51
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Abstract
Ramsey and DeSimone highlight the recent discovery of a new family of proton channels.
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Affiliation(s)
- I Scott Ramsey
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, VA
| | - John A DeSimone
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, VA
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52
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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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53
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Tu YH, Cooper AJ, Teng B, Chang RB, Artiga DJ, Turner HN, Mulhall EM, Ye W, Smith AD, Liman ER. An evolutionarily conserved gene family encodes proton-selective ion channels. Science 2018; 359:1047-1050. [PMID: 29371428 DOI: 10.1126/science.aao3264] [Citation(s) in RCA: 155] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 01/08/2018] [Indexed: 12/20/2022]
Abstract
Ion channels form the basis for cellular electrical signaling. Despite the scores of genetically identified ion channels selective for other monatomic ions, only one type of proton-selective ion channel has been found in eukaryotic cells. By comparative transcriptome analysis of mouse taste receptor cells, we identified Otopetrin1 (OTOP1), a protein required for development of gravity-sensing otoconia in the vestibular system, as forming a proton-selective ion channel. We found that murine OTOP1 is enriched in acid-detecting taste receptor cells and is required for their zinc-sensitive proton conductance. Two related murine genes, Otop2 and Otop3, and a Drosophila ortholog also encode proton channels. Evolutionary conservation of the gene family and its widespread tissue distribution suggest a broad role for proton channels in physiology and pathophysiology.
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Affiliation(s)
- Yu-Hsiang Tu
- Department of Biological Sciences, Section of Neurobiology, University of Southern California, Los Angeles, CA 90089, USA
| | - Alexander J Cooper
- Department of Biological Sciences, Section of Neurobiology, University of Southern California, Los Angeles, CA 90089, USA
| | - Bochuan Teng
- Department of Biological Sciences, Section of Neurobiology, University of Southern California, Los Angeles, CA 90089, USA
| | - Rui B Chang
- Department of Biological Sciences, Section of Neurobiology, University of Southern California, Los Angeles, CA 90089, USA
| | - Daniel J Artiga
- Department of Biological Sciences, Section of Neurobiology, University of Southern California, Los Angeles, CA 90089, USA
| | - Heather N Turner
- Department of Biological Sciences, Section of Neurobiology, University of Southern California, Los Angeles, CA 90089, USA
| | - Eric M Mulhall
- Department of Biological Sciences, Section of Neurobiology, University of Southern California, Los Angeles, CA 90089, USA
| | - Wenlei Ye
- Department of Biological Sciences, Section of Neurobiology, University of Southern California, Los Angeles, CA 90089, USA.
| | - Andrew D Smith
- Department of Biological Sciences, Section of Molecular and Computational Biology, University of Southern California, Los Angeles, CA 90089, USA
| | - Emily R Liman
- Department of Biological Sciences, Section of Neurobiology, University of Southern California, Los Angeles, CA 90089, USA. .,Bridge Institute, University of Southern California, Los Angeles, CA 90089, USA
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54
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Matsugasumi M, Hashimoto Y, Okada H, Tanaka M, Kimura T, Kitagawa N, Tanaka Y, Fukuda Y, Sakai R, Yamazaki M, Oda Y, Nakamura N, Fukui M. The Association Between Taste Impairment and Serum Zinc Concentration in Adult Patients With Type 2 Diabetes. Can J Diabetes 2018; 42:520-524. [PMID: 29551654 DOI: 10.1016/j.jcjd.2018.01.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Accepted: 01/03/2018] [Indexed: 12/01/2022]
Abstract
OBJECTIVES In this study, we aimed to elucidate the association between taste acuity and serum zinc concentration in patients with type 2 diabetes. METHODS We enrolled 29 patients who were hospitalized and asked them to attend a 2-week diabetes education program. Fasting blood samples were obtained on the morning of the first day and 2 weeks after hospitalization. The acuity of sweet, salty, sour or bitter taste was evaluated by a filter-paper disc method. Correlations among taste acuity, glycemic control and serum zinc concentration were analyzed using the Spearman rank correlation coefficient. RESULTS The following parameters (mean ± standard deviation) were improved after 2 weeks' hospitalization: taste acuity (sweet: 3.5±1.0 to 2.9±1.1; salty: 3.3±1.1 to 2.6±1.0; sour: 3.6±1.2 to 2.7±0.8; and bitter: 3.3±1.3 to 2.7±1.1; all p<0.001); glycemic control (fasting plasma glucose, 9.4±3.0 to 7.1±1.8 mmol/L, and glycoalbumin, 26.3±7.7 to 22.7±5.9 %; both p<0.001); and serum zinc concentration (1.2±0.2 to 1.3±0.2 mmol/L; p<0.001). Sour and bitter taste acuity were significantly associated with serum zinc concentration (sour, r=-0.50, p=0.005; bitter, r=-0.40, p=0.033). CONCLUSIONS Glycemic control, serum zinc concentration and taste acuity were improved after the short-duration education program. Sour and bitter taste acuity were significantly associated with serum zinc concentrations.
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Affiliation(s)
- Masako Matsugasumi
- Department of Endocrinology and Metabolism, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, Kyoto, Japan
| | - Yoshitaka Hashimoto
- Department of Endocrinology and Metabolism, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, Kyoto, Japan
| | - Hiroshi Okada
- Department of Internal Medicine, Matsushita Memorial Hospital, Moriguchi, Japan
| | - Muhei Tanaka
- Department of Endocrinology and Metabolism, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, Kyoto, Japan
| | - Toshihiro Kimura
- Department of Endocrinology and Metabolism, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, Kyoto, Japan
| | - Noriyuki Kitagawa
- Department of Endocrinology and Metabolism, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, Kyoto, Japan
| | - Yoshimitsu Tanaka
- Department of Endocrinology and Metabolism, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, Kyoto, Japan
| | - Yukiko Fukuda
- Department of Endocrinology and Metabolism, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, Kyoto, Japan
| | - Ryousuke Sakai
- Department of Endocrinology and Metabolism, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, Kyoto, Japan
| | - Masahiro Yamazaki
- Department of Endocrinology and Metabolism, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, Kyoto, Japan
| | - Yohei Oda
- Department of Endocrinology and Metabolism, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, Kyoto, Japan
| | - Naoto Nakamura
- Department of Endocrinology and Metabolism, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, Kyoto, Japan
| | - Michiaki Fukui
- Department of Endocrinology and Metabolism, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, Kyoto, Japan.
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55
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Wilson CE, Finger TE, Kinnamon SC. Type III Cells in Anterior Taste Fields Are More Immunohistochemically Diverse Than Those of Posterior Taste Fields in Mice. Chem Senses 2017; 42:759-767. [PMID: 28968659 DOI: 10.1093/chemse/bjx055] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Activation of Type III cells in mammalian taste buds is implicated in the transduction of acids (sour) and salty stimuli. Several lines of evidence suggest that function of Type III cells in the anterior taste fields may differ from that of Type III cells in posterior taste fields. Underlying anatomy to support this observation is, however, scant. Most existing immunohistochemical data characterizing this cell type focus on circumvallate taste buds in the posterior tongue. Equivalent data from anterior taste fields-fungiform papillae and soft palate-are lacking. Here, we compare Type III cells in four taste fields: fungiform, soft palate, circumvallate, and foliate in terms of reactivity to four canonical markers of Type III cells: polycystic kidney disease 2-like 1 (PKD2L1), synaptosomal associated protein 25 (SNAP25), serotonin (5-HT), and glutamate decarboxylase 67 (GAD67). Our findings indicate that while PKD2L1, 5-HT, and SNAP25 are highly coincident in posterior taste fields, they diverge in anterior taste fields. In particular, a subset of taste cells expresses PKD2L1 without the synaptic markers, and a subset of SNAP25 cells lacks expression of PKD2L1. In posterior taste fields, GAD67-positive cells are a subset of PKD2L1 expressing taste cells, but anterior taste fields also contain a significant population of GAD67-only expressing cells. These differences in expression patterns may underlie the observed functional differences between anterior and posterior taste fields.
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Affiliation(s)
- Courtney E Wilson
- Rocky Mountain Taste and Smell Center, University of Colorado School of Medicine, Aurora, CO 80045, USA.,Department of Otolaryngology, University of Colorado School of Medicine, Aurora, CO 80045, USA.,Neuroscience Graduate Program, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Thomas E Finger
- Rocky Mountain Taste and Smell Center, University of Colorado School of Medicine, Aurora, CO 80045, USA.,Neuroscience Graduate Program, University of Colorado School of Medicine, Aurora, CO 80045, USA.,Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Sue C Kinnamon
- Rocky Mountain Taste and Smell Center, University of Colorado School of Medicine, Aurora, CO 80045, USA.,Department of Otolaryngology, University of Colorado School of Medicine, Aurora, CO 80045, USA.,Neuroscience Graduate Program, University of Colorado School of Medicine, Aurora, CO 80045, USA
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56
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Fuster C, Perrot J, Berthier C, Jacquemond V, Allard B. Elevated resting H + current in the R1239H type 1 hypokalaemic periodic paralysis mutated Ca 2+ channel. J Physiol 2017; 595:6417-6428. [PMID: 28857175 DOI: 10.1113/jp274638] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 08/28/2017] [Indexed: 12/19/2022] Open
Abstract
KEY POINTS Missense mutations in the gene encoding the α1 subunit of the skeletal muscle voltage-gated Ca2+ channel induce type 1 hypokalaemic periodic paralysis, a poorly understood neuromuscular disease characterized by episodic attacks of paralysis associated with low serum K+ . Acute expression of human wild-type and R1239H HypoPP1 mutant α1 subunits in mature mouse muscles showed that R1239H fibres displayed Ca2+ currents of reduced amplitude and larger resting leak inward current increased by external acidification. External acidification also produced intracellular acidification at a higher rate in R1239H fibres and inhibited inward rectifier K+ currents. These data suggest that the R1239H mutation induces an elevated leak H+ current at rest flowing through a gating pore and could explain why paralytic attacks preferentially occur during the recovery period following muscle exercise. ABSTRACT Missense mutations in the gene encoding the α1 subunit of the skeletal muscle voltage-gated Ca2+ channel induce type 1 hypokalaemic periodic paralysis, a poorly understood neuromuscular disease characterized by episodic attacks of paralysis associated with low serum K+ . The present study aimed at identifying the changes in muscle fibre electrical properties induced by acute expression of the R1239H hypokalaemic periodic paralysis human mutant α1 subunit of Ca2+ channels in a mature muscle environment to better understand the pathophysiological mechanisms involved in this disorder. We transferred genes encoding wild-type and R1239H mutant human Ca2+ channels into hindlimb mouse muscle by electroporation and combined voltage-clamp and intracellular pH measurements on enzymatically dissociated single muscle fibres. As compared to fibres expressing wild-type α1 subunits, R1239H mutant-expressing fibres displayed Ca2+ currents of reduced amplitude and a higher resting leak inward current that was increased by external acidification. External acidification also produced intracellular acidification at a higher rate in R1239H fibres and inhibited inward rectifier K+ currents. These data indicate that the R1239H mutation induces an elevated leak H+ current at rest flowing through a gating pore created by the mutation and that external acidification favours onset of muscle paralysis by potentiating H+ depolarizing currents and inhibiting resting inward rectifier K+ currents. Our results could thus explain why paralytic attacks preferentially occur during the recovery period following intense muscle exercise.
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Affiliation(s)
- Clarisse Fuster
- Institut NeuroMyoGene, Université Lyon 1, Université de Lyon, UMR CNRS 5310, Inserm U1217, 43 bd du 11 Novembre 1918, 69622, Villeurbanne, France
| | - Jimmy Perrot
- Institut NeuroMyoGene, Université Lyon 1, Université de Lyon, UMR CNRS 5310, Inserm U1217, 43 bd du 11 Novembre 1918, 69622, Villeurbanne, France
| | - Christine Berthier
- Institut NeuroMyoGene, Université Lyon 1, Université de Lyon, UMR CNRS 5310, Inserm U1217, 43 bd du 11 Novembre 1918, 69622, Villeurbanne, France
| | - Vincent Jacquemond
- Institut NeuroMyoGene, Université Lyon 1, Université de Lyon, UMR CNRS 5310, Inserm U1217, 43 bd du 11 Novembre 1918, 69622, Villeurbanne, France
| | - Bruno Allard
- Institut NeuroMyoGene, Université Lyon 1, Université de Lyon, UMR CNRS 5310, Inserm U1217, 43 bd du 11 Novembre 1918, 69622, Villeurbanne, France
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57
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Chen Y, Amrein H. Ionotropic Receptors Mediate Drosophila Oviposition Preference through Sour Gustatory Receptor Neurons. Curr Biol 2017; 27:2741-2750.e4. [PMID: 28889974 DOI: 10.1016/j.cub.2017.08.003] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Revised: 06/29/2017] [Accepted: 08/01/2017] [Indexed: 01/05/2023]
Abstract
Carboxylic acids are present in many foods, being especially abundant in fruits. Yet, relatively little is known about how acids are detected by gustatory systems and whether they have a potential role in nutrition or provide other health benefits. Here we identify sour gustatory receptor neurons (GRNs) in tarsal taste sensilla of Drosophila melanogaster. We find that most tarsal sensilla harbor a sour GRN that is specifically activated by carboxylic and mineral acids but does not respond to sweet- and bitter-tasting chemicals or salt. One pair of taste sensilla features two GRNs that respond only to a subset of carboxylic acids and high concentrations of salt. All sour GRNs prominently express two Ionotropic Receptor (IR) genes, IR76b and IR25a, and we show that both these genes are necessary for the detection of acids. Furthermore, we establish that IR25a and IR76b are essential in sour GRNs of females for oviposition preference on acid-containing food. Our investigations reveal that acids activate a unique set of taste cells largely dedicated to sour taste, and they indicate that both pH/proton concentration and the structure of carboxylic acids contribute to sour GRN activation. Together, our studies provide new insights into the cellular and molecular basis of sour taste.
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Affiliation(s)
- Yan Chen
- Department of Molecular and Cellular Medicine, College of Medicine, Texas A&M University Health Science Center, College Station, TX 77843, USA
| | - Hubert Amrein
- Department of Molecular and Cellular Medicine, College of Medicine, Texas A&M University Health Science Center, College Station, TX 77843, USA.
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58
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Sukumaran SK, Lewandowski BC, Qin Y, Kotha R, Bachmanov AA, Margolskee RF. Whole transcriptome profiling of taste bud cells. Sci Rep 2017; 7:7595. [PMID: 28790351 PMCID: PMC5548921 DOI: 10.1038/s41598-017-07746-z] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Accepted: 07/03/2017] [Indexed: 12/15/2022] Open
Abstract
Analysis of single-cell RNA-Seq data can provide insights into the specific functions of individual cell types that compose complex tissues. Here, we examined gene expression in two distinct subpopulations of mouse taste cells: Tas1r3-expressing type II cells and physiologically identified type III cells. Our RNA-Seq libraries met high quality control standards and accurately captured differential expression of marker genes for type II (e.g. the Tas1r genes, Plcb2, Trpm5) and type III (e.g. Pkd2l1, Ncam, Snap25) taste cells. Bioinformatics analysis showed that genes regulating responses to stimuli were up-regulated in type II cells, while pathways related to neuronal function were up-regulated in type III cells. We also identified highly expressed genes and pathways associated with chemotaxis and axon guidance, providing new insights into the mechanisms underlying integration of new taste cells into the taste bud. We validated our results by immunohistochemically confirming expression of selected genes encoding synaptic (Cplx2 and Pclo) and semaphorin signalling pathway (Crmp2, PlexinB1, Fes and Sema4a) components. The approach described here could provide a comprehensive map of gene expression for all taste cell subpopulations and will be particularly relevant for cell types in taste buds and other tissues that can be identified only by physiological methods.
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Affiliation(s)
- Sunil K Sukumaran
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA, 19104, USA
| | - Brian C Lewandowski
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA, 19104, USA
| | - Yumei Qin
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA, 19104, USA.,College of Food & Biology Engineering, Zhejiang Gongshang University, Hangzhou, 310018, P.R. China
| | - Ramana Kotha
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA, 19104, USA
| | | | - Robert F Margolskee
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA, 19104, USA.
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59
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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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60
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The cellular mechanism for water detection in the mammalian taste system. Nat Neurosci 2017; 20:927-933. [DOI: 10.1038/nn.4575] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 04/30/2017] [Indexed: 12/20/2022]
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61
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Stratford JM, Larson ED, Yang R, Salcedo E, Finger TE. 5-HT 3A -driven green fluorescent protein delineates gustatory fibers innervating sour-responsive taste cells: A labeled line for sour taste? J Comp Neurol 2017; 525:2358-2375. [PMID: 28316078 DOI: 10.1002/cne.24209] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Revised: 03/03/2017] [Accepted: 03/10/2017] [Indexed: 12/29/2022]
Abstract
Taste buds contain multiple cell types with each type expressing receptors and transduction components for a subset of taste qualities. The sour sensing cells, Type III cells, release serotonin (5-HT) in response to the presence of sour (acidic) tastants and this released 5-HT activates 5-HT3 receptors on the gustatory nerves. We show here, using 5-HT3A GFP mice, that 5-HT3 -expressing nerve fibers preferentially contact and receive synaptic contact from Type III taste cells. Further, these 5-HT3 -expressing nerve fibers terminate in a restricted central-lateral portion of the nucleus of the solitary tract (nTS)-the same area that shows increased c-Fos expression upon presentation of a sour tastant (30 mM citric acid). This acid stimulation also evokes c-Fos in the laterally adjacent mediodorsal spinal trigeminal nucleus (DMSp5), but this trigeminal activation is not associated with the presence of 5-HT3 -expressing nerve fibers as it is in the nTS. Rather, the neuronal activation in the trigeminal complex likely is attributable to direct depolarization of acid-sensitive trigeminal nerve fibers, for example, polymodal nociceptors, rather than through taste buds. Taken together, these findings suggest that transmission of sour taste information involves communication between Type III taste cells and 5-HT3 -expressing afferent nerve fibers that project to a restricted portion of the nTS consistent with a crude mapping of taste quality information in the primary gustatory nucleus.
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Affiliation(s)
- J M Stratford
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, Colorado.,Rocky Mountain Taste and Smell Center, University of Colorado School of Medicine, Aurora, Colorado
| | - E D Larson
- Rocky Mountain Taste and Smell Center, University of Colorado School of Medicine, Aurora, Colorado.,Department of Otolaryngology, University of Colorado School of Medicine, Aurora, Colorado
| | - R Yang
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, Colorado.,Rocky Mountain Taste and Smell Center, University of Colorado School of Medicine, Aurora, Colorado
| | - E Salcedo
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, Colorado.,Rocky Mountain Taste and Smell Center, University of Colorado School of Medicine, Aurora, Colorado
| | - T E Finger
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, Colorado.,Rocky Mountain Taste and Smell Center, University of Colorado School of Medicine, Aurora, Colorado
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62
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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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63
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Ma Z, Saung WT, Foskett JK. Action potentials and ion conductances in wild-type and CALHM1-knockout type II taste cells. J Neurophysiol 2017; 117:1865-1876. [PMID: 28202574 DOI: 10.1152/jn.00835.2016] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Revised: 02/09/2017] [Accepted: 02/09/2017] [Indexed: 11/22/2022] Open
Abstract
Taste bud type II cells fire action potentials in response to tastants, triggering nonvesicular ATP release to gustatory neurons via voltage-gated CALHM1-associated ion channels. Whereas CALHM1 regulates mouse cortical neuron excitability, its roles in regulating type II cell excitability are unknown. In this study, we compared membrane conductances and action potentials in single identified TRPM5-GFP-expressing circumvallate papillae type II cells acutely isolated from wild-type (WT) and Calhm1 knockout (KO) mice. The activation kinetics of large voltage-gated outward currents were accelerated in cells from Calhm1 KO mice, and their associated nonselective tail currents, previously shown to be highly correlated with ATP release, were completely absent in Calhm1 KO cells, suggesting that CALHM1 contributes to all of these currents. Calhm1 deletion did not significantly alter resting membrane potential or input resistance, the amplitudes and kinetics of Na+ currents either estimated from action potentials or recorded from steady-state voltage pulses, or action potential threshold, overshoot peak, afterhyperpolarization, and firing frequency. However, Calhm1 deletion reduced the half-widths of action potentials and accelerated the deactivation kinetics of transient outward currents, suggesting that the CALHM1-associated conductance becomes activated during the repolarization phase of action potentials.NEW & NOTEWORTHY CALHM1 is an essential ion channel component of the ATP neurotransmitter release mechanism in type II taste bud cells. Its contribution to type II cell resting membrane properties and excitability is unknown. Nonselective voltage-gated currents, previously associated with ATP release, were absent in cells lacking CALHM1. Calhm1 deletion was without effects on resting membrane properties or voltage-gated Na+ and K+ channels but contributed modestly to the kinetics of action potentials.
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Affiliation(s)
- Zhongming Ma
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; and
| | - Wint Thu Saung
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; and
| | - J Kevin Foskett
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; and.,Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
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64
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Zhang W, Chen P, Zhou L, Qin Z, Gao K, Yao J, Li C, Wang P. A biomimetic bioelectronic tongue: A switch for On- and Off- response of acid sensations. Biosens Bioelectron 2016; 92:523-528. [PMID: 27836602 DOI: 10.1016/j.bios.2016.10.069] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 10/24/2016] [Accepted: 10/25/2016] [Indexed: 11/24/2022]
Abstract
The perception of sour taste in mammals is important for its basic modality properties and avoiding toxic substances. We explore a biomimetic bioelectronic tongue, which integrate MEA (microelectrode array) and taste receptor cell for acid detection as a switch. However, the acid-sensing mechanism and coding of the taste receptor cells in the periphery is not well understood, with long-standing debate. Therefore, we firstly construct a Hodgkin-Huxley type mathematical model of whole-cell acid-sensing taste receptor cells based on the electrophysiologic patch clamp recordings with different acid sensitive receptor expressing and different acidic stimulations. ASICs and PKDL channels are two most promising candidates for acidic sensation. ASICs channels contribute to the On response, and PKDL channels coding the Offset stimulations respectively, which function as a pair for switch. Therefore, with the advantage of effective and noninvasive detection for MEA, a sour taste biosensor based on MEA and taste receptor cells was designed and established to detect sour response from the elementary acid sensitive taste receptor cells during and after stimulus. From simulation and extracelluar potential recordings, we found the biomimetic bioelectronic tongue was acid-sensitive, as acid stimulation pH decrease, the firing frequency significantly increase. Furthermore, this reliable and effective MEA based bioelectronic tongue functioned as a switch for stimulation On and Off. This study provided a powerful platform to recognize sour stimulation and help elucidate the sour taste sensation and coding mechanism.
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Affiliation(s)
- Wei Zhang
- CAS key Laboratory of Bio-medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou 215163, China.
| | - Peihua Chen
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
| | - Lianqun Zhou
- CAS key Laboratory of Bio-medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou 215163, China
| | - Zhen Qin
- Biosensor National Special Laboratory, Key Laboratory for Biomedical Engineering, Ministry of Education, Department of Biomedical Engineering, Zhejiang University, Hangzhou 310027, China
| | - Keqiang Gao
- Biosensor National Special Laboratory, Key Laboratory for Biomedical Engineering, Ministry of Education, Department of Biomedical Engineering, Zhejiang University, Hangzhou 310027, China
| | - Jia Yao
- CAS key Laboratory of Bio-medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou 215163, China
| | - Chuanyu Li
- CAS key Laboratory of Bio-medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou 215163, China
| | - Ping Wang
- Biosensor National Special Laboratory, Key Laboratory for Biomedical Engineering, Ministry of Education, Department of Biomedical Engineering, Zhejiang University, Hangzhou 310027, China.
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Taruno A, Kashio M, Sun H, Kobayashi K, Sano H, Nambu A, Marunaka Y. Adeno-Associated Virus-Mediated Gene Transfer into Taste Cells In Vivo. Chem Senses 2016; 42:69-78. [PMID: 27940927 DOI: 10.1093/chemse/bjw101] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The sense of taste is achieved by cooperation of many signaling molecules expressed in taste cells, which code and transmit information on quality and intensity of taste to the nervous system. Viral vector-mediated gene transfer techniques have been proven to be useful to study and control function of a gene product in vivo However, there is no transduction method for taste cells in live animals. Here, we have established a method for inducing foreign gene expression in mouse taste cells in vivo by recombinant adeno-associated virus (AAV) vector. First, using enhanced green fluorescent protein (EGFP) as a reporter, we screened 6 AAV serotypes along with a recombinant lentivirus vector for their ability to transduce taste cells. One week after viral injection into the submucosa of the tongue, EGFP expression in fungiform taste cells was observed only in animals injected with AAV-DJ, a synthetic serotype. Next, time course of AAV-DJ-mediated EGFP expression in fungiform taste cells was evaluated. Intragemmal EGFP signals appeared after a delay, rapidly increased until 7 days postinjection, and gradually decreased over the next few weeks probably because of the cell turnover. Finally, the taste cell types susceptible to AAV-DJ transduction were characterized. EGFP expression was observed in PLCβ2-immunoreactive type II and aromatic l-amino acid decarboxylase (AADC)-immunoreactive type III taste cells as well as in cells immunonegative for both PLCβ2 and AADC, demonstrating that AAV-DJ does not discriminate functional taste cell types. In conclusion, the method established in this study will be a promising tool to study the mechanism of taste.
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Affiliation(s)
- Akiyuki Taruno
- Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan
| | - Makiko Kashio
- Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan
| | - Hongxin Sun
- Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan
| | - Kenta Kobayashi
- Section of Viral Vector Development, National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki 444-8585, Japan.,Department of Physiological Sciences, SOKENDAI (The Graduate University for Advanced Studies), Okazaki 444-8585, Japan
| | - Hiromi Sano
- Department of Physiological Sciences, SOKENDAI (The Graduate University for Advanced Studies), Okazaki 444-8585, Japan.,Division of System Neurophysiology, National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki 444-8585, Japan and
| | - Atsushi Nambu
- Section of Viral Vector Development, National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki 444-8585, Japan.,Department of Physiological Sciences, SOKENDAI (The Graduate University for Advanced Studies), Okazaki 444-8585, Japan.,Division of System Neurophysiology, National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki 444-8585, Japan and
| | - Yoshinori Marunaka
- Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.,Department of Bio-Ionomics, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan
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66
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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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Abstract
The taste system of animals is used to detect valuable nutrients and harmful compounds in foods. In humans and mice, sweet, bitter, salty, sour and umami tastes are considered the five basic taste qualities. Sweet and umami tastes are mediated by G-protein-coupled receptors, belonging to the T1R (taste receptor type 1) family. This family consists of three members (T1R1, T1R2 and T1R3). They function as sweet or umami taste receptors by forming heterodimeric complexes, T1R1+T1R3 (umami) or T1R2+T1R3 (sweet). Receptors for each of the basic tastes are thought to be expressed exclusively in taste bud cells. Sweet (T1R2+T1R3-expressing) taste cells were thought to be segregated from umami (T1R1+T1R3-expressing) taste cells in taste buds. However, recent studies have revealed that a significant portion of taste cells in mice expressed all T1R subunits and responded to both sweet and umami compounds. This suggests that sweet and umami taste cells may not be segregated. Mice are able to discriminate between sweet and umami tastes, and both tastes contribute to behavioural preferences for sweet or umami compounds. There is growing evidence that T1R3 is also involved in behavioural avoidance of calcium tastes in mice, which implies that there may be a further population of T1R-expressing taste cells that mediate aversion to calcium taste. Therefore the simple view of detection and segregation of sweet and umami tastes by T1R-expressing taste cells, in mice, is now open to re-examination.
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68
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Wu C, Lillehoj PB, Wang P. Bioanalytical and chemical sensors using living taste, olfactory, and neural cells and tissues: a short review. Analyst 2016; 140:7048-61. [PMID: 26308143 DOI: 10.1039/c5an01288k] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Biosensors utilizing living tissues and cells have recently gained significant attention as functional devices for chemical sensing and biochemical analysis. These devices integrate biological components (i.e. single cells, cell networks, tissues) with micro-electro-mechanical systems (MEMS)-based sensors and transducers. Various types of cells and tissues derived from natural and bioengineered sources have been used as recognition and sensing elements, which are generally characterized by high sensitivity and specificity. This review summarizes the state of the art in tissue- and cell-based biosensing platforms with an emphasis on those using taste, olfactory, and neural cells and tissues. Many of these devices employ unique integration strategies and sensing schemes based on sensitive transducers including microelectrode arrays (MEAs), field effect transistors (FETs), and light-addressable potentiometric sensors (LAPSs). Several groups have coupled these hybrid biosensors with microfluidics which offers added benefits of small sample volumes and enhanced automation. While this technology is currently limited to lab settings due to the limited stability of living biological components, further research to enhance their robustness will enable these devices to be employed in field and clinical settings.
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Affiliation(s)
- Chunsheng Wu
- Biosensor National Special Laboratory, Key Laboratory for Biomedical Engineering of Ministry of Education, Department of Biomedical Engineering, Zhejiang University, Hangzhou 310027, China.
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69
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Aleman MG, Marconi LJ, Nguyen NH, Park JM, Patino MM, Wang Y, Watkins CS, Shelley C. The Influence of Assay Design, Blinding, and Gymnema sylvestre on Sucrose Detection by Humans. JOURNAL OF UNDERGRADUATE NEUROSCIENCE EDUCATION : JUNE : A PUBLICATION OF FUN, FACULTY FOR UNDERGRADUATE NEUROSCIENCE 2016; 15:A18-A23. [PMID: 27980466 PMCID: PMC5105959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 08/04/2016] [Accepted: 08/08/2016] [Indexed: 06/06/2023]
Abstract
The detection and grading of tastes corresponding to different taste modalities can be tested in engaging laboratory sessions using students themselves as test subjects. This article describes a series of experiments in which data pertaining to the detection of salty and sweet tastes are obtained, and the ability of the herb Gymnema sylvestre to disrupt the detection of sucrose is quantified. The effects of blinding and different assay designs on EC50 estimation are also investigated. The data obtained allow for substantial data analysis, including non-linear regression using fixed and free parameters to quantify dose-response relationships, and the use of often under-utilized permutation tests to determine significant differences when the underlying data display heteroscedasticity.
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Affiliation(s)
| | | | | | | | | | | | | | - Chris Shelley
- Address correspondence to: Dr. Chris Shelley, Biology Department, Franklin and Marshall College, PO Box 3003, Lancaster, PA, 17604.
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CSF-contacting neurons regulate locomotion by relaying mechanical stimuli to spinal circuits. Nat Commun 2016; 7:10866. [PMID: 26946992 PMCID: PMC4786674 DOI: 10.1038/ncomms10866] [Citation(s) in RCA: 113] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 01/28/2016] [Indexed: 12/15/2022] Open
Abstract
Throughout vertebrates, cerebrospinal fluid-contacting neurons (CSF-cNs) are ciliated cells surrounding the central canal in the ventral spinal cord. Their contribution to modulate locomotion remains undetermined. Recently, we have shown CSF-cNs modulate locomotion by directly projecting onto the locomotor central pattern generators (CPGs), but the sensory modality these cells convey to spinal circuits and their relevance to innate locomotion remain elusive. Here, we demonstrate in vivo that CSF-cNs form an intraspinal mechanosensory organ that detects spinal bending. By performing calcium imaging in moving animals, we show that CSF-cNs respond to both passive and active bending of the spinal cord. In mutants for the channel Pkd2l1, CSF-cNs lose their response to bending and animals show a selective reduction of tail beat frequency, confirming the central role of this feedback loop for optimizing locomotion. Altogether, our study reveals that CSF-cNs constitute a mechanosensory organ operating during locomotion to modulate spinal CPGs.
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71
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Kuno M, Li G, Moriura Y, Hino Y, Kawawaki J, Sakai H. Acid-inducible proton influx currents in the plasma membrane of murine osteoclast-like cells. Pflugers Arch 2016; 468:837-47. [PMID: 26843093 DOI: 10.1007/s00424-016-1796-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Revised: 01/02/2016] [Accepted: 01/25/2016] [Indexed: 01/20/2023]
Abstract
Acidification of the resorption pits, which is essential for dissolving bone, is produced by secretion of protons through vacuolar H(+)-ATPases in the plasma membrane of bone-resorbing cells, osteoclasts. Consequently, osteoclasts face highly acidic extracellular environments, where the pH gradient across the plasma membrane could generate a force driving protons into the cells. Proton influx mechanisms during the acid exposure are largely unknown, however. In this study, we investigated extracellular-acid-inducible proton influx currents in osteoclast-like cells derived from a macrophage cell line (RAW264). Decreasing extracellular pH to <5.5 induced non-ohmic inward currents. The reversal potentials depended on the pH gradients across the membrane and were independent of concentrations of Na(+), Cl(-), and HCO3 (-), suggesting that they were carried largely by protons. The acid-inducible proton influx currents were not inhibited by amiloride, a widely used blocker for cation channels/transporters, or by 4,4'-diisothiocyanato-2,2'-stilbenesulfonate(DIDS) which blocks anion channels/transporters. Additionally, the currents were not significantly affected by V-ATPase inhibitors, bafilomycin A1 and N,N'-dicyclohexylcarbodiimide. Extracellular Ca(2+) (10 mM) did not affect the currents, but 1 mM ZnCl2 decreased the currents partially. The intracellular pH in the vicinity of the plasma membrane was dropped by the acid-inducible H(+) influx currents, which caused overshoot of the voltage-gated H(+) channels after removal of acids. The H(+) influx currents were smaller in undifferentiated, mononuclear RAW cells and were negligible in COS7 cells. These data suggest that the acid-inducible H(+) influx (H(+) leak) pathway may be an additional mechanism modifying the pH environments of osteoclasts upon exposure to strong acids.
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Affiliation(s)
- Miyuki Kuno
- Department of Physiology, Osaka City University Graduate School of Medicine, 1-4-3 Asahimachi, Abeno-ku, Osaka, 545-8585, Japan.
| | - Guangshuai Li
- Department of Physiology, Osaka City University Graduate School of Medicine, 1-4-3 Asahimachi, Abeno-ku, Osaka, 545-8585, Japan
| | - Yoshie Moriura
- Department of Physiology, Osaka City University Graduate School of Medicine, 1-4-3 Asahimachi, Abeno-ku, Osaka, 545-8585, Japan
| | - Yoshiko Hino
- Department of Physiology, Osaka City University Graduate School of Medicine, 1-4-3 Asahimachi, Abeno-ku, Osaka, 545-8585, Japan
| | - Junko Kawawaki
- Central Laboratory, Osaka City University Graduate School of Medicine, Abeno-ku, Osaka, 545-8585, Japan
| | - Hiromu Sakai
- Department of Physiology, Osaka City University Graduate School of Medicine, 1-4-3 Asahimachi, Abeno-ku, Osaka, 545-8585, Japan
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72
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Epstein JB, Smutzer G, Doty RL. Understanding the impact of taste changes in oncology care. Support Care Cancer 2016; 24:1917-31. [DOI: 10.1007/s00520-016-3083-8] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Accepted: 01/07/2016] [Indexed: 12/22/2022]
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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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74
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Abreu MS, Giacomini ACV, Gusso D, Rosa JGS, Koakoski G, Kalichak F, Idalêncio R, Oliveira TA, Barcellos HHA, Bonan CD, Barcellos LJG. Acute exposure to waterborne psychoactive drugs attract zebrafish. Comp Biochem Physiol C Toxicol Pharmacol 2016; 179:37-43. [PMID: 26325205 DOI: 10.1016/j.cbpc.2015.08.009] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Revised: 08/20/2015] [Accepted: 08/23/2015] [Indexed: 01/08/2023]
Abstract
Psychotropic medications are widely used, and their prescription has increased worldwide, consequently increasing their presence in aquatic environments. Therefore, aquatic organisms can be exposed to psychotropic drugs that may be potentially dangerous, raising the question of whether these drugs are attractive or aversive to fish. To answer this question, adult zebrafish were tested in a chamber that allows the fish to escape or seek a lane of contaminated water. These attraction and aversion paradigms were evaluated by exposing the zebrafish to the presence of acute contamination with these compounds. The zebrafish were attracted by certain concentrations of diazepam, fluoxetine, risperidone and buspirone, which were most likely detected by olfaction, because this behavior was absent in anosmic fish. These findings suggest that despite their deleterious effects, certain psychoactive drugs attract fish.
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Affiliation(s)
- Murilo S Abreu
- Programa de Pós-Graduação em Farmacologia, Universidade Federal de Santa Maria (UFSM), Av. Roraima, 1000, Cidade Universitária, Camobi, Santa Maria, RS, 97105-900, Brazil
| | - Ana Cristina V Giacomini
- Programa de Pós-Graduação em Farmacologia, Universidade Federal de Santa Maria (UFSM), Av. Roraima, 1000, Cidade Universitária, Camobi, Santa Maria, RS, 97105-900, Brazil; Universidade de Passo Fundo (UPF), BR 285, Bairro São José, Passo Fundo, RS, 99052-900, Brazil
| | - Darlan Gusso
- Universidade de Passo Fundo (UPF), BR 285, Bairro São José, Passo Fundo, RS, 99052-900, Brazil
| | - João G S Rosa
- Programa de Pós-Graduação em Farmacologia, Universidade Federal de Santa Maria (UFSM), Av. Roraima, 1000, Cidade Universitária, Camobi, Santa Maria, RS, 97105-900, Brazil
| | - Gessi Koakoski
- Programa de Pós-Graduação em Farmacologia, Universidade Federal de Santa Maria (UFSM), Av. Roraima, 1000, Cidade Universitária, Camobi, Santa Maria, RS, 97105-900, Brazil
| | - Fabiana Kalichak
- Programa de Pós-Graduação em Farmacologia, Universidade Federal de Santa Maria (UFSM), Av. Roraima, 1000, Cidade Universitária, Camobi, Santa Maria, RS, 97105-900, Brazil
| | - Renan Idalêncio
- Universidade de Passo Fundo (UPF), BR 285, Bairro São José, Passo Fundo, RS, 99052-900, Brazil; Programa de Pós-Graduação em Bioexperimentação, Universidade de Passo Fundo (UPF), Hospital Veterinário, BR 285, Bairro São José, Passo Fundo, RS, 99052-900, Brazil
| | - Thiago A Oliveira
- Programa de Pós-Graduação em Farmacologia, Universidade Federal de Santa Maria (UFSM), Av. Roraima, 1000, Cidade Universitária, Camobi, Santa Maria, RS, 97105-900, Brazil
| | - Heloísa H A Barcellos
- Programa de Pós-Graduação em Farmacologia, Universidade Federal de Santa Maria (UFSM), Av. Roraima, 1000, Cidade Universitária, Camobi, Santa Maria, RS, 97105-900, Brazil; Universidade de Passo Fundo (UPF), BR 285, Bairro São José, Passo Fundo, RS, 99052-900, Brazil
| | - Carla D Bonan
- Laboratório de Neuroquímica e Psicofarmacologia, Programa de Pós-Graduação em Biologia Celular e Molecular, Faculdade de Biociências, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Av. Ipiranga, 6681, Porto Alegre, RS, Brazil
| | - Leonardo J G Barcellos
- Programa de Pós-Graduação em Farmacologia, Universidade Federal de Santa Maria (UFSM), Av. Roraima, 1000, Cidade Universitária, Camobi, Santa Maria, RS, 97105-900, Brazil; Universidade de Passo Fundo (UPF), BR 285, Bairro São José, Passo Fundo, RS, 99052-900, Brazil; Programa de Pós-Graduação em Bioexperimentação, Universidade de Passo Fundo (UPF), Hospital Veterinário, BR 285, Bairro São José, Passo Fundo, RS, 99052-900, Brazil.
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The K+ channel KIR2.1 functions in tandem with proton influx to mediate sour taste transduction. Proc Natl Acad Sci U S A 2015; 113:E229-38. [PMID: 26627720 DOI: 10.1073/pnas.1514282112] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Sour taste is detected by a subset of taste cells on the tongue and palate epithelium that respond to acids with trains of action potentials. Entry of protons through a Zn(2+)-sensitive proton conductance that is specific to sour taste cells has been shown to be the initial event in sour taste transduction. Whether this conductance acts in concert with other channels sensitive to changes in intracellular pH, however, is not known. Here, we show that intracellular acidification generates excitatory responses in sour taste cells, which can be attributed to block of a resting K(+) current. We identify KIR2.1 as the acid-sensitive K(+) channel in sour taste cells using pharmacological and RNA expression profiling and confirm its contribution to sour taste with tissue-specific knockout of the Kcnj2 gene. Surprisingly, acid sensitivity is not conferred on sour taste cells by the specific expression of Kir2.1, but by the relatively small magnitude of the current, which makes the cells exquisitely sensitive to changes in intracellular pH. Consistent with a role of the K(+) current in amplifying the sensory response, entry of protons through the Zn(2+)-sensitive conductance produces a transient block of the KIR2.1 current. The identification in sour taste cells of an acid-sensitive K(+) channel suggests a mechanism for amplification of sour taste and may explain why weak acids that produce intracellular acidification, such as acetic acid, taste more sour than strong acids.
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Orts-Del'Immagine A, Seddik R, Tell F, Airault C, Er-Raoui G, Najimi M, Trouslard J, Wanaverbecq N. A single polycystic kidney disease 2-like 1 channel opening acts as a spike generator in cerebrospinal fluid-contacting neurons of adult mouse brainstem. Neuropharmacology 2015. [PMID: 26220314 DOI: 10.1016/j.neuropharm.2015.07.030] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Cerebrospinal fluid contacting neurons (CSF-cNs) are found around the central canal of all vertebrates. They present a typical morphology, with a single dendrite that projects into the cavity and ends in the CSF with a protuberance. These anatomical features have led to the suggestion that CSF-cNs might have sensory functions, either by sensing CSF movement or composition, but the physiological mechanisms for any such role are unknown. This hypothesis was recently supported by the demonstration that in several vertebrate species medullo-spinal CSF-cNs selectively express Polycystic Kidney Disease 2-Like 1 proteins (PKD2L1). PKD2L1 are members of the 'transient receptor potential (TRP)' superfamily, form non-selective cationic channels of high conductance, are regulated by various stimuli including protons and are therefore suggested to act as sensory receptors. Using patch-clamp whole-cell recordings of CSF-cNs in brainstem slices obtained from wild type and mutant PKD2L1 mice, we demonstrate that spontaneously active unitary currents in CSF-cNs are due to PKD2L1 channels that are capable, with a single opening, of triggering action potentials. Thus PKD2L1 might contribute to the setting of CSF-cN spiking activity. We also reveal that CSF-cNs have the capacity of discriminating between alkalinization and acidification following activation of specific conductances (PKD2L1 vs. ASIC) generating specific responses. Altogether, this study reinforces the idea that CSF-cNs represent sensory neurons intrinsic to the central nervous system and suggests a role for PKD2L1 channels as spike generators.
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Affiliation(s)
| | - Riad Seddik
- Aix Marseille Université, PPSN EA 4674, 13397, Marseille, France
| | - Fabien Tell
- Aix Marseille Université, CNRS, CRN2M UMR 7286, 13344, Marseille, France
| | - Coraline Airault
- Aix Marseille Université, PPSN EA 4674, 13397, Marseille, France
| | - Ghizlane Er-Raoui
- Aix Marseille Université, PPSN EA 4674, 13397, Marseille, France; Université Sultan Moulay Slimane, 23000, Béni Mellal, Morocco
| | - Mohamed Najimi
- Université Sultan Moulay Slimane, 23000, Béni Mellal, Morocco
| | - Jérôme Trouslard
- Aix Marseille Université, PPSN EA 4674, 13397, Marseille, France.
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Beckett EL, Martin C, Yates Z, Veysey M, Duesing K, Lucock M. Bitter taste genetics--the relationship to tasting, liking, consumption and health. Food Funct 2015; 5:3040-54. [PMID: 25286017 DOI: 10.1039/c4fo00539b] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Bitter is the most complex of human tastes, and is arguably the most important. Aversion to bitter taste is important for detecting toxic compounds in food; however, many beneficial nutrients also taste bitter and these may therefore also be avoided as a consequence of bitter taste. While many polymorphisms in TAS2R genes may result in phenotypic differences that influence the range and sensitivity of bitter compounds detected, the full extent to which individuals differ in their abilities to detect bitter compounds remains unknown. Simple logic suggests that taste phenotypes influence food preferences, intake and consequently health status. However, it is becoming clear that genetics only plays a partial role in predicting preference, intake and health outcomes, and the complex, pleiotropic relationships involved are yet to be fully elucidated.
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Affiliation(s)
- Emma L Beckett
- School of Environmental and Life Sciences, University of Newcastle, Brush Rd, Ourimbah, NSW 2258, Australia.
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Bushman JD, Ye W, Liman ER. A proton current associated with sour taste: distribution and functional properties. FASEB J 2015; 29:3014-26. [PMID: 25857556 DOI: 10.1096/fj.14-265694] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Accepted: 03/11/2015] [Indexed: 02/06/2023]
Abstract
Sour taste is detected by taste receptor cells that respond to acids through yet poorly understood mechanisms. The cells that detect sour express the protein PKD2L1, which is not the sour receptor but nonetheless serves as a useful marker for sour cells. By use of mice in which the PKD2L1 promoter drives expression of yellow fluorescent protein, we previously reported that sour taste cells from circumvallate papillae in the posterior tongue express a proton current. To establish a correlation between this current and sour transduction, we examined its distribution by patch-clamp recording. We find that the current is present in PKD2L1-expressing taste cells from mouse circumvallate, foliate, and fungiform papillae but not in a variety of other cells, including spinal cord neurons that express PKD2L1. We describe biophysical properties of the current, including pH-dependent Zn(2+) inhibition, lack of voltage-dependent gating, and activation at modest pH values (6.5) that elicit action potentials in isolated cells. Consistent with a channel that is constitutively open, the cytosol of sour taste cells is acidified. These data define a functional signature for the taste cell proton current and indicate that its expression is mostly restricted to the subset of taste cells that detect sour.
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Affiliation(s)
- Jeremy D Bushman
- Section of Neurobiology, Department of Biological Sciences, University of Southern California, Los Angeles, California, USA
| | - Wenlei Ye
- Section of Neurobiology, Department of Biological Sciences, University of Southern California, Los Angeles, California, USA
| | - Emily R Liman
- Section of Neurobiology, Department of Biological Sciences, University of Southern California, Los Angeles, California, USA
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Abstract
Levels of obesity have reached epidemic proportions on a global scale, which has led to considerable increases in health problems and increased risk of several diseases, including cardiovascular and pulmonary diseases, cancer and diabetes mellitus. People with obesity consume more food than is needed to maintain an ideal body weight, despite the discrimination that accompanies being overweight and the wealth of available information that overconsumption is detrimental to health. The relationship between energy expenditure and energy intake throughout an individual's lifetime is far more complicated than previously thought. An improved comprehension of the relationships between taste, palatability, taste receptors and hedonic responses to food might lead to increased understanding of the biological underpinnings of energy acquisition, as well as why humans sometimes eat more than is needed and more than we know is healthy. This Review discusses the role of taste receptors in the tongue, gut, pancreas and brain and their hormonal involvement in taste perception, as well as the relationship between taste perception, overeating and the development of obesity.
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Affiliation(s)
- Sara Santa-Cruz Calvo
- Laboratory of Clinical Investigation, National Institute on Aging, NIH, Biomedical Research Center, Room 09B133, 251 Bayview Boulevard, Suite 100, Baltimore, MD 21224-6825, USA
| | - Josephine M Egan
- Laboratory of Clinical Investigation, National Institute on Aging, NIH, Biomedical Research Center, Room 09B133, 251 Bayview Boulevard, Suite 100, Baltimore, MD 21224-6825, USA
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81
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Ishimaru Y. Molecular mechanisms underlying the reception and transmission of sour taste information. Biosci Biotechnol Biochem 2015; 79:171-6. [DOI: 10.1080/09168451.2014.975187] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Abstract
Taste enables organisms to determine the properties of ingested substances by conveying information regarding the five basic taste modalities: sweet, salty, sour, bitter, and umami. The sweet, salty, and umami taste modalities convey the carbohydrate, electrolyte, and glutamate content of food, indicating its desirability and stimulating appetitive responses. The sour and bitter modalities convey the acidity of food and the presence of potential toxins, respectively, stimulating aversive responses to such tastes. In recent years, the receptors mediating sweet, bitter, and umami tastes have been identified as members of the T1R and T2R G-protein-coupled receptor families; however, the molecular mechanisms underlying sour taste detection have yet to be clearly elucidated. This review covers the molecular mechanisms proposed to mediate the detection and transmission of sour stimuli, focusing on polycystic kidney disease 1-like 3 (Pkd1l3), Pkd2l1, and carbonic anhydrase 4 (Car4).
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Affiliation(s)
- Yoshiro Ishimaru
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Japan
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82
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Doty RL. Neurotoxic exposure and impairment of the chemical senses of taste and smell. HANDBOOK OF CLINICAL NEUROLOGY 2015; 131:299-324. [PMID: 26563795 DOI: 10.1016/b978-0-444-62627-1.00016-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The chemical senses of taste and smell determine the flavor of foods and beverages, guide appropriate food intake, and warn of such environmental hazards as spoiled or poisonous food, leaking natural gas, smoke, and airborne pollutants. This chapter addresses the influences of neurotoxic exposures on human chemoreception and provides basic information on the adverse influences of such exposures on rodent epithelia. The focus of the chapter is in olfaction, given dearth of empiric research on the effects of neurotoxic chemical exposures on the sense of taste, i.e., sweet, sour, bitter, salty, and savory sensations. As will be apparent from the chapter, numerous neurotoxins--many of which are encountered in industrial workplaces--alter the ability to smell, including solvents, metals, and particulate matter. The olfactory system is particularly vulnerable to such agents since its receptors are more or less directly exposed to the outside environment. Importantly, some such agents can enter the brain via the olfactory nerve or surrounding perineural spaces, bypassing the blood-brain barrier and damaging central nervous system structures and inducing pathologic processes that appear to be similar to those seen in neurodegenerative diseases such as Alzheimer's and Parkinson's.
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Affiliation(s)
- Richard L Doty
- Smell and Taste Center, Department of Otorhinolaryngology; Head and Neck Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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83
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Abstract
TRP channels are expressed in taste buds, nerve fibers, and keratinocytes in the oronasal cavity. These channels play integral roles in transducing chemical stimuli, giving rise to sensations of taste, irritation, warmth, coolness, and pungency. Specifically, TRPM5 acts downstream of taste receptors in the taste transduction pathway. TRPM5 channels convert taste-evoked intracellular Ca(2+) release into membrane depolarization to trigger taste transmitter secretion. PKD2L1 is expressed in acid-sensitive (sour) taste bud cells but is unlikely to be the transducer for sour taste. TRPV1 is a receptor for pungent chemical stimuli such as capsaicin and for several irritants (chemesthesis). It is controversial whether TRPV1 is present in the taste buds and plays a direct role in taste. Instead, TRPV1 is expressed in non-gustatory sensory afferent fibers and in keratinocytes of the oronasal cavity. In many sensory fibers and epithelial cells lining the oronasal cavity, TRPA1 is also co-expressed with TRPV1. As with TRPV1, TRPA1 transduces a wide variety of irritants and, in combination with TRPV1, assures that there is a broad response to noxious chemical stimuli. Other TRP channels, including TRPM8, TRPV3, and TRPV4, play less prominent roles in chemesthesis and no known role in taste, per se. The pungency of foods and beverages is likely highly influenced by the temperature at which they are consumed, their acidity, and, for beverages, their carbonation. All these factors modulate the activity of TRP channels in taste buds and in the oronasal mucosa.
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Affiliation(s)
- Stephen D Roper
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, 1600 NW 10th Ave., Miami, FL, 33136, USA,
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84
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Permeation, regulation and control of expression of TRP channels by trace metal ions. Pflugers Arch 2014; 467:1143-64. [PMID: 25106481 PMCID: PMC4435931 DOI: 10.1007/s00424-014-1590-3] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Revised: 07/10/2014] [Accepted: 07/13/2014] [Indexed: 01/26/2023]
Abstract
Transient receptor potential (TRP) channels form a diverse family of cation channels comprising 28 members in mammals. Although some TRP proteins can only be found on intracellular membranes, most of the TRP protein isoforms reach the plasma membrane where they form ion channels and control a wide number of biological processes. There, their involvement in the transport of cations such as calcium and sodium has been well documented. However, a growing number of studies have started to expand our understanding of these proteins by showing that they also transport other biologically relevant metal ions like zinc, magnesium, manganese and cobalt. In addition to this newly recognized property, the activity and expression of TRP channels can be regulated by metal ions like magnesium, gadolinium, lanthanum or cisplatin. The aim of this review is to highlight the complex relationship between metal ions and TRP channels.
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Abstract
Five canonical tastes, bitter, sweet, umami (amino acid), salty, and sour (acid), are detected by animals as diverse as fruit flies and humans, consistent with a near-universal drive to consume fundamental nutrients and to avoid toxins or other harmful compounds. Surprisingly, despite this strong conservation of basic taste qualities between vertebrates and invertebrates, the receptors and signaling mechanisms that mediate taste in each are highly divergent. The identification over the last two decades of receptors and other molecules that mediate taste has led to stunning advances in our understanding of the basic mechanisms of transduction and coding of information by the gustatory systems of vertebrates and invertebrates. In this Review, we discuss recent advances in taste research, mainly from the fly and mammalian systems, and we highlight principles that are common across species, despite stark differences in receptor types.
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Affiliation(s)
- Emily R Liman
- Section of Neurobiology, University of Southern California, Los Angeles, CA 90089, USA.
| | - Yali V Zhang
- Neuroscience Research Institute, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Craig Montell
- Neuroscience Research Institute, University of California Santa Barbara, Santa Barbara, CA 93106, USA; Department of Molecular, Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA 93106, USA.
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Djenoune L, Khabou H, Joubert F, Quan FB, Nunes Figueiredo S, Bodineau L, Del Bene F, Burcklé C, Tostivint H, Wyart C. Investigation of spinal cerebrospinal fluid-contacting neurons expressing PKD2L1: evidence for a conserved system from fish to primates. Front Neuroanat 2014; 8:26. [PMID: 24834029 PMCID: PMC4018565 DOI: 10.3389/fnana.2014.00026] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2014] [Accepted: 04/10/2014] [Indexed: 12/11/2022] Open
Abstract
Over 90 years ago, Kolmer and Agduhr identified spinal cerebrospinal fluid-contacting neurons (CSF-cNs) based on their morphology and location within the spinal cord. In more than 200 vertebrate species, they observed ciliated neurons around the central canal that extended a brush of microvilli into the cerebrospinal fluid (CSF). Although their morphology is suggestive of a primitive sensory cell, their function within the vertebrate spinal cord remains unknown. The identification of specific molecular markers for these neurons in vertebrates would benefit the investigation of their physiological roles. PKD2L1, a transient receptor potential channel that could play a role as a sensory receptor, has been found in cells contacting the central canal in mouse. In this study, we demonstrate that PKD2L1 is a specific marker for CSF-cNs in the spinal cord of mouse (Mus musculus), macaque (Macaca fascicularis) and zebrafish (Danio rerio). In these species, the somata of spinal PKD2L1+ CSF-cNs were located below or within the ependymal layer and extended an apical bulbous extension into the central canal. We found GABAergic PKD2L1-expressing CSF-cNs in all three species. We took advantage of the zebrafish embryo for its transparency and rapid development to identify the progenitor domains from which pkd2l1+ CSF-cNs originate. pkd2l1+ CSF-cNs were all GABAergic and organized in two rows—one ventral and one dorsal to the central canal. Their location and marker expression is consistent with previously described Kolmer–Agduhr cells. Accordingly, pkd2l1+ CSF-cNs were derived from the progenitor domains p3 and pMN defined by the expression of nkx2.2a and olig2 transcription factors, respectively. Altogether our results suggest that a system of CSF-cNs expressing the PKD2L1 channel is conserved in the spinal cord across bony vertebrate species.
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Affiliation(s)
- Lydia Djenoune
- Institut du Cerveau et de la Moelle Épinière, Hôpital de la Pitié-Salpêtrière Paris, France ; Institut National de la Santé et de la Recherche Médicale UMR 1127 Paris, France ; Centre National de la Recherche Scientifique UMR 7225 Paris, France ; UPMC Univ. Paris 06 Paris, France ; Muséum National d'Histoire Naturelle Paris, France ; Centre National de la Recherche Scientifique UMR 7221 Paris, France
| | - Hanen Khabou
- Institut du Cerveau et de la Moelle Épinière, Hôpital de la Pitié-Salpêtrière Paris, France ; Institut National de la Santé et de la Recherche Médicale UMR 1127 Paris, France ; Centre National de la Recherche Scientifique UMR 7225 Paris, France ; UPMC Univ. Paris 06 Paris, France
| | - Fanny Joubert
- UPMC Univ. Paris 06 Paris, France ; Institut National de la Santé et de la Recherche Médicale UMR S 1158 Paris, France
| | - Feng B Quan
- Muséum National d'Histoire Naturelle Paris, France ; Centre National de la Recherche Scientifique UMR 7221 Paris, France
| | - Sophie Nunes Figueiredo
- Institut du Cerveau et de la Moelle Épinière, Hôpital de la Pitié-Salpêtrière Paris, France ; Institut National de la Santé et de la Recherche Médicale UMR 1127 Paris, France ; Centre National de la Recherche Scientifique UMR 7225 Paris, France ; UPMC Univ. Paris 06 Paris, France
| | - Laurence Bodineau
- UPMC Univ. Paris 06 Paris, France ; Institut National de la Santé et de la Recherche Médicale UMR S 1158 Paris, France
| | - Filippo Del Bene
- Institut Curie Paris, France ; Centre National de la Recherche Scientifique UMR 3215 Paris, France ; Institut National de la Santé et de la Recherche Médicale U 934 Paris, France
| | - Céline Burcklé
- Institut du Cerveau et de la Moelle Épinière, Hôpital de la Pitié-Salpêtrière Paris, France ; Institut National de la Santé et de la Recherche Médicale UMR 1127 Paris, France ; Centre National de la Recherche Scientifique UMR 7225 Paris, France ; UPMC Univ. Paris 06 Paris, France
| | - Hervé Tostivint
- Muséum National d'Histoire Naturelle Paris, France ; Centre National de la Recherche Scientifique UMR 7221 Paris, France
| | - Claire Wyart
- Institut du Cerveau et de la Moelle Épinière, Hôpital de la Pitié-Salpêtrière Paris, France ; Institut National de la Santé et de la Recherche Médicale UMR 1127 Paris, France ; Centre National de la Recherche Scientifique UMR 7225 Paris, France ; UPMC Univ. Paris 06 Paris, France
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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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89
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Charlu S, Wisotsky Z, Medina A, Dahanukar A. Acid sensing by sweet and bitter taste neurons in Drosophila melanogaster. Nat Commun 2013; 4:2042. [PMID: 23783889 PMCID: PMC3710667 DOI: 10.1038/ncomms3042] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Accepted: 05/17/2013] [Indexed: 01/13/2023] Open
Abstract
Drosophila melanogaster can taste various compounds and separate them into few basic categories such as sweet, bitter and salt taste. Here we investigate mechanisms underlying acid detection in Drosophila and report that the fly displays strong taste aversion to common carboxylic acids. We find that acid tastants act by the activation of a subset of bitter neurons and inhibition of sweet neurons. Bitter neurons begin to respond at pH 5 and show an increase in spike frequency as the extracellular pH drops, which does not rely on previously identified chemoreceptors. Notably, sweet neuron activity depends on the balance of sugar and acid tastant concentrations. This is independent of bitter neuron firing, and allows the fly to avoid acid-laced food sources even in the absence of functional bitter neurons. The two mechanisms may allow the fly to better evaluate the risk of ingesting acidic foods and modulate its feeding decisions accordingly.
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Affiliation(s)
- Sandhya Charlu
- Biomedical Sciences Graduate Program, School of Medicine, 900 University Avenue, University of California-Riverside, CA 92521, USA
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90
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Yu Y, Ulbrich MH, Li MH, Dobbins S, Zhang WK, Tong L, Isacoff EY, Yang J. Molecular mechanism of the assembly of an acid-sensing receptor ion channel complex. Nat Commun 2013; 3:1252. [PMID: 23212381 PMCID: PMC3575195 DOI: 10.1038/ncomms2257] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Accepted: 11/05/2012] [Indexed: 12/11/2022] Open
Abstract
Polycystic kidney disease (PKD) family proteins associate with transient receptor potential (TRP) channel family proteins to form functionally important complexes. PKD proteins differ from known ion channel-forming proteins and are generally thought to act as membrane receptors. Here we find that PKD1L3, a PKD protein, functions as a channel-forming subunit in an acid-sensing heteromeric complex formed by PKD1L3 and TRPP3, a TRP channel protein. Single amino-acid mutations in the putative pore region of both proteins alter the channel's ion selectivity. The PKD1L3/TRPP3 complex in the plasma membrane of live cells contains one PKD1L3 and three TRPP3. A TRPP3 C-terminal coiled-coil domain forms a trimer in solution and in crystal, and has a crucial role in the assembly and surface expression of the PKD1L3/TRPP3 complex. These results demonstrate that PKD subunits constitute a new class of channel-forming proteins, enriching our understanding of the function of PKD proteins and PKD/TRPP complexes.
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Affiliation(s)
- Yong Yu
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
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91
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Hirohashi N, Alvarez L, Shiba K, Fujiwara E, Iwata Y, Mohri T, Inaba K, Chiba K, Ochi H, Supuran CT, Kotzur N, Kakiuchi Y, Kaupp UB, Baba SA. Sperm from sneaker male squids exhibit chemotactic swarming to CO₂. Curr Biol 2013; 23:775-81. [PMID: 23583548 DOI: 10.1016/j.cub.2013.03.040] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2011] [Revised: 01/28/2013] [Accepted: 03/14/2013] [Indexed: 02/07/2023]
Abstract
Behavioral traits of sperm are adapted to the reproductive strategy that each species employs. In polyandrous species, spermatozoa often form motile clusters, which might be advantageous for competing with sperm from other males. Despite this presumed advantage for reproductive success, little is known about how sperm form such functional assemblies. Previously, we reported that males of the coastal squid Loligo bleekeri produce two morphologically different euspermatozoa that are linked to distinctly different mating behaviors. Consort and sneaker males use two distinct insemination sites, one inside and one outside the female's body, respectively. Here, we show that sperm release a self-attracting molecule that causes only sneaker sperm to swarm. We identified CO2 as the sperm chemoattractant and membrane-bound flagellar carbonic anhydrase as its sensor. Downstream signaling results from the generation of extracellular H(+), intracellular acidosis, and recovery from acidosis. These signaling events elicit Ca(2+)-dependent turning behavior, resulting in chemotactic swarming. These results illuminate the bifurcating evolution of sperm underlying the distinct fertilization strategies of this species.
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Affiliation(s)
- Noritaka Hirohashi
- Oki Marine Biological Station, Education and Research Center for Biological Resources, Shimane University, 194 Kamo, Okinoshima-cho, Oki, Shimane 685-0024, Japan.
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92
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DeCoursey TE. Voltage-gated proton channels: molecular biology, physiology, and pathophysiology of the H(V) family. Physiol Rev 2013; 93:599-652. [PMID: 23589829 PMCID: PMC3677779 DOI: 10.1152/physrev.00011.2012] [Citation(s) in RCA: 178] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Voltage-gated proton channels (H(V)) are unique, in part because the ion they conduct is unique. H(V) channels are perfectly selective for protons and have a very small unitary conductance, both arguably manifestations of the extremely low H(+) concentration in physiological solutions. They open with membrane depolarization, but their voltage dependence is strongly regulated by the pH gradient across the membrane (ΔpH), with the result that in most species they normally conduct only outward current. The H(V) channel protein is strikingly similar to the voltage-sensing domain (VSD, the first four membrane-spanning segments) of voltage-gated K(+) and Na(+) channels. In higher species, H(V) channels exist as dimers in which each protomer has its own conduction pathway, yet gating is cooperative. H(V) channels are phylogenetically diverse, distributed from humans to unicellular marine life, and perhaps even plants. Correspondingly, H(V) functions vary widely as well, from promoting calcification in coccolithophores and triggering bioluminescent flashes in dinoflagellates to facilitating killing bacteria, airway pH regulation, basophil histamine release, sperm maturation, and B lymphocyte responses in humans. Recent evidence that hH(V)1 may exacerbate breast cancer metastasis and cerebral damage from ischemic stroke highlights the rapidly expanding recognition of the clinical importance of hH(V)1.
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Affiliation(s)
- Thomas E DeCoursey
- Dept. of Molecular Biophysics and Physiology, Rush University Medical Center HOS-036, 1750 West Harrison, Chicago, IL 60612, USA.
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93
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Nilius B, Appendino G. Spices: the savory and beneficial science of pungency. Rev Physiol Biochem Pharmacol 2013; 164:1-76. [PMID: 23605179 DOI: 10.1007/112_2013_11] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Spicy food does not only provide an important hedonic input in daily life, but has also been anedoctically associated to beneficial effects on our health. In this context, the discovery of chemesthetic trigeminal receptors and their spicy ligands has provided the mechanistic basis and the pharmacological means to investigate this enticing possibility. This review discusses in molecular terms the connection between the neurophysiology of pungent spices and the "systemic" effects associated to their trigeminality. It commences with a cultural and historical overview on the Western fascination for spices, and, after analysing in detail the mechanisms underlying the trigeminality of food, the main dietary players from the transient receptor potential (TRP) family of cation channels are introduced, also discussing the "alien" distribution of taste receptors outside the oro-pharingeal cavity. The modulation of TRPV1 and TRPA1 by spices is next described, discussing how spicy sensations can be turned into hedonic pungency, and analyzing the mechanistic bases for the health benefits that have been associated to the consumption of spices. These include, in addition to a beneficial modulation of gastro-intestinal and cardio-vascular function, slimming, the optimization of skeletal muscle performance, the reduction of chronic inflammation, and the prevention of metabolic syndrome and diabetes. We conclude by reviewing the role of electrophilic spice constituents on cancer prevention in the light of their action on pro-inflammatory and pro-cancerogenic nuclear factors like NFκB, and on their interaction with the electrophile sensor protein Keap1 and the ensuing Nrf2-mediated transcriptional activity. Spicy compounds have a complex polypharmacology, and just like any other bioactive agent, show a balance of beneficial and bad actions. However, at least for moderate consumption, the balance seems definitely in favour of the positive side, suggesting that a spicy diet, a caveman-era technology, could be seriously considered in addition to caloric control and exercise as a measurement to prevent and control many chronic diseases associate to malnutrition from a Western diet.
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Affiliation(s)
- Bernd Nilius
- KU Leuven Department of Cellular and Molecular Medicine, Laboratory of Ion Channel Research, Leuven, Belgium,
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94
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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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95
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Adachi R, Sasaki Y, Morita H, Komai M, Shirakawa H, Goto T, Furuyama A, Isono K. Behavioral analysis of Drosophila transformants expressing human taste receptor genes in the gustatory receptor neurons. J Neurogenet 2012; 26:198-205. [PMID: 22794107 DOI: 10.3109/01677063.2012.690254] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Transgenic Drosophila expressing human T2R4 and T2R38 bitter-taste receptors or PKD2L1 sour-taste receptor in the fly gustatory receptor neurons and other tissues were prepared using conventional Gal4/UAS binary system. Molecular analysis showed that the transgene mRNAs are expressed according to the tissue specificity of the Gal4 drivers. Transformants expressing the transgene taste receptors in the fly taste neurons were then studied by a behavioral assay to analyze whether transgene chemoreceptors are functional and coupled to the cell response. Since wild-type flies show strong aversion against the T2R ligands as in mammals, the authors analyzed the transformants where the transgenes are expressed in the fly sugar receptor neurons so that they promote feeding ligand-dependently if they are functional and activate the neurons. Although the feeding preference varied considerably among different strains and individuals, statistical analysis using large numbers of transformants indicated that transformants expressing T2R4 showed a small but significant increase in the preference for denatonium and quinine, the T2R4 ligands, as compared to the control flies, whereas transformants expressing T2R38 did not. Similarly, transformants expressing T2R38 and PKD2L1 also showed a similar preference increase for T2R38-specific ligand phenylthiocarbamide (PTC) and a sour-taste ligand, citric acid, respectively. Taken together, the transformants expressing mammalian taste receptors showed a small but significant increase in the feeding preference that is taste receptor and also ligand dependent. Although future improvements are required to attain performance comparable to the endogenous robust response, Drosophila taste neurons may serve as a potential in vivo heterologous expression system for analyzing chemoreceptor function.
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Affiliation(s)
- Ryota Adachi
- Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyacho,Aoba-ku, Sendai, Japan
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Voigt A, Hübner S, Lossow K, Hermans-Borgmeyer I, Boehm U, Meyerhof W. Genetic labeling of Tas1r1 and Tas2r131 taste receptor cells in mice. Chem Senses 2012; 37:897-911. [PMID: 23010799 DOI: 10.1093/chemse/bjs082] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Characterization of the peripheral taste system relies on the identification and visualization of the different taste bud cell types. So far, genetic strategies to label taste receptor cells are limited to sweet, sour, and salty detecting cells. To visualize Tas1r1 umami and Tas2r131 bitter sensing cells, we generated animals in which the Tas1r1 and Tas2r131 open reading frames are replaced by expression cassettes containing the fluorescent proteins mCherry or hrGFP, respectively. These animals enabled us to visualize and quantify the entire oral Tas1r1 and Tas2r131 cell populations. Tas1r1-mCherry cells were predominantly detected in fungiform papillae, whereas Tas2r131-hrGFP cells, which are ~4-fold more abundant, were mainly present in foliate and vallate papillae. In the palate, both cell types were similarly distributed. Mice carrying both recombinant alleles demonstrated completely segregated Tas1r1 and Tas2r131 cell populations. Only ~50% of the entire bitter cell population expressed hrGFP, indicating that bitter taste receptor cells express a subset of the bitter receptor repertoire. In extragustatory tissues, mCherry fluorescence was observed in testis and hrGFP fluorescence in testis, thymus, vomeronasal organ, and respiratory epithelium, suggesting that only few extraoral sites express Tas2r131 and Tas1r1 receptors at levels comparable to taste tissue.
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Affiliation(s)
- Anja Voigt
- Department of Molecular Genetics, German Institute of Human Nutrition Potsdam-Rehbruecke (DIfE), Arthur-Scheunert-Allee 114-116, 14558 Nuthetal, Germany
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97
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Desimone JA, Ren Z, Phan THT, Heck GL, Mummalaneni S, Lyall V. Changes in taste receptor cell [Ca2+]i modulate chorda tympani responses to salty and sour taste stimuli. J Neurophysiol 2012; 108:3206-20. [PMID: 22956787 DOI: 10.1152/jn.00916.2011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The relationship between taste receptor cell (TRC) Ca(2+) concentration ([Ca(2+)](i)) and rat chorda tympani (CT) nerve responses to salty [NaCl and NaCl+benzamil (Bz)] and sour (HCl, CO(2), and acetic acid) taste stimuli was investigated before and after lingual application of ionomycin+Ca(2+), 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid acetoxymethyl ester (BAPTA-AM), U73122 (phospholipase C blocker), and thapsigargin (Ca(2+)-ATPase inhibitor) under open-circuit or lingual voltage-clamp conditions. An increase in TRC [Ca(2+)](i) attenuated the tonic Bz-sensitive NaCl CT response and the apical membrane Na(+) conductance. A decrease in TRC [Ca(2+)](i) enhanced the tonic Bz-sensitive and Bz-insensitive NaCl CT responses and apical membrane Na(+) conductance but did not affect CT responses to KCl or NH(4)Cl. An increase in TRC [Ca(2+)](i) did not alter the phasic response but attenuated the tonic CT response to acidic stimuli. A decrease in [Ca(2+)](i) did not alter the phasic response but attenuated the tonic CT response to acidic stimuli. In a subset of TRCs, a positive relationship between [H(+)](i) and [Ca(2+)](i) was obtained using in vitro imaging techniques. U73122 inhibited the tonic CT responses to NaCl, and thapsigargin inhibited the tonic CT responses to salty and sour stimuli. The results suggest that salty and sour taste qualities are transduced by [Ca(2+)](i)-dependent and [Ca(2+)](i)-independent mechanisms. Changes in TRC [Ca(2+)](i) in a BAPTA-sensitive cytosolic compartment regulate ion channels and cotransporters involved in the salty and sour taste transduction mechanisms and in neural adaptation. Changes in TRC [Ca(2+)](i) in a separate subcompartment, sensitive to inositol trisphosphate and thapsigargin but inaccessible to BAPTA, are associated with neurotransmitter release.
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Affiliation(s)
- John A Desimone
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, VA, USA
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98
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Yamamoto K, Ishimaru Y. Oral and extra-oral taste perception. Semin Cell Dev Biol 2012; 24:240-6. [PMID: 22963927 DOI: 10.1016/j.semcdb.2012.08.005] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Accepted: 08/20/2012] [Indexed: 10/27/2022]
Abstract
Of the five basic taste qualities, the molecular mechanisms underlying sweet, bitter, and umami (savory) taste perception have been extensively elucidated, including the taste receptors and downstream signal transduction molecules. Recent studies have revealed that these taste-related molecules play important roles not only in the oral cavity but also in a variety of tissues including the respiratory tract, stomach, intestines, pancreas, liver, kidney, testes, and brain. This review covers the current knowledge regarding the physiological roles of taste-related molecules in the oral and extra-oral tissues.
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Affiliation(s)
- Kurumi Yamamoto
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
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99
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Breza JM, Contreras RJ. Acetic acid modulates spike rate and spike latency to salt in peripheral gustatory neurons of rats. J Neurophysiol 2012; 108:2405-18. [PMID: 22896718 DOI: 10.1152/jn.00114.2012] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Sour and salt taste interactions are not well understood in the peripheral gustatory system. Therefore, we investigated the interaction of acetic acid and NaCl on taste processing by rat chorda tympani neurons. We recorded multi-unit responses from the severed chorda tympani nerve (CT) and single-cell responses from intact narrowly tuned and broadly tuned salt-sensitive neurons in the geniculate ganglion simultaneously with stimulus-evoked summated potentials to signal when the stimulus contacted the lingual epithelium. Artificial saliva served as the rinse and solvent for all stimuli [0.3 M NH(4)Cl, 0.5 M sucrose, 0.1 M NaCl, 0.01 M citric acid, 0.02 M quinine hydrochloride (QHCl), 0.1 M KCl, 0.003-0.1 M acetic acid, and 0.003-0.1 M acetic acid mixed with 0.1 M NaCl]. We used benzamil to assess NaCl responses mediated by the epithelial sodium channel (ENaC). The CT nerve responses to acetic acid/NaCl mixtures were less than those predicted by summing the component responses. Single-unit analyses revealed that acetic acid activated acid-generalist neurons exclusively in a concentration-dependent manner: increasing acid concentration increased response frequency and decreased response latency in a parallel fashion. Acetic acid suppressed NaCl responses in ENaC-dependent NaCl-specialist neurons, whereas acetic acid-NaCl mixtures were additive in acid-generalist neurons. These data suggest that acetic acid attenuates sodium responses in ENaC-expressing-taste cells in contact with NaCl-specialist neurons, whereas acetic acid-NaCl mixtures activate distinct receptor/cellular mechanisms on taste cells in contact with acid-generalist neurons. We speculate that NaCl-specialist neurons are in contact with type I cells, whereas acid-generalist neurons are in contact with type III cells in fungiform taste buds.
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Affiliation(s)
- Joseph M Breza
- Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, Florida 32306-4301, USA
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100
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Romanov RA, Rogachevskaja OA, Bystrova MF, Kolesnikov SS. Electrical excitability of taste cells. Mechanisms and possible physiological significance. BIOCHEMISTRY MOSCOW SUPPLEMENT SERIES A-MEMBRANE AND CELL BIOLOGY 2012. [DOI: 10.1134/s1990747812010126] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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