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Yuko Kawabata, Shingo Takai, Keisuke Sanematsu, Ryusuke Yoshida, Fuminori Kawabata, Noriatsu Shigemura, The antiarrhythmic drug flecainide enhances aversion to HCl in mice., eNeuro, 10.1523/ENEURO.0048-23.2023, 2023.09, Drug-induced taste disorders reduce quality of life, but little is known about the molecular mechanisms by which drugs induce taste disturbances. In this study, we investigated the short- and long-term effects of the antiarrhythmic drug flecainide, which is known to cause taste dysfunction. Analyses of behavioral responses (licking tests) revealed that mice given a single intraperitoneal injection of flecainide exhibited a significant reduction in preference for a sour tastant (HCl) but not for other taste solutions (NaCl, quinine, sucrose, KCl and monopotassium glutamate) when compared with controls. Mice administered a single dose of flecainide also had significantly higher taste nerve responses to HCl but not to other taste solutions. Compared with controls, mice administered flecainide once-daily for 30 days showed a reduced preference for HCl without any changes in the behavioral responses to other taste solutions. The electrophysiological experiments using HEK293T cells transiently expressing otopetrin-1 (Otop1, the mouse sour taste receptor) showed that flecainide rarely altered the responses to HCl. Taken together, our results suggest that flecainide specifically enhances the response to HCl in mice during short- and long- term administration. Although further studies will be needed to elucidate the molecular mechanisms, these findings provide new insights into the pathophysiology of drug-induced taste disorders.Significance StatementDrug-induced taste disorders reduce quality of life and can lead to nutritional disturbances. However, little is known about its molecular mechanisms. We focused on the antiarrhythmic drug flecainide inducing "unpleasant or bad taste" in human patients. Mice administered a single dose of flecainide exhibited a reduced preference for and higher taste nerve responses to HCl, sour tastants specifically. Flecainide had little change in response to HCl in HEK293T cells expressing the sour taste receptor, proton channel otopetrin-1 (Otop1). Our results suggest that flecainide enhances the responses of sour-sensing taste cells to HCl. Although further studies will be needed to elucidate the molecular mechanisms, these findings provide new insights into the pathophysiology of drug-induced taste disorders.. |
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Shusuke Iwata, Ryusuke Yoshida, Shingo Takai, Keisuke Sanematsu, Noriatsu Shigemura, Yuzo Ninomiya, Adrenomedullin Enhances Mouse Gustatory Nerve Responses to Sugars via T1R-Independent Sweet Taste Pathway, Nutrients, 10.3390/nu15132941, 15, 13, 2941-2941, 2023.06, On the tongue, the T1R-independent pathway (comprising glucose transporters, including sodium–glucose cotransporter (SGLT1) and the KATP channel) detects only sugars, whereas the T1R-dependent (T1R2/T1R3) pathway can broadly sense various sweeteners. Cephalic-phase insulin release, a rapid release of insulin induced by sensory signals in the head after food-related stimuli, reportedly depends on the T1R-independent pathway, and the competitive sweet taste modulators leptin and endocannabinoids may function on these two different sweet taste pathways independently, suggesting independent roles of two oral sugar-detecting pathways in food intake. Here, we examined the effect of adrenomedullin (ADM), a multifunctional regulatory peptide, on sugar sensing in mice since it affects the expression of SGLT1 in rat enterocytes. We found that ADM receptor components were expressed in T1R3-positive taste cells. Analyses of chorda tympani (CT) nerve responses revealed that ADM enhanced responses to sugars but not to artificial sweeteners and other tastants. Moreover, ADM increased the apical uptake of a fluorescent D-glucose derivative into taste cells and SGLT1 mRNA expression in taste buds. These results suggest that the T1R-independent sweet taste pathway in mouse taste cells is a peripheral target of ADM, and the specific enhancement of gustatory nerve responses to sugars by ADM may contribute to caloric sensing and food intake.. |
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Keisuke Sanematsu, Masato Yamamoto, Yuki Nagasato, Yuko Kawabata, Yu Watanabe, Shusuke Iwata, Shingo Takai, Kiyoshi Toko, Toshiro Matsui, Naohisa Wada, Noriatsu Shigemura, Prediction of dynamic allostery for the transmembrane domain of the sweet taste receptor subunit, TAS1R3., Communications biology, 10.1038/s42003-023-04705-5, 6, 1, 340-340, 2023.04, The sweet taste receptor plays an essential role as an energy sensor by detecting carbohydrates. However, the dynamic mechanisms of receptor activation remain unclear. Here, we describe the interactions between the transmembrane domain of the G protein-coupled sweet receptor subunit, TAS1R3, and allosteric modulators. Molecular dynamics simulations reproduced species-specific sensitivity to ligands. We found that a human-specific sweetener, cyclamate, interacted with the mouse receptor as a negative allosteric modulator. Agonist-induced allostery during receptor activation was found to destabilize the intracellular part of the receptor, which potentially interfaces with the Gα subunit, through ionic lock opening. A common human variant (R757C) of the TAS1R3 exhibited a reduced response to sweet taste, in support of our predictions. Furthermore, histidine residues in the binding site acted as pH-sensitive microswitches to modulate the sensitivity to saccharin. This study provides important insights that may facilitate the prediction of dynamic activation mechanisms for other G protein-coupled receptors.. |
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Kae Matsuyama, Shingo Takai, Noriatsu Shigemura, Mitsushiro Nakatomi, Tatsuo Kawamoto, Shinji Kataoka, Takashi Toyono, Yuji Seta, Ascl1-expressing cell differentiation in initially developed taste buds and taste organoids., Cell and tissue research, 10.1007/s00441-023-03756-8, 2023.02, Mammalian taste bud cells are composed of several distinct cell types and differentiated from surrounding tongue epithelial cells. However, the detailed mechanisms underlying their differentiation have yet to be elucidated. In the present study, we examined an Ascl1-expressing cell lineage using circumvallate papillae (CVP) of newborn mice and taste organoids (three-dimensional self-organized tissue cultures), which allow studying the differentiation of taste bud cells in fine detail ex vivo. Using lineage-tracing analysis, we observed that Ascl1 lineage cells expressed type II and III taste cell markers both CVP of newborn mice and taste organoids. However, the coexpression rate in type II cells was lower than that in type III cells. Furthermore, we found that the generation of the cells which express type II and III cell markers was suppressed in taste organoids lacking Ascl1-expressing cells. These findings suggest that Ascl1-expressing precursor cells can differentiate into both type III and a subset of type II taste cells.. |
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Asami Oike, Shusuke Iwata, Ayaka Hirayama, Yurika Ono, Yuki Nagasato, Yuko Kawabata, Shingo Takai, Keisuke Sanematsu, Naohisa Wada, Noriatsu Shigemura, Bisphosphonate affects the behavioral responses to HCl by disrupting farnesyl diphosphate synthase in mouse taste bud and tongue epithelial cells., Scientific reports, 10.1038/s41598-022-25755-5, 12, 1, 21246-21246, 2022.12, Little is known about the molecular mechanisms underlying drug-induced taste disorders, which can cause malnutrition and reduce quality of life. One of taste disorders is known adverse effects of bisphosphonates, which are administered as anti-osteoporotic drugs. Therefore, the present study evaluated the effects of risedronate (a bisphosphonate) on taste bud cells. Expression analyses revealed that farnesyl diphosphate synthase (FDPS, a key enzyme in the mevalonate pathway) was present in a subset of mouse taste bud and tongue epithelial cells, especially type III sour-sensitive taste cells. Other mevalonate pathway-associated molecules were also detected in mouse taste buds. Behavioral analyses revealed that mice administered risedronate exhibited a significantly enhanced aversion to HCl but not for other basic taste solutions, whereas the taste nerve responses were not affected by risedronate. Additionally, the taste buds of mice administered risedronate exhibited significantly lower mRNA expression of desmoglein-2, an integral component of desmosomes. Taken together, these findings suggest that risedronate may interact directly with FDPS to inhibit the mevalonate pathway in taste bud and tongue epithelial cells, thereby affecting the expression of desmoglein-2 related with epithelial barrier function, which may lead to alterations in behavioral responses to HCl via somatosensory nerves.. |
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Yu Yamada, Shingo Takai, Yu Watanabe, Ayana Osaki, Yuko Kawabata, Asami Oike, Ayaka Hirayama, Shusuke Iwata, Keisuke Sanematsu, Shoji Tabata, Noriatsu Shigemura, Gene expression profiling of α-gustducin-expressing taste cells in mouse fungiform and circumvallate papillae, Biochemical and Biophysical Research Communications, 10.1016/j.bbrc.2021.04.022, 2021.06. |
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Ayana Osaki, Keisuke Sanematsu, Junichi Yamazoe, Fumie Hirose, Yu Watanabe, Yuko Kawabata, Asami Oike, Ayaka Hirayama, Yu Yamada, Shusuke Iwata, Shingo Takai, Naohisa Wada, Noriatsu Shigemura, Drinking Ice-Cold Water Reduces the Severity of Anticancer Drug-Induced Taste Dysfunction in Mice., International journal of molecular sciences, 10.3390/ijms21238958, 21, 23, 2020.11, Taste disorders are common adverse effects of cancer chemotherapy that can reduce quality of life and impair nutritional status. However, the molecular mechanisms underlying chemotherapy-induced taste disorders remain largely unknown. Furthermore, there are no effective preventive measures for chemotherapy-induced taste disorders. We investigated the effects of a combination of three anticancer drugs (TPF: docetaxel, cisplatin and 5-fluorouracil) on the structure and function of mouse taste tissues and examined whether the drinking of ice-cold water after TPF administration would attenuate these effects. TPF administration significantly increased the number of cells expressing apoptotic and proliferative markers. Furthermore, TPF administration significantly reduced the number of cells expressing taste cell markers and the magnitudes of the responses of taste nerves to tastants. The above results suggest that anticancer drug-induced taste dysfunction may be due to a reduction in the number of taste cells expressing taste-related molecules. The suppressive effects of TPF on taste cell marker expression and taste perception were reduced by the drinking of ice-cold water. We speculate that oral cryotherapy with an ice cube might be useful for prophylaxis against anticancer drug-induced taste disorders in humans.. |
| 8. |
Takai S, Shigemura N, Insulin function in peripheral taste organ homeostasis, Current Oral Health Reports, 10.1007/s40496-020-00266-2, 7, 168-173, 2020.03. |
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Shingo Takai, Yu Watanabe, Keisuke Sanematsu, Ryusuke Yoshida, Robert F. Margolskee, Peihua Jiang, Ikiru Atsuta, Kiyoshi Koyano, Yuzo Ninomiya, Noriatsu Shigemura, Effects of insulin signaling on mouse taste cell proliferation, PloS one, 10.1371/journal.pone.0225190, 14, 11, 2019.11, Expression of insulin and its receptor (IR) in rodent taste cells has been proposed, but exactly which types of taste cells express IR and the function of insulin signaling in taste organ have yet to be determined. In this study, we analyzed expression of IR mRNA and protein in mouse taste bud cells in vivo and explored its function ex vivo in organoids, using RT-PCR, immunohistochemistry, and quantitative PCR. In mouse taste tissue, IR was expressed broadly in taste buds, including in type II and III taste cells. With using 3-D taste bud organoids, we found insulin in the culture medium significantly decreased the number of taste cell and mRNA expression levels of many taste cell genes, including nucleoside triphosphate diphosphohydrolase-2 (NTPDase2), Tas1R3 (T1R3), gustducin, carbonic anhydrase 4 (CA4), glucose transporter-8 (GLUT8), and sodium-glucose cotransporter-1 (SGLT1) in a concentration-dependent manner. Rapamycin, an inhibitor of mechanistic target of rapamycin (mTOR) signaling, diminished insulin’s effects and increase taste cell generation. Altogether, circulating insulin might be an important regulator of taste cell growth and/or proliferation via activation of the mTOR pathway.. |
| 10. |
Ryusuke Yoshida, Misa Shin, Keiko Yasumatsu, Shingo Takai, Mayuko Inoue, Noriatsu Shigemura, Soichi Takiguchi, Seiji Nakamura, Yuzo Ninomiya, The role of cholecystokinin in peripheral taste signaling in mice, Frontiers in Physiology, 10.3389/fphys.2017.00866, 8, OCT, 866, 2017.10, © 2017 Yoshida, Shin, Yasumatsu, Takai, Inoue, Shigemura, Takiguchi, Nakamura and Ninomiya. Cholecystokinin (CCK) is a gut hormone released from enteroendocrine cells. CCK functions as an anorexigenic factor by acting on CCK receptors expressed on the vagal afferent nerve and hypothalamus with a synergistic interaction between leptin. In the gut, tastants such as amino acids and bitter compounds stimulate CCK release from enteroendocrine cells via activation of taste transduction pathways. CCK is also expressed in taste buds, suggesting potential roles of CCK in taste signaling in the peripheral taste organ. In the present study, we focused on the function of CCK in the initial responses to taste stimulation. CCK was coexpressed with type II taste cell markers such as Ga-gustducin, phospholipase Cß2, and transient receptor potential channel M5. Furthermore, a small subset (~30%) of CCK-expressing taste cells expressed a sweet/umami taste receptor component, taste receptor type 1 member 3, in taste buds. Because type II taste cells are sweet, umami or bitter taste cells, the majority of CCK-expressing taste cells may be bitter taste cells. CCK-A and -B receptors were expressed in both taste cells and gustatory neurons. CCK receptor knockout mice showed reduced neural responses to bitter compounds compared with wild-type mice. Consistently, intravenous injection of CCK-Ar antagonist lorglumide selectively suppressed gustatory nerve responses to bitter compounds. Intravenous injection of CCK-8 transiently increased gustatory nerve activities in a dose-dependent manner whereas administration of CCK-8 did not affect activities of bitter-sensitive taste cells. Collectively, CCK may be a functionally important neurotransmitter or neuromodulator to activate bitter nerve fibers in peripheral taste tissues.. |
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Mayu Niki, Ryusuke Yoshida, Shingo Takai, Yuzo Ninomiya, Gustatory signaling in the periphery
Detection, transmission, and modulation of taste information, Biological and Pharmaceutical Bulletin, 10.1248/bpb.33.1772, 33, 11, 1772-1777, 2010.11, Gustatory signaling begins with taste receptor cells that express taste receptors. Recent molecular biological studies have identified taste receptors and transduction components for basic tastes (sweet, salty, sour, bitter, and umami). Activation of these receptor systems leads to depolarization and an increase in [Ca2+]i in taste receptor cells. Then transmitters are released from taste cells and activate gustatory nerve fibers. The connection between taste cells and gustatory nerve fibers would be specific because there may be only limited divergence of taste information at the peripheral transmission. Recent studies have demonstrated that sweet taste information can be modulated by hormones or other endogenous factors that could act on their receptors in a specific group of taste cells. These peripheral modulations of taste information may influence preference behavior and food intake. This paper summarizes data on molecular mechanisms for detection and transduction of taste signals in taste bud cells, information transmission from taste cells to gustatory nerve fibers, and modulation of taste signals at peripheral taste organs, in particular for sweet taste, which may play important roles in regulating energy homeostasis.. |
