The role of microRNAs in osteoclasts and osteoporosis.

Osteoclasts are the exclusive cells of bone resorption. Abnormally activating osteoclasts can lead to low bone mineral density, which will cause osteopenia, osteoporosis, and other bone disorders. To date, the mechanism of how osteoclast precursors differentiate into mature osteoclasts remains elusive. MicroRNAs (miRNAs) are novel regulatory factors that play an important role in numerous cellular processes, including cell differentiation and apoptosis, by post-transcriptional regulation of genes. Recently, a number of studies have revealed that miRNAs participate in bone homeostasis, including osteoclastic bone resorption, which sheds light on the mechanisms underlying osteoclast differentiation. In this review, we highlight the miRNAs involved in regulating osteoclast differentiation and bone resorption, and their roles in osteoporosis.