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Ishan M, Wang Z, Zhao P, Yao Y, Stice SL, Wells L, Mishina Y, Liu HX. Taste papilla cell differentiation requires the regulation of secretory protein production by ALK3-BMP signaling in the tongue mesenchyme. Development 2023; 150:dev201838. [PMID: 37680190 PMCID: PMC10560570 DOI: 10.1242/dev.201838] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Accepted: 09/01/2023] [Indexed: 09/09/2023]
Abstract
Taste papillae are specialized organs, each of which comprises an epithelial wall hosting taste buds and a core of mesenchymal tissue. In the present study, we report that during early taste papilla development in mouse embryos, bone morphogenetic protein (BMP) signaling mediated by type 1 receptor ALK3 in the tongue mesenchyme is required for epithelial Wnt/β-catenin activity and taste papilla differentiation. Mesenchyme-specific knockout (cKO) of Alk3 using Wnt1-Cre and Sox10-Cre resulted in an absence of taste papillae at E12.0. Biochemical and cell differentiation analyses demonstrated that mesenchymal ALK3-BMP signaling governed the production of previously unappreciated secretory proteins, i.e. it suppressed those that inhibit and facilitated those that promote taste papilla differentiation. Bulk RNA-sequencing analysis revealed many more differentially expressed genes (DEGs) in the tongue epithelium than in the mesenchyme in Alk3 cKO versus control. Moreover, we detected downregulated epithelial Wnt/β-catenin signaling and found that taste papilla development in the Alk3 cKO was rescued by the GSK3β inhibitor LiCl, but not by Wnt3a. Our findings demonstrate for the first time the requirement of tongue mesenchyme in taste papilla cell differentiation.
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Affiliation(s)
- Mohamed Ishan
- Regenerative Bioscience Center, Department of Animal and Dairy Science, College of Agricultural and Environmental Sciences, University of Georgia, Athens, GA 30602, USA
| | - Zhonghou Wang
- Regenerative Bioscience Center, Department of Animal and Dairy Science, College of Agricultural and Environmental Sciences, University of Georgia, Athens, GA 30602, USA
| | - Peng Zhao
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA
| | - Yao Yao
- Regenerative Bioscience Center, Department of Animal and Dairy Science, College of Agricultural and Environmental Sciences, University of Georgia, Athens, GA 30602, USA
| | - Steven L. Stice
- Regenerative Bioscience Center, Department of Animal and Dairy Science, College of Agricultural and Environmental Sciences, University of Georgia, Athens, GA 30602, USA
| | - Lance Wells
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA
| | - Yuji Mishina
- Department of Biologic and Materials Sciences, School of Dentistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - Hong-Xiang Liu
- Regenerative Bioscience Center, Department of Animal and Dairy Science, College of Agricultural and Environmental Sciences, University of Georgia, Athens, GA 30602, USA
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Ishan M, Wang Z, Zhao P, Yao Y, Stice S, Wells L, Mishina Y, Liu HX. Taste papilla cell differentiation requires tongue mesenchyme via ALK3-BMP signaling to regulate the production of secretory proteins. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.03.535414. [PMID: 37066397 PMCID: PMC10103976 DOI: 10.1101/2023.04.03.535414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Taste papillae are specialized organs each of which is comprised of an epithelial wall hosting taste buds and a core of mesenchymal tissue. In the present study, we report that during the early stages of embryonic development, bone morphogenetic protein (BMP) signaling mediated by type 1 receptor ALK3 in the tongue mesenchyme is required for the epithelial Wnt/β-catenin activity and taste papilla cell differentiation. Mesenchyme-specific knockout ( cKO ) of Alk3 using Wnt1-Cre and Sox10-Cre resulted in an absence of taste papillae at E12.0. Biochemical and cell differentiation analyses demonstrated that mesenchymal ALK3-BMP signaling governs the production of previously unappreciated secretory proteins, i.e., suppresses those that inhibiting and facilitates those promoting taste cell differentiation. Bulk RNA-Sequencing analysis revealed many more differentially expressed genes (DEGs) in the tongue epithelium than in the mesenchyme in Alk3 cKO vs control. Moreover, we detected a down-regulated epithelial Wnt/β-catenin signaling, and taste papilla development in the Alk3 cKO was rescued by GSK3β inhibitor LiCl, but not Wnt3a. Our findings demonstrate for the first time the requirement of tongue mesenchyme in taste papilla cell differentiation. Summary statement This is the first set of data to implicate the requirement of tongue mesenchyme in taste papilla cell differentiation.
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Vercauteren Drubbel A, Beck B. Single-cell transcriptomics uncovers the differentiation of a subset of murine esophageal progenitors into taste buds in vivo. SCIENCE ADVANCES 2023; 9:eadd9135. [PMID: 36888721 PMCID: PMC9995038 DOI: 10.1126/sciadv.add9135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 01/24/2023] [Indexed: 06/18/2023]
Abstract
Mouse esophagus is lined with a stratified epithelium, which is maintained by the constant renewal of unipotent progenitors. In this study, we profiled mouse esophagus by single-cell RNA sequencing and found taste buds specifically in the cervical segment of the esophagus. These taste buds have the same cellular composition as the ones from the tongue but express fewer taste receptor types. State-of-the-art transcriptional regulatory network analysis allowed the identification of specific transcription factors associated to the differentiation of immature progenitors into the three different taste bud cell types. Lineage tracing experiments revealed that esophageal taste buds arise from squamous bipotent progenitor, thus demonstrating that all esophageal progenitors are not unipotent. Our cell resolution characterization of cervical esophagus epithelium will enable a better understanding of esophageal progenitor potency and insights into the mechanisms involved in the development of taste buds.
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Affiliation(s)
| | - Benjamin Beck
- IRIBHM, ULB/ Faculty of medicine, 808 Route de Lennik, 1070 Brussels, Belgium
- Welbio/FNRS Principal investigator at IRIBHM, 808 Route de Lennik, 1070 Brussels, Belgium
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Kumari A, Mistretta CM. Anterior and Posterior Tongue Regions and Taste Papillae: Distinct Roles and Regulatory Mechanisms with an Emphasis on Hedgehog Signaling and Antagonism. Int J Mol Sci 2023; 24:4833. [PMID: 36902260 PMCID: PMC10002505 DOI: 10.3390/ijms24054833] [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: 02/01/2023] [Revised: 02/21/2023] [Accepted: 02/25/2023] [Indexed: 03/06/2023] Open
Abstract
Sensory receptors across the entire tongue are engaged during eating. However, the tongue has distinctive regions with taste (fungiform and circumvallate) and non-taste (filiform) organs that are composed of specialized epithelia, connective tissues, and innervation. The tissue regions and papillae are adapted in form and function for taste and somatosensation associated with eating. It follows that homeostasis and regeneration of distinctive papillae and taste buds with particular functional roles require tailored molecular pathways. Nonetheless, in the chemosensory field, generalizations are often made between mechanisms that regulate anterior tongue fungiform and posterior circumvallate taste papillae, without a clear distinction that highlights the singular taste cell types and receptors in the papillae. We compare and contrast signaling regulation in the tongue and emphasize the Hedgehog pathway and antagonists as prime examples of signaling differences in anterior and posterior taste and non-taste papillae. Only with more attention to the roles and regulatory signals for different taste cells in distinct tongue regions can optimal treatments for taste dysfunctions be designed. In summary, if tissues are studied from one tongue region only, with associated specialized gustatory and non-gustatory organs, an incomplete and potentially misleading picture will emerge of how lingual sensory systems are involved in eating and altered in disease.
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Affiliation(s)
- Archana Kumari
- Cell Biology and Neuroscience, Rowan University School of Osteopathic Medicine, Stratford, NJ 08084, USA
| | - Charlotte M. Mistretta
- Department of Biologic and Materials Sciences & Prosthodontics, School of Dentistry, University of Michigan, Ann Arbor, MI 48109, USA
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Rhee YH, Choi YH, Hu AC, Lee MY, Ahn JC, Kim S, Mo JH, Woo SH, Chung PS. Role of Transient Receptor Potential Vanilloid 1 in Sonic Hedgehog-Dependent Taste Bud Differentiation. LIFE (BASEL, SWITZERLAND) 2022; 13:life13010075. [PMID: 36676024 PMCID: PMC9862146 DOI: 10.3390/life13010075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 12/19/2022] [Accepted: 12/23/2022] [Indexed: 12/29/2022]
Abstract
Taste bud cell differentiation is extremely important for taste sensation. Immature taste bud cells cannot function during taste perception transmission to the nerve. In this study, we investigated whether hedgehog signaling affected taste bud cell differentiation and whether transient receptor potential vanilloid 1 (TRPV1) played a key role in dry mouth. The induction of dry mouth due to salivary gland resection (SGR) was confirmed on the basis of reduced salivation and disrupted fungiform papillae. The expression of keratin 8 (K8) of taste bud cells, neurofilament (NF), sonic hedgehog (Shh), and glioma-associated oncogene homolog 1 (Gli1) around taste bud cells was downregulated; however, the expression of TRPV1, P2X purinoceptor 3 (P2X3), and hematopoietic stem cell factor (c-Kit) was upregulated at the NF ends in the dry mouth group. To investigate the effect of TRPV1 defect on dry mouth, we induced dry mouth in the TRPV-/- group. The K8, NF, and P2X3 expression patterns were the same in the TRPV1 wild-type and TRPV1-/- dry mouth groups. However, Shh and c-Kit expression decreased regardless of dry mouth in the case of TRPV1 deficiency. These results indicated that TRPV1 positively regulated proliferation during taste bud cell injury by blocking the Shh/Gli1 pathway. In addition, not only cell proliferation but also differentiation of taste bud cells could not be regulated under TRPV1-deficiency conditions. Thus, TRPV1 positively regulates taste bud cell innervation and differentiation; this finding could be valuable in the clinical treatment of dry mouth-related taste dysfunction.
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Affiliation(s)
- Yun-Hee Rhee
- Beckman Laser Institute Korea, Dankook University, 119 Dandae-ro, Cheonan 31116, Republic of Korea
- Medical Laser Research Center, Dankook University, 119 Dandae-ro, Cheonan 31116, Republic of Korea
- Laser Translational Clinical Trial Center, Dankook University Hospital, Cheonan 31116, Republic of Korea
| | - Young-Hoon Choi
- Laser Translational Clinical Trial Center, Dankook University Hospital, Cheonan 31116, Republic of Korea
| | - Allison C. Hu
- Beckman Laser Institute and Medical Clinic, University of California Irvine, 1002 Health Sciences Rd., Irvine, CA 92697, USA
| | - Min Young Lee
- Beckman Laser Institute Korea, Dankook University, 119 Dandae-ro, Cheonan 31116, Republic of Korea
- Medical Laser Research Center, Dankook University, 119 Dandae-ro, Cheonan 31116, Republic of Korea
- Department of Otolaryngology-Head and Neck Surgery, College of Medicine, Dankook University, Cheonan 31116, Republic of Korea
| | - Jin-Chul Ahn
- Beckman Laser Institute Korea, Dankook University, 119 Dandae-ro, Cheonan 31116, Republic of Korea
- Medical Laser Research Center, Dankook University, 119 Dandae-ro, Cheonan 31116, Republic of Korea
| | - Sehwan Kim
- Beckman Laser Institute Korea, Dankook University, 119 Dandae-ro, Cheonan 31116, Republic of Korea
| | - Ji-Hun Mo
- Beckman Laser Institute Korea, Dankook University, 119 Dandae-ro, Cheonan 31116, Republic of Korea
- Medical Laser Research Center, Dankook University, 119 Dandae-ro, Cheonan 31116, Republic of Korea
- Laser Translational Clinical Trial Center, Dankook University Hospital, Cheonan 31116, Republic of Korea
- Department of Otolaryngology-Head and Neck Surgery, College of Medicine, Dankook University, Cheonan 31116, Republic of Korea
| | - Seung Hoon Woo
- Beckman Laser Institute Korea, Dankook University, 119 Dandae-ro, Cheonan 31116, Republic of Korea
- Medical Laser Research Center, Dankook University, 119 Dandae-ro, Cheonan 31116, Republic of Korea
- Laser Translational Clinical Trial Center, Dankook University Hospital, Cheonan 31116, Republic of Korea
- Department of Otolaryngology-Head and Neck Surgery, College of Medicine, Dankook University, Cheonan 31116, Republic of Korea
| | - Phil-Sang Chung
- Beckman Laser Institute Korea, Dankook University, 119 Dandae-ro, Cheonan 31116, Republic of Korea
- Medical Laser Research Center, Dankook University, 119 Dandae-ro, Cheonan 31116, Republic of Korea
- Laser Translational Clinical Trial Center, Dankook University Hospital, Cheonan 31116, Republic of Korea
- Department of Otolaryngology-Head and Neck Surgery, College of Medicine, Dankook University, Cheonan 31116, Republic of Korea
- Correspondence:
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Type II/III cell composition and NCAM expression in taste buds. Cell Tissue Res 2021; 385:557-570. [PMID: 33942154 DOI: 10.1007/s00441-021-03452-5] [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: 12/22/2020] [Accepted: 03/15/2021] [Indexed: 10/21/2022]
Abstract
Taste buds are localized in fungiform (FF), foliate (FL), and circumvallate (CV) papillae on the tongue, and taste buds also occur on the soft palate (SP). Mature elongate cells within taste buds are constantly renewed from stem cells and classified into three cell types, Types I, II, and III. These cell types are generally assumed to reside in respective taste buds in a particular ratio corresponding to taste regions. A variety of cell-type markers were used to analyze taste bud cells. NCAM is the first established marker for Type III cells and is still often used. However, NCAM was examined mainly in the CV, but not sufficiently in other regions. Furthermore, our previous data suggested that NCAM may be transiently expressed in the immature stage of Type II cells. To precisely assess NCAM expression as a Type III cell marker, we first examined Type II and III cell-type markers, IP3R3 and CA4, respectively, and then compared NCAM with them using whole-mount immunohistochemistry. IP3R3 and CA4 were segregated from each other, supporting the reliability of these markers. The ratio between Type II and III cells varied widely among taste buds in the respective regions (Pearson's r = 0.442 [CV], 0.279 [SP], and - 0.011 [FF]), indicating that Type II and III cells are contained rather independently in respective taste buds. NCAM immunohistochemistry showed that a subset of taste bud cells were NCAM(+)CA4(-). While NCAM(+)CA4(-) cells were IP3R3(-) in the CV, the majority of them were IP3R3(+) in the SP and FF.
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Gaillard D, Barlow LA. A Mechanistic Overview of Taste Bud Maintenance and Impairment in Cancer Therapies. Chem Senses 2021; 46:6161548. [PMID: 33693542 DOI: 10.1093/chemse/bjab011] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Since the early 20th century, progress in cancer therapies has significantly improved disease prognosis. Nonetheless, cancer treatments are often associated with side effects that can negatively affect patient well-being and disrupt the course of treatment. Among the main side effects, taste impairment is associated with depression, malnutrition, and morbid weight loss. Although relatively common, taste disruption associated with cancer therapies remains poorly understood. Here, we review the current knowledge related to the molecular mechanisms underlying taste maintenance and disruption in the context of cancer therapies.
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Affiliation(s)
- Dany Gaillard
- Department of Cell & Developmental Biology, and the Rocky Mountain Taste & Smell Center, University of Colorado Anschutz Medical Campus, 12801 East 17th Avenue, Mail Stop 8108, Aurora, CO 80045, USA
| | - Linda A Barlow
- Department of Cell & Developmental Biology, and the Rocky Mountain Taste & Smell Center, University of Colorado Anschutz Medical Campus, 12801 East 17th Avenue, Mail Stop 8108, Aurora, CO 80045, USA
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Gaillard D, Shechtman LA, Millar SE, Barlow LA. Fractionated head and neck irradiation impacts taste progenitors, differentiated taste cells, and Wnt/β-catenin signaling in adult mice. Sci Rep 2019; 9:17934. [PMID: 31784592 PMCID: PMC6884601 DOI: 10.1038/s41598-019-54216-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 11/10/2019] [Indexed: 12/13/2022] Open
Abstract
Head and neck cancer patients receiving conventional repeated, low dose radiotherapy (fractionated IR) suffer from taste dysfunction that can persist for months and often years after treatment. To understand the mechanisms underlying functional taste loss, we established a fractionated IR mouse model to characterize how taste buds are affected. Following fractionated IR, we found as in our previous study using single dose IR, taste progenitor proliferation was reduced and progenitor cell number declined, leading to interruption in the supply of new taste receptor cells to taste buds. However, in contrast to a single dose of IR, we did not encounter increased progenitor cell death in response to fractionated IR. Instead, fractionated IR induced death of cells within taste buds. Overall, taste buds were smaller and fewer following fractionated IR, and contained fewer differentiated cells. In response to fractionated IR, expression of Wnt pathway genes, Ctnnb1, Tcf7, Lef1 and Lgr5 were reduced concomitantly with reduced progenitor proliferation. However, recovery of Wnt signaling post-IR lagged behind proliferative recovery. Overall, our data suggest carefully timed, local activation of Wnt/β-catenin signaling may mitigate radiation injury and/or speed recovery of taste cell renewal following fractionated IR.
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Affiliation(s)
- Dany Gaillard
- Department of Cell & Developmental Biology, University of Colorado Anschutz Medical Campus, Mail Stop 8108, 12801 East 17th Avenue, Aurora, CO, 80045, USA.
- Rocky Mountain Taste & Smell Center, University of Colorado Anschutz Medical Campus, Mail Stop 8108, 12801 East 17th Avenue, Aurora, CO, 80045, USA.
| | - Lauren A Shechtman
- Department of Cell & Developmental Biology, University of Colorado Anschutz Medical Campus, Mail Stop 8108, 12801 East 17th Avenue, Aurora, CO, 80045, USA
- Rocky Mountain Taste & Smell Center, University of Colorado Anschutz Medical Campus, Mail Stop 8108, 12801 East 17th Avenue, Aurora, CO, 80045, USA
| | - Sarah E Millar
- Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Department of Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Department of Dermatology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Linda A Barlow
- Department of Cell & Developmental Biology, University of Colorado Anschutz Medical Campus, Mail Stop 8108, 12801 East 17th Avenue, Aurora, CO, 80045, USA.
- Rocky Mountain Taste & Smell Center, University of Colorado Anschutz Medical Campus, Mail Stop 8108, 12801 East 17th Avenue, Aurora, CO, 80045, USA.
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Taste loss with obesity in mice and men. Int J Obes (Lond) 2019; 44:739-743. [PMID: 31388094 DOI: 10.1038/s41366-019-0429-6] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 05/24/2019] [Accepted: 06/30/2019] [Indexed: 01/11/2023]
Abstract
BACKGROUND Our sense of taste is critical in defining our food choices and habits. Located primarily in our tongue, taste buds are small assemblies of constantly renewing sensory cells, tasked with evaluating oral stimuli before the food we eat is consumed. METHODS Using both mice and a free-living human population, we tracked taste papilla abundancy with weight gain, to test for deficiencies in the taste system of obese mice and humans with increased adiposity. RESULTS Mice fed a high-fat diet for 8 weeks expressed markers for all subtypes of taste cells at a lower level than chow-fed counterparts. This came alongside the loss of markers for taste cell proliferation (Ki-67) and development (β-catenin), as well as lower fungiform papillae density, consistent with earlier results showing lower circumvallate taste bud abundance in obese mice. Likewise, in a population of college students tracked through 4 years of college attendance, the change in density of fungiform papillae, which house taste buds in the anterior tongue, was negatively correlated with change in neck circumference, a marker of adiposity. CONCLUSIONS These results highlight changes in taste during weight gain as a potentially important consideration in the study of obesity.
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Takahashi Y, Takahashi H, Stern PL, Kirita T, Tsuboi A. Expression of Oncofetal Antigen 5T4 in Murine Taste Papillae. Front Cell Neurosci 2019; 13:343. [PMID: 31417363 PMCID: PMC6685444 DOI: 10.3389/fncel.2019.00343] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 07/12/2019] [Indexed: 12/26/2022] Open
Abstract
Background: Multicellular taste buds located within taste papillae on the tongue mediate taste sensation. In taste papillae, taste bud cells (TBCs), such as taste receptor cells and taste precursor cells, and the surrounding lingual epithelium including epithelial progenitors (also called taste stem/progenitor cells) are maintained by continuous cell turnover throughout life. However, it remains unknown how the cells constituting taste buds proliferate and differentiate to maintain taste bud tissue. Based on in situ hybridization (ISH) screening, we demonstrated that the oncofetal antigen 5T4 (also known as trophoblast glycoprotein: TPBG) gene is expressed in the adult mouse tongue. Results: In immunohistochemistry of coronal tongue sections, 5T4 protein was detected at a low level exclusively in the basal part of the lingual epithelium in developing and adult mice, and at a high level particularly in foliate papillae and circumvallate papillae (CVPs). Furthermore, immunohistochemistry of the basal part of CVPs indicated that the proliferation marker PCNA (proliferating cell nuclear antigen) co-localized with 5T4. 5T4 was strongly expressed in Krt5+ epithelial progenitors and Shh+ taste precursor cells, but weakly in mature taste receptor cells. The number of proliferating cells in the CVP was higher in 5T4-knockout mice than in wild-type (WT) mice, while neither cell differentiation nor the size of taste buds differed between these two groups of mice. Notably, X-ray irradiation enhanced cell proliferation more in 5T4-knockout mice than in WT mice. Conclusion: Our results suggest that 5T4, expressed in epithelial progenitors (taste stem/progenitor cells), and taste precursor cells, may influence the maintenance of taste papillae under both normal and injury conditions.
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Affiliation(s)
- Yuka Takahashi
- Department of Oral and Maxillofacial Surgery, Nara Medical University, Kashihara, Japan
| | - Hiroo Takahashi
- Department of Oral and Maxillofacial Surgery, Nara Medical University, Kashihara, Japan
- Department of Molecular Neurobiology, Faculty of Medicine, Kagawa University, Miki-cho, Japan
| | - Peter L. Stern
- Division of Molecular and Clinical Cancer Sciences, University of Manchester, Manchester, United Kingdom
| | - Tadaaki Kirita
- Department of Oral and Maxillofacial Surgery, Nara Medical University, Kashihara, Japan
| | - Akio Tsuboi
- Department of Oral and Maxillofacial Surgery, Nara Medical University, Kashihara, Japan
- Laboratory for Cellular and Molecular Neurobiology, Graduate School of Frontier Biosciences, Osaka University, Suita, Japan
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Delay ER, Socia SH, Girardin JL, Jewkes BC, King JH, Delay RJ. Cyclophosphamide and the taste system: Effects of dose fractionation and amifostine on taste cell renewal. PLoS One 2019; 14:e0214890. [PMID: 30947285 PMCID: PMC6448888 DOI: 10.1371/journal.pone.0214890] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 03/22/2019] [Indexed: 01/08/2023] Open
Abstract
Chemotherapy often causes side effects that include disturbances in taste functions. Cyclophosphamide (CYP) is a chemotherapy drug that, after a single dose, elevates murine taste thresholds at times related to drug-induced losses of taste sensory cells and disruptions of proliferating cells that renew taste sensory cells. Pretreatment with amifostine can protect the taste system from many of these effects. This study compared the effects of a single dose (75 mg/kg) of CYP with effects generated by fractionated dosing of CYP (5 doses of 15 mg/kg), a dosing approach often used during chemotherapy, on the taste system of mice using immunohistochemistry. Dose fractionation prolonged the suppressive effects of CYP on cell proliferation responsible for renewal of taste sensory cells. Fractionation also reduced the total number of cells and the proportion of Type II cells within taste buds. The post-injection time of these losses coincided with the life span of Type I and II taste cells combined with lack of replacement cells. Fractionated dosing also decreased Type III cells more than a single dose, but loss of these cells may be due to factors related to the general health and/or cell renewal of taste buds rather than the life span of Type III cells. In general, pretreatment with amifostine appeared to protect taste cell renewal and the population of cells within taste buds from the cytotoxic effects of CYP with few observable adverse effects due to repeated administration. These findings may have important implications for patients undergoing chemotherapy.
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Affiliation(s)
- Eugene R. Delay
- Department of Biology and Neuroscience Program, University of Vermont, Burlington, Vermont, United States of America
- * E-mail:
| | - Sarah H. Socia
- Department of Biology and Neuroscience Program, University of Vermont, Burlington, Vermont, United States of America
| | - Jessica L. Girardin
- Department of Biology and Neuroscience Program, University of Vermont, Burlington, Vermont, United States of America
| | - Benjamin C. Jewkes
- Department of Biology and Neuroscience Program, University of Vermont, Burlington, Vermont, United States of America
| | - John H. King
- Department of Biology and Neuroscience Program, University of Vermont, Burlington, Vermont, United States of America
| | - Rona J. Delay
- Department of Biology and Neuroscience Program, University of Vermont, Burlington, Vermont, United States of America
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Zheng X, Xu X, He JZ, Zhang P, Chen J, Zhou XD. [Development and homeostasis of taste buds in mammals]. HUA XI KOU QIANG YI XUE ZA ZHI = HUAXI KOUQIANG YIXUE ZAZHI = WEST CHINA JOURNAL OF STOMATOLOGY 2018; 36:552-558. [PMID: 30465351 DOI: 10.7518/hxkq.2018.05.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Taste is mediated by multicellular taste buds distributed throughout the oral and pharyngeal cavities. The taste buds can detect five basic tastes: sour, sweet, bitter, salty and umami, allowing mammals to select nutritious foods and avoid the ingestion of toxic and rotten foods. Once developed, the taste buds undergo continuous renewal throughout the adult life. In the past decade, significant progress has been achived in delineating the cellular and molecular mechanisms governing taste buds development and homeostasis. With this knowledges and in-depth investigations in the future, we can achieve the precise management of taste dysfunctions such as dysgeusia and ageusia.
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Affiliation(s)
- Xin Zheng
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & Dept. of Conservative Dentistry and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Xin Xu
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & Dept. of Conservative Dentistry and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Jin-Zhi He
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & Dept. of Conservative Dentistry and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Ping Zhang
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & Dept. of Conservative Dentistry and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Jiao Chen
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & Dept. of Conservative Dentistry and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Xue-Dong Zhou
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & Dept. of Conservative Dentistry and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
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Li F, Niu B, Zhu M. Ablation of NTPDase2+ cells inhibits the formation of filiform papillae in tongue tip. Animal Model Exp Med 2018; 1:143-151. [PMID: 30891559 PMCID: PMC6388074 DOI: 10.1002/ame2.12021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 05/31/2018] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Lingual epithelia in the tongue tip are among the most rapidly regenerating tissues, but the mechanism of cell genesis in this tissue is still unknown. Previous study has suggested the existence of multiple stem cell pools in lingual epithelia and papillae. Like K14+ and Sox2+ cells, NTPDase2+ cells have characteristics of stem cells. METHODS We employed a system using doxycycline to conditionally ablate NTPDase2+ cells in lingual epithelia and papillae by regulated expression of the diphtheria toxin A (DTA) gene. Transgenic lines, which expressed the rtTA gene in NTPDase2+ cells, were produced by pronuclear injection of zygotes from C57BL/6 mice using the BAC clone RP23-47P18. The NTPDase2-rtTA transgenic mice were crossed with the TetO-DTA transgenic animals. The double transgenic mice were treated with doxycycline. Doxycycline (Dox) was diluted in 5% sucrose in water to a final concentration of 0.3-0.5 mg/mL and supplied as drinking water. RESULTS After 15 days of Dox induction, the expression of NTPDase2, Sox2 and K14 was ablated from lingual epithelia. DTA expression in NTPDase2+ cells did not inhibit the turnover of GNAT3+ or PLCβ2+ cells in taste buds, nor the expression of S100β beneath lingual epithelia and papillae. After 35 days ablation of NTPDase2+ cells, the basic structure of lingual epithelia and papillae remained intact. However, the ratio of cell to total tissue area was decreased in lingual epithelia and circumvallate (CV) papillae. DTA expression also inhibited the regeneration of filiform papillae on the dorsal surface of the tongue tip. CONCLUSIONS These studies provide important insights into the understanding of dynamic equilibrium among the multiple stem cell populations present in the lingual epithelia and papillae.
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Affiliation(s)
- Feng Li
- Department of Laboratory Animal ScienceShanghai Public Health Clinical CenterFudan UniversityShanghaiChina
| | - Bo‐Wen Niu
- Department of Laboratory Animal ScienceShanghai Public Health Clinical CenterFudan UniversityShanghaiChina
| | - Meng‐Min Zhu
- Department of Laboratory Animal ScienceShanghai Public Health Clinical CenterFudan UniversityShanghaiChina
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14
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Liu HX, Rajapaksha P, Wang Z, Kramer NE, Marshall BJ. An Update on the Sense of Taste in Chickens: A Better Developed System than Previously Appreciated. ACTA ACUST UNITED AC 2018; 8. [PMID: 29770259 PMCID: PMC5951165 DOI: 10.4172/2155-9600.1000686] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Taste is important in guiding nutritive choices and motivating food intake. The sensory organs for taste are the taste buds, that transduce gustatory stimuli into neural signals. It has been reported that chickens have a low taste bud number and thus low taste acuity. However, more recent studies indicate that chickens have a well-developed taste system and the reported number and distribution of taste buds may have been significantly underestimated. Chickens, as a well-established animal model for research, are also the major species of animals in the poultry industry. Thus, a clear understanding of taste organ formation and the effects of taste sensation on nutrition and feeding practices is important for improving livestock production strategies. In this review, we provide an update on recent findings in chicken taste buds and taste sensation indicating that the chicken taste organ is better developed than previously thought and can serve as an ideal system for multidisciplinary studies including organogenesis, regenerative medicine, feeding and nutritional choices.
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Affiliation(s)
- Hong-Xiang Liu
- Bioscience Center, Department of Animal and Dairy Science, College of Agricultural and Environmental Sciences, University of Georgia, USA
| | - Prasangi Rajapaksha
- Bioscience Center, Department of Animal and Dairy Science, College of Agricultural and Environmental Sciences, University of Georgia, USA
| | - Zhonghou Wang
- Bioscience Center, Department of Animal and Dairy Science, College of Agricultural and Environmental Sciences, University of Georgia, USA
| | - Naomi E Kramer
- Bioscience Center, Department of Animal and Dairy Science, College of Agricultural and Environmental Sciences, University of Georgia, USA
| | - Brett J Marshall
- Bioscience Center, Department of Animal and Dairy Science, College of Agricultural and Environmental Sciences, University of Georgia, USA
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15
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Mukherjee N, Pal Choudhuri S, Delay RJ, Delay ER. Cellular mechanisms of cyclophosphamide-induced taste loss in mice. PLoS One 2017; 12:e0185473. [PMID: 28950008 PMCID: PMC5614555 DOI: 10.1371/journal.pone.0185473] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2017] [Accepted: 09/13/2017] [Indexed: 11/18/2022] Open
Abstract
Many commonly prescribed chemotherapy drugs such as cyclophosphamide (CYP) have adverse side effects including disruptions in taste which can result in loss of appetite, malnutrition, poorer recovery and reduced quality of life. Previous studies in mice found evidence that CYP has a two-phase disturbance in taste behavior: a disturbance immediately following drug administration and a second which emerges several days later. In this study, we examined the processes by which CYP disturbs the taste system by examining the effects of the drug on taste buds and cells responsible for taste cell renewal using immunohistochemical assays. Data reported here suggest CYP has direct cytotoxic effects on lingual epithelium immediately following administration, causing an early loss of taste sensory cells. Types II and III cells in fungiform taste buds appear to be more susceptible to this effect than circumvallate cells. In addition, CYP disrupts the population of rapidly dividing cells in the basal layer of taste epithelium responsible for taste cell renewal, manifesting a disturbance days later. The loss of these cells temporarily retards the system’s capacity to replace Type II and Type III taste sensory cells that survived the cytotoxic effects of CYP and died at the end of their natural lifespan. The timing of an immediate, direct loss of taste cells and a delayed, indirect loss without replacement of taste sensory cells are broadly congruent with previously published behavioral data reporting two periods of elevated detection thresholds for umami and sucrose stimuli. These findings suggest that chemotherapeutic disturbances in the peripheral mechanisms of the taste system may cause dietary challenges at a time when the cancer patient has significant need for well balanced, high energy nutritional intake.
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Affiliation(s)
- Nabanita Mukherjee
- Department of Biology and Vermont Chemosensory Group, University of Vermont, Burlington, Vermont, United States of America
| | - Shreoshi Pal Choudhuri
- Department of Biology and Vermont Chemosensory Group, University of Vermont, Burlington, Vermont, United States of America
| | - Rona J. Delay
- Department of Biology and Vermont Chemosensory Group, University of Vermont, Burlington, Vermont, United States of America
| | - Eugene R. Delay
- Department of Biology and Vermont Chemosensory Group, University of Vermont, Burlington, Vermont, United States of America
- * E-mail:
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16
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Gaillard D, Bowles SG, Salcedo E, Xu M, Millar SE, Barlow LA. β-catenin is required for taste bud cell renewal and behavioral taste perception in adult mice. PLoS Genet 2017; 13:e1006990. [PMID: 28846687 PMCID: PMC5591015 DOI: 10.1371/journal.pgen.1006990] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 09/08/2017] [Accepted: 08/21/2017] [Indexed: 02/07/2023] Open
Abstract
Taste stimuli are transduced by taste buds and transmitted to the brain via afferent gustatory fibers. Renewal of taste receptor cells from actively dividing progenitors is finely tuned to maintain taste sensitivity throughout life. We show that conditional β-catenin deletion in mouse taste progenitors leads to rapid depletion of progenitors and Shh+ precursors, which in turn causes taste bud loss, followed by loss of gustatory nerve fibers. In addition, our data suggest LEF1, TCF7 and Wnt3 are involved in a Wnt pathway regulatory feedback loop that controls taste cell renewal in the circumvallate papilla epithelium. Unexpectedly, taste bud decline is greater in the anterior tongue and palate than in the posterior tongue. Mutant mice with this regional pattern of taste bud loss were unable to discern sweet at any concentration, but could distinguish bitter stimuli, albeit with reduced sensitivity. Our findings are consistent with published reports wherein anterior taste buds have higher sweet sensitivity while posterior taste buds are better tuned to bitter, and suggest β-catenin plays a greater role in renewal of anterior versus posterior taste buds. By remaining relatively constant throughout adult life, the sense of taste helps keep the body healthy. However, taste perception can be disrupted by various environmental factors, including cancer therapies. Here, we show that Wnt/β-catenin signaling, a pathway known to control normal tissue maintenance and associated with the development of cancers, is required for taste cell renewal and behavioral taste sensitivity in mice. Our findings are significant as they suggest that chemotherapies targeting the Wnt pathway in cancerous tissues may cause taste dysfunction and further diminish the quality of life of patients.
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Affiliation(s)
- Dany Gaillard
- Department of Cell & Developmental Biology and the Rocky Mountain Taste & Smell Center, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - Spencer G. Bowles
- Department of Cell & Developmental Biology and the Rocky Mountain Taste & Smell Center, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - Ernesto Salcedo
- Department of Cell & Developmental Biology and the Rocky Mountain Taste & Smell Center, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - Mingang Xu
- Departments of Dermatology and Cell & Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Sarah E. Millar
- Departments of Dermatology and Cell & Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Linda A. Barlow
- Department of Cell & Developmental Biology and the Rocky Mountain Taste & Smell Center, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
- * E-mail:
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17
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RNA-Seq analysis on chicken taste sensory organs: An ideal system to study organogenesis. Sci Rep 2017; 7:9131. [PMID: 28831098 PMCID: PMC5567234 DOI: 10.1038/s41598-017-09299-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 07/25/2017] [Indexed: 12/21/2022] Open
Abstract
RNA-Seq is a powerful tool in transcriptomic profiling of cells and tissues. We recently identified many more taste buds than previously appreciated in chickens using molecular markers to stain oral epithelial sheets of the palate, base of oral cavity, and posterior tongue. In this study, RNA-Seq was performed to understand the transcriptomic architecture of chicken gustatory tissues. Interestingly, taste sensation related genes and many more differentially expressed genes (DEGs) were found between the epithelium and mesenchyme in the base of oral cavity as compared to the palate and posterior tongue. Further RNA-Seq using specifically defined tissues of the base of oral cavity demonstrated that DEGs between gustatory (GE) and non-gustatory epithelium (NGE), and between GE and the underlying mesenchyme (GM) were enriched in multiple GO terms and KEGG pathways, including many biological processes. Well-known genes for taste sensation were highly expressed in the GE. Moreover, genes of signaling components important in organogenesis (Wnt, TGFβ/ BMP, FGF, Notch, SHH, Erbb) were differentially expressed between GE and GM. Combined with other features of chicken taste buds, e.g., uniquely patterned array and short turnover cycle, our data suggest that chicken gustatory tissue provides an ideal system for multidisciplinary studies, including organogenesis and regenerative medicine.
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18
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Abstract
Taste cells undergo constant turnover throughout life; however, the molecular mechanisms governing taste cell generation are not well understood. Using RNA-Seq, we systematically surveyed the transcriptome landscape of taste organoids at different stages of growth. Our data show the staged expression of a variety of genes and identify multiple signaling pathways underlying taste cell differentiation and taste stem/progenitor cell proliferation. For example, transcripts of taste receptors appear only or predominantly in late-stage organoids. Prior to that, transcription factors and other signaling elements are upregulated. RNA-Seq identified a number of well-characterized signaling pathways in taste organoid cultures, such as those involving Wnt, bone morphogenetic proteins (BMPs), Notch, and Hedgehog (Hh). By pharmacological manipulation, we demonstrate that Wnt, BMPs, Notch, and Hh signaling pathways are necessary for taste cell proliferation, differentiation and cell fate determination. The temporal expression profiles displayed by taste organoids may also lead to the identification of currently unknown transducer elements underlying sour, salt, and other taste qualities, given the staged expression of taste receptor genes and taste transduction elements in cultured organoids.
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19
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WNT10A mutation causes ectodermal dysplasia by impairing progenitor cell proliferation and KLF4-mediated differentiation. Nat Commun 2017; 8:15397. [PMID: 28589954 PMCID: PMC5467248 DOI: 10.1038/ncomms15397] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2016] [Accepted: 03/27/2017] [Indexed: 02/06/2023] Open
Abstract
Human WNT10A mutations are associated with developmental tooth abnormalities and adolescent onset of a broad range of ectodermal defects. Here we show that β-catenin pathway activity and adult epithelial progenitor proliferation are reduced in the absence of WNT10A, and identify Wnt-active self-renewing stem cells in affected tissues including hair follicles, sebaceous glands, taste buds, nails and sweat ducts. Human and mouse WNT10A mutant palmoplantar and tongue epithelia also display specific differentiation defects that are mimicked by loss of the transcription factor KLF4. We find that β-catenin interacts directly with region-specific LEF/TCF factors, and with KLF4 in differentiating, but not proliferating, cells to promote expression of specialized keratins required for normal tissue structure and integrity. Our data identify WNT10A as a critical ligand controlling adult epithelial proliferation and region-specific differentiation, and suggest downstream β-catenin pathway activation as a potential approach to ameliorate regenerative defects in WNT10A patients. Human WNT10A mutations are associated with dental defects and adult onset ectodermal dysplasia. Xu et al. show that WNT10A-activated ß-catenin plays dual roles in adult epithelial progenitor proliferation and differentiation by complexing with KLF4 in differentiating, but not proliferating, cells.
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20
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Abstract
The tongue is an elaborate complex of heterogeneous tissues with taste organs of diverse embryonic origins. The lingual taste organs are papillae, composed of an epithelium that includes specialized taste buds, the basal lamina, and a lamina propria core with matrix molecules, fibroblasts, nerves, and vessels. Because taste organs are dynamic in cell biology and sensory function, homeostasis requires tight regulation in specific compartments or niches. Recently, the Hedgehog (Hh) pathway has emerged as an essential regulator that maintains lingual taste papillae, taste bud and progenitor cell proliferation and differentiation, and neurophysiological function. Activating or suppressing Hh signaling, with genetic models or pharmacological agents used in cancer treatments, disrupts taste papilla and taste bud integrity and can eliminate responses from taste nerves to chemical stimuli but not to touch or temperature. Understanding Hh regulation of taste organ homeostasis contributes knowledge about the basic biology underlying taste disruptions in patients treated with Hh pathway inhibitors.
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Affiliation(s)
- Charlotte M Mistretta
- Department of Biologic and Materials Sciences, School of Dentistry, University of Michigan, Ann Arbor, Michigan 48109;
| | - Archana Kumari
- Department of Biologic and Materials Sciences, School of Dentistry, University of Michigan, Ann Arbor, Michigan 48109;
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21
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Shandilya J, Gao Y, Nayak TK, Roberts SGE, Medler KF. AP1 transcription factors are required to maintain the peripheral taste system. Cell Death Dis 2016; 7:e2433. [PMID: 27787515 PMCID: PMC5133999 DOI: 10.1038/cddis.2016.343] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 08/30/2016] [Accepted: 09/26/2016] [Indexed: 01/07/2023]
Abstract
The sense of taste is used by organisms to achieve the optimal nutritional requirement and avoid potentially toxic compounds. In the oral cavity, taste receptor cells are grouped together in taste buds that are present in specialized taste papillae in the tongue. Taste receptor cells are the cells that detect chemicals in potential food items and transmit that information to gustatory nerves that convey the taste information to the brain. As taste cells are in contact with the external environment, they can be damaged and are routinely replaced throughout an organism's lifetime to maintain functionality. However, this taste cell turnover loses efficiency over time resulting in a reduction in taste ability. Currently, very little is known about the mechanisms that regulate the renewal and maintenance of taste cells. We therefore performed RNA-sequencing analysis on isolated taste cells from 2 and 6-month-old mice to determine how alterations in the taste cell-transcriptome regulate taste cell maintenance and function in adults. We found that the activator protein-1 (AP1) transcription factors (c-Fos, Fosb and c-Jun) and genes associated with this pathway were significantly downregulated in taste cells by 6 months and further declined at 12 months. We generated conditional c-Fos-knockout mice to target K14-expressing cells, including differentiating taste cells. c-Fos deletion caused a severe perturbation in taste bud structure and resulted in a significant reduction in the taste bud size. c-Fos deletion also affected taste cell turnover as evident by a decrease in proliferative marker, and upregulation of the apoptotic marker cleaved-PARP. Thus, AP1 factors are important regulators of adult taste cell renewal and their downregulation negatively impacts taste maintenance.
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Affiliation(s)
- Jayasha Shandilya
- Department of Biological Sciences, University at Buffalo, Buffalo, NY 14260, USA
| | - Yankun Gao
- Department of Biological Sciences, University at Buffalo, Buffalo, NY 14260, USA
| | - Tapan K Nayak
- Department of Physiology & Biophysics, University at Buffalo, Buffalo, NY 14214, USA
| | - Stefan G E Roberts
- Department of Biological Sciences, University at Buffalo, Buffalo, NY 14260, USA
| | - Kathryn F Medler
- Department of Biological Sciences, University at Buffalo, Buffalo, NY 14260, USA
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22
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Honda K, Tomooka Y. Nerve-independent and ectopically additional induction of taste buds in organ culture of fetal tongues. In Vitro Cell Dev Biol Anim 2016; 52:911-919. [PMID: 27368433 DOI: 10.1007/s11626-016-0067-4] [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: 04/19/2016] [Accepted: 06/20/2016] [Indexed: 10/21/2022]
Abstract
An improved organ culture system allowed to observe morphogenesis of mouse lingual papillae and taste buds relatively for longer period, in which fetal tongues were analyzed for 6 d. Taste cells were defined as eosinophobic epithelial cells expressing CK8 and Sox2 within lingual epithelium. Addition of glycogen synthase kinase 3 beta inhibitor CHIR99021 induced many taste cells and buds in non-gustatory and gustatory stratified lingual epithelium. The present study clearly demonstrated induction of taste cells and buds ectopically and without innervation.
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Affiliation(s)
- Kotaro Honda
- Graduate School of Industrial Science and Technology, Department of Biological Science and Technology, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo, 125-8585, Japan.
| | - Yasuhiro Tomooka
- Graduate School of Industrial Science and Technology, Department of Biological Science and Technology, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo, 125-8585, Japan
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23
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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.
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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
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24
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Gaillard D, Xu M, Liu F, Millar SE, Barlow LA. β-Catenin Signaling Biases Multipotent Lingual Epithelial Progenitors to Differentiate and Acquire Specific Taste Cell Fates. PLoS Genet 2015; 11:e1005208. [PMID: 26020789 PMCID: PMC4447363 DOI: 10.1371/journal.pgen.1005208] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2014] [Accepted: 04/13/2015] [Indexed: 11/29/2022] Open
Abstract
Continuous taste bud cell renewal is essential to maintain taste function in adults; however, the molecular mechanisms that regulate taste cell turnover are unknown. Using inducible Cre-lox technology, we show that activation of β-catenin signaling in multipotent lingual epithelial progenitors outside of taste buds diverts daughter cells from a general epithelial to a taste bud fate. Moreover, while taste buds comprise 3 morphological types, β-catenin activation drives overproduction of primarily glial-like Type I taste cells in both anterior fungiform (FF) and posterior circumvallate (CV) taste buds, with a small increase in Type II receptor cells for sweet, bitter and umami, but does not alter Type III sour detector cells. Beta-catenin activation in post-mitotic taste bud precursors likewise regulates cell differentiation; forced activation of β-catenin in these Shh+ cells promotes Type I cell fate in both FF and CV taste buds, but likely does so non-cell autonomously. Our data are consistent with a model where β-catenin signaling levels within lingual epithelial progenitors dictate cell fate prior to or during entry of new cells into taste buds; high signaling induces Type I cells, intermediate levels drive Type II cell differentiation, while low levels may drive differentiation of Type III cells. Taste is a fundamental sense that helps the body determine whether food can be ingested. Taste dysfunction can be a side effect of cancer therapies, can result from an alteration of the renewal capacities of the taste buds, and is often associated with psychological distress and malnutrition. Thus, understanding how taste cells renew throughout adult life, i.e. how newly born cells replace old cells as they die, is essential to find potential therapeutic targets to improve taste sensitivity in patients suffering taste dysfunction. Here we show that a specific molecular pathway, Wnt/β-catenin signaling, controls renewal of taste cells by regulating separate stages of taste cell turnover. We show that activating this pathway directs the newly born cells to become primarily a specific taste cell type whose role is to support the other taste cells and help them work efficiently.
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Affiliation(s)
- Dany Gaillard
- Department of Cell & Developmental Biology, and the Rocky Mountain Taste & Smell Center, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - Mingang Xu
- Department of Dermatology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
- Department of Cell & Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Fei Liu
- Institute for Regenerative Medicine at Scott & White Hospital, Texas A&M University System Health Science Center, Temple, Texas, United States of America
| | - Sarah E. Millar
- Department of Dermatology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Linda A. Barlow
- Department of Cell & Developmental Biology, and the Rocky Mountain Taste & Smell Center, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
- * E-mail:
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25
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Castillo D, Seidel K, Salcedo E, Ahn C, de Sauvage FJ, Klein OD, Barlow LA. Induction of ectopic taste buds by SHH reveals the competency and plasticity of adult lingual epithelium. Development 2014; 141:2993-3002. [PMID: 24993944 DOI: 10.1242/dev.107631] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Taste buds are assemblies of elongated epithelial cells, which are innervated by gustatory nerves that transmit taste information to the brain stem. Taste cells are continuously renewed throughout life via proliferation of epithelial progenitors, but the molecular regulation of this process remains unknown. During embryogenesis, sonic hedgehog (SHH) negatively regulates taste bud patterning, such that inhibition of SHH causes the formation of more and larger taste bud primordia, including in regions of the tongue normally devoid of taste buds. Here, using a Cre-lox system to drive constitutive expression of SHH, we identify the effects of SHH on the lingual epithelium of adult mice. We show that misexpression of SHH transforms lingual epithelial cell fate, such that daughter cells of lingual epithelial progenitors form cell type-replete, onion-shaped taste buds, rather than non-taste, pseudostratified epithelium. These SHH-induced ectopic taste buds are found in regions of the adult tongue previously thought incapable of generating taste organs. The ectopic buds are composed of all taste cell types, including support cells and detectors of sweet, bitter, umami, salt and sour, and recapitulate the molecular differentiation process of endogenous taste buds. In contrast to the well-established nerve dependence of endogenous taste buds, however, ectopic taste buds form independently of both gustatory and somatosensory innervation. As innervation is required for SHH expression by endogenous taste buds, our data suggest that SHH can replace the need for innervation to drive the entire program of taste bud differentiation.
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Affiliation(s)
- David Castillo
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO 80045, USA Rocky Mountain Taste and Smell Center, University of Colorado School of Medicine, Aurora, CO 80045, USA Graduate Program in Cell Biology, Stem Cells and Development, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Kerstin Seidel
- Program in Craniofacial and Mesenchymal Biology and Department of Orofacial Sciences, University of California San Francisco, San Francisco, CA 94131, USA
| | - Ernesto Salcedo
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO 80045, USA Rocky Mountain Taste and Smell Center, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Christina Ahn
- Department of Molecular Biology, Genentech Inc., South San Francisco, CA 94080, USA
| | | | - Ophir D Klein
- Program in Craniofacial and Mesenchymal Biology and Department of Orofacial Sciences, University of California San Francisco, San Francisco, CA 94131, USA Department of Pediatrics, University of California San Francisco, San Francisco, CA 94131, USA Institute for Human Genetics, University of California San Francisco, San Francisco, CA 94131, USA
| | - Linda A Barlow
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO 80045, USA Rocky Mountain Taste and Smell Center, University of Colorado School of Medicine, Aurora, CO 80045, USA Graduate Program in Cell Biology, Stem Cells and Development, University of Colorado School of Medicine, Aurora, CO 80045, USA
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26
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Miura H, Scott JK, Harada S, Barlow LA. Sonic hedgehog-expressing basal cells are general post-mitotic precursors of functional taste receptor cells. Dev Dyn 2014; 243:1286-97. [PMID: 24590958 DOI: 10.1002/dvdy.24121] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Revised: 02/13/2014] [Accepted: 02/13/2014] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND Taste buds contain ∼60 elongate cells and several basal cells. Elongate cells comprise three functional taste cell types: I, glial cells; II, bitter/sweet/umami receptor cells; and III, sour detectors. Although taste cells are continuously renewed, lineage relationships among cell types are ill-defined. Basal cells have been proposed as taste bud stem cells, a subset of which express Sonic hedgehog (Shh). However, Shh+ basal cells turn over rapidly suggesting that Shh+ cells are post-mitotic precursors of some or all taste cell types. RESULTS To fate map Shh-expressing cells, mice carrying ShhCreER(T2) and a high (CAG-CAT-EGFP) or low (R26RLacZ) efficiency reporter allele were given tamoxifen to activate Cre in Shh+ cells. Using R26RLacZ, lineage-labeled cells occur singly within buds, supporting a post-mitotic state for Shh+ cells. Using either reporter, we show that Shh+ cells differentiate into all three taste cell types, in proportions reflecting cell type ratios in taste buds (I > II > III). CONCLUSIONS Shh+ cells are not stem cells, but are post-mitotic, immediate precursors of taste cells. Shh+ cells differentiate into each of the three taste cell types, and the choice of a specific taste cell fate is regulated to maintain the proper ratio within buds.
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Affiliation(s)
- Hirohito Miura
- Department of Oral Physiology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Kagoshima, Japan
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27
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Cai H, Daimon CM, Cong WN, Wang R, Chirdon P, de Cabo R, Sévigny J, Maudsley S, Martin B. Longitudinal analysis of calorie restriction on rat taste bud morphology and expression of sweet taste modulators. J Gerontol A Biol Sci Med Sci 2013; 69:532-44. [PMID: 24077597 DOI: 10.1093/gerona/glt129] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Calorie restriction (CR) is a lifestyle intervention employed to reduce body weight and improve metabolic functions primarily via reduction of ingested carbohydrates and fats. Taste perception is highly related to functional metabolic status and body adiposity. We have previously shown that sweet taste perception diminishes with age; however, relatively little is known about the effects of various lengths of CR upon taste cell morphology and function. We investigated the effects of CR on taste bud morphology and expression of sweet taste-related modulators in 5-, 17-, and 30-month-old rats. In ad libitum (AL) and CR rats, we consistently found the following parameters altered significantly with advancing age: reduction of taste bud size and taste cell numbers per taste bud and reduced expression of sonic hedgehog, type 1 taste receptor 3 (T1r3), α-gustducin, and glucagon-like peptide-1 (GLP-1). In the oldest rats, CR affected a significant reduction of tongue T1r3, GLP-1, and α-gustducin expression compared with age-matched AL rats. Leptin receptor immunopositive cells were elevated in 17- and 30-month-old CR rats compared with age-matched AL rats. These alterations of sweet taste-related modulators, specifically during advanced aging, suggest that sweet taste perception may be altered in response to different lengths of CR.
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Affiliation(s)
- Huan Cai
- *These authors contributed equally to this work
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Takeda N, Jain R, Li D, Li L, Lu MM, Epstein JA. Lgr5 Identifies Progenitor Cells Capable of Taste Bud Regeneration after Injury. PLoS One 2013; 8:e66314. [PMID: 23824276 PMCID: PMC3688887 DOI: 10.1371/journal.pone.0066314] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Accepted: 05/04/2013] [Indexed: 11/18/2022] Open
Abstract
Taste buds are composed of a variety of taste receptor cell types that develop from tongue epithelium and are regularly replenished under normal homeostatic conditions as well as after injury. The characteristics of cells that give rise to regenerating taste buds are poorly understood. Recent studies have suggested that Lgr5 (leucine-rich repeat-containing G-protein coupled receptor 5) identifies taste bud stem cells that contribute to homeostatic regeneration in adult circumvallate and foliate taste papillae, which are located in the posterior region of the tongue. Taste papillae in the adult anterior region of the tongue do not express Lgr5. Here, we confirm and extend these studies by demonstrating that Lgr5 cells give rise to both anterior and posterior taste buds during development, and are capable of regenerating posterior taste buds after injury induced by glossopharyngeal nerve transection.
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Affiliation(s)
- Norifumi Takeda
- Department of Cell and Developmental Biology, Perelman School of Medicine at the University of Pennsylvania, Pennsylvania, United States of America
- Penn Cardiovascular Institute, Perelman School of Medicine at the University of Pennsylvania, Pennsylvania, United States of America
- Institute of Regenerative Medicine, Perelman School of Medicine at the University of Pennsylvania, Pennsylvania, United States of America
- * E-mail: (NT); (JAE)
| | - Rajan Jain
- Department of Cell and Developmental Biology, Perelman School of Medicine at the University of Pennsylvania, Pennsylvania, United States of America
- Penn Cardiovascular Institute, Perelman School of Medicine at the University of Pennsylvania, Pennsylvania, United States of America
- Institute of Regenerative Medicine, Perelman School of Medicine at the University of Pennsylvania, Pennsylvania, United States of America
| | - Deqiang Li
- Department of Cell and Developmental Biology, Perelman School of Medicine at the University of Pennsylvania, Pennsylvania, United States of America
- Penn Cardiovascular Institute, Perelman School of Medicine at the University of Pennsylvania, Pennsylvania, United States of America
- Institute of Regenerative Medicine, Perelman School of Medicine at the University of Pennsylvania, Pennsylvania, United States of America
| | - Li Li
- Penn Cardiovascular Institute, Perelman School of Medicine at the University of Pennsylvania, Pennsylvania, United States of America
| | - Min Min Lu
- Penn Cardiovascular Institute, Perelman School of Medicine at the University of Pennsylvania, Pennsylvania, United States of America
| | - Jonathan A. Epstein
- Department of Cell and Developmental Biology, Perelman School of Medicine at the University of Pennsylvania, Pennsylvania, United States of America
- Penn Cardiovascular Institute, Perelman School of Medicine at the University of Pennsylvania, Pennsylvania, United States of America
- Institute of Regenerative Medicine, Perelman School of Medicine at the University of Pennsylvania, Pennsylvania, United States of America
- * E-mail: (NT); (JAE)
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Li WL, Chen ML, Liu SS, Li GL, Gu TY, Liang P, Qin YM, Zhan YH, Quan Y, Zhang GH. Sweet preference modified by early experience in mice and the related molecular modulations on the peripheral pathway. J Mol Neurosci 2013; 51:225-36. [PMID: 23606220 DOI: 10.1007/s12031-013-0011-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2012] [Accepted: 04/01/2013] [Indexed: 12/19/2022]
Abstract
The sweet taste is of immense interest to scientists and has been intensively studied during the last two decades. However, the sweet preference modification and the related mechanisms are still unclear. In this study, we try to establish a mice model with manipulated sweet taste preference and explore the involved possible molecular mechanisms. The animals were exposed to acesulfame-K via maternal milk during lactation and the sweet preference tests were carried out when they grew to adulthood. Our results showed that the preference thresholds for sweet taste were increased in adults by early acesulfame-K exposure and the preference ratios for sweet tastants at low or preferred concentrations were decreased. Moreover, by means of qRT-PCR and Western blot, we observed the increased expression of leptin receptor Ob-Rb and downregulation of Gα-gustducin protein in the soft palate. Thereby, the sweet taste sensitivity may be modified by early sweetener experience during lactation. Along the peripheral sweet sensory pathway, the sweet regulator receptors Ob-Rb, CB1 and components of sweet transduction signal Gα-gustducin and T1R2 in both the soft palate and tongue may be cooperatively involved in the plastic development of sweet taste.
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Affiliation(s)
- Wei-Li Li
- Sensory Science Laboratory, School of Bioscience and Food Engineering, Changshu Institute of Technology, Nansanhuan Road 99, Changshu, 215500, Jiangsu Province, People's Republic of China
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Perea-Martinez I, Nagai T, Chaudhari N. Functional cell types in taste buds have distinct longevities. PLoS One 2013; 8:e53399. [PMID: 23320081 PMCID: PMC3540047 DOI: 10.1371/journal.pone.0053399] [Citation(s) in RCA: 125] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Accepted: 11/30/2012] [Indexed: 12/21/2022] Open
Abstract
Taste buds are clusters of polarized sensory cells embedded in stratified oral epithelium. In adult mammals, taste buds turn over continuously and are replenished through the birth of new cells in the basal layer of the surrounding non-sensory epithelium. The half-life of cells in mammalian taste buds has been estimated as 8–12 days on average. Yet, earlier studies did not address whether the now well-defined functional taste bud cell types all exhibit the same lifetime. We employed a recently developed thymidine analog, 5-ethynil-2′-deoxyuridine (EdU) to re-evaluate the incorporation of newly born cells into circumvallate taste buds of adult mice. By combining EdU-labeling with immunostaining for selected markers, we tracked the differentiation and lifespan of the constituent cell types of taste buds. EdU was primarily incorporated into basal extragemmal cells, the principal source for replenishing taste bud cells. Undifferentiated EdU-labeled cells began migrating into circumvallate taste buds within 1 day of their birth. Type II (Receptor) taste cells began to differentiate from EdU-labeled precursors beginning 2 days after birth and then were eliminated with a half-life of 8 days. Type III (Presynaptic) taste cells began differentiating after a delay of 3 days after EdU-labeling, and they survived much longer, with a half-life of 22 days. We also scored taste bud cells that belong to neither Type II nor Type III, a heterogeneous group that includes mostly Type I cells, and also undifferentiated or immature cells. A non-linear decay fit described these cells as two sub-populations with half-lives of 8 and 24 days respectively. Our data suggest that many post-mitotic cells may remain quiescent within taste buds before differentiating into mature taste cells. A small number of slow-cycling cells may also exist within the perimeter of the taste bud. Based on their incidence, we hypothesize that these may be progenitors for Type III cells.
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Affiliation(s)
- Isabel Perea-Martinez
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, Florida, United States of America
| | - Takatoshi Nagai
- Department of Biology, Keio University School of Medicine, Yokohama, Japan
| | - Nirupa Chaudhari
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, Florida, United States of America
- Program in Neurosciences, University of Miami Miller School of Medicine, Miami, Florida, United States of America
- * E-mail:
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Moro E, Ozhan-Kizil G, Mongera A, Beis D, Wierzbicki C, Young RM, Bournele D, Domenichini A, Valdivia LE, Lum L, Chen C, Amatruda JF, Tiso N, Weidinger G, Argenton F. In vivo Wnt signaling tracing through a transgenic biosensor fish reveals novel activity domains. Dev Biol 2012; 366:327-40. [PMID: 22546689 DOI: 10.1016/j.ydbio.2012.03.023] [Citation(s) in RCA: 185] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Revised: 03/09/2012] [Accepted: 03/21/2012] [Indexed: 11/30/2022]
Abstract
The creation of molecular tools able to unravel in vivo spatiotemporal activation of specific cell signaling events during cell migration, differentiation and morphogenesis is of great relevance to developmental cell biology. Here, we describe the generation, validation and applications of two transgenic reporter lines for Wnt/β-catenin signaling, named TCFsiam, and show that they are reliable and sensitive Wnt biosensors for in vivo studies. We demonstrate that these lines sensitively detect Wnt/β-catenin pathway activity in several cellular contexts, from sensory organs to cardiac valve patterning. We provide evidence that Wnt/β-catenin activity is involved in the formation and maintenance of the zebrafish CNS blood vessel network, on which sox10 neural crest-derived cells migrate and proliferate. We finally show that these transgenic lines allow for screening of Wnt signaling modifying compounds, tissue regeneration assessment as well as evaluation of potential Wnt/β-catenin genetic modulators.
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Affiliation(s)
- Enrico Moro
- Department of Biomedical Sciences, University of Padova, I-35121 Padova, Italy.
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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.
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Affiliation(s)
- Yu-Kyong Shin
- Laboratory of Clinical Investigation, Diabetes Section, National Institute on Aging, Baltimore, MD 21224, USA
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