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Dev Dyn. 2014 Oct;243(10):1286-97. doi: 10.1002/dvdy.24121. Epub 2014 Mar 21.

Sonic hedgehog-expressing basal cells are general post-mitotic precursors of functional taste receptor cells.

Author information

1
Department of Oral Physiology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Kagoshima, Japan.

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.

KEYWORDS:

Cre recombinase; Shh; cell lineage; lineage tracing; molecular genetics; mouse; regeneration; tamoxifen; taste bud

PMID:
24590958
PMCID:
PMC4152395
DOI:
10.1002/dvdy.24121
[Indexed for MEDLINE]
Free PMC Article

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