FIG. 6.
PCIF1 specifically inhibits PDX-1 activation of the insulin promoter. (A) HeLa cells transfected with expression vectors for Flag-PCIF1, PDX-1, E47, and the corresponding empty vectors (EV) along with the rat insulin Far-FLAT minienhancer promoter reporter 5FF1CAT. Maximal synergistic transactivation by PDX-1 and E47 was set at 100%. (B) PCIF1 does not impair E47 transactivation. HeLa cells were cotransfected with pCMX-E47 and the E47-responsive reporter (μE5+μE2+μE3)4-TATA-Luc derived from an IgH promoter element. Data are presented as the percentage of maximal E47 transactivation in the absence of cotransfected PCIF1. (C) PCIF inhibition is specific for PDX-1. Gal4-PDX-1, Gal4-E47, and Gal4-BETA2 were cotransfected with EV (solid bar) or Flag-PCIF1 (shaded bar) along with the Gal4 reporter G51bCAT. The activity of each Gal4 fusion in the absence of PCIF1 was set at 100%. All reporter activities are normalized for transfection efficiency variation according to internal-control β-galactosidase activity.