FIG 3.

C-κB site is functionally associated with the Sp1III motif in HIV-1 subtype C LTR. Jurkat cells were transiently transfected with one of the reporter vectors, and 8 h following transfection the cells were exposed to TNF-α activation (100 ng/ml) or left without activation (filled black and gray bars, respectively). The luciferase secretion was evaluated from the culture supernatant at 24 h following the activation or at later times. Gene expression was significantly attenuated when the subtype C-specific C-κB site (A) or subtype C-specific Sp1 motif (B) was shifted away from their respective natural positions, when the orientation of the two motifs (middle construct) was changed, or when a 5-bp linker was inserted between the two elements (lower construct) (C). (D) The native Sp1III motif of subtype C was replaced by the heterologous Sp1 sequences from the other subtypes of HIV-1. Sequences used at motif Sp1III are depicted in Fig. 1B. Two-way analysis of variance (ANOVA) was used for statistical analysis.