Sakuranetin induces adipogenesis of 3T3-L1 cells through enhanced expression of PPARγ2

Takeshi Saito, Daigo Abe, Keizo Sekiya, Takeshi Saito, Daigo Abe, Keizo Sekiya

Index: Biochem. Biophys. Res. Commun. 372(4) , 835-9, (2008)

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Abstract

Sakuranetin (5,4′-dihydroxy-7-methoxyflavone) belongs to the flavanone class of polyphenols predominantly known as phytoalexin in rice plant. In this study, we demonstrate that sakuranetin strongly induces differentiation of 3T3-L1 preadipocytes, as evidenced by increased triglyceride accumulation and glycerol-3-phosphate dehydrogenase (GPDH) activity. In addition, even in the absence of adipogenic hormonal stimuli, sakuranetin strongly induced adipogenesis and expression of genes that are critical for the adipocytes phenotype. Time-course analyses indicated that sakuranetin induces PPARγ2 expression without prior induction of C/EBPβ, a transcriptional regulator of PPARγ2 in adipogenesis. In 3T3-L1 preadipocytes, the transcriptional factors GATA-2 and GATA-3 are known to down-regulate adipogenesis by direct binding to the C/EBPβ protein and to the GATA-binding site on the PPARγ2 promoter. We found that sakuranetin significantly reduced the expression of GATA-2. Moreover, we observed that sakuranetin stimulated glucose uptake in differentiated 3T3-L1 adipocytes. These results suggest that sakuranetin may contribute to maintain glucose homeostasis in animals.