Figure 3.

Transactivation activity of the GR fluctuates in a circadian fashion, mirroring the mRNA expression of CLOCK/BMAL1. HeLa cells were transfected with CLOCK/BMAL1 siRNAs (right panels) or control siRNA (left panels) and exposed to serum shock for 4 h. Cells were incubated with 10⁻⁶ M of dexamethasone or vehicle for 6 h before each harvest. Total RNA was purified from cells every 6 h for up to 60 h. Circles indicate mean ± se values (n=3) of fold induction of indicated mRNAs over baseline (time 0 h) in the presence (solid circles) or absence (open circles) of 10⁻⁶ M of dexamethasone. Fold induction of GILZ mRNA expression was calculated by dividing values of mRNA expression obtained in the presence of dexamethasone by those obtained in the absence of the steroid.