Nucleic Acids Research, 1989, Vol. 17, No. 21 8451-8462
© 1989
MOLECULAR BIOLOGY |
Cell-type specificity of regulatory elements identified by linker scanning mutagenesis in the promoter of the chicken lysozyme gene
Institut für Zell- und Tumorbiologje, Deutsches Krebsforschungszentrum Im Neuenheimer Feld 280, D-6900 Heidelberg 1, FRG
*To whom correspondence should be addressed
Received August 30, 1989. Accepted September 29, 1989.
The chicken lysozyme gene is constitutively expressed in macrophages, in oviduct cells its expression is controlled by steroid hormones, and in fibroblasts the gene is not expressed. A fusion gene consisting of promoter sequences of the lysozyme gene from –208 to +15 in front of the chloramphenicol acetyltransferase (CAT) coding region was more than 50 times less active in non-expressing cells as compared to expressing cells. In order to identify the element(s) responsible for this cell-type specificity 31 different linker scanning mutations were generated within this promoter fragment and analyzed by transient transfections in the three types of chicken cells mentioned above. Three mutation sensitive regions located around position –25, –100 and between –158 and –208 were detected in each cell type, however, several LS mutations displayed clear cell-type specific differences in their phenotypic effects. Interestingly, a few LS mutations led to an increase in promoter activity in fibroblasts suggesting that the corresponding wildtype sequences represent binding sites for negatively acting transcription factors.