人巨细胞病毒感染对人神经胶质瘤U251细胞p38MAPK表达和细胞凋亡及细胞周期的影响

目的研究人巨细胞病毒(HCMV)感染对人神经胶质瘤U251细胞p38MAPK表达水平、细胞凋亡及细胞周期的影响。方法以免疫印迹法(WesternBlotting)分析HCMV感染人神经胶质瘤U251细胞后不同时间总p38MAPK、磷酸化p38MAPK蛋白表达水平;用流式细胞仪检测HCMV感染后人神经胶质瘤U251细胞凋亡百分率变化和细胞周期的分布。结果HCMV感染后不同时间U251细胞总p38蛋白的表达水平不变,但磷酸化p38于HCMV感染后6至10h明显增高,6h、10h平均灰度值分别为186.33±7.51和188.00±7.02,与对照组比较差异有统计学意义,16h后下降至基础水平。HCMV感染能诱导U251细胞凋亡,于感染后第5天凋亡率最高,达(10.18±1.24)%,与对照组比较差异有统计学意义。HCMV感染使G1期细胞明显减少,感染后2、5、7d分别减少至(56.50±2.57)%、(62.33±2.64)%和(67.45±4.44)%,与对照组比较差异均有统计学意义,细胞周期阻滞于S期和G2期。结论HCMV感染U251细胞能够激活p38MAPK,并诱导U251细胞凋亡、细胞周期阻滞。

Effect of HCMV on p38MAPK, apoptosis and cell cycle of human glioma U251 cells

OBJECTIVE: To study the changes of p38MAPK expressions, the frequency of apoptosis and the distribution of cell cycle of hunan Glioma U251 cells after HCMV infection. METHODS: The expression of total p38 (both phosphorylated and nonphosphorylated p38) and phosphorylated p38 in U251 cells were detected by Western blotting at 15 min, 30 min, 1 h, 6 h, 10 h, 16 h, 24 h, 36 h and 48 h after HCMV infection. The apoptosis percentage and the cell cycle distribution of U251 cells at 2 d, 5 d and 7 d after HCMV infection were detected by flow cytometry (FCM). RESULTS: The results of Western blotting demonstrated that a strong increase in phosphorylated p38 was detected from 6 h to 10 h after HCMV infection, with mean gray scales 186.33 +/- 7.51 (t = 5.37, P < 0.01) and 188.00 +/- 7.02 (t = 5.26, P < 0.01 for all) at 6 h and 10 h, respectively, and p38 phosphorylation decreased to the basic level at 16 h after HCMV infection. But the overall levels of p38 protein were not significantly altered during the course of infection. FCM analysis showed that HCMV could significantly increase the apoptotic rates of U251 cells compared with controls (t = 10.84, P < 0.01), and the apoptotic percentages of the cells reached to peak [(10.18 +/- 1.24)%] at 5 d after HCMV infection. The data of FCM showed that HCMV could decrease the number of U251 cells in G1 phase and arrest the cells in S and G2 phase. The numbers of G1 phase U251 cells were significantly lowered to (56.50 +/- 2.57)% (t = 26.45, P < 0.01), (62.33 +/- 2.64)% (t = 21.20, P < 0.01) and (67.45 +/- 4.44)% (t = 10.61, P < 0.01), respectively at 2 d, 5 d and 7 d after infection. CONCLUSION: HCMV could activate p38MAPK pathway and trigger apoptosis and interfere cell cycle in U251 cells.