Figure 5.

TGF-β1 upregulates the activity of the Ig Iα1 promoter and Igα expression by increasing the Ets-1 level. (a, b) Dual luciferase reporter assays indicate that the activity of the Ig Iα1 promoter is increased by TGF-β1. After transfection with reporter plasmids for 24 h, the cells were treated with TGF-β1 (10 ng/ml) or citric acid (solvent of TGF-β1, negative control) for 24 h, and luciferase activity was assessed. At least three independent transfection experiments were performed in triplicate for each experimental construct. (c) RT-PCR showed that TGF-β1 could be synthesized by Raji, CNE1 and HeLa cells. (d–e) Western blot analysis indicates that TGF-β1 can upregulate Igα expression by increasing the Ets-1 level in a dose-dependent manner. Proteins were harvested from CNE1 cells treated with TGF-β1 for 24 h. Ig, immunoglobulin.