101
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Modular thermal sensors in temperature-gated transient receptor potential (TRP) channels. Proc Natl Acad Sci U S A 2011; 108:11109-14. [PMID: 21690353 DOI: 10.1073/pnas.1105196108] [Citation(s) in RCA: 156] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The molecular basis of the thermal sensitivity of temperature-sensitive channels appears to arise from a specific protein domain rather than integration of global thermal effects. Using systematic chimeric analysis, we show that the N-terminal region that connects ankyrin repeats to the first transmembrane segment is crucial for temperature sensing in heat-activated vanilloid receptor channels. Changing this region both transformed temperature-insensitive isoforms into temperature-sensitive channels and significantly perturbed temperature sensing in temperature-sensitive wild-type channels. Swapping other domains such as the transmembrane core, the C terminus, and the rest of the N terminus had little effect on the steepness of temperature dependence. Our results support that thermal transient receptor potential channels contain modular thermal sensors that confer the unprecedentedly strong temperature dependence to these channels.
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102
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Lin Z, Reilly CA, Antemano R, Hughen RW, Marett L, Concepcion GP, Haygood MG, Olivera BM, Light A, Schmidt EW. Nobilamides A-H, long-acting transient receptor potential vanilloid-1 (TRPV1) antagonists from mollusk-associated bacteria. J Med Chem 2011; 54:3746-55. [PMID: 21524089 DOI: 10.1021/jm101621u] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
New compounds nobilamides A-H and related known compounds A-3302-A and A-3302-B were isolated based upon their suppression of capsaicin-induced calcium uptake in a mouse dorsal root ganglion primary cell culture assay. Two of these compounds, nobilamide B and A-3302-A, were shown to be long-acting antagonists of mouse and human TRPV1 channels, abolishing activity for >1 h after removal of drug presumably via a covalent attachment. Other derivatives also inhibited the TRPV1 channel, albeit with low potency, affording a structure-activity profile to support the proposed mechanism of action. While the activities were modest, we propose a new mechanism of action and a new site of binding for these inhibitors that may spur development of related analogues for treatment of pain.
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Affiliation(s)
- Zhenjian Lin
- Department of Medicinal Chemistry, University of Utah , Salt Lake City, UT 84112, USA
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103
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Temperature-dependent STIM1 activation induces Ca²+ influx and modulates gene expression. Nat Chem Biol 2011; 7:351-8. [PMID: 21499266 PMCID: PMC3097298 DOI: 10.1038/nchembio.558] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Accepted: 02/15/2011] [Indexed: 12/11/2022]
Abstract
Intracellular Ca2+ is essential for diverse cellular functions. Ca2+ entry into many cell types including immune cells is triggered by depleting endoplasmic reticulum (ER) Ca2+, a process termed store-operated Ca2+ entry (SOCE). STIM1 is an ER Ca2+ sensor. Upon Ca2+ store depletion, STIM1 clusters at ER-plasma membrane junctions where it interacts with and gates Ca2+-permeable Orai1 ion channels. Here we show that STIM1 is also activated by temperature. Heating cells caused clustering of STIM1 at temperatures above 35°C without depleting Ca2+ stores, and led to STIM1/Orai1-mediated Ca2+ influx as a heat off-response (response after cooling). Interestingly, the functional coupling of STIM1 and Orai1 is prevented at high temperatures, potentially explaining the heat off-response. Importantly, physiologically-relevant temperature shifts modulates STIM1-dependent gene expression in Jurkat T-cells. Therefore, temperature is an important regulator of STIM1 function.
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104
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Saito S, Fukuta N, Shingai R, Tominaga M. Evolution of vertebrate transient receptor potential vanilloid 3 channels: opposite temperature sensitivity between mammals and western clawed frogs. PLoS Genet 2011; 7:e1002041. [PMID: 21490957 PMCID: PMC3072374 DOI: 10.1371/journal.pgen.1002041] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Accepted: 02/16/2011] [Indexed: 01/04/2023] Open
Abstract
Transient Receptor Potential (TRP) channels serve as temperature receptors in a wide variety of animals and must have played crucial roles in thermal adaptation. The TRP vanilloid (TRPV) subfamily contains several temperature receptors with different temperature sensitivities. The TRPV3 channel is known to be highly expressed in skin, where it is activated by warm temperatures and serves as a sensor to detect ambient temperatures near the body temperature of homeothermic animals such as mammals. Here we performed comprehensive comparative analyses of the TRPV subfamily in order to understand the evolutionary process; we identified novel TRPV genes and also characterized the evolutionary flexibility of TRPV3 during vertebrate evolution. We cloned the TRPV3 channel from the western clawed frog Xenopus tropicalis to understand the functional evolution of the TRPV3 channel. The amino acid sequences of the N- and C-terminal regions of the TRPV3 channel were highly diversified from those of other terrestrial vertebrate TRPV3 channels, although central portions were well conserved. In a heterologous expression system, several mammalian TRPV3 agonists did not activate the TRPV3 channel of the western clawed frog. Moreover, the frog TRPV3 channel did not respond to heat stimuli, instead it was activated by cold temperatures. Temperature thresholds for activation were about 16 °C, slightly below the lower temperature limit for the western clawed frog. Given that the TRPV3 channel is expressed in skin, its likely role is to detect noxious cold temperatures. Thus, the western clawed frog and mammals acquired opposite temperature sensitivity of the TRPV3 channel in order to detect environmental temperatures suitable for their respective species, indicating that temperature receptors can dynamically change properties to adapt to different thermal environments during evolution. Evolution of temperature perception is crucial for adaptation to thermal environments; however, this process is poorly understood. Here we investigated the evolution of the vertebrate TRPV subfamily which contains several mammalian temperature receptors. We identified several novel TRPV genes that have not been found previously and discovered evolutionary flexibility of the TRPV3 gene during vertebrate evolution. TRPV3 channels perceive warm temperature and serve as sensors to detect ambient temperatures near the body temperature of homeothermic animals such as mammals. To examine the functional evolution of TRPV3 channels in vertebrate evolution, we cloned the gene from the western clawed frog and found that its N- and C-terminal regions were highly diversified from those of other terrestrial vertebrate TRPV3 channels. Characterization of the channel properties of western clawed frog TRPV3 revealed that it was not activated by heat stimuli, but instead was activated by cold stimuli. Temperature thresholds for activation were about 16 °C, slightly below the lower temperature limit for the western clawed frog. Thus, the western clawed frog and mammals acquired opposite temperature sensitivity of TRPV3 channels to detect environmental temperatures suitable for their respective species, indicating that temperature receptors can dynamically change properties to adapt to thermal environments during evolution.
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Affiliation(s)
- Shigeru Saito
- Division of Cell Signaling, Okazaki Institute for Integrative Bioscience (National Institute for Physiological Sciences), National Institutes of Natural Sciences, Okazaki, Aichi, Japan
- * E-mail: (SS); (MT)
| | - Naomi Fukuta
- Division of Cell Signaling, Okazaki Institute for Integrative Bioscience (National Institute for Physiological Sciences), National Institutes of Natural Sciences, Okazaki, Aichi, Japan
| | - Ryuzo Shingai
- Laboratory of Bioscience, Faculty of Engineering, Iwate University, Morioka, Iwate, Japan
| | - Makoto Tominaga
- Division of Cell Signaling, Okazaki Institute for Integrative Bioscience (National Institute for Physiological Sciences), National Institutes of Natural Sciences, Okazaki, Aichi, Japan
- Department of Physiological Sciences, The Graduate University for Advanced Studies, Okazaki, Aichi, Japan
- * E-mail: (SS); (MT)
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105
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Doerner JF, Hatt H, Ramsey IS. Voltage- and temperature-dependent activation of TRPV3 channels is potentiated by receptor-mediated PI(4,5)P2 hydrolysis. ACTA ACUST UNITED AC 2011; 137:271-88. [PMID: 21321070 PMCID: PMC3047606 DOI: 10.1085/jgp.200910388] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
TRPV3 is a thermosensitive channel that is robustly expressed in skin keratinocytes and activated by innocuous thermal heating, membrane depolarization, and chemical agonists such as 2-aminoethyoxy diphenylborinate, carvacrol, and camphor. TRPV3 modulates sensory thermotransduction, hair growth, and susceptibility to dermatitis in rodents, but the molecular mechanisms responsible for controlling TRPV3 channel activity in keratinocytes remain elusive. We show here that receptor-mediated breakdown of the membrane lipid phosphatidylinositol (4,5) bisphosphate (PI(4,5)P2) regulates the activity of both native TRPV3 channels in primary human skin keratinocytes and expressed TRPV3 in a HEK-293–derived cell line stably expressing muscarinic M1-type acetylcholine receptors. Stimulation of PI(4,5)P2 hydrolysis or pharmacological inhibition of PI 4 kinase to block PI(4,5)P2 synthesis potentiates TRPV3 currents by causing a negative shift in the voltage dependence of channel opening, increasing the proportion of voltage-independent current and causing thermal activation to occur at cooler temperatures. The activity of single TRPV3 channels in excised patches is potentiated by PI(4,5)P2 depletion and selectively decreased by PI(4,5)P2 compared with related phosphatidylinositol phosphates. Neutralizing mutations of basic residues in the TRP domain abrogate the effect of PI(4,5)P2 on channel function, suggesting that PI(4,5)P2 directly interacts with a specific protein motif to reduce TRPV3 channel open probability. PI(4,5)P2-dependent modulation of TRPV3 activity represents an attractive mechanism for acute regulation of keratinocyte signaling cascades that control cell proliferation and the release of autocrine and paracrine factors.
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Affiliation(s)
- Julia F Doerner
- Department of Cell Physiology, Ruhr University Bochum, 44801 Bochum, Germany
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106
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The C-terminal basic residues contribute to the chemical- and voltage-dependent activation of TRPA1. Biochem J 2011; 433:197-204. [PMID: 20946100 PMCID: PMC3010083 DOI: 10.1042/bj20101256] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The ankyrin transient receptor potential channel TRPA1 is a non-selective
cationic channel that is expressed by sensory neurons, where it can be activated
by pungent chemicals, such as AITC (allyl isothiocyanate), cinnamon or allicin,
by deep cooling (<18 °C) or highly depolarizing
voltages (>+100 mV). From the cytoplasmic side, this channel can be
regulated by negatively charged ligands such as phosphoinositides or inorganic
polyphosphates, most likely through an interaction with as yet unidentified
positively charged domain(s). In the present study, we mutated 27 basic residues
along the C-terminal tail of TRPA1, trying to explore their role in AITC- and
voltage-dependent gating. In the proximal part of the C-terminus, the
function-affecting mutations were at Lys969, Arg975,
Lys988 and Lys989. A second significant region was
found in the predicted helix, centred around Lys1048 and
Lys1052, in which single alanine mutations completely abolished AITC-
and voltage-dependent activation. In the distal portion of the C-terminus, the
charge neutralizations K1092A and R1099A reduced the AITC sensitivity, and, in
the latter mutant, increased the voltage-induced steady-state responses. Taken
together, our findings identify basic residues in the C-terminus that are
strongly involved in TRPA1 voltage and chemical sensitivity, and some of them
may represent possible interaction sites for negatively charged molecules that
are generally considered to modulate TRPA1.
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107
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Aneiros E, Cao L, Papakosta M, Stevens EB, Phillips S, Grimm C. The biophysical and molecular basis of TRPV1 proton gating. EMBO J 2011; 30:994-1002. [PMID: 21285946 DOI: 10.1038/emboj.2011.19] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2010] [Accepted: 01/07/2011] [Indexed: 11/09/2022] Open
Abstract
The capsaicin receptor TRPV1, a member of the transient receptor potential family of non-selective cation channels is a polymodal nociceptor. Noxious thermal stimuli, protons, and the alkaloid irritant capsaicin open the channel. The mechanisms of heat and capsaicin activation have been linked to voltage-dependent gating in TRPV1. However, until now it was unclear whether proton activation or potentiation or both are linked to a similar voltage-dependent mechanism and which molecular determinants underlie the proton gating. Using the whole-cell patch-clamp technique, we show that protons activate and potentiate TRPV1 by shifting the voltage dependence of the activation curves towards more physiological membrane potentials. We further identified a key residue within the pore region of TRPV1, F660, to be critical for voltage-dependent proton activation and potentiation. We conclude that proton activation and potentiation of TRPV1 are both voltage dependent and that amino acid 660 is essential for proton-mediated gating of TRPV1.
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Affiliation(s)
- Eduardo Aneiros
- Department of Pain Biology, Pfizer Global Research and Development, Sandwich Laboratories, Kent, UK
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108
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Yao J, Liu B, Qin F. Kinetic and energetic analysis of thermally activated TRPV1 channels. Biophys J 2011; 99:1743-53. [PMID: 20858418 DOI: 10.1016/j.bpj.2010.07.022] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2010] [Revised: 06/25/2010] [Accepted: 07/02/2010] [Indexed: 12/27/2022] Open
Abstract
Thermal TRP channels are important for thermal sensation and nociception, but their gating mechanisms have remained elusive. With optically generated submillisecond temperature steps from 22°C to >60°C, we have directly measured the activation and deactivation kinetics of TRPV1 channels, and from the measurements we determined the energetics of thermal gating. We show that activation by temperature follows single exponential time courses. It occurs in a few milliseconds and is significantly faster than activation by agonists. The gating has characteristics of a melting process involving large compensatory enthalpy (>100 kcal/mol) and entropy changes with little free energy change. The reaction path is asymmetrical with temperature mainly driving the opening while the closing has nominal but negative temperature dependence (i.e., sensitivity to cold). Both voltage and agonists alter the slope of the temperature-dependent gating curve as well as shifting the midpoint. However, compared to the energetic effect of temperature on gating, the effect of voltage is small. Our data on the interdependence between voltage and direct temperature responses are not fit to a model involving independent stimuli but instead support a temperature-sensing mechanism that is coupled to charge movement or agonist binding.
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Affiliation(s)
- Jing Yao
- Department of Physiology and Biophysical Sciences, State University of New York, Buffalo, New York, USA
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109
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Brauchi S, Orio P. Voltage sensing in thermo-TRP channels. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011; 704:517-30. [PMID: 21290314 DOI: 10.1007/978-94-007-0265-3_28] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Membrane voltage, ligand binding, mechanical force and temperature can all induce conformational changes that open ion channel pores. A key question in understanding ion channel function is how the protein domains involved in sensing stimuli (sensors) communicate with the pore to gate its opening and closing. TRP channels are considered six-transmembrane cation-permeable channels, distant relatives of voltage-gated potassium channels (Kv), which are known to be activated by membrane depolarization. Understanding the molecular nature of thermo-TRP channel gating offers a fair challenge to biophysicists. This chapter will summarize our present knowledge on the effect of voltage and temperature during thermo-TRP channel activation.
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Affiliation(s)
- Sebastian Brauchi
- Facultad de Medicina, Instituto de Fisiologia, Universidad Austral de Chile, Valdivia 511-0566, Chile.
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110
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Thermo-TRP channels: biophysics of polymodal receptors. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011; 704:469-90. [PMID: 21290312 DOI: 10.1007/978-94-007-0265-3_26] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
In this chapter we discuss the polymodal activation of thermo-TRP channels using as exemplars two of the best characterized members of this class of channels: TRPM8 and TRPV1. Since channel activation by temperature is the hallmark of thermo-TRP channels, we present a detailed discussion on the thermodynamics involved in the gating processes by temperature, voltage, and agonists. We also review recently published data in an effort to put together all the pieces available of the amazing puzzle of thermo-TRP channel activation. Special emphasis is made in the structural components that allow the channel-forming proteins to integrate such diverse stimuli, and in the coupling between the different sensors and the ion conduction pathway. We conclude that the present data is most economically explained by allosteric models in which temperature, voltage, and agonists act separately to modulate channel activity.
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111
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Boukalova S, Marsakova L, Teisinger J, Vlachova V. Conserved residues within the putative S4-S5 region serve distinct functions among thermosensitive vanilloid transient receptor potential (TRPV) channels. J Biol Chem 2010; 285:41455-62. [PMID: 21044960 DOI: 10.1074/jbc.m110.145466] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The vanilloid transient receptor potential channel TRPV1 is a tetrameric six-transmembrane segment (S1-S6) channel that can be synergistically activated by various proalgesic agents such as capsaicin, protons, heat, or highly depolarizing voltages, and also by 2-aminoethoxydiphenyl borate (2-APB), a common activator of the related thermally gated vanilloid TRP channels TRPV1, TRPV2, and TRPV3. In these channels, the conserved charged residues in the intracellular S4-S5 region have been proposed to constitute part of a voltage sensor that acts in concert with other stimuli to regulate channel activation. The molecular basis of this gating event is poorly understood. We mutated charged residues all along the S4 and the S4-S5 linker of TRPV1 and identified four potential voltage-sensing residues (Arg(557), Glu(570), Asp(576), and Arg(579)) that, when specifically mutated, altered the functionality of the channel with respect to voltage, capsaicin, heat, 2-APB, and/or their interactions in different ways. The nonfunctional charge-reversing mutations R557E and R579E were partially rescued by the charge-swapping mutations R557E/E570R and D576R/R579E, indicating that electrostatic interactions contribute to allosteric coupling between the voltage-, temperature- and capsaicin-dependent activation mechanisms. The mutant K571E was normal in all aspects of TRPV1 activation except for 2-APB, revealing the specific role of Lys(571) in chemical sensitivity. Surprisingly, substitutions at homologous residues in TRPV2 or TRPV3 had no effect on temperature- and 2-APB-induced activity. Thus, the charged residues in S4 and the S4-S5 linker contribute to voltage sensing in TRPV1 and, despite their highly conserved nature, regulate the temperature and chemical gating in the various TRPV channels in different ways.
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Affiliation(s)
- Stepana Boukalova
- Department of Cellular Neurophysiology, Institute of Physiology, Academy of Sciences of the Czech Republic, Videnska 1083, 142 20 Prague 4, Czech Republic
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112
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Yang F, Cui Y, Wang K, Zheng J. Reply to Yao et al.: Is the pore turret just thermoTRP channels’ appendix? Proc Natl Acad Sci U S A 2010; 107. [PMCID: PMC2922588 DOI: 10.1073/pnas.1008504107] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023] Open
Affiliation(s)
- Fan Yang
- Department of Physiology and Membrane Biology, University of California, Davis, CA 95616; and
| | - Yuanyuan Cui
- Department of Physiology and Membrane Biology, University of California, Davis, CA 95616; and
- Department of Neurobiology, Neuroscience Research Institute, Peking UniversityHealth Science Center, Beijing 100083, China
| | - Kewei Wang
- Department of Neurobiology, Neuroscience Research Institute, Peking UniversityHealth Science Center, Beijing 100083, China
| | - Jie Zheng
- Department of Physiology and Membrane Biology, University of California, Davis, CA 95616; and
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113
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Pore turret of thermal TRP channels is not essential for temperature sensing. Proc Natl Acad Sci U S A 2010; 107:E125; author reply E126-7. [PMID: 20660307 DOI: 10.1073/pnas.1008272107] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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114
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A bivalent tarantula toxin activates the capsaicin receptor, TRPV1, by targeting the outer pore domain. Cell 2010; 141:834-45. [PMID: 20510930 DOI: 10.1016/j.cell.2010.03.052] [Citation(s) in RCA: 238] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2009] [Revised: 01/12/2010] [Accepted: 03/30/2010] [Indexed: 11/22/2022]
Abstract
Toxins have evolved to target regions of membrane ion channels that underlie ligand binding, gating, or ion permeation, and have thus served as invaluable tools for probing channel structure and function. Here, we describe a peptide toxin from the Earth Tiger tarantula that selectively and irreversibly activates the capsaicin- and heat-sensitive channel, TRPV1. This high-avidity interaction derives from a unique tandem repeat structure of the toxin that endows it with an antibody-like bivalency. The "double-knot" toxin traps TRPV1 in the open state by interacting with residues in the presumptive pore-forming region of the channel, highlighting the importance of conformational changes in the outer pore region of TRP channels during activation.
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115
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Grandl J, Kim SE, Uzzell V, Bursulaya B, Petrus M, Bandell M, Patapoutian A. Temperature-induced opening of TRPV1 ion channel is stabilized by the pore domain. Nat Neurosci 2010; 13:708-14. [PMID: 20414199 PMCID: PMC2876202 DOI: 10.1038/nn.2552] [Citation(s) in RCA: 160] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2010] [Accepted: 04/15/2010] [Indexed: 02/08/2023]
Abstract
TRPV1 is the founding and best-studied member of the family of temperature-activated transient receptor potential ion channels (thermoTRPs). Voltage, chemicals, and heat amongst other agonists allosterically gate TRPV1. Molecular determinants for TRPV1 activation by capsaicin, allicin, acid, ammonia, and voltage have been identified. However, the structures and mechanisms mediating its pronounced temperature-sensitivity remain unclear. Recent studies of the related channel TRPV3 identified residues within the pore region required for heat activation. Here we use both random and targeted mutagenesis screens of TRPV1 and identify point mutations in the outer pore region that specifically impair temperature-activation. Single channel analysis shows that TRPV1 mutations disrupt heat-sensitivity by ablating long channel openings, that are part of the temperature-gating pathway. We propose that sequential occupancy of short and long open states upon activation provides a mechanism to enhance temperature-sensitivity. Our study suggests that the outer pore plays a general role in heat-sensitivity of thermoTRPs.
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Affiliation(s)
- Jörg Grandl
- Department of Cell Biology, Scripps Research Institute, La Jolla, California, USA
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116
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117
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Thermosensitive TRP channel pore turret is part of the temperature activation pathway. Proc Natl Acad Sci U S A 2010; 107:7083-8. [PMID: 20351268 DOI: 10.1073/pnas.1000357107] [Citation(s) in RCA: 152] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Temperature sensing is crucial for homeotherms, including human beings, to maintain a stable body core temperature and respond to the ambient environment. A group of exquisitely temperature-sensitive transient receptor potential channels, termed thermoTRPs, serve as cellular temperature sensors. How thermoTRPs convert thermal energy (heat) into protein conformational changes leading to channel opening remains unknown. Here we demonstrate that the pathway for temperature-dependent activation is distinct from those for ligand- and voltage-dependent activation and involves the pore turret. We found that mutant channels with an artificial pore turret sequence lose temperature sensitivity but maintain normal ligand responses. Using site-directed fluorescence recordings we observed that temperature change induces a significant rearrangement of TRPV1 pore turret that is coupled to channel opening. This movement is specifically associated to temperature-dependent activation and is not observed during ligand- and voltage-dependent channel activation. These observations suggest that the turret is part of the temperature-sensing apparatus in thermoTRP channels, and its conformational change may give rise to the large entropy that defines high temperature sensitivity.
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118
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Abstract
Although a unifying characteristic common to all transient receptor potential (TRP) channel functions remains elusive, they could be described as tetramers formed by subunits with six transmembrane domains and containing cation-selective pores, which in several cases show high calcium permeability. TRP channels constitute a large superfamily of ion channels, and can be grouped into seven subfamilies based on their amino acid sequence homology: the canonical or classic TRPs, the vanilloid receptor TRPs, the melastatin or long TRPs, ankyrin (whose only member is the transmembrane protein 1 [TRPA1]), TRPN after the nonmechanoreceptor potential C (nonpC), and the more distant cousins, the polycystins and mucolipins. Because of their role as cellular sensors, polymodal activation and gating properties, many TRP channels are activated by a variety of different stimuli and function as signal integrators. Thus, how TRP channels function and how function relates to given structural determinants contained in the channel-forming protein has attracted the attention of biophysicists as well as molecular and cell biologists. The main purpose of this review is to summarize our present knowledge on the structure of channels of the TRP ion channel family. In the absence of crystal structure information for a complete TRP channel, we will describe important protein domains present in TRP channels, structure-function mutagenesis studies, the few crystal structures available for some TRP channel modules, and the recent determination of some TRP channel structures using electron microscopy.
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119
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Phelps CB, Wang RR, Choo SS, Gaudet R. Differential regulation of TRPV1, TRPV3, and TRPV4 sensitivity through a conserved binding site on the ankyrin repeat domain. J Biol Chem 2009; 285:731-40. [PMID: 19864432 DOI: 10.1074/jbc.m109.052548] [Citation(s) in RCA: 133] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Transient receptor potential vanilloid (TRPV) channels, which include the thermosensitive TRPV1-V4, have large cytoplasmic regions flanking the transmembrane domain, including an N-terminal ankyrin repeat domain. We show that a multiligand binding site for ATP and calmodulin previously identified in the TRPV1 ankyrin repeat domain is conserved in TRPV3 and TRPV4, but not TRPV2. Accordingly, TRPV2 is insensitive to intracellular ATP, while, as previously observed with TRPV1, a sensitizing effect of ATP on TRPV4 required an intact binding site. In contrast, ATP reduced TRPV3 sensitivity and potentiation by repeated agonist stimulations. Thus, ATP and calmodulin, acting through this conserved binding site, are key players in generating the different sensitivity and adaptation profiles of TRPV1, TRPV3, and TRPV4. Our results suggest that competing interactions of ATP and calmodulin influence channel sensitivity to fluctuations in calcium concentration and perhaps even metabolic state. Different feedback mechanisms likely arose because of the different physiological stimuli or temperature thresholds of these channels.
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Affiliation(s)
- Christopher B Phelps
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138, USA
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120
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Yao J, Liu B, Qin F. Rapid temperature jump by infrared diode laser irradiation for patch-clamp studies. Biophys J 2009; 96:3611-9. [PMID: 19413966 DOI: 10.1016/j.bpj.2009.02.016] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2009] [Revised: 02/09/2009] [Accepted: 02/11/2009] [Indexed: 10/20/2022] Open
Abstract
Several thermal TRP ion channels have recently been identified. These channels are directly gated by temperature, but the mechanisms have remained elusive. Studies of their temperature gating have been impeded by lack of methods for rapid alteration of temperature in live cells. As a result, only measurements of steady-state properties have been possible. To solve the problem, we have developed an optical approach that uses recently available infrared diode lasers as heat sources. By restricting laser irradiation around a single cell, our approach can produce constant temperature jumps over 50 degrees C in submilliseconds. Experiments with several heat-gated ion channels (TRPV1-3) show its applicability for rapid temperature perturbation in both single cells and membrane patches. Compared with other laser heating approaches such as those by Raman-shifting of the Nd:YAG fundamentals, our approach has the advantage of being cost effective and applicable to live cells while providing an adequate resolution for time-resolved detection of channel activation.
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Affiliation(s)
- Jing Yao
- Department of Physiology and Biophysical Sciences, State University of New York at Buffalo, Buffalo, New York 14214, USA
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121
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Salazar H, Jara-Oseguera A, Hernández-García E, Llorente I, Arias-Olguín II, Soriano-García M, Islas LD, Rosenbaum T. Structural determinants of gating in the TRPV1 channel. Nat Struct Mol Biol 2009; 16:704-10. [PMID: 19561608 DOI: 10.1038/nsmb.1633] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2009] [Accepted: 06/04/2009] [Indexed: 12/23/2022]
Abstract
Transient receptor potential vanilloid 1 (TRPV1) channels mediate several types of physiological responses. Despite the importance of these channels in pain detection and inflammation, little is known about how their structural components convert different types of stimuli into channel activity. To localize the activation gate of these channels, we inserted cysteines along the S6 segment of mutant TRPV1 channels and assessed their accessibility to thiol-modifying agents. We show that access to the pore of TRPV1 is gated by S6 in response to both capsaicin binding and increases in temperature, that the pore-forming S6 segments are helical structures and that two constrictions are present in the pore: one that impedes the access of large molecules and the other that hampers the access of smaller ions and constitutes an activation gate of these channels.
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Affiliation(s)
- Héctor Salazar
- Departamento de Biofísica, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México, D.F., México
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122
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Minor DL. Searching for interesting channels: pairing selection and molecular evolution methods to study ion channel structure and function. MOLECULAR BIOSYSTEMS 2009; 5:802-10. [PMID: 19603113 DOI: 10.1039/b901708a] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The pairing of selection and screening methods with randomly mutated libraries can be an exceptionally powerful means for probing the functions of biological molecules and for developing novel regents from random libraries of peptides and oligonucleotides. The use of such approaches is beginning to permeate the ion channel field where they are being deployed to uncover fundamental aspects about ion channel structure and gating, small molecule-channel interactions, and the development of novel agents to control channel activity.
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Affiliation(s)
- Daniel L Minor
- Department of Biochemistry and Biophysics, Cardiovascular Research Institute, California Institute for Quantitative Biosciences, University of California, San Francisco, CA 94158-2330, USA.
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123
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Aneiros E, Dabrowski M. Novel Temperature Activation Cell-Based Assay on Thermo-TRP Ion Channels. ACTA ACUST UNITED AC 2009; 14:662-7. [DOI: 10.1177/1087057109336595] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The precise temperature control of the ABI Prism® 7900HT Sequence Detection System designed for detection of fluorescence of a biological sample in real-time PCR assays (TaqMan assays) was used to activate Thermo-TRP ion channels, enabling a novel 384-/96-well plate-based assay. Functional pharmacology was verified against the temperature activation using intracellular calcium fluorescence as a measure of ion channel activity. The assay is applicable to both heterologous expression systems and dorsal root ganglia primary cells. This will benefit several analgesic drug discovery programs searching for new Thermo-TRP modulators. ( Journal of Biomolecular Screening 2009:662-667)
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124
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Su Z, Zhou X, Loukin SH, Haynes WJ, Saimi Y, Kung C. The use of yeast to understand TRP-channel mechanosensitivity. Pflugers Arch 2009; 458:861-7. [PMID: 19462180 DOI: 10.1007/s00424-009-0680-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2009] [Accepted: 04/30/2009] [Indexed: 01/04/2023]
Abstract
Mechanosensitive (MS) ion channels likely underlie myriad force-sensing processes, from basic osmotic regulation to specified sensations of animal hearing and touch. Albeit important, the molecular identities of many eukaryotic MS channels remain elusive, let alone their working mechanisms. This is in stark contrast to our advanced knowledge on voltage- or ligand-sensitive channels. Several members of transient receptor potential (TRP) ion channel family have been implicated to function in mechanosensation and are recognized as promising candidate MS channels. The yeast TRP homolog, TRPY1, is clearly a first-line force transducer. It can be activated by hypertonic shock in vivo and by membrane stretch force in excised patches under patch clamp, making it a useful model for understanding TRP channel mechanosensitivity in general. TRPY1 offers two additional research advantages: (1) It has a large ( approximately 300 pS) unitary conductance and therefore a favorable S/N ratio. (2) Budding yeast allows convenient and efficient genetic and molecular manipulations. In this review, we focus on the current research of TRPY1 and discuss its prospect. We also describe the use of yeast as a system to express and characterize animal TRP channels.
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Affiliation(s)
- Zhenwei Su
- Laboratory of Molecular Biology, 305 R.M. Bock Laboratories, 1525 Linden Drive, Madison, WI 53706, USA.
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125
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Bang S, Hwang SW. Polymodal ligand sensitivity of TRPA1 and its modes of interactions. ACTA ACUST UNITED AC 2009; 133:257-62. [PMID: 19237591 PMCID: PMC2654089 DOI: 10.1085/jgp.200810138] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Sangsu Bang
- Korea University Graduate School of Medicine, Seoul 136-705, Korea
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126
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Benedikt J, Samad A, Ettrich R, Teisinger J, Vlachova V. Essential role for the putative S6 inner pore region in the activation gating of the human TRPA1 channel. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2009; 1793:1279-88. [PMID: 19422860 DOI: 10.1016/j.bbamcr.2009.04.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 01/05/2009] [Revised: 04/06/2009] [Accepted: 04/27/2009] [Indexed: 11/28/2022]
Abstract
The ankyrin transient receptor potential channel TRPA1 is a sensory neuron-specific channel that is gated by various proalgesic agents such as allyl isothiocyanate (AITC), deep cooling or highly depolarizing voltages. How these disparate stimuli converge on the channel protein to open/close its ion-conducting pore is unknown. We identify several residues within the S6 inner pore-forming region of human TRPA1 that contribute to AITC and voltage-dependent gating. Alanine substitution in the conserved mid-S6 proline (P949A) strongly affected the activation/deactivation and ion permeation. The P949A was functionally restored by substitution with a glycine but not by the introduction of a proline at positions -1, -2 or +1, which indicates that P949 is structurally required for the normal functioning of the TRPA1 channel. Mutation N954A generated a constitutively open phenotype, suggesting a role in stabilizing the closed conformation. Alanine substitutions in the distal GXXXG motif decreased the relative permeability of the channel for Ca(2+) and strongly affected its activation/deactivation properties, indicating that the distal G962 stabilizes the open conformation. G958, on the other hand, provides additional tuning leading to decreased channel activity. Together these findings provide functional support for the critical role of the putative inner pore region in controlling the conformational changes that determine the transitions between the open and close states of the TRPA1 channel.
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Affiliation(s)
- Jan Benedikt
- Department of Cellular Neurophysiology, Institute of Physiology, Academy of Sciences of the Czech Republic, Videnska 1083, 142 20 Prague 4, Czech Republic
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127
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Su Z, Zhou X, Loukin SH, Saimi Y, Kung C. Mechanical force and cytoplasmic Ca(2+) activate yeast TRPY1 in parallel. J Membr Biol 2009; 227:141-50. [PMID: 19219385 DOI: 10.1007/s00232-009-9153-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2008] [Accepted: 01/16/2009] [Indexed: 01/13/2023]
Abstract
The ability to sense mechanical and osmotic stimuli is vital to all organisms from mammals to bacteria. Members of the transient receptor potential (TRP) ion-channel family have attracted intense attention for their involvement in mechanosensation. The yeast homologue TRPY1 can clearly be activated by hypertonic shock in vivo and by stretch force under patch clamp. Like its animal counterparts, TRPY1 is polymodal, being gated by membrane stretch force and by cytoplasmic Ca(2+). Here, we investigated how these two gating principles interact. We found that stretch force can induce some channel activation without cytoplasmic Ca(2+). Tens of micromolar Ca(2+) greatly enhance the observed force-induced activities, with open probabilities following well the Boltzmann distribution, in which the two gating energies are summed as exponents. To map this formalism to structures, we found Ca(2+)-binding proteins such as calmodulin or calcineurin to be unnecessary. However, removing a dense cluster of negative charges in the C-terminal cytoplasmic domain of TRPY1 greatly diminishes the Ca(2+) activation as well as its influence on force activation. We also found a strategic point upstream of this charge cluster, at which insertion of amino acids weakens Ca(2+) activation considerably but leaves the mechanosensitivity nearly intact. These results led to a structure-function model in which Ca(2+) binding to the cytoplasmic domain and stretching of the membrane-embedded domain both generate gating force, reaching the gate in parallel.
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Affiliation(s)
- Zhenwei Su
- University of Wisconsin-Madison, 53706, USA
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128
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Myers BR, Saimi Y, Julius D, Kung C. Multiple unbiased prospective screens identify TRP channels and their conserved gating elements. ACTA ACUST UNITED AC 2009; 132:481-6. [PMID: 18955590 PMCID: PMC2571970 DOI: 10.1085/jgp.200810104] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Benjamin R Myers
- Department of Physiology, University of California, San Francisco, CA 94143, USA
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129
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Two amino acid residues determine 2-APB sensitivity of the ion channels TRPV3 and TRPV4. Proc Natl Acad Sci U S A 2009; 106:1626-31. [PMID: 19164517 DOI: 10.1073/pnas.0812209106] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Temperature-activated transient receptor potential ion channels (thermoTRPs) are polymodal detectors of various stimuli including temperature, voltage, and chemicals. To date, it is not known how TRP channels integrate the action of such disparate stimuli. Identifying specific residues required for channel-activation by distinct stimuli is necessary for understanding overall TRP channel function. TRPV3 is activated by warm temperatures and various chemicals, and is modulated by voltage. One potent activator of TRPV3 is 2-aminoethyl diphenylborinate (2-APB), a synthetic chemical that modulates many TRP channels. In a high-throughput mutagenesis screen of approximately 14,000 mutated mouse TRPV3 clones, we found 2 residues (H426 and R696) specifically required for sensitivity of TRPV3 to 2-APB, but not to camphor or voltage. The cytoplasmic N-terminal mutation H426N in human, dog, and frog TRPV3 also effectively abolished 2-APB activation without affecting camphor responses. Interestingly, chicken TRPV3 is weakly sensitive to 2-APB, and the equivalent residue at 426 is an asparagine (N). Mutating this residue to histidine induced 2-APB sensitivity of chicken TRPV3 to levels comparable for other TRPV3 orthologs. The cytoplasmic C-terminal mutation R696K in the TRP box displayed 2-APB specific deficits only in the presence of extracellular calcium, suggesting involvement in gating. TRPV4, a related thermoTRP, is 2-APB insensitive and has variant sequences at both residues identified here. Remarkably, mutating these 2 residues in TRPV4 to TRPV3 sequences (N426H and W737R) was sufficient to induce TRPV3-like 2-APB sensitivity. Therefore, 2-APB activation of TRPV3 is separable from other activation mechanisms, and depends on 2 cytoplasmic residues.
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