Mex3B inhibits DC-STAMP mRNA level and osteoclastogenesis

Bone homeostasis is maintained through continuous remodeling by osteoclast-driven bone resorption and osteoblast-mediated bone formation. Osteoclasts are multinucleated giant cells (MNCs) differentiated from myeloid progenitors of the monocytic lineage. During osteoclast maturation, DC-STAMP (dendritic cell specific transmembrane protein) has been shown as a master determinant of osteoclast cell fusion. In this study, we demonstrate that Mex3B inhibits osteoclast fusion protein DCSTAMP expression and osteoclastogenesis. During differentiation of osteoclasts, the expression of Mex3B is down-regulated by cytokines such as RANKL and TNFa, resulting in relief of Mex3B-mediated down-regulation of DC-STAMP mRNA level. Our findings not only reveal critical mechanisms on regulation of DC-STAMP-mediated osteoclastogenesis, but also point to Mex3B as a potential therapeutic target for the treatment of human bone diseases.