Transcriptional activity of reporter constructs driven by Ig regulatory elements or the HSV-tk promoter.

(A) Namalwa, BJA-B, DG-75, Raji and Jok-1 cells (control B-cell lines), and L428 and KM-H2 cells (HD cell lines) were transfected with the wild type promoter-driven luciferase reporters (μET1) and the mutant promoter-driven reporters (μET1m). The activity of the mutant promoters was set to 1 for all cell lines and the specific activity of the wild-type promoter-driven reporter is shown as relative activity. All transfections were independently repeated minimally 3 times and in all cases a tk-driven renilla-luciferase reporter was co-transfected to correct for differences in transfection efficiencies. (B) Similar transfection as in A with luciferase reporters containing the intact tk-promoter (tk.luc, −109 to +52) or a truncated version of this promoter (pTATA, −38 to +52). The activity of the truncated promoter was set to 1 and tk.luc activity is shown relative to pTATA. (C) Schematic representation of the reporter constructs used in A and B. O = octamer motif (the mutated octamer motif is indicated by the crossed out symbol); T = TATA box. The enhancer fragment is not drawn to scale (the 1000 bp XbaI fragment of the enhancer was used).40