Fig. 2. Identification of two active cis-regulatory elements and corresponding transcription factors on the CP27 proximal promoter: NF-Y binds to the CCAAT-box and USF1 binds to an E-box.
A and B, electrophoretic mobility shift analysis. Nuclear extracts from ES cells were incubated with 32P-labeled oligonucleotide probes CP−93/−56 (A) or CP−55/−27 (B) in the presence of various competitors, mutants and antibodies. The labels above individual lanes read NE = nuclear extract, AB = antibody. C, chromatin immunoprecipitation. NF-YA (lane 2) or USF1 associated DNA fragments (lane 3) were immunoprecipitated using anti-NF-YA or USF1 antibodies. Flag antibody served as negative control. D, transient transfection experiments. The plasmid pGL−93/+48 CCAATm is a modified construct of pGL−93/+48 in which the CCAAT-box had been mutated; the plasmid pGL−55/+48 Em is a mutated construct of pGL−55/+48 in which the E box was modified. The asterisks in Fig. D indicate significant differences (P < 0.05).