Osteoblasts-Derived Exosomal lncRNA-MALAT1 Promotes Osteoclastogenesis by Targeting the miR-124/NFATc1 Signaling Axis in Bone Marrow-Derived Macrophages

Chenyi Zhang,1,* Lai Pan,1,* Haizheng Zhang,1 Ting Ke,1 Yuxuan Yang,1 Lan Zhang,2 Lili Chen,1 Jingyi Tan1 1Department of Periodontology, The Second Affiliated Hospital of Zhejiang University, School of Medicine, Hangzhou, People’s Republic of China; 2Stomatology Department, Zhejiang Hospital, Hangzhou, People’s Republic of China*These authors contributed equally to this workCorrespondence: Lili Chen; Jingyi Tan, Email chenlili_1030@zju.edu.cn; tanjingyi@zju.edu.cnObjective: Emerging studies have explained the crucial role of non-coding RNA (lncRNA) in various pathological progressions. The study was designed to examine the role of lncRNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) and miRNA-124 in the differentiation of osteoclasts, to provide new clues or evidences for the pathogenesis of periodontitis.Methods: We constructed an osteoblast-osteoclast Transwell co-culture system and osteoblast-derived exosomes (OB-exo) intervention model. We assessed the osteoclastogenesis as well as the level of lncRNA-MALAT1 and miRNA-124. The mechanism for lncRNA MALAT1 targeting miR-124 modulating the differentiation of osteoclasts was investigated by cell transfection, quantitative real-time reverse transcription PCR (RT-qPCR), Western blot, and Dual-Luciferase reporter assays.Results: Osteoblast-derived exosomes were isolated and identified. Co-culture and OB-exo intervention can promote osteoclastogenesis, also significantly up-regulate the expression of MALAT1, while the level of miR-124 is the opposite. Transfection of cells with small interfering RNA (si-MALAT1) and miR-124 mimic decreased the formation of TRAP+ osteoclasts and inhibited the expression of NFATc1. However, the effect was reversed when transfected with miR-124 inhibitor and si-MALAT1. The Dual-Luciferase reporter assay confirmed the binding sites between MALAT1 and miR-124, and miR-124 and NFATc1.Conclusion: LncRNA MALAT1 functioned as an endogenous sponge by competing for miR-124 binding to regulate NFATc1 expression, accelerating the progression of osteoclastogenesis.Graphical Abstract: Keywords: exosome, lncRNA, miRNA-124, osteoclast differentiation