Transposable elements are regulated by context-specific patterns of chromatin marks in mouse embryonic stem cells

Area of Science:

• Genomics
• Epigenetics
• Molecular Biology

Background:

• Transposable elements (TEs) comprise a significant portion of mammalian genomes.
• While essential for biological functions, TEs pose risks to genomic stability and are epigenetically regulated.
• The complete complexity of TE epigenetic regulation remains incompletely understood.

Purpose of the Study:

• To investigate the intricate epigenetic mechanisms governing transposable element regulation in mouse embryonic stem cells.
• To identify specific epigenetic modifiers involved in controlling TE expression and chromatin accessibility.

Main Methods:

• Analysis of chromatin modifications, including H3K9me3, in mouse embryonic stem cells.
• Identification and characterization of epigenetic modifiers affecting TE expression.
• Assessment of chromatin accessibility changes upon deregulation of specific epigenetic modifiers.

Main Results:

• Transposable elements are suppressed by heterochromatic marks (e.g., H3K9me3) and exhibit complex patterns of major chromatin modifications.
• Twenty-nine epigenetic modifiers were found to significantly deregulate at least one type of TE.
• Loss of specific modifiers (Setdb1, Ncor2, Rnf2, Kat5, Prmt5, Uhrf1, Rrp8) led to widespread changes in TE expression and chromatin accessibility.
• Regulation of TEs by chromatin modifiers is context-specific, affecting distinct TE subsets.

Conclusions:

• Mammalian genomes exhibit complex epigenetic regulation of transposable elements.
• Specific epigenetic modifiers play crucial roles in controlling TE expression and maintaining genomic stability.
• Understanding these regulatory networks is vital for comprehending genome function and evolution.