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Bartók Á, Csanády L. TRPM2 - An adjustable thermostat. Cell Calcium 2024; 118:102850. [PMID: 38237549 DOI: 10.1016/j.ceca.2024.102850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 01/10/2024] [Accepted: 01/10/2024] [Indexed: 02/27/2024]
Abstract
The Transient Receptor Potential Melastatin 2 (TRPM2) channel is a homotetrameric ligand-gated cation channel opened by the binding of cytosolic ADP ribose (ADPR) and Ca2+. In addition, strong temperature dependence of its activity has lately become a center of attention for both physiological and biophysical studies. TRPM2 temperature sensitivity has been affirmed to play a role in central and peripheral thermosensation, pancreatic insulin secretion, and immune cell function. On the other hand, a number of different underlying mechanisms have been proposed from studies in intact cells. This review summarizes available information on TRPM2 temperature sensitivity, with a focus on recent mechanistic insight obtained in a cell-free system. Those biophysical results outline TRPM2 as a channel with an intrinsically endothermic opening transition, a temperature threshold strongly modulated by cytosolic agonist concentrations, and a response steepness greatly enhanced through a positive feedback loop generated by Ca2+ influx through the channel's pore. Complex observations in intact cells and apparent discrepancies between studies using in vivo and in vitro models are discussed and interpreted in light of the intrinsic biophysical properties of the channel protein.
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Affiliation(s)
- Ádám Bartók
- Department of Biochemistry, Semmelweis University, Budapest, Hungary; HCEMM-SE Molecular Channelopathies Research Group, Budapest, Hungary; HUN-REN-SE Ion Channel Research Group, Budapest, Hungary
| | - László Csanády
- Department of Biochemistry, Semmelweis University, Budapest, Hungary; HCEMM-SE Molecular Channelopathies Research Group, Budapest, Hungary; HUN-REN-SE Ion Channel Research Group, Budapest, Hungary.
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2
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Yeh F, Jara-Oseguera A, Aldrich RW. Implications of a temperature-dependent heat capacity for temperature-gated ion channels. Proc Natl Acad Sci U S A 2023; 120:e2301528120. [PMID: 37279277 PMCID: PMC10268252 DOI: 10.1073/pnas.2301528120] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2023] [Accepted: 04/26/2023] [Indexed: 06/08/2023] Open
Abstract
Temperature influences dynamics and state-equilibrium distributions in all molecular processes, and only a relatively narrow range of temperatures is compatible with life-organisms must avoid temperature extremes that can cause physical damage or metabolic disruption. Animals evolved a set of sensory ion channels, many of them in the family of transient receptor potential cation channels that detect biologically relevant changes in temperature with remarkable sensitivity. Depending on the specific ion channel, heating or cooling elicits conformational changes in the channel to enable the flow of cations into sensory neurons, giving rise to electrical signaling and sensory perception. The molecular mechanisms responsible for the heightened temperature-sensitivity in these ion channels, as well as the molecular adaptations that make each channel specifically heat- or cold-activated, are largely unknown. It has been hypothesized that a heat capacity difference (ΔCp) between two conformational states of these biological thermosensors can drive their temperature-sensitivity, but no experimental measurements of ΔCp have been achieved for these channel proteins. Contrary to the general assumption that the ΔCp is constant, measurements from soluble proteins indicate that the ΔCp is likely to be a function of temperature. By investigating the theoretical consequences for a linearly temperature-dependent ΔCp on the open-closed equilibrium of an ion channel, we uncover a range of possible channel behaviors that are consistent with experimental measurements of channel activity and that extend beyond what had been generally assumed to be possible for a simple two-state model, challenging long-held assumptions about ion channel gating models at equilibrium.
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Affiliation(s)
- Frank Yeh
- Institute for Neuroscience, University of Texas at Austin, Austin, TX78712
- Department of Neuroscience, University of Texas at Austin, Austin, TX78712
| | - Andrés Jara-Oseguera
- Institute for Neuroscience, University of Texas at Austin, Austin, TX78712
- Department of Neuroscience, University of Texas at Austin, Austin, TX78712
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX78712
| | - Richard W. Aldrich
- Institute for Neuroscience, University of Texas at Austin, Austin, TX78712
- Department of Neuroscience, University of Texas at Austin, Austin, TX78712
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3
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Rosenbaum T, Morales-Lázaro SL, Islas LD. TRP channels: a journey towards a molecular understanding of pain. Nat Rev Neurosci 2022; 23:596-610. [PMID: 35831443 DOI: 10.1038/s41583-022-00611-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/08/2022] [Indexed: 12/18/2022]
Abstract
The perception of nociceptive signals, which are translated into pain, plays a fundamental role in the survival of organisms. Because pain is linked to a negative sensation, animals learn to avoid noxious signals. These signals are detected by receptors, which include some members of the transient receptor potential (TRP) family of ion channels that act as transducers of exogenous and endogenous noxious cues. These proteins have been in the focus of the field of physiology for several years, and much knowledge of how they regulate the function of the cell types and organs where they are expressed has been acquired. The last decade has been especially exciting because the 'resolution revolution' has allowed us to learn the molecular intimacies of TRP channels using cryogenic electron microscopy. These findings, in combination with functional studies, have provided insights into the role played by these channels in the generation and maintenance of pain.
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Affiliation(s)
- Tamara Rosenbaum
- Departamento de Neurociencia Cognitiva, Instituto de Fisiología Celular, UNAM, Mexico City, Mexico.
| | - Sara L Morales-Lázaro
- Departamento de Neurociencia Cognitiva, Instituto de Fisiología Celular, UNAM, Mexico City, Mexico
| | - León D Islas
- Departamento de Fisiología, Facultad de Medicina, UNAM, Mexico City, Mexico
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Inferiority complex: why do sensory ion channels multimerize? Biochem Soc Trans 2022; 50:213-222. [PMID: 35166323 PMCID: PMC9022975 DOI: 10.1042/bst20211002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 01/19/2022] [Accepted: 01/20/2022] [Indexed: 11/17/2022]
Abstract
Peripheral somatosensory nerves are equipped with versatile molecular sensors which respond to acute changes in the physical environment. Most of these sensors are ion channels that, when activated, depolarize the sensory nerve terminal causing it to generate action potentials, which is the first step in generation of most somatic sensations, including pain. The activation and inactivation of sensory ion channels is tightly regulated and modulated by a variety of mechanisms. Amongst such mechanisms is the regulation of sensory ion channel activity via direct molecular interactions with other proteins in multi-protein complexes at the plasma membrane of sensory nerve terminals. In this brief review, we will consider several examples of such complexes formed around a prototypic sensory receptor, transient receptor potential vanilloid type 1 (TRPV1). We will also discuss some inherent conceptual difficulties arising from the multitude of reported complexes.
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Luu DD, Owens AM, Mebrat MD, Van Horn WD. A molecular perspective on identifying TRPV1 thermosensitive regions and disentangling polymodal activation. Temperature (Austin) 2021; 10:67-101. [PMID: 37187836 PMCID: PMC10177694 DOI: 10.1080/23328940.2021.1983354] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2020] [Revised: 09/10/2021] [Accepted: 09/16/2021] [Indexed: 10/20/2022] Open
Abstract
TRPV1 is a polymodal receptor ion channel that is best known to function as a molecular thermometer. It is activated in diverse ways, including by heat, protons (low pH), and vanilloid compounds, such as capsaicin. In this review, we summarize molecular studies of TRPV1 thermosensing, focusing on the cross-talk between heat and other activation modes. Additional insights from TRPV1 isoforms and non-rodent/non-human TRPV1 ortholog studies are also discussed in this context. While the molecular mechanism of heat activation is still emerging, it is clear that TRPV1 thermosensing is modulated allosterically, i.e., at a distance, with contributions from many distinct regions of the channel. Similarly, current studies identify cross-talk between heat and other TRPV1 activation modes, such as protons and capsaicin, and that these modes can generally be selectively disentangled. In aggregate, this suggests that future TRPV1 molecular studies should define allosteric pathways and provide mechanistic insight, thereby enabling mode-selective manipulation of the polymodal receptor. These advances are anticipated to have significant implications in both basic and applied biomedical sciences.
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Affiliation(s)
- Dustin D. Luu
- School of Molecular Sciences, Arizona State University, Tempe, Arizona, USA
- The Biodesign Institute Virginia G. Piper Center for Personalized Diagnostics,Arizona State University, Tempe, Arizona,USA
| | - Aerial M. Owens
- School of Molecular Sciences, Arizona State University, Tempe, Arizona, USA
- The Biodesign Institute Virginia G. Piper Center for Personalized Diagnostics,Arizona State University, Tempe, Arizona,USA
| | - Mubark D. Mebrat
- School of Molecular Sciences, Arizona State University, Tempe, Arizona, USA
- The Biodesign Institute Virginia G. Piper Center for Personalized Diagnostics,Arizona State University, Tempe, Arizona,USA
| | - Wade D. Van Horn
- School of Molecular Sciences, Arizona State University, Tempe, Arizona, USA
- The Biodesign Institute Virginia G. Piper Center for Personalized Diagnostics,Arizona State University, Tempe, Arizona,USA
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Kamm GB, Boffi JC, Zuza K, Nencini S, Campos J, Schrenk-Siemens K, Sonntag I, Kabaoğlu B, El Hay MYA, Schwarz Y, Tappe-Theodor A, Bruns D, Acuna C, Kuner T, Siemens J. A synaptic temperature sensor for body cooling. Neuron 2021; 109:3283-3297.e11. [PMID: 34672983 DOI: 10.1016/j.neuron.2021.10.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 08/01/2021] [Accepted: 09/30/2021] [Indexed: 10/20/2022]
Abstract
Deep brain temperature detection by hypothalamic warm-sensitive neurons (WSNs) has been proposed to provide feedback information relevant for thermoregulation. WSNs increase their action potential firing rates upon warming, a property that has been presumed to rely on the composition of thermosensitive ion channels within WSNs. Here, we describe a synaptic mechanism that regulates temperature sensitivity of preoptic WSNs and body temperature. Experimentally induced warming of the mouse hypothalamic preoptic area in vivo triggers body cooling. TRPM2 ion channels facilitate this homeostatic response and, at the cellular level, enhance temperature responses of WSNs, thereby linking WSN function with thermoregulation for the first time. Rather than acting within WSNs, we-unexpectedly-find TRPM2 to temperature-dependently increase synaptic drive onto WSNs by disinhibition. Our data emphasize a network-based interoceptive paradigm that likely plays a key role in encoding body temperature and that may facilitate integration of diverse inputs into thermoregulatory pathways.
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Affiliation(s)
- Gretel B Kamm
- Department of Pharmacology, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
| | - Juan C Boffi
- Department of Pharmacology, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany; Department of Functional Neuroanatomy, Institute for Anatomy and Cell Biology, University of Heidelberg, Im Neuenheimer Feld 307, 69120 Heidelberg, Germany
| | - Kristina Zuza
- Department of Pharmacology, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
| | - Sara Nencini
- Department of Pharmacology, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
| | - Joaquin Campos
- Chica and Heinz Schaller Foundation, Institute for Anatomy and Cell Biology, University of Heidelberg, Im Neuenheimer Feld 307, 69120 Heidelberg, Germany
| | - Katrin Schrenk-Siemens
- Department of Pharmacology, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
| | - Ivo Sonntag
- Department of Functional Neuroanatomy, Institute for Anatomy and Cell Biology, University of Heidelberg, Im Neuenheimer Feld 307, 69120 Heidelberg, Germany
| | - Burçe Kabaoğlu
- Department of Pharmacology, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
| | - Muad Y Abd El Hay
- Department of Pharmacology, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
| | - Yvonne Schwarz
- Institute for Physiology, Center of Integrative Physiology and Molecular Medicine, Saarland University, Homburg, Germany
| | - Anke Tappe-Theodor
- Department of Pharmacology, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
| | - Dieter Bruns
- Institute for Physiology, Center of Integrative Physiology and Molecular Medicine, Saarland University, Homburg, Germany
| | - Claudio Acuna
- Chica and Heinz Schaller Foundation, Institute for Anatomy and Cell Biology, University of Heidelberg, Im Neuenheimer Feld 307, 69120 Heidelberg, Germany
| | - Thomas Kuner
- Department of Functional Neuroanatomy, Institute for Anatomy and Cell Biology, University of Heidelberg, Im Neuenheimer Feld 307, 69120 Heidelberg, Germany
| | - Jan Siemens
- Department of Pharmacology, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany; Molecular Medicine Partnership Unit (MMPU), European Molecular Biology Laboratory (EMBL), Meyerhofstraße 1, 69117 Heidelberg, Germany.
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Optical Assessment of Nociceptive TRP Channel Function at the Peripheral Nerve Terminal. Int J Mol Sci 2021; 22:ijms22020481. [PMID: 33418928 PMCID: PMC7825137 DOI: 10.3390/ijms22020481] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 01/01/2021] [Accepted: 01/03/2021] [Indexed: 12/13/2022] Open
Abstract
Free nerve endings are key structures in sensory transduction of noxious stimuli. In spite of this, little is known about their functional organization. Transient receptor potential (TRP) channels have emerged as key molecular identities in the sensory transduction of pain-producing stimuli, yet the vast majority of our knowledge about sensory TRP channel function is limited to data obtained from in vitro models which do not necessarily reflect physiological conditions. In recent years, the development of novel optical methods such as genetically encoded calcium indicators and photo-modulation of ion channel activity by pharmacological tools has provided an invaluable opportunity to directly assess nociceptive TRP channel function at the nerve terminal.
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Xiao R, Xu XZS. Temperature Sensation: From Molecular Thermosensors to Neural Circuits and Coding Principles. Annu Rev Physiol 2020; 83:205-230. [PMID: 33085927 DOI: 10.1146/annurev-physiol-031220-095215] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Temperature is a universal cue and regulates many essential processes ranging from enzymatic reactions to species migration. Due to the profound impact of temperature on physiology and behavior, animals and humans have evolved sophisticated mechanisms to detect temperature changes. Studies from animal models, such as mouse, Drosophila, and C. elegans, have revealed many exciting principles of thermosensation. For example, conserved molecular thermosensors, including thermosensitive channels and receptors, act as the initial detectors of temperature changes across taxa. Additionally, thermosensory neurons and circuits in different species appear to adopt similar logic to transduce and process temperature information. Here, we present the current understanding of thermosensation at the molecular and cellular levels. We also discuss the fundamental coding strategies of thermosensation at the circuit level. A thorough understanding of thermosensation not only provides key insights into sensory biology but also builds a foundation for developing better treatments for various sensory disorders.
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Affiliation(s)
- Rui Xiao
- Department of Aging and Geriatric Research, Institute on Aging and Center for Smell and Taste, University of Florida, Gainesville, Florida 32610, USA;
| | - X Z Shawn Xu
- Life Sciences Institute and Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan 48109, USA;
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