Fig. 3.

Overexpression of TRα induces D3 mRNA levels in GH3 cells after T₃ treatment. D1 (A) and D3 (B) mRNA levels in pituitary GH3 cells after transfection with the empty pcDNA vector (left panel) or with hTRα plasmid (right panel) and treatment with increasing doses of T₃ for 24 h (0, 1, 10, 100 nm). The experiment was repeated twice in triplicate. Data are expressed as mean ± sem. Significant differences between groups are indicated. C, T₃-TRα regulation of human DIO3 promoter activity in GH3 cells: −1486 bp of the human DIO3 promoter or pXP2-Luc empty vector and hTRα or TRβ were cotransfected into GH3 cells and analyzed for luciferase activity after T₃ treatment as described in Materials and Methods. Bars represent the mean ± sem of three different experiments, each performed in triplicate. Significant differences between groups are indicated.