The long-term objective is to understand the molecular mechanisms that different types of morphologically and physiologically heterogeneous taste cells utilize in receiving, processing and transmitting gustatory signals. Using a set of known genes we have successfully applied single cell RT-PCR amplification and filter hybridization methods to determine limited gene expression patterns for some taste cells, and to identify several taste cell type selective signaling elements thought to play a critical role in bitter sensation. In this application, we will use single cell RT-PCR products to probe DNA arrays to establish global gene expression profiles for many taste cells, to determine and predict taste cell types/subtypes based on their expression profiles, to identify additional taste type or subtype- selective genes or clusters of genes that define this type or subtype's physiological functions in taste perception. The specific goals of this application are: 1. To generate DNA probes from taste buds, filiform papillae and 100 individual taste cells using both an aRNA amplification method and a modified single cell RT-PCR procedure; 2. To screen genome-wide DNA arrays with both taste bud and filiform probes, to identify and re-array genes that are enriched in taste buds over filiform papillae to prepare taste DNA arrays (taste chips); 3. To screen the taste chips in pair wise fashion with a taste bud probe paired with one of the 100 single taste cell probes to be generated, and to establish the gene expression profiles of the individual taste cells by identifying the expressed genes on the taste chips in each single cell probe, to determine and discover taste cell types or subtypes using unsupervised partitional clustering method, and to identify additional gene classifiers with the neighborhood analysis method. The results of these studies will contribute to the development of new technologies in pursuing post-genomic biomedical research, provide genetic bases for taste cell classification and yield significant novel insights into the molecular mechanisms underlying taste transduction. The knowledge gained from this application should further our understanding of genetic differences in taste sensitivity, and the gustatory and metabolic disorders such as malgeusia, dysgeusia and cachexia.
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