A NEGATIVE REGULATORY ELEMENT OF THE MACROPHAGE-SPECIFIC HUMAN MANNOSE RECEPTOR GENE REPRESSES ITS EXPRESSION IN NONMYELOID CELLS

We have cloned the putative promoter of the human mannose receptor gen e using the ligation-mediated polymerase chain reaction. This modified polymerase chain reaction method depends upon the ligation of restric ted genomic DNA fragments to a sequence of DNA containing a generic pr imer site. Approximately 400 bp of genomic DNA sequence immediately up stream from the 5' end of the lectin gene was amplified with this stra tegy. Primer-extended reverse transcription identified several 5' ends of the mannose receptor mRNA corresponding to differential use of ini tiation transcription sites. DNA sequence analysis of the 5' flanking sequence of the mannose receptor gene indicated the presence of a TATA box and various putative binding sites for several transcription acti vators. The insertion of the sequence into a plasmid containing a prom oterless luciferase reporter gene reveals a promoter activity with a h igh cell type specificity, efficient expression upon transfection into macrophage type cells, and lack of efficiency upon transfection into nonmyeloid cells. A series of deletion mutants reveals that this cell- type-specific promoter activity is mediated by a negative regulatory e lement located at the 5' end of the isolated promoter. (C) 1994 Academ ic Press, Inc.