Saliva plays a pivotal role in maintaining the integrity of the hard and soft tissues. Salivary gland cellular activities such as protein exocytosis, synthesis and processing are regulated by beta- adrenergic receptors. To study the mechanisms involved in synthesis, processing and secretion of proteins carrying N-linked to oligosacchrides we have utilized in vitro cell and microsomal membrane preparations from rat parotid glands. We have shown that beta-adrenoreceptor stimulation increased N-linked protein glycosylation through a c-AMP-mediated mechanism. This appears to be due to an increased synthesis and utilization of oligosaccharide-PP-dolichol and enhanced activity of specific glycosyltransferases. In addition beta-adrenoreceptor stimulation modulates the rate of processing on a high molecular weight (220kD) secretory glycoprotein. We have also shown that changes in parotid saliva protein composition after treatment with beta- adrenergic drugs influence the adherence and aggregation of oral bacteria. During this reporting period we have 1) characterized the oligosaccharides associated with four secretory glycoproteins (220,38,32 and 17kD); 2) isolated secretory granules and secretory granule membranes of a high purity and partially characterized these membranes; 3) constructed cDNA libraries from Poly(A) RNA isolated from control and isoproterenol treated rat parotid glands; 4) synthesized oligonucleotide probes corresponding to the parotid proline rich protein (PRP): 5) identified seven positive PRP clones and 6) demonstrated that beta-adrenergic receptor stimulation regulates protooncogene expression (c-fos, c-myc, p 53, c-abl and c-sis) in rat parotid acinar cells.
