DNA double-strand breaks (DSBs) represent a lethal form of DNA damage that can trigger cell death or initiate oncogenesis. The activity of RNA polymerase II (RNAPII) at the break site is required for efficient DSB repair. However, the regulatory mechanisms governing the transcription cycle at DSBs are not well understood. Here, we show that Integrator complex subunit 6 (INTS6) associates with the heterotrimeric sensor of ssDNA (SOSS1) complex (comprising INTS3, INIP and hSSB1) to form the tetrameric SOSS1 complex. INTS6 binds to DNA:RNA hybrids and promotes Protein Phosphatase 2A (PP2A) recruitment to DSBs, facilitating the dephosphorylation of RNAPII. Furthermore, INTS6 prevents the accumulation of damage-associated RNA transcripts (DARTs) and the stabilization of DNA:RNA hybrids at DSB sites. INTS6 interacts with and promotes the recruitment of senataxin (SETX) to DSBs, facilitating the resolution of DNA:RNA hybrids/R-loops. Our results underscore the significance of the tetrameric SOSS1 complex in the autoregulation of DNA:RNA hybrids and efficient DNA repair.

• MeSH
• DNA-Binding Proteins metabolism   MeSH
• DNA Helicases metabolism   genetics   MeSH
• DNA * metabolism   chemistry   MeSH
• DNA Breaks, Double-Stranded * MeSH
• Phosphorylation MeSH
• Homeostasis genetics   MeSH
• Humans MeSH
• DNA Repair * MeSH
• Protein Phosphatase 2 metabolism   genetics   MeSH
• R-Loop Structures MeSH
• RNA Helicases metabolism   genetics   MeSH
• RNA Polymerase II * metabolism   MeSH
• RNA * metabolism   genetics   chemistry   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• DNA-Binding Proteins MeSH
• DNA Helicases MeSH
• DNA * MeSH
• Protein Phosphatase 2 MeSH
• RNA Helicases MeSH
• RNA Polymerase II * MeSH
• RNA * MeSH

Replication forks stalled at co-transcriptional R-loops can be restarted by a mechanism involving fork cleavage-religation cycles mediated by MUS81 endonuclease and DNA ligase IV (LIG4), which presumably relieve the topological barrier generated by the transcription-replication conflict (TRC) and facilitate ELL-dependent reactivation of transcription. Here, we report that the restart of R-loop-stalled replication forks via the MUS81-LIG4-ELL pathway requires senataxin (SETX), a helicase that can unwind RNA:DNA hybrids. We found that SETX promotes replication fork progression by preventing R-loop accumulation during S-phase. Interestingly, loss of SETX helicase activity leads to nascent DNA degradation upon induction of R-loop-mediated fork stalling by hydroxyurea. This fork degradation phenotype is independent of replication fork reversal and results from DNA2-mediated resection of MUS81-cleaved replication forks that accumulate due to defective replication restart. Finally, we demonstrate that SETX acts in a common pathway with the DEAD-box helicase DDX17 to suppress R-loop-mediated replication stress in human cells. A possible cooperation between these RNA/DNA helicases in R-loop unwinding at TRC sites is discussed.

• MeSH
• Flap Endonucleases metabolism   genetics   MeSH
• DEAD-box RNA Helicases * metabolism   genetics   MeSH
• DNA-Binding Proteins * metabolism   genetics   MeSH
• DNA Helicases * metabolism   genetics   MeSH
• DNA Ligase ATP metabolism   genetics   MeSH
• DNA metabolism   genetics   MeSH
• Endonucleases * metabolism   genetics   MeSH
• Transcription, Genetic MeSH
• Humans MeSH
• Multifunctional Enzymes * metabolism   genetics   MeSH
• R-Loop Structures * MeSH
• DNA Replication * MeSH
• RNA Helicases * metabolism   genetics   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Flap Endonucleases MeSH
• DEAD-box RNA Helicases * MeSH
• DNA-Binding Proteins * MeSH
• DNA Helicases * MeSH
• DNA Ligase ATP MeSH
• DNA MeSH
• Endonucleases * MeSH
• Multifunctional Enzymes * MeSH
• MUS81 protein, human MeSH Browser
• RNA Helicases * MeSH
• SETX protein, human MeSH Browser