DLX3 negatively regulates osteoclastic differentiation through microRNA-124.

Homeodomain gene Distal-less-3 (DLX3) plays an essential role in the development of bones. Mutations of DLX3 are closely associated with Tricho-Dento-Osseous (TDO) syndrome featured with increased bone formation. However, the mechanism regarding whether DLX3 regulates osteoclastogenesis remains largely unknown. In this study, we firstly examined the expression of DLX3 mounting during osteoclastic differentiation process, and then established stably expressing wild type DLX3 (WT-DLX3), a novel mutant DLX3 (Q178R) found in our laboratory recently (MT-DLX3) and Dlx3 knockdown cell lines (Dlx3-shRNA) in Raw 264.7 cells using corresponding lentiviruses. Next, we investigated the influence of DLX3 on these stable cells in the process of osteoclastogenesis. The results showed that the expression of osteoclastogenesis-related genes as well as tartrate-resistant acid phosphatase-positive multinucleated cells were lower in WT-DLX3 and MT-DLX3, but higher in Dlx3-shRNA compared with control cells. Besides, the microRNA-124 expression was higher in WT-DLX3 and MT-DLX3 but lower in Dlx3-shRNA. Moreover, the microRNA-124 expression level positively correlated with DLX3, negatively with osteoclastogenesis-related gene NFATc1. Our results indicate that DLX3 negatively regulates osteoclastic differentiation through microRNA-124, which is partially responsible for the increased bone density in TDO patient. DLX3 may be exploited for osteoclastogenesis regulator and potential therapeutic target of osteoporosis in future.