Stage-Specific Modulation of Multinucleation, Fusion and Resorption by the Long Non-coding RNA DLEU1 and miR-16 in Human Primary Osteoclasts

Osteoclasts are the only cells able to resorb all the constituents of the bone matrix. While the modulation of osteoclast activity is well established for preventing bone-related diseases, there is an increasing demand for novel classes of anti-resorption agents. Herein, we investigated non-coding RNA molecules and proposed DLEU1 and miR-16 as potential candidates for modulating osteoclast functions. DLEU1 and miR-16 target cell fusion at both the early and late stages of osteoclastogenesis but operate through independent pathways. DLEU1 silencing hinders the fusion process, leading to abrogation of the phagocytic cup fusion modality and a reduction in the fusion events between mononucleated precursors and multinucleated osteoclasts, while miR-16 influences monocyte-to-osteoclast differentiation, impairing osteoclasts formation but not the number of nuclei at early stages. On the other hand, using these non-coding RNAs to engineer mature osteoclasts has implications for bone resorption. Both DLEU1 and miR-16 influence the speed of resorption in pit-forming osteoclasts, without affecting the resorbed area. However, the impact of increasing miR-16 levels extends more broadly, affecting trench-forming osteoclasts as well, leading to a reduction in their percentage, speed, and resorbed area. These findings offer potential new therapeutic targets to ameliorate bone destruction in skeletal diseases.