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. 2012 May 16;7(5):e37012. doi: 10.1371/journal.pone.0037012

Figure 6. Sp1 expression levels had an impact on modulation of LEDGF/p75 promoter activity.

Figure 6

A, Interrupting Sp1 activity by artemisinin interrupted LEDGF/p75 promoter activity in a concentration-dependent manner. Upper panel, a diagram of the LEDGF/p75 promoter representing three Sp1-binding sites (−170/+35) used for CAT activity. A selective Sp1 inhibitor [33], artemisinin, reduced the activity of LEDGF/p75 promoter in LECs in dose-dependent fashion. Artemisinin or its diluents (control) were added to culture medium of LEDGF/p75 promoter constructs or empty vector transfected cells monolayer. Cells were disrupted and CAT activities were measured as described in the Materials and Methods section. Data are the mean of three experiments, and error bars indicate standard deviation (**p<0.001). B and C, Influence of Sp1 overexpression on transcriptional activity of LEDGF/p75 promoter. Plasmid encoding pCAT-LEDGF/p75 (−170/+35) or pCAT-V was cotransfected into hLECs (B) and Cos7 cells (C) with indicated amounts of pCMV-Sp1. Following CAT assay, CAT values were analyzed and represented as histograms, with Sp1 (black bar) or without Sp1 (open bar) overexpression. Empty CAT vector shows insignificant CAT activity (gray bar). Transfections were carried out as described in Materials and Methods and level of Sp1 protein was evaluated using Western analysis (B and C, Upper panel). The data are representative of at least three independent experiments. Each value represents the mean ± S.D. (**p<0.001).