模拟失重对骨形态发生蛋白2(BMP-2)诱导的ROS17/2.8细胞中ERK活性的影响

目的观察回转器模拟失重对骨形态发生蛋白2（BMP-2）诱导的大鼠骨肉瘤成骨样细胞（ROS17／2．8）中蛋白激酶ERK活性及c-fos／c-jun mRNA表达的影响。方法在地面1G和回转器模拟失重条件下培养ROS17／2．8细胞，按培养时间再分为24h和48h组，各组又分为有或无BMP-2（500ng／ml）组。提取细胞总蛋白，应用免疫沉淀和Western Blotting法检测磷酸化Elk（P-Elk）含量的变化，以反映蛋白激酶ERK的活性。提取细胞总RNA，采用反转录PCR法检测c-fos和c-jun的mRNA表达量。结果BMP-2诱导组的p-Elk表达量明显高于无BMP-2组，各时间点模拟失重组p—Elk表达量均低于1G重力对照组。模拟失重条件下24h和48h组的c-fos mRNA表达较1G对照显著降低（分别为P〈0．05，P〈0．01）。模拟失重条件下48h组的c-jun mRNA的表达显著低于1G对照水平（P〈0．01）。结论模拟失重降低了ROS17／2．8细胞中BMP-2诱导的ERK的活性，且抑制了c-fos和c-jun的基因表达。

Effects of Simulated Weightlessness on Activity of ERK Induced by BMP-2 in ROS17/2.8 Cells

Objective To investigate the effects of simulated weightlessness on activity of ERK and expression of c-fos/c-jun mRNA induced by bone morphogenetic protein-2(BMP-2) in ROS17/2.8 cells. Method ROS17/2.8 cells were cultured in 1 G condition or on a clinostat(to simulate weightlessness) rotated for 24 h and 48 h with or without BMP-2 (500 ng/ml) in the culture medium. Total protein of the cells was extracted and the expression of p-Elk was analyzed by means of immuno-precipitation and Western Blotting to examine the kinase activity of ERK. Total RNA of the cells was extracted and the expression of c-fos/c-jun mRNA was analyzed by RT-PCR. Result The content of p-Elk in the cells cultured with BMP-2 was much more than that without BMP-2 either in 1 G or in simulated weightlessness groups. The level of p-Elk in simulated weightlessness groups was much lower than that in 1 G group cultured for 24 h or 48 h. The level of BMP-2 induced expression of c-fos mRNA was significantly lower in simulated weightlessness group than that in 1G group after 24 h(P<0.05) or 48 h( P<0.01). The level of c-jun mRNA was significantly lower in 48 h simulated weightlessness group (P<0.01). Conclusion The BMP-2 can induce kinase activity of ERK and expression of c-fos/c-jun mRNA in rat osteosarcoma cells are reduced under simulated weightlessness.