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A Simple Pit Assay Protocol to Visualize and Quantify Osteoclastic Resorption In Vitro
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Osteoclasts secrete osteopontin into resorption lacunae during bone resorption
Jani Luukkonen1, Meeri Hilli2, Miho Nakamura2,3
1Department of Anatomy and Cell Biology, Cancer Research and Translational Medicine Research Unit, Faculty of Medicine, University of Oulu, P.O. Box 5000, Aapistie 5, 90014, Oulu, Finland. jani.luukkonen@oulu.fi.
Histochemistry and Cell Biology
|January 15, 2019
Summary
Osteopontin (OPN), a bone glycoprotein, is secreted by osteoclasts during bone resorption. This study confirms OPN
Area of Science:
- Bone Biology
- Glycoprotein Function
- Osteoclast Biology
Background:
- Osteopontin (OPN) is a key extracellular glycoprotein in bone.
- OPN is implicated in osteoclast attachment and bone resorption.
- The precise role of osteoclasts in OPN secretion requires further elucidation.
Purpose of the Study:
- To characterize OPN and other glycoproteins in resorption lacunae.
- To confirm osteoclast secretion of OPN.
- To investigate the role of glycan epitopes in osteoclast differentiation and function.
Main Methods:
- Electron microscopy and mass spectrometry to analyze resorption lacunae.
- Immunohistochemistry on osteoarthritic femoral heads.
- Examination of glycan epitopes and their effects on osteoclasts.
Main Results:
- Human osteoclasts secrete OPN onto bone and synthetic materials.
- OPN is present in areas of high bone turnover in osteoarthritic bone.
- α2,3- and α2,6-linked sialic acids influence osteoclast differentiation.
Conclusions:
- Osteoclasts actively secrete OPN into resorption pits.
- OPN may act as a chemokine for bone formation.
- De-sialylation of OPN impacts osteoclast differentiation, suggesting a role for sialic acids in bone remodeling.
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