Deletion analysis of the rodent selenoprotein W promoter

To identify regulatory elements in the rat selenoprotein W (SeW) promoter, 2090, 1265, 741, and 404 base pair truncations of genomic DNA lying immediately upstream of the SeW coding sequence were cloned into a luciferase reporter vector (pGL3-Basic from Promega, Madison, WI, USA). 3656 and 406 base pair mouse SeW promoter constructs were also compared. SeW promoter activity was assayed in two rat cell lines: L8 muscle cells and C6 brain cells. The SeW promoter was 2-7 times more active (p < 0.01) than SV40 promoter. Promoter activity of constructs of the SeW promoter ranging from 200 base pairs to 51 base pairs gradually decreased to zero in brain cells, but fell precipitously to zero in muscle cells. Some truncations stimulated promoter activity, suggesting the full-length promoter may contain binding sites for factors that suppress SeW expression.