1
|
Moribayashi T, Nakao Y, Ohtubo Y. Characteristics of A-type voltage-gated K + currents expressed on sour-sensing type III taste receptor cells in mice. Cell Tissue Res 2024; 396:353-369. [PMID: 38492001 PMCID: PMC11144136 DOI: 10.1007/s00441-024-03887-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Accepted: 03/06/2024] [Indexed: 03/18/2024]
Abstract
Sour taste is detected by type III taste receptor cells that generate membrane depolarization with action potentials in response to HCl applied to the apical membranes. The shape of action potentials in type III cells exhibits larger afterhyperpolarization due to activation of transient A-type voltage-gated K+ currents. Although action potentials play an important role in neurotransmitter release, the electrophysiological features of A-type K+ currents in taste buds remain unclear. Here, we examined the electrophysiological properties of A-type K+ currents in mouse fungiform taste bud cells using in-situ whole-cell patch clamping. Type III cells were identified with SNAP-25 immunoreactivity and/or electrophysiological features of voltage-gated currents. Type III cells expressed A-type K+ currents which were completely inhibited by 10 mM TEA, whereas IP3R3-immunoreactive type II cells did not. The half-maximal activation and steady-state inactivation of A-type K+ currents were 17.9 ± 4.5 (n = 17) and - 11.0 ± 5.7 (n = 17) mV, respectively, which are similar to the features of Kv3.3 and Kv3.4 channels (transient and high voltage-activated K+ channels). The recovery from inactivation was well fitted with a double exponential equation; the fast and slow time constants were 6.4 ± 0.6 ms and 0.76 ± 0.26 s (n = 6), respectively. RT-PCR experiments suggest that Kv3.3 and Kv3.4 mRNAs were detected at the taste bud level, but not at single-cell levels. As the phosphorylation of Kv3.3 and Kv3.4 channels generally leads to the modulation of cell excitability, neuromodulator-mediated A-type K+ channel phosphorylation likely affects the signal transduction of taste.
Collapse
Affiliation(s)
- Takeru Moribayashi
- Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, Hibikino 2-4, Kitakyushu, 808-0196, Japan
| | - Yoshiki Nakao
- Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, Hibikino 2-4, Kitakyushu, 808-0196, Japan
| | - Yoshitaka Ohtubo
- Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, Hibikino 2-4, Kitakyushu, 808-0196, Japan.
| |
Collapse
|
2
|
Inoko S, Katagiri H, Tsujimura M, Yoshie S. The existence of cells exhibiting characteristics of both Type II and Type III cells in rat taste buds. An immunohistochemical and electron-microscopic study. Odontology 2024:10.1007/s10266-024-00948-8. [PMID: 38796802 DOI: 10.1007/s10266-024-00948-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Accepted: 05/04/2024] [Indexed: 05/29/2024]
Abstract
Taste bud cells are classified into four types by their ultrastructural features. Immunohistochemical detection of taste-signaling molecules is used to distinguish cell types of taste bud cells; however, the characteristics of taste cell types such as the immunoreactivity for taste-signaling molecules have long remained unclear. We investigated the detailed characteristics of taste cells in rat vallate taste buds by electron microscopy and immunohistochemistry for gustducin, neural cell adhesion molecule (NCAM) and vesicle-associated membrane protein 2 (VAMP2), which are known as markers of Type II cells, Type III cells and both cell types, respectively. Triple immunostaining for these molecules discriminated seven kinds of cell, including the totally immunopositive cell. Electron microscopy revealed Type III cells with a typical synaptic structure and subsurface cisterna as a specialized contact between a nerve and a Type II cell. The present study clarified the existence of cells with features of both Type II and Type III cells as a subtype of taste bud cells in the rat taste bud.
Collapse
Affiliation(s)
- Shuhei Inoko
- Histology, The Nippon Dental University Graduate School of Life Dentistry at Niigata, 1-8 Hamaura-Cho, Chuo-Ku, Niigata, 951-8580, Japan
| | - Hiroki Katagiri
- Department of Histology, The Nippon Dental University School of Life Dentistry at Niigata, 1-8 Hamaura-Cho, Chuo-Ku, Niigata, 951-8580, Japan
- Department of Microbiology, The Nippon Dental University School of Life Dentistry at Niigata, Niigata, Japan
- Advanced Research Center, The Nippon Dental University School of Life Dentistry at Niigata, Niigata, Japan
| | - Maiko Tsujimura
- Histology, The Nippon Dental University Graduate School of Life Dentistry at Niigata, 1-8 Hamaura-Cho, Chuo-Ku, Niigata, 951-8580, Japan.
- Department of Histology, The Nippon Dental University School of Life Dentistry at Niigata, 1-8 Hamaura-Cho, Chuo-Ku, Niigata, 951-8580, Japan.
- Advanced Research Center, The Nippon Dental University School of Life Dentistry at Niigata, Niigata, Japan.
| | - Sumio Yoshie
- Department of Histology, The Nippon Dental University School of Life Dentistry at Niigata, 1-8 Hamaura-Cho, Chuo-Ku, Niigata, 951-8580, Japan.
| |
Collapse
|
3
|
Obayashi N, Sakayori N, Kawaguchi H, Sugita M. Effect of irinotecan administration on amiloride-sensitive sodium taste responses in mice. Eur J Oral Sci 2023; 131:e12922. [PMID: 36852977 DOI: 10.1111/eos.12922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 01/25/2023] [Indexed: 03/01/2023]
Abstract
Taste alteration is a frequently reported side effect in patients receiving the chemotherapeutic agent, irinotecan. However, the way in which irinotecan causes taste disturbance and the type of taste impairment that is affected remain elusive. Here, we used the two-bottle preference test to characterize behavioral taste responses and employed immunohistochemical analyses to clarify the types and mechanisms of taste alteration induced, in mice, by irinotecan administration. Irinotecan administration resulted in a reduced intake of sodium taste solution but had no effect on sweet taste responses, as determined in the two-bottle preference test. In the presence of amiloride, which inhibits the function of the epithelial sodium channel (ENaC) in the periphery, the intake of sodium taste solution was comparable between the irinotecan-treated and control groups. Immunohistochemical analyses revealed that α-ENaC immunoreactivity detected in taste bud cells decreased slowly after irinotecan administration, and that administration of irinotecan had little effect on the number of cells expressing the cellular proliferation marker, Ki67, within or around taste buds. Our results imply that irinotecan administration may be responsible for altered behavioral sodium taste responses originating from ENaC function in the periphery, while being accompanied by the reduction of α-ENaC expression at the apical membrane of taste receptor cells without disturbing taste cell renewal.
Collapse
Affiliation(s)
- Nami Obayashi
- Department of Physiology and Oral Physiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
- Department of General Dentistry, Hiroshima University Hospital, Hiroshima, Japan
| | - Nobuyuki Sakayori
- Department of Physiology and Oral Physiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Hiroyuki Kawaguchi
- Department of General Dentistry, Hiroshima University Hospital, Hiroshima, Japan
| | - Makoto Sugita
- Department of Physiology and Oral Physiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| |
Collapse
|
4
|
Yokoyama T, Ito M, Yamamoto Y, Hirakawa M, Sakanoue W, Sato K, Saino T. Immunolocalization of vesicular glutamate transporter 2 and exocytosis-related proteins in afferent nerve endings innervating taste buds in the rat incisive papilla. Anat Histol Embryol 2023. [PMID: 36825501 DOI: 10.1111/ahe.12911] [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: 11/29/2022] [Revised: 01/17/2023] [Accepted: 02/07/2023] [Indexed: 02/25/2023]
Abstract
The present study aimed to investigate the immunolocalization of vesicular glutamate transporter (VGLUT) 1 and 2, and proteins associated with exocytosis, i.e., core components of the soluble N-ethylmaleimide-sensitive factor attachment protein receptor complex (synaptosomal-associated protein of 25 kDa, syntaxin 1, and vesicle-associated membrane protein 2) and synaptotagmin-1 (Syt1), in incisive papillary taste buds of rats using double-indirect immunofluorescence. No VGLUT1 immunoreactivity was observed, whereas VGLUT2-immunoreactive punctate products were closely associated with guanine nucleotide-binding protein G(t) subunit α3-immmunoreactive cells in taste buds. VGLUT2 was immunolocalized in P2X3 purinoceptor-expressing afferent nerve endings. Synaptosomal-associated protein of 25 kDa, syntaxin 1, and vesicle-associated membrane protein 2 were immunolocalized in nerve endings containing VGLUT2-immunoreactive products as well as a few cells in taste buds. VGLUT2 was co-immunolocalized in some intragemmal nerve endings immunoreactive for Syt1, a calcium sensor implicated in vesicle membrane fusion. The present results suggest that afferent nerve endings innervating incisive taste buds release glutamate by exocytosis to modulate taste cell function.
Collapse
Affiliation(s)
- Takuya Yokoyama
- Department of Anatomy (Cell Biology), Iwate Medical University, Yahaba, Japan
| | - Motoi Ito
- Division of Dental Anesthesiology, Department of Reconstructive Oral and Maxillofacial Surgery, School of Dentistry, Iwate Medical University, Yahaba, Japan
| | - Yoshio Yamamoto
- Laboratory of Veterinary Anatomy and Cell Biology, Faculty of Agriculture, Iwate University, Morioka, Japan
| | - Masato Hirakawa
- Department of Anatomy (Cell Biology), Iwate Medical University, Yahaba, Japan
| | - Wakana Sakanoue
- Division of Dental Anesthesiology, Department of Reconstructive Oral and Maxillofacial Surgery, School of Dentistry, Iwate Medical University, Yahaba, Japan
| | - Kenichi Sato
- Division of Dental Anesthesiology, Department of Reconstructive Oral and Maxillofacial Surgery, School of Dentistry, Iwate Medical University, Yahaba, Japan
| | - Tomoyuki Saino
- Department of Anatomy (Cell Biology), Iwate Medical University, Yahaba, Japan
| |
Collapse
|
5
|
Matsuyama K, Takai S, Shigemura N, Nakatomi M, Kawamoto T, Kataoka S, Toyono T, Seta Y. Ascl1-expressing cell differentiation in initially developed taste buds and taste organoids. Cell Tissue Res 2023:10.1007/s00441-023-03756-8. [PMID: 36781481 DOI: 10.1007/s00441-023-03756-8] [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: 08/09/2022] [Accepted: 01/30/2023] [Indexed: 02/15/2023]
Abstract
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.
Collapse
Affiliation(s)
- Kae Matsuyama
- Division of Anatomy, Department of Health Promotion, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, 803-8580, Japan.
| | - Shingo Takai
- Section of Oral Neuroscience, Graduate School of Dental Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan
| | - Noriatsu Shigemura
- Section of Oral Neuroscience, Graduate School of Dental Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan.,Research and Development Center for Five-Sense Devices, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
| | - Mitsushiro Nakatomi
- Department of Human, Information and Life Sciences, School of Health Sciences, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishi-ku, Kitakyushu, 807-8555, Japan
| | - Tatsuo Kawamoto
- Division of Orofacial Functions and Orthodontics, Department of Health Promotion, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, 803-8580, Japan
| | - Shinji Kataoka
- Division of Anatomy, Department of Health Promotion, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, 803-8580, Japan
| | - Takashi Toyono
- Division of Anatomy, Department of Health Promotion, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, 803-8580, Japan
| | - Yuji Seta
- Division of Anatomy, Department of Health Promotion, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, 803-8580, Japan
| |
Collapse
|
6
|
Ikuta R, Hamada S. The presynaptic active zone protein Bassoon as a marker for synapses between Type III cells and afferent nerve fibers in taste buds. Chem Senses 2022; 47:6619055. [PMID: 35762653 DOI: 10.1093/chemse/bjac016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Taste buds are receptor organs for gustation. Two types of taste receptor cells have been identified in taste buds: Type II and Type III cells. Type III cells connect with afferent fibers through conventional chemical synapses. In the present study, we used immunocytochemistry to examine the distribution pattern of Bassoon, a scaffolding protein of the cytomatrix at the active zones of conventional synapses in mouse taste buds. Bassoon was predominantly detected as small puncta in Type III cells. Bassoon-immunoreactive puncta were observed in proximity to or partially overlapping with intragemmal nerve fibers. The distribution pattern of Bassoon in taste buds was similar among circumvallate, fungiform, and foliate taste buds. Immunoelectron microscopy showed Bassoon at the active zones of the conventional synapses of Type III cells in circumvallate taste buds. The present results demonstrate that Bassoon is a marker for synapses between Type III cells and afferent fibers in mouse taste buds.
Collapse
Affiliation(s)
- Rio Ikuta
- Department of Food and Health Sciences, International College of Arts and Sciences, Fukuoka Women's University, 1-1-1, Kasumigaoka, Higashi-ku, Fukuoka 813-8529, Japan
| | - Shun Hamada
- Department of Food and Health Sciences, International College of Arts and Sciences, Fukuoka Women's University, 1-1-1, Kasumigaoka, Higashi-ku, Fukuoka 813-8529, Japan
| |
Collapse
|
7
|
Finger T, Kinnamon S. Purinergic neurotransmission in the gustatory system. Auton Neurosci 2021; 236:102874. [PMID: 34536906 DOI: 10.1016/j.autneu.2021.102874] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 08/13/2021] [Accepted: 08/22/2021] [Indexed: 11/26/2022]
Abstract
Taste buds consist of specialized epithelial cells which detect particular tastants and synapse onto the afferent taste nerve innervating the endorgan. The nature of the neurotransmitter released by taste cells onto the nerve fiber was enigmatic early in this century although neurotransmitters for other sensory receptor cell types, e.g. hair cells, photoreceptors, was known for at least a decade. A 1999 paper by Burnstock and co-workers (Bo et al., 1999) showing the presence of P2X receptors on the afferent nerves served as a springboard for research that ultimately led to the discovery of ATP as the crucial neurotransmitter in the taste system (Finger et al., 2005). Subsequent work showed that a subpopulation of taste cells utilize a unique release channel, CALHM1/3, to release ATP in a voltage-dependent manner. Despite these advances, several aspects of purinergic transmission in this system remain to be elucidated.
Collapse
Affiliation(s)
- T Finger
- Dept. Cell & Developmental Biology, Dept. Otolaryngology, Univ. Colorado School of Medicine, Anschutz Medical Campus, MS 8108, Room L18-11118, RC-1, 12801 E. 17th Ave., Aurora, CO 80045, United States of America.
| | - Sue Kinnamon
- Dept. Cell & Developmental Biology, Dept. Otolaryngology, Univ. Colorado School of Medicine, Anschutz Medical Campus, MS 8108, Room L18-11118, RC-1, 12801 E. 17th Ave., Aurora, CO 80045, United States of America
| |
Collapse
|
8
|
Ogata T, Ohtubo Y. Quantitative Analysis of Taste Bud Cell Numbers in the Circumvallate and Foliate Taste Buds of Mice. Chem Senses 2021; 45:261-273. [PMID: 32157267 DOI: 10.1093/chemse/bjaa017] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
A mouse single taste bud contains 10-100 taste bud cells (TBCs) in which the elongated TBCs are classified into 3 cell types (types I-III) equipped with different taste receptors. Accordingly, differences in the cell numbers and ratios of respective cell types per taste bud may affect taste-nerve responsiveness. Here, we examined the numbers of each immunoreactive cell for the type II (sweet, bitter, or umami receptor cells) and type III (sour and/or salt receptor cells) markers per taste bud in the circumvallate and foliate papillae and compared these numerical features of TBCs per taste bud to those in fungiform papilla and soft palate, which we previously reported. In circumvallate and foliate taste buds, the numbers of TBCs and immunoreactive cells per taste bud increased as a linear function of the maximal cross-sectional taste bud area. Type II cells made up approximately 25% of TBCs irrespective of the regions from which the TBCs arose. In contrast, type III cells in circumvallate and foliate taste buds made up approximately 11% of TBCs, which represented almost 2 times higher than what was observed in the fungiform and soft palate taste buds. The densities (number of immunoreactive cells per taste bud divided by the maximal cross-sectional area of the taste bud) of types II and III cells per taste bud are significantly higher in the circumvallate papillae than in the other regions. The effects of these region-dependent differences on the taste response of the taste bud are discussed.
Collapse
Affiliation(s)
- Takahiro Ogata
- Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, Hibikino 2-4, Kitakyushu-shi, Japan.,ASTEC Co., Ltd, Minamizato 4-6-15, Shime-machi, Kasuya-gun, Fukuoka, Japan
| | - Yoshitaka Ohtubo
- Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, Hibikino 2-4, Kitakyushu-shi, Japan
| |
Collapse
|
9
|
Hsu CC, Seta Y, Matsuyama K, Kataoka S, Nakatomi M, Toyono T, Gunjigake KK, Kuroishi KN, Kawamoto T. Mash1-expressing cells may be relevant to type III cells and a subset of PLCβ2-positive cell differentiation in adult mouse taste buds. Cell Tissue Res 2020; 383:667-675. [PMID: 32960355 DOI: 10.1007/s00441-020-03283-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 08/14/2020] [Indexed: 11/28/2022]
Abstract
Mammalian taste bud cells have a limited lifespan and differentiate into type I, II, and III cells from basal cells (type IV cells) (postmitotic precursor cells). However, little is known regarding the cell lineage within taste buds. In this study, we investigated the cell fate of Mash1-positive precursor cells utilizing the Cre-loxP system to explore the differentiation of taste bud cells. We found that Mash1-expressing cells in Ascl1CreERT2::CAG-floxed tdTomato mice differentiated into taste bud cells that expressed aromatic L-amino acid decarboxylase (AADC) and carbonic anhydrase IV (CA4) (type III cell markers), but did not differentiate into most of gustducin (type II cell marker)-positive cells. Additionally, we found that Mash1-expressing cells could differentiate into phospholipase C β2 (PLCβ2)-positive cells, which have a shorter lifespan compared with AADC- and CA4-positive cells. These results suggest that Mash1-positive precursor cells could differentiate into type III cells, but not into most of type II cells, in the taste buds.
Collapse
Affiliation(s)
- Chia-Chien Hsu
- Division of Orofacial Functions and Orthodontics, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, 803-8580, Japan.,Division of Anatomy, Department of Health Improvement, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, 803-8580, Japan
| | - Yuji Seta
- Division of Anatomy, Department of Health Improvement, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, 803-8580, Japan.
| | - Kae Matsuyama
- Division of Anatomy, Department of Health Improvement, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, 803-8580, Japan
| | - Shinji Kataoka
- Division of Anatomy, Department of Health Improvement, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, 803-8580, Japan
| | - Mitsushiro Nakatomi
- Division of Anatomy, Department of Health Improvement, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, 803-8580, Japan
| | - Takashi Toyono
- Division of Anatomy, Department of Health Improvement, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, 803-8580, Japan
| | - Kaori K Gunjigake
- Division of Orofacial Functions and Orthodontics, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, 803-8580, Japan
| | - Kayoko N Kuroishi
- Division of Orofacial Functions and Orthodontics, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, 803-8580, Japan
| | - Tatsuo Kawamoto
- Division of Orofacial Functions and Orthodontics, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, 803-8580, Japan
| |
Collapse
|
10
|
Sukumaran SK, Lewandowski BC, Qin Y, Kotha R, Bachmanov AA, Margolskee RF. Whole transcriptome profiling of taste bud cells. Sci Rep 2017; 7:7595. [PMID: 28790351 PMCID: PMC5548921 DOI: 10.1038/s41598-017-07746-z] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Accepted: 07/03/2017] [Indexed: 12/15/2022] Open
Abstract
Analysis of single-cell RNA-Seq data can provide insights into the specific functions of individual cell types that compose complex tissues. Here, we examined gene expression in two distinct subpopulations of mouse taste cells: Tas1r3-expressing type II cells and physiologically identified type III cells. Our RNA-Seq libraries met high quality control standards and accurately captured differential expression of marker genes for type II (e.g. the Tas1r genes, Plcb2, Trpm5) and type III (e.g. Pkd2l1, Ncam, Snap25) taste cells. Bioinformatics analysis showed that genes regulating responses to stimuli were up-regulated in type II cells, while pathways related to neuronal function were up-regulated in type III cells. We also identified highly expressed genes and pathways associated with chemotaxis and axon guidance, providing new insights into the mechanisms underlying integration of new taste cells into the taste bud. We validated our results by immunohistochemically confirming expression of selected genes encoding synaptic (Cplx2 and Pclo) and semaphorin signalling pathway (Crmp2, PlexinB1, Fes and Sema4a) components. The approach described here could provide a comprehensive map of gene expression for all taste cell subpopulations and will be particularly relevant for cell types in taste buds and other tissues that can be identified only by physiological methods.
Collapse
Affiliation(s)
- Sunil K Sukumaran
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA, 19104, USA
| | - Brian C Lewandowski
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA, 19104, USA
| | - Yumei Qin
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA, 19104, USA.,College of Food & Biology Engineering, Zhejiang Gongshang University, Hangzhou, 310018, P.R. China
| | - Ramana Kotha
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA, 19104, USA
| | | | - Robert F Margolskee
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA, 19104, USA.
| |
Collapse
|
11
|
Abstract
The past decade has witnessed a consolidation and refinement of the extraordinary progress made in taste research. This Review describes recent advances in our understanding of taste receptors, taste buds, and the connections between taste buds and sensory afferent fibres. The article discusses new findings regarding the cellular mechanisms for detecting tastes, new data on the transmitters involved in taste processing and new studies that address longstanding arguments about taste coding.
Collapse
|
12
|
Honma S, Kadono K, Kawano A, Wakisaka S. Immunohistochemical localization of SNARE core proteins in intrapulpal and intradentinal nerve fibers of rat molar teeth. Arch Oral Biol 2017; 73:248-252. [DOI: 10.1016/j.archoralbio.2016.10.025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Revised: 10/15/2016] [Accepted: 10/24/2016] [Indexed: 11/29/2022]
|
13
|
Amiloride-Insensitive Salt Taste Is Mediated by Two Populations of Type III Taste Cells with Distinct Transduction Mechanisms. J Neurosci 2016; 36:1942-53. [PMID: 26865617 DOI: 10.1523/jneurosci.2947-15.2016] [Citation(s) in RCA: 87] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
UNLABELLED Responses in the amiloride-insensitive (AI) pathway, one of the two pathways mediating salty taste in mammals, are modulated by the size of the anion of a salt. This "anion effect" has been hypothesized to result from inhibitory transepithelial potentials (TPs) generated across the lingual epithelium as cations permeate through tight junctions and leave their larger and less permeable anions behind (Ye et al., 1991). We tested directly the necessity of TPs for the anion effect by measuring responses to NaCl and Na-gluconate (small and large anion sodium salts, respectively) in isolated taste cells from mouse circumvallate papillae. Using calcium imaging, we identified AI salt-responsive type III taste cells and demonstrated that they compose a subpopulation of acid-responsive taste cells. Even in the absence of TPs, many (66%) AI salt-responsive type III taste cells still exhibited the anion effect, demonstrating that some component of the transduction machinery for salty taste in type III cells is sensitive to anion size. We hypothesized that osmotic responses could explain why a minority of type III cells (34%) had AI salt responses but lacked anion sensitivity. All AI type III cells had osmotic responses to cellobiose, which were significantly modulated by extracellular sodium concentration, suggesting the presence of a sodium-conducting osmotically sensitive ion channel. However, these responses were significantly larger in AI type III cells that did not exhibit the anion effect. These findings indicate that multiple mechanisms could underlie AI salt responses in type III taste cells, one of which may contribute to the anion effect. SIGNIFICANCE STATEMENT Understanding the mechanisms underlying salty taste will help inform strategies to combat the health problems associated with NaCl overconsumption by humans. Of the two pathways underlying salty taste in mammals, the amiloride-insensitive (AI) pathway is the least understood. Using calcium imaging of isolated mouse taste cells, we identify two separate populations of AI salt-responsive type III taste cells distinguished by their sensitivity to anion size and show that these cells compose subpopulations of acid-responsive taste cells. We also find evidence that a sodium-conducting osmotically sensitive mechanism contributes to salt responses in type III taste cells. Our data not only provide new insights into the transduction mechanisms of AI salt taste but also have important implications for general theories of taste encoding.
Collapse
|
14
|
Abstract
The sense of taste, or gustation, is mediated by taste buds, which are housed in specialized taste papillae found in a stereotyped pattern on the surface of the tongue. Each bud, regardless of its location, is a collection of ∼100 cells that belong to at least five different functional classes, which transduce sweet, bitter, salt, sour and umami (the taste of glutamate) signals. Taste receptor cells harbor functional similarities to neurons but, like epithelial cells, are rapidly and continuously renewed throughout adult life. Here, I review recent advances in our understanding of how the pattern of taste buds is established in embryos and discuss the cellular and molecular mechanisms governing taste cell turnover. I also highlight how these findings aid our understanding of how and why many cancer therapies result in taste dysfunction.
Collapse
Affiliation(s)
- Linda A Barlow
- Department of Cell and Developmental Biology, Graduate Program in Cell Biology, Stem Cells and Development and the Rocky Mountain Taste and Smell Center, University of Colorado, School Medicine, Anschutz Medical Campus, Aurora, CO 80045, USA
| |
Collapse
|
15
|
Recent Advances in Molecular Mechanisms of Taste Signaling and Modifying. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2016; 323:71-106. [PMID: 26944619 DOI: 10.1016/bs.ircmb.2015.12.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The sense of taste conveys crucial information about the quality and nutritional value of foods before it is ingested. Taste signaling begins with taste cells via taste receptors in oral cavity. Activation of these receptors drives the transduction systems in taste receptor cells. Then particular transmitters are released from the taste cells and activate corresponding afferent gustatory nerve fibers. Recent studies have revealed that taste sensitivities are defined by distinct taste receptors and modulated by endogenous humoral factors in a specific group of taste cells. Such peripheral taste generations and modifications would directly influence intake of nutritive substances. This review will highlight current understanding of molecular mechanisms for taste reception, signal transduction in taste bud cells, transmission between taste cells and nerves, regeneration from taste stem cells, and modification by humoral factors at peripheral taste organs.
Collapse
|
16
|
Kurokawa A, Narukawa M, Ohmoto M, Yoshimoto J, Abe K, Misaka T. Expression of the synaptic exocytosis-regulating molecule complexin 2 in taste buds and its participation in peripheral taste transduction. J Neurochem 2015; 133:806-14. [PMID: 25692331 PMCID: PMC6680196 DOI: 10.1111/jnc.13073] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Revised: 01/04/2015] [Accepted: 02/04/2015] [Indexed: 11/30/2022]
Abstract
Taste information from type III taste cells to gustatory neurons is thought to be transmitted via synapses. However, the molecular mechanisms underlying taste transduction through this pathway have not been fully elucidated. In this study, to identify molecules that participate in synaptic taste transduction, we investigated whether complexins (Cplxs), which play roles in regulating membrane fusion in synaptic vesicle exocytosis, were expressed in taste bud cells. Among four Cplx isoforms, strong expression of Cplx2 mRNA was detected in type III taste cells. To investigate the function of CPLX2 in taste transduction, we observed taste responses in CPLX2‐knockout mice. When assessed with electrophysiological and behavioral assays, taste responses to some sour stimuli in CPLX2‐knockout mice were significantly lower than those in wild‐type mice. These results suggested that CPLX2 participated in synaptic taste transduction from type III taste cells to gustatory neurons.
A part of taste information is thought to be transmitted via synapses. However, the molecular mechanisms have not been fully elucidated. To identify molecules that participate in synaptic taste transduction, we investigated complexins (Cplxs) expression in taste bud cells. Strong expression of Cplx2 mRNA was detected in taste bud cells. Furthermore, taste responses to some sour stimuli in CPLX2‐ knockout mice were significantly lower than those in wild‐type mice. These suggested that CPLX2 participated in synaptic taste transduction.
Collapse
Affiliation(s)
- Azusa Kurokawa
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Masataka Narukawa
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Makoto Ohmoto
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Joto Yoshimoto
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Keiko Abe
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.,Kanagawa Academy of Science and Technology, Kanagawa, Japan
| | - Takumi Misaka
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| |
Collapse
|
17
|
Kimura K, Ohtubo Y, Tateno K, Takeuchi K, Kumazawa T, Yoshii K. Cell-type-dependent action potentials and voltage-gated currents in mouse fungiform taste buds. Eur J Neurosci 2013; 39:24-34. [PMID: 24152110 DOI: 10.1111/ejn.12388] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Accepted: 09/11/2013] [Indexed: 01/24/2023]
Abstract
Taste receptor cells fire action potentials in response to taste substances to trigger non-exocytotic neurotransmitter release in type II cells and exocytotic release in type III cells. We investigated possible differences between these action potentials fired by mouse taste receptor cells using in situ whole-cell recordings, and subsequently we identified their cell types immunologically with cell-type markers, an IP3 receptor (IP3 R3) for type II cells and a SNARE protein (SNAP-25) for type III cells. Cells not immunoreactive to these antibodies were examined as non-IRCs. Here, we show that type II cells and type III cells fire action potentials using different ionic mechanisms, and that non-IRCs also fire action potentials with either of the ionic mechanisms. The width of action potentials was significantly narrower and their afterhyperpolarization was deeper in type III cells than in type II cells. Na(+) current density was similar in type II cells and type III cells, but it was significantly smaller in non-IRCs than in the others. Although outwardly rectifying current density was similar between type II cells and type III cells, tetraethylammonium (TEA) preferentially suppressed the density in type III cells and the majority of non-IRCs. Our mathematical model revealed that the shape of action potentials depended on the ratio of TEA-sensitive current density and TEA-insensitive current one. The action potentials of type II cells and type III cells under physiological conditions are discussed.
Collapse
Affiliation(s)
- Kenji Kimura
- Graduate school of Life Science and Systems Engineering, Kyushu Institute of Technology, Hibikino 2-4, Kitakyushu-shi, 808-0196, Japan
| | | | | | | | | | | |
Collapse
|
18
|
Sugita M, Yamamoto K, Hirono C, Shiba Y. Functional dissection of sweet and bitter taste pathways. J Oral Biosci 2013. [DOI: 10.1016/j.job.2013.02.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
|
19
|
Kotani T, Toyono T, Seta Y, Kitou A, Kataoka S, Toyoshima K. Expression of synaptogyrin-1 in T1R2-expressing type II taste cells and type III taste cells of rat circumvallate taste buds. Cell Tissue Res 2013; 353:391-8. [DOI: 10.1007/s00441-013-1629-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Accepted: 03/14/2013] [Indexed: 11/28/2022]
|
20
|
Abstract
Taste buds are found in a distributed array on the tongue surface, and are innervated by cranial nerves that convey taste information to the brain. For nearly a century, taste buds were thought to be induced by nerves late in embryonic development. However, this view has shifted dramatically. A host of studies now indicate that taste bud development is initiated and proceeds via processes that are nerve-independent, occur long before birth, and governed by cellular and molecular mechanisms intrinsic to the developing tongue. Here we review the state of our understanding of the molecular and cellular regulation of taste bud development, incorporating important new data obtained through the use of two powerful genetic systems, mouse and zebrafish.
Collapse
|
21
|
|
22
|
Immunocytochemical analysis of P2X2 in rat circumvallate taste buds. BMC Neurosci 2012; 13:51. [PMID: 22621423 PMCID: PMC3507709 DOI: 10.1186/1471-2202-13-51] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Accepted: 04/20/2012] [Indexed: 11/23/2022] Open
Abstract
Background Our laboratory has shown that classical synapses and synaptic proteins are associated with Type III cells. Yet it is generally accepted that Type II cells transduce bitter, sweet and umami stimuli. No classical synapses, however, have been found associated with Type II cells. Recent studies indicate that the ionotropic purinergic receptors P2X2/P2X3 are present in rodent taste buds. Taste nerve processes express the ionotropic purinergic receptors (P2X2/P2X3). P2X2/P2X3Dbl−/− mice are not responsive to sweet, umami and bitter stimuli, and it has been proposed that ATP acts as a neurotransmitter in taste buds. The goal of the present study is to learn more about the nature of purinergic contacts in rat circumvallate taste buds by examining immunoreactivity to antisera directed against the purinergic receptor P2X2. Results P2X2-like immunoreactivity is present in intragemmal nerve processes in rat circumvallate taste buds. Intense immunoreactivity can also be seen in the subgemmal nerve plexuses located below the basal lamina. The P2X2 immunoreactive nerve processes also display syntaxin-1-LIR. The immunoreactive nerves are in close contact with the IP3R3-LIR Type II cells and syntaxin-1-LIR and/or 5-HT-LIR Type III cells. Taste cell synapses are observed only from Type III taste cells onto P2X2-LIR nerve processes. Unusually large, “atypical” mitochondria in the Type II taste cells are found only at close appositions with P2X2-LIR nerve processes. P2X2 immunogold particles are concentrated at the membranes of nerve processes at close appositions with taste cells. Conclusions Based on our immunofluorescence and immunoelectron microscopical studies we believe that both perigemmal and most all intragemmal nerve processes display P2X2-LIR. Moreover, colloidal gold immunoelectron microscopy indicates that P2X2-LIR in nerve processes is concentrated at sites of close apposition with Type II cells. This supports the hypothesis that ATP may be a key neurotransmitter in taste transduction and that Type II cells release ATP, activating P2X2 receptors in nerve processes.
Collapse
|
23
|
Ohtubo Y, Iwamoto M, Yoshii K. Subtype-dependent postnatal development of taste receptor cells in mouse fungiform taste buds. Eur J Neurosci 2012; 35:1661-71. [PMID: 22462540 DOI: 10.1111/j.1460-9568.2012.08068.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Taste buds contain two types of taste receptor cells, inositol 1,4,5-triphosphate receptor type 3-immunoreactive cells (type II cells) and synaptosomal-associating protein-25-immunoreactive cells (type III cells). We investigated their postnatal development in mouse fungiform taste buds immunohistochemically and electrophysiologically. The cell density, i.e. the number of cells per taste bud divided by the maximal area of the horizontal cross-section of the taste bud, of type II cells increased by postnatal day (PD)49, where as that of type III cells was unchanged throughout the postnatal observation period and was equal to that of the adult cells at PD1. The immunoreactivity of taste bud cell subtypes was the same as that of their respective subtypes in adult mice throughout the postnatal observation period. Almost all type II cells were immunoreactive to gustducin at PD1, and then the ratio of gustducin-immunoreactive type II cells to all type II cells decreased to a saturation level, ∼60% of all type II cells, by PD15. Type II and III cells generated voltage-gated currents similar to their respective adult cells even at PD3. These results show that infant taste receptor cells are as excitable as those of adults and propagate in a subtype-dependent manner. The relationship between the ratio of each taste receptor cell subtype to all cells and taste nerve responses are discussed.
Collapse
Affiliation(s)
- Yoshitaka Ohtubo
- Kyushu Institute of Technology, Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, Kitakyushu, Japan
| | | | | |
Collapse
|
24
|
|
25
|
Shin YK, Cong WN, Cai H, Kim W, Maudsley S, Egan JM, Martin B. Age-related changes in mouse taste bud morphology, hormone expression, and taste responsivity. J Gerontol A Biol Sci Med Sci 2011; 67:336-44. [PMID: 22056740 DOI: 10.1093/gerona/glr192] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Normal aging is a complex process that affects every organ system in the body, including the taste system. Thus, we investigated the effects of the normal aging process on taste bud morphology, function, and taste responsivity in male mice at 2, 10, and 18 months of age. The 18-month-old animals demonstrated a significant reduction in taste bud size and number of taste cells per bud compared with the 2- and 10-month-old animals. The 18-month-old animals exhibited a significant reduction of protein gene product 9.5 and sonic hedgehog immunoreactivity (taste cell markers). The number of taste cells expressing the sweet taste receptor subunit, T1R3, and the sweet taste modulating hormone, glucagon-like peptide-1, were reduced in the 18-month-old mice. Concordant with taste cell alterations, the 18-month-old animals demonstrated reduced sweet taste responsivity compared with the younger animals and the other major taste modalities (salty, sour, and bitter) remained intact.
Collapse
Affiliation(s)
- Yu-Kyong Shin
- Laboratory of Clinical Investigation, Diabetes Section, National Institute on Aging, Baltimore, MD 21224, USA
| | | | | | | | | | | | | |
Collapse
|
26
|
Affiliation(s)
- Albertino Bigiani
- Dipartimento di Scienze Biomediche, Sezione di Fisiologia; Università di Modena e Reggio Emilia; Modena, via G. Campi 287; 41125; Modena; Italy
| | - Simone Prandi
- Dipartimento di Scienze Biomediche, Sezione di Fisiologia; Università di Modena e Reggio Emilia; Modena, via G. Campi 287; 41125; Modena; Italy
| |
Collapse
|
27
|
Gaillard D, Barlow LA. Taste bud cells of adult mice are responsive to Wnt/β-catenin signaling: implications for the renewal of mature taste cells. Genesis 2011; 49:295-306. [PMID: 21328519 DOI: 10.1002/dvg.20731] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2010] [Revised: 01/28/2011] [Accepted: 02/02/2011] [Indexed: 12/11/2022]
Abstract
Wnt/β-catenin signaling initiates taste papilla development in mouse embryos, however, its involvement in taste cell turnover in adult mice has not been explored. Here we used the BATGAL reporter mouse model, which carries an engineered allele in which the LacZ gene is expressed in the presence of activated β-catenin, to determine the responsiveness of adult taste bud cells to canonical Wnt signaling. Double immunostaining with markers of differentiated taste cells revealed that a subset of Type I, II, and III taste cells express β-galactosidase. Using in situ hybridization, we showed that β-catenin activates the transcription of the LacZ gene mainly in intragemmal basal cells that are immature taste cells, identified by their expression of Sonic Hedgehog (Shh). Finally, we showed that β-catenin activity is significantly reduced in taste buds of 25-week-old mice compared with 10-week-old animals. Our data suggest that Wnt/β-catenin signaling may influence taste cell turnover by regulating cell differentiation. Reduced canonical Wnt signaling in older mice could explain in part the loss of taste sensitivity with aging, implicating a possible deficiency in the rate of taste cell renewal. More investigations are now necessary to understand if and how Wnt signaling regulates adult taste cell turnover.
Collapse
Affiliation(s)
- Dany Gaillard
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, USA.
| | | |
Collapse
|
28
|
Medler KF. Multiple Roles for TRPs in the Taste System: Not Your Typical TRPs. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011; 704:831-46. [DOI: 10.1007/978-94-007-0265-3_43] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
|
29
|
Abstract
Exocytosis, consisting of the merger of vesicle and plasma membrane, is a common mechanism used by different types of nucleated cells to release their vesicular contents. Taste cells possess vesicles containing various neurotransmitters to communicate with adjacent taste cells and afferent nerve fibers. However, whether these vesicles engage in exocytosis on a stimulus is not known. Since vesicle membrane merger with the plasma membrane is reflected in plasma membrane area fluctuations, we measured membrane capacitance (C(m)), a parameter linearly related to membrane surface area. To investigate whether taste cells undergo regulated exocytosis, we used the compensated tight-seal whole-cell recording technique to monitor depolarization-induced changes in C(m) in the different types of taste cells. To identify taste cell types, mice expressing green fluorescent protein from the TRPM5 promoter or from the GAD67 promoter were used to discriminate type II and type III taste cells, respectively. Moreover, the cell types were also identified by monitoring their voltage-current properties. The results demonstrate that only type III taste cells show significant depolarization-induced increases in C(m), which were correlated to the voltage-activated calcium currents. The results suggest that type III, but neither type II nor type I cells exhibit depolarization-induced regulated exocytosis to release transmitter and activate gustatory afferent nerve fibers.
Collapse
|
30
|
Ohtubo Y, Yoshii K. Quantitative analysis of taste bud cell numbers in fungiform and soft palate taste buds of mice. Brain Res 2010; 1367:13-21. [PMID: 20971092 DOI: 10.1016/j.brainres.2010.10.060] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2010] [Revised: 10/14/2010] [Accepted: 10/14/2010] [Indexed: 10/18/2022]
Abstract
Mammalian taste bud cells (TBCs) consist of several cell types equipped with different taste receptor molecules, and hence the ratio of cell types in a taste bud constitutes the taste responses of the taste bud. Here we show that the population of immunohistochemically identified cell types per taste bud is proportional to the number of total TBCs in the taste bud or the area of the taste bud in fungiform papillae, and that the proportions differ among cell types. This result is applicable to soft palate taste buds. However, the density of almost all cell types, the population of cell types divided by the area of the respective taste buds, is significantly higher in soft palates. These results suggest that the turnover of TBCs is regulated to keep the ratio of each cell type constant, and that taste responsiveness is different between fungiform and soft palate taste buds.
Collapse
Affiliation(s)
- Yoshitaka Ohtubo
- Kyushu Institute of Technology, Hibikino 2-4, Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, Kitakyushu 808-0196, Japan.
| | | |
Collapse
|
31
|
Shin YK, Martin B, Kim W, White CM, Ji S, Sun Y, Smith RG, Sévigny J, Tschöp MH, Maudsley S, Egan JM. Ghrelin is produced in taste cells and ghrelin receptor null mice show reduced taste responsivity to salty (NaCl) and sour (citric acid) tastants. PLoS One 2010; 5:e12729. [PMID: 20856820 PMCID: PMC2939079 DOI: 10.1371/journal.pone.0012729] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2010] [Accepted: 08/11/2010] [Indexed: 12/14/2022] Open
Abstract
Background The gustatory system plays a critical role in determining food preferences, food intake and energy balance. The exact mechanisms that fine tune taste sensitivity are currently poorly defined, but it is clear that numerous factors such as efferent input and specific signal transduction cascades are involved. Methodology/Principal Findings Using immunohistochemical analyses, we show that ghrelin, a hormone classically considered to be an appetite-regulating hormone, is present within the taste buds of the tongue. Prepro-ghrelin, prohormone convertase 1/3 (PC 1/3), ghrelin, its cognate receptor (GHSR), and ghrelin-O-acyltransferase (GOAT , the enzyme that activates ghrelin) are expressed in Type I, II, III and IV taste cells of mouse taste buds. In addition, ghrelin and GHSR co-localize in the same taste cells, suggesting that ghrelin works in an autocrine manner in taste cells. To determine a role for ghrelin in modifying taste perception, we performed taste behavioral tests using GHSR null mice. GHSR null mice exhibited significantly reduced taste responsivity to sour (citric acid) and salty (sodium chloride) tastants. Conclusions/Significance These findings suggest that ghrelin plays a local modulatory role in determining taste bud signaling and function and could be a novel mechanism for the modulation of salty and sour taste responsivity.
Collapse
Affiliation(s)
- Yu-Kyong Shin
- National Institute on Aging/National Institutes of Health, Baltimore, Maryland, United States of America
| | - Bronwen Martin
- National Institute on Aging/National Institutes of Health, Baltimore, Maryland, United States of America
| | - Wook Kim
- National Institute on Aging/National Institutes of Health, Baltimore, Maryland, United States of America
| | - Caitlin M. White
- National Institute on Aging/National Institutes of Health, Baltimore, Maryland, United States of America
| | - Sunggoan Ji
- National Institute on Aging/National Institutes of Health, Baltimore, Maryland, United States of America
| | - Yuxiang Sun
- Huffington Center on Aging, Baylor College of Medicine, Houston, Texas, United States of America
| | - Roy G. Smith
- Department of Metabolism and Aging, The Scripps Research Institute, Scripps Florida, Jupiter, Florida, United States of America
| | - Jean Sévigny
- Centre de Recherche en Rhumatologie et Immunologie, Centre Hospitalier Universitaire de Québec, Université Laval, Québec City, Québec, Canada
| | - Matthias H. Tschöp
- Division of Endocrinology, Departments of Medicine and Psychiatry, Metabolic Diseases Institute, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Stuart Maudsley
- National Institute on Aging/National Institutes of Health, Baltimore, Maryland, United States of America
| | - Josephine M. Egan
- National Institute on Aging/National Institutes of Health, Baltimore, Maryland, United States of America
- * E-mail:
| |
Collapse
|
32
|
Martin B, Shin YK, White CM, Ji S, Kim W, Carlson OD, Napora JK, Chadwick W, Chapter M, Waschek JA, Mattson MP, Maudsley S, Egan JM. Vasoactive intestinal peptide-null mice demonstrate enhanced sweet taste preference, dysglycemia, and reduced taste bud leptin receptor expression. Diabetes 2010; 59:1143-52. [PMID: 20150284 PMCID: PMC2857894 DOI: 10.2337/db09-0807] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
OBJECTIVE It is becoming apparent that there is a strong link between taste perception and energy homeostasis. Recent evidence implicates gut-related hormones in taste perception, including glucagon-like peptide 1 and vasoactive intestinal peptide (VIP). We used VIP knockout mice to investigate VIP's specific role in taste perception and connection to energy regulation. RESEARCH DESIGN AND METHODS Body weight, food intake, and plasma levels of multiple energy-regulating hormones were measured and pancreatic morphology was determined. In addition, the immunocytochemical profile of taste cells and gustatory behavior were examined in wild-type and VIP knockout mice. RESULTS VIP knockout mice demonstrate elevated plasma glucose, insulin, and leptin levels, with no islet beta-cell number/topography alteration. VIP and its receptors (VPAC1, VPAC2) were identified in type II taste cells of the taste bud, and VIP knockout mice exhibit enhanced taste preference to sweet tastants. VIP knockout mouse taste cells show a significant decrease in leptin receptor expression and elevated expression of glucagon-like peptide 1, which may explain sweet taste preference of VIP knockout mice. CONCLUSIONS This study suggests that the tongue can play a direct role in modulating energy intake to correct peripheral glycemic imbalances. In this way, we could view the tongue as a sensory mechanism that is bidirectionally regulated and thus forms a bridge between available foodstuffs and the intricate hormonal balance in the animal itself.
Collapse
Affiliation(s)
- Bronwen Martin
- National Institutes of Health, National Institute on Aging, Baltimore, Maryland
| | - Yu-Kyong Shin
- National Institutes of Health, National Institute on Aging, Baltimore, Maryland
| | - Caitlin M. White
- National Institutes of Health, National Institute on Aging, Baltimore, Maryland
| | - Sunggoan Ji
- National Institutes of Health, National Institute on Aging, Baltimore, Maryland
| | - Wook Kim
- National Institutes of Health, National Institute on Aging, Baltimore, Maryland
| | - Olga D. Carlson
- National Institutes of Health, National Institute on Aging, Baltimore, Maryland
| | - Joshua K. Napora
- National Institutes of Health, National Institute on Aging, Baltimore, Maryland
| | - Wayne Chadwick
- National Institutes of Health, National Institute on Aging, Baltimore, Maryland
| | - Megan Chapter
- National Institutes of Health, National Institute on Aging, Baltimore, Maryland
| | - James A. Waschek
- Department of Psychiatry and Behavioral Sciences, Mental Retardation Research Center, Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, Los Angeles, California
| | - Mark P. Mattson
- National Institutes of Health, National Institute on Aging, Baltimore, Maryland
| | - Stuart Maudsley
- National Institutes of Health, National Institute on Aging, Baltimore, Maryland
| | - Josephine M. Egan
- National Institutes of Health, National Institute on Aging, Baltimore, Maryland
- Corresponding author: Josephine Egan,
| |
Collapse
|
33
|
Honma S, Taki K, Lei S, Niwa H, Wakisaka S. Immunohistochemical Localization of SNARE Proteins in Dental Pulp and Periodontal Ligament of the Rat Incisor. Anat Rec (Hoboken) 2010; 293:1070-80. [DOI: 10.1002/ar.21106] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
34
|
Iwatsuki K, Ichikawa R, Hiasa M, Moriyama Y, Torii K, Uneyama H. Identification of the vesicular nucleotide transporter (VNUT) in taste cells. Biochem Biophys Res Commun 2009; 388:1-5. [PMID: 19619506 DOI: 10.1016/j.bbrc.2009.07.069] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2009] [Accepted: 07/15/2009] [Indexed: 10/20/2022]
Abstract
Taste cells are chemosensory epithelial cells that sense distinct taste qualities. It is the type II taste cell that express G-protein coupled receptors to sense either umami, sweet, or bitter compounds. Whereas several reports have suggested involvement of ATP in taste signal transduction, there is a paucity of molecular information about how ATP is stored and being released. The recent discovery of a novel vesicular nucleotide transporter (VNUT) led us to examine whether VNUT exist in the taste tissue where ATP is to be released for taste signal transmission. Here, we report that VNUT is selectively expressed in type II cell but not in type III taste cell. In addition, we show that during taste bud development VNUT expression is always accompanied by the expression of type II taste cell markers. Our results, together with previous studies, strongly suggest that VNUT plays a role in type II taste cell.
Collapse
Affiliation(s)
- Ken Iwatsuki
- Institute of Life Sciences, Ajinomoto Co., Inc., Suzuki-cho, Kawasaki-ku, Kawasaki, Japan.
| | | | | | | | | | | |
Collapse
|
35
|
Roper SD. Parallel processing in mammalian taste buds? Physiol Behav 2009; 97:604-8. [PMID: 19371753 DOI: 10.1016/j.physbeh.2009.04.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2009] [Revised: 03/25/2009] [Accepted: 04/01/2009] [Indexed: 12/22/2022]
Abstract
ROPER, S.D. Parallel processing in mammalian taste buds? Physiol Behav XXX(Y) 000-000, 2009. There is emerging evidence that two parallel lines of gustatory information are generated in taste buds. One pathway leads to higher cortical centers and is involved in discriminating basic taste qualities (sweet, bitter, sour, salty, umami) and perceiving flavors. The other pathway may conduct information involved in physiological reflexes such as swallowing, salivation, and cephalic phase digestion. If this notion is true, the existence of two populations of taste bud cells that have different functional characteristics may lie at the origins of the two pathways. This speculative concept is explored in this review of taste signal processing in mammalian taste buds.
Collapse
Affiliation(s)
- Stephen D Roper
- Department of Physiology & Biophysics and Program in Neuroscience, Miller School of Medicine, University of Miami R430, Miami, FL 33136, USA.
| |
Collapse
|
36
|
Gao N, Lu M, Echeverri F, Laita B, Kalabat D, Williams ME, Hevezi P, Zlotnik A, Moyer BD. Voltage-gated sodium channels in taste bud cells. BMC Neurosci 2009; 10:20. [PMID: 19284629 PMCID: PMC2660338 DOI: 10.1186/1471-2202-10-20] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2008] [Accepted: 03/12/2009] [Indexed: 12/19/2022] Open
Abstract
Background Taste bud cells transmit information regarding the contents of food from taste receptors embedded in apical microvilli to gustatory nerve fibers innervating basolateral membranes. In particular, taste cells depolarize, activate voltage-gated sodium channels, and fire action potentials in response to tastants. Initial cell depolarization is attributable to sodium influx through TRPM5 in sweet, bitter, and umami cells and an undetermined cation influx through an ion channel in sour cells expressing PKD2L1, a candidate sour taste receptor. The molecular identity of the voltage-gated sodium channels that sense depolarizing signals and subsequently initiate action potentials coding taste information to gustatory nerve fibers is unknown. Results We describe the molecular and histological expression profiles of cation channels involved in electrical signal transmission from apical to basolateral membrane domains. TRPM5 was positioned immediately beneath tight junctions to receive calcium signals originating from sweet, bitter, and umami receptor activation, while PKD2L1 was positioned at the taste pore. Using mouse taste bud and lingual epithelial cells collected by laser capture microdissection, SCN2A, SCN3A, and SCN9A voltage-gated sodium channel transcripts were expressed in taste tissue. SCN2A, SCN3A, and SCN9A were expressed beneath tight junctions in subsets of taste cells. SCN3A and SCN9A were expressed in TRPM5 cells, while SCN2A was expressed in TRPM5 and PKD2L1 cells. HCN4, a gene previously implicated in sour taste, was expressed in PKD2L1 cells and localized to cell processes beneath the taste pore. Conclusion SCN2A, SCN3A and SCN9A voltage-gated sodium channels are positioned to sense initial depolarizing signals stemming from taste receptor activation and initiate taste cell action potentials. SCN2A, SCN3A and SCN9A gene products likely account for the tetrodotoxin-sensitive sodium currents in taste receptor cells.
Collapse
Affiliation(s)
- Na Gao
- Senomyx, Inc, 4767 Nexus Centre Drive, San Diego, CA 92121, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
37
|
Gao N, Lu M, Echeverri F, Laita B, Kalabat D, Williams ME, Hevezi P, Zlotnik A, Moyer BD. Voltage-gated sodium channels in taste bud cells. BMC Neurosci 2009. [PMID: 19284629 DOI: 10.1186/1471‐2202‐10‐20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Taste bud cells transmit information regarding the contents of food from taste receptors embedded in apical microvilli to gustatory nerve fibers innervating basolateral membranes. In particular, taste cells depolarize, activate voltage-gated sodium channels, and fire action potentials in response to tastants. Initial cell depolarization is attributable to sodium influx through TRPM5 in sweet, bitter, and umami cells and an undetermined cation influx through an ion channel in sour cells expressing PKD2L1, a candidate sour taste receptor. The molecular identity of the voltage-gated sodium channels that sense depolarizing signals and subsequently initiate action potentials coding taste information to gustatory nerve fibers is unknown. RESULTS We describe the molecular and histological expression profiles of cation channels involved in electrical signal transmission from apical to basolateral membrane domains. TRPM5 was positioned immediately beneath tight junctions to receive calcium signals originating from sweet, bitter, and umami receptor activation, while PKD2L1 was positioned at the taste pore. Using mouse taste bud and lingual epithelial cells collected by laser capture microdissection, SCN2A, SCN3A, and SCN9A voltage-gated sodium channel transcripts were expressed in taste tissue. SCN2A, SCN3A, and SCN9A were expressed beneath tight junctions in subsets of taste cells. SCN3A and SCN9A were expressed in TRPM5 cells, while SCN2A was expressed in TRPM5 and PKD2L1 cells. HCN4, a gene previously implicated in sour taste, was expressed in PKD2L1 cells and localized to cell processes beneath the taste pore. CONCLUSION SCN2A, SCN3A and SCN9A voltage-gated sodium channels are positioned to sense initial depolarizing signals stemming from taste receptor activation and initiate taste cell action potentials. SCN2A, SCN3A and SCN9A gene products likely account for the tetrodotoxin-sensitive sodium currents in taste receptor cells.
Collapse
Affiliation(s)
- Na Gao
- Senomyx, Inc, 4767 Nexus Centre Drive, San Diego, CA 92121, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
38
|
Synaptophysin as a probable component of neurotransmission occurring in taste receptor cells. J Mol Histol 2009; 40:59-70. [DOI: 10.1007/s10735-009-9214-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2008] [Accepted: 02/18/2009] [Indexed: 12/18/2022]
|
39
|
Wang Y, Danilova V, Cragin T, Roberts TW, Koposov A, Hellekant G. The sweet taste quality is linked to a cluster of taste fibers in primates: lactisole diminishes preference and responses to sweet in S fibers (sweet best) chorda tympani fibers of M. fascicularis monkey. BMC PHYSIOLOGY 2009; 9:1. [PMID: 19224647 PMCID: PMC2662785 DOI: 10.1186/1472-6793-9-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/03/2008] [Accepted: 02/18/2009] [Indexed: 11/10/2022]
Abstract
Background Psychophysically, sweet and bitter have long been considered separate taste qualities, evident already to the newborn human. The identification of different receptors for sweet and bitter located on separate cells of the taste buds substantiated this separation. However, this finding leads to the next question: is bitter and sweet also kept separated in the next link from the taste buds, the fibers of the taste nerves? Previous studies in non-human primates, P. troglodytes, C. aethiops, M. mulatta, M. fascicularis and C. jacchus, suggest that the sweet and bitter taste qualities are linked to specific groups of fibers called S and Q fibers. In this study we apply a new sweet taste modifier, lactisole, commercially available as a suppressor of the sweetness of sugars on the human tongue, to test our hypothesis that sweet taste is conveyed in S fibers. Results We first ascertained that lactisole exerted similar suppression of sweetness in M. fascicularis, as reported in humans, by recording their preference of sweeteners and non- sweeteners with and without lactisole in two-bottle tests. The addition of lactisole significantly diminished the preference for all sweeteners but had no effect on the intake of non-sweet compounds or the intake of water. We then recorded the response to the same taste stimuli in 40 single chorda tympani nerve fibers. Comparison between single fiber nerve responses to stimuli with and without lactisole showed that lactisole only suppressed the responses to sweeteners in S fibers. It had no effect on the responses to any other stimuli in all other taste fibers. Conclusion In M. fascicularis, lactisole diminishes the attractiveness of compounds, which taste sweet to humans. This behavior is linked to activity of fibers in the S-cluster. Assuming that lactisole blocks the T1R3 monomer of the sweet taste receptor T1R2/R3, these results present further support for the hypothesis that S fibers convey taste from T1R2/R3 receptors, while the impulse activity in non-S fibers originates from other kinds of receptors. The absence of the effect of lactisole on the faint responses in some S fibers to other stimuli as well as the responses to sweet and non-sweet stimuli in non-S fibers suggest that these responses originate from other taste receptors.
Collapse
Affiliation(s)
- Yiwen Wang
- Department of Physiology and Pharmacology, Medical School, University of Minnesota-Duluth, 1035 University Dr, Duluth, MN 55812, USA.
| | | | | | | | | | | |
Collapse
|
40
|
Roberts CD, Dvoryanchikov G, Roper SD, Chaudhari N. Interaction between the second messengers cAMP and Ca2+ in mouse presynaptic taste cells. J Physiol 2009; 587:1657-68. [PMID: 19221121 DOI: 10.1113/jphysiol.2009.170555] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The second messenger, 3',5'-cyclic adenosine monophosphate (cAMP), is known to be modulated in taste buds following exposure to gustatory and other stimuli. Which taste cell type(s) (Type I/glial-like cells, Type II/receptor cells, or Type III/presynaptic cells) undergo taste-evoked changes of cAMP and what the functional consequences of such changes are remain unknown. Using Fura-2 imaging of isolated mouse vallate taste cells, we explored how elevating cAMP alters Ca(2+) levels in identified taste cells. Stimulating taste buds with forskolin (Fsk; 1 microm) + isobutylmethylxanthine (IBMX; 100 microm), which elevates cellular cAMP, triggered Ca(2+) transients in 38% of presynaptic cells (n = 128). We used transgenic GAD-GFP mice to show that cAMP-triggered Ca(2+) responses occur only in the subset of presynaptic cells that lack glutamic acid decarboxylase 67 (GAD). We never observed cAMP-stimulated responses in receptor cells, glial-like cells or GAD-expressing presynaptic cells. The response to cAMP was blocked by the protein kinase A inhibitor H89 and by removing extracellular Ca(2+). Thus, the response to elevated cAMP is a PKA-dependent influx of Ca(2+). This Ca(2+) influx was blocked by nifedipine (an inhibitor of L-type voltage-gated Ca(2+) channels) but was unperturbed by omega-agatoxin IVA and omega-conotoxin GVIA (P/Q-type and N-type channel inhibitors, respectively). Single-cell RT-PCR on functionally identified presynaptic cells from GAD-GFP mice confirmed the pharmacological analyses: Ca(v)1.2 (an L-type subunit) is expressed in cells that display cAMP-triggered Ca(2+) influx, while Ca(v)2.1 (a P/Q subunit) is expressed in all presynaptic cells, and underlies depolarization-triggered Ca(2+) influx. Collectively, these data demonstrate cross-talk between cAMP and Ca(2+) signalling in a subclass of taste cells that form synapses with gustatory fibres and may integrate tastant-evoked signals.
Collapse
Affiliation(s)
- Craig D Roberts
- Neuroscience Program, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | | | | | | |
Collapse
|
41
|
Wang H, Iguchi N, Rong Q, Zhou M, Ogunkorode M, Inoue M, Pribitkin EA, Bachmanov AA, Margolskee RF, Pfeifer K, Huang L. Expression of the voltage-gated potassium channel KCNQ1 in mammalian taste bud cells and the effect of its null-mutation on taste preferences. J Comp Neurol 2009; 512:384-98. [PMID: 19006182 PMCID: PMC2734193 DOI: 10.1002/cne.21899] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Vertebrate taste buds undergo continual cell turnover. To understand how the gustatory progenitor cells in the stratified lingual epithelium migrate and differentiate into different types of mature taste cells, we sought to identify genes that were selectively expressed in taste cells at different maturation stages. Here we report the expression of the voltage-gated potassium channel KCNQ1 in mammalian taste buds of mouse, rat, and human. Immunohistochemistry and nuclear staining showed that nearly all rodent and human taste cells express this channel. Double immunostaining with antibodies against type II and III taste cell markers validated the presence of KCNQ1 in these two types of cells. Co-localization studies with cytokeratin 14 indicated that KCNQ1 is also expressed in type IV basal precursor cells. Null mutation of the kcnq1 gene in mouse, however, did not alter the gross structure of taste buds or the expression of taste signaling molecules. Behavioral assays showed that the mutant mice display reduced preference to some umami substances, but not to any other taste compounds tested. Gustatory nerve recordings, however, were unable to detect any significant change in the integrated nerve responses of the mutant mice to umami stimuli. These results suggest that although it is expressed in nearly all taste bud cells, the function of KCNQ1 is not required for gross taste bud development or peripheral taste transduction pathways, and the reduced preference of kcnq1-null mice in the behavioral assays may be attributable to the deficiency in the central nervous system or other organs.
Collapse
Affiliation(s)
- Hong Wang
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA 19104, USA
| | - Naoko Iguchi
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA 19104, USA
| | - Qi Rong
- Laboratory of Mammalian Genes and Development, NICHD/NIH 9000, Rockville Pike, Bethesda, MD 20892, USA
| | - Minliang Zhou
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA 19104, USA
| | - Martina Ogunkorode
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA 19104, USA
| | - Masashi Inoue
- Department of Life Science, Tokyo University of Pharmacy and Life Science, 1432-1 Horinouchi, Hachioji, Tokyo, Japan
| | - Edmund A. Pribitkin
- Department of Otolaryngology-Head and Neck Surgery, Thomas Jefferson University, 925 Chestnut Street, Philadelphia, PA 19107, USA
| | | | - Robert F. Margolskee
- Department of Neuroscience, Mount Sinai School of Medicine, 1425 Madison Avenue, New York, NY 10029, USA
| | - Karl Pfeifer
- Laboratory of Mammalian Genes and Development, NICHD/NIH 9000, Rockville Pike, Bethesda, MD 20892, USA
| | - Liquan Huang
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA 19104, USA
| |
Collapse
|
42
|
Lin W, Ogura T, Margolskee RF, Finger TE, Restrepo D. TRPM5-Expressing Solitary Chemosensory Cells Respond to Odorous Irritants. J Neurophysiol 2008; 99:1451-60. [DOI: 10.1152/jn.01195.2007] [Citation(s) in RCA: 118] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Inhaled airborne irritants elicit sensory responses in trigeminal nerves innervating the nasal epithelium, leading to protective reflexes. The sensory mechanisms involved in the detection of odorous irritants are poorly understood. We identified a large population of solitary chemosensory cells expressing the transient receptor potential channel M5 (TRPM5) using transgenic mice where the promoter of TRPM5 drives the expression of green fluorescent protein (GFP). Most of these solitary chemosensory cells lie in the anterior nasal cavity. These GFP-labeled solitary chemosensory cells exhibited immunoreactivity for synaptobrevin-2, a vesicle-associated membrane protein important for synaptic transmission. Concomitantly, we found trigeminal nerve fibers apposed closely to the solitary chemosensory cells, indicating potential transmission of sensory information to trigeminal fibers. In addition, stimulation of the nasal cavity with high concentrations (0.5–5 mM) of a variety of odorants elicited event-related potentials (ERPs) in areas rich in TRPM5-expressing solitary chemosensory cells. Furthermore, odorous chemicals and trigeminal stimuli induced changes in intracellular Ca2+ levels in isolated TRPM5-expressing solitary chemosensory cells in a concentration-dependent manner. Together, our data show that the TRPM5-expressing cells respond to a variety of chemicals at high exposure levels typical of irritants and are positioned in the nasal cavity appropriately to monitor inhaled air quality.
Collapse
|
43
|
Kataoka S, Yang R, Ishimaru Y, Matsunami H, Sévigny J, Kinnamon JC, Finger TE. The candidate sour taste receptor, PKD2L1, is expressed by type III taste cells in the mouse. Chem Senses 2007; 33:243-54. [PMID: 18156604 DOI: 10.1093/chemse/bjm083] [Citation(s) in RCA: 151] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The transient receptor potential channel, PKD2L1, is reported to be a candidate receptor for sour taste based on molecular biological and functional studies. Here, we investigated the expression pattern of PKD2L1-immunoreactivity (IR) in taste buds of the mouse. PKD2L1-IR is present in a few elongate cells in each taste bud as reported previously. The PKD2L1-expressing cells are different from those expressing PLCbeta2, a marker of Type II cells. Likewise PKD2L1-immunoreactive taste cells do not express ecto-ATPase which marks Type I cells. The PKD2L1-positive cells are immunoreactive for neural cell adhesion molecule, serotonin, PGP-9.5 (ubiquitin carboxy-terminal transferase), and chromogranin A, all of which are present in Type III taste cells. At the ultrastructural level, PKD2L1-immunoreactive cells form synapses onto afferent nerve fibers, another feature of Type III taste cells. These results are consistent with the idea that different taste cells in each taste bud perform distinct functions. We suggest that Type III cells are necessary for transduction and/or transmission of information about "sour", but have little or no role in transmission of taste information of other taste qualities.
Collapse
Affiliation(s)
- Shinji Kataoka
- Department of Cell and Developmental Biology, University of Colorado at Denver and Health Science Center, Mail Stop 8108, P.O. Box 6511, Aurora, CO 80045, USA
| | | | | | | | | | | | | |
Collapse
|
44
|
Ogura T, Margolskee RF, Tallini YN, Shui B, Kotlikoff MI, Lin W. Immuno-localization of vesicular acetylcholine transporter in mouse taste cells and adjacent nerve fibers: indication of acetylcholine release. Cell Tissue Res 2007; 330:17-28. [PMID: 17704949 DOI: 10.1007/s00441-007-0470-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2006] [Accepted: 07/11/2007] [Indexed: 10/22/2022]
Abstract
Acetylcholine (ACh) is well established as a neurotransmitter and/or neuromodulator in various organs. Previously, it has been shown by Ogura (J Neurophysiol 87:2643-2649, 2002) that in both physiological and immunohistochemical studies the muscarinic acetylcholine (ACh) receptor is present in taste receptor cells. However, it has not been determined if ACh is released locally from taste receptor cells and/or surrounding nerve fibers. In this study we investigated the sites of ACh release in mouse taste tissue using the antisera against vesicular ACh transporter (VAChT), a key element of ACh-containing vesicles. Our data show that VAChT-immunoreactivity is present in many taste receptor cells, including cells expressing the transient receptor potential channel M5 (TRPM5). In taste cells, VAChT-immunoreactivity was colocalized with the immunoreactivity to choline-acetyltransferase (ChAT), which synthesizes ACh. Additionally, enhanced green fluorescent protein (eGFP) was detected in the taste cells of BAC-transgenic mice, in which eGFP was placed under the control of endogenous ChAT transcriptional regulatory elements (ChAT(BAC)-eGFP mice). Furthermore, many ChAT-immunolabeled taste cells also reacted to an antibody against the vesicle-associated membrane protein synaptobrevin-2. These data suggest that ACh-containing vesicles are present in taste receptor cells and ACh release from taste cells may play a role in autocrine and/or paracrine cell-to-cell communication. In addition, certain nerve fibers surrounding or within taste buds were immunoreactive for the VAChT antibody. Some of these fibers were also immunolabeled with antibody against calcitonin gene-related peptide (CGRP), a marker for trigeminal peptidergic fibers. Thus, functions of taste receptor cells could be modulated by trigeminal fibers via ACh release as well.
Collapse
Affiliation(s)
- Tatsuya Ogura
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, MD 21250, USA.
| | | | | | | | | | | |
Collapse
|
45
|
Abstract
Mammalian taste buds are maintained through continuous cell renewal so that taste bud cells are constantly generated from progenitor cells throughout life. Taste bud cells are composed of basal cells and elongated cells. Elongated cells are derived from basal cells and contain taste receptor cells (TRC). Morphologically, elongated cells consist of three distinct types of cells: Types I, II and III. In contrast to the remarkable progress in understanding of the molecular basis for taste reception, the mechanisms of taste bud maintenance have remained a major area of inquiry. In this article, we review the expression of regulatory genes in taste buds and their involvement in taste bud cell differentiation. Three major topics include: 1) the Sonic hedgehog (Shh)-expressing cell in the basal cell in taste buds as a transient precursor of elongated cells and as a signal center for the proliferation of progenitor cells; 2) the Mash1-expressing cell as an immature cell state of both Type II and Type III cells and as a mature cell state of Type III cell; and 3) the nerve dependency of gene expression in taste buds. Problems in the application of NCAM for the type III cell marker are also discussed.
Collapse
Affiliation(s)
- Hirohito Miura
- Department of Oral Physiology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan.
| | | | | |
Collapse
|
46
|
Ueda K, Ichimori Y, Okada H, Honma S, Wakisaka S. Immunolocalization of SNARE proteins in both type II and type III cells of rat taste buds. ACTA ACUST UNITED AC 2007; 69:289-96. [PMID: 17287583 DOI: 10.1679/aohc.69.289] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Double immunohistochemistry of soluble N-ethylmaleimide-sensitive fusion protein attachment protein receptor (SNARE) proteins [synaptosomal-associated protein of 25 kDa (SNAP-25), syntaxin and vesicle-associated protein-2 (VAMP-2)], and specific cell markers of taste buds cells [alpha-gustducin and phospholipase Cbeta2 (PLCbeta2) for type II cells; neural cell adhesion molecule (NCAM) for type III cells] was applied to gustatory epithelia of the rat circumvallate papillae. All three SNARE proteins were present in some elongated taste buds cells as well as intra-, peri- and subgemmal nerve fibers. Double immunohisotochemistry revealed that nearly all alpha-gustducin and PLCbeta2 immunoreactive cells expressed SNAP-25, syntaxin, and VAMP-2. A majority of NCAM immunoreactive cells showed immunoreactivity for these SNARE proteins. These results indicate that these synapse-associated proteins (SNAP-25, syntaxin and VAMP-2) are present in both type II cells and type III cells. Moreover, more than 50% of intragemmal cells containing SNARE proteins showed immunoreactivities for alpha-gustducin, PLCbeta2, and NCAM, suggesting the possible presence of transitional cells having histochemical properties of both type II and type III cells.
Collapse
Affiliation(s)
- Katsura Ueda
- Department of Oral Anatomy and Developmental Biology, Osaka University Graduate School of Dentistry, Japan
| | | | | | | | | |
Collapse
|
47
|
Seta Y, Kataoka S, Toyono T, Toyoshima K. Immunohistochemical localization of aromatic l-amino acid decarboxylase in mouse taste buds and developing taste papillae. Histochem Cell Biol 2007; 127:415-22. [PMID: 17211625 DOI: 10.1007/s00418-006-0257-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/27/2006] [Indexed: 12/27/2022]
Abstract
Aromatic L-amino acid decarboxylase (AADC) catalyses the decarboxylation of all aromatic L-amino acids. In mammals, AADC is expressed in many tissues besides the nervous system, and is associated with additional regulatory roles of dopamine and serotonin in a wide range of tissues. We examined the expression of AADC by using reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry. RT-PCR analysis showed that mRNA of AADC was detected in the taste bud-containing epithelium of the circumvallate papilla of mice. By immunohistochemical analyses, AADC was detected in a subset of taste bud cells of fungiform, foliate, and circumvallate papillae. Double-label studies showed that AADC colocalized with serotonin, NCAM, PLCbeta2, and PGP9.5. On the other hand, AADC never colocalized with alpha-gustducin. Our results of double staining with AADC and taste cell markers indicate that only the type III cells could convert 5-hydroxytryptophan (5-HTP) to serotonin within taste buds. Taken together with previous studies, the properties of the type III cell of taste buds exactly fit into the APUD (amine and amine precursor uptake and decarboxylation) cell scheme. Furthermore, in the developing circumvallate papilla, AADC are first detected in a small number of papillary epithelial cells at E14.5. By E18.5, AADC-positive epithelial cells also express PGP9.5, which is one of marker of taste cells, and these cells have been contacted by developing nerve fibers. These results suggest that AADC expression begins at early stages of taste bud cell differentiation, and biogenic amines may act on taste bud differentiation of tongue epithelial cells, and further may regulate innervation of taste bud progenitor cells.
Collapse
Affiliation(s)
- Yuji Seta
- Division of Oral Histology and Neurobiology, Department of Bioscience, Kyushu Dental College, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, 803-8580, Japan.
| | | | | | | |
Collapse
|
48
|
Qualitative and quantitative differences between taste buds of the rat and mouse. BMC Neurosci 2007; 8:5. [PMID: 17207280 PMCID: PMC1779794 DOI: 10.1186/1471-2202-8-5] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2006] [Accepted: 01/05/2007] [Indexed: 11/11/2022] Open
Abstract
Background Numerous electrophysiological, ultrastructural, and immunocytochemical studies on rodent taste buds have been carried out on rat taste buds. In recent years, however, the mouse has become the species of choice for molecular and other studies on sensory transduction in taste buds. Do rat and mouse taste buds have the same cell types, sensory transduction markers and synaptic proteins? In the present study we have used antisera directed against PLCβ2, α-gustducin, serotonin (5-HT), PGP 9.5 and synaptobrevin-2 to determine the percentages of taste cells expressing these markers in taste buds in both rodent species. We also determined the numbers of taste cells in the taste buds as well as taste bud volume. Results There are significant differences (p < 0.05) between mouse and rat taste buds in the percentages of taste cells displaying immunoreactivity for all five markers. Rat taste buds display significantly more immunoreactivity than mice for PLCβ2 (31.8% vs 19.6%), α-gustducin (18% vs 14.6%), and synaptobrevin-2 (31.2% vs 26.3%). Mice, however, have more cells that display immunoreactivity to 5-HT (15.9% vs 13.7%) and PGP 9.5 (14.3% vs 9.4%). Mouse taste buds contain an average of 85.8 taste cells vs 68.4 taste cells in rat taste buds. The average volume of a mouse taste bud (42,000 μm3) is smaller than a rat taste bud (64,200 μm3). The numerical density of taste cells in mouse circumvallate taste buds (2.1 cells/1000 μm3) is significantly higher than that in the rat (1.2 cells/1000 μm3). Conclusion These results suggest that rats and mice differ significantly in the percentages of taste cells expressing signaling molecules. We speculate that these observed dissimilarities may reflect differences in their gustatory processing.
Collapse
|
49
|
Yang R, Ma H, Thomas SM, Kinnamon JC. Immunocytochemical analysis of syntaxin-1 in rat circumvallate taste buds. J Comp Neurol 2007; 502:883-93. [PMID: 17447252 DOI: 10.1002/cne.21317] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Mammalian buds contain a variety of morphological taste cell types, but the type III taste cell is the only cell type that has synapses onto nerve processes. We hypothesize that taste cell synapses utilize the SNARE protein machinery syntaxin, SNAP-25, and synaptobrevin, as is used by synapses in the central nervous system (CNS) for Ca2+-dependent exocytosis. Previous studies have shown that taste cells with synapses display SNAP-25- and synaptobrevin-2-like immunoreactivity (LIR) (Yang et al. [2000a] J Comp Neurol 424:205-215, [2004] J Comp Neurol 471:59-71). In the present study we investigated the presynaptic membrane protein, syntaxin-1, in circumvallate taste buds of the rat. Our results indicate that diffuse cytoplasmic and punctate syntaxin-1-LIR are present in different subsets of taste cells. Diffuse, cytoplasmic syntaxin-1-LIR is present in type III cells while punctate syntaxin-1-LIR is present in type II cells. The punctate syntaxin-1-LIR is believed to be associated with Golgi bodies. All of the synapses associated with syntaxin-1-LIR taste cells are from type III cells onto nerve processes. These results support the proposition that taste cell synapses use classical SNARE machinery such as syntaxin-1 for neurotransmitter release in rat circumvallate taste buds.
Collapse
Affiliation(s)
- Ruibiao Yang
- Department of Biological Sciences, University of Denver, Denver, Colorado 80208, USA
| | | | | | | |
Collapse
|
50
|
Sekerková G, Freeman D, Mugnaini E, Bartles JR. Espin cytoskeletal proteins in the sensory cells of rodent taste buds. ACTA ACUST UNITED AC 2006; 34:171-82. [PMID: 16841162 PMCID: PMC2908427 DOI: 10.1007/s11068-005-8352-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2005] [Revised: 12/29/2005] [Accepted: 12/29/2005] [Indexed: 12/30/2022]
Abstract
Espins are multifunctional actin-bundling proteins that are highly enriched in the microvilli of certain chemosensory and mechanosensory cells, where they are believed to regulate the integrity and/or dimensions of the parallel-actin-bundle cytoskeletal scaffold. We have determined that, in rats and mice, affinity purified espin antibody intensely labels the lingual and palatal taste buds of the oral cavity and taste buds in the pharyngo-laryngeal region. Intense immunolabeling was observed in the apical, microvillar region of taste buds, while the level of cytoplasmic labeling in taste bud cells was considerably lower. Taste buds contain tightly packed collections of sensory cells (light, or type II plus type III) and supporting cells (dark, or type I), which can be distinguished by microscopic features and cell type-specific markers. On the basis of results obtained using an antigen-retrieval method in conjunction with double immunofluorescence for espin and sensory taste cell-specific markers, we propose that espins are expressed predominantly in the sensory cells of taste buds. In confocal images of rat circumvallate taste buds, we counted 21.5 +/- 0.3 espin-positive cells/taste bud, in agreement with a previous report showing 20.7 +/- 1.3 light cells/taste bud when counted at the ultrastructural level. The espin antibody labeled spindle-shaped cells with round nuclei and showed 100% colocalization with cell-specific markers recognizing all type II [inositol 1,4,5-trisphosphate receptor type III (IP(3)R(3))(,) alpha-gustducin, protein-specific gene product 9.5 (PGP9.5)] and a subpopulation of type III (IP(3)R(3), PGP9.5) taste cells. On average, 72%, 50%, and 32% of the espin-positive taste cells were labeled with antibodies to IP(3)R(3), alpha-gustducin, and PGP9.5, respectively. Upon sectional analysis, the taste buds of rat circumvallate papillae commonly revealed a multi-tiered, espin-positive apical cytoskeletal apparatus. One espin-positive zone, a collection of approximately 3 mum-long microvilli occupying the taste pore, was separated by an espin-depleted zone from a second espin-positive zone situated lower within the taste pit. This latter zone included espin-positive rod-like structures that occasionally extended basally to a depth of 10-12 mum into the cytoplasm of taste cells. We propose that the espin-positive zone in the taste pit coincides with actin bundles in association with the microvilli of type II taste cells, whereas the espin-positive microvilli in the taste pore are the single microvilli of type III taste cells.
Collapse
Affiliation(s)
- Gabriella Sekerková
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Chicago, IL 60611, USA
- Institute for Neuroscience, Northwestern University, Chicago, IL 60611, USA
| | - David Freeman
- Institute for Neuroscience, Northwestern University, Chicago, IL 60611, USA
| | - Enrico Mugnaini
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Chicago, IL 60611, USA
- Institute for Neuroscience, Northwestern University, Chicago, IL 60611, USA
| | - James R. Bartles
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Chicago, IL 60611, USA
- Institute for Neuroscience, Northwestern University, Chicago, IL 60611, USA
| |
Collapse
|