Linear Interaction Between Replication and Transcription Shapes DNA Break Dynamics at Recurrent DNA Break Clusters

Area of Science:

• Genomics
• Molecular Biology
• Cell Biology

Background:

• Recurrent DNA break clusters (RDCs) are identified as critical sites of replication-transcription collisions, particularly prevalent in neural progenitor cells.
• Understanding the genomic features that determine RDC location and orientation is crucial for comprehending genome instability in these cells.

Approach:

• Utilized high-resolution replication sequencing and a capture-ligation assay in mouse neural progenitor cells under replication stress.
• Investigated replication fork dynamics and DNA:RNA hybrid formation at RDCs.
• Mapped RNA polymerase activity to assess the impact of replication-transcription interactions on DNA double-strand breaks (DSBs).

Key Points:

• RDCs predominantly occur at timing transition regions (TTRs) characterized by sparse origins and unidirectional forks.
• Leftward-moving replication forks are associated with telomere-connected DSBs, while rightward-moving forks yield centromere-connected DSBs.
• Increased density of DNA:RNA hybrids and head-on collisions between replication and transcription machinery contribute significantly to DSB formation.

Conclusions:

• Timing transition regions (TTRs) represent a novel class of fragile genomic sites.
• The linear interplay between transcription and replication processes fundamentally influences genome stability, particularly in neural progenitor cells.