101
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Falzone ME, Malvezzi M, Lee BC, Accardi A. Known structures and unknown mechanisms of TMEM16 scramblases and channels. J Gen Physiol 2018; 150:933-947. [PMID: 29915161 PMCID: PMC6028493 DOI: 10.1085/jgp.201711957] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Accepted: 05/29/2018] [Indexed: 12/25/2022] Open
Abstract
Falzone et al. interpret the mechanisms underlying the activity of TMEM16 family members from recent structural and functional work. The TMEM16 family of membrane proteins is composed of both Ca2+-gated Cl− channels and Ca2+-dependent phospholipid scramblases. The functional diversity of TMEM16s underlies their involvement in numerous signal transduction pathways that connect changes in cytosolic Ca2+ levels to cellular signaling networks. Indeed, defects in the function of several TMEM16s cause a variety of genetic disorders, highlighting their fundamental pathophysiological importance. Here, we review how our mechanistic understanding of TMEM16 function has been shaped by recent functional and structural work. Remarkably, the recent determination of near-atomic-resolution structures of TMEM16 proteins of both functional persuasions has revealed how relatively minimal rearrangements in the substrate translocation pathway are sufficient to precipitate the dramatic functional differences that characterize the family. These structures, when interpreted in the light of extensive functional analysis, point to an unusual mechanism for Ca2+-dependent activation of TMEM16 proteins in which substrate permeation is regulated by a combination of conformational rearrangements and electrostatics. These breakthroughs pave the way to elucidate the mechanistic bases of ion and lipid transport by the TMEM16 proteins and unravel the molecular links between these transport activities and their function in human pathophysiology.
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Affiliation(s)
- Maria E Falzone
- Department of Biochemistry, Weill Cornell Medical School, New York, NY
| | - Mattia Malvezzi
- Department of Anesthesiology, Weill Cornell Medical School, New York, NY
| | - Byoung-Cheol Lee
- Department of Anesthesiology, Weill Cornell Medical School, New York, NY
| | - Alessio Accardi
- Department of Biochemistry, Weill Cornell Medical School, New York, NY .,Department of Anesthesiology, Weill Cornell Medical School, New York, NY.,Department of Physiology, Biophysics and Systems Biology, Weill Cornell Medical School, New York, NY
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102
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Inhibition of ANO1/TMEM16A induces apoptosis in human prostate carcinoma cells by activating TNF-α signaling. Cell Death Dis 2018; 9:703. [PMID: 29899325 PMCID: PMC5999606 DOI: 10.1038/s41419-018-0735-2] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2017] [Revised: 04/23/2018] [Accepted: 05/21/2018] [Indexed: 12/16/2022]
Abstract
Overexpression of the Ca2+-activated chloride channel ANO1/TMEM16A is implicated in tumorigenesis, and inhibition of ANO1 overexpression suppresses xenograft tumor growth and invasiveness. However, the underlying molecular mechanism for ANO1 inhibition in suppression of tumorigenesis remains unknown. Here, we show that silencing or inhibition of endogenous ANO1 inhibits cell growth, induces apoptosis and upregulates TNF-α expression in prostate cancer PC-3 cells. Enhancement of TNF-α signaling by ANO1 knockdown leads to upregulation of phosphorylated Fas-associated protein with death domain and caspase activation. Furthermore, silencing of ANO1 inhibits growth of PC-3 xenograft tumors in nude mice and induces apoptosis in tumors via upregulation of TNF-α signaling. Taken together, our findings provide mechanistic insight into promoting apoptosis in prostate cancer cells by ANO1 inhibition through upregulation of TNF-α signaling.
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103
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Molinski SV, Ahmadi S, Ip W, Ouyang H, Villella A, Miller JP, Lee PS, Kulleperuma K, Du K, Di Paola M, Eckford PD, Laselva O, Huan LJ, Wellhauser L, Li E, Ray PN, Pomès R, Moraes TJ, Gonska T, Ratjen F, Bear CE. Orkambi® and amplifier co-therapy improves function from a rare CFTR mutation in gene-edited cells and patient tissue. EMBO Mol Med 2018; 9:1224-1243. [PMID: 28667089 PMCID: PMC5582412 DOI: 10.15252/emmm.201607137] [Citation(s) in RCA: 83] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The combination therapy of lumacaftor and ivacaftor (Orkambi®) is approved for patients bearing the major cystic fibrosis (CF) mutation: ΔF508. It has been predicted that Orkambi® could treat patients with rarer mutations of similar “theratype”; however, a standardized approach confirming efficacy in these cohorts has not been reported. Here, we demonstrate that patients bearing the rare mutation: c.3700 A>G, causing protein misprocessing and altered channel function—similar to ΔF508‐CFTR, are unlikely to yield a robust Orkambi® response. While in silico and biochemical studies confirmed that this mutation could be corrected and potentiated by lumacaftor and ivacaftor, respectively, this combination led to a minor in vitro response in patient‐derived tissue. A CRISPR/Cas9‐edited bronchial epithelial cell line bearing this mutation enabled studies showing that an “amplifier” compound, effective in increasing the levels of immature CFTR protein, augmented the Orkambi® response. Importantly, this “amplifier” effect was recapitulated in patient‐derived nasal cultures—providing the first evidence for its efficacy in augmenting Orkambi® in tissues harboring a rare CF‐causing mutation. We propose that this multi‐disciplinary approach, including creation of CRISPR/Cas9‐edited cells to profile modulators together with validation using primary tissue, will facilitate therapy development for patients with rare CF mutations.
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Affiliation(s)
- Steven V Molinski
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada.,Programme in Molecular Medicine, Research Institute, Hospital for Sick Children, Toronto, ON, Canada
| | - Saumel Ahmadi
- Programme in Molecular Medicine, Research Institute, Hospital for Sick Children, Toronto, ON, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Wan Ip
- Programme in Translational Medicine, Research Institute, Hospital for Sick Children, Toronto, ON, Canada
| | - Hong Ouyang
- Programme in Translational Medicine, Research Institute, Hospital for Sick Children, Toronto, ON, Canada
| | | | | | - Po-Shun Lee
- Proteostasis Therapeutics, Cambridge, MA, USA
| | - Kethika Kulleperuma
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada.,Programme in Molecular Medicine, Research Institute, Hospital for Sick Children, Toronto, ON, Canada
| | - Kai Du
- Programme in Molecular Medicine, Research Institute, Hospital for Sick Children, Toronto, ON, Canada
| | - Michelle Di Paola
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada.,Programme in Molecular Medicine, Research Institute, Hospital for Sick Children, Toronto, ON, Canada
| | - Paul Dw Eckford
- Programme in Molecular Medicine, Research Institute, Hospital for Sick Children, Toronto, ON, Canada
| | - Onofrio Laselva
- Programme in Molecular Medicine, Research Institute, Hospital for Sick Children, Toronto, ON, Canada
| | - Ling Jun Huan
- Programme in Molecular Medicine, Research Institute, Hospital for Sick Children, Toronto, ON, Canada
| | - Leigh Wellhauser
- Programme in Molecular Medicine, Research Institute, Hospital for Sick Children, Toronto, ON, Canada
| | - Ellen Li
- Programme in Molecular Medicine, Research Institute, Hospital for Sick Children, Toronto, ON, Canada
| | - Peter N Ray
- Division of Molecular Genetics, Hospital for Sick Children, Toronto, ON, Canada
| | - Régis Pomès
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada.,Programme in Molecular Medicine, Research Institute, Hospital for Sick Children, Toronto, ON, Canada
| | - Theo J Moraes
- Programme in Translational Medicine, Research Institute, Hospital for Sick Children, Toronto, ON, Canada.,Department of Paediatrics, University of Toronto, Toronto, ON, Canada
| | - Tanja Gonska
- Programme in Translational Medicine, Research Institute, Hospital for Sick Children, Toronto, ON, Canada.,Department of Paediatrics, University of Toronto, Toronto, ON, Canada
| | - Felix Ratjen
- Division of Respiratory Medicine, Hospital for Sick Children, Toronto, ON, Canada
| | - Christine E Bear
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada .,Programme in Molecular Medicine, Research Institute, Hospital for Sick Children, Toronto, ON, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada
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104
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Rottgen TS, Nickerson AJ, Rajendran VM. Calcium-Activated Cl - Channel: Insights on the Molecular Identity in Epithelial Tissues. Int J Mol Sci 2018; 19:E1432. [PMID: 29748496 PMCID: PMC5983713 DOI: 10.3390/ijms19051432] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 05/07/2018] [Accepted: 05/08/2018] [Indexed: 12/25/2022] Open
Abstract
Calcium-activated chloride secretion in epithelial tissues has been described for many years. However, the molecular identity of the channel responsible for the Ca2+-activated Cl− secretion in epithelial tissues has remained a mystery. More recently, TMEM16A has been identified as a new putative Ca2+-activated Cl− channel (CaCC). The primary goal of this article will be to review the characterization of TMEM16A, as it relates to the physical structure of the channel, as well as important residues that confer voltage and Ca2+-sensitivity of the channel. This review will also discuss the role of TMEM16A in epithelial physiology and potential associated-pathophysiology. This will include discussion of developed knockout models that have provided much needed insight on the functional localization of TMEM16A in several epithelial tissues. Finally, this review will examine the implications of the identification of TMEM16A as it pertains to potential novel therapies in several pathologies.
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Affiliation(s)
- Trey S Rottgen
- Department of Physiology, Pharmacology, and Neuroscience, West Virginia University School of Medicine, Morgantown, WV 26506, USA.
- Department of Biochemistry and Molecular Pharmacology, West Virginia University School of Medicine, Morgantown, WV 26506, USA.
| | - Andrew J Nickerson
- Department of Physiology, Pharmacology, and Neuroscience, West Virginia University School of Medicine, Morgantown, WV 26506, USA.
- Department of Biochemistry and Molecular Pharmacology, West Virginia University School of Medicine, Morgantown, WV 26506, USA.
| | - Vazhaikkurichi M Rajendran
- Department of Physiology, Pharmacology, and Neuroscience, West Virginia University School of Medicine, Morgantown, WV 26506, USA.
- Department of Biochemistry and Molecular Pharmacology, West Virginia University School of Medicine, Morgantown, WV 26506, USA.
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105
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Rahmati N, Hoebeek FE, Peter S, De Zeeuw CI. Chloride Homeostasis in Neurons With Special Emphasis on the Olivocerebellar System: Differential Roles for Transporters and Channels. Front Cell Neurosci 2018; 12:101. [PMID: 29765304 PMCID: PMC5938380 DOI: 10.3389/fncel.2018.00101] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 03/28/2018] [Indexed: 12/14/2022] Open
Abstract
The intraneuronal ionic composition is an important determinant of brain functioning. There is growing evidence that aberrant homeostasis of the intracellular concentration of Cl- ([Cl-]i) evokes, in addition to that of Na+ and Ca2+, robust impairments of neuronal excitability and neurotransmission and thereby neurological conditions. More specifically, understanding the mechanisms underlying regulation of [Cl-]i is crucial for deciphering the variability in GABAergic and glycinergic signaling of neurons, in both health and disease. The homeostatic level of [Cl-]i is determined by various regulatory mechanisms, including those mediated by plasma membrane Cl- channels and transporters. This review focuses on the latest advances in identification, regulation and characterization of Cl- channels and transporters that modulate neuronal excitability and cell volume. By putting special emphasis on neurons of the olivocerebellar system, we establish that Cl- channels and transporters play an indispensable role in determining their [Cl-]i and thereby their function in sensorimotor coordination.
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Affiliation(s)
- Negah Rahmati
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, Netherlands
| | - Freek E. Hoebeek
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, Netherlands
- NIDOD Institute, Wilhelmina Children's Hospital, University Medical Center Utrecht and Brain Center Rudolf Magnus, Utrecht, Netherlands
| | - Saša Peter
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, Netherlands
| | - Chris I. De Zeeuw
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, Netherlands
- Netherlands Institute for Neuroscience, Royal Dutch Academy for Arts and Sciences, Amsterdam, Netherlands
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106
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Jensen AB, Joergensen HB, Dam VS, Kamaev D, Boedtkjer D, Füchtbauer EM, Aalkjaer C, Matchkov VV. Variable Contribution of TMEM16A to Tone in Murine Arterial Vasculature. Basic Clin Pharmacol Toxicol 2018; 123:30-41. [DOI: 10.1111/bcpt.12984] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 01/31/2018] [Indexed: 01/02/2023]
Affiliation(s)
| | | | | | - Dmitrii Kamaev
- Department of Biomedicine; Aarhus University; Aarhus Denmark
| | - Donna Boedtkjer
- Department of Biomedicine; Aarhus University; Aarhus Denmark
- Department of Clinical Medicine; Aarhus University; Aarhus Denmark
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107
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Danielsson J, Vink J, Hyuga S, Fu XW, Funayama H, Wapner R, Blanks AM, Gallos G. Anoctamin Channels in Human Myometrium: A Novel Target for Tocolysis. Reprod Sci 2018; 25:1589-1600. [PMID: 29471754 DOI: 10.1177/1933719118757683] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
BACKGROUND Spontaneous preterm labor leading to preterm birth is a significant obstetric problem leading to neonatal morbidity and mortality. Current tocolytics are not completely effective and novel targets may afford a therapeutic benefit. OBJECTIVE To determine whether the anoctamin (ANO) family, including the calcium-activated chloride channel ANO1, is present in pregnant human uterine smooth muscle (USM) and whether pharmacological and genetic modulation of ANO1 modulates USM contraction. METHODS Reverse transcription-polymerase chain reaction (RT-PCR), quantitative RT-PCR, and immunohistochemical staining were done to determine which members of the ANO family are expressed in human USM. Uterine smooth muscle strips were studied in an organ bath to determine whether ANO1 antagonists inhibit oxytocin-induced USM contractions. Anoctamin 1 small interfering RNA (siRNA) knockdown was performed to determine its effect on filamentous-/globular (F/G)-actin ratio, a measurement of actin polymerization's role in promoting smooth muscle contraction. RESULTS Messenger RNA (mRNA) encoding all members of the ANO family (except ANO7) are expressed in pregnant USM tissue. Anoctamin 1 mRNA expression was decreased 15.2-fold in pregnant USM compared to nonpregnant. Anoctamin 1 protein is expressed in pregnant human USM tissue. Functional organ bath studies with pregnant human USM tissue demonstrated that the ANO1 antagonist benzbromarone attenuates the force and frequency of oxytocin-induced contractions. In human USM cells, siRNA knockdown of ANO1 decreases F-/G-actin ratios. CONCLUSION Multiple members of the ANO family, including the calcium-activated chloride channel ANO1, are expressed in human USM. Antagonism of ANO1 by pharmacological inhibition and genetic knockdown leads to an attenuation of contraction in pregnant human USM. Anoctamin 1 is a potentially novel target for tocolysis.
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Affiliation(s)
- Jennifer Danielsson
- 1 Department of Anesthesiology, Columbia University Medical Center, Columbia University College of Physicians and Surgeons, New York, NY, USA
| | - Joy Vink
- 2 Department of Obstetrics and Gynecology, Columbia University Medical Center, Columbia University College of Physicians and Surgeons, New York, NY, USA
| | - Shunsuke Hyuga
- 1 Department of Anesthesiology, Columbia University Medical Center, Columbia University College of Physicians and Surgeons, New York, NY, USA
| | - Xiao Wen Fu
- 1 Department of Anesthesiology, Columbia University Medical Center, Columbia University College of Physicians and Surgeons, New York, NY, USA
| | - Hiromi Funayama
- 3 Department of Pediatric Dentistry, Tsurumi University School of Dental Medicine, Yokohama, Japan
| | - Ronald Wapner
- 2 Department of Obstetrics and Gynecology, Columbia University Medical Center, Columbia University College of Physicians and Surgeons, New York, NY, USA
| | - Andrew M Blanks
- 4 Cell and Developmental Biology, Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, United Kingdom
| | - George Gallos
- 1 Department of Anesthesiology, Columbia University Medical Center, Columbia University College of Physicians and Surgeons, New York, NY, USA
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108
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Peters CJ, Gilchrist JM, Tien J, Bethel NP, Qi L, Chen T, Wang L, Jan YN, Grabe M, Jan LY. The Sixth Transmembrane Segment Is a Major Gating Component of the TMEM16A Calcium-Activated Chloride Channel. Neuron 2018; 97:1063-1077.e4. [PMID: 29478917 DOI: 10.1016/j.neuron.2018.01.048] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2017] [Revised: 12/03/2017] [Accepted: 01/26/2018] [Indexed: 11/29/2022]
Abstract
Calcium-activated chloride channels (CaCCs) formed by TMEM16A or TMEM16B are broadly expressed in the nervous system, smooth muscles, exocrine glands, and other tissues. With two calcium-binding sites and a pore within each monomer, the dimeric CaCC exhibits voltage-dependent calcium sensitivity. Channel activity also depends on the identity of permeant anions. To understand how CaCC regulates neuronal signaling and how CaCC is, in turn, modulated by neuronal activity, we examined the molecular basis of CaCC gating. Here, we report that voltage modulation of TMEM16A-CaCC involves voltage-dependent occupancy of calcium- and anion-binding site(s) within the membrane electric field as well as a voltage-dependent conformational change intrinsic to the channel protein. These gating modalities all critically depend on the sixth transmembrane segment.
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Affiliation(s)
- Christian J Peters
- Departments of Physiology, Biophysics and Biochemistry, University of California, San Francisco, San Francisco, CA 94158, USA.
| | - John M Gilchrist
- Departments of Physiology, Biophysics and Biochemistry, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Jason Tien
- Departments of Physiology, Biophysics and Biochemistry, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Neville P Bethel
- Department of Pharmaceutical Chemistry and Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Lijun Qi
- Departments of Physiology, Biophysics and Biochemistry, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Tingxu Chen
- Departments of Physiology, Biophysics and Biochemistry, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Lynn Wang
- Departments of Physiology, Biophysics and Biochemistry, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Yuh Nung Jan
- Departments of Physiology, Biophysics and Biochemistry, University of California, San Francisco, San Francisco, CA 94158, USA; Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Michael Grabe
- Department of Pharmaceutical Chemistry and Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Lily Y Jan
- Departments of Physiology, Biophysics and Biochemistry, University of California, San Francisco, San Francisco, CA 94158, USA; Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158, USA.
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109
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Guan L, Song Y, Gao J, Gao J, Wang K. Inhibition of calcium-activated chloride channel ANO1 suppresses proliferation and induces apoptosis of epithelium originated cancer cells. Oncotarget 2018; 7:78619-78630. [PMID: 27732935 PMCID: PMC5346664 DOI: 10.18632/oncotarget.12524] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Accepted: 10/01/2016] [Indexed: 11/25/2022] Open
Abstract
ANO1, a calcium-activated chloride channel, has been reported to be amplified or overexpressed in tissues of several cancers. However, reports on its roles in tumor progression obtained from cancer cell lines are inconsistent, suggesting that the role of ANO1 in tumorigenesis is likely dependent on either its expression level or cell-type expressing ANO1. To investigate the biological roles of ANO1 in different tumor cells, we, in this study, selected several cancer cell lines and a normal HaCaT cell line with high expression levels of ANO1, and examined the function of ANO1 in these cells using approaches of lentiviral knockdown and pharmacological inhibition. We found that ANO1 knockdown significantly inhibited cell proliferation and induced cell apoptosis in either tumor cell lines or normal HaCaT cell line. Moreover, silencing ANO1 arrested cancer cells at G1 phase of cell cycle. Treatment with ANO1 inhibitor CaCCinh-A01 reduced cell viability in a dose-dependent manner. Furthermore, both ANO1 inhibitors CaCCinh-A01 and T16Ainh-A01 significantly suppressed cell migration. Our findings show that ANO1 overexpression promotes cancer cell proliferation and migration; and genetic or pharmacological inhibition of ANO1 induces apoptosis and cell cycle arrest at G1 phase in different types of epithelium-originated cancer cells.
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Affiliation(s)
- Lizhao Guan
- Department of Molecular and Cellular Pharmacology, State Key Laboratory of Natural and Biomimetic Drugs, Peking University School of Pharmaceutical Sciences, Beijing 100191, China
| | - Yan Song
- Department of Molecular and Cellular Pharmacology, State Key Laboratory of Natural and Biomimetic Drugs, Peking University School of Pharmaceutical Sciences, Beijing 100191, China
| | - Jian Gao
- Department of Molecular and Cellular Pharmacology, State Key Laboratory of Natural and Biomimetic Drugs, Peking University School of Pharmaceutical Sciences, Beijing 100191, China
| | - Jianjun Gao
- Department of Pharmacology, Qingdao University School of Pharmacy, Qingdao 266021, China
| | - KeWei Wang
- Department of Molecular and Cellular Pharmacology, State Key Laboratory of Natural and Biomimetic Drugs, Peking University School of Pharmaceutical Sciences, Beijing 100191, China.,Department of Pharmacology, Qingdao University School of Pharmacy, Qingdao 266021, China
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110
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Lin MJ, Yu BP. Colonic Hypermotility in a Rat Model of Irritable Bowel Syndrome Is Associated with Upregulation of TMEM16A in Myenteric Plexus. Dig Dis Sci 2018; 63:3329-3338. [PMID: 30155840 PMCID: PMC6244964 DOI: 10.1007/s10620-018-5261-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 08/20/2018] [Indexed: 12/18/2022]
Abstract
BACKGROUND Irritable bowel syndrome (IBS) is a common disease with intestinal dysmotility, whose mechanism remains elusive. TMEM16A is a calcium-activated chloride channel (CaCC) involved in intestinal slow-wave generation. AIMS To investigate whether TMEM16A is involved in colonic dysmotility in IBS. METHODS A rat model of IBS was established by chronic water avoidance stress (WAS). Colonic pathological alterations were evaluated histologically, and intestinal motility was assessed by intestinal transit time (ITT) and fecal water content (FWC). Visceral sensitivity was determined by visceromotor response (VMR) to colorectal distension (CRD). TMEM16A expression was evaluated by RT-PCR, Western blot, and immunofluorescence. Colonic muscle strip contractility was measured by isometric transducers, and the effect of niflumic acid (NFA), a CaCC antagonist, on colonic motility was examined. RESULTS After 10 days of WAS exposure, ITT was decreased and FWC was elevated. Furthermore, VMR magnitude of WAS rats in response to CRD was significantly enhanced. Protein and mRNA levels of TMEM16A in colon were considerably increased after WAS. The percentage of TMEM16A-positive neurons in myenteric plexus (MP) of WAS rats was significantly higher than controls. Pharmacological blockade of TMEM16A activity by NFA considerably enhanced ITT, with concentration-dependent declines in FWC and VMR magnitude in NFA-treated rats. Further, spontaneous contraction of colonic strips of NFA-treated rats was significantly ameliorated in a concentration-dependent manner in vitro. CONCLUSIONS Upregulation of TMEM16A in MP neurons may play an important role in chronic stress-induced colonic hypermotility, making CaCC-blocking drugs a putatively effective treatment method for colonic hypermotility in IBS.
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Affiliation(s)
- Meng-juan Lin
- Department of Gastroenterology, Renmin Hospital of Wuhan University, No. 238 Jiefang Rd, Wuhan, 430060 Hubei People’s Republic of China
- Key Laboratory of Hubei Province for Digestive System Diseases, Wuhan, People’s Republic of China
| | - Bao-ping Yu
- Department of Gastroenterology, Renmin Hospital of Wuhan University, No. 238 Jiefang Rd, Wuhan, 430060 Hubei People’s Republic of China
- Key Laboratory of Hubei Province for Digestive System Diseases, Wuhan, People’s Republic of China
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111
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He M, Ye W, Wang WJ, Sison ES, Jan YN, Jan LY. Cytoplasmic Cl - couples membrane remodeling to epithelial morphogenesis. Proc Natl Acad Sci U S A 2017; 114:E11161-E11169. [PMID: 29229864 PMCID: PMC5748203 DOI: 10.1073/pnas.1714448115] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Chloride is the major free anion in the extracellular space (>100 mM) and within the cytoplasm in eukaryotes (10 ∼ 20 mM). Cytoplasmic Cl- level is dynamically regulated by Cl- channels and transporters. It is well established that movement of Cl- across the cell membrane is coupled with cell excitability through changes in membrane potential and with water secretion. However, whether cytoplasmic Cl- plays additional roles in animal development and tissue homeostasis is unknown. Here we use genetics, cell biological and pharmacological tools to demonstrate that TMEM16A, an evolutionarily conserved calcium-activated chloride channel (CaCC), regulates cytoplasmic Cl- homeostasis and promotes plasma membrane remodeling required for mammalian epithelial morphogenesis. We demonstrate that TMEM16A-mediated control of cytoplasmic Cl- regulates the organization of the major phosphoinositide species PtdIns(4,5)P2 into microdomains on the plasma membrane, analogous to processes that cluster soluble and membrane proteins into phase-separated droplets. We further show that an adequate cytoplasmic Cl- level is required for proper endocytic trafficking and membrane supply during early stages of ciliogenesis and adherens junction remodeling. Our study thus uncovers a critical function of CaCC-mediated cytoplasmic Cl- homeostasis in controlling the organization of PtdIns(4,5)P2 microdomains and membrane remodeling. This newly defined role of cytoplasmic Cl- may shed light on the mechanisms of intracellular Cl- signaling events crucial for regulating tissue architecture and organelle biogenesis during animal development.
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Affiliation(s)
- Mu He
- Department of Physiology, University of California, San Francisco, CA 94158
| | - Wenlei Ye
- Department of Physiology, University of California, San Francisco, CA 94158
| | - Won-Jing Wang
- Institute of Biochemistry and Molecular Biology, College of Life Sciences, National Yang-Ming University, Taipei, 11221, Taiwan
| | - Eirish S Sison
- Department of Physiology, University of California, San Francisco, CA 94158
- Howard Hughes Medical Institute, University of California, San Francisco, CA 94158
| | - Yuh Nung Jan
- Department of Physiology, University of California, San Francisco, CA 94158
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94158
- Howard Hughes Medical Institute, University of California, San Francisco, CA 94158
| | - Lily Yeh Jan
- Department of Physiology, University of California, San Francisco, CA 94158;
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94158
- Howard Hughes Medical Institute, University of California, San Francisco, CA 94158
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112
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Activation mechanism of the calcium-activated chloride channel TMEM16A revealed by cryo-EM. Nature 2017; 552:421-425. [PMID: 29236691 DOI: 10.1038/nature24652] [Citation(s) in RCA: 198] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Accepted: 10/18/2017] [Indexed: 12/21/2022]
Abstract
The calcium-activated chloride channel TMEM16A is a ligand-gated anion channel that opens in response to an increase in intracellular Ca2+ concentration. The protein is broadly expressed and contributes to diverse physiological processes, including transepithelial chloride transport and the control of electrical signalling in smooth muscles and certain neurons. As a member of the TMEM16 (or anoctamin) family of membrane proteins, TMEM16A is closely related to paralogues that function as scramblases, which facilitate the bidirectional movement of lipids across membranes. The unusual functional diversity of the TMEM16 family and the relationship between two seemingly incompatible transport mechanisms has been the focus of recent investigations. Previous breakthroughs were obtained from the X-ray structure of the lipid scramblase of the fungus Nectria haematococca (nhTMEM16), and from the cryo-electron microscopy structure of mouse TMEM16A at 6.6 Å (ref. 14). Although the latter structure disclosed the architectural differences that distinguish ion channels from lipid scramblases, its low resolution did not permit a detailed molecular description of the protein or provide any insight into its activation by Ca2+. Here we describe the structures of mouse TMEM16A at high resolution in the presence and absence of Ca2+. These structures reveal the differences between ligand-bound and ligand-free states of a calcium-activated chloride channel, and when combined with functional experiments suggest a mechanism for gating. During activation, the binding of Ca2+ to a site located within the transmembrane domain, in the vicinity of the pore, alters the electrostatic properties of the ion conduction path and triggers a conformational rearrangement of an α-helix that comes into physical contact with the bound ligand, and thereby directly couples ligand binding and pore opening. Our study describes a process that is unique among channel proteins, but one that is presumably general for both functional branches of the TMEM16 family.
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Bae JS, Park JY, Park SH, Ha SH, An AR, Noh SJ, Kwon KS, Jung SH, Park HS, Kang MJ, Jang KY. Expression of ANO1/DOG1 is associated with shorter survival and progression of breast carcinomas. Oncotarget 2017; 9:607-621. [PMID: 29416639 PMCID: PMC5787493 DOI: 10.18632/oncotarget.23078] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 11/14/2017] [Indexed: 01/04/2023] Open
Abstract
The expression of ANO1 is considered to have diagnostic specificity for gastrointestinal stromal tumors. However, its function as a calcium-activated chloride channel suggests that the expression of ANO1 is not restricted to gastrointestinal stromal tumors. Recently, it has been reported that ANO1 has roles in the progression of human malignant tumors. However, the role of ANO1 in breast carcinoma has been controversial. Therefore, we investigated the expression of ANO1 in 139 breast carcinoma patients and the role of ANO1 in vitro. The immunohistochemical expression of ANO1 was significantly associated with the expression of β-catenin, cyclin D1, MMP9, snail, and E-cadherin. Especially, ANO1 expression was an independent indicator of poor prognosis of shorter overall survival and relapse-free survival of breast carcinoma patients by multivariate analysis. In MCF7 and MDA-MB-231 breast carcinoma cells, inhibition of ANO1 with T16Ainh-A01 or siRNA for ANO1 significantly suppressed the proliferation of cells. Knock-down of ANO1 with siRNA induced G0/G1 cell cycle arrest and significantly inhibited the invasiveness of breast carcinoma cells. Knock-down of ANO1 decreased the expression of β-catenin, cyclin D1, MMP9, snail, and N-cadherin, and increased the expression of E-cadherin. In conclusion, this study demonstrates that ANO1 expression is an indicator of poor prognosis of breast carcinoma patients and suggests that ANO1 might be a therapeutic target for breast carcinoma patients with ANO1-positive tumors and poor prognosis.
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Affiliation(s)
- Jun Sang Bae
- Department of Pathology, Chonbuk National University Medical School, Research Institute of Clinical Medicine of Chonbuk National University-Biomedical Research Institute of Chonbuk National University Hospital and Research Institute for Endocrine Sciences, Jeonju, Republic of Korea
| | - Jeong Yeol Park
- Department of Forensic Medicine, Chonbuk National University Medical School, Research Institute of Clinical Medicine of Chonbuk National University-Biomedical Research Institute of Chonbuk National University Hospital and Research Institute for Endocrine Sciences, Jeonju, Republic of Korea
| | - See-Hyoung Park
- Department of Bio and Chemical Engineering, Hongik University, Sejong, Republic of Korea
| | - Sang Hoon Ha
- Division of Biotechnology, Chonbuk National University, Iksan, Republic of Korea
| | - Ae Ri An
- Department of Pathology, Chonbuk National University Medical School, Research Institute of Clinical Medicine of Chonbuk National University-Biomedical Research Institute of Chonbuk National University Hospital and Research Institute for Endocrine Sciences, Jeonju, Republic of Korea
| | - Sang Jae Noh
- Department of Forensic Medicine, Chonbuk National University Medical School, Research Institute of Clinical Medicine of Chonbuk National University-Biomedical Research Institute of Chonbuk National University Hospital and Research Institute for Endocrine Sciences, Jeonju, Republic of Korea
| | - Keun Sang Kwon
- Department of Preventive Medicine, Chonbuk National University Medical School, Jeonju, Republic of Korea
| | - Sung Hoo Jung
- Department of Surgery, Chonbuk National University Medical School, Jeonju, Republic of Korea
| | - Ho Sung Park
- Department of Pathology, Chonbuk National University Medical School, Research Institute of Clinical Medicine of Chonbuk National University-Biomedical Research Institute of Chonbuk National University Hospital and Research Institute for Endocrine Sciences, Jeonju, Republic of Korea
| | - Myoung Jae Kang
- Department of Pathology, Chonbuk National University Medical School, Research Institute of Clinical Medicine of Chonbuk National University-Biomedical Research Institute of Chonbuk National University Hospital and Research Institute for Endocrine Sciences, Jeonju, Republic of Korea
| | - Kyu Yun Jang
- Department of Pathology, Chonbuk National University Medical School, Research Institute of Clinical Medicine of Chonbuk National University-Biomedical Research Institute of Chonbuk National University Hospital and Research Institute for Endocrine Sciences, Jeonju, Republic of Korea
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114
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Gao DY, Zhang BL, Leung MCT, Au SCL, Wong PYD, Shum WWC. Coupling of TRPV6 and TMEM16A in epithelial principal cells of the rat epididymis. J Gen Physiol 2017; 148:161-82. [PMID: 27481714 PMCID: PMC4969799 DOI: 10.1085/jgp.201611626] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2016] [Accepted: 07/13/2016] [Indexed: 01/31/2023] Open
Abstract
Principal cells regulate the ionic environment of the epididymal lumen via unknown mechanisms. Gao et al. use electrophysiological and pharmacological tools to characterize rat principal cells and reveal a TRPV6-mediated calcium conductance and TMEM16A-mediated calcium-activated chloride conductance. The epididymis establishes a congenial environment for sperm maturation and protection. Its fluid is acidic, and the calcium concentration is low and declines along the length of the epididymal tubule. However, our knowledge of ionic currents and mechanisms of calcium homeostasis in rat epididymal epithelial cells remains enigmatic. In this study, to better understand calcium regulation in the epididymis, we use the patch-clamp method to record from single rat cauda epididymal principal cells. We detect a constitutively active Ca2+ current with characteristics that match the epithelial calcium channel TRPV6. Electrophysiological and pharmacological data also reveal a constitutively active calcium-activated chloride conductance (CaCC). Removal of extracellular calcium attenuates not only the TRPV6-like conductance, but also the CaCC. Lanthanide block is time dependent such that the TRPV6-like component is inhibited first, followed by the CaCC. The putative CaCC blocker niflumic acid partially inhibits whole-cell currents, whereas La3+ almost abolishes whole-cell currents in principal cells. Membrane potential measurements reveal an interplay between La3+-sensitive ion channels and those that are sensitive to the specific TMEM16A inhibitor tannic acid. In vivo perfusion of the cauda epididymal tubule shows a substantial rate of Ca2+ reabsorption from the luminal side, which is dose-dependently suppressed by ruthenium red, a putative blocker of epithelial Ca2+ channels and CaCC. Finally, we discover messenger RNA for both TRPV6 and TMEM16A in the rat epididymis and show that their proteins colocalize in the apical membrane of principal cells. Collectively, these data provide evidence for a coupling mechanism between TRPV6 and TMEM16A in principal cells that may play an important role in the regulation of calcium homeostasis in the epididymis.
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Affiliation(s)
- Da Yuan Gao
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Bao Li Zhang
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Matthew C T Leung
- School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Simon C L Au
- School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Patrick Y D Wong
- School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Winnie W C Shum
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
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115
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Wang L, Wang K. Highlights for the 6th International Ion Channel Conference: ion channel structure, function, disease and therapeutics. Acta Pharm Sin B 2017; 7:665-669. [PMID: 29159026 PMCID: PMC5687311 DOI: 10.1016/j.apsb.2017.09.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 08/15/2017] [Indexed: 11/17/2022] Open
Abstract
To foster communication and interactions amongst international scholars and scientists in the field of ion channel research, the 6th International Ion Channel Conference (IICC-2017) was held between June 23–27, 2017 in the eastern coastal city of Qingdao, China. The meeting consisted of 450 attendees and 130 speakers and poster presenters. The program consisted of research progress, new findings and ongoing studies that were focused on (1) Ion channel structure and function; (2) Ion channel physiology and human diseases; (3) Ion channels as targets for drug discovery; (4) Technological advances in ion channel research. An insightful overview was presented on the structure and function of the mechanotransduction channel Drosophila NOMPC (No mechanoreceptor potential C), a member of the transient receptor potential (TRP) channel family. Recent studies on Transmembrane protein 16 or Anoctamin-1 (TMEM16A, a member of the calcium-activated chloride channel [CaCC] family) were summarized as well. In addition, topics for ion channel regulation, homeostatic feedback and brain disorders were thoroughly discussed. The presentations at the IICC-2017 offer new insights into our understanding of ion channel structures and functions, and ion channels as targets for drug discovery.
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Zhang Y, Zhang Z, Xiao S, Tien J, Le S, Le T, Jan LY, Yang H. Inferior Olivary TMEM16B Mediates Cerebellar Motor Learning. Neuron 2017; 95:1103-1111.e4. [PMID: 28858616 DOI: 10.1016/j.neuron.2017.08.010] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Revised: 07/17/2017] [Accepted: 08/04/2017] [Indexed: 01/31/2023]
Abstract
Ca2+-activated ion channels shape membrane excitability and Ca2+ dynamics in response to cytoplasmic Ca2+ elevation. Compared to the Ca2+-activated K+ channels, known as BK and SK channels, the physiological importance of Ca2+-activated Cl- channels (CaCCs) in neurons has been largely overlooked. Here we report that CaCCs coexist with BK and SK channels in inferior olivary (IO) neurons that send climbing fibers to innervate cerebellar Purkinje cells for the control of motor learning and timing. Ca2+ influx through the dendritic high-threshold voltage-gated Ca2+ channels activates CaCCs, which contribute to membrane repolarization of IO neurons. Loss of TMEM16B expression resulted in the absence of CaCCs in IO neurons, leading to markedly diminished action potential firing of IO neurons in TMEM16B knockout mice. Moreover, these mutant mice exhibited severe cerebellar motor learning deficits. Our findings thus advance the understanding of the neurophysiology of CaCCs and the ionic basis of IO neuron excitability.
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Affiliation(s)
- Yang Zhang
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
| | - Zhushan Zhang
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
| | - Shaohua Xiao
- Departments of Physiology, Biochemistry and Biophysics, Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Jason Tien
- Departments of Physiology, Biochemistry and Biophysics, Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Son Le
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
| | - Trieu Le
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
| | - Lily Y Jan
- Departments of Physiology, Biochemistry and Biophysics, Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158, USA.
| | - Huanghe Yang
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA; Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA.
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MicroRNA-9 downregulates the ANO1 chloride channel and contributes to cystic fibrosis lung pathology. Nat Commun 2017; 8:710. [PMID: 28955034 PMCID: PMC5617894 DOI: 10.1038/s41467-017-00813-z] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 07/30/2017] [Indexed: 01/06/2023] Open
Abstract
Cystic fibrosis results from reduced cystic fibrosis transmembrane conductance regulator protein activity leading to defective epithelial ion transport. Ca2+-activated Cl− channels mediate physiological functions independently of cystic fibrosis transmembrane conductance regulator. Anoctamin 1 (ANO1/TMEM16A) was identified as the major Ca2+-activated Cl− channel in airway epithelial cells, and we recently demonstrated that downregulation of the anoctamin 1 channel in cystic fibrosis patients contributes to disease severity via an unknown mechanism. Here we show that microRNA-9 (miR-9) contributes to cystic fibrosis and downregulates anoctamin 1 by directly targeting its 3′UTR. We present a potential therapy based on blockage of miR-9 binding to the 3′UTR by using a microRNA target site blocker to increase anoctamin 1 activity and thus compensate for the cystic fibrosis transmembrane conductance regulator deficiency. The target site blocker is tested in in vitro and in mouse models of cystic fibrosis, and could be considered as an alternative strategy to treat cystic fibrosis. Downregulation of the anoctamin 1 calcium channel in airway epithelial cells contributes to pathology in cystic fibrosis. Here the authors show that microRNA-9 targets anoctamin 1 and that inhibiting this interaction improves mucus dynamics in mouse models.
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118
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Wang H, Zou L, Ma K, Yu J, Wu H, Wei M, Xiao Q. Cell-specific mechanisms of TMEM16A Ca 2+-activated chloride channel in cancer. Mol Cancer 2017; 16:152. [PMID: 28893247 PMCID: PMC5594453 DOI: 10.1186/s12943-017-0720-x] [Citation(s) in RCA: 105] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 09/01/2017] [Indexed: 02/08/2023] Open
Abstract
TMEM16A (known as anoctamin 1) Ca2+-activated chloride channel is overexpressed in many tumors. TMEM16A overexpression can be caused by gene amplification in many tumors harboring 11q13 amplification. TMEM16A expression is also controlled in many cancer cells via transcriptional regulation, epigenetic regulation and microRNAs. In addition, TMEM16A activates different signaling pathways in different cancers, e.g. the EGFR and CAMKII signaling in breast cancer, the p38 and ERK1/2 signaling in hepatoma, the Ras-Raf-MEK-ERK1/2 signaling in head and neck squamous cell carcinoma and bladder cancer, and the NFκB signaling in glioma. Furthermore, TMEM16A overexpression has been reported to promote, inhibit, or produce no effects on cell proliferation and migration in different cancer cells. Since TMEM16A exerts different roles in different cancer cells via activation of distinct signaling pathways, we try to develop the idea that TMEM16A regulates cancer cell proliferation and migration in a cell-dependent mechanism. The cell-specific role of TMEM16A may depend on the cellular environment that is predetermined by TMEM16A overexpression mechanisms specific for a particular cancer type. TMEM16A may exert its cell-specific role via its associated protein networks, phosphorylation by different kinases, and involvement of different signaling pathways. In addition, we discuss the role of TMEM16A channel activity in cancer, and its clinical use as a prognostic and predictive marker in different cancers. This review highlights the cell-type specific mechanisms of TMEM16A in cancer, and envisions the promising use of TMEM16A inhibitors as a potential treatment for TMEM16A-overexpressing cancers.
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Affiliation(s)
- Hui Wang
- Department of Ion Channel Pharmacology, School of Pharmacy, China Medical University, No.77 Puhe Road, Shenyang North New Area, Shenyang, 110122 China
| | - Liang Zou
- Department of Anesthesiology, National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100021 China
| | - Ke Ma
- Department of Ion Channel Pharmacology, School of Pharmacy, China Medical University, No.77 Puhe Road, Shenyang North New Area, Shenyang, 110122 China
| | - Jiankun Yu
- Department of Ion Channel Pharmacology, School of Pharmacy, China Medical University, No.77 Puhe Road, Shenyang North New Area, Shenyang, 110122 China
| | - Huizhe Wu
- Department of Pharmacology, School of Pharmacy, China Medical University, Shenyang, 110122 China
| | - Minjie Wei
- Department of Pharmacology, School of Pharmacy, China Medical University, Shenyang, 110122 China
| | - Qinghuan Xiao
- Department of Ion Channel Pharmacology, School of Pharmacy, China Medical University, No.77 Puhe Road, Shenyang North New Area, Shenyang, 110122 China
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119
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Inflammatory mediators mediate airway smooth muscle contraction through a G protein-coupled receptor-transmembrane protein 16A-voltage-dependent Ca 2+ channel axis and contribute to bronchial hyperresponsiveness in asthma. J Allergy Clin Immunol 2017; 141:1259-1268.e11. [PMID: 28754608 DOI: 10.1016/j.jaci.2017.05.053] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Revised: 04/27/2017] [Accepted: 05/19/2017] [Indexed: 11/22/2022]
Abstract
BACKGROUND Allergic inflammation has long been implicated in asthmatic hyperresponsiveness of airway smooth muscle (ASM), but its underlying mechanism remains incompletely understood. Serving as G protein-coupled receptor agonists, several inflammatory mediators can induce membrane depolarization, contract ASM, and augment cholinergic contractile response. We hypothesized that the signal cascade integrating on membrane depolarization by the mediators might involve asthmatic hyperresponsiveness. OBJECTIVE We sought to investigate the signaling transduction of inflammatory mediators in ASM contraction and assess its contribution in the genesis of hyperresponsiveness. METHODS We assessed the capacity of inflammatory mediators to induce depolarization currents by electrophysiological analysis. We analyzed the phenotypes of transmembrane protein 16A (TMEM16A) knockout mice, applied pharmacological reagents, and measured the Ca2+ signal during ASM contraction. To study the role of the depolarization signaling in asthmatic hyperresponsiveness, we measured the synergistic contraction by methacholine and inflammatory mediators both ex vivo and in an ovalbumin-induced mouse model. RESULTS Inflammatory mediators, such as 5-hydroxytryptamin, histamine, U46619, and leukotriene D4, are capable of inducing Ca2+-activated Cl- currents in ASM cells, and these currents are mediated by TMEM16A. A combination of multiple analysis revealed that a G protein-coupled receptor-TMEM16A-voltage-dependent Ca2+ channel signaling axis was required for ASM contraction induced by inflammatory mediators. Block of TMEM16A activity may significantly inhibit the synergistic contraction of acetylcholine and the mediators and hence reduces hypersensitivity. CONCLUSIONS A G protein-coupled receptor-TMEM16A-voltage-dependent Ca2+ channel axis contributes to inflammatory mediator-induced ASM contraction and synergistically activated TMEM16A by allergic inflammatory mediators with cholinergic stimuli.
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120
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Fedigan S, Bradley E, Webb T, Large RJ, Hollywood MA, Thornbury KD, McHale NG, Sergeant GP. Effects of new-generation TMEM16A inhibitors on calcium-activated chloride currents in rabbit urethral interstitial cells of Cajal. Pflugers Arch 2017; 469:1443-1455. [PMID: 28733893 DOI: 10.1007/s00424-017-2028-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 06/21/2017] [Accepted: 07/03/2017] [Indexed: 12/18/2022]
Abstract
Interstitial cells of Cajal (ICC) isolated from the rabbit urethra exhibit Ca2+-activated Cl- currents (I ClCa) that are important for the development of urethral tone. Here, we examined if TMEM16A (ANO1) contributed to this activity by examining the effect of "new-generation" TMEM16A inhibitors, CACCinh-A01 and T16Ainh-A01, on I ClCa recorded from freshly isolated rabbit urethral ICC (RUICC) and on contractions of intact strips of rabbit urethra smooth muscle. Real-time quantitative PCR experiments demonstrated that TMEM16A was highly expressed in rabbit urethra smooth muscle, in comparison to TMEM16B and TMEM16F. Single-cell RT-PCR experiments revealed that only TMEM16A was expressed in freshly isolated RUICC. Depolarization-evoked I ClCa in isolated RUICC, recorded using voltage clamp, were inhibited by CACCinh-A01 and T16Ainh-A01 with IC50 values of 1.2 and 3.4 μM, respectively. Similarly, spontaneous transient inward currents (STICs) recorded from RUICC voltage clamped at -60 mV and spontaneous transient depolarizations (STDs), recorded in current clamp, were also inhibited by CACCinh-A01 and T16Ainh-A01. In contrast, spontaneous Ca2+ waves in isolated RUICC were only partially reduced by CACCinh-A01 and T16Ainh-A01. Finally, neurogenic contractions of strips of rabbit urethra smooth muscle (RUSM), evoked by electric field stimulation (EFS), were also significantly reduced by CACCinh-A01 and T16Ainh-A01. These data are consistent with the idea that TMEM16A is involved with CACCs in RUICC and in contraction of rabbit urethral smooth muscle.
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Affiliation(s)
- Stephen Fedigan
- The Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Co. Louth, Ireland
| | - Eamonn Bradley
- The Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Co. Louth, Ireland
| | - Timothy Webb
- The Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Co. Louth, Ireland
| | - Roddy J Large
- The Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Co. Louth, Ireland
| | - Mark A Hollywood
- The Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Co. Louth, Ireland
| | - Keith D Thornbury
- The Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Co. Louth, Ireland
| | - Noel G McHale
- The Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Co. Louth, Ireland
| | - Gerard P Sergeant
- The Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Co. Louth, Ireland.
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121
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Kamaleddin MA. Molecular, biophysical, and pharmacological properties of calcium-activated chloride channels. J Cell Physiol 2017; 233:787-798. [PMID: 28121009 DOI: 10.1002/jcp.25823] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 01/24/2017] [Indexed: 12/15/2022]
Abstract
Calcium-activated chloride channels (CaCCs) are a family of anionic transmembrane ion channels. They are mainly responsible for the movement of Cl- and other anions across the biological membranes, and they are widely expressed in different tissues. Since the Cl- flow into or out of the cell plays a crucial role in hyperpolarizing or depolarizing the cells, respectively, the impact of intracellular Ca2+ concentration on these channels is attracting a lot of attentions. After summarizing the molecular, biophysical, and pharmacological properties of CaCCs, the role of CaCCs in normal cellular functions will be discussed, and I will emphasize how dysregulation of CaCCs in pathological conditions can account for different diseases. A better understanding of CaCCs and a pivotal regulatory role of Ca2+ can shed more light on the therapeutic strategies for different neurological disorders that arise from chloride dysregulation, such as asthma, cystic fibrosis, and neuropathic pain.
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Affiliation(s)
- Mohammad Amin Kamaleddin
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada.,Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, Ontario, Canada
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Kulkarni S, Bill A, Godse NR, Khan NI, Kass JI, Steehler K, Kemp C, Davis K, Bertrand CA, Vyas AR, Holt DE, Grandis JR, Gaither LA, Duvvuri U. TMEM16A/ANO1 suppression improves response to antibody-mediated targeted therapy of EGFR and HER2/ERBB2. Genes Chromosomes Cancer 2017; 56:460-471. [PMID: 28177558 DOI: 10.1002/gcc.22450] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 02/02/2017] [Accepted: 02/03/2017] [Indexed: 12/22/2022] Open
Abstract
TMEM16A, a Ca2+ -activated Cl- channel, contributes to tumor growth in breast cancer and head and neck squamous cell carcinoma (HNSCC). Here, we investigated whether TMEM16A influences the response to EGFR/HER family-targeting biological therapies. Inhibition of TMEM16A Cl- channel activity in breast cancer cells with HER2 amplification induced a loss of viability. Cells resistant to trastuzumab, a monoclonal antibody targeting HER2, showed an increase in TMEM16A expression and heightened sensitivity to Cl- channel inhibition. Treatment of HNSCC cells with cetuximab, a monoclonal antibody targeting EGFR, and simultaneous TMEM16A suppression led to a pronounced loss of viability. Biochemical analyses of cells subjected to TMEM16A inhibitors or expressing chloride-deficient forms of TMEM16A provide further evidence that TMEM16A channel function may play a role in regulating EGFR/HER2 signaling. These data demonstrate that TMEM16A regulates EGFR and HER2 in growth and survival pathways. Furthermore, in the absence of TMEM16A cotargeting, tumor cells may acquire resistance to EGFR/HER inhibitors. Finally, targeting TMEM16A improves response to biological therapies targeting EGFR/HER family members.
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Affiliation(s)
- Sucheta Kulkarni
- Department of Otolaryngology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania.,Veterans Affairs Pittsburgh Health System, Pittsburgh, Pennsylvania
| | - Anke Bill
- Novartis Institute for Biomedical Research, Cambridge, MA, 02139
| | - Neal R Godse
- Department of Otolaryngology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania
| | - Nayel I Khan
- Department of Otolaryngology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania
| | - Jason I Kass
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Kevin Steehler
- Department of Otolaryngology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania
| | - Carolyn Kemp
- Department of Otolaryngology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania.,Veterans Affairs Pittsburgh Health System, Pittsburgh, Pennsylvania
| | - Kara Davis
- Department of Otolaryngology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania
| | - Carol A Bertrand
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Avani R Vyas
- Department of Otolaryngology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania
| | - Douglas E Holt
- Department of Otolaryngology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania
| | - Jennifer R Grandis
- Department of Otolaryngology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania
| | - L Alex Gaither
- Novartis Institute for Biomedical Research, Cambridge, MA, 02139
| | - Umamaheswar Duvvuri
- Department of Otolaryngology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania.,Veterans Affairs Pittsburgh Health System, Pittsburgh, Pennsylvania
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He Y, Li H, Chen Y, Li P, Gao L, Zheng Y, Sun Y, Chen J, Qian X. Expression of anoctamin 1 is associated with advanced tumor stage in patients with non-small cell lung cancer and predicts recurrence after surgery. Clin Transl Oncol 2017; 19:1091-1098. [DOI: 10.1007/s12094-017-1643-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Accepted: 03/02/2017] [Indexed: 02/07/2023]
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Malysz J, Gibbons SJ, Saravanaperumal SA, Du P, Eisenman ST, Cao C, Oh U, Saur D, Klein S, Ordog T, Farrugia G. Conditional genetic deletion of Ano1 in interstitial cells of Cajal impairs Ca 2+ transients and slow waves in adult mouse small intestine. Am J Physiol Gastrointest Liver Physiol 2017; 312:G228-G245. [PMID: 27979828 PMCID: PMC5401988 DOI: 10.1152/ajpgi.00363.2016] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 12/05/2016] [Accepted: 12/12/2016] [Indexed: 01/31/2023]
Abstract
Myenteric plexus interstitial cells of Cajal (ICC-MY) in the small intestine are Kit+ electrical pacemakers that express the Ano1/TMEM16A Ca2+-activated Cl- channel, whose functions in the gastrointestinal tract remain incompletely understood. In this study, an inducible Cre-LoxP-based approach was used to advance the understanding of Ano1 in ICC-MY of adult mouse small intestine. KitCreERT2/+;Ano1Fl/Fl mice were treated with tamoxifen or vehicle, and small intestines (mucosa free) were examined. Quantitative RT-PCR demonstrated ~50% reduction in Ano1 mRNA in intestines of conditional knockouts (cKOs) compared with vehicle-treated controls. Whole mount immunohistochemistry showed a mosaic/patchy pattern loss of Ano1 protein in ICC networks. Ca2+ transients in ICC-MY network of cKOs displayed reduced duration compared with highly synchronized controls and showed synchronized and desynchronized profiles. When matched, the rank order for Ano1 expression in Ca2+ signal imaged fields of view was as follows: vehicle controls>>>cKO(synchronized)>cKO(desynchronized). Maintenance of Ca2+ transients' synchronicity despite high loss of Ano1 indicates a large functional reserve of Ano1 in the ICC-MY network. Slow waves in cKOs displayed reduced duration and increased inter-slow-wave interval and occurred in regular- and irregular-amplitude oscillating patterns. The latter activity suggested ongoing interaction by independent interacting oscillators. Lack of slow waves and depolarization, previously reported for neonatal constitutive knockouts, were also seen. In summary, Ano1 in adults regulates gastrointestinal function by determining Ca2+ transients and electrical activity depending on the level of Ano1 expression. Partial Ano1 loss results in Ca2+ transients and slow waves displaying reduced duration, while complete and widespread absence of Ano1 in ICC-MY causes lack of slow wave and desynchronized Ca2+ transients.NEW & NOTEWORTHY The Ca2+-activated Cl- channel, Ano1, in interstitial cells of Cajal (ICC) is necessary for normal gastrointestinal motility. We knocked out Ano1 to varying degrees in ICC of adult mice. Partial knockout of Ano1 shortened the widths of electrical slow waves and Ca2+ transients in myenteric ICC but Ca2+ transient synchronicity was preserved. Near-complete knockout was necessary for transient desynchronization and loss of slow waves, indicating a large functional reserve of Ano1 in ICC.
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Affiliation(s)
- John Malysz
- Enteric NeuroScience Program, Mayo Clinic, Rochester, Minnesota
| | - Simon J Gibbons
- Enteric NeuroScience Program, Mayo Clinic, Rochester, Minnesota
| | | | - Peng Du
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Seth T Eisenman
- Enteric NeuroScience Program, Mayo Clinic, Rochester, Minnesota
| | - Chike Cao
- Enteric NeuroScience Program, Mayo Clinic, Rochester, Minnesota
| | - Uhtaek Oh
- Sensory Research Center, CRI, College of Pharmacy, Seoul National University, Seoul, Republic of Korea; and
| | - Dieter Saur
- Department of Internal Medicine II, Klinikum rechts der Isar, Technische Universität München, München, Germany
| | - Sabine Klein
- Department of Internal Medicine II, Klinikum rechts der Isar, Technische Universität München, München, Germany
| | - Tamas Ordog
- Enteric NeuroScience Program, Mayo Clinic, Rochester, Minnesota
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4-isopropylcyclohexanol has potential analgesic effects through the inhibition of anoctamin 1, TRPV1 and TRPA1 channel activities. Sci Rep 2017; 7:43132. [PMID: 28225032 PMCID: PMC5320485 DOI: 10.1038/srep43132] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 01/19/2017] [Indexed: 12/31/2022] Open
Abstract
Interactions between calcium-activated chloride channel anoctamin 1 (ANO1) and transient receptor potential vanilloid 1 (TRPV1) enhance pain sensations in mice, suggesting that ANO1 inhibition could have analgesic effects. Here we show that menthol and the menthol analogue isopropylcyclohexane (iPr-CyH) inhibited ANO1 channels in mice. The iPr-CyH derivative 4-isopropylcyclohexanol (4-iPr-CyH-OH) inhibited mouse ANO1 currents more potently than iPr-CyH. Moreover, 4-iPr-CyH-OH inhibited the activities of TRPV1, TRP ankyrin 1 (TRPA1), TRP melastatin 8 (TRPM8) and TRPV4. Single-channel analysis revealed that 4-iPr-CyH-OH reduced TRPV1 and TRPA1 current open-times without affecting unitary amplitude or closed-time, suggesting that it affected gating rather than blocking the channel pore. The ability of 4-iPr-CyH-OH to inhibit action potential generation and reduce pain-related behaviors induced by capsaicin in mice suggests that 4-iPr-CyH-OH could have analgesic applications. Thus, 4-iPr-CyH-OH is a promising base chemical to develop novel analgesics that target ANO1 and TRP channels.
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126
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Guo S, Chen Y, Pang C, Wang X, Qi J, Mo L, Zhang H, An H, Zhan Y. Ginsenoside Rb1, a novel activator of the TMEM16A chloride channel, augments the contraction of guinea pig ileum. Pflugers Arch 2017; 469:681-692. [PMID: 28124133 DOI: 10.1007/s00424-017-1934-x] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 12/25/2016] [Accepted: 01/02/2017] [Indexed: 01/01/2023]
Abstract
Calcium-activated chloride channels (CaCCs) play important roles in many physiological processes, and the molecular basis of CaCCs has been identified as TMEM16A in many cell types. It is well established that TMEM16A is a drug target in many diseases, including cystic fibrosis, hypertension, asthma, and various tumors. Therefore, identifying potent and specific modulators of the TMEM16A channel is crucial. In this study, we identified the first natural activator of TMEM16A from traditional Chinese medicine and explored its mechanism. Our data showed that Ginsenoside Rb1 (GRb1) can activate TMEM16A directly from the intracellular side in a dose-dependent manner at an EC50 of 38.4 ± 2.14 μM. GRb1 specifically activated TMEM16A/B, but not the other previously proposed CaCC mediators such as CFTR and bestrophin. Moreover, GRb1 promoted proliferation of CHO cells stably expressing TMEM16A, in a concentration-dependent manner. Finally, we showed that GRb1 increased the amplitude and frequency of contractions in an isolated guinea pig ileum assay in vivo. In summary, GRb1 can be considered a lead compound for the development of novel drugs for the treatment of diseases caused by TMEM16A dysfunction.
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Affiliation(s)
- Shuai Guo
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, 300401, China.,School of Electrical Engineering, Hebei University of Technology, Tianjin, 300401, China
| | - Yafei Chen
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, 300401, China
| | - Chunli Pang
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, 300401, China
| | - Xuzhao Wang
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, 300401, China
| | - Jinlong Qi
- Key Laboratory of Neural and Vascular Biology, Ministry of Education, The Key Laboratory of Pharmacology and Toxicology for New Drug, Hebei Province, Department of Pharmacology, Hebei Medical University, Shijiazhuang, 050017, China
| | - Li Mo
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, 300401, China
| | - Hailin Zhang
- Key Laboratory of Neural and Vascular Biology, Ministry of Education, The Key Laboratory of Pharmacology and Toxicology for New Drug, Hebei Province, Department of Pharmacology, Hebei Medical University, Shijiazhuang, 050017, China
| | - Hailong An
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, 300401, China.
| | - Yong Zhan
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, 300401, China.
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Abstract
UNLABELLED Transmembrane protein 16A (TMEM16A) regulates a wide variety of cellular activities, including epithelial fluid secretion and maintenance of ion homeostasis. Lipopolysaccharide (LPS), an outer membrane component of Gram-negative bacteria, is one of the major causes of acute lung injury (ALI). In this study, we investigated the effects of LPS on the expression of TMEM16A in LA795 cells and mouse lung tissue and the potential mechanism. RESULT We detected the expression of TMEM16A in LA795 cells and mouse lung tissue by RT-PCR, Western blot, and RNA interference techniques. TMEM16A expression was significantly increased by LPS stimulation in LA795 cells and in mouse lung tissue. Moreover, the LPS-induced TMEM16A expression enhancement in lung tissue was much more prominent in the alveolar epithelial region than in bigger airway epithelial cells. The typical TMEM16A current was recorded, and LPS treatment significantly enhances the current amplitude in LA795 cells. TMEM16A shRNA or TMEM16A inhibitor (T16Ainh-A01) did not affect alveolar fluid clearance (AFC), while co-application of T16Ainh-A01 induced a stronger AFC inhibition than LPS alone. LPS notably and synchronously enhanced Akt phosphorylation (p-Akt) and TMEM16A expression in a time-dependent manner in LA795 cells. Taken together, our results suggest that TMEM16A maybe plays an important role in pathological conditions of LPS-induced ALI as a protective protein.
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128
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Yu B, Jiang Y, Jin L, Ma T, Yang H. Role of Quercetin in Modulating Chloride Transport in the Intestine. Front Physiol 2016; 7:549. [PMID: 27932986 PMCID: PMC5120089 DOI: 10.3389/fphys.2016.00549] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 11/01/2016] [Indexed: 12/17/2022] Open
Abstract
Epithelial chloride channels provide the pathways for fluid secretion in the intestine. Cystic fibrosis transmembrane conductance regulator (CFTR) and calcium-activated chloride channels (CaCCs) are the main chloride channels in the luminal membrane of enterocytes. These transmembrane proteins play important roles in many physiological processes. In this study, we have identified a flavonoid quercetin as a modulator of CaCC chloride channel activity. Fluorescence quenching assay showed that quercetin activated Cl− transport in a dose-dependent manner, with EC50 ~37 μM. Short-circuit current analysis confirmed that quercetin activated CaCC-mediated Cl− currents in HT-29 cells that can be abolished by CaCCinh-A01. Ex vivo studies indicated that application of quercetin to mouse ileum and colon on serosal side resulted in activation of CFTR and CaCC-mediated Cl− currents. Notably, we found that quercetin exhibited inhibitory effect against ANO1 chloride channel activity in ANO1-expressing FRT cells and decreased mouse intestinal motility. Quercetin-stimulated short-circuit currents in mouse ileum was multi-component, which included elevation of Ca2+ concentration through L-type calcium channel and activation of basolateral NKCC, Na+/K+-ATPase, and K+ channels. In vivo studies further revealed that quercetin promoted fluid secretion in mouse ileum. The modulatory effect of quercetin on CaCC chloirde channels may therefore represent a potential therapeutic strategy for treating CaCC-related diseases like constipation, secretory diarrhea and hypertension. The inverse effects of quercetin on CaCCs provided evidence that ANO1 and intestinal epithelial CaCCs are different calcium-activated chloride channels.
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Affiliation(s)
- Bo Yu
- Liaoning Provincial Key Laboratory of Biotechnology and Drug Discovery, School of Life Sciences, Liaoning Normal University Dalian, China
| | - Yu Jiang
- Liaoning Provincial Key Laboratory of Biotechnology and Drug Discovery, School of Life Sciences, Liaoning Normal University Dalian, China
| | - Lingling Jin
- College of Basic Medical Sciences, Dalian Medical University Dalian, China
| | - Tonghui Ma
- College of Basic Medical Sciences, Dalian Medical University Dalian, China
| | - Hong Yang
- Liaoning Provincial Key Laboratory of Biotechnology and Drug Discovery, School of Life Sciences, Liaoning Normal University Dalian, China
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129
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Kamikawa A, Ichii O, Sakazaki J, Ishikawa T. Ca2+-activated Cl− channel currents in mammary secretory cells from lactating mouse. Am J Physiol Cell Physiol 2016; 311:C808-C819. [DOI: 10.1152/ajpcell.00050.2016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 08/19/2016] [Indexed: 11/22/2022]
Abstract
The Cl− secretion via Ca2+-activated Cl− channel (CaCC) is critical for fluid secretion in exocrine glands like the salivary gland. Also in the mammary gland, it has been hypothesized that CaCC plays an important role in the secretion of Cl− and aqueous phase of milk. However, there has been no evidence for the functional expression of CaCC in native mammary secretory (MS) cells of lactating animals. We therefore assessed membrane current in MS cells that were freshly isolated from lactating mice using whole cell patch-clamp techniques. In MS cells, we detected CaCC current that exhibited the following characteristics: 1) Ca2+-dependent activation at the concentrations of submicromolar range; 2) voltage-dependent activation; 3) slow kinetics for activation and deactivation; 4) outward rectification of the steady-state current; 5) anion permeability in the sequence of I− > NO3− > Br− > Cl− >> glutamate; 6) inhibition by Cl− channel blockers (niflumic acid, DIDS, and CaCCinh-A01). These characteristics of native CaCC current were similar to reported characteristics of heterologously expressed TMEM16A. RT-PCR analyses showed the expression of multiple CaCC channels including TMEM16A, Best1, and Best3 in the mammary glands of lactating mice. Immunohistochemical staining revealed the localization of TMEM16A protein at the apical membrane of the MS cells. Collectively, our data strongly suggest that MS cells functionally express CaCC, which is at least partly constituted by TMEM16A. The CaCC such as TMEM16A at the apical membrane of the MS cells may influence the quantity and/or quality of milk.
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Affiliation(s)
- Akihiro Kamikawa
- Department of Basic Veterinary Medicine, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Japan; and
| | - Osamu Ichii
- Laboratory of Anatomy, Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Junpei Sakazaki
- Department of Basic Veterinary Medicine, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Japan; and
| | - Toru Ishikawa
- Department of Basic Veterinary Medicine, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Japan; and
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130
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Ma K, Wang H, Yu J, Wei M, Xiao Q. New Insights on the Regulation of Ca 2+ -Activated Chloride Channel TMEM16A. J Cell Physiol 2016; 232:707-716. [PMID: 27682822 DOI: 10.1002/jcp.25621] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Accepted: 09/27/2016] [Indexed: 12/16/2022]
Abstract
TMEM16A, also known as anoctamin 1, is a recently identified Ca2+ -activated chloride channel and the first member of a 10-member TMEM16 family. TMEM16A dysfunction is implicated in many diseases such as cancer, hypertension, and cystic fibrosis. TMEM16A channels are well known to be dually regulated by voltage and Ca2+ . In addition, recent studies have revealed that TMEM16A channels are regulated by many molecules such as calmodulin, protons, cholesterol, and phosphoinositides, and a diverse range of stimuli such as thermal and mechanical stimuli. A better understanding of the regulatory mechanisms of TMEM16A is important to understand its physiological and pathological role. Recently, the crystal structure of a TMEM16 family member from the fungus Nectria haematococcaten (nhTMEM16) is discovered, and provides valuable information for studying the structure and function of TMEM16A. In this review, we discuss the structure and function of TMEM16A channels based on the crystal structure of nhTMEM16A and focus on the regulatory mechanisms of TMEM16A channels. J. Cell. Physiol. 232: 707-716, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Ke Ma
- Department of Ion Channel Pharmacology, School of Pharmacy, China Medical University, Shenyang, P. R. China
| | - Hui Wang
- Department of Ion Channel Pharmacology, School of Pharmacy, China Medical University, Shenyang, P. R. China
| | - Jiankun Yu
- Department of Ion Channel Pharmacology, School of Pharmacy, China Medical University, Shenyang, P. R. China
| | - Minjie Wei
- Department of Pharmacology, School of Pharmacy, China Medical University, Shenyang, P. R. China
| | - Qinghuan Xiao
- Department of Ion Channel Pharmacology, School of Pharmacy, China Medical University, Shenyang, P. R. China
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131
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Interleukin-13 stimulates MUC5AC expression via a STAT6-TMEM16A-ERK1/2 pathway in human airway epithelial cells. Int Immunopharmacol 2016; 40:106-114. [PMID: 27588910 DOI: 10.1016/j.intimp.2016.08.033] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 08/12/2016] [Accepted: 08/25/2016] [Indexed: 12/15/2022]
Abstract
Transmembrane protein 16A (TMEM16A), a channel underlying the calcium-activated chloride channel (CaCC) currents, has been shown to be a key regulator of mucus overproduction in airway epithelial cells. However, the precise molecular mechanism involved in the TMEM16A-mediated mucus secretion remains unclear. In the present study, we inquired into a novel signaling mechanism for TMEM16A driving mucin 5AC (MUC5AC) production in human airway epithelial cells. Following treatment for 24-48h with type 13 interleukin (IL-13), an upregulation of TMEM16A expression in both mRNA and protein levels was observed in human bronchial epithelial cell line (HBE16), while signal transducer and activator of transcription 6 (STAT6) inhibition could decrease this elevated expression, suggesting that the regulation of TMEM16A expression by IL-13 was via a STAT6-based transcriptional mechanism. Further investigation of the HBE16 cells revealed that TMEM16A knockdown or specific chloride channel inhibitor T16Ainh-A01 could suppress the CaCC currents and consequently reduce the extracellular regulated kinase (ERK1/2) phosphorylation, accompanying a dramatical decrease in MUC5AC expression. Moreover, pretreated with PD98059, an inhibitor of ERK1/2, the HB16 cells showed a remarkable diminution in TMEM16A-mediated MUC5AC expression. Altogether, STAT6-TMEM16A-ERK1/2 signal pathway and TMEM16A channel activity are required for the IL-13-induced TMEM16A mediated mucus production.
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132
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Jiang Y, Yu B, Yang H, Ma T. Shikonin Inhibits Intestinal Calcium-Activated Chloride Channels and Prevents Rotaviral Diarrhea. Front Pharmacol 2016; 7:270. [PMID: 27601995 PMCID: PMC4993765 DOI: 10.3389/fphar.2016.00270] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 08/10/2016] [Indexed: 01/26/2023] Open
Abstract
Secretory diarrhea remains a global health burden and causes major mortality in children. There have been some focuses on antidiarrheal therapies that may reduce fluid losses and intestinal motility in diarrheal diseases. In the present study, we identified shikonin as an inhibitor of TMEM16A chloride channel activity using cell-based fluorescent-quenching assay. The IC50 value of shikonin was 6.5 μM. Short-circuit current measurements demonstrated that shikonin inhibited Eact-induced Cl(-) current in a dose-dependent manner, with IC50 value of 1.5 μM. Short-circuit current measurement showed that shikonin exhibited inhibitory effect against CCh-induced Cl(-) currents in mouse colonic epithelia but did not affect cytoplasmic Ca(2+) concentration as well as the other major enterocyte chloride channel conductance regulator. Characterization study found that shikonin inhibited basolateral K(+) channel activity without affecting Na(+)/K(+)-ATPase activities. In vivo studies revealed that shikonin significantly delayed intestinal motility in mice and reduced stool water content in a neonatal mice model of rotaviral diarrhea without affecting the viral infection process in vivo. Taken together, the results suggested that shikonin inhibited enterocyte calcium-activated chloride channels, the inhibitory effect was partially through inhbition of basolateral K(+) channel activity, and shikonin could be a lead compound in the treatment of rotaviral secretory diarrhea.
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Affiliation(s)
- Yu Jiang
- Liaoning Provincial Key Laboratory of Biotechnology and Drug Discovery, School of Life Sciences, Liaoning Normal University Dalian, China
| | - Bo Yu
- Liaoning Provincial Key Laboratory of Biotechnology and Drug Discovery, School of Life Sciences, Liaoning Normal University Dalian, China
| | - Hong Yang
- Liaoning Provincial Key Laboratory of Biotechnology and Drug Discovery, School of Life Sciences, Liaoning Normal University Dalian, China
| | - Tonghui Ma
- College of Basic Medical Sciences, Dalian Medical University Dalian, China
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133
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Han Y, Shewan AM, Thorn P. HCO3- Transport through Anoctamin/Transmembrane Protein ANO1/TMEM16A in Pancreatic Acinar Cells Regulates Luminal pH. J Biol Chem 2016; 291:20345-52. [PMID: 27510033 DOI: 10.1074/jbc.m116.750224] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Indexed: 02/01/2023] Open
Abstract
The identification of ANO1/TMEM16A as the likely calcium-dependent chloride channel of exocrine glands has led to a more detailed understanding of its biophysical properties. This includes a calcium-dependent change in channel selectivity and evidence that HCO3 (-) permeability can be significant. Here we use freshly isolated pancreatic acini that preserve the luminal structure to measure intraluminal pH and test the idea that ANO1/TMEM16A contributes to luminal pH balance. Our data show that, under physiologically relevant stimulation with 10 pm cholesystokinin, the luminal acid load that results from the exocytic fusion of zymogen granules is significantly blunted by HCO3 (-) buffer in comparison with HEPES, and that this is blocked by the specific TMEM16A inhibitor T16inh-A01. Furthermore, in a model of acute pancreatitis, we observed substantive luminal acidification and provide evidence that ANO1/TMEM16A acts to attenuate this pH shift. We conclude that ANO1/TMEM16A is a significant pathway in pancreatic acinar cells for HCO3 (-) secretion into the lumen.
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Affiliation(s)
| | - Annette M Shewan
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland 4072, Australia and
| | - Peter Thorn
- From the School of Biomedical Sciences and the Charles Perkins Centre, John Hopkins Drive, University of Sydney, Sydney, New South Wales 2050, Australia
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134
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Pera T, Penn RB. Bronchoprotection and bronchorelaxation in asthma: New targets, and new ways to target the old ones. Pharmacol Ther 2016; 164:82-96. [PMID: 27113408 PMCID: PMC4942340 DOI: 10.1016/j.pharmthera.2016.04.002] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 04/07/2016] [Indexed: 01/01/2023]
Abstract
Despite over 50years of inhaled beta-agonists and corticosteroids as the default management or rescue drugs for asthma, recent research suggests that new therapeutic options are likely to emerge. This belief stems from both an improved understanding of what causes and regulates airway smooth muscle (ASM) contraction, and the identification of new targets whose inhibition or activation can relax ASM. In this review we discuss the recent findings that provide new insight into ASM contractile regulation, a revolution in pharmacology that identifies new ways to "tune" G protein-coupled receptors to improve therapeutic efficacy, and the discovery of several novel targets/approaches capable of effecting bronchoprotection or bronchodilation.
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Affiliation(s)
- Tonio Pera
- Center for Translational Medicine and Jane and Leonard Korman Lung Center, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, United States.
| | - Raymond B Penn
- Center for Translational Medicine and Jane and Leonard Korman Lung Center, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, United States.
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135
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Chaudhury A. Furthering the debate on the role of interstitial cells of Cajal in enteric inhibitory neuromuscular neurotransmission. Am J Physiol Cell Physiol 2016; 311:C479-81. [PMID: 27385720 DOI: 10.1152/ajpcell.00067.2016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 07/05/2016] [Indexed: 12/22/2022]
Abstract
The gut, a muscular organ, performs a critical role in transporting ingested contents, yet it is also controlled to periodically stop transport to maximize digestion and toxin detection. The complex intraluminal composition and rheology challenge the mechanistic requirements of inhibitory neuromuscular neurotransmission. The interstitial cells of Cajal (ICCs)-generated slow wave may tune the promiscuous luminal chemical environment, which prepares the smooth muscle membrane potential for a depolarizing or hyperpolarizing response as needed. Slow waves are abolished during stimulation-induced inhibitory junction potentials (IJPs) due to purinergic-nitrergic tandem neurotransmission. Recent data demonstrating intact IJPs in a genomic knockout of ICCs provide rigorous evidence of the noncontribution of ICCs during evoked neurotransmission. This perspective article discusses the priority areas of investigations in enteric musculomotor transmission, for understanding its near-perfect design for chemical space sensing, as well as diseases in which the luminal transport braking process becomes dysfunctional, leading to delayed gastric emptying or intestinal transit.
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136
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Epithelial Anion Transport as Modulator of Chemokine Signaling. Mediators Inflamm 2016; 2016:7596531. [PMID: 27382190 PMCID: PMC4921137 DOI: 10.1155/2016/7596531] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Revised: 05/03/2016] [Accepted: 05/12/2016] [Indexed: 12/16/2022] Open
Abstract
The pivotal role of epithelial cells is to secrete and absorb ions and water in order to allow the formation of a luminal fluid compartment that is fundamental for the epithelial function as a barrier against environmental factors. Importantly, epithelial cells also take part in the innate immune system. As a first line of defense they detect pathogens and react by secreting and responding to chemokines and cytokines, thus aggravating immune responses or resolving inflammatory states. Loss of epithelial anion transport is well documented in a variety of diseases including cystic fibrosis, chronic obstructive pulmonary disease, asthma, pancreatitis, and cholestatic liver disease. Here we review the effect of aberrant anion secretion with focus on the release of inflammatory mediators by epithelial cells and discuss putative mechanisms linking these transport defects to the augmented epithelial release of chemokines and cytokines. These mechanisms may contribute to the excessive and persistent inflammation in many respiratory and gastrointestinal diseases.
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137
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Lee YS, Lee JK, Bae Y, Lee BS, Kim E, Cho CH, Ryoo K, Yoo J, Kim CH, Yi GS, Lee SG, Lee CJ, Kang SS, Hwang EM, Park JY. Suppression of 14-3-3γ-mediated surface expression of ANO1 inhibits cancer progression of glioblastoma cells. Sci Rep 2016; 6:26413. [PMID: 27212225 PMCID: PMC4876403 DOI: 10.1038/srep26413] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Accepted: 05/03/2016] [Indexed: 01/03/2023] Open
Abstract
Anoctamin-1 (ANO1) acts as a Ca2+-activated Cl− channel in various normal tissues, and its expression is increased in several different types of cancer. Therefore, understanding the regulation of ANO1 surface expression is important for determining its physiological and pathophysiological functions. However, the trafficking mechanism of ANO1 remains elusive. Here, we report that segment a (N-terminal 116 amino acids) of ANO1 is crucial for its surface expression, and we identified 14-3-3γ as a binding partner for anterograde trafficking using yeast two-hybrid screening. The surface expression of ANO1 was enhanced by 14-3-3γ, and the Thr9 residue of ANO1 was critical for its interaction with 14-3-3γ. Gene silencing of 14-3-3γ and/or ANO1 demonstrated that suppression of ANO1 surface expression inhibited migration and invasion of glioblastoma cells. These findings provide novel therapeutic implications for glioblastomas, which are associated with poor prognosis.
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Affiliation(s)
- Young-Sun Lee
- School of Biosystem and Biomedical Science, College of Health Science, Korea University, Seoul 02841, Republic of Korea.,Department of Anatomy and Convergence Medical Science, Institute of Health Sciences, School of Medicine, Gyeongsang National University, Jinju 52727, Republic of Korea.,Center for Functional Connectomics, Korea Institute of Science and Technology (KIST), Seoul 02792, Republic of Korea
| | - Jae Kwang Lee
- Neuroscience Program, University of Science and Technology (UST), Daejeon 34113, Republic of Korea
| | - Yeonju Bae
- School of Biosystem and Biomedical Science, College of Health Science, Korea University, Seoul 02841, Republic of Korea
| | - Bok-Soon Lee
- Department of Otolaryngology, Ajou University School of Medicine, Suwon 16499, Republic of Korea
| | - Eunju Kim
- School of Biosystem and Biomedical Science, College of Health Science, Korea University, Seoul 02841, Republic of Korea.,Center for Functional Connectomics, Korea Institute of Science and Technology (KIST), Seoul 02792, Republic of Korea
| | - Chang-Hoon Cho
- School of Biosystem and Biomedical Science, College of Health Science, Korea University, Seoul 02841, Republic of Korea
| | - Kanghyun Ryoo
- School of Biosystem and Biomedical Science, College of Health Science, Korea University, Seoul 02841, Republic of Korea
| | - Jiyun Yoo
- Division of Applied Life Science (BK21 plus), Research Institute of Life Sciences, Gyeongsang National University, Jinju 52828, Korea
| | - Chul-Ho Kim
- Department of Otolaryngology, Ajou University School of Medicine, Suwon 16499, Republic of Korea
| | - Gwan-Su Yi
- Department of Bio and Brain Engineering, KAIST, Daejeon 34141, Republic of Korea
| | - Seok-Geun Lee
- Department of Science in Korean Medicine, College of Korean Medicine, KHU-KIST department of Convergging Science and Technology, Kyung Hee University, Seoul 02447, Republic of Korea
| | - C Justin Lee
- Center for Functional Connectomics, Korea Institute of Science and Technology (KIST), Seoul 02792, Republic of Korea.,Neuroscience Program, University of Science and Technology (UST), Daejeon 34113, Republic of Korea
| | - Sang Soo Kang
- Department of Anatomy and Convergence Medical Science, Institute of Health Sciences, School of Medicine, Gyeongsang National University, Jinju 52727, Republic of Korea
| | - Eun Mi Hwang
- Center for Functional Connectomics, Korea Institute of Science and Technology (KIST), Seoul 02792, Republic of Korea.,Neuroscience Program, University of Science and Technology (UST), Daejeon 34113, Republic of Korea
| | - Jae-Yong Park
- School of Biosystem and Biomedical Science, College of Health Science, Korea University, Seoul 02841, Republic of Korea
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138
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Wu MM, Lou J, Song BL, Gong YF, Li YC, Yu CJ, Wang QS, Ma TX, Ma K, Hartzell HC, Duan DD, Zhao D, Zhang ZR. Hypoxia augments the calcium-activated chloride current carried by anoctamin-1 in cardiac vascular endothelial cells of neonatal mice. Br J Pharmacol 2016; 171:3680-92. [PMID: 24758567 PMCID: PMC4128065 DOI: 10.1111/bph.12730] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Revised: 04/01/2014] [Accepted: 04/06/2014] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND AND PURPOSE The molecular identity of calcium-activated chloride channels (CaCCs) in vascular endothelial cells remains unknown. This study sought to identify whether anoctamin-1 (Ano1, also known as TMEM16A) functions as a CaCC and whether hypoxia alters the biophysical properties of Ano1 in mouse cardiac vascular endothelial cells (CVECs). EXPERIMENTAL APPROACH Western blot, quantitative real-time PCR, confocal imaging analysis and patch-clamp analysis combined with pharmacological approaches were used to determine whether Ano1 was expressed and functioned as CaCC in CVECs. KEY RESULTS Ano1 was expressed in CVECs. The biophysical properties of the current generated in the CVECs, including the Ca2+ and voltage dependence, outward rectification, anion selectivity and the pharmacological profile, are similar to those described for CaCCs. The density of ICl(Ca) detected in CVECs was significantly inhibited by T16Ainh-A01, an Ano1 inhibitor, and a pore-targeting, specific anti-Ano1 antibody, and was markedly decreased in Ano1 gene knockdown CVECs. The density of ICl(Ca) was significantly potentiated in CVECs exposed to hypoxia, and this hypoxia-induced increase in the density of ICl(Ca) was inhibited by T16Ainh-A01 or anti-Ano1 antibody. Hypoxia also increased the current density of ICl(Ca) in Ano1 gene knockdown CVECs. CONCLUSIONS AND IMPLICATIONS Ano1 formed CaCC in CVECs of neonatal mice. Hypoxia enhances Ano1-mediated ICl(Ca) density via increasing its expression, altering the ratio of its splicing variants, sensitivity to membrane voltage and to Ca2+. Ano1 may play a role in the pathophysiological processes during ischaemia in heart, and therefore, Ano1 might be a potential therapeutic target to prevent ischaemic damage.
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Affiliation(s)
- Ming-Ming Wu
- Departments of Clinical Pharmacy and Cardiology, Institute of Clinical Pharmacy, The 2nd Affiliated Hospital, Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin Medical University, Harbin, China
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139
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Zhang CH, Wang P, Liu DH, Chen CP, Zhao W, Chen X, Chen C, He WQ, Qiao YN, Tao T, Sun J, Peng YJ, Lu P, Zheng K, Craige SM, Lifshitz LM, Keaney JF, Fogarty KE, ZhuGe R, Zhu MS. The molecular basis of the genesis of basal tone in internal anal sphincter. Nat Commun 2016; 7:11358. [PMID: 27101932 PMCID: PMC4844698 DOI: 10.1038/ncomms11358] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 03/16/2016] [Indexed: 02/06/2023] Open
Abstract
Smooth muscle sphincters exhibit basal tone and control passage of contents through organs such as the gastrointestinal tract; loss of this tone leads to disorders such as faecal incontinence. However, the molecular mechanisms underlying this tone remain unknown. Here, we show that deletion of myosin light-chain kinases (MLCK) in the smooth muscle cells from internal anal sphincter (IAS-SMCs) abolishes basal tone, impairing defecation. Pharmacological regulation of ryanodine receptors (RyRs), L-type voltage-dependent Ca2+ channels (VDCCs) or TMEM16A Ca2+-activated Cl− channels significantly changes global cytosolic Ca2+ concentration ([Ca2+]i) and the tone. TMEM16A deletion in IAS-SMCs abolishes the effects of modulators for TMEM16A or VDCCs on a RyR-mediated rise in global [Ca2+]i and impairs the tone and defecation. Hence, MLCK activation in IAS-SMCs caused by a global rise in [Ca2+]i via a RyR-TMEM16A-VDCC signalling module sets the basal tone. Targeting this module may lead to new treatments for diseases like faecal incontinence. The molecular basis of the basal tone generated by internal anal sphincters (IAS) is largely unknown. Here, the authors show that the tone arises from a global rise in intracellular Ca2+ in smooth muscle cells via a Ryanodine receptor-TMEM16A-L-type Ca2+ channel-MLC kinase pathway, suggesting a potential therapy for IAS motility disorders.
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Affiliation(s)
- Cheng-Hai Zhang
- State Key Laboratory of Pharmaceutical Biotechnology and Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing 210061, China.,Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Pei Wang
- State Key Laboratory of Pharmaceutical Biotechnology and Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing 210061, China
| | - Dong-Hai Liu
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Cai-Ping Chen
- State Key Laboratory of Pharmaceutical Biotechnology and Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing 210061, China
| | - Wei Zhao
- State Key Laboratory of Pharmaceutical Biotechnology and Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing 210061, China
| | - Xin Chen
- State Key Laboratory of Pharmaceutical Biotechnology and Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing 210061, China
| | - Chen Chen
- State Key Laboratory of Pharmaceutical Biotechnology and Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing 210061, China
| | - Wei-Qi He
- State Key Laboratory of Pharmaceutical Biotechnology and Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing 210061, China.,CAM-SU Genomic Resource Center, Soochow University, Suzhou 215123, China
| | - Yan-Ning Qiao
- State Key Laboratory of Pharmaceutical Biotechnology and Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing 210061, China
| | - Tao Tao
- State Key Laboratory of Pharmaceutical Biotechnology and Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing 210061, China
| | - Jie Sun
- State Key Laboratory of Pharmaceutical Biotechnology and Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing 210061, China
| | - Ya-Jing Peng
- State Key Laboratory of Pharmaceutical Biotechnology and Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing 210061, China
| | - Ping Lu
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Kaizhi Zheng
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Siobhan M Craige
- Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA
| | - Lawrence M Lifshitz
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - John F Keaney
- Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA
| | - Kevin E Fogarty
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Ronghua ZhuGe
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Min-Sheng Zhu
- State Key Laboratory of Pharmaceutical Biotechnology and Model Animal Research Center and MOE Key Laboratory of Model Animal for Disease Study, Nanjing University, Nanjing 210061, China.,Innovation Center for Cardiovascular Disorders, Beijing 100029, China
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140
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Liu S, Feng J, Luo J, Yang P, Brett TJ, Hu H. Eact, a small molecule activator of TMEM16A, activates TRPV1 and elicits pain- and itch-related behaviours. Br J Pharmacol 2016; 173:1208-18. [PMID: 26756551 DOI: 10.1111/bph.13420] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Revised: 12/10/2015] [Accepted: 12/22/2015] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND AND PURPOSE TMEM16A, also known as anoctamin 1 channel, is a member of the Ca(2+)-activated chloride channels family and serves as a heat sensor in the primary nociceptors. Eact is a recently discovered small molecule activator of the TMEM16A channel. Here, we asked if Eact produces pain- and itch-related responses in vivo and investigated the cellular and molecular basis of Eact-elicited responses in dorsal root ganglia (DRG) neurons. EXPERIMENTAL APPROACH We employed behavioural testing combined with pharmacological inhibition and genetic ablation approaches to identify transient receptor potential vanilloid 1 (TRPV1) as the prominent mediator for Eact-evoked itch- or pain-related responses. We investigated the effects of Eact on TRPV1 and TMEM16A channels expressed in HEK293T cells and in DRG neurons isolated from wild type and Trpv1(-/-) mice using Ca(2+) imaging and patch-clamp recordings. We also used site-directed mutagenesis to determine the molecular basis of Eact activation of TRPV1. KEY RESULTS Administration of Eact elicited both itch- and pain-related behaviours. Unexpectedly, the Eact-elicited behavioural responses were dependent on the function of TRPV1, as shown by pharmacological inhibition and genetic ablation studies. Eact activated membrane currents and increased intracellular free Ca(2+) in both TRPV1-expressing HEK293T cells and isolated DRG neurons in a TRPV1-dependent manner. Eact activation of the TRPV1 channel was severely attenuated by mutations disrupting the capsaicin-binding sites. CONCLUSIONS AND IMPLICATIONS Our results suggest that Eact activates primary sensory nociceptors and produces both pain and itch responses mainly through direct activation of TRPV1 channels.
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Affiliation(s)
- Shenbin Liu
- Department of Anesthesiology, The Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO, 63110, USA.,Department of Integrative Medicine and Neurobiology, State Key Laboratory of Medical Neurobiology, Shanghai Medical College, Fudan University, Shanghai, 200032, China
| | - Jing Feng
- Department of Anesthesiology, The Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Jialie Luo
- Department of Anesthesiology, The Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Pu Yang
- Department of Anesthesiology, The Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Thomas J Brett
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Hongzhen Hu
- Department of Anesthesiology, The Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO, 63110, USA
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141
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Bill A, Gutierrez A, Kulkarni S, Kemp C, Bonenfant D, Voshol H, Duvvuri U, Gaither LA. ANO1/TMEM16A interacts with EGFR and correlates with sensitivity to EGFR-targeting therapy in head and neck cancer. Oncotarget 2016; 6:9173-88. [PMID: 25823819 PMCID: PMC4496210 DOI: 10.18632/oncotarget.3277] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 02/07/2015] [Indexed: 12/23/2022] Open
Abstract
The epidermal growth factor receptor (EGFR) contributes to the pathogenesis of head&neck squamous cell carcinoma (HNSCC). However, only a subset of HNSCC patients benefit from anti-EGFR targeted therapy. By performing an unbiased proteomics screen, we found that the calcium-activated chloride channel ANO1 interacts with EGFR and facilitates EGFR-signaling in HNSCC. Using structural mutants of EGFR and ANO1 we identified the trans/juxtamembrane domain of EGFR to be critical for the interaction with ANO1. Our results show that ANO1 and EGFR form a functional complex that jointly regulates HNSCC cell proliferation. Expression of ANO1 affected EGFR stability, while EGFR-signaling elevated ANO1 protein levels, establishing a functional and regulatory link between ANO1 and EGFR. Co-inhibition of EGFR and ANO1 had an additive effect on HNSCC cell proliferation, suggesting that co-targeting of ANO1 and EGFR could enhance the clinical potential of EGFR-targeted therapy in HNSCC and might circumvent the development of resistance to single agent therapy. HNSCC cell lines with amplification and high expression of ANO1 showed enhanced sensitivity to Gefitinib, suggesting ANO1 overexpression as a predictive marker for the response to EGFR-targeting agents in HNSCC therapy. Taken together, our results introduce ANO1 as a promising target and/or biomarker for EGFR-directed therapy in HNSCC.
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Affiliation(s)
- Anke Bill
- Novartis Institutes for Biomedical Research, Cambridge, MA 02139, USA
| | - Abraham Gutierrez
- Novartis Institutes for Biomedical Research, Cambridge, MA 02139, USA
| | - Sucheta Kulkarni
- University of Pittsburgh, Medical Center, Department of Otolaryngology, Pittsburgh, PA 15213, USA
| | - Carolyn Kemp
- University of Pittsburgh, Medical Center, Department of Otolaryngology, Pittsburgh, PA 15213, USA
| | - Debora Bonenfant
- Novartis Institutes for Biomedical Research, Basel, CH-4002, Switzerland
| | - Hans Voshol
- Novartis Institutes for Biomedical Research, Basel, CH-4002, Switzerland
| | - Umamaheswar Duvvuri
- University of Pittsburgh, Medical Center, Department of Otolaryngology, Pittsburgh, PA 15213, USA.,VA Pittsburgh HealthCare System, Pittsburgh, PA 15213, USA
| | - L Alex Gaither
- Novartis Institutes for Biomedical Research, Cambridge, MA 02139, USA
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142
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Ohya S, Kito H, Hatano N, Muraki K. Recent advances in therapeutic strategies that focus on the regulation of ion channel expression. Pharmacol Ther 2016; 160:11-43. [PMID: 26896566 DOI: 10.1016/j.pharmthera.2016.02.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
A number of different ion channel types are involved in cell signaling networks, and homeostatic regulatory mechanisms contribute to the control of ion channel expression. Profiling of global gene expression using microarray technology has recently provided novel insights into the molecular mechanisms underlying the homeostatic and pathological control of ion channel expression. It has demonstrated that the dysregulation of ion channel expression is associated with the pathogenesis of neural, cardiovascular, and immune diseases as well as cancers. In addition to the transcriptional, translational, and post-translational regulation of ion channels, potentially important evidence on the mechanisms controlling ion channel expression has recently been accumulated. The regulation of alternative pre-mRNA splicing is therefore a novel therapeutic strategy for the treatment of dominant-negative splicing disorders. Epigenetic modification plays a key role in various pathological conditions through the regulation of pluripotency genes. Inhibitors of pre-mRNA splicing and histone deacetyalase/methyltransferase have potential as potent therapeutic drugs for cancers and autoimmune and inflammatory diseases. Moreover, membrane-anchoring proteins, lysosomal and proteasomal degradation-related molecules, auxiliary subunits, and pharmacological agents alter the protein folding, membrane trafficking, and post-translational modifications of ion channels, and are linked to expression-defect channelopathies. In this review, we focused on recent insights into the transcriptional, spliceosomal, epigenetic, and proteasomal regulation of ion channel expression: Ca(2+) channels (TRPC/TRPV/TRPM/TRPA/Orai), K(+) channels (voltage-gated, KV/Ca(2+)-activated, KCa/two-pore domain, K2P/inward-rectifier, Kir), and Ca(2+)-activated Cl(-) channels (TMEM16A/TMEM16B). Furthermore, this review highlights expression of these ion channels in expression-defect channelopathies.
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Affiliation(s)
- Susumu Ohya
- Department of Pharmacology, Division of Pathological Sciences, Kyoto Pharmaceutical University, Kyoto 607-8414, Japan.
| | - Hiroaki Kito
- Department of Pharmacology, Division of Pathological Sciences, Kyoto Pharmaceutical University, Kyoto 607-8414, Japan
| | - Noriyuki Hatano
- Laboratory of Cellular Pharmacology, School of Pharmacy, Aichi-Gakuin University, Nagoya 464-8650, Japan
| | - Katsuhiko Muraki
- Laboratory of Cellular Pharmacology, School of Pharmacy, Aichi-Gakuin University, Nagoya 464-8650, Japan.
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143
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Abstract
Ca2+-activated Cl− channels (CaCCs) are a class of Cl− channels activated by intracellular Ca2+ that are known to mediate numerous physiological functions. In 2008, the molecular identity of CaCCs was found to be anoctamin 1 (ANO1/TMEM16A). Its roles have been studied in electrophysiological, histological, and genetic aspects. ANO1 is known to mediate Cl− secretion in secretory epithelia such as airways, salivary glands, intestines, renal tubules, and sweat glands. ANO1 is a heat sensor activated by noxious heat in somatosensory neurons and mediates acute pain sensation as well as chronic pain. ANO1 is also observed in vascular as well as airway smooth muscles, controlling vascular tone as well as airway hypersensitivity. ANO1 is upregulated in numerous types of cancers and thus thought to be involved in tumorigenesis. ANO1 is also found in proliferating cells. In addition to ANO1, involvement of its paralogs in pathophysiological conditions was also reported. ANO2 is involved in olfaction, whereas ANO6 works as a scramblase whose mutation causes a rare bleeding disorder, the Scott syndrome. ANO5 is associated with muscle and bone diseases. Recently, an X-ray crystal structure of a fungal TMEM16 was reported, which explains a precise molecular gating mechanism as well as ion conduction or phospholipid transport across the plasma membrane.
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144
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Piechowicz KA, Truong EC, Javed KM, Chaney RR, Wu JY, Phuan PW, Verkman AS, Anderson MO. Synthesis and evaluation of 5,6-disubstituted thiopyrimidine aryl aminothiazoles as inhibitors of the calcium-activated chloride channel TMEM16A/Ano1. J Enzyme Inhib Med Chem 2016; 31:1362-8. [PMID: 26796863 DOI: 10.3109/14756366.2015.1135912] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Transmembrane protein 16A (TMEM16A), also called Ano1, is a Ca(2+) activated Cl(-) channel expressed widely in mammalian epithelia, as well as in vascular smooth muscle and some tumors and electrically excitable cells. TMEM16A inhibitors have potential utility for treatment of disorders of epithelial fluid and mucus secretion, hypertension, some cancers and other diseases. 4-Aryl-2-amino thiazole T16Ainh-01 was previously identified by high-throughput screening. Here, a library of 47 compounds were prepared that explored the 5,6-disubstituted pyrimidine scaffold found in T16Ainh-01. TMEM16A inhibition activity was measured using fluorescence plate reader and short-circuit current assays. We found that very little structural variation of T16Ainh-01 was tolerated, with most compounds showing no activity at 10 μM. The most potent compound in the series, 9bo, which substitutes 4-methoxyphenyl in T16Ainh-01 with 2-thiophene, had IC50 ∼1 μM for inhibition of TMEM16A chloride conductance.
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Affiliation(s)
- Katarzyna A Piechowicz
- a Department of Chemistry and Biochemistry , San Francisco State University , San Francisco , CA , USA and
| | - Eric C Truong
- a Department of Chemistry and Biochemistry , San Francisco State University , San Francisco , CA , USA and
| | - Kashif M Javed
- a Department of Chemistry and Biochemistry , San Francisco State University , San Francisco , CA , USA and
| | - Rachelle R Chaney
- a Department of Chemistry and Biochemistry , San Francisco State University , San Francisco , CA , USA and
| | - Johnny Y Wu
- a Department of Chemistry and Biochemistry , San Francisco State University , San Francisco , CA , USA and
| | - Puay W Phuan
- b Departments of Medicine and Physiology , University of California, San Francisco , San Francisco , CA , USA
| | - Alan S Verkman
- b Departments of Medicine and Physiology , University of California, San Francisco , San Francisco , CA , USA
| | - Marc O Anderson
- a Department of Chemistry and Biochemistry , San Francisco State University , San Francisco , CA , USA and
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145
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Novel Roles for Chloride Channels, Exchangers, and Regulators in Chronic Inflammatory Airway Diseases. Mediators Inflamm 2015; 2015:497387. [PMID: 26612971 PMCID: PMC4647060 DOI: 10.1155/2015/497387] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 10/13/2015] [Indexed: 01/14/2023] Open
Abstract
Chloride transport proteins play critical roles in inflammatory airway diseases, contributing to the detrimental aspects of mucus overproduction, mucus secretion, and airway constriction. However, they also play crucial roles in contributing to the innate immune properties of mucus and mucociliary clearance. In this review, we focus on the emerging novel roles for a chloride channel regulator (CLCA1), a calcium-activated chloride channel (TMEM16A), and two chloride exchangers (SLC26A4/pendrin and SLC26A9) in chronic inflammatory airway diseases.
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146
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Sun Y, Birnbaumer L, Singh BB. TRPC1 regulates calcium-activated chloride channels in salivary gland cells. J Cell Physiol 2015; 230:2848-56. [PMID: 25899321 PMCID: PMC4872598 DOI: 10.1002/jcp.25017] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Accepted: 04/14/2015] [Indexed: 12/19/2022]
Abstract
Calcium-activated chloride channel (CaCC) plays an important role in modulating epithelial secretion. It has been suggested that in salivary tissues, sustained fluid secretion is dependent on Ca(2+) influx that activates ion channels such as CaCC to initiate Cl(-) efflux. However direct evidence as well as the molecular identity of the Ca(2+) channel responsible for activating CaCC in salivary tissues is not yet identified. Here we provide evidence that in human salivary cells, an outward rectifying Cl(-) current was activated by increasing [Ca(2+)]i, which was inhibited by the addition of pharmacological agents niflumic acid (NFA), an antagonist of CaCC, or T16Ainh-A01, a specific TMEM16a inhibitor. Addition of thapsigargin (Tg), that induces store-depletion and activates TRPC1-mediated Ca(2+) entry, potentiated the Cl(-) current, which was inhibited by the addition of a non-specific TRPC channel blocker SKF96365 or removal of external Ca(2+). Stimulation with Tg also increased plasma membrane expression of TMEM16a protein, which was also dependent on Ca(2+) entry. Importantly, in salivary cells, TRPC1 silencing, but not that of TRPC3, inhibited CaCC especially upon store depletion. Moreover, primary acinar cells isolated from submandibular gland also showed outward rectifying Cl(-) currents upon increasing [Ca(2+)]i. These Cl(-) currents were again potentiated with the addition of Tg, but inhibited in the presence of T16Ainh-A01. Finally, acinar cells isolated from the submandibular glands of TRPC1 knockout mice showed significant inhibition of the outward Cl(-) currents without decreasing TMEM16a expression. Together the data suggests that Ca(2+) entry via the TRPC1 channels is essential for the activation of CaCC.
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Affiliation(s)
- Yuyang Sun
- Department of Basic Sciences, School of Medicine Health Sciences, University of North Dakota, Grand Forks, North Dakota
| | - Lutz Birnbaumer
- Laboratory of Signal Transduction, NIHES, NIH, Research Triangle Park, North Carolina
| | - Brij B Singh
- Department of Basic Sciences, School of Medicine Health Sciences, University of North Dakota, Grand Forks, North Dakota
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147
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Scudieri P, Caci E, Venturini A, Sondo E, Pianigiani G, Marchetti C, Ravazzolo R, Pagani F, Galietta LJV. Ion channel and lipid scramblase activity associated with expression of TMEM16F/ANO6 isoforms. J Physiol 2015; 593:3829-48. [PMID: 26108457 PMCID: PMC4575572 DOI: 10.1113/jp270691] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Accepted: 05/26/2015] [Indexed: 11/08/2022] Open
Abstract
TMEM16F is a membrane protein with possible dual function as an ion channel and a phospholipid scramblase. The properties of ion channels associated with TMEM16F and the link between ion channel and scramblase activity are a matter of debate. We studied the properties of four isoforms of TMEM16F generated by alternative splicing. Upregulation of three TMEM16F isoforms or silencing of endogenous TMEM16F increased and decreased, respectively, both scramblase and channel activities. Introduction of an activating mutation in TMEM16F sequence caused a marked increase in phosphatidylserine scrambling and in ion transport indicating direct involvement of the protein in both functions. TMEM16F, also known as ANO6, is a membrane protein that has been associated with phospholipid scramblase and ion channel activity. However, the characteristics of TMEM16F-dependent channels, particularly the ion selectivity, are a matter of debate. Furthermore, the direct involvement of TMEM16F in phospholipid scrambling has been questioned. We studied the properties of different TMEM16F variants generated by alternative splicing. Using whole-cell patch-clamp recordings, we found that V1, V2 and V5 variants generated membrane currents activated by very high (micromolar) intracellular Ca(2+) concentrations and positive membrane potentials. These variants showed different degrees of Ca(2+) sensitivity and kinetics of activation but similar ion permeability, characterized by a slight selectivity for Cl(-) over Na(+) . A fourth variant (V3) showing a unique carboxy-terminus was devoid of activity, in agreement with its intracellular localization. We also measured scramblase activity using the binding of annexin V to detect phosphatidylserine on the cell surface. V1, V2 and V5 variants were associated with calcium-dependent phosphatidylserine externalization. Interestingly, introduction of an activating mutation, D409G, produced a marked increase in the apparent Ca(2+) sensitivity of TMEM16F-dependent channels. In parallel, this mutation also enhanced the extent of phosphatidylserine externalization that occurred even under resting conditions. These results support the conclusion that TMEM16F proteins are directly involved in dual activity, as a phospholipid scramblase and as an ion channel.
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Affiliation(s)
| | | | | | | | - Giulia Pianigiani
- Human Molecular Genetics, International Centre for Genetic Engineering and BiotechnologyTrieste, Italy
| | | | - Roberto Ravazzolo
- Istituto Giannina GasliniGenova, Italy
- DINOGMI, University of GenovaItaly
| | - Franco Pagani
- Human Molecular Genetics, International Centre for Genetic Engineering and BiotechnologyTrieste, Italy
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O'Grady G, Wang THH, Du P, Angeli T, Lammers WJEP, Cheng LK. Recent progress in gastric arrhythmia: pathophysiology, clinical significance and future horizons. Clin Exp Pharmacol Physiol 2015; 41:854-62. [PMID: 25115692 DOI: 10.1111/1440-1681.12288] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Revised: 07/11/2014] [Accepted: 07/14/2014] [Indexed: 01/27/2023]
Abstract
Gastric arrhythmia continues to be of uncertain diagnostic and therapeutic significance. However, recent progress has been substantial, with technical advances, theoretical insights and experimental discoveries offering new translational opportunities. The discoveries that interstitial cells of Cajal (ICC) generate slow waves and that ICC defects are associated with dysmotility have reinvigorated gastric arrhythmia research. Increasing evidence now suggests that ICC depletion and damage, network disruption and channelopathies may lead to aberrant slow wave initiation and conduction. Histological and high-resolution (HR) electrical mapping studies have now redefined the human 'gastric conduction system', providing an improved baseline for arrhythmia research. The application of HR mapping to arrhythmia has also generated important new insights into the spatiotemporal dynamics of arrhythmia onset and maintenance, resulting in the emergence of new provisional classification schemes. Meanwhile, the strong associations between gastric functional disorders and electrogastrography (EGG) abnormalities (e.g. in gastroparesis, unexplained nausea and vomiting and functional dyspepsia) continue to motivate deeper inquiries into the nature and causes of gastrointestinal arrhythmias. In future, technical progress in EGG methods, new HR mapping devices and software, wireless slow wave acquisition systems and improved gastric pacing devices may achieve validated applications in clinical practice. Neurohormonal factors in arrhythmogenesis also continue to be elucidated and a deepening understanding of these mechanisms may open opportunities for drug design for treating arrhythmias. However, for all translational goals, it remains to be seen whether arrhythmia can be corrected in a way that meaningfully improves organ function and symptoms in patients.
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Affiliation(s)
- Gregory O'Grady
- Department of Surgery, The University of Auckland, Auckland, New Zealand; Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
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Bradley E, Fedigan S, Webb T, Hollywood MA, Thornbury KD, McHale NG, Sergeant GP. Pharmacological characterization of TMEM16A currents. Channels (Austin) 2015; 8:308-20. [PMID: 24642630 DOI: 10.4161/chan.28065] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Recent studies have shown that transmembrane protein 16 A (TMEM16A) is a subunit of calcium-activated chloride channels (CACCs). Pharmacological agents have been used to probe the functional role of CACCs, however their effect on TMEM16A currents has not been systematically investigated. In the present study, we characterized the voltage and concentration-dependent effects of 2 traditional CACC inhibitors (niflumic acid and anthracene-9-carboxcylic acid) and 2 novel CACC / TMEM16A inhibitors (CACC(inh)A01 and T16A(inh)A01) on TMEM16A currents. The whole cell patch clamp technique was used to record TMEM16A currents from HE K 293 cells that stably expressed human TMEM16A. Niflumic acid, A-9-C, CACC(inh)A01 and T16A(inh)A01 inhibited TMEM16A currents with IC50 values of 12, 58, 1.7 and 1.5 μM, respectively, however, A-9-C and niflumic acid were less efficacious at negative membrane potentials. A-9-C and niflumic acid reduced the rate of TMEM16A tail current deactivation at negative membrane potentials and A-9-C (1 mM) enhanced peak TMEM16A tail current amplitude. In contrast, the inhibitory effects of CACC(inh)A01 and T16A(inh)A01 were independent of voltage and they did not prolong the rate of TMEM16A tail current deactivation. The effects of niflumic acid and A-9-C on TMEM16A currents were similar to previous observations on CACCs in vascular smooth muscle, strengthening the hypothesis that they are encoded by TMEM16A. However, CACC(inh)A01 and T16A(inh)A01 were more potent inhibitors of TMEM16A channels and their effects were not diminished at negative membrane potentials making them attractive candidates to interrogate the functional role of TMEM16A channels in future studies.
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150
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Leblanc N, Forrest AS, Ayon RJ, Wiwchar M, Angermann JE, Pritchard HAT, Singer CA, Valencik ML, Britton F, Greenwood IA. Molecular and functional significance of Ca(2+)-activated Cl(-) channels in pulmonary arterial smooth muscle. Pulm Circ 2015; 5:244-68. [PMID: 26064450 DOI: 10.1086/680189] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 07/22/2014] [Indexed: 12/31/2022] Open
Abstract
Increased peripheral resistance of small distal pulmonary arteries is a hallmark signature of pulmonary hypertension (PH) and is believed to be the consequence of enhanced vasoconstriction to agonists, thickening of the arterial wall due to remodeling, and increased thrombosis. The elevation in arterial tone in PH is attributable, at least in part, to smooth muscle cells of PH patients being more depolarized and displaying higher intracellular Ca(2+) levels than cells from normal subjects. It is now clear that downregulation of voltage-dependent K(+) channels (e.g., Kv1.5) and increased expression and activity of voltage-dependent (Cav1.2) and voltage-independent (e.g., canonical and vanilloid transient receptor potential [TRPC and TRPV]) Ca(2+) channels play an important role in the functional remodeling of pulmonary arteries in PH. This review focuses on an anion-permeable channel that is now considered a novel excitatory mechanism in the systemic and pulmonary circulations. It is permeable to Cl(-) and is activated by a rise in intracellular Ca(2+) concentration (Ca(2+)-activated Cl(-) channel, or CaCC). The first section outlines the biophysical and pharmacological properties of the channel and ends with a description of the molecular candidate genes postulated to encode for CaCCs, with particular emphasis on the bestrophin and the newly discovered TMEM16 and anoctamin families of genes. The second section provides a review of the various sources of Ca(2+) activating CaCCs, which include stimulation by mobilization from intracellular Ca(2+) stores and Ca(2+) entry through voltage-dependent and voltage-independent Ca(2+) channels. The third and final section summarizes recent findings that suggest a potentially important role for CaCCs and the gene TMEM16A in PH.
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Affiliation(s)
- Normand Leblanc
- Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada, USA
| | - Abigail S Forrest
- Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada, USA
| | - Ramon J Ayon
- Department of Medicine, University of Illinois, Chicago, Illinois, USA
| | - Michael Wiwchar
- Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada, USA
| | - Jeff E Angermann
- School of Community Health Sciences, University of Nevada, Reno, Nevada, USA
| | - Harry A T Pritchard
- Vascular Biology Research Centre, Institute of Cardiovascular and Cell Sciences, St. George's University of London, London, United Kingdom
| | - Cherie A Singer
- Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada, USA
| | - Maria L Valencik
- Department of Biochemistry and Molecular Biology, University of Nevada School of Medicine, Reno, Nevada, USA
| | - Fiona Britton
- Department of Physiology, School of Medical Sciences, University of New South Wales, Sydney, Australia
| | - Iain A Greenwood
- Vascular Biology Research Centre, Institute of Cardiovascular and Cell Sciences, St. George's University of London, London, United Kingdom
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