Erb and c-Kit receptors have distinctive patterns of expression in adult and developing taste papillae and taste buds.

Twenty four different protein tyrosine kinases (PTKs) were amplified from a taste-enriched cDNA library using PCR. The expression of four protein tyrosine kinase receptors (EGFR, ErbB2, ErbB3, and c-kit) was examined in adult and developing rat taste papillae. All four of these receptors were expressed in overlapping populations of differentiated taste cells within adult taste buds. Taste bud basal cells were ErbB2(+) but did not express the other Erb receptors. During prenatal development, the Erb receptors were expressed extensively in the basal cells around developing papillae, and ErbB2 and c-kit immunoreactive neuronal fibers were seen in close association with taste papillae. In early postnatal stages, ErbB2(+) and c-kit(+) neuronal fibers were often seen entering the taste papillae epithelium, where new taste buds form, and by postnatal day 2 (P2), individual ErbB2(+) and c-kit(+) cells were seen in this region as well. Between P3 and P8, c-kit was highly expressed at the bottom of foliate papillae trenches. The extensive expression of the Erb and c-kit receptors in adult taste buds and in and around developing papillae suggests that these receptors may play a role in the prenatal and postnatal development of gustatory papillae and taste buds.