Expression of Mash1 in basal cells of rat circumvallate taste buds is dependent upon gustatory innervation

Mash1, a mammalian homologue of the Drosophila achaete-scute proneural gene complex, plays an essential role in differentiation of subsets of peripher al neurons. In this study, using RT-PCR and in situ RT-PCR, we investigated if Mash1 gene expression occurs in rat taste buds. Further, we examined dy namics of Mash1 expression in the process of degeneration and regeneration in denervated rat taste buds, In rat tongue epithelium, Mash1 gene expressi on is confined to circumvallate, foliate, and fungiform papilla epithelia t hat include taste buds, In taste buds, Mash1-expressing cells are round cel ls in the basal compartment, In contrast, the mature taste bud cells do not express the Mash1 gene. Denervation and regeneration experiments show that the expression of Mash1 requires gustatory innervation. We conclude that M ash1 is expressed in cells of the taste bud lineage, and that the expressio n of Mash1 in rat taste buds is dependent upon gustatory innervation. (C) 1 999 Federation of European Biochemical Societies.