Somatic structural variant formation is guided by and influences genome architecture

Area of Science:

• Genomics
• Molecular Biology
• Epigenetics

Background:

• Genomic structural variants (SVs) arise from DNA breaks and rearrangements.
• 3D chromatin organization is implicated in SV formation, but mechanisms remain unclear.

Purpose of the Study:

• To investigate the interplay between 3D chromatin architecture and SV formation.
• To understand how SVs impact chromatin organization, replication timing, and gene regulation.

Main Methods:

• Hi-C experiments to map chromatin organization before and after inducing chromothripsis.
• Manual assembly of derivative chromosomes to analyze SV origins.
• Analysis of SV occurrence in relation to chromatin compartments and replication timing.

Main Results:

• Observed an action-reaction interplay between 3D chromatin and SV formation.
• SVs preferentially occur between similar chromatin compartments and replication timing regions.
• SVs frequently occur at 3D loop anchors and can switch chromatin states, impacting gene expression.

Conclusions:

• 3D chromatin architecture exerts a mechanistic bias on SV occurrence.
• SVs significantly reshape local chromatin topology, replication timing, and gene regulation.
• Findings supported by analysis of over 2700 cancer genomes.