A REGULATORY ELEMENT IN THE 5'UTR DIRECTS CELL-SPECIFIC EXPRESSION OF THE MOUSE ALPHA(4) GENE

Transfection experiments showed that the mouse alpha(4) promoter contains a downstream element in its 5'UTR which is essential for efficient promoter activity. DNaseI footprinting and electrophoretic mobility shift assays (EMSA) demonstrated that the region from nt +113 to +148 can bind a cell type-specific factor (MIII-3) present in the alpha(4)m expressing cell line 1,L1210 but not in the non-expressing cell lines A9 and LMTK(-). Two consensus SP1 sites in this 5'UTR were recognised in L1210, A9 and LMTK(-), and with extracts from A9 and LMTK(-), an AP2-like protein was shown to bind a downstream AP2 site. Thus both ubiquitous and cell type-specific factors regulate the expression of alpha(4)m. (C) 1995 Academic Press, Inc.