Environmentally Induced Epigenetic Transgenerational Inheritance of Sperm Epimutations Promotes Genetic Mutations [MeDIP-Chip]

A variety of environmental factors have been shown to induce the epigenetic transgenerational inheritance of disease and phenotypic variation. This involves the germline transmission of epigenetic information between generations. Exposure specific sperm epimutations have been previously observed. The current study was designed to investigate the potential role genetic mutations have in the process, using copy number variations (CNV). In the first (F1) generation following exposure negligible CNV were identified, but in the transgenerational F3 generation a significant increase in CNV were identified in the sperm. The genome-wide differential DNA methylation regions (epimutations) were correlated with the genome locations of the CNV. Observations indicate the environmental induction of the epigenetic transgenerational inheritance of sperm epimutations promotes genome instability such that genetic CNV mutations are acquired in later generations. A combination of epigenetics and genetics is suggested to be involved in the transgenerational phenotypes. Sperm DNA was isolated from F1 and F3 generation rats that were ancestrally exposed to vinclozolin and dimethyl sulfoxide (vehicle) control. Equal concentrations of DNA from sperm samples from groups of three individuals were used to produce three different DNA pools per lineage. Three different comparative (CNV vs CNV) hybridization experiments were performed (2 array set) for each experiment vinclozolin versus control lineage, with each array including hybridizations from DNA pools from these different experiments. Also, two different comparative (MeDIP vs. MeDIP) hybridization experiments were performed for vinclozolin lineage versus control, with each array set encompassing DNA samples from 6 animals (3 each from vinclozolin and control). These sperm DNA samples were distinct from those used for the MeDIP-Chip analysis and those used for Copy number variation (CNV) analysis. Then, the genome-wide differential DNA methylation regions (epimutations) were correlated with the genome locations of the CNV.