Regulatory effects of 4-methoxychalcone on adipocyte differentiation through PPARγ activation and reverse effect on TNF-α in 3T3-L1 cells.

Chalcones, the biosynthetic precursors of flavonoids and isoflavonoids abundant in edible plants, possess a number of pharmacological properties, and there is growing evidence that chalcone derivatives inhibit TNF-α mediated insulin resistance. The aim of the present study was to define the effects of 4-methoxychalcone (4-MC) on adipocyte differentiation and to determine the underlying molecular mechanism. We investigated the effects of 4-MC on adipocyte differentiation and lipid accumulation, and expression of adipogenic genes in 3T3-L1 cells. Additionally, treatment with 4-MC significantly increased the PPARγ-induced transcriptional activity and 4-MC also enhanced the DNA binding affinity of PPARγ to the proliferator-activated receptor response elements (PPRE) at target promoters. Next, we tested the effect of 4-MC on the inhibition induced by TNF-α on adipocyte differentiation. Treatment with 4-MC enhanced the lipid accumulation and strongly up-regulated the expression of adipogenic markers, including PPARγ, aP2, FAS, and adiponectin during adipocyte differentiation. Finally, 4-MC attenuated the inhibitory effect of TNF-α on adipocyte differentiation and adiponectin expression and subsequently regulated the expression and secretion of various adipokines that are involved in insulin sensitivity. This study clearly demonstrates that 4-MC enhanced adipocyte differentiation, in part, by its potent effects on PPARγ activation and by its reverse effect on TNF-α.