Figure 3.

GRE5 directs induced expression of luciferase in a dose-dependent and glucocorticoid-preferential manner. (A) Cultures transduced with vHLGREluc, vGRE(L)luc, or vGRE(S)luc were treated with indicated concentrations of dexamethasone or corticosterone and assessed for luciferase activity 2, 6, and 12 h later, respectively, at time points representing maximal induction. It should be noted that the culture media contained nM levels of glucocorticoids derived from serum; however, similar results were observed in serum-free media (data not shown). (B) Addition of dexamethasone or corticosterone resulted in significant induction relative to ethanol controls when cells were transduced with vHLGREluc, vGRE(L)luc, or vGRE(S)luc. Addition of the nonglucocorticoid steroids estradiol, progesterone (progest), and testosterone (testost) led to significant expression of luciferase above controls only in cells transduced with vGRE(L)luc. Data are percentage of the maximal average luciferase values [derived for the highest concentration for each steroid and vector (A) or for dexamethasone and each vector (B)]; statistical results obtained by Bonferroni/Dunn post hoc tests after one-way ANOVAs of each steroid and vector combination over all doses (A) or of each vector across all steroids (B). The luciferase values representing 100% were (in light units): (A) vHLGREluc/cort, 23181.0; vGRE(L)luc/cort, 1109.3; vGRE(S)luc/cort, 2159.5; vHLGREluc/dex, 43898.0; vGRE(L)luc/dex, 1886.3; vGRE(S)luc/dex, 3004.5; (B) vHLGREluc, 23529.3; vGRE(L)luc, 1556.2; vGRE(S)luc, 2339.0. Number of wells assayed were n = 3–4, vHLGREluc; n = 4, vGRE(S)luc; or n = 12, vGRE(L)luc for each dosage (A) or steroid (B). In this and subsequent figures, *, **, and *** = P < 0.05, 0.01, and 0.001, respectively, by the indicated statistical test.