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Jalševac F, Terra X, Rodríguez-Gallego E, Beltran-Debón R, Blay MT, Pinent M, Ardévol A. The Hidden One: What We Know About Bitter Taste Receptor 39. Front Endocrinol (Lausanne) 2022; 13:854718. [PMID: 35345470 PMCID: PMC8957101 DOI: 10.3389/fendo.2022.854718] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 02/04/2022] [Indexed: 12/21/2022] Open
Abstract
Over thousands of years of evolution, animals have developed many ways to protect themselves. One of the most protective ways to avoid disease is to prevent the absorption of harmful components. This protective function is a basic role of bitter taste receptors (TAS2Rs), a G protein-coupled receptor family, whose presence in extraoral tissues has intrigued many researchers. In humans, there are 25 TAS2Rs, and although we know a great deal about some of them, others are still shrouded in mystery. One in this latter category is bitter taste receptor 39 (TAS2R39). Besides the oral cavity, it has also been found in the gastrointestinal tract and the respiratory, nervous and reproductive systems. TAS2R39 is a relatively non-selective receptor, which means that it can be activated by a range of mostly plant-derived compounds such as theaflavins, catechins and isoflavones. On the other hand, few antagonists for this receptor are available, since only some flavones have antagonistic properties (all of them detailed in the document). The primary role of TAS2R39 is to sense the bitter components of food and protect the organism from harmful compounds. There is also some indication that this bitter taste receptor regulates enterohormones and in turn, regulates food intake. In the respiratory system, it may be involved in the congestion process of allergic rhinitis and may stimulate inflammatory cytokines. However, more thorough research is needed to determine the precise role of TAS2R39 in these and other tissues.
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von Molitor E, Riedel K, Krohn M, Hafner M, Rudolf R, Cesetti T. Sweet Taste Is Complex: Signaling Cascades and Circuits Involved in Sweet Sensation. Front Hum Neurosci 2021; 15:667709. [PMID: 34239428 PMCID: PMC8258107 DOI: 10.3389/fnhum.2021.667709] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Accepted: 05/20/2021] [Indexed: 12/13/2022] Open
Abstract
Sweetness is the preferred taste of humans and many animals, likely because sugars are a primary source of energy. In many mammals, sweet compounds are sensed in the tongue by the gustatory organ, the taste buds. Here, a group of taste bud cells expresses a canonical sweet taste receptor, whose activation induces Ca2+ rise, cell depolarization and ATP release to communicate with afferent gustatory nerves. The discovery of the sweet taste receptor, 20 years ago, was a milestone in the understanding of sweet signal transduction and is described here from a historical perspective. Our review briefly summarizes the major findings of the canonical sweet taste pathway, and then focuses on molecular details, about the related downstream signaling, that are still elusive or have been neglected. In this context, we discuss evidence supporting the existence of an alternative pathway, independent of the sweet taste receptor, to sense sugars and its proposed role in glucose homeostasis. Further, given that sweet taste receptor expression has been reported in many other organs, the physiological role of these extraoral receptors is addressed. Finally, and along these lines, we expand on the multiple direct and indirect effects of sugars on the brain. In summary, the review tries to stimulate a comprehensive understanding of how sweet compounds signal to the brain upon taste bud cells activation, and how this gustatory process is integrated with gastro-intestinal sugar sensing to create a hedonic and metabolic representation of sugars, which finally drives our behavior. Understanding of this is indeed a crucial step in developing new strategies to prevent obesity and associated diseases.
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Affiliation(s)
- Elena von Molitor
- Institute of Molecular and Cell Biology, Hochschule Mannheim, Mannheim, Germany
| | | | | | - Mathias Hafner
- Institute of Molecular and Cell Biology, Hochschule Mannheim, Mannheim, Germany
| | - Rüdiger Rudolf
- Institute of Molecular and Cell Biology, Hochschule Mannheim, Mannheim, Germany.,Interdisciplinary Center for Neurosciences, Heidelberg University, Heidelberg, Germany
| | - Tiziana Cesetti
- Institute of Molecular and Cell Biology, Hochschule Mannheim, Mannheim, Germany
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Sell EA, Ortiz-Carpena JF, Herbert DR, Cohen NA. Tuft cells in the pathogenesis of chronic rhinosinusitis with nasal polyps and asthma. Ann Allergy Asthma Immunol 2020; 126:143-151. [PMID: 33122124 DOI: 10.1016/j.anai.2020.10.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 10/10/2020] [Accepted: 10/22/2020] [Indexed: 02/07/2023]
Abstract
OBJECTIVE To review the latest discoveries regarding the role of tuft cells in the pathogenesis of chronic rhinosinusitis (CRS) with nasal polyposis and asthma. DATA SOURCES Reviews and primary research manuscripts were identified from PubMed, Google, and bioRxiv using the search words airway epithelium, nasal polyposis, CRS or asthma and chemoreceptor cell, solitary chemosensory cell, brush cell, microvillus cell, and tuft cell. STUDY SELECTIONS Studies were selected on the basis of novelty and likely relevance to the functions of tuft cells in chronic inflammatory diseases in the upper and lower airways. RESULTS Tuft cells coordinate a variety of immune responses throughout the body. After the activation of bitter-taste receptors, tuft cells coordinate the secretion of antimicrobial products by adjacent epithelial cells and initiate the calcium-dependent release of acetylcholine resulting in neurogenic inflammation, including mast cell degranulation and plasma extravasation. Tuft cells are also the dominant source of interleukin-25 and a significant source of cysteinyl leukotrienes that play a role in initiating inflammatory processes in the airway. Tuft cells have also been found to seem de novo in the distal airway after a viral infection, implicating these cells in dysplastic remodeling in the distal lung in the pathogenesis of asthma. CONCLUSION Tuft cells bridge innate and adaptive immunes responses and play an upstream role in initiating type 2 inflammation in the upper and possibly the lower airway. The role of tuft cells in respiratory pathophysiology must be further investigated, because tuft cells are putative high-value therapeutic targets for novel therapeutics in CRS with nasal polyps and asthma.
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Affiliation(s)
- Elizabeth A Sell
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.
| | - Jorge F Ortiz-Carpena
- Department of Pathobiology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, Pennsylvania
| | - De'Broski R Herbert
- Department of Pathobiology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, Pennsylvania
| | - Noam A Cohen
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; Division of Rhinology, Department of Otorhinolaryngology-Head and Neck Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; Corporal Michael J. Crescenz Veterans Administration Medical Center, Veterans Health Administration, United States Department of Veteran Affairs, Philadelphia, Pennsylvania; Monell Chemical Senses Center, Philadelphia, Pennsylvania
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Huang SH, de Almeida JR, Watson E, Glogauer M, Xu W, Keshavarzi S, O'Sullivan B, Ringash J, Hope A, Bayley A, Bratman SV, Cho J, Giuliani M, Kim J, Waldron J, Spreafico A, Goldstein DP, Chepeha DB, Li T, Hosni A. Short-term and long-term unstimulated saliva flow following unilateral vs bilateral radiotherapy for oropharyngeal carcinoma. Head Neck 2020; 43:456-466. [PMID: 33058305 DOI: 10.1002/hed.26496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 08/31/2020] [Accepted: 09/22/2020] [Indexed: 11/07/2022] Open
Abstract
BACKGROUND We aimed to compare unstimulated saliva flow using 3-minute modified Schirmer test (MST) following bilateral vs unilateral radiotherapy (RT) in oropharyngeal carcinoma (OPC). METHODS We reviewed OPC patients treated with definitive intensity-modulated radiation therapy (IMRT) between 2011 and 2017. MST was measured at baseline, 1-/6-/12-/24-month post-RT. MST values were compared between bilateral-RT vs unilateral-RT groups. Multivariable logistic regression analysis (MVA) identified predictors of hyposalivation (MST < 25 mm). RESULTS Total 498 bilateral-RT and 36 unilateral-RT patients were eligible. The MST values at 1-/6-/12-/24-month post-RT were all significantly reduced from baseline for the entire cohort. Baseline unilateral-RT and bilateral-RT MST values (in mm) were similar (P = .2), but much higher for unilateral-RT 1-month (mean: 19.1 vs 13.0, P = .03), 6-month (20.5 vs 9.3, P < .001), 12-month (20.1 vs 11.9, P < .01), and 24-month post-RT (22.2 vs 13.9, P = .04). MVA confirmed that unilateral RT reduced the likelihood of hyposalivation vs bilateral RT (OR 2.36, P = .006). CONCLUSION Unilateral RT reduces unstimulated salivary flow in OPC patients.
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Affiliation(s)
- Shao Hui Huang
- Department of Radiation Oncology, Princess Margaret Cancer Centre/University of Toronto, Toronto, Ontario, Canada.,Department of Otolaryngology-Head & Neck Surgery/Surgical Oncology, Princess Margaret Cancer Centre/University of Toronto, Toronto, Ontario, Canada
| | - John R de Almeida
- Department of Otolaryngology-Head & Neck Surgery/Surgical Oncology, Princess Margaret Cancer Centre/University of Toronto, Toronto, Ontario, Canada
| | - Erin Watson
- Department of Dental Oncology and Maxillofacial Prosthetics, Princess Margaret Cancer Centre/University of Toronto, Toronto, Ontario, Canada
| | - Michael Glogauer
- Department of Dental Oncology and Maxillofacial Prosthetics, Princess Margaret Cancer Centre/University of Toronto, Toronto, Ontario, Canada
| | - Wei Xu
- Department of Biostatistics, Princess Margaret Cancer Centre / University of Toronto, Toronto, Ontario, Canada
| | - Sareh Keshavarzi
- Department of Biostatistics, Princess Margaret Cancer Centre / University of Toronto, Toronto, Ontario, Canada
| | - Brian O'Sullivan
- Department of Radiation Oncology, Princess Margaret Cancer Centre/University of Toronto, Toronto, Ontario, Canada.,Department of Otolaryngology-Head & Neck Surgery/Surgical Oncology, Princess Margaret Cancer Centre/University of Toronto, Toronto, Ontario, Canada
| | - Jolie Ringash
- Department of Radiation Oncology, Princess Margaret Cancer Centre/University of Toronto, Toronto, Ontario, Canada.,Department of Otolaryngology-Head & Neck Surgery/Surgical Oncology, Princess Margaret Cancer Centre/University of Toronto, Toronto, Ontario, Canada
| | - Andrew Hope
- Department of Radiation Oncology, Princess Margaret Cancer Centre/University of Toronto, Toronto, Ontario, Canada
| | - Andrew Bayley
- Department of Radiation Oncology, Princess Margaret Cancer Centre/University of Toronto, Toronto, Ontario, Canada
| | - Scott V Bratman
- Department of Radiation Oncology, Princess Margaret Cancer Centre/University of Toronto, Toronto, Ontario, Canada
| | - John Cho
- Department of Radiation Oncology, Princess Margaret Cancer Centre/University of Toronto, Toronto, Ontario, Canada
| | - Meredith Giuliani
- Department of Radiation Oncology, Princess Margaret Cancer Centre/University of Toronto, Toronto, Ontario, Canada
| | - John Kim
- Department of Radiation Oncology, Princess Margaret Cancer Centre/University of Toronto, Toronto, Ontario, Canada
| | - John Waldron
- Department of Radiation Oncology, Princess Margaret Cancer Centre/University of Toronto, Toronto, Ontario, Canada.,Department of Otolaryngology-Head & Neck Surgery/Surgical Oncology, Princess Margaret Cancer Centre/University of Toronto, Toronto, Ontario, Canada
| | - Anna Spreafico
- Department of Medical Oncology, Princess Margaret Cancer Centre/University of Toronto, Toronto, Ontario, Canada
| | - David P Goldstein
- Department of Otolaryngology-Head & Neck Surgery/Surgical Oncology, Princess Margaret Cancer Centre/University of Toronto, Toronto, Ontario, Canada
| | - Douglas B Chepeha
- Department of Otolaryngology-Head & Neck Surgery/Surgical Oncology, Princess Margaret Cancer Centre/University of Toronto, Toronto, Ontario, Canada
| | - Tong Li
- Department of Radiation Oncology, Princess Margaret Cancer Centre/University of Toronto, Toronto, Ontario, Canada
| | - Ali Hosni
- Department of Radiation Oncology, Princess Margaret Cancer Centre/University of Toronto, Toronto, Ontario, Canada
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An alternative pathway for sweet sensation: possible mechanisms and physiological relevance. Pflugers Arch 2020; 472:1667-1691. [PMID: 33030576 DOI: 10.1007/s00424-020-02467-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 09/14/2020] [Accepted: 09/23/2020] [Indexed: 12/12/2022]
Abstract
Sweet substances are detected by taste-bud cells upon binding to the sweet-taste receptor, a T1R2/T1R3 heterodimeric G protein-coupled receptor. In addition, experiments with mouse models lacking the sweet-taste receptor or its downstream signaling components led to the proposal of a parallel "alternative pathway" that may serve as metabolic sensor and energy regulator. Indeed, these mice showed residual nerve responses and behavioral attraction to sugars and oligosaccharides but not to artificial sweeteners. In analogy to pancreatic β cells, such alternative mechanism, to sense glucose in sweet-sensitive taste cells, might involve glucose transporters and KATP channels. Their activation may induce depolarization-dependent Ca2+ signals and release of GLP-1, which binds to its receptors on intragemmal nerve fibers. Via unknown neuronal and/or endocrine mechanisms, this pathway may contribute to both, behavioral attraction and/or induction of cephalic-phase insulin release upon oral sweet stimulation. Here, we critically review the evidence for a parallel sweet-sensitive pathway, involved signaling mechanisms, neural processing, interactions with endocrine hormonal mechanisms, and its sensitivity to different stimuli. Finally, we propose its physiological role in detecting the energy content of food and preparing for digestion.
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Gao S, Liu S, Yao J, Zhou T, Li N, Li Q, Dunham R, Liu Z. Taste receptors and gustatory associated G proteins in channel catfish, Ictalurus punctatus. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY D-GENOMICS & PROTEOMICS 2016; 21:1-9. [PMID: 27806254 DOI: 10.1016/j.cbd.2016.10.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Revised: 10/17/2016] [Accepted: 10/19/2016] [Indexed: 11/18/2022]
Abstract
Taste sensation plays a pivotal role in nutrient identification and acquisition. This is particularly true for channel catfish (Ictalurus punctatus) that live in turbid waters with limited visibility. This biological process is mainly mediated by taste receptors expressed in taste buds that are distributed in several organs and tissues, including the barbels and skin. In the present study, we identified a complete repertoire of taste receptor and gustatory associated G protein genes in the channel catfish genome. A total of eight taste receptor genes were identified, including five type I and three type II taste receptor genes. Their genomic locations, phylogenetic relations, orthologies and expression were determined. Phylogenetic and collinear analyses provided understanding of the evolution dynamics of this gene family. Furthermore, the motif and dN/dS analyses indicated that selection pressures of different degrees were imposed on these receptors. Additionally, four genes of gustatory associated G proteins were also identified. It was indicated that expression patterns of catfish taste receptors and gustatory associated G proteins across organs mirror the distribution of taste buds across organs. Finally, the expression comparison between catfish and zebrafish organs provided evidence of potential roles of catfish skin and gill involved in taste sensation.
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Affiliation(s)
- Sen Gao
- The Fish Molecular Genetics and Biotechnology Laboratory, Aquatic Genomics Unit, School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, Auburn, AL 36849, USA
| | - Shikai Liu
- The Fish Molecular Genetics and Biotechnology Laboratory, Aquatic Genomics Unit, School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, Auburn, AL 36849, USA
| | - Jun Yao
- The Fish Molecular Genetics and Biotechnology Laboratory, Aquatic Genomics Unit, School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, Auburn, AL 36849, USA
| | - Tao Zhou
- The Fish Molecular Genetics and Biotechnology Laboratory, Aquatic Genomics Unit, School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, Auburn, AL 36849, USA
| | - Ning Li
- The Fish Molecular Genetics and Biotechnology Laboratory, Aquatic Genomics Unit, School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, Auburn, AL 36849, USA
| | - Qi Li
- Key Laboratory of Mariculture of the Ministry of Education, Ocean University of China, Qingdao, China
| | - Rex Dunham
- The Fish Molecular Genetics and Biotechnology Laboratory, Aquatic Genomics Unit, School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, Auburn, AL 36849, USA
| | - Zhanjiang Liu
- The Fish Molecular Genetics and Biotechnology Laboratory, Aquatic Genomics Unit, School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, Auburn, AL 36849, USA.
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7
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Pinna R, Campus G, Cumbo E, Mura I, Milia E. Xerostomia induced by radiotherapy: an overview of the physiopathology, clinical evidence, and management of the oral damage. Ther Clin Risk Manag 2015; 11:171-88. [PMID: 25691810 PMCID: PMC4325830 DOI: 10.2147/tcrm.s70652] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND The irradiation of head and neck cancer (HNC) often causes damage to the salivary glands. The resulting salivary gland hypofunction and xerostomia seriously reduce the patient's quality of life. PURPOSE To analyze the literature of actual management strategies for radiation-induced hypofunction and xerostomia in HNC patients. METHODS MEDLINE/PubMed and the Cochrane Library databases were electronically evaluated for articles published from January 1, 1970, to June 30, 2013. Two reviewers independently screened and included papers according to the predefined selection criteria. RESULTS Sixty-one articles met the inclusion criteria. The systematic review of the literature suggests that the most suitable methods for managing the clinical and pathophysiological consequences of HNC radiotherapy might be the pharmacological approach, for example, through the use of cholinergic agonists when residual secretory capacity is still present, and the use of salivary substitutes. In addition, a modified diet and the patient's motivation to enhance oral hygiene can lead to a significant improvement. CONCLUSION Radiation-induced xerostomia could be considered a multifactorial disease. It could depend on the type of cancer treatment and the cumulative radiation dose to the gland tissue. A preventive approach and the correct treatment of the particular radiotherapeutic patient can help to improve the condition of xerostomia.
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Affiliation(s)
- Roberto Pinna
- Department of Biomedical Science, University of Sassari, Sassari, Italy
| | - Guglielmo Campus
- Department of Surgery, Microsurgery and Medicine, University of Sassari, Sassari, Italy
| | - Enzo Cumbo
- Department of Dental Science, University of Palermo, Palermo, Italy
| | - Ida Mura
- Department of Biomedical Science, University of Sassari, Sassari, Italy
| | - Egle Milia
- Department of Surgery, Microsurgery and Medicine, University of Sassari, Sassari, Italy
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8
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Cygankiewicz AI, Maslowska A, Krajewska WM. Molecular Basis of Taste Sense: Involvement of GPCR Receptors. Crit Rev Food Sci Nutr 2013; 54:771-80. [DOI: 10.1080/10408398.2011.606929] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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9
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Chen ML, Liu SS, Zhang GH, Quan Y, Zhan YH, Gu TY, Qin YM, Deng SP. Effects of early intraoral acesulfame-K stimulation to mice on the adult's sweet preference and the expression of α-gustducin in fungiform papilla. Chem Senses 2013; 38:447-55. [PMID: 23537561 DOI: 10.1093/chemse/bjt001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Exposure to artificial sweetener acesulfame-K (AK) at early development stages may influence the adult sweet preference and the periphery gustatory system. We observed that the intraoral AK stimulation to mice from postnatal day 4 (P4) to weaning decreased the preference thresholds for AK and sucrose solutions in adulthood, with the preference pattern unchanged. The preference scores were increased in the exposure group significantly when compared with the control group at a range of concentrations for AK or sucrose solution. Meanwhile, more α-Gustducin-labeled fungiform taste buds and cells in a single taste bud were induced from week 7 by the early intraoral AK stimulation. However, the growth in the number of α-Gustducin-positive taste bud or positive cell number per taste bud occurred only in the anterior region, the rostral 1-mm part, but not in the intermediate region, the caudal 4-mm part, of the anterior two-third of the tongue containing fungiform papillae. This work extends our previous observations and provides new information about the developmental and regional expression pattern of α-Gustducin in mouse fungiform taste bud under early AK-stimulated conditions.
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Affiliation(s)
- Meng-Ling Chen
- Sensory Science Laboratory, School of Bioscience and Food Engineering, Changshu Institute of Technology, Changshu 215500, PR China.
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Fushan AA, Simons CT, Slack JP, Drayna D. Association between common variation in genes encoding sweet taste signaling components and human sucrose perception. Chem Senses 2010; 35:579-92. [PMID: 20660057 DOI: 10.1093/chemse/bjq063] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Variation in taste perception of different chemical substances is a well-known phenomenon in both humans and animals. Recent advances in the understanding of sweet taste signaling have identified a number of proteins involved in this signal transduction. We evaluated the hypothesis that sequence variations occurring in genes encoding taste signaling molecules can influence sweet taste perception in humans. Our population consisted of unrelated individuals (n = 160) of Caucasian, African-American, and Asian descent. Threshold and suprathreshold sensitivities of participants for sucrose were estimated using a sorting test and signal detection analysis that produced cumulative R-index area under the curve (AUC) scores. Genetic association analysis revealed significant correlation of sucrose AUC scores with genetic variation occurring in the GNAT3 gene (single point P = 10(-3) to 10(-4)), which encodes the taste-specific G(alpha) protein subunit gustducin. Subsequent sequencing identified additional GNAT3 variations having significant association with sucrose AUC scores. Collectively, GNAT3 polymorphisms explain 13% of the variation in sucrose perception. Our findings underscore the importance of common genetic variants influencing human taste perception.
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Affiliation(s)
- Alexey A Fushan
- National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Rockville, MD 20850, USA
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11
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Hass N, Schwarzenbacher K, Breer H. A cluster of gustducin-expressing cells in the mouse stomach associated with two distinct populations of enteroendocrine cells. Histochem Cell Biol 2007; 128:457-71. [PMID: 17874119 DOI: 10.1007/s00418-007-0325-3] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/31/2007] [Indexed: 12/22/2022]
Abstract
In the gastrointestinal (GI) tract, a variety of digestive processes are continually adapted to the changing composition of ingested foods, which requires a precise chemosensory monitoring of luminal contents. Gustducin-expressing brush cells scattered throughout the GI mucosa are considered candidate sensory cells for accomplishing this task. In this study, we have investigated a large cluster of gustducin-positive cells which is located exactly at the boundary between the fundic and the oxyntic mucosa of the mouse stomach, at the so-called "limiting ridge". In close association with the candidate chemosensory cluster, we found two populations of enteroendocrine cells: one population containing the satiety regulating hormone ghrelin, the other population comprising serotonin-secreting enterochromaffin cells. The particular arrangement of gustducin-expressing cells and enteroendocrine cells at the limiting ridge suggests a direct interplay between these cell types with immediate implications, not only for digestive processes in the stomach, but also for parameters controlling the satiety status.
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Affiliation(s)
- Nicole Hass
- University of Hohenheim, Institute of Physiology, Garbenstrasse 30, 70599, Stuttgart, Germany
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12
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Keast RSJ, Breslin PAS. Modifying the bitterness of selected oral pharmaceuticals with cation and anion series of salts. Pharm Res 2002; 19:1019-26. [PMID: 12180534 DOI: 10.1023/a:1016474607993] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
PURPOSE NaCl has proven to be an effective bitterness inhibitor, but the reason remains unclear. The purpose of this study was to examine the influence of a variety of cations and anions on the bitterness of selected oral pharmaceuticals and bitter taste stimuli: pseudoephedrine, ranitidine, acetaminophen, quinine, and urea. METHOD Human psychophysical taste evaluation using a whole mouth exposure procedure was used. RESULTS The cations (all associated with the acetate anion) inhibited bitterness when mixed with pharmaceutical solutions to varying degrees. The sodium cation significantly (P < 0.003) inhibited bitterness of the pharmaceuticals more than the other cations. The anions (all associated with the sodium cation) also inhibited bitterness to varying degrees. With the exception of salicylate, the glutamate and adenosine monophosphate anions significantly (P < 0.001) inhibited bitterness of the pharmaceuticals more than the other anions. Also, there were several specific inhibitory interactions between ammonium, sodium and salicylate and certain pharmaceuticals. CONCLUSIONS We conclude that sodium was the most successful cation and glutamate and AMP were the most successful anions at inhibiting bitterness. Structure forming and breaking properties of ions, as predicted by the Hofmeister series. and other physical-chemical ion properties failed to significantly predict bitterness inhibition.
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Affiliation(s)
- Russell S J Keast
- Monell Chemical Senses Center, Philadelphia, Pennsylvania 19104, USA.
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Rats fail to discriminate quinine from denatonium: implications for the neural coding of bitter-tasting compounds. J Neurosci 2002. [PMID: 11880524 DOI: 10.1523/jneurosci.22-05-01937.2002] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Recent molecular findings indicate that many different G-protein-coupled taste receptors that bind with "bitter-tasting" ligands are coexpressed in single taste receptor cells in taste buds, leading to the prediction that mammals can respond behaviorally to structurally diverse "bitter" tastants but cannot discriminate among them. However, recent in situ calcium-imaging findings imply that rat taste receptor cells are more narrowly tuned to respond to bitter-tasting compounds than had been predicted from molecular findings, suggesting that these animals can discriminate among these chemicals. Using an operant conditioning paradigm, we demonstrated that rats cannot discriminate between two structurally dissimilar bitter compounds, quinine hydrochloride and denatonium benzoate, despite the fact that these tastants are thought to stimulate different taste receptor cells. These rats were nonetheless able to show concentration-dependent avoidance responses to both compounds in brief-access tests and to discriminate among other taste stimuli, including quinine versus KCl, denatonium versus KCl, and NaCl versus KCl. Importantly, the concentrations were varied in the discrimination tests to render intensity an irrelevant cue. We conclude that denatonium and quinine produce a unitary taste sensation, leaving open the likely possibility that other compounds fall into this class. Although a broader array of compounds needs to be tested, our findings lend support to the hypothesis that there is only one qualitative type of bitterness. These results also highlight the need to confirm predictions about the downstream properties of the gustatory system, or any sensory system, based on upstream molecular and biophysical events.
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14
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Affiliation(s)
- Robert F Margolskee
- Howard Hughes Medical Institute, Department of Physiology and Biophysics, Mount Sinai School of Medicine, New York, New York 10029, USA.
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15
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Abstract
Food choices and eating habits are largely influenced by how foods taste. Without being the dominant taste sensation, bitter taste contributes to the complexity and enjoyment of beverages and foods. Compounds that are perceived as bitter do not share a similar chemical structure. In addition to peptides and salts, bitter compounds in foods may include plant-derived phenols and polyphenols, flavonoids, catechins, and caffeine. Recent studies have shown that humans possess a multitude of bitter taste receptors and that the transduction of bitter taste may differ between one compound and another. Studies of mixture interactions suggest further that bitter compounds suppress or enhance sweet and sour tastes and interact with volatile flavor molecules. Caffeine, a natural ingredient of tea, coffee, and chocolate, has a unique flavor profile. Used as a flavoring agent, it enhances the sensory appeal of beverages. Research developments on the genetics and perception of bitter taste add to our understanding of the role of bitterness in relation to food preference.
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Affiliation(s)
- A Drewnowski
- Nutritional Sciences Program, University of Washington, Seattle 98195-3410, USA
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16
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Yan W, Sunavala G, Rosenzweig S, Dasso M, Brand JG, Spielman AI. Bitter taste transduced by PLC-beta(2)-dependent rise in IP(3) and alpha-gustducin-dependent fall in cyclic nucleotides. Am J Physiol Cell Physiol 2001; 280:C742-51. [PMID: 11245589 DOI: 10.1152/ajpcell.2001.280.4.c742] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Current evidence points to the existence of multiple processes for bitter taste transduction. Previous work demonstrated involvement of the polyphosphoinositide system and an alpha-gustducin (Galpha(gust))-mediated stimulation of phosphodiesterase in bitter taste transduction. Additionally, a taste-enriched G protein gamma-subunit, Ggamma(13), colocalizes with Galpha(gust) and mediates the denatonium-stimulated production of inositol 1,4,5-trisphosphate (IP(3)). Using quench-flow techniques, we show here that the bitter stimuli, denatonium and strychnine, induce rapid (50-100 ms) and transient reductions in cAMP and cGMP and increases in IP(3) in murine taste tissue. This decrease of cyclic nucleotides is inhibited by Galpha(gust) antibodies, whereas the increase in IP(3) is not affected by antibodies to Galpha(gust). IP(3) production is inhibited by antibodies specific to phospholipase C-beta(2) (PLC-beta(2)), a PLC isoform known to be activated by Gbetagamma-subunits. Antibodies to PLC-beta(3) or to PLC-beta(4) were without effect. These data suggest a transduction mechanism for bitter taste involving the rapid and transient metabolism of dual second messenger systems, both mediated through a taste cell G protein, likely composed of Galpha(gust)/beta/gamma(13), with both systems being simultaneously activated in the same bitter-sensitive taste receptor cell.
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Affiliation(s)
- W Yan
- Department of Basic Science and Craniofacial Biology, Division of Biological Science, Medicine, and Surgery, New York University College of Dentistry, 345 E. 24th St., New York, NY 10010, USA
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Abstract
Taste receptor cells use a variety of mechanisms to transduce chemical information into cellular signals. Seven-transmembrane-helix receptors initiate signaling cascades by coupling to G proteins, effector enzymes, second messengers and ion channels. Apical ion channels pass ions, leading to depolarizing and/or hyperpolarizing responses. New insights into the mechanisms of taste sensation have been gained from molecular cloning of the transduction elements, biochemical elucidation of the transduction pathways, and electrophysiological analysis of the function of taste cell ion channels.
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Affiliation(s)
- T A Gilbertson
- Department of Biology, Utah State University, Logan 84322-5305, USA.
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18
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Abstract
Taste receptor cells respond to gustatory stimuli using a complex arrangement of receptor molecules, signaling cascades, and ion channels. When stimulated, these cells produce action potentials that result in the release of neurotransmitter onto an afferent nerve fiber that in turn relays the identity and intensity of the gustatory stimuli to the brain. A variety of mechanisms are used in transducing the four primary tastes. Direct interaction of the stimuli with ion channels appears to be of particular importance in transducing stimuli reported as salty or sour, whereas the second messenger systems cyclic AMP and inositol trisphosphate are important in transducing bitter and sweet stimuli. In addition to the four basic tastes, specific mechanisms exist for the amino acid glutamate, which is sometimes termed the fifth primary taste, and for fatty acids, a so-called nonconventional taste stimulus. The emerging picture is that not only do individual taste qualities use more than one mechanism, but multiple pathways are available for individual tastants as well.
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Affiliation(s)
- M S Herness
- College of Dentistry, Ohio State University, Columbus 43210-1241, USA.
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