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A new specialized cell-matrix interaction in actively resorbing osteoclasts
1Bone and Mineral Centre, University College London, London WC1E 6JJ, UK. g.stenbeck@ucl.ac.uk
Journal of Cell Science
|April 6, 2000
Summary
Osteoclasts form a dynamic sealing zone that limits diffusion of bone-resorbing factors. This novel cell-matrix interaction allows simultaneous osteoclast migration and resorption.
Area of Science:
- Cell Biology
- Bone Biology
- Biochemistry
Background:
- Osteoclasts are crucial for bone resorption.
- A barrier around resorbing osteoclasts was previously hypothesized to prevent leakage.
- The precise nature and function of this barrier were unclear.
Purpose of the Study:
- To investigate the novel cell-matrix interaction in activated osteoclasts.
- To understand the mechanism of barrier formation and its role in bone resorption.
Main Methods:
- Utilized fluorescent dyes of varying molecular mass and charge.
- Employed live cell imaging to observe marker accumulation.
- Investigated the role of the actin cytoskeleton and adhesion substrate.
Main Results:
- Identified a barrier beneath resorbing osteoclasts preventing leakage of protons and proteases.
- Demonstrated rapid diffusion of negatively charged molecules (up to 10,000 M(r)) under osteoclasts within 30 seconds.
- Confirmed the involvement of the actin cytoskeleton and cell adhesion in maintaining the sealing barrier.
Conclusions:
- The osteoclast sealing zone is dynamic and allows limited diffusion, not an impermeable barrier.
- Accumulation of secreted factors is due to diffusion, not transcytosis.
- This dynamic sealing zone enables simultaneous osteoclast migration and resorption.