Abstracts are provided in the language submitted.

Transposable elements (TEs) are DNA elements able to copy themselves within the genome. This ability has led to interest in their potential as regulatory elements that spread within the human genome throughout evolution. Despite minimal TEs expression due to silencing, TEs still manage to have a noticeable impact on host genome in numerous contexts. For instance, some TEs have been shown to behave like cis-regulatory elements, enhancers and some were co-opted by the host genome. We believe that we can get a better understanding of the genome regulation linked to transposable elements through the epigenome. Here, we leverage a comprehensive dataset of 3558 histone mark ChIP-seq samples across tissues from the International Human Epigenome Consortium (IHEC) and examine the relationship between TEs, the epigenome and cell types. We show that TEs have drastically different enrichments levels in different histone marks and that the enrichment further varies between cell types. We find that TEs are generally depleted but that L1 are enriched almost exclusively near H3k9me3 histone marks, while MIRs were enriched in H3K4me1, H3K27ac and H3K27me3 and Alus were enriched in H3K36me3. Furthermore, we find that TE enrichment can be cell type specific in certain contexts and that they are found in regions associated with relevant functions. These results further support the importance of transposable elements by providing a comprehensive profile of TEs across cell types and histone marks.

Jeffrey Hyacinthe