TR4 Inhibits LXR-mediated Decrease of Lipid Accumulation in 3T3-L1 Adipocytes

TR4 has been suggested to play an important role in lipid metabolism in adipocytes. Although TR4 facilitates lipid accumulation during adipogenesis, the regulatory effect of TR4 on lipid storage in mature adipocytes remains unclear. We showed that TR4 inhibited the LXR agonist GW3965-mediated decrease of lipid accumulation in 3T3-L1 adipocytes. A reporter gene analysis revealed that TR4 suppressed LXRα transcriptional activity, although LXRα was unable to affect TR4 transcriptional activity. Moreover, adding TR4 resulted in reduced LXRα binding to the LXR responsive element in a gel shift assay. Additionally, the suppressive effect of GW3965 on perilipin expression and lipid accumulation in 3T3-L1 adipocytes was abolished by TR4 overexpression. Taken together, our data demonstrate that TR4 plays an inhibitory role in LXRα-mediated suppression of lipid accumulation in 3T3-L1 adipocytes. This TR4 protective effect is mediated, in part, by blocking the suppressive effect of GW3965 on perilipin gene expression.