DNA damage triggers heritable alterations in DNA methylation patterns in Arabidopsis

Area of Science:

• Genetics
• Molecular Biology
• Epigenetics

Background:

• DNA damage is hypothesized to induce DNA hypermethylation, potentially contributing to carcinogenesis.
• Evidence linking DNA damage to genome-wide DNA hypermethylation is insufficient.
• Understanding the epigenetic consequences of DNA damage is crucial for comprehending genome stability and evolution.

Purpose of the Study:

• To investigate whether DNA damage can induce genome-wide DNA hypermethylation in plants.
• To elucidate the mechanisms by which DNA damage affects DNA methylation patterns.
• To explore the functional implications of DNA damage-induced methylation.

Main Methods:

• Induction of DNA single-strand breaks with 3' blocked ends (DNA 3' blocks) in plants.
• Analysis of DNA methylation patterns (CG, CHG, CHH) using whole-genome bisulfite sequencing.
• Investigation of the roles of the DREAM complex and the RNA-directed DNA methylation (RdDM) pathway.
• Assessment of the effects of DNA damage repair and blocking the DNA damage response on methylation patterns.

Main Results:

• DNA 3' blocks reinforced existing DNA methylation and induced de novo methylation at normally nonmethylated loci.
• CG and CHG hypermethylation localized to gene bodies, while CHH hypermethylation concentrated in centromeric/pericentromeric regions.
• DNA 3' blocks regulated the DREAM complex for CG/CHG methylation and the RdDM pathway for CHH methylation.
• Repairing DNA damage or blocking the DNA damage response abolished CHH hypermethylation and partially rescued CHG hypermethylation, but minimally affected CG hypermethylation.

Conclusions:

• DNA damage is a significant driver of DNA methylation patterns and levels in plants.
• DNA damage-induced symmetric DNA methylation can function as a form of genetic imprinting.
• These findings reveal a novel link between DNA damage response and epigenetic regulation in plants.