Department of Child and Adolescence Health, School of Public Health, Shanxi Medical University, Shanxi, Taiyuan, China.
Department of Sanitary Inspection, School of Public Health, Shanxi Medical University, Shanxi, Taiyuan, China.
PLoS One. 2018 Apr 26;13(4):e0196314. doi: 10.1371/journal.pone.0196314. eCollection 2018.
Mercury (Hg) is a well-recognized environmental pollutant known by its toxicity of development and neurotoxicity, which results in adverse health outcomes. However, the mechanisms underlying the teratogenic effects of Hg are not well understood. Imprinting genes are emerging regulators for fetal development subjecting to environmental pollutants impacts. In this study, we examined the association between preconceptional Hg exposure and the alteration of DNA methylation of imprinting genes H19, Meg3, and Peg3 in human sperm DNA.
A total of 616 men, aged from 22 to 59, were recruited from Reproductive Medicine Clinic of Maternal and Child Care Service Center and the Urologic Surgery Clinic of Shanxi Academy of Medical Sciences during April 2015 and March 2016. Demographic information was collected through questionnaires. Urine was collected and urinary Hg concentrations were measured using a fully-automatic double-channel hydride generation atomic fluorescence spectrometer. Methylation of imprinting genes H19, Meg3 and Peg3 of sperm DNA from 242 participants were examined by bisulfite pyrosequencing. Spearman's rank and multivariate regression analysis were used for correlation analysis between sperm DNA methylation status of imprinting genes and urinary Hg levels.
The median concentration of Hg for 616 participants was 9.14μg/l (IQR: 5.56-12.52 μg/l; ranging 0.16-71.35μg/l). A total of 42.7% of the participants are beyond normal level for non-occupational exposure according to the criterion of Hg poisoning (≥10 μg/L). Spearman's rank analysis indicated a negative correlation between urinary Hg concentrations and average DNA methylation levels of imprinted genes H19 (rs = -0.346, p <0.05), but there was no such a correlation for Peg3 and Meg3. Further, we analyzed the correlation between methylation level at individual CpG site of H19 and urinary Hg level. The results showed a negative correlation between urinary Hg concentrations and three out of seven CpG sites on H19 DMR, namely CpG2 (rs = -0.137, p <0.05), CpG4 (rs = -0.380, p <0.05) and CpG6 (rs = -0.228, p <0.05). After adjusting age, smoking, drinking, intake of aquatic products and education by multivariate regression analysis, the results have confirmed the correlation as mentioned above.
Mercury non-occupational environmental exposure in reproductive-aged men was associated with altered DNA methylation outcomes at imprinting gene H19 in sperm, implicating the susceptibility of the developing sperm for environmental insults.
汞（Hg）是一种众所周知的环境污染物，其毒性可导致发育和神经毒性，从而导致不良健康后果。然而，汞的致畸作用机制尚不清楚。印迹基因是受环境污染物影响的胎儿发育的新兴调节因子。在这项研究中，我们研究了孕前汞暴露与人类精子 DNA 中印迹基因 H19、Meg3 和 Peg3 的 DNA 甲基化改变之间的关系。
2015 年 4 月至 2016 年 3 月，我们从妇幼保健服务中心生殖医学诊所和山西医科大学泌尿科诊所招募了 616 名年龄在 22 至 59 岁的男性。通过问卷调查收集人口统计学信息。收集尿液并用全自动双通道氢化物发生原子荧光光谱仪测量尿汞浓度。通过亚硫酸氢盐焦磷酸测序检测 242 名参与者精子 DNA 中印迹基因 H19、Meg3 和 Peg3 的甲基化。采用 Spearman 秩相关和多变量回归分析，分析印迹基因精子 DNA 甲基化状态与尿汞水平之间的相关性。
616 名参与者的汞中位数浓度为 9.14μg/l（IQR：5.56-12.52μg/l；范围 0.16-71.35μg/l）。根据汞中毒标准（≥10μg/L），42.7%的参与者的非职业暴露超过正常值。Spearman 秩分析表明，尿汞浓度与印迹基因 H19 的平均 DNA 甲基化水平呈负相关（rs=-0.346，p<0.05），但 Peg3 和 Meg3 则没有这种相关性。进一步，我们分析了 H19 上单个 CpG 位点的甲基化水平与尿汞水平之间的相关性。结果表明，尿汞浓度与 H19 DMR 的三个 CpG 位点（CpG2(rs=-0.137，p<0.05)、CpG4(rs=-0.380，p<0.05)和 CpG6(rs=-0.228，p<0.05)）呈负相关。经多元回归分析调整年龄、吸烟、饮酒、水产摄入和教育因素后，证实了上述相关性。
在生殖期男性中，非职业性环境汞暴露与精子中印迹基因 H19 的 DNA 甲基化改变有关，提示发育中的精子易受环境因素的影响。
