C/EBPα down-regulates PU.1 expression in myeloid U937 cells.

(A) U937 cells with Zn-inducible expression of C/EBPα were stimulated with 100 mM Zn for 8 hours, cDNA was synthesized, and real-time PCR was performed for PU.1. As a control, the empty vector cell line with vector pPC18 was used (right). Agarose gel was run to check for the right size band of the PCR products (data not shown). (B) C/EBPα blocks PU.1 transactivation capacity of PU.1 promoter. Transient transfection in 293T cells with a reporter construct of human PU.1 promoter and expression plasmids of PU.1 and C/EBPα. pGL2 was used as an empty vector control. Luciferase activities were measured 24 hours after transfection.