Changes in the dietary content of fat, starch and protein result in adaptive changes in the synthesis, activity and mRNA levels of the pancreatic digestive enzymes: lipase, amylase, trypsinogen and chymotrypsinogen. The mechanisms of these adaptations are unknown, but represent important examples of nutrient interaction in the regulation of gene expression. The mechanisms of adaptation of pancreatic lipase and amylase will be studied in primary serum-free cultures of acinar cells that maintain differentiated ultrastructure and secretory responsiveness in culture. The initial focus of these studies will be to improve the maintenance of tissue specific gene expression in the culture system. The hypothesis that extracellular matrix interacts in vitro with cells to restore tissue specific gene transcription and its regulation will be examined. The content, mRNA levels and mRNA transcription rates of tissue specific genes (elastase, amylase and lipase) will be determined in cells cultured with or without extracellular matrix. Conditions that maximize tissue- specific gene expression will be used for further studies on dietary adaptation. The possible anticoordinate regulation of amylase and lipase will be evaluated by determining the effects of proposed regulators on the content and synthesis of both enzymes in cultured acinar cells. The role of glucose, and its interaction with insulin and gastrointestinal hormones, in the regulation of both enzymes will be investigated. The effects of fatty acids and their interaction with secretin and ketones in the regulation of both enzymes will be examined in cultured cells. The interaction of glucose, insulin, ketones, fatty acids, secretin and cholecystokinin will be examined in the regulation of both enzymes. The effects of these nutrients, metabolites and hormones will be measured on cellular DNA, proteins, amylase and lipase. The rates of synthesis of amylase and lipase will,be determined by labelled amino acid incorporation into each protein. Cellular glucose utilization (uptake and oxidation) as well as fatty acid and ketone oxidation will be measured. To determine the mechanisms of regulatory agents identified in these studies, amylase and lipase mRNAs will be quantitated by cDNA hybridization. Once the cellular mechanisms of adaptation are known the development of these regulatory mechanisms and the effects of perinatal nutrition on this development will be studied.
| Hirschi, K K; Vasiloudes, P; Brannon, P M (1994) Effects of secretin and caerulein on pancreatic digestive enzymes in cultured rat acinar cells. Pancreas 9:91-100 |
| Tsai, A; Cowan, M R; Johnson, D G et al. (1994) Regulation of pancreatic amylase and lipase gene expression by diet and insulin in diabetic rats. Am J Physiol 267:G575-83 |
| Hirschi, K K; Kenny, S; Justice, J D et al. (1991) Effects of secretin and caerulein on enzymes of cultured pancreatic acinar cells. In Vitro Cell Dev Biol 27A:660-4 |
| Hirschi, K K; Sabb, J E; Brannon, P M (1991) Effects of diet and ketones on rat pancreatic lipase in cultured acinar cells. J Nutr 121:1129-34 |
