Abstract
Taste bud cells arise from local epithelial stem cells in the oral cavity and are continuously replaced by newborn cells throughout an animal’s life. However, little is known about the molecular and cellular mechanisms of taste cell turnover. Recently, it has been demonstrated that SOX2, a transcription factor expressed in epithelial stem/progenitor cells of the oral cavity, regulates turnover of anterior tongue epithelium including gustatory and non-gustatory papillae. Yet, the role of SOX2 in regulating taste cell turnover in the posterior tongue is unclear. Prompted by the fact that there are regional differences in the cellular and molecular composition of taste buds and stem/progenitor cells in the anterior and posterior portions of tongue, which are derived from distinct embryonic origins, we set out to determine the role of SOX2 in epithelial tissue homeostasis in the posterior tongue. Here we report the differential requirement of SOX2 in the stem/progenitor cells for the normal turnover of lingual epithelial cells in the posterior tongue. Sox2 deletion in the stem/progenitor cells neither induced active caspase 3-mediated apoptotic cell death nor altered stem/progenitor cell population in the posterior tongue. Nevertheless, morphology and molecular feature of non-gustatory epithelial cells were impaired in the circumvallate papilla but not in the filiform papillae. Remarkably, taste buds became thinner, collapsed, and undetectable over time. Lineage tracing of Sox2-deleted stem/progenitor cells demonstrated an almost complete lack of newly generated basal precursor cells in the taste buds, suggesting mechanistically that Sox2 is involved in determining stem/progenitor cells to differentiate to gustatory lineage cells. Together, these results demonstrate that SOX2 plays key roles in regulating epithelial tissue homeostasis in the posterior tongue, similar but not identical to its function in the anterior tongue.
Highlights
Taste buds comprise tens of cells, including taste receptor cells, to sense different taste qualities [1,2,3]
SOX2 is expressed both in stem/progenitor cells and in a subset of taste bud cells that are continuously replenished from local Sox2+ epithelial stem/progenitor cells
In parallel with the over time decrease of SOX2 immunoreactive signals, KCNQ1 immunoreactive signals that can be observed in almost all taste bud cells were decreased and completely disappeared 14 days after tamoxifen injection (Fig 1), suggesting that taste bud cells were not regenerated after inducing Sox2 deficiency in the stem/progenitor cells
Summary
Taste buds comprise tens of cells, including taste receptor cells, to sense different taste qualities [1,2,3]. In the dorsal tongue of mice, they are localized in the papillary structures, fungiform, foliate, and circumvallate papillae. Fungiform papillae (FuP) are scatterd in the anterior two-. SOX2 for homeostasis of posterior tongue epithelium. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
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