Receptor Potential Research Articles

Topical neurokinin-1 receptor antagonism ameliorates ocular pain and prevents corneal nerve degeneration in an animal model of dry eye disease.

Ocular pain is a common complaint to eye care providers, associated with a variety of ocular conditions, among which dry eye disease (DED) is affecting millions of people worldwide. Despite being highly prevalent, ocular pain is not managed adequately in the clinic. The aim of this study was to investigate the analgesic potential of neurokinin-1 receptor (NK1R) antagonism in DED. Dry eye disease was induced in mice, and an NK1R antagonist L-733,060 was topically administered twice daily throughout the study for 14 days. Hyperalgesia and allodynia were assessed using the eye-wiping test and palpebral ratio measurements. Corneas were collected for measuring substance P (SP) levels by enzyme-linked immunosorbent assay (ELISA) and imaging nerves by immunostaining. Trigeminal ganglions (TG) were collected to determine SP levels by ELISA and transient receptor potential cation channel subfamily V member 1 (TRPV1), transient receptor potential cation channelsubfamily M (melastatin) member 8, c-Fos, and activating transcription factor 3 (ATF3) mRNA levels by real-time polymerase chain reaction. Treating DED mice with L-733,060 resulted in a significant reduction in eye wipe behavior, a significant increase in palpebral ratio, and significant decreases in SP levels in both the cornea and TG compared with the vehicle-treated group. In addition, NK1R antagonist treatment significantly suppressed the upregulation of TRPV1, ATF3, and c-Fos and prevented corneal nerve loss. Neurokinin-1 receptor antagonism effectively reduced ocular nociception, decreased neuronal activation, and preserved corneal nerves in mice with DED. These findings suggest that blockade of SP signaling pathway is a promising therapeutic strategy for managing DED pain.

TRPM2 deficiency ameliorated H9N2 influenza virus-induced acute lung injury in mice

Oxidative stress is involved in lung damage induced by the influenza virus. The transient receptor potential melastatin-2 (TRPM2) cation channel, a Ca2+ permeable non-selective cation channel, is implicated in the mediation of multiple tissue injuries induced by oxidative stress. The role of TRPM2 in several diseases has been widely studied, but there have been few studies on the involvement of TRPM2 in lung injury induced by the H9N2 influenza virus. We investigated the effects of TRPM2 on pathological alterations, oxidative stress, apoptosis, and inflammation in mice infected with H9N2 virus. TRPM2 knockout (TRPM2-/-) mice and wild-type (WT) mice were infected separately with H9N2 influenza virus. Pulmonary oedema, lung permeability, Ca2+ concentration, redox imbalance, apoptosis, and levels of inflammatory factors (IL-1β, IL-6, TNF-α) were increased in WT mice infected with H9N2 virus. However, these effects were diminished by TRPM2 knockout. Our results emphasised the significance of TRPM2 knockdown in mitigating pathological lung alterations, maintaining Ca2+ homeostasis, reducing oxidative damage, preventing apoptosis, and suppressing the production of inflammatory cytokines in H9N2 virus-infected mice. Therefore, inhibition of TRPM2 activation is a potentially important therapeutic strategy for treating lung injury.

Evaluation of immunohistochemical TRPC3 and TRPC6 expression patterns in human endometriosis.

Although to date the pathogenesis of endometriosis remains largely unexplained, it is known that processes of migration, proliferation and revascularization and thus calcium as a messenger substance play an important role. Consecutively, the present study examines the immunohistochemical expression of the calcium transient receptor potential channels 3 and 6 (TRPC3 and TRPC6) in ectopically located (outside the uterine cavity) endometrial tissue. Laparoscopically collected and histomorphologically verified endometriosis tissues from several different intraabdominal locations were examined (n = 20) and immunohistochemical stainings were performed with anti-TRPC3 and anti-TRPC6 antibodies (Alomone Labs, Jerusalem). Hereby, eutopic endometrium served as a healthy control cohort (n = 6). Staining patterns were evaluated using a modified immunoreactive score (IRS) and exploratory statistical analysis was performed, aiming to determine relations of staining intensities with associated clinical parameters such as rASRM stage and location. We determined a strong cytoplasmatic TRPC3 and TRPC6 expression in all ectopic endometrial glandular formations, albeit with focally varying staining intensities. Within our cohort, we did not verify a statistically significant difference of TRPC3 and TRPC6 expression between endometriosis patients and a healthy control group or between different clinical affections (rASRM stages). Our study confirms - to our knowledge for the first time - the successful immunohistochemical assessment of TRPC3 and TRPC6 in endometriosis, setting the basis for future studies aiming at evaluating not only clinical aspects of TRPC3 and TRPC6 expression but also shedding light on its function in the pathophysiological context of endometriosis.

Anatomical mapping of neural lineages expressing the transient receptor potential vanilloid type 1 receptor using a modified and combined PACT and CUBIC protocol for rapid tissue clearance.

Tissue clearance is a rapidly evolving technology that allows for the three-dimensional imaging of intact biological tissues. Preexisting tissue-clearing techniques, such as Passive Clarity Technique (PACT) and Clear Unobstructed Brain Imaging Cocktails and Computational Analysis (CUBIC), clear tissues adequately but have distinct disadvantages, such as taking extensive time to clear tissues and degradation of endogenous tissue fluorescence. We developed a new tissue-clearing technique combining PACT and CUBIC protocols to map the neural lineages expressing the transient receptor potential vanilloid type 1 (TRPV1) receptor. To test the effectiveness of this modified protocol, a TdTomato reporter mouse line was crossed with a separate mouse line containing Cre recombinase under the control of the TRPV1 promoter, which would result in TRPV1 cell lineages expressing green fluorescence protein (GFP). Compared to the PACT protocol that requires several weeks to months for tissue clearance, our approach reached a satisfactory clearance within 3 days in all neural tissues as well as several non-neural tissues such as colon, duodenum, and pancreas. Compared to the CUBIC approach, all tissues reserved strong GFP fluorescence. Robust GFP fluorescence was visualized in sensory neuronal soma but not in sympathetic ganglia neuronal soma. On the other hand, GFP fluorescence in the TRPV1 cells appeared to be expressed throughout the epithelium of the duodenum and colon and the arteriole smooth muscle in all non-neuronal tissues. This study shows that our combined PACT and CUBIC (CPC) protocol can clear tissues in significantly less time while preserving tissue integrity and fluorescence.

Mechanisms of Low Temperature-Induced Growth Hormone Resistance via TRPA1 Channel Activation in Male Nile Tilapia.

Low temperatures significantly impact growth in ectothermic vertebrates, though the underlying mechanisms remain poorly understood. This study investigates the role of transient receptor potential ankyrin 1 (TRPA1) channels in mediating low temperature effects on growth performance and growth hormone (GH) resistance in Nile tilapia (Oreochromis niloticus). Prolonged exposure to low temperature (16°C for 35 days) impaired growth performance and induced GH resistance, characterized by elevated serum GH levels and decreased insulin-like growth factor-1 (IGF-1) levels. Molecular analysis revealed tissue-specific upregulation of TRPA1 expression in the pituitary and liver under low-temperature conditions, concurrent with alterations in GH/IGF-1 axis-related gene expression. Pharmacological modulation of TRPA1 using an agonist mimicked low temperature effects on the GH/IGF-1 axis, while an antagonist reversed cold-induced hormonal changes. In vitro experiments with tilapia hepatocytes demonstrated that TRPA1 activation decreased IGF-1 expression through Ca2+/calmodulin-dependent pathways and disrupted GH-induced JAK2/STAT5 signaling. Additionally, TRPA1 activation induced GH receptor degradation primarily through lysosomal pathways, with partial involvement of proteasomal mechanisms. This study is the first to reveal that TRPA1 channels play a crucial role in mediating the effects of low temperature on GH resistance in fish, providing new insights into temperature regulation of endocrine function. The evolutionary conservation of TRPA1 and the GH/IGF-1 axis suggests potential relevance to stress-induced endocrine dysfunction in other vertebrates, including mammals.

ROS-regulated SUR1-TRPM4 drives persistent activation of NLRP3 inflammasome in microglia after whole-brain radiation

Delayed radiation-induced brain injury (RIBI) characterized by progressive cognitive decline significantly impacts patient outcomes after radiotherapy. The activation of NLRP3 inflammasome within microglia after brain radiation is involved in the progression of RIBI by mediating inflammatory responses. We have previously shown that sulfonylurea receptor 1-transient receptor potential M4 (SUR1-TRPM4) mediates microglial NLRP3-related inflammation following global brain ischemia. However, the role of SUR1-TRPM4 in RIBI remains unclear. Here, we found that whole-brain radiation induced up-regulation and assembly of SUR1-TRPM4, which further activated the NLRP3 inflammasome in microglia and caused persistent neuroinflammation in mice. Blocking SUR1-TRPM4 by glibenclamide or gene deletion of Trpm4 effectively prevented NLRP3-mediated neuroinflammation and alleviated RIBI. Utilizing the mouse model of RIBI and irradiated BV2 cells, we further demonstrated that irradiation caused mitochondrial damage to microglia, leading to violent release of reactive oxygen species (ROS), which enhanced the transcription of SUR1, TRPM4, and NLRP3 inflammasome-related molecules. Moreover, ROS up-regulated ten-eleven translocation 2 (TET2) to enhance TRPM4 expression by mediating the demethylation of the gene promoter, thereby facilitating the assembly of SUR1-TRPM4 in microglia. In summary, this study deciphers that SUR1-TRPM4 crucially mediates the persistent activation of microglial NLRP3 inflammasome under the action of ROS after whole-brain radiation, offering novel therapeutic strategies for delayed RIBI as well as other NLRP3-related neurological disorders involving excessive ROS production.

Erlotinib therapy for Olmsted syndrome with p.L655P missense mutation in the TRPV3 gene: a case report

Olmsted syndrome (OS) is a rare disorder characterized by a mutilating palmoplantar keratoderma and periorificial keratotic plaques, but which shows considerable clinical heterogeneity. Recently, transient receptor potential vanilloid 3 (TRPV3) mutations associated with autosomal dominant or recessive OS have been reported. Here we describe a classically OS case with definitive diagnosis of OS based on clinical features and a genetic assay. Genetic analysis revealed heterozygous variants in the TRPV3 gene using whole-exome sequencing of case-parents’ trios. This mutation was not identified in his mother. Notably, a previously unreported heterozygous frameshift mutation, c.1964 T > C (p.L655P), was identified in exon 15 of the TRPV3 gene in this patient and his father. Additionally, the patient was effectively managed with oral erlotinib at a daily dose of 75 mg. After 3 months of treatment, most plantar lesions resolved, and the pain experienced was mildly alleviated. No significant adverse effects were observed in this case during treatment. In addition, we review the OS literature regarding TRPV3 gene mutations.

Neuron Modulation by Synergetic Management of Redox Status and Oxidative Stress.

The transient receptor potential (TRP) channel is a key sensor for diverse cellular stimuli, regulating the excitability of primary nociceptive neurons. Sensitization of the TRP channel can heighten pain sensitivity to innocuous or mildly noxious stimuli. Here, reversible modulation of TRP channels is achieved by controlling both the light-induced photoelectrochemical reaction to induce neuronal depolarization, and antioxidants for neuronal protection. It is based on a hybrid nanosystem, CZPN, created by coating CeO2 nanocrystals with the metalloporphyrin ZnTPyP. Light irradiation triggers an electrochemical response, with efficient electron injection from ZnTPyP to CeO2, converting Ce4+ into Ce3+ as antioxidants. Meanwhile, the charge migrates from surrounding O2 molecules to the hole-injected ZnTPyP*, giving rise to reactive oxygen species (ROS). This change in the redox environment sensitizes TRP channels, eliciting action potentials in primary rat neurons, and is partially blocked by pretreatment with capsazepine. The resulting CeO2-x, with a high Ce3+/Ce4+ ratio, can scavenge excessive ROS to prevent oxidative damage. The light-induced pain behaviors in mice pre-injected with CZPN are further confirmed. This work suggests a safe, effective, and universal approach to photoelectrochemical processes for modulation and research of the peripheral nervous system.

Enhancing Photodynamic Therapy Efficacy via Photo-Triggered Calcium Overload and Oxygen Delivery in Tumor Hypoxia Management.

Background: Photodynamic therapy (PDT) has emerged as a promising treatment for cancer, primarily due to its ability to generate reactive oxygen species (ROS) that directly induce tumor cell death. However, the hypoxic microenvironment commonly found within tumors poses a significant challenge by inhibiting ROS production. This study aims to investigate the effect of improving tumor hypoxia on enhancing PDT. Result: We employed polylactic-co-glycolic acid (PLGA) as a delivery vector for the encapsulation of indocyanine green (ICG), a photosensitizer, and perfluorohexane (PFH), with surface labeling mannose to facilitate targeted delivery. A potential therapeutic nanoplatform was fabricated, designated as Man-PFH-ICG@PLGA. These nanospheres are capable of localizing at tumor sites and can be tracked using photoacoustic (PA) imaging. Upon laser irradiation, the ROS generated by PDT activated the transient receptor potential cation channel subfamily A member 1 (TRPA1) located on the cell membrane. This activation led to an influx of extracellular Ca2+ and subsequently resulted in calcium overload. The excessive Ca2+ selectively accumulated in mitochondria, disrupting the function of enzymes involved in the mitochondrial respiratory chain. This disruption inhibits cellular respiration and decreases oxygen consumption in tumor cells, ultimately contributing to the alleviation of the hypoxic microenvironment within tumors. Simultaneously, PFH exhibited a high affinity for oxygen and can deliver exogenous oxygen directly to the tumor site through simple diffusion along the concentration gradient. Both the direct and indirect mechanisms synergistically contribute to ameliorating the hypoxic conditions within tumors, thereby augmenting the efficacy of PDT. Conclusions: The synergistic effect of photocontrolled calcium overload from endogenous sources and the oxygen-carrying nanoplatform alleviates tumor hypoxia, thereby enhancing the efficacy of PDT. This approach provides a new perspective on PDT.

Beyond Dopamine: Novel Therapeutic Pathways for Parkinson's Disease Through Receptor Signaling.

Parkinson's disease (PD) is a progressive neurological condition characterized by both dopaminergic and non-dopaminergic brain cell loss. Patients with Parkinson's disease have tremors as a result of both motor and non-motor symptoms developing. Idiopathic Parkinson's disease (idiopathic PD) prevalence is increasing in people over 60. The medication L-dopa, which is now on the market, merely relieves symptoms and has several negative effects. In this article, we highlight the therapeutic potential of glucagon-like peptide-1, adenosine A2A, and cannabinoid receptors as attractive targets for enhancing neuroprotection and reducing a variety of motor and non-motor symptoms. Recent research has widened knowledge of new therapeutic targets and detailed cellular mechanisms, providing invaluable insights into the essential roles of cannabinoid receptors, adenosine A2A receptors, and glucagon-like peptide-1 receptors in PD pathogenesis and unique opportunities for drug development for mankind globally.

Ononin's Antagonistic Activity towards TRPV1: Insights from Molecular Dynamics and Capsaicin-Evoked Calcium Response in DRG Neurons.

The search for effective painkillers has led to intensive research, with a particular focus on the transient receptor potential vanilloid-1 (TRPV1) channel as a possible target. One promising candidate is ononin, which is investigated for its binding with TRPV1 through a 200-ns molecular dynamic simulation and analysed via root-meansquare deviation (RMSD), root-mean-square fluctuation (RMSF), hydrogen-bond interactions, radius of gyration (RadGyr), and MM-PBSA energy calculations. The results were further validated experimentally via calcium imaging studies. Molecular dynamics revealed that the ononin-TRPV1 complex achieved stable binding within a remarkably short time of approximately 38 ns while maintaining the degree of compactness of the receptor throughout a 200 ns simulation period. In contrast, the capsazepine-TRPV1 complex displayed more significant structural deviations during the whole simulation. Moreover, MM-PBSA energy calculations showed a relatively strong binding affinity between ononin and TRPV1, mainly attributed to favourable hydrophobic interactions. Pre-incubation of dorsal root ganglia (DRG) neurons with ononin (1 and 10 μM) or capsazepine (10 μM) for 4 min prior to stimulation with capsaicin significantly reduced capsaicin-evoked calcium responses. No significant difference between capsazepine and ononin was found at a concentration of 10 μM. Overall, this research demonstrates the potential of ononin as a potential antagonist for developing analgesics targeting TRPV1. Hence, and to our best knowledge, this study represents the first report of ononin's antagonistic activity towards TRPV1.

Chikungunya Particle and RNA Induce Mechanical and Heat Hypersensitivities in a TRPV1-Dependent Manner

Chikungunya virus (CHIKV), the causative agent of the chikungunya fever, is an alphavirus widely transmitted by the bite of the female mosquito of the genus Aedes sp., especially in tropical and subtropical regions. Brazil is the country most affected by the microorganism. CHIKV classically induces articular pain, which can become long lasting for even years in a great number of the infected individuals, reducing their quality of life. The mechanisms of CHIKV-induced pain are poorly understood, but recent evidence indicated a role for the transient receptor potential vanilloid 1 (TRPV1) in this pathology. Herein, we assessed the ability of intra-articularly injected inactivated CHIKV or its RNA to trigger nociception in mice. Both stimuli induced bilateral secondary hyperalgesia to mechanical and heat stimuli. These responses were attenuated by TRPV1 ablation or antagonism. Joint structural alterations and increased cartilage TRPV1 protein expression were detected in the ipsilateral knee joints injected with either CHIKV or viral RNA. However, the lack of this receptor did not influence the histological changes triggered by CHIKV or RNA. The results further support the role of TRPV1 in CHIKV-induced pain and highlight its importance in the chronic phase of the disease.

Characterisation of periorbital mechanical allodynia in the reserpine-induced fibromyalgia model in mice: The role of the Schwann cell TRPA1/NOX1 signalling pathway.

Fibromyalgia (FM) is a complex and multifaceted condition characterized by a range of clinical symptoms, including widespread pain and a strong association with migraine headaches. Recent findings have underscored the role of oxidative stress and transient receptor potential ankyrin 1 (TRPA1) channel in migraine and FM. However, the precise mechanisms underlying the comorbidity between migraine and FM are unclear. Periorbital mechanical allodynia (PMA), which recapitulates one of the major symptoms of migraine, and the feed-forward mechanism driven by reactive oxygen species and TRPA1, were investigated in a reserpine-induced FM model in C57BL/6J mice, employing pharmacological interventions and genetic approaches. Reserpine-treated mice developed PMA (which was alleviated by antimigraine drugs) and increased endoneurial macrophages and oxidative stress markers in the trigeminal nerve tissues (neuroinflammation). These responses were absent upon macrophage depletion and by pharmacological inhibition or global genetic deletion of the TRPA1 channel. Furthermore, selective silencing of TRPA1 in Schwann cells attenuated both reserpine-induced PMA and neuroinflammation, while selective silencing of TRPA1 in sensory neurons reduced PMA but not neuroinflammation. In reserpine-treated mice, Schwann cell TRPA1 promoted NADPH oxidase 1-mediated reactive oxygen species generation and macrophage increase in the mouse trigeminal nerve, which sustains PMA. Targeting TRPA1 channels in Schwann cells could offer a novel therapeutic strategy for FM-related headaches.

Sex and age effects on chronic inflammatory pain development, maintenance, and resolution in Wistar rats.

Millions of Americans live with chronic inflammatory pain conditions, and the prevalence of these conditions increases with age and is higher in females. Still, it is poorly understood how sex, age and peripheral gene expression affect the trajectory of chronic inflammatory pain conditions. We used the inflammatory agent, Complete Freund's Adjuvant (CFA), to systematically test sex and age effects on mechanical and thermal sensitivity in adolescent and adult male and female Wistar rats over 3 weeks (Experiment 1 [onset]) or 11 weeks (Experiment 2 [recovery]). We report that relative to male CFA rats, CFA females are mechanically hypersensitive at all time points and thermally hypersensitive at later time points (long-term during maintenance and recovery). Also, within CFA rats, more adult males (90%) achieved behavioral recovery at 11 weeks, relative to adolescent males (70%), adult females (70%) and adolescent females (50%). Behavioral recovery was most highly correlated with thermal nociception scores in most groups. Among adult males, significant positive correlations were seen between mechanical and thermal nociception scores and between scores in the CFA-injected and non-injected paws. In paw tissue from a subset of rats from experiment 2, we also report increased transient receptor potential cation channel subfamily V member 1 (TRPV1) gene expression in adult CFA but not adolescent CFA rats, and increased pro- and anti-inflammatory, and triglyceride synthesis-related gene expression in all CFA rats. Our results demonstrate apparent sex and age differences in the trajectory of chronic inflammatory pain-related behavior and gene expression in the affected paw of rats. PERSPECTIVE: This article highlights sex and age differences in the trajectory of chronic inflammatory pain and possible peripheral mechanisms driving recovery in Wistar rats. This data could be used to better understand recovery patterns in patients with this type of pain and provides a starting point for assessment of novel treatments.

Identification of a binding site for small molecule inhibitors targeting human TRPM4

Transient receptor potential (TRP) melastatin 4 (TRPM4) protein is a calcium-activated monovalent cation channel associated with various genetic and cardiovascular disorders. The anthranilic acid derivative NBA is a potent and specific TRPM4 inhibitor, but its binding site in TRPM4 has been unknown, although this information is crucial for drug development targeting TRPM4. We determine three cryo-EM structures of full-length human TRPM4 embedded in native lipid nanodiscs without inhibitor, bound to NBA, and an anthranilic acid derivative, IBA. We found that the small molecules NBA and IBA were bound in a pocket formed between the S3, S4, and TRP helices and the S4-S5 linker of TRPM4. Our structural data and results from patch clamp experiments enable validation of a binding site for small molecule inhibitors, paving the way for further drug development targeting TRPM4.

Role of neurogenic inflammation in intervertebral disc degeneration.

In healthy intervertebral discs (IVDs), nerves and blood vessels are present only in the outer annulus fibrosus, while in degenerative IVDs, a large amount of nerve and blood vessel tissue grows inward. Evidence supports that neurogenic inflammation produced by neuropeptides such as substance P and calcitonin gene related peptide released by the nociceptive nerve fibers innervating the IVDs plays a crucial role in the process of IVD degeneration. Recently, non-neuronal cells, including IVD cells and infiltrating immune cells, have emerged as important players in neurogenic inflammation. IVD cells and infiltrating immune cells express functional receptors for neuropeptides through which they receive signals from the nervous system. In return, IVD cells and immune cells produce neuropeptides and nerve growth factor, which stimulate nerve fibers. This communication generates a positive bidirectional feedback loop that can enhance the inflammatory response of the IVD. Recently emerging transient receptor potential channels have been recognized as contributors to neurogenic inflammation in the degenerative IVDs. These findings suggest that neurogenic inflammation involves complex pathophysiological interactions between sensory nerves and multiple cell types in the degenerative IVDs. Clarifying the mechanism of neurogenic inflammation in IVD degeneration may provide in-depth understanding of the pathology of discogenic low back pain.

TRPV4 as a Novel Regulator of Ferroptosis in Colon Adenocarcinoma: Implications for Prognosis and Therapeutic Targeting.

Colon adenocarcinoma (COAD) is a leading cause of cancer-related mortality worldwide. Transient receptor potential vanilloid 4 (TRPV4), a calcium-permeable non-selective cation channel, has been implicated in various cancers, including COAD. This study investigates the role of TRPV4 in colon adenocarcinoma and elucidates its potential mechanism via the ferroptosis pathway. Gene expression profiles and clinical data were obtained from The Cancer Genome Atlas (TCGA), encompassing 647 colon adenocarcinoma tissue samples and 51 normal colorectal tissue samples. Ferroptosis-related genes were retrieved from the FerrDb database. Differential expression analysis, survival analysis, and Cox proportional hazards regression were performed to assess the prognostic significance of TRPV4. Protein-protein interaction networks and gene enrichment analyses (GO and KEGG) were conducted to explore functional associations. In vitro experiments were carried out using HT-29 and SW480 colon cancer cell lines. TRPV4 was knocked down using siRNA, and cell viability was assessed via hematoxylin and eosin (HE) staining. Immunofluorescence assays evaluated the expression of ferroptosis-related proteins (SLC3A2, GPX4) and proliferation markers (KI67, SRC, CTNNB1, COL1). TRPV4 expression was significantly elevated in colon adenocarcinoma tissues compared to normal tissues (p < 0.05), demonstrating high diagnostic accuracy (AUC = 0.848). High TRPV4 expression correlated with poorer overall survival (OS) and disease-specific survival (DSS), particularly in patients over 65years old and those in clinical stage II. Cox regression analysis confirmed TRPV4 as an independent prognostic factor (HR = 1.395, p = 0.074). Bioinformatics analyses revealed that TRPV4 is closely associated with ferroptosis-related genes, participating in key biological processes such as responses to external stimuli, oxidative stress, and cell adhesion. In vitro, TRPV4 knockdown significantly reduced cell viability (p < 0.05) and decreased expression levels of SLC3A2, GPX4, KI67, SRC, and COL1 (p < 0.05). The addition of the ferroptosis inhibitor FER-1 did not restore cell viability in TRPV4 knockdown cells, suggesting that TRPV4 modulates cell survival through the ferroptosis pathway. The bioinformation and in vitro experiments inTRPV4 and ferroptosis-related genes support the hypothesis that TRPV4 influences tumor cell survival via the ferroptosis pathway. The inability of FER-1 to rescue viability in TRPV4-deficient cells further confirms this mechanism. These findings provide novel insights into the molecular mechanisms of COAD and highlight TRPV4 as a potential therapeutic target. TRPV4 is significantly upregulated in COAD and is associated with unfavorable patient outcomes. It appears to promote tumor progression by regulating the ferroptosis pathway, affecting the expression of key ferroptosis-related genes and proliferation markers. Targeting TRPV4 may offer a new therapeutic approach for COAD, and further research is warranted to explore its role in other cancers and to develop TRPV4-based therapies.

Targeting TRPC channels for control of arthritis-induced bone erosion.

Arthritis leads to bone erosion due to an imbalance between osteoclast and osteoblast function. Our prior investigations revealed that the Ca2+-selective ion channel, Orai1, is critical for osteoclast maturation. Here, we show that the small-molecule ELP-004 preferentially inhibits transient receptor potential canonical (TRPC) channels. While ELP-004 minimally affected physiological RANKL-induced osteoclast maturation in murine bone marrow- and spleen-derived myeloid cells (BMSMCs) and human PBMC-derived cells, it potently interfered with osteoclast maturation driven by TNFα or LTB4. The contribution of TRPC channels to osteoclastogenesis was examined using BMSMCs derived from TRPC4-/- or TRPC(1-7)-/- mice, again revealing preferential interference with osteoclastogenesis driven by proinflammatory cytokines. ELP-004 also reduced bone erosion in a mouse model of rheumatoid arthritis. These investigations reveal TRPC channels as critical mediators of inflammatory bone erosion and provide insight into the major target of ELP-004, a drug currently in preclinical testing as a therapeutic for inflammatory arthritis.

A nanoparticle-based wireless deep brain stimulation system that reverses Parkinson's disease.

Deep brain stimulation technology enables the neural modulation with precise spatial control but requires permanent implantation of conduits. Here, we describe a photothermal wireless deep brain stimulation nanosystem capable of eliminating α-synuclein aggregates and restoring degenerated dopamine neurons in the substantia nigra to treat Parkinson's disease. This nanosystem (ATB NPs) consists of gold nanoshell, an antibody against the heat-sensitive transient receptor potential vanilloid family member 1 (TRPV1), and β-synuclein (β-syn) peptides with a near infrared-responsive linker. ATB NPs by stereotactic injection target dopamine neurons expressing TRPV1 receptors in the substantia nigra. Upon pulsed near-infrared irradiation, ATB NPs, serving as nanoantennae, convert the light into heat, leading to calcium ion influx, depolarization, and action potentials in dopamine neurons through TRPV1 receptors. Simultaneously, β-synuclein peptides released from ATB NPs cooperate with chaperone-mediated autophagy initiated by heat shock protein, HSC70, to effectively eliminate α-synuclein fibrils in neurons. These orchestrated actions restored pathological dopamine neurons and locomotor behaviors of Parkinson's disease.

Histone Methyltransferase G9a in Primary Sensory Neurons Promotes Inflammatory Pain and Transcription of Trpa1 and Trpv1 via Bivalent Histone Modifications.

Transient receptor potential ankyrin 1 (TRPA1) and vanilloid 1 (TRPV1) channels are crucial for detecting and transmitting nociceptive stimuli. Inflammatory pain is associated with sustained increases in TRPA1 and TRPV1 expression in primary sensory neurons. However, the epigenetic mechanisms driving this upregulation remain unknown. G9a (encoded by Ehmt2) catalyzes H3K9me2 and generally represses gene transcription. In this study, we found that intrathecal administration of UNC0638, a specific G9a inhibitor, or G9a-specific siRNA, substantially reduced complete Freund's adjuvant (CFA)-induced pain hypersensitivity. Remarkably, CFA treatment did not induce persistent pain hypersensitivity in male and female mice with conditional Ehmt2 knockout in dorsal root ganglion (DRG) neurons. RNA sequencing and quantitative PCR analyses showed that CFA treatment caused a sustained increase in mRNA levels of Trpa1 and Trpv1 in the DRG. Ehmt2 knockout in DRG neurons elevated baseline Trpa1 and Trpv1 mRNA levels but notably reversed CFA-induced increases in their expression. Chromatin immunoprecipitation revealed that CFA treatment reduced G9a and H3K9me2 levels while increasing H3K9ac and H3K4me3-activating histone marks-at Trpa1 and Trpv1 promoters in the DRG. Strikingly, conditional Ehmt2 knockout in DRG neurons not only diminished H3K9me2 but also reversed CFA-induced increases in H3K9ac and H3K4me3 at Trpa1 and Trpv1 promoters. Our findings suggest that G9a in primary sensory neurons constitutively represses Trpa1 and Trpv1 transcription under normal conditions but paradoxically enhances their transcription during tissue inflammation. This latter action accounts for inflammation-induced TRPA1 and TRPV1 upregulation in the DRG. Thus, G9a could be targeted for alleviating persistent inflammatory pain.Significance statement This study demonstrates for the first time that G9a, a histone methyltransferase, in sensory neurons is crucial for the persistent pain development following inflammation. Inhibiting or knockdown of G9a at the spinal cord level reduced inflammation-induced pain hypersensitivity. Remarkably, mice lacking G9a in sensory neurons failed to develop persistent pain hypersensitivity after inflammation. Ablating G9a in sensory neurons increased baseline expression of the TRPA1 and TRPV1 ion channels but reversed their upregulation induced by inflammation. Additionally, G9a deletion blocked the inflammation-driven enrichment of activating histone marks at Trpa1 and Trpv1 promoters. These findings highlight a dual role of G9a in sensory neurons: suppressing Trpa1 and Trpv1 transcription under normal conditions while promoting their transcription during inflammation through bivalent histone modifications.