scholarly journals Emerging Role of Transient Receptor Potential Vanilloid 4 (TRPV4) Ion Channel in Acute and Chronic Itch

2021 ◽  
Vol 22 (14) ◽  
pp. 7591
Author(s):  
Qiaojuan Zhang ◽  
Gwendolyn Henry ◽  
Yong Chen

Itch is a clinical problem that leaves many sufferers insufficiently treated, with over 20 million cases in the United States. This is due to incomplete understanding of its molecular, cellular, and cell-to-cell signaling mechanisms. Transient receptor potential (TRP) ion channels are involved in several sensory modalities including pain, vision, taste, olfaction, hearing, touch, and thermosensation, as well as itch. Relative to the extensive studies on TRPV1 and TRPA1 ion channels in itch modulation, TRPV4 has received relatively little research attention and its mechanisms have remained poorly understood until recently. TRPV4 is expressed in ganglion sensory neurons and a variety of skin cells. Growing evidence in the past few years strongly suggests that TRPV4 in these cells contributes to acute and chronic disease-associated itch. This review focuses on the current experimental evidence involving TRPV4 in itch under pathophysiological conditions and discusses its possible cellular and molecular mechanisms.

2019 ◽  
Vol 20 (17) ◽  
pp. 4285
Author(s):  
Yury A. Trofimov ◽  
Nikolay A. Krylov ◽  
Roman G. Efremov

Solvation effects play a key role in chemical and biological processes. The microscopic properties of water near molecular surfaces are radically different from those in the bulk. Furthermore, the behavior of water in confined volumes of a nanometer scale, including transmembrane pores of ion channels, is especially nontrivial. Knowledge at the molecular level of structural and dynamic parameters of water in such systems is necessary to understand the mechanisms of ion channels functioning. In this work, the results of molecular dynamics (MD) simulations of water in the pore and selectivity filter domains of TRPV1 (Transient Receptor Potential Vanilloid type 1) membrane channel are considered. These domains represent nanoscale volumes with strongly amphiphilic walls, where physical behavior of water radically differs from that of free hydration (e.g., at protein interfaces) or in the bulk. Inside the pore and filter domains, water reveals a very heterogeneous spatial distribution and unusual dynamics: It forms compact areas localized near polar groups of particular residues. Residence time of water molecules in such areas is at least 1.5 to 3 times larger than that observed for similar groups at the protein surface. Presumably, these water “blobs” play an important role in the functional activity of TRPV1. In particular, they take part in hydration of the hydrophobic TRPV1 pore by localizing up to six waters near the so-called “lower gate” of the channel and reducing by this way the free energy barrier for ion and water transport. Although the channel is formed by four identical protein subunits, which are symmetrically packed in the initial experimental 3D structure, in the course of MD simulations, hydration of the same amino acid residues of individual subunits may differ significantly. This greatly affects the microscopic picture of the distribution of water in the channel and, potentially, the mechanism of its functioning. Therefore, reconstruction of the full picture of TRPV1 channel solvation requires thorough atomistic simulations and analysis. It is important that the naturally occurring porous volumes, like ion-conducting protein domains, reveal much more sophisticated and fine-tuned regulation of solvation than, e.g., artificially designed carbon nanotubes.


2006 ◽  
Vol 85 (10) ◽  
pp. 900-904 ◽  
Author(s):  
C.-K. Park ◽  
H.Y. Li ◽  
K.-Y. Yeon ◽  
S.J. Jung ◽  
S.-Y. Choi ◽  
...  

Although eugenol is widely used in dentistry, little is known about the molecular mechanisms responsible for its anesthetic properties. In addition to calcium channels, recently demonstrated by our group, there could be another molecular target for eugenol. Using a whole-cell patch-clamp technique, we investigated the effect of eugenol on voltage-gated sodium channel currents ( I Na) in rat dental primary afferent neurons identified by retrograde labeling with a fluorescent dye in maxillary molars. Eugenol inhibited action potentials and I Na in both capsaicin-sensitive and capsaicin-insensitive neurons. The pre-treatment with capsazepine, a competitive antagonist of transient receptor potential vanilloid 1 (TRPV1), failed to block the inhibitory effect of eugenol on I Na, suggesting no involvement of TRPV1. Two types of I Na, tetrodotoxin (TTX)-resistant and TTX-sensitive I Na, were inhibited by eugenol. Our results demonstrated that eugenol inhibits I Na in a TRPV1-independent manner. We suggest that I Na inhibition by eugenol contributes to its analgesic effect.


2007 ◽  
Vol 292 (1) ◽  
pp. R64-R76 ◽  
Author(s):  
Michael J. Caterina

Living organisms must evaluate changes in environmental and internal temperatures to mount appropriate physiological and behavioral responses conducive to survival. Classical physiology has provided a wealth of information regarding the specialization of thermosensory functions among subclasses of peripheral sensory neurons and intrinsically thermosensitive neurons within the hypothalamus. However, until recently, the molecular mechanisms by which these cells carry out thermometry have remained poorly understood. The demonstration that certain ion channels of the transient receptor potential (TRP) family can be activated by increases or decreases in ambient temperature, along with the recognition of their heterogeneous expression patterns and heterogeneous temperature sensitivities, has led investigators to evaluate these proteins as candidate endogenous thermosensors. Much of this work has involved one specific channel, TRP vanilloid 1 (TRPV1), which is both a receptor for capsaicin and related pungent vanilloid compounds and a “heat receptor,” capable of directly depolarizing neurons in response to temperatures >42°C. Evidence for a contribution of TRPV1 to peripheral thermosensation has come from pharmacological, physiological, and genetic approaches. In contrast, although capsaicin-sensitive mechanisms clearly influence core body temperature regulation, the specific contribution of TRPV1 to this process remains a matter of debate. Besides TRPV1, at least six additional thermally sensitive TRP channels have been identified in mammals, and many of these also appear to participate in thermosensation. Moreover, the identification of invertebrate TRP channels, whose genetic ablation alters thermally driven behaviors, makes it clear that thermosensation represents an evolutionarily conserved role of this ion channel family.


2018 ◽  
Vol 120 (3) ◽  
pp. 1198-1211 ◽  
Author(s):  
Ileana Hernández-Araiza ◽  
Sara L. Morales-Lázaro ◽  
Jesús Aldair Canul-Sánchez ◽  
León D. Islas ◽  
Tamara Rosenbaum

Lysophosphatidic acid (LPA) is a bioactive phospholipid that exhibits a wide array of functions that include regulation of protein synthesis and adequate development of organisms. LPA is present in the membranes of cells and in the serum of several mammals and has also been shown to participate importantly in pathophysiological conditions. For several decades it was known that LPA produces some of its effects in cells through its interaction with specific G protein-coupled receptors, which in turn are responsible for signaling pathways that regulate cellular function. Among the target proteins for LPA receptors are ion channels that modulate diverse aspects of the physiology of cells and organs where they are expressed. However, recent studies have begun to unveil direct effects of LPA on ion channels, highlighting this phospholipid as a direct agonist and adding to the knowledge of the field of lipid-protein interactions. Moreover, the roles of LPA in pathophysiological conditions associated with the function of some ion channels have also begun to be clarified, and molecular mechanisms have been identified. This review focuses on the effects of LPA on ion channel function under normal and pathological conditions and highlights our present knowledge of the mechanisms by which it regulates the function and expression of N- and T-type Ca++ channels; M-type K+ channel and inward rectifier K+ channel subunit 2.1; transient receptor potential (TRP) melastatin 2, TRP vanilloid 1, and TRP ankyrin 1 channels; and TWIK-related K+ channel 1 (TREK-1), TREK-2, TWIK-related spinal cord K+ channel (TRESK), and TWIK-related arachidonic acid-stimulated K+ channel (TRAAK).


2010 ◽  
Vol 112 (3) ◽  
pp. 729-741 ◽  
Author(s):  
John P. M. White ◽  
Mario Cibelli ◽  
Antonio Rei Fidalgo ◽  
Cleoper C. Paule ◽  
Faruq Noormohamed ◽  
...  

Pain originating in inflammation is the most common pathologic pain condition encountered by the anesthesiologist whether in the context of surgery, its aftermath, or in the practice of pain medicine. Inflammatory agents, released as components of the body's response to peripheral tissue damage or disease, are now known to be collectively capable of activating transient receptor potential vanilloid type 1, transient receptor potential vanilloid type 4, transient receptor potential ankyrin type 1, and acid-sensing ion channels, whereas individual agents may activate only certain of these ion channels. These ionotropic receptors serve many physiologic functions-as, indeed, do many of the inflammagens released in the inflammatory process. Here, we introduce the reader to the role of these ionotropic receptors in mediating peripheral pain in response to inflammation.


2020 ◽  
Vol 21 (3) ◽  
pp. 1005 ◽  
Author(s):  
Péter Sántha ◽  
Ildikó Dobos ◽  
Gyöngyi Kis ◽  
Gábor Jancsó

Gangliosides are abundantly occurring sialylated glycosphingolipids serving diverse functions in the nervous system. Membrane-localized gangliosides are important components of lipid microdomains (rafts) which determine the distribution of and the interaction among specific membrane proteins. Different classes of gangliosides are expressed in nociceptive primary sensory neurons involved in the transmission of nerve impulses evoked by noxious mechanical, thermal, and chemical stimuli. Gangliosides, in particular GM1, have been shown to participate in the regulation of the function of ion channels, such as transient receptor potential vanilloid type 1 (TRPV1), a molecular integrator of noxious stimuli of distinct nature. Gangliosides may influence nociceptive functions through their association with lipid rafts participating in the organization of functional assemblies of specific nociceptive ion channels with neurotrophins, membrane receptors, and intracellular signaling pathways. Genetic and experimentally induced alterations in the expression and/or metabolism of distinct ganglioside species are involved in pathologies associated with nerve injuries, neuropathic, and inflammatory pain in both men and animals. Genetic and/or pharmacological manipulation of neuronal ganglioside expression, metabolism, and action may offer a novel approach to understanding and management of pain.


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