Biochemical and Biophysical Research Communications
Emodin with PPARγ ligand-binding activity promotes adipocyte differentiation and increases glucose uptake in 3T3-Ll cells
Section snippets
Materials and methods
Reagents. Dulbecco’s modified Eagle’s medium (DMEM) was purchased from Gibco (Grand Island, NY) and fetal calf serum (FCS) was obtained from PAA laboratories (Pasching, Austria). Emodin, dexamethasone (DEX), 3-isobutyl-l-methylxanthine (IBMX), and triglyceride (TG) assay reagents were purchased from Sigma–Aldrich (St. Louis, MO); Troglitazone from Calbiochem (La Jolla, CA); Recombinant human insulin from Lily (Fegersheim, France); Trizol Reagent, SuperScript III Reverse Transcriptase and
Emodin promoted adipocyte differentiation in 3T3-L1 cells
The effects of emodin on adipogenesis were studied in 3T3-L1 preadipocytes induced to differentiate by incomplete differentiation medium. Adipocyte differentiation was confirmed by staining with Oil Red O for lipid droplet accumulation. Treatment of 3T3-L1 cells with either 25 or 50 μM emodin significantly promoted adipocyte differentiation, though it was less than that seen in response to troglitazone (Fig. 1A). OD value of Oil Red O eluted solution increased by 45% and 66% in 25 and 50 μM
Discussion
The present study provided the first data that emodin promoted the conversion of 3T3-L1 fibroblasts to adipocytes, as evidenced by increased GPDH activity and the expression of adipocyte aP2 mRNA, as well as accelerated TG accumulation, which was associated with increased mRNA expression levels of both C/EBPα and PPARγ, the key adipogenic transcription factors. By using SPR experiments, it was indicated that emodin exhibited a high binding affinity to PPARγ. However, at a higher concentration
Acknowledgments
The authors are grateful to Prof. Xu Shen, Drug Discovery and Design Center, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, for kindly helping in the measurement of binding affinity of PPARγ. This study was supported by the Shanghai-Unilever Research and Development Fund (2004) and a grant from the cultivation program of Shanghai excellence young medical talent fund (2004).
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These authors contributed equally to this work.