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Mechanical loading differentially regulates membrane-bound and soluble RANKL availability in MC3T3-E1 cells.
Dae Won Kim1, Hahn-Jun Lee, Jaime A Karmin
1Center for Orthopaedic Research, Department of Orthopaedic Surgery Columbia University, 630 W. 168th Street, BB14-1411, New York, NY 10032, USA.
Annals of the New York Academy of Sciences
|July 13, 2006
Summary
Mechanical loading increases osteoblast RANKL expression. This shift towards membrane-bound RANKL may help bone cells adapt to physical stress by controlling osteoclast activity.
Area of Science:
- Biochemistry
- Cell Biology
- Bone Biology
Background:
- Receptor activator of nuclear factor kappa-B ligand (RANKL) is crucial for osteoclastogenesis.
- Mechanical loading influences bone remodeling and cellular responses in osteoblasts.
Purpose of the Study:
- To investigate the biochemical changes in RANKL expression in MC3T3-E1 cells under mechanical stress.
- To determine the effect of mechanical loading on membrane-bound versus soluble RANKL.
Main Methods:
- MC3T3-E1 cells were transfected with a murine RANKL cDNA (pEF6 HA-RANKL-V5His).
- Cells were subjected to equibiaxial mechanical stretching.
- Protein levels of endogenous and transfected RANKL were analyzed in cell lysates and conditioned media.
Main Results:
- Mechanical loading significantly increased endogenous RANKL protein expression.
- Membrane-bound RANKL (HA-RANKL-V5His) levels rose in cell lysates.
- Soluble RANKL (RANKL-V5His) levels decreased in conditioned media, potentially due to reduced TACE activity.
Conclusions:
- Osteoblasts increase membrane-bound RANKL in response to mechanical loading.
- This modulation of RANKL may be a mechanism for osteoblasts to adapt to mechanical stimuli.
- Regulation of osteoclastogenic activity by membrane-bound RANKL contributes to region-specific bone adaptation.