Taste buds relay taste sensory information to the primary taste neurons but depend on those same neurons for essential components to maintain function. While denervation-induced taste bud degeneration and subsequent regeneration were discovered decades ago, the mechanisms underlying these phenomena (e.g., heterogenous cellular responses to nerve injury and the signaling pathways involved) remain poorly understood. Here, using mouse genetics, nerve injury models, pharmacologic manipulation, and taste bud organoid models, we identify a specific subpopulation of taste cells, predominantly c-Kit-expressing sweet cells, that exhibit superior resistance to nerve injury. We found the c-Kit inhibitor imatinib selectively reduced the number of residual c-Kit-expressing sweet cells at post-operation week 2, subsequently attenuating the re-emergence of other type II cells by post-operation week 4. In taste bud organoids, c-Kit-expressing cells were resistant to R-spondin withdrawal but susceptible to imatinib, while other taste cell types showed the opposite behavior. We also observed a distinct population of residual taste cells that acquired stem-like properties, generating clonal descendent cells among suprabasal keratinocytes independent of c-Kit signaling. Together, our findings reveal that c-Kit signaling confers resilience on c-Kit-expressing sweet cells and supports the broader reconstruction of taste buds during the later regenerative stage following nerve injury.
Animals ; Taste Buds/metabolism* ; Proto-Oncogene Proteins c-kit/metabolism* ; Mice ; Signal Transduction ; Imatinib Mesylate/pharmacology* ; Mice, Inbred C57BL

The dorsal lingual epithelium, which is composed of taste buds and keratinocytes differentiated from K14⁺ basal cells, discriminates taste compounds and maintains the epithelial barrier. N6-methyladenosine (m⁶A) is the most abundant mRNA modification in eukaryotic cells. How METTL3-mediated m⁶A modification regulates K14⁺ basal cell fate during dorsal lingual epithelium formation and regeneration remains unclear. Here we show knockout of Mettl3 in K14⁺ cells reduced the taste buds and enhanced keratinocytes. Deletion of Mettl3 led to increased basal cell proliferation and decreased cell division in taste buds. Conditional Mettl3 knock-in mice showed little impact on taste buds or keratinization, but displayed increased proliferation of cells around taste buds in a protective manner during post-irradiation recovery. Mechanically, we revealed that the most frequent m⁶A modifications were enriched in Hippo and Wnt signaling, and specific peaks were observed near the stop codons of Lats1 and FZD7. Our study elucidates that METTL3 is essential for taste bud formation and could promote the quantity recovery of taste bud after radiation.
Animals ; Epithelium/metabolism* ; Homeostasis ; Methylation ; Methyltransferases/metabolism* ; Mice ; RNA ; Taste Buds/metabolism*

OBJECTIVES: To identify the alternative splicing isoform of mouse sweet taste receptor T1R2, and investigate the effect of lipopolysaccharide (LPS) local injection on T1R2 alternative splicing and the function of sweet taste receptor as one of the bacterial virulence factors. METHODS: After mouse taste bud tissue isolation was conducted, RNA extraction and reverse transcription polymerase chain reaction (PCR) were performed to identify the splicing isoform of T1R2. Heterologous expression experiments RESULTS: T1R2 splicing isoform T1R2_Δe3p formed sweet taste receptors with T1R3, which could not be activated by sweet taste stimuli and significantly downregulated the function of canonical T1R2/T1R3. Local LPS injection significantly increased the expression ratio of T1R2_Δe3p in mouse taste buds. CONCLUSIONS LPS stimulation affects the alternative splicing of mouse sweet taste receptor T1R2 and significantly upregulates the expression of non-functional isoform T1R2_Δe3p, suggesting that T1R2 alternative splicing regulation may be one of the mechanisms by which microbial infection affects host taste perception.
Alternative Splicing ; Animals ; Lipopolysaccharides ; Mice ; Receptors, G-Protein-Coupled/metabolism* ; Taste ; Taste Buds

The nutritional and metabolic status alters the peripheral taste perception and food intake by participating in the modulation of taste information integration. The taste receptors and neuropeptides in the taste buds are the important targets of this modulation process. To explore the effects of nutritional status on the expressions of galanin and its receptors in the taste buds, we compared the mRNA levels of galanin and its specific receptor GalR2 in the taste buds among the high-fat diet induced obese rats (HF), chronically restricted diet rats (CR) and control rats. The high-fat diet, half of chow diet, and normal chow diet were given to HF, CR and control groups for 6 weeks, respectively. The body weight and some metabolic indexes, including blood glucose, triglyceride and cholesterol levels were detected. The mRNA expressions of galanin and its receptors in taste buds were determined using real-time PCR. Results showed that compared with control rats, the body weights, levels of blood glucose and triglyceride were significantly elevated in HF rats; while the mRNA expressions of galanin and GalR2 were dramatically decreased. However, galanin mRNA expression in CR rats was increased to 2.3 times of that in control group. Considering the results obtained from our previous studies, we conclude that the behavioral changes in tasting choice of HF rats may be related to the expressions of galanin and GalR2 in the taste buds. The changes of galanin and GalR2 in taste buds are involved in the peripheral mechanism of nutritional status regulating taste perception and feeding behavior in rats.
Animals ; Body Weight ; Galanin ; metabolism ; Nutritional Status ; RNA, Messenger ; metabolism ; Rats ; Receptor, Galanin, Type 2 ; metabolism ; Taste Buds ; metabolism