Melatonin Attenuates RANKL-Induced Osteoclastogenesis via Inhibition of Atp6v0d2 and DC-STAMP through MAPK and NFATc1 Signaling Pathways

Seong-Sik Kim,In-Ryoung Kim,Bong-Soo Park,Soon-Pill Jeong

doi:10.3390/molecules27020501

Abstract

Melatonin is a hormone secreted by the pineal gland that is involved in the biorhythm of reproductive activities. The present study investigated the inhibitory effects of melatonin on osteoclastogenesis in RAW 264.7 cells according to changes in V-ATPase and the corresponding inhibition of the MAPK and NFATc1 signaling processes. Methods: the cytotoxic effect of melatonin was investigated by MTT assay. Osteoclast differentiation and gene expression of osteoclast-related factors were confirmed via TRAP staining, pit formation assay, immunofluorescence imaging, western blot, and real-time PCR. Results: melatonin was found to inactivate the p38 and JNK of MAP kinase in RAW264.7 cells treated with RANKL and treated with a combination RANKL and melatonin for 1, 3, and 5 days. The melatonin treatment group showed a reduction in osteoclastogenesis transcription factors and ATP6v0d2 gene expression. Conclusions: melatonin inhibits osteoclast differentiation and cell fusion by inhibiting the expression of Atp6v0d2 through the inactivation of MAPK and NFATc1 signaling in RANKL-stimulated RAW264.7 macrophages. The findings of the present study suggest that melatonin could be a suitable therapy for bone loss and imply a potential role of melatonin in bone health.

Highlights

Accepted: 12 January 2022Melatonin is a small indole molecule synthesized from serotonin in the pineal gland [1,2]
MTT assays were performed to observe whether the cell viability of melatonin affected RAW 264.7 macrophages
Melatonin (0, 100, 200, 300, 400, and 500 μM), which did not exhibit cytotoxicity, was applied to RAW264.7 cells to observe the inhibitory effect on RANKL-induced osteoclastogenesis

Summary

Introduction

Melatonin is a small indole molecule synthesized from serotonin in the pineal gland [1,2]. It is involved in a variety of physiological processes, including biorhythms, reproduction, aging, and the cardiovascular and immune systems. In vitro and in vivo studies provide evidence that melatonin treatment contributes to the prevention of bone loss [6]. It regulates the balance of osteoclasts and osteoblasts through signaling transduction, including the Wnt, NFκB, and MAPK pathways, to improve bone quality [7,8,9]. Melatonin intake may be an alternative therapy for improving bone health [10]

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Results

Conclusion