FIGURE 1.

Tissue-specific regulation of HNF1α. A and B, deletion analysis of the HNF1α promoter. Cells (3T3, βTC3, and Huh7) were transfected with various lengths of HNF1α promoter-luciferase (Luc) plasmids (1 μg) as indicated. Luciferase values are relative to the full-length constructs, which were arbitrarily set to 1.0. For the transactivation control, the shortest construct value for 3T3 and βTC3 cells was set as equal. Braces indicates the beta cell-specific cis-response element. C, luciferase activity of the mutant HNF4α-binding site HNF1α promoter. βTC3 cells were transfected with 1 μg of the indicated normal (open box) and mutant HNF4α-binding site (closed box) HNF1α promoter constructs. The luciferase value of the normal HNF1α promoter construct was arbitrarily set to 1.0. All samples were measured 24 h following transfection, and all experiments were repeated independently at least three times. ***, p < 0.001.