The cell-specific elastase I enhancer comprises two domains.
Two separate domains within the 134-base-pair rat elastase I enhancer and a third domain at the enhancer-promoter boundary are required for selective expression in pancreatic acinar cells. The domains were detected by a series of 10-base-pair substitution mutations across the elastase I gene regulatory region from positions -200 to -61. The effect of each mutant on the pancreas-specific expression of a linked chloramphenicol acetyltransferase gene was assayed by transfection into pancreatic 266-6 acinar cells and control NIH/3T3 cells. The two enhancer domains are nonredundant, because mutations in either eliminated (greater than 100-fold reduction) expression in 266-6 cells. DNase I protection studies of the elastase I enhancer-promoter region with partially purified nuclear extracts from pancreatic tissue and 266-6 cells revealed nine discrete protected regions (footprints) on both DNA strands. One of three footprints that lie within the two functional domains of the enhancer contained a sequence, conserved among several pancreas-specific genes, which when mutated decreased linked chloramphenicol acetyltransferase expression up to 170-fold in 266-6 cells. This footprint may represent a binding site for one or more pancreas-specific regulatory proteins.
Kruse
F
F
Department of Biochemistry, University of Texas Health Science Center, Dallas 75235.
Komro
C T
CT
Michnoff
C H
CH
MacDonald
R J
RJ
D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D004742:Enhancer Elements, Genetic; D005796:Genes; D005809:Genes, Regulator; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D009154:Mutation; D010179:Pancreas / Q000201:enzymology; D010196:Pancreatic Elastase / Q000235:genetics*; D010190:Pancreatic Neoplasms / Q000201:enzymology; D010957:Plasmids; D051381:Rats; D011919:Rats, Inbred Strains; D014162:Transfection
D010196:Pancreatic Elastase