Anti-adipogenic effects of 1,25-dihydroxyvitamin D3 are mediated by the maintenance of the wingless-type MMTV integration site/β-catenin pathway

1,25-dihydroxyvitamin D3 (1,25(OH)2D3), the active metabolite of vitamin D, was found to have anti-adipogenic activity, however, its mechanism of action has not been fully elucidated. In this study, 3T3-L1 preadipocytes were differentiated in the presence and absence of 1,25(OH)2D3, and the expression of the genes and proteins of the wingless-type MMTV integration site (WNT)/β-catenin pathway were analyzed. While the expression of the members of the WNT/β-catenin pathway were significantly downregulated during the adipogenesis of untreated 3T3-L1 cells, 1,25(OH)2D3 treatment was found to maintain the WNT/β-catenin pathway. Among the members of the WNT/β-catenin pathway, the levels of WNT10B and disheveled (DVL)2 as well as the phosphorylation of glycogen synthase kinase (GSK)3β were maintained by 1,25(OH)2D3 treatment. The levels of nuclear β-catenin, which were downregulated during adipogenesis, were also maintained by 1,25(OH)2D3 treatment. The results of this study suggested that the anti-adipogenic effect of 1,25(OH)2D3 was mediated by the maintenance of the WNT/β-catenin pathway, which was normally downregulated during adipogenesis.