The interdependent relationship between the nitric oxide signaling pathway and primary cilia in pulse electromagnetic field-stimulated osteoblastic differentiation

Author: Wen-Fang He1,2,3, Rong Qin1, Yu-Hai Gao1, Jian Zhou1, Juan-Juan Wei1, Jing Liu1, Xue-Feng Hou1, Hui-Ping Ma1, Cory J Xian4, Xue-Yan Li2, Ke-Ming Chen1,3
1 Fundamental Medical Science Research Laboratories, The 940th Hospital of Joint Logistic Support Force, People's Liberation Army of China, Lanzhou, P. R. China.
2 Department of Bioengineering, School of Life Science and Engineering, Lanzhou University of Technology, Lanzhou, P. R. China.
3 Key Laboratory of Stem Cells and Gene Drugs of Gansu Province, Lanzhou, P. R. China.
4 UniSA Clinical and Health Sciences, University of South Australia, Adelaide, South Australia, Australia.
Conference/Journal: FASEB J
Date published: 2022 Jun 1
Other: Volume ID: 36 , Issue ID: 6 , Pages: e22376 , Special Notes: doi: 10.1096/fj.202101577RR. , Word Count: 263

Pulsed electromagnetic fields (PEMFs) have long been recognized being safe and effective in treating bone fracture nonunion and osteoporosis. However, the mechanism of osteogenic action of PEMFs is still unclear. While primary cilia are reported to be a sensory organelle for PEMFs, and nitric oxide (NO) plays an indispensable role in osteogenic effect of PEMFs, the relationship between NO and primary cilia is unknown. In this study, effects of treatment with 50 Hz 0.6 mT PEMFs on osteogenic differentiation and mineralization, NO secretion, and ciliary location of specific proteins were examined in rat calvarial osteoblasts (ROBs) with normal or abrogated primary cilia. It was found that PEMFs stimulated the osteogenic differentiation by activating the NOS/NO/sGC/cGMP/PKG signaling pathway, which need the existence of primary cilia. All components of the signaling pathway including iNOS, eNOS, sGC, PKG-1, and PKG-2 were localized to primary cilia, and eNOS was phosphorylated inside the primary cilia. Besides, primary cilia were elongated significantly by PEMF treatment and changed dynamically with the activation NO/cGMP pathway. When the pathway was blocked by L-NAME, PEMFs could no longer elongate the primary cilia and stimulate the osteoblastic differentiation. Thus, this study for the first time observed activation of the NO/cGMP signaling pathway in ciliary compartment of osteoblasts, and PEMFs could not stimulate the osteoblastic differentiation if the NO signaling pathway was blocked or the ciliogenesis was inhibited. Our findings indicate the interdependent relationship between NO and primary cilia in the PEMF-promoted osteogenesis.

Keywords: endothelial nitric oxide synthase; nitric oxide; osteogenic differentiation; primary cilia; pulsed electromagnetic fields.

PMID: 35616355 DOI: 10.1096/fj.202101577RR