Transient Receptor Potential Ankyrin 1 Channel Research Articles

Transient receptor potential ankyrin 1 (TRPA1) mediates reactive oxygen species-induced Ca2+ entry, mitochondrial dysfunction, and caspase-3/7 activation in primary cultures of metastatic colorectal carcinoma cells

Colorectal carcinoma (CRC) represents the fourth most common cancer worldwide and is the third most common cause of malignancy-associated mortality. Distant metastases to the liver and lungs are the main drivers of CRC-dependent death. Pro-oxidant therapies, which halt disease progression by exacerbating oxidative stress, represent an antitumour strategy that is currently exploited by chemotherapy and ionizing radiation. A more selective strategy to therapeutically exploit reactive oxygen species (ROS) signaling would consist in targeting a redox sensor that is up-regulated in metastatic cells and is tightly coupled to the stimulation of cancer cell death programs. The non-selective cation channel, Transient Receptor Potential Ankyrin 1 (TRPA1), serves as a sensor of the cellular redox state, being activated to promote extracellular Ca2+ entry by an increase in oxidative stress. Recent work demonstrated that TRPA1 channel protein is up-regulated in several cancer types and that TRPA1-mediated Ca2+ signals can either engage an antiapoptotic pro-survival signaling pathway or to promote mitochondrial Ca2+ dysfunction and apoptosis. Herein, we sought to assess for the first time the outcome of TRPA1 activation by ROS on primary cultures of metastatic colorectal carcinoma (mCRC cells). We found that TRPA1 channel protein is up-regulated and mediates enhanced hydrogen peroxide (H2O2)-induced Ca2+ entry in mCRC cells as compared to non-neoplastic control cells. The lipid peroxidation product 4-hydroxynonenal (4-HNE) is the main ROS responsible for TRPA1 activation upon mCRC cell exposure to oxidative stress. TRPA1-mediated Ca2+ entry in response to H2O2 and 4-HNE results in mitochondrial Ca2+ overload, followed by mitochondrial depolarization and caspase-3/7 activation. Therefore, targeting TRPA1 could represent an alternative strategy to eradicate metastatic CRC by enhancing its sensitivity to oxidative stress.

Aedes aegypti salivary gland extract alleviates acute itching by blocking TRPA1 channels.

Aedes aegypti (Ae. aegypti) saliva induces a variety of anti-inflammatory and immunomodulatory activities. Interestingly, although it is known that mosquito bites cause allergic reactions in sensitised hosts, the primary exposure of humans to Ae. aegypti does not evoke significant itching. Whether active components in the saliva of Ae. aegypti can counteract the normal itch reaction to injury produced by a histaminergic or non-histaminergic pathway in vertebrate hosts is unknown. This study investigated the effects of Ae. aegypti mosquito salivary gland extract (SGE) on sensitive reactions such as itching and associated skin inflammation. Acute pruritus and plasma extravasation were induced in mice by the intradermal injection of either compound 48/80 (C48/80), the Mas-related G protein-coupled receptor (Mrgpr) agonist chloroquine (CQ), or the transient receptor potential ankyrin 1 (TRPA1) agonist allyl isothiocyanate (AITC). The i.d. co-injection of Ae. aegypti SGE inhibited itching, plasma extravasation, and neutrophil influx evoked by C48/80, but it did not significantly affect mast cell degranulation in situ or in vitro. Additionally, SGE partially reduced CQ- and AITC-induced pruritus in vivo, suggesting that SGE affects pruriceptive nerve firing independently of the histaminergic pathway. Activation of TRPA1 significantly increased intracellular Ca2+ in TRPA-1-transfected HEK293t lineage, which was attenuated by SGE addition. We showed for the first time that Ae. aegypti SGE exerts anti-pruriceptive effects, which are partially regulated by the histamine-independent itch TRPA1 pathway. Thus, SGE may possess bioactive molecules with therapeutic potential for treating nonhistaminergic itch.

Neuropathic-like Nociception and Spinal Cord Neuroinflammation Are Dependent on the TRPA1 Channel in Multiple Sclerosis Models in Mice.

Background: Transient receptor potential ankyrin 1 (TRPA1) activation is implicated in neuropathic pain-like symptoms. However, whether TRPA1 is solely implicated in pain-signaling or contributes to neuroinflammation in multiple sclerosis (MS) is unknown. Here, we evaluated the TRPA1 role in neuroinflammation underlying pain-like symptoms using two different models of MS. Methods: Using a myelin antigen, Trpa1+/+ or Trpa1-/- female mice developed relapsing-remitting experimental autoimmune encephalomyelitis (RR-EAE) (Quil A as adjuvant) or progressive experimental autoimmune encephalomyelitis (PMS)-EAE (complete Freund's adjuvant). The locomotor performance, clinical scores, mechanical/cold allodynia, and neuroinflammatory MS markers were evaluated. Results: Mechanical and cold allodynia detected in RR-EAE, or PMS-EAE Trpa1+/+ mice, were not observed in Trpa1-/- mice. The increased number of cells labeled for ionized calcium-binding adapter molecule 1 (Iba1) or glial fibrillary acidic protein (GFAP), two neuroinflammatory markers in the spinal cord observed in both RR-EAE or PMS-EAE Trpa1+/+ mice, was reduced in Trpa1-/- mice. By Olig2 marker and luxol fast blue staining, prevention of the demyelinating process in Trpa1-/- induced mice was also detected. Conclusions: Present results indicate that the proalgesic role of TRPA1 in EAE mouse models is primarily mediated by its ability to promote spinal neuroinflammation and further strengthen the channel inhibition to treat neuropathic pain in MS.

TRPA1 channel in the airway underlies protection against airborne threats by modulating respiration and behaviour.

Transient receptor potential ankyrin 1 (TRPA1), a member of the TRP superfamily of cation channels, is broadly expressed in sensory neural pathways, including the trigeminal neurons innervating the nasal cavity and vagal neurons innervating the trachea and the lung. TRPA1 acts as a detector of various irritant chemicals as well as hypoxia and hyperoxia. For the past 15years, we have characterised its role in respiratory and behavioural modulation in vivo using Trpa1 knockout (KO) mice and wild-type (WT) littermates. Trpa1 KO mice failed to detect, wake up from sleeping, and escape from formalin vapour and a mild hypoxic (15% O2) environment. Respiratory augmentation induced by mild hypoxia was absent in either Trpa1 KO mice or WT mice treated with a TRPA1 antagonist. Irritant gas introduced into the nasal cavity inhibited respiratory responses in WT mice but not in the KO mice. The effect of TRPA1 on the olfactory system seemed minimal because olfactory bulbectomized WT mice reacted similarly to the intact mice. Immunohistological analyses using a cellar activation marker, the phosphorylated form of extracellular signal-regulated kinase, confirmed activation of trigeminal neurons in WT mice but not in Trpa1 KO mice in response to irritant chemicals and mild hypoxia. These data collectively show that TRPA1 is necessary for multiple chemical-induced protective responses in respiration and behaviour. We propose that TRPA1 channels in the airway may play a sentinel role for environmental threats and prevent incoming damage.

Kinin B2 and B1 Receptors Activation Sensitize the TRPA1 Channel Contributing to Anastrozole-Induced Pain Symptoms.

Aromatase inhibitors (AIs) cause symptoms of musculoskeletal pain, and some mechanisms have been proposed to explain them. However, signaling pathways downstream from kinin B2 (B2R) and B1 (B1R) receptor activation and their possible sensitizing of the Transient Receptor Potential Ankyrin 1 (TRPA1) remain unknown. The interaction between the kinin receptor and the TRPA1 channel in male C57BL/6 mice treated with anastrozole (an AI) was evaluated. PLC/PKC and PKA inhibitors were used to evaluate the signaling pathways downstream from B2R and B1R activation and their effect on TRPA1 sensitization. Anastrozole caused mechanical allodynia and muscle strength loss in mice. B2R (Bradykinin), B1R (DABk), or TRPA1 (AITC) agonists induced overt nociceptive behavior and enhanced and prolonged the painful parameters in anastrozole-treated mice. All painful symptoms were reduced by B2R (Icatibant), B1R (DALBk), or TRPA1 (A967079) antagonists. We observed the interaction between B2R, B1R, and the TRPA1 channel in anastrozole-induced musculoskeletal pain, which was dependent on the activation of the PLC/PKC and PKA signaling pathways. TRPA1 seems to be sensitized by mechanisms dependent on the activation of PLC/PKC, and PKA due to kinin receptors stimulation in anastrozole-treated animals. Thus, regulating this signaling pathway could contribute to alleviating AIs-related pain symptoms, patients' adherence to therapy, and disease control.

Allyl isothiocyanate, an activator of TRPA1, increases gastric mucosal blood flow through calcitonin gene-related peptide and adrenomedullin in anesthetized rats

Allyl isothiocyanate (AITC) activates transient receptor potential ankyrin 1 (TRPA1) channel, which is involved in the control of intestinal mucosal blood flow. However, the mechanism underlying the increased gastric mucosal blood flow (GMBF) in response to AITC remains unknown. We examined the effect of AITC on GMBF in the ex vivo stomachs of normal and sensory deafferented rats using a laser Doppler flowmeter. Mucosal application of AITC increased GMBF in a concentration-dependent manner. Repeated AITC exposure resulted in a marked desensitization. The increased GMBF response induced by AITC was entirely blocked by co-application of TRPA1 channel blockers HC-030031 or AP-18. Increased GMBF in response to AITC was significantly attenuated by chemical deafferentation following systemic capsaicin injections (total dose: 100 mg/kg). In contrast, increased GMBF responses to capsaicin, a transient receptor potential vanilloid 1 (TRPV1) activator, were completely abolished by chemical deafferentation. The increased GMBF response to AITC was markedly inhibited by BIBN 4096, a calcitonin gene-related peptide receptor (CGRP) antagonist, or AGP-8412, an adrenomedullin receptor antagonist. These results suggest that AITC-stimulated TRPA1 activation results in the increased GMBF through the release of CGRP and adrenomedullin.

Inflammation-the role of TRPA1 channel.

Recently, increasing numbers of studies have demonstrated that transient receptor potential ankyrin 1 (TRPA1) can be used as a potential target for the treatment of inflammatory diseases. TRPA1 is expressed in both neuronal and non-neuronal cells and is involved in diverse physiological activities, such as stabilizing of cell membrane potential, maintaining cellular humoral balance, and regulating intercellular signal transduction. TRPA1 is a multi-modal cell membrane receptor that can sense different stimuli, and generate action potential signals after activation via osmotic pressure, temperature, and inflammatory factors. In this study, we introduced the latest research progress on TRPA1 in inflammatory diseases from three different aspects. First, the inflammatory factors released after inflammation interacts with TRPA1 to promote inflammatory response; second, TRPA1 regulates the function of immune cells such as macrophages and T cells, In addition, it has anti-inflammatory and antioxidant effects in some inflammatory diseases. Third, we have summarized the application of antagonists and agonists targeting TRPA1 in the treatment of some inflammatory diseases.

Endothelial cell TRPA1 activity exacerbates cerebral hemorrhage during severe hypertension.

Introduction: Hypoxia-induced dilation of cerebral arteries orchestrated by Ca2+-permeable transient receptor potential ankyrin 1 (TRPA1) cation channels on endothelial cells is neuroprotective during ischemic stroke, but it is unknown if the channel has a similar impact during hemorrhagic stroke. TRPA1 channels are endogenously activated by lipid peroxide metabolites generated by reactive oxygen species (ROS). Uncontrolled hypertension, a primary risk factor for the development of hemorrhagic stroke, is associated with increased ROS production and oxidative stress. Therefore, we hypothesized that TRPA1 channel activity is increased during hemorrhagic stroke. Methods: Severe, chronic hypertension was induced in control (Trpa1 fl/fl) and endothelial cell-specific TRPA1 knockout (Trpa1-ecKO) mice using a combination of chronic angiotensin II administration, a high-salt diet, and the addition of a nitric oxide synthase inhibitor to drinking water. Blood pressure was measured in awake, freely-moving mice using surgically placed radiotelemetry transmitters. TRPA1-dependent cerebral artery dilation was evaluated with pressure myography, and expression of TRPA1 and NADPH oxidase (NOX) isoforms in arteries from both groups was determined using PCR and Western blotting techniques. In addition, ROS generation capacity was evaluated using a lucigenin assay. Histology was performed to examine intracerebral hemorrhage lesion size and location. Results: All animals became hypertensive, and a majority developed intracerebral hemorrhages or died of unknown causes. Baseline blood pressure and responses to the hypertensive stimulus did not differ between groups. Expression of TRPA1 in cerebral arteries from control mice was not altered after 28 days of treatment, but expression of three NOX isoforms and the capacity for ROS generation was increased in hypertensive animals. NOX-dependent activation of TRPA1 channels dilated cerebral arteries from hypertensive animals to a greater extent compared with controls. The number of intracerebral hemorrhage lesions in hypertensive animals did not differ between control and Trpa1-ecKO animals but were significantly smaller in Trpa1-ecKO mice. Morbidity and mortality did not differ between groups. Discussion: We conclude that endothelial cell TRPA1 channel activity increases cerebral blood flow during hypertension resulting in increased extravasation of blood during intracerebral hemorrhage events; however, this effect does not impact overall survival. Our data suggest that blocking TRPA1 channels may not be helpful for treating hypertension-associated hemorrhagic stroke in a clinical setting.

Functionally active TRPA1 ion channel is downregulated in peptidergic neurons of the Edinger-Westphal nucleus upon acute alcohol exposure.

Introduction: The centrally projecting Edinger-Westphal nucleus (EWcp) contributes to the control of alcohol consumption by its urocortin 1 (UCN1) and cocaine- and amphetamine-regulated transcript (CART) co-expressing peptidergic neurons. Our group recently showed that the urocortinergic centrally projecting EWcp is the primary seat of central nervous system transient receptor potential ankyrin 1 (TRPA1) cation channel mRNA expression. Here, we hypothesized that alcohol and its metabolites, that pass through the blood-brain barrier, may influence the function of urocortinergic cells in centrally projecting EWcp by activating TRPA1 ion channels. We aimed to examine the functional activity of TRPA1 in centrally projecting EWcp and its possible role in a mouse model of acute alcohol exposure. Methods: Electrophysiological measurements were performed on acute brain slices of C57BL/6J male mice containing the centrally projecting EWcp to prove the functional activity of TRPA1 using a selective, potent, covalent agonist JT010. Male TRPA1 knockout (KO) and wildtype (WT) mice were compared with each other in the morphological studies upon acute alcohol treatment. In both genotypes, half of the animals was treated intraperitoneally with 1g/kg 6% ethanol vs. physiological saline-injected controls. Transcardial perfusion was performed 2h after the treatment. In the centrally projecting EWcp area, FOS immunohistochemistry was performed to assess neuronal activation. TRPA1, CART, and urocortin 1 mRNA expression as well as urocortin 1 and CART peptide content was semi-quantified by RNAscope in situ hybridization combined with immunofluorescence. Results: JT010 activated TRPA1 channels of the urocortinergic cells in acute brain slices. Alcohol treatment resulted in a significant FOS activation in both genotypes. Alcohol decreased the Trpa1 mRNA expression in WT mice. The assessment of urocortin 1 peptide immunoreactivity revealed lower basal urocortin 1 in KO mice compared to WTs. The urocortin 1 peptide content was affected genotype-dependently by alcohol: the peptide content decreased in WTs while it increased in KO mice. Alcohol exposure influenced neither CART and urocortin 1 mRNA expression nor the centrally projecting EWcp/CART peptide content. Conclusion: We proved the presence of functional TRPA1 receptors on urocortin 1 neurons of the centrally projecting EWcp. Decreased Trpa1 mRNA expression upon acute alcohol treatment, associated with reduced neuronal urocortin 1 peptide content suggesting that this cation channel may contribute to the regulation of the urocortin 1 release.

Noxious chemical discrimination by Tribolium castaneum TRPA1 channel in the HEK293 cell expression system

Nociception is the sensory perception of noxious chemical stimuli. Repellent behavior to avoid noxious stimuli is indispensable for survival, and this mechanism has been evolutionarily conserved across a wide range of species, from mammals to insects. The transient receptor potential ankyrin 1 (TRPA1) channel is one of the most conserved noxious chemical sensors. Here, we describe the heterologous stable expression of Tribolium castaneum TRPA1 (TcTRPA1) in human embryonic kidney (HEK293) cells. The intracellular Ca2+ influx was measured when two compounds, citronellal and l-menthol, derived from plant essential oils, were applied in vitro using a fluorescence assay. The analysis revealed that citronellal evoked Ca2+ influx dose-dependently for TcTRPA1, whereas l-menthol did not. In combination with our present and previous results of the avoidance-behavioral assay at the organism level, we suggest that TcTRPA1 discriminates between these two toxic compounds, and diversification in the chemical nociception selectivity has occurred in TRPA1 channel among insect taxa.

TRPA1 participation in behavioral impairment induced by chronic corticosterone administration.

Major depressive disorder (MDD) is one of the most diagnosed mental disorders. Despite this, its pathophysiology remains poorly understood. In this context, basic research aims to unravel the pathophysiological mechanisms of MDD as well as investigate new targets and substances with therapeutic potential. Transient receptor potential ankyrin 1 (TRPA1) is a transmembrane channel considered a sensor for inflammation and oxidative stress. Importantly, both inflammation and oxidative stress have been suggested as participants in the pathophysiology of MDD. However, the potential participation of TRPA1 in depressive disorder remains poorly investigated. To investigate the involvement of the TRPA1 channel in the behavioral changes induced by chronic corticosterone administration (CCA) in male mice. Swiss male mice were exposed to 21days of CCA protocol and then treated with HC-030031 or A-967079, TRPA1 antagonists. Behavioral tests, analyzes of oxidative parameters and TRPA1 immunocontent were performed in the prefrontal cortex (PFC) and hippocampus (HIP). CCA induced despair-like behavior in mice accompanied by an increase in the levels of hydrogen peroxide (H2O2), a TRPA1 agonist, which was reversed by TRPA1 antagonists and ketamine (positive control). In addition, CCA protocol reduced the immunocontent of this channel in the HIP and showeda tendency to increase the TRPA1 protein expression in the PFC. Our work suggests that TRPA1 channel appears crucial to mediate the behavioral impairment induced by CCA in male Swiss mice.

The role of TRPA1 channels in thermosensation.

Transient receptor potential ankyrin 1 (TRPA1) is a polymodal nonselective cation channel sensitive to different physical and chemical stimuli. TRPA1 is associated with many important physiological functions in different species and thus is involved in different degrees of evolution. TRPA1 acts as a polymodal receptor for the perceiving of irritating chemicals, cold, heat, and mechanical sensations in various animal species. Numerous studies have supported many functions of TRPA1, but its temperature-sensing function remains controversial. Although TRPA1 is widely distributed in both invertebrates and vertebrates, and plays a crucial role in tempreture sensing, the role of TRPA1 thermosensation and molecular temperature sensitivity are species-specific. In this review, we summarize the temperature-sensing role of TRPA1 orthologues in terms of molecular, cellular, and behavioural levels.

Modulation of Glia Activation by TRPA1 Antagonism in Preclinical Models of Migraine.

Preclinical data point to the contribution of transient receptor potential ankyrin 1 (TRPA1) channels to the complex mechanisms underlying migraine pain. TRPA1 channels are expressed in primary sensory neurons, as well as in glial cells, and they can be activated/sensitized by inflammatory mediators. The aim of this study was to investigate the relationship between TRPA1 channels and glial activation in the modulation of trigeminal hyperalgesia in preclinical models of migraine based on acute and chronic nitroglycerin challenges. Rats were treated with ADM_12 (TRPA1 antagonist) and then underwent an orofacial formalin test to assess trigeminal hyperalgesia. mRNA levels of pro- and anti-inflammatory cytokines, calcitonin gene-related peptide (CGRP) and glia cell activation were evaluated in the Medulla oblongata and in the trigeminal ganglia. In the nitroglycerin-treated rats, ADM_12 showed an antihyperalgesic effect in both acute and chronic models, and it counteracted the changes in CGRP and cytokine gene expression. In the acute nitroglycerin model, ADM_12 reduced nitroglycerin-induced increase in microglial and astroglial activation in trigeminal nucleus caudalis area. In the chronic model, we detected a nitroglycerin-induced activation of satellite glial cells in the trigeminal ganglia that was inhibited by ADM_12. These findings show that TRPA1 antagonism reverts experimentally induced hyperalgesia in acute and chronic models of migraine and prevents multiple changes in inflammatory pathways by modulating glial activation.

An Inhibitory Function of TRPA1 Channels in TGF-β1-driven Fibroblast-to-Myofibroblast Differentiation.

TRPA1 (transient receptor potential ankyrin 1) is a nonselective Ca2+-permeable cation channel, which was originally cloned from human lung fibroblasts (HLFs). TRPA1-mediated Ca2+ entry is evoked by exposure to several chemicals, including allyl isothiocyanate (AITC), and a protective effect of TRPA1 activation in the development of cardiac fibrosis has been proposed. Yet the function of TRPA1 in TGF-β1 (transforming growth factor-β1)-driven fibroblast-to-myofibroblast differentiation and the development of pulmonary fibrosis remains elusive. TRPA1 expression and function were analyzed in cultured primary HLFs, and mRNA concentrations were significantly reduced after adding TGF-β1. Expression of genes encoding fibrosis markers (e.g., ACTA2, SERPINE1 [plasminogen activator inhibitor 1], FN1 [fibronectin], COL1A1 [type I collagen]) was increased after siRNA-mediated downregulation of TRPA1 mRNA in HLFs. Moreover, AITC-induced Ca2+ entry in HLFs was decreased after TGF-β1 treatment and by application of TRPA1 siRNAs, while AITC treatment alone did not reduce cell viability or enhance apoptosis. Most interestingly, AITC-induced TRPA1 activation augmented ERK1/2 (extracellular signal-regulated kinase 1/2) and SMAD2 linker phosphorylation, which might inhibit TGF-β-receptor signaling. Our results suggest an inhibitory function of TRPA1 channels in TGF-β1-driven fibroblast-to-myofibroblast differentiation. Therefore, activation of TRPA1 channels might be protective during the development of pulmonary fibrosis in patients.

Paclitaxel Regulates TRPA1 Function and Expression Through PKA and PKC

Paclitaxel (PTX) is a frequently used anticancer drug that causes peripheral neuropathy. Transient receptor potential ankyrin 1 (TRPA1), a plasma membrane calcium channel, has been associated with PTX toxicity and with other chemotherapy agents such as oxaliplatin and vincristine. However, the effect of PTX on the functional expression and calcium currents of TRPA1 has not been determined. The present study shows the effect of PTX on TRPA1 activity in a neuronal cell line (SH-SY5Y). The effect of PTX on the expression of TRPA1 was assessed through quantitative PCR and Western blot analyses to determine the relative mRNA and protein expression levels. To assess the effect on calcium flux and currents, cells were exposed to PTX; simultaneously, a specific agonist and antagonist of TRPA1 were added to evaluate the differential response in exposed versus control cells. To assess the effect of PKA, PKC and PI3K on PTX-induced TRPA1 increased activity, selective inhibitors were added to these previous experiments. PTX increased the mRNA and protein expression of TRPA1 as well as the TRPA1-mediated Ca2+ currents and intracellular Ca2+ concentrations. This effect was dependent on AITC (a selective specific agonist) and was abolished with HC-030031 (a selective specific antagonist). The inhibition of PKA and PKC reduced the effect of PTX on the functional expression of TRPA1, whereas the inhibition of PI3K had no effects. PTX-induced neuropathy involves TRPA1 activity through an increase in functional expression and is regulated by PKA and PKC signaling. These findings support the role of the TRPA1 channel in the mechanisms altered by PTX, which can be involved in the process that lead to chemotherapy-induced neuropathy.

Modulatory effect of pomegranate extract on TRPA1, TRPM2 and caspase-3 expressions in colorectal cancer induction of mice

Abstract Objectives This study aimed to evaluate the effects of pomegranate fruit extract (PFE) on levels of transient receptor potential (TRP) channel and caspase-3 (Casp-3) expressions, tumor necrosis factor-α (TNF-α), total sialic acid (TSA), reduced glutathione (GSH), and malondialdehyde (MDA) in mice with induced colorectal cancer (CRC) by investigating effects of PFE on in vitro mitotic index (MI). Methods Different PFE concentrations on​​ MI against 0.3 μg/mL mitomycin-C (MMC) in cell culture were evaluated by binocular light microscopy. During in vivo applications on Balb/c mice, it was given once physiological saline to group I, PFE for ten weeks to group II, a single dose of azoxymethane (AOM) plus dextran sulfate sodium in drinking water (DSS) to group III, and AOM plus DSS plus PFE to group IV. Tissue samples were evaluated by western blotting, spectrophotometric, and histopathological methods. Results Expressions of Casp-3, TRP ankyrin 1 (TRPA1), and melastatin 2 (TRPM2) channels and TNF-α, TSA, GSH, and MDA concentrations in evaluated tissues had significantly better levels in PFE-treated groups compared to CRC-induced mice. Conclusions Results of the present study indicate that PFE application in mice with induced CRC may be an important modulator of TRPA1 and TRPM2 channels, apoptosis, and inflammatory response by decreasing oxidative stress.

TRPA1 modulation by Sigma-1 receptor prevents oxaliplatin-induced painful peripheral neuropathy.

Chemotherapy-induced peripheral neuropathy is a frequent, disabling side effect of anticancer drugs. Oxaliplatin, a platinum compound used in the treatment of advanced colorectal cancer, often leads to a form of chemotherapy-induced peripheral neuropathy characterized by mechanical and cold hypersensitivity. Current therapies for chemotherapy-induced peripheral neuropathy are ineffective, often leading to the cessation of treatment. Transient receptor potential ankyrin 1 (TRPA1) is a polymodal, non-selective cation-permeable channel expressed in nociceptors, activated by physical stimuli and cellular stress products. TRPA1 has been linked to the establishment of chemotherapy-induced peripheral neuropathy and other painful neuropathic conditions. Sigma-1 receptor is an endoplasmic reticulum chaperone known to modulate the function of many ion channels and receptors. Sigma-1 receptor antagonist, a highly selective antagonist of Sigma-1 receptor, has shown effectiveness in a phase II clinical trial for oxaliplatin chemotherapy-induced peripheral neuropathy. However, the mechanisms involved in the beneficial effects of Sigma-1 receptor antagonist are little understood. We combined biochemical and biophysical (i.e. intermolecular Förster resonance energy transfer) techniques to demonstrate the interaction between Sigma-1 receptor and human TRPA1. Pharmacological antagonism of Sigma-1R impaired the formation of this molecular complex and the trafficking of functional TRPA1 to the plasma membrane. Using patch-clamp electrophysiological recordings we found that antagonists of Sigma-1 receptor, including Sigma-1 receptor antagonist, exert a marked inhibition on plasma membrane expression and function of human TRPA1 channels. In TRPA1-expressing mouse sensory neurons, Sigma-1 receptor antagonists reduced inward currents and the firing of actions potentials in response to TRPA1 agonists. Finally, in a mouse experimental model of oxaliplatin neuropathy, systemic treatment with a Sigma-1 receptor antagonists prevented the development of painful symptoms by a mechanism involving TRPA1. In summary, the modulation of TRPA1 channels by Sigma-1 receptor antagonists suggests a new strategy for the prevention and treatment of chemotherapy-induced peripheral neuropathy and could inform the development of novel therapeutics for neuropathic pain.

2-hydroxyethyl methacrylate-derived reactive oxygen species stimulate ATP release via TRPA1 in human dental pulp cells

Extracellular ATP (adenosine triphosphate) and transient receptor potential ankyrin 1 (TRPA1) channels are involved in calcium signaling in odontoblasts and dental pain. The resin monomer 2-hydroxyethyl methacrylate (HEMA), used in dental restorative procedures, is related to apoptotic cell death via oxidative stress. Although the TRPA1 channel is highly sensitive to reactive oxygen species (ROS), the effect of HEMA-induced ROS on ATP release to the extracellular space and the TRPA1 channel has not been clarified in human dental pulp. In this study, we investigated the extracellular ATP signaling and TRPA1 activation by HEMA-derived ROS in immortalized human dental pulp cells (hDPSC-K4DT). Among the ROS-sensitive TRP channels, TRPA1 expression was highest in undifferentiated hDPSC-K4DT cells, and its expression levels were further enhanced by osteogenic differentiation. In differentiated hDPSC-K4DT cells, 30 mM HEMA increased intracellular ROS production and ATP release, although 3 mM HEMA had no effect. Pretreatment with the free radical scavenger PBN (N-tert-butyl-α-phenylnitrone) or TRPA1 antagonist HC-030031 suppressed HEMA-induced responses. These results suggest that ROS production induced by a higher dose of HEMA activates the TRPA1 channel in human dental pulp cells, leading to ATP release. These findings may contribute to the understanding of the molecular and cellular pathogenesis of tertiary dentin formation and pain in response to dental biomaterials.

Transient receptor potential Ankyrin 1: structure, function and ligands

Introduction: Transient receptor potential ankyrin 1 (TRPA1) is a protein expressed in many living organisms. During the study of TRPA1, its unique biological role as a universal and polymodal sensor of various altering agents was found. The aim of this study is to search and generalize information about structural features and molecular determinants, mechanisms of activation, action and modulation of TRPA1 as a universal pain and inflammation sensor, as well as the nature of activators and antagonists of this target and their therapeutic potential.
 Materials and methods: This article presents an overview of the results of scientific research of TRPA1, its modulators, as well as an overview of their pharmacological potential over the period from the discovery of these channels to the present, with an emphasis on the last decade.
 Results and discussion: The main collected data on expression, structural features and molecular determinants, mecha­nisms of activation and action of TRPA1 indicate its role as a universal and labile element of the primary response of the body to adverse exogenous and endogenous factors. Regardless of the nature of the stimulus, hyperstimulation of TRPA1 channels can lead to such phenomena as pain, inflammation, itching, edema and other manifestations of alteration, and therefore TRPA1 blockade can be used in the treatment of various diseases accompanied by these pathological conditions. Currently, TRPA1 antagonists are being actively searched for and studied, as evidenced by a high patent activity over the past 14 years; however, the molecular mechanisms of action and pharmacological properties of TRPA1 blockers remain understudied.
 Conclusion: Acquire of new information about TRPA1 will help in the development of its modulators, which can be­come promising analgesics, anti-inflammatory drugs, bronchodilators, and agents for the treatment of cardiovascular diseases of new generations.

Identification of Ligands for Chicken Transient Receptor Potential Ankyrin 1 Channel and Chemosensory Perception of Herbal Compounds in Chickens.

The pungency induced by spices and herbs plays an important role in food choice and appetite, and it is suggested that adding spices and herbs to feed as natural alternatives to antibiotics has beneficial effects in poultry farming. However, our knowledge of the chemosensory perception of herbal compounds in chickens is limited. Transient receptor potential ankyrin 1 (TRPA1) is involved in the sensory perception of various herbal compounds. Here, we performed calcium imaging and electrophysiological analyses using cells transiently expressing chicken TRPA1 (cTRPA1) and identified two novel cTRPA1 ligands—eugenol and thymol. In a behavioral assay, chickens responded to cTRPA1 ligands, including eugenol, thymol, cinnamaldehyde, carvacrol, and allyl isothiocyanate. These results provide evidence that chickens have a functional TRPA1 channel and chemosensory perception of various herbal compounds.