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Jimenez C, Hawn MB, Akin E, Leblanc N. Translational potential of targeting Anoctamin-1-Encoded Calcium-Activated chloride channels in hypertension. Biochem Pharmacol 2022; 206:115320. [PMID: 36279919 DOI: 10.1016/j.bcp.2022.115320] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Revised: 10/13/2022] [Accepted: 10/17/2022] [Indexed: 12/14/2022]
Abstract
Calcium-activated chloride channels (CaCC) provide a depolarizing stimulus to a variety of tissues through chloride efflux in response to a rise in internal Ca2+ and voltage. One of these channels, Anoctamin-1 (ANO1 or TMEM16A) is now recognized to play a central role in promoting smooth muscle tone in various types of blood vessels. Its role in hypertension, and thus the therapeutic promise of targeting ANO1, is less straightforward. This review gives an overview of our current knowledge about the potential role ANO1 may play in hypertension within the systemic, portal, and pulmonary vascular systems and the importance of this information when pursuing potential treatment strategies. While the role of ANO1 is well-established in several forms of pulmonary hypertension, its contributions to both the generation of vascular tone and its role in hypertension within the systemic and portal systems are much less clear. This, combined with ANO1's various roles throughout a multitude of tissues throughout the body, command caution when targeting ANO1 as a therapeutic target and may require tissue-selective strategies.
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Affiliation(s)
- Connor Jimenez
- Department of Pharmacology and Center of Biomedical Research Excellence (COBRE) for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, 1664 North Virginia Street, Reno, Nevada 89557, USA
| | - Matthew B Hawn
- Department of Pharmacology and Center of Biomedical Research Excellence (COBRE) for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, 1664 North Virginia Street, Reno, Nevada 89557, USA
| | - Elizabeth Akin
- Department of Pharmacology and Center of Biomedical Research Excellence (COBRE) for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, 1664 North Virginia Street, Reno, Nevada 89557, USA
| | - Normand Leblanc
- Department of Pharmacology and Center of Biomedical Research Excellence (COBRE) for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, 1664 North Virginia Street, Reno, Nevada 89557, USA.
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Polymodal Control of TMEM16x Channels and Scramblases. Int J Mol Sci 2022; 23:ijms23031580. [PMID: 35163502 PMCID: PMC8835819 DOI: 10.3390/ijms23031580] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2021] [Revised: 01/20/2022] [Accepted: 01/20/2022] [Indexed: 02/01/2023] Open
Abstract
The TMEM16A/anoctamin-1 calcium-activated chloride channel (CaCC) contributes to a range of vital functions, such as the control of vascular tone and epithelial ion transport. The channel is a founding member of a family of 10 proteins (TMEM16x) with varied functions; some members (i.e., TMEM16A and TMEM16B) serve as CaCCs, while others are lipid scramblases, combine channel and scramblase function, or perform additional cellular roles. TMEM16x proteins are typically activated by agonist-induced Ca2+ release evoked by Gq-protein-coupled receptor (GqPCR) activation; thus, TMEM16x proteins link Ca2+-signalling with cell electrical activity and/or lipid transport. Recent studies demonstrate that a range of other cellular factors—including plasmalemmal lipids, pH, hypoxia, ATP and auxiliary proteins—also control the activity of the TMEM16A channel and its paralogues, suggesting that the TMEM16x proteins are effectively polymodal sensors of cellular homeostasis. Here, we review the molecular pathophysiology, structural biology, and mechanisms of regulation of TMEM16x proteins by multiple cellular factors.
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Wray S, Prendergast C, Arrowsmith S. Calcium-Activated Chloride Channels in Myometrial and Vascular Smooth Muscle. Front Physiol 2021; 12:751008. [PMID: 34867456 PMCID: PMC8637852 DOI: 10.3389/fphys.2021.751008] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Accepted: 09/24/2021] [Indexed: 11/24/2022] Open
Abstract
In smooth muscle tissues, calcium-activated chloride channels (CaCC) provide the major anionic channel. Opening of these channels leads to chloride efflux and depolarization of the myocyte membrane. In this way, activation of the channels by a rise of intracellular [Ca2+], from a variety of sources, produces increased excitability and can initiate action potentials and contraction or increased tone. We now have a good mechanistic understanding of how the channels are activated and regulated, due to identification of TMEM16A (ANO1) as the molecular entity of the channel, but key questions remain. In reviewing these channels and comparing two distinct smooth muscles, myometrial and vascular, we expose the differences that occur in their activation mechanisms, properties, and control. We find that the myometrium only expresses “classical,” Ca2+-activated, and voltage sensitive channels, whereas both tonic and phasic blood vessels express classical, and non-classical, cGMP-regulated CaCC, which are voltage insensitive. This translates to more complex activation and regulation in vascular smooth muscles, irrespective of whether they are tonic or phasic. We therefore tentatively conclude that although these channels are expressed and functionally important in all smooth muscles, they are probably not part of the mechanisms governing phasic activity. Recent knockdown studies have produced unexpected functional results, e.g. no effects on labour and delivery, and tone increasing in some but decreasing in other vascular beds, strongly suggesting that there is still much to be explored concerning CaCC in smooth muscle.
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Affiliation(s)
- Susan Wray
- Department of Women and Children's Health, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Clodagh Prendergast
- Department of Women and Children's Health, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Sarah Arrowsmith
- Department of Life Sciences, Manchester Metropolitan University, Manchester, United Kingdom
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Hawn MB, Akin E, Hartzell H, Greenwood IA, Leblanc N. Molecular mechanisms of activation and regulation of ANO1-Encoded Ca 2+-Activated Cl - channels. Channels (Austin) 2021; 15:569-603. [PMID: 34488544 PMCID: PMC8480199 DOI: 10.1080/19336950.2021.1975411] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 08/29/2021] [Indexed: 01/13/2023] Open
Abstract
Ca2+-activated Cl- channels (CaCCs) perform a multitude of functions including the control of cell excitability, regulation of cell volume and ionic homeostasis, exocrine and endocrine secretion, fertilization, amplification of olfactory sensory function, and control of smooth muscle cell contractility. CaCCs are the translated products of two members (ANO1 and ANO2, also known as TMEM16A and TMEM16B) of the Anoctamin family of genes comprising ten paralogs. This review focuses on recent progress in understanding the molecular mechanisms involved in the regulation of ANO1 by cytoplasmic Ca2+, post-translational modifications, and how the channel protein interacts with membrane lipids and protein partners. After first reviewing the basic properties of native CaCCs, we then present a brief historical perspective highlighting controversies about their molecular identity in native cells. This is followed by a summary of the fundamental biophysical and structural properties of ANO1. We specifically address whether the channel is directly activated by internal Ca2+ or indirectly through the intervention of the Ca2+-binding protein Calmodulin (CaM), and the structural domains responsible for Ca2+- and voltage-dependent gating. We then review the regulation of ANO1 by internal ATP, Calmodulin-dependent protein kinase II-(CaMKII)-mediated phosphorylation and phosphatase activity, membrane lipids such as the phospholipid phosphatidyl-(4,5)-bisphosphate (PIP2), free fatty acids and cholesterol, and the cytoskeleton. The article ends with a survey of physical and functional interactions of ANO1 with other membrane proteins such as CLCA1/2, inositol trisphosphate and ryanodine receptors in the endoplasmic reticulum, several members of the TRP channel family, and the ancillary Κ+ channel β subunits KCNE1/5.
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Affiliation(s)
- M. B. Hawn
- Department of Pharmacology and Center of Biomedical Research Excellence for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, Reno, United States
| | - E. Akin
- Department of Pharmacology and Center of Biomedical Research Excellence for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, Reno, United States
| | - H.C. Hartzell
- Department of Cell Biology, Emory University School of Medicine, USA
| | - I. A. Greenwood
- Department of Vascular Pharmacology, St. George’s University of London, UK
| | - N. Leblanc
- Department of Pharmacology and Center of Biomedical Research Excellence for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, Reno, United States
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TMEM16A/ANO1: Current Strategies and Novel Drug Approaches for Cystic Fibrosis. Cells 2021; 10:cells10112867. [PMID: 34831090 PMCID: PMC8616501 DOI: 10.3390/cells10112867] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 10/19/2021] [Accepted: 10/20/2021] [Indexed: 12/19/2022] Open
Abstract
Cystic fibrosis (CF) is the most common of rare hereditary diseases in Caucasians, and it is estimated to affect 75,000 patients globally. CF is a complex disease due to the multiplicity of mutations found in the CF transmembrane conductance regulator (CFTR) gene causing the CFTR protein to become dysfunctional. Correctors and potentiators have demonstrated good clinical outcomes for patients with specific gene mutations; however, there are still patients for whom those treatments are not suitable and require alternative CFTR-independent strategies. Although CFTR is the main chloride channel in the lungs, others could, e.g., anoctamin-1 (ANO1 or TMEM16A), compensate for the deficiency of CFTR. This review summarizes the current knowledge on calcium-activated chloride channel (CaCC) ANO1 and presents ANO1 as an exciting target in CF.
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Calmodulin-Dependent Regulation of Overexpressed but Not Endogenous TMEM16A Expressed in Airway Epithelial Cells. MEMBRANES 2021; 11:membranes11090723. [PMID: 34564540 PMCID: PMC8471323 DOI: 10.3390/membranes11090723] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 09/16/2021] [Accepted: 09/20/2021] [Indexed: 11/30/2022]
Abstract
Regulation of the Ca2+-activated Cl− channel TMEM16A by Ca2+/calmodulin (CAM) is discussed controversially. In the present study, we compared regulation of TMEM16A by Ca2+/calmodulin (holo-CAM), CAM-dependent kinase (CAMKII), and CAM-dependent phosphatase calcineurin in TMEM16A-overexpressing HEK293 cells and TMEM16A expressed endogenously in airway and colonic epithelial cells. The activator of the Ca2+/CAM-regulated K+ channel KCNN4, 1-EBIO, activated TMEM16A in overexpressing cells, but not in cells with endogenous expression of TMEM16A. Evidence is provided that CAM-interaction with TMEM16A modulates the Ca2+ sensitivity of the Cl− channel. Enhanced Ca2+ sensitivity of overexpressed TMEM16A explains its activity at basal (non-elevated) intracellular Ca2+ levels. The present results correspond well to a recent report that demonstrates a Ca2+-unbound form of CAM (apo-CAM) that is pre-associated with TMEM16A and mediates a Ca2+-dependent sensitization of activation (and inactivation). However, when using activators or inhibitors for holo-CAM, CAMKII, or calcineurin, we were unable to detect a significant impact of CAM, and limit evidence for regulation by CAM-dependent regulatory proteins on receptor-mediated activation of endogenous TMEM16A in airway or colonic epithelial cells. We propose that regulatory properties of TMEM16A and and other members of the TMEM16 family as detected in overexpression studies, should be validated for endogenous TMEM16A and physiological stimuli such as activation of phospholipase C (PLC)-coupled receptors.
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Grigoriev VV. [Calcium-activated chloride channels: structure, properties, role in physiological and pathological processes]. BIOMEDIT︠S︡INSKAI︠A︡ KHIMII︠A︡ 2021; 67:17-33. [PMID: 33645519 DOI: 10.18097/pbmc20216701017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Ca2+-activated chloride channels (CaCC) are a class of intracellular calcium activated chloride channels that mediate numerous physiological functions. In 2008, the molecular structure of CaCC was determined. CaCC are formed by the protein known as anoctamine 1 (ANO1 or TMEM16A). CaCC mediates the secretion of Cl- in secretory epithelia, such as the airways, salivary glands, intestines, renal tubules, and sweat glands. The presence of CaCC has also been recognized in the vascular muscles, smooth muscles of the respiratory tract, which control vascular tone and hypersensitivity of the respiratory tract. TMEM16A is activated in many cancers; it is believed that TMEM16A is involved in carcinogenesis. TMEM16A is also involved in cancer cells proliferation. The role of TMEM16A in the mechanisms of hypertension, asthma, cystic fibrosis, nociception, and dysfunction of the gastrointestinal tract has been determined. In addition to TMEM16A, its isoforms are involved in other physiological and pathophysiological processes. TMEM16B (or ANO2) is involved in the sense of smell, while ANO6 works like scramblase, and its mutation causes a rare bleeding disorder, known as Scott syndrome. ANO5 is associated with muscle and bone diseases. TMEM16A interacts with various cellular signaling pathways including: epidermal growth factor receptor (EGFR), mitogen-activated protein kinases (MAPK), calmodulin (CaM) kinases, transforming growth factor TGF-β. The review summarizes existing information on known natural and synthetic compounds that can block/modulate CaCC currents and their effect on some pathologies in which CaCC is involved.
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Affiliation(s)
- V V Grigoriev
- Institute of Physiologically Active Compounds of the Russian Academy of Sciences, Moscow, Russia
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Liu D, Wang K, Su D, Huang Y, Shang L, Zhao Y, Huang J, Pang Y. TMEM16A Regulates Pulmonary Arterial Smooth Muscle Cells Proliferation via p38MAPK/ERK Pathway in High Pulmonary Blood Flow-Induced Pulmonary Arterial Hypertension. J Vasc Res 2020; 58:27-37. [PMID: 33311015 DOI: 10.1159/000511267] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 08/26/2020] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE Pulmonary arterial hypertension (PAH) is a complex disease of the small pulmonary arteries that is mainly characterized by vascular remodeling. It has been demonstrated that excessive proliferation of pulmonary arterial smooth muscle cells (PASMCs) plays a pivotal role in vascular remodeling during PAH. The present study was undertaken to explore the role of TMEM16A in regulating PASMCs proliferation in high pulmonary blood flow-induced PAH. METHODS Aortocaval shunt surgery was undertaken to establish an animal model. Pulmonary artery pressure and pulmonary vascular structure remodeling (PVSR) were tested. Immunohistochemical staining and Western blot were performed to investigate the expression of TMEM16A. The proliferation of PASMCs was tested by the MTT assay. After treating PASMCs with TMEM16A-siRNA, the expression of proliferating cell nuclear antigen (PCNA), phosphorylated p38 mitogen-activated protein kinase (p-p38MAPK), and phosphorylated extracellular signal-regulated kinase (p-ERK) signaling in PASMCs were tested. RESULTS PAH and PVSR developed 11 weeks postoperation. Elevated expression of TMEM16A accompanied by high expression of PCNA in pulmonary arteries of the shunt group was observed. The increased proliferation of PASMCs and increased expression of TMEM16A and PCNA, along with activated p-p38MAPK and p-ERK signaling in PASMCs of the shunt group, were all attenuated by siRNA-specific TMEM16A knockdown. CONCLUSION TMEM16A regulates PASMCs proliferation in high pulmonary blood flow-induced PAH, and the p38MAPK/ERK signaling pathway is probably involved.
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Affiliation(s)
- Dongli Liu
- Department of Pediatrics, The First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Kai Wang
- Department of Pediatrics, The First Affiliated Hospital of Guangxi Medical University, Nanning, China
- Department of Pediatrics, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Danyan Su
- Department of Pediatrics, The First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Yanyun Huang
- Department of Pediatrics, The First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Lifeng Shang
- Department of Pediatrics, The First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Yijue Zhao
- Department of Pediatrics, The First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Jinglin Huang
- Department of Pediatrics, The First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Yusheng Pang
- Department of Pediatrics, The First Affiliated Hospital of Guangxi Medical University, Nanning, China,
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Chang WT, Ragazzi E, Liu PY, Wu SN. Effective block by pirfenidone, an antifibrotic pyridone compound (5-methyl-1-phenylpyridin-2[H-1]-one), on hyperpolarization-activated cation current: An additional but distinctive target. Eur J Pharmacol 2020; 882:173237. [PMID: 32525005 PMCID: PMC7276140 DOI: 10.1016/j.ejphar.2020.173237] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 05/26/2020] [Accepted: 05/29/2020] [Indexed: 12/26/2022]
Abstract
Pirfenidone (PFD), a pyridone compound, is well recognized as an antifibrotic agent tailored for the treatment of idiopathic pulmonary fibrosis. Recently, through its anti-inflammatory and anti-oxidant effects, PFD based clinical trial has also been launched for the treatment of coronavirus disease (COVID-19). To what extent this drug can perturb membrane ion currents remains largely unknown. Herein, the exposure to PFD was observed to depress the amplitude of hyperpolarization-activated cation current (Ih) in combination with a considerable slowing in the activation time of the current in pituitary GH3 cells. In the continued presence of ivabradine or zatebradine, subsequent application of PFD decreased Ih amplitude further. The presence of PFD resulted in a leftward shift in Ih activation curve without changes in the gating charge. The addition of this compound also led to a reduction in area of voltage-dependent hysteresis evoked by long-lasting inverted triangular (downsloping and upsloping) ramp pulse. Neither the amplitude of M-type nor erg-mediated K+ current was altered by its presence. In whole-cell potential recordings, addition of PFD reduced the firing frequency, and this effect was accompanied by the depression in the amplitude of sag voltage elicited by hyperpolarizing current stimulus. Overall, this study highlights evidence that PFD is capable of perturbing specific ionic currents, revealing a potential additional impact on functional activities of different excitable cells.
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Affiliation(s)
- Wei-Ting Chang
- Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan, 70101, Taiwan; Division of Cardiology, Internal Medicine, Chi-Mei Medical Center, Tainan, 71004, Taiwan; Department of Biotechnology, Southern Taiwan University of Science and Technology, Tainan, 71004, Taiwan.
| | - Eugenio Ragazzi
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, 35131, Padova, Italy
| | - Ping-Yen Liu
- Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan, 70101, Taiwan; Division of Cardiology, Internal Medicine, College of Medicine, National Cheng Kung University Hospital, Tainan, 70401, Taiwan.
| | - Sheng-Nan Wu
- Institute of Basic Medical Sciences, National Cheng Kung University Medical College, Tainan, Taiwan; Department of Physiology, National Cheng Kung University Medical College, Tainan, Taiwan; Department of Medical Research, China Medical University Hospital, China Medical University, Taichung, Taiwan.
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Hunziker M, O'Donnell AM, Gosemann J, Alvarez LA, Puri P. Altered anoctamin-1 and tyrosine phosphorylation in congenital ureteropelvic junction obstruction. J Pediatr Surg 2020; 55:1621-1625. [PMID: 32087933 DOI: 10.1016/j.jpedsurg.2020.02.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 11/26/2019] [Accepted: 02/05/2020] [Indexed: 01/30/2023]
Abstract
PURPOSE Ureteropelvic junction (UPJ) obstruction is the most common cause of congenital hydronephrosis in children. The pathophysiology of UPJ obstruction and the exact mechanism of pelviureteral peristalsis are poorly understood. Anoctamin-1 (ANO1), a Ca2+-activated chloride channel, has been shown to play a key role in muscle wall contractions in the gastrointestinal tract. We designed this study to investigate the hypothesis that ANO1 is expressed in smooth muscle cells (SMCs) of the human UPJ and that tyrosine phosphorylation is altered in UPJ obstruction. MATERIALS AND METHODS Fresh frozen specimens of UPJ obstruction (n = 28) and control specimens from patients who underwent Wilms' tumor nephrectomy (n = 20) were prepared. Western blot (WB) was performed to evaluate levels of ANO1 protein expression and changes in tyrosine phosphorylation. In addition analysis of ANO1 and phalloidin using confocal-immunofluoresence-double staining and 3D reconstruction were carried out. RESULTS Our WB results revealed increased tyrosine phosphorylation in UPJ obstruction samples compared to controls, and decreased ANO1 expression in UPJ obstruction. Confocal microscopy showed that ANO1 immunoreactivity was decreased in SMCs of UPJ obstruction compared to controls. CONCLUSIONS We provide evidence, for the first time, of the presence of ANO1 expression in the human UPJ. We speculate that altered tyrosine phosphorylation, observed in UPJ obstruction, may lead to a failure of transmission of peristaltic waves in UPJ obstruction by inhibiting Ca2+-activated chloride channels in SMCs.
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Affiliation(s)
- Manuela Hunziker
- National Children's Research Centre, Our Lady's Children's Hospital, Dublin, Ireland; School of Medicine and Medical Science and Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Ireland
| | - Anne-Marie O'Donnell
- National Children's Research Centre, Our Lady's Children's Hospital, Dublin, Ireland
| | - Jan Gosemann
- National Children's Research Centre, Our Lady's Children's Hospital, Dublin, Ireland
| | - Luis A Alvarez
- National Children's Research Centre, Our Lady's Children's Hospital, Dublin, Ireland
| | - Prem Puri
- National Children's Research Centre, Our Lady's Children's Hospital, Dublin, Ireland; School of Medicine and Medical Science and Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Ireland.
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Sánchez-Solano A, Corral N, Segura-Covarrubias G, Guzmán-Hernández ML, Arechiga-Figueroa I, Cruz-Rangel S, Pérez-Cornejo P, Arreola J. Regulation of the Ca 2+-activated chloride channel Anoctamin-1 (TMEM16A) by Ca 2+-induced interaction with FKBP12 and calcineurin. Cell Calcium 2020; 89:102211. [PMID: 32422433 DOI: 10.1016/j.ceca.2020.102211] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 03/30/2020] [Accepted: 04/23/2020] [Indexed: 12/26/2022]
Abstract
Chloride fluxes through the calcium-gated chloride channel Anoctamin-1 (TMEM16A) control blood pressure, secretion of saliva, mucin, insulin, and melatonin, gastrointestinal motility, sperm capacitation and motility, and pain sensation. Calcium activates a myriad of regulatory proteins but how these proteins affect TMEM16A activity is unresolved. Here we show by co-immunoprecipitation that increasing intracellular calcium with ionomycin or by activating sphingosine-1-phosphate receptors, induces coupling of calcium/calmodulin-dependent phosphatase calcineurin and prolyl isomerase FK506-binding protein 12 (FKBP12) to TMEM16A in HEK-293 cells. Application of drugs that target either calcineurin (cyclosporine A) or FKBP12 (tacrolimus known as FK506 and sirolimus known as rapamycin) caused a decrease in TMEM16A activity. In addition, FK506 and BAPTA-AM prevented co-immunoprecipitation between FKBP12 and TMEM16A. FK506 rendered the channel insensitive to cyclosporine A without altering its apparent calcium sensitivity whereas zero intracellular calcium blocked the effect of FK506. Rapamycin decreased TMEM16A activity in cells pre-treated with cyclosporine A or FK506. These results suggest the formation of a TMEM16A-FKBP12-calcineurin complex that regulates channel function. We conclude that upon a cytosolic calcium increase the TMEM16A-FKPB12-calcineurin trimers are assembled. Such hetero-oligomerization enhances TMEM16A channel activity but is not mandatory for activation by calcium.
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Affiliation(s)
- Alfredo Sánchez-Solano
- Physics Institute, Universidad Autónoma de San Luis Potosí, Ave. Dr. Manuel Nava #6, San Luis Potosí, SLP 78290, Mexico
| | - Nancy Corral
- Department of Physiology and Biophysics, Universidad Autónoma de San Luis Potosí School of Medicine, Ave. V. Carranza 2405, San Luis Potosí, SLP 78290, Mexico
| | - Guadalupe Segura-Covarrubias
- Physics Institute, Universidad Autónoma de San Luis Potosí, Ave. Dr. Manuel Nava #6, San Luis Potosí, SLP 78290, Mexico
| | - María Luisa Guzmán-Hernández
- Cátedra CONACYT, School of Medicine, Universidad Autónoma de San Luis Potosí, Ave. V. Carranza 2405, San Luis Potosí, SLP 78290, Mexico
| | - Ivan Arechiga-Figueroa
- Cátedra CONACYT, School of Medicine, Universidad Autónoma de San Luis Potosí, Ave. V. Carranza 2405, San Luis Potosí, SLP 78290, Mexico
| | - Silvia Cruz-Rangel
- Physics Institute, Universidad Autónoma de San Luis Potosí, Ave. Dr. Manuel Nava #6, San Luis Potosí, SLP 78290, Mexico
| | - Patricia Pérez-Cornejo
- Department of Physiology and Biophysics, Universidad Autónoma de San Luis Potosí School of Medicine, Ave. V. Carranza 2405, San Luis Potosí, SLP 78290, Mexico
| | - Jorge Arreola
- Physics Institute, Universidad Autónoma de San Luis Potosí, Ave. Dr. Manuel Nava #6, San Luis Potosí, SLP 78290, Mexico.
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12
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Ayon RJ, Hawn MB, Aoun J, Wiwchar M, Forrest AS, Cunningham F, Singer CA, Valencik ML, Greenwood IA, Leblanc N. Molecular mechanism of TMEM16A regulation: role of CaMKII and PP1/PP2A. Am J Physiol Cell Physiol 2019; 317:C1093-C1106. [PMID: 31461344 DOI: 10.1152/ajpcell.00059.2018] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
This study explored the mechanism by which Ca2+-activated Cl- channels (CaCCs) encoded by the Tmem16a gene are regulated by calmodulin-dependent protein kinase II (CaMKII) and protein phosphatases 1 (PP1) and 2A (PP2A). Ca2+-activated Cl- currents (IClCa) were recorded from HEK-293 cells expressing mouse TMEM16A. IClCa were evoked using a pipette solution in which free Ca2+ concentration was clamped to 500 nM, in the presence (5 mM) or absence of ATP. With 5 mM ATP, IClCa decayed to <50% of the initial current magnitude within 10 min after seal rupture. IClCa rundown seen with ATP-containing pipette solution was greatly diminished by omitting ATP. IClCa recorded after 20 min of cell dialysis with 0 ATP were more than twofold larger than those recorded with 5 mM ATP. Intracellular application of autocamtide-2-related inhibitory peptide (5 µM) or KN-93 (10 µM), two specific CaMKII inhibitors, produced a similar attenuation of TMEM16A rundown. In contrast, internal application of okadaic acid (30 nM) or cantharidin (100 nM), two nonselective PP1 and PP2A blockers, promoted the rundown of TMEM16A in cells dialyzed with 0 ATP. Mutating serine 528 of TMEM16A to an alanine led to a similar inhibition of TMEM16A rundown to that exerted by either one of the two CaMKII inhibitors tested, which was not observed for three putative CaMKII consensus sites for phosphorylation (T273, T622, and S730). Our results suggest that TMEM16A-mediated CaCCs are regulated by CaMKII and PP1/PP2A. Our data also suggest that serine 528 of TMEM16A is an important contributor to the regulation of IClCa by CaMKII.
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Affiliation(s)
- Ramon J Ayon
- Division of Translational and Regenerative Medicine, Department of Medicine, College of Medicine, The University of Arizona College of Medicine, Arizona Health Sciences Center, Tucson, Arizona
| | - Matthew B Hawn
- Department of Pharmacology, Center of Biomedical Research Excellence for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, Reno, Nevada.,The Center for Cardiovascular Research, Center of Biomedical Research Excellence for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Joydeep Aoun
- Department of Pharmacology, Center of Biomedical Research Excellence for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, Reno, Nevada.,The Center for Cardiovascular Research, Center of Biomedical Research Excellence for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Michael Wiwchar
- Department of Pharmacology, Center of Biomedical Research Excellence for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Abigail S Forrest
- Department of Pharmacology, Center of Biomedical Research Excellence for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Fiona Cunningham
- Department of Pharmacology, Center of Biomedical Research Excellence for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Cherie A Singer
- Department of Pharmacology, Center of Biomedical Research Excellence for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Maria L Valencik
- Department of Pharmacology, Center of Biomedical Research Excellence for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Iain A Greenwood
- Institute of Molecular and Clinical Sciences, St. George's University of London, London, United Kingdom
| | - Normand Leblanc
- Department of Pharmacology, Center of Biomedical Research Excellence for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, Reno, Nevada.,The Center for Cardiovascular Research, Center of Biomedical Research Excellence for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, Reno, Nevada
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13
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Askew Page HR, Dalsgaard T, Baldwin SN, Jepps TA, Povstyan O, Olesen SP, Greenwood IA. TMEM16A is implicated in the regulation of coronary flow and is altered in hypertension. Br J Pharmacol 2019; 176:1635-1648. [PMID: 30710335 DOI: 10.1111/bph.14598] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 12/19/2018] [Accepted: 01/05/2019] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND AND PURPOSE Coronary artery disease leads to ischaemic heart disease and ultimately myocardial infarction. Thus, it is important to determine the factors that regulate coronary blood flow. Ca2+ -activated chloride channels contribute to the regulation of arterial tone; however, their role in coronary arteries is unknown. The aim of this study was to investigate the expression and function of the main molecular correlate of Ca2+ -activated chloride channels, TMEM16A, in rat coronary arteries. EXPERIMENTAL APPROACH We performed mRNA and protein analysis, electrophysiological studies of coronary artery myocytes, and functional studies of coronary artery contractility and coronary perfusion, using novel inhibitors of TMEM16A. Furthermore, we assessed whether any changes in expression and function occurred in coronary arteries from spontaneously hypertensive rats (SHRs). KEY RESULTS TMEM16A was expressed in rat coronary arteries. The TMEM16A-specific inhibitor, MONNA, hyperpolarised the membrane potential in U46619. MONNA, T16Ainh -A01, and Ani9 attenuated 5-HT/U46619-induced contractions. MONNA and T16Ainh -A01 also increased coronary flow in Langendorff perfused rat heart preparations. TMEM16A mRNA was increased in coronary artery smooth muscle cells from SHRs, and U46619 and 5-HT were more potent in arteries from SHRs than in those from normal Wistar rats. MONNA diminished this increased sensitivity to U46619 and 5-HT. CONCLUSIONS AND IMPLICATIONS In conclusion, TMEM16A is a key regulator of coronary blood flow and is implicated in the altered contractility of coronary arteries from SHRs.
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Affiliation(s)
- Henry R Askew Page
- Vascular Biology Research Centre, Institute of Molecular and Clinical Sciences, St George's University of London, London, UK.,Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Thomas Dalsgaard
- Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Samuel N Baldwin
- Vascular Biology Research Centre, Institute of Molecular and Clinical Sciences, St George's University of London, London, UK
| | - Thomas A Jepps
- Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Oleksandr Povstyan
- Vascular Biology Research Centre, Institute of Molecular and Clinical Sciences, St George's University of London, London, UK
| | - Søren P Olesen
- Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Iain A Greenwood
- Vascular Biology Research Centre, Institute of Molecular and Clinical Sciences, St George's University of London, London, UK.,Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
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14
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Dayal A, Ng SFJ, Grabner M. Ca 2+-activated Cl - channel TMEM16A/ANO1 identified in zebrafish skeletal muscle is crucial for action potential acceleration. Nat Commun 2019; 10:115. [PMID: 30631052 PMCID: PMC6328546 DOI: 10.1038/s41467-018-07918-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 12/03/2018] [Indexed: 01/16/2023] Open
Abstract
The Ca2+-activated Cl− channel (CaCC) TMEM16A/Anoctamin 1 (ANO1) is expressed in gastrointestinal epithelia and smooth muscle cells where it mediates secretion and intestinal motility. However, ANO1 Cl− conductance has never been reported to play a role in skeletal muscle. Here we show that ANO1 is robustly expressed in the highly evolved skeletal musculature of the euteleost species zebrafish. We characterised ANO1 as bonafide CaCC which is activated close to maximum by Ca2+ ions released from the SR during excitation-contraction (EC) coupling. Consequently, our study addressed the question about the physiological advantage of implementation of ANO1 into the euteleost skeletal-muscle EC coupling machinery. Our results reveal that Cl− influx through ANO1 plays an essential role in restricting the width of skeletal-muscle action potentials (APs) by accelerating the repolarisation phase. Resulting slimmer APs enable higher AP-frequencies and apparently tighter controlled, faster and stronger muscle contractions, crucial for high speed movements. The Ca2+-activated Cl- channel TMEM16A/Anoctamin 1 (ANO1) mediates secretion and intestinal motility in gastrointestinal epithelia and smooth muscle cells. Here, the authors show a role for ANO1 in zebrafish skeletal muscle which is activated by SR Ca2+ release during excitation-contraction coupling.
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Affiliation(s)
- Anamika Dayal
- Department of Medical Genetics, Molecular and Clinical Pharmacology, Division of Biochemical Pharmacology, Medical University of Innsbruck, Peter Mayr Strasse 1, A-6020, Innsbruck, Austria.
| | - Shu Fun J Ng
- Department of Medical Genetics, Molecular and Clinical Pharmacology, Division of Biochemical Pharmacology, Medical University of Innsbruck, Peter Mayr Strasse 1, A-6020, Innsbruck, Austria
| | - Manfred Grabner
- Department of Medical Genetics, Molecular and Clinical Pharmacology, Division of Biochemical Pharmacology, Medical University of Innsbruck, Peter Mayr Strasse 1, A-6020, Innsbruck, Austria.
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15
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Ji Q, Guo S, Wang X, Pang C, Zhan Y, Chen Y, An H. Recent advances in TMEM16A: Structure, function, and disease. J Cell Physiol 2018; 234:7856-7873. [PMID: 30515811 DOI: 10.1002/jcp.27865] [Citation(s) in RCA: 86] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Accepted: 11/13/2018] [Indexed: 12/13/2022]
Abstract
TMEM16A (also known as anoctamin 1, ANO1) is the molecular basis of the calcium-activated chloride channels, with ten transmembrane segments. Recently, atomic structures of the transmembrane domains of mouse TMEM16A (mTMEM16A) were determined by single-particle electron cryomicroscopy. This gives us a solid ground to discuss the electrophysiological properties and functions of TMEM16A. TMEM16A is reported to be dually regulated by Ca2+ and voltage. In addition, the dysfunction of TMEM16A has been found to be involved in many diseases including cystic fibrosis, various cancers, hypertension, and gastrointestinal motility disorders. TMEM16A is overexpressed in many cancers, including gastrointestinal stromal tumors, gastric cancer, head and neck squamous cell carcinoma (HNSCC), colon cancer, pancreatic ductal adenocarcinoma, and esophageal cancer. Furthermore, overexpression of TMEM16A is related to the occurrence, proliferation, and migration of tumor cells. To date, several studies have shown that many natural compounds and synthetic compounds have regulatory effects on TMEM16A. These small molecule compounds might be novel drugs for the treatment of diseases caused by TMEM16A dysfunction in the future. In addition, recent studies have shown that TMEM16A plays different roles in different diseases through different signal transduction pathways. This review discusses the topology, electrophysiological properties, modulators and functions of TMEM16A in mediates nociception, gastrointestinal dysfunction, hypertension, and cancer and focuses on multiple regulatory mechanisms regarding TMEM16A.
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Affiliation(s)
- Qiushuang Ji
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China
| | - Shuai Guo
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China
| | - Xuzhao Wang
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China
| | - Chunli Pang
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China
| | - Yong Zhan
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China
| | - Yafei Chen
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China
| | - Hailong An
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China
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16
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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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17
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Boedtkjer E, Matchkov VV, Boedtkjer DMB, Aalkjaer C. Negative News: Cl− and HCO3− in the Vascular Wall. Physiology (Bethesda) 2016; 31:370-83. [DOI: 10.1152/physiol.00001.2016] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Cl− and HCO3− are the most prevalent membrane-permeable anions in the intra- and extracellular spaces of the vascular wall. Outwardly directed electrochemical gradients for Cl− and HCO3− permit anion channel opening to depolarize vascular smooth muscle and endothelial cells. Transporters and channels for Cl− and HCO3− also modify vascular contractility and structure independently of membrane potential. Transport of HCO3− regulates intracellular pH and thereby modifies the activity of enzymes, ion channels, and receptors. There is also evidence that Cl− and HCO3− transport proteins affect gene expression and protein trafficking. Considering the extensive implications of Cl− and HCO3− in the vascular wall, it is critical to understand how these ions are transported under physiological conditions and how disturbances in their transport can contribute to disease development. Recently, sensing mechanisms for Cl− and HCO3− have been identified in the vascular wall where they modify ion transport and vasomotor function, for instance, during metabolic disturbances. This review discusses current evidence that transport (e.g., via NKCC1, NBCn1, Ca2+-activated Cl− channels, volume-regulated anion channels, and CFTR) and sensing (e.g., via WNK and RPTPγ) of Cl− and HCO3− influence cardiovascular health and disease.
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Affiliation(s)
| | | | - Donna M. B. Boedtkjer
- Department of Biomedicine, Aarhus University, Denmark
- Department of Clinical Medicine, Aarhus University, Denmark; and
| | - Christian Aalkjaer
- Department of Biomedicine, Aarhus University, Denmark
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
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18
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Toussaint F, Charbel C, Allen BG, Ledoux J. Vascular CaMKII: heart and brain in your arteries. Am J Physiol Cell Physiol 2016; 311:C462-78. [PMID: 27306369 DOI: 10.1152/ajpcell.00341.2015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 06/14/2016] [Indexed: 01/02/2023]
Abstract
First characterized in neuronal tissues, the multifunctional calcium/calmodulin-dependent protein kinase II (CaMKII) is a key signaling component in several mammalian biological systems. Its unique capacity to integrate various Ca(2+) signals into different specific outcomes is a precious asset to excitable and nonexcitable cells. Numerous studies have reported roles and mechanisms involving CaMKII in brain and heart tissues. However, corresponding functions in vascular cell types (endothelium and vascular smooth muscle cells) remained largely unexplored until recently. Investigation of the intracellular Ca(2+) dynamics, their impact on vascular cell function, the regulatory processes involved and more recently the spatially restricted oscillatory Ca(2+) signals and microdomains triggered significant interest towards proteins like CaMKII. Heteromultimerization of CaMKII isoforms (four isoforms and several splice variants) expands this kinase's peculiar capacity to decipher Ca(2+) signals and initiate specific signaling processes, and thus controlling cellular functions. The physiological functions that rely on CaMKII are unsurprisingly diverse, ranging from regulating contractile state and cellular proliferation to Ca(2+) homeostasis and cellular permeability. This review will focus on emerging evidence of CaMKII as an essential component of the vascular system, with a focus on the kinase isoform/splice variants and cellular system studied.
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Affiliation(s)
- Fanny Toussaint
- Research Center, Montreal Heart Institute, Montreal, Quebec, Canada; Department of Molecular and Integrative Physiology, Université de Montréal, Montreal Quebec, Canada
| | - Chimène Charbel
- Research Center, Montreal Heart Institute, Montreal, Quebec, Canada; Department of Pharmacology, Université de Montréal, Montreal Quebec, Canada
| | - Bruce G Allen
- Research Center, Montreal Heart Institute, Montreal, Quebec, Canada; Department of Medicine, Université de Montréal, Montreal Quebec, Canada; and Department of Biochemistry and Molecular Medicine, Université de Montréal, Montreal Quebec, Canada
| | - Jonathan Ledoux
- Research Center, Montreal Heart Institute, Montreal, Quebec, Canada; Department of Medicine, Université de Montréal, Montreal Quebec, Canada; and
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19
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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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20
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Toussaint F, Charbel C, Blanchette A, Ledoux J. CaMKII regulates intracellular Ca²⁺ dynamics in native endothelial cells. Cell Calcium 2015; 58:275-85. [PMID: 26100947 DOI: 10.1016/j.ceca.2015.06.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2014] [Revised: 05/15/2015] [Accepted: 06/06/2015] [Indexed: 01/11/2023]
Abstract
Localized endothelial Ca(2+) signalling, such as Ca(2+) pulsars, can modulate the contractile state of the underlying vascular smooth muscle cell through specific endothelial targets. In addition to K(Ca)3.1 as a target, Ca(2+) pulsars, an IP3R-dependent pulsatile Ca(2+) release from the endoplasmic reticulum (ER) could activate a frequency-sensitive Ca(2+)-dependent kinase such as CaMKII. In the absence of extracellular Ca(2+), acetylcholine increased endothelial CaMKII phosphorylation and activation, thereby suggesting CaMKII activation independently of Ca(2+) influx. Herein, a reciprocal relation where CaMKII controls endothelial Ca(2+) dynamics has been investigated in mesenteric arteries. Both CaMKIIα and β isoforms have been identified in endothelial cells and close proximity (<40 nm) suggests their association in heteromultimers. Intracellular Ca(2+) monitoring with high speed confocal microscopy then showed that inhibition of CaMKII with KN-93 significantly increased the population of Ca(2+) pulsars active sites (+89%), suggesting CaMKII as a major regulator of Ca(2+) pulsars in native endothelium. Mechanistic insights were then sought through the elucidation of the impact of CaMKII on ER Ca(2+) store. ER Ca(2+) emptying was accelerated by CaMKII inhibition and ER Ca(2+) content was assessed using ionomycin. Exposure to KN-93 strongly diminished ER Ca(2+) content (-61%) by relieving CaMKII-dependent inhibition of IP3 receptors (IP3R). Moreover, in situ proximity ligation assay suggested CaMKII-IP3R promiscuity, essential condition for a protein-protein interaction. Interestingly, segregation of IP3R within myoendothelial projection (MEP) appears to be isoform-specific. Hence, only IP3R type 1 and type 2 are detected within fenestrations of the internal elastic lamina, sites of MEP, whilst type 3 is absent from these structures. In summary, CaMKII seems to act as a Ca(2+)-sensitive switch of a negative feedback loop regulating endothelial Ca(2+) homeostasis, including Ca(2+) pulsars.
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Affiliation(s)
- Fanny Toussaint
- Research Center, Montreal Heart Institute, Montréal, Québec, Canada; Department of Physiology, Université de Montréal, Québec, Canada
| | - Chimène Charbel
- Research Center, Montreal Heart Institute, Montréal, Québec, Canada; Department of Pharmacology, Université de Montréal, Québec, Canada
| | | | - Jonathan Ledoux
- Research Center, Montreal Heart Institute, Montréal, Québec, Canada; Department of Physiology, Université de Montréal, Québec, Canada; Department of Pharmacology, Université de Montréal, Québec, Canada; Department of Medicine, Université de Montréal, Québec, Canada.
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21
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Pritchard HAT, Leblanc N, Albert AP, Greenwood IA. Inhibitory role of phosphatidylinositol 4,5-bisphosphate on TMEM16A-encoded calcium-activated chloride channels in rat pulmonary artery. Br J Pharmacol 2015; 171:4311-21. [PMID: 24834965 DOI: 10.1111/bph.12778] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Revised: 04/22/2014] [Accepted: 05/07/2014] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND AND PURPOSE Calcium-activated chloride channels (CaCCs) are key depolarizing mechanisms that have an important role in vascular smooth muscle contraction. Here, we investigated whether these channels are regulated by phosphatidylinositol (4,5) bisphosphate [P(4,5)P2 ], a known regulator of various ion channels. EXPERIMENTAL APPROACH Calcium-activated Cl(-) currents (IClCa ) were recorded by patch clamp electrophysiology of rat isolated pulmonary artery smooth muscle cells. TMEM16A protein-phosphoinositide interaction was studied by co-immunoprecipitation and phosphoinositide binding arrays on protein lysates from whole pulmonary arteries and HEK293 cells overexpressing TMEM16A, the molecular correlate. KEY RESULTS PI(4,5)P2 and other phospholipids were shown to bind directly to TMEM16A isolated from whole pulmonary artery (PA) and TMEM16A-eGFP expressed in HEK293 cells. Agents that reduced PI(4,5)P2 levels through different routes [PLC activation, PI4K inhibition, PI(4,5)P2 scavenging and absorption] all increased IClCa evoked by solutions containing clamped-free [Ca(2+) ], whereas enrichment of activating solutions with PI(4,5)P2 inhibited IClca in PA smooth muscle cells with approximately 50% reduction at 1 μM. CONCLUSIONS AND IMPLICATIONS These data are the first to show a negative regulation of TMEM16A-encoded CaCCs by PI(4,5)P2 and propose that control of PI(4,5)P2 levels is a key determinant of arterial physiology.
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Affiliation(s)
- H A T Pritchard
- Vascular Biology Research Centre, Institute of Cardiovascular and Cell Sciences, St George's, University of London, London, UK
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22
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Hill BJF, Muldrew E. Oestrogen upregulates the sarcoplasmic reticulum Ca(2+) ATPase pump in coronary arteries. Clin Exp Pharmacol Physiol 2015; 41:430-6. [PMID: 24684418 DOI: 10.1111/1440-1681.12233] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Revised: 03/20/2014] [Accepted: 03/25/2014] [Indexed: 12/30/2022]
Abstract
The presence of circulating plasma 17β-oestradiol (E2) is beneficial in women against abnormal vascular tone development, such as coronary arterial vasospasms. Several vascular diseases have demonstrated that increased expression of the sarcoplasmic reticulum Ca(2+) -ATPase pump (SERCA2b) serves to limit the excessive accumulation of intracellular Ca(2+) . Therefore, the hypothesis of the present study was that E2 would increase SERCA2b expression in the coronary vasculature. Coronary arteries were dissected from hearts obtained from mature female pigs. Artery segments were cultured for 24 h in E2 (1 pmol/L or 1 nmol/L) and homogenized for western blot analysis. At 1 nmol/L, E2 induced an approximate 50% increase in immunoreactivity for SERCA2b. In addition, E2 increased the protein expression of the known SERCA regulatory proteins, protein kinase A (PKA) and protein kinase G (PKG). The E2-induced increase in SERCA2b was attenuated when the culture medium was supplemented with the oestrogen receptor (ER) α/β antagonist ICI 182,780 and the PKG antagonist KT5823 (10 μmol/L, 24 h for both). The PKA antagonist (KT5720; 10 μmol/L, 24 h) had no effect on SERCA2b expression. Removal of the endothelium (using a wooden toothpick) from artery segments prior to culture decreased the E2-mediated increase in SERCA2b and PKG expression by 45% and 47%, respectively. Overall, the findings suggest that one of the potential cardiovascular benefits of E2 in women is upregulation of SERCA2b, via activation of the classic ERα and ERβ pathway.
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Affiliation(s)
- Brent J F Hill
- Department of Biology, University of Central Arkansas, Conway, AR, USA
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23
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Abstract
TMEM16 proteins, also known as anoctamins, are involved in a variety of functions that include ion transport, phospholipid scrambling, and regulation of other membrane proteins. The first two members of the family, TMEM16A (anoctamin-1, ANO1) and TMEM16B (anoctamin-2, ANO2), function as Ca2+-activated Cl- channels (CaCCs), a type of ion channel that plays important functions such as transepithelial ion transport, smooth muscle contraction, olfaction, phototransduction, nociception, and control of neuronal excitability. Genetic ablation of TMEM16A in mice causes impairment of epithelial Cl- secretion, tracheal abnormalities, and block of gastrointestinal peristalsis. TMEM16A is directly regulated by cytosolic Ca2+ as well as indirectly by its interaction with calmodulin. Other members of the anoctamin family, such as TMEM16C, TMEM16D, TMEM16F, TMEM16G, and TMEM16J, may work as phospholipid scramblases and/or ion channels. In particular, TMEM16F (ANO6) is a major contributor to the process of phosphatidylserine translocation from the inner to the outer leaflet of the plasma membrane. Intriguingly, TMEM16F is also associated with the appearance of anion/cation channels activated by very high Ca2+ concentrations. Furthermore, a TMEM16 protein expressed in Aspergillus fumigatus displays both ion channel and lipid scramblase activity. This finding suggests that dual function is an ancestral characteristic of TMEM16 proteins and that some members, such as TMEM16A and TMEM16B, have evolved to a pure channel function. Mutations in anoctamin genes (ANO3, ANO5, ANO6, and ANO10) cause various genetic diseases. These diseases suggest the involvement of anoctamins in a variety of cell functions whose link with ion transport and/or lipid scrambling needs to be clarified.
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Abstract
Ca(2+)-activated Cl(-) channels (CaCCs) are plasma membrane proteins involved in various important physiological processes. In epithelial cells, CaCC activity mediates the secretion of Cl(-) and of other anions, such as bicarbonate and thiocyanate. In smooth muscle and excitable cells of the nervous system, CaCCs have an excitatory role coupling intracellular Ca(2+) elevation to membrane depolarization. Recent studies indicate that TMEM16A (transmembrane protein 16 A or anoctamin 1) and TMEM16B (transmembrane protein 16 B or anoctamin 2) are CaCC-forming proteins. Induced expression of TMEM16A and B in null cells by transfection causes the appearance of Ca(2+)-activated Cl(-) currents similar to those described in native tissues. Furthermore, silencing of TMEM16A by RNAi causes disappearance of CaCC activity in cells from airway epithelium, biliary ducts, salivary glands, and blood vessel smooth muscle. Mice devoid of TMEM16A expression have impaired Ca(2+)-dependent Cl(-) secretion in the epithelial cells of the airways, intestine, and salivary glands. These animals also show a loss of gastrointestinal motility, a finding consistent with an important function of TMEM16A in the electrical activity of gut pacemaker cells, that is, the interstitial cells of Cajal. Identification of TMEM16 proteins will help to elucidate the molecular basis of Cl(-) transport.
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Affiliation(s)
- Loretta Ferrera
- Laboratory of Molecular Genetics, Istituto Giannina Gaslini, Genova, Italy
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25
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Davis AJ, Shi J, Pritchard HAT, Chadha PS, Leblanc N, Vasilikostas G, Yao Z, Verkman AS, Albert AP, Greenwood IA. Potent vasorelaxant activity of the TMEM16A inhibitor T16A(inh) -A01. Br J Pharmacol 2013; 168:773-84. [PMID: 22946562 DOI: 10.1111/j.1476-5381.2012.02199.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Revised: 07/25/2012] [Accepted: 08/15/2012] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND AND PURPOSE T16A(inh) -A01 is a recently identified inhibitor of the calcium-activated chloride channel TMEM16A. The aim of this study was to test the efficacy of T16A(inh) -A01 for inhibition of calcium-activated chloride channels in vascular smooth muscle and consequent effects on vascular tone. EXPERIMENTAL APPROACH Single channel and whole cell patch clamp was performed on single smooth muscle cells from rabbit pulmonary artery and mouse thoracic aorta. Isometric tension studies were performed on mouse thoracic aorta and mesenteric artery as well as human abdominal visceral adipose artery. KEY RESULTS In rabbit pulmonary artery myocytes T16A(inh) -A01 (1-30 μM) inhibited single calcium (Ca(2+) )-activated chloride (Cl(-) ) channels and whole cell currents activated by 500 nM free Ca(2+) . Similar effects were observed for single Ca(2+) -activated Cl(-) channels in mouse thoracic aorta, and in both cell types, channel activity was abolished by two antisera raised against TMEM16A but not by a bestrophin antibody. The TMEM16A potentiator, F(act) (10 μM), increased single channel and whole cell Ca(2+) -activated Cl(-) currents in rabbit pulmonary arteries. In isometric tension studies, T16A(inh) -A01 relaxed mouse thoracic aorta pre-contracted with methoxamine with an IC(50) of 1.6 μM and suppressed the methoxamine concentration-effect curve. T16A(inh) -A01 did not affect the maximal contraction produced by 60 mM KCl and the relaxant effect of 10 μM T16A(inh) -A01 was not altered by incubation of mouse thoracic aorta in a cocktail of potassium (K(+) ) channel blockers. T16A(inh) -A01 (10 μM) also relaxed human visceral adipose arteries by 88 ± 3%. CONCLUSIONS AND IMPLICATIONS T16A(inh) -A01 blocks calcium-activated chloride channels in vascular smooth muscle cells and relaxes murine and human blood vessels.
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Affiliation(s)
- Alison J Davis
- Pharmacology and Cell Physiology Research Group, Division of Biomedical Sciences, St George's, University of London, London, UK
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Donaldson SH, Galietta L. New pulmonary therapies directed at targets other than CFTR. Cold Spring Harb Perspect Med 2013; 3:3/6/a009787. [PMID: 23732851 DOI: 10.1101/cshperspect.a009787] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Our current understanding of the pathogenesis of cystic fibrosis (CF) lung disease stresses the importance of the physical and chemical properties of the airway surface liquid (ASL). In particular, the loss of cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel function in CF reduces the volume and fluidity of the ASL, thus impairing mucociliary clearance and innate antimicrobial mechanisms. Besides direct approaches to restoring mutant CFTR function, alternative therapeutic strategies may also be considered to correct the basic defect of impaired salt and water transport. Such alternative strategies are focused on the restoration of mucociliary transport by (1) reducing sodium and fluid absorption by inhibiting the ENaC channel; (2) activating alternative chloride channels; and (3) increasing airway surface hydration with osmotic agents. Therapeutic approaches directed at targets other than CFTR are attractive because they are potentially useful to all patients irrespective of their genotype. Clinical trials are underway to test the efficacy of these approaches.
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Affiliation(s)
- Scott H Donaldson
- Cystic Fibrosis Research and Treatment Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA.
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27
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Ganapathi SB, Wei SG, Zaremba A, Lamb FS, Shears SB. Functional regulation of ClC-3 in the migration of vascular smooth muscle cells. Hypertension 2013; 61:174-9. [PMID: 23150504 PMCID: PMC3521842 DOI: 10.1161/hypertensionaha.112.194209] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Accepted: 10/22/2012] [Indexed: 12/17/2022]
Abstract
Migration of vascular smooth muscle cells (VSMCs) into neointima contributes to atherosclerosis and restenosis. This migration requires coordinated plasmalemmal fluxes of water and ions. Here, we show that aortic VSMC migration depends on the regulation of transmembrane Cl(-) flux by ClC-3, a Cl(-) channel/transporter. The contribution of ClC-3 to plasmalemmal Cl(-) current was studied in VSMCs by electrophysiological recordings. Cl(-) current was negligible in cells perfused with 0 [Ca(2+)]. Raising intracellular [Ca(2+)] to 0.5 μM activated a Cl(-) current (I(Cl.Ca)), approximately half of which was eliminated on inhibition by KN-93 of calmodulin-dependent protein kinase II. I(Cl.Ca) was also halved by inositol-3,4,5,6-tetrakisphosphate, a cellular signal with the biological function of specifically preventing calmodulin-dependent protein kinase II from activating I(Cl.Ca). Gene disruption of ClC-3 reduced I(Cl.Ca) by 50%. Moreover, I(Cl.Ca) in the ClC-3 null VSMCs was not affected by either KN-93 or inositol-3,4,5,6-tetrakisphosphate. We conclude that I(Cl.Ca) is composed of 2 components, one is ClC-3 independent whereas the other is ClC-3 dependent, activated by calmodulin-dependent protein kinase II and inhibited by inositol-3,4,5,6-tetrakisphosphate. We also assayed VSMC migration in transwell assays. Migration was halved in ClC-3 null cells versus wild-type cells. In addition, inhibition of ClC-3 by niflumic acid, KN-93, or inositol-3,4,5,6-tetrakisphosphate each reduced cell migration in wild-type cells but not in ClC-3 null cells. These cell-signaling roles of ClC-3 in VSMC migration suggest new therapeutic approaches to vascular remodeling diseases.
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MESH Headings
- Animals
- Aorta/cytology
- Aorta/drug effects
- Aorta/metabolism
- Benzylamines/pharmacology
- Calcium-Calmodulin-Dependent Protein Kinase Type 2/antagonists & inhibitors
- Cell Movement/drug effects
- Cell Movement/physiology
- Cells, Cultured
- Chloride Channels/genetics
- Chloride Channels/metabolism
- Inositol Phosphates/pharmacology
- Mice
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Myocytes, Smooth Muscle/cytology
- Myocytes, Smooth Muscle/drug effects
- Myocytes, Smooth Muscle/metabolism
- Niflumic Acid/pharmacology
- Protein Kinase Inhibitors/pharmacology
- Signal Transduction/drug effects
- Signal Transduction/physiology
- Sulfonamides/pharmacology
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Affiliation(s)
- Sindura B. Ganapathi
- Inositol Signaling Group, Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, PO Box 12233, NC 27709, USA
| | - Shun-Guang Wei
- Inositol Signaling Group, Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, PO Box 12233, NC 27709, USA
| | - Angelika Zaremba
- Inositol Signaling Group, Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, PO Box 12233, NC 27709, USA
| | - Fred S. Lamb
- Department of Pediatrics, University of Iowa Children’s Hospital, Iowa City, Iowa 52242, USA
| | - Stephen B. Shears
- Inositol Signaling Group, Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, PO Box 12233, NC 27709, USA
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28
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Zhang CH, Li Y, Zhao W, Lifshitz LM, Li H, Harfe BD, Zhu MS, ZhuGe R. The transmembrane protein 16A Ca(2+)-activated Cl- channel in airway smooth muscle contributes to airway hyperresponsiveness. Am J Respir Crit Care Med 2012; 187:374-81. [PMID: 23239156 DOI: 10.1164/rccm.201207-1303oc] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
RATIONALE Asthma is a chronic inflammatory disorder with a characteristic of airway hyperresponsiveness (AHR). Ca(2+)-activated Cl(-) [Cl((Ca))] channels are inferred to be involved in AHR, yet their molecular nature and the cell type they act within to mediate this response remain unknown. OBJECTIVES Transmembrane protein 16A (TMEM16A) and TMEM16B are Cl((Ca)) channels, and activation of Cl((Ca)) channels in airway smooth muscle (ASM) contributes to agonist-induced airway contraction. We hypothesized that Tmem16a and/or Tmem16b encode Cl((Ca)) channels in ASM and mediate AHR. METHODS We assessed the expression of the TMEM16 family, and the effects of niflumic acid and benzbromarone on AHR and airway contraction, in an ovalbumin-sensitized mouse model of chronic asthma. We also cloned TMEM16A from ASM and examined the Cl(-) currents it produced in HEK293 cells. We further studied the impacts of TMEM16A deletion on Ca(2+) agonist-induced cell shortening, and on Cl((Ca)) currents activated by Ca(2+) sparks (localized, short-lived Ca(2+) transients due to the opening of ryanodine receptors) in mouse ASM cells. MEASUREMENTS AND MAIN RESULTS TMEM16A, but not TMEM16B, is expressed in ASM cells and its expression in these cells is up-regulated in ovalbumin-sensitized mice. Niflumic acid and benzbromarone prevent AHR and contraction evoked by methacholine in ovalbumin-sensitized mice. TMEM16A produces Cl((Ca)) currents with kinetics similar to native Cl((Ca)) currents. TMEM16A deletion renders Ca(2+) sparks unable to activate Cl((Ca)) currents, and weakens caffeine- and methacholine-induced cell shortening. CONCLUSIONS Tmem16a encodes Cl((Ca)) channels in ASM and contributes to Ca(2+) agonist-induced contraction. In addition, up-regulation of TMEM16A and its augmented activation contribute to AHR in an ovalbumin-sensitized mouse model of chronic asthma. TMEM16A may represent a potential therapeutic target for asthma.
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Affiliation(s)
- Cheng-Hai Zhang
- Model Animal Research Center, Nanjing University, Nanjing, China
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29
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Tian Y, Schreiber R, Kunzelmann K. Anoctamins are a family of Ca2+-activated Cl- channels. J Cell Sci 2012; 125:4991-8. [PMID: 22946059 DOI: 10.1242/jcs.109553] [Citation(s) in RCA: 128] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Anoctamin 1 (Ano1; TMEM16A) and anoctamin 2 (Ano2; TMEM16B) are novel Cl(-) channels transiently activated by an increase in intracellular Ca(2+). These channels are essential for epithelial Cl(-) secretion, smooth muscle peristalsis and olfactory signal transduction. They are central to inherited diseases and cancer and can act as heat sensors. Surprisingly, another member of this protein family, Ano6, operates as a Ca(2+)-activated phospholipid scramblase, and others were reported as intracellular proteins. It is therefore unclear whether anoctamins constitute a family of Ca(2+)-activated Cl(-) channels, or are proteins with heterogeneous functions. Using whole-cell patch clamping we demonstrate that Ano4-10 are all able to produce transient Ca(2+)-activated Cl(-) currents when expressed in HEK293 cells. Although some anoctamins (Ano1, 2, 4, 6, 7) were found to be well expressed in the plasma membrane, others (Ano8, 9, 10) show rather poor membrane expression and were mostly retained in the cytosol. The transient nature of the Cl(-) currents was demonstrated to be independent of intracellular Ca(2+) levels. We show that inactivation of Ano1 currents occurs in the continuous presence of elevated Ca(2+) concentrations, possibly by calmodulin-dependent kinase. The present results demonstrate that anoctamins are a family of Ca(2+)-activated Cl(-) channels, which also induce permeability for cations. They may operate as Cl(-) channels located in the plasma membrane or in intracellular compartments. These results increase our understanding of the physiological significance of anoctamins and their role in disease.
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Affiliation(s)
- Yuemin Tian
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, 93053 Regensburg, Germany
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30
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Forrest AS, Joyce TC, Huebner ML, Ayon RJ, Wiwchar M, Joyce J, Freitas N, Davis AJ, Ye L, Duan DD, Singer CA, Valencik ML, Greenwood IA, Leblanc N. Increased TMEM16A-encoded calcium-activated chloride channel activity is associated with pulmonary hypertension. Am J Physiol Cell Physiol 2012; 303:C1229-43. [PMID: 23034390 DOI: 10.1152/ajpcell.00044.2012] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Pulmonary artery smooth muscle cells (PASMCs) are more depolarized and display higher Ca(2+) levels in pulmonary hypertension (PH). Whether the functional properties and expression of Ca(2+)-activated Cl- channels (Cl(Ca)), an important excitatory mechanism in PASMCs, are altered in PH is unknown. The potential role of Cl(Ca) channels in PH was investigated using the monocrotaline (MCT)-induced PH model in the rat. Three weeks postinjection with a single dose of MCT (50 mg/kg ip), the animals developed right ventricular hypertrophy (heart weight measurements) and changes in pulmonary arterial flow (pulse-waved Doppler imaging) that were consistent with increased pulmonary arterial pressure and PH. Whole cell patch experiments revealed an increase in niflumic acid (NFA)-sensitive Ca(2+)-activated Cl(-) current [I(Cl(Ca))] density in PASMCs from large conduit and small intralobar pulmonary arteries of MCT-treated rats vs. aged-matched saline-injected controls. Quantitative RT-PCR and Western blot analysis revealed that the alterations in I(Cl(Ca)) were accompanied by parallel changes in the expression of TMEM16A, a gene recently shown to encode for Cl(Ca) channels. The contraction to serotonin of conduit and intralobar pulmonary arteries from MCT-treated rats exhibited greater sensitivity to nifedipine (1 μM), an l-type Ca(2+) channel blocker, and NFA (30 or 100 μM, with or without 10 μM indomethacin to inhibit cyclooxygenases) or T16A(Inh)-A01 (10 μM), TMEM16A/Cl(Ca) channel inhibitors, than that of control animals. In conclusion, augmented Cl(Ca)/TMEM16A channel activity is a major contributor to the changes in electromechanical coupling of PA in this model of PH. TMEM16A-encoded channels may therefore represent a novel therapeutic target in this disease.
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Affiliation(s)
- Abigail S Forrest
- Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada 89557-0573, USA
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31
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Angermann JE, Forrest AS, Greenwood IA, Leblanc N. Activation of Ca2+-activated Cl- channels by store-operated Ca2+ entry in arterial smooth muscle cells does not require reverse-mode Na+/Ca2+ exchange. Can J Physiol Pharmacol 2012; 90:903-21. [PMID: 22734601 DOI: 10.1139/y2012-081] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The main purpose of this study was to characterize the stimulation of Ca(2+)-activated Cl(-) (Cl(Ca)) by store-operated Ca(2+) entry (SOCE) channels in rabbit pulmonary arterial smooth muscle cells (PASMCs) and determine if this process requires reverse-mode Na(+)/Ca(2+) exchange (NCX). In whole-cell voltage clamped PASMCs incubated with 1 μmol/L nifedipine (Nif) to inhibit Ca(2+) channels, 30 μmol/L cyclopiazonic acid (CPA), a SERCA pump inhibitor, activated a nonselective cation conductance permeable to Na(+) (I(SOC)) during an initial 1-3 s step, ranging from-120 to +60 mV, and Ca(2+)-activated Cl(-) current (I(Cl(Ca))) during a second step to +90 mV that increased with the level of the preceding hyperpolarizing step. Niflumic acid (100 μmol/L), a Cl(Ca) channel blocker, abolished I(Cl(Ca)) but had no effect on I(SOC), whereas the I(SOC) blocker SKF-96365 (50 μmol/L) suppressed both currents. Dual patch clamp and Fluo-4 fluorescence measurements revealed the appearance of CPA-induced Ca(2+) transients of increasing magnitude with increasing hyperpolarizing steps, which correlated with I(Cl(Ca)) amplitude. The absence of Ca(2+) transients at positive potentials following a hyperpolarizing step combined with the observation that SOCE-stimulated I(Cl(Ca)) was unaffected by the NCX blocker KB-R7943 (1 μmol/L) suggest that the SOCE/Cl(Ca) interaction does not require reverse-mode NCX in our conditions.
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Affiliation(s)
- Jeff E Angermann
- School of Community Health Sciences, University of Nevada, Reno, 89557, USA
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32
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Wang M, Yang H, Zheng LY, Zhang Z, Tang YB, Wang GL, Du YH, Lv XF, Liu J, Zhou JG, Guan YY. Downregulation of TMEM16A calcium-activated chloride channel contributes to cerebrovascular remodeling during hypertension by promoting basilar smooth muscle cell proliferation. Circulation 2012; 125:697-707. [PMID: 22215857 DOI: 10.1161/circulationaha.111.041806] [Citation(s) in RCA: 122] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
BACKGROUND The Ca(2+)-activated chloride channel (CaCC) plays an important role in a variety of physiological functions. In vascular smooth muscle cells, CaCC is involved in the regulation of agonist-stimulated contraction and myogenic tone. The physiological functions of CaCC in blood vessels are not fully revealed because of the lack of specific channel blockers and the uncertainty concerning its molecular identity. METHODS AND RESULTS Whole-cell patch-clamp studies showed that knockdown of TMEM16A but not bestrophin-3 attenuated CaCC currents in rat basilar smooth muscle cells. The activity of CaCC in basilar smooth muscle cells isolated from 2-kidney, 2-clip renohypertensive rats was decreased, and CaCC activity was negatively correlated with blood pressure (n=25; P<0.0001) and medial cross-sectional area (n=24; P<0.0001) in basilar artery during hypertension. Both upregulation of CaMKII activity and downregulation of TMEM16A expression contributed to the reduction of CaCC in the hypertensive basilar artery. Western blot results demonstrated that angiotensin II repressed TMEM16A expression in basilar smooth muscle cells (n=6; P<0.01). Knockdown of TMEM16A facilitated and overexpression of TMEM16A inhibited angiotensin II-induced cell cycle transition and cell proliferation determined by flow cytometry and BrdU incorporation (n=6 in each group; P<0.05). TMEM16A affected cell cycle progression mainly through regulating the expression of cyclin D1 and cyclin E. CONCLUSIONS TMEM16A CaCC is a negative regulator of cell proliferation. Downregulation of CaCC may play an important role in hypertension-induced cerebrovascular remodeling, suggesting that modification of the activity of CaCC may be a novel therapeutic strategy for hypertension-associated cardiovascular diseases such as stroke.
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Affiliation(s)
- Mi Wang
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-Sen University, 74 Zhongshan 2 Rd, Guangzhou, China
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33
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Huang F, Wong X, Jan LY. International Union of Basic and Clinical Pharmacology. LXXXV: calcium-activated chloride channels. Pharmacol Rev 2011; 64:1-15. [PMID: 22090471 DOI: 10.1124/pr.111.005009] [Citation(s) in RCA: 135] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Calcium-activated chloride channels (CaCCs) are widely expressed in various tissues and implicated in physiological processes such as sensory transduction, epithelial secretion, and smooth muscle contraction. Transmembrane proteins with unknown function 16 (TMEM16A) has recently been identified as a major component of CaCCs. Detailed molecular analysis of TMEM16A will be needed to understand its structure-function relationships. The role this channel plays in physiological systems remains to be established and is currently a subject of intense investigation.
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Affiliation(s)
- Fen Huang
- Department of Physiology, Howard Hughes Medical Institute, University of California, San Francisco, Mission Bay Campus, San Francisco, CA 94158-2811, USA
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34
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Yamamura A, Yamamura H, Zeifman A, Yuan JXJ. Activity of Ca -activated Cl channels contributes to regulating receptor- and store-operated Ca entry in human pulmonary artery smooth muscle cells. Pulm Circ 2011; 1:269-79. [PMID: 22034612 PMCID: PMC3198647 DOI: 10.4103/2045-8932.83447] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Intracellular Ca2+ plays a fundamental role in regulating cell functions in pulmonary arterial smooth muscle cells (PASMCs). A rise in cytosolic Ca2+ concentration ([Ca2+]cyt) triggers pulmonary vasoconstriction and stimulates PASMC proliferation. [Ca2+]cyt is increased mainly by Ca2+ release from intracellular stores and Ca2+ influx through plasmalemmal Ca2+-permeable channels. Given the high concentration of intracellular Cl- in PASMCs, Ca2+-activated Cl-(ClCa) channels play an important role in regulating membrane potential and cell excitability of PASMCs. In this study, we examined whether activity of ClCa channels was involved in regulating [Ca2+]cyt in human PASMCs via regulating receptor- (ROCE) and store- (SOCE) operated Ca2+ entry. The data demonstrated that an angiotensin II (100 nM)-mediated increase in [Ca2+]cyt via ROCE was markedly attenuated by the ClCa channel inhibitors, niflumic acid (100 μM), flufenamic acid (100 μM), and 4,4’-diisothiocyanatostilbene-2,2’-disulfonic acid (100 μM). The inhibition of ClCa channels by niflumic acid and flufenamic acid significantly reduced both transient and plateau phases of SOCE that was induced by passive depletion of Ca2+ from the sarcoplasmic reticulum by 10 μM cyclopiazonic acid. In addition, ROCE and SOCE were abolished by SKF-96365 (50 μM) and 2-aminoethyl diphenylborinate (100 μM), and were slightly decreased in the presence of diltiazem (10 μM). The electrophysiological and immunocytochemical data indicate that ClCa currents were present and TMEM16A was functionally expressed in human PASMCs. The results from this study suggest that the function of ClCa channels, potentially formed by TMEM16A proteins, contributes to regulating [Ca2+]cyt by affecting ROCE and SOCE in human PASMCs.
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Affiliation(s)
- Aya Yamamura
- Department of Medicine, Section of Pulmonary, Critical Care, Sleep and Allergy, Institute for Personalized Respiratory Medicine, Center for Cardiovascular Research, and Department of Pharmacology, University of Illinois at Chicago, Chicago, Illinois, USA
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35
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Abstract
This minireview discusses vasomotion, which is the oscillation in tone of blood vessels leading to flowmotion. We will briefly discuss the prevalence of vasomotion and its potential physiological and pathophysiological relevance. We will also discuss the models that have been suggested to explain how a coordinated oscillatory activity of the smooth muscle tone can occur and emphasize the role of the endothelium, the handling of intracellular Ca(2+) and the role of smooth muscle cell ion conductances. It is concluded that vasomotion is likely to enhance tissue dialysis, although this concept still requires more experimental verification, and that an understanding at the molecular level for the pathways leading to vasomotion is beginning to emerge.
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Affiliation(s)
- C Aalkjær
- Department of Physiology and Biophysics, The Water and Salt Centre, Aarhus University, Denmark.
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36
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Ferrera L, Scudieri P, Sondo E, Caputo A, Caci E, Zegarra-Moran O, Ravazzolo R, Galietta LJV. A minimal isoform of the TMEM16A protein associated with chloride channel activity. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:2214-23. [PMID: 21645494 PMCID: PMC3130926 DOI: 10.1016/j.bbamem.2011.05.017] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/11/2011] [Revised: 04/11/2011] [Accepted: 05/20/2011] [Indexed: 11/28/2022]
Abstract
TMEM16A protein, also known as anoctamin-1, has been recently identified as an essential component of Ca(2+)-activated Cl(-) channels. We previously reported the existence of different TMEM16A isoforms generated by alternative splicing. In the present study, we have determined the functional properties of a minimal TMEM16A protein. This isoform, called TMEM16A(0), has a significantly shortened amino-terminus and lacks three alternative segments localized in the intracellular regions of the protein (total length: 840 amino acids). TMEM16A(0) expression is associated with Ca(2+)-activated Cl(-) channel activity as measured by three different functional assays based on the halide-sensitive yellow fluorescent protein, short-circuit current recordings, and patch-clamp technique. However, compared to a longer isoform, TMEM16(abc) (total length: 982 amino acids), TMEM16A(0) completely lacks voltage-dependent activation. Furthermore, TMEM16A(0) and TMEM16A(abc) have similar but not identical responses to extracellular anion replacement, thus suggesting a difference in ion selectivity and conductance. Our results indicate that TMEM16A(0) has the basic domains required for anion transport and Ca(2+)-sensitivity. However, the absence of alternative segments, which are present in more complex isoforms of TMEM16A, modifies the channel gating and ion transport ability.
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Affiliation(s)
- Loretta Ferrera
- Laboratorio di Genetica Molecolare, Largo Gerolamo Gaslini, Istituto Giannina Gaslini, 16147 Genova, Italy
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37
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Ferrera L, Caputo A, Galietta LJV. TMEM16A protein: a new identity for Ca(2+)-dependent Cl⁻ channels. Physiology (Bethesda) 2011; 25:357-63. [PMID: 21186280 DOI: 10.1152/physiol.00030.2010] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Ca(+)-dependent Cl⁻ channels (CaCCs) play a variety of physiological roles in different organs and tissues, including transepithelial Cl⁻ secretion, smooth muscle contraction, regulation of neuronal excitability, and transduction of sensory stimuli. The recent identification of TMEM16A protein as an important component of CaCCs should allow a better understanding of their physiological role, structure-function relationship, and regulatory mechanisms.
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Affiliation(s)
- Loretta Ferrera
- Laboratory of Molecular Genetics, Istituto Giannina Gaslini, Genova, Italy
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38
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Tian Y, Kongsuphol P, Hug M, Ousingsawat J, Witzgall R, Schreiber R, Kunzelmann K. Calmodulin-dependent activation of the epithelial calcium-dependent chloride channel TMEM16A. FASEB J 2010; 25:1058-68. [PMID: 21115851 DOI: 10.1096/fj.10-166884] [Citation(s) in RCA: 119] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
TMEM16A (anoctamin 1, Ano1), a member of a family of 10 homologous proteins, has been shown to form an essential component of Ca(2+)-activated Cl(-) channels. TMEM16A-null mice exhibit severe defects in epithelial transport along with tracheomalacia and death within 1 mo after birth. Despite its outstanding physiological significance, the mechanisms for activation of TMEM16A remain obscure. TMEM16A is activated on increase in intracellular Ca(2+), but it is unclear whether Ca(2+) binds directly to the channel or whether additional components are required. We demonstrate that TMEM16A is strictly membrane localized and requires cytoskeletal interactions to be fully activated. Despite the need for cytosolic ATP for full activation, phosphorylation by protein kinases is not required. In contrast, the Ca(2+) binding protein calmodulin appears indispensable and interacts physically with TMEM16A. Openers of small- and intermediate-conductance Ca(2+)-activated potassium channels known to interact with calmodulin, such as 1-EBIO, DCEBIO, or riluzole, also activated TMEM16A. These results reinforce the use of these compounds for activation of electrolyte secretion in diseases such as cystic fibrosis.
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Affiliation(s)
- Yuemin Tian
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
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Wang YX, Zheng YM. Role of ROS signaling in differential hypoxic Ca2+ and contractile responses in pulmonary and systemic vascular smooth muscle cells. Respir Physiol Neurobiol 2010; 174:192-200. [PMID: 20713188 DOI: 10.1016/j.resp.2010.08.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2010] [Revised: 08/06/2010] [Accepted: 08/09/2010] [Indexed: 01/25/2023]
Abstract
Hypoxia causes a large increase in [Ca2+]i and attendant contraction in pulmonary artery smooth muscle cells (PASMCs), but not in systemic artery SMCs. The different responses meet the respective functional needs in these two distinct vascular myocytes; however, the underlying molecular mechanisms are not well known. We and other investigators have provided extensive evidence to reveal that voltage-dependent K+ (KV) channels, canonical transient receptor potential (TRPC) channels, ryanodine receptor Ca2+ release channels (RyRs), cyclic adenosine diphosphate-ribose, FK506 binding protein 12.6, protein kinase C, NADPH oxidase and reactive oxygen species (ROS) are the essential effectors and signaling intermediates in the hypoxic increase in [Ca2+]i in PASMCs and HPV, but they may not primarily underlie the diverse cellular responses in pulmonary and systemic vascular myocytes. Hypoxia significantly increases mitochondrial ROS generation in PASMCs, which can induce intracellular Ca2+ release by opening RyRs, and may also cause extracellular Ca2+ influx by inhibiting KV channels and activating TRPC channels, leading to a large increase in [Ca2+]i in PASMCs and HPV. In contrast, hypoxia has no or a minor effect on mitochondrial ROS generation in systemic SMCs, thereby causing no change or a negligible increase in [Ca2+]i and contraction. Further preliminary work indicates that Rieske iron-sulfur protein in the mitochondrial complex III may perhaps serve as a key initial molecular determinant for the hypoxic increase in [Ca2+]i in PASMCs and HPV, suggesting its potential important role in different cellular changes to respond to hypoxic stimulation in pulmonary and systemic artery myocytes. All these findings have greatly improved our understanding of the molecular processes for the differential hypoxic Ca2+ and contractile responses in vascular SMCs from distinct pulmonary and systemic circulation systems.
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Affiliation(s)
- Yong-Xiao Wang
- Center for Cardiovascular Sciences, Albany Medical College, 47 New Scotland Avenue, Albany, NY 12208, USA.
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Davis AJ, Forrest AS, Jepps TA, Valencik ML, Wiwchar M, Singer CA, Sones WR, Greenwood IA, Leblanc N. Expression profile and protein translation of TMEM16A in murine smooth muscle. Am J Physiol Cell Physiol 2010; 299:C948-59. [PMID: 20686072 DOI: 10.1152/ajpcell.00018.2010] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Recently, overexpression of the genes TMEM16A and TMEM16B has been shown to produce currents qualitatively similar to native Ca(2+)-activated Cl(-) currents (I(ClCa)) in vascular smooth muscle. However, there is no information about this new gene family in vascular smooth muscle, where Cl(-) channels are a major depolarizing mechanism. Qualitatively similar Cl(-) currents were evoked by a pipette solution containing 500 nM Ca(2+) in smooth muscle cells isolated from BALB/c mouse portal vein, thoracic aorta, and carotid artery. Quantitative PCR using SYBR Green chemistry and primers specific for transmembrane protein (TMEM) 16A or the closely related TMEM16B showed TMEM16A expression as follows: portal vein > thoracic aorta > carotid artery > brain. In addition, several alternatively spliced variant transcripts of TMEM16A were detected. In contrast, TMEM16B expression was very low in smooth muscle. Western blot analysis with different antibodies directed against TMEM16A revealed a number of products with a consistent band at ∼120 kDa, except portal vein, where an 80-kDa band predominated. TMEM16A protein was identified in the smooth muscle layers of 4-μm-thick slices of portal vein, thoracic aorta, and carotid artery. In isolated myocytes, fluorescence specific to a TMEM16A antibody was detected diffusely throughout the cytoplasm, as well as near the membrane. The same antibody used in Western blot analysis of lysates from vascular tissues also recognized an ∼147-kDa mouse TMEM16A-green fluorescent protein (GFP) fusion protein expressed in HEK 293 cells, which correlated to a similar band detected by a GFP antibody. Patch-clamp experiments revealed that I(ClCa) generated by transfection of TMEM16A-GFP in HEK 293 cells displayed remarkable similarities to I(ClCa) recorded in vascular myocytes, including slow kinetics, steep outward rectification, and a response similar to the pharmacological agent niflumic acid. This study shows that TMEM16A expression is robust in murine vascular smooth muscle cells, consolidating the view that this gene is a viable candidate for the native Ca(2+)-activated Cl(-) channel in this cell type.
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Affiliation(s)
- Alison J Davis
- Division of Biomedical Sciences, St. George's, University of London, London, United Kingdom
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Lin H, Pallone TL, Cao C. Murine vasa recta pericyte chloride conductance is controlled by calcium, depolarization, and kinase activity. Am J Physiol Regul Integr Comp Physiol 2010; 299:R1317-25. [PMID: 20686172 DOI: 10.1152/ajpregu.00129.2010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We used the whole cell patch-clamp technique to investigate the regulation of descending vasa recta (DVR) pericyte Ca(2+)-dependent Cl(-) currents (CaCC) by cytoplasmic Ca(2+) concentration ([Ca](CYT)), voltage, and kinase activity. Murine CaCC increased with voltage and electrode Ca(2+) concentration. The current saturated at [Ca](CYT) of ∼1,000 nM and exhibited an EC(50) for Ca(2+) of ∼500 nM, independent of depolarization potential. Activation time constants were between 100 and 200 ms, independent of electrode Ca(2+). Repolarization-related tail currents elicited by stepping from +100 mV to varying test potentials exhibited deactivation time constants of 50-200 ms that increased with voltage when electrode [Ca](CYT) was 1,000 nM. The calmodulin inhibitor N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide hydrochloride (W-7, 30 μM) blocked CaCC. The myosin light chain kinase blockers 1-(5-iodonaphthalene-1-sulfonyl)-1H-hexahydro-1,4-diazepine hydrochloride (ML-7, 1-50 μM) and 1-(5-chloronaphthalene-1-sulfonyl)-1H-hexahydro-1,4-diazepine hydrochloride (ML-9, 10 μM) were similarly effective. Resting pericytes were hyperpolarized by ML-7. Pericytes exposed to ANG II (10 nM) depolarized from a baseline of -50 ± 6 to -29 ± 3 mV and were repolarized to -63 ± 7 mV by exposure to 50 μM ML-7. The Ca(2+)/calmodulin-dependent kinase inhibitor KN-93 reduced pericyte CaCC only when it was present in the electrode and extracellular buffer from the time of membrane break-in. We conclude that murine DVR pericytes are modulated by [Ca](CYT), membrane potential, and phosphorylation events, suggesting that Ca(2+)-dependent Cl(-) conductance may be a target for regulation of vasoactivity and medullary blood flow in vivo.
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Affiliation(s)
- Hai Lin
- Division of Nephrology, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, USA
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Calcium activates a chloride conductance likely involved in olfactory receptor neuron repolarization in the moth Spodoptera littoralis. J Neurosci 2010; 30:6323-33. [PMID: 20445058 DOI: 10.1523/jneurosci.0261-10.2010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The response of insect olfactory receptor neurons (ORNs) to odorants involves the opening of Ca(2+)-permeable channels, generating an increase in intracellular Ca(2+) concentration. Here, we studied the downstream effect of this Ca(2+) rise in cultured ORNs of the moth Spodoptera littoralis. Intracellular dialysis of Ca(2+) from the patch pipette in whole-cell patch-clamp configuration activated a conductance with a K(1/2) of 2.8 microm. Intracellular and extracellular anionic and cationic substitutions demonstrated that Cl(-) carries this current. The anion permeability sequence I(-) > NO(3)(-) > Br(-) > Cl(-) > CH(3)SO(3)(-) >> gluconate(-) of the Ca(2+)-activated Cl(-) channel suggests a weak electrical field pore of the channel. The Ca(2+)-activated current partly inactivated over time and did not depend on protein kinase C (PKC) and CaMKII activity or on calmodulin. Application of Cl(-) channel blockers, flufenamic acid, 5-nitro-2-(3-phenylpropylamino) benzoic acid, or niflumic acid reversibly blocked the Ca(2+)-activated current. In addition, lowering Cl(-) concentration in the sensillar lymph bathing the ORN outer dendrites caused a significant delay in pheromone response termination in vivo. The present work identifies a new Cl(-) conductance activated by Ca(2+) in insect ORNs presumably required for ORN repolarization.
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Manoury B, Tamuleviciute A, Tammaro P. TMEM16A/anoctamin 1 protein mediates calcium-activated chloride currents in pulmonary arterial smooth muscle cells. J Physiol 2010; 588:2305-14. [PMID: 20421283 DOI: 10.1113/jphysiol.2010.189506] [Citation(s) in RCA: 137] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Calcium-activated chloride channels (CaCCs) play important roles in several physiological processes. In vascular smooth muscle, activation of these ion channels by agonist-induced Ca(2+) release results in membrane depolarization and vasoconstriction. The molecular identity of vascular CaCCs is not fully defined. Here we present evidence that TMEM16A (or anoctamin 1), a member of the transmembrane 16 (TMEM16) protein family, forms CaCCs in pulmonary artery smooth muscle cells (PASMCs). Patch-clamp analysis in freshly isolated PASMCs revealed strongly outward-rectifying, slowly activating Ca(2+)-activated Cl(-) currents sharing a high degree of similarity with heterologous TMEM16A currents. TMEM16A mRNA was identified in rat and human pulmonary arteries and various other vascular smooth muscle cell types. Further analyses revealed that several TMEM16A splice variants were detected in rat PASMCs and that TMEM16F and TMEM16K were also expressed in these cells, while TMEM16B, TMEM16D and TMEM16E were all at least 50 times less abundantly expressed and the remaining TMEM16 family members were absent. Downregulation of TMEM16A gene expression in primary cultures of rat PASMCs, with small interfering RNAs, was accompanied by almost total loss of whole-cell CaCC currents. Based on these results, we propose that TMEM16A is the major constituent of the vascular calcium-activated chloride channel in rat pulmonary artery smooth muscle.
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Affiliation(s)
- Boris Manoury
- Faculty of Life Sciences, University of Manchester, Manchester, UK
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Hao LY, Wang WY, Minobe E, Han DY, Xu JJ, Kameyama A, Kameyama M. The distinct roles of calmodulin and calmodulin kinase II in the reversal of run-down of L-type Ca(2+) channels in guinea-pig ventricular myocytes. J Pharmacol Sci 2010; 111:416-25. [PMID: 20019447 DOI: 10.1254/jphs.09094fp] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
In this study, we investigated the roles of calmodulin kinase II (CaMKII) and calmodulin (CaM) in the reversal of run-down of L-type Ca(2+) channels. Single Ca(2+)-channel activities in guinea-pig ventricular myocytes were recorded using the patch-clamp technique, and run-down of the channel activities was induced by inside-out patch formation in the basic internal solution. At 1 min after patch excision, 1 - 30 muM CaMKII mutant T286D (CaMKIIT286D), a constitutively active type of CaMKII, induced the Ca(2+)-channel activities to only 2% - 10% of that recorded in the cell-attached mode. However, in the presence of CaMKIIT286D, the time-dependent attenuation of CaM's effects in the reversal of run-down was abolished. A GST-fusion protein containing amino acids 1509 - 1789 of the C-terminal region of guinea-pig Cav1.2 (CT1) was prepared. In pull-down assays, CT1 treated with CaMKIIT286D showed a higher affinity for CaM compared with CT1 treated with phosphatase. We propose a model in which CaMKII-mediated phosphorylation of the channels regulates the binding of CaM to the channels in the reversal of run-down of L-type Ca(2+) channels.
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Affiliation(s)
- Li-Ying Hao
- Department of Pharmaceutical Toxicology, School of Pharmacological Sciences, China Medical University, Shenyang 110001, China.
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Sones WR, Davis AJ, Leblanc N, Greenwood IA. Cholesterol depletion alters amplitude and pharmacology of vascular calcium-activated chloride channels. Cardiovasc Res 2010; 87:476-84. [PMID: 20172862 DOI: 10.1093/cvr/cvq057] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
AIMS Calcium-activated chloride channels (CACCs) share common pharmacological properties with Kcnma1-encoded large conductance K(+) channels (BK(Ca) or K(Ca)1.1) and it has been suggested that they may co-exist in a macromolecular complex. As K(Ca)1.1 channels are known to localize to cholesterol and caveolin-rich lipid rafts (caveolae), the present study investigated whether Ca(2+)-sensitive Cl(-) currents in vascular myocytes were affected by the cholesterol depleting agent methyl-beta-cyclodextrin (M-betaCD). METHODS AND RESULTS Calcium-activated chloride and potassium currents were recorded from single murine portal vein myocytes in whole cell voltage clamp. Western blot was undertaken following sucrose gradient ultracentrifugation using protein lysates from whole portal veins. Ca(2+)-activated Cl(-) currents were augmented by 3 mg mL(-1) M-betaCD with a rapid time course (t(0.5) = 1.8 min). M-betaCD had no effect on the bi-modal response to niflumic acid or anthracene-9-carboxylate but completely removed the inhibitory effects of the K(Ca)1.1 blockers, paxilline and tamoxifen, as well as the stimulatory effect of the K(Ca)1.1 activator NS1619. Discontinuous sucrose density gradients followed by western blot analysis revealed that the position of lipid raft markers caveolin and flotillin-2 was altered by 15 min application of 3 mg mL(-1) M-betaCD. The position of K(Ca)1.1 and the newly identified candidate for CACCs, TMEM16A, was also affected by M-betaCD. CONCLUSION These data reveal that CACC properties are influenced by lipid raft integrity.
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Affiliation(s)
- William R Sones
- Division of Basic Medical Sciences, St George's, University of London, London SW17 0RE, UK
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Intricate interaction between store-operated calcium entry and calcium-activated chloride channels in pulmonary artery smooth muscle cells. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 661:31-55. [PMID: 20204722 DOI: 10.1007/978-1-60761-500-2_3] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Ca(2+)-activated Cl-() channels (Cl(Ca)) represent an important excitatory mechanism in vascular smooth muscle cells. Active accumulation of Cl-() by several classes of anion transporters results in an equilibrium potential for this ion about 30 mV more positive than the resting potential. Stimulation of Cl(Ca) channels leads to membrane depolarization, which enhances Ca(2+) entry through voltage-gated Ca(2+) channels and leads to vasoconstriction. Cl(Ca) channels can be activated by distinct sources of Ca(2+) that include (1) mobilization from intracellular Ca(2+) stores (ryanodine or inositol 1,4,5-trisphosphate [InsP(3)]) and (2) Ca(2+) entry through voltage-gated Ca(2+) channels or reverse-mode Na(+)/Ca(2+) exchange. The present study was undertaken to determine whether Ca(2+) influx triggered by store depletion (store-operated calcium entry, SOCE) activates Cl(Ca) channels in rabbit pulmonary artery (PA) smooth muscle. Classical store depletion protocols involving block of sarcoplasmic reticular Ca(2+) reuptake with thapsigargin (TG; 1 microM) or cyclopiazonic acid (CPA; 30 microM) led to a consistent nifedipine-insensitive contraction of intact PA rings and rise in intracellular Ca(2+) concentration in single PA myocytes that required the presence of extracellular Ca(2+). In patch clamp experiments, TG or CPA activated a time-independent nonselective cation current (I (SOC)) that (1) reversed between -10 and 0 mV; (2) displayed the typical "N"-shaped current-voltage relationship; and (3) was sensitive to the (I (SOC)) blocker by SKF-96365 (50 microM). In double-pulse protocol experiments, the amplitude of I (SOC) was varied by altering membrane potential during an initial step that was followed by a second constant step to +90 mV to register Ca(2+)-activated Cl(-) current, I (Cl(Ca)). The niflumic acid-sensitive time-dependent I (Cl(Ca)) at +90 mV increased in proportion to the magnitude of the preceding hyperpolarizing step, an effect attributed to graded membrane potential-dependent Ca(2+) entry through I (SOC) and confirmed in dual patch clamp and Fluo-5 experiments to record membrane current and free intracellular Ca(2+) concentration simultaneously. Reverse-transcription polymerase chain reaction (RT-PCR) experiments confirmed the expression of several molecular determinants of SOCE, including transient receptor potential canonical (TRPC) 1, TRPC4, and TRPC6; stromal interacting molecule (STIM) 1 and 2; and Orai1 and 2, as well as the novel and probable molecular candidates thought to encode for Cl(Ca) channels transmembrane protein 16A (TMEM16A) Anoctamin 1 (ANO1) and B (ANO2). Ourpreliminary investigation provides new evidence for a Ca(2+) entry pathway consistent with store-operated Ca(2+) entry signaling that can activate Ca(2+)-activated Cl-() channels in rabbit PA myocytes. We hypothesize that this mechanism may be important in the regulation of membrane potential, Ca(2+) influx, and tone in these cells under physiological and pathophysiological conditions.
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Ferrera L, Caputo A, Ubby I, Bussani E, Zegarra-Moran O, Ravazzolo R, Pagani F, Galietta LJV. Regulation of TMEM16A chloride channel properties by alternative splicing. J Biol Chem 2009; 284:33360-8. [PMID: 19819874 DOI: 10.1074/jbc.m109.046607] [Citation(s) in RCA: 176] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Expression of TMEM16A protein is associated with the activity of Ca(2+)-activated Cl(-) channels. TMEM16A primary transcript undergoes alternative splicing. thus resulting in the generation of multiple isoforms. We have determined the pattern of splicing and assessed the functional properties of the corresponding TMEM16A variants. We found three alternative exons, 6b, 13, and 15, coding for segments of 22, 4, and 26 amino acids, respectively, which are differently spliced in human organs. By patch clamp experiments on transfected cells, we found that skipping of exon 6b changes the Ca(2+) sensitivity by nearly 4-fold, resulting in Cl(-) currents requiring lower Ca(2+) concentrations to be activated. At the membrane potential of 80 mV, the apparent half-effective concentration decreases from 350 to 90 nm when the segment corresponding to exon 6b is excluded. Skipping of exon 13 instead strongly reduces the characteristic time-dependent activation observed for Ca(2+)-activated Cl(-) channels at positive membrane potentials. This effect was also obtained by deleting only the second pair of amino acids corresponding to exon 13. Alternative splicing appears as an important mechanism to regulate the voltage and Ca(2+) dependence of the TMEM16A-dependent Cl(-) channels in a tissue-specific manner.
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Affiliation(s)
- Loretta Ferrera
- Laboratory of Molecular Genetics, Istituto Giannina Gaslini, Largo G. Gaslini 5, 16147 Genova
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Wiwchar M, Ayon R, Greenwood IA, Leblanc N. Phosphorylation alters the pharmacology of Ca(2+)-activated Cl channels in rabbit pulmonary arterial smooth muscle cells. Br J Pharmacol 2009; 158:1356-65. [PMID: 19785656 DOI: 10.1111/j.1476-5381.2009.00405.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND AND PURPOSE Ca(2+)-activated Cl(-) currents (I(Cl(Ca))) in arterial smooth muscle cells are inhibited by phosphorylation. The Ca(2+)-activated Cl(-) channel (Cl(Ca)) blocker niflumic acid (NFA) produces a paradoxical dual effect on I(Cl(Ca)), causing stimulation or inhibition at potentials below or above 0 mV respectively. We tested whether the effects of NFA on I(Cl(Ca)) were modulated by phosphorylation. EXPERIMENTAL APPROACH I(Cl(Ca)) was elicited with 500 nM free internal Ca(2+) in rabbit pulmonary artery myocytes. The state of global phosphorylation was altered by cell dialysis with either 5 mM ATP or 0 mM ATP with or without an inhibitor of calmodulin-dependent protein kinase type II, KN-93 (10 microM). KEY RESULTS Dephosphorylation enhanced the ability of 100 microM NFA to inhibit I(Cl(Ca)). This effect was attributed to a large negative shift in the voltage-dependence of block, which was converted to stimulation at potentials <-50 mV, approximately 70 mV more negative than cells dialysed with 5 mM ATP. NFA dose-dependently blocked I(Cl(Ca)) in the range of 0.1-250 microM in cells dialysed with 0 mM ATP and KN-93, which contrasted with the stimulation induced by 0.1 microM, which converted to block at concentrations >1 microM when cells were dialysed with 5 mM ATP. CONCLUSIONS AND IMPLICATIONS Our data indicate that the presumed state of phosphorylation of the pore-forming or regulatory subunit of Cl(Ca) channels influenced the interaction of NFA in a manner that obstructs interaction of the drug with an inhibitory binding site.
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Affiliation(s)
- M Wiwchar
- Department of Pharmacology, Center of Biomedical Research Excellence (COBRE), University of Nevada School of Medicine, Reno, NV 89557-0270, USA
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Ayon R, Sones W, Forrest AS, Wiwchar M, Valencik ML, Sanguinetti AR, Perrino BA, Greenwood IA, Leblanc N. Complex phosphatase regulation of Ca2+-activated Cl- currents in pulmonary arterial smooth muscle cells. J Biol Chem 2009; 284:32507-21. [PMID: 19767392 DOI: 10.1074/jbc.m109.050401] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The present study was undertaken to determine whether the two ubiquitously expressed Ca(2+)-independent phosphatases PP1 and PP2A regulate Ca(2+)-activated Cl(-) currents (I(Cl(Ca))) elicited by 500 nM [Ca(2+)](i) in rabbit pulmonary artery (PA) myocytes dialyzed with or without 3 mM ATP. Reverse transcription-PCR experiments revealed the expression of PP1alpha, PP1beta/delta, PP1gamma, PP2Aalpha, PP2Abeta, PP2Balpha (calcineurin (CaN) Aalpha), and PP2Bbeta (CaN Abeta) but not PP2Bgamma (CaN Agamma) in rabbit PA. Western blot and immunofluorescence experiments confirmed the presence of all three PP1 isoforms and PP2A. Intracellular dialysis with a peptide inhibitor of calcineurin (CaN-AIP); the non-selective PP1/PP2A inhibitors okadaic acid (0.5, 10, or 30 nM), calyculin A (10 nM), or cantharidin (100 nM); and the selective PP1 inhibitor NIPP-1 (100 pM) potently antagonized the recovery of I(Cl(Ca)) in cells dialyzed with no ATP, whereas the PP2A-selective antagonist fostriecin (30 or 150 nM) was ineffective. The combined application of okadaic acid (10 nM) and CaN-autoinhibitory peptide (50 microM) did not potentiate the response of I(Cl(Ca)) in 0 ATP produced by maximally inhibiting CaN or PP1/PP2A alone. Consistent with the non-additive effects of either classes of phosphatases, the PP1 inhibitor NIPP-1 (100 pM) antagonized the recovery of I(Cl(Ca)) induced by exogenous CaN Aalpha (0.5 microM). These results demonstrate that I(Cl(Ca)) in PA myocytes is regulated by CaN and PP1 and/or PP2A. Our data also suggest the existence of a functional link between these two classes of phosphatases.
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Affiliation(s)
- Ramon Ayon
- Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada 89557, USA
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50
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Sones WR, Leblanc N, Greenwood IA. Inhibition of vascular calcium-gated chloride currents by blockers of KCa1.1, but not by modulators of KCa2.1 or KCa2.3 channels. Br J Pharmacol 2009; 158:521-31. [PMID: 19645713 DOI: 10.1111/j.1476-5381.2009.00332.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND AND PURPOSE Recent pharmacological studies have proposed there is a high degree of similarity between calcium-activated Cl(-) channels (CaCCs) and large conductance, calcium-gated K(+) channels (K(Ca)1.1). The goal of the present study was to ascertain whether blockers of K(Ca)1.1 inhibited calcium-activated Cl(-) currents (I(ClCa)) and if the pharmacological overlap between K(Ca)1.1 and CaCCs extends to intermediate and small conductance, calcium-activated K(+) channels. EXPERIMENTAL APPROACHES Whole-cell Cl(-) and K(+) currents were recorded from murine portal vein myocytes using the whole-cell variant of the patch clamp technique. CaCC currents were evoked by pipette solutions containing 500 nM free [Ca(2+)]. KEY RESULTS The selective K(Ca)1.1 blocker paxilline (1 microM) inhibited I(ClCa) by approximately 90%, whereas penitrem A (1 microM) and iberiotoxin (100 and 300 nM) reduced the amplitude of I(ClCa) by approximately 20%, as well as slowing channel deactivation. Paxilline also abolished the stimulatory effect of niflumic acid on the CaCC. In contrast, an antibody against the Ca(2+)-binding domain of murine K(Ca)1.1 had no effect on I(ClCa) while inhibiting spontaneous K(Ca)1.1 currents. Structurally different modulators of small and intermediate conductance calcium-activated K(+) channels (K(Ca)2.1 and K(Ca)2.3), namely 1-EBIO, (100 microM); NS309, (1 microM); TRAM-34, (10 microM); UCL 1684, (1 microM) had no effect on I(ClCa). CONCLUSIONS AND IMPLICATIONS These data show that the selective K(Ca)1.1 blockers also reduce I(ClCa) considerably. However, the pharmacological overlap that exists between CaCCs and K(Ca)1.1 does not extend to the calcium-binding domain or to other calcium-gated K(+) channels.
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Affiliation(s)
- W R Sones
- Division of Basic Medical Sciences, St George's, University of London, London, UK
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