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Jahan J, Joshi S, Oca IMD, Toelle A, Lopez-Yang C, Chacon CV, Beyer AM, Garcia CA, Jarajapu YP. The role of telomerase reverse transcriptase in the mitochondrial protective functions of Angiotensin-(1-7) in diabetic CD34 + cells. Biochem Pharmacol 2024; 222:116109. [PMID: 38458330 PMCID: PMC11007670 DOI: 10.1016/j.bcp.2024.116109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 01/08/2024] [Accepted: 03/05/2024] [Indexed: 03/10/2024]
Abstract
Angiotensin (Ang)-(1-7) stimulates vasoprotective functions of diabetic (DB) CD34+ hematopoietic stem/progenitor cells partly by decreasing reactive oxygen species (ROS), increasing nitric oxide (NO) levels and decreasing TGFβ1 secretion. Telomerase reverse transcriptase (TERT) translocates to mitochondria and regulates ROS generation. Alternative splicing of TERT results in variants α-, β- and α-β-TERT, which may oppose functions of full-length (FL) TERT. This study tested if the protective functions of Ang-(1-7) or TGFβ1-silencing are mediated by mitoTERT and that diabetes decreases FL-TERT expression by inducing splicing. CD34+ cells were isolated from the peripheral blood mononuclear cells of nondiabetic (ND, n = 68) or DB (n = 74) subjects. NO and mitoROS levels were evaluated by flow cytometry. TERT splice variants and mitoDNA-lesions were characterized by qPCR. TRAP assay was used for telomerase activity. Decoy peptide was used to block mitochondrial translocation (mitoXTERT). TERT inhibitor or mitoXTERT prevented the effects of Ang-(1-7) on NO or mitoROS levels in DB-CD34+ cells. FL-TERT expression and telomerase activity were lower and mitoDNA-lesions were higher in DB cells compared to ND and were reversed by Ang-(1-7) or TGFβ1-silencing. The prevalence of TERT splice variants, with predominant β-TERT expression, was higher and the expression of FL-TERT was lower in DB cells (n = 25) compared to ND (n = 30). Ang-(1-7) or TGFβ1-silencing decreased TERT-splicing and increased FL-TERT. Blocking of β-splicing increased FL-TERT and protected mitoDNA in DB-cells. The findings suggest that diabetes induces TERT-splicing in CD34+ cells and that β-TERT splice variant largely contributes to the mitoDNA oxidative damage.
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Affiliation(s)
- Jesmin Jahan
- Department of Pharmaceutical Sciences, College of Health Professions, North Dakota State University, Fargo, ND, USA
| | - Shrinidh Joshi
- Department of Pharmaceutical Sciences, College of Health Professions, North Dakota State University, Fargo, ND, USA
| | | | - Andrew Toelle
- Department of Pharmaceutical Sciences, College of Health Professions, North Dakota State University, Fargo, ND, USA
| | | | | | - Andreas M Beyer
- Department of Medicine and Physiology, Medical College of Wisconsin, Milwaukee, WI, USA
| | | | - Yagna Pr Jarajapu
- Department of Pharmaceutical Sciences, College of Health Professions, North Dakota State University, Fargo, ND, USA.
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2
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Ait-Aissa K, Norwood-Toro LE, Terwoord J, Young M, Paniagua LA, Hader SN, Hughes WE, Hockenberry JC, Beare JE, Linn J, Kohmoto T, Kim J, Betts DH, LeBlanc AJ, Gutterman DD, Beyer AM. Noncanonical Role of Telomerase in Regulation of Microvascular Redox Environment With Implications for Coronary Artery Disease. FUNCTION (OXFORD, ENGLAND) 2022; 3:zqac043. [PMID: 36168588 PMCID: PMC9508843 DOI: 10.1093/function/zqac043] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Revised: 08/05/2022] [Accepted: 08/11/2022] [Indexed: 01/28/2023]
Abstract
Telomerase reverse transcriptase (TERT) (catalytic subunit of telomerase) is linked to the development of coronary artery disease (CAD); however, whether the role of nuclear vs. mitchondrial actions of TERT is involved is not determined. Dominant-negative TERT splice variants contribute to decreased mitochondrial integrity and promote elevated reactive oxygen species production. We hypothesize that a decrease in mitochondrial TERT would increase mtDNA damage, promoting a pro-oxidative redox environment. The goal of this study is to define whether mitochondrial TERT is sufficient to maintain nitric oxide as the underlying mechanism of flow-mediated dilation by preserving mtDNA integrity.Immunoblots and quantitative polymerase chain reaction were used to show elevated levels of splice variants α- and β-deletion TERT tissue from subjects with and without CAD. Genetic, pharmacological, and molecular tools were used to manipulate TERT localization. Isolated vessel preparations and fluorescence-based quantification of mtH2O2 and NO showed that reduction of TERT in the nucleus increased flow induced NO and decreased mtH2O2 levels, while prevention of mitochondrial import of TERT augmented pathological effects. Further elevated mtDNA damage was observed in tissue from subjects with CAD and initiation of mtDNA repair mechanisms was sufficient to restore NO-mediated dilation in vessels from patients with CAD. The work presented is the first evidence that catalytically active mitochondrial TERT, independent of its nuclear functions, plays a critical physiological role in preserving NO-mediated vasodilation and the balance of mitochondrial to nuclear TERT is fundamentally altered in states of human disease that are driven by increased expression of dominant negative splice variants.
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Affiliation(s)
- K Ait-Aissa
- Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - L E Norwood-Toro
- Department of Medicine, Medical College of Wisconsin, Milwaukee, WI 53226, USA,Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - J Terwoord
- Department of Medicine, Medical College of Wisconsin, Milwaukee, WI 53226, USA,Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - M Young
- Department of Medicine, Medical College of Wisconsin, Milwaukee, WI 53226, USA,Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - L A Paniagua
- Department of Medicine, Medical College of Wisconsin, Milwaukee, WI 53226, USA,Cardiovascular Innovation Institute, University of Louisville, Louisville, KY 40292, USA
| | - S N Hader
- Department of Medicine, Medical College of Wisconsin, Milwaukee, WI 53226, USA,Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - W E Hughes
- Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, USA,Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - J C Hockenberry
- Department of Medicine, Medical College of Wisconsin, Milwaukee, WI 53226, USA,Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - J E Beare
- Cardiovascular Innovation Institute, University of Louisville, Louisville, KY 40292, USA,Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, KY 40292, USA
| | - J Linn
- Department of Medicine, Medical College of Wisconsin, Milwaukee, WI 53226, USA,Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - T Kohmoto
- Department of Surgery, Division of Cardiothoracic Surgery, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - J Kim
- Department of Physiology and Pharmacology, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, ON N6A 5C1, Canada
| | - D H Betts
- Department of Physiology and Pharmacology, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, ON N6A 5C1, Canada
| | - A J LeBlanc
- Cardiovascular Innovation Institute, University of Louisville, Louisville, KY 40292, USA,Department of Cardiovascular and Thoracic Surgery, School of Medicine, University of Louisville, Louisville, KY 40292, USA
| | - D D Gutterman
- Department of Medicine, Medical College of Wisconsin, Milwaukee, WI 53226, USA,Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - A M Beyer
- Address correspondence to A.M.B. (e-mail: )
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Montero‐Conde C, Leandro‐García LJ, Martínez‐Montes ÁM, Martínez P, Moya FJ, Letón R, Gil E, Martínez‐Puente N, Guadalix S, Currás‐Freixes M, García‐Tobar L, Zafon C, Jordà M, Riesco‐Eizaguirre G, González‐García P, Monteagudo M, Torres‐Pérez R, Mancikova V, Ruiz‐Llorente S, Pérez‐Martínez M, Pita G, Galofré JC, Gonzalez‐Neira A, Cascón A, Rodríguez‐Antona C, Megías D, Blasco MA, Caleiras E, Rodríguez‐Perales S, Robledo M. Comprehensive molecular analysis of immortalization hallmarks in thyroid cancer reveals new prognostic markers. Clin Transl Med 2022; 12:e1001. [PMID: 35979662 PMCID: PMC9386325 DOI: 10.1002/ctm2.1001] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Revised: 07/08/2022] [Accepted: 07/12/2022] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Comprehensive molecular studies on tumours are needed to delineate immortalization process steps and identify sensitive prognostic biomarkers in thyroid cancer. METHODS AND RESULTS In this study, we extensively characterize telomere-related alterations in a series of 106 thyroid tumours with heterogeneous clinical outcomes. Using a custom-designed RNA-seq panel, we identified five telomerase holoenzyme-complex genes upregulated in clinically aggressive tumours compared to tumours from long-term disease-free patients, being TERT and TERC denoted as independent prognostic markers by multivariate regression model analysis. Characterization of alterations related to TERT re-expression revealed that promoter mutations, methylation and/or copy gains exclusively co-occurred in clinically aggressive tumours. Quantitative-FISH (fluorescence in situ hybridization) analysis of telomere lengths showed a significant shortening in these carcinomas, which matched with a high proliferative rate measured by Ki-67 immunohistochemistry. RNA-seq data analysis indicated that short-telomere tumours exhibit an increased transcriptional activity in the 5-Mb-subtelomeric regions, site of several telomerase-complex genes. Gene upregulation enrichment was significant for specific chromosome-ends such as the 5p, where TERT is located. Co-FISH analysis of 5p-end and TERT loci showed a more relaxed chromatin configuration in short telomere-length tumours compared to normal telomere-length tumours. CONCLUSIONS Overall, our findings support that telomere shortening leads to a 5p subtelomeric region reorganization, facilitating the transcription and accumulation of alterations at TERT-locus.
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Wormald BW, Moser N, deSouza NM, Mantikas KT, Malpartida-Cardenas K, Pennisi I, Ind TEJ, Vroobel K, Kalofonou M, Rodriguez-Manzano J, Georgiou P. Lab-on-chip assay of tumour markers and human papilloma virus for cervical cancer detection at the point-of-care. Sci Rep 2022; 12:8750. [PMID: 35610285 PMCID: PMC9128326 DOI: 10.1038/s41598-022-12557-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 04/22/2022] [Indexed: 01/17/2023] Open
Abstract
Cervical cancer affects over half a million people worldwide each year, the majority of whom are in resource-limited settings where cytology screening is not available. As persistent human papilloma virus (HPV) infections are a key causative factor, detection of HPV strains now complements cytology where screening services exist. This work demonstrates the efficacy of a handheld Lab-on-Chip (LoC) device, with an external sample extraction process, in detecting cervical cancer from biopsy samples. The device is based on Ion-Sensitive Field-Effect Transistor (ISFET) sensors used in combination with loop-mediated isothermal amplification (LAMP) assays, to amplify HPV DNA and human telomerase reverse transcriptase (hTERT) mRNA. These markers were selected because of their high levels of expression in cervical cancer cells, but low to nil expression in normal cervical tissue. The achieved analytical sensitivity for the molecular targets resolved down to a single copy per reaction for the mRNA markers, achieving a limit of detection of 102 for hTERT. In the tissue samples, HPV-16 DNA was present in 4/5 malignant and 2/5 benign tissues, with HPV-18 DNA being present in 1/5 malignant and 1/5 benign tissues. hTERT mRNA was detected in all malignant and no benign tissues, with the demonstrated pilot data to indicate the potential for using the LoC in cervical cancer screening in resource-limited settings on a large scale.
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Affiliation(s)
- Benjamin W Wormald
- Cancer Research UK Cancer Imaging Centre, Division of Radiotherapy and Imaging, Institute of Cancer Research, London, SW7 3RP, UK
| | - Nicolas Moser
- Centre for Bio-Inspired Technology, Department of Electrical and Electronic Engineering, Imperial College London, London, SW7 2BT, UK
| | - Nandita M deSouza
- Cancer Research UK Cancer Imaging Centre, Division of Radiotherapy and Imaging, Institute of Cancer Research, London, SW7 3RP, UK
| | - Katerina-Theresa Mantikas
- Centre for Bio-Inspired Technology, Department of Electrical and Electronic Engineering, Imperial College London, London, SW7 2BT, UK
| | - Kenny Malpartida-Cardenas
- Centre for Bio-Inspired Technology, Department of Electrical and Electronic Engineering, Imperial College London, London, SW7 2BT, UK
| | - Ivana Pennisi
- Department of Infectious Disease, Imperial College London, School of Medicine, St Mary's Hospital, London, W2 1NY, UK
| | - Thomas E J Ind
- Department of Surgical Oncology, Royal Marsden NHS Foundation Trust, London, SW3 6JJ, UK
| | - Katherine Vroobel
- Department of Pathology, Royal Marsden NHS Foundation Trust, London, SW3 6JJ, UK
| | - Melpomeni Kalofonou
- Centre for Bio-Inspired Technology, Department of Electrical and Electronic Engineering, Imperial College London, London, SW7 2BT, UK
| | - Jesus Rodriguez-Manzano
- Department of Infectious Disease, Imperial College London, School of Medicine, St Mary's Hospital, London, W2 1NY, UK
| | - Pantelis Georgiou
- Centre for Bio-Inspired Technology, Department of Electrical and Electronic Engineering, Imperial College London, London, SW7 2BT, UK.
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Guzonjić A, Sopić M, Ostanek B, Kotur-Stevuljević J. Telomere length as a biomarker of aging and diseases. ARHIV ZA FARMACIJU 2022. [DOI: 10.5937/arhfarm72-36376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
Abstract
As research related to healthspan and lifespan has become a hot topic, the necessity for a reliable and practical biomarker of aging (BoA), which can provide information about mortality and morbidity risk, along with remaining life expectancy, has increased. The chromosome terminus non-coding protective structure that prevents genomic instability is called a telomere. The continual shortening of telomeres, which affects their structure as well as function, is a hallmark of agedness. The aforementioned process is a potential cause of age-related diseases (ARDs), leading to a bad prognosis and a low survival rate, which compromise health and longevity. Hence, studies scrutinizing the BoAs often include telomere length (TL) as a prospective candidate. The results of these studies suggest that TL measurement can only provide an approximate appraisal of the aging rate, and its implementation into clinical practice and routine use as a BoA has many limitations and challenges. Nevertheless, measuring TL while determining other biomarkers can be used to assess biological age. This review focuses on the importance of telomeres in health, senescence, and diseases, as well as on summarizing the results and conclusions of previous studies evaluating TL as a potential BoA.
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Telomeres and Cancer. Life (Basel) 2021; 11:life11121405. [PMID: 34947936 PMCID: PMC8704776 DOI: 10.3390/life11121405] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 12/01/2021] [Accepted: 12/06/2021] [Indexed: 12/18/2022] Open
Abstract
Telomeres cap the ends of eukaryotic chromosomes and are indispensable chromatin structures for genome protection and replication. Telomere length maintenance has been attributed to several functional modulators, including telomerase, the shelterin complex, and the CST complex, synergizing with DNA replication, repair, and the RNA metabolism pathway components. As dysfunctional telomere maintenance and telomerase activation are associated with several human diseases, including cancer, the molecular mechanisms behind telomere length regulation and protection need particular emphasis. Cancer cells exhibit telomerase activation, enabling replicative immortality. Telomerase reverse transcriptase (TERT) activation is involved in cancer development through diverse activities other than mediating telomere elongation. This review describes the telomere functions, the role of functional modulators, the implications in cancer development, and the future therapeutic opportunities.
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7
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Gruber HJ, Semeraro MD, Renner W, Herrmann M. Telomeres and Age-Related Diseases. Biomedicines 2021; 9:biomedicines9101335. [PMID: 34680452 PMCID: PMC8533433 DOI: 10.3390/biomedicines9101335] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 09/20/2021] [Accepted: 09/23/2021] [Indexed: 12/24/2022] Open
Abstract
Telomeres are at the non-coding ends of linear chromosomes. Through a complex 3-dimensional structure, they protect the coding DNA and ensure appropriate separation of chromosomes. Aging is characterized by a progressive shortening of telomeres, which compromises their structure and function. Because of their protective function for genomic DNA, telomeres appear to play an important role in the development and progression of many age-related diseases, such as cardiovascular disease (CVD), malignancies, dementia, and osteoporosis. Despite substantial evidence that links telomere length with these conditions, the nature of these observations remains insufficiently understood. Therefore, future studies should address the question of causality. Furthermore, analytical methods should be further improved with the aim to provide informative and comparable results. This review summarize the actual knowledge of telomere biology and the possible implications of telomere dysfunction for the development and progression of age-related diseases. Furthermore, we provide an overview of analytical techniques for the measurement of telomere length and telomerase activity.
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8
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Telomere associated gene expression as well as TERT protein level and telomerase activity are altered in the ovarian follicles of aged mice. Sci Rep 2021; 11:15569. [PMID: 34330985 PMCID: PMC8324818 DOI: 10.1038/s41598-021-95239-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 07/05/2021] [Indexed: 01/23/2023] Open
Abstract
Telomeres cap the ends of eukaryotic chromosomes to maintain genomic stability and integrity during an organism’s lifespan. The length of telomeres inevitably shortens due to DNA replication, genotoxic agents, and biological aging. A limited number of cell types, e.g., stem cells, germline cells, and early embryos can elongate shortened telomeres via the enzymatic action of telomerase, which is composed of telomerase reverse transcriptase (TERT) and telomerase RNA component (Terc). Additionally, telomere-associated proteins including telomeric repeat binding factor 1 (TRF1) and 2 (TRF2), as well as protection of telomeres 1a (POT1a), bind to telomeres to maintain their structural integrity and length. During ovarian aging in mammals, telomeres progressively shorten, accompanied by fertility loss; however, the molecular mechanism underlying this attrition during follicle development remains unclear. In this study, the primary, secondary, preantral, and antral follicles were obtained either from 6-week-old adult (n = 19) or 52-week-old aged (n = 12) mice. We revealed that the Tert, Terc, Trf1, Trf2, and Pot1a gene expression (P < 0.001) and TERT protein (P < 0.01) levels significantly decreased in certain ovarian follicles of the aged group when compared to those of the adult group. Also, telomerase activity exhibited remarkable changes in the follicles of both groups. Consequently, altered telomere-associated gene expression and reduced TERT protein levels in the follicles of aged mice may be a determinant of telomere shortening during ovarian aging, and infertility appearing in the later decades of reproductive lifespan. Further investigations are required to determine the molecular mechanisms underlying these alterations in the follicles during ovarian aging.
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Sharma S, Mukherjee AK, Roy SS, Bagri S, Lier S, Verma M, Sengupta A, Kumar M, Nesse G, Pandey DP, Chowdhury S. Human telomerase is directly regulated by non-telomeric TRF2-G-quadruplex interaction. Cell Rep 2021; 35:109154. [PMID: 34010660 PMCID: PMC7611063 DOI: 10.1016/j.celrep.2021.109154] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 02/15/2021] [Accepted: 04/28/2021] [Indexed: 12/16/2022] Open
Abstract
Human telomerase reverse transcriptase (hTERT) remains suppressed in most normal somatic cells. Resulting erosion of telomeres leads eventually to replicative senescence. Reactivation of hTERT maintains telomeres and triggers progression of >90% of cancers. However, any direct causal link between telomeres and telomerase regulation remains unclear. Here, we show that the telomere-repeat-binding-factor 2 (TRF2) binds hTERT promoter G-quadruplexes and recruits the polycomb-repressor EZH2/PRC2 complex. This is causal for H3K27 trimethylation at the hTERT promoter and represses hTERT in cancer as well as normal cells. Two highly recurrent hTERT promoter mutations found in many cancers, including ∼83% glioblastoma multiforme, that are known to destabilize hTERT promoter G-quadruplexes, showed loss of TRF2 binding in patient-derived primary glioblastoma multiforme cells. Ligand-induced G-quadruplex stabilization restored TRF2 binding, H3K27-trimethylation, and hTERT re-suppression. These results uncover a mechanism of hTERT regulation through a telomeric factor, implicating telomere-telomerase molecular links important in neoplastic transformation, aging, and regenerative therapy.
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Affiliation(s)
- Shalu Sharma
- Integrative and Functional Biology Unit, CSIR-Institute of Genomics and Integrative Biology, New Delhi 110025, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India; CSIR-Institute of Genomics and Integrative Biology, New Delhi 110025, India
| | - Ananda Kishore Mukherjee
- Integrative and Functional Biology Unit, CSIR-Institute of Genomics and Integrative Biology, New Delhi 110025, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India; CSIR-Institute of Genomics and Integrative Biology, New Delhi 110025, India
| | - Shuvra Shekhar Roy
- Integrative and Functional Biology Unit, CSIR-Institute of Genomics and Integrative Biology, New Delhi 110025, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India; CSIR-Institute of Genomics and Integrative Biology, New Delhi 110025, India
| | - Sulochana Bagri
- Integrative and Functional Biology Unit, CSIR-Institute of Genomics and Integrative Biology, New Delhi 110025, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India; CSIR-Institute of Genomics and Integrative Biology, New Delhi 110025, India
| | - Silje Lier
- Department of Microbiology, Oslo University Hospital, Oslo, Norway; Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Meenakshi Verma
- Integrative and Functional Biology Unit, CSIR-Institute of Genomics and Integrative Biology, New Delhi 110025, India; CSIR-Institute of Genomics and Integrative Biology, New Delhi 110025, India
| | - Antara Sengupta
- Integrative and Functional Biology Unit, CSIR-Institute of Genomics and Integrative Biology, New Delhi 110025, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India; CSIR-Institute of Genomics and Integrative Biology, New Delhi 110025, India
| | - Manish Kumar
- Imaging Facility, CSIR-Institute of Genomics and Integrative Biology, New Delhi 110025, India; CSIR-Institute of Genomics and Integrative Biology, New Delhi 110025, India
| | - Gaute Nesse
- Department of Microbiology, Oslo University Hospital, Oslo, Norway
| | | | - Shantanu Chowdhury
- Integrative and Functional Biology Unit, CSIR-Institute of Genomics and Integrative Biology, New Delhi 110025, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India; GNR Knowledge Centre for Genome and Informatics, CSIR-Institute of Genomics and Integrative Biology, New Delhi 110025, India; CSIR-Institute of Genomics and Integrative Biology, New Delhi 110025, India.
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Plyasova AA, Zhdanov DD. Alternative Splicing of Human Telomerase Reverse Transcriptase (hTERT) and Its Implications in Physiological and Pathological Processes. Biomedicines 2021; 9:526. [PMID: 34065134 PMCID: PMC8150890 DOI: 10.3390/biomedicines9050526] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 05/03/2021] [Accepted: 05/05/2021] [Indexed: 12/24/2022] Open
Abstract
Alternative splicing (AS) of human telomerase catalytic subunit (hTERT, human telomerase reverse transcriptase) pre-mRNA strongly regulates telomerase activity. Several proteins can regulate AS in a cell type-specific manner and determine the functions of cells. In addition to being involved in telomerase activity regulation, AS provides cells with different splice variants that may have alternative biological activities. The modulation of telomerase activity through the induction of hTERT AS is involved in the development of different cancer types and embryos, and the differentiation of stem cells. Regulatory T cells may suppress the proliferation of target human and murine T and B lymphocytes and NK cells in a contact-independent manner involving activation of TERT AS. This review focuses on the mechanism of regulation of hTERT pre-mRNA AS and the involvement of splice variants in physiological and pathological processes.
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Affiliation(s)
| | - Dmitry D. Zhdanov
- Institute of Biomedical Chemistry, Pogodinskaya st 10/8, 119121 Moscow, Russia;
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Jiang X, Zhang X, Ren C, Ruan Y, Lu Y, Yuan L, Li J, Yan A, Wang Y, Luo P, Hu C, Chen T. Interleukin-2 enhancer binding factor 2 (ILF2) in pacific white shrimp (Litopenaeus vannamei): Alternatively spliced isoforms with different responses in the immune defenses against vibrio infection. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2021; 118:103975. [PMID: 33383068 DOI: 10.1016/j.dci.2020.103975] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 12/11/2020] [Accepted: 12/13/2020] [Indexed: 06/12/2023]
Abstract
Alternative splicing is an essential molecular mechanism that increase the protein diversity of a species to regulate important biological processes. As a transcription factor, Interleukin-2 enhancer binding factor 2 (ILF2) regulates the functions of interleukin-2 (IL-2) at the levels of transcription, splicing and translation, and plays other critical roles in the immune system. ILF2 is well-documented in vertebrates, while little is currently known in crustacean species such as the Pacific white shrimp (Litopenaeus vannamei). In the present study, five cDNA for spliced isoforms of Lv-ILF2 were identified, in which four of them are the full-length long isoforms (Lv-ILF2-L1, Lv-ILF2-L2, Lv-ILF2-L3 and Lv-ILF2-L4) and one of them is a truncated short isoform (Lv-ILF2-S). The whole sequence of ILF2 gene from L. vannamei was obtained, which is 11,680 bp in length with 9 exons separated by 8 introns. All five isoforms contain a domain associated with zinc fingers (DZF). Two alternative splicing types (alternative 5' splice site and alternative 3' splice site) were identified in the five isoforms. The Lv-ILF2 mRNA showed a broad distribution in all detected tissues, and the Lv-ILF2-L transcript levels were higher than those of Lv-ILF2-S in corresponding tissues. The mRNA levels of Lv-ILF2-S in the hepatopancreas, heart, muscle and stomach, but not in the eyestalk, were significantly increased after challenges with Vibrio harveyi or lipopolysaccharide (LPS), while no significant changes were observed for the transcript levels of Lv-ILF2-L in these tissues under the same immune stimulants. On the contrary, the transcript levels of neither Lv-ILF2-S nor Lv-ILF2-L were affected by challenges of polyinosinic: polycytidylic acid [Poly (I:C)]. In addition, after knockdown of the Lv-ILF2 mRNA level by siRNA, the mortality of shrimp and the hepatopancreatic bacterial numbers were significantly increased under V. harveyi challenge, indicating that Lv-ILF2 might participate in the immune defenses against V. harveyi invasion. Collectively, our study here supplied the first evidence for a novel splicing mechanism of ILF2 transcripts, and provided a functional link between the Lv-ILF2 isoforms and the capacity against pathogenic Vibrio in penaeid shrimp.
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Affiliation(s)
- Xiao Jiang
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology (LMB), Guangdong Provincial Key Laboratory of Applied Marine Biology (LAMB), South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China; Institution of South China Sea Ecology and Environmental Engineering (ISEE), Chinese Academy of Sciences, Guangzhou, China
| | - Xin Zhang
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology (LMB), Guangdong Provincial Key Laboratory of Applied Marine Biology (LAMB), South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China; University of Chinese Academy of Sciences, Beijing, China
| | - Chunhua Ren
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology (LMB), Guangdong Provincial Key Laboratory of Applied Marine Biology (LAMB), South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China; Institution of South China Sea Ecology and Environmental Engineering (ISEE), Chinese Academy of Sciences, Guangzhou, China
| | - Yao Ruan
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology (LMB), Guangdong Provincial Key Laboratory of Applied Marine Biology (LAMB), South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China; University of Chinese Academy of Sciences, Beijing, China
| | - Yongtong Lu
- Guangdong Province Key Laboratory for Biotechnology Drug Candidates, School of Life Sciences and Biopharmaceutics, Guangdong Pharmaceutical University, Guangzhou, China
| | - Lihong Yuan
- Guangdong Province Key Laboratory for Biotechnology Drug Candidates, School of Life Sciences and Biopharmaceutics, Guangdong Pharmaceutical University, Guangzhou, China
| | - Jiaxi Li
- School of Stomatology and Medicine, School of Life Science and Engineering, Foshan University, Foshan, China
| | - Aifen Yan
- School of Stomatology and Medicine, School of Life Science and Engineering, Foshan University, Foshan, China
| | - Yanhong Wang
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology (LMB), Guangdong Provincial Key Laboratory of Applied Marine Biology (LAMB), South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China; Institution of South China Sea Ecology and Environmental Engineering (ISEE), Chinese Academy of Sciences, Guangzhou, China
| | - Peng Luo
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology (LMB), Guangdong Provincial Key Laboratory of Applied Marine Biology (LAMB), South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China; Institution of South China Sea Ecology and Environmental Engineering (ISEE), Chinese Academy of Sciences, Guangzhou, China.
| | - Chaoqun Hu
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology (LMB), Guangdong Provincial Key Laboratory of Applied Marine Biology (LAMB), South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China; Institution of South China Sea Ecology and Environmental Engineering (ISEE), Chinese Academy of Sciences, Guangzhou, China.
| | - Ting Chen
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology (LMB), Guangdong Provincial Key Laboratory of Applied Marine Biology (LAMB), South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China; Institution of South China Sea Ecology and Environmental Engineering (ISEE), Chinese Academy of Sciences, Guangzhou, China.
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12
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Hossain KA, Jurkowski M, Czub J, Kogut M. Mechanism of recognition of parallel G-quadruplexes by DEAH/RHAU helicase DHX36 explored by molecular dynamics simulations. Comput Struct Biotechnol J 2021; 19:2526-2536. [PMID: 34025941 PMCID: PMC8114077 DOI: 10.1016/j.csbj.2021.04.039] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 04/14/2021] [Accepted: 04/16/2021] [Indexed: 02/07/2023] Open
Abstract
Because of high stability and slow unfolding rates of G-quadruplexes (G4), cells have evolved specialized helicases that disrupt these non-canonical DNA and RNA structures in an ATP-dependent manner. One example is DHX36, a DEAH-box helicase, which participates in gene expression and replication by recognizing and unwinding parallel G4s. Here, we studied the molecular basis for the high affinity and specificity of DHX36 for parallel-type G4s using all-atom molecular dynamics simulations. By computing binding free energies, we found that the two main G4-interacting subdomains of DHX36, DSM and OB, separately exhibit high G4 affinity but they act cooperatively to recognize two distinctive features of parallel G4s: the exposed planar face of a guanine tetrad and the unique backbone conformation of a continuous guanine tract, respectively. Our results also show that DSM-mediated interactions are the main contributor to the binding free energy and rely on making extensive van der Waals contacts between the GXXXG motifs and hydrophobic residues of DSM and a flat guanine plane. Accordingly, the sterically more accessible 5'-G-tetrad allows for more favorable van der Waals and hydrophobic interactions which leads to the preferential binding of DSM to the 5'-side. In contrast to DSM, OB binds to G4 mostly through polar interactions by flexibly adapting to the 5'-terminal guanine tract to form a number of strong hydrogen bonds with the backbone phosphate groups. We also identified a third DHX36/G4 interaction site formed by the flexible loop missing in the crystal structure.
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Affiliation(s)
- Kazi Amirul Hossain
- Department of Physical Chemistry, Gdansk University of Technology, ul. Narutowicza 11/12, 80-233 Gdansk, Poland
| | - Michal Jurkowski
- Department of Physical Chemistry, Gdansk University of Technology, ul. Narutowicza 11/12, 80-233 Gdansk, Poland
| | - Jacek Czub
- Department of Physical Chemistry, Gdansk University of Technology, ul. Narutowicza 11/12, 80-233 Gdansk, Poland
| | - Mateusz Kogut
- Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw, Poland
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13
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Dogan F, Forsyth NR. Telomerase Regulation: A Role for Epigenetics. Cancers (Basel) 2021; 13:cancers13061213. [PMID: 33802026 PMCID: PMC8000866 DOI: 10.3390/cancers13061213] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 03/05/2021] [Accepted: 03/07/2021] [Indexed: 12/11/2022] Open
Abstract
Simple Summary Maintenance of telomeres is a fundamental step in human carcinogenesis and is primarily regulated by telomerase and the human telomerase reverse transcriptase gene (TERT). Improved understanding of the transcriptional control of this gene may provide potential therapeutic targets. Epigenetic modifications are a prominent mechanism to control telomerase activity and regulation of the TERT gene. TERT-targeting miRNAs have been widely studied and their function explained through pre-clinical in vivo model-based validation studies. Further, histone deacetylase inhibitors are now in pre and early clinical trials with significant clinical success. Importantly, TERT downregulation through epigenetic modifications including TERT promoter methylation, histone deacetylase inhibitors, and miRNA activity might contribute to clinical study design. This review provides an overview of the epigenetic mechanisms involved in the regulation of TERT expression and telomerase activity. Abstract Telomerase was first described by Greider and Blackburn in 1984, a discovery ultimately recognized by the Nobel Prize committee in 2009. The three decades following on from its discovery have been accompanied by an increased understanding of the fundamental mechanisms of telomerase activity, and its role in telomere biology. Telomerase has a clearly defined role in telomere length maintenance and an established influence on DNA replication, differentiation, survival, development, apoptosis, tumorigenesis, and a further role in therapeutic resistance in human stem and cancer cells including those of breast and cervical origin. TERT encodes the catalytic subunit and rate-limiting factor for telomerase enzyme activity. The mechanisms of activation or silencing of TERT remain open to debate across somatic, cancer, and stem cells. Promoter mutations upstream of TERT may promote dysregulated telomerase activation in tumour cells but additional factors including epigenetic, transcriptional and posttranscriptional modifications also have a role to play. Previous systematic analysis indicated methylation and mutation of the TERT promoter in 53% and 31%, respectively, of TERT expressing cancer cell lines supporting the concept of a key role for epigenetic alteration associated with TERT dysregulation and cellular transformation. Epigenetic regulators including DNA methylation, histone modification, and non-coding RNAs are now emerging as drivers in the regulation of telomeres and telomerase activity. Epigenetic regulation may be responsible for reversible silencing of TERT in several biological processes including development and differentiation, and increased TERT expression in cancers. Understanding the epigenetic mechanisms behind telomerase regulation holds important prospects for cancer treatment, diagnosis and prognosis. This review will focus on the role of epigenetics in telomerase regulation.
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Affiliation(s)
- Fatma Dogan
- The Guy Hilton Research Laboratories, School of Pharmacy and Bioengineering, Faculty of Medicine and Health Sciences, Keele University, Stoke on Trent ST4 7QB, UK;
| | - Nicholas R. Forsyth
- The Guy Hilton Research Laboratories, School of Pharmacy and Bioengineering, Faculty of Medicine and Health Sciences, Keele University, Stoke on Trent ST4 7QB, UK;
- School of Medicine, Tongji University, Shanghai 200092, China
- Correspondence:
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14
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Angarola BL, Anczuków O. Splicing alterations in healthy aging and disease. WILEY INTERDISCIPLINARY REVIEWS. RNA 2021. [PMID: 33565261 DOI: 10.1002/wrna.1643.] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Alternative RNA splicing is a key step in gene expression that allows generation of numerous messenger RNA transcripts encoding proteins of varied functions from the same gene. It is thus a rich source of proteomic and functional diversity. Alterations in alternative RNA splicing are observed both during healthy aging and in a number of human diseases, several of which display premature aging phenotypes or increased incidence with age. Age-associated splicing alterations include differential splicing of genes associated with hallmarks of aging, as well as changes in the levels of core spliceosomal genes and regulatory splicing factors. Here, we review the current known links between alternative RNA splicing, its regulators, healthy biological aging, and diseases associated with aging or aging-like phenotypes. This article is categorized under: RNA in Disease and Development > RNA in Disease RNA Processing > Splicing Regulation/Alternative Splicing.
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Affiliation(s)
| | - Olga Anczuków
- The Jackson Laboratory for Genomic Medicine, Farmington, Connecticut, USA.,Department of Genetics and Genome Sciences, UConn Health, Farmington, Connecticut, USA.,Institute for Systems Genomics, UConn Health, Farmington, Connecticut, USA
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15
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Angarola BL, Anczuków O. Splicing alterations in healthy aging and disease. WILEY INTERDISCIPLINARY REVIEWS-RNA 2021; 12:e1643. [PMID: 33565261 DOI: 10.1002/wrna.1643] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Revised: 01/05/2021] [Accepted: 01/07/2021] [Indexed: 12/19/2022]
Abstract
Alternative RNA splicing is a key step in gene expression that allows generation of numerous messenger RNA transcripts encoding proteins of varied functions from the same gene. It is thus a rich source of proteomic and functional diversity. Alterations in alternative RNA splicing are observed both during healthy aging and in a number of human diseases, several of which display premature aging phenotypes or increased incidence with age. Age-associated splicing alterations include differential splicing of genes associated with hallmarks of aging, as well as changes in the levels of core spliceosomal genes and regulatory splicing factors. Here, we review the current known links between alternative RNA splicing, its regulators, healthy biological aging, and diseases associated with aging or aging-like phenotypes. This article is categorized under: RNA in Disease and Development > RNA in Disease RNA Processing > Splicing Regulation/Alternative Splicing.
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Affiliation(s)
| | - Olga Anczuków
- The Jackson Laboratory for Genomic Medicine, Farmington, Connecticut, USA.,Department of Genetics and Genome Sciences, UConn Health, Farmington, Connecticut, USA.,Institute for Systems Genomics, UConn Health, Farmington, Connecticut, USA
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16
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Xiao W, Chen X, Li X, Deng K, Liu H, Ma J, Wang Z, Hu Y, Hou J. RBM10 regulates human TERT gene splicing and inhibits pancreatic cancer progression. Am J Cancer Res 2021; 11:157-170. [PMID: 33520366 PMCID: PMC7840715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 10/14/2020] [Indexed: 06/12/2023] Open
Abstract
Dysregulation of alternative splicing of hTERT gene to generate full-length Htert (hTERT-FL) that reactivate telomerase has been recognized as a major pathological alteration in pancreatic cancer (PrCa). Mechanism about the factors that regulate hTERT-FL splicing is lacking. Through bioinformatics approach, we focus on a candidate splicing factor RBM10, which leads to a switch in hTERT transcripts to generate a function-less isoform hTERT-s in PrCa, suppressed both telomerase activity and subsequent telomere shortening. RBM10 expression is negatively associated with PrCa progression. Gain or loss of RBM10 also significantly changed PrCa cell proliferation in vitro and in xenografts. RNA-IP and RNA pull-down assays reveal that RBM10 promotes the exclusion of exons7 and 8 which results in the production of TERT-s transcripts. This study may increase knowledge about potentially targetable cancer associated splicing factors and provide novel insights into therapeutic approach in PrCa.
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Affiliation(s)
- Wenjing Xiao
- School of Materials Science and Engineering, Southwest Jiaotong UniversityChengdu 611756, China
- Department of Pharmacy, The General Hospital of Western Theater Command of PLAChengdu 610083, China
| | - Xin Chen
- Department of Laboratory Medicine, The Third People’s Hospital of Chengdu/Affiliated Hospital of Southwest Jiaotong UniversityChengdu 610015, China
| | - Xia Li
- Department of Ultrasound Diagnosis, Women and Children’s Health Care Hospital of LinyiLinyi 276000, China
| | - Kaiwen Deng
- Department of Pharmacy, The General Hospital of Western Theater Command of PLAChengdu 610083, China
| | - Huawei Liu
- Department of Laboratory Medicine, The Third People’s Hospital of Chengdu/Affiliated Hospital of Southwest Jiaotong UniversityChengdu 610015, China
| | - Jie Ma
- Department of Pharmacy, The General Hospital of Western Theater Command of PLAChengdu 610083, China
| | - Zhanhao Wang
- Department of Laboratory Medicine, The Third People’s Hospital of Chengdu/Affiliated Hospital of Southwest Jiaotong UniversityChengdu 610015, China
| | - Yonghe Hu
- School of Materials Science and Engineering, Southwest Jiaotong UniversityChengdu 611756, China
- Department of Pharmacy, The General Hospital of Western Theater Command of PLAChengdu 610083, China
| | - Jun Hou
- Department of Pharmacy, The General Hospital of Western Theater Command of PLAChengdu 610083, China
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17
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Yuan X, Dai M, Xu D. Telomere-related Markers for Cancer. Curr Top Med Chem 2020; 20:410-432. [PMID: 31903880 PMCID: PMC7475940 DOI: 10.2174/1568026620666200106145340] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 12/03/2019] [Accepted: 12/14/2019] [Indexed: 02/06/2023]
Abstract
Telomeres are structurally nucleoprotein complexes at termini of linear chromosomes and essential to chromosome stability/integrity. In normal human cells, telomere length erodes progressively with each round of cell divisions, which serves as an important barrier to uncontrolled proliferation and malignant transformation. In sharp contrast, telomere maintenance is a key feature of human malignant cells and required for their infinite proliferation and maintenance of other cancer hallmarks as well. Thus, a telomere-based anti-cancer strategy has long been suggested. However, clinically efficient and specific drugs targeting cancer telomere-maintenance have still been in their infancy thus far. To achieve this goal, it is highly necessary to elucidate how exactly cancer cells maintain functional telomeres. In the last two decades, numerous studies have provided profound mechanistic insights, and the identified mechanisms include the aberrant activation of telomerase or the alternative lengthening of telomere pathway responsible for telomere elongation, dysregulation and mutation of telomere-associated factors, and other telomere homeostasis-related signaling nodes. In the present review, these various strategies employed by malignant cells to regulate their telomere length, structure and function have been summarized, and potential implications of these findings in the rational development of telomere-based cancer therapy and other clinical applications for precision oncology have been discussed.
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Affiliation(s)
- Xiaotian Yuan
- Center for Reproductive Medicine, Shandong University, Jinan, 250012, China
| | - Mingkai Dai
- Central Research Laboratory, Shandong University Second Hospital, Jinan, 250033, China.,Karolinska Institute Collaborative Laboratory for Cancer and Stem Cell Research, Shandong University Second Hospital, Jinan, 250033, China
| | - Dawei Xu
- Karolinska Institute Collaborative Laboratory for Cancer and Stem Cell Research, Shandong University Second Hospital, Jinan, 250033, China.,Department of Medicine, Division of Hematology, Center for Molecular Medicine (CMM) and Bioclinicum, Karolinska Institute and Karolinska University Hospital Solna, Solna 171 64, Sweden
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18
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Kharel P, Becker G, Tsvetkov V, Ivanov P. Properties and biological impact of RNA G-quadruplexes: from order to turmoil and back. Nucleic Acids Res 2020; 48:12534-12555. [PMID: 33264409 PMCID: PMC7736831 DOI: 10.1093/nar/gkaa1126] [Citation(s) in RCA: 76] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 10/23/2020] [Accepted: 11/06/2020] [Indexed: 12/12/2022] Open
Abstract
Guanine-quadruplexes (G4s) are non-canonical four-stranded structures that can be formed in guanine (G) rich nucleic acid sequences. A great number of G-rich sequences capable of forming G4 structures have been described based on in vitro analysis, and evidence supporting their formation in live cells continues to accumulate. While formation of DNA G4s (dG4s) within chromatin in vivo has been supported by different chemical, imaging and genomic approaches, formation of RNA G4s (rG4s) in vivo remains a matter of discussion. Recent data support the dynamic nature of G4 formation in the transcriptome. Such dynamic fluctuation of rG4 folding-unfolding underpins the biological significance of these structures in the regulation of RNA metabolism. Moreover, rG4-mediated functions may ultimately be connected to mechanisms underlying disease pathologies and, potentially, provide novel options for therapeutics. In this framework, we will review the landscape of rG4s within the transcriptome, focus on their potential impact on biological processes, and consider an emerging connection of these functions in human health and disease.
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Affiliation(s)
- Prakash Kharel
- Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Gertraud Becker
- Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Vladimir Tsvetkov
- Computational Oncology Group, I. M. Sechenov First Moscow State Medical University, Moscow 119146, Russia
- Federal Research and Clinical Center for Physical-Chemical Medicine, Federal Medical Biological Agency, Moscow 119435, Russia
- A. V. Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences, Moscow 117912, Russia
| | - Pavel Ivanov
- Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
- Harvard Initiative for RNA Medicine, Boston, MA 02115, USA
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19
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Schrumpfová PP, Fajkus J. Composition and Function of Telomerase-A Polymerase Associated with the Origin of Eukaryotes. Biomolecules 2020; 10:biom10101425. [PMID: 33050064 PMCID: PMC7658794 DOI: 10.3390/biom10101425] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 09/29/2020] [Accepted: 10/01/2020] [Indexed: 12/19/2022] Open
Abstract
The canonical DNA polymerases involved in the replication of the genome are unable to fully replicate the physical ends of linear chromosomes, called telomeres. Chromosomal termini thus become shortened in each cell cycle. The maintenance of telomeres requires telomerase—a specific RNA-dependent DNA polymerase enzyme complex that carries its own RNA template and adds telomeric repeats to the ends of chromosomes using a reverse transcription mechanism. Both core subunits of telomerase—its catalytic telomerase reverse transcriptase (TERT) subunit and telomerase RNA (TR) component—were identified in quick succession in Tetrahymena more than 30 years ago. Since then, both telomerase subunits have been described in various organisms including yeasts, mammals, birds, reptiles and fish. Despite the fact that telomerase activity in plants was described 25 years ago and the TERT subunit four years later, a genuine plant TR has only recently been identified by our group. In this review, we focus on the structure, composition and function of telomerases. In addition, we discuss the origin and phylogenetic divergence of this unique RNA-dependent DNA polymerase as a witness of early eukaryotic evolution. Specifically, we discuss the latest information regarding the recently discovered TR component in plants, its conservation and its structural features.
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Affiliation(s)
- Petra Procházková Schrumpfová
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kotlářská 2, CZ-61137 Brno, Czech Republic;
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology, Masaryk University, Kamenice 5, CZ-62500 Brno, Czech Republic
- Correspondence:
| | - Jiří Fajkus
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kotlářská 2, CZ-61137 Brno, Czech Republic;
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology, Masaryk University, Kamenice 5, CZ-62500 Brno, Czech Republic
- The Czech Academy of Sciences, Institute of Biophysics, Královopolská 135, 612 65 Brno, Czech Republic
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20
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Yan Z, Shen Z, Li Z, Chao Q, Kong L, Gao ZF, Li QW, Zheng HY, Zhao CF, Lu CM, Wang YW, Wang BC. Genome-wide transcriptome and proteome profiles indicate an active role of alternative splicing during de-etiolation of maize seedlings. PLANTA 2020; 252:60. [PMID: 32964359 DOI: 10.1007/s00425-020-03464-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 09/12/2020] [Indexed: 06/11/2023]
Abstract
AS events affect genes encoding protein domain composition and make the single gene produce more proteins with a certain number of genes to satisfy the establishment of photosynthesis during de-etiolation. The drastic switch from skotomorphogenic to photomorphogenic development is an excellent system to elucidate rapid developmental responses to environmental stimuli in plants. To decipher the effects of different light wavelengths on de-etiolation, we illuminated etiolated maize seedlings with blue, red, blue-red mixed and white light, respectively. We found that blue light alone has the strongest effect on photomorphogenesis and that this effect can be attributed to the higher number and expression levels of photosynthesis and chlorosynthesis proteins. Deep sequencing-based transcriptome analysis revealed gene expression changes under different light treatments and a genome-wide alteration in alternative splicing (AS) profiles. We discovered 41,188 novel transcript isoforms for annotated genes, which increases the percentage of multi-exon genes with AS to 63% in maize. We provide peptide support for all defined types of AS, especially retained introns. Further in silico prediction revealed that 58.2% of retained introns have changes in domains compared with their most similar annotated protein isoform. This suggests that AS acts as a protein function switch allowing rapid light response through the addition or removal of functional domains. The richness of novel transcripts and protein isoforms also demonstrates the potential and importance of integrating proteomics into genome annotation in maize.
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Affiliation(s)
- Zhen Yan
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, No. 20 Nanxincun, Xiangshan, Beijing, 100093, China
- University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Zhuo Shen
- Vegetable Research Institute, Guangdong Academy of Agricultural Sciences, Guangdong Key Laboratory for New Technology Research of Vegetables, Guangzhou, 510640, China
| | - Zhe Li
- Precision Scientific (Beijing) Co., Ltd., Beijing, 100085, China
| | - Qing Chao
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, No. 20 Nanxincun, Xiangshan, Beijing, 100093, China
- University of Chinese Academy of Sciences, 100049, Beijing, China
- The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, 100039, China
| | - Lei Kong
- State Key Laboratory of Protein and Plant Gene Research, Center for Bioinformatics, College of Life Sciences, Peking University, Beijing, 100871, China
| | - Zhi-Fang Gao
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, No. 20 Nanxincun, Xiangshan, Beijing, 100093, China
| | - Qing-Wei Li
- Beijing Botanical Garden, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Hai-Yan Zheng
- Center for Advanced Biotechnology and Medicine, Biological Mass Spectrometry Facility, Rutgers University, Piscataway, NJ, 08855, USA
| | - Cai-Feng Zhao
- Center for Advanced Biotechnology and Medicine, Biological Mass Spectrometry Facility, Rutgers University, Piscataway, NJ, 08855, USA
| | - Cong-Ming Lu
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, 271018, Shandong, China
| | - Ying-Wei Wang
- Beijing Botanical Garden, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China.
| | - Bai-Chen Wang
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, No. 20 Nanxincun, Xiangshan, Beijing, 100093, China.
- University of Chinese Academy of Sciences, 100049, Beijing, China.
- The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, 100039, China.
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21
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Dosset M, Castro A, Carter H, Zanetti M. Telomerase and CD4 T Cell Immunity in Cancer. Cancers (Basel) 2020; 12:cancers12061687. [PMID: 32630460 PMCID: PMC7352225 DOI: 10.3390/cancers12061687] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 06/19/2020] [Accepted: 06/22/2020] [Indexed: 12/13/2022] Open
Abstract
Telomerase reverse transcriptase (TERT) is a conserved self-tumor antigen which is overexpressed in most tumors and plays a critical role in tumor formation and progression. As such, TERT is an antigen of great relevance to develop widely applicable immunotherapies. CD4 T cells play a major role in the anti-cancer response alone or with other effector cells such as CD8 T cells and NK cells. To date, efforts have been made to identify TERT peptides capable of stimulating CD4 T cells that are also able to bind diverse MHC-II alleles to ease immune status monitoring and immunotherapies. Here, we review the current status of TERT biology, TERT/MHC-II immunobiology, and past and current vaccine clinical trials. We propose that monitoring CD4 T cell immunity against TERT is a simple and direct way to assess immune surveillance in cancer patients and a new way to predict the response to immune checkpoint inhibitors (ICPi). Finally, we present the initial results of a systematic discovery of TERT peptides able to bind the most common HLA Class II alleles worldwide and show that the repertoire of MHC-II TERT peptides is wider than currently appreciated.
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Affiliation(s)
- Magalie Dosset
- The Laboratory of Immunology, Department of Medicine and Moores Cancer Center, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-081, USA;
| | - Andrea Castro
- Division of Medical Genetics, Department of Medicine and Bioinformatics and Systems Biology Program, University of California San Diego, La Jolla, CA 92093, USA; (A.C.); (H.C.)
- Health Science, Department of Biomedical Informatics, School of Medicine, University of California San Diego, La Jolla, CA 92093, USA
| | - Hannah Carter
- Division of Medical Genetics, Department of Medicine and Bioinformatics and Systems Biology Program, University of California San Diego, La Jolla, CA 92093, USA; (A.C.); (H.C.)
| | - Maurizio Zanetti
- The Laboratory of Immunology, Department of Medicine and Moores Cancer Center, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-081, USA;
- Correspondence:
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22
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Slusher AL, Kim JJJ, Ludlow AT. The Role of Alternative RNA Splicing in the Regulation of hTERT, Telomerase, and Telomeres: Implications for Cancer Therapeutics. Cancers (Basel) 2020; 12:E1514. [PMID: 32531916 PMCID: PMC7352778 DOI: 10.3390/cancers12061514] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 06/01/2020] [Accepted: 06/08/2020] [Indexed: 12/13/2022] Open
Abstract
Alternative RNA splicing impacts the majority (>90%) of eukaryotic multi-exon genes, expanding the coding capacity and regulating the abundance of gene isoforms. Telomerase (hTERT) is a key example of a gene that is alternatively spliced during human fetal development and becomes dysregulated in nearly all cancers. Approximately 90% of human tumors use telomerase to synthesize de novo telomere repeats and obtain telomere-dependent cellular immortality. Paradigm shifting data indicates that hTERT alternative splicing, in addition to transcription, plays an important role in the regulation of active telomerase in cells. Our group and others are pursuing the basic science studies to progress this emerging area of telomerase biology. Recent evidence demonstrates that switching splicing of hTERT from the telomerase activity producing full-length hTERT isoform to alternatively spliced, non-coding isoforms may be a novel telomerase inhibition strategy to prevent cancer growth and survival. Thus, the goals of this review are to detail the general roles of telomerase in cancer development, explore the emerging regulatory mechanisms of alternative RNA splicing of the hTERT gene in various somatic and cancer cell types, define the known and potential roles of hTERT splice isoforms in cancer cell biology, and provide insight into new treatment strategies targeting hTERT in telomerase-positive cancers.
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Affiliation(s)
| | | | - Andrew T. Ludlow
- School of Kinesiology, University of Michigan, Ann Arbor, MI 48109, USA; (A.L.S.); (J.J.K.)
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Thompson CA, Wong JM. Non-canonical Functions of Telomerase Reverse Transcriptase: Emerging Roles and Biological Relevance. Curr Top Med Chem 2020; 20:498-507. [DOI: 10.2174/1568026620666200131125110] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 01/10/2020] [Accepted: 01/21/2020] [Indexed: 12/11/2022]
Abstract
Increasing evidence from research on telomerase suggests that in addition to its catalytic telomere
repeat synthesis activity, telomerase may have other biologically important functions. The canonical
roles of telomerase are at the telomere ends where they elongate telomeres and maintain genomic
stability and cellular lifespan. The catalytic protein component Telomerase Reverse Transcriptase
(TERT) is preferentially expressed at high levels in cancer cells despite the existence of an alternative
mechanism for telomere maintenance (alternative lengthening of telomeres or ALT). TERT is also expressed
at higher levels than necessary for maintaining functional telomere length, suggesting other possible
adaptive functions. Emerging non-canonical roles of TERT include regulation of non-telomeric
DNA damage responses, promotion of cell growth and proliferation, acceleration of cell cycle kinetics,
and control of mitochondrial integrity following oxidative stress. Non-canonical activities of TERT primarily
show cellular protective effects, and nuclear TERT has been shown to protect against cell death
following double-stranded DNA damage, independent of its role in telomere length maintenance. TERT
has been suggested to act as a chromatin modulator and participate in the transcriptional regulation of
gene expression. TERT has also been reported to regulate transcript levels through an RNA-dependent
RNA Polymerase (RdRP) activity and produce siRNAs in a Dicer-dependent manner. At the mitochondria,
TERT is suggested to protect against oxidative stress-induced mtDNA damage and promote mitochondrial
integrity. These extra-telomeric functions of TERT may be advantageous in the context of increased
proliferation and metabolic stress often found in rapidly-dividing cancer cells. Understanding
the spectrum of non-canonical functions of telomerase may have important implications for the rational
design of anti-cancer chemotherapeutic drugs.
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Affiliation(s)
- Connor A.H. Thompson
- Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, V6T 1Z3, Canada
| | - Judy M.Y. Wong
- Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, V6T 1Z3, Canada
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24
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Nemirovich-Danchenko NM, Khodanovich MY. Telomerase Gene Editing in the Neural Stem Cells in vivo as a Possible New Approach against Brain Aging. RUSS J GENET+ 2020. [DOI: 10.1134/s1022795420040092] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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25
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Zhang Q, Liu N, Bai J, Zhou Q, Mao J, Xu L, Liu J, Wei H, Ren C, Wu X, Wang M, Zhao B, Cong YS. Human telomerase reverse transcriptase is a novel target of Hippo-YAP pathway. FASEB J 2020; 34:4178-4188. [PMID: 31950551 DOI: 10.1096/fj.201902147r] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 12/20/2019] [Accepted: 01/05/2020] [Indexed: 12/17/2022]
Abstract
Telomerase plays a pivotal role in tumorigenesis by maintaining telomere homeostasis, a hallmark of cancer. However, the mechanisms by which telomerase is reactivated or upregulated during tumorigenesis remain incompletely understood. Here, we report that the Hippo pathway effector Yes-associated protein (YAP) regulates the expression of human telomerase reverse transcriptase (hTERT). Ectopic expression or physiological activation of YAP increases hTERT expression, whereas knockdown of YAP decreases the expression of hTERT. YAP binds to the hTERT promoter through interaction with the TEA domain family transcription factors and activates hTERT transcription. Furthermore, sustained YAP hyperactivation promotes telomerase activity and extends telomere length, with increased hTERT expression. In addition, we show that hTERT expression is positively correlated with YAP activation in human liver cancer tissues. Together, our results demonstrate that YAP promotes hTERT expression, which could contribute to tumor progression.
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Affiliation(s)
- Qian Zhang
- Key Laboratory of Aging and Cancer Biology of Zhejiang Province, Institute of Aging Research, Hangzhou Normal University School of Medicine, Hangzhou, China
| | - Ning Liu
- College of Food Sciences & Technology, Shanghai Ocean University, Shanghai, China
| | - Junjie Bai
- Key Laboratory of Aging and Cancer Biology of Zhejiang Province, Institute of Aging Research, Hangzhou Normal University School of Medicine, Hangzhou, China
| | - Qi Zhou
- MOE Key Laboratory of Biosystems Homeostasis and Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou, China
| | - Jian Mao
- Key Laboratory of Aging and Cancer Biology of Zhejiang Province, Institute of Aging Research, Hangzhou Normal University School of Medicine, Hangzhou, China
| | - Lu Xu
- Key Laboratory of Aging and Cancer Biology of Zhejiang Province, Institute of Aging Research, Hangzhou Normal University School of Medicine, Hangzhou, China
| | - Jiang Liu
- Key Laboratory of Aging and Cancer Biology of Zhejiang Province, Institute of Aging Research, Hangzhou Normal University School of Medicine, Hangzhou, China
| | - Haibin Wei
- Zhejiang Cancer Research Institute, Zhejiang Cancer Hospital, Hangzhou, China
| | - Chengcheng Ren
- Key Laboratory of Aging and Cancer Biology of Zhejiang Province, Institute of Aging Research, Hangzhou Normal University School of Medicine, Hangzhou, China
| | - Xiaoying Wu
- Key Laboratory of Aging and Cancer Biology of Zhejiang Province, Institute of Aging Research, Hangzhou Normal University School of Medicine, Hangzhou, China
| | - Miao Wang
- Key Laboratory of Aging and Cancer Biology of Zhejiang Province, Institute of Aging Research, Hangzhou Normal University School of Medicine, Hangzhou, China
| | - Bin Zhao
- MOE Key Laboratory of Biosystems Homeostasis and Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou, China
| | - Yu-Sheng Cong
- Key Laboratory of Aging and Cancer Biology of Zhejiang Province, Institute of Aging Research, Hangzhou Normal University School of Medicine, Hangzhou, China
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26
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McKelvey BA, Umbricht CB, Zeiger MA. Telomerase Reverse Transcriptase (TERT) Regulation in Thyroid Cancer: A Review. Front Endocrinol (Lausanne) 2020; 11:485. [PMID: 32849278 PMCID: PMC7412884 DOI: 10.3389/fendo.2020.00485] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 06/22/2020] [Indexed: 12/17/2022] Open
Abstract
Telomerase reverse transcriptase (TERT) is the catalytic subunit of the enzyme telomerase and is essential for telomerase activity. Upregulation of TERT expression and resulting telomerase activity occurs in the large majority of malignancies, including thyroid cancer. This upregulation results in continued cellular proliferation and avoidance of cellular senescence and cell death. In this review we will briefly introduce TERT and telomerase activity as it pertains to thyroid cancer and, highlight the effects of TERT on cancer cells. We will also explore in detail the different TERT regulatory strategies and how TERT is reactivated in thyroid cancer cells, specifically. These regulatory mechanisms include both activating single base pair TERT promoter mutations and epigenetic changes at the promoter, including changes in CpG methylation and histone modifications that affect chromatin structure. Further, regulation includes the allele-specific regulation of the TERT promoter in thyroid cancer cells harboring the TERT promoter mutation. These entail allele-specific transcriptional activator binding, DNA methylation, histone modifications, and mono-allelic expression of TERT. Lastly, TERT copy number alterations and alternative splicing are also implicated. Both amplifications of the TERT locus and increased full-length transcripts and decreased inactive and dominant negative isoforms result in active telomerase. Finally, the clinical significance of TERT in thyroid cancer is also reviewed.
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Affiliation(s)
- Brittany A. McKelvey
- Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, United States
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Christopher B. Umbricht
- Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, United States
- Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Martha A. Zeiger
- Surgical Oncology Program, National Cancer Institute, National Institutes of Health, Bethesda, MD, United States
- *Correspondence: Martha A. Zeiger
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Ségal-Bendirdjian E, Geli V. Non-canonical Roles of Telomerase: Unraveling the Imbroglio. Front Cell Dev Biol 2019; 7:332. [PMID: 31911897 PMCID: PMC6914764 DOI: 10.3389/fcell.2019.00332] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 11/27/2019] [Indexed: 12/11/2022] Open
Abstract
Telomerase plays a critical role in stem cell function and tissue regeneration that depends on its ability to elongate telomeres. For nearly two decades, it turned out that TERT regulates a broad spectrum of functions including signal transduction, gene expression regulation, and protection against oxidative damage that are independent of its telomere elongation activity. These conclusions that were mainly obtained in cell lines overexpressing telomerase were further strengthened by in vivo models of ectopic expression of telomerase or models of G1 TERT knockout mice without detectable telomere dysfunction. However, the later models were questioned due to the presence of aberrantly shortened telomere in the germline of the parents TERT+/- that were used to create the G1 TERT -/- mice. The physiological relevance of the functions associated with overexpressed telomerase raised also some concerns due to artifactual situations and localizations and complications to quantify the level of TERT. Another concern with non-canonical functions of TERT was the difficulty to separate a direct TERT-related function from secondary effects. Despite these concerns, more and more evidence accumulates for non-canonical roles of telomerase that are non-obligatory extra-telomeric. Here, we review these non-canonical roles of the TERT subunit of telomerase. Also, we emphasize recent results that link TERT to mitochondria and protection to reactive oxygen species suggesting a protective role of TERT in neurons. Throughout this review, we dissect some controversies regarding the non-canonical functions of telomerase and provide some insights to explain these discrepancies. Finally, we discuss the importance of understanding these alternative functions of telomerase for the development of anticancer strategies.
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Affiliation(s)
- Evelyne Ségal-Bendirdjian
- INSERM UMR-S 1124, Team: Cellular Homeostasis, Cancer and Therapies, INSERM US36, CNRS UMS 2009, BioMedTech Facilities, Université de Paris, Paris, France
| | - Vincent Geli
- Marseille Cancer Research Center, U1068 INSERM, UMR 7258 CNRS, Aix Marseille University, Institut Paoli-Calmettes, Equipe labellisée Ligue, Marseille, France
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28
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Nersisyan L, Hopp L, Loeffler-Wirth H, Galle J, Loeffler M, Arakelyan A, Binder H. Telomere Length Maintenance and Its Transcriptional Regulation in Lynch Syndrome and Sporadic Colorectal Carcinoma. Front Oncol 2019; 9:1172. [PMID: 31750255 PMCID: PMC6848383 DOI: 10.3389/fonc.2019.01172] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2019] [Accepted: 10/18/2019] [Indexed: 12/14/2022] Open
Abstract
Background: Activation of telomere maintenance mechanisms (TMMs) is a hallmark of most cancers, and is required to prevent genome instability and to establish cellular immortality through reconstitution of capping of chromosome ends. TMM depends on the cancer type. Comparative studies linking tumor biology and TMM have potential impact for evaluating cancer onset and development. Methods: We have studied alterations of telomere length, their sequence composition and transcriptional regulation in mismatch repair deficient colorectal cancers arising in Lynch syndrome (LS-CRC) and microsatellite instable (MSI) sporadic CRC (MSI s-CRC), and for comparison, in microsatellite stable (MSS) s-CRC and in benign colon mucosa. Our study applied bioinformatics analysis of whole genome DNA and RNA sequencing data and a pathway model to study telomere length alterations and the potential effect of the "classical" telomerase (TEL-) and alternative (ALT-) TMM using transcriptomic signatures. Results: We have found progressive decrease of mean telomere length in all cancer subtypes compared with reference systems. Our results support the view that telomere attrition is an early event in tumorigenesis. TMM gets activated in all tumors studied due to concerted overexpression of a large fraction of genes with direct relation to telomere function, where only a very small fraction of them showed recurrent mutations. TEL-related transcriptional state was dominating in all CRC subtypes, showing, however, subtype-specific activation patterns; while contribution of the ALT-TMM was slightly more prominent in the hypermutated MSI s-CRC and LS-CRC. TEL-TMM is mainly activated by over-expression of DKC1 and/or TERT genes and their interaction partners, where DKC1 is more prominent in MSS than in MSI s-CRC and can serve as a transcriptomic marker of TMM activity. Conclusions: Our results suggest that transcriptional patterns are indicative for TMM pathway activation with subtle differences between TEL and ALT mechanisms in a CRC subtype-specific fashion. Sequencing data potentially provide a suited measure to study alterations of telomere length and of underlying transcriptional regulation. Further studies are needed to improve this method.
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Affiliation(s)
- Lilit Nersisyan
- Group of Bioinformatics, Institute of Molecular Biology, National Academy of Sciences, Yerevan, Armenia
| | - Lydia Hopp
- Interdisciplinary Centre for Bioinformatics, Leipzig University, Leipzig, Germany
| | - Henry Loeffler-Wirth
- Interdisciplinary Centre for Bioinformatics, Leipzig University, Leipzig, Germany
| | - Jörg Galle
- Interdisciplinary Centre for Bioinformatics, Leipzig University, Leipzig, Germany
| | - Markus Loeffler
- Interdisciplinary Centre for Bioinformatics, Leipzig University, Leipzig, Germany.,Institute for Medical Informatics, Statistics and Epidemiology, Leipzig University, Leipzig, Germany
| | - Arsen Arakelyan
- Group of Bioinformatics, Institute of Molecular Biology, National Academy of Sciences, Yerevan, Armenia
| | - Hans Binder
- Interdisciplinary Centre for Bioinformatics, Leipzig University, Leipzig, Germany
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Inflamm-Aging Is Associated with Lower Plasma PTX3 Concentrations and an Impaired Capacity of PBMCs to Express hTERT following LPS Stimulation. Mediators Inflamm 2019; 2019:2324193. [PMID: 31611733 PMCID: PMC6757284 DOI: 10.1155/2019/2324193] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Revised: 05/22/2019] [Accepted: 06/20/2019] [Indexed: 12/31/2022] Open
Abstract
Age-related elevations in proinflammatory cytokines, known as inflamm-aging, are associated with shorter immune cell telomere lengths. Purpose. This study examined the relationship of plasma PTX3 concentrations, a biomarker of appropriate immune function, with telomere length in 15 middle-aged (40-64 years) and 15 young adults (20-31 years). In addition, PBMCs were isolated from middle-aged and young adults to examine their capacity to express a key mechanistic component of telomere length maintenance, human telomerase reverse transcriptase (hTERT), following ex vivo cellular stimulation. Methods. Plasma PTX3 and inflammatory cytokines (i.e., IL-6, IL-10, TGF-β, and TNF-α), PBMC telomere lengths, and PBMC hTERT gene expression and inflammatory protein secretion following exposure to LPS, PTX3, and PTX3+LPS were measured. Results. Aging was accompanied by the accumulation of centrally located visceral adipose tissue, without changes in body weight and BMI, and alterations in the systemic inflammatory milieu (decreased plasma PTX3 and TGF-β; increased TNF-α (p ≤ 0.050)). In addition, shorter telomere lengths in middle-aged compared to young adults (p = 0.011) were negatively associated with age, body fat percentages, and plasma TNF-α (r = −0.404, p = 0.027; r = −0.427, p = 0.019; and r = −0.323, p = 0.041, respectively). Finally, the capacity of PBMCs to increase hTERT gene expression following ex vivo stimulation was impaired in middle-aged compared to young adults (p = 0.033) and negatively associated with telomere lengths (r = 0.353, p = 0.028). Conclusions. Proinflammation and the impaired hTERT gene expression capacity of PBMCs may contribute to age-related telomere attrition and disease.
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30
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Tanaka A, Matsuse M, Saenko V, Nakao T, Yamanouchi K, Sakimura C, Yano H, Nishihara E, Hirokawa M, Suzuki K, Miyauchi A, Eguchi S, Yoshiura KI, Yamashita S, Nagayasu T, Mitsutake N. TERT mRNA Expression as a Novel Prognostic Marker in Papillary Thyroid Carcinomas. Thyroid 2019; 29:1105-1114. [PMID: 31286848 DOI: 10.1089/thy.2018.0695] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Background: Telomerase reverse transcriptase (TERT) promoter mutations have been found in a subset of papillary thyroid carcinomas (PTCs) and are associated with tumor aggressiveness and worse prognosis. However, little is known about the status of TERT mRNA expression and its relationship between TERT promoter mutations and clinicopathological features. Methods: We analyzed 159 PTC samples for TERT promoter mutations using direct DNA sequencing. TERT expression was measured using quantitative reverse transcription polymerase chain reaction. To examine low allelic frequency of TERT promoter mutations with high sensitivity, we used droplet digital polymerase chain reaction (ddPCR). The relationship between the status of the TERT promoter mutation/expression and clinicopathological features including recurrence risk was statistically analyzed. Results:TERT promoter mutations were found in 20 cases (12.6%). However, TERT expression was observed not only in the mutation-positive tumors but also in 56 of 139 (40.3%) mutation-negative tumors. Among them, we detected low allelic frequency of TERT promoter mutations in three samples (5.4%) using ddPCR. We confirmed a significant association between TERT promoter mutations and aggressive clinicopathological features in this series. The risk of recurrence of TERT mutation-negative/expression-positive tumors was significantly higher than that of the mutation-negative/expression-negative tumors, suggesting that TERT expression even in absence of a mutation confers a negative influence on PTCs. Moreover, when we reclassified the mutation-negative cases into two groups based on the TERT expression levels: expression-negative/expression levels <80th percentile and expression levels >80th percentile because minimal expression may have a negligible clinical impact, a higher hazard ratio for recurrence was observed. Interestingly, TERT expression levels in the mutation-negative PTCs were inversely correlated with patient age and the presence of BRAF mutations. Conclusions: We confirm a strong correlation between the presence of TERT promoter mutations and aggressive clinicopathological features in this PTC series. In addition, there were PTCs showing high TERT mRNA expression even in the absence of TERT promoter mutations. These cases also showed a significantly higher recurrence rate. Since the TERT promoter mutations are observed only in elderly patients, TERT mRNA expression can be a useful prognostic marker especially in younger PTC patients.
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Affiliation(s)
- Aya Tanaka
- 1Department of Radiation Medical Sciences, Atomic Bomb Disease Institute, Nagasaki University, Nagasaki, Japan
- 2Department of Surgical Oncology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Michiko Matsuse
- 1Department of Radiation Medical Sciences, Atomic Bomb Disease Institute, Nagasaki University, Nagasaki, Japan
| | - Vladimir Saenko
- 3Department of Radiation Molecular Epidemiology, Atomic Bomb Disease Institute, Nagasaki University, Nagasaki, Japan
| | - Tomoe Nakao
- 1Department of Radiation Medical Sciences, Atomic Bomb Disease Institute, Nagasaki University, Nagasaki, Japan
- 4Department of Endocrinology and Metabolism, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Kosho Yamanouchi
- 5Department of Surgery, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Chika Sakimura
- 5Department of Surgery, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Hiroshi Yano
- 2Department of Surgical Oncology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Eijun Nishihara
- 6Department of Internal Medicine, Kuma Hospital, Kobe, Japan
| | - Mitsuyoshi Hirokawa
- 7Department of Diagnostic Pathology and Cytology, Kuma Hospital, Kobe, Japan
| | - Keiji Suzuki
- 1Department of Radiation Medical Sciences, Atomic Bomb Disease Institute, Nagasaki University, Nagasaki, Japan
| | | | - Susumu Eguchi
- 5Department of Surgery, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Ko-Ichiro Yoshiura
- 9Department of Human Genetics, Atomic Bomb Disease Institute, Nagasaki University, Nagasaki, Japan
| | - Shunichi Yamashita
- 1Department of Radiation Medical Sciences, Atomic Bomb Disease Institute, Nagasaki University, Nagasaki, Japan
| | - Takeshi Nagayasu
- 2Department of Surgical Oncology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Norisato Mitsutake
- 1Department of Radiation Medical Sciences, Atomic Bomb Disease Institute, Nagasaki University, Nagasaki, Japan
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Abstract
Many recent advances have emerged in the telomere and telomerase fields. This Timeline article highlights the key advances that have expanded our views on the mechanistic underpinnings of telomeres and telomerase and their roles in ageing and disease. Three decades ago, the classic view was that telomeres protected the natural ends of linear chromosomes and that telomerase was a specific telomere-terminal transferase necessary for the replication of chromosome ends in single-celled organisms. While this concept is still correct, many diverse fields associated with telomeres and telomerase have substantially matured. These areas include the discovery of most of the key molecular components of telomerase, implications for limits to cellular replication, identification and characterization of human genetic disorders that result in premature telomere shortening, the concept that inhibiting telomerase might be a successful therapeutic strategy and roles for telomeres in regulating gene expression. We discuss progress in these areas and conclude with challenges and unanswered questions in the field.
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Affiliation(s)
- Jerry W Shay
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX, USA.
| | - Woodring E Wright
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX, USA
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32
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Bartys N, Kierzek R, Lisowiec-Wachnicka J. The regulation properties of RNA secondary structure in alternative splicing. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2019; 1862:194401. [PMID: 31323437 DOI: 10.1016/j.bbagrm.2019.07.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 07/09/2019] [Indexed: 11/30/2022]
Abstract
The RNA secondary structure is important for many functional processes in the cell. The secondary and tertiary structures of cellular RNAs are essential for the activity of these molecules in processes such as transcription, splicing, translation, and localization. New high-throughput analytical methods, including next generation sequencing, have allowed for the in-depth characterization of the 'RNA structurome': a new term describing how the RNA structure controls the activity of RNA by itself and how it regulates the expression of genes. In this review, we present many examples of the influence of structural motifs of RNA, long range interactions and global RNA structure on the alternative splicing processes. This article is part of a Special Issue entitled: RNA structure and splicing regulation edited by Francisco Baralle, Ravindra Singh and Stefan Stamm.
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Affiliation(s)
- Natalia Bartys
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Z. Noskowskiego 12/14, 61-704 Poznań, Poland
| | - Ryszard Kierzek
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Z. Noskowskiego 12/14, 61-704 Poznań, Poland
| | - Jolanta Lisowiec-Wachnicka
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Z. Noskowskiego 12/14, 61-704 Poznań, Poland.
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Yuan X, Larsson C, Xu D. Mechanisms underlying the activation of TERT transcription and telomerase activity in human cancer: old actors and new players. Oncogene 2019; 38:6172-6183. [PMID: 31285550 PMCID: PMC6756069 DOI: 10.1038/s41388-019-0872-9] [Citation(s) in RCA: 250] [Impact Index Per Article: 50.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2019] [Revised: 06/20/2019] [Accepted: 06/20/2019] [Indexed: 12/25/2022]
Abstract
Long-lived species Homo sapiens have evolved robust protection mechanisms against cancer by repressing telomerase and maintaining short telomeres, thereby delaying the onset of the majority of cancer types until post-reproductive age. Indeed, telomerase is silent in most differentiated human cells, predominantly due to the transcriptional repression of its catalytic component telomerase reverse transcriptase (TERT) gene. The lack of telomerase/TERT expression leads to progressive telomere erosion in dividing human cells, whereas critically shortened telomere length induces a permanent growth arrest stage named replicative senescence. TERT/telomerase activation has been experimentally shown to be essential to cellular immortalization and malignant transformation by stabilizing telomere length and erasing the senescence barrier. Consistently, TERT expression/telomerase activity is detectable in up to 90% of human primary cancers. Compelling evidence has also accumulated that TERT contributes to cancer development and progression via multiple activities beyond its canonical telomere-lengthening function. Given these key roles of telomerase and TERT in oncogenesis, great efforts have been made to decipher mechanisms underlying telomerase activation and TERT induction. In the last two decades since the TERT gene and promoter were cloned, the derepression of the TERT gene has been shown to be achieved typically at a transcriptional level through dysregulation of oncogenic factors or signaling, post-transcriptional/translational regulation and genomic amplification. However, advances in high-throughput next-generation sequencing technologies have prompted a revolution in cancer genomics, which leads to the recent discovery that genomic alterations take center stage in activating the TERT gene. In this review article, we summarize critical mechanisms activating TERT transcription, with special emphases on the contribution of TERT promoter mutations and structural alterations at the TERT locus, and briefly discuss the underlying implications of these genomic events-driven TERT hyperactivity in cancer initiation/progression and potential clinical applications as well.
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Affiliation(s)
- Xiaotian Yuan
- School of Medicine, Shandong University, 250012, Jinan, People's Republic of China. .,Department of Medicine, Center for Molecular Medicine (CMM) and Bioclinicum, Karolinska Institutet and Karolinska University Hospital Solna, 171 64, Solna, Sweden.
| | - Catharina Larsson
- Department of Oncology-Pathology and Bioclinicum, Karolinska Institutet and Karolinska University Hospital Solna, 171 64, Solna, Sweden
| | - Dawei Xu
- Department of Medicine, Center for Molecular Medicine (CMM) and Bioclinicum, Karolinska Institutet and Karolinska University Hospital Solna, 171 64, Solna, Sweden.
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Mazzolini R, Gonzàlez N, Garcia-Garijo A, Millanes-Romero A, Peiró S, Smith S, García de Herreros A, Canudas S. Snail1 transcription factor controls telomere transcription and integrity. Nucleic Acids Res 2019; 46:146-158. [PMID: 29059385 PMCID: PMC5758914 DOI: 10.1093/nar/gkx958] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 10/16/2017] [Indexed: 02/06/2023] Open
Abstract
Besides controlling epithelial-to-mesenchymal transition (EMT) and cell invasion, the Snail1 transcriptional factor also provides cells with cancer stem cell features. Since telomere maintenance is essential for stemness, we have examined the control of telomere integrity by Snail1. Fluorescence in situ hybridization (FISH) analysis indicates that Snail1-depleted mouse mesenchymal stem cells (MSC) have both a dramatic increase of telomere alterations and shorter telomeres. Remarkably, Snail1-deficient MSC present higher levels of both telomerase activity and the long non-coding RNA called telomeric repeat-containing RNA (TERRA), an RNA that controls telomere integrity. Accordingly, Snail1 expression downregulates expression of the telomerase gene (TERT) as well as of TERRA 2q, 11q and 18q. TERRA and TERT are transiently downregulated during TGFβ-induced EMT in NMuMG cells, correlating with Snail1 expression. Global transcriptome analysis indicates that ectopic expression of TERRA affects the transcription of some genes induced during EMT, such as fibronectin, whereas that of TERT does not modify those genes. We propose that Snail1 repression of TERRA is required not only for telomere maintenance but also for the expression of a subset of mesenchymal genes.
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Affiliation(s)
- Rocco Mazzolini
- Programa de Recerca en Càncer, Institut Hospital del Mar d'Investigacions Mèdiques (IMIM), Barcelona, Spain
| | - Núria Gonzàlez
- Programa de Recerca en Càncer, Institut Hospital del Mar d'Investigacions Mèdiques (IMIM), Barcelona, Spain
| | - Andrea Garcia-Garijo
- Programa de Recerca en Càncer, Institut Hospital del Mar d'Investigacions Mèdiques (IMIM), Barcelona, Spain
| | - Alba Millanes-Romero
- Programa de Recerca en Càncer, Institut Hospital del Mar d'Investigacions Mèdiques (IMIM), Barcelona, Spain
| | - Sandra Peiró
- Programa de Recerca en Càncer, Institut Hospital del Mar d'Investigacions Mèdiques (IMIM), Barcelona, Spain
| | - Susan Smith
- Kimmel Center for Biology and Medicine at the Skirball Institute, Department of Pathology, New York University School of Medicine, New York University, USA
| | - Antonio García de Herreros
- Programa de Recerca en Càncer, Institut Hospital del Mar d'Investigacions Mèdiques (IMIM), Barcelona, Spain.,Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - Sílvia Canudas
- Programa de Recerca en Càncer, Institut Hospital del Mar d'Investigacions Mèdiques (IMIM), Barcelona, Spain.,Unitat de Nutrició Humana, Facultat de Medicina i Ciències de la Salut, Institut d'Investigació Sanitaria Pere Virgili (IISPV), Reus, Spain.,CIBER Fisiología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III (ISCIII), Madrid, Spain
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35
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Luo Z, Wang W, Li F, Songyang Z, Feng X, Xin C, Dai Z, Xiong Y. Pan-cancer analysis identifies telomerase-associated signatures and cancer subtypes. Mol Cancer 2019; 18:106. [PMID: 31179925 PMCID: PMC6556968 DOI: 10.1186/s12943-019-1035-x] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 05/29/2019] [Indexed: 01/09/2023] Open
Abstract
Background Cancer cells become immortalized through telomere maintenance mechanisms, such as telomerase reverse transcriptase (TERT) activation. In addition to maintaining telomere length, TERT activates manifold cell survival signaling pathways. However, telomerase-associated gene signatures in cancer remain elusive. Methods We performed a systematic analysis of TERT high (TERThigh) and low (TERTlow) cancers using multidimensional data from The Cancer Genome Atlas (TCGA). Multidimensional data were analyzed by propensity score matching weight algorithm. Coexpression networks were constructed by weight gene coexpression network analysis (WGCNA). Random forest classifiers were generated to identify cancer subtypes. Results The TERThigh-specific mRNA expression signature is associated with cell cycle-related coexpression modules across cancer types. Experimental screening of hub genes in the cell cycle module suggested TPX2 and EXO1 as potential regulators of telomerase activity and cell survival. MiRNA analysis revealed that the TERThigh-specific miR-17-92 cluster can target biological processes enriched in TERTlow cancer and that its expression is negatively correlated with the tumor/normal telomere length ratio. Intriguingly, TERThigh cancers tend to have mutations in extracellular matrix organization genes and amplify MAPK signaling. By mining the clinical actionable gene database, we uncovered a number of TERThigh-specific somatic mutations, amplifications and high expression genes containing therapeutic targets. Finally, a random forest classifier integrating telomerase-associated multi-omics signatures identifies two cancer subtypes showed profound differences in telomerase activity and patient survival. Conclusions In summary, our results depict a telomerase-associated molecular landscape in cancers and provide therapeutic opportunities for cancer treatment. Electronic supplementary material The online version of this article (10.1186/s12943-019-1035-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Zhenhua Luo
- Key Laboratory of Gene Engineering of the Ministry of Education and State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510006, China.,Division of Gastroenterology, Hepatology and Nutrition, Cincinnati Children's Hospital Medical Center and the Department of Pediatrics Cincinnati, Ohio, 45229, USA
| | - Weixu Wang
- College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China
| | - Feng Li
- Key Laboratory of Gene Engineering of the Ministry of Education and State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510006, China
| | - Zhou Songyang
- Key Laboratory of Gene Engineering of the Ministry of Education and State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510006, China.,Verna and Marrs Mclean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030, USA
| | - Xuyang Feng
- Department of Cancer Biology, University of Cincinnati, Cincinnati, OH, 45230, USA.,The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510275, China
| | - Changchang Xin
- Key Laboratory of Gene Engineering of the Ministry of Education and State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510006, China
| | - Zhiming Dai
- School of Data and Computer Science, Sun Yat-Sen University, Guangzhou, 510006, China.
| | - Yuanyan Xiong
- Key Laboratory of Gene Engineering of the Ministry of Education and State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510006, China.
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Insights into Telomerase/hTERT Alternative Splicing Regulation Using Bioinformatics and Network Analysis in Cancer. Cancers (Basel) 2019; 11:cancers11050666. [PMID: 31091669 PMCID: PMC6562651 DOI: 10.3390/cancers11050666] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2019] [Revised: 05/10/2019] [Accepted: 05/13/2019] [Indexed: 01/08/2023] Open
Abstract
The reactivation of telomerase in cancer cells remains incompletely understood. The catalytic component of telomerase, hTERT, is thought to be the limiting component in cancer cells for the formation of active enzymes. hTERT gene expression is regulated at several levels including chromatin, DNA methylation, transcription factors, and RNA processing events. Of these regulatory events, RNA processing has received little attention until recently. RNA processing and alternative splicing regulation have been explored to understand how hTERT is regulated in cancer cells. The cis- and trans-acting factors that regulate the alternative splicing choice of hTERT in the reverse transcriptase domain have been investigated. Further, it was discovered that the splicing factors that promote the production of full-length hTERT were also involved in cancer cell growth and survival. The goals are to review telomerase regulation via alternative splicing and the function of hTERT splicing variants and to point out how bioinformatics approaches are leading the way in elucidating the networks that regulate hTERT splicing choice and ultimately cancer growth.
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Okamoto K, Seimiya H. Revisiting Telomere Shortening in Cancer. Cells 2019; 8:cells8020107. [PMID: 30709063 PMCID: PMC6406355 DOI: 10.3390/cells8020107] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Revised: 01/28/2019] [Accepted: 01/28/2019] [Indexed: 12/21/2022] Open
Abstract
Telomeres, the protective structures of chromosome ends are gradually shortened by each cell division, eventually leading to senescence or apoptosis. Cancer cells maintain the telomere length for unlimited growth by telomerase reactivation or a recombination-based mechanism. Recent genome-wide analyses have unveiled genetic and epigenetic alterations of the telomere maintenance machinery in cancer. While telomerase inhibition reveals that longer telomeres are more advantageous for cell survival, cancer cells often have paradoxically shorter telomeres compared with those found in the normal tissues. In this review, we summarize the latest knowledge about telomere length alterations in cancer and revisit its rationality. Finally, we discuss the potential utility of telomere length as a prognostic biomarker.
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Affiliation(s)
- Keiji Okamoto
- Division of Molecular Biotherapy, Cancer Chemotherapy Center, Japanese Foundation for Cancer Research, Koto-ku, Tokyo 135-8550, Japan.
| | - Hiroyuki Seimiya
- Division of Molecular Biotherapy, Cancer Chemotherapy Center, Japanese Foundation for Cancer Research, Koto-ku, Tokyo 135-8550, Japan.
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NOVA1 directs PTBP1 to hTERT pre-mRNA and promotes telomerase activity in cancer cells. Oncogene 2018; 38:2937-2952. [PMID: 30568224 PMCID: PMC6474811 DOI: 10.1038/s41388-018-0639-8] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 10/24/2018] [Accepted: 12/04/2018] [Indexed: 11/09/2022]
Abstract
Alternative splicing is dysregulated in cancer cells, driving the production of isoforms that allow tumor cells to survive and continuously proliferate. Part of the reactivation of telomerase involves the splicing of hTERT transcripts to produce full-length (FL) TERT. Very few splicing factors to date have been described to interact with hTERT and promote the production of FL TERT. We recently described one such splicing factor, NOVA1, that acts as an enhancer of FL hTERT splicing, increases telomerase activity, and promotes telomere maintenance in cancer cells. NOVA1 is expressed primarily in neurons and is involved in neurogenesis. In the present studies, we describe that polypyrimidine-tract binding proteins (PTBPs), which are also typically involved in neurogenesis, are also participating in the splicing of hTERT to FL in cancer. Knockdown experiments of PTBP1 in cancer cells indicate that PTBP1 reduces hTERT FL splicing and telomerase activity. Stable knockdown of PTBP1 results in progressively shortened telomere length in H1299 and H920 lung cancer cells. RNA pulldown experiments reveal that PTBP1 interacts with hTERT pre-mRNA in a NOVA1 dependent fashion. Knockdown of PTBP1 increases the expression of PTBP2 which also interacts with NOVA1, potentially preventing the association of NOVA1 with hTERT pre-mRNA. These new data highlight that splicing in cancer cells is regulated by competition for splice sites and that combinations of splicing factors interact at cis regulatory sites on pre-mRNA transcripts. By employing hTERT as a model gene, we show the coordination of the splicing factors NOVA1 and PTBP1 in cancer by regulating telomerase that is expressed in the vast majority of cancer cell types.
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39
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Kazemi Noureini S, Fatemi L, Wink M. Telomere shortening in breast cancer cells (MCF7) under treatment with low doses of the benzylisoquinoline alkaloid chelidonine. PLoS One 2018; 13:e0204901. [PMID: 30281650 PMCID: PMC6169906 DOI: 10.1371/journal.pone.0204901] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 09/17/2018] [Indexed: 01/23/2023] Open
Abstract
Telomeres, the specialized dynamic structures at chromosome ends, regularly shrink with every replication. Thus, they function as an internal molecular clock counting down the number of cell divisions. However, most cancer cells escape this limitation by activating telomerase, which can maintain telomere length. Previous studies showed that the benzylisoquinoline alkaloid chelidonine stimulates multiple modes of cell death and strongly down-regulates telomerase. It is still unknown if down-regulation of telomerase by chelidonine boosts substantial telomere shortening. The breast cancer cell line MCF7 was sequentially treated with very low concentrations of chelidonine over several cell passages. Telomere length and telomerase activity were measured by a monochrome multiplex quantitative PCR and a q-TRAP assay, respectively. Changes in population size and doubling time correlated well with telomerase inhibition and telomere shortening. MCF7 cell growth was arrested completely after three sequential treatments with 0.1 μM chelidonine, each ending after 48 h, while telomere length was reduced to almost 10% of the untreated control. However, treatment with 0.01 μM chelidonine did not have any apparent consequence. In addition to dose and time dependent telomerase inhibition, chelidonine changed the splicing pattern of hTERT towards non-enzyme coding isoforms of the transcript. In conclusion, telomere length and telomere stability are strongly affected by chelidonine in addition to microtubule formation.
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Affiliation(s)
- Sakineh Kazemi Noureini
- Department of Biology, Faculty of Basic Sciences, Hakim Sabzevari University, Sabzevar, Iran
- * E-mail:
| | - Leili Fatemi
- Department of Biology, Faculty of Basic Sciences, Hakim Sabzevari University, Sabzevar, Iran
| | - Michael Wink
- Department of Biology, Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Heidelberg, Germany
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40
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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: 56] [Impact Index Per Article: 9.3] [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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Contact-independent suppressive activity of regulatory T cells is associated with telomerase inhibition, telomere shortening and target lymphocyte apoptosis. Mol Immunol 2018; 101:229-244. [PMID: 30025223 DOI: 10.1016/j.molimm.2018.07.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 07/02/2018] [Accepted: 07/11/2018] [Indexed: 02/08/2023]
Abstract
Regulatory T cells (Tregs) play a fundamental role in the maintenance of immunological tolerance by suppressing effector target T, B and NK lymphocytes. Contact-dependent suppression mechanisms have been well-studied, though contact-independent Treg activity is not fully understood. In the present study, we showed that human native Tregs, as well as induced ex vivo Tregs, can cause in vitro telomere-dependent senescence in target T, B and NK cells in a contact-independent manner. The co-cultivation of target cells with Tregs separated through porous membranes induced alternative splicing of the telomerase catalytic subunit hTERT (human Telomerase Reverse Transcriptase), which suppressed telomerase activity. Induction of the hTERT splicing variant was associated with increased expression of the apoptotic endonuclease EndoG, a splicing regulator. Inhibited telomerase in target cells co-cultivated with Tregs for a long period of time led to a decrease in their telomere lengths, cell cycle arrest, conversion of the target cells to replicative senescence and apoptotic death. Induced Tregs showed the ability to up-regulate EndoG expression, TERT alternative splicing and telomerase inhibition in mouse T, B and NK cells after in vivo administration. The results of the present study describe a novel mechanism of contact-independent Treg cell suppression that induces telomerase inhibition through the EndoG-provoked alternative splicing of hTERT and converts cells to senescence and apoptosis phenotypes.
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42
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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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43
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Li G, Shen J, Cao J, Zhou G, Lei T, Sun Y, Gao H, Ding Y, Xu W, Zhan Z, Chen Y, Huang H. Alternative splicing of human telomerase reverse transcriptase in gliomas and its modulation mediated by CX-5461. JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2018; 37:78. [PMID: 29631594 PMCID: PMC5891986 DOI: 10.1186/s13046-018-0749-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Accepted: 04/02/2018] [Indexed: 02/08/2023]
Abstract
Background Glioma is a heterogeneous, invasive primary brain tumor with a wide range of patient survival and a lack of reliable prognostic biomarkers. Human telomerase reverse transcriptase (hTERT) has been reported in the presence of multiple transcripts in various tumor systems. The biological function and precise regulatory mechanisms of hTERT transcripts remain uncertain. Methods Alternative splicing of hTERT and telomerase activity were examined in 96 glioma specimens, including 38 glioblastomas (GBMs), 23 oligodendrogliomas (ODMs), and 35 oligoastrocytomas (OAMs). The correlation between telomerase activity or hTERT transcripts and patient clinical characteristics was investigated. We examined the regulation of alternative splicing of hTERT and telomerase activity by G-quadruplex stabilizer CX-5461 in GBM cells. The biological effects of CX-5461 on GBM cell lines, including inhibition of cell proliferation, effects on cell cycle/apoptosis, and telomere DNA damage were further explored. Results The β splicing was verified in human gliomas and hTERT+β was significantly correlated with higher telomerase activity, higher KPS, larger tumor size, and higher tumor grades. Meanwhile, glioma patients lacking hTERT+β expression or telomerase activity showed a significant survival benefit. Notably, CX-5461 altered hTERT splicing patterns, leading to an increase of hTERT-β transcript and a decrease of hTERT+β transcript expression, which inhibits telomerase activity. In addition, CX-5461 had cytotoxic effects on GBM cells and caused telomere DNA damage response, induced G2/M arrest and apoptosis. Conclusions The hTERT+β is verified to be correlated with clinical parameters in gliomas, and could serve as a prognostic marker or possibly therapeutic target for gliomas. CX-5461 can regulate the splicing pattern of hTERT, inhibit telomerase activity, and kill GBM cells.
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Affiliation(s)
- Guihong Li
- Department of Neurosurgery, First Hospital of Jilin University, Changchun, 130021, China.,Department of Neurosurgery, First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450000, China
| | - Jing Shen
- Department of Cardiology, Shengze Hospital of Jiangsu Province, Suzhou, 215200, China
| | - Junguo Cao
- Department of Neurosurgery, First Hospital of Jilin University, Changchun, 130021, China
| | - Guangtong Zhou
- Department of Neurosurgery, First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450000, China
| | - Ting Lei
- Department of Neurovascular Research Laboratory and Neuroscience, Universitat Autonoma de Barcelona, 08035, Barcelona, Spain
| | - Yuxue Sun
- Department of Neurosurgery, First Hospital of Jilin University, Changchun, 130021, China
| | - Haijun Gao
- Department of Neurosurgery, First Hospital of Jilin University, Changchun, 130021, China
| | - Yaonan Ding
- Department of Neurosurgery, First Hospital of Jilin University, Changchun, 130021, China
| | - Weidong Xu
- Department of Neurosurgery, First Hospital of Jilin University, Changchun, 130021, China
| | - Zhixin Zhan
- Department of Neurosurgery, First Hospital of Jilin University, Changchun, 130021, China
| | - Yong Chen
- Department of Neurosurgery, First Hospital of Jilin University, Changchun, 130021, China.
| | - Haiyan Huang
- Department of Neurosurgery, First Hospital of Jilin University, Changchun, 130021, China.
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Maguire D, Neytchev O, Talwar D, McMillan D, Shiels PG. Telomere Homeostasis: Interplay with Magnesium. Int J Mol Sci 2018; 19:E157. [PMID: 29303978 PMCID: PMC5796106 DOI: 10.3390/ijms19010157] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Revised: 12/21/2017] [Accepted: 01/03/2018] [Indexed: 12/14/2022] Open
Abstract
Telomere biology, a key component of the hallmarks of ageing, offers insight into dysregulation of normative ageing processes that accompany age-related diseases such as cancer. Telomere homeostasis is tightly linked to cellular metabolism, and in particular with mitochondrial physiology, which is also diminished during cellular senescence and normative physiological ageing. Inherent in the biochemistry of these processes is the role of magnesium, one of the main cellular ions and an essential cofactor in all reactions that use ATP. Magnesium plays an important role in many of the processes involved in regulating telomere structure, integrity and function. This review explores the mechanisms that maintain telomere structure and function, their influence on circadian rhythms and their impact on health and age-related disease. The pervasive role of magnesium in telomere homeostasis is also highlighted.
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Affiliation(s)
- Donogh Maguire
- Emergency Medicine Department, Glasgow Royal Infirmary, Glasgow G4 0SF, UK.
- Academic Unit of Surgery, School of Medicine, University of Glasgow, Glasgow Royal Infirmary, Glasgow G4 0SF, UK.
| | - Ognian Neytchev
- Section of Epigenetics, Institute of Cancer Sciences, University of Glasgow, Glasgow G61 1QH, UK.
| | - Dinesh Talwar
- The Scottish Trace Element and Micronutrient Reference Laboratory, Department of Biochemistry, Royal Infirmary, Glasgow G31 2ER, UK.
| | - Donald McMillan
- Academic Unit of Surgery, School of Medicine, University of Glasgow, Glasgow Royal Infirmary, Glasgow G4 0SF, UK.
| | - Paul G Shiels
- Section of Epigenetics, Institute of Cancer Sciences, University of Glasgow, Glasgow G61 1QH, UK.
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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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46
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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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Hugdahl E, Kalvenes MB, Mannelqvist M, Ladstein RG, Akslen LA. Prognostic impact and concordance of TERT promoter mutation and protein expression in matched primary and metastatic cutaneous melanoma. Br J Cancer 2017; 118:98-105. [PMID: 29123258 PMCID: PMC5765228 DOI: 10.1038/bjc.2017.384] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Revised: 09/13/2017] [Accepted: 10/02/2017] [Indexed: 01/05/2023] Open
Abstract
Background: TERT promoter mutations are frequent in melanoma. Here we analysed the concordance and prognostic impact of TERT mutation and telomerase reverse transcriptase (TERT) protein expression in a large melanoma series. Methods: In 194 primary nodular melanomas with 72 matched loco-regional metastases, TERT promoter mutation status was assessed by Sanger sequencing and TERT protein expression by immunohistochemistry. Results: TERT mutations were found in 68% of primary melanomas and 64% of metastases, and the mutation status was discordant between primary tumour and metastasis in 24% of the cases. 6 of the 10 cases with discordant and wild-type metastases were also TERT wild type when re-tested in other intra-tumour regions, whereas 4 cases were mutation positive. TERT-mutated tumours tended to be thicker, have a higher mitotic count and higher patient age than TERT wild-type cases, but there was no significant association with reduced survival. TERT protein expression did not correlate with mutation status, but showed a similar discordancy between the primary and first metastatic lesion, and was significantly associated with reduced survival. Conclusions: TERT promoter mutations showed inter- and intra-tumoural discordancy, whereas only expression of TERT protein was associated with reduced patient survival.
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Affiliation(s)
- Emilia Hugdahl
- Centre for Cancer Biomarkers CCBIO, Department of Clinical Medicine, University of Bergen, Bergen 5021, Norway
| | - May Britt Kalvenes
- Centre for Cancer Biomarkers CCBIO, Department of Clinical Medicine, University of Bergen, Bergen 5021, Norway
| | - Monica Mannelqvist
- Centre for Cancer Biomarkers CCBIO, Department of Clinical Medicine, University of Bergen, Bergen 5021, Norway
| | - Rita G Ladstein
- Centre for Cancer Biomarkers CCBIO, Department of Clinical Medicine, University of Bergen, Bergen 5021, Norway.,Department of Dermatology, Haukeland University Hospital, Bergen 5021, Norway
| | - Lars A Akslen
- Centre for Cancer Biomarkers CCBIO, Department of Clinical Medicine, University of Bergen, Bergen 5021, Norway.,Department of Pathology, Haukeland University Hospital, Bergen 5021, Norway
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48
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Structure and function of the alternatively spliced isoforms of the ecdysone receptor gene in the Chinese mitten crab, Eriocheir sinensis. Sci Rep 2017; 7:12993. [PMID: 29021633 PMCID: PMC5636884 DOI: 10.1038/s41598-017-13474-1] [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: 02/22/2017] [Accepted: 09/26/2017] [Indexed: 11/10/2022] Open
Abstract
Alternative splicing is an essential molecular mechanism that increase the protein diversity of a species to regulate important biological processes. Ecdysone receptor (EcR), an essential nuclear receptor, is essential in the molting, growth, development, reproduction, and regeneration of crustaceans. In this study, the whole sequence of EcR gene from Eriocheir sinensis was obtained. The sequence was 45,481 bp in length with 9 exons. Moreover, four alternatively spliced EcR isoforms (Es-EcR-1, Es-EcR-2, Es-EcR-3 and Es-EcR-4) were identified. The four isoforms harbored a common A/B domain and a DNA-binding region but different D domains and ligand-binding regions. Three alternative splicing patterns (alternative 5′ splice site, exon skipping, and intron retention) were identified in the four isoforms. Functional studies indicated that the four isoforms have specific functions. Es-EcR-3 may play essential roles in regulating periodic molting. Es-EcR-2 may participate in the regulation of ovarian development. Our results indicated that Es-EcR has broad regulatory functions in molting and development and established the molecular basis for the investigation of ecdysteroid signaling related pathways in E. sinensis.
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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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50
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KMT2A promotes melanoma cell growth by targeting hTERT signaling pathway. Cell Death Dis 2017; 8:e2940. [PMID: 28726783 PMCID: PMC5550845 DOI: 10.1038/cddis.2017.285] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 05/24/2017] [Accepted: 05/26/2017] [Indexed: 01/08/2023]
Abstract
Melanoma is an aggressive cutaneous malignancy, illuminating the exact mechanisms and finding novel therapeutic targets are urgently needed. In this study, we identified KMT2A as a potential target, which promoted the growth of human melanoma cells. KMT2A knockdown significantly inhibited cell viability and cell migration and induced apoptosis, whereas KMT2A overexpression effectively promoted cell proliferation in various melanoma cell lines. Further study showed that KMT2A regulated melanoma cell growth by targeting the hTERT-dependent signal pathway. Knockdown of KMT2A markedly inhibited the promoter activity and expression of hTERT, and hTERT overexpression rescued the viability inhibition caused by KMT2A knockdown. Moreover, KMT2A knockdown suppressed tumorsphere formation and the expression of cancer stem cell markers, which was also reversed by hTERT overexpression. In addition, the results from a xenograft mouse model confirmed that KMT2A promoted melanoma growth via hTERT signaling. Finally, analyses of clinical samples demonstrated that the expression of KMT2A and hTERT were positively correlated in melanoma tumor tissues, and KMT2A high expression predicted poor prognosis in melanoma patients. Collectively, our results indicate that KMT2A promotes melanoma growth by activating the hTERT signaling, suggesting that the KMT2A/hTERT signaling pathway may be a potential therapeutic target for melanoma.
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