Pesticide Methoxychlor Promotes the Epigenetic Transgenerational Inheritance of Adult-Onset Disease through the Female Germline

Environmental compounds including fungicides, plastics, pesticides, dioxin and hydrocarbons can promote the epigenetic transgenerational inheritance of adult-onset disease in future generation progeny following ancestral exposure during the critical period of fetal gonadal sex determination. This study examined the actions of the pesticide methoxychlor to promote the epigenetic transgenerational inheritance of adult-onset disease and associated differential DNA methylation regions (i.e. epimutations) in sperm. Gestating F0 generation female rats were transiently exposed to methoxychlor during fetal gonadal development (gestation days 8 to 14) and then adult-onset disease was evaluated in adult F1 and F3 (great-grand offspring) generation progeny for control (vehicle exposed) and methoxychlor lineage offspring. There were increases in the incidence of kidney disease, ovary disease, and obesity in the methoxychlor lineage animals. In females and males the incidence of disease increased in both the F1 and the F3 generations and the incidence of multiple disease increased in the F3 generation. There was increased disease incidence in F4 generation reverse outcross (female) offspring indicating disease transmission was primarily transmitted through the female germline. Analysis of the F3 generation sperm epigenome of the methoxychlor lineage males identified differentially DNA methylated regions (DMR) termed epimutations in a genome-wide gene promoters analysis. These epimutations were found to be methoxychlor exposure specific in comparison with other exposure specific sperm epimutation signatures. Observations indicate that the pesticide methoxychlor has the potential to promote the epigenetic transgenerational inheritance of disease and the sperm epimutations appear to provide exposure specific epigenetic biomarkers for transgenerational disease and ancestral environmental exposures.包括杀菌剂、塑料、杀虫剂、二噁英与烃类在内的环境化合物，在祖先处于胎儿性腺性别决定关键期（critical period of fetal gonadal sex determination）暴露后，可促进子代后代出现成年发病疾病（adult-onset disease）的表观遗传跨代继承（epigenetic transgenerational inheritance）。本研究探讨了杀虫剂甲氧氯（methoxychlor）在促进成年发病疾病的表观遗传跨代继承以及精子中相关差异DNA甲基化区域（differential DNA methylation regions，即表观突变（epimutations））方面的作用。研究人员在胎儿性腺发育阶段（妊娠第8至14天）对妊娠的F0代雌性大鼠进行短暂的甲氧氯暴露，随后分别对对照组（溶剂暴露组）与甲氧氯谱系后代的成年F1代及F3代（曾孙代）个体开展成年发病疾病评估。结果显示，甲氧氯谱系动物的肾病、卵巢病变与肥胖发病率均显著升高；雌雄个体的F1与F3代疾病发病率均有所上升，且F3代的多病症发病率进一步升高。F4代雌性反交（reverse outcross）后代的疾病发病率同样升高，表明疾病传播主要通过雌性生殖系（germline）完成。对甲氧氯谱系雄性个体的F3代精子表观组进行全基因组基因启动子区域分析后，鉴定出被称为表观突变的差异DNA甲基化区域（differentially DNA methylated regions, DMR）。与其他暴露特异性的精子表观突变特征相比，这些表观突变仅见于甲氧氯暴露样本。本研究结果表明，杀虫剂甲氧氯具备促进疾病表观遗传跨代继承的潜力，而精子表观突变可作为跨代疾病与祖先环境暴露的暴露特异性表观遗传生物标志物（epigenetic biomarkers）。