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Cai MJ, Dong DJ, Wang Y, Liu PC, Liu W, Wang JX, Zhao XF. G-protein-coupled receptor participates in 20-hydroxyecdysone signaling on the plasma membrane. Cell Commun Signal 2014; 12:9. [PMID: 24507557 PMCID: PMC3937218 DOI: 10.1186/1478-811x-12-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Accepted: 02/03/2014] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND Animal steroid hormones are conventionally known to initiate signaling via a genomic pathway by binding to the nuclear receptors. The mechanism by which 20E initiates signaling via a nongenomic pathway is unclear. RESULTS We illustrate that 20E triggered the nongenomic pathway through a plasma membrane G-protein-coupled receptor (named ErGPCR) in the lepidopteran insect Helicoverpa armigera. The transcript of ErGPCR was increased at the larval molting stage and metamorphic molting stage by 20E regulation. Knockdown of ErGPCR via RNA interference in vivo blocked larval-pupal transition and suppressed 20E-induced gene expression. ErGPCR overexpression in the H. armigera epidermal cell line increased the 20E-induced gene expression. Through ErGPCR, 20E modulated Calponin nuclear translocation and phosphorylation, and induced a rapid increase in cytosolic Ca2+ levels. The inhibitors of T-type voltage-gated calcium channels and canonical transient receptor potential calcium channels repressed the 20E-induced Ca2+ increase. Truncation of the N-terminal extracellular region of ErGPCR inhibited its localization on the plasma membrane and 20E-induced gene expression. ErGPCR was not detected to bind with the steroid hormone analog [3H]Pon A. CONCLUSION These results suggest that ErGPCR participates in 20E signaling on the plasma membrane.
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Affiliation(s)
- Mei-Juan Cai
- The Key Laboratory of Plant Cell Engineering and Germplasm Innovation, Ministry of Education, Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Jinan 250100, Shandong, China
| | - Du-Juan Dong
- The Key Laboratory of Plant Cell Engineering and Germplasm Innovation, Ministry of Education, Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Jinan 250100, Shandong, China
| | - Yu Wang
- The Key Laboratory of Plant Cell Engineering and Germplasm Innovation, Ministry of Education, Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Jinan 250100, Shandong, China
| | - Peng-Cheng Liu
- The Key Laboratory of Plant Cell Engineering and Germplasm Innovation, Ministry of Education, Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Jinan 250100, Shandong, China
| | - Wen Liu
- The Key Laboratory of Plant Cell Engineering and Germplasm Innovation, Ministry of Education, Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Jinan 250100, Shandong, China
| | - Jin-Xing Wang
- The Key Laboratory of Plant Cell Engineering and Germplasm Innovation, Ministry of Education, Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Jinan 250100, Shandong, China
| | - Xiao-Fan Zhao
- The Key Laboratory of Plant Cell Engineering and Germplasm Innovation, Ministry of Education, Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Jinan 250100, Shandong, China
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203
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Fenwick AJ, Wu SW, Peters JH. Isolation of TRPV1 independent mechanisms of spontaneous and asynchronous glutamate release at primary afferent to NTS synapses. Front Neurosci 2014; 8:6. [PMID: 24550768 PMCID: PMC3907708 DOI: 10.3389/fnins.2014.00006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Accepted: 01/09/2014] [Indexed: 01/31/2023] Open
Abstract
Cranial visceral afferents contained within the solitary tract (ST) contact second-order neurons in the nucleus of the solitary tract (NTS) and release the excitatory amino acid glutamate via three distinct exocytosis pathways; synchronous, asynchronous, and spontaneous release. The presence of TRPV1 in the central terminals of a majority of ST afferents conveys activity-dependent asynchronous glutamate release and provides a temperature sensitive calcium conductance which largely determines the rate of spontaneous vesicle fusion. TRPV1 is present in unmyelinated C-fiber afferents and these facilitated forms of glutamate release may underlie the relative strength of C-fibers in activating autonomic reflex pathways. However, pharmacological blockade of TRPV1 signaling eliminates only ~50% of the asynchronous profile and attenuates the temperature sensitivity of spontaneous release indicating additional thermosensitive calcium influx pathways may exist which mediate these forms of vesicle release. In the present study we isolate the contribution of TRPV1 independent forms of glutamate release at ST-NTS synapses. We found ST afferent innervation at NTS neurons and synchronous vesicle release from TRPV1 KO mice was not different to control animals; however, only half of TRPV1 KO ST afferents completely lacked asynchronous glutamate release. Further, temperature driven spontaneous rates of vesicle release were not different from 33 to 37°C between control and TRPV1 KO afferents. These findings suggest additional temperature dependent mechanisms controlling asynchronous and thermosensitive spontaneous release at physiological temperatures, possibly mediated by additional thermosensitive TRP channels in primary afferent terminals.
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Affiliation(s)
- Axel J Fenwick
- Department of Integrative Physiology and Neuroscience, Washington State University Pullman, WA, USA
| | - Shaw-Wen Wu
- Department of Integrative Physiology and Neuroscience, Washington State University Pullman, WA, USA
| | - James H Peters
- Department of Integrative Physiology and Neuroscience, Washington State University Pullman, WA, USA
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204
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Opening of an alternative ion permeation pathway in a nociceptor TRP channel. Nat Chem Biol 2014; 10:188-95. [DOI: 10.1038/nchembio.1428] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Accepted: 11/04/2013] [Indexed: 11/08/2022]
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205
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Abstract
Drug-like compounds that exert biological activity towards TRP channels are either being used as cell biological tools or further developed into pharmacological lead structures aiming at therapeutic use in diseased states. Although drug-likeliness is not easy to predict, common rules include a relatively low molecular weight, physicochemical constraints, and the absence of known reactive or otherwise toxic groups. Small molecules that exert a biological activity to block, activate, or modulate TRP channels are intensely sought. Such tool compounds may be useful to assign native currents to a certain TRP channel and to validate the channel as a candidate target for future pharmacological intervention. Depending on the TRP channel isotype, these activities have reached different levels, with only few TRP channels modulators already being clinically tested in humans, whereas other compounds only underwent a preliminary validation. For some TRP channels, reliable low molecular weight inhibitors are not yet available. Hence, further efforts need to be undertaken in order to explore the physiological impact and possible therapeutic potential of TRP channel targeting with drug-like compounds.
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Affiliation(s)
- Michael Schaefer
- Rudolf-Boehm-Institut für Pharmakologie und Toxikologie, Härtelstraße 16-18, 04107, Leipzig, Germany,
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206
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Abstract
The use of medicinal plants or other naturally derived products to relieve illness can be traced back over several millennia, and these natural products are still extensively used nowadays. Studies on natural products have, over the years, enormously contributed to the development of therapeutic drugs used in modern medicine. By means of the use of these substances as selective agonists, antagonists, enzyme inhibitors or activators, it has been possible to understand the complex function of many relevant targets. For instance, in an attempt to understand how pepper species evoke hot and painful actions, the pungent and active constituent capsaicin (from Capsicum sp.) was isolated in 1846 and the receptor for the biological actions of capsaicin was cloned in 1997, which is now known as TRPV1 (transient receptor potential vanilloid 1). Thus, TRPV1 agonists and antagonists have currently been tested in order to find new drug classes to treat different disorders. Indeed, the transient receptor potential (TRP) proteins are targets for several natural compounds, and antagonists of TRPs have been synthesised based on the knowledge of naturally derived products. In this context, this chapter focuses on naturally derived compounds (from plants and animals) that are reported to be able to modulate TRP channels. To clarify and make the understanding of the modulatory effects of natural compounds on TRPs easier, this chapter is divided into groups according to TRP subfamilies: TRPV (TRP vanilloid), TRPA (TRP ankyrin), TRPM (TRP melastatin), TRPC (TRP canonical) and TRPP (TRP polycystin). A general overview on the naturally derived compounds that modulate TRPs is depicted in Table 1.
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Affiliation(s)
- Flavia Carla Meotti
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, 05508-000, São Paulo, SP, Brazil
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207
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Abstract
Transient receptor potential (TRP) ion channels have been detected in neurons that are part of the neural network controlling reproductive physiology and behavior. In this chapter we will primarily take a look at the classical/canonical TRP (TRPC) channels but will also examine some other members of the TRP channel superfamily in reproductive (neuro)endocrinology. The referenced data suggest that different TRP proteins could play functional roles at different levels of the reproductive pathway. Still, our understanding of TRP channel involvement in (neuro)endocrinology is quite limited. Due to their mechanism of activation and complex regulation, these channels are however ideally suited to be part of the transduction machinery of hormone-secreting cells.
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Affiliation(s)
- Trese Leinders-Zufall
- Department of Physiology, University of Saarland School of Medicine, 66421, Homburg, Germany,
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208
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Vejrazkova D, Vcelak J, Vankova M, Lukasova P, Bradnova O, Halkova T, Kancheva R, Bendlova B. Steroids and insulin resistance in pregnancy. J Steroid Biochem Mol Biol 2014. [PMID: 23202146 DOI: 10.1016/j.jsbmb.2012.11.007] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Metabolism of glucose during pregnancy reflects the equilibrium between lactogenic hormones stimulating insulin production and counterregulatory hormones inducing insulin resistance. In physiological pregnancies, insulin-mediated glucose uptake is substantially decreased and insulin secretion increased to maintain euglycemia. This common state of peripheral insulin resistance arises also due to steroid spectra changes. In this review article, we have focused on the role of steroid hormones (androgens, estrogens, gestagens, mineralocorticoids, glucocorticoids, as well as secosteroid vitamin D) in the impairment of glucose tolerance in pregnancy and in the pathogenesis of gestational diabetes mellitus. This article is part of a Special Issue entitled 'Pregnancy and Steroids'.
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209
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Abstract
Like most other members of the TRP family, the Trpm3 gene encodes proteins that form cation-permeable ion channels on the plasma membrane. However, TRPM3 proteins have several unique features that set them apart from the other members of this diverse family. The Trpm3 gene encodes for a surprisingly large number of isoforms generated mainly by alternative splicing. Only for two of the (at least) eight sites at which sequence diversity is generated the functional consequences have been elucidated, one leading to nonfunctional channels, the other one profoundly affecting the ionic selectivity. In the Trpm3 gene an intronic microRNA (miR-204) is co-transcribed with Trpm3. By regulating the expression of a multitude of genes, miR-204 increases the functional complexity of the Trpm3 locus. Over the past years, important progress has been made in discovering pharmacological tools to manipulate TRPM3 channel activity. These substances have facilitated the identification of endogenously expressed functional TRPM3 channels in nociceptive neurons, pancreatic beta cells, and vascular smooth muscle cells, among others. TRPM3 channels, which themselves are temperature sensitive, thus have been implicated in sensing noxious heat, in modulating insulin release, and in secretion of inflammatory cytokines. However, in many tissues where TRPM3 proteins are known to be expressed, no functional role has been identified for these channels so far. Because of the availability of adequate pharmacological and genetic tools, it is expected that future investigations on TRPM3 channels will unravel important new aspects and functions of these channels.
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Affiliation(s)
- Johannes Oberwinkler
- Institut für Physiologie und Pathophysiologie, Philipps-Universität Marburg, 35037, Marburg, Germany,
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210
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Baez D, Raddatz N, Ferreira G, Gonzalez C, Latorre R. Gating of thermally activated channels. CURRENT TOPICS IN MEMBRANES 2014; 74:51-87. [PMID: 25366233 DOI: 10.1016/b978-0-12-800181-3.00003-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
A class of ion channels that belongs to the transient receptor potential (TRP) superfamily and is present in specialized neurons that project to the skin has evolved as temperature detectors. These channels are classified into subfamilies, namely canonical (TRPC), melastatin (TRPM), ankyrin (TRPA), and vanilloid (TRPV). Some of these channels are activated by heat (TRPM2/4/5, TRPV1-4), while others by cold (TRPA1, TRPC5, and TRPM8). The general structure of these channels is closely related to that of the voltage-dependent K(+) channels, with their subunits containing six transmembrane segments that form tetramers. Thermal TRP channels are polymodal receptors. That is, they can be activated by temperature, voltage, pH, lipids, and agonists. The high temperature sensitivity in these thermal TRP channels is due to a large enthalpy change (∼100 kcal/mol), which is about five times the enthalpy change in voltage-dependent gating. The characterization of the macroscopic currents and single-channel analysis demonstrated that gating by temperature is complex and best described by branched or allosteric models containing several closed and open states. The identification of molecular determinants of temperature sensitivity in TRPV1, TRPA1, and TRPV3 strongly suggest that thermal sensitivity arises from a specific protein domain.
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Affiliation(s)
- David Baez
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Natalia Raddatz
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile; Centre for Plant Biotechnology and Genomics, Universidad Politécnica de Madrid, Pozuelo de Alarcón (Madrid), Spain
| | - Gonzalo Ferreira
- Laboratorio de Canales Iónicos, Departamento de Biofísica, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - Carlos Gonzalez
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Ramon Latorre
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
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211
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Abstract
Pain usually occurs as a result of tissue damage and has a role in healing and protection. However, in certain conditions it has no functional purpose and can become chronic and debilitating. A demand for more effective treatments to deal with this highly prevalent problem requires a better understanding of the underlying mechanisms. TRP channels are associated with numerous sensory functions across a wide range of species. Investigation into the expression patterns, electrophysiological properties and the effects of channel deletion in transgenic animal models have produced a great deal of evidence linking these channels to transduction of noxious stimuli as well as signalling within the pain system.
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Affiliation(s)
- Jane E Sexton
- Molecular Nociception Group, Wolfson Institute for Biomedical Research, University College London, London, WC1E 6BT, UK,
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212
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Hiriart M, Velasco M, Larqué C, Diaz-Garcia CM. Metabolic Syndrome and Ionic Channels in Pancreatic Beta Cells. THE PANCREATIC BETA CELL 2014; 95:87-114. [DOI: 10.1016/b978-0-12-800174-5.00004-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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213
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Alexander SPH, Benson HE, Faccenda E, Pawson AJ, Sharman JL, Catterall WA, Spedding M, Peters JA, Harmar AJ. The Concise Guide to PHARMACOLOGY 2013/14: ion channels. Br J Pharmacol 2013; 170:1607-51. [PMID: 24528239 PMCID: PMC3892289 DOI: 10.1111/bph.12447] [Citation(s) in RCA: 224] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The Concise Guide to PHARMACOLOGY 2013/14 provides concise overviews of the key properties of over 2000 human drug targets with their pharmacology, plus links to an open access knowledgebase of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. The full contents can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.12444/full. Ion channels are one of the seven major pharmacological targets into which the Guide is divided, with the others being G protein-coupled receptors, ligand-gated ion channels, catalytic receptors, nuclear hormone receptors, transporters and enzymes. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. A new landscape format has easy to use tables comparing related targets. It is a condensed version of material contemporary to late 2013, which is presented in greater detail and constantly updated on the website www.guidetopharmacology.org, superseding data presented in previous Guides to Receptors and Channels. It is produced in conjunction with NC-IUPHAR and provides the official IUPHAR classification and nomenclature for human drug targets, where appropriate. It consolidates information previously curated and displayed separately in IUPHAR-DB and the Guide to Receptors and Channels, providing a permanent, citable, point-in-time record that will survive database updates.
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Affiliation(s)
- Stephen PH Alexander
- School of Life Sciences, University of Nottingham Medical SchoolNottingham, NG7 2UH, UK
- *
Author for correspondence;
| | - Helen E Benson
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Elena Faccenda
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Adam J Pawson
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Joanna L Sharman
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - William A Catterall
- University of Washington, School of Medicine, Department of PharmacologyBox 357280, Seattle, WA 98195-7280, USA
| | | | - John A Peters
- Neuroscience Division, Medical Education Institute, Ninewells Hospital and Medical School, University of DundeeDundee, DD1 9SY, UK
| | - Anthony J Harmar
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
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214
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Abstract
TRP channels constitute a large superfamily of cation channel forming proteins, all related to the gene product of the transient receptor potential (trp) locus in Drosophila. In mammals, 28 different TRP channel genes have been identified, which exhibit a large variety of functional properties and play diverse cellular and physiological roles. In this article, we provide a brief and systematic summary of expression, function, and (patho)physiological role of the mammalian TRP channels.
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Affiliation(s)
- Maarten Gees
- Laboratory Ion Channel Research and TRP Research Platform Leuven (TRPLe), KU Leuven, Campus Gasthuisberg, Leuven, Belgium
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215
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Pregnenolone sulfate: from steroid metabolite to TRP channel ligand. Molecules 2013; 18:12012-28. [PMID: 24084011 PMCID: PMC6270300 DOI: 10.3390/molecules181012012] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2013] [Revised: 09/20/2013] [Accepted: 09/21/2013] [Indexed: 01/16/2023] Open
Abstract
Pregnenolone sulfate is a steroid metabolite with a plethora of actions and functions. As a neurosteroid, pregnenolone sulfate modulates a variety of ion channels, transporters, and enzymes. Interestingly, as a sulfated steroid, pregnenolone sulfate is not the final- or waste-product of pregnenolone being sulfated via a phase II metabolism reaction and renally excreted, as one would presume from the pharmacology textbook knowledge. Pregnenolone sulfate is also the source and thereby the starting point for subsequent steroid synthesis pathways. Most recently, pregnenolone sulfate has been functionally “upgraded” from modulator of ion channels to an activating ion channel ligand. This review will focus on molecular aspects of the neurosteroid, pregnenolone sulfate, its metabolism, concentrations in serum and tissues and last not least will summarize the functional data.
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216
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Alpizar YA, Sanchez A, Radwan A, Radwan I, Voets T, Talavera K. Lack of correlation between the amplitudes of TRP channel-mediated responses to weak and strong stimuli in intracellular Ca(2+) imaging experiments. Cell Calcium 2013; 54:362-74. [PMID: 24079971 DOI: 10.1016/j.ceca.2013.08.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2013] [Revised: 08/29/2013] [Accepted: 08/31/2013] [Indexed: 01/18/2023]
Abstract
It is often observed in intracellular Ca(2+) imaging experiments that the amplitudes of the Ca(2+) signals elicited by newly characterized TRP agonists do not correlate with the amplitudes of the responses evoked subsequently by a specific potent agonist. We investigated this rather controversial phenomenon by first testing whether it is inherent to the comparison of the effects of weak and strong stimuli. Using five well-characterized TRP channel agonists in commonly used heterologous expression systems we found that the correlation between the amplitudes of the Ca(2+) signals triggered by two sequentially applied stimuli is only high when both stimuli are strong. Using mathematical simulations of intracellular Ca(2+) dynamics we illustrate that the innate heterogeneity in expression and functional properties of Ca(2+) extrusion (e.g. plasma membrane Ca(2+) ATPase) and influx (TRP channels) pathways across a cellular population is a sufficient condition for low correlation between the amplitude of Ca(2+) signals elicited by weak and strong stimuli. Taken together, our data demonstrate that this phenomenon is an expected outcome of intracellular Ca(2+) imaging experiments that cannot be taken as evidence for lack of specificity of low-efficacy stimuli, or as an indicator of the need of other cellular components for channel stimulation.
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Affiliation(s)
- Yeranddy A Alpizar
- Laboratory for Ion Channel Research and TRP Research Platform Leuven (TRPLe), Department of Molecular Cell Biology, KU Leuven, Belgium
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217
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Straub I, Krügel U, Mohr F, Teichert J, Rizun O, Konrad M, Oberwinkler J, Schaefer M. Flavanones that selectively inhibit TRPM3 attenuate thermal nociception in vivo. Mol Pharmacol 2013; 84:736-50. [PMID: 24006495 DOI: 10.1124/mol.113.086843] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Transient receptor potential melastatin 3 (TRPM3) is a calcium-permeable nonselective cation channel that is expressed in a subset of dorsal root (DRG) and trigeminal ganglia sensory neurons. TRPM3 can be activated by the neurosteroid pregnenolone sulfate (PregS) and heat. TRPM3⁻/⁻ mice display an impaired sensation of noxious heat and thermal hyperalgesia. We have previously shown that TRPM3 is blocked by the citrus fruit flavanones hesperetin, naringenin, and eriodictyol as well as by ononetin, a deoxybenzoin from Ononis spinosa. To further improve the tolerability, potency, and selectivity of TRPM3 blockers, we conducted a hit optimization procedure by rescreening a focused library that was composed of chemically related compounds. Within newly identified TRPM3 blockers, isosakuranetin and liquiritigenin displayed favorable properties with respect to their inhibitory potency and a selective mode of action. Isosakuranetin, a flavanone whose glycoside is contained in blood oranges and grapefruits, displayed an IC₅₀ of 50 nM and is to our knowledge the most potent inhibitor of TRPM3 identified so far. Both compounds exhibited a marked specificity for TRPM3 compared with other sensory TRP channels, and blocked PregS-induced intracellular free Ca²⁺ concentration signals and ionic currents in freshly isolated DRG neurons. Furthermore, isosakuranetin and previously identified hesperetin significantly reduced the sensitivity of mice to noxious heat and PregS-induced chemical pain. Because the physiologic functions of TRPM3 channels are still poorly defined, the development and validation of potent and selective blockers is expected to contribute to clarifying the role of TRPM3 in vivo.
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Affiliation(s)
- Isabelle Straub
- Rudolf-Boehm-Institut für Pharmakologie und Toxikologie, Universität Leipzig, Leipzig, Germany (I.S., U.K., J.T., M.S.); and Institut für Physiologie und Pathophysiologie, Philipps-Universität Marburg, Marburg, Germany (F.M., O.R., M.K., J.O.)
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218
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Benemei S, De Cesaris F, Fusi C, Rossi E, Lupi C, Geppetti P. TRPA1 and other TRP channels in migraine. J Headache Pain 2013; 14:71. [PMID: 23941062 PMCID: PMC3844362 DOI: 10.1186/1129-2377-14-71] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Accepted: 08/10/2013] [Indexed: 12/26/2022] Open
Abstract
Ever since their identification, interest in the role of transient receptor potential (TRP) channels in health and disease has steadily increased. Robust evidence has underlined the role of TRP channels expressed in a subset of primary sensory neurons of the trigeminal ganglion to promote, by neuronal excitation, nociceptive responses, allodynia and hyperalgesia. In particular, the TRP vanilloid 1 (TRPV1) and the TRP ankyrin 1 (TRPA1) are expressed in nociceptive neurons, which also express the sensory neuropeptides, tachykinins, and calcitonin gene-related peptide (CGRP), which mediate neurogenic inflammatory responses. Of interest, CGRP released from the trigeminovascular network of neurons is currently recognized as a main contributing mechanism of migraine attack. The ability of TRPA1 to sense and to be activated by an unprecedented series of exogenous and endogenous reactive molecules has now been extensively documented. Several of the TRPA1 activators are also known as triggers of migraine attack. Thus, TRP channels, and particularly TRPA1, may be proposed as novel pathways in migraine pathophysiology and as possible new targets for its treatment.
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Affiliation(s)
- Silvia Benemei
- Headache Center and Clinical Pharmacology Unit, Department of Health Sciences, Careggi University Hospital, University of Florence, viale Pieraccini 6, Florence 50139, Italy.
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219
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Abstract
Transient receptor potential melastatin 3 (TRPM3) channels are non-selective cation channels that are expressed in insulinoma cells and pancreatic β-cells. Stimulation of TRPM3 with the neurosteroid pregnenolone sulfate induces an intracellular signaling cascade, involving a rise in intracellular Ca(2)(+) concentration, activation of the protein kinases Raf and ERK, and a change in the gene expression pattern of the cells. In particular, biosynthesis of insulin is altered following activation of TRPM3 by pregnenolone sulfate. Moreover, a direct effect of TRPM3 stimulation on insulin secretion has been reported. The fact that stimulation of TRPM3 induces a signaling cascade that is very similar to the signaling cascade induced by glucose in β-cells suggests that TRPM3 may influence main functions of pancreatic β-cells. The view that TRPM3 represents an ionotropic steroid receptor of pancreatic β-cells linking insulin release with steroid hormone signaling is discussed.
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Affiliation(s)
- Gerald Thiel
- Department of Medical Biochemistry and Molecular Biology, University of Saarland Medical Center, Building 44, D-66421 Homburg, Germany.
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220
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Bouron A, Oberwinkler J. Contribution of calcium-conducting channels to the transport of zinc ions. Pflugers Arch 2013; 466:381-7. [PMID: 23719866 DOI: 10.1007/s00424-013-1295-z] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Revised: 05/10/2013] [Accepted: 05/10/2013] [Indexed: 10/26/2022]
Abstract
Zinc (Zn) is a vital nutrient participating in a myriad of biological processes. The mechanisms controlling its transport through the plasma membrane are far from being completely understood. Two families of eukaryotic zinc transporters are known to date: the Zip (SLC39) and ZnT (SLC30) proteins. In addition, some types of plasmalemmal calcium (Ca)-conducting channels are implied in the cellular uptake of zinc. These ion channels are currently described as systems dedicated to the transport of Ca (and, to some extent, sodium (Na) ions). However, a growing body of evidence supports the view that some of them can also function as pathways for Zn transport. For instance, voltage-gated Ca channels and some types of glutamate-gated receptors have long been known to allow the entry of Zn. More recently, members of the TRP superfamily, another type of Ca-conducting channels, have been shown to permit the uptake of Zn into eukaryotic cells. The aim of this review article is to present the current knowledge supporting the notion that Ca-conducting channels take part in the plasmalemmal transport of Zn.
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Pregnenolone sulfate modulates glycinergic transmission in rat medullary dorsal horn neurons. Eur J Pharmacol 2013; 712:30-8. [PMID: 23665111 DOI: 10.1016/j.ejphar.2013.04.039] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Revised: 04/19/2013] [Accepted: 04/26/2013] [Indexed: 11/20/2022]
Abstract
The neurosteroid pregnenolone sulfate (PS), a representative excitatory neuromodulator, has a variety of neuropharmacological actions, such as memory enhancement and convulsant effects. In this study, the effects of PS on glycinergic transmission, such as glycinergic spontaneous miniature inhibitory postsynaptic currents (mIPSCs), were investigated in acutely isolated medullary dorsal horn neurons by use of a conventional whole-cell patch-clamp technique. PS significantly increased the frequency but decreased the amplitude of glycinergic mIPSCs in a concentration-dependent manner. PS also accelerated the decay time constant of glycinergic mIPSCs. The PS-induced decrease in mIPSC amplitude was due to the direct postsynaptic inhibition of glycine receptors because PS inhibited the glycine-induced Cl(-) currents in a noncompetitive manner. The PS-induced increase in mIPSC frequency was not due to the activation of α7 nicotinic acetylcholine, NMDA, σ1 receptors and voltage-dependent Ca(2+) channels, which are known to be molecular targets of PS. On the other hand, the PS-induced increase in mIPSC frequency was completely attenuated either in the Ca(2+)-free external solution or in the presence of transient receptor potential (TRP) channel blockers, suggesting that PS elicits an increase in Ca(2+) concentration within glycinergic nerve terminals via the activation of putative TRP channels. The PS-mediated modulation of glycinergic synaptic transmission, such as the enhancement of presynaptic glycine release and direct inhibition of postsynaptic glycine receptors, might have a broad impact on the excitability of medullary dorsal horn neurons and therefore affect the processing of nociceptive transmission from orofacial tissues.
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Shaham O, Gueta K, Mor E, Oren-Giladi P, Grinberg D, Xie Q, Cvekl A, Shomron N, Davis N, Keydar-Prizant M, Raviv S, Pasmanik-Chor M, Bell RE, Levy C, Avellino R, Banfi S, Conte I, Ashery-Padan R. Pax6 regulates gene expression in the vertebrate lens through miR-204. PLoS Genet 2013; 9:e1003357. [PMID: 23516376 PMCID: PMC3597499 DOI: 10.1371/journal.pgen.1003357] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Accepted: 01/17/2013] [Indexed: 12/22/2022] Open
Abstract
During development, tissue-specific transcription factors regulate both protein-coding and non-coding genes to control differentiation. Recent studies have established a dual role for the transcription factor Pax6 as both an activator and repressor of gene expression in the eye, central nervous system, and pancreas. However, the molecular mechanism underlying the inhibitory activity of Pax6 is not fully understood. Here, we reveal that Trpm3 and the intronic microRNA gene miR-204 are co-regulated by Pax6 during eye development. miR-204 is probably the best known microRNA to function as a negative modulator of gene expression during eye development in vertebrates. Analysis of genes altered in mouse Pax6 mutants during lens development revealed significant over-representation of miR-204 targets among the genes up-regulated in the Pax6 mutant lens. A number of new targets of miR-204 were revealed, among them Sox11, a member of the SoxC family of pro-neuronal transcription factors, and an important regulator of eye development. Expression of Trpm/miR-204 and a few of its targets are also Pax6-dependent in medaka fish eyes. Collectively, this study identifies a novel evolutionarily conserved mechanism by which Pax6 controls the down-regulation of multiple genes through direct up-regulation of miR-204. The transcription factor Pax6 is reiteratively employed in space and time for the establishment of progenitor pools and the differentiation of neuronal and non-neuronal lineages of the CNS, pancreas, and eye. Execution of these diverse developmental programs depends on simultaneous activation and repression of gene networks functioning downstream of Pax6. MicroRNAs function as inhibitors of gene expression. Many microRNA genes are transcribed through common promoters of host genes. In this study, using wide-scale analysis of changes in gene expression following Pax6 deletion in the lens, we discover that Pax6 regulates the gene Trpm3 and its hosted microRNA, miR-204. We then show that miR-204 suppresses several target genes in the lens, notably the neuronal gene Sox11. Lastly, by conducting parallel experiments in the medaka fish, we show that Pax6 control of miR-204 and its target genes is evolutionarily conserved between mammals and fish, stressing the biological importance of this pathway. Pax6 regulation of miR-204 explains part of the complex, divergent inhibitory activity of Pax6 in ocular progenitor cells, which is required to establish and maintain the identity and function of ocular tissues.
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Affiliation(s)
- Ohad Shaham
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Karen Gueta
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Eyal Mor
- Department of Cell and Developmental Biology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Pazit Oren-Giladi
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Dina Grinberg
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Qing Xie
- Department of Genetics and Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Ales Cvekl
- Department of Genetics and Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Noam Shomron
- Department of Cell and Developmental Biology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Noa Davis
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Maya Keydar-Prizant
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Shaul Raviv
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Metsada Pasmanik-Chor
- Bioinformatics Unit, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Rachel E. Bell
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Carmit Levy
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | | | - Sandro Banfi
- Telethon Institute of Genetics and Medicine, Naples, Italy
- Medical Genetics, Department of Biochemistry, Biophysics and General Pathology, Second University of Naples, Naples, Italy
| | - Ivan Conte
- Telethon Institute of Genetics and Medicine, Naples, Italy
- * E-mail: (IC); (RA-P)
| | - Ruth Ashery-Padan
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
- * E-mail: (IC); (RA-P)
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Amer MS, McKeown L, Tumova S, Liu R, Seymour VAL, Wilson LA, Naylor J, Greenhalgh K, Hou B, Majeed Y, Turner P, Sedo A, O'Regan DJ, Li J, Bon RS, Porter KE, Beech DJ. Inhibition of endothelial cell Ca²⁺ entry and transient receptor potential channels by Sigma-1 receptor ligands. Br J Pharmacol 2013; 168:1445-55. [PMID: 23121507 PMCID: PMC3596649 DOI: 10.1111/bph.12041] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Accepted: 10/10/2012] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND AND PURPOSE The Sigma-1 receptor (Sig1R) impacts on calcium ion signalling and has a plethora of ligands. This study investigated Sig1R and its ligands in relation to endogenous calcium events of endothelial cells and transient receptor potential (TRP) channels. EXPERIMENTAL APPROACH Intracellular calcium and patch clamp measurements were made from human saphenous vein endothelial cells and HEK 293 cells expressing exogenous human TRPC5, TRPM2 or TRPM3. Sig1R ligands were applied and short interfering RNA was used to deplete Sig1R. TRP channels tagged with fluorescent proteins were used for subcellular localization studies. KEY RESULTS In endothelial cells, 10-100 μM of the Sig1R antagonist BD1063 inhibited sustained but not transient calcium responses evoked by histamine. The Sig1R agonist 4-IBP and related antagonist BD1047 were also inhibitory. The Sig1R agonist SKF10047 had no effect. Sustained calcium entry evoked by VEGF or hydrogen peroxide was also inhibited by BD1063, BD1047 or 4-IBP, but not SKF10047. 4-IBP, BD1047 and BD1063 inhibited TRPC5 or TRPM3, but not TRPM2. Inhibitory effects of BD1047 were rapid in onset and readily reversed on washout. SKF10047 inhibited TRPC5 but not TRPM3 or TRPM2. Depletion of Sig1R did not prevent the inhibitory actions of BD1063 or BD1047 and Sig1R did not co-localize with TRPC5 or TRPM3. CONCLUSIONS AND IMPLICATIONS The data suggest that two types of Sig1R ligand (BD1047/BD1063 and 4-IBP) are inhibitors of receptor- or chemically activated calcium entry channels, acting relatively directly and independently of the Sig1R. Chemical foundations for TRP channel inhibitors are suggested.
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Affiliation(s)
- Mohamed S Amer
- Multidisciplinary Cardiovascular Research Centre, University of LeedsLeeds, UK
- Faculty of Biological Sciences, University of LeedsLeeds, UK
- Clinical Physiology Department, Faculty of Medicine, Menoufiya UniversityMenoufiya, Egypt
| | - Lynn McKeown
- Multidisciplinary Cardiovascular Research Centre, University of LeedsLeeds, UK
- Faculty of Biological Sciences, University of LeedsLeeds, UK
| | - Sarka Tumova
- Multidisciplinary Cardiovascular Research Centre, University of LeedsLeeds, UK
- Faculty of Biological Sciences, University of LeedsLeeds, UK
| | - Ruifeng Liu
- Multidisciplinary Cardiovascular Research Centre, University of LeedsLeeds, UK
- Faculty of Biological Sciences, University of LeedsLeeds, UK
| | - Victoria AL Seymour
- Multidisciplinary Cardiovascular Research Centre, University of LeedsLeeds, UK
- Faculty of Biological Sciences, University of LeedsLeeds, UK
| | - Lesley A Wilson
- Multidisciplinary Cardiovascular Research Centre, University of LeedsLeeds, UK
- Faculty of Biological Sciences, University of LeedsLeeds, UK
| | - Jacqueline Naylor
- Multidisciplinary Cardiovascular Research Centre, University of LeedsLeeds, UK
- Faculty of Biological Sciences, University of LeedsLeeds, UK
| | - Katriona Greenhalgh
- Multidisciplinary Cardiovascular Research Centre, University of LeedsLeeds, UK
- Faculty of Biological Sciences, University of LeedsLeeds, UK
| | - Bing Hou
- Multidisciplinary Cardiovascular Research Centre, University of LeedsLeeds, UK
- Faculty of Biological Sciences, University of LeedsLeeds, UK
| | - Yasser Majeed
- Multidisciplinary Cardiovascular Research Centre, University of LeedsLeeds, UK
- Faculty of Biological Sciences, University of LeedsLeeds, UK
| | - Paul Turner
- Multidisciplinary Cardiovascular Research Centre, University of LeedsLeeds, UK
- Faculty of Biological Sciences, University of LeedsLeeds, UK
| | - Alicia Sedo
- Multidisciplinary Cardiovascular Research Centre, University of LeedsLeeds, UK
- Faculty of Biological Sciences, University of LeedsLeeds, UK
| | - David J O'Regan
- Department of Cardiac Surgery, Leeds General InfirmaryLeeds, UK
| | - Jing Li
- Multidisciplinary Cardiovascular Research Centre, University of LeedsLeeds, UK
- Faculty of Biological Sciences, University of LeedsLeeds, UK
| | - Robin S Bon
- Multidisciplinary Cardiovascular Research Centre, University of LeedsLeeds, UK
- School of Chemistry, University of LeedsLeeds, UK
| | - Karen E Porter
- Multidisciplinary Cardiovascular Research Centre, University of LeedsLeeds, UK
- Faculty of Medicine and Health, University of LeedsLeeds, UK
| | - David J Beech
- Multidisciplinary Cardiovascular Research Centre, University of LeedsLeeds, UK
- Faculty of Biological Sciences, University of LeedsLeeds, UK
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Abstract
For the regulation of beta-cell function ion channels are of outstanding importance. Beta cells are specialized to convert changes in blood glucose concentration to an adequate secretory response. To achieve this, nutrient-induced alterations of electrical activity are directly coupled to changes in insulin release. Consequently, determination and analysis of ion channel activity are important tools for the characterization of beta-cell (patho)physiology and for the investigation of drugs that influence insulin release. With implementation of the patch-clamp technique it has become possible to analyze ion currents in beta cells under various conditions (e.g., in intact cells or independent of cell metabolism, as whole-cell currents or on a single channel level). In addition, this method enables to combine ion current recordings with determination of membrane potential and exocytosis. This chapter introduces the basic principles of different patch-clamp configurations and focuses on experimental protocols for ion channel recordings in beta cells.
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Chubanov V, Mederos y Schnitzler M, Meißner M, Schäfer S, Abstiens K, Hofmann T, Gudermann T. Natural and synthetic modulators of SK (K(ca)2) potassium channels inhibit magnesium-dependent activity of the kinase-coupled cation channel TRPM7. Br J Pharmacol 2012; 166:1357-76. [PMID: 22242975 DOI: 10.1111/j.1476-5381.2012.01855.x] [Citation(s) in RCA: 111] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND AND PURPOSE Transient receptor potential cation channel subfamily M member 7 (TRPM7) is a bifunctional protein comprising a TRP ion channel segment linked to an α-type protein kinase domain. TRPM7 is essential for proliferation and cell growth. Up-regulation of TRPM7 function is involved in anoxic neuronal death, cardiac fibrosis and tumour cell proliferation. The goal of this work was to identify non-toxic inhibitors of the TRPM7 channel and to assess the effect of blocking endogenous TRPM7 currents on the phenotype of living cells. EXPERIMENTAL APPROACH We developed an aequorin bioluminescence-based assay of TRPM7 channel activity and performed a hypothesis-driven screen for inhibitors of the channel. The candidates identified were further assessed electrophysiologically and in cell biological experiments. KEY RESULTS TRPM7 currents were inhibited by modulators of small conductance Ca²⁺ -activated K⁺ channels (K(Ca)2.1-2.3; SK) channels, including the antimalarial plant alkaloid quinine, CyPPA, dequalinium, NS8593, SKA31 and UCL 1684. The most potent compound NS8593 (IC₅₀ 1.6 µM) specifically targeted TRPM7 as compared with other TRP channels, interfered with Mg²⁺ -dependent regulation of TRPM7 channel and inhibited the motility of cultured cells. NS8593 exhibited full and reversible block of native TRPM7-like currents in HEK 293 cells, freshly isolated smooth muscle cells, primary podocytes and ventricular myocytes. CONCLUSIONS AND IMPLICATIONS This study reveals a tight overlap in the pharmacological profiles of TRPM7 and K(Ca)2.1-2.3 channels. NS8593 acts as a negative gating modulator of TRPM7 and is well-suited to study functional features and cellular roles of endogenous TRPM7.
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Affiliation(s)
- V Chubanov
- Walther-Straub-Institute of Pharmacology and Toxicology, University of Munich, Munich, Germany.
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227
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Frühwald J, Camacho Londoño J, Dembla S, Mannebach S, Lis A, Drews A, Wissenbach U, Oberwinkler J, Philipp SE. Alternative splicing of a protein domain indispensable for function of transient receptor potential melastatin 3 (TRPM3) ion channels. J Biol Chem 2012; 287:36663-72. [PMID: 22961981 DOI: 10.1074/jbc.m112.396663] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
TRPM3 channels form ionotropic steroid receptors in the plasma membrane of pancreatic β and dorsal root ganglion cells and link steroid hormone signaling to insulin release and pain perception, respectively. We identified and compared the function of a number of TRPM3 splice variants present in mouse, rat and human tissues. We found that variants lacking a region of 18 amino acid residues display neither Ca(2+) entry nor ionic currents when expressed alone. Hence, splicing removes a region that is indispensable for channel function, which is called the ICF region. TRPM3 variants devoid of this region (TRPM3ΔICF), are ubiquitously present in different tissues and cell types where their transcripts constitute up to 15% of the TRPM3 isoforms. The ICF region is conserved throughout the TRPM family, and its presence in TRPM8 proteins is also necessary for function. Within the ICF region, 10 amino acid residues form a domain essential for the formation of operative TRPM3 channels. TRPM3ΔICF variants showed reduced interaction with other TRPM3 isoforms, and their occurrence at the cell membrane was diminished. Correspondingly, coexpression of ΔICF proteins with functional TRPM3 subunits not only reduced the number of channels but also impaired TRPM3-mediated Ca(2+) entry. We conclude that TRPM3ΔICF variants are regulatory channel subunits fine-tuning TRPM3 channel activity.
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Affiliation(s)
- Julia Frühwald
- From the Experimentelle und Klinische Pharmakologie und Toxikologie, Universität des Saarlandes, 66421 Homburg, Germany
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228
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Celsi F, D'Errico A, Menini A. Responses to sulfated steroids of female mouse vomeronasal sensory neurons. Chem Senses 2012; 37:849-58. [PMID: 22923146 DOI: 10.1093/chemse/bjs068] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The rodent vomeronasal organ plays an important role in many social behaviors. Using the calcium imaging technique with the dye fluo-4 we measured intracellular calcium concentration changes induced by the application of sulfated steroids to neurons isolated from the vomeronasal organ of female mice. We found that a mix of 10 sulfated steroids from the androgen, estrogen, pregnanolone, and glucocorticoid families induced a calcium response in 71% of neurons. Moreover, 31% of the neurons responded to a mix composed of 3 glucocorticoid-derived compounds, and 28% responded to a mix composed of 3 pregnanolone-derived compounds. Immunohistochemistry showed that neurons responding to sulfated steroids expressed phosphodiesterase 4A, a marker specific for apical neurons expressing V1R receptors. None of the neuron that responded to 1 mix responded also to the other, indicating a specificity of the responses. Some neurons responded to more than 1 individual component of the glucocorticoid-derived mix tested at high concentration, suggesting that these neurons are broadly tuned, although they still displayed strong specificity, remaining unresponsive to high concentrations of the ineffective compounds.
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Affiliation(s)
- Fulvio Celsi
- Neurobiology Sector, Scuola Internazionale Superiore di Studi Avanzati (SISSA), and Italian Institute of Technology, SISSA Unit, Trieste, Italy
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229
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Premkumar LS, Abooj M. TRP channels and analgesia. Life Sci 2012; 92:415-24. [PMID: 22910182 DOI: 10.1016/j.lfs.2012.08.010] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2012] [Revised: 07/25/2012] [Accepted: 08/02/2012] [Indexed: 01/07/2023]
Abstract
Since cloning and characterizing the first nociceptive ion channel Transient Receptor Potential (TRP) Vanilloid 1 (TRPV1), other TRP channels involved in nociception have been cloned and characterized, which include TRP Vanilloid 2 (TRPV2), TRP Vanilloid 3 (TRPV3), TRP Vanilloid 4 (TRPV4), TRP Ankyrin 1 (TRPA1) and TRP Melastatin 8 (TRPM8), more recently TRP Canonical 1, 5, 6 (TRPC1, 5, 6), TRP Melastatin 2 (TRPM2) and TRP Melastatin 3 (TRPM3). These channels are predominantly expressed in C and Aδ nociceptors and transmit noxious thermal, mechanical and chemical sensitivities. TRP channels are modulated by pro-inflammatory mediators, neuropeptides and cytokines. Significant advances have been made targeting these receptors either by antagonists or agonists to treat painful conditions. In this review, we will discuss TRP channels as targets for next generation analgesics and the side effects that may ensue as a result of blocking/activating these receptors, because they are also involved in physiological functions such as release of vasoactive neuropeptides and regulation of vascular tone, maintenance of the body temperature, gastrointestinal motility, urinary bladder control, etc.
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Affiliation(s)
- Louis S Premkumar
- Department of Pharmacology, Southern Illinois University School of Medicine Springfield, IL 62702, USA.
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Freichel M, Almering J, Tsvilovskyy V. The Role of TRP Proteins in Mast Cells. Front Immunol 2012; 3:150. [PMID: 22701456 PMCID: PMC3372879 DOI: 10.3389/fimmu.2012.00150] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Accepted: 05/22/2012] [Indexed: 01/16/2023] Open
Abstract
Transient receptor potential (TRP) proteins form cation channels that are regulated through strikingly diverse mechanisms including multiple cell surface receptors, changes in temperature, in pH and osmolarity, in cytosolic free Ca(2+) concentration ([Ca(2+)](i)), and by phosphoinositides which makes them polymodal sensors for fine tuning of many cellular and systemic processes in the body. The 28 TRP proteins identified in mammals are classified into six subfamilies: TRPC, TRPV, TRPM, TRPA, TRPML, and TRPP. When activated, they contribute to cell depolarization and Ca(2+) entry. In mast cells, the increase of [Ca(2+)](i) is fundamental for their biological activity, and several entry pathways for Ca(2+) and other cations were described including Ca(2+) release activated Ca(2+) (CRAC) channels. Like in other non-excitable cells, TRP channels could directly contribute to Ca(2+) influx via the plasma membrane as constituents of Ca(2+) conducting channel complexes or indirectly by shifting the membrane potential and regulation of the driving force for Ca(2+) entry through independent Ca(2+) entry channels. Here, we summarize the current knowledge about the expression of individual Trp genes with the majority of the 28 members being yet identified in different mast cell models, and we highlight mechanisms how they can regulate mast cell functions. Since specific agonists or blockers are still lacking for most members of the TRP family, studies to unravel their function and activation mode still rely on experiments using genetic approaches and transgenic animals. RNAi approaches suggest a functional role for TRPC1, TRPC5, and TRPM7 in mast cell derived cell lines or primary mast cells, and studies using Trp gene knock-out mice reveal a critical role for TRPM4 in mast cell activation and for mast cell mediated cutaneous anaphylaxis, whereas a direct role of cold- and menthol-activated TRPM8 channels seems to be unlikely for the development of cold urticaria at least in mice.
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Affiliation(s)
- Marc Freichel
- Pharmakologisches Institut, Universität HeidelbergHeidelberg, Germany
| | - Julia Almering
- Pharmakologisches Institut, Universität HeidelbergHeidelberg, Germany
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231
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Düfer M, Hörth K, Wagner R, Schittenhelm B, Prowald S, Wagner TFJ, Oberwinkler J, Lukowski R, Gonzalez FJ, Krippeit-Drews P, Drews G. Bile acids acutely stimulate insulin secretion of mouse β-cells via farnesoid X receptor activation and K(ATP) channel inhibition. Diabetes 2012; 61:1479-89. [PMID: 22492528 PMCID: PMC3357280 DOI: 10.2337/db11-0815] [Citation(s) in RCA: 122] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Type 2 diabetes mellitus is associated with alterations in bile acid (BA) signaling. The aim of our study was to test whether pancreatic β-cells contribute to BA-dependent regulation of glucose homeostasis. Experiments were performed with islets from wild-type, farnesoid X receptor (FXR) knockout (KO), and β-cell ATP-dependent K(+) (K(ATP)) channel gene SUR1 (ABCC8) KO mice, respectively. Sodium taurochenodeoxycholate (TCDC) increased glucose-induced insulin secretion. This effect was mimicked by the FXR agonist GW4064 and suppressed by the FXR antagonist guggulsterone. TCDC and GW4064 stimulated the electrical activity of β-cells and enhanced cytosolic Ca(2+) concentration ([Ca(2+)](c)). These effects were blunted by guggulsterone. Sodium ursodeoxycholate, which has a much lower affinity to FXR than TCDC, had no effect on [Ca(2+)](c) and insulin secretion. FXR activation by TCDC is suggested to inhibit K(ATP) current. The decline in K(ATP) channel activity by TCDC was only observed in β-cells with intact metabolism and was reversed by guggulsterone. TCDC did not alter insulin secretion in islets of SUR1-KO or FXR-KO mice. TCDC did not change islet cell apoptosis. This is the first study showing an acute action of BA on β-cell function. The effect is mediated by FXR by nongenomic elements, suggesting a novel link between FXR activation and K(ATP) channel inhibition.
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Affiliation(s)
- Martina Düfer
- Department of Pharmacology, Institute of Pharmacy, University of Tübingen, Tübingen, Germany.
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232
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Cao DS, Zhong L, Hsieh TH, Abooj M, Bishnoi M, Hughes L, Premkumar LS. Expression of transient receptor potential ankyrin 1 (TRPA1) and its role in insulin release from rat pancreatic beta cells. PLoS One 2012; 7:e38005. [PMID: 22701540 PMCID: PMC3365106 DOI: 10.1371/journal.pone.0038005] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2011] [Accepted: 05/01/2012] [Indexed: 11/19/2022] Open
Abstract
Objective Several transient receptor potential (TRP) channels are expressed in pancreatic beta cells and have been proposed to be involved in insulin secretion. However, the endogenous ligands for these channels are far from clear. Here, we demonstrate the expression of the transient receptor potential ankyrin 1 (TRPA1) ion channel in the pancreatic beta cells and its role in insulin release. TRPA1 is an attractive candidate for inducing insulin release because it is calcium permeable and is activated by molecules that are produced during oxidative glycolysis. Methods Immunohistochemistry, RT-PCR, and Western blot techniques were used to determine the expression of TRPA1 channel. Ca2+ fluorescence imaging and electrophysiology (voltage- and current-clamp) techniques were used to study the channel properties. TRPA1-mediated insulin release was determined using ELISA. Results TRPA1 is abundantly expressed in a rat pancreatic beta cell line and freshly isolated rat pancreatic beta cells, but not in pancreatic alpha cells. Activation of TRPA1 by allyl isothiocyanate (AITC), hydrogen peroxide (H2O2), 4-hydroxynonenal (4-HNE), and cyclopentenone prostaglandins (PGJ2) and a novel agonist methylglyoxal (MG) induces membrane current, depolarization, and Ca2+ influx leading to generation of action potentials in a pancreatic beta cell line and primary cultured pancreatic beta cells. Activation of TRPA1 by agonists stimulates insulin release in pancreatic beta cells that can be inhibited by TRPA1 antagonists such as HC030031 or AP-18 and by RNA interference. TRPA1-mediated insulin release is also observed in conditions of voltage-gated Na+ and Ca2+ channel blockade as well as ATP sensitive potassium (KATP) channel activation. Conclusions We propose that endogenous and exogenous ligands of TRPA1 cause Ca2+ influx and induce basal insulin release and that TRPA1-mediated depolarization acts synergistically with KATP channel blockade to facilitate insulin release.
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Affiliation(s)
- De-Shou Cao
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, Illinois, United States of America
- * E-mail: (DSC); (LSP)
| | - Linlin Zhong
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, Illinois, United States of America
| | - Tsung-han Hsieh
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, Illinois, United States of America
| | - Mruvil Abooj
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, Illinois, United States of America
| | - Mahendra Bishnoi
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, Illinois, United States of America
| | - Lauren Hughes
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, Illinois, United States of America
| | - Louis S. Premkumar
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, Illinois, United States of America
- * E-mail: (DSC); (LSP)
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233
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Kusudo T, Wang Z, Mizuno A, Suzuki M, Yamashita H. TRPV4 deficiency increases skeletal muscle metabolic capacity and resistance against diet-induced obesity. J Appl Physiol (1985) 2012; 112:1223-32. [DOI: 10.1152/japplphysiol.01070.2011] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Transient receptor potential channel V4 (TRPV4) functions as a nonselective cation channel in various cells and plays physiological roles in osmotic and thermal sensation. However, the function of TRPV4 in energy metabolism is unknown. Here, we report that TRPV4 deficiency results in increased muscle oxidative capacity and resistance to diet-induced obesity in mice. Although no difference in body weight was observed between wild-type and Trpv4−/− mice when fed a standard chow diet, obesity phenotypes induced by a high-fat diet were significantly improved in Trpv4−/− mice, without any change in food intake. Quantitative analysis of mRNA revealed the constitutive upregulation of many genes, including those for transcription factors such as peroxisome proliferator-activated receptor α and for metabolic enzymes such as phosphoenolpyruvate carboxykinase. These upregulated genes were especially prominent in oxidative skeletal muscle, in which the activity of Ca2+-dependent phosphatase calcineurin was elevated, suggesting that other Ca2+ channels function in the skeletal muscle of Trpv4−/− mice. Indeed, gene expressions for TRPC3 and TRPC6 increased in the muscles of Trpv4−/− mice compared with those of wild-type mice. The number of oxidative type I fiber also increased in the mutant muscles following myogenin gene induction. These results strongly suggested that inactivation of Trpv4 induces compensatory increases in TRPC3 and TRPC6 production, and elevation of calcineurin activity, affecting energy metabolism through increased expression of genes involved in fuel oxidation in skeletal muscle and thereby contributing to increased energy expenditure and protection from diet-induced obesity in mice.
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Affiliation(s)
- Tatsuya Kusudo
- Department of Biomedical Sciences, College of Life and Health Sciences, Chubu University, Kasugai; and
| | - Zhonghua Wang
- Department of Biomedical Sciences, College of Life and Health Sciences, Chubu University, Kasugai; and
| | - Atsuko Mizuno
- Department of Pharmacology, Division of Molecular Pharmacology, Jichi Medical University, Shimotsuke, Japan
| | - Makoto Suzuki
- Department of Pharmacology, Division of Molecular Pharmacology, Jichi Medical University, Shimotsuke, Japan
| | - Hitoshi Yamashita
- Department of Biomedical Sciences, College of Life and Health Sciences, Chubu University, Kasugai; and
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234
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Finol-Urdaneta RK, Remedi MS, Raasch W, Becker S, Clark RB, Strüver N, Pavlov E, Nichols CG, French RJ, Terlau H. Block of Kv1.7 potassium currents increases glucose-stimulated insulin secretion. EMBO Mol Med 2012; 4:424-34. [PMID: 22438204 PMCID: PMC3403299 DOI: 10.1002/emmm.201200218] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Revised: 01/12/2012] [Accepted: 01/13/2012] [Indexed: 01/26/2023] Open
Abstract
Glucose-stimulated insulin secretion (GSIS) relies on repetitive, electrical spiking activity of the beta cell membrane. Cyclic activation of voltage-gated potassium channels (Kv) generates an outward, ‘delayed rectifier’ potassium current, which drives the repolarizing phase of each spike and modulates insulin release. Although several Kv channels are expressed in pancreatic islets, their individual contributions to GSIS remain incompletely understood. We take advantage of a naturally occurring cone-snail peptide toxin, Conkunitzin-S1 (Conk-S1), which selectively blocks Kv1.7 channels to provide an intrinsically limited, finely graded control of total beta cell delayed rectifier current and hence of GSIS. Conk-S1 increases GSIS in isolated rat islets, likely by reducing Kv1.7-mediated delayed rectifier currents in beta cells, which yields increases in action potential firing and cytoplasmic free calcium. In rats, Conk-S1 increases glucose-dependent insulin secretion without decreasing basal glucose. Thus, we conclude that Kv1.7 contributes to the membrane-repolarizing current of beta cells during GSIS and that block of this specific component of beta cell Kv current offers a potential strategy for enhancing GSIS with minimal risk of hypoglycaemia during metabolic disorders such as Type 2 diabetes.
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Affiliation(s)
- Rocio K Finol-Urdaneta
- Department of Physiology and Pharmacology, and HBI, University of Calgary, Calgary, AB, Canada
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235
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Abstract
Transient receptor potential canonical (TRPC) channels are the canonical (C) subset of the TRP proteins, which are widely expressed in mammalian cells. They are thought to be primarily involved in determining calcium and sodium entry and have wide-ranging functions that include regulation of cell proliferation, motility and contraction. The channels are modulated by a multiplicity of factors, putatively existing as integrators in the plasma membrane. This review considers the sensitivities of TRPC channels to lipids that include diacylglycerols, phosphatidylinositol bisphosphate, lysophospholipids, oxidized phospholipids, arachidonic acid and its metabolites, sphingosine-1-phosphate, cholesterol and some steroidal derivatives and other lipid factors such as gangliosides. Promiscuous and selective lipid sensing have been detected. There appear to be close working relationships with lipids of the phospholipase C and A2 enzyme systems, which may enable integration with receptor signalling and membrane stretch. There are differences in the properties of each TRPC channel that are further complicated by TRPC heteromultimerization. The lipids modulate activity of the channels or insertion in the plasma membrane. Lipid microenvironments and intermediate sensing proteins have been described that include caveolae, G protein signalling, SEC14-like and spectrin-type domains 1 (SESTD1) and podocin. The data suggest that lipid sensing is an important aspect of TRPC channel biology enabling integration with other signalling systems.
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Affiliation(s)
- D. J. Beech
- Faculty of Biological Sciences, Institute of Membrane and Systems Biology, University of Leeds, Leeds, UK
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236
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Fågelskiöld AJ, Kannisto K, Boström A, Hadrovic B, Farre C, Eweida M, Wester K, Islam MS. Insulin-secreting INS-1E cells express functional TRPV1 channels. Islets 2012; 4:56-63. [PMID: 22274646 DOI: 10.4161/isl.18915] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
We have studied whether functional TRPV1 channels exist in the INS-1E cells, a cell type used as a model for β-cells, and in primary β-cells from rat and human. The effects of the TRPV1 agonists capsaicin and AM404 on the intracellular free Ca (2+) concentration ([Ca (2+)]i) in the INS-1E cells were studied by fura-2 based microfluorometry. Capsaicin increased [Ca (2+)]i in a concentration-dependent manner, and the [Ca (2+)]i increase was dependent on extracellular Ca (2+). AM404 also increased [Ca (2+)]i in the INS-1E cells. Capsazepine, a specific antagonist of TRPV1, completely blocked the capsaicin- and AM404-induced [Ca (2+)]i increases. Capsaicin did not increase [Ca (2+)]i in the primary β-cells from rat and human. Whole cell patch clamp configuration was used to record currents across the plasma membrane in the INS-1E cells. Capsaicin elicited inward currents that were inhibited by capsazepine. Western blot analysis detected TRPV1 proteins in the INS-1E cells and the human islets. Immunohistochemistry was used to study the expression of TRPV1, but no TRPV1 protein immunoreactivity was detected in the human islet cells and the human insulinoma cells. We conclude that the INS-1E cells, but not the primary β-cells, express functional TRPV1 channels.
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Affiliation(s)
- Amanda Jabin Fågelskiöld
- Department of Clinical Science and Education; Södersjukhuset; Karolinska Institutet; Stockholm, Sweden
| | - Kristina Kannisto
- Department of Clinical Science and Education; Södersjukhuset; Karolinska Institutet; Stockholm, Sweden
| | - Anna Boström
- Department of Clinical Science and Education; Södersjukhuset; Karolinska Institutet; Stockholm, Sweden
| | - Banina Hadrovic
- Department of Clinical Science and Education; Södersjukhuset; Karolinska Institutet; Stockholm, Sweden
| | | | - Mohamed Eweida
- Department of Clinical Science and Education; Södersjukhuset; Karolinska Institutet; Stockholm, Sweden
| | - Kenneth Wester
- Department of Genetics and Pathology; the Rudbeck Laboratory; Uppsala University; Uppsala, Sweden
| | - Md Shahidul Islam
- Department of Clinical Science and Education; Södersjukhuset; Karolinska Institutet; Stockholm, Sweden; Internal Medicine; Uppsala University Hospital; Uppsala, Sweden
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237
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Numazawa S, Takase M, Ahiko T, Ishii M, Shimizu SI, Yoshida T. Possible Involvement of Transient Receptor Potential Channels in Electrophile-Induced Insulin Secretion from RINm5F Cells. Biol Pharm Bull 2012; 35:346-54. [DOI: 10.1248/bpb.35.346] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Satoshi Numazawa
- Department of Biochemical Toxicology, Showa University School of Pharmacy
| | - Makiko Takase
- Department of Biochemical Toxicology, Showa University School of Pharmacy
| | - Tomomi Ahiko
- Department of Biochemical Toxicology, Showa University School of Pharmacy
| | - Masakazu Ishii
- Department of Pathophysiology, Showa University School of Pharmacy
| | | | - Takemi Yoshida
- Department of Biochemical Toxicology, Showa University School of Pharmacy
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238
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Pregnenolone sulphate-independent inhibition of TRPM3 channels by progesterone. Cell Calcium 2011; 51:1-11. [PMID: 22000496 PMCID: PMC3275754 DOI: 10.1016/j.ceca.2011.09.005] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2011] [Revised: 09/12/2011] [Accepted: 09/21/2011] [Indexed: 11/23/2022]
Abstract
Transient Receptor Potential Melastatin 3 (TRPM3) is a widely expressed calcium-permeable non-selective cation channel that is stimulated by high concentrations of nifedipine or by physiological steroids that include pregnenolone sulphate. Here we sought to identify steroids that inhibit TRPM3. Channel activity was studied using calcium-measurement and patch-clamp techniques. Progesterone (0.01–10 μM) suppressed TRPM3 activity evoked by pregnenolone sulphate. Progesterone metabolites and 17β-oestradiol were also inhibitory but the effects were relatively small. Dihydrotestosterone was an inhibitor at concentrations higher than 1 μM. Corticosteroids lacked effect. Overlay assays indicated that pregnenolone sulphate, progesterone and dihydrotestosterone bound to TRPM3. In contrast to dihydrotestosterone, progesterone inhibited nifedipine-evoked TRPM3 activity or activity in the absence of an exogenous activator, suggesting a pregnenolone sulphate-independent mechanism of action. Dihydrotestosterone, like a non-steroid look-alike compound, acted as a competitive antagonist at the pregnenolone sulphate binding site. Progesterone inhibited endogenous TRPM3 in vascular smooth muscle cells. Relevance of TRPM3 or the progesterone effect to ovarian cells, which have been suggested to express TRPM3, was not identified. The data further define a chemical framework for competition with pregnenolone sulphate at TRPM3 and expand knowledge of steroid interactions with TRPM3, suggesting direct steroid binding and pregnenolone sulphate-independent inhibition by progesterone.
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239
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Zamudio-Bulcock PA, Everett J, Harteneck C, Valenzuela CF. Activation of steroid-sensitive TRPM3 channels potentiates glutamatergic transmission at cerebellar Purkinje neurons from developing rats. J Neurochem 2011; 119:474-85. [PMID: 21955047 DOI: 10.1111/j.1471-4159.2011.07441.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The functional implications of transient receptor potential melastatin 3 (TRPM3) activation, the most recently described member of the melastatin subfamily of cation permeable TRP channels, have begun to be elucidated in recent years. The discovery of TRPM3 activation by the steroid pregnenolone sulfate (PregS) has shed new light on the physiological role of this channel. For example, TRPM3 activation enhances insulin secretion from β pancreatic cells, induces contraction of vascular smooth muscle, and is also involved in the detection of noxious heat. Although TRPM3 expression has been detected in several regions of the developing and mature brain, little is known about the roles of TRPM3 in brain physiology. In this study, we demonstrate the abundant expression of TRPM3 steroid-sensitive channels in the developing cerebellar cortex. We also show that TRPM3-like channels are expressed at glutamatergic synapses in neonatal Purkinje cells. We recently showed that PregS potentiates spontaneous glutamate release onto neonatal Purkinje cells during a period of active glutamatergic synapse formation; we now show that this effect of PregS is mediated by TRPM3-like channels. Mefenamic acid, a recently discovered TRPM3 antagonist, blocked the effect of PregS on glutamate release. The PregS effect on glutamate release was mimicked by other TRPM3 agonists (nifedipine and epipregnanolone sulfate) but not by a TRMP3-inactive steroid (progesterone). Our findings identify TRPM3 channels as novel modulators of glutamatergic transmission in the developing brain.
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Affiliation(s)
- Paula A Zamudio-Bulcock
- Department of Neurosciences, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87131-0001, USA
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240
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Müller I, Rössler OG, Thiel G. Pregnenolone sulfate activates basic region leucine zipper transcription factors in insulinoma cells: role of voltage-gated Ca2+ channels and transient receptor potential melastatin 3 channels. Mol Pharmacol 2011; 80:1179-89. [PMID: 21948387 DOI: 10.1124/mol.111.074781] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The neurosteroid pregnenolone sulfate activates a signaling cascade in insulinoma cells involving activation of extracellular signal-regulated protein kinase and enhanced expression of the transcription factor Egr-1. Here, we show that pregnenolone sulfate stimulation leads to a significant elevation of activator protein-1 (AP-1) activity in insulinoma cells. Expression of the basic region leucine zipper (bZIP) transcription factors c-Jun and c-Fos is up-regulated in insulinoma cells and pancreatic β-cells in primary culture after pregnenolone sulfate stimulation. Up-regulation of a chromatin-embedded c-Jun promoter/luciferase reporter gene transcription in pregnenolone sulfate-stimulated insulinoma cells was impaired when the AP-1 binding sites were mutated, indicating that these motifs function as pregnenolone sulfate response elements. In addition, phosphorylation of cAMP response element (CRE)-binding protein is induced and transcription of a CRE-controlled reporter gene is stimulated after pregnenolone sulfate treatment, indicating that the CRE functions as a pregnenolone sulfate response element as well. Pharmacological and genetic experiments revealed that both L-type Ca(2+) channels and transient receptor potential melastatin 3 (TRPM3) channels are essential for connecting pregnenolone sulfate stimulation with enhanced AP-1 activity and bZIP-mediated transcription in insulinoma cells. In contrast, pregnenolone sulfate stimulation did not enhance AP-1 activity or c-Jun and c-Fos expression in pituitary corticotrophs that express functional L-type Ca(2+) channels but only trace amounts of TRPM3. We conclude that expression of L-type Ca(2+) channels is not sufficient to activate bZIP-mediated gene transcription by pregnenolone sulfate. Rather, additional expression of TRPM3 or depolarization of the cells is required to connect pregnenolone sulfate stimulation with enhanced gene transcription.
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Affiliation(s)
- Isabelle Müller
- Department of Medical Biochemistry and Molecular Biology, University of Saarland Medical Center, Homburg, Germany
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241
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Klose C, Straub I, Riehle M, Ranta F, Krautwurst D, Ullrich S, Meyerhof W, Harteneck C. Fenamates as TRP channel blockers: mefenamic acid selectively blocks TRPM3. Br J Pharmacol 2011; 162:1757-69. [PMID: 21198543 DOI: 10.1111/j.1476-5381.2010.01186.x] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND AND PURPOSE Fenamates are N-phenyl-substituted anthranilic acid derivatives clinically used as non-steroid anti-inflammatory drugs in pain treatment. Reports describing fenamates as tools to interfere with cellular volume regulation attracted our attention based on our interest in the role of the volume-modulated transient receptor potential (TRP) channels TRPM3 and TRPV4. EXPERIMENTAL APPROACH Firstly, we measured the blocking potencies and selectivities of fenamates on TRPM3 and TRPV4 as well as TRPC6 and TRPM2 by Ca(2+) imaging in the heterologous HEK293 cell system. Secondly, we further investigated the effects of mefenamic acid on cytosolic Ca(2+) and on the membrane voltage in single HEK293 cells that exogenously express TRPM3. Thirdly, in insulin-secreting INS-1E cells, which endogenously express TRPM3, we validated the effect of mefenamic acid on cytosolic Ca(2+) and insulin secretion. KEY RESULTS We identified and characterized mefenamic acid as a selective and potent TRPM3 blocker, whereas other fenamate structures non-selectively blocked TRPM3, TRPV4, TRPC6 and TRPM2. CONCLUSIONS AND IMPLICATIONS This study reveals that mefenamic acid selectively inhibits TRPM3-mediated calcium entry. This selectivity was further confirmed using insulin-secreting cells. K(ATP) channel-dependent increases in cytosolic Ca(2+) and insulin secretion were not blocked by mefenamic acid, but the selective stimulation of TRPM3-dependent Ca(2+) entry and insulin secretion induced by pregnenolone sulphate were inhibited. However, the physiological regulator of TRPM3 in insulin-secreting cells remains to be elucidated, as well as the conditions under which the inhibition of TRPM3 can impair pancreatic β-cell function. Our results strongly suggest mefenamic acid is the most selective fenamate to interfere with TRPM3 function.
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Affiliation(s)
- Chihab Klose
- Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Interfaculty Center of Pharmacogenomics and Pharmaceutical Research (ICePhA), Eberhard-Karls-University, Tübingen, Germany
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242
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Majeed Y, Amer MS, Agarwal AK, McKeown L, Porter KE, O'Regan DJ, Naylor J, Fishwick CWG, Muraki K, Beech DJ. Stereo-selective inhibition of transient receptor potential TRPC5 cation channels by neuroactive steroids. Br J Pharmacol 2011; 162:1509-20. [PMID: 21108630 PMCID: PMC3057289 DOI: 10.1111/j.1476-5381.2010.01136.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND AND PURPOSE Transient receptor potential canonical 5 (TRPC5) channels are widely expressed, including in the CNS, where they potentiate fear responses. They also contribute to other non-selective cation channels that are stimulated by G-protein-coupled receptor agonists and lipid and redox factors. Steroids are known to modulate fear and anxiety states, and we therefore investigated whether TRPC5 exhibited sensitivity to steroids. EXPERIMENTAL APPROACH Human TRPC5 channels were conditionally expressed in HEK293 cells and studied using intracellular Ca2+ measurement, whole-cell voltage-clamp and excised patch techniques. For comparison, control experiments were performed with cells lacking TRPC5 channels or expressing another TRP channel, TRPM2. Native TRPC channel activity was recorded from vascular smooth muscle cells. KEY RESULTS Extracellular application of pregnenolone sulphate, pregnanolone sulphate, pregnanolone, progesterone or dihydrotestosterone inhibited TRPC5 activity within 1–2 min. Dehydroepiandrosterone sulphate or 17β-oestradiol had weak inhibitory effects. Pregnenolone, and allopregnanolone, a progesterone metabolite and stereo-isomer of pregnanolone, all had no effects. Progesterone was the most potent of the steroids, especially against TRPC5 channel activity evoked by sphingosine-1-phosphate. In outside-out patch recordings, bath-applied progesterone and dihydrotestosterone had strong and reversible effects, suggesting relatively direct mechanisms of action. Progesterone inhibited native TRPC5-containing channel activity, evoked by oxidized phospholipid. CONCLUSIONS AND IMPLICATIONS Our data suggest that TRPC5 channels are susceptible to relatively direct and rapid stereo-selective steroid modulation, leading to channel inhibition. The study adds to growing appreciation of TRP channels as non-genomic steroid sensors.
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Affiliation(s)
- Y Majeed
- Multidisciplinary Cardiovascular Research Centre, University of Leeds, Leeds, UK
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243
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Vriens J, Owsianik G, Hofmann T, Philipp SE, Stab J, Chen X, Benoit M, Xue F, Janssens A, Kerselaers S, Oberwinkler J, Vennekens R, Gudermann T, Nilius B, Voets T. TRPM3 is a nociceptor channel involved in the detection of noxious heat. Neuron 2011; 70:482-94. [PMID: 21555074 DOI: 10.1016/j.neuron.2011.02.051] [Citation(s) in RCA: 383] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/18/2011] [Indexed: 10/18/2022]
Abstract
Transient receptor potential melastatin-3 (TRPM3) is a broadly expressed Ca(2+)-permeable nonselective cation channel. Previous work has demonstrated robust activation of TRPM3 by the neuroactive steroid pregnenolone sulfate (PS), but its in vivo gating mechanisms and functions remained poorly understood. Here, we provide evidence that TRPM3 functions as a chemo- and thermosensor in the somatosensory system. TRPM3 is molecularly and functionally expressed in a large subset of small-diameter sensory neurons from dorsal root and trigeminal ganglia, and mediates the aversive and nocifensive behavioral responses to PS. Moreover, we demonstrate that TRPM3 is steeply activated by heating and underlies heat sensitivity in a subset of sensory neurons. TRPM3-deficient mice exhibited clear deficits in their avoidance responses to noxious heat and in the development of inflammatory heat hyperalgesia. These experiments reveal an unanticipated role for TRPM3 as a thermosensitive nociceptor channel implicated in the detection of noxious heat.
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Affiliation(s)
- Joris Vriens
- Laboratory of Ion Channel Research and TRP Research Platform Leuven (TRPLe), KU Leuven, 3000 Leuven, Belgium.
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244
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Kukkonen JP. A ménage à trois made in heaven: G-protein-coupled receptors, lipids and TRP channels. Cell Calcium 2011; 50:9-26. [DOI: 10.1016/j.ceca.2011.04.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Revised: 04/21/2011] [Accepted: 04/22/2011] [Indexed: 12/15/2022]
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245
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Goswami C, Kuhn J, Dina OA, Fernández-Ballester G, Levine JD, Ferrer-Montiel A, Hucho T. Estrogen destabilizes microtubules through an ion-conductivity-independent TRPV1 pathway. J Neurochem 2011; 117:995-1008. [PMID: 21480900 DOI: 10.1111/j.1471-4159.2011.07270.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Recently, we described estrogen and agonists of the G-protein coupled estrogen receptor GPR30 to induce protein kinase C (PKC)ε-dependent pain sensitization. PKCε phosphorylates the ion channel transient receptor potential, vanilloid subclass I (TRPV1) close to a novel microtubule-TRPV1 binding site. We now modeled the binding of tubulin to the TRPV1 C-terminus. The model suggests PKCε phosphorylation of TRPV1-S800 to abolish the tubulin-TRPV1 interaction. Indeed, in vitro PKCε phosphorylation of TRPV1 hindered tubulin-binding to TRPV1. In vivo, treatment of sensory neurons and F-11 cells with estrogen and the GPR30 agonist, G-1, resulted in microtubule destabilization and retraction of microtubules from filopodial structures. We found estrogen and G-1 to regulate the stability of the microtubular network via PKC phosphorylation of the PKCε-phosphorylation site TRPV1-S800. Microtubule disassembly was not, however, dependent on TRPV1 ion conductivity. TRPV1 knock-down in rats inverted the effect of the microtubule-modulating drugs, Taxol and Nocodazole, on estrogen-induced and PKCε-dependent mechanical pain sensitization. Thus, we suggest the C-terminus of TRPV1 to be a signaling intermediate downstream of estrogen and PKCε, regulating microtubule-stability and microtubule-dependent pain sensitization.
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Affiliation(s)
- Chandan Goswami
- Department for Molecular Human Genetics, Max Planck Institute for Molecular Genetics, Berlin, Germany
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246
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Nelson PL, Zolochevska O, Figueiredo ML, Soliman A, Hsu WH, Feng JM, Zhang H, Cheng H. Regulation of Ca(2+)-entry in pancreatic α-cell line by transient receptor potential melastatin 4 plays a vital role in glucagon release. Mol Cell Endocrinol 2011; 335:126-34. [PMID: 21238535 DOI: 10.1016/j.mce.2011.01.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2010] [Revised: 01/04/2011] [Accepted: 01/06/2011] [Indexed: 10/18/2022]
Abstract
Elevation in the intracellular Ca(2+) concentration stimulates glucagon secretion from pancreatic α-cells. The Transient Receptor Potential Melastatin 4 channel (TRPM4) is critical for Ca(2+) signaling. However, its role in glucagon secreting α-cells has not been investigated. We identified TRPM4 gene expression and protein in the αTC1-6 cell line using RT-PCR and immunocytochemistry. Furthermore, we performed a detailed biophysical characterization of the channel using the patch-clamp technique to confirm that currents typical for TRPM4 were present in αTC1-6 cells. To investigate TRPM4 function, we generated a stable knockdown clone using shRNA and a lentiviral vector. Inhibition of TRPM4 significantly reduced the responses to different agonists during Ca(2+) imaging analysis with Fura-2AM. The reduction in the magnitude of Ca(2+) signals resulted in decreased glucagon secretion. These results suggested that depolarization by TRPM4 may play an important role in controlling glucagon secretion from α-cells and perhaps glucose homeostasis.
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Affiliation(s)
- P L Nelson
- Department of Comparative Biomedical Sciences, School of Veterinary Medicine, Louisiana State University, Skip Bertman Drive, Baton Rouge, LA 70803, USA
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247
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Majeed Y, Bahnasi Y, Seymour VAL, Wilson LA, Milligan CJ, Agarwal AK, Sukumar P, Naylor J, Beech DJ. Rapid and contrasting effects of rosiglitazone on transient receptor potential TRPM3 and TRPC5 channels. Mol Pharmacol 2011; 79:1023-30. [PMID: 21406603 DOI: 10.1124/mol.110.069922] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The aim of this study was to generate new insight into chemical regulation of transient receptor potential (TRP) channels with relevance to glucose homeostasis and the metabolic syndrome. Human TRP melastatin 2 (TRPM2), TRPM3, and TRP canonical 5 (TRPC5) were conditionally overexpressed in human embryonic kidney 293 cells and studied by using calcium-measurement and patch-clamp techniques. Rosiglitazone and other peroxisome proliferator-activated receptor-γ (PPAR-γ) agonists were investigated. TRPM2 was unaffected by rosiglitazone at concentrations up to 10 μM but was inhibited completely at higher concentrations (IC(50), ∼22.5 μM). TRPM3 was more potently inhibited, with effects occurring in a biphasic concentration-dependent manner such that there was approximately 20% inhibition at low concentrations (0.1-1 μM) and full inhibition at higher concentrations (IC(50), 5-10 μM). PPAR-γ antagonism by 2-chloro-5-nitrobenzanilide (GW9662) did not prevent inhibition of TRPM3 by rosiglitazone. TRPC5 was strongly stimulated by rosiglitazone at concentrations of ≥10 μM (EC(50), ∼30 μM). Effects on TRPM3 and TRPC5 occurred rapidly and reversibly. Troglitazone and pioglitazone inhibited TRPM3 (IC(50), 12 μM) but lacked effect on TRPC5, suggesting no relevance of PPAR-γ or the thiazolidinedione moiety to rosiglitazone stimulation of TRPC5. A rosiglitazone-related but nonthiazolidinedione PPAR-γ agonist, N-(2-benzoylphenyl)-O-[2-(methyl-2-pyridinylamino)ethyl]-l-tyrosine (GW1929), was a weak stimulator of TRPM3 and TRPC5. The natural PPAR-γ agonist 15-deoxy prostaglandin J(2), had no effect on TRPM3 or TRPC5. The data suggest that rosiglitazone contains chemical moieties that rapidly, strongly, and differentially modulate TRP channels independently of PPAR-γ, potentially contributing to biological consequences of the agent and providing the basis for novel TRP channel pharmacology.
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Affiliation(s)
- Yasser Majeed
- Multidisciplinary Cardiovascular Research Centre and Institute of Membrane and Systems Biology, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
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Morgans CW, Brown RL, Duvoisin RM. TRPM1: the endpoint of the mGluR6 signal transduction cascade in retinal ON-bipolar cells. Bioessays 2011; 32:609-14. [PMID: 20544736 DOI: 10.1002/bies.200900198] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
For almost 30 years the ion channel that initiates the ON visual pathway in vertebrate vision has remained elusive. Recent findings now indicate that the pathway, which begins with unbinding of glutamate from the metabotropic glutamate receptor 6 (mGluR6), ends with the opening of the transient receptor potential (TRP)M1 cation channel. As a component of the mGluR6 signal transduction pathway, mutations in TRPM1 would be expected to cause congenital stationary night blindness (CSNB), and several such mutations have already been identified in CSNB families. Furthermore, expression of TRPM1 in both the retina and skin raises the possibility that a genetic link exists between certain types of visual and skin disorders.
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Transient receptor proteins illuminated: Current views on TRPs and disease. Vet J 2011; 187:153-64. [DOI: 10.1016/j.tvjl.2010.01.020] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2009] [Revised: 01/21/2010] [Accepted: 01/25/2010] [Indexed: 11/23/2022]
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Lambert S, Drews A, Rizun O, Wagner TFJ, Lis A, Mannebach S, Plant S, Portz M, Meissner M, Philipp SE, Oberwinkler J. Transient receptor potential melastatin 1 (TRPM1) is an ion-conducting plasma membrane channel inhibited by zinc ions. J Biol Chem 2011; 286:12221-33. [PMID: 21278253 DOI: 10.1074/jbc.m110.202945] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
TRPM1 is the founding member of the melastatin subgroup of transient receptor potential (TRP) proteins, but it has not yet been firmly established that TRPM1 proteins form ion channels. Consequently, the biophysical and pharmacological properties of these proteins are largely unknown. Here we show that heterologous expression of TRPM1 proteins induces ionic conductances that can be activated by extracellular steroid application. However the current amplitudes observed were too small to enable a reliable biophysical characterization. We overcame this limitation by modifying TRPM1 channels in several independent ways that increased the similarity to the closely related TRPM3 channels. The resulting constructs produced considerably larger currents after overexpression. We also demonstrate that unmodified TRPM1 and TRPM3 proteins form functional heteromultimeric channels. With these approaches, we measured the divalent permeability profile and found that channels containing the pore of TRPM1 are inhibited by extracellular zinc ions at physiological concentrations, in contrast to channels containing only the pore of TRPM3. Applying these findings to pancreatic β cells, we found that TRPM1 proteins do not play a major role in steroid-activated currents of these cells. The inhibition of TRPM1 by zinc ions is primarily due to a short stretch of seven amino acids present only in the pore region of TRPM1 but not of TRPM3. Combined, our data demonstrate that TRPM1 proteins are bona fide ion-conducting plasma membrane channels. Their distinct biophysical properties allow a reliable identification of endogenous TRPM1-mediated currents.
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Affiliation(s)
- Sachar Lambert
- Experimentelle und Klinische Pharmakologie und Toxikologie, Universität des Saarlandes, 66421 Homburg, Germany
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