FIG. 4.
Regulation of the cyclin D1 promoter by p52 and Bcl-3. (A) Schematic diagram of p100, p52, and the region of the C terminus of p100 used to construct the CT-p100 expression plasmid. (B) Effects of p52, Bcl-3, and CT-p100 expression on cyclin D1 promoter activity. One and a half micrograms of each of the indicated RSV expression plasmids was cotransfected with 1.5 μg of the indicated cyclin D1-luciferase reporter plasmids into H1299w/tp53 cells in the absence of IPTG treatment. Results are expressed as change in activation or repression (n-fold) relative to levels seen in the relevant untreated cell controls. Western blot analysis of p52 expression in nuclear protein extracts from comparably transfected cells is shown inset. luc, luciferase. (C) CT-p100 does not inhibit TNF-α-induced NF-κB transcriptional activity. The 3× κB-luciferase reporter plasmid (1.5 μg) was cotransfected with 1.5 μg of either the CT-p100, SR-IκBα, or control RSV expression plasmid into H1299w/tp53 cells in the absence of IPTG treatment. Luciferase activity was induced by treatment with 10 ng of TNF-α per ml, and cells were harvested 12 h later. Results are expressed as change in activation or repression (n-fold) relative to levels seen in the relevant untreated cell controls.