The transient receptor potential ion channel TRPA1 is a Ca2+-permeable nonselective cation channel widely expressed in sensory neurons, but also in many nonneuronal tissues typically possessing barrier functions, such as the skin, joint synoviocytes, cornea, and the respiratory and intestinal tracts. Here, the primary role of TRPA1 is to detect potential danger stimuli that may threaten the tissue homeostasis and the health of the organism. The ability to directly recognize signals of different modalities, including chemical irritants, extreme temperatures, or osmotic changes resides in the characteristic properties of the ion channel protein complex. Recent advances in cryo-electron microscopy have provided an important framework for understanding the molecular basis of TRPA1 function and have suggested novel directions in the search for its pharmacological regulation. This chapter summarizes the current knowledge of human TRPA1 from a structural and functional perspective and discusses the complex allosteric mechanisms of activation and modulation that play important roles under physiological or pathophysiological conditions. In this context, major challenges for future research on TRPA1 are outlined.
- MeSH
- alosterická regulace MeSH
- elektronová kryomikroskopie metody MeSH
- kationtové kanály TRP metabolismus chemie fyziologie MeSH
- kationtový kanál TRPA1 * metabolismus chemie fyziologie MeSH
- lidé MeSH
- vztahy mezi strukturou a aktivitou MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
TRP channels sense temperatures ranging from noxious cold to noxious heat. Whether specialized TRP thermosensor modules exist and how they control channel pore gating is unknown. We studied purified human TRPA1 (hTRPA1) truncated proteins to gain insight into the temperature gating of hTRPA1. In patch-clamp bilayer recordings, ∆1-688 hTRPA1, without the N-terminal ankyrin repeat domain (N-ARD), was more sensitive to cold and heat, whereas ∆1-854 hTRPA1, also lacking the S1-S4 voltage sensing-like domain (VSLD), gained sensitivity to cold but lost its heat sensitivity. In hTRPA1 intrinsic tryptophan fluorescence studies, cold and heat evoked rearrangement of VSLD and the C-terminus domain distal to the transmembrane pore domain S5-S6 (CTD). In whole-cell electrophysiology experiments, replacement of the CTD located cysteines 1021 and 1025 with alanine modulated hTRPA1 cold responses. It is proposed that hTRPA1 CTD harbors cold and heat sensitive domains allosterically coupled to the S5-S6 pore region and the VSLD, respectively.
- MeSH
- alanin MeSH
- ankyrinová repetice * MeSH
- kationtový kanál TRPA1 genetika metabolismus MeSH
- lidé MeSH
- tryptofan MeSH
- vnímání teploty MeSH
- vysoká teplota * MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The Transient Receptor Potential Ankyrin 1 (TRPA1) channel is an integrative molecular sensor for detecting environmental irritant compounds, endogenous proalgesic and inflammatory agents, pressure, and temperature. Different post-translational modifications participate in the discrimination of the essential functions of TRPA1 in its physiological environment, but the underlying structural bases are poorly understood. Here, we explored the role of the cytosolic N-terminal residue Ser602 located near a functionally important allosteric coupling domain as a potential target of phosphorylation. The phosphomimetic mutation S602D completely abrogated channel activation, whereas the phosphonull mutations S602G and S602N produced a fully functional channel. Using mutagenesis, electrophysiology, and molecular simulations, we investigated the possible structural impact of a modification (mutation or phosphorylation) of Ser602 and found that this residue represents an important regulatory site through which the intracellular signaling cascades may act to reversibly restrict or "dampen" the conformational space of the TRPA1 channel and promote its transitions to the closed state.
- MeSH
- fosforylace MeSH
- HEK293 buňky MeSH
- kationtový kanál TRPA1 chemie genetika metabolismus MeSH
- konformace proteinů MeSH
- lidé MeSH
- molekulární modely MeSH
- mutace * MeSH
- proteinové domény MeSH
- serin metabolismus MeSH
- simulace molekulární dynamiky MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Transient receptor potential ankyrin 1 channel (TRPA1) serves as a key sensor for reactive electrophilic compounds across all species. Its sensitivity to temperature, however, differs among species, a variability that has been attributed to an evolutionary divergence. Mouse TRPA1 was implicated in noxious cold detection but was later also identified as one of the prime noxious heat sensors. Moreover, human TRPA1, originally considered to be temperature-insensitive, turned out to act as an intrinsic bidirectional thermosensor that is capable of sensing both cold and heat. Using electrophysiology and modeling, we compare the properties of human and mouse TRPA1, and we demonstrate that both orthologues are activated by heat, and their kinetically distinct components of voltage-dependent gating are differentially modulated by heat and cold. Furthermore, we show that both orthologues can be strongly activated by cold after the concurrent application of voltage and heat. We propose an allosteric mechanism that could account for the variability in TRPA1 temperature responsiveness.
- MeSH
- biologické modely MeSH
- druhová specificita MeSH
- elektrofyziologie metody MeSH
- HEK293 buňky MeSH
- kationtový kanál TRPA1 metabolismus MeSH
- lidé MeSH
- myši MeSH
- napětím ovládané aniontové kanály metabolismus fyziologie MeSH
- nízká teplota MeSH
- sekvence aminokyselin MeSH
- vysoká teplota MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Bortezomib (BTZ) is used as a chemotherapeutic agent for the treatment of multiple myeloma. Nevertheless, one of the significant limiting complications of BTZ is painful peripheral neuropathy during BTZ therapy. Thus, in this study we examined signaling pathways of interleukin-6 (IL-6) and transient receptor potential ankyrin 1 (TRPA1) in the sensory nerves responsible for neuropathic pain induced by BTZ and further determined if influencing the pathways can improve neuropathic pain. ELISA and western blot analysis were used to examine the levels of IL-6, and IL-6 receptor (IL-6R), TRPA1 and p38-MAPK and JNK signal in the lumbar dorsal root ganglion. Behavioral test was performed to determine mechanical and cold sensitivity in a rat model. Our results showed that systemic injection of BTZ increased mechanical pain and cold sensitivity as compared with control animals. Data also showed that protein expression of TRPA1 and IL-6R was upregulated in the dorsal root ganglion of BTZ rats and blocking TRPA1 attenuated mechanical and cold sensitivity in control rats and BTZ rats. Notably, the inhibitory effect of blocking TRPA1 was smaller in BTZ rats than that in control rats. In addition, a blockade of IL-6 signal attenuated intracellular p38-MAPK and JNK in the sensory neuron. This also decreased TRPA1 expression and alleviated mechanical hyperalgesia and cold hypersensitivity in BTZ rats. In conclusion, we revealed specific signaling pathways leading to neuropathic pain induced by chemotherapeutic BTZ, including IL-6-TRPA1, suggesting that blocking these signals is beneficial to alleviate neuropathic pain during BTZ intervention.
- MeSH
- acetanilidy farmakologie MeSH
- analgetika farmakologie MeSH
- bortezomib * MeSH
- chinoxaliny farmakologie MeSH
- fosforylace MeSH
- inhibitory proteasomu * MeSH
- interleukin-6 antagonisté a inhibitory metabolismus MeSH
- JNK mitogenem aktivované proteinkinasy metabolismus MeSH
- kationtový kanál TRPA1 antagonisté a inhibitory metabolismus MeSH
- mitogenem aktivované proteinkinasy p38 metabolismus MeSH
- modely nemocí na zvířatech MeSH
- nervové receptory metabolismus účinky léků MeSH
- neuralgie chemicky indukované farmakoterapie metabolismus patofyziologie MeSH
- potkani Sprague-Dawley MeSH
- práh bolesti účinky léků MeSH
- puriny farmakologie MeSH
- pyraziny farmakologie MeSH
- receptory interleukinu-6 antagonisté a inhibitory metabolismus účinky léků MeSH
- signální transdukce MeSH
- spinální ganglia metabolismus patofyziologie účinky léků MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Exposure to repetitive low-frequency electromagnetic field (LF-EMF) shows promise as a non-invasive approach to treat various sensory and neurological disorders. Despite considerable progress in the development of modern stimulation devices, there is a limited understanding of the mechanisms underlying their biological effects and potential targets at the cellular level. A significant impact of electromagnetic field on voltage-gated calcium channels and downstream signalling pathways has been convincingly demonstrated in many distinct cell types. However, evidence for clear effects on primary sensory neurons that particularly may be responsible for the analgesic actions of LF-EMF is still lacking. Here, we used F11 cells derived from dorsal root ganglia neurons as an in vitro model of peripheral sensory neurons and three different protocols of high-induction magnetic stimulation to determine the effects on chemical responsiveness and spontaneous activity. We show that short-term (<180 sec.) exposure of F11 cells to LF-EMF reduces calcium transients in response to bradykinin, a potent pain-producing inflammatory agent formed at sites of injury. Moreover, we characterize an immediate and reversible potentiating effect of LF-EMF on neuronal spontaneous activity. Our results provide new evidence that electromagnetic field may directly modulate the activity of sensory neurons and highlight the potential of sensory neuron-derived cell line as a tool for studying the underlying mechanisms at the cellular and molecular level.
Human transient receptor potential ankyrin channel 1 (TRPA1) is a polymodal sensor implicated in pain, inflammation and itching. An important locus for TRPA1 regulation is the cytoplasmic N-terminal domain, through which various exogenous electrophilic compounds such as allyl-isothiocyanate from mustard oil or cinnamaldehyde from cinnamon activate primary afferent nociceptors. This major region is comprised of a tandem set of 17 ankyrin repeats (AR1-AR17), five of them contain a strictly conserved T/SPLH tetrapeptide motif, a hallmark of an important and evolutionarily conserved contribution to conformational stability. Here, we characterize the functional consequences of putatively stabilizing and destabilizing mutations in these important structural units and identify AR2, AR6, and AR11-13 to be distinctly involved in the allosteric activation of TRPA1 by chemical irritants, cytoplasmic calcium, and membrane voltage. Considering the potential involvement of the T/SP motifs as putative phosphorylation sites, we also show that proline-directed Ser/Thr kinase CDK5 modulates the activity of TRPA1, and that T673 outside the AR-domain is its only possible target. Our data suggest that the most strictly conserved N-terminal ARs define the energetics of the TRPA1 channel gate and contribute to chemical-, calcium- and voltage-dependence.
- MeSH
- alosterická regulace MeSH
- ankyrinová repetice MeSH
- cyklin-dependentní kinasa 5 genetika metabolismus MeSH
- gating iontového kanálu účinky léků genetika MeSH
- HEK293 buňky MeSH
- kationtový kanál TRPA1 genetika metabolismus MeSH
- lidé MeSH
- mutace MeSH
- oligopeptidy chemie farmakologie MeSH
- proteinové domény MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
