Downregulation of runx2 by 1, 25-dihydroxyvitamin D3 induces the transdifferentiation of osteoblasts to adipocytes

Abstract

1, 25-Dihydroxyvitamin D3 (1, 25(OH)2D3) indirectly stimulates bone formation, but little is known about its direct effect on bone formation. In this study, we observed that 1, 25(OH)2D3 enhances adipocyte differentiation, but inhibits osteoblast differentiation during osteogenesis. The positive role of 1, 25(OH)2D3 in adipocyte differentiation was confirmed whenmurine osteoblasts were cultured in adipogenic medium. Additionally, 1, 25(OH)2D3 enhanced the expression of adipocyte marker genes, but inhibited the expression of osteoblast marker genes in osteoblasts. The inhibition of osteoblast differentiation and promotion of adipocyte differentiation mediated by 1, 25(OH)2D3 were compensated by Runx2 overexpression. Our results suggest that 1, 25(OH)2D3 induces the transdifferentiation of osteoblasts to adipocytes via Runx2 downregulation in osteoblasts.