International Journal of Molecular Sciences

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16 pages, 5096 KiB

Open AccessArticle

Odorant-Binding and Chemosensory Proteins in Anthonomus eugenii (Coleoptera: Curculionidae) and Their Tissue Expression

by Pablo Lechuga-Paredes, Obdulia Lourdes Segura-León, Juan Cibrián-Tovar, Brenda Torres-Huerta, Julio César Velázquez-González and José Luis Cruz-Jaramillo

Int. J. Mol. Sci. 2023, 24(4), 3406; https://doi.org/10.3390/ijms24043406 - 08 Feb 2023

Cited by 1 | Viewed by 1499

Abstract

The pepper weevil Anthonomus eugenii is one of the most damaging pests to the pepper crop. To offer alternative management strategies to insecticides, several studies have identified the semiochemicals that are involved in the pepper weevil’s aggregation and mating behavior; however, there is [...] Read more.

The pepper weevil Anthonomus eugenii is one of the most damaging pests to the pepper crop. To offer alternative management strategies to insecticides, several studies have identified the semiochemicals that are involved in the pepper weevil’s aggregation and mating behavior; however, there is no information on its perireceptor molecular mechanism, to date. In this study, bioinformatics tools were used to functionally annotate and characterize the A. eugenii head transcriptome and their probable coding proteins. We identified twenty-two transcripts belonging to families related to chemosensory processes, seventeen corresponding to odorant-binding proteins (OBP), and six to chemosensory proteins (CSP). All results matched with closely related Coleoptera: Curculionidae homologous proteins. Likewise, twelve OBP and three CSP transcripts were experimentally characterized by RT-PCR in different female and male tissues. The results by sex and tissue display the different expression patterns of the AeugOBPs and AeugCSPs; some are present in both sexes and all tissues, while others show expressions with higher specificity, which suggests diverse physiological functions in addition to chemo-detection. This study provides information to support the understanding of odor perception in the pepper weevil. Full article

(This article belongs to the Special Issue Molecular and Cellular Mechanisms Underlying Taste, Smell and Beyond)

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11 pages, 2015 KiB

Open AccessArticle

The Third Extracellular Loop of Mammalian Odorant Receptors Is Involved in Ligand Binding

by Tammy Shim, Jody Pacalon, Won-Cheol Kim, Xiaojing Cong, Jérémie Topin, Jérôme Golebiowski and Cheil Moon

Int. J. Mol. Sci. 2022, 23(20), 12501; https://doi.org/10.3390/ijms232012501 - 18 Oct 2022

Cited by 3 | Viewed by 1903

Abstract

Mammals recognize chemicals in the air via G protein-coupled odorant receptors (ORs). In addition to their orthosteric binding site, other segments of these receptors modulate ligand recognition. Focusing on human hOR1A1, which is considered prototypical of class II ORs, we used a combination [...] Read more.

Mammals recognize chemicals in the air via G protein-coupled odorant receptors (ORs). In addition to their orthosteric binding site, other segments of these receptors modulate ligand recognition. Focusing on human hOR1A1, which is considered prototypical of class II ORs, we used a combination of molecular modeling, site-directed mutagenesis, and in vitro functional assays. We showed that the third extracellular loop of ORs (ECL3) contributes to ligand recognition and receptor activation. Indeed, site-directed mutations in ECL3 showed differential effects on the potency and efficacy of both carvones, citronellol, and 2-nonanone. Full article

(This article belongs to the Special Issue Molecular and Cellular Mechanisms Underlying Taste, Smell and Beyond)

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20 pages, 5045 KiB

Open AccessArticle

Identification of Candidate Chemosensory Gene Families by Head Transcriptomes Analysis in the Mexican Fruit Fly, Anastrepha ludens Loew (Diptera: Tephritidae)

by Obdulia L. Segura-León, Brenda Torres-Huerta, Alan Rubén Estrada-Pérez, Juan Cibrián-Tovar, Fidel de la Cruz Hernandez-Hernandez, José Luis Cruz-Jaramillo, José Salvador Meza-Hernández and Fabian Sánchez-Galicia

Int. J. Mol. Sci. 2022, 23(18), 10531; https://doi.org/10.3390/ijms231810531 - 11 Sep 2022

Cited by 3 | Viewed by 2179

Abstract

Insect chemosensory systems, such as smell and taste, are mediated by chemosensory receptor and non-receptor protein families. In the last decade, many studies have focused on discovering these families in Tephritidae species of agricultural importance. However, to date, there is no information on [...] Read more.

Insect chemosensory systems, such as smell and taste, are mediated by chemosensory receptor and non-receptor protein families. In the last decade, many studies have focused on discovering these families in Tephritidae species of agricultural importance. However, to date, there is no information on the Mexican fruit fly Anastrepha ludens Loew, a priority pest of quarantine importance in Mexico and other countries. This work represents the first effort to identify, classify and characterize the six chemosensory gene families by analyzing two head transcriptomes of sexually immature and mature adults of A. ludens from laboratory-reared and wild populations, respectively. We identified 120 chemosensory genes encoding 31 Odorant-Binding Proteins (OBPs), 5 Chemosensory Proteins (CSPs), 2 Sensory Neuron Membrane Proteins (SNMPs), 42 Odorant Receptors (ORs), 17 Ionotropic Receptors (IRs), and 23 Gustatory Receptors (GRs). The 120 described chemosensory proteins of the Mexican fruit fly significantly contribute to the genetic databases of insects, particularly dipterans. Except for some OBPs, this work reports for the first time the repertoire of olfactory proteins for one species of the genus Anastrepha, which provides a further basis for studying the olfactory system in the family Tephritidae, one of the most important for its economic and social impact worldwide. Full article

(This article belongs to the Special Issue Molecular and Cellular Mechanisms Underlying Taste, Smell and Beyond)

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12 pages, 2431 KiB

Open AccessArticle

Functional Characterization of the Venus Flytrap Domain of the Human TAS1R2 Sweet Taste Receptor

by Anni Laffitte, Christine Belloir, Fabrice Neiers and Loïc Briand

Int. J. Mol. Sci. 2022, 23(16), 9216; https://doi.org/10.3390/ijms23169216 - 16 Aug 2022

Cited by 5 | Viewed by 1859

Abstract

The human sweet taste receptor is a heterodimeric receptor composed of two distinct G-protein-coupled receptors (GPCRs), TAS1R2 and TAS1R3. The TAS1R2 and TAS1R3 subunits are members of a small family of class C GPCRs whose members share the same architecture, comprising a Venus [...] Read more.

The human sweet taste receptor is a heterodimeric receptor composed of two distinct G-protein-coupled receptors (GPCRs), TAS1R2 and TAS1R3. The TAS1R2 and TAS1R3 subunits are members of a small family of class C GPCRs whose members share the same architecture, comprising a Venus Flytrap (VFT) module linked to the seven transmembrane domains (TMDs) by a short cysteine-rich region (CRR). The VFT module of TAS1R2 contains the primary binding site for most of the sweet-tasting compounds, including natural sugars and artificial and natural sweeteners. However, cellular assays, molecular docking and site-directed mutagenesis studies have revealed that the VFT, CRR and TMD of TAS1R3 interact with some sweeteners, including the sweet-tasting protein brazzein. The aim of this study was to better understand the contribution of TAS1R2-VFT in the binding of sweet stimuli. To achieve this, we heterologously expressed human TAS1R2-VFT (hTAS1R2-VFT) in Escherichia coli. Circular dichroism spectroscopic studies revealed that hTAS1R2-VFT was properly folded with evidence of secondary structures. Using size-exclusion chromatography coupled with light scattering, we found that hTAS1R2-VFT behaves as a monomer. Ligand binding quantified by intrinsic tryptophan fluorescence showed that hTAS1R2-VFT is capable of binding sweet stimuli with K_d values, in agreement with physiological detection. Furthermore, we investigated whether the impact of point mutations, already shown to have deleterious effects on cellular assays, could impact the ability of hTAS1R2-VFT to bind sweet ligands. As expected, the ligand affinities of hTAS1R2-VFT were drastically reduced through the introduction of single amino acid substitutions (D278A and E382A) known to abolish the response of the full-length TAS1R2/TAS1R3 receptor. This study demonstrates the feasibility of producing milligram quantities of hTAS1R2-VFT to further characterize the mechanism of binding interaction and perform structural studies. Full article

(This article belongs to the Special Issue Molecular and Cellular Mechanisms Underlying Taste, Smell and Beyond)

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13 pages, 8260 KiB

Open AccessArticle

Localization of BDNF and Calretinin in Olfactory Epithelium and Taste Buds of Zebrafish (Danio rerio)

by Marialuisa Aragona, Caterina Porcino, Maria Cristina Guerrera, Giuseppe Montalbano, Rosaria Laurà, Maria Levanti, Francesco Abbate, Teresa Cobo, Gabriel Capitelli, Fabrizio Calapai, José A Vega and Antonino Germanà

Int. J. Mol. Sci. 2022, 23(9), 4696; https://doi.org/10.3390/ijms23094696 - 23 Apr 2022

Cited by 9 | Viewed by 2194

Abstract

Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin family and it is involved in several fundamental functions in the central and peripheral nervous systems, and in sensory organs. BDNF regulates the chemosensory systems of mammals and is consistently expressed in those [...] Read more.

Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin family and it is involved in several fundamental functions in the central and peripheral nervous systems, and in sensory organs. BDNF regulates the chemosensory systems of mammals and is consistently expressed in those organs. In zebrafish, the key role of BDNF in the biology of the hair cells of the inner ear and lateral line system has recently been demonstrated. However, only some information is available about its occurrence in the olfactory epithelium, taste buds, and cutaneous isolated chemosensory cells. Therefore, this study was undertaken to analyze the involvement of BDNF in the chemosensory organs of zebrafish during the larval and adult stages. To identify cells displaying BDNF, we compared the cellular pattern of BDNF-displaying cells with those immunoreactive for calretinin and S100 protein. Our results demonstrate the localization of BDNF in the sensory part of the olfactory epithelium, mainly in the ciliated olfactory sensory neurons in larvae and adult zebrafish. Intense immunoreaction for BDNF was also observed in the chemosensory cells of oral and cutaneous taste buds. Moreover, a subpopulation of olfactory sensory neurons and chemosensory cells of olfactory rosette and taste bud, respectively, showed marked immunopositivity for calcium-binding protein S100 and calretinin. These results demonstrate the possible role of BDNF in the development and maintenance of olfactory sensory neurons and sensory cells in the olfactory epithelium and taste organs of zebrafish during all stages of development. Full article

(This article belongs to the Special Issue Molecular and Cellular Mechanisms Underlying Taste, Smell and Beyond)

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Review

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18 pages, 12929 KiB

Open AccessReview

Anterior and Posterior Tongue Regions and Taste Papillae: Distinct Roles and Regulatory Mechanisms with an Emphasis on Hedgehog Signaling and Antagonism

by Archana Kumari and Charlotte M. Mistretta

Int. J. Mol. Sci. 2023, 24(5), 4833; https://doi.org/10.3390/ijms24054833 - 02 Mar 2023

Cited by 1 | Viewed by 3405

Abstract

Sensory receptors across the entire tongue are engaged during eating. However, the tongue has distinctive regions with taste (fungiform and circumvallate) and non-taste (filiform) organs that are composed of specialized epithelia, connective tissues, and innervation. The tissue regions and papillae are adapted in [...] Read more.

Sensory receptors across the entire tongue are engaged during eating. However, the tongue has distinctive regions with taste (fungiform and circumvallate) and non-taste (filiform) organs that are composed of specialized epithelia, connective tissues, and innervation. The tissue regions and papillae are adapted in form and function for taste and somatosensation associated with eating. It follows that homeostasis and regeneration of distinctive papillae and taste buds with particular functional roles require tailored molecular pathways. Nonetheless, in the chemosensory field, generalizations are often made between mechanisms that regulate anterior tongue fungiform and posterior circumvallate taste papillae, without a clear distinction that highlights the singular taste cell types and receptors in the papillae. We compare and contrast signaling regulation in the tongue and emphasize the Hedgehog pathway and antagonists as prime examples of signaling differences in anterior and posterior taste and non-taste papillae. Only with more attention to the roles and regulatory signals for different taste cells in distinct tongue regions can optimal treatments for taste dysfunctions be designed. In summary, if tissues are studied from one tongue region only, with associated specialized gustatory and non-gustatory organs, an incomplete and potentially misleading picture will emerge of how lingual sensory systems are involved in eating and altered in disease. Full article

(This article belongs to the Special Issue Molecular and Cellular Mechanisms Underlying Taste, Smell and Beyond)

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22 pages, 538 KiB

Open AccessReview

The Impact of Taste Preference-Related Gene Polymorphisms on Alcohol Consumption Behavior: A Systematic Review

by Ali Abbas Mohammad Kurshed, Róza Ádány and Judit Diószegi

Int. J. Mol. Sci. 2022, 23(24), 15989; https://doi.org/10.3390/ijms232415989 - 15 Dec 2022

Cited by 4 | Viewed by 1946

Abstract

Unhealthy alcohol consumption is recognized as a leading contributory factor to mortality and disability. In addition to other factors, taste sensation also mediates alcohol intake. The orosensation provoked by alcoholic drinks may vary across individuals and may be responsible for differences in preference [...] Read more.

Unhealthy alcohol consumption is recognized as a leading contributory factor to mortality and disability. In addition to other factors, taste sensation also mediates alcohol intake. The orosensation provoked by alcoholic drinks may vary across individuals and may be responsible for differences in preference for alcoholic beverages. Thus, individual genetic variability of taste preference may have an impact on alcohol consumption practices. The present review aimed to explore the associations between different taste preference polymorphisms and alcohol consumption behavior. Based on the PRISMA statement, the three databases PubMed, Web of Science and ProQuest Central were searched to identify articles and the Q-Genie tool was used to assess the quality of the included studies. Among the 17 studies included in this review, 5 and 12 were of good and moderate quality, respectively. Most of the studies analyzed TAS2R38 (taste 2 receptor member 38) rs713598, rs1726866, rs10246939 polymorphisms. Due to the inconclusive findings on these variants and the very limited number of studies on other polymorphisms, additional extensive research is recommended to replicate the existing findings, to generate new knowledge to enhance our understanding of the complexity of alcohol consumption behavior and to aid the development of personalized recommendations on unhealthy alcohol use. Full article

(This article belongs to the Special Issue Molecular and Cellular Mechanisms Underlying Taste, Smell and Beyond)

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15 pages, 302 KiB

Open AccessReview

Taste Receptors beyond Taste Buds

by Su Young Ki and Yong Taek Jeong

Int. J. Mol. Sci. 2022, 23(17), 9677; https://doi.org/10.3390/ijms23179677 - 26 Aug 2022

Cited by 6 | Viewed by 2693

Abstract

Taste receptors are responsible for detecting their ligands not only in taste receptor cells (TRCs) but also in non-gustatory organs. For several decades, many research groups have accumulated evidence for such “ectopic” expression of taste receptors. More recently, some of the physiologic functions [...] Read more.

Taste receptors are responsible for detecting their ligands not only in taste receptor cells (TRCs) but also in non-gustatory organs. For several decades, many research groups have accumulated evidence for such “ectopic” expression of taste receptors. More recently, some of the physiologic functions (apart from taste) of these ectopic taste receptors have been identified. Here, we summarize our current understanding of these ectopic taste receptors across multiple organs. With a particular focus on the specialized epithelial cells called tuft cells, which are now considered siblings of type II TRCs, we divide the ectopic expression of taste receptors into two categories: taste receptors in TRC-like cells outside taste buds and taste receptors with surprising ectopic expression in completely different cell types. Full article

(This article belongs to the Special Issue Molecular and Cellular Mechanisms Underlying Taste, Smell and Beyond)

15 pages, 1414 KiB

Open AccessReview

Sweet Taste Signaling: The Core Pathways and Regulatory Mechanisms

by Sunil Kumar Sukumaran and Salin Raj Palayyan

Int. J. Mol. Sci. 2022, 23(15), 8225; https://doi.org/10.3390/ijms23158225 - 26 Jul 2022

Cited by 2 | Viewed by 5239

Abstract

Sweet taste, a proxy for sugar-derived calories, is an important driver of food intake, and animals have evolved robust molecular and cellular machinery for sweet taste signaling. The overconsumption of sugar-derived calories is a major driver of obesity and other metabolic diseases. A [...] Read more.

Sweet taste, a proxy for sugar-derived calories, is an important driver of food intake, and animals have evolved robust molecular and cellular machinery for sweet taste signaling. The overconsumption of sugar-derived calories is a major driver of obesity and other metabolic diseases. A fine-grained appreciation of the dynamic regulation of sweet taste signaling mechanisms will be required for designing novel noncaloric sweeteners with better hedonic and metabolic profiles and improved consumer acceptance. Sweet taste receptor cells express at least two signaling pathways, one mediated by a heterodimeric G-protein coupled receptor encoded by taste 1 receptor members 2 and 3 (TAS1R2 + TAS1R3) genes and another by glucose transporters and the ATP-gated potassium (K_ATP) channel. Despite these important discoveries, we do not fully understand the mechanisms regulating sweet taste signaling. We will introduce the core components of the above sweet taste signaling pathways and the rationale for having multiple pathways for detecting sweet tastants. We will then highlight the roles of key regulators of the sweet taste signaling pathways, including downstream signal transduction pathway components expressed in sweet taste receptor cells and hormones and other signaling molecules such as leptin and endocannabinoids. Full article

(This article belongs to the Special Issue Molecular and Cellular Mechanisms Underlying Taste, Smell and Beyond)

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