McBirney Margaux, King Stephanie E, Pappalardo Michelle, Houser Elizabeth, Unkefer Margaret, Nilsson Eric, Sadler-Riggleman Ingrid, Beck Daniel, Winchester Paul, Skinner Michael K
Center for Reproductive Biology, School of Biological Sciences, Washington State University, Pullman, Washington, United States of America.
Indiana University, School of Medicine, Department of Pediatrics, Indianapolis, Indiana, United States of America.
PLoS One. 2017 Sep 20;12(9):e0184306. doi: 10.1371/journal.pone.0184306. eCollection 2017.
Ancestral environmental exposures to a variety of environmental toxicants and other factors have been shown to promote the epigenetic transgenerational inheritance of adult onset disease. The current study examined the potential transgenerational actions of the herbicide atrazine. Atrazine is one of the most commonly used herbicides in the agricultural industry, in particular with corn and soy crops. Outbred gestating female rats were transiently exposed to a vehicle control or atrazine. The F1 generation offspring were bred to generate the F2 generation and then the F2 generation bred to generate the F3 generation. The F1, F2 and F3 generation control and atrazine lineage rats were aged and various pathologies investigated. The male sperm were collected to investigate DNA methylation differences between the control and atrazine lineage sperm. The F1 generation offspring (directly exposed as a fetus) did not develop disease, but weighed less compared to controls. The F2 generation (grand-offspring) was found to have increased frequency of testis disease and mammary tumors in males and females, early onset puberty in males, and decreased body weight in females compared to controls. The transgenerational F3 generation rats were found to have increased frequency of testis disease, early onset puberty in females, behavioral alterations (motor hyperactivity) and a lean phenotype in males and females. The frequency of multiple diseases was significantly higher in the transgenerational F3 generation atrazine lineage males and females. The transgenerational transmission of disease requires germline (egg or sperm) epigenetic alterations. The sperm differential DNA methylation regions (DMRs), termed epimutations, induced by atrazine were identified in the F1, F2 and F3 generations. Gene associations with the DMRs were identified. For the transgenerational F3 generation sperm, unique sets of DMRs (epimutations) were found to be associated with the lean phenotype or testis disease. These DMRs provide potential biomarkers for transgenerational disease. The etiology of disease appears to be in part due to environmentally induced epigenetic transgenerational inheritance, and epigenetic biomarkers may facilitate the diagnosis of the ancestral exposure and disease susceptibility. Observations indicate that although atrazine does not promote disease in the directly exposed F1 generation, it does have the capacity to promote the epigenetic transgenerational inheritance of disease.
祖先暴露于各种环境毒物和其他因素已被证明会促进成年期疾病的表观遗传跨代遗传。当前的研究检测了除草剂阿特拉津潜在的跨代作用。阿特拉津是农业行业中最常用的除草剂之一，尤其用于玉米和大豆作物。远交系妊娠雌性大鼠被短暂暴露于载体对照或阿特拉津。F1代后代进行繁殖产生F2代，然后F2代繁殖产生F3代。对F1、F2和F3代对照和阿特拉津谱系大鼠进行衰老并调查各种病理情况。收集雄性精子以研究对照和阿特拉津谱系精子之间的DNA甲基化差异。F1代后代（在胎儿期直接暴露）未患疾病，但与对照相比体重较轻。发现F2代（孙代）与对照相比，雄性和雌性睾丸疾病和乳腺肿瘤的发生率增加，雄性青春期提前，雌性体重下降。发现跨代F3代大鼠睾丸疾病发生率增加，雌性青春期提前，行为改变（运动多动），雄性和雌性均表现为瘦型表型。跨代F3代阿特拉津谱系雄性和雌性中多种疾病的发生率显著更高。疾病的跨代传播需要种系（卵子或精子）表观遗传改变。在F1、F2和F3代中鉴定出由阿特拉津诱导的精子差异DNA甲基化区域（DMRs），即表观突变。鉴定了与DMRs相关的基因。对于跨代F3代精子，发现独特的DMRs（表观突变）集与瘦型表型或睾丸疾病相关。这些DMRs为跨代疾病提供了潜在的生物标志物。疾病的病因似乎部分归因于环境诱导的表观遗传跨代遗传，表观遗传生物标志物可能有助于诊断祖先暴露和疾病易感性。观察结果表明，尽管阿特拉津不会在直接暴露的F1代中促进疾病，但它确实有能力促进疾病的表观遗传跨代遗传。
