FIG. 1.

Full basal expression of the GnRHR requires the −298 ATTA site. A, Sites in the GnRHR proximal 5′-flanking region important for transcriptional regulation are shown. Gray ovals represent the four ATTA sites. Numbers above the promoter indicate the location of each regulatory element relative to the transcriptional start site. Nucleotides in bold and underlined indicate bases changed to cggc in subsequent transfection and EMSA experiments. B, Basal expression of luciferase reporter plasmids containing either the WT 1.2-kb region of the mouse GnRHR promoter (white bar, WT) or the indicated mutation (black bars, −360, −298, −278, −253, and the quadruple ATTA mutant, MX4) were assayed by transient transfections in αT3-1 cells. Data are the means ± sem of at least three independent experiments, each performed in triplicate, and were normalized as described in Materials and Methods. A one-way ANOVA followed by the Tukey-Kramer HSD post hoc test was used. *, Values that differ significantly from WT GnRHR (P ≤ 0.05).