Proceedings of The Physiological Society

Europhysiology 2018 (London, UK) (2018) Proc Physiol Soc 41, PCA209

Poster Communications

Immortalization of mouse fungiform and circumvallate taste bud cell lines: physiological characterization

A. Hichmai1, A. Dumont2, M. Rialland2, J. Leemput1, N. Khan1

1. Physiologie de la Nutrition & Toxicologie (NUTox), UMR INSERM U1231 Lipides, Université de Bourgogne Franche-Comté, 21000 Dijon, France., Dijon, France. 2. Tumor Immunologie Lab, UMR INSERM U1231 Lipides, Nutrition & Cancer, Université de Bourgogne Franche-Comté, Dijon, France.

Taste buds, localized in the lingual papillae, are responsible for the gustatory perception of several taste modalities such as bitter, sweet, sour, salt and umami. The taste buds are principally localized in three lingual papillae, i.e., fungiform, foliate and circumvallate. The taste buds are composed of 4 taste bud cells types (TBCs) with distinct functions: Type I (glial-like) cells, Types II (taste receptor) cells, Type III (neuronal-like) cell and Type IV (progenitor) cells. The taste receptors for sweet, umami, fat, and bitter are mainly expressed by type II cells. The type 2 taste receptor (T2R) is involved in the perception of bitter taste whereas the heterodimers like T1R2/T1R3 and T1R2/T1R3 detect umami and sweet tastes, respectively. Fat taste, which represents the new sixth taste modality, is detected by CD36, GPR120 and GPR40. T1R and T2R are coupled to a G-protein, called gustducin. Generally, in order to study the physiological aspects of taste signaling, the TBCs are used as a primary cell culture. However, these cells degenerate and lose their properties as a function of time in the cultured conditions. To the best of our knowledge, there is no mouse taste bud cell line available for conducting in vitro experiments. Therefore, there is a dire need to establish an immortalized mouse taste bud cell line that must express all the physiological characteristics. In the present piece of investigation, we isolated the TBCs from circumvallate and fungiform papillae from 2-month old male mice of C57BL6 strain. The freshly isolated TBCs were treated by elastase and dispase mixtures, then cultured for 24 h in a medium that contained Iscove's DMEM and MCDB-153 media with 10% fetal bovine serum and a cocktail of antibiotics. The cells were transfected with m-tert retrovirus. After 15 day of culture, several clones were picked up and expanded until their characterization. We employed western blot and RT-qPCR techniques for the analysis of taste bud cell markers. We observed that some clones expressed sweet and umami (T1R1/T1R2/T1R3), bitter (T2R16/T2R38) and lipido-receptors (CD36 and GPR120). In addition, these cells expressed both gustducin protein, responsible for signal transduction. Furthermore, we conducted calcium signaling studies in Fura-2/AM loaded cells and observed that the immortalized mouse taste bud cells responded to the agonists of all the taste modalities. In conclusion, the phenotype of the immortalized mouse taste bud cells closely resembles to taste-responding type II TBCs. As the mouse model is largely used for laboratory experiments, the immortalized mouse TBCs, developed and characterized by us, for the first time, can be used for in vitro investigations to study the mechanism of action of tastants.

Where applicable, experiments conform with Society ethical requirements