Involvement of receptor-interacting protein 140 in estrogen-mediated osteoclasts differentiation, apoptosis, and bone resorption.

Estrogen withdrawal following menopause results in an increase of osteoclasts formation and bone resorption, which is one of the most important mechanisms of postmenopausal osteoporosis. Recently, growing evidence has suggested that receptor-interacting protein 140 was implicated in estrogen-regulated metabolic disease, including fat metabolism and lipid metabolism. However, little is known regarding the role of receptor-interacting protein 140 in the regulation of bone metabolic by estrogen. In the present study, Western blotting disclosed that estrogen brings a significant increasing expression of receptor-interacting protein 140 in osteoclasts, but not in osteoblasts and bone marrow mesenchymal stem cells. Furthermore, analysis of TRAP staining and bone resorption assay showed that depletion of receptor-interacting protein 140 could significantly alleviate the inhibitory effects of estrogen on osteoclasts formation and bone resorption activity. Moreover, estrogen could induce osteoclasts apoptosis by increasing receptor-interacting protein 140 expression through the Fas/FasL pathway. Taken together, receptor-interacting protein 140 might be a critical player in estrogen-mediated osteoclastogenesis and bone resorption.