Differentially Expressed Genes in Oral Cells and Tissues

Several recent studies have provided a wealth of information on the composition of the proteome of human whole saliva. However, by their nature, these studies can not determine whether the identified proteins are derived from glandular sources or from oral epithelial cells. Objectives: To characterize expression patterns of salivary protein genes and identify those differentially expressed in human submandibular gland (SM), sublingual gland (SL) and gingival epithelium (G). Methods: RNA from SM and SL salivary glands and from normal gingival tissue was subjected to a two step Gene Fishing RT-PCR protocol with 60 different arbitrary primers. Differentially expressed cDNAs were recovered from agarose gels and sequenced. The observed expression patterns of selected genes were then confirmed in PCR reactions using gene specific primers. Results: Most of the arbitrary primers revealed expression patterns of cDNAs similar or identical in the tissues examined. Of the differentially expressed genes identified, some were expressed predominately in SM (such as histatin/statherin), predominately in SL (such as prolactin inducible protein) or predominately in G (such as transglutaminase 3). Other genes had overlapping expression profiles, with some found in SM and SL but not G (such as a serine peptidase inhibitor) or others found in SL and G but not SM (such as the small proline rich protein 3). Conclusion: Many of the proteins identified in the whole saliva proteome likely represent products of both salivary glands and oral epithelial cells. Those which are differentially expressed may have unique and specific functions related to their site of synthesis.

Supported by NIH DE11691 and DE14080.