Alterations in sperm small RNA expression mediate Vinclozolin induced epigenetic transgenerational inheritance of disease

Epigenetic transgenerational inheritance of disease and phenotypic variation can be induced by several toxicants such as vinclozolin. This phenomenon can involve DNA methylation, ncRNA and histone methylation and/or acetylation in the germline (e.g. sperm). These different epigenetic marks are called epimutations and can transmit in part the transgenerational phenotypes. The current study was designed to investigate the vinclozolin induced concurrent alterations of a number of different epigenetic processes including DNA methylation, non-coding RNA (ncRNA) and histone retention in sperm. Gestating females were exposed transiently to vinclozolin during fetal gonadal development. The directly exposed F1 generation, the directly exposed germline F2 generation and the transgenerational F3 generation sperm were studied. DNA methylation and ncRNA were altered in each generation sperm with the direct exposure F1 and F2 generations being distinct from the F3 generation epimutations. The long ncRNA and piRNA were the most highly altered classes of ncRNAs. A very conserved set of histone retention sites were found in the control and vinclozolin lineage F1, F2 and F3 generations. Interestingly, an increased number of histone retention sites were found only in the F3 generation vinclozolin sperm. All three different epimutation types were affected in the vinclozolin lineage transgenerational sperm (F3 generation). The direct exposure generations (F1 and F2) epigenetic alterations were distinct from the transgenerational sperm epimutations. The genomic features and gene pathways associated with the epimutations were investigated to help elucidate the integration of these different epigenetic processes. Our results show that the three different types of epimutations are involved and integrated in the mediation of the epigenetic transgenerational inheritance phenomenon.