Research Article

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

Figure 4

Sp1 is responsible for the upregulation of FGF21 in adipose tissues of diet-induced obese mice. (a) Real-time PCR analysis of FGF21 expression in the adipose tissue and liver of C57BL/6J mice fed with normal diet (ND) or high-fat diet (HFD). Data are means ± SEM, . versus ND-fed mice. versus ND-fed mice. (b) Western blot analysis of Sp1 protein expression in the adipose tissue and liver of C57BL/6J mice fed with ND or HFD. Quantification of the relative protein levels (expressed as the percentage of ND-fed mice protein level, arbitrarily set as 1.0) was performed by analyzing Western blot data from three independent experiments using the Scion Image program. Tubulin or actin was used as a loading control. Data are means ± SEM, . versus ND-fed mice. (c) EMSA assay. Nuclear extracts from adipose tissue of ND or HFD-induced mice were incubated with the biotin-labeled probe containing the sequence of the Sp1-B binding site. Competition experiments were performed using 100-fold unlabeled FGF21 oligonucleotide. Cross competition was performed using 100-fold excess unlabeled Sp1C oligonucleotide. The specific DNA-protein complexes and free probes are indicated by the arrow. Quantification of the relative change in protein bound (expressed as the percentage of ND-fed mice protein bound, arbitrarily set as 1.0) was performed as described in (b). versus ND-fed mice.
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