Lineage tracing of Twist2-expressing cells in mouse taste buds.

OBJECTIVES It is widely accepted that Taste bud cells originate from the epithelium; however, evidence indicates that these cells are also derived from the mesenchyme beneath the epithelium. In this study, the cell lineage expressing Twist2, a transcription factor that is specifically expressed in the mesenchyme within taste buds, were examined to gain a deeper understanding of its biological characteristics.

METHODS Immunohistochemical analyses and taste organoid cultures were performed using Twist2 lineage-tracing reporter mice (Twist2-Cre mice crossed with tdTomato mice) to identify Twist2-derived cells in taste buds. The transgenic mice were harvested at 7, 14, and 21 days, post-administration of 5-ethynyl-2'-deoxyuridine (EdU), to assess the label retention of Twist2-derived cells.

RESULTS tdTomato-positive cells expressed Type III taste cell markers in the taste papillae and soft palate. tdTomato-positive organoids derived from the circumvallate papilla contained numerous taste bud cells. EdU analysis revealed that tdTomato-positive cells expressing a Type III taste cell marker persisted for longer than tdTomato-negative cells that expressed the same marker. In addition, almost all the long-term cultured tdTomato-positive organoids contained cells expressing a Type II taste cell marker.

CONCLUSIONS The findings support the hypothesis that mesenchymal cells contribute to the taste bud cell population.