FIG. 3.

p300 activates PDX-1 dependent transcription. (A) Diagrammatic representation of PDX-1 illustrating the location of the homeodomain region (Homeo; aa 146 to 206) and conserved amino acid segments (A, 13 to 22; B, 32 to 38; C, 60 to 73) within the aa 1 to 79 activation domain (AD) (48). (B) The transcriptional activity of the wild-type and mutant GAL4:PDX-1 fusion proteins was examined in βTC-3 and HIT T-15 cells. The PDX-1 sequences within the GAL4 chimeras are noted in parentheses. Each transfection contained GAL4:PDX-1 (2.5 μg), p300 or p300 dl10 (10.0 μg), (GAL4)₅E1bCAT (2.5 μg), and pSV2 LUC (1.0 μg). The normalized fold p300 activation ± SEM is the ratio of GAL4:PDX-1 and p300 to GAL4:PDX-1 alone. (C) HIT T-15 cells were transfected with GAL4:PDX-1(1–79) or GAL4:PDX-1(1–79)ΔABC (2.5 μg), p300 or p300 dll0 (10.0 μg), and (GAL4)₅E1bCAT (2.5 μg). The extracts were assayed for both CAT and GAL4 DNA-binding activity, and the CAT activity from each GAL4:PDX-1 construct was normalized to the level of GAL:PDX-1 binding activity in the gel shift assay. The ratio of the normalized GAL4:PDX-1 activity with p300 to GAL4:PDX-1 alone from a representative experiment is shown.