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Nassour J, Przetocka S, Karlseder J. Telomeres as hotspots for innate immunity and inflammation. DNA Repair (Amst) 2024; 133:103591. [PMID: 37951043 PMCID: PMC10842095 DOI: 10.1016/j.dnarep.2023.103591] [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: 07/24/2023] [Revised: 10/05/2023] [Accepted: 10/24/2023] [Indexed: 11/13/2023]
Abstract
Aging is marked by the gradual accumulation of deleterious changes that disrupt organ function, creating an altered physiological state that is permissive for the onset of prevalent human diseases. While the exact mechanisms governing aging remain a subject of ongoing research, there are several cellular and molecular hallmarks that contribute to this biological process. This review focuses on two factors, namely telomere dysfunction and inflammation, which have emerged as crucial contributors to the aging process. We aim to discuss the mechanistic connections between these two distinct hallmarks and provide compelling evidence highlighting the loss of telomere protection as a driver of pro-inflammatory states associated with aging. By reevaluating the interplay between telomeres, innate immunity, and inflammation, we present novel perspectives on the etiology of aging and its associated diseases.
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Affiliation(s)
- Joe Nassour
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, 12801 E. 17th Ave, Aurora, CO 80045, USA; The Salk Institute for Biological Studies, 10010 North Torrey Pines Rd, La Jolla, CA 92037, USA
| | - Sara Przetocka
- The Salk Institute for Biological Studies, 10010 North Torrey Pines Rd, La Jolla, CA 92037, USA
| | - Jan Karlseder
- The Salk Institute for Biological Studies, 10010 North Torrey Pines Rd, La Jolla, CA 92037, USA.
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2
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Li B. Telomere maintenance in African trypanosomes. Front Mol Biosci 2023; 10:1302557. [PMID: 38074093 PMCID: PMC10704157 DOI: 10.3389/fmolb.2023.1302557] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Accepted: 11/15/2023] [Indexed: 02/12/2024] Open
Abstract
Telomere maintenance is essential for genome integrity and chromosome stability in eukaryotic cells harboring linear chromosomes, as telomere forms a specialized structure to mask the natural chromosome ends from DNA damage repair machineries and to prevent nucleolytic degradation of the telomeric DNA. In Trypanosoma brucei and several other microbial pathogens, virulence genes involved in antigenic variation, a key pathogenesis mechanism essential for host immune evasion and long-term infections, are located at subtelomeres, and expression and switching of these major surface antigens are regulated by telomere proteins and the telomere structure. Therefore, understanding telomere maintenance mechanisms and how these pathogens achieve a balance between stability and plasticity at telomere/subtelomere will help develop better means to eradicate human diseases caused by these pathogens. Telomere replication faces several challenges, and the "end replication problem" is a key obstacle that can cause progressive telomere shortening in proliferating cells. To overcome this challenge, most eukaryotes use telomerase to extend the G-rich telomere strand. In addition, a number of telomere proteins use sophisticated mechanisms to coordinate the telomerase-mediated de novo telomere G-strand synthesis and the telomere C-strand fill-in, which has been extensively studied in mammalian cells. However, we recently discovered that trypanosomes lack many telomere proteins identified in its mammalian host that are critical for telomere end processing. Rather, T. brucei uses a unique DNA polymerase, PolIE that belongs to the DNA polymerase A family (E. coli DNA PolI family), to coordinate the telomere G- and C-strand syntheses. In this review, I will first briefly summarize current understanding of telomere end processing in mammals. Subsequently, I will describe PolIE-mediated coordination of telomere G- and C-strand synthesis in T. brucei and implication of this recent discovery.
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Affiliation(s)
- Bibo Li
- Center for Gene Regulation in Health and Disease, Department of Biological, Geological, and Environmental Sciences, College of Arts and Sciences, Cleveland State University, Cleveland, OH, United States
- Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH, United States
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, United States
- Center for RNA Science and Therapeutics, Case Western Reserve University, Cleveland, OH, United States
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3
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Lee J, Lee J, Sohn EJ, Taglialatela A, O’Sullivan RJ, Ciccia A, Min J. Extrachromosomal Telomeres Derived from Excessive Strand Displacements. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.31.551186. [PMID: 37577643 PMCID: PMC10418088 DOI: 10.1101/2023.07.31.551186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
Alternative Lengthening of Telomeres (ALT) is a telomere maintenance mechanism mediated by break-induced replication (BIR), evident in approximately 15% of human cancers. A characteristic feature of ALT cancers is the presence of C-circles, circular single-stranded telomeric DNAs composed of C-rich sequences. Despite the fact that extrachromosomal C-rich single-stranded DNAs (ssDNAs), unique to ALT cells, are considered potential precursors of C-circles, their generation process remains undefined. Here, we introduce a highly sensitive method to detect single stranded telomeric DNA, called 4SET (Strand-Specific Southern-blot for Single-stranded Extrachromosomal Telomeres) assay. Utilizing 4SET, we are able to capture C-rich single stranded DNAs that are near 200 to 1500 nucleotides in size. Both linear C-rich ssDNAs and C-circles are abundant in the fractions of cytoplasm and nucleoplasm, which supports the idea that linear C-rich ssDNA accumulation may indeed precede C-circle formation. We also found that C-rich ssDNAs originate during Okazaki fragment processing during lagging strand DNA synthesis. The generation of C-rich ssDNA requires CST-PP (CTC1/STN1/TEN1-PRIMASE-Polymerase alpha) complex-mediated priming of the C-strand DNA synthesis and subsequent excessive strand displacement of the C-rich strand mediated by the DNA Polymerase delta and the BLM helicase. Our work proposes a new model for the generation of C-rich ssDNAs and C-circles during ALT-mediated telomere elongation.
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Affiliation(s)
- Junyeop Lee
- Institute for Cancer Genetics, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Jina Lee
- Institute for Cancer Genetics, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
- Department of Pathology and Cell Biology, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Eric J. Sohn
- Institute for Cancer Genetics, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Angelo Taglialatela
- Department of Genetics and Development, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Roderick J. O’Sullivan
- Department of Pharmacology and Chemical Biology, UPMC Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA, USA
| | - Alberto Ciccia
- Institute for Cancer Genetics, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
- Department of Genetics and Development, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
- Herbert Irving Comprehensive Cancer Center, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Jaewon Min
- Institute for Cancer Genetics, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
- Department of Pathology and Cell Biology, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
- Herbert Irving Comprehensive Cancer Center, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
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4
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Chitwood DG, Uy L, Fu W, Klaubert SR, Harcum SW, Saski CA. Dynamics of Amino Acid Metabolism, Gene Expression, and Circulomics in a Recombinant Chinese Hamster Ovary Cell Line Adapted to Moderate and High Levels of Extracellular Lactate. Genes (Basel) 2023; 14:1576. [PMID: 37628627 PMCID: PMC10454118 DOI: 10.3390/genes14081576] [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: 07/10/2023] [Revised: 07/20/2023] [Accepted: 07/21/2023] [Indexed: 08/27/2023] Open
Abstract
The accumulation of metabolic wastes in cell cultures can diminish product quality, reduce productivity, and trigger apoptosis. The limitation or removal of unintended waste products from Chinese hamster ovary (CHO) cell cultures has been attempted through multiple process and genetic engineering avenues with varied levels of success. One study demonstrated a simple method to reduce lactate and ammonia production in CHO cells with adaptation to extracellular lactate; however, the mechanism behind adaptation was not certain. To address this profound gap, this study characterizes the phenotype of a recombinant CHO K-1 cell line that was gradually adapted to moderate and high levels of extracellular lactate and examines the genomic content and role of extrachromosomal circular DNA (eccDNA) and gene expression on the adaptation process. More than 500 genes were observed on eccDNAs. Notably, more than 1000 genes were observed to be differentially expressed at different levels of lactate adaptation, while only 137 genes were found to be differentially expressed between unadapted cells and cells adapted to grow in high levels of lactate; this suggests stochastic switching as a potential stress adaptation mechanism in CHO cells. Further, these data suggest alanine biosynthesis as a potential stress-mitigation mechanism for excess lactate in CHO cells.
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Affiliation(s)
- Dylan G. Chitwood
- Department of Bioengineering, Clemson University, Clemson, SC 29634, USA; (D.G.C.); (L.U.); (S.W.H.)
| | - Lisa Uy
- Department of Bioengineering, Clemson University, Clemson, SC 29634, USA; (D.G.C.); (L.U.); (S.W.H.)
| | - Wanfang Fu
- Department of Plant and Environmental Sciences, Clemson University, Clemson, SC 29634, USA;
| | - Stephanie R. Klaubert
- Department of Chemical & Biomolecular Engineering, Clemson University, Clemson, SC 29634, USA;
| | - Sarah W. Harcum
- Department of Bioengineering, Clemson University, Clemson, SC 29634, USA; (D.G.C.); (L.U.); (S.W.H.)
- Department of Chemical & Biomolecular Engineering, Clemson University, Clemson, SC 29634, USA;
| | - Christopher A. Saski
- Department of Plant and Environmental Sciences, Clemson University, Clemson, SC 29634, USA;
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5
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Jones CY, Williams CL, Moreno SP, Morris DK, Mondello C, Karlseder J, Bertuch AA. Hyperextended telomeres promote formation of C-circle DNA in telomerase positive human cells. J Biol Chem 2023; 299:104665. [PMID: 37003504 PMCID: PMC10235436 DOI: 10.1016/j.jbc.2023.104665] [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: 01/26/2023] [Revised: 03/17/2023] [Accepted: 03/18/2023] [Indexed: 04/01/2023] Open
Abstract
Telomere length maintenance is crucial to cancer cell immortality. Up to 15% of cancers utilize a telomerase-independent, recombination-based mechanism termed alternative lengthening of telomeres (ALT). Currently, the primary ALT biomarker is the C-circle, a type of circular DNA with extrachromosomal telomere repeats (cECTRs). How C-circles form is not well characterized. We investigated C-circle formation in the human cen3tel cell line, a long-telomere, telomerase+ (LTT+) cell line with progressively hyper-elongated telomeres (up to ∼100 kb). cECTR signal was observed in 2D gels and C-circle assays but not t-circle assays, which also detect circular DNA with extrachromosomal telomere repeats. Telomerase activity and C-circle signal were not separable in the analysis of clonal populations, consistent with C-circle production occurring within telomerase+ cells. We observed similar cECTR results in two other LTT+ cell lines, HeLa1.3 (∼23 kb telomeres) and HeLaE1 (∼50 kb telomeres). In LTT+ cells, telomerase activity did not directly impact C-circle signal; instead, C-circle signal correlated with telomere length. LTT+ cell lines were less sensitive to hydroxyurea than ALT+ cell lines, suggesting that ALT status is a stronger contributor to replication stress levels than telomere length. Additionally, the DNA repair-associated protein FANCM did not suppress C-circles in LTT+ cells as it does in ALT+ cells. Thus, C-circle formation may be driven by telomere length, independently of telomerase and replication stress, highlighting limitations of C-circles as a stand-alone ALT biomarker.
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Affiliation(s)
- Celina Y Jones
- Division of Hematology/Oncology, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA; Texas Children's Cancer Center, Texas Children's Hospital, Houston, Texas, USA
| | - Christopher L Williams
- Division of Hematology/Oncology, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA; Texas Children's Cancer Center, Texas Children's Hospital, Houston, Texas, USA
| | - Sara Priego Moreno
- Molecular and Cell Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California, USA
| | - Danna K Morris
- Division of Hematology/Oncology, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA; Texas Children's Cancer Center, Texas Children's Hospital, Houston, Texas, USA
| | - Chiara Mondello
- Institute of Molecular Genetics, Luigi Luca Cavalli-Sforza, National Research Council, Pavia, Italy
| | - Jan Karlseder
- Molecular and Cell Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California, USA
| | - Alison A Bertuch
- Division of Hematology/Oncology, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA; Texas Children's Cancer Center, Texas Children's Hospital, Houston, Texas, USA.
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Moreno SP, Fusté JM, Kaiser M, Li JSZ, Nassour J, Haggblom C, Denchi EL, Karlseder J. TZAP overexpression induces telomere dysfunction and ALT-like activity in ATRX/DAXX-deficient cells. iScience 2023; 26:106405. [PMID: 37013192 PMCID: PMC10066556 DOI: 10.1016/j.isci.2023.106405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2022] [Revised: 11/13/2022] [Accepted: 03/10/2023] [Indexed: 03/14/2023] Open
Abstract
The appropriate regulation of telomere length homeostasis is crucial for the maintenance of genome integrity. The telomere-binding protein TZAP has been suggested to regulate telomere length by promoting t-circle and c-circle excisions through telomere trimming, yet the molecular mechanisms by which TZAP functions at telomeres are not understood. Using a system based on TZAP overexpression, we show that efficient TZAP recruitment to telomeres occurs in the context of open telomeric chromatin caused by loss of ATRX/DAXX independently of H3.3 deposition. Moreover, our data indicate that TZAP binding to telomeres induces telomere dysfunction and ALT-like activity, resulting in the generation of t-circles and c-circles in a Bloom-Topoisomerase IIIα-RMI1-RMI2 (BTR)-dependent manner.
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Affiliation(s)
- Sara Priego Moreno
- The Salk Institute for Biological Studies, Molecular and Cell Biology Department, 10010 N. Torrey pines Road, La Jolla, CA 92037, USA
| | - Javier Miralles Fusté
- The Salk Institute for Biological Studies, Molecular and Cell Biology Department, 10010 N. Torrey pines Road, La Jolla, CA 92037, USA
| | - Melanie Kaiser
- The Salk Institute for Biological Studies, Molecular and Cell Biology Department, 10010 N. Torrey pines Road, La Jolla, CA 92037, USA
| | - Julia Su Zhou Li
- The Ludwig Institute for Cancer Research, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Joe Nassour
- The Salk Institute for Biological Studies, Molecular and Cell Biology Department, 10010 N. Torrey pines Road, La Jolla, CA 92037, USA
| | - Candy Haggblom
- The Salk Institute for Biological Studies, Molecular and Cell Biology Department, 10010 N. Torrey pines Road, La Jolla, CA 92037, USA
| | - Eros Lazzerini Denchi
- Laboratory for Genome Integrity, National Cancer Institute, Building 37, Room 2144B, Bethesda, MD 20892, USA
| | - Jan Karlseder
- The Salk Institute for Biological Studies, Molecular and Cell Biology Department, 10010 N. Torrey pines Road, La Jolla, CA 92037, USA
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7
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Jones CY, Williams CL, Moreno SP, Morris DK, Mondello C, Karlseder J, Bertuch AA. Hyperextended telomeres promote C-circle formation in telomerase positive human cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023. [PMID: 36747763 PMCID: PMC9900909 DOI: 10.1101/2023.01.26.525615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Telomere length maintenance is crucial to cancer cell immortality. Up to 15% of cancers utilize a telomerase-independent, recombination-based mechanism termed alternative lengthening of telomeres (ALT). The primary ALT biomarker is the C-circle, a type of circular DNA with extrachromosomal telomere repeats (cECTRs). How C-circles form is not well characterized. To investigate C-circle formation in telomerase+ cells, we studied the human cen3tel cell line, in which telomeres progressively hyper-elongated post TERT -immortalization. cECTR signal was observed in 2D gels and C-circle assays but not t-circle assays, which also detect cECTRs. Telomerase activity and C-circle signal were not separable in the analysis of clonal populations, consistent with C-circle production occurring within telomerase+ cells. Two other long telomere, telomerase+ (LTT+) cell lines, HeLa1.3 (~23 kb telomeres) and HeLaE1 (~50 kb telomeres), had similar cECTR properties. Telomerase activity did not directly impact C-circle signal in LTT+ cells; instead, C-circle signal correlated with telomere length. LTT+ lines were less sensitive to hydroxyurea than an ALT+ cell line, suggesting that ALT status is a stronger contributor to replication stress levels than telomere length. Additionally, FANCM did not suppress C-circles in LTT+ cells as it does in ALT+ cells. Thus, C-circle formation may be driven by telomere length, independently of telomerase and replication stress, highlighting limitations of C-circles as a stand-alone ALT biomarker.
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8
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Clinical Characteristics of TZAP (ZBTB48) in Hepatocellular Carcinomas from Tissue, Cell Line, and TCGA. Medicina (B Aires) 2022; 58:medicina58121778. [PMID: 36556980 PMCID: PMC9783728 DOI: 10.3390/medicina58121778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2022] [Revised: 11/24/2022] [Accepted: 11/28/2022] [Indexed: 12/11/2022] Open
Abstract
Background and Objectives: ZBTB48 is a telomere-related protein that has been renamed telomeric zinc finger-associated protein (TZAP). It favorably binds to elongated telomeres to regulate their appropriate length. However, TZAP expression has not been investigated in hepatocellular carcinomas (HCC). Materials and Methods: The clinical significance of TZAP expression in 72 HCC was investigated. Additionally, its findings were supported by open big data and cancer cell lines. Results: TZAP expression level was not associated with the clinical parameters of HCC. TZAP expression induced a poorer survival result (overall survival, p = 0.020; disease-free survival, p = 0.012). TCGA data showed TZAP expression was more frequently found in HCCs with hepatitis C infection (p = 0.023). However, TCGA data revealed that TZAP expression did not predict HCC prognosis. In a cell line study, TZAP inhibition via siRNA suppressed PLC/PRF/5 cell growth; however, cell viability was increased in HepG2 cells. Conclusions: We presented the clinical and prognostic values of TZAP expression in HCC tissues and cancer cell lines. Additionally, the TCGA results also revealed a significant role for TZAP expression. TZAP expression may involve HCC progression and its prognosis.
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Extrachromosomal circular DNA: biogenesis, structure, functions and diseases. Signal Transduct Target Ther 2022; 7:342. [PMID: 36184613 PMCID: PMC9527254 DOI: 10.1038/s41392-022-01176-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 08/14/2022] [Accepted: 09/01/2022] [Indexed: 11/08/2022] Open
Abstract
Extrachromosomal circular DNA (eccDNA), ranging in size from tens to millions of base pairs, is independent of conventional chromosomes. Recently, eccDNAs have been considered an unanticipated major source of somatic rearrangements, contributing to genomic remodeling through chimeric circularization and reintegration of circular DNA into the linear genome. In addition, the origin of eccDNA is considered to be associated with essential chromatin-related events, including the formation of super-enhancers and DNA repair machineries. Moreover, our understanding of the properties and functions of eccDNA has continuously and greatly expanded. Emerging investigations demonstrate that eccDNAs serve as multifunctional molecules in various organisms during diversified biological processes, such as epigenetic remodeling, telomere trimming, and the regulation of canonical signaling pathways. Importantly, its special distribution potentiates eccDNA as a measurable biomarker in many diseases, especially cancers. The loss of eccDNA homeostasis facilitates tumor initiation, malignant progression, and heterogeneous evolution in many cancers. An in-depth understanding of eccDNA provides novel insights for precision cancer treatment. In this review, we summarized the discovery history of eccDNA, discussed the biogenesis, characteristics, and functions of eccDNA. Moreover, we emphasized the role of eccDNA during tumor pathogenesis and malignant evolution. Therapeutically, we summarized potential clinical applications that target aberrant eccDNA in multiple diseases.
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Peng H, Mirouze M, Bucher E. Extrachromosomal circular DNA: A neglected nucleic acid molecule in plants. CURRENT OPINION IN PLANT BIOLOGY 2022; 69:102263. [PMID: 35872391 DOI: 10.1016/j.pbi.2022.102263] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 06/15/2022] [Accepted: 06/19/2022] [Indexed: 06/15/2023]
Abstract
Throughout the years, most plant genomic studies were focused on nuclear chromosomes. Extrachromosomal circular DNA (eccDNA) has largely been neglected for decades since its discovery in 1965. While initial research showed that eccDNAs can originate from highly repetitive sequences, recent findings show that many regions of the genome can contribute to the eccDNA pool. Currently, the biological functions of eccDNAs, if any, are a mystery but recent studies have indicated that they can be regulated by different genomic loci and contribute to stress response and adaptation. In this review, we outline current relevant technological developments facilitating eccDNA identification and the latest discoveries about eccDNAs in plants. Finally, we explore the probable functions and future research directions that could be undertaken with respect to different eccDNA sources.
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Affiliation(s)
- Haoran Peng
- Crop Genome Dynamics Group, Agroscope Changins, 1260, Nyon, Switzerland; Department of Botany and Plant Biology, Section of Biology, Faculty of Science, University of Geneva, 1211, Geneva, Switzerland
| | - Marie Mirouze
- Institut de Recherche pour le Développement (IRD), EMR269 MANGO, Université de Perpignan, 66860 Perpignan, France; Laboratory of Plant Genome and Development, Université de Perpignan, 66860, Perpignan, France.
| | - Etienne Bucher
- Crop Genome Dynamics Group, Agroscope Changins, 1260, Nyon, Switzerland.
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Meeser A, Bartenhagen C, Werr L, Hellmann AM, Kahlert Y, Hemstedt N, Nürnberg P, Altmüller J, Ackermann S, Hero B, Simon T, Peifer M, Fischer M, Rosswog C. Reliable assessment of telomere maintenance mechanisms in neuroblastoma. Cell Biosci 2022; 12:160. [PMID: 36153564 PMCID: PMC9508734 DOI: 10.1186/s13578-022-00896-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2022] [Accepted: 09/03/2022] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND Telomere maintenance mechanisms (TMM) are a hallmark of high-risk neuroblastoma, and are conferred by activation of telomerase or alternative lengthening of telomeres (ALT). However, detection of TMM is not yet part of the clinical routine, and consensus on TMM detection, especially on ALT assessment, remains to be achieved. METHODS Whole genome sequencing (WGS) data of 68 primary neuroblastoma samples were analyzed. Telomere length was calculated from WGS data or by telomere restriction fragment analysis (n = 39). ALT was assessed by C-circle assay (CCA, n = 67) and detection of ALT-associated PML nuclear bodies (APB) by combined fluorescence in situ hybridization and immunofluorescence staining (n = 68). RNA sequencing was performed (n = 64) to determine expression of TERT and telomeric long non-coding RNA (TERRA). Telomerase activity was examined by telomerase repeat amplification protocol (TRAP, n = 15). RESULTS Tumors were considered as telomerase-positive if they harbored a TERT rearrangement, MYCN amplification or high TERT expression (45.6%, 31/68), and ALT-positive if they were positive for APB and CCA (19.1%, 13/68). If all these markers were absent, tumors were considered TMM-negative (25.0%, 17/68). According to these criteria, the majority of samples were classified unambiguously (89.7%, 61/68). Assessment of additional ALT-associated parameters clarified the TMM status of the remaining seven cases with high likelihood: ALT-positive tumors had higher TERRA expression, longer telomeres, more telomere insertions, a characteristic pattern of telomere variant repeats, and were associated with ATRX mutations. CONCLUSIONS We here propose a workflow to reliably detect TMM in neuroblastoma. We show that unambiguous classification is feasible following a stepwise approach that determines both, activation of telomerase and ALT. The workflow proposed in this study can be used in clinical routine and provides a framework to systematically and reliably determine telomere maintenance mechanisms for risk stratification and treatment allocation of neuroblastoma patients.
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Affiliation(s)
- Alina Meeser
- Department of Experimental Pediatric Oncology, University Children's Hospital of Cologne, Kerpener Str. 62, 50937, Cologne, Germany
- Center for Molecular Medicine Cologne, Medical Faculty, University of Cologne, Cologne, Germany
| | - Christoph Bartenhagen
- Department of Experimental Pediatric Oncology, University Children's Hospital of Cologne, Kerpener Str. 62, 50937, Cologne, Germany
- Center for Molecular Medicine Cologne, Medical Faculty, University of Cologne, Cologne, Germany
| | - Lisa Werr
- Department of Experimental Pediatric Oncology, University Children's Hospital of Cologne, Kerpener Str. 62, 50937, Cologne, Germany
- Center for Molecular Medicine Cologne, Medical Faculty, University of Cologne, Cologne, Germany
| | - Anna-Maria Hellmann
- Department of Experimental Pediatric Oncology, University Children's Hospital of Cologne, Kerpener Str. 62, 50937, Cologne, Germany
- Center for Molecular Medicine Cologne, Medical Faculty, University of Cologne, Cologne, Germany
| | - Yvonne Kahlert
- Department of Experimental Pediatric Oncology, University Children's Hospital of Cologne, Kerpener Str. 62, 50937, Cologne, Germany
- Center for Molecular Medicine Cologne, Medical Faculty, University of Cologne, Cologne, Germany
| | - Nadine Hemstedt
- Department of Experimental Pediatric Oncology, University Children's Hospital of Cologne, Kerpener Str. 62, 50937, Cologne, Germany
- Center for Molecular Medicine Cologne, Medical Faculty, University of Cologne, Cologne, Germany
| | - Peter Nürnberg
- Center for Molecular Medicine Cologne, Medical Faculty, University of Cologne, Cologne, Germany
- Cologne Center for Genomics (CCG), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - Janine Altmüller
- Cologne Center for Genomics (CCG), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
- Core Facility Genomics, Berlin Institute of Health at Charité - Universitätsmedizin Berlin, Berlin, Germany
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany
| | - Sandra Ackermann
- Department of Experimental Pediatric Oncology, University Children's Hospital of Cologne, Kerpener Str. 62, 50937, Cologne, Germany
- Center for Molecular Medicine Cologne, Medical Faculty, University of Cologne, Cologne, Germany
| | - Barbara Hero
- Department of Pediatric Oncology and Hematology, University of Cologne, Cologne, Germany
| | - Thorsten Simon
- Department of Pediatric Oncology and Hematology, University of Cologne, Cologne, Germany
| | - Martin Peifer
- Center for Molecular Medicine Cologne, Medical Faculty, University of Cologne, Cologne, Germany
- Department of Translational Genomics, Center of Integrated Oncology Cologne-Bonn, Medical Faculty, University of Cologne, Cologne, Germany
| | - Matthias Fischer
- Department of Experimental Pediatric Oncology, University Children's Hospital of Cologne, Kerpener Str. 62, 50937, Cologne, Germany.
- Center for Molecular Medicine Cologne, Medical Faculty, University of Cologne, Cologne, Germany.
| | - Carolina Rosswog
- Department of Experimental Pediatric Oncology, University Children's Hospital of Cologne, Kerpener Str. 62, 50937, Cologne, Germany.
- Center for Molecular Medicine Cologne, Medical Faculty, University of Cologne, Cologne, Germany.
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12
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Telomeres and Their Neighbors. Genes (Basel) 2022; 13:genes13091663. [PMID: 36140830 PMCID: PMC9498494 DOI: 10.3390/genes13091663] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 09/08/2022] [Accepted: 09/09/2022] [Indexed: 11/21/2022] Open
Abstract
Telomeres are essential structures formed from satellite DNA repeats at the ends of chromosomes in most eukaryotes. Satellite DNA repeat sequences are useful markers for karyotyping, but have a more enigmatic role in the eukaryotic cell. Much work has been done to investigate the structure and arrangement of repetitive DNA elements in classical models with implications for species evolution. Still more is needed until there is a complete picture of the biological function of DNA satellite sequences, particularly when considering non-model organisms. Celebrating Gregor Mendel’s anniversary by going to the roots, this review is designed to inspire and aid new research into telomeres and satellites with a particular focus on non-model organisms and accessible experimental and in silico methods that do not require specialized equipment or expensive materials. We describe how to identify telomere (and satellite) repeats giving many examples of published (and some unpublished) data from these techniques to illustrate the principles behind the experiments. We also present advice on how to perform and analyse such experiments, including details of common pitfalls. Our examples are a selection of recent developments and underexplored areas of research from the past. As a nod to Mendel’s early work, we use many examples from plants and insects, especially as much recent work has expanded beyond the human and yeast models traditional in telomere research. We give a general introduction to the accepted knowledge of telomere and satellite systems and include references to specialized reviews for the interested reader.
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13
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Pan L, Tormey D, Bobon N, Baumann P. Rap1 prevents fusions between long telomeres in fission yeast. EMBO J 2022; 41:e110458. [PMID: 36059259 PMCID: PMC9574727 DOI: 10.15252/embj.2021110458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 08/04/2022] [Accepted: 08/08/2022] [Indexed: 11/15/2022] Open
Abstract
The conserved Rap1 protein is part of the shelterin complex that plays critical roles in chromosome end protection and telomere length regulation. Previous studies have addressed how fission yeast Rap1 contributes to telomere length maintenance, but the mechanism by which the protein inhibits end fusions has remained elusive. Here, we use a mutagenesis screen in combination with high‐throughput sequencing to identify several amino acid positions in Rap1 that have key roles in end protection. Interestingly, mutations at these sites render cells susceptible to genome instability in a conditional manner, whereby longer telomeres are prone to undergoing end fusions, while telomeres within the normal length range are sufficiently protected. The protection of long telomeres is in part dependent on their nuclear envelope attachment mediated by the Rap1–Bqt4 interaction. Our data demonstrate that long telomeres represent a challenge for the maintenance of genome integrity, thereby providing an explanation for species‐specific upper limits on telomere length.
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Affiliation(s)
- Lili Pan
- Department of Biology, Johannes Gutenberg University, Mainz, Germany
| | - Duncan Tormey
- Stowers Institute for Medical Research, Kansas City, MO, USA
| | - Nadine Bobon
- Department of Biology, Johannes Gutenberg University, Mainz, Germany
| | - Peter Baumann
- Department of Biology, Johannes Gutenberg University, Mainz, Germany.,Institute of Molecular Biology, Mainz, Germany
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14
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Wu B, Yan J, Yang J, Xia Y, Li D, Zhang F, Cao H. Extension of the Life Span by Acarbose: Is It Mediated by the Gut Microbiota? Aging Dis 2022; 13:1005-1014. [PMID: 35855337 PMCID: PMC9286917 DOI: 10.14336/ad.2022.0117] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 01/17/2022] [Indexed: 11/17/2022] Open
Abstract
Acarbose can extend the life span of mice through a process involving the gut microbiota. Several factors affect the life span, including mitochondrial function, cellular senescence, telomere length, immune function, and expression of longevity-related genes. In this review, the effects of acarbose-regulated gut microbiota on the life span-influencing factors have been discussed. In addition, a novel theoretical basis for improving our understanding of the mechanisms by which acarbose extends the life span of mice has been suggested.
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Affiliation(s)
- Baiyun Wu
- Nutritional Department, Affiliated Hospital of Jiangnan University, Wuxi, China.
- School of Medicine, Nantong University, Nantong, China.
| | - Jiai Yan
- Nutritional Department, Affiliated Hospital of Jiangnan University, Wuxi, China.
- Clinical Assessment Center of Functional Food, Affiliated Hospital of Jiangnan University, Wuxi, China.
| | - Ju Yang
- Nutritional Department, Affiliated Hospital of Jiangnan University, Wuxi, China.
- Clinical Assessment Center of Functional Food, Affiliated Hospital of Jiangnan University, Wuxi, China.
| | - Yanping Xia
- Nutritional Department, Affiliated Hospital of Jiangnan University, Wuxi, China.
- Clinical Assessment Center of Functional Food, Affiliated Hospital of Jiangnan University, Wuxi, China.
| | - Dan Li
- Nutritional Department, Affiliated Hospital of Jiangnan University, Wuxi, China.
- Clinical Assessment Center of Functional Food, Affiliated Hospital of Jiangnan University, Wuxi, China.
| | - Feng Zhang
- Nutritional Department, Affiliated Hospital of Jiangnan University, Wuxi, China.
- Clinical Assessment Center of Functional Food, Affiliated Hospital of Jiangnan University, Wuxi, China.
- Correspondence should be addressed to: Dr. Hong Cao, () and Dr. Feng Zhang (), Nutritional Department, Affiliated Hospital of Jiangnan University, Wuxi, China
| | - Hong Cao
- Nutritional Department, Affiliated Hospital of Jiangnan University, Wuxi, China.
- Clinical Assessment Center of Functional Food, Affiliated Hospital of Jiangnan University, Wuxi, China.
- Department of Endocrinology, Affiliated Hospital of Jiangnan University, Wuxi, China.
- Correspondence should be addressed to: Dr. Hong Cao, () and Dr. Feng Zhang (), Nutritional Department, Affiliated Hospital of Jiangnan University, Wuxi, China
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15
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Kim GJ, Lee JH, Chae M, Lee DH. Prognostic Value of Telomeric Zinc Finger-Associated Protein Expression in Adenocarcinoma and Squamous Cell Carcinoma of Lung. MEDICINA (KAUNAS, LITHUANIA) 2021; 57:1223. [PMID: 34833441 PMCID: PMC8621189 DOI: 10.3390/medicina57111223] [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] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 11/03/2021] [Accepted: 11/08/2021] [Indexed: 11/17/2022]
Abstract
Background and Objectives: Telomeric zinc finger-associated protein (TZAP) is a telomere regulation protein, previously known as ZBTB48. It binds preferentially to elongated telomeres, competing with telomeric repeat factors 1 and 2. TZAP expression may be associated with carcinogenesis, however; this study has not yet been performed in lung cancer. In this study, we examined the clinicopathological and prognostic values of TZAP expression in non-small cell lung cancer (NSCLC). Materials and Methods: Data were collected from The Cancer Genome Atlas. The clinical and prognostic values of TZAP for NSCLC were examined in adenocarcinoma (AD) and squamous cell carcinoma (SCC). Results: TZAP expression significantly increased in NSCLC tissues compared with normal tissues. In AD, TZAP expression was lower in patients with higher T stage (p = 0.005), and was associated with lymph node stage in SCC (p = 0.005). Survival analysis showed shorter disease-free survival in AD patients with lower TZAP expression (p = 0.047). TZAP expression did not have other clinical or prognostic value for AD and SCC. Conclusions: TZAP expression is a potential prognostic marker for NSCLC, especially in patients with AD.
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Affiliation(s)
- Gun-Jik Kim
- Department of Thoracic and Cardiovascular Surgery, School of Medicine, Kyungpook National University, 130 Dongdeok-ro, Jung-gu, Daegu 41944, Korea;
| | - Jae-Ho Lee
- Department of Anatomy, Keimyung University School of Medicine, Dageu 42601, Korea;
| | - Mincheol Chae
- Dongsan Medical Center, Department of Thoracic and Cardiovascular Surgery, Keimyung University School of Medicine, Dageu 42601, Korea;
| | - Deok-Heon Lee
- Department of Thoracic and Cardiovascular Surgery, School of Medicine, Kyungpook National University, 130 Dongdeok-ro, Jung-gu, Daegu 41944, Korea;
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16
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Gao K, Zhou Y, Lu Q, Lu J, Su L, Su R, Zhang M, Tian Y, Wu L, Yan X. High-Throughput Human Telomere Length Analysis at the Single-Chromosome Level by FISH Coupled with Nano-Flow Cytometry. Anal Chem 2021; 93:9531-9540. [PMID: 34197088 DOI: 10.1021/acs.analchem.1c01544] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Telomere length (TL) is a highly relevant biomarker for age-associated diseases and cancer, yet its clinical applications have been hindered by the inability of existing methods to rapidly measure the TL distribution and the percentage of chromosomes with critically short telomeres (CSTs, < 3 kb). Herein, we report the development of a high-throughput method to measure TL at the single-chromosome level. Metaphase chromosomes are isolated, hybridized with the Alexa Fluor 488-labeled telomeric peptide nucleic acid probe, and analyzed using a laboratory-built ultrasensitive nano-flow cytometer. The fluorescence intensity of individual chromosomes is converted to TL in kilobases upon external calibration. With an analysis rate of several thousand chromosomes per minute, a statistically robust TL distribution histogram is acquired in minutes, and the percentage of chromosomes with CSTs can be quickly assessed. By analyzing peripheral blood lymphocytes of 158 healthy donors, TL is found to shorten with age at a rate of 64 ± 3 bp/year and the percentage of chromosomes with CSTs increases with age at a rate of 0.32 ± 0.02%/year. Moreover, the data of 28 patients with chronic myeloid leukemia (CML) indicate that telomeres are significantly shorter at the time of diagnosis and the clinical phases of CML are closely associated with TL and the percentage of chromosomes with CSTs. This powerful tool could greatly deepen our understanding of telomere biology and improve the clinical utility of telomere biomarkers.
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Affiliation(s)
- Kaimin Gao
- Department of Chemical Biology, MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, Key Laboratory for Chemical Biology of Fujian Province, Collaborative Innovation Center of Chemistry for Energy Materials, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, PR China
| | - Yingxing Zhou
- Department of Chemical Biology, MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, Key Laboratory for Chemical Biology of Fujian Province, Collaborative Innovation Center of Chemistry for Energy Materials, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, PR China
| | - Quanyi Lu
- Department of Hematology, Affiliated Zhongshan Hospital of Xiamen University, Xiamen 361004, PR China
| | - Jingyuan Lu
- Department of Hematology, Affiliated Zhongshan Hospital of Xiamen University, Xiamen 361004, PR China
| | - Liyun Su
- Department of Chemical Biology, MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, Key Laboratory for Chemical Biology of Fujian Province, Collaborative Innovation Center of Chemistry for Energy Materials, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, PR China
| | - Rui Su
- Department of Hematology, The First Affiliated Hospital of Xiamen University, Xiamen 361003, PR China
| | - Miaomiao Zhang
- Department of Chemical Biology, MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, Key Laboratory for Chemical Biology of Fujian Province, Collaborative Innovation Center of Chemistry for Energy Materials, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, PR China
| | - Ye Tian
- Department of Chemical Biology, MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, Key Laboratory for Chemical Biology of Fujian Province, Collaborative Innovation Center of Chemistry for Energy Materials, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, PR China
| | - Lina Wu
- Department of Chemical Biology, MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, Key Laboratory for Chemical Biology of Fujian Province, Collaborative Innovation Center of Chemistry for Energy Materials, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, PR China
| | - Xiaomei Yan
- Department of Chemical Biology, MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, Key Laboratory for Chemical Biology of Fujian Province, Collaborative Innovation Center of Chemistry for Energy Materials, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, PR China
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17
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MacKenzie D, Watters AK, To JT, Young MW, Muratori J, Wilkoff MH, Abraham RG, Plummer MM, Zhang D. ALT Positivity in Human Cancers: Prevalence and Clinical Insights. Cancers (Basel) 2021; 13:2384. [PMID: 34069193 PMCID: PMC8156225 DOI: 10.3390/cancers13102384] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 05/07/2021] [Accepted: 05/11/2021] [Indexed: 02/08/2023] Open
Abstract
Many exciting advances in cancer-related telomere biology have been made in the past decade. Of these recent advances, great progress has also been made with respect to the Alternative Lengthening of Telomeres (ALT) pathway. Along with a better understanding of the molecular mechanism of this unique telomere maintenance pathway, many studies have also evaluated ALT activity in various cancer subtypes. We first briefly review and assess a variety of commonly used ALT biomarkers. Then, we provide both an update on ALT-positive (ALT+) tumor prevalence as well as a systematic clinical assessment of the presently studied ALT+ malignancies. Additionally, we discuss the pathogenetic alterations in ALT+ cancers, for example, the mutation status of ATRX and DAXX, and their correlations with the activation of the ALT pathway. Finally, we highlight important ALT+ clinical associations within each cancer subtype and subdivisions within, as well as their prognoses. We hope this alternative perspective will allow scientists, clinicians, and drug developers to have greater insight into the ALT cancers so that together, we may develop more efficacious treatments and improved management strategies to meet the urgent needs of cancer patients.
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Affiliation(s)
| | | | | | | | | | | | | | - Maria M. Plummer
- Department of Biomedical Sciences, College of Osteopathic Medicine, New York Institute of Technology, Old Westbury, NY 11568, USA; (D.M.J.); (A.K.W.); (J.T.T.); (M.W.Y.); (J.M.); (M.H.W.); (R.G.A.)
| | - Dong Zhang
- Department of Biomedical Sciences, College of Osteopathic Medicine, New York Institute of Technology, Old Westbury, NY 11568, USA; (D.M.J.); (A.K.W.); (J.T.T.); (M.W.Y.); (J.M.); (M.H.W.); (R.G.A.)
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18
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The Power of Stress: The Telo-Hormesis Hypothesis. Cells 2021; 10:cells10051156. [PMID: 34064566 PMCID: PMC8151059 DOI: 10.3390/cells10051156] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 04/29/2021] [Accepted: 05/06/2021] [Indexed: 02/06/2023] Open
Abstract
Adaptative response to stress is a strategy conserved across evolution to promote survival. In this context, the groundbreaking findings of Miroslav Radman on the adaptative value of changing mutation rates opened new avenues in our understanding of stress response. Inspired by this work, we explore here the putative beneficial effects of changing the ends of eukaryotic chromosomes, the telomeres, in response to stress. We first summarize basic principles in telomere biology and then describe how various types of stress can alter telomere structure and functions. Finally, we discuss the hypothesis of stress-induced telomere signaling with hormetic effects.
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19
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Chen L, Roake CM, Galati A, Bavasso F, Micheli E, Saggio I, Schoeftner S, Cacchione S, Gatti M, Artandi SE, Raffa GD. Loss of Human TGS1 Hypermethylase Promotes Increased Telomerase RNA and Telomere Elongation. Cell Rep 2021; 30:1358-1372.e5. [PMID: 32023455 PMCID: PMC7156301 DOI: 10.1016/j.celrep.2020.01.004] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 11/09/2019] [Accepted: 12/31/2019] [Indexed: 02/08/2023] Open
Abstract
Biogenesis of the human telomerase RNA (hTR) involves a complex series of posttranscriptional modifications, including hypermethylation of the 5' mono-methylguanosine cap to a tri-methylguanosine cap (TMG). How the TMG cap affects hTR maturation is unknown. Here, we show that depletion of trimethylguanosine synthase 1 (TGS1), the enzyme responsible for cap hypermethylation, increases levels of hTR and telomerase. Diminished trimethylation increases hTR association with the cap-binding complex (CBC) and with Sm chaperone proteins. Loss of TGS1 causes an increase in accumulation of mature hTR in both the nucleus and the cytoplasm compared with controls. In TGS1 mutant cells, increased hTR assembles with telomerase reverse transcriptase (TERT) protein to yield elevated active telomerase complexes and increased telomerase activity, resulting in telomere elongation in cultured human cells. Our results show that TGS1-mediated hypermethylation of the hTR cap inhibits hTR accumulation, restrains levels of assembled telomerase, and limits telomere elongation.
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Affiliation(s)
- Lu Chen
- Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Caitlin M Roake
- Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Alessandra Galati
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Roma, Italy
| | - Francesca Bavasso
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Roma, Italy
| | - Emanuela Micheli
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Roma, Italy
| | - Isabella Saggio
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Roma, Italy
| | - Stefan Schoeftner
- Cancer Epigenetic Group, Laboratorio Nazionale Consorzio Interuniversitario Biotecnologie, Trieste, Italy
| | - Stefano Cacchione
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Roma, Italy
| | - Maurizio Gatti
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Roma, Italy; Istituto di Biologia e Patologia Molecolari (IBPM) del CNR, Roma, Italy
| | - Steven E Artandi
- Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA.
| | - Grazia D Raffa
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Roma, Italy.
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20
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Wang M, Chen X, Yu F, Ding H, Zhang Y, Wang K. Extrachromosomal Circular DNAs: Origin, formation and emerging function in Cancer. Int J Biol Sci 2021; 17:1010-1025. [PMID: 33867825 PMCID: PMC8040306 DOI: 10.7150/ijbs.54614] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Accepted: 02/05/2021] [Indexed: 02/06/2023] Open
Abstract
The majority of cellular DNAs in eukaryotes are organized into linear chromosomes. In addition to chromosome DNAs, genes also reside on extrachromosomal elements. The extrachromosomal DNAs are commonly found to be circular, and they are referred to as extrachromosomal circular DNAs (eccDNAs). Recent technological advances have enriched our knowledge of eccDNA biology. There is currently increasing concern about the connection between eccDNA and cancer. Gene amplification on eccDNAs is prevalent in cancer. Moreover, eccDNAs commonly harbor oncogenes or drug resistance genes, hence providing a growth or survival advantage to cancer cells. eccDNAs play an important role in tumor heterogeneity and evolution, facilitating tumor adaptation to challenging circumstances. In addition, eccDNAs have recently been identified as cell-free DNAs in circulating system. The altered level of eccDNAs is observed in cancer patients relative to healthy controls. Particularly, eccDNAs are associated with cancer progression and poor outcomes. Thus, eccDNAs could be useful as novel biomarkers for the diagnosis and prognosis of cancer. In this review, we summarize current knowledge regarding the formation, characteristics and biological importance of eccDNAs, with a focus on the molecular mechanisms associated with their roles in cancer progression. We also discuss their potential applications in the detection and treatment of cancer. A better understanding of the functional role of eccDNAs in cancer would facilitate the comprehensive analysis of molecular mechanisms involved in cancer pathogenesis.
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Affiliation(s)
- Man Wang
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, College of Medicine, Qingdao University, Qingdao 266021, China
| | - Xinzhe Chen
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, College of Medicine, Qingdao University, Qingdao 266021, China
| | - Fei Yu
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, College of Medicine, Qingdao University, Qingdao 266021, China
| | - Han Ding
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, College of Medicine, Qingdao University, Qingdao 266021, China
| | - Yuan Zhang
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, College of Medicine, Qingdao University, Qingdao 266021, China
| | - Kun Wang
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, College of Medicine, Qingdao University, Qingdao 266021, China
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21
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Wood ML, Veal CD, Neumann R, Suárez NM, Nichols J, Parker AJ, Martin D, Romaine SPR, Codd V, Samani NJ, Voors AA, Tomaszewski M, Flamand L, Davison AJ, Royle NJ. Variation in human herpesvirus 6B telomeric integration, excision, and transmission between tissues and individuals. eLife 2021; 10:70452. [PMID: 34545807 PMCID: PMC8492063 DOI: 10.7554/elife.70452] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Accepted: 09/20/2021] [Indexed: 12/12/2022] Open
Abstract
Human herpesviruses 6A and 6B (HHV-6A/6B) are ubiquitous pathogens that persist lifelong in latent form and can cause severe conditions upon reactivation. They are spread by community-acquired infection of free virus (acqHHV6A/6B) and by germline transmission of inherited chromosomally integrated HHV-6A/6B (iciHHV-6A/6B) in telomeres. We exploited a hypervariable region of the HHV-6B genome to investigate the relationship between acquired and inherited virus and revealed predominantly maternal transmission of acqHHV-6B in families. Remarkably, we demonstrate that some copies of acqHHV-6B in saliva from healthy adults gained a telomere, indicative of integration and latency, and that the frequency of viral genome excision from telomeres in iciHHV-6B carriers is surprisingly high and varies between tissues. In addition, newly formed short telomeres generated by partial viral genome release are frequently lengthened, particularly in telomerase-expressing pluripotent cells. Consequently, iciHHV-6B carriers are mosaic for different iciHHV-6B structures, including circular extra-chromosomal forms that have the potential to reactivate. Finally, we show transmission of an HHV-6B strain from an iciHHV-6B mother to her non-iciHHV-6B son. Altogether, we demonstrate that iciHHV-6B can readily transition between telomere-integrated and free virus forms.
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Affiliation(s)
- Michael L Wood
- Department of Genetics and Genome Biology, University of LeicesterLeicesterUnited Kingdom
| | - Colin D Veal
- Department of Genetics and Genome Biology, University of LeicesterLeicesterUnited Kingdom
| | - Rita Neumann
- Department of Genetics and Genome Biology, University of LeicesterLeicesterUnited Kingdom
| | - Nicolás M Suárez
- MRC-University of Glasgow Centre for Virus ResearchGlasgowUnited Kingdom
| | - Jenna Nichols
- MRC-University of Glasgow Centre for Virus ResearchGlasgowUnited Kingdom
| | - Andrei J Parker
- Department of Genetics and Genome Biology, University of LeicesterLeicesterUnited Kingdom
| | - Diana Martin
- Department of Genetics and Genome Biology, University of LeicesterLeicesterUnited Kingdom
| | - Simon PR Romaine
- Department of Cardiovascular Sciences, University of LeicesterLeicesterUnited Kingdom,NIHR Leicester Biomedical Research Centre, Glenfield HospitalLeicesterUnited Kingdom
| | - Veryan Codd
- Department of Cardiovascular Sciences, University of LeicesterLeicesterUnited Kingdom
| | - Nilesh J Samani
- Department of Cardiovascular Sciences, University of LeicesterLeicesterUnited Kingdom
| | - Adriaan A Voors
- University of Groningen, Department of Cardiology, University Medical Center GroningenGroningenNetherlands
| | - Maciej Tomaszewski
- Division of Cardiovascular Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of ManchesterManchesterUnited Kingdom
| | - Louis Flamand
- Department of Microbiology, Infectious Diseases and Immunology, Faculty of Medicine, Université Laval, Quebec CityQuébecCanada
| | - Andrew J Davison
- MRC-University of Glasgow Centre for Virus ResearchGlasgowUnited Kingdom
| | - Nicola J Royle
- Department of Genetics and Genome Biology, University of LeicesterLeicesterUnited Kingdom
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22
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Jung SJ, Seo YR, Park WJ, Heo YR, Lee YH, Kim S, Lee JH. Clinicopathological Characteristics of TZAP Expression in Colorectal Cancers. Onco Targets Ther 2020; 13:12933-12942. [PMID: 33364783 PMCID: PMC7751716 DOI: 10.2147/ott.s274394] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 11/26/2020] [Indexed: 12/26/2022] Open
Abstract
Purpose The zinc finger protein, ZBTB48, is a telomere-associated protein. It was renamed as telomeric zinc finger-associated protein (TZAP) binding to elongated telomeres. However, its expression level was not measured in cancers. Patients and Methods We analyzed TZAP mRNA levels in 60 colorectal cancers (CRC) and its correlation with telomere length and TERT was studied. Results TZAP mRNA in CRC was higher statistically than that in paired non-cancerous tissues (p = 0.033). Higher TZAP was found in carcinoembryonic antigen (CEA)-positive CRCs (>5 ng/mL) (p = 0.012). Shorter telomere was found in CRCs with high TZAP expression than that with low TZAP expression (p = 0.010). According to quantitative correlation analysis, TZAP has a correlation with age (r = −0.349, p = 0.007), TERT (r = 0.279, p = 0.041) and telomere length (r = −0.305, p = 0.021). TZAP expression did not harbor prognostic value in CRC. Inhibition of TZAP expression by siRNA suppresses cell growth in HT29 cells; however, it resulted in increased cell viability in HCT116 cells. TZAP inhibition induces a decrease in mRNA levels of TERT in both HT29 and HCT116 cells. TCGA data analysis showed higher expression of TZAP showed poorer overall survival in colon cancer (p = 0.001); however, it did not have a significance in rectal cancer (p = 0.951). Conclusion We suggested that TZAP may be a possible biomarker for CRC.
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Affiliation(s)
- Soo-Jung Jung
- Department of Anatomy, Keimyung University School of Medicine, Daegu, South Korea
| | - Yu-Ri Seo
- Department of Molecular Medicine, School of Medicine, Keimyung University, Daegu, South Korea
| | - Won-Jin Park
- Department of Anatomy, Keimyung University School of Medicine, Daegu, South Korea
| | - Yu-Ran Heo
- Department of Anatomy, Keimyung University School of Medicine, Daegu, South Korea
| | - Yun-Han Lee
- Department of Molecular Medicine, School of Medicine, Keimyung University, Daegu, South Korea
| | - Shin Kim
- Department of Immunology, School of Medicine, Keimyung University, Daegu, South Korea
| | - Jae-Ho Lee
- Department of Anatomy, Keimyung University School of Medicine, Daegu, South Korea
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23
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Mazzucco G, Huda A, Galli M, Piccini D, Giannattasio M, Pessina F, Doksani Y. Telomere damage induces internal loops that generate telomeric circles. Nat Commun 2020; 11:5297. [PMID: 33082350 PMCID: PMC7576219 DOI: 10.1038/s41467-020-19139-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 09/28/2020] [Indexed: 12/21/2022] Open
Abstract
Extrachromosomal telomeric circles are commonly invoked as important players in telomere maintenance, but their origin has remained elusive. Using electron microscopy analysis on purified telomeres we show that, apart from known structures, telomeric repeats accumulate internal loops (i-loops) that occur in the proximity of nicks and single-stranded DNA gaps. I-loops are induced by single-stranded damage at normal telomeres and represent the majority of telomeric structures detected in ALT (Alternative Lengthening of Telomeres) tumor cells. Our data indicate that i-loops form as a consequence of the exposure of single-stranded DNA at telomeric repeats. Finally, we show that these damage-induced i-loops can be excised to generate extrachromosomal telomeric circles resulting in loss of telomeric repeats. Our results identify damage-induced i-loops as a new intermediate in telomere metabolism and reveal a simple mechanism that links telomere damage to the accumulation of extrachromosomal telomeric circles and to telomere erosion.
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Affiliation(s)
- Giulia Mazzucco
- IFOM, the FIRC Institute of Molecular Oncology, via Adamello 16, 20139, Milan, Italy
| | - Armela Huda
- IFOM, the FIRC Institute of Molecular Oncology, via Adamello 16, 20139, Milan, Italy
| | - Martina Galli
- IFOM, the FIRC Institute of Molecular Oncology, via Adamello 16, 20139, Milan, Italy
| | - Daniele Piccini
- IFOM, the FIRC Institute of Molecular Oncology, via Adamello 16, 20139, Milan, Italy
| | - Michele Giannattasio
- IFOM, the FIRC Institute of Molecular Oncology, via Adamello 16, 20139, Milan, Italy.,Dipartimento di Oncologia ed Emato-Oncologia, Università degli Studi di Milano, Via Festa del Perdono 7, Milan, 20122, Italy
| | - Fabio Pessina
- IFOM, the FIRC Institute of Molecular Oncology, via Adamello 16, 20139, Milan, Italy
| | - Ylli Doksani
- IFOM, the FIRC Institute of Molecular Oncology, via Adamello 16, 20139, Milan, Italy.
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24
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Awad A, Glousker G, Lamm N, Tawil S, Hourvitz N, Smoom R, Revy P, Tzfati Y. Full length RTEL1 is required for the elongation of the single-stranded telomeric overhang by telomerase. Nucleic Acids Res 2020; 48:7239-7251. [PMID: 32542379 PMCID: PMC7367169 DOI: 10.1093/nar/gkaa503] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2019] [Revised: 05/29/2020] [Accepted: 06/02/2020] [Indexed: 12/17/2022] Open
Abstract
Telomeres cap the ends of eukaryotic chromosomes and distinguish them from broken DNA ends to suppress DNA damage response, cell cycle arrest and genomic instability. Telomeres are elongated by telomerase to compensate for incomplete replication and nuclease degradation and to extend the proliferation potential of germ and stem cells and most cancers. However, telomeres in somatic cells gradually shorten with age, ultimately leading to cellular senescence. Hoyeraal-Hreidarsson syndrome (HHS) is characterized by accelerated telomere shortening and diverse symptoms including bone marrow failure, immunodeficiency, and neurodevelopmental defects. HHS is caused by germline mutations in telomerase subunits, factors essential for its biogenesis and recruitment to telomeres, and in the helicase RTEL1. While diverse phenotypes were associated with RTEL1 deficiency, the telomeric role of RTEL1 affected in HHS is yet unknown. Inducible ectopic expression of wild-type RTEL1 in patient fibroblasts rescued the cells, enabled telomerase-dependent telomere elongation and suppressed the abnormal cellular phenotypes, while silencing its expression resulted in gradual telomere shortening. Our observations reveal an essential role of the RTEL1 C-terminus in facilitating telomerase action at the telomeric 3′ overhang. Thus, the common etiology for HHS is the compromised telomerase action, resulting in telomere shortening and reduced lifespan of telomerase positive cells.
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Affiliation(s)
- Aya Awad
- Department of Genetics, The Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Givat Ram, Jerusalem 91904, Israel
| | - Galina Glousker
- Department of Genetics, The Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Givat Ram, Jerusalem 91904, Israel
| | - Noa Lamm
- Department of Genetics, The Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Givat Ram, Jerusalem 91904, Israel
| | - Shadi Tawil
- Department of Genetics, The Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Givat Ram, Jerusalem 91904, Israel
| | - Noa Hourvitz
- Department of Genetics, The Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Givat Ram, Jerusalem 91904, Israel
| | - Riham Smoom
- Department of Genetics, The Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Givat Ram, Jerusalem 91904, Israel
| | - Patrick Revy
- INSERM UMR 1163, Laboratory of Genome Dynamics in the Immune System, Equipe Labellisée Ligue contre le Cancer and Paris Descartes-Sorbonne Paris Cité University, Imagine Institute, Paris, France
| | - Yehuda Tzfati
- Department of Genetics, The Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Givat Ram, Jerusalem 91904, Israel
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25
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Yan Y, Guo G, Huang J, Gao M, Zhu Q, Zeng S, Gong Z, Xu Z. Current understanding of extrachromosomal circular DNA in cancer pathogenesis and therapeutic resistance. J Hematol Oncol 2020; 13:124. [PMID: 32928268 PMCID: PMC7491193 DOI: 10.1186/s13045-020-00960-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 09/03/2020] [Indexed: 02/08/2023] Open
Abstract
Extrachromosomal circular DNA was recently found to be particularly abundant in multiple human cancer cells, although its frequency varies among different tumor types. Elevated levels of extrachromosomal circular DNA have been considered an effective biomarker of cancer pathogenesis. Multiple reports have demonstrated that the amplification of oncogenes and therapeutic resistance genes located on extrachromosomal DNA is a frequent event that drives intratumoral genetic heterogeneity and provides a potential evolutionary advantage. This review highlights the current understanding of the extrachromosomal circular DNA present in the tissues and circulation of patients with advanced cancers and provides a detailed discussion of their substantial roles in tumor regulation. Confirming the presence of cancer-related extrachromosomal circular DNA would provide a putative testing strategy for the precision diagnosis and treatment of human malignancies in clinical practice.
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Affiliation(s)
- Yuanliang Yan
- Department of Pharmacy, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China.,Department of Oncology, Mayo Clinic, Rochester, MN, 55905, USA
| | - Guijie Guo
- Department of Oncology, Mayo Clinic, Rochester, MN, 55905, USA
| | - Jinzhou Huang
- Department of Oncology, Mayo Clinic, Rochester, MN, 55905, USA
| | - Ming Gao
- Department of Oncology, Mayo Clinic, Rochester, MN, 55905, USA
| | - Qian Zhu
- Department of Oncology, Mayo Clinic, Rochester, MN, 55905, USA
| | - Shuangshuang Zeng
- Department of Pharmacy, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China
| | - Zhicheng Gong
- Department of Pharmacy, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China
| | - Zhijie Xu
- Department of Pathology, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China. .,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China.
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26
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Sung JY, Lim HW, Joung JG, Park WY. Pan-Cancer Analysis of Alternative Lengthening of Telomere Activity. Cancers (Basel) 2020; 12:cancers12082207. [PMID: 32784588 PMCID: PMC7465155 DOI: 10.3390/cancers12082207] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 08/01/2020] [Accepted: 08/05/2020] [Indexed: 02/06/2023] Open
Abstract
Alternative lengthening of telomeres (ALT) is a telomerase-independent mechanism that extends telomeres in cancer cells. It influences tumorigenesis and patient survival. Despite the clinical significance of ALT in tumors, the manner in which ALT is activated and influences prognostic outcomes in distinct cancer types is unclear. In this work, we profiled distinct telomere maintenance mechanisms (TMMs) using 8953 transcriptomes of 31 different cancer types from The Cancer Genome Atlas (TCGA). Our results demonstrated that approximately 29% of cancer types display high ALT activity with low telomerase activity in the telomere-lengthening group. Among the distinct ALT mechanisms, homologous recombination was frequently observed in sarcoma, adrenocortical carcinoma, and kidney chromophobe. Five cancer types showed a significant difference in survival in the presence of high ALT activity. Sarcoma patients with elevated ALT had unfavorable risks (p < 0.038) coupled with a high expression of TOP2A, suggesting this as a potential drug target. On the contrary, glioblastoma patients had favorable risks (p < 0.02), and showed low levels of antigen-presenting cells. Together, our analyses highlight cancer type-dependent TMM activities and ALT-associated genes as potential therapeutic targets.
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Affiliation(s)
- Ji-Yong Sung
- Samsung Genome Institute, Samsung Medical Center, Seoul 06351, Korea;
- Department of Health Science and Technology, Samsung Advanced Institute of Health Science and Technology, Sungkyunkwan University, Seoul 06351, Korea
| | - Hee-Woong Lim
- Division of Biomedical Informatics, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229, USA;
| | - Je-Gun Joung
- Samsung Genome Institute, Samsung Medical Center, Seoul 06351, Korea;
- Correspondence: (J.-G.J.); (W.-Y.P.); Tel.: +82-2-3410-1706 (J.-G.J.); +82-2-3410-6128 (W.-Y.P.); Fax: +82-2-2148-9819 (W.-Y.P.)
| | - Woong-Yang Park
- Samsung Genome Institute, Samsung Medical Center, Seoul 06351, Korea;
- Department of Health Science and Technology, Samsung Advanced Institute of Health Science and Technology, Sungkyunkwan University, Seoul 06351, Korea
- Department of Molecular Cell Biology, School of Medicine, Sungkyunkwan University, Seoul 06351, Korea
- Correspondence: (J.-G.J.); (W.-Y.P.); Tel.: +82-2-3410-1706 (J.-G.J.); +82-2-3410-6128 (W.-Y.P.); Fax: +82-2-2148-9819 (W.-Y.P.)
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27
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Kahl VFS, Allen JAM, Nelson CB, Sobinoff AP, Lee M, Kilo T, Vasireddy RS, Pickett HA. Telomere Length Measurement by Molecular Combing. Front Cell Dev Biol 2020; 8:493. [PMID: 32612998 PMCID: PMC7308456 DOI: 10.3389/fcell.2020.00493] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 05/25/2020] [Indexed: 12/14/2022] Open
Abstract
Telomeres are repetitive regions of DNA bound by specialized proteins at the termini of linear chromosomes that prevent the natural chromosome ends from being recognized as DNA double strand breaks. Telomeric DNA is gradually eroded with each round of cell division, resulting in the accumulation of critically short or dysfunctional telomeres that eventually trigger cellular senescence. Consequently, telomere length is indicative of the proliferative capacity of a cell. Multiple methods exist to measure telomere length and telomere content, but a simple and reliable technique to accurately measure individual telomere lengths is currently lacking. We have developed the Telomere length Combing Assay (TCA) to measure telomere length on stretched DNA fibers. We used TCA to measure telomere erosion in primary human fibroblasts, and to detect telomere lengthening in response to activation of telomere maintenance pathways. TCA was also used to accurately measure telomere length in healthy individuals, and to identify critically short telomeres in patients with telomere biology disorders. TCA is performed on isolated DNA, negating the need for cycling cells. TCA is amenable to semi-automated image analysis, and can be fully automated using the Genomic Vision molecular combing platform. This not only precludes sampling bias, but also provides the potential for high-throughput applications and clinical development. TCA is a simple and versatile technique to measure the distribution of individual telomere lengths in a cell population, offering improved accuracy, and more detailed biological insight for telomere length measurement applications.
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Affiliation(s)
- Vivian F S Kahl
- Telomere Length Regulation Unit, Children's Medical Research Institute, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
| | - Joshua A M Allen
- Telomere Length Regulation Unit, Children's Medical Research Institute, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
| | - Christopher B Nelson
- Telomere Length Regulation Unit, Children's Medical Research Institute, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
| | - Alexander P Sobinoff
- Telomere Length Regulation Unit, Children's Medical Research Institute, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
| | - Michael Lee
- Telomere Length Regulation Unit, Children's Medical Research Institute, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
| | - Tatjana Kilo
- Department of Hematology, Children's Hospital at Westmead, Sydney Children's Hospitals Network, Sydney, NSW, Australia
| | - Raja S Vasireddy
- Department of Hematology, Children's Hospital at Westmead, Sydney Children's Hospitals Network, Sydney, NSW, Australia
| | - Hilda A Pickett
- Telomere Length Regulation Unit, Children's Medical Research Institute, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
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28
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Koneru B, Lopez G, Farooqi A, Conkrite KL, Nguyen TH, Macha SJ, Modi A, Rokita JL, Urias E, Hindle A, Davidson H, Mccoy K, Nance J, Yazdani V, Irwin MS, Yang S, Wheeler DA, Maris JM, Diskin SJ, Reynolds CP. Telomere Maintenance Mechanisms Define Clinical Outcome in High-Risk Neuroblastoma. Cancer Res 2020; 80:2663-2675. [PMID: 32291317 PMCID: PMC7313726 DOI: 10.1158/0008-5472.can-19-3068] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 12/05/2019] [Accepted: 04/09/2020] [Indexed: 12/11/2022]
Abstract
Neuroblastoma is a childhood cancer with heterogeneous clinical outcomes. To comprehensively assess the impact of telomere maintenance mechanism (TMM) on clinical outcomes in high-risk neuroblastoma, we integrated the C-circle assay [a marker for alternative lengthening of telomeres (ALT)], TERT mRNA expression by RNA-sequencing, whole-genome/exome sequencing, and clinical covariates in 134 neuroblastoma patient samples at diagnosis. In addition, we assessed TMM in neuroblastoma cell lines (n = 104) and patient-derived xenografts (n = 28). ALT was identified in 23.4% of high-risk neuroblastoma tumors and genomic alterations in ATRX were detected in 60% of ALT tumors; 40% of ALT tumors lacked genomic alterations in known ALT-associated genes. Patients with high-risk neuroblastoma were classified into three subgroups (TERT-high, ALT+, and TERT-low/non-ALT) based on presence of C-circles and TERT mRNA expression (above or below median TERT expression). Event-free survival was similar among TERT-high, ALT+, or TERT-low/non-ALT patients. However, overall survival (OS) for TERT-low/non-ALT patients was significantly higher relative to TERT-high or ALT patients (log-rank test; P < 0.01) independent of current clinical and molecular prognostic markers. Consistent with the observed higher OS in patients with TERT-low/non-ALT tumors, continuous shortening of telomeres and decreasing viability occurred in low TERT-expressing, non-ALT patient-derived high-risk neuroblastoma cell lines. These findings demonstrate that assaying TMM with TERT mRNA expression and C-circles provides precise stratification of high-risk neuroblastoma into three subgroups with substantially different OS: a previously undescribed TERT-low/non-ALT cohort with superior OS (even after relapse) and two cohorts of patients with poor survival that have distinct molecular therapeutic targets. SIGNIFICANCE: These findings assess telomere maintenance mechanisms with TERT mRNA and the ALT DNA biomarker C-circles to stratify neuroblastoma into three groups, with distinct overall survival independent of currently used clinical risk classifiers.
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Affiliation(s)
- Balakrishna Koneru
- Cancer Center and Department of Pediatrics, School of Medicine, Texas Tech University Health Sciences Center School of Medicine, Texas
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Gonzalo Lopez
- Division of Oncology, Children's Hospital of Philadelphia and Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
- Department of Bioinformatics and Health Informatics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Ahsan Farooqi
- Cancer Center and Department of Pediatrics, School of Medicine, Texas Tech University Health Sciences Center School of Medicine, Texas
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Karina L Conkrite
- Division of Oncology, Children's Hospital of Philadelphia and Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
- Department of Bioinformatics and Health Informatics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Thinh H Nguyen
- Cancer Center and Department of Pediatrics, School of Medicine, Texas Tech University Health Sciences Center School of Medicine, Texas
| | - Shawn J Macha
- Cancer Center and Department of Pediatrics, School of Medicine, Texas Tech University Health Sciences Center School of Medicine, Texas
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Apexa Modi
- Division of Oncology, Children's Hospital of Philadelphia and Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
- Department of Bioinformatics and Health Informatics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Jo Lynne Rokita
- Division of Oncology, Children's Hospital of Philadelphia and Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
- Department of Bioinformatics and Health Informatics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
- Center for Data-Driven Discovery in Biomedicine, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Eduardo Urias
- Cancer Center and Department of Pediatrics, School of Medicine, Texas Tech University Health Sciences Center School of Medicine, Texas
| | - Ashly Hindle
- Cancer Center and Department of Pediatrics, School of Medicine, Texas Tech University Health Sciences Center School of Medicine, Texas
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Heather Davidson
- Cancer Center and Department of Pediatrics, School of Medicine, Texas Tech University Health Sciences Center School of Medicine, Texas
| | - Kristyn Mccoy
- Cancer Center and Department of Pediatrics, School of Medicine, Texas Tech University Health Sciences Center School of Medicine, Texas
| | - Jonas Nance
- Cancer Center and Department of Pediatrics, School of Medicine, Texas Tech University Health Sciences Center School of Medicine, Texas
| | - Vanda Yazdani
- Cancer Center and Department of Pediatrics, School of Medicine, Texas Tech University Health Sciences Center School of Medicine, Texas
| | - Meredith S Irwin
- Department of Pediatrics, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Shengping Yang
- Cancer Center and Department of Pediatrics, School of Medicine, Texas Tech University Health Sciences Center School of Medicine, Texas
| | - David A Wheeler
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas
| | - John M Maris
- Division of Oncology, Children's Hospital of Philadelphia and Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Sharon J Diskin
- Division of Oncology, Children's Hospital of Philadelphia and Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
- Department of Bioinformatics and Health Informatics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - C Patrick Reynolds
- Cancer Center and Department of Pediatrics, School of Medicine, Texas Tech University Health Sciences Center School of Medicine, Texas.
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas
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29
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Long-lived post-mitotic cell aging: is a telomere clock at play? Mech Ageing Dev 2020; 189:111256. [PMID: 32380018 DOI: 10.1016/j.mad.2020.111256] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 04/25/2020] [Accepted: 04/27/2020] [Indexed: 12/27/2022]
Abstract
Senescence is a cellular response to stress for both dividing and post-mitotic cells. Noteworthy, long-lived post-mitotic cells (collectively named LLPMCs), which can live for decades in the organism, can exhibit a distinct type of cellular aging characterized by a progressive functional decline not associated to an overt senescence phenotype. The age-related drivers of senescence and aging in LLPMCs remain largely unknown. There is evidence that an increased production of reactive oxygen species (ROS) due to dysfunctional mitochondria, coupled with an inherent inability of cellular-degradation mechanisms to remove damaged molecules, is responsible for senescence and aging in LLPMC. Although telomeric DNA shortening, by nature linked to cell division, is generally not considered as a driver of LLPMC aging and senescence, we discuss recent reports revealing the existence of age-related telomere changes in LLPMC. These findings reveal unexpected roles for telomeres in LLPMC function and invite us to consider the hypothesis of a complex telomere clock involved in both dividing and non-dividing cell aging.
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Clinical and Prognostic Significance of TZAP Expression in Cervical Cancer. ACTA ACUST UNITED AC 2020; 56:medicina56050207. [PMID: 32344888 PMCID: PMC7279327 DOI: 10.3390/medicina56050207] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 04/23/2020] [Accepted: 04/24/2020] [Indexed: 12/11/2022]
Abstract
Background and Objectives: Telomeric zinc finger-associated protein (TZAP) is a telomere-associated factor that was previously called ZBTB48. This protein binds preferentially to long telomeres, competing with telomeric repeat factors 1 and 2. Genetic changes in TZAP may be associated with cancer pathogenesis; however, this relationship has not yet been elucidated for any type of cancer. In this study, we aimed to examine the clinicopathologic and prognostic value of TZAP expression in cervical cancer (CC). Materials and Methods: The data were extracted from The Cancer Genome Atlas cohorts by OncoLnc (21 cancer types, 7700 cancers). The prognostic value of TZAP for different stages of 264 CCs was examined using survival analysis. Results: The TZAP expression did not differ significantly between CC and normal matched tissues. Age, cancer stage, and viral infection were not associated with TZAP expression. Survival analysis revealed a shorter overall survival in CC patients with a lower TZAP expression (χ2 = 3.62, p = 0.057). The prognostic value of TZAP expression was greater in patients with N1 stage CC (χ2 = 5.64, p = 0.018). Conclusion: TZAP expression is a possible prognostic marker for CC, especially stage N1 CC.
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31
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"Mitotic Slippage" and Extranuclear DNA in Cancer Chemoresistance: A Focus on Telomeres. Int J Mol Sci 2020; 21:ijms21082779. [PMID: 32316332 PMCID: PMC7215480 DOI: 10.3390/ijms21082779] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 04/13/2020] [Accepted: 04/14/2020] [Indexed: 02/07/2023] Open
Abstract
Mitotic slippage (MS), the incomplete mitosis that results in a doubled genome in interphase, is a typical response of TP53-mutant tumors resistant to genotoxic therapy. These polyploidized cells display premature senescence and sort the damaged DNA into the cytoplasm. In this study, we explored MS in the MDA-MB-231 cell line treated with doxorubicin (DOX). We found selective release into the cytoplasm of telomere fragments enriched in telomerase reverse transcriptase (hTERT), telomere capping protein TRF2, and DNA double-strand breaks marked by γH2AX, in association with ubiquitin-binding protein SQSTM1/p62. This occurs along with the alternative lengthening of telomeres (ALT) and DNA repair by homologous recombination (HR) in the nuclear promyelocytic leukemia (PML) bodies. The cells in repeated MS cycles activate meiotic genes and display holocentric chromosomes characteristic for inverted meiosis (IM). These giant cells acquire an amoeboid phenotype and finally bud the depolyploidized progeny, restarting the mitotic cycling. We suggest the reversible conversion of the telomerase-driven telomere maintenance into ALT coupled with IM at the sub-telomere breakage sites introduced by meiotic nuclease SPO11. All three MS mechanisms converging at telomeres recapitulate the amoeba-like agamic life-cycle, decreasing the mutagenic load and enabling the recovery of recombined, reduced progeny for return into the mitotic cycle.
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32
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Ain Q, Schmeer C, Wengerodt D, Witte OW, Kretz A. Extrachromosomal Circular DNA: Current Knowledge and Implications for CNS Aging and Neurodegeneration. Int J Mol Sci 2020; 21:ijms21072477. [PMID: 32252492 PMCID: PMC7177960 DOI: 10.3390/ijms21072477] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 03/26/2020] [Accepted: 03/30/2020] [Indexed: 12/13/2022] Open
Abstract
Still unresolved is the question of how a lifetime accumulation of somatic gene copy number alterations impact organ functionality and aging and age-related pathologies. Such an issue appears particularly relevant in the broadly post-mitotic central nervous system (CNS), where non-replicative neurons are restricted in DNA-repair choices and are prone to accumulate DNA damage, as they remain unreplaced over a lifetime. Both DNA injuries and consecutive DNA-repair strategies are processes that can evoke extrachromosomal circular DNA species, apparently from either part of the genome. Due to their capacity to amplify gene copies and related transcripts, the individual cellular load of extrachromosomal circular DNAs will contribute to a dynamic pool of additional coding and regulatory chromatin elements. Analogous to tumor tissues, where the mosaicism of circular DNAs plays a well-characterized role in oncogene plasticity and drug resistance, we suggest involvement of the "circulome" also in the CNS. Accordingly, we summarize current knowledge on the molecular biogenesis, homeostasis and gene regulatory impacts of circular extrachromosomal DNA and propose, in light of recent discoveries, a critical role in CNS aging and neurodegeneration. Future studies will elucidate the influence of individual extrachromosomal DNA species according to their sequence complexity and regional distribution or cell-type-specific abundance.
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Affiliation(s)
- Quratul Ain
- Hans-Berger Department of Neurology, Jena University Hospital, 07747 Jena, Thuringia, Germany; (Q.A.); (C.S.); (D.W.); (O.W.W.)
| | - Christian Schmeer
- Hans-Berger Department of Neurology, Jena University Hospital, 07747 Jena, Thuringia, Germany; (Q.A.); (C.S.); (D.W.); (O.W.W.)
- Jena Center for Healthy Ageing, Jena University Hospital, 07747 Jena, Thuringia, Germany
| | - Diane Wengerodt
- Hans-Berger Department of Neurology, Jena University Hospital, 07747 Jena, Thuringia, Germany; (Q.A.); (C.S.); (D.W.); (O.W.W.)
| | - Otto W. Witte
- Hans-Berger Department of Neurology, Jena University Hospital, 07747 Jena, Thuringia, Germany; (Q.A.); (C.S.); (D.W.); (O.W.W.)
- Jena Center for Healthy Ageing, Jena University Hospital, 07747 Jena, Thuringia, Germany
| | - Alexandra Kretz
- Hans-Berger Department of Neurology, Jena University Hospital, 07747 Jena, Thuringia, Germany; (Q.A.); (C.S.); (D.W.); (O.W.W.)
- Jena Center for Healthy Ageing, Jena University Hospital, 07747 Jena, Thuringia, Germany
- Correspondence:
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33
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Nemirovich-Danchenko NM, Khodanovich MY. Telomerase Gene Editing in the Neural Stem Cells in vivo as a Possible New Approach against Brain Aging. RUSS J GENET+ 2020. [DOI: 10.1134/s1022795420040092] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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34
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Loe TK, Li JSZ, Zhang Y, Azeroglu B, Boddy MN, Denchi EL. Telomere length heterogeneity in ALT cells is maintained by PML-dependent localization of the BTR complex to telomeres. Genes Dev 2020; 34:650-662. [PMID: 32217664 PMCID: PMC7197349 DOI: 10.1101/gad.333963.119] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 02/26/2020] [Indexed: 12/11/2022]
Abstract
In this study, Loe et al. sought to understand ALT-associated PML bodies (APBs) and their function in the alternative lengthening of telomeres (ALT) pathway, a telomerase-independent mechanism of telomere extension that some cancer cells that use. Using CRISPR/Cas9 to delete PML and APB components from ALT-positive cells, they found that PML is required for the ALT mechanism, and that this necessity stems from APBs’ role in localizing the BLM–TOP3A–RMI (BTR) complex to ALT telomere ends, suggesting that BTR localization to telomeres is sufficient to sustain ALT activity. Telomeres consist of TTAGGG repeats bound by protein complexes that serve to protect the natural end of linear chromosomes. Most cells maintain telomere repeat lengths by using the enzyme telomerase, although there are some cancer cells that use a telomerase-independent mechanism of telomere extension, termed alternative lengthening of telomeres (ALT). Cells that use ALT are characterized, in part, by the presence of specialized PML nuclear bodies called ALT-associated PML bodies (APBs). APBs localize to and cluster telomeric ends together with telomeric and DNA damage factors, which led to the proposal that these bodies act as a platform on which ALT can occur. However, the necessity of APBs and their function in the ALT pathway has remained unclear. Here, we used CRISPR/Cas9 to delete PML and APB components from ALT-positive cells to cleanly define the function of APBs in ALT. We found that PML is required for the ALT mechanism, and that this necessity stems from APBs’ role in localizing the BLM–TOP3A–RMI (BTR) complex to ALT telomere ends. Strikingly, recruitment of the BTR complex to telomeres in a PML-independent manner bypasses the need for PML in the ALT pathway, suggesting that BTR localization to telomeres is sufficient to sustain ALT activity.
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Affiliation(s)
- Taylor K Loe
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, California 92037, USA
| | - Julia Su Zhou Li
- Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, California 92093, USA
| | - Yuxiang Zhang
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, California 92037, USA
| | - Benura Azeroglu
- Laboratory of Genome Integrity, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Michael Nicholas Boddy
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, California 92037, USA
| | - Eros Lazzerini Denchi
- Laboratory of Genome Integrity, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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35
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Sommer A, Royle NJ. ALT: A Multi-Faceted Phenomenon. Genes (Basel) 2020; 11:E133. [PMID: 32012790 PMCID: PMC7073516 DOI: 10.3390/genes11020133] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 01/17/2020] [Accepted: 01/22/2020] [Indexed: 01/13/2023] Open
Abstract
One of the hallmarks of cancer cells is their indefinite replicative potential, made possible by the activation of a telomere maintenance mechanism (TMM). The majority of cancers reactivate the reverse transcriptase, telomerase, to maintain their telomere length but a minority (10% to 15%) utilize an alternative lengthening of telomeres (ALT) pathway. Here, we review the phenotypes and molecular markers specific to ALT, and investigate the significance of telomere mutations and sequence variation in ALT cell lines. We also look at the recent advancements in understanding the different mechanisms behind ALT telomere elongation and finally, the progress made in identifying potential ALT-targeted therapies, including those already in use for the treatment of both hematological and solid tumors.
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Affiliation(s)
| | - Nicola J. Royle
- Department of Genetics and Genome Biology, University of Leicester, Leicester LE1 7RH, UK;
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36
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Sui J, Zhang S, Chen BPC. DNA-dependent protein kinase in telomere maintenance and protection. Cell Mol Biol Lett 2020; 25:2. [PMID: 31988640 PMCID: PMC6969447 DOI: 10.1186/s11658-020-0199-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 01/02/2020] [Indexed: 12/12/2022] Open
Abstract
This review focuses on DNA-dependent protein kinase (DNA-PK), which is the key regulator of canonical non-homologous end-joining (NHEJ), the predominant mechanism of DNA double-strand break (DSB) repair in mammals. DNA-PK consists of the DNA-binding Ku70/80 heterodimer and the catalytic subunit DNA-PKcs. They assemble at DNA ends, forming the active DNA-PK complex, which initiates NHEJ-mediated DSB repair. Paradoxically, both Ku and DNA-PKcs are associated with telomeres, and they play crucial roles in protecting the telomere against fusions. Herein, we discuss possible mechanisms and contributions of Ku and DNA-PKcs in telomere regulation.
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Affiliation(s)
- Jiangdong Sui
- 1Radiation Oncology Center, Chongqing University Cancer Hospital, Chongqing, 400030 China
| | - Shichuan Zhang
- 2Department of Radiation Oncology, Sichuan Cancer Hospital, Chengdu, China
| | - Benjamin P C Chen
- 3Department of Radiation Oncology, University of Texas Southwestern Medical Center, 2201 Inwood Rd., Dallas, TX 75390-9187 USA
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37
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Porreca RM, Herrera-Moyano E, Skourti E, Law PP, Gonzalez Franco R, Montoya A, Faull P, Kramer H, Vannier JB. TRF1 averts chromatin remodelling, recombination and replication dependent-break induced replication at mouse telomeres. eLife 2020; 9:49817. [PMID: 31934863 PMCID: PMC6986873 DOI: 10.7554/elife.49817] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Accepted: 01/11/2020] [Indexed: 12/29/2022] Open
Abstract
Telomeres are a significant challenge to DNA replication and are prone to replication stress and telomere fragility. The shelterin component TRF1 facilitates telomere replication but the molecular mechanism remains uncertain. By interrogating the proteomic composition of telomeres, we show that mouse telomeres lacking TRF1 undergo protein composition reorganisation associated with the recruitment of DNA damage response and chromatin remodellers. Surprisingly, mTRF1 suppresses the accumulation of promyelocytic leukemia (PML) protein, BRCA1 and the SMC5/6 complex at telomeres, which is associated with increased Homologous Recombination (HR) and TERRA transcription. We uncovered a previously unappreciated role for mTRF1 in the suppression of telomere recombination, dependent on SMC5 and also POLD3 dependent Break Induced Replication at telomeres. We propose that TRF1 facilitates S-phase telomeric DNA synthesis to prevent illegitimate mitotic DNA recombination and chromatin rearrangement.
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Affiliation(s)
- Rosa Maria Porreca
- Telomere Replication and Stability group, Medical Research Council - London Institute of Medical Sciences, London, United Kingdom.,Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Emilia Herrera-Moyano
- Telomere Replication and Stability group, Medical Research Council - London Institute of Medical Sciences, London, United Kingdom.,Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Eleni Skourti
- Telomere Replication and Stability group, Medical Research Council - London Institute of Medical Sciences, London, United Kingdom.,Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Pui Pik Law
- Telomere Replication and Stability group, Medical Research Council - London Institute of Medical Sciences, London, United Kingdom.,Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Roser Gonzalez Franco
- Telomere Replication and Stability group, Medical Research Council - London Institute of Medical Sciences, London, United Kingdom.,Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Alex Montoya
- Biological Mass Spectrometry and Proteomics, Medical Research Council - London Institute of Medical Sciences, London, United Kingdom
| | - Peter Faull
- Biological Mass Spectrometry and Proteomics, Medical Research Council - London Institute of Medical Sciences, London, United Kingdom.,The Francis Crick Institute, Proteomics Mass Spectrometry Science and Technology Platform, London, United Kingdom
| | - Holger Kramer
- Biological Mass Spectrometry and Proteomics, Medical Research Council - London Institute of Medical Sciences, London, United Kingdom
| | - Jean-Baptiste Vannier
- Telomere Replication and Stability group, Medical Research Council - London Institute of Medical Sciences, London, United Kingdom.,Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom
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38
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Zhao S, Wang F, Liu L. Alternative Lengthening of Telomeres (ALT) in Tumors and Pluripotent Stem Cells. Genes (Basel) 2019; 10:genes10121030. [PMID: 31835618 PMCID: PMC6947546 DOI: 10.3390/genes10121030] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 11/28/2019] [Accepted: 12/02/2019] [Indexed: 12/22/2022] Open
Abstract
A telomere consists of repeated DNA sequences (TTAGGG)n as part of a nucleoprotein structure at the end of the linear chromosome, and their progressive shortening induces DNA damage response (DDR) that triggers cellular senescence. The telomere can be maintained by telomerase activity (TA) in the majority of cancer cells (particularly cancer stem cells) and pluripotent stem cells (PSCs), which exhibit unlimited self-proliferation. However, some cells, such as telomerase-deficient cancer cells, can add telomeric repeats by an alternative lengthening of the telomeres (ALT) pathway, showing telomere length heterogeneity. In this review, we focus on the mechanisms of the ALT pathway and potential clinical implications. We also discuss the characteristics of telomeres in PSCs, thereby shedding light on the therapeutic significance of telomere length regulation in age-related diseases and regenerative medicine.
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Affiliation(s)
- Shuang Zhao
- College of Life Sciences, Nankai University, Tianjin 300071, China;
- State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin 300071, China
| | - Feng Wang
- Department of Genetics, School of Basic Medical Sciences, Tianjin Medical University, Tianjin 300070, China;
| | - Lin Liu
- College of Life Sciences, Nankai University, Tianjin 300071, China;
- State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin 300071, China
- Correspondence:
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Ravindranathan A, Diolaiti ME, Cimini BA, Stohr BA. In Situ Visualization of Telomere Length, Telomere Elongation, and TERT Expression in Single Cells. ACTA ACUST UNITED AC 2019; 85:e97. [PMID: 31763768 DOI: 10.1002/cpcb.97] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Telomerase plays a critical role in cancer and aging by adding hexa-nucleotide repeats to the ends of telomeres and extending the cellular proliferative lifespan. The very low level of telomerase expression in most cell populations and the difficulty of detecting telomere elongation in single cells have limited the study of telomerase expression and function in individual cells of a heterogeneous population. The method described in this article combines single-molecule detection (RNAscope) of telomerase reverse transcriptase (TERT) with our previously described TSQ1 assay for in situ monitoring of telomere extension, thereby enabling detection of TERT expression, telomere length, and telomere elongation in single cells and providing a unique approach for studying the factors that regulate telomere elongation by telomerase. © 2019 by John Wiley & Sons, Inc. Basic Protocol 1: TSQ1 lentivirus production Basic Protocol 2: TSQ1 lentiviral infection and plating Basic Protocol 3: RNAscope analysis Basic Protocol 4: TSQ1 PNA-FISH detection.
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Affiliation(s)
- Ajay Ravindranathan
- Department of Pathology, University of California, San Francisco, California
| | - Morgan E Diolaiti
- UCSF Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, California
| | | | - Bradley A Stohr
- Department of Pathology, University of California, San Francisco, California
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40
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TZAP Mutation Leads to Poor Prognosis of Patients with Breast Cancer †. ACTA ACUST UNITED AC 2019; 55:medicina55110748. [PMID: 31752241 PMCID: PMC6915578 DOI: 10.3390/medicina55110748] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 11/05/2019] [Accepted: 11/08/2019] [Indexed: 01/29/2023]
Abstract
Background and Objectives: ZBTB48 is a telomere-associated factor that has been renamed as telomeric zinc finger-associated protein (TZAP). It binds preferentially to long telomeres, competing with telomeric repeat factors 1 and 2. Materials and Methods: We analyzed the TZAP mutation in 128 breast carcinomas (BCs). In addition, its association with telomere length was investigated. Results: The TZAP mutation (c.1272 G > A, L424L) was found in 7.8% (10/128) of the BCs and was associated with the N0 stage. BCs with the TZAP mutation had longer telomeres than those without this mutation. Survival analysis showed that the TZAP mutation resulted in poorer overall survival. Conclusions: These results suggest that the TZAP mutation is a possible prognostic marker in BC.
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41
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Grandjenette C, Schnekenburger M, Gaigneaux A, Gérard D, Christov C, Mazumder A, Dicato M, Diederich M. Human telomerase reverse transcriptase depletion potentiates the growth-inhibitory activity of imatinib in chronic myeloid leukemia stem cells. Cancer Lett 2019; 469:468-480. [PMID: 31734352 DOI: 10.1016/j.canlet.2019.11.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 11/03/2019] [Accepted: 11/11/2019] [Indexed: 12/19/2022]
Abstract
Although tyrosine kinase inhibitors (TKIs) revolutionized the management of chronic myeloid leukemia (CML), resistance against TKIs and leukemia stem cell (LSC) persistence remain a clinical concern. Therefore, new therapeutic strategies combining conventional and novel therapies are urgently needed. Since telomerase is involved in oncogenesis and tumor progression but is silent in most human normal somatic cells, it may be an interesting target for CML therapy by selectively targeting cancer cells while minimizing effects on normal cells. Here, we report that hTERT expression is associated with CML disease progression. We also provide evidence that hTERT-deficient K-562 cells do not display telomere shortening and that telomere length is maintained through the ALT pathway. Furthermore, we show that hTERT depletion exerts a growth-inhibitory effect in K-562 cells and potentiates imatinib through alteration of cell cycle progression leading to a senescence-like phenotype. Finally, we demonstrate that hTERT depletion potentiates the imatinib-induced reduction of the ALDH+-LSC population. Altogether, our results suggest that the combination of telomerase and TKI should be considered as an attractive strategy to treat CML patients to eradicate cancer cells and prevent relapse by targeting LSCs.
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Affiliation(s)
- Cindy Grandjenette
- Laboratoire de Biologie Moléculaire Du Cancer, Hôpital Kirchberg, 9, Rue Edward Steichen, L-2540, Luxembourg
| | - Michael Schnekenburger
- Laboratoire de Biologie Moléculaire Du Cancer, Hôpital Kirchberg, 9, Rue Edward Steichen, L-2540, Luxembourg
| | - Anthoula Gaigneaux
- Laboratoire de Biologie Moléculaire Du Cancer, Hôpital Kirchberg, 9, Rue Edward Steichen, L-2540, Luxembourg
| | - Déborah Gérard
- Laboratoire de Biologie Moléculaire Du Cancer, Hôpital Kirchberg, 9, Rue Edward Steichen, L-2540, Luxembourg
| | - Christo Christov
- Service Commun de Microscopie, Université de Lorraine, 54000, Nancy, France
| | - Aloran Mazumder
- Department of Pharmacy, College of Pharmacy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08626, South Korea
| | - Mario Dicato
- Laboratoire de Biologie Moléculaire Du Cancer, Hôpital Kirchberg, 9, Rue Edward Steichen, L-2540, Luxembourg
| | - Marc Diederich
- Department of Pharmacy, College of Pharmacy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08626, South Korea.
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42
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Porreca RM, Glousker G, Awad A, Matilla Fernandez MI, Gibaud A, Naucke C, Cohen SB, Bryan TM, Tzfati Y, Draskovic I, Londoño-Vallejo A. Human RTEL1 stabilizes long G-overhangs allowing telomerase-dependent over-extension. Nucleic Acids Res 2019. [PMID: 29522136 PMCID: PMC5961080 DOI: 10.1093/nar/gky173] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Telomere maintenance protects the cell against genome instability and senescence. Accelerated telomere attrition is a characteristic of premature aging syndromes including Dyskeratosis congenita (DC). Mutations in hRTEL1 are associated with a severe form of DC called Hoyeraal-Hreidarsson syndrome (HHS). HHS patients carry short telomeres and HHS cells display telomere damage. Here we investigated how hRTEL1 contributes to telomere maintenance in human primary as well as tumor cells. Transient depletion of hRTEL1 resulted in rapid telomere shortening only in the context of telomerase-positive cells with very long telomeres and high levels of telomerase. The effect of hRTEL1 on telomere length is telomerase dependent without impacting telomerase biogenesis or targeting of the enzyme to telomeres. Instead, RTEL1 depletion led to a decrease in both G-overhang content and POT1 association with telomeres with limited telomere uncapping. Strikingly, overexpression of POT1 restored telomere length but not the overhang, demonstrating that G-overhang loss is the primary defect caused by RTEL1 depletion. We propose that hRTEL1 contributes to the maintenance of long telomeres by preserving long G-overhangs, thereby facilitating POT1 binding and elongation by telomerase.
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Affiliation(s)
- Rosa M Porreca
- Institut Curie, PSL Research University, Sorbonne Universités, CNRS UMR3244 Telomere and cancer lab, 75005 Paris, France
| | - Galina Glousker
- Department of Genetics, The Silberman Institute of Life Science, The Hebrew University of Jerusalem, Safra Campus-Givat Ram, Jerusalem 91904, Israel
| | - Aya Awad
- Department of Genetics, The Silberman Institute of Life Science, The Hebrew University of Jerusalem, Safra Campus-Givat Ram, Jerusalem 91904, Israel
| | | | - Anne Gibaud
- Institut Curie, PSL Research University, Sorbonne Universités, CNRS UMR3244 Telomere and cancer lab, 75005 Paris, France
| | - Christian Naucke
- Institut Curie, PSL Research University, Sorbonne Universités, CNRS UMR3244 Telomere and cancer lab, 75005 Paris, France
| | - Scott B Cohen
- Children's Medical Research Institute, University of Sydney, Westmead, NSW 2145, Australia
| | - Tracy M Bryan
- Children's Medical Research Institute, University of Sydney, Westmead, NSW 2145, Australia
| | - Yehuda Tzfati
- Department of Genetics, The Silberman Institute of Life Science, The Hebrew University of Jerusalem, Safra Campus-Givat Ram, Jerusalem 91904, Israel
| | - Irena Draskovic
- Institut Curie, PSL Research University, Sorbonne Universités, CNRS UMR3244 Telomere and cancer lab, 75005 Paris, France
| | - Arturo Londoño-Vallejo
- Institut Curie, PSL Research University, Sorbonne Universités, CNRS UMR3244 Telomere and cancer lab, 75005 Paris, France
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Abstract
Telomeres are specialised structures at the end of linear chromosomes. They consist of tandem repeats of the hexanucleotide sequence TTAGGG, as well as a protein complex called shelterin. Together, they form a protective loop structure against chromosome fusion and degradation. Shortening or damage to telomeres and opening of the loop induce an uncapped state that triggers a DNA damage response resulting in senescence or apoptosis.Average telomere length, usually measured in human blood lymphocytes, was thought to be a biomarker for ageing, survival and mortality. However, it becomes obvious that regulation of telomere length is very complex and involves multiple processes. For example, the "end replication problem" during DNA replication as well as oxidative stress are responsible for the shortening of telomeres. In contrast, telomerase activity can potentially counteract telomere shortening when it is able to access and interact with telomeres. However, while highly active during development and in cancer cells, the enzyme is down-regulated in most human somatic cells with a few exceptions such as human lymphocytes. In addition, telomeres can be transcribed, and the transcription products called TERRA are involved in telomere length regulation.Thus, telomere length and their integrity are regulated at many different levels, and we only start to understand this process under conditions of increased oxidative stress, inflammation and during diseases as well as the ageing process.This chapter aims to describe our current state of knowledge on telomeres and telomerase and their regulation in order to better understand their role for the ageing process.
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44
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Doksani Y. The Response to DNA Damage at Telomeric Repeats and Its Consequences for Telomere Function. Genes (Basel) 2019; 10:genes10040318. [PMID: 31022960 PMCID: PMC6523756 DOI: 10.3390/genes10040318] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 04/13/2019] [Accepted: 04/18/2019] [Indexed: 01/17/2023] Open
Abstract
Telomeric repeats, coated by the shelterin complex, prevent inappropriate activation of the DNA damage response at the ends of linear chromosomes. Shelterin has evolved distinct solutions to protect telomeres from different aspects of the DNA damage response. These solutions include formation of t-loops, which can sequester the chromosome terminus from DNA-end sensors and inhibition of key steps in the DNA damage response. While blocking the DNA damage response at chromosome ends, telomeres make wide use of many of its players to deal with exogenous damage and replication stress. This review focuses on the interplay between the end-protection functions and the response to DNA damage occurring inside the telomeric repeats, as well as on the consequences that telomere damage has on telomere structure and function.
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Affiliation(s)
- Ylli Doksani
- IFOM, The FIRC Institute of Molecular Oncology, via Adamello 16, 20139 Milan, Italy.
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45
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Mensà E, Latini S, Ramini D, Storci G, Bonafè M, Olivieri F. The telomere world and aging: Analytical challenges and future perspectives. Ageing Res Rev 2019; 50:27-42. [PMID: 30615937 DOI: 10.1016/j.arr.2019.01.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 11/15/2018] [Accepted: 01/03/2019] [Indexed: 12/12/2022]
Abstract
Telomeres, the terminal nucleoprotein structures of eukaryotic chromosomes, play pleiotropic functions in cellular and organismal aging. Telomere length (TL) varies throughout life due to the influence of genetic factors and to a complex balancing between "shortening" and "elongation" signals. Telomerase, the only enzyme that can elongate a telomeric DNA chain, and telomeric repeat-containing RNA (TERRA), a long non-coding RNA involved in looping maintenance, play key roles in TL during life. Despite recent advances in the knowledge of TL, TERRA and telomerase activity (TA) biology and their measurement techniques, the experimental and theoretical issues involved raise a number of problems that should carefully be considered by researchers approaching the "telomere world". The increasing use of such parameters - hailed as promising clinically relevant biomarkers - has failed to be paralleled by the development of automated and standardized measurement technology. Consequently, associating given TL values to specific pathological conditions involves on the one hand technological issues and on the other clinical-biological issues related to the planning of clinically relevant association studies. Addressing these issues would help avoid major biases in association studies involving TL and a number of outcomes, especially those focusing on psychological and bio-behavioral variables. The main challenge in telomere research is the development of accurate and reliable measurement methods to achieve simple and sensitive TL, TERRA, and TA detection. The discovery of the localization of telomeres and TERRA in cellular and extracellular compartments had added an additional layer of complexity to the measurement of these age-related biomarkers. Since combined analysis of TL, TERRA and TA may well provide more exhaustive clinical information than a single parameter, we feel it is important for researchers in the various fields to become familiar with their most common measurement techniques and to be aware of the respective merits and drawbacks of these approaches.
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Affiliation(s)
- Emanuela Mensà
- Department of Clinical and Molecular Sciences, DISCLIMO, Università Politecnica delle Marche, Ancona, Italy
| | - Silvia Latini
- Department of Clinical and Molecular Sciences, DISCLIMO, Università Politecnica delle Marche, Ancona, Italy
| | - Deborah Ramini
- Department of Clinical and Molecular Sciences, DISCLIMO, Università Politecnica delle Marche, Ancona, Italy
| | - Gianluca Storci
- Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, Bologna, Italy; Interdepartmental Centre "L. Galvani" (CIG), University of Bologna, Bologna, Italy
| | - Massimiliano Bonafè
- Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, Bologna, Italy; Interdepartmental Centre "L. Galvani" (CIG), University of Bologna, Bologna, Italy; Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRST), IRCCS, Biosciences Laboratory, Meldola, Italy
| | - Fabiola Olivieri
- Department of Clinical and Molecular Sciences, DISCLIMO, Università Politecnica delle Marche, Ancona, Italy; Center of Clinical Pathology and Innovative Therapy, IRCCS INRCA, Ancona, Italy.
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46
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Zhang Z, Zhang T, Ge Y, Tang M, Ma W, Zhang Q, Gong S, Wright WE, Shay J, Liu H, Zhao Y. 2D gel electrophoresis reveals dynamics of t-loop formation during the cell cycle and t-loop in maintenance regulated by heterochromatin state. J Biol Chem 2019; 294:6645-6656. [PMID: 30819801 DOI: 10.1074/jbc.ra119.007677] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 02/20/2019] [Indexed: 12/15/2022] Open
Abstract
Linear chromosome ends are capped by telomeres that have been previously reported to adopt a t-loop structure. The lack of simple methods for detecting t-loops has hindered progress in understanding the dynamics of t-loop formation and its function in protecting chromosome ends. Here, we employed a classical two-dimensional agarose gel method (2D gel method) to innovatively apply to t-loop detection. Briefly, restriction fragments of genomic DNA were separated in a 2D gel, and the telomere sequence was detected by in-gel hybridization with telomeric probe. Using this method, we found that t-loops are present throughout the cell cycle, and t-loop formation tightly couples to telomere replication. We also observed that t-loop abundance positively correlates with chromatin condensation, i.e. cells with less compact telomeric chromatin (ALT cells and trichostatin A (TSA)-treated HeLa cells) exhibited fewer t-loops. Moreover, we observed that telomere dysfunction-induced foci, ALT-associated promyelocytic leukemia bodies, and telomere sister chromatid exchanges are activated upon TSA-induced loss of t-loops. These findings confirm the importance of the t-loop in protecting linear chromosomes from damage or illegitimate recombination.
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Affiliation(s)
- Zepeng Zhang
- From the MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Tianpeng Zhang
- From the MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Yuanlong Ge
- From the MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Mengfan Tang
- From the MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Wenbin Ma
- From the MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Qinfen Zhang
- From the MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Shengzhao Gong
- Department of Chemical Engineering, Guangdong Industry Technical College, Guangzhou 510006, China
| | - Woodring E Wright
- the Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, and
| | - Jerry Shay
- the Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, and
| | - Haiying Liu
- From the MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China,
| | - Yong Zhao
- From the MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China,
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Harrington L, Pucci F. In medio stat virtus: unanticipated consequences of telomere dysequilibrium. Philos Trans R Soc Lond B Biol Sci 2019; 373:rstb.2016.0444. [PMID: 29335368 PMCID: PMC5784064 DOI: 10.1098/rstb.2016.0444] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/07/2017] [Indexed: 12/13/2022] Open
Abstract
The integrity of chromosome ends, or telomeres, depends on myriad processes that must balance the need to compact and protect the telomeric, G-rich DNA from detection as a double-stranded DNA break, and yet still permit access to enzymes that process, replicate and maintain a sufficient reserve of telomeric DNA. When unable to maintain this equilibrium, erosion of telomeres leads to perturbations at or near the telomeres themselves, including loss of binding by the telomere protective complex, shelterin, and alterations in transcription and post-translational modifications of histones. Although the catastrophic consequences of full telomere de-protection are well described, recent evidence points to other, less obvious perturbations that arise when telomere length equilibrium is altered. For example, critically short telomeres also perturb DNA methylation and histone post-translational modifications at distal sites throughout the genome. In murine stem cells for example, this dysregulated chromatin leads to inappropriate suppression of pluripotency regulator factors such as Nanog. This review summarizes these recent findings, with an emphasis on how these genome-wide, telomere-induced perturbations can have profound consequences on cell function and fate. This article is part of the theme issue ‘Understanding diversity in telomere dynamics’.
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Affiliation(s)
- Lea Harrington
- Wellcome Trust Centre for Cell Biology, School of Biological Sciences, College of Science and Engineering, University of Edinburgh, Mayfield Road, Edinburgh EH9 3JR, UK
| | - Fabio Pucci
- Wellcome Trust Centre for Cell Biology, School of Biological Sciences, College of Science and Engineering, University of Edinburgh, Mayfield Road, Edinburgh EH9 3JR, UK
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Abstract
The maintenance of genome stability in eukaryotic cells relies on accurate and efficient replication along each chromosome following every cell division. The terminal position, repetitive sequence, and structural complexities of the telomeric DNA make the telomere an inherently difficult region to replicate within the genome. Thus, despite functioning to protect genome stability mammalian telomeres are also a source of replication stress and have been recognized as common fragile sites within the genome. Telomere fragility is exacerbated at telomeres that rely on the Alternative Lengthening of Telomeres (ALT) pathway. Like common fragile sites, ALT telomeres are prone to chromosome breaks and are frequent sites of recombination suggesting that ALT telomeres are subjected to chronic replication stress. Here, we will review the features of telomeric DNA that challenge the replication machinery and also how the cell overcomes these challenges to maintain telomere stability and ensure the faithful duplication of the human genome.
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Affiliation(s)
- Emily Mason-Osann
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA, USA
- Department of Medicine, Cancer Center, Boston University School of Medicine, Boston, MA, USA
| | - Himabindu Gali
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA, USA
- Department of Medicine, Cancer Center, Boston University School of Medicine, Boston, MA, USA
| | - Rachel Litman Flynn
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA, USA.
- Department of Medicine, Cancer Center, Boston University School of Medicine, Boston, MA, USA.
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Khoo LT, Chen LY. Role of the cGAS-STING pathway in cancer development and oncotherapeutic approaches. EMBO Rep 2018; 19:embr.201846935. [PMID: 30446584 DOI: 10.15252/embr.201846935] [Citation(s) in RCA: 100] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 10/26/2018] [Accepted: 10/26/2018] [Indexed: 12/19/2022] Open
Abstract
The cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway mediates anti-microbial innate immunity by inducing the production of type I interferons (IFNs) and inflammatory cytokines upon recognition of microbial DNA. Recent studies reveal that self-DNA from tumors and by-products of genomic instability also activates the cGAS-STING pathway and either promotes or inhibits tumor development. This has led to the development of cancer therapeutics using STING agonists alone and in combination with conventional cancer treatment or immune checkpoint targeting. On the other hand, for cancers lacking the cGAS-STING pathway and thus a regular innate immunity response, oncolytic virus therapy has been shown to have therapeutic potential. We here review and discuss the dichotomous roles of the cGAS-STING pathway in cancer development and therapeutic approaches.
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Affiliation(s)
- Li Teng Khoo
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Liuh-Yow Chen
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
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50
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Mukherjee AK, Sharma S, Sengupta S, Saha D, Kumar P, Hussain T, Srivastava V, Roy SD, Shay JW, Chowdhury S. Telomere length-dependent transcription and epigenetic modifications in promoters remote from telomere ends. PLoS Genet 2018; 14:e1007782. [PMID: 30439955 PMCID: PMC6264879 DOI: 10.1371/journal.pgen.1007782] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 11/29/2018] [Accepted: 10/23/2018] [Indexed: 12/03/2022] Open
Abstract
Telomere-binding proteins constituting the shelterin complex have been studied primarily for telomeric functions. However, mounting evidence shows non-telomeric binding and gene regulation by shelterin factors. This raises a key question—do telomeres impact binding of shelterin proteins at distal non-telomeric sites? Here we show that binding of the telomere-repeat-binding-factor-2 (TRF2) at promoters ~60 Mb from telomeres depends on telomere length in human cells. Promoter TRF2 occupancy was depleted in cells with elongated telomeres resulting in altered TRF2-mediated transcription of distal genes. In addition, histone modifications—activation (H3K4me1 and H3K4me3) as well as silencing marks (H3K27me3)—at distal promoters were telomere length-dependent. These demonstrate that transcription, and the epigenetic state, of telomere-distal promoters can be influenced by telomere length. Molecular links between telomeres and the extra-telomeric genome, emerging from findings here, might have important implications in telomere-related physiology, particularly ageing and cancer. Telomeres (special DNA-protein assemblies that protect chromosome ends) affect ageing and diseases such as cancer. Although this has been recognized for many years, biological processes that connect telomeres to ageing, cancer and other cellular functions remain to be fully understood. Certain proteins, believed to be only telomere-associated, engage DNA outside telomeres. This raises an interesting question. Does telomere length influence how telomere-binding proteins associate with DNA at regions distal from telomeres. If so, how does this impact function? Motivated by these questions, in the present studies we tested if extra-telomeric binding of the well-known telomere-repeat-binding-actor-2 (TRF2) depends on telomere length. Our results show that the level of DNA-bound TRF2 at telomere-distal sites changes as telomeres shorten or elongate. Consequently, TRF2-mediated gene regulation affects many genes. Notably, histone modifications that dictate chromatin compaction and access to regulatory factors, at sites distant from telomere ends also depended on telomere length. Together, this links the state of telomeres to gene regulation and epigenetics directly in ways not previously appreciated that might impact a more complete understanding of molecular processes underlying ageing and cancer.
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Affiliation(s)
- Ananda Kishore Mukherjee
- Genomics and Molecular Medicine Unit, CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
- Academy of Scientific and Innovative Research, CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
| | - Shalu Sharma
- Genomics and Molecular Medicine Unit, CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
- Academy of Scientific and Innovative Research, CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
| | - Suman Sengupta
- Genomics and Molecular Medicine Unit, CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
| | - Dhurjhoti Saha
- Genomics and Molecular Medicine Unit, CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
| | - Pankaj Kumar
- Academy of Scientific and Innovative Research, CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
- G.N.R. Knowledge Centre for Genome Informatics, CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
| | - Tabish Hussain
- Genomics and Molecular Medicine Unit, CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
| | - Vivek Srivastava
- Genomics and Molecular Medicine Unit, CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
| | - Sumitabho Deb Roy
- Genomics and Molecular Medicine Unit, CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
| | - Jerry W. Shay
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Shantanu Chowdhury
- Genomics and Molecular Medicine Unit, CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
- Academy of Scientific and Innovative Research, CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
- G.N.R. Knowledge Centre for Genome Informatics, CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
- * E-mail:
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