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Khayat F, Alshmery M, Pal M, Oliver A, Bianchi A. Binding of the TRF2 iDDR motif to RAD50 highlights a convergent evolutionary strategy to inactivate MRN at telomeres. Nucleic Acids Res 2024; 52:7704-7719. [PMID: 38884214 PMCID: PMC11260466 DOI: 10.1093/nar/gkae509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 05/07/2024] [Accepted: 06/07/2024] [Indexed: 06/18/2024] Open
Abstract
Telomeres protect chromosome ends from unscheduled DNA repair, including from the MRN (MRE11, RAD50, NBS1) complex, which processes double-stranded DNA breaks (DSBs) via activation of the ATM kinase, promotes DNA end-tethering aiding the non-homologous end-joining (NHEJ) pathway, and initiates DSB resection through the MRE11 nuclease. A protein motif (MIN, for MRN inhibitor) inhibits MRN at budding yeast telomeres by binding to RAD50 and evolved at least twice, in unrelated telomeric proteins Rif2 and Taz1. We identify the iDDR motif of human shelterin protein TRF2 as a third example of convergent evolution for this telomeric mechanism for binding MRN, despite the iDDR lacking sequence homology to the MIN motif. CtIP is required for activation of MRE11 nuclease action, and we provide evidence for binding of a short C-terminal region of CtIP to a RAD50 interface that partly overlaps with the iDDR binding site, indicating that the interaction is mutually exclusive. In addition, we show that the iDDR impairs the DNA binding activity of RAD50. These results highlight direct inhibition of MRN action as a crucial role of telomeric proteins across organisms and point to multiple mechanisms enforced by the iDDR to disable the many activities of the MRN complex.
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Affiliation(s)
- Freddy Khayat
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, UK
| | - Majedh Alshmery
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, UK
- Department of Life Sciences, Hafr Al Batin University, Saudi Arabia
| | - Mohinder Pal
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, UK
- School of Biosciences, University of Kent, Canterbury, UK
| | - Antony W Oliver
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, UK
| | - Alessandro Bianchi
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, UK
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2
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Nicolas Y, Bret H, Cannavo E, Acharya A, Cejka P, Borde V, Guerois R. Molecular insights into the activation of Mre11-Rad50 endonuclease activity by Sae2/CtIP. Mol Cell 2024; 84:2223-2237.e4. [PMID: 38870937 DOI: 10.1016/j.molcel.2024.05.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 02/25/2024] [Accepted: 05/20/2024] [Indexed: 06/15/2024]
Abstract
In Saccharomyces cerevisiae (S. cerevisiae), Mre11-Rad50-Xrs2 (MRX)-Sae2 nuclease activity is required for the resection of DNA breaks with secondary structures or protein blocks, while in humans, the MRE11-RAD50-NBS1 (MRN) homolog with CtIP is needed to initiate DNA end resection of all breaks. Phosphorylated Sae2/CtIP stimulates the endonuclease activity of MRX/N. Structural insights into the activation of the Mre11 nuclease are available only for organisms lacking Sae2/CtIP, so little is known about how Sae2/CtIP activates the nuclease ensemble. Here, we uncover the mechanism of Mre11 activation by Sae2 using a combination of AlphaFold2 structural modeling of biochemical and genetic assays. We show that Sae2 stabilizes the Mre11 nuclease in a conformation poised to cleave substrate DNA. Several designs of compensatory mutations establish how Sae2 activates MRX in vitro and in vivo, supporting the structural model. Finally, our study uncovers how human CtIP, despite considerable sequence divergence, employs a similar mechanism to activate MRN.
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Affiliation(s)
- Yoann Nicolas
- Institut Curie, PSL University, Sorbonne Université, CNRS UMR3244, Dynamics of Genetic Information, 75005 Paris, France
| | - Hélène Bret
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France
| | - Elda Cannavo
- Institute for Research in Biomedicine, Università della Svizzera italiana (USI), Faculty of Biomedical Sciences, Bellinzona 6500, Switzerland
| | - Ananya Acharya
- Institute for Research in Biomedicine, Università della Svizzera italiana (USI), Faculty of Biomedical Sciences, Bellinzona 6500, Switzerland
| | - Petr Cejka
- Institute for Research in Biomedicine, Università della Svizzera italiana (USI), Faculty of Biomedical Sciences, Bellinzona 6500, Switzerland.
| | - Valérie Borde
- Institut Curie, PSL University, Sorbonne Université, CNRS UMR3244, Dynamics of Genetic Information, 75005 Paris, France.
| | - Raphaël Guerois
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France.
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Zheng Y, Zhao Y, Dong K, Miao L, Zhou X, Gong Y, Zhang L. A novel Mre11 protein from the hyperthermophilic euryarchaeon Thermococcus barophilus Ch5 possesses 5'-3' exonuclease and endonuclease activities. Int J Biol Macromol 2024; 272:132654. [PMID: 38810854 DOI: 10.1016/j.ijbiomac.2024.132654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2024] [Revised: 05/21/2024] [Accepted: 05/23/2024] [Indexed: 05/31/2024]
Abstract
Mre11 is one of important proteins that are involved in DNA repair and recombination by processing DNA ends to produce 3'-single stranded DNA, thus providing a platform for other DNA repair and recombination proteins. In this work, we characterized the Mre11 protein from the hyperthermophilic euryarchaeon Thermococcus barophilus Ch5 (Tba-Mre11) biochemically and dissected the roles of its four conserved residues, which is the first report on Mre11 proteins from Thermococcus. Tba-Mre11 possesses exonuclease activity for degrading ssDNA and dsDNA in the 5'-3' direction, which contrasts with other reported Mre11 homologs. Maximum degradation efficiency was observed with Mn2+ at 80 °C and at pH 7.5-9.5. In addition to possessing 5'-3' exonuclease activity, Tba-Mre11 has endonuclease activity that nicks plasmid DNA and circular ssDNA. Mutational data show that residues D10, D51 and N86 in Tba-Mre11 are essential for DNA degradation since almost no activity was observed for the D10A, D51A and N86A mutants. By comparison, residue D44 in Tba-Mre11 is not responsible for DNA degradation since the D44A mutant possessed the similar WT protein activity. Notably, the D44A mutant almost completely abolished the ability to bind DNA, suggesting that residue D44 is essential for binding DNA.
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Affiliation(s)
- Yaqi Zheng
- College of Environmental Science and Engineering, Yangzhou University, China
| | - Yang Zhao
- College of Environmental Science and Engineering, Yangzhou University, China
| | - Kunming Dong
- College of Environmental Science and Engineering, Yangzhou University, China
| | - Li Miao
- College of Environmental Science and Engineering, Yangzhou University, China
| | - Xiaojian Zhou
- College of Environmental Science and Engineering, Yangzhou University, China
| | - Yong Gong
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, China
| | - Likui Zhang
- College of Environmental Science and Engineering, Yangzhou University, China.
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Qian W, Ye J, Xia S. DNA sensing of dendritic cells in cancer immunotherapy. Front Mol Biosci 2024; 11:1391046. [PMID: 38841190 PMCID: PMC11150630 DOI: 10.3389/fmolb.2024.1391046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2024] [Accepted: 05/02/2024] [Indexed: 06/07/2024] Open
Abstract
Dendritic cells (DCs) are involved in the initiation and maintenance of immune responses against malignant cells by recognizing conserved pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs) through pattern recognition receptors (PRRs). According to recent studies, tumor cell-derived DNA molecules act as DAMPs and are recognized by DNA sensors in DCs. Once identified by sensors in DCs, these DNA molecules trigger multiple signaling cascades to promote various cytokines secretion, including type I IFN, and then to induce DCs mediated antitumor immunity. As one of the potential attractive strategies for cancer therapy, various agonists targeting DNA sensors are extensively explored including the combination with other cancer immunotherapies or the direct usage as major components of cancer vaccines. Moreover, this review highlights different mechanisms through which tumor-derived DNA initiates DCs activation and the mechanisms through which the tumor microenvironment regulates DNA sensing of DCs to promote tumor immune escape. The contributions of chemotherapy, radiotherapy, and checkpoint inhibitors in tumor therapy to the DNA sensing of DCs are also discussed. Finally, recent clinical progress in tumor therapy utilizing agonist-targeted DNA sensors is summarized. Indeed, understanding more about DNA sensing in DCs will help to understand more about tumor immunotherapy and improve the efficacy of DC-targeted treatment in cancer.
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Affiliation(s)
- Wei Qian
- Department of Immunology, School of Medicine, Jiangsu University, Zhenjiang, Jiangsu, China
| | - Jun Ye
- Department of Immunology, School of Medicine, Jiangsu University, Zhenjiang, Jiangsu, China
- The Center for Translational Medicine, The Affiliated Taizhou People’s Hospital of Nanjing Medical University, Taizhou School of Clinical Medicine, Nanjing Medical University, Taizhou, Jiangsu, China
| | - Sheng Xia
- Department of Immunology, School of Medicine, Jiangsu University, Zhenjiang, Jiangsu, China
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Wang F, Yu X, Qian J, Cao Y, Dong S, Zhan S, Lu Z, Bast RC, Song Q, Chen Y, Zhang Y, Zhou J. A novel SIK2 inhibitor SIC-19 exhibits synthetic lethality with PARP inhibitors in ovarian cancer. Drug Resist Updat 2024; 74:101077. [PMID: 38518726 DOI: 10.1016/j.drup.2024.101077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Revised: 12/28/2023] [Accepted: 02/29/2024] [Indexed: 03/24/2024]
Abstract
PURPOSE Ovarian cancer patients with HR proficiency (HRP) have had limited benefits from PARP inhibitor treatment, highlighting the need for improved therapeutic strategies. In this study, we developed a novel SIK2 inhibitor, SIC-19, and investigated its potential to enhance the sensitivity and expand the clinical utility of PARP inhibitors in ovarian cancer. METHODS The SIK2 protein was modeled using a Molecular Operating Environment (MOE), and the most favorable model was selected based on a GBVI/WSA dG scoring function. The Chembridge Compound Library was screened, and the top 20 candidate compounds were tested for their interaction with SIK2 and downstream substrates, AKT-pS473 and MYLK-pS343. SIC-19 emerged as the most promising drug candidate and was further evaluated using multiple assays. RESULTS SIC-19 exhibited selective and potent inhibition of SIK2, leading to its degradation through the ubiquitination pathway. The IC50 of SIC-19 correlated inversely with endogenous SIK2 expression in ovarian cancer cell lines. Treatment with SIC-19 significantly inhibited cancer cell growth and sensitized cells to PARP inhibitors in vitro, as well as in ovarian cancer organoids and xenograft models. Mechanistically, SIK2 knockdown and SIC-19 treatment reduced RAD50 phosphorylation at Ser635, prevented nuclear translocation of RAD50, disrupted nuclear filament assembly, and impaired DNA homologous recombination repair, ultimately inducing apoptosis. These findings highlight the crucial role of SIK2 in the DNA HR repair pathway and demonstrate the significant PARP inhibitor sensitization achieved by SIC-19 in ovarian cancer. CONCLUSIONS SIC-19, a novel SIK2 inhibitor, effectively inhibits tumor cell growth in ovarian cancer by interfering with RAD50-mediated DNA HR repair. Furthermore, SIC-19 enhances the efficacy of PARP inhibitors, providing a promising therapeutic strategy to improve outcomes for ovarian cancer patients.
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Affiliation(s)
- Fang Wang
- Department of Obstetrics and Gynecology, The First Affiliated Hospital of Soochow University, Suzhou, China
| | - Xuejiao Yu
- Department of Imaging Department, The First Affiliated Hospital of Soochow University, Suzhou, China
| | - Jun Qian
- Department of Obstetrics and Gynecology, The First Affiliated Hospital of Soochow University, Suzhou, China
| | - Yumin Cao
- Department of Obstetrics and Gynecology, The First Affiliated Hospital of Soochow University, Suzhou, China
| | - Shunli Dong
- Department of Pharmacology, College of Pharmaceutical Sciences, Soochow University, Suzhou, China
| | - Shenghua Zhan
- Department of Pathology, The First Affiliated Hospital of Soochow University, Suzhou, China
| | - Zhen Lu
- Department of Experimental Therapeutics, University of Texas M.D. Anderson Cancer Center, Houston, TX, USA
| | - Robert C Bast
- Department of Experimental Therapeutics, University of Texas M.D. Anderson Cancer Center, Houston, TX, USA
| | - Qingxia Song
- Department of Obstetrics and Gynecology, Nanjing University of Chinese Medicine Affiliated Suzhou Hospital, Suzhou, China
| | - Youguo Chen
- Department of Obstetrics and Gynecology, The First Affiliated Hospital of Soochow University, Suzhou, China.
| | - Yi Zhang
- Department of Pharmacology, College of Pharmaceutical Sciences, Soochow University, Suzhou, China.
| | - Jinhua Zhou
- Department of Obstetrics and Gynecology, The First Affiliated Hospital of Soochow University, Suzhou, China.
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Roisné-Hamelin F, Liu HW, Taschner M, Li Y, Gruber S. Structural basis for plasmid restriction by SMC JET nuclease. Mol Cell 2024; 84:883-896.e7. [PMID: 38309275 DOI: 10.1016/j.molcel.2024.01.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Revised: 12/06/2023] [Accepted: 01/09/2024] [Indexed: 02/05/2024]
Abstract
DNA loop-extruding SMC complexes play crucial roles in chromosome folding and DNA immunity. Prokaryotic SMC Wadjet (JET) complexes limit the spread of plasmids through DNA cleavage, yet the mechanisms for plasmid recognition are unresolved. We show that artificial DNA circularization renders linear DNA susceptible to JET nuclease cleavage. Unlike free DNA, JET cleaves immobilized plasmid DNA at a specific site, the plasmid-anchoring point, showing that the anchor hinders DNA extrusion but not DNA cleavage. Structures of plasmid-bound JetABC reveal two presumably stalled SMC motor units that are drastically rearranged from the resting state, together entrapping a U-shaped DNA segment, which is further converted to kinked V-shaped cleavage substrate by JetD nuclease binding. Our findings uncover mechanical bending of residual unextruded DNA as molecular signature for plasmid recognition and non-self DNA elimination. We moreover elucidate key elements of SMC loop extrusion, including the motor direction and the structure of a DNA-holding state.
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Affiliation(s)
- Florian Roisné-Hamelin
- Department of Fundamental Microbiology (DMF), Faculty of Biology and Medicine (FBM), University of Lausanne (UNIL), 1015 Lausanne, Switzerland
| | - Hon Wing Liu
- Department of Fundamental Microbiology (DMF), Faculty of Biology and Medicine (FBM), University of Lausanne (UNIL), 1015 Lausanne, Switzerland
| | - Michael Taschner
- Department of Fundamental Microbiology (DMF), Faculty of Biology and Medicine (FBM), University of Lausanne (UNIL), 1015 Lausanne, Switzerland
| | - Yan Li
- Department of Fundamental Microbiology (DMF), Faculty of Biology and Medicine (FBM), University of Lausanne (UNIL), 1015 Lausanne, Switzerland
| | - Stephan Gruber
- Department of Fundamental Microbiology (DMF), Faculty of Biology and Medicine (FBM), University of Lausanne (UNIL), 1015 Lausanne, Switzerland.
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Roisné-Hamelin F, Marcand S. All roads lead to MRN regulation at telomeres: different paths to one solution. Nat Struct Mol Biol 2023; 30:1242-1243. [PMID: 37653240 DOI: 10.1038/s41594-023-01077-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
Affiliation(s)
- Florian Roisné-Hamelin
- Department of Fundamental Microbiology (DMF), Faculty of Biology and Medicine (FBM), University of Lausanne (UNIL), Lausanne, Switzerland
| | - Stéphane Marcand
- Université Paris-Saclay, Université Paris-Cité, Inserm, CEA, Institut de Biologie François Jacob, iRCM, UMR Stabilité Génétique Cellules Souches et Radiations, Fontenay-aux-Roses, France.
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Bruserud Ø, Reikvam H. Casein Kinase 2 (CK2): A Possible Therapeutic Target in Acute Myeloid Leukemia. Cancers (Basel) 2023; 15:3711. [PMID: 37509370 PMCID: PMC10378128 DOI: 10.3390/cancers15143711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2023] [Revised: 07/14/2023] [Accepted: 07/20/2023] [Indexed: 07/30/2023] Open
Abstract
The protein kinase CK2 (also known as casein kinase 2) is one of the main contributors to the human phosphoproteome. It is regarded as a possible therapeutic strategy in several malignant diseases, including acute myeloid leukemia (AML), which is an aggressive bone marrow malignancy. CK2 is an important regulator of intracellular signaling in AML cells, especially PI3K-Akt, Jak-Stat, NFκB, Wnt, and DNA repair signaling. High CK2 levels in AML cells at the first time of diagnosis are associated with decreased survival (i.e., increased risk of chemoresistant leukemia relapse) for patients receiving intensive and potentially curative antileukemic therapy. However, it is not known whether these high CK2 levels can be used as an independent prognostic biomarker because this has not been investigated in multivariate analyses. Several CK2 inhibitors have been developed, but CX-4945/silmitasertib is best characterized. This drug has antiproliferative and proapoptotic effects in primary human AML cells. The preliminary results from studies of silmitasertib in the treatment of other malignancies suggest that gastrointestinal and bone marrow toxicities are relatively common. However, clinical AML studies are not available. Taken together, the available experimental and clinical evidence suggests that the possible use of CK2 inhibition in the treatment of AML should be further investigated.
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Affiliation(s)
- Øystein Bruserud
- Institute for Clinical Science, Faculty of Medicine, University of Bergen, 5021 Bergen, Norway
- Section for Hematology, Department of Medicine, Haukeland University Hospital, 5021 Bergen, Norway
| | - Håkon Reikvam
- Institute for Clinical Science, Faculty of Medicine, University of Bergen, 5021 Bergen, Norway
- Section for Hematology, Department of Medicine, Haukeland University Hospital, 5021 Bergen, Norway
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