1
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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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Pizzul P, Casari E, Rinaldi C, Gnugnoli M, Mangiagalli M, Tisi R, Longhese MP. Rif2 interaction with Rad50 counteracts Tel1 functions in checkpoint signalling and DNA tethering by releasing Tel1 from MRX binding. Nucleic Acids Res 2024; 52:2355-2371. [PMID: 38180815 PMCID: PMC10954470 DOI: 10.1093/nar/gkad1246] [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: 07/15/2023] [Revised: 12/14/2023] [Accepted: 12/18/2023] [Indexed: 01/07/2024] Open
Abstract
The yeast Rif2 protein is known to inhibit Mre11 nuclease and the activation of Tel1 kinase through a short motif termed MIN, which binds the Rad50 subunit and simulates its ATPase activity in vitro. The mechanism by which Rif2 restrains Tel1 activation and the consequences of this inhibition at DNA double-strand breaks (DSBs) are poorly understood. In this study, we employed AlphaFold-Multimer modelling to pinpoint and validate the interaction surface between Rif2 MIN and Rad50. We also engineered the rif2-S6E mutation that enhances the inhibitory effect of Rif2 by increasing Rif2-Rad50 interaction. Unlike rif2Δ, the rif2-S6E mutation impairs hairpin cleavage. Furthermore, it diminishes Tel1 activation by inhibiting Tel1 binding to DSBs while leaving MRX association unchanged, indicating that Rif2 can directly inhibit Tel1 recruitment to DSBs. Additionally, Rif2S6E reduces Tel1-MRX interaction and increases stimulation of ATPase by Rad50, indicating that Rif2 binding to Rad50 induces an ADP-bound MRX conformation that is not suitable for Tel1 binding. The decreased Tel1 recruitment to DSBs in rif2-S6E cells impairs DSB end-tethering and this bridging defect is suppressed by expressing a Tel1 mutant variant that increases Tel1 persistence at DSBs, suggesting a direct role for Tel1 in the bridging of DSB ends.
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Affiliation(s)
- Paolo Pizzul
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano - Bicocca, 20126 Milano, Italy
| | - Erika Casari
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano - Bicocca, 20126 Milano, Italy
| | - Carlo Rinaldi
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano - Bicocca, 20126 Milano, Italy
| | - Marco Gnugnoli
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano - Bicocca, 20126 Milano, Italy
| | - Marco Mangiagalli
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano - Bicocca, 20126 Milano, Italy
| | - Renata Tisi
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano - Bicocca, 20126 Milano, Italy
| | - Maria Pia Longhese
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano - Bicocca, 20126 Milano, Italy
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3
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Cho MG, Kumar RJ, Lin CC, Boyer JA, Shahir JA, Fagan-Solis K, Simpson DA, Fan C, Foster CE, Goddard AM, Lerner LM, Ellington SW, Wang Q, Wang Y, Ho AY, Liu P, Perou CM, Zhang Q, McGinty RK, Purvis JE, Gupta GP. MRE11 liberates cGAS from nucleosome sequestration during tumorigenesis. Nature 2024; 625:585-592. [PMID: 38200309 PMCID: PMC10794148 DOI: 10.1038/s41586-023-06889-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 11/22/2023] [Indexed: 01/12/2024]
Abstract
Oncogene-induced replication stress generates endogenous DNA damage that activates cGAS-STING-mediated signalling and tumour suppression1-3. However, the precise mechanism of cGAS activation by endogenous DNA damage remains enigmatic, particularly given that high-affinity histone acidic patch (AP) binding constitutively inhibits cGAS by sterically hindering its activation by double-stranded DNA (dsDNA)4-10. Here we report that the DNA double-strand break sensor MRE11 suppresses mammary tumorigenesis through a pivotal role in regulating cGAS activation. We demonstrate that binding of the MRE11-RAD50-NBN complex to nucleosome fragments is necessary to displace cGAS from acidic-patch-mediated sequestration, which enables its mobilization and activation by dsDNA. MRE11 is therefore essential for cGAS activation in response to oncogenic stress, cytosolic dsDNA and ionizing radiation. Furthermore, MRE11-dependent cGAS activation promotes ZBP1-RIPK3-MLKL-mediated necroptosis, which is essential to suppress oncogenic proliferation and breast tumorigenesis. Notably, downregulation of ZBP1 in human triple-negative breast cancer is associated with increased genome instability, immune suppression and poor patient prognosis. These findings establish MRE11 as a crucial mediator that links DNA damage and cGAS activation, resulting in tumour suppression through ZBP1-dependent necroptosis.
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Affiliation(s)
- Min-Guk Cho
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Rashmi J Kumar
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- UNC MD-PhD Program, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA
| | - Chien-Chu Lin
- Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Joshua A Boyer
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Jamshaid A Shahir
- Curriculum in Bioinformatics and Computational Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Katerina Fagan-Solis
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Dennis A Simpson
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Cheng Fan
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Christine E Foster
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Anna M Goddard
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Lynn M Lerner
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Simon W Ellington
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Qinhong Wang
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Ying Wang
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Alice Y Ho
- Department of Radiation Oncology, Massachusetts General Hospital, Boston, MA, USA
| | - Pengda Liu
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Charles M Perou
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Computational Medicine Program, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Qi Zhang
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Robert K McGinty
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Jeremy E Purvis
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Computational Medicine Program, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Gaorav P Gupta
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
- UNC MD-PhD Program, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA.
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
- Department of Radiation Oncology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
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4
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Behl T, Kumar A, Vishakha, Sehgal A, Singh S, Sharma N, Yadav S, Rashid S, Ali N, Ahmed AS, Vargas-De-La-Cruz C, Bungau SG, Khan H. Understanding the mechanistic pathways and clinical aspects associated with protein and gene based biomarkers in breast cancer. Int J Biol Macromol 2023; 253:126595. [PMID: 37648139 DOI: 10.1016/j.ijbiomac.2023.126595] [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: 05/02/2023] [Revised: 08/22/2023] [Accepted: 08/27/2023] [Indexed: 09/01/2023]
Abstract
Cancer is one of the most widespread and severe diseases with a huge mortality rate. In recent years, the second-leading mortality rate of any cancer globally has been breast cancer, which is one of the most common and deadly cancers found in women. Detecting breast cancer in its initial stages simplifies treatment, decreases death risk, and recovers survival rates for patients. The death rate for breast cancer has risen to 0.024 % in some regions. Sensitive and accurate technologies are required for the preclinical detection of BC at an initial stage. Biomarkers play a very crucial role in the early identification as well as diagnosis of women with breast cancer. Currently, a wide variety of cancer biomarkers have been discovered for the diagnosis of cancer. For the identification of these biomarkers from serum or other body fluids at physiological amounts, many detection methods have been developed. In the case of breast cancer, biomarkers are especially helpful in discovering those who are more likely to develop the disease, determining prognosis at the time of initial diagnosis and choosing the best systemic therapy. In this study we have compiled various clinical aspects and signaling pathways associated with protein-based biomarkers and gene-based biomarkers.
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Affiliation(s)
- Tapan Behl
- School of Health Sciences and Technology, University of Petroleum and Energy Studies, Dehradun 248007, Uttarakhand, India
| | - Ankush Kumar
- Institute of Pharmaceutical Sciences, IET Bhaddal Technical Campus, Ropar 140108, Punjab, India
| | - Vishakha
- Institute of Pharmaceutical Sciences, IET Bhaddal Technical Campus, Ropar 140108, Punjab, India
| | - Aayush Sehgal
- GHG Khalsa College of Pharmacy, Gurusar Sadhar, 141104 Ludhiana, Punjab, India
| | - Sukhbir Singh
- Department of Pharmaceutics, MM College of Pharmacy, Maharishi Markandeshwar (Deemed to be University), Mullana Ambala 133203, Haryana, India
| | - Neelam Sharma
- Department of Pharmaceutics, MM College of Pharmacy, Maharishi Markandeshwar (Deemed to be University), Mullana Ambala 133203, Haryana, India
| | - Shivam Yadav
- School of Pharmacy, Babu Banarasi Das University, Lucknow 226028, Uttar Pradesh, India
| | - Summya Rashid
- Department of Pharmacology and Toxicology, College of Pharmacy, Prince Sattam Bin Abdulaziz University, P.O. Box 173, Al-Kharj 11942, Saudi Arabia.
| | - Nemat Ali
- Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, P.O. Box 2457, Riyadah 11451, Saudi Arabia
| | - Amira Saber Ahmed
- Hormones Department, Medical Research and Clinical Studies Institute, National Research Centre, Giza 12622, Egypt
| | - Celia Vargas-De-La-Cruz
- Department of Pharmacology, Bromatology and Toxicology, Faculty of Pharmacy and Biochemistry, Universidad Nacional Mayor de San Marcos, Lima 150001, Peru; E-Health Research Center, Universidad de Ciencias y Humanidades, Lima 15001, Peru
| | - Simona Gabriela Bungau
- Department of Pharmacy, Faculty of Medicine and Pharmacy, University of Oradea, Oradea 410087, Romania; Doctoral School of Biomedical Sciences, University of Oradea, Oradea 410087, Romania
| | - Haroon Khan
- Department of Pharmacy, Abdul Wali Khan University, Mardan 23200, Pakistan.
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5
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Bajek A, Przewodowska D, Koziorowski D, Jędrzejowska M, Szlufik S. Cervical dystonia and no oculomotor apraxia as new manifestation of ataxia-telangiectasia-like disorder 1 - case report and review of the literature. Front Neurol 2023; 14:1243535. [PMID: 37808486 PMCID: PMC10556495 DOI: 10.3389/fneur.2023.1243535] [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: 06/20/2023] [Accepted: 09/06/2023] [Indexed: 10/10/2023] Open
Abstract
Ataxia-telangiectasia-like disorder 1 (ATLD1) is a rare neurodegenerative disorder associated with early onset ataxia and oculomotor apraxia. The genetic determination of ATLD1 is a mutation in the MRE11 gene (meiotic recombination 11 gene), which causes DNA-double strand break repair deficits. Clinical features of patients with ATLD1 resemble those of ataxia telangiectasia (AT), with slower progression and milder presentation. Main symptoms include progressive cerebellar ataxia, oculomotor apraxia, cellular hypersensitivity to ionizing radiations. Facial dyskinesia, dystonia, dysarthria have also been reported. Here we present a 45-year old woman with cervical and facial dystonia, dysarthria and ataxia, who turned out to be the first case of ATLD without oculomotor apraxia, and with dystonia as a main manifestation of the disease. She had presented those non-specific symptoms for years, before whole exome sequencing confirmed the diagnosis.
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Affiliation(s)
- Agnieszka Bajek
- Department of Neurology, Faculty of Health Sciences, Medical University of Warsaw, Warsaw, Poland
| | - Dominika Przewodowska
- Department of Neurology, Faculty of Health Sciences, Medical University of Warsaw, Warsaw, Poland
| | - Dariusz Koziorowski
- Department of Neurology, Faculty of Health Sciences, Medical University of Warsaw, Warsaw, Poland
| | - Maria Jędrzejowska
- Genomed Health Care Center, Warsaw, Poland
- Department of Neurology, Medical University of Warsaw, Warsaw, Poland
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6
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Ayala-Zambrano C, Yuste M, Frias S, Garcia-de-Teresa B, Mendoza L, Azpeitia E, Rodríguez A, Torres L. A Boolean network model of the double-strand break repair pathway choice. J Theor Biol 2023; 573:111608. [PMID: 37595867 DOI: 10.1016/j.jtbi.2023.111608] [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: 04/11/2023] [Revised: 07/29/2023] [Accepted: 08/09/2023] [Indexed: 08/20/2023]
Abstract
Double strand break (DSB) repair is critical to maintaining the integrity of the genome. DSB repair deficiency underlies multiple pathologies, including cancer, chromosome instability syndromes, and, potentially, neurodevelopmental defects. DSB repair is mainly handled by two pathways: highly accurate homologous recombination (HR), which requires a sister chromatid for template-based repair, limited to S/G2 phases of the cell cycle, and canonical non-homologous end joining (c-NHEJ), available throughout the cell cycle in which minimum homology is sufficient for highly efficient yet error-prone repair. Some circumstances, such as cancer, require alternative highly mutagenic DSB repair pathways like microhomology-mediated end-joining (MMEJ) and single-strand annealing (SSA), which are triggered to attend to DNA damage. These non-canonical repair alternatives are emerging as prominent drivers of resistance in drug-based tumor therapies. Multiple DSB repair options require tight inter-pathway regulation to prevent unscheduled activities. In addition to this complexity, epigenetic modifications of the histones surrounding the DSB region are emerging as critical regulators of the DSB repair pathway choice. Modeling approaches to understanding DSBs repair pathway choice are advantageous to perform simulations and generate predictions on previously uncharacterized aspects of DSBs response. In this work, we present a Boolean network model of the DSB repair pathway choice that incorporates the knowledge, into a dynamic system, of the inter-pathways regulation involved in DSB repair, i.e., HR, c-NHEJ, SSA, and MMEJ. Our model recapitulates the well-characterized HR activity observed in wild-type cells in response to DSBs. It also recovers clinically relevant behaviors of BRCA1/FANCS mutants, and their corresponding drug resistance mechanisms ascribed to DNA repair gain-of-function pathogenic variants. Since epigenetic modifiers are dynamic and possible druggable targets, we incorporated them into our model to better characterize their involvement in DSB repair. Our model predicted that loss of the TIP60 complex and its corresponding histone acetylation activity leads to activation of SSA in response to DSBs. Our experimental validation showed that TIP60 effectively prevents activation of RAD52, a key SSA executor, and confirms the suitable use of Boolean network modeling for understanding DNA DSB repair.
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Affiliation(s)
- Cecilia Ayala-Zambrano
- Laboratorio de Citogenética, Instituto Nacional de Pediatría, Ciudad de México 04530, Mexico; Posgrado en Ciencias Biológicas, Universidad Nacional Autónoma de México, Ciudad de México 04510, Mexico
| | - Mariana Yuste
- Centro de Ciencias Matemáticas, Universidad Nacional Autónoma de México, Morelia, Mexico
| | - Sara Frias
- Laboratorio de Citogenética, Instituto Nacional de Pediatría, Ciudad de México 04530, Mexico; Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Apartado Postal 70228, Ciudad de México 04510, Mexico
| | | | - Luis Mendoza
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Apartado Postal 70228, Ciudad de México 04510, Mexico
| | - Eugenio Azpeitia
- Centro de Ciencias Matemáticas, Universidad Nacional Autónoma de México, Morelia, Mexico
| | - Alfredo Rodríguez
- Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Apartado Postal 70228, Ciudad de México 04510, Mexico; Instituto Nacional de Pediatría, Ciudad de México 04530, Mexico.
| | - Leda Torres
- Laboratorio de Citogenética, Instituto Nacional de Pediatría, Ciudad de México 04530, Mexico.
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7
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Torres-Montaner A. Interactions between the DNA Damage Response and the Telomere Complex in Carcinogenesis: A Hypothesis. Curr Issues Mol Biol 2023; 45:7582-7616. [PMID: 37754262 PMCID: PMC10527771 DOI: 10.3390/cimb45090478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 09/12/2023] [Accepted: 09/14/2023] [Indexed: 09/28/2023] Open
Abstract
Contrary to what was once thought, direct cancer originating from normal stem cells seems to be extremely rare. This is consistent with a preneoplastic period of telomere length reduction/damage in committed cells that becomes stabilized in transformation. Multiple observations suggest that telomere damage is an obligatory step preceding its stabilization. During tissue turnover, the telomeres of cells undergoing differentiation can be damaged as a consequence of defective DNA repair caused by endogenous or exogenous agents. This may result in the emergence of new mechanism of telomere maintenance which is the final outcome of DNA damage and the initial signal that triggers malignant transformation. Instead, transformation of stem cells is directly induced by primary derangement of telomere maintenance mechanisms. The newly modified telomere complex may promote survival of cancer stem cells, independently of telomere maintenance. An inherent resistance of stem cells to transformation may be linked to specific, robust mechanisms that help maintain telomere integrity.
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Affiliation(s)
- Antonio Torres-Montaner
- Department of Pathology, Queen’s Hospital, Rom Valley Way, Romford, London RM7 OAG, UK;
- Departamento de Bioquímica y Biologia Molecular, Universidad de Cadiz, Puerto Real, 11510 Cadiz, Spain
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8
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Sun JKL, Wong GCN, Chow KHM. Cross-talk between DNA damage response and the central carbon metabolic network underlies selective vulnerability of Purkinje neurons in ataxia-telangiectasia. J Neurochem 2023; 166:654-677. [PMID: 37319113 DOI: 10.1111/jnc.15881] [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: 04/30/2023] [Revised: 05/30/2023] [Accepted: 06/01/2023] [Indexed: 06/17/2023]
Abstract
Cerebellar ataxia is often the first and irreversible outcome in the disease of ataxia-telangiectasia (A-T), as a consequence of selective cerebellar Purkinje neuronal degeneration. A-T is an autosomal recessive disorder resulting from the loss-of-function mutations of the ataxia-telangiectasia-mutated ATM gene. Over years of research, it now becomes clear that functional ATM-a serine/threonine kinase protein product of the ATM gene-plays critical roles in regulating both cellular DNA damage response and central carbon metabolic network in multiple subcellular locations. The key question arises is how cerebellar Purkinje neurons become selectively vulnerable when all other cell types in the brain are suffering from the very same defects in ATM function. This review intended to comprehensively elaborate the unexpected linkages between these two seemingly independent cellular functions and the regulatory roles of ATM involved, their integrated impacts on both physical and functional properties, hence the introduction of selective vulnerability to Purkinje neurons in the disease will be addressed.
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Affiliation(s)
- Jacquelyne Ka-Li Sun
- School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Hong Kong
| | - Genper Chi-Ngai Wong
- School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Hong Kong
| | - Kim Hei-Man Chow
- School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Hong Kong
- Gerald Choa Neuroscience Institute, The Chinese University of Hong Kong, Hong Kong
- Nexus of Rare Neurodegenerative Diseases, The Chinese University of Hong Kong, Hong Kong
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9
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Viner-Breuer R, Golan-Lev T, Benvenisty N, Goldberg M. Genome-Wide Screening in Human Embryonic Stem Cells Highlights the Hippo Signaling Pathway as Granting Synthetic Viability in ATM Deficiency. Cells 2023; 12:1503. [PMID: 37296624 PMCID: PMC10253227 DOI: 10.3390/cells12111503] [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: 04/27/2023] [Revised: 05/18/2023] [Accepted: 05/26/2023] [Indexed: 06/12/2023] Open
Abstract
ATM depletion is associated with the multisystemic neurodegenerative syndrome ataxia-telangiectasia (A-T). The exact linkage between neurodegeneration and ATM deficiency has not been established yet, and no treatment is currently available. In this study, we aimed to identify synthetic viable genes in ATM deficiency to highlight potential targets for the treatment of neurodegeneration in A-T. We inhibited ATM kinase activity using the background of a genome-wide haploid pluripotent CRISPR/Cas9 loss-of-function library and examined which mutations confer a growth advantage on ATM-deficient cells specifically. Pathway enrichment analysis of the results revealed the Hippo signaling pathway as a major negative regulator of cellular growth upon ATM inhibition. Indeed, genetic perturbation of the Hippo pathway genes SAV1 and NF2, as well as chemical inhibition of this pathway, specifically promoted the growth of ATM-knockout cells. This effect was demonstrated in both human embryonic stem cells and neural progenitor cells. Therefore, we suggest the Hippo pathway as a candidate target for the treatment of the devastating cerebellar atrophy associated with A-T. In addition to the Hippo pathway, our work points out additional genes, such as the apoptotic regulator BAG6, as synthetic viable with ATM-deficiency. These genes may help to develop drugs for the treatment of A-T patients as well as to define biomarkers for resistance to ATM inhibition-based chemotherapies and to gain new insights into the ATM genetic network.
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Affiliation(s)
- Ruth Viner-Breuer
- The Azrieli Center for Stem Cells and Genetic Research, The Hebrew University, Givat-Ram, Jerusalem 9190401, Israel; (R.V.-B.); (T.G.-L.)
- Department of Genetics, Institute of Life Sciences, The Hebrew University, Givat-Ram, Jerusalem 9190401, Israel
| | - Tamar Golan-Lev
- The Azrieli Center for Stem Cells and Genetic Research, The Hebrew University, Givat-Ram, Jerusalem 9190401, Israel; (R.V.-B.); (T.G.-L.)
- Department of Genetics, Institute of Life Sciences, The Hebrew University, Givat-Ram, Jerusalem 9190401, Israel
| | - Nissim Benvenisty
- The Azrieli Center for Stem Cells and Genetic Research, The Hebrew University, Givat-Ram, Jerusalem 9190401, Israel; (R.V.-B.); (T.G.-L.)
- Department of Genetics, Institute of Life Sciences, The Hebrew University, Givat-Ram, Jerusalem 9190401, Israel
| | - Michal Goldberg
- Department of Genetics, Institute of Life Sciences, The Hebrew University, Givat-Ram, Jerusalem 9190401, Israel
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10
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Post-Transcriptional and Post-Translational Modifications in Telomerase Biogenesis and Recruitment to Telomeres. Int J Mol Sci 2023; 24:ijms24055027. [PMID: 36902458 PMCID: PMC10003056 DOI: 10.3390/ijms24055027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 03/02/2023] [Accepted: 03/03/2023] [Indexed: 03/08/2023] Open
Abstract
Telomere length is associated with the proliferative potential of cells. Telomerase is an enzyme that elongates telomeres throughout the entire lifespan of an organism in stem cells, germ cells, and cells of constantly renewed tissues. It is activated during cellular division, including regeneration and immune responses. The biogenesis of telomerase components and their assembly and functional localization to the telomere is a complex system regulated at multiple levels, where each step must be tuned to the cellular requirements. Any defect in the function or localization of the components of the telomerase biogenesis and functional system will affect the maintenance of telomere length, which is critical to the processes of regeneration, immune response, embryonic development, and cancer progression. An understanding of the regulatory mechanisms of telomerase biogenesis and activity is necessary for the development of approaches toward manipulating telomerase to influence these processes. The present review focuses on the molecular mechanisms involved in the major steps of telomerase regulation and the role of post-transcriptional and post-translational modifications in telomerase biogenesis and function in yeast and vertebrates.
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Rotheneder M, Stakyte K, van de Logt E, Bartho JD, Lammens K, Fan Y, Alt A, Kessler B, Jung C, Roos WP, Steigenberger B, Hopfner KP. Cryo-EM structure of the Mre11-Rad50-Nbs1 complex reveals the molecular mechanism of scaffolding functions. Mol Cell 2023; 83:167-185.e9. [PMID: 36577401 DOI: 10.1016/j.molcel.2022.12.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 10/14/2022] [Accepted: 12/03/2022] [Indexed: 12/28/2022]
Abstract
The DNA double-strand break repair complex Mre11-Rad50-Nbs1 (MRN) detects and nucleolytically processes DNA ends, activates the ATM kinase, and tethers DNA at break sites. How MRN can act both as nuclease and scaffold protein is not well understood. The cryo-EM structure of MRN from Chaetomium thermophilum reveals a 2:2:1 complex with a single Nbs1 wrapping around the autoinhibited Mre11 nuclease dimer. MRN has two DNA-binding modes, one ATP-dependent mode for loading onto DNA ends and one ATP-independent mode through Mre11's C terminus, suggesting how it may interact with DSBs and intact DNA. MRNs two 60-nm-long coiled-coil domains form a linear rod structure, the apex of which is assembled by the two joined zinc-hook motifs. Apices from two MRN complexes can further dimerize, forming 120-nm spanning MRN-MRN structures. Our results illustrate the architecture of MRN and suggest how it mechanistically integrates catalytic and tethering functions.
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Affiliation(s)
- Matthias Rotheneder
- Gene Center, Department of Biochemistry, Ludwig Maximilians Universität, Munich, Germany
| | - Kristina Stakyte
- Gene Center, Department of Biochemistry, Ludwig Maximilians Universität, Munich, Germany
| | - Erik van de Logt
- Gene Center, Department of Biochemistry, Ludwig Maximilians Universität, Munich, Germany
| | - Joseph D Bartho
- Gene Center, Department of Biochemistry, Ludwig Maximilians Universität, Munich, Germany
| | - Katja Lammens
- Gene Center, Department of Biochemistry, Ludwig Maximilians Universität, Munich, Germany
| | - Yilan Fan
- Gene Center, Department of Biochemistry, Ludwig Maximilians Universität, Munich, Germany
| | - Aaron Alt
- Gene Center, Department of Biochemistry, Ludwig Maximilians Universität, Munich, Germany
| | - Brigitte Kessler
- Gene Center, Department of Biochemistry, Ludwig Maximilians Universität, Munich, Germany
| | - Christophe Jung
- Gene Center, Department of Biochemistry, Ludwig Maximilians Universität, Munich, Germany
| | - Wynand P Roos
- Institute for Toxicology, Johannes-Gutenberg-Universität, Mainz, Germany
| | - Barbara Steigenberger
- Mass Spectrometry Core Facility, Max-Planck-Institute of Biochemistry, Martinsried, Germany
| | - Karl-Peter Hopfner
- Gene Center, Department of Biochemistry, Ludwig Maximilians Universität, Munich, Germany.
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12
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TRIP13 Participates in Immediate-Early Sensing of DNA Strand Breaks and ATM Signaling Amplification through MRE11. Cells 2022; 11:cells11244095. [PMID: 36552858 PMCID: PMC9776959 DOI: 10.3390/cells11244095] [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: 10/23/2022] [Revised: 12/07/2022] [Accepted: 12/09/2022] [Indexed: 12/24/2022] Open
Abstract
Thyroid hormone receptor-interacting protein 13 (TRIP13) participates in various regulatory steps related to the cell cycle, such as the mitotic spindle assembly checkpoint and meiotic recombination, possibly by interacting with members of the HORMA domain protein family. Recently, it was reported that TRIP13 could regulate the choice of the DNA repair pathway, i.e., homologous recombination (HR) or nonhomologous end-joining (NHEJ). However, TRIP13 is recruited to DNA damage sites within a few seconds after damage and may therefore have another function in DNA repair other than regulation of the pathway choice. Furthermore, the depletion of TRIP13 inhibited both HR and NHEJ, suggesting that TRIP13 plays other roles besides regulation of choice between HR and NHEJ. To explore the unidentified functions of TRIP13 in the DNA damage response, we investigated its genome-wide interaction partners in the context of DNA damage using quantitative proteomics with proximity labeling. We identified MRE11 as a novel interacting partner of TRIP13. TRIP13 controlled the recruitment of MDC1 to DNA damage sites by regulating the interaction between MDC1 and the MRN complex. Consistently, TRIP13 was involved in ATM signaling amplification. Our study provides new insight into the function of TRIP13 in immediate-early DNA damage sensing and ATM signaling activation.
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13
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Łuczkowski M, Padjasek M, Ba Tran J, Hemmingsen L, Kerber O, Habjanič J, Freisinger E, Krężel A. An Extremely Stable Interprotein Tetrahedral Hg(Cys) 4 Core Forms in the Zinc Hook Domain of Rad50 Protein at Physiological pH. Chemistry 2022; 28:e202202738. [PMID: 36222310 PMCID: PMC9828754 DOI: 10.1002/chem.202202738] [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: 09/01/2022] [Indexed: 11/09/2022]
Abstract
In nature, thiolate-based systems are the primary targets of divalent mercury (HgII ) toxicity. The formation of Hg(Cys)x cores in catalytic and structural protein centers mediates mercury's toxic effects and ultimately leads to cellular damage. Multiple studies have revealed distinct HgII -thiolate coordination preferences, among which linear HgII complexes are the most commonly observed in solution at physiological pH. Trigonal or tetrahedral geometries are formed at basic pH or in tight intraprotein Cys-rich metal sites. So far, no interprotein tetrahedral HgII complex formed at neutral pH has been reported. Rad50 protein is a part of the multiprotein MRN complex, a major player in DNA damage-repair processes. Its central region consists of a conserved CXXC motif that enables dimerization of two Rad50 molecules by coordinating ZnII . Dimerized motifs form a unique interprotein zinc hook domain (Hk) that is critical for the biological activity of the MRN. Using a series of length-differentiated peptide models of the Pyrococcus furiosus zinc hook domain, we investigated its interaction with HgII . Using UV-Vis, CD, PAC, and 199 Hg NMR spectroscopies as well as anisotropy decay, we discovered that all Rad50 fragments preferentially form homodimeric Hg(Hk)2 species with a distorted tetrahedral HgS4 coordination environment at physiological pH; this is the first example of an interprotein mercury site displaying tetrahedral geometry in solution. At higher HgII content, monomeric HgHk complexes with linear geometry are formed. The Hg(Cys)4 core of Rad50 is extremely stable and does not compete with cyanides, NAC, or DTT. Applying ITC, we found that the stability constant of the Rad50 Hg(Hk)2 complex is approximately three orders of magnitude higher than those of the strongest HgII complexes known to date.
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Affiliation(s)
- Marek Łuczkowski
- Department of Chemical BiologyFaculty of BiotechnologyUniversity of WrocławJoliot-Curie 14a50-383WrocławPoland
| | - Michał Padjasek
- Department of Chemical BiologyFaculty of BiotechnologyUniversity of WrocławJoliot-Curie 14a50-383WrocławPoland
| | - Józef Ba Tran
- Department of Chemical BiologyFaculty of BiotechnologyUniversity of WrocławJoliot-Curie 14a50-383WrocławPoland
| | - Lars Hemmingsen
- Department of ChemistryUniversity of CopenhagenUniversitetsparken 52100København ØDenmark
| | - Olga Kerber
- Department of Chemical BiologyFaculty of BiotechnologyUniversity of WrocławJoliot-Curie 14a50-383WrocławPoland
| | - Jelena Habjanič
- Department of ChemistryUniversity of ZurichWinterthurerstrasse 1908057ZürichSwitzerland
| | - Eva Freisinger
- Department of ChemistryUniversity of ZurichWinterthurerstrasse 1908057ZürichSwitzerland
| | - Artur Krężel
- Department of Chemical BiologyFaculty of BiotechnologyUniversity of WrocławJoliot-Curie 14a50-383WrocławPoland
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McCarthy-Leo C, Darwiche F, Tainsky MA. DNA Repair Mechanisms, Protein Interactions and Therapeutic Targeting of the MRN Complex. Cancers (Basel) 2022; 14:5278. [PMID: 36358700 PMCID: PMC9656488 DOI: 10.3390/cancers14215278] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 10/24/2022] [Accepted: 10/26/2022] [Indexed: 08/27/2023] Open
Abstract
Repair of a DNA double-strand break relies upon a pathway of proteins to identify damage, regulate cell cycle checkpoints, and repair the damage. This process is initiated by a sensor protein complex, the MRN complex, comprised of three proteins-MRE11, RAD50, and NBS1. After a double-stranded break, the MRN complex recruits and activates ATM, in-turn activating other proteins such as BRCA1/2, ATR, CHEK1/2, PALB2 and RAD51. These proteins have been the focus of many studies for their individual roles in hereditary cancer syndromes and are included on several genetic testing panels. These panels have enabled us to acquire large amounts of genetic data, much of which remains a challenge to interpret due to the presence of variants of uncertain significance (VUS). While the primary aim of clinical testing is to accurately and confidently classify variants in order to inform medical management, the presence of VUSs has led to ambiguity in genetic counseling. Pathogenic variants within MRN complex genes have been implicated in breast, ovarian, prostate, colon cancers and gliomas; however, the hundreds of VUSs within MRE11, RAD50, and NBS1 precludes the application of these data in genetic guidance of carriers. In this review, we discuss the MRN complex's role in DNA double-strand break repair, its interactions with other cancer predisposing genes, the variants that can be found within the three MRN complex genes, and the MRN complex's potential as an anti-cancer therapeutic target.
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Affiliation(s)
- Claire McCarthy-Leo
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Fatima Darwiche
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Michael A. Tainsky
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48201, USA
- Department of Oncology, Wayne State University School of Medicine, Detroit, MI 48201, USA
- Molecular Therapeutics Program, Karmanos Cancer Institute at Wayne State University School of Medicine, Detroit, MI 48201, USA
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15
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Kloeber JA, Lou Z. Critical DNA damaging pathways in tumorigenesis. Semin Cancer Biol 2022; 85:164-184. [PMID: 33905873 PMCID: PMC8542061 DOI: 10.1016/j.semcancer.2021.04.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2021] [Revised: 04/13/2021] [Accepted: 04/15/2021] [Indexed: 12/22/2022]
Abstract
The acquisition of DNA damage is an early driving event in tumorigenesis. Premalignant lesions show activated DNA damage responses and inactivation of DNA damage checkpoints promotes malignant transformation. However, DNA damage is also a targetable vulnerability in cancer cells. This requires a detailed understanding of the cellular and molecular mechanisms governing DNA integrity. Here, we review current work on DNA damage in tumorigenesis. We discuss DNA double strand break repair, how repair pathways contribute to tumorigenesis, and how double strand breaks are linked to the tumor microenvironment. Next, we discuss the role of oncogenes in promoting DNA damage through replication stress. Finally, we discuss our current understanding on DNA damage in micronuclei and discuss therapies targeting these DNA damage pathways.
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Affiliation(s)
- Jake A Kloeber
- Department of Oncology, Mayo Clinic, Rochester, MN, 55905, USA; Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN, 55905, USA; Mayo Clinic Medical Scientist Training Program, Mayo Clinic, Rochester, MN, 55905, USA
| | - Zhenkun Lou
- Department of Oncology, Mayo Clinic, Rochester, MN, 55905, USA.
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16
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Pizzul P, Casari E, Gnugnoli M, Rinaldi C, Corallo F, Longhese MP. The DNA damage checkpoint: A tale from budding yeast. Front Genet 2022; 13:995163. [PMID: 36186482 PMCID: PMC9520983 DOI: 10.3389/fgene.2022.995163] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 08/30/2022] [Indexed: 11/30/2022] Open
Abstract
Studies performed in the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe have led the way in defining the DNA damage checkpoint and in identifying most of the proteins involved in this regulatory network, which turned out to have structural and functional equivalents in humans. Subsequent experiments revealed that the checkpoint is an elaborate signal transduction pathway that has the ability to sense and signal the presence of damaged DNA and transduce this information to influence a multifaceted cellular response that is essential for cancer avoidance. This review focuses on the work that was done in Saccharomyces cerevisiae to articulate the checkpoint concept, to identify its players and the mechanisms of activation and deactivation.
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17
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Genome-wide CRISPR screen identified Rad18 as a determinant of doxorubicin sensitivity in osteosarcoma. JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2022; 41:154. [PMID: 35459258 PMCID: PMC9034549 DOI: 10.1186/s13046-022-02344-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 03/25/2022] [Indexed: 12/14/2022]
Abstract
Background Osteosarcoma (OS) is a malignant bone tumor mostly occurring in children and adolescents, while chemotherapy resistance often develops and the mechanisms involved remain challenging to be fully investigated. Methods Genome-wide CRISPR screening combined with transcriptomic sequencing were used to identify the critical genes of doxorubicin resistance. Analysis of clinical samples and datasets, and in vitro and in vivo experiments (including CCK-8, apoptosis, western blot, qRT-PCR and mouse models) were applied to confirm the function of these genes. The bioinformatics and IP-MS assays were utilized to further verify the downstream pathway. RGD peptide-directed and exosome-delivered siRNA were developed for the novel therapy strategy. Results We identified that E3 ubiquitin-protein ligase Rad18 (Rad18) contributed to doxorubicin-resistance in OS. Further exploration revealed that Rad18 interact with meiotic recombination 11 (MRE11) to promote the formation of the MRE11-RAD50-NBS1 (MRN) complex, facilitating the activation of the homologous recombination (HR) pathway, which ultimately mediated DNA damage tolerance and leaded to a poor prognosis and chemotherapy response in patients with OS. Rad18-knockout effectively restored the chemotherapy response in vitro and in vivo. Also, RGD-exosome loading chemically modified siRad18 combined with doxorubicin, where exosome and chemical modification guaranteed the stability of siRad18 and the RGD peptide provided prominent targetability, had significantly improved antitumor activity of doxorubicin. Conclusions Collectively, our study identifies Rad18 as a driver of OS doxorubicin resistance that promotes the HR pathway and indicates that targeting Rad18 is an effective approach to overcome chemotherapy resistance in OS. Supplementary Information The online version contains supplementary material available at 10.1186/s13046-022-02344-y.
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18
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Canny MD, Latham M. LRET-derived HADDOCK structural models describe the conformational heterogeneity required for DNA cleavage by the Mre11-Rad50 DNA damage repair complex. eLife 2022; 11:69579. [PMID: 35084331 PMCID: PMC8824468 DOI: 10.7554/elife.69579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 01/26/2022] [Indexed: 11/13/2022] Open
Abstract
The Mre11-Rad50-Nbs1 protein complex is one of the first responders to DNA double-strand breaks. Studies have shown that the catalytic activities of the evolutionarily conserved Mre11-Rad50 (MR) core complex depend on an ATP-dependent global conformational change that takes the macromolecule from an open, extended structure in the absence of ATP to a closed, globular structure when ATP is bound. We have previously identified an additional ‘partially open’ conformation using luminescence resonance energy transfer (LRET) experiments. Here, a combination of LRET and the molecular docking program HADDOCK was used to further investigate this partially open state and identify three conformations of MR in solution: closed, partially open, and open, which are in addition to the extended, apo conformation. Mutants disrupting specific Mre11-Rad50 interactions within each conformation were used in nuclease activity assays on a variety of DNA substrates to help put the three states into a functional perspective. LRET data collected on MR bound to DNA demonstrate that the three conformations also exist when nuclease substrates are bound. These models were further supported with small-angle X-ray scattering data, which corroborate the presence of multiple states in solution. Together, the data suggest a mechanism for the nuclease activity of the MR complex along the DNA.
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Affiliation(s)
- Marella D Canny
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, United States
| | - Michael Latham
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, United States
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19
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De Falco M, De Felice M. Take a Break to Repair: A Dip in the World of Double-Strand Break Repair Mechanisms Pointing the Gaze on Archaea. Int J Mol Sci 2021; 22:ijms222413296. [PMID: 34948099 PMCID: PMC8708640 DOI: 10.3390/ijms222413296] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 12/06/2021] [Accepted: 12/07/2021] [Indexed: 12/24/2022] Open
Abstract
All organisms have evolved many DNA repair pathways to counteract the different types of DNA damages. The detection of DNA damage leads to distinct cellular responses that bring about cell cycle arrest and the induction of DNA repair mechanisms. In particular, DNA double-strand breaks (DSBs) are extremely toxic for cell survival, that is why cells use specific mechanisms of DNA repair in order to maintain genome stability. The choice among the repair pathways is mainly linked to the cell cycle phases. Indeed, if it occurs in an inappropriate cellular context, it may cause genome rearrangements, giving rise to many types of human diseases, from developmental disorders to cancer. Here, we analyze the most recent remarks about the main pathways of DSB repair with the focus on homologous recombination. A thorough knowledge in DNA repair mechanisms is pivotal for identifying the most accurate treatments in human diseases.
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20
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D'Errico M, Parlanti E, Pascucci B, Filomeni G, Mastroberardino PG, Dogliotti E. The interplay between mitochondrial functionality and genome integrity in the prevention of human neurologic diseases. Arch Biochem Biophys 2021; 710:108977. [PMID: 34174223 DOI: 10.1016/j.abb.2021.108977] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 06/18/2021] [Accepted: 06/19/2021] [Indexed: 12/23/2022]
Abstract
As mitochondria are vulnerable to oxidative damage and represent the main source of reactive oxygen species (ROS), they are considered key tuners of ROS metabolism and buffering, whose dysfunction can progressively impact neuronal networks and disease. Defects in DNA repair and DNA damage response (DDR) may also affect neuronal health and lead to neuropathology. A number of congenital DNA repair and DDR defective syndromes, indeed, show neurological phenotypes, and a growing body of evidence indicate that defects in the mechanisms that control genome stability in neurons acts as aging-related modifiers of common neurodegenerative diseases such as Alzheimer, Parkinson's, Huntington diseases and Amyotrophic Lateral Sclerosis. In this review we elaborate on the established principles and recent concepts supporting the hypothesis that deficiencies in either DNA repair or DDR might contribute to neurodegeneration via mechanisms involving mitochondrial dysfunction/deranged metabolism.
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Affiliation(s)
| | - Eleonora Parlanti
- Department of Environment and Health, Istituto Superiore di Sanità, Rome, Italy
| | - Barbara Pascucci
- Institute of Crystallography, Consiglio Nazionale Delle Ricerche, Rome, Italy
| | - Giuseppe Filomeni
- Redox Biology, Danish Cancer Society Research Center, Copenhagen, Denmark; Center for Healthy Aging, Copenhagen University, Copenhagen, Denmark; Department of Biology, University of Rome Tor Vergata, Rome, Italy
| | - Pier Giorgio Mastroberardino
- Department of Molecular Genetics, Erasmus MC, Rotterdam, the Netherlands; IFOM- FIRC Institute of Molecular Oncology, Milan, Italy; Department of Life, Health and Environmental Sciences, University of L'Aquila, L'Aquila, Italy
| | - Eugenia Dogliotti
- Department of Environment and Health, Istituto Superiore di Sanità, Rome, Italy.
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21
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Tomasini PP, Guecheva TN, Leguisamo NM, Péricart S, Brunac AC, Hoffmann JS, Saffi J. Analyzing the Opportunities to Target DNA Double-Strand Breaks Repair and Replicative Stress Responses to Improve Therapeutic Index of Colorectal Cancer. Cancers (Basel) 2021; 13:3130. [PMID: 34201502 PMCID: PMC8268241 DOI: 10.3390/cancers13133130] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 06/15/2021] [Accepted: 06/18/2021] [Indexed: 12/22/2022] Open
Abstract
Despite the ample improvements of CRC molecular landscape, the therapeutic options still rely on conventional chemotherapy-based regimens for early disease, and few targeted agents are recommended for clinical use in the metastatic setting. Moreover, the impact of cytotoxic, targeted agents, and immunotherapy combinations in the metastatic scenario is not fully satisfactory, especially the outcomes for patients who develop resistance to these treatments need to be improved. Here, we examine the opportunity to consider therapeutic agents targeting DNA repair and DNA replication stress response as strategies to exploit genetic or functional defects in the DNA damage response (DDR) pathways through synthetic lethal mechanisms, still not explored in CRC. These include the multiple actors involved in the repair of DNA double-strand breaks (DSBs) through homologous recombination (HR), classical non-homologous end joining (NHEJ), and microhomology-mediated end-joining (MMEJ), inhibitors of the base excision repair (BER) protein poly (ADP-ribose) polymerase (PARP), as well as inhibitors of the DNA damage kinases ataxia-telangiectasia and Rad3 related (ATR), CHK1, WEE1, and ataxia-telangiectasia mutated (ATM). We also review the biomarkers that guide the use of these agents, and current clinical trials with targeted DDR therapies.
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Affiliation(s)
- Paula Pellenz Tomasini
- Laboratory of Genetic Toxicology, Federal University of Health Sciences of Porto Alegre, Avenida Sarmento Leite, 245, Porto Alegre 90050-170, Brazil; (P.P.T.); (N.M.L.)
- Post-Graduation Program in Cell and Molecular Biology, Federal University of Rio Grande do Sul, Avenida Bento Gonçalves, 9500, Porto Alegre 91501-970, Brazil
| | - Temenouga Nikolova Guecheva
- Cardiology Institute of Rio Grande do Sul, University Foundation of Cardiology (IC-FUC), Porto Alegre 90620-000, Brazil;
| | - Natalia Motta Leguisamo
- Laboratory of Genetic Toxicology, Federal University of Health Sciences of Porto Alegre, Avenida Sarmento Leite, 245, Porto Alegre 90050-170, Brazil; (P.P.T.); (N.M.L.)
| | - Sarah Péricart
- Laboratoire D’Excellence Toulouse Cancer (TOUCAN), Laboratoire de Pathologie, Institut Universitaire du Cancer-Toulouse, Oncopole, 1 Avenue Irène-Joliot-Curie, 31059 Toulouse, France; (S.P.); (A.-C.B.); (J.S.H.)
| | - Anne-Cécile Brunac
- Laboratoire D’Excellence Toulouse Cancer (TOUCAN), Laboratoire de Pathologie, Institut Universitaire du Cancer-Toulouse, Oncopole, 1 Avenue Irène-Joliot-Curie, 31059 Toulouse, France; (S.P.); (A.-C.B.); (J.S.H.)
| | - Jean Sébastien Hoffmann
- Laboratoire D’Excellence Toulouse Cancer (TOUCAN), Laboratoire de Pathologie, Institut Universitaire du Cancer-Toulouse, Oncopole, 1 Avenue Irène-Joliot-Curie, 31059 Toulouse, France; (S.P.); (A.-C.B.); (J.S.H.)
| | - Jenifer Saffi
- Laboratory of Genetic Toxicology, Federal University of Health Sciences of Porto Alegre, Avenida Sarmento Leite, 245, Porto Alegre 90050-170, Brazil; (P.P.T.); (N.M.L.)
- Post-Graduation Program in Cell and Molecular Biology, Federal University of Rio Grande do Sul, Avenida Bento Gonçalves, 9500, Porto Alegre 91501-970, Brazil
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22
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Abstract
The MRN complex (MRX in Saccharomyces cerevisiae, made of Mre11, Rad50 and Nbs1/Xrs2) initiates double-stranded DNA break repair and activates the Tel1/ATM kinase in the DNA damage response. Telomeres counter both outcomes at chromosome ends, partly by keeping MRN-ATM in check. We show that MRX is disabled by telomeric protein Rif2 through an N-terminal motif (MIN, MRN/X-inhibitory motif). MIN executes suppression of Tel1, DNA end-resection and non-homologous end joining by binding the Rad50 N-terminal region. Our data suggest that MIN promotes a transition within MRX that is not conductive for endonuclease activity, DNA-end tethering or Tel1 kinase activation, highlighting an Achilles' heel in MRN, which we propose is also exploited by the RIF2 paralog ORC4 (Origin Recognition Complex 4) in Kluyveromyces lactis and the Schizosaccharomyces pombe telomeric factor Taz1, which is evolutionarily unrelated to Orc4/Rif2. This raises the possibility that analogous mechanisms might be deployed in other eukaryotes as well.
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23
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Tannous EA, Burgers PM. Novel insights into the mechanism of cell cycle kinases Mec1(ATR) and Tel1(ATM). Crit Rev Biochem Mol Biol 2021; 56:441-454. [PMID: 34151669 DOI: 10.1080/10409238.2021.1925218] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
DNA replication is a highly precise process which usually functions in a perfect rhythm with cell cycle progression. However, cells are constantly faced with various kinds of obstacles such as blocks in DNA replication, lack of availability of precursors and improper chromosome alignment. When these problems are not addressed, they may lead to chromosome instability and the accumulation of mutations, and even cell death. Therefore, the cell has developed response mechanisms to keep most of these situations under control. Of the many factors that participate in this DNA damage response, members of the family of phosphatidylinositol 3-kinase-related protein kinases (PIKKs) orchestrate the response landscape. Our understanding of two members of the PIKK family, human ATR (yeast Mec1) and ATM (yeast Tel1), and their associated partner proteins, has shown substantial progress through recent biochemical and structural studies. Emerging structural information of these unique kinases show common features that reveal the mechanism of kinase activity.
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Affiliation(s)
- Elias A Tannous
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO, USA
| | - Peter M Burgers
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO, USA
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24
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Thada V, Cortez D. ATR activation is regulated by dimerization of ATR activating proteins. J Biol Chem 2021; 296:100455. [PMID: 33636182 PMCID: PMC7994790 DOI: 10.1016/j.jbc.2021.100455] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 02/17/2021] [Accepted: 02/22/2021] [Indexed: 02/06/2023] Open
Abstract
The checkpoint kinase ATR regulates DNA repair, cell cycle progression, and other DNA damage and replication stress responses. ATR signaling is stimulated by an ATR activating protein, and in metazoan cells, there are at least two ATR activators: TOPBP1 and ETAA1. Current evidence indicates TOPBP1 and ETAA1 activate ATR via the same biochemical mechanism, but several aspects of this mechanism remain undefined. For example, ATR and its obligate binding partner ATR interacting protein (ATRIP) form a tetrameric complex consisting of two ATR and two ATRIP molecules, but whether TOPBP1 or ETAA1 dimerization is similarly required for ATR function is unclear. Here, we show that fusion of the TOPBP1 and ETAA1 ATR activation domains (AADs) to dimeric tags makes them more potent activators of ATR in vitro. Furthermore, induced dimerization of both AADs using chemical dimerization of a modified FKBP tag enhances ATR kinase activation and signaling in cells. ETAA1 forms oligomeric complexes mediated by regions of the protein that are predicted to be intrinsically disordered. Induced dimerization of a “mini-ETAA1” protein that contains the AAD and Replication Protein A (RPA) interaction motifs enhances ATR signaling, rescues cellular hypersensitivity to DNA damaging agents, and suppresses micronuclei formation in ETAA1-deficient cells. Together, our results indicate that TOPBP1 and ETAA1 dimerization is important for optimal ATR signaling and genome stability.
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Affiliation(s)
- Vaughn Thada
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville Tennessee, USA
| | - David Cortez
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville Tennessee, USA.
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25
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Chansel-Da Cruz M, Hohl M, Ceppi I, Kermasson L, Maggiorella L, Modesti M, de Villartay JP, Ileri T, Cejka P, Petrini JHJ, Revy P. A Disease-Causing Single Amino Acid Deletion in the Coiled-Coil Domain of RAD50 Impairs MRE11 Complex Functions in Yeast and Humans. Cell Rep 2020; 33:108559. [PMID: 33378670 PMCID: PMC7788285 DOI: 10.1016/j.celrep.2020.108559] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 10/30/2020] [Accepted: 12/04/2020] [Indexed: 12/20/2022] Open
Abstract
The MRE11-RAD50-NBS1 complex plays a central role in response to DNA double-strand breaks. Here, we identify a patient with bone marrow failure and developmental defects caused by biallelic RAD50 mutations. One of the mutations creates a null allele, whereas the other (RAD50E1035Δ) leads to the loss of a single residue in the heptad repeats within the RAD50 coiled-coil domain. This mutation represents a human RAD50 separation-of-function mutation that impairs DNA repair, DNA replication, and DNA end resection without affecting ATM-dependent DNA damage response. Purified recombinant proteins indicate that RAD50E1035Δ impairs MRE11 nuclease activity. The corresponding mutation in Saccharomyces cerevisiae causes severe thermosensitive defects in both DNA repair and Tel1ATM-dependent signaling. These findings demonstrate that a minor heptad break in the RAD50 coiled coil suffices to impede MRE11 complex functions in human and yeast. Furthermore, these results emphasize the importance of the RAD50 coiled coil to regulate MRE11-dependent DNA end resection in humans.
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Affiliation(s)
- Marie Chansel-Da Cruz
- INSERM UMR 1163, Laboratory of Genome Dynamics in the Immune System, Equipe Labellisée la Ligue contre le Cancer, Paris, France; University of Paris-Sorbonne Paris Cité University, Imagine Institute, Paris, France; Genomic Vision, R&D Innovation Department, Bagneux, France
| | - Marcel Hohl
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Ilaria Ceppi
- Institute for Research in Biomedicine, Università della Svizzera Italiana (USI), Faculty of Biomedical Sciences, Via Vincenzo Vela 6, 6500 Bellinzona, Switzerland; Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), 8093 Zürich, Switzerland
| | - Laëtitia Kermasson
- INSERM UMR 1163, Laboratory of Genome Dynamics in the Immune System, Equipe Labellisée la Ligue contre le Cancer, Paris, France; University of Paris-Sorbonne Paris Cité University, Imagine Institute, Paris, France
| | | | - Mauro Modesti
- Cancer Research Center of Marseille, CNRS UMR7258, INSERM U1068, Institut Paoli-Calmettes, Aix-Marseille Université, Marseille, France
| | - Jean-Pierre de Villartay
- INSERM UMR 1163, Laboratory of Genome Dynamics in the Immune System, Equipe Labellisée la Ligue contre le Cancer, Paris, France; University of Paris-Sorbonne Paris Cité University, Imagine Institute, Paris, France
| | - Talia Ileri
- Ankara University School of Medicine, Pediatric Hematology and Oncology, Ankara, Turkey
| | - Petr Cejka
- Institute for Research in Biomedicine, Università della Svizzera Italiana (USI), Faculty of Biomedical Sciences, Via Vincenzo Vela 6, 6500 Bellinzona, Switzerland; Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), 8093 Zürich, Switzerland
| | - John H J Petrini
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Patrick Revy
- INSERM UMR 1163, Laboratory of Genome Dynamics in the Immune System, Equipe Labellisée la Ligue contre le Cancer, Paris, France; University of Paris-Sorbonne Paris Cité University, Imagine Institute, Paris, France.
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26
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Zabolotnaya E, Mela I, Henderson RM, Robinson NP. Turning the Mre11/Rad50 DNA repair complex on its head: lessons from SMC protein hinges, dynamic coiled-coil movements and DNA loop-extrusion? Biochem Soc Trans 2020; 48:2359-2376. [PMID: 33300987 PMCID: PMC7752040 DOI: 10.1042/bst20170168] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Revised: 10/19/2020] [Accepted: 10/22/2020] [Indexed: 12/12/2022]
Abstract
The bacterial SbcC/SbcD DNA repair proteins were identified over a quarter of a century ago. Following the subsequent identification of the homologous Mre11/Rad50 complex in the eukaryotes and archaea, it has become clear that this conserved chromosomal processing machinery is central to DNA repair pathways and the maintenance of genomic stability in all forms of life. A number of experimental studies have explored this intriguing genome surveillance machinery, yielding significant insights and providing conceptual advances towards our understanding of how this complex operates to mediate DNA repair. However, the inherent complexity and dynamic nature of this chromosome-manipulating machinery continue to obfuscate experimental interrogations, and details regarding the precise mechanisms that underpin the critical repair events remain unanswered. This review will summarize our current understanding of the dramatic structural changes that occur in Mre11/Rad50 complex to mediate chromosomal tethering and accomplish the associated DNA processing events. In addition, undetermined mechanistic aspects of the DNA enzymatic pathways driven by this vital yet enigmatic chromosomal surveillance and repair apparatus will be discussed. In particular, novel and putative models of DNA damage recognition will be considered and comparisons will be made between the modes of action of the Rad50 protein and other related ATPases of the overarching SMC superfamily.
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Affiliation(s)
| | - Ioanna Mela
- Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, U.K
| | | | - Nicholas P. Robinson
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster LA1 4YG, U.K
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27
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Beikzadeh M, Latham MP. The dynamic nature of the Mre11-Rad50 DNA break repair complex. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2020; 163:14-22. [PMID: 33121960 DOI: 10.1016/j.pbiomolbio.2020.10.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 10/02/2020] [Accepted: 10/23/2020] [Indexed: 01/18/2023]
Abstract
The Mre11-Rad50-Nbs1/Xrs2 protein complex plays a pivotal role in the detection and repair of DNA double strand breaks. Through traditional and emerging structural biology techniques, various functional structural states of this complex have been visualized; however, relatively little is known about the transitions between these states. Indeed, it is these structural transitions that are important for Mre11-Rad50-mediated DNA unwinding at a break and the activation of downstream repair signaling events. Here, we present a brief overview of the current understanding of the structure of the core Mre11-Rad50 complex. We then highlight our recent studies emphasizing the contributions of solution state NMR spectroscopy and other biophysical techniques in providing insight into the structures and dynamics associated with Mre11-Rad50 functions.
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Affiliation(s)
- Mahtab Beikzadeh
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX, USA
| | - Michael P Latham
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX, USA.
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28
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Zhao F, Kim W, Kloeber JA, Lou Z. DNA end resection and its role in DNA replication and DSB repair choice in mammalian cells. Exp Mol Med 2020; 52:1705-1714. [PMID: 33122806 PMCID: PMC8080561 DOI: 10.1038/s12276-020-00519-1] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 08/29/2020] [Accepted: 09/09/2020] [Indexed: 12/19/2022] Open
Abstract
DNA end resection has a key role in double-strand break repair and DNA replication. Defective DNA end resection can cause malfunctions in DNA repair and replication, leading to greater genomic instability. DNA end resection is initiated by MRN-CtIP generating short, 3′-single-stranded DNA (ssDNA). This newly generated ssDNA is further elongated by multiple nucleases and DNA helicases, such as EXO1, DNA2, and BLM. Effective DNA end resection is essential for error-free homologous recombination DNA repair, the degradation of incorrectly replicated DNA and double-strand break repair choice. Because of its importance in DNA repair, DNA end resection is strictly regulated. Numerous mechanisms have been reported to regulate the initiation, extension, and termination of DNA end resection. Here, we review the general process of DNA end resection and its role in DNA replication and repair pathway choice. Carefully regulated enzymatic processing of the ends of DNA strands is essential for efficient replication and damage repair while also minimizing the risk of genomic instability. Replication and repair depend on a mechanism known as DNA resection, in which enzymes trim back double-stranded DNA ends to leave single-stranded overhangs. Zhenkun Lou and colleagues at the Mayo Clinic in Rochester, USA, have reviewed the various steps involved in the initiation and control of DNA resection. There are multiple different DNA repair processes, and the manner in which resection occurs can determine which of these processes subsequently takes place. The authors note that cancer cells rely heavily on these repair pathways to survive radiotherapy and chemotherapy, and highlight research opportunities that might reveal therapeutically useful vulnerabilities in the resection mechanism.
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Affiliation(s)
- Fei Zhao
- Department of Oncology, Mayo Clinic, Rochester, MN, 55905, USA
| | - Wootae Kim
- Department of Oncology, Mayo Clinic, Rochester, MN, 55905, USA
| | - Jake A Kloeber
- Department of Oncology, Mayo Clinic, Rochester, MN, 55905, USA.,Mayo Clinic Medical Scientist Training Program, Mayo Clinic, Rochester, MN, 55905, USA.,Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN, 55905, USA
| | - Zhenkun Lou
- Department of Oncology, Mayo Clinic, Rochester, MN, 55905, USA.
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29
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A Survey of Reported Disease-Related Mutations in the MRE11-RAD50-NBS1 Complex. Cells 2020; 9:cells9071678. [PMID: 32668560 PMCID: PMC7407228 DOI: 10.3390/cells9071678] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 07/01/2020] [Accepted: 07/06/2020] [Indexed: 12/24/2022] Open
Abstract
The MRE11-RAD50-NBS1 (MRN) protein complex is one of the primary vehicles for repairing DNA double strand breaks and maintaining the genomic stability within the cell. The role of the MRN complex to recognize and process DNA double-strand breaks as well as signal other damage response factors is critical for maintaining proper cellular function. Mutations in any one of the components of the MRN complex that effect function or expression of the repair machinery could be detrimental to the cell and may initiate and/or propagate disease. Here, we discuss, in a structural and biochemical context, mutations in each of the three MRN components that have been associated with diseases such as ataxia telangiectasia-like disorder (ATLD), Nijmegen breakage syndrome (NBS), NBS-like disorder (NBSLD) and certain types of cancers. Overall, deepening our understanding of disease-causing mutations of the MRN complex at the structural and biochemical level is foundational to the future aim of treating diseases associated with these aberrations.
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30
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Modes of action of the archaeal Mre11/Rad50 DNA-repair complex revealed by fast-scan atomic force microscopy. Proc Natl Acad Sci U S A 2020; 117:14936-14947. [PMID: 32541055 PMCID: PMC7334584 DOI: 10.1073/pnas.1915598117] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The Mre11/Rad50 (M/R) complex forms the core of an essential DNA-repair complex, conserved in all divisions of life. Here we investigate this complex from the thermophilic archaeon Sulfolobus acidocaldarius using real-time atomic force microscopy. We demonstrate that the coiled-coil regions of Rad50 facilitate M/R interaction with DNA and permit substrate translocation until a free end is encountered. We also observe that the M/R complex drives unprecedented unwinding of the DNA duplexes. Taking these findings together, we provide a model for how the M/R complex can identify DNA double-strand breaks and orchestrate repair events. Mre11 and Rad50 (M/R) proteins are part of an evolutionarily conserved macromolecular apparatus that maintains genomic integrity through repair pathways. Prior structural studies have revealed that this apparatus is extremely dynamic, displaying flexibility in the long coiled-coil regions of Rad50, a member of the structural maintenance of chromosome (SMC) superfamily of ATPases. However, many details of the mechanics of M/R chromosomal manipulation during DNA-repair events remain unclear. Here, we investigate the properties of the thermostable M/R complex from the archaeon Sulfolobus acidocaldarius using atomic force microscopy (AFM) to understand how this macromolecular machinery orchestrates DNA repair. While previous studies have observed canonical interactions between the globular domains of M/R and DNA, we observe transient interactions between DNA substrates and the Rad50 coiled coils. Fast-scan AFM videos (at 1–2 frames per second) of M/R complexes reveal that these interactions result in manipulation and translocation of the DNA substrates. Our study also shows dramatic and unprecedented ATP-dependent DNA unwinding events by the M/R complex, which extend hundreds of base pairs in length. Supported by molecular dynamic simulations, we propose a model for M/R recognition at DNA breaks in which the Rad50 coiled coils aid movement along DNA substrates until a DNA end is encountered, after which the DNA unwinding activity potentiates the downstream homologous recombination (HR)-mediated DNA repair.
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31
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Tisi R, Vertemara J, Zampella G, Longhese MP. Functional and structural insights into the MRX/MRN complex, a key player in recognition and repair of DNA double-strand breaks. Comput Struct Biotechnol J 2020; 18:1137-1152. [PMID: 32489527 PMCID: PMC7260605 DOI: 10.1016/j.csbj.2020.05.013] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Revised: 05/07/2020] [Accepted: 05/09/2020] [Indexed: 01/20/2023] Open
Abstract
Chromosomal DNA double-strand breaks (DSBs) are potentially lethal DNA lesions that pose a significant threat to genome stability and therefore need to be repaired to preserve genome integrity. Eukaryotic cells possess two main mechanisms for repairing DSBs: non-homologous end-joining (NHEJ) and homologous recombination (HR). HR requires that the 5' terminated strands at both DNA ends are nucleolytically degraded by a concerted action of nucleases in a process termed DNA-end resection. This degradation leads to the formation of 3'-ended single-stranded DNA (ssDNA) ends that are essential to use homologous DNA sequences for repair. The evolutionarily conserved Mre11-Rad50-Xrs2/NBS1 complex (MRX/MRN) has enzymatic and structural activities to initiate DSB resection and to maintain the DSB ends tethered to each other for their repair. Furthermore, it is required to recruit and activate the protein kinase Tel1/ATM, which plays a key role in DSB signaling. All these functions depend on ATP-regulated DNA binding and nucleolytic activities of the complex. Several structures have been obtained in recent years for Mre11 and Rad50 subunits from archaea, and a few from the bacterial and eukaryotic orthologs. Nevertheless, the mechanism of activation of this protein complex is yet to be fully elucidated. In this review, we focused on recent biophysical and structural insights on the MRX complex and their interplay.
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Affiliation(s)
- Renata Tisi
- Dipartimento di Biotecnologie and Bioscienze, Università degli Studi di Milano-Bicocca, Milan, Italy
| | - Jacopo Vertemara
- Dipartimento di Biotecnologie and Bioscienze, Università degli Studi di Milano-Bicocca, Milan, Italy
| | - Giuseppe Zampella
- Dipartimento di Biotecnologie and Bioscienze, Università degli Studi di Milano-Bicocca, Milan, Italy
| | - Maria Pia Longhese
- Dipartimento di Biotecnologie and Bioscienze, Università degli Studi di Milano-Bicocca, Milan, Italy
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32
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Colombo CV, Gnugnoli M, Gobbini E, Longhese MP. How do cells sense DNA lesions? Biochem Soc Trans 2020; 48:677-691. [PMID: 32219379 DOI: 10.1042/bst20191118] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 03/06/2020] [Accepted: 03/12/2020] [Indexed: 12/17/2023]
Abstract
DNA is exposed to both endogenous and exogenous DNA damaging agents that chemically modify it. To counteract the deleterious effects exerted by DNA lesions, eukaryotic cells have evolved a network of cellular pathways, termed DNA damage response (DDR). The DDR comprises both mechanisms devoted to repair DNA lesions and signal transduction pathways that sense DNA damage and transduce this information to specific cellular targets. These targets, in turn, impact a wide range of cellular processes including DNA replication, DNA repair and cell cycle transitions. The importance of the DDR is highlighted by the fact that DDR inactivation is commonly found in cancer and causes many different human diseases. The protein kinases ATM and ATR, as well as their budding yeast orthologs Tel1 and Mec1, act as master regulators of the DDR. The initiating events in the DDR entail both DNA lesion recognition and assembly of protein complexes at the damaged DNA sites. Here, we review what is known about the early steps of the DDR.
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Affiliation(s)
- Chiara Vittoria Colombo
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Piazza della Scienza 2, 20126 Milano, Italy
| | - Marco Gnugnoli
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Piazza della Scienza 2, 20126 Milano, Italy
| | - Elisa Gobbini
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Piazza della Scienza 2, 20126 Milano, Italy
| | - Maria Pia Longhese
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Piazza della Scienza 2, 20126 Milano, Italy
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33
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Boswell ZK, Canny MD, Buschmann TA, Sang J, Latham MP. Adjacent mutations in the archaeal Rad50 ABC ATPase D-loop disrupt allosteric regulation of ATP hydrolysis through different mechanisms. Nucleic Acids Res 2020; 48:2457-2472. [PMID: 31889185 PMCID: PMC7049730 DOI: 10.1093/nar/gkz1228] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Revised: 11/25/2019] [Accepted: 12/20/2019] [Indexed: 11/29/2022] Open
Abstract
DNA damage is the driving force for mutation and genomic instability, which can both lead to cell death or carcinogenesis. DNA double strand breaks are detected and processed in part by the Mre11-Rad50-Nbs1 protein complex. Although the Mre11-Rad50-Nbs1 complex is essential, several spontaneous mutations have been noted in various cancers. One of these mutations, within a conserved motif of Rad50, resulted in an outlier curative response in a clinical trial. We show through biochemical and biophysical characterization that this cancer-associated mutation and a second mutation to the adjacent residue, previously described in a breast cancer patient, both have gain-of-function Rad50 ATP hydrolysis activity that results not from faster association of the ATP-bound form but faster dissociation leading to less stable Rad50 dimer. This disruption impairs the regulatory functions of the protein complex leading to a loss of exonuclease activity from Mre11. Interestingly, these two mutations affect Rad50 structure and dynamics quite differently. These studies describe the relationship between function, structure, and molecular motions in improperly regulated Rad50, which reveal the underlying biophysical mechanism for how these two cancer-associated mutations affect the cell.
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Affiliation(s)
- Zachary K Boswell
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409-1061, USA
| | - Marella D Canny
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409-1061, USA
| | - Tanner A Buschmann
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409-1061, USA
| | - Julie Sang
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409-1061, USA
| | - Michael P Latham
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409-1061, USA
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34
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Padjasek M, Maciejczyk M, Nowakowski M, Kerber O, Pyrka M, Koźmiński W, Krężel A. Metal Exchange in the Interprotein Zn II -Binding Site of the Rad50 Hook Domain: Structural Insights into Cd II -Induced DNA-Repair Inhibition. Chemistry 2020; 26:3297-3313. [PMID: 31846102 PMCID: PMC7155053 DOI: 10.1002/chem.201904942] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 12/12/2019] [Indexed: 11/17/2022]
Abstract
CdII is a major genotoxic agent that readily displaces ZnII in a multitude of zinc proteins, abrogates redox homeostasis, and deregulates cellular metalloproteome. To date, this displacement has been described mostly for cysteine(Cys)-rich intraprotein binding sites in certain zinc finger domains and metallothioneins. To visualize how a ZnII -to-CdII swap can affect the target protein's status and thus understand the molecular basis of CdII -induced genotoxicity an intermolecular ZnII -binding site from the crucial DNA repair protein Rad50 and its zinc hook domain were examined. By using a length-varied peptide base, ZnII -to-CdII displacement in Rad50's hook domain is demonstrated to alter it in a bimodal fashion: 1) CdII induces around a two-orders-of-magnitude stabilization effect (log K 12 Zn II =20.8 vs. log K 12 Cd II =22.7), which defines an extremely high affinity of a peptide towards a metal ion, and 2) the displacement disrupts the overall assembly of the domain, as shown by NMR spectroscopic and anisotropy decay data. Based on the results, a new model explaining the molecular mechanism of CdII genotoxicity that underlines CdII 's impact on Rad50's dimer stability and quaternary structure that could potentially result in abrogation of the major DNA damage response pathway is proposed.
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Affiliation(s)
- Michał Padjasek
- Department of Chemical BiologyFaculty of BiotechnologyUniversity of WrocławJoliot-Curie 14a50-383WrocławPoland
| | - Maciej Maciejczyk
- Department of Physics and BiophysicsFaculty of Food ScienceUniversity of Warmia and Mazury in OlsztynOczapowskiego 410-719OlsztynPoland
| | - Michał Nowakowski
- Faculty of ChemistryBiological and Chemical Research CenterUniversity of WarsawŻwirki i Wigury 10102-089WarsawPoland
| | - Olga Kerber
- Department of Chemical BiologyFaculty of BiotechnologyUniversity of WrocławJoliot-Curie 14a50-383WrocławPoland
| | - Maciej Pyrka
- Department of Physics and BiophysicsFaculty of Food ScienceUniversity of Warmia and Mazury in OlsztynOczapowskiego 410-719OlsztynPoland
| | - Wiktor Koźmiński
- Faculty of ChemistryBiological and Chemical Research CenterUniversity of WarsawŻwirki i Wigury 10102-089WarsawPoland
| | - Artur Krężel
- Department of Chemical BiologyFaculty of BiotechnologyUniversity of WrocławJoliot-Curie 14a50-383WrocławPoland
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35
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Hohl M, Mojumdar A, Hailemariam S, Kuryavyi V, Ghisays F, Sorenson K, Chang M, Taylor BS, Patel DJ, Burgers PM, Cobb JA, Petrini JHJ. Modeling cancer genomic data in yeast reveals selection against ATM function during tumorigenesis. PLoS Genet 2020; 16:e1008422. [PMID: 32187176 PMCID: PMC7105138 DOI: 10.1371/journal.pgen.1008422] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Revised: 03/30/2020] [Accepted: 01/19/2020] [Indexed: 02/08/2023] Open
Abstract
The DNA damage response (DDR) comprises multiple functions that collectively preserve genomic integrity and suppress tumorigenesis. The Mre11 complex and ATM govern a major axis of the DDR and several lines of evidence implicate that axis in tumor suppression. Components of the Mre11 complex are mutated in approximately five percent of human cancers. Inherited mutations of complex members cause severe chromosome instability syndromes, such as Nijmegen Breakage Syndrome, which is associated with strong predisposition to malignancy. And in mice, Mre11 complex mutations are markedly more susceptible to oncogene- induced carcinogenesis. The complex is integral to all modes of DNA double strand break (DSB) repair and is required for the activation of ATM to effect DNA damage signaling. To understand which functions of the Mre11 complex are important for tumor suppression, we undertook mining of cancer genomic data from the clinical sequencing program at Memorial Sloan Kettering Cancer Center, which includes the Mre11 complex among the 468 genes assessed. Twenty five mutations in MRE11 and RAD50 were modeled in S. cerevisiae and in vitro. The mutations were chosen based on recurrence and conservation between human and yeast. We found that a significant fraction of tumor-borne RAD50 and MRE11 mutations exhibited separation of function phenotypes wherein Tel1/ATM activation was severely impaired while DNA repair functions were mildly or not affected. At the molecular level, the gene products of RAD50 mutations exhibited defects in ATP binding and hydrolysis. The data reflect the importance of Rad50 ATPase activity for Tel1/ATM activation and suggest that inactivation of ATM signaling confers an advantage to burgeoning tumor cells.
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Affiliation(s)
- Marcel Hohl
- Molecular Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America
| | - Aditya Mojumdar
- Departments of Biochemistry & Molecular Biology and Oncology, Robson DNA Science Centre, Arnie Charbonneau Cancer Institute, Cumming School of Medicine; University of Calgary, Calgary, Canada
| | - Sarem Hailemariam
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, Untied States of America
| | - Vitaly Kuryavyi
- Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America
| | - Fiorella Ghisays
- Molecular Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America
| | - Kyle Sorenson
- Departments of Biochemistry & Molecular Biology and Oncology, Robson DNA Science Centre, Arnie Charbonneau Cancer Institute, Cumming School of Medicine; University of Calgary, Calgary, Canada
| | - Matthew Chang
- Marie-Josée and Henry R. Kravis Center for Molecular Oncology, Memorial Sloan Kettering Cancer Center, New York, NY, USA; Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
| | - Barry S. Taylor
- Marie-Josée and Henry R. Kravis Center for Molecular Oncology, Memorial Sloan Kettering Cancer Center, New York, NY, USA; Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
| | - Dinshaw J. Patel
- Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America
| | - Peter M. Burgers
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, Untied States of America
| | - Jennifer A. Cobb
- Departments of Biochemistry & Molecular Biology and Oncology, Robson DNA Science Centre, Arnie Charbonneau Cancer Institute, Cumming School of Medicine; University of Calgary, Calgary, Canada
| | - John H. J. Petrini
- Molecular Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America
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36
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Tatebe H, Lim CT, Konno H, Shiozaki K, Shinohara A, Uchihashi T, Furukohri A. Rad50 zinc hook functions as a constitutive dimerization module interchangeable with SMC hinge. Nat Commun 2020; 11:370. [PMID: 31953386 PMCID: PMC6969161 DOI: 10.1038/s41467-019-14025-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 12/10/2019] [Indexed: 01/11/2023] Open
Abstract
The human Mre11/Rad50 complex is one of the key factors in genome maintenance pathways. Previous nanoscale imaging by atomic force microscopy (AFM) showed that the ring-like structure of the human Mre11/Rad50 complex transiently opens at the zinc hook of Rad50. However, imaging of the human Mre11/Rad50 complex by high-speed AFM shows that the Rad50 coiled-coil arms are consistently bridged by the dimerized hooks while the Mre11/Rad50 ring opens by disconnecting the head domains; resembling other SMC proteins such as cohesin or condensin. These architectural features are conserved in the yeast and bacterial Mre11/Rad50 complexes. Yeast strains harboring the chimeric Mre11/Rad50 complex containing the SMC hinge of bacterial condensin MukB instead of the RAD50 hook properly functions in DNA repair. We propose that the basic role of the Rad50 hook is similar to that of the SMC hinge, which serves as rather stable dimerization interface.
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Affiliation(s)
- Hisashi Tatebe
- Nara Institute of Science and Technology, Graduate School of Biological Sciences, Ikoma, Nara, 630-0192, Japan
| | - Chew Theng Lim
- Nara Institute of Science and Technology, Graduate School of Biological Sciences, Ikoma, Nara, 630-0192, Japan
| | - Hiroki Konno
- WPI Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa, 920-1192, Japan
| | - Kazuhiro Shiozaki
- Nara Institute of Science and Technology, Graduate School of Biological Sciences, Ikoma, Nara, 630-0192, Japan
- Department of Microbiology and Molecular Genetics, University of California, Davis, CA, 95616, USA
| | - Akira Shinohara
- Institute for Protein Research, Osaka University, Suita, Osaka, 565-0871, Japan
| | - Takayuki Uchihashi
- Department of Physics, Nagoya University, Nagoya, 464-8602, Japan.
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki, 444-8787, Japan.
| | - Asako Furukohri
- Institute for Protein Research, Osaka University, Suita, Osaka, 565-0871, Japan.
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37
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Chauhan N, Wagh V, Joshi P, Jariyal H. ATM and ATR checkpoint kinase pathways: A concise review. ADVANCES IN HUMAN BIOLOGY 2020. [DOI: 10.4103/aihb.aihb_78_19] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
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Keener R, Connelly CJ, Greider CW. Tel1 Activation by the MRX Complex Is Sufficient for Telomere Length Regulation but Not for the DNA Damage Response in Saccharomyces cerevisiae. Genetics 2019; 213:1271-1288. [PMID: 31645360 PMCID: PMC6893380 DOI: 10.1534/genetics.119.302713] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 10/17/2019] [Indexed: 12/26/2022] Open
Abstract
Previous models suggested that regulation of telomere length in Saccharomyces cerevisiae by Tel1(ATM) and Mec1(ATR) would parallel the established pathways regulating the DNA damage response. Here, we provide evidence that telomere length regulation differs from the DNA damage response in both the Tel1 and Mec1 pathways. We found that Rad53 mediates a Mec1 telomere length regulation pathway but is dispensable for Tel1 telomere length regulation, whereas in the DNA damage response, Rad53 is regulated by both Mec1 and Tel1 Using epistasis analysis with a Tel1 hypermorphic allele, Tel1-hy909, we found that the MRX complex is not required downstream of Tel1 for telomere elongation but is required downstream of Tel1 for the DNA damage response. Our data suggest that nucleolytic telomere end processing is not a required step for telomerase to elongate telomeres.
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Affiliation(s)
- Rebecca Keener
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
- Biochemistry, Cellular and Molecular Biology Graduate Program, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Carla J Connelly
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Carol W Greider
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
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Cassani C, Vertemara J, Bassani M, Marsella A, Tisi R, Zampella G, Longhese MP. The ATP-bound conformation of the Mre11-Rad50 complex is essential for Tel1/ATM activation. Nucleic Acids Res 2019; 47:3550-3567. [PMID: 30698745 PMCID: PMC6468247 DOI: 10.1093/nar/gkz038] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 12/17/2018] [Accepted: 01/15/2019] [Indexed: 01/01/2023] Open
Abstract
Activation of the checkpoint protein Tel1 requires the Mre11–Rad50–Xrs2 (MRX) complex, which recruits Tel1 at DNA double-strand breaks (DSBs) through direct interaction between Tel1 and Xrs2. However, in vitro Tel1 activation by MRX requires ATP binding to Rad50, suggesting a role also for the MR subcomplex in Tel1 activation. Here we describe two separation-of-functions alleles, mre11-S499P and rad50-A78T, which we show to specifically affect Tel1 activation without impairing MRX functions in DSB repair. Both Mre11-S499P and Rad50-A78T reduce Tel1–MRX interaction leading to poor Tel1 association at DSBs and consequent loss of Tel1 activation. The Mre11-S499P variant reduces Mre11–Rad50 interaction, suggesting an important role for MR complex formation in Tel1 activation. Molecular dynamics simulations show that the wild type MR subcomplex bound to ATP lingers in a tightly ‘closed’ conformation, while ADP presence leads to the destabilization of Rad50 dimer and of Mre11–Rad50 association, both events being required for MR conformational transition to an open state. By contrast, MRA78T undertakes complex opening even if Rad50 is bound to ATP, indicating that defective Tel1 activation caused by MRA78T results from destabilization of the ATP-bound conformational state.
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Affiliation(s)
- Corinne Cassani
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano - Bicocca, 20126 Milano, Italy
| | - Jacopo Vertemara
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano - Bicocca, 20126 Milano, Italy
| | - Matteo Bassani
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano - Bicocca, 20126 Milano, Italy
| | - Antonio Marsella
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano - Bicocca, 20126 Milano, Italy
| | - Renata Tisi
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano - Bicocca, 20126 Milano, Italy
| | - Giuseppe Zampella
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano - Bicocca, 20126 Milano, Italy
| | - Maria Pia Longhese
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano - Bicocca, 20126 Milano, Italy
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40
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Walker AK, Na J, Browning L, Humayun-Zakaria N, Zeegers MP, Cheng K, James ND, Bryan RT, Arnold R, Kiltie AE. MRE11A Isoform Expression Associated with Outcome Following Radiotherapy in Muscle-Invasive Bladder Cancer does not Alter Cell Survival and DNA Double-Strand Break Repair Following Ionising Radiation. Bladder Cancer 2019; 5:147-157. [PMID: 31942442 PMCID: PMC6949534 DOI: 10.3233/blc-190209] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
BACKGROUND DNA double strand breaks are the cytotoxic lesions produced by ionising radiation. Critical for the repair of these lesions is the DNA damage response protein MRE11 which, in a complex with RAD50 and NBS1, mediates DNA damage signalling and double-strand break repair. We previously found the presence of an MRE11 germline single nucleotide polymorphism (SNP), rs1805363 (G > A), to be associated with poor outcome following radiotherapy (RT) and increased expression of MRE11 isoform 2 in a limited panel of bladder cancer cell lines and tumours. OBJECTIVES To look for further evidence in support of the SNP/isoform association in a larger panel of germline and tumour samples donated by patients diagnosed with invasive bladder cancer, and to test the hypothesis that bladder cancer cells expressing MRE11 isoform 2 would be more radio resistant than cells expressing MRE11 isoform 1. METHODS Germline DNA from 189 patients with invasive bladder cancer (141 T2, 48 T1) was genotyped for the rs1805363 G > A SNP. Loss of heterozygosity was determined by genotyping tumour DNA in 17GA germline patients. The Cancer Genome Atlas was mined to correlate presence of the GA germline genotype with MRE11 isoform expression. We used colony formation assays and γH2AX foci kinetics after ionising radiation in RT112 MRE11 knockdown cells expressing ectopic MRE11 isoform 1 or 2. RESULTS Of the 189 germline DNA samples, 22 contained both the A minor allele and G major allele with the remaining wild type containing only the G major allele. LOH was identified in seven of 17 available tumour samples. Tumour MRE11 isoform 2 expression was found to be significantly higher (p = 0.007) in patients's samples containing the A minor allele compared to those with only the G major allele (n = 23). In the TCGA database we found 16% (66 out of 406) of bladder tumours heterozygous for the SNP and only two homozygous, and a significant relative increase of isoform 2 usage (p = 0.017). We identified no significant difference in radio sensitivity between bladder cancer cells expressing either MRE11 isoform. CONCLUSIONS In this study the MRE11 isoform 2 was not found to be associated with increased cellular sensitivity to radiation. We conclude that the previously reported association between the germline rs1805363 SNP and poor survival in MIBC patients following RT is unlikely to be related to the DNA damage response function of MRE11 isoform 2.
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Affiliation(s)
- Alexandra K. Walker
- CRUK/MRC Oxford Institute for Radiation Oncology, University of Oxford, Oxford, UK
| | - Juri Na
- CRUK/MRC Oxford Institute for Radiation Oncology, University of Oxford, Oxford, UK
| | - Lisa Browning
- Department of Cellular Pathology, Oxford University Hospitals NHS Foundation Trust, John Radcliffe Hospital, and NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Nada Humayun-Zakaria
- The Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, UK
| | - Maurice P. Zeegers
- NUTRIM School for Nutrition and Translational Research in Metabolism and CAPHRI Care and Public Health Research Institute, Maastricht University, Maastricht, the Netherlands
| | - K.K. Cheng
- The Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, UK
| | - Nicholas D. James
- The Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, UK
| | - Richard T. Bryan
- The Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, UK
| | - Roland Arnold
- The Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, UK
| | - Anne E. Kiltie
- CRUK/MRC Oxford Institute for Radiation Oncology, University of Oxford, Oxford, UK
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41
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Casari E, Rinaldi C, Marsella A, Gnugnoli M, Colombo CV, Bonetti D, Longhese MP. Processing of DNA Double-Strand Breaks by the MRX Complex in a Chromatin Context. Front Mol Biosci 2019; 6:43. [PMID: 31231660 PMCID: PMC6567933 DOI: 10.3389/fmolb.2019.00043] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 05/21/2019] [Indexed: 12/24/2022] Open
Abstract
DNA double-strand breaks (DSBs) are highly cytotoxic lesions that must be repaired to ensure genomic stability and avoid cell death. The cellular response to DSBs is initiated by the evolutionarily conserved Mre11-Rad50-Xrs2/NBS1 (MRX/MRN) complex that has structural and catalytic functions. Furthermore, it is responsible for DSB signaling through the activation of the checkpoint kinase Tel1/ATM. Here, we review functions and regulation of the MRX/MRN complex in DSB processing in a chromatin context, as well as its interplay with Tel1/ATM.
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Affiliation(s)
| | | | | | | | | | | | - Maria Pia Longhese
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Milan, Italy
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42
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Hailemariam S, Kumar S, Burgers PM. Activation of Tel1 ATM kinase requires Rad50 ATPase and long nucleosome-free DNA but no DNA ends. J Biol Chem 2019; 294:10120-10130. [PMID: 31073030 DOI: 10.1074/jbc.ra119.008410] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Revised: 05/07/2019] [Indexed: 12/13/2022] Open
Abstract
In Saccharomyces cerevisiae, Tel1 protein kinase, the ortholog of human ataxia telangiectasia-mutated (ATM), is activated in response to DNA double-strand breaks. Biochemical studies with human ATM and genetic studies in yeast suggest that recruitment and activation of Tel1ATM depends on the heterotrimeric MRXMRN complex, composed of Mre11, Rad50, and Xrs2 (human Nbs1). However, the mechanism of activation of Tel1 by MRX remains unclear, as does the role of effector DNA. Here we demonstrate that dsDNA and MRX activate Tel1 synergistically. Although minimal activation was observed with 80-mer duplex DNA, the optimal effector for Tel1 activation is long, nucleosome-free DNA. However, there is no requirement for DNA double-stranded termini. The ATPase activity of Rad50 is critical for activation. In addition to DNA and Rad50, either Mre11 or Xrs2, but not both, is also required. Each of the three MRX subunits shows a physical association with Tel1. Our study provides a model of how the individual subunits of MRX and DNA regulate Tel1 kinase activity.
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Affiliation(s)
- Sarem Hailemariam
- From the Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Sandeep Kumar
- From the Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Peter M Burgers
- From the Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110
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43
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Myler LR, Soniat MM, Zhang X, Deshpande RA, Paull TT, Finkelstein IJ. Purification and Biophysical Characterization of the Mre11-Rad50-Nbs1 Complex. Methods Mol Biol 2019; 2004:269-287. [PMID: 31147924 PMCID: PMC6667175 DOI: 10.1007/978-1-4939-9520-2_20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The Mre11-Rad50-Nbs1 (MRN) complex coordinates the repair of DNA double-strand breaks, replication fork restart, meiosis, class-switch recombination, and telomere maintenance. As such, MRN is an essential molecular machine that has homologs in all organisms of life, from bacteriophage to humans. In human cells, MRN is a >500 kDa multifunctional complex that encodes DNA binding, ATPase, and both endonuclease and exonuclease activities. MRN also forms larger assemblies and interacts with multiple DNA repair and replication factors. The enzymatic properties of MRN have been the subject of intense research for over 20 years, and more recently, single-molecule biophysics studies are beginning to probe its many biochemical activities. Here, we describe the methods used to overexpress, fluorescently label, and visualize MRN and its activities on single molecules of DNA.
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Affiliation(s)
- Logan R Myler
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX, USA
| | - Michael M Soniat
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX, USA
- Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, TX, USA
| | - Xiaoming Zhang
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX, USA
- The Howard Hughes Medical Institute, The University of Texas at Austin, Austin, TX, USA
| | - Rajashree A Deshpande
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX, USA
- The Howard Hughes Medical Institute, The University of Texas at Austin, Austin, TX, USA
| | - Tanya T Paull
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX, USA
- The Howard Hughes Medical Institute, The University of Texas at Austin, Austin, TX, USA
| | - Ilya J Finkelstein
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX, USA.
- Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, TX, USA.
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44
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Abstract
DNA double-strand breaks (DSBs) are a potentially lethal DNA lesions that disrupt both the physical and genetic continuity of the DNA duplex. Homologous recombination (HR) is a universally conserved genome maintenance pathway that initiates via nucleolytic processing of the broken DNA ends (resection). Eukaryotic DNA resection is catalyzed by the resectosome-a multicomponent molecular machine consisting of the nucleases DNA2 or Exonuclease 1 (EXO1), Bloom's helicase (BLM), the MRE11-RAD50-NBS1 (MRN) complex, and additional regulatory factors. Here, we describe methods for purification and single-molecule imaging and analysis of EXO1, DNA2, and BLM. We also describe how to adapt resection assays to the high-throughput single-molecule DNA curtain assay. By organizing hundreds of individual molecules on the surface of a microfluidic flowcell, DNA curtains visualize protein complexes with the required spatial and temporal resolution to resolve the molecular choreography during critical DNA-processing reactions.
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45
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Oh J, Symington LS. Role of the Mre11 Complex in Preserving Genome Integrity. Genes (Basel) 2018; 9:E589. [PMID: 30501098 PMCID: PMC6315862 DOI: 10.3390/genes9120589] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 11/26/2018] [Accepted: 11/27/2018] [Indexed: 12/12/2022] Open
Abstract
DNA double-strand breaks (DSBs) are hazardous lesions that threaten genome integrity and cell survival. The DNA damage response (DDR) safeguards the genome by sensing DSBs, halting cell cycle progression and promoting repair through either non-homologous end joining (NHEJ) or homologous recombination (HR). The Mre11-Rad50-Xrs2/Nbs1 (MRX/N) complex is central to the DDR through its structural, enzymatic, and signaling roles. The complex tethers DNA ends, activates the Tel1/ATM kinase, resolves protein-bound or hairpin-capped DNA ends, and maintains telomere homeostasis. In addition to its role at DSBs, MRX/N associates with unperturbed replication forks, as well as stalled replication forks, to ensure complete DNA synthesis and to prevent chromosome rearrangements. Here, we summarize the significant progress made in characterizing the MRX/N complex and its various activities in chromosome metabolism.
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Affiliation(s)
- Julyun Oh
- Biological Sciences Program, Columbia University, New York, NY 10027, USA.
- Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY 10032, USA.
| | - Lorraine S Symington
- Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY 10032, USA.
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46
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Johnson TE, Lee JH, Myler LR, Zhou Y, Mosley TJ, Yang SH, Uprety N, Kim J, Paull TT. Homeodomain Proteins Directly Regulate ATM Kinase Activity. Cell Rep 2018; 24:1471-1483. [PMID: 30089259 PMCID: PMC6127865 DOI: 10.1016/j.celrep.2018.06.089] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2018] [Revised: 04/18/2018] [Accepted: 06/20/2018] [Indexed: 12/17/2022] Open
Abstract
Ataxia-telangiectasia mutated (ATM) is a serine/threonine kinase that coordinates the response to DNA double-strand breaks and oxidative stress. NKX3.1, a prostate-specific transcription factor, was recently shown to directly stimulate ATM kinase activity through its highly conserved homeodomain. Here, we show that other members of the homeodomain family can also regulate ATM kinase activity. We found that six representative homeodomain proteins (NKX3.1, NKX2.2, TTF1, NKX2.5, HOXB7, and CDX2) physically and functionally interact with ATM and with the Mre11-Rad50-Nbs1 (MRN) complex that activates ATM in combination with DNA double-strand breaks. The binding between homeodomain proteins and ATM stimulates oxidation-induced ATM activation in vitro but inhibits ATM kinase activity in the presence of MRN and DNA and in human cells. These findings suggest that many tissue-specific homeodomain proteins may regulate ATM activity during development and differentiation and that this is a unique mechanism for the control of the DNA damage response.
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Affiliation(s)
- Tanya E Johnson
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712, USA; Howard Hughes Medical Institute, The University of Texas at Austin, Austin, TX 78712, USA
| | - Ji-Hoon Lee
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712, USA; Howard Hughes Medical Institute, The University of Texas at Austin, Austin, TX 78712, USA
| | - Logan R Myler
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712, USA; Howard Hughes Medical Institute, The University of Texas at Austin, Austin, TX 78712, USA
| | - Yi Zhou
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712, USA
| | - Trenell J Mosley
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Soo-Hyun Yang
- College of Natural Sciences, The University of Texas at Austin, Austin, TX 78712, USA
| | - Nadima Uprety
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712, USA
| | - Jonghwan Kim
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712, USA
| | - Tanya T Paull
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712, USA; Howard Hughes Medical Institute, The University of Texas at Austin, Austin, TX 78712, USA.
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47
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Paull TT. 20 Years of Mre11 Biology: No End in Sight. Mol Cell 2018; 71:419-427. [PMID: 30057197 DOI: 10.1016/j.molcel.2018.06.033] [Citation(s) in RCA: 95] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 05/18/2018] [Accepted: 06/21/2018] [Indexed: 01/01/2023]
Abstract
The Mre11 nuclease has been the subject of intensive investigation for the past 20 years because of the central role that Mre11/Rad50 complexes play in genome maintenance. The last two decades of work on this complex has led to a much deeper understanding of the structure, biochemical activities, and regulation of Mre11/Rad50 complexes from archaea, bacteria, and eukaryotic cells. This review will discuss some of the important findings over recent years that have illuminated roles for the Mre11 nuclease in these different contexts as well as the insights from structural biology that have helped us to understand its mechanisms of action.
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Affiliation(s)
- Tanya T Paull
- Howard Hughes Medical Institute; Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA.
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48
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Abstract
The ATM gene is mutated in the syndrome, ataxia-telangiectasia (AT), which is characterized by predisposition to cancer. Patients with AT have an elevated risk of breast and brain tumors Carrying mutations in ATM, patients with AT have an elevated risk of breast and brain tumors. An increased frequency of ATM mutations has also been reported in patients with breast and brain tumors; however, the magnitude of this risk remains uncertain. With the exception of a few common mutations, the spectrum of ATM alterations is heterogeneous in diverse populations, and appears to be remarkably dependent on the ethnicity of patients. This review aims to provide an easily accessible summary of common variants in different populations which could be useful in ATM screening programs. In addition, we have summarized previous research on ATM, including its molecular functions. We attempt to demonstrate the significance of ATM in exploration of breast and brain tumors and its potential as a therapeutic target.
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Affiliation(s)
- Mehrdad Asghari Estiar
- Department of Medical Genetics, School of Medicine, Tehran University of Medical Sciences, Tehran 14155-6447, Iran
| | - Parvin Mehdipour
- Department of Medical Genetics, School of Medicine, Tehran University of Medical Sciences, Tehran 14155-6447, Iran
- Parvin Mehdipour
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49
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Limbo O, Yamada Y, Russell P. Mre11-Rad50-dependent activity of ATM/Tel1 at DNA breaks and telomeres in the absence of Nbs1. Mol Biol Cell 2018; 29:1389-1399. [PMID: 29851556 PMCID: PMC5994899 DOI: 10.1091/mbc.e17-07-0470] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The Mre11-Rad50-Nbs1 (MRN) protein complex and ATM/Tel1 kinase protect genome integrity through their functions in DNA double-strand break (DSB) repair, checkpoint signaling, and telomere maintenance. Nbs1 has a conserved C-terminal motif that binds ATM/Tel1, but the full extent and significance of ATM/Tel1 interactions with MRN are unknown. Here, we show that Tel1 overexpression bypasses the requirement for Nbs1 in DNA damage signaling and telomere maintenance. These activities require Mre11-Rad50, which localizes to DSBs and bind Tel1 in the absence of Nbs1. Fusion of the Tel1-binding motif of Nbs1 to Mre11 is sufficient to restore Tel1 signaling in nbs1Δ cells. Tel1 overexpression does not restore Tel1 signaling in cells carrying the rad50-I1192W mutation, which impairs the ability of Mre11-Rad50 to form the ATP-bound closed conformation. From these findings, we propose that Tel1 has a high-affinity interaction with the C-terminus of Nbs1 and a low-affinity association with Mre11-Rad50, which together accomplish efficient localization and activation of Tel1 at DSBs and telomeres.
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Affiliation(s)
- Oliver Limbo
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037
| | - Yoshiki Yamada
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037
| | - Paul Russell
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037
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Lee JH, Mand MR, Kao CH, Zhou Y, Ryu SW, Richards AL, Coon JJ, Paull TT. ATM directs DNA damage responses and proteostasis via genetically separable pathways. Sci Signal 2018; 11:eaan5598. [PMID: 29317520 PMCID: PMC5898228 DOI: 10.1126/scisignal.aan5598] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The protein kinase ATM is a master regulator of the DNA damage response but also responds directly to oxidative stress. Loss of ATM causes ataxia telangiectasia, a neurodegenerative disorder with pleiotropic symptoms that include cerebellar dysfunction, cancer, diabetes, and premature aging. We genetically separated the activation of ATM by DNA damage from that by oxidative stress using separation-of-function mutations. We found that deficient activation of ATM by the Mre11-Rad50-Nbs1 complex and DNA double-strand breaks resulted in loss of cell viability, checkpoint activation, and DNA end resection in response to DNA damage. In contrast, loss of oxidative activation of ATM had minimal effects on DNA damage-related outcomes but blocked ATM-mediated initiation of checkpoint responses after oxidative stress and resulted in deficiencies in mitochondrial function and autophagy. In addition, expression of a variant ATM incapable of activation by oxidative stress resulted in widespread protein aggregation. These results indicate a direct relationship between the mechanism of ATM activation and its effects on cellular metabolism and DNA damage responses in human cells and implicate ATM in the control of protein homeostasis.
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Affiliation(s)
- Ji-Hoon Lee
- Howard Hughes Medical Institute, Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Michael R Mand
- Howard Hughes Medical Institute, Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Chung-Hsuan Kao
- Howard Hughes Medical Institute, Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Yi Zhou
- Howard Hughes Medical Institute, Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Seung W Ryu
- Howard Hughes Medical Institute, Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Alicia L Richards
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Joshua J Coon
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Tanya T Paull
- Howard Hughes Medical Institute, Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA.
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