Transposable elements impact the human regulatory landscape through cell type specific epigenomic associations

Area of Science:

• Genomics
• Epigenetics
• Molecular Biology

Background:

• Transposable elements (TEs) are mobile DNA sequences with significant roles in genome evolution.
• TEs can function as cis-regulatory elements and are integrated into the human genome.
• The relationship between TEs and the epigenome, specifically histone marks, is not systematically analyzed across diverse human cell types.

Purpose of the Study:

• To systematically analyze the association between transposable elements and chromatin histone marks across various human cell types.
• To identify specific patterns of TE enrichment or depletion in relation to different histone modifications.
• To explore the functional implications of cell-type specific TE-histone mark interactions.

Main Methods:

• Utilized a large dataset from the International Human Epigenome Consortium (IHEC).
• Analyzed 4867 uniformly processed ChIP-seq experiments for 6 key histone marks.
• Examined TE enrichment levels across 47 distinct human cell types.

Main Results:

• Transposable elements exhibit significantly different enrichment levels across various histone marks.
• TEs are generally depleted, but specific elements like LINE-1 (L1s) show enrichment in the H3K9me3 histone mark.
• Identified 456 cell type-histone-TE combinations with strong, cell-type specific enrichments, many linked to biological processes.

Conclusions:

• The epigenome plays a crucial role in modulating the impact of transposable elements in the human genome.
• Specific histone marks and cell types show distinct associations with transposable elements.
• These findings highlight cell-type specific regulatory roles for transposable elements mediated by epigenetic modifications.