Left Ventricular Hypertrophy Increases Susceptibility to Bupivacaine-induced Cardiotoxicity through Overexpression of Transient Receptor Potential Canonical Channels in Rats.

BACKGROUND: Local anesthetics, particularly potent long acting ones such as bupivacaine, can cause cardiotoxicity by inhibiting sodium ion channels; however, the impact of left ventricular hypertrophy on the cardiotoxicity and the underlying mechanisms remain undetermined. Transient receptor potential canonical (TRPC) channels are upregulated in left ventricular hypertrophy. Some transient receptor potential channel subtypes have been reported to pass relatively large cations, including protonated local anesthetics; this is known as the "pore phenomenon." The authors hypothesized that bupivacaine-induced cardiotoxicity is more severe in left ventricular hypertrophy due to upregulated TRPC channels. METHODS: The authors used a modified transverse aortic constriction model as a left ventricular hypertrophy. Cardiotoxicity caused by bupivacaine was compared between sham and aortic constriction male rats, and the underlying mechanisms were investigated by recording sodium ion channel currents and immunocytochemistry of TRPC protein in cardiomyocytes. RESULTS: The time to cardiac arrest by bupivacaine was shorter in aortic constriction rats (n =11) than in sham rats (n = 12) (mean ± SD, 1,302 ± 324 s vs. 1,034 ± 211 s; P = 0.030), regardless of its lower plasma concentration. The half-maximal inhibitory concentrations of bupivacaine toward sodium ion currents were 4.5 and 4.3 µM, which decreased to 3.9 and 2.6 µM in sham and aortic constriction rats, respectively, upon coapplication of 1-oleoyl-2-acetyl-sn-glycerol, a TRPC3 channel activator. In both groups, sodium ion currents were unaffected by QX-314, a positively charged lidocaine derivative, that hardly permeates the cell membrane, but was significantly decreased with QX-314 and 1-oleoyl-2-acetyl-sn-glycerol coapplication (sham: 79 ± 10% of control; P = 0.004; aortic constriction: 47± 27% of control; P = 0.020; n = 5 cells per group). Effects of 1-oleoyl-2-acetyl-sn-glycerol were antagonized by a specific TRPC3 channel inhibitor. CONCLUSIONS: Left ventricular hypertrophy exacerbated bupivacaine-induced cardiotoxicity, which could be a consequence of the "pore phenomenon" of TRPC3 channels upregulated in left ventricular hypertrophy.

Overexpression of certain transient receptor potential and Orai channels in prostate cancer is associated with decreased risk of systemic recurrence after radical prostatectomy.

BACKGROUND: Several studies had suggested the potential role of calcium signaling in prostate cancer (PCa) prognosis and agressiveness. We aimed to investigate selected proteins contributing to calcium (Ca2+ ) signaling, (Orai, stromal interaction molecule (STIM), and transient receptor potential (TRP) channels) and involved in cancer hallmarks, as independent predictors of systemic recurrence after radical prostatectomy (RP). METHODS: A case-control study including 112 patients with clinically localized PCa treated by RP between 2002 and 2009 and with at least 6-years' follow-up. Patients were divided into two groups according to the absence or presence of systemic recurrence. Expression levels of 10 proteins involved in Ca2+ signaling (TRPC1, TRPC4, TRPV5, TRPV6, TRPM8, STIM1, STIM2, Orai1, Orai2, and Orai3), were assessed by immunohistochemistry using tissue microarrays (TMAs) constructed from paraffin-embedded PCa specimens. The level of expression of the various transcripts in PCa was assessed using quantitative polymerase chain reaction (qPCR) analysis. RNA samples for qPCR were obtained from fresh frozen tissue samples of PCa after laser capture microdissection on RP specimens. Relative gene expression was analyzed using the 2-▵▵Ct method. RESULTS: Multivariate analysis showed that increased expression of TRPC1, TRPC4, TRPV5, TRPV6, TRPM8, and Orai2 was significantly associated with a lower risk of systemic recurrence after RP, independently of the prostate-specific antigen (PSA) level, percentage of positive biopsies, and surgical margin (SM) status (P = .007, P = .01, P < .001, P = .0065, P = .007, and P = .01, respectively). For TRPC4, TRPV5, and TRPV6, this association was also independent of Gleason score and pT stage. Moreover, overexpression of TRPV6 and Orai2 was significantly associated with longer time to recurrence after RP (P = .048 and .023, respectively). Overexpression of TRPC4, TRPV5, TRPV6, and Orai2 transcripts was observed in group R- (3.71-, 5.7-, 1.14-, and 2.65-fold increase, respectively). CONCLUSIONS: This is the first study to suggest the independent prognostic value of certain proteins involved in Ca2+ influx in systemic recurrence after RP: overexpression of TRPC1, TRPC4, TRPV5, TRPV6, TRPM8, and Orai2 is associated with a lower risk of systemic recurrence. TRPC4, TRPV5, and TRPV6 appear to be particularly interesting, as they are independent of the five commonly used predictive factors, that is, PSA, percentage of positive biopsies, SM status, Gleason score, and pT stage.

Exosomal release through TRPML1-mediated lysosomal exocytosis is required for adipogenesis.

The lysosomal Ca2+ permeable channel TRPML1 (MCOLN1) plays key roles in lysosomal membrane trafficking, including the fusion of late endosomes to lysosomes and lysosomal exocytosis, both of which are essential for release of exosomes into the extracellular milieu. Multiple lines of evidence indicate that the contents of adipocyte-derived exosomes mediate diverse cellular responses, including adipogenic differentiation. In this study, we aimed to define the potential roles of TRPML1 in lysosomal membrane trafficking during adipogenesis and in exosomal release. In response to adipogenic stimuli, the endogenous TRPML1 expression in OP9 pre-adipocytes was increased in a time-dependent manner, and the acute deletion of TRPML1 reduced lipid synthesis and expression of differentiation-related marker genes. Notably, mature adipocyte-derived exosomes were found to be necessary for adipogenesis and were dependent on TRPML1-mediated lysosomal exocytosis. Taken together, our findings indicate that TRPML1 mediates diverse roles in adipocyte differentiation and exosomal release. Further, we propose that TRPML1 should be considered as a regulator of obesity-related diseases.

Purification of Functional Human TRP Channels Recombinantly Produced in Yeast.

(1) Background: Human transient receptor potential (TRP) channels constitute a large family of ion-conducting membrane proteins that allow the sensation of environmental cues. As the dysfunction of TRP channels contributes to the pathogenesis of many widespread diseases, including cardiac disorders, these proteins also represent important pharmacological targets. TRP channels are typically produced using expensive and laborious mammalian or insect cell-based systems. (2) Methods: We demonstrate an alternative platform exploiting the yeast Saccharomyces cerevisiae capable of delivering high yields of functional human TRP channels. We produce 11 full-length human TRP members originating from four different subfamilies, purify a selected subset of these to a high homogeneity and confirm retained functionality using TRPM8 as a model target. (3) Results: Our findings demonstrate the potential of the described production system for future functional, structural and pharmacological studies of human TRP channels.

Ethanol's Effects on Transient Receptor Potential Channel Expression in Brain Microvascular Endothelial Cells.

Ethanol (EtOH), the main ingredient in alcoholic beverages, is well known for its behavioral, physiological, and immunosuppressive effects. There is evidence that EtOH acts through protein targets to exert its physiological effects; however, the mechanisms underlying EtOH's effects on inflammatory processes, particularly at the blood-brain barrier (BBB), are still poorly understood. Transient receptor potential (TRP) channels, the vanguards of human sensory systems, are novel molecular receptors significantly affected by EtOH, and are heavily expressed in brain microvascular endothelial cells (BMVECs), one of the cellular constituents of the BBB. EtOH's actions on endothelial TRP channels could affect intracellular Ca2+ and Mg2+ dynamics, which mediate leukocyte adhesion to endothelial cells and endothelial permeability at the BBB, thus altering immune and inflammatory responses. We examined the basal expression profiles of all 29 known mammalian TRP channels in mouse BMVECs and determined both EtOH concentration- and time-dependent effects on TRP expression using a PCR array. We also generated an in vitro BBB model to examine the involvement of a chosen TRP channel, TRP melastatin 7 (TRPM7), in EtOH-mediated alteration of BBB permeability. With the exception of the akyrin subfamily, members of five TRP subfamilies were expressed in mouse BMVECs, and their expression levels were modulated by EtOH in a concentration-dependent manner. In the in vitro BBB model, TRPM7 antagonists further enhanced EtOH-mediated alteration of BBB permeability. Because of the diversity of TRP channels in BMVECs that regulate cellular processes, EtOH can affect Ca2+/Mg2+ signaling, immune responses, lysosomal functions as well as BBB integrity.

Effects of nerve growth factor neutralization on TRP channel expression in laser-captured bladder afferent neurons in mice with spinal cord injury.

Nerve growth factor (NGF) is reportedly involved in the changes in C-fiber bladder afferent pathways that induce detrusor overactivity (DO) following spinal cord injury (SCI). This study examined the roles of NGF in TRP channel expression in bladder afferent neurons in mice with SCI using laser-capture microdissection (LCM) methods. Spinal intact (SI) and SCI mice were divided into 3 groups: (1) SI with vehicle treatment; (2) SCI with vehicle treatment; and (3) SCI with anti-NGF antibody. Two weeks after SCI, an osmotic pump was placed subcutaneously into the back of the mice and vehicle or anti-NGF antibody was administered at a rate of 10 µg/kg per hour for two weeks. Four weeks after SCI, the L6 dorsal root ganglia (DRG) were removed. Expression of the TRPV1, TRPC1, TRPC3, and TRPC6 genes was analyzed using real-time polymerase chain reaction (PCR) following LCM of the bladder afferent neurons, which were labeled by Fast Blue injected into the bladder wall 1 week prior to tissue removal. The mRNA expression of TRPV1 was found to be higher in vehicle-treated SCI mice than in SI mice. The expression level of TRPC3 and TRPC6 in vehicle-treated SCI mice was lower than in SI mice. However, in SCI mice treated with anti-NGF antibody, the mRNA expression of TRPV1 was lower, and the mRNA levels of TRPC3 and TRPC6 were higher than in vehicle-SCI mice. These results suggest that the NGF-dependent changes in specific TRP channel genes, such as TRPV1, TRPC3, and TRPC6, could be involved in SCI-induced afferent hyperexcitability and DO.

Gene expression changes of thermo-sensitive transient receptor potential channels in obese mice.

Adipose tissues play key roles in energy homeostasis. Brown adipocytes and beige adipocytes in white adipose tissue (WAT) share the similar characters of thermogenesis, both of them could be potential targets for obesity management. Several thermo-sensitive transient receptor potential channels (thermoTRPs) are shown to be involved in adipocyte biology. However, the expression pattern of thermoTRPs in adipose tissues from obese mice is still unknown. The mRNA expression of thermoTRPs in subcutaneous WAT (sWAT) and interscapular brown adipose tissue (iBAT) from lean and obese mice were measured using reverse transcriptase-quantitative PCRs (RT-qPCR). The results demonstrated that all 10 thermoTRPs are expressed in both iBAT and sWAT, and without significant difference in the mRNA expression level of thermoTRPs between these two tissues. Moreover, Trpv1 and Trpv3 mRNA expression levels in both iBAT and sWAT were significantly decreased in high fat diet (HFD)-induced obese mice and db/db (leptin receptor deficient) mice. Trpm2 mRNA expression level was significantly decreased only in sWAT from HFD-induced obese mice and db/db mice. On the other hand, Trpv2 and Trpv4 mRNA expression levels in iBAT and sWAT were significantly increased in HFD-induced obese mice and db/db mice. Taken together, we conclude that all 10 thermoTRPs are expressed in iBAT and sWAT. And several thermoTRPs differentially expressed in adipose tissues from HFD-induced obese mice and db/db mice, suggesting a potential involvement in anti-obesity regulations.

Exacerbating effects of PM2.5 in OVA-sensitized and challenged mice and the expression of TRPA1 and TRPV1 proteins in lungs.

OBJECTIVE: To investigate the effects of particulate matter ≤ 2.5 microns (PM2.5) on asthma-related phenotypes and on lung expression of TRPA1 and TRPV1 proteins in a mouse model of asthma. METHODS: Female BALB/c mice were utilized to establish 28- and 42-day asthma models. Mice were sensitized with ovalbumin (OVA) and challenged with OVA, OVA plus normal saline (NS), or OVA plus PM2.5 at two doses, 1.6 or 8.0 mg kg-1. PM2.5 was instilled intratracheally without anesthesia. After the final OVA challenge was performed, 24 hours later, the changes in airway resistance (RI) and lung dynamic compliance (Cdyn) in response to acetylcholine chloride (ACH) were evaluated, and blood, bronchoalveolar lavage fluid (BALF) and lung tissue were taken at that time. The number of eosinophils in blood and various leukocytes in BALF were determined. Lung protein was extracted and probed for TRPA1 and TRPV1 expression. Interleukin (IL)-13, substance P (SP), prostaglandin D2 (PGD2) and nerve growth factor (NGF) in BALF were measured by enzyme-linked immunosorbent assay. RESULTS: PM2.5 treated mice showed significantly greater changes in the number of inflammatory cells in blood and BALF, in RI and Cdyn in response to ACH, and in lung histopathology, indicated by inflammatory cell infiltration, thickened bronchial smooth muscles and bronchial mucosa damage, compared to controls. In addition, higher expression of TRPA1 and TRPV1 in lung and IL-13, SP, PGD2 and NGF in BALF were seen in mice exposed to PM2.5. All effects were most pronounced in mice in the 42-day model. CONCLUSIONS: PM2.5 exacerbates effects of asthma in this model, possibly by regulating TRPA1 and TRPV1 and the relevant neurokines.

Localization and expression patterns of TRP channels in submandibular gland development.

OBJECTIVE: Expression of Transient receptor potential (TRP) channels: TRP canonical (TRPC)1, TRP vanilloid (TRPV)3, TRPV4 and TRP melastatin (TRPM)8 in adult rat salivary gland has recently been reported. The authors investigated expression of these TRP channels in the submandibular gland during early developmental stage in which the cell constitution is different, and discussed the function of TRP in the submandibular gland in early development. DESIGN: Using rat submandibular gland at embryonic days (E)18 and E20 and postnatal days (PN)0 and PN5 and PN28, expression of TRPV3, TRPV4, TRPC1 and TRPM8 was investigated using real-time polymerase chain reaction (RT-PCR) and immunohistochemistry. RESULTS: All TRP channels were expressed in cells constituting the submandibular gland in early developmental stage, but an increase in the expression level at PN5 on RT-PCR was significant compared with those at E18, PN0 and PN28 in TRPC1 and TRPV4 channels, whereas an increase was observed but not significant in the others. On immunohistochemical staining at PN5, whereas strong reactions of anti-TRPM8 antibody, anti-TRPV3 and anti-TRPV4 antibodies were observed in cells which proliferated from a terminal portion of cells arranged tubular structure which previously constituted mostly the submandibular gland. CONCLUSION: It was clarified that TRP channels are expressed in the rat submandibular gland in early developmental stage although cells constituting the submandibular gland are different from those in adult animals, suggesting that these TRP channels are involved in cell differentiation in at PN5 into the adult submandibular gland during early development.

Characterization of Transient Receptor Potential Vanilloid-1 (TRPV1) Variant Activation by Coal Fly Ash Particles and Associations with Altered Transient Receptor Potential Ankyrin-1 (TRPA1) Expression and Asthma.

Transient receptor potential (TRP) channels are activated by environmental particulate materials. We hypothesized that polymorphic variants of transient receptor potential vanilloid-1 (TRPV1) would be uniquely responsive to insoluble coal fly ash compared with the prototypical soluble agonist capsaicin. Furthermore, these changes would manifest as differences in lung cell responses to these agonists and perhaps correlate with changes in asthma symptom control. The TRPV1-I315M and -T469I variants were more responsive to capsaicin and coal fly ash. The I585V variant was less responsive to coal fly ash particles due to reduced translation of protein and an apparent role for Ile-585 in activation by particles. In HEK-293 cells, I585V had an inhibitory effect on wild-type TRPV1 expression, activation, and internalization/agonist-induced desensitization. In normal human bronchial epithelial cells, IL-8 secretion in response to coal fly ash treatment was reduced for cells heterozygous for TRPV1-I585V. Finally, both the I315M and I585V variants were associated with worse asthma symptom control with the effects of I315M manifesting in mild asthma and those of the I585V variant manifesting in severe, steroid-insensitive individuals. This effect may be due in part to increased transient receptor potential ankyrin-1 (TRPA1) expression by lung epithelial cells expressing the TRPV1-I585V variant. These findings suggest that specific molecular interactions control TRPV1 activation by particles, differential activation, and desensitization of TRPV1 by particles and/or other agonists, and cellular changes in the expression of TRPA1 as a result of I585V expression could contribute to variations in asthma symptom control.

Endoglin selectively modulates transient receptor potential channel expression in left and right heart failure.

INTRODUCTION: Transient receptor potential (TRP) channels are broadly expressed cation channels that mediate diverse physiological stimuli and include canonical (TRPC), melastatin (TRPM), and vanilloid (TRPV) subtypes. Recent studies have implicated a role for TRPC6 channels as an important component of signaling via the cytokine, transforming growth factor beta 1 (TGFß1) in right (RV) or left ventricular (LV) failure. Endoglin (Eng) is a transmembrane glycoprotein that promotes TRPC6 expression and TGFß1 activity. No studies have defined biventricular expression of all TRP channel family members in heart failure. HYPOTHESIS: We hypothesized that heart failure is associated with distinct patterns of TRP channel expression in the LV and RV. METHODS: Paired viable LV and RV free wall tissue was obtained from human subjects with end-stage heart failure (n=12) referred for cardiac transplantation or biventricular assist device implantation. Paired LV and RV samples from human subjects without heart failure served as controls (n=3). To explore a functional role for Eng as a regulator of TRP expression in response to RV or LV pressure overload, wild-type (Eng+/+) and Eng haploinsufficient (Eng+/-) mice were exposed to thoracic aortic (TAC) or pulmonary arterial (PAC) constriction for 8weeks. Biventricular tissue was analyzed by real-time polymerase chain reaction. RESULTS: Compared to nonfailing human LV and RV samples, mRNA levels of TRPC1, 3, 4, 6, and TRPV-2 were increased and TRPM2, 3, and 8 were decreased in failing LV and RV samples. TRPC1 and 6 levels were higher in failing RV compared to failing LV samples. After TAC, murine LV levels of TPRC1 and 6 were increased in both Eng+/+ and Eng+/- mice compared to sham controls. LV levels of TRPC4, TRPM3 and 7, TRPV2 and 4 were increased in Eng+/+, not in Eng+/- mice after TAC. After PAC, all TRP channel family members were increased in the RV, but not LV, of Eng+/+ compared to sham controls. In contrast to Eng+/+, PAC did not increase RV or LV levels of TRP channels in Eng+/- mice. CONCLUSIONS: This is the first study to demonstrate that TRP channels exhibit distinct profiles of expression in the LV and RV of patients with heart failure and in murine models of univentricular pressure overload. We further introduce that the TGFß1 coreceptor Eng selectively regulates expression of multiple TRP channels in the setting of LV or RV pressure overload.

Transient receptor potential ankyrin 1 (TRPA1) is functionally expressed in primary human osteoarthritic chondrocytes.

BACKGROUND: Transient receptor potential ankyrin 1 (TRPA1) is a membrane-associated cation channel, widely expressed in neuronal cells and involved in nociception and neurogenic inflammation. We showed recently that TRPA1 mediates cartilage degradation and joint pain in the MIA-model of osteoarthritis (OA) suggesting a hitherto unknown role for TRPA1 in OA. Therefore, we aimed to investigate whether TRPA1 is expressed and functional in human OA chondrocytes. METHODS: Expression of TRPA1 in primary human OA chondrocytes was assessed by qRT-PCR and Western blot. The functionality of the TRPA1 channel was assessed by Ca(2+)-influx measurements. Production of MMP-1, MMP-3, MMP-13, IL-6, and PGE2 subsequent to TRPA1 activation was measured by immunoassay. RESULTS: We show here for the first time that TRPA1 is expressed in primary human OA chondrocytes and its expression is increased following stimulation with inflammatory factors IL-1ß, IL-17, LPS, and resistin. Further, the TRPA1 channel was found to be functional, as stimulation with the TRPA1 agonist AITC caused an increase in Ca(2+) influx, which was attenuated by the TRPA1 antagonist HC-030031. Genetic depletion and pharmacological inhibition of TRPA1 downregulated the production of MMP-1, MMP-3, MMP-13, IL-6, and PGE2 in osteoarthritic chondrocytes and murine cartilage, respectively. CONCLUSIONS: The TRPA1 cation channel was found to be functionally expressed in primary human OA chondrocytes, which is an original finding. The presence and inflammatory and catabolic effects of TRPA1 in human OA chondrocytes propose a highly intriguing role for TRPA1 as a pathogenic factor and drug target in OA.

Mechanosensory and ATP Release Deficits following Keratin14-Cre-Mediated TRPA1 Deletion Despite Absence of TRPA1 in Murine Keratinocytes.

Keratinocytes are the first cells that come into direct contact with external tactile stimuli; however, their role in touch transduction in vivo is not clear. The ion channel Transient Receptor Potential Ankyrin 1 (TRPA1) is essential for some mechanically-gated currents in sensory neurons, amplifies mechanical responses after inflammation, and has been reported to be expressed in human and mouse skin. Other reports have not detected Trpa1 mRNA transcripts in human or mouse epidermis. Therefore, we set out to determine whether selective deletion of Trpa1 from keratinocytes would impact mechanosensation. We generated K14Cre-Trpa1fl/fl mice lacking TRPA1 in K14-expressing cells, including keratinocytes. Surprisingly, Trpa1 transcripts were very poorly detected in epidermis of these mice or in controls, and detection was minimal enough to preclude observation of Trpa1 mRNA knockdown in the K14Cre-Trpa1fl/fl mice. Unexpectedly, these K14Cre-Trpa1fl/fl mice nonetheless exhibited a pronounced deficit in mechanosensitivity at the behavioral and primary afferent levels, and decreased mechanically-evoked ATP release from skin. Overall, while these data suggest that the intended targeted deletion of Trpa1 from keratin 14-expressing cells of the epidermis induces functional deficits in mechanotransduction and ATP release, these deficits are in fact likely due to factors other than reduction of Trpa1 expression in adult mouse keratinocytes because they express very little, if any, Trpa1.

Biodentine Reduces Tumor Necrosis Factor Alpha-induced TRPA1 Expression in Odontoblastlike Cells.

INTRODUCTION: The transient receptor potential (TRP) ion channels have emerged as important cellular sensors in both neuronal and non-neuronal cells, with TRPA1 playing a central role in nociception and neurogenic inflammation. The functionality of TRP channels has been shown to be modulated by inflammatory cytokines. The aim of this study was to investigate the effect of inflammation on odontoblast TRPA1 expression and to determine the effect of Biodentine (Septodent, Paris, France) on inflammatory-induced TRPA1 expression. METHODS: Immunohistochemistry was used to study TRPA1 expression in pulp tissue from healthy and carious human teeth. Pulp cells were differentiated to odontoblastlike cells in the presence of 2 mmol/L beta-glycerophosphate, and these cells were used in quantitative polymerase chain reaction, Western blotting, calcium imaging, and patch clamp studies. RESULTS: Immunofluorescent staining revealed TRPA1 expression in odontoblast cell bodies and odontoblast processes, which was more intense in carious versus healthy teeth. TRPA1 gene expression was induced in cultured odontoblastlike cells by tumor necrosis factor alpha, and this expression was significantly reduced in the presence of Biodentine. The functionality of the TRPA1 channel was shown by calcium microfluorimetry and patch clamp recording, and our results showed a significant reduction in tumor necrosis factor alpha-induced TRPA1 responses after Biodentine treatment. CONCLUSIONS: In conclusion, this study showed TRPA1 to be modulated by caries-induced inflammation and that Biodentine reduced TRPA1 expression and functional responses.

Environmental cold exposure increases blood flow and affects pain sensitivity in the knee joints of CFA-induced arthritic mice in a TRPA1-dependent manner.

BACKGROUND: The effect of cold temperature on arthritis symptoms is unclear. The aim of this study was to investigate how environmental cold affects pain and blood flow in mono-arthritic mice, and examine a role for transient receptor potential ankyrin 1 (TRPA1), a ligand-gated cation channel that can act as a cold sensor. METHODS: Mono-arthritis was induced by unilateral intra-articular injection of complete Freund's adjuvant (CFA) in CD1 mice, and in mice either lacking TRPA1 (TRPA1 KO) or respective wildtypes (WT). Two weeks later, nociception and joint blood flow were measured following exposure to 10 °C (1 h) or room temperature (RT). Primary mechanical hyperalgesia in the knee was measured by pressure application apparatus; secondary mechanical hyperalgesia by automated von Frey system; thermal hyperalgesia by Hargreaves technique, and weight bearing by the incapacitance test. Joint blood flow was recorded by full-field laser perfusion imager (FLPI) and using clearance of (99m)Technetium. Blood flow was assessed after pretreatment with antagonists of either TRPA1 (HC-030031), substance P neurokinin 1 (NK1) receptors (SR140333) or calcitonin gene-related peptide (CGRP) (CGRP8-37). TRPA1, TAC-1 and CGRP mRNA levels were examined in dorsal root ganglia, synovial membrane and patellar cartilage samples. RESULTS: Cold exposure caused bilateral primary mechanical hyperalgesia 2 weeks after CFA injection, in a TRPA1-dependent manner. In animals maintained at RT, clearance techniques and FLPI showed that CFA-treated joints exhibited lower blood flow than saline-treated joints. In cold-exposed animals, this reduction in blood flow disappears, and increased blood flow in the CFA-treated joint is observed using FLPI. Cold-induced increased blood flow in CFA-treated joints was blocked by HC-030031 and not observed in TRPA1 KOs. Cold exposure increased TRPA1 mRNA levels in patellar cartilage, whilst reducing it in synovial membranes from CFA-treated joints. CONCLUSIONS: We provide evidence that environmental cold exposure enhances pain and increases blood flow in a mono-arthritis model. These changes are dependent on TRPA1. Thus, TRPA1 may act locally within the joint to influence blood flow via sensory nerves, in addition to its established nociceptive actions.

Effects of Pseudomonas aeruginosa infection on the expression profile of transient receptor potential-like (TRPL) gene from Drosophila melanogaster.

In an endeavor to monitor the effects of experimental infections with Pseudomonas aeruginosa on gene expression profiles of the eukaryotic model host, we focused on transient receptor potential-like (trpl) pleiotropic gene of Drosophila melanogaster (the fruit fly). Herein we report qRT-PCR data derived from experimental infections of male fruit flies with different genetic backgrounds by pricking and ingesta procedures, as compared to previous results obtained by microarray technology consecutive to ingesta experiments. Whenever statistically significant, the qRT-PCR results obtained for the whole body and intestine of Oregon wild-type flies infected with P. aeruginosa are in agreement with the microarray ones. Both expression profiling technologies revealed similar values of downregulation, supporting the robustness of trpl as a novel gene model for inquiring hostpathogen interactions. On the other hand, the downregulation of trpl in gammaCop mutant males is not confirmed by qRT-PCR data, suggesting that this mutant background is more sensitive to environmental and experimental conditions.

Monosodium iodoacetate-induced inflammation and joint pain are reduced in TRPA1 deficient mice--potential role of TRPA1 in osteoarthritis.

OBJECTIVES: Intra-articularly injected monosodium iodoacetate (MIA) induces joint pathology mimicking osteoarthritis (OA) and it is a widely used experimental model of OA. MIA induces acute inflammation, cartilage degradation and joint pain. Transient Receptor Potential Ankyrin 1 (TRPA1) is an ion channel known to mediate nociception and neurogenic inflammation. Here, we tested the hypothesis that TRPA1 would be involved in the development of MIA-induced acute inflammation, cartilage changes and joint pain. METHODS: The effects of pharmacological blockade (by TCS 5861528) and genetic depletion of TRPA1 were studied in MIA-induced acute paw inflammation. Cartilage changes (histological scoring) and joint pain (weight-bearing test) in MIA-induced experimental OA were compared between wild type and TRPA1 deficient mice. The effects of MIA were also studied in primary human OA chondrocytes and in mouse cartilage. RESULTS: MIA evoked acute inflammation, degenerative cartilage changes and joint pain in wild type mice. Interestingly, these responses were attenuated in TRPA1 deficient animals. MIA-induced paw inflammation was associated with increased tissue levels of substance P; and the inflammatory edema was reduced by pretreatment with catalase, with the TRPA1 antagonist TCS 5861528 and with the neurokinin 1 receptor antagonist L703,606. In chondrocytes, MIA enhanced interleukin-1 induced cyclooxygenase-2 (COX-2) expression, an effect that was blunted by pharmacological inhibition and genetic depletion of TRPA1. CONCLUSIONS: TRPA1 was found to mediate acute inflammation and the development of degenerative cartilage changes and joint pain in MIA-induced experimental OA in the mouse. The results reveal TRPA1 as a potential mediator and drug target in OA.

Gene expressions of TRP channels in glioblastoma multiforme and relation with survival.

Glioblastoma multiforme (GBM) is one of the most lethal forms of cancer in humans, with a median survival of 10 to 12 months. Glioblastoma is highly malignant since the cells are supported by a great number of blood vessels. Although new treatments have been developed by increasing knowledge of molecular nature of the disease, surgical operation remains the standard of care. The TRP (transient receptor potential) superfamily consists of cation-selective channels that have roles in sensory physiology such as thermo- and osmosensation and in several complex diseases such as cancer, cardiovascular, and neuronal diseases. The aim of this study was to investigate the expression levels of TRP channel genes in patients with glioblastoma multiforme and to evaluate the relationship between TRP gene expressions and survival of the patients. Thirty-three patients diagnosed with glioblastoma were enrolled to the study. The expression levels of 21 TRP genes were quantified by using qRT-PCR with dynamic array 48 × 48 chip (BioMark HD System, Fluidigm, South San Francisco, CA, USA). TRPC1, TRPC6, TRPM2, TRPM3, TRPM7, TRPM8, TRPV1, and TRPV2 were found significantly higher in glioblastoma patients. Moreover, there was a significant relationship between the overexpression of TRP genes and the survival of the patients. These results demonstrate for the first time that TRP channels contribute to the progression and survival of the glioblastoma patients.

Regulation of TRPML1 function.

TRPML1 is a ubiquitously expressed cation channel found on lysosomes and late endosomes. Mutations in TRPML1 cause mucolipidosis type IV and it has been implicated in Alzheimer's disease and HIV. However, the mechanisms by which TRPML1 activity is regulated are not well understood. This review summarizes the current understanding of TRPML1 activation and regulation.

TRP Channels Localize to Subdomains of the Apical Plasma Membrane in Human Fetal Retinal Pigment Epithelium.

PURPOSE: Calcium regulates many functions of the RPE. Its concentration in the subretinal space and RPE cytoplasm is closely regulated. Transient receptor potential (TRP) channels are a superfamily of ion channels that are moderately calcium-selective. This study investigates the subcellular localization and potential functions of TRP channels in a first-passage culture model of human fetal RPE (hfRPE). METHODS: The RPE isolated from 15- to 16-week gestation fetuses were maintained in serum-free media. Cultures were treated with barium chloride (BaCl2) in the absence and presence of TRP channel inhibitors and monitored by the transepithelial electrical resistance (TER). The expression of TRP channels was determined using quantitative RT-PCR, immunoblotting, and immunofluorescence confocal microscopy. RESULTS: Barium chloride substantially decreased TER and disrupted cell-cell contacts when added to the apical surface of RPE, but not when added to the basolateral surface. The effect could be partially blocked by the general TRP inhibitor, lanthanum chloride (LaCl3, ~75%), or an inhibitor of calpain (~25%). Family member-specific inhibitors, ML204 (TRPC4) and HC-067047 (TRPV4), had no effect on basal channel activity. Expression of TRPC4, TRPM1, TRPM3, TRPM7, and TRPV4 was detected by RT-PCR and immunoblotting. The TRPM3 localized to the base of the primary cilium, and TRPC4 and TRPM3 localized to apical tight junctions. The TRPV4 localized to apical microvilli in a small subset of cells. CONCLUSIONS: The TRP channels localized to subdomains of the apical membrane, and BaCl2 was only able to dissociate tight junctions when presented to the apical membrane. The data suggest a potential role for TRP channels as sensors of [Ca(2+)] in the subretinal space.