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Martin A, Schabort J, Bartke-Croughan R, Tran S, Preetham A, Lu R, Ho R, Gao J, Jenkins S, Boyle J, Ghanim GE, Jagota M, Song YS, Li H, Hockemeyer D. Dissecting the oncogenic mechanisms of POT1 cancer mutations through deep scanning mutagenesis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.08.19.608636. [PMID: 39229243 PMCID: PMC11370387 DOI: 10.1101/2024.08.19.608636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/05/2024]
Abstract
Mutations in the shelterin protein POT1 are associated with diverse cancers, but their role in cancer progression remains unclear. To resolve this, we performed deep scanning mutagenesis in POT1 locally haploid human stem cells to assess the impact of POT1 variants on cellular viability and cancer-associated telomeric phenotypes. Though POT1 is essential, frame-shift mutants are rescued by chemical ATR inhibition, indicating that POT1 is not required for telomere replication or lagging strand synthesis. In contrast, a substantial fraction of clinically-validated pathogenic mutations support normal cellular proliferation, but still drive ATR-dependent telomeric DNA damage signaling and ATR-independent telomere elongation. Moreover, this class of cancer-associated POT1 variants elongates telomeres more rapidly than POT1 frame-shifts, indicating they actively drive oncogenesis and are not simple loss-of-function mutations.
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Acs-Szabo L, Papp LA, Miklos I. Understanding the molecular mechanisms of human diseases: the benefits of fission yeasts. MICROBIAL CELL (GRAZ, AUSTRIA) 2024; 11:288-311. [PMID: 39104724 PMCID: PMC11299203 DOI: 10.15698/mic2024.08.833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Revised: 07/04/2024] [Accepted: 07/10/2024] [Indexed: 08/07/2024]
Abstract
The role of model organisms such as yeasts in life science research is crucial. Although the baker's yeast (Saccharomyces cerevisiae) is the most popular model among yeasts, the contribution of the fission yeasts (Schizosaccharomyces) to life science is also indisputable. Since both types of yeasts share several thousands of common orthologous genes with humans, they provide a simple research platform to investigate many fundamental molecular mechanisms and functions, thereby contributing to the understanding of the background of human diseases. In this review, we would like to highlight the many advantages of fission yeasts over budding yeasts. The usefulness of fission yeasts in virus research is shown as an example, presenting the most important research results related to the Human Immunodeficiency Virus Type 1 (HIV-1) Vpr protein. Besides, the potential role of fission yeasts in the study of prion biology is also discussed. Furthermore, we are keen to promote the uprising model yeast Schizosaccharomyces japonicus, which is a dimorphic species in the fission yeast genus. We propose the hyphal growth of S. japonicus as an unusual opportunity as a model to study the invadopodia of human cancer cells since the two seemingly different cell types can be compared along fundamental features. Here we also collect the latest laboratory protocols and bioinformatics tools for the fission yeasts to highlight the many possibilities available to the research community. In addition, we present several limiting factors that everyone should be aware of when working with yeast models.
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Affiliation(s)
- Lajos Acs-Szabo
- Department of Genetics and Applied Microbiology, Faculty of Science and Technology, University of DebrecenDebrecen, 4032Hungary
| | - Laszlo Attila Papp
- Department of Genetics and Applied Microbiology, Faculty of Science and Technology, University of DebrecenDebrecen, 4032Hungary
| | - Ida Miklos
- Department of Genetics and Applied Microbiology, Faculty of Science and Technology, University of DebrecenDebrecen, 4032Hungary
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3
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Andreotti V, Vanni I, Pastorino L, Ghiorzo P, Bruno W. Germline POT1 Variants: A Critical Perspective on POT1 Tumor Predisposition Syndrome. Genes (Basel) 2024; 15:104. [PMID: 38254993 PMCID: PMC10815363 DOI: 10.3390/genes15010104] [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: 12/18/2023] [Revised: 01/10/2024] [Accepted: 01/13/2024] [Indexed: 01/24/2024] Open
Abstract
The Protection of Telomere 1 (POT1) gene was identified as a melanoma predisposition candidate nearly 10 years ago. Thereafter, various cancers have been proposed as associated with germline POT1 variants in the context of the so-called POT1 Predisposition Tumor Syndrome (POT1-TPD). While the key role, and related risks, of the alterations in POT1 in melanoma are established, the correlation between germline POT1 variants and the susceptibility to other cancers partially lacks evidence, due also to the rarity of POT1-TPD. Issues range from the absence of functional or segregation studies to biased datasets or the need for a revised classification of variants. Furthermore, a proposal of a surveillance protocol related to the cancers associated with POT1 pathogenic variants requires reliable data to avoid an excessive, possibly unjustified, burden for POT1 variant carriers. We propose a critical perspective regarding data published over the last 10 years that correlate POT1 variants to various types of cancer, other than cutaneous melanoma, to offer food for thought for the specialists who manage cancer predisposition syndromes and to stimulate a debate on the grey areas that have been exposed.
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Affiliation(s)
- Virginia Andreotti
- Genetics of Rare Cancers, IRCCS Ospedale Policlinico San Martino, Largo Rosanna Benzi 10, 16132 Genoa, Italy; (V.A.); (I.V.); (L.P.); (P.G.)
| | - Irene Vanni
- Genetics of Rare Cancers, IRCCS Ospedale Policlinico San Martino, Largo Rosanna Benzi 10, 16132 Genoa, Italy; (V.A.); (I.V.); (L.P.); (P.G.)
| | - Lorenza Pastorino
- Genetics of Rare Cancers, IRCCS Ospedale Policlinico San Martino, Largo Rosanna Benzi 10, 16132 Genoa, Italy; (V.A.); (I.V.); (L.P.); (P.G.)
- Department of Internal Medicine and Medical Specialties (DiMI), University of Genoa, V.le Benedetto XV 6, 16132 Genoa, Italy
| | - Paola Ghiorzo
- Genetics of Rare Cancers, IRCCS Ospedale Policlinico San Martino, Largo Rosanna Benzi 10, 16132 Genoa, Italy; (V.A.); (I.V.); (L.P.); (P.G.)
- Department of Internal Medicine and Medical Specialties (DiMI), University of Genoa, V.le Benedetto XV 6, 16132 Genoa, Italy
| | - William Bruno
- Genetics of Rare Cancers, IRCCS Ospedale Policlinico San Martino, Largo Rosanna Benzi 10, 16132 Genoa, Italy; (V.A.); (I.V.); (L.P.); (P.G.)
- Department of Internal Medicine and Medical Specialties (DiMI), University of Genoa, V.le Benedetto XV 6, 16132 Genoa, Italy
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4
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Jensen MR, Jelsig AM, Gerdes AM, Hölmich LR, Kainu KH, Lorentzen HF, Hansen MH, Bak M, Johansson PA, Hayward NK, Van Overeem Hansen T, Wadt KA. TINF2 is a major susceptibility gene in Danish patients with multiple primary melanoma. HGG ADVANCES 2023; 4:100225. [PMID: 37646013 PMCID: PMC10461021 DOI: 10.1016/j.xhgg.2023.100225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 07/19/2023] [Indexed: 09/01/2023] Open
Abstract
TINF2 encodes the TINF2 protein, which is a subunit in the shelterin complex critical for telomere regulation. Three recent studies have associated six truncating germline variants in TINF2 that have previously been associated with a cancer predisposition syndrome (CPS) caused by elongation of the telomeres. This has added TINF2 to the long telomere syndrome genes, together with other telomere maintenance genes such as ACD, POT1, TERF2IP, and TERT. We report a clinical study of 102 Danish patients with multiple primary melanoma (MPM) in which a germline truncating variant in TINF2 (p.(Arg265Ter)) was identified in four unrelated participants. The telomere lengths of three variant carriers were >90% percentile. In a routine diagnostic setting, the variant was identified in two more families, including an additional MPM patient and monozygotic twins with thyroid cancer and other cancer types. A total of 10 individuals from six independent families were confirmed carriers, all with cancer history, predominantly melanoma. Our findings suggest a major role of TINF2 in Danish patients with MPM. In addition to melanoma, other cancers in the six families include thyroid, renal, breast, and sarcoma, supporting a CPS in which melanoma, thyroid cancer, and sarcoma predominate. Further studies are needed to establish the full spectrum of associated cancer types and characterize lifetime cancer risk in carriers.
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Affiliation(s)
- Marlene Richter Jensen
- Department of Clinical Genetics, Copenhagen University Hospital Rigshospitalet, 2100 Copenhagen, Denmark
| | - Anne Marie Jelsig
- Department of Clinical Genetics, Copenhagen University Hospital Rigshospitalet, 2100 Copenhagen, Denmark
| | - Anne-Marie Gerdes
- Department of Clinical Genetics, Copenhagen University Hospital Rigshospitalet, 2100 Copenhagen, Denmark
| | - Lisbet Rosenkrantz Hölmich
- Department of Plastic and Reconstructive Surgery, Herlev and Gentofte Hospital, 2730 Herlev, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Kati Hannele Kainu
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Department of Dermatology and Allergology, Herlev and Gentofte Hospital, 2900 Gentofte, Denmark
| | | | | | - Mads Bak
- Department of Clinical Genetics, Copenhagen University Hospital Rigshospitalet, 2100 Copenhagen, Denmark
| | | | | | - Thomas Van Overeem Hansen
- Department of Clinical Genetics, Copenhagen University Hospital Rigshospitalet, 2100 Copenhagen, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Karin A.W. Wadt
- Department of Clinical Genetics, Copenhagen University Hospital Rigshospitalet, 2100 Copenhagen, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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5
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Li Q, Wang X, Liu J, Wu L, Xu S. POT1 involved in telomeric DNA damage repair and genomic stability of cervical cancer cells in response to radiation. MUTATION RESEARCH. GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2023; 891:503670. [PMID: 37770150 DOI: 10.1016/j.mrgentox.2023.503670] [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: 04/30/2023] [Revised: 07/25/2023] [Accepted: 08/05/2023] [Indexed: 10/03/2023]
Abstract
Though telomeres play a crucial role in maintaining genomic stability in cancer cells and have emerged as attractive therapeutic targets in anticancer therapy, the relationship between telomere dysfunction and genomic instability induced by irradiation is still unclear. In this study, we identified that protection of telomeres 1 (POT1), a single-stranded DNA (ssDNA)-binding protein, was upregulated in γ-irradiated HeLa cells and in cancer patients who exhibit radiation tolerance. Knockdown of POT1 delayed the repair of radiation-induced telomeric DNA damage which was associated with enhanced H3K9 trimethylation and enhanced the radiosensitivity of HeLa cells. The depletion of POT1 also resulted in significant genomic instability, by showing a significant increase in end-to-end chromosomal fusions, and the formation of anaphase bridges and micronuclei. Furthermore, knockdown of POT1 disturbed telomerase recruitment to telomere, and POT1 could interact with phosphorylated ATM (p-ATM) and POT1 depletion decreased the levels of p-ATM induced by irradiation, suggesting that POT1 could regulate the telomerase recruitment to telomeres to repair irradiation-induced telomeric DNA damage of HeLa cells through interactions with p-ATM. The enhancement of radiosensitivity in cancer cells can be achieved through the combination of POT1 and telomerase inhibitors, presenting a potential approach for radiotherapy in cancer treatment.
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Affiliation(s)
- Qian Li
- School of Environmental Science and Optoelectronic Technology, University of Science and Technology of China, Hefei, Anhui 230026, PR China
| | - Xiaofei Wang
- School of Biology, Food and Environment, Hefei University, Hefei 230601, PR China
| | - Jie Liu
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Institutes of Physical Science and Information Technology, Anhui University, Hefei, Anhui 230601, PR China
| | - Lijun Wu
- School of Environmental Science and Optoelectronic Technology, University of Science and Technology of China, Hefei, Anhui 230026, PR China; Information Materials and Intelligent Sensing Laboratory of Anhui Province, Institutes of Physical Science and Information Technology, Anhui University, Hefei, Anhui 230601, PR China.
| | - Shengmin Xu
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Institutes of Physical Science and Information Technology, Anhui University, Hefei, Anhui 230601, PR China.
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Takasugi T, Gu P, Liang F, Staco I, Chang S. Pot1b -/- tumors activate G-quadruplex-induced DNA damage to promote telomere hyper-elongation. Nucleic Acids Res 2023; 51:9227-9247. [PMID: 37560909 PMCID: PMC10516629 DOI: 10.1093/nar/gkad648] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 07/14/2023] [Accepted: 07/22/2023] [Indexed: 08/11/2023] Open
Abstract
Malignant cancers must activate telomere maintenance mechanisms to achieve replicative immortality. Mutations in the human Protection of Telomeres 1 (POT1) gene are frequently detected in cancers with abnormally long telomeres, suggesting that the loss of POT1 function disrupts the regulation of telomere length homeostasis to promote telomere elongation. However, our understanding of the mechanisms leading to elongated telomeres remains incomplete. The mouse genome encodes two POT1 proteins, POT1a and POT1b possessing separation of hPOT1 functions. We performed serial transplantation of Pot1b-/- sarcomas to better understand the role of POT1b in regulating telomere length maintenance. While early-generation Pot1b-/- sarcomas initially possessed shortened telomeres, late-generation Pot1b-/- cells display markedly hyper-elongated telomeres that were recognized as damaged DNA by the Replication Protein A (RPA) complex. The RPA-ATR-dependent DNA damage response at telomeres promotes telomerase recruitment to facilitate telomere hyper-elongation. POT1b, but not POT1a, was able to unfold G-quadruplex present in hyper-elongated telomeres to repress the DNA damage response. Our findings demonstrate that the repression of the RPA-ATR DDR is conserved between POT1b and human POT1, suggesting that similar mechanisms may underly the phenotypes observed in human cancers harboring human POT1 mutations.
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Affiliation(s)
- Taylor Takasugi
- Department of Laboratory Medicine, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Peili Gu
- Department of Laboratory Medicine, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Fengshan Liang
- Department of Laboratory Medicine, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Isabelle Staco
- Department of Laboratory Medicine, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Sandy Chang
- Department of Laboratory Medicine, Yale University School of Medicine, New Haven, CT 06520, USA
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520, USA
- Department of Pathology, Yale University School of Medicine, New Haven, CT 06520, USA
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7
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Zade NH, Khattar E. POT1 mutations cause differential effects on telomere length leading to opposing disease phenotypes. J Cell Physiol 2023; 238:1237-1255. [PMID: 37183325 DOI: 10.1002/jcp.31034] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2023] [Revised: 03/28/2023] [Accepted: 04/17/2023] [Indexed: 05/16/2023]
Abstract
The protection of telomere protein (POT1) is a telomere-binding protein and is an essential component of the six-membered shelterin complex, which is associated with the telomeres. POT1 directly binds to the 3' single-stranded telomeric overhang and prevents the activation of DNA damage response at telomeres thus preventing the telomere-telomere fusions and genomic instability. POT1 also plays a pivotal role in maintaining telomere length by regulating telomerase-mediated telomere elongation. Mutations in POT1 proteins result in three different telomere phenotypes, which include long, short, or aberrant telomere length. Long telomeres predispose individuals to cancer, while short or aberrant telomere phenotypes result in pro-aging diseases referred to as telomeropathies. Here, we review the function of POT1 proteins in telomere length hemostasis and how the spectrum of mutations reported in POT1 can be segregated toward developing very distinct disease phenotypes of cancer and telomeropathies.
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Affiliation(s)
- Nikita Harish Zade
- Sunandan Divatia School of Science, SVKM's NMIMS (Deemed to be) University, Mumbai, India
| | - Ekta Khattar
- Sunandan Divatia School of Science, SVKM's NMIMS (Deemed to be) University, Mumbai, India
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8
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Rao X, Xue J, Du Y, Zhou Z, Lu Y. Prognosis Prediction of Lung Adenocarcinoma Patients Based on Molecular Subgroups of DNA Methylation. Appl Immunohistochem Mol Morphol 2023; 31:255-265. [PMID: 36877181 DOI: 10.1097/pai.0000000000001114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 11/13/2022] [Indexed: 03/07/2023]
Abstract
Lung adenocarcinoma (LUAD) is a malignant tumor with high mortality. At present, the clinicopathologic feature is the main breakthrough to assess the prognosis of LUAD patients. However, in most cases, the results are less than satisfactory. Cox regression analysis was conducted in this study to obtain methylation sites with significant prognostic relevance based on mRNA expression, DNA methylation data, and clinical data of LUAD from The Cancer Genome Atlas Program database. LUAD patients were grouped into 4 subtypes according to different methylation levels using K-means consensus cluster analysis. By survival analysis, patients were grouped into high-methylation and low-methylation groups. Later, 895 differentially expressed genes (DEGs) were obtained. Eight optimal methylation signature genes associated with prognosis were screened by Cox regression analysis, and a risk assessment model was constructed based on these genes. Samples were then classified into high-risk and low-risk groups depending on the risk assessment model, and prognostic, predictive ability was assessed using survival and receiver operating characteristic (ROC) curves. The results showed that this risk model had a great efficacy in predicting the prognosis of patients, and it was, therefore, able to be an independent prognostic factor. At last, the enrichment analysis demonstrated that the signaling pathways, including cell cycle, homologous recombination, P53 signaling pathway, DNA replication, pentose phosphate pathway, and glycolysis gluconeogenesis were remarkably activated in the high-risk group. In general, we construct an 8-gene model based on DNA methylation molecular subtypes by a series of bioinformatics methods, which can provide new insights for predicting the prognosis of patients with LUAD.
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Affiliation(s)
- Xiao Rao
- Department of Cardio-Thoracic Surgery, Affiliated Jinhua Hospital, Zhejiang University School of Medicine, Jinhua, China
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9
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Telomerase: A prominent oncological target for development of chemotherapeutic agents. Eur J Med Chem 2023; 249:115121. [PMID: 36669398 DOI: 10.1016/j.ejmech.2023.115121] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 12/26/2022] [Accepted: 01/11/2023] [Indexed: 01/15/2023]
Abstract
Telomerase is a ribonucleoprotein (RNP) responsible for the maintenance of chromosomal integrity by stabilizing telomere length. Telomerase is a widely expressed hallmark responsible for replicative immortality in 80-90% of malignant tumors. Cancer cells produce telomerase which prevents telomere shortening by adding telomeres sequences beyond Hayflick's limit; which enables them to divide uncontrollably. The activity of telomerase is relatively low in somatic cells and absent in normal cells, but the re-activation of this RNP in normal cells suppresses p53 activity which leads to the avoidance of senescence causing malignancy. Here, we have focused explicitly on various anti-telomerase therapies and telomerase-inhibiting molecules for the treatment of cancer. We have covered molecules that are reported in developmental, preclinical, and clinical trial stages as potent telomerase inhibitors. Apart from chemotherapy, we have also included details of immunotherapy, gene therapy, G-quadruplex stabilizers, and HSP-90 inhibitors. The purpose of this work is to discuss the challenges behind the development of novel telomerase inhibitors and to identify various perspectives for designing anti-telomerase compounds.
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10
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Wolf SE, Sanders TL, Beltran SE, Rosvall KA. The telomere regulatory gene POT1 responds to stress and predicts performance in nature: Implications for telomeres and life history evolution. Mol Ecol 2022; 31:6155-6171. [PMID: 34674335 DOI: 10.1111/mec.16237] [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: 10/23/2019] [Revised: 09/25/2021] [Accepted: 10/12/2021] [Indexed: 02/02/2023]
Abstract
Telomeres are emerging as correlates of fitness-related traits and may be important mediators of ecologically relevant variation in life history strategies. Growing evidence suggests that telomere dynamics can be more predictive of performance than length itself, but very little work considers how telomere regulatory mechanisms respond to environmental challenges or influence performance in nature. Here, we combine observational and experimental data sets from free-living tree swallows (Tachycineta bicolor) to assess how performance is predicted by the telomere regulatory gene POT1, which encodes a shelterin protein that sterically blocks telomerase from repairing the telomere. First, we show that lower POT1 gene expression in the blood was associated with higher female quality, that is, earlier breeding and heavier body mass. We next challenged mothers with an immune stressor (lipopolysaccharide injection) that led to "sickness" in mothers and 24 h of food restriction in their offspring. While POT1 did not respond to maternal injection, females with lower constitutive POT1 gene expression were better able to maintain feeding rates following treatment. Maternal injection also generated a 1-day stressor for chicks, which responded with lower POT1 gene expression and elongated telomeres. Other putatively stress-responsive mechanisms (i.e., glucocorticoids, antioxidants) showed marginal responses in stress-exposed chicks. Model comparisons indicated that POT1 mRNA abundance was a largely better predictor of performance than telomere dynamics, indicating that telomere regulators may be powerful modulators of variation in life history strategies.
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Affiliation(s)
- Sarah E Wolf
- Department of Biology, Indiana University, Bloomington, Indiana, USA.,Center for the Integrative Study of Animal Behavior, Indiana University, Bloomington, Indiana, USA
| | - Tiana L Sanders
- Center for the Integrative Study of Animal Behavior, Indiana University, Bloomington, Indiana, USA
| | - Sol E Beltran
- Center for the Integrative Study of Animal Behavior, Indiana University, Bloomington, Indiana, USA
| | - Kimberly A Rosvall
- Department of Biology, Indiana University, Bloomington, Indiana, USA.,Center for the Integrative Study of Animal Behavior, Indiana University, Bloomington, Indiana, USA
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11
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Liddiard K, Aston-Evans AN, Cleal K, Hendrickson E, Baird D. POLQ suppresses genome instability and alterations in DNA repeat tract lengths. NAR Cancer 2022; 4:zcac020. [PMID: 35774233 PMCID: PMC9241439 DOI: 10.1093/narcan/zcac020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 05/19/2022] [Accepted: 06/10/2022] [Indexed: 11/26/2022] Open
Abstract
DNA polymerase theta (POLQ) is a principal component of the alternative non-homologous end-joining (ANHEJ) DNA repair pathway that ligates DNA double-strand breaks. Utilizing independent models of POLQ insufficiency during telomere-driven crisis, we found that POLQ - /- cells are resistant to crisis-induced growth deceleration despite sustaining inter-chromosomal telomere fusion frequencies equivalent to wild-type (WT) cells. We recorded longer telomeres in POLQ - / - than WT cells pre- and post-crisis, notwithstanding elevated total telomere erosion and fusion rates. POLQ - /- cells emerging from crisis exhibited reduced incidence of clonal gross chromosomal abnormalities in accordance with increased genetic heterogeneity. High-throughput sequencing of telomere fusion amplicons from POLQ-deficient cells revealed significantly raised frequencies of inter-chromosomal fusions with correspondingly depreciated intra-chromosomal recombinations. Long-range interactions culminating in telomere fusions with centromere alpha-satellite repeats, as well as expansions in HSAT2 and HSAT3 satellite and contractions in ribosomal DNA repeats, were detected in POLQ - / - cells. In conjunction with the expanded telomere lengths of POLQ - /- cells, these results indicate a hitherto unrealized capacity of POLQ for regulation of repeat arrays within the genome. Our findings uncover novel considerations for the efficacy of POLQ inhibitors in clinical cancer interventions, where potential genome destabilizing consequences could drive clonal evolution and resistant disease.
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Affiliation(s)
- Kate Liddiard
- Division of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | - Alys N Aston-Evans
- Dementia Research Institute, School of Medicine, Cardiff University, Hadyn Ellis Building, Maindy Road, Cardiff CF24 4HQ, UK
| | - Kez Cleal
- Division of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | - Eric A Hendrickson
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, MN 55455, USA
| | - Duncan M Baird
- Division of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
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12
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Fanelli A, Marconato L, Licenziato L, Minoli L, Rouquet N, Aresu L. POT1 mutations are frequent and associated with Ki-67 index in canine diffuse large B-cell lymphoma. Front Vet Sci 2022; 9:968807. [PMID: 36016811 PMCID: PMC9396242 DOI: 10.3389/fvets.2022.968807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Accepted: 07/18/2022] [Indexed: 11/13/2022] Open
Abstract
Diffuse large B-cell lymphoma (DLBCL) represents one of the most frequent and deadliest neoplasia in dogs worldwide and is characterized by a remarkable degree of clinical heterogeneity, with poor chances to anticipate the outcome. Even if in the last years some recurrently mutated genes have been identified, the genetic origin of canine DLBCL (cDLBCL) is not yet completely understood. The aim of the present study was to assess the prevalence of POT1 mutations in cDLBCL and to elucidate the role of such gene in the pathogenesis of this tumor. Mutations in POT1 were retrieved in 34% of cases, in line with previous reports, but no significant associations with any clinico-pathological variable were identified. Likewise, POT1 mutations are not predictive of worse prognosis. Interestingly, Ki-67 index was significantly higher in dogs harboring POT1 mutations compared to wild-type ones. These results suggest that POT1 mutations may exert their pathogenic role in cDLBCL by promoting cellular proliferation.
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Affiliation(s)
- Antonella Fanelli
- Department of Veterinary Sciences, University of Turin, Turin, Italy
- *Correspondence: Antonella Fanelli
| | - Laura Marconato
- Department of Veterinary Medical Sciences, University of Bologna, Bologna, Italy
| | - Luca Licenziato
- Department of Veterinary Sciences, University of Turin, Turin, Italy
| | - Lucia Minoli
- Department of Veterinary Sciences, University of Turin, Turin, Italy
| | | | - Luca Aresu
- Department of Veterinary Sciences, University of Turin, Turin, Italy
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13
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Martínez P, Sánchez-Vázquez R, Ferrara-Romeo I, Serrano R, Flores JM, Blasco MA. A mouse model for Li-Fraumeni-Like Syndrome with cardiac angiosarcomas associated to POT1 mutations. PLoS Genet 2022; 18:e1010260. [PMID: 35727838 PMCID: PMC9212151 DOI: 10.1371/journal.pgen.1010260] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 05/16/2022] [Indexed: 11/18/2022] Open
Abstract
The shelterin protein POT1 has been found mutated in many different familial and sporadic cancers, however, no mouse models to understand the pathobiology of these mutations have been developed so far. To address the molecular mechanisms underlying the tumorigenic effects of POT1 mutant proteins in humans, we have generated a mouse model for the human POT1R117C mutation found in Li-Fraumeni-Like families with cases of cardiac angiosarcoma by introducing this mutation in the Pot1a endogenous locus, knock-in for Pot1aR117C. We find here that both mouse embryonic fibroblasts (MEFs) and tissues from Pot1a+/ki mice show longer telomeres than wild-type controls. Longer telomeres in Pot1a+/ki MEFs are dependent on telomerase activity as they are not found in double mutant Pot1a+/kiTert-/- telomerase-deficient MEFs. By using complementation assays we further show that POT1a pR117C exerts dominant-negative effects at telomeres. As in human Li-Fraumeni patients, heterozygous Pot1a+/ki mice spontaneously develop a high incidence of angiosarcomas, including cardiac angiosarcomas, and this is associated to the presence of abnormally long telomeres in endothelial cells as well as in the tumors. The Pot1a+/R117C mouse model constitutes a useful tool to understand human cancers initiated by POT1 mutations. We have generated a mouse model for the human POT1R117C mutation found in Li-Fraumeni-Like (LFL) families with cases of cardiac angiosarcoma by introducing this mutation in the Pot1a endogenous locus, knock-in for Pot1aR117C. The Pot1a+/ki mice show longer telomeres than wild-type controls. Longer telomeres in mutant mice are dependent on telomerase activity as they are not found in a telomerase deficient background. As in human Li-Fraumeni patients, heterozygous Pot1a+/ki mice spontaneously develop a high incidence of angiosarcomas, including cardiac angiosarcomas, and this is associated to the presence of abnormally long telomeres in endothelial cells as well as in the tumors. The ki-Pot1aR117C mouse constitutes a potential pre-clinical mouse model for LFL syndrome presenting with high angiosarcoma incidence that could provide in the future a very useful tool for the study of treatments for these tumors.
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Affiliation(s)
- Paula Martínez
- Telomeres and Telomerase Group, Molecular Oncology Program, Spanish National Cancer Centre (CNIO), Madrid, Spain
| | - Raúl Sánchez-Vázquez
- Telomeres and Telomerase Group, Molecular Oncology Program, Spanish National Cancer Centre (CNIO), Madrid, Spain
| | - Iole Ferrara-Romeo
- Telomeres and Telomerase Group, Molecular Oncology Program, Spanish National Cancer Centre (CNIO), Madrid, Spain
| | - Rosa Serrano
- Telomeres and Telomerase Group, Molecular Oncology Program, Spanish National Cancer Centre (CNIO), Madrid, Spain
| | - Juana M. Flores
- Animal Surgery and Medicine Department, Faculty of Veterinary Science, Complutense University of Madrid, Madrid, Spain
| | - Maria A. Blasco
- Telomeres and Telomerase Group, Molecular Oncology Program, Spanish National Cancer Centre (CNIO), Madrid, Spain
- * E-mail:
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14
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Zahid S, Aloe S, Sutherland JH, Holloman WK, Lue NF. Ustilago maydis telomere protein Pot1 harbors an extra N-terminal OB fold and regulates homology-directed DNA repair factors in a dichotomous and context-dependent manner. PLoS Genet 2022; 18:e1010182. [PMID: 35587917 PMCID: PMC9119445 DOI: 10.1371/journal.pgen.1010182] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 04/02/2022] [Indexed: 01/11/2023] Open
Abstract
The telomere G-strand binding protein Pot1 plays multifaceted roles in telomere maintenance and protection. We examined the structure and activities of Pot1 in Ustilago maydis, a fungal model that recapitulates key features of mammalian telomere regulation. Compared to the well-characterized primate and fission yeast Pot1 orthologs, UmPot1 harbors an extra N-terminal OB-fold domain (OB-N), which was recently shown to be present in most metazoans. UmPot1 binds directly to Rad51 and regulates the latter's strand exchange activity. Deleting the OB-N domain, which is implicated in Rad51-binding, caused telomere shortening, suggesting that Pot1-Rad51 interaction facilitates telomere maintenance. Depleting Pot1 through transcriptional repression triggered growth arrest as well as rampant recombination, leading to multiple telomere aberrations. In addition, telomere repeat RNAs transcribed from both the G- and C-strand were dramatically up-regulated, and this was accompanied by elevated levels of telomere RNA-DNA hybrids. Telomere abnormalities of pot1-deficient cells were suppressed, and cell viability was restored by the deletion of genes encoding Rad51 or Brh2 (the BRCA2 ortholog), indicating that homology-directed repair (HDR) proteins are key mediators of telomere aberrations and cellular toxicity. Together, these observations underscore the complex physical and functional interactions between Pot1 and DNA repair factors, leading to context-dependent and dichotomous effects of HDR proteins on telomere maintenance and protection.
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Affiliation(s)
- Syed Zahid
- Department of Microbiology & Immunology, W. R. Hearst Microbiology Research Center, Weill Cornell Medicine, New York, New York, United States of America
| | - Sarah Aloe
- Department of Microbiology & Immunology, W. R. Hearst Microbiology Research Center, Weill Cornell Medicine, New York, New York, United States of America
| | - Jeanette H. Sutherland
- Department of Microbiology & Immunology, W. R. Hearst Microbiology Research Center, Weill Cornell Medicine, New York, New York, United States of America
| | - William K. Holloman
- Department of Microbiology & Immunology, W. R. Hearst Microbiology Research Center, Weill Cornell Medicine, New York, New York, United States of America
| | - Neal F. Lue
- Department of Microbiology & Immunology, W. R. Hearst Microbiology Research Center, Weill Cornell Medicine, New York, New York, United States of America
- Sandra and Edward Meyer Cancer Center, Weill Cornell Medicine, New York, New York, United States of America
- * E-mail:
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15
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Enhanced radiosensitivity by 6-thio-dG via increasing telomere dysfunction and ataxia telangiectasia mutated inhibition in non-small cell lung cancer. RADIATION MEDICINE AND PROTECTION 2022. [DOI: 10.1016/j.radmp.2022.04.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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16
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Distinct functions of POT1 proteins contribute to the regulation of telomerase recruitment to telomeres. Nat Commun 2021; 12:5514. [PMID: 34535663 PMCID: PMC8448735 DOI: 10.1038/s41467-021-25799-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Accepted: 08/27/2021] [Indexed: 01/07/2023] Open
Abstract
Human shelterin components POT1 and TPP1 form a stable heterodimer that protects telomere ends from ATR-dependent DNA damage responses and regulates telomerase-dependent telomere extension. Mice possess two functionally distinct POT1 proteins. POT1a represses ATR/CHK1 DNA damage responses and the alternative non-homologous end-joining DNA repair pathway while POT1b regulates C-strand resection and recruits the CTC1-STN1-TEN1 (CST) complex to telomeres to mediate C-strand fill-in synthesis. Whether POT1a and POT1b are involved in regulating the length of the telomeric G-strand is unclear. Here we demonstrate that POT1b, independent of its CST function, enhances recruitment of telomerase to telomeres through three amino acids in its TPP1 interacting C-terminus. POT1b thus coordinates the synthesis of both telomeric G- and C-strands. In contrast, POT1a negatively regulates telomere length by inhibiting telomerase recruitment to telomeres. The identification of unique amino acids between POT1a and POT1b helps us understand mechanistically how human POT1 switches between end protective functions and promoting telomerase recruitment.
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17
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Goszczynski DE, Tinetti PS, Choi YH, Ross PJ, Hinrichs K. Allele-specific expression analysis reveals conserved and unique features of preimplantation development in equine ICSI embryos. Biol Reprod 2021; 105:1416-1426. [PMID: 34515759 DOI: 10.1093/biolre/ioab174] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 08/17/2021] [Accepted: 09/10/2021] [Indexed: 12/30/2022] Open
Abstract
Embryonic genome activation and dosage compensation are major genetic events in early development. Combined analysis of single embryo RNA-seq data and parental genome sequencing was used to evaluate parental contributions to early development and investigate X-chromosome dynamics. In addition, we evaluated dimorphism in gene expression between male and female embryos. Evaluation of parent-specific gene expression revealed a minor increase in paternal expression at the 4-cell stage that increased at the 8-cell stage. We also detected eight genes with allelic expression bias that may have an important role in early development, notably NANOGNB. The main actor in X-chromosome inactivation, XIST, was significantly upregulated at the 8-cell, morula, and blastocyst stages in female embryos, with high expression at the latter. Sexual dimorphism in gene expression was identified at all stages, with strong representation of the X-chromosome in females from the 16-cell to the blastocyst stage. Female embryos showed biparental X-chromosome expression at all stages after the 4-cell stage, demonstrating the absence of imprinted X-inactivation at the embryo level. The analysis of gene dosage showed incomplete dosage compensation (0.5 < X:A < 1) in MII oocytes and embryos up to the 4-cell stage, an increase of the X:A ratio at the 16-cell and morula stages after genome activation, and a decrease of the X:A ratio at the blastocyst stage, which might be associated with the beginning of X-chromosome inactivation. This study represents the first critical analysis of parent- and sex-specific gene expression in early equine embryos produced in vitro.
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Affiliation(s)
- D E Goszczynski
- Department of Animal Science, University of California, Davis, CA, USA
| | - P S Tinetti
- Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station, TX, USA
| | - Y H Choi
- Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station, TX, USA
| | - P J Ross
- Department of Animal Science, University of California, Davis, CA, USA
| | - K Hinrichs
- Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station, TX, USA
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18
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Garcia-Ruiz C, Conde de la Rosa L, Ribas V, Fernandez-Checa JC. MITOCHONDRIAL CHOLESTEROL AND CANCER. Semin Cancer Biol 2021; 73:76-85. [PMID: 32805396 PMCID: PMC7882000 DOI: 10.1016/j.semcancer.2020.07.014] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 07/22/2020] [Accepted: 07/29/2020] [Indexed: 12/11/2022]
Abstract
Cholesterol is a crucial component of membrane bilayers that determines their physical and functional properties. Cells largely satisfy their need for cholesterol through the novo synthesis from acetyl-CoA and this demand is particularly critical for cancer cells to sustain dysregulated cell proliferation. However, the association between serum or tissue cholesterol levels and cancer development is not well established as epidemiologic data do not consistently support this link. While most preclinical studies focused on the role of total celular cholesterol, the specific contribution of the mitochondrial cholesterol pool to alterations in cancer cell biology has been less explored. Although low compared to other bilayers, the mitochondrial cholesterol content plays an important physiological function in the synthesis of steroid hormones in steroidogenic tissues or bile acids in the liver and controls mitochondrial function. In addition, mitochondrial cholesterol metabolism generates oxysterols, which in turn, regulate multiple pathways, including cholesterol and lipid metabolism as well as cell proliferation. In the present review, we summarize the regulation of mitochondrial cholesterol, including its role in mitochondrial routine performance, cell death and chemotherapy resistance, highlighting its potential contribution to cancer. Of particular relevance is hepatocellular carcinoma, whose incidence in Western countries had tripled in the past decades due to the obesity and type II diabetes epidemic. A better understanding of the role of mitochondrial cholesterol in cancer development may open up novel opportunities for cancer therapy.
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Affiliation(s)
- Carmen Garcia-Ruiz
- Department of Cell Death and Proliferation, Institute of Biomedical Research of Barcelona (IIBB), CSIC, Barcelona, Spain; Liver Unit, Hospital Clinic I Provincial de Barcelona, Instituto de Investigaciones Biomédicas August Pi i Sunyer (IDIBAPS), Barcelona, Spain; Center for the Study of Liver and Gastrointestinal Diseases (CIBERehd), Carlos III National Institute of Health, Madrid, Spain; Center for ALPD, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
| | - Laura Conde de la Rosa
- Department of Cell Death and Proliferation, Institute of Biomedical Research of Barcelona (IIBB), CSIC, Barcelona, Spain; Liver Unit, Hospital Clinic I Provincial de Barcelona, Instituto de Investigaciones Biomédicas August Pi i Sunyer (IDIBAPS), Barcelona, Spain; Center for the Study of Liver and Gastrointestinal Diseases (CIBERehd), Carlos III National Institute of Health, Madrid, Spain
| | - Vicent Ribas
- Department of Cell Death and Proliferation, Institute of Biomedical Research of Barcelona (IIBB), CSIC, Barcelona, Spain; Liver Unit, Hospital Clinic I Provincial de Barcelona, Instituto de Investigaciones Biomédicas August Pi i Sunyer (IDIBAPS), Barcelona, Spain; Center for the Study of Liver and Gastrointestinal Diseases (CIBERehd), Carlos III National Institute of Health, Madrid, Spain
| | - Jose C Fernandez-Checa
- Department of Cell Death and Proliferation, Institute of Biomedical Research of Barcelona (IIBB), CSIC, Barcelona, Spain; Liver Unit, Hospital Clinic I Provincial de Barcelona, Instituto de Investigaciones Biomédicas August Pi i Sunyer (IDIBAPS), Barcelona, Spain; Center for the Study of Liver and Gastrointestinal Diseases (CIBERehd), Carlos III National Institute of Health, Madrid, Spain; Center for ALPD, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
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19
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Khodadadi E, Mir SM, Memar MY, Sadeghi H, Kashiri M, Faeghiniya M, Jamalpoor Z, Sheikh Arabi M. Shelterin complex at telomeres: Roles in cancers. GENE REPORTS 2021. [DOI: 10.1016/j.genrep.2021.101174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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20
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Chang X, Gurung RL, Wang L, Jin A, Li Z, Wang R, Beckman KB, Adams-Haduch J, Meah WY, Sim KS, Lim WK, Davila S, Tan P, Teo JX, Yeo KK, M Y, Liu S, Lim SC, Liu J, van Dam RM, Friedlander Y, Koh WP, Yuan JM, Khor CC, Heng CK, Dorajoo R. Low frequency variants associated with leukocyte telomere length in the Singapore Chinese population. Commun Biol 2021; 4:519. [PMID: 33941849 PMCID: PMC8093266 DOI: 10.1038/s42003-021-02056-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 03/26/2021] [Indexed: 02/02/2023] Open
Abstract
The role of low frequency variants associated with telomere length homeostasis in chronic diseases and mortalities is relatively understudied in the East-Asian population. Here we evaluated low frequency variants, including 1,915,154 Asian specific variants, for leukocyte telomere length (LTL) associations among 25,533 Singapore Chinese samples. Three East Asian specific variants in/near POT1, TERF1 and STN1 genes are associated with LTL (Meta-analysis P 2.49×10-14-6.94×10-10). Rs79314063, a missense variant (p.Asp410His) at POT1, shows effect 5.3 fold higher and independent of a previous common index SNP. TERF1 (rs79617270) and STN1 (rs139620151) are linked to LTL-associated common index SNPs at these loci. Rs79617270 is associated with cancer mortality [HR95%CI = 1.544 (1.173, 2.032), PAdj = 0.018] and 4.76% of the association between the rs79617270 and colon cancer is mediated through LTL. Overall, genetically determined LTL is particularly associated with lung adenocarcinoma [HR95%CI = 1.123 (1.051, 1.201), Padj = 0.007]. Ethnicity-specific low frequency variants may affect LTL homeostasis and associate with certain cancers.
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Affiliation(s)
- Xuling Chang
- Department of Paediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Khoo Teck Puat-National University Children's Medical Institute, National University Health System, Singapore, Singapore
| | - Resham L Gurung
- Clinical Research Unit, Khoo Teck Puat Hospital, Singapore, Singapore
| | - Ling Wang
- Genome Institute of Singapore, Agency for Science, Technology, and Research, Singapore, Singapore
| | - Aizhen Jin
- Health Services and Systems Research, Duke-NUS Medical School Singapore, Singapore, Singapore
| | - Zheng Li
- Genome Institute of Singapore, Agency for Science, Technology, and Research, Singapore, Singapore
| | - Renwei Wang
- Division of Cancer Control and Population Sciences, UPMC Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA, USA
| | - Kenneth B Beckman
- University of Minnesota Genomics Center, University of Minnesota, Minneapolis, MN, USA
| | - Jennifer Adams-Haduch
- Division of Cancer Control and Population Sciences, UPMC Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA, USA
| | - Wee Yang Meah
- Genome Institute of Singapore, Agency for Science, Technology, and Research, Singapore, Singapore
| | - Kar Seng Sim
- Genome Institute of Singapore, Agency for Science, Technology, and Research, Singapore, Singapore
| | - Weng Khong Lim
- SingHealth Duke-NUS Institute of Precision Medicine, Singapore, Singapore
- Cancer & Stem Cell Biology Program, Duke-NUS Medical School, Singapore, Singapore
- SingHealth Duke-NUS Genomic Medicine Centre, Singapore, Singapore
| | - Sonia Davila
- SingHealth Duke-NUS Institute of Precision Medicine, Singapore, Singapore
- Cardiovascular and Metabolic Disorders Program, Duke-NUS Medical School, Singapore, Singapore
| | - Patrick Tan
- Genome Institute of Singapore, Agency for Science, Technology, and Research, Singapore, Singapore
- SingHealth Duke-NUS Institute of Precision Medicine, Singapore, Singapore
- Cancer & Stem Cell Biology Program, Duke-NUS Medical School, Singapore, Singapore
- Cancer Science Institute of Singapore, National University of Singapore, Singapore, Singapore
| | - Jing Xian Teo
- SingHealth Duke-NUS Institute of Precision Medicine, Singapore, Singapore
| | - Khung Keong Yeo
- SingHealth Duke-NUS Institute of Precision Medicine, Singapore, Singapore
- Department of Cardiology, National Heart Centre Singapore, Singapore, Singapore
| | - Yiamunaa M
- Clinical Research Unit, Khoo Teck Puat Hospital, Singapore, Singapore
| | - Sylvia Liu
- Clinical Research Unit, Khoo Teck Puat Hospital, Singapore, Singapore
| | - Su Chi Lim
- Clinical Research Unit, Khoo Teck Puat Hospital, Singapore, Singapore
- Diabetes Centre, Admiralty Medical Centre, Singapore, Singapore
- Saw Swee Hock School of Public Health, National University of Singapore, Singapore, Singapore
| | - Jianjun Liu
- Genome Institute of Singapore, Agency for Science, Technology, and Research, Singapore, Singapore
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Rob M van Dam
- Saw Swee Hock School of Public Health, National University of Singapore, Singapore, Singapore
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Yechiel Friedlander
- School of Public Health and Community Medicine, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Woon-Puay Koh
- Health Services and Systems Research, Duke-NUS Medical School Singapore, Singapore, Singapore
- Saw Swee Hock School of Public Health, National University of Singapore, Singapore, Singapore
| | - Jian-Min Yuan
- Division of Cancer Control and Population Sciences, UPMC Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Chiea Chuen Khor
- Genome Institute of Singapore, Agency for Science, Technology, and Research, Singapore, Singapore
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore
| | - Chew-Kiat Heng
- Department of Paediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
- Khoo Teck Puat-National University Children's Medical Institute, National University Health System, Singapore, Singapore.
| | - Rajkumar Dorajoo
- Genome Institute of Singapore, Agency for Science, Technology, and Research, Singapore, Singapore.
- Health Services and Systems Research, Duke-NUS Medical School Singapore, Singapore, Singapore.
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21
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Kim WT, Hennick K, Johnson J, Finnerty B, Choo S, Short SB, Drubin C, Forster R, McMaster ML, Hockemeyer D. Cancer-associated POT1 mutations lead to telomere elongation without induction of a DNA damage response. EMBO J 2021; 40:e107346. [PMID: 33934394 PMCID: PMC8204863 DOI: 10.15252/embj.2020107346] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 03/09/2021] [Accepted: 03/16/2021] [Indexed: 12/28/2022] Open
Abstract
Mutations in the shelterin protein POT1 are associated with chronic lymphocytic leukemia (CLL), Hodgkin lymphoma, angiosarcoma, melanoma, and other cancers. These cancer‐associated POT1 (caPOT1) mutations are generally heterozygous, missense, or nonsense mutations occurring throughout the POT1 reading frame. Cancers with caPOT1 mutations have elongated telomeres and show increased genomic instability, but which of the two phenotypes promotes tumorigenesis is unclear. We tested the effects of CAS9‐engineered caPOT1 mutations in human embryonic and hematopoietic stem cells (hESCs and HSCs, respectively). HSCs with caPOT1 mutations did not show overt telomere damage. In vitro and in vivo competition experiments showed the caPOT1 mutations did not confer a selective disadvantage. Since DNA damage signaling is known to affect the fitness of HSCs, the data argue that caPOT1 mutations do not cause significant telomere damage. Furthermore, hESC lines with caPOT1 mutations showed no detectable telomere damage response while showing consistent telomere elongation. Thus, caPOT1 mutations are likely selected for during cancer progression because of their ability to elongate telomeres and extend the proliferative capacity of the incipient cancer cells.
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Affiliation(s)
- Won-Tae Kim
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Kelsey Hennick
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Joshua Johnson
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Brendan Finnerty
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Seunga Choo
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Sarah B Short
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Casey Drubin
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Ryan Forster
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Mary L McMaster
- Clinical Genetics Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, Bethesda, MD, USA
| | - Dirk Hockemeyer
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA.,Chan Zuckerberg Biohub, San Francisco, CA, USA.,Innovative Genomics Institute, University of California, Berkeley, Berkeley, CA, USA
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22
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Schmutz I, Mensenkamp AR, Takai KK, Haadsma M, Spruijt L, de Voer RM, Choo SS, Lorbeer FK, van Grinsven EJ, Hockemeyer D, Jongmans MCJ, de Lange T. TINF2 is a haploinsufficient tumor suppressor that limits telomere length. eLife 2020; 9:e61235. [PMID: 33258446 PMCID: PMC7707837 DOI: 10.7554/elife.61235] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 11/11/2020] [Indexed: 12/20/2022] Open
Abstract
Telomere shortening is a presumed tumor suppressor pathway that imposes a proliferative barrier (the Hayflick limit) during tumorigenesis. This model predicts that excessively long somatic telomeres predispose to cancer. Here, we describe cancer-prone families with two unique TINF2 mutations that truncate TIN2, a shelterin subunit that controls telomere length. Patient lymphocyte telomeres were unusually long. We show that the truncated TIN2 proteins do not localize to telomeres, suggesting that the mutations create loss-of-function alleles. Heterozygous knock-in of the mutations or deletion of one copy of TINF2 resulted in excessive telomere elongation in clonal lines, indicating that TINF2 is haploinsufficient for telomere length control. In contrast, telomere protection and genome stability were maintained in all heterozygous clones. The data establish that the TINF2 truncations predispose to a tumor syndrome. We conclude that TINF2 acts as a haploinsufficient tumor suppressor that limits telomere length to ensure a timely Hayflick limit.
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Affiliation(s)
- Isabelle Schmutz
- Laboratory for Cell Biology and Genetics, Rockefeller UniversityNew YorkUnited States
| | - Arjen R Mensenkamp
- Department of Human Genetics, Radboud University Medical CenterNijmegenNetherlands
| | - Kaori K Takai
- Laboratory for Cell Biology and Genetics, Rockefeller UniversityNew YorkUnited States
| | - Maaike Haadsma
- Department of Human Genetics, Radboud University Medical CenterNijmegenNetherlands
| | - Liesbeth Spruijt
- Department of Human Genetics, Radboud University Medical CenterNijmegenNetherlands
| | - Richarda M de Voer
- Department of Human Genetics, Radboud University Medical CenterNijmegenNetherlands
| | - Seunga Sara Choo
- Department of Molecular and Cellular Biology, University of California, BerkeleyBerkeleyUnited States
| | - Franziska K Lorbeer
- Department of Molecular and Cellular Biology, University of California, BerkeleyBerkeleyUnited States
| | - Emma J van Grinsven
- Department of Molecular and Cellular Biology, University of California, BerkeleyBerkeleyUnited States
| | - Dirk Hockemeyer
- Department of Molecular and Cellular Biology, University of California, BerkeleyBerkeleyUnited States
- Chan Zuckerberg BiohubSan FranciscoUnited States
| | | | - Titia de Lange
- Laboratory for Cell Biology and Genetics, Rockefeller UniversityNew YorkUnited States
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23
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Chartrand P, Sfeir A. A single-molecule view of telomerase regulation at telomeres. Mol Cell Oncol 2020; 7:1818537. [PMID: 33241110 DOI: 10.1080/23723556.2020.1818537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Telomerase plays a key role in the immortalization of cancer cells by maintaining telomeres length. Using single-molecule imaging of telomerase RNA molecules in cancer cells, we recently reported novel insights into the role of Cajal bodies in telomerase biogenesis and the regulation of telomerase recruitment to telomeres.
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Affiliation(s)
- Pascal Chartrand
- Department of Biochemistry and Molecular Medicine, Université De Montréal, Montréal, Qc, Canada
| | - Agnel Sfeir
- Skirball Institute of Biomolecular Medicine, NYU School of Medicine, New York, NY, USA
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24
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Cicconi A, Rai R, Xiong X, Broton C, Al-Hiyasat A, Hu C, Dong S, Sun W, Garbarino J, Bindra RS, Schildkraut C, Chen Y, Chang S. Microcephalin 1/BRIT1-TRF2 interaction promotes telomere replication and repair, linking telomere dysfunction to primary microcephaly. Nat Commun 2020; 11:5861. [PMID: 33203878 PMCID: PMC7672075 DOI: 10.1038/s41467-020-19674-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 10/22/2020] [Indexed: 01/07/2023] Open
Abstract
Telomeres protect chromosome ends from inappropriately activating the DNA damage and repair responses. Primary microcephaly is a key clinical feature of several human telomere disorder syndromes, but how microcephaly is linked to dysfunctional telomeres is not known. Here, we show that the microcephalin 1/BRCT-repeats inhibitor of hTERT (MCPH1/BRIT1) protein, mutated in primary microcephaly, specifically interacts with the TRFH domain of the telomere binding protein TRF2. The crystal structure of the MCPH1-TRF2 complex reveals that this interaction is mediated by the MCPH1 330YRLSP334 motif. TRF2-dependent recruitment of MCPH1 promotes localization of DNA damage factors and homology directed repair of dysfunctional telomeres lacking POT1-TPP1. Additionally, MCPH1 is involved in the replication stress response, promoting telomere replication fork progression and restart of stalled telomere replication forks. Our work uncovers a previously unrecognized role for MCPH1 in promoting telomere replication, providing evidence that telomere replication defects may contribute to the onset of microcephaly.
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Affiliation(s)
- Alessandro Cicconi
- grid.47100.320000000419368710Department of Laboratory Medicine, Yale University School of Medicine, 330 Cedar St., New Haven, CT 06520 USA
| | - Rekha Rai
- grid.47100.320000000419368710Department of Laboratory Medicine, Yale University School of Medicine, 330 Cedar St., New Haven, CT 06520 USA
| | - Xuexue Xiong
- grid.507739.fState Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, 200031 China
| | - Cayla Broton
- grid.47100.320000000419368710Department of Laboratory Medicine, Yale University School of Medicine, 330 Cedar St., New Haven, CT 06520 USA ,grid.5386.8000000041936877XTri- Institutional MD/PhD Program, Weill Cornell Medical College, New York, NY 10065 USA
| | - Amer Al-Hiyasat
- grid.47100.320000000419368710Department of Laboratory Medicine, Yale University School of Medicine, 330 Cedar St., New Haven, CT 06520 USA ,grid.47100.320000000419368710Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, 330 Cedar St., New Haven, CT 06520 USA
| | - Chunyi Hu
- grid.507739.fState Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, 200031 China
| | - Siying Dong
- grid.507739.fState Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, 200031 China
| | - Wenqi Sun
- grid.507739.fState Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, 200031 China
| | - Jennifer Garbarino
- grid.47100.320000000419368710Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, 330 Cedar St., New Haven, CT 06520 USA ,grid.47100.320000000419368710Department of Therapeutic Radiology, Yale University School of Medicine, 330 Cedar St., New Haven, CT 06520 USA
| | - Ranjit S. Bindra
- grid.47100.320000000419368710Department of Therapeutic Radiology, Yale University School of Medicine, 330 Cedar St., New Haven, CT 06520 USA ,grid.47100.320000000419368710Department of Experimental Pathology, Yale University School of Medicine, 330 Cedar St., New Haven, CT 06520 USA
| | - Carl Schildkraut
- grid.251993.50000000121791997Department of Cell Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461 USA
| | - Yong Chen
- grid.507739.fState Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, 200031 China
| | - Sandy Chang
- grid.47100.320000000419368710Department of Laboratory Medicine, Yale University School of Medicine, 330 Cedar St., New Haven, CT 06520 USA ,grid.47100.320000000419368710Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, 330 Cedar St., New Haven, CT 06520 USA ,grid.47100.320000000419368710Department of Pathology, Yale University School of Medicine, 330 Cedar St., New Haven, CT 06520 USA
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Wu Y, Poulos RC, Reddel RR. Role of POT1 in Human Cancer. Cancers (Basel) 2020; 12:cancers12102739. [PMID: 32987645 PMCID: PMC7598640 DOI: 10.3390/cancers12102739] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2020] [Revised: 09/20/2020] [Accepted: 09/22/2020] [Indexed: 12/11/2022] Open
Abstract
Simple Summary The segmentation of eukaryotic genomes into discrete linear chromosomes requires processes to solve several major biological problems, including prevention of the chromosome ends being recognized as DNA breaks and compensation for the shortening that occurs when linear DNA is replicated. A specialized set of six proteins, collectively referred to as shelterin, is involved in both of these processes, and mutations in several of these are now known to be involved in cancer. Here, we focus on Protection of Telomeres 1 (POT1), the shelterin protein that appears to be most commonly involved in cancer, and consider the clinical significance of findings about its biological functions and the prevalence of inherited and acquired mutations in the POT1 gene. Abstract Telomere abnormalities facilitate cancer development by contributing to genomic instability and cellular immortalization. The Protection of Telomeres 1 (POT1) protein is an essential subunit of the shelterin telomere binding complex. It directly binds to single-stranded telomeric DNA, protecting chromosomal ends from an inappropriate DNA damage response, and plays a role in telomere length regulation. Alterations of POT1 have been detected in a range of cancers. Here, we review the biological functions of POT1, the prevalence of POT1 germline and somatic mutations across cancer predisposition syndromes and tumor types, and the dysregulation of POT1 expression in cancers. We propose a framework for understanding how POT1 abnormalities may contribute to oncogenesis in different cell types. Finally, we summarize the clinical implications of POT1 alterations in the germline and in cancer, and possible approaches for the development of targeted cancer therapies.
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Affiliation(s)
- Yangxiu Wu
- Cancer Research Unit, Children’s Medical Research Institute, Faculty of Medicine and Health, The University of Sydney, Westmead NSW 2145, Australia;
- ProCan® Cancer Data Science Group, Children’s Medical Research Institute, Faculty of Medicine and Health, The University of Sydney, Westmead NSW 2145, Australia;
| | - Rebecca C. Poulos
- ProCan® Cancer Data Science Group, Children’s Medical Research Institute, Faculty of Medicine and Health, The University of Sydney, Westmead NSW 2145, Australia;
| | - Roger R. Reddel
- Cancer Research Unit, Children’s Medical Research Institute, Faculty of Medicine and Health, The University of Sydney, Westmead NSW 2145, Australia;
- Correspondence: ; Tel.: +61-2-8865-2901
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MiR-185 targets POT1 to induce telomere dysfunction and cellular senescence. Aging (Albany NY) 2020; 12:14791-14807. [PMID: 32687062 PMCID: PMC7425516 DOI: 10.18632/aging.103541] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Accepted: 06/01/2020] [Indexed: 12/20/2022]
Abstract
Protection of telomere 1 (POT1), the telomeric single-stranded DNA (ssDNA)-binding protein in the shelterin complex, has been implicated in the DNA damage response, tumorigenesis and aging. Telomere dysfunction induced by telomere deprotection could accelerate cellular senescence in primary human cells. While previous work demonstrated the biological mechanism of POT1 in aging and cancer, how POT1 is posttranscriptionally regulated remains largely unknown. To better understand the POT1 regulatory axis, we performed bioinformatic prediction, and selected candidates were further confirmed by dual-luciferase reporter assay. Collectively, our results revealed that miR-185 can significantly reduce POT1 mRNA and protein levels by directly targeting the POT1 3’-untranslated region (3’-UTR). Overexpression of miR-185 increased telomere dysfunction-induced foci (TIF) signals in both cancer cells and primary human fibroblasts. Elevated miR-185 led to telomere elongation in the telomerase-positive cell line HTC75, which was phenotypically consistent with POT1 knocking down. Moreover, miR-185 accelerated the replicative senescence process in primary human fibroblasts in a POT1-dependent manner. Interestingly, increased serum miR-185 could represent a potential aging-related biomarker. Taken together, our findings reveal miR-185 as a novel aging-related miRNA that targets POT1 and provide insight into the telomere and senescence regulatory network at both the intracellular and extracellular levels.
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27
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Single-Molecule Imaging of Telomerase RNA Reveals a Recruitment-Retention Model for Telomere Elongation. Mol Cell 2020; 79:115-126.e6. [DOI: 10.1016/j.molcel.2020.05.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 04/13/2020] [Accepted: 05/03/2020] [Indexed: 11/23/2022]
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Srivastava A, Miao B, Skopelitou D, Kumar V, Kumar A, Paramasivam N, Bonora E, Hemminki K, Försti A, Bandapalli OR. A Germline Mutation in the POT1 Gene Is a Candidate for Familial Non-Medullary Thyroid Cancer. Cancers (Basel) 2020; 12:cancers12061441. [PMID: 32492864 PMCID: PMC7352431 DOI: 10.3390/cancers12061441] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 05/27/2020] [Accepted: 05/28/2020] [Indexed: 02/06/2023] Open
Abstract
Non-medullary thyroid cancer (NMTC) is a common endocrine malignancy with a genetic basis that has yet to be unequivocally established. In a recent whole-genome sequencing study of five families with occurrence of NMTCs, we shortlisted promising variants with the help of bioinformatics tools. Here, we report in silico analyses and in vitro experiments on a novel germline variant (p.V29L) in the highly conserved oligonucleotide/oligosaccharide binding domain of the Protection of Telomeres 1 (POT1) gene in one of the families. The results showed a reduction in telomere-bound POT1 levels in the mutant protein as compared to its wild-type counterpart. HEK293T cells carrying POT1 p.V29L showed increased telomere length in comparison to wild-type cells, suggesting that the mutation causes telomere dysfunction and may play a role in predisposition to NMTC in this family. While one germline mutation in POT1 has already been reported in a melanoma-prone family with prevalence of thyroid cancers, we report the first of such mutations in a family affected solely by NMTCs, thus expanding current knowledge on shelterin complex-associated cancers.
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Affiliation(s)
- Aayushi Srivastava
- Division of Molecular Genetic Epidemiology, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany; (A.S.); (D.S.); (A.K.); (K.H.); (A.F.)
- Hopp Children’s Cancer Center (KiTZ), 69120 Heidelberg, Germany;
- Division of Pediatric Neurooncology, German Cancer Research Center (DKFZ), German Cancer Consortium (DKTK), 69120 Heidelberg, Germany
- Medical Faculty, Heidelberg University, 69120 Heidelberg, Germany
| | - Beiping Miao
- Hopp Children’s Cancer Center (KiTZ), 69120 Heidelberg, Germany;
- Division of Pediatric Neurooncology, German Cancer Research Center (DKFZ), German Cancer Consortium (DKTK), 69120 Heidelberg, Germany
| | - Diamanto Skopelitou
- Division of Molecular Genetic Epidemiology, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany; (A.S.); (D.S.); (A.K.); (K.H.); (A.F.)
- Hopp Children’s Cancer Center (KiTZ), 69120 Heidelberg, Germany;
- Division of Pediatric Neurooncology, German Cancer Research Center (DKFZ), German Cancer Consortium (DKTK), 69120 Heidelberg, Germany
- Medical Faculty, Heidelberg University, 69120 Heidelberg, Germany
| | - Varun Kumar
- Department of Medicine I and Clinical Chemistry, University Hospital of Heidelberg, 69120 Heidelberg, Germany;
| | - Abhishek Kumar
- Division of Molecular Genetic Epidemiology, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany; (A.S.); (D.S.); (A.K.); (K.H.); (A.F.)
- Institute of Bioinformatics, International Technology Park, Bangalore 560066, India
- Manipal Academy of Higher Education (MAHE), Manipal 576104, Karnataka, India
| | - Nagarajan Paramasivam
- Computational Oncology, Molecular Diagnostics Program, National Center for Tumor Diseases (NCT), 69120 Heidelberg, Germany;
| | - Elena Bonora
- Unit of Medical Genetics, Department of Medical and Surgical Sciences, S.Orsola-Malpighi Hospital, University of Bologna, 40138 Bologna, Italy;
| | - Kari Hemminki
- Division of Molecular Genetic Epidemiology, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany; (A.S.); (D.S.); (A.K.); (K.H.); (A.F.)
- Faculty of Medicine and Biomedical Center in Pilsen, Charles University in Prague, 30605 Pilsen, Czech Republic
| | - Asta Försti
- Division of Molecular Genetic Epidemiology, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany; (A.S.); (D.S.); (A.K.); (K.H.); (A.F.)
- Hopp Children’s Cancer Center (KiTZ), 69120 Heidelberg, Germany;
- Division of Pediatric Neurooncology, German Cancer Research Center (DKFZ), German Cancer Consortium (DKTK), 69120 Heidelberg, Germany
| | - Obul Reddy Bandapalli
- Division of Molecular Genetic Epidemiology, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany; (A.S.); (D.S.); (A.K.); (K.H.); (A.F.)
- Hopp Children’s Cancer Center (KiTZ), 69120 Heidelberg, Germany;
- Division of Pediatric Neurooncology, German Cancer Research Center (DKFZ), German Cancer Consortium (DKTK), 69120 Heidelberg, Germany
- Medical Faculty, Heidelberg University, 69120 Heidelberg, Germany
- Correspondence:
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Frequent Mutations of POT1 Distinguish Pulmonary Sarcomatoid Carcinoma From Other Lung Cancer Histologies. Clin Lung Cancer 2020; 21:e523-e527. [PMID: 32414627 DOI: 10.1016/j.cllc.2020.04.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 03/16/2020] [Accepted: 04/03/2020] [Indexed: 12/28/2022]
Abstract
INTRODUCTION Pulmonary sarcomatoid carcinoma (PSC) is a rare subtype of non-small-cell lung cancer (NSCLC) harboring mutations in many canonical NSCLC-driver genes (eg, TP53, KRAS, MET). Protection of telomeres 1 (POT1) mutations are observed in angiosarcoma and chronic lymphocytic leukemia, but their frequency in other solid tumors, including NSCLC subtypes, has not been rigorously explored. MATERIALS AND METHODS We analyzed next-generation sequencing data from 62,368 tumors, including 11,134 NSCLCs and 100 PSCs. We performed logistic regression to identify associations between POT1 mutation frequency and tumor histology across 184 tumor categories, adjusting for tumor mutational burden. We further explored co-occurring gene mutations in genes previously reported to underlie PSC tumorigenesis. RESULTS Across 184 tumor categories, POT1 mutations were most frequent in PSC and were 14 times more common in PSC (28%) than in other tumor types (P = 1.23 × 10-31) and 6.7 times more common in PSC than other NSCLCs (P = 5.1 × 10-17). PSCs harboring KRAS mutations were significantly more likely to harbor POT1 mutations (P = 1.3 × 10-3), whereas those with TP53 mutations were less likely to harbor POT1 mutations (P = .037). One-fourth of POT1-mutated PSCs harbored a second POT1 mutation. Across all PSCs, 83% of POT1 mutations were in the OB1/OB2 (DNA-binding) domain (P = 1.5 × 10-5), an enrichment not observed in other tumor types. CONCLUSION We report an unanticipated association between POT1 mutation and PSC. Unlike other molecular alterations that are frequent across NSCLC subtypes, POT1 mutations are largely unique to PSC. This finding may help to develop disease-defining molecular subgroups within PSC and presents opportunities for molecularly stratified prognostication and therapy.
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Berei J, Eckburg A, Miliavski E, Anderson AD, Miller RJ, Dein J, Giuffre AM, Tang D, Deb S, Racherla KS, Patel M, Vela MS, Puri N. Potential Telomere-Related Pharmacological Targets. Curr Top Med Chem 2020; 20:458-484. [DOI: 10.2174/1568026620666200109114339] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 11/21/2019] [Accepted: 11/21/2019] [Indexed: 12/22/2022]
Abstract
Telomeres function as protective caps at the terminal portion of chromosomes, containing
non-coding nucleotide sequence repeats. As part of their protective function, telomeres preserve genomic
integrity and minimize chromosomal exposure, thus limiting DNA damage responses. With
continued mitotic divisions in normal cells, telomeres progressively shorten until they reach a threshold
at a point where they activate senescence or cell death pathways. However, the presence of the enzyme
telomerase can provide functional immortality to the cells that have reached or progressed past
senescence. In senescent cells that amass several oncogenic mutations, cancer formation can occur due
to genomic instability and the induction of telomerase activity. Telomerase has been found to be expressed
in over 85% of human tumors and is labeled as a near-universal marker for cancer. Due to this
feature being present in a majority of tumors but absent in most somatic cells, telomerase and telomeres
have become promising targets for the development of new and effective anticancer therapeutics.
In this review, we evaluate novel anticancer targets in development which aim to alter telomerase
or telomere function. Additionally, we analyze the progress that has been made, including preclinical
studies and clinical trials, with therapeutics directed at telomere-related targets. Furthermore, we review
the potential telomere-related therapeutics that are used in combination therapy with more traditional
cancer treatments. Throughout the review, topics related to medicinal chemistry are discussed,
including drug bioavailability and delivery, chemical structure-activity relationships of select therapies,
and the development of a unique telomere assay to analyze compounds affecting telomere elongation.
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Affiliation(s)
- Joseph Berei
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, United States
| | - Adam Eckburg
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, United States
| | - Edward Miliavski
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, United States
| | - Austin D. Anderson
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, United States
| | - Rachel J. Miller
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, United States
| | - Joshua Dein
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, United States
| | - Allison M. Giuffre
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, United States
| | - Diana Tang
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, United States
| | - Shreya Deb
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, United States
| | - Kavya Sri Racherla
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, United States
| | - Meet Patel
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, United States
| | - Monica Saravana Vela
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, United States
| | - Neelu Puri
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, United States
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Cicconi A, Chang S. Shelterin and the replisome: at the intersection of telomere repair and replication. Curr Opin Genet Dev 2020; 60:77-84. [PMID: 32171974 DOI: 10.1016/j.gde.2020.02.016] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Revised: 02/10/2020] [Accepted: 02/12/2020] [Indexed: 12/30/2022]
Abstract
Telomeres are G-rich repetitive sequences that are difficult to replicate, resulting in increased replication stress that can threaten genome stability. Shelterin protects telomeres from engaging in aberrant DNA repair and dictates the choice of DNA repair pathway at dysfunctional telomeres. Recently, shelterin has been shown to participate in telomere replication. Here we review the most recent discoveries documenting the mechanisms by which shelterin represses DNA repair pathways at telomeres while assisting its replication. The interplay between shelterin and the replisome complex highlights a novel connection between telomere maintenance and repair.
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Affiliation(s)
- Alessandro Cicconi
- Department of Laboratory Medicine, Yale University School of Medicine, 330 Cedar St., New Haven, CT 06520, USA
| | - Sandy Chang
- Department of Laboratory Medicine, Yale University School of Medicine, 330 Cedar St., New Haven, CT 06520, USA; Department of Pathology, Yale University School of Medicine, 330 Cedar St., New Haven, CT 06520, USA; Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, 330 Cedar St., New Haven, CT 06520, USA.
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32
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Gong Y, Stock AJ, Liu Y. The enigma of excessively long telomeres in cancer: lessons learned from rare human POT1 variants. Curr Opin Genet Dev 2020; 60:48-55. [PMID: 32155570 DOI: 10.1016/j.gde.2020.02.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 01/17/2020] [Accepted: 02/02/2020] [Indexed: 01/10/2023]
Abstract
The discovery that rare POT1 variants are associated with extremely long telomeres and increased cancer predisposition has provided a framework to revisit the relationship between telomere length and cancer development. Telomere shortening is linked with increased risk for cancer. However, over the past decade, there is increasing evidence to show that extremely long telomeres caused by mutations in shelterin components (POT1, TPP1, and RAP1) also display an increased risk of cancer. Here, we will review current knowledge on germline mutations of POT1 identified from cancer-prone families. In particular, we will discuss some common features presented by the mutations through structure-function studies. We will further provide an overview of how POT1 mutations affect telomere length regulation and tumorigenesis.
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Affiliation(s)
- Yi Gong
- Biomedical Research Center, National Institute on Aging/National Institutes of Health, 251 Bayview Blvd, Baltimore, MD, USA.
| | - Amanda J Stock
- Biomedical Research Center, National Institute on Aging/National Institutes of Health, 251 Bayview Blvd, Baltimore, MD, USA
| | - Yie Liu
- Biomedical Research Center, National Institute on Aging/National Institutes of Health, 251 Bayview Blvd, Baltimore, MD, USA.
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Shen E, Xiu J, Lopez GY, Bentley R, Jalali A, Heimberger AB, Bainbridge MN, Bondy ML, Walsh KM. POT1 mutation spectrum in tumour types commonly diagnosed among POT1-associated hereditary cancer syndrome families. J Med Genet 2020; 57:664-670. [PMID: 31937561 DOI: 10.1136/jmedgenet-2019-106657] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 12/20/2019] [Accepted: 12/21/2019] [Indexed: 12/17/2022]
Abstract
BACKGROUND The shelterin complex is composed of six proteins that protect and regulate telomere length, including protection of telomeres 1 (POT1). Germline POT1 mutations are associated with an autosomal dominant familial cancer syndrome presenting with diverse malignancies, including glioma, angiosarcoma, colorectal cancer and melanoma. Although somatic POT1 mutations promote telomere elongation and genome instability in chronic lymphocytic leukaemia, the contribution of POT1 mutations to development of other sporadic cancers is largely unexplored. METHODS We performed logistic regression, adjusted for tumour mutational burden, to identify associations between POT1 mutation frequency and tumour type in 62 368 tumours undergoing next-generation sequencing. RESULTS A total of 1834 tumours harboured a non-benign mutation of POT1 (2.94%), of which 128 harboured a mutation previously reported to confer familial cancer risk in the setting of germline POT1 deficiency. Angiosarcoma was 11 times more likely than other tumours to harbour a POT1 mutation (p=1.4×10-20), and 65% of POT1-mutated angiosarcoma had >1 mutations in POT1. Malignant gliomas were 1.7 times less likely to harbour a POT1 mutation (p=1.2×10-3) than other tumour types. Colorectal cancer was 1.2 times less likely to harbour a POT1 mutation (p=0.012), while melanoma showed no differences in POT1 mutation frequency versus other tumours (p=0.67). CONCLUSIONS These results confirm a role for shelterin dysfunction in angiosarcoma development but suggest that gliomas arising in the context of germline POT1 deficiency activate a telomere-lengthening mechanism that is uncommon in gliomagenesis.
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Affiliation(s)
- Erica Shen
- Department of Neurosurgery, Duke University School of Medicine, Durham, North Carolina, USA
| | - Joanne Xiu
- Medical Affairs, Caris Life Sciences Inc, Phoenix, Arizona, USA
| | - Giselle Y Lopez
- Department of Pathology, Duke University School of Medicine, Durham, North Carolina, USA.,Duke Cancer Institute, Duke University School of Medicine, Durham, North Carolina, USA
| | - Rex Bentley
- Department of Pathology, Duke University School of Medicine, Durham, North Carolina, USA.,Duke Cancer Institute, Duke University School of Medicine, Durham, North Carolina, USA
| | - Ali Jalali
- Department of Neurosurgery, Baylor College of Medicine, Houston, Texas, USA
| | - Amy B Heimberger
- Department of Neurosurgery, University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | | | - Melissa L Bondy
- Epidemiology and Population Health, Stanford University School of Medicine, Palo Alto, California, USA
| | - Kyle M Walsh
- Department of Neurosurgery, Duke University School of Medicine, Durham, North Carolina, USA .,Department of Pathology, Duke University School of Medicine, Durham, North Carolina, USA.,Duke Cancer Institute, Duke University School of Medicine, Durham, North Carolina, USA
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Smith EM, Pendlebury DF, Nandakumar J. Structural biology of telomeres and telomerase. Cell Mol Life Sci 2020; 77:61-79. [PMID: 31728577 PMCID: PMC6986361 DOI: 10.1007/s00018-019-03369-x] [Citation(s) in RCA: 108] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 10/11/2019] [Accepted: 10/31/2019] [Indexed: 01/16/2023]
Abstract
Telomeres are protein-DNA complexes that protect chromosome ends from illicit ligation and resection. Telomerase is a ribonucleoprotein enzyme that synthesizes telomeric DNA to counter telomere shortening. Human telomeres are composed of complexes between telomeric DNA and a six-protein complex known as shelterin. The shelterin proteins TRF1 and TRF2 provide the binding affinity and specificity for double-stranded telomeric DNA, while the POT1-TPP1 shelterin subcomplex coats the single-stranded telomeric G-rich overhang that is characteristic of all our chromosome ends. By capping chromosome ends, shelterin protects telomeric DNA from unwanted degradation and end-to-end fusion events. Structures of the human shelterin proteins reveal a network of constitutive and context-specific interactions. The shelterin protein-DNA structures reveal the basis for both the high affinity and DNA sequence specificity of these interactions, and explain how shelterin efficiently protects chromosome ends from genome instability. Several protein-protein interactions, many provided by the shelterin component TIN2, are critical for upholding the end-protection function of shelterin. A survey of these protein-protein interfaces within shelterin reveals a series of "domain-peptide" interactions that allow for efficient binding and adaptability towards new functions. While the modular nature of shelterin has facilitated its part-by-part structural characterization, the interdependence of subunits within telomerase has made its structural solution more challenging. However, the exploitation of several homologs in combination with recent advancements in cryo-EM capabilities has led to an exponential increase in our knowledge of the structural biology underlying telomerase function. Telomerase homologs from a wide range of eukaryotes show a typical retroviral reverse transcriptase-like protein core reinforced with elements that deliver telomerase-specific functions including recruitment to telomeres and high telomere-repeat addition processivity. In addition to providing the template for reverse transcription, the RNA component of telomerase provides a scaffold for the catalytic and accessory protein subunits, defines the limits of the telomeric repeat sequence, and plays a critical role in RNP assembly, stability, and trafficking. While a high-resolution definition of the human telomerase structure is only beginning to emerge, the quick pace of technical progress forecasts imminent breakthroughs in this area. Here, we review the structural biology surrounding telomeres and telomerase to provide a molecular description of mammalian chromosome end protection and end replication.
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Affiliation(s)
- Eric M Smith
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, 48109, USA
- Program in Chemical Biology, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Devon F Pendlebury
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, 48109, USA
- Program in Chemical Biology, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Jayakrishnan Nandakumar
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, 48109, USA.
- Program in Chemical Biology, University of Michigan, Ann Arbor, MI, 48109, USA.
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Rai R, Gu P, Broton C, Kumar-Sinha C, Chen Y, Chang S. The Replisome Mediates A-NHEJ Repair of Telomeres Lacking POT1-TPP1 Independently of MRN Function. Cell Rep 2019; 29:3708-3725.e5. [PMID: 31825846 PMCID: PMC7001145 DOI: 10.1016/j.celrep.2019.11.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 09/22/2019] [Accepted: 11/04/2019] [Indexed: 02/07/2023] Open
Abstract
Telomeres use shelterin to protect chromosome ends from activating the DNA damage sensor MRE11-RAD50-NBS1 (MRN), repressing ataxia-telangiectasia, mutated (ATM) and ATM and Rad3-related (ATR) dependent DNA damage checkpoint responses. The MRE11 nuclease is thought to be essential for the resection of the 5' C-strand to generate the microhomologies necessary for alternative non-homologous end joining (A-NHEJ) repair. In the present study, we uncover DNA damage signaling and repair pathways engaged by components of the replisome complex to repair dysfunctional telomeres. In cells lacking MRN, single-stranded telomeric overhangs devoid of POT1-TPP1 do not recruit replication protein A (RPA), ATR-interacting protein (ATRIP), and RAD 51. Rather, components of the replisome complex, including Claspin, Proliferating cell nuclear antigen (PCNA), and Downstream neighbor of SON (DONSON), initiate DNA-PKcs-mediated p-CHK1 activation and A-NHEJ repair. In addition, Claspin directly interacts with TRF2 and recruits EXO1 to newly replicated telomeres to promote 5' end resection. Our data indicate that MRN is dispensable for the repair of dysfunctional telomeres lacking POT1-TPP1 and highlight the contributions of the replisome in telomere repair.
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Affiliation(s)
- Rekha Rai
- Departments of Laboratory Medicine, Yale University School of Medicine, 330 Cedar St., New Haven, CT 06520, USA.
| | - Peili Gu
- Departments of Laboratory Medicine, Yale University School of Medicine, 330 Cedar St., New Haven, CT 06520, USA
| | - Cayla Broton
- Departments of Laboratory Medicine, Yale University School of Medicine, 330 Cedar St., New Haven, CT 06520, USA; Tri-Institutional MD/PhD Program, Weill Cornell Medical College, New York, NY 10065, USA
| | - Chandan Kumar-Sinha
- Department of Pathology, University of Michigan School of Medicine, Ann Arbor, MI 48109, USA
| | - Yong Chen
- National Center for Protein Science Shanghai, Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, 333 Haike Road, Shanghai 201210, China
| | - Sandy Chang
- Departments of Laboratory Medicine, Yale University School of Medicine, 330 Cedar St., New Haven, CT 06520, USA; Department of Pathology, Yale University School of Medicine, 330 Cedar St., New Haven, CT 06520, USA; Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, 330 Cedar St., New Haven, CT 06520, USA.
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Investigating architecture and structure-function relationships in cold shock DNA-binding domain family using structural genomics-based approach. Int J Biol Macromol 2019; 133:484-494. [DOI: 10.1016/j.ijbiomac.2019.04.135] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 04/09/2019] [Accepted: 04/17/2019] [Indexed: 11/19/2022]
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McMaster ML, Sun C, Landi MT, Savage SA, Rotunno M, Yang XR, Jones K, Vogt A, Hutchinson A, Zhu B, Wang M, Hicks B, Thirunavukarason A, Stewart DR, Koutros S, Goldstein AM, Chanock SJ, Caporaso NE, Tucker MA, Goldin LR, Liu Y. Germline mutations in Protection of Telomeres 1 in two families with Hodgkin lymphoma. Br J Haematol 2019; 181:372-377. [PMID: 29693246 DOI: 10.1111/bjh.15203] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 01/31/2018] [Accepted: 02/01/2018] [Indexed: 01/29/2023]
Abstract
In a previous whole exome sequencing of patients from 41 families with Hodgkin lymphoma, we identified two families with distinct heterozygous rare coding variants in POT1 (D224N and Y36H), both in a highly conserved region of the gene. POT1 D224N mutant did not bind to a single-stranded telomere oligonucleotide in vitro suggesting the mutation perturbs POT1's ability to bind to the telomeric G-rich overhang. Human HT1080 cells expressing POT1 D224N and lymphoblastoid cells carrying Y36H both showed increased telomere length and fragility in comparison to wild type cells. This strongly suggests that mutant POT1 causes chromosome instability and may play a role in lymphomagenesis in these families.
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Affiliation(s)
- Mary L McMaster
- Clinical Genetics Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute; NIH, Bethesda, MD, USA
| | - Chongkui Sun
- Laboratory of Molecular Gerontology, National Institute on Aging/National Institute of Health, Baltimore, MD, USA
| | - Maria T Landi
- Integrative Tumor Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute; NIH, Bethesda, MD, USA
| | - Sharon A Savage
- Clinical Genetics Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute; NIH, Bethesda, MD, USA
| | - Melissa Rotunno
- Epidemiology and Genomics Research Program, Division of Cancer Control and Population Sciences, National Cancer Institute, NIH, Bethesda, MD, USA
| | - Xiaohong R Yang
- Integrative Tumor Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute; NIH, Bethesda, MD, USA
| | - Kristine Jones
- Cancer Genomics Research Laboratory, Division of Cancer Epidemiology and Genetics, National Cancer Institute; NIH, Bethesda, MD, USA
| | - Aurélie Vogt
- Cancer Genomics Research Laboratory, Division of Cancer Epidemiology and Genetics, National Cancer Institute; NIH, Bethesda, MD, USA
| | - Amy Hutchinson
- Cancer Genomics Research Laboratory, Division of Cancer Epidemiology and Genetics, National Cancer Institute; NIH, Bethesda, MD, USA
| | - Bin Zhu
- Cancer Genomics Research Laboratory, Division of Cancer Epidemiology and Genetics, National Cancer Institute; NIH, Bethesda, MD, USA
| | - Mingyi Wang
- Cancer Genomics Research Laboratory, Division of Cancer Epidemiology and Genetics, National Cancer Institute; NIH, Bethesda, MD, USA
| | - Belynda Hicks
- Cancer Genomics Research Laboratory, Division of Cancer Epidemiology and Genetics, National Cancer Institute; NIH, Bethesda, MD, USA
| | - Anand Thirunavukarason
- Laboratory of Molecular Gerontology, National Institute on Aging/National Institute of Health, Baltimore, MD, USA
| | - Douglas R Stewart
- Clinical Genetics Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute; NIH, Bethesda, MD, USA
| | - Stella Koutros
- Occupational and Environmental Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute; NIH, Bethesda, MD, USA
| | - Alisa M Goldstein
- Clinical Genetics Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute; NIH, Bethesda, MD, USA
| | - Stephen J Chanock
- Division of Cancer Epidemiology and Genetics, National Cancer Institute; NIH, Bethesda, MD, USA
| | - Neil E Caporaso
- Occupational and Environmental Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute; NIH, Bethesda, MD, USA
| | - Margaret A Tucker
- Human Genetics Program, Division of Cancer Epidemiology and Genetics, National Cancer Institute; NIH, Bethesda, MD, USA
| | - Lynn R Goldin
- Integrative Tumor Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute; NIH, Bethesda, MD, USA
| | - Yie Liu
- Laboratory of Molecular Gerontology, National Institute on Aging/National Institute of Health, Baltimore, MD, USA
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Li H, Wei C, Zhou R, Wang B, Zhang Y, Shao C, Luo Y. Mouse models in modeling aging and cancer. Exp Gerontol 2019; 120:88-94. [PMID: 30876950 DOI: 10.1016/j.exger.2019.03.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Revised: 01/19/2019] [Accepted: 03/05/2019] [Indexed: 02/04/2023]
Abstract
Mouse models have been widely used in the research of human diseases. Aging, just as cancer, is influenced by the interaction of various genetic and environmental factors. Currently, aging could be induced by many mechanism, including telomere dysfunction, oxidase stress, DNA damage and epigenetic changes. Many of these genetic pathways are also shared by aging and cancer. The mouse models generated to study these pathways might manifest either aging or cancer phenotypes, sometimes both, which in deed has worked as a good model system in understanding the correlation between aging and cancer. Here, we reviewed these mouse models that were generated to model aging or cancer. These mouse models might help us put those related pathways in context and discover essential interactions in cancer and aging regulation.
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Affiliation(s)
- Haili Li
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650500, China; Lab of Molecular Genetics of Aging & Tumor, Medical School, Kunming University of Science and Technology, Kunming, Yunnan 650500, China
| | - Chuanyu Wei
- Lab of Molecular Genetics of Aging & Tumor, Medical School, Kunming University of Science and Technology, Kunming, Yunnan 650500, China
| | - Ruoyu Zhou
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650500, China; Lab of Molecular Genetics of Aging & Tumor, Medical School, Kunming University of Science and Technology, Kunming, Yunnan 650500, China
| | - Boyuan Wang
- Lab of Molecular Genetics of Aging & Tumor, Medical School, Kunming University of Science and Technology, Kunming, Yunnan 650500, China
| | - Yongjin Zhang
- Lab of Molecular Genetics of Aging & Tumor, Medical School, Kunming University of Science and Technology, Kunming, Yunnan 650500, China
| | - Chihao Shao
- Lab of Molecular Genetics of Aging & Tumor, Medical School, Kunming University of Science and Technology, Kunming, Yunnan 650500, China
| | - Ying Luo
- Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650500, China; Lab of Molecular Genetics of Aging & Tumor, Medical School, Kunming University of Science and Technology, Kunming, Yunnan 650500, China.
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Aksenova AY, Mirkin SM. At the Beginning of the End and in the Middle of the Beginning: Structure and Maintenance of Telomeric DNA Repeats and Interstitial Telomeric Sequences. Genes (Basel) 2019; 10:genes10020118. [PMID: 30764567 PMCID: PMC6410037 DOI: 10.3390/genes10020118] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 01/30/2019] [Accepted: 01/30/2019] [Indexed: 02/07/2023] Open
Abstract
Tandem DNA repeats derived from the ancestral (TTAGGG)n run were first detected at chromosome ends of the majority of living organisms, hence the name telomeric DNA repeats. Subsequently, it has become clear that telomeric motifs are also present within chromosomes, and they were suitably called interstitial telomeric sequences (ITSs). It is well known that telomeric DNA repeats play a key role in chromosome stability, preventing end-to-end fusions and precluding the recurrent DNA loss during replication. Recent data suggest that ITSs are also important genomic elements as they confer its karyotype plasticity. In fact, ITSs appeared to be among the most unstable microsatellite sequences as they are highly length polymorphic and can trigger chromosomal fragility and gross chromosomal rearrangements. Importantly, mechanisms responsible for their instability appear to be similar to the mechanisms that maintain the length of genuine telomeres. This review compares the mechanisms of maintenance and dynamic properties of telomeric repeats and ITSs and discusses the implications of these dynamics on genome stability.
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Affiliation(s)
- Anna Y Aksenova
- Laboratory of Amyloid Biology, St. Petersburg State University, 199034 St. Petersburg, Russia.
| | - Sergei M Mirkin
- Department of Biology, Tufts University, Medford, MA 02421, USA.
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Shoeb M, Mustafa GM, Joseph P, Umbright C, Kodali V, Roach KA, Meighan T, Roberts JR, Erdely A, Antonini JM. Initiation of Pulmonary Fibrosis after Silica Inhalation in Rats is linked with Dysfunctional Shelterin Complex and DNA Damage Response. Sci Rep 2019; 9:471. [PMID: 30679488 PMCID: PMC6346028 DOI: 10.1038/s41598-018-36712-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 11/19/2018] [Indexed: 12/16/2022] Open
Abstract
Occupational exposure to silica has been observed to cause pulmonary fibrosis and lung cancer through complex mechanisms. Telomeres, the nucleoprotein structures with repetitive (TTAGGG) sequences at the end of chromosomes, are a molecular "clock of life", and alterations are associated with chronic disease. The shelterin complex (POT1, TRF1, TRF2, Tin2, Rap1, and POT1 and TPP1) plays an important role in maintaining telomere length and integrity, and any alteration in telomeres may activate DNA damage response (DDR) machinery resulting in telomere attrition. The goal of this study was to assess the effect of silica exposure on the regulation of the shelterin complex in an animal model. Male Fisher 344 rats were exposed by inhalation to Min-U-Sil 5 silica for 3, 6, or 12 wk at a concentration of 15 mg/m3 for 6 hr/d for 5 consecutive d/wk. Expression of shelterin complex genes was assessed in the lungs at 16 hr after the end of each exposure. Also, the relationship between increased DNA damage protein (γH2AX) and expression of silica-induced fibrotic marker, αSMA, was evaluated. Our findings reveal new information about the dysregulation of shelterin complex after silica inhalation in rats, and how this pathway may lead to the initiation of silica-induced pulmonary fibrosis.
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Affiliation(s)
- Mohammad Shoeb
- Centers for Disease Control and Prevention, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV, 26505, USA.
| | - Gul M Mustafa
- Centers for Disease Control and Prevention, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV, 26505, USA
| | - Pius Joseph
- Centers for Disease Control and Prevention, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV, 26505, USA
| | - Christina Umbright
- Centers for Disease Control and Prevention, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV, 26505, USA
| | - Vamsi Kodali
- Centers for Disease Control and Prevention, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV, 26505, USA
| | - Katherine A Roach
- Centers for Disease Control and Prevention, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV, 26505, USA
| | - Terence Meighan
- Centers for Disease Control and Prevention, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV, 26505, USA
| | - Jenny R Roberts
- Centers for Disease Control and Prevention, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV, 26505, USA
| | - Aaron Erdely
- Centers for Disease Control and Prevention, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV, 26505, USA
| | - James M Antonini
- Centers for Disease Control and Prevention, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV, 26505, USA
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Tamura R, Nakaoka H, Yoshihara K, Mori Y, Yachida N, Nishikawa N, Motoyama T, Okuda S, Inoue I, Enomoto T. Novel MXD4-NUTM1 fusion transcript identified in primary ovarian undifferentiated small round cell sarcoma. Genes Chromosomes Cancer 2018; 57:557-563. [PMID: 30338611 PMCID: PMC6221051 DOI: 10.1002/gcc.22668] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2018] [Revised: 06/21/2018] [Accepted: 07/04/2018] [Indexed: 12/20/2022] Open
Abstract
Primary ovarian sarcomas are extremely rare tumors, and their genomic and transcriptomic alterations remain to be elucidated. We performed whole exome sequencing of primary tumor and matched normal blood samples derived from one patient with ovarian undifferentiated small round cell sarcoma. We identified 8 nonsynonymous somatic mutations, and all mutations were missense or nonsense changes. Next, we performed RNA sequencing of the tumor sample and identified two in-frame fusion transcripts: MXD4-NUTM1 and ARL6-POT1. Most NUTM1 exons were retained in the MXD4-NUTM1 fusion transcript, and we confirmed an increase in NUTM1 mRNA and protein expression in tumor tissue. Further genomic and transcriptomic analyses might lead to the development of new therapeutic strategies based on the molecular characteristics of ovarian undifferentiated small round cell sarcoma.
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Affiliation(s)
- Ryo Tamura
- Department of Obstetrics and GynecologyNiigata University Graduate School of Medical and Dental SciencesNiigataJapan
| | - Hirofumi Nakaoka
- Division of Human GeneticsNational Institute of GeneticsMishimaJapan
| | - Kosuke Yoshihara
- Department of Obstetrics and GynecologyNiigata University Graduate School of Medical and Dental SciencesNiigataJapan
| | - Yutaro Mori
- Department of Obstetrics and GynecologyNiigata University Graduate School of Medical and Dental SciencesNiigataJapan
| | - Nozomi Yachida
- Department of Obstetrics and GynecologyNiigata University Graduate School of Medical and Dental SciencesNiigataJapan
| | - Nobumichi Nishikawa
- Department of Obstetrics and GynecologyNiigata University Graduate School of Medical and Dental SciencesNiigataJapan
| | - Teiichi Motoyama
- Department of Molecular and Diagnostic PathologyNiigata University Graduate School of Medical and Dental SciencesNiigataJapan
| | - Shujiro Okuda
- Department of BioinformaticsNiigata University Graduate School of Medical and Dental SciencesNiigataJapan
| | - Ituro Inoue
- Division of Human GeneticsNational Institute of GeneticsMishimaJapan
| | - Takayuki Enomoto
- Department of Obstetrics and GynecologyNiigata University Graduate School of Medical and Dental SciencesNiigataJapan
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Amir M, Kumar V, Dohare R, Islam A, Ahmad F, Hassan MI. Sequence, structure and evolutionary analysis of cold shock domain proteins, a member of OB fold family. J Evol Biol 2018; 31:1903-1917. [PMID: 30267552 DOI: 10.1111/jeb.13382] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2018] [Revised: 09/20/2018] [Accepted: 09/24/2018] [Indexed: 11/28/2022]
Abstract
The cold shock domain (CSD) belongs to the oligosaccharide/oligonucleotide-binding fold superfamily which is highly conserved from prokaryotes to higher eukaryotes, and appears to function as RNA chaperones. CSD is involved in diverse cellular processes, including adaptation to low temperatures, nutrient stress, cellular growth and developmental processes. Structural Classification of Proteins (SCOP) database broadly classifies OB fold proteins into 18 different superfamilies, including nucleic acid-binding superfamily (NAB). The NAB is further divided into 17 families together with cold shock DNA-binding protein family (CSDB). The CSDB have more than 240 000 sequences in UniProt database consisting of 32 domains including CSD. Among these domains, CSD is the second largest sequence contributor (> 40 398 sequences). Herein, we have systematically analysed the relative abundance and distribution of CSD proteins based on sequences, structures, repeats and gene ontology (GO) molecular functions in all domains of life. Analysis of sequence distribution suggesting that CSDs are largely found in bacteria (83-94%) with single CSD repeat. However, repeat distribution in eukaryota varies from 1 to 5 in combination with other auxiliary domain that makes CSD proteins functionally more diverse compared to the bacterial counterparts. Further, analysis of repeats distributions on evolutionary scale suggest that existence of CSD in multiple repeats is mainly driven through speciation, gene shuffling and gene duplication events.
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Affiliation(s)
- Mohd Amir
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, India
| | - Vijay Kumar
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, India.,Amity Institute of Neuropsychology & Neurosciences, Amity University Noida, UP, India
| | - Ravins Dohare
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, India
| | - Asimul Islam
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, India
| | - Faizan Ahmad
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, India
| | - Md Imtaiyaz Hassan
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, India
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Nguyen LN, Zhao J, Cao D, Dang X, Wang L, Lian J, Zhang Y, Jia Z, Wu XY, Morrison Z, Xie Q, Ji Y, Zhang Z, El Gazzar M, Ning S, Moorman JP, Yao ZQ. Inhibition of TRF2 accelerates telomere attrition and DNA damage in naïve CD4 T cells during HCV infection. Cell Death Dis 2018; 9:900. [PMID: 30185784 PMCID: PMC6125360 DOI: 10.1038/s41419-018-0897-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 07/02/2018] [Accepted: 07/09/2018] [Indexed: 12/14/2022]
Abstract
T cells play a crucial role in viral clearance and vaccine responses; however, the mechanisms that regulate their homeostasis during viral infections remain unclear. In this study, we investigated the machineries of T-cell homeostasis and telomeric DNA damage using a human model of hepatitis C virus (HCV) infection. We found that naïve CD4 T cells in chronically HCV-infected patients (HCV T cells) were significantly reduced due to apoptosis compared with age-matched healthy subjects (HSs). These HCV T cells were not only senescent, as demonstrated by overexpression of aging markers and particularly shortened telomeres; but also DNA damaged, as evidenced by increased dysfunctional telomere-induced foci (TIF). Mechanistically, the telomere shelterin protein, in particular telomeric repeat binding factor 2 (TRF2) that functions to protect telomeres from DNA damage, was significantly inhibited posttranscriptionally via the p53-dependent Siah-1a ubiquitination. Importantly, knockdown of TRF2 in healthy T cells resulted in increases in telomeric DNA damage and T-cell apoptosis, whereas overexpression of TRF2 in HCV T cells alleviated telomeric DNA damage and T-cell apoptosis. To the best of our knowledge, this is the first report revealing that inhibition of TRF2 promotes T-cell telomere attrition and telomeric DNA damage that accelerates T-cell senescent and apoptotic programs, which contribute to naïve T-cell loss during viral infection. Thus, restoring the impaired T-cell telomeric shelterin machinery may offer a new strategy to improve immunotherapy and vaccine response against human viral diseases.
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Affiliation(s)
- Lam Nhat Nguyen
- Center of Excellence in Inflammation, Infectious Disease and Immunity, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, 37614, USA
- Division of Infectious, Inflammatory and Immunologic Diseases, Department of Internal Medicine, Quillen College of Medicine, ETSU, Johnson City, TN, 37614, USA
| | - Juan Zhao
- Center of Excellence in Inflammation, Infectious Disease and Immunity, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, 37614, USA
- Division of Infectious, Inflammatory and Immunologic Diseases, Department of Internal Medicine, Quillen College of Medicine, ETSU, Johnson City, TN, 37614, USA
| | - Dechao Cao
- Center of Excellence in Inflammation, Infectious Disease and Immunity, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, 37614, USA
- Division of Infectious, Inflammatory and Immunologic Diseases, Department of Internal Medicine, Quillen College of Medicine, ETSU, Johnson City, TN, 37614, USA
| | - Xindi Dang
- Center of Excellence in Inflammation, Infectious Disease and Immunity, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, 37614, USA
- Division of Infectious, Inflammatory and Immunologic Diseases, Department of Internal Medicine, Quillen College of Medicine, ETSU, Johnson City, TN, 37614, USA
| | - Ling Wang
- Center of Excellence in Inflammation, Infectious Disease and Immunity, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, 37614, USA
- Division of Infectious, Inflammatory and Immunologic Diseases, Department of Internal Medicine, Quillen College of Medicine, ETSU, Johnson City, TN, 37614, USA
| | - Jianqi Lian
- Department of Infectious Diseases, Tangdu Hospital, The Fourth Military Medical University, Xi'an, China
| | - Ying Zhang
- Department of Infectious Diseases, Tangdu Hospital, The Fourth Military Medical University, Xi'an, China
| | - Zhansheng Jia
- Department of Infectious Diseases, Tangdu Hospital, The Fourth Military Medical University, Xi'an, China
| | - Xiao Y Wu
- Center of Excellence in Inflammation, Infectious Disease and Immunity, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, 37614, USA
- Division of Infectious, Inflammatory and Immunologic Diseases, Department of Internal Medicine, Quillen College of Medicine, ETSU, Johnson City, TN, 37614, USA
| | - Zheng Morrison
- Center of Excellence in Inflammation, Infectious Disease and Immunity, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, 37614, USA
- Division of Infectious, Inflammatory and Immunologic Diseases, Department of Internal Medicine, Quillen College of Medicine, ETSU, Johnson City, TN, 37614, USA
| | - Qian Xie
- Center of Excellence in Inflammation, Infectious Disease and Immunity, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, 37614, USA
| | - Yingjie Ji
- Research Center for Clinical and Translational Medicine, Beijing 302 Hospital, Beijing, China
| | - Zheng Zhang
- Research Center for Clinical and Translational Medicine, Beijing 302 Hospital, Beijing, China
| | - Mohamed El Gazzar
- Center of Excellence in Inflammation, Infectious Disease and Immunity, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, 37614, USA
| | - Shunbin Ning
- Center of Excellence in Inflammation, Infectious Disease and Immunity, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, 37614, USA
- Division of Infectious, Inflammatory and Immunologic Diseases, Department of Internal Medicine, Quillen College of Medicine, ETSU, Johnson City, TN, 37614, USA
| | - Jonathan P Moorman
- Center of Excellence in Inflammation, Infectious Disease and Immunity, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, 37614, USA
- Division of Infectious, Inflammatory and Immunologic Diseases, Department of Internal Medicine, Quillen College of Medicine, ETSU, Johnson City, TN, 37614, USA
- Department of Veterans Affairs, Hepatitis (HCV/HBV/HIV) Program, James H. Quillen VA Medical Center, Johnson City, TN, 37614, USA
| | - Zhi Q Yao
- Center of Excellence in Inflammation, Infectious Disease and Immunity, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, 37614, USA.
- Division of Infectious, Inflammatory and Immunologic Diseases, Department of Internal Medicine, Quillen College of Medicine, ETSU, Johnson City, TN, 37614, USA.
- Department of Veterans Affairs, Hepatitis (HCV/HBV/HIV) Program, James H. Quillen VA Medical Center, Johnson City, TN, 37614, USA.
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The role of telomere binding molecules for normal and abnormal hematopoiesis. Int J Hematol 2018; 107:646-655. [DOI: 10.1007/s12185-018-2432-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 03/12/2018] [Indexed: 11/26/2022]
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Time-Dependent Effects of POT1 Knockdown on Proliferation, Tumorigenicity, and HDACi Response of SK-OV3 Ovarian Cancer Cells. BIOMED RESEARCH INTERNATIONAL 2018; 2018:7184253. [PMID: 29546066 PMCID: PMC5818924 DOI: 10.1155/2018/7184253] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2017] [Accepted: 12/21/2017] [Indexed: 02/07/2023]
Abstract
The roles of protection of telomeres 1 (POT1) in human ovarian cancer have not been fully elucidated. Here, we investigated the impact of POT1 knockdown (POT1-KD) on in vitro cell proliferation, tumorigenesis, and histone deacetylase inhibitor (HDACi) response in human ovarian cancer-derived SK-OV3 cells. The POT1 gene was knocked down by infection with POT1 lenti-shRNA. POT1, c-Myc, and hTERT mRNA levels and relative telomere length were determined by qRT-PCR; POT1 protein levels were determined by western blot. The relative telomerase activity levels were detected using qTRAP; cell proliferation was assessed using cumulative population doubling (cPD) experiments. Cell tumorigenicity was evaluated by anchorage-independent cell growth assays, and cell response to HDACi was determined by luminescence cell viability assays. Results indicate that lenti-shRNA-mediated POT1-KD significantly reduced POT1 mRNA and protein expression. POT1-KD immediately downregulated c-Myc expression, which led to the inhibition of cell proliferation, tumorigenesis, and HDACi response. However, after brief suppression, c-Myc expression increased in the medium term, which resulted in enhanced cell proliferation, tumorigenesis, and HDACi response in the POT1-KD cells. Furthermore, we discovered that c-Myc regulated cell proliferation and tumorigenesis via hTERT/telomerase/telomere pathway.
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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.
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