FIG. 4.

Identification of the Sp1(2) site for EAR2-, EAR3/COUP-TFI-mediated repression of the rLHR gene transcription. The wild-type (WT) or Sp1 site mutant rLHR promoter/reporter constructs [Sp1(2)X, Sp1(4)X, and Sp1(2,4)X] was cotransfected with pcDNA3.1 vector only or with expression plasmids of EAR2 (A and B) or EAR3/COUP-TFI (C and D) in CV-1 cells. The luciferase activities are expressed as a percentage of the wild-type promoter activity in the absence of the orphan receptors (100% [A and C]) or as a percentage of the repression caused by EAR2 or EAR3/COUP-TFI for the individual construct (B and D). The results were normalized by β-galactosidase activity and are expressed as means ± the SE of three independent experiments in triplicate wells.