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Izadi M, Sadri N, Abdi A, Serajian S, Jalalei D, Tahmasebi S. Epigenetic biomarkers in aging and longevity: Current and future application. Life Sci 2024; 351:122842. [PMID: 38879158 DOI: 10.1016/j.lfs.2024.122842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 06/06/2024] [Accepted: 06/12/2024] [Indexed: 06/20/2024]
Abstract
The aging process has been one of the most necessary research fields in the current century, and knowing different theories of aging and the role of different genetic, epigenetic, molecular, and environmental modulating factors in increasing the knowledge of aging mechanisms and developing appropriate diagnostic, therapeutic, and preventive ways would be helpful. One of the most conserved signs of aging is epigenetic changes, including DNA methylation, histone modifications, chromatin remodeling, noncoding RNAs, and extracellular RNAs. Numerous biological processes and hallmarks are vital in aging development, but epigenomic alterations are especially notable because of their importance in gene regulation and cellular identity. The mounting evidence points to a possible interaction between age-related epigenomic alterations and other aging hallmarks, like genome instability. To extend a healthy lifespan and possibly reverse some facets of aging and aging-related diseases, it will be crucial to comprehend global and locus-specific epigenomic modifications and recognize corresponding regulators of health and longevity. In the current study, we will aim to discuss the role of epigenomic mechanisms in aging and the most recent developments in epigenetic diagnostic biomarkers, which have the potential to focus efforts on reversing the destructive signs of aging and extending the lifespan.
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Affiliation(s)
- Mehran Izadi
- Department of Infectious and Tropical Diseases, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran; Synapse Laboratory Diagnostic Technologies Accelerator, Tehran, Iran; Department of Research & Technology, Zeenome Longevity Research Institute, Tehran, Iran
| | - Nariman Sadri
- Synapse Laboratory Diagnostic Technologies Accelerator, Tehran, Iran; Department of Research & Technology, Zeenome Longevity Research Institute, Tehran, Iran; School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Amirhossein Abdi
- Synapse Laboratory Diagnostic Technologies Accelerator, Tehran, Iran; Department of Research & Technology, Zeenome Longevity Research Institute, Tehran, Iran; Royan Institute for Stem Cell Biology and Technology, Tehran, Iran
| | - Sahar Serajian
- Synapse Laboratory Diagnostic Technologies Accelerator, Tehran, Iran; Department of Research & Technology, Zeenome Longevity Research Institute, Tehran, Iran; Royan Institute for Stem Cell Biology and Technology, Tehran, Iran
| | - Dorsa Jalalei
- Synapse Laboratory Diagnostic Technologies Accelerator, Tehran, Iran; Department of Research & Technology, Zeenome Longevity Research Institute, Tehran, Iran; School of Pharmacy, Zanjan University of Medical Sciences, Zanjan, Iran
| | - Safa Tahmasebi
- Synapse Laboratory Diagnostic Technologies Accelerator, Tehran, Iran; Department of Research & Technology, Zeenome Longevity Research Institute, Tehran, Iran; Department of Immunology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
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Targeted Long-Read Bisulfite Sequencing Identifies Differences in the TERT Promoter Methylation Profiles between TERT Wild-Type and TERT Mutant Cancer Cells. Cancers (Basel) 2022; 14:cancers14164018. [PMID: 36011010 PMCID: PMC9406525 DOI: 10.3390/cancers14164018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2022] [Revised: 08/06/2022] [Accepted: 08/10/2022] [Indexed: 11/17/2022] Open
Abstract
Background: TERT promoter methylation, located several hundred base pairs upstream of the transcriptional start site, is cancer specific and correlates with increased TERT mRNA expression and poorer patient outcome. Promoter methylation, however, is not mutually exclusive to TERT activating genetic alterations, as predicted for functionally redundant mechanisms. To annotate the altered patterns of TERT promoter methylation and their relationship with gene expression, we applied a Pacific Biosciences-based, long-read, bisulfite-sequencing technology and compared the differences in the methylation marks between wild-type and mutant cancers in an allele-specific manner. Results: We cataloged TERT genetic alterations (i.e., promoter point mutations or structural variations), allele-specific promoter methylation patterns, and allele-specific expression levels in a cohort of 54 cancer cell lines. In heterozygous mutant cell lines, the mutant alleles were significantly less methylated than their silent, mutation-free alleles (p < 0.05). In wild-type cell lines, by contrast, both epialleles were equally methylated to high levels at the TERT distal promoter, but differentially methylated in the proximal regions. ChIP analysis showed that epialleles with the hypomethylated proximal and core promoter were enriched in the active histone mark H3K4me2/3, whereas epialleles that were methylated in those regions were enriched in the repressive histone mark H3K27me3. Decitabine therapy induced biallelic expression in the wild-type cancer cells, whereas the mutant cell lines were unaffected. Conclusions: Long-read bisulfite sequencing analysis revealed differences in the methylation profiles and responses to demethylating agents between TERT wild-type and genetically altered cancer cell lines. The causal relation between TERT promoter methylation and gene expression remains to be established.
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3
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Chebly A, Ropio J, Peloponese JM, Poglio S, Prochazkova-Carlotti M, Cherrier F, Ferrer J, Idrissi Y, Segal-Bendirdjian E, Chouery E, Farra C, Pham-Ledard A, Beylot-Barry M, Philippe Merlio J, Tomb R, Chevret E. Exploring hTERT promoter methylation in cutaneous T-cell lymphomas. Mol Oncol 2021; 16:1931-1946. [PMID: 33715271 PMCID: PMC9067155 DOI: 10.1002/1878-0261.12946] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 02/28/2021] [Accepted: 03/12/2021] [Indexed: 11/11/2022] Open
Abstract
Cutaneous T‐cell lymphomas (CTCLs) are telomerase‐positive tumors expressing hTERT, although neither gene rearrangement/amplification nor promoter hotspot mutations could explain the hTERT re‐expression. As the hTERT promoter is rich in CpG, we investigated the contribution of epigenetic mechanisms in its re‐expression. We analyzed hTERT promoter methylation status in CTCL cells compared with healthy cells. Gene‐specific methylation analyses revealed a common methylation pattern exclusively in tumor cells. This methylation pattern encompassed a hypermethylated distal region from −650 to −150 bp and a hypomethylated proximal region from −150 to +150 bp. Interestingly, the hypermethylated region matches with the recently named TERT hypermethylated oncogenic region (THOR). THOR has been associated with telomerase reactivation in many cancers, but it has so far not been reported in cutaneous lymphomas. Additionally, we assessed the effect of THOR on two histone deacetylase inhibitors (HDACi), romidepsin and vorinostat, both approved for CTCL treatment and a DNA methyltransferase inhibitor (DNMTi) 5‐azacytidine, unapproved for CTCL. Contrary to our expectations, the findings reported herein revealed that THOR methylation is relatively stable under these epigenetic drugs' pressure, whereas these drugs reduced the hTERT gene expression.
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Affiliation(s)
- Alain Chebly
- Univ. Bordeaux, INSERM, BaRITOn, U1053, F-33000, Bordeaux, France.,Saint Joseph University, Faculty of Medicine, Medical Genetics Unit (UGM), Beirut, Lebanon
| | - Joana Ropio
- Univ. Bordeaux, INSERM, BaRITOn, U1053, F-33000, Bordeaux, France.,Porto University, Institute of Biomedical Sciences of Abel Salazar, Instituto de Investigação e Inovação em Saúde, Institute of Molecular Pathology and Immunology (Ipatimup), Cancer Biology group, 4200-465, Porto, Portugal
| | - Jean-Marie Peloponese
- University of Montpellier, CNRS, IRIM-UMR 9004, Research Institute in Infectiology of Montpellier, Montpellier, France
| | - Sandrine Poglio
- Univ. Bordeaux, INSERM, BaRITOn, U1053, F-33000, Bordeaux, France
| | | | | | - Jacky Ferrer
- Univ. Bordeaux, INSERM, BaRITOn, U1053, F-33000, Bordeaux, France
| | - Yamina Idrissi
- Univ. Bordeaux, INSERM, BaRITOn, U1053, F-33000, Bordeaux, France
| | - Evelyne Segal-Bendirdjian
- INSERM, UMR-S 1124, Team: Cellular Homeostasis Cancer and Therapies, Université de Paris, Paris, France
| | - Eliane Chouery
- Saint Joseph University, Faculty of Medicine, Medical Genetics Unit (UGM), Beirut, Lebanon.,Department of Human Genetics, Gilbert and Rose-Marie Chagoury School of Medicine, Lebanese American University, Byblos, Lebanon
| | - Chantal Farra
- Saint Joseph University, Faculty of Medicine, Medical Genetics Unit (UGM), Beirut, Lebanon.,Hotel Dieu de France Medical Center, Faculty of Medicine, Genetics Department, Beirut, Lebanon
| | - Anne Pham-Ledard
- Univ. Bordeaux, INSERM, BaRITOn, U1053, F-33000, Bordeaux, France.,Bordeaux University Hospital Center, Dermatology Department, F-33000, Bordeaux, France
| | - Marie Beylot-Barry
- Univ. Bordeaux, INSERM, BaRITOn, U1053, F-33000, Bordeaux, France.,Bordeaux University Hospital Center, Dermatology Department, F-33000, Bordeaux, France
| | - Jean Philippe Merlio
- Univ. Bordeaux, INSERM, BaRITOn, U1053, F-33000, Bordeaux, France.,Bordeaux University Hospital Center, Tumor Bank and Tumor Biology Laboratory, F-33600, Pessac, France
| | - Roland Tomb
- Saint Joseph University, Faculty of Medicine, Medical Genetics Unit (UGM), Beirut, Lebanon.,Saint Joseph University, Faculty of Medicine, Dermatology Department, Beirut, Lebanon
| | - Edith Chevret
- Univ. Bordeaux, INSERM, BaRITOn, U1053, F-33000, Bordeaux, France
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4
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Zhang F, Wang S, Zhu J. ETS variant transcription factor 5 and c-Myc cooperate in derepressing the human telomerase gene promoter via composite ETS/E-box motifs. J Biol Chem 2020; 295:10062-10075. [PMID: 32518154 DOI: 10.1074/jbc.ra119.012130] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2019] [Revised: 06/04/2020] [Indexed: 12/19/2022] Open
Abstract
The human telomerase gene (hTERT) is repressed in most somatic cells. How transcription factors activate the hTERT promoter in its repressive chromatin environment is unknown. Here, we report that the ETS family protein ETS variant transcription factor 5 (ETV5) mediates epidermal growth factor (EGF)-induced hTERT expression in MCF10A cells. This activation required MYC proto-oncogene bHLH transcription factor (c-Myc) and depended on the chromatin state of the hTERT promoter. Using chromatinized bacterial artificial chromosome (BAC) reporters in human fibroblasts, we found that ETV5 and c-Myc/MYC-associated factor X (MAX) synergistically activate the hTERT promoter via two identical, but inverted, composite Ets/E-box motifs enclosing the core promoter. Mutations of Ets or E-box sites in either DNA motif abolished the activation and reduced or eliminated the synergism. ETV5 and c-Myc facilitated each other's binding to the hTERT promoter. ETV5 bound to the hTERT promoter in both telomerase-negative and -positive cells, but it activated the repressed hTERT promoter and altered histone modifications only in telomerase-negative cells. The synergistic ETV5/c-Myc activation disappeared when hTERT promoter repression became relieved because of the loss of distal regulatory elements in chimeric human/mouse BAC reporters. Our results suggest that the binding of c-Myc and ETS family proteins to the Ets/E-box motifs derepresses the hTERT promoter by inducing an active promoter configuration, providing a mechanistic insight into hTERT activation during tumorigenesis.
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Affiliation(s)
- Fan Zhang
- Department of Pharmaceutical Sciences, Washington State University College of Pharmacy and Pharmaceutical Sciences, Spokane, Washington, USA
| | - Shuwen Wang
- Department of Pharmaceutical Sciences, Washington State University College of Pharmacy and Pharmaceutical Sciences, Spokane, Washington, USA
| | - Jiyue Zhu
- Department of Pharmaceutical Sciences, Washington State University College of Pharmacy and Pharmaceutical Sciences, Spokane, Washington, USA
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5
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Salzberg AC, Harris-Becker A, Popova EY, Keasey N, Loughran TP, Claxton DF, Grigoryev SA. Genome-wide mapping of histone H3K9me2 in acute myeloid leukemia reveals large chromosomal domains associated with massive gene silencing and sites of genome instability. PLoS One 2017; 12:e0173723. [PMID: 28301528 PMCID: PMC5354391 DOI: 10.1371/journal.pone.0173723] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Accepted: 02/24/2017] [Indexed: 01/05/2023] Open
Abstract
A facultative heterochromatin mark, histone H3 lysine 9 dimethylation (H3K9me2), which is mediated by histone methyltransferases G9a/GLP (EHMT2/1), undergoes dramatic rearrangements during myeloid cell differentiation as observed by chromatin imaging. To determine whether these structural transitions also involve genomic repositioning of H3K9me2, we used ChIP-sequencing to map genome-wide topography of H3K9me2 in normal human granulocytes, normal CD34+ hematopoietic progenitors, primary myeloblasts from acute myeloid leukemia (AML) patients, and a model leukemia cell line K562. We observe that H3K9me2 naturally repositions from the previously designated “repressed” chromatin state in hematopoietic progenitors to predominant association with heterochromatin regions in granulocytes. In contrast, AML cells accumulate H3K9me2 on previously undefined large (> 100 Kb) genomic blocks that are enriched with AML-specific single nucleotide variants, sites of chromosomal translocations, and genes downregulated in AML. Specifically, the AML-specific H3K9me2 blocks are enriched with genes regulated by the proto-oncogene ERG that promotes stem cell characteristics. The AML-enriched H3K9me2 blocks (in contrast to the heterochromatin-associated H3K9me2 blocks enriched in granulocytes) are reduced by pharmacological inhibition of the histone methyltransferase G9a/GLP in K562 cells concomitantly with transcriptional activation of ERG and ETS1 oncogenes. Our data suggest that G9a/GLP mediate formation of transient H3K9me2 blocks that are preserved in AML myeloblasts and may lead to an increased rate of AML-specific mutagenesis and chromosomal translocations.
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Affiliation(s)
- Anna C. Salzberg
- Division of Biostatistics and Bioinformatics and Penn State Institute for Personalized Medicine, Hershey, Pennsylvania, United States of America
| | - Abigail Harris-Becker
- Penn State College of Medicine, Dept. Biochemistry & Molecular Biology, H171, Hershey, Pennsylvania, United States of America
| | - Evgenya Y. Popova
- Penn State College of Medicine, Department of Neural and Behavioral Sciences, Hershey, Pennsylvania, United States of America
| | - Nikki Keasey
- Penn State Cancer Institute; Milton S. Hershey Medical Center, 500 University Drive, Hershey, Pennsylvania, United States of America
| | - Thomas P. Loughran
- University of Virginia Cancer Center, Charlottesville, Virginia, United States of America
| | - David F. Claxton
- Penn State Cancer Institute; Milton S. Hershey Medical Center, 500 University Drive, Hershey, Pennsylvania, United States of America
- * E-mail: (SAG); (DFC)
| | - Sergei A. Grigoryev
- Penn State College of Medicine, Dept. Biochemistry & Molecular Biology, H171, Hershey, Pennsylvania, United States of America
- * E-mail: (SAG); (DFC)
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6
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Cheng D, Zhao Y, Wang S, Zhang F, Russo M, McMahon SB, Zhu J. Repression of telomerase gene promoter requires human-specific genomic context and is mediated by multiple HDAC1-containing corepressor complexes. FASEB J 2016; 31:1165-1178. [PMID: 27940549 DOI: 10.1096/fj.201601111r] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Accepted: 11/28/2016] [Indexed: 12/16/2022]
Abstract
The human telomerase reverse transcriptase (hTERT) gene is repressed in most somatic cells, whereas the expression of the mouse mTert gene is widely detected. To understand the mechanisms of this human-specific repression, we constructed bacterial artificial chromosome (BAC) reporters using human and mouse genomic DNAs encompassing the TERT genes and neighboring loci. Upon chromosomal integration, the hTERT, but not the mTert, reporter was stringently repressed in telomerase-negative human cells in a histone deacetylase (HDAC)-dependent manner, replicating the expression of their respective endogenous genes. In chimeric BACs, the mTert promoter became strongly repressed in the human genomic context, but the hTERT promoter was highly active in the mouse genomic context. Furthermore, an unrelated herpes simplex virus-thymidine kinase (HSV-TK) promoter was strongly repressed in the human, but not in the mouse, genomic context. These results demonstrated that the repression of hTERT gene was dictated by distal elements and its chromatin environment. This repression depended on class I HDACs and involved multiple corepressor complexes, including HDAC1/2-containing Sin3B, nucleosome remodeling and histone deacetylase (NuRD), and corepressor of RE1 silencing transcription factor (CoREST) complexes. Together, our data indicate that the lack of telomerase expression in most human somatic cells results from its repressive genomic environment, providing new insight into the mechanism of long-recognized differential telomerase regulation in mammalian species.-Cheng, D., Zhao, Y., Wang, S., Zhang, F., Russo, M., McMahon, S. B., Zhu, J. Repression of telomerase gene promoter requires human-specific genomic context and is mediated by multiple HDAC1-containing corepressor complexes.
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Affiliation(s)
- De Cheng
- Department of Pharmaceutical Sciences, Washington State University College of Pharmacy, Spokane, Washington, USA
| | - Yuanjun Zhao
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA; and
| | - Shuwen Wang
- Department of Pharmaceutical Sciences, Washington State University College of Pharmacy, Spokane, Washington, USA
| | - Fan Zhang
- Department of Pharmaceutical Sciences, Washington State University College of Pharmacy, Spokane, Washington, USA
| | - Mariano Russo
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA; and
| | - Steven B McMahon
- Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Jiyue Zhu
- Department of Pharmaceutical Sciences, Washington State University College of Pharmacy, Spokane, Washington, USA;
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7
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MacNeil DE, Bensoussan HJ, Autexier C. Telomerase Regulation from Beginning to the End. Genes (Basel) 2016; 7:genes7090064. [PMID: 27649246 PMCID: PMC5042394 DOI: 10.3390/genes7090064] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 08/25/2016] [Accepted: 08/26/2016] [Indexed: 12/11/2022] Open
Abstract
The vast body of literature regarding human telomere maintenance is a true testament to the importance of understanding telomere regulation in both normal and diseased states. In this review, our goal was simple: tell the telomerase story from the biogenesis of its parts to its maturity as a complex and function at its site of action, emphasizing new developments and how they contribute to the foundational knowledge of telomerase and telomere biology.
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Affiliation(s)
- Deanna Elise MacNeil
- Bloomfield Centre for Research in Aging, Lady Davis Institute for Medical Research, Jewish General Hospital, 3755 Côte Ste-Catherine Road, Montréal, QC H3T 1E2, Canada.
- Room M-29, Department of Anatomy and Cell Biology, McGill University, 3640 University Street, Montréal, QC H3A 0C7, Canada.
| | - Hélène Jeanne Bensoussan
- Bloomfield Centre for Research in Aging, Lady Davis Institute for Medical Research, Jewish General Hospital, 3755 Côte Ste-Catherine Road, Montréal, QC H3T 1E2, Canada.
- Room M-29, Department of Anatomy and Cell Biology, McGill University, 3640 University Street, Montréal, QC H3A 0C7, Canada.
| | - Chantal Autexier
- Bloomfield Centre for Research in Aging, Lady Davis Institute for Medical Research, Jewish General Hospital, 3755 Côte Ste-Catherine Road, Montréal, QC H3T 1E2, Canada.
- Room M-29, Department of Anatomy and Cell Biology, McGill University, 3640 University Street, Montréal, QC H3A 0C7, Canada.
- Department of Experimental Medicine, McGill University, 1110 Pins Avenue West, Room 101, Montréal, QC H3A 1A3, Canada.
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Ropio J, Merlio JP, Soares P, Chevret E. Telomerase Activation in Hematological Malignancies. Genes (Basel) 2016; 7:genes7090061. [PMID: 27618103 PMCID: PMC5039560 DOI: 10.3390/genes7090061] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 07/15/2016] [Accepted: 07/29/2016] [Indexed: 12/18/2022] Open
Abstract
Telomerase expression and telomere maintenance are critical for cell proliferation and survival, and they play important roles in development and cancer, including hematological malignancies. Transcriptional regulation of the rate-limiting subunit of human telomerase reverse transcriptase gen (hTERT) is a complex process, and unveiling the mechanisms behind its reactivation is an important step for the development of diagnostic and therapeutic applications. Here, we review the main mechanisms of telomerase activation and the associated hematologic malignancies.
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Affiliation(s)
- Joana Ropio
- Cutaneous Lymphoma Oncogenesis Team INSERM U1053 Bordeaux Research in Translational Oncology, Bordeaux University, Bordeaux 33076, France.
- Institute of Biomedical Sciences of Abel Salazar, University of Porto, Porto 4050-313, Portugal.
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto 4200-135, Portugal.
- Institute of Molecular Pathology and Immunology of the University of Porto (Ipatimup)-Cancer Biology, Rua Dr. Roberto Frias, s/n, Porto 4200-465, Portugal.
| | - Jean-Philippe Merlio
- Cutaneous Lymphoma Oncogenesis Team INSERM U1053 Bordeaux Research in Translational Oncology, Bordeaux University, Bordeaux 33076, France.
- Tumor Bank and Tumor Biology Laboratory, University Hospital Center Bordeaux, Pessac 33604, France.
| | - Paula Soares
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto 4200-135, Portugal.
- Institute of Molecular Pathology and Immunology of the University of Porto (Ipatimup)-Cancer Biology, Rua Dr. Roberto Frias, s/n, Porto 4200-465, Portugal.
- Department of Pathology and Oncology, Medical Faculty of Porto University, Porto 4200-319, Portugal.
| | - Edith Chevret
- Cutaneous Lymphoma Oncogenesis Team INSERM U1053 Bordeaux Research in Translational Oncology, Bordeaux University, Bordeaux 33076, France.
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Zhang F, Cheng D, Wang S, Zhu J. Human Specific Regulation of the Telomerase Reverse Transcriptase Gene. Genes (Basel) 2016; 7:genes7070030. [PMID: 27367732 PMCID: PMC4962000 DOI: 10.3390/genes7070030] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Revised: 06/15/2016] [Accepted: 06/17/2016] [Indexed: 12/19/2022] Open
Abstract
Telomerase, regulated primarily by the transcription of its catalytic subunit telomerase reverse transcriptase (TERT), is critical for controlling cell proliferation and tissue homeostasis by maintaining telomere length. Although there is a high conservation between human and mouse TERT genes, the regulation of their transcription is significantly different in these two species. Whereas mTERT expression is widely detected in adult mice, hTERT is expressed at extremely low levels in most adult human tissues and cells. As a result, mice do not exhibit telomere-mediated replicative aging, but telomere shortening is a critical factor of human aging and its stabilization is essential for cancer development in humans. The chromatin environment and epigenetic modifications of the hTERT locus, the binding of transcriptional factors to its promoter, and recruitment of nucleosome modifying complexes all play essential roles in restricting its transcription in different cell types. In this review, we will discuss recent progress in understanding the molecular mechanisms of TERT regulation in human and mouse tissues and cells, and during cancer development.
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Affiliation(s)
- Fan Zhang
- Department of Pharmaceutical Sciences, Washington State University College of Pharmacy, PO Box 1495, Spokane, WA 99210, USA.
| | - De Cheng
- Department of Pharmaceutical Sciences, Washington State University College of Pharmacy, PO Box 1495, Spokane, WA 99210, USA.
| | - Shuwen Wang
- Department of Pharmaceutical Sciences, Washington State University College of Pharmacy, PO Box 1495, Spokane, WA 99210, USA.
| | - Jiyue Zhu
- Department of Pharmaceutical Sciences, Washington State University College of Pharmacy, PO Box 1495, Spokane, WA 99210, USA.
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10
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Cheng D, Zhao Y, Wang S, Jia W, Kang J, Zhu J. Human Telomerase Reverse Transcriptase (hTERT) Transcription Requires Sp1/Sp3 Binding to the Promoter and a Permissive Chromatin Environment. J Biol Chem 2015; 290:30193-203. [PMID: 26487723 DOI: 10.1074/jbc.m115.662221] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Indexed: 12/14/2022] Open
Abstract
The transcription of human telomerase gene hTERT is regulated by transcription factors (TFs), including Sp1 family proteins, and its chromatin environment. To understand its regulation in a relevant chromatin context, we employed bacterial artificial chromosome reporters containing 160 kb of human genomic sequence containing the hTERT gene. Upon chromosomal integration, the bacterial artificial chromosomes recapitulated endogenous hTERT expression, contrary to transient reporters. Sp1/Sp3 expression did not correlate with hTERT promoter activity, and these TFs bound to the hTERT promoters in both telomerase-positive and telomerase-negative cells. Mutation of the proximal GC-box resulted in a dramatic decrease of hTERT promoter activity, and mutations of all five GC-boxes eliminated its transcriptional activity. Neither mutations of GC-boxes nor knockdown of endogenous Sp1 impacted promoter binding by other TFs, including E-box-binding proteins, and histone acetylation and trimethylation of histone H3K9 at the hTERT promoter in telomerase-positive and -negative cells. The result indicated that promoter binding by Sp1/Sp3 was essential, but not a limiting step, for hTERT transcription. hTERT transcription required a permissive chromatin environment. Importantly, our data also revealed different functions of GC-boxes and E-boxes in hTERT regulation; although GC-boxes were essential for promoter activity, factors bound to the E-boxes functioned to de-repress hTERT promoter.
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Affiliation(s)
- De Cheng
- From the Department of Pharmaceutical Sciences, Washington State University College of Pharmacy, Spokane, Washington 99210
| | - Yuanjun Zhao
- the Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033, and
| | - Shuwen Wang
- From the Department of Pharmaceutical Sciences, Washington State University College of Pharmacy, Spokane, Washington 99210
| | - Wenwen Jia
- the School of Life Sciences and Technology, Tongji University, Shanghai 200092, China
| | - Jiuhong Kang
- the School of Life Sciences and Technology, Tongji University, Shanghai 200092, China
| | - Jiyue Zhu
- From the Department of Pharmaceutical Sciences, Washington State University College of Pharmacy, Spokane, Washington 99210, the Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033, and
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11
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Novak R, Hart K, Mathies RA. Single cell measurement of telomerase expression and splicing using microfluidic emulsion cultures. Nucleic Acids Res 2015. [PMID: 26202962 PMCID: PMC4652743 DOI: 10.1093/nar/gkv477] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Telomerase is a reverse transcriptase that maintains telomeres on the ends of chromosomes, allowing rapidly dividing cells to proliferate while avoiding senescence and apoptosis. Understanding telomerase gene expression and splicing at the single cell level could yield insights into the roles of telomerase during normal cell growth as well as cancer development. Here we use droplet-based single cell culture followed by single cell or colony transcript abundance analysis to investigate the relationship between cell growth and transcript abundance of the telomerase genes encoding the RNA component (hTR) and protein component (hTERT) as well as hTERT splicing. Jurkat and K562 cells were examined under normal cell culture conditions and during exposure to curcumin, a natural compound with anti-carcinogenic and telomerase activity-reducing properties. Individual cells predominantly express single hTERT splice variants, with the α+/β− variant exhibiting significant transcript abundance bimodality that is sustained through cell division. Sub-lethal curcumin exposure results in reduced bimodality of all hTERT splice variants and significant upregulation of alpha splicing, suggesting a possible role in cellular stress response. The single cell culture and transcript abundance analysis method presented here provides the tools necessary for multiparameter single cell analysis which will be critical for understanding phenotypes of heterogeneous cell populations, disease cell populations and their drug response.
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Affiliation(s)
- Richard Novak
- UCSF/UC Berkeley Graduate Program in Bioengineering, University of California, Berkeley, CA 94720, USA
| | - Kristina Hart
- Department of Chemistry, University of California, Berkeley, CA 94720, USA
| | - Richard A Mathies
- UCSF/UC Berkeley Graduate Program in Bioengineering, University of California, Berkeley, CA 94720, USA Department of Chemistry, University of California, Berkeley, CA 94720, USA
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12
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Chilton WL, Marques FZ, West J, Kannourakis G, Berzins SP, O’Brien BJ, Charchar FJ. Acute exercise leads to regulation of telomere-associated genes and microRNA expression in immune cells. PLoS One 2014; 9:e92088. [PMID: 24752326 PMCID: PMC3994003 DOI: 10.1371/journal.pone.0092088] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Accepted: 02/17/2014] [Indexed: 01/05/2023] Open
Abstract
Telomeres are specialized nucleoprotein structures that protect chromosomal ends from degradation. These structures progressively shorten during cellular division and can signal replicative senescence below a critical length. Telomere length is predominantly maintained by the enzyme telomerase. Significant decreases in telomere length and telomerase activity are associated with a host of chronic diseases; conversely their maintenance underpins the optimal function of the adaptive immune system. Habitual physical activity is associated with longer leukocyte telomere length; however, the precise mechanisms are unclear. Potential hypotheses include regulation of telomeric gene transcription and/or microRNAs (miRNAs). We investigated the acute exercise-induced response of telomeric genes and miRNAs in twenty-two healthy males (mean age = 24.1±1.55 years). Participants undertook 30 minutes of treadmill running at 80% of peak oxygen uptake. Blood samples were taken before exercise, immediately post-exercise and 60 minutes post-exercise. Total RNA from white blood cells was submitted to miRNA arrays and telomere extension mRNA array. Results were individually validated in white blood cells and sorted T cell lymphocyte subsets using quantitative real-time PCR (qPCR). Telomerase reverse transcriptase (TERT) mRNA (P = 0.001) and sirtuin-6 (SIRT6) (P<0.05) mRNA expression were upregulated in white blood cells after exercise. Fifty-six miRNAs were also differentially regulated post-exercise (FDR <0.05). In silico analysis identified four miRNAs (miR-186, miR-181, miR-15a and miR-96) that potentially targeted telomeric gene mRNA. The four miRNAs exhibited significant upregulation 60 minutes post-exercise (P<0.001). Telomeric repeat binding factor 2, interacting protein (TERF2IP) was identified as a potential binding target for miR-186 and miR-96 and demonstrated concomitant downregulation (P<0.01) at the corresponding time point. Intense cardiorespiratory exercise was sufficient to differentially regulate key telomeric genes and miRNAs in white blood cells. These results may provide a mechanistic insight into telomere homeostasis and improved immune function and physical health.
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Affiliation(s)
- Warrick L. Chilton
- School of Health Sciences, Federation University Australia, Victoria, Australia
| | - Francine Z. Marques
- School of Health Sciences, Federation University Australia, Victoria, Australia
| | - Jenny West
- Fiona Elsey Cancer Research Institute, Ballarat, Victoria, Australia
| | | | - Stuart P. Berzins
- Fiona Elsey Cancer Research Institute, Ballarat, Victoria, Australia
| | - Brendan J. O’Brien
- School of Health Sciences, Federation University Australia, Victoria, Australia
| | - Fadi J. Charchar
- School of Health Sciences, Federation University Australia, Victoria, Australia
- * E-mail:
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13
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Li J, Ohliger J, Pei M. Significance of epigenetic landscape in cartilage regeneration from the cartilage development and pathology perspective. Stem Cells Dev 2014; 23:1178-94. [PMID: 24555773 DOI: 10.1089/scd.2014.0002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Regenerative therapies for cartilage defects have been greatly advanced by progress in both the stem cell biology and tissue engineering fields. Despite notable successes, significant barriers remain including shortage of autologous cell sources and generation of a stable chondrocyte phenotype using progenitor cells. Increasing demands for the treatment of degenerative diseases, such as osteoarthritis and rheumatoid arthritis, highlight the importance of epigenetic remodeling in cartilage regeneration. Epigenetic regulatory mechanisms, such as microRNAs, DNA methylation, and histone modifications, have been intensively studied due to their direct regulatory role on gene expression. However, a thorough understanding of the environmental factors that initiate these epigenetic events may provide greater insight into the prevention of degenerative diseases and improve the efficacy of treatments. In other words, if we could identify a specific factor from the environment and its downstream signaling events, then we could stop or retard degradation and enhance cartilage regeneration. A more operational definition of epigenetic remodeling has recently been proposed by categorizing the signals during the epigenetic process into epigenators, initiators, and maintainers. This review seeks to compile and reorganize the existing literature pertaining to epigenetic remodeling events placing emphasis on perceiving the landscape of epigenetic mechanisms during cartilage regeneration with the new operational definition, especially from the environmental factors' point of view. Progress in understanding epigenetic regulatory mechanisms could benefit cartilage regeneration and engineering on a larger scale and provide more promising therapeutic applications.
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Affiliation(s)
- Jingting Li
- 1 Stem Cell and Tissue Engineering Laboratory, Department of Orthopaedics, West Virginia University , Morgantown, West Virginia
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Wahlström T, Belikov S, Arsenian Henriksson M. Chromatin dynamics at the hTERT promoter during transcriptional activation and repression by c-Myc and Mnt in Xenopus leavis oocytes. Exp Cell Res 2013; 319:3160-9. [PMID: 23860446 DOI: 10.1016/j.yexcr.2013.07.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 07/03/2013] [Accepted: 07/05/2013] [Indexed: 12/22/2022]
Abstract
The transcription factors c-Myc and Mnt regulate gene expression through dimerization with Max and binding to E-boxes in target genes. While c-Myc activates gene expression via recruitment of histone modifying complexes, Mnt acts as a transcriptional repressor. Here, we used the Xenopus leavis oocyte system to address the effect of c-Myc and Mnt on transcription and chromatin remodeling over the E-box region in the human telomerase reverse transcriptase (hTERT) promoter. As expected we found elevated and decreased levels of hTERT transcription upon exogenously expressed c-Myc/Max and Mnt/Max, respectively. In addition, we confirmed binding of these heterodimers to both E-boxes already enriched with H3K9ac and H4K16ac. These chromatin marks were further enhanced upon c-Myc/Max binding followed by increased DNA accessibility in the E-box region. In contrast, Mnt/Max inhibited Myc-induced transcription and mediated repression through complete chromatin condensation and deacetylation of H3K9 and H4K16 across the E-box region. Importantly, Mnt was able to counteract c-Myc mediated activation even when expressed at low levels, suggesting Mnt to act as a strong repressor by closing the chromatin structure. Collectively our data demonstrate that the balance between c-Myc and Mnt activity determines the transcriptional outcome of the hTERT promoter by modulation of the chromatin architecture.
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Affiliation(s)
- Therese Wahlström
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Box 280, SE-171 77 Stockholm, Sweden
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15
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Sui X, Kong N, Wang Z, Pan H. Epigenetic regulation of the human telomerase reverse transciptase gene: A potential therapeutic target for the treatment of leukemia (Review). Oncol Lett 2013; 6:317-322. [PMID: 24137323 PMCID: PMC3789043 DOI: 10.3892/ol.2013.1367] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Accepted: 05/17/2013] [Indexed: 12/21/2022] Open
Abstract
Telomerase activation is a critical step in human carcinogenesis through the maintenance of telomeres. Telomerase activity is primarily regulated by the human telomerase reverse transcriptase gene (hTERT), thus, an improved understanding of the transcriptional control of hTERT may provide potential therapeutic targets for the treatment of leukemia and other forms of cancer. Epigenetic modulation, a significant regulatory process in cell biology, has recently been shown to be involved in the regulation of the hTERT gene. Moreover, several epigenetic modifiers, including DNA methyltransferase (DNMT) and histone deacetylase (HDAC) inhibitors, are now in pre- and early clinical trials of leukemia as monotherapies or in combination with other drugs, and have achieved significant clinical success. In the present review, the epigenetic mechanisms associated with telomerase activity in leukemia, and the therapeutic potential of an antitelomerase strategy that combines epigenetic modifiers with telomerase hTR subunit small molecule inhibitors are discussed.
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Affiliation(s)
- Xinbing Sui
- Department of Medical Oncology, Sir Run Run Shaw Hospital, Zhejiang University, P.R. China
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Li CT, Hsiao YM, Wu TC, Lin YW, Yeh KT, Ko JL. Vorinostat, SAHA, represses telomerase activity via epigenetic regulation of telomerase reverse transcriptase in non-small cell lung cancer cells. J Cell Biochem 2011; 112:3044-53. [DOI: 10.1002/jcb.23229] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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17
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Higuchi A, Ling QD, Ko YA, Chang Y, Umezawa A. Biomaterials for the feeder-free culture of human embryonic stem cells and induced pluripotent stem cells. Chem Rev 2011; 111:3021-35. [PMID: 21344932 DOI: 10.1021/cr1003612] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Akon Higuchi
- Department of Chemical and Materials Engineering, National Central University, Jhongli, Taoyuan, 32001 Taiwan.
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Liu JP, Chen SM, Cong YS, Nicholls C, Zhou SF, Tao ZZ, Li H. Regulation of telomerase activity by apparently opposing elements. Ageing Res Rev 2010; 9:245-56. [PMID: 20362078 DOI: 10.1016/j.arr.2010.03.002] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2010] [Revised: 03/22/2010] [Accepted: 03/23/2010] [Indexed: 01/08/2023]
Abstract
Telomeres, the ends of chromosomes, undergo frequent remodeling events that are important in cell development, proliferation and differentiation, and neoplastic immortalization. It is not known how the cellular environment influences telomere remodeling, stability, and lengthening or shortening. Telomerase is a ribonucleoprotein complex that maintains and lengthens telomeres in the majority of cancers. Recent studies indicate that a number of factors, including hormones, cytokines, ligands of nuclear receptor, vitamins and herbal extracts have significantly influence telomerase activity and, in some instances, the remodeling of telomeres. This review summarizes the advances in understanding of the positive and negative regulation by extracellular factors of telomerase activity in cancer, stem cells and other systems in mammals.
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Affiliation(s)
- Jun-Ping Liu
- Molecular Signaling Laboratory, Department of Immunology, Central Clinical School, Monash University, Alfred Medical Research and Education Precinct (AMREP), Commercial Road, Melbourne, Victoria 3004, Australia
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