Atrazine induced epigenetic transgenerational inheritance of disease, lean phenotype and sperm epimutation pathology biomarkers

Abstract

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.

Adipocyte epigenetic alterations and potential therapeutic targets in transgenerationally inherited lean and obese phenotypes following ancestral exposures

“…Previous studies found an increased susceptibility to obesity in F3 generation rats ancestrally exposed to the pesticide DDT, and an increase in a lean phenotype in the F3 generation rats ancestrally exposed to the herbicide atrazine [36,37]. The present study investigated whether there were common DMR and associated genes between the control, DDT, and atrazine lineage male and female adipocytes in order to identify potential novel gene pathways modulated by DNA methylation.…”

“…No sibling or cousin breeding were used in either generation in order to avoid inbreeding depression of epigenetics or artifacts. The F3 generations were not exposed directly to DDT or atrazine in order to see transgenerational effects as previously described [36,37]. All generations of the control, atrazine, and DDT rats were given the same lighting, food, and water conditions.…”

“…The dramatic change in adipocyte area correlated to the disease with a cell area of 2040-2787 micron 2 for lean, 3638-3371 micron 2 for normal, and 4686-4294 micron 2 for obese which was independent of sex or exposure lineage. Obese and lean phenotypes were defined as an increase or decrease in adipocyte area, body mass index (BMI), and observed abdominal adiposity at dissection, as previously described [27,36,37]. The lean, obese and normal (nonobese or non-lean) animals were separated for analysis.…”

“…A recent study investigated an obesity phenotype in the F3 generation of rats following ancestral exposure to the pesticide DDT [27,36]. In contrast, a lean phenotype was observed transgenerationally following ancestral exposure to the herbicide atrazine [37]. Transgenerational epigenetic changes in the germline can promote an altered epigenome and transcriptome in embryonic stem cells, precursor cells, and eventually in all derived somatic cells [19,38,39], including adipocytes.…”

The developmental basis of disease: Update on environmental exposures and animal models

“…As reviewed in Ref. , there are data for transgenerational inheritance of diseases/dysfunctions including reproduction, obesity, psychiatric disorders from a variety of environmental stressors including vinclozolin, bisphenol A, atrazine bisphenol A plus phthalates (DEHP and DBP), permethrin plus DEET, methoxychlor, Jet fuel 8, phthalate (DEHP),dioxin, DDT, PCBs, tributyltin, nicotine, alcohol, calorie restriction, high‐fat diets, folate and stress. Mechanisms currently focus on a variety of epigenetic changes including DNA methylation, histone changes and non‐coding RNAs .…”