Figure 3.

The HAL2 TRE mediates transcriptional activation by T3 in frog oocytes. (a) Schematic diagram of promoter constructs pHAL2-TRE-luc (HAL2-TRE) and pHAL2-mtTRE-luc (HAL2-mtTRE) containing the wild-type and mutated HAL2 TRE, respectively. (b) The luciferase reporter construct pHAL2-TRE-luc (HAL2-TRE) or pHAL2-mtTRE-luc (HAL2-mtTRE) was coinjected with the control Renilla luciferase construct phRG-tk into the nuclei of Xenopus oocytes with or without prior cytoplasmic injection of X. laevis TRα and RXRα mRNAs. The oocytes were incubated at 18°C overnight in the presence or absence of 100 nM T3 and then used for Dual-Luciferase assays. The relative activities of the firefly luciferase to Renilla luciferase were plotted. Note that the reporter with the wild-type but not the mutated HAL2 TRE responded to T3 in the presence of TR/RXR.