The Expression of Protocadherin 20 (Pcdh 20) in Mouse Taste Buds

Objectives: Taste information is detected by taste cells and then transmitted to the brain through the taste nerve fibers. According to our previous data, taste quality specific coding might exist between taste cells and nerve fibers. However, underlying molecular mechanisms remain unclear. The purpose of this study is to identify the guidance molecules regulating the taste quality specific coding mechanisms.
Methods: C57BL/6J (8-10 weeks) mice were used in this experiment. Total RNA were extracted from taste buds and taste-related cranial ganglia. The gene expression profile was examined by using GeneChip and RT-PCR analyses. In addition, in situ hybridization and immunohistochemistry were performed on these tissues.
Results: GeneChip analysis showed that several cadherins, important regulators for synapse guidance, were expressed in the taste buds and the taste neurons. Among them, protocadherin 20 (Pcdh20) mRNA was highly expressed in the taste buds. In situ hybridization and immunohistochemical analyses showed that Pcdh20 was expressed in a subset of taste cells, especially co-expressed with T1R3 (sweet sensitive taste cell marker), but not with gustducin (bitter sensitive taste cell marker) or Car4 (sour sensitive taste cell marker).
Conclusions: These result suggest that Pcdh 20 could be involved in the specific connection of sweet taste cells with sweet-coding neuron.