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Pumroy RA, Fluck EC, Ahmed T, Moiseenkova-Bell VY. Structural insights into the gating mechanisms of TRPV channels. Cell Calcium 2020; 87:102168. [PMID: 32004816 DOI: 10.1016/j.ceca.2020.102168] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 01/22/2020] [Accepted: 01/22/2020] [Indexed: 02/06/2023]
Abstract
Transient Receptor Potential channels from the vanilloid subfamily (TRPV) are a group of cation channels modulated by a variety of endogenous stimuli as well as a range of natural and synthetic compounds. Their roles in human health make them of keen interest, particularly from a pharmacological perspective. However, despite this interest, the complexity of these channels has made it difficult to obtain high resolution structures until recently. With the cryo-EM resolution revolution, TRPV channel structural biology has blossomed to produce dozens of structures, covering every TRPV family member and a variety of approaches to examining channel modulation. Here, we review all currently available TRPV structures and the mechanistic insights into gating that they reveal.
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Affiliation(s)
- Ruth A Pumroy
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, 19104, USA
| | - Edwin C Fluck
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, 19104, USA
| | - Tofayel Ahmed
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, 19104, USA
| | - Vera Y Moiseenkova-Bell
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, 19104, USA.
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2
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Abstract
Transient receptor potential (TRP) ion channels are molecular sensors of a large variety of stimuli including temperature, mechanical stress, voltage, small molecules including capsaicin and menthol, and lipids such as phosphatidylinositol 4,5-bisphosphate (PIP2). Since the same TRP channels may respond to different physical and chemical stimuli, they can serve as signal integrators. Many TRP channels are calcium permeable and contribute to Ca2+ homeostasis and signaling. Although the TRP channel family was discovered decades ago, only recently have the structures of many of these channels been solved, largely by cryo-electron microscopy (cryo-EM). Complimentary to cryo-EM, X-ray crystallography provides unique tools to unambiguously identify specific atoms and can be used to study ion binding in channel pores. In this review we describe crystallographic studies of the TRP channel TRPV6. The methodology used in these studies may serve as a template for future structural analyses of different types of TRP and other ion channels.
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Affiliation(s)
- Appu K Singh
- a Department of Biochemistry and Molecular Biophysics , Columbia University , New York , NY
| | - Luke L McGoldrick
- a Department of Biochemistry and Molecular Biophysics , Columbia University , New York , NY.,b Integrated Program in Cellular, Molecular and Biomedical Studies, Columbia University , New York , NY
| | - Kei Saotome
- a Department of Biochemistry and Molecular Biophysics , Columbia University , New York , NY
| | - Alexander I Sobolevsky
- a Department of Biochemistry and Molecular Biophysics , Columbia University , New York , NY
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3
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Vangeel L, Voets T. Transient Receptor Potential Channels and Calcium Signaling. Cold Spring Harb Perspect Biol 2019; 11:cshperspect.a035048. [PMID: 30910771 DOI: 10.1101/cshperspect.a035048] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Transient receptor potential (TRP) cation channels play diverse roles in cellular Ca2+ signaling. First, as Ca2+-permeable channels that respond to a variety of stimuli, TRP channels can directly initiate cellular Ca2+ signals. Second, as nonselective cation channels, TRP channel activation leads to membrane depolarization, influencing Ca2+ influx via voltage-gated and store-operated Ca2+ channels. Finally, Ca2+ modulates the activity of most TRP channels, allowing them to function as molecular effectors downstream of intracellular Ca2+ signals. Whereas the TRP channel field has long been devoid of detailed channel structures, recent advances, particularly in cryo-electron microscopy-based structural approaches, have yielded a flurry of TRP channel structures, including members from all seven subfamilies. These structures, in conjunction with mutagenesis-based functional approaches, provided important new insights into the mechanisms whereby TRP channels permeate and sense Ca2+ These insights will be highly instrumental in the rational design of novel treatments for the multitude of TRP channel-related diseases.
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Affiliation(s)
- Laura Vangeel
- Laboratory of Ion Channel Research, VIB Center for Brain and Disease Research & Department of Cellular and Molecular Medicine, University of Leuven, B-3000 Leuven, Belgium
| | - Thomas Voets
- Laboratory of Ion Channel Research, VIB Center for Brain and Disease Research & Department of Cellular and Molecular Medicine, University of Leuven, B-3000 Leuven, Belgium
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4
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Analgesic Activity of Hexaazaisowurtzitane Derivatives. Bull Exp Biol Med 2019; 166:461-465. [DOI: 10.1007/s10517-019-04372-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Indexed: 11/30/2022]
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5
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Singh AK, McGoldrick LL, Sobolevsky AI. Expression, Purification, and Crystallization of the Transient Receptor Potential Channel TRPV6. Methods Mol Biol 2019; 1987:23-37. [PMID: 31028671 DOI: 10.1007/978-1-4939-9446-5_2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Transient receptor potential (TRP) channels are polymodal sensory transducers that respond to chemicals, temperature, mechanical stress, and membrane voltage and are involved in vision, taste, olfaction, hearing, touch, thermal perception, and nociception. TRP channels are implicated in numerous devastating diseases, including various forms of cancer, and represent important drug targets. The large sizes, low expression levels, and conformational dynamics of TRP channels make them challenging targets for structural biology. Here, we present the methodology used in structural studies of TRPV6, a TRP channel that is highly selective for calcium and mediates Ca2+ uptake in epithelial tissues. We provide a protocol for the expression, purification, and crystallization of TRPV6. Similar approaches can be used to determine crystal structures of other membrane proteins, including different members of the TRP channel family.
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Affiliation(s)
- Appu K Singh
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA
| | - Luke L McGoldrick
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA.,Integrated Program in Cellular, Molecular and Biomedical Studies, Columbia University, New York, NY, USA
| | - Alexander I Sobolevsky
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA.
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6
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Dunstone MA, de Marco A. Cryo-electron tomography: an ideal method to study membrane-associated proteins. Philos Trans R Soc Lond B Biol Sci 2018. [PMID: 28630150 DOI: 10.1098/rstb.2016.0210] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Cryo-electron tomography (cryo-ET) is a three-dimensional imaging technique that makes it possible to analyse the structure of complex and dynamic biological assemblies in their native conditions. The latest technological and image processing developments demonstrate that it is possible to obtain structural information at nanometre resolution. The sample preparation required for the cryo-ET technique does not require the isolation of a protein and other macromolecular complexes from its native environment. Therefore, cryo-ET is emerging as an important tool to study the structure of membrane-associated proteins including pores.This article is part of the themed issue 'Membrane pores: from structure and assembly, to medicine and technology'.
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Affiliation(s)
- Michelle A Dunstone
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton Campus, Melbourne, Victoria 3800, Australia.,ARC Centre of Excellence in Advanced Molecular Imaging, Monash University, Clayton Campus, Melbourne, Victoria 3800, Australia.,Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton Campus, Melbourne, Victoria 3800, Australia
| | - Alex de Marco
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton Campus, Melbourne, Victoria 3800, Australia .,ARC Centre of Excellence in Advanced Molecular Imaging, Monash University, Clayton Campus, Melbourne, Victoria 3800, Australia
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7
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Madej MG, Ziegler CM. Dawning of a new era in TRP channel structural biology by cryo-electron microscopy. Pflugers Arch 2018; 470:213-225. [PMID: 29344776 DOI: 10.1007/s00424-018-2107-2] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Accepted: 01/03/2018] [Indexed: 12/20/2022]
Abstract
Cryo-electron microscopy (cryo-EM) permits the determination of atomic protein structures by averaging large numbers of individual projection images recorded at cryogenic temperatures-a method termed single-particle analysis. The cryo-preservation traps proteins within a thin glass-like ice layer, making literally a freeze image of proteins in solution. Projections of randomly adopted orientations are merged to reconstruct a 3D density map. While atomic resolution for highly symmetric viruses was achieved already in 2009, the development of new sensitive and fast electron detectors has enabled cryo-EM for smaller and asymmetrical proteins including fragile membrane proteins. As one of the most important structural biology methods at present, cryo-EM was awarded in October 2017 with the Nobel Prize in Chemistry. The molecular understanding of Transient-Receptor-Potential (TRP) channels has been boosted tremendously by cryo-EM single-particle analysis. Several near-atomic and atomic structures gave important mechanistic insights, e.g., into ion permeation and selectivity, gating, as well as into the activation of this enigmatic and medically important membrane protein family by various chemical and physical stimuli. Lastly, these structures have set the starting point for the rational design of TRP channel-targeted therapeutics to counteract life-threatening channelopathies. Here, we attempt a brief introduction to the method, review the latest advances in cryo-EM structure determination of TRP channels, and discuss molecular insights into the channel function based on the wealth of TRP channel cryo-EM structures.
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Affiliation(s)
- M Gregor Madej
- Department of Structural Biology, Institute of Biophysics and Physical Biochemistry, University of Regensburg, Universitätsstrasse 31, D-93053, Regensburg, Germany
| | - Christine M Ziegler
- Department of Structural Biology, Institute of Biophysics and Physical Biochemistry, University of Regensburg, Universitätsstrasse 31, D-93053, Regensburg, Germany.
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8
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Fujita T, Liu Y, Higashitsuji H, Itoh K, Shibasaki K, Fujita J, Nishiyama H. Involvement of TRPV3 and TRPM8 ion channel proteins in induction of mammalian cold-inducible proteins. Biochem Biophys Res Commun 2018; 495:935-940. [DOI: 10.1016/j.bbrc.2017.11.136] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 11/20/2017] [Indexed: 12/15/2022]
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9
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Abstract
Supplemental Digital Content is Available in the Text. The approved antiepileptic drug primidone potently inhibits TRPM3 channels and thereby exerts analgesic properties to chemical pain and thermal hyperalgesia in mice. The melastatin-related transient receptor potential (TRP) channel TRPM3 is a nonselective cation channel expressed in nociceptive neurons and activated by heat. Because TRPM3-deficient mice show inflammatory thermal hyperalgesia, pharmacological inhibition of TRPM3 may exert antinociceptive properties. Fluorometric Ca2+ influx assays and a compound library containing approved or clinically tested drugs were used to identify TRPM3 inhibitors. Biophysical properties of channel inhibition were assessed using electrophysiological methods. The nonsteroidal anti-inflammatory drug diclofenac, the tetracyclic antidepressant maprotiline, and the anticonvulsant primidone were identified as highly efficient TRPM3 blockers with half-maximal inhibition at 0.6 to 6 μM and marked specificity for TRPM3. Most prominently, primidone was biologically active to suppress TRPM3 activation by pregnenolone sulfate (PregS) and heat at concentrations markedly lower than plasma concentrations commonly used in antiepileptic therapy. Primidone blocked PregS-induced Ca2+i influx through TRPM3 by allosteric modulation and reversibly inhibited atypical inwardly rectifying TRPM3 currents induced by coapplication of PregS and clotrimazole. In vivo, analgesic effects of low doses of primidone were demonstrated in mice, applying PregS- and heat-induced pain models, including inflammatory hyperalgesia. Thus, applying the approved drug at concentrations that are lower than those needed to induce anticonvulsive effects offers a shortcut for studying physiological and pathophysiological roles of TRPM3 in vivo.
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10
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Wang G, Wang K. The Ca2+-Permeable Cation Transient Receptor Potential TRPV3 Channel: An Emerging Pivotal Target for Itch and Skin Diseases. Mol Pharmacol 2017; 92:193-200. [DOI: 10.1124/mol.116.107946] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Accepted: 03/31/2017] [Indexed: 12/15/2022] Open
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11
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De Toni L, Garolla A, Menegazzo M, Magagna S, Di Nisio A, Šabović I, Rocca MS, Scattolini V, Filippi A, Foresta C. Heat Sensing Receptor TRPV1 Is a Mediator of Thermotaxis in Human Spermatozoa. PLoS One 2016; 11:e0167622. [PMID: 27992447 PMCID: PMC5161326 DOI: 10.1371/journal.pone.0167622] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Accepted: 11/17/2016] [Indexed: 01/13/2023] Open
Abstract
The molecular bases of sperm thermotaxis, the temperature-oriented cell motility, are currently under investigation. Thermal perception relies on a subclass of the transient receptor potential [TRP] channels, whose member TRPV1 is acknowledged as the heat sensing receptor. Here we investigated the involvement of TRPV1 in human sperm thermotaxis. We obtained semen samples from 16 normozoospermic subjects attending an infertility survey programme, testis biopsies from 6 patients with testicular germ cell cancer and testis fine needle aspirates from 6 patients with obstructive azoospermia undergoing assisted reproductive technologies. Expression of TRPV1 mRNA was assessed by RT-PCR. Protein expression of TRPV1 was determined by western blot, flow cytometry and immunofluorescence. Sperm motility was assessed by Sperm Class Analyser. Acrosome reaction, apoptosis and intracellular-Ca2+ content were assessed by flow cytometry. We found that TRPV1 mRNA and protein were highly expressed in the testis, in both Sertoli cells and germ-line cells. Moreover, compared to no-gradient controls at 31°C or 37°C (Ctrl 31°C and Ctrl 37°C respectively), sperm migration towards a temperature gradient of 31–37°C (T gradient) in non-capacitated conditions selected a higher number of cells (14,9 ± 4,2×106 cells T gradient vs 5,1± 0,3×106 cells Ctrl 31°C and 5,71±0,74×106 cells Ctrl 37°C; P = 0,039). Capacitation amplified the migrating capability towards the T gradient. Sperms migrated towards the T gradient showed enriched levels of both TRPV1 protein and mRNA. In addition, sperm cells were able to migrate toward a gradient of capsaicin, a specific agonist of TRPV1, whilst capsazepine, a specific agonist of TRPV1, blocked this effect. Finally, capsazepine severely blunted migration towards T gradient without abolishing. These results suggest that TRPV1 may represent a facilitating mediator of sperm thermotaxis.
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Affiliation(s)
- Luca De Toni
- Department of Medicine, Unit of Andrology and Reproductive Medicine, University of Padova, Via Giustiniani, Padova, Italy
| | - Andrea Garolla
- Department of Medicine, Unit of Andrology and Reproductive Medicine, University of Padova, Via Giustiniani, Padova, Italy
| | - Massimo Menegazzo
- Department of Medicine, Unit of Andrology and Reproductive Medicine, University of Padova, Via Giustiniani, Padova, Italy
| | - Sabina Magagna
- Department of Medicine, Unit of Andrology and Reproductive Medicine, University of Padova, Via Giustiniani, Padova, Italy
| | - Andrea Di Nisio
- Department of Medicine, Unit of Andrology and Reproductive Medicine, University of Padova, Via Giustiniani, Padova, Italy
| | - Iva Šabović
- Department of Medicine, Unit of Andrology and Reproductive Medicine, University of Padova, Via Giustiniani, Padova, Italy
- IRCCS-Istituto Oncologico Veneto [IOV], Via Gattamelata, Padova, Italy
| | - Maria Santa Rocca
- Department of Medicine, Unit of Andrology and Reproductive Medicine, University of Padova, Via Giustiniani, Padova, Italy
| | - Valentina Scattolini
- Department of Medicine, University of Padova, Via Giustiniani, Padova, Italy
- Venetian Institute of Molecular Medicine, Via Orus 2, Padova, Italy
| | - Andrea Filippi
- Department of Physics and Astronomy “G. Galilei”, University of Padova, Via Marzolo 8, Padova, Italy
| | - Carlo Foresta
- Department of Medicine, Unit of Andrology and Reproductive Medicine, University of Padova, Via Giustiniani, Padova, Italy
- * E-mail:
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12
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Vinothkumar KR. Membrane protein structures without crystals, by single particle electron cryomicroscopy. Curr Opin Struct Biol 2015; 33:103-14. [PMID: 26435463 PMCID: PMC4764762 DOI: 10.1016/j.sbi.2015.07.009] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 07/13/2015] [Accepted: 07/24/2015] [Indexed: 11/25/2022]
Abstract
Electron microscopy of membrane proteins as single particles. Membrane protein structures without crystals. Direct electron detectors have high signal to noise. Medium to high-resolution structures of molecules between 0.13 and 2 MDa. Sub-tomogram averaging to study membrane proteins in situ.
It is an exciting period in membrane protein structural biology with a number of medically important protein structures determined at a rapid pace. However, two major hurdles still remain in the structural biology of membrane proteins. One is the inability to obtain large amounts of protein for crystallization and the other is the failure to get well-diffracting crystals. With single particle electron cryomicroscopy, both these problems can be overcome and high-resolution structures of membrane proteins and other labile protein complexes can be obtained with very little protein and without the need for crystals. In this review, I highlight recent advances in electron microscopy, detectors and software, which have allowed determination of medium to high-resolution structures of membrane proteins and complexes that have been difficult to study by other structural biological techniques.
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Affiliation(s)
- Kutti R Vinothkumar
- Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, United Kingdom.
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13
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Huynh KW, Cohen MR, Moiseenkova-Bell VY. Application of amphipols for structure-functional analysis of TRP channels. J Membr Biol 2014; 247:843-51. [PMID: 24894720 DOI: 10.1007/s00232-014-9684-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Accepted: 05/13/2014] [Indexed: 11/25/2022]
Abstract
Amphipathic polymers (amphipols), such as A8-35 and SApol, are a new tool for stabilizing integral membrane proteins in detergent-free conditions for structural and functional studies. Transient receptor potential (TRP) ion channels function as tetrameric protein complexes in a diverse range of cellular processes including sensory transduction. Mammalian TRP channels share ~20 % sequence similarity and are categorized into six subfamilies: TRPC (canonical), TRPV (vanilloid), TRPA (ankyrin), TRPM (melastatin), TRPP (polycystin), and TRPML (mucolipin). Due to the inherent difficulties in purifying eukaryotic membrane proteins, structural studies of TRP channels have been limited. Recently, A8-35 was essential in resolving the molecular architecture of the nociceptor TRPA1 and led to the determination of a high-resolution structure of the thermosensitive TRPV1 channel by cryo-EM. Newly developed maltose-neopentyl glycol (MNG) detergents have also proven to be useful in stabilizing TRP channels for structural analysis. In this review, we will discuss the impacts of amphipols and MNG detergents on structural studies of TRP channels by cryo-EM. We will compare how A8-35 and MNG detergents interact with the hydrophobic transmembrane domains of TRP channels. In addition, we will discuss what these cryo-EM studies reveal on the importance of screening different types of surfactants toward determining high-resolution structures of TRP channels.
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Affiliation(s)
- Kevin W Huynh
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
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14
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Peckys DB, de Jonge N. Liquid scanning transmission electron microscopy: imaging protein complexes in their native environment in whole eukaryotic cells. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2014; 20:346-65. [PMID: 24548636 DOI: 10.1017/s1431927614000099] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Scanning transmission electron microscopy (STEM) of specimens in liquid, so-called Liquid STEM, is capable of imaging the individual subunits of macromolecular complexes in whole eukaryotic cells in liquid. This paper discusses this new microscopy modality within the context of state-of-the-art microscopy of cells. The principle of operation and equations for the resolution are described. The obtained images are different from those acquired with standard transmission electron microscopy showing the cellular ultrastructure. Instead, contrast is obtained on specific labels. Images can be recorded in two ways, either via STEM at 200 keV electron beam energy using a microfluidic chamber enclosing the cells, or via environmental scanning electron microscopy at 30 keV of cells in a wet environment. The first series of experiments involved the epidermal growth factor receptor labeled with gold nanoparticles. The labels were imaged in whole fixed cells with nanometer resolution. Since the cells can be kept alive in the microfluidic chamber, it is also feasible to detect the labels in unfixed, live cells. The rapid sample preparation and imaging allows studies of multiple whole cells.
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Affiliation(s)
- Diana B Peckys
- 1 Leibniz Institute for New Materials (INM), 66123 Saarbrücken, Germany
| | - Niels de Jonge
- 1 Leibniz Institute for New Materials (INM), 66123 Saarbrücken, Germany
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15
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Abstract
Membrane proteins remain challenging targets for structural biologists, despite recent technical developments regarding sample preparation and structure determination. We review recent progress towards a structural understanding of TRP channels and the techniques used to that end. We discuss available low-resolution structures from electron microscopy (EM), X-ray crystallography, and nuclear magnetic resonance (NMR) and review the resulting insights into TRP channel function for various subfamily members. The recent high-resolution structure of TRPV1 is discussed in more detail in Chapter 11. We also consider the opportunities and challenges of using the accumulating structural information on TRPs and homologous proteins for deducing full-length structures of different TRP channel subfamilies, such as building homology models. Finally, we close by summarizing the outlook of the "holy grail" of understanding in atomic detail the diverse functions of TRP channels.
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16
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Cohen MR, Moiseenkova-Bell VY. Structure of thermally activated TRP channels. CURRENT TOPICS IN MEMBRANES 2014; 74:181-211. [PMID: 25366237 DOI: 10.1016/b978-0-12-800181-3.00007-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Temperature sensation is important for adaptation and survival of organisms. While temperature has the potential to affect all biological macromolecules, organisms have evolved specific thermosensitive molecular detectors that are able to transduce temperature changes into physiologically relevant signals. Among these thermosensors are ion channels from the transient receptor potential (TRP) family. Prime candidates include TRPV1-4, TRPA1, and TRPM8 (the so-called "thermoTRP" channels), which are expressed in sensory neurons and gated at specific temperatures. Electrophysiological and thermodynamic approaches have been employed to determine the nature by which thermoTRPs detect temperature and couple temperature changes to channel gating. To further understand how thermoTRPs sense temperature, high-resolution structures of full-length thermoTRPs channels will be required. Here, we will discuss current progress in unraveling the structures of thermoTRP channels.
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Affiliation(s)
- Matthew R Cohen
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, OH, USA; Department of Physiology & Biophysics, Case Western Reserve University School of Medicine, Cleveland, OH, USA
| | - Vera Y Moiseenkova-Bell
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, OH, USA; Department of Physiology & Biophysics, Case Western Reserve University School of Medicine, Cleveland, OH, USA
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17
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TRPM4 channels in smooth muscle function. Pflugers Arch 2013; 465:1223-31. [PMID: 23443854 DOI: 10.1007/s00424-013-1250-z] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Revised: 02/08/2013] [Accepted: 02/09/2013] [Indexed: 01/03/2023]
Abstract
The melastatin (M) transient receptor potential (TRP) channel TRPM4 is selective for monovalent cations and is activated by high levels of intracellular Ca(2+). TRPM4 is broadly distributed and may be involved in numerous functions, including electrical conduction in the heart, respiratory rhythm, immune response, and secretion of insulin by pancreatic β-cells. The significance of TRPM4 in smooth muscle cell function is reviewed here. Several studies indicate that TRPM4 channels are critically important for pressure-induced cerebral arterial myocyte depolarization and myogenic vasoconstriction as well as autoregulation of cerebral blood flow. Regulation of TRPM4 activity in arterial smooth muscle cells is complex and involves release of Ca(2+) from the sarcoplasmic reticulum through inositol 1,4,5-trisphosphate receptors and translocation of TRPM4 channels to the plasma membrane in response to protein kinase Cδ. TRPM4 is also present in colonic, urinary bladder, aortic, interlobar pulmonary and renal artery, airway, and corpus cavernosum smooth muscle cells, but its significance and regulation in these tissues is less well characterized.
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18
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Zelepuga EA, Tabakmakher VM, Chausova VE, monastyrnaia MM, Isaeva MP, Kozlovskaia ÉP. [Interaction of sea amemone Heteractis crispa Kunitz type polypeptides with pain vanilloid receptor TRPV1: in silico investigation]. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2012; 38:185-98. [PMID: 22792722 DOI: 10.1134/s106816201202015x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Using methods of molecular biology we defined the structures of the 31 sea anemone Heteractis crispa genes encoding polypeptides which are structurally homologous to the Kunitz proteinase inhibitor family. Identified amino acid sequences have point residue substitutions, high degree of homology with sequences of known H. crispa Kunitz family members, and represent a combinatorial library of polypeptides. We generated their three-dimensional structures by homologous modeling methods. Analysis of their molecular electrostatic potential enabled us to divide given polypeptides into three clusters. One of them includes polypeptides APHC1, APHC2 and APHC3, which were earlier shown to possess a unique property of inhibiting of the pain vanilloid receptor TRPV1 in vitro and providing the analgesic effects in vivo in addition to their trypsin inhibitory activity. Molecular docking made possible establishing the spatial structure of the complexes, the nature of the polypeptides binding with TRPV1, as well as functionally important structural elements involved in the complex formation. Structural models have enabled us to propose a hypothesis contributing to understanding the APHC1-3 impact mechanism for the pain signals transduction by TRPV1: apparently, there is an increase of the receptor relaxation time resulted in binding of its two chains with the polypeptide molecule, which disrupt the functioning of the TRPV1 and leads to partial inhibition of signal transduction in electrophysiological experiments.
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19
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Frühwald J, Camacho Londoño J, Dembla S, Mannebach S, Lis A, Drews A, Wissenbach U, Oberwinkler J, Philipp SE. Alternative splicing of a protein domain indispensable for function of transient receptor potential melastatin 3 (TRPM3) ion channels. J Biol Chem 2012; 287:36663-72. [PMID: 22961981 DOI: 10.1074/jbc.m112.396663] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
TRPM3 channels form ionotropic steroid receptors in the plasma membrane of pancreatic β and dorsal root ganglion cells and link steroid hormone signaling to insulin release and pain perception, respectively. We identified and compared the function of a number of TRPM3 splice variants present in mouse, rat and human tissues. We found that variants lacking a region of 18 amino acid residues display neither Ca(2+) entry nor ionic currents when expressed alone. Hence, splicing removes a region that is indispensable for channel function, which is called the ICF region. TRPM3 variants devoid of this region (TRPM3ΔICF), are ubiquitously present in different tissues and cell types where their transcripts constitute up to 15% of the TRPM3 isoforms. The ICF region is conserved throughout the TRPM family, and its presence in TRPM8 proteins is also necessary for function. Within the ICF region, 10 amino acid residues form a domain essential for the formation of operative TRPM3 channels. TRPM3ΔICF variants showed reduced interaction with other TRPM3 isoforms, and their occurrence at the cell membrane was diminished. Correspondingly, coexpression of ΔICF proteins with functional TRPM3 subunits not only reduced the number of channels but also impaired TRPM3-mediated Ca(2+) entry. We conclude that TRPM3ΔICF variants are regulatory channel subunits fine-tuning TRPM3 channel activity.
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Affiliation(s)
- Julia Frühwald
- From the Experimentelle und Klinische Pharmakologie und Toxikologie, Universität des Saarlandes, 66421 Homburg, Germany
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Vay L, Gu C, McNaughton PA. The thermo-TRP ion channel family: properties and therapeutic implications. Br J Pharmacol 2012; 165:787-801. [PMID: 21797839 PMCID: PMC3312478 DOI: 10.1111/j.1476-5381.2011.01601.x] [Citation(s) in RCA: 208] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Revised: 04/13/2011] [Accepted: 05/01/2011] [Indexed: 01/09/2023] Open
Abstract
The thermo-transient receptor potentials (TRPs), a recently discovered family of ion channels activated by temperature, are expressed in primary sensory nerve terminals where they provide information about thermal changes in the environment. Six thermo-TRPs have been characterised to date: TRP vanilloid (TRPV) 1 and 2 are activated by painful levels of heat, TRPV3 and 4 respond to non-painful warmth, TRP melastatin 8 is activated by non-painful cool temperatures, while TRP ankyrin (TRPA) 1 is activated by painful cold. The thermal thresholds of many thermo-TRPs are known to be modulated by extracellular mediators, released by tissue damage or inflammation, such as bradykinin, PG and growth factors. There have been intensive efforts recently to develop antagonists of thermo-TRP channels, particularly of the noxious thermal sensors TRPV1 and TRPA1. Blockers of these channels are likely to have therapeutic uses as novel analgesics, but may also cause unacceptable side effects. Controlling the modulation of thermo-TRPs by inflammatory mediators may be a useful alternative strategy in developing novel analgesics.
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Affiliation(s)
- Laura Vay
- Department of Pharmacology, University of Cambridge, Cambridge, UK
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Wang L, Cvetkov TL, Chance MR, Moiseenkova-Bell VY. Identification of in vivo disulfide conformation of TRPA1 ion channel. J Biol Chem 2011; 287:6169-76. [PMID: 22207754 DOI: 10.1074/jbc.m111.329748] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
TRPA1 (transient receptor potential ankyrin 1) is an ion channel expressed in the termini of sensory neurons and is activated in response to a broad array of noxious exogenous and endogenous thiol-reactive compounds, making it a crucial player in chemical nociception. A number of conserved cysteine residues on the N-terminal domain of the channel have been identified as critical for sensing these electrophilic pungent chemicals, and our recent EM structure with modeled domains predicts that these cysteines form a ligand-binding pocket, allowing for the possibility of disulfide bonding between the cysteine residues. Here, we present a comprehensive mass spectrometry investigation of the in vivo disulfide bonding conformation and in vitro reactivity of 30 of the 31 cysteine residues in the TRPA1 ion channel. Four disulfide bonds were detected in the in vivo TRPA1 structure: Cys-666-Cys-622, Cys-666-Cys-463, Cys-622-Cys-609, and Cys-666-Cys-193. All of the cysteines detected were reactive to N-methylmaleimide (NMM) in vitro, with varying degrees of labeling efficiency. Comparison of the ratio of the labeling efficiency at 300 μM versus 2 mM NMM identified a number of cysteine residues that were outliers from the mean labeling ratio, suggesting that protein conformation changes rendered these cysteines either more or less protected from labeling at the higher NMM concentrations. These results indicate that the activation mechanism of TRPA1 may involve N-terminal conformation changes and disulfide bonding between critical cysteine residues.
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Affiliation(s)
- Liwen Wang
- Department of Pharmacology, School of Medicine, Case Western Reserve University,Cleveland, Ohio 44106, USA
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Cvetkov TL, Huynh KW, Cohen MR, Moiseenkova-Bell VY. Molecular architecture and subunit organization of TRPA1 ion channel revealed by electron microscopy. J Biol Chem 2011; 286:38168-38176. [PMID: 21908607 DOI: 10.1074/jbc.m111.288993] [Citation(s) in RCA: 97] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Transient receptor potential ankyrin 1 (TRPA1) is a non-selective ion channel, which is expressed in nociceptor sensory neurons and transduces chemical, inflammatory, and neuropathic pain signals. Numerous non-reactive compounds and electrophilic compounds, such as endogenous inflammatory mediators and exogenous pungent chemicals, can activate TRPA1. Here we report a 16-Å resolution structure of purified, functional, amphipol-stabilized TRPA1 analyzed by single-particle EM. Molecular models of the N and C termini of the channel were generated using the I-TASSER protein structure prediction server and docked into the EM density to provide insight into the TRPA1 subunit organization. This structural analysis suggests a location for critical N-terminal cysteine residues involved in electrophilic activation at the interface between neighboring subunits. Our results indicate that covalent modifications within this pocket may alter interactions between subunits and promote conformational changes that lead to channel activation.
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Affiliation(s)
- Teresa L Cvetkov
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106
| | - Kevin W Huynh
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106
| | - Matthew R Cohen
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106
| | - Vera Y Moiseenkova-Bell
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106.
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Binshtok AM. Mechanisms of nociceptive transduction and transmission: a machinery for pain sensation and tools for selective analgesia. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2011; 97:143-77. [PMID: 21708310 DOI: 10.1016/b978-0-12-385198-7.00006-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Many surgical and dental procedures depend on use of local anesthetics to reversibly eliminate pain. By the blockade of voltage-gated sodium channels, local anesthetics prevent the transmission of nociceptive information. However, since all local anesthetics act non-selectively on all types of axons they also cause a loss of innocuous sensation, motor paralysis and autonomic block. Thus, approaches that produce only a selective blockade of pain fibers are of great potential clinical importance. In this chapter we will review the recent findings describing mechanisms of pain transduction and transmission and introduce novel therapeutic approaches to produce pain-selective analgesia.
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Affiliation(s)
- Alexander M Binshtok
- Department of Medical Neurobiology, Institute for Medical Research Israel Canada and Center for Research on Pain, The Hebrew University Medical School, Jerusalem, Israel
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Abstract
The founding member of the TRPP family, TRPP2, was identified as one of the disease genes causing autosomal dominant polycystic kidney disease (ADPKD). ADPKD is the most prevalent, potentially lethal, monogenic disorder in humans, with an average incidence of one in 400 to one in 1,000 individuals worldwide. Here we give an overview of TRPP ion channels and Polycystin-1 receptor proteins focusing on more recent studies. We include the Polycystin-1 family since these proteins are functionally linked to TRPP channels.
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Functional and structural studies of TRP channels heterologously expressed in budding yeast. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011; 704:25-40. [PMID: 21290288 DOI: 10.1007/978-94-007-0265-3_2] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The transient receptor potential (TRP) superfamily is one of the largest families of cation channels. The metazoan TRP family has been subdivided into major branches: TRPC, TRPA, TRPM, TRPP, TRPV, TRPML, and TRPN, while the TRPY family is found in fungi. They are involved in many physiological processes and in the pathogenesis of various disorders. An efficient high-yield expression system for TRP channels is a necessary step towards biophysical and biochemical characterization and structural analysis of these proteins, and the budding yeast, Saccharomyces cerevisiae has proven to be very useful for this purpose. In addition, genetic screens in this organism can be carried out rapidly to identify amino acid residues important for function and to generate useful mutants. Here we present an overview of current developments towards understanding TRP channel function and structure using Saccharomyces cerevisiae as an expression system. In addition, we will summarize recent progress in understanding gating mechanisms of TRP channels using endogenously expressing TRPY channels in S. cerevisiae, and insights gained from genetic screens for mutants in mammalian channels. The discussion will focus particular attention of the use of cryo-electron microscopy (cryo-EM) to determine TRP channel structure, and outlines a "divide and concur" methodology for combining high resolution structures of TRP channel domains determined by X-ray crystallography with lower resolution techniques including cryo-EM and spectroscopy.
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Abstract
Structural studies on TRP channels, while limited, are poised for a quickened pace and rapid expansion. As of yet, no high-resolution structure of a full length TRP channel exists, but low-resolution electron cryomicroscopy structures have been obtained for 4 TRP channels, and high-resolution NMR and X-ray crystal structures have been obtained for the cytoplasmic domains, including an atypical protein kinase domain, ankyrin repeats, coiled coil domains and a Ca(2+)-binding domain, of 6 TRP channels. These structures enhance our understanding of TRP channel assembly and regulation. Continued technical advances in structural approaches promise a bright outlook for TRP channel structural biology.
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Heteromerization of TRP channel subunits: extending functional diversity. Protein Cell 2010; 1:802-10. [PMID: 21203922 DOI: 10.1007/s13238-010-0108-9] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2010] [Accepted: 09/01/2010] [Indexed: 01/03/2023] Open
Abstract
Transient receptor potential (TRP) channels are widely found throughout the animal kingdom. By serving as cellular sensors for a wide spectrum of physical and chemical stimuli, they play crucial physiological roles ranging from sensory transduction to cell cycle modulation. TRP channels are tetrameric protein complexes. While most TRP subunits can form functional homomeric channels, heteromerization of TRP channel subunits of either the same subfamily or different subfamilies has been widely observed. Heteromeric TRP channels exhibit many novel properties compared to their homomeric counterparts, indicating that co-assembly of TRP channel subunits has an important contribution to the diversity of TRP channel functions.
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Holakovska B, Grycova L, Bily J, Teisinger J. Characterization of calmodulin binding domains in TRPV2 and TRPV5 C-tails. Amino Acids 2010; 40:741-8. [PMID: 20686800 DOI: 10.1007/s00726-010-0712-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2010] [Accepted: 07/20/2010] [Indexed: 11/30/2022]
Abstract
The transient receptor potential channels TRPV2 and TRPV5 belong to the vanilloid TRP subfamily. TRPV2 is highly similar to TRPV1 and shares many common properties with it. TRPV5 (and also its homolog TRPV6) is a rather distinct member of the TRPV subfamily. It is distant for being strictly Ca(2+)-selective and features quite different properties from the rest of the TRPV subfamily. It is known that TRP channels are regulated by calmodulin in a calcium-dependent manner. In our study we identified a calmodulin binding site on the C-termini of TRPV2 (654-683) and TRPV5 (587-616) corresponding to the consensus CaM binding motif 1-5-10. The R679 and K681 single mutants of TRPV2 caused a 50% decrease in binding affinity and a double mutation of K661/K664 of the same peptide lowered the binding affinity by up to 75%. A double mutation of R606/K607 and triple mutation of R594/R606/R610 in TRPV5 C-terminal peptide resulted in the total loss of binding affinity to calmodulin. These results demonstrate that the TRPV2 C-tail and TRPV5 C-tail contain calmodulin binding sites and that the basic residues are strongly involved in TRP channel binding to calmodulin.
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Affiliation(s)
- Blanka Holakovska
- Department of Protein Structures, Institute of Physiology, Academy of Sciences of the Czech Republic, Videnska 1083, 142 20, Prague, Czech Republic
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Schumacher MA, Eilers H. TRPV1 splice variants: structure and function. Front Biosci (Landmark Ed) 2010; 15:872-82. [PMID: 20515731 DOI: 10.2741/3651] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The capsaicin receptor (TRPV1) is a non-selective cation channel predominantly expressed in specialized sensory neurons that detect painful stimuli. Although its many functional roles continue to be revealed, it has been confirmed to play a critical role in the perception of peripheral inflammatory hyperalgesia and pain. TRPV1 not only is sensitized and/or activated under a wide range of conditions including inflammation and nerve injury but also undergoes changes in expressed levels in response to these same pathologic conditions. Just as our understanding of the structural requirements of TRPV1 activation has grown, there is evidence that TRPV1 forms heteromeric channel complexes. This review is focused on the structural and functional consequence of TRPV1 splice variants: VR.5'sv, TRPV1b/beta and TRPV1var. Through their co-expression and formation of heteromeric complexes with TRPV1, they have been shown to modulate TRPV1 activation. Moreover, TRPV1 splice variant subunits may also contribute unique properties of activation such as the detection of hypertonic conditions.
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Affiliation(s)
- Mark A Schumacher
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, CA 94143-0427, USA.
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