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Dos Santos GA, Viana NI, Pimenta R, de Camargo JA, Guimaraes VR, Romão P, Candido P, Dos Santos VG, Ghazarian V, Reis ST, Leite KRM, Srougi M. Upregulation of shelterin and CST genes and longer telomeres are associated with unfavorable prognostic characteristics in prostate cancer. Cancer Genet 2024; 284-285:20-29. [PMID: 38503134 DOI: 10.1016/j.cancergen.2024.03.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 02/20/2024] [Accepted: 03/14/2024] [Indexed: 03/21/2024]
Abstract
INTRODUCTION Search for new clinical biomarkers targets in prostate cancer (PC) is urgent. Telomeres might be one of these targets. Telomeres are the extremities of linear chromosomes, essential for genome stability and control of cell divisions. Telomere homeostasis relies on the proper functioning of shelterin and CST complexes. Telomeric dysfunction and abnormal expression of its components are reported in most cancers and are associated with PC. Despite this, there are only a few studies about the expression of the main telomere complexes and their relationship with PC progression. We aimed to evaluate the role of shelterin (POT1, TRF2, TPP1, TIN2, and RAP1) and CST (CTC1, STN1, and TEN1) genes and telomere length in the progression of PC. METHODS We evaluated genetic alterations of shelterin and CST by bioinformatics in samples of localized (n = 499) and metastatic castration-resistant PC (n = 444). We also analyzed the expression of the genes using TCGA (localized PC n = 497 and control n = 152) and experimental approaches, with surgical specimens (localized PC n = 81 and BPH n = 10) and metastatic cell lines (LNCaP, DU145, PC3 and PNT2 as control) by real-time PCR. Real-time PCR also determined the telomere length in the same experimental samples. All acquired data were associated with clinical parameters. RESULTS Genetic alterations are uncommon in PC, but POT1, TIN2, and TEN1 showed significantly more amplifications in the metastatic cancer. Except for CTC1 and TEN1, which are differentially expressed in localized PC samples, we did not detect an expression pattern relative to control and cell lines. Nevertheless, except for TEN1, the upregulation of all genes is associated with a worse prognosis in localized PC. We also found that increased telomere length is associated with disease aggressiveness in localized PC. CONCLUSION The upregulation of shelterin and CST genes creates an environment that favors telomere elongation, giving selective advantages for localized PC cells to progress to more aggressive stages of the disease.
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Affiliation(s)
- Gabriel Arantes Dos Santos
- Laboratory of Medical Investigation (LIM55), Urology Department, Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, Brazil.
| | - Nayara I Viana
- Laboratory of Medical Investigation (LIM55), Urology Department, Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, Brazil; Minas Gerais State University (UEMG), Passos, Minas Gerais, Brazil
| | - Ruan Pimenta
- Laboratory of Medical Investigation (LIM55), Urology Department, Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, Brazil; D'Or Institute for Research and Education (IDOR), Sao Paulo, Brazil
| | - Juliana Alves de Camargo
- Laboratory of Medical Investigation (LIM55), Urology Department, Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, Brazil
| | - Vanessa R Guimaraes
- Laboratory of Medical Investigation (LIM55), Urology Department, Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, Brazil
| | - Poliana Romão
- Laboratory of Medical Investigation (LIM55), Urology Department, Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, Brazil
| | - Patrícia Candido
- Laboratory of Medical Investigation (LIM55), Urology Department, Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, Brazil
| | - Vinicius Genuino Dos Santos
- Laboratory of Medical Investigation (LIM55), Urology Department, Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, Brazil
| | - Vitória Ghazarian
- Laboratory of Medical Investigation (LIM55), Urology Department, Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, Brazil
| | - Sabrina T Reis
- Laboratory of Medical Investigation (LIM55), Urology Department, Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, Brazil; Minas Gerais State University (UEMG), Passos, Minas Gerais, Brazil
| | - Katia Ramos Moreira Leite
- Laboratory of Medical Investigation (LIM55), Urology Department, Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, Brazil
| | - Miguel Srougi
- Laboratory of Medical Investigation (LIM55), Urology Department, Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, Brazil; D'Or Institute for Research and Education (IDOR), Sao Paulo, Brazil
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Reddy V, Hwang C, Reddy GPV, Kim SH. A Novel Role of Prostate-Specific Membrane Antigen in Telomere Stability in Prostate Cancer Cells. Mol Cancer Res 2023; 21:1176-1185. [PMID: 37477641 DOI: 10.1158/1541-7786.mcr-23-0075] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 06/15/2023] [Accepted: 07/18/2023] [Indexed: 07/22/2023]
Abstract
Prostate-specific membrane antigen (PSMA) expression increases with prostate cancer grade and progression; however, the role of PSMA in prostate cancer progression remains poorly understood. Telomere stability is essential for the survival and genome stability of cancer cells. We found massive telomere DNA damage in PSMA-negative prostate cancer cells (PC-3 and DU145) compared with PSMA-positive prostate cancer (LNCaP) cells. The ectopic expression of PSMA suppressed telomere DNA damage in PC3 cells. PSMA inhibitor, 2-PMPA, and PSMA knockdown induced telomere DNA damage in PSMA-positive LNCaP cells but not in PSMA-negative PC-3 cells, suggesting that PSMA plays a critical role in telomere stability in prostate cancer cells. In addition, we observed that inhibition of PSMA or inhibition of glutamate receptor, which mediates PSMA-dependent activation of AKT, suppressed AKT phosphorylation, and caused telomere DNA damage. Furthermore, 2-PMPA-induced telomere DNA damage in LNCaP cells was associated with telomere aberrations, such as telomere-telomere fusions, sister-chromatid telomere fusions, and telomere breakages. AKT is reported to promote cell growth by stabilizing telomere association with telomere-binding proteins TRF1 and TPP1. We observed that TRF1 and TPP1 transfection of LNCaP cells attenuated the inhibitory effect of 2-PMPA on cell growth and telomere DNA damage. Together, these observations indicate that PSMA role in maintaining telomere stability in prostate cancer cells is mediated by AKT. Thus, these studies reveal an important role of PSMA in maintaining telomere stability that can promote cell survival and, thereby, prostate cancer progression. IMPLICATIONS Role of PSMA in telomere stability suggests a strong correlation between PSMA expression and prostate cancer progression.
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Affiliation(s)
- Vidyavathi Reddy
- Department of Urology, Vattikuti Urology Institute, Henry Ford Health, Detroit, Michigan
| | - Clara Hwang
- Department of Internal Medicine, Henry Ford Health, Detroit, Michigan
| | - G Prem-Veer Reddy
- Department of Urology, Vattikuti Urology Institute, Henry Ford Health, Detroit, Michigan
| | - Sahn-Ho Kim
- Department of Urology, Vattikuti Urology Institute, Henry Ford Health, Detroit, Michigan
- Department of Physiology, College of Human Medicine, Michigan State University, East Lansing, Michigan
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3
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Storchova R, Palek M, Palkova N, Veverka P, Brom T, Hofr C, Macurek L. Phosphorylation of TRF2 promotes its interaction with TIN2 and regulates DNA damage response at telomeres. Nucleic Acids Res 2023; 51:1154-1172. [PMID: 36651296 PMCID: PMC9943673 DOI: 10.1093/nar/gkac1269] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 11/25/2022] [Accepted: 12/23/2022] [Indexed: 01/19/2023] Open
Abstract
Protein phosphatase magnesium-dependent 1 delta (PPM1D) terminates the cell cycle checkpoint by dephosphorylating the tumour suppressor protein p53. By targeting additional substrates at chromatin, PPM1D contributes to the control of DNA damage response and DNA repair. Using proximity biotinylation followed by proteomic analysis, we identified a novel interaction between PPM1D and the shelterin complex that protects telomeric DNA. In addition, confocal microscopy revealed that endogenous PPM1D localises at telomeres. Further, we found that ATR phosphorylated TRF2 at S410 after induction of DNA double strand breaks at telomeres and this modification increased after inhibition or loss of PPM1D. TRF2 phosphorylation stimulated its interaction with TIN2 both in vitro and at telomeres. Conversely, induced expression of PPM1D impaired localisation of TIN2 and TPP1 at telomeres. Finally, recruitment of the DNA repair factor 53BP1 to the telomeric breaks was strongly reduced after inhibition of PPM1D and was rescued by the expression of TRF2-S410A mutant. Our results suggest that TRF2 phosphorylation promotes the association of TIN2 within the shelterin complex and regulates DNA repair at telomeres.
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Affiliation(s)
- Radka Storchova
- Cancer Cell Biology, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague CZ-14220, Czech Republic
| | - Matous Palek
- Cancer Cell Biology, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague CZ-14220, Czech Republic
| | - Natalie Palkova
- Cancer Cell Biology, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague CZ-14220, Czech Republic
| | - Pavel Veverka
- LifeB, Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno CZ-62500, Czech Republic
| | - Tomas Brom
- LifeB, Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno CZ-62500, Czech Republic
| | - Ctirad Hofr
- LifeB, Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno CZ-62500, Czech Republic
| | - Libor Macurek
- Cancer Cell Biology, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague CZ-14220, Czech Republic
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Gao X, Yu X, Zhang C, Wang Y, Sun Y, Sun H, Zhang H, Shi Y, He X. Telomeres and Mitochondrial Metabolism: Implications for Cellular Senescence and Age-related Diseases. Stem Cell Rev Rep 2022; 18:2315-2327. [PMID: 35460064 PMCID: PMC9033418 DOI: 10.1007/s12015-022-10370-8] [Citation(s) in RCA: 68] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/15/2022] [Indexed: 02/06/2023]
Abstract
Cellular senescence is an irreversible cell arrest process, which is determined by a variety of complicated mechanisms, including telomere attrition, mitochondrial dysfunction, metabolic disorders, loss of protein homeostasis, epigenetic changes, etc. Cellular senescence is causally related to the occurrence and development of age-related disease. The elderly is liable to suffer from disorders such as neurodegenerative diseases, cancer, and diabetes. Therefore, it is increasingly imperative to explore specific countermeasures for the treatment of age-related diseases. Numerous studies on humans and mice emphasize the significance of metabolic imbalance caused by short telomeres and mitochondrial damages in the onset of age-related diseases. Although the experimental data are relatively independent, more and more evidences have shown that there is mutual crosstalk between telomeres and mitochondrial metabolism in the process of cellular senescence. This review systematically discusses the relationship between telomere length, mitochondrial metabolic disorder, as well as their underlying mechanisms for cellular senescence and age-related diseases. Future studies on telomere and mitochondrial metabolism may shed light on potential therapeutic strategies for age-related diseases. Graphical Abstract The characteristics of cellular senescence mainly include mitochondrial dysfunction and telomere attrition. Mitochondrial dysfunction will cause mitochondrial metabolic disorders, including decreased ATP production, increased ROS production, as well as enhanced cellular apoptosis. While oxidative stress reaction to produce ROS, leads to DNA damage, and eventually influences telomere length. Under the stimulation of oxidative stress, telomerase catalytic subunit TERT mainly plays an inhibitory role on oxidative stress, reduces the production of ROS and protects telomere function. Concurrently, mitochondrial dysfunction and telomere attrition eventually induce a range of age-related diseases, such as T2DM, osteoporosis, AD, etc. :increase; :reduce;⟝:inhibition.
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Affiliation(s)
- Xingyu Gao
- The Key Laboratory of Pathobiology, Ministry of Education, College of Basic Medical Sciences, Jilin University, 126 Xinmin Street, Changchun, 130021, China
| | - Xiao Yu
- The Key Laboratory of Pathobiology, Ministry of Education, College of Basic Medical Sciences, Jilin University, 126 Xinmin Street, Changchun, 130021, China
| | - Chang Zhang
- The Key Laboratory of Pathobiology, Ministry of Education, College of Basic Medical Sciences, Jilin University, 126 Xinmin Street, Changchun, 130021, China
| | - Yiming Wang
- The Key Laboratory of Pathobiology, Ministry of Education, College of Basic Medical Sciences, Jilin University, 126 Xinmin Street, Changchun, 130021, China
| | - Yanan Sun
- The Key Laboratory of Pathobiology, Ministry of Education, College of Basic Medical Sciences, Jilin University, 126 Xinmin Street, Changchun, 130021, China
| | - Hui Sun
- The Key Laboratory of Pathobiology, Ministry of Education, College of Basic Medical Sciences, Jilin University, 126 Xinmin Street, Changchun, 130021, China
| | - Haiying Zhang
- The Key Laboratory of Pathobiology, Ministry of Education, College of Basic Medical Sciences, Jilin University, 126 Xinmin Street, Changchun, 130021, China
| | - Yingai Shi
- The Key Laboratory of Pathobiology, Ministry of Education, College of Basic Medical Sciences, Jilin University, 126 Xinmin Street, Changchun, 130021, China
| | - Xu He
- The Key Laboratory of Pathobiology, Ministry of Education, College of Basic Medical Sciences, Jilin University, 126 Xinmin Street, Changchun, 130021, China.
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Yin S, Zhang F, Lin S, Chen W, Weng K, Liu D, Wang C, He Z, Chen Y, Ma W, Huang J, Huang Y, Songyang Z. TIN2 deficiency leads to ALT-associated phenotypes and differentiation defects in embryonic stem cells. Stem Cell Reports 2022; 17:1183-1197. [PMID: 35395177 PMCID: PMC9120858 DOI: 10.1016/j.stemcr.2022.03.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 03/07/2022] [Accepted: 03/08/2022] [Indexed: 11/17/2022] Open
Abstract
Telomere integrity is critical for embryonic development, and core telomere-binding proteins, such as TIN2, are key to maintaining telomere stability. Here, we report that homozygous Tin2S341X resulted in embryonic lethality in mice and reduced expression of Tin2 in the derived mouse embryonic stem cells (mESCs). Homozygous mutant mESCs were able to self-renew and remain undifferentiated but displayed many phenotypes associated with alternative lengthening of telomeres (ALT), including excessively long and heterogeneous telomeres, increased ALT-associated promyelocytic leukemia (PML) bodies, and unstable chromosomal ends. These cells also showed upregulation of Zscan4 expression and elevated targeting of DAXX/ATRX and H3K9me3 marks on telomeres. Furthermore, the mutant mESCs were impeded in their differentiation capacity. Upon differentiation, DAXX/ATRX and PML bodies disassociated from telomeres in these cells, where elevated DNA damage was also apparent. Our results reveal differential responses to telomere dysfunction in mESCs versus differentiated cells and highlight the critical role of TIN2 in embryonic development.
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Affiliation(s)
- Shanshan Yin
- MOE Key Laboratory of Gene Function and Regulation, Guangzhou Key Laboratory of Healthy Aging Research, SYSU-BCM Joint Research Center, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China; Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China
| | - Fangyingnan Zhang
- MOE Key Laboratory of Gene Function and Regulation, Guangzhou Key Laboratory of Healthy Aging Research, SYSU-BCM Joint Research Center, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Song Lin
- MOE Key Laboratory of Gene Function and Regulation, Guangzhou Key Laboratory of Healthy Aging Research, SYSU-BCM Joint Research Center, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Wei Chen
- MOE Key Laboratory of Gene Function and Regulation, Guangzhou Key Laboratory of Healthy Aging Research, SYSU-BCM Joint Research Center, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Kai Weng
- Shanghai Institute of Precision Medicine, Shanghai 200125, China
| | - Dan Liu
- Verna and Marrs Mclean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Chuanle Wang
- MOE Key Laboratory of Gene Function and Regulation, Guangzhou Key Laboratory of Healthy Aging Research, SYSU-BCM Joint Research Center, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Zibin He
- MOE Key Laboratory of Gene Function and Regulation, Guangzhou Key Laboratory of Healthy Aging Research, SYSU-BCM Joint Research Center, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Yuxi Chen
- MOE Key Laboratory of Gene Function and Regulation, Guangzhou Key Laboratory of Healthy Aging Research, SYSU-BCM Joint Research Center, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Wenbin Ma
- MOE Key Laboratory of Gene Function and Regulation, Guangzhou Key Laboratory of Healthy Aging Research, SYSU-BCM Joint Research Center, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Junjiu Huang
- MOE Key Laboratory of Gene Function and Regulation, Guangzhou Key Laboratory of Healthy Aging Research, SYSU-BCM Joint Research Center, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Yan Huang
- MOE Key Laboratory of Gene Function and Regulation, Guangzhou Key Laboratory of Healthy Aging Research, SYSU-BCM Joint Research Center, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China.
| | - Zhou Songyang
- MOE Key Laboratory of Gene Function and Regulation, Guangzhou Key Laboratory of Healthy Aging Research, SYSU-BCM Joint Research Center, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China; Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China; Bioland Laboratory (Guangzhou Regenerative Medicine and Health Guangdong Laboratory), Guangzhou 510005, China.
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6
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Ghadaouia S, Olivier MA, Martinez A, Kientega T, Qin J, Lambert-Lanteigne P, Cardin GB, Autexier C, Malaquin N, Rodier F. Homologous recombination-mediated irreversible genome damage underlies telomere-induced senescence. Nucleic Acids Res 2021; 49:11690-11707. [PMID: 34725692 PMCID: PMC8599762 DOI: 10.1093/nar/gkab965] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 09/28/2021] [Accepted: 10/12/2021] [Indexed: 12/12/2022] Open
Abstract
Loss of telomeric DNA leads to telomere uncapping, which triggers a persistent, p53-centric DNA damage response that sustains a stable senescence-associated proliferation arrest. Here, we show that in normal cells telomere uncapping triggers a focal telomeric DNA damage response accompanied by a transient cell cycle arrest. Subsequent cell division with dysfunctional telomeres resulted in sporadic telomeric sister chromatid fusions that gave rise to next-mitosis genome instability, including non-telomeric DNA lesions responsible for a stable, p53-mediated, senescence-associated proliferation arrest. Unexpectedly, the blocking of Rad51/RPA-mediated homologous recombination, but not non-homologous end joining (NHEJ), prevented senescence despite multiple dysfunctional telomeres. When cells approached natural replicative senescence, interphase senescent cells displayed genome instability, whereas near-senescent cells that underwent mitosis despite the presence of uncapped telomeres did not. This suggests that these near-senescent cells had not yet acquired irreversible telomeric fusions. We propose a new model for telomere-initiated senescence where tolerance of telomere uncapping eventually results in irreversible non-telomeric DNA lesions leading to stable senescence. Paradoxically, our work reveals that senescence-associated tumor suppression from telomere shortening requires irreversible genome instability at the single-cell level, which suggests that interventions to repair telomeres in the pre-senescent state could prevent senescence and genome instability.
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Affiliation(s)
- Sabrina Ghadaouia
- Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), Montreal, QC, H2X 0A9, Canada.,Institut du cancer de Montréal, Montreal, QC, H2X 0A9, Canada
| | - Marc-Alexandre Olivier
- Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), Montreal, QC, H2X 0A9, Canada.,Institut du cancer de Montréal, Montreal, QC, H2X 0A9, Canada
| | - Aurélie Martinez
- Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), Montreal, QC, H2X 0A9, Canada.,Institut du cancer de Montréal, Montreal, QC, H2X 0A9, Canada
| | - Tibila Kientega
- Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), Montreal, QC, H2X 0A9, Canada.,Institut du cancer de Montréal, Montreal, QC, H2X 0A9, Canada
| | - Jian Qin
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC, H3A 0C7, Canada.,Jewish General Hospital, Lady Davis Institute, Montreal, QC, H3T 1E2, Canada
| | | | - Guillaume B Cardin
- Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), Montreal, QC, H2X 0A9, Canada.,Institut du cancer de Montréal, Montreal, QC, H2X 0A9, Canada
| | - Chantal Autexier
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC, H3A 0C7, Canada.,Jewish General Hospital, Lady Davis Institute, Montreal, QC, H3T 1E2, Canada
| | - Nicolas Malaquin
- Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), Montreal, QC, H2X 0A9, Canada.,Institut du cancer de Montréal, Montreal, QC, H2X 0A9, Canada
| | - Francis Rodier
- Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), Montreal, QC, H2X 0A9, Canada.,Institut du cancer de Montréal, Montreal, QC, H2X 0A9, Canada.,Department of Radiology, Radio-Oncology and Nuclear Medicine, Université de Montréal, Montreal, QC, H3T 1J4, Canada
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7
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Pan H, Kaur P, Barnes R, Detwiler AC, Sanford SL, Liu M, Xu P, Mahn C, Tang Q, Hao P, Bhattaram D, You C, Gu X, Lu W, Piehler J, Xu G, Weninger K, Riehn R, Opresko PL, Wang H. Structure, dynamics, and regulation of TRF1-TIN2-mediated trans- and cis-interactions on telomeric DNA. J Biol Chem 2021; 297:101080. [PMID: 34403696 PMCID: PMC8437784 DOI: 10.1016/j.jbc.2021.101080] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Revised: 07/30/2021] [Accepted: 08/12/2021] [Indexed: 01/17/2023] Open
Abstract
TIN2 is a core component of the shelterin complex linking double-stranded telomeric DNA-binding proteins (TRF1 and TRF2) and single-strand overhang-binding proteins (TPP1-POT1). In vivo, the large majority of TRF1 and TRF2 exist in complexes containing TIN2 but lacking TPP1/POT1; however, the role of TRF1-TIN2 interactions in mediating interactions with telomeric DNA is unclear. Here, we investigated DNA molecular structures promoted by TRF1-TIN2 interaction using atomic force microscopy (AFM), total internal reflection fluorescence microscopy (TIRFM), and the DNA tightrope assay. We demonstrate that the short (TIN2S) and long (TIN2L) isoforms of TIN2 facilitate TRF1-mediated DNA compaction (cis-interactions) and DNA-DNA bridging (trans-interactions) in a telomeric sequence- and length-dependent manner. On the short telomeric DNA substrate (six TTAGGG repeats), the majority of TRF1-mediated telomeric DNA-DNA bridging events are transient with a lifetime of ~1.95 s. On longer DNA substrates (270 TTAGGG repeats), TIN2 forms multiprotein complexes with TRF1 and stabilizes TRF1-mediated DNA-DNA bridging events that last on the order of minutes. Preincubation of TRF1 with its regulator protein Tankyrase 1 and the cofactor NAD+ significantly reduced TRF1-TIN2 mediated DNA-DNA bridging, whereas TIN2 protected the disassembly of TRF1-TIN2 mediated DNA-DNA bridging upon Tankyrase 1 addition. Furthermore, we showed that TPP1 inhibits TRF1-TIN2L-mediated DNA-DNA bridging. Our study, together with previous findings, supports a molecular model in which protein assemblies at telomeres are heterogeneous with distinct subcomplexes and full shelterin complexes playing distinct roles in telomere protection and elongation.
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Affiliation(s)
- Hai Pan
- Physics Department, North Carolina State University, Raleigh, North Carolina, USA
| | - Parminder Kaur
- Physics Department, North Carolina State University, Raleigh, North Carolina, USA; Center for Human Health and the Environment, North Carolina State University, Raleigh, North Carolina, USA
| | - Ryan Barnes
- Department of Environmental and Occupational Health, UPMC Hillman Cancer Center, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Ariana C Detwiler
- Department of Environmental and Occupational Health, UPMC Hillman Cancer Center, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Samantha Lynn Sanford
- Department of Environmental and Occupational Health, UPMC Hillman Cancer Center, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Ming Liu
- Physics Department, North Carolina State University, Raleigh, North Carolina, USA
| | - Pengning Xu
- Physics Department, North Carolina State University, Raleigh, North Carolina, USA
| | - Chelsea Mahn
- Physics Department, North Carolina State University, Raleigh, North Carolina, USA
| | - Qingyu Tang
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, North Carolina, USA
| | - Pengyu Hao
- Physics Department, North Carolina State University, Raleigh, North Carolina, USA
| | - Dhruv Bhattaram
- Department of Biomedical Engineering, Georgia Institute of Technology & Emory University of Medicine, Atlanta, Georgia, USA
| | - Changjiang You
- Department of Biology/Chemistry, Universität Osnabrück, Osnabrück, Germany
| | - Xinyun Gu
- College of Art and Sciences, New York University, New York City, New York, USA
| | - Warren Lu
- Department of Pathology at NYU Grossman School of Medicine, New York University, New York City, New York, USA
| | - Jacob Piehler
- Department of Biology/Chemistry, Universität Osnabrück, Osnabrück, Germany
| | - Guozhou Xu
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, North Carolina, USA
| | - Keith Weninger
- Physics Department, North Carolina State University, Raleigh, North Carolina, USA
| | - Robert Riehn
- Physics Department, North Carolina State University, Raleigh, North Carolina, USA
| | - Patricia L Opresko
- Department of Environmental and Occupational Health, UPMC Hillman Cancer Center, University of Pittsburgh, Pittsburgh, Pennsylvania, USA; Molecular Biophysics and Structural Biology Graduate Program, Carnegie Mellon University and the University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Hong Wang
- Physics Department, North Carolina State University, Raleigh, North Carolina, USA; Center for Human Health and the Environment, North Carolina State University, Raleigh, North Carolina, USA; Toxicology Program, North Carolina State University, Raleigh, North Carolina, USA.
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8
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Multifunctionality of the Telomere-Capping Shelterin Complex Explained by Variations in Its Protein Composition. Cells 2021; 10:cells10071753. [PMID: 34359923 PMCID: PMC8305809 DOI: 10.3390/cells10071753] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 07/03/2021] [Accepted: 07/09/2021] [Indexed: 12/31/2022] Open
Abstract
Protecting telomere from the DNA damage response is essential to avoid the entry into cellular senescence and organismal aging. The progressive telomere DNA shortening in dividing somatic cells, programmed during development, leads to critically short telomeres that trigger replicative senescence and thereby contribute to aging. In several organisms, including mammals, telomeres are protected by a protein complex named Shelterin that counteract at various levels the DNA damage response at chromosome ends through the specific function of each of its subunits. The changes in Shelterin structure and function during development and aging is thus an intense area of research. Here, we review our knowledge on the existence of several Shelterin subcomplexes and the functional independence between them. This leads us to discuss the possibility that the multifunctionality of the Shelterin complex is determined by the formation of different subcomplexes whose composition may change during aging.
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9
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Akincilar SC, Chan CHT, Ng QF, Fidan K, Tergaonkar V. Non-canonical roles of canonical telomere binding proteins in cancers. Cell Mol Life Sci 2021; 78:4235-4257. [PMID: 33599797 PMCID: PMC8164586 DOI: 10.1007/s00018-021-03783-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 12/28/2020] [Accepted: 01/29/2021] [Indexed: 02/06/2023]
Abstract
Reactivation of telomerase is a major hallmark observed in 90% of all cancers. Yet paradoxically, enhanced telomerase activity does not correlate with telomere length and cancers often possess short telomeres; suggestive of supplementary non-canonical roles that telomerase might play in the development of cancer. Moreover, studies have shown that aberrant expression of shelterin proteins coupled with their release from shortening telomeres can further promote cancer by mechanisms independent of their telomeric role. While targeting telomerase activity appears to be an attractive therapeutic option, this approach has failed in clinical trials due to undesirable cytotoxic effects on stem cells. To circumvent this concern, an alternative strategy could be to target the molecules involved in the non-canonical functions of telomeric proteins. In this review, we will focus on emerging evidence that has demonstrated the non-canonical roles of telomeric proteins and their impact on tumorigenesis. Furthermore, we aim to address current knowledge gaps in telomeric protein functions and propose future research approaches that can be undertaken to achieve this.
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Affiliation(s)
- Semih Can Akincilar
- Division of Cancer Genetics and Therapeutics, Laboratory of NFκB Signaling, Institute of Molecular and Cell Biology (IMCB), A*STAR (Agency for Science, Technology and Research), Proteos, 61, Biopolis Drive, Singapore, 138673, Singapore
| | - Claire Hian Tzer Chan
- Division of Cancer Genetics and Therapeutics, Laboratory of NFκB Signaling, Institute of Molecular and Cell Biology (IMCB), A*STAR (Agency for Science, Technology and Research), Proteos, 61, Biopolis Drive, Singapore, 138673, Singapore
| | - Qin Feng Ng
- Division of Cancer Genetics and Therapeutics, Laboratory of NFκB Signaling, Institute of Molecular and Cell Biology (IMCB), A*STAR (Agency for Science, Technology and Research), Proteos, 61, Biopolis Drive, Singapore, 138673, Singapore
| | - Kerem Fidan
- Division of Cancer Genetics and Therapeutics, Laboratory of NFκB Signaling, Institute of Molecular and Cell Biology (IMCB), A*STAR (Agency for Science, Technology and Research), Proteos, 61, Biopolis Drive, Singapore, 138673, Singapore
| | - Vinay Tergaonkar
- Division of Cancer Genetics and Therapeutics, Laboratory of NFκB Signaling, Institute of Molecular and Cell Biology (IMCB), A*STAR (Agency for Science, Technology and Research), Proteos, 61, Biopolis Drive, Singapore, 138673, Singapore.
- Department of Pathology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117593, Singapore.
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10
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Prasad R, Pal D, Mohammad W. Therapeutic Targets in Telomerase and Telomere Biology of Cancers. Indian J Clin Biochem 2020; 35:135-146. [PMID: 32226245 PMCID: PMC7093628 DOI: 10.1007/s12291-020-00876-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Telomeres play an important role to conserve genomic integrity by protecting the ends of chromosomes in normal cells. Since, their progressive shortening during successive cell division which lead to chromosomal instability. Notably, telomere length is perpetuated by telomerase in large majority of cancers, thereby ensure indefinite cell proliferation-a hallmark of cancer-and this unique feature has provided telomerase as the preferred target for drug development in cancer therapeutics. Cancer cells have acquired the potential to have telomere length maintenance by telomerase activation- up-regulation of hTERT gene expression in tumor cells is synchronized by multiple genetic and epigenetic modification mechanisms viz hTERT structural variants, hTERT promoter mutation and epigenetic modifications through hTERT promoter methylation which have been implicated in various cancers initiation and progression. In view of these facts, strategies have been made to target the underlining molecular mechanisms involved in telomerase reactivation as well as of telomere structure with special reference to distortion of sheltrin proteins. This review is focussed on extensive understanding of telomere and telomerase biology. which will provide indispensable informations for enhancing the efficiency of rational anticancer drug design. However, there is also an urgent need for better understanding of cell signalling pathways for alternative lengthening of telomere which is present in telomerase negative cancer for therapeutic targets.
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Affiliation(s)
- Rajendra Prasad
- Department of Biochemistry, MM Institute of Medical Science and Research, MM (Deemed to be University), Mullana, Ambala, Haryana 133207 India
| | - Deeksha Pal
- Department of Translational and Regenerative Medicine, Postgraduate Institute of Medical Education and Research, Chandigarh, 160012 India
| | - Wajid Mohammad
- Department of Biochemistry, MM Institute of Medical Science and Research, MM (Deemed to be University), Mullana, Ambala, Haryana 133207 India
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11
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Lee JH, Jung M, Hong J, Kim MK, Chung IK. Loss of RNA-binding protein HuR facilitates cellular senescence through posttranscriptional regulation of TIN2 mRNA. Nucleic Acids Res 2019; 46:4271-4285. [PMID: 29584879 PMCID: PMC5934620 DOI: 10.1093/nar/gky223] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Accepted: 03/15/2018] [Indexed: 02/07/2023] Open
Abstract
Cellular senescence can be induced by high levels of reactive oxygen species (ROS) produced by mitochondria. However, the mechanism by which elevated mitochondrial ROS levels are produced during replicative senescence is not yet fully understood. Here, we report that loss of the RNA-binding protein, human antigen R (HuR), during replicative senescence leads to an increase in ROS levels through enhanced mitochondrial localization of the telomeric protein TIN2. HuR binds to the 3′ untranslated region of TIN2 mRNA. This association decreases TIN2 protein levels by both destabilizing TIN2 mRNA and reducing its translation. Conversely, depletion of HuR levels enhances TIN2 expression, leading to increased mitochondrial targeting of TIN2. Mitochondrial localization of TIN2 increases ROS levels, which contributes to induction and maintenance of cellular senescence. Our findings provide compelling evidence for a novel role of HuR in controlling the process of cellular senescence by regulating TIN2-mediated mitochondrial ROS production, and for a useful therapeutic route for modulating intracellular ROS levels in treating both aging-related complications and cancer.
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Affiliation(s)
- Ji Hoon Lee
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, Korea
| | - Misun Jung
- Department of Integrated Omics for Biomedical Science, Yonsei University, Seoul 03722, Korea
| | - Juyeong Hong
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, Korea
| | - Mi Kyung Kim
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, Korea
| | - In Kwon Chung
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, Korea.,Department of Integrated Omics for Biomedical Science, Yonsei University, Seoul 03722, Korea
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12
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Klotho-Mediated Changes in Shelterin Complex Promote Cytotoxic Autophagy and Apoptosis in Amitriptyline-Treated Hippocampal Neuronal Cells. Mol Neurobiol 2019; 56:6952-6963. [DOI: 10.1007/s12035-019-1575-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2018] [Accepted: 03/20/2019] [Indexed: 12/29/2022]
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13
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Nelson ND, Dodson LM, Escudero L, Sukumar AT, Williams CL, Mihalek I, Baldan A, Baird DM, Bertuch AA. The C-Terminal Extension Unique to the Long Isoform of the Shelterin Component TIN2 Enhances Its Interaction with TRF2 in a Phosphorylation- and Dyskeratosis Congenita Cluster-Dependent Fashion. Mol Cell Biol 2018; 38:e00025-18. [PMID: 29581185 PMCID: PMC5974431 DOI: 10.1128/mcb.00025-18] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Accepted: 03/18/2018] [Indexed: 01/08/2023] Open
Abstract
TIN2 is central to the shelterin complex, linking the telomeric proteins TRF1 and TRF2 with TPP1/POT1. Mutations in TINF2, which encodes TIN2, that are found in dyskeratosis congenita (DC) result in very short telomeres and cluster in a region shared by the two TIN2 isoforms, TIN2S (short) and TIN2L (long). Here we show that TIN2L, but not TIN2S, is phosphorylated. TRF2 interacts more with TIN2L than TIN2S, and both the DC cluster and phosphorylation promote this enhanced interaction. The binding of TIN2L, but not TIN2S, is affected by TRF2-F120, which is also required for TRF2's interaction with end processing factors such as Apollo. Conversely, TRF1 interacts more with TIN2S than with TIN2L. A DC-associated mutation further reduces TIN2L-TRF1, but not TIN2S-TRF1, interaction. Cells overexpressing TIN2L or phosphomimetic TIN2L are permissive to telomere elongation, whereas cells overexpressing TIN2S or phosphodead TIN2L are not. Telomere lengths are unchanged in cell lines in which TIN2L expression has been eliminated by clustered regularly interspaced short palindromic repeat (CRISPR)/Cas9-mediated mutation. These results indicate that TIN2 isoforms are biochemically and functionally distinguishable and that shelterin composition could be fundamentally altered in patients with TINF2 mutations.
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Affiliation(s)
- Nya D Nelson
- Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, Texas, USA
- Division of Hematology/Oncology, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
| | - Lois M Dodson
- Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, Texas, USA
- Division of Hematology/Oncology, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
| | - Laura Escudero
- Division of Cancer and Genetics, School of Medicine, Cardiff University, Cardiff, United Kingdom
| | - Ann T Sukumar
- Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, Texas, USA
- Division of Hematology/Oncology, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
| | - Christopher L Williams
- Division of Hematology/Oncology, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
| | - Ivana Mihalek
- Bioinformatics Institute, Agency for Science Technology and Research, Singapore, Singapore
| | - Alessandro Baldan
- Division of Hematology/Oncology, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
| | - Duncan M Baird
- Division of Cancer and Genetics, School of Medicine, Cardiff University, Cardiff, United Kingdom
| | - Alison A Bertuch
- Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, Texas, USA
- Division of Hematology/Oncology, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
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14
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Fu F, Hu H, Yang S, Liang X. Effects of TIN2 on telomeres and chromosomes in the human gastric epithelial cell line GES-1. Oncol Lett 2018; 15:5161-5166. [PMID: 29552152 DOI: 10.3892/ol.2018.7927] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 12/15/2017] [Indexed: 01/13/2023] Open
Abstract
TERF1-interacting nuclear factor 2 (TIN2) is a key member of the protein complexes that protect telomeres. TIN2 contributes an important role in biological processes. In a previous study by the present authors, an association was reported between high TIN2 protein expression and gastric cancer. Therefore, it was hypothesized that abnormal TIN2 expression may cause the development of malignancies, including, gastric carcinomas. To investigate this hypothesis, the present study employed peptide nucleic acid fluorescence in situ hybridization technology to analyze the human gastric epithelial GES-1 cells with high TIN2 expression or inhibited TIN2 expression. The results indicated that GES-1 cell lines with high TIN2 expression exhibited greater telomere dysfunction-induced damage compared with GES-1 cell lines with inhibited TIN2 expression. Chromosome analysis indicated that GES-1 cells with high TIN2 expression exhibited 2.48±1.30 aberrant chromosomal changes per 100 cells, that may contribute to telomere DNA damage. Therefore, aberrant chromosomal alterations may provide a novel perspective for the pathogenesis of gastric cancer.
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Affiliation(s)
- Fan Fu
- Cancer Research Institute, Key Laboratory of Tumor Cellular and Molecular Pathology, College of Hunan, University of South China, Hengyang, Hunan 421001, P.R. China.,Department of Pathology, The Fourth Hospital of Changsha, Changsha, Hunan 410006, P.R. China
| | - Hua Hu
- Department of Pathology, The Second Affiliated Hospital, University of South China, Hengyang, Hunan 421001, P.R. China
| | - Shuai Yang
- Department of Pathology, The First Affiliated Hospital, University of South China, Hengyang, Hunan 421001, P.R. China
| | - Xiaoqiu Liang
- Cancer Research Institute, Key Laboratory of Tumor Cellular and Molecular Pathology, College of Hunan, University of South China, Hengyang, Hunan 421001, P.R. China
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15
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Zhang B, Zhang Y, Zou X, Chan AW, Zhang R, Lee TKW, Liu H, Lau EYT, Ho NPY, Lai PB, Cheung YS, To KF, Wong HK, Choy KW, Keng VW, Chow LM, Chan KK, Cheng AS, Ko BC. The CCCTC-binding factor (CTCF)-forkhead box protein M1 axis regulates tumour growth and metastasis in hepatocellular carcinoma. J Pathol 2017; 243:418-430. [PMID: 28862757 PMCID: PMC5725705 DOI: 10.1002/path.4976] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Revised: 08/16/2017] [Accepted: 08/24/2017] [Indexed: 12/21/2022]
Abstract
CCCTC‐binding factor (CTCF) is a DNA‐binding protein that interacts with a large number of highly divergent target sequences throughout the genome. It is implicated in a variety of functions, including chromatin organization and transcriptional control. The functional role of CTCF in tumour pathogenesis remains elusive. We showed that CTCF is frequently upregulated in a subset of primary hepatocellular carcinomas (HCCs) as compared with non‐tumoural liver. Overexpression of CTCF was associated with shorter disease‐free survival of patients. Short hairpin RNA (shRNA)‐mediated suppression of CTCF inhibited cell proliferation, motility and invasiveness in HCC cell lines; these effects were correlated with prominent reductions in the expression of telomerase reverse transcriptase (TERT), the shelterin complex member telomerase repeat‐binding factor 1, and forkhead box protein M1 (FOXM1). In contrast, upregulation of CTCF was positively correlated with FOXM1 and TERT expression in clinical HCC biopsies. Depletion of CTCF resulted in reduced motility and invasiveness in HCC cells that could be reversed by ectopic expression of FOXM1, suggesting that FOXM1 is one of the important downstream effectors of CTCF in HCC. Reporter gene analysis suggested that depletion of CTCF is associated with reduced FOXM1 and TERT promoter activity. Chromatin immunoprecipitation (ChIP)–polymerase chain reaction (PCR) analysis further revealed occupancy of the FOXM1 promoter by CTCF in vivo. Importantly, depletion of CTCF by shRNA significantly inhibited tumour progression and metastasis in HCC mouse models. Our work uncovered a novel functional role of CTCF in HCC pathogenesis, which suggests that targeting CTCF could be further explored as a potential therapeutic strategy for HCC. © 2017 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.
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Affiliation(s)
- Bin Zhang
- Department of Gastroenterology, Nanjing Drum Tower Hospital, Nanjing University, Nanjing, PR China
| | - Yajing Zhang
- The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen, PR China.,Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong, SAR, PR China.,State Key Laboratory of Chirosciences, The Hong Kong Polytechnic University, Hong Kong, SAR, PR China
| | - Xiaoping Zou
- Department of Gastroenterology, Nanjing Drum Tower Hospital, Nanjing University, Nanjing, PR China
| | - Anthony Wh Chan
- Department of Anatomical and Cellular Pathology, The Chinese University of Hong Kong, Hong Kong, SAR, PR China
| | - Rui Zhang
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong, SAR, PR China.,State Key Laboratory of Chirosciences, The Hong Kong Polytechnic University, Hong Kong, SAR, PR China
| | - Terence Kin-Wah Lee
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong, SAR, PR China.,State Key Laboratory of Chirosciences, The Hong Kong Polytechnic University, Hong Kong, SAR, PR China
| | - Hang Liu
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong, SAR, PR China
| | - Eunice Yuen-Ting Lau
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong, SAR, PR China
| | - Nicole Pui-Yu Ho
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong, SAR, PR China
| | - Paul Bs Lai
- Department of Surgery, The Chinese University of Hong Kong, Hong Kong, SAR, PR China
| | - Yue-Sun Cheung
- Department of Surgery, The Chinese University of Hong Kong, Hong Kong, SAR, PR China
| | - Ka-Fai To
- Department of Anatomical and Cellular Pathology, The Chinese University of Hong Kong, Hong Kong, SAR, PR China
| | - Hoi Kin Wong
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Hong Kong, SAR, PR China
| | - Kwong Wai Choy
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Hong Kong, SAR, PR China
| | - Vincent W Keng
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong, SAR, PR China
| | - Larry Mc Chow
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong, SAR, PR China.,State Key Laboratory of Chirosciences, The Hong Kong Polytechnic University, Hong Kong, SAR, PR China
| | - Kenrick Ky Chan
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong, SAR, PR China
| | - Alfred S Cheng
- School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong, SAR, PR China
| | - Ben Cb Ko
- The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen, PR China.,Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong, SAR, PR China.,State Key Laboratory of Chirosciences, The Hong Kong Polytechnic University, Hong Kong, SAR, PR China
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16
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Abstract
Aberrations in telomere biology are among the earliest events in prostate cancer tumorigenesis and continue during tumour progression. Substantial telomere shortening occurs in prostate cancer cells and high-grade prostatic intraepithelial neoplasia. Not all mechanisms of telomere shortening are understood, but oxidative stress from local inflammation might accelerate prostatic telomere loss. Critically short telomeres can drive the accumulation of tumour-promoting genomic alterations; however, continued telomere erosion is unsustainable and must be mitigated to ensure cancer cell survival and unlimited replication potential. Prostate cancers predominantly maintain telomeres by activating telomerase, but alternative mechanisms of telomere extension can occur in metastatic disease. Telomerase activity and telomere length assessment might be useful in prostate cancer diagnosis and prognosis. Telomere shortening in normal stromal cells has been associated with prostate cancer, whereas variable telomere lengths in prostate cancer cells and telomere shortening in cancer-associated stromal cells correlated with lethal disease. Single-agent telomerase-targeted treatments for solid cancers were ineffective in clinical trials but have not been investigated in prostate cancer and might be useful in combination with established regimens. Telomere-directed strategies have not been explored as extensively. Telomere deprotection strategies have the advantage of being effective in both telomerase-dependent and telomerase-independent cancers. Disruption of androgen receptor function in prostate cancer cells results in telomere dysfunction, indicating telomeres and telomerase as potential therapeutic targets in prostate cancer.
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17
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Wang Y, Wang X, Flores ER, Yu J, Chang S. Dysfunctional telomeres induce p53-dependent and independent apoptosis to compromise cellular proliferation and inhibit tumor formation. Aging Cell 2016; 15:646-60. [PMID: 27113195 PMCID: PMC4933665 DOI: 10.1111/acel.12476] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/24/2016] [Indexed: 01/09/2023] Open
Abstract
Aging is associated with progressive telomere shortening, resulting in the formation of dysfunctional telomeres that compromise tissue proliferation. However, dysfunctional telomeres can limit tumorigenesis by activating p53-dependent cellular senescence and apoptosis. While activation of both senescence and apoptosis is required for repress tumor formation, it is not clear which pathway is the major tumor suppressive pathway in vivo. In this study, we generated Eμ-myc; Pot1b(∆/∆) mouse to directly compare tumor formation under conditions in which either p53-dependent apoptosis or senescence is activated by telomeres devoid of the shelterin component Pot1b. We found that activation of p53-dependent apoptosis plays a more critical role in suppressing lymphoma formation than p53-dependent senescence. In addition, we found that telomeres in Pot1b(∆/∆) ; p53(-/-) mice activate an ATR-Chk1-dependent DNA damage response to initiate a robust p53-independent, p73-dependent apoptotic pathway that limited stem cell proliferation but suppressed B-cell lymphomagenesis. Our results demonstrate that in mouse models, both p53-dependent and p53-independent apoptosis are important to suppressing tumor formation.
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Affiliation(s)
- Yang Wang
- Department of Laboratory Medicine Yale University School of Medicine New Haven CT USA
| | - Xinwei Wang
- University of Pittsburgh School of Medicine University of Pittsburgh Cancer Institute Hillman Cancer Center Research Pavilion Pittsburgh PA USA
| | - Elsa R. Flores
- Department of Molecular & Cellular Oncology Department of Translational Molecular Pathology Graduate School of Biomedical Sciences U.T. MD Anderson Cancer Center Houston TX USA
| | - Jian Yu
- University of Pittsburgh School of Medicine University of Pittsburgh Cancer Institute Hillman Cancer Center Research Pavilion Pittsburgh PA USA
| | - Sandy Chang
- Department of Laboratory Medicine Yale University School of Medicine New Haven CT USA
- Departments of Pathology and Molecular Biophysics and Biochemistry Yale University School of Medicine New Haven CT USA
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18
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Sarek G, Marzec P, Margalef P, Boulton SJ. Molecular basis of telomere dysfunction in human genetic diseases. Nat Struct Mol Biol 2015; 22:867-74. [PMID: 26581521 DOI: 10.1038/nsmb.3093] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 08/23/2015] [Indexed: 01/28/2023]
Abstract
Mutations in genes encoding proteins required for telomere structure, replication, repair and length maintenance are associated with several debilitating human genetic disorders. These complex telomere biology disorders (TBDs) give rise to critically short telomeres that affect the homeostasis of multiple organs. Furthermore, genome instability is often a hallmark of telomere syndromes, which are associated with increased cancer risk. Here, we summarize the molecular causes and cellular consequences of disease-causing mutations associated with telomere dysfunction.
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Affiliation(s)
- Grzegorz Sarek
- DNA Damage Response Laboratory, Francis Crick Institute, South Mimms, UK
| | - Paulina Marzec
- DNA Damage Response Laboratory, Francis Crick Institute, South Mimms, UK
| | - Pol Margalef
- DNA Damage Response Laboratory, Francis Crick Institute, South Mimms, UK
| | - Simon J Boulton
- DNA Damage Response Laboratory, Francis Crick Institute, South Mimms, UK
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19
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Frank AK, Tran DC, Qu RW, Stohr BA, Segal DJ, Xu L. The Shelterin TIN2 Subunit Mediates Recruitment of Telomerase to Telomeres. PLoS Genet 2015; 11:e1005410. [PMID: 26230315 PMCID: PMC4521702 DOI: 10.1371/journal.pgen.1005410] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Accepted: 07/02/2015] [Indexed: 11/26/2022] Open
Abstract
Dyskeratosis Congenita (DC) is a heritable multi-system disorder caused by abnormally short telomeres. Clinically diagnosed by the mucocutaneous symptoms, DC patients are at high risk for bone marrow failure, pulmonary fibrosis, and multiple types of cancers. We have recapitulated the most common DC-causing mutation in the shelterin component TIN2 by introducing a TIN2-R282H mutation into cultured telomerase-positive human cells via a knock-in approach. The resulting heterozygous TIN2-R282H mutation does not perturb occupancy of other shelterin components on telomeres, result in activation of telomeric DNA damage signaling or exhibit other characteristics indicative of a telomere deprotection defect. Using a novel assay that monitors the frequency and extension rate of telomerase activity at individual telomeres, we show instead that telomerase elongates telomeres at a reduced frequency in TIN2-R282H heterozygous cells; this recruitment defect is further corroborated by examining the effect of this mutation on telomerase-telomere co-localization. These observations suggest a direct role for TIN2 in mediating telomere length through telomerase, separable from its role in telomere protection. The shelterin complex protects telomeres from being processed by the DNA damage repair machinery, and also regulates telomerase access and activity at telomeres. The only shelterin subunit known to promote telomerase function is TPP1, which mediates telomerase recruitment to telomeres and stimulates telomerase processivity. Mutations in shelterin components cause Dyskeratosis Congenita (DC) and related disease syndromes due to the inability to maintain telomere homeostasis. In this study, we have identified TIN2-R282H, the most common DC-causing mutation in shelterin subunit TIN2, as a separation-of-function mutant which impairs telomerase recruitment to telomeres, but not chromosome end protection. The telomerase recruitment defect conferred by TIN2-R282H is likely through a mechanism independent of TIN2’s role in anchoring TPP1 at telomeres, since TPP1 localization to telomeres is unaffected by the mutation.
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Affiliation(s)
- Amanda K. Frank
- Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, California, United States of America
| | - Duy C. Tran
- Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, California, United States of America
| | - Roy W. Qu
- Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, California, United States of America
| | - Bradley A. Stohr
- Department of Pathology, University of California, San Francisco, San Francisco, California, United States of America
| | - David J. Segal
- Genome Center and Department of Biochemistry and Molecular Medicine, University of California, Davis, Davis, California, United States of America
| | - Lifeng Xu
- Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, California, United States of America
- * E-mail:
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20
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Luo Z, Feng X, Wang H, Xu W, Zhao Y, Ma W, Jiang S, Liu D, Huang J, Songyang Z. Mir-23a induces telomere dysfunction and cellular senescence by inhibiting TRF2 expression. Aging Cell 2015; 14:391-9. [PMID: 25753893 PMCID: PMC4406668 DOI: 10.1111/acel.12304] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/22/2014] [Indexed: 12/28/2022] Open
Abstract
Telomeric repeat binding factor 2 (TRF2) is essential for telomere maintenance and has been implicated in DNA damage response and aging. Telomere dysfunction induced by TRF2 inhibition can accelerate cellular senescence in human fibroblasts. While previous work has demonstrated that a variety of factors can regulate TRF2 expression transcriptionally and post-translationally, whether microRNAs (miRNAs) also participate in post-transcriptionally modulating TRF2 levels remains largely unknown. To better understand the regulatory pathways that control TRF2, we carried out a large-scale luciferase reporter screen using a miRNA expression library and identified four miRNAs that could target human TRF2 and significantly reduce the level of endogenous TRF2 proteins. In particular, our data revealed that miR-23a could directly target the 3′ untranslated region (3′UTR) of TRF2. Overexpression of miR-23a not only reduced telomere-bound TRF2 and increased telomere dysfunction-induced foci (TIFs), but also accelerated senescence of human fibroblast cells, which could be rescued by ectopically expressed TRF2. Our findings demonstrate that TRF2 is a specific target of miR-23a, and uncover a previously unknown role for miR-23a in telomere regulation and cellular senescence.
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Affiliation(s)
- Zhenhua Luo
- Key Laboratory of Gene Engineering of the Ministry of Education Key Laboratory of Reproductive Medicine of Guangdong Province School of Life Sciences and the First Affiliated Hospital Sun Yat‐sen University Guangzhou 510275 China
- SYSU‐BCM Joint Research Center for Biomedical Sciences and Institute of Healthy Aging Research School of Life Sciences Sun Yat‐sen University Guangzhou 510275 China
| | - Xuyang Feng
- Key Laboratory of Gene Engineering of the Ministry of Education Key Laboratory of Reproductive Medicine of Guangdong Province School of Life Sciences and the First Affiliated Hospital Sun Yat‐sen University Guangzhou 510275 China
- SYSU‐BCM Joint Research Center for Biomedical Sciences and Institute of Healthy Aging Research School of Life Sciences Sun Yat‐sen University Guangzhou 510275 China
| | - Haoli Wang
- Key Laboratory of Gene Engineering of the Ministry of Education Key Laboratory of Reproductive Medicine of Guangdong Province School of Life Sciences and the First Affiliated Hospital Sun Yat‐sen University Guangzhou 510275 China
| | - Weiyi Xu
- Key Laboratory of Gene Engineering of the Ministry of Education Key Laboratory of Reproductive Medicine of Guangdong Province School of Life Sciences and the First Affiliated Hospital Sun Yat‐sen University Guangzhou 510275 China
| | - Yong Zhao
- Key Laboratory of Gene Engineering of the Ministry of Education Key Laboratory of Reproductive Medicine of Guangdong Province School of Life Sciences and the First Affiliated Hospital Sun Yat‐sen University Guangzhou 510275 China
- SYSU‐BCM Joint Research Center for Biomedical Sciences and Institute of Healthy Aging Research School of Life Sciences Sun Yat‐sen University Guangzhou 510275 China
| | - Wenbin Ma
- Key Laboratory of Gene Engineering of the Ministry of Education Key Laboratory of Reproductive Medicine of Guangdong Province School of Life Sciences and the First Affiliated Hospital Sun Yat‐sen University Guangzhou 510275 China
- SYSU‐BCM Joint Research Center for Biomedical Sciences and Institute of Healthy Aging Research School of Life Sciences Sun Yat‐sen University Guangzhou 510275 China
| | - Songshan Jiang
- Key Laboratory of Gene Engineering of the Ministry of Education Key Laboratory of Reproductive Medicine of Guangdong Province School of Life Sciences and the First Affiliated Hospital Sun Yat‐sen University Guangzhou 510275 China
| | - Dan Liu
- Cell‐Based Assay Screening Core One Baylor Plaza Houston TX 77030 USA
- Dan L. Duncan Cancer Center One Baylor Plaza Houston TX 77030 USA
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology Baylor College of Medicine One Baylor Plaza Houston TX 77030 USA
| | - Junjiu Huang
- Key Laboratory of Gene Engineering of the Ministry of Education Key Laboratory of Reproductive Medicine of Guangdong Province School of Life Sciences and the First Affiliated Hospital Sun Yat‐sen University Guangzhou 510275 China
- SYSU‐BCM Joint Research Center for Biomedical Sciences and Institute of Healthy Aging Research School of Life Sciences Sun Yat‐sen University Guangzhou 510275 China
| | - Zhou Songyang
- Key Laboratory of Gene Engineering of the Ministry of Education Key Laboratory of Reproductive Medicine of Guangdong Province School of Life Sciences and the First Affiliated Hospital Sun Yat‐sen University Guangzhou 510275 China
- SYSU‐BCM Joint Research Center for Biomedical Sciences and Institute of Healthy Aging Research School of Life Sciences Sun Yat‐sen University Guangzhou 510275 China
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology Baylor College of Medicine One Baylor Plaza Houston TX 77030 USA
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21
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Harland JL, Chang YT, Moser BA, Nakamura TM. Tpz1-Ccq1 and Tpz1-Poz1 interactions within fission yeast shelterin modulate Ccq1 Thr93 phosphorylation and telomerase recruitment. PLoS Genet 2014; 10:e1004708. [PMID: 25330395 PMCID: PMC4199508 DOI: 10.1371/journal.pgen.1004708] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Accepted: 08/26/2014] [Indexed: 11/22/2022] Open
Abstract
In both fission yeast and humans, the shelterin complex plays central roles in regulation of telomerase recruitment, protection of telomeres against DNA damage response factors, and formation of heterochromatin at telomeres. While shelterin is essential for limiting activation of the DNA damage checkpoint kinases ATR and ATM at telomeres, these kinases are required for stable maintenance of telomeres. In fission yeast, Rad3ATR and Tel1ATM kinases are redundantly required for telomerase recruitment, since Rad3ATR/Tel1ATM-dependent phosphorylation of the shelterin subunit Ccq1 at Thr93 promotes interaction between Ccq1 and the telomerase subunit Est1. However, it remained unclear how protein-protein interactions within the shelterin complex (consisting of Taz1, Rap1, Poz1, Tpz1, Pot1 and Ccq1) contribute to the regulation of Ccq1 Thr93 phosphorylation and telomerase recruitment. In this study, we identify domains and amino acid residues that are critical for mediating Tpz1-Ccq1 and Tpz1-Poz1 interaction within the fission yeast shelterin complex. Using separation of function Tpz1 mutants that maintain Tpz1-Pot1 interaction but specifically disrupt either Tpz1-Ccq1 or Tpz1-Poz1 interaction, we then establish that Tpz1-Ccq1 interaction promotes Ccq1 Thr93 phosphorylation, telomerase recruitment, checkpoint inhibition and telomeric heterochromatin formation. Furthermore, we demonstrate that Tpz1-Poz1 interaction promotes telomere association of Poz1, and loss of Poz1 from telomeres leads to increases in Ccq1 Thr93 phosphorylation and telomerase recruitment, and telomeric heterochromatin formation defect. In addition, our studies establish that Tpz1-Poz1 and Tpz1-Ccq1 interactions redundantly fulfill the essential telomere protection function of the shelterin complex, since simultaneous loss of both interactions caused immediate loss of cell viability for the majority of cells and generation of survivors with circular chromosomes. Based on these findings, we suggest that the negative regulatory function of Tpz1-Poz1 interaction works upstream of Rad3ATR kinase, while Tpz1-Ccq1 interaction works downstream of Rad3ATR kinase to facilitate Ccq1 Thr93 phosphorylation and telomerase recruitment. Proper maintenance of telomeres is essential for maintaining genomic stability, and genomic instability caused by dysfunctional telomeres could lead to accumulation of mutations that may drive tumor formation. Telomere dysfunction has also been linked to premature aging caused by depletion of stem cells. Therefore, it is important to understand how cells ensure proper maintenance of telomeres. Mammalian cells and fission yeast cells utilize an evolutionarily conserved multi-subunit telomere protection complex called shelterin to ensure protection against telomere fusions by DNA repair factors and cell cycle arrest by DNA damage checkpoint kinases. However, previous studies have not yet fully established how protein-protein interactions within the shelterin complex contribute to the regulation of DNA damage checkpoint signaling and telomerase recruitment. By utilizing separation of function mutations that specifically disrupt either Tpz1-Ccq1 or Tpz1-Poz1 interaction within the fission yeast shelterin, we establish that Tpz1-Ccq1 interaction is essential for phosphorylation of Ccq1 by the DNA damage checkpoint kinases Rad3ATR and Tel1ATM that is needed for telomerase recruitment to telomeres, while Tpz1-Poz1 interaction prevents Ccq1 phosphorylation by promoting Poz1 association with telomeres. These findings thus establish for the first time how protein-protein interactions within the shelterin complex modulate checkpoint kinase-dependent phosphorylation essential for telomerase recruitment.
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Affiliation(s)
- Jennifer L. Harland
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Ya-Ting Chang
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Bettina A. Moser
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Toru M. Nakamura
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, Illinois, United States of America
- * E-mail:
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22
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Jehi SE, Wu F, Li B. Trypanosoma brucei TIF2 suppresses VSG switching by maintaining subtelomere integrity. Cell Res 2014; 24:870-85. [PMID: 24810301 DOI: 10.1038/cr.2014.60] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Revised: 03/11/2014] [Accepted: 04/07/2014] [Indexed: 12/21/2022] Open
Abstract
Subtelomeres consist of sequences adjacent to telomeres and contain genes involved in important cellular functions, as subtelomere instability is associated with several human diseases. Balancing between subtelomere stability and plasticity is particularly important for Trypanosoma brucei, a protozoan parasite that causes human African trypanosomiasis. T. brucei regularly switches its major variant surface antigen, variant surface glycoprotein (VSG), to evade the host immune response, and VSGs are expressed exclusively from subtelomeres in a strictly monoallelic fashion. Telomere proteins are important for protecting chromosome ends from illegitimate DNA processes. However, whether they contribute to subtelomere integrity and stability has not been well studied. We have identified a novel T. brucei telomere protein, T. brucei TRF-Interacting Factor 2 (TbTIF2), as a functional homolog of mammalian TIN2. A transient depletion of TbTIF2 led to an elevated VSG switching frequency and an increased amount of DNA double-strand breaks (DSBs) in both active and silent subtelomeric bloodstream form expression sites (BESs). Therefore, TbTIF2 plays an important role in VSG switching regulation and is important for subtelomere integrity and stability. TbTIF2 depletion increased the association of TbRAD51 with the telomeric and subtelomeric chromatin, and TbRAD51 deletion further increased subtelomeric DSBs in TbTIF2-depleted cells, suggesting that TbRAD51-mediated DSB repair is the underlying mechanism of subsequent VSG switching. Surprisingly, significantly more TbRAD51 associated with the active BES than with the silent BESs upon TbTIF2 depletion, and TbRAD51 deletion induced much more DSBs in the active BES than in the silent BESs in TbTIF2-depleted cells, suggesting that TbRAD51 preferentially repairs DSBs in the active BES.
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Affiliation(s)
- Sanaa E Jehi
- Department of Biological, Geological, and Environmental Sciences, Center for Gene Regulation in Health and Disease, Cleveland State University, Cleveland, OH 44115, USA
| | - Fan Wu
- Department of Biological, Geological, and Environmental Sciences, Center for Gene Regulation in Health and Disease, Cleveland State University, Cleveland, OH 44115, USA
| | - Bibo Li
- 1] Department of Biological, Geological, and Environmental Sciences, Center for Gene Regulation in Health and Disease, Cleveland State University, Cleveland, OH 44115, USA [2] The Rockefeller University, New York, NY 10065, USA [3] Department of Molecular Genetics, Cleveland Clinic Lerner Research Institute, Cleveland, OH 44195, USA [4] Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH 44106, USA
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23
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Shim G, Ricoul M, Hempel WM, Azzam EI, Sabatier L. Crosstalk between telomere maintenance and radiation effects: A key player in the process of radiation-induced carcinogenesis. MUTATION RESEARCH. REVIEWS IN MUTATION RESEARCH 2014; 760:S1383-5742(14)00002-7. [PMID: 24486376 PMCID: PMC4119099 DOI: 10.1016/j.mrrev.2014.01.001] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Revised: 01/14/2014] [Accepted: 01/22/2014] [Indexed: 02/06/2023]
Abstract
It is well established that ionizing radiation induces chromosomal damage, both following direct radiation exposure and via non-targeted (bystander) effects, activating DNA damage repair pathways, of which the proteins are closely linked to telomeric proteins and telomere maintenance. Long-term propagation of this radiation-induced chromosomal damage during cell proliferation results in chromosomal instability. Many studies have shown the link between radiation exposure and radiation-induced changes in oxidative stress and DNA damage repair in both targeted and non-targeted cells. However, the effect of these factors on telomeres, long established as guardians of the genome, still remains to be clarified. In this review, we will focus on what is known about how telomeres are affected by exposure to low- and high-LET ionizing radiation and during proliferation, and will discuss how telomeres may be a key player in the process of radiation-induced carcinogenesis.
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24
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Zhou J, Richardson M, Reddy V, Menon M, Barrack ER, Reddy GPV, Kim SH. Structural and functional association of androgen receptor with telomeres in prostate cancer cells. Aging (Albany NY) 2013; 5:3-17. [PMID: 23363843 PMCID: PMC3616228 DOI: 10.18632/aging.100524] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Telomeres protect the ends of linear chromosomes from being recognized as damaged DNA, and telomere stability is required for genome stability. Here we demonstrate that telomere stability in androgen receptor (AR)-positive LNCaP human prostate cancer cells is dependent on AR and androgen, as AR inactivation by AR antagonist bicalutamide (Casodex), AR-knockdown, or androgen-depletion caused telomere dysfunction, and the effect of androgen-depletion or Casodex was blocked by the addition of androgen. Notably, neither actinomycin D nor cycloheximide blocked the DNA damage response to Casodex, indicating that the role of AR in telomere stability is independent of its role in transcription. We also demonstrate that AR is a component of telomeres, as AR-bound chromatin contains telomeric DNA, and telomeric chromatin contains AR. Importantly, AR inactivation by Casodex caused telomere aberrations, including multiple abnormal telomere signals, remindful of a fragile telomere phenotype that has been described previously to result from defective telomere DNA replication. We suggest that AR plays an important role in telomere stability and replication of telomere DNA in prostate cancer cells, and that AR inactivation-mediated telomere dysfunction may contribute to genomic instability and progression of prostate cancer cells.
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Affiliation(s)
- Junying Zhou
- Vattikuti Urology Institute, Henry Ford Hospital, Detroit, MI 48202, USA
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25
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Kim SH, Barrack ER, Prem Veer Reddy G. Telomerase turns telomere dysfunction from bad to worse. Asian J Androl 2012; 14:665-6. [DOI: 10.1038/aja.2012.37] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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26
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Conditional TRF1 knockout in the hematopoietic compartment leads to bone marrow failure and recapitulates clinical features of dyskeratosis congenita. Blood 2012; 120:2990-3000. [PMID: 22932806 DOI: 10.1182/blood-2012-03-418038] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
TRF1 is part of the shelterin complex, which binds telomeres and it is essential for their protection. Ablation of TRF1 induces sister telomere fusions and aberrant numbers of telomeric signals associated with telomere fragility. Dyskeratosis congenita is characterized by a mucocutaneous triad, bone marrow failure (BMF), and presence of short telomeres because of mutations in telomerase. A subset of patients, however, show mutations in the shelterin component TIN2, a TRF1-interacting protein, presenting a more severe phenotype and presence of very short telomeres despite normal telomerase activity. Allelic variations in TRF1 have been found associated with BMF. To address a possible role for TRF1 dysfunction in BMF, here we generated a mouse model with conditional TRF1 deletion in the hematopoietic system. Chronic TRF1 deletion results in increased DNA damage and cellular senescence, but not increased apoptosis, in BM progenitor cells, leading to severe aplasia. Importantly, increased compensatory proliferation of BM stem cells is associated with rapid telomere shortening and further increase in senescent cells in vivo, providing a mechanism for the very short telomeres of human patients with mutations in the shelterin TIN2. Together, these results represent proof of principle that mutations in TRF1 lead to the main clinical features of BMF.
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27
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Walker JR, Zhu XD. Post-translational modifications of TRF1 and TRF2 and their roles in telomere maintenance. Mech Ageing Dev 2012; 133:421-34. [PMID: 22634377 DOI: 10.1016/j.mad.2012.05.002] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Revised: 04/27/2012] [Accepted: 05/04/2012] [Indexed: 11/29/2022]
Abstract
Telomeres, heterochromatic structures, found at the ends of linear eukaryotic chromosomes, function to protect natural chromosome ends from nucleolytic attack. Human telomeric DNA is bound by a telomere-specific six-subunit protein complex, termed shelterin/telosome. The shelterin subunits TRF1 and TRF2 bind in a sequence-specific manner to double-stranded telomeric DNA, providing a vital platform for recruitment of additional shelterin proteins as well as non-shelterin factors crucial for the maintenance of telomere length and structure. Both TRF1 and TRF2 are engaged in multiple roles at telomeres including telomere protection, telomere replication, sister telomere resolution and telomere length maintenance. Regulation of TRF1 and TRF2 in these various processes is controlled by post-translational modifications, at times in a cell-cycle-dependent manner, affecting key functions such as DNA binding, dimerization, localization, degradation and interactions with other proteins. Here we review the post-translational modifications of TRF1 and TRF2 and discuss the mechanisms by which these modifications contribute to the function of these two proteins.
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Affiliation(s)
- John R Walker
- Department of Biology, LSB438, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4K1, Canada
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28
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Bilsland AE, Cairney CJ, Keith WN. Targeting the telomere and shelterin complex for cancer therapy: current views and future perspectives. J Cell Mol Med 2012; 15:179-86. [PMID: 21199331 PMCID: PMC3822786 DOI: 10.1111/j.1582-4934.2010.01253.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Aberrant telomere homeostasis is essential for cell immortality, enabling cells to evade telomere dependent senescence. Disruption of telomere structure and function in cancer cells is highly toxic as shown by detailed pre-clinical evaluation of telomerase inhibitors. Under telomerase inhibition, cells must divide sufficiently frequently to allow one or more telomeres to shorten to an unprotected length. Functioning telomeres are disguised from the DNA damage machinery by DNA remodelling and other activities of the telomere binding complex shelterin. Direct interference with shelterin has been shown to result in cell killing and small molecules directly targeting telomere DNA also have anti-tumour effects partially dependent on shelterin disruption. However, shelterin components have not generally been regarded as therapeutic targets in their own right. In this review, we explore the possibilities for therapeutic targeting of the shelterin complex.
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Affiliation(s)
- Alan E Bilsland
- University of Glasgow, Institute of Cancer Sciences, Beatson Laboratories, Bearsden, Glasgow, UK
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29
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Stewart JA, Chaiken MF, Wang F, Price CM. Maintaining the end: roles of telomere proteins in end-protection, telomere replication and length regulation. Mutat Res 2012; 730:12-9. [PMID: 21945241 PMCID: PMC3256267 DOI: 10.1016/j.mrfmmm.2011.08.011] [Citation(s) in RCA: 144] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Revised: 08/15/2011] [Accepted: 08/17/2011] [Indexed: 11/16/2022]
Abstract
Chromosome end protection is essential to protect genome integrity. Telomeres, tracts of repetitive DNA sequence and associated proteins located at the chromosomal terminus, serve to safeguard the ends from degradation and unwanted double strand break repair. Due to the essential nature of telomeres in protecting the genome, a number of unique proteins have evolved to ensure that telomere length and structure are preserved. The inability to properly maintain telomeres can lead to diseases such as dyskeratosis congenita, pulmonary fibrosis and cancer. In this review, we will discuss the known functions of mammalian telomere-associated proteins, their role in telomere replication and length regulation and how these processes relate to genome instability and human disease.
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Affiliation(s)
- Jason A. Stewart
- Department of Cancer and Cell Biology, University of Cincinnati, Cincinnati, Ohio 45267, USA
| | - Mary F. Chaiken
- Department of Cancer and Cell Biology, University of Cincinnati, Cincinnati, Ohio 45267, USA
| | - Feng Wang
- Department of Cancer and Cell Biology, University of Cincinnati, Cincinnati, Ohio 45267, USA
| | - Carolyn M. Price
- Department of Cancer and Cell Biology, University of Cincinnati, Cincinnati, Ohio 45267, USA
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30
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Yang D, He Q, Kim H, Ma W, Songyang Z. TIN2 protein dyskeratosis congenita missense mutants are defective in association with telomerase. J Biol Chem 2011; 286:23022-30. [PMID: 21536674 PMCID: PMC3123070 DOI: 10.1074/jbc.m111.225870] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2011] [Revised: 04/29/2011] [Indexed: 12/18/2022] Open
Abstract
Dyskeratosis congenita (DC) is a progressive and heterogeneous congenital disorder that affects multiple systems and is characterized by bone marrow failure and a triad of abnormal skin pigmentation, nail dystrophy, and oral leukoplakia. One common feature for all DC patients is abnormally short telomeres and defects in telomere biology. Most of the known DC mutations have been found to affect core components of the telomerase holoenzyme. Recently, multiple mutations in the gene encoding the telomeric protein TIN2 have been identified in DC patients with intact telomerase genes, but the molecular mechanisms underlying TIN2 mutation-mediated DC remain unknown. Here, we demonstrate that ectopic expression of TIN2 with DC missense mutations in human cells led to accelerated telomere shortening, similar to the telomere phenotypes found in DC patients. However, this telomere shortening was not accompanied by changes in total telomerase activity, localization of TIN2, or telomere end protection status. Interestingly, we found TIN2 to participate in the TPP1-dependent recruitment of telomerase activity. Furthermore, DC mutations in TIN2 led to its decreased ability to associate with TERC and telomerase activity. Taken together, our data suggest that TIN2 mutations in DC may compromise the telomere recruitment of telomerase, leading to telomere shortening and the associated pathogenesis.
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Affiliation(s)
- Dong Yang
- the Verna and Mars McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030
| | - Quanyuan He
- the Verna and Mars McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030
| | - Hyeung Kim
- the Verna and Mars McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030
| | - Wenbin Ma
- From the State Key Laboratory for Biocontrol, Sun Yat-Sen University, Guangzhou 510275, China and
- the Verna and Mars McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030
| | - Zhou Songyang
- From the State Key Laboratory for Biocontrol, Sun Yat-Sen University, Guangzhou 510275, China and
- the Verna and Mars McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030
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31
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Transcriptional activation of TINF2, a gene encoding the telomere-associated protein TIN2, by Sp1 and NF-κB factors. PLoS One 2011; 6:e21333. [PMID: 21731707 PMCID: PMC3121743 DOI: 10.1371/journal.pone.0021333] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2011] [Accepted: 05/28/2011] [Indexed: 11/19/2022] Open
Abstract
The expression of the telomere-associated protein TIN2 has been shown to be essential for early embryonic development in mice and for development of a variety of human malignancies. Recently, germ-line mutations in TINF2, which encodes for the TIN2 protein, have been identified in a number of patients with bone-marrow failure syndromes. Yet, the molecular mechanisms that regulate TINF2 expression are largely unknown. To elucidate the mechanisms involved in human TINF2 regulation, we cloned a 2.7 kb genomic DNA fragment containing the putative promoter region and, through deletion analysis, identified a 406 bp region that functions as a minimal promoter. This promoter proximal region is predicted to contain several putative Sp1 and NF-κB binding sites based on bioinformatic analysis. Direct binding of the Sp1 and NF-κB transcription factors to the TIN2 promoter sequence was demonstrated by electrophoretic mobility shift assay (EMSA) and/or chromatin immunoprecipitation (ChIP) assays. Transfection of a plasmid carrying the Sp1 transcription factor into Sp-deficient SL2 cells strongly activated TIN2 promoter-driven luciferase reporter expression. Similarly, the NF-κB molecules p50 and p65 were found to strongly activate luciferase expression in NF-κB knockout MEFs. Mutating the predicted transcription factor binding sites effectively reduced TIN2 promoter activity. Various known chemical inhibitors of Sp1 and NF-κB could also strongly inhibit TIN2 transcriptional activity. Collectively, our results demonstrate the important roles that Sp1 and NF-κB play in regulating the expression of the human telomere-binding protein TIN2, which can shed important light on its possible role in causing various forms of human diseases and cancers.
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32
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Lee OH, Kim H, He Q, Baek HJ, Yang D, Chen LY, Liang J, Chae HK, Safari A, Liu D, Songyang Z. Genome-wide YFP fluorescence complementation screen identifies new regulators for telomere signaling in human cells. Mol Cell Proteomics 2010; 10:M110.001628. [PMID: 21044950 DOI: 10.1074/mcp.m110.001628] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Detection of low-affinity or transient interactions can be a bottleneck in our understanding of signaling networks. To address this problem, we developed an arrayed screening strategy based on protein complementation to systematically investigate protein-protein interactions in live human cells, and performed a large-scale screen for regulators of telomeres. Maintenance of vertebrate telomeres requires the concerted action of members of the Telomere Interactome, built upon the six core telomeric proteins TRF1, TRF2, RAP1, TIN2, TPP1, and POT1. Of the ∼12,000 human proteins examined, we identified over 300 proteins that associated with the six core telomeric proteins. The majority of the identified proteins have not been previously linked to telomere biology, including regulators of post-translational modifications such as protein kinases and ubiquitin E3 ligases. Results from this study shed light on the molecular niche that is fundamental to telomere regulation in humans, and provide a valuable tool to investigate signaling pathways in mammalian cells.
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Affiliation(s)
- Ok-Hee Lee
- Severance Hospital Integrative Research Institute for Cerebral and Cardiovascular Disease, Yonsei University Health System, Seoul, Korea
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33
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Giraud-Panis MJ, Pisano S, Poulet A, Le Du MH, Gilson E. Structural identity of telomeric complexes. FEBS Lett 2010; 584:3785-99. [PMID: 20696167 DOI: 10.1016/j.febslet.2010.08.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2010] [Revised: 08/02/2010] [Accepted: 08/02/2010] [Indexed: 02/01/2023]
Abstract
A major issue in telomere research is to understand how the integrity of chromosome ends is controlled. Although several nucleoprotein complexes have been described at the telomeres of different organisms, it is still unclear how they confer a structural identity to chromosome ends in order to mask them from DNA repair and to ensure their proper replication. In this review, we describe how telomeric nucleoprotein complexes are structured, comparing different organisms and trying to link these structures to telomere biology. It emerges that telomeres are formed by a complex and specific network of interactions between DNA, RNA and proteins. The fact that these interactions and associated activities are reinforcing each other might help to guaranty the robustness of telomeric functions across the cell cycle and in the event of cellular perturbations. We propose that telomeric nucleoprotein complexes orient cell fate through dynamic transitions in their structures and their organization.
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Affiliation(s)
- Marie-Josèphe Giraud-Panis
- University de Nice, Laboratory of Biology and Pathology of Genomes, UMR 6267 CNRS U998 INSERM, Faculté de Médecine, Nice, France
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Abstract
The linear nature of eukaryotic chromosomes necessitates protection of their physical ends, the telomeres, because the DNA-repair machinery can misconstrue the ends as double-stranded DNA breaks. Thus, protection is crucial for avoiding an unwarranted DNA-damage response that could have catastrophic ramifications for the integrity and stability of the linear genome. In this Commentary, we attempt to define what is currently understood by the term ;telomere protection'. Delineating the defining boundaries of chromosome-end protection is important now more than ever, as it is becoming increasingly evident that, although unwanted DNA repair at telomeres must be avoided at all costs, the molecular players involved in recognition, signaling and repair of DNA damage might also serve to protect telomeres.
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Affiliation(s)
- Liana Oganesian
- The Salk Institute for Biological Studies, Molecular and Cellular Biology Department, La Jolla, CA 92037, USA
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35
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Cassar L, Li H, Jiang FX, Liu JP. TGF-beta induces telomerase-dependent pancreatic tumor cell cycle arrest. Mol Cell Endocrinol 2010; 320:97-105. [PMID: 20138964 DOI: 10.1016/j.mce.2010.02.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2009] [Revised: 01/27/2010] [Accepted: 02/02/2010] [Indexed: 12/21/2022]
Abstract
Recent studies suggest that transforming growth factor beta (TGF-beta) inhibits telomerase activity by repression of the telomerase reverse transcriptase (TERT) gene. In this report, we show that TGF-beta induces TERT repression-dependent apoptosis in pancreatic tumor, vascular smooth muscle, and cervical cancer cell cultures. TGF-beta activates Smad3 signaling, induces TERT gene repression and results in G1/S phase cell cycle arrest and apoptosis. TERT over-expression stimulates the G1/S phase transition and alienates TGF-beta-induced cell cycle arrest and apoptosis. Our data suggest that telomere maintenance is a limiting factor of the transition of the cell cycle. TGF-beta triggers cell cycle arrest and death by a mechanism involving telomerase deregulation of telomere maintenance.
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Affiliation(s)
- Lucy Cassar
- Department of Immunology, Monash University, Central Clinical School, AMREP, Commercial Road, Melbourne, Victoria 3004, Australia.
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36
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Zeng Z, Wang W, Yang Y, Chen Y, Yang X, Diehl JA, Liu X, Lei M. Structural basis of selective ubiquitination of TRF1 by SCFFbx4. Dev Cell 2010; 18:214-25. [PMID: 20159592 DOI: 10.1016/j.devcel.2010.01.007] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2009] [Revised: 12/12/2009] [Accepted: 01/05/2010] [Indexed: 12/15/2022]
Abstract
TRF1 is a critical regulator of telomere length. As such, TRF1 levels are regulated by ubiquitin-dependent proteolysis via an SCF E3 ligase where Fbx4 contributes to substrate specification. Here, we report the crystal structure of the Fbx4-TRF1 complex at 2.4 A resolution. Fbx4 contains an unusual substrate-binding domain that adopts a small GTPase fold. Strikingly, this atypical GTPase domain of Fbx4 binds to a globular domain of TRF1 through an intermolecular beta sheet, instead of recognizing short peptides/degrons as often seen in other F-box protein-substrate complexes. Importantly, mutations in this interface abrogate Fbx4-dependent TRF1 binding and ubiquitination. Furthermore, the data demonstrate that recognition of TRF1 by SCF(Fbx4) is regulated by another telomere protein, TIN2. Our results reveal an atypical small GTPase domain within Fbx4 as a substrate-binding motif for SCF(Fbx4) and uncover a mechanism for selective ubiquitination and degradation of TRF1 in telomere homeostasis control.
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Affiliation(s)
- Zhixiong Zeng
- Howard Hughes Medical Institute, University of Michigan Medical School, 1150 West Medical Center Drive, Ann Arbor, MI 48109, USA
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37
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Zhou WJ, Deng R, Zhang XY, Feng GK, Gu LQ, Zhu XF. G-quadruplex ligand SYUIQ-5 induces autophagy by telomere damage and TRF2 delocalization in cancer cells. Mol Cancer Ther 2010; 8:3203-13. [PMID: 19996277 DOI: 10.1158/1535-7163.mct-09-0244] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Agents stabilizing G-quadruplexes have the potential to destroy the functional structure of telomere and could therefore act as antitumor agents. We previously reported that SYUIQ-5 could stabilize G-quadruplex, induce senescence, and inhibit c-myc gene promoter activity. In this study, we showed that SYUIQ-5 inhibited proliferation of CNE2 and HeLa cancer cells, triggered a rapid and potent telomere DNA damage response characterized by the formation of telomeric foci gamma-H2AX, and obviously induced autophagy with the features of increased LC3-II and a punctuated pattern of YFP-LC3 fluorescence. These phenomena may primarily depend on the delocalization of TRF2 from telomere, which was further degraded by proteasomes. Furthermore, overexpression of TRF2 inhibited SYUIQ-5-induced gamma-H2AX expression. Also, ATM was activated following SYUIQ-5 treatment. The pretreatment with ATM inhibitor ku55933 and ATM siRNA effectively reduced the production of gamma-H2AX and LC3-II. ATM knockdown partially antagonized the anticancer effects of SYUIQ-5. Moreover, inhibition of autophagy by short hairpin RNA against the autophagy-related gene ATG5 attenuated the cytotoxicity of SYUIQ-5. These results indicated that SYUIQ-5 triggered potent telomere damage through TRF2 delocalization from telomeres, and eventually induced autophagic cell death in cancer cells. Our findings exhibit a novel mechanism that is responsible for the antitumor effects of SYUIQ-5.
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Affiliation(s)
- Wen-Jun Zhou
- State Key Laboratory of Oncology in South China, Cancer Center, Sun Yat-sen University, 651 Dongfeng Road East, Guangzhou 510060, China
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38
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Kim SH, Richardson M, Chinnakannu K, Bai VU, Menon M, Barrack ER, Reddy GPV. Androgen receptor interacts with telomeric proteins in prostate cancer cells. J Biol Chem 2010; 285:10472-6. [PMID: 20110352 DOI: 10.1074/jbc.m109.098798] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The telomeric complex, shelterin, plays a critical role in protecting chromosome ends from erosion, and disruption of these complexes can lead to chromosomal instability culminating in cell death or malignant transformation. We reported previously that dominant-negative mutants of one of the telomeric proteins called TIN2 cause death of androgen receptor (AR)-negative but not AR-positive prostate cancer cells, raising the question of a possible role of AR in the structural stability of telomeric complexes. Consistent with this possibility, in the present study, we observed that the AR antagonist Casodex (bicalutamide) disrupted telomeric complexes in AR-positive LNCaP cells but not in AR-negative PC-3 cells. Immunofluorescent studies revealed colocalization of TIN2 and AR. Reciprocal immunoprecipitation studies showed association of AR with telomeric proteins. Furthermore, telomeric proteins were overexpressed in prostate cancer cells compared with normal prostate epithelial cells, and sucrose density gradient analysis showed co-sedimentation of AR with telomeric proteins in a shelterin-like mega complex. Together, these observations suggest an allosteric role of AR in telomere complex stability in prostate cancer cells and suggest that AR-antagonist Casodex-mediated cell death may be due to telomere complex disruption.
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Affiliation(s)
- Sahn-Ho Kim
- Vattikuti Urology Institute, Henry Ford Hospital, Detroit, Michigan 48202, USA.
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Linger BR, Price CM. Conservation of telomere protein complexes: shuffling through evolution. Crit Rev Biochem Mol Biol 2009; 44:434-46. [PMID: 19839711 DOI: 10.3109/10409230903307329] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The rapid evolution of telomere proteins has hindered identification of orthologs from diverse species and created the impression that certain groups of eukaryotes have largely non-overlapping sets of telomere proteins. However, the recent identification of additional telomere proteins from various model organisms has dispelled this notion by expanding our understanding of the composition, architecture and range of telomere protein complexes present in individual species. It is now apparent that versions of the budding yeast CST complex and mammalian shelterin are present in multiple phyla. While the precise subunit composition and architecture of these complexes vary between species, the general function is often conserved. Despite the overall conservation of telomere protein complexes, there is still considerable species-specific variation, with some organisms having lost a particular subunit or even an entire complex. In some cases, complex components appear to have migrated between the telomere and the telomerase RNP. Finally, gene duplication has created telomere protein paralogs with novel functions. While one paralog may be part of a conserved telomere protein complex and have the expected function, the other paralog may serve in a completely different aspect of telomere biology.
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Affiliation(s)
- Benjamin R Linger
- Department of Cancer and Cell Biology, University of Cincinnati, Cincinnati, OH 45267-0521, USA
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40
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Sarthy J, Bae NS, Scrafford J, Baumann P. Human RAP1 inhibits non-homologous end joining at telomeres. EMBO J 2009; 28:3390-9. [PMID: 19763083 DOI: 10.1038/emboj.2009.275] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2009] [Accepted: 08/25/2009] [Indexed: 12/22/2022] Open
Abstract
Telomeres, the nucleoprotein structures at the ends of linear chromosomes, promote genome stability by distinguishing chromosome termini from DNA double-strand breaks (DSBs). Cells possess two principal pathways for DSB repair: homologous recombination and non-homologous end joining (NHEJ). Several studies have implicated TRF2 in the protection of telomeres from NHEJ, but the underlying mechanism remains poorly understood. Here, we show that TRF2 inhibits NHEJ, in part, by recruiting human RAP1 to telomeres. Heterologous targeting of hRAP1 to telomeric DNA was sufficient to bypass the need for TRF2 in protecting telomeric DNA from NHEJ in vitro. On expanding these studies in cells, we find that recruitment of hRAP1 to telomeres prevents chromosome fusions caused by the loss of TRF2/hRAP1 from chromosome ends despite activation of a DNA damage response. These results provide the first evidence that hRAP1 inhibits NHEJ at mammalian telomeres and identify hRAP1 as a mediator of genome stability.
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Affiliation(s)
- Jay Sarthy
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
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41
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A versatile viral system for expression and depletion of proteins in mammalian cells. PLoS One 2009; 4:e6529. [PMID: 19657394 PMCID: PMC2717805 DOI: 10.1371/journal.pone.0006529] [Citation(s) in RCA: 752] [Impact Index Per Article: 47.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2009] [Accepted: 07/08/2009] [Indexed: 12/12/2022] Open
Abstract
The ability to express or deplete proteins in living cells is crucial for the study of biological processes. Viral vectors are often useful to deliver DNA constructs to cells that are difficult to transfect by other methods. Lentiviruses have the additional advantage of being able to integrate into the genomes of non-dividing mammalian cells. However, existing viral expression systems generally require different vector backbones for expression of cDNA, small hairpin RNA (shRNA) or microRNA (miRNA) and provide limited drug selection markers. Furthermore, viral backbones are often recombinogenic in bacteria, complicating the generation and maintenance of desired clones. Here, we describe a collection of 59 vectors that comprise an integrated system for constitutive or inducible expression of cDNAs, shRNAs or miRNAs, and use a wide variety of drug selection markers. These vectors are based on the Gateway technology (Invitrogen) whereby the cDNA, shRNA or miRNA of interest is cloned into an Entry vector and then recombined into a Destination vector that carries the chosen viral backbone and drug selection marker. This recombination reaction generates the desired product with >95% efficiency and greatly reduces the frequency of unwanted recombination in bacteria. We generated Destination vectors for the production of both retroviruses and lentiviruses. Further, we characterized each vector for its viral titer production as well as its efficiency in expressing or depleting proteins of interest. We also generated multiple types of vectors for the production of fusion proteins and confirmed expression of each. We demonstrated the utility of these vectors in a variety of functional studies. First, we show that the FKBP12 Destabilization Domain system can be used to either express or deplete the protein of interest in mitotically-arrested cells. Also, we generate primary fibroblasts that can be induced to senesce in the presence or absence of DNA damage. Finally, we determined that both isoforms of the AT-Rich Interacting Domain 4B (ARID4B) protein could induce G1 arrest when overexpressed. As new technologies emerge, the vectors in this collection can be easily modified and adapted without the need for extensive recloning.
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Zhu Q, Meng L, Hsu JK, Lin T, Teishima J, Tsai RYL. GNL3L stabilizes the TRF1 complex and promotes mitotic transition. ACTA ACUST UNITED AC 2009; 185:827-39. [PMID: 19487455 PMCID: PMC2711588 DOI: 10.1083/jcb.200812121] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Telomeric repeat binding factor 1 (TRF1) is a component of the multiprotein complex "shelterin," which organizes the telomere into a high-order structure. TRF1 knockout embryos suffer from severe growth defects without apparent telomere dysfunction, suggesting an obligatory role for TRF1 in cell cycle control. To date, the mechanism regulating the mitotic increase in TRF1 protein expression and its function in mitosis remains unclear. Here, we identify guanine nucleotide-binding protein-like 3 (GNL3L), a GTP-binding protein most similar to nucleostemin, as a novel TRF1-interacting protein in vivo. GNL3L binds TRF1 in the nucleoplasm and is capable of promoting the homodimerization and telomeric association of TRF1, preventing promyelocytic leukemia body recruitment of telomere-bound TRF1, and stabilizing TRF1 protein by inhibiting its ubiquitylation and binding to FBX4, an E3 ubiquitin ligase for TRF1. Most importantly, the TRF1 protein-stabilizing activity of GNL3L mediates the mitotic increase of TRF1 protein and promotes the metaphase-to-anaphase transition. This work reveals novel aspects of TRF1 modulation by GNL3L.
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Affiliation(s)
- Qubo Zhu
- Center for Cancer and Stem Cell Biology, Alkek Institute of Biosciences and Technology, Texas A&M University System Health Science Center, Houston, TX 77030, USA
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Telomere and telomerase as targets for cancer therapy. Appl Biochem Biotechnol 2009; 160:1460-72. [PMID: 19412578 DOI: 10.1007/s12010-009-8633-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2009] [Accepted: 03/31/2009] [Indexed: 02/08/2023]
Abstract
Telomere maintenance and telomerase reactivation is essential for the transformation of most human cancer cells. Telomere shortening to the threshold length, mutations of the telomere-associated proteins, and/or telomerase RNA lead to telomeric dysfunction and therefore genomic instability. Telomerase up-regulation in 85% of human cancer cells has become a hallmark of cancers, hence a promising target for anticancer therapy. In this review, we discuss the mechanism of cancer due to telomere dysfunction and the resulting biological effects, the control of telomerase activity, and the new developments in cancer therapies targeting telomere and telomerase.
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Kaminker PG, Kim SH, Desprez PY, Campisi J. A novel form of the telomere-associated protein TIN2 localizes to the nuclear matrix. Cell Cycle 2009; 8:931-9. [PMID: 19229133 PMCID: PMC2751576 DOI: 10.4161/cc.8.6.7941] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Telomeres are specialized heterochromatin at the ends of linear chromosomes. Telomeres are crucial for maintaining genome stability and play important roles in cellular senescence and tumor biology. Six core proteins-TRF1, TRF2, TIN2, POT1, TPP1 and Rap1 (termed the telosome or shelterin complex)-regulate telomere structure and function. One of these proteins, TIN2, regulates telomere length and structure indirectly by interacting with TRF1, TRF2 and TPP1, but no direct function has been attributed to TIN2. Here we present evidence for a TIN2 isoform (TIN2L) that differs from the originally described TIN2 isoform (TIN2S) in two ways: TIN2L contains an additional 97 amino acids, and TIN2L associates strongly with the nuclear matrix. Stringent salt and detergent conditions failed to extract TIN2L from the nuclear matrix, despite removing other telomere components, including TIN2S. In human mammary epithelial cells, each isoform showed a distinct nuclear distribution both as a function of cell cycle position and telomere length. Our results suggest a dual role for TIN2 in mediating the function of the shelterin complex and tethering telomeres to the nuclear matrix.
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Affiliation(s)
- Patrick G. Kaminker
- Buck Institute for Age Research; Novato, California USA
- Life Sciences Division; Lawrence Berkeley National Laboratory; Berkeley, California USA
| | - Sahn-Ho Kim
- Life Sciences Division; Lawrence Berkeley National Laboratory; Berkeley, California USA
| | - Pierre-Yves Desprez
- Buck Institute for Age Research; Novato, California USA
- California Pacific Medical Center; Cancer Research Institute; San Francisco, California USA
| | - Judith Campisi
- Buck Institute for Age Research; Novato, California USA
- Life Sciences Division; Lawrence Berkeley National Laboratory; Berkeley, California USA
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Abstract
The mammalian protein POT1 binds to telomeric single-stranded DNA (ssDNA), protecting chromosome ends from being detected as sites of DNA damage. POT1 is composed of an N-terminal ssDNA-binding domain and a C-terminal protein interaction domain. With regard to the latter, POT1 heterodimerizes with the protein TPP1 to foster binding to telomeric ssDNA in vitro and binds the telomeric double-stranded-DNA-binding protein TRF2. We sought to determine which of these functions-ssDNA, TPP1, or TRF2 binding-was required to protect chromosome ends from being detected as DNA damage. Using separation-of-function POT1 mutants deficient in one of these three activities, we found that binding to TRF2 is dispensable for protecting telomeres but fosters robust loading of POT1 onto telomeric chromatin. Furthermore, we found that the telomeric ssDNA-binding activity and binding to TPP1 are required in cis for POT1 to protect telomeres. Mechanistically, binding of POT1 to telomeric ssDNA and association with TPP1 inhibit the localization of RPA, which can function as a DNA damage sensor, to telomeres.
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46
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Leslie M. Tag team at the telomeres. J Biophys Biochem Cytol 2008. [PMCID: PMC2364686 DOI: 10.1083/jcb.1813iti4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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