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Silva JPL, Donaires FS, Gutierrez-Rodrigues F, Martins DJ, Carvalho VS, Santana BA, Cunha RLG, Kajigaya S, Menck CFM, Young NS, Kjeldsen E, Calado RT. RecQ helicase expression in patients with telomeropathies. Mol Biol Rep 2024; 51:754. [PMID: 38874681 DOI: 10.1007/s11033-024-09678-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Accepted: 05/24/2024] [Indexed: 06/15/2024]
Abstract
BACKGROUND Telomeropathies are a group of inherited disorders caused by germline pathogenic variants in genes involved in telomere maintenance, resulting in excessive telomere attrition that affects several tissues, including hematopoiesis. RecQ and RTEL1 helicases contribute to telomere maintenance by unwinding telomeric structures such as G-quadruplexes (G4), preventing replication defects. Germline RTEL1 variants also are etiologic in telomeropathies. METHODS AND RESULTS Here we investigated the expression of RecQ (RECQL1, BLM, WRN, RECQL4, and RECQL5) and RTEL1 helicase genes in peripheral blood mononuclear cells (PBMCs) from human telomeropathy patients. The mRNA expression levels of all RecQ helicases, but not RTEL1, were significantly downregulated in patients' primary cells. Reduced RecQ expression was not attributable to cell proliferative exhaustion, as RecQ helicases were not attenuated in T cells exhausted in vitro. An additional fifteen genes involved in DNA damage repair and RecQ functional partners also were downregulated in the telomeropathy cells. CONCLUSION These findings indicate that the expression of RecQ helicases and functional partners involved in DNA repair is downregulated in PBMCs of telomeropathy patients.
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Affiliation(s)
- João Paulo L Silva
- Department of Medical Imaging, Hematology, and Oncology, Ribeirão Preto Medical School, University of São Paulo, Av. Bandeirantes, 3900 - 7 o andar, sala 743 - HCRP, Ribeirão Preto, SP, 14049-900, Brazil
| | - Flávia S Donaires
- Department of Medical Imaging, Hematology, and Oncology, Ribeirão Preto Medical School, University of São Paulo, Av. Bandeirantes, 3900 - 7 o andar, sala 743 - HCRP, Ribeirão Preto, SP, 14049-900, Brazil
| | | | - Davi J Martins
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Vinicius S Carvalho
- Department of Medical Imaging, Hematology, and Oncology, Ribeirão Preto Medical School, University of São Paulo, Av. Bandeirantes, 3900 - 7 o andar, sala 743 - HCRP, Ribeirão Preto, SP, 14049-900, Brazil
| | - Barbara A Santana
- Department of Medical Imaging, Hematology, and Oncology, Ribeirão Preto Medical School, University of São Paulo, Av. Bandeirantes, 3900 - 7 o andar, sala 743 - HCRP, Ribeirão Preto, SP, 14049-900, Brazil
| | - Renato L G Cunha
- Department of Medical Imaging, Hematology, and Oncology, Ribeirão Preto Medical School, University of São Paulo, Av. Bandeirantes, 3900 - 7 o andar, sala 743 - HCRP, Ribeirão Preto, SP, 14049-900, Brazil
| | - Sachiko Kajigaya
- Hematology Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Carlos F M Menck
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Neal S Young
- Hematology Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Eigil Kjeldsen
- Department of Hematology, Aarhus University Hospital, Aarhus, Denmark
| | - Rodrigo T Calado
- Department of Medical Imaging, Hematology, and Oncology, Ribeirão Preto Medical School, University of São Paulo, Av. Bandeirantes, 3900 - 7 o andar, sala 743 - HCRP, Ribeirão Preto, SP, 14049-900, Brazil.
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Sato K, Knipscheer P. G-quadruplex resolution: From molecular mechanisms to physiological relevance. DNA Repair (Amst) 2023; 130:103552. [PMID: 37572578 DOI: 10.1016/j.dnarep.2023.103552] [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: 05/24/2023] [Revised: 07/29/2023] [Accepted: 08/01/2023] [Indexed: 08/14/2023]
Abstract
Guanine-rich DNA sequences can fold into stable four-stranded structures called G-quadruplexes or G4s. Research in the past decade demonstrated that G4 structures are widespread in the genome and prevalent in regulatory regions of actively transcribed genes. The formation of G4s has been tightly linked to important biological processes including regulation of gene expression and genome maintenance. However, they can also pose a serious threat to genome integrity especially by impeding DNA replication, and G4-associated somatic mutations have been found accumulated in the cancer genomes. Specialised DNA helicases and single stranded DNA binding proteins that can resolve G4 structures play a crucial role in preventing genome instability. The large variety of G4 unfolding proteins suggest the presence of multiple G4 resolution mechanisms in cells. Recently, there has been considerable progress in our detailed understanding of how G4s are resolved, especially during DNA replication. In this review, we first discuss the current knowledge of the genomic G4 landscapes and the impact of G4 structures on DNA replication and genome integrity. We then describe the recent progress on the mechanisms that resolve G4 structures and their physiological relevance. Finally, we discuss therapeutic opportunities to target G4 structures.
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Affiliation(s)
- Koichi Sato
- Oncode Institute, Hubrecht Institute-KNAW & University Medical Center Utrecht, Utrecht, the Netherlands.
| | - Puck Knipscheer
- Oncode Institute, Hubrecht Institute-KNAW & University Medical Center Utrecht, Utrecht, the Netherlands; Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands.
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Lee J, Zhang J, Flanagan M, Martinez JA, Cunniff C, Kucine N, Lu AT, Haghani A, Gordevičius J, Horvath S, Chang VY. Bloom syndrome patients and mice display accelerated epigenetic aging. Aging Cell 2023; 22:e13964. [PMID: 37594403 PMCID: PMC10577546 DOI: 10.1111/acel.13964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 07/26/2023] [Accepted: 08/01/2023] [Indexed: 08/19/2023] Open
Abstract
Bloom syndrome (BSyn) is an autosomal recessive disorder caused by variants in the BLM gene, which is involved in genome stability. Patients with BSyn present with poor growth, sun sensitivity, mild immunodeficiency, diabetes, and increased risk of cancer, most commonly leukemias. Interestingly, patients with BSyn do not have other signs of premature aging such as early, progressive hair loss and cataracts. We set out to determine epigenetic age in BSyn, which can be a better predictor of health and disease over chronological age. Our results show for the first time that patients with BSyn have evidence of accelerated epigenetic aging across several measures in blood lymphocytes, as compared to carriers. Additionally, homozygous Blm mice exhibit accelerated methylation age in multiple tissues, including brain, blood, kidney, heart, and skin, according to the brain methylation clock. Overall, we find that Bloom syndrome is associated with accelerated epigenetic aging effects in multiple tissues and more generally a strong effect on CpG methylation levels.
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Affiliation(s)
- Jamie Lee
- Division of Pediatric Hematology and OncologyUCLALos AngelesCaliforniaUSA
| | - Joshua Zhang
- Department of Human GeneticsUCLALos AngelesCaliforniaUSA
| | - Maeve Flanagan
- Department of PediatricsWeill Cornell Medical CollegeNew YorkNew YorkUSA
| | - Julian A. Martinez
- Department of Human GeneticsUCLALos AngelesCaliforniaUSA
- Division of Medical GeneticsUCLALos AngelesCaliforniaUSA
- Department of PsychiatryUCLALos AngelesCaliforniaUSA
| | | | - Nicole Kucine
- Department of PediatricsWeill Cornell Medical CollegeNew YorkNew YorkUSA
| | - Ake T. Lu
- Department of Human GeneticsUCLALos AngelesCaliforniaUSA
- Altos LabsSan DiegoCaliforniaUSA
| | - Amin Haghani
- Department of Human GeneticsUCLALos AngelesCaliforniaUSA
- Altos LabsSan DiegoCaliforniaUSA
| | | | - Steve Horvath
- Department of Human GeneticsUCLALos AngelesCaliforniaUSA
- Altos LabsSan DiegoCaliforniaUSA
| | - Vivian Y. Chang
- Division of Pediatric Hematology and OncologyUCLALos AngelesCaliforniaUSA
- Children's Discovery and Innovation InstituteUCLALos AngelesCaliforniaUSA
- Jonsson Comprehensive Cancer CenterUCLALos AngelesCaliforniaUSA
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Zade NH, Khattar E. POT1 mutations cause differential effects on telomere length leading to opposing disease phenotypes. J Cell Physiol 2023; 238:1237-1255. [PMID: 37183325 DOI: 10.1002/jcp.31034] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2023] [Revised: 03/28/2023] [Accepted: 04/17/2023] [Indexed: 05/16/2023]
Abstract
The protection of telomere protein (POT1) is a telomere-binding protein and is an essential component of the six-membered shelterin complex, which is associated with the telomeres. POT1 directly binds to the 3' single-stranded telomeric overhang and prevents the activation of DNA damage response at telomeres thus preventing the telomere-telomere fusions and genomic instability. POT1 also plays a pivotal role in maintaining telomere length by regulating telomerase-mediated telomere elongation. Mutations in POT1 proteins result in three different telomere phenotypes, which include long, short, or aberrant telomere length. Long telomeres predispose individuals to cancer, while short or aberrant telomere phenotypes result in pro-aging diseases referred to as telomeropathies. Here, we review the function of POT1 proteins in telomere length hemostasis and how the spectrum of mutations reported in POT1 can be segregated toward developing very distinct disease phenotypes of cancer and telomeropathies.
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Affiliation(s)
- Nikita Harish Zade
- Sunandan Divatia School of Science, SVKM's NMIMS (Deemed to be) University, Mumbai, India
| | - Ekta Khattar
- Sunandan Divatia School of Science, SVKM's NMIMS (Deemed to be) University, Mumbai, India
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Vijay Kumar MJ, Morales R, Tsvetkov AS. G-quadruplexes and associated proteins in aging and Alzheimer's disease. FRONTIERS IN AGING 2023; 4:1164057. [PMID: 37323535 PMCID: PMC10267416 DOI: 10.3389/fragi.2023.1164057] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2023] [Accepted: 05/17/2023] [Indexed: 06/17/2023]
Abstract
Aging is a prominent risk factor for many neurodegenerative disorders, such as Alzheimer's disease (AD). Alzheimer's disease is characterized by progressive cognitive decline, memory loss, and neuropsychiatric and behavioral symptoms, accounting for most of the reported dementia cases. This disease is now becoming a major challenge and burden on modern society, especially with the aging population. Over the last few decades, a significant understanding of the pathophysiology of AD has been gained by studying amyloid deposition, hyperphosphorylated tau, synaptic dysfunction, oxidative stress, calcium dysregulation, and neuroinflammation. This review focuses on the role of non-canonical secondary structures of DNA/RNA G-quadruplexes (G4s, G4-DNA, and G4-RNA), G4-binding proteins (G4BPs), and helicases, and their roles in aging and AD. Being critically important for cellular function, G4s are involved in the regulation of DNA and RNA processes, such as replication, transcription, translation, RNA localization, and degradation. Recent studies have also highlighted G4-DNA's roles in inducing DNA double-strand breaks that cause genomic instability and G4-RNA's participation in regulating stress granule formation. This review emphasizes the significance of G4s in aging processes and how their homeostatic imbalance may contribute to the pathophysiology of AD.
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Affiliation(s)
- M. J. Vijay Kumar
- The Department of Neurology, The University of Texas McGovern Medical School at Houston, Houston, TX, United States
| | - Rodrigo Morales
- The Department of Neurology, The University of Texas McGovern Medical School at Houston, Houston, TX, United States
- Centro Integrativo de Biologia y Quimica Aplicada (CIBQA), Universidad Bernardo O’Higgins, Santiago, Chile
| | - Andrey S. Tsvetkov
- The Department of Neurology, The University of Texas McGovern Medical School at Houston, Houston, TX, United States
- The University of Texas Graduate School of Biomedical Sciences, Houston, TX, United States
- UTHealth Consortium on Aging, The University of Texas McGovern Medical School, Houston, TX, United States
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Kołat D, Zhao LY, Kciuk M, Płuciennik E, Kałuzińska-Kołat Ż. AP-2δ Is the Most Relevant Target of AP-2 Family-Focused Cancer Therapy and Affects Genome Organization. Cells 2022; 11:cells11244124. [PMID: 36552887 PMCID: PMC9776946 DOI: 10.3390/cells11244124] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 11/26/2022] [Accepted: 12/15/2022] [Indexed: 12/24/2022] Open
Abstract
Formerly hailed as "undruggable" proteins, transcription factors (TFs) are now under investigation for targeted therapy. In cancer, this may alter, inter alia, immune evasion or replicative immortality, which are implicated in genome organization, a process that accompanies multi-step tumorigenesis and which frequently develops in a non-random manner. Still, targeting-related research on some TFs is scarce, e.g., among AP-2 proteins, which are known for their altered functionality in cancer and prognostic importance. Using public repositories, bioinformatics tools, and RNA-seq data, the present study examined the ligandability of all AP-2 members, selecting the best one, which was investigated in terms of mutations, targets, co-activators, correlated genes, and impact on genome organization. AP-2 proteins were found to have the conserved "TF_AP-2" domain, but manifested different binding characteristics and evolution. Among them, AP-2δ has not only the highest number of post-translational modifications and extended strands but also contains a specific histidine-rich region and cleft that can receive a ligand. Uterine, colon, lung, and stomach tumors are most susceptible to AP-2δ mutations, which also co-depend with cancer hallmark genes and drug targets. Considering AP-2δ targets, some of them were located proximally in the spatial genome or served as co-factors of the genes regulated by AP-2δ. Correlation and functional analyses suggested that AP-2δ affects various processes, including genome organization, via its targets; this has been eventually verified in lung adenocarcinoma using expression and immunohistochemistry data of chromosomal conformation-related genes. In conclusion, AP-2δ affects chromosomal conformation and is the most appropriate target for cancer therapy focused on the AP-2 family.
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Affiliation(s)
- Damian Kołat
- Department of Experimental Surgery, Medical University of Lodz, 90-136 Lodz, Poland
- Correspondence:
| | - Lin-Yong Zhao
- Gastric Cancer Center and Laboratory of Gastric Cancer, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, and Collaborative Innovation Centre for Biotherapy, Chengdu 610041, China
| | - Mateusz Kciuk
- Department of Molecular Biotechnology and Genetics, University of Lodz, 90-237 Lodz, Poland
- Doctoral School of Exact and Natural Sciences, University of Lodz, 90-237 Lodz, Poland
| | - Elżbieta Płuciennik
- Department of Functional Genomics, Medical University of Lodz, 90-752 Lodz, Poland
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7
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Research on Werner Syndrome: Trends from Past to Present and Future Prospects. Genes (Basel) 2022; 13:genes13101802. [PMID: 36292687 PMCID: PMC9601476 DOI: 10.3390/genes13101802] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 10/02/2022] [Accepted: 10/04/2022] [Indexed: 11/17/2022] Open
Abstract
A rare and autosomal recessive premature aging disorder, Werner syndrome (WS) is characterized by the early onset of aging-associated diseases, including shortening stature, alopecia, bilateral cataracts, skin ulcers, diabetes, osteoporosis, arteriosclerosis, and chromosomal instability, as well as cancer predisposition. WRN, the gene responsible for WS, encodes DNA helicase with a 3′ to 5′ exonuclease activity, and numerous studies have revealed that WRN helicase is involved in the maintenance of chromosome stability through actions in DNA, e.g., DNA replication, repair, recombination, and epigenetic regulation via interaction with DNA repair factors, telomere-binding proteins, histone modification enzymes, and other DNA metabolic factors. However, although these efforts have elucidated the cellular functions of the helicase in cell lines, they have not been linked to the treatment of the disease. Life expectancy has improved for WS patients over the past three decades, and it is hoped that a fundamental treatment for the disease will be developed. Disease-specific induced pluripotent stem (iPS) cells have been established, and these are expected to be used in drug discovery and regenerative medicine for WS patients. In this article, we review trends in research to date and present some perspectives on WS research with regard to the application of pluripotent stem cells. Furthermore, the elucidation of disease mechanisms and drug discovery utilizing the vast amount of scientific data accumulated to date will be discussed.
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8
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Low GKM, Ting APL, Fok EDZ, Gopalakrishnan K, Zeegers D, Khaw AK, Jayapal M, Martinez-Lopez W, Hande MP. Role of Xeroderma pigmentosum D (XPD) protein in genome maintenance in human cells under oxidative stress. MUTATION RESEARCH. GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2022; 876-877:503444. [PMID: 35483790 DOI: 10.1016/j.mrgentox.2022.503444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 12/29/2021] [Accepted: 01/10/2022] [Indexed: 06/14/2023]
Abstract
Xeroderma pigmentosum D (XPD) protein plays a pivotal role in the nucleotide excision repair pathway. XPD unwinds the local area of the damaged DNA by virtue of constituting transcription factor II H (TFIIH) and is important not only for repair but also for basal transcription. Although cells deficient in XPD have shown to be defective in oxidative base-lesion repair, the effects of the oxidative assault on primary fibroblasts from patients suffering from Xeroderma Pigmentosum D have not been fully explored. Therefore, we sought to investigate the role of XPD in oxidative DNA damage-repair by treating primary fibroblasts derived from a patient suffering from Xeroderma Pigmentosum D, with hydrogen peroxide. Our results show dose-dependent increase in genotoxicity with minimal effect on cytotoxicity with H2O2 in XPD deficient cells compared to control cells. XPD deficient cells displayed increased susceptibility and reduced repair capacity when subjected to DNA damage induced by oxidative stress. XPD deficient fibroblasts exhibited increased telomeric loss after H2O2 treatment. In addition, we demonstrated that chronic oxidative stress induced accelerated premature senescence characteristics. Gene expression profiling revealed alterations in genes involved in transcription and nucleotide metabolisms, as well as in cellular and cell cycle processes in a more significant way than in other pathways. This study highlights the role of XPD in the repair of oxidative stress and telomere maintenance. Lack of functional XPD seems to increase the susceptibility of oxidative stress-induced genotoxicity while retaining cell viability posing as a potential cancer risk factor of Xeroderma Pigmentosum D patients.
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Affiliation(s)
- Grace Kah Mun Low
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Aloysius Poh Leong Ting
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Edwin Dan Zhihao Fok
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Kalpana Gopalakrishnan
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Dimphy Zeegers
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Aik Kia Khaw
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Manikandan Jayapal
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Wilner Martinez-Lopez
- Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, Uruguay; Associate Unit on Genomic Stability, Faculty of Medicine, University of the Republic (UdelaR), Montevideo, Uruguay; Vellore Institute of Technology, Vellore, India
| | - M Prakash Hande
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; Vellore Institute of Technology, Vellore, India; Mangalore University, India.
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Hsu TY, Hsu LN, Chen SY, Juang BT. MUT-7 Provides Molecular Insight into the Werner Syndrome Exonuclease. Cells 2021; 10:cells10123457. [PMID: 34943966 PMCID: PMC8700014 DOI: 10.3390/cells10123457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 12/01/2021] [Accepted: 12/05/2021] [Indexed: 11/24/2022] Open
Abstract
Werner syndrome (WS) is a rare recessive genetic disease characterized by premature aging. Individuals with this disorder develop normally during childhood, but their physiological conditions exacerbate the aging process in late adolescence. WS is caused by mutation of the human WS gene (WRN), which encodes two main domains, a 3′-5′ exonuclease and a 3′-5′ helicase. Caenorhabditis elegans expresses human WRN orthologs as two different proteins: MUT-7, which has a 3′-5′ exonuclease domain, and C. elegans WRN-1 (CeWRN-1), which has only helicase domains. These unique proteins dynamically regulate olfactory memory in C. elegans, providing insight into the molecular roles of WRN domains in humans. In this review, we specifically focus on characterizing the function of MUT-7 in small interfering RNA (siRNA) synthesis in the cytoplasm and the roles of siRNA in directing nuclear CeWRN-1 loading onto a heterochromatin complex to induce negative feedback regulation. Further studies on the different contributions of the 3′-5′ exonuclease and helicase domains in the molecular mechanism will provide clues to the accelerated aging processes in WS.
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Affiliation(s)
- Tsung-Yuan Hsu
- Department of Biological Science and Technology, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan;
- Department of Cell and Tissue Biology, University of California, 513 Parnassus, San Francisco, CA 94143, USA
| | - Ling-Nung Hsu
- Occupational Safety and Health Office, Fu Jen Catholic University Hospital, New Taipei City 243, Taiwan;
| | - Shih-Yu Chen
- Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan;
| | - Bi-Tzen Juang
- Department of Biological Science and Technology, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan;
- Center for Intelligent Drug Systems and Smart Bio-Devices (IDS2B), National Chiao Tung University, Hsinchu 300, Taiwan
- Correspondence:
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Liu Y, Zhu X, Wang K, Zhang B, Qiu S. The Cellular Functions and Molecular Mechanisms of G-Quadruplex Unwinding Helicases in Humans. Front Mol Biosci 2021; 8:783889. [PMID: 34912850 PMCID: PMC8667583 DOI: 10.3389/fmolb.2021.783889] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 11/02/2021] [Indexed: 01/19/2023] Open
Abstract
G-quadruplexes (G4s) are stable non-canonical secondary structures formed by G-rich DNA or RNA sequences. They play various regulatory roles in many biological processes. It is commonly agreed that G4 unwinding helicases play key roles in G4 metabolism and function, and these processes are closely related to physiological and pathological processes. In recent years, more and more functional and mechanistic details of G4 helicases have been discovered; therefore, it is necessary to carefully sort out the current research efforts. Here, we provide a systematic summary of G4 unwinding helicases from the perspective of functions and molecular mechanisms. First, we provide a general introduction about helicases and G4s. Next, we comprehensively summarize G4 unfolding helicases in humans and their proposed cellular functions. Then, we review their study methods and molecular mechanisms. Finally, we share our perspective on further prospects. We believe this review will provide opportunities for researchers to reach the frontiers in the functions and molecular mechanisms of human G4 unwinding helicases.
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Affiliation(s)
- Yang Liu
- Key laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), Collaborative Innovation Center for Mountain Ecology and Agro-Bioengineering (CICMEAB), College of Life Sciences/Institute of Agro-bioengineering, Guizhou University, Guiyang, China
- College of Basic Medicine, Zunyi Medical University, Zunyi, China
- The Key Laboratory of Fermentation Engineering and Biological Pharmacy of Guizhou Province, Guizhou University, Guiyang, China
- School of Liquor and Food Engineering, Guizhou University, Guiyang, China
| | - Xinting Zhu
- College of Basic Medicine, Zunyi Medical University, Zunyi, China
| | - Kejia Wang
- Key laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), Collaborative Innovation Center for Mountain Ecology and Agro-Bioengineering (CICMEAB), College of Life Sciences/Institute of Agro-bioengineering, Guizhou University, Guiyang, China
- The Key Laboratory of Fermentation Engineering and Biological Pharmacy of Guizhou Province, Guizhou University, Guiyang, China
- School of Liquor and Food Engineering, Guizhou University, Guiyang, China
| | - Bo Zhang
- College of Basic Medicine, Zunyi Medical University, Zunyi, China
| | - Shuyi Qiu
- Key laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), Collaborative Innovation Center for Mountain Ecology and Agro-Bioengineering (CICMEAB), College of Life Sciences/Institute of Agro-bioengineering, Guizhou University, Guiyang, China
- The Key Laboratory of Fermentation Engineering and Biological Pharmacy of Guizhou Province, Guizhou University, Guiyang, China
- School of Liquor and Food Engineering, Guizhou University, Guiyang, China
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11
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Marilovtseva EV, Studitsky VM. Guanine Quadruplexes in Cell Nucleus Metabolism. Mol Biol 2021. [DOI: 10.1134/s0026893321040075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Gudmundsrud R, Skjånes TH, Gilmour BC, Caponio D, Lautrup S, Fang EF. Crosstalk among DNA Damage, Mitochondrial Dysfunction, Impaired Mitophagy, Stem Cell Attrition, and Senescence in the Accelerated Ageing Disorder Werner Syndrome. Cytogenet Genome Res 2021; 161:297-304. [PMID: 34433164 DOI: 10.1159/000516386] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 12/10/2020] [Indexed: 12/13/2022] Open
Abstract
Werner syndrome (WS) is an accelerated ageing disease caused by multiple mutations in the gene encoding the Werner DNA helicase (WRN). The major clinical features of WS include wrinkles, grey hair, osteoporosis, and metabolic phenomena such as atherosclerosis, diabetes, and fatty liver, and resemble those seen in normal ageing, but occur earlier, in middle age. Defective DNA repair resulting from mutations in WRN explain the majority of the clinical features of WS, but the underlying mechanisms driving the larger metabolic dysfunction remain elusive. Recent studies in animal models of WS and in WS patient cells and blood samples suggest the involvement of impaired mitophagy, NAD+ depletion, and accumulation of damaged mitochondria in metabolic dysfunction. This mini-review summarizes recent progress in the understanding of the molecular mechanisms of metabolic dysfunction in WS, with the involvement of DNA damage, mitochondrial dysfunction, mitophagy reduction, stem cell impairment, and senescence. Future studies on NAD+ and mitophagy may shed light on potential therapeutic strategies for the WS patients.
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Affiliation(s)
- Ruben Gudmundsrud
- Department of Clinical Molecular Biology, University of Oslo and Akershus University Hospital, Lørenskog, Norway
| | - Tarjei H Skjånes
- Department of Clinical Molecular Biology, University of Oslo and Akershus University Hospital, Lørenskog, Norway
| | - Brian C Gilmour
- The Norwegian Centre on Healthy Ageing (NO-Age), Oslo, Norway
| | - Domenica Caponio
- Department of Clinical Molecular Biology, University of Oslo and Akershus University Hospital, Lørenskog, Norway
| | - Sofie Lautrup
- Department of Clinical Molecular Biology, University of Oslo and Akershus University Hospital, Lørenskog, Norway
| | - Evandro F Fang
- Department of Clinical Molecular Biology, University of Oslo and Akershus University Hospital, Lørenskog, Norway.,The Norwegian Centre on Healthy Ageing (NO-Age), Oslo, Norway
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13
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RecQ helicases in DNA repair and cancer targets. Essays Biochem 2021; 64:819-830. [PMID: 33095241 PMCID: PMC7588665 DOI: 10.1042/ebc20200012] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 09/01/2020] [Accepted: 09/10/2020] [Indexed: 02/07/2023]
Abstract
Helicases are enzymes that use the energy derived from ATP hydrolysis to catalyze the unwinding of DNA or RNA. The RecQ family of helicases is conserved through evolution from prokaryotes to higher eukaryotes and plays important roles in various DNA repair pathways, contributing to the maintenance of genome integrity. Despite their roles as general tumor suppressors, there is now considerable interest in exploiting RecQ helicases as synthetic lethal targets for the development of new cancer therapeutics. In this review, we summarize the latest developments in the structural and mechanistic study of RecQ helicases and discuss their roles in various DNA repair pathways. Finally, we consider the potential to exploit RecQ helicases as therapeutic targets and review the recent progress towards the development of small molecules targeting RecQ helicases as cancer therapeutics.
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14
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Ababou M. Bloom syndrome and the underlying causes of genetic instability. Mol Genet Metab 2021; 133:35-48. [PMID: 33736941 DOI: 10.1016/j.ymgme.2021.03.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 02/01/2021] [Accepted: 03/06/2021] [Indexed: 11/27/2022]
Abstract
Autosomal hereditary recessive diseases characterized by genetic instability are often associated with cancer predisposition. Bloom syndrome (BS), a rare genetic disorder, with <300 cases reported worldwide, combines both. Indeed, patients with Bloom's syndrome are 150 to 300 times more likely to develop cancers than normal individuals. The wide spectrum of cancers developed by BS patients suggests that early initial events occur in BS cells which may also be involved in the initiation of carcinogenesis in the general population and these may be common to several cancers. BS is caused by mutations of both copies of the BLM gene, encoding the RecQ BLM helicase. This review discusses the different aspects of BS and the different cellular functions of BLM in genome surveillance and maintenance through its major roles during DNA replication, repair, and transcription. BLM's activities are essential for the stabilization of centromeric, telomeric and ribosomal DNA sequences, and the regulation of innate immunity. One of the key objectives of this work is to establish a link between BLM functions and the main clinical phenotypes observed in BS patients, as well as to shed new light on the correlation between the genetic instability and diseases such as immunodeficiency and cancer. The different potential implications of the BLM helicase in the tumorigenic process and the use of BLM as new potential target in the field of cancer treatment are also debated.
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Affiliation(s)
- Mouna Ababou
- Laboratory of Human Pathologies Biology, Department of Biology, Faculty of Sciences, University Mohammed V, Rabat, Morocco; Genomic Center of Human Pathologies, Faculty of medicine and Pharmacy, University Mohammed V, Rabat, Morocco.
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15
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Zhu XH, Sun BF, Luo M, Yu J, Zhang YD, Xu HQ, Luo H. Bloom helicase explicitly unwinds 3'-tailed G4DNA structure in prostate cancer cells. Int J Biol Macromol 2021; 180:578-589. [PMID: 33727188 DOI: 10.1016/j.ijbiomac.2021.03.060] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 01/22/2021] [Accepted: 03/11/2021] [Indexed: 10/21/2022]
Abstract
G-quadruplex DNA (G4DNA) structure, which widely exists in the chromosomal telomeric regions and oncogenic promoter regions, plays a pivotal role in extending telomeric DNA with the help of telomerase in human cells. Bloom (BLM) helicase, a crucial member of the family of genome surveillance proteins, plays an essential role in DNA metabolic and repair pathways, including DNA replication, repair, transcription, recombination during chromosome segregation, and assuring telomere stability. The unwinding of G4DNA requires the participation of DNA helicase, which is crucial for maintaining chromosomal stability in cancer cells. Using fluorescence polarization and the electrophoretic mobility shift assay (EMSA), this study aimed to investigate the DNA-binding and unwinding properties of BLM helicase, cloned and purified from prostate cancer cells, toward G4DNA. The results revealed that BLM helicase derived from prostate cancer cells could bind and unwind G4DNA. The molecular affinity of bond between G4DNA and the helicase was dependent on the single-stranded DNA (ssDNA) terminals in G4DNA; the helicase was effectively bound to the G4DNA when the helicase monomer sufficiently covered approximately 10 nucleotides at the 3' or 5' ssDNA tail of G4DNA. For the unwinding of G4DNA, there was an apparent requirement of a 3' ssDNA tail and ATP; a G4DNA with only a 3' ssDNA tail was identified to be the most suitable substrate to be unwound by BLM helicase and required 3' ssDNA tails of at least 10 nt in length for efficient unwinding. Besides, BLM helicase was loosely bound and partly unwound the blunt-ended G4DNA. Although further mechanistic studies are warranted, the experimental results presented in this study are beneficial to further our understanding of the functional implication of BLM helicase in prostate cancer cells.
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Affiliation(s)
- Xu-Hui Zhu
- State Key Laboratory of Functions And Applications of Medicinal Plants, Guizhou Medical University, Guiyang 550014, PR China; Beijing ChaoYang Hospital, Capital Medical University, Beijing 100016, PR China
| | - Bao-Fei Sun
- State Key Laboratory of Functions And Applications of Medicinal Plants, Guizhou Medical University, Guiyang 550014, PR China
| | - Mei Luo
- State Key Laboratory of Functions And Applications of Medicinal Plants, Guizhou Medical University, Guiyang 550014, PR China; The Key Laboratory of Chemistry for Natural Products of Guizhou Province and Chinese Academy of Science, Guiyang 550014, PR China
| | - Jia Yu
- State Key Laboratory of Functions And Applications of Medicinal Plants, Guizhou Medical University, Guiyang 550014, PR China; The Key Laboratory of Chemistry for Natural Products of Guizhou Province and Chinese Academy of Science, Guiyang 550014, PR China
| | | | - Hou-Qiang Xu
- Key Laboratory of Animal Genetics, Breeding and Reproduction in the Plateau Mountainous Region, Ministry of Education, College of Animal Science, Guizhou University, Guiyang 550025, PR China.
| | - Heng Luo
- State Key Laboratory of Functions And Applications of Medicinal Plants, Guizhou Medical University, Guiyang 550014, PR China; The Key Laboratory of Chemistry for Natural Products of Guizhou Province and Chinese Academy of Science, Guiyang 550014, PR China; Key Laboratory of Animal Genetics, Breeding and Reproduction in the Plateau Mountainous Region, Ministry of Education, College of Animal Science, Guizhou University, Guiyang 550025, PR China.
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16
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Lejault P, Mitteaux J, Sperti FR, Monchaud D. How to untie G-quadruplex knots and why? Cell Chem Biol 2021; 28:436-455. [PMID: 33596431 DOI: 10.1016/j.chembiol.2021.01.015] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Revised: 12/08/2020] [Accepted: 01/20/2021] [Indexed: 12/12/2022]
Abstract
For over two decades, the prime objective of the chemical biology community studying G-quadruplexes (G4s) has been to use chemicals to interact with and stabilize G4s in cells to obtain mechanistic interpretations. This strategy has been undoubtedly successful, as demonstrated by recent advances. However, these insights have also led to a fundamental rethinking of G4-targeting strategies: due to the prevalence of G4s in the human genome, transcriptome, and ncRNAome (collectively referred to as the G4ome), and their involvement in human diseases, should we continue developing G4-stabilizing ligands or should we invest in designing molecular tools to unfold G4s? Here, we first focus on how, when, and where G4s fold in cells; then, we describe the enzymatic systems that have evolved to counteract G4 folding and how they have been used as tools to manipulate G4s in cells; finally, we present strategies currently being implemented to devise new molecular G4 unwinding agents.
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Affiliation(s)
- Pauline Lejault
- Institut de Chimie Moléculaire de l'Université de Bourgogne, ICMUB CNRS UMR 6302, UBFC Dijon, France
| | - Jérémie Mitteaux
- Institut de Chimie Moléculaire de l'Université de Bourgogne, ICMUB CNRS UMR 6302, UBFC Dijon, France
| | - Francesco Rota Sperti
- Institut de Chimie Moléculaire de l'Université de Bourgogne, ICMUB CNRS UMR 6302, UBFC Dijon, France
| | - David Monchaud
- Institut de Chimie Moléculaire de l'Université de Bourgogne, ICMUB CNRS UMR 6302, UBFC Dijon, France.
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17
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Newman JA, Gavard AE, Lieb S, Ravichandran MC, Hauer K, Werni P, Geist L, Böttcher J, Engen JR, Rumpel K, Samwer M, Petronczki M, Gileadi O. Structure of the helicase core of Werner helicase, a key target in microsatellite instability cancers. Life Sci Alliance 2021; 4:e202000795. [PMID: 33199508 PMCID: PMC7671478 DOI: 10.26508/lsa.202000795] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 10/28/2020] [Accepted: 10/28/2020] [Indexed: 11/24/2022] Open
Abstract
Loss of WRN, a DNA repair helicase, was identified as a strong vulnerability of microsatellite instable (MSI) cancers, making WRN a promising drug target. We show that ATP binding and hydrolysis are required for genome integrity and viability of MSI cancer cells. We report a 2.2-Å crystal structure of the WRN helicase core (517-1,093), comprising the two helicase subdomains and winged helix domain but not the HRDC domain or nuclease domains. The structure highlights unusual features. First, an atypical mode of nucleotide binding that results in unusual relative positioning of the two helicase subdomains. Second, an additional β-hairpin in the second helicase subdomain and an unusual helical hairpin in the Zn2+ binding domain. Modelling of the WRN helicase in complex with DNA suggests roles for these features in the binding of alternative DNA structures. NMR analysis shows a weak interaction between the HRDC domain and the helicase core, indicating a possible biological role for this association. Together, this study will facilitate the structure-based development of inhibitors against WRN helicase.
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Affiliation(s)
- Joseph A Newman
- Structural Genomics Consortium, University of Oxford, Oxford, UK
| | | | - Simone Lieb
- Boehringer Ingelheim RCV GmbH & Co KG, Vienna, Austria
| | | | - Katja Hauer
- Boehringer Ingelheim RCV GmbH & Co KG, Vienna, Austria
| | - Patrick Werni
- Boehringer Ingelheim RCV GmbH & Co KG, Vienna, Austria
| | | | - Jark Böttcher
- Boehringer Ingelheim RCV GmbH & Co KG, Vienna, Austria
| | - John R Engen
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA, USA
| | - Klaus Rumpel
- Boehringer Ingelheim RCV GmbH & Co KG, Vienna, Austria
| | | | | | - Opher Gileadi
- Structural Genomics Consortium, University of Oxford, Oxford, UK
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18
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Dhar S, Datta A, Brosh RM. DNA helicases and their roles in cancer. DNA Repair (Amst) 2020; 96:102994. [PMID: 33137625 DOI: 10.1016/j.dnarep.2020.102994] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 09/28/2020] [Indexed: 12/15/2022]
Abstract
DNA helicases, known for their fundamentally important roles in genomic stability, are high profile players in cancer. Not only are there monogenic helicase disorders with a strong disposition to cancer, it is well appreciated that helicase variants are associated with specific cancers (e.g., breast cancer). Flipping the coin, DNA helicases are frequently overexpressed in cancerous tissues and reduction in helicase gene expression results in reduced proliferation and growth capacity, as well as DNA damage induction and apoptosis of cancer cells. The seminal roles of helicases in the DNA damage and replication stress responses, as well as DNA repair pathways, validate their vital importance in cancer biology and suggest their potential values as targets in anti-cancer therapy. In recent years, many laboratories have characterized the specialized roles of helicase to resolve transcription-replication conflicts, maintain telomeres, mediate cell cycle checkpoints, remodel stalled replication forks, and regulate transcription. In vivo models, particularly mice, have been used to interrogate helicase function and serve as a bridge for preclinical studies that may lead to novel therapeutic approaches. In this review, we will summarize our current knowledge of DNA helicases and their roles in cancer, emphasizing the latest developments.
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Affiliation(s)
- Srijita Dhar
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Arindam Datta
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Robert M Brosh
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA.
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19
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Structural Features of Nucleoprotein CST/Shelterin Complex Involved in the Telomere Maintenance and Its Association with Disease Mutations. Cells 2020; 9:cells9020359. [PMID: 32033110 PMCID: PMC7072152 DOI: 10.3390/cells9020359] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 01/23/2020] [Accepted: 01/24/2020] [Indexed: 12/29/2022] Open
Abstract
Telomere comprises the ends of eukaryotic linear chromosomes and is composed of G-rich (TTAGGG) tandem repeats which play an important role in maintaining genome stability, premature aging and onsets of many diseases. Majority of the telomere are replicated by conventional DNA replication, and only the last bit of the lagging strand is synthesized by telomerase (a reverse transcriptase). In addition to replication, telomere maintenance is principally carried out by two key complexes known as shelterin (TRF1, TRF2, TIN2, RAP1, POT1, and TPP1) and CST (CDC13/CTC1, STN1, and TEN1). Shelterin protects the telomere from DNA damage response (DDR) and regulates telomere length by telomerase; while, CST govern the extension of telomere by telomerase and C strand fill-in synthesis. We have investigated both structural and biochemical features of shelterin and CST complexes to get a clear understanding of their importance in the telomere maintenance. Further, we have analyzed ~115 clinically important mutations in both of the complexes. Association of such mutations with specific cellular fault unveils the importance of shelterin and CST complexes in the maintenance of genome stability. A possibility of targeting shelterin and CST by small molecule inhibitors is further investigated towards the therapeutic management of associated diseases. Overall, this review provides a possible direction to understand the mechanisms of telomere borne diseases, and their therapeutic intervention.
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20
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Lansdorp P, van Wietmarschen N. Helicases FANCJ, RTEL1 and BLM Act on Guanine Quadruplex DNA in Vivo. Genes (Basel) 2019; 10:genes10110870. [PMID: 31683575 PMCID: PMC6896191 DOI: 10.3390/genes10110870] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 10/29/2019] [Accepted: 10/29/2019] [Indexed: 02/03/2023] Open
Abstract
Guanine quadruplex (G4) structures are among the most stable secondary DNA structures that can form in vitro, and evidence for their existence in vivo has been steadily accumulating. Originally described mainly for their deleterious effects on genome stability, more recent research has focused on (potential) functions of G4 structures in telomere maintenance, gene expression, and other cellular processes. The combined research on G4 structures has revealed that properly regulating G4 DNA structures in cells is important to prevent genome instability and disruption of normal cell function. In this short review we provide some background and historical context of our work resulting in the identification of FANCJ, RTEL1 and BLM as helicases that act on G4 structures in vivo. Taken together these studies highlight important roles of different G4 DNA structures and specific G4 helicases at selected genomic locations and telomeres in regulating gene expression and maintaining genome stability.
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Affiliation(s)
- Peter Lansdorp
- Terry Fox Laboratory, British Columbia Cancer Agency, Vancouver, BC V5Z 1L3, Canada.
- Department of Medical Genetics, University of British Columbia, Vancouver, BC V6H 3N1, Canada.
- European Research Institute for the Biology of Ageing, University of Groningen, 9713 AV Groningen, The Netherlands.
| | - Niek van Wietmarschen
- European Research Institute for the Biology of Ageing, University of Groningen, 9713 AV Groningen, The Netherlands.
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD 20892, USA.
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21
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Billard P, Poncet DA. Replication Stress at Telomeric and Mitochondrial DNA: Common Origins and Consequences on Ageing. Int J Mol Sci 2019; 20:ijms20194959. [PMID: 31597307 PMCID: PMC6801922 DOI: 10.3390/ijms20194959] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 10/04/2019] [Accepted: 10/05/2019] [Indexed: 12/12/2022] Open
Abstract
Senescence is defined as a stress-induced durable cell cycle arrest. We herein revisit the origin of two of these stresses, namely mitochondrial metabolic compromise, associated with reactive oxygen species (ROS) production, and replicative senescence, activated by extreme telomere shortening. We discuss how replication stress-induced DNA damage of telomeric DNA (telDNA) and mitochondrial DNA (mtDNA) can be considered a common origin of senescence in vitro, with consequences on ageing in vivo. Unexpectedly, mtDNA and telDNA share common features indicative of a high degree of replicative stress, such as G-quadruplexes, D-loops, RNA:DNA heteroduplexes, epigenetic marks, or supercoiling. To avoid these stresses, both compartments use similar enzymatic strategies involving, for instance, endonucleases, topoisomerases, helicases, or primases. Surprisingly, many of these replication helpers are active at both telDNA and mtDNA (e.g., RNAse H1, FEN1, DNA2, RecQ helicases, Top2α, Top2β, TOP3A, DNMT1/3a/3b, SIRT1). In addition, specialized telomeric proteins, such as TERT (telomerase reverse transcriptase) and TERC (telomerase RNA component), or TIN2 (shelterin complex), shuttle from telomeres to mitochondria, and, by doing so, modulate mitochondrial metabolism and the production of ROS, in a feedback manner. Hence, mitochondria and telomeres use common weapons and cooperate to resist/prevent replication stresses, otherwise producing common consequences, namely senescence and ageing.
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Affiliation(s)
- Pauline Billard
- Univ Lyon, Université Claude Bernard Lyon 1, INSERM 1052, CNRS 5286, Centre Léon Bérard, Centre de recherche en cancérologie de Lyon, 69008 Lyon, France.
- Institut de Biopathologie moléculaire, Centre de Bio-Pathologie Est, Groupement hospitalier Est, Hospices Civils de Lyon, 69500 Bron, France.
| | - Delphine A Poncet
- Univ Lyon, Université Claude Bernard Lyon 1, INSERM 1052, CNRS 5286, Centre Léon Bérard, Centre de recherche en cancérologie de Lyon, 69008 Lyon, France.
- Institut de Biopathologie moléculaire, Centre de Bio-Pathologie Est, Groupement hospitalier Est, Hospices Civils de Lyon, 69500 Bron, France.
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22
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Barbero Barcenilla B, Shippen DE. Back to the future: The intimate and evolving connection between telomere-related factors and genotoxic stress. J Biol Chem 2019; 294:14803-14813. [PMID: 31434740 DOI: 10.1074/jbc.aw119.008145] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The conversion of circular genomes to linear chromosomes during molecular evolution required the invention of telomeres. This entailed the acquisition of factors necessary to fulfill two new requirements: the need to fully replicate terminal DNA sequences and the ability to distinguish chromosome ends from damaged DNA. Here we consider the multifaceted functions of factors recruited to perpetuate and stabilize telomeres. We discuss recent theories for how telomere factors evolved from existing cellular machineries and examine their engagement in nontelomeric functions such as DNA repair, replication, and transcriptional regulation. We highlight the remarkable versatility of protection of telomeres 1 (POT1) proteins that was fueled by gene duplication and divergence events that occurred independently across several eukaryotic lineages. Finally, we consider the relationship between oxidative stress and telomeres and the enigmatic role of telomere-associated proteins in mitochondria. These findings point to an evolving and intimate connection between telomeres and cellular physiology and the strong drive to maintain chromosome integrity.
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Affiliation(s)
- Borja Barbero Barcenilla
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843-2128
| | - Dorothy E Shippen
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843-2128
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23
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Lee M, Shin S, Uhm H, Hong H, Kirk J, Hyun K, Kulikowicz T, Kim J, Ahn B, Bohr VA, Hohng S. Multiple RPAs make WRN syndrome protein a superhelicase. Nucleic Acids Res 2019; 46:4689-4698. [PMID: 29668972 PMCID: PMC5961295 DOI: 10.1093/nar/gky272] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Accepted: 04/11/2018] [Indexed: 02/01/2023] Open
Abstract
RPA is known to stimulate the helicase activity of Werner syndrome protein (WRN), but the exact stimulation mechanism is not understood. We use single-molecule FRET and magnetic tweezers to investigate the helicase activity of WRN and its stimulation by RPA. We show that WRN alone is a weak helicase which repetitively unwind just a few tens of base pairs, but that binding of multiple RPAs to the enzyme converts WRN into a superhelicase that unidirectionally unwinds double-stranded DNA more than 1 kb. Our study provides a good case in which the activity and biological functions of the enzyme may be fundamentally altered by the binding of cofactors.
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Affiliation(s)
- Mina Lee
- Center for Nano-Bio Measurement, Korea Research Institute of Standards and Science, Daejeon, Republic of Korea
| | - Soochul Shin
- Department of Physics and Astronomy, Institute of Applied Physics, National Center of Creative Research Initiatives, Seoul National University, Seoul, Republic of Korea
| | - Heesoo Uhm
- Department of Physics and Astronomy, Institute of Applied Physics, National Center of Creative Research Initiatives, Seoul National University, Seoul, Republic of Korea
| | - Heesun Hong
- Department of Physics and Astronomy, Institute of Applied Physics, National Center of Creative Research Initiatives, Seoul National University, Seoul, Republic of Korea
| | - Jaewon Kirk
- Department of Physics and Astronomy, Institute of Applied Physics, National Center of Creative Research Initiatives, Seoul National University, Seoul, Republic of Korea
| | - Kwangbeom Hyun
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
| | - Tomasz Kulikowicz
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Jaehoon Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
| | - Byungchan Ahn
- Department of Life Sciences, University of Ulsan, Ulsan, Republic of Korea
| | - Vilhelm A Bohr
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Sungchul Hohng
- Department of Physics and Astronomy, Institute of Applied Physics, National Center of Creative Research Initiatives, Seoul National University, Seoul, Republic of Korea
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24
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Behnfeldt JH, Acharya S, Tangeman L, Gocha AS, Keirsey J, Groden J. A tri-serine cluster within the topoisomerase IIα-interaction domain of the BLM helicase is required for regulating chromosome breakage in human cells. Hum Mol Genet 2019; 27:1241-1251. [PMID: 29385443 DOI: 10.1093/hmg/ddy038] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 01/17/2018] [Indexed: 01/31/2023] Open
Abstract
The recQ-like helicase BLM interacts directly with topoisomerase IIα to regulate chromosome breakage in human cells. We demonstrate that a phosphosite tri-serine cluster (S577/S579/S580) within the BLM topoisomerase IIα-interaction region is required for this function. Enzymatic activities of BLM and topoisomerase IIα are reciprocally stimulated in vitro by ten-fold for topoisomerase IIα decatenation/relaxation activity and three-fold for BLM unwinding of forked DNA duplex substrates. A BLM transgene encoding alanine substitutions of the tri-serine cluster in BLM-/- transfected cells increases micronuclei, DNA double strand breaks and anaphase ultra-fine bridges (UFBs), and decreases cellular co-localization of BLM with topoisomerase IIα. In vitro, these substitutions significantly reduce the topoisomerase IIα-mediated stimulation of BLM unwinding of forked DNA duplexes. Substitution of the tri-serine cluster with aspartic acids to mimic serine phosphorylation reverses these effects in vitro and in vivo. Our findings implicate the modification of this BLM tri-serine cluster in regulating chromosomal stability.
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Affiliation(s)
- Julia Harris Behnfeldt
- Department of Cancer Biology and Genetics, College of Medicine, The Ohio State University, Columbus, OH 43210, USA
| | - Samir Acharya
- Department of Cancer Biology and Genetics, College of Medicine, The Ohio State University, Columbus, OH 43210, USA
| | - Larissa Tangeman
- Department of Cancer Biology and Genetics, College of Medicine, The Ohio State University, Columbus, OH 43210, USA
| | - April Sandy Gocha
- Department of Cancer Biology and Genetics, College of Medicine, The Ohio State University, Columbus, OH 43210, USA
| | - Jeremy Keirsey
- Department of Cancer Biology and Genetics, College of Medicine, The Ohio State University, Columbus, OH 43210, USA
| | - Joanna Groden
- Department of Cancer Biology and Genetics, College of Medicine, The Ohio State University, Columbus, OH 43210, USA
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25
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Lerner LK, Sale JE. Replication of G Quadruplex DNA. Genes (Basel) 2019; 10:genes10020095. [PMID: 30700033 PMCID: PMC6409989 DOI: 10.3390/genes10020095] [Citation(s) in RCA: 95] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 01/21/2019] [Accepted: 01/23/2019] [Indexed: 01/03/2023] Open
Abstract
A cursory look at any textbook image of DNA replication might suggest that the complex machine that is the replisome runs smoothly along the chromosomal DNA. However, many DNA sequences can adopt non-B form secondary structures and these have the potential to impede progression of the replisome. A picture is emerging in which the maintenance of processive DNA replication requires the action of a significant number of additional proteins beyond the core replisome to resolve secondary structures in the DNA template. By ensuring that DNA synthesis remains closely coupled to DNA unwinding by the replicative helicase, these factors prevent impediments to the replisome from causing genetic and epigenetic instability. This review considers the circumstances in which DNA forms secondary structures, the potential responses of the eukaryotic replisome to these impediments in the light of recent advances in our understanding of its structure and operation and the mechanisms cells deploy to remove secondary structure from the DNA. To illustrate the principles involved, we focus on one of the best understood DNA secondary structures, G quadruplexes (G4s), and on the helicases that promote their resolution.
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Affiliation(s)
- Leticia Koch Lerner
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK.
| | - Julian E Sale
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK.
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26
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Ahmed W, Lingner J. PRDX1 and MTH1 cooperate to prevent ROS-mediated inhibition of telomerase. Genes Dev 2018; 32:658-669. [PMID: 29773556 PMCID: PMC6004070 DOI: 10.1101/gad.313460.118] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Accepted: 04/23/2018] [Indexed: 11/29/2022]
Abstract
In this study, Ahmed et al. demonstrate that oxidative damage of telomeres inhibits telomerase activity at chromosome ends in cancer cells. Deletion of two antioxidant enzymes—PRDX1 and MTH1, needed for protecting telomeres from oxidative damage—results in loss of telomeric DNA in an oxygen concentration-dependent manner due to inhibition of telomerase, thus providing new insights into the role of antioxidant systems that are required to protect telomeres from oxidation. Telomerase counteracts telomere shortening and cellular senescence in germ, stem, and cancer cells by adding repetitive DNA sequences to the ends of chromosomes. Telomeres are susceptible to damage by reactive oxygen species (ROS), but the consequences of oxidation of telomeres on telomere length and the mechanisms that protect from ROS-mediated telomere damage are not well understood. In particular, 8-oxoguanine nucleotides at 3′ ends of telomeric substrates inhibit telomerase in vitro, whereas, at internal positions, they suppress G-quadruplex formation and were therefore proposed to promote telomerase activity. Here, we disrupt the peroxiredoxin 1 (PRDX1) and 7,8-dihydro-8-oxoguanine triphosphatase (MTH1) genes in cancer cells and demonstrate that PRDX1 and MTH1 cooperate to prevent accumulation of oxidized guanine in the genome. Concomitant disruption of PRDX1 and MTH1 leads to ROS concentration-dependent continuous shortening of telomeres, which is due to efficient inhibition of telomere extension by telomerase. Our results identify antioxidant systems that are required to protect telomeres from oxidation and are necessary to allow telomere maintenance by telomerase conferring immortality to cancer cells.
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Affiliation(s)
- Wareed Ahmed
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Joachim Lingner
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
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27
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Yu EY, Hsu M, Holloman WK, Lue NF. Contributions of recombination and repair proteins to telomere maintenance in telomerase-positive and negative Ustilago maydis. Mol Microbiol 2017; 107:81-93. [PMID: 29052918 DOI: 10.1111/mmi.13866] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Revised: 10/13/2017] [Accepted: 10/14/2017] [Indexed: 11/26/2022]
Abstract
Homologous recombination and repair factors are known to promote both telomere replication and recombination-based telomere extension. Herein, we address the diverse contributions of several recombination/repair proteins to telomere maintenance in Ustilago maydis, a fungus that bears strong resemblance to mammals with respect to telomere regulation and recombination mechanisms. In telomerase-positive U. maydis, deletion of rad51 and blm separately caused shortened but stably maintained telomeres, whereas deletion of both engendered similar telomere loss, suggesting that the repair proteins help to resolve similar problems in telomere replication. In telomerase-negative cells, the loss of Rad51 or Brh2 caused accelerated senescence and failure to generate survivors on semi-solid medium. However, slow growing survivors can be isolated through continuous liquid culturing, and these survivors exhibit type II-like as well as ALT-like telomere features. In contrast, the trt1Δ blmΔ double mutant gives rise to survivors as readily as the trt1Δ single mutant, and like the single mutant survivors, exhibit almost exclusively type I-like telomere features. In addition, we observed direct physical interactions between Blm and two telomere-binding proteins, which may thus recruit or regulate Blm at telomeres. Our findings provide the basis for further analyzing the interplays between telomerase, telomere replication, and telomere recombination.
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Affiliation(s)
- Eun Young Yu
- Department of Microbiology & Immunology, W. R. Hearst Microbiology Research Center Weill Medical College of Cornell University, New York, NY, USA
| | - Min Hsu
- Department of Microbiology & Immunology, W. R. Hearst Microbiology Research Center Weill Medical College of Cornell University, New York, NY, USA
| | - William K Holloman
- Department of Microbiology & Immunology, W. R. Hearst Microbiology Research Center Weill Medical College of Cornell University, New York, NY, USA
| | - Neal F Lue
- Department of Microbiology & Immunology, W. R. Hearst Microbiology Research Center Weill Medical College of Cornell University, New York, NY, USA.,Sandra and Edward Meyer Cancer Center, Weill Cornell Medical College, New York, NY, USA
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Abstract
Aging, the universal phenomenon, affects human health and is the primary risk factor for major disease pathologies. Progeroid diseases, which mimic aging at an accelerated rate, have provided cues in understanding the hallmarks of aging. Mutations in DNA repair genes as well as in telomerase subunits are known to cause progeroid syndromes. Werner syndrome (WS), which is characterized by accelerated aging, is an autosomal-recessive genetic disorder. Hallmarks that define the aging process include genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, deregulation of nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, and altered intercellular communication. WS recapitulates these hallmarks of aging and shows increased incidence and early onset of specific cancers. Genome integrity and stability ensure the normal functioning of the cell and are mainly guarded by the DNA repair machinery and telomeres. WRN, being a RecQ helicase, protects genome stability by regulating DNA repair pathways and telomeres. Recent advances in WS research have elucidated WRN’s role in DNA repair pathway choice regulation, telomere maintenance, resolution of complex DNA structures, epigenetic regulation, and stem cell maintenance.
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Affiliation(s)
- Raghavendra A Shamanna
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Deborah L Croteau
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Jong-Hyuk Lee
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Vilhelm A Bohr
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
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29
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DNA Replication Origins and Fork Progression at Mammalian Telomeres. Genes (Basel) 2017; 8:genes8040112. [PMID: 28350373 PMCID: PMC5406859 DOI: 10.3390/genes8040112] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 03/23/2017] [Accepted: 03/24/2017] [Indexed: 12/20/2022] Open
Abstract
Telomeres are essential chromosomal regions that prevent critical shortening of linear chromosomes and genomic instability in eukaryotic cells. The bulk of telomeric DNA is replicated by semi-conservative DNA replication in the same way as the rest of the genome. However, recent findings revealed that replication of telomeric repeats is a potential cause of chromosomal instability, because DNA replication through telomeres is challenged by the repetitive telomeric sequences and specific structures that hamper the replication fork. In this review, we summarize current understanding of the mechanisms by which telomeres are faithfully and safely replicated in mammalian cells. Various telomere-associated proteins ensure efficient telomere replication at different steps, such as licensing of replication origins, passage of replication forks, proper fork restart after replication stress, and dissolution of post-replicative structures. In particular, shelterin proteins have central roles in the control of telomere replication. Through physical interactions, accessory proteins are recruited to maintain telomere integrity during DNA replication. Dormant replication origins and/or homology-directed repair may rescue inappropriate fork stalling or collapse that can cause defects in telomere structure and functions.
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30
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Berardinelli F, Coluzzi E, Sgura A, Antoccia A. Targeting telomerase and telomeres to enhance ionizing radiation effects in in vitro and in vivo cancer models. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2017; 773:204-219. [PMID: 28927529 DOI: 10.1016/j.mrrev.2017.02.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Revised: 02/13/2017] [Accepted: 02/14/2017] [Indexed: 01/05/2023]
Abstract
One of the hallmarks of cancer consists in the ability of tumor cells to divide indefinitely, and to maintain stable telomere lengths throughout the activation of specific telomere maintenance mechanisms (TMM). Therefore in the last fifteen years, researchers proposed to target telomerase or telomeric structure in order to block limitless replicative potential of cancer cells providing a fascinating strategy for a broad-spectrum cancer therapy. In the present review, we report in vitro and in vivo evidence regarding the use of chemical agents targeting both telomerase or telomere structure and showing promising antitumor effects when used in combination with ionizing radiation (IR). RNA interference, antisense oligonucleotides (e.g., GRN163L), non-nucleoside inhibitors (e.g., BIBR1532) and nucleoside analogs (e.g., AZT) represent some of the most potent strategies to inhibit telomerase activity used in combination with IR. Furthermore, radiosensitizing effects were demonstrated also for agents acting directly on the telomeric structure such as G4-ligands (e.g., RHPS4 and Telomestatin) or telomeric-oligos (T-oligos). To date, some of these compounds are under clinical evaluation (e.g., GRN163L and KML001). Advantages of Telomere/Telomerase Targeting Compounds (T/TTCs) coupled with radiotherapy may be relevant in the treatment of radioresistant tumors and in the development of new optimized treatment plans with reduced dose adsorbed by patients and consequent attenuation of short- end long-term side effects. Pros and cons of possible future applications in cancer therapy based on the combination of T/TCCs and radiation treatment are discussed.
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Affiliation(s)
- F Berardinelli
- Dipartimento di Scienze, Università Roma Tre, Rome Italy; Istituto Nazionale di Fisica Nucleare, INFN, Sezione di Roma Tre, Rome, Italy.
| | - E Coluzzi
- Dipartimento di Scienze, Università Roma Tre, Rome Italy
| | - A Sgura
- Dipartimento di Scienze, Università Roma Tre, Rome Italy; Istituto Nazionale di Fisica Nucleare, INFN, Sezione di Roma Tre, Rome, Italy
| | - A Antoccia
- Dipartimento di Scienze, Università Roma Tre, Rome Italy; Istituto Nazionale di Fisica Nucleare, INFN, Sezione di Roma Tre, Rome, Italy
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31
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Maestroni L, Matmati S, Coulon S. Solving the Telomere Replication Problem. Genes (Basel) 2017; 8:genes8020055. [PMID: 28146113 PMCID: PMC5333044 DOI: 10.3390/genes8020055] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 01/23/2017] [Indexed: 12/12/2022] Open
Abstract
Telomeres are complex nucleoprotein structures that protect the extremities of linear chromosomes. Telomere replication is a major challenge because many obstacles to the progression of the replication fork are concentrated at the ends of the chromosomes. This is known as the telomere replication problem. In this article, different and new aspects of telomere replication, that can threaten the integrity of telomeres, will be reviewed. In particular, we will focus on the functions of shelterin and the replisome for the preservation of telomere integrity.
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Affiliation(s)
- Laetitia Maestroni
- Aix Marseille Univ, CNRS, INSERM, Institut Paoli-Calmettes, CRCM, Equipe labélisée Ligue Contre le Cancer, 13273 Marseille, France.
| | - Samah Matmati
- Aix Marseille Univ, CNRS, INSERM, Institut Paoli-Calmettes, CRCM, Equipe labélisée Ligue Contre le Cancer, 13273 Marseille, France.
| | - Stéphane Coulon
- Aix Marseille Univ, CNRS, INSERM, Institut Paoli-Calmettes, CRCM, Equipe labélisée Ligue Contre le Cancer, 13273 Marseille, France.
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32
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Bloom's syndrome: Why not premature aging?: A comparison of the BLM and WRN helicases. Ageing Res Rev 2017; 33:36-51. [PMID: 27238185 DOI: 10.1016/j.arr.2016.05.010] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Revised: 05/17/2016] [Accepted: 05/19/2016] [Indexed: 01/19/2023]
Abstract
Genomic instability is a hallmark of cancer and aging. Premature aging (progeroid) syndromes are often caused by mutations in genes whose function is to ensure genomic integrity. The RecQ family of DNA helicases is highly conserved and plays crucial roles as genome caretakers. In humans, mutations in three RecQ genes - BLM, WRN, and RECQL4 - give rise to Bloom's syndrome (BS), Werner syndrome (WS), and Rothmund-Thomson syndrome (RTS), respectively. WS is a prototypic premature aging disorder; however, the clinical features present in BS and RTS do not indicate accelerated aging. The BLM helicase has pivotal functions at the crossroads of DNA replication, recombination, and repair. BS cells exhibit a characteristic form of genomic instability that includes excessive homologous recombination. The excessive homologous recombination drives the development in BS of the many types of cancers that affect persons in the normal population. Replication delay and slower cell turnover rates have been proposed to explain many features of BS, such as short stature. More recently, aberrant transcriptional regulation of growth and survival genes has been proposed as a hypothesis to explain features of BS.
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33
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Distinct functions of human RecQ helicases during DNA replication. Biophys Chem 2016; 225:20-26. [PMID: 27876204 DOI: 10.1016/j.bpc.2016.11.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Revised: 11/13/2016] [Accepted: 11/13/2016] [Indexed: 12/31/2022]
Abstract
DNA replication is the most vulnerable process of DNA metabolism in proliferating cells and therefore it is tightly controlled and coordinated with processes that maintain genomic stability. Human RecQ helicases are among the most important factors involved in the maintenance of replication fork integrity, especially under conditions of replication stress. RecQ helicases promote recovery of replication forks being stalled due to different replication roadblocks of either exogenous or endogenous source. They prevent generation of aberrant replication fork structures and replication fork collapse, and are involved in proper checkpoint signaling. The essential role of human RecQ helicases in the genome maintenance during DNA replication is underlined by association of defects in their function with cancer predisposition.
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34
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Lue NF, Yu EY. Telomere recombination pathways: tales of several unhappy marriages. Curr Genet 2016; 63:401-409. [PMID: 27666406 DOI: 10.1007/s00294-016-0653-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2016] [Revised: 09/19/2016] [Accepted: 09/21/2016] [Indexed: 01/29/2023]
Abstract
All happy families are alike; each unhappy family is unhappy in its own way.-Leo Tolstoy, Anna Karenina.
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Affiliation(s)
- Neal F Lue
- Department of Microbiology and Immunology, W. R. Hearst Microbiology Research Center, Weill Cornell Medicine, New York, NY, USA. .,Meyer Cancer Center, Weill Cornell Medicine, New York, NY, USA.
| | - Eun Young Yu
- Department of Microbiology and Immunology, W. R. Hearst Microbiology Research Center, Weill Cornell Medicine, New York, NY, USA
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35
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Bermúdez-López M, Aragon L. Smc5/6 complex regulates Sgs1 recombination functions. Curr Genet 2016; 63:381-388. [PMID: 27664093 PMCID: PMC5422486 DOI: 10.1007/s00294-016-0648-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Revised: 09/02/2016] [Accepted: 09/03/2016] [Indexed: 11/07/2022]
Abstract
The family of RecQ helicases is evolutionary conserved from bacteria to humans and play key roles in genome stability. The budding yeast RecQ helicase Sgs1 has been implicated in several key processes during the repair of DNA damage by homologous recombination as part of the STR complex (Sgs1-Top3-Rmi1). Limited information on how is Sgs1 recruited and regulated at sites of damage is available. Recently, we and others have uncover a direct link between the Smc5/6 complex and Sgs1. Most roles of Sgs1 during recombination, including DNA end resection, Holiday junction dissolution, and crossover suppression, are regulated through Mms21-dependent SUMOylation. Smc5/6 first acts as a recruiting platform for STR and then SUMOylates STR components to regulate their function. Importantly, the assembly of STR is totally independent of Smc5/6. Here, we provide a brief overview of STR regulation by Smc5/6.
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Affiliation(s)
| | - Luis Aragon
- Cell Cycle Group, MRC Clinical Sciences Centre, Imperial College, London, W12 0NN, UK.
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36
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Drosopoulos WC, Kosiyatrakul ST, Schildkraut CL. BLM helicase facilitates telomere replication during leading strand synthesis of telomeres. J Cell Biol 2016. [PMID: 26195664 PMCID: PMC4508891 DOI: 10.1083/jcb.201410061] [Citation(s) in RCA: 110] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
BLM helicase facilitates telomere replication by resolving G-quadruplex structures that can form in the G-rich repeats during leading strand synthesis. Based on its in vitro unwinding activity on G-quadruplex (G4) DNA, the Bloom syndrome–associated helicase BLM is proposed to participate in telomere replication by aiding fork progression through G-rich telomeric DNA. Single molecule analysis of replicated DNA (SMARD) was used to determine the contribution of BLM helicase to telomere replication. In BLM-deficient cells, replication forks initiating from origins within the telomere, which copy the G-rich strand by leading strand synthesis, moved slower through the telomere compared with the adjacent subtelomere. Fork progression through the telomere was further slowed in the presence of a G4 stabilizer. Using a G4-specific antibody, we found that deficiency of BLM, or another G4-unwinding helicase, the Werner syndrome-associated helicase WRN, resulted in increased G4 structures in cells. Importantly, deficiency of either helicase led to greater increases in G4 DNA detected in the telomere compared with G4 seen genome-wide. Collectively, our findings are consistent with BLM helicase facilitating telomere replication by resolving G4 structures formed during copying of the G-rich strand by leading strand synthesis.
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Affiliation(s)
| | | | - Carl L Schildkraut
- Department of Cell Biology, Albert Einstein College of Medicine, New York, NY 10461
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37
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Tang W, Robles AI, Beyer RP, Gray LT, Nguyen GH, Oshima J, Maizels N, Harris CC, Monnat RJ. The Werner syndrome RECQ helicase targets G4 DNA in human cells to modulate transcription. Hum Mol Genet 2016; 25:2060-2069. [PMID: 26984941 DOI: 10.1093/hmg/ddw079] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Accepted: 03/07/2016] [Indexed: 11/12/2022] Open
Abstract
The Werner syndrome (WS) is a prototypic adult Mendelian progeroid syndrome in which signs of premature aging are associated with genomic instability and an elevated risk of cancer. The WRN RECQ helicase protein binds and unwinds G-quadruplex (G4) DNA substrates in vitro, and we identified significant enrichment in G4 sequence motifs at the transcription start site and 5' ends of first introns (false discovery rate < 0.001) of genes down-regulated in WS patient fibroblasts. This finding provides strong evidence that WRN binds G4 DNA structures at many chromosomal sites to modulate gene expression. WRN appears to bind a distinct subpopulation of G4 motifs in human cells, when compared with the related Bloom syndrome RECQ helicase protein. Functional annotation of the genes and miRNAs altered in WS provided new insight into WS disease pathogenesis. WS patient fibroblasts displayed altered expression of multiple, mechanistically distinct, senescence-associated gene expression programs, with altered expression of disease-associated miRNAs, and dysregulation of canonical pathways that regulate cell signaling, genome stability and tumorigenesis. WS fibroblasts also displayed a highly statistically significant and distinct gene expression signature, with coordinate overexpression of nearly all of the cytoplasmic tRNA synthetases and associated ARS-interacting multifunctional protein genes. The 'non-canonical' functions of many of these upregulated tRNA charging proteins may together promote WS disease pathogenesis. Our results identify the human WRN RECQ protein as a G4 helicase that modulates gene expression in G4-dependent fashion at many chromosomal sites and provide several new and unexpected mechanistic insights into WS disease pathogenesis.
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Affiliation(s)
| | - Ana I Robles
- Laboratory of Human Carcinogenesis, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA and
| | | | | | - Giang H Nguyen
- Laboratory of Human Carcinogenesis, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA and
| | - Junko Oshima
- Department of Pathology, Department of Medicine, Chiba University, Chiba, Japan
| | - Nancy Maizels
- Department of Pathology, Department of Immunology, Department of Biochemistry
| | - Curtis C Harris
- Laboratory of Human Carcinogenesis, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA and
| | - Raymond J Monnat
- Department of Pathology, Department of Genome Sciences, University of Washington, Seattle, WA, USA,
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Viziteu E, Kassambara A, Pasero P, Klein B, Moreaux J. RECQ helicases are deregulated in hematological malignancies in association with a prognostic value. Biomark Res 2016; 4:3. [PMID: 26877874 PMCID: PMC4752763 DOI: 10.1186/s40364-016-0057-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 02/08/2016] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND RECQ helicase family members act as guardians of the genome to assure proper DNA metabolism in response to genotoxic stress. Hematological malignancies are characterized by genomic instability that is possibly related to underlying defects in DNA repair of genomic stability maintenance. METHODS We have investigated the expression of RECQ helicases in different hematological malignancies and in their normal counterparts using publicly available gene expression data. Furthermore, we explored whether RECQ helicases expression could be associated with tumor progression and prognosis. RESULTS Expression of at least one RECQ helicase family member was found significantly deregulated in all hematological malignancies investigated when compared to their normal counterparts. In addition, RECQ helicase expression was associated with a prognostic value in acute myeloid leukemia, chronic lymphocytic leukemia, lymphoma and multiple myeloma. CONCLUSION RECQ helicase expression is deregulated in hematological malignancies compared to their normal counterparts in association with a prognostic value. Deregulation of RECQ helicases appears to play a role in tumorigenesis and represent potent therapeutic targets for synthetic lethal approaches in hematological malignancies.
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Affiliation(s)
- Elena Viziteu
- />Institute of Human Genetics, CNRS-UPR1142, Montpellier, F-34396 France
| | - Alboukadel Kassambara
- />Laboratory for Monitoring Innovative Therapies, Department of Biological Hematology, Hôpital Saint-Eloi - CHRU de Montpellier, 80, av. Augustin Fliche, 34295 Montpellier, Cedex 5 France
- />Institute of Human Genetics, CNRS-UPR1142, Montpellier, F-34396 France
| | - Philippe Pasero
- />Institute of Human Genetics, CNRS-UPR1142, Montpellier, F-34396 France
| | - Bernard Klein
- />Laboratory for Monitoring Innovative Therapies, Department of Biological Hematology, Hôpital Saint-Eloi - CHRU de Montpellier, 80, av. Augustin Fliche, 34295 Montpellier, Cedex 5 France
- />Institute of Human Genetics, CNRS-UPR1142, Montpellier, F-34396 France
- />University of Montpellier 1, UFR de Médecine, Montpellier, France
| | - Jerome Moreaux
- />Laboratory for Monitoring Innovative Therapies, Department of Biological Hematology, Hôpital Saint-Eloi - CHRU de Montpellier, 80, av. Augustin Fliche, 34295 Montpellier, Cedex 5 France
- />Institute of Human Genetics, CNRS-UPR1142, Montpellier, F-34396 France
- />University of Montpellier 1, UFR de Médecine, Montpellier, France
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Elevated levels of TRF2 induce telomeric ultrafine anaphase bridges and rapid telomere deletions. Nat Commun 2015; 6:10132. [PMID: 26640040 PMCID: PMC4686832 DOI: 10.1038/ncomms10132] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 11/05/2015] [Indexed: 01/23/2023] Open
Abstract
The shelterin protein TRF2 is essential for chromosome-end protection. Depletion of TRF2 causes chromosome end-to-end fusions, initiating genomic instability that can be cancer promoting. Paradoxically, significant increased levels of TRF2 are observed in a subset of human cancers. Experimental overexpression of TRF2 has also been shown to induce telomere shortening, through an unknown mechanism. Here we report that TRF2 overexpression results in replication stalling in duplex telomeric repeat tracts and the subsequent formation of telomeric ultrafine anaphase bridges (UFBs), ultimately leading to stochastic loss of telomeric sequences. These TRF2 overexpression-induced telomere deletions generate chromosome fusions resembling those detected in human cancers and in mammalian cells containing critically shortened telomeres. Therefore, our findings have uncovered a second pathway by which altered TRF2 protein levels can induce end-to-end fusions. The observations also provide mechanistic insight into the molecular basis of genomic instability in tumour cells containing significantly increased TRF2 levels.
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40
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Smestad JA, Maher LJ. Relationships between putative G-quadruplex-forming sequences, RecQ helicases, and transcription. BMC MEDICAL GENETICS 2015; 16:91. [PMID: 26449372 PMCID: PMC4599794 DOI: 10.1186/s12881-015-0236-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 09/23/2015] [Indexed: 01/11/2023]
Abstract
Background Putative G-quadruplex-forming sequences (PQS) have long been implicated in regulation of transcription, though the actual mechanisms are not well understood. One proposed mechanism involves the activity of PQS-specific helicases belonging to the RecQ helicase family. However, patterns of PQS that correlate with transcriptional sensitivity to RecQ helicases are not well studied, and no adequate transcriptional model exists to account for PQS effects. Methods To better understand PQS transcriptional effects, we analyze PQS motifs in genes differentially-transcribed in Bloom Syndrome (BS) and Werner Syndrome (WS), two disorders resulting in loss of PQS-interacting RecQ helicases. We also correlate PQS genome-wide with transcription in multiple human cells lines while controlling for epigenetic status. Finally, we perform neural network clustering of PQS motifs to assess whether certain motifs are over-represented in genes sensitive to RecQ helicase loss. Results By analyzing PQS motifs in promoters of genes differentially-transcribed in BS and WS, we demonstrate that abundance of promoter PQS is generally higher in down-regulated genes and lower in up-regulated genes, and show that these effects are position-dependent. To interpret these correlations we determined genome-wide PQS correlations with transcription while controlling for epigenetic status. Our results identify multiple discrete transcription start site-proximal positions where PQS are correlated with either increased or decreased transcription. Finally, we report neural network clustering analysis of PQS motifs demonstrating that genes differentially-expressed in BS and WS are significantly biased in PQS motif composition. Conclusions Our findings unveil unappreciated detail in the relationship between PQS, RecQ helicases, and transcription. We show that promoter PQS are generally correlated with reduced gene expression, and that this effect is relieved by RecQ helicases. We also show that PQS at certain positions on the downstream sense strand are correlated with increased transcription. We therefore propose a new transcriptional model in which promoter PQS have at least two distinct types of transcriptional regulatory effects. Electronic supplementary material The online version of this article (doi:10.1186/s12881-015-0236-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- John A Smestad
- Mayo Clinic Medical Scientist Training Program, Mayo Clinic College of Medicine, 200 First St. SW, Rochester, MN, 55905, USA.
| | - L James Maher
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, 200 First St. SW, Rochester, MN, 55905, USA.
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41
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The DNA structure and sequence preferences of WRN underlie its function in telomeric recombination events. Nat Commun 2015; 6:8331. [PMID: 26420422 PMCID: PMC4589872 DOI: 10.1038/ncomms9331] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 08/11/2015] [Indexed: 12/27/2022] Open
Abstract
Telomeric abnormalities caused by loss of function of the RecQ helicase WRN are linked to the multiple premature ageing phenotypes that characterize Werner syndrome. Here we examine WRN's role in telomeric maintenance, by comparing its action on a variety of DNA structures without or with telomeric sequences. Our results show that WRN clearly prefers to act on strand invasion intermediates in a manner that favours strand invasion and exchange. Moreover, WRN unwinding of these recombination structures is further enhanced when the invading strand contains at least three G-rich single-stranded telomeric repeats. These selectivities are most pronounced at NaCl concentrations within the reported intranuclear monovalent cation concentration range, and are partly conferred by WRN's C-terminal region. Importantly, WRN's specificity for the G-rich telomeric sequence within this precise structural context is particularly relevant to telomere metabolism and strongly suggests a physiological role in telomeric recombination processes, including T-loop dynamics.
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Rhodes D, Lipps HJ. G-quadruplexes and their regulatory roles in biology. Nucleic Acids Res 2015; 43:8627-37. [PMID: 26350216 PMCID: PMC4605312 DOI: 10.1093/nar/gkv862] [Citation(s) in RCA: 1010] [Impact Index Per Article: 112.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 08/17/2015] [Indexed: 01/10/2023] Open
Abstract
‘If G-quadruplexes form so readily in vitro, Nature will have found a way of using them in vivo’ (Statement by Aaron Klug over 30 years ago). During the last decade, four-stranded helical structures called G-quadruplex (or G4) have emerged from being a structural curiosity observed in vitro, to being recognized as a possible nucleic acid based mechanism for regulating multiple biological processes in vivo. The sequencing of many genomes has revealed that they are rich in sequence motifs that have the potential to form G-quadruplexes and that their location is non-random, correlating with functionally important genomic regions. In this short review, we summarize recent evidence for the in vivo presence and function of DNA and RNA G-quadruplexes in various cellular pathways including DNA replication, gene expression and telomere maintenance. We also highlight remaining open questions that will have to be addressed in the future.
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Affiliation(s)
- Daniela Rhodes
- School of Biological Sciences, Nanyang Technological University, Proteos, 61 Biopolis Drive, 138673, Singapore Lee Kong Chian School of Medicine, Nanyang Technological University, Proteos, 61 Biopolis Drive, 138673, Singapore Nanyang Institute of Structural Biology, Nanyang Technological University, Proteos, 61 Biopolis Drive, 138673, Singapore
| | - Hans J Lipps
- Centre for biomedical education and research (ZBAF), Institute of Cell Biology, University Witten/Herdecke, Stockumer Str. 10, 58448, Witten, Germany
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RecQ helicases and PARP1 team up in maintaining genome integrity. Ageing Res Rev 2015; 23:12-28. [PMID: 25555679 DOI: 10.1016/j.arr.2014.12.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2014] [Revised: 12/18/2014] [Accepted: 12/22/2014] [Indexed: 01/04/2023]
Abstract
Genome instability represents a primary hallmark of aging and cancer. RecQL helicases (i.e., RECQL1, WRN, BLM, RECQL4, RECQL5) as well as poly(ADP-ribose) polymerases (PARPs, in particular PARP1) represent two central quality control systems to preserve genome integrity in mammalian cells. Consistently, both enzymatic families have been linked to mechanisms of aging and carcinogenesis in mice and humans. This is in accordance with clinical and epidemiological findings demonstrating that defects in three RecQL helicases, i.e., WRN, BLM, RECQL4, are related to human progeroid and cancer predisposition syndromes, i.e., Werner, Bloom, and Rothmund Thomson syndrome, respectively. Moreover, PARP1 hypomorphy is associated with a higher risk for certain types of cancer. On a molecular level, RecQL helicases and PARP1 are involved in the control of DNA repair, telomere maintenance, and replicative stress. Notably, over the last decade, it became apparent that all five RecQL helicases physically or functionally interact with PARP1 and/or its enzymatic product poly(ADP-ribose) (PAR). Furthermore, a profound body of evidence revealed that the cooperative function of RECQLs and PARP1 represents an important factor for maintaining genome integrity. In this review, we summarize the status quo of this molecular cooperation and discuss open questions that provide a basis for future studies to dissect the cooperative functions of RecQL helicases and PARP1 in aging and carcinogenesis.
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Lei H, Zhou FX, Xu H, Peng XH, Zhang ZG, Wang WB, Yu HJ, Xie CH, Zhou YF. Expression of various protection of telomeres 1 variants is associated with telomere length and radiosensitivity in colon and gastric adenocarcinoma cells in vitro. Biomed Rep 2015; 3:420-424. [PMID: 26137248 DOI: 10.3892/br.2015.444] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Accepted: 03/06/2015] [Indexed: 12/13/2022] Open
Abstract
Protection of telomeres 1 (POT1) is a telomere-binding protein, which binds to the single-stranded DNA extensions of telomeres and regulates telomere length. Different POT1 mRNA variants were examined and compared with telomere length and radiosensitivity in colon and gastric adenocarcinoma cells. POT1 production and telomere lengths were assessed using 10 human cancer cell lines by quantitative polymerase chain reaction (qPCR). POT1 mRNA levels, which were relatively stable, were significantly correlated with telomere length in gastric cancer cells and colon cancer cells, except for HT29 (P<0.01). POT1 v5 indexes were closely associated with radiosensitivity in colon cancer cells and gastric cancer cells (P<0.05). In conclusion, POT1 may be a good marker for the examination of cell-specific telomere length and radiosensitivity.
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Affiliation(s)
- Han Lei
- Hubei Key Laboratory of Tumor Biological Behaviors, Zhongnan Hospital, Wuhan University, Wuhan, Hubei 430071, P.R. China
| | - Fu-Xiang Zhou
- Hubei Key Laboratory of Tumor Biological Behaviors, Zhongnan Hospital, Wuhan University, Wuhan, Hubei 430071, P.R. China ; Department of Radiation and Medical Oncology, Zhongnan Hospital, Wuhan University, Wuhan, Hubei 430071, P.R. China ; Hubei Clinical Cancer Study Center, Wuhan University, Wuhan, Hubei 430071, P.R. China
| | - Hui Xu
- Hubei Key Laboratory of Tumor Biological Behaviors, Zhongnan Hospital, Wuhan University, Wuhan, Hubei 430071, P.R. China
| | - Xiao-Hong Peng
- Hubei Key Laboratory of Tumor Biological Behaviors, Zhongnan Hospital, Wuhan University, Wuhan, Hubei 430071, P.R. China
| | - Zhi-Guo Zhang
- Hubei Key Laboratory of Tumor Biological Behaviors, Zhongnan Hospital, Wuhan University, Wuhan, Hubei 430071, P.R. China
| | - Wen-Bo Wang
- Hubei Key Laboratory of Tumor Biological Behaviors, Zhongnan Hospital, Wuhan University, Wuhan, Hubei 430071, P.R. China
| | - Hai-Jun Yu
- Hubei Key Laboratory of Tumor Biological Behaviors, Zhongnan Hospital, Wuhan University, Wuhan, Hubei 430071, P.R. China ; Department of Radiation and Medical Oncology, Zhongnan Hospital, Wuhan University, Wuhan, Hubei 430071, P.R. China
| | - Cong-Hua Xie
- Hubei Key Laboratory of Tumor Biological Behaviors, Zhongnan Hospital, Wuhan University, Wuhan, Hubei 430071, P.R. China ; Department of Radiation and Medical Oncology, Zhongnan Hospital, Wuhan University, Wuhan, Hubei 430071, P.R. China
| | - Yun-Feng Zhou
- Hubei Key Laboratory of Tumor Biological Behaviors, Zhongnan Hospital, Wuhan University, Wuhan, Hubei 430071, P.R. China ; Department of Radiation and Medical Oncology, Zhongnan Hospital, Wuhan University, Wuhan, Hubei 430071, P.R. China ; Hubei Clinical Cancer Study Center, Wuhan University, Wuhan, Hubei 430071, P.R. China
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Robles-Espinoza CD, Velasco-Herrera MDC, Hayward NK, Adams DJ. Telomere-regulating genes and the telomere interactome in familial cancers. Mol Cancer Res 2015; 13:211-22. [PMID: 25244922 PMCID: PMC4278843 DOI: 10.1158/1541-7786.mcr-14-0305] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Telomeres are repetitive sequence structures at the ends of linear chromosomes that consist of double-stranded DNA repeats followed by a short single-stranded DNA protrusion. Telomeres need to be replicated in each cell cycle and protected from DNA-processing enzymes, tasks that cells execute using specialized protein complexes such as telomerase (that includes TERT), which aids in telomere maintenance and replication, and the shelterin complex, which protects chromosome ends. These complexes are also able to interact with a variety of other proteins, referred to as the telomere interactome, to fulfill their biological functions and control signaling cascades originating from telomeres. Given their essential role in genomic maintenance and cell-cycle control, germline mutations in telomere-regulating proteins and their interacting partners have been found to underlie a variety of diseases and cancer-predisposition syndromes. These syndromes can be characterized by progressively shortening telomeres, in which carriers can present with organ failure due to stem cell senescence among other characteristics, or can also present with long or unprotected telomeres, providing an alternative route for cancer formation. This review summarizes the critical roles that telomere-regulating proteins play in cell-cycle control and cell fate and explores the current knowledge on different cancer-predisposing conditions that have been linked to germline defects in these proteins and their interacting partners.
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Affiliation(s)
| | | | - Nicholas K Hayward
- Oncogenomics Laboratory, QIMR Berghofer Medical Research Institute, Herston, Brisbane, Queensland, Australia
| | - David J Adams
- Experimental Cancer Genetics, Wellcome Trust Sanger Institute, Hinxton, United Kingdom
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Ramanagoudr-Bhojappa R, Byrd AK, Dahl C, Raney KD. Yeast Pif1 accelerates annealing of complementary DNA strands. Biochemistry 2014; 53:7659-69. [PMID: 25393406 PMCID: PMC4263423 DOI: 10.1021/bi500746v] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Pif1 is a helicase involved in the maintenance of nuclear and mitochondrial genomes in eukaryotes. Here we report a new activity of Saccharomyces cerevisiae Pif1, annealing of complementary DNA strands. We identified preferred substrates for annealing as those that generate a duplex product with a single-stranded overhang relative to a blunt end duplex. Importantly, we show that Pif1 can anneal DNA in the presence of ATP and Mg(2+). Pif1-mediated annealing also occurs in the presence of single-stranded DNA binding proteins. Additionally, we show that partial duplex substrates with 3'-single-stranded overhangs such as those generated during double-strand break repair can be annealed by Pif1.
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Affiliation(s)
- Ramanagouda Ramanagoudr-Bhojappa
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences , Little Rock, Arkansas 72205, United States
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Dolgosheina EV, Jeng SCY, Panchapakesan SSS, Cojocaru R, Chen PSK, Wilson PD, Hawkins N, Wiggins PA, Unrau PJ. RNA mango aptamer-fluorophore: a bright, high-affinity complex for RNA labeling and tracking. ACS Chem Biol 2014; 9:2412-20. [PMID: 25101481 DOI: 10.1021/cb500499x] [Citation(s) in RCA: 296] [Impact Index Per Article: 29.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Because RNA lacks strong intrinsic fluorescence, it has proven challenging to track RNA molecules in real time. To address this problem and to allow the purification of fluorescently tagged RNA complexes, we have selected a high affinity RNA aptamer called RNA Mango. This aptamer binds a series of thiazole orange (fluorophore) derivatives with nanomolar affinity, while increasing fluorophore fluorescence by up to 1,100-fold. Visualization of RNA Mango by single-molecule fluorescence microscopy, together with injection and imaging of RNA Mango/fluorophore complex in C. elegans gonads demonstrates the potential for live-cell RNA imaging with this system. By inserting RNA Mango into a stem loop of the bacterial 6S RNA and biotinylating the fluorophore, we demonstrate that the aptamer can be used to simultaneously fluorescently label and purify biologically important RNAs. The high affinity and fluorescent properties of RNA Mango are therefore expected to simplify the study of RNA complexes.
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Affiliation(s)
- Elena V Dolgosheina
- Department of Molecular Biology and Biochemistry and ‡Department of Chemistry, Simon Fraser University , 8888 University Road, Burnaby, British Columbia V5A 1S6, Canada
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Acharya S, Kaul Z, Gocha AS, Martinez AR, Harris J, Parvin JD, Groden J. Association of BLM and BRCA1 during Telomere Maintenance in ALT Cells. PLoS One 2014; 9:e103819. [PMID: 25084169 PMCID: PMC4118958 DOI: 10.1371/journal.pone.0103819] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Accepted: 07/07/2014] [Indexed: 11/18/2022] Open
Abstract
Fifteen percent of tumors utilize recombination-based alternative lengthening of telomeres (ALT) to maintain telomeres. The mechanisms underlying ALT are unclear but involve several proteins involved in homologous recombination including the BLM helicase, mutated in Bloom's syndrome, and the BRCA1 tumor suppressor. Cells deficient in either BLM or BRCA1 have phenotypes consistent with telomere dysfunction. Although BLM associates with numerous DNA damage repair proteins including BRCA1 during DNA repair, the functional consequences of BLM-BRCA1 association in telomere maintenance are not completely understood. Our earlier work showed the involvement of BRCA1 in different mechanisms of ALT, and telomere shortening upon loss of BLM in ALT cells. In order to delineate their roles in telomere maintenance, we studied their association in telomere metabolism in cells using ALT. This work shows that BLM and BRCA1 co-localize with RAD50 at telomeres during S- and G2-phases of the cell cycle in immortalized human cells using ALT but not in cells using telomerase to maintain telomeres. Co-immunoprecipitation of BRCA1 and BLM is enhanced in ALT cells at G2. Furthermore, BRCA1 and BLM interact with RAD50 predominantly in S- and G2-phases, respectively. Biochemical assays demonstrate that full-length BRCA1 increases the unwinding rate of BLM three-fold in assays using a DNA substrate that models a forked structure composed of telomeric repeats. Our results suggest that BRCA1 participates in ALT through its interactions with RAD50 and BLM.
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Affiliation(s)
- Samir Acharya
- Department of Molecular Virology, Immunology and Medical Genetics, College of Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - Zeenia Kaul
- Department of Molecular Virology, Immunology and Medical Genetics, College of Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - April Sandy Gocha
- Department of Molecular Virology, Immunology and Medical Genetics, College of Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - Alaina R. Martinez
- Department of Molecular Virology, Immunology and Medical Genetics, College of Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - Julia Harris
- Department of Molecular Virology, Immunology and Medical Genetics, College of Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - Jeffrey D. Parvin
- Department of Molecular Virology, Immunology and Medical Genetics, College of Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - Joanna Groden
- Department of Molecular Virology, Immunology and Medical Genetics, College of Medicine, The Ohio State University, Columbus, Ohio, United States of America
- * E-mail:
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Physiological and pathological consequences of cellular senescence. Cell Mol Life Sci 2014; 71:4373-86. [PMID: 25080110 PMCID: PMC4207941 DOI: 10.1007/s00018-014-1691-3] [Citation(s) in RCA: 160] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Revised: 07/21/2014] [Accepted: 07/23/2014] [Indexed: 12/11/2022]
Abstract
Cellular senescence, a permanent state of cell cycle arrest accompanied by a complex phenotype, is an essential mechanism that limits tumorigenesis and tissue damage. In physiological conditions, senescent cells can be removed by the immune system, facilitating tumor suppression and wound healing. However, as we age, senescent cells accumulate in tissues, either because an aging immune system fails to remove them, the rate of senescent cell formation is elevated, or both. If senescent cells persist in tissues, they have the potential to paradoxically promote pathological conditions. Cellular senescence is associated with an enhanced pro-survival phenotype, which most likely promotes persistence of senescent cells in vivo. This phenotype may have evolved to favor facilitation of a short-term wound healing, followed by the elimination of senescent cells by the immune system. In this review, we provide a perspective on the triggers, mechanisms and physiological as well as pathological consequences of senescent cells.
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León-Ortiz AM, Svendsen J, Boulton SJ. Metabolism of DNA secondary structures at the eukaryotic replication fork. DNA Repair (Amst) 2014; 19:152-62. [PMID: 24815912 DOI: 10.1016/j.dnarep.2014.03.016] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
DNA secondary structures are largely advantageous for numerous cellular processes but can pose specific threats to the progression of the replication machinery and therefore genome duplication and cell division. A number of specialized enzymes dismantle these structures to allow replication fork progression to proceed faithfully. In this review, we discuss the in vitro and in vivo data that has lead to the identification of these enzymes in eukaryotes, and the evidence that suggests that they act specifically at replication forks to resolve secondary structures. We focus on the role of helicases, which catalyze the dissociation of nucleotide complexes, and on the role of nucleases, which cleave secondary structures to allow replication fork progression at the expense of local rearrangements. Finally, we discuss outstanding questions in terms of dismantling DNA secondary structures, as well as the interplay between diverse enzymes that act upon specific types of structures.
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Affiliation(s)
- Ana María León-Ortiz
- DNA Damage Response Laboratory, London Research Institute, Cancer Research UK, Clare Hall, South Mimms EN6 3LD, UK
| | - Jennifer Svendsen
- DNA Damage Response Laboratory, London Research Institute, Cancer Research UK, Clare Hall, South Mimms EN6 3LD, UK
| | - Simon J Boulton
- DNA Damage Response Laboratory, London Research Institute, Cancer Research UK, Clare Hall, South Mimms EN6 3LD, UK.
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