Saliva contains a broad spectrum of proteins which are known to play a pivotal role in maintaining the integrity of the hard and soft oral tissues. Many of the proteins secreted from the parotid gland are glycoproteins and carry N-linked oligosaccharides. To study the mechanisms involved in synthesis, processing and secretion of N-linked secretory glycoproteins we have utilized in vitro cell and microsomal membrane preparations from rat parotid glands. We have previously demonstrated that Beta-adrenergic receptor stimulation increased protein N-glycosylation through a cAMP-mediated mechanism. This appears to be due to increased synthesis and utilization of oligosaccharide-PP-dolichol and enhanced activity of specific glycosyltransferases. We have also shown that Beta-adrenoreceptor stimulation modulates the rate of processing of N-linked oligosaccharides in a single high molecular weight (220kd) secretory glycoprotein. During the present reporting period we have 1) progressed in our studies on salivary protein-bacterial interaction after treatment with Beta-adrenergic drugs in rats in vivo; 2) examined the role of oligosaccharyltransferase in the enhancement of N-linked glycosylation seen in rat parotid acinar cells after Beta-adrenoreceptor stimulation; 3) observed similar increases in protein N-glycosylation after Beta-adrenergic receptor stimulation in human parotid acinar cells as in rat cells; 4) utilized two sympathetic denvervation models, surgical and pharmacological (reserpine), to further examine Beta-receptor regulation of salivary gland function; 5) observed decreased (about 30%) protein N-glycosylation with aging in rats; this change being associated with decreased (about 50%) Man-P-Dol synthase activity; 6) demonstrated that cAMP enhanced glycosylation in many cell types other than parotid, including human foreskin fibroblasts, chinese hamster ovary (CHO) cells, bovine capillary endothelial cells and lacrimal gland acinar cells; 7) continued studies on the characterization of the four secretory glycoproteins (220, 38, 32, 17kd) exhibiting glycosylation changes.
