Identification of Sp1 as a Transcription Activator to Regulate Fibroblast Growth Factor 21 Gene Expression

Figure 2

Mutation analysis of the predicted Sp1-binding sites. (a) Nucleotide sequence encompassing the Sp1-binding sites in FGF21 gene promoter. The numbering is relative to the transcription start site. The potential Sp1-binding sites predicted by MAPPER software are underlined. (b) Luciferase reporter assay of Sp1-mutant constructs in 3T3-L1 cells. The relative promoter activity is expressed as the ratio of each construct to the pGL3-Basic. versus p(−63 to +70)Luc, versus p(−63 to +70)Luc. (c) and (d) Analysis of the influence of Sp1 on FGF21 promoter activity. 3T3-L1 cells were cotransfected with the wild-type and Sp1-mutant reporter constructs and Sp1 expression construct or Sp1 shRNA plasmid. The relative promoter activity is expressed as the ratio of each construct to the vector control pcDNA3.1 or scramble control. versus pcDNA3.1 or scramble. Sp1-binding sites are indicated with open circles. The mutations introduced into the Sp1-binding sites are represented as circles with the cross. All data represent the mean ± SD of triplicate assays in three independent experiments.

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