scholarly journals Biophysical and functional characterization of the human TAS1R2 sweet taste receptor overexpressed in a HEK293S inducible cell line

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Christine Belloir ◽  
Marine Brulé ◽  
Lucie Tornier ◽  
Fabrice Neiers ◽  
Loïc Briand
Keyword(s):  
Cell Line ◽  
Molecular Mechanisms ◽  
Transmembrane Domain ◽  
Functional Characterization ◽  
Taste Receptor ◽  
Spectroscopic Studies ◽  
Sweet Taste ◽  
Taste Perception ◽  
Size Exclusion ◽  
High Potency

AbstractSweet taste perception is mediated by a heterodimeric receptor formed by the assembly of the TAS1R2 and TAS1R3 subunits. TAS1R2 and TAS1R3 are class C G-protein-coupled receptors whose members share a common topology, including a large extracellular N-terminal domain (NTD) linked to a seven transmembrane domain (TMD) by a cysteine-rich domain. TAS1R2-NTD contains the primary binding site for sweet compounds, including natural sugars and high-potency sweeteners, whereas the TAS1R2-TMD has been shown to bind a limited number of sweet tasting compounds. To understand the molecular mechanisms governing receptor–ligand interactions, we overexpressed the human TAS1R2 (hTAS1R2) in a stable tetracycline-inducible HEK293S cell line and purified the detergent-solubilized receptor. Circular dichroism spectroscopic studies revealed that hTAS1R2 was properly folded with evidence of secondary structures. Using size exclusion chromatography coupled to light scattering, we found that the hTAS1R2 subunit is a dimer. Ligand binding properties were quantified by intrinsic tryptophan fluorescence. Due to technical limitations, natural sugars have not been tested. However, we showed that hTAS1R2 is capable of binding high potency sweeteners with Kd values that are in agreement with physiological detection. This study offers a new experimental strategy to identify new sweeteners or taste modulators that act on the hTAS1R2 and is a prerequisite for structural query and biophysical studies.

scholarly journals Transformation of postingestive glucose responses after deletion of sweet taste receptor subunits or gastric bypass surgery

2012 ◽  
Vol 303 (4) ◽  
pp. E464-E474 ◽  
Author(s):  
Maartje C. P. Geraedts ◽  
Tatsuyuki Takahashi ◽  
Stephan Vigues ◽  
Michele L. Markwardt ◽  
Andongfac Nkobena ◽  
...  
Keyword(s):  
Gastric Bypass ◽  
Glycemic Control ◽  
Large Intestine ◽  
Molecular Mechanisms ◽  
Hormone Secretion ◽  
Taste Receptor ◽  
Sweet Taste ◽  
Oral Glucose ◽  
Isolated Pancreatic Islets ◽  
Sweet Taste Receptor

The glucose-dependent secretion of the insulinotropic hormone glucagon-like peptide-1 (GLP-1) is a critical step in the regulation of glucose homeostasis. Two molecular mechanisms have separately been suggested as the primary mediator of intestinal glucose-stimulated GLP-1 secretion (GSGS): one is a metabotropic mechanism requiring the sweet taste receptor type 2 (T1R2) + type 3 (T1R3) while the second is a metabolic mechanism requiring ATP-sensitive K+(KATP) channels. By quantifying sugar-stimulated hormone secretion in receptor knockout mice and in rats receiving Roux-en-Y gastric bypass (RYGB), we found that both of these mechanisms contribute to GSGS; however, the mechanisms exhibit different selectivity, regulation, and localization. T1R3−/−mice showed impaired glucose and insulin homeostasis during an oral glucose challenge as well as slowed insulin granule exocytosis from isolated pancreatic islets. Glucose, fructose, and sucralose evoked GLP-1 secretion from T1R3+/+, but not T1R3−/−, ileum explants; this secretion was not mimicked by the KATPchannel blocker glibenclamide. T1R2−/−mice showed normal glycemic control and partial small intestine GSGS, suggesting that T1R3 can mediate GSGS without T1R2. Robust GSGS that was KATPchannel-dependent and glucose-specific emerged in the large intestine of T1R3−/−mice and RYGB rats in association with elevated fecal carbohydrate throughout the distal gut. Our results demonstrate that the small and large intestines utilize distinct mechanisms for GSGS and suggest novel large intestine targets that could mimic the improved glycemic control seen after RYGB.

Taste Perception and Cerebral Activity in the Human Gustatory Cortex Induced by Glucose, Fructose, and Sucrose Solutions

2019 ◽  
Vol 44 (7) ◽  
pp. 435-447 ◽  
Author(s):  
Thomas Mouillot ◽  
Sophie Barthet ◽  
Lucie Janin ◽  
Camille Creteau ◽  
Hervé Devilliers ◽  
...  
Keyword(s):  
Taste Receptor ◽  
Sweet Taste ◽  
Molar Concentration ◽  
Cortical Activation ◽  
Taste Perception ◽  
Gustatory Cortex ◽  
Intensity Perception ◽  
Sucrose Solutions ◽  
Significant Difference ◽  
Sweetness Intensity

Abstract Glucose, fructose, and sucrose are important carbohydrates in Western diets with particular sweetness intensity and metabolisms. No study has compared their cerebral detection and their taste perception. Gustatory evoked potentials (GEPs), taste detection thresholds, intensity perception, and pleasantness were compared in response to glucose, fructose, and sucrose solutions at similar sweetness intensities and at identical molar concentrations. Twenty-three healthy subjects were randomly stimulated with 3 solutions of similar sweetness intensity (0.75 M of glucose, 0.47 M of fructose and 0.29 M of sucrose – sit. A), and with an identical molar concentration (0.29 M – sit. B). GEPs were recorded at gustatory cortex areas. Intensity perception and hedonic values of each solution were evaluated as were gustatory thresholds of the solutions. No significant difference was observed concerning the GEP characteristics of the solutions according to their sweetness intensities (sit. A) or their molar concentration (sit. B). In sit. A, the 3 solutions were perceived to have similar intensities and induced similar hedonic sensations. In sit. B, the glucose solution was perceived to be less intense and pleasant than the fructose and the sucrose solutions (P < 0.001) and the fructose solution was perceived to be less intense and pleasant than the sucrose (P < 0.001). Since GEP recordings were similar for glucose, fructose, and sucrose solutions whatever the concentrations, activation of same taste receptor induces similar cortical activation, even when the solutions were perceived differently. Sweet taste perception seems to be encoded by a complex chemical cerebral neuronal network.

scholarly journals Molecular mechanisms of taste transduction

2002 ◽  
Vol 74 (7) ◽  
pp. 1125-1133 ◽  
Author(s):  
Robert F. Margolskee
Keyword(s):  
Ion Channels ◽  
Molecular Cloning ◽  
G Proteins ◽  
Molecular Mechanisms ◽  
Transmembrane Helix ◽  
Taste Receptor ◽  
Sweet Taste ◽  
Chemical Diversity ◽  
Chemical Information ◽  
Taste Transduction

Taste transduction is a specialized form of signal transduction by which taste receptor cells (TRCs) encode at the cellular level information about chemical substances encountered in the oral environment (so-called tastants). Bitter and sweet taste transduction pathways convert chemical information into a cellular second messenger code utilizing cyclic nucleotides, inositol trisphosphate, and/or diacyl glycerol. These messengers are components of signaling cascades that lead to TRC depolarization and Ca++ release. Bitter and sweet taste transduction pathways typically utilize taste-specific or taste-selective seven transmembrane-helix receptors, G proteins, effector enzymes, second messengers, and ion channels. The structural and chemical diversity of tastants has led to the need for multiple transduction mechanisms. Through molecular cloning and data mining, many of the receptors, G proteins, and effector enzymes involved in transducing responses to bitter and sweet compounds are now known. New insights into taste transduction and taste coding underlying sweet and bitter taste qualities have been gained from molecular cloning of the transduction elements, biochemical elucidation of the transduction pathways, electrophysiological analysis of the function of taste cell ion channels, and behavioral analysis of transgenic and knockout models.

scholarly journals Persistent Epigenetic Reprogramming of Sweet Taste by Diet

2020 ◽  
Author(s):  
Anoumid Vaziri ◽  
Morteza Khabiri ◽  
Brendan T. Genaw ◽  
Christina E. May ◽  
Peter L. Freddolino ◽  
...  
Keyword(s):  
Neural Plasticity ◽  
Molecular Mechanisms ◽  
Control Diet ◽  
Sweet Taste ◽  
Taste Perception ◽  
Epigenetic Mechanism ◽  
High Sugar ◽  
Epigenetic Regulator ◽  
Transcriptional Changes ◽  
Gustatory Neurons

AbstractDiets rich in sugar, salt, and fat alter taste perception and food intake, leading to obesity and metabolic disorders, but the molecular mechanisms through which this occurs are unknown. Here we show that in response to a high sugar diet, the epigenetic regulator Polycomb Repressive Complex 2.1 (PRC2.1) persistently reprograms the sensory neurons of D. melanogaster flies to reduce sweet sensation and promote obesity. In animals fed high sugar, the binding of PRC2.1 to the chromatin of the sweet gustatory neurons is redistributed to repress a developmental transcriptional network that modulates the responsiveness of these cells to sweet stimuli, reducing sweet sensation. Importantly, half of these transcriptional changes persist despite returning the animals to a control diet, causing a permanent decrease in sweet taste. Our results uncover a new epigenetic mechanism that, in response to the dietary environment, regulates neural plasticity and feeding behavior to promote obesity.

scholarly journals New Insights on the Evolution of the Sweet Taste Receptor of Primates Adapted to Harsh Environments

Animals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2359
Author(s):  
Nur Aida Md Tamrin ◽  
Ramlah Zainudin ◽  
Yuzine Esa ◽  
Halimah Alias ◽  
Mohd Noor Mat Isa ◽  
...  
Keyword(s):  
Phylogenetic Trees ◽  
Environmental Changes ◽  
Receptor Gene ◽  
Taste Receptor ◽  
Sensory Information ◽  
Sweet Taste ◽  
Taste Perception ◽  
Sweet Taste Receptor ◽  
Dietary Preferences ◽  
Starting Point

Taste perception is an essential function that provides valuable dietary and sensory information, which is crucial for the survival of animals. Studies into the evolution of the sweet taste receptor gene (TAS1R2) are scarce, especially for Bornean endemic primates such as Nasalis larvatus (proboscis monkey), Pongo pygmaeus (Bornean orangutan), and Hylobates muelleri (Muller’s Bornean gibbon). Primates are the perfect taxa to study as they are diverse dietary feeders, comprising specialist folivores, frugivores, gummivores, herbivores, and omnivores. We constructed phylogenetic trees of the TAS1R2 gene for 20 species of anthropoid primates using four different methods (neighbor-joining, maximum parsimony, maximum-likelihood, and Bayesian) and also established the time divergence of the phylogeny. The phylogeny successfully separated the primates into their taxonomic groups as well as by their dietary preferences. Of note, the reviewed time of divergence estimation for the primate speciation pattern in this study was more recent than the previously published estimates. It is believed that this difference may be due to environmental changes, such as food scarcity and climate change, during the late Miocene epoch, which forced primates to change their dietary preferences. These findings provide a starting point for further investigation.

scholarly journals Conserved Residues Control the T1R3-Specific Allosteric Signaling Pathway of the Mammalian Sweet-Taste Receptor

2019 ◽  
Vol 44 (5) ◽  
pp. 303-310 ◽  
Author(s):  
Jean-Baptiste Chéron ◽  
Amanda Soohoo ◽  
Yi Wang ◽  
Jérôme Golebiowski ◽  
Serge Antonczak ◽  
...  
Keyword(s):  
Transmembrane Domain ◽  
Taste Receptor ◽  
Receptor Activation ◽  
Sweet Taste ◽  
Site Directed Mutagenesis ◽  
Activation Mechanism ◽  
Structural Basis ◽  
Directed Mutagenesis ◽  
Conserved Residues ◽  
Sweet Taste Receptor

Abstract Mammalian sensory systems detect sweet taste through the activation of a single heteromeric T1R2/T1R3 receptor belonging to class C G-protein-coupled receptors. Allosteric ligands are known to interact within the transmembrane domain, yet a complete view of receptor activation remains elusive. By combining site-directed mutagenesis with computational modeling, we investigate the structure and dynamics of the allosteric binding pocket of the T1R3 sweet-taste receptor in its apo form, and in the presence of an allosteric ligand, cyclamate. A novel positively charged residue at the extracellular loop 2 is shown to interact with the ligand. Molecular dynamics simulations capture significant differences in the behavior of a network of conserved residues with and without cyclamate, although they do not directly interact with the allosteric ligand. Structural models show that they adopt alternate conformations, associated with a conformational change in the transmembrane region. Site-directed mutagenesis confirms that these residues are unequivocally involved in the receptor function and the allosteric signaling mechanism of the sweet-taste receptor. Similar to a large portion of the transmembrane domain, they are highly conserved among mammals, suggesting an activation mechanism that is evolutionarily conserved. This work provides a structural basis for describing the dynamics of the receptor, and for the rational design of new sweet-taste modulators.

scholarly journals Persistent epigenetic reprogramming of sweet taste by diet

2020 ◽  
Vol 6 (46) ◽  
pp. eabc8492
Author(s):  
Anoumid Vaziri ◽  
Morteza Khabiri ◽  
Brendan T. Genaw ◽  
Christina E. May ◽  
Peter L. Freddolino ◽  
...  
Keyword(s):  
Neural Plasticity ◽  
Molecular Mechanisms ◽  
Control Diet ◽  
Sweet Taste ◽  
Taste Perception ◽  
Epigenetic Mechanism ◽  
High Sugar ◽  
Epigenetic Regulator ◽  
Transcriptional Changes ◽  
Gustatory Neurons

Diets rich in sugar, salt, and fat alter taste perception and food preference, contributing to obesity and metabolic disorders, but the molecular mechanisms through which this occurs are unknown. Here, we show that in response to a high sugar diet, the epigenetic regulator Polycomb Repressive Complex 2.1 (PRC2.1) persistently reprograms the sensory neurons of Drosophila melanogaster flies to reduce sweet sensation and promote obesity. In animals fed high sugar, the binding of PRC2.1 to the chromatin of the sweet gustatory neurons is redistributed to repress a developmental transcriptional network that modulates the responsiveness of these cells to sweet stimuli, reducing sweet sensation. Half of these transcriptional changes persist despite returning the animals to a control diet, causing a permanent decrease in sweet taste. Our results uncover a new epigenetic mechanism that, in response to the dietary environment, regulates neural plasticity and feeding behavior to promote obesity.

scholarly journals Sweeteners interacting with the transmembrane domain of the human sweet-taste receptor induce sweet-taste synergisms in binary mixtures

2012 ◽  
Vol 130 (3) ◽  
pp. 561-568 ◽  
Author(s):  
Satoshi Fujiwara ◽  
Takamasa Imada ◽  
Tomoya Nakagita ◽  
Shinji Okada ◽  
Takashi Nammoku ◽  
...  
Keyword(s):  
Binary Mixtures ◽  
Transmembrane Domain ◽  
Taste Receptor ◽  
Sweet Taste ◽  
Sweet Taste Receptor

scholarly journals Association between Salivary Leptin Levels and Taste Perception in Children

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Lénia Rodrigues ◽  
Rosa Espanca ◽  
Ana Rodrigues Costa ◽  
Célia Miguel Antunes ◽  
Clarinda Pomar ◽  
...  
Keyword(s):  
Bitter Taste ◽  
Taste Receptor ◽  
Sweet Taste ◽  
Normal Weight ◽  
Taste Perception ◽  
Taste Sensitivity ◽  
Threshold Detection ◽  
Leptin Receptors ◽  
Whole Saliva

The satiety inducing hormone leptin acts not only at central nervous system but also at peripheral level. Leptin receptors are found in several sense related organs, including the mouth. A role of leptin in sweet taste response has been suggested but, until now, studies have been based on in vitro experiments, or in assessing the levels of the hormone in circulation. The present study investigated whether the levels of leptin in saliva are related to taste perception in children and whether Body Mass Index (BMI) affects such relationship. Sweet and bitter taste sensitivity was assessed for 121 children aged 9-10 years and unstimulated whole saliva was collected for leptin quantification, using ELISA technique. Children females with lower sweet taste sensitivity presented higher salivary leptin levels, but this is only in the normal weight ones. For bitter taste, association between salivary leptin and caffeine threshold detection was observed only in preobese boys, with higher levels of salivary hormone in low sensitive individuals. This study is the first presenting evidences of a relationship between salivary leptin levels and taste perception, which is sex and BMI dependent. The mode of action of salivary leptin at taste receptor level should be elucidated in future studies.

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