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Sanchez SE, Gu J, Golla A, Martin A, Shomali W, Hockemeyer D, Savage SA, Artandi SE. Digital telomere measurement by long-read sequencing distinguishes healthy aging from disease. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.29.569263. [PMID: 38077053 PMCID: PMC10705489 DOI: 10.1101/2023.11.29.569263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/23/2023]
Abstract
Telomere length is an important biomarker of organismal aging and cellular replicative potential, but existing measurement methods are limited in resolution and accuracy. Here, we deploy digital telomere measurement by nanopore sequencing to understand how distributions of human telomere length change with age and disease. We measure telomere attrition and de novo elongation with unprecedented resolution in genetically defined populations of human cells, in blood cells from healthy donors and in blood cells from patients with genetic defects in telomere maintenance. We find that human aging is accompanied by a progressive loss of long telomeres and an accumulation of shorter telomeres. In patients with defects in telomere maintenance, the accumulation of short telomeres is more pronounced and correlates with phenotypic severity. We apply machine learning to train a binary classification model that distinguishes healthy individuals from those with telomere biology disorders. This sequencing and bioinformatic pipeline will advance our understanding of telomere maintenance mechanisms and the use of telomere length as a clinical biomarker of aging and disease.
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Affiliation(s)
- Santiago E. Sanchez
- Stanford Cancer Institute, Stanford University School of Medicine; Stanford, CA, USA
- Cancer Biology Program, Stanford University School of Medicine; Stanford, CA, USA
- Medical Scientist Training Program, Stanford University; Stanford CA, USA
| | - Jessica Gu
- Stanford Cancer Institute, Stanford University School of Medicine; Stanford, CA, USA
- Department of Medicine, Stanford University School of Medicine; Stanford, CA, USA
- Department of Biochemistry, Stanford University School of Medicine; Stanford, CA, USA
| | - Anudeep Golla
- Stanford Cancer Institute, Stanford University School of Medicine; Stanford, CA, USA
| | - Annika Martin
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA
| | - William Shomali
- Department of Medicine, Stanford University School of Medicine; Stanford, CA, USA
| | - Dirk Hockemeyer
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA
- Chan Zuckerberg Biohub, San Francisco, CA
- Innovative Genomics Institute, University of California, Berkeley, Berkeley, CA
| | - Sharon A. Savage
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland, USA
| | - Steven E. Artandi
- Stanford Cancer Institute, Stanford University School of Medicine; Stanford, CA, USA
- Department of Medicine, Stanford University School of Medicine; Stanford, CA, USA
- Department of Biochemistry, Stanford University School of Medicine; Stanford, CA, USA
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Yegorov YE. Olovnikov, Telomeres, and Telomerase. Is It Possible to Prolong a Healthy Life? BIOCHEMISTRY. BIOKHIMIIA 2023; 88:1704-1718. [PMID: 38105192 DOI: 10.1134/s0006297923110032] [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: 07/20/2023] [Revised: 08/29/2023] [Accepted: 08/31/2023] [Indexed: 12/19/2023]
Abstract
The science of telomeres and telomerase has made tremendous progress in recent decades. In this review, we consider it first in a historical context (the Carrel-Hayflick-Olovnikov-Blackburn chain of discoveries) and then review current knowledge on the telomere structure and dynamics in norm and pathology. Central to the review are consequences of the telomere shortening, including telomere position effects, DNA damage signaling, and increased genetic instability. Cell senescence and role of telomere length in its development are discussed separately. Therapeutic aspects and risks of telomere lengthening methods including use of telomerase and other approaches are also discussed.
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Affiliation(s)
- Yegor E Yegorov
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, 119991, Russia.
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Liu W, Chen S, Xie W, Wang Q, Luo Q, Huang M, Gu M, Lan P, Chen D. MCCC2 is a novel mediator between mitochondria and telomere and functions as an oncogene in colorectal cancer. Cell Mol Biol Lett 2023; 28:80. [PMID: 37828426 PMCID: PMC10571261 DOI: 10.1186/s11658-023-00487-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Accepted: 09/04/2023] [Indexed: 10/14/2023] Open
Abstract
BACKGROUND The mitochondrial gene MCCC2, a subunit of the heterodimer of 3-methylcrotonyl-CoA carboxylase, plays a pivotal role in catabolism of leucine and isovaleric acid. The molecular mechanisms and prognostic value still need to be explored in the context of specific cancers, including colorectal cancer (CRC). METHODS In vitro and in vivo cell-based assays were performed to explore the role of MCCC2 in CRC cell proliferation, invasion, and migration. Mitochondrial morphology, membrane potential, intracellular reactive oxygen species (ROS), telomerase activity, and telomere length were examined and analyzed accordingly. Protein complex formation was detected by co-immunoprecipitation (CO-IP). Mitochondrial morphology was observed by transmission electron microscopy (TEM). The Cancer Genome Atlas (TCGA) CRC cohort analysis, qRT-PCR, and immunohistochemistry (IHC) were used to examine the MCCC2 expression level. The association between MCCC2 expression and various clinical characteristics was analyzed by chi-square tests. CRC patients' overall survival (OS) was analyzed by Kaplan-Meier analysis. RESULTS Ectopic overexpression of MCCC2 promoted cell proliferation, invasion, and migration, while MCCC2 knockdown (KD) or knockout (KO) inhibited cell proliferation, invasion, and migration. MCCC2 KD or KO resulted in reduced mitochondria numbers, but did not affect the gross ATP production in the cells. Mitochondrial fusion markers MFN1, MFN2, and OPA1 were all upregulated in MCCC2 KD or KO cells, which is in line with a phenomenon of more prominent mitochondrial fusion. Interestingly, telomere lengths of MCCC2 KD or KO cells were reduced more than control cells. Furthermore, we found that MCCC2 could specifically form a complex with telomere binding protein TRF2, and MCCC2 KD or KO did not affect the expression or activity of telomerase reverse transcriptase (TERT). Finally, MCCC2 expression was heightened in CRC, and patients with higher MCCC2 expression had favorable prognosis. CONCLUSIONS Together, we identified MCCC2 as a novel mediator between mitochondria and telomeres, and provided an additional biomarker for CRC stratification.
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Affiliation(s)
- Wanjun Liu
- Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Diseases, The Sixth Affiliated Hospital, Sun Yat-sen University, 26 Yuancun Er Heng Road, Guangzhou, 510655, Guangdong, China
- Biomedical Innovation Center, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Si Chen
- Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Diseases, The Sixth Affiliated Hospital, Sun Yat-sen University, 26 Yuancun Er Heng Road, Guangzhou, 510655, Guangdong, China
| | - Wenqing Xie
- Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Diseases, The Sixth Affiliated Hospital, Sun Yat-sen University, 26 Yuancun Er Heng Road, Guangzhou, 510655, Guangdong, China
- Biomedical Innovation Center, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Qian Wang
- Department of Intensive Care Unit, The Sixth Affiliated Hospital, Sun Yat-sen University, 26 Yuancun Er Heng Road, Guangzhou, 510655, China
| | - Qianxin Luo
- Department of Intensive Care Unit, The Sixth Affiliated Hospital, Sun Yat-sen University, 26 Yuancun Er Heng Road, Guangzhou, 510655, China
| | - Minghan Huang
- Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Diseases, The Sixth Affiliated Hospital, Sun Yat-sen University, 26 Yuancun Er Heng Road, Guangzhou, 510655, Guangdong, China
- Biomedical Innovation Center, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Minyi Gu
- Biomedical Innovation Center, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
- Scientific Journal Center, The Sixth Affiliated Hospital, Sun Yat-sen University, 26 Yuancun Er Heng Road, Guangzhou, 510655, China
| | - Ping Lan
- Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Diseases, The Sixth Affiliated Hospital, Sun Yat-sen University, 26 Yuancun Er Heng Road, Guangzhou, 510655, Guangdong, China.
- Department of General Surgery, The Sixth Affiliated Hospital, Sun Yat-sen University, 26 Yuancun Er Heng Road, Guangzhou, 510655, China.
| | - Daici Chen
- Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Diseases, The Sixth Affiliated Hospital, Sun Yat-sen University, 26 Yuancun Er Heng Road, Guangzhou, 510655, Guangdong, China.
- Biomedical Innovation Center, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, China.
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Liu J, Zheng T, Chen D, Huang J, Zhao Y, Ma W, Liu H. RBMX involves in telomere stability maintenance by regulating TERRA expression. PLoS Genet 2023; 19:e1010937. [PMID: 37756323 PMCID: PMC10529574 DOI: 10.1371/journal.pgen.1010937] [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: 01/18/2023] [Accepted: 08/23/2023] [Indexed: 09/29/2023] Open
Abstract
Telomeric repeat-containing RNA (TERRA) is a class of long noncoding RNAs (lncRNAs) that are transcribed from subtelomeric to telomeric region of chromosome ends. TERRA is prone to form R-loop structures at telomeres by invading into telomeric DNA. Excessive telomere R-loops result in telomere instability, so the TERRA level needs to be delicately modulated. However, the molecular mechanisms and factors controlling TERRA level are still largely unknown. In this study, we report that the RNA binding protein RBMX is a novel regulator of TERRA level and telomere integrity. The expression level of TERRA is significantly elevated in RBMX depleted cells, leading to enhanced telomere R-loop formation, replication stress, and telomere instability. We also found that RBMX binds to TERRA and the nuclear exosome targeting protein ZCCHC8 simultaneously, and that TERRA degradation slows down upon RBMX depletion, implying that RBMX promotes TERRA degradation by regulating its transportation to the nuclear exosome, which decays nuclear RNAs. Altogether, these findings uncover a new role of RBMX in TERRA expression regulation and telomere integrity maintenance, and raising RBMX as a potential target of cancer therapy.
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Affiliation(s)
- Jingfan Liu
- MOE Key Laboratory of Gene Function and Regulation, School of Life Sciences, Sun Yat-sen University, Guangzhou, People’s Republic of China
| | - Tian Zheng
- MOE Key Laboratory of Gene Function and Regulation, School of Life Sciences, Sun Yat-sen University, Guangzhou, People’s Republic of China
- NHC Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People’s Republic of China
| | - Dandan Chen
- MOE Key Laboratory of Gene Function and Regulation, School of Life Sciences, Sun Yat-sen University, Guangzhou, People’s Republic of China
| | - Junjiu Huang
- MOE Key Laboratory of Gene Function and Regulation, School of Life Sciences, Sun Yat-sen University, Guangzhou, People’s Republic of China
| | - Yong Zhao
- MOE Key Laboratory of Gene Function and Regulation, School of Life Sciences, Sun Yat-sen University, Guangzhou, People’s Republic of China
| | - Wenbin Ma
- MOE Key Laboratory of Gene Function and Regulation, School of Life Sciences, Sun Yat-sen University, Guangzhou, People’s Republic of China
| | - Haiying Liu
- MOE Key Laboratory of Gene Function and Regulation, School of Life Sciences, Sun Yat-sen University, Guangzhou, People’s Republic of China
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Abstract
It has been known for decades that telomerase extends the 3' end of linear eukaryotic chromosomes and dictates the telomeric repeat sequence based on the template in its RNA. However, telomerase does not mitigate sequence loss at the 5' ends of chromosomes, which results from lagging strand DNA synthesis and nucleolytic processing. Therefore, a second enzyme is needed to keep telomeres intact: DNA polymerase α/Primase bound to Ctc1-Stn1-Ten1 (CST). CST-Polα/Primase maintains telomeres through a fill-in reaction that replenishes the lost sequences at the 5' ends. CST not only serves to maintain telomeres but also determines their length by keeping telomerase from overelongating telomeres. Here we discuss recent data on the evolution, structure, function, and recruitment of mammalian CST-Polα/Primase, highlighting the role of this complex and telomere length control in human disease.
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Affiliation(s)
- Sarah W Cai
- Laboratory for Cell Biology and Genetics, The Rockefeller University, New York, New York 10065, USA
| | - Titia de Lange
- Laboratory for Cell Biology and Genetics, The Rockefeller University, New York, New York 10065, USA
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6
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Sagris M, Theofilis P, Antonopoulos AS, Tsioufis K, Tousoulis D. Telomere Length: A Cardiovascular Biomarker and a Novel Therapeutic Target. Int J Mol Sci 2022; 23:ijms232416010. [PMID: 36555658 PMCID: PMC9781338 DOI: 10.3390/ijms232416010] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 12/04/2022] [Accepted: 12/11/2022] [Indexed: 12/23/2022] Open
Abstract
Coronary artery disease (CAD) is a multifactorial disease with a high prevalence, particularly in developing countries. Currently, the investigation of telomeres as a potential tool for the early detection of the atherosclerotic disease seems to be a promising method. Telomeres are repetitive DNA sequences located at the extremities of chromosomes that maintain genetic stability. Telomere length (TL) has been associated with several human disorders and diseases while its attrition rate varies significantly in the population. The rate of TL shortening ranges between 20 and 50 bp and is affected by factors such as the end-replication phenomenon, oxidative stress, and other DNA-damaging agents. In this review, we delve not only into the pathophysiology of TL shortening but also into its association with cardiovascular disease and the progression of atherosclerosis. We also provide current and future treatment options based on TL and telomerase function, trying to highlight the importance of these cutting-edge developments and their clinical relevance.
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Pereiro X, Beriain S, Rodriguez L, Roiz-Valle D, Ruzafa N, Vecino E. Characteristics of Whale Müller Glia in Primary and Immortalized Cultures. Front Neurosci 2022; 16:854278. [PMID: 35360150 PMCID: PMC8964101 DOI: 10.3389/fnins.2022.854278] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 02/22/2022] [Indexed: 11/16/2022] Open
Abstract
Müller cells are the principal glial cells in the retina and they assume many of the functions carried out by astrocytes, oligodendrocytes and ependymal cells in other regions of the central nervous system. Müller cells express growth factors, neurotransmitter transporters and antioxidant agents that could fulfill important roles in preventing excitotoxic damage to retinal neurons. Vertebrate Müller cells are well-defined cells, characterized by a common set of features throughout the phylum. Nevertheless, several major differences have been observed among the Müller cells in distinct vertebrates, such as neurogenesis, the capacity to reprogram fish Müller glia to neurons. Here, the Müller glia of the largest adult mammal in the world, the whale, have been analyzed, and given the difficulties in obtaining cetacean cells for study, these whale glia were analyzed both in primary cultures and as immortalized whale Müller cells. After isolating the retina from the eye of a beached sei whale (Balaenoptera borealis), primary Müller cell cultures were established and once the cultures reached confluence, half of the cultures were immortalized with the simian virus 40 (SV40) large T-antigen commonly used to immortalize human cell lines. The primary cell cultures were grown until cells reached senescence. Expression of the principal molecular markers of Müller cells (GFAP, Vimentin and Glutamine synthetase) was studied in both primary and immortalized cells at each culture passage. Proliferation kinetics of the cells were analyzed by time-lapse microscopy: the time between divisions, the time that cells take to divide, and the proportion of dividing cells in the same field. The karyotypes of the primary and immortalized whale Müller cells were also characterized. Our results shown that W21M proliferate more rapidly and they have a stable karyotype. W21M cells display a heterogeneous cell morphology, less motility and a distinctive expression of some typical molecular markers of Müller cells, with an increase in dedifferentiation markers like α-SMA and β-III tubulin, while they preserve their GS expression depending on the culture passage. Here we also discuss the possible influence of the animal's age and size on these cells, and on their senescence.
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Affiliation(s)
- Xandra Pereiro
- Experimental Ophthalmo-Biology Group, Department of Cell Biology and Histology, University of Basque Country UPV/EHU, Leioa, Spain
- Begiker-Ophthalmology Research Group, BioCruces Health Research Institute, Cruces Hospital, Barakaldo, Spain
| | - Sandra Beriain
- Experimental Ophthalmo-Biology Group, Department of Cell Biology and Histology, University of Basque Country UPV/EHU, Leioa, Spain
| | - Lara Rodriguez
- Experimental Ophthalmo-Biology Group, Department of Cell Biology and Histology, University of Basque Country UPV/EHU, Leioa, Spain
| | - David Roiz-Valle
- Department of Biochemistry and Molecular Biology, University Institute of Oncology (IUOPA), University of Oviedo, Oviedo, Spain
| | - Noelia Ruzafa
- Experimental Ophthalmo-Biology Group, Department of Cell Biology and Histology, University of Basque Country UPV/EHU, Leioa, Spain
- Begiker-Ophthalmology Research Group, BioCruces Health Research Institute, Cruces Hospital, Barakaldo, Spain
| | - Elena Vecino
- Experimental Ophthalmo-Biology Group, Department of Cell Biology and Histology, University of Basque Country UPV/EHU, Leioa, Spain
- Begiker-Ophthalmology Research Group, BioCruces Health Research Institute, Cruces Hospital, Barakaldo, Spain
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8
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Lee RS, Zandi PP, Santos A, Aulinas A, Carey JL, Webb SM, McCaul ME, Resmini E, Wand GS. Cross-species Association Between Telomere Length and Glucocorticoid Exposure. J Clin Endocrinol Metab 2021; 106:e5124-e5135. [PMID: 34265046 PMCID: PMC8787853 DOI: 10.1210/clinem/dgab519] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Indexed: 12/12/2022]
Abstract
CONTEXT Chronic exposure to glucocorticoids (GCs) or stress increases the risk of medical disorders, including cardiovascular and neuropsychiatric disorders. GCs contribute to accelerated aging; however, while the link between chronic GC exposure and disease onset is well established, the underpinning mechanisms are not clear. OBJECTIVE We explored the potential nexus between GCs or stress exposure and telomere length. METHODS In addition to rats exposed to 3 weeks of chronic stress, an iatrogenic mouse model of Cushing syndrome (CS), and a mouse neuronal cell line, we studied 32 patients with CS and age-matched controls and another cohort of 75 healthy humans. RESULTS (1) Exposure to stress in rats was associated with a 54.5% (P = 0.036) reduction in telomere length in T cells. Genomic DNA (gDNA) extracted from the dentate gyrus of stressed and unstressed rats showed 43.2% reduction in telomere length (P = 0.006). (2) Mice exposed to corticosterone had a 61.4% reduction in telomere length in blood gDNA (P = 5.75 × 10-5) and 58.8% reduction in telomere length in the dentate gyrus (P = 0.002). (3) We observed a 40.8% reduction in the telomere length in patients with active CS compared to healthy controls (P = 0.006). There was a 17.8% reduction in telomere length in cured CS patients, which was not different from that of healthy controls (P = 0.08). For both cured and active CS, telomere length correlated significantly with duration of hypercortisolism (R2 = 0.22, P = 0.007). (4) There was a 27.6% reduction in telomere length between low and high tertiles in bedtime cortisol levels of healthy participants (P = 0.019). CONCLUSION Our findings demonstrate that exposure to stress and/or GCs is associated with shortened telomeres, which may be partially reversible.
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Affiliation(s)
- Richard S Lee
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA
| | - Peter P Zandi
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA
- Department of Mental Health, Johns Hopkins School of Public Health, Baltimore, MD 21205, USA
| | - Alicia Santos
- Endocrinology/Medicine Department, Hospital Sant Pau, Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBER-ER, Unit747), IIB-Sant Pau, ISCIII and Universitat Autònoma de Barcelona (UAB), Barcelona, Spain
| | - Anna Aulinas
- Endocrinology/Medicine Department, Hospital Sant Pau, Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBER-ER, Unit747), IIB-Sant Pau, ISCIII and Universitat Autònoma de Barcelona (UAB), Barcelona, Spain
| | - Jenny L Carey
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA
| | - Susan M Webb
- Endocrinology/Medicine Department, Hospital Sant Pau, Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBER-ER, Unit747), IIB-Sant Pau, ISCIII and Universitat Autònoma de Barcelona (UAB), Barcelona, Spain
| | - Mary E McCaul
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA
| | - Eugenia Resmini
- Correspondence: Eugenia Resmini, MD, PhD, Endocrinology/Medicine Department, Hospital Sant Pau, CIBER-ER, Unit747, IIB-Sant Pau, ISCIII, Universitat Autònoma de Barcelona (UAB), Barcelona, Spain.
| | - Gary S Wand
- Gary S. Wand, MD, Department of Medicine, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA.
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Kim YM, Hong S. Controversial roles of cold‑inducible RNA‑binding protein in human cancer (Review). Int J Oncol 2021; 59:91. [PMID: 34558638 DOI: 10.3892/ijo.2021.5271] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 09/06/2021] [Indexed: 11/05/2022] Open
Abstract
Cold‑inducible RNA‑binding protein (CIRBP) is a cold‑shock protein comprised of an RNA‑binding motif that is induced by several stressors, such as cold shock, UV radiation, nutrient deprivation, reactive oxygen species and hypoxia. CIRBP can modulate post‑transcriptional regulation of target mRNA, which is required to control DNA repair, circadian rhythms, cell growth, telomere integrity and cardiac physiology. In addition, the crucial function of CIRBP in various human diseases, including cancers and inflammatory disease, has been reported. Although CIRBP is primarily considered to be an oncogene, it may also serve a role in tumor suppression. In the present study, the controversial roles of CIRBP in various human cancers is summarized, with a focus on the interconnectivity between CIRBP and its target mRNAs involved in tumorigenesis. CIRBP may represent an important prognostic marker and therapeutic target for cancer therapy.
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Affiliation(s)
- Young-Mi Kim
- Department of Health Sciences and Technology, Gachon Advanced Institute for Health Sciences and Technology, Gachon University, Incheon 21999, Republic of Korea
| | - Suntaek Hong
- Department of Health Sciences and Technology, Gachon Advanced Institute for Health Sciences and Technology, Gachon University, Incheon 21999, Republic of Korea
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Zhang G, Zhang C, Leng D, Yan P, Wang Z, Zhang M, Wu Z. The non-canonical functions of telomerase reverse transcriptase gene GlTert on regulating fungal growth, oxidative stress, and ganoderic acid biosynthesis in Ganoderma lucidum. Appl Microbiol Biotechnol 2021; 105:7353-7365. [PMID: 34515845 DOI: 10.1007/s00253-021-11564-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 08/28/2021] [Accepted: 09/01/2021] [Indexed: 11/30/2022]
Abstract
The telomerase reverse transcriptase (TERT) is the core catalytic subunit of telomerase. Its canonical function is synthesizing telomeric repeats to maintain telomere length and chromosomal stability. Accumulating evidence suggests that TERT has other important fundamental functions in addition to its catalytic telomere repeat synthesis activity. However, the non-canonical roles of TERT independent of its enzymatic activity are not clear in filamentous fungi. In the present study, we characterized the GlTert gene in Ganoderma lucidum. The non-canonical roles of GlTert were explored using GlTert-silenced strains (Terti8 and Terti25) obtained by RNA interference. Silencing GlTert delayed the fungal growth, decreased the length between hyphal branches, and induced fungal resistance to oxidative stress in G. ludicum. Further examination revealed that the intracellular ROS (reactive oxygen species) levels were increased while the enzyme activities of the antioxidant systems (superoxide dismutase, catalase, glutathione peroxidase, and ascorbate peroxidase) were decreased in GlTert-silenced strains. In addition, silencing GlTert decreased the ganoderic acid (GA) biosynthesis of G. lucidum. Taken together, our results indicate that GlTert plays a fundamental function on fungal growth, oxidative stress, and GA biosynthesis in G. lucidum, providing new insights for the canonical functions of TERT in filamentous fungi. KEY POINTS: • GlTert affected fungal growth and hyphal branching of G. lucidum. • Silencing GlTert increased the intracellular ROS levels of G. lucidum. • GlTert regulated GA biosynthesis of G. lucidum.
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Affiliation(s)
- Guang Zhang
- College of Life Science and Technology, Henan Institute of Science and Technology, Xinxiang, 453003, Xinxiang, People's Republic of China.
- Collaborative Innovation Center of Modern Biological Breeding of Henan Province, Xinxiang, 453003, Xinxiang, People's Republic of China.
| | - Chaohui Zhang
- College of Life Science and Technology, Henan Institute of Science and Technology, Xinxiang, 453003, Xinxiang, People's Republic of China
- Collaborative Innovation Center of Modern Biological Breeding of Henan Province, Xinxiang, 453003, Xinxiang, People's Republic of China
| | - Doudou Leng
- College of Life Science and Technology, Henan Institute of Science and Technology, Xinxiang, 453003, Xinxiang, People's Republic of China
| | - Peng Yan
- College of Life Science and Technology, Henan Institute of Science and Technology, Xinxiang, 453003, Xinxiang, People's Republic of China
| | - Zhenhe Wang
- College of Life Science and Technology, Henan Institute of Science and Technology, Xinxiang, 453003, Xinxiang, People's Republic of China
| | - Mingxia Zhang
- College of Life Science and Technology, Henan Institute of Science and Technology, Xinxiang, 453003, Xinxiang, People's Republic of China
| | - Zhongwei Wu
- College of Life Science and Technology, Henan Institute of Science and Technology, Xinxiang, 453003, Xinxiang, People's Republic of China
- Collaborative Innovation Center of Modern Biological Breeding of Henan Province, Xinxiang, 453003, Xinxiang, People's Republic of China
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11
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Kan G, Wang Z, Sheng C, Yao C, Mao Y, Chen S. Inhibition of DKC1 induces telomere-related senescence and apoptosis in lung adenocarcinoma. J Transl Med 2021; 19:161. [PMID: 33879171 PMCID: PMC8056518 DOI: 10.1186/s12967-021-02827-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2020] [Accepted: 04/12/2021] [Indexed: 12/25/2022] Open
Abstract
Background Lung cancer is one of the most widely spread cancers in the world and half of the non-small cell lung cancers are lung adenocarcinoma (LUAD). Although there were several drugs been approved for LUAD therapy, a large portion of LUAD still cannot be effectively treated due to lack of available therapeutic targets. Here, we investigated the oncogenic roles of DKC1 in LUAD and its potential mechanism and explored the possibility of targeting DKC1 for LUAD therapy. Methods The Gene Expression Omnibus (GEO) and The Cancer Genome Atlas Program (TCGA) databases were used to examine the DKC1 transcript levels. Gene expression with clinical information from tissue microarray of LUAD were analyzed for associations between DKC1 expression and LUAD prognosis. In addition, loss- and gain-of-function assays were used for oncogenic function of DKC1 both in vitro and in vivo. Results DKC1 is overexpressed in LUAD compared with adjacent normal tissues. High expression of DKC1 predicts the poor overall survival. DKC1 knockdown in LUAD cell lines induced G1 phase arrest and inhibited cell proliferation. Ectopic expression of DKC1 could rescue the growth of LUAD cell lines. In addition, the abundance of DKC1 is positively correlated with telomerase RNA component (TERC) and telomerase reverse transcriptase (TERT) levels in LUAD. DKC1 downregulation resulted in decreased TERC expression, reduced telomerase activity and shorten telomere, and thus eventually led to cell senescence and apoptosis. Conclusions Our results show that high DKC1 expression indicates poor prognosis of LUAD and DKC1 downregulation could induce telomere-related cell senescence and apoptosis. This study suggests that DKC1 could serve as a candidate diagnostic biomarker and therapeutic target for LUAD. Supplementary Information The online version contains supplementary material available at 10.1186/s12967-021-02827-0.
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Affiliation(s)
- Guangyan Kan
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, 510060, Guangdong, People's Republic of China
| | - Ziyang Wang
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, 510060, Guangdong, People's Republic of China
| | - Chunjie Sheng
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, 510060, Guangdong, People's Republic of China
| | - Chen Yao
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, 510060, Guangdong, People's Republic of China
| | - Yizhi Mao
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, 510060, Guangdong, People's Republic of China
| | - Shuai Chen
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, 510060, Guangdong, People's Republic of China.
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12
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Bilateral telomerase-associated impacts of Spirulina platensis extracts: Activation versus inhibition. Eur J Integr Med 2021. [DOI: 10.1016/j.eujim.2021.101303] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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13
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Yegorov YE, Poznyak AV, Nikiforov NG, Starodubova AV, Orekhov AN. Role of Telomeres Shortening in Atherogenesis: An Overview. Cells 2021; 10:395. [PMID: 33671887 PMCID: PMC7918954 DOI: 10.3390/cells10020395] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Revised: 02/07/2021] [Accepted: 02/13/2021] [Indexed: 02/07/2023] Open
Abstract
It is known that the shortening of the telomeres leads to cell senescence, accompanied by acquiring of pro-inflammatory phenotype. The expression of telomerase can elongate telomeres and resist the onset of senescence. The initiation of atherosclerosis is believed to be associated with local senescence of the endothelial cells of the arteries in places with either low or multidirectional oscillatory wall shear stress. The process of regeneration of the artery surface that has begun does not lead to success for several reasons. Atherosclerotic plaques are formed, which, when developed, lead to fatal consequences, which are the leading causes of death in the modern world. The pronounced age dependence of the manifestations of atherosclerosis pushes scientists to try to link the development of atherosclerosis with telomere length. The study of the role of telomere shortening in atherosclerosis is mainly limited to measuring the telomeres of blood cells, and only in rare cases (surgery or post-mortem examination) are the telomeres of local cells available for measurement. The review discusses the basic issues of cellular aging and the interpretation of telomere measurement data in atherosclerosis, as well as the prospects for the prevention and possible treatment of atherosclerosis.
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Affiliation(s)
- Yegor E. Yegorov
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow 119991, Russia;
| | - Anastasia V. Poznyak
- Institute for Atherosclerosis Research, Skolkovo Innovative Center, Moscow 121609, Russia
| | - Nikita G. Nikiforov
- Laboratory of Angiopathology, Institute of General Pathology and Pathophysiology, Moscow 125315, Russia;
- National Medical Research Center of Cardiology, Institute of Experimental Cardiology, Moscow 121552, Russia
- Institute of Gene Biology, Center of Collective Usage, Moscow 119334, Russia
| | - Antonina V. Starodubova
- Federal Research Centre for Nutrition, Biotechnology and Food Safety, Moscow 109240, Russia;
- Pirogov Russian National Research Medical University, Moscow 117997, Russia
| | - Alexander N. Orekhov
- Institute for Atherosclerosis Research, Skolkovo Innovative Center, Moscow 121609, Russia
- Laboratory of Angiopathology, Institute of General Pathology and Pathophysiology, Moscow 125315, Russia;
- Institute of Human Morphology, Moscow 117418, Russia
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14
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Huang J, Peng X, Dong K, Tao J, Yang Y. The Association between Antidiabetic Agents and Leukocyte Telomere Length in the Novel Classification of Type 2 Diabetes Mellitus. Gerontology 2020; 67:60-68. [PMID: 33321495 DOI: 10.1159/000511362] [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: 07/13/2020] [Accepted: 09/05/2020] [Indexed: 11/19/2022] Open
Abstract
AIMS This study aimed to explore the new role of telomere length (TL) in the novel classification of type 2 diabetes mellitus (T2DM) patients driven by cluster analysis. MATERIALS AND METHODS A total of 541 T2DM patients were divided into 4 subgroups by k-means analysis: mild obesity-related diabetes (MOD), severe insulin-deficient diabetes (SIDD), severe insulin-resistant diabetes (SIRD), and mild age-related diabetes (MARD). After patients with insufficient data were excluded, further analysis was conducted on 246 T2DM patients. The TL was detected using telomere restriction fragment, and the related diabetic indexes were also measured by clinical standard procedures. RESULTS The MARD group had significantly shorter TLs than the MOD and SIDD groups. Then, we subdivided all T2DM patients into the MARD and NONMARD groups, which included the MOD, SIDD, and SIRD groups. The TLs of the MARD group, associated with age, were discovered to be significantly shorter than those of the NONMARD group (p = 0.0012), and this difference in TL disappeared after metformin (p = 0.880) and acarbose treatment (p = 0.058). The linear analysis showed that metformin can more obviously reduce telomere shortening in the MARD group (r = 0.030, 95% CI 0.010-0.051, p = 0.004), and acarbose can more apparently promote telomere attrition in the SIRD group (r = -0.069, 95% CI -0.100 to -0.039, p< 0.001) compared with other T2DM patients after adjusting for age and gender. CONCLUSIONS The MARD group was found to have shorter TLs and benefit more from the antiaging effect of metformin than other T2DM. Shorter TLs were observed in the SIRD group after acarbose use.
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Affiliation(s)
- Jiaojiao Huang
- Department of Endocrinology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xuemin Peng
- Department of Endocrinology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Kun Dong
- Department of Endocrinology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jing Tao
- Department of Endocrinology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yan Yang
- Department of Endocrinology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China,
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15
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Guterres AN, Villanueva J. Targeting telomerase for cancer therapy. Oncogene 2020; 39:5811-5824. [PMID: 32733068 PMCID: PMC7678952 DOI: 10.1038/s41388-020-01405-w] [Citation(s) in RCA: 91] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 07/02/2020] [Accepted: 07/23/2020] [Indexed: 12/20/2022]
Abstract
Telomere maintenance via telomerase reactivation is a nearly universal hallmark of cancer cells which enables replicative immortality. In contrast, telomerase activity is silenced in most adult somatic cells. Thus, telomerase represents an attractive target for highly selective cancer therapeutics. However, development of telomerase inhibitors has been challenging and thus far there are no clinically approved strategies exploiting this cancer target. The discovery of prevalent mutations in the TERT promoter region in many cancers and recent advances in telomerase biology has led to a renewed interest in targeting this enzyme. Here we discuss recent efforts targeting telomerase, including immunotherapies and direct telomerase inhibitors, as well as emerging approaches such as targeting TERT gene expression driven by TERT promoter mutations. We also address some of the challenges to telomerase-directed therapies including potential therapeutic resistance and considerations for future therapeutic applications and translation into the clinical setting. Although much work remains to be done, effective strategies targeting telomerase will have a transformative impact for cancer therapy and the prospect of clinically effective drugs is boosted by recent advances in structural models of human telomerase.
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Affiliation(s)
- Adam N Guterres
- Molecular and Cellular Oncogenesis Program, The Wistar Institute, Philadelphia, PA, USA
| | - Jessie Villanueva
- Molecular and Cellular Oncogenesis Program, The Wistar Institute, Philadelphia, PA, USA.
- Melanoma Research Center, The Wistar Institute, Philadelphia, PA, USA.
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16
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Telomerase Biogenesis and Activities from the Perspective of Its Direct Interacting Partners. Cancers (Basel) 2020; 12:cancers12061679. [PMID: 32599885 PMCID: PMC7352425 DOI: 10.3390/cancers12061679] [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: 06/01/2020] [Revised: 06/20/2020] [Accepted: 06/22/2020] [Indexed: 12/15/2022] Open
Abstract
Telomerase reverse transcriptase (TERT)—the catalytic subunit of telomerase—is reactivated in up to 90% of all human cancers. TERT is observed in heterogenous populations of protein complexes, which are dynamically regulated in a cell type- and cell cycle-specific manner. Over the past two decades, in vitro protein–protein interaction detection methods have discovered a number of endogenous TERT binding partners in human cells that are responsible for the biogenesis and functionalization of the telomerase holoenzyme, including the processes of TERT trafficking between subcellular compartments, assembly into telomerase, and catalytic action at telomeres. Additionally, TERT have been found to interact with protein species with no known telomeric functions, suggesting that these complexes may contribute to non-canonical activities of TERT. Here, we survey TERT direct binding partners and discuss their contributions to TERT biogenesis and functions. The goal is to review the comprehensive spectrum of TERT pro-malignant activities, both telomeric and non-telomeric, which may explain the prevalence of its upregulation in cancer.
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17
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Comparative Cytogenetic Mapping and Telomere Analysis Provide Evolutionary Predictions for Devil Facial Tumour 2. Genes (Basel) 2020; 11:genes11050480. [PMID: 32354058 PMCID: PMC7290341 DOI: 10.3390/genes11050480] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 04/06/2020] [Accepted: 04/26/2020] [Indexed: 01/20/2023] Open
Abstract
The emergence of a second transmissible tumour in the Tasmanian devil population, devil facial tumour 2 (DFT2), has prompted questions on the origin and evolution of these transmissible tumours. We used a combination of cytogenetic mapping and telomere length measurements to predict the evolutionary trajectory of chromosome rearrangements in DFT2. Gene mapping by fluorescence in situ hybridization (FISH) provided insight into the chromosome rearrangements in DFT2 and identified the evolution of two distinct DFT2 lineages. A comparison of devil facial tumour 1 (DFT1) and DFT2 chromosome rearrangements indicated that both started with the fusion of a chromosome, with potentially critically short telomeres, to chromosome 1 to form dicentric chromosomes. In DFT1, the dicentric chromosome resulted in breakage–fusion–bridge cycles leading to highly rearranged chromosomes. In contrast, the silencing of a centromere on the dicentric chromosome in DFT2 stabilized the chromosome, resulting in a less rearranged karyotype than DFT1. DFT2 retains a bimodal distribution of telomere length dimorphism observed on Tasmanian devil chromosomes, a feature lost in DFT1. Using long term cell culture, we observed homogenization of telomere length over time. We predict a similar homogenization of telomere lengths occurred in DFT1, and that DFT2 is unlikely to undergo further substantial rearrangements due to maintained telomere length.
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18
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Liu J, Ge Y, Wu S, Ma D, Xu W, Zhang Y, Yang Y. Association between antidiabetic agents use and leukocyte telomere shortening rates in patients with type 2 diabetes. Aging (Albany NY) 2020; 11:741-755. [PMID: 30694216 PMCID: PMC6366988 DOI: 10.18632/aging.101781] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Accepted: 01/15/2019] [Indexed: 12/25/2022]
Abstract
Telomere length and telomere shortening rate (TSR) are accepted indicators of aging in cross-sectional population studies. This study aimed to investigate the potential influence of common antidiabetic agents on telomere length and TSR in patients with type 2 diabetes mellitus (T2DM). Leukocyte telomere length was measured through terminal restriction fragment analysis, and TSR was calculated in 388 T2DM patients. Depending on whether or not they received antidiabetic medication, patients were first divided into a treatment group and a nontreatment group. Treated patients were further subdivided into an acarbose-free group (patients taking antidiabetic agents without acarbose) and an acarbose group (patients using acarbose for more than 3 months). Results showed that untreated patients had higher TSRs than patients on antidiabetic drugs. Interestingly, patients in the acarbose group had significantly higher TSRs than patients in the acarbose-free group. Compared to the nontreatment group, the acarbose group showed better glycemic control of HbA1c, but the TSR was also higher. Our results suggest that antidiabetic treatments without acarbose can slow aging. By contrast, acarbose may accelerate biological aging in patients with T2DM, independently of glycemic control.
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Affiliation(s)
- Juanhong Liu
- Department of Endocrinology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Yuanlong Ge
- Key Laboratory of Gene Engineering of the Ministry of Education, School of Life Sciences, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Shu Wu
- Key Laboratory of Gene Engineering of the Ministry of Education, School of Life Sciences, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Delin Ma
- Department of Endocrinology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Weijie Xu
- Department of Endocrinology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Ye Zhang
- Department of Endocrinology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Yan Yang
- Department of Endocrinology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
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19
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Toubiana S, Gagliardi M, Papa M, Manco R, Tzukerman M, Matarazzo MR, Selig S. Persistent epigenetic memory impedes rescue of the telomeric phenotype in human ICF iPSCs following DNMT3B correction. eLife 2019; 8:e47859. [PMID: 31738163 PMCID: PMC6897513 DOI: 10.7554/elife.47859] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Accepted: 11/17/2019] [Indexed: 12/15/2022] Open
Abstract
DNA methyltransferase 3B (DNMT3B) is the major DNMT that methylates mammalian genomes during early development. Mutations in human DNMT3B disrupt genome-wide DNA methylation patterns and result in ICF syndrome type 1 (ICF1). To study whether normal DNA methylation patterns may be restored in ICF1 cells, we corrected DNMT3B mutations in induced pluripotent stem cells from ICF1 patients. Focusing on repetitive regions, we show that in contrast to pericentromeric repeats, which reacquire normal methylation, the majority of subtelomeres acquire only partial DNA methylation and, accordingly, the ICF1 telomeric phenotype persists. Subtelomeres resistant to de novo methylation were characterized by abnormally high H3K4 trimethylation (H3K4me3), and short-term reduction of H3K4me3 by pharmacological intervention partially restored subtelomeric DNA methylation. These findings demonstrate that the abnormal epigenetic landscape established in ICF1 cells restricts the recruitment of DNMT3B, and suggest that rescue of epigenetic diseases with genome-wide disruptions will demand further manipulation beyond mutation correction.
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Affiliation(s)
- Shir Toubiana
- Molecular Medicine LaboratoryRappaport Faculty of Medicine, TechnionHaifaIsrael
- Rambam Health Care CampusHaifaIsrael
| | | | | | - Roberta Manco
- Institute of Genetics and Biophysics, ABT CNRNaplesItaly
| | - Maty Tzukerman
- Molecular Medicine LaboratoryRappaport Faculty of Medicine, TechnionHaifaIsrael
- Rambam Health Care CampusHaifaIsrael
| | | | - Sara Selig
- Molecular Medicine LaboratoryRappaport Faculty of Medicine, TechnionHaifaIsrael
- Rambam Health Care CampusHaifaIsrael
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20
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Vaijanathappa J, Puttaswamygowda J, Bevanhalli R, Dixit S, Prabhakaran P. Molecular docking, antiproliferative and anticonvulsant activities of swertiamarin isolated from Enicostemma axillare. Bioorg Chem 2019; 94:103428. [PMID: 31740047 DOI: 10.1016/j.bioorg.2019.103428] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2019] [Revised: 10/02/2019] [Accepted: 11/06/2019] [Indexed: 12/18/2022]
Abstract
Present study aimed for molecular docking, antiproliferative and anticonvulsant activities of swertiamarin isolated from the successive methanol extract of Enicostemma axillare. Molecular docking of swertiamarin on telomerase targets (PDB ID: 5UGW, 3DU6 and 4ERD), followed by antiproliferative activity on HEp2 and HT-29 cells by MTT and SRB assays. Also tested for anticonvulsant activity by pentylenetetrazole (PTZ, 80 mg/kg bw) induced convulsant. Molecular docking study predicted good total score of the swertiamarin with the selected targets. Swertiamarin possesses antiproliferative activity on HEp-2 and HT-29 cells with lower CTC50 values. It also served as significant anticonvulsant agent with prolonged onset and reduced duration of the seizures. These results confirm that swertiamarin exhibited potential antiproliferative and anticonvulsant activities.
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Affiliation(s)
- Jaishree Vaijanathappa
- Department of Pharmaceutical Chemistry, JSS College of Pharmacy, Mysuru 570015, Karnataka, India.
| | - Jamuna Puttaswamygowda
- Department of Pharmaceutical Chemistry, Sri Adichunchanagiri College of Pharmacy, B. G. Nagar - 571448, Mandya District, Karnataka, India
| | - Ramesh Bevanhalli
- Department of Pharmaceutical Chemistry, Sri Adichunchanagiri College of Pharmacy, B. G. Nagar - 571448, Mandya District, Karnataka, India
| | - Sheshagiri Dixit
- Department of Pharmaceutical Chemistry, JSS College of Pharmacy, Mysuru 570015, Karnataka, India
| | - Prabitha Prabhakaran
- Department of Pharmaceutical Chemistry, JSS College of Pharmacy, Mysuru 570015, Karnataka, India
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21
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Sayed ME, Cheng A, Yadav GP, Ludlow AT, Shay JW, Wright WE, Jiang QX. Catalysis-dependent inactivation of human telomerase and its reactivation by intracellular telomerase-activating factors (iTAFs). J Biol Chem 2019; 294:11579-11596. [PMID: 31186347 DOI: 10.1074/jbc.ra118.007234] [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: 12/19/2018] [Revised: 06/04/2019] [Indexed: 12/17/2022] Open
Abstract
Human telomerase maintains genome stability by adding telomeric repeats to the ends of linear chromosomes. Although previous studies have revealed profound insights into telomerase functions, the low cellular abundance of functional telomerase and the difficulties in quantifying its activity leave its thermodynamic and kinetic properties only partially characterized. Employing a stable cell line overexpressing both the human telomerase RNA component and the N-terminally biotinylated human telomerase reverse transcriptase and using a newly developed method to count individual extension products, we demonstrate here that human telomerase holoenzymes contain fast- and slow-acting catalytic sites. Surprisingly, both active sites became inactive after two consecutive rounds of catalysis, named single-run catalysis. The fast active sites turned off ∼40-fold quicker than the slow ones and exhibited higher affinities to DNA substrates. In a dimeric enzyme, the two active sites work in tandem, with the faster site functioning before the slower one, and in the monomeric enzyme, the active sites also perform single-run catalysis. Interestingly, inactive enzymes could be reactivated by intracellular telomerase-activating factors (iTAFs) from multiple cell types. We conclude that the single-run catalysis and the iTAF-triggered reactivation serve as an unprecedented control circuit for dynamic regulation of telomerase. They endow native telomerase holoenzymes with the ability to match their total number of active sites to the number of telomeres they extend. We propose that the exquisite kinetic control of telomerase activity may play important roles in both cell division and cell aging.
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Affiliation(s)
- Mohammed E Sayed
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390.,School of Kinesiology Integrative Molecular Genetics Lab, University of Michigan, Ann Arbor, Michigan 48109
| | - Ao Cheng
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390.,Department of Diagnostic and Biological Sciences, University of Minnesota, Minneapolis, Minnesota 55455
| | - Gaya P Yadav
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390.,Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida 32611
| | - Andrew T Ludlow
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390.,School of Kinesiology Integrative Molecular Genetics Lab, University of Michigan, Ann Arbor, Michigan 48109
| | - Jerry W Shay
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Woodring E Wright
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Qiu-Xing Jiang
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390 .,Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida 32611
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22
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Liu Y, Liu F, Cao Y, Xu H, Wu Y, Wu S, Liu D, Zhao Y, Songyang Z, Ma W. Shwachman-Diamond Syndrome Protein SBDS Maintains Human Telomeres by Regulating Telomerase Recruitment. Cell Rep 2019; 22:1849-1860. [PMID: 29444436 DOI: 10.1016/j.celrep.2018.01.057] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Revised: 12/20/2017] [Accepted: 01/19/2018] [Indexed: 01/15/2023] Open
Abstract
Shwachman-Diamond syndrome (SDS) is a rare pediatric disease characterized by various systemic disorders, including hematopoietic dysfunction. The mutation of Shwachman-Bodian-Diamond syndrome (SBDS) gene has been proposed to be a major causative reason for SDS. Although SBDS patients were reported to have shorter telomere length in granulocytes, the underlying mechanism is still unclear. Here we provide data to elucidate the role of SBDS in telomere protection. We demonstrate that SBDS deficiency leads to telomere shortening. We found that overexpression of disease-associated SBDS mutants or knockdown of SBDS hampered the recruitment of telomerase onto telomeres, while the overall reverse transcriptase activity of telomerase remained unaffected. Moreover, we show that SBDS could specifically bind to TPP1 during the S phase of cell cycle, likely functioning as a stabilizer for TPP1-telomerase interaction. Our findings suggest that SBDS is a telomere-protecting protein that participates in regulating telomerase recruitment.
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Affiliation(s)
- Yi Liu
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Oncology in South China, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Feng Liu
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Oncology in South China, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China.
| | - Yizhao Cao
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Oncology in South China, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Huimin Xu
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Oncology in South China, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Yangxiu Wu
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Oncology in South China, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Su Wu
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Oncology in South China, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Dan Liu
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Yong Zhao
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Oncology in South China, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Zhou Songyang
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Oncology in South China, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China; Collaborative Innovation Center for Cancer Medicine, Institute of Healthy Aging Research, Sun Yat-sen University, Guangzhou 510006, China; Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.
| | - Wenbin Ma
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Oncology in South China, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China; Collaborative Innovation Center for Cancer Medicine, Institute of Healthy Aging Research, Sun Yat-sen University, Guangzhou 510006, China.
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23
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Abstract
Telomeres are specialised structures at the end of linear chromosomes. They consist of tandem repeats of the hexanucleotide sequence TTAGGG, as well as a protein complex called shelterin. Together, they form a protective loop structure against chromosome fusion and degradation. Shortening or damage to telomeres and opening of the loop induce an uncapped state that triggers a DNA damage response resulting in senescence or apoptosis.Average telomere length, usually measured in human blood lymphocytes, was thought to be a biomarker for ageing, survival and mortality. However, it becomes obvious that regulation of telomere length is very complex and involves multiple processes. For example, the "end replication problem" during DNA replication as well as oxidative stress are responsible for the shortening of telomeres. In contrast, telomerase activity can potentially counteract telomere shortening when it is able to access and interact with telomeres. However, while highly active during development and in cancer cells, the enzyme is down-regulated in most human somatic cells with a few exceptions such as human lymphocytes. In addition, telomeres can be transcribed, and the transcription products called TERRA are involved in telomere length regulation.Thus, telomere length and their integrity are regulated at many different levels, and we only start to understand this process under conditions of increased oxidative stress, inflammation and during diseases as well as the ageing process.This chapter aims to describe our current state of knowledge on telomeres and telomerase and their regulation in order to better understand their role for the ageing process.
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24
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Mensà E, Latini S, Ramini D, Storci G, Bonafè M, Olivieri F. The telomere world and aging: Analytical challenges and future perspectives. Ageing Res Rev 2019; 50:27-42. [PMID: 30615937 DOI: 10.1016/j.arr.2019.01.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 11/15/2018] [Accepted: 01/03/2019] [Indexed: 12/12/2022]
Abstract
Telomeres, the terminal nucleoprotein structures of eukaryotic chromosomes, play pleiotropic functions in cellular and organismal aging. Telomere length (TL) varies throughout life due to the influence of genetic factors and to a complex balancing between "shortening" and "elongation" signals. Telomerase, the only enzyme that can elongate a telomeric DNA chain, and telomeric repeat-containing RNA (TERRA), a long non-coding RNA involved in looping maintenance, play key roles in TL during life. Despite recent advances in the knowledge of TL, TERRA and telomerase activity (TA) biology and their measurement techniques, the experimental and theoretical issues involved raise a number of problems that should carefully be considered by researchers approaching the "telomere world". The increasing use of such parameters - hailed as promising clinically relevant biomarkers - has failed to be paralleled by the development of automated and standardized measurement technology. Consequently, associating given TL values to specific pathological conditions involves on the one hand technological issues and on the other clinical-biological issues related to the planning of clinically relevant association studies. Addressing these issues would help avoid major biases in association studies involving TL and a number of outcomes, especially those focusing on psychological and bio-behavioral variables. The main challenge in telomere research is the development of accurate and reliable measurement methods to achieve simple and sensitive TL, TERRA, and TA detection. The discovery of the localization of telomeres and TERRA in cellular and extracellular compartments had added an additional layer of complexity to the measurement of these age-related biomarkers. Since combined analysis of TL, TERRA and TA may well provide more exhaustive clinical information than a single parameter, we feel it is important for researchers in the various fields to become familiar with their most common measurement techniques and to be aware of the respective merits and drawbacks of these approaches.
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Affiliation(s)
- Emanuela Mensà
- Department of Clinical and Molecular Sciences, DISCLIMO, Università Politecnica delle Marche, Ancona, Italy
| | - Silvia Latini
- Department of Clinical and Molecular Sciences, DISCLIMO, Università Politecnica delle Marche, Ancona, Italy
| | - Deborah Ramini
- Department of Clinical and Molecular Sciences, DISCLIMO, Università Politecnica delle Marche, Ancona, Italy
| | - Gianluca Storci
- Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, Bologna, Italy; Interdepartmental Centre "L. Galvani" (CIG), University of Bologna, Bologna, Italy
| | - Massimiliano Bonafè
- Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, Bologna, Italy; Interdepartmental Centre "L. Galvani" (CIG), University of Bologna, Bologna, Italy; Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRST), IRCCS, Biosciences Laboratory, Meldola, Italy
| | - Fabiola Olivieri
- Department of Clinical and Molecular Sciences, DISCLIMO, Università Politecnica delle Marche, Ancona, Italy; Center of Clinical Pathology and Innovative Therapy, IRCCS INRCA, Ancona, Italy.
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25
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Zhang T, Zhang Z, Shengzhao G, Li X, Liu H, Zhao Y. Strand break-induced replication fork collapse leads to C-circles, C-overhangs and telomeric recombination. PLoS Genet 2019; 15:e1007925. [PMID: 30716077 PMCID: PMC6382176 DOI: 10.1371/journal.pgen.1007925] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 02/20/2019] [Accepted: 01/01/2019] [Indexed: 12/16/2022] Open
Abstract
Telomerase-independent ALT (alternative lengthening of telomeres) cells are characterized by high frequency of telomeric homologous recombination (HR), C-rich extrachromosomal circles (C-circles) and C-rich terminal 5' overhangs (C-overhangs). However, underlying mechanism is poorly understood. Here, we show that both C-circle and C-overhang form when replication fork collapse is induced by strand break at telomeres. We find that endogenous DNA break predominantly occur on C-rich strand of telomeres in ALT cells, resulting in high frequency of replication fork collapse. While collapsed forks could be rescued by replication fork regression leading to telomeric homologous recombination, those unresolved are converted to C-circles and C-overhang at lagging and leading synthesized strand, respectively. Meanwhile, multiple hallmarks of ALT are provoked, suggesting that strand break-induced replication stress underlies ALT. These findings provide a molecular basis underlying telomeric HR and biogenesis of C-circle and C-overhang, thus implicating the specific mechanism to resolve strand break-induced replication defect at telomeres in ALT cells. 10 to 15% human cancers utilize telomerase-independent alternative lengthening of telomeres (ALT) to maintain their telomere length. Unexpectedly, we find that endogenous C-strand breaks predominantly exist in telomeres of ALT cells, which induce high frequency of replication fork collapse. While collapsed fork triggers fork regression machinery to restart the replication, leading to telomeric homologous recombination; those unresolved are converted to C-circle and C-overhang. These findings suggest that the formation of C-circle and C-overhang represents a unique manner for ALT cells to prevent chromosome instability induced by replication defect at telomeres. Moreover, multiple hallmarks of ALT are provoked during this process, demonstrating that DNA strand break at telomeres underlies ALT mechanism.
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Affiliation(s)
- Tianpeng Zhang
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, P. R. China
| | - Zepeng Zhang
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, P. R. China
| | - Gong Shengzhao
- School of Chemical Engineering and Technology, Guangdong Engineering Technical Research Center for Green Household Chemicals, Guangdong Industry Technical College, Guangzhou, P.R.China
| | - Xiaocui Li
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, P. R. China
| | - Haiying Liu
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, P. R. China
| | - Yong Zhao
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, P. R. China
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, P. R. China
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26
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Okamoto K, Seimiya H. Revisiting Telomere Shortening in Cancer. Cells 2019; 8:cells8020107. [PMID: 30709063 PMCID: PMC6406355 DOI: 10.3390/cells8020107] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Revised: 01/28/2019] [Accepted: 01/28/2019] [Indexed: 12/21/2022] Open
Abstract
Telomeres, the protective structures of chromosome ends are gradually shortened by each cell division, eventually leading to senescence or apoptosis. Cancer cells maintain the telomere length for unlimited growth by telomerase reactivation or a recombination-based mechanism. Recent genome-wide analyses have unveiled genetic and epigenetic alterations of the telomere maintenance machinery in cancer. While telomerase inhibition reveals that longer telomeres are more advantageous for cell survival, cancer cells often have paradoxically shorter telomeres compared with those found in the normal tissues. In this review, we summarize the latest knowledge about telomere length alterations in cancer and revisit its rationality. Finally, we discuss the potential utility of telomere length as a prognostic biomarker.
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Affiliation(s)
- Keiji Okamoto
- Division of Molecular Biotherapy, Cancer Chemotherapy Center, Japanese Foundation for Cancer Research, Koto-ku, Tokyo 135-8550, Japan.
| | - Hiroyuki Seimiya
- Division of Molecular Biotherapy, Cancer Chemotherapy Center, Japanese Foundation for Cancer Research, Koto-ku, Tokyo 135-8550, Japan.
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27
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Liu H, Xie Y, Zhang Z, Mao P, Liu J, Ma W, Zhao Y. Telomeric Recombination Induced by DNA Damage Results in Telomere Extension and Length Heterogeneity. Neoplasia 2018; 20:905-916. [PMID: 30118998 PMCID: PMC6097467 DOI: 10.1016/j.neo.2018.07.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 07/20/2018] [Accepted: 07/24/2018] [Indexed: 12/11/2022] Open
Abstract
About 15% of human cancers counteract telomere loss by alternative lengthening of telomeres (ALT), which is attributed to homologous recombination (HR)–mediated events. But how telomeric HR leads to length elongation is poorly understood. Here, we explore telomere clustering and telomeric HR induced by double-stranded breaks (DSBs). We show that telomere clustering could occur at G1 and S phase of cell cycle and that three types of telomeric HR occur based on the manner of telomeric DNA exchange: equivalent telomeric sister chromatin exchange (T-SCE), inequivalent T-SCE, and No-SCE. While inequivalent T-SCE increases telomere length heterogeneity with no net gain of telomere length, No-SCE, which is presumably induced by interchromatid HR and/or break-induced replication, results in telomere elongation. Accordingly, cells subjected to long-term telomeric DSBs display increased heterogeneity of length and longer telomeres. We also demonstrate that DSBs-induced telomere elongation is telomerase independent. Moreover, telomeric recombination induced by DSBs is associated with formation of ALT-associated PML body and C-circle. Thus, DNA damage triggers recombination mediated elongation, leading to the induction of multiple ALT phenotypes.
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Affiliation(s)
- Haiying Liu
- MOE Key Laboratory of Gene Function and Regulation, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, P. R. China; Collaborative Innovation Center of High Performance Computing, National University of Defense Technology, Changsha 410073, P. R. China
| | - Yujie Xie
- MOE Key Laboratory of Gene Function and Regulation, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, P. R. China; Collaborative Innovation Center of High Performance Computing, National University of Defense Technology, Changsha 410073, P. R. China
| | - Zepeng Zhang
- MOE Key Laboratory of Gene Function and Regulation, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, P. R. China; Collaborative Innovation Center of High Performance Computing, National University of Defense Technology, Changsha 410073, P. R. China
| | - Pingsu Mao
- MOE Key Laboratory of Gene Function and Regulation, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, P. R. China; Collaborative Innovation Center of High Performance Computing, National University of Defense Technology, Changsha 410073, P. R. China
| | - Jingfan Liu
- MOE Key Laboratory of Gene Function and Regulation, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, P. R. China; Collaborative Innovation Center of High Performance Computing, National University of Defense Technology, Changsha 410073, P. R. China
| | - Wenbin Ma
- MOE Key Laboratory of Gene Function and Regulation, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, P. R. China
| | - Yong Zhao
- MOE Key Laboratory of Gene Function and Regulation, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, P. R. China; Collaborative Innovation Center of High Performance Computing, National University of Defense Technology, Changsha 410073, P. R. China.
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28
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Toubiana S, Selig S. DNA:RNA hybrids at telomeres - when it is better to be out of the (R) loop. FEBS J 2018; 285:2552-2566. [PMID: 29637701 DOI: 10.1111/febs.14464] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Revised: 03/11/2018] [Accepted: 04/03/2018] [Indexed: 01/31/2023]
Abstract
R-loops (RLs) are three-stranded nucleic acid structures that contain a DNA:RNA hybrid and a displaced DNA strand. Genomic regions with GC skew and a G-rich transcript are particularly prone to form RLs. RLs play important physiological roles in cells; however, when present at abnormally high levels, they may threaten genome stability. The perfect GC skew of telomeric repeats and the discovery of telomeric repeat-containing RNA (TERRA), a long noncoding transcript that consists of the G-rich telomeric sequence, make telomeric sequences the perfect candidates for generating RLs. Indeed, in the past 5 years, telomere R-loops (TRLs) have been demonstrated in Saccharomyces cerevisiae, Trypanosoma brucei, and human cells. The presence of TRLs in normal human cells that transcribe low levels of TERRA, suggests a physiological role for these nucleic structures in telomere maintenance. Abnormally enhanced TERRA transcription, as found in several human pathological conditions, leads to high TRL levels and various cellular outcomes, depending on the recombinogenic capabilities of the cells. Study of TRLs in various organisms highlights the necessity for tight regulation of these structures, which can switch from beneficial to detrimental under different conditions. Here, we review the current state of knowledge on TRLs, describe several means by which TRLs are regulated, and discuss how findings from yeast are relevant to human pathological scenarios in which TRLs are deregulated.
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Affiliation(s)
- Shir Toubiana
- Molecular Medicine Laboratory, Rappaport Faculty of Medicine, Rambam Health Care Campus, Technion, Haifa, Israel
| | - Sara Selig
- Molecular Medicine Laboratory, Rappaport Faculty of Medicine, Rambam Health Care Campus, Technion, Haifa, Israel
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29
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Song S, Johnson FB. Epigenetic Mechanisms Impacting Aging: A Focus on Histone Levels and Telomeres. Genes (Basel) 2018; 9:genes9040201. [PMID: 29642537 PMCID: PMC5924543 DOI: 10.3390/genes9040201] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2018] [Revised: 03/27/2018] [Accepted: 03/29/2018] [Indexed: 12/13/2022] Open
Abstract
Aging and age-related diseases pose some of the most significant and difficult challenges to modern society as well as to the scientific and medical communities. Biological aging is a complex, and, under normal circumstances, seemingly irreversible collection of processes that involves numerous underlying mechanisms. Among these, chromatin-based processes have emerged as major regulators of cellular and organismal aging. These include DNA methylation, histone modifications, nucleosome positioning, and telomere regulation, including how these are influenced by environmental factors such as diet. Here we focus on two interconnected categories of chromatin-based mechanisms impacting aging: those involving changes in the levels of histones or in the functions of telomeres.
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Affiliation(s)
- Shufei Song
- Biochemistry and Molecular Biophysics Graduate Group, Biomedical Graduate Studies, University of Pennsylvania, Philadelphia, PA 19104, USA.
- Department of Pathology and Laboratory Medicine, and Institute on Aging, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
| | - F Brad Johnson
- Department of Pathology and Laboratory Medicine, and Institute on Aging, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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30
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Lin S, Wei J, Wunderlich M, Chou FS, Mulloy JC. Immortalization of human AE pre-leukemia cells by hTERT allows leukemic transformation. Oncotarget 2018; 7:55939-55950. [PMID: 27509060 PMCID: PMC5302887 DOI: 10.18632/oncotarget.11093] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Accepted: 06/13/2016] [Indexed: 01/21/2023] Open
Abstract
Human CD34+ hematopoietic stem and progenitor cells (HSPC) expressing fusion protein AML1-ETO (AE), generated by the t(8;21)(q22;q22) rearrangement, manifest enhanced self-renewal and dysregulated differentiation without leukemic transformation, representing a pre-leukemia stage. Enabling replicative immortalization via telomerase reactivation is a crucial step in cancer development. However, AE expression alone is not sufficient to maintain high telomerase activity to immortalize human HSPC cells, which may hamper transformation. Here, we investigated the cooperativity of telomerase reverse transcriptase (hTERT), the catalytic subunit of telomerase, and AE in disease progression. Enforced expression of hTERT immortalized human AE pre-leukemia cells in a telomere-lengthening independent manner, and improved the pre-leukemia stem cell function by enhancing cell proliferation and survival. AE-hTERT cells retained cytokine dependency and multi-lineage differentiation potential similar to parental AE clones. Over the short-term, AE-hTERT cells did not show features of stepwise transformation, with no leukemogenecity evident upon initial injection into immunodeficient mice. Strikingly, after extended culture, we observed full transformation of one AE-hTERT clone, which recapitulated the disease evolution process in patients and emphasizes the importance of acquiring cooperating mutations in t(8;21) AML leukemogenesis. In summary, achieving unlimited proliferative potential via hTERT activation, and thereby allowing for acquisition of additional mutations, is a critical link for transition from pre-leukemia to overt disease in human cells. AE-hTERT cells represent a tractable model to study cooperating genetic lesions important for t(8;21) AML disease progression.
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Affiliation(s)
- Shan Lin
- Cancer and Blood Disease Institute, Cincinnati Children's Hospital Research Center, Cincinnati, OH, USA
| | - Junping Wei
- Cancer and Blood Disease Institute, Cincinnati Children's Hospital Research Center, Cincinnati, OH, USA
| | - Mark Wunderlich
- Cancer and Blood Disease Institute, Cincinnati Children's Hospital Research Center, Cincinnati, OH, USA
| | - Fu-Sheng Chou
- Cancer and Blood Disease Institute, Cincinnati Children's Hospital Research Center, Cincinnati, OH, USA
| | - James C Mulloy
- Cancer and Blood Disease Institute, Cincinnati Children's Hospital Research Center, Cincinnati, OH, USA
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31
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Sagie S, Edni O, Weinberg J, Toubiana S, Kozlovski T, Frostig T, Katzin N, Bar-Am I, Selig S. Non-random length distribution of individual telomeres in immunodeficiency, centromeric instability and facial anomalies syndrome, type I. Hum Mol Genet 2017; 26:4244-4256. [PMID: 28973513 DOI: 10.1093/hmg/ddx313] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 08/03/2017] [Indexed: 12/30/2022] Open
Abstract
Mutations in the de novo DNA methyltransferase DNMT3B lead to Immunodeficiency, Centromeric Instability and Facial anomalies (ICF) syndrome, type I. This syndrome is characterized, among other hypomethylated genomic loci, by severe subtelomeric hypomethylation that is associated with abnormally short telomere length. While it was demonstrated that the mean telomere length is significantly shorter in ICF type I cells, it is unknown whether all telomeres are equally vulnerable to shortening. To study this question we determined by combined telomere-FISH and spectral karyotyping the relative length of each individual telomere in lymphoblastoid cell lines (LCLs) generated from multiple ICF syndrome patients and control individuals. Here we confirm the short telomere lengths, and demonstrate that telomere length variance in the ICF patient group is much larger than in the control group, suggesting that not all telomeres shorten in a uniform manner. We identified a subgroup of telomeres whose relatively short lengths can distinguish with a high degree of certainty between a control and an ICF metaphase, proposing that in ICF syndrome cells, certain individual telomeres are consistently at greater risk to shorten than others. The majority of these telomeres display high sequence identity at the distal 2 kb of their subtelomeres, suggesting that the attenuation in DNMT3B methylation capacity affects individual telomeres to different degrees based, at least in part, on the adjacent subtelomeric sequence composition.
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Affiliation(s)
- Shira Sagie
- Molecular Medicine Laboratory, Rambam Health Care Campus and Rappaport Faculty of Medicine, Technion, Haifa 31096, Israel
| | - Omer Edni
- Molecular Medicine Laboratory, Rambam Health Care Campus and Rappaport Faculty of Medicine, Technion, Haifa 31096, Israel
| | - Joseph Weinberg
- Molecular Medicine Laboratory, Rambam Health Care Campus and Rappaport Faculty of Medicine, Technion, Haifa 31096, Israel
| | - Shir Toubiana
- Molecular Medicine Laboratory, Rambam Health Care Campus and Rappaport Faculty of Medicine, Technion, Haifa 31096, Israel
| | - Tal Kozlovski
- Department of Statistics and Operations Research, The Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 39040, Israel
| | - Tzviel Frostig
- Department of Statistics and Operations Research, The Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 39040, Israel
| | - Nirit Katzin
- Applied Spectral Imaging Ltd., Yokneam 2069200, Israel
| | - Irit Bar-Am
- Applied Spectral Imaging Ltd., Yokneam 2069200, Israel
| | - Sara Selig
- Molecular Medicine Laboratory, Rambam Health Care Campus and Rappaport Faculty of Medicine, Technion, Haifa 31096, Israel
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32
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Kim H, Li F, He Q, Deng T, Xu J, Jin F, Coarfa C, Putluri N, Liu D, Songyang Z. Systematic analysis of human telomeric dysfunction using inducible telosome/shelterin CRISPR/Cas9 knockout cells. Cell Discov 2017; 3:17034. [PMID: 28955502 PMCID: PMC5613224 DOI: 10.1038/celldisc.2017.34] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 07/27/2017] [Indexed: 01/14/2023] Open
Abstract
CRISPR/Cas9 technology enables efficient loss-of-function analysis of human genes using
somatic cells. Studies of essential genes, however, require conditional knockout (KO)
cells. Here, we describe the generation of inducible CRISPR KO human cell lines for the
subunits of the telosome/shelterin complex, TRF1, TRF2, RAP1, TIN2, TPP1 and POT1, which
directly interact with telomeres or can bind to telomeres through association with other
subunits. Homozygous inactivation of several subunits is lethal in mice, and most
loss-of-function studies of human telomere regulators have relied on RNA
interference-mediated gene knockdown, which suffers its own limitations. Our inducible
CRISPR approach has allowed us to more expediently obtain large numbers of KO cells in
which essential telomere regulators have been inactivated for biochemical and molecular
studies. Our systematic analysis revealed functional differences between human and mouse
telomeric proteins in DNA damage responses, telomere length and metabolic control,
providing new insights into how human telomeres are maintained.
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Affiliation(s)
- Hyeung Kim
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Feng Li
- Key Laboratory of Gene Engineering of the Ministry of Education and State Key Laboratory for Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Quanyuan He
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Tingting Deng
- Key Laboratory of Gene Engineering of the Ministry of Education and State Key Laboratory for Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Jun Xu
- Cell-Based Assay Screening Service Core, Baylor College of Medicine, Houston, TX, USA
| | - Feng Jin
- Department of Molecular and Cellular Biology and Advanced Technology Core, Baylor College of Medicine, Houston, TX, USA
| | - Cristian Coarfa
- Department of Molecular and Cellular Biology and Advanced Technology Core, Baylor College of Medicine, Houston, TX, USA
| | - Nagireddy Putluri
- Department of Molecular and Cellular Biology and Advanced Technology Core, Baylor College of Medicine, Houston, TX, USA
| | - Dan Liu
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA.,Cell-Based Assay Screening Service Core, Baylor College of Medicine, Houston, TX, USA
| | - Zhou Songyang
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA.,Key Laboratory of Gene Engineering of the Ministry of Education and State Key Laboratory for Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
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33
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Xue HM, Liu QQ, Tian G, Quan LM, Zhao Y, Cheng G. Television Watching and Telomere Length Among Adults in Southwest China. Am J Public Health 2017; 107:1425-1432. [PMID: 28727527 DOI: 10.2105/ajph.2017.303879] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
OBJECTIVES To explore the independent associations of sedentary behavior and physical activity with telomere length among Chinese adults. METHODS Data on total time of sedentary behavior, screen-based sedentary behavior (including television watching and computer or phone use), moderate to vigorous physical activity, and dietary intake of 518 adults in Chengdu, Guizhou, and Xiamen in China (54.25% women) aged 20 to 70 years were obtained between 2013 and 2015 through questionnaires. Height, weight, and waist circumference were measured to calculate body mass index and percentage of body fat. Telomere length was measured through Southern blot technique. RESULTS Television watching was inversely related to adjusted telomere length (-71.75 base pair; SE = 34.40; P = .04). Furthermore, a similar trend between telomere length and television watching was found in the group aged 20 to 40 years after adjusting for all covariates. Adults aged 20 to 40 years in the highest tertile of daily time spent on watching television had 4.0% shorter telomere length than adults in the lowest tertile (P = .03). CONCLUSIONS Although the association is modest, television watching is inversely related to telomere length among Chinese adults, warranting further investigation in large prospective studies.
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Affiliation(s)
- Hong-Mei Xue
- Hong-mei Xue, Guo Tian, and Guo Cheng are with the Department of Nutrition, Food Safety and Toxicology, West China School of Public Health, Sichuan University, Chengdu, China. Qian-qian Liu and Yong Zhao are with the Key Laboratory of Gene Engineering, Ministry of Education, School of Life Sciences, Sun Yat-sen University, Guangzhou, China. Li-ming Quan is with the Office of Scientific Research Management, West China School of Public Health
| | - Qian-Qian Liu
- Hong-mei Xue, Guo Tian, and Guo Cheng are with the Department of Nutrition, Food Safety and Toxicology, West China School of Public Health, Sichuan University, Chengdu, China. Qian-qian Liu and Yong Zhao are with the Key Laboratory of Gene Engineering, Ministry of Education, School of Life Sciences, Sun Yat-sen University, Guangzhou, China. Li-ming Quan is with the Office of Scientific Research Management, West China School of Public Health
| | - Guo Tian
- Hong-mei Xue, Guo Tian, and Guo Cheng are with the Department of Nutrition, Food Safety and Toxicology, West China School of Public Health, Sichuan University, Chengdu, China. Qian-qian Liu and Yong Zhao are with the Key Laboratory of Gene Engineering, Ministry of Education, School of Life Sciences, Sun Yat-sen University, Guangzhou, China. Li-ming Quan is with the Office of Scientific Research Management, West China School of Public Health
| | - Li-Ming Quan
- Hong-mei Xue, Guo Tian, and Guo Cheng are with the Department of Nutrition, Food Safety and Toxicology, West China School of Public Health, Sichuan University, Chengdu, China. Qian-qian Liu and Yong Zhao are with the Key Laboratory of Gene Engineering, Ministry of Education, School of Life Sciences, Sun Yat-sen University, Guangzhou, China. Li-ming Quan is with the Office of Scientific Research Management, West China School of Public Health
| | - Yong Zhao
- Hong-mei Xue, Guo Tian, and Guo Cheng are with the Department of Nutrition, Food Safety and Toxicology, West China School of Public Health, Sichuan University, Chengdu, China. Qian-qian Liu and Yong Zhao are with the Key Laboratory of Gene Engineering, Ministry of Education, School of Life Sciences, Sun Yat-sen University, Guangzhou, China. Li-ming Quan is with the Office of Scientific Research Management, West China School of Public Health
| | - Guo Cheng
- Hong-mei Xue, Guo Tian, and Guo Cheng are with the Department of Nutrition, Food Safety and Toxicology, West China School of Public Health, Sichuan University, Chengdu, China. Qian-qian Liu and Yong Zhao are with the Key Laboratory of Gene Engineering, Ministry of Education, School of Life Sciences, Sun Yat-sen University, Guangzhou, China. Li-ming Quan is with the Office of Scientific Research Management, West China School of Public Health
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34
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Zhang T, Zhang Z, Li F, Hu Q, Liu H, Tang M, Ma W, Huang J, Songyang Z, Rong Y, Zhang S, Chen BP, Zhao Y. Looping-out mechanism for resolution of replicative stress at telomeres. EMBO Rep 2017; 18:1412-1428. [PMID: 28615293 DOI: 10.15252/embr.201643866] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Revised: 04/29/2017] [Accepted: 05/08/2017] [Indexed: 01/03/2023] Open
Abstract
Repetitive DNA is prone to replication fork stalling, which can lead to genome instability. Here, we find that replication fork stalling at telomeres leads to the formation of t-circle-tails, a new extrachromosomal structure that consists of circular telomeric DNA with a single-stranded tail. Structurally, the t-circle-tail resembles cyclized leading or lagging replication intermediates that are excised from the genome by topoisomerase II-mediated cleavage. We also show that the DNA damage repair machinery NHEJ is required for the formation of t-circle-tails and for the resolution of stalled replication forks, suggesting that NHEJ, which is normally constitutively suppressed at telomeres, is activated in the context of replication stress. Inhibition of NHEJ or knockout of DNA-PKcs impairs telomere replication, leading to multiple-telomere sites (MTS) and telomere shortening. Collectively, our results support a "looping-out" mechanism, in which the stalled replication fork is cut out and cyclized to form t-circle-tails, and broken DNA is religated. The telomere loss induced by replication stress may serve as a new factor that drives replicative senescence and cell aging.
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Affiliation(s)
- Tianpeng Zhang
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China.,Collaborative Innovation Center of High Performance Computing, National University of Defense Technology, Changsha, China
| | - Zepeng Zhang
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China.,Collaborative Innovation Center of High Performance Computing, National University of Defense Technology, Changsha, China
| | - Feng Li
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Qian Hu
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China.,Collaborative Innovation Center of High Performance Computing, National University of Defense Technology, Changsha, China
| | - Haiying Liu
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China.,Collaborative Innovation Center of High Performance Computing, National University of Defense Technology, Changsha, China
| | - Mengfan Tang
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Wenbin Ma
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Junjiu Huang
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Zhou Songyang
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Yikang Rong
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Shichuan Zhang
- Department of Radiation Oncology, Sichuan Cancer Hospital, Chengdu, China
| | - Benjamin Pc Chen
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Yong Zhao
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China .,Collaborative Innovation Center of High Performance Computing, National University of Defense Technology, Changsha, China
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Higher adherence to the 'vegetable-rich' dietary pattern is related to longer telomere length in women. Clin Nutr 2017; 37:1232-1237. [PMID: 28673689 DOI: 10.1016/j.clnu.2017.05.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Revised: 05/04/2017] [Accepted: 05/05/2017] [Indexed: 11/23/2022]
Abstract
BACKGROUND & AIMS Increasing evidence suggests a role of nutrition in aging process measured by telomere length (TL). However, data from Chinese are scarce. Moreover, the potential mechanism underlying diet and aging is not clear. Although inflammation has been hypothesized as one of the main factors, direct evidence is lacking. We examined whether dietary patterns were associated with TL in Chinese adults, with particular attention paid to body fat (excessive accumulation of body fat is a state of high-systematic oxidative stress and inflammation) and C-reactive protein (CRP, a marker of inflammation). METHODS Principal components analysis was used to identify dietary patterns from a 66-item food frequency questionnaire. TL was measured by Southern blots-based assay (Telomere restriction fragments, TRF). Data on sociodemographic characteristics, lifestyle behaviors, anthropometry and metabolism were collected. Multivariate linear regressions were performed in 553 Chinese adults (50.8% men) aged 25-65 years. RESULTS Four main dietary patterns were identified. After adjustment for potential confounders, only the 'vegetable-rich' pattern characterized by higher intake of fruits, whole grains, various vegetable groups, dairy products, nuts, eggs and tea, was positively related to TL in women (β = 160.81, P for trend <0.05). The strength of this relation was almost identical with further adjustment for body fat (β = 160.50, P for trend <0.05), but was attenuated slightly with additional adjustment for CRP (β = 152.02, P for trend <0.05). No significant relations were observed in men between dietary patterns and TL. CONCLUSIONS Chinese women with higher adherence to 'vegetable-rich' dietary pattern have a longer TL. This relation was partially explained by CRP but not by body fat.
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Vasianovich Y, Wellinger RJ. Life and Death of Yeast Telomerase RNA. J Mol Biol 2017; 429:3242-3254. [PMID: 28115201 DOI: 10.1016/j.jmb.2017.01.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Revised: 01/10/2017] [Accepted: 01/14/2017] [Indexed: 12/20/2022]
Abstract
Telomerase reverse transcriptase elongates telomeres to overcome their natural attrition and allow unlimited cellular proliferation, a characteristic shared by stem cells and the majority of malignant cancerous cells. The telomerase holoenzyme comprises a core RNA molecule, a catalytic protein subunit, and other accessory proteins. Malfunction of certain telomerase components can cause serious genetic disorders including dyskeratosis congenita and aplastic anaemia. A hierarchy of tightly regulated steps constitutes the process of telomerase biogenesis, which, if interrupted or misregulated, can impede the production of a functional enzyme and severely affect telomere maintenance. Here, we take a closer look at the budding yeast telomerase RNA component, TLC1, in its long lifetime journey around the cell. We review the extensive knowledge on TLC1 transcription and processing. We focus on exciting recent studies on telomerase assembly, trafficking, and nuclear dynamics, which for the first time unveil striking similarities between the yeast and human telomerase ribonucleoproteins. Finally, we identify questions yet to be answered and new directions to be followed, which, in the future, might improve our knowledge of telomerase biology and trigger the development of new therapies against cancer and other telomerase-related diseases.
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Affiliation(s)
- Yulia Vasianovich
- Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Applied Cancer Research Pavillion, 3201 rue Jean-Mignault, Sherbrooke, Quebec, J1E 4K8, Canada.
| | - Raymund J Wellinger
- Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Applied Cancer Research Pavillion, 3201 rue Jean-Mignault, Sherbrooke, Quebec, J1E 4K8, Canada.
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37
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Piqueret-Stephan L, Ricoul M, Hempel WM, Sabatier L. Replication Timing of Human Telomeres is Conserved during Immortalization and Influenced by Respective Subtelomeres. Sci Rep 2016; 6:32510. [PMID: 27587191 PMCID: PMC5009427 DOI: 10.1038/srep32510] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2016] [Accepted: 08/05/2016] [Indexed: 12/16/2022] Open
Abstract
Telomeres are specific structures that protect chromosome ends and act as a biological clock, preventing normal cells from replicating indefinitely. Mammalian telomeres are replicated throughout S-phase in a predetermined order. However, the mechanism of this regulation is still unknown. We wished to investigate this phenomenon under physiological conditions in a changing environment, such as the immortalization process to better understand the mechanism for its control. We thus examined the timing of human telomere replication in normal and SV40 immortalized cells, which are cytogenetically very similar to cancer cells. We found that the timing of telomere replication was globally conserved under different conditions during the immortalization process. The timing of telomere replication was conserved despite changes in telomere length due to endogenous telomerase reactivation, in duplicated homologous chromosomes, and in rearranged chromosomes. Importantly, translocated telomeres, possessing their initial subtelomere, retained the replication timing of their homolog, independently of the proportion of the translocated arm, even when the remaining flanking DNA is restricted to its subtelomere, the closest chromosome-specific sequences (inferior to 500 kb). Our observations support the notion that subtelomere regions strongly influence the replication timing of the associated telomere.
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Affiliation(s)
- Laure Piqueret-Stephan
- PROCyTOX Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Fontenay-aux-Roses and Université Paris-Saclay, France
| | - Michelle Ricoul
- PROCyTOX Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Fontenay-aux-Roses and Université Paris-Saclay, France
| | - William M Hempel
- PROCyTOX Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Fontenay-aux-Roses and Université Paris-Saclay, France
| | - Laure Sabatier
- PROCyTOX Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Fontenay-aux-Roses and Université Paris-Saclay, France
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Mao P, Liu J, Zhang Z, Zhang H, Liu H, Gao S, Rong YS, Zhao Y. Homologous recombination-dependent repair of telomeric DSBs in proliferating human cells. Nat Commun 2016; 7:12154. [PMID: 27396625 PMCID: PMC4942568 DOI: 10.1038/ncomms12154] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 06/07/2016] [Indexed: 12/28/2022] Open
Abstract
Telomeres prevent chromosome ends from being recognized as double-stranded breaks (DSBs). Meanwhile, G/C-rich repetitive telomeric DNA is susceptible to attack by DNA-damaging agents. How cells balance the need to protect DNA ends and the need to repair DNA lesions in telomeres is unknown. Here we show that telomeric DSBs are efficiently repaired in proliferating cells, but are irreparable in stress-induced and replicatively senescent cells. Using the CRISPR-Cas9 technique, we specifically induce DSBs at telomeric or subtelomeric regions. We find that DSB repair (DSBR) at subtelomeres occurs in an error-prone manner resulting in small deletions, suggestive of NHEJ. However, DSBR in telomeres involves 'telomere-clustering', 3'-protruding C-rich telomeric ssDNA, and HR between sister-chromatid or interchromosomal telomeres. DSBR in telomeres is suppressed by deletion or inhibition of Rad51. These findings reveal proliferation-dependent DSBR in telomeres and suggest that telomeric HR, which is normally constitutively suppressed, is activated in the context of DSBR.
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Affiliation(s)
- Pingsu Mao
- Key Laboratory of Gene Engineering of the Ministry of Education, Department of Biochemistry, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
- Collaborative Innovation Center of High Performance Computing, National University of Defense Technology, Changsha 410073, China
| | - Jingfan Liu
- Key Laboratory of Gene Engineering of the Ministry of Education, Department of Biochemistry, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
- Collaborative Innovation Center of High Performance Computing, National University of Defense Technology, Changsha 410073, China
- Zhongshan Medical School, Sun Yat-sen University, Guangzhou 510006, China
| | - Zepeng Zhang
- Key Laboratory of Gene Engineering of the Ministry of Education, Department of Biochemistry, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Hong Zhang
- Key Laboratory of Gene Engineering of the Ministry of Education, Department of Biochemistry, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Haiying Liu
- Key Laboratory of Gene Engineering of the Ministry of Education, Department of Biochemistry, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
- Collaborative Innovation Center of High Performance Computing, National University of Defense Technology, Changsha 410073, China
| | - Song Gao
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou 510060, China
| | - Yikang S. Rong
- Key Laboratory of Gene Engineering of the Ministry of Education, Department of Biochemistry, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Yong Zhao
- Key Laboratory of Gene Engineering of the Ministry of Education, Department of Biochemistry, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
- Collaborative Innovation Center of High Performance Computing, National University of Defense Technology, Changsha 410073, China
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A molecular biology and phase II study of imetelstat (GRN163L) in children with recurrent or refractory central nervous system malignancies: a pediatric brain tumor consortium study. J Neurooncol 2016; 129:443-451. [PMID: 27350411 DOI: 10.1007/s11060-016-2189-7] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 06/21/2016] [Indexed: 12/30/2022]
Abstract
Telomerase activation is critical in many cancers including central nervous system (CNS) tumors. Imetelstat is an oligonucleotide that binds to the template region of the RNA component of telomerase, inhibiting its enzymatic activity. We conducted an investigator-sponsored molecular biology (MB) and phase II study to estimate inhibition of tumor telomerase activity and sustained responses by imetelstat in children with recurrent CNS malignancies. In the MB study, patients with recurrent medulloblastoma, high-grade glioma (HGG) or ependymoma undergoing resection received one dose of imetelstat as a 2-h intravenous infusion at 285 mg/m(2), 12-24 h before surgery. Telomerase activity was evaluated in fresh tumor from surgery. Post-surgery and in the phase II study, patients received imetelstat IV (days 1 and 8 q21-days) at 285 mg/m(2). Imetelstat pharmacokinetic and pharmacodynamic studies were performed. Of two evaluable patients on the MB trial, intratumoral telomerase activity was inhibited by 95 % compared to baseline archival tissue in one patient and was inevaluable in one patient. Forty-two patients (40 evaluable for toxicity) were enrolled: 9 medulloblastomas, 18 HGG, 4 ependymomas, 9 diffuse intrinsic pontine gliomas. Most common grade 3/4 toxicities included thrombocytopenia (32.5 %), lymphopenia (17.5 %), neutropenia (12.5 %), ALT (7.5 %) and AST (5 %) elevation. Two patients died of intratumoral hemorrhage secondary to thrombocytopenia leading to premature study closure. No objective responses were observed. Telomerase inhibition was observed in peripheral blood mononuclear cells (PBMCs) for at least 8 days. Imetelstat demonstrated intratumoral and PBMC target inhibition; the regimen proved too toxic in children with recurrent CNS tumors.
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Abstract
UNLABELLED Telomeres progressively shorten throughout life. A hallmark of advanced malignancies is the ability for continuous cell divisions that almost universally correlates with the stabilization of telomere length by the reactivation of telomerase. The repression of telomerase and shorter telomeres in humans may have evolved, in part, as an anticancer protection mechanism. Although there is still much we do not understand about the regulation of telomerase, it remains a very attractive and novel target for cancer therapeutics. This review focuses on the current state of advances in the telomerase area, identifies outstanding questions, and addresses areas and methods that need refinement. SIGNIFICANCE Despite many recent advances, telomerase remains a challenging target for cancer therapy. There are few telomerase-directed therapies, and many of the assays used to measure telomeres and telomerase have serious limitations. This review provides an overview of the current state of the field and how recent advances could affect future research and treatment approaches. Cancer Discov; 6(6); 584-93. ©2016 AACR.
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Affiliation(s)
- Jerry W Shay
- Department of Cell Biology, The University of Texas Southwestern Medical Center, Dallas, Texas. Center of Excellence in Genomic Medicine Research, King Abdulaziz University, Jeddah, Saudi Arabia.
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41
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Carulli L, Anzivino C, Baldelli E, Zenobii MF, Rocchi MBL, Bertolotti M. Telomere length elongation after weight loss intervention in obese adults. Mol Genet Metab 2016; 118:138-42. [PMID: 27157420 DOI: 10.1016/j.ymgme.2016.04.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Revised: 04/10/2016] [Accepted: 04/11/2016] [Indexed: 01/26/2023]
Abstract
INTRODUCTION Telomeres may be considered markers of biological aging, shorter telomere length is associated with some age-related diseases; in several studies short telomere length has also been associated to obesity in adults and adolescents. However the relationship between telomere complex functions and obesity is still not clear. Aim of the study was to assess telomere length (TL) in adults' obese subjects before and after weight loss obtained by placement of bioenteric intragastric balloon (BIB) for 6months. METHODS We enrolled 42 obese subjects before and after BIB placement as weight loss intervention. Blood samples were collected in order to obtain DNA from leukocyte to measure TL by quantitative PCR. RESULTS Data were analyzed only in 37 subjects with complete data; all presented important body weight loss (124.06±26.7 vs 105.40±23.14, p<0.001) and more interesting they presented a significant increase in TL (3.58±0.83 vs 5.61±3.29, p<0.001). Moreover we observed a significant positive correlation between TL elongation and weight loss (r=0.44, p=0.007) as well as an inverse correlation between TL at baseline and TL elongation (r=-0.35, p=0.03).The predictors of TL elongation were once again weight loss and short TL at baseline (respectively p=0.007 and p=0.003). CONCLUSIONS Our study shows that weight loss is associated to telomere lengthening in a positive correlation: the greater weight loss the greater telomere lengthening; moreover telomere lengthening is more significant in those subjects with shortest telomeres at baseline.
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Affiliation(s)
- L Carulli
- Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Italy.
| | - C Anzivino
- Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Italy
| | - E Baldelli
- Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Italy
| | - M F Zenobii
- Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Italy
| | - M B L Rocchi
- Department of Biomolecular Sciences, University of Urbino, Urbino, Italy
| | - M Bertolotti
- Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Italy
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Ge Y, Wu S, Xue Y, Tao J, Li F, Chen Y, Liu H, Ma W, Huang J, Zhao Y. Preferential extension of short telomeres induced by low extracellular pH. Nucleic Acids Res 2016; 44:8086-96. [PMID: 27220467 PMCID: PMC5041450 DOI: 10.1093/nar/gkw464] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2015] [Accepted: 05/17/2016] [Indexed: 01/07/2023] Open
Abstract
The majority of tumor cells overcome proliferative limit by expressing telomerase. Whether or not telomerase preferentially extends the shortest telomeres is still under debate. When human cancer cells are cultured at neutral pH, telomerase extends telomeres in telomere length-independent manner. However, the microenvironment of tumor is slightly acidic, and it is not yet known how this influences telomerase action. Here, we examine telomere length homeostasis in tumor cells cultured at pHe 6.8. The results indicate that telomerase preferentially extends short telomeres, such that telomere length distribution narrows and telomeres become nearly uniform in size. After growth at pHe 6.8, the expression of telomerase, TRF1, TRF2 and TIN2 decreases, and the abundance of Cajal bodies decreases. Therefore, telomerase are insufficient for extending every telomere and shorter telomeres bearing less shelterin proteins are more accessible for telomerase recruitment. The findings support the ‘protein-counting mechanism’ in which extended and unextended state of telomere is determined by the number of associated shelterin proteins and the abundance of telomerase. Decreased expression of telomerase and preferential extension of short telomeres have important implications for tumor cell viability, and generate a strong rationale for research on telomerase-targeted anti-cancer therapeutics.
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Affiliation(s)
- Yuanlong Ge
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China Collaborative Innovation Center of High Performance Computing, National University of Defense Technology, Changsha 410073, China Zhongshan Medical School, Sun Yat-sen University, Guangzhou 510006, P. R. China
| | - Shu Wu
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Yong Xue
- Jiangsu Key Laboratory of Marine Pharmaceutical Compound Screening, Huaihai Institute of Technology, Lianyungang 222005, China
| | - Jun Tao
- Department of Hypertension and Vascular Disease, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou 510006, China
| | - Feng Li
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Yanlian Chen
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China Collaborative Innovation Center of High Performance Computing, National University of Defense Technology, Changsha 410073, China
| | - Haiying Liu
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China Collaborative Innovation Center of High Performance Computing, National University of Defense Technology, Changsha 410073, China
| | - Wenbin Ma
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Junjiu Huang
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Yong Zhao
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China Collaborative Innovation Center of High Performance Computing, National University of Defense Technology, Changsha 410073, China
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Zhang Y, Wu Y, Mao P, Li F, Han X, Zhang Y, Jiang S, Chen Y, Huang J, Liu D, Zhao Y, Ma W, Songyang Z. Cold-inducible RNA-binding protein CIRP/hnRNP A18 regulates telomerase activity in a temperature-dependent manner. Nucleic Acids Res 2015; 44:761-75. [PMID: 26673712 PMCID: PMC4737163 DOI: 10.1093/nar/gkv1465] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Accepted: 12/01/2015] [Indexed: 01/22/2023] Open
Abstract
The telomerase is responsible for adding telomeric repeats to chromosomal ends and consists of the reverse transcriptase TERT and the RNA subunit TERC. The expression and activity of the telomerase are tightly regulated, and aberrant activation of the telomerase has been observed in >85% of human cancers. To better understand telomerase regulation, we performed immunoprecipitations coupled with mass spectrometry (IP-MS) and identified cold inducible RNA-binding protein (CIRP or hnRNP A18) as a telomerase-interacting factor. We have found that CIRP is necessary to maintain telomerase activities at both 32°C and 37°C. Furthermore, inhibition of CIRP by CRISPR-Cas9 or siRNA knockdown led to reduced telomerase activities and shortened telomere length, suggesting an important role of CIRP in telomere maintenance. We also provide evidence here that CIRP associates with the active telomerase complex through direct binding of TERC and regulates Cajal body localization of the telomerase. In addition, CIRP regulates the level of TERT mRNAs. At the lower temperature, TERT mRNA is upregulated in a CIRP-dependent manner to compensate for reduced telomerase activities. Taken together, these findings highlight the dual roles that CIRP plays in regulating TERT and TERC, and reveal a new class of telomerase modulators in response to hypothermia conditions.
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Affiliation(s)
- Youwei Zhang
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China Collaborative Innovation Center for Cancer Medicine, Institute of Healthy Aging Research, Sun Yat-sen University, Guangzhou 510006, China
| | - Yangxiu Wu
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Pingsu Mao
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Feng Li
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Xin Han
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Yi Zhang
- Verna and Marrs Mclean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Shuai Jiang
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Yuxi Chen
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Junjiu Huang
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Dan Liu
- Verna and Marrs Mclean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Yong Zhao
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Wenbin Ma
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China Collaborative Innovation Center for Cancer Medicine, Institute of Healthy Aging Research, Sun Yat-sen University, Guangzhou 510006, China
| | - Zhou Songyang
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China Collaborative Innovation Center for Cancer Medicine, Institute of Healthy Aging Research, Sun Yat-sen University, Guangzhou 510006, China Verna and Marrs Mclean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
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The Insertion in Fingers Domain in Human Telomerase Can Mediate Enzyme Processivity and Telomerase Recruitment to Telomeres in a TPP1-Dependent Manner. Mol Cell Biol 2015; 36:210-22. [PMID: 26503784 DOI: 10.1128/mcb.00746-15] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 10/19/2015] [Indexed: 01/11/2023] Open
Abstract
In most human cancer cells, cellular immortalization relies on the activation and recruitment of telomerase to telomeres. The telomere-binding protein TPP1 and the TEN domain of the telomerase catalytic subunit TERT regulate telomerase recruitment. TERT contains a unique domain, called the insertion in fingers domain (IFD), located within the conserved reverse transcriptase domain. We report the role of specific hTERT IFD residues in the regulation of telomerase activity and processivity, recruitment to telomeres, and cell survival. One hTERT IFD variant, hTERT-L805A, with reduced activity and processivity showed impaired telomere association, which could be partially rescued by overexpression of TPP1-POT1. Another previously reported hTERT IFD mutant enzyme with similarly low levels of activity and processivity, hTERT-V791Y, displayed defects in telomere binding and was insensitive to TPP1-POT1 overexpression. Our results provide the first evidence that the IFD can mediate enzyme processivity and telomerase recruitment to telomeres in a TPP1-dependent manner. Moreover, unlike hTERT-V791Y, hTERT-V763S, a variant with reduced activity but increased processivity, and hTERT-L805A, could both immortalize limited-life-span cells, but cells expressing these two mutant enzymes displayed growth defects, increased apoptosis, DNA damage at telomeres, and short telomeres. Our results highlight the importance of the IFD in maintaining short telomeres and in cell survival.
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A novel telomerase substrate precursor rapidly induces telomere dysfunction in telomerase positive cancer cells but not telomerase silent normal cells. Oncoscience 2015; 2:693-5. [PMID: 26425659 PMCID: PMC4580061 DOI: 10.18632/oncoscience.213] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 08/17/2015] [Indexed: 12/22/2022] Open
Abstract
Although telomerase is an almost universal target for cancer therapy, there has been no effective telomerase targeted inhibitor that has progressed to late stage human clinical trials. Recently, we reported that a telomerase-mediated telomere-disrupting compound, 6-thio-2′-deoxyguanosine (6-thio-dG), was very effective at targeting telomerase positive cancer cells while sparing telomerase silent normal cells. 6-thio-dG, a nucleoside analogue of the already-approved drug 6-thioguanine, is incorporated into telomeres by telomerase, resulting in disruption of the telomere-protecting shelterin complex. This disruption leads to Telomere dysfunction-Induced Foci (TIFs) formation and rapid cell death for the vast majority of cancer cells. Since most chemotherapies eventually fail due to drug acquired resistance, novel drugs such as 6-thio-dG, as a single first line agent or in the maintenance setting, may represent an effective new treatment for cancer patients.
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Wu S, Ge Y, Huang L, Liu H, Xue Y, Zhao Y. BRG1, the ATPase subunit of SWI/SNF chromatin remodeling complex, interacts with HDAC2 to modulate telomerase expression in human cancer cells. Cell Cycle 2015; 13:2869-78. [PMID: 25486475 DOI: 10.4161/15384101.2014.946834] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Telomerase is often upregulated during initiation and/or progression of human tumors, suggesting that repression of telomerase might inhibit cancer growth or progression. Here, we report that BRG1, the ATPase subunit of the SWI/SNF chromatin remodeling complex, is a general suppressor of hTERT transcription in human cancer cells. While overexpression of BRG1 inhibits hTERT transcription, depletion of BRG1 stimulates transcription of hTERT, leading to higher telomerase activity and longer telomeres. Chromatin-immunoprecipitation assays revealed that BRG1 binds to the transcription start site (TSS) of the hTERT promoter and forms a ternary complex with histone deacetylase 2 (HDAC2). BRG1 remodels chromatin structure to facilitate the action of HDAC2, leading to deacetylation of H3K9ac and H4ac at the TSS and suppression of hTERT transcription. On the other hand, β-catenin binds to the TSS and stimulates hTERT transcription. Thus, BRG1/HDAC2 and β-catenin constitute a manipulative apparatus at the TSS to play opposite but complementary roles in regulating hTERT expression. These results uncover a yin-yang mechanism in modulating hTERT transcription and provide explanation for limited transcription of hTERT in human cancer cells. BRG1/HDAC2 may have a potential as an anti-cancer therapeutic and/or for reactivating cellular proliferative capacity in the context of in vitro tissue engineering.
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Affiliation(s)
- Shu Wu
- a The School of Life Sciences ; Tsinghua University ; Beijing , PR China
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Chen S, Li Q, Xu Y, Li H, Ding X. Gold Nanorods Bioconjugates for Intracellular Delivery and Cancer Cell Apoptosis. ACTA ACUST UNITED AC 2015; 20:418-22. [DOI: 10.1177/2211068215576871] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2014] [Indexed: 11/15/2022]
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Simon NM, Walton ZE, Bui E, Prescott J, Hoge E, Keshaviah A, Schwarz N, Dryman T, Ojserkis RA, Kovachy B, Mischoulon D, Worthington J, DeVivo I, Fava M, Wong KK. Telomere length and telomerase in a well-characterized sample of individuals with major depressive disorder compared to controls. Psychoneuroendocrinology 2015; 58:9-22. [PMID: 25932992 PMCID: PMC4461511 DOI: 10.1016/j.psyneuen.2015.04.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Revised: 04/03/2015] [Accepted: 04/04/2015] [Indexed: 01/07/2023]
Abstract
BACKGROUND Leukocyte telomere length (LTL) is a marker of cellular turnover and oxidative stress. Studies suggest major depressive disorder (MDD) is associated with oxidative stress, but examinations of MDD and LTL have yielded mixed results, likely because of differences in measurement methods and unmeasured confounding. This study examined LTL and telomerase activity in 166 individuals with MDD compared to 166 age- and gender-matched matched controls free of any psychiatric disorder, using well-validated assays and clinical assessment methods, and controlling for a range of potential confounders. METHODS Subjects aged 18 to 70 were evaluated by trained raters and provided blood for LTL and telomerase activity measurement. LTL was assayed using Southern blot and replicated with qPCR, and telomerase activity was assayed with a repeat amplification protocol using a commercial kit. RESULTS There was no significant difference in telomere length for individuals with MDD [mean (SD)=9.1 (3.0)kbp] compared to controls [mean(SD)=8.9(2.5)kbp] measured by Southern blot (p=0.65) or by confirmatory qPCR (p=0.91) assays. Controlling for potential confounders did not alter the results. Telomerase activity did not differ by MDD diagnosis overall (p=0.40), but the effect of MDD was significantly modified by gender (t(299)=2.67, p=0.0079) even after controlling for potential confounders, with telomerase activity significantly greater only in males with MDD versus controls. CONCLUSION Our well-characterized, well-powered examination of concurrently assessed telomere length and telomerase activity in individuals with clinically significant, chronic MDD and matched controls failed to provide strong evidence of an association of MDD with shorter LTL, while telomerase activity was higher in men with MDD [corrected].
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Affiliation(s)
- Naomi M. Simon
- Department of Psychiatry, Massachusetts General Hospital, Boston, MA, United States,Harvard Medical School, Boston, MA, United States
| | | | - Eric Bui
- Department of Psychiatry, Massachusetts General Hospital, Boston, MA, United States,Harvard Medical School, Boston, MA, United States
| | - Jennifer Prescott
- Program in Genetic Epidemiology and Statistical Genetics, Department of Epidemiology, Harvard School of Public Health, Boston, MA, United States,Dana-Farber Cancer Institute, Boston, MA, United States
| | - Elizabeth Hoge
- Department of Psychiatry, Massachusetts General Hospital, Boston, MA, United States,Harvard Medical School, Boston, MA, United States
| | - Aparna Keshaviah
- Department of Psychiatry, Massachusetts General Hospital, Boston, MA, United States
| | - Noah Schwarz
- Department of Psychiatry, Massachusetts General Hospital, Boston, MA, United States
| | - Taylor Dryman
- Department of Psychiatry, Massachusetts General Hospital, Boston, MA, United States
| | - Rebecca A. Ojserkis
- Department of Psychiatry, Massachusetts General Hospital, Boston, MA, United States
| | - Benjamin Kovachy
- Department of Psychiatry, Massachusetts General Hospital, Boston, MA, United States
| | - David Mischoulon
- Department of Psychiatry, Massachusetts General Hospital, Boston, MA, United States,Harvard Medical School, Boston, MA, United States
| | - John Worthington
- Department of Psychiatry, Massachusetts General Hospital, Boston, MA, United States,Harvard Medical School, Boston, MA, United States
| | - Immaculata DeVivo
- Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, United States,Program in Genetic Epidemiology and Statistical Genetics, Department of Epidemiology, Harvard School of Public Health, Boston, MA, United States
| | - Maurizio Fava
- Department of Psychiatry, Massachusetts General Hospital, Boston, MA, United States,Harvard Medical School, Boston, MA, United States
| | - Kwok-Kin Wong
- Harvard Medical School, Boston, MA, United States,Dana-Farber Cancer Institute, Boston, MA, United States
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Abstract
While telomerase is expressed in ~90% of primary human tumors, most somatic tissue cells except transiently proliferating stem-like cells do not have detectable telomerase activity (Shay and Wright, 1996; Shay and Wright, 2001). Telomeres progressively shorten with each cell division in normal cells, including proliferating stem-like cells, due to the end replication (lagging strand synthesis) problem and other causes such as oxidative damage, therefore all somatic cells have limited cell proliferation capacity (Hayflick limit) (Hayflick and Moorhead, 1961; Olovnikov, 1973). The progressive telomere shortening eventually leads to growth arrest in normal cells, which is known as replicative senescence (Shay et al., 1991). Once telomerase is activated in cancer cells, telomere length is stabilized by the addition of TTAGGG repeats to the end of chromosomes, thus enabling the limitless continuation of cell division (Shay and Wright, 1996; Shay and Wright, 2001). Therefore, the link between aging and cancer can be partially explained by telomere biology. There are many rapid and convenient methods to study telomere biology such as Telomere Restriction Fragment (TRF), Telomere Repeat Amplification Protocol (TRAP) (Mender and Shay, 2015b) and Telomere dysfunction Induced Foci (TIF) analysis (Mender and Shay, 2015a). In this protocol paper we describe Telomere Restriction Fragment (TRF) analysis to determine average telomeric length of cells. Telomeric length can be indirectly measured by a technique called Telomere Restriction Fragment analysis (TRF). This technique is a modified Southern blot, which measures the heterogeneous range of telomere lengths in a cell population using the length distribution of the terminal restriction fragments (Harley et al., 1990; Ouellette et al., 2000). This method can be used in eukaryotic cells. The description below focuses on the measurement of human cancer cells telomere length. The principle of this method relies on the lack of restriction enzyme recognition sites within TTAGGG tandem telomeric repeats, therefore digestion of genomic DNA, not telomeric DNA, with a combination of 6 base restriction endonucleases reduces genomic DNA size to less than 800 bp.
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Affiliation(s)
- Ilgen Mender
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, USA
| | - Jerry W Shay
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, USA; Center for Excellence in Genomics Medicine Research, King Abdulaziz University, Jeddah, Saudi Arabia
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Jodczyk S, Pearson JF, Aitchison A, Miller AL, Hampton MB, Kennedy MA. Telomere length measurement on the Roche LightCycler 480 Platform. Genet Test Mol Biomarkers 2014; 19:63-8. [PMID: 25535668 DOI: 10.1089/gtmb.2014.0208] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND The average length of telomeres as measured in genomic DNA from human peripheral blood leukocytes is proving to be a potential biomarker of great interest, particularly with respect to studies of aging, specific diseases, and the effects of various stresses on overall health. AIMS The aim of this study was to establish an effective real-time quantitative polymerase chain reaction (qPCR) method for telomere length measurement on the Roche LightCycler® 480 (LC480) real-time PCR platform. METHODS Measurement of relative average telomere length was achieved by comparing products amplified from telomere-specific primers and single copy reference gene primers in a ratio (T/S). RESULTS Extensive testing led us to conclude that a modification of the original two-plate T/S assay was more compatible with this platform than the recently developed single-plate assay, and that choice of hot-start Taq polymerase and intercalating dye were critical factors. CONCLUSIONS This modified assay generates reliable measurements as judged by correlation with data derived by the telomeric restriction fragment Southern blot-based method.
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Affiliation(s)
- Sarah Jodczyk
- 1 Gene Structure and Function Laboratory, Department of Pathology, University of Otago , Christchurch, Christchurch, New Zealand
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