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Honda M, Razzaghi M, Gaur P, Malacaria E, Di Biagi L, Aiello FA, Paintsil EA, Stanfield A, Deppe BJ, Gakhar L, Schnicker NJ, Spies MA, Pichierri P, Spies M. Human RAD52 double-ring remodels replication forks restricting fork reversal. bioRxiv 2023:2023.11.14.566657. [PMID: 38014173 PMCID: PMC10680749 DOI: 10.1101/2023.11.14.566657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Human RAD52 1,2 is a multifunctional DNA repair protein involved in several cellular events that support genome stability including protection of stalled DNA replication forks from excessive degradation 3-7 . In its gatekeeper role, RAD52 binds to and stabilizes stalled replication forks during replication stress protecting them from reversal by SMARCAL1 5 . The structural and molecular mechanism of the RAD52-mediated fork protection remains elusive. Here, using P1 nuclease sensitivity, biochemical and single-molecule analyses we show that RAD52 dynamically remodels replication forks through its strand exchange activity. The presence of the ssDNA binding protein RPA at the fork modulates the kinetics of the strand exchange without impeding the reaction outcome. Mass photometry and single-particle cryo-electron microscopy show that the replication fork promotes a unique nucleoprotein structure containing head-to-head arrangement of two undecameric RAD52 rings with an extended positively charged surface that accommodates all three arms of the replication fork. We propose that the formation and continuity of this surface is important for the strand exchange reaction and for competition with SMARCAL1.
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2
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Bhat D, Malacaria E, Biagi L, Razzaghi M, Honda M, Hobbs K, Hengel S, Pichierri P, Spies M, Spies M. Therapeutic disruption of RAD52-ssDNA complexation via novel drug-like inhibitors. NAR Cancer 2023; 5:zcad018. [PMID: 37139244 PMCID: PMC10150327 DOI: 10.1093/narcan/zcad018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 04/09/2023] [Accepted: 04/14/2023] [Indexed: 05/05/2023] Open
Abstract
RAD52 protein is a coveted target for anticancer drug discovery. Similar to poly-ADP-ribose polymerase (PARP) inhibitors, pharmacological inhibition of RAD52 is synthetically lethal with defects in genome caretakers BRCA1 and BRCA2 (∼25% of breast and ovarian cancers). Emerging structure activity relationships for RAD52 are complex, making it challenging to transform previously identified disruptors of the RAD52-ssDNA interaction into drug-like leads using traditional medicinal chemistry approaches. Using pharmacophoric informatics on the RAD52 complexation by epigallocatechin (EGC), and the Enamine in silico REAL database, we identified six distinct chemical scaffolds that occupy the same physical space on RAD52 as EGC. All six were RAD52 inhibitors (IC50 ∼23-1200 μM) with two of the compounds (Z56 and Z99) selectively killing BRCA-mutant cells and inhibiting cellular activities of RAD52 at micromolar inhibitor concentrations. While Z56 had no effect on the ssDNA-binding protein RPA and was toxic to BRCA-mutant cells only, Z99 inhibited both proteins and displayed toxicity towards BRCA-complemented cells. Optimization of the Z99 scaffold resulted in a set of more powerful and selective inhibitors (IC50 ∼1.3-8 μM), which were only toxic to BRCA-mutant cells. RAD52 complexation by Z56, Z99 and its more specific derivatives provide a roadmap for next generation of cancer therapeutics.
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Affiliation(s)
- Divya S Bhat
- Department of Biochemistry, University of Iowa Carver College of Medicine, 51 Newton Road, Iowa City, IA 52242, USA
| | - Eva Malacaria
- Mechanisms, Biomarkers and Models Section, Department of Environment and Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy
| | - Ludovica Di Biagi
- Mechanisms, Biomarkers and Models Section, Department of Environment and Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy
| | - Mortezaali Razzaghi
- Department of Biochemistry, University of Iowa Carver College of Medicine, 51 Newton Road, Iowa City, IA 52242, USA
| | - Masayoshi Honda
- Department of Biochemistry, University of Iowa Carver College of Medicine, 51 Newton Road, Iowa City, IA 52242, USA
| | - Kathryn F Hobbs
- Department of Biochemistry, University of Iowa Carver College of Medicine, 51 Newton Road, Iowa City, IA 52242, USA
- Division of Medicinal and Natural Products Chemistry, Department of Pharmaceutical Sciences and Experimental Therapeutics, The University of Iowa, Iowa City, IA 52242, USA
| | - Sarah R Hengel
- Department of Biochemistry, University of Iowa Carver College of Medicine, 51 Newton Road, Iowa City, IA 52242, USA
| | - Pietro Pichierri
- Mechanisms, Biomarkers and Models Section, Department of Environment and Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy
| | - M Ashley Spies
- Department of Biochemistry, University of Iowa Carver College of Medicine, 51 Newton Road, Iowa City, IA 52242, USA
- Division of Medicinal and Natural Products Chemistry, Department of Pharmaceutical Sciences and Experimental Therapeutics, The University of Iowa, Iowa City, IA 52242, USA
- Naturis Informatika LLC, 401 Mullin Ave., Iowa City, IA 52246, USA
| | - Maria Spies
- Department of Biochemistry, University of Iowa Carver College of Medicine, 51 Newton Road, Iowa City, IA 52242, USA
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Blandino F, Malacaria E, Figlioli C, Noto A, Pugliese GM, Franchitto A, Pichierri P. Phosphorylation status of MUS81 is a modifier of Olaparib sensitivity in BRCA2-deficient cells. Nucleic Acids Res 2023:7186995. [PMID: 37254810 PMCID: PMC10359636 DOI: 10.1093/nar/gkad470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 05/05/2023] [Accepted: 05/15/2023] [Indexed: 06/01/2023] Open
Abstract
The MUS81 complex is crucial for preserving genome stability through resolution of branched DNA intermediates in mitosis and also for the processing of deprotected replication forks in BRCA2-deficient cells. Because of the existence of two different MUS81 complexes in mammalian cells that act in M- or S-phase, whether and how the PARPi sensitivity of BRCA2-deficient cells is affected by loss of MUS81 function is unclear. Here, using a mutant of MUS81 that impairs its function in M-phase, we show that viability of BRCA2-deficient cells but not their PARPi sensitivity requires a fully-functional MUS81 complex in mitosis. In contrast, expression of a constitutively-active MUS81 is sufficient to confer PARPi resistance. From a mechanistic point of view, our data indicate that deregulated action of the mitotic active form of MUS81 in S-phase leads to the cleavage of stalled replication forks before their reversal, bypassing fork deprotection, and engaging a Polθ-dependent DSBs repair. Collectively, our findings describe a novel mechanism leading to PARPi resistance that involves unscheduled MUS81-dependent cleavage of intact, unreversed replication forks. Since this cleavage occurs mimicking the phosphorylated status of S87 of MUS81, our data suggest that hyperphosphorylation of this residue in S-phase might represent a novel biomarker to identify resistance to PARPi.
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Affiliation(s)
- Francesca Blandino
- Mechanisms, Biomarkers and Models Unit, Department of Environment and Health, Istituto Superiore di Sanità - Viale Regina Elena 299, 00161 Rome, Italy
| | - Eva Malacaria
- Mechanisms, Biomarkers and Models Unit, Department of Environment and Health, Istituto Superiore di Sanità - Viale Regina Elena 299, 00161 Rome, Italy
| | - Carolina Figlioli
- Mechanisms, Biomarkers and Models Unit, Department of Environment and Health, Istituto Superiore di Sanità - Viale Regina Elena 299, 00161 Rome, Italy
| | - Alessandro Noto
- Mechanisms, Biomarkers and Models Unit, Department of Environment and Health, Istituto Superiore di Sanità - Viale Regina Elena 299, 00161 Rome, Italy
- Istituto Nazionale Biostrutture e Biosistemi - Roma Area Research Unit - Via delle Medaglie d'Oro 305, 00136 Rome, Italy
| | - Giusj Monia Pugliese
- Mechanisms, Biomarkers and Models Unit, Department of Environment and Health, Istituto Superiore di Sanità - Viale Regina Elena 299, 00161 Rome, Italy
| | - Annapaola Franchitto
- Mechanisms, Biomarkers and Models Unit, Department of Environment and Health, Istituto Superiore di Sanità - Viale Regina Elena 299, 00161 Rome, Italy
| | - Pietro Pichierri
- Mechanisms, Biomarkers and Models Unit, Department of Environment and Health, Istituto Superiore di Sanità - Viale Regina Elena 299, 00161 Rome, Italy
- Istituto Nazionale Biostrutture e Biosistemi - Roma Area Research Unit - Via delle Medaglie d'Oro 305, 00136 Rome, Italy
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Di Biagi L, Malacaria E, Aiello FA, Valenzisi P, Marozzi G, Franchitto A, Pichierri P. RAD52 prevents accumulation of Polα-dependent replication gaps at perturbed replication forks in human cells. bioRxiv 2023:2023.04.12.536536. [PMID: 37090680 PMCID: PMC10120653 DOI: 10.1101/2023.04.12.536536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
Replication gaps can arise as a consequence of perturbed DNA replication and their accumulation might undermine the stability of the genome. Loss of RAD52, a protein involved in the regulation of fork reversal, promotes accumulation of parental ssDNA gaps during replication perturbation. Here, we demonstrate that this is due to the engagement of Polα downstream of the extensive degradation of perturbed replication forks after their reversal, and is not dependent on PrimPol. Polα is hyper-recruited at parental ssDNA in the absence of RAD52, and this recruitment is dependent on fork reversal enzymes and RAD51. Of note, we report that the interaction between Polα and RAD51 is stimulated by RAD52 inhibition, and Polα-dependent gap accumulation requires nucleation of RAD51 suggesting that it occurs downstream strand invasion. Altogether, our data indicate that RAD51-Polα-dependent repriming is essential to promote fork restart and limit DNA damage accumulation when RAD52 function is disabled.
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Affiliation(s)
- Ludovica Di Biagi
- Mechanisms, Biomarkers and Models Section, Department of Environment and Health, Istituto Superiore di Sanità - Viale Regina Elena 299, 00161 Rome (Italy)
- Istituto Nazionale Biostrutture e Biosistemi - Roma Area Research Unit - Via delle Medaglie d’Oro 305, 00136 Rome (Italy)
| | - Eva Malacaria
- Mechanisms, Biomarkers and Models Section, Department of Environment and Health, Istituto Superiore di Sanità - Viale Regina Elena 299, 00161 Rome (Italy)
| | - Francesca Antonella Aiello
- Mechanisms, Biomarkers and Models Section, Department of Environment and Health, Istituto Superiore di Sanità - Viale Regina Elena 299, 00161 Rome (Italy)
- Istituto Nazionale Biostrutture e Biosistemi - Roma Area Research Unit - Via delle Medaglie d’Oro 305, 00136 Rome (Italy)
| | - Pasquale Valenzisi
- Mechanisms, Biomarkers and Models Section, Department of Environment and Health, Istituto Superiore di Sanità - Viale Regina Elena 299, 00161 Rome (Italy)
| | - Giorgia Marozzi
- Mechanisms, Biomarkers and Models Section, Department of Environment and Health, Istituto Superiore di Sanità - Viale Regina Elena 299, 00161 Rome (Italy)
| | - Annapaola Franchitto
- Mechanisms, Biomarkers and Models Section, Department of Environment and Health, Istituto Superiore di Sanità - Viale Regina Elena 299, 00161 Rome (Italy)
| | - Pietro Pichierri
- Mechanisms, Biomarkers and Models Section, Department of Environment and Health, Istituto Superiore di Sanità - Viale Regina Elena 299, 00161 Rome (Italy)
- Istituto Nazionale Biostrutture e Biosistemi - Roma Area Research Unit - Via delle Medaglie d’Oro 305, 00136 Rome (Italy)
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Marabitti V, Valenzisi P, Lillo G, Malacaria E, Palermo V, Pichierri P, Franchitto A. R-Loop-Associated Genomic Instability and Implication of WRN and WRNIP1. Int J Mol Sci 2022; 23:ijms23031547. [PMID: 35163467 PMCID: PMC8836129 DOI: 10.3390/ijms23031547] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 01/25/2022] [Accepted: 01/25/2022] [Indexed: 02/05/2023] Open
Abstract
Maintenance of genome stability is crucial for cell survival and relies on accurate DNA replication. However, replication fork progression is under constant attack from different exogenous and endogenous factors that can give rise to replication stress, a source of genomic instability and a notable hallmark of pre-cancerous and cancerous cells. Notably, one of the major natural threats for DNA replication is transcription. Encounters or conflicts between replication and transcription are unavoidable, as they compete for the same DNA template, so that collisions occur quite frequently. The main harmful transcription-associated structures are R-loops. These are DNA structures consisting of a DNA–RNA hybrid and a displaced single-stranded DNA, which play important physiological roles. However, if their homeostasis is altered, they become a potent source of replication stress and genome instability giving rise to several human diseases, including cancer. To combat the deleterious consequences of pathological R-loop persistence, cells have evolved multiple mechanisms, and an ever growing number of replication fork protection factors have been implicated in preventing/removing these harmful structures; however, many others are perhaps still unknown. In this review, we report the current knowledge on how aberrant R-loops affect genome integrity and how they are handled, and we discuss our recent findings on the role played by two fork protection factors, the Werner syndrome protein (WRN) and the Werner helicase-interacting protein 1 (WRNIP1) in response to R-loop-induced genome instability.
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6
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Marabitti V, Lillo G, Malacaria E, Palermo V, Pichierri P, Franchitto A. Checkpoint Defects Elicit a WRNIP1-Mediated Response to Counteract R-Loop-Associated Genomic Instability. Cancers (Basel) 2020; 12:cancers12020389. [PMID: 32046194 PMCID: PMC7072626 DOI: 10.3390/cancers12020389] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 02/03/2020] [Accepted: 02/05/2020] [Indexed: 12/04/2022] Open
Abstract
Conflicts between replication and transcription are a common source of genomic instability, a characteristic of almost all human cancers. Aberrant R-loops can cause a block to replication fork progression. A growing number of factors are involved in the resolution of these harmful structures and many perhaps are still unknown. Here, we reveal that the Werner interacting protein 1 (WRNIP1)-mediated response is implicated in counteracting aberrant R-loop accumulation. Using human cellular models with compromised Ataxia-Telangiectasia and Rad3-Related (ATR)-dependent checkpoint activation, we show that WRNIP1 is stabilized in chromatin and is needed for maintaining genome integrity by mediating the Ataxia Telangiectasia Mutated (ATM)-dependent phosphorylation of Checkpoint kinase 1 (CHK1). Furthermore, we demonstrated that loss of Werner Syndrome protein (WRN) or ATR signaling leads to formation of R-loop-dependent parental ssDNA upon mild replication stress, which is covered by Radiorestistance protein 51 (RAD51). We prove that Werner helicase-interacting protein 1 (WRNIP1) chromatin retention is also required to stabilize the association of RAD51 with ssDNA in proximity of R-loops. Therefore, in these pathological contexts, ATM inhibition or WRNIP1 abrogation is accompanied by increased levels of genomic instability. Overall, our findings suggest a novel function for WRNIP1 in preventing R-loop-driven genome instability, providing new clues to understand the way replication–transcription conflicts are handled.
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Aiello FA, Palma A, Malacaria E, Zheng L, Campbell JL, Shen B, Franchitto A, Pichierri P. RAD51 and mitotic function of mus81 are essential for recovery from low-dose of camptothecin in the absence of the WRN exonuclease. Nucleic Acids Res 2020; 47:6796-6810. [PMID: 31114910 PMCID: PMC6648349 DOI: 10.1093/nar/gkz431] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Revised: 05/02/2019] [Accepted: 05/07/2019] [Indexed: 11/13/2022] Open
Abstract
Stabilization of stalled replication forks prevents excessive fork reversal or degradation, which can undermine genome integrity. The WRN protein is unique among the other human RecQ family members to possess exonuclease activity. However, the biological role of the WRN exonuclease is poorly defined. Recently, the WRN exonuclease has been linked to protection of stalled forks from degradation. Alternative processing of perturbed forks has been associated to chemoresistance of BRCA-deficient cancer cells. Thus, we used WRN exonuclease-deficiency as a model to investigate the fate of perturbed forks undergoing degradation, but in a BRCA wild-type condition. We find that, upon treatment with clinically-relevant nanomolar doses of the Topoisomerase I inhibitor camptothecin, loss of WRN exonuclease stimulates fork inactivation and accumulation of parental gaps, which engages RAD51. Such mechanism affects reinforcement of CHK1 phosphorylation and causes persistence of RAD51 during recovery from treatment. Notably, in WRN exonuclease-deficient cells, persistence of RAD51 correlates with elevated mitotic phosphorylation of MUS81 at Ser87, which is essential to prevent excessive mitotic abnormalities. Altogether, these findings indicate that aberrant fork degradation, in the presence of a wild-type RAD51 axis, stimulates RAD51-mediated post-replicative repair and engagement of the MUS81 complex to limit genome instability and cell death.
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Affiliation(s)
- Francesca Antonella Aiello
- Mechanisms, Biomarkers and Models Unit, Department of Environment and Health, Istituto Superiore di Sanità, Roma, Italy
| | - Anita Palma
- Mechanisms, Biomarkers and Models Unit, Department of Environment and Health, Istituto Superiore di Sanità, Roma, Italy
| | - Eva Malacaria
- Mechanisms, Biomarkers and Models Unit, Department of Environment and Health, Istituto Superiore di Sanità, Roma, Italy
| | - Li Zheng
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, 1500 East Duarte Road, Duarte, CA 91010-3000, USA
| | - Judith L Campbell
- Braun Laboratories, California Institute of Technology, Pasadena, CA 91125, USA
| | - Binghui Shen
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute, City of Hope, 1500 East Duarte Road, Duarte, CA 91010-3000, USA
| | - Annapaola Franchitto
- Mechanisms, Biomarkers and Models Unit, Department of Environment and Health, Istituto Superiore di Sanità, Roma, Italy
| | - Pietro Pichierri
- Mechanisms, Biomarkers and Models Unit, Department of Environment and Health, Istituto Superiore di Sanità, Roma, Italy.,Istituto Nazionale Biostrutture e Biosistemi, Roma, Italy
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Marabitti V, Lillo G, Malacaria E, Palermo V, Sanchez M, Pichierri P, Franchitto A. ATM pathway activation limits R-loop-associated genomic instability in Werner syndrome cells. Nucleic Acids Res 2019; 47:3485-3502. [PMID: 30657978 PMCID: PMC6468170 DOI: 10.1093/nar/gkz025] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 01/08/2019] [Accepted: 01/11/2019] [Indexed: 01/22/2023] Open
Abstract
Werner syndrome (WS) is a cancer-prone disease caused by deficiency of Werner protein (WRN). WRN maintains genome integrity by promoting replication-fork stability after various forms of replication stress. Under mild replication stress, WS cells show impaired ATR-mediated CHK1 activation. However, it remains unclear if WS cells elicit other repair pathway. We demonstrate that loss of WRN leads to enhanced ATM phosphorylation upon prolonged exposure to aphidicolin, a specific inhibitor of DNA polymerases, resulting in CHK1 activation. Moreover, we find that loss of WRN sensitises cells to replication-transcription collisions and promotes accumulation of R-loops, which undergo XPG-dependent cleavage responsible for ATM signalling activation. Importantly, we observe that ATM pathway limits chromosomal instability in WS cells. Finally, we prove that, in WS cells, genomic instability enhanced upon chemical inhibition of ATM kinase activity is counteracted by direct or indirect suppression of R-loop formation or by XPG abrogation. Together, these findings suggest a potential role of WRN as regulator of R-loop-associated genomic instability, strengthening the notion that conflicts between replication and transcription can affect DNA replication, leading to human disease and cancer.
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Affiliation(s)
- Veronica Marabitti
- Department of Environment and Health, Section of Mechanisms Biomarkers and Models, Istituto Superiore di Sanita', Viale Regina Elena 299, Rome 00161, Italy
| | - Giorgia Lillo
- Department of Environment and Health, Section of Mechanisms Biomarkers and Models, Istituto Superiore di Sanita', Viale Regina Elena 299, Rome 00161, Italy
| | - Eva Malacaria
- Department of Environment and Health, Section of Mechanisms Biomarkers and Models, Istituto Superiore di Sanita', Viale Regina Elena 299, Rome 00161, Italy
| | - Valentina Palermo
- Department of Environment and Health, Section of Mechanisms Biomarkers and Models, Istituto Superiore di Sanita', Viale Regina Elena 299, Rome 00161, Italy
| | - Massimo Sanchez
- Department of Cell Biology and Neurosciences, Section of Gene and Cell Therapy, Istituto Superiore di Sanita', Viale Regina Elena 299, Rome 00161, Italy
| | - Pietro Pichierri
- Department of Environment and Health, Section of Mechanisms Biomarkers and Models, Istituto Superiore di Sanita', Viale Regina Elena 299, Rome 00161, Italy
| | - Annapaola Franchitto
- Department of Environment and Health, Section of Mechanisms Biomarkers and Models, Istituto Superiore di Sanita', Viale Regina Elena 299, Rome 00161, Italy
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Palma A, Pugliese GM, Murfuni I, Marabitti V, Malacaria E, Rinalducci S, Minoprio A, Sanchez M, Mazzei F, Zolla L, Franchitto A, Pichierri P. Phosphorylation by CK2 regulates MUS81/EME1 in mitosis and after replication stress. Nucleic Acids Res 2019; 46:5109-5124. [PMID: 29850896 PMCID: PMC6007509 DOI: 10.1093/nar/gky280] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Accepted: 04/04/2018] [Indexed: 12/21/2022] Open
Abstract
The MUS81 complex is crucial for preserving genome stability through the resolution of branched DNA intermediates in mitosis. However, untimely activation of the MUS81 complex in S-phase is dangerous. Little is known about the regulation of the human MUS81 complex and how deregulated activation affects chromosome integrity. Here, we show that the CK2 kinase phosphorylates MUS81 at Serine 87 in late-G2/mitosis, and upon mild replication stress. Phosphorylated MUS81 interacts with SLX4, and this association promotes the function of the MUS81 complex. In line with a role in mitosis, phosphorylation at Serine 87 is suppressed in S-phase and is mainly detected in the MUS81 molecules associated with EME1. Loss of CK2-dependent MUS81 phosphorylation contributes modestly to chromosome integrity, however, expression of the phosphomimic form induces DSBs accumulation in S-phase, because of unscheduled targeting of HJ-like DNA intermediates, and generates a wide chromosome instability phenotype. Collectively, our findings describe a novel regulatory mechanism controlling the MUS81 complex function in human cells. Furthermore, they indicate that, genome stability depends mainly on the ability of cells to counteract targeting of branched intermediates by the MUS81/EME1 complex in S-phase, rather than on a correct MUS81 function in mitosis.
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Affiliation(s)
- Anita Palma
- Mechanisms, Biomarkers and Models Unit, Department of Environment and Health, Istituto Superiore di Sanità - Viale Regina Elena 299, 00161 Rome, Italy
| | - Giusj Monia Pugliese
- Mechanisms, Biomarkers and Models Unit, Department of Environment and Health, Istituto Superiore di Sanità - Viale Regina Elena 299, 00161 Rome, Italy
| | - Ivana Murfuni
- Mechanisms, Biomarkers and Models Unit, Department of Environment and Health, Istituto Superiore di Sanità - Viale Regina Elena 299, 00161 Rome, Italy
| | - Veronica Marabitti
- Mechanisms, Biomarkers and Models Unit, Department of Environment and Health, Istituto Superiore di Sanità - Viale Regina Elena 299, 00161 Rome, Italy
| | - Eva Malacaria
- Mechanisms, Biomarkers and Models Unit, Department of Environment and Health, Istituto Superiore di Sanità - Viale Regina Elena 299, 00161 Rome, Italy
| | - Sara Rinalducci
- Proteomics, Metabolomics and Interactomics Lab, Department of Ecology and Biology, Università della Tuscia, Viale dell'Università snc, 01100 Viterbo, Italy
| | - Anna Minoprio
- Mechanisms, Biomarkers and Models Unit, Department of Environment and Health, Istituto Superiore di Sanità - Viale Regina Elena 299, 00161 Rome, Italy
| | - Massimo Sanchez
- Core Facilities Center - Section of Cytometry, Istituto Superiore di Sanità - Viale Regina Elena 299, 00161 Rome, Italy
| | - Filomena Mazzei
- Mechanisms, Biomarkers and Models Unit, Department of Environment and Health, Istituto Superiore di Sanità - Viale Regina Elena 299, 00161 Rome, Italy
| | - Lello Zolla
- Proteomics, Metabolomics and Interactomics Lab, Department of Ecology and Biology, Università della Tuscia, Viale dell'Università snc, 01100 Viterbo, Italy
| | - Annapaola Franchitto
- Mechanisms, Biomarkers and Models Unit, Department of Environment and Health, Istituto Superiore di Sanità - Viale Regina Elena 299, 00161 Rome, Italy
| | - Pietro Pichierri
- Mechanisms, Biomarkers and Models Unit, Department of Environment and Health, Istituto Superiore di Sanità - Viale Regina Elena 299, 00161 Rome, Italy
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Malacaria E, Pugliese GM, Honda M, Marabitti V, Aiello FA, Spies M, Franchitto A, Pichierri P. Author Correction: Rad52 prevents excessive replication fork reversal and protects from nascent strand degradation. Nat Commun 2019; 10:2023. [PMID: 31043602 PMCID: PMC6494817 DOI: 10.1038/s41467-019-10072-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Affiliation(s)
- Eva Malacaria
- Mechanisms, Biomarkers and Models Unit, Department of Environment and Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy
| | - Giusj Monia Pugliese
- Mechanisms, Biomarkers and Models Unit, Department of Environment and Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy
| | - Masayoshi Honda
- Department of Biochemistry, Carver College of Medicine, University of Iowa, 51 Newton Road 4-403 Bowen Science Building, Iowa City, IA, 52242, USA
| | - Veronica Marabitti
- Mechanisms, Biomarkers and Models Unit, Department of Environment and Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy
| | - Francesca Antonella Aiello
- Mechanisms, Biomarkers and Models Unit, Department of Environment and Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy
| | - Maria Spies
- Department of Biochemistry, Carver College of Medicine, University of Iowa, 51 Newton Road 4-403 Bowen Science Building, Iowa City, IA, 52242, USA
| | - Annapaola Franchitto
- Mechanisms, Biomarkers and Models Unit, Department of Environment and Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy
| | - Pietro Pichierri
- Mechanisms, Biomarkers and Models Unit, Department of Environment and Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy. .,Istituto Nazionale Biostrutture e Biosistemi, Viale delle Medaglie d'Oro, 305, 00136, Rome, Italy.
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Cortone G, Zheng G, Pensieri P, Chiappetta V, Tatè R, Malacaria E, Pichierri P, Yu H, Pisani FM. Interaction of the Warsaw breakage syndrome DNA helicase DDX11 with the replication fork-protection factor Timeless promotes sister chromatid cohesion. PLoS Genet 2018; 14:e1007622. [PMID: 30303954 PMCID: PMC6179184 DOI: 10.1371/journal.pgen.1007622] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Accepted: 08/13/2018] [Indexed: 12/19/2022] Open
Abstract
Establishment of sister chromatid cohesion is coupled to DNA replication, but the underlying molecular mechanisms are incompletely understood. DDX11 (also named ChlR1) is a super-family 2 Fe-S cluster-containing DNA helicase implicated in Warsaw breakage syndrome (WABS). Herein, we examined the role of DDX11 in cohesion establishment in human cells. We demonstrated that DDX11 interacts with Timeless, a component of the replication fork-protection complex, through a conserved peptide motif. The DDX11-Timeless interaction is critical for sister chromatid cohesion in interphase and mitosis. Immunofluorescence studies further revealed that cohesin association with chromatin requires DDX11. Finally, we demonstrated that DDX11 localises at nascent DNA by SIRF analysis. Moreover, we found that DDX11 promotes cohesin binding to the DNA replication forks in concert with Timeless and that recombinant purified cohesin interacts with DDX11 in vitro. Collectively, our results establish a critical role for the DDX11-Timeless interaction in coordinating DNA replication with sister chromatid cohesion, and have important implications for understanding the molecular basis of WABS.
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Affiliation(s)
- Giuseppe Cortone
- Istituto di Biochimica delle Proteine, Consiglio Nazionale Ricerche, Naples, Italy
| | - Ge Zheng
- Howard Hughes Medical Institute, Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
| | - Pasquale Pensieri
- Istituto di Biochimica delle Proteine, Consiglio Nazionale Ricerche, Naples, Italy
| | - Viviana Chiappetta
- Istituto di Biochimica delle Proteine, Consiglio Nazionale Ricerche, Naples, Italy
| | - Rosarita Tatè
- Istituto di Genetica e Biofisica "Adriano Buzzati Traverso", Consiglio Nazionale Ricerche, Naples, Italy
| | - Eva Malacaria
- Istituto Superiore di Sanità, Dipartimento Ambiente e Salute, Rome, Italy
| | - Pietro Pichierri
- Istituto Superiore di Sanità, Dipartimento Ambiente e Salute, Rome, Italy
| | - Hongtao Yu
- Howard Hughes Medical Institute, Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
- * E-mail: (HY); (FMP)
| | - Francesca M. Pisani
- Istituto di Biochimica delle Proteine, Consiglio Nazionale Ricerche, Naples, Italy
- * E-mail: (HY); (FMP)
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Malacaria E, Franchitto A, Pichierri P. SLX4 Prevents GEN1-Dependent DSBs During DNA Replication Arrest Under Pathological Conditions in Human Cells. Sci Rep 2017; 7:44464. [PMID: 28290553 PMCID: PMC5349550 DOI: 10.1038/srep44464] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Accepted: 02/08/2017] [Indexed: 01/06/2023] Open
Abstract
SLX4 is a versatile protein serving as docking for multiple structure-specific endonucleases during DNA repair, however, little is known about its function at demised replication forks. Using RNAi or FA-P cells complemented with SLX4 mutants that abrogate interaction with MUS81 or SLX1, we show that SLX4 cooperates with MUS81 to introduce DSBs after replication stress but also counteracts pathological targeting of demised forks by GEN1. Such unexpected function of SLX4 is unrelated to interaction with endonucleases, but concerns the physical presence of the protein. Strikingly, ectopic expression of the Holliday junction-binding protein RuvA inhibits DSBs in SLX4-deficient cells by preventing GEN1 chromatin-association, and rescues proliferation and genome integrity upon replication stress. Altogether, our results indicate that SLX4 is crucial to prevent accidental processing of Holliday junction-like intermediates at demised forks also suggesting that spontaneous genome instability in FA-P cells may derive, at least partially, from unscheduled action of GEN1 in S-phase.
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Affiliation(s)
- Eva Malacaria
- Section of Experimental and Computational Carcinogenesis, Department of Environment and Primary Prevention, Istituto Superiore di Sanità - Viale Regina Elena 299, 00161 Rome Italy
| | - Annapaola Franchitto
- Section of Molecular Epidemiology, Department of Environment and Primary Prevention, Istituto Superiore di Sanità - Viale Regina Elena 299, 00161 Rome Italy
| | - Pietro Pichierri
- Section of Experimental and Computational Carcinogenesis, Department of Environment and Primary Prevention, Istituto Superiore di Sanità - Viale Regina Elena 299, 00161 Rome Italy
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Hengel SR, Malacaria E, Folly da Silva Constantino L, Bain FE, Diaz A, Koch BG, Yu L, Wu M, Pichierri P, Spies MA, Spies M. Small-molecule inhibitors identify the RAD52-ssDNA interaction as critical for recovery from replication stress and for survival of BRCA2 deficient cells. eLife 2016; 5. [PMID: 27434671 PMCID: PMC4982760 DOI: 10.7554/elife.14740] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 07/18/2016] [Indexed: 12/20/2022] Open
Abstract
The DNA repair protein RAD52 is an emerging therapeutic target of high importance for BRCA-deficient tumors. Depletion of RAD52 is synthetically lethal with defects in tumor suppressors BRCA1, BRCA2 and PALB2. RAD52 also participates in the recovery of the stalled replication forks. Anticipating that ssDNA binding activity underlies the RAD52 cellular functions, we carried out a high throughput screening campaign to identify compounds that disrupt the RAD52-ssDNA interaction. Lead compounds were confirmed as RAD52 inhibitors in biochemical assays. Computational analysis predicted that these inhibitors bind within the ssDNA-binding groove of the RAD52 oligomeric ring. The nature of the inhibitor-RAD52 complex was validated through an in silico screening campaign, culminating in the discovery of an additional RAD52 inhibitor. Cellular studies with our inhibitors showed that the RAD52-ssDNA interaction enables its function at stalled replication forks, and that the inhibition of RAD52-ssDNA binding acts additively with BRCA2 or MUS81 depletion in cell killing. DOI:http://dx.doi.org/10.7554/eLife.14740.001 Cells are constantly in danger of losing or scrambling critical genetic information because of DNA damage. To cope with this stress, cells have numerous DNA repair systems. One of these systems – homology-directed DNA repair – involves the proteins BRCA1 and BRCA2, which are often missing or defective in breast and ovarian cancers. The BRCA-deficient cancer cells can still survive, but become “addicted” to other DNA repair proteins – among them a protein called RAD52. It might be possible to kill these cancer cells using drugs that stop RAD52 from working. Such treatments would have the benefit of not harming normal healthy cells, as these cells contain working BRCA proteins and can survive without RAD52. It is not currently known exactly how RAD52 allows the BRCA-deficient cells to survive, but this probably depends on RAD52’s ability to bind to single strands of DNA. Small molecules that block the interaction between the RAD52 protein and DNA might therefore help to kill cancer cells. Hengel et al. developed a high throughput biophysical method to search through a large collection of small molecules to find those that prevent RAD52 from binding to DNA. The best potential drug leads were then tested in laboratory-grown human cells and using biophysical and biochemical techniques. Computational approaches were also used to model how these molecules block the interaction between RAD52 and DNA at the atomistic level. Hengel et al. then used the information about how the small molecules bind to RAD52 to perform further computational screening. This identified a natural compound that competes with single-stranded DNA to bind to RAD52. The activity of this molecule was then validated using biophysical methods. The methods used by Hengel et al. provide the foundation for further searches for new anticancer drugs. Future studies that employ the small molecule drugs identified so far will also help to determine exactly how RAD52 works in human cells and how it helps cancer cells to survive. DOI:http://dx.doi.org/10.7554/eLife.14740.002
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Affiliation(s)
- Sarah R Hengel
- Department of Biochemistry, University of Iowa, Iowa City, United States
| | - Eva Malacaria
- Department of Environment and Health, Section of Experimental and Computational Carcinogenesis, Istituto Superiore di Sanita, Rome, Italy
| | - Laura Folly da Silva Constantino
- Division of Medicinal and Natural Products Chemistry, Department of Pharmaceutical Sciences and Experimental Therapeutics, University of Iowa, Iowa City, United States
| | - Fletcher E Bain
- Department of Biochemistry, University of Iowa, Iowa City, United States
| | - Andrea Diaz
- Department of Biochemistry, University of Iowa, Iowa City, United States
| | - Brandon G Koch
- Department of Biochemistry, University of Iowa, Iowa City, United States
| | - Liping Yu
- Department of Biochemistry, University of Iowa, Iowa City, United States.,NMR Core Facility, Carver College of Medicine, University of Iowa, Iowa City, United States
| | - Meng Wu
- Department of Biochemistry, University of Iowa, Iowa City, United States.,Division of Medicinal and Natural Products Chemistry, Department of Pharmaceutical Sciences and Experimental Therapeutics, University of Iowa, Iowa City, United States.,High Throughput Screening Facility, University of Iowa, Iowa City, United States
| | - Pietro Pichierri
- Department of Environment and Health, Section of Experimental and Computational Carcinogenesis, Istituto Superiore di Sanita, Rome, Italy
| | - M Ashley Spies
- Department of Biochemistry, University of Iowa, Iowa City, United States.,Division of Medicinal and Natural Products Chemistry, Department of Pharmaceutical Sciences and Experimental Therapeutics, University of Iowa, Iowa City, United States
| | - Maria Spies
- Department of Biochemistry, University of Iowa, Iowa City, United States
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