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Kostopoulou E, Rojas Gil AP, Spiliotis BE. The role of p21/CIP1/WAF1 (p21) in the negative regulation of the growth hormone/growth hormone receptor and epidermal growth factor/epidermal growth factor receptor pathways, in growth hormone transduction defect. Ann Pediatr Endocrinol Metab 2018; 23:204-209. [PMID: 30599481 PMCID: PMC6312915 DOI: 10.6065/apem.2018.23.4.204] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2018] [Accepted: 10/17/2018] [Indexed: 11/20/2022] Open
Abstract
PURPOSE Growth hormone transduction defect (GHTD) is characterized by severe short stature, impaired STAT3 (signal transducer and activator of transcription-3) phosphorylation and overexpression of the cytokine inducible SH2 containing protein (CIS) and p21/CIP1/WAF1. To investigate the role of p21/CIP1/WAF1 in the negative regulation of the growth hormone (GH)/GH receptor and Epidermal Growth Factor (EGF)/EGF Receptor pathways in GHTD. METHODS Fibroblast cultures were developed from gingival biopsies of 1 GHTD patient and 1 control. The protein expression and the cellular localization of p21/CIP1/WAF1 was studied by Western immunoblotting and immunofluorescence, respectively: at the basal state and after induction with 200-μg/L human GH (hGH) (GH200), either with or without siRNA CIS (siCIS); at the basal state and after inductions with 200-μg/L hGH (GH200), 1,000-μg/L hGH (GH1000) or 50-ng/mL EGF. RESULTS After GH200/siCIS, the protein expression and nuclear localization of p21 were reduced in the patient. After successful induction of GH signaling (control, GH200; patient, GH1000), the protein expression and nuclear localization of p21 were reduced. After induction with EGF, p21 translocated to the cytoplasm in the control, whereas in the GHTD patient it remained located in the nucleus. CONCLUSION In the GHTD fibroblasts, when CIS is reduced, either after siCIS or after a higher dose of hGH (GH1000), p21's antiproliferative effect (nuclear localization) is also reduced and GH signaling is activated. There also appears to be a positive relationship between the 2 inhibitors of GH signaling, CIS and p21. Finally, in GHTD, p21 seems to participate in the regulation of both the GH and EGF/EGFR pathways, depending upon its cellular location.
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Affiliation(s)
- Eirini Kostopoulou
- Paediatric Endocrine Research Laboratory, Division of Paediatric Endocrinology and Diabetes, Department of Paediatrics, University of Patras School of Medicine, Patras, Greece,Address for correspondence: Eirini Kostopoulou, MD, PhD Paediatric Endocrine Research Laboratory, Division of Paediatric Endocrinology and Diabetes, Department of Paediatrics, University of Patras School of Medicine, Patras 26504, Greece Tel: +30-6972070117 Fax: +30-2610-994-633 E-mail:
| | - Andrea Paola Rojas Gil
- Faculty of Human Movement and Quality of Life Sciences, Department of Nursing, University of Peloponnese, Sparta, Greece
| | - Bessie E. Spiliotis
- Paediatric Endocrine Research Laboratory, Division of Paediatric Endocrinology and Diabetes, Department of Paediatrics, University of Patras School of Medicine, Patras, Greece
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Mukherjee AK, Sharma S, Sengupta S, Saha D, Kumar P, Hussain T, Srivastava V, Roy SD, Shay JW, Chowdhury S. Telomere length-dependent transcription and epigenetic modifications in promoters remote from telomere ends. PLoS Genet 2018; 14:e1007782. [PMID: 30439955 PMCID: PMC6264879 DOI: 10.1371/journal.pgen.1007782] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 11/29/2018] [Accepted: 10/23/2018] [Indexed: 12/03/2022] Open
Abstract
Telomere-binding proteins constituting the shelterin complex have been studied primarily for telomeric functions. However, mounting evidence shows non-telomeric binding and gene regulation by shelterin factors. This raises a key question—do telomeres impact binding of shelterin proteins at distal non-telomeric sites? Here we show that binding of the telomere-repeat-binding-factor-2 (TRF2) at promoters ~60 Mb from telomeres depends on telomere length in human cells. Promoter TRF2 occupancy was depleted in cells with elongated telomeres resulting in altered TRF2-mediated transcription of distal genes. In addition, histone modifications—activation (H3K4me1 and H3K4me3) as well as silencing marks (H3K27me3)—at distal promoters were telomere length-dependent. These demonstrate that transcription, and the epigenetic state, of telomere-distal promoters can be influenced by telomere length. Molecular links between telomeres and the extra-telomeric genome, emerging from findings here, might have important implications in telomere-related physiology, particularly ageing and cancer. Telomeres (special DNA-protein assemblies that protect chromosome ends) affect ageing and diseases such as cancer. Although this has been recognized for many years, biological processes that connect telomeres to ageing, cancer and other cellular functions remain to be fully understood. Certain proteins, believed to be only telomere-associated, engage DNA outside telomeres. This raises an interesting question. Does telomere length influence how telomere-binding proteins associate with DNA at regions distal from telomeres. If so, how does this impact function? Motivated by these questions, in the present studies we tested if extra-telomeric binding of the well-known telomere-repeat-binding-actor-2 (TRF2) depends on telomere length. Our results show that the level of DNA-bound TRF2 at telomere-distal sites changes as telomeres shorten or elongate. Consequently, TRF2-mediated gene regulation affects many genes. Notably, histone modifications that dictate chromatin compaction and access to regulatory factors, at sites distant from telomere ends also depended on telomere length. Together, this links the state of telomeres to gene regulation and epigenetics directly in ways not previously appreciated that might impact a more complete understanding of molecular processes underlying ageing and cancer.
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Affiliation(s)
- Ananda Kishore Mukherjee
- Genomics and Molecular Medicine Unit, CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
- Academy of Scientific and Innovative Research, CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
| | - Shalu Sharma
- Genomics and Molecular Medicine Unit, CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
- Academy of Scientific and Innovative Research, CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
| | - Suman Sengupta
- Genomics and Molecular Medicine Unit, CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
| | - Dhurjhoti Saha
- Genomics and Molecular Medicine Unit, CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
| | - Pankaj Kumar
- Academy of Scientific and Innovative Research, CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
- G.N.R. Knowledge Centre for Genome Informatics, CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
| | - Tabish Hussain
- Genomics and Molecular Medicine Unit, CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
| | - Vivek Srivastava
- Genomics and Molecular Medicine Unit, CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
| | - Sumitabho Deb Roy
- Genomics and Molecular Medicine Unit, CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
| | - Jerry W. Shay
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Shantanu Chowdhury
- Genomics and Molecular Medicine Unit, CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
- Academy of Scientific and Innovative Research, CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
- G.N.R. Knowledge Centre for Genome Informatics, CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
- * E-mail:
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103
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Assani G, Xiong Y, Zhou F, Zhou Y. Effect of therapies-mediated modulation of telomere and/or telomerase on cancer cells radiosensitivity. Oncotarget 2018; 9:35008-35025. [PMID: 30405890 PMCID: PMC6201854 DOI: 10.18632/oncotarget.26150] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 07/31/2018] [Indexed: 12/11/2022] Open
Abstract
Cancer is one of the leading causes of death in the world. Many strategies of cancer treatment such as radiotherapy which plays a key role in cancer treatment are developed and used nowadays. However, the side effects post-cancer radiotherapy and cancer radioresistance are two major causes of the limitation of cancer radiotherapy effectiveness in the cancer patients. Moreover, reduction of the limitation of cancer radiotherapy effectiveness by reducing the side effects post-cancer radiotherapy and cancer radioresistance is the aim of several radiotherapy-oncologic teams. Otherwise, Telomere and telomerase are two cells components which play an important role in cancer initiation, cancer progression and cancer therapy resistance such as radiotherapy resistance. For resolving the problems of the limitation of cancer radiotherapy effectiveness especially the cancer radio-resistance problems, the radio-gene-therapy strategy which is the use of gene-therapy via modulation of gene expression combined with radiotherapy was developed and used as a new strategy to treat the patients with cancer. In this review, we summarized the information concerning the implication of telomere and telomerase modulation in cancer radiosensitivity.
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Affiliation(s)
- Ganiou Assani
- Department of Radiation and Medical Oncology, Zhongnan Hospital of Wuhan University, Wuhan, China
- Hubei Cancer Clinical Study Center, Zhongnan Hospital of Wuhan University, Wuhan, China
- Hubei Key Laboratory of Tumor Biology Behaviors, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Yudi Xiong
- Department of Radiation and Medical Oncology, Zhongnan Hospital of Wuhan University, Wuhan, China
- Hubei Cancer Clinical Study Center, Zhongnan Hospital of Wuhan University, Wuhan, China
- Hubei Key Laboratory of Tumor Biology Behaviors, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Fuxiang Zhou
- Department of Radiation and Medical Oncology, Zhongnan Hospital of Wuhan University, Wuhan, China
- Hubei Cancer Clinical Study Center, Zhongnan Hospital of Wuhan University, Wuhan, China
- Hubei Key Laboratory of Tumor Biology Behaviors, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Yunfeng Zhou
- Department of Radiation and Medical Oncology, Zhongnan Hospital of Wuhan University, Wuhan, China
- Hubei Cancer Clinical Study Center, Zhongnan Hospital of Wuhan University, Wuhan, China
- Hubei Key Laboratory of Tumor Biology Behaviors, Zhongnan Hospital of Wuhan University, Wuhan, China
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Ludlow AT, Wong MS, Robin JD, Batten K, Yuan L, Lai TP, Dahlson N, Zhang L, Mender I, Tedone E, Sayed ME, Wright WE, Shay JW. NOVA1 regulates hTERT splicing and cell growth in non-small cell lung cancer. Nat Commun 2018; 9:3112. [PMID: 30082712 PMCID: PMC6079032 DOI: 10.1038/s41467-018-05582-x] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Accepted: 07/12/2018] [Indexed: 12/12/2022] Open
Abstract
Alternative splicing is dysregulated in cancer and the reactivation of telomerase involves the splicing of TERT transcripts to produce full-length (FL) TERT. Knowledge about the splicing factors that enhance or silence FL hTERT is lacking. We identified splicing factors that reduced telomerase activity and shortened telomeres using a siRNA minigene reporter screen and a lung cancer cell bioinformatics approach. A lead candidate, NOVA1, when knocked down resulted in a shift in hTERT splicing to non-catalytic isoforms, reduced telomerase activity, and progressive telomere shortening. NOVA1 knockdown also significantly altered cancer cell growth in vitro and in xenografts. Genome engineering experiments reveal that NOVA1 promotes the inclusion of exons in the reverse transcriptase domain of hTERT resulting in the production of FL hTERT transcripts. Utilizing hTERT splicing as a model splicing event in cancer may provide new insights into potentially targetable dysregulated splicing factors in cancer.
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Affiliation(s)
- Andrew T Ludlow
- Department of Cell Biology, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, 75390, USA.
- School of Kinesiology, University of Michigan, 401 Washtenaw Ave., Ann Arbor, MI, 48109, USA.
| | - Mandy Sze Wong
- Department of Cell Biology, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, 75390, USA
- Cold Spring Harbor Laboratories, One Bungtown Road, Cold Spring Harbor, New York, NY, 11724, USA
| | - Jerome D Robin
- Department of Cell Biology, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, 75390, USA
- Aix-Marseille University, Marseille Medical Genetics (MMG), UMR125, Marseille, 13385, France
| | - Kimberly Batten
- Department of Cell Biology, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, 75390, USA
| | - Laura Yuan
- Department of Cell Biology, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, 75390, USA
| | - Tsung-Po Lai
- Department of Cell Biology, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, 75390, USA
| | - Nicole Dahlson
- Department of Cell Biology, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, 75390, USA
| | - Lu Zhang
- Department of Cell Biology, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, 75390, USA
| | - Ilgen Mender
- Department of Cell Biology, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, 75390, USA
| | - Enzo Tedone
- Department of Cell Biology, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, 75390, USA
| | - Mohammed E Sayed
- Department of Cell Biology, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, 75390, USA
- School of Kinesiology, University of Michigan, 401 Washtenaw Ave., Ann Arbor, MI, 48109, USA
| | - Woodring E Wright
- Department of Cell Biology, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, 75390, USA
| | - Jerry W Shay
- Department of Cell Biology, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, 75390, USA
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105
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Luke B. Telomere regulation. Differentiation 2018; 102:27-29. [PMID: 30056220 DOI: 10.1016/j.diff.2018.06.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Brian Luke
- Institute of Neurobiology and Developmental Biology, Johannes Gutenberg University, IMB-Mainz, Ackermannweg 4, 55128 Mainz, Germany.
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106
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Guo LQ, Chen Y, Teng XL, Xia WB, Xu J, Qu YK. TERT expression in gastric carcinogenesis: Correlation with clinical features. Shijie Huaren Xiaohua Zazhi 2018; 26:979-985. [DOI: 10.11569/wcjd.v26.i16.979] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM To investigate the expression of telomerase reverse transcriptase (TERT) mRNA in gastric cancer and precancerous lesions, and to analyze the relationship between TERT expression and clinicopathologic features and prognosis in gastric cancer.
METHODS From September 2011 to October 2016, 102 patients with gastric cancer, 32 patients with precancerous lesions, and 30 patients with chronic non-atrophic gastritis were treated at the First Affiliated Hospital of Jiamus University. The expression of TERT mRNA in tissues was detected by real-time quantitative PCR, and the correlation of expression of TERT with clinicopathologic features and prognosis in gastric cancer was analyzed.
RESULTS The expression of TERT in gastric cancer and precancerous lesions was significantly higher than that in chronic non-atrophic gastritis (P < 0.05). TERT expression was significantly correlated with the depth of invasion, TNM stage, vascular invasion, and lymph node metastasis (P < 0.05). The overall survival rate of gastric cancer patients with high expression of TERT was significantly lower than that of patients with low expression of TERT (HR = 0.420, 95%CI: 0.264-0.668, P < 0.001). The progression-free survival rate of gastric cancer patients with high expression of TERT was also significantly lower than that of patients with low TERT expression (HR = 0.649, 95%CI: 0.421-0.999, P = 0.049). Cox multivariate survival analysis showed that TERT expression was an independent prognostic factor for overall survival in gastric cancer.
CONCLUSION TERT is highly expressed in gastric cancer and precancerous lesions, and high expression of TERT is significantly associated with the clinicopathologic features and prognosis of gastric cancer patients.
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Affiliation(s)
- Lin-Qi Guo
- the Second Department of General Surgery, the First Affiliated Hospital of Jiamus University, Jiamus 154003, Heilongjiang Province, China
| | - Ying Chen
- the Second Department of General Surgery, the First Affiliated Hospital of Jiamus University, Jiamus 154003, Heilongjiang Province, China
| | - Xin-Li Teng
- the Second Department of radiology, the Oncology Hospital of Jiamus, Jiamus 154007, Heilongjiang Province, China
| | - Wei-Bin Xia
- the Second Department of General Surgery, the First Affiliated Hospital of Jiamus University, Jiamus 154003, Heilongjiang Province, China
| | - Jian Xu
- the Second Department of General Surgery, the First Affiliated Hospital of Jiamus University, Jiamus 154003, Heilongjiang Province, China
| | - Yi-Kun Qu
- the Second Department of General Surgery, the First Affiliated Hospital of Jiamus University, Jiamus 154003, Heilongjiang Province, China
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107
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Telomeres and aging. Curr Opin Cell Biol 2018; 52:1-7. [DOI: 10.1016/j.ceb.2017.12.001] [Citation(s) in RCA: 92] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 11/29/2017] [Accepted: 12/03/2017] [Indexed: 12/26/2022]
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108
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Roy S, Roy S, Rana A, Akhter Y, Hande MP, Banerjee B. The role of p38 MAPK pathway in p53 compromised state and telomere mediated DNA damage response. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2018; 836:89-97. [PMID: 30389168 DOI: 10.1016/j.mrgentox.2018.05.018] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2018] [Revised: 04/17/2018] [Accepted: 05/26/2018] [Indexed: 12/19/2022]
Abstract
There is an intricate balance of DNA damage response and repair which determines the homeostasis of human genome function. p53 protein is widely known for its role in cell cycle regulation and tumor suppressor activity. In case of several cancers where function of p53 gene gets compromised either by mutation or partial inactivation, the role of p53 in response to DNA damage needs to be supplemented by another molecule or pathway. Due to sedentary lifestyle and exposure to genotoxic agents, genome is predisposed to chronic stress, which ultimately leads to unrepaired or background DNA damage. p38 MAPK signaling pathway is strongly activated in response to various environmental and cellular stresses. DNA damage response and the repair options have crucial links with chromosomal integrity. Telomere that regulates integrity of genome is protected by a six member shielding unit called shelterin complex which communicates with other pathways for functionality of telomeres. There are evidences that p38 gets activated through ATM in response to DNA damage. Dysfunctional telomere leads to activation of ATM which subsequently activates p38 suggesting a crosstalk between p38, ATM and shelterin complex. This review focuses on activation of p38 in response to genotoxic stress induced DNA damage in p53 mutated or compromised state and its possible cross talk with telomere shelterin proteins. Thus p38 may act as an important target to treat various diseases and in majority of cancers in p53 mutated state.
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Affiliation(s)
- Shomereeta Roy
- Molecular Stress and Stem Cell Biology Group, School of Biotechnology, KIIT University, Bhubaneswar, Odisha-751024, India
| | - Souvick Roy
- Molecular Stress and Stem Cell Biology Group, School of Biotechnology, KIIT University, Bhubaneswar, Odisha-751024, India
| | - Aarti Rana
- Centre for Computational Biology and Bioinformatics, School of Life Sciences, Central University of Himachal Pradesh, Shahpur, Himachal Pradesh-176206, India
| | - Yusuf Akhter
- Department of Biotechnology, Babasaheb Bhimrao Ambedkar University, Vidya Vihar, Raebareli Road, Lucknow, Uttar Pradesh 226025, India
| | - Manoor Prakash Hande
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117593, Singapore
| | - Birendranath Banerjee
- Molecular Stress and Stem Cell Biology Group, School of Biotechnology, KIIT University, Bhubaneswar, Odisha-751024, India.
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Lidzbarsky G, Gutman D, Shekhidem HA, Sharvit L, Atzmon G. Genomic Instabilities, Cellular Senescence, and Aging: In Vitro, In Vivo and Aging-Like Human Syndromes. Front Med (Lausanne) 2018; 5:104. [PMID: 29719834 PMCID: PMC5913290 DOI: 10.3389/fmed.2018.00104] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2018] [Accepted: 03/29/2018] [Indexed: 12/20/2022] Open
Abstract
As average life span and elderly people prevalence in the western world population is gradually increasing, the incidence of age-related diseases such as cancer, heart diseases, diabetes, and dementia is increasing, bearing social and economic consequences worldwide. Understanding the molecular basis of aging-related processes can help extend the organism’s health span, i.e., the life period in which the organism is free of chronic diseases or decrease in basic body functions. During the last few decades, immense progress was made in the understanding of major components of aging and healthy aging biology, including genomic instability, telomere attrition, epigenetic changes, proteostasis, nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, and intracellular communications. This progress has been made by three spear-headed strategies: in vitro (cell and tissue culture from various sources), in vivo (includes diverse model and non-model organisms), both can be manipulated and translated to human biology, and the study of aging-like human syndromes and human populations. Herein, we will focus on current repository of genomic “senescence” stage of aging, which includes health decline, structural changes of the genome, faulty DNA damage response and DNA damage, telomere shortening, and epigenetic alterations. Although aging is a complex process, many of the “hallmarks” of aging are directly related to DNA structure and function. This review will illustrate the variety of these studies, done in in vitro, in vivo and human levels, and highlight the unique potential and contribution of each research level and eventually the link between them.
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Affiliation(s)
| | - Danielle Gutman
- Department of Human Biology, University of Haifa, Haifa, Israel
| | | | - Lital Sharvit
- Department of Human Biology, University of Haifa, Haifa, Israel
| | - Gil Atzmon
- Department of Human Biology, University of Haifa, Haifa, Israel
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110
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Song S, Johnson FB. Epigenetic Mechanisms Impacting Aging: A Focus on Histone Levels and Telomeres. Genes (Basel) 2018; 9:genes9040201. [PMID: 29642537 PMCID: PMC5924543 DOI: 10.3390/genes9040201] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2018] [Revised: 03/27/2018] [Accepted: 03/29/2018] [Indexed: 12/13/2022] Open
Abstract
Aging and age-related diseases pose some of the most significant and difficult challenges to modern society as well as to the scientific and medical communities. Biological aging is a complex, and, under normal circumstances, seemingly irreversible collection of processes that involves numerous underlying mechanisms. Among these, chromatin-based processes have emerged as major regulators of cellular and organismal aging. These include DNA methylation, histone modifications, nucleosome positioning, and telomere regulation, including how these are influenced by environmental factors such as diet. Here we focus on two interconnected categories of chromatin-based mechanisms impacting aging: those involving changes in the levels of histones or in the functions of telomeres.
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Affiliation(s)
- Shufei Song
- Biochemistry and Molecular Biophysics Graduate Group, Biomedical Graduate Studies, University of Pennsylvania, Philadelphia, PA 19104, USA.
- Department of Pathology and Laboratory Medicine, and Institute on Aging, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
| | - F Brad Johnson
- Department of Pathology and Laboratory Medicine, and Institute on Aging, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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111
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Young AJ. The role of telomeres in the mechanisms and evolution of life-history trade-offs and ageing. Philos Trans R Soc Lond B Biol Sci 2018; 373:20160452. [PMID: 29335379 PMCID: PMC5784072 DOI: 10.1098/rstb.2016.0452] [Citation(s) in RCA: 124] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/19/2017] [Indexed: 12/16/2022] Open
Abstract
Evolutionary biology and biomedicine have seen a surge of recent interest in the possibility that telomeres play a role in life-history trade-offs and ageing. Here, I evaluate alternative hypotheses for the role of telomeres in the mechanisms and evolution of life-history trade-offs and ageing, and highlight outstanding challenges. First, while recent findings underscore the possibility of a proximate causal role for telomeres in current-future trade-offs and ageing, it is currently unclear (i) whether telomeres ever play a causal role in either and (ii) whether any causal role for telomeres arises via shortening or length-independent mechanisms. Second, I consider why, if telomeres do play a proximate causal role, selection has not decoupled such a telomere-mediated trade-off between current and future performance. Evidence suggests that evolutionary constraints have not rendered such decoupling impossible. Instead, a causal role for telomeres would more plausibly reflect an adaptive strategy, born of telomere maintenance costs and/or a function for telomere attrition (e.g. in countering cancer), the relative importance of which is currently unclear. Finally, I consider the potential for telomere biology to clarify the constraints at play in life-history evolution, and to explain the form of the current-future trade-offs and ageing trajectories that we observe today.This article is part of the theme issue 'Understanding diversity in telomere dynamics'.
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Affiliation(s)
- Andrew J Young
- School of Biosciences, University of Exeter Penryn Campus, Penryn TR10 9FE, UK
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112
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Bateson M, Nettle D. Why are there associations between telomere length and behaviour? Philos Trans R Soc Lond B Biol Sci 2018; 373:20160438. [PMID: 29335363 PMCID: PMC5784059 DOI: 10.1098/rstb.2016.0438] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/13/2017] [Indexed: 12/30/2022] Open
Abstract
Individual differences in telomere length are associated with individual differences in behaviour in humans and birds. Within the human epidemiological literature this association is assumed to result from specific behaviour patterns causing changes in telomere dynamics. We argue that selective adoption-the hypothesis that individuals with short telomeres are more likely to adopt specific behaviours-is an alternative worthy of consideration. Selective adoption could occur either because telomere length directly affects behaviour or because behaviour and telomere length are both affected by a third variable, such as exposure to early-life adversity. We present differential predictions of the causation and selective adoption hypotheses and describe how these could be tested with longitudinal data on telomere length. Crucially, if behaviour is causal then it should be associated with differential rates of telomere attrition. Using smoking behaviour as an example, we show that the evidence that smoking accelerates the rate of telomere attrition within individuals is currently weak. We conclude that the selective adoption hypothesis for the association between behaviour and telomere length is both mechanistically plausible and, if anything, more compatible with existing empirical evidence than the hypothesis that behaviour is causal.This article is part of the theme issue 'Understanding diversity in telomere dynamics'.
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Affiliation(s)
- Melissa Bateson
- Centre for Behaviour and Evolution and Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Daniel Nettle
- Centre for Behaviour and Evolution and Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
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113
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Pristyazhnyuk IE, Menzorov AG. Ring chromosomes: from formation to clinical potential. PROTOPLASMA 2018; 255:439-449. [PMID: 28894962 DOI: 10.1007/s00709-017-1165-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Accepted: 08/31/2017] [Indexed: 06/07/2023]
Abstract
Ring chromosomes (RCs) are circular DNA molecules, which occur rarely in eukaryotic nuclear genomes. Lilian Vaughan Morgan first described them in the fruit fly. Human embryos very seldom have RCs, about 1:50,000. Carriers of RCs may have varying degrees of symptoms, from healthy phenotype to serious pathologies in physical and intellectual development. Many authors describe common symptoms of RC presence: short stature and some developmental delay that could be described as a "ring chromosome syndrome." As a rule, RCs arise de novo through the end-joining of two DNA double-strand breaks, telomere-subtelomere junction, or inv dup del rearrangement in both meiosis and mitosis. There are family cases of RC inheritance. The presence of RCs causes numerous secondary chromosome rearrangements in vivo and in vitro. RCs can change their size, become lost, or increase their copy number and cause additional deletions, duplication, and translocations, affecting both RCs and other chromosomes. In this review, we examine RC inheritance, instability, mechanisms of formation, and potential clinical applications of artificially created RCs for large-scale chromosome rearrangement treatment.
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Affiliation(s)
- Inna E Pristyazhnyuk
- Sector of Genomic Mechanisms of Ontogenesis, Federal Research Center Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia, 630090.
| | - Aleksei G Menzorov
- Sector of Cell Collections, Federal Research Center Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia, 630090
- Natural Sciences Department, Novosibirsk State University, Novosibirsk, Russia, 630090
- Research Institute of Medical Genetics, Tomsk National Research Medical Center Russian Academy of Sciences, Tomsk, Russia, 634050
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114
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Telford M, Navarro A, Santpere G. Whole genome diversity of inherited chromosomally integrated HHV-6 derived from healthy individuals of diverse geographic origin. Sci Rep 2018; 8:3472. [PMID: 29472617 PMCID: PMC5823862 DOI: 10.1038/s41598-018-21645-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 01/31/2018] [Indexed: 12/13/2022] Open
Abstract
Human herpesviruses 6-A and -B (HHV-6A, HHV-6B) are ubiquitous in human populations worldwide. These viruses have been associated with several diseases such as multiple sclerosis, Hodgkin's lymphoma or encephalitis. Despite of the need to understand the genetic diversity and geographic stratification of these viruses, the availability of complete viral sequences from different populations is still limited. Here, we present nine new inherited chromosomally integrated HHV-6 sequences from diverse geographical origin which were generated through target DNA enrichment on lymphoblastoid cell lines derived from healthy individuals. Integration with available HHV-6 sequences allowed the assessment of HHV-6A and -6B phylogeny, patterns of recombination and signatures of natural selection. Analysis of the intra-species variability showed differences between A and B diversity levels and revealed that the HHV-6B reference (Z29) is an uncommon sequence, suggesting the need for an alternative reference sequence. Signs of geographical variation are present and more defined in HHV-6A, while they appear partly masked by recombination in HHV-6B. Finally, we conducted a scan for signatures of selection in protein coding genes that yielded at least 6 genes (4 and 2 respectively for the A and B species) showing significant evidence for accelerated evolution, and 1 gene showing evidence of positive selection in HHV-6A.
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Affiliation(s)
- Marco Telford
- Institute of Evolutionary Biology (UPF-CSIC), Departament de Ciències Experimentals i la Salut, Universitat Pompeu Fabra, PRBB, Barcelona, Catalonia, Spain
| | - Arcadi Navarro
- Institute of Evolutionary Biology (UPF-CSIC), Departament de Ciències Experimentals i la Salut, Universitat Pompeu Fabra, PRBB, Barcelona, Catalonia, Spain.
- National Institute for Bioinformatics (INB), PRBB, Barcelona, Catalonia, Spain.
- Institució Catalana de Recerca i Estudis Avançats (ICREA), PRBB, Barcelona, Catalonia, Spain.
- Center for Genomic Regulation (CRG), PRBB, Barcelona, Catalonia, Spain.
| | - Gabriel Santpere
- Institute of Evolutionary Biology (UPF-CSIC), Departament de Ciències Experimentals i la Salut, Universitat Pompeu Fabra, PRBB, Barcelona, Catalonia, Spain.
- Department of Neuroscience, Yale School of Medicine, New Haven, CT, 06510, USA.
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115
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Roy SS, Mukherjee AK, Chowdhury S. Insights about genome function from spatial organization of the genome. Hum Genomics 2018; 12:8. [PMID: 29458419 PMCID: PMC5819253 DOI: 10.1186/s40246-018-0140-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 02/11/2018] [Indexed: 03/04/2023] Open
Abstract
Over the last 15 years, development of chromosome conformation capture (3C) and its subsequent high-throughput variants in conjunction with the fast development of sequencing technology has allowed investigators to generate large volumes of data giving insights into the spatial three-dimensional (3D) architecture of the genome. This huge data has been analyzed and validated using various statistical, mathematical, genomics, and biophysical tools in order to examine the chromosomal interaction patterns, understand the organization of the chromosome, and find out functional implications of the interactions. This review summarizes the data generated by several large-scale high-throughput chromosome conformation capture studies and the functional implications obtained from the data analyses. We also discuss emerging results on factors (both CCCTC binding factor (CTCF) related and CTCF independent) that could contribute to looping interactions.
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Affiliation(s)
- Shuvra Shekhar Roy
- Genomics and Molecular Medicine Unit, CSIR-Institute of Genomics and Integrative Biology, Mathura Road, New Delhi, 110025, India
| | - Ananda Kishore Mukherjee
- Genomics and Molecular Medicine Unit, CSIR-Institute of Genomics and Integrative Biology, Mathura Road, New Delhi, 110025, India.,Academy of Scientific and Innovative Research, CSIR-Institute of Genomics and Integrative Biology, Mathura Road, New Delhi, 110025, India
| | - Shantanu Chowdhury
- Genomics and Molecular Medicine Unit, CSIR-Institute of Genomics and Integrative Biology, Mathura Road, New Delhi, 110025, India. .,Academy of Scientific and Innovative Research, CSIR-Institute of Genomics and Integrative Biology, Mathura Road, New Delhi, 110025, India.
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116
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Seeker LA, Ilska JJ, Psifidi A, Wilbourn RV, Underwood SL, Fairlie J, Holland R, Froy H, Bagnall A, Whitelaw B, Coffey M, Nussey DH, Banos G. Longitudinal changes in telomere length and associated genetic parameters in dairy cattle analysed using random regression models. PLoS One 2018; 13:e0192864. [PMID: 29438415 PMCID: PMC5811042 DOI: 10.1371/journal.pone.0192864] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2017] [Accepted: 01/31/2018] [Indexed: 11/18/2022] Open
Abstract
Telomeres cap the ends of linear chromosomes and shorten with age in many organisms. In humans short telomeres have been linked to morbidity and mortality. With the accumulation of longitudinal datasets the focus shifts from investigating telomere length (TL) to exploring TL change within individuals over time. Some studies indicate that the speed of telomere attrition is predictive of future disease. The objectives of the present study were to 1) characterize the change in bovine relative leukocyte TL (RLTL) across the lifetime in Holstein Friesian dairy cattle, 2) estimate genetic parameters of RLTL over time and 3) investigate the association of differences in individual RLTL profiles with productive lifespan. RLTL measurements were analysed using Legendre polynomials in a random regression model to describe TL profiles and genetic variance over age. The analyses were based on 1,328 repeated RLTL measurements of 308 female Holstein Friesian dairy cattle. A quadratic Legendre polynomial was fitted to the fixed effect of age in months and to the random effect of the animal identity. Changes in RLTL, heritability and within-trait genetic correlation along the age trajectory were calculated and illustrated. At a population level, the relationship between RLTL and age was described by a positive quadratic function. Individuals varied significantly regarding the direction and amount of RLTL change over life. The heritability of RLTL ranged from 0.36 to 0.47 (SE = 0.05-0.08) and remained statistically unchanged over time. The genetic correlation of RLTL at birth with measurements later in life decreased with the time interval between samplings from near unity to 0.69, indicating that TL later in life might be regulated by different genes than TL early in life. Even though animals differed in their RLTL profiles significantly, those differences were not correlated with productive lifespan (p = 0.954).
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Affiliation(s)
- Luise A. Seeker
- Animal & Veterinary Sciences, SRUC, Easter Bush, Midlothian, United Kingdom
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian, United Kingdom
- * E-mail:
| | - Joanna J. Ilska
- Animal & Veterinary Sciences, SRUC, Easter Bush, Midlothian, United Kingdom
| | - Androniki Psifidi
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian, United Kingdom
- Royal Veterinary College, University of London, Hatfield, United Kingdom
| | - Rachael V. Wilbourn
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, Midlothian, United Kingdom
| | - Sarah L. Underwood
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, Midlothian, United Kingdom
| | - Jennifer Fairlie
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, Midlothian, United Kingdom
| | - Rebecca Holland
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, Midlothian, United Kingdom
| | - Hannah Froy
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, Midlothian, United Kingdom
| | | | - Bruce Whitelaw
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian, United Kingdom
| | - Mike Coffey
- Animal & Veterinary Sciences, SRUC, Easter Bush, Midlothian, United Kingdom
| | - Daniel H. Nussey
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, Midlothian, United Kingdom
| | - Georgios Banos
- Animal & Veterinary Sciences, SRUC, Easter Bush, Midlothian, United Kingdom
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian, United Kingdom
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117
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Chang ACY, Blau HM. Short telomeres - A hallmark of heritable cardiomyopathies. Differentiation 2018; 100:31-36. [PMID: 29482077 DOI: 10.1016/j.diff.2018.02.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 02/06/2018] [Accepted: 02/07/2018] [Indexed: 12/15/2022]
Abstract
Cardiovascular diseases are the leading cause of death worldwide and the incidence increases with age. Genetic testing has taught us much about the pathogenic pathways that drive heritable cardiomyopathies. Here we discuss an unexpected link between shortened telomeres, a molecular marker of aging, and genetic cardiomyopathy. Positioned at the ends of chromosomes, telomeres are DNA repeats which serve as protective caps that shorten with each cell division in proliferative tissues. Cardiomyocytes are an anomaly, as they are largely non-proliferative post-birth and retain relatively stable telomere lengths throughout life in healthy individuals. However, there is mounting evidence that in disease states, cardiomyocyte telomeres significantly shorten. Moreover, this shortening may play an active role in the development of mitochondrial dysfunction central to the etiology of dilated and hypertrophic cardiomyopathies. Elucidation of the mechanisms that underlie the telomere-mitochondrial signaling axis in the heart will provide fresh insights into our understanding of genetic cardiomyopathies, and could lead to the identification of previously uncharacterized modes of therapeutic intervention.
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Affiliation(s)
- Alex C Y Chang
- Baxter Laboratory for Stem Cell Biology, Department of Microbiology and Immunology, Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, USA; Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA, USA; Stanford Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA, USA.
| | - Helen M Blau
- Baxter Laboratory for Stem Cell Biology, Department of Microbiology and Immunology, Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, USA; Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA, USA.
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118
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Kim W, Shay JW. Long-range telomere regulation of gene expression: Telomere looping and telomere position effect over long distances (TPE-OLD). Differentiation 2018; 99:1-9. [PMID: 29197683 PMCID: PMC5826875 DOI: 10.1016/j.diff.2017.11.005] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Revised: 11/11/2017] [Accepted: 11/21/2017] [Indexed: 01/09/2023]
Abstract
The human cellular reverse transcriptase, telomerase, is very tightly regulated in large long-lived species. Telomerase is expressed during early human fetal development, is turned off in most adult tissues, and then becomes reactivated in almost all human cancers. However, the exact mechanism regulating these switches in expression are not known. We recently described a phenomenon where genes are regulated by telomere length dependent loops (telomere position effects over long distances; TPE-OLD). The hTERT gene is ~ 1.2Mb from the human chromosome 5p end. We observed that when telomeres are long hTERT gene expression is repressed and a probe next to the 5p telomere and the hTERT locus are spatially co-localized. When telomeres are short at least one of the hTERT alleles is spatially separated from the telomere, developing more active histone marks and changes in DNA methylation in the hTERT promoter region. These findings have implications for how cells turn off telomerase when telomeres are long during fetal development and how cancer cells reactivate telomerase in cells that have short telomeres. In addition to TPE-OLD, in proliferating stem cells such as activated T-lymphocytes, telomerase can be reversibly activated and silenced by telomere looping. In telomerase positive cancer cells that are induced to differentiate and downregulate telomerase, telomere looping correlates with silencing of the hTERT gene. These studies and others support a role of telomeres in regulating gene expression via telomere looping that may involve interactions with internal telomeric sequences (ITS). In addition to telomere looping, TPE-OLD may be one mechanism of how cells time changes in physiology without initiating a DNA damage response.
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Affiliation(s)
- Wanil Kim
- Department of Cell Biology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Jerry W Shay
- Department of Cell Biology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA.
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119
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Diman A, Decottignies A. Genomic origin and nuclear localization of TERRA telomeric repeat-containing RNA: from Darkness to Dawn. FEBS J 2017; 285:1389-1398. [PMID: 29240300 DOI: 10.1111/febs.14363] [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: 10/19/2017] [Revised: 11/10/2017] [Accepted: 12/08/2017] [Indexed: 01/03/2023]
Abstract
Long noncoding RNAs, produced from distinct regions of the chromosomes, are emerging as new key players in several important biological processes. The long noncoding RNAs add a new layer of complexity to cellular regulatory pathways, from transcription to cellular trafficking or chromatin remodeling. More than 25 years ago, the discovery of a transcriptional activity at telomeres of protozoa ended the long-lasting belief that telomeres were transcriptionally silent. Since then, progressively accumulating evidences established that production of TElomeric Repeat-containing RNA (TERRA) was a general feature of eukaryotic cells. Whether TERRA molecules always originate from the telomeres or whether they can be transcribed from internal telomeric repeats as well is however still a matter of debate. Whether TERRA transcripts always localize to telomeres and play similar roles in all eukaryotic cells is also unclear. We review the studies on TERRA localization in the cell, its composition and some aspects of its transcriptional regulation to summarize the current knowledge and controversies about the genomic origin of TERRA, with a focus on human and mouse TERRA.
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Affiliation(s)
- Aurélie Diman
- Genetic & Epigenetic Alterations of Genomes, de Duve Institute, Université catholique de Louvain, Brussels, Belgium
| | - Anabelle Decottignies
- Genetic & Epigenetic Alterations of Genomes, de Duve Institute, Université catholique de Louvain, Brussels, Belgium
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120
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Regulation of human and mouse telomerase genes by genomic contexts and transcription factors during embryonic stem cell differentiation. Sci Rep 2017; 7:16444. [PMID: 29180668 PMCID: PMC5703907 DOI: 10.1038/s41598-017-16764-w] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Accepted: 11/16/2017] [Indexed: 12/14/2022] Open
Abstract
Differential regulation of telomerase reverse transcriptase (TERT) genes contribute to distinct aging and tumorigenic processes in humans and mice. To study TERT regulation, we generated mouse embryonic stem cell (ESC) lines containing single-copy bacterial artificial chromosome (BAC) reporters, covering hTERT and mTERT genes and their neighboring loci, via recombinase-mediated BAC targeting. ESC lines with chimeric BACs, in which two TERT promoters were swapped, were also generated. Using these chromatinized BACs, we showed that hTERT silencing during differentiation to embryoid bodies (EBs) and to fibroblast-like cells was driven by the human-specific genomic context and accompanied by increases of repressive epigenetic marks, H3K9me3 and H3K27me3, near its promoter. Conversely, the mouse genomic context did not repress TERT transcription until late during differentiation. The hTERT promoter was more active than its mouse counterpart when compared in the same genomic contexts. Mutations of E-box and E2F consensus sites at the promoter had little effect on hTERT transcription in ESCs. However, the mutant promoters were rapidly silenced upon EB differentiation, indicating that transcription factors (TFs) bound to these sites were critical in maintaining hTERT transcription during differentiation. Together, our study revealed a dynamic hTERT regulation by chromatin environment and promoter-bound TFs during ESC differentiation.
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121
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Affiliation(s)
- Jerry W Shay
- The University of Texas Southwestern Medical Center, Department of Cell Biology, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA.
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122
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Transcription regulation of CDKN1A (p21/CIP1/WAF1) by TRF2 is epigenetically controlled through the REST repressor complex. Sci Rep 2017; 7:11541. [PMID: 28912501 PMCID: PMC5599563 DOI: 10.1038/s41598-017-11177-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 07/20/2017] [Indexed: 12/13/2022] Open
Abstract
We observed extra-telomeric binding of the telomere repeat binding factor TRF2 within the promoter of the cyclin-dependent kinase CDKNIA (p21/CIP1/WAF1). This result in TRF2 induced transcription repression of p21. Interestingly, p21 repression was through engagement of the REST-coREST-LSD1-repressor complex and altered histone marks at the p21 promoter in a TRF2-dependent fashion. Furthermore, mutational analysis shows p21 repression requires interaction of TRF2 with a p21 promoter G-quadruplex. Physiologically, TRF2-mediated p21 repression attenuated drug-induced activation of cellular DNA damage response by evading G2/M arrest in cancer cells. Together these reveal for the first time role of TRF2 in REST- repressor complex mediated transcription repression.
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123
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Wang Z, Deng Z, Tutton S, Lieberman PM. The Telomeric Response to Viral Infection. Viruses 2017; 9:v9080218. [PMID: 28792463 PMCID: PMC5580475 DOI: 10.3390/v9080218] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2017] [Revised: 08/06/2017] [Accepted: 08/06/2017] [Indexed: 12/16/2022] Open
Abstract
The ends of linear genomes, whether viral or cellular, can elicit potent DNA damage and innate immune signals. DNA viruses entering the nucleus share many features with telomeres in their ability to either suppress or co-opt these pathways. Here, we review some of the common mechanisms that viruses and telomeres use to manage the DNA damage and innate immune response pathways. We highlight recent studies on the role of the telomere repeat-containing RNA (TERRA) in response to viral infection. We discuss how TERRA can be activated through a p53-response element embedded in a retrotransposon-like repeat found in human subtelomeres. We consider how TERRA can function as a danger signal when secreted in extracellular vesicles to induce inflammatory cytokines in neighboring cells. These findings suggest that TERRA may be part of the innate immune response to viral infection, and support the hypothesis that telomeres and viruses utilize common mechanisms to maintain genome integrity and regulate innate immunity.
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Affiliation(s)
- Zhuo Wang
- The Wistar Institute, Philadelphia, PA 19104, USA.
| | - Zhong Deng
- The Wistar Institute, Philadelphia, PA 19104, USA.
| | - Steve Tutton
- The Wistar Institute, Philadelphia, PA 19104, USA.
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124
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Wood ML, Royle NJ. Chromosomally Integrated Human Herpesvirus 6: Models of Viral Genome Release from the Telomere and Impacts on Human Health. Viruses 2017; 9:E184. [PMID: 28704957 PMCID: PMC5537676 DOI: 10.3390/v9070184] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Revised: 06/30/2017] [Accepted: 07/05/2017] [Indexed: 12/11/2022] Open
Abstract
Human herpesvirus 6A and 6B, alongside some other herpesviruses, have the striking capacity to integrate into telomeres, the terminal repeated regions of chromosomes. The chromosomally integrated forms, ciHHV-6A and ciHHV-6B, are proposed to be a state of latency and it has been shown that they can both be inherited if integration occurs in the germ line. The first step in full viral reactivation must be the release of the integrated viral genome from the telomere and here we propose various models of this release involving transcription of the viral genome, replication fork collapse, and t-circle mediated release. In this review, we also discuss the relationship between ciHHV-6 and the telomere carrying the insertion, particularly how the presence and subsequent partial or complete release of the ciHHV-6 genome may affect telomere dynamics and the risk of disease.
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Affiliation(s)
- Michael L Wood
- Department of Genetics, University of Leicester, University Road, Leicester LE1 7RH, UK.
| | - Nicola J Royle
- Department of Genetics, University of Leicester, University Road, Leicester LE1 7RH, UK.
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125
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Liu X, Wang Y, Chang G, Wang F, Wang F, Geng X. Alternative Splicing of hTERT Pre-mRNA: A Potential Strategy for the Regulation of Telomerase Activity. Int J Mol Sci 2017; 18:ijms18030567. [PMID: 28272339 PMCID: PMC5372583 DOI: 10.3390/ijms18030567] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Revised: 02/14/2017] [Accepted: 03/02/2017] [Indexed: 12/11/2022] Open
Abstract
The activation of telomerase is one of the key events in the malignant transition of cells, and the expression of human telomerase reverse transcriptase (hTERT) is indispensable in the process of activating telomerase. The pre-mRNA alternative splicing of hTERT at the post-transcriptional level is one of the mechanisms for the regulation of telomerase activity. Shifts in splicing patterns occur in the development, tumorigenesis, and response to diverse stimuli in a tissue-specific and cell type–specific manner. Despite the regulation of telomerase activity, the alternative splicing of hTERT pre-mRNA may play a role in other cellular functions. Modulating the mode of hTERT pre-mRNA splicing is providing a new precept of therapy for cancer and aging-related diseases. This review focuses on the patterns of hTERT pre-mRNA alternative splicing and their biological functions, describes the potential association between the alternative splicing of hTERT pre-mRNA and telomerase activity, and discusses the possible significance of the alternative splicing of the hTERT pre-mRNA in the diagnosis, therapy, and prognosis of cancer and aging-related diseases.
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Affiliation(s)
- Xuewen Liu
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Tianjin Medical University, Tianjin 300070, China.
- Key Laboratory of Immune Microenvironment and Disease (Ministry of Education), Tianjin Medical University, Tianjin 300070, China.
| | - Yuchuan Wang
- Tianjin Key Laboratory of Ophthalmology and Visual Science, Tianjin Eye Hospital, Tianjin 300070, China.
- Clinical College of Ophthalmology, Tianjin Medical University, Tianjin 300070, China.
| | - Guangming Chang
- Department of Clinical Laboratory, General Hospital, Tianjin Medical University, Tianjin 300070, China.
| | - Feng Wang
- Department of Genetics, Tianjin Medical University, Tianjin 300070, China.
| | - Fei Wang
- Department of Neurology, General Hospital, Tianjin Medical University, Tianjin 300052, China.
| | - Xin Geng
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Tianjin Medical University, Tianjin 300070, China.
- Key Laboratory of Immune Microenvironment and Disease (Ministry of Education), Tianjin Medical University, Tianjin 300070, China.
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