地塞米松诱导成骨细胞凋亡的蛋白激酶C途径

Mechanism of osteoblast apoptosis induced by dexamethasone via the protein kinase C pathway

背景:地塞米松以增加细胞周期时间的方法提高细胞凋亡来减少成骨细胞和骨细胞的数量。蛋白激酶C是细胞内信号传导通路的一种,与细胞凋亡有关已有相关文献报道。目的:探讨地塞米松诱导成骨细胞凋亡在蛋白激酶C细胞内信号转导途径方向的机制。方法:取胎鼠骨髓间充质干细胞进行成骨诱导,分为塞米松模型组、佛波醇组和星型胞菌素组。地塞米松模型组加入1×10^-6mol/L地塞米松,佛波醇组加入1×10^-6mol/L地塞米松和1×10^-7mol/L佛波醇,星型胞菌素组加入1×10-6mol/L地塞米松和1×10^-7mol/L星型胞菌素,观察不同干预组细胞的增殖或抑制,并对细胞膜及细胞质中蛋白激酶C含量的变化进行检测。结果与结论:地塞米松可明显的诱导凋亡,加入佛波醇后凋亡明显增加,加入星形孢菌素后凋亡明显减少。加入地塞米松后胞浆的蛋白激酶C明显减少,包膜明显增加。加入地塞米松不同时间,胞浆和胞膜的蛋白激酶C变化在30 min最明显。说明地塞米松诱导成骨细胞凋亡的机制与蛋白激酶C有关,地塞米松为蛋白激酶C激动剂。细胞受到刺激后,胞浆的蛋白激酶C转移至包膜,胞浆中的蛋白激酶C量减少,包膜中的增加。

BACKGROUND： Dexamethasone can improve the cell apoptosis and decrease the number of osteoblasts and bone cells through increasing the time of cell cycle. Protein kinase C is a kind of intraecellular singnal transduction pathways, and there are related reports on the relationship between protein kinase C and cell apoptosis, 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 collected 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 x 108 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 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 cell membrane and cytoplasm was measured. RESULTS AND CONCLUSION： Dexamethasone could induce apoptosis significantly, and after added withphorbol, 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 cell membrane. At different time points after added with dexamethasone, the change of the content of protein kinase C in the cytoplasm and cell membrane 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 will moved to the cell membrane, and then the content of protein kinase C in the cytoplasm was decreased, while increased in the cell membrane.