Retinoic acid inhibits adipogenesis via activation of Wnt signaling pathway in 3T3-L1 preadipocytes

Although retinoic acid (RA) is well known to inhibit the differentiation of 3T3-L1 cells into adipocytes both in vivo and in vitro, its molecular mechanism is not fully understood. In this report, we investigate the inhibitory mechanism of adipocyte differentiation by RA in 3T3-L1 cells. Because both RA and Wnt are known to inhibit adipogenesis at a common step involving the inhibition of PPAR-γ expression, we focused on the crosstalk between these two signaling pathways. We found that RA treatment resulted in a dramatic inhibition of adipogenesis, especially at an early phase of differentiation, and led to increased β-catenin protein expression. Moreover, RA enhances the transcriptional activity of β-catenin as well as Wnt gene expression during adipogenesis. Taken together, the present study demonstrated that Wnt/β-catenin signaling may be associated with the RA-induced suppression of adipogenesis and may cooperatively inhibit adipocyte differentiation.