Dynamic bimodal changes in CpG and non-CpG methylation genome-wide upon CGGBP1 loss-of-function

Area of Science:

• Genomics
• Epigenetics
• Molecular Biology

Background:

• CpG methylation is extensively studied, but mechanisms governing non-CpG methylation in mammals remain unclear.
• Proteins that bind DNA in a methylation-sensitive manner, like human CGGBP1, offer insights into cytosine methylation regulation.
• Understanding CGGBP1's role can elucidate novel pathways for epigenetic control.

Purpose of the Study:

• To investigate how CGGBP1 influences both CpG and non-CpG methylation.
• To analyze methylation states (CpG, CHG, CHH) in cells with and without CGGBP1 targeting.
• To identify the regulatory mechanisms employed by CGGBP1.

Main Methods:

• Resequencing of a published genome-wide bisulfite sequencing library.
• Base-level resolution analysis of CpG, CHG, and CHH methylation.
• Comparative analysis of methylation in CGGBP1-targeting versus non-targeting cells.

Main Results:

• CGGBP1 functions as a dynamic, bimodal regulator of DNA methylation.
• Methylation changes upon CGGBP1 depletion occurred in functional regions, associated with GC-skew, not specific motifs.
• Depletion led to clustered methylation changes near R-loop forming promoters (cis) and near transcription start sites of methylation regulatory genes (trans).

Conclusions:

• CGGBP1 regulates DNA methylation through both cis and trans-acting mechanisms.
• The study provides genome-wide estimates of CGGBP1-regulated methylation changes across all cytosine contexts.
• Findings shed light on the complex mechanisms controlling non-CpG methylation.