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Communication between ephrinB2 and EphB4 within the osteoblast lineage
T J Martin1, E H Allan, P W M Ho
1Department of Medicine, St Vincent's Institute and University of Melbourne, Melbourne, Fitzroy, 3065, Australia. jmartin@svi.edu.au
Advances in Experimental Medicine and Biology
|December 2, 2009
Summary
EphrinB2/EphB4 signaling in osteoblasts regulates bone formation. Blocking this pathway inhibits osteoblast differentiation and gene expression, suggesting a key role in bone remodeling.
Area of Science:
- Cell Biology
- Bone Biology
- Developmental Biology
Background:
- Ephrin and Eph family proteins mediate cell-cell interactions.
- EphrinB2 and its receptor EphB4 are involved in bone remodeling.
- Parathyroid hormone (PTH) and PTH-related peptide (PTHrP) influence osteoblast function.
Purpose of the Study:
- To investigate the role of ephrinB2/EphB4 signaling in osteoblast differentiation.
- To determine the effect of blocking ephrinB2/EphB4 interaction on osteoblast gene expression and mineralization.
Main Methods:
- Treatment of osteoblasts with PTH and PTHrP to increase ephrinB2 expression.
- Inhibition of ephrinB2/EphB4 signaling using a synthetic peptide antagonist and recombinant soluble EphB4 (sEphB4).
- Analysis of osteoblast gene expression and mineralization.
Main Results:
- PTH and PTHrP increased ephrinB2 mRNA and protein in osteoblasts.
- Inhibition of ephrinB2/EphB4 signaling reduced osteoblast mineralization.
- Blocking the pathway decreased the expression of late osteoblast differentiation genes.
Conclusions:
- EphrinB2/EphB4 signaling plays a paracrine role in osteoblast differentiation.
- This signaling pathway contributes to the regulation of bone formation at remodeling sites.
- Osteoclast-derived ephrinB2 may couple bone resorption to formation.
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