MAE-seq refines regulatory elements across the genome

Area of Science:

• Genomics and Molecular Biology
• Epigenetics and Gene Regulation

Background:

• Precise cell fate determination requires accurate identification of regulatory elements (REs) and their interactions with genes.
• Current methods for defining REs lack resolution, leading to sequence redundancy and ambiguity in genomic context.

Purpose of the Study:

• To develop and validate a high-resolution method for experimentally identifying functional REs at a 25-bp scale.
• To characterize novel enhancers and their roles in gene regulation across different cell types.

Main Methods:

• MAE-seq (Massive Active Enhancers by Sequencing) was developed to identify functional REs at 25-bp resolution.
• MAE-seq was applied to mouse embryonic stem cells (mESCs), C2C12, and HEK 293T cells, analyzing trillions of DNA fragments and billions of cells.
• High-resolution Hi-C data and CRISPR-Cas9 technology were integrated for functional validation.

Main Results:

• MAE-seq identified hundreds of thousands of 25-bp enhancers in the studied cell types, with 626,879 in mESCs.
• A significant portion (33.85%) of identified enhancers were novel, lacking prior epigenetic modification.
• These 25-bp elements function as units, regulating gene expression similarly to larger elements, and enabling precise annotation of super enhancers.
• Over 55% of novel elements showed distal interactions with target genes, with functional validation confirming their role in gene expression and cell proliferation.

Conclusions:

• MAE-seq provides unprecedented resolution for identifying and annotating functional regulatory elements.
• The method reveals novel enhancers and their regulatory roles, advancing our understanding of genome organization and gene control.
• This approach enhances genome annotation precision and opens new avenues for exploring the genomic landscape and its regulatory mechanisms.