1
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Markwardt F, Schön EC, Raycheva M, Malisetty A, Hawro Yakoob S, Berthold M, Schmalzing G. Two serial filters control P2X7 cation selectivity, Ser342 in the central pore and lateral acidic residues at the cytoplasmic interface. PNAS NEXUS 2024; 3:pgae349. [PMID: 39262850 PMCID: PMC11388005 DOI: 10.1093/pnasnexus/pgae349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2024] [Accepted: 07/31/2024] [Indexed: 09/13/2024]
Abstract
The human P2X7 receptor (hP2X7R) is a homotrimeric cell surface receptor gated by extracellular ATP4- with two transmembrane helices per subunit, TM1 and TM2. A ring of three S342 residues, one from each pore-forming TM2 helix, located halfway across the membrane bilayer, functions to close and open the gate in the apo and ATP4--bound open states, respectively. The hP2X7R is selective for small inorganic cations, but can also conduct larger organic cations such as Tris+. Here, we show by voltage-clamp electrophysiology in Xenopus laevis oocytes that mutation of S342 residues to positively charged lysines decreases the selectivity for Na+ over Tris+, but maintains cation selectivity. Deep in the membrane, laterally below the S342 ring are nine acidic residues arranged as an isosceles triangle consisting of residues E14, D352, and D356 on each side, which do not move significantly during gating. When the E14K mutation is combined with lysine substitutions of D352 and/or D356, cation selectivity is lost and permeation of the small anion Cl- is allowed. Lysine substitutions of S342 together with D352 or E14 plus D356 in the acidic triangle convert the hP2X7R mutant to a fully Cl--selective ATP4--gated receptor. We conclude that the ion selectivity of wild-type hP2X7R is determined by two sequential filters in one single pathway: (i) a primary size filter, S342, in the membrane center and (ii) three cation filters lateral to the channel axis, one per subunit interface, consisting of a total of nine acidic residues at the cytoplasmic interface.
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Affiliation(s)
- Fritz Markwardt
- Julius-Bernstein-Institute of Physiology, Martin-Luther-University, Magdeburger Straße 6, D-06097 Halle/Saale, Germany
| | - Eike Christian Schön
- Julius-Bernstein-Institute of Physiology, Martin-Luther-University, Magdeburger Straße 6, D-06097 Halle/Saale, Germany
| | - Michaela Raycheva
- Institute of Clinical Pharmacology, RWTH Aachen University, Wendlingweg 2, D-52074 Aachen, Germany
| | - Aparna Malisetty
- Institute of Clinical Pharmacology, RWTH Aachen University, Wendlingweg 2, D-52074 Aachen, Germany
| | - Sanaria Hawro Yakoob
- Institute of Clinical Pharmacology, RWTH Aachen University, Wendlingweg 2, D-52074 Aachen, Germany
| | - Malte Berthold
- Julius-Bernstein-Institute of Physiology, Martin-Luther-University, Magdeburger Straße 6, D-06097 Halle/Saale, Germany
| | - Günther Schmalzing
- Institute of Clinical Pharmacology, RWTH Aachen University, Wendlingweg 2, D-52074 Aachen, Germany
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2
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Liang P, Wan YCS, Yu K, Hartzell HC, Yang H. Niclosamide potentiates TMEM16A and induces vasoconstriction. J Gen Physiol 2024; 156:e202313460. [PMID: 38814250 PMCID: PMC11138202 DOI: 10.1085/jgp.202313460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 03/15/2024] [Accepted: 05/22/2024] [Indexed: 05/31/2024] Open
Abstract
The TMEM16A calcium-activated chloride channel is a promising therapeutic target for various diseases. Niclosamide, an anthelmintic medication, has been considered a TMEM16A inhibitor for treating asthma and chronic obstructive pulmonary disease (COPD) but was recently found to possess broad-spectrum off-target effects. Here, we show that, under physiological Ca2+ (200-500 nM) and voltages, niclosamide acutely potentiates TMEM16A. Our computational and functional characterizations pinpoint a putative niclosamide binding site on the extracellular side of TMEM16A. Mutations in this site attenuate the potentiation. Moreover, niclosamide potentiates endogenous TMEM16A in vascular smooth muscle cells, triggers intracellular calcium increase, and constricts the murine mesenteric artery. Our findings advise caution when considering clinical applications of niclosamide as a TMEM16A inhibitor. The identification of the putative niclosamide binding site provides insights into the mechanism of TMEM16A pharmacological modulation and provides insights into developing specific TMEM16A modulators to treat human diseases.
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Affiliation(s)
- Pengfei Liang
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
| | - Yui Chun S. Wan
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
| | - Kuai Yu
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, USA
| | - H. Criss Hartzell
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, USA
| | - Huanghe Yang
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
- Department of Neurobiology, Duke University School of Medicine, Durham, NC, USA
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3
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Arreola J, López-Romero AE, Huerta M, Guzmán-Hernández ML, Pérez-Cornejo P. Insights into the function and regulation of the calcium-activated chloride channel TMEM16A. Cell Calcium 2024; 121:102891. [PMID: 38772195 DOI: 10.1016/j.ceca.2024.102891] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Revised: 04/23/2024] [Accepted: 04/23/2024] [Indexed: 05/23/2024]
Abstract
The TMEM16A channel, a member of the TMEM16 protein family comprising chloride (Cl-) channels and lipid scramblases, is activated by the free intracellular Ca2+ increments produced by inositol 1,4,5-trisphosphate (IP3)-induced Ca2+ release after GqPCRs or Ca2+ entry through cationic channels. It is a ubiquitous transmembrane protein that participates in multiple physiological functions essential to mammals' lives. TMEM16A structure contains two identical 10-segment monomers joined at their transmembrane segment 10. Each monomer harbours one independent hourglass-shaped pore gated by Ca2+ ligation to an orthosteric site adjacent to the pore and controlled by two gates. The orthosteric site is created by assembling negatively charged glutamate side chains near the pore´s cytosolic end. When empty, this site generates an electrostatic barrier that controls channel rectification. In addition, an isoleucine-triad forms a hydrophobic gate at the boundary of the cytosolic vestibule and the inner side of the neck. When the cytosolic Ca2+ rises, one or two Ca2+ ions bind to the orthosteric site in a voltage (V)-dependent manner, thus neutralising the electrostatic barrier and triggering an allosteric gating mechanism propagating via transmembrane segment 6 to the hydrophobic gate. These coordinated events lead to pore opening, allowing the Cl- flux to ensure the physiological response. The Ca2+-dependent function of TMEM16A is highly regulated. Anions with higher permeability than Cl- facilitate V dependence by increasing the Ca2+ sensitivity, intracellular protons can replace Ca2+ and induce channel opening, and phosphatidylinositol 4,5-bisphosphate bound to four cytosolic sites likely maintains Ca2+ sensitivity. Additional regulation is afforded by cytosolic proteins, most likely by phosphorylation and protein-protein interaction mechanisms.
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Affiliation(s)
- Jorge Arreola
- Jorge Arreola, Physics Institute of Universidad Autónoma de San Luis Potosí. Av. Parque Chapultepec 1570, Privadas del Pedregal, 78295 San Luis Potosí, SLP., Mexico.
| | - Ana Elena López-Romero
- Jorge Arreola, Physics Institute of Universidad Autónoma de San Luis Potosí. Av. Parque Chapultepec 1570, Privadas del Pedregal, 78295 San Luis Potosí, SLP., Mexico
| | - Miriam Huerta
- Jorge Arreola, Physics Institute of Universidad Autónoma de San Luis Potosí. Av. Parque Chapultepec 1570, Privadas del Pedregal, 78295 San Luis Potosí, SLP., Mexico
| | - María Luisa Guzmán-Hernández
- Catedrática CONAHCYT, Department of Physiology and Biophysics, School of Medicine, Universidad Autónoma de San Luis Potosí. Ave. V. Carranza 2905, Los Filtros, San Luis Potosí, SLP 78210, Mexico
| | - Patricia Pérez-Cornejo
- Department of Physiology and Biophysics, School of Medicine, Universidad Autónoma de San Luis Potosí. Ave. V. Carranza 2905, Los Filtros, San Luis Potosí, SLP 78210, Mexico
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4
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Genovese M, Galietta LJV. Anoctamin pharmacology. Cell Calcium 2024; 121:102905. [PMID: 38788257 DOI: 10.1016/j.ceca.2024.102905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Revised: 05/07/2024] [Accepted: 05/09/2024] [Indexed: 05/26/2024]
Abstract
TMEM16 proteins, also known as anoctamins, are a family of ten membrane proteins with various tissue expression and subcellular localization. TMEM16A (anoctamin 1) is a plasma membrane protein that acts as a calcium-activated chloride channel. It is expressed in many types of epithelial cells, smooth muscle cells and some neurons. In airway epithelial cells, TMEM16A expression is particularly enhanced by inflammatory stimuli that also promote goblet cell metaplasia and mucus hypersecretion. Therefore, pharmacological modulation of TMEM16A could be beneficial to improve mucociliary clearance in chronic obstructive respiratory diseases. However, the correct approach to modulate TMEM16A activity (activation or inhibition) is still debated. Pharmacological inhibitors of TMEM16A could also be useful as anti-hypertensive agents given the TMEM16A role in smooth muscle contraction. In contrast to TMEM16A, TMEM16F (anoctamin 6) behaves as a calcium-activated phospholipid scramblase, responsible for the externalization of phosphatidylserine on cell surface. Inhibitors of TMEM16F could be useful as anti-coagulants and anti-viral agents. The role of other anoctamins as therapeutic targets is still unclear since their physiological role is still to be defined.
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Affiliation(s)
- Michele Genovese
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli (NA), Italy
| | - Luis J V Galietta
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli (NA), Italy; Department of Translational Medical Sciences (DISMET), University of Naples "Federico II", Italy.
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5
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Dibattista M, Pifferi S, Hernandez-Clavijo A, Menini A. The physiological roles of anoctamin2/TMEM16B and anoctamin1/TMEM16A in chemical senses. Cell Calcium 2024; 120:102889. [PMID: 38677213 DOI: 10.1016/j.ceca.2024.102889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 04/11/2024] [Accepted: 04/17/2024] [Indexed: 04/29/2024]
Abstract
Chemical senses allow animals to detect and discriminate a vast array of molecules. The olfactory system is responsible of the detection of small volatile molecules, while water dissolved molecules are detected by taste buds in the oral cavity. Moreover, many animals respond to signaling molecules such as pheromones and other semiochemicals through the vomeronasal organ. The peripheral organs dedicated to chemical detection convert chemical signals into perceivable information through the employment of diverse receptor types and the activation of multiple ion channels. Two ion channels, TMEM16B, also known as anoctamin2 (ANO2) and TMEM16A, or anoctamin1 (ANO1), encoding for Ca2+-activated Cl¯ channels, have been recently described playing critical roles in various cell types. This review aims to discuss the main properties of TMEM16A and TMEM16B-mediated currents and their physiological roles in chemical senses. In olfactory sensory neurons, TMEM16B contributes to amplify the odorant response, to modulate firing, response kinetics and adaptation. TMEM16A and TMEM16B shape the pattern of action potentials in vomeronasal sensory neurons increasing the interspike interval. In type I taste bud cells, TMEM16A is activated during paracrine signaling mediated by ATP. This review aims to shed light on the regulation of diverse signaling mechanisms and neuronal excitability mediated by Ca-activated Cl¯ channels, hinting at potential new roles for TMEM16A and TMEM16B in the chemical senses.
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Affiliation(s)
- Michele Dibattista
- Department of Translational Biomedicine and Neuroscience, University of Bari A. Moro, 70121 Bari, Italy
| | - Simone Pifferi
- Department of Experimental and Clinical Medicine, Università Politecnica delle Marche, 60126 Ancona, Italy.
| | - Andres Hernandez-Clavijo
- Department of Chemosensation, Institute for Biology II, RWTH Aachen University, 52074 Aachen, Germany
| | - Anna Menini
- Neurobiology Group, SISSA, Scuola Internazionale Superiore di Studi Avanzati, 34136 Trieste, Italy.
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6
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Arreola J, Pérez-Cornejo P, Segura-Covarrubias G, Corral-Fernández N, León-Aparicio D, Guzmán-Hernández ML. Function and Regulation of the Calcium-Activated Chloride Channel Anoctamin 1 (TMEM16A). Handb Exp Pharmacol 2024; 283:101-151. [PMID: 35768554 DOI: 10.1007/164_2022_592] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Various human tissues express the calcium-activated chloride channel Anoctamin 1 (ANO1), also known as TMEM16A. ANO1 allows the passive chloride flux that controls different physiological functions ranging from muscle contraction, fluid and hormone secretion, gastrointestinal motility, and electrical excitability. Overexpression of ANO1 is associated with pathological conditions such as hypertension and cancer. The molecular cloning of ANO1 has led to a surge in structural, functional, and physiological studies of the channel in several tissues. ANO1 is a homodimer channel harboring two pores - one in each monomer - that work independently. Each pore is activated by voltage-dependent binding of two intracellular calcium ions to a high-affinity-binding site. In addition, the binding of phosphatidylinositol 4,5-bisphosphate to sites scattered throughout the cytosolic side of the protein aids the calcium activation process. Furthermore, many pharmacological studies have established ANO1 as a target of promising compounds that could treat several illnesses. This chapter describes our current understanding of the physiological roles of ANO1 and its regulation under physiological conditions as well as new pharmacological compounds with potential therapeutic applications.
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Affiliation(s)
- Jorge Arreola
- Physics Institute, Universidad Autónoma de San Luis Potosí, San Luis Potosí, Mexico.
| | - Patricia Pérez-Cornejo
- Department of Physiology and Biophysics, School of Medicine of Universidad Autónoma de San Luis Potosí, San Luis Potosí, Mexico
| | - Guadalupe Segura-Covarrubias
- Physics Institute, Universidad Autónoma de San Luis Potosí, San Luis Potosí, Mexico
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH, USA
| | - Nancy Corral-Fernández
- Department of Physiology and Biophysics, School of Medicine of Universidad Autónoma de San Luis Potosí, San Luis Potosí, Mexico
| | - Daniel León-Aparicio
- Physics Institute, Universidad Autónoma de San Luis Potosí, San Luis Potosí, Mexico
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7
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Nguyen DM, Chen TY. Structure and Function of Calcium-Activated Chloride Channels and Phospholipid Scramblases in the TMEM16 Family. Handb Exp Pharmacol 2024; 283:153-180. [PMID: 35792944 DOI: 10.1007/164_2022_595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The transmembrane protein 16 (TMEM16) family consists of Ca2+-activated chloride channels and phospholipid scramblases. Ten mammalian TMEM16 proteins, TMEM16A-K (with no TMEM16I), and several non-mammalian TMEM16 proteins, such as afTMEM16 and nhTMEM16, have been discovered. All known TMEM16 proteins are homodimeric proteins containing two subunits. Each subunit consists of ten transmembrane helices with Ca2+-binding sites and a single ion-permeation/phospholipid transport pathway. The ion-permeation pathway and the phospholipid transport pathway of TMEM16 proteins have a wide intracellular vestibule, a narrow neck, and a smaller extracellular vestibule. Interestingly, the lining wall of the ion-permeation/phospholipid transport pathway may be formed, at least partially, by membrane phospholipids, though the degree of pore-wall forming by phospholipids likely varies among TMEM16 proteins. Thus, the biophysical properties and activation mechanisms of TMEM16 proteins could differ from each other accordingly. Here we review the current understanding of the structure and function of TMEM16 molecules.
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Affiliation(s)
- Dung Manh Nguyen
- Center for Neuroscience, University of California, Davis, CA, USA.
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA.
| | - Tsung-Yu Chen
- Department of Neurology, Center for Neuroscience, University of California, Davis, CA, USA.
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8
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Lam AKM, Dutzler R. Mechanistic basis of ligand efficacy in the calcium-activated chloride channel TMEM16A. EMBO J 2023; 42:e115030. [PMID: 37984335 PMCID: PMC10711664 DOI: 10.15252/embj.2023115030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 10/27/2023] [Accepted: 11/02/2023] [Indexed: 11/22/2023] Open
Abstract
Agonist binding in ligand-gated ion channels is coupled to structural rearrangements around the binding site, followed by the opening of the channel pore. In this process, agonist efficacy describes the equilibrium between open and closed conformations in a fully ligand-bound state. Calcium-activated chloride channels in the TMEM16 family are important sensors of intracellular calcium signals and are targets for pharmacological modulators, yet a mechanistic understanding of agonist efficacy has remained elusive. Using a combination of cryo-electron microscopy, electrophysiology, and autocorrelation analysis, we now show that agonist efficacy in the ligand-gated channel TMEM16A is dictated by the conformation of the pore-lining helix α6 around the Ca2+ -binding site. The closure of the binding site, which involves the formation of a π-helix below a hinge region in α6, appears to be coupled to the opening of the inner pore gate, thereby governing the channel's open probability and conductance. Our results provide a mechanism for agonist binding and efficacy and a structural basis for the design of potentiators and partial agonists in the TMEM16 family.
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Affiliation(s)
- Andy KM Lam
- Department of BiochemistryUniversity of ZurichZurichSwitzerland
| | - Raimund Dutzler
- Department of BiochemistryUniversity of ZurichZurichSwitzerland
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9
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Li S, Wang Z, Geng R, Zhang W, Wan H, Kang X, Guo S. TMEM16A ion channel: A novel target for cancer treatment. Life Sci 2023; 331:122034. [PMID: 37611692 DOI: 10.1016/j.lfs.2023.122034] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 08/13/2023] [Accepted: 08/18/2023] [Indexed: 08/25/2023]
Abstract
Cancer draws attention owing to the high morbidity and mortality. It is urgent to develop safe and effective cancer therapeutics. The calcium-activated chloride channel TMEM16A is widely distributed in various tissues and regulates physiological functions. TMEM16A is abnormally expressed in several cancers and associate with tumorigenesis, metastasis, and prognosis. Knockdown or inhibition of TMEM16A in cancer cells significantly inhibits cancer development. Therefore, TMEM16A is considered as a biomarker and therapeutic target for some cancers. This work reviews the cancers associated with TMEM16A. Then, the molecular mechanism of TMEM16A overexpression in cancer was analyzed, and the possible signal transduction mechanism of TMEM16A regulating cancer development was summarized. Finally, TMEM16A inhibitors with anticancer effect and their anticancer mechanism were concluded. We hope to provide new ideas for pharmacological studies on TMEM16A in cancer.
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Affiliation(s)
- Shuting Li
- School of Life Sciences, Hebei University, Baoding 071002, Hebei, China
| | - Zhichen Wang
- School of Life Sciences, Hebei University, Baoding 071002, Hebei, China
| | - Ruili Geng
- School of Life Sciences, Hebei University, Baoding 071002, Hebei, China
| | - Weiwei Zhang
- School of Basic Medical Sciences, Hebei University, Baoding 071002, Hebei, China
| | - Haifu Wan
- School of Life Sciences, Hebei University, Baoding 071002, Hebei, China; Institute of Life Sciences and Green Development, Hebei University, Baoding 071002, Hebei, China
| | - Xianjiang Kang
- School of Life Sciences, Hebei University, Baoding 071002, Hebei, China; Institute of Life Sciences and Green Development, Hebei University, Baoding 071002, Hebei, China.
| | - Shuai Guo
- School of Life Sciences, Hebei University, Baoding 071002, Hebei, China; Institute of Life Sciences and Green Development, Hebei University, Baoding 071002, Hebei, China.
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10
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Feng S, Puchades C, Ko J, Wu H, Chen Y, Figueroa EE, Gu S, Han TW, Ho B, Cheng T, Li J, Shoichet B, Jan YN, Cheng Y, Jan LY. Identification of a drug binding pocket in TMEM16F calcium-activated ion channel and lipid scramblase. Nat Commun 2023; 14:4874. [PMID: 37573365 PMCID: PMC10423226 DOI: 10.1038/s41467-023-40410-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2022] [Accepted: 07/23/2023] [Indexed: 08/14/2023] Open
Abstract
The dual functions of TMEM16F as Ca2+-activated ion channel and lipid scramblase raise intriguing questions regarding their molecular basis. Intrigued by the ability of the FDA-approved drug niclosamide to inhibit TMEM16F-dependent syncytia formation induced by SARS-CoV-2, we examined cryo-EM structures of TMEM16F with or without bound niclosamide or 1PBC, a known blocker of TMEM16A Ca2+-activated Cl- channel. Here, we report evidence for a lipid scrambling pathway along a groove harboring a lipid trail outside the ion permeation pore. This groove contains the binding pocket for niclosamide and 1PBC. Mutations of two residues in this groove specifically affect lipid scrambling. Whereas mutations of some residues in the binding pocket of niclosamide and 1PBC reduce their inhibition of TMEM16F-mediated Ca2+ influx and PS exposure, other mutations preferentially affect the ability of niclosamide and/or 1PBC to inhibit TMEM16F-mediated PS exposure, providing further support for separate pathways for ion permeation and lipid scrambling.
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Affiliation(s)
- Shengjie Feng
- Department of Physiology, University of California San Francisco (UCSF) School of Medicine, San Francisco, CA, USA
| | - Cristina Puchades
- Department of Biochemistry and Biophysics, University of California San Francisco (UCSF) School of Medicine, San Francisco, CA, USA
| | - Juyeon Ko
- Department of Physiology, University of California San Francisco (UCSF) School of Medicine, San Francisco, CA, USA
| | - Hao Wu
- Department of Biochemistry and Biophysics, University of California San Francisco (UCSF) School of Medicine, San Francisco, CA, USA
| | - Yifei Chen
- Howard Hughes Medical Institute; UCSF, San Francisco, CA, USA
| | - Eric E Figueroa
- Department of Physiology, University of California San Francisco (UCSF) School of Medicine, San Francisco, CA, USA
| | - Shuo Gu
- BioDuro-Sundia Inc., Irvine, CA, USA
| | - Tina W Han
- Department of Physiology, University of California San Francisco (UCSF) School of Medicine, San Francisco, CA, USA
- Dewpoint Therapeutics, Boston, MA, USA
| | - Brandon Ho
- Department of Physiology, University of California San Francisco (UCSF) School of Medicine, San Francisco, CA, USA
| | - Tong Cheng
- Howard Hughes Medical Institute; UCSF, San Francisco, CA, USA
| | - Junrui Li
- Department of Biochemistry and Biophysics, University of California San Francisco (UCSF) School of Medicine, San Francisco, CA, USA
| | - Brian Shoichet
- Department of Pharmaceutical Chemistry, University of California San Francisco (UCSF) School of Pharmacy, San Francisco, CA, USA
| | - Yuh Nung Jan
- Department of Physiology, University of California San Francisco (UCSF) School of Medicine, San Francisco, CA, USA
- Department of Biochemistry and Biophysics, University of California San Francisco (UCSF) School of Medicine, San Francisco, CA, USA
- Howard Hughes Medical Institute; UCSF, San Francisco, CA, USA
| | - Yifan Cheng
- Department of Biochemistry and Biophysics, University of California San Francisco (UCSF) School of Medicine, San Francisco, CA, USA.
- Howard Hughes Medical Institute; UCSF, San Francisco, CA, USA.
| | - Lily Yeh Jan
- Department of Physiology, University of California San Francisco (UCSF) School of Medicine, San Francisco, CA, USA.
- Department of Biochemistry and Biophysics, University of California San Francisco (UCSF) School of Medicine, San Francisco, CA, USA.
- Howard Hughes Medical Institute; UCSF, San Francisco, CA, USA.
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11
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Liang P, Wan YCS, Yu K, Hartzell HC, Yang H. Niclosamide potentiates TMEM16A and induces vasoconstriction. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.31.551400. [PMID: 37577682 PMCID: PMC10418162 DOI: 10.1101/2023.07.31.551400] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
The TMEM16A calcium-activated chloride channel is a promising therapeutic target for various diseases. Niclosamide, an anthelmintic medication, has been considered as a TMEM16A inhibitor for treating asthma and chronic obstructive pulmonary disease, but was recently found to possess broad-spectrum off-target effects. Here we show that, under physiological conditions, niclosamide acutely potentiates TMEM16A without having any inhibitory effect. Our computational and functional characterizations pinpoint a putative niclosamide binding site on the extracellular side of TMEM16A. Mutations in this site attenuate the potentiation. Moreover, niclosamide potentiates endogenous TMEM16A in vascular smooth muscle cells, triggers intracellular calcium increase, and constricts the murine mesenteric artery. Our findings advise caution when considering niclosamide as a TMEM16A inhibitor to treat diseases such as asthma, COPD, and hypertension. The identification of the putative niclosamide binding site provides insights into the mechanism of TMEM16A pharmacological modulation, shining light on developing specific TMEM16A modulators to treat human diseases.
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Affiliation(s)
- Pengfei Liang
- Department of Biochemistry, Duke University School of Medicine, NC 27710, USA
| | - Yui Chun S. Wan
- Department of Biochemistry, Duke University School of Medicine, NC 27710, USA
| | - Kuai Yu
- Department of Cell Biology, Emory University School of Medicine, GA 30322, USA
| | - H. Criss Hartzell
- Department of Cell Biology, Emory University School of Medicine, GA 30322, USA
| | - Huanghe Yang
- Department of Biochemistry, Duke University School of Medicine, NC 27710, USA
- Department of Neurobiology, Duke University School of Medicine, NC 27710, USA
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12
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Yuan L, Tang Y, Yin L, Lin X, Luo Z, Wang S, Li J, Liang P, Jiang B. The role of Transmembrane Protein 16A (TMEM16A) in pulmonary hypertension. Cardiovasc Pathol 2023; 65:107525. [PMID: 36781068 DOI: 10.1016/j.carpath.2023.107525] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 02/04/2023] [Accepted: 02/06/2023] [Indexed: 02/13/2023] Open
Abstract
Transmembrane protein 16A (TMEM16A), a member of the TMEM16 family, is the molecular basis of Ca2+-activated chloride channels (CaCCs) and is involved in a variety of physiological and pathological processes. Previous studies have focused more on respiratory-related diseases and tumors. However, recent studies have identified an important role for TMEM16A in cardiovascular diseases, especially in pulmonary hypertension. TMEM16A is expressed in both pulmonary artery smooth muscle cells and pulmonary artery endothelial cells and is involved in the development of pulmonary hypertension. This paper presents the structure and function of TMEM16A, the pathogenesis of pulmonary hypertension, and highlights the role and mechanism of TMEM16A in pulmonary hypertension, summarizing the controversies in this field and taking into account hypertension and portal hypertension, which have similar pathogenesis. It is hoped that the unique role of TMEM16A in pulmonary hypertension will be illustrated and provide ideas for research in this area.
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Affiliation(s)
- Ludong Yuan
- Department of Pathophysiology, Sepsis Translational Medicine Key Laboratory of Hunan Province, Xiangya School of Medicine, Central South University, Changsha, Hunan, China; National Medicine Functional Experimental Teaching Center, Central South University, Changsha, Hunan China
| | - Yuting Tang
- Department of Pathophysiology, Sepsis Translational Medicine Key Laboratory of Hunan Province, Xiangya School of Medicine, Central South University, Changsha, Hunan, China; National Medicine Functional Experimental Teaching Center, Central South University, Changsha, Hunan China
| | - Leijing Yin
- Department of Pathophysiology, Sepsis Translational Medicine Key Laboratory of Hunan Province, Xiangya School of Medicine, Central South University, Changsha, Hunan, China; National Medicine Functional Experimental Teaching Center, Central South University, Changsha, Hunan China
| | - Xiaofang Lin
- Department of Pathophysiology, Sepsis Translational Medicine Key Laboratory of Hunan Province, Xiangya School of Medicine, Central South University, Changsha, Hunan, China; National Medicine Functional Experimental Teaching Center, Central South University, Changsha, Hunan China
| | - Zhengyang Luo
- Department of Pathophysiology, Sepsis Translational Medicine Key Laboratory of Hunan Province, Xiangya School of Medicine, Central South University, Changsha, Hunan, China; National Medicine Functional Experimental Teaching Center, Central South University, Changsha, Hunan China
| | - Shuxin Wang
- Department of Pathophysiology, Sepsis Translational Medicine Key Laboratory of Hunan Province, Xiangya School of Medicine, Central South University, Changsha, Hunan, China; National Medicine Functional Experimental Teaching Center, Central South University, Changsha, Hunan China
| | - Jing Li
- Department of Pathophysiology, Sepsis Translational Medicine Key Laboratory of Hunan Province, Xiangya School of Medicine, Central South University, Changsha, Hunan, China; National Medicine Functional Experimental Teaching Center, Central South University, Changsha, Hunan China
| | - Pengfei Liang
- Department of Burns and Plastic Surgery, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Bimei Jiang
- Department of Pathophysiology, Sepsis Translational Medicine Key Laboratory of Hunan Province, Xiangya School of Medicine, Central South University, Changsha, Hunan, China; National Medicine Functional Experimental Teaching Center, Central South University, Changsha, Hunan China.
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13
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Ritt CL, de Souza JP, Barsukov MG, Yosinski S, Bazant MZ, Reed MA, Elimelech M. Thermodynamics of Charge Regulation during Ion Transport through Silica Nanochannels. ACS NANO 2022; 16:15249-15260. [PMID: 36075111 DOI: 10.1021/acsnano.2c06633] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Ion-surface interactions can alter the properties of nanopores and dictate nanofluidic transport in engineered and biological systems central to the water-energy nexus. The ion adsorption process, known as "charge regulation", is ion-specific and is dependent on the extent of confinement when the electric double layers (EDLs) between two charged surfaces overlap. A fundamental understanding of the mechanisms behind charge regulation remains lacking. Herein, we study the thermodynamics of charge regulation reactions in 20 nm SiO2 channels via conductance measurements at various concentrations and temperatures. The effective activation energies (Ea) for ion conductance at low concentrations (strong EDL overlap) are ∼2-fold higher than at high concentrations (no EDL overlap) for the electrolytes studied here: LiCl, NaCl, KCl, and CsCl. We find that Ea values measured at high concentrations result from the temperature dependence of viscosity and its influence on ion mobility, whereas Ea values measured at low concentrations result from the combined effects of ion mobility and the enthalpy of cation adsorption to the charged surface. Notably, the Ea for surface reactions increases from 7.03 kJ mol-1 for NaCl to 16.72 ± 0.48 kJ mol-1 for KCl, corresponding to a difference in surface charge of -8.2 to -0.8 mC m-2, respectively. We construct a charge regulation model to rationalize the cation-specific charge regulation behavior based on an adsorption equilibrium. Our findings show that temperature- and concentration-dependent conductance measurements can help indirectly probe the ion-surface interactions that govern transport and colloidal interactions at the nanoscale─representing a critical step forward in our understanding of charge regulation and adsorption phenomena under nanoconfinement.
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Affiliation(s)
- Cody L Ritt
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520-8286, United States
| | - J Pedro de Souza
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Michelle G Barsukov
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520-8286, United States
| | - Shari Yosinski
- Department of Electrical Engineering, Yale University, New Haven, Connecticut 06511, United States
| | - Martin Z Bazant
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Mathematics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Mark A Reed
- Department of Electrical Engineering, Yale University, New Haven, Connecticut 06511, United States
| | - Menachem Elimelech
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520-8286, United States
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14
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De Jesús-Pérez JJ, López-Romero AE, Posadas O, Segura-Covarrubias G, Aréchiga-Figueroa I, Gutiérrez-Medina B, Pérez-Cornejo P, Arreola J. Gating and anion selectivity are reciprocally regulated in TMEM16A (ANO1). J Gen Physiol 2022; 154:213275. [PMID: 35687042 PMCID: PMC9194859 DOI: 10.1085/jgp.202113027] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 05/23/2022] [Indexed: 02/03/2023] Open
Abstract
Numerous essential physiological processes depend on the TMEM16A-mediated Ca2+-activated chloride fluxes. Extensive structure-function studies have helped to elucidate the Ca2+ gating mechanism of TMEM16A, revealing a Ca2+-sensing element close to the anion pore that alters conduction. However, substrate selection and the substrate-gating relationship in TMEM16A remain less explored. Here, we study the gating-permeant anion relationship on mouse TMEM16A expressed in HEK 293 cells using electrophysiological recordings coupled with site-directed mutagenesis. We show that the apparent Ca2+ sensitivity of TMEM16A increased with highly permeant anions and SCN- mole fractions, likely by stabilizing bound Ca2+. Conversely, mutations at crucial gating elements, including the Ca2+-binding site 1, the transmembrane helix 6 (TM6), and the hydrophobic gate, impaired the anion permeability and selectivity of TMEM16A. Finally, we found that, unlike anion-selective wild-type channels, the voltage dependence of unselective TMEM16A mutant channels was less sensitive to SCN-. Therefore, our work identifies structural determinants of selectivity at the Ca2+ site, TM6, and hydrophobic gate and reveals a reciprocal regulation of gating and selectivity. We suggest that this regulation is essential to set ionic selectivity and the Ca2+ and voltage sensitivities in TMEM16A.
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Affiliation(s)
| | - Ana E. López-Romero
- Physics Institute, Universidad Autónoma de San Luis Potosí, San Luis Potosí, México
| | - Odalys Posadas
- Physics Institute, Universidad Autónoma de San Luis Potosí, San Luis Potosí, México
| | | | - Iván Aréchiga-Figueroa
- Consejo Nacional de Ciencia y Tecnología, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, México
| | - Braulio Gutiérrez-Medina
- Advanced Materials Division, Instituto Potosino de Investigación Científica y Tecnológica, San Luis Potosí, México
| | - Patricia Pérez-Cornejo
- Department of Physiology and Biophysics, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, México
| | - Jorge Arreola
- Physics Institute, Universidad Autónoma de San Luis Potosí, San Luis Potosí, México,Correspondence to Jorge Arreola:
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15
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Lam AKM, Rutz S, Dutzler R. Inhibition mechanism of the chloride channel TMEM16A by the pore blocker 1PBC. Nat Commun 2022; 13:2798. [PMID: 35589730 PMCID: PMC9120017 DOI: 10.1038/s41467-022-30479-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 04/29/2022] [Indexed: 11/09/2022] Open
Abstract
TMEM16A, a calcium-activated chloride channel involved in multiple cellular processes, is a proposed target for diseases such as hypertension, asthma, and cystic fibrosis. Despite these therapeutic promises, its pharmacology remains poorly understood. Here, we present a cryo-EM structure of TMEM16A in complex with the channel blocker 1PBC and a detailed functional analysis of its inhibition mechanism. A pocket located external to the neck region of the hourglass-shaped pore is responsible for open-channel block by 1PBC and presumably also by its structural analogs. The binding of the blocker stabilizes an open-like conformation of the channel that involves a rearrangement of several pore helices. The expansion of the outer pore enhances blocker sensitivity and enables 1PBC to bind at a site within the transmembrane electric field. Our results define the mechanism of inhibition and gating and will facilitate the design of new, potent TMEM16A modulators.
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Affiliation(s)
- Andy K M Lam
- Department of Biochemistry, University of Zurich, Winterthurer Str. 190, CH-8057, Zurich, Switzerland.
| | - Sonja Rutz
- Department of Biochemistry, University of Zurich, Winterthurer Str. 190, CH-8057, Zurich, Switzerland
| | - Raimund Dutzler
- Department of Biochemistry, University of Zurich, Winterthurer Str. 190, CH-8057, Zurich, Switzerland.
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16
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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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17
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Boccaccio A, Picco C, Di Zanni E, Scholz-Starke J. Phospholipid scrambling by a TMEM16 homolog of Arabidopsis thaliana. FEBS J 2021; 289:2578-2592. [PMID: 34775680 PMCID: PMC9299152 DOI: 10.1111/febs.16279] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 09/15/2021] [Accepted: 11/12/2021] [Indexed: 12/20/2022]
Abstract
Membrane asymmetry is important for cellular physiology and established by energy‐dependent unidirectional lipid translocases, which have diverse physiological functions in plants. By contrast, the role of phospholipid scrambling (PLS), the passive bidirectional lipid transfer leading to the break‐down of membrane asymmetry, is currently still unexplored. The Arabidopsis thaliana genome contains a single gene (At1g73020) with homology to the eukaryotic TMEM16 family of Ca2+‐activated phospholipid scramblases. Here, we investigated the protein function of this Arabidopsis homolog. Fluorescent AtTMEM16 fusions localized to the ER both in transiently expressing Arabidopsis protoplasts and HEK293 cells. A putative scrambling domain (SCRD) was identified on the basis of sequence conservation and conferred PLS to transfected HEK293 cells, when grafted into the backbone of the non‐scrambling plasma membrane‐localized TMEM16A chloride channel. Finally, AtTMEM16 ‘gain‐of‐function’ variants gave rise to cellular phenotypes typical of aberrant scramblase activity, which were reversed by the additional introduction of a ‘loss‐of‐function’ mutation into the SCRD. In conclusion, our data suggest AtTMEM16 works as an ER‐resident lipid scramblase in Arabidopsis.
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Affiliation(s)
- Anna Boccaccio
- Institute of Biophysics, Consiglio Nazionale delle Ricerche, Genova, Italy
| | - Cristiana Picco
- Institute of Biophysics, Consiglio Nazionale delle Ricerche, Genova, Italy
| | - Eleonora Di Zanni
- Institute of Biophysics, Consiglio Nazionale delle Ricerche, Genova, Italy
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18
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Abstract
TMEM16A Ca2+-activated chloride channels are involved in multiple cellular functions and are proposed targets for diseases such as hypertension, stroke, and cystic fibrosis. This therapeutic endeavor, however, suffers from paucity of selective and potent modulators. Here, exploiting a synthetic small molecule with a biphasic effect on the TMEM16A channel, anthracene-9-carboxylic acid (A9C), we shed light on sites of the channel amenable for pharmacological intervention. Mutant channels with the intracellular gate constitutively open were generated. These channels were entirely insensitive to extracellular A9C when intracellular Ca2+ was omitted. However, when physiological Ca2+ levels were reestablished, the mutants regained sensitivity to A9C. Thus, intracellular Ca2+ is mandatory for the channel response to an extracellular modulator. The underlying mechanism is a conformational change in the outer pore that enables A9C to enter the pore to reach its binding site. The explanation of this structural rearrangement highlights a critical site for pharmacological intervention and reveals an aspect of Ca2+ gating in the TMEM16A channel.
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19
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Henckels KA, Fong D, Phillips JE. Development of a QPatch-Automated Electrophysiology Assay for Identifying TMEM16A Small-Molecule Inhibitors. Assay Drug Dev Technol 2021; 18:134-147. [PMID: 32319819 PMCID: PMC7268545 DOI: 10.1089/adt.2019.962] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The calcium-activated chloride channel, TMEM16A, is involved in airway hydration and bronchoconstriction and is a promising target for respiratory disease. Drug development efforts around channels require an electrophysiology-based assay for identifying inhibitors or activators. TMEM16A has proven to be a difficult channel to record on automated electrophysiology platforms due to its propensity for rundown. We developed an automated, whole-cell, electrophysiology assay on the QPatch-48 to evaluate small-molecule inhibitors of TMEM16A. In this assay, currents remained stable for a duration of roughly 11 min, allowing for the cumulative addition of five concentrations of compounds and resulted in reproducible IC50s. The absence of rundown was likely due to a low internal free-calcium level of 250 nM, which was high enough to produce large currents, but also maintained the voltage dependence of the channel. Current amplitude averaged 6 nA using the single-hole QPlate and the channel maintained outward rectification throughout the recording. Known TMEM16A inhibitors were tested and their IC50s aligned with those reported in the literature using manual patch-clamp. Once established, this assay was used to validate novel TMEM16A inhibitors that were identified in our high-throughput fluorescent-based assay, as well as to assist in structure–activity relationship efforts by the chemists. Overall, we demonstrate an easy to operate, reproducible, automated electrophysiology assay using the QPatch-48 for TMEM16A drug development efforts.
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Affiliation(s)
- Kathryn A Henckels
- Department of Process Development, Amgen, Inc., Thousand Oaks, California, USA
| | - David Fong
- Department of Inflammation Discovery Research, Amgen, Inc., Thousand Oaks, California, USA
| | - Jonathan E Phillips
- Department of Inflammation Discovery Research, Amgen, Inc., Thousand Oaks, California, USA
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20
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Liu Y, Liu Z, Wang K. The Ca 2+-activated chloride channel ANO1/TMEM16A: An emerging therapeutic target for epithelium-originated diseases? Acta Pharm Sin B 2021; 11:1412-1433. [PMID: 34221860 PMCID: PMC8245819 DOI: 10.1016/j.apsb.2020.12.003] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 08/19/2020] [Accepted: 09/14/2020] [Indexed: 02/07/2023] Open
Abstract
Anoctamin 1 (ANO1) or TMEM16A gene encodes a member of Ca2+ activated Cl– channels (CaCCs) that are critical for physiological functions, such as epithelial secretion, smooth muscle contraction and sensory signal transduction. The attraction and interest in ANO1/TMEM16A arise from a decade long investigations that abnormal expression or dysfunction of ANO1 is involved in many pathological phenotypes and diseases, including asthma, neuropathic pain, hypertension and cancer. However, the lack of specific modulators of ANO1 has impeded the efforts to validate ANO1 as a therapeutic target. This review focuses on the recent progress made in understanding of the pathophysiological functions of CaCC ANO1 and the current modulators used as pharmacological tools, hopefully illustrating a broad spectrum of ANO1 channelopathy and a path forward for this target validation.
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Key Words
- ANO1
- ANO1, anoctamin-1
- ASM, airway smooth muscle
- Ang II, angiotensin II
- BBB, blood–brain barrier
- CAMK, Ca2+/calmodulin-dependent protein kinase
- CF, cystic fibrosis
- CFTR, cystic fibrosis transmembrane conductance regulator
- Ca2+-activated Cl– channels (CaCCs)
- CaCCinh-A01
- CaCCs, Ca2+ activated chloride channels
- Cancer
- Cystic fibrosis
- DRG, dorsal root ganglion
- Drug target
- EGFR, epidermal growth factor receptor
- ENaC, epithelial sodium channels
- ER, endoplasmic reticulum
- ESCC, esophageal squamous cell carcinoma
- FRT, fisher rat thyroid
- GI, gastrointestinal
- GIST, gastrointestinal stromal tumor
- GPCR, G-protein coupled receptor
- HNSCC, head and neck squamous cell carcinoma
- HTS, high-throughput screening
- ICC, interstitial cells of Cajal
- IPAH, idiopathic pulmonary arterial hypertension
- MAPK, mitogen-activated protein kinase
- NF-κB, nuclear factor κB
- PAH, pulmonary arterial hypertension
- PAR2, protease activated receptor 2
- PASMC, pulmonary artery smooth muscle cells
- PIP2, phosphatidylinositol 4,5-bisphosphate
- PKD, polycystic kidney disease
- T16Ainh-A01
- TGF-β, transforming growth factor-β
- TMEM16A
- VGCC, voltage gated calcium channel
- VRAC, volume regulated anion channel
- VSMC, vascular smooth muscle cells
- YFP, yellow fluorescent protein
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Affiliation(s)
- Yani Liu
- Department of Pharmacology, School of Pharmacy, Qingdao University Medical College, Qingdao 266073, China
- Institute of Innovative Drugs, Qingdao University, Qingdao 266021, China
| | - Zongtao Liu
- Department of Clinical Laboratory, Qingdao Third People's Hospital, Qingdao 266041, China
| | - KeWei Wang
- Department of Pharmacology, School of Pharmacy, Qingdao University Medical College, Qingdao 266073, China
- Institute of Innovative Drugs, Qingdao University, Qingdao 266021, China
- Corresponding authors.
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21
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Petersen OH, Gerasimenko JV, Gerasimenko OV, Gryshchenko O, Peng S. The roles of calcium and ATP in the physiology and pathology of the exocrine pancreas. Physiol Rev 2021; 101:1691-1744. [PMID: 33949875 DOI: 10.1152/physrev.00003.2021] [Citation(s) in RCA: 61] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
This review deals with the roles of calcium ions and ATP in the control of the normal functions of the different cell types in the exocrine pancreas as well as the roles of these molecules in the pathophysiology of acute pancreatitis. Repetitive rises in the local cytosolic calcium ion concentration in the apical part of the acinar cells not only activate exocytosis but also, via an increase in the intramitochondrial calcium ion concentration, stimulate the ATP formation that is needed to fuel the energy-requiring secretion process. However, intracellular calcium overload, resulting in a global sustained elevation of the cytosolic calcium ion concentration, has the opposite effect of decreasing mitochondrial ATP production, and this initiates processes that lead to necrosis. In the last few years it has become possible to image calcium signaling events simultaneously in acinar, stellate, and immune cells in intact lobules of the exocrine pancreas. This has disclosed processes by which these cells interact with each other, particularly in relation to the initiation and development of acute pancreatitis. By unraveling the molecular mechanisms underlying this disease, several promising therapeutic intervention sites have been identified. This provides hope that we may soon be able to effectively treat this often fatal disease.
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Affiliation(s)
- Ole H Petersen
- School of Biosciences, Cardiff University, Cardiff, United Kingdom
| | | | | | | | - Shuang Peng
- Department of Pathophysiology, Key Laboratory of State Administration of Traditional Chinese Medicine of the People's Republic of China, School of Medicine, Jinan University, Guangzhou, Guangdong, People's Republic of China
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22
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The Groovy TMEM16 Family: Molecular Mechanisms of Lipid Scrambling and Ion Conduction. J Mol Biol 2021; 433:166941. [PMID: 33741412 DOI: 10.1016/j.jmb.2021.166941] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 03/09/2021] [Accepted: 03/09/2021] [Indexed: 12/28/2022]
Abstract
The TMEM16 family of membrane proteins displays a remarkable functional dichotomy - while some family members function as Ca2+-activated anion channels, the majority of characterized TMEM16 homologs are Ca2+-activated lipid scramblases, which catalyze the exchange of phospholipids between the two membrane leaflets. Furthermore, some TMEM16 scramblases can also function as channels. Due to their involvement in important physiological processes, the family has been actively studied ever since their molecular identity was unraveled. In this review, we will summarize the recent advances in the field and how they influenced our view of TMEM16 family function and evolution. Structural, functional and computational studies reveal how relatively small rearrangements in the permeation pathway are responsible for the observed functional duality: while TMEM16 scramblases can adopt both ion- and lipid conductive conformations, TMEM16 channels can only populate the former. Recent data further provides the molecular details of a stepwise activation mechanism, which is initiated by Ca2+ binding and modulated by various cellular factors, including lipids. TMEM16 function and the surrounding membrane properties are inextricably intertwined, with the protein inducing bilayer deformations associated with scrambling, while the surrounding lipids modulate TMEM16 conformation and activity.
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23
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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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24
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Jia Z, Chen J. Specific PIP 2 binding promotes calcium activation of TMEM16A chloride channels. Commun Biol 2021; 4:259. [PMID: 33637964 PMCID: PMC7910439 DOI: 10.1038/s42003-021-01782-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 02/01/2021] [Indexed: 11/09/2022] Open
Abstract
TMEM16A is a widely expressed Ca2+-activated Cl− channel that regulates crucial physiological functions including fluid secretion, neuronal excitability, and smooth muscle contraction. There is a critical need to understand the molecular mechanisms of TMEM16A gating and regulation. However, high-resolution TMEM16A structures have failed to reveal an activated state with an unobstructed permeation pathway even with saturating Ca2+. This has been attributed to the requirement of PIP2 for preventing TMEM16A desensitization. Here, atomistic simulations show that specific binding of PIP2 to TMEM16A can lead to spontaneous opening of the permeation pathway in the Ca2+-bound state. The predicted activated state is highly consistent with a wide range of mutagenesis and functional data. It yields a maximal Cl− conductance of ~1 pS, similar to experimental estimates, and recapitulates the selectivity of larger SCN− over Cl−. The resulting molecular mechanism of activation provides a basis for understanding the interplay of multiple signals in controlling TMEM16A channel function. Chen and Jia investigate the synergistic regulating role of Ca2+ binding and the signaling lipid PIP2 in TMEM16A channel gating. Their study is significant as it provides new insights into the activated state of TMEM16A and highlights an example of functional importance of lipids in regulating membrane-associated proteins.
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Affiliation(s)
- Zhiguang Jia
- Department of Chemistry, University of Massachusetts, Amherst, MA, USA.,Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA, USA
| | - Jianhan Chen
- Department of Chemistry, University of Massachusetts, Amherst, MA, USA. .,Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA, USA.
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25
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Le SC, Yang H. Structure-Function of TMEM16 Ion Channels and Lipid Scramblases. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1349:87-109. [PMID: 35138612 PMCID: PMC11020148 DOI: 10.1007/978-981-16-4254-8_6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The TMEM16 protein family comprises two novel classes of structurally conserved but functionally distinct membrane transporters that function as Ca2+-dependent Cl- channels (CaCCs) or dual functional Ca2+-dependent ion channels and phospholipid scramblases. Extensive functional and structural studies have advanced our understanding of TMEM16 molecular mechanisms and physiological functions. TMEM16A and TMEM16B CaCCs control transepithelial fluid transport, smooth muscle contraction, and neuronal excitability, whereas TMEM16 phospholipid scramblases mediate the flip-flop of phospholipids across the membrane to allow phosphatidylserine externalization, which is essential in a plethora of important processes such as blood coagulation, bone development, and viral and cell fusion. In this chapter, we summarize the major methods in studying TMEM16 ion channels and scramblases and then focus on the current mechanistic understanding of TMEM16 Ca2+- and voltage-dependent channel gating as well as their ion and phospholipid permeation.
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Affiliation(s)
- Son C Le
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
| | - Huanghe Yang
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA.
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26
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An Additional Ca 2+ Binding Site Allosterically Controls TMEM16A Activation. Cell Rep 2020; 33:108570. [PMID: 33378669 PMCID: PMC7786149 DOI: 10.1016/j.celrep.2020.108570] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 08/18/2020] [Accepted: 12/08/2020] [Indexed: 12/13/2022] Open
Abstract
Calcium (Ca2+) is the primary stimulus for transmembrane protein 16 (TMEM16) Ca2+-activated chloride channels and phospholipid scramblases, which regulate important physiological processes ranging from smooth muscle contraction to blood coagulation and tumor progression. Binding of intracellular Ca2+ to two highly conserved orthosteric binding sites in transmembrane helices (TMs) 6-8 efficiently opens the permeation pathway formed by TMs 3-7. Recent structures of TMEM16K and TMEM16F scramblases revealed an additional Ca2+ binding site between TM2 and TM10, whose functional relevance remains unknown. Here, we report that Ca2+ binds with high affinity to the equivalent third Ca2+ site in TMEM16A to enhance channel activation. Our cadmium (Cd2+) metal bridging experiments reveal that the third Ca2+ site's conformational states can profoundly influence TMEM16A's opening. Our study thus confirms the existence of a third Ca2+ site in TMEM16A, defines its functional importance in channel gating, and provides insight into a long-range allosteric gating mechanism of TMEM16 channels and scramblases.
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Dulin NO. Calcium-Activated Chloride Channel ANO1/TMEM16A: Regulation of Expression and Signaling. Front Physiol 2020; 11:590262. [PMID: 33250781 PMCID: PMC7674831 DOI: 10.3389/fphys.2020.590262] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 10/13/2020] [Indexed: 01/11/2023] Open
Abstract
Anoctamin-1 (ANO1), also known as TMEM16A, is the most studied member of anoctamin family of calcium-activated chloride channels with diverse cellular functions. ANO1 controls multiple cell functions including cell proliferation, survival, migration, contraction, secretion, and neuronal excitation. This review summarizes the current knowledge of the cellular mechanisms governing the regulation of ANO1 expression and of ANO1-mediated intracellular signaling. This includes the stimuli and mechanisms controlling ANO1 expression, agonists and processes that activate ANO1, and signal transduction mediated by ANO1. The major conclusion is that this field is poorly understood, remains highly controversial, and requires extensive and rigorous further investigation.
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Affiliation(s)
- Nickolai O Dulin
- Department of Medicine, The University of Chicago, Chicago, IL, United States
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28
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Shi S, Pang C, Guo S, Chen Y, Ma B, Qu C, Ji Q, An H. Recent progress in structural studies on TMEM16A channel. Comput Struct Biotechnol J 2020; 18:714-722. [PMID: 32257055 PMCID: PMC7118279 DOI: 10.1016/j.csbj.2020.03.015] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Revised: 03/12/2020] [Accepted: 03/13/2020] [Indexed: 11/26/2022] Open
Abstract
The calcium-activated chloride channel, also known as TMEM16A, shows both calcium and membrane potential dependent activation. The channel is expressed broadly and contributes to a variety of physiological processes, and it is expected to be a target for the treatment of diseases such as hypertension, pain, cystic fibrosis and lung cancer. A thorough understanding of the structural characteristics of TMEM16A is important to reveal its physiological and pathological roles. Recent studies have released several Cryo-EM structures of the channel, revealed the structural basis and mechanism of the gating of the channel. This review focused on the understandings of the structural basis and molecular mechanism of the gating and permeation of TMEM16A channel, which will provide important basis for the development of drugs targeting TMEM16A.
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Affiliation(s)
- Sai Shi
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Hebei University of Technology, Tianjin 300401, China.,Key Laboratory of Electromagnetic Field and Electrical Apparatus Reliability of Hebei Province, Hebei University of Technology, Tianjin 300401, China.,Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Science, Hebei University of Technology, Tianjin, 300401, China
| | - Chunli Pang
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Science, Hebei University of Technology, Tianjin, 300401, China
| | - Shuai Guo
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Hebei University of Technology, Tianjin 300401, China.,Key Laboratory of Electromagnetic Field and Electrical Apparatus Reliability of Hebei Province, Hebei University of Technology, Tianjin 300401, China.,Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Science, Hebei University of Technology, Tianjin, 300401, China
| | - Yafei Chen
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Science, Hebei University of Technology, Tianjin, 300401, China
| | - Biao Ma
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Hebei University of Technology, Tianjin 300401, China.,Key Laboratory of Electromagnetic Field and Electrical Apparatus Reliability of Hebei Province, Hebei University of Technology, Tianjin 300401, China.,Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Science, Hebei University of Technology, Tianjin, 300401, China
| | - Chang Qu
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Hebei University of Technology, Tianjin 300401, China.,Key Laboratory of Electromagnetic Field and Electrical Apparatus Reliability of Hebei Province, Hebei University of Technology, Tianjin 300401, China.,Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Science, Hebei University of Technology, Tianjin, 300401, China
| | - Qiushuang Ji
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Science, Hebei University of Technology, Tianjin, 300401, China
| | - Hailong An
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Hebei University of Technology, Tianjin 300401, China.,Key Laboratory of Electromagnetic Field and Electrical Apparatus Reliability of Hebei Province, Hebei University of Technology, Tianjin 300401, China.,Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Science, Hebei University of Technology, Tianjin, 300401, China
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29
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Khelashvili G, Cheng X, Falzone ME, Doktorova M, Accardi A, Weinstein H. Membrane lipids are both the substrates and a mechanistically responsive environment of TMEM16 scramblase proteins. J Comput Chem 2020; 41:538-551. [PMID: 31750558 PMCID: PMC7261202 DOI: 10.1002/jcc.26105] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 09/04/2019] [Accepted: 10/17/2019] [Indexed: 12/21/2022]
Abstract
Recent discoveries about functional mechanisms of proteins in the TMEM16 family of phospholipid scramblases have illuminated the dual role of the membrane as both the substrate and a mechanistically responsive environment in the wide range of physiological processes and genetic disorders in which they are implicated. This is highlighted in the review of recent findings from our collaborative investigations of molecular mechanisms of TMEM16 scramblases that emerged from iterative functional, structural, and computational experimentation. In the context of this review, we present new MD simulations and trajectory analyses motivated by the fact that new structural information about the TMEM16 scramblases is emerging from cryo-EM determinations in lipid nanodiscs. Because the functional environment of these proteins in in vivo and in in vitro is closer to flat membranes, we studied comparatively the responses of the membrane to the TMEM16 proteins in flat membranes and nanodiscs. We find that bilayer shapes in the nanodiscs are very different from those observed in the flat membrane systems, but the function-related slanting of the membrane observed at the nhTMEM16 boundary with the protein is similar in the nanodiscs and in the flat bilayers. This changes, however, in the bilayer composed of longer-tail lipids, which is thicker near the phospholipid translocation pathway, which may reflect an enhanced tendency of the long tails to penetrate the pathway and create, as shown previously, a nonconductive environment. These findings support the correspondence between the mechanistic involvement of the lipid environment in the flat membranes, and the nanodiscs. © 2019 Wiley Periodicals, Inc.
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Affiliation(s)
- George Khelashvili
- Department of Physiology and Biophysics, Weill Cornell Medical College of Cornell University, New York, New York, 10065
- Institute for Computational Biomedicine, Weill Cornell Medical College of Cornell University, New York, New York, 10065
| | - Xiaolu Cheng
- Department of Physiology and Biophysics, Weill Cornell Medical College of Cornell University, New York, New York, 10065
| | - Maria E Falzone
- Department of Biochemistry, Weill Cornell Medical College of Cornell University, New York, New York, 10065
| | - Milka Doktorova
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, Texas, 77030
| | - Alessio Accardi
- Department of Physiology and Biophysics, Weill Cornell Medical College of Cornell University, New York, New York, 10065
- Department of Biochemistry, Weill Cornell Medical College of Cornell University, New York, New York, 10065
- Department of Anesthesiology, Weill Cornell Medical College of Cornell University, New York, New York, 10065
| | - Harel Weinstein
- Department of Physiology and Biophysics, Weill Cornell Medical College of Cornell University, New York, New York, 10065
- Institute for Computational Biomedicine, Weill Cornell Medical College of Cornell University, New York, New York, 10065
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30
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Li KX, He M, Ye W, Simms J, Gill M, Xiang X, Jan YN, Jan LY. TMEM16B regulates anxiety-related behavior and GABAergic neuronal signaling in the central lateral amygdala. eLife 2019; 8:47106. [PMID: 31482844 PMCID: PMC6746550 DOI: 10.7554/elife.47106] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2019] [Accepted: 09/04/2019] [Indexed: 12/17/2022] Open
Abstract
TMEM16B (ANO2) is the Ca2+-activated chloride channel expressed in multiple brain regions, including the amygdala. Here we report that Ano2 knockout mice exhibit impaired anxiety-related behaviors and context-independent fear memory, thus implicating TMEM16B in anxiety modulation. We found that TMEM16B is expressed in somatostatin-positive (SOM+) GABAergic neurons of the central lateral amygdala (CeL), and its activity modulates action potential duration and inhibitory postsynaptic current (IPSC). We further provide evidence for TMEM16B actions not only in the soma but also in the presynaptic nerve terminals of GABAergic neurons. Our study reveals an intriguing role for TMEM16B in context-independent but not context-dependent fear memory, and supports the notion that dysfunction of the amygdala contributes to anxiety-related behaviors.
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Affiliation(s)
- Ke-Xin Li
- Department of Physiology, University of California, San Francisco, San Francisco, United States.,Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States.,Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, United States
| | - Mu He
- Department of Physiology, University of California, San Francisco, San Francisco, United States.,Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States.,Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, United States
| | - Wenlei Ye
- Department of Physiology, University of California, San Francisco, San Francisco, United States.,Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States.,Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, United States
| | - Jeffrey Simms
- Gladstone Institute of Neurological Disease, San Francisco, United States
| | - Michael Gill
- Gladstone Institute of Neurological Disease, San Francisco, United States
| | - Xuaner Xiang
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, San Francisco, United States
| | - Yuh Nung Jan
- Department of Physiology, University of California, San Francisco, San Francisco, United States.,Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States.,Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, United States
| | - Lily Yeh Jan
- Department of Physiology, University of California, San Francisco, San Francisco, United States.,Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States.,Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, United States
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31
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Crottès D, Jan LY. The multifaceted role of TMEM16A in cancer. Cell Calcium 2019; 82:102050. [PMID: 31279157 PMCID: PMC6711484 DOI: 10.1016/j.ceca.2019.06.004] [Citation(s) in RCA: 76] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Revised: 06/13/2019] [Accepted: 06/13/2019] [Indexed: 12/30/2022]
Abstract
The calcium-activated chloride channel TMEM16A is intimately linked to cancers. Over decades, TMEM16A over-expression and contribution to prognosis have been widely studied for multiple cancers strengthening the idea that TMEM16A could be a valuable biomarker and a promising therapeutic target. Surprisingly, from the survey of the literature, it appears that TMEM16A has been involved in multiple cancer-related functions and a large number of molecular targets of TMEM16A have been proposed. Thus, TMEM16A appears to be an ion channel with a multifaceted role in cancers. In this review, we summarize the latest development regarding TMEM16A contribution to cancers. We will survey TMEM16A contribution in cancer prognosis, the origins of its over-expression in cancer cells, the multiple biological functions and molecular pathways regulated by TMEM16A. Then, we will consider the question regarding the molecular mechanism of TMEM16A in cancers and the possible basis for the multifaceted role of TMEM16A in cancers.
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Affiliation(s)
- David Crottès
- Departments of Physiology, Biochemistry, and Biophysics, Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA, 94143, USA
| | - Lily Yeh Jan
- Departments of Physiology, Biochemistry, and Biophysics, Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA, 94143, USA.
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32
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Le SC, Jia Z, Chen J, Yang H. Molecular basis of PIP 2-dependent regulation of the Ca 2+-activated chloride channel TMEM16A. Nat Commun 2019; 10:3769. [PMID: 31434906 PMCID: PMC6704070 DOI: 10.1038/s41467-019-11784-8] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 08/02/2019] [Indexed: 11/20/2022] Open
Abstract
The calcium-activated chloride channel (CaCC) TMEM16A plays crucial roles in regulating neuronal excitability, smooth muscle contraction, fluid secretion and gut motility. While opening of TMEM16A requires binding of intracellular Ca2+, prolonged Ca2+-dependent activation results in channel desensitization or rundown, the mechanism of which is unclear. Here we show that phosphatidylinositol (4,5)-bisphosphate (PIP2) regulates TMEM16A channel activation and desensitization via binding to a putative binding site at the cytosolic interface of transmembrane segments (TMs) 3-5. We further demonstrate that the ion-conducting pore of TMEM16A is constituted of two functionally distinct modules: a Ca2+-binding module formed by TMs 6-8 and a PIP2-binding regulatory module formed by TMs 3-5, which mediate channel activation and desensitization, respectively. PIP2 dissociation from the regulatory module results in ion-conducting pore collapse and subsequent channel desensitization. Our findings thus provide key insights into the mechanistic understanding of TMEM16 channel gating and lipid-dependent regulation.
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Affiliation(s)
- Son C Le
- Department of Biochemistry, Duke University Medical Center, Durham, NC, USA
| | - Zhiguang Jia
- Department of Chemistry, University of Massachusetts, Amherst, MA, USA
| | - Jianhan Chen
- Department of Chemistry, University of Massachusetts, Amherst, MA, USA
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA, USA
| | - Huanghe Yang
- Department of Biochemistry, Duke University Medical Center, Durham, NC, USA.
- Department of Neurobiology, Duke University Medical Center, Durham, NC, USA.
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33
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Magacz M, Kędziora K, Sapa J, Krzyściak W. The Significance of Lactoperoxidase System in Oral Health: Application and Efficacy in Oral Hygiene Products. Int J Mol Sci 2019; 20:ijms20061443. [PMID: 30901933 PMCID: PMC6472183 DOI: 10.3390/ijms20061443] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 03/13/2019] [Accepted: 03/18/2019] [Indexed: 12/13/2022] Open
Abstract
Lactoperoxidase (LPO) present in saliva are an important element of the nonspecific immune response involved in maintaining oral health. The main role of this enzyme is to oxidize salivary thiocyanate ions (SCN-) in the presence of hydrogen peroxide (H₂O₂) to products that exhibit antimicrobial activity. LPO derived from bovine milk has found an application in food, cosmetics, and medical industries due to its structural and functional similarity to the human enzyme. Oral hygiene products enriched with the LPO system constitute an alternative to the classic fluoride caries prophylaxis. This review describes the physiological role of human salivary lactoperoxidase and compares the results of clinical trials and in vitro studies of LPO alone and complex dentifrices enriched with bovine LPO. The role of reactivators and inhibitors of LPO is discussed together with the possibility of using nanoparticles to increase the stabilization and activity of this enzyme.
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Affiliation(s)
- Marcin Magacz
- Department of Medical Diagnostics, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, 30-688 Kraków, Poland.
| | - Karolina Kędziora
- Department of Medical Diagnostics, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, 30-688 Kraków, Poland.
| | - Jacek Sapa
- Department of Pharmacodynamics, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, 30-688 Kraków, Poland.
| | - Wirginia Krzyściak
- Department of Medical Diagnostics, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, 30-688 Kraków, Poland.
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34
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Miner K, Labitzke K, Liu B, Wang P, Henckels K, Gaida K, Elliott R, Chen JJ, Liu L, Leith A, Trueblood E, Hensley K, Xia XZ, Homann O, Bennett B, Fiorino M, Whoriskey J, Yu G, Escobar S, Wong M, Born TL, Budelsky A, Comeau M, Smith D, Phillips J, Johnston JA, McGivern JG, Weikl K, Powers D, Kunzelmann K, Mohn D, Hochheimer A, Sullivan JK. Drug Repurposing: The Anthelmintics Niclosamide and Nitazoxanide Are Potent TMEM16A Antagonists That Fully Bronchodilate Airways. Front Pharmacol 2019; 10:51. [PMID: 30837866 PMCID: PMC6382696 DOI: 10.3389/fphar.2019.00051] [Citation(s) in RCA: 87] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Accepted: 01/18/2019] [Indexed: 01/21/2023] Open
Abstract
There is an unmet need in severe asthma where approximately 40% of patients exhibit poor β-agonist responsiveness, suffer daily symptoms and show frequent exacerbations. Antagonists of the Ca2+-activated Cl- channel, TMEM16A, offers a new mechanism to bronchodilate airways and block the multiple contractiles operating in severe disease. To identify TMEM16A antagonists we screened a library of ∼580,000 compounds. The anthelmintics niclosamide, nitazoxanide, and related compounds were identified as potent TMEM16A antagonists that blocked airway smooth muscle depolarization and contraction. To evaluate whether TMEM16A antagonists resist use- and inflammatory-desensitization pathways limiting β-agonist action, we tested their efficacy under harsh conditions using maximally contracted airways or airways pretreated with a cytokine cocktail. Stunningly, TMEM16A antagonists fully bronchodilated airways, while the β-agonist isoproterenol showed only partial effects. Thus, antagonists of TMEM16A and repositioning of niclosamide and nitazoxanide represent an important additional treatment for patients with severe asthma and COPD that is poorly controlled with existing therapies. It is of note that drug repurposing has also attracted wide interest in niclosamide and nitazoxanide as a new treatment for cancer and infectious disease. For the first time we identify TMEM16A as a molecular target for these drugs and thus provide fresh insights into their mechanism for the treatment of these disorders in addition to respiratory disease.
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Affiliation(s)
- Kent Miner
- Department of Inflammation Research, Amgen Inc., Thousand Oaks, CA, United States
| | - Katja Labitzke
- Department of Therapeutic Discovery, Amgen Inc., Regensburg, Germany
| | - Benxian Liu
- Department of Inflammation Research, Amgen Inc., Thousand Oaks, CA, United States
| | - Paul Wang
- Department of Therapeutic Discovery, Amgen Inc., Thousand Oaks, CA, United States
| | - Kathryn Henckels
- Department of Inflammation Research, Amgen Inc., Thousand Oaks, CA, United States
| | - Kevin Gaida
- Department of Inflammation Research, Amgen Inc., Thousand Oaks, CA, United States
| | - Robin Elliott
- Department of Inflammation Research, Amgen Inc., Thousand Oaks, CA, United States
| | - Jian Jeffrey Chen
- Department of Medicinal Chemistry, Amgen Inc., Thousand Oaks, CA, United States
| | - Longbin Liu
- Department of Medicinal Chemistry, Amgen Inc., Thousand Oaks, CA, United States
| | - Anh Leith
- Department of Inflammation Research, Amgen Inc., Seattle, WA, United States
| | - Esther Trueblood
- Department of Comparative Biology and Safety Sciences, Amgen Inc., Seattle, WA, United States
- Department of Comparative Biology and Safety Sciences, Amgen Inc., Thousand Oaks, CA, United States
- Department of Comparative Biology and Safety Sciences, Amgen Inc., South San Francisco, CA, United States
| | - Kelly Hensley
- Department of Comparative Biology and Safety Sciences, Amgen Inc., Seattle, WA, United States
- Department of Comparative Biology and Safety Sciences, Amgen Inc., Thousand Oaks, CA, United States
- Department of Comparative Biology and Safety Sciences, Amgen Inc., South San Francisco, CA, United States
| | - Xing-Zhong Xia
- Department of Inflammation Research, Amgen Inc., Thousand Oaks, CA, United States
| | - Oliver Homann
- Genome Analysis Unit, Amgen Inc., South San Francisco, CA, United States
| | - Brian Bennett
- Department of Inflammation Research, Amgen Inc., Thousand Oaks, CA, United States
| | - Mike Fiorino
- Department of Inflammation Research, Amgen Inc., Thousand Oaks, CA, United States
| | - John Whoriskey
- Department of Inflammation Research, Amgen Inc., Thousand Oaks, CA, United States
| | - Gang Yu
- Department of Inflammation Research, Amgen Inc., Thousand Oaks, CA, United States
| | - Sabine Escobar
- Department of Inflammation Research, Amgen Inc., Seattle, WA, United States
| | - Min Wong
- Department of Inflammation Research, Amgen Inc., Thousand Oaks, CA, United States
| | - Teresa L. Born
- Department of Inflammation Research, Amgen Inc., Seattle, WA, United States
| | - Alison Budelsky
- Department of Inflammation Research, Amgen Inc., Seattle, WA, United States
| | - Mike Comeau
- Department of Inflammation Research, Amgen Inc., Seattle, WA, United States
| | - Dirk Smith
- Department of Inflammation Research, Amgen Inc., Seattle, WA, United States
| | - Jonathan Phillips
- Department of Inflammation Research, Amgen Inc., Thousand Oaks, CA, United States
| | - James A. Johnston
- Department of Inflammation Research, Amgen Inc., Thousand Oaks, CA, United States
| | - Joseph G. McGivern
- Department of Therapeutic Discovery, Amgen Inc., Thousand Oaks, CA, United States
| | - Kerstin Weikl
- Department of Therapeutic Discovery, Amgen Inc., Regensburg, Germany
| | - David Powers
- Department of Therapeutic Discovery, Amgen Inc., Thousand Oaks, CA, United States
| | - Karl Kunzelmann
- Institut für Physiologie, Universität Regensburg, Regensburg, Germany
| | - Deanna Mohn
- Department of Inflammation Research, Amgen Inc., Thousand Oaks, CA, United States
| | | | - John K. Sullivan
- Department of Inflammation Research, Amgen Inc., Thousand Oaks, CA, United States
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35
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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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36
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Cao X, Pattnaik BR, Hughes BA. Mouse retinal pigment epithelial cells exhibit a thiocyanate-selective conductance. Am J Physiol Cell Physiol 2018; 315:C457-C473. [PMID: 29874109 DOI: 10.1152/ajpcell.00231.2017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The basolateral membrane anion conductance of the retinal pigment epithelium (RPE) is a key component of the transepithelial Cl- transport pathway. Although multiple Cl- channels have been found to be expressed in the RPE, the components of the resting Cl- conductance have not been identified. In this study, we used the patch-clamp method to characterize the ion selectivity of the anion conductance in isolated mouse RPE cells and in excised patches of RPE basolateral and apical membranes. Relative permeabilities ( PA/ PCl) calculated from reversal potentials measured in intact cells under bi-ionic conditions were as follows: SCN- >> ClO4- > [Formula: see text] > I- > Br- > Cl- >> gluconate. Relative conductances ( GA/ GCl) followed a similar trend of SCN- >> ClO4- > [Formula: see text] > I- > Br- ≈Cl- >> gluconate. Whole cell currents were highly time-dependent in 10 mM external SCN-, reflecting collapse of the electrochemical potential gradient due to SCN- accumulation or depletion intracellularly. When the membrane potential was held at -120 mV to minimize SCN- accumulation in cells exposed to 10 mM SCN-, the instantaneous current reversed at -90 mV, revealing that PSCN/ PCl is approximately 500. Macroscopic current recordings from outside-out patches demonstrated that both the basolateral and apical membranes exhibit SCN- conductances, with the basolateral membrane having a larger SCN- current density and higher relative permeability for SCN-. Our results suggest that the RPE basolateral and apical membranes contain previously unappreciated anion channels or electrogenic transporters that may mediate the transmembrane fluxes of SCN- and Cl-.
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Affiliation(s)
- Xu Cao
- Department of Ophthalmology and Visual Sciences, University of Michigan , Ann Arbor, Michigan
| | - Bikash R Pattnaik
- Department of Ophthalmology and Visual Sciences, University of Michigan , Ann Arbor, Michigan
| | - Bret A Hughes
- Department of Ophthalmology and Visual Sciences, University of Michigan , Ann Arbor, Michigan.,Department of Molecular and Integrative Physiology, University of Michigan , Ann Arbor, Michigan
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37
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Zhang M, Wang D, Kang Y, Wu JX, Yao F, Pan C, Yan Z, Song C, Chen L. Structure of the mechanosensitive OSCA channels. Nat Struct Mol Biol 2018; 25:850-858. [DOI: 10.1038/s41594-018-0117-6] [Citation(s) in RCA: 87] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 07/24/2018] [Indexed: 02/05/2023]
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38
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Gating mechanism of the extracellular entry to the lipid pathway in a TMEM16 scramblase. Nat Commun 2018; 9:3251. [PMID: 30108217 PMCID: PMC6092359 DOI: 10.1038/s41467-018-05724-1] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Accepted: 07/04/2018] [Indexed: 12/22/2022] Open
Abstract
Members of the TMEM16/ANO family of membrane proteins are Ca2+-activated phospholipid scramblases and/or Cl− channels. A membrane-exposed hydrophilic groove in these proteins serves as a shared translocation pathway for ions and lipids. However, the mechanism by which lipids gain access to and permeate through the groove remains poorly understood. Here, we combine quantitative scrambling assays and molecular dynamic simulations to identify the key steps regulating lipid movement through the groove. Lipid scrambling is limited by two constrictions defined by evolutionarily conserved charged and polar residues, one extracellular and the other near the membrane mid-point. The region between these constrictions is inaccessible to lipids and water molecules, suggesting that the groove is in a non-conductive conformation. A sequence of lipid-triggered reorganizations of interactions between these residues and the permeating lipids propagates from the extracellular entryway to the central constriction, allowing the groove to open and coordinate the headgroups of transiting lipids. Some TMEM16 family members are Ca2+-dependent phospholipid scramblases, which also mediate non-selective ion transport; however, the mechanism how lipids permeate through the TMEM16 remains poorly understood. Here, the authors combine biochemical assays and simulations to identify the key steps regulating lipid movement through the membrane-exposed groove.
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39
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Bill A, Alex Gaither L. The Mechanistic Role of the Calcium-Activated Chloride Channel ANO1 in Tumor Growth and Signaling. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 966:1-14. [PMID: 28293832 DOI: 10.1007/5584_2016_201] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Multiple studies have described the high expression and amplification of Anoctamin 1 (ANO1) in various cancers, including, but not limited to breast cancer, head and neck cancer, gastrointestinal stromal tumors and glioblastoma. ANO1 has been demonstrated to be critical for tumor growth in breast and head and neck cancers through its regulation of EGFR signaling and pathway modulators like MAPK and protein kinase B. However, the discovery of ANO1 as a calcium activated chloride channel came as a surprise to the field and has given rise to many questions. How does a chloride channel promote oncogenesis? Is the chloride channel function of ANO1 important for its role in cancer? Does ANO1 exhibits chloride-independent functions in cancer cells? This review summarizes the current understanding of ANO1's function in cancer, provides a synopsis of the findings addressing the open questions in the field and gives an outlook on the promising future of ANO1 as a potential therapeutic target for the treatment of various cancers.
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Affiliation(s)
- Anke Bill
- Novartis Institutes for Biomedical Research, Cambridge, MA, 02139, USA
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40
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Falzone ME, Malvezzi M, Lee BC, Accardi A. Known structures and unknown mechanisms of TMEM16 scramblases and channels. J Gen Physiol 2018; 150:933-947. [PMID: 29915161 PMCID: PMC6028493 DOI: 10.1085/jgp.201711957] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Accepted: 05/29/2018] [Indexed: 12/25/2022] Open
Abstract
Falzone et al. interpret the mechanisms underlying the activity of TMEM16 family members from recent structural and functional work. The TMEM16 family of membrane proteins is composed of both Ca2+-gated Cl− channels and Ca2+-dependent phospholipid scramblases. The functional diversity of TMEM16s underlies their involvement in numerous signal transduction pathways that connect changes in cytosolic Ca2+ levels to cellular signaling networks. Indeed, defects in the function of several TMEM16s cause a variety of genetic disorders, highlighting their fundamental pathophysiological importance. Here, we review how our mechanistic understanding of TMEM16 function has been shaped by recent functional and structural work. Remarkably, the recent determination of near-atomic-resolution structures of TMEM16 proteins of both functional persuasions has revealed how relatively minimal rearrangements in the substrate translocation pathway are sufficient to precipitate the dramatic functional differences that characterize the family. These structures, when interpreted in the light of extensive functional analysis, point to an unusual mechanism for Ca2+-dependent activation of TMEM16 proteins in which substrate permeation is regulated by a combination of conformational rearrangements and electrostatics. These breakthroughs pave the way to elucidate the mechanistic bases of ion and lipid transport by the TMEM16 proteins and unravel the molecular links between these transport activities and their function in human pathophysiology.
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Affiliation(s)
- Maria E Falzone
- Department of Biochemistry, Weill Cornell Medical School, New York, NY
| | - Mattia Malvezzi
- Department of Anesthesiology, Weill Cornell Medical School, New York, NY
| | - Byoung-Cheol Lee
- Department of Anesthesiology, Weill Cornell Medical School, New York, NY
| | - Alessio Accardi
- Department of Biochemistry, Weill Cornell Medical School, New York, NY .,Department of Anesthesiology, Weill Cornell Medical School, New York, NY.,Department of Physiology, Biophysics and Systems Biology, Weill Cornell Medical School, New York, NY
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41
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Rottgen TS, Nickerson AJ, Rajendran VM. Calcium-Activated Cl - Channel: Insights on the Molecular Identity in Epithelial Tissues. Int J Mol Sci 2018; 19:E1432. [PMID: 29748496 PMCID: PMC5983713 DOI: 10.3390/ijms19051432] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 05/07/2018] [Accepted: 05/08/2018] [Indexed: 12/25/2022] Open
Abstract
Calcium-activated chloride secretion in epithelial tissues has been described for many years. However, the molecular identity of the channel responsible for the Ca2+-activated Cl− secretion in epithelial tissues has remained a mystery. More recently, TMEM16A has been identified as a new putative Ca2+-activated Cl− channel (CaCC). The primary goal of this article will be to review the characterization of TMEM16A, as it relates to the physical structure of the channel, as well as important residues that confer voltage and Ca2+-sensitivity of the channel. This review will also discuss the role of TMEM16A in epithelial physiology and potential associated-pathophysiology. This will include discussion of developed knockout models that have provided much needed insight on the functional localization of TMEM16A in several epithelial tissues. Finally, this review will examine the implications of the identification of TMEM16A as it pertains to potential novel therapies in several pathologies.
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Affiliation(s)
- Trey S Rottgen
- Department of Physiology, Pharmacology, and Neuroscience, West Virginia University School of Medicine, Morgantown, WV 26506, USA.
- Department of Biochemistry and Molecular Pharmacology, West Virginia University School of Medicine, Morgantown, WV 26506, USA.
| | - Andrew J Nickerson
- Department of Physiology, Pharmacology, and Neuroscience, West Virginia University School of Medicine, Morgantown, WV 26506, USA.
- Department of Biochemistry and Molecular Pharmacology, West Virginia University School of Medicine, Morgantown, WV 26506, USA.
| | - Vazhaikkurichi M Rajendran
- Department of Physiology, Pharmacology, and Neuroscience, West Virginia University School of Medicine, Morgantown, WV 26506, USA.
- Department of Biochemistry and Molecular Pharmacology, West Virginia University School of Medicine, Morgantown, WV 26506, USA.
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42
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Peters CJ, Gilchrist JM, Tien J, Bethel NP, Qi L, Chen T, Wang L, Jan YN, Grabe M, Jan LY. The Sixth Transmembrane Segment Is a Major Gating Component of the TMEM16A Calcium-Activated Chloride Channel. Neuron 2018; 97:1063-1077.e4. [PMID: 29478917 DOI: 10.1016/j.neuron.2018.01.048] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2017] [Revised: 12/03/2017] [Accepted: 01/26/2018] [Indexed: 11/29/2022]
Abstract
Calcium-activated chloride channels (CaCCs) formed by TMEM16A or TMEM16B are broadly expressed in the nervous system, smooth muscles, exocrine glands, and other tissues. With two calcium-binding sites and a pore within each monomer, the dimeric CaCC exhibits voltage-dependent calcium sensitivity. Channel activity also depends on the identity of permeant anions. To understand how CaCC regulates neuronal signaling and how CaCC is, in turn, modulated by neuronal activity, we examined the molecular basis of CaCC gating. Here, we report that voltage modulation of TMEM16A-CaCC involves voltage-dependent occupancy of calcium- and anion-binding site(s) within the membrane electric field as well as a voltage-dependent conformational change intrinsic to the channel protein. These gating modalities all critically depend on the sixth transmembrane segment.
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Affiliation(s)
- Christian J Peters
- Departments of Physiology, Biophysics and Biochemistry, University of California, San Francisco, San Francisco, CA 94158, USA.
| | - John M Gilchrist
- Departments of Physiology, Biophysics and Biochemistry, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Jason Tien
- Departments of Physiology, Biophysics and Biochemistry, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Neville P Bethel
- Department of Pharmaceutical Chemistry and Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Lijun Qi
- Departments of Physiology, Biophysics and Biochemistry, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Tingxu Chen
- Departments of Physiology, Biophysics and Biochemistry, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Lynn Wang
- Departments of Physiology, Biophysics and Biochemistry, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Yuh Nung Jan
- Departments of Physiology, Biophysics and Biochemistry, University of California, San Francisco, San Francisco, CA 94158, USA; Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Michael Grabe
- Department of Pharmaceutical Chemistry and Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Lily Y Jan
- Departments of Physiology, Biophysics and Biochemistry, University of California, San Francisco, San Francisco, CA 94158, USA; Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158, USA.
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43
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Affiliation(s)
- H Criss Hartzell
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322
| | - Jarred M Whitlock
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322
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44
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Cryo-EM structures of the TMEM16A calcium-activated chloride channel. Nature 2017; 552:426-429. [PMID: 29236684 PMCID: PMC5750132 DOI: 10.1038/nature25024] [Citation(s) in RCA: 224] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2017] [Accepted: 11/10/2017] [Indexed: 12/19/2022]
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45
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Wang L, Wang K. Highlights for the 6th International Ion Channel Conference: ion channel structure, function, disease and therapeutics. Acta Pharm Sin B 2017; 7:665-669. [PMID: 29159026 PMCID: PMC5687311 DOI: 10.1016/j.apsb.2017.09.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 08/15/2017] [Indexed: 11/17/2022] Open
Abstract
To foster communication and interactions amongst international scholars and scientists in the field of ion channel research, the 6th International Ion Channel Conference (IICC-2017) was held between June 23–27, 2017 in the eastern coastal city of Qingdao, China. The meeting consisted of 450 attendees and 130 speakers and poster presenters. The program consisted of research progress, new findings and ongoing studies that were focused on (1) Ion channel structure and function; (2) Ion channel physiology and human diseases; (3) Ion channels as targets for drug discovery; (4) Technological advances in ion channel research. An insightful overview was presented on the structure and function of the mechanotransduction channel Drosophila NOMPC (No mechanoreceptor potential C), a member of the transient receptor potential (TRP) channel family. Recent studies on Transmembrane protein 16 or Anoctamin-1 (TMEM16A, a member of the calcium-activated chloride channel [CaCC] family) were summarized as well. In addition, topics for ion channel regulation, homeostatic feedback and brain disorders were thoroughly discussed. The presentations at the IICC-2017 offer new insights into our understanding of ion channel structures and functions, and ion channels as targets for drug discovery.
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46
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Truong EC, Phuan PW, Reggi AL, Ferrera L, Galietta LJ, Levy SE, Moises AC, Cil O, Diez-Cecilia E, Lee S, Verkman AS, Anderson MO. Substituted 2-Acylaminocycloalkylthiophene-3-carboxylic Acid Arylamides as Inhibitors of the Calcium-Activated Chloride Channel Transmembrane Protein 16A (TMEM16A). J Med Chem 2017; 60:4626-4635. [PMID: 28493701 PMCID: PMC5516794 DOI: 10.1021/acs.jmedchem.7b00020] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Transmembrane protein 16A (TMEM16A), also called anoctamin 1 (ANO1), is a calcium-activated chloride channel expressed widely mammalian cells, including epithelia, vascular smooth muscle tissue, electrically excitable cells, and some tumors. TMEM16A inhibitors have been proposed for treatment of disorders of epithelial fluid and mucus secretion, hypertension, asthma, and possibly cancer. Herein we report, by screening, the discovery of 2-acylaminocycloalkylthiophene-3-carboxylic acid arylamides (AACTs) as inhibitors of TMEM16A and analysis of 48 synthesized analogs (10ab-10bw) of the original AACT compound (10aa). Structure-activity studies indicated the importance of benzene substituted as 2- or 4-methyl, or 4-fluoro, and defined the significance of thiophene substituents and size of the cycloalkylthiophene core. The most potent compound (10bm), which contains an unusual bromodifluoroacetamide at the thiophene 2-position, had IC50 of ∼30 nM, ∼3.6-fold more potent than the most potent previously reported TMEM16A inhibitor 4 (Ani9), and >10-fold improved metabolic stability. Direct and reversible inhibition of TMEM16A by 10bm was demonstrated by patch-clamp analysis. AACTs may be useful as pharmacological tools to study TMEM16A function and as potential drug development candidates.
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Affiliation(s)
- Eric C. Truong
- Department of Chemistry and Biochemistry, San Francisco State University, San Francisco CA, 94132-4136 USA
| | - Puay W. Phuan
- Departments of Medicine and Physiology, University of California, San Francisco CA, 94143-0521 USA
| | - Amanda L. Reggi
- Department of Chemistry and Biochemistry, San Francisco State University, San Francisco CA, 94132-4136 USA
| | - Loretta Ferrera
- U.O.C. Genetica Medica, Istituto Giannina Gaslini, Genova, ITALY
| | - Luis J.V. Galietta
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli (NA), ITALY
| | - Sarah E. Levy
- Department of Chemistry and Biochemistry, San Francisco State University, San Francisco CA, 94132-4136 USA
| | - Alannah C. Moises
- Department of Chemistry and Biochemistry, San Francisco State University, San Francisco CA, 94132-4136 USA
| | - Onur Cil
- Departments of Medicine and Physiology, University of California, San Francisco CA, 94143-0521 USA
| | - Elena Diez-Cecilia
- Department of Chemistry and Biochemistry, San Francisco State University, San Francisco CA, 94132-4136 USA
| | - Sujin Lee
- Departments of Medicine and Physiology, University of California, San Francisco CA, 94143-0521 USA
| | - Alan S. Verkman
- Departments of Medicine and Physiology, University of California, San Francisco CA, 94143-0521 USA
| | - Marc O. Anderson
- Department of Chemistry and Biochemistry, San Francisco State University, San Francisco CA, 94132-4136 USA
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47
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Paulino C, Neldner Y, Lam AKM, Kalienkova V, Brunner JD, Schenck S, Dutzler R. Structural basis for anion conduction in the calcium-activated chloride channel TMEM16A. eLife 2017; 6:e26232. [PMID: 28561733 PMCID: PMC5470873 DOI: 10.7554/elife.26232] [Citation(s) in RCA: 106] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 04/11/2017] [Indexed: 12/11/2022] Open
Abstract
The calcium-activated chloride channel TMEM16A is a member of a conserved protein family that comprises ion channels and lipid scramblases. Although the structure of the scramblase nhTMEM16 has defined the architecture of the family, it was unknown how a channel has adapted to cope with its distinct functional properties. Here we have addressed this question by the structure determination of mouse TMEM16A by cryo-electron microscopy and a complementary functional characterization. The protein shows a similar organization to nhTMEM16, except for changes at the site of catalysis. There, the conformation of transmembrane helices constituting a membrane-spanning furrow that provides a path for lipids in scramblases has changed to form an enclosed aqueous pore that is largely shielded from the membrane. Our study thus reveals the structural basis of anion conduction in a TMEM16 channel and it defines the foundation for the diverse functional behavior in the TMEM16 family.
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Affiliation(s)
- Cristina Paulino
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Yvonne Neldner
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Andy KM Lam
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | | | | | - Stephan Schenck
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Raimund Dutzler
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
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48
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Abstract
The TMEM16 protein family has 10 members, each of which carries 10 transmembrane segments. TMEM16A and 16B are Ca2+-activated Cl- channels. Several other members, including TMEM16F, promote phospholipid scrambling between the inner and outer leaflets of a cell membrane in response to intracellular Ca2+ However, the mechanism by which TMEM16 proteins translocate phospholipids in plasma membranes remains elusive. Here we show that Ca2+-activated, TMEM16F-supported phospholipid scrambling proceeds at 4 °C. Similar to TMEM16F and 16E, seven TMEM16 family members were found to carry a domain (SCRD; scrambling domain) spanning the fourth and fifth transmembrane segments that conferred scrambling ability to TMEM16A. By introducing point mutations into TMEM16F, we found that a lysine in the fourth transmembrane segment of the SCRD as well as an arginine in the third and a glutamic acid in the sixth transmembrane segment were important for exposing phosphatidylserine from the inner to the outer leaflet. However, their role in internalizing phospholipids was limited. Our results suggest that TMEM16 provides a cleft containing hydrophilic "stepping stones" for the outward translocation of phospholipids.
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49
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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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50
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Fuest M, Rangharajan KK, Boone C, Conlisk AT, Prakash S. Cation Dependent Surface Charge Regulation in Gated Nanofluidic Devices. Anal Chem 2017; 89:1593-1601. [PMID: 28208271 DOI: 10.1021/acs.analchem.6b03653] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Surface charge governs nanoscale aqueous electrolyte transport, both in engineered analytical systems and in biological entities such as ion channels and ion pumps as a function of ion type and concentration. Embedded electrodes in a nanofluidic channel, isolated from the fluid in the channel by a dielectric layer, act as active, tunable gates to systematically modify local surface charge density at the interface between the nanochannel surface and the aqueous electrolyte solution, causing significant changes in measured nanochannel conductance. A systematic comparison of transport of monovalent electrolytes [potassium chloride (KCl), sodium chloride (NaCl)], 2:1 electrolytes [magnesium chloride (MgCl2), calcium chloride (CaCl2)], and electrolyte mixtures (KCl + CaCl2) through a gated nanofluidic device was performed. Ion-surface interactions between divalent Ca2+ and Mg2+ ions and the nanochannel walls reduced the native surface charge density by up to ∼4-5 times compared to the monovalent cations. In electrolyte mixtures, Ca2+ was the dominating cation with nanochannel conductance independent of KCl concentration. Systematic changes in local electrostatic surface state induced by the gate electrode are impacted by the divalent cation-surface interactions, limiting modulation of the local surface potential by the gate electrode and resulting in cation dependent nanoscale ion transport as seen through conductance measurements and numerical models.
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Affiliation(s)
- Marie Fuest
- Department of Mechanical and Aerospace Engineering, The Ohio State University , Columbus, Ohio 43210, United States
| | - Kaushik K Rangharajan
- Department of Mechanical and Aerospace Engineering, The Ohio State University , Columbus, Ohio 43210, United States
| | - Caitlin Boone
- Department of Mechanical and Aerospace Engineering, The Ohio State University , Columbus, Ohio 43210, United States
| | - A T Conlisk
- Department of Mechanical and Aerospace Engineering, The Ohio State University , Columbus, Ohio 43210, United States
| | - Shaurya Prakash
- Department of Mechanical and Aerospace Engineering, The Ohio State University , Columbus, Ohio 43210, United States
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