Osteoporotic bone of miR-150-deficient mice: Possibly due to low serum OPG-mediated osteoclast activation

MicroRNA (miR)-150 has been shown to control B and T cell differentiation in the bone marrow. The regulation of B and T cells is directly or systematically associated with bone remodeling cells such as osteoclasts; however, the functional role of miR-150 in bone homeostasis has not been well studied. Here, we observed down-regulation of miR-150 during in vitro osteoclast differentiation and, furthermore, that miR-150 knockout mice exhibit decreased bone mass and an increased number of osteoclasts. miR-150 deficiency did not affect osteoclast differentiation, but miR150 knockout mice had significantly lower osteoprotegrin (OPG) serum levels, suggesting that the reduction of serum OPG level in miR-150 knockout mice might induce B cell expansion and subsequently increase serum levels of immunoglobulins for activating osteoclast differentiation.