 2015; 467:2121-40. [PMID: 25592660 DOI: 10.1007/s00424-015-1687-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Revised: 12/23/2014] [Accepted: 01/06/2015] [Indexed: 01/14/2023]
Abstract
The P2X7 receptor (P2X7R) is a ligand-gated ion channel that conducts Na(+), K(+), and Ca(2+) when activated by extracellular ATP. In various cell types, such as secretory epithelia, the P2X7R is co-expressed with Ca(2+)-dependent Cl(-) channels of the TMEM16/anoctamin family. Here, we studied whether the P2X7R and TMEM16A/anoctamin-1 (Ano1) or TMEM16F/anoctamin-6 (Ano6) interact functionally and physically, using oocytes of Xenopus laevis and Ambystoma mexicanum (Axolotl) for heterologous expression. As a control, we co-expressed anoctamin-1 with the P2Y1 receptor (P2Y1R), which induces the release of Ca(2+) from intracellular stores via activating phospholipase C through coupling to Gαq. We found that co-expression of anoctamin-1 with the P2Y1R resulted in a small transient increase in Cl(-) conductance in response to ATP. Co-expression of anoctamin-1 with the P2X7R resulted in a large sustained increase in Cl(-) conductance via Ca(2+) influx through the ATP-opened P2X7R in Xenopus and in Axolotl oocytes, which lack endogenous Ca(2+)-dependent Cl(-) channels. P2Y1R- or P2X7R-mediated stimulation of Ano1 was primarily functional, as demonstrated by the absence of a physically stable interaction between Ano1 and the P2X7R. In the pancreatic cell line AsPC-1, we found the same functional Ca(2+)-dependent interaction of P2X7R and Ano1. The P2X7R-mediated sustained activation of Ano1 may be physiologically relevant to the time course of stimulus-secretion coupling in secretory epithelia. No such increase in Cl(-) conductance could be elicited by activating the P2X7 receptor in either Xenopus oocytes or Axolotl oocytes co-expressing Ano6. The lack of function of Ano6 can, at least in part, be explained by its poor cell-surface expression, resulting from a relatively inefficient exit of the homodimeric Ano6 from the endoplasmic reticulum.
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Affiliation(s)
- Michaela Stolz
- Molecular Pharmacology, RWTH Aachen University, Wendlingweg 2, D-52074, Aachen, Germany
| | - Manuela Klapperstück
- Julius-Bernstein-Institute for Physiology, Martin-Luther-University Halle-Wittenberg, Magdeburger Str. 6, D-06097, Halle/Saale, Germany
| | - Thomas Kendzierski
- Julius-Bernstein-Institute for Physiology, Martin-Luther-University Halle-Wittenberg, Magdeburger Str. 6, D-06097, Halle/Saale, Germany
| | - Silvia Detro-Dassen
- Molecular Pharmacology, RWTH Aachen University, Wendlingweg 2, D-52074, Aachen, Germany
| | - Anna Panning
- Molecular Pharmacology, RWTH Aachen University, Wendlingweg 2, D-52074, Aachen, Germany
| | - Günther Schmalzing
- Molecular Pharmacology, RWTH Aachen University, Wendlingweg 2, D-52074, Aachen, Germany
| | - Fritz Markwardt
- Julius-Bernstein-Institute for Physiology, Martin-Luther-University Halle-Wittenberg, Magdeburger Str. 6, D-06097, Halle/Saale, Germany.
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53
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Intracellular Cl- as a signaling ion that potently regulates Na+/HCO3- transporters. Proc Natl Acad Sci U S A 2015; 112:E329-37. [PMID: 25561556 DOI: 10.1073/pnas.1415673112] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cl(-) is a major anion in mammalian cells involved in transport processes that determines the intracellular activity of many ions and plasma membrane potential. Surprisingly, a role of intracellular Cl(-) (Cl(-) in) as a signaling ion has not been previously evaluated. Here we report that Cl(-) in functions as a regulator of cellular Na(+) and HCO3 (-) concentrations and transepithelial transport through modulating the activity of several electrogenic Na(+)-HCO3 (-) transporters. We describe the molecular mechanism(s) of this regulation by physiological Cl(-) in concentrations highlighting the role of GXXXP motifs in Cl(-) sensing. Regulation of the ubiquitous Na(+)-HCO3(-) co-transport (NBC)e1-B is mediated by two GXXXP-containing sites; regulation of NBCe2-C is dependent on a single GXXXP motif; and regulation of NBCe1-A depends on a cryptic GXXXP motif. In the basal state NBCe1-B is inhibited by high Cl(-) in interacting at a low affinity GXXXP-containing site. IP3 receptor binding protein released with IP3 (IRBIT) activation of NBCe1-B unmasks a second high affinity Cl(-) in interacting GXXXP-dependent site. By contrast, NBCe2-C, which does not interact with IRBIT, has a single high affinity N-terminal GXXP-containing Cl(-) in interacting site. NBCe1-A is unaffected by Cl(-) in between 5 and 140 mM. However, deletion of NBCe1-A residues 29-41 unmasks a cryptic GXXXP-containing site homologous with the NBCe1-B low affinity site that is involved in inhibition of NBCe1-A by Cl(-) in. These findings reveal a cellular Cl(-) in sensing mechanism that plays an important role in the regulation of Na(+) and HCO3 (-) transport, with critical implications for the role of Cl(-) in cellular ion homeostasis and epithelial fluid and electrolyte secretion.
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54
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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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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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56
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Gokhale A, Perez-Cornejo P, Duran C, Hartzell HC, Faundez V. A comprehensive strategy to identify stoichiometric membrane protein interactomes. CELLULAR LOGISTICS 2014; 2:189-196. [PMID: 23676845 PMCID: PMC3607620 DOI: 10.4161/cl.22717] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
There are numerous experimental approaches to identify the interaction networks of soluble proteins, but strategies for the identification of membrane protein interactomes remain limited. We discuss in detail the logic of an experimental design that led us to identify the interactome of a membrane protein of complex membrane topology, the calcium activated chloride channel Anoctamin 1/Tmem16a (Ano1). We used covalent chemical stabilizers of protein-protein interactions combined with magnetic bead immuno-affinity chromatography, quantitative SILAC mass-spectrometry and in silico network construction. This strategy led us to define a putative Ano1 interactome from which we selected key components for functional testing. We propose a combination of procedures to narrow down candidate proteins interacting with a membrane protein of interest for further functional studies.
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Affiliation(s)
- Avanti Gokhale
- Department of Cell Biology; Emory University School of Medicine; Atlanta, GA USA
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57
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Vocke K, Dauner K, Hahn A, Ulbrich A, Broecker J, Keller S, Frings S, Möhrlen F. Calmodulin-dependent activation and inactivation of anoctamin calcium-gated chloride channels. ACTA ACUST UNITED AC 2014; 142:381-404. [PMID: 24081981 PMCID: PMC3787769 DOI: 10.1085/jgp.201311015] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Calcium-dependent chloride channels serve critical functions in diverse biological systems. Driven by cellular calcium signals, the channels codetermine excitatory processes and promote solute transport. The anoctamin (ANO) family of membrane proteins encodes three calcium-activated chloride channels, named ANO 1 (also TMEM16A), ANO 2 (also TMEM16B), and ANO 6 (also TMEM16F). Here we examined how ANO 1 and ANO 2 interact with Ca2+/calmodulin using nonstationary current analysis during channel activation. We identified a putative calmodulin-binding domain in the N-terminal region of the channel proteins that is involved in channel activation. Binding studies with peptides indicated that this domain, a regulatory calmodulin-binding motif (RCBM), provides two distinct modes of interaction with Ca2+/calmodulin, one at submicromolar Ca2+ concentrations and one in the micromolar Ca2+ range. Functional, structural, and pharmacological data support the concept that calmodulin serves as a calcium sensor that is stably associated with the RCBM domain and regulates the activation of ANO 1 and ANO 2 channels. Moreover, the predominant splice variant of ANO 2 in the brain exhibits Ca2+/calmodulin-dependent inactivation, a loss of channel activity within 30 s. This property may curtail ANO 2 activity during persistent Ca2+ signals in neurons. Mutagenesis data indicated that the RCBM domain is also involved in ANO 2 inactivation, and that inactivation is suppressed in the retinal ANO 2 splice variant. These results advance the understanding of Ca2+ regulation in anoctamin Cl− channels and its significance for the physiological function that anoctamin channels subserve in neurons and other cell types.
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Affiliation(s)
- Kerstin Vocke
- Department of Molecular Physiology, Centre for Organismal Studies, Heidelberg University, 69120 Heidelberg, Germany
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58
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Anoctamins support calcium-dependent chloride secretion by facilitating calcium signaling in adult mouse intestine. Pflugers Arch 2014; 467:1203-13. [PMID: 24974903 DOI: 10.1007/s00424-014-1559-2] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Revised: 06/12/2014] [Accepted: 06/17/2014] [Indexed: 12/13/2022]
Abstract
Intestinal epithelial electrolyte secretion is activated by increase in intracellular cAMP or Ca(2+) and opening of apical Cl(-) channels. In infants and young animals, but not in adults, Ca(2+)-activated chloride channels may cause secretory diarrhea during rotavirus infection. While detailed knowledge exists concerning the contribution of cAMP-activated cystic fibrosis transmembrane conductance regulator (CFTR) channels, analysis of the role of Ca(2+)-dependent Cl(-) channels became possible through identification of the anoctamin (TMEM16) family of proteins. We demonstrate expression of several anoctamin paralogues in mouse small and large intestines. Using intestinal-specific mouse knockout models for anoctamin 1 (Ano1) and anoctamin 10 (Ano10) and a conventional knockout model for anoctamin 6 (Ano6), we demonstrate the role of anoctamins for Ca(2+)-dependent Cl(-) secretion induced by the muscarinic agonist carbachol (CCH). Ano1 is preferentially expressed in the ileum and large intestine, where it supports Ca(2+)-activated Cl(-) secretion. In contrast, Ano10 is essential for Ca(2+)-dependent Cl(-) secretion in jejunum, where expression of Ano1 was not detected. Although broadly expressed, Ano6 has no role in intestinal cholinergic Cl(-) secretion. Ano1 is located in a basolateral compartment/membrane rather than in the apical membrane, where it supports CCH-induced Ca(2+) increase, while the essential and possibly only apical Cl(-) channel is CFTR. These results define a new role of Ano1 for intestinal Ca(2+)-dependent Cl(-) secretion and demonstrate for the first time a contribution of Ano10 to intestinal transport.
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59
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Tien J, Peters CJ, Wong XM, Cheng T, Jan YN, Jan LY, Yang H. A comprehensive search for calcium binding sites critical for TMEM16A calcium-activated chloride channel activity. eLife 2014; 3. [PMID: 24980701 PMCID: PMC4112547 DOI: 10.7554/elife.02772] [Citation(s) in RCA: 100] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Accepted: 06/28/2014] [Indexed: 12/19/2022] Open
Abstract
TMEM16A forms calcium-activated chloride channels (CaCCs) that regulate physiological processes such as the secretions of airway epithelia and exocrine glands, the contraction of smooth muscles, and the excitability of neurons. Notwithstanding intense interest in the mechanism behind TMEM16A-CaCC calcium-dependent gating, comprehensive surveys to identify and characterize potential calcium sensors of this channel are still lacking. By aligning distantly related calcium-activated ion channels in the TMEM16 family and conducting systematic mutagenesis of all conserved acidic residues thought to be exposed to the cytoplasm, we identify four acidic amino acids as putative calcium-binding residues. Alterations of the charge, polarity, and size of amino acid side chains at these sites alter the ability of different divalent cations to activate the channel. Furthermore, TMEM16A mutant channels containing double cysteine substitutions at these residues are sensitive to the redox potential of the internal solution, providing evidence for their physical proximity and solvent accessibility. DOI:http://dx.doi.org/10.7554/eLife.02772.001 Every cell in the body is surrounded by a barrier called the cell membrane. There are, however, a number of ways that molecules can pass through this membrane to either enter or leave the cell. Calcium-activated channels are a group of proteins that are embedded within the cell membrane and that allow different ions to pass through the membrane. These proteins are involved in a number of processes in a variety of tissues, for example in the gut, lungs and nervous system. A family of proteins called TMEM16 includes a number of calcium-activated channels that have been recently identified. However, it is not clear how these TMEM16 channel proteins detect the calcium ions that cause them to open. Two ideas have been suggested: the calcium ions might be detected by a protein called calmodulin, which then forces the channel to open; alternatively, the calcium ions might be detected by the channel protein itself. Tien, Peters et al. have now tested both of these ideas by focusing on a calcium-activated channel protein called TMEM16A, which allows chloride ions to pass through membranes. The possible role of calmodulin was tested in several ways, such as by preventing it from binding to the TMEM16A protein or from binding to calcium. However, none of these changes affected the opening of the channel; so Tien, Peters et al. concluded that calmodulin is not involved in these channels being activated by calcium ions. Next, Tien, Peters et al. tested specific parts of the TMEM16A channel protein itself to see if they were involved in calcium detection instead. Proteins are made from smaller building blocks called amino acids, and it is known that some amino acids are more likely to bind to calcium ions than others. There are 38 of these amino acids in the TMEM16A channel that are also found in other members of the TMEM16 family in both fruit flies and mammals. Tien, Peters et al. found that replacing five of these with other amino acids made the channel less sensitive to calcium. Further experiments suggested that four of these five amino acids are clustered at the site where a calcium ion might bind to the TMEM16A channel protein, which suggests that the protein itself can detect calcium directly. The next challenge will be to understand how calcium ions binding to the site on the TMEM16A channel protein can cause the channel to open to allow the chloride ions to pass through. DOI:http://dx.doi.org/10.7554/eLife.02772.002
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Affiliation(s)
- Jason Tien
- Department of Physiology, University of California, San Francisco, San Francisco, United States
| | - Christian J Peters
- Department of Physiology, University of California, San Francisco, San Francisco, United States
| | - Xiu Ming Wong
- Graduate Program in Chemistry and Chemical Biology, University of California, San Francisco, San Francisco, United States
| | - Tong Cheng
- Department of Physiology, University of California, San Francisco, San Francisco, United States
| | - Yuh Nung Jan
- Department of Physiology, University of California, San Francisco, San Francisco, United States
| | - Lily Yeh Jan
- Department of Physiology, University of California, San Francisco, San Francisco, United States
| | - Huanghe Yang
- Department of Physiology, University of California, San Francisco, San Francisco, United States
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60
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Xiao Q, Cui Y. Acidic amino acids in the first intracellular loop contribute to voltage- and calcium- dependent gating of anoctamin1/TMEM16A. PLoS One 2014; 9:e99376. [PMID: 24901998 PMCID: PMC4047086 DOI: 10.1371/journal.pone.0099376] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Accepted: 05/13/2014] [Indexed: 11/18/2022] Open
Abstract
Anoctamin1 (Ano1, or TMEM16A) is a Ca2+-activated chloride channel that is gated by both voltage and Ca2+. We have previously identified that the first intracellular loop that contains a high density of acidic residues mediates voltage- and calcium-dependent gating of Ano1. Mutation of the four consecutive glutamates (444EEEE447) inhibits the voltage-dependent activation of Ano1, whereas deletion of these residues decreases apparent Ca2+ sensitivity. In the present study, we further found that deletion of 444EEEEEAVKD452 produced a more than 40-fold decrease in the apparent Ca2+ sensitivity with altered activation kinetics. We then systematically mutated each acidic residue into alanine, and analyzed the voltage- and calcium dependent activation of each mutation. Activation kinetics of wild type Ano1 consisted of a fast component (τfast) that represented voltage-dependent mode, and a slow component (τslow) that reflected the Ca2+-dependent modal gating. E444A, E445A, E446A, E447A, E448A, and E457A mutations showed a decrease in the τfast, significantly inhibited voltage-dependent activation of Ano1 in the absence of Ca2+, and greatly shifted the G-V curve to the right, suggesting that these glutamates are involved in voltage-gating of Ano1. Furthermore, D452A, E464A, E470A, and E475A mutations that did not alter voltage-dependent activation of the channel, significantly decreased Ca2+ dependence of G-V curve, exhibited an increase in the τslow, and produced a 2-3 fold decrease in the apparent Ca2+ sensitivity, suggesting that these acidic residues are involved in Ca2+-dependent gating of the channel. Our data show that acidic residues in the first intracellular loop are the important structural determinant that couples the voltage and calcium dependent gating of Ano1.
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Affiliation(s)
- Qinghuan Xiao
- From the Department of Ion Channel Pharmacology, School of Pharmacy, China Medical University, Shenyang, China
- * E-mail:
| | - Yuanyuan Cui
- Department of Cell biology, School of Medicine, Emory University, Atlanta, Georgia, United States of America
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61
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Hoffmann EK, Holm NB, Lambert IH. Functions of volume-sensitive and calcium-activated chloride channels. IUBMB Life 2014; 66:257-67. [PMID: 24771413 DOI: 10.1002/iub.1266] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 03/31/2014] [Accepted: 03/31/2014] [Indexed: 01/23/2023]
Abstract
The review describes molecular and functional properties of the volume regulated anion channel and Ca(2+)-dependent Cl(-) channels belonging to the anoctamin family with emphasis on physiological importance of these channels in regulation of cell volume, cell migration, cell proliferation, and programmed cell death. Finally, we discuss the role of Cl(-) channels in various diseases.
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Affiliation(s)
- Else Kay Hoffmann
- Department of Biology, University of Copenhagen, 13 Universitetsparken, Copenhagen Ø, Denmark
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62
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Ruppersburg CC, Hartzell HC. The Ca2+-activated Cl- channel ANO1/TMEM16A regulates primary ciliogenesis. Mol Biol Cell 2014; 25:1793-807. [PMID: 24694595 PMCID: PMC4038505 DOI: 10.1091/mbc.e13-10-0599] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The Ca2+-activated Cl− channel ANO1/TMEM16A is located in the primary cilium, and blocking it pharmacologically or knocking it down with shRNA interferes with ciliogenesis. Before ciliogenesis, the channel is organized into a torus-shaped structure (the “nimbus”) enriched in proteins required for ciliogenesis. Many cells possess a single, nonmotile, primary cilium highly enriched in receptors and sensory transduction machinery that plays crucial roles in cellular morphogenesis. Although sensory transduction requires ion channels, relatively little is known about ion channels in the primary cilium (with the exception of TRPP2). Here we show that the Ca2+-activated Cl− channel anoctamin-1 (ANO1/TMEM16A) is located in the primary cilium and that blocking its channel function pharmacologically or knocking it down with short hairpin RNA interferes with ciliogenesis. Before ciliogenesis, the channel becomes organized into a torus-shaped structure (“the nimbus”) enriched in proteins required for ciliogenesis, including the small GTPases Cdc42 and Arl13b and the exocyst complex component Sec6. The nimbus excludes F-actin and coincides with a ring of acetylated microtubules. The nimbus appears to form before, or independent of, apical docking of the mother centriole. Our data support a model in which the nimbus provides a scaffold for staging of ciliary components for assembly very early in ciliogenesis and chloride transport by ANO1/TMEM16A is required for the genesis or maintenance of primary cilia.
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Affiliation(s)
| | - H Criss Hartzell
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322
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63
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Wanitchakool P, Wolf L, Koehl GE, Sirianant L, Schreiber R, Kulkarni S, Duvvuri U, Kunzelmann K. Role of anoctamins in cancer and apoptosis. Philos Trans R Soc Lond B Biol Sci 2014; 369:20130096. [PMID: 24493744 PMCID: PMC3917350 DOI: 10.1098/rstb.2013.0096] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Anoctamin 1 (TMEM16A, Ano1) is a recently identified Ca(2+)-activated chloride channel and a member of a large protein family comprising 10 paralogues. Before Ano1 was identified as a chloride channel protein, it was known as the cancer marker DOG1. DOG1/Ano1 is expressed in gastrointestinal stromal tumours (GIST) and particularly in head and neck squamous cell carcinoma, at very high levels never detected in other tissues. It is now emerging that Ano1 is part of the 11q13 locus, amplified in several types of tumour, where it is thought to augment cell proliferation, cell migration and metastasis. Notably, Ano1 is upregulated through histone deacetylase (HDAC), corresponding to the known role of HDAC in HNSCC. As Ano1 does not enhance proliferation in every cell type, its function is perhaps modulated by cell-specific factors, or by the abundance of other anoctamins. Thus Ano6, by regulating Ca(2+)-induced membrane phospholipid scrambling and annexin V binding, supports cellular apoptosis rather than proliferation. Current findings implicate other cellular functions of anoctamins, apart from their role as Ca(2+)-activated Cl(-) channels.
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Affiliation(s)
- Podchanart Wanitchakool
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, Regensburg 93053, Germany
| | - Luisa Wolf
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, Regensburg 93053, Germany
| | - Gudrun E. Koehl
- Department of Surgery, University Medical Center Regensburg, University of Regensburg, Regensburg, Germany
| | - Lalida Sirianant
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, Regensburg 93053, Germany
| | - Rainer Schreiber
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, Regensburg 93053, Germany
| | - Sucheta Kulkarni
- Ear & Eye Institute, University of Pittsburgh Medical Center, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - Umamaheswar Duvvuri
- Ear & Eye Institute, University of Pittsburgh Medical Center, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - Karl Kunzelmann
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, Regensburg 93053, Germany
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64
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Qu Z, Yao W, Yao R, Liu X, Yu K, Hartzell C. The Ca(2+) -activated Cl(-) channel, ANO1 (TMEM16A), is a double-edged sword in cell proliferation and tumorigenesis. Cancer Med 2014; 3:453-61. [PMID: 24639373 PMCID: PMC4101736 DOI: 10.1002/cam4.232] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2013] [Revised: 02/13/2014] [Accepted: 02/21/2014] [Indexed: 01/11/2023] Open
Abstract
Since anoctamin 1 ANO1 (TMEM16A) was found to be a molecular component of Ca2+-activated Cl− channels, its role in tumorigenesis has gained attention at a fast pace. ANO1 overexpression frequently occurs in the cancer tissues along with 11q13 chromosome amplification. Poor prognosis of many types of cancers has been closely correlated with ANO1 gene amplification and protein overexpression. ANO1 is now considered an excellent biomarker for certain cancers. Recent research suggests that it is the channel function of ANO1 that is involved in the tumorigenesis. However, how the overexpression of the functional ANO1 causes malignant transformation of tissues via signaling pathways, for example, MAPK remains to be investigated. Clarification of the reasons in future will avail to make ANO1 as a target for cancer treatment.
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Affiliation(s)
- Zhiqiang Qu
- Medical Research Center, Affiliated Hospital, Qingdao University, Qingdao, 266555, China; State Key Physiological Discipline, Qingdao University, Qingdao, 266555, China
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ANO1 contributes to Angiotensin-II-activated Ca2+-dependent Cl− current in human atrial fibroblasts. J Mol Cell Cardiol 2014; 68:12-9. [DOI: 10.1016/j.yjmcc.2013.12.027] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Revised: 12/03/2013] [Accepted: 12/31/2013] [Indexed: 01/04/2023]
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66
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Kunzelmann K, Nilius B, Owsianik G, Schreiber R, Ousingsawat J, Sirianant L, Wanitchakool P, Bevers EM, Heemskerk JWM. Molecular functions of anoctamin 6 (TMEM16F): a chloride channel, cation channel, or phospholipid scramblase? Pflugers Arch 2014; 466:407-14. [PMID: 23748496 DOI: 10.1007/s00424-013-1305-1] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Revised: 05/27/2013] [Accepted: 05/28/2013] [Indexed: 10/26/2022]
Abstract
Anoctamin 6 (Ano6; TMEM16F gene) is a ubiquitous protein; the expression of which is defective in patients with Scott syndrome, an inherited bleeding disorder based on defective scrambling of plasma membrane phospholipids. For Ano6, quite diverse functions have been described: (1) it can form an outwardly rectifying, Ca(2+)-dependent and a volume-regulated Cl(-) channel; (2) it was claimed to be a Ca(2+)-regulated nonselective cation channel permeable for Ca(2+); (3) it was shown to be essential for Ca(2+)-mediated scrambling of membrane phospholipids; and (4) it can regulate cell blebbing and microparticle shedding. Deficiency of Ano6 in blood cells from Scott patients or Ano6 null mice appears to affect all of these cell responses. Furthermore, Ano6 deficiency in mice impairs the mineralization of osteoblasts, resulting in reduced skeletal development. These diverse results have been obtained under different experimental conditions, which may explain some of the contradictions. This review therefore aims to summarize the currently available information on the diverse roles of Ano6 and tries to clear up some of the existing controversies.
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Affiliation(s)
- Karl Kunzelmann
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany,
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67
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Wittkowski KM, Sonakya V, Bigio B, Tonn MK, Shic F, Ascano M, Nasca C, Gold-Von Simson G. A novel computational biostatistics approach implies impaired dephosphorylation of growth factor receptors as associated with severity of autism. Transl Psychiatry 2014; 4:e354. [PMID: 24473445 PMCID: PMC3905234 DOI: 10.1038/tp.2013.124] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Revised: 11/16/2013] [Accepted: 11/25/2013] [Indexed: 01/05/2023] Open
Abstract
The prevalence of autism spectrum disorders (ASDs) has increased 20-fold over the past 50 years to >1% of US children. Although twin studies attest to a high degree of heritability, the genetic risk factors are still poorly understood. We analyzed data from two independent populations using u-statistics for genetically structured wide-locus data and added data from unrelated controls to explore epistasis. To account for systematic, but disease-unrelated differences in (non-randomized) genome-wide association studies (GWAS), a correlation between P-values and minor allele frequency with low granularity data and for conducting multiple tests in overlapping genetic regions, we present a novel study-specific criterion for 'genome-wide significance'. From recent results in a comorbid disease, childhood absence epilepsy, we had hypothesized that axonal guidance and calcium signaling are involved in autism as well. Enrichment of the results in both studies with related genes confirms this hypothesis. Additional ASD-specific variations identified in this study suggest protracted growth factor signaling as causing more severe forms of ASD. Another cluster of related genes suggests chloride and potassium ion channels as additional ASD-specific drug targets. The involvement of growth factors suggests the time of accelerated neuronal growth and pruning at 9-24 months of age as the period during which treatment with ion channel modulators would be most effective in preventing progression to more severe forms of autism. By extension, the same computational biostatistics approach could yield profound insights into the etiology of many common diseases from the genetic data collected over the last decade.
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Affiliation(s)
- K M Wittkowski
- The Rockefeller University, Center for Clinical and Translational Science, New York, NY, USA
| | - V Sonakya
- The Rockefeller University, Center for Clinical and Translational Science, New York, NY, USA
| | - B Bigio
- The Rockefeller University, Center for Clinical and Translational Science, New York, NY, USA
| | - M K Tonn
- Hochschule Koblenz, RheinAhrCampus, Joseph-Rovan-Allee 2, Remagen, Germany
| | - F Shic
- Yale School of Medicine, Yale Autism Program, New Haven, CT, USA
| | - M Ascano
- Tuschl Laboratory of RNA Molecular Biology, The Rockefeller University, New York, NY, USA
| | - C Nasca
- McEwen Laboratory of Neuroendocrinology, The Rockefeller University, New York, NY, USA
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Alexander SPH, Benson HE, Faccenda E, Pawson AJ, Sharman JL, Catterall WA, Spedding M, Peters JA, Harmar AJ. The Concise Guide to PHARMACOLOGY 2013/14: ion channels. Br J Pharmacol 2013; 170:1607-51. [PMID: 24528239 PMCID: PMC3892289 DOI: 10.1111/bph.12447] [Citation(s) in RCA: 224] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The Concise Guide to PHARMACOLOGY 2013/14 provides concise overviews of the key properties of over 2000 human drug targets with their pharmacology, plus links to an open access knowledgebase of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. The full contents can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.12444/full. Ion channels are one of the seven major pharmacological targets into which the Guide is divided, with the others being G protein-coupled receptors, ligand-gated ion channels, catalytic receptors, nuclear hormone receptors, transporters and enzymes. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. A new landscape format has easy to use tables comparing related targets. It is a condensed version of material contemporary to late 2013, which is presented in greater detail and constantly updated on the website www.guidetopharmacology.org, superseding data presented in previous Guides to Receptors and Channels. It is produced in conjunction with NC-IUPHAR and provides the official IUPHAR classification and nomenclature for human drug targets, where appropriate. It consolidates information previously curated and displayed separately in IUPHAR-DB and the Guide to Receptors and Channels, providing a permanent, citable, point-in-time record that will survive database updates.
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Affiliation(s)
- Stephen PH Alexander
- School of Life Sciences, University of Nottingham Medical SchoolNottingham, NG7 2UH, UK
- *
Author for correspondence;
| | - Helen E Benson
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Elena Faccenda
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Adam J Pawson
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Joanna L Sharman
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - William A Catterall
- University of Washington, School of Medicine, Department of PharmacologyBox 357280, Seattle, WA 98195-7280, USA
| | | | - John A Peters
- Neuroscience Division, Medical Education Institute, Ninewells Hospital and Medical School, University of DundeeDundee, DD1 9SY, UK
| | - Anthony J Harmar
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
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70
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Wang Y, Alam T, Hill-Harfe K, Lopez AJ, Leung CK, Iribarne D, Bruggeman B, Miyamoto MM, Harfe BD, Choe KP. Phylogenetic, expression, and functional analyses of anoctamin homologs in Caenorhabditis elegans. Am J Physiol Regul Integr Comp Physiol 2013; 305:R1376-89. [DOI: 10.1152/ajpregu.00303.2012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ca2+-activated Cl− channels (CaCCs) are critical to processes such as epithelial transport, membrane excitability, and signal transduction. Anoctamin, or TMEM16, is a family of 10 mammalian transmembrane proteins, 2 of which were recently shown to function as CaCCs. The functions of other family members have not been firmly established, and almost nothing is known about anoctamins in invertebrates. Therefore, we performed a phylogenetic analysis of anoctamins across the animal kingdom and examined the expression and function of anoctamins in the genetically tractable nematode Caenorhabditis elegans. Phylogenetic analyses support five anoctamin clades that are at least as old as the deuterostome/protosome ancestor. This includes a branch containing two Drosophila paralogs that group with mammalian ANO1 and ANO2, the two best characterized CaCCs. We identify two anoctamins in C. elegans (ANOH-1 and ANOH-2) that are also present in basal metazoans. The anoh-1 promoter is active in amphid sensory neurons that detect external chemical and nociceptive cues. Within amphid neurons, ANOH-1::GFP fusion protein is enriched within sensory cilia. RNA interference silencing of anoh-1 reduced avoidance of steep osmotic gradients without disrupting amphid cilia development, chemotaxis, or withdrawal from noxious stimuli, suggesting that ANOH-1 functions in a sensory mode-specific manner. The anoh-2 promoter is active in mechanoreceptive neurons and the spermatheca, but loss of anoh-2 had no effect on motility or brood size. Our study indicates that at least five anoctamin duplicates are evolutionarily ancient and suggests that sensory signaling may be a basal function of the anoctamin protein family.
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Affiliation(s)
- Ying Wang
- Department of Biology, University of Florida, Gainesville, Florida
| | - Tashrique Alam
- Department of Biology, University of Florida, Gainesville, Florida
| | | | | | - Chi K. Leung
- Department of Biology, University of Florida, Gainesville, Florida
| | - Daniela Iribarne
- Department of Microbiology and Molecular Genetics, University of Florida, Gainesville, Florida; and
| | - Bradley Bruggeman
- Department of Microbiology and Molecular Genetics, University of Florida, Gainesville, Florida; and
| | | | - Brian D. Harfe
- Department of Microbiology and Molecular Genetics, University of Florida, Gainesville, Florida; and
- Genetics Institute, University of Florida, Gainesville, Florida
| | - Keith P. Choe
- Department of Biology, University of Florida, Gainesville, Florida
- Genetics Institute, University of Florida, Gainesville, Florida
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71
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Rusu MC, Poalelungi CV, Vrapciu AD, Păduraru L, Didilescu AC, Stan CI. Anoctamin 1 Positive Esophageal Interstitial Cajal Cells in Late Stage Human Embryos. Anat Rec (Hoboken) 2013; 297:301-7. [DOI: 10.1002/ar.22837] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 09/21/2013] [Accepted: 10/18/2013] [Indexed: 12/14/2022]
Affiliation(s)
- Mugurel Constantin Rusu
- Division of Anatomy; Faculty of Dental Medicine; “Carol Davila” University of Medicine and Pharmacy; Bucharest Romania
- MEDCENTER - Center of Excellence in Laboratory Medicine and Pathology
| | - Cristian Viorel Poalelungi
- Department of Obstetrics and Gynaecology; "Dr.I.Cantacuzino" Hospital, "Carol Davila" University of Medicine and Pharmacy; Bucharest Romania
| | - Alexandra Diana Vrapciu
- Division of Anatomy; Faculty of Dental Medicine; “Carol Davila” University of Medicine and Pharmacy; Bucharest Romania
| | - Luminiţa Păduraru
- Division of Neonatology; “Mother and Child” Department; “Gr.T.Popa” University of Medicine and Pharmacy; Iasi Romania
| | - Andreea Cristiana Didilescu
- Division of Embryology; Faculty of Dental Medicine; “Carol Davila” University of Medicine and Pharmacy; Bucharest Romania
| | - Cristinel Ionel Stan
- Division of Anatomy; Faculty of Medicine; Gr.T.Popa” University of Medicine and Pharmacy; Iasi Romania
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72
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Functional reconstitution of a chloride channel bares its soul. Proc Natl Acad Sci U S A 2013; 110:19185-6. [PMID: 24235136 DOI: 10.1073/pnas.1319415110] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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73
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Dam VS, Boedtkjer DMB, Nyvad J, Aalkjaer C, Matchkov V. TMEM16A knockdown abrogates two different Ca(2+)-activated Cl (-) currents and contractility of smooth muscle in rat mesenteric small arteries. Pflugers Arch 2013; 466:1391-409. [PMID: 24162234 PMCID: PMC4062836 DOI: 10.1007/s00424-013-1382-1] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Revised: 10/10/2013] [Accepted: 10/10/2013] [Indexed: 12/30/2022]
Abstract
The presence of Ca2+-activated Cl− channels (CaCCs) in vascular smooth muscle cells (SMCs) is well established. Their molecular identity is, however, elusive. Two distinct Ca2+-activated Cl− currents (ICl(Ca)) were previously characterized in SMCs. We have shown that the cGMP-dependent ICl(Ca) depends on bestrophin expression, while the “classical” ICl(Ca) is not. Downregulation of bestrophins did not affect arterial contraction but inhibited the rhythmic contractions, vasomotion. In this study, we have used in vivo siRNA transfection of rat mesenteric small arteries to investigate the role of a putative CaCC, TMEM16A. Isometric force, [Ca2+]i, and SMC membrane potential were measured in isolated arterial segments. ICl(Ca) and GTPγS-induced nonselective cation current were measured in isolated SMCs. Downregulation of TMEM16A resulted in inhibition of both the cGMP-dependent ICl(Ca) and the “classical” ICl(Ca) in SMCs. TMEM16A downregulation also reduced expression of bestrophins. TMEM16A downregulation suppressed vasomotion both in vivo and in vitro. Downregulation of TMEM16A reduced agonist (noradrenaline and vasopressin) and K+-induced contractions. In accordance with the depolarizing role of CaCCs, TMEM16A downregulation suppressed agonist-induced depolarization and elevation in [Ca2+]i. Surprisingly, K+-induced depolarization was unchanged but Ca2+ entry was reduced. We suggested that this is due to reduced expression of the L-type Ca2+ channels, as observed at the mRNA level. Thus, the importance of TMEM16A for contraction is, at least in part, independent from membrane potential. This study demonstrates the significance of TMEM16A for two SMCs ICl(Ca) and vascular function and suggests an interaction between TMEM16A and L-type Ca2+ channels.
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Affiliation(s)
- Vibeke Secher Dam
- Department of Biomedicine, MEMBRANES, Aarhus University, Ole Worms Alle bygn.4, 1163, Aarhus, C 8000, Denmark
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74
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Anoctamin 1 induces calcium-activated chloride secretion and proliferation of renal cyst-forming epithelial cells. Kidney Int 2013; 85:1058-67. [PMID: 24152967 DOI: 10.1038/ki.2013.418] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Revised: 08/20/2013] [Accepted: 08/22/2013] [Indexed: 01/08/2023]
Abstract
Polycystic kidney diseases are characterized by multiple bilateral renal cysts that gradually enlarge and lead to a decline in renal function. Cyst enlargement is driven by transepithelial chloride secretion, stimulated by enhanced levels of cyclic adenosine monophosphate, which activates apical cystic fibrosis transmembrane conductance regulator chloride channels. However, chloride secretion by calcium-dependent chloride channels, activated through stimulation of purinergic receptors, also has a major impact. To identify the molecular basis of calcium-dependent chloride secretion in cyst expansion, we determined the role of anoctamin 1 and 6, two recently discovered calcium-activated chloride channels both of which are expressed in epithelial cells. We found that anoctamin 1, which plays a role in epithelial fluid secretion and proliferation, is strongly expressed in principal-like MDCK cells (PLCs) forming cysts within a collagen matrix, in an embryonic kidney cyst model, and in human autosomal dominant polycystic kidney disease tissue. Knockdown of anoctamin 1 but not anoctamin 6 strongly diminished the calcium-dependent chloride secretion of PLCs. Moreover, two inhibitors of anoctamin ion channels, tannic acid and a more selective inhibitor of anoctamin 1, significantly inhibited PLC cyst growth and cyst enlargement in an embryonic kidney cyst model. Knockdown of ANO1 by morpholino analogs also attenuated embryonic cyst growth. Thus, calcium-activated chloride secretion by anoctamin 1 appears to be a crucial component of renal cyst growth.
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75
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Jacobsen KS, Zeeberg K, Sauter DRP, Poulsen KA, Hoffmann EK, Schwab A. The role of TMEM16A (ANO1) and TMEM16F (ANO6) in cell migration. Pflugers Arch 2013; 465:1753-62. [PMID: 23832500 PMCID: PMC3898376 DOI: 10.1007/s00424-013-1315-z] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Revised: 06/14/2013] [Accepted: 06/15/2013] [Indexed: 12/30/2022]
Abstract
Members of the TMEM16 family have recently been described as Ca2+-activated Cl− channels. They have been implicated in cancer and appear to be associated with poor patient prognosis. Here, we investigate the role of TMEM16 channels in cell migration, which is largely unknown. We focused on TMEM16A and TMEM16F channels that have the highest expression of TMEM16 channels in Ehrlich Lettre ascites (ELA) cells. Due to the lack of specific pharmacological modulators, we employed a miRNA approach and stably knocked down the expression of TMEM16A and TMEM16F channels, respectively. Migration analysis shows that TMEM16A KD clones are affected in their directional migration, whereas TMEM16F KD clones show a 40 % reduced rate of cell migration. Moreover, TMEM16A KD clones have a smaller projected cell area, and they are rounder than TMEM16F KD clones. The morphological changes are linearly correlated with the directionality of cells. TMEM16A and TMEM16F, thus, have an important function in cell migration—TMEM16A in directional migration, TMEM16F in determination of the speed of migration. We conclude that TMEM16A and TMEM16F channels have a distinct impact on the steering and motor mechanisms of migrating ELA cells.
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Affiliation(s)
- K S Jacobsen
- Department of Biology, August Krogh Building, Universitetsparken 13, 2100, Copenhagen Ø, Denmark
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76
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Jeon JH, Paik SS, Chun MH, Oh U, Kim IB. Presynaptic Localization and Possible Function of Calcium-Activated Chloride Channel Anoctamin 1 in the Mammalian Retina. PLoS One 2013; 8:e67989. [PMID: 23840801 PMCID: PMC3693959 DOI: 10.1371/journal.pone.0067989] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2013] [Accepted: 05/23/2013] [Indexed: 11/18/2022] Open
Abstract
Calcium (Ca(2+))-activated chloride (Cl(-)) channels (CaCCs) play a role in the modulation of action potentials and synaptic responses in the somatodendritic regions of central neurons. In the vertebrate retina, large Ca(2+)-activated Cl(-) currents (ICl(Ca)) regulate synaptic transmission at photoreceptor terminals; however, the molecular identity of CaCCs that mediate ICl(Ca) remains unclear. The transmembrane protein, TMEM16A, also called anoctamin 1 (ANO1), has been recently validated as a CaCC and is widely expressed in various secretory epithelia and nervous tissues. Despite the fact that tmem16a was first cloned in the retina, there is little information on its cellular localization and function in the mammalian retina. In this study, we found that ANO1 was abundantly expressed as puncta in 2 synaptic layers. More specifically, ANO1 immunoreactivity was observed in the presynaptic terminals of various retinal neurons, including photoreceptors. ICl(Ca) was first detected in dissociated rod bipolar cells expressing ANO1. ICl(Ca) was abolished by treatment with the Ca(2+) channel blocker Co(2+), the L-type Ca(2+) channel blocker nifedipine, and the Cl(-) channel blockers 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB) and niflumic acid (NFA). More specifically, a recently discovered ANO1-selective inhibitor, T16Ainh-A01, and a neutralizing antibody against ANO1 inhibited ICl(Ca) in rod bipolar cells. Under a current-clamping mode, the suppression of ICl(Ca) by using NPPB and T16Ainh-A01 caused a prolonged Ca(2+) spike-like depolarization evoked by current injection in dissociated rod bipolar cells. These results suggest that ANO1 confers ICl(Ca) in retinal neurons and acts as an intrinsic regulator of the presynaptic membrane potential during synaptic transmission.
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Affiliation(s)
- Ji Hyun Jeon
- Department of Anatomy, College of Medicine, The Catholic University of Korea, Seoul, Korea
- Catholic Neuroscience Institute, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Sun Sook Paik
- Department of Anatomy, College of Medicine, The Catholic University of Korea, Seoul, Korea
- Catholic Neuroscience Institute, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Myung-Hoon Chun
- Department of Anatomy, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Uhtaek Oh
- Channel Research Center, College of Pharmacy, Seoul National University, Seoul, Korea
| | - In-Beom Kim
- Department of Anatomy, College of Medicine, The Catholic University of Korea, Seoul, Korea
- Catholic Neuroscience Institute, College of Medicine, The Catholic University of Korea, Seoul, Korea
- Catholic Institute for Applied Anatomy, College of Medicine, The Catholic University of Korea, Seoul, Korea
- * E-mail:
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77
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Ponissery Saidu S, Stephan AB, Talaga AK, Zhao H, Reisert J. Channel properties of the splicing isoforms of the olfactory calcium-activated chloride channel Anoctamin 2. ACTA ACUST UNITED AC 2013; 141:691-703. [PMID: 23669718 PMCID: PMC3664704 DOI: 10.1085/jgp.201210937] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Anoctamin (ANO)2 (or TMEM16B) forms a cell membrane Ca(2+)-activated Cl(-) channel that is present in cilia of olfactory receptor neurons, vomeronasal microvilli, and photoreceptor synaptic terminals. Alternative splicing of Ano2 transcripts generates multiple variants with the olfactory variants skipping exon 14 and having alternative splicing of exon 4. In the present study, 5' rapid amplification of cDNA ends analysis was conducted to characterize the 5' end of olfactory Ano2 transcripts, which showed that the most abundant Ano2 transcripts in the olfactory epithelium contain a novel starting exon that encodes a translation initiation site, whereas transcripts of the publically available sequence variant, which has an alternative and longer 5' end, were present in lower abundance. With two alternative starting exons and alternative splicing of exon 4, four olfactory ANO2 isoforms are thus possible. Patch-clamp experiments in transfected HEK293T cells expressing these isoforms showed that N-terminal sequences affect Ca(2+) sensitivity and that the exon 4-encoded sequence is required to form functional channels. Coexpression of the two predominant isoforms, one with and one without the exon 4 sequence, as well as coexpression of the two rarer isoforms showed alterations in channel properties, indicating that different isoforms interact with each other. Furthermore, channel properties observed from the coexpression of the predominant isoforms better recapitulated the native channel properties, suggesting that the native channel may be composed of two or more splicing isoforms acting as subunits that together shape the channel properties.
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78
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Kmit A, van Kruchten R, Ousingsawat J, Mattheij NJA, Senden-Gijsbers B, Heemskerk JWM, Schreiber R, Bevers EM, Kunzelmann K. Calcium-activated and apoptotic phospholipid scrambling induced by Ano6 can occur independently of Ano6 ion currents. Cell Death Dis 2013; 4:e611. [PMID: 23618909 PMCID: PMC3668637 DOI: 10.1038/cddis.2013.135] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Revised: 02/16/2013] [Accepted: 03/11/2013] [Indexed: 11/17/2022]
Abstract
Immune cells and platelets maintain plasma membrane phospholipid asymmetry. Upon activation, this asymmetry is disrupted by phospholipid scrambling (PS), which is a major step during activation of immune cells, hemostasis and apoptosis. Anoctamin 6 (Ano6; TMEM16F) causes chloride (Cl(-)) and cation currents and is required for Ca(2+)-dependent PS. It is defective in blood cells from patients with Scott syndrome, a rare bleeding disorder. We examined if Cl(-) currents and PS are related, whether both processes are Ca(2+) dependent, and whether Ca(2+)-independent scrambling during intrinsic and extrinsic apoptosis is controlled by Ano6. Ca(2+) increase by ionomycin activated Ano6 Cl(-) currents and PS in normal lymphocytes, but not in B-lymphocytes from two different patients with Scott syndrome. Fas ligand (FasL) did not increase intracellular Ca(2+), but activated Cl(-) currents in normal but not in Scott lymphocytes. Whole-cell currents were inhibited by Cl(-) channel blockers and by siRNA knockdown of Ano6. In contrast, intrinsic mitochondrial apoptosis by ABT-737 did not induce Cl(-) currents in lymphocytes. PS was not inhibited by blockers of Ano6 or removal of Cl(-) ions. Remarkably, Ca(2+)-independent scrambling due to extrinsic (FasL) or intrinsic (ABT-737) apoptosis was unchanged in Scott cells. We conclude that: (i) Ano6 Cl(-) currents are activated by increase in cytosolic Ca(2+), or Ca(2+) independent by stimulation of Fas receptors; (ii) Ca(2+)-dependent PS induced by Ano6 does not require Cl(-) currents; (iii) Ca(2+)-independent PS does not require Ano6; (iv) Ano6 is necessary for Ca(2+)-dependent PS, but not by increasing intracellular Ca(2+).
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Affiliation(s)
- A Kmit
- Institut für Physiologie, Universität Regensburg, Regensburg, Germany
| | - R van Kruchten
- Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, The Netherlands
| | - J Ousingsawat
- Institut für Physiologie, Universität Regensburg, Regensburg, Germany
| | - N J A Mattheij
- Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, The Netherlands
| | - B Senden-Gijsbers
- Department of Internal Medicine, Division of Haematology, Maastricht University Medical Center, Maastricht, The Netherlands
| | - J W M Heemskerk
- Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, The Netherlands
| | - R Schreiber
- Institut für Physiologie, Universität Regensburg, Regensburg, Germany
| | - E M Bevers
- Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, The Netherlands
| | - K Kunzelmann
- Institut für Physiologie, Universität Regensburg, Regensburg, Germany
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79
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Adomaviciene A, Smith KJ, Garnett H, Tammaro P. Putative pore-loops of TMEM16/anoctamin channels affect channel density in cell membranes. J Physiol 2013; 591:3487-505. [PMID: 23613533 DOI: 10.1113/jphysiol.2013.251660] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The recently identified TMEM16/anoctamin protein family includes Ca(2+)-activated anion channels (TMEM16A, TMEM16B), a cation channel (TMEM16F) and proteins with unclear function. TMEM16 channels consist of eight putative transmembrane domains (TMs) with TM5-TM6 flanking a re-entrant loop thought to form the pore. In TMEM16A this region has also been suggested to contain residues involved in Ca(2+) binding. The role of the putative pore-loop of TMEM16 channels was investigated using a chimeric approach. Heterologous expression of either TMEM16A or TMEM16B resulted in whole-cell anion currents with very similar conduction properties but distinct kinetics and degrees of sensitivity to Ca(2+). Furthermore, whole-cell currents mediated by TMEM16A channels were ∼six times larger than TMEM16B-mediated currents. Replacement of the putative pore-loop of TMEM16A with that of TMEM16B (TMEM16A-B channels) reduced the currents by ∼six-fold, while the opposite modification (TMEM16B-A channels) produced a ∼six-fold increase in the currents. Unexpectedly, these changes were not secondary to variations in channel gating by Ca(2+) or voltage, nor were they due to changes in single-channel conductance. Instead, they depended on the number of functional channels present on the plasma membrane. Generation of additional, smaller chimeras within the putative pore-loop of TMEM16A and TMEM16B led to the identification of a region containing a non-canonical trafficking motif. Chimeras composed of the putative pore-loop of TMEM16F transplanted into the TMEM16A protein scaffold did not conduct anions or cations. These data suggest that the putative pore-loop does not form a complete, transferable pore domain. Furthermore, our data reveal an unexpected role for the putative pore-loop of TMEM16A and TMEM16B channels in the control of the whole-cell Ca(2+)-activated Cl(-) conductance.
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Affiliation(s)
- Aiste Adomaviciene
- Faculty of Life Sciences, The University of Manchester, 46 Grafton Street, Manchester M13 9NT, UK
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80
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Yamazaki J, Okamura K, Uehara K, Hatta M. CLCA splicing isoform associated with adhesion through β1-integrin and its scaffolding protein: specific expression in undifferentiated epithelial cells. J Biol Chem 2013; 288:4831-43. [PMID: 23297403 DOI: 10.1074/jbc.m112.396481] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We previously found that a rat CLCA homologue (rCLCA-f) modulates Ca(2+)-dependent Cl(-) transport in the ductal cells of the rat submandibular gland. CLCA proteins have been shown to be multifunctional, with roles in, for example, cell adhesion. Here, we describe the mRNA and protein expressions of a splicing isoform of rat rCLCA (rCLCA-t). This isoform is a 514-amino acid protein containing a C-terminal 59-amino acid that is distinct from the rCLCA-f sequence. Immunohistochemistry revealed rCLCA-t to be located in the basal cells of the rat submandibular gland excretory duct and the stratum basale of rat epidermis, whereas rCLCA-f was detected in cells during the process of differentiation. In a heterologous expression system, rCLCA-t was found to be a membrane protein present predominantly in the perinuclear region, and not to be either present on the cell surface or secreted. rCLCA-t failed to enhance ionomycin-induced Cl(-) conductance (unlike rCLCA-f). When compared with rCLCA-f, it weakened cell attachment to a greater extent and in a manner that was evidently modulated by intracellular Ca(2+), protein kinase C, and β(1)-integrin. rCLCA-t was found to associate with RACK1 (receptor for activated C kinase) and to reduce expression of mature β(1)-integrin. Treatment of rat skin with rCLCA-t siRNA increased the expression of β(1)-integrin in the stratum basale of the epidermis. These results are consistent with cell-specific splicing of rCLCA mRNA playing a role in the modulation of the adhesive potential of undifferentiated epithelial cells.
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Affiliation(s)
- Jun Yamazaki
- Department of Physiological Science and Molecular Biology, Fukuoka Dental College, Sawara-ku, Fukuoka 814-0193, Japan.
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81
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Tian Y, Schreiber R, Wanitchakool P, Kongsuphol P, Sousa M, Uliyakina I, Palma M, Faria D, Traynor-Kaplan AE, Fragata JI, Amaral MD, Kunzelmann K. Control of TMEM16A by INO-4995 and other inositolphosphates. Br J Pharmacol 2013; 168:253-65. [PMID: 22946960 PMCID: PMC3570019 DOI: 10.1111/j.1476-5381.2012.02193.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Revised: 07/06/2012] [Accepted: 07/31/2012] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND AND PURPOSE Ca(2+)-dependent Cl(-) secretion (CaCC) in airways and other tissues is due to activation of the Cl(-) channel TMEM16A (anoctamin 1). Earlier studies suggested that Ca(2+) -activated Cl(-) channels are regulated by membrane lipid inositol phosphates, and that 1-O-octyl-2-O-butyryl-myo-inositol 3,4,5,6-tetrakisphosphate octakis(propionoxymethyl) ester (INO-4995) augments CaCC. Here we examined whether TMEM16A is the target for INO-4995 and if the channel is regulated by inositol phosphates. EXPERIMENTAL APPROACH The effects of INO-4995 on CaCC were examined in overexpressing HEK293, colonic and primary airway epithelial cells as well as Xenopus oocytes. We used patch clamping, double electrode voltage clamp and Ussing chamber techniques. KEY RESULTS We found that INO-4995 directly activates a TMEM16A whole cell conductance of 6.1 ± 0.9 nS pF(-1) in overexpressing cells. The tetrakisphosphates Ins(3,4,5,6)P(4) or Ins(1,3,4,5)P(4) and enzymes controlling levels of InsP(4) or PIP(2) and PIP(3) had no effects on the magnitude or kinetics of TMEM16A currents. In contrast in Xenopus oocytes, human airways and colonic cells, which all express TMEM16A endogenously, Cl(-) currents were not acutely activated by INO-4995. However incubation with INO-4995 augmented 1.6- to 4-fold TMEM16A-dependent Cl(-) currents activated by ionomycin or ATP, while intracellular Ca(2+) signals were not affected. The potentiating effect of INO-4995 on transient ATP-activated TMEM16A-currents in cystic fibrosis (CF) airways was twice of that observed in non-CF airways. CONCLUSIONS AND IMPLICATIONS These data indicate that TMEM16A is the target for INO-4995, although the mode of action appears different for overexpressed and endogenous channels. INO-4995 may be useful for the treatment of CF lung disease.
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Key Words
- ino-4995
- ino4913
- anoctamin 1
- tmem16a
- inositol phosphates
- ins(3,4,5,6)p4
- inositol 3,4,5,6-tetrakisphosphate
- ins(1,3,4,5)p4
- inositol 1,3,4,5-tetrakisphosphate
- ca2+-activated cl− channels
- cacc
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Affiliation(s)
- Yuemin Tian
- Institut für Physiologie, Universität RegensburgRegensburg, Germany
| | - Rainer Schreiber
- Institut für Physiologie, Universität RegensburgRegensburg, Germany
| | | | | | - Marisa Sousa
- Faculty of Sciences, BioFIG – Centre for Biodiversity, Functional and Integrative Genomics, University of LisboaLisboa, Portugal
- Department of Genetics, National Institute of HealthLisboa, Portugal
| | - Inna Uliyakina
- Faculty of Sciences, BioFIG – Centre for Biodiversity, Functional and Integrative Genomics, University of LisboaLisboa, Portugal
- Department of Genetics, National Institute of HealthLisboa, Portugal
| | - Marta Palma
- Faculty of Sciences, BioFIG – Centre for Biodiversity, Functional and Integrative Genomics, University of LisboaLisboa, Portugal
| | - Diana Faria
- Institut für Physiologie, Universität RegensburgRegensburg, Germany
| | - Alexis E Traynor-Kaplan
- ISM TherapeuticsSeattle, WA, USA
- Division of Gastroenterology, Department of Medicine, University of WashingtonSeattle, WA, USA
| | - José I Fragata
- Department Cardio-Thoracic Surgery, Hospital de Santa MartaLisboa, Portugal
| | - Margarida D Amaral
- Faculty of Sciences, BioFIG – Centre for Biodiversity, Functional and Integrative Genomics, University of LisboaLisboa, Portugal
- Department of Genetics, National Institute of HealthLisboa, Portugal
| | - Karl Kunzelmann
- Institut für Physiologie, Universität RegensburgRegensburg, Germany
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82
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Tian Y, Schreiber R, Kunzelmann K. Anoctamins are a family of Ca2+-activated Cl- channels. J Cell Sci 2012; 125:4991-8. [PMID: 22946059 DOI: 10.1242/jcs.109553] [Citation(s) in RCA: 128] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Anoctamin 1 (Ano1; TMEM16A) and anoctamin 2 (Ano2; TMEM16B) are novel Cl(-) channels transiently activated by an increase in intracellular Ca(2+). These channels are essential for epithelial Cl(-) secretion, smooth muscle peristalsis and olfactory signal transduction. They are central to inherited diseases and cancer and can act as heat sensors. Surprisingly, another member of this protein family, Ano6, operates as a Ca(2+)-activated phospholipid scramblase, and others were reported as intracellular proteins. It is therefore unclear whether anoctamins constitute a family of Ca(2+)-activated Cl(-) channels, or are proteins with heterogeneous functions. Using whole-cell patch clamping we demonstrate that Ano4-10 are all able to produce transient Ca(2+)-activated Cl(-) currents when expressed in HEK293 cells. Although some anoctamins (Ano1, 2, 4, 6, 7) were found to be well expressed in the plasma membrane, others (Ano8, 9, 10) show rather poor membrane expression and were mostly retained in the cytosol. The transient nature of the Cl(-) currents was demonstrated to be independent of intracellular Ca(2+) levels. We show that inactivation of Ano1 currents occurs in the continuous presence of elevated Ca(2+) concentrations, possibly by calmodulin-dependent kinase. The present results demonstrate that anoctamins are a family of Ca(2+)-activated Cl(-) channels, which also induce permeability for cations. They may operate as Cl(-) channels located in the plasma membrane or in intracellular compartments. These results increase our understanding of the physiological significance of anoctamins and their role in disease.
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Affiliation(s)
- Yuemin Tian
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, 93053 Regensburg, Germany
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83
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Zeng F, Wind N, McClenaghan C, Verkuyl JM, Watson RP, Nash MS. GPR39 is coupled to TMEM16A in intestinal fibroblast-like cells. PLoS One 2012; 7:e47686. [PMID: 23133519 PMCID: PMC3485058 DOI: 10.1371/journal.pone.0047686] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Accepted: 09/18/2012] [Indexed: 12/04/2022] Open
Abstract
GPR39 is a GPCR implicated as a regulator of gastrointestinal motility, although the mechanism remains elusive. Here, we report that GPR39 is expressed by a specific cell population cultured from mouse small intestine muscle layers, which was subsequently identified as fibroblast-like cells (FLCs) that have recently been shown to modulate gut motility. Application of the GPR39 agonist, Zn2+, induced large currents and membrane depolarization in FLCs cultured from wild-type mice, but not Gpr39−/− mice. This Zn2+-induced current could be suppressed by application of a TMEM16A antagonist, CaCCinh-A01, or by silencing Tmem16a expression. These data suggest that GPR39 might modulate gut motility via regulating TMEM16A function in FLCs.
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Affiliation(s)
- Fanning Zeng
- Gastrointestinal Disease Area, Novartis Horsham Research Centre, Horsham, United Kingdom.
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84
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Abstract
Luminal acidification is of pivotal importance for the physiology of the secretory and endocytic pathways and its diverse trafficking events. Acidification by the proton-pumping V-ATPase requires charge compensation by counterion currents that are commonly attributed to chloride. The molecular identification of intracellular chloride transporters and the improvement of methodologies for measuring intraorganellar pH and chloride have facilitated the investigation of the physiology of vesicular chloride transport. New data question the requirement of chloride for pH regulation of various organelles and furthermore ascribe functions to chloride that are beyond merely electrically shunting the proton pump. This review surveys the currently established and proposed intracellular chloride transporters and gives an overview of membrane-trafficking steps that are affected by the perturbation of chloride transport. Finally, potential mechanisms of membrane-trafficking modulation by chloride are discussed and put into the context of organellar ion homeostasis in general.
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Affiliation(s)
- Tobias Stauber
- Physiology and Pathology of Ion Transport, Leibniz-Institut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin, 13125 Berlin, Germany.
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85
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Ruiz C, Martins JR, Rudin F, Schneider S, Dietsche T, Fischer CA, Tornillo L, Terracciano LM, Schreiber R, Bubendorf L, Kunzelmann K. Enhanced expression of ANO1 in head and neck squamous cell carcinoma causes cell migration and correlates with poor prognosis. PLoS One 2012; 7:e43265. [PMID: 22912841 PMCID: PMC3422276 DOI: 10.1371/journal.pone.0043265] [Citation(s) in RCA: 130] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Accepted: 07/18/2012] [Indexed: 12/23/2022] Open
Abstract
Head and neck squamous cell carcinoma (HNSCC) has the potential for early metastasis and is associated with poor survival. Ano1 (Dog1) is an established and sensitive marker for the diagnosis of gastrointestinal stromal tumors (GIST) and has recently been identified as a Ca2+ activated Cl− channel. Although the ANO1 gene is located on the 11q13 locus, a region which is known to be amplified in different types of human carcinomas, a detailed analysis of Ano1 amplification and expression in HNSCC has not been performed. It is thus still unclear how Ano1 contributes to malignancy in HNSCC. We analyzed genomic amplification of the 11q13 locus and Ano1 together with Ano1-protein expression in a large collection of HNSCC samples. We detected a highly significant correlation between amplification and expression of Ano1 and showed that HNSCC patients with Ano1 protein expression have a poor overall survival. We further analyzed the expression of the Ano1 protein in more than 4′000 human samples from 80 different tumor types and 76 normal tissue types and detected that besides HNSCC and GISTs, Ano1 was rarely expressed in other tumor samples or healthy human tissues. In HNSCC cell lines, expression of Ano1 caused Ca2+ activated Cl− currents, which induced cell motility and cell migration in wound healing and in real time migration assays, respectively. In contrast, knockdown of Ano1 did not affect intracellular Ca2+ signaling and surprisingly did not reduce cell proliferation in BHY cells. Further, expression and activity of Ano1 strongly correlated with the ability of HNSCC cells to regulate their volume. Thus, poor survival in HNSCC patients is correlated with the presence of Ano1. Our results further suggest that Ano1 facilitates regulation of the cell volume and causes cell migration, which both can contribute to metastatic progression in HNSCC.
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Affiliation(s)
- Christian Ruiz
- Institute for Pathology, University Hospital Basel, Basel, Switzerland.
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86
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Magri F, Bo RD, D’Angelo MG, Sciacco M, Gandossini S, Govoni A, Napoli L, Ciscato P, Fortunato F, Brighina E, Bonato S, Bordoni A, Lucchini V, Corti S, Moggio M, Bresolin N, Comi GP. Frequency and characterisation of anoctamin 5 mutations in a cohort of Italian limb-girdle muscular dystrophy patients. Neuromuscul Disord 2012; 22:934-43. [PMID: 22742934 PMCID: PMC3500692 DOI: 10.1016/j.nmd.2012.05.001] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Revised: 04/30/2012] [Accepted: 05/03/2012] [Indexed: 12/03/2022]
Abstract
Limb-girdle muscular dystrophy (LGMD) 2L, caused by mutations in the anoctamin 5 (ANO5) gene, is the third most common LGMD in Northern and Central Europe, where the c.191dupA mutation causes the majority of cases. We evaluated data from 228 Italian LGMD patients to determine the prevalence of LGMD2L and the c.191dupA mutation, and to describe the clinical, muscle biopsy, and magnetic resonance imaging findings in these patients. Forty-three patients who lacked molecular diagnosis were studied for ANO5 mutations, and four novel mutations were found in three probands. Only one proband carried the c.191dupA mutation, which was compound heterozygous with c.2516T>G. Two probands were homozygous for the c.1627dupA and c.397A>T mutations, respectively, while a fourth proband had a compound heterozygous status (c.220C>T and c.1609T>C). Therefore occurrence and molecular epidemiology of LGMD2L in this Italian cohort differed from those observed in other European countries. ANO5 mutations accounted for ∼2% of our sample. Affected patients exhibited benign progression with variable onset and an absence of cardiac and respiratory impairment; muscle biopsy generally showed mild signs, except when performed on the quadriceps muscles; MRI showed predominant involvement of the posterior thigh. Overall these common clinical, morphological and imaging findings could be useful in differential diagnosis.
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Affiliation(s)
- Francesca Magri
- Dino Ferrari Centre, Department of Neurological Sciences, University of Milan, IRCCS Foundation Ca’ Granda, Ospedale Maggiore Policlinico, Milan, Italy
| | - Roberto Del Bo
- Dino Ferrari Centre, Department of Neurological Sciences, University of Milan, IRCCS Foundation Ca’ Granda, Ospedale Maggiore Policlinico, Milan, Italy
| | | | - Monica Sciacco
- Dino Ferrari Centre, Department of Neurological Sciences – Neuromuscular Unit University of Milan, IRCCS Foundation Ca’ Granda, Ospedale Maggiore Policlinico, Milan, Italy
| | | | - Alessandra Govoni
- Dino Ferrari Centre, Department of Neurological Sciences, University of Milan, IRCCS Foundation Ca’ Granda, Ospedale Maggiore Policlinico, Milan, Italy
| | - Laura Napoli
- Dino Ferrari Centre, Department of Neurological Sciences – Neuromuscular Unit University of Milan, IRCCS Foundation Ca’ Granda, Ospedale Maggiore Policlinico, Milan, Italy
| | - Patrizia Ciscato
- Dino Ferrari Centre, Department of Neurological Sciences – Neuromuscular Unit University of Milan, IRCCS Foundation Ca’ Granda, Ospedale Maggiore Policlinico, Milan, Italy
| | - Francesco Fortunato
- Dino Ferrari Centre, Department of Neurological Sciences, University of Milan, IRCCS Foundation Ca’ Granda, Ospedale Maggiore Policlinico, Milan, Italy
| | - Erika Brighina
- Scientific Institute IRCCS E. Medea, Bosisio Parini, Lecco, Italy
| | - Sara Bonato
- Scientific Institute IRCCS E. Medea, Bosisio Parini, Lecco, Italy
| | - Andreina Bordoni
- Dino Ferrari Centre, Department of Neurological Sciences, University of Milan, IRCCS Foundation Ca’ Granda, Ospedale Maggiore Policlinico, Milan, Italy
| | - Valeria Lucchini
- Dino Ferrari Centre, Department of Neurological Sciences – Neuromuscular Unit University of Milan, IRCCS Foundation Ca’ Granda, Ospedale Maggiore Policlinico, Milan, Italy
| | - Stefania Corti
- Dino Ferrari Centre, Department of Neurological Sciences, University of Milan, IRCCS Foundation Ca’ Granda, Ospedale Maggiore Policlinico, Milan, Italy
| | - Maurizio Moggio
- Dino Ferrari Centre, Department of Neurological Sciences – Neuromuscular Unit University of Milan, IRCCS Foundation Ca’ Granda, Ospedale Maggiore Policlinico, Milan, Italy
| | - Nereo Bresolin
- Dino Ferrari Centre, Department of Neurological Sciences, University of Milan, IRCCS Foundation Ca’ Granda, Ospedale Maggiore Policlinico, Milan, Italy
- Scientific Institute IRCCS E. Medea, Bosisio Parini, Lecco, Italy
| | - Giacomo Pietro Comi
- Dino Ferrari Centre, Department of Neurological Sciences, University of Milan, IRCCS Foundation Ca’ Granda, Ospedale Maggiore Policlinico, Milan, Italy
- Corresponding author. Adderess: Dipartimento di Scienze Neurologiche, Università di Milano, Padiglione Ponti, Ospedale Maggiore Policlinico, Via Francesco Sforza 35, 20122 Milan, Italy. Tel.: +39 02 55033817; fax: +39 02 50320430.
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87
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Cenedese V, Betto G, Celsi F, Cherian OL, Pifferi S, Menini A. The voltage dependence of the TMEM16B/anoctamin2 calcium-activated chloride channel is modified by mutations in the first putative intracellular loop. ACTA ACUST UNITED AC 2012; 139:285-94. [PMID: 22412191 PMCID: PMC3315145 DOI: 10.1085/jgp.201110764] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Ca2+-activated Cl− channels (CaCCs) are involved in several physiological processes. Recently, TMEM16A/anoctamin1 and TMEM16B/anoctamin2 have been shown to function as CaCCs, but very little information is available on the structure–function relations of these channels. TMEM16B is expressed in the cilia of olfactory sensory neurons, in microvilli of vomeronasal sensory neurons, and in the synaptic terminals of retinal photoreceptors. Here, we have performed the first site-directed mutagenesis study on TMEM16B to understand the molecular mechanisms of voltage and Ca2+ dependence. We have mutated amino acids in the first putative intracellular loop and measured the properties of the wild-type and mutant TMEM16B channels expressed in HEK 293T cells using the whole cell voltage-clamp technique in the presence of various intracellular Ca2+ concentrations. We mutated E367 into glutamine or deleted the five consecutive glutamates 386EEEEE390 and 399EYE401. The EYE deletion did not significantly modify the apparent Ca2+ dependence nor the voltage dependence of channel activation. E367Q and deletion of the five glutamates did not greatly affect the apparent Ca2+ affinity but modified the voltage dependence, shifting the conductance–voltage relations toward more positive voltages. These findings indicate that glutamates E367 and 386EEEEE390 in the first intracellular putative loop play an important role in the voltage dependence of TMEM16B, thus providing an initial structure–function study for this channel.
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Affiliation(s)
- Valentina Cenedese
- Neurobiology Sector, International School for Advanced Studies, and Italian Institute of Technology, SISSA Unit, 34136 Trieste, Italy
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88
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Yu K, Duran C, Qu Z, Cui YY, Hartzell HC. Explaining calcium-dependent gating of anoctamin-1 chloride channels requires a revised topology. Circ Res 2012; 110:990-9. [PMID: 22394518 DOI: 10.1161/circresaha.112.264440] [Citation(s) in RCA: 145] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
RATIONALE Ca2+ -activated Cl channels play pivotal roles in the cardiovascular system. They regulate vascular smooth muscle tone and participate in cardiac action potential repolarization in some species. Ca2+ -activated Cl channels were recently discovered to be encoded by members of the anoctamin (Ano, also called Tmem16) superfamily, but the mechanisms of Ano1 gating by Ca2+ remain enigmatic. OBJECTIVE The objective was to identify regions of Ano1 involved in channel gating by Ca2+. METHODS AND RESULTS The Ca2+ sensitivity of Ano1 was estimated from rates of current activation, and deactivation in excised patches rapidly switched between zero and high Ca2+ on the cytoplasmic side. Mutation of glutamates E702 and E705 dramatically altered Ca2+ sensitivity. E702 and E705 are predicted to be in an extracellular loop, but antigenic epitopes introduced into this loop are not accessible to extracellular antibodies, suggesting this loop is intracellular. Cytoplasmically applied membrane-impermeant sulfhydryl reagents alter the Ca2+ sensitivity of Ano1 E702C and E705C as expected if E702 and E705 are intracellular. Substituted cysteine accessibility mutagenesis of the putative re-entrant loop suggests that E702 and E705 are located adjacent to the Cl conduction pathway. CONCLUSIONS We propose an alternative model of Ano1 topology based on mutagenesis, epitope accessibility, and cysteine-scanning accessibility. These data contradict the popular re-entrant loop model by showing that the putative fourth extracellular loop (ECL 4) is intracellular and may contain a Ca2+ binding site. These studies provide new perspectives on regulation of Ano1 by Ca2+.
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Affiliation(s)
- Kuai Yu
- Department of Cell Biology, Emory University School of Medicine, 615 Michael St, Atlanta, GA 30322, USA
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89
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Lewis R, Feetham CH, Barrett-Jolley R. Cell volume regulation in chondrocytes. Cell Physiol Biochem 2011; 28:1111-22. [PMID: 22179000 DOI: 10.1159/000335847] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/05/2011] [Indexed: 11/19/2022] Open
Abstract
Chondrocytes are the cells within cartilage which produce and maintain the extracellular matrix. Volume regulation in these cells is vital to their function and occurs in several different physiological and pathological contexts. Firstly, chondrocytes exist within an environment of changing osmolarity and compressive loads. Secondly, in osteoarthritic joint failure, cartilage water content changes and there is a notable increase in chondrocyte apoptosis. Thirdly, endochondral ossification requires chondrocyte swelling in association with hypertrophy. Regulatory volume decrease (RVD) and regulatory volume increase (RVI) have both been observed in articular chondrocytes and this review focuses on the mechanisms identified to account for these. There has been evidence so far to suggest TRPV4 is central to RVD; however other elements of the pathway have not yet been identified. Unlike RVD, RVI appears less robust in articular chondrocytes and there have been fewer mechanistic studies; the primary focus being on the Na(+)-K(+)-2Cl(-) co-transporter. The clinical significance of chondrocyte volume regulation remains unproven. Importantly however, transcript abundances of several ion channels implicated in volume control are changed in chondrocytes from osteoarthritic cartilage. A critical question is whether disturbances of volume regulation mechanisms lead to, result from or are simply coincidental to cartilage damage.
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Affiliation(s)
- Rebecca Lewis
- Department of Musculoskeletal Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool, UK
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90
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Sancho M, García-Pascual A, Triguero D. Presence of the Ca2+-activated chloride channel anoctamin 1 in the urethra and its role in excitatory neurotransmission. Am J Physiol Renal Physiol 2011; 302:F390-400. [PMID: 22114201 DOI: 10.1152/ajprenal.00344.2011] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We investigated the cellular distribution of the calcium-activated chloride channel (CaCC), anoctamin 1, in the urethra of mice, rats, and sheep by both immunofluorescence and PCR. We studied its role in urethral contractility by examining the effects of chloride-free medium and of several CaCC inhibitors on noradrenergic and cholinergic excitatory responses, and on nitrergic relaxations in urethral preparations. In all species analyzed, CaCC played a key role in urethral contractions, influencing smooth muscle cells activated by increases in intracellular calcium, probably due to calcium influx but with a minor contribution by IP(3)-mediated calcium release. The participation of CaCC in relaxant responses was negligible. Strong anoctamin 1 immunoreactivity was detected in the smooth muscle cells and urothelia of sheep, rat, and mouse urethra, but not in the interstitial cells of Cajal (ICC) in any of these species. RT-PCR confirmed the expression of anoctamin 1 mRNA in the rat urethra. This anoctamin 1 in urethral smooth muscle probably mediates the activity of chloride in contractile responses in different species, However, the lack of anoctamin 1 in ICCs challenges its proposed role in regulating urethral contractility in a manner similar to that observed in the gut.
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Affiliation(s)
- Maria Sancho
- Dept. of Physiology, Veterinary School, Madrid, Spain
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Pifferi S, Cenedese V, Menini A. Anoctamin 2/TMEM16B: a calcium-activated chloride channel in olfactory transduction. Exp Physiol 2011; 97:193-9. [DOI: 10.1113/expphysiol.2011.058230] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Kunzelmann K, Schreiber R, Kmit A, Jantarajit W, Martins JR, Faria D, Kongsuphol P, Ousingsawat J, Tian Y. Expression and function of epithelial anoctamins. Exp Physiol 2011; 97:184-92. [PMID: 21908539 DOI: 10.1113/expphysiol.2011.058206] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Endogenous Ca(2+)-activated Cl(-) currents (CaCCs) are abundant and present in very different cell types. Very good evidence has been provided that endogenous CaCC is produced by anoctamin 1 (Ano1) and Ano2. Insight into the physiological role of anoctamins has been provided for Ano1, Ano2 and Ano6; however, the physiological role of the other seven members of the anoctamin family remains obscure. Anoctamins 1 and 2 may operate as individual Ca(2+)-sensitive channel proteins or may require accessory subunits for complete function. We find that overexpressed Ano1 has properties resembling all those of endogenous CaCCs, although with some noticeable biophysical and regulatory differences when compared with endogenous channels. Apart from Ano1 and Ano2, expression of Ano6 also produces a Cl(-) conductance. Depending on the cellular background, Ano6 currents may have variable properties. Anoctamins 1 and 6 are frequent in epithelial cells, often coexpressed together with Ano8, Ano9 and Ano10. Most available data on anoctamins were obtained from mouse tissues and from cultured cells, which may not be representative of native human tissues.
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Affiliation(s)
- Karl Kunzelmann
- Universität Regensburg, Institut für Physiologie, Universitätsstraße 31, Regensburg, Germany.
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