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Gardner EC, Tramont C, Bachanová P, Wang C, Do H, Boutz DR, Kar S, Zemelman BV, Gollihar JD, Ellington AD. Engineering a human P2X2 receptor with altered ligand selectivity in yeast. J Biol Chem 2024; 300:107248. [PMID: 38556082 PMCID: PMC11063903 DOI: 10.1016/j.jbc.2024.107248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Revised: 03/14/2024] [Accepted: 03/23/2024] [Indexed: 04/02/2024] Open
Abstract
P2X receptors are a family of ligand gated ion channels found in a range of eukaryotic species including humans but are not naturally present in the yeast Saccharomyces cerevisiae. We demonstrate the first recombinant expression and functional gating of the P2X2 receptor in baker's yeast. We leverage the yeast host for facile genetic screens of mutant P2X2 by performing site saturation mutagenesis at residues of interest, including SNPs implicated in deafness and at residues involved in native binding. Deep mutational analysis and rounds of genetic engineering yield mutant P2X2 F303Y A304W, which has altered ligand selectivity toward the ATP analog AMP-PNP. The F303Y A304W variant shows over 100-fold increased intracellular calcium amplitudes with AMP-PNP compared to the WT receptor and has a much lower desensitization rate. Since AMP-PNP does not naturally activate P2X receptors, the F303Y A304W P2X2 may be a starting point for downstream applications in chemogenetic cellular control. Interestingly, the A304W mutation selectively destabilizes the desensitized state, which may provide a mechanistic basis for receptor opening with suboptimal agonists. The yeast system represents an inexpensive, scalable platform for ion channel characterization and engineering by circumventing the more expensive and time-consuming methodologies involving mammalian hosts.
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Affiliation(s)
- Elizabeth C Gardner
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, Texas, USA
| | - Caitlin Tramont
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, Texas, USA
| | - Petra Bachanová
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, Texas, USA
| | - Chad Wang
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, Texas, USA
| | - Hannah Do
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, Texas, USA
| | - Daniel R Boutz
- Antibody Discovery and Accelerated Protein Therapeutics, Department of Pathology & Genomic Medicine, Houston Methodist Research Institute, Houston, Texas, USA
| | - Shaunak Kar
- Antibody Discovery and Accelerated Protein Therapeutics, Department of Pathology & Genomic Medicine, Houston Methodist Research Institute, Houston, Texas, USA
| | - Boris V Zemelman
- Department of Neuroscience, Center for Learning and Memory, The University of Texas at Austin, Austin, Texas, USA.
| | - Jimmy D Gollihar
- Antibody Discovery and Accelerated Protein Therapeutics, Department of Pathology & Genomic Medicine, Houston Methodist Research Institute, Houston, Texas, USA.
| | - Andrew D Ellington
- Department of Molecular Biosciences, Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, Texas, USA.
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2
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Hayoz S, Jia C, Hegg CC. Constitutive and evoked release of ATP in adult mouse olfactory epithelium. Open Life Sci 2024; 19:20220811. [PMID: 38250473 PMCID: PMC10795008 DOI: 10.1515/biol-2022-0811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 10/31/2023] [Accepted: 11/28/2023] [Indexed: 01/23/2024] Open
Abstract
In adult olfactory epithelium (OE), ATP plays a role in constant cell turnover and post-injury neuroregeneration. We previously demonstrated that constitutive and ATP-evoked ATP release are present in neonatal mouse OE and underlie continuous cell turn-over and post-injury neuroregeneration, and that activation of purinergic P2X7 receptors is involved in the evoked release. We hypothesized that both releases are present in adult mouse OE. To study the putative contribution of olfactory sensory neurons to ATP release, we used olfactory sensory neuronal-like OP6 cells derived from the embryonic olfactory placode cells. Calcium imaging showed that OP6 cells and primary adult OE cell cultures express functional purinergic receptors. We monitored ATP release from OP6 cells and whole adult OE turbinates using HEK cells as biosensors and luciferin-luciferase assays. Constitutive ATP release occurs in OP6 cells and whole adult mouse OE turbinates, and P2X7 receptors mediated evoked ATP release occurs only in turbinates. The mechanisms of ATP release described in the present study might underlie the constant cell turn-over and post-injury neuroregeneration present in adult OE and thus, further studies of these mechanisms are warranted as it will improve our knowledge of OE tissue homeostasis and post-injury regeneration.
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Affiliation(s)
- Sébastien Hayoz
- Department of Physiology, University of Arizona, Tucson, Arizona 85724, USA
| | - Cuihong Jia
- Department of Biomedical Sciences, East Tennessee State University, Johnson City, Tennessee 37614, USA
| | - Colleen Cosgrove Hegg
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan 48824, USA
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3
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Kiaie SH, Hatami Z, Nasr MS, Pazooki P, Hemmati S, Baradaran B, Valizadeh H. Pharmacological interaction and immune response of purinergic receptors in therapeutic modulation. Purinergic Signal 2023:10.1007/s11302-023-09966-7. [PMID: 37843749 DOI: 10.1007/s11302-023-09966-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Accepted: 09/10/2023] [Indexed: 10/17/2023] Open
Abstract
Nucleosides and purine nucleotides serve as transmitter and modulator agents that extend their functions beyond the cell. In this context, purinergic signaling plays a crucial role in regulating energy homeostasis and modulating metabolic alterations in tumor cells. Therefore, it is essential to consider the pharmacological targeting of purinergic receptors (PUR), which encompass the expression and inhibition of P1 receptors (metabotropic adenosine receptors) as well as P2 receptors (extracellular ATP/ADP) comprising P2X and P2Y receptors. Thus, the pharmacological interaction between inhibitors (such as RNA, monoclonal antibodies, and small molecules) and PUR represents a key aspect in facilitating the development of therapeutic interventions. Moreover, this review explores recent advancements in pharmacological inhibitors and the regulation of innate and adaptive immunity of PUR, specifically in relation to immunological and inflammatory responses. These responses encompass the release of pro-inflammatory cytokines (PIC), the production of reactive oxygen and nitrogen species (ROS and RNS), the regulation of T cells, and the activation of inflammasomes in all human leukocytes.
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Affiliation(s)
- Seyed Hossein Kiaie
- Drug Applied Research Center, Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Zahra Hatami
- Department of Immunology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Mohammad Sadegh Nasr
- Department of Computer Science and Engineering Multi-Interprofessional Center for Health Informatics (MICHI), The University of Texas at Arlington, Arlington, TX, USA
| | - Pouya Pazooki
- Cellular and Molecular Biology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Salar Hemmati
- Institute Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Behzad Baradaran
- Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
| | - Hadi Valizadeh
- Drug Applied Research Center, Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran.
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4
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Doyle ME, Premathilake HU, Yao Q, Mazucanti CH, Egan JM. Physiology of the tongue with emphasis on taste transduction. Physiol Rev 2023; 103:1193-1246. [PMID: 36422992 PMCID: PMC9942923 DOI: 10.1152/physrev.00012.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The tongue is a complex multifunctional organ that interacts and senses both interoceptively and exteroceptively. Although it is easily visible to almost all of us, it is relatively understudied and what is in the literature is often contradictory or is not comprehensively reported. The tongue is both a motor and a sensory organ: motor in that it is required for speech and mastication, and sensory in that it receives information to be relayed to the central nervous system pertaining to the safety and quality of the contents of the oral cavity. Additionally, the tongue and its taste apparatus form part of an innate immune surveillance system. For example, loss or alteration in taste perception can be an early indication of infection as became evident during the present global SARS-CoV-2 pandemic. Here, we particularly emphasize the latest updates in the mechanisms of taste perception, taste bud formation and adult taste bud renewal, and the presence and effects of hormones on taste perception, review the understudied lingual immune system with specific reference to SARS-CoV-2, discuss nascent work on tongue microbiome, as well as address the effect of systemic disease on tongue structure and function, especially in relation to taste.
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Affiliation(s)
- Máire E Doyle
- Diabetes Section/Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Hasitha U Premathilake
- Diabetes Section/Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Qin Yao
- Diabetes Section/Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Caio H Mazucanti
- Diabetes Section/Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Josephine M Egan
- Diabetes Section/Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland
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5
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Vukmanovic Nosrat I, Palacios JL, Kezian S, Luong G, Tran A, Vu K, Henson BS, Nosrat P, Lutfy K, Nosrat CA. Brain-derived neurotrophic factor overexpression in taste buds diminishes chemotherapy induced taste loss. Eur J Neurosci 2022; 56:4967-4982. [PMID: 35986485 PMCID: PMC9804163 DOI: 10.1111/ejn.15799] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Revised: 08/10/2022] [Accepted: 08/11/2022] [Indexed: 01/05/2023]
Abstract
Vismodegib is used in patients suffering from advanced basal cell carcinoma (BCC), but 100% of the patients taking it report dysgeusia and 50% discontinue the treatment. Treatment with neurotrophic factors can stimulate neuronal survival and functional improvement in injured organs. Here, we analysed novel transgenic mouse lines in which brain-derived neurotrophic factor (BDNF) is overexpressed in taste buds, to examine whether higher levels of BDNF would reduce or prevent negative side effects of vismodegib in the taste system. BDNF plays crucial roles for development, target innervation, and survival of gustatory neurons and taste buds. The behavioural test in this study showed that vehicle-treated wild-type mice prefered 10 mM sucrose over water, whereas vismodegib treatment in wild-type mice caused total taste loss. Gustducin-BDNF mice had a significantly increased preference for low concentration of sucrose solution over water compared to wild-type mice, and most importantly the transgenic mice were able to detect low concentrations of sucrose following vismodegib treatment. We evaluated taste cell morphology, identity, innervation and proliferation using immunohistochemistry. All drug-treated mice exhibited deficits, but because of a possible functional upcycled priming of the peripheral gustatory system, GB mice demonstrated better morphological preservation of the peripheral gustatory system. Our study indicates that overexpression of BDNF in taste buds plays a role in preventing degeneration of taste buds. Counteracting the negative side effects of vismodegib treatment might improve compliance and achieve better outcome in patients suffering from advanced BCC.
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Affiliation(s)
| | - Jerry L. Palacios
- Graduate College of Biomedical SciencesWestern University of Health SciencesPomonaCaliforniaUSA
| | - Steven Kezian
- Graduate College of Biomedical SciencesWestern University of Health SciencesPomonaCaliforniaUSA
| | - Gloria Luong
- Graduate College of Biomedical SciencesWestern University of Health SciencesPomonaCaliforniaUSA
| | - Andrew Tran
- Graduate College of Biomedical SciencesWestern University of Health SciencesPomonaCaliforniaUSA
| | - Kim Vu
- Graduate College of Biomedical SciencesWestern University of Health SciencesPomonaCaliforniaUSA
| | - Bradley S. Henson
- College of Dental MedicineWestern University of Health SciencesPomonaCaliforniaUSA
| | - Philip Nosrat
- College of Dental MedicineWestern University of Health SciencesPomonaCaliforniaUSA
| | - Kabirullah Lutfy
- Department of Pharmaceutical Sciences, College of PharmacyWestern University of Health SciencesPomonaCaliforniaUSA
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Sweet Taste Signaling: The Core Pathways and Regulatory Mechanisms. Int J Mol Sci 2022; 23:ijms23158225. [PMID: 35897802 PMCID: PMC9329783 DOI: 10.3390/ijms23158225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 07/23/2022] [Accepted: 07/25/2022] [Indexed: 12/10/2022] Open
Abstract
Sweet taste, a proxy for sugar-derived calories, is an important driver of food intake, and animals have evolved robust molecular and cellular machinery for sweet taste signaling. The overconsumption of sugar-derived calories is a major driver of obesity and other metabolic diseases. A fine-grained appreciation of the dynamic regulation of sweet taste signaling mechanisms will be required for designing novel noncaloric sweeteners with better hedonic and metabolic profiles and improved consumer acceptance. Sweet taste receptor cells express at least two signaling pathways, one mediated by a heterodimeric G-protein coupled receptor encoded by taste 1 receptor members 2 and 3 (TAS1R2 + TAS1R3) genes and another by glucose transporters and the ATP-gated potassium (KATP) channel. Despite these important discoveries, we do not fully understand the mechanisms regulating sweet taste signaling. We will introduce the core components of the above sweet taste signaling pathways and the rationale for having multiple pathways for detecting sweet tastants. We will then highlight the roles of key regulators of the sweet taste signaling pathways, including downstream signal transduction pathway components expressed in sweet taste receptor cells and hormones and other signaling molecules such as leptin and endocannabinoids.
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Abstract
This review summarizes our understanding of ATP signaling in taste and describes new directions for research. ATP meets all requisite criteria to be considered a neurotransmitter: (1) presence in taste cells, as in all cells; (2) release upon appropriate taste stimulation; (3) binding to cognate purinergic receptors P2X2 and P2X3 on gustatory afferent neurons, and (4) after release, enzymatic degradation to adenosine and other nucleotides by the ectonucleotidase, NTPDase2, expressed on the Type I, glial-like cells in the taste bud. Importantly, double knockout of P2X2 and P2X3 or pharmacological inhibition of P2X3 abolishes transmission of all taste qualities. In Type II taste cells (those that respond to sweet, bitter, or umami stimuli), ATP is released non-vesicularly by a large conductance ion channel composed of CALHM1 and CALHM3, which form a so-called channel synapse at areas of contact with afferent taste nerve fibers. Although ATP release has been detected only from Type II cells, it is also required for the transmission of salty and sour stimuli, which are mediated primarily by the Type III taste cells. The source of the ATP required for Type III cell signaling to afferent fibers is still unclear and is a focus for future experiments. The ionotropic purinergic receptor, P2X3, is widely expressed on many sensory afferents and has been a therapeutic target for treating chronic cough and pain. However, its requirement for taste signaling has complicated efforts at treatment since patients given P2X3 antagonists report substantial disturbances of taste and become non-compliant.
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Affiliation(s)
- Sue Kinnamon
- Department of Otolaryngology, University of Colorado School of Medicine, Aurora, CO, USA.
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO, USA.
| | - Thomas Finger
- Department of Otolaryngology, University of Colorado School of Medicine, Aurora, CO, USA.
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO, USA.
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"Tripartite Synapses" in Taste Buds: A Role for Type I Glial-like Taste Cells. J Neurosci 2021; 41:9860-9871. [PMID: 34697094 DOI: 10.1523/jneurosci.1444-21.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 09/29/2021] [Accepted: 10/17/2021] [Indexed: 11/21/2022] Open
Abstract
In mammalian taste buds, Type I cells comprise half of all cells. These are termed "glial-like" based on morphologic and molecular features, but there are limited studies describing their function. We tested whether Type I cells sense chemosensory activation of adjacent chemosensory (i.e., Types II and III) taste bud cells, similar to synaptic glia. Using Gad2;;GCaMP3 mice of both sexes, we confirmed by immunostaining that, within taste buds, GCaMP expression is predominantly in Type I cells (with no Type II and ≈28% Type III cells expressing weakly). In dissociated taste buds, GCaMP+ Type I cells responded to bath-applied ATP (10-100 μm) but not to 5-HT (transmitters released by Type II or III cells, respectively). Type I cells also did not respond to taste stimuli (5 μm cycloheximide, 1 mm denatonium). In lingual slice preparations also, Type I cells responded to bath-applied ATP (10-100 μm). However, when taste buds in the slice were stimulated with bitter tastants (cycloheximide, denatonium, quinine), Type I cells responded robustly. Taste-evoked responses of Type I cells in the slice preparation were significantly reduced by desensitizing purinoceptors or by purinoceptor antagonists (suramin, PPADS), and were essentially eliminated by blocking synaptic ATP release (carbenoxolone) or degrading extracellular ATP (apyrase). Thus, taste-evoked release of afferent ATP from type II chemosensory cells, in addition to exciting gustatory afferent fibers, also activates glial-like Type I taste cells. We speculate that Type I cells sense chemosensory activation and that they participate in synaptic signaling, similarly to glial cells at CNS tripartite synapses.SIGNIFICANCE STATEMENT Most studies of taste buds view the chemosensitive excitable cells that express taste receptors as the sole mediators of taste detection and transmission to the CNS. Type I "glial-like" cells, with their ensheathing morphology, are mostly viewed as responsible for clearing neurotransmitters and as the "glue" holding the taste bud together. In the present study, we demonstrate that, when intact taste buds respond to their natural stimuli, Type I cells sense the activation of the chemosensory cells by detecting the afferent transmitter. Because Type I cells synthesize GABA, a known gliotransmitter, and cognate receptors are present on both presynaptic and postsynaptic elements, Type I cells may participate in GABAergic synaptic transmission in the manner of astrocytes at tripartite synapses.
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Rouadi PW, Idriss SA, Bousquet J, Laidlaw TM, Azar CR, Sulaiman AL-Ahmad M, Yáñez A, AL-Nesf MAY, Nsouli TM, Bahna SL, Abou-Jaoude E, Zaitoun FH, Hadi UM, Hellings PW, Scadding GK, Smith PK, Morais-Almeida M, Gómez RM, González Díaz SN, Klimek L, Juvelekian GS, Riachy MA, Canonica GW, Peden D, Wong GW, Sublett J, Bernstein JA, Wang L, Tanno LK, Chikhladze M, Levin M, Chang YS, Martin BL, Caraballo L, Custovic A, Ortega-Martell JA, Jensen-Jarolim E, Ebisawa M, Fiocchi A, Ansotegui IJ. WAO-ARIA consensus on chronic cough - Part 1: Role of TRP channels in neurogenic inflammation of cough neuronal pathways. World Allergy Organ J 2021; 14:100617. [PMID: 34934475 PMCID: PMC8654622 DOI: 10.1016/j.waojou.2021.100617] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 09/09/2021] [Accepted: 09/14/2021] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Cough features a complex peripheral and central neuronal network. The function of the chemosensitive and stretch (afferent) cough receptors is well described but partly understood. It is speculated that chronic cough reflects a neurogenic inflammation of the cough reflex, which becomes hypersensitive. This is mediated by neuromediators, cytokines, inflammatory cells, and a differential expression of neuronal (chemo/stretch) receptors, such as transient receptor potential (TRP) and purinergic P2X ion channels; yet the overall interaction of these mediators in neurogenic inflammation of cough pathways remains unclear. OBJECTIVES The World Allergy Organization/Allergic Rhinitis and its Impact on Asthma (WAO/ARIA) Joint Committee on Chronic Cough reviewed the current literature on neuroanatomy and pathophysiology of chronic cough. The role of TRP ion channels in pathogenic mechanisms of the hypersensitive cough reflex was also examined. OUTCOMES Chemoreceptors are better studied in cough neuronal pathways compared to stretch receptors, likely due to their anatomical overabundance in the respiratory tract, but also their distinctive functional properties. Central pathways are important in suppressive mechanisms and behavioral/affective aspects of chronic cough. Current evidence strongly suggests neurogenic inflammation induces a hypersensitive cough reflex marked by increased expression of neuromediators, mast cells, and eosinophils, among others. TRP ion channels, mainly TRP V1/A1, are important in the pathogenesis of chronic cough due to their role in mediating chemosensitivity to various endogenous and exogenous triggers, as well as a crosstalk between neurogenic and inflammatory pathways in cough-associated airways diseases.
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Affiliation(s)
- Philip W. Rouadi
- Department of Otolaryngology - Head and Neck Surgery, Eye and Ear University Hospital, Beirut, Lebanon
| | - Samar A. Idriss
- Department of Otolaryngology - Head and Neck Surgery, Eye and Ear University Hospital, Beirut, Lebanon
- Department of Audiology and Otoneurological Evaluation, Edouard Herriot Hospital, Lyon, France
| | - Jean Bousquet
- Hospital Charité, Universitätsmedizin Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
- Department of Dermatology and Allergy, Comprehensive Allergy Center, Berlin Institute of Health, Berlin, Germany
- Macvia France, Montpellier France
- Université Montpellier, Montpellier, France
| | - Tanya M. Laidlaw
- Department of Medicine, Harvard Medical School, Division of Allergy and Clinical Immunology, Brigham and Women's Hospital Boston, MA, USA
| | - Cecilio R. Azar
- Department of Gastroenterology, American University of Beirut Medical Center (AUBMC), Beirut, Lebanon
- Department of Gastroenterology, Middle East Institute of Health (MEIH), Beirut, Lebanon
- Department of Gastroenterology, Clemenceau Medical Center (CMC), Beirut, Lebanon
| | | | - Anahí Yáñez
- INAER - Investigaciones en Alergia y Enfermedades Respiratorias, Buenos Aires, Argentina
| | - Maryam Ali Y. AL-Nesf
- Allergy and Immunology Section, Department of Medicine, Hamad Medical Corporation, P.O. Box 3050, Doha, Qatar
| | | | - Sami L. Bahna
- Allergy & Immunology Section, Louisiana State University Health Sciences Center, Shreveport, LA, USA
| | | | - Fares H. Zaitoun
- Department of Allergy Otolaryngology, LAU-RIZK Medical Center, Beirut, Lebanon
| | - Usamah M. Hadi
- Clinical Professor Department of Otolaryngology Head and Neck Surgery, American University of Beirut, Lebanon
| | - Peter W. Hellings
- KU Leuven Department of Microbiology, Immunology and Transplantation, Laboratory of Allergy and Clinical Immunology, Leuven, Belgium
- University Hospitals Leuven, Department of Otorhinolaryngology, Leuven, Belgium
- University Hospital Ghent, Department of Otorhinolaryngology, Laboratory of Upper Airways Research, Ghent, Belgium
- Academic Medical Center, University of Amsterdam, Department of Otorhinolaryngology, Amsterdam, the Netherlands
| | | | - Peter K. Smith
- Clinical Medicine Griffith University, Southport Qld, 4215, Australia
| | | | | | - Sandra N. González Díaz
- Universidad Autónoma de Nuevo León, Hospital Universitario and Facultad de Medicina, Monterrey, Nuevo León, Mexico
| | - Ludger Klimek
- Center for Rhinology and Allergology, Wiesbaden, Germany
| | - Georges S. Juvelekian
- Department of Pulmonary, Critical Care and Sleep Medicine at Saint George Hospital University Medical Center, Beirut, Lebanon
| | - Moussa A. Riachy
- Department of Pulmonary and Critical Care, Hôtel-Dieu de France University Hospital, Beirut, Lebanon
| | - Giorgio Walter Canonica
- Humanitas University, Personalized Medicine Asthma & Allergy Clinic-Humanitas Research Hospital-IRCCS-Milano Italy
| | - David Peden
- UNC Center for Environmental Medicine, Asthma, and Lung Biology, Division of Allergy, Immunology and Rheumatology, Department of Pediatrics UNS School of Medicine, USA
| | - Gary W.K. Wong
- Department of Pediatrics, Chinese University of Hong Kong, Hong Kong, China
| | - James Sublett
- Department of Pediatrics, Section of Allergy and Immunology, University of Louisville School of Medicine, 9800 Shelbyville Rd, Louisville, KY, USA
| | - Jonathan A. Bernstein
- University of Cincinnati College of Medicine, Department of Internal Medicine, Division of Immunology/Allergy Section, Cincinnati
| | - Lianglu Wang
- Department of Allergy, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing Key Laboratory of Precision Medicine for Diagnosis and Treatment of Allergic Disease, State Key Laboratory of Complex Severe and Rare Diseases, National Clinical Research Center for Dermatologic and Immunologic Diseases (NCRC-DID), Beijing 100730, China
| | - Luciana Kase Tanno
- Université Montpellier, Montpellier, France
- Desbrest Institute of Epidemiology and Public Health, UMR UA-11, INSERM University of Montpellier, Montpellier, France
- WHO Collaborating Centre on Scientific Classification Support, Montpellier, France
| | - Manana Chikhladze
- Medical Faculty at Akaki Tsereteli State University, National Institute of Allergy, Asthma & Clinical Immunology, KuTaisi, Tskaltubo, Georgia
| | - Michael Levin
- Division of Paediatric Allergology, Department of Paediatrics, University of Cape Town, South Africa
| | - Yoon-Seok Chang
- Division of Allergy and Clinical Immunology, Department of Internal Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, South Korea
| | - Bryan L. Martin
- Department of Otolaryngology, Division of Allergy & Immunology, The Ohio State University, Columbus, OH, USA
| | - Luis Caraballo
- Institute for Immunological Research, University of Cartagena. Cartagena de Indias, Colombia
| | - Adnan Custovic
- National Heart and Lund Institute, Imperial College London, UK
| | | | - Erika Jensen-Jarolim
- Institute of Pathophysiology and Allergy Research, Center of Pathophysiology, Infectiology and Immunology, Medical University Vienna, Austria
- The Interuniversity Messerli Research Institute, Medical University Vienna and Univ, of Veterinary Medicine Vienna, Austria
| | - Motohiro Ebisawa
- Clinical Research Center for Allergy and Rheumatology,National Hospital Organization Sagamihara National Hospital, Sagamihara, Japan
| | - Alessandro Fiocchi
- Translational Pediatric Research Area, Allergic Diseases Research Unit, Bambino Gesù Children's Hospital IRCCS, Rome, Holy See
| | - Ignacio J. Ansotegui
- Department of Allergy and Immunology, Hospital Quironsalud Bizkaia, Bilbao, Spain
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10
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Finger T, Kinnamon S. Purinergic neurotransmission in the gustatory system. Auton Neurosci 2021; 236:102874. [PMID: 34536906 DOI: 10.1016/j.autneu.2021.102874] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 08/13/2021] [Accepted: 08/22/2021] [Indexed: 11/26/2022]
Abstract
Taste buds consist of specialized epithelial cells which detect particular tastants and synapse onto the afferent taste nerve innervating the endorgan. The nature of the neurotransmitter released by taste cells onto the nerve fiber was enigmatic early in this century although neurotransmitters for other sensory receptor cell types, e.g. hair cells, photoreceptors, was known for at least a decade. A 1999 paper by Burnstock and co-workers (Bo et al., 1999) showing the presence of P2X receptors on the afferent nerves served as a springboard for research that ultimately led to the discovery of ATP as the crucial neurotransmitter in the taste system (Finger et al., 2005). Subsequent work showed that a subpopulation of taste cells utilize a unique release channel, CALHM1/3, to release ATP in a voltage-dependent manner. Despite these advances, several aspects of purinergic transmission in this system remain to be elucidated.
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Affiliation(s)
- T Finger
- Dept. Cell & Developmental Biology, Dept. Otolaryngology, Univ. Colorado School of Medicine, Anschutz Medical Campus, MS 8108, Room L18-11118, RC-1, 12801 E. 17th Ave., Aurora, CO 80045, United States of America.
| | - Sue Kinnamon
- Dept. Cell & Developmental Biology, Dept. Otolaryngology, Univ. Colorado School of Medicine, Anschutz Medical Campus, MS 8108, Room L18-11118, RC-1, 12801 E. 17th Ave., Aurora, CO 80045, United States of America
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11
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Roper SD. Chemical and electrical synaptic interactions among taste bud cells. CURRENT OPINION IN PHYSIOLOGY 2021; 20:118-125. [PMID: 33521414 DOI: 10.1016/j.cophys.2020.12.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Chemical synapses between taste cells were first proposed based on electron microscopy of fish taste buds. Subsequently, researchers found considerable evidence for electrical coupling in fish, amphibian, and possibly mammalian taste buds. The development lingual slice and isolated cell preparations allowed detailed investigations of cell-cell interactions, both chemical and electrical, in taste buds. The identification of serotonin and ATP as taste neurotransmitters focused attention onto chemical synaptic interactions between taste cells and research on electrical coupling faded. Findings from Ca2+ imaging, electrophysiology, and molecular biology indicate that several neurotransmitters, including ATP, serotonin, GABA, acetylcholine, and norepinephrine, are secreted by taste cells and exert paracrine interactions in taste buds. Most work has been done on interactions between Type II and Type III taste cells. This brief review follows the trail of studies on cell-cell interactions in taste buds, from the initial ultrastructural observations to the most recent optogenetic manipulations.
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Affiliation(s)
- Stephen D Roper
- Department of Physiology & Biophysics and Department of Otolaryngology, Miller School of Medicine, University of Miami, FL 33136
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12
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Illes P, Müller CE, Jacobson KA, Grutter T, Nicke A, Fountain SJ, Kennedy C, Schmalzing G, Jarvis MF, Stojilkovic SS, King BF, Di Virgilio F. Update of P2X receptor properties and their pharmacology: IUPHAR Review 30. Br J Pharmacol 2020; 178:489-514. [PMID: 33125712 PMCID: PMC8199792 DOI: 10.1111/bph.15299] [Citation(s) in RCA: 164] [Impact Index Per Article: 41.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 10/20/2020] [Accepted: 10/22/2020] [Indexed: 12/20/2022] Open
Abstract
The known seven mammalian receptor subunits (P2X1–7) form cationic channels gated by ATP. Three subunits compose a receptor channel. Each subunit is a polypeptide consisting of two transmembrane regions (TM1 and TM2), intracellular N- and C-termini, and a bulky extracellular loop. Crystallization allowed the identification of the 3D structure and gating cycle of P2X receptors. The agonist-binding pocket is located at the intersection of two neighbouring subunits. In addition to the mammalian P2X receptors, their primitive ligand-gated counterparts with little structural similarity have also been cloned. Selective agonists for P2X receptor subtypes are not available, but medicinal chemistry supplied a range of subtype-selective antagonists, as well as positive and negative allosteric modulators. Knockout mice and selective antagonists helped to identify pathological functions due to defective P2X receptors, such as male infertility (P2X1), hearing loss (P2X2), pain/cough (P2X3), neuropathic pain (P2X4), inflammatory bone loss (P2X5), and faulty immune reactions (P2X7).
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Affiliation(s)
- Peter Illes
- Rudolf Boehm Institute for Pharmacology and Toxicology, University of Leipzig, Leipzig, Germany.,International Collaborative Centre on Big Science Plan for Purinergic Signalling, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Christa E Müller
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical & Medicinal Chemistry, University of Bonn, Bonn, Germany
| | - Kenneth A Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Thomas Grutter
- University of Strasbourg, Centre National de la Recherche Scientifique, CAMB UMR 7199, Strasbourg, France
| | - Annette Nicke
- Walther Straub Institute for Pharmacology and Toxicology, Ludwig-Maximilians-Universität München, Munich, Germany
| | | | - Charles Kennedy
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
| | - Günther Schmalzing
- Institute of Clinical Pharmacology, RWTH Aachen University, Aachen, Germany
| | | | - Stanko S Stojilkovic
- Section on Cellular Signaling, The Eunice Kennedy Shiver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Brian F King
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Francesco Di Virgilio
- Department of Medical Sciences, Section of Experimental Medicine, University of Ferrara, Ferrara, Italy
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13
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Kong Y, Wang Q, Wu DY, Hu J, Zang WS, Li XW, Yang JM, Gao TM. Involvement of P2X2 receptor in the medial prefrontal cortex in ATP modulation of the passive coping response to behavioral challenge. GENES BRAIN AND BEHAVIOR 2020; 19:e12691. [PMID: 32761745 DOI: 10.1111/gbb.12691] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 08/01/2020] [Accepted: 08/04/2020] [Indexed: 12/22/2022]
Abstract
P2X2 and P2X3 receptors are widely expressed in both the peripheral nervous system and the central nervous system and have been proven to participate in different peripheral sensory functions, but there are few studies on the involvement of P2X2 and P2X3 receptors in animal behaviors. Here we used P2X2 and P2X3 knockout mice to address this issue. P2X2 knockout mice showed normal motor function, exploratory behavior, anxiety-like behaviors, learning and memory behaviors and passive coping response to behavioral challenge. Nevertheless, the effect of ATP infusion in the medial prefrontal cortex (mPFC) on the passive coping response was blocked by P2X2 but not P2X3 receptor deletion. Additionally, no deficits in a wide variety of behavioral tests were observed in P2X3 knockout mice. These findings demonstrate a role of P2X2 receptor in the mPFC in adenosine-5'-triphosphate modulation of the passive coping response to behavioral challenge and show that the P2X2/P2X3 receptor is dispensable for behaviors.
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Affiliation(s)
- Ying Kong
- State Key Laboratory of Organ Failure Research, Key Laboratory of Mental Health of the Ministry of Education, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Key Laboratory of Psychiatric Disorders of Guangdong Province, Collaborative Innovation Center for Brain Science, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Qian Wang
- State Key Laboratory of Organ Failure Research, Key Laboratory of Mental Health of the Ministry of Education, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Key Laboratory of Psychiatric Disorders of Guangdong Province, Collaborative Innovation Center for Brain Science, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Ding-Yu Wu
- State Key Laboratory of Organ Failure Research, Key Laboratory of Mental Health of the Ministry of Education, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Key Laboratory of Psychiatric Disorders of Guangdong Province, Collaborative Innovation Center for Brain Science, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Jian Hu
- State Key Laboratory of Organ Failure Research, Key Laboratory of Mental Health of the Ministry of Education, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Key Laboratory of Psychiatric Disorders of Guangdong Province, Collaborative Innovation Center for Brain Science, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Wen-Si Zang
- State Key Laboratory of Organ Failure Research, Key Laboratory of Mental Health of the Ministry of Education, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Key Laboratory of Psychiatric Disorders of Guangdong Province, Collaborative Innovation Center for Brain Science, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Xiao-Wen Li
- State Key Laboratory of Organ Failure Research, Key Laboratory of Mental Health of the Ministry of Education, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Key Laboratory of Psychiatric Disorders of Guangdong Province, Collaborative Innovation Center for Brain Science, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Jian-Ming Yang
- State Key Laboratory of Organ Failure Research, Key Laboratory of Mental Health of the Ministry of Education, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Key Laboratory of Psychiatric Disorders of Guangdong Province, Collaborative Innovation Center for Brain Science, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Tian-Ming Gao
- State Key Laboratory of Organ Failure Research, Key Laboratory of Mental Health of the Ministry of Education, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Key Laboratory of Psychiatric Disorders of Guangdong Province, Collaborative Innovation Center for Brain Science, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
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14
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Development of a Mouse Reporter Strain for the Purinergic P2X 2 Receptor. eNeuro 2020; 7:ENEURO.0203-20.2020. [PMID: 32669344 PMCID: PMC7418537 DOI: 10.1523/eneuro.0203-20.2020] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 06/23/2020] [Accepted: 07/03/2020] [Indexed: 02/06/2023] Open
Abstract
The ATP-sensitive P2X2 ionotropic receptor plays a critical role in a number of signal processes including taste and hearing, carotid body detection of hypoxia, the exercise pressor reflex and sensory transduction of mechanical stimuli in the airways and bladder. Elucidation of the role of P2X2 has been hindered by the lack of selective tools. In particular, detection of P2X2 using established pharmacological and biochemical techniques yields dramatically different expression patterns, particularly in the peripheral and central nervous systems. Here, we have developed a knock-in P2X2-cre mouse, which we crossed with a cre-sensitive tdTomato reporter mouse to determine P2X2 expression. P2X2 was found in more than 80% of nodose vagal afferent neurons, but not in jugular vagal afferent neurons. Reporter expression correlated in vagal neurons with sensitivity to α,β methylene ATP (αβmATP). P2X2 was expressed in 75% of petrosal afferents, but only 12% and 4% of dorsal root ganglia (DRG) and trigeminal afferents, respectively. P2X2 expression was limited to very few cell types systemically. Together with the central terminals of P2X2-expressing afferents, reporter expression in the CNS was mainly found in brainstem neurons projecting mossy fibers to the cerebellum, with little expression in the hippocampus or cortex. The structure of peripheral terminals of P2X2-expressing afferents was demonstrated in the tongue (taste buds), carotid body, trachea and esophagus. P2X2 was observed in hair cells and support cells in the cochlear, but not in spiral afferent neurons. This mouse strain provides a novel approach to the identification and manipulation of P2X2-expressing cell types.
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15
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Stokes L, Bidula S, Bibič L, Allum E. To Inhibit or Enhance? Is There a Benefit to Positive Allosteric Modulation of P2X Receptors? Front Pharmacol 2020; 11:627. [PMID: 32477120 PMCID: PMC7235284 DOI: 10.3389/fphar.2020.00627] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 04/21/2020] [Indexed: 12/15/2022] Open
Abstract
The family of ligand-gated ion channels known as P2X receptors were discovered several decades ago. Since the cloning of the seven P2X receptors (P2X1-P2X7), a huge research effort has elucidated their roles in regulating a range of physiological and pathophysiological processes. Transgenic animals have been influential in understanding which P2X receptors could be new therapeutic targets for disease. Furthermore, understanding how inherited mutations can increase susceptibility to disorders and diseases has advanced this knowledge base. There has been an emphasis on the discovery and development of pharmacological tools to help dissect the individual roles of P2X receptors and the pharmaceutical industry has been involved in pushing forward clinical development of several lead compounds. During the discovery phase, a number of positive allosteric modulators have been described for P2X receptors and these have been useful in assigning physiological roles to receptors. This review will consider the major physiological roles of P2X1-P2X7 and discuss whether enhancement of P2X receptor activity would offer any therapeutic benefit. We will review what is known about identified compounds acting as positive allosteric modulators and the recent identification of drug binding pockets for such modulators.
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Affiliation(s)
- Leanne Stokes
- School of Pharmacy, University of East Anglia, Norwich, United Kingdom
| | - Stefan Bidula
- School of Pharmacy, University of East Anglia, Norwich, United Kingdom
| | - Lučka Bibič
- School of Pharmacy, University of East Anglia, Norwich, United Kingdom
| | - Elizabeth Allum
- School of Pharmacy, University of East Anglia, Norwich, United Kingdom
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16
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Huang AY. Immune Responses Alter Taste Perceptions: Immunomodulatory Drugs Shape Taste Signals during Treatments. J Pharmacol Exp Ther 2019; 371:684-691. [PMID: 31611237 DOI: 10.1124/jpet.119.261297] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 10/08/2019] [Indexed: 01/01/2023] Open
Abstract
Considering that nutrients are required in health and diseases, the detection and ingestion of food to meet the requirements is attributable to the sense of taste. Altered taste sensations lead to a decreased appetite, which is usually one of the frequent causes of malnutrition in patients with diseases. Ongoing taste research has identified a variety of drug pathways that cause changes in taste perceptions in cancer, increasing our understanding of taste disturbances attributable to aberrant mechanisms of taste sensation. The evidence discussed in this review, which addresses the implications of innate immune responses in the modulation of taste functions, focuses on the adverse effects on taste transmission from taste buds by immune modulators responsible for alterations in the perceived intensity of some taste modalities. Another factor, damage to taste progenitor cells that directly results in local effects on taste buds, must also be considered in relation to taste disturbances in patients with cancer. Recent discoveries discussed have provided new insights into the pathophysiology of taste dysfunctions associated with the specific treatments. SIGNIFICANCE STATEMENT: The paradigm that taste signals transmitted to the brain are determined only by tastant-mediated activation via taste receptors has been challenged by the immune modification of taste transmission through drugs during the processing of gustatory information in taste buds. This article reports the findings in a model system (mouse taste buds) that explain the basis for the taste dysfunctions in patients with cancer that has long been observed but never understood.
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Affiliation(s)
- Anthony Y Huang
- Department of Anatomy and Center for Integrated Research in Cognitive and Neural Science, Southern Illinois University School of Medicine, Carbondale, Illinois
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17
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Zhang J, Jin H, Zhang W, Ding C, O'Keeffe S, Ye M, Zuker CS. Sour Sensing from the Tongue to the Brain. Cell 2019; 179:392-402.e15. [PMID: 31543264 DOI: 10.1016/j.cell.2019.08.031] [Citation(s) in RCA: 132] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Revised: 08/04/2019] [Accepted: 08/15/2019] [Indexed: 12/19/2022]
Abstract
The ability to sense sour provides an important sensory signal to prevent the ingestion of unripe, spoiled, or fermented foods. Taste and somatosensory receptors in the oral cavity trigger aversive behaviors in response to acid stimuli. Here, we show that the ion channel Otopetrin-1, a proton-selective channel normally involved in the sensation of gravity in the vestibular system, is essential for sour sensing in the taste system. We demonstrate that knockout of Otop1 eliminates acid responses from sour-sensing taste receptor cells (TRCs). In addition, we show that mice engineered to express otopetrin-1 in sweet TRCs have sweet cells that also respond to sour stimuli. Next, we genetically identified the taste ganglion neurons mediating each of the five basic taste qualities and demonstrate that sour taste uses its own dedicated labeled line from TRCs in the tongue to finely tuned taste neurons in the brain to trigger aversive behaviors.
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Affiliation(s)
- Jin Zhang
- Howard Hughes Medical Institute, Columbia University, New York, NY 10032, USA; Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; Department of Neuroscience, Columbia University, New York, NY 10032, USA; Mortimer B. Zukerman Mind Brain and Behavior Institute, Columbia University, New York, NY 10027, USA
| | - Hao Jin
- Howard Hughes Medical Institute, Columbia University, New York, NY 10032, USA; Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; Department of Neuroscience, Columbia University, New York, NY 10032, USA; Mortimer B. Zukerman Mind Brain and Behavior Institute, Columbia University, New York, NY 10027, USA
| | - Wenyi Zhang
- Howard Hughes Medical Institute, Columbia University, New York, NY 10032, USA; Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; Department of Neuroscience, Columbia University, New York, NY 10032, USA; Mortimer B. Zukerman Mind Brain and Behavior Institute, Columbia University, New York, NY 10027, USA
| | - Cheng Ding
- Howard Hughes Medical Institute, Columbia University, New York, NY 10032, USA; Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; Department of Neuroscience, Columbia University, New York, NY 10032, USA; Mortimer B. Zukerman Mind Brain and Behavior Institute, Columbia University, New York, NY 10027, USA
| | - Sean O'Keeffe
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Mingyu Ye
- Howard Hughes Medical Institute, Columbia University, New York, NY 10032, USA; Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; Department of Neuroscience, Columbia University, New York, NY 10032, USA; Mortimer B. Zukerman Mind Brain and Behavior Institute, Columbia University, New York, NY 10027, USA
| | - Charles S Zuker
- Howard Hughes Medical Institute, Columbia University, New York, NY 10032, USA; Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA; Department of Neuroscience, Columbia University, New York, NY 10032, USA; Mortimer B. Zukerman Mind Brain and Behavior Institute, Columbia University, New York, NY 10027, USA.
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18
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Li M, Wang Y, Banerjee R, Marinelli F, Silberberg S, Faraldo-Gómez JD, Hattori M, Swartz KJ. Molecular mechanisms of human P2X3 receptor channel activation and modulation by divalent cation bound ATP. eLife 2019; 8:47060. [PMID: 31232692 PMCID: PMC6590987 DOI: 10.7554/elife.47060] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 06/06/2019] [Indexed: 01/01/2023] Open
Abstract
P2X3 receptor channels expressed in sensory neurons are activated by extracellular ATP and serve important roles in nociception and sensory hypersensitization, making them attractive therapeutic targets. Although several P2X3 structures are known, it is unclear how physiologically abundant Ca2+-ATP and Mg2+-ATP activate the receptor, or how divalent cations regulate channel function. We used structural, computational and functional approaches to show that a crucial acidic chamber near the nucleotide-binding pocket in human P2X3 receptors accommodates divalent ions in two distinct modes in the absence and presence of nucleotide. The unusual engagement between the receptor, divalent ion and the γ-phosphate of ATP enables channel activation by ATP-divalent complex, cooperatively stabilizes the nucleotide on the receptor to slow ATP unbinding and recovery from desensitization, a key mechanism for limiting channel activity. These findings reveal how P2X3 receptors recognize and are activated by divalent-bound ATP, aiding future physiological investigations and drug development.
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Affiliation(s)
- Mufeng Li
- Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
| | - Yao Wang
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Multiscale Research Institute for Complex Systems, Department of Physiology and Biophysics, School of Life Sciences, Fudan University, Shanghai, China
| | - Rahul Banerjee
- Theoretical Molecular Biophysics Laboratory, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, United States
| | - Fabrizio Marinelli
- Theoretical Molecular Biophysics Laboratory, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, United States
| | - Shai Silberberg
- Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
| | - José D Faraldo-Gómez
- Theoretical Molecular Biophysics Laboratory, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, United States
| | - Motoyuki Hattori
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Multiscale Research Institute for Complex Systems, Department of Physiology and Biophysics, School of Life Sciences, Fudan University, Shanghai, China
| | - Kenton Jon Swartz
- Molecular Physiology and Biophysics Section, Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
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19
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Garceau D, Chauret N. BLU-5937: A selective P2X3 antagonist with potent anti-tussive effect and no taste alteration. Pulm Pharmacol Ther 2019; 56:56-62. [DOI: 10.1016/j.pupt.2019.03.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 01/17/2019] [Accepted: 03/17/2019] [Indexed: 12/21/2022]
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20
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Luddi A, Governini L, Wilmskötter D, Gudermann T, Boekhoff I, Piomboni P. Taste Receptors: New Players in Sperm Biology. Int J Mol Sci 2019; 20:E967. [PMID: 30813355 PMCID: PMC6413048 DOI: 10.3390/ijms20040967] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 02/13/2019] [Accepted: 02/18/2019] [Indexed: 12/21/2022] Open
Abstract
Taste receptors were first described as sensory receptors located on the tongue, where they are expressed in small clusters of specialized epithelial cells. However, more studies were published in recent years pointing to an expression of these proteins not only in the oral cavity but throughout the body and thus to a physiological role beyond the tongue. The recent observation that taste receptors and components of the coupled taste transduction cascade are also expressed during the different phases of spermatogenesis as well as in mature spermatozoa from mouse to humans and the overlap between the ligand spectrum of taste receptors with compounds in the male and female reproductive organs makes it reasonable to assume that sperm "taste" these different cues in their natural microenvironments. This assumption is assisted by the recent observations of a reproductive phenotype of different mouse lines carrying a targeted deletion of a taste receptor gene as well as the finding of a significant correlation between human male infertility and some polymorphisms in taste receptors genes. In this review, we depict recent findings on the role of taste receptors in male fertility, especially focusing on their possible involvement in mechanisms underlying spermatogenesis and post testicular sperm maturation. We also highlight the impact of genetic deletions of taste receptors, as well as their polymorphisms on male reproduction.
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Affiliation(s)
- Alice Luddi
- Department of Molecular and Developmental Medicine, Siena University, 53100 Siena, Italy.
| | - Laura Governini
- Department of Molecular and Developmental Medicine, Siena University, 53100 Siena, Italy.
| | - Dorke Wilmskötter
- Walther-Straub-Institute of Pharmacology and Toxicology, Ludwig-Maximilians-University, 80539 Munich, Germany.
| | - Thomas Gudermann
- Walther-Straub-Institute of Pharmacology and Toxicology, Ludwig-Maximilians-University, 80539 Munich, Germany.
| | - Ingrid Boekhoff
- Walther-Straub-Institute of Pharmacology and Toxicology, Ludwig-Maximilians-University, 80539 Munich, Germany.
| | - Paola Piomboni
- Department of Molecular and Developmental Medicine, Siena University, 53100 Siena, Italy.
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21
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Winkelmann VE, Thompson KE, Neuland K, Jaramillo AM, Fois G, Schmidt H, Wittekindt OH, Han W, Tuvim MJ, Dickey BF, Dietl P, Frick M. Inflammation-induced upregulation of P2X 4 expression augments mucin secretion in airway epithelia. Am J Physiol Lung Cell Mol Physiol 2018; 316:L58-L70. [PMID: 30358443 DOI: 10.1152/ajplung.00157.2018] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Mucus clearance provides an essential innate defense mechanism to keep the airways and lungs free of particles and pathogens. Baseline and stimulated mucin secretion from secretory airway epithelial cells need to be tightly regulated to prevent mucus hypersecretion and mucus plugging of the airways. It is well established that extracellular ATP is a potent stimulus for regulated mucus secretion. Previous studies revealed that ATP acts via metabotropic P2Y2 purinoreceptors on goblet cells. Extracellular ATP, however, is also a potent agonist for ionotropic P2X purinoreceptors. Expression of several P2X isoforms has been reported in airways, but cell type-specific expression and the function thereof remained elusive. With this study, we now provide evidence that P2X4 is the predominant P2X isoform expressed in secretory airway epithelial cells. After IL-13 treatment of either human primary tracheal epithelial cells or mice, P2X4 expression is upregulated in vitro and in vivo under conditions of chronic inflammation, mucous metaplasia, and hyperplasia. Upregulation of P2X4 is strongest in MUC5AC-positive goblet cells. Moreover, activation of P2X4 by extracellular ATP augments intracellular Ca2+ signals and mucin secretion, whereas Ca2+ signals and mucin secretion are dampened by inhibition of P2X4 receptors. These data provide new insights into the purinergic regulation of mucin secretion and add to the emerging picture that P2X receptors modulate exocytosis of large secretory organelles and secretion of macromolecular vesicle cargo.
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Affiliation(s)
| | - Kristin E Thompson
- Centre de Recherche Saint-Antoine, INSERM, Université Pierre et Marie Curie-Université Paris 06, Sorbonne Universités, Paris , France
| | - Kathrin Neuland
- Institute of General Physiology, Ulm University , Ulm , Germany
| | - Ana M Jaramillo
- Department of Pulmonary Medicine, MD Anderson Cancer Center , Houston, Texas
| | - Giorgio Fois
- Institute of General Physiology, Ulm University , Ulm , Germany
| | - Hanna Schmidt
- Institute of General Physiology, Ulm University , Ulm , Germany
| | | | - Wei Han
- Department of Pulmonary Medicine, MD Anderson Cancer Center , Houston, Texas
| | - Michael J Tuvim
- Department of Pulmonary Medicine, MD Anderson Cancer Center , Houston, Texas
| | - Burton F Dickey
- Department of Pulmonary Medicine, MD Anderson Cancer Center , Houston, Texas
| | - Paul Dietl
- Institute of General Physiology, Ulm University , Ulm , Germany
| | - Manfred Frick
- Institute of General Physiology, Ulm University , Ulm , Germany
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22
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Schroer AB, Gross JD, Kaski SW, Wix K, Siderovski DP, Vandenbeuch A, Setola V. Development of Full Sweet, Umami, and Bitter Taste Responsiveness Requires Regulator of G protein Signaling-21 (RGS21). Chem Senses 2018; 43:367-378. [PMID: 29701767 PMCID: PMC6276893 DOI: 10.1093/chemse/bjy024] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The mammalian tastes of sweet, umami, and bitter are initiated by activation of G protein-coupled receptors (GPCRs) of the T1R and T2R families on taste receptor cells. GPCRs signal via nucleotide exchange and hydrolysis, the latter hastened by GTPase-accelerating proteins (GAPs) that include the Regulators of G protein Signaling (RGS) protein family. We previously reported that RGS21, uniquely expressed in Type II taste receptor cells, decreases the potency of bitter-stimulated T2R signaling in cultured cells, consistent with its in vitro GAP activity. However, the role of RGS21 in organismal responses to GPCR-mediated tastants was not established. Here, we characterized mice lacking the Rgs21 fifth exon. Eliminating Rgs21 expression had no effect on body mass accumulation (a measure of alimentation), fungiform papillae number and morphology, circumvallate papillae morphology, and taste bud number. Two-bottle preference tests, however, revealed that Rgs21-null mice have blunted aversion to quinine and denatonium, and blunted preference for monosodium glutamate, the sweeteners sucrose and SC45647, and (surprisingly) NaCl. Observed reductions in GPCR-mediated tastant responses upon Rgs21 loss are opposite to original expectations, given that loss of RGS21-a GPCR signaling negative regulator-should lead to increased responsiveness to tastant-mediated GPCR signaling (all else being equal). Yet, reduced organismal tastant responses are consistent with observations of reduced chorda tympani nerve recordings in Rgs21-null mice. Reduced tastant-mediated responses and behaviors exhibited by adult mice lacking Rgs21 expression since birth have thus revealed an underappreciated requirement for a GPCR GAP to establish the full character of tastant signaling.
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Affiliation(s)
- Adam B Schroer
- Department of Physiology, Pharmacology, and Neuroscience, West Virginia School of Medicine, One Medical Center Drive, Morgantown, WV, USA
| | - Joshua D Gross
- Department of Physiology, Pharmacology, and Neuroscience, West Virginia School of Medicine, One Medical Center Drive, Morgantown, WV, USA
| | - Shane W Kaski
- Department of Physiology, Pharmacology, and Neuroscience, West Virginia School of Medicine, One Medical Center Drive, Morgantown, WV, USA
| | - Kim Wix
- Department of Physiology, Pharmacology, and Neuroscience, West Virginia School of Medicine, One Medical Center Drive, Morgantown, WV, USA
| | - David P Siderovski
- Department of Physiology, Pharmacology, and Neuroscience, West Virginia School of Medicine, One Medical Center Drive, Morgantown, WV, USA
| | - Aurelie Vandenbeuch
- Department of Otolaryngology, University of Colorado - Denver, Anschutz Medical Campus, Aurora, CO, USA
| | - Vincent Setola
- Department of Physiology, Pharmacology, and Neuroscience, West Virginia School of Medicine, One Medical Center Drive, Morgantown, WV, USA
- Department of Behavioral Medicine and Psychiatry, West Virginia School of Medicine, Morgantown, WV, USA
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CALHM3 Is Essential for Rapid Ion Channel-Mediated Purinergic Neurotransmission of GPCR-Mediated Tastes. Neuron 2018; 98:547-561.e10. [PMID: 29681531 DOI: 10.1016/j.neuron.2018.03.043] [Citation(s) in RCA: 109] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2017] [Revised: 02/26/2018] [Accepted: 03/26/2018] [Indexed: 11/21/2022]
Abstract
Binding of sweet, umami, and bitter tastants to G protein-coupled receptors (GPCRs) in apical membranes of type II taste bud cells (TBCs) triggers action potentials that activate a voltage-gated nonselective ion channel to release ATP to gustatory nerves mediating taste perception. Although calcium homeostasis modulator 1 (CALHM1) is necessary for ATP release, the molecular identification of the channel complex that provides the conductive ATP-release mechanism suitable for action potential-dependent neurotransmission remains to be determined. Here we show that CALHM3 interacts with CALHM1 as a pore-forming subunit in a CALHM1/CALHM3 hexameric channel, endowing it with fast voltage-activated gating identical to that of the ATP-release channel in vivo. Calhm3 is co-expressed with Calhm1 exclusively in type II TBCs, and its genetic deletion abolishes taste-evoked ATP release from taste buds and GPCR-mediated taste perception. Thus, CALHM3, together with CALHM1, is essential to form the fast voltage-gated ATP-release channel in type II TBCs required for GPCR-mediated tastes.
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Huang AY, Wu SY. Substance P as a putative efferent transmitter mediates GABAergic inhibition in mouse taste buds. Br J Pharmacol 2018; 175:1039-1053. [PMID: 29328505 DOI: 10.1111/bph.14142] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 11/21/2017] [Accepted: 12/23/2017] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND AND PURPOSE Capsaicin-mediated modulation of taste nerve responses is thought to be produced indirectly by the actions of neuropeptides, for example, CGRP and substance P (SP), on taste cells implying they play a role in taste sensitivity. During the processing of gustatory information in taste buds, CGRP shapes peripheral taste signals via serotonergic signalling. The underlying assumption has been that SP exerts its effects on taste transmitter secretion in taste buds of mice. EXPERIMENTAL APPROACH To test this assumption, we investigated the net effect of SP on taste-evoked ATP secretion from mouse taste buds, using functional calcium imaging with CHO cells expressing high-affinity transmitter receptors as cellular biosensors. KEY RESULTS Our results showed that SP elicited PLC activation-dependent intracellular Ca2+ transients in taste cells via neurokinin 1 receptors, most likely on glutamate-aspartate transporter-expressing Type I cells. Furthermore, SP caused Type I cells to secrete GABA. CONCLUSION AND IMPLICATIONS Combined with the recent findings that GABA depresses taste-evoked ATP secretion, the current results indicate that SP elicited secretion of GABA, which provided negative feedback onto Type II (receptor) cells to reduce taste-evoked ATP secretion. These findings are consistent with a role for SP as an inhibitory transmitter that shapes the peripheral taste signals, via GABAergic signalling, during the processing of gustatory information in taste buds. Notably, the results suggest that SP is intimately associated with GABA in mammalian taste signal processing and demonstrate an unanticipated route for sensory information flow within the taste bud.
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Affiliation(s)
- Anthony Y Huang
- Department of Anatomy, Southern Illinois University School of Medicine, Carbondale, IL, USA.,Center for Integrated Research in Cognitive and Neural Science, Southern Illinois University School of Medicine, Carbondale, IL, USA
| | - Sandy Y Wu
- Department of Anatomy, Southern Illinois University School of Medicine, Carbondale, IL, USA
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CALHM1-Mediated ATP Release and Ciliary Beat Frequency Modulation in Nasal Epithelial Cells. Sci Rep 2017; 7:6687. [PMID: 28751666 PMCID: PMC5532211 DOI: 10.1038/s41598-017-07221-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 06/23/2017] [Indexed: 12/21/2022] Open
Abstract
Mechanical stimulation of airway epithelial cells causes apical release of ATP, which increases ciliary beat frequency (CBF) and speeds up mucociliary clearance. The mechanisms responsible for this ATP release are poorly understood. CALHM1, a transmembrane protein with shared structural features to connexins and pannexins, has been implicated in ATP release from taste buds, but it has not been evaluated for a functional role in the airway. In the present study, Calhm1 knockout, Panx1 knockout, and wild-type mouse nasal septal epithelial cells were grown at an air-liquid interface (ALI) and subjected to light mechanical stimulation from an air puff. Apical ATP release was attenuated in Calhm1 knockout cultures following mechanical stimulation at a pressure of 55 mmHg for 50 milliseconds (p < 0.05). Addition of carbenoxolone, a PANX1 channel blocker, completely abolished ATP release in Calhm1 knockout cultures but not in wild type or Panx1 knockout cultures. An increase in CBF was observed in wild-type ALIs following mechanical stimulation, and this increase was significantly lower (p < 0.01) in Calhm1 knockout cultures. These results demonstrate that CALHM1 plays a newly defined role, complementary to PANX1, in ATP release and downstream CBF modulation following a mechanical stimulus in airway epithelial cells.
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Abstract
The past decade has witnessed a consolidation and refinement of the extraordinary progress made in taste research. This Review describes recent advances in our understanding of taste receptors, taste buds, and the connections between taste buds and sensory afferent fibres. The article discusses new findings regarding the cellular mechanisms for detecting tastes, new data on the transmitters involved in taste processing and new studies that address longstanding arguments about taste coding.
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Bigiani A. Calcium Homeostasis Modulator 1-Like Currents in Rat Fungiform Taste Cells Expressing Amiloride-Sensitive Sodium Currents. Chem Senses 2017; 42:343-359. [DOI: 10.1093/chemse/bjx013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Huang AY, Wu SY. The effect of imiquimod on taste bud calcium transients and transmitter secretion. Br J Pharmacol 2016; 173:3121-3133. [PMID: 27464850 DOI: 10.1111/bph.13567] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 07/07/2016] [Accepted: 07/19/2016] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND AND PURPOSE Imiquimod is an immunomodulator approved for the treatment of basal cell carcinoma and has adverse side effects, including taste disturbances. Paracrine transmission, representing cell-cell communication within taste buds, has the potential to shape the final signals that taste buds transmit to the brain. Here, we tested the underlying assumption that imiquimod modifies taste transmitter secretion in taste buds of mice. EXPERIMENTAL APPROACH Taste buds were isolated from C57BL/6J mice. The effects of imiquimod on transmitter release in taste buds were measured using calcium imaging with cellular biosensors, and examining the net effect of imiquimod on taste-evoked ATP secretion from mouse taste buds. KEY RESULTS Up to 72% of presynaptic (Type III) taste cells responded to 100 μM imiquimod with an increase in intracellular Ca2+ concentrations. These Ca2+ responses were inhibited by thapsigargin, an inhibitor of the sarco/endoplasmic reticulum Ca2+ -ATPase, and by U73122, a PLC inhibitor, suggesting that the Ca2+ mobilization elicited by imiquimod was dependent on release from internal Ca2+ stores. Moreover, combining studies of Ca2+ imaging with cellular biosensors showed that imiquimod evoked secretion of 5-HT, which then provided negative feedback onto receptor (Type II) cells to reduce taste-evoked ATP secretion. CONCLUSION AND IMPLICATIONS Our results provide evidence that there is a subset of taste cells equipped with a range of intracellular mechanisms that respond to imiquimod. The findings are also consistent with a role of imiquimod as an immune response modifier, which shapes peripheral taste responses via 5-HT signalling.
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Affiliation(s)
- Anthony Y Huang
- Department of Anatomy, Southern Illinois University School of Medicine, Carbondale, IL, USA. .,Center for Integrated Research in Cognitive and Neural Science, Southern Illinois University School of Medicine, Carbondale, IL, USA.
| | - Sandy Y Wu
- Department of Anatomy, Southern Illinois University School of Medicine, Carbondale, IL, USA
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Loper HB, La Sala M, Dotson C, Steinle N. Taste perception, associated hormonal modulation, and nutrient intake. Nutr Rev 2016; 73:83-91. [PMID: 26024495 DOI: 10.1093/nutrit/nuu009] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
It is well known that taste perception influences food intake. After ingestion, gustatory receptors relay sensory signals to the brain, which segregates, evaluates, and distinguishes the stimuli, leading to the experience known as "flavor." It is well accepted that five taste qualities – sweet, salty, bitter, sour, and umami – can be perceived by animals. In this review, the anatomy and physiology of human taste buds, the hormonal modulation of taste function, the importance of genetic chemosensory variation, and the influence of gustatory functioning on macronutrient selection and eating behavior are discussed. Individual genotypic variation results in specific phenotypes of food preference and nutrient intake. Understanding the role of taste in food selection and ingestive behavior is important for expanding our understanding of the factors involved in body weight maintenance and the risk of chronic diseases including obesity, atherosclerosis, cancer, diabetes, liver disease, and hypertension.
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Affiliation(s)
- Hillary B Loper
- H.B. Loper is with the Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA. M. La Sala and C. Dotson are with the Division of Addiction Medicine, Center for Smell and Taste, Department of Neuroscience and Psychiatry, University of Florida College of Medicine, Gainesville, FL, USA. N Steinle is with the Baltimore Veterans Administration Medical Center and University of Maryland School of Medicine, Baltimore, MD, USA
| | - Michael La Sala
- H.B. Loper is with the Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA. M. La Sala and C. Dotson are with the Division of Addiction Medicine, Center for Smell and Taste, Department of Neuroscience and Psychiatry, University of Florida College of Medicine, Gainesville, FL, USA. N Steinle is with the Baltimore Veterans Administration Medical Center and University of Maryland School of Medicine, Baltimore, MD, USA
| | - Cedrick Dotson
- H.B. Loper is with the Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA. M. La Sala and C. Dotson are with the Division of Addiction Medicine, Center for Smell and Taste, Department of Neuroscience and Psychiatry, University of Florida College of Medicine, Gainesville, FL, USA. N Steinle is with the Baltimore Veterans Administration Medical Center and University of Maryland School of Medicine, Baltimore, MD, USA
| | - Nanette Steinle
- H.B. Loper is with the Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA. M. La Sala and C. Dotson are with the Division of Addiction Medicine, Center for Smell and Taste, Department of Neuroscience and Psychiatry, University of Florida College of Medicine, Gainesville, FL, USA. N Steinle is with the Baltimore Veterans Administration Medical Center and University of Maryland School of Medicine, Baltimore, MD, USA
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Calcitonin Gene-Related Peptide Reduces Taste-Evoked ATP Secretion from Mouse Taste Buds. J Neurosci 2016; 35:12714-24. [PMID: 26377461 DOI: 10.1523/jneurosci.0100-15.2015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
UNLABELLED Immunoelectron microscopy revealed that peripheral afferent nerve fibers innervating taste buds contain calcitonin gene-related peptide (CGRP), which may be as an efferent transmitter released from peripheral axon terminals. In this report, we determined the targets of CGRP within taste buds and studied what effect CGRP exerts on taste bud function. We isolated mouse taste buds and taste cells, conducted functional imaging using Fura-2, and used cellular biosensors to monitor taste-evoked transmitter release. The findings showed that a subset of Presynaptic (Type III) taste cells (53%) responded to 0.1 μm CGRP with an increase in intracellular Ca(2+). In contrast, Receptor (Type II) taste cells rarely (4%) responded to 0.1 μm CGRP. Using pharmacological tools, the actions of CGRP were probed and elucidated by the CGRP receptor antagonist CGRP(8-37). We demonstrated that this effect of CGRP was dependent on phospholipase C activation and was prevented by the inhibitor U73122. Moreover, applying CGRP caused taste buds to secrete serotonin (5-HT), a Presynaptic (Type III) cell transmitter, but not ATP, a Receptor (Type II) cell transmitter. Further, our previous studies showed that 5-HT released from Presynaptic (Type III) cells provides negative paracrine feedback onto Receptor (Type II) cells by activating 5-HT1A receptors, and reducing ATP secretion. Our data showed that CGRP-evoked 5-HT release reduced taste-evoked ATP secretion. The findings are consistent with a role for CGRP as an inhibitory transmitter that shapes peripheral taste signals via serotonergic signaling during processing gustatory information in taste buds. SIGNIFICANCE STATEMENT The taste sensation is initiated with a highly complex set of interactions between a variety of cells located within the taste buds before signal propagation to the brain. Afferent signals from the oral cavity are carried to the brain in chemosensory fibers that contribute to chemesthesis, the general chemical sensitivity of the mucus membranes in the oronasal cavities and being perceived as pungency, irritation, or heat. This is a study of a fundamental question in neurobiology: how are signals processed in sensory end organs, taste buds? More specifically, taste-modifying interactions, via transmitters, between gustatory and chemosensory afferents inside taste buds will help explain how a coherent output is formed before being transmitted to the brain.
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31
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Marina S, Anna-Lila K, Benjamin M, Raquel L, Komisarczuk AZ, Alejo RS, Adrien J, Alicia L, Nicolas T, Shinji O, Keiko A, Becker TS, Marika K. Diversity in cell motility reveals the dynamic nature of the formation of zebrafish taste sensory organs. Development 2016; 143:2012-24. [DOI: 10.1242/dev.134817] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2016] [Accepted: 04/12/2016] [Indexed: 12/16/2022]
Abstract
Taste buds are sensory organs in jawed vertebrates, composed of distinct cell types that detect and transduce specific taste qualities. Taste bud cells differentiate from oropharyngeal epithelial progenitors localized mainly in proximity of the forming organs. Despite recent progress in elucidating the molecular interactions required for taste bud cell development and function, the cell behaviour underlying the organ assembly is poorly defined. Here, we used time-lapse imaging to observe the formation of taste buds in live zebrafish larvae. We found that tg(fgf8a.dr17) expressing cells form taste buds and get rearranged within the forming organs. In addition, differentiating cells move from the epithelium to the forming organs and can be displaced between developing organs. During organ formation, taste bud tg(fgf8a.dr17) and Type-II cells are displaced in random, directed or confined mode relative to the taste bud they join or are maintained. Finally, ascl1a activity in the 5-HT/Type-III cell is required to direct and maintain tg(fgf8a.dr17) expressing cells into the taste bud. We propose diversity in displacement modes of differentiating cells as a key mechanism for the highly dynamic process of taste bud assembly.
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Affiliation(s)
- Soulika Marina
- IBENS, Ecole Normale Supérieure, CNRS UMR8197, INSERM U1024, Paris, France
| | - Kaushik Anna-Lila
- IBENS, Ecole Normale Supérieure, CNRS UMR8197, INSERM U1024, Paris, France
| | - Mathieu Benjamin
- IBENS, Ecole Normale Supérieure, CNRS UMR8197, INSERM U1024, Paris, France
| | - Lourenço Raquel
- IBENS, Ecole Normale Supérieure, CNRS UMR8197, INSERM U1024, Paris, France
| | - Anna Z. Komisarczuk
- Developmental Neurobiology and Genomics, Brain and Mind Research Institute, University of Sydney, Australia
| | | | - Jouary Adrien
- IBENS, Ecole Normale Supérieure, CNRS UMR8197, INSERM U1024, Paris, France
| | - Lardennois Alicia
- IBENS, Ecole Normale Supérieure, CNRS UMR8197, INSERM U1024, Paris, France
| | - Tissot Nicolas
- Institut Jacques Monod, CNRS UMR7592, University Paris Diderot, Paris, France
| | - Okada Shinji
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Japan
| | - Abe Keiko
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Japan
| | - Thomas S. Becker
- Developmental Neurobiology and Genomics, Brain and Mind Research Institute, University of Sydney, Australia
| | - Kapsimali Marika
- IBENS, Ecole Normale Supérieure, CNRS UMR8197, INSERM U1024, Paris, France
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32
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ATPergic signalling during seizures and epilepsy. Neuropharmacology 2015; 104:140-53. [PMID: 26549853 DOI: 10.1016/j.neuropharm.2015.11.001] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 11/01/2015] [Accepted: 11/02/2015] [Indexed: 10/22/2022]
Abstract
Much progress has been made over the last few decades in the identification of new anti-epileptic drugs (AEDs). However, 30% of epilepsy patients suffer poor seizure control. This underscores the need to identify alternative druggable neurotransmitter systems and drugs with novel mechanisms of action. An emerging concept is that seizure generation involves a complex interplay between neurons and glial cells at the tripartite synapse and neuroinflammation has been proposed as one of the main drivers of epileptogenesis. The ATP-gated purinergic receptor family is expressed throughout the brain and is functional on neurons and glial cells. ATP is released in high amounts into the extracellular space after increased neuronal activity and during chronic inflammation and cell death to act as a neuro- and gliotransmitter. Emerging work shows pharmacological targeting of ATP-gated purinergic P2 receptors can potently modulate seizure generation, inflammatory processes and seizure-induced brain damage. To date, work showing the functional contribution of P2 receptors has been mainly performed in animal models of acute seizures, in particular, by targeting the ionotropic P2X7 receptor subtype. Other ionotropic P2X and metabotropic P2Y receptor family members have also been implicated in pathological processes following seizures such as the P2X4 receptor and the P2Y12 receptor. However, during epilepsy, the characterization of P2 receptors was mostly restricted to the study of expressional changes of the different receptor subtypes. This review summarizes the work to date on ATP-mediated signalling during seizures and the functional impact of targeting the ATP-gated purinergic receptors on seizures and seizure-induced pathology. This article is part of the Special Issue entitled 'Purines in Neurodegeneration and Neuroregeneration'.
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33
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Cherkashin AP, Kolesnikova AS, Tarasov MV, Romanov RA, Rogachevskaja OA, Bystrova MF, Kolesnikov SS. Expression of calcium-activated chloride channels Ano1 and Ano2 in mouse taste cells. Pflugers Arch 2015; 468:305-19. [DOI: 10.1007/s00424-015-1751-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 10/20/2015] [Accepted: 10/23/2015] [Indexed: 02/03/2023]
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Vandenbeuch A, Anderson CB, Kinnamon SC. Mice Lacking Pannexin 1 Release ATP and Respond Normally to All Taste Qualities. Chem Senses 2015; 40:461-7. [PMID: 26136251 DOI: 10.1093/chemse/bjv034] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Adenosine triphosphate (ATP) is required for the transmission of all taste qualities from taste cells to afferent nerve fibers. ATP is released from Type II taste cells by a nonvesicular mechanism and activates purinergic receptors containing P2X2 and P2X3 on nerve fibers. Several ATP release channels are expressed in taste cells including CALHM1, Pannexin 1, Connexin 30, and Connexin 43, but whether all are involved in ATP release is not clear. We have used a global Pannexin 1 knock out (Panx1 KO) mouse in a series of in vitro and in vivo experiments. Our results confirm that Panx1 channels are absent in taste buds of the knockout mice and that other known ATP release channels are not upregulated. Using a luciferin/luciferase assay, we show that circumvallate taste buds from Panx1 KO mice normally release ATP upon taste stimulation compared with wild type (WT) mice. Gustatory nerve recordings in response to various tastants applied to the tongue and brief-access behavioral testing with SC45647 also show no difference between Panx1 KO and WT. These results confirm that Panx1 is not required for the taste evoked release of ATP or for neural and behavioral responses to taste stimuli.
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Affiliation(s)
- Aurelie Vandenbeuch
- Department of Otolaryngology, University of Colorado School of Medicine, Aurora, CO, USA and Rocky Mountain Taste and Smell Center, University of Colorado School of Medicine, Aurora, CO, USA
| | - Catherine B Anderson
- Department of Otolaryngology, University of Colorado School of Medicine, Aurora, CO, USA and Rocky Mountain Taste and Smell Center, University of Colorado School of Medicine, Aurora, CO, USA
| | - Sue C Kinnamon
- Department of Otolaryngology, University of Colorado School of Medicine, Aurora, CO, USA and Rocky Mountain Taste and Smell Center, University of Colorado School of Medicine, Aurora, CO, USA
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35
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King BF. Purinergic signalling in the enteric nervous system (An overview of current perspectives). Auton Neurosci 2015; 191:141-7. [PMID: 26049261 DOI: 10.1016/j.autneu.2015.05.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Purinergic Signalling in the Enteric Nervous System involves the regulated release of ATP (or a structurally-related nucleotide) which activates an extensive suite of membrane-inserted receptors (P2X and P2Y subtypes) on a variety of cell types in the gastrointestinal tract. P2X receptors are gated ion-channels permeable to sodium, potassium and calcium. They depolarise cells, act as a pathway for calcium influx to activate calcium-dependent processes and initiate gene transcription, interact at a molecular level as a form of self-regulation with lipids within the cell wall (e.g. PIP2) and cross-react with other membrane-inserted receptors to regulate their activity (e.g. nAChRs). P2Y receptors are metabotropic receptors that couple to G-proteins. They may release calcium ions from intracellular stores to activate calcium-dependent processes, but also may activate calcium-independent signalling pathways and influence gene transcription. Originally ATP was a candidate only for NANC neurotransmission, for inhibitory motoneurons supplying the muscularis externa of the gastrointestinal tract and bringing about the fast IJP. Purinergic signalling later included neuron-neuron signalling in the ENS, via the production of either fast or slow EPSPs. Later still, purinergic signalling included the neuro-epithelial synapse-for efferent signalling to epithelia cells participating in secretion and absorption, and afferent signalling for chemoreception and mechanoreception at the surface of the mucosa. Many aspects of purinergic signalling have since been addressed in a series of highly-focussed and authoritative reviews. In this overview however, the current focus is on key aspects of purinergic signalling where there remains uncertainty and ambiguity, with the view to stimulating further research in these areas.
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Affiliation(s)
- Brian F King
- University College London (UCL), Department of Neuroscience, Physiology and Pharmacology (NPP), Royal Free Campus, Rowland Hill Street, Hampstead, London NW3 2PF, United Kingdom.
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Vandenbeuch A, Larson ED, Anderson CB, Smith SA, Ford AP, Finger TE, Kinnamon SC. Postsynaptic P2X3-containing receptors in gustatory nerve fibres mediate responses to all taste qualities in mice. J Physiol 2015; 593:1113-25. [PMID: 25524179 DOI: 10.1113/jphysiol.2014.281014] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Accepted: 12/12/2014] [Indexed: 12/15/2022] Open
Abstract
Taste buds release ATP to activate ionotropic purinoceptors composed of P2X2 and P2X3 subunits, present on the taste nerves. Mice with genetic deletion of P2X2 and P2X3 receptors (double knockout mice) lack responses to all taste stimuli presumably due to the absence of ATP-gated receptors on the afferent nerves. Recent experiments on the double knockout mice showed, however, that their taste buds fail to release ATP, suggesting the possibility of pleiotropic deficits in these global knockouts. To test further the role of postsynaptic P2X receptors in afferent signalling, we used AF-353, a selective antagonist of P2X3-containing receptors to inhibit the receptors acutely during taste nerve recording and behaviour. The specificity of AF-353 for P2X3-containing receptors was tested by recording Ca(2+) transients to exogenously applied ATP in fura-2 loaded isolated geniculate ganglion neurons from wild-type and P2X3 knockout mice. ATP responses were completely inhibited by 10 μm or 100 μm AF-353, but neither concentration blocked responses in P2X3 single knockout mice wherein the ganglion cells express only P2X2-containing receptors. Furthermore, AF-353 had no effect on taste-evoked ATP release from taste buds. In wild-type mice, i.p. injection of AF-353 or simple application of the drug directly to the tongue, inhibited taste nerve responses to all taste qualities in a dose-dependent fashion. A brief access behavioural assay confirmed the electrophysiological results and showed that preference for a synthetic sweetener, SC-45647, was abolished following i.p. injection of AF-353. These data indicate that activation of P2X3-containing receptors is required for transmission of all taste qualities.
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Affiliation(s)
- Aurelie Vandenbeuch
- Department of Otolaryngology, University of Colorado School of Medicine, Aurora, CO, USA; Rocky Mountain Taste and Smell Center, University of Colorado School of Medicine, Aurora, CO, USA
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37
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Ye Y, Ono K, Bernabé DG, Viet CT, Pickering V, Dolan JC, Hardt M, Ford AP, Schmidt BL. Adenosine triphosphate drives head and neck cancer pain through P2X2/3 heterotrimers. Acta Neuropathol Commun 2014; 2:62. [PMID: 24903857 PMCID: PMC4229781 DOI: 10.1186/2051-5960-2-62] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2014] [Accepted: 05/20/2014] [Indexed: 11/15/2022] Open
Abstract
Introduction Cancer pain creates a poor quality of life and decreases survival. The basic neurobiology of cancer pain is poorly understood. Adenosine triphosphate (ATP) and the ATP ionotropic receptor subunits, P2X2 and P2X3, mediate cancer pain in animal models; however, it is unknown whether this mechanism operates in human, and if so, what the relative contribution of P2X2- and P2X3-containing trimeric channels to cancer pain is. Here, we studied head and neck squamous cell carcinoma (HNSCC), which causes the highest level of function-induced pain relative to other types of cancer. Results We show that the human HNSCC tissues contain significantly increased levels of ATP compared to the matched normal tissues. The high levels of ATP are secreted by the cancer and positively correlate with self-reported function-induced pain in patients. The human HNSCC microenvironment is densely innervated by nerve fibers expressing both P2X2 and P2X3 subunits. In animal models of HNSCC we showed that ATP in the cancer microenvironment likely heightens pain perception through the P2X2/3 trimeric receptors. Nerve growth factor (NGF), another cancer-derived pain mediator found in both human and mouse HNSCC, induces P2X2 and P2X3 hypersensitivity and increases subunit expression in murine trigeminal ganglion (TG) neurons. Conclusions These data identify a key peripheral mechanism in cancer pain and highlight the clinical potential of specifically targeting nociceptors expressing both P2X2 and P2X3 subunits (e.g., P2X2/3 heterotrimers) to alleviate cancer pain. Electronic supplementary material The online version of this article (doi:10.1186/2051-5960-2-62) contains supplementary material, which is available to authorized users.
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Chaudhari N. Synaptic communication and signal processing among sensory cells in taste buds. J Physiol 2014; 592:3387-92. [PMID: 24665098 DOI: 10.1113/jphysiol.2013.269837] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Taste buds (sensory structures embedded in oral epithelium) show a remarkable diversity of transmitters synthesized and secreted locally. The known transmitters accumulate in a cell type selective manner, with 5-HT and noradrenaline being limited to presynaptic cells, GABA being synthesized in both presynaptic and glial-like cells, and acetylcholine and ATP used for signalling by receptor cells. Each of these transmitters participates in local negative or positive feedback circuits that target particular cell types. Overall, the role of ATP is the best elucidated. ATP serves as a principal afferent transmitter, and also is the key trigger for autocrine positive feedback and paracrine circuits that result in potentiation (via adenosine) or inhibition (via GABA or 5-HT). While many of the cellular receptors and mechanisms for these circuits are known, their impact on sensory detection and perception remains to be elaborated in most instances. This brief review examines what is known, and some of the open questions and controversies surrounding the transmitters and circuits of the taste periphery.
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Affiliation(s)
- Nirupa Chaudhari
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, FL, 33146, USA Program in Neurosciences, Miller School of Medicine, University of Miami, Miami, FL, 33146, USA
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Kinnamon SC, Finger TE. A taste for ATP: neurotransmission in taste buds. Front Cell Neurosci 2013; 7:264. [PMID: 24385952 PMCID: PMC3866518 DOI: 10.3389/fncel.2013.00264] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Accepted: 12/03/2013] [Indexed: 11/13/2022] Open
Abstract
Not only is ATP a ubiquitous source of energy but it is also used widely as an intercellular signal. For example, keratinocytes release ATP in response to numerous external stimuli including pressure, heat, and chemical insult. The released ATP activates purinergic receptors on nerve fibers to generate nociceptive signals. The importance of an ATP signal in epithelial-to-neuronal signaling is nowhere more evident than in the taste system. The receptor cells of taste buds release ATP in response to appropriate stimulation by tastants and the released ATP then activates P2X2 and P2X3 receptors on the taste nerves. Genetic ablation of the relevant P2X receptors leaves an animal without the ability to taste any primary taste quality. Of interest is that release of ATP by taste receptor cells occurs in a non-vesicular fashion, apparently via gated membrane channels. Further, in keeping with the crucial role of ATP as a neurotransmitter in this system, a subset of taste cells expresses a specific ectoATPase, NTPDase2, necessary to clear extracellular ATP which otherwise will desensitize the P2X receptors on the taste nerves. The unique utilization of ATP as a key neurotransmitter in the taste system may reflect the epithelial rather than neuronal origins of the receptor cells.
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Affiliation(s)
- Sue C Kinnamon
- Department of Otolaryngology, Rocky Mountain Taste and Smell Center, University of Colorado School of Medicine Aurora, CO, USA
| | - Thomas E Finger
- Department Cell and Developmental Biology, Rocky Mountain Taste and Smell Center, University of Colorado School of Medicine Aurora, CO, USA
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Miklavc P, Thompson KE, Frick M. A new role for P2X4 receptors as modulators of lung surfactant secretion. Front Cell Neurosci 2013; 7:171. [PMID: 24115920 PMCID: PMC3792447 DOI: 10.3389/fncel.2013.00171] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Accepted: 09/12/2013] [Indexed: 12/17/2022] Open
Abstract
In recent years, P2X receptors have attracted increasing attention as regulators of exocytosis and cellular secretion. In various cell types, P2X receptors have been found to stimulate vesicle exocytosis directly via Ca(2+) influx and elevation of the intracellular Ca(2+) concentration. Recently, a new role for P2X4 receptors as regulators of secretion emerged. Exocytosis of lamellar bodies (LBs), large storage organelles for lung surfactant, results in a local, fusion-activated Ca(2+) entry (FACE) in alveolar type II epithelial cells. FACE is mediated via P2X4 receptors that are located on the limiting membrane of LBs and inserted into the plasma membrane upon exocytosis of LBs. The localized Ca(2+) influx at the site of vesicle fusion promotes fusion pore expansion and facilitates surfactant release. In addition, this inward-rectifying cation current across P2X4 receptors mediates fluid resorption from lung alveoli. It is hypothesized that the concomitant reduction in the alveolar lining fluid facilitates insertion of surfactant into the air-liquid interphase thereby "activating" it. These findings constitute a novel role for P2X4 receptors in regulating vesicle content secretion as modulators of the secretory output during the exocytic post-fusion phase.
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Affiliation(s)
- Pika Miklavc
- Institute of General Physiology, University of Ulm Ulm, Germany
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Taruno A, Matsumoto I, Ma Z, Marambaud P, Foskett JK. How do taste cells lacking synapses mediate neurotransmission? CALHM1, a voltage-gated ATP channel. Bioessays 2013; 35:1111-8. [PMID: 24105910 DOI: 10.1002/bies.201300077] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
CALHM1 was recently demonstrated to be a voltage-gated ATP-permeable ion channel and to serve as a bona fide conduit for ATP release from sweet-, umami-, and bitter-sensing type II taste cells. Calhm1 is expressed in taste buds exclusively in type II cells and its product has structural and functional similarities with connexins and pannexins, two families of channel protein candidates for ATP release by type II cells. Calhm1 knockout in mice leads to loss of perception of sweet, umami, and bitter compounds and to impaired gustatory nerve responses to these tastants. These new studies validate the concept of ATP as the primary neurotransmitter from type II cells to gustatory neurons. Furthermore, they identify voltage-gated ATP release through CALHM1 as an essential molecular mechanism of ATP release in taste buds. We discuss these new findings, as well as unresolved issues in peripheral taste signaling that we hope will stimulate future research.
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Affiliation(s)
- Akiyuki Taruno
- Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine, Kyoto, Japan
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42
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Abstract
Taste buds are unusual in requiring ATP as a transmitter to activate sensory nerve fibers. In response to taste stimuli, taste cells release ATP, activating purinergic receptors containing the P2X2 and P2X3 subunits on taste nerves. In turn, the released ATP is hydrolyzed to ADP by a plasma membrane nucleoside triphosphate previously identified as nucleoside triphosphate diphosphohydrolase-2 (NTPDase2). In this paper we investigate the role of this ectonucleotidase in the function of taste buds by examining gene-targeted Entpd2-null mice globally lacking NTPDase2. RT-PCR confirmed the absence of NTPDase2, and ATPase enzyme histochemistry reveals no reaction product in taste buds of knockout mice, suggesting that NTPDase2 is the dominant form in taste buds. RT-PCR and immunocytochemistry demonstrated that in knockout mice all cell types are present in taste buds, even those cells normally expressing NTPDase2. In addition, the overall number and size of taste buds are normal in Entpd2-null mice. Luciferin/luciferase assays of circumvallate tissue of knockout mice detected elevated levels of extracellular ATP. Electrophysiological recordings from two taste nerves, the chorda tympani and glossopharyngeal, revealed depressed responses to all taste stimuli in Entpd2-null mice. Responses were more depressed in the glossopharyngeal nerve than in the chorda tympani nerve and involved all taste qualities; responses in the chorda tympani were more depressed to sweet and umami stimuli than to other qualities. We suggest that the excessive levels of extracellular ATP in the Entpd2-knockout animals desensitize the P2X receptors associated with nerve fibers, thereby depressing taste responses.
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Cone AC, Ambrosi C, Scemes E, Martone ME, Sosinsky GE. A comparative antibody analysis of pannexin1 expression in four rat brain regions reveals varying subcellular localizations. Front Pharmacol 2013; 4:6. [PMID: 23390418 PMCID: PMC3565217 DOI: 10.3389/fphar.2013.00006] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Accepted: 01/09/2013] [Indexed: 11/13/2022] Open
Abstract
Pannexin1 (Panx1) channels release cytosolic ATP in response to signaling pathways. Panx1 is highly expressed in the central nervous system. We used four antibodies with different Panx1 anti-peptide epitopes to analyze four regions of rat brain. These antibodies labeled the same bands in Western blots and had highly similar patterns of immunofluorescence in tissue culture cells expressing Panx1, but Western blots of brain lysates from Panx1 knockout and control mice showed different banding patterns. Localizations of Panx1 in brain slices were generated using automated wide field mosaic confocal microscopy for imaging large regions of interest while retaining maximum resolution for examining cell populations and compartments. We compared Panx1 expression over the cerebellum, hippocampus with adjacent cortex, thalamus, and olfactory bulb. While Panx1 localizes to the same neuronal cell types, subcellular localizations differ. Two antibodies with epitopes against the intracellular loop and one against the carboxy terminus preferentially labeled cell bodies, while an antibody raised against an N-terminal peptide highlighted neuronal processes more than cell bodies. These labeling patterns may be a reflection of different cellular and subcellular localizations of full-length and/or modified Panx1 channels where each antibody is highlighting unique or differentially accessible Panx1 populations. However, we cannot rule out that one or more of these antibodies have specificity issues. All data associated with experiments from these four antibodies are presented in a manner that allows them to be compared and our claims thoroughly evaluated, rather than eliminating results that were questionable. Each antibody is given a unique identifier through the NIF Antibody Registry that can be used to track usage of individual antibodies across papers and all image and metadata are made available in the public repository, the Cell Centered Database, for on-line viewing, and download.
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Affiliation(s)
- Angela C Cone
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, University of California San Diego, La Jolla, CA, USA
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Abstract
Taste buds are peripheral chemosensory organs situated in the oral cavity. Each taste bud consists of a community of 50-100 cells that interact synaptically during gustatory stimulation. At least three distinct cell types are found in mammalian taste buds - Type I cells, Receptor (Type II) cells, and Presynaptic (Type III) cells. Type I cells appear to be glial-like cells. Receptor cells express G protein-coupled taste receptors for sweet, bitter, or umami compounds. Presynaptic cells transduce acid stimuli (sour taste). Cells that sense salt (NaCl) taste have not yet been confidently identified in terms of these cell types. During gustatory stimulation, taste bud cells secrete synaptic, autocrine, and paracrine transmitters. These transmitters include ATP, acetylcholine (ACh), serotonin (5-HT), norepinephrine (NE), and GABA. Glutamate is an efferent transmitter that stimulates Presynaptic cells to release 5-HT. This chapter discusses these transmitters, which cells release them, the postsynaptic targets for the transmitters, and how cell-cell communication shapes taste bud signaling via these transmitters.
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Affiliation(s)
- Stephen D Roper
- Department of Physiology and Biophysics, and Program in Neuroscience, Miller School of Medicine, University of Miami, 1600 NW 10th Ave., Miami, FL 33136, USA.
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Abstract
Extracellular adenosine 5' triphosphate (ATP) is a widespread cell-to-cell signaling molecule in the brain, where it activates cell surface P2X and P2Y receptors. P2X receptors define a protein family unlike other neurotransmitter-gated ion channels in terms of sequence, subunit topology, assembly, and architecture. Within milliseconds of binding ATP, they catalyze the opening of a cation-selective pore. However, recent data show that P2X receptors often underlie neuromodulatory responses on slower time scales of seconds or longer. Herein, we review these findings at molecular, cellular and systems levels. We propose that, while P2X receptors are fast ligand-gated cation channels, they are most adept at mediating slow neuromodulatory functions that are more widespread and more physiologically utilized than fast ATP synaptic transmission in the CNS.
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Affiliation(s)
- Baljit S Khakh
- Department of Physiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095-1751, USA.
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Romanov RA, Bystrova MF, Rogachevskaya OA, Sadovnikov VB, Shestopalov VI, Kolesnikov SS. The ATP permeability of pannexin 1 channels in a heterologous system and in mammalian taste cells is dispensable. J Cell Sci 2012; 125:5514-23. [PMID: 22956545 DOI: 10.1242/jcs.111062] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Afferent output in type II taste cells is mediated by ATP liberated through ion channels. It is widely accepted that pannexin 1 (Panx1) channels are responsible for ATP release in diverse cell types, including taste cells. While biophysical evidence implicates slow deactivation of ion channels following ATP release in taste cells, recombinant Panx1 activates and deactivates rapidly. This inconsistency could indicate that the cellular context specifies Panx1 functioning. We cloned Panx1 from murine taste tissue, and heterologously expressed it in three different cell lines: HEK-293, CHO and neuroblastoma SK-N-SH cells. In all three cell lines, Panx1 transfection yielded outwardly rectifying anion channels that exhibited fast gating and negligible permeability to anions exceeding 250 Da. Despite expression of Panx1, the host cells did not liberate ATP upon stimulation, making it unclear whether Panx1 is involved in taste-related ATP secretion. This issue was addressed using mice with genetic ablation of the Panx1 gene. The ATP-biosensor assay revealed that, in taste cells devoid of Panx1, ATP secretion was robust and apparently unchanged compared with the control. Our data suggest that Panx1 alone forms a channel that has insufficient permeability to ATP. Perhaps, a distinct subunit and/or a regulatory circuit that is absent in taste cells is required to enable a high ATP-permeability mode of a native Panx1-based channel.
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Affiliation(s)
- Roman A Romanov
- Institute of Cell Biophysics, Russian Academy of Sciences, Institutional Street 3, Pushchino, Moscow Region, 142290, Russia
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A Lys49-PLA2 myotoxin of Bothrops asper triggers a rapid death of macrophages that involves autocrine purinergic receptor signaling. Cell Death Dis 2012; 3:e343. [PMID: 22764102 PMCID: PMC3406575 DOI: 10.1038/cddis.2012.68] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Lys49-PLA(2) myotoxins, an important component of various viperid snake venoms, are a class of PLA(2)-homolog proteins deprived of catalytic activity. Similar to enzymatically active PLA(2) (Asp49) and to other classes of myotoxins, they cause severe myonecrosis. Moreover, these toxins are used as tools to study skeletal muscle repair and regeneration, a process that can be very limited after snakebites. In this work, the cytotoxic effect of different myotoxins, Bothrops asper Lys49 and Asp49-PLA(2), Notechis scutatus notexin and Naja mossambica cardiotoxin, was evaluated on macrophages, cells that have a key role in muscle regeneration. Only the Lys49-myotoxin was found to trigger a rapid asynchronous death of mouse peritoneal macrophages and macrophagic cell lines through a process that involves ATP release, ATP-induced ATP release and that is inhibited by various purinergic receptor antagonists. ATP leakage is induced also at sublytical doses of the Lys49-myotoxin, it involves Ca(2+) release from intracellular stores, and is reduced by inhibitors of VSOR and the maxi-anion channel. The toxin-induced cell death is different from that caused by high concentration of ATP and appears to be linked to localized purinergic signaling. Based on present findings, a mechanism of cell death is proposed that can be extended to other cytolytic proteins and peptides.
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48
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Immunocytochemical analysis of P2X2 in rat circumvallate taste buds. BMC Neurosci 2012; 13:51. [PMID: 22621423 PMCID: PMC3507709 DOI: 10.1186/1471-2202-13-51] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Accepted: 04/20/2012] [Indexed: 11/23/2022] Open
Abstract
Background Our laboratory has shown that classical synapses and synaptic proteins are associated with Type III cells. Yet it is generally accepted that Type II cells transduce bitter, sweet and umami stimuli. No classical synapses, however, have been found associated with Type II cells. Recent studies indicate that the ionotropic purinergic receptors P2X2/P2X3 are present in rodent taste buds. Taste nerve processes express the ionotropic purinergic receptors (P2X2/P2X3). P2X2/P2X3Dbl−/− mice are not responsive to sweet, umami and bitter stimuli, and it has been proposed that ATP acts as a neurotransmitter in taste buds. The goal of the present study is to learn more about the nature of purinergic contacts in rat circumvallate taste buds by examining immunoreactivity to antisera directed against the purinergic receptor P2X2. Results P2X2-like immunoreactivity is present in intragemmal nerve processes in rat circumvallate taste buds. Intense immunoreactivity can also be seen in the subgemmal nerve plexuses located below the basal lamina. The P2X2 immunoreactive nerve processes also display syntaxin-1-LIR. The immunoreactive nerves are in close contact with the IP3R3-LIR Type II cells and syntaxin-1-LIR and/or 5-HT-LIR Type III cells. Taste cell synapses are observed only from Type III taste cells onto P2X2-LIR nerve processes. Unusually large, “atypical” mitochondria in the Type II taste cells are found only at close appositions with P2X2-LIR nerve processes. P2X2 immunogold particles are concentrated at the membranes of nerve processes at close appositions with taste cells. Conclusions Based on our immunofluorescence and immunoelectron microscopical studies we believe that both perigemmal and most all intragemmal nerve processes display P2X2-LIR. Moreover, colloidal gold immunoelectron microscopy indicates that P2X2-LIR in nerve processes is concentrated at sites of close apposition with Type II cells. This supports the hypothesis that ATP may be a key neurotransmitter in taste transduction and that Type II cells release ATP, activating P2X2 receptors in nerve processes.
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Custer EE, Knott TK, Cuadra AE, Ortiz-Miranda S, Lemos JR. P2X purinergic receptor knockout mice reveal endogenous ATP modulation of both vasopressin and oxytocin release from the intact neurohypophysis. J Neuroendocrinol 2012; 24:674-80. [PMID: 22340257 PMCID: PMC3314131 DOI: 10.1111/j.1365-2826.2012.02299.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Bursts of action potentials are crucial for neuropeptide release from the hypothalamic neurohypophysial system (HNS). The biophysical properties of the ion channels involved in the release of these neuropeptides, however, cannot explain the efficacy of such bursting patterns on secretion. We have previously shown that ATP, acting via P2X receptors, potentiates only vasopressin (AVP) release from HNS terminals, whereas its metabolite adenosine, via A1 receptors acting on transient Ca(2+) currents, inhibits both AVP and oxytocin (OT) secretion. Thus, purinergic feedback-mechanisms have been proposed to explain bursting efficacy at HNS terminals. Therefore, in the present study, we have used specific P2X receptor knockout (rKO) mice and purportedly selective P2X receptor antagonists to determine the P2X receptor subtype responsible for endogenous ATP induced potentiation of electrically-stimulated neuropeptide release. Intact neurohypophyses (NH) from wild-type (WT), P2X3 rKO, P2X2/3 rKO and P2X7 rKO mice were electrically stimulated with four 25-s bursts (3 V at 39 Hz) separated by 21-s interburst intervals with or without the P2X2 and P2X3 receptor antagonists, suramin or pyridoxal-phosphate-6-azophenyl-2',4'-disulfonic acid (PPADS). These frequencies, number of bursts, and voltages were determined to maximise both AVP and OT release by electrical stimulations. Treatment of WT mouse NH with suramin/PPADS significantly reduced electrically-stimulated AVP release. A similar inhibition by suramin was observed in electrically-stimulated NH from P2X3 and P2X7 rKO mice but not P2X2/3 rKO mice, indicating that endogenous ATP facilitation of electrically-stimulated AVP release is mediated primarily by the activation of the P2X2 receptor. Unexpectedly, electrically-stimulated OT release from WT, P2X3, P2X2/3 and P2X7 rKO mice was potentiated by suramin, indicating nonpurinergic effects by this 'selective' antagonist. Nevertheless, these results show that sufficient endogenous ATP is released by bursts of action potentials to act at P2X2 receptors in a positive-feedback mechanism to 'differentially' modulate neuropeptide release from central nervous system terminals.
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MESH Headings
- Action Potentials/drug effects
- Action Potentials/physiology
- Adenosine Triphosphate/physiology
- Animals
- Arginine Vasopressin/metabolism
- Electric Stimulation/methods
- In Vitro Techniques
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Models, Biological
- Oxytocin/metabolism
- Pituitary Gland, Posterior/drug effects
- Pituitary Gland, Posterior/metabolism
- Purinergic P2X Receptor Antagonists/pharmacology
- Pyridoxal Phosphate/analogs & derivatives
- Pyridoxal Phosphate/pharmacology
- Rats
- Rats, Sprague-Dawley
- Receptors, Purinergic P2X2/genetics
- Receptors, Purinergic P2X2/physiology
- Receptors, Purinergic P2X3/genetics
- Receptors, Purinergic P2X3/physiology
- Suramin/pharmacology
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Affiliation(s)
| | | | | | | | - José R. Lemos
- To whom all correspondence should be addressed: ; (508)856-8567 fax: (508)856-5997
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Huang YA, Grant J, Roper S. Glutamate may be an efferent transmitter that elicits inhibition in mouse taste buds. PLoS One 2012; 7:e30662. [PMID: 22292013 PMCID: PMC3266908 DOI: 10.1371/journal.pone.0030662] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2011] [Accepted: 12/22/2011] [Indexed: 11/19/2022] Open
Abstract
Recent studies suggest that l-glutamate may be an efferent transmitter released from axons innervating taste buds. In this report, we determined the types of ionotropic synaptic glutamate receptors present on taste cells and that underlie this postulated efferent transmission. We also studied what effect glutamate exerts on taste bud function. We isolated mouse taste buds and taste cells, conducted functional imaging using Fura 2, and used cellular biosensors to monitor taste-evoked transmitter release. The findings show that a large fraction of Presynaptic (Type III) taste bud cells (∼50%) respond to 100 µM glutamate, NMDA, or kainic acid (KA) with an increase in intracellular Ca(2+). In contrast, Receptor (Type II) taste cells rarely (4%) responded to 100 µM glutamate. At this concentration and with these compounds, these agonists activate glutamatergic synaptic receptors, not glutamate taste (umami) receptors. Moreover, applying glutamate, NMDA, or KA caused taste buds to secrete 5-HT, a Presynaptic taste cell transmitter, but not ATP, a Receptor cell transmitter. Indeed, glutamate-evoked 5-HT release inhibited taste-evoked ATP secretion. The findings are consistent with a role for glutamate in taste buds as an inhibitory efferent transmitter that acts via ionotropic synaptic glutamate receptors.
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MESH Headings
- Animals
- CHO Cells
- Cricetinae
- Cricetulus
- Glutamic Acid/metabolism
- Glutamic Acid/pharmacology
- Green Fluorescent Proteins/genetics
- Green Fluorescent Proteins/metabolism
- Mice
- Mice, Inbred C57BL
- Mice, Transgenic
- Neural Inhibition/drug effects
- Neural Inhibition/genetics
- Neural Inhibition/physiology
- Neurons, Efferent/drug effects
- Neurons, Efferent/metabolism
- Neurons, Efferent/physiology
- Neurotransmitter Agents/metabolism
- Neurotransmitter Agents/pharmacology
- Phospholipase C beta/genetics
- Receptor, Serotonin, 5-HT2C/genetics
- Receptor, Serotonin, 5-HT2C/metabolism
- Receptors, Purinergic P2X2/genetics
- Receptors, Purinergic P2X2/metabolism
- Receptors, Purinergic P2X3/genetics
- Receptors, Purinergic P2X3/metabolism
- Synaptic Transmission/drug effects
- Synaptic Transmission/genetics
- Taste Buds/drug effects
- Taste Buds/metabolism
- Taste Buds/physiology
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Affiliation(s)
- Yijen A Huang
- Department of Physiology and Biophysics, University of Miami School of Medicine, Miami, Florida, United States of America.
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