FIGURE 1.

Thyroid hormone stimulates rPDK4 gene expression. A, HepG2 cells were transiently transfected with 2 μg of different rPDK4 luciferase reporters, 1 μg of RSV-TRβ, and 0.1 μg of TK-Renilla. Transfected cells were incubated either in serum-free Dulbecco's modified Eagle's medium or Dulbecco's modified Eagle's medium containing 100 nm T₃ for 24 h. All transfections were performed in duplicate and repeated three to six times. Luciferase and Renilla assays were performed in the same tube. Luciferase activity was corrected for both protein content and Renilla activity. Results are expressed as the relative induction by T₃ ± S.E. by comparing the T₃ induction of vectors in the treated cells to the nontreated ones. The significance is calculated relative to the shortest construct of the rPDK4-luciferase (−578/+78) (**, p value 0.001 to 0.01; ***, p value <0.001). ns, not significant. B, sequence for the region between −1256 and −973 in the rPDK4 promoter is shown with the potential TREs underlined.