Expression of EPH-EPHRIN signalling in osteocytes under mechanical loading

Abstract

AIMS: To investigate the effect of mechanical loading on ephrinB2-EphB4 and ephrinA2-EphA2 signalling pathways in the osteocyte-like MLO-Y4 cell line. MATERIALS AND METHOD: MLO-Y4 cells were seeded on collagen-coated plates and loaded with a force of 2000 μ strain for 1 hour, while the cells treated with no force loading served as the control. The cells were collected and analysed by real-time polymerase chain reaction to assess the expression of EphB4, ephrinB2, EphA2, and ephrinA2. All data were expressed as the mean standard deviations from three independent experiments. t-tests were used for two-sample comparisons. Significant differences were indicated as P < 0.05. RESULTS: Both ephrinB2-EphB4 and ephrinA2-EphA2 signalling pathways were altered by mechanical stress stimulation. The mRNA expression level of EphB4 in osteocytes was significantly increased after 1 hour of mechanical loading (P < 0.05), and ephrinA2 was also up-regulated under mechanical stress stimulation (P < 0.05). CONCLUSION: Mechanical stress alters Eph-ephrin signalling in osteocytes, with both ephrinB2-EphB4 and ephrinA2-EphA2 signalling pathways regulated, which indicates a dynamic balance between bone formation and bone resorption.