Figure 6.

The transcription factor E2F1 upregulates Stau2 transcription. (A) E2F1 is fused to the estrogen receptor-binding domain tagged with HA (HA-ER). The ER-fusion protein is expressed in the cytosol and translocates to the nucleus in the presence of the ER ligand 4-hydroxytamoxifen (OHT). HCT116 cells were transfected with plasmids coding for HA-ER or HA-ER-E2F1 and incubated in the presence (+) or absence (−) of OHT (500 nM). Expression of the proteins was detected by western blotting. *: non-specific bands. (B) Expression of known (APAF1) and putative (Stau2) endogenous targets of E2F1 was analyzed by RT-qPCR and normalized on that of GAPDH mRNA. Expression in the absence of OHT and E2F1 (ER-OHT) was arbitrarily normalized to 1. Data represent the means and standard deviation of three independently performed experiments. (C) HA-ER- and HA-ER-E2F1-expressing HCT116 cells were co-transfected with plasmids coding for YFP and F-luc under the control of the minimal Stau2 promoter (pGL3 Stau2 -394) or without any promoter region (pGL3 control). Cells were then incubated in the absence or presence of OHT. A ratio of F-luc activity on YFP signal was calculated in each condition. The ratio in the absence of OHT was arbitrary fixed to 1. Data represent the means and standard deviation of three independently performed experiments. Statistical analyses (Student's t-test) are indicated when significant. **P-value ≤ 0.01.