Mechanism of osteoblast apoptosis induced by dexamethasone via the protein kinase C pathway / 中国组织工程研究

ABSTRACT

BACKGROUND:Dexamethasone can improve the cellapoptosis and decrease the number of osteoblasts and bone cells through increasing the time of cellcycle. Protein kinase C is a kind of intraecellular singnal transduction pathways, and there are related reports on the relationship between protein kinase C and cellapoptosis. OBJECTIVE:To investigate the mechanism of dexamethasone-induced osteoblast apoptosis via protein kinase C intracellular signal transduction pathway. METHODS:Fetal rat bone marrow mesenchymal stem cells were col ected for osteogenic induction, and the cells were divided into dexamethasone group, phorbol group and star cytochalasin group. The cells in the dexamethasone group were added with 1×10-6 mol/L dexamethasone, the cells in the phorbol group were added with 1×10-6 mol/L dexamethasone and 1×10-7 mol/L phorbol, while the cells in the star cytochalasin group were added with 1×10-6 mol/L dexamethasone and 1×10-7 RESULTS AND CONCLUSION:Dexamethasone could induce apoptosis significantly, and after added with mol/L star cytochalasin. The proliferation and inhibition of the cells in different intervention groups were observed, and the content of protein kinase C in the cellmembrane and cytoplasm was measured. phorbol, the apoptosis was increased significantly;while after added with star cytochalasin, the apoptosis was decreased significantly. After added with dexamethasone, the content of protein kinase C in the cytoplasm was significantly decreased, while increased in the cellmembrane. At different time points after added with dexamethasone, the change of the content of protein kinase C in the cytoplasm and cellmembrane was most significant at 30 minutes. The results indicated that mechanism of dexamethasone-induced osteoblast apoptosis was correlated with protein kinase C, and dexamethasone was the agonist of protein kinase C. After the cells were stimulated, the protein kinase C in the cytoplasm wil moved to the cellmembrane, and then the content of protein kinase C in the cytoplasm was decreased, while increased in the cellmembrane.