Cell-specific enhancers in the rat exocrine pancreas.

Pancreatic amylase, chymotrypsin B, and trypsin I genes are specifically expressed in the exocrine pancreas. The 5'-flanking regions of these genes direct preferential expression of a linked reporter function (chloramphenicol acetyltransferase) in the pancreatic exocrine cell line AR4-2J. The sequences upstream of the amylase and chymotrypsin genes that are required for this cell specific activity possess the characteristics of transcriptional enhancers. We have mapped the regions responsible for enhancer activity by deletion analysis. Modification of specific nucleotide sequences within these regions can alter or eliminate enhancer function. Comparison of the 5'-flanking regions of nine genes expressed in the exocrine pancreas identifies a family of short related sequences. These sequences are located within the enhancer regions that we have mapped and may play a role in the regulation of the expression of pancreatic exocrine-specific genes.