Replication stress, particularly in hard-to-replicate regions such as telomeres and centromeres, leads to the accumulation of replication intermediates that must be processed to ensure proper chromosome segregation. In this study, we identify a critical role for the interaction between RECQ4 and MUS81 in managing such stress. We show that RECQ4 physically interacts with MUS81, targeting it to specific DNA substrates and enhancing its endonuclease activity. Loss of this interaction, results in significant chromosomal segregation defects, including the accumulation of micronuclei, anaphase bridges, and ultrafine bridges (UFBs). Our data further demonstrate that the RECQ4-MUS81 interaction plays an important role in ALT-positive cells, where MUS81 foci primarily colocalise with telomeres, highlighting its role in telomere maintenance. We also observe that a mutation associated with Rothmund-Thomson syndrome, which produces a truncated RECQ4 unable to interact with MUS81, recapitulates these chromosome instability phenotypes. This underscores the importance of RECQ4-MUS81 in safeguarding genome integrity and suggests potential implications for human disease. Our findings demonstrate the RECQ4-MUS81 interaction as a key mechanism in alleviating replication stress at hard-to-replicate regions and highlight its relevance in pathological conditions such as RTS.

• MeSH
• chromozomální nestabilita MeSH
• DNA vazebné proteiny * metabolismus   genetika   MeSH
• endonukleasy MeSH
• helikasy RecQ * metabolismus   genetika   MeSH
• homeostáza telomer * MeSH
• lidé MeSH
• mutace MeSH
• replikace DNA MeSH
• Rothmundův-Thomsonův syndrom * genetika   metabolismus   MeSH
• segregace chromozomů MeSH
• telomery * metabolismus   genetika   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• DNA vazebné proteiny * MeSH
• endonukleasy MeSH
• helikasy RecQ * MeSH
• MUS81 protein, human MeSH Prohlížeč
• RECQL4 protein, human MeSH Prohlížeč

Prolonged pausing of the transcription machinery may lead to the formation of three-stranded nucleic acid structures, called R-loops, typically resulting from the annealing of the nascent RNA with the template DNA. Unscheduled persistence of R-loops and RNA polymerases may interfere with transcription itself and other essential processes such as DNA replication and repair. Senataxin (SETX) is a putative helicase, mutated in two neurodegenerative disorders, which has been implicated in the control of R-loop accumulation and in transcription termination. However, understanding the precise role of SETX in these processes has been precluded by the absence of a direct characterisation of SETX biochemical activities. Here, we purify and characterise the helicase domain of SETX in parallel with its yeast orthologue, Sen1. Importantly, we show that SETX is a bona fide helicase with the ability to resolve R-loops. Furthermore, SETX has retained the transcription termination activity of Sen1 but functions in a species-specific manner. Finally, subsequent characterisation of two SETX variants harbouring disease-associated mutations shed light into the effect of such mutations on SETX folding and biochemical properties. Altogether, these results broaden our understanding of SETX function in gene expression and the maintenance of genome integrity and provide clues to elucidate the molecular basis of SETX-associated neurodegenerative diseases.

• MeSH
• DNA-helikasy * genetika   metabolismus   MeSH
• genetická transkripce MeSH
• lidé MeSH
• multifunkční enzymy genetika   metabolismus   MeSH
• neurodegenerativní nemoci MeSH
• R-smyčka MeSH
• regulace genové exprese MeSH
• RNA-helikasy * metabolismus   MeSH
• Saccharomyces cerevisiae - proteiny metabolismus   MeSH
• Saccharomyces cerevisiae metabolismus   MeSH
• terminace genetické transkripce * MeSH
• transkripční faktory genetika   metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• DNA-helikasy * MeSH
• multifunkční enzymy MeSH
• RNA-helikasy * MeSH
• Saccharomyces cerevisiae - proteiny MeSH
• SEN1 protein, S cerevisiae MeSH Prohlížeč
• SETX protein, human MeSH Prohlížeč
• transkripční faktory MeSH

R-loops are three-stranded nucleic acid structures composed of an RNA:DNA hybrid and displaced DNA strand. These structures can halt DNA replication when formed co-transcriptionally in the opposite orientation to replication fork progression. A recent study has shown that replication forks stalled by co-transcriptional R-loops can be restarted by a mechanism involving fork cleavage by MUS81 endonuclease, followed by ELL-dependent reactivation of transcription, and fork religation by the DNA ligase IV (LIG4)/XRCC4 complex. However, how R-loops are eliminated to allow the sequential restart of transcription and replication in this pathway remains elusive. Here, we identified the human DDX17 helicase as a factor that associates with R-loops and counteracts R-loop-mediated replication stress to preserve genome stability. We show that DDX17 unwinds R-loops in vitro and promotes MUS81-dependent restart of R-loop-stalled forks in human cells in a manner dependent on its helicase activity. Loss of DDX17 helicase induces accumulation of R-loops and the formation of R-loop-dependent anaphase bridges and micronuclei. These findings establish DDX17 as a component of the MUS81-LIG4-ELL pathway for resolution of R-loop-mediated transcription-replication conflicts, which may be involved in R-loop unwinding.

• MeSH
• DEAD-box RNA-helikasy genetika   metabolismus   MeSH
• DNA-helikasy metabolismus   MeSH
• DNA metabolismus   MeSH
• endonukleasy metabolismus   MeSH
• lidé MeSH
• R-smyčka * MeSH
• replikace DNA * genetika   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• DDX17 protein, human MeSH Prohlížeč
• DEAD-box RNA-helikasy MeSH
• DNA-helikasy MeSH
• DNA MeSH
• endonukleasy MeSH

RECQ5 belongs to the RecQ family of DNA helicases. It is conserved from Drosophila to humans and its deficiency results in genomic instability and cancer susceptibility in mice. Human RECQ5 is known for its ability to regulate homologous recombination by disrupting RAD51 nucleoprotein filaments. It also binds to RNA polymerase II (RNAPII) and negatively regulates transcript elongation by RNAPII. Here, we summarize recent studies implicating RECQ5 in the prevention and resolution of transcription-replication conflicts, a major intrinsic source of genomic instability during cancer development.

• Klíčová slova
• DNA repair, R-loops, RECQ5, genomic instability, replication stress, transcription-replication conflicts,
• MeSH
• DNA genetika   metabolismus   MeSH
• genetická transkripce genetika   MeSH
• helikasy RecQ genetika   metabolismus   fyziologie   MeSH
• lidé MeSH
• nestabilita genomu MeSH
• replikace DNA MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• DNA MeSH
• helikasy RecQ MeSH

The MUS81-EME1 endonuclease cleaves late replication intermediates at common fragile sites (CFSs) during early mitosis to trigger DNA-repair synthesis that ensures faithful chromosome segregation. Here, we show that these DNA transactions are promoted by RECQ5 DNA helicase in a manner dependent on its Ser727 phosphorylation by CDK1. Upon replication stress, RECQ5 associates with CFSs in early mitosis through its physical interaction with MUS81 and promotes MUS81-dependent mitotic DNA synthesis. RECQ5 depletion or mutational inactivation of its ATP-binding site, RAD51-interacting domain, or phosphorylation site causes excessive binding of RAD51 to CFS loci and impairs CFS expression. This leads to defective chromosome segregation and accumulation of CFS-associated DNA damage in G1 cells. Biochemically, RECQ5 alleviates the inhibitory effect of RAD51 on 3'-flap DNA cleavage by MUS81-EME1 through its RAD51 filament disruption activity. These data suggest that RECQ5 removes RAD51 filaments stabilizing stalled replication forks at CFSs and hence facilitates CFS cleavage by MUS81-EME1.

• Klíčová slova
• MUS81, RAD51 filament, RECQ5, common fragile sites, genomic instability, mitotic DNA synthesis, replication stress,
• MeSH
• časové faktory MeSH
• chromozomální nestabilita MeSH
• cyklin-dependentní kinasy metabolismus   MeSH
• DNA vazebné proteiny genetika   metabolismus   MeSH
• DNA biosyntéza   genetika   MeSH
• endodeoxyribonukleasy metabolismus   MeSH
• endonukleasy genetika   metabolismus   MeSH
• fosforylace MeSH
• fragilní místa na chromozomu * MeSH
• HEK293 buňky MeSH
• HeLa buňky MeSH
• helikasy RecQ genetika   metabolismus   MeSH
• lidé MeSH
• mitóza * MeSH
• oprava DNA * MeSH
• poškození DNA MeSH
• proteinkinasa CDC2 MeSH
• rekombinasa Rad51 metabolismus   MeSH
• replikační počátek * MeSH
• RNA interference MeSH
• segregace chromozomů MeSH
• transfekce MeSH
• vazba proteinů MeSH
• vazebná místa MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• CDK1 protein, human MeSH Prohlížeč
• cyklin-dependentní kinasy MeSH
• DNA vazebné proteiny MeSH
• DNA MeSH
• Eme1 protein, human MeSH Prohlížeč
• endodeoxyribonukleasy MeSH
• endonukleasy MeSH
• helikasy RecQ MeSH
• MUS81 protein, human MeSH Prohlížeč
• proteinkinasa CDC2 MeSH
• RAD51 protein, human MeSH Prohlížeč
• RECQL5 protein, human MeSH Prohlížeč
• rekombinasa Rad51 MeSH