Natural product ligands of TRP channels

EGFR Tyrosine Kinase Inhibitor Lazertinib Activates a Subset of Mouse Sensory Neurons Via TRPA1

Lazertinib (JNJ-73841937, YH25448) is a mutant-selective irreversible epidermal growth factor receptor tyrosine kinase inhibitor targeting both the T790M and activating mutation while sparing wild-type epidermal growth factor receptor. Paresthesia is one of the most common adverse events seen with lazertinib treatment, suggesting that lazertinib could affect the sensory nervous system. However, the mechanism of action for this paresthesia remains unclear. In this study, we investigated whether and how lazertinib affects peripheral sensory neurons. Through Fura-2-based calcium imaging and whole-cell patch clamp recording in primary-cultured dorsal root ganglion (DRG) neurons from adult mice, we found that application of lazertinib elicits spontaneous calcium responses in a subset of small-to-medium-sized neurons. Moreover, lazertinib induced spontaneous firings and hyperexcitability in a subset of transient receptor potential vanilloid 1-lineage DRG neurons and sensitized transient receptor potential ankyrin 1 (TRPA1) response, while sparing transient receptor potential vanilloid 1 response. Lazertinib-responsive neurons were also responsive to capsaicin, further supporting that lazertinib selectively activates nociceptive neurons. Lazertinib-induced calcium responses were pharmacologically blocked with HC-030031 (TRPA1 antagonist) and MDL-12330A (adenylyl cyclase inhibitor), suggesting that lazertinib activates sensory neurons through indirect activation of TRPA1. However, unlike vincristine which produces peripheral neuropathy by axonal degeneration, lazertinib did not cause neurite fragmentation in cultured DRG neurons. Finally, intraplantar injection of lazertinib induced TRPA1-dependent pain-like behaviors in vivo. Collectively, our data suggest a direct effect of lazertinib on nociceptive sensory neurons via TRPA1 selective mechanisms, which could be a putative mechanism of lazertinib-induced sensory abnormalities in clinical patients. PERSPECTIVE: This article presents a TRPA1-dependent, lazertinib-induced activation of mouse sensory neurons in vitro and lazertinib-induced pain-like behaviors in vivo. The same mechanisms may underlie the clinical condition, suggesting that TRPA1 could be a potential therapeutic target to manage lazertinib-induced paresthesia.

Targeting TRP channels: recent advances in structure, ligand binding, and molecular mechanisms

Transient receptor potential (TRP) channels are a large and diverse family of transmembrane ion channels that are widely expressed, have important physiological roles, and are associated with many human diseases. These proteins are actively pursued as promising drug targets, benefitting greatly from advances in structural and mechanistic studies of TRP channels. At the same time, the complex, polymodal activation and regulation of TRP channels have presented formidable challenges. In this short review, we summarize recent progresses toward understanding the structural basis of TRP channel function, as well as potential ligand binding sites that could be targeted for therapeutics. A particular focus is on the current understanding of the molecular mechanisms of TRP channel activation and regulation, where many fundamental questions remain unanswered. We believe that a deeper understanding of the functional mechanisms of TRP channels will be critical and likely transformative toward developing successful therapeutic strategies targeting these exciting proteins. This endeavor will require concerted efforts from computation, structural biology, medicinal chemistry, electrophysiology, pharmacology, drug safety and clinical studies.

Targeting temperature-sensitive transient receptor potential channels in hypertension: far beyond the perception of hot and cold

Transient receptor potential (TRP) channels are nonselective cation channels and participate in various physiological roles. Thus, changes in TRP channel function or expression have been linked to several disorders. Among the many TRP channel subtypes, the TRP ankyrin type 1 (TRPA1), TRP melastatin type 8 (TRPM8), and TRP vanilloid type 1 (TRPV1) channels are temperature-sensitive and recognized as thermo-TRPs, which are expressed in the primary afferent nerve. Thermal stimuli are converted into neuronal activity. Several studies have described the expression of TRPA1, TRPM8, and TRPV1 in the cardiovascular system, where these channels can modulate physiological and pathological conditions, including hypertension. This review provides a complete understanding of the functional role of the opposing thermo-receptors TRPA1/TRPM8/TRPV1 in hypertension and a more comprehensive appreciation of TRPA1/TRPM8/TRPV1-dependent mechanisms involved in hypertension. These channels varied activation and inactivation have revealed a signaling pathway that may lead to innovative future treatment options for hypertension and correlated vascular diseases.

TRP channels: a journey towards a molecular understanding of pain

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.

Sensory TRP Channels in Three Dimensions

Transient receptor potential (TRP) ion channels are sophisticated signaling machines that detect a wide variety of environmental and physiological signals. Every cell in the body expresses one or more members of the extended TRP channel family, which consists of over 30 subtypes, each likely possessing distinct pharmacological, biophysical, and/or structural attributes. While the function of some TRP subtypes remains enigmatic, those involved in sensory signaling are perhaps best characterized and have served as models for understanding how these excitatory ion channels serve as polymodal signal integrators. With the recent resolution revolution in cryo-electron microscopy, these and other TRP channel subtypes are now yielding their secrets to detailed atomic analysis, which is beginning to reveal structural underpinnings of stimulus detection and gating, ion permeation, and allosteric mechanisms governing signal integration. These insights are providing a framework for designing and evaluating modality-specific pharmacological agents for treating sensory and other TRP channel-associated disorders.

Transient Receptor Potential (TRP) Channels in the Pacific Oyster (Crassostrea gigas): Genome-Wide Identification and Expression Profiling after Heat Stress between C. gigas and C. angulata

Transmembrane proteins are involved in an array of stress responses, particularly in thermo-sensation and thermo-regulation. In this study, we performed a genome-wide identification and characterization of the Transient Receptor Potential (TRP) genes in the Pacific oyster (Crassostrea gigas) and investigated their expression profiles after heat stress to identify critical TRPs potentially associated with thermal regulation. A total of 66 TRP genes were identified in the C. gigas, which showed significant gene expansion and tandem duplication. Meta-analysis of the available RNA-Seq data generated from samples after acute heat stress revealed a set of heat-inducible TRPs. Further examination of their expression profiles under chronic heat stress, and comparison between C. gigas and C. angulata, two oyster species with different tolerance levels to heat stress, led to the identification of TRPC3.6, TRPC3.7, and TRPV4.7 as important TRPs involved in thermal regulation in oysters. This work provided valuable information for future studies on the molecular mechanism of TRP mediated thermal tolerance, and identification of diagnostic biomarker for thermal stress in the oysters.

Validation of an LC-MS/MS Method to Quantify the New TRPC6 Inhibitor SH045 (Larixyl N-methylcarbamate) and Its Application in an Exploratory Pharmacokinetic Study in Mice

TRPC6 (transient receptor potential cation channels; canonical subfamily C, member 6) is widespread localized in mammalian tissues like kidney and lung and associated with progressive proteinuria and pathophysiological pulmonary alterations, e.g., reperfusion edema or lung fibrosis. However, the understanding of TRPC6 channelopathies is still at the beginning stages. Recently, by chemical diversification of (+)-larixol originating from Larix decidua resin traditionally used for inhalation, its methylcarbamate congener, named SH045, was obtained and identified in functional assays as a highly potent, subtype-selective inhibitor of TRPC6. To pave the way for use of SH045 in animal disease models, this study aimed at developing a capable bioanalytical method and to provide exploratory pharmacokinetic data for this promising derivative. According to international guidelines, a robust and selective LC-MS/MS method based on MRM detection in positive ion mode was established and validated for quantification of SH045 in mice plasma, whereby linearity and accuracy were demonstrated for the range of 2–1600 ng/mL. Applying this method, the plasma concentration time course of SH045 following single intraperitoneal administration (20 mg/kg body weight) revealed a short half-life of 1.3 h. However, the pharmacological profile of SH045 is promising, as five hours after administration, plasma levels still remained sufficiently higher than published low nanomolar IC₅₀ values. Summarizing, the LC-MS/MS method and exploratory pharmacokinetic data provide essential prerequisites for experimental pharmacological TRPC6 modulation and translational treatment of TRPC6 channelopathies.

New natural agonists of the transient receptor potential Ankyrin 1 (TRPA1) channel

The transient receptor potential (TRP) channels family are cationic channels involved in various physiological processes as pain, inflammation, metabolism, swallowing function, gut motility, thermoregulation or adipogenesis. In the oral cavity, TRP channels are involved in chemesthesis, the sensory chemical transduction of spicy ingredients. Among them, TRPA1 is activated by natural molecules producing pungent, tingling or irritating sensations during their consumption. TRPA1 can be activated by different chemicals found in plants or spices such as the electrophiles isothiocyanates, thiosulfinates or unsaturated aldehydes. TRPA1 has been as well associated to various physiological mechanisms like gut motility, inflammation or pain. Cinnamaldehyde, its well known potent agonist from cinnamon, is reported to impact metabolism and exert anti-obesity and anti-hyperglycemic effects. Recently, a structurally similar molecule to cinnamaldehyde, cuminaldehyde was shown to possess anti-obesity and anti-hyperglycemic effect as well. We hypothesized that both cinnamaldehyde and cuminaldehyde might exert this metabolic effects through TRPA1 activation and evaluated the impact of cuminaldehyde on TRPA1. The results presented here show that cuminaldehyde activates TRPA1 as well. Additionally, a new natural agonist of TRPA1, tiglic aldehyde, was identified and p-anisaldehyde confirmed.

Lipid Interactions of a Ciliary Membrane TRP Channel: Simulation and Structural Studies of Polycystin-2

Polycystin-2 (PC2) is a transient receptor potential (TRP) channel present in ciliary membranes of the kidney. PC2 shares a transmembrane fold with other TRP channels, in addition to an extracellular domain found in TRPP and TRPML channels. Using molecular dynamics (MD) simulations and cryoelectron microscopy we identify and characterize PIP₂ and cholesterol interactions with PC2. PC2 is revealed to have a PIP binding site close to the equivalent vanilloid/lipid binding site in the TRPV1 channel. A 3.0-Å structure reveals a binding site for cholesterol on PC2. Cholesterol interactions with the channel at this site are characterized by MD simulations. The two classes of lipid binding sites are compared with sites observed in other TRPs and in Kv channels. These findings suggest PC2, in common with other ion channels, may be modulated by both PIPs and cholesterol, and position PC2 within an emerging model of the roles of lipids in the regulation and organization of ciliary membranes.

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Lipid interactions of PC2 channels have been explored by MD simulation and cryo-EM

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PIP₂ binds to a site corresponding to the vanilloid/lipid binding site of TRPV1

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Cholesterol binds between the S3 and S4 helices and S6 of the adjacent subunit

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PC2, in common with other channels, may be modulated by PIPs and cholesterol

Individual differences in the perception of orthonasal irritation induced by food

Oral responsiveness to the burning/spicy sensation affects food behaviors and diet; therefore, it is reasonable to hypothesize that the variation in nasal responsiveness to irritant foods may play a role in modulating food behaviors. This study explored the variation among individuals in orthonasal irritation induced by smelling food ingredients containing irritant compounds: mustard oil (2.0, 10.0, and 100.0% v/v mustard oil in corn oil; irritant compound: allyl isothiocyanate); vinegar (3.5, 42.3, and 98.6% v/v vinegar in water; irritant compound: acetic acid); and wasabi (0.1, 0.2, and 0.4% w/w wasabi powder in water; irritant compound: allyl isothiocyanate). Sixty-eight subjects (40% males; 19-87 years) smelled the nine samples and rated their perceived intensity of odor, irritation and liking. Wide individual variation in the perception of irritation and odor intensity was found, especially at the highest concentrations. Young individuals were the most sensitive to all stimuli. No significant differences were found between males and females. Fifty-seven percent of subjects were "HYPO" and 43 percent "HYPER" responsive to irritation, respectively. Perceived irritation was positively correlated with odor intensity and tended to be negatively correlated with liking, especially in familiar stimuli. The results suggest that the variation in nasal responsiveness to irritant foods may contribute to influencing food acceptance and therefore, to modulating food behaviors.

TRP Channels: Current Perspectives in the Adverse Cardiac Remodeling

Calcium is an important second messenger required not only for the excitation-contraction coupling of the heart but also critical for the activation of cell signaling pathways involved in the adverse cardiac remodeling and consequently for the heart failure. Sustained neurohumoral activation, pressure-overload, or myocardial injury can cause pathologic hypertrophic growth of the heart followed by interstitial fibrosis. The consequent heart’s structural and molecular adaptation might elevate the risk of developing heart failure and malignant arrhythmia. Compelling evidences have demonstrated that Ca²⁺ entry through TRP channels might play pivotal roles in cardiac function and pathology. TRP proteins are classified into six subfamilies: TRPC (canonical), TRPV (vanilloid), TRPM (melastatin), TRPA (ankyrin), TRPML (mucolipin), and TRPP (polycystin), which are activated by numerous physical and/or chemical stimuli. TRP channels participate to the handling of the intracellular Ca²⁺ concentration in cardiac myocytes and are mediators of different cardiovascular alterations. This review provides an overview of the current knowledge of TRP proteins implication in the pathologic process of some frequent cardiac diseases associated with the adverse cardiac remodeling such as cardiac hypertrophy, fibrosis, and conduction alteration.

TRP Channels in Angiogenesis and Other Endothelial Functions

Angiogenesis is the growth of blood vessels mediated by proliferation, migration, and spatial organization of endothelial cells. This mechanism is regulated by a balance between stimulatory and inhibitory factors. Proangiogenic factors include a variety of VEGF family members, while thrombospondin and endostatin, among others, have been reported as suppressors of angiogenesis. Transient receptor potential (TRP) channels belong to a superfamily of cation-permeable channels that play a relevant role in a number of cellular functions mostly derived from their influence in intracellular Ca²⁺ homeostasis. Endothelial cells express a variety of TRP channels, including members of the TRPC, TRPV, TRPP, TRPA, and TRPM families, which play a relevant role in a number of functions, including endothelium-induced vasodilation, vascular permeability as well as sensing hemodynamic and chemical changes. Furthermore, TRP channels have been reported to play an important role in angiogenesis. This review summarizes the current knowledge and limitations concerning the involvement of particular TRP channels in growth factor-induced angiogenesis.

TRPA1 Modulating C14 Polyacetylenes from the Iranian Endemic Plant Echinophora platyloba

Phytochemical investigation of the apolar extract obtained from aerial parts of the Iranian endemic plant Echinophora platyloba DC (Apiaceae) resulted in the characterization of the polyacetylene fraction of this plant. This resulted to be composed of the known echinophorins A and B, embedding the very rare α-pyrone terminal, and of the new echinophorin D (3), including also three conjugated triple bonds. The chemical structures of these compounds were secured by detailed inspection of MS and 1D/2D NMR spectra. The isolated polyacteylenes were evaluated for their modulation of six thermo-TRP channels and they revealed a selective activity on TRPA1, an ion channel involved in the mediation of neuropathic and inflammatory pain. This is the first report on the activity of plant polyacetylenes on transient receptor potential (TRP) channels.

A (+)-Larixol Congener with High Affinity and Subtype Selectivity toward TRPC6

Natural products have many health benefits, and their application can improve the quality of life. Recently, the diterpene (+)-larixol and its acetylated congeners demonstrated selective inhibition of the second-messenger-gated cation channel transient receptor potential canonical 6 (TRPC6) over its close isoforms TRPC3 and TRPC7. Building on this knowledge, we expanded these findings by chemical diversification of (+)-larixol mostly at position C6. Implementing high-throughput Ca²⁺ FLIPR screening assays and electrophysiological patch-clamp recordings, we showcase larixyl N-methylcarbamate, termed SH045, as a compound with nanomolar affinity and 13-fold subtype selectivity over TRPC3 in stably expressing HEK293 cells. Expanding on this finding, TRPC6 inhibition was also observed in rat pulmonary smooth muscle cells. Furthermore, treatment of isolated perfused lung preparations with SH045 led to a decrease in lung ischemia-reperfusion edema (LIRE), a life-threatening condition associated with TRPC6 that may occur after organ transplantation. Taken together, and given the inexpensive, straightforward, and scalable preparation of SH045, we report a TRPC6 blocker that holds promise for the translational treatment of LIRE.

Natural product modulators of human sensations and mood: molecular mechanisms and therapeutic potential

Humans perceive physical information about the surrounding environment through their senses. This physical information is registered by a collection of highly evolved and finely tuned molecular sensory receptors. A multitude of bioactive, structurally diverse ligands have evolved in nature that bind these molecular receptors. The complex, dynamic interactions between the ligands and the receptors lead to changes in our sensory perception or mood. Here, we review our current knowledge of natural products and their derived analogues that interact specifically with human G protein-coupled receptors, ion channels, and nuclear hormone receptors to modulate the sensations of taste, smell, temperature, pain, and itch, as well as mood and its associated behaviour. We discuss the molecular and structural mechanisms underlying such interactions and highlight cases where subtle differences in natural product chemistry produce drastic changes in functional outcome. We also discuss cases where a single compound triggers complex sensory or behavioural changes in humans through multiple mechanistic targets. Finally, we comment on the therapeutic potential of the reviewed area of research and draw attention to recent technological developments in genomics, metabolomics, and metabolic engineering that allow us to tap the medicinal properties of natural product chemistry without taxing nature.

Involvement of thermosensitive TRP channels in energy metabolism

To date, 11 thermosensitive transient receptor potential (thermo-TRP) channels have been identified. Recent studies have characterized the mechanism of thermosensing by thermo-TRPs and the physiological role of thermo-TRPs in energy metabolism. In this review, we highlight the role of various thermo-TRPs in energy metabolism and hormone secretion. In the pancreas, TRPM2 and other TRPs regulate insulin secretion. TRPV2 expressed in brown adipocytes contributes to differentiation and/or thermogenesis. Sensory nerves that express TRPV1 promote increased energy expenditure by activating sympathetic nerves and adrenaline secretion. Here, we first show that capsaicin-induced adrenaline secretion is completely impaired in TRPV1 knockout mice. The thermogenic effects of TRPV1 agonists are attributable to brown adipose tissue (BAT) activation in mice and humans. Moreover, TRPA1- and TRPM8-expressing sensory nerves also contribute to potentiation of BAT thermogenesis and energy expenditure in mice. Together, thermo-TRPs are promising targets for combating obesity and metabolic disorders.

TRPs in Pain Sensation

According to the International Association for the Study of Pain (IASP) pain is characterized as an "unpleasant sensory and emotional experience associated with actual or potential tissue damage". The TRP super-family, compressing up to 28 isoforms in mammals, mediates a myriad of physiological and pathophysiological processes, pain among them. TRP channel might be constituted by similar or different TRP subunits, which will result in the formation of homomeric or heteromeric channels with distinct properties and functions. In this review we will discuss about the function of TRPs in pain, focusing on TRP channles that participate in the transduction of noxious sensation, especially TRPV1 and TRPA1, their expression in nociceptors and their sensitivity to a large number of physical and chemical stimuli.

Extraoral Taste Receptor Discovery: New Light on Ayurvedic Pharmacology

More and more research studies are revealing unexpectedly important roles of taste for health and pathogenesis of various diseases. Only recently it has been shown that taste receptors have many extraoral locations (e.g., stomach, intestines, liver, pancreas, respiratory system, heart, brain, kidney, urinary bladder, pancreas, adipose tissue, testis, and ovary), being part of a large diffuse chemosensory system. The functional implications of these taste receptors widely dispersed in various organs or tissues shed a new light on several concepts used in ayurvedic pharmacology (dravyaguna vijnana), such as taste (rasa), postdigestive effect (vipaka), qualities (guna), and energetic nature (virya). This review summarizes the significance of extraoral taste receptors and transient receptor potential (TRP) channels for ayurvedic pharmacology, as well as the biological activities of various types of phytochemical tastants from an ayurvedic perspective. The relative importance of taste (rasa), postdigestive effect (vipaka), and energetic nature (virya) as ethnopharmacological descriptors within Ayurveda boundaries will also be discussed.

Effects of TRP channel agonist ingestion on metabolism and autonomic nervous system in a randomized clinical trial of healthy subjects

Various lines of published evidence have already demonstrated the impact of TRPV1 agonists on energetic metabolism through the stimulation of the sympathetic nervous system (SNS). This study presents a trial investigating if stimulation of the two related sensory receptors TRPA1 and TRPM8 could also stimulate the SNS and impact the energetic metabolism of healthy subjects. The trial was designed to be double-blinded, randomized, cross-over, placebo-controlled with healthy subjects and the impact on the energetic metabolism and the autonomic nervous system (ANS) of cinnamaldehyde, capsaicin and a cooling flavor was measured during the 90 min after ingestion. Energy expenditure and substrate oxidation were measured by indirect calorimetry. An exploratory method to measure ANS activity was by facial thermography and power spectral analysis of heart rate variability using ECG was also used. Following cinnamaldehyde ingestion, energy expenditure was increased as compared to placebo. Furthermore, postprandial fat oxidation was maintained higher compared to placebo after cinnamaldehyde and capsaicin ingestion. Similar peripheral thermoregulation was observed after capsaicin and cinnamaldehyde ingestion. Unlike capsaicin, the dose of cinnamaldehyde was not judged to be sensorially ‘too intense’ by participants suggesting that Cinnamaldehyde would be a more tolerable solution to improve thermogenesis via spicy ingredients as compared to capsaicin.

Central administration of nicotine suppresses tracheobronchial cough in anesthetized cats

We tested the hypothesis that nicotine, which acts peripherally to promote coughing, might inhibit reflex cough at a central site. Nicotine was administered via the vertebral artery [intra-arterial (ia)] to the brain stem circulation and by microinjections into a restricted area of the caudal ventral respiratory column in 33 pentobarbital anesthetized, spontaneously breathing cats. The number of coughs induced by mechanical stimulation of the tracheobronchial airways; amplitudes of the diaphragm, abdominal muscle, and laryngeal muscles EMGs; and several temporal characteristics of cough were analyzed after administration of nicotine and compared with those during control and recovery period. (-)Nicotine (ia) reduced cough number, cough expiratory efforts, blood pressure, and heart rate in a dose-dependent manner. (-)Nicotine did not alter temporal characteristics of the cough motor pattern. Pretreatment with mecamylamine prevented the effect of (-)nicotine on blood pressure and heart rate, but did not block the antitussive action of this drug. (+)Nicotine was less potent than (-)nicotine for inhibition of cough. Microinjections of (-)nicotine into the caudal ventral respiratory column produced similar inhibitory effects on cough as administration of this isomer by the ia route. Mecamylamine microinjected in the region just before nicotine did not significantly reduce the cough suppressant effect of nicotine. Nicotinic acetylcholine receptors significantly modulate functions of brain stem and in particular caudal ventral respiratory column neurons involved in expression of the tracheobronchial cough reflex by a mecamylamine-insensitive mechanism.

TRPs in taste and chemesthesis

TRP channels are expressed in taste buds, nerve fibers, and keratinocytes in the oronasal cavity. These channels play integral roles in transducing chemical stimuli, giving rise to sensations of taste, irritation, warmth, coolness, and pungency. Specifically, TRPM5 acts downstream of taste receptors in the taste transduction pathway. TRPM5 channels convert taste-evoked intracellular Ca(2+) release into membrane depolarization to trigger taste transmitter secretion. PKD2L1 is expressed in acid-sensitive (sour) taste bud cells but is unlikely to be the transducer for sour taste. TRPV1 is a receptor for pungent chemical stimuli such as capsaicin and for several irritants (chemesthesis). It is controversial whether TRPV1 is present in the taste buds and plays a direct role in taste. Instead, TRPV1 is expressed in non-gustatory sensory afferent fibers and in keratinocytes of the oronasal cavity. In many sensory fibers and epithelial cells lining the oronasal cavity, TRPA1 is also co-expressed with TRPV1. As with TRPV1, TRPA1 transduces a wide variety of irritants and, in combination with TRPV1, assures that there is a broad response to noxious chemical stimuli. Other TRP channels, including TRPM8, TRPV3, and TRPV4, play less prominent roles in chemesthesis and no known role in taste, per se. The pungency of foods and beverages is likely highly influenced by the temperature at which they are consumed, their acidity, and, for beverages, their carbonation. All these factors modulate the activity of TRP channels in taste buds and in the oronasal mucosa.

Effect of acyclic monoterpene alcohols and their derivatives on TRP channels

A series of thirty-six geraniol, nerol, citronellol, geranylamine, and nerylamine derivatives was synthesized and tested on TRPA1, TRPM8, and TRPV1 channels. Most of them acted as strong modulators of TRPA1 channels with EC50 and/or IC50 values <1 μM. None was able to significantly activate TRPM8 channels, while thirteen of them behaved as 'true' TRPM8 antagonists. Little or no effect was generally observed on TRPV1 channels. Some of the compounds examined, that is, compounds 1d,g,n, 2c,d,h,i,o, 3b,e exhibited an appreciable selectivity for TRPA1 subtype.

Leucettamols, bifunctionalized marine sphingoids, act as modulators of TRPA1 and TRPM8 channels

Leucettamols, bifunctionalized sphingoid-like compounds obtained from a marine sponge Leucetta sp., act as non-electrophilic activators of the TRPA1 channel and potent inhibitors of the icilin-mediated activation of the TRPM8 channel, while they are inactive on CB₁, CB₂ and TRPV1 receptors. Leucettamols represent the first compounds of marine origin to target TRPA1 and the first class of natural products to inhibit TRPM8 channels. The preparation of a small series of semi-synthetic derivatives revealed interesting details on the structure-activity relationships within this new chemotype of simple acyclic TRP modulators.

Plasma membrane ion fluxes and NFAT-dependent gene transcription contribute to c-met-induced epithelial scattering

Hepatocyte growth factor (HGF) signaling drives epithelial cells to scatter by breaking cell-cell adhesions and causing them to migrate as solitary cells, a process that parallels epithelial-mesenchymal transition. HGF binds and activates the c-met receptor tyrosine kinase, but downstream signaling required for scattering remains poorly defined. We have applied a chemical biology approach to identify components of HGF signaling that are required for scattering in an in vitro model system. This approach yields a number of small molecules that block HGF-induced scattering, including a calcium channel blocker. We show that HGF stimulation results in sudden and transient increases in ion channel influxes at the plasma membrane. Although multiple channels occur in the membranes of our model system, we find that TrpC6 is specifically required for HGF-induced scattering. We further demonstrate that HGF-induced ion influxes through TrpC6 channels coincide with a transient increase in nuclear factor of activated T-cells (NFAT)-dependent gene transcription and that NFAT-dependent gene transcription is required for HGF-induced cell scattering.

Modulation of thermo-transient receptor potential (thermo-TRP) channels by thymol-based compounds

A series of thirty-three thymol, p-cymene-3-carboxylic acid, and 3-amino-p-cymene derivatives was synthesized and tested on TRPA1, TRPM8, and TRPV3 channels. Most of them acted as strong modulators of TRPA1, TRPM8, and TRPV3 channels with EC(50) and/or IC(50) values distinctly lower than those of thymol and related monoterpenoids. Some of the compounds examined, that is, 3c, 4e, f, 6b, and 8b exhibited an appreciable subtype-selectivity.