Sequencing DNA methylation and hydroxymethylation at co-occurring chromatin features

Area of Science:

• Epigenetics
• Genomics
• Molecular Biology

Background:

• Epigenetic modifications regulate chromatin dynamics and cell states.
• Current methods struggle to simultaneously detect multiple DNA modifications at specific chromatin features, hindering understanding of their coupled functions.

Purpose of the Study:

• To develop a method for simultaneous 6-base DNA sequencing at target chromatin features.
• To investigate the co-occurrence and coupling of DNA modifications (5mC, 5hmC) with histone marks at specific genomic locations.

Main Methods:

• Developed 6-base CUT&Tag, a novel technique for simultaneous 6-base DNA sequencing at targeted chromatin features.
• Applied 6-base CUT&Tag to profile 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) alongside histone modifications in mouse embryonic stem cells (mESCs).

Main Results:

• Identified previously unresolvable, feature-dependent 5mC/5hmC signatures using 6-base CUT&Tag.
• Demonstrated specific coupling of DNA methylation and hydroxymethylation with the H3K4me1 mark in mESC enhancers.
• Showcased that H3K4me1-derived signatures can robustly differentiate distinct enhancer functional states.

Conclusions:

• 6-base CUT&Tag provides unprecedented resolution for studying coupled DNA modifications at chromatin features.
• DNA methylation and hydroxymethylation patterns are intricately linked with specific histone marks, like H3K4me1, at enhancers.
• This method advances our understanding of how combinations of epigenetic marks regulate genome function and cell identity.