Quercetin Represses Apolipoprotein B Expression by Inhibiting the Transcriptional Activity of C/EBPβ
Fig 5
Quercetin represses the transcriptional activity, but not DNA-binding activity, of C/EBPβ.
(A) Caco-2 cells treated with vehicle or 100 μM quercetin for 10 h were analyzed by ChIP assays using an antibody against C/EBPβ or control IgG. Bound DNA was quantified by real-time PCR using specific primer sets for the C/EBP-RE region or distal control region. Data are presented as mean ± SD (n = 3). N.S., Not significant. (B) HEK293 cells were transfected with the reporter gene containing four copies of a yeast GAL4 upstream activation sequence (TK-MH100x4-luc) and expression plasmids for β-galactosidase and C/EBPβ fused with the yeast GAL4 DNA-binding domain (GAL4-C/EBPβ). After transfection, cells were exposed to vehicle or 100 μM quercetin for 24 h. Luciferase activities were normalized to β-galactosidase activities; a value of 1 was set in the absence of quercetin. Data are presented as mean ± SD (n = 3). **p < 0.01.