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  • Genomic patterns of transcription-replication interactions in mouse primary B cells.

Genomic patterns of transcription-replication interactions in mouse primary B cells.

Nucleic acids research (2022-02-01)
Commodore P St Germain, Hongchang Zhao, Vrishti Sinha, Lionel A Sanz, Frédéric Chédin, Jacqueline H Barlow
ABSTRACT

Conflicts between transcription and replication machinery are a potent source of replication stress and genome instability; however, no technique currently exists to identify endogenous genomic locations prone to transcription-replication interactions. Here, we report a novel method to identify genomic loci prone to transcription-replication interactions termed transcription-replication immunoprecipitation on nascent DNA sequencing, TRIPn-Seq. TRIPn-Seq employs the sequential immunoprecipitation of RNA polymerase 2 phosphorylated at serine 5 (RNAP2s5) followed by enrichment of nascent DNA previously labeled with bromodeoxyuridine. Using TRIPn-Seq, we mapped 1009 unique transcription-replication interactions (TRIs) in mouse primary B cells characterized by a bimodal pattern of RNAP2s5, bidirectional transcription, an enrichment of RNA:DNA hybrids, and a high probability of forming G-quadruplexes. TRIs are highly enriched at transcription start sites and map to early replicating regions. TRIs exhibit enhanced Replication Protein A association and TRI-associated genes exhibit higher replication fork termination than control transcription start sites, two marks of replication stress. TRIs colocalize with double-strand DNA breaks, are enriched for deletions, and accumulate mutations in tumors. We propose that replication stress at TRIs induces mutations potentially contributing to age-related disease, as well as tumor formation and development.

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Interleukin-4 from mouse, IL-4, recombinant, expressed in E. coli, lyophilized powder, suitable for cell culture