The link, however, between histone modifications and gene expression is not always clear. For example, Histone 3 lysine 4 trimethyaltion, a mark usually associated with transcriptionally active promoters, was enhanced in the hippocampus of adult mice exposed to alcohol during early gestation (Zhang et al., 2015). Specifically, this mark was associated with the gene Slc17a6, which encodes a protein related to vesicular glutamate transport. However, while Slc17a6 gene expression was concomitantly enhanced, downstream VGLUT2 levels were decreased, suggesting other post-transcriptional modifications, such as microRNAs (miRNAs), could be interrupting the processing of this mRNA into protein. miRNAs are an exciting branch of epigenetic research and will be discussed in relation to overlap with the developmental stress research.
