101
|
Méndez-Pertuz M, Martínez P, Blanco-Aparicio C, Gómez-Casero E, Belen García A, Martínez-Torrecuadrada J, Palafox M, Cortés J, Serra V, Pastor J, Blasco MA. Modulation of telomere protection by the PI3K/AKT pathway. Nat Commun 2017; 8:1278. [PMID: 29097657 PMCID: PMC5668434 DOI: 10.1038/s41467-017-01329-2] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 09/11/2017] [Indexed: 11/23/2022] Open
Abstract
Telomeres and the insulin/PI3K pathway are considered hallmarks of aging and cancer. Here, we describe a role for PI3K/AKT in the regulation of TRF1, an essential component of the shelterin complex. PI3K and AKT chemical inhibitors reduce TRF1 telomeric foci and lead to increased telomeric DNA damage and fragility. We identify the PI3Kα isoform as responsible for this TRF1 inhibition. TRF1 is phosphorylated at different residues by AKT and these modifications regulate TRF1 protein stability and TRF1 binding to telomeric DNA in vitro and are important for in vivo TRF1 telomere location and cell viability. Patient-derived breast cancer PDX mouse models that effectively respond to a PI3Kα specific inhibitor, BYL719, show decreased TRF1 levels and increased DNA damage. These findings functionally connect two of the major pathways for cancer and aging, telomeres and the PI3K pathway, and pinpoint PI3K and AKT as novel targets for chemical modulation of telomere protection. Regulation of telomeres and the insulin/PI3K pathway both have roles in aging and cancer development but have not been functionally linked. Here the authors demonstrate that PI3K, via downstream targets, regulates TRF1 via phosphorylation.
Collapse
Affiliation(s)
- Marinela Méndez-Pertuz
- Telomeres and Telomerase Group, Molecular Oncology Program, Spanish National Cancer Centre (CNIO), Melchor Fernández Almagro 3, Madrid, E-28029, Spain
| | - Paula Martínez
- Telomeres and Telomerase Group, Molecular Oncology Program, Spanish National Cancer Centre (CNIO), Melchor Fernández Almagro 3, Madrid, E-28029, Spain
| | - Carmen Blanco-Aparicio
- Experimental Therapeutics Program, Spanish National Cancer Centre (CNIO), Melchor Fernández Almagro 3, Madrid, E-28029, Spain
| | - Elena Gómez-Casero
- Experimental Therapeutics Program, Spanish National Cancer Centre (CNIO), Melchor Fernández Almagro 3, Madrid, E-28029, Spain
| | - Ana Belen García
- Experimental Therapeutics Program, Spanish National Cancer Centre (CNIO), Melchor Fernández Almagro 3, Madrid, E-28029, Spain
| | - Jorge Martínez-Torrecuadrada
- Biotechnology Program, Spanish National Cancer Centre (CNIO), Melchor Fernández Almagro 3, Madrid, E-28029, Spain
| | - Marta Palafox
- Experimental Therapeutics Group, Vall d´Hebron Institute of Oncology (VHIO), Natzaret 115-117, Barcelona, E-08035, Spain
| | - Javier Cortés
- Experimental Therapeutics Group, Vall d´Hebron Institute of Oncology (VHIO), Natzaret 115-117, Barcelona, E-08035, Spain
| | - Violeta Serra
- Experimental Therapeutics Group, Vall d´Hebron Institute of Oncology (VHIO), Natzaret 115-117, Barcelona, E-08035, Spain
| | - Joaquin Pastor
- Experimental Therapeutics Program, Spanish National Cancer Centre (CNIO), Melchor Fernández Almagro 3, Madrid, E-28029, Spain
| | - Maria A Blasco
- Telomeres and Telomerase Group, Molecular Oncology Program, Spanish National Cancer Centre (CNIO), Melchor Fernández Almagro 3, Madrid, E-28029, Spain.
| |
Collapse
|
102
|
Andrade RC, Dos Santos ACE, de Aguirre Neto JC, Nevado J, Lapunzina P, Vargas FR. TP53 and CDKN1A mutation analysis in families with Li-Fraumeni and Li-Fraumeni like syndromes. Fam Cancer 2017; 16:243-248. [PMID: 27714481 DOI: 10.1007/s10689-016-9935-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Li-Fraumeni and Li-Fraumeni like syndromes (LFS/LFL) represent rare cancer-prone conditions associated mostly with sarcomas, breast cancer, brain tumors, and adrenocortical carcinomas. TP53 germline mutations are present in up to 80 % of families with classic Li-Fraumeni syndrome, and in 20-60 % of families with Li-Fraumeni like phenotypes. The frequency of LFS/LFL families with no TP53 mutations detected suggests the involvement of other genes in the syndrome. In this study, we searched for mutations in TP53 in 39 probands from families with criteria for LFS/LFL. We also searched for mutations in the gene encoding the main mediator of p53 in cell cycle arrest, CDKN1A/p21, in all patients with no mutations in TP53. Eight probands carried germline disease-causing mutations in TP53: six missense mutations and two partial gene deletions. No mutations in CDKN1A coding region were detected. TP53 partial deletions in our cohort represented 25 % (2/8) of the mutations found, a much higher frequency than usually reported, emphasizing the need to search for TP53 rearrangements in patients with LFS/LFL phenotypes. Two benign tumors were detected in two TP53 mutation carriers: an adrenocortical adenoma and a neurofibroma, which raises a question about the possible implication of TP53 mutations on the development of such lesions.
Collapse
Affiliation(s)
| | | | | | - Julián Nevado
- INGEMM, Instituto de Genética Médica y Molecular, IdiPAZ-CIBERER, Universidad Autónoma de Madrid, Madrid, Spain
| | - Pablo Lapunzina
- INGEMM, Instituto de Genética Médica y Molecular, IdiPAZ-CIBERER, Universidad Autónoma de Madrid, Madrid, Spain
| | - Fernando Regla Vargas
- Genetics Division, Instituto Nacional de Câncer, Rio de Janeiro, Brazil. .,Genetics and Molecular Biology Department, Universidade Federal do Estado do Rio de Janeiro, Rio de Janeiro, Brazil. .,Birth Defects Epidemiology Laboratory, Fundação Oswaldo Cruz, Av. Brasil 4365 - Pavilhão Leônidas Deane Sala 617, Manguinhos, Rio de Janeiro, RJ, 21040-900, Brazil.
| |
Collapse
|
103
|
Jouenne F, Chauvot de Beauchene I, Bollaert E, Avril MF, Caron O, Ingster O, Lecesne A, Benusiglio P, Terrier P, Caumette V, Pissaloux D, de la Fouchardière A, Cabaret O, N'Diaye B, Velghe A, Bougeard G, Mann GJ, Koscielny S, Barrett JH, Harland M, Newton-Bishop J, Gruis N, Van Doorn R, Gauthier-Villars M, Pierron G, Stoppa-Lyonnet D, Coupier I, Guimbaud R, Delnatte C, Scoazec JY, Eggermont AM, Feunteun J, Tchertanov L, Demoulin JB, Frebourg T, Bressac-de Paillerets B. Germline CDKN2A/P16INK4A mutations contribute to genetic determinism of sarcoma. J Med Genet 2017; 54:607-612. [PMID: 28592523 DOI: 10.1136/jmedgenet-2016-104402] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 03/13/2017] [Accepted: 03/14/2017] [Indexed: 01/01/2023]
Abstract
BACKGROUND Sarcomas are rare mesenchymal malignancies whose pathogenesis is poorly understood; both environmental and genetic risk factors could contribute to their aetiology. METHODS AND RESULTS We performed whole-exome sequencing (WES) in a familial aggregation of three individuals affected with soft-tissue sarcoma (STS) without TP53 mutation (Li-Fraumeni-like, LFL) and found a shared pathogenic mutation in CDKN2A tumour suppressor gene. We searched for individuals with sarcoma among 474 melanoma-prone families with a CDKN2A-/+ genotype and for CDKN2A mutations in 190 TP53-negative LFL families where the index case was a sarcoma. Including the initial family, eight independent sarcoma cases carried a germline mutation in the CDKN2A/p16INK4A gene. In five out of seven formalin-fixed paraffin-embedded sarcomas, heterozygosity was lost at germline CDKN2A mutations sites demonstrating complete loss of function. As sarcomas are rare in CDKN2A/p16INK4A carriers, we searched in constitutional WES of nine carriers for potential modifying rare variants and identified three in platelet-derived growth factor receptor (PDGFRA) gene. Molecular modelling showed that two never-described variants could impact the PDGFRA extracellular domain structure. CONCLUSION Germline mutations in CDKN2A/P16INK4A, a gene known to predispose to hereditary melanoma, pancreatic cancer and tobacco-related cancers, account also for a subset of hereditary sarcoma. In addition, we identified PDGFRA as a candidate modifier gene.
Collapse
Affiliation(s)
- Fanélie Jouenne
- Département de Biologie et Pathologie Médicales, Gustave Roussy, Université Paris-Saclay, Villejuif, France
- INSERM, U1186, Université Paris-Saclay, Villejuif, France
| | | | - Emeline Bollaert
- De Duve Institute, Université Catholique de Louvain, Brussels, Belgium
| | - Marie-Françoise Avril
- Department of Dermatology, Assistance Publique-Hopitaux de Paris, Hopital Cochin Tarnier, Paris, France
- Faculté de Médecine, Paris 5 Descartes, Paris, France
| | - Olivier Caron
- Département de Médecine Oncologique, Gustave Roussy, Université Paris-Saclay, Villejuif, France
| | | | - Axel Lecesne
- Département de Médecine Oncologique, Gustave Roussy, Université Paris-Saclay, Villejuif, France
| | - Patrick Benusiglio
- Département de Médecine Oncologique, Gustave Roussy, Université Paris-Saclay, Villejuif, France
| | - Philippe Terrier
- Département de Biologie et Pathologie Médicales, Gustave Roussy, Université Paris-Saclay, Villejuif, France
| | - Vincent Caumette
- Département de Biologie et Pathologie Médicales, Gustave Roussy, Université Paris-Saclay, Villejuif, France
| | - Daniel Pissaloux
- Department of Pathology, Centre Leon Bérard, Lyon, Rhône-Alpes, France
| | | | - Odile Cabaret
- Département de Biologie et Pathologie Médicales, Gustave Roussy, Université Paris-Saclay, Villejuif, France
| | - Birama N'Diaye
- Département de Biologie et Pathologie Médicales, Gustave Roussy, Université Paris-Saclay, Villejuif, France
| | - Amélie Velghe
- De Duve Institute, Université Catholique de Louvain, Brussels, Belgium
| | - Gaelle Bougeard
- Faculty of Medicine, INSERM U1079, Normandy University, Rouen, France
- Department of Genetics, Rouen University Hospital, Normandy Centre for Genomic and personalized Medicine, Rouen, Haute-Normandie, France
| | - Graham J Mann
- Centre for Cancer Research, Weastmead Institute for Medical Research and Melanoma Institute, Sydney, New South Wales, Australia
| | - Serge Koscielny
- Service de Biostatistiques et d'Epidemiologie, Gustave Roussy, Villejuif, France
- INSERM U1018, CESP, Université Paris-Sud, Université Paris-Saclay, Villejuif, France
| | - Jennifer H Barrett
- Section of Epidemiology and Biostatistics, Leeds Institute of Cancer and Pathology, University of Leeds, Leeds, UK
| | - Mark Harland
- Section of Epidemiology and Biostatistics, Leeds Institute of Cancer and Pathology, University of Leeds, Leeds, UK
| | - Julia Newton-Bishop
- Section of Epidemiology and Biostatistics, Leeds Institute of Cancer and Pathology, University of Leeds, Leeds, UK
| | - Nelleke Gruis
- Department of Dermatology, Leiden University Medical Center, Leiden, The Netherlands
| | - Remco Van Doorn
- Department of Dermatology, Leiden University Medical Center, Leiden, The Netherlands
| | | | - Gaelle Pierron
- Institut Curie Hospital Group, Service de Génétique, Paris, France
| | | | - Isabelle Coupier
- Hopital Arnaud de Villeneuve, Service de Génétique Médicale et Oncogénétique, CHU de Montpellier, Montpellier, France
- CRCM Val d'Aurellle, INSERM U896, Montpellier, France
| | | | - Capucine Delnatte
- Unité d'Oncogénétique, Centre René Gauducheau, Nantes Saint Herblain, France
| | - Jean-Yves Scoazec
- Département de Biologie et Pathologie Médicales, Gustave Roussy, Université Paris-Saclay, Villejuif, France
| | - Alexander M Eggermont
- INSERM U1015 and Faculté de médecine, Gustave Roussy, Université Paris-Saclay, Villejuif, France
| | - Jean Feunteun
- CNRS UMR8200, Gustave Roussy, Université Paris-Saclay, Villejuif, France
| | - Luba Tchertanov
- Centre de Mathématiques et de leurs applications, Ecole Normale Supérieure de Cachan, Université Paris-Saclay, Cachan, France
| | | | - Thierry Frebourg
- Faculty of Medicine, INSERM U1079, Normandy University, Rouen, France
- Department of Genetics, Rouen University Hospital, Normandy Centre for Genomic and personalized Medicine, Rouen, Haute-Normandie, France
| | - Brigitte Bressac-de Paillerets
- Département de Biologie et Pathologie Médicales, Gustave Roussy, Université Paris-Saclay, Villejuif, France
- INSERM, U1186, Université Paris-Saclay, Villejuif, France
| |
Collapse
|
104
|
Calvete O, Garcia-Pavia P, Domínguez F, Bougeard G, Kunze K, Braeuninger A, Teule A, Lasa A, Ramón Y Cajal T, Llort G, Fernández V, Lázaro C, Urioste M, Benitez J. The wide spectrum of POT1 gene variants correlates with multiple cancer types. Eur J Hum Genet 2017; 25:1278-1281. [PMID: 28853721 DOI: 10.1038/ejhg.2017.134] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 07/19/2017] [Accepted: 07/21/2017] [Indexed: 01/13/2023] Open
Abstract
The POT1 protein binds and protects telomeres. Germline variants in the POT1 gene have recently been shown to be associated with risk of developing tumors in different tissues such as familial chronic lymphocytic leukemia, colorectal, glioma and melanoma tumors. Recently, we uncovered a variant in the POT1 gene (p.R117C) as causative of familial cardiac angiosarcomas (CAS) in Li-Fraumeni-like (LFL) syndrome families. Our in silico studies predicted that this protein had lost the ability to interact with TPP1 and single-stranded DNA. In vitro studies corroborated this prediction and showed that this lack of function leads to abnormally long telomeres. To better understand the POT1 gene and its role with tumorigenesis, we extended the study to LFL (with and without members affected with angiosarcomas (AS)) and sporadic AS and cardiac sarcomas. We found POT1 variants in the 20% of the families with members affected with AS and 10% of sporadic AS and sarcomas. In silico studies predicted that these new variants were damaging in the same manner as previously described for the POT1 p.R117C variants. The wide spectrum of variants in the POT1 gene leading to tumorigenesis in different tissues demonstrates its general importance. Study of the POT1 gene should be considered as routine diagnostic in these cancers.
Collapse
Affiliation(s)
- Oriol Calvete
- Human Genetics Group, Spanish National Cancer Research Center (CNIO), Madrid, Spain.,Center for Biomedical Network Research on Rare Diseases (CIBERER), Madrid, Spain
| | - Pablo Garcia-Pavia
- Department of Cardiology, Hospital Universitario Puerta de Hierro, Madrid, Spain.,Center for Biomedical Network Research on Cardiovascular Diseases (CIBERCV), Madrid, Spain.,Francisco de Vitoria University, Madrid, Spain
| | - Fernando Domínguez
- Department of Cardiology, Hospital Universitario Puerta de Hierro, Madrid, Spain.,Center for Biomedical Network Research on Cardiovascular Diseases (CIBERCV), Madrid, Spain.,Spanish National Cardiovascular Research Center (CNIC), Madrid, Spain
| | - Gaelle Bougeard
- Normandie University, UNIROUEN, Inserm U1245 and Rouen University Hospital, Department of Genetics, Normandy Centre for Genomic and Personalized Medicine, Rouen, France
| | - Kristin Kunze
- Department of Pathology, Justus-Liebig-University Giessen, Giessen, Germany
| | | | - Alex Teule
- Hereditary Cancer Program-Medical Oncology Service, Catalan Institute of Oncology, ICO-IDIBELL and CIBERONC, Barcelona, Spain
| | - Adriana Lasa
- Genetic Service, Hospital Sant Pau, Barcelona, Spain
| | | | - Gemma Llort
- Genetic Counseling Unit, Corporació Sanitària Parc Taulí, Barcelona, Spain
| | - Victoria Fernández
- Human Genetics Group, Spanish National Cancer Research Center (CNIO), Madrid, Spain
| | - Conxi Lázaro
- Hereditary Cancer Program, Catalan Institute of Oncology, ICO-IDIBELL and CIBERONC, Barcelona, Spain
| | - Miguel Urioste
- Center for Biomedical Network Research on Rare Diseases (CIBERER), Madrid, Spain.,Familial Cancer Clinical Unit, Spanish National Cancer Research Center (CNIO), Madrid, Spain
| | - Javier Benitez
- Human Genetics Group, Spanish National Cancer Research Center (CNIO), Madrid, Spain.,Center for Biomedical Network Research on Rare Diseases (CIBERER), Madrid, Spain
| |
Collapse
|
105
|
Structural insights into POT1-TPP1 interaction and POT1 C-terminal mutations in human cancer. Nat Commun 2017; 8:14929. [PMID: 28393832 PMCID: PMC5394241 DOI: 10.1038/ncomms14929] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 02/14/2017] [Indexed: 01/01/2023] Open
Abstract
Mammalian shelterin proteins POT1 and TPP1 form a stable heterodimer that protects chromosome ends and regulates telomerase-mediated telomere extension. However, how POT1 interacts with TPP1 remains unknown. Here we present the crystal structure of the C-terminal portion of human POT1 (POT1C) complexed with the POT1-binding motif of TPP1. The structure shows that POT1C contains two domains, a third OB fold and a Holliday junction resolvase-like domain. Both domains are essential for binding to TPP1. Notably, unlike the heart-shaped structure of ciliated protozoan Oxytricha nova TEBPα–β complex, POT1–TPP1 adopts an elongated V-shaped conformation. In addition, we identify several missense mutations in human cancers that disrupt the POT1C–TPP1 interaction, resulting in POT1 instability. POT1C mutants that bind TPP1 localize to telomeres but fail to repress a DNA damage response and inappropriate repair by A-NHEJ. Our results reveal that POT1 C terminus is essential to prevent initiation of genome instability permissive for tumorigenesis. Human telomeres are protected by a specialized shelterin complex composed of six proteins. Here the authors structurally characterize the interaction between the POT1-TPP1 shelterin component and identify mutations associated with genome instability and cancer that disrupt the POT1-TPP1 interaction.
Collapse
|
106
|
Martínez P, Blasco MA. Telomere-driven diseases and telomere-targeting therapies. J Cell Biol 2017; 216:875-887. [PMID: 28254828 PMCID: PMC5379954 DOI: 10.1083/jcb.201610111] [Citation(s) in RCA: 171] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 01/03/2017] [Accepted: 01/09/2017] [Indexed: 01/19/2023] Open
Abstract
Martínez and Blasco review the molecular mechanisms underlying diseases associated with telomere dysfunction, including telomeropathies, age-related disorders, and cancer. Current and future therapeutic strategies to treat and prevent these diseases, including preclinical development of telomere-targeted therapies using mouse models, are discussed. Telomeres, the protective ends of linear chromosomes, shorten throughout an individual’s lifetime. Telomere shortening is proposed to be a primary molecular cause of aging. Short telomeres block the proliferative capacity of stem cells, affecting their potential to regenerate tissues, and trigger the development of age-associated diseases. Mutations in telomere maintenance genes are associated with pathologies referred to as telomere syndromes, including Hoyeraal-Hreidarsson syndrome, dyskeratosis congenita, pulmonary fibrosis, aplastic anemia, and liver fibrosis. Telomere shortening induces chromosomal instability that, in the absence of functional tumor suppressor genes, can contribute to tumorigenesis. In addition, mutations in telomere length maintenance genes and in shelterin components, the protein complex that protects telomeres, have been found to be associated with different types of cancer. These observations have encouraged the development of therapeutic strategies to treat and prevent telomere-associated diseases, namely aging-related diseases, including cancer. Here we review the molecular mechanisms underlying telomere-driven diseases and highlight recent advances in the preclinical development of telomere-targeted therapies using mouse models.
Collapse
Affiliation(s)
- Paula Martínez
- Telomeres and Telomerase Group, Molecular Oncology Program, Spanish National Cancer Centre, Madrid E-28029, Spain
| | - Maria A Blasco
- Telomeres and Telomerase Group, Molecular Oncology Program, Spanish National Cancer Centre, Madrid E-28029, Spain
| |
Collapse
|
107
|
Pandita TK. Critical role of the POT1 OB domain in maintaining genomic stability. Oncogene 2016; 36:1908-1910. [PMID: 27869169 DOI: 10.1038/onc.2016.365] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Accepted: 08/19/2016] [Indexed: 01/14/2023]
Abstract
Oligonucleotide/oligosaccharide-binding (OB) domain-containing proteins have been identified as critical for telomere maintenance, DNA repair, transcription and other DNA metabolism processes. Protection of telomere 1 (POT1), a telomere binding protein, has an OB domain like single-strand binding protein (SSB1). In this issue of Oncogene, Gu et al. present evidence that POT1, like SSB1, is required to maintain genomic stability. This work, in conjunction with results from previous investigators, highlights the importance of POT1 in telomere metabolism. Inactivation of POT1 telomere protective functions in mouse models lacking p53 expression in the breast epithelium unleashes a torrent of DNA damage responses (DDRs) at the telomeres, culminating in karyotypic alterations with massive arrays of telomere fusions. Therefore, POT1 is not only required to promote telomere homeostasis, but also plays an essential role in maintaining a stable genome.
Collapse
Affiliation(s)
- T K Pandita
- Department of Radiation Oncology, The Houston Methodist Research Institute, Weill Cornell Medical College, The Houston Methodist Hospital, Houston, TX, USA
| |
Collapse
|
108
|
Gu P, Wang Y, Bisht KK, Wu L, Kukova L, Smith EM, Xiao Y, Bailey SM, Lei M, Nandakumar J, Chang S. Pot1 OB-fold mutations unleash telomere instability to initiate tumorigenesis. Oncogene 2016; 36:1939-1951. [PMID: 27869160 PMCID: PMC5383532 DOI: 10.1038/onc.2016.405] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Revised: 08/02/2016] [Accepted: 09/19/2016] [Indexed: 02/06/2023]
Abstract
Chromosomal aberrations are a hallmark of human cancers, with complex cytogenetic rearrangements leading to genetic changes permissive for cancer initiation and progression. Protection of Telomere 1 (POT1) is an essential component of the shelterin complex and functions to maintain chromosome stability by repressing the activation of aberrant DNA damage and repair responses at telomeres. Sporadic and familial mutations in the oligosaccharide-oligonucleotide (OB) folds of POT1 have been identified in many human cancers, but the mechanism underlying how hPOT1 mutations initiate tumorigenesis has remained unclear. Here we show that the human POT1’s OB-folds are essential for the protection of newly replicated telomeres. Oncogenic mutations in hPOT1 OB-fold fail to bind to ss telomeric DNA, eliciting a DNA damage response at telomeres that promote inappropriate chromosome fusions via the mutagenic alternative non-homologous end joining (A-NHEJ) pathway. hPOT1 mutations also result in telomere elongation and the formation of transplantable hematopoietic malignancies. Strikingly, conditional deletion of both mPot1a and p53 in mouse mammary epithelium resulted in development of highly invasive breast carcinomas and the formation of whole chromosomes containing massive arrays of telomeric fusions reminiscent of chromothripsis. Our results reveal that hPOT1 OB-folds are required to protect and prevent newly replicated telomeres from engaging in A-NHEJ mediated fusions that would otherwise promote genome instability to fuel tumorigenesis.
Collapse
Affiliation(s)
- P Gu
- Department of Laboratory Medicine, Yale University School of Medicine, New Haven, CT, USA
| | - Y Wang
- Department of Laboratory Medicine, Yale University School of Medicine, New Haven, CT, USA
| | - K K Bisht
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, USA.,Program in Chemical Biology, University of Michigan, Ann Arbor, MI, USA
| | - L Wu
- Department of GI Medical Oncology, UT MD Anderson Cancer Center, Houston, TX, USA
| | - L Kukova
- Department of Laboratory Medicine, Yale University School of Medicine, New Haven, CT, USA
| | - E M Smith
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, USA.,Program in Chemical Biology, University of Michigan, Ann Arbor, MI, USA
| | - Y Xiao
- Section of Hematology-Oncology, Department of Medicine and Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA
| | - S M Bailey
- Department of Environmental & Radiological Health Sciences, Colorado State University, Fort Collins, CO, USA
| | - M Lei
- National Center for Protein Science Shanghai, State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - J Nandakumar
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, USA.,Program in Chemical Biology, University of Michigan, Ann Arbor, MI, USA
| | - S Chang
- Department of Laboratory Medicine, Yale University School of Medicine, New Haven, CT, USA.,Department of Pathology, Yale University School of Medicine, New Haven, CT, USA.,Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT, USA
| |
Collapse
|
109
|
Boskovic J, Martinez-Gago J, Mendez-Pertuz M, Buscato A, Martinez-Torrecuadrada JL, Blasco MA. Molecular Architecture of Full-length TRF1 Favors Its Interaction with DNA. J Biol Chem 2016; 291:21829-21835. [PMID: 27563064 DOI: 10.1074/jbc.m116.744896] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 08/23/2016] [Indexed: 11/06/2022] Open
Abstract
Telomeres are specific DNA-protein structures found at both ends of eukaryotic chromosomes that protect the genome from degradation and from being recognized as double-stranded breaks. In vertebrates, telomeres are composed of tandem repeats of the TTAGGG sequence that are bound by a six-subunit complex called shelterin. Molecular mechanisms of telomere functions remain unknown in large part due to lack of structural data on shelterins, shelterin complex, and its interaction with the telomeric DNA repeats. TRF1 is one of the best studied shelterin components; however, the molecular architecture of the full-length protein remains unknown. We have used single-particle electron microscopy to elucidate the structure of TRF1 and its interaction with telomeric DNA sequence. Our results demonstrate that full-length TRF1 presents a molecular architecture that assists its interaction with telometic DNA and at the same time makes TRFH domains accessible to other TRF1 binding partners. Furthermore, our studies suggest hypothetical models on how other proteins as TIN2 and tankyrase contribute to regulate TRF1 function.
Collapse
Affiliation(s)
- Jasminka Boskovic
- From the Structural Biology and Biocomputing Programme, Electron Microscopy Unit,
| | - Jaime Martinez-Gago
- Structural Biology and Biocomputing Programme, Crystallography and Protein Engineering Unit, and
| | - Marinela Mendez-Pertuz
- Molecular Oncology Programme, Telomeres and Telomerase Group, Spanish National Cancer Research Centre (CNIO), 28029 Madrid, Spain
| | - Alberto Buscato
- From the Structural Biology and Biocomputing Programme, Electron Microscopy Unit
| | | | - Maria A Blasco
- Molecular Oncology Programme, Telomeres and Telomerase Group, Spanish National Cancer Research Centre (CNIO), 28029 Madrid, Spain
| |
Collapse
|
110
|
Sleat DE, Gedvilaite E, Zhang Y, Lobel P, Xing J. Analysis of large-scale whole exome sequencing data to determine the prevalence of genetically-distinct forms of neuronal ceroid lipofuscinosis. Gene 2016; 593:284-91. [PMID: 27553520 DOI: 10.1016/j.gene.2016.08.031] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Revised: 07/11/2016] [Accepted: 08/18/2016] [Indexed: 11/17/2022]
Abstract
The neuronal ceroid lipofuscinoses (NCLs) are a group of fatal, mostly recessive neurodegenerative lysosomal storage diseases. While clinically similar, they are genetically distinct and result from mutations in at least twelve different genes. Estimates of NCL incidence range from 0.6 to 14 per 100,000 live births but vary widely between populations and are influenced by whether patients are classified based upon clinical or genetic criteria. We investigated mutations in twelve NCL genes in ~61,000 individuals represented in the Exome Aggregation Consortium (ExAC) whole exome sequencing database. Variants were extracted from ExAC and pathogenic alleles were differentiated from neutral polymorphisms using annotated variant databases and missense mutation prediction tools. Carrier frequency was dependent on ethnicity, with the highest (1/75) observed for PPT1 in the Finnish. When data are adjusted for ethnic diversity within the USA, PPT1, TPP1 and CLN3 carrier frequencies were found to be the highest of the NCLs, each at ~1/500. Carrier frequencies calculated from ExAC correlated well with incidence estimated from numbers of living NCL patients in the US. In addition, the analysis identified numerous variants that are annotated as pathogenic in public repositories but have a predicted frequency that is not consistent with patient studies. These variants appear to be neutral polymorphisms that are reported as pathogenic without validation. Based upon literature reports, such alleles may be annotated in public databases as pathogenic and this propagates errors that can have clinical consequences.
Collapse
Affiliation(s)
- David E Sleat
- Center for Advanced Biotechnology and Medicine, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA; Department of Biochemistry and Molecular Biology, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA.
| | - Erika Gedvilaite
- Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA; Human Genetics Institute of New Jersey, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA.
| | - Yeting Zhang
- Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA; Human Genetics Institute of New Jersey, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA.
| | - Peter Lobel
- Center for Advanced Biotechnology and Medicine, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA; Department of Biochemistry and Molecular Biology, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA.
| | - Jinchuan Xing
- Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA; Human Genetics Institute of New Jersey, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA.
| |
Collapse
|
111
|
Lieberman PM. Retrotransposon-derived p53 binding sites enhance telomere maintenance and genome protection. Bioessays 2016; 38:943-9. [PMID: 27539745 DOI: 10.1002/bies.201600078] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Tumor suppressor protein 53 (p53) plays a central role in the control of genome stability, acting primarily through the transcriptional activation of stress-response genes. However, many p53 binding sites are located at genomic locations with no obvious regulatory-link to known stress-response genes. We recently discovered p53 binding sites within retrotransposon-derived elements in human and mouse subtelomeres. These retrotransposon-derived p53 binding sites protected chromosome ends through transcription activation of telomere repeat RNA, as well as through the direct modification of local chromatin structure in response to DNA damage. Based on these findings, I hypothesize that a class of p53 binding sites, including the retrotransposon-derived p53-sites found in subtlomeres, provide a primary function in genome stability by mounting a direct and local protective chromatin-response to DNA damage. I speculate that retrotransposon-derived p53 binding sites share features with telomere-repeats through an evolutionary drive to monitor and maintain genome integrity.
Collapse
|
112
|
Germ line mutations in shelterin complex genes are associated with familial chronic lymphocytic leukemia. Blood 2016; 128:2319-2326. [PMID: 27528712 DOI: 10.1182/blood-2016-01-695692] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Accepted: 08/08/2016] [Indexed: 12/30/2022] Open
Abstract
Chronic lymphocytic leukemia (CLL) can be familial; however, thus far no rare germ line disruptive alleles for CLL have been identified. We performed whole-exome sequencing of 66 CLL families, identifying 4 families where loss-of-function mutations in protection of telomeres 1 (POT1) co-segregated with CLL. The p.Tyr36Cys mutation is predicted to disrupt the interaction between POT1 and the telomeric overhang. The c.1164-1G>A splice-site, p.Gln358SerfsTer13 frameshift, and p.Gln376Arg missense mutations are likely to impact the interaction between POT1 and adrenocortical dysplasia homolog (ACD), which is a part of the telomere-capping shelterin complex. We also identified mutations in ACD (c.752-2A>C) and another shelterin component, telomeric repeat binding factor 2, interacting protein (p.Ala104Pro and p.Arg133Gln), in 3 CLL families. In a complementary analysis of 1083 cases and 5854 controls, the POT1 p.Gln376Arg variant, which has a global minor allele frequency of 0.0005, conferred a 3.61-fold increased risk of CLL (P = .009). This study further highlights telomere dysregulation as a key process in CLL development.
Collapse
|
113
|
Kim E, Ilic N, Shrestha Y, Zou L, Kamburov A, Zhu C, Yang X, Lubonja R, Tran N, Nguyen C, Lawrence MS, Piccioni F, Bagul M, Doench JG, Chouinard CR, Wu X, Hogstrom L, Natoli T, Tamayo P, Horn H, Corsello SM, Lage K, Root DE, Subramanian A, Golub TR, Getz G, Boehm JS, Hahn WC. Systematic Functional Interrogation of Rare Cancer Variants Identifies Oncogenic Alleles. Cancer Discov 2016; 6:714-26. [PMID: 27147599 PMCID: PMC4930723 DOI: 10.1158/2159-8290.cd-16-0160] [Citation(s) in RCA: 121] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Accepted: 04/26/2016] [Indexed: 12/12/2022]
Abstract
UNLABELLED Cancer genome characterization efforts now provide an initial view of the somatic alterations in primary tumors. However, most point mutations occur at low frequency, and the function of these alleles remains undefined. We have developed a scalable systematic approach to interrogate the function of cancer-associated gene variants. We subjected 474 mutant alleles curated from 5,338 tumors to pooled in vivo tumor formation assays and gene expression profiling. We identified 12 transforming alleles, including two in genes (PIK3CB, POT1) that have not been shown to be tumorigenic. One rare KRAS allele, D33E, displayed tumorigenicity and constitutive activation of known RAS effector pathways. By comparing gene expression changes induced upon expression of wild-type and mutant alleles, we inferred the activity of specific alleles. Because alleles found to be mutated only once in 5,338 tumors rendered cells tumorigenic, these observations underscore the value of integrating genomic information with functional studies. SIGNIFICANCE Experimentally inferring the functional status of cancer-associated mutations facilitates the interpretation of genomic information in cancer. Pooled in vivo screen and gene expression profiling identified functional variants and demonstrated that expression of rare variants induced tumorigenesis. Variant phenotyping through functional studies will facilitate defining key somatic events in cancer. Cancer Discov; 6(7); 714-26. ©2016 AACR.See related commentary by Cho and Collisson, p. 694This article is highlighted in the In This Issue feature, p. 681.
Collapse
Affiliation(s)
- Eejung Kim
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts. Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts
| | - Nina Ilic
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts. Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts
| | | | - Lihua Zou
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts. Cancer Center and Department of Pathology, Massachusetts General Hospital, Boston, Massachusetts
| | - Atanas Kamburov
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts. Cancer Center and Department of Pathology, Massachusetts General Hospital, Boston, Massachusetts
| | - Cong Zhu
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts
| | - Xiaoping Yang
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts
| | - Rakela Lubonja
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts
| | - Nancy Tran
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts
| | - Cindy Nguyen
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts
| | | | | | - Mukta Bagul
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts
| | - John G Doench
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts
| | | | - Xiaoyun Wu
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts
| | - Larson Hogstrom
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts
| | - Ted Natoli
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts
| | - Pablo Tamayo
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts. Department of Medicine, University of California, San Diego, La Jolla, California
| | - Heiko Horn
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts. Department of Surgery, Massachusetts General Hospital, Boston, Massachusetts
| | - Steven M Corsello
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts. Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts
| | - Kasper Lage
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts. Department of Surgery, Massachusetts General Hospital, Boston, Massachusetts
| | - David E Root
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts
| | | | - Todd R Golub
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts. Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts
| | - Gad Getz
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts. Cancer Center and Department of Pathology, Massachusetts General Hospital, Boston, Massachusetts
| | - Jesse S Boehm
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts
| | - William C Hahn
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts. Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts.
| |
Collapse
|
114
|
Chubb D, Broderick P, Dobbins SE, Frampton M, Kinnersley B, Penegar S, Price A, Ma YP, Sherborne AL, Palles C, Timofeeva MN, Bishop DT, Dunlop MG, Tomlinson I, Houlston RS. Rare disruptive mutations and their contribution to the heritable risk of colorectal cancer. Nat Commun 2016; 7:11883. [PMID: 27329137 PMCID: PMC4917884 DOI: 10.1038/ncomms11883] [Citation(s) in RCA: 108] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Accepted: 05/09/2016] [Indexed: 12/30/2022] Open
Abstract
Colorectal cancer (CRC) displays a complex pattern of inheritance. It is postulated that much of the missing heritability of CRC is enshrined in high-impact rare alleles, which are mechanistically and clinically important. In this study, we assay the impact of rare germline mutations on CRC, analysing high-coverage exome sequencing data on 1,006 early-onset familial CRC cases and 1,609 healthy controls, with additional sequencing and array data on up to 5,552 cases and 6,792 controls. We identify highly penetrant rare mutations in 16% of familial CRC. Although the majority of these reside in known genes, we identify POT1, POLE2 and MRE11 as candidate CRC genes. We did not identify any coding low-frequency alleles (1-5%) with moderate effect. Our study clarifies the genetic architecture of CRC and probably discounts the existence of further major high-penetrance susceptibility genes, which individually account for >1% of the familial risk. Our results inform future study design and provide a resource for contextualizing the impact of new CRC genes.
Collapse
Affiliation(s)
- Daniel Chubb
- Division of Genetics and Epidemiology, The Institute of Cancer Research, London SM2 5NG, UK
| | - Peter Broderick
- Division of Genetics and Epidemiology, The Institute of Cancer Research, London SM2 5NG, UK
| | - Sara E. Dobbins
- Division of Genetics and Epidemiology, The Institute of Cancer Research, London SM2 5NG, UK
| | - Matthew Frampton
- Division of Genetics and Epidemiology, The Institute of Cancer Research, London SM2 5NG, UK
| | - Ben Kinnersley
- Division of Genetics and Epidemiology, The Institute of Cancer Research, London SM2 5NG, UK
| | - Steven Penegar
- Division of Genetics and Epidemiology, The Institute of Cancer Research, London SM2 5NG, UK
| | - Amy Price
- Division of Genetics and Epidemiology, The Institute of Cancer Research, London SM2 5NG, UK
| | - Yussanne P. Ma
- Division of Genetics and Epidemiology, The Institute of Cancer Research, London SM2 5NG, UK
| | - Amy L. Sherborne
- Division of Genetics and Epidemiology, The Institute of Cancer Research, London SM2 5NG, UK
| | - Claire Palles
- Molecular and Population Genetics Laboratory, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Maria N. Timofeeva
- Centre for Population Health Sciences, University of Edinburgh, Edinburgh EH8 9AG, UK
| | - D. Timothy Bishop
- Section of Epidemiology and Biostatistics, Leeds Institute of Cancer and Pathology, University of Leeds, St James's University Hospital, Leeds LS9 7TF, UK
| | - Malcolm G. Dunlop
- Centre for Population Health Sciences, University of Edinburgh, Edinburgh EH8 9AG, UK
| | - Ian Tomlinson
- Molecular and Population Genetics Laboratory, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Richard S. Houlston
- Division of Genetics and Epidemiology, The Institute of Cancer Research, London SM2 5NG, UK
- Division of Pathology, The Institute of Cancer Research, London SM2 5NG, UK
| |
Collapse
|
115
|
Pinzaru AM, Hom RA, Beal A, Phillips AF, Ni E, Cardozo T, Nair N, Choi J, Wuttke DS, Sfeir A, Denchi EL. Telomere Replication Stress Induced by POT1 Inactivation Accelerates Tumorigenesis. Cell Rep 2016; 15:2170-2184. [PMID: 27239034 PMCID: PMC6145145 DOI: 10.1016/j.celrep.2016.05.008] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Revised: 02/19/2016] [Accepted: 04/22/2016] [Indexed: 01/05/2023] Open
Abstract
Genome sequencing studies have revealed a number of cancer-associated mutations in the telomerebinding factor POT1. Here, we show that when combined with p53 deficiency, depletion of murine POT1a in common lymphoid progenitor cells fosters genetic instability, accelerates the onset, and increases the severity of T cell lymphomas. In parallel, we examined human and mouse cells carrying POT1 mutations found in cutaneous T cell lymphoma (CTCL) patients. Inhibition of POT1 activates ATRdependent DNA damage signaling and induces telomere fragility, replication fork stalling, and telomere elongation. Our data suggest that these phenotypes are linked to impaired CST (CTC1-STN1-TEN1) function at telomeres. Lastly, we show that proliferation of cancer cells lacking POT1 is enabled by the attenuation of the ATR kinase pathway. These results uncover a role for defective telomere replication during tumorigenesis. Pinzaru et al. define a role for POT1 inactivation in the onset of thymic lymphomas. Inhibition of POT1 causes replication defects at telomeres resulting in telomere fragility, replication fork stalling, and genome instability. These results suggest a role of defective telemore replication during tumorigenesis
Collapse
Affiliation(s)
- Alexandra M Pinzaru
- Department of Cell Biology, Skirball Institute of Biomolecular Medicine, NYU School of Medicine, New York, NY 10016, USA
| | - Robert A Hom
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309, USA
| | - Angela Beal
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Aaron F Phillips
- Department of Cell Biology, Skirball Institute of Biomolecular Medicine, NYU School of Medicine, New York, NY 10016, USA
| | - Eric Ni
- Department of Biochemistry and Molecular Pharmacology, NYU School of Medicine, New York, NY 10016, USA
| | - Timothy Cardozo
- Department of Biochemistry and Molecular Pharmacology, NYU School of Medicine, New York, NY 10016, USA
| | - Nidhi Nair
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Jaehyuk Choi
- Departments of Dermatology and Biochemistry and Molecular Genetics, Northwestern University, Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Deborah S Wuttke
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309, USA
| | - Agnel Sfeir
- Department of Cell Biology, Skirball Institute of Biomolecular Medicine, NYU School of Medicine, New York, NY 10016, USA.
| | - Eros Lazzerini Denchi
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA.
| |
Collapse
|
116
|
Stop pulling my strings - what telomeres taught us about the DNA damage response. Nat Rev Mol Cell Biol 2016; 17:364-78. [PMID: 27165790 DOI: 10.1038/nrm.2016.43] [Citation(s) in RCA: 123] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Mammalian cells have evolved specialized mechanisms to sense and repair double-strand breaks (DSBs) to maintain genomic stability. However, in certain cases, the activity of these pathways can lead to aberrant DNA repair, genomic instability and tumorigenesis. One such case is DNA repair at the natural ends of linear chromosomes, known as telomeres, which can lead to chromosome-end fusions. Here, we review data obtained over the past decade and discuss the mechanisms that protect mammalian chromosome ends from the DNA damage response. We also discuss how telomere research has helped to uncover key steps in DSB repair. Last, we summarize how dysfunctional telomeres and the ensuing genomic instability drive the progression of cancer.
Collapse
|
117
|
Jones M, Bisht K, Savage SA, Nandakumar J, Keegan CE, Maillard I. The shelterin complex and hematopoiesis. J Clin Invest 2016; 126:1621-9. [PMID: 27135879 DOI: 10.1172/jci84547] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Mammalian chromosomes terminate in stretches of repetitive telomeric DNA that act as buffers to avoid loss of essential genetic information during end-replication. A multiprotein complex known as shelterin prevents recognition of telomeric sequences as sites of DNA damage. Telomere erosion contributes to human diseases ranging from BM failure to premature aging syndromes and cancer. The role of shelterin telomere protection is less understood. Mutations in genes encoding the shelterin proteins TRF1-interacting nuclear factor 2 (TIN2) and adrenocortical dysplasia homolog (ACD) were identified in dyskeratosis congenita, a syndrome characterized by somatic stem cell dysfunction in multiple organs leading to BM failure and other pleiotropic manifestations. Here, we introduce the biochemical features and in vivo effects of individual shelterin proteins, discuss shelterin functions in hematopoiesis, and review emerging knowledge implicating the shelterin complex in hematological disorders.
Collapse
|
118
|
Candidate driver genes involved in genome maintenance and DNA repair in Sézary syndrome. Blood 2016; 127:3387-97. [PMID: 27121473 DOI: 10.1182/blood-2016-02-699843] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 04/13/2016] [Indexed: 12/13/2022] Open
Abstract
Sézary syndrome (SS) is a leukemic variant of cutaneous T-cell lymphoma (CTCL) and represents an ideal model for study of T-cell transformation. We describe whole-exome and single-nucleotide polymorphism array-based copy number analyses of CD4(+) tumor cells from untreated patients at diagnosis and targeted resequencing of 101 SS cases. A total of 824 somatic nonsynonymous gene variants were identified including indels, stop-gain/loss, splice variants, and recurrent gene variants indicative of considerable molecular heterogeneity. Driver genes identified using MutSigCV include POT1, which has not been previously reported in CTCL; and TP53 and DNMT3A, which were also identified consistent with previous reports. Mutations in PLCG1 were detected in 11% of tumors including novel variants not previously described in SS. This study is also the first to show BRCA2 defects in a significant proportion (14%) of SS tumors. Aberrations in PRKCQ were found to occur in 20% of tumors highlighting selection for activation of T-cell receptor/NF-κB signaling. A complex but consistent pattern of copy number variants (CNVs) was detected and many CNVs involved genes identified as putative drivers. Frequent defects involving the POT1 and ATM genes responsible for telomere maintenance were detected and may contribute to genomic instability in SS. Genomic aberrations identified were enriched for genes implicated in cell survival and fate, specifically PDGFR, ERK, JAK STAT, MAPK, and TCR/NF-κB signaling; epigenetic regulation (DNMT3A, ASLX3, TET1-3); and homologous recombination (RAD51C, BRCA2, POLD1). This study now provides the basis for a detailed functional analysis of malignant transformation of mature T cells and improved patient stratification and treatment.
Collapse
|
119
|
Sarkar J, Liu Y. Fanconi anemia proteins in telomere maintenance. DNA Repair (Amst) 2016; 43:107-12. [PMID: 27118469 DOI: 10.1016/j.dnarep.2016.02.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 02/03/2016] [Indexed: 11/15/2022]
Abstract
Mammalian chromosome ends are protected by nucleoprotein structures called telomeres. Telomeres ensure genome stability by preventing chromosome termini from being recognized as DNA damage. Telomere length homeostasis is inevitable for telomere maintenance because critical shortening or over-lengthening of telomeres may lead to DNA damage response or delay in DNA replication, and hence genome instability. Due to their repetitive DNA sequence, unique architecture, bound shelterin proteins, and high propensity to form alternate/secondary DNA structures, telomeres are like common fragile sites and pose an inherent challenge to the progression of DNA replication, repair, and recombination apparatus. It is conceivable that longer the telomeres are, greater is the severity of such challenges. Recent studies have linked excessively long telomeres with increased tumorigenesis. Here we discuss telomere abnormalities in a rare recessive chromosomal instability disorder called Fanconi Anemia and the role of the Fanconi Anemia pathway in telomere biology. Reports suggest that Fanconi Anemia proteins play a role in maintaining long telomeres, including processing telomeric joint molecule intermediates. We speculate that ablation of the Fanconi Anemia pathway would lead to inadequate aberrant structural barrier resolution at excessively long telomeres, thereby causing replicative burden on the cell.
Collapse
Affiliation(s)
- Jaya Sarkar
- Laboratory of Molecular Gerontology, National Institute on Aging/National Institutes of Health, 251 Bayview Blvd, Baltimore, MD 21044, USA
| | - Yie Liu
- Laboratory of Molecular Gerontology, National Institute on Aging/National Institutes of Health, 251 Bayview Blvd, Baltimore, MD 21044, USA.
| |
Collapse
|
120
|
|