雌鼠全氟辛烷磺酸暴露对仔鼠DNA甲基化影响

Maternal exposure to PFOS alters DNA methylation levels in offspring rats

目的探讨大鼠出生前暴露于全氟辛烷磺酸（PFOS）对其出生后肝脏可能发生的DNA甲基化修饰程度的改变。方法在雌性SD大鼠受孕后2~21 d,给予不同剂量PFOS[0（对照）,0.1,0.6,2.0 mg/kg]灌胃染毒,子鼠出生后21 d,收集肝脏,用总甲基化检测试剂盒进行DNA总甲基化水平检测,并用亚硫酸氢钠处理后测序法（BSP）产物纯化结合质粒克隆后测序法检测LINE-1的甲基化状态,以及用AP-PCR方法评估胞嘧啶鸟嘌呤（CpG）岛的甲基化状态。结果总甲基化水平在高剂量组明显降低（P〈0.05）,均值为对照组的（90.8±4.7）%;测序显示LINE-1的甲基化水平各组间差异无统计学意义（P〉0.05）;各剂量组CpG岛甲基化水平均与对照组有明显差异（P〈0.05）;DNA甲基转移酶（DNMT）DNMT 3 a在高剂量组表达明显升高。结论总甲基化与出生前PFOS暴露水平相关,CpG岛甲基化状态也与出生前PFOS暴露水平相关。

Objective To study whether maternal exposure of perfluorooctane sulfonate（PFOS） relates with the alteration of DNA methylation level in liver of the offspring rats.Methods The pregnant rats were exposed to different doses of PFOS（control,0.1,0.6,and 2.0 mg/kg/d） during the gestational day of 2-21 by gavage.Then the rats were allowed to give birth to the offsprings and the livers of the offspring rats were collected 21 days after the birth.The total DNA methylation level,the methylation status of long interspersed repetitive element-1（LINE-1） and the methylation status of cytosine-guanosine（CpG） island were evaluated with the global DNA methylation kit,bisulfite sodium process（BSP） combined cloned sequencing,and arbitarily primed polymerase reaction（AP-PCR）,respectively.Results The global DNA methylation level at the highest dose group was significantly decreased（P0.05）.There were no significant differences in methylation levels of LINE-1 among the groups（P0.05）.The AP-PCR method showed significant difference in CpG island methylation among the three dose group compared to the control（P0.05）.In addition,the expression of DNA（cytosine-5-）-methyltransferase 3 alpha（DNMT3a） in the highest dose group was significantly increased（P0.05）.Conclusion In liver of offspring rats,the global DNA methylation level and the status of CpG island methylation are related to prenatal exposure to PFOS.