1
|
Xiurong D, Xin Z, Neng Y, Li D, Yanzhou W, Kaijian L, Zhiqing L. Genetically engineered mouse model of HPV16 E6-E7 with vaginal-cervical intraepithelial neoplasia and decreased immunity. Heliyon 2024; 10:e29881. [PMID: 38765051 PMCID: PMC11096975 DOI: 10.1016/j.heliyon.2024.e29881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 04/14/2024] [Accepted: 04/17/2024] [Indexed: 05/21/2024] Open
Abstract
Objective To construct models of high-risk human papillomavirus (HPV) infection with precancerous lesions or cervical cancer and explore the immune function. Methods Using CRISPR/Cas9, the expression vector HPV16-E6-E7-Rosa26 was microinjected into fertilized eggs of C57BL/6 N mice using homologous recombination, and the F0 generation was obtained for reproduction. Then, the formation of precancerous lesions was promoted via intramuscular injection of estradiol. Presence of precancerous cervical-vaginal intraepithelial lesions, Ki67 and p16 expression levels, and CD8+ T cell proportions in the spleen were evaluated. Results Two F0 generation mice exhibited correct the homologous recombination. Seven positive mice were identified in the F1 generation. After breeding and mating, 25 homozygous and 11 heterozygous HPV16-E6-E7-engineered mice were obtained from the F2 generation. After estradiol benzoate treatment, the cervical-vaginal epithelium appeared as precancerous lesions with positive Ki67 and p16 expression. The percentage of CD8+ T cells decreased. Conclusion HPV16-E6-E7-Rosa26 induced low immune function in mice, and provides a good model for the basic research of the mechanisms of action of HPV infection-associated precancerous lesions or cervical cancer.
Collapse
Affiliation(s)
- Du Xiurong
- The Army Medical University, Chongqing, 400038, China
- Department of Obstetrics and Gynecology, Southwest Hospital of the Third Military Medical University (The first Affiliated Hospital of the Army Medical University), Chongqing, 400038, China
| | - Zhou Xin
- The Army Medical University, Chongqing, 400038, China
- Department of Obstetrics and Gynecology, Southwest Hospital of the Third Military Medical University (The first Affiliated Hospital of the Army Medical University), Chongqing, 400038, China
| | - Yang Neng
- Department of Obstetrics and Gynecology, Southwest Hospital of the Third Military Medical University (The first Affiliated Hospital of the Army Medical University), Chongqing, 400038, China
| | - Deng Li
- Department of Obstetrics and Gynecology, Southwest Hospital of the Third Military Medical University (The first Affiliated Hospital of the Army Medical University), Chongqing, 400038, China
| | - Wang Yanzhou
- Department of Obstetrics and Gynecology, Southwest Hospital of the Third Military Medical University (The first Affiliated Hospital of the Army Medical University), Chongqing, 400038, China
| | - Ling Kaijian
- Department of Obstetrics and Gynecology, Southwest Hospital of the Third Military Medical University (The first Affiliated Hospital of the Army Medical University), Chongqing, 400038, China
| | - Liang Zhiqing
- The Army Medical University, Chongqing, 400038, China
- Department of Obstetrics and Gynecology, Southwest Hospital of the Third Military Medical University (The first Affiliated Hospital of the Army Medical University), Chongqing, 400038, China
| |
Collapse
|
2
|
Agabekian IA, Abdulkina LR, Lushnenko AY, Young PG, Valeeva LR, Boskovic O, Lilly EG, Sharipova MR, Shippen DE, Juenger TE, Shakirov EV. Arabidopsis AN3 and OLIGOCELLULA genes link telomere maintenance mechanisms with cell division and expansion control. PLANT MOLECULAR BIOLOGY 2024; 114:65. [PMID: 38816532 DOI: 10.1007/s11103-024-01457-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Accepted: 04/23/2024] [Indexed: 06/01/2024]
Abstract
Telomeres are conserved chromosomal structures necessary for continued cell division and proliferation. In addition to the classical telomerase pathway, multiple other genes including those involved in ribosome metabolism and chromatin modification contribute to telomere length maintenance. We previously reported that Arabidopsis thaliana ribosome biogenesis genes OLI2/NOP2A, OLI5/RPL5A and OLI7/RPL5B have critical roles in telomere length regulation. These three OLIGOCELLULA genes were also shown to function in cell proliferation and expansion control and to genetically interact with the transcriptional co-activator ANGUSTIFOLIA3 (AN3). Here we show that AN3-deficient plants progressively lose telomeric DNA in early homozygous mutant generations, but ultimately establish a new shorter telomere length setpoint by the fifth mutant generation with a telomere length similar to oli2/nop2a -deficient plants. Analysis of double an3 oli2 mutants indicates that the two genes are epistatic for telomere length control. Telomere shortening in an3 and oli mutants is not caused by telomerase inhibition; wild type levels of telomerase activity are detected in all analyzed mutants in vitro. Late generations of an3 and oli mutants are prone to stem cell damage in the root apical meristem, implying that genes regulating telomere length may have conserved functional roles in stem cell maintenance mechanisms. Multiple instances of anaphase fusions in late generations of oli5 and oli7 mutants were observed, highlighting an unexpected effect of ribosome biogenesis factors on chromosome integrity. Overall, our data implicate AN3 transcription coactivator and OLIGOCELLULA proteins in the establishment of telomere length set point in plants and further suggest that multiple regulators with pleiotropic functions can connect telomere biology with cell proliferation and cell expansion pathways.
Collapse
Affiliation(s)
- Inna A Agabekian
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Republic of Tatarstan, Kazan, 420008, Russia
| | - Liliia R Abdulkina
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Republic of Tatarstan, Kazan, 420008, Russia
| | - Alina Y Lushnenko
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Republic of Tatarstan, Kazan, 420008, Russia
| | - Pierce G Young
- Department of Biochemistry and Biophysics, Texas A&M University, 2128 TAMU, College Station, Texas, 77843-2128, USA
| | - Lia R Valeeva
- Department of Biological Sciences, College of Science, Marshall University, Huntington, West Virginia, 25701, USA
| | - Olivia Boskovic
- Department of Biological Sciences, College of Science, Marshall University, Huntington, West Virginia, 25701, USA
| | - Ethan G Lilly
- Department of Biological Sciences, College of Science, Marshall University, Huntington, West Virginia, 25701, USA
| | - Margarita R Sharipova
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Republic of Tatarstan, Kazan, 420008, Russia
| | - Dorothy E Shippen
- Department of Biochemistry and Biophysics, Texas A&M University, 2128 TAMU, College Station, Texas, 77843-2128, USA.
| | - Thomas E Juenger
- Department of Integrative Biology, University of Texas at Austin, Austin, Texas, 78712, USA.
| | - Eugene V Shakirov
- Department of Biological Sciences, College of Science, Marshall University, Huntington, West Virginia, 25701, USA.
- Department of Biomedical Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia, 25755, USA.
| |
Collapse
|
3
|
Hindle J, Williams A, Kim Y, Kim D, Patil K, Khatkar P, Osgood Q, Nelson C, Routenberg DA, Howard M, Liotta LA, Kashanchi F, Branscome H. hTERT-Immortalized Mesenchymal Stem Cell-Derived Extracellular Vesicles: Large-Scale Manufacturing, Cargo Profiling, and Functional Effects in Retinal Epithelial Cells. Cells 2024; 13:861. [PMID: 38786083 PMCID: PMC11120263 DOI: 10.3390/cells13100861] [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: 04/13/2024] [Revised: 05/07/2024] [Accepted: 05/14/2024] [Indexed: 05/25/2024] Open
Abstract
As the economic burden associated with vision loss and ocular damage continues to rise, there is a need to explore novel treatment strategies. Extracellular vesicles (EVs) are enriched with various biological cargo, and there is abundant literature supporting the reparative and immunomodulatory properties of stem cell EVs across a broad range of pathologies. However, one area that requires further attention is the reparative effects of stem cell EVs in the context of ocular damage. Additionally, most of the literature focuses on EVs isolated from primary stem cells; the use of EVs isolated from human telomerase reverse transcriptase (hTERT)-immortalized stem cells has not been thoroughly examined. Using our large-scale EV-manufacturing platform, we reproducibly manufactured EVs from hTERT-immortalized mesenchymal stem cells (MSCs) and employed various methods to characterize and profile their associated cargo. We also utilized well-established cell-based assays to compare the effects of these EVs on both healthy and damaged retinal pigment epithelial cells. To the best of our knowledge, this is the first study to establish proof of concept for reproducible, large-scale manufacturing of hTERT-immortalized MSC EVs and to investigate their potential reparative properties against damaged retinal cells. The results from our studies confirm that hTERT-immortalized MSC EVs exert reparative effects in vitro that are similar to those observed in primary MSC EVs. Therefore, hTERT-immortalized MSCs may represent a more consistent and reproducible platform than primary MSCs for generating EVs with therapeutic potential.
Collapse
Affiliation(s)
| | - Anastasia Williams
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, Manassas, VA 20110, USA (K.P.)
| | - Yuriy Kim
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, Manassas, VA 20110, USA (K.P.)
| | | | - Kajal Patil
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, Manassas, VA 20110, USA (K.P.)
| | - Pooja Khatkar
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, Manassas, VA 20110, USA (K.P.)
| | | | - Collin Nelson
- Meso Scale Diagnostics, L.L.C., Rockville, MD 20850, USA (D.A.R.)
| | | | - Marissa Howard
- Center for Applied Proteomics and Molecular Medicine, George Mason University, Manassas, VA 20110, USA
| | - Lance A. Liotta
- Center for Applied Proteomics and Molecular Medicine, George Mason University, Manassas, VA 20110, USA
| | - Fatah Kashanchi
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, Manassas, VA 20110, USA (K.P.)
| | - Heather Branscome
- ATCC, Manassas, VA 20110, USA
- Laboratory of Molecular Virology, School of Systems Biology, George Mason University, Manassas, VA 20110, USA (K.P.)
| |
Collapse
|
4
|
Audry J, Zhang H, Kerr C, Berkner KL, Runge K. Ccq1 restrains Mre11-mediated degradation to distinguish short telomeres from double-strand breaks. Nucleic Acids Res 2024; 52:3722-3739. [PMID: 38321948 PMCID: PMC11040153 DOI: 10.1093/nar/gkae044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 12/21/2023] [Accepted: 01/12/2024] [Indexed: 02/08/2024] Open
Abstract
Telomeres protect chromosome ends and are distinguished from DNA double-strand breaks (DSBs) by means of a specialized chromatin composed of DNA repeats bound by a multiprotein complex called shelterin. We investigated the role of telomere-associated proteins in establishing end-protection by studying viable mutants lacking these proteins. Mutants were studied using a Schizosaccharomyces pombe model system that induces cutting of a 'proto-telomere' bearing telomere repeats to rapidly form a new stable chromosomal end, in contrast to the rapid degradation of a control DSB. Cells lacking the telomere-associated proteins Taz1, Rap1, Poz1 or Rif1 formed a chromosome end that was stable. Surprisingly, cells lacking Ccq1, or impaired for recruiting Ccq1 to the telomere, converted the cleaved proto-telomere to a rapidly degraded DSB. Ccq1 recruits telomerase, establishes heterochromatin and affects DNA damage checkpoint activation; however, these functions were separable from protection of the new telomere by Ccq1. In cells lacking Ccq1, telomere degradation was greatly reduced by eliminating the nuclease activity of Mre11 (part of the Mre11-Rad50-Nbs1/Xrs2 DSB processing complex), and higher amounts of nuclease-deficient Mre11 associated with the new telomere. These results demonstrate a novel function for S. pombe Ccq1 to effect end-protection by restraining Mre11-dependent degradation of the DNA end.
Collapse
Affiliation(s)
- Julien Audry
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195, USA
| | - Haitao Zhang
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195, USA
| | - Carly Kerr
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195, USA
| | - Kathleen L Berkner
- Department of Cardiovascular and Metabolic Sciences, Cleveland Clinic Foundation, Cleveland, OH 44195, USA
| | - Kurt W Runge
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195, USA
- Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, OH 44106, USA
| |
Collapse
|
5
|
Savage SA. Telomere length and cancer risk: finding Goldilocks. Biogerontology 2024; 25:265-278. [PMID: 38109000 DOI: 10.1007/s10522-023-10080-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Accepted: 11/13/2023] [Indexed: 12/19/2023]
Abstract
Telomeres are the nucleoprotein complex at chromosome ends essential in genomic stability. Baseline telomere length (TL) is determined by rare and common germline genetic variants but shortens with age and is susceptible to certain environmental exposures. Cellular senescence or apoptosis are normally triggered when telomeres reach a critically short length, but cancer cells overcome these protective mechanisms and continue to divide despite chromosomal instability. Rare germline variants in telomere maintenance genes cause exceedingly short telomeres for age (< 1st percentile) and the telomere biology disorders, which are associated with elevated risks of bone marrow failure, myelodysplastic syndrome, acute myeloid leukemia, and squamous cell carcinoma of the head/neck and anogenital regions. Long telomeres due to rare germline variants in the same or different telomere maintenance genes are associated with elevated risks of other cancers, such as chronic lymphocytic leukemia or sarcoma. Early epidemiology studies of TL in the general population lacked reproducibility but new methods, including creation of a TL polygenic score using common variants, have found longer telomeres associated with excess risks of renal cell carcinoma, glioma, lung cancer, and others. It has become clear that when it comes to TL and cancer etiology, not too short, not too long, but "just right" telomeres are important in minimizing cancer risk.
Collapse
Affiliation(s)
- Sharon A Savage
- Clinical Genetics Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, 9609 Medical Center Drive, 6E456, Bethesda, MD, 20892-6772, USA.
| |
Collapse
|
6
|
Bartle L, Wellinger RJ. Methods that shaped telomerase research. Biogerontology 2024; 25:249-263. [PMID: 37903970 PMCID: PMC10998806 DOI: 10.1007/s10522-023-10073-8] [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: 08/08/2023] [Accepted: 09/30/2023] [Indexed: 11/01/2023]
Abstract
Telomerase, the ribonucleoprotein (RNP) responsible for telomere maintenance, has a complex life. Complex in that it is made of multiple proteins and an RNA, and complex because it undergoes many changes, and passes through different cell compartments. As such, many methods have been developed to discover telomerase components, delve deep into understanding its structure and function and to figure out how telomerase biology ultimately relates to human health and disease. While some old gold-standard methods are still key for determining telomere length and measuring telomerase activity, new technologies are providing promising new ways to gain detailed information that we have never had access to before. Therefore, we thought it timely to briefly review the methods that have revealed information about the telomerase RNP and outline some of the remaining questions that could be answered using new methodology.
Collapse
Affiliation(s)
- Louise Bartle
- Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Applied Cancer Research Pavilion, 3201 rue Jean-Mignault, Sherbrooke, QC, J1E 4K8, Canada
| | - Raymund J Wellinger
- Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Applied Cancer Research Pavilion, 3201 rue Jean-Mignault, Sherbrooke, QC, J1E 4K8, Canada.
| |
Collapse
|
7
|
Scelfo A, Angrisani A, Grillo M, Barnes BM, Muyas F, Sauer CM, Leung CWB, Dumont M, Grison M, Mazaud D, Garnier M, Guintini L, Nelson L, Esashi F, Cortés-Ciriano I, Taylor SS, Déjardin J, Wilhelm T, Fachinetti D. Specialized replication mechanisms maintain genome stability at human centromeres. Mol Cell 2024; 84:1003-1020.e10. [PMID: 38359824 DOI: 10.1016/j.molcel.2024.01.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 12/12/2023] [Accepted: 01/19/2024] [Indexed: 02/17/2024]
Abstract
The high incidence of whole-arm chromosome aneuploidy and translocations in tumors suggests instability of centromeres, unique loci built on repetitive sequences and essential for chromosome separation. The causes behind this fragility and the mechanisms preserving centromere integrity remain elusive. We show that replication stress, hallmark of pre-cancerous lesions, promotes centromeric breakage in mitosis, due to spindle forces and endonuclease activities. Mechanistically, we unveil unique dynamics of the centromeric replisome distinct from the rest of the genome. Locus-specific proteomics identifies specialized DNA replication and repair proteins at centromeres, highlighting them as difficult-to-replicate regions. The translesion synthesis pathway, along with other factors, acts to sustain centromere replication and integrity. Prolonged stress causes centromeric alterations like ruptures and translocations, as observed in ovarian cancer models experiencing replication stress. This study provides unprecedented insights into centromere replication and integrity, proposing mechanistic insights into the origins of centromere alterations leading to abnormal cancerous karyotypes.
Collapse
Affiliation(s)
- Andrea Scelfo
- Institut Curie, PSL Research University, Sorbonne Université, CNRS, UMR144, 26 rue d'Ulm, Paris 75005, France
| | - Annapaola Angrisani
- Institut Curie, PSL Research University, Sorbonne Université, CNRS, UMR144, 26 rue d'Ulm, Paris 75005, France
| | - Marco Grillo
- Institut Curie, PSL Research University, Sorbonne Université, CNRS, UMR144, 26 rue d'Ulm, Paris 75005, France
| | - Bethany M Barnes
- Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Cancer Research Centre, Wilmslow Road, Manchester M20 4GJ, UK
| | - Francesc Muyas
- European Molecular Biology Laboratory, European Bioinformatics Institute, Hinxton, Cambridge CB10 1SD, UK
| | - Carolin M Sauer
- European Molecular Biology Laboratory, European Bioinformatics Institute, Hinxton, Cambridge CB10 1SD, UK
| | | | - Marie Dumont
- Institut Curie, PSL Research University, Sorbonne Université, CNRS, UMR144, 26 rue d'Ulm, Paris 75005, France
| | - Marine Grison
- Institut Curie, PSL Research University, Sorbonne Université, CNRS, UMR144, 26 rue d'Ulm, Paris 75005, France
| | - David Mazaud
- Plateforme Imagerie PICT-IBiSA, Institut Curie, PSL Research University, Paris 75005, France; Institut Curie, PSL Research University, Sorbonne Université, CNRS, UMR3664, 26 rue d'Ulm, Paris 75005, France
| | - Mickaël Garnier
- Plateforme Imagerie PICT-IBiSA, Institut Curie, PSL Research University, Paris 75005, France; Institut Curie, PSL Research University, Sorbonne Université, CNRS, UMR3664, 26 rue d'Ulm, Paris 75005, France
| | - Laetitia Guintini
- Institute of Human Genetics, CNRS-Université de Montpellier, Montpellier 34396, France
| | - Louisa Nelson
- Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Cancer Research Centre, Wilmslow Road, Manchester M20 4GJ, UK
| | - Fumiko Esashi
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK
| | - Isidro Cortés-Ciriano
- European Molecular Biology Laboratory, European Bioinformatics Institute, Hinxton, Cambridge CB10 1SD, UK
| | - Stephen S Taylor
- Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Cancer Research Centre, Wilmslow Road, Manchester M20 4GJ, UK
| | - Jérôme Déjardin
- Institute of Human Genetics, CNRS-Université de Montpellier, Montpellier 34396, France
| | - Therese Wilhelm
- Institut Curie, PSL Research University, Sorbonne Université, CNRS, UMR144, 26 rue d'Ulm, Paris 75005, France; Institut Curie, PSL Research University, Sorbonne Université, CNRS, UMR3664, 26 rue d'Ulm, Paris 75005, France.
| | - Daniele Fachinetti
- Institut Curie, PSL Research University, Sorbonne Université, CNRS, UMR144, 26 rue d'Ulm, Paris 75005, France; Institut Curie, PSL Research University, Sorbonne Université, CNRS, UMR3664, 26 rue d'Ulm, Paris 75005, France.
| |
Collapse
|
8
|
Das A, Giri AK, Bhattacharjee P. Targeting 'histone mark': Advanced approaches in epigenetic regulation of telomere dynamics in cancer. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2024; 1867:195007. [PMID: 38237857 DOI: 10.1016/j.bbagrm.2024.195007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 01/09/2024] [Accepted: 01/10/2024] [Indexed: 01/23/2024]
Abstract
Telomere integrity is required for the maintenance of genome stability and prevention of oncogenic transformation of cells. Recent evidence suggests the presence of epigenetic modifications as an important regulator of mammalian telomeres. Telomeric and subtelomeric regions are rich in epigenetic marks that regulate telomere length majorly through DNA methylation and post-translational histone modifications. Specific histone modifying enzymes play an integral role in establishing telomeric histone codes necessary for the maintenance of structural integrity. Alterations of crucial histone moieties and histone modifiers cause deregulations in the telomeric chromatin leading to carcinogenic manifestations. This review delves into the significance of histone modifications and their influence on telomere dynamics concerning cancer. Additionally, it highlights the existing research gaps that hold the potential to drive the development of therapeutic interventions targeting the telomere epigenome.
Collapse
Affiliation(s)
- Ankita Das
- Department of Environmental Science, University of Calcutta, Kolkata 700019, India; Department of Zoology, University of Calcutta, Kolkata 700019, India
| | - Ashok K Giri
- Molecular Genetics Division, CSIR-Indian Institute of Chemical Biology, Kolkata 700032, India
| | - Pritha Bhattacharjee
- Department of Environmental Science, University of Calcutta, Kolkata 700019, India.
| |
Collapse
|
9
|
Olson CL, Wuttke DS. Guardians of the Genome: How the Single-Stranded DNA-Binding Proteins RPA and CST Facilitate Telomere Replication. Biomolecules 2024; 14:263. [PMID: 38540683 PMCID: PMC10968030 DOI: 10.3390/biom14030263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 02/02/2024] [Accepted: 02/20/2024] [Indexed: 04/26/2024] Open
Abstract
Telomeres act as the protective caps of eukaryotic linear chromosomes; thus, proper telomere maintenance is crucial for genome stability. Successful telomere replication is a cornerstone of telomere length regulation, but this process can be fraught due to the many intrinsic challenges telomeres pose to the replication machinery. In addition to the famous "end replication" problem due to the discontinuous nature of lagging strand synthesis, telomeres require various telomere-specific steps for maintaining the proper 3' overhang length. Bulk telomere replication also encounters its own difficulties as telomeres are prone to various forms of replication roadblocks. These roadblocks can result in an increase in replication stress that can cause replication forks to slow, stall, or become reversed. Ultimately, this leads to excess single-stranded DNA (ssDNA) that needs to be managed and protected for replication to continue and to prevent DNA damage and genome instability. RPA and CST are single-stranded DNA-binding protein complexes that play key roles in performing this task and help stabilize stalled forks for continued replication. The interplay between RPA and CST, their functions at telomeres during replication, and their specialized features for helping overcome replication stress at telomeres are the focus of this review.
Collapse
Affiliation(s)
- Conner L. Olson
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Deborah S. Wuttke
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80309, USA
| |
Collapse
|
10
|
Musmaker K, Wells J, Tsai MC, Comeron JM, Malkova A. Alternative Lengthening of Telomeres in Yeast: Old Questions and New Approaches. Biomolecules 2024; 14:113. [PMID: 38254712 PMCID: PMC10813009 DOI: 10.3390/biom14010113] [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: 12/14/2023] [Revised: 01/11/2024] [Accepted: 01/12/2024] [Indexed: 01/24/2024] Open
Abstract
Alternative lengthening of telomeres (ALT) is a homologous recombination-based pathway utilized by 10-15% of cancer cells that allows cells to maintain their telomeres in the absence of telomerase. This pathway was originally discovered in the yeast Saccharomyces cerevisiae and, for decades, yeast has served as a robust model to study ALT. Using yeast as a model, two types of ALT (RAD51-dependent and RAD51-independent) have been described. Studies in yeast have provided the phenotypic characterization of ALT survivors, descriptions of the proteins involved, and implicated break-induced replication (BIR) as the mechanism responsible for ALT. Nevertheless, many questions have remained, and answering them has required the development of new quantitative methods. In this review we discuss the historic aspects of the ALT investigation in yeast as well as new approaches to investigating ALT, including ultra-long sequencing, computational modeling, and the use of population genetics. We discuss how employing new methods contributes to our current understanding of the ALT mechanism and how they may expand our understanding of ALT in the future.
Collapse
Affiliation(s)
- Kendra Musmaker
- Department of Biology, University of Iowa, Iowa City, IA 52242, USA (J.W.)
| | - Jacob Wells
- Department of Biology, University of Iowa, Iowa City, IA 52242, USA (J.W.)
| | - Meng-Chia Tsai
- Department of Biology, University of Iowa, Iowa City, IA 52242, USA (J.W.)
| | - Josep M. Comeron
- Department of Biology, University of Iowa, Iowa City, IA 52242, USA (J.W.)
- Interdisciplinary Graduate Program in Genetics, University of Iowa, Iowa City, IA 52242, USA
| | - Anna Malkova
- Department of Biology, University of Iowa, Iowa City, IA 52242, USA (J.W.)
- Interdisciplinary Graduate Program in Genetics, University of Iowa, Iowa City, IA 52242, USA
| |
Collapse
|
11
|
Li B. Unwrap RAP1's Mystery at Kinetoplastid Telomeres. Biomolecules 2024; 14:67. [PMID: 38254667 PMCID: PMC10813129 DOI: 10.3390/biom14010067] [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: 12/06/2023] [Revised: 12/27/2023] [Accepted: 12/27/2023] [Indexed: 01/24/2024] Open
Abstract
Although located at the chromosome end, telomeres are an essential chromosome component that helps maintain genome integrity and chromosome stability from protozoa to mammals. The role of telomere proteins in chromosome end protection is conserved, where they suppress various DNA damage response machineries and block nucleolytic degradation of the natural chromosome ends, although the detailed underlying mechanisms are not identical. In addition, the specialized telomere structure exerts a repressive epigenetic effect on expression of genes located at subtelomeres in a number of eukaryotic organisms. This so-called telomeric silencing also affects virulence of a number of microbial pathogens that undergo antigenic variation/phenotypic switching. Telomere proteins, particularly the RAP1 homologs, have been shown to be a key player for telomeric silencing. RAP1 homologs also suppress the expression of Telomere Repeat-containing RNA (TERRA), which is linked to their roles in telomere stability maintenance. The functions of RAP1s in suppressing telomere recombination are largely conserved from kinetoplastids to mammals. However, the underlying mechanisms of RAP1-mediated telomeric silencing have many species-specific features. In this review, I will focus on Trypanosoma brucei RAP1's functions in suppressing telomeric/subtelomeric DNA recombination and in the regulation of monoallelic expression of subtelomere-located major surface antigen genes. Common and unique mechanisms will be compared among RAP1 homologs, and their implications will be discussed.
Collapse
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, 2121 Euclid Avenue, Cleveland, OH 44115, USA;
- Case Comprehensive Cancer Center, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH 44195, USA
- Center for RNA Science and Therapeutics, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| |
Collapse
|
12
|
Xu Y, Komiyama M. G-Quadruplexes in Human Telomere: Structures, Properties, and Applications. Molecules 2023; 29:174. [PMID: 38202757 PMCID: PMC10780218 DOI: 10.3390/molecules29010174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 12/20/2023] [Accepted: 12/25/2023] [Indexed: 01/12/2024] Open
Abstract
G-quadruplexes, intricate four-stranded structures composed of G-tetrads formed by four guanine bases, are prevalent in both DNA and RNA. Notably, these structures play pivotal roles in human telomeres, contributing to essential cellular functions. Additionally, the existence of DNA:RNA hybrid G-quadruplexes adds a layer of complexity to their structural diversity. This review provides a comprehensive overview of recent advancements in unraveling the intricacies of DNA and RNA G-quadruplexes within human telomeres. Detailed insights into their structural features are presented, encompassing the latest developments in chemical approaches designed to probe these G-quadruplex structures. Furthermore, this review explores the applications of G-quadruplex structures in targeting human telomeres. Finally, the manuscript outlines the imminent challenges in this evolving field, setting the stage for future investigations.
Collapse
Affiliation(s)
- Yan Xu
- Division of Chemistry, Department of Medical Sciences, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki 889-1692, Japan
| | - Makoto Komiyama
- Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8904, Japan
| |
Collapse
|
13
|
Wang Y, Zhu W, Jang Y, Sommers JA, Yi G, Puligilla C, Croteau DL, Yang Y, Kai M, Liu Y. The RNA-binding motif protein 14 regulates telomere integrity at the interface of TERRA and telomeric R-loops. Nucleic Acids Res 2023; 51:12242-12260. [PMID: 37930826 PMCID: PMC10711441 DOI: 10.1093/nar/gkad967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 10/13/2023] [Indexed: 11/08/2023] Open
Abstract
Telomeric repeat-containing RNA (TERRA) and its formation of RNA:DNA hybrids (or TERRA R-loops), influence telomere maintenance, particularly in human cancer cells that use homologous recombination-mediated alternative lengthening of telomeres. Here, we report that the RNA-binding motif protein 14 (RBM14) is associated with telomeres in human cancer cells. RBM14 negatively regulates TERRA expression. It also binds to TERRA and inhibits it from forming TERRA R-loops at telomeres. RBM14 depletion has several effects, including elevated TERRA levels, telomeric R-loops, telomere dysfunction-induced DNA damage foci formation, particularly in the presence of DNA replication stress, pRPA32 accumulation at telomeres and telomere signal-free ends. Thus, RBM14 protects telomere integrity via modulating TERRA levels and its R-loop formation at telomeres.
Collapse
Affiliation(s)
- Yajun Wang
- Laboratory of Genetics and Genomics, 251 Bayview Blvd, National Institute on Aging/National Institutes of Health, Baltimore, MD 21224, USA
- Blood Cell Development and Function Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Wei Zhu
- Laboratory of Genetics and Genomics, 251 Bayview Blvd, National Institute on Aging/National Institutes of Health, Baltimore, MD 21224, USA
| | - Yumi Jang
- Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Joshua A Sommers
- Translational Gerontology Branch, 251 Bayview Blvd, National Institute on Aging/National Institutes of Health, Baltimore, MD 21224, USA
| | - Gong Yi
- Laboratory of Genetics and Genomics, 251 Bayview Blvd, National Institute on Aging/National Institutes of Health, Baltimore, MD 21224, USA
| | - Chandrakala Puligilla
- Laboratory of Genetics and Genomics, 251 Bayview Blvd, National Institute on Aging/National Institutes of Health, Baltimore, MD 21224, USA
| | - Deborah L Croteau
- Laboratory of Genetics and Genomics, 251 Bayview Blvd, National Institute on Aging/National Institutes of Health, Baltimore, MD 21224, USA
| | - Yibin Yang
- Blood Cell Development and Function Program, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Mihoko Kai
- Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Yie Liu
- Laboratory of Genetics and Genomics, 251 Bayview Blvd, National Institute on Aging/National Institutes of Health, Baltimore, MD 21224, USA
| |
Collapse
|
14
|
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.
Collapse
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
| |
Collapse
|
15
|
Agabekian IA, Abdulkina LR, Lushnenko AY, Young PG, Valeeva LR, Boskovic O, Lilly EG, Sharipova MR, Shippen DE, Juenger TE, Shakirov EV. Arabidopsis AN3 and OLIGOCELLULA genes link telomere maintenance mechanisms with cell division and expansion control. RESEARCH SQUARE 2023:rs.3.rs-3438810. [PMID: 37961382 PMCID: PMC10635316 DOI: 10.21203/rs.3.rs-3438810/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Telomeres are conserved chromosomal structures necessary for continued cell division and proliferation. In addition to the classical telomerase pathway, multiple other genes including those involved in ribosome metabolism and chromatin modification contribute to telomere length maintenance. We previously reported that Arabidopsis thaliana ribosome biogenesis genes OLI2/NOP2A, OLI5/RPL5A and OLI7/RPL5B have critical roles in telomere length regulation. These three OLIGOCELLULA genes were also shown to function in cell proliferation and expansion control and to genetically interact with the transcriptional co-activator ANGUSTIFOLIA3 (AN3). Here we show that AN3-deficient plants progressively lose telomeric DNA in early homozygous mutant generations, but ultimately establish a new shorter telomere length setpoint by the fifth mutant generation with a telomere length similar to oli2/nop2a - deficient plants. Analysis of double an3 oli2 mutants indicates that the two genes are epistatic for telomere length control. Telomere shortening in an3 and oli mutants is not caused by telomerase inhibition; wild type levels of telomerase activity are detected in all analyzed mutants in vitro. Late generations of an3 and oli mutants are prone to stem cell damage in the root apical meristem, implying that genes regulating telomere length may have conserved functional roles in stem cell maintenance mechanisms. Multiple instances of anaphase fusions in late generations of oli5 and oli7 mutants were observed, highlighting an unexpected effect of ribosome biogenesis factors on chromosome integrity. Overall, our data implicate AN3 transcription coactivator and OLIGOCELLULA proteins in the establishment of telomere length set point in plants and further suggest that multiple regulators with pleiotropic functions can connect telomere biology with cell proliferation and cell expansion pathways.
Collapse
Affiliation(s)
- Inna A Agabekian
- Kazan Federal University: Kazanskij Privolzskij federal'nyj universitet
| | | | - Alina Y Lushnenko
- Kazan Federal University: Kazanskij Privolzskij federal'nyj universitet
| | | | | | | | | | | | | | | | | |
Collapse
|
16
|
He Q, Lim CJ. Models for human telomere C-strand fill-in by CST-Polα-primase. Trends Biochem Sci 2023; 48:860-872. [PMID: 37586999 PMCID: PMC10528720 DOI: 10.1016/j.tibs.2023.07.008] [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: 04/30/2023] [Revised: 07/12/2023] [Accepted: 07/18/2023] [Indexed: 08/18/2023]
Abstract
Telomere maintenance is essential for the genome integrity of eukaryotes, and this function is underpinned by the two-step telomeric DNA synthesis process: telomere G-overhang extension by telomerase and complementary strand fill-in by DNA polymerase alpha-primase (polα-primase). Compared to the telomerase step, the telomere C-strand fill-in mechanism is less understood. Recent studies have provided new insights into how telomeric single-stranded DNA-binding protein CTC1-STN1-TEN1 (CST) and polα-primase coordinate to synthesize the telomeric C-strand for telomere overhang fill-in. Cryogenic electron microscopy (cryo-EM) structures of CST-polα-primase complexes have provided additional insights into how they assemble at telomeric templates and de novo synthesize the telomere C-strand. In this review, we discuss how these latest findings coalesce with existing understanding to develop a human telomere C-strand fill-in mechanism model.
Collapse
Affiliation(s)
- Qixiang He
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - Ci Ji Lim
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA.
| |
Collapse
|
17
|
Nonaka K, Takubo K, Aida J, Watai Y, Komatsu A, Gomi F, Shichi Y, Yamazaki Y, Ishiwata T, Sasano H, Arai T. Accelerated telomere shortening in adrenal zona reticularis in patients with prolonged critical illness. Front Endocrinol (Lausanne) 2023; 14:1244553. [PMID: 37745694 PMCID: PMC10512174 DOI: 10.3389/fendo.2023.1244553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 08/18/2023] [Indexed: 09/26/2023] Open
Abstract
Background The number of patients with prolonged critical illness (PCI) has been increasing in many countries, and the adrenal gland plays an important role in maintaining homeostasis during PCI. Chronic disease burden is reportedly associated with shorter telomere lengths in human tissues. Telomere shortening in human somatic cells is largely dependent on cell divisions, and critically short telomeres lead to cellular dysfunction and aging. However, the association between PCI and telomere lengths in human adrenal cells is poorly understood. In this study, we investigated this association to assess whether the burden of PCI could accelerate the aging process in adrenal cells. Methods Adrenocortical tissues from patients who died after PCI usually show a diffuse pattern of intracellular cholesterol ester depletion (i.e., lipid depletion). This study examined near-normal adrenal glands obtained from autopsied patients who died suddenly (control group) and lipid-depleted adrenal glands obtained from autopsied patients who died after PCI (PCI group). The control group included 7 men aged 80 to 94 years (mean age: 85.3 years) and 7 women aged 84 to 94 years (mean age: 87.7 years). The PCI group included 10 men aged 71 to 88 years (mean age: 78.8 years) and 8 women aged 77 to 95 years (mean age: 85.6 years). By using quantitative fluorescence in situ hybridization, relative telomere lengths (RTLs) were determined in the parenchymal cells of the three adrenocortical zones (zona glomerulosa, zona fasciculata, and zona reticularis [ZR]) and in the chromaffin cells of the medulla. The number of adrenal parenchymal cells was determined by immunohistochemistry and digital image analysis. Results RTLs in ZR cells were significantly shorter in the PCI group than in the control group for both men and women (P = 0.0001 for men and P = 0.0012 for women). However, RTLs in the remaining three types of adrenal cells did not differ between the control and PCI groups for both men and women. The number of ZR cells was higher in the PCI group than in the control group for both men and women (P < 0.0001 for both men and women). The proportion of the number of ZR cells to the total number of adrenocortical parenchymal cells was also higher in the PCI group than in the control group (P < 0.0001 for both men and women). The Ki-67 proliferation index in ZR cells was higher in the PCI group than in the control group (P = 0.0039 for men and P = 0.0063 for women). Conclusions This study demonstrated ZR cell-specific telomere shortening in patients with adrenal lipid depletion who died after PCI. Our results suggest that the reactive proliferation of ZR cells accelerates the telomere shortening and aging process in ZR cells in these patients. The results of our study may contribute to the understanding of adrenal aging during PCI.
Collapse
Affiliation(s)
- Keisuke Nonaka
- Division of Aging and Carcinogenesis, Research Team for Geriatric Pathology, Tokyo Metropolitan Institute for Geriatrics and Gerontology, Tokyo, Japan
| | - Kaiyo Takubo
- Division of Aging and Carcinogenesis, Research Team for Geriatric Pathology, Tokyo Metropolitan Institute for Geriatrics and Gerontology, Tokyo, Japan
| | - Junko Aida
- Division of Aging and Carcinogenesis, Research Team for Geriatric Pathology, Tokyo Metropolitan Institute for Geriatrics and Gerontology, Tokyo, Japan
| | - Yoriko Watai
- Department of Drug Discovery Support Business, Summit Pharmaceuticals International, Tokyo, Japan
| | - Akiko Komatsu
- Department of Pathology, Tokyo Metropolitan Institute for Geriatrics and Gerontology, Tokyo, Japan
| | - Fujiya Gomi
- Division of Aging and Carcinogenesis, Research Team for Geriatric Pathology, Tokyo Metropolitan Institute for Geriatrics and Gerontology, Tokyo, Japan
| | - Yuuki Shichi
- Division of Aging and Carcinogenesis, Research Team for Geriatric Pathology, Tokyo Metropolitan Institute for Geriatrics and Gerontology, Tokyo, Japan
| | - Yuto Yamazaki
- Department of Pathology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Toshiyuki Ishiwata
- Division of Aging and Carcinogenesis, Research Team for Geriatric Pathology, Tokyo Metropolitan Institute for Geriatrics and Gerontology, Tokyo, Japan
| | - Hironobu Sasano
- Department of Pathology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Tomio Arai
- Department of Pathology, Tokyo Metropolitan Institute for Geriatrics and Gerontology, Tokyo, Japan
| |
Collapse
|
18
|
Singh P, Gazy I, Kupiec M. Control of telomere length in yeast by SUMOylated PCNA and the Elg1 PCNA unloader. eLife 2023; 12:RP86990. [PMID: 37530521 PMCID: PMC10396338 DOI: 10.7554/elife.86990] [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] [Indexed: 08/03/2023] Open
Abstract
Telomeres cap and protect the linear eukaryotic chromosomes. Telomere length is determined by an equilibrium between positive and negative regulators of telomerase activity. A systematic screen for yeast mutants that affect telomere length maintenance in the yeast Saccharomyces cerevisiae revealed that mutations in any of ~500 genes affects telomere length. One of the genes that, when mutated, causes telomere elongation is ELG1, which encodes an unloader of PCNA, the processivity factor for replicative DNA polymerases. PCNA can undergo SUMOylation on two conserved residues, K164 and K127, or ubiquitination at lysine 164. These modifications have already been implicated in genome stability processes. We report that SUMOylated PCNA acts as a signal that positively regulates telomerase activity. We also uncovered physical interactions between Elg1 and the CST (Cdc13-Stn1-Ten) complex and addressed the mechanism by which Elg1 and Stn1 negatively regulates telomere elongation, coordinated by SUMO. We discuss these results with respect to how chromosomal replication and telomere elongation are coordinated.
Collapse
Affiliation(s)
- Pragyan Singh
- The Shmunis School of Biomedicine and Cancer Research, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Inbal Gazy
- The Shmunis School of Biomedicine and Cancer Research, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Martin Kupiec
- The Shmunis School of Biomedicine and Cancer Research, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| |
Collapse
|
19
|
Hieber C, Grabbe S, Bros M. Counteracting Immunosenescence-Which Therapeutic Strategies Are Promising? Biomolecules 2023; 13:1085. [PMID: 37509121 PMCID: PMC10377144 DOI: 10.3390/biom13071085] [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: 05/02/2023] [Revised: 07/03/2023] [Accepted: 07/05/2023] [Indexed: 07/30/2023] Open
Abstract
Aging attenuates the overall responsiveness of the immune system to eradicate pathogens. The increased production of pro-inflammatory cytokines by innate immune cells under basal conditions, termed inflammaging, contributes to impaired innate immune responsiveness towards pathogen-mediated stimulation and limits antigen-presenting activity. Adaptive immune responses are attenuated as well due to lowered numbers of naïve lymphocytes and their impaired responsiveness towards antigen-specific stimulation. Additionally, the numbers of immunoregulatory cell types, comprising regulatory T cells and myeloid-derived suppressor cells, that inhibit the activity of innate and adaptive immune cells are elevated. This review aims to summarize our knowledge on the cellular and molecular causes of immunosenescence while also taking into account senescence effects that constitute immune evasion mechanisms in the case of chronic viral infections and cancer. For tumor therapy numerous nanoformulated drugs have been developed to overcome poor solubility of compounds and to enable cell-directed delivery in order to restore immune functions, e.g., by addressing dysregulated signaling pathways. Further, nanovaccines which efficiently address antigen-presenting cells to mount sustained anti-tumor immune responses have been clinically evaluated. Further, senolytics that selectively deplete senescent cells are being tested in a number of clinical trials. Here we discuss the potential use of such drugs to improve anti-aging therapy.
Collapse
Affiliation(s)
- Christoph Hieber
- Department of Dermatology, University Medical Center of the Johannes Gutenberg-University Mainz, Langenbeckstraße 1, 55131 Mainz, Germany
- Institute of Molecular Biology (IMB), Ackermannweg 4, 55128 Mainz, Germany
| | - Stephan Grabbe
- Department of Dermatology, University Medical Center of the Johannes Gutenberg-University Mainz, Langenbeckstraße 1, 55131 Mainz, Germany
- Institute of Molecular Biology (IMB), Ackermannweg 4, 55128 Mainz, Germany
| | - Matthias Bros
- Department of Dermatology, University Medical Center of the Johannes Gutenberg-University Mainz, Langenbeckstraße 1, 55131 Mainz, Germany
| |
Collapse
|
20
|
Lue NF, Autexier C. Orchestrating nucleic acid-protein interactions at chromosome ends: telomerase mechanisms come into focus. Nat Struct Mol Biol 2023; 30:878-890. [PMID: 37400652 PMCID: PMC10539978 DOI: 10.1038/s41594-023-01022-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Accepted: 05/16/2023] [Indexed: 07/05/2023]
Abstract
Telomerase is a special reverse transcriptase ribonucleoprotein dedicated to the synthesis of telomere repeats that protect chromosome ends. Among reverse transcriptases, telomerase is unique in using a stably associated RNA with an embedded template to synthesize a specified sequence. Moreover, it is capable of iteratively copying the same template region (repeat addition processivity) through multiple rounds of RNA-DNA unpairing and reannealing, that is, the translocation reaction. Biochemical analyses of telomerase over the past 3 decades in protozoa, fungi and mammals have identified structural elements that underpin telomerase mechanisms and have led to models that account for the special attributes of telomerase. Notably, these findings and models can now be interpreted and adjudicated through recent cryo-EM structures of Tetrahymena and human telomerase holoenzyme complexes in association with substrates and regulatory proteins. Collectively, these structures reveal the intricate protein-nucleic acid interactions that potentiate telomerase's unique translocation reaction and clarify how this enzyme reconfigures the basic reverse transcriptase scaffold to craft a polymerase dedicated to the synthesis of telomere DNA. Among the many new insights is the resolution of the telomerase 'anchor site' proposed more than 3 decades ago. The structures also highlight the nearly universal conservation of a protein-protein interface between an oligonucleotide/oligosaccharide-binding (OB)-fold regulatory protein and the telomerase catalytic subunit, which enables spatial and temporal regulation of telomerase function in vivo. In this Review, we discuss key features of the structures in combination with relevant functional analyses. We also examine conserved and divergent aspects of telomerase mechanisms as gleaned from studies in different model organisms.
Collapse
Affiliation(s)
- Neal F Lue
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, NY, USA.
| | - Chantal Autexier
- Lady Davis Institute for Medical Research, Jewish General Hospital and Department of Anatomy and Cell Biology and Department of Medicine, McGill University, Montreal, Quebec, Canada.
| |
Collapse
|
21
|
Kroupa M, Kubecek O, Tomasova K, Hanak P, Krupova M, Cervena K, Siskova A, Rosendorf J, Hosek P, Vodickova L, Vodicka P, Liska V, John S, Vymetalkova V, Petera J. The dynamics of telomere length in primary and metastatic colorectal cancer lesions. Sci Rep 2023; 13:9097. [PMID: 37277368 DOI: 10.1038/s41598-023-35835-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 05/24/2023] [Indexed: 06/07/2023] Open
Abstract
Telomeric sequences, the structures comprised of hexanucleotide repeats and associated proteins, play a pivotal role in chromosome end protection and preservation of genomic stability. Herein we address telomere length (TL) dynamics in primary colorectal cancer (CRC) tumour tissues and corresponding liver metastases. TL was measured by multiplex monochrome real-time qPCR in paired samples of primary tumours and liver metastases along with non-cancerous reference tissues obtained from 51 patients diagnosed with metastatic CRC. Telomere shortening was observed in the majority of primary tumour tissues compared to non-cancerous mucosa (84.1%, p < 0.0001). Tumours located within the proximal colon had shorter TL than those in the rectum (p < 0.05). TL in liver metastases was not significantly different from that in primary tumours (p = 0.41). TL in metastatic tissue was shorter in the patients diagnosed with metachronous liver metastases than in those diagnosed with synchronous liver metastases (p = 0.03). The metastatic liver lesions size correlated with the TL in metastases (p < 0.05). Following the neoadjuvant treatment, the patients with rectal cancer had shortened telomeres in tumour tissue than prior to the therapy (p = 0.01). Patients with a TL ratio between tumour tissue and the adjacent non-cancerous mucosa of ≥ 0.387 were associated with increased overall survival (p = 0.01). This study provides insights into TL dynamics during progression of the disease. The results show TL differences in metastatic lesions and may help in clinical practice to predict the patient's prognosis.
Collapse
Affiliation(s)
- Michal Kroupa
- Department of Molecular Biology of Cancer, Institute of Experimental Medicine of the Czech Academy of Sciences, Videnska 1083, 142 20, Prague, Czech Republic.
- Biomedical Centre, Faculty of Medicine in Pilsen Charles University, Alej Svobody 76, 323 00, Pilsen, Czech Republic.
| | - Ondrej Kubecek
- Department of Oncology and Radiotherapy, Charles University, Medical Faculty and University Hospital in Hradec Kralove, Simkova 870, 500 38, Hradec Kralove, Czech Republic
| | - Kristyna Tomasova
- Department of Molecular Biology of Cancer, Institute of Experimental Medicine of the Czech Academy of Sciences, Videnska 1083, 142 20, Prague, Czech Republic
- Biomedical Centre, Faculty of Medicine in Pilsen Charles University, Alej Svobody 76, 323 00, Pilsen, Czech Republic
| | - Petr Hanak
- Department of Molecular Biology of Cancer, Institute of Experimental Medicine of the Czech Academy of Sciences, Videnska 1083, 142 20, Prague, Czech Republic
| | - Marketa Krupova
- The Fingerland Department of Pathology, University Hospital in Hradec Kralove, Sokolska 581, 50005, Hradec Kralove, Czech Republic
| | - Klara Cervena
- Department of Molecular Biology of Cancer, Institute of Experimental Medicine of the Czech Academy of Sciences, Videnska 1083, 142 20, Prague, Czech Republic
- Institute of Biology and Medical Genetics, 1St Faculty of Medicine, Charles University, Albertov 4, 128 00, Prague, Czech Republic
| | - Anna Siskova
- Department of Molecular Biology of Cancer, Institute of Experimental Medicine of the Czech Academy of Sciences, Videnska 1083, 142 20, Prague, Czech Republic
- Institute of Biology and Medical Genetics, 1St Faculty of Medicine, Charles University, Albertov 4, 128 00, Prague, Czech Republic
| | - Jachym Rosendorf
- Department of Molecular Biology of Cancer, Institute of Experimental Medicine of the Czech Academy of Sciences, Videnska 1083, 142 20, Prague, Czech Republic
- Biomedical Centre, Faculty of Medicine in Pilsen Charles University, Alej Svobody 76, 323 00, Pilsen, Czech Republic
| | - Petr Hosek
- Biomedical Centre, Faculty of Medicine in Pilsen Charles University, Alej Svobody 76, 323 00, Pilsen, Czech Republic
| | - Ludmila Vodickova
- Department of Molecular Biology of Cancer, Institute of Experimental Medicine of the Czech Academy of Sciences, Videnska 1083, 142 20, Prague, Czech Republic
- Biomedical Centre, Faculty of Medicine in Pilsen Charles University, Alej Svobody 76, 323 00, Pilsen, Czech Republic
- Institute of Biology and Medical Genetics, 1St Faculty of Medicine, Charles University, Albertov 4, 128 00, Prague, Czech Republic
| | - Pavel Vodicka
- Department of Molecular Biology of Cancer, Institute of Experimental Medicine of the Czech Academy of Sciences, Videnska 1083, 142 20, Prague, Czech Republic
- Biomedical Centre, Faculty of Medicine in Pilsen Charles University, Alej Svobody 76, 323 00, Pilsen, Czech Republic
- Institute of Biology and Medical Genetics, 1St Faculty of Medicine, Charles University, Albertov 4, 128 00, Prague, Czech Republic
| | - Vaclav Liska
- Department of Molecular Biology of Cancer, Institute of Experimental Medicine of the Czech Academy of Sciences, Videnska 1083, 142 20, Prague, Czech Republic
- Biomedical Centre, Faculty of Medicine in Pilsen Charles University, Alej Svobody 76, 323 00, Pilsen, Czech Republic
| | - Stanislav John
- Department of Oncology and Radiotherapy, Charles University, Medical Faculty and University Hospital in Hradec Kralove, Simkova 870, 500 38, Hradec Kralove, Czech Republic
| | - Veronika Vymetalkova
- Department of Molecular Biology of Cancer, Institute of Experimental Medicine of the Czech Academy of Sciences, Videnska 1083, 142 20, Prague, Czech Republic
- Biomedical Centre, Faculty of Medicine in Pilsen Charles University, Alej Svobody 76, 323 00, Pilsen, Czech Republic
- Institute of Biology and Medical Genetics, 1St Faculty of Medicine, Charles University, Albertov 4, 128 00, Prague, Czech Republic
| | - Jiri Petera
- Department of Oncology and Radiotherapy, Charles University, Medical Faculty and University Hospital in Hradec Kralove, Simkova 870, 500 38, Hradec Kralove, Czech Republic
| |
Collapse
|
22
|
Ngo K, Gittens TH, Gonzalez DI, Hatmaker EA, Plotkin S, Engle M, Friedman GA, Goldin M, Hoerr RE, Eichman BF, Rokas A, Benton ML, Friedman KL. A comprehensive map of hotspots of de novo telomere addition in Saccharomyces cerevisiae. Genetics 2023; 224:iyad076. [PMID: 37119805 PMCID: PMC10474931 DOI: 10.1093/genetics/iyad076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 04/15/2023] [Accepted: 04/18/2023] [Indexed: 05/01/2023] Open
Abstract
Telomere healing occurs when telomerase, normally restricted to chromosome ends, acts upon a double-strand break to create a new, functional telomere. De novo telomere addition (dnTA) on the centromere-proximal side of a break truncates the chromosome but, by blocking resection, may allow the cell to survive an otherwise lethal event. We previously identified several sequences in the baker's yeast, Saccharomyces cerevisiae, that act as hotspots of dnTA [termed Sites of Repair-associated Telomere Addition (SiRTAs)], but the distribution and functional relevance of SiRTAs is unclear. Here, we describe a high-throughput sequencing method to measure the frequency and location of telomere addition within sequences of interest. Combining this methodology with a computational algorithm that identifies SiRTA sequence motifs, we generate the first comprehensive map of telomere-addition hotspots in yeast. Putative SiRTAs are strongly enriched in subtelomeric regions where they may facilitate formation of a new telomere following catastrophic telomere loss. In contrast, outside of subtelomeres, the distribution and orientation of SiRTAs appears random. Since truncating the chromosome at most SiRTAs would be lethal, this observation argues against selection for these sequences as sites of telomere addition per se. We find, however, that sequences predicted to function as SiRTAs are significantly more prevalent across the genome than expected by chance. Sequences identified by the algorithm bind the telomeric protein Cdc13, raising the possibility that association of Cdc13 with single-stranded regions generated during the response to DNA damage may facilitate DNA repair more generally.
Collapse
Affiliation(s)
- Katrina Ngo
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232 USA
| | - Tristen H Gittens
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232 USA
| | - David I Gonzalez
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232 USA
| | - E Anne Hatmaker
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232 USA
- Evolutionary Studies Initiative, Vanderbilt University, Nashville, TN 37232 USA
| | - Simcha Plotkin
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232 USA
| | - Mason Engle
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232 USA
| | - Geofrey A Friedman
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232 USA
| | - Melissa Goldin
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232 USA
| | - Remington E Hoerr
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232 USA
| | - Brandt F Eichman
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232 USA
- Department of Biochemistry, Vanderbilt University, Nashville, TN 37232 USA
| | - Antonis Rokas
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232 USA
- Evolutionary Studies Initiative, Vanderbilt University, Nashville, TN 37232 USA
| | | | - Katherine L Friedman
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232 USA
| |
Collapse
|
23
|
Palamarchuk AI, Kovalenko EI, Streltsova MA. Multiple Actions of Telomerase Reverse Transcriptase in Cell Death Regulation. Biomedicines 2023; 11:biomedicines11041091. [PMID: 37189709 DOI: 10.3390/biomedicines11041091] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 03/25/2023] [Accepted: 04/02/2023] [Indexed: 04/07/2023] Open
Abstract
Telomerase reverse transcriptase (TERT), a core part of telomerase, has been known for a long time only for its telomere lengthening function by reverse transcription of RNA template. Currently, TERT is considered as an intriguing link between multiple signaling pathways. The diverse intracellular localization of TERT corresponds to a wide range of functional activities. In addition to the canonical function of protecting chromosome ends, TERT by itself or as a part of the telomerase complex participates in cell stress responses, gene regulation and mitochondria functioning. Upregulation of TERT expression and increased telomerase activity in cancer and somatic cells relate to improved survival and persistence of such cells. In this review, we summarize the data for a comprehensive understanding of the role of TERT in cell death regulation, with a focus on the interaction of TERT with signaling pathways involved in cell survival and stress response.
Collapse
Affiliation(s)
- Anastasia I. Palamarchuk
- Shemyakin & Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Ul. Miklukho-Maklaya 16/10, 117997 Moscow, Russia
| | - Elena I. Kovalenko
- Shemyakin & Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Ul. Miklukho-Maklaya 16/10, 117997 Moscow, Russia
| | - Maria A. Streltsova
- Shemyakin & Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Ul. Miklukho-Maklaya 16/10, 117997 Moscow, Russia
| |
Collapse
|
24
|
Pennarun G, Picotto J, Bertrand P. Close Ties between the Nuclear Envelope and Mammalian Telomeres: Give Me Shelter. Genes (Basel) 2023; 14:genes14040775. [PMID: 37107534 PMCID: PMC10137478 DOI: 10.3390/genes14040775] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 03/18/2023] [Accepted: 03/20/2023] [Indexed: 04/29/2023] Open
Abstract
The nuclear envelope (NE) in eukaryotic cells is essential to provide a protective compartment for the genome. Beside its role in connecting the nucleus with the cytoplasm, the NE has numerous important functions including chromatin organization, DNA replication and repair. NE alterations have been linked to different human diseases, such as laminopathies, and are a hallmark of cancer cells. Telomeres, the ends of eukaryotic chromosomes, are crucial for preserving genome stability. Their maintenance involves specific telomeric proteins, repair proteins and several additional factors, including NE proteins. Links between telomere maintenance and the NE have been well established in yeast, in which telomere tethering to the NE is critical for their preservation and beyond. For a long time, in mammalian cells, except during meiosis, telomeres were thought to be randomly localized throughout the nucleus, but recent advances have uncovered close ties between mammalian telomeres and the NE that play important roles for maintaining genome integrity. In this review, we will summarize these connections, with a special focus on telomere dynamics and the nuclear lamina, one of the main NE components, and discuss the evolutionary conservation of these mechanisms.
Collapse
Affiliation(s)
- Gaëlle Pennarun
- Université Paris Cité, INSERM, CEA, Stabilité Génétique Cellules Souches et Radiations, LREV/iRCM/IBFJ, F-92260 Fontenay-aux-Roses, France
- Université Paris-Saclay, INSERM, CEA, Stabilité Génétique Cellules Souches et Radiations, LREV/iRCM/IBFJ, F-92260 Fontenay-aux-Roses, France
| | - Julien Picotto
- Université Paris Cité, INSERM, CEA, Stabilité Génétique Cellules Souches et Radiations, LREV/iRCM/IBFJ, F-92260 Fontenay-aux-Roses, France
- Université Paris-Saclay, INSERM, CEA, Stabilité Génétique Cellules Souches et Radiations, LREV/iRCM/IBFJ, F-92260 Fontenay-aux-Roses, France
| | - Pascale Bertrand
- Université Paris Cité, INSERM, CEA, Stabilité Génétique Cellules Souches et Radiations, LREV/iRCM/IBFJ, F-92260 Fontenay-aux-Roses, France
- Université Paris-Saclay, INSERM, CEA, Stabilité Génétique Cellules Souches et Radiations, LREV/iRCM/IBFJ, F-92260 Fontenay-aux-Roses, France
| |
Collapse
|
25
|
Ngo K, Gittens TH, Gonzalez DI, Hatmaker EA, Plotkin S, Engle M, Friedman GA, Goldin M, Hoerr RE, Eichman BF, Rokas A, Benton ML, Friedman KL. A comprehensive map of hotspots of de novo telomere addition in Saccharomyces cerevisiae. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.20.533556. [PMID: 36993206 PMCID: PMC10055226 DOI: 10.1101/2023.03.20.533556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Telomere healing occurs when telomerase, normally restricted to chromosome ends, acts upon a double-strand break to create a new, functional telomere. De novo telomere addition on the centromere-proximal side of a break truncates the chromosome but, by blocking resection, may allow the cell to survive an otherwise lethal event. We previously identified several sequences in the baker’s yeast, Saccharomyces cerevisiae , that act as hotspots of de novo telomere addition (termed Sites of Repair-associated Telomere Addition or SiRTAs), but the distribution and functional relevance of SiRTAs is unclear. Here, we describe a high-throughput sequencing method to measure the frequency and location of telomere addition within sequences of interest. Combining this methodology with a computational algorithm that identifies SiRTA sequence motifs, we generate the first comprehensive map of telomere-addition hotspots in yeast. Putative SiRTAs are strongly enriched in subtelomeric regions where they may facilitate formation of a new telomere following catastrophic telomere loss. In contrast, outside of subtelomeres, the distribution and orientation of SiRTAs appears random. Since truncating the chromosome at most SiRTAs would be lethal, this observation argues against selection for these sequences as sites of telomere addition per se. We find, however, that sequences predicted to function as SiRTAs are significantly more prevalent across the genome than expected by chance. Sequences identified by the algorithm bind the telomeric protein Cdc13, raising the possibility that association of Cdc13 with single-stranded regions generated during the response to DNA damage may facilitate DNA repair more generally.
Collapse
Affiliation(s)
- Katrina Ngo
- Department of Biological Sciences, Vanderbilt University
| | | | | | - E. Anne Hatmaker
- Department of Biological Sciences, Vanderbilt University
- Evolutionary Studies Initiative, Vanderbilt University
| | - Simcha Plotkin
- Department of Biological Sciences, Vanderbilt University
| | - Mason Engle
- Department of Biological Sciences, Vanderbilt University
| | | | - Melissa Goldin
- Department of Biological Sciences, Vanderbilt University
| | | | - Brandt F. Eichman
- Department of Biological Sciences, Vanderbilt University
- Department of Biochemistry, Vanderbilt University
| | - Antonis Rokas
- Department of Biological Sciences, Vanderbilt University
- Evolutionary Studies Initiative, Vanderbilt University
| | | | | |
Collapse
|
26
|
Huda A, Arakawa H, Mazzucco G, Galli M, Petrocelli V, Casola S, Chen L, Doksani Y. The telomerase reverse transcriptase elongates reversed replication forks at telomeric repeats. SCIENCE ADVANCES 2023; 9:eadf2011. [PMID: 36947627 PMCID: PMC10032592 DOI: 10.1126/sciadv.adf2011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Accepted: 02/23/2023] [Indexed: 06/18/2023]
Abstract
The telomerase reverse transcriptase elongates telomeres to prevent replicative senescence. This process requires exposure of the 3'-end, which is thought to occur when two sister telomeres are generated at replication completion. Using two-dimensional agarose gel electrophoresis (2D-gels) and electron microscopy, we found that telomeric repeats are hotspots for replication fork reversal. Fork reversal generates 3' telomeric ends before replication completion. To verify whether these ends are elongated by telomerase, we probed de novo telomeric synthesis in situ and at replication intermediates by reconstituting mutant telomerase that adds a variant telomere sequence. We found variant telomeric repeats overlapping with telomeric reversed forks in 2D-gels, but not with normal forks, nontelomeric reversed forks, or telomeric reversed forks with a C-rich 3'-end. Our results define reversed telomeric forks as a substrate of telomerase during replication.
Collapse
Affiliation(s)
- Armela Huda
- IFOM ETS-The AIRC Institute of Molecular Oncology, Milan, Italy
| | - Hiroshi Arakawa
- IFOM ETS-The AIRC Institute of Molecular Oncology, Milan, Italy
| | - Giulia Mazzucco
- IFOM ETS-The AIRC Institute of Molecular Oncology, Milan, Italy
| | - Martina Galli
- IFOM ETS-The AIRC Institute of Molecular Oncology, Milan, Italy
| | - Valentina Petrocelli
- Institute for Tumor Biology and Experimental Therapy, Frankfurt Cancer Institute, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Stefano Casola
- IFOM ETS-The AIRC Institute of Molecular Oncology, Milan, Italy
| | - Lu Chen
- Nuclear Dynamics and Cancer Program, Cancer Epigenetics Institute, Fox Chase Cancer Center, Philadelphia, PA, USA
- Department of Cancer and Cellular Biology, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA
| | - Ylli Doksani
- IFOM ETS-The AIRC Institute of Molecular Oncology, Milan, Italy
| |
Collapse
|
27
|
Aguilera P, López-Contreras AJ. ATRX, a guardian of chromatin. Trends Genet 2023; 39:505-519. [PMID: 36894374 DOI: 10.1016/j.tig.2023.02.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 02/07/2023] [Accepted: 02/14/2023] [Indexed: 03/09/2023]
Abstract
ATRX (alpha-thalassemia mental retardation X-linked) is one of the most frequently mutated tumor suppressor genes in human cancers, especially in glioma, and recent findings indicate roles for ATRX in key molecular pathways, such as the regulation of chromatin state, gene expression, and DNA damage repair, placing ATRX as a central player in the maintenance of genome stability and function. This has led to new perspectives about the functional role of ATRX and its relationship with cancer. Here, we provide an overview of ATRX interactions and molecular functions and discuss the consequences of its impairment, including alternative lengthening of telomeres and therapeutic vulnerabilities that may be exploited in cancer cells.
Collapse
Affiliation(s)
- Paula Aguilera
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Sevilla - Universidad Pablo de Olavide, Seville, Spain.
| | - Andrés J López-Contreras
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Sevilla - Universidad Pablo de Olavide, Seville, Spain.
| |
Collapse
|
28
|
Heat-Killed Staphylococcus aureus Induces Bone Mass Loss through Telomere Erosion. Int J Mol Sci 2023; 24:ijms24043179. [PMID: 36834587 PMCID: PMC9960843 DOI: 10.3390/ijms24043179] [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: 11/21/2022] [Revised: 01/30/2023] [Accepted: 02/03/2023] [Indexed: 02/09/2023] Open
Abstract
The mechanism of systemic osteoporosis caused by chronic infection is not completely clear, and there is a lack of reasonable interventions for this disease. In this study, heat-killed S. aureus (HKSA) was applied to simulate the inflammation caused by the typical clinical pathogen and to explore the mechanism of systemic bone loss caused by it. In this study, we found that the systemic application of HKSA caused bone loss in mice. Further exploration found that HKSA caused cellular senescence, telomere length shortening, and telomere dysfunction-induced foci (TIF) in limb bones. As a well-known telomerase activator, cycloastragenol (CAG) significantly alleviated HKSA-induced telomere erosion and bone loss. These results suggested that telomere erosion in bone marrow cells is a possible mechanism of HKSA-induced bone loss. CAG may protect against HKSA-induced bone loss by alleviating telomere erosion in bone marrow cells.
Collapse
|
29
|
Effects of Human Papilloma Virus E6/E7 Oncoproteins on Genomic Structure in Head and Neck Squamous Cell Carcinoma. Cancers (Basel) 2022; 14:cancers14246190. [PMID: 36551675 PMCID: PMC9777059 DOI: 10.3390/cancers14246190] [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: 11/26/2022] [Revised: 12/12/2022] [Accepted: 12/14/2022] [Indexed: 12/23/2022] Open
Abstract
Human Papilloma Virus (HPV) is highly prevalent within the U.S., with studies estimating that over 80% of individuals will contract the virus in their lifetime. HPV is considered a primary risk factor for the development and progression of oropharyngeal cancers. The impact of the HPV virus's E6 and E7 oncoproteins on cellular signaling pathways and genomic integration has been extensively characterized. Indirect genomic effects; however, remain relatively unidentified. In this study, we analyzed 83 HPV+ Head and Neck Squamous Cell Carcinoma (HNSCC) patients of varying HPV types. Expression counts of the HPV E6 and E7 oncogenes were estimated across samples and correlated with genomic mutational classes. High expression of E6 and E7 oncoproteins was associated with a greater number of total point mutations, especially on chromosomes 1, 11, and 17, which have been implicated in HPV-mediated cancers in previous studies. Samples with high E6 and E7 expression also exhibited more frequent non-clustered structural variation and a lack of clustered variation altogether. Copy number segments were present with fewer number of repeats in high E6 and E7 expression samples, which is known to correlate with decreased expression of affected genes. E6 and E7 expression was associated with increased activity of several cellular pathways associated in oncogenesis and telomere maintenance. In comprehensively characterizing the effects of the HPV oncoproteins on the human genome, potential mechanisms of HNSCC pathogenesis may be further elucidated.
Collapse
|
30
|
Coll-Bonfill N, Mahajan U, Shashkova EV, Lin CJ, Mecham RP, Gonzalo S. Progerin induces a phenotypic switch in vascular smooth muscle cells and triggers replication stress and an aging-associated secretory signature. GeroScience 2022; 45:965-982. [PMID: 36482259 PMCID: PMC9886737 DOI: 10.1007/s11357-022-00694-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Accepted: 11/17/2022] [Indexed: 12/14/2022] Open
Abstract
Hutchinson-Gilford progeria syndrome is a premature aging disease caused by LMNA gene mutation and the production of a truncated prelamin A protein "progerin" that elicits cellular and organismal toxicity. Progerin accumulates in the vasculature, being especially detrimental for vascular smooth muscle cells (VSMC). Vessel stiffening and aortic atherosclerosis in HGPS patients are accompanied by VSMC depletion in the medial layer, altered extracellular matrix (ECM), and thickening of the adventitial layer. Mechanisms whereby progerin causes massive VSMC loss and vessel alterations remain poorly understood. Mature VSMC retain phenotypic plasticity and can switch to a synthetic/proliferative phenotype. Here, we show that progerin expression in human and mouse VSMC causes a switch towards the synthetic phenotype. This switch elicits some level of replication stress in normal cells, which is exacerbated in the presence of progerin, leading to telomere fragility, genomic instability, and ultimately VSMC death. Calcitriol prevents replication stress, telomere fragility, and genomic instability, reducing VSMC death. In addition, RNA-seq analysis shows induction of a profibrotic and pro-inflammatory aging-associated secretory phenotype upon progerin expression in human primary VSMC. Our data suggest that phenotypic switch-induced replication stress might be an underlying cause of VSMC loss in progeria, which together with loss of contractile features and gain of profibrotic and pro-inflammatory signatures contribute to vascular stiffness in HGPS.
Collapse
Affiliation(s)
- Nuria Coll-Bonfill
- grid.262962.b0000 0004 1936 9342Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, 1100 S Grand Blvd, St Louis, MO 63104 USA
| | - Urvashi Mahajan
- grid.262962.b0000 0004 1936 9342Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, 1100 S Grand Blvd, St Louis, MO 63104 USA
| | - Elena V. Shashkova
- grid.262962.b0000 0004 1936 9342Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, 1100 S Grand Blvd, St Louis, MO 63104 USA
| | - Chien-Jung Lin
- grid.4367.60000 0001 2355 7002Cell Biology and Physiology Department & Department of Medicine, Washington University School of Medicine, St Louis, MO 63108 USA ,grid.262962.b0000 0004 1936 9342Department of Internal Medicine, Cardiovascular Division, Saint Louis University School of Medicine, St Louis, MO 63104 USA
| | - Robert P. Mecham
- grid.4367.60000 0001 2355 7002Cell Biology and Physiology Department & Department of Medicine, Washington University School of Medicine, St Louis, MO 63108 USA
| | - Susana Gonzalo
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, 1100 S Grand Blvd, St Louis, MO, 63104, USA.
| |
Collapse
|
31
|
Sherazi SAM, Abbasi A, Jamil A, Uzair M, Ikram A, Qamar S, Olamide AA, Arshad M, Fried PJ, Ljubisavljevic M, Wang R, Bashir S. Molecular hallmarks of long non-coding RNAs in aging and its significant effect on aging-associated diseases. Neural Regen Res 2022; 18:959-968. [PMID: 36254975 PMCID: PMC9827784 DOI: 10.4103/1673-5374.355751] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Aging is linked to the deterioration of many physical and cognitive abilities and is the leading risk factor for Alzheimer's disease. The growing aging population is a significant healthcare problem globally that researchers must investigate to better understand the underlying aging processes. Advances in microarrays and sequencing techniques have resulted in deeper analyses of diverse essential genomes (e.g., mouse, human, and rat) and their corresponding cell types, their organ-specific transcriptomes, and the tissue involved in aging. Traditional gene controllers such as DNA- and RNA-binding proteins significantly influence such programs, causing the need to sort out long non-coding RNAs, a new class of powerful gene regulatory elements. However, their functional significance in the aging process and senescence has yet to be investigated and identified. Several recent researchers have associated the initiation and development of senescence and aging in mammals with several well-reported and novel long non-coding RNAs. In this review article, we identified and analyzed the evolving functions of long non-coding RNAs in cellular processes, including cellular senescence, aging, and age-related pathogenesis, which are the major hallmarks of long non-coding RNAs in aging.
Collapse
Affiliation(s)
- Syed Aoun Mehmood Sherazi
- Department of Biological Sciences, Faculty of Basic & Applied Sciences, International Islamic University, Islamabad, Pakistan
| | - Asim Abbasi
- Department of Biological Sciences, University of Arkansas, Fayetteville, AR, USA
| | - Abdullah Jamil
- Department of Pharmacology, Government College University, Faisalabad, Pakistan
| | - Mohammad Uzair
- Department of Biological Sciences, Faculty of Basic & Applied Sciences, International Islamic University, Islamabad, Pakistan
| | - Ayesha Ikram
- Department of Bioinformatics and Biotechnology, Government College University, Faisalabad, Pakistan
| | - Shanzay Qamar
- Department of Bioinformatics and Biotechnology, Government College University, Faisalabad, Pakistan
| | | | - Muhammad Arshad
- Department of Biological Sciences, Faculty of Basic & Applied Sciences, International Islamic University, Islamabad, Pakistan
| | - Peter J. Fried
- Department of Neurology, Berenson-Allen Center for Noninvasive Brain Stimulation and Division of Cognitive Neurology, Beth Israel Deaconess Medical Center (KS 158), Harvard Medical School, Boston, MA, USA
| | - Milos Ljubisavljevic
- Department of Physiology, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Ran Wang
- Department of Psychiatry, The First Hospital of Hebei Medical University, Shijiazhuang, Hebei Province, China,Mental Health Institute of Hebei Medical University, Shijiazhuang, Hebei Province, China
| | - Shahid Bashir
- Neuroscience Center, King Fahad Specialist Hospital, Dammam, Saudi Arabia,Correspondence to: Shahid Bashir, .
| |
Collapse
|
32
|
de Lima MF, Freitas MO, Hamedani MK, Rangel-Pozzo A, Zhu XD, Mai S. Consecutive Inhibition of Telomerase and Alternative Lengthening Pathway Promotes Hodgkin's Lymphoma Cell Death. Biomedicines 2022; 10:2299. [PMID: 36140400 PMCID: PMC9496562 DOI: 10.3390/biomedicines10092299] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 08/19/2022] [Accepted: 09/12/2022] [Indexed: 11/16/2022] Open
Abstract
Telomere maintenance is key during cancer development. Malignant cells can either use telomerase or an alternative lengthening of telomere (ALT) pathway to maintain their telomere length. In Hodgkin's Lymphoma (HL), the presence of telomerase activation is established. The activation of ALT has been reported recently. Our data confirm this notion describing co-localization of the phosphorylated form of telomeric repeat-binding factor 1 (pT371-TRF1) with ALT-associated promyelocytic leukemia bodies. Surprisingly, to our knowledge, there are no published studies targeting both telomere maintenance pathways in HL. Consequently, we investigated, for the first time, the effects of both telomerase and ALT inhibition on HL cell viability: We inhibited telomerase and/or ALT, given either individually, simultaneously, or consecutively. We report that the inhibition of telomerase using BIBR1532 followed by ALT inhibition, using trabectedin, caused a decrease of greater than 90% in cell viability in three patient-derived HL cell lines. Our results suggest that HL cells are most vulnerable to the consecutive inhibition of telomerase followed by ALT inhibition.
Collapse
Affiliation(s)
- Matheus Fabiao de Lima
- Department of Physiology and Pathophysiology, CancerCare Manitoba Research Institute, University of Manitoba, Winnipeg, MB R3E 0V9, Canada
| | - Monique Oliveira Freitas
- Genetic Service, Institute of Paediatrics and Puericulture Martagão Gesteira (IPPMG), Federal University of Rio de Janeiro (UFRJ), Rio de Janeiro 21941-912, Brazil
| | - Mohammad K. Hamedani
- Department of Physiology and Pathophysiology, CancerCare Manitoba Research Institute, University of Manitoba, Winnipeg, MB R3E 0V9, Canada
| | - Aline Rangel-Pozzo
- Department of Physiology and Pathophysiology, CancerCare Manitoba Research Institute, University of Manitoba, Winnipeg, MB R3E 0V9, Canada
| | - Xu-Dong Zhu
- Department of Biology, Faculty of Science, McMaster University, Hamilton, ON L8S 4K1, Canada
| | - Sabine Mai
- Department of Physiology and Pathophysiology, CancerCare Manitoba Research Institute, University of Manitoba, Winnipeg, MB R3E 0V9, Canada
| |
Collapse
|
33
|
Yu EY, Cheung NKV, Lue NF. Connecting telomere maintenance and regulation to the developmental origin and differentiation states of neuroblastoma tumor cells. J Hematol Oncol 2022; 15:117. [PMID: 36030273 PMCID: PMC9420296 DOI: 10.1186/s13045-022-01337-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Accepted: 07/28/2022] [Indexed: 11/18/2022] Open
Abstract
A cardinal feature that distinguishes clinically high-risk neuroblastoma from low-risk tumors is telomere maintenance. Specifically, neuroblastoma tumors with either active telomerase or alternative lengthening of telomeres exhibit aggressive growth characteristics that lead to poor outcomes, whereas tumors without telomere maintenance can be managed with observation or minimal treatment. Even though the need for cancer cells to maintain telomere DNA-in order to sustain cell proliferation-is well established, recent studies suggest that the neural crest origin of neuroblastoma may enforce unique relationships between telomeres and tumor malignancy. Specifically in neuroblastoma, telomere structure and telomerase activity are correlated with the adrenergic/mesenchymal differentiation states, and manipulating telomerase activity can trigger tumor cell differentiation. Both findings may reflect features of normal neural crest development. This review summarizes recent advances in the characterization of telomere structure and telomere maintenance mechanisms in neuroblastoma and discusses the findings in the context of relevant literature on telomeres during embryonic and neural development. Understanding the canonical and non-canonical roles of telomere maintenance in neuroblastoma could reveal vulnerabilities for telomere-directed therapies with potential applications to other pediatric malignancies.
Collapse
Affiliation(s)
- Eun Young Yu
- Department of Microbiology & Immunology, W. R. Hearst Microbiology Research Center, Weill Cornell Medicine, 1300 York Avenue, New York, NY, 10065, USA
| | - Nai-Kong V Cheung
- Department of Pediatrics, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY, 10065, USA
| | - Neal F Lue
- Department of Microbiology & Immunology, W. R. Hearst Microbiology Research Center, Weill Cornell Medicine, 1300 York Avenue, New York, NY, 10065, USA.
- Sandra and Edward Meyer Cancer Center, Weill Cornell Medicine, 1300 York Avenue, New York, NY, 10065, USA.
| |
Collapse
|
34
|
He Q, Lin X, Chavez BL, Agrawal S, Lusk BL, Lim CJ. Structures of the human CST-Polα-primase complex bound to telomere templates. Nature 2022; 608:826-832. [PMID: 35830881 DOI: 10.1038/s41586-022-05040-1] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 06/29/2022] [Indexed: 01/26/2023]
Abstract
The mammalian DNA polymerase-α-primase (Polα-primase) complex is essential for DNA metabolism, providing the de novo RNA-DNA primer for several DNA replication pathways1-4 such as lagging-strand synthesis and telomere C-strand fill-in. The physical mechanism underlying how Polα-primase, alone or in partnership with accessory proteins, performs its complicated multistep primer synthesis function is unknown. Here we show that CST, a single-stranded DNA-binding accessory protein complex for Polα-primase, physically organizes the enzyme for efficient primer synthesis. Cryogenic electron microscopy structures of the CST-Polα-primase preinitiation complex (PIC) bound to various types of telomere overhang reveal that template-bound CST partitions the DNA and RNA catalytic centres of Polα-primase into two separate domains and effectively arranges them in RNA-DNA synthesis order. The architecture of the PIC provides a single solution for the multiple structural requirements for the synthesis of RNA-DNA primers by Polα-primase. Several insights into the template-binding specificity of CST, template requirement for assembly of the CST-Polα-primase PIC and activation are also revealed in this study.
Collapse
Affiliation(s)
- Qixiang He
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - Xiuhua Lin
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - Bianca L Chavez
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - Sourav Agrawal
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - Benjamin L Lusk
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - Ci Ji Lim
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA.
| |
Collapse
|
35
|
Zaug AJ, Goodrich KJ, Song JJ, Sullivan AE, Cech TR. Reconstitution of a telomeric replicon organized by CST. Nature 2022; 608:819-825. [PMID: 35831508 PMCID: PMC9402439 DOI: 10.1038/s41586-022-04930-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 06/06/2022] [Indexed: 11/20/2022]
Abstract
Telomeres, the natural ends of linear chromosomes, comprise repeat-sequence DNA and associated proteins1. Replication of telomeres allows continued proliferation of human stem cells and immortality of cancer cells2. This replication requires telomerase3 extension of the single-stranded DNA (ssDNA) of the telomeric G-strand ((TTAGGG)n); the synthesis of the complementary C-strand ((CCCTAA)n) is much less well characterized. The CST (CTC1–STN1–TEN1) protein complex, a DNA polymerase α-primase accessory factor4,5, is known to be required for telomere replication in vivo6–9, and the molecular analysis presented here reveals key features of its mechanism. We find that human CST uses its ssDNA-binding activity to specify the origins for telomeric C-strand synthesis by bound Polα-primase. CST-organized DNA polymerization can copy a telomeric DNA template that folds into G-quadruplex structures, but the challenges presented by this template probably contribute to telomere replication problems observed in vivo. Combining telomerase, a short telomeric ssDNA primer and CST–Polα–primase gives complete telomeric DNA replication, resulting in the same sort of ssDNA 3′ overhang found naturally on human telomeres. We conclude that the CST complex not only terminates telomerase extension10,11 and recruits Polα–primase to telomeric ssDNA4,12,13 but also orchestrates C-strand synthesis. Because replication of the telomere has features distinct from replication of the rest of the genome, targeting telomere-replication components including CST holds promise for cancer therapeutics. The Polα–primase-associated CST complex organizes telomeric C-strand DNA synthesis, and, in combination with telomerase, it carries out complete replication of the single-stranded DNA overhang found at human telomeres.
Collapse
Affiliation(s)
- Arthur J Zaug
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO, USA.,BioFrontiers Institute, University of Colorado Boulder, Boulder, CO, USA.,Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO, USA
| | - Karen J Goodrich
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO, USA.,BioFrontiers Institute, University of Colorado Boulder, Boulder, CO, USA.,Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO, USA
| | - Jessica J Song
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO, USA
| | - Ashley E Sullivan
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO, USA
| | - Thomas R Cech
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO, USA. .,BioFrontiers Institute, University of Colorado Boulder, Boulder, CO, USA. .,Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO, USA.
| |
Collapse
|
36
|
Abstract
The number of (TTAGGG)n repeats at the ends of chromosomes is highly variable between individual chromosomes, between different cells and between species. Progressive loss of telomere repeats limits the proliferation of pre-malignant human cells but also contributes to aging by inducing apoptosis and senescence in normal cells. Despite enormous progress in understanding distinct pathways that result in loss and gain of telomeric DNA in different cell types, many questions remain. Further studies are needed to delineate the role of damage to telomeric DNA, replication errors, chromatin structure, liquid-liquid phase transition, telomeric transcripts (TERRA) and secondary DNA structures such as guanine quadruplex structures, R-loops and T-loops in inducing gains and losses of telomere repeats in different cell types. Limitations of current telomere length measurements techniques and differences in telomere biology between species and different cell types complicate generalizations about the role of telomeres in aging and cancer. Here some of the factors regulating the telomere length in embryonic and adult cells in mammals are discussed from a mechanistic and evolutionary perspective.
Collapse
Affiliation(s)
- Peter Lansdorp
- Terry Fox Laboratory, British Columbia (BC) Cancer Agency, Vancouver, BC, Canada
- Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
- *Correspondence: Peter Lansdorp,
| |
Collapse
|
37
|
Aguilera P, Dubarry M, Hardy J, Lisby M, Simon MN, Géli V. Telomeric C-circles localize at nuclear pore complexes in Saccharomyces cerevisiae. EMBO J 2022; 41:e108736. [PMID: 35147992 PMCID: PMC8922269 DOI: 10.15252/embj.2021108736] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 01/17/2022] [Accepted: 01/21/2022] [Indexed: 11/09/2022] Open
Abstract
As in human cells, yeast telomeres can be maintained in cells lacking telomerase activity by recombination-based mechanisms known as ALT (Alternative Lengthening of Telomeres). A hallmark of ALT human cancer cells are extrachromosomal telomeric DNA elements called C-circles, whose origin and function have remained unclear. Here, we show that extrachromosomal telomeric C-circles in yeast can be detected shortly after senescence crisis and concomitantly with the production of survivors arising from "type II" recombination events. We uncover that C-circles bind to the nuclear pore complex (NPC) and to the SAGA-TREX2 complex, similar to other non-centromeric episomal DNA. Disrupting the integrity of the SAGA/TREX2 complex affects both C-circle binding to NPCs and type II telomere recombination, suggesting that NPC tethering of C-circles facilitates formation and/or propagation of the long telomere repeats characteristic of type II survivors. Furthermore, we find that disruption of the nuclear diffusion barrier impairs type II recombination. These results support a model in which concentration of C-circles at NPCs benefits type II telomere recombination, highlighting the importance of spatial coordination in ALT-type mechanisms of telomere maintenance.
Collapse
Affiliation(s)
- Paula Aguilera
- Marseille Cancer Research Center (CRCM), U1068 Inserm, UMR7258 CNRS, Institut Paoli-Calmettes, Equipe labellisée Ligue, Aix Marseille University, Marseille, France
| | - Marion Dubarry
- Marseille Cancer Research Center (CRCM), U1068 Inserm, UMR7258 CNRS, Institut Paoli-Calmettes, Equipe labellisée Ligue, Aix Marseille University, Marseille, France
| | - Julien Hardy
- Marseille Cancer Research Center (CRCM), U1068 Inserm, UMR7258 CNRS, Institut Paoli-Calmettes, Equipe labellisée Ligue, Aix Marseille University, Marseille, France
| | - Michael Lisby
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Marie-Noëlle Simon
- Marseille Cancer Research Center (CRCM), U1068 Inserm, UMR7258 CNRS, Institut Paoli-Calmettes, Equipe labellisée Ligue, Aix Marseille University, Marseille, France
| | - Vincent Géli
- Marseille Cancer Research Center (CRCM), U1068 Inserm, UMR7258 CNRS, Institut Paoli-Calmettes, Equipe labellisée Ligue, Aix Marseille University, Marseille, France
| |
Collapse
|
38
|
Rabbani MAG, Tonini ML, Afrin M, Li B. POLIE suppresses telomerase-mediated telomere G-strand extension and helps ensure proper telomere C-strand synthesis in trypanosomes. Nucleic Acids Res 2022; 50:2036-2050. [PMID: 35061898 PMCID: PMC8887473 DOI: 10.1093/nar/gkac023] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 01/05/2022] [Accepted: 01/07/2022] [Indexed: 11/15/2022] Open
Abstract
Trypanosoma brucei causes human African trypanosomiasis and sequentially expresses distinct VSGs, its major surface antigen, to achieve host immune evasion. VSGs are monoallelically expressed from subtelomeric loci, and telomere proteins regulate VSG monoallelic expression and VSG switching. T. brucei telomerase is essential for telomere maintenance, but no regulators of telomerase have been identified. T. brucei appears to lack OB fold-containing telomere-specific ssDNA binding factors that are critical for coordinating telomere G- and C-strand syntheses in higher eukaryotes. We identify POLIE as a telomere protein essential for telomere integrity. POLIE-depleted cells have more frequent VSG gene conversion-mediated VSG switching and an increased amount of telomeric circles (T-circles), indicating that POLIE suppresses DNA recombination at the telomere/subtelomere. POLIE-depletion elongates telomere 3' overhangs dramatically, indicating that POLIE is essential for coordinating DNA syntheses of the two telomere strands. POLIE depletion increases the level of telomerase-dependent telomere G-strand extension, identifying POLIE as the first T. brucei telomere protein that suppresses telomerase. Furthermore, depletion of POLIE results in an elevated telomeric C-circle level, suggesting that the telomere C-strand experiences replication stress and that POLIE may promote telomere C-strand synthesis. Therefore, T. brucei uses a novel mechanism to coordinate the telomere G- and C-strand DNA syntheses.
Collapse
Affiliation(s)
- M A G Rabbani
- Center for Gene Regulation in Health and Disease, Department of Biological, Geological, and Environmental Sciences, College of Sciences and Health Professions, Cleveland State University, 2121 Euclid Avenue, Cleveland, OH 44115, USA
| | - Maiko Luis Tonini
- Center for Gene Regulation in Health and Disease, Department of Biological, Geological, and Environmental Sciences, College of Sciences and Health Professions, Cleveland State University, 2121 Euclid Avenue, Cleveland, OH 44115, USA
| | - Marjia Afrin
- Center for Gene Regulation in Health and Disease, Department of Biological, Geological, and Environmental Sciences, College of Sciences and Health Professions, Cleveland State University, 2121 Euclid Avenue, Cleveland, OH 44115, USA
| | - Bibo Li
- Center for Gene Regulation in Health and Disease, Department of Biological, Geological, and Environmental Sciences, College of Sciences and Health Professions, Cleveland State University, 2121 Euclid Avenue, Cleveland, OH 44115, USA
- Case Comprehensive Cancer Center, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland OH 44195, USA
- Center for RNA Science and Therapeutics, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| |
Collapse
|
39
|
Telomeres, aging, and cancer: the big picture. Blood 2022; 139:813-821. [PMID: 35142846 DOI: 10.1182/blood.2021014299] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 12/16/2021] [Indexed: 12/13/2022] Open
Abstract
The role of telomeres in human health and disease is yet to be fully understood. The limitations of mouse models for the study of human telomere biology and difficulties in accurately measuring the length of telomere repeats in chromosomes and cells have diverted attention from many important and relevant observations. The goal of this perspective is to summarize some of these observations and to discuss the antagonistic role of telomere loss in aging and cancer in the context of developmental biology, cell turnover, and evolution. It is proposed that both damage to DNA and replicative loss of telomeric DNA contribute to aging in humans, with the differences in leukocyte telomere length between humans being linked to the risk of developing specific diseases. These ideas are captured in the Telomere Erosion in Disposable Soma theory of aging proposed herein.
Collapse
|
40
|
Campitelli BE, Razzaque S, Barbero B, Abdulkina LR, Hall MH, Shippen DE, Juenger TE, Shakirov EV. Plasticity, pleiotropy and fitness trade-offs in Arabidopsis genotypes with different telomere lengths. THE NEW PHYTOLOGIST 2022; 233:1939-1952. [PMID: 34826163 PMCID: PMC9218941 DOI: 10.1111/nph.17880] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Accepted: 11/14/2021] [Indexed: 05/12/2023]
Abstract
Telomere length has been implicated in the organismal response to stress, but the underlying mechanisms are unknown. Here we examine the impact of telomere length changes on the responses to three contrasting abiotic environments in Arabidopsis, and measure 32 fitness, developmental, physiological and leaf-level anatomical traits. We report that telomere length in wild-type and short-telomere mutants is resistant to abiotic stress, while the elongated telomeres in ku70 mutants are more plastic. We detected significant pleiotropic effects of telomere length on flowering time and key leaf physiological and anatomical traits. Furthermore, our data reveal a significant genotype by environment (G × E) interaction for reproductive fitness, with the benefits and costs to performance depending on the growth conditions. These results imply that life-history trade-offs between flowering time and reproductive fitness are impacted by telomere length variation. We postulate that telomere length in plants is subject to natural selection imposed by different environments.
Collapse
Affiliation(s)
- Brandon E. Campitelli
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA
- Texas Institute for Discovery Education in Sciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Samsad Razzaque
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Borja Barbero
- Department of Biochemistry and Biophysics, Texas A&M University, 2128 TAMU, College Station, TX 77843-2128, USA
| | - Liliia R. Abdulkina
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan, Republic of Tatarstan 420008, Russia
| | - Mitchell H. Hall
- Department of Biological Sciences, College of Science, Marshall University, Huntington, WV 25701, USA
| | - Dorothy E. Shippen
- Department of Biochemistry and Biophysics, Texas A&M University, 2128 TAMU, College Station, TX 77843-2128, USA
| | - Thomas E. Juenger
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Eugene V. Shakirov
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan, Republic of Tatarstan 420008, Russia
- Department of Biological Sciences, College of Science, Marshall University, Huntington, WV 25701, USA
- Department of Biomedical Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, WV 25755, USA
| |
Collapse
|
41
|
Xu M, Chigumira T, Chen Z, Tones J, Zhao R, Dahl KN, Chenoweth DM, Zhang H. CRISPR Cas13-Based Tools to Track and Manipulate Endogenous Telomeric Repeat-Containing RNAs in Live Cells. Front Mol Biosci 2022; 8:785160. [PMID: 35174207 PMCID: PMC8841788 DOI: 10.3389/fmolb.2021.785160] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 12/22/2021] [Indexed: 12/23/2022] Open
Abstract
TERRA, TElomeric Repeat-containing RNA, is a long non-coding RNA transcribed from telomeres. Emerging evidence indicates that TERRA regulates telomere maintenance and chromosome end protection in normal and cancerous cells. However, the mechanism of how TERRA contributes to telomere functions is still unclear, partially owing to the shortage of approaches to track and manipulate endogenous TERRA molecules in live cells. Here, we developed a method to visualize TERRA in live cells via a combination of CRISPR Cas13 RNA labeling and SunTag technology. Single-particle tracking reveals that TERRA foci undergo anomalous diffusion in a manner that depends on the timescale and telomeric localization. Furthermore, we used a chemically-induced protein dimerization system to manipulate TERRA subcellular localization in live cells. Overall, our approaches to monitor and control TERRA locations in live cells provide powerful tools to better understand its roles in telomere maintenance and genomic integrity.
Collapse
Affiliation(s)
- Meng Xu
- Department of Biological Sciences, Mellon College of Science, Carnegie Mellon University, Pittsburgh, PA, United States
| | - Tafadzwa Chigumira
- Department of Chemical Engineering, College of Engineering, Carnegie Mellon University, Pittsburgh, PA, United States
| | - Ziheng Chen
- Department of Biological Sciences, Mellon College of Science, Carnegie Mellon University, Pittsburgh, PA, United States
| | - Jason Tones
- Department of Biological Sciences, Mellon College of Science, Carnegie Mellon University, Pittsburgh, PA, United States
| | - Rongwei Zhao
- Department of Biological Sciences, Mellon College of Science, Carnegie Mellon University, Pittsburgh, PA, United States
| | - Kris Noel Dahl
- Department of Chemical Engineering, College of Engineering, Carnegie Mellon University, Pittsburgh, PA, United States
| | - David M. Chenoweth
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, United States
| | - Huaiying Zhang
- Department of Biological Sciences, Mellon College of Science, Carnegie Mellon University, Pittsburgh, PA, United States
| |
Collapse
|
42
|
Epum EA, Haber JE. DNA replication: the recombination connection. Trends Cell Biol 2022; 32:45-57. [PMID: 34384659 PMCID: PMC8688190 DOI: 10.1016/j.tcb.2021.07.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 07/18/2021] [Accepted: 07/20/2021] [Indexed: 01/03/2023]
Abstract
Failure to complete DNA replication is one of the major sources of genome instability leading to aneuploidy, chromosome breakage, and chromosome rearrangements that are associated with human cancer. One of the surprising revelations of the past decade is that the completion of replication at so-called common fragile sites (CFS) occurs very late in the cell cycle - at mitosis - through a process termed MiDAS (mitotic DNA synthesis). MiDAS is strongly related to another cancer-promoting phenomenon: the activation of alternative lengthening of telomeres (ALT). Our understanding of the mechanisms of ALT and MiDAS in mammalian cells has drawn heavily from recent advances in the study of break-induced replication (BIR), especially in budding yeast. We provide new insights into the BIR, MiDAS, and ALT pathways and their shared similarities.
Collapse
|
43
|
Payliss BJ, Patel A, Sheppard AC, Wyatt HDM. Exploring the Structures and Functions of Macromolecular SLX4-Nuclease Complexes in Genome Stability. Front Genet 2021; 12:784167. [PMID: 34804132 PMCID: PMC8599992 DOI: 10.3389/fgene.2021.784167] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 10/21/2021] [Indexed: 12/15/2022] Open
Abstract
All organisms depend on the ability of cells to accurately duplicate and segregate DNA into progeny. However, DNA is frequently damaged by factors in the environment and from within cells. One of the most dangerous lesions is a DNA double-strand break. Unrepaired breaks are a major driving force for genome instability. Cells contain sophisticated DNA repair networks to counteract the harmful effects of genotoxic agents, thus safeguarding genome integrity. Homologous recombination is a high-fidelity, template-dependent DNA repair pathway essential for the accurate repair of DNA nicks, gaps and double-strand breaks. Accurate homologous recombination depends on the ability of cells to remove branched DNA structures that form during repair, which is achieved through the opposing actions of helicases and structure-selective endonucleases. This review focuses on a structure-selective endonuclease called SLX1-SLX4 and the macromolecular endonuclease complexes that assemble on the SLX4 scaffold. First, we discuss recent developments that illuminate the structure and biochemical properties of this somewhat atypical structure-selective endonuclease. We then summarize the multifaceted roles that are fulfilled by human SLX1-SLX4 and its associated endonucleases in homologous recombination and genome stability. Finally, we discuss recent work on SLX4-binding proteins that may represent integral components of these macromolecular nuclease complexes, emphasizing the structure and function of a protein called SLX4IP.
Collapse
Affiliation(s)
- Brandon J Payliss
- Department of Biochemistry, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Ayushi Patel
- Department of Biochemistry, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Anneka C Sheppard
- Department of Biochemistry, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Haley D M Wyatt
- Department of Biochemistry, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada.,Canada Research Chairs Program, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| |
Collapse
|
44
|
Gueiderikh A, Maczkowiak-Chartois F, Rosselli F. A new frontier in Fanconi anemia: From DNA repair to ribosome biogenesis. Blood Rev 2021; 52:100904. [PMID: 34750031 DOI: 10.1016/j.blre.2021.100904] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 10/14/2021] [Accepted: 10/26/2021] [Indexed: 12/27/2022]
Abstract
Described by Guido Fanconi almost 100 years ago, Fanconi anemia (FA) is a rare genetic disease characterized by developmental abnormalities, bone marrow failure (BMF) and cancer predisposition. The proteins encoded by FA-mutated genes (FANC proteins) and assembled in the so-called FANC/BRCA pathway have key functions in DNA repair and replication safeguarding, which loss leads to chromosome structural aberrancies. Therefore, since the 1980s, FA has been considered a genomic instability and chromosome fragility syndrome. However, recent findings have demonstrated new and unexpected roles of FANC proteins in nucleolar homeostasis and ribosome biogenesis, the alteration of which impacts cellular proteostasis. Here, we review the different cellular, biochemical and molecular anomalies associated with the loss of function of FANC proteins and discuss how these anomalies contribute to BMF by comparing FA to other major inherited BMF syndromes. Our aim is to determine the extent to which alterations in the DNA damage response in FA contribute to BMF compared to the consequences of the loss of function of the FANC/BRCA pathway on the other roles of the pathway.
Collapse
Affiliation(s)
- Anna Gueiderikh
- CNRS - UMR9019, Équipe labellisée "La Ligue contre le Cancer", 94805 Villejuif, France; Gustave Roussy Cancer Center, 94805 Villejuif, France; Université Paris-Saclay - Paris Sud, Orsay, France.
| | - Frédérique Maczkowiak-Chartois
- CNRS - UMR9019, Équipe labellisée "La Ligue contre le Cancer", 94805 Villejuif, France; Gustave Roussy Cancer Center, 94805 Villejuif, France; Université Paris-Saclay - Paris Sud, Orsay, France.
| | - Filippo Rosselli
- CNRS - UMR9019, Équipe labellisée "La Ligue contre le Cancer", 94805 Villejuif, France; Gustave Roussy Cancer Center, 94805 Villejuif, France; Université Paris-Saclay - Paris Sud, Orsay, France.
| |
Collapse
|
45
|
Nickens DG, Bochman ML. Characterization of the telomerase modulating activities of yeast DNA helicases. Methods Enzymol 2021; 661:327-342. [PMID: 34776218 DOI: 10.1016/bs.mie.2021.08.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Eukaryotes with linear chromosomes circumvent the end replication problem via the action of a specialized ribonucleoprotein reverse transcriptase known as telomerase. Cells lacking telomerase activity will senesce when their chromosome ends shorten to a critical length. In contrast, cancer cells can become immortalized by upregulating telomerase to lengthen telomeres during each cycle of DNA replication. Thus, the regulation of telomerase is critical for normal telomere homeostasis. Of the various known ways that telomerase activity is modulated in vivo, recent studies have demonstrated that DNA helicases are involved. In Saccharomyces cerevisiae, the Hrq1 and Pif1 helicases act in a pathway that regulates telomerase extension at telomeres and at DNA double-strand DNA breaks. In vitro analysis demonstrates that when these helicases are combined in reactions, they synergistically inhibit or stimulate telomerase activity depending on which helicase is catalytically active. Here, we describe the methods for the overproduction and purification of Hrq1 and Pif1. We also report the preparation of partially purified cell extracts with telomerase activity and how the effects of these helicase on telomerase activity can be assessed in vitro.
Collapse
Affiliation(s)
- David G Nickens
- Molecular & Cellular Biochemistry Department, Indiana University, Bloomington, IN, United States
| | - Matthew L Bochman
- Molecular & Cellular Biochemistry Department, Indiana University, Bloomington, IN, United States.
| |
Collapse
|
46
|
Bolzán AD. Mutagen-induced telomere instability in human cells. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2021; 868-869:503387. [PMID: 34454696 DOI: 10.1016/j.mrgentox.2021.503387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 07/13/2021] [Accepted: 07/18/2021] [Indexed: 11/27/2022]
Abstract
Telomere instability is one of the main sources of genome instability and may result from chromosome end loss (due to chromosome breakage at one or both ends) or, more frequently, telomere dysfunction. Dysfunctional telomeres arise when they lose their end-capping function or become critically short, which causes chromosomal termini to behave like a DNA double-strand break. Telomere instability may occur at the chromosomal or at the molecular level, giving rise, respectively, to telomere-related chromosomal aberrations or the loss or modification of any of the components of the telomere (telomere DNA, telomere-associated proteins, or telomere RNA). Since telomeres play a fundamental role in maintaining genome stability, the study of telomere instability in cells exposed to mutagens is of great importance to understand the telomere-driven genomic instability present in those cells. In the present review, we will focus on the current knowledge about telomere instability induced by physical, chemical, and biological mutagens in human cells.
Collapse
Affiliation(s)
- Alejandro D Bolzán
- Laboratorio de Citogenética y Mutagénesis, Instituto Multidisciplinario de Biología Celular (IMBICE, CONICET-CICPBA-UNLP), calle 526 y Camino General Belgrano, B1906APO La Plata, Buenos Aires, Argentina; Universidad Nacional de La Plata, Facultad de Ciencias Naturales y Museo, calle 60 y 122, La Plata, Buenos Aires, Argentina.
| |
Collapse
|