Continuous application of compressive force induces fusion of osteoclast-like RAW264.7 cells via upregulation of RANK and downregulation of LGR4

• DOI: 10.1016/j.lfs.2018.03.038
• Publication Date: 2018-03-20T15:12:38Z
• Authors: Rieko Matsuike; Hideki Tanaka; Kumiko Nakai; Mai Kanda; Maki Nagasaki; Fumiko Murakami; Chika Shibata; Kotoe Mayahara; Akira Nakajima; Natsuko Tanabe; Takayuki Kawato; Masao Maeno; Noriyoshi Shimizu
• Keywords: 0303 health sciences; NFATC Transcription Factors; Tartrate-Resistant Acid Phosphatase; RANK Ligand; Membrane Proteins; Osteoclasts; Nerve Tissue Proteins; Receptors, G-Protein-Coupled; Cell Fusion; Mice; Protein Transport; 03 medical and health sciences; RAW 264.7 Cells; Physical Stimulation; Animals; Bone Resorption

During orthodontic treatment, facilitating osteoclastic bone resorption in the alveolar bone exposed to the compressive force (CF) is an important factor for tooth movement. The present study investigated the effect of CF stimulation on the differentiation of RAW264.7 cells from precursors to mature osteoclasts.The cells were continuously stimulated with 0.3, 0.6, or 1.1 g/cm2 CF-which was generated by increasing the volume of culture medium in the wells of a 96-well plate-in the presence or absence of receptor activator of nuclear factor κB (RANK) ligand (RANKL) for 4 days.In the presence of RANKL, the number of tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells and the mRNA levels of dendritic cell-specific transmembrane protein (DC-STAMP) and osteoclast-stimulatory transmembrane protein (OC-STAMP) were increased by application of 0.6 and 1.1 g/cm2 CF as compared to 0.3 g/cm2 CF. The mRNA level of RANK was upregulated whereas that of leucine-rich repeat-containing G-protein-coupled receptor (LGR)4-another RANKL receptor was downregulated by 0.6 and 1.1 g/cm2 CF as compared to 0.3 g/cm2 CF in the absence of RANKL. The proportion of cells with nuclear translocation of the nuclear translocation of nuclear factor of activated T cells (NFAT)c1 was increased by 0.6 and 1.1 g/cm2 CF in the presence of RANKL.Continuous application of CF induced the differentiation of RAW264.7 cells into TRAP-positive multinuclear cells by enhancing the expression of DC- and OC-STAMP and the nuclear translocation of NFATc1. This may result from the CF-induced increase in RANK and decrease in LGR4 expression.