FIG. 6.
HES-1 modifies c-Myb function. (A) The c-Myb sites in the promoter and silencer are functionally interchangeable. Luciferase constructs containing the CD4 promoter with the c-Myb recognition site either intact (WT), mutated (MX), or substituted with the silencer c-Myb site (S2/Pro) were transfected into CD4 SP TH-clone D10 cells, and extracts from these cells were assayed for luciferase activity. Bars indicate percent of promoter activity when compared to that of the wild-type minimal CD4 promoter (100%). Data shown are compiled from at least three independent experiments with each construct. (B and C) HES-1 induces c-Myb to become a transcriptional repressor. The D10 CD4 SP TH clone was transfected with luciferase reporter constructs containing the CD4 promoter with either the c-Myb sites intact (B) or mutated (the MX mutation; panel C), a c-Myb expression vector, and increasing amounts of a HES-1 expression vector; error bars represent one standard deviation. Data are presented as fractions of the values obtained with the reporter construct and the c-Myb expression vector alone; typical values are 2 × 104 to 4 × 104 light units for the WT construct and 1 × 103 to 3 × 103 for the MX construct.