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Alanazi AFR, Parkinson GN, Haider S. Structural Motifs at the Telomeres and Their Role in Regulatory Pathways. Biochemistry 2024; 63:827-842. [PMID: 38481135 PMCID: PMC10993422 DOI: 10.1021/acs.biochem.4c00023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Telomeres are specialized structures, found at the ends of linear chromosomes in eukaryotic cells, that play a crucial role in maintaining the stability and integrity of genomes. They are composed of repetitive DNA sequences, ssDNA overhangs, and several associated proteins. The length of telomeres is linked to cellular aging in humans, and deficiencies in their maintenance are associated with various diseases. Key structural motifs at the telomeres serve to protect vulnerable chromosomal ends. Telomeric DNA also has the ability to form diverse complex DNA higher-order structures, including T-loops, D-loops, R-loops, G-loops, G-quadruplexes, and i-motifs, in the complementary C-rich strand. While many essential proteins at telomeres have been identified, the intricacies of their interactions and structural details are still not fully understood. This Perspective highlights recent advancements in comprehending the structures associated with human telomeres. It emphasizes the significance of telomeres, explores various telomeric structural motifs, and delves into the structural biology surrounding telomeres and telomerase. Furthermore, telomeric loops, their topologies, and the associated proteins that contribute to the safeguarding of telomeres are discussed.
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Affiliation(s)
- Abeer F R Alanazi
- UCL School of Pharmacy, University College London, London WC1N 1AX, United Kingdom
| | - Gary N Parkinson
- UCL School of Pharmacy, University College London, London WC1N 1AX, United Kingdom
| | - Shozeb Haider
- UCL School of Pharmacy, University College London, London WC1N 1AX, United Kingdom
- UCL Centre for Advanced Research Computing, University College London, London WC1H 9RN, United Kingdom
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2
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Das A, Giri AK, Bhattacharjee P. Targeting 'histone mark': Advanced approaches in epigenetic regulation of telomere dynamics in cancer. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2024; 1867:195007. [PMID: 38237857 DOI: 10.1016/j.bbagrm.2024.195007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 01/09/2024] [Accepted: 01/10/2024] [Indexed: 01/23/2024]
Abstract
Telomere integrity is required for the maintenance of genome stability and prevention of oncogenic transformation of cells. Recent evidence suggests the presence of epigenetic modifications as an important regulator of mammalian telomeres. Telomeric and subtelomeric regions are rich in epigenetic marks that regulate telomere length majorly through DNA methylation and post-translational histone modifications. Specific histone modifying enzymes play an integral role in establishing telomeric histone codes necessary for the maintenance of structural integrity. Alterations of crucial histone moieties and histone modifiers cause deregulations in the telomeric chromatin leading to carcinogenic manifestations. This review delves into the significance of histone modifications and their influence on telomere dynamics concerning cancer. Additionally, it highlights the existing research gaps that hold the potential to drive the development of therapeutic interventions targeting the telomere epigenome.
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Affiliation(s)
- Ankita Das
- Department of Environmental Science, University of Calcutta, Kolkata 700019, India; Department of Zoology, University of Calcutta, Kolkata 700019, India
| | - Ashok K Giri
- Molecular Genetics Division, CSIR-Indian Institute of Chemical Biology, Kolkata 700032, India
| | - Pritha Bhattacharjee
- Department of Environmental Science, University of Calcutta, Kolkata 700019, India.
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3
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Zafirovic S, Macvanin M, Stanimirovic J, Obradovic M, Radovanovic J, Melih I, Isenovic E. Association Between Telomere Length and Cardiovascular Risk: Pharmacological Treatments Affecting Telomeres and Telomerase Activity. Curr Vasc Pharmacol 2022; 20:465-474. [PMID: 35986545 DOI: 10.2174/1570161120666220819164240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 06/03/2022] [Accepted: 06/06/2022] [Indexed: 01/25/2023]
Abstract
Telomeres represent the ends of chromosomes, and they are composed of an extensive number of - TTAGGG nucleotide sequence repeats in humans. Telomeres prevent chromosome degradation, participate in stabilization, and regulate the DNA repair system. Inflammation and oxidative stress have been identified as important processes causing cardiovascular disease and accelerating telomere shortening rate. This review investigates the link between telomere length and pathological vascular conditions from experimental and human studies. Also, we discuss pharmacological treatments affecting telomeres and telomerase activity.
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Affiliation(s)
- Sonja Zafirovic
- Department of Radiobiology and Molecular Genetics, VINČA Institute of Nuclear Sciences - National Institute of the Republic of Serbia, University of Belgrade, Belgrade, Serbia
| | - Mirjana Macvanin
- Department of Radiobiology and Molecular Genetics, VINČA Institute of Nuclear Sciences - National Institute of the Republic of Serbia, University of Belgrade, Belgrade, Serbia
| | - Julijana Stanimirovic
- Department of Radiobiology and Molecular Genetics, VINČA Institute of Nuclear Sciences - National Institute of the Republic of Serbia, University of Belgrade, Belgrade, Serbia
| | - Milan Obradovic
- Department of Radiobiology and Molecular Genetics, VINČA Institute of Nuclear Sciences - National Institute of the Republic of Serbia, University of Belgrade, Belgrade, Serbia
| | - Jelena Radovanovic
- Department of Radiobiology and Molecular Genetics, VINČA Institute of Nuclear Sciences - National Institute of the Republic of Serbia, University of Belgrade, Belgrade, Serbia
| | - Irena Melih
- Faculty of Stomatology, Pancevo, University Business Academy, 21000 Novi Sad, Serbia
| | - Esma Isenovic
- Department of Radiobiology and Molecular Genetics, VINČA Institute of Nuclear Sciences - National Institute of the Republic of Serbia, University of Belgrade, Belgrade, Serbia
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4
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Yang L, Zhang H, Zhang X, Tang Y, Wu Z, Wang Y, Huang H, Fu X, Liu J, Hogendoorn PC, Cheng H. Clinicopathologic and molecular features of denosumab-treated giant cell tumour of bone (GCTB): Analysis of 21 cases. Ann Diagn Pathol 2022; 57:151882. [DOI: 10.1016/j.anndiagpath.2021.151882] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 12/12/2021] [Accepted: 12/14/2021] [Indexed: 01/15/2023]
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5
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Lafon-Hughes L, Fernández Villamil SH, Vilchez Larrea SC. Tankyrase inhibitors hinder Trypanosoma cruzi infection by altering host-cell signalling pathways. Parasitology 2021; 148:1680-1690. [PMID: 35060470 PMCID: PMC11010053 DOI: 10.1017/s0031182021001402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 06/25/2021] [Accepted: 07/28/2021] [Indexed: 11/06/2022]
Abstract
Chagas disease is a potentially life-threatening protozoan infection affecting around 8 million people, for which only chemotherapies with limited efficacy and severe adverse secondary effects are available. The aetiological agent, Trypanosoma cruzi, displays varied cell invading tactics and triggers different host cell signals, including the Wnt/β-catenin pathway. Poly(ADP-ribose) (PAR) can be synthetized by certain members of the poly(ADP-ribose) polymerase (PARP) family: PARP-1/-2 and Tankyrases-1/2 (TNKS). PAR homoeostasis participates in the host cell response to T. cruzi infection and TNKS are involved in Wnt signalling, among other pathways. Therefore, we hypothesized that TNKS inhibitors (TNKSi) could hamper T. cruzi infection. We showed that five TNKSi (FLALL9, MN64, XAV939, G007LK and OULL9) diminished T. cruzi infection of Vero cells. As most TNKSi did not affect the viability of axenically cultivated parasites, our results suggested that TNKSi were interfering with parasite–host cell signalling. Infection by T. cruzi induced nuclear translocation of β-catenin, as well as upregulation of TNF-α expression and secretion. These changes were hampered by TNKSi. Further signals should be monitored in this model and in vivo. As a TNKSi has entered cancer clinical trials with promising results, our findings encourage further studies aiming at drug repurposing strategies.
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Affiliation(s)
- Laura Lafon-Hughes
- Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, Uruguay
- Grupo de Biofisicoquímica, Departamento de Ciencias Biológicas, Centro Universitario Regional Litoral Norte, Universidad de la República (CENUR-UdelaR), Salto, Uruguay
| | - Silvia H. Fernández Villamil
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular ‘Dr. Héctor N. Torres’, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Autónoma de Buenos Aires, Argentina
- Departamento de Química Biológica, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina
| | - Salomé C. Vilchez Larrea
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular ‘Dr. Héctor N. Torres’, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Autónoma de Buenos Aires, Argentina
- Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina
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6
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Dos Santos GA, Viana NI, Pimenta R, de Camargo JA, T Reis S, Moreira Leite KR, Srougi M. Telomeric zinc-finger associated protein (TZAP) in cancer biology: friend or foe? MOLECULAR BIOLOGY RESEARCH COMMUNICATIONS 2021; 10:121-129. [PMID: 34476265 DOI: 10.22099/mbrc.2021.40106.1607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 09/30/2022]
Abstract
The new identified protein telomeric zinc-finger associated protein (TZAP) is a negative regulator of telomere length. Since telomere length and telomere maintenance mechanisms are essential to cancer progression, TZAP is considered a new player in cancer biology. Here we aimed to analyze TZAP using the Cancer Genome Atlas data in a Pan-Cancer approach. We gathering data from TCGA Pan-Cancer studies utilizing cBioPortal, GEPIA and UALCAN. In total we analyzed 33 types of cancer (n=9664) and their respective controls (n=711). TZAP is transcribed in all cancers but less than 5% of all tumors show any somatic changes. TZAP was downregulated in kidney chromophobe carcinoma, and upregulated in esophageal cancer, head and neck squamous cell carcinomas, kidney renal clear cell carcinoma and in liver hepatocellular carcinoma. Globally, TZAP expression is related to favorable prognosis, associated to better overall and disease-free survival. Looking to specific tumors, TZAP expression has a dual behavior. Its downregulation is associated with poor prognosis in cervical squamous cell carcinoma, in kidney renal clear cell carcinoma, kidney papillary cell carcinoma, lung adenocarcinoma and pancreas adenocarcinoma. On the contrary, in adrenocortical carcinoma, colon and rectal cancer, brain lower grade glioma and prostate adenocarcinoma the upregulation of TZAP is related with poor prognosis. TZAP expression has a positive correlation with TRF1 and TRF2 in normal tissue but not in cancer. Our analyses indicate that TZAP has an important role in oncology and may be considered as a potential biomarker.
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Affiliation(s)
- Gabriel Arantes Dos Santos
- Urology Department, Laboratory of Medical Investigation (LIM55), Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, SP, Brazil.,D'Or Institute for Research and Education (IDOR), Sao Paulo, Brazil
| | - Nayara Izabel Viana
- Urology Department, Laboratory of Medical Investigation (LIM55), Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, SP, Brazil.,Minas Gerais State University (UEMG), Passos, Minas Gerais, Brazil
| | - Ruan Pimenta
- Urology Department, Laboratory of Medical Investigation (LIM55), Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, SP, Brazil.,D'Or Institute for Research and Education (IDOR), Sao Paulo, Brazil
| | - Juliana Alves de Camargo
- Urology Department, Laboratory of Medical Investigation (LIM55), Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, SP, Brazil
| | - Sabrina T Reis
- Urology Department, Laboratory of Medical Investigation (LIM55), Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, SP, Brazil.,Minas Gerais State University (UEMG), Passos, Minas Gerais, Brazil.,Athens University Center (UniAtenas), Passos, Minas Gerais, Brazil
| | - Katia Ramos Moreira Leite
- Urology Department, Laboratory of Medical Investigation (LIM55), Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, SP, Brazil
| | - Miguel Srougi
- Urology Department, Laboratory of Medical Investigation (LIM55), Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, SP, Brazil.,D'Or Institute for Research and Education (IDOR), Sao Paulo, Brazil
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Telomere associated gene expression as well as TERT protein level and telomerase activity are altered in the ovarian follicles of aged mice. Sci Rep 2021; 11:15569. [PMID: 34330985 PMCID: PMC8324818 DOI: 10.1038/s41598-021-95239-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 07/05/2021] [Indexed: 01/23/2023] Open
Abstract
Telomeres cap the ends of eukaryotic chromosomes to maintain genomic stability and integrity during an organism’s lifespan. The length of telomeres inevitably shortens due to DNA replication, genotoxic agents, and biological aging. A limited number of cell types, e.g., stem cells, germline cells, and early embryos can elongate shortened telomeres via the enzymatic action of telomerase, which is composed of telomerase reverse transcriptase (TERT) and telomerase RNA component (Terc). Additionally, telomere-associated proteins including telomeric repeat binding factor 1 (TRF1) and 2 (TRF2), as well as protection of telomeres 1a (POT1a), bind to telomeres to maintain their structural integrity and length. During ovarian aging in mammals, telomeres progressively shorten, accompanied by fertility loss; however, the molecular mechanism underlying this attrition during follicle development remains unclear. In this study, the primary, secondary, preantral, and antral follicles were obtained either from 6-week-old adult (n = 19) or 52-week-old aged (n = 12) mice. We revealed that the Tert, Terc, Trf1, Trf2, and Pot1a gene expression (P < 0.001) and TERT protein (P < 0.01) levels significantly decreased in certain ovarian follicles of the aged group when compared to those of the adult group. Also, telomerase activity exhibited remarkable changes in the follicles of both groups. Consequently, altered telomere-associated gene expression and reduced TERT protein levels in the follicles of aged mice may be a determinant of telomere shortening during ovarian aging, and infertility appearing in the later decades of reproductive lifespan. Further investigations are required to determine the molecular mechanisms underlying these alterations in the follicles during ovarian aging.
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Zhou X, Li X, Wei W, Duan X, Zhang H, Ding M, Yao W, Wang Q, Wang W, Yang Y. Association between genetic polymorphisms of telomere pathway genes and hydrogen peroxide level in omethoate exposure workers. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2021; 82:103541. [PMID: 33161111 DOI: 10.1016/j.etap.2020.103541] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 10/15/2020] [Accepted: 10/30/2020] [Indexed: 06/11/2023]
Abstract
OBJECTIVE The aim of this study was to explore the association between genetic variations in telomere pathway genes and the level of hydrogen peroxide (H2O2) in omethoate exposure workers. METHODS A total of 180 omethoate exposure workers and 115 healthy controls were recruited. The level of H2O2 in plasma was determined with molybdenic acid colorimetry. Polymerase chain reaction and restriction fragment length was used to detect polymorphisms in POT1 rs1034794, POT1 rs10250202, TERF1 rs3863242, and TERT rs2736098. RESULTS The level of H2O2 in exposure group (4.26 ± 0.71) was significantly higher than that in control group (3.29 ± 0.46). Generalized linear models indicated that risk factors for the increase H2O2 level were exposure [β(95 % CI) = 0.951 (0.806, 1.096), P < 0.001] and AA + AT genotype in POT1 rs034794 [β(95 % CI) = 0.397 (0.049, 0.745), P = 0.025]. CONCLUSION The increase H2O2 level was associated with omethoate exposure and AA + AT genotypes in POT1 gene rs1034794. It provided a new idea that polymorphisms in telomere pathway genes may indirectly regulate telomere length by influencing oxidative stress.
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Affiliation(s)
- Xiaoshan Zhou
- Department of Occupational Health and Occupational Diseases, College of Public Health, Zhengzhou University, Zhengzhou, China
| | - Xinling Li
- Department of Occupational Health and Occupational Diseases, College of Public Health, Zhengzhou University, Zhengzhou, China
| | - Wan Wei
- Department of Occupational Health and Occupational Diseases, College of Public Health, Zhengzhou University, Zhengzhou, China
| | - Xiaoran Duan
- Department of Occupational Health and Occupational Diseases, College of Public Health, Zhengzhou University, Zhengzhou, China
| | - Hui Zhang
- Department of Occupational Health and Occupational Diseases, College of Public Health, Zhengzhou University, Zhengzhou, China
| | - Mingcui Ding
- Department of Occupational Health and Occupational Diseases, College of Public Health, Zhengzhou University, Zhengzhou, China
| | - Wu Yao
- Department of Occupational Health and Occupational Diseases, College of Public Health, Zhengzhou University, Zhengzhou, China
| | - Qi Wang
- Department of Occupational Health and Occupational Diseases, College of Public Health, Zhengzhou University, Zhengzhou, China
| | - Wei Wang
- Department of Occupational Health and Occupational Diseases, College of Public Health, Zhengzhou University, Zhengzhou, China; The Key Laboratory of Nanomedicine and Health Inspection of Zhengzhou, Zhengzhou, China
| | - Yongli Yang
- Department of Epidemiology and Biostatistics, College of Public Health, Zhengzhou University, Zhengzhou, China.
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9
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Effect of exercise on telomere length and telomere proteins expression in mdx mice. Mol Cell Biochem 2020; 470:189-197. [DOI: 10.1007/s11010-020-03761-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Accepted: 05/16/2020] [Indexed: 12/19/2022]
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10
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Maros ME, Schnaidt S, Balla P, Kelemen Z, Sapi Z, Szendroi M, Laszlo T, Forsyth R, Picci P, Krenacs T. In situ cell cycle analysis in giant cell tumor of bone reveals patients with elevated risk of reduced progression-free survival. Bone 2019; 127:188-198. [PMID: 31233932 DOI: 10.1016/j.bone.2019.06.022] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Revised: 05/23/2019] [Accepted: 06/21/2019] [Indexed: 12/21/2022]
Abstract
OBJECTIVE Giant cell tumor of bone (GCTB) is a frequently recurring locally aggressive osteolytic lesion, where pathological osteoclastogenesis and bone destruction are driven by neoplastic stromal cells. Here, we studied if cell cycle fractions within the mononuclear cell compartment of GCTB can predict its progression-free survival (PFS). METHODS 154 cases (100 primaries and 54 recurrent) from 139 patients of 40 progression events, was studied using tissue microarrays. Ploidy and in situ cell cycle progression related proteins including Ki67 and those linked with replication licensing (mcm2), G1-phase (cyclin D1, Cdk4), and S-G2-M-phase (cyclin A; Cdk2) fractions; cell cycle control (p21waf1) and repression (geminin), were tested. The Prentice-Williams-Peterson (PWP) gap-time models with the Akaike information criterion (AIC) were used for PFS analysis. RESULTS Cluster analysis showed good correlation between functionally related marker positive cell fractions indicating no major cell cycle arrested cell populations in GCTB. Increasing hazard of progression was statistically associated with the elevated post-G1/S-phase cell fractions. Univariate analysis revealed significant negative association of poly-/aneuploidy (p < 0.0001), and elevated cyclin A (p < 0.001), geminin (p = 0.015), mcm2 (p = 0.016), cyclin D1 (p = 0.022) and Ki67 (B56: p = 0.0543; and Mib1: p = 0.0564 -strong trend) positive cell fractions with PFS. The highest-ranked multivariate interaction model (AIC = 269.5) also included ploidy (HR 5.68, 95%CI: 2.62-12.31, p < 0.0001), mcm2 (p = 0.609), cyclin D1 (HR 1.89, 95%CI: 0.88-4.09, p = 0.105) and cyclin A (p < 0.0001). The first and second best prognostic models without interaction (AIC = 271.6) and the sensitivity analysis (AIC = 265.7) further confirmed the prognostic relevance of combining these markers. CONCLUSION Ploidy and elevated replication licensing (mcm2), G1-phase (cyclin D1) and post-G1 phase (cyclin A) marker positive cell fractions, indicating enhanced cell cycle progression, can assist in identifying GCTB patients with increased risk for a reduced PFS.
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Affiliation(s)
- Mate E Maros
- 1(st) Department of Pathology and Experimental Cancer Research, Semmelweis University, Budapest, Hungary; Department of Neuroradiology, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Sven Schnaidt
- Institute of Medical Biometry and Informatics, University of Heidelberg, Heidelberg, Germany
| | - Peter Balla
- 1(st) Department of Pathology and Experimental Cancer Research, Semmelweis University, Budapest, Hungary
| | - Zoltan Kelemen
- 1(st) Department of Pathology and Experimental Cancer Research, Semmelweis University, Budapest, Hungary
| | - Zoltan Sapi
- 1(st) Department of Pathology and Experimental Cancer Research, Semmelweis University, Budapest, Hungary
| | - Miklos Szendroi
- Department of Orthopedics, Semmelweis University, Budapest, Hungary
| | - Tamas Laszlo
- Department of Oto-Rhino-Laryngology, Head and Neck Surgery, Semmelweis University, Budapest, Hungary
| | - Ramses Forsyth
- Department of Anatomic Pathology, University of Brussels, Belgium
| | - Piero Picci
- Laboratory of Experimental Oncology, Institute of Orthopedics Rizzoli, Bologna, Italy
| | - Tibor Krenacs
- 1(st) Department of Pathology and Experimental Cancer Research, Semmelweis University, Budapest, Hungary.
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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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Yu Y, Tan R, Ren Q, Gao B, Sheng Z, Zhang J, Zheng X, Jiang Y, Lan L, Mao Z. POT1 inhibits the efficiency but promotes the fidelity of nonhomologous end joining at non-telomeric DNA regions. Aging (Albany NY) 2019; 9:2529-2543. [PMID: 29227966 PMCID: PMC5764391 DOI: 10.18632/aging.101339] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2017] [Accepted: 12/01/2017] [Indexed: 11/25/2022]
Abstract
Robust DNA double strand break (DSB) repair and stabilized telomeres help maintain genome integrity, preventing the onset of aging or tumorigenesis. POT1 is one of the six factors in the shelterin complex, which protects telomeres from being recognized as DNA damages. TRF1 and TRF2, two other shelterin proteins, have been shown to participate in DNA DSB repair at non-telomeric regions, but whether POT1, which binds to single strand telomeric DNA at chromosomal ends, is involved in DNA DSB repair has not been assessed. Here we found that POT1 arrives at DNA damage sites upon the occurrence of DNA DSBs. It suppresses the efficiency of nonhomologous end joining (NHEJ), the major pathway for fixing DNA DSBs in mammals, but surprisingly promotes NHEJ fidelity. Mechanistic studies indicate that POT1 facilitates the recruitment of Artemis, which is a nuclease and promotes fidelity of NHEJ, to DNA damage sites. In addition, we found that overexpression of POT1 inhibits the protein stability of Lig3, which is the major regulator of alternative NHEJ (alt-NHEJ), therefore suppressing the efficiency of alt-NHEJ. Taken together we propose that POT1 is a key factor regulating the balance between the efficiency and fidelity of NHEJ at non-telomeric DNA regions.
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Affiliation(s)
- Yang Yu
- Clinical and Translational Research Center of Shanghai First Maternity & Infant Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Science and Technology, Tongji University, Shanghai 200092, China.,State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, China
| | - Rong Tan
- University of Pittsburgh Cancer Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA.,Center for Molecular Medicine, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China
| | - Qian Ren
- Clinical and Translational Research Center of Shanghai First Maternity & Infant Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Science and Technology, Tongji University, Shanghai 200092, China
| | - Boya Gao
- University of Pittsburgh Cancer Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - Zhejin Sheng
- Clinical and Translational Research Center of Shanghai First Maternity & Infant Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Science and Technology, Tongji University, Shanghai 200092, China
| | - Juanlian Zhang
- Clinical and Translational Research Center of Shanghai First Maternity & Infant Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Science and Technology, Tongji University, Shanghai 200092, China
| | - Xiaoqing Zheng
- Clinical and Translational Research Center of Shanghai First Maternity & Infant Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Science and Technology, Tongji University, Shanghai 200092, China
| | - Ying Jiang
- Clinical and Translational Research Center of Shanghai First Maternity & Infant Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Science and Technology, Tongji University, Shanghai 200092, China
| | - Li Lan
- University of Pittsburgh Cancer Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - Zhiyong Mao
- Clinical and Translational Research Center of Shanghai First Maternity & Infant Hospital, Shanghai Key Laboratory of Signaling and Disease Research, School of Life Science and Technology, Tongji University, Shanghai 200092, China.,State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, China
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13
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Harrington L, Pucci F. In medio stat virtus: unanticipated consequences of telomere dysequilibrium. Philos Trans R Soc Lond B Biol Sci 2019; 373:rstb.2016.0444. [PMID: 29335368 PMCID: PMC5784064 DOI: 10.1098/rstb.2016.0444] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/07/2017] [Indexed: 12/13/2022] Open
Abstract
The integrity of chromosome ends, or telomeres, depends on myriad processes that must balance the need to compact and protect the telomeric, G-rich DNA from detection as a double-stranded DNA break, and yet still permit access to enzymes that process, replicate and maintain a sufficient reserve of telomeric DNA. When unable to maintain this equilibrium, erosion of telomeres leads to perturbations at or near the telomeres themselves, including loss of binding by the telomere protective complex, shelterin, and alterations in transcription and post-translational modifications of histones. Although the catastrophic consequences of full telomere de-protection are well described, recent evidence points to other, less obvious perturbations that arise when telomere length equilibrium is altered. For example, critically short telomeres also perturb DNA methylation and histone post-translational modifications at distal sites throughout the genome. In murine stem cells for example, this dysregulated chromatin leads to inappropriate suppression of pluripotency regulator factors such as Nanog. This review summarizes these recent findings, with an emphasis on how these genome-wide, telomere-induced perturbations can have profound consequences on cell function and fate. This article is part of the theme issue ‘Understanding diversity in telomere dynamics’.
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Affiliation(s)
- Lea Harrington
- Wellcome Trust Centre for Cell Biology, School of Biological Sciences, College of Science and Engineering, University of Edinburgh, Mayfield Road, Edinburgh EH9 3JR, UK
| | - Fabio Pucci
- Wellcome Trust Centre for Cell Biology, School of Biological Sciences, College of Science and Engineering, University of Edinburgh, Mayfield Road, Edinburgh EH9 3JR, UK
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14
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Kosebent EG, Uysal F, Ozturk S. Telomere length and telomerase activity during folliculogenesis in mammals. J Reprod Dev 2018; 64:477-484. [PMID: 30270279 PMCID: PMC6305847 DOI: 10.1262/jrd.2018-076] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Telomeres are repetitive non-coding DNA sequences located at the ends of chromosomes in eukaryotic cells. Their most important function is to protect chromosome ends from being recognized
as DNA damage. They are also implicated in meiosis and synapse formation. The length of telomeres inevitably shortens at the end of each round of DNA replication and, also, as a consequence
of the exposure to oxidative stress and/or genotoxic agents. The enzyme telomerase contributes to telomere lengthening. It has been reported that telomerase is exclusively expressed in germ
cells, granulosa cells, early embryos, stem cells, and various types of cancerous cells. Granulosa cells undergo many mitotic divisions and either granulosa cells or oocytes are exposed to a
variety of genotoxic agents throughout folliculogenesis; thus, telomerase plays an important role in the maintenance of telomere length. In this review article, we have comprehensively
evaluated the studies focusing on the regulation of telomerase expression and activity, as well as telomere length, during folliculogenesis from primordial to antral follicles, in several
mammalian species including mice, bovines, and humans. Also, the possible relationships between female infertility caused by follicular development defects and alterations in the telomeres
and/or telomerase activity are discussed.
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Affiliation(s)
- Esra Gozde Kosebent
- Department of Histology and Embryology, Akdeniz University School of Medicine, Antalya 07070, Turkey
| | - Fatma Uysal
- Department of Histology and Embryology, Ankara University School of Medicine, Ankara, Turkey
| | - Saffet Ozturk
- Department of Histology and Embryology, Akdeniz University School of Medicine, Antalya 07070, Turkey
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15
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Effect of oral appliance on circulating leukocyte telomere length and SIRT1 in obstructive sleep apnea. Clin Oral Investig 2018; 23:1397-1405. [DOI: 10.1007/s00784-018-2560-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 07/03/2018] [Indexed: 10/28/2022]
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16
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Smith E, Zhou W, Shindiapina P, Sif S, Li C, Baiocchi RA. Recent advances in targeting protein arginine methyltransferase enzymes in cancer therapy. Expert Opin Ther Targets 2018; 22:527-545. [PMID: 29781349 PMCID: PMC6311705 DOI: 10.1080/14728222.2018.1474203] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
INTRODUCTION Exploration in the field of epigenetics has revealed the diverse roles of the protein arginine methyltransferase (PRMT) family of proteins in multiple disease states. These findings have led to the development of specific inhibitors and discovery of several new classes of drugs with potential to treat both benign and malignant conditions. Areas covered: We provide an overview on the role of PRMT enzymes in healthy and malignant cells, highlighting the role of arginine methylation in specific pathways relevant to cancer pathogenesis. Additionally, we describe structure and catalytic activity of PRMT and discuss the mechanisms of action of novel small molecule inhibitors of specific members of the arginine methyltransferase family. Expert opinion: As the field of PRMT biology advances, it's becoming clear that this class of enzymes is highly relevant to maintaining normal physiologic processes as well and disease pathogenesis. We discuss the potential impact of PRMT inhibitors as a broad class of drugs, including the pleiotropic effects, off target effects the need for more detailed PRMT-centric interactomes, and finally, the potential for targeting this class of enzymes in clinical development of experimental therapeutics for cancer.
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Affiliation(s)
- Emily Smith
- The Division of Hematology, Department of Internal Medicine, The Ohio State University, Columbus, OH 43210, USA
| | - Wei Zhou
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Polina Shindiapina
- The Division of Hematology, Department of Internal Medicine, The Ohio State University, Columbus, OH 43210, USA
| | - Said Sif
- Department of Biological and Environmental Sciences, College of Arts and Sciences, Qatar University, Doha, Qatar
| | - Chenglong Li
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL 32610, USA
- Department of Medicinal Chemistry, College of Pharmacy, University of Florida, Gainesville, FL 32610, USA
| | - Robert A. Baiocchi
- The Division of Hematology, Department of Internal Medicine, The Ohio State University, Columbus, OH 43210, USA
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Huang P, Zhou J, Chen S, Zou C, Zhao X, Li J. The association between obstructive sleep apnea and shortened telomere length: a systematic review and meta-analysis. Sleep Med 2017; 48:107-112. [PMID: 29883927 DOI: 10.1016/j.sleep.2017.09.034] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 09/25/2017] [Accepted: 09/26/2017] [Indexed: 02/07/2023]
Abstract
OBJECTIVE We aimed to provide a more precise estimate of the relationship between telomere length and obstructive sleep apnea (OSA) by systematically reviewing evidence. METHOD We conducted a systematic electronic search in the databases of the PUBMED, PsycINFO, OVID (Medline), EMBASE and other resources (such as Google Scholar). The methodological quality of the articles was assessed according to the Newcastle Ottawa Scale. Heterogeneity was assessed using the chi-square test for Cochrane's Q statistic and I-squared. When heterogeneity was found to be reasonably high between studies, the random-effects model with the mean difference (95% confidence interval [CI]) was conducted using RevMan 5 software by using the inverse variance method (P < 0.05; chi-square test). By contrast, the fixed-effects model was carried out. RESULTS Eight eligible studies involving 2639 participants were included in our meta-analysis. Shortened telomere length was significantly associated with OSA with mean difference of -0.03 (95% CI: -0.06, -0.00; P = 0.003 with I-square of 85%). The results of subgroup analysis preformed by age and sample number suggested that shorter telomere length was significantly associated with OSA, with mean difference of -0.07 (95% CI: -0.07, -0.01; P = 0.005) for adult group and -0.04 (95% CI: -0.02, -0.06; P = 0.005) for large-sample studies. CONCLUSION Compared to healthy people, individuals with OSA have shorter telomere lengths which implicates early intervention and timely treatment for preventing future adverse outcomes.
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Affiliation(s)
- Pan Huang
- Department of Gynecology and Obstetrics, West China Second University Hospital, Sichuan University, Chengdu, Sichuan, People's Republic of China; Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, People's Republic of China
| | - Jianghua Zhou
- Geriatrics Department, Chengdu Fifth People's Hospital, Chengdu, Sichuan, People's Republic of China
| | - Shanping Chen
- Geriatrics Department, Chengdu Fifth People's Hospital, Chengdu, Sichuan, People's Republic of China
| | - Chuan Zou
- Geriatrics Department, Chengdu Fifth People's Hospital, Chengdu, Sichuan, People's Republic of China
| | - Xiufang Zhao
- Department of Gynecology and Obstetrics, West China Second University Hospital, Sichuan University, Chengdu, Sichuan, People's Republic of China; Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, People's Republic of China
| | - Jiping Li
- West China Hospital, Sichuan University, Chengdu, Sichuan, People's Republic of China.
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18
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Hapangama DK, Kamal A, Saretzki G. Implications of telomeres and telomerase in endometrial pathology. Hum Reprod Update 2017; 23:166-187. [PMID: 27979878 PMCID: PMC5850744 DOI: 10.1093/humupd/dmw044] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 12/02/2016] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Eukaryotic chromosomal ends are linear and are protected by nucleoprotein complexes known as telomeres. The complex structural anatomy and the diverse functions of telomeres as well as the unique reverse transcriptase enzyme, telomerase that maintains telomeres are under intensive scientific scrutiny. Both are involved in many human diseases including cancer, but also in ageing and chronic disease such as diabetes. Their intricate involvement in many cellular processes and pathways is being dynamically deciphered in many organs including the endometrium. This review summarizes our current knowledge on the topic of telomeres and telomerase and their potential role in providing plausible explanations for endometrial aberrations related to common gynaecological pathologies. OBJECTIVE AND RATIONALE This review outlines the recent major findings in telomere and telomerase functions in the context of endometrial biology. It highlights the contemporary discoveries in hormonal regulation, normal endometrial regeneration, stem cells and common gynaecological diseases such as endometriosis, infertility, recurrent reproductive failure and endometrial cancer (EC). SEARCH METHODS The authors carried out systematic PubMed (Medline) and Ovid searches using the key words: telomerase, telomeres, telomere length, human telomerase reverse transcriptase, telomeric RNA component, with endometrium, hormonal regulation, endometrial stem/progenitor cells, endometrial regeneration, endometriosis, recurrent miscarriage, infertility, endometrial hyperplasia, EC and uterine cancer. Publications used in this review date from 1995 until 31st June 2016. OUTCOMES The human endometrium is a unique somatic organ, which displays dynamic telomerase activity (TA) related to the menstrual cycle. Telomerase is implicated in almost all endometrial pathologies and appears to be crucial to endometrial stem cells. In particular, it is vital for normal endometrial regeneration, providing a distinct route to formulate possible curative, non-hormonal therapies to treat chronic endometrial conditions. Furthermore, our current understanding of telomere maintenance in EC is incomplete. Data derived from other malignancies on the role of telomerase in carcinogenesis cannot be extrapolated to EC because unlike in other cancers, TA is already present in proliferating healthy endometrial cells. WIDER IMPLICATIONS Since telomerase is pivotal to endometrial regeneration, further studies elucidating the role of telomeres, telomerase, their associated proteins and their regulation in normal endometrial regeneration as well as their role in endometrial pathologies are essential. This approach may allow future development of novel treatment strategies that are not only non-hormonal but also potentially curative.
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Affiliation(s)
- D K Hapangama
- Department of Women's and Children's Health, Institute of Translational Medicine, University of Liverpool, Liverpool, L8 7SS, UK.,Liverpool Women's Hospital NHS Foundation Trust, Crown Street, Liverpool L8 7SS, UK
| | - A Kamal
- Department of Women's and Children's Health, Institute of Translational Medicine, University of Liverpool, Liverpool, L8 7SS, UK.,The National Center for Early Detection of Cancer, Oncology Teaching Hospital, Baghdad Medical City, Baghdad, Iraq
| | - G Saretzki
- Institute for Ageing and Institute for Cell and Molecular Biosciences, Campus for Ageing and Vitality, Newcastle University, Newcastle upon Tyne, NE4 5PL, UK
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19
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Liu B, Yan R, Zhang J, Wang B, Sun H, Cui X. Abnormal mRNA Expression Levels of Telomere-Binding Proteins Represent Biomarkers in Myelodysplastic Syndromes: A Case-Control Study. Turk J Haematol 2017; 34:200-206. [PMID: 28404540 PMCID: PMC5544038 DOI: 10.4274/tjh.2016.0364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Objective: As evidence was shown that abnormal shortening of telomeres begins to accumulate in myelodysplastic syndrome (MDS) patients, this study was conducted to determine the relationship between the mRNA expression levels of telomere-binding proteins (TRF1/TRF2/TIN2/TPP1/POT1/RAP1) and the risk level in MDS. Materials and Methods: There were 40 patients with MDS and 40 normal controls in this study. Methods including telomere content assays and quantitative reverse transcription-polymerase chain reaction were used to examine the mRNA levels of TRF1/TRF2/TIN2/TPP1/POT1/RAP1 in patients with MDS. Results: Compared to the normal group used as a control, the mRNA expression levels of RAP1/POT1/TPP1 of the patients with MDS were decreased, whereas their levels of TRF1/TRF2 and TIN2 were increased. A positive correlation was found between the TRF1, TRF2, and TIN2 mRNA expression levels and the risk level of the International Prognostic Scoring System (IPSS) and the World Health Organization Prognostic Scoring System (WPSS) criteria; however, a negative correlation was found between RAP1/POT1/TPP1 mRNA expression levels and the risk levels of IPSS and WPSS criteria. Conclusion: Because the reduction of TRF1/TRF2/TIN2 mRNA expression and the increase of RAP1/POT1/TPP1 mRNA expression are closely related to the risk levels of the IPSS and WPSS criteria in MDS, it is thought that these telomere-binding proteins could lead to abnormal telomere length and function, which cause chromosomal abnormalities in MDS. With this evidence, we suggest that those proteins’ mRNA expressions could be used as biomarkers for the assessment of the risk degree of MDS patients.
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Affiliation(s)
| | | | | | | | | | - Xing Cui
- Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Department of Hematology, Jinan, China
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20
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Musumeci D, Amato J, Zizza P, Platella C, Cosconati S, Cingolani C, Biroccio A, Novellino E, Randazzo A, Giancola C, Pagano B, Montesarchio D. Tandem application of ligand-based virtual screening and G4-OAS assay to identify novel G-quadruplex-targeting chemotypes. Biochim Biophys Acta Gen Subj 2017; 1861:1341-1352. [PMID: 28130159 DOI: 10.1016/j.bbagen.2017.01.024] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2016] [Revised: 01/16/2017] [Accepted: 01/23/2017] [Indexed: 11/29/2022]
Abstract
BACKGROUND G-quadruplex (G4) structures are key elements in the regulation of cancer cell proliferation and their targeting is deemed to be a promising strategy in anticancer therapy. METHODS A tandem application of ligand-based virtual screening (VS) calculations together with the experimental G-quadruplex on Oligo Affinity Support (G4-OAS) assay was employed to discover novel G4-targeting compounds. The interaction of the selected compounds with the investigated G4 in solution was analysed through a series of biophysical techniques and their biological activity investigated by immunofluorescence and MTT assays. RESULTS A focused library of 60 small molecules, designed as putative G4 groove binders, was identified through the VS. The G4-OAS experimental screening led to the selection of 7 ligands effectively interacting with the G4-forming human telomeric DNA. Evaluation of the biological activity of the selected compounds showed that 3 ligands of this sub-library induced a marked telomere-localized DNA damage response in human tumour cells. CONCLUSIONS The combined application of virtual and experimental screening tools proved to be a successful strategy to identify new bioactive chemotypes able to target the telomeric G4 DNA. These compounds may represent useful leads for the development of more potent and selective G4 ligands. GENERAL SIGNIFICANCE Expanding the repertoire of the available G4-targeting chemotypes with improved physico-chemical features, in particular aiming at the discovery of novel, selective G4 telomeric ligands, can help in developing effective anti-cancer drugs with fewer side effects. This article is part of a Special Issue entitled "G-quadruplex" Guest Editor: Dr. Concetta Giancola and Dr. Daniela Montesarchio.
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Affiliation(s)
- Domenica Musumeci
- Department of Chemical Sciences, University of Naples Federico II, Naples 80126, Italy
| | - Jussara Amato
- Department of Pharmacy, University of Naples Federico II, Naples 80131, Italy
| | - Pasquale Zizza
- Oncogenomic and Epigenetic Unit, Regina Elena National Cancer Institute, Rome 00144, Italy
| | - Chiara Platella
- Department of Chemical Sciences, University of Naples Federico II, Naples 80126, Italy
| | | | - Chiara Cingolani
- Oncogenomic and Epigenetic Unit, Regina Elena National Cancer Institute, Rome 00144, Italy
| | - Annamaria Biroccio
- Oncogenomic and Epigenetic Unit, Regina Elena National Cancer Institute, Rome 00144, Italy
| | - Ettore Novellino
- Department of Pharmacy, University of Naples Federico II, Naples 80131, Italy
| | - Antonio Randazzo
- Department of Pharmacy, University of Naples Federico II, Naples 80131, Italy
| | - Concetta Giancola
- Department of Pharmacy, University of Naples Federico II, Naples 80131, Italy
| | - Bruno Pagano
- Department of Pharmacy, University of Naples Federico II, Naples 80131, Italy.
| | - Daniela Montesarchio
- Department of Chemical Sciences, University of Naples Federico II, Naples 80126, Italy.
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Mattern F, Herrmann D, Heinzmann J, Hadeler KG, Bernal-Ulloa SM, Haaf T, Niemann H. DNA methylation and mRNA expression of developmentally important genes in bovine oocytes collected from donors of different age categories. Mol Reprod Dev 2016; 83:802-814. [PMID: 27567027 DOI: 10.1002/mrd.22692] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 08/23/2016] [Indexed: 12/26/2022]
Abstract
Epigenetic changes are critical for the acquisition of developmental potential by oocytes and embryos, yet these changes may be sensitive to maternal ageing. Here, we investigated the impact of maternal ageing on DNA methylation and mRNA expression in a panel of eight genes that are critically involved in oocyte and embryo development. Bovine oocytes were collected from donors of three different age categories-prepubertal (9-12 months old), mature (3-7 years old), and aged (8-11 years old)-and were analyzed for gene-specific DNA methylation (bTERF2, bREC8, bBCL-XL, bPISD, bBUB1, bDNMT3Lo, bH19, and bSNRPN) and mRNA expression (bTERF2, bBCL-XL, bPISD, and bBUB1). A total of 1,044 alleles with 88,740 CpGs were amplified and sequenced from 362 bovine oocytes. Most of the detected molecules were either fully methylated or completely unmethylated. Only 9 out of 1,044 alleles (<1%) were abnormally methylated (>50% of CpGs with an aberrant methylation status), and seven of the nine abnormally methylated alleles were within only two candidate genes (bDNMT3Lo and bH19). No significant differences were detected with regard to mRNA expression between oocytes from the three groups of donors. These results suggest that genes predominantly important for early embryo development (bH19 and bDNMT3Lo) are less resistant to abnormal methylation than genes critically involved in oocyte development (bTERF2, bBCL-XL, bPISD, bBUB1, and bSNRPN). Establishment of DNA methylation in bovine oocytes seems to be largely resistant to changes caused by maternal ageing, irrespective of whether the genes are critical to achieve developmental competence in oocytes or early embryos. Mol. Reprod. Dev. 83: 802-814, 2016 © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Felix Mattern
- Institute of Human Genetics, Julius Maximilians University, Würzburg, Germany
| | - Doris Herrmann
- Institute of Farm Animal Genetics (FLI), Mariensee, Neustadt, Germany
| | - Julia Heinzmann
- Institute of Farm Animal Genetics (FLI), Mariensee, Neustadt, Germany
| | | | | | - Thomas Haaf
- Institute of Human Genetics, Julius Maximilians University, Würzburg, Germany
| | - Heiner Niemann
- Institute of Farm Animal Genetics (FLI), Mariensee, Neustadt, Germany.
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Boskovic J, Martinez-Gago J, Mendez-Pertuz M, Buscato A, Martinez-Torrecuadrada JL, Blasco MA. Molecular Architecture of Full-length TRF1 Favors Its Interaction with DNA. J Biol Chem 2016; 291:21829-21835. [PMID: 27563064 DOI: 10.1074/jbc.m116.744896] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 08/23/2016] [Indexed: 11/06/2022] Open
Abstract
Telomeres are specific DNA-protein structures found at both ends of eukaryotic chromosomes that protect the genome from degradation and from being recognized as double-stranded breaks. In vertebrates, telomeres are composed of tandem repeats of the TTAGGG sequence that are bound by a six-subunit complex called shelterin. Molecular mechanisms of telomere functions remain unknown in large part due to lack of structural data on shelterins, shelterin complex, and its interaction with the telomeric DNA repeats. TRF1 is one of the best studied shelterin components; however, the molecular architecture of the full-length protein remains unknown. We have used single-particle electron microscopy to elucidate the structure of TRF1 and its interaction with telomeric DNA sequence. Our results demonstrate that full-length TRF1 presents a molecular architecture that assists its interaction with telometic DNA and at the same time makes TRFH domains accessible to other TRF1 binding partners. Furthermore, our studies suggest hypothetical models on how other proteins as TIN2 and tankyrase contribute to regulate TRF1 function.
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Affiliation(s)
- Jasminka Boskovic
- From the Structural Biology and Biocomputing Programme, Electron Microscopy Unit,
| | - Jaime Martinez-Gago
- Structural Biology and Biocomputing Programme, Crystallography and Protein Engineering Unit, and
| | - Marinela Mendez-Pertuz
- Molecular Oncology Programme, Telomeres and Telomerase Group, Spanish National Cancer Research Centre (CNIO), 28029 Madrid, Spain
| | - Alberto Buscato
- From the Structural Biology and Biocomputing Programme, Electron Microscopy Unit
| | | | - Maria A Blasco
- Molecular Oncology Programme, Telomeres and Telomerase Group, Spanish National Cancer Research Centre (CNIO), 28029 Madrid, Spain
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Liu Q, Sun Y, Lv Y, Le Z, Xin Y, Zhang P, Liu Y. TERT alleviates irradiation-induced late rectal injury by reducing hypoxia-induced ROS levels through the activation of NF-κB and autophagy. Int J Mol Med 2016; 38:785-93. [PMID: 27431814 PMCID: PMC4990283 DOI: 10.3892/ijmm.2016.2673] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Accepted: 06/28/2016] [Indexed: 12/11/2022] Open
Abstract
The hypoxic microenvironment which is present following irradiation has been proven to promote radiation-induced injury to normal tissues. Previous studies have demonstrated that telomerase reverse transcriptase (TERT) is regulated by hypoxia, and that it plays a protective role in the process of wound repair. However, its effects on radiation-induced injury remain unclear. In this study, we examined the effects of human TERT on irradiation-induced late rectal injury in fibroblasts under hypoxic conditions. We also performed in vivo experiments. The rectums of 5-week-old female C57BL/6N mice were irradiated locally with a single dose of 25 Gy. We then examined the fibrotic changes using hematoxylin and eosin staining, and Masson's staining. The expression of hypoxia inducible factor-1α (HIF-1α) and TERT was analyzed by immunohistochemistry. In in vitro experiments, apoptosis, reactive oxygen species (ROS) production and the autophagy level induced by exposure to hypoxia were assayed in fibroblasts. The association between TERT, nuclear factor-κB (NF-κB) and the autophagy level was examined by western blot analysis. The antioxidant effects of TERT were examined on the basis of the ratio of glutathione to glutathione disulfide (GSH/GSSG) and mitochondrial membrane potential. Rectal fibrosis was induced significantly at 12 weeks following irradiation. The HIF-1α and TERT expression levels increased in the fibrotic region. The TERT-overexpressing fibroblasts (transfected with an hTERT-expressing lentiviral vector) exhibited reduced apoptosis, reduced ROS production, a higher autophagy level, a higher GSH/GSSG ratio and stable mitochondrial membrane potential compared with the fibroblasts in which TERT had been silenced by siRNA. NF-κB was activated by TERT, and the inhibition of TERT reduced the autophagy level in the fibroblasts. These results demonstrate that TERT decreases cellular ROS production, while maintaining mitochondrial function and protecting the cells from hypoxia-induced apoptosis, which may thus attenuate the effects of irradiation-induced hypoxia on rectal injury following irradiation.
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Affiliation(s)
- Qi Liu
- Cancer Research Institute, Fudan University Shanghai Cancer Center, Shanghai 200032, P.R. China
| | - Yong Sun
- Cancer Research Institute, Fudan University Shanghai Cancer Center, Shanghai 200032, P.R. China
| | - Yuefeng Lv
- Department of Obstetrics, Shiyan Taihe Hospital, Hubei University of Medcine, Shiyan, Hubei 442000, P.R. China
| | - Ziyu Le
- Department of Radiation Oncology, Fudan University Shanghai Cancer Center, Shanghai 200032, P.R. China
| | - Yuhu Xin
- Cancer Research Institute, Fudan University Shanghai Cancer Center, Shanghai 200032, P.R. China
| | - Ping Zhang
- Cancer Research Institute, Fudan University Shanghai Cancer Center, Shanghai 200032, P.R. China
| | - Yong Liu
- Cancer Research Institute, Fudan University Shanghai Cancer Center, Shanghai 200032, P.R. China
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Aminizadeh N, Tiraihi T, Mesbah-Namin SA, Taheri T. Stimulation of cell proliferation by glutathione monoethyl ester in aged bone marrow stromal cells is associated with the assistance of TERT gene expression and telomerase activity. In Vitro Cell Dev Biol Anim 2016; 52:772-81. [DOI: 10.1007/s11626-016-0021-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Accepted: 03/23/2016] [Indexed: 01/08/2023]
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25
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Li B, Qiao R, Wang Z, Zhou W, Li X, Xu W, Rao Z. Crystal structure of a tankyrase 1-telomere repeat factor 1 complex. Acta Crystallogr F Struct Biol Commun 2016; 72:320-7. [PMID: 27050267 PMCID: PMC4822990 DOI: 10.1107/s2053230x16004131] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 03/11/2016] [Indexed: 12/13/2022] Open
Abstract
Telomere repeat factor 1 (TRF1) is a subunit of shelterin (also known as the telosome) and plays a critical role in inhibiting telomere elongation by telomerase. Tankyrase 1 (TNKS1) is a poly(ADP-ribose) polymerase that regulates the activity of TRF1 through poly(ADP-ribosyl)ation (PARylation). PARylation of TRF1 by TNKS1 leads to the release of TRF1 from telomeres and allows telomerase to access telomeres. The interaction between TRF1 and TNKS1 is thus important for telomere stability and the mitotic cell cycle. Here, the crystal structure of a complex between the N-terminal acidic domain of TRF1 (residues 1-55) and a fragment of TNKS1 covering the second and third ankyrin-repeat clusters (ARC2-3) is presented at 2.2 Å resolution. The TNKS1-TRF1 complex crystals were optimized using an `oriented rescreening' strategy, in which the initial crystallization condition was used as a guide for a second round of large-scale sparse-matrix screening. This crystallographic and biochemical analysis provides a better understanding of the TRF1-TNKS1 interaction and the three-dimensional structure of the ankyrin-repeat domain of TNKS.
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Affiliation(s)
- Bo Li
- College of Life Sciences, Nankai University, Weijin Road #94, Tianjin 300071, People’s Republic of China
| | - Ruihong Qiao
- College of Life Sciences, Nankai University, Weijin Road #94, Tianjin 300071, People’s Republic of China
| | - Zhizhi Wang
- Department of Biological Structure, University of Washington, 1959 NE Pacific Street, Seattle, Washington 98195, USA
| | - Weihong Zhou
- College of Life Sciences, Nankai University, Weijin Road #94, Tianjin 300071, People’s Republic of China
| | - Xin Li
- College of Life Sciences, Nankai University, Weijin Road #94, Tianjin 300071, People’s Republic of China
| | - Wenqing Xu
- Department of Biological Structure, University of Washington, 1959 NE Pacific Street, Seattle, Washington 98195, USA
| | - Zihe Rao
- College of Life Sciences, Nankai University, Weijin Road #94, Tianjin 300071, People’s Republic of China
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Essential role of the Cdk2 activator RingoA in meiotic telomere tethering to the nuclear envelope. Nat Commun 2016; 7:11084. [PMID: 27025256 PMCID: PMC4820962 DOI: 10.1038/ncomms11084] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Accepted: 02/19/2016] [Indexed: 11/24/2022] Open
Abstract
Cyclin-dependent kinases (CDKs) play key roles in cell cycle regulation. Genetic analysis in mice has revealed an essential role for Cdk2 in meiosis, which renders Cdk2 knockout (KO) mice sterile. Here we show that mice deficient in RingoA, an atypical activator of Cdk1 and Cdk2 that has no amino acid sequence homology to cyclins, are sterile and display meiotic defects virtually identical to those observed in Cdk2 KO mice including non-homologous chromosome pairing, unrepaired double-strand breaks, undetectable sex-body and pachytene arrest. Interestingly, RingoA is required for Cdk2 targeting to telomeres and RingoA KO spermatocytes display severely affected telomere tethering as well as impaired distribution of Sun1, a protein essential for the attachment of telomeres to the nuclear envelope. Our results identify RingoA as an important activator of Cdk2 at meiotic telomeres, and provide genetic evidence for a physiological function of mammalian Cdk2 that is not dependent on cyclins. CDKs play central roles in cell cycle regulation and are normally activated by cyclins. Here the authors show that RingoA induces a cyclin-independent function of CDK2 at meiotic telomeres, which regulates their tethering to the nuclear envelope and proper synapsis of homologous chromosomes.
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Altieri P, Barisione C, Lazzarini E, Garuti A, Bezante GP, Canepa M, Spallarossa P, Tocchetti CG, Bollini S, Brunelli C, Ameri P. Testosterone Antagonizes Doxorubicin-Induced Senescence of Cardiomyocytes. J Am Heart Assoc 2016; 5:JAHA.115.002383. [PMID: 26746999 PMCID: PMC4859360 DOI: 10.1161/jaha.115.002383] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Background Chronic cardiotoxicity is less common in male than in female patients receiving doxorubicin and other anthracyclines at puberty and adolescence. We hypothesized that this sex difference might be secondary to distinct activities of sex hormones on cardiomyocyte senescence, which is thought to be central to the development of long‐term anthracycline cardiomyopathy. Methods and Results H9c2 cells and neonatal mouse cardiomyocytes were exposed to doxorubicin with or without prior incubation with testosterone or 17β‐estradiol, the main androgen and estrogen, respectively. Testosterone, but not 17β‐estradiol, counteracted doxorubicin‐elicited senescence. Downregulation of telomere binding factor 2, which has been pinpointed previously as being pivotal to doxorubicin‐induced senescence, was also prevented by testosterone, as were p53 phosphorylation and accumulation. Pretreatment with the androgen receptor antagonist flutamide, the phosphatidylinositol 3 kinase inhibitor LY294002, and the nitric oxide synthase inhibitor L‐NG‐nitroarginine methyl ester abrogated the reduction in senescence and the normalization of telomere binding factor 2 levels attained by testosterone. Consistently, testosterone enhanced the phosphorylation of AKT and nitric oxide synthase 3. In H9c2 cells, doxorubicin‐stimulated senescence was still observed up to 21 days after treatment and increased further when cells were rechallenged with doxorubicin 14 days after the first exposure to mimic the schedule of anthracycline‐containing chemotherapy. Remarkably, these effects were also inhibited by testosterone. Conclusions Testosterone protects cardiomyocytes against senescence caused by doxorubicin at least in part by modulating telomere binding factor 2 via a pathway involving the androgen receptor, phosphatidylinositol 3 kinase, AKT, and nitric oxide synthase 3. This is a potential mechanism by which pubescent and adolescent boys are less prone to chronic anthracycline cardiotoxicity than girls.
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Affiliation(s)
- Paola Altieri
- Laboratory of Cardiovascular BiologyDepartment of Internal MedicineUniversity of GenovaItaly
| | - Chiara Barisione
- Laboratory of Cardiovascular BiologyDepartment of Internal MedicineUniversity of GenovaItaly
| | - Edoardo Lazzarini
- Laboratory of Cardiovascular BiologyDepartment of Internal MedicineUniversity of GenovaItaly
| | - Anna Garuti
- Laboratory of Cellular TherapiesDepartment of Internal MedicineUniversity of GenovaItaly
| | - Gian Paolo Bezante
- Laboratory of Cardiovascular BiologyDepartment of Internal MedicineUniversity of GenovaItaly
| | - Marco Canepa
- Laboratory of Cardiovascular BiologyDepartment of Internal MedicineUniversity of GenovaItaly
| | - Paolo Spallarossa
- Laboratory of Cardiovascular BiologyDepartment of Internal MedicineUniversity of GenovaItaly
| | - Carlo Gabriele Tocchetti
- Division of Internal MedicineDepartment of Translational Medical SciencesFederico II UniversityNapoliItaly
| | - Sveva Bollini
- Regenerative Medicine LaboratoryDepartment of Experimental MedicineUniversity of GenovaItaly
| | - Claudio Brunelli
- Laboratory of Cardiovascular BiologyDepartment of Internal MedicineUniversity of GenovaItaly
| | - Pietro Ameri
- Laboratory of Cardiovascular BiologyDepartment of Internal MedicineUniversity of GenovaItaly
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Carkic J, Nikolic N, Radojevic-Skodric S, Kuzmanovic-Pficer J, Brajovic G, Antunovic M, Milasin J, Popovic B. The role of TERT-CLPTM1L SNPs, hTERT expression and telomere length in the pathogenesis of oral squamous cell carcinoma. J Oral Sci 2016; 58:449-458. [DOI: 10.2334/josnusd.16-0108] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
Affiliation(s)
- Jelena Carkic
- Institute of Human Genetics, School of Dental Medicine, University of Belgrade
| | - Nadja Nikolic
- Institute of Human Genetics, School of Dental Medicine, University of Belgrade
| | | | - Jovana Kuzmanovic-Pficer
- Department for Medical Statistics and Informatics, School of Dental Medicine, University of Belgrade
| | - Gavrilo Brajovic
- Department of Physiology, School of Dental Medicine, University of Belgrade
| | - Marija Antunovic
- Clinic of Oral Surgery, School of Medicine, University of Montenegro
| | - Jelena Milasin
- Institute of Human Genetics, School of Dental Medicine, University of Belgrade
| | - Branka Popovic
- Institute of Human Genetics, School of Dental Medicine, University of Belgrade
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Gu C, Li Q, Zhu Y, Qu Y, Zhang G, Wang M, Yang Y, Wang J, Jin L, Wei Q, Ye D. Genetic variants in the TEP1 gene are associated with prostate cancer risk and recurrence. Prostate Cancer Prostatic Dis 2015; 18:310-6. [DOI: 10.1038/pcan.2015.27] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Revised: 04/08/2015] [Accepted: 04/13/2015] [Indexed: 02/06/2023]
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Deeb D, Gao X, Liu Y, Pindolia K, Gautam SC. Inhibition of hTERT/telomerase contributes to the antitumor activity of pristimerin in pancreatic ductal adenocarcinoma cells. Oncol Rep 2015; 34:518-24. [PMID: 25997419 PMCID: PMC4484616 DOI: 10.3892/or.2015.3989] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 04/14/2015] [Indexed: 02/06/2023] Open
Abstract
Pristimerin (PM) is a promising anticancer agent that has exhibited strong antiproliferative and apoptosis-inducing activity in various types of cancer cells. In the present study, we investigated the role of telomerase in mediating the antitumor activity of PM in pancreatic ductal adenocarcinoma (PDA) cells. PM inhibited cell proliferation, arrested cells in the G1 cell cycle phase and induced apoptosis in MiaPaCa-2 and Panc-1 PDA cells. These antitumor activities of PM correlated well with the inhibition of human telomerase reverse transcriptase (hTERT), the gene that codes for the catalytic subunit of telomerase complex. Gene knockin and knockdown approaches demonstrated that hTERT regulates the response of PDA cells to PM. PM inhibited hTERT expression by suppressing the transcription factors Sp1, c-Myc and NF-κB which control hTERT gene expression. PM also inhibited protein kinase Akt, which phosphorylates and facilitates hTERT nuclear importation and its telomerase activity. These findings identified hTERT (telomerase) as a potential therapeutic target of PM for the treatment of PDA.
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Affiliation(s)
- Dorrah Deeb
- Department of Surgery, Henry Ford Health System, Detroit, MI 48202, USA
| | - Xiaohua Gao
- Department of Surgery, Henry Ford Health System, Detroit, MI 48202, USA
| | - Yongbo Liu
- Department of Surgery, Henry Ford Health System, Detroit, MI 48202, USA
| | - Kirit Pindolia
- Department of Research, Henry Ford Health System, Detroit, MI 48202, USA
| | - Subhash C Gautam
- Department of Surgery, Henry Ford Health System, Detroit, MI 48202, USA
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Aredia F, Scovassi AI. Poly(ADP-ribose): a signaling molecule in different paradigms of cell death. Biochem Pharmacol 2014; 92:157-63. [PMID: 24976506 DOI: 10.1016/j.bcp.2014.06.021] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Revised: 06/17/2014] [Accepted: 06/17/2014] [Indexed: 12/11/2022]
Abstract
Poly(ADP-ribosylation) results from the conversion of NAD(+) into ADP-ribose and the following addition of ADP-ribose units to form polymers, further bound to acceptor proteins; once post-translationally ADP-ribosylated, proteins could change their function in basic processes. Poly(ADP-ribosylation) is activated under critical situations represented by DNA damage and cellular stress, and modulated in different paradigms of cell death. The hallmarks of the main death processes, i.e. apoptosis, parthanatos, necroptosis and autophagy, will be described, focusing on the role of poly(ADP-ribose) as a signaling molecule.
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Affiliation(s)
- Francesca Aredia
- Istituto di Genetica Molecolare CNR, Via Abbiategrasso 207, 27100 Pavia, Italy
| | - Anna Ivana Scovassi
- Istituto di Genetica Molecolare CNR, Via Abbiategrasso 207, 27100 Pavia, Italy.
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Salpea KD, Maubaret CG, Kathagen A, Ken-Dror G, Gilroy DW, Humphries SE. The effect of pro-inflammatory conditioning and/or high glucose on telomere shortening of aging fibroblasts. PLoS One 2013; 8:e73756. [PMID: 24086293 PMCID: PMC3781104 DOI: 10.1371/journal.pone.0073756] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Accepted: 07/30/2013] [Indexed: 01/29/2023] Open
Abstract
UNLABELLED Cardiovascular disease and diabetes have been linked to shorter telomeres, but it is not yet clear which risk factors contribute to shorter telomeres in patients. Our aim was to examine whether pro-inflammatory conditioning, in combination or not with high glucose, result in a higher rate of telomere shortening during in vitro cellular ageing. Human fibroblasts from four donors were cultured for 90 days in: 1) medium lacking ascorbic acid only, 2) 10 mM buthionine sulphoximine (BSO) (pro-oxidant), 3) 25 mM D-glucose, 4) 1 ng/ml IL1B and 5) 25 mM D-glucose+1 ng/ml IL1B. Telomere length was measured with qPCR and intracellular reactive oxygen species (ROS) content and cell death with flow cytometry. Cultures treated with high glucose and BSO displayed a significantly lower growth rate, and cultures treated with IL1B showed a trend towards a higher growth rate, compared to the control [Glucose:0.14 PD/day, p<0.001, BSO: 0.11 PD/day, p = 0.006 and IL1B: 0.19 PD/day, p = 0.093 vs. CONTROL 0.16 PD/day]. Telomere shortening with time was significantly accelerated in cultures treated with IL1B compared to the control [IL1B:-0.8%/day (95%CI:-1.1, -0.5) vs. CONTROL -0.6%/day (95%CI:-0.8, -0.3), p = 0.012]. The hastening of telomere shortening by IL1B was only in part attenuated after adjustment for the number of cell divisions [IL1B:-4.1%/PD (95%CI:-5.7, -2.4) vs. CONTROL -2.5%/PD (95%CI:-4.4, -0.7), p = 0.067]. The intracellular ROS content displayed 69% increase (p = 0.033) in BSO compared to the control. In aging fibroblasts, pro-inflammatory conditioning aggravates the shortening of telomeres, an effect which was only in part driven by increased cell turnover. High glucose alone did not result in greater production of ROS or telomere shortening.
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Affiliation(s)
- Klelia D. Salpea
- Centre for Cardiovascular Genetics, Division of Medicine, University College London, London, United Kingdom
- * E-mail: (KDS); (CGM)
| | - Cecilia G. Maubaret
- Centre for Cardiovascular Genetics, Division of Medicine, University College London, London, United Kingdom
- * E-mail: (KDS); (CGM)
| | - Annegret Kathagen
- Centre for Cardiovascular Genetics, Division of Medicine, University College London, London, United Kingdom
| | - Gie Ken-Dror
- Centre for Cardiovascular Genetics, Division of Medicine, University College London, London, United Kingdom
| | - Derek W. Gilroy
- Centre for Clinical Pharmacology and Therapeutics, Division of Medicine, University College London, London, United Kingdom
| | - Steve E. Humphries
- Centre for Cardiovascular Genetics, Division of Medicine, University College London, London, United Kingdom
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Gómez DLM, Farina HG, Gómez DE. Telomerase regulation: a key to inhibition? (Review). Int J Oncol 2013; 43:1351-6. [PMID: 24042470 DOI: 10.3892/ijo.2013.2104] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2013] [Accepted: 07/05/2013] [Indexed: 11/06/2022] Open
Abstract
Telomerase has been recognized as a common factor in most tumor cells, and in turn a distinctive feature with respect to non-malignant cells. This feature has made telomerase a promising target for cancer therapy. Telomerase studies revealed that it is a multi-subunit complex possessing different levels of regulation, including control of expression, phosphorylation state, assembly and transportation to sites of activity. Thus, we emphasize that targeting telomerase expression or activity is not the only way to shorten telomeres, induce cell senescence and apoptosis. Therefore, there are multiple sites capable of allowing the modulation of its enzymatic activity. In the development of strategies based on the regulation of telomerase activity the understanding of the mechanisms regulating their subunits is essential. Based on this, in this review we summarize the current state of knowledge of some regulatory mechanisms of the components of the telomerase complex, and hypothetize their potential therapeutic application against cancer.
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Affiliation(s)
- Diego L Mengual Gómez
- Laboratory of Molecular Oncology, Science and Technology Department, National University of Quilmes, Buenos Aires, Argentina
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Ozturk S, Sozen B, Demir N. Telomere length and telomerase activity during oocyte maturation and early embryo development in mammalian species. Mol Hum Reprod 2013; 20:15-30. [DOI: 10.1093/molehr/gat055] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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Tenga MJ, Lazar IM. Proteomic snapshot of breast cancer cell cycle: G1/S transition point. Proteomics 2013; 13:48-60. [PMID: 23152136 DOI: 10.1002/pmic.201200188] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2012] [Revised: 09/22/2012] [Accepted: 10/25/2012] [Indexed: 01/16/2023]
Abstract
The biological processes that unfold during the G1-phase of the cell cycle are dependent on extracellular mitogenic factors that signal the cell to enter a state of quiescence, or commit to a cell-cycle round by passing the restriction point (R-point) and enter the S-phase. Unlike normal cells, cancer cells evolved the ability to evade the R-point and continue through the cell cycle even in the presence of extensive DNA damage or absence of mitogenic signals. The purpose of this study was to perform a quantitative proteomic evaluation of the biological processes that are responsible for driving MCF-7 breast cancer cells into division even when molecular checkpoints such as the G1/S R-point are in place. Nuclear and cytoplasmic fractions of the G1 and S cell-cycle phases were analyzed by LC-MS/MS to result in the confident identification of more than 2700 proteins. Statistical evaluation of the normalized data resulted in the selection of proteins that displayed twofold or more change in spectral counts in each cell state. Pathway mapping, functional annotation clustering, and protein interaction network analysis revealed that the top-scoring clusters that could play a role in overriding the G1/S transition point included DNA damage response, chromatin remodeling, transcription/translation regulation, and signaling proteins.
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Affiliation(s)
- Milagros J Tenga
- Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 246021, USA
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Wang C, Xiao H, Ma J, Zhu Y, Yu J, Sun L, Sun H, Liu Y, Jin C, Huang H. The F-box protein β-TrCP promotes ubiquitination of TRF1 and regulates the ALT-associated PML bodies formation in U2OS cells. Biochem Biophys Res Commun 2013; 434:728-34. [DOI: 10.1016/j.bbrc.2013.03.096] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Accepted: 03/26/2013] [Indexed: 10/26/2022]
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Deeb D, Gao X, Liu Y, Varma NRS, Arbab AS, Gautam SC. Inhibition of telomerase activity by oleanane triterpenoid CDDO-Me in pancreatic cancer cells is ROS-dependent. Molecules 2013; 18:3250-65. [PMID: 23486104 PMCID: PMC3632053 DOI: 10.3390/molecules18033250] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 02/27/2013] [Accepted: 03/06/2013] [Indexed: 12/12/2022] Open
Abstract
Methyl-2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oate (CDDO-Me) is a synthetic derivative of oleanolic acid, a triterpene, with apoptosis-inducing activity in a wide range of cancer cells. Induction of apoptosis by CDDO-Me is associated with the generation of reactive oxygen species (ROS) and inhibition of telomerase activity. In the present study, we investigated the role of ROS in inhibition of telomerase by CDDO-me. Treatment of MiaPaCa-2 and Panc-1 pancreatic cancer cell lines with CDDO-Me induced the production of hydrogen peroxide and superoxide anions and inhibited the telomerase activity. Pretreatment of cells with N-acetylcycsteine, a general purpose antioxidant or overexpression of glutathione peroxidase (GPx) or superoxide dismutase-1 (SOD-1) blocked the telomerase inhibitory activity of CDDO-Me. Furthermore, blocking ROS generation also prevented the inhibition of hTERT gene expression, hTERT protein production and expression of a number of hTERT-regulatory proteins by CDDO-Me (e.g., c-Myc, Sp1, NF-κB and p-Akt). Data also showed that Akt plays an important role in the activation of telomerase activity. Together, these data suggest that inhibition of telomerase activity by CDDO-Me is mediated through a ROS-dependent mechanism; however, more work is needed to fully understand the role of ROS in down-regulation of hTERT gene and hTERT-regulatory proteins by CDDO-Me.
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Affiliation(s)
- Dorrah Deeb
- Department of General Surgery, Henry Ford Health System, Detroit, MI 48202, USA; E-Mails: (D.D.); (X.G.); (Y.L.)
| | - Xiaohua Gao
- Department of General Surgery, Henry Ford Health System, Detroit, MI 48202, USA; E-Mails: (D.D.); (X.G.); (Y.L.)
| | - Yongbo Liu
- Department of General Surgery, Henry Ford Health System, Detroit, MI 48202, USA; E-Mails: (D.D.); (X.G.); (Y.L.)
| | - Nadimpalli R. S. Varma
- Department of Radiology Research, Henry Ford Health System, Detroit, MI 48202, USA; E-Mails: (N.R.S.V.); (A.S.A.)
| | - Ali S. Arbab
- Department of Radiology Research, Henry Ford Health System, Detroit, MI 48202, USA; E-Mails: (N.R.S.V.); (A.S.A.)
| | - Subhash C. Gautam
- Department of General Surgery, Henry Ford Health System, Detroit, MI 48202, USA; E-Mails: (D.D.); (X.G.); (Y.L.)
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-313-874-6998
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Liu Y, Gao X, Deeb D, Arbab AS, Gautam SC. Telomerase reverse transcriptase (TERT) is a therapeutic target of oleanane triterpenoid CDDO-Me in prostate cancer. Molecules 2012; 17:14795-809. [PMID: 23519253 PMCID: PMC3607816 DOI: 10.3390/molecules171214795] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Revised: 11/20/2012] [Accepted: 12/06/2012] [Indexed: 02/08/2023] Open
Abstract
Methyl-2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oate (CDDO-Me) is an synthetic oleanane triterpenoid with strong antiprolifertive and proapoptotic activities in cancer cells. However, the effect of CDDO-Me on human telomerase reverse transcriptase (hTERT) and its telomerase activity in prostate cancer cells has not been studied. We investigated the role of hTERT in mediating the anticancer activity of CDDO-Me in prostate cancer cells in vitro and in vivo. The inhibition of cell proliferation and induction of apoptosis by CDDO-Me in LNCaP and PC-3 prostate cancer cell lines was associated with the inhibition of hTERT gene expression, hTERT telomerase activity and a number of proteins that regulate hTERT transcriptionally and post-translationally. Furthermore, ablation of hTERT protein increased the sensitivity of cancer cells to CDDO-Me, whereas its overexpression rendered them resistant to CDDO-Me. In addition, inhibition of progression of preneoplastic lesions (i.e., low and high-grade prostate intraepithelial neoplasms, PINs) to adenocarcinoma of the prostate by CDDO-Me in TRAMP mice was associated with significant decrease in TERT and its regulatory proteins in the prostate gland. These data provide evidence that telomerase is a potential target of CDDO-Me for the prevention and treatment of prostate cancer.
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Affiliation(s)
- Yongbo Liu
- Department of General Surgery, Henry Ford Health System, Detroit, MI 48202, USA; E-Mails: (B.L.); (X.G.); (D.D.)
| | - Xiaohua Gao
- Department of General Surgery, Henry Ford Health System, Detroit, MI 48202, USA; E-Mails: (B.L.); (X.G.); (D.D.)
| | - Dorrah Deeb
- Department of General Surgery, Henry Ford Health System, Detroit, MI 48202, USA; E-Mails: (B.L.); (X.G.); (D.D.)
| | - Ali S. Arbab
- Department of Radiology, Henry Ford Health System, Detroit, MI 48202, USA; E-Mail:
| | - Subhash C. Gautam
- Department of General Surgery, Henry Ford Health System, Detroit, MI 48202, USA; E-Mails: (B.L.); (X.G.); (D.D.)
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-313-874-6998
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Hodjat M, Haller H, Dumler I, Kiyan Y. Urokinase receptor mediates doxorubicin-induced vascular smooth muscle cell senescence via proteasomal degradation of TRF2. J Vasc Res 2012; 50:109-23. [PMID: 23172421 DOI: 10.1159/000343000] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Accepted: 08/23/2012] [Indexed: 11/19/2022] Open
Abstract
The anthracycline doxorubicin is a widely used effective anti-cancer drug. However, its application and dosage are severely limited due to its cardiotoxicity. The exact mechanisms of doxorubicin-induced cardiotoxic side effects remain poorly understood. Even less is known about the impact of doxorubicin treatment on vascular damage. We found that low doses of doxorubicin induced a senescent response in human primary vascular smooth muscle cells (VSMC). We observed that expression of urokinase receptor (uPAR) was upregulated in response to doxorubicin. Furthermore, the level of uPAR expression played a decisive role in developing doxorubicin-induced senescence. uPAR silencing in human VSMC by means of RNA interference as well as uPAR knockout in mouse VSMC resulted in abrogation of doxorubicin-induced cellular senescence. On the contrary, uPAR overexpression promoted VSMC senescence. We further found that proteasomal degradation of telomeric repeat binding factor 2 (TRF2) mediates doxorubicin-induced VSMC senescence. Our results demonstrate that uPAR controls the ubiquitin-proteasome system in VSMC and regulates doxorubicin-induced TRF2 ubiquitination and proteasomal degradation via this mechanism. Therefore, VSMC senescence induced by low doses of doxorubicin may contribute to vascular damage upon doxorubicin treatment. uPAR-mediated TRF2 ubiquitination and proteasomal degradation are further identified as a molecular mechanism underlying this process.
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Affiliation(s)
- Mahshid Hodjat
- Nephrology Department, Hannover Medical School, Hannover, Germany
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Jiang J, Lv W, Ye X, Wang L, Zhang M, Yang H, Okuka M, Zhou C, Zhang X, Liu L, Li J. Zscan4 promotes genomic stability during reprogramming and dramatically improves the quality of iPS cells as demonstrated by tetraploid complementation. Cell Res 2012; 23:92-106. [PMID: 23147797 DOI: 10.1038/cr.2012.157] [Citation(s) in RCA: 115] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Induced pluripotent stem (iPS) cells generated using Yamanaka factors have great potential for use in autologous cell therapy. However, genomic abnormalities exist in human iPS cells, and most mouse iPS cells are not fully pluripotent, as evaluated by the tetraploid complementation assay (TCA); this is most likely associated with the DNA damage response (DDR) occurred in early reprogramming induced by Yamanaka factors. In contrast, nuclear transfer can faithfully reprogram somatic cells into embryonic stem (ES) cells that satisfy the TCA. We thus hypothesized that factors involved in oocyte-induced reprogramming may stabilize the somatic genome during reprogramming, and improve the quality of the resultant iPS cells. To test this hypothesis, we screened for factors that could decrease DDR signals during iPS cell induction. We determined that Zscan4, in combination with the Yamanaka factors, not only remarkably reduced the DDR but also markedly promoted the efficiency of iPS cell generation. The inclusion of Zscan4 stabilized the genomic DNA, resulting in p53 downregulation. Furthermore, Zscan4 also enhanced telomere lengthening as early as 3 days post-infection through a telomere recombination-based mechanism. As a result, iPS cells generated with addition of Zscan4 exhibited longer telomeres than classical iPS cells. Strikingly, more than 50% of iPS cell lines (11/19) produced via this "Zscan4 protocol" gave rise to live-borne all-iPS cell mice as determined by TCA, compared to 1/12 for lines produced using the classical Yamanaka factors. Our findings provide the first demonstration that maintaining genomic stability during reprogramming promotes the generation of high quality iPS cells.
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Affiliation(s)
- Jing Jiang
- Group of Epigenetic Reprogramming, State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
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Huda N, Abe S, Gu L, Mendonca MS, Mohanty S, Gilley D. Recruitment of TRF2 to laser-induced DNA damage sites. Free Radic Biol Med 2012; 53:1192-7. [PMID: 22841872 DOI: 10.1016/j.freeradbiomed.2012.07.024] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Revised: 07/10/2012] [Accepted: 07/17/2012] [Indexed: 12/18/2022]
Abstract
Several lines of evidence suggest that the telomere-associated protein TRF2 plays critical roles in the DNA damage response. TRF2 is rapidly and transiently phosphorylated by an ATM-dependent pathway in response to DNA damage and this DNA damage-induced phosphoryation is essential for the DNA-PK-dependent pathway of DNA double-strand break repair (DSB). However, the type of DNA damage that induces TRF2 localization to the damage sites, the requirement for DNA damage-induced phosphorylation of TRF2 for its recruitment, as well as the detailed kinetics of TRF2 accumulation at DNA damage sites have not been fully investigated. In order to address these questions, we used an ultrafast femtosecond multiphoton laser and a continuous wave 405-nm single photon laser to induce DNA damage at defined nuclear locations. Our results showed that DNA damage produced by a femtosecond multiphoton laser was sufficient for localization of TRF2 to these DNA damage sites. We also demonstrate that ectopically expressed TRF2 was recruited to DNA lesions created by a 405-nm laser. Our data suggest that ATM and DNA-PKcs kinases are not required for TRF2 localization to DNA damage sites. Furthermore, we found that phosphorylation of TRF2 at residue T188 was not essential for its recruitment to laser-induced DNA damage sites. Thus, we provide further evidence that a protein known to function in telomere maintenance, TRF2, is recruited to sites of DNA damage and plays critical roles in the DNA damage response.
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Affiliation(s)
- Nazmul Huda
- Indiana University School of Medicine, Department of Medical and Molecular Genetics, Indianapolis, IN 46202, USA
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Butler KS, Hines WC, Heaphy CM, Griffith JK. Coordinate regulation between expression levels of telomere-binding proteins and telomere length in breast carcinomas. Cancer Med 2012; 1:165-75. [PMID: 23342266 PMCID: PMC3544452 DOI: 10.1002/cam4.14] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Revised: 05/15/2012] [Accepted: 06/01/2012] [Indexed: 02/02/2023] Open
Abstract
Telomere dysregulation occurs in both the in situ and invasive stages of many carcinomas, including breast. Knockout experiments have identified several telomere-associated proteins required for proper telomere function and maintenance, including telomere repeat-binding factor 1 and 2 (TRF1 and TRF2), protection of telomeres (POT1), and TRF1-interacting nuclear factor 2 (TIN2). Using telomere content assays and quantitative reverse transcription-polymerase chain reaction (RT-PCR), we examined the relationship between telomere length and the mRNA levels of telomere-associated proteins in breast tumors. The levels of TRF2, TRF1, TIN2, and POT1 mRNA, but not telomerase reverse transcriptase (TERT) RNA, are inversely correlated with telomere content in breast tumors. Significant associations were identified between the mRNA levels of TRF1, TIN2, and POT1; however, there were no significant associations with the mRNA levels of TRF2 or TERT. These associations suggest that a complex transcriptional program coordinately regulates the expression of these mRNAs. We examined the promoter regions of the telomere-associated proteins to identify transcription factors consistent with the observed patterns of presumed coordinate expression. We demonstrated in human breast cancer cell lines that expressions of TRF1, TIN2, and POT1 are upregulated by dexamethasone, suggesting activation of the glucocorticoid receptor, whereas TERT, TRF2, TRF1, TIN2, and POT1 are upregulated by tumor necrosis factor-α (TNF-α), suggesting activation of the nuclear factor kappa B transcription factor. These findings link telomere content in breast tumors to the coordinate expression of several telomere-associated proteins previously shown to be negative regulators of telomere length in cell lines. The results further suggest a possible link between the expressions of the telomere-associated proteins and mediators of stress and inflammation. Telomere content assays and quantitative RT-PCR demonstrate that the levels of TRF2, TRF1, TIN2, and POT1 mRNA, but not telomerase reverse transcriptase (TERT) RNA, are inversely correlated with telomere content in breast tumors. Within human breast cancer cell lines, expressions of TRF1, TIN2, and POT1 are upregulated by dexamethasone, suggesting activation of the glucocorticoid receptor, whereas TERT, TRF2, TRF1, TIN2, and POT1 are upregulated by TNF-α, suggesting activation of the NFκB transcription factor. These findings link telomere content in breast tumors to the expression of several telomere-associated proteins previously shown to be negative regulators of telomere length in cell lines and suggest a link between the expressions of the telomere-associated proteins and mediators of stress and inflammation.
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Affiliation(s)
- Kimberly S Butler
- Department of Biochemistry and Molecular Biology, University of New Mexico School of Medicine Albuquerque, New Mexico, 87131, USA
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Deeb D, Gao X, Liu Y, Kim SH, Pindolia KR, Arbab AS, Gautam SC. Inhibition of cell proliferation and induction of apoptosis by oleanane triterpenoid (CDDO-Me) in pancreatic cancer cells is associated with the suppression of hTERT gene expression and its telomerase activity. Biochem Biophys Res Commun 2012; 422:561-7. [PMID: 22609405 DOI: 10.1016/j.bbrc.2012.05.024] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Accepted: 05/04/2012] [Indexed: 01/11/2023]
Abstract
Methyl-2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oate (CDDO-Me) is a multifunctional oleanane synthetic triterpenoid with potent anti-inflammatory and antitumorigenic properties. The mechanisms of the antisurvival and apoptosis-inducing activities of CDDO-Me and related derivatives of oleanolic acid have been defined; however, to date, no study has been carried out on the effect of CDDOs on human telomerase reverse transcriptase (hTERT) gene or telomerase activity. Here we report for the first time that inhibition of cell proliferation and induction of apoptosis by CDDO-Me in pancreatic cancer cell lines is associated with the inhibition of hTERT gene expression, hTERT telomerase activity and a number of proteins that regulate hTERT expression and activity. Furthermore, abrogation or overexpression of hTERT protein altered the susceptibility of tumor cells to CDDO-Me. These findings suggest that telomerase (hTERT) is a relevant target of CDDO-Me in pancreatic cancer cells.
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Affiliation(s)
- Dorrah Deeb
- Department of Surgery, Henry Ford Health System, Detroit, MI 48202, USA
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Genetic polymorphisms in telomere pathway genes, telomere length, and breast cancer survival. Breast Cancer Res Treat 2012; 134:393-400. [PMID: 22527105 DOI: 10.1007/s10549-012-2058-9] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Accepted: 04/01/2012] [Indexed: 10/28/2022]
Abstract
The impact of genetic variants in telomere pathway genes on telomere length and breast cancer survival remains unclear. We hypothesized that telomere length and genetic variants of telomere pathway genes are associated with survival among breast cancer patients. A population-based cohort study of 1,026 women diagnosed with a first primary breast cancer was conducted to examine telomere length and 52 genetic variants of 9 telomere pathway genes. Adjusted Cox regression analysis was employed to examine associations between telomere length, genetic variants and all-cause and breast cancer-specific mortality. Longer telomere length was significantly correlated with all-cause mortality in the subgroup with HER-2/neu negative tumors (HR=1.90, 95% CI: 1.12-3.22). Carrying the PINX1-33 (rs2277130) G-allele was significantly associated with increased all-cause mortality (HR=1.45, 95% CI: 1.06-1.98). Three SNPs (TERF2-03 rs35439397, TERT-14 rs2853677, and TERT-67 rs2853669) were significantly associated with reduced all-cause mortality. A similar reduced trend for breast cancer-specific mortality was observed for carrying the TERT-14 (rs2853677) T-allele (HR=0.57, 95% CI: 0.39-0.84), while carrying the POT1-18 (rs1034794) T-allele significantly increased breast cancer-specific mortality (HR=1.48, 95% CI: 1.00-2.19). However, none of the associations remained significant after correction for multiple tests. A significant dose-response effect was observed with increased number of unfavorable alleles/genotypes (PINX1-33 G-allele, POT1-18 T-allele, TERF2-03 GG, TERT-14 CC, and TERT-67 TT genotypes) and decreased survival. These data suggest that unfavorable genetic variants in telomere pathway genes may help to predict breast cancer survival.
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Regulation of the human catalytic subunit of telomerase (hTERT). Gene 2012; 498:135-46. [PMID: 22381618 DOI: 10.1016/j.gene.2012.01.095] [Citation(s) in RCA: 199] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2011] [Revised: 01/29/2012] [Accepted: 01/30/2012] [Indexed: 12/12/2022]
Abstract
Over the past decade, there has been much interest in the regulation of telomerase, the enzyme responsible for maintaining the integrity of chromosomal ends, and its crucial role in cellular immortalization, tumorigenesis, and the progression of cancer. Telomerase activity is characterized by the expression of the telomerase reverse transcriptase (TERT) gene, suggesting that TERT serves as the major limiting agent for telomerase activity. Recent discoveries have led to characterization of various interactants that aid in the regulation of human TERT (hTERT), including numerous transcription factors; further supporting the pivotal role that transcription plays in both the expression and repression of telomerase. Several studies have suggested that epigenetic modulation of the hTERT core promoter region may provide an additional level of regulation. Although these studies have provided essential information on the regulation of hTERT, there has been ambiguity of the role of methylation within the core promoter region and the subsequent binding of various activating and repressive agents. As a result, we found it necessary to consolidate and summarize these recent developments and elucidate these discrepancies. In this review, we focus on the co-regulation of hTERT via transcriptional regulation, the presence or absence of various activators and repressors, as well as the epigenetic pathways of DNA methylation and histone modifications.
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Abstract
Telomeres, the nucleoprotein "caps" protecting the ends of linear chromosomes, are maintained by telomerase. Telomeres have important roles in maintaining genomic stability and preventing senescence or oncogenesis. Chicken is a classical model animal for genetic and developmental studies. With further development of chicken genomics, great progress has been made in research of chicken telomere and telomerase. This review describes recent advances and future research directions in chicken telomere biology.
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Durant ST. Telomerase-independent paths to immortality in predictable cancer subtypes. J Cancer 2012; 3:67-82. [PMID: 22315652 PMCID: PMC3273709 DOI: 10.7150/jca.3965] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2011] [Accepted: 01/28/2012] [Indexed: 01/17/2023] Open
Abstract
The vast majority of cancers commandeer the activity of telomerase - the remarkable enzyme responsible for prolonging cellular lifespan by maintaining the length of telomeres at the ends of chromosomes. Telomerase is only normally active in embryonic and highly proliferative somatic cells. Thus, targeting telomerase is an attractive anti-cancer therapeutic rationale currently under investigation in various phases of clinical development. However, previous reports suggest that an average of 10-15% of all cancers lose the functional activity of telomerase and most of these turn to an Alternative Lengthening of Telomeres pathway (ALT). ALT-positive tumours will therefore not respond to anti-telomerase therapies and there is a real possibility that such drugs would be toxic to normal telomerase-utilising cells and ultimately select for resistant cells that activate an ALT mechanism. ALT exploits certain DNA damage response (DDR) components to counteract telomere shortening and rapid trimming. ALT has been reported in many cancer subtypes including sarcoma, gastric carcinoma, central nervous system malignancies, subtypes of kidney (Wilm's Tumour) and bladder carcinoma, mesothelioma, malignant melanoma and germ cell testicular cancers to name but a few. A recent heroic study that analysed ALT in over six thousand tumour samples supports this historical spread, although only reporting an approximate 4% prevalence. This review highlights the various methods of ALT detection, unravels several molecular ALT models thought to promote telomere maintenance and elongation, spotlights the DDR components known to facilitate these and explores why certain tissues are more likely to subvert DDR away from its usually protective functions, resulting in a predictive pattern of prevalence in specific cancer subsets.
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Affiliation(s)
- Stephen T Durant
- AstraZeneca - DNA Damage Response, Bioscience, Oncology iMed, Alderley Park, Cheshire, SK10 4TG, England, UK
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