scholarly journals Functional expression of purinergic P2 receptors and transient receptor potential channels by the human urothelium

2013 ◽  
Vol 305 (3) ◽  
pp. F396-F406 ◽  
Author(s):  
Saqib Shabir ◽  
William Cross ◽  
Lisa A. Kirkwood ◽  
Joanna F. Pearson ◽  
Peter A. Appleby ◽  
...  
Keyword(s):  
Transient Receptor Potential ◽  
Trp Channels ◽  
Receptor Potential ◽  
Functional Expression ◽  
P2 Receptors ◽  
Transient Receptor Potential Channels ◽  
Tissue Homeostasis ◽  
Ligand Selectivity ◽  
Intracellular Ca ◽  
Transient Receptor

In addition to its role as a physical barrier, the urothelium is considered to play an active role in mechanosensation. A key mechanism is the release of transient mediators that activate purinergic P2 receptors and transient receptor potential (TRP) channels to effect changes in intracellular Ca2+. Despite the implied importance of these receptors and channels in urothelial tissue homeostasis and dysfunctional bladder disease, little is known about their functional expression by the human urothelium. To evaluate the expression and function of P2X and P2Y receptors and TRP channels, the human ureter and bladder were used to separate urothelial and stromal tissues for RNA isolation and cell culture. RT-PCR using stringently designed primer sets was used to establish which P2 and TRP species were expressed at the transcript level, and selective agonists/antagonists were used to confirm functional expression by monitoring changes in intracellular Ca2+ and in a scratch repair assay. The results confirmed the functional expression of P2Y4 receptors and excluded nonexpressed receptors/channels (P2X1, P2X3, P2X6, P2Y6, P2Y11, TRPV5, and TRPM8), while a dearth of specific agonists confounded the functional validation of expressed P2X2, P2X4, P2Y1, P2Y2, TRPV2, TRPV3, TRPV6 and TRPM7 receptors/channels. Although a conventional response was elicited in control stromal-derived cells, the urothelial cell response to well-characterized TRPV1 and TRPV4 agonists/antagonists revealed unexpected anomalies. In addition, agonists that invoked an increase in intracellular Ca2+ promoted urothelial scratch repair, presumably through the release of ATP. The study raises important questions about the ligand selectivity of receptor/channel targets expressed by the urothelium. These pathways are important in urothelial tissue homeostasis, and this opens the possibility of selective drug targeting.

Does serotonin deficiency lead to anosmia, ageusia and dysfunctional chemesthesis in COVID-19?

2021 ◽  
Author(s):  
Amarnath Sen
Keyword(s):  
Selective Serotonin Reuptake Inhibitors ◽  
Transient Receptor Potential ◽  
Trp Channels ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
Taste Receptor ◽  
Receptor Potential ◽  
Transient Receptor Potential Channels ◽  
Host Cells ◽  
Potential Channels ◽  
Transient Receptor

Anosmia, ageusia and impaired chemesthetic sensations are quite common in coronavirus patients. Different mechanisms have been proposed to explain the anosmia and ageusia of COVID-19 patients, though for reversible anosmia and ageusia, which are resolved quickly, the proposed mechanisms seem to be incomplete. In addition, the reason behind the impaired chemesthetic sensations of some coronavirus patients remains unknown. It is proposed that in coronavirus patients, there is depletion of tryptophan (an essential amino acid), as ACE2, a key element in the process of absorption of tryptophan from food, is significantly reduced due to the attack of coronavirus which use ACE2 as the receptor for its entry into the host cells. Incidentally, the depletion of tryptophan should lead to deficiency of serotonin (5-HT) in SARS-COV-2 patients because tryptophan is the precursor in the synthesis of 5-HT. Such 5-HT deficiency not only explains fast resolved anosmia and ageusia, but also dysfunctional chemesthesis, given the fact that 5-HT is an important neuromodulator in the olfactory neurons and taste receptor cells and 5-HT also enhances the nociceptor activity of transient receptor potential channels (TRP channels) responsible for chemesthetic sensations. The female predominance of olfactory and gustatory dysfunctions can also be explained by considering low 5-HT levels in women. In addition, 5-HT deficiency worsens silent hypoxemia and explains why hypoxic pulmonary vasoconstriction is nearly absent in coronavirus patients leading to poor outcome. Hence, clinical trials should be conducted on coronavirus patients to find out how different selective serotonin reuptake inhibitors (SSRIs) and serotonin agonists work out in eliminating or improving the olfactory, gustatory and chemesthetic dysfunctions as well as hypoxemia.

scholarly journals Transient Receptor Potential Channels as an Emerging Target for the Treatment of Parkinson’s Disease: An Insight Into Role of Pharmacological Interventions

2020 ◽  
Vol 8 ◽  
Author(s):  
Bhupesh Vaidya ◽  
Shyam Sunder Sharma
Keyword(s):  
Oxidative Stress ◽  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Molecular Mechanisms ◽  
Transient Receptor Potential ◽  
Trp Channels ◽  
Neurodegenerative Disorder ◽  
Receptor Potential ◽  
Transient Receptor Potential Channels ◽  
Transient Receptor

Parkinson’s disease (PD) is a neurodegenerative disorder characterized by the symptoms of motor deficits and cognitive decline. There are a number of therapeutics available for the treatment of PD, but most of them suffer from serious side effects such as bradykinesia, dyskinesia and on-off effect. Therefore, despite the availability of these pharmacological agents, PD patients continue to have an inferior quality of life. This has warranted a need to look for alternate strategies and molecular targets. Recent evidence suggests the Transient Receptor Potential (TRP) channels could be a potential target for the management of motor and non-motor symptoms of PD. Though still in the preclinical stages, agents targeting these channels have shown immense potential in the attenuation of behavioral deficits and signaling pathways. In addition, these channels are known to be involved in the regulation of ionic homeostasis, which is disrupted in PD. Moreover, activation or inhibition of many of the TRP channels by calcium and oxidative stress has also raised the possibility of their paramount involvement in affecting the other molecular mechanisms associated with PD pathology. However, due to the paucity of information available and lack of specificity, none of these agents have gone into clinical trials for PD treatment. Considering their interaction with oxidative stress, apoptosis and excitotoxicity, TRP channels could be considered as a potential future target for the treatment of PD.

scholarly journals Molecular Regulations and Functions of the Transient Receptor Potential Channels of the Islets of Langerhans and Insulinoma Cells

Cells ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 685 ◽  
Author(s):  
Md. Shahidul Islam
Keyword(s):  
Insulin Secretion ◽  
Electrical Activity ◽  
Islets Of Langerhans ◽  
Transient Receptor Potential ◽  
Trp Channels ◽  
Receptor Potential ◽  
Transient Receptor Potential Channels ◽  
Β Cells ◽  
Transient Receptor ◽  
Insulinoma Cells

Insulin secretion from the β-cells of the islets of Langerhans is triggered mainly by nutrients such as glucose, and incretin hormones such as glucagon-like peptide-1 (GLP-1). The mechanisms of the stimulus-secretion coupling involve the participation of the key enzymes that metabolize the nutrients, and numerous ion channels that mediate the electrical activity. Several members of the transient receptor potential (TRP) channels participate in the processes that mediate the electrical activities and Ca2+ oscillations in these cells. Human β-cells express TRPC1, TRPM2, TRPM3, TRPM4, TRPM7, TRPP1, TRPML1, and TRPML3 channels. Some of these channels have been reported to mediate background depolarizing currents, store-operated Ca2+ entry (SOCE), electrical activity, Ca2+ oscillations, gene transcription, cell-death, and insulin secretion in response to stimulation by glucose and GLP1. Different channels of the TRP family are regulated by one or more of the following mechanisms: activation of G protein-coupled receptors, the filling state of the endoplasmic reticulum Ca2+ store, heat, oxidative stress, or some second messengers. This review briefly compiles our current knowledge about the molecular mechanisms of regulations, and functions of the TRP channels in the β-cells, the α-cells, and some insulinoma cell lines.

scholarly journals The Role of Transient Receptor Potential (TRP) Channels in the Transduction of Dental Pain

2019 ◽  
Vol 20 (3) ◽  
pp. 526 ◽  
Author(s):  
Mohammad Hossain ◽  
Marina Bakri ◽  
Farhana Yahya ◽  
Hiroshi Ando ◽  
Shumpei Unno ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Transient Receptor Potential ◽  
Trp Channels ◽  
Glutamate Release ◽  
Receptor Potential ◽  
Functional Expression ◽  
Dental Pain ◽  
Post Translational Modifications ◽  
Transient Receptor ◽  
External Stimuli

Dental pain is a common health problem that negatively impacts the activities of daily living. Dentine hypersensitivity and pulpitis-associated pain are among the most common types of dental pain. Patients with these conditions feel pain upon exposure of the affected tooth to various external stimuli. However, the molecular mechanisms underlying dental pain, especially the transduction of external stimuli to electrical signals in the nerve, remain unclear. Numerous ion channels and receptors localized in the dental primary afferent neurons (DPAs) and odontoblasts have been implicated in the transduction of dental pain, and functional expression of various polymodal transient receptor potential (TRP) channels has been detected in DPAs and odontoblasts. External stimuli-induced dentinal tubular fluid movement can activate TRP channels on DPAs and odontoblasts. The odontoblasts can in turn activate the DPAs by paracrine signaling through ATP and glutamate release. In pulpitis, inflammatory mediators may sensitize the DPAs. They could also induce post-translational modifications of TRP channels, increase trafficking of these channels to nerve terminals, and increase the sensitivity of these channels to stimuli. Additionally, in caries-induced pulpitis, bacterial products can directly activate TRP channels on DPAs. In this review, we provide an overview of the TRP channels expressed in the various tooth structures, and we discuss their involvement in the development of dental pain.

Ca2+ pathway involved in the refilling of store sites in rat adrenal medullary cells

2009 ◽  
Vol 296 (4) ◽  
pp. C889-C899 ◽  
Author(s):  
Hidetada Matsuoka ◽  
Keita Harada ◽  
Tomoya Ikeda ◽  
Kouta Uetsuki ◽  
Takeyoshi Sata ◽  
...  
Keyword(s):  
Transient Receptor Potential ◽  
Outward Current ◽  
Receptor Potential ◽  
Transient Receptor Potential Channels ◽  
Experimental Result ◽  
Intracellular Ca ◽  
Serca Pump ◽  
Potential Channels ◽  
Trpc1 Channels ◽  
Transient Receptor

It has been suggested that store-operated Ca2+ entry (SOC) facilitates catecholamine secretion and synthesis in bovine adrenal medullary (AM) cells. However, there has been no experimental result clearly showing that cation channel activity is enhanced by store Ca2+ depletion. Thus the present experiments were undertaken to address the issue of whether rat AM cells have SOC channels. Inhibition of the sarco(endo)plasmic reticulum Ca2+ (SERCA) pump resulted in a sustained increase in intracellular Ca2+ concentration ([Ca2+]i) in rat AM cells. This increase was completely suppressed by 2 mM Ni2+ but not by 100 μM D600. A bath application of Ni2+, but not D600, produced an outward current at −60 mV in rat AM cells, whereas exposure to a SERCA pump inhibitor did not affect either the whole cell current level or the Ni2+-induced outward current. The refilling of intracellular store sites was suppressed by the addition of Ni2+ to the perfusate. RT-PCR revealed that transcripts for transient receptor potential channels 1 (TRPC1) and 5 (TRPC5) were present in rat adrenal medullas. Immunocytochemistry showed that TRPC1 channels, which have been implicated in SOC in certain types of cells, were mainly localized in the endoplasmic reticulum (ER) and not in the plasma membrane, and that STIM1, a Ca2+ sensor in the ER, was not expressed in rat AM cells. On the basis of these results, we conclude that rat AM cells lack the SOC mechanism.

scholarly journals The Xenopus tropicalis orthologue of TRPV3 is heat sensitive

2015 ◽  
Vol 146 (5) ◽  
pp. 411-421 ◽  
Author(s):  
Beiying Liu ◽  
Feng Qin
Keyword(s):  
Mammalian Cells ◽  
Xenopus Oocytes ◽  
Transient Receptor Potential ◽  
Trp Channels ◽  
Expression System ◽  
Receptor Potential ◽  
Functional Expression ◽  
Cold Sensitivity ◽  
Mammalian Cell Lines ◽  
Transient Receptor

Thermosensitive members of the transient receptor potential (TRP) family of ion channels (thermal TRP channels) play a crucial role in mammalian temperature sensing. Orthologues of these channels are present in lower vertebrates and, remarkably, some thermal TRP orthologues from different species appear to mediate opposing responses to temperature. For example, whereas the mammalian TRPV3 channel is activated by heat, frog TRPV3 is reportedly activated by cold. Intrigued by the potential implications of these opposing responses to temperature for the mechanism of temperature-dependent gating, we cloned Xenopus laevis TRPV3 and functionally expressed it in both mammalian cell lines and Xenopus oocytes. We found that, when expressed in mammalian cells, the recombinant channel lacks the reported cold sensitivity; rather, it is activated by temperatures >50°C. Furthermore, when expressed in mammalian cells, the frog orthologue shows other features characteristic of mammalian TRPV3, including activation by the agonist 2-aminoethoxydiphenyl borate and an increased response with repeated stimulation. We detected both heat- and cold-activated currents in Xenopus oocytes expressing the recombinant frog TRPV3 channel. However, cold-activated currents were also apparent in control oocytes lacking recombinant TRPV3. Our data indicate that frog TRPV3 resembles its mammalian orthologues in terms of its thermosensitivity and is intrinsically activated by heat. Thus, all known vanilloid receptors are activated by heat. Our data also show that Xenopus oocytes contain endogenous receptors that are activated by cold, and suggest that cold sensitivity of TRP channels established using Xenopus oocytes as a functional expression system may need to be revisited.

Transient receptor potential channels and vascular function

2010 ◽  
Vol 119 (1) ◽  
pp. 19-36 ◽  
Author(s):  
Scott Earley ◽  
Joseph E. Brayden
Keyword(s):  
Vascular Function ◽  
Transient Receptor Potential ◽  
Trp Channels ◽  
Receptor Potential ◽  
Receptor Activation ◽  
Transient Receptor Potential Channels ◽  
No Production ◽  
Control Mechanisms ◽  
Potential Channels ◽  
Transient Receptor

TRP (transient receptor potential) channels play important roles in the regulation of normal and pathological cellular function. In the vasculature, TRP channels are present both in ECs (endothelial cells) and vascular SMCs (smooth muscle cells) and contribute to vasomotor control mechanisms in most vascular beds. Vascular TRP channels are activated by various stimuli, such as mechanical perturbation, receptor activation and dietary molecules. Some of the specific roles of these channels in normal and impaired vascular function have emerged in recent years and include participation in vascular signalling processes, such as neurotransmission, hormonal signalling, NO production, myogenic tone and autoregulation of blood flow, thermoregulation, responses to oxidative stress and cellular proliferative activity. Current research is aimed at understanding the interactions of TRP channels with other vascular proteins and signalling mechanisms. These studies should reveal new targets for pharmacological therapy of vascular diseases, such as hypertension, ischaemia and vasospasm, and vascular proliferative states.

scholarly journals Calcium signaling through a Transient Receptor Channel is important for Toxoplasma gondii growth

2020 ◽  
Author(s):  
Karla M. Márquez-Nogueras ◽  
Nathan M. Chasen ◽  
Myriam A. Hortua Triana ◽  
Ivana Y. Kuo ◽  
Silvia N.J. Moreno
Keyword(s):  
Toxoplasma Gondii ◽  
Transient Receptor Potential ◽  
Trp Channels ◽  
Functional Characterization ◽  
Receptor Potential ◽  
Nuclear Membranes ◽  
Intracellular Ca ◽  
Transient Receptor ◽  
Stimulation Of ◽  
Receptor Channel

ABSTRACTTransient Receptor Potential (TRP) channels participate in ion calcium (Ca2+) influx and intracellular Ca2+ release. TRP channels have not been studied in Toxoplasma gondii or any other Apicomplexan parasite. We characterized a protein predicted to possess a TRP domain (TgTRPPL-2) and determined its role in Ca2+ signaling in T. gondii, the causative agent of toxoplasmosis. TgTRPPL-2 localized to the plasma membrane and the endoplasmic reticulum of T. gondii. The ΔTgTRPPL-2 mutant was defective in growth and Ca2+ influx. Heterologous expression of TgTRPPL-2 in HEK-3KO cells allowed its functional characterization. Patching of ER-nuclear membranes demonstrated that TgTRPPL-2 is a non-selective cation channel that conducts Ca2+. Pharmacological blockers of TgTRPPL-2 inhibited Ca2+ influx and parasite growth. This is the first report of an Apicomplexan channel that conducts Ca2+ and initiates the Ca2+ signaling cascade that culminates in the stimulation of motility, invasion and egress. TgTRPPL-2 is a potential target for combating toxoplasmosis.

scholarly journals Does serotonin deficiency lead to anosmia, ageusia and dysfunctional chemesthesis in COVID-19?

2021 ◽  
Author(s):  
Amarnath Sen
Keyword(s):  
Selective Serotonin Reuptake Inhibitors ◽  
Transient Receptor Potential ◽  
Trp Channels ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
Taste Receptor ◽  
Receptor Potential ◽  
Transient Receptor Potential Channels ◽  
Host Cells ◽  
Potential Channels ◽  
Transient Receptor

Anosmia, ageusia and impaired chemesthetic sensations are quite common in coronavirus patients. Different mechanisms have been proposed to explain the anosmia and ageusia of COVID-19 patients, though for reversible anosmia and ageusia, which are resolved quickly, the proposed mechanisms seem to be incomplete. In addition, the reason behind the impaired chemesthetic sensations of some coronavirus patients remains unknown. It is proposed that in coronavirus patients, there is depletion of tryptophan (an essential amino acid), as ACE2, a key element in the process of absorption of tryptophan from food, is significantly reduced due to the attack of coronavirus which use ACE2 as the receptor for its entry into the host cells. Incidentally, the depletion of tryptophan should lead to deficiency of serotonin (5-HT) in SARS-COV-2 patients because tryptophan is the precursor in the synthesis of 5-HT. Such 5-HT deficiency not only explains fast resolved anosmia and ageusia, but also dysfunctional chemesthesis, given the fact that 5-HT is an important neuromodulator in the olfactory neurons and taste receptor cells and 5-HT also enhances the nociceptor activity of transient receptor potential channels (TRP channels) responsible for chemesthetic sensations. The female predominance of olfactory and gustatory dysfunctions can also be explained by considering low 5-HT levels in women. In addition, 5-HT deficiency worsens silent hypoxemia and explains why hypoxic pulmonary vasoconstriction is nearly absent in coronavirus patients leading to poor outcome. Hence, clinical trials should be conducted on coronavirus patients to find out how different selective serotonin reuptake inhibitors (SSRIs) and serotonin agonists work out in eliminating or improving the olfactory, gustatory and chemesthetic dysfunctions as well as hypoxemia.

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