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Mechanisms of insertions at a double strand break

ABSTRACT: Insertions and deletions (indels) are common sources of structural variation, and insertions originating from spontaneous DNA lesions are frequent in cancer. We developed a highly sensitive assay (Indel-Seq) to monitor rearrangements in human cells at the TRIM37 acceptor locus that reports indels stemming from experimentallyinduced and spontaneous genome instability. Templated insertions, which derive from sequences genome-wide, require contact between donor and acceptor loci, homologous recombination, and are stimulated by DNA end-processing. Insertions are facilitated by transcription and involve a DNA/RNA hybrid intermediate. Indel-Seq reveals that insertions are generated via multiple pathways. The broken acceptor site anneals with a resected DNA break or invades the displaced strand of a transcription bubble or R-loop followed by DNA synthesis, displacement and then ligation by nonhomologous end-joining. Our studies identify transcription-coupled insertions as a critical source of spontaneous genome instability that are distinct from cut-and-paste events

ORGANISM(S): Homo sapiens

PROVIDER: GSE234089 | GEO | 2023/07/03

REPOSITORIES: GEO

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