1
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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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2
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Kolesnikov DO, Grigorieva ER, Nomerovskaya MA, Reshetin DS, Shalygin AV, Kaznacheyeva E. The Effect of Calcium Ions on the Electrophysiological Properties of Single ANO6 Channels. Acta Naturae 2024; 16:40-47. [PMID: 38698960 PMCID: PMC11062105 DOI: 10.32607/actanaturae.27338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2023] [Accepted: 12/23/2024] [Indexed: 05/05/2024] Open
Abstract
Proteins belonging to the anoctamin (ANO) family form calcium-activated chloride channels (CaCCs). The most unusual member of this family, ANO6 (TMEM16F), simultaneously exhibits the functions of calcium-dependent scramblase and the ion channel. ANO6 affects the plasma membrane dynamics and phosphatidylserine transport; it is also involved in programmed cell death. The properties of ANO6 channels remain the subject of debate. In this study, we investigated the effect of variations in the intracellular and extracellular concentrations of calcium ions on the electrophysiological properties of endogenous ANO6 channels by recording single ANO6 channels. It has been demonstrated that (1) a high calcium concentration in an extracellular solution increases the activity of endogenous ANO6 channels, (2) the permeability of endogenous ANO6 channels for chloride ions is independent of the extracellular concentration of calcium ions, (3) that an increase in the intracellular calcium concentration leads to the activation of endogenous ANO6 channels with double amplitude, and (4) that the kinetics of the channel depend on the plasma membrane potential rather than the intracellular concentration of calcium ions. Our findings give grounds for proposing new mechanisms for the regulation of the ANO6 channel activity by calcium ions both at the inner and outer sides of the membrane.
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Affiliation(s)
- D. O. Kolesnikov
- Institute of Cytology of the Russian Academy of Sciences, St. Petersburg, 194064 Russian Federation
| | - E. R. Grigorieva
- Institute of Cytology of the Russian Academy of Sciences, St. Petersburg, 194064 Russian Federation
| | - M. A. Nomerovskaya
- Institute of Cytology of the Russian Academy of Sciences, St. Petersburg, 194064 Russian Federation
| | - D. S. Reshetin
- Institute of Cytology of the Russian Academy of Sciences, St. Petersburg, 194064 Russian Federation
| | - A. V. Shalygin
- Institute of Cytology of the Russian Academy of Sciences, St. Petersburg, 194064 Russian Federation
| | - E.V. Kaznacheyeva
- Institute of Cytology of the Russian Academy of Sciences, St. Petersburg, 194064 Russian Federation
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3
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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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4
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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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5
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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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6
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Arndt M, Alvadia C, Straub MS, Clerico Mosina V, Paulino C, Dutzler R. Structural basis for the activation of the lipid scramblase TMEM16F. Nat Commun 2022; 13:6692. [PMID: 36335104 PMCID: PMC9637102 DOI: 10.1038/s41467-022-34497-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2022] [Accepted: 10/26/2022] [Indexed: 11/06/2022] Open
Abstract
TMEM16F, a member of the conserved TMEM16 family, plays a central role in the initiation of blood coagulation and the fusion of trophoblasts. The protein mediates passive ion and lipid transport in response to an increase in intracellular Ca2+. However, the mechanism of how the protein facilitates both processes has remained elusive. Here we investigate the basis for TMEM16F activation. In a screen of residues lining the proposed site of conduction, we identify mutants with strongly activating phenotype. Structures of these mutants determined herein by cryo-electron microscopy show major rearrangements leading to the exposure of hydrophilic patches to the membrane, whose distortion facilitates lipid diffusion. The concomitant opening of a pore promotes ion conduction in the same protein conformation. Our work has revealed a mechanism that is distinct for this branch of the family and that will aid the development of a specific pharmacology for a promising drug target.
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Affiliation(s)
- Melanie Arndt
- grid.7400.30000 0004 1937 0650Department of Biochemistry University of Zurich, Winterthurer Str. 190, CH-8057 Zurich, Switzerland
| | - Carolina Alvadia
- grid.7400.30000 0004 1937 0650Department of Biochemistry University of Zurich, Winterthurer Str. 190, CH-8057 Zurich, Switzerland
| | - Monique S. Straub
- grid.7400.30000 0004 1937 0650Department of Biochemistry University of Zurich, Winterthurer Str. 190, CH-8057 Zurich, Switzerland
| | - Vanessa Clerico Mosina
- grid.4830.f0000 0004 0407 1981Department of Structural Biology and Membrane Enzymology at the Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands
| | - Cristina Paulino
- grid.4830.f0000 0004 0407 1981Department of Structural Biology and Membrane Enzymology at the Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands
| | - Raimund Dutzler
- grid.7400.30000 0004 1937 0650Department of Biochemistry University of Zurich, Winterthurer Str. 190, CH-8057 Zurich, Switzerland
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7
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Jia Z, Huang J, Chen J. Activation of TMEM16F by inner gate charged mutations and possible lipid/ion permeation mechanisms. Biophys J 2022; 121:3445-3457. [PMID: 35978550 PMCID: PMC9515230 DOI: 10.1016/j.bpj.2022.08.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 05/24/2022] [Accepted: 08/12/2022] [Indexed: 11/19/2022] Open
Abstract
Transmembrane protein 16F (TMEM16F) is a ubiquitously expressed Ca2+-activated phospholipid scramblase that also functions as a largely non-selective ion channel. Though recent structural studies have revealed the closed and intermediate conformations of mammalian TMEM16F (mTMEM16F), the open and conductive state remains elusive. Instead, it has been proposed that an open hydrophilic pathway may not be required for lipid scrambling. We previously identified an inner activation gate, consisting of F518, Y563, and I612, and showed that charged mutations of the inner gate residues led to constitutively active mTMEM16F scrambling. Herein, atomistic simulations show that lysine substitution of F518 and Y563 can indeed lead to spontaneous opening of the permeation pore in the Ca2+-bound state of mTMEM16F. Dilation of the pore exposes hydrophilic patches in the upper pore region, greatly increases the pore hydration level, and enables lipid scrambling. The putative open state of mTMEM16F resembles the active state of fungal scramblases and is a meta-stable state for the wild-type protein in the Ca2+-bound state. Therefore, mTMEM16F may be capable of supporting the canonical in-groove scrambling mechanism in addition to the out-of-groove one. Further analysis reveals that the in-groove phospholipid and ion transduction pathways of mTMEM16F overlap from the intracellular side up to the inner gate but diverge from each other with different exits to the extracellular side of membrane.
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Affiliation(s)
- Zhiguang Jia
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts
| | - Jian Huang
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts
| | - Jianhan Chen
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts; Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Massachusetts.
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8
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Zhang Y, Liang P, Yang L, Shan KZ, Feng L, Chen Y, Liedtke W, Coyne CB, Yang H. Functional coupling between TRPV4 channel and TMEM16F modulates human trophoblast fusion. eLife 2022; 11:e78840. [PMID: 35670667 PMCID: PMC9236608 DOI: 10.7554/elife.78840] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 06/05/2022] [Indexed: 11/15/2022] Open
Abstract
TMEM16F, a Ca2+-activated phospholipid scramblase (CaPLSase), is critical for placental trophoblast syncytialization, HIV infection, and SARS-CoV2-mediated syncytialization, however, how TMEM16F is activated during cell fusion is unclear. Here, using trophoblasts as a model for cell fusion, we demonstrate that Ca2+ influx through the Ca2+ permeable transient receptor potential vanilloid channel TRPV4 is critical for TMEM16F activation and plays a role in subsequent human trophoblast fusion. GSK1016790A, a TRPV4 specific agonist, robustly activates TMEM16F in trophoblasts. We also show that TRPV4 and TMEM16F are functionally coupled within Ca2+ microdomains in a human trophoblast cell line using patch-clamp electrophysiology. Pharmacological inhibition or gene silencing of TRPV4 hinders TMEM16F activation and subsequent trophoblast syncytialization. Our study uncovers the functional expression of TRPV4 and one of the physiological activation mechanisms of TMEM16F in human trophoblasts, thus providing us with novel strategies to regulate CaPLSase activity as a critical checkpoint of physiologically and disease-relevant cell fusion events.
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Affiliation(s)
- Yang Zhang
- Department of Biochemistry, Duke University Medical CenterDurhamUnited States
| | - Pengfei Liang
- Department of Biochemistry, Duke University Medical CenterDurhamUnited States
| | - Liheng Yang
- Department of Molecular Genetics and Microbiology, Duke University Medical CenterDurhamUnited States
| | - Ke Zoe Shan
- Department of Biochemistry, Duke University Medical CenterDurhamUnited States
| | - Liping Feng
- Department of Obstetrics and Gynecology, Duke University Medical CentreDurhamUnited States
- MOE-Shanghai Key Laboratory of Children's Environmental Health, Xinhua HospitalShanghaiChina
| | - Yong Chen
- Department of Neurology, Duke University Medical CenterDurhamUnited States
| | - Wolfgang Liedtke
- Department of Neurology, Duke University Medical CenterDurhamUnited States
- Department of Anesthesiology, Duke University Medical CenterDurhamUnited States
- Department of Neurobiology, Duke University Medical CenterDurhamUnited States
- College of Dentistry, Department of Molecular Pathobiology, NYUNew YorkUnited States
| | - Carolyn B Coyne
- Department of Molecular Genetics and Microbiology, Duke University Medical CenterDurhamUnited States
- Duke Human Vaccine Institute, Duke UniversityDurhamUnited States
| | - Huanghe Yang
- Department of Biochemistry, Duke University Medical CenterDurhamUnited States
- Department of Neurobiology, Duke University Medical CenterDurhamUnited States
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9
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Cheng Y, Feng S, Puchades C, Ko J, Figueroa E, Chen Y, Wu H, Gu S, Han T, Li J, Ho B, Shoichet B, Jan YN, Jan L. Identification of a conserved drug binding pocket in TMEM16 proteins. RESEARCH SQUARE 2022:rs.3.rs-1296933. [PMID: 35169791 PMCID: PMC8845511 DOI: 10.21203/rs.3.rs-1296933/v1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
The TMEM16 family of calcium-activated membrane proteins includes ten mammalian paralogs (TMEM16A-K) playing distinct physiological roles with some implicated in cancer and airway diseases. Their modulators with therapeutic potential include 1PBC, a potent inhibitor with anti-tumoral properties, and the FDA-approved drug niclosamide that targets TMEM16F to inhibit syncytia formation induced by SARS-CoV-2 infection. Here, we report cryo-EM structures of TMEM16F associated with 1PBC and niclosamide, revealing that both molecules bind the same drug binding pocket. We functionally and computationally validate this binding pocket in TMEM16A as well as TMEM16F, thereby showing that drug modulation also involves residues that are not conserved between TMEM16A and TMEM16F. This study establishes a much-needed structural framework for the development of more potent and more specific drug molecules targeting TMEM16 proteins.
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Affiliation(s)
| | | | | | | | | | | | - Hao Wu
- University of California San Francisco
| | | | | | | | | | | | | | - Lily Jan
- University of California, San Francisco
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10
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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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11
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Le SC, Liang P, Lowry AJ, Yang H. Gating and Regulatory Mechanisms of TMEM16 Ion Channels and Scramblases. Front Physiol 2021; 12:787773. [PMID: 34867487 PMCID: PMC8640346 DOI: 10.3389/fphys.2021.787773] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 10/29/2021] [Indexed: 12/30/2022] Open
Abstract
The transmembrane protein 16 (TMEM16) family consists of Ca2+-activated ion channels and Ca2+-activated phospholipid scramblases (CaPLSases) that passively flip-flop phospholipids between the two leaflets of the membrane bilayer. Owing to their diverse functions, TMEM16 proteins have been implicated in various human diseases, including asthma, cancer, bleeding disorders, muscular dystrophy, arthritis, epilepsy, dystonia, ataxia, and viral infection. To understand TMEM16 proteins in health and disease, it is critical to decipher their molecular mechanisms of activation gating and regulation. Structural, biophysical, and computational characterizations over the past decade have greatly advanced the molecular understanding of TMEM16 proteins. In this review, we summarize major structural features of the TMEM16 proteins with a focus on regulatory mechanisms and gating.
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Affiliation(s)
- Son C. Le
- Department of Biochemistry, Duke University Medical Center, Durham, NC, United States
| | - Pengfei Liang
- Department of Biochemistry, Duke University Medical Center, Durham, NC, United States
| | - Augustus J. Lowry
- Department of Biochemistry, Duke University Medical Center, Durham, NC, United States
| | - Huanghe Yang
- Department of Biochemistry, Duke University Medical Center, Durham, NC, United States
- Department of Neurobiology, Duke University Medical Center, Durham, NC, United States
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12
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Deisl C, Hilgemann DW, Syeda R, Fine M. TMEM16F and dynamins control expansive plasma membrane reservoirs. Nat Commun 2021; 12:4990. [PMID: 34404808 PMCID: PMC8371123 DOI: 10.1038/s41467-021-25286-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 07/29/2021] [Indexed: 11/09/2022] Open
Abstract
Cells can expand their plasma membrane laterally by unfolding membrane undulations and by exocytosis. Here, we describe a third mechanism involving invaginations held shut by the membrane adapter, dynamin. Compartments open when Ca activates the lipid scramblase, TMEM16F, anionic phospholipids escape from the cytoplasmic monolayer in exchange for neutral lipids, and dynamins relax. Deletion of TMEM16F or dynamins blocks expansion, with loss of dynamin expression generating a maximally expanded basal plasma membrane state. Re-expression of dynamin2 or its GTPase-inactivated mutant, but not a lipid binding mutant, regenerates reserve compartments and rescues expansion. Dynamin2-GFP fusion proteins form punctae that rapidly dissipate from these compartments during TMEM16F activation. Newly exposed compartments extend deeply into the cytoplasm, lack numerous organellar markers, and remain closure-competent for many seconds. Without Ca, compartments open slowly when dynamins are sequestered by cytoplasmic dynamin antibodies or when scrambling is mimicked by neutralizing anionic phospholipids and supplementing neutral lipids. Activation of Ca-permeable mechanosensitive channels via cell swelling or channel agonists opens the compartments in parallel with phospholipid scrambling. Thus, dynamins and TMEM16F control large plasma membrane reserves that open in response to lateral membrane stress and Ca influx.
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Affiliation(s)
- Christine Deisl
- University of Texas Southwestern Medical Center, Department of Physiology, Dallas, TX, USA
| | - Donald W Hilgemann
- University of Texas Southwestern Medical Center, Department of Physiology, Dallas, TX, USA.
| | - Ruhma Syeda
- University of Texas Southwestern Medical Center, Department of Neuroscience, Dallas, TX, USA
| | - Michael Fine
- University of Texas Southwestern Medical Center, Department of Physiology, Dallas, TX, USA.
- University of Texas Southwestern Medical Center, Department of Molecular Genetics, Dallas, TX, USA.
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13
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Anion and Cation Permeability of the Mouse TMEM16F Calcium-Activated Channel. Int J Mol Sci 2021; 22:ijms22168578. [PMID: 34445284 PMCID: PMC8395294 DOI: 10.3390/ijms22168578] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 07/31/2021] [Accepted: 08/04/2021] [Indexed: 12/27/2022] Open
Abstract
TMEM16F is involved in several physiological processes, such as blood coagulation, bone development and virus infections. This protein acts both as a Ca2+-dependent phospholipid scramblase and a Ca2+-activated ion channel but several studies have reported conflicting results about the ion selectivity of the TMEM16F-mediated current. Here, we have performed a detailed side-by-side comparison of the ion selectivity of TMEM16F using the whole-cell and inside-out excised patch configurations to directly compare the results. In inside-out configuration, Ca2+-dependent activation was fast and the TMEM16F-mediated current was activated in a few milliseconds, while in whole-cell recordings full activation required several minutes. We determined the relative permeability between Na+ and Cl¯ (PNa/PCl) using the dilution method in both configurations. The TMEM16F-mediated current was highly nonselective, but there were differences depending on the configuration of the recordings. In whole-cell recordings, PNa/PCl was approximately 0.5, indicating a slight preference for Cl¯ permeation. In contrast, in inside-out experiments the TMEM16F channel showed a higher permeability for Na+ with PNa/PCl reaching 3.7. Our results demonstrate that the time dependence of Ca2+ activation and the ion selectivity of TMEM16F depend on the recording configuration.
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14
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P2X7 Receptors and TMEM16 Channels Are Functionally Coupled with Implications for Macropore Formation and Current Facilitation. Int J Mol Sci 2021; 22:ijms22126542. [PMID: 34207150 PMCID: PMC8234106 DOI: 10.3390/ijms22126542] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 06/04/2021] [Accepted: 06/07/2021] [Indexed: 02/03/2023] Open
Abstract
P2X7 receptors (P2X7) are cationic channels involved in many diseases. Following their activation by extracellular ATP, distinct signaling pathways are triggered, which lead to various physiological responses such as the secretion of pro-inflammatory cytokines or the modulation of cell death. P2X7 also exhibit unique behaviors, such as “macropore” formation, which corresponds to enhanced large molecule cell membrane permeability and current facilitation, which is caused by prolonged activation. These two phenomena have often been confounded but, thus far, no clear mechanisms have been resolved. Here, by combining different approaches including whole-cell and single-channel recordings, pharmacological and biochemical assays, CRISPR/Cas9 technology and cell imaging, we provide evidence that current facilitation and macropore formation involve functional complexes comprised of P2X7 and TMEM16, a family of Ca2+-activated ion channel/scramblases. We found that current facilitation results in an increase of functional complex-embedded P2X7 open probability, a result that is recapitulated by plasma membrane cholesterol depletion. We further show that macropore formation entails two distinct large molecule permeation components, one of which requires functional complexes featuring TMEM16F subtype, the other likely being direct permeation through the P2X7 pore itself. Such functional complexes can be considered to represent a regulatory hub that may orchestrate distinct P2X7 functionalities.
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15
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Kostritskii AY, Machtens JP. Molecular mechanisms of ion conduction and ion selectivity in TMEM16 lipid scramblases. Nat Commun 2021; 12:2826. [PMID: 33990555 PMCID: PMC8121942 DOI: 10.1038/s41467-021-22724-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Accepted: 03/23/2021] [Indexed: 02/03/2023] Open
Abstract
TMEM16 lipid scramblases transport lipids and also operate as ion channels with highly variable ion selectivities and various physiological functions. However, their molecular mechanisms of ion conduction and selectivity remain largely unknown. Using computational electrophysiology simulations at atomistic resolution, we identified the main ion-conductive state of TMEM16 lipid scramblases, in which an ion permeation pathway is lined by lipid headgroups that directly interact with permeating ions in a voltage polarity-dependent manner. We found that lipid headgroups modulate the ion-permeability state and regulate ion selectivity to varying degrees in different scramblase isoforms, depending on the amino-acid composition of the pores. Our work has defined the structural basis of ion conduction and selectivity in TMEM16 lipid scramblases and uncovered the mechanisms responsible for the direct effects of membrane lipids on the conduction properties of ion channels.
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Affiliation(s)
- Andrei Y. Kostritskii
- grid.8385.60000 0001 2297 375XInstitute of Biological Information Processing (IBI-1), Molekular- und Zellphysiologie, and JARA-HPC, Forschungszentrum Jülich, Jülich, Germany ,grid.1957.a0000 0001 0728 696XInstitute of Clinical Pharmacology, RWTH Aachen University, Aachen, Germany ,grid.1957.a0000 0001 0728 696XDepartment of Physics, RWTH Aachen University, Aachen, Germany
| | - Jan-Philipp Machtens
- grid.8385.60000 0001 2297 375XInstitute of Biological Information Processing (IBI-1), Molekular- und Zellphysiologie, and JARA-HPC, Forschungszentrum Jülich, Jülich, Germany ,grid.1957.a0000 0001 0728 696XInstitute of Clinical Pharmacology, RWTH Aachen University, Aachen, Germany
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16
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Kolesnikov D, Perevoznikova A, Gusev K, Glushankova L, Kaznacheyeva E, Shalygin A. Electrophysiological Properties of Endogenous Single Ca 2+ Activated Cl - Channels Induced by Local Ca 2+ Entry in HEK293. Int J Mol Sci 2021; 22:4767. [PMID: 33946319 PMCID: PMC8124839 DOI: 10.3390/ijms22094767] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 04/26/2021] [Accepted: 04/28/2021] [Indexed: 12/19/2022] Open
Abstract
Microdomains formed by proteins of endoplasmic reticulum and plasma membrane play a key role in store-operated Ca2+ entry (SOCE). Ca2+ release through inositol 1,4,5-trisphosphate receptor (IP3R) and subsequent Ca2+ store depletion activate STIM (stromal interaction molecules) proteins, sensors of intraluminal Ca2+, which, in turn, open the Orai channels in plasma membrane. Downstream to this process could be activated TRPC (transient receptor potential-canonical) calcium permeable channels. Using single channel patch-clamp technique we found that a local Ca2+ entry through TRPC1 channels activated endogenous Ca2+-activated chloride channels (CaCCs) with properties similar to Anoctamin6 (TMEM16F). Our data suggest that their outward rectification is based on the dependence from membrane potential of both the channel conductance and the channel activity: (1) The conductance of active CaCCs highly depends on the transmembrane potential (from 3 pS at negative potentials till 60 pS at positive potentials); (2) their activity (NPo) is enhanced with increasing Ca2+ concentration and/or transmembrane potential, conversely lowering of intracellular Ca2+ concentration reduced the open state dwell time; (3) CaCC amplitude is only slightly increased by intracellular Ca2+ concentration. Experiments with Ca2+ buffering by EGTA or BAPTA suggest close local arrangement of functional CaCCs and TRPC1 channels. It is supposed that Ca2+-activated chloride channels are involved in Ca2+ entry microdomains.
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Affiliation(s)
| | | | | | | | - Elena Kaznacheyeva
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Avenue, 194064 St. Petersburg, Russia; (D.K.); (A.P.); (K.G.); (L.G.)
| | - Alexey Shalygin
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Avenue, 194064 St. Petersburg, Russia; (D.K.); (A.P.); (K.G.); (L.G.)
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17
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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: 50] [Impact Index Per Article: 16.7] [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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18
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Divalent Cation Modulation of Ion Permeation in TMEM16 Proteins. Int J Mol Sci 2021; 22:ijms22042209. [PMID: 33672260 PMCID: PMC7926781 DOI: 10.3390/ijms22042209] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 02/15/2021] [Accepted: 02/18/2021] [Indexed: 01/01/2023] Open
Abstract
Intracellular divalent cations control the molecular function of transmembrane protein 16 (TMEM16) family members. Both anion channels (such as TMEM16A) and phospholipid scramblases (such as TMEM16F) in this family are activated by intracellular Ca2+ in the low µM range. In addition, intracellular Ca2+ or Co2+ at mM concentrations have been shown to further potentiate the saturated Ca2+-activated current of TMEM16A. In this study, we found that all alkaline earth divalent cations in mM concentrations can generate similar potentiation effects in TMEM16A when applied intracellularly, and that manipulations thought to deplete membrane phospholipids weaken the effect. In comparison, mM concentrations of divalent cations minimally potentiate the current of TMEM16F but significantly change its cation/anion selectivity. We suggest that divalent cations may increase local concentrations of permeant ions via a change in pore electrostatic potential, possibly acting through phospholipid head groups in or near the pore. Monovalent cations appear to exert a similar effect, although with a much lower affinity. Our findings resolve controversies regarding the ion selectivity of TMEM16 proteins. The physiological role of this mechanism, however, remains elusive because of the nearly constant high cation concentrations in cytosols.
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19
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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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20
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Fernández DI, Kuijpers MJE, Heemskerk JWM. Platelet calcium signaling by G-protein coupled and ITAM-linked receptors regulating anoctamin-6 and procoagulant activity. Platelets 2020; 32:863-871. [PMID: 33356720 DOI: 10.1080/09537104.2020.1859103] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Most agonists stimulate platelet Ca2+ rises via G-protein coupled receptors (GPCRs) or ITAM-linked receptors (ILRs). Well studied are the GPCRs stimulated by the soluble agonists thrombin (PAR1, PAR4), ADP (P2Y1, P2Y12), and thromboxane A2 (TP), signaling via phospholipase (PLC)β isoforms. The platelet ILRs glycoprotein VI (GPVI), C-type lectin-like receptor 2 (CLEC2), and FcγRIIa are stimulated by adhesive ligands or antibody complexes and signal via tyrosine protein kinases and PLCγ isoforms. Marked differences exist between the GPCR- and ILR-induced Ca2+ signaling in: (i) dependency of tyrosine phosphorylation; (ii) oscillatory versus continued Ca2+ rises by mobilization from the endoplasmic reticulum; and (iii) smaller or larger role of extracellular Ca2+ entry via STIM1/ORAI1. Co-stimulation of both types of receptors, especially by thrombin (PAR1/4) and collagen (GPVI), leads to a highly enforced Ca2+ rise, involving mitochondrial Ca2+ release, which activates the ion and phospholipid channel, anoctamin-6. This highly Ca2+-dependent process causes swelling, ballooning, and phosphatidylserine expression, establishing a unique platelet population swinging between vital and necrotic (procoagulant 'zombie' platelets). Additionally, the high Ca2+ status of procoagulant platelets induces a set of additional events: (i) Ca2+ dependent cleavage of signaling proteins and receptors via calpain and ADAM isoforms; (ii) microvesiculation; (iii) enhanced coagulation factor binding; and (iv) fibrin-coat formation involving transglutaminases. Given the additive roles of GPCR and ILR in Ca2+ signal generation, high-throughput screening of biomolecules or small molecules based on Ca2+ flux measurements provides a promising way to find new inhibitors interfering with prolonged high Ca2+, phosphatidylserine expression, and hence platelet procoagulant activity.
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Affiliation(s)
- Delia I Fernández
- Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, The Netherlands
| | - Marijke J E Kuijpers
- Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, The Netherlands
| | - Johan W M Heemskerk
- Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, The Netherlands
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21
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Feng S, Dang S, Han TW, Ye W, Jin P, Cheng T, Li J, Jan YN, Jan LY, Cheng Y. Cryo-EM Studies of TMEM16F Calcium-Activated Ion Channel Suggest Features Important for Lipid Scrambling. Cell Rep 2020; 28:567-579.e4. [PMID: 31291589 PMCID: PMC6684876 DOI: 10.1016/j.celrep.2019.06.023] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2019] [Revised: 05/03/2019] [Accepted: 06/05/2019] [Indexed: 12/25/2022] Open
Abstract
As a Ca2+-activated lipid scramblase and ion channel that mediates Ca2+ influx, TMEM16F relies on both functions to facilitate extracellular vesicle generation, blood coagulation, and bone formation. How a bona fide ion channel scrambles lipids remains elusive. Our structural analyses revealed the coexistence of an intact channel pore and PIP2-dependent protein conformation changes leading to membrane distortion. Correlated to the extent of membrane distortion, many tightly bound lipids are slanted. Structure-based mutagenesis studies further reveal that neutralization of some lipid-binding residues or those near membrane distortion specifically alters the onset of lipid scrambling, but not Ca2+ influx, thus identifying features outside of channel pore that are important for lipid scrambling. Together, our studies demonstrate that membrane distortion does not require open hydrophilic grooves facing the membrane interior and provide further evidence to suggest separate pathways for lipid scrambling and ion permeation. TMEM16F is a calcium-activated ion channel and lipid scramblase linked to the bleeding disorder Scott syndrome. Feng et al. examine cryo-EM structures of TMEM16F with or without Ca2+ ions and PIP2 nanodisc supplementation and identify structural features for lipid binding and membrane distortion critical for lipid scrambling activity.
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Affiliation(s)
- Shengjie Feng
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Shangyu Dang
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Tina Wei Han
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Wenlei Ye
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Peng Jin
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Tong Cheng
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Junrui Li
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Yuh Nung Jan
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94158, USA; Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA; Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Lily Yeh Jan
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94158, USA; Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA; Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158, USA.
| | - Yifan Cheng
- Department of Biochemistry and Biophysics, 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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22
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Wilke BU, Kummer KK, Leitner MG, Kress M. Chloride - The Underrated Ion in Nociceptors. Front Neurosci 2020; 14:287. [PMID: 32322187 PMCID: PMC7158864 DOI: 10.3389/fnins.2020.00287] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2019] [Accepted: 03/12/2020] [Indexed: 01/06/2023] Open
Abstract
In contrast to pain processing neurons in the spinal cord, where the importance of chloride conductances is already well established, chloride homeostasis in primary afferent neurons has received less attention. Sensory neurons maintain high intracellular chloride concentrations through balanced activity of Na+-K+-2Cl– cotransporter 1 (NKCC1) and K+-Cl– cotransporter 2 (KCC2). Whereas in other cell types activation of chloride conductances causes hyperpolarization, activation of the same conductances in primary afferent neurons may lead to inhibitory or excitatory depolarization depending on the actual chloride reversal potential and the total amount of chloride efflux during channel or transporter activation. Dorsal root ganglion (DRG) neurons express a multitude of chloride channel types belonging to different channel families, such as ligand-gated, ionotropic γ-aminobutyric acid (GABA) or glycine receptors, Ca2+-activated chloride channels of the anoctamin/TMEM16, bestrophin or tweety-homolog family, CLC chloride channels and transporters, cystic fibrosis transmembrane conductance regulator (CFTR) as well as volume-regulated anion channels (VRACs). Specific chloride conductances are involved in signal transduction and amplification at the peripheral nerve terminal, contribute to excitability and action potential generation of sensory neurons, or crucially shape synaptic transmission in the spinal dorsal horn. In addition, chloride channels can be modified by a plethora of inflammatory mediators affecting them directly, via protein-protein interaction, or through signaling cascades. Since chloride channels as well as mediators that modulate chloride fluxes are regulated in pain disorders and contribute to nociceptor excitation and sensitization it is timely and important to emphasize their critical role in nociceptive primary afferents in this review.
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Affiliation(s)
- Bettina U Wilke
- Institute of Physiology, Department of Physiology and Medical Physics, Medical University of Innsbruck, Innsbruck, Austria
| | - Kai K Kummer
- Institute of Physiology, Department of Physiology and Medical Physics, Medical University of Innsbruck, Innsbruck, Austria
| | - Michael G Leitner
- Institute of Physiology, Department of Physiology and Medical Physics, Medical University of Innsbruck, Innsbruck, Austria
| | - Michaela Kress
- Institute of Physiology, Department of Physiology and Medical Physics, Medical University of Innsbruck, Innsbruck, Austria
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23
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Wu N, Cernysiov V, Davidson D, Song H, Tang J, Luo S, Lu Y, Qian J, Gyurova IE, Waggoner SN, Trinh VQH, Cayrol R, Sugiura A, McBride HM, Daudelin JF, Labrecque N, Veillette A. Critical Role of Lipid Scramblase TMEM16F in Phosphatidylserine Exposure and Repair of Plasma Membrane after Pore Formation. Cell Rep 2020; 30:1129-1140.e5. [PMID: 31995754 PMCID: PMC7104872 DOI: 10.1016/j.celrep.2019.12.066] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 10/25/2019] [Accepted: 12/17/2019] [Indexed: 01/01/2023] Open
Abstract
Plasma membrane damage and cell death during processes such as necroptosis and apoptosis result from cues originating intracellularly. However, death caused by pore-forming agents, like bacterial toxins or complement, is due to direct external injury to the plasma membrane. To prevent death, the plasma membrane has an intrinsic repair ability. Here, we found that repair triggered by pore-forming agents involved TMEM16F, a calcium-activated lipid scramblase also mutated in Scott's syndrome. Upon pore formation and the subsequent influx of intracellular calcium, TMEM16F induced rapid "lipid scrambling" in the plasma membrane. This response was accompanied by membrane blebbing, extracellular vesicle release, preserved membrane integrity, and increased cell viability. TMEM16F-deficient mice exhibited compromised control of infection by Listeria monocytogenes associated with a greater sensitivity of neutrophils to the pore-forming Listeria toxin listeriolysin O (LLO). Thus, the lipid scramblase TMEM16F is critical for plasma membrane repair after injury by pore-forming agents.
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Affiliation(s)
- Ning Wu
- Laboratory of Molecular Oncology, Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC H2W1R7, Canada; Department of Immunology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology (HUST), Wuhan, China; Department of Rheumatology and Immunology, Tongji Hospital, Huazhong University of Science and Technology (HUST), Wuhan, China.
| | - Vitalij Cernysiov
- Laboratory of Molecular Oncology, Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC H2W1R7, Canada
| | - Dominique Davidson
- Laboratory of Molecular Oncology, Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC H2W1R7, Canada
| | - Hua Song
- Department of Immunology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology (HUST), Wuhan, China
| | - Jianlong Tang
- Department of Immunology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology (HUST), Wuhan, China
| | - Shanshan Luo
- Institute of Hematology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology (HUST), Wuhan, China
| | - Yan Lu
- Laboratory of Molecular Oncology, Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC H2W1R7, Canada
| | - Jin Qian
- Laboratory of Molecular Oncology, Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC H2W1R7, Canada
| | - Ivayla E Gyurova
- Center for Autoimmune Genomics and Etiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA; Pathobiology and Molecular Medicine Graduate Program, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Stephen N Waggoner
- Center for Autoimmune Genomics and Etiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA; Pathobiology and Molecular Medicine Graduate Program, University of Cincinnati College of Medicine, Cincinnati, OH, USA; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Vincent Quoc-Huy Trinh
- Department of Pathology and Cellular Biology, University of Montreal, Montreal, QC, Canada
| | - Romain Cayrol
- Department of Pathology and Cellular Biology, University of Montreal, Montreal, QC, Canada
| | - Ayumu Sugiura
- Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada
| | - Heidi M McBride
- Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada
| | | | - Nathalie Labrecque
- Maisonneuve-Rosemont Hospital Research Center, Montréal, QC, Canada; Department of Medicine, University of Montréal, Montréal, QC H3C3J7, Canada; Department of Microbiology, Infectious Diseases and Immunology, University of Montréal, Montréal, QC H3C3J7, Canada
| | - André Veillette
- Laboratory of Molecular Oncology, Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC H2W1R7, Canada; Maisonneuve-Rosemont Hospital Research Center, Montréal, QC, Canada; Department of Medicine, McGill University, Montréal, QC H3G 1Y6, Canada.
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