1
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Romero-Zamora D, Hayashi MT. A non-catalytic N-terminus domain of WRN prevents mitotic telomere deprotection. Sci Rep 2023; 13:645. [PMID: 36635307 PMCID: PMC9837040 DOI: 10.1038/s41598-023-27598-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Accepted: 01/04/2023] [Indexed: 01/14/2023] Open
Abstract
Telomeric ends form a loop structure (T-loop) necessary for the repression of ATM kinase activation throughout the normal cell cycle. However, cells undergoing a prolonged mitotic arrest are prone to lose the T-loop, resulting in Aurora B kinase-dependent mitotic telomere deprotection, which was proposed as an anti-tumor mechanism that eliminates precancerous cells from the population. The mechanism of mitotic telomere deprotection has not been elucidated. Here, we show that WRN, a RECQ helicase family member, can suppress mitotic telomere deprotection independently of its exonuclease and helicase activities. Truncation of WRN revealed that N-terminus amino acids 168-333, a region that contains a coiled-coil motif, is sufficient to suppress mitotic telomere deprotection without affecting both mitotic Aurora B-dependent spindle checkpoint and ATM kinase activity. The suppressive activity of the WRN168-333 fragment is diminished in cells partially depleted of TRF2, while WRN is required for complete suppression of mitotic telomere deprotection by TRF2 overexpression. Finally, we found that phosphomimetic but not alanine mutations of putative Aurora B target sites in the WRN168-333 fragment abolished its suppressive effect. Our findings reveal a non-enzymatic function of WRN, which may be regulated by phosphorylation in cells undergoing mitotic arrest. We propose that WRN enhances the protective function of TRF2 to counteract the hypothetical pathway that resolves the mitotic T-loop.
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Affiliation(s)
- Diana Romero-Zamora
- grid.258799.80000 0004 0372 2033Graduate School of Biostudies, Kyoto University, Yoshida-Konoe, Sakyo, Kyoto, 606-8501 Japan ,grid.258799.80000 0004 0372 2033IFOM-KU Joint Research Laboratory, Graduate School of Medicine, Kyoto University, Yoshida-Konoe, Sakyo, Kyoto, 606-8501 Japan
| | - Makoto T. Hayashi
- grid.258799.80000 0004 0372 2033IFOM-KU Joint Research Laboratory, Graduate School of Medicine, Kyoto University, Yoshida-Konoe, Sakyo, Kyoto, 606-8501 Japan ,IFOM ETS, The AIRC Institute of Molecular Oncology, Via Adamello 16, 20139 Milan, Italy
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2
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Ikematsu Y, Izumi M, Katahira K, Ueno T, Moriuchi Y, Ose M, Noda N, Hara M, Otsuka J, Wakamatsu K, Kawasaki M. Combination immunotherapy of nivolumab plus ipilimumab in a lung cancer patient with Werner syndrome; a case report. Respir Med Case Rep 2022; 37:101642. [PMID: 35360361 PMCID: PMC8960968 DOI: 10.1016/j.rmcr.2022.101642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 03/14/2022] [Accepted: 03/21/2022] [Indexed: 10/26/2022] Open
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3
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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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4
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Sharma R, Lewis S, Wlodarski MW. DNA Repair Syndromes and Cancer: Insights Into Genetics and Phenotype Patterns. Front Pediatr 2020; 8:570084. [PMID: 33194896 PMCID: PMC7644847 DOI: 10.3389/fped.2020.570084] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Accepted: 09/18/2020] [Indexed: 12/15/2022] Open
Abstract
DNA damage response is essential to human physiology. A broad spectrum of pathologies are displayed by individuals carrying monoallelic or biallelic loss-of-function mutations in DNA damage repair genes. DNA repair syndromes with biallelic disturbance of essential DNA damage response pathways manifest early in life with multi-systemic involvement and a high propensity for hematologic and solid cancers, as well as bone marrow failure. In this review, we describe classic biallelic DNA repair cancer syndromes arising from faulty single- and double-strand DNA break repair, as well as dysfunctional DNA helicases. These clinical entities include xeroderma pigmentosum, constitutional mismatch repair deficiency, ataxia telangiectasia, Nijmegen breakage syndrome, deficiencies of DNA ligase IV, NHEJ/Cernunnos, and ERCC6L2, as well as Bloom, Werner, and Rothmund-Thompson syndromes. To give an in-depth understanding of these disorders, we provide historical overview and discuss the interplay between complex biology and heterogeneous clinical manifestations.
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Affiliation(s)
- Richa Sharma
- Department of Hematology, St. Jude Children's Research Hospital, Memphis, TN, United States.,Department of Oncology, St. Jude Children's Research Hospital, Memphis, TN, United States
| | - Sara Lewis
- Department of Hematology, St. Jude Children's Research Hospital, Memphis, TN, United States
| | - Marcin W Wlodarski
- Department of Hematology, St. Jude Children's Research Hospital, Memphis, TN, United States.,Division of Pediatric Hematology and Oncology, Department of Pediatrics and Adolescent Medicine, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
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5
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Abstract
Many recent advances have emerged in the telomere and telomerase fields. This Timeline article highlights the key advances that have expanded our views on the mechanistic underpinnings of telomeres and telomerase and their roles in ageing and disease. Three decades ago, the classic view was that telomeres protected the natural ends of linear chromosomes and that telomerase was a specific telomere-terminal transferase necessary for the replication of chromosome ends in single-celled organisms. While this concept is still correct, many diverse fields associated with telomeres and telomerase have substantially matured. These areas include the discovery of most of the key molecular components of telomerase, implications for limits to cellular replication, identification and characterization of human genetic disorders that result in premature telomere shortening, the concept that inhibiting telomerase might be a successful therapeutic strategy and roles for telomeres in regulating gene expression. We discuss progress in these areas and conclude with challenges and unanswered questions in the field.
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Affiliation(s)
- Jerry W Shay
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX, USA.
| | - Woodring E Wright
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX, USA
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6
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Armando RG, Mengual Gomez DL, Maggio J, Sanmartin MC, Gomez DE. Telomeropathies: Etiology, diagnosis, treatment and follow-up. Ethical and legal considerations. Clin Genet 2019; 96:3-16. [PMID: 30820928 DOI: 10.1111/cge.13526] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 02/12/2019] [Accepted: 02/26/2019] [Indexed: 12/13/2022]
Abstract
Telomeropathies involve a wide variety of infrequent genetic diseases caused by mutations in the telomerase maintenance mechanism or the DNA damage response (DDR) system. They are considered a family of rare diseases that often share causes, molecular mechanisms and symptoms. Generally, these diseases are not diagnosed until the symptoms are advanced, diminishing the survival time of patients. Although several related syndromes may still be unrecognized this work describes those that are known, highlighting that because they are rare diseases, physicians should be trained in their early diagnosis. The etiology and diagnosis are discussed for each telomeropathy and the treatments when available, along with a new classification of this group of diseases. Ethical and legal issues related to this group of diseases are also considered.
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Affiliation(s)
- Romina G Armando
- Laboratory of Molecular Oncology, Universidad Nacional de Quilmes, Buenos Aires, Argentina
| | - Diego L Mengual Gomez
- Laboratory of Molecular Oncology, Universidad Nacional de Quilmes, Buenos Aires, Argentina
| | - Julián Maggio
- Laboratory of Molecular Oncology, Universidad Nacional de Quilmes, Buenos Aires, Argentina
| | - María C Sanmartin
- Laboratory of Molecular Oncology, Universidad Nacional de Quilmes, Buenos Aires, Argentina
| | - Daniel E Gomez
- Laboratory of Molecular Oncology, Universidad Nacional de Quilmes, Buenos Aires, Argentina
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7
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Lidzbarsky G, Gutman D, Shekhidem HA, Sharvit L, Atzmon G. Genomic Instabilities, Cellular Senescence, and Aging: In Vitro, In Vivo and Aging-Like Human Syndromes. Front Med (Lausanne) 2018; 5:104. [PMID: 29719834 PMCID: PMC5913290 DOI: 10.3389/fmed.2018.00104] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2018] [Accepted: 03/29/2018] [Indexed: 12/20/2022] Open
Abstract
As average life span and elderly people prevalence in the western world population is gradually increasing, the incidence of age-related diseases such as cancer, heart diseases, diabetes, and dementia is increasing, bearing social and economic consequences worldwide. Understanding the molecular basis of aging-related processes can help extend the organism’s health span, i.e., the life period in which the organism is free of chronic diseases or decrease in basic body functions. During the last few decades, immense progress was made in the understanding of major components of aging and healthy aging biology, including genomic instability, telomere attrition, epigenetic changes, proteostasis, nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, and intracellular communications. This progress has been made by three spear-headed strategies: in vitro (cell and tissue culture from various sources), in vivo (includes diverse model and non-model organisms), both can be manipulated and translated to human biology, and the study of aging-like human syndromes and human populations. Herein, we will focus on current repository of genomic “senescence” stage of aging, which includes health decline, structural changes of the genome, faulty DNA damage response and DNA damage, telomere shortening, and epigenetic alterations. Although aging is a complex process, many of the “hallmarks” of aging are directly related to DNA structure and function. This review will illustrate the variety of these studies, done in in vitro, in vivo and human levels, and highlight the unique potential and contribution of each research level and eventually the link between them.
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Affiliation(s)
| | - Danielle Gutman
- Department of Human Biology, University of Haifa, Haifa, Israel
| | | | - Lital Sharvit
- Department of Human Biology, University of Haifa, Haifa, Israel
| | - Gil Atzmon
- Department of Human Biology, University of Haifa, Haifa, Israel
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8
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RecQ and Fe-S helicases have unique roles in DNA metabolism dictated by their unwinding directionality, substrate specificity, and protein interactions. Biochem Soc Trans 2017; 46:77-95. [PMID: 29273621 DOI: 10.1042/bst20170044] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 11/15/2017] [Accepted: 11/17/2017] [Indexed: 12/11/2022]
Abstract
Helicases are molecular motors that play central roles in nucleic acid metabolism. Mutations in genes encoding DNA helicases of the RecQ and iron-sulfur (Fe-S) helicase families are linked to hereditary disorders characterized by chromosomal instabilities, highlighting the importance of these enzymes. Moreover, mono-allelic RecQ and Fe-S helicase mutations are associated with a broad spectrum of cancers. This review will discuss and contrast the specialized molecular functions and biological roles of RecQ and Fe-S helicases in DNA repair, the replication stress response, and the regulation of gene expression, laying a foundation for continued research in these important areas of study.
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9
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Yalçin Z, Selenz C, Jacobs JJL. Ubiquitination and SUMOylation in Telomere Maintenance and Dysfunction. Front Genet 2017; 8:67. [PMID: 28588610 PMCID: PMC5440461 DOI: 10.3389/fgene.2017.00067] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Accepted: 05/10/2017] [Indexed: 12/14/2022] Open
Abstract
Telomeres are essential nucleoprotein structures at linear chromosomes that maintain genome integrity by protecting chromosome ends from being recognized and processed as damaged DNA. In addition, they limit the cell’s proliferative capacity, as progressive loss of telomeric DNA during successive rounds of cell division eventually causes a state of telomere dysfunction that prevents further cell division. When telomeres become critically short, the cell elicits a DNA damage response resulting in senescence, apoptosis or genomic instability, thereby impacting on aging and tumorigenesis. Over the past years substantial progress has been made in understanding the role of post-translational modifications in telomere-related processes, including telomere maintenance, replication and dysfunction. This review will focus on recent findings that establish an essential role for ubiquitination and SUMOylation at telomeres.
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Affiliation(s)
- Zeliha Yalçin
- Department of Molecular Oncology, Netherlands Cancer InstituteAmsterdam, Netherlands
| | - Carolin Selenz
- Department of Molecular Oncology, Netherlands Cancer InstituteAmsterdam, Netherlands
| | - Jacqueline J L Jacobs
- Department of Molecular Oncology, Netherlands Cancer InstituteAmsterdam, Netherlands
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10
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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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11
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Oshima J, Sidorova JM, Monnat RJ. Werner syndrome: Clinical features, pathogenesis and potential therapeutic interventions. Ageing Res Rev 2017; 33:105-114. [PMID: 26993153 PMCID: PMC5025328 DOI: 10.1016/j.arr.2016.03.002] [Citation(s) in RCA: 161] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 02/09/2016] [Accepted: 03/11/2016] [Indexed: 12/20/2022]
Abstract
Werner syndrome (WS) is a prototypical segmental progeroid syndrome characterized by multiple features consistent with accelerated aging. It is caused by null mutations of the WRN gene, which encodes a member of the RECQ family of DNA helicases. A unique feature of the WRN helicase is the presence of an exonuclease domain in its N-terminal region. Biochemical and cell biological studies during the past decade have demonstrated involvements of the WRN protein in multiple DNA transactions, including DNA repair, recombination, replication and transcription. A role of the WRN protein in telomere maintenance could explain many of the WS phenotypes. Recent discoveries of new progeroid loci found in atypical Werner cases continue to support the concept of genomic instability as a major mechanism of biological aging. Based on these biological insights, efforts are underway to develop therapeutic interventions for WS and related progeroid syndromes.
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Affiliation(s)
- Junko Oshima
- Department of Pathology, University of Washington, Seattle, WA 98195, USA; Department of Medicine, Chiba University, Chiba, Japan.
| | - Julia M Sidorova
- Department of Pathology, University of Washington, Seattle, WA 98195, USA
| | - Raymond J Monnat
- Department of Pathology, University of Washington, Seattle, WA 98195, USA; Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
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12
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Telomere-associated aging disorders. Ageing Res Rev 2017; 33:52-66. [PMID: 27215853 PMCID: PMC9926533 DOI: 10.1016/j.arr.2016.05.009] [Citation(s) in RCA: 96] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Revised: 05/17/2016] [Accepted: 05/19/2016] [Indexed: 01/25/2023]
Abstract
Telomeres are dynamic nucleoprotein-DNA structures that cap and protect linear chromosome ends. Several monogenic inherited diseases that display features of human premature aging correlate with shortened telomeres, and are referred to collectively as telomeropathies. These disorders have overlapping symptoms and a common underlying mechanism of telomere dysfunction, but also exhibit variable symptoms and age of onset, suggesting they fall along a spectrum of disorders. Primary telomeropathies are caused by defects in the telomere maintenance machinery, whereas secondary telomeropathies have some overlapping symptoms with primary telomeropathies, but are generally caused by mutations in DNA repair proteins that contribute to telomere preservation. Here we review both the primary and secondary telomeropathies, discuss potential mechanisms for tissue specificity and age of onset, and highlight outstanding questions in the field and future directions toward elucidating disease etiology and developing therapeutic strategies.
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13
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da Silva Neto Trajano LA, Stumbo AC, da Silva CL, Mencalha AL, Fonseca AS. Low-level infrared laser modulates muscle repair and chromosome stabilization genes in myoblasts. Lasers Med Sci 2016; 31:1161-7. [PMID: 27220530 DOI: 10.1007/s10103-016-1956-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 05/02/2016] [Indexed: 10/21/2022]
Abstract
Infrared laser therapy is used for skeletal muscle repair based on its biostimulative effect on satellite cells. However, shortening of telomere length limits regenerative potential in satellite cells, which occurs after each cell division cycle. Also, laser therapy could be more effective on non-physiologic tissues. This study evaluated low-level infrared laser exposure effects on mRNA expression from muscle injury repair and telomere stabilization genes in myoblasts in normal and stressful conditions. Laser fluences were those used in clinical protocols. C2C12 myoblast cultures were exposed to low-level infrared laser (10, 35, and 70 J/cm(2)) in standard or normal (10 %) and reduced (2 %) fetal bovine serum concentrations; total RNA was extracted for mRNA expression evaluation from muscle injury repair (MyoD and Pax7) and chromosome stabilization (TRF1 and TRF2) genes by real time quantitative polymerization chain reaction. Data show that low-level infrared laser increases the expression of MyoD and Pax7 in 10 J/cm(2) fluence, TRF1 expression in all fluences, and TRF2 expression in 70 J/cm(2) fluence in both 10 and 2 % fetal bovine serum. Low-level infrared laser increases mRNA expression from genes related to muscle repair and telomere stabilization in myoblasts in standard or normal and stressful conditions.
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Affiliation(s)
- Larissa Alexsandra da Silva Neto Trajano
- Laboratório de Pesquisa em Células Tronco, Departamento de Histologia e Embriologia, Instituto de Biologia Roberto Alcantara Gomes, Universidade do Estado do Rio de Janeiro, Avenida 28 de Setembro, 87, fundos, Vila Isabel, Rio de Janeiro, 20551030, Brazil
| | - Ana Carolina Stumbo
- Laboratório de Pesquisa em Células Tronco, Departamento de Histologia e Embriologia, Instituto de Biologia Roberto Alcantara Gomes, Universidade do Estado do Rio de Janeiro, Avenida 28 de Setembro, 87, fundos, Vila Isabel, Rio de Janeiro, 20551030, Brazil
| | - Camila Luna da Silva
- Laboratório de Pesquisa em Células Tronco, Departamento de Histologia e Embriologia, Instituto de Biologia Roberto Alcantara Gomes, Universidade do Estado do Rio de Janeiro, Avenida 28 de Setembro, 87, fundos, Vila Isabel, Rio de Janeiro, 20551030, Brazil
| | - Andre Luiz Mencalha
- Departamento de Biofísica e Biometria, Instituto de Biologia Roberto Alcantara Gomes, Universidade do Estado do Rio de Janeiro, Avenida 28 de Setembro, 87, fundos, 4° andar, Vila Isabel, Rio de Janeiro, 20551030, Brazil
| | - Adenilson S Fonseca
- Departamento de Biofísica e Biometria, Instituto de Biologia Roberto Alcantara Gomes, Universidade do Estado do Rio de Janeiro, Avenida 28 de Setembro, 87, fundos, 4° andar, Vila Isabel, Rio de Janeiro, 20551030, Brazil. .,Departamento de Ciências Fisiológicas, Instituto Biomédico, Universidade Federal do Estado do Rio de Janeiro, Rua Frei Caneca, 94, Rio de Janeiro, 20211040, Brazil.
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14
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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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15
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Martínez P, Blasco MA. Replicating through telomeres: a means to an end. Trends Biochem Sci 2015; 40:504-15. [PMID: 26188776 DOI: 10.1016/j.tibs.2015.06.003] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Revised: 06/08/2015] [Accepted: 06/12/2015] [Indexed: 02/07/2023]
Abstract
Proper replication of the telomeric DNA at chromosome ends is critical for preserving genome integrity. Yet, telomeres present challenges for the replication machinery, such as their repetitive and heterochromatic nature and their potential to form non-Watson-Crick structures as well as the fact that they are transcribed. Numerous telomere-bound proteins are required to facilitate progression of the replication fork throughout telomeric DNA. In particular, shelterin plays crucial functions in telomere length regulation, protection of telomeres from nuclease degradation, control of DNA damage response at telomeres, and the recruitment of associated factors required for telomere DNA processing and replication. In this review we discuss the recently uncovered functions of mammalian telomere-specific and telomere-associated proteins that facilitate proper telomere replication.
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Affiliation(s)
- Paula Martínez
- Telomeres and Telomerase Group, Molecular Oncology Program, Spanish National Cancer Research Centre (CNIO), Madrid E-28029, Spain
| | - Maria A Blasco
- Telomeres and Telomerase Group, Molecular Oncology Program, Spanish National Cancer Research Centre (CNIO), Madrid E-28029, Spain.
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16
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Chatterjee S, Zagelbaum J, Savitsky P, Sturzenegger A, Huttner D, Janscak P, Hickson ID, Gileadi O, Rothenberg E. Mechanistic insight into the interaction of BLM helicase with intra-strand G-quadruplex structures. Nat Commun 2014; 5:5556. [PMID: 25418155 PMCID: PMC4243535 DOI: 10.1038/ncomms6556] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Accepted: 10/14/2014] [Indexed: 01/15/2023] Open
Abstract
Bloom syndrome is an autosomal recessive disorder caused by mutations in the RecQ family helicase BLM that is associated with growth retardation and predisposition to cancer. BLM helicase has a high specificity for non-canonical G-quadruplex (G4) DNA structures, which are formed by G-rich DNA strands and play an important role in the maintenance of genomic integrity. Here, we used single-molecule FRET to define the mechanism of interaction of BLM helicase with intra-stranded G4 structures. We show that the activity of BLM is substrate dependent, and highly regulated by a short ssDNA segment that separates the G4 motif from dsDNA. We demonstrate cooperativity between the RQC and HRDC domains of BLM during binding and unfolding of the G4 structure, where the RQC domain interaction with G4 is stabilized by HRDC binding to ssDNA. We present a model that proposes a unique role for G4 structures in modulating the activity of DNA processing enzymes.
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Affiliation(s)
- Sujoy Chatterjee
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, MSB 394, 550 First Avenue, New York, New York 10016, USA
| | - Jennifer Zagelbaum
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, MSB 394, 550 First Avenue, New York, New York 10016, USA
| | - Pavel Savitsky
- Genome Integrity group, Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, UK
| | - Andreas Sturzenegger
- Institute of Molecular Cancer Research, University of Zurich, CH-8057 Zurich, Switzerland
| | - Diana Huttner
- 1] NovoNordisk Foundation Center for Protein Research, University of Copenhagen, 2200 Copenhagen, Denmark [2] Department of Cellular and Molecular Medicine, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Pavel Janscak
- Institute of Molecular Cancer Research, University of Zurich, CH-8057 Zurich, Switzerland
| | - Ian D Hickson
- Department of Cellular and Molecular Medicine, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Opher Gileadi
- Genome Integrity group, Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, UK
| | - Eli Rothenberg
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, MSB 394, 550 First Avenue, New York, New York 10016, USA
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17
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Bower BD, Griffith JD. TRF1 and TRF2 differentially modulate Rad51-mediated telomeric and nontelomeric displacement loop formation in vitro. Biochemistry 2014; 53:5485-95. [PMID: 25115914 PMCID: PMC4151696 DOI: 10.1021/bi5006249] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
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A growing
body of literature suggests that the homologous recombination/repair
(HR) pathway cooperates with components of the shelterin complex to
promote both telomere maintenance and nontelomeric HR. This may be
due to the ability of both HR and shelterin proteins to promote strand
invasion, wherein a single-stranded DNA (ssDNA) substrate base pairs
with a homologous double-stranded DNA (dsDNA) template displacing
a loop of ssDNA (D-loop). Rad51 recombinase catalyzes D-loop formation
during HR, and telomere repeat binding factor 2 (TRF2) catalyzes the
formation of a telomeric D-loop that stabilizes a looped structure
in telomeric DNA (t-loop) that may facilitate telomere protection.
We have characterized this functional interaction in vitro using a fluorescent D-loop assay measuring the incorporation of
Cy3-labeled 90-nucleotide telomeric and nontelomeric substrates into
telomeric and nontelomeric plasmid templates. We report that preincubation
of a telomeric template with TRF2 inhibits the ability of Rad51 to
promote telomeric D-loop formation upon preincubation with a telomeric
substrate. This suggests Rad51 does not facilitate t-loop formation
and suggests a mechanism whereby TRF2 can inhibit HR at telomeres.
We also report a TRF2 mutant lacking the dsDNA binding domain promotes
Rad51-mediated nontelomeric D-loop formation, possibly explaining
how TRF2 promotes nontelomeric HR. Finally, we report telomere repeat
binding factor 1 (TRF1) promotes Rad51-mediated telomeric D-loop formation,
which may facilitate HR-mediated replication fork restart and explain
why TRF1 is required for efficient telomere replication.
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Affiliation(s)
- Brian D Bower
- Curriculum in Genetics and Molecular Biology, University of North Carolina , Chapel Hill, North Carolina 27599, United States
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