title: Pulsed electromagnetic field inhibits RANKL-dependent osteoclastic differentiation in RAW264.7 cells through the Ca2+-calcineurin-NFATc1 signaling pathway.
abstract: Pulsed electromagnetic field (PEMF) has been reported to improve bone healing in osteoporosis patients. However, the precise mechanism has remained largely unknown. This study aimed to investigate the effects of PEMF on nuclear factor κB ligand (RANKL)-dependent osteoclastic differentiation and the Ca2+-calcineurin-NFATc1 signaling pathway in RAW264.7 cells in vitro. Treating RAW264.7 cells with RANKL for 4 days induced osteoclastic differentiation in vitro, and the formation of multinucleated osteoclasts, bone resorption-pit formation, tartrate-resistant acid phosphatase (TRAP) activity and the protein levels of cathepsin K, TRAP, Nuclear factor of activated T-cells, cytoplasmic 1 (NFATc1) and matrix metalloproteinase 9 (MMP-9) were significantly decreased. The mRNA levels of specific genes related to osteoclastogenesis (TRAP, NFATc1, CTSK and MMP-9) were also reduced. Moreover, the oscillations of intracellular Ca2+in RANKL-dependent RAW264.7 cells were suppressed by PEMF, as well as by inhibitors of membrane and store-operated Ca2+channels. Meanwhile, calcineurin activity was increased, although its protein level was not changed. PEMF increased phospho-NFATc1 in the cytosol while suppressing the nuclear translocation of NFATc1, thus inhibiting osteoclastic differentiation by suppressing the Ca2+-calcineurin-NFATc1 signaling pathway. Although many questions remain unresolved, to our knowledge, this is the first report demonstrating that PEMF is beneficial against RANKL-dependent osteoclastic differentiation in RAW264.7 cells in vitro via inhibiting the Ca2+-calcineurin-NFATc1 signaling pathway.
authors.affiliation: Department of Orthopaedics, Zhujiang Hospital, Southern Medical University, Guanzhou, 510280, Guangdong, People's Republic of China.
authors.forename: Jie
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Department of Orthopaedics, Zhujiang Hospital, Southern Medical University, Guanzhou, 510280, Guangdong, People's Republic of China.
authors.forename: Haixia
authors.initials: H
authors.lastname: Xu
authors.affiliation: Department of Orthopaedics, Zhujiang Hospital, Southern Medical University, Guanzhou, 510280, Guangdong, People's Republic of China.
authors.forename: Zhongyu
authors.initials: Z
authors.lastname: Han
authors.affiliation: Department of Orthopaedics, Zhujiang Hospital, Southern Medical University, Guanzhou, 510280, Guangdong, People's Republic of China.
authors.forename: Ping
authors.initials: P
authors.lastname: Chen
authors.affiliation: Department of Orthopaedics, Zhujiang Hospital, Southern Medical University, Guanzhou, 510280, Guangdong, People's Republic of China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Yu
authors.affiliation: Department of Orthopaedics, Zhujiang Hospital, Southern Medical University, Guanzhou, 510280, Guangdong, People's Republic of China.
authors.forename: Yutian
authors.initials: Y
authors.lastname: Lei
authors.affiliation: The Second Clinical Medical School, Zhujiang Hospital, Southern Medical University, Guanzhou, Guangdong, People's Republic of China.
authors.forename: Zongze
authors.initials: Z
authors.lastname: Li
authors.affiliation: Department of Pathophysiology, Key Lab for Shock and Microcirculation Research of Guangdong, Southern Medical University, Guangzhou, Guangdong, People's Republic of China.
authors.forename: Ming
authors.initials: M
authors.lastname: Zhao
authors.affiliation: Department of Orthopaedics, Zhujiang Hospital, Southern Medical University, Guanzhou, 510280, Guangdong, People's Republic of China. Electronic address: tianjing_ortho@163.com.
authors.forename: Jing
authors.initials: J
authors.lastname: Tian
mesh_terms: D000818:Animals; D019703:Calcineurin / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000502:physiology / Q000528:radiation effects; D002454:Cell Differentiation / Q000502:physiology / Q000528:radiation effects; D004574:Electromagnetic Fields; D051379:Mice; D050778:NFATC Transcription Factors / Q000378:metabolism*; D010012:Osteogenesis / Q000502:physiology* / Q000528:radiation effects; D061208:Pulsed Radiofrequency Treatment / Q000379:methods*; D053245:RANK Ligand / Q000378:metabolism*; D000067996:RAW 264.7 Cells; D011829:Radiation Dosage; D015398:Signal Transduction / Q000502:physiology / Q000528:radiation effects
chemical_list: D050778:NFATC Transcription Factors; C494005:Nfatc1 protein, mouse; D053245:RANK Ligand; C505689:Tnfsf11 protein, mouse; D019703:Calcineurin; D002118:Calcium
keywords: Ca(2+) oscillation; Calcineurin; NFATc1; Osteoclastic differentiation; PEMF