Generational comparisons (F1 versus F3) of vinclozolin induced epigenetic transgenerational inheritance of sperm differential DNA methylation regions (epimutations) using MeDIP-Seq

Abstract

Environmentally induced epigenetic transgenerational inheritance of disease and phenotypic variation has been shown to involve DNA methylation alterations in the germline (e.g. sperm). These differential DNA methylation regions (DMRs) are termed epimutations and in part transmit the transgenerational phenotypes. The agricultural fungicide vinclozolin exposure of a gestating female rat has previously been shown to promote transgenerational disease and epimutations in F3 generation (great-grand-offspring) animals. The current study was designed to investigate the actions of direct fetal exposure on the F1 generation rat sperm DMRs compared to the F3 transgenerational sperm DMRs. A protocol involving methylated DNA immunoprecipitation (MeDIP) followed by next-generation sequencing (Seq) was used in the current study. Bioinformatics analysis of the MeDIP-Seq data was developed and several different variations in the bioinformatic analysis were evaluated. Observations indicate needs to be considered. Interestingly, the F1 generation DMRs were found to be fewer in number and for the most part distinct from the F3 generation epimutations. Observations suggest the direct exposure induced F1 generation sperm DMRs appear to promote in subsequent generations alterations in the germ cell developmental programming that leads to the distinct epimutations in the F3 generation. This may help explain the differences in disease and phenotypes between the direct exposure F1 generation and transgenerational F3 generation. Observations demonstrate a distinction between the direct exposure versus transgenerational epigenetic programming induced by environmental exposures and provide insights into the molecular mechanisms involved in the epigenetic transgenerational inheritance phenomenon.

Passing experiences on to future generations: endocrine disruptors and transgenerational inheritance of epimutations in brain and sperm

“…For high-dose VIN, epimutations were observed in the male F3 germline [12] and sperm [19]. To our knowledge a single report evaluated genome wide epimutations in F1 and F3 sperm due to VIN exposure [21]. Using methylated DNA immunoprecipitation followed by hybridization to a promoter microarray (MeDIP-Chip), Beck et al found that the F1 generation had fewer differentially methylated promoter regions compared to the ancestrally exposed F3 generation.…”

“…This was repeated in the F2 generation, resulting in F3 males that derived from paternal transmission of the germline. Second, we injected a much lower and realistic dosage (1 mg/kg) of VIN exposure than previous reports (50-100 mg/kg, e.g., [21]). Third, we compared outcomes of VIN, an antiandrogenic fungicide, with those of A1221, a weakly estrogenic PCB mix, to determine whether different classes of EDCs have similar or different effects.…”

“…In the same animals, we selected two brain nuclei for epimutation analysis: the central amygdala, and CA3 of the hippocampus, that are a pivotal part of the neural network underlying the anxiety and social behavioral perturbations caused by transgenerational EDC inheritance. The F1 and F3 generations were selected as our focal animals because they are best-studied [3,12,[19][20][21][22] and enabled us to put our results in the context of the published literature.…”

Defective folate metabolism causes germline epigenetic instability and distinguishesHiraas a phenotype inheritance biomarker

“…While the mechanism is unclear, this non-conventional inheritance likely occurs independent of DNA base-sequence and involves the inheritance of an epigenetic factor(s) via the germline 6,7 . Candidates in mammals include: DNA methylation, histone modifications, and/or non-coding RNA 1,2,4,[8][9][10] . How an epigenetic message resists reprogramming and is transmitted between generations remains elusive.…”

“…Few mammalian models of TEI exist and the majority focus on paternal inheritance 1,2,[8][9][10][11] .…”