The long-term objectives are (1) to understand the structure, function and regulation of the tissue-specific inducible multigene families which encode proline-rich proteins, and (2) to determine the structure and conformation of proline-rich proteins.
Specific aims i nclude (1) cloning and sequencing cDNAs and genes from rat, mouse and hamster that encode proline-rich proteins, (2) transfecting appropriate cell lines with proline-rich protein genes, or chimeric genes of various constructions and deletions, and evaluating the induction of proline-rich proteins in transfected cell lines by various agents, (3) elucidating the mechanisms of induction, or modulation of transcription of these tissue-specific multigene families by using transfected cell lines or primary parotid gland cell cultures, and studies on chromatin changes, (4) studying the unusual differences in cell-free translation patterns of RNAs isolated from various mouse strains after isoproterenol treatment, (5) synthesising chemically the tandemly repeated peptide of the proline-rich glycoprotein GP66sm, (6) examining the synthetic peptide and polymers of the peptide by 13C-NMR to evaluate cis/trans isomerization under various conditions of solvent, pH and temperature, (7) investigating the mechanisms of proline-rich protein and tannin binding and interaction, and (8) continuing studies on the structural analysis and biosynthesis of the oligosaccharide components of GP66sm and other glycoproteins. The unique appearance of proline-rich proteins at high levels in human saliva suggests a functional role in the oral cavity or elsewhere in the gastrointestinal tract. Of special importance is the dramatic induction of proline-rich proteins in the parotid and submandibular glands of rats, mice and hamsters. Feeding tannins induces the same gene expression in rats and mice, but not in hamsters and changes are observed only in the parotid glands. There is clear evidence that the induction by tannins or other polyphenols protects the animals from the detrimental effects of tannins on nutrition and weight gain. Tannins are known carcinogens and populations that consume high-tannin foods or chew betel nuts have a high incidence of oral and esophogeal cancer. Proline-rich proteins have a very high affinity for tannins, and these unusual proteins may have an anti-carcinogenic role. The general methods to be used include cloning, recombinant DNA procedures, nucleotide and peptide sequencing cell transfections, gene induction and activation analyses, and NMR analysis of peptides, proteins and oligosaccharides.
