亚慢性苯吸入小鼠凋亡相关基因Survivin、Bcl2L13的表达与甲基化状态分析

目的：探讨亚慢性苯暴露小鼠凋亡相关基因Survivin、Bcl2L13的表达与启动子甲基化状态。方法：C57BL/6J雄性小鼠亚慢性动式吸入苯，暴露浓度分别为0 ppm（对照组）、1 ppm（低浓度组）和100 ppm（高浓度组）。收集骨髓细胞，流式细胞仪检测细胞周期和细胞凋亡，实时荧光定量PCR（qPCR）检测Survivin、Bcl2L13基因的表达，基质辅助激光解吸附电离飞行时间质谱分析技术（MALDI-TOF）测定基因启动子区CpG岛甲基化水平。结果：与对照组比较，苯暴露组的细胞凋亡比例明显增大（P＜0.01），低浓度组S期细胞比例增加，高浓度组S期和G2/M期细胞的比例均显著降低。低浓度组Survivin mRNA表达下降，高浓度组Survivin、Bcl2L13 mRNA表达均显著降低。两基因启动子区CpG岛均呈低甲基化状态，其甲基化水平未受苯暴露影响。结论：亚慢性苯吸入染毒影响小鼠骨髓细胞周期，增加细胞凋亡，降低Survivin、Bcl2L13 mRNA的表达，但不影响其基因启动子的甲基化状态。

Expressions and methylation analysis of apoptosis-related genes Survivin and Bcl2L13 in mice subchronic exposure to inhaled benzene

Objective: To explore the expression level and the CpG islands methylation status of apoptosis-related genes Survivin and Bcl2L13 in mice submitted to subchronic inhalation of benzene. Methods: C57BL/6J mice were randomly divided into 3 groups: high concentration (100 ppm), low concentration (1 ppm) and control group. A subchronic benzene exposure test was carried out using the dynamic inhibition control equipment. At the end of exposure tests, bone marrow cells were collected. Cell cycle and apoptosis were detected by flow cytometry. DNA methylation status of promoter of Survivin and Bcl2L13 were determined using the Matrix-assisted Laser Desorption/Ionization-Time of Flight (MALDI-TOF) and mRNA expressions were quantitatively analyzed using real-time PCR. Results: Compared with the control group, the percentages of apoptosis cells in both exposure groups were obviously higher (P<0.01). Cell cycle arrest at S phase was observed in low concentration group. The cell percentages at S phase and G2/M phase were significantly lower in high concentration group. Survivin mRNA expression was significantly reduced in low concentration group. Both Survivin and Bcl2L13 mRNA expressions were significantly suppressed in high concentration group. The low methylation levels of CpG islands of Survivin and Bcl2L13 promoters were observed in all groups. Moreover, the methylation levels were not impacted by benzene exposure. Conclusion: Subchronic exposure to benzene induced apoptosis, change the cell cycle, and decrease the mRNA expression of apoptosis-related genes Survivin and Bcl2L13 in mice bone marrow cell; but it don’t impact the methylation status of CpG islands in promoter regions of Survivin or Bcl2L13 genes.