Chemical sense organs, such as taste, are part of a complicated, but integrated, system of tissues. Accessory glands perform critical peri-receptor functions through the tissue-specific expression of unique gene products. The numerous taste cells that are localized in the circumvallate papillae are constantly bathed by secretions of the von Ebners glands. Among the functions assigned to von Ebner (VEG) secretory proteins is their postulated role in the chemical sense of taste. The Principal Investigator hypothesizes that VEG proteins interact with a variety of sapid molecules. For example, bitter tastants may require a VEG protein for presentation to, and/or clearance from, the taste receptor. Other potential functions for VEG proteins include preserving mucosal integrity and chemical modification of tastants. To test this hypothesis, studies are proposed to characterize the T8-4 cDNA and gene which encodes a unique von Ebner gland protein. T8-4 was recovered from a cDNA library made to mouse circumvallate papillae mRNA by using subtracted hybridization probes. Studies are also proposed to isolate additional unique VEG-specific clones and test them using the same methodology. VEG cell lines will also be isolated from H-2KbtsA58 transgenic stocks (Immortomouse) and characterized for their capacity to engage in the expression of VEG specific markers of differentiation. Molecular genetic studies will be used to seek an association between VEG cDNA clones with mouse strains harboring known genetic predilections for altered taste sensitivities. The T8-4 VEG-specific cDNA will be expressed in bacteria as a fusion protein and used for binding measurement to presumptive tastant ligands and in tests for VEG-protein directed modification of tastant ligands. In addition, bacteria produced T8-4 protein will be used as an immunogen to create antibodies in order to study VEG-protein secretory pathways. Progress by the research team includes the identification of a VEG-specific cDNA clone termed T8-4. T8-4 is shown to be expressed exclusively by VEG acinar cells as a mRNA of approximately 2100 nt. Nucleotide sequence obtained for T8-4 suggests it is unrelated to the cDNAs described by Schmale, and T8-4 is unrelated to proline rich protein, histidine or statherin. The conceptual translation of T8-4 contains motifs similar to those of proteins with known carrier functions. The research team provides preliminary data and a proposed experimental strategy designed to obtain a better characterization of the VEG products and their potential role in supporting the chemical sense of taste.
| Jitpukdeebodintra, Suwanna; Chai, Yang; Snead, Malcolm L (2002) Developmental patterning of the circumvallate papilla. Int J Dev Biol 46:755-63 |
