FIGURE 4.

Determination of the core promoter of the LAT-miRNA coding sequence. (A) DNA sequence of the P1Δ3′ promoter. White boxes correspond to the 60-bp repeats and sequences shaded in black correspond to nonrepeated sequences. Sequences shaded in gray correspond to the first eight nucleotides of a 60-bp block; p53 responsive elements are indicated in bold. (B,C) Relative luciferase activity obtained with various promoter constructs: [60 bp]₃, [60 bp]₂, or [60 bp]₁ carrying of three, two, or one 60-bp repeats, respectively, and [60 bp] + 8 bp and [60 bp] + 8 bp mut, contain one block of 60 bp with the first eight bases of a second repeat or eight mutated bases (polyG), respectively. The luciferase activities obtained with these constructs were normalized with respect to that of the P1Δ3′luciferase construct. Tests were performed with LMH (B) and 54-O (C) cells. Each value corresponds to the mean of three independent assays performed simultaneously. Error bars indicate the SEM of three replicates. Schematic diagrams of the various promoters are shown to the left of each histogram: sequences shaded in black correspond to nonrepeated sequences; white boxes correspond to the 60-bp repeats; gray boxes correspond to the first eight base pairs of the 60-bp repeat; dashed boxes correspond to the mutation of the first eight base pairs to eight guanines.