Receptor Potential Cation Channel Subfamily Research Articles

An Overview of the Effects of Tenapanor on Visceral Hypersensitivity in the Treatment of Irritable Bowel Syndrome with Constipation.

Patients with irritable bowel syndrome with constipation (IBS-C) experience persistent abdominal pain, a common symptom leading to greater healthcare utilization and reports of treatment non-response. Clinically significant improvements in abdominal pain were observed in clinical trials of tenapanor, a first-in-class inhibitor of sodium/hydrogen exchanger isoform 3 (NHE3), for the treatment of IBS-C in adults. This narrative review reports the current knowledge about visceral hypersensitivity as a mechanism for abdominal pain in patients with IBS-C and explores the published evidence for hypothesized mechanisms by which tenapanor may reduce visceral hypersensitivity leading to the observed clinical response of decreased abdominal pain. Abdominal pain is experienced through activation and signaling of nociceptive dorsal root ganglia that innervate the gut. These sensory afferent neurons may become hypersensitized through signaling of transient receptor potential cation channel subfamily V member 1 (TRPV1), resulting in reduced action potential thresholds. TRPV1 signaling is also a key component of the proinflammatory cascade involving mast cell responses to macromolecule exposure following permeation through the intestinal epithelium. Indirect evidence of this pathway is supported by observations of higher pain in association with increased intestinal permeability in patients with IBS. Tenapanor reduces intestinal sodium absorption, leading to increased water retention in the intestinal lumen, thereby improving gastrointestinal motility. In animal models of visceral hypersensitivity, tenapanor normalized visceromotor responses and normalized TRPV1-mediated nociceptive signaling. By improving gastrointestinal motility, decreasing intestinal permeability and inflammation, and normalizing nociception through decreased TRPV1 signaling, tenapanor may reduce visceral hypersensitivity, leading to less abdominal pain in patients with IBS-C. Therapies that have demonstrated effects on visceral hypersensitivity may be the future direction for meaningful abdominal pain relief for patients with IBS-C.

Distinct induction pathways of heat shock protein 27 in human keratinocytes: Heat stimulation or capsaicin through phosphorylation of heat shock factor 1 at serine 326 and/or suppression of ΔNp63

Epidermal keratinocytes, forming the outermost layer of the human body, serve as a crucial barrier against diverse external stressors such as ultraviolet radiation. Proper keratinocyte differentiation and effective responses to external stimuli are pivotal for maintaining barrier integrity. Heat is one such stimulus that triggers the synthesis of heat shock proteins (HSPs) when cells are exposed to temperatures above 42 °C. Additionally, activation of the transient receptor potential cation channel subfamily V member 1 (TRPV1) occurs at 42 °C. Here, we explore the interplay between TRPV1 signaling and HSP induction in human keratinocytes. Both heat and capsaicin, a TRPV1 agonist, induce expression of HSP27, HSP70, and HSP90 in keratinocytes. Interestingly, pharmacological inhibition of TRPV1 attenuates heat-induced HSP27 expression, but not that of HSP70 or HSP90. Furthermore, both heat and capsaicin stimulation result in distinct phosphorylation patterns of heat shock factor 1 (HSF1), with phosphorylation at serine 326 being a common feature. Notably, genetic manipulation to mimic dephosphorylation of HSF1 at serine 326 reduces HSP27 levels. Additionally, ΔNp63, a key regulator of epidermal differentiation, negatively modulates HSP27 expression independently of HSF1 phosphorylation status. While heat stimulation has no effect on ΔNp63 expression, capsaicin reduces its levels. The precise role of TRPV1 signaling in keratinocytes warrants further investigation for a comprehensive understanding of its impact on barrier function.

Abstract 2922: Sensory innervation as a novel driver of ovarian cancer progression

Abstract One of the main challenges currently faced in ovarian cancer treatment is that the primary platinum/taxane therapy used to treat patients does not meaningfully extend survival. The overall survival for ovarian cancer patients with advanced disease is less than 30% with most patients recurring within 5 years of initial therapy. Once resistant disease develops there are few second line therapy options, which inevitably leads to disease progression. Thus, there is a critical need to identify new therapies that can overcome ovarian cancer chemoresistance and produce meaningful increases in patient survival. In recent years, new efforts have focused on targeting the tumor microenvironment (TME), the complex mixture of non-cancer cells that surround and support the cancer cells within the tumor. Different strategies have evolved to target the TME, such as immune checkpoint inhibitors or angiogenesis inhibitors. However, these TME targeting therapies have limited effect when used to treat ovarian cancer patients. Most ovarian tumors have a microenvironment that is highly immunosuppressive and do not respond or are resistant to angiogenesis inhibitors. Thus, new TME targeting therapies must be developed that can induce a therapeutic effect in ovarian tumors and can be used to treat most ovarian cancer patients. A novel TME component ripe for therapeutic targeting are the nerve fibers that infiltrate tumors in a process termed tumor innervation. Recent studies in several cancers have shown that tumor innervation can promote tumor growth/metastasis. However, in ovarian cancer the role of innervation in promoting cancer progression remains undefined. Here we show that Transient Receptor Potential cation channel subfamily V member 1 (TRPV1)+ sensory innervation plays a significant role in driving ovarian cancer growth and metastasis. Analysis of patient samples shows that sensory nerve fiber innervation is much higher in ovarian tumors vs benign reproductive tissue. In addition, ablation of TRPV1 sensory nerve fibers in vivo causes reduced tumor burden and prolongs survival in a syngeneic mouse model of ovarian cancer metastasis. Taken together, our results establish TRPV1+ sensory innervation as a novel driver of ovarian cancer growth/metastasis and a potential therapeutic target for ovarian cancer treatment. Citation Format: Matthew Knarr, Katherine Cummins, Dusan Racordon, Hunter Reavis, Timothy Lippert, Ryan Hausler, Priyanka Rawat, Suyeon Ryu, Jamie Moon, Dave Hoon, Roger Greenberg, Paola Vermeer, Ronny Drapkin. Sensory innervation as a novel driver of ovarian cancer progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2922.

Mechanosensitive TRPV4 channel guides maturation and organization of the bilayered mammary epithelium

Biophysical cues from the cell microenvironment are detected by mechanosensitive components at the cell surface. Such machineries convert physical information into biochemical signaling cascades within cells, subsequently leading to various cellular responses in a stimulus-dependent manner. At the surface of extracellular environment and cell cytoplasm exist several ion channel families that are activated by mechanical signals to direct intracellular events. One of such channel is formed by transient receptor potential cation channel subfamily V member, TRPV4 that is known to act as a mechanosensor in wide variaty of tissues and control ion-influx in a spatio-temporal way. Here we report that TRPV4 is prominently expressed in the stem/progenitor cell populations of the mammary epithelium and seems important for the lineage-specific differentiation, consequently affecting mechanical features of the mature mammary epithelium. This was evident by the lack of several markers for mature myoepithelial and luminal epithelial cells in TRPV4-depleted cell lines. Interestingly, TRPV4 expression is controlled in a tension-dependent manner and it also impacts differentation process dependently on the stiffness of the microenvironment. Furthermore, such cells in a 3D compartment were disabled to maintain normal mammosphere structures and displayed abnormal lumen formation, size of the structures and disrupted cellular junctions. Mechanosensitive TRPV4 channel therefore act as critical player in the homeostasis of normal mammary epithelium through sensing the physical environment and guiding accordingly differentiation and structural organization of the bilayered mammary epithelium.

Puerarin attenuates remifentanil‑induced postoperative hyperalgesia via targeting PAX6 to regulate the transcription of TRPV1.

Remifentanil‑induced hyperalgesia (RIH) is characterized by the emergence of stimulation‑induced pain, including phenomena such as allodynia and thermal hyperalgesia following remifentanil infusion. As a sequence‑specific DNA binding transcription factor, PAX6 positively and negatively regulates transcription and is expressed in multiple cell types in the developing and adult central nervous system. It was hypothesized that puerarin could relieve RIH via targeting PAX6 to regulate transcription of transient receptor potential cation channel subfamily V Member 1 (TRPV1). A total of 32 rats were randomly divided into five groups, namely control group, RI group, RI + 10 mg/kg puerarin group (RI + puerarin10), RI + 20 mg/kg puerarin group (RI + puerarin20), and RI + 40 mg/kg puerarin group (RI + puerarin40). Mechanical and thermal hyperalgesia were tested at ‑24, 2, 6, 24 and 48 h after remifentanil infusion. Following the sacrifice of rats after the last behavioral test, western blot was used to detect the expression levels of TRPV1 in the tissues; Immunofluorescence staining and western blotting were used to detect the expression of PAX6 in the spinal cord. PharmMapper and JASPAR were used to predict the binding sites of puerarin/PAX6/TRPV1. Chromatin immunoprecipitation‑PCR and dual luciferase reporter assay were used to verify the targeting relationship between PAX6 and TRPV1. Immunofluorescence was used to detect the expression levels of TRPV1 and p‑NR2B. The results revealed that puerarin (10, 20, 40 mg/kg) dose‑dependently reduced thermal and mechanical hyperalgesia from 2 to 48 h after remifentanil infusion. Remifentanil infusion remarkably stimulated the expression of phosphorylated (p‑)NR2B. Nevertheless, the increased amount of p‑NR2B by RIH was dose‑dependently suppressed by puerarin in rats. In conclusion, puerarin was revealed to attenuate postoperative RIH via targeting PAX6 to regulate the transcription of TRPV1.

Discovering single cannabidiol or synergistic antitumor effects of cannabidiol and cytokine-induced killer cells on non-small cell lung cancer cells.

A multitude of findings from cell cultures and animal studies are available to support the anti-cancer properties of cannabidiol (CBD). Since CBD acts on multiple molecular targets, its clinical adaptation, especially in combination with cancer immunotherapy regimen remains a serious concern. Considering this, we extensively studied the effect of CBD on the cytokine-induced killer (CIK) cell immunotherapy approach using multiple non-small cell lung cancer (NSCLC) cells harboring diverse genotypes. Our analysis showed that, a) The Transient Receptor Potential Cation Channel Subfamily V Member 2 (TRPV2) channel was intracellularly expressed both in NSCLC cells and CIK cells. b) A synergistic effect of CIK combined with CBD, resulted in a significant increase in tumor lysis and Interferon gamma (IFN-g) production. c) CBD had a preference to elevate the CD25+CD69+ population and the CD62L_CD45RA+terminal effector memory (EMRA) population in NKT-CIK cells, suggesting early-stage activation and effector memory differentiation in CD3+CD56+ CIK cells. Of interest, we observed that CBD enhanced the calcium influx, which was mediated by the TRPV2 channel and elevated phosphor-Extracellular signal-Regulated Kinase (p-ERK) expression directly in CIK cells, whereas ERK selective inhibitor FR180204 inhibited the increasing cytotoxic CIK ability induced by CBD. Further examinations revealed that CBD induced DNA double-strand breaks via upregulation of histone H2AX phosphorylation in NSCLC cells and the migration and invasion ability of NSCLC cells suppressed by CBD were rescued using the TRPV2 antagonist (Tranilast) in the absence of CIK cells. We further investigated the epigenetic effects of this synergy and found that adding CBD to CIK cells decreased the Long Interspersed Nuclear Element-1 (LINE-1) mRNA expression and the global DNA methylation level in NSCLC cells carrying KRAS mutation. We further investigated the epigenetic effects of this synergy and found that adding CBD to CIK cells decreased the Long Interspersed Nuclear Element-1 (LINE-1) mRNA expression and the global DNA methylation level in NSCLC cells carrying KRAS mutation. Taken together, CBD holds a great potential for treating NSCLC with CIK cell immunotherapy. In addition, we utilized NSCLC with different driver mutations to investigate the efficacy of CBD. Our findings might provide evidence for CBD-personized treatment with NSCLC patients.

TRPV4 Activator-Containing CMT-Hy Hydrogel Enhances Bone Tissue Regeneration In Vivo by Enhancing Mitochondrial Health.

Treating different types of bone defects is difficult, complicated, time-consuming, and expensive. Here, we demonstrate that transient receptor potential cation channel subfamily V member 4 (TRPV4), a mechanosensitive, thermogated, and nonselective cation channel, is endogenously present in the mesenchymal stem cells (MSCs). TRPV4 regulates both cytosolic Ca2+ levels and mitochondrial health. Accordingly, the hydrogel made from a natural modified biopolymer carboxymethyl tamarind CMT-Hy and encapsulated with TRPV4-modulatory agents affects different parameters of MSCs, such as cell morphology, focal adhesion points, intracellular Ca2+, and reactive oxygen species- and NO-levels. TRPV4 also regulates cell differentiation and biomineralization in vitro. We demonstrate that 4α-10-CMT-Hy and 4α-50-CMT-Hy (the hydrogel encapsulated with 4αPDD, 10 and 50 nM, TRPV4 activator) surfaces upregulate mitochondrial health, i.e., an increase in ATP- and cardiolipin-levels, and improve the mitochondrial membrane potential. The same scaffold turned out to be nontoxic in vivo. 4α-50-CMT-Hy enhances the repair of the bone-drill hole in rat femur, both qualitatively and quantitatively in vivo. We conclude that 4α-50-CMT-Hy as a scaffold is suitable for treating large-scale bone defects at low cost and can be tested for clinical trials.

Stem Leydig cells support macrophage immunological homeostasis through mitochondrial transfer in mice

As testicular mesenchymal stromal cells, stem Leydig cells (SLCs) show great promise in the treatment of male hypogonadism. The therapeutic functions of mesenchymal stromal cells are largely determined by their reciprocal regulation by immune responses. However, the immunoregulatory properties of SLCs remain unclear. Here, we observe that SLCs transplantation restore male fertility and testosterone production in an ischemia‒reperfusion injury mouse model. SLCs prevent inflammatory cascades through mitochondrial transfer to macrophages. Reactive oxygen species (ROS) released from activated macrophages inducing mitochondrial transfer from SLCs to macrophages in a transient receptor potential cation channel subfamily member 7 (TRPM7)-mediated manner. Notably, knockdown of TRPM7 in transplanted SLCs compromised therapeutic outcomes in both testicular ischemia‒reperfusion and testicular aging mouse models. These findings reveal a new mechanism of SLCs transplantation that may contribute to preserve testis function in male patients with hypogonadism related to immune disorders.

Effect of heat stress on the hypothalamic expression profile of water homeostasis-associated genes in low- and high-water efficient chicken lines.

With climate change, selection for water efficiency and heat resilience are vitally important. We undertook this study to determine the effect of chronic cyclic heat stress (HS) on the hypothalamic expression profile of water homeostasis-associated markers in high (HWE)- and low (LWE)-water efficient chicken lines. HS significantly elevated core body temperatures of both lines. However, the amplitude was higher by 0.5-1°C in HWE compared to their LWE counterparts. HWE line drank significantly less water than LWE during both thermoneutral (TN) and HS conditions, and HS increased water intake in both lines with pronounced magnitude in LWE birds. HWE had better feed conversion ratio (FCR), water conversion ratio (WCR), and water to feed intake ratio. At the molecular level, the overall hypothalamic expression of aquaporins (AQP8 and AQP12), arginine vasopressin (AVP) and its related receptor AVP2R, angiotensinogen (AGT), angiotensin II receptor type 1 (AT1), and calbindin 2 (CALB2) were significantly lower; however, CALB1 mRNA and AQP2 protein levels were higher in HWE compared to LWE line. Compared to TN conditions, HS exposure significantly increased mRNA abundances of AQPs (8,12), AVPR1a, natriuretic peptide A (NPPA), angiotensin I-converting enzyme (ACE), CALB1 and 2, and transient receptor potential cation channel subfamily V member 1 and 4 (TRPV1 and TRPV4) as well as the protein levels of AQP2, however it decreased that of AQP4 gene expression. A significant line by environment interaction was observed in several hypothalamic genes. Heat stress significantly upregulated AQP2 and SCT at mRNA levels and AQP1 and AQP3 at both mRNA and protein levels, but it downregulated that of AQP4 protein only in LWE birds. In HWE broilers, however, HS upregulated the hypothalamic expression of renin (REN) and AVPR1b genes and AQP5 proteins, but it downregulated that of AQP3 protein. The hypothalamic expression of AQP (5, 7, 10, and 11) genes was increased by HS in both chicken lines. In summary, this is the first report showing improvement of growth performances in HWE birds. The hypothalamic expression of several genes was affected in a line- and/or environment-dependent manner, revealing potential molecular signatures for water efficiency and/or heat tolerance in chickens.

A Short-Term Zinc-Deficient Diet Maintains Serum Calcium Concentrations through Ca Absorption-Related Gene Expression in Rats.

We investigated the effects of short-term dietary zinc deficiency on zinc and calcium metabolism. Four-week-old male Wistar rats were divided into two pair-fed groups for a 1-wk treatment: zinc-deficient group (ZD, 1 ppm); control group (PF, 30 ppm). The mRNA expression of zinc transporters, such as Slc39a (Zip) 4, Zip5, Zip10, and Slc30a (ZnT) 1, in various tissues (liver, kidney, and duodenum) quickly responded to dietary zinc deficiency. Although there was no significant difference in serum calcium concentrations between the PF and ZD groups, serum 1,25-dihydroxycholecalciferol (1,25(OH)2D3) was higher in the ZD group than in the PF group. Moreover, short-term zinc deficiency significantly increased mRNA expression of transient receptor potential (TRP) cation channel subfamily vanilloid (V) member 6, S100 calcium binding protein G (S100g), and ATPase plasma membrane Ca2+ transporting 1 (Atp2b1) in the duodenum. Furthermore, short-term zinc deficiency increased vitamin D receptor (VDR) and cytochrome P450 family 24 subfamily A member 1 (Cyp24a1) mRNA expression in the kidney. These findings suggested that short-term zinc deficiency maintains serum calcium concentrations through Ca absorption-related gene expression in the duodenum, and that short-term zinc deficiency induced the expression of Cyp24a1 in kidney in response to an increase in the serum 1,25(OH)2D3 level.

ATF4 inhibits TRPV4 function and controls itch perception in rodents and nonhuman primates.

Acute and chronic itch are prevalent and incapacitating, yet the neural mechanisms underlying both acute and chronic itch are just starting to be unraveled. Activated transcription factor 4 (ATF4) belongs to the ATF/CREB transcription factor family and primarily participates in the regulation of gene transcription. Our previous study has demonstrated that ATF4 is expressed in sensory neurons. Nevertheless, the role of ATF4 in itch sensation remains poorly understood. Here, we demonstrate that ATF4 plays a significant role in regulating itch sensation. The absence of ATF4 in dorsal root ganglion (DRG) neurons enhances the itch sensitivity of mice. Overexpression of ATF4 in sensory neurons significantly alleviates the acute and chronic pruritus in mice. Furthermore, ATF4 interacts with the transient receptor potential cation channel subfamily V member 4 (TRPV4) and inhibits its function without altering the expression or membrane trafficking of TRPV4 in sensory neurons. In addition, interference with ATF4 increases the itch sensitivity in nonhuman primates and enhances TRPV4 currents in nonhuman primates DRG neurons; ATF4 and TRPV4 also co-expresses in human sensory neurons. Our data demonstrate that ATF4 controls pruritus by regulating TRPV4 signaling through a nontranscriptional mechanism and identifies a potential new strategy for the treatment of pathological pruritus.

Müller cells under hydrostatic pressure modulate retinal cell survival via TRPV1/PLCγ1 complex-mediated calcium influx in experimental glaucoma.

Glaucoma, an irreversible blinding eye disease, is currently unclear whose pathological mechanism is. This study investigated how transient receptor potential cation channel subfamily V member 1 (TRPV1), 1-phosphatidylinositol 4,5-bisphosphate phosphodiesterase gamma-1 (PLCγ1), and P2X purinoceptor 7 (P2X7) modulate the levels of intracellular calcium ions (Ca2+ ) and adenosine triphosphate (ATP) in Müller cells and retinal ganglion cells (RGCs) under conditions of elevated intraocular pressure (IOP). Müller cells were maintained at hydrostatic pressure (HP). TRPV1- and PLCG1-silenced Müller cells and P2X7-silenced RGCs were constructed by transfection with short interfering RNA (siRNAs). RGCs were cultured with the conditioned media of Müller cells under HP. A mouse model of chronic ocular hypertension (COH) was established and used to investigate the role of TRPV1 in RGCs in vivo. Müller cells and RGCs were analyzed by ATP release assays, intracellular calcium assays, CCK-8 assays, EdU (5-ethynyl-2'-deoxyuridine) staining, TUNEL staining, flow cytometry, and transmission electron microscopy. In vivo changes in inner retinal function were evaluated by hematoxylin and eosin (H&E) staining and TUNEL staining. Western blot analyses were performed to measure the levels of related proteins. Our data showed that HP increased the levels of ATP and Ca2+ influx in Müller cells, and those increases were accompanied by the upregulation of TRPV1 and p-PLCγ1 expression. Suppression of TRPV1 or PLCG1 expression in Müller cells significantly decreased the ATP levels and intracellular Ca2+ accumulation induced by HP. Knockdown of TRPV1, PLCG1, or P2X7 significantly decreased apoptosis and autophagy in RGCs cultured in the conditioned media of HP-treated Müller cells. Moreover, TRPV1 silencing decreased RGC apoptosis and autophagy in the in vivo model of COH. Collectively, inhibition of TRPV1/PLCγ1 and P2X7 expression may be a useful therapeutic strategy for managing RGC death in glaucoma.

Whole genome sequencing analysis of alpaca suggests TRPV3 as a candidate gene for the suri phenotype

BackgroundAlpaca is a domestic South American camelid probably arising from the domestication of two wild camelids, the vicugna and the guanaco. Two phenotypes are described for alpaca, known as huacaya and suri. Huacaya fleece is characterized by compact, soft, and highly crimped fibers, while suri fleece is longer, straight, less crimped, and lustrous. The gene variants determining these phenotypes are still unknown, although previous studies suggested a dominant inheritance of the suri. Based on that, the aim of this study was the identification of the gene variants determining alpaca coat phenotypes through whole genome sequencing (WGS) analysis.ResultsThe sample used includes two test-cross alpaca families, suri × huacaya, which produced two offspring, one with the suri phenotype and one with the huacaya phenotype. The analyzed sample was expanded through the addition of WGS data from six vicugnas and six guanacos; this because we assumed the absence of the gene variants linked to the suri phenotype in these wild species. The analysis of gene variant segregation with the suri phenotype, coupled with the filtering of gene variants present in the wild species, disclosed the presence in all the suri samples of a premature termination codon (PTC) in TRPV3 (transient receptor potential cation channel subfamily V member 3), a gene known to be involved in hair growth and cycling, thermal sensation, cold tolerance and adaptation in several species. Mutations in TRPV3 were previously associated with the alteration of hair structure leading to an impaired formation of the hair canal and the hair shaft in mouse. This PTC in TRPV3, due to a G > T substitution (p.Glu475*), results in a loss of 290 amino acids from the canonical translated protein, plausibly leading to a physiological dysfunction.ConclusionThe present results suggest that the suri phenotype may arise from a TRPV3 gene variant which may explain some of the suri features such as its longer hair fibre with lower number of cuticular scales compared to huacaya.

In silico analyses of the involvement of GPR55, CB1R and TRPV1: response to THC, contribution to temporal lobe epilepsy, structural modeling and updated evolution.

The endocannabinoid (eCB) system is named after the discovery that endogenous cannabinoids bind to the same receptors as the phytochemical compounds found in Cannabis. While endogenous cannabinoids include anandamide (AEA) and 2-arachidonoylglycerol (2-AG), exogenous phytocannabinoids include Δ-9 tetrahydrocannabinol (THC) and cannabidiol (CBD). These compounds finely tune neurotransmission following synapse activation, via retrograde signaling that activates cannabinoid receptor 1 (CB1R) and/or transient receptor potential cation channel subfamily V member 1 (TRPV1). Recently, the eCB system has been linked to several neurological diseases, such as neuro-ocular abnormalities, pain insensitivity, migraine, epilepsy, addiction and neurodevelopmental disorders. In the current study, we aim to: (i) highlight a potential link between the eCB system and neurological disorders, (ii) assess if THC exposure alters the expression of eCB-related genes, and (iii) identify evolutionary-conserved residues in CB1R or TRPV1 in light of their function. To address this, we used several bioinformatic approaches, such as transcriptomic (Gene Expression Omnibus), protein-protein (STRING), phylogenic (BLASTP, MEGA) and structural (Phyre2, AutoDock, Vina, PyMol) analyzes. Using RNA sequencing datasets, we did not observe any dysregulation of eCB-related transcripts in major depressive disorders, bipolar disorder or schizophrenia in the anterior cingulate cortex, nucleus accumbens or dorsolateral striatum. Following in vivo THC exposure in adolescent mice, GPR55 was significantly upregulated in neurons from the ventral tegmental area, while other transcripts involved in the eCB system were not affected by THC exposure. Our results also suggest that THC likely induces neuroinflammation following in vitro application on mice microglia. Significant downregulation of TPRV1 occurred in the hippocampi of mice in which a model of temporal lobe epilepsy was induced, confirming previous observations. In addition, several transcriptomic dysregulations were observed in neurons of both epileptic mice and humans, which included transcripts involved in neuronal death. When scanning known interactions for transcripts involved in the eCB system (n = 12), we observed branching between the eCB system and neurophysiology, including proteins involved in the dopaminergic system. Our protein phylogenic analyzes revealed that CB1R forms a clade with CB2R, which is distinct from related paralogues such as sphingosine-1-phosphate, receptors, lysophosphatidic acid receptors and melanocortin receptors. As expected, several conserved residues were identified, which are crucial for CB1R receptor function. The anandamide-binding pocket seems to have appeared later in evolution. Similar results were observed for TRPV1, with conserved residues involved in receptor activation. The current study found that GPR55 is upregulated in neurons following THC exposure, while TRPV1 is downregulated in temporal lobe epilepsy. Caution is advised when interpreting the present results, as we have employed secondary analyzes. Common ancestors for CB1R and TRPV1 diverged from jawless vertebrates during the late Ordovician, 450 million years ago. Conserved residues are identified, which mediate crucial receptor functions.

Sterile inflammation via TRPM8 RNA-dependent TLR3-NF-kB/IRF3 activation promotes antitumor immunity in prostate cancer

Inflammation is a common condition of prostate tissue, whose impact on carcinogenesis is highly debated. Microbial colonization is a well-documented cause of a small percentage of prostatitis cases, but it remains unclear what underlies the majority of sterile inflammation reported. Here, androgen- independent fluctuations of PSA expression in prostate cells have lead us to identify a prominent function of the Transient Receptor Potential Cation Channel Subfamily M Member 8 (TRPM8) gene in sterile inflammation. Prostate cells secret TRPM8 RNA into extracellular vesicles (EVs), which primes TLR3/NF-kB-mediated inflammatory signaling after EV endocytosis by epithelial cancer cells. Furthermore, prostate cancer xenografts expressing a translation-defective form of TRPM8 RNA contain less collagen type I in the extracellular matrix, significantly more infiltrating NK cells, and larger necrotic areas as compared to control xenografts. These findings imply sustained, androgen-independent expression of TRPM8 constitutes as a promoter of anticancer innate immunity, which may constitute a clinically relevant condition affecting prostate cancer prognosis.

Larixyl acetate, a TRPC6 inhibitor, attenuates pressure overload‑induced heart failure in mice.

Heart failure is a primary cause of global mortality. In the present study, whether larixyl acetate, an inhibitor of transient receptor potential cation channel subfamily C member 6, attenuates pressure overload‑induced heart failure in mice was investigated. To test this hypothesis, a transverse aortic constriction (TAC) animal model and an angiotensin II (Ang II)‑treated H9c2 cell model were used. Cardiac and cellular structure, function and the expression levels of hypertrophy, endoplasmic reticulum (ER) stress, apoptosis, autophagy and pmTOR/mTOR related mRNAs or proteins were assessed to explore the underlying molecular mechanisms. The results indicated that treatment with TAC or Ang II leads to significant hypertrophy and dysfunction of the heart or H9c2 cells, accompanied by an increase in ER stress, apoptosis and activation of the mTOR signaling pathway, and a decrease in autophagy. The administration of larixyl acetate attenuated these impairments, which can be reversed by inhibiting autophagy through the activation of the mTOR signaling pathway. These findings suggested that larixyl acetate can effectively protect against pressure overload‑induced heart failure by enhancing autophagy and limiting ER stress and apoptosis through inhibition of the mTOR pathway.

Transient receptor potential cation channel subfamily V member 1 (TRPV1) targeted PET imaging.

Transient receptor potential cation channel subfamily V member 1 (TRPV1) was identified using capsaicin, a pungent compound that is present in red pepper. The activation of TRPV1 induces an influx of calcium ions into cells and causes excitation of sensory neurons, associating with thermal sensing, sweating and pain. TRPV1 is also identified in various types of cancer cells. The expression of TRPV1 in cancer cells depends on the type of cancer and the stage of the disease. Therefore, TRPV1 has been considered a potential target of medicinal chemistry for drug development, and blocking its activation may lead to cancer therapy and pain relief. However, the details of the pathophysiological function of TRPV1 in vivo are still unclear. To explore practical use of TRPV1, we focused on positron emission tomography imaging and developed a 11C-radiolabeled tracer to visualize TRPV1.

[Platycodin D improves pulmonary fibrosis in mice by down-regulating TRPC6 expression and reducing ROS production in lung fibroblasts].

To assess the effect of platycodin D (PD) for alleviating pulmonary fibrosis in mice and explore the underlying mechanism. C57BL/6J mouse models of pulmonary fibrosis induced by bleomycin injection into the airway were treated with daily intragastric administration of 10 mg/kg PD for 28 days. The changes of pulmonary fibrosis and the expression and distribution of transient receptor potential cation channel subfamily C member 6 (TRPC6) were evaluated with immunohistochemistry, HE staining and Sirius Red staining. Western blotting was used to detect α-SMA expression in the lung tissues of the mice. Primary cultures of mouse lung fibroblasts were pretreated with PD (2.5, 5.0, and 10 μmol/L) or larixyl acetate (LA; 10 μmol/L) before exposure to 10 ng/mL transforming growth factor-β1 (TGF-β1), and the changes in cell survival rate, expressions of collagen Ⅰ, α-SMA and TRPC6, reactive oxygen species (ROS) production, mitochondrial membrane potential, and cell proliferation capacity were assessed. Network pharmacology analysis was performed to explore the mechanism by which PD alleviated pulmonary fibrosis. PD treatment significantly alleviated pulmonary fibrosis and reduced α-SMA expression in BLM-induced mouse models (P<0.05). In TGF-β1-induced primary mouse lung fibroblasts, PD effectively inhibited the cell proliferation, reduced ROS production (P<0.0001), rescued the reduction of mitochondrial membrane potential (P<0.001), and inhibited the expressions of α-SMA and collagen Ⅰ (P<0.05). Network pharmacology analysis suggested that TRPC6 mediated the effect of PD for alleviating pulmonary fibrosis. Immunohistochemistry showed that PD significantly reduced TRPC6 expression in the lung tissues of BLM-induced mice. In primary mouse lung fibroblasts, PD significantly inhibited TGF-β1-induced TRPC6 expression (P<0.05), and LA treatment obviously lowered the expression levels of TRPC6, α-SMA and collagenⅠ (P<0.05). PD alleviated pulmonary fibrosis in mice possibly by down-regulating TRPC6 and reducing ROS production.

Propolis alleviates ulcerative colitis injury by inhibiting the protein kinase C - transient receptor potential cation channel subfamily V member 1 - calcitonin gene-related peptide/substance P (PKC-TRPV1-CGRP/SP) signaling axis.

This study investigated the protective effect of water-soluble propolis (WSP) on colonic tissues in ulcerative colitis (UC) and the role of the protein kinase C - transient receptor potential cation channel subfamily V member 1 - calcitonin gene-related peptide/substance P (PKC-TRPV1-CGRP/SP) signaling pathway. Male SD rats were divided into a control group, a UC model group, various WSP groups (Low-WSP, Medium-WSP, and High-WSP) with UC, and a salazosulfapyridine (SASP) positive control group with UC. After UC was established, the WSP and SASP groups were treated with WSP or SASP, respectively, for 7 d. Each day, body weight measurements were obtained, and the disease activity index (DAI) was recorded by observing fecal characteristics and blood in the stool. After the experiment, hematoxylin and eosin (HE) colonic tissue staining was performed to observe pathological changes, western blotting and immunohistochemistry were performed to detect PKC, TRPV1, CGRP, and SP expression in colonic tissues, and laser confocal microscopy was performed to observe the fluorescence colocalization of PKC/TRPV1, TRPV1/CGRP, and TRPV1/SP. HE staining showed significant colonic tissue structure disruption and inflammatory infiltration in the UC group. Western blotting and immunohistochemistry showed that the expression of PKC, TRPV1, CGRP, and SP in the colonic tissues of the UC group increased significantly compared with that of the control group. Compared with the UC group, the expression of PKC, TRPV1, CGRP, and SP in colonic tissues was significantly reduced in the High-WSP, Medium-WSP, and SASP groups. Immunofluorescence showed the colocalized expression of PKC/TRPV1, TRPV1/CGRP, and TRPV1/SP proteins in the colon tissue of the UC group was significantly reduced after WSP and SASP interventions compared with that of the control group. The results suggest that the mechanism of UC alleviation by propolis may inhibit the PKC-TRPV1-CGRP/SP signaling pathway and the release of inflammatory mediators, thus alleviating inflammation.

TRPM2-dependent autophagy inhibition exacerbates oxidative stress-induced CXCL16 secretion by keratinocytes in vitiligo.

Vitiligo is a depigmented skin disease due to the destruction of melanocytes. Under oxidative stress, keratinocyte-derived chemokine C-X-C motif ligand 16 (CXCL16) plays a critical role in recruiting CD8+ T cells, which kill melanocytes. Autophagy serves as a protective cell survival mechanism and impairment of autophagy has been linked to increased secretion of the proinflammatory cytokines. However, the role of autophagy in the secretion of CXCL16 under oxidative stress has not been investigated. Herein, we initially found that autophagy was suppressed in both keratinocytes of vitiligo lesions and keratinocytes exposed to oxidative stress in vitro. Autophagy inhibition also promoted CXCL16 secretion. Furthermore, upregulated transient receptor potential cation channel subfamily M member 2 (TRPM2) functioned as an upstream oxidative stress sensor to inhibit autophagy. Moreover, TRPM2-mediated Ca2+ influx activated calpain to shear autophagy related 5 (Atg5) and Atg12-Atg5 conjugate formation was blocked to inhibit autophagy under oxidative stress. More importantly, Atg5 downregulation enhanced the binding of interferon regulatory factor 3 (IRF3) to the CXCL16 promoter region by activating Tank-binding kinase 1 (TBK1), thus promoting CXCL16 secretion. These findings suggested that TRPM2-restrained autophagy promotes CXCL16 secretion via the Atg5-TBK1-IRF3 signaling pathway under oxidative stress. Inhibition of TRPM2 may serve as a potential target for the treatment of vitiligo. © 2024 The Pathological Society of Great Britain and Ireland.