- 作者: Chu-Lung Chan, Jiann-Yeu Chen, Ming-Chih Shih, Chih-Lueh Albert Wang and Ying-Ming Liou
- 作者服務機構: 1.Department of Life Sciences, National Chung-Hsing University, Taichung 40227, Taiwan 2.Research Center for Sustainable Energy and Nanotechnology, National Chung-Hsing University, Taichung, 40227, Taiwan 3.Department of Physics, National Chung-Hsing University, Taichung, 40227, Taiwan 4.Boston Biomedical Research Institute, Watertown, MA 02472, USA 5.The iEGG and Animal Biotechnology Center, and Rong Hsing Research Center for Translational Medicine, National Chung Hsing University, Taichung, 40227, Taiwan
- 中文摘要:
- 英文摘要:
Background
Osteoclasts (OCs) are motile multinucleated cells derived from differentiation and fusion of hematopoietic progenitors of the monocyte-macrophage lineage that undergo a multistep process called osteoclastogenesis. The biological function of OCs is to resorb bone matrix for controlling bone strength and integrity, which is essential for bone development. The bone resorption function is based on the remodelling of the actin cytoskeleton into an F-actin-rich structure known as the sealing zone for bone anchoring and matrix degradation. Non-muscle caldesmon (l-CaD) is known to participate in the regulation of actin cytoskeletal remodeling, but its function in osteoclastogenesis remains unclear.
Methods/results
In this study, gain and loss of the l-CaD level in RAW264.7 murine macrophages followed by RANKL induction was used as an experimental approach to examine the involvement of l-CaD in the control of cell fusion into multinucleated OCs in osteoclastogenesis. In comparison with controls, l-CaD overexpression significantly increased TRAP activity, actin ring structure and mineral substrate resorption in RANKL-induced cells. In contrast, gene silencing against l-CaD decreased the potential for RANKL-induced osteoclastogenesis and mineral substrate resorption. In addition, OC precursor cells with l-CaD overexpression and gene silencing followed by RANKL induction caused 13% increase and 24% decrease, respectively, in cell fusion index. To further understand the mechanistic action of l-CaD in the modulation of OC fusion, atomic force microscopy was used to resolve the mechanical changes of cell spreading and adhesion force in RANKL-induced cells with and without l-CaD overexpression or gene silencing.
Conclusions
l-CaD plays a key role in the regulation of actin cytoskeletal remodeling for the formation of actin ring structure at the cell periphery, which may in turn alter the mechanical property of cell-spreading and cell surface adhesion force, thereby facilitating cell-cell fusion into multinucleated OCs during osteoclastogenesis. - 中文關鍵字:
- 英文關鍵字: Osteoclastogenesis, Sealing zone, Non-muscle caldesmon (l-CaD), Cell fusion, TRAP activity, Atomic force microscopy