FIGURE 4.

C/EBPβ activates Tudor-SN gene expression. A, the Tudor-SN promoter region contains a C/EBPβ binding site as indicated (highlighted box) in rat, mouse, and human. B, C/EBPβ enhances the gene transcriptional activity of Tudor-SN. 3T3-L1 cells were co-transfected with pGL3-PL-Luc reporter gene constructs carrying the Tudor-SN promoter region (0.5 μg) and β-galactosidase vector (0.5 μg) with different amounts of the C/EBPβ expression plasmid. Normalized luciferase activity is presented. The mean normalized luciferase values of three independent experiments with S.D. are shown. C, chromatin immunoprecipitation (IP) assays of the association of C/EBPβ with the Tudor-SN promoter in 3T3-L1 cells. Cross-linked chromatin from 3T3-L1 cells was incubated with antibodies against C/EBPβ or lgG antibody as a negative control. The immunoprecipitates were analyzed by PCR with primers specific for the mouse Tudor-SN promoter at different time points and primers amplifying a region outside the C/EBPβ binding sites (lower panel) as a negative control. The Input represents the PCR product of total chromatin DNA detection.