scholarly journals Emerging functions of Fanconi anemia genes in replication fork protection pathways

2020 ◽  
Vol 29 (R2) ◽  
pp. R158-R164 ◽  
Author(s):  
Arun Mouli Kolinjivadi ◽  
Wayne Crismani ◽  
Joanne Ngeow
Keyword(s):  
Dna Replication ◽  
Fanconi Anemia ◽  
Replication Fork ◽  
Genome Stability ◽  
Chromosome Instability ◽  
Replication Stress ◽  
Short Review ◽  
Gene Products ◽  
Dna Double Strand Breaks ◽  
Variants Of Unknown Significance

Abstract Germline mutations in Fanconi anemia (FA) genes predispose to chromosome instability syndromes, such as FA and cancers. FA gene products have traditionally been studied for their role in interstrand cross link (ICL) repair. A fraction of FA gene products are classical homologous recombination (HR) factors that are involved in repairing DNA double-strand breaks (DSBs) in an error-free manner. Emerging evidence suggests that, independent of ICL and HR repair, FA genes protect DNA replication forks in the presence of replication stress. Therefore, understanding the precise function of FA genes and their role in promoting genome stability in response to DNA replication stress is crucial for diagnosing FA and FA-associated cancers. Moreover, molecular understanding of the FA pathway will greatly help to establish proper functional assays for variants of unknown significance (VUS), often encountered in clinics. In this short review, we discuss the recently uncovered molecular details of FA genes in replication fork protection pathways. Finally, we examine how novel FA variants predispose to FA and cancer, due to defective replication fork protection activity.

scholarly journals MRE11-RAD50-NBS1 activates Fanconi Anemia R-loop suppression at transcription-replication conflicts

2018 ◽  
Author(s):  
Emily Yun-chia Chang ◽  
James P. Wells ◽  
Shu-Huei Tsai ◽  
Yan Coulombe ◽  
Yujia A. Chan ◽  
...  
Keyword(s):  
Dna Replication ◽  
Fanconi Anemia ◽  
Replication Fork ◽  
Genome Instability ◽  
Human Cancer ◽  
Replication Stress ◽  
Maintenance Factors ◽  
Genome Wide ◽  
A Genome ◽  
Dna Replication Stress

SUMMARYEctopic R-loop accumulation causes DNA replication stress and genome instability. To avoid these outcomes, cells possess a range of anti-R-loop mechanisms, including RNaseH that degrades the RNA moiety in R-loops. To comprehensively identify anti-R-loop mechanisms, we performed a genome-wide trigenic interaction screen in yeast lacking RNH1 and RNH201. We identified >100 genes critical for fitness in the absence of RNaseH, which were enriched for DNA replication fork maintenance factors such as RAD50. We show in yeast and human cells that R-loops accumulate during RAD50 depletion. In human cancer cell models, we find that RAD50 and its partners in the MRE11-RAD50-NBS1 complex regulate R-loop-associated DNA damage and replication stress. We show that a non-nucleolytic function of MRE11 is important for R-loop suppression via activation of PCNA-ubiquitination by RAD18 and recruiting anti-R-loop helicases in the Fanconi Anemia pathway. This work establishes a novel role for MRE11-RAD50-NBS1 in directing tolerance mechanisms of transcription-replication conflicts.

scholarly journals Functional cross talk between the Fanconi anemia and ATRX/DAXX histone chaperone pathways promotes replication fork recovery

2019 ◽  
Vol 29 (7) ◽  
pp. 1083-1095 ◽  
Author(s):  
Maya Raghunandan ◽  
Jung Eun Yeo ◽  
Ryan Walter ◽  
Kai Saito ◽  
Adam J Harvey ◽  
...  
Keyword(s):  
Fanconi Anemia ◽  
Replication Fork ◽  
Genome Stability ◽  
Chromosome Instability ◽  
Histone H3 ◽  
Underlying Mechanism ◽  
Replication Forks ◽  
Death Domain ◽  
Origin Firing ◽  
Stalled Replication Forks

Abstract Fanconi anemia (FA) is a chromosome instability syndrome characterized by increased cancer predisposition. Specifically, the FA pathway functions to protect genome stability during DNA replication. The central FA pathway protein, FANCD2, locates to stalled replication forks and recruits homologous recombination (HR) factors such as CtBP interacting protein (CtIP) to promote replication fork restart while suppressing new origin firing. Here, we identify alpha-thalassemia retardation syndrome X-linked (ATRX) as a novel physical and functional interaction partner of FANCD2. ATRX is a chromatin remodeler that forms a complex with Death domain-associated protein 6 (DAXX) to deposit the histone variant H3.3 into specific genomic regions. Intriguingly, ATRX was recently implicated in replication fork recovery; however, the underlying mechanism(s) remained incompletely understood. Our findings demonstrate that ATRX forms a constitutive protein complex with FANCD2 and protects FANCD2 from proteasomal degradation. ATRX and FANCD2 localize to stalled replication forks where they cooperate to recruit CtIP and promote MRE11 exonuclease-dependent fork restart while suppressing the firing of new replication origins. Remarkably, replication restart requires the concerted histone H3 chaperone activities of ATRX/DAXX and FANCD2, demonstrating that coordinated histone H3 variant deposition is a crucial event during the reinitiation of replicative DNA synthesis. Lastly, ATRX also cooperates with FANCD2 to promote the HR-dependent repair of directly induced DNA double-stranded breaks. We propose that ATRX is a novel functional partner of FANCD2 to promote histone deposition-dependent HR mechanisms in S-phase.

scholarly journals RNF4 Regulates the BLM Helicase in Recovery From Replication Fork Collapse

2021 ◽  
Vol 12 ◽  
Author(s):  
Nathan Ellis ◽  
Jianmei Zhu ◽  
Mary K Yagle ◽  
Wei-Chih Yang ◽  
Jing Huang ◽  
...  
Keyword(s):  
Dna Replication ◽  
Replication Fork ◽  
Replication Stress ◽  
Dna Helicase ◽  
Replication Forks ◽  
Replication Origins ◽  
Dna Double Strand Breaks ◽  
Response Factors ◽  
Fork Stalling ◽  
In Cells

Sumoylation is an important enhancer of responses to DNA replication stress and the SUMO-targeted ubiquitin E3 ligase RNF4 regulates these responses by ubiquitylation of sumoylated DNA damage response factors. The specific targets and functional consequences of RNF4 regulation in response to replication stress, however, have not been fully characterized. Here we demonstrated that RNF4 is required for the restart of DNA replication following prolonged hydroxyurea (HU)-induced replication stress. Contrary to its role in repair of γ-irradiation-induced DNA double-strand breaks (DSBs), our analysis revealed that RNF4 does not significantly impact recognition or repair of replication stress-associated DSBs. Rather, using DNA fiber assays, we found that the firing of new DNA replication origins, which is required for replication restart following prolonged stress, was inhibited in cells depleted of RNF4. We also provided evidence that RNF4 recognizes and ubiquitylates sumoylated Bloom syndrome DNA helicase BLM and thereby promotes its proteosome-mediated turnover at damaged DNA replication forks. Consistent with it being a functionally important RNF4 substrate, co-depletion of BLM rescued defects in the firing of new replication origins observed in cells depleted of RNF4 alone. We concluded that RNF4 acts to remove sumoylated BLM from collapsed DNA replication forks, which is required to facilitate normal resumption of DNA synthesis after prolonged replication fork stalling and collapse.

scholarly journals Wss1 promotes replication stress tolerance by degrading histones

2019 ◽  
Author(s):  
Karthik Maddi ◽  
Daniel Kwesi Sam ◽  
Florian Bonn ◽  
Stefan Prgomet ◽  
Eric Tulowetzke ◽  
...  
Keyword(s):  
Dna Replication ◽  
Protein Interactions ◽  
Replication Fork ◽  
Genome Stability ◽  
Replication Stress ◽  
Underlying Mechanism ◽  
Adverse Conditions ◽  
Replication Fork Progression ◽  
Timely Completion ◽  
Protein Crosslinks

SummaryTimely completion of DNA replication is central to accurate cell division and to the maintenance of genomic stability. However, certain DNA-protein interactions can physically impede DNA replication fork progression. Cells remove or bypass these physical impediments by different mechanisms to preserve DNA macromolecule integrity and genome stability. In Saccharomyces cerevisiae, Wss1, the DNA-protein crosslink repair protease, allows cells to tolerate hydroxyurea-induced replication stress but the underlying mechanism by which Wss1 promotes this function has remained unknown. Here we report that Wss1 provides cells tolerance to replication stress by directly degrading core histone subunits that non-specifically and non-covalently bind to single-stranded DNA. Unlike Wss1-dependent proteolysis of covalent DNA-protein crosslinks, proteolysis of histones does not require Cdc48 nor SUMO-binding activities. Wss1 thus acts as a multi-functional protease capable of targeting a broad range of covalent and non-covalent DNA-binding proteins to preserve genome stability during adverse conditions.

scholarly journals SDE2 Integrates into the TIMELESS-TIPIN Complex to Protect Stalled Replication Forks

2020 ◽  
Author(s):  
Julie Rageul ◽  
Jennifer J. Park ◽  
Ping Ping Zeng ◽  
Eun-A Lee ◽  
Jihyeon Yang ◽  
...  
Keyword(s):  
Dna Replication ◽  
Replication Fork ◽  
Genome Stability ◽  
Essential Role ◽  
Replication Stress ◽  
Replication Forks ◽  
Genomic Integrity ◽  
Fork Protection Complex ◽  
Stalled Replication Forks ◽  
Stalled Fork

ABSTRACTProtecting replication fork integrity during DNA replication is essential for maintaining genome stability. Here, we report that SDE2, a PCNA-associated protein, plays a key role in maintaining active replication and counteracting replication stress by regulating the replication fork protection complex (FPC). SDE2 directly interacts with the FPC component TIMELESS (TIM) and enhances TIM stability and its localization to replication forks, thereby aiding the coordination of replisome progression. Like TIM deficiency, knockdown of SDE2 leads to impaired fork progression and stalled fork recovery, along with a failure to activate CHK1 phosphorylation. Moreover, loss of SDE2 or TIM results in an excessive MRE11-dependent degradation of reversed forks. Together, our study uncovers an essential role for SDE2 in maintaining genomic integrity by stabilizing the FPC and describes a new role for TIM in protecting stalled replication forks. We propose that TIM-mediated fork protection may represent a way to cooperate with BRCA-dependent fork stabilization.

scholarly journals PARI Regulates Stalled Replication Fork Processing To Maintain Genome Stability upon Replication Stress in Mice

2017 ◽  
Vol 37 (23) ◽  
Author(s):  
Ayako L. Mochizuki ◽  
Ami Katanaya ◽  
Eri Hayashi ◽  
Mihoko Hosokawa ◽  
Emiko Moribe ◽  
...  
Keyword(s):  
Stem Cells ◽  
Dna Replication ◽  
Genome Stability ◽  
Ex Vivo ◽  
Chromosome Instability ◽  
Embryonic Stem ◽  
Replication Stress ◽  
Genotoxic Stress ◽  
Origin Firing

ABSTRACT DNA replication is frequently perturbed by intrinsic, as well as extrinsic, genotoxic stress. At damaged forks, DNA replication and repair activities require proper coordination to maintain genome integrity. We show here that PARI antirecombinase plays an essential role in modulating the initial response to replication stress in mice. PARI is functionally dormant at replisomes during normal replication, but upon replication stress, it enhances nascent-strand shortening that is regulated by RAD51 and MRE11. PARI then promotes double-strand break induction, followed by new origin firing instead of replication restart. Such PARI function is apparently obstructive to replication but is nonetheless physiologically required for chromosome stability in vivo and ex vivo. Of note, Pari-deficient embryonic stem cells exhibit spontaneous chromosome instability, which is attenuated by differentiation induction, suggesting that pluripotent stem cells have a preferential requirement for PARI that acts against endogenous replication stress. PARI is a latent modulator of stalled fork processing, which is required for stable genome inheritance under both endogenous and exogenous replication stress in mice.

scholarly journals SDE2 integrates into the TIMELESS-TIPIN complex to protect stalled replication forks

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Julie Rageul ◽  
Jennifer J. Park ◽  
Ping Ping Zeng ◽  
Eun-A Lee ◽  
Jihyeon Yang ◽  
...  
Keyword(s):  
Dna Replication ◽  
Replication Fork ◽  
Genome Stability ◽  
Essential Role ◽  
Replication Stress ◽  
Replication Forks ◽  
Genomic Integrity ◽  
Fork Protection Complex ◽  
Stalled Replication Forks ◽  
Stalled Fork

Abstract Protecting replication fork integrity during DNA replication is essential for maintaining genome stability. Here, we report that SDE2, a PCNA-associated protein, plays a key role in maintaining active replication and counteracting replication stress by regulating the replication fork protection complex (FPC). SDE2 directly interacts with the FPC component TIMELESS (TIM) and enhances its stability, thereby aiding TIM localization to replication forks and the coordination of replisome progression. Like TIM deficiency, knockdown of SDE2 leads to impaired fork progression and stalled fork recovery, along with a failure to activate CHK1 phosphorylation. Moreover, loss of SDE2 or TIM results in an excessive MRE11-dependent degradation of reversed forks. Together, our study uncovers an essential role for SDE2 in maintaining genomic integrity by stabilizing the FPC and describes a new role for TIM in protecting stalled replication forks. We propose that TIM-mediated fork protection may represent a way to cooperate with BRCA-dependent fork stabilization.

scholarly journals DNA-Replikationsstress, Mitose und genomische Instabilität

BIOspektrum ◽  
2021 ◽  
Vol 27 (1) ◽  
pp. 10-13
Author(s):  
Alicia Konrath ◽  
Ann-Kathrin Schmidt ◽  
Holger Bastians
Keyword(s):  
Dna Replication ◽  
Tumor Progression ◽  
Chromosome Aberrations ◽  
Chromosomal Instability ◽  
Chromosome Instability ◽  
Replication Stress ◽  
Functional Link ◽  
Structural Chromosome ◽  
Genomische Instabilität

AbstractChromosomal instability (CIN) is a hallmark of cancer and contributes to tumorigenesis and tumor progression. While structural CIN (S-CIN) leads to structural chromosome aberrations, whole chromosome instability (W-CIN) is defined by perpetual gains or losses of chromosomes during mitosis causing aneuploidy. Mitotic defects, but also abnormal DNA replication (replication stress) can lead to W-CIN. However, the functional link between replication stress, mitosis and aneuploidy is little understood.

scholarly journals Coordinated Degradation of Replisome Components Ensures Genome Stability upon Replication Stress in the Absence of the Replication Fork Protection Complex

PLoS Genetics ◽  
2013 ◽  
Vol 9 (1) ◽  
pp. e1003213 ◽  
Author(s):  
Laura C. Roseaulin ◽  
Chiaki Noguchi ◽  
Esteban Martinez ◽  
Melissa A. Ziegler ◽  
Takashi Toda ◽  
...  
Keyword(s):  
Replication Fork ◽  
Genome Stability ◽  
Replication Stress ◽  
Fork Protection Complex

scholarly journals Acetylation modulates the Fanconi anemia pathway by protecting FAAP20 from ubiquitin-mediated proteasomal degradation

2020 ◽  
Vol 295 (40) ◽  
pp. 13887-13901
Author(s):  
Bhavika Nagareddy ◽  
Arafat Khan ◽  
Hyungjin Kim
Keyword(s):  
Fanconi Anemia ◽  
Posttranslational Modifications ◽  
Genome Stability ◽  
Chromosome Instability ◽  
Lysine Residue ◽  
Core Complex ◽  
Ubiquitin E3 Ligase ◽  
Pathway Activation ◽  
Anemia Group ◽  
Inherited Mutations

Fanconi anemia (FA) is a chromosome instability syndrome of children caused by inherited mutations in one of FA genes, which together constitute a DNA interstrand cross-link (ICL) repair, or the FA pathway. Monoubiquitination of Fanconi anemia group D2 protein (FANCD2) by the multisubunit ubiquitin E3 ligase, the FA core complex, is an obligate step in activation of the FA pathway, and its activity needs to be tightly regulated. FAAP20 is a key structural component of the FA core complex, and regulated proteolysis of FAAP20 mediated by prolyl cis-trans isomerization and phosphorylation at a consensus phosphodegron motif is essential for preserving the integrity of the FA core complex, and thus FANCD2 monoubiquitination. However, how ubiquitin-dependent FAAP20 degradation is modulated to fine-tune FA pathway activation remains largely un-known. Here, we present evidence that FAAP20 is acetylated by the acetyltransferase p300/CBP on lysine 152, the key residue that when polyubiquitinated results in the degradation of FAAP20. Acetylation or mutation of the lysine residue stabilizes FAAP20 by preventing its ubiquitination, thereby protecting it from proteasome-dependent FAAP20 degradation. Consequently, disruption of the FAAP20 acetylation pathway impairs FANCD2 activation. Together, our study reveals a competition mechanism between ubiquitination and acetylation of a common lysine residue that controls FAAP20 stability and highlights a complex balancing between different posttranslational modifications as a way to refine the FA pathway signaling required for DNA ICL repair and genome stability.

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