Figure 6.

LXR agonist inhibits OPN promoter activity by negative interference with AP-1 signaling pathways. mProx24 cells were transiently transfected with a full-length OPN promoter construct. After the transfection, the cells were pretreated for 24 h with vehicle (DMSO) or the indicated concentrations of the synthetic LXR agonist T0901317 and stimulated for 24 h with high glucose (HG) medium (25 mM) as indicated. Data are expressed as the normalized luciferase activities. Data are means ± SEM. *P<0.05. (A) The transfected mProx24 cells were pretreated for 24 h with T0901317 and stimulated for 24 h with HG medium as indicated. The transfection efficiency was adjusted by normalization of the firefly luciferase activities by the Renilla luciferase activities generated by cotransfection with 10 ng pRL-CMV. (B) OPN promoter elements encoded by nucleotides −83 to −61 convey the transcriptional activity in mProx24 cells. mProx24 cells were transiently transfected with the indicated 5′-deletion constructs of the OPN promoter. The transfected mProx24 cells were left untreated (white bars) or incubated with vehicle (DMSO; black bars) or T0901317 (5 μmol/L; gray bars) for 24 h before stimulation with HG medium. (C) mProx24 cells were transiently transfected with the full-length wild-type or AP-1–mutated OPN promoter. (D) mProx24 cells were transfected with the OPN promoter construct alone or cotransfected with the OPN promoter construct and the empty pCMV vector (400 ng) or pCMV-c-Fos (200 ng) and pCMV-c-Jun (200 ng) expression vectors. (E) mProx24 cells were transfected with an AP-1–driven heterologous promoter.