Scoparone inhibits adipocyte differentiation through down-regulation of peroxisome proliferators-activated receptor γ in 3T3-L1 preadipocytes

This study was performed to investigate the effect of scoparone on the differentiation of 3T3-L1 preadipocytes. Scoparone inhibited triglyceride (TG) accumulation in the mature adipocytes, evidenced by Oil-red O staining and intracellular quantification. Real time-PCR analysis showed that scoparone significantly down-regulated the mRNA expression of key adipogenic transcription factors, PPARγ, C/EBPα, compared with mature adipocytes. Scoparone appeared to reduce mRNA expression of SREBP1c and FAS being related to the late stage of adipogenesis. Furthermore, aP2 and CD36/FAT, as adipocyte-specific genes, were decreased in mature adipocytes by scoparone treatment. Moreover, scoparone inhibited the up-regulated expression of PPARγ target genes by rosiglitazone to near that observed in cells treated with GW9662. The luciferase assay revealed that scoparone negatively regulates the transcriptional activity of PPARγ. Chromatin immunoprecipitation assay also showed that participation of scoparone in the regulation of PPARγ. Collectively, scoparone has a PPARγ antagonic effect and suppresses differentiation through down-regulation of adipogenic genes by PPARγ inhibition in 3T3-L1 preadipocytes.