Our current understanding of the function of salivary gland and their secretory products in oral health and disease has improved significantly. However, the actual molecular events involved in the control of salivary gland secretion are still poorly understood. A better understanding of the molecular events involved in salivary gland secretion would provide the necessary information to more fully comprehend the possible pathogenesis of various exocrine diseases. The long range objective of this research project is to develop new basic scientific information regarding the actual molecular events that directly control rat parotid exocytosis. Once having gained additional insights into these molecular events, we plan to study human salivary tissue; from normal patients, patients with salivary dysfunction, and from patients with cystic fibrosis. New basic scientific information may provide new insights into the development of new therapeutic approaches from such diseases. Our current research objectives are to study the role of the cAMP dependent and calcium dependent regulatory pathway which control rat parotid exocytosis. We intend to (1) further characterize an integral membrane phosphoprotein (pp26) which appears to be directly involved in regulating rat parotid secretin following B-adrenergic receptor stimulation.l Peptide mapping, and protein sequencing studies will be done. Monospecific antibodies will be developed to localize the pp26 within the secretory cells and these antibodies will also be used to probe the secretory pathway to see if other secretory regulatory proteins can be identified; (2) further characterize the role of the two isozymes of cAMP dependent protein kinase (cA-PK) in regulating amylase secretion and the phosphorylation of pp26. Site specific analogs of cAMP will be used to define the role of type I and type II cA-PK in amylase secretion and (3) begin to evaluate those cellular events that appear to be directly involved in the calcium dependent pathway. These studies will include: (a) determine the intracellular free calcium levels following secretagogue stimulation using Fura-2, (b) determining the cellular calcium-binding proteins, (c) determining the calmodulin-binding proteins, and (d) determining whether any of these proteins are directly involved in secretion. The studies should provide important new scientific information regarding the regulation of exocytosis.
