FIGURE 10.

PKCϵ-mediated induction of cyclin D1 transcription involves cooperation between NF-κB and CRE-interacting proteins. A, effect of transcription factor binding site mutation on induction of cyclin D1 promoter activity by PKCϵ. The binding sites for each transcription factor in the −163 bp cyclin D1 promoter construct were mutated individually. The two binding sites for Sp1 were mutated simultaneously due to the proximity of their location, and the two sites for Egr1, designated Egr1a (−118) and Egr1b (−137) were mutated individually and together. DLD1 cells were transfected with cyclin D1 promoter fragments containing the indicated mutations along with pRL-TK and treated with PMA or vehicle (EtOH) for 5 h. The activity of each cyclin D1 promoter mutant, measured by the Dual-Luciferase assay, is normalized for differences in transfection efficiency using the activity of pRL-TK in the corresponding vehicle-treated cells. Data, expressed relative to the activity of the wild-type (w.t.) promoter, are averages ± S.E. (error bars) of at least three independent experiments. *, statistically different (p < 0.05) from wild-type promoter construct. B, effect of mutating the NF-κB site and CRE on induction of cyclin D1 promoter activity by PMA in IEC-18 cells; as in A, except that IEC-18 cells were used, and PMA/vehicle treatment was for 24 h. *, statistically different (p < 0.05) from wild-type promoter construct. #, statistically different (p < 0.05) from CRE mutant promoter construct.