FIG. 6.

Cotransfection of NFI and TTF-1 with the coactivator protein p300 caused synergistic activation of the 0.32 SP-C promoter. JEG cells were cotransfected with 1.5 μg of the SP-C luciferase construct indicated at the left and combinations of expression vectors for NFI-A1 (1 μg), TTF-1 (0.5 μg), and p300 (0.5 μg), with pCMVβgal (0.5 μg) to control for transfection efficiency. The relative activity of each luciferase construct cotransfected with the relevant empty vector was set to 1 and data were plotted as means ± SE (n = 9). Schematic representations of the transcription factor interactions with each construct are shown at the left, and mutant sites are indicated by an “X.” All NFI sites are mutated in pSPC-NFI(−) and both TTF-1 sites are mutated in the C2 footprinted region of pSPC-TTF-1(−).