Figure 3

Functional analysis of Sp1 binding sites in the promoter of CPT1A. (A) Effect of Sp1 on activity regulation of CPT1A promoter by GBE and its flavonoids. *P < 0.05 versus respective DMSO-treated construct. D, G200, Q20, K20, I8 represent HepG2 cells incubated with 0.1% DMSO, 200 μg/ml GBE, 20 μg/ml quercetin, 20 μg/ml kaempferol, and 8 μg/ml isorhamnetin, respectively. (B) Illustration of constructs from region –50 to –5 with mutation of putative Sp1 sites. The filled circles represent each SP1. (C) Site-directed mutation analysis of Sp1 in the proximal promoter region of human CPT1A in HepG2 cells. Luciferase activity in each group was presented as a fold induction relative to untreated wild construct (value was set as 1). Each value represents mean ± SD of three individual experiments; *P < 0.05 versus each control treated group. (D) Mutation analysis of putative Sp1 binding sites in CPT1A promoter by flavonoids treatment. Values of luciferase activity were presented as a fold induction relative to the DMSO-treated pCPT1A/WT (value was set as 1). *P < 0.05 and **P < 0.01 versus respective DMSO-treated construct. Values were presented as mean ± SD of three experiments.