[Effects of FTY720-P on EphA2-EphrinA2 bidirectional signaling in osteoclasts].

Objective: To investigate the effects of FTY720-P on EphA2-EphrinA2 bidirectional signaling in osteoclasts.

Methods: Murine RAW264.7 macrophages were induced into osteoclasts by dexamethasone and 1α, 25-dihydroxyvitamin D 3 , and identified by tartrate resistant acid phosphatase (TRAP) staining. Then, the osteoclasts were divided into 2 groups. The osteoclasts were treated with 400 ng/mL FTY720-P in experimental group and without FTY720-P in control group, respectively. After 48 hours of culture, the cells in 2 groups were detected by real-time fluorescent quantitative PCR, Western blot, and immunofluorescence staining. The expressions of EphA2, EphrinA2, RhoA, and the bone reconstruction associated proteins［bone morphogenetic protein 2 (BMP-2) and transform growth factor β 1 (TGF-β 1 )］were analyzed and compared.

Results: RAW264.7 cells were successfully induced into osteoclasts identified by TRAP staining. Compared with control group, the relative expressions of EphA2 and EphrinA2 mRNAs and proteins in experimental group significantly decreased after 48 hours ( P <0.05), and the relative expression of RhoA protein also significantly decreased ( P <0.05). The relative expressions of BMP-2 and TGF-β 1 mRNAs were significantly increased ( P <0.05), and those protein expressions were enhanced.

Conclusion: FTY720-P can down-regulate the expression of RhoA and promote the expressions of TGF- β 1 and BMP-2 by affecting the transduction of EphA2-EphrinA2 bidirectional signaling in osteoclasts.