TABLE 2.
Maximal activation of the full-length IGFBP-1 promoter by IL-6/STAT3/AP-1 depends on HNF-1α and an intact HNF-1 binding site in HepG2 cellsa
| Promoter | Cotransfection
|
Luciferase activity
|
||
|---|---|---|---|---|
| c-Fos/c-Jun | IL-6 | Fold (avg) | SD | |
| pIBP-0.07 | − | − | 1.0 | 0.11 |
| − | + | 2.7 | 0.08 | |
| + | − | 5.1 | 0.67 | |
| pIBP-0.07 M3/HNF-1 | − | − | 0.8 | 0.08 |
| − | + | 1.0 | 0.10 | |
| + | − | 0.5 | 0.14 | |
| pIBP-0.12 | − | − | 1.0 | 0.05 |
| − | + | 4.1 | 0.30 | |
| + | − | 9.2 | 0.62 | |
| pIBP-0.12 M3/HNF-1 | − | − | 0.8 | 0.07 |
| − | + | 1.3 | 0.04 | |
| + | − | 1.0 | 0.24 | |
| pIBP-3.4 | − | − | 1.0 | 0.12 |
| − | + | 4.5 | 1.38 | |
| + | − | 4.8 | 0.25 | |
| pIBP-3.4 M3/HNF-1 | − | − | 0.5 | 0.11 |
| − | + | 0.8 | 0.27 | |
| + | − | 0.9 | 0.35 | |
| pIBP-6.6 | − | − | 1.0 | 0.10 |
| − | + | 5.3 | 0.62 | |
| + | − | 9.3 | 1.56 | |
| pIBP-6.6 M3/HNF-1 | − | − | 0.5 | 0.06 |
| − | + | 0.5 | 0.06 | |
| + | − | 0.9 | 0.14 | |
HepG2 cells were transfected with the indicated reporter constructs (25 ng) in 24-well plates. For cotransfection experiments, 25 ng of pCMV-c-fos and 25 ng of pCMV-c-jun, as indicated, were (c-Fos/c-Jun) (+) or were not (−) used. The cells were kept in medium containing 0.2% FBS for 18 h and treated (+) or not treated with rhIL-6 (100 ng/ml) for 4h. Luciferase activity was expressed as fold induction relative to the basal activity of the wild-type reporter construct in the absence of IL-6 treatment and in the absence of any indicated expression plasmids. Nine independent determinants were made for each construct by performing triplicates in three separate experiments.