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Pangrácová M, Křivánek J, Vrchotová M, Sehadová H, Hadravová R, Hanus R, Lukšan O. Extended longevity of termite kings and queens is accompanied by extranuclear localization of telomerase in somatic organs and caste-specific expression of its isoforms. INSECT SCIENCE 2025; 32:364-384. [PMID: 39034424 PMCID: PMC11976694 DOI: 10.1111/1744-7917.13418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2024] [Revised: 06/03/2024] [Accepted: 06/04/2024] [Indexed: 07/23/2024]
Abstract
Kings and queens of termites are endowed with an extraordinary longevity coupled with lifelong fecundity. We recently reported that termite kings and queens display a dramatically increased enzymatic activity and abundance of telomerase in their somatic organs when compared to short-lived workers and soldiers. We hypothesized that this telomerase activation may represent a noncanonical pro-longevity function, independent of its canonical role in telomere maintenance. Here, we explore this avenue and investigate whether the presumed noncanonical role of telomerase may be due to alternative splicing of the catalytic telomerase subunit TERT and whether the subcellular localization of TERT isoforms differs among organs and castes in the termite Prorhinotermes simplex. We empirically confirm the expression of four in silico predicted splice variants (psTERT1-A, psTERT1-B, psTERT2-A, psTERT2-B), defined by N-terminal splicing implicating differential localizations, and C-terminal splicing giving rise to full-length and truncated isoforms. We show that the transcript proportions of the psTERT are caste- and tissue-specific and that the extranuclear full-length isoform TERT1-A is relatively enriched in the soma of neotenic kings and queens compared to their gonads and to the soma of workers. We also show that extranuclear TERT protein quantities are significantly higher in the soma of kings and queens compared to workers, namely due to the cytosolic TERT. Independently, we confirm by microscopy the extranuclear TERT localization in somatic organs. We conclude that the presumed pleiotropic action of telomerase combining the canonical nuclear role in telomere maintenance with extranuclear functions is driven by complex TERT splicing.
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Affiliation(s)
- Marie Pangrácová
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of SciencesPragueCzech Republic
- Faculty of ScienceCharles UniversityPragueCzech Republic
| | - Jan Křivánek
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of SciencesPragueCzech Republic
| | - Markéta Vrchotová
- Institute of EntomologyBiology Centre of the Czech Academy of SciencesČeské BudějoviceCzech Republic
- Faculty of ScienceUniversity of South BohemiaČeské BudějoviceCzech Republic
| | - Hana Sehadová
- Institute of EntomologyBiology Centre of the Czech Academy of SciencesČeské BudějoviceCzech Republic
- Faculty of ScienceUniversity of South BohemiaČeské BudějoviceCzech Republic
| | - Romana Hadravová
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of SciencesPragueCzech Republic
| | - Robert Hanus
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of SciencesPragueCzech Republic
| | - Ondřej Lukšan
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of SciencesPragueCzech Republic
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Kim JJ, Ahn A, Ying JY, Ludlow AT. Discovery and characterization of a novel telomerase alternative splicing isoform that protects lung cancer cells from chemotherapy induced cell death. Sci Rep 2025; 15:6787. [PMID: 40000722 PMCID: PMC11861669 DOI: 10.1038/s41598-025-90639-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2024] [Accepted: 02/14/2025] [Indexed: 02/27/2025] Open
Abstract
All cancer cells must adopt a telomere maintenance mechanism to achieve replicative immortality. Most human cancer cells utilize the enzyme telomerase to maintain telomeres. Alternative splicing of TERT regulates the amount and function of telomerase, however many alternative splicing isoforms of TERT have unknown functions. Single molecule long read RNA/cDNA sequencing of TERT revealed 45 TERT mRNA variants including 13 known and 32 novel variants. Among the variants, TERT Delta 2-4, which lacks exons 2-4 but retains the original open reading frame, was selected for further study. Induced pluripotent stem cells and cancer cells express higher levels of TERT Delta 2-4 compared to primary human bronchial epithelial cells. Overexpression of TERT Delta 2-4 enhanced clonogenicity and resistance to cisplatin-induced cell death. Knockdown of endogenous TERT Delta 2-4 in Calu-6 cells reduced clonogenicity and resistance to cisplatin. Our results suggest that TERT Delta 2-4 enhances cancer cells' resistance to cell death. RNA sequencing following knockdown of Delta 2-4 TERT indicates that translation is downregulated and that mitochondrial related proteins are upregulated compared to controls. Overall, our data indicate that TERT produces many isoforms that influence the function of TERT and the abundance and activity of telomerase.
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Affiliation(s)
- Jeongjin J Kim
- School of Kinesiology, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Alexander Ahn
- School of Kinesiology, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Jeffrey Y Ying
- School of Kinesiology, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Andrew T Ludlow
- School of Kinesiology, University of Michigan, Ann Arbor, MI, 48109, USA.
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Huang S, Lau CH, Tin C, Lam RHW. Extended replicative lifespan of primary resting T cells by CRISPR/dCas9-based epigenetic modifiers and transcriptional activators. Cell Mol Life Sci 2024; 81:407. [PMID: 39287670 PMCID: PMC11408452 DOI: 10.1007/s00018-024-05415-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Revised: 07/24/2024] [Accepted: 08/16/2024] [Indexed: 09/19/2024]
Abstract
Extension of the replicative lifespan of primary cells can be achieved by activating human telomerase reverse transcriptase (hTERT) to maintain sufficient telomere lengths. In this work, we utilize CRISPR/dCas9-based epigenetic modifiers (p300 histone acetyltransferase and TET1 DNA demethylase) and transcriptional activators (VPH and VPR) to reactivate the endogenous TERT gene in unstimulated T cells in the peripheral blood mononuclear cells (PBMCs) by rewiring the epigenetic marks of the TERT promoter. Importantly, we have successfully expanded resting T cells and delayed their cellular senescence for at least three months through TERT reactivation, without affecting the expression of a T-cell marker (CD3) or inducing an accelerated cell division rate. We have also demonstrated the effectiveness of these CRISPR tools in HEK293FT and THP-1-derived macrophages. TERT reactivation and replicative senescence delay were achieved without inducing malignancy transformation, as shown in various cellular senescence assays, cell cycle state, proliferation rate, cell viability, and karyotype analyses. Our chromatin immunoprecipitation (ChIP)-qPCR data together with TERT mRNA and protein expression analyses confirmed the specificity of CRISPR-based transcription activators in modulating epigenetic marks of the TERT promoter, and induced telomerase expression. Therefore, the strategy of cell immortalization described here can be potentially adopted and generalized to delay cell death or even immortalize any other cell types.
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Affiliation(s)
- Siping Huang
- Department of Biomedical Engineering, City University of Hong Kong, P6414, Yeung Kin Man Academic Building, 83 Tat Chee Avenue, Kowloon Tong, Hong Kong, SAR, China
| | - Cia-Hin Lau
- Department of Biomedical Engineering, City University of Hong Kong, P6414, Yeung Kin Man Academic Building, 83 Tat Chee Avenue, Kowloon Tong, Hong Kong, SAR, China
| | - Chung Tin
- Department of Biomedical Engineering, City University of Hong Kong, P6414, Yeung Kin Man Academic Building, 83 Tat Chee Avenue, Kowloon Tong, Hong Kong, SAR, China.
| | - Raymond H W Lam
- Department of Biomedical Engineering, City University of Hong Kong, P6414, Yeung Kin Man Academic Building, 83 Tat Chee Avenue, Kowloon Tong, Hong Kong, SAR, China.
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Sugiyama Y, Okada S, Daigaku Y, Kusumoto E, Ito T. Strategic targeting of Cas9 nickase induces large segmental duplications. CELL GENOMICS 2024; 4:100610. [PMID: 39053455 PMCID: PMC11406185 DOI: 10.1016/j.xgen.2024.100610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 04/15/2024] [Accepted: 07/02/2024] [Indexed: 07/27/2024]
Abstract
Gene/segmental duplications play crucial roles in genome evolution and variation. Here, we introduce paired nicking-induced amplification (PNAmp) for their experimental induction. PNAmp strategically places two Cas9 nickases upstream and downstream of a replication origin on opposite strands. This configuration directs the sister replication forks initiated from the origin to break at the nicks, generating a pair of one-ended double-strand breaks. If homologous sequences flank the two break sites, then end resection converts them to single-stranded DNAs that readily anneal to drive duplication of the region bounded by the homologous sequences. PNAmp induces duplication of segments as large as ∼1 Mb with efficiencies exceeding 10% in the budding yeast Saccharomyces cerevisiae. Furthermore, appropriate splint DNAs allow PNAmp to duplicate/multiplicate even segments not bounded by homologous sequences. We also provide evidence for PNAmp in mammalian cells. Therefore, PNAmp provides a prototype method to induce structural variations by manipulating replication fork progression.
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Affiliation(s)
- Yuki Sugiyama
- Department of Biochemistry, Kyushu University Graduate School of Medical Sciences, Fukuoka 812-8582, Japan
| | - Satoshi Okada
- Department of Biochemistry, Kyushu University Graduate School of Medical Sciences, Fukuoka 812-8582, Japan
| | - Yasukazu Daigaku
- Cancer Genome Dynamics Project, Cancer Institute, Japanese Foundation for Cancer Research, Tokyo 135-8550, Japan
| | - Emiko Kusumoto
- Department of Biochemistry, Kyushu University Graduate School of Medical Sciences, Fukuoka 812-8582, Japan
| | - Takashi Ito
- Department of Biochemistry, Kyushu University Graduate School of Medical Sciences, Fukuoka 812-8582, Japan.
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Huang J, Feng Y, Shi Y, Shao W, Li G, Chen G, Li Y, Yang Z, Yao Z. Telomeres and telomerase in Sarcoma disease and therapy. Int J Med Sci 2024; 21:2065-2080. [PMID: 39239547 PMCID: PMC11373546 DOI: 10.7150/ijms.97485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2024] [Accepted: 07/24/2024] [Indexed: 09/07/2024] Open
Abstract
Sarcoma is a rare tumor derived from the mesenchymal tissue and mainly found in children and adolescents. The outcome for patients with sarcoma is relatively poor compared with that for many other solid malignant tumors. Sarcomas have a highly heterogeneous pathogenesis, histopathology and biological behavior. Dysregulated signaling pathways and various gene mutations are frequently observed in sarcomas. The telomere maintenance mechanism (TMM) has recently been considered as a prognostic factor for patients with sarcomas, and alternative lengthening of telomeres (ALT) positivity has been correlated with poor outcomes in patients with several types of sarcomas. Therefore, telomeres and telomerases may be useful targets for treating sarcomas. This review aims to provide an overview of telomere and telomerase biology in sarcomas.
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Affiliation(s)
- Jin Huang
- Department of Cancer Research Institute, The Third Affiliated Hospital of Kunming Medical University (Yunnan Cancer Hospital, Yunnan Cancer Center), Kunming, Yunnan, 650118, China
- Bone and Soft Tissue Tumours Research Centre of Yunnan Province, Department of Orthopaedics, The Third Affiliated Hospital of Kunming Medical University (Yunnan Cancer Hospital, Yunnan Cancer Center), Kunming, Yunnan, 650118, China
| | - Yan Feng
- Department of Cancer Research Institute, The Third Affiliated Hospital of Kunming Medical University (Yunnan Cancer Hospital, Yunnan Cancer Center), Kunming, Yunnan, 650118, China
- Bone and Soft Tissue Tumours Research Centre of Yunnan Province, Department of Orthopaedics, The Third Affiliated Hospital of Kunming Medical University (Yunnan Cancer Hospital, Yunnan Cancer Center), Kunming, Yunnan, 650118, China
| | - YangJing Shi
- Kunming Medical University, Kunming, Yunnan, 650500, China
| | - Weilin Shao
- Department of Cancer Research Institute, The Third Affiliated Hospital of Kunming Medical University (Yunnan Cancer Hospital, Yunnan Cancer Center), Kunming, Yunnan, 650118, China
- Bone and Soft Tissue Tumours Research Centre of Yunnan Province, Department of Orthopaedics, The Third Affiliated Hospital of Kunming Medical University (Yunnan Cancer Hospital, Yunnan Cancer Center), Kunming, Yunnan, 650118, China
| | - Genshan Li
- Bone and Soft Tissue Tumours Research Centre of Yunnan Province, Department of Orthopaedics, The Third Affiliated Hospital of Kunming Medical University (Yunnan Cancer Hospital, Yunnan Cancer Center), Kunming, Yunnan, 650118, China
| | - Gangxian Chen
- Bone and Soft Tissue Tumours Research Centre of Yunnan Province, Department of Orthopaedics, The Third Affiliated Hospital of Kunming Medical University (Yunnan Cancer Hospital, Yunnan Cancer Center), Kunming, Yunnan, 650118, China
| | - Ying Li
- Bone and Soft Tissue Tumours Research Centre of Yunnan Province, Department of Orthopaedics, The Third Affiliated Hospital of Kunming Medical University (Yunnan Cancer Hospital, Yunnan Cancer Center), Kunming, Yunnan, 650118, China
| | - Zuozhang Yang
- Bone and Soft Tissue Tumours Research Centre of Yunnan Province, Department of Orthopaedics, The Third Affiliated Hospital of Kunming Medical University (Yunnan Cancer Hospital, Yunnan Cancer Center), Kunming, Yunnan, 650118, China
| | - Zhihong Yao
- Department of Cancer Research Institute, The Third Affiliated Hospital of Kunming Medical University (Yunnan Cancer Hospital, Yunnan Cancer Center), Kunming, Yunnan, 650118, China
- Bone and Soft Tissue Tumours Research Centre of Yunnan Province, Department of Orthopaedics, The Third Affiliated Hospital of Kunming Medical University (Yunnan Cancer Hospital, Yunnan Cancer Center), Kunming, Yunnan, 650118, China
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Guan L, Viswanathan V, Jiang Y, Vijayakumar S, Cao H, Zhao J, Colburg DRC, Neuhöfer P, Zhang Y, Wang J, Xu Y, Laseinde EE, Hildebrand R, Rahman M, Frock R, Kong C, Beachy PA, Artandi S, Le QT. Tert-expressing cells contribute to salivary gland homeostasis and tissue regeneration after radiation therapy. Genes Dev 2024; 38:569-582. [PMID: 38997156 PMCID: PMC11293384 DOI: 10.1101/gad.351577.124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Accepted: 06/25/2024] [Indexed: 07/14/2024]
Abstract
Salivary gland homeostasis and regeneration after radiotherapy depend significantly on progenitor cells. However, the lineage of submandibular gland (SMG) progenitor cells remains less defined compared with other normal organs. Here, using a mouse strain expressing regulated CreERT2 recombinase from the endogenous Tert locus, we identify a distinct telomerase-expressing (TertHigh) cell population located in the ductal region of the adult SMG. These TertHigh cells contribute to ductal cell generation during SMG homeostasis and to both ductal and acinar cell renewal 1 year after radiotherapy. TertHigh cells maintain self-renewal capacity during in vitro culture, exhibit resistance to radiation damage, and demonstrate enhanced proliferative activity after radiation exposure. Similarly, primary human SMG cells with high Tert expression display enhanced cell survival after radiotherapy, and CRISPR-activated Tert in human SMG spheres increases proliferation after radiation. RNA sequencing reveals upregulation of "cell cycling" and "oxidative stress response" pathways in TertHigh cells following radiation. Mechanistically, Tert appears to modulate cell survival through ROS levels in SMG spheres following radiation damage. Our findings highlight the significance of TertHigh cells in salivary gland biology, providing insights into their response to radiotherapy and into their use as a potential target for enhancing salivary gland regeneration after radiotherapy.
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Affiliation(s)
- Li Guan
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Vignesh Viswanathan
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Yuyan Jiang
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Sivakamasundari Vijayakumar
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Hongbin Cao
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Junfei Zhao
- Department of Pathology and Cell Biology, Columbia University, New York, New York 10032, USA
| | | | - Patrick Neuhöfer
- Stanford Cancer Institute, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Yiru Zhang
- Department of Radiology, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
| | - Jinglong Wang
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Yu Xu
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Eyiwunmi E Laseinde
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Rachel Hildebrand
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Mobeen Rahman
- Department of Pathology, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Richard Frock
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Christina Kong
- Department of Pathology, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Philip A Beachy
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Steven Artandi
- Stanford Cancer Institute, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Quynh-Thu Le
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California 94305, USA;
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Deb S, Berei J, Miliavski E, Khan MJ, Broder TJ, Akurugo TA, Lund C, Fleming SE, Hillwig R, Ross J, Puri N. The Effects of Smoking on Telomere Length, Induction of Oncogenic Stress, and Chronic Inflammatory Responses Leading to Aging. Cells 2024; 13:884. [PMID: 38891017 PMCID: PMC11172003 DOI: 10.3390/cells13110884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 05/11/2024] [Accepted: 05/18/2024] [Indexed: 06/20/2024] Open
Abstract
Telomeres, potential biomarkers of aging, are known to shorten with continued cigarette smoke exposure. In order to further investigate this process and its impact on cellular stress and inflammation, we used an in vitro model with cigarette smoke extract (CSE) and observed the downregulation of telomere stabilizing TRF2 and POT1 genes after CSE treatment. hTERT is a subunit of telomerase and a well-known oncogenic marker, which is overexpressed in over 85% of cancers and may contribute to lung cancer development in smokers. We also observed an increase in hTERT and ISG15 expression levels after CSE treatment, as well as increased protein levels revealed by immunohistochemical staining in smokers' lung tissue samples compared to non-smokers. The effects of ISG15 overexpression were further studied by quantifying IFN-γ, an inflammatory protein induced by ISG15, which showed greater upregulation in smokers compared to non-smokers. Similar changes in gene expression patterns for TRF2, POT1, hTERT, and ISG15 were observed in blood and buccal swab samples from smokers compared to non-smokers. The results from this study provide insight into the mechanisms behind smoking causing telomere shortening and how this may contribute to the induction of inflammation and/or tumorigenesis, which may lead to comorbidities in smokers.
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Affiliation(s)
- Shreya Deb
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, USA; (S.D.); (J.B.); (E.M.); (M.J.K.); (T.J.B.); (T.A.A.); (C.L.)
| | - Joseph Berei
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, USA; (S.D.); (J.B.); (E.M.); (M.J.K.); (T.J.B.); (T.A.A.); (C.L.)
| | - Edward Miliavski
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, USA; (S.D.); (J.B.); (E.M.); (M.J.K.); (T.J.B.); (T.A.A.); (C.L.)
| | - Muhammad J. Khan
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, USA; (S.D.); (J.B.); (E.M.); (M.J.K.); (T.J.B.); (T.A.A.); (C.L.)
| | - Taylor J. Broder
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, USA; (S.D.); (J.B.); (E.M.); (M.J.K.); (T.J.B.); (T.A.A.); (C.L.)
| | - Thomas A. Akurugo
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, USA; (S.D.); (J.B.); (E.M.); (M.J.K.); (T.J.B.); (T.A.A.); (C.L.)
| | - Cody Lund
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, USA; (S.D.); (J.B.); (E.M.); (M.J.K.); (T.J.B.); (T.A.A.); (C.L.)
| | - Sara E. Fleming
- Department of Pathology, UW Health SwedishAmerican Hospital, Rockford, IL 61107, USA;
| | - Robert Hillwig
- Department of Health Sciences Education, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, USA;
| | - Joseph Ross
- Department of Family and Community Medicine, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, USA;
| | - Neelu Puri
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, USA; (S.D.); (J.B.); (E.M.); (M.J.K.); (T.J.B.); (T.A.A.); (C.L.)
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Cui L, Zheng Y, Xu R, Lin Y, Zheng J, Lin P, Guo B, Sun S, Zhao X. Alternative pre-mRNA splicing in stem cell function and therapeutic potential: A critical review of current evidence. Int J Biol Macromol 2024; 268:131781. [PMID: 38657924 DOI: 10.1016/j.ijbiomac.2024.131781] [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: 02/28/2024] [Revised: 03/23/2024] [Accepted: 04/21/2024] [Indexed: 04/26/2024]
Abstract
Alternative splicing is a crucial regulator in stem cell biology, intricately influencing the functions of various biological macromolecules, particularly pre-mRNAs and the resultant protein isoforms. This regulatory mechanism is vital in determining stem cell pluripotency, differentiation, and proliferation. Alternative splicing's role in allowing single genes to produce multiple protein isoforms facilitates the proteomic diversity that is essential for stem cells' functional complexity. This review delves into the critical impact of alternative splicing on cellular functions, focusing on its interaction with key macromolecules and how this affects cellular behavior. We critically examine how alternative splicing modulates the function and stability of pre-mRNAs, leading to diverse protein expressions that govern stem cell characteristics, including pluripotency, self-renewal, survival, proliferation, differentiation, aging, migration, somatic reprogramming, and genomic stability. Furthermore, the review discusses the therapeutic potential of targeting alternative splicing-related pathways in disease treatment, particularly focusing on the modulation of RNA and protein interactions. We address the challenges and future prospects in this field, underscoring the need for further exploration to unravel the complex interplay between alternative splicing, RNA, proteins, and stem cell behaviors, which is crucial for advancing our understanding and therapeutic approaches in regenerative medicine and disease treatment.
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Affiliation(s)
- Li Cui
- Stomatological Hospital, School of Stomatology, Southern Medical University, Guangzhou, 510280, Guangdong, China.
| | - Yucheng Zheng
- Stomatological Hospital, School of Stomatology, Southern Medical University, Guangzhou, 510280, Guangdong, China
| | - Rongwei Xu
- Stomatological Hospital, School of Stomatology, Southern Medical University, Guangzhou, 510280, Guangdong, China; Hospital of Stomatology, Zunyi Medical University, Zunyi 563000, China
| | - Yunfan Lin
- Stomatological Hospital, School of Stomatology, Southern Medical University, Guangzhou, 510280, Guangdong, China
| | - Jiarong Zheng
- Department of Dentistry, the First Affiliated Hospital, Sun Yat-Sen University, Guangzhou 510080, China
| | - Pei Lin
- Stomatological Hospital, School of Stomatology, Southern Medical University, Guangzhou, 510280, Guangdong, China
| | - Bing Guo
- Department of Dentistry, the First Affiliated Hospital, Sun Yat-Sen University, Guangzhou 510080, China
| | - Shuyu Sun
- Stomatological Hospital, School of Stomatology, Southern Medical University, Guangzhou, 510280, Guangdong, China
| | - Xinyuan Zhao
- Stomatological Hospital, School of Stomatology, Southern Medical University, Guangzhou, 510280, Guangdong, China.
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9
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Mason CE, Sierra MA, Feng HJ, Bailey SM. Telomeres and aging: on and off the planet! Biogerontology 2024; 25:313-327. [PMID: 38581556 PMCID: PMC10998805 DOI: 10.1007/s10522-024-10098-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/13/2024] [Indexed: 04/08/2024]
Abstract
Improving human healthspan in our rapidly aging population has never been more imperative. Telomeres, protective "caps" at the ends of linear chromosomes, are essential for maintaining genome stability of eukaryotic genomes. Due to their physical location and the "end-replication problem" first envisioned by Dr. Alexey Olovnikov, telomeres shorten with cell division, the implications of which are remarkably profound. Telomeres are hallmarks and molecular drivers of aging, as well as fundamental integrating components of the cumulative effects of genetic, lifestyle, and environmental factors that erode telomere length over time. Ongoing telomere attrition and the resulting limit to replicative potential imposed by cellular senescence serves a powerful tumor suppressor function, and also underlies aging and a spectrum of age-related degenerative pathologies, including reduced fertility, dementias, cardiovascular disease and cancer. However, very little data exists regarding the extraordinary stressors and exposures associated with long-duration space exploration and eventual habitation of other planets, nor how such missions will influence telomeres, reproduction, health, disease risk, and aging. Here, we briefly review our current understanding, which has advanced significantly in recent years as a result of the NASA Twins Study, the most comprehensive evaluation of human health effects associated with spaceflight ever conducted. Thus, the Twins Study is at the forefront of personalized space medicine approaches for astronauts and sets the stage for subsequent missions. We also extrapolate from current understanding to future missions, highlighting potential biological and biochemical strategies that may enable human survival, and consider the prospect of longevity in the extreme environment of space.
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Affiliation(s)
- Christopher E Mason
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, USA
- The HRH Prince Alwaleed Bin Talal Bin Abdulaziz Alsaud Institute for Computational Biomedicine and WorldQuant Initiative for Quantitative Prediction, Weill Cornell Medicine, New York, NY, USA
| | - Maria A Sierra
- The HRH Prince Alwaleed Bin Talal Bin Abdulaziz Alsaud Institute for Computational Biomedicine and WorldQuant Initiative for Quantitative Prediction, Weill Cornell Medicine, New York, NY, USA
- Tri-Institutional Computational Biology & Medicine Program, Weill Cornell Medicine, New York, NY, USA
| | - Henry J Feng
- Department of Biological Sciences, Columbia University, New York, NY, USA
- Faculty of Medicine and Health, Sydney Medical School, University of Sydney, Sydney, Australia
| | - Susan M Bailey
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, USA.
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10
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Dunn PL, Logeswaran D, Chen JJL. Telomerase-Mediated Anti-Ageing Interventions. Subcell Biochem 2024; 107:1-20. [PMID: 39693017 DOI: 10.1007/978-3-031-66768-8_1] [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] [Indexed: 12/19/2024]
Abstract
The ageing process involves a gradual decline of chromosome integrity throughout an organism's lifespan. Telomeres are protective DNA-protein complexes that cap the ends of linear chromosomes in eukaryotic organisms. Telomeric DNA consists of long stretches of short "TTAGGG" repeats that are conserved across most eukaryotes including humans. Telomeres shorten progressively with each round of DNA replication due to the inability of conventional DNA polymerase to completely replicate the chromosome ends, known as the "end-replication problem". The telomerase enzyme counteracts the telomeric DNA loss by de novo addition of telomeric repeats onto chromosomal ends. Germline and stem cells maintain significant levels of telomerase activity to maintain telomere length and can divide almost indefinitely. However, the differentiation of stem cells accompanies the inactivation of telomerase gene expression, resulting in the progressive shortening of telomeres in somatic cells over successive divisions. Critically short telomeres elicit and sustain a persistent DNA damage response leading to permanent growth arrest of cells known as cellular senescence, a hallmark of cellular ageing. The accumulation of senescent cells in tissues and organs contributes to organismal ageing. Thus, the prevention of telomere shortening is a promising means to delay or even reverse cellular ageing. In this chapter, we summarize potential anti-ageing interventions that mitigate telomere shortening through increasing telomerase level or activity and discuss these strategies' risks, benefits, and future outlooks.
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Affiliation(s)
- Phoebe L Dunn
- School of Life Sciences, Arizona State University, Tempe, Arizona, USA
| | | | - Julian J-L Chen
- School of Molecular Sciences, Arizona State University, Tempe, Arizona, USA.
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11
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Kim JJ, Sayed ME, Ahn A, Slusher AL, Ying JY, Ludlow AT. Dynamics of TERT regulation via alternative splicing in stem cells and cancer cells. PLoS One 2023; 18:e0289327. [PMID: 37531400 PMCID: PMC10395990 DOI: 10.1371/journal.pone.0289327] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Accepted: 07/17/2023] [Indexed: 08/04/2023] Open
Abstract
Part of the regulation of telomerase activity includes the alternative splicing (AS) of the catalytic subunit telomerase reverse transcriptase (TERT). Although a therapeutic window for telomerase/TERT inhibition exists between cancer cells and somatic cells, stem cells express TERT and rely on telomerase activity for physiological replacement of cells. Therefore, identifying differences in TERT regulation between stem cells and cancer cells is essential for developing telomerase inhibition-based cancer therapies that reduce damage to stem cells. In this study, we measured TERT splice variant expression and telomerase activity in induced pluripotent stem cells (iPSCs), neural progenitor cells (NPCs), and non-small cell lung cancer cells (NSCLC, Calu-6 cells). We observed that a NOVA1-PTBP1-PTBP2 axis regulates TERT alternative splicing (AS) in iPSCs and their differentiation into NPCs. We also found that splice-switching of TERT, which regulates telomerase activity, is induced by different cell densities in stem cells but not cancer cells. Lastly, we identified cell type-specific splicing factors that regulate TERT AS. Overall, our findings represent an important step forward in understanding the regulation of TERT AS in stem cells and cancer cells.
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Affiliation(s)
- Jeongjin J. Kim
- School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Mohammed E. Sayed
- School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Alexander Ahn
- School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Aaron L. Slusher
- School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Jeffrey Y. Ying
- School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Andrew T. Ludlow
- School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States of America
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12
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Shao MM, Zhai K, Huang ZY, Yi FS, Zheng SC, Liu YL, Qiao X, Chen QY, Wang Z, Shi HZ. Characterization of the alternative splicing landscape in lung adenocarcinoma reveals novel prognosis signature associated with B cells. PLoS One 2023; 18:e0279018. [PMID: 37432957 DOI: 10.1371/journal.pone.0279018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Accepted: 11/07/2022] [Indexed: 07/13/2023] Open
Abstract
BACKGROUND Lung cancer is the second most commonly diagnosed cancer and the leading cause of cancer-related death. Malignant pleural effusion (MPE) is a special microenvironment for lung cancer metastasis. Alternative splicing, which is regulated by splicing factors, affects the expression of most genes and influences carcinogenesis and metastasis. METHODS mRNA-seq data and alternative splicing events in lung adenocarcinoma (LUAD) were obtained from The Cancer Genome Atlas (TCGA). A risk model was generated by Cox regression analyses and LASSO regression. Cell isolation and flow cytometry were used to identify B cells. RESULTS We systematically analyzed the splicing factors, alternative splicing events, clinical characteristics, and immunologic features of LUAD in the TCGA cohort. A risk signature based on 23 alternative splicing events was established and identified as an independent prognosis factor in LUAD. Among all patients, the risk signature showed a better prognostic value in metastatic patients. By single-sample gene set enrichment analysis, we found that among tumor-infiltrating lymphocytes, B cells were most significantly correlated to the risk score. Furthermore, we investigated the classification and function of B cells in MPE, a metastatic microenvironment of LUAD, and found that regulatory B cells might participate in the regulation of the immune microenvironment of MPE through antigen presentation and promotion of regulatory T cell differentiation. CONCLUSIONS We evaluated the prognostic value of alternative splicing events in LUAD and metastatic LUAD. We found that regulatory B cells had the function of antigen presentation, inhibited naïve T cells from differentiating into Th1 cells, and promoted Treg differentiation in LUAD patients with MPE.
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Affiliation(s)
- Ming-Ming Shao
- Department of Respiratory and Critical Care Medicine, Beijing Institute of Respiratory Medicine and Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China
| | - Kan Zhai
- Department of Respiratory and Critical Care Medicine, Beijing Institute of Respiratory Medicine and Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China
| | - Zhong-Yin Huang
- Department of Respiratory and Critical Care Medicine, Beijing Institute of Respiratory Medicine and Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China
| | - Feng-Shuang Yi
- Department of Respiratory and Critical Care Medicine, Beijing Institute of Respiratory Medicine and Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China
| | - Sheng-Cai Zheng
- Department of Respiratory and Critical Care Medicine, Beijing Institute of Respiratory Medicine and Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China
| | - Ya-Lan Liu
- Department of Respiratory and Critical Care Medicine, Beijing Institute of Respiratory Medicine and Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China
| | - Xin Qiao
- Department of Respiratory and Critical Care Medicine, Beijing Institute of Respiratory Medicine and Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China
| | - Qing-Yu Chen
- Department of Respiratory and Critical Care Medicine, Beijing Institute of Respiratory Medicine and Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China
| | - Zhen Wang
- Department of Respiratory and Critical Care Medicine, Beijing Institute of Respiratory Medicine and Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China
| | - Huan-Zhong Shi
- Department of Respiratory and Critical Care Medicine, Beijing Institute of Respiratory Medicine and Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China
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Marasco LE, Kornblihtt AR. The physiology of alternative splicing. Nat Rev Mol Cell Biol 2023; 24:242-254. [PMID: 36229538 DOI: 10.1038/s41580-022-00545-z] [Citation(s) in RCA: 209] [Impact Index Per Article: 104.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/15/2022] [Indexed: 11/09/2022]
Abstract
Alternative splicing is a substantial contributor to the high complexity of transcriptomes of multicellular eukaryotes. In this Review, we discuss the accumulated evidence that most of this complexity is reflected at the protein level and fundamentally shapes the physiology and pathology of organisms. This notion is supported not only by genome-wide analyses but, mainly, by detailed studies showing that global and gene-specific modulations of alternative splicing regulate highly diverse processes such as tissue-specific and species-specific cell differentiation, thermal regulation, neuron self-avoidance, infrared sensing, the Warburg effect, maintenance of telomere length, cancer and autism spectrum disorders (ASD). We also discuss how mastering the control of alternative splicing paved the way to clinically approved therapies for hereditary diseases.
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Affiliation(s)
- Luciano E Marasco
- Universidad de Buenos Aires (UBA), Facultad de Ciencias Exactas y Naturales, Departamento de Fisiología, Biología Moleculary Celular and CONICET-UBA, Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), Buenos Aires, Argentina
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Alberto R Kornblihtt
- Universidad de Buenos Aires (UBA), Facultad de Ciencias Exactas y Naturales, Departamento de Fisiología, Biología Moleculary Celular and CONICET-UBA, Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), Buenos Aires, Argentina.
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14
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Shepelev N, Dontsova O, Rubtsova M. Post-Transcriptional and Post-Translational Modifications in Telomerase Biogenesis and Recruitment to Telomeres. Int J Mol Sci 2023; 24:5027. [PMID: 36902458 PMCID: PMC10003056 DOI: 10.3390/ijms24055027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 03/02/2023] [Accepted: 03/03/2023] [Indexed: 03/08/2023] Open
Abstract
Telomere length is associated with the proliferative potential of cells. Telomerase is an enzyme that elongates telomeres throughout the entire lifespan of an organism in stem cells, germ cells, and cells of constantly renewed tissues. It is activated during cellular division, including regeneration and immune responses. The biogenesis of telomerase components and their assembly and functional localization to the telomere is a complex system regulated at multiple levels, where each step must be tuned to the cellular requirements. Any defect in the function or localization of the components of the telomerase biogenesis and functional system will affect the maintenance of telomere length, which is critical to the processes of regeneration, immune response, embryonic development, and cancer progression. An understanding of the regulatory mechanisms of telomerase biogenesis and activity is necessary for the development of approaches toward manipulating telomerase to influence these processes. The present review focuses on the molecular mechanisms involved in the major steps of telomerase regulation and the role of post-transcriptional and post-translational modifications in telomerase biogenesis and function in yeast and vertebrates.
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Affiliation(s)
- Nikita Shepelev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117437, Russia
- Chemistry Department and Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119234, Russia
- Skolkovo Institute of Science and Technology, Moscow 121205, Russia
| | - Olga Dontsova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117437, Russia
- Chemistry Department and Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119234, Russia
- Skolkovo Institute of Science and Technology, Moscow 121205, Russia
| | - Maria Rubtsova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117437, Russia
- Chemistry Department and Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119234, Russia
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15
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Revy P, Kannengiesser C, Bertuch AA. Genetics of human telomere biology disorders. Nat Rev Genet 2023; 24:86-108. [PMID: 36151328 DOI: 10.1038/s41576-022-00527-z] [Citation(s) in RCA: 68] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/11/2022] [Indexed: 01/24/2023]
Abstract
Telomeres are specialized nucleoprotein structures at the ends of linear chromosomes that prevent the activation of DNA damage response and repair pathways. Numerous factors localize at telomeres to regulate their length, structure and function, to avert replicative senescence or genome instability and cell death. In humans, Mendelian defects in several of these factors can result in abnormally short or dysfunctional telomeres, causing a group of rare heterogeneous premature-ageing diseases, termed telomeropathies, short-telomere syndromes or telomere biology disorders (TBDs). Here, we review the TBD-causing genes identified so far and describe their main functions associated with telomere biology. We present molecular aspects of TBDs, including genetic anticipation, phenocopy, incomplete penetrance and somatic genetic rescue, which underlie the complexity of these diseases. We also discuss the implications of phenotypic and genetic features of TBDs on fundamental aspects related to human telomere biology, ageing and cancer, as well as on diagnostic, therapeutic and clinical approaches.
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Affiliation(s)
- Patrick Revy
- INSERM UMR 1163, Laboratory of Genome Dynamics in the Immune System, Equipe Labellisée Ligue Nationale contre le Cancer, Paris, France.
- Université Paris Cité, Imagine Institute, Paris, France.
| | - Caroline Kannengiesser
- APHP Service de Génétique, Hôpital Bichat, Paris, France
- Inserm U1152, Université Paris Cité, Paris, France
| | - Alison A Bertuch
- Departments of Paediatrics and Molecular & Human Genetics, Baylor College of Medicine, Houston, TX, USA
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16
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Liu T, Li S, Xia C, Xu D. TERT promoter mutations and methylation for telomerase activation in urothelial carcinomas: New mechanistic insights and clinical significance. Front Immunol 2023; 13:1071390. [PMID: 36713366 PMCID: PMC9877314 DOI: 10.3389/fimmu.2022.1071390] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2022] [Accepted: 12/28/2022] [Indexed: 01/15/2023] Open
Abstract
Telomerase, an RNA-dependent DNA polymerase synthesizing telomeric TTAGGG sequences, is primarily silent in normal human urothelial cells (NHUCs), but widely activated in urothelial cell-derived carcinomas or urothelial carcinomas (UCs) including UC of the bladder (UCB) and upper track UC (UTUC). Telomerase activation for telomere maintenance is required for the UC development and progression, and the key underlying mechanism is the transcriptional de-repression of the telomerase reverse transcriptase (TERT), a gene encoding the rate-limiting, telomerase catalytic component. Recent mechanistic explorations have revealed important roles for TERT promoter mutations and aberrant methylation in activation of TERT transcription and telomerase in UCs. Moreover, these TERT-featured genomic and epigenetic alterations have been evaluated for their usefulness in non-invasive UC diagnostics, recurrence monitoring, outcome prediction and response to treatments such as immunotherapy. Importantly, the detection of the mutated TERT promoter and TERT mRNA as urinary biomarkers holds great promise for urine-based UC liquid biopsy. In the present article, we review recent mechanistic insights into altered TERT promoter-mediated telomerase activation in UCs and discuss potential clinical implications. Specifically, we compare differences in senescence and transformation between NHUCs and other types of epithelial cells, address the interaction between TERT promoter mutations and other factors to affect UC progression and outcomes, evaluate the impact of TERT promoter mutations and TERT-mediated activation of human endogenous retrovirus genes on UC immunotherapy including Bacillus Calmette-Guérin therapy and immune checkpoint inhibitors. Finally, we suggest the standardization of a TERT assay and evaluation system for UC clinical practice.
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Affiliation(s)
- Tiantian Liu
- Department of Pathology, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Shihong Li
- Department of Pathology, Maternal and Child Health Hospital of Liaocheng, Liaocheng, China
| | - Chuanyou Xia
- Department of Urology, The First Affiliated Hospital of Shandong First Medical University & Shandong Provincial Qianfoshan Hospital, Jinan, China,*Correspondence: Chuanyou Xia, ; Dawei Xu,
| | - Dawei Xu
- Department of Medicine, Bioclinicum and Center for Molecular Medicine (CMM), Karolinska Institutet and Karolinska University Hospital Solna, Stockholm, Sweden,*Correspondence: Chuanyou Xia, ; Dawei Xu,
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17
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Slusher AL, Kim JJJ, Ribick M, Pollens-Voigt J, Bankhead A, Palmbos PL, Ludlow AT. Intronic Cis-Element DR8 in hTERT Is Bound by Splicing Factor SF3B4 and Regulates hTERT Splicing in Non-Small Cell Lung Cancer. Mol Cancer Res 2022; 20:1574-1588. [PMID: 35852380 PMCID: PMC9532359 DOI: 10.1158/1541-7786.mcr-21-0058] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 11/14/2021] [Accepted: 06/14/2022] [Indexed: 11/16/2022]
Abstract
Splicing of the hTERT gene to produce the full-length (FL) transcript is necessary for telomerase enzyme activity and telomere-dependent cellular immortality in the majority of human tumors, including non-small cell lung cancer (NSCLC) cells. The molecular machinery to splice hTERT to the FL isoform remains mostly unknown. Previously, we reported that an intron 8 cis-element termed "direct repeat 8" (DR8) promotes FL hTERT splicing, telomerase, and telomere length maintenance when bound by NOVA1 and PTBP1 in NSCLC cells. However, some NSCLC cells and patient tumor samples lack NOVA1 expression. This leaves a gap in knowledge about the splicing factors and cis-elements that promote telomerase in the NOVA1-negative context. We report that DR8 regulates FL hTERT splicing in the NOVA1-negative and -positive lung cancer contexts. We identified splicing factor 3b subunit 4 (SF3B4) as an RNA trans-factor whose expression is increased in lung adenocarcinoma (LUAD) tumors compared with adjacent normal tissue and predicts poor LUAD patient survival. In contrast to normal lung epithelial cells, which continued to grow with partial reductions of SF3B4 protein, SF3B4 knockdown reduced hTERT splicing, telomerase activity, telomere length, and cell growth in lung cancer cells. SF3B4 was also demonstrated to bind the DR8 region of hTERT pre-mRNA in both NOVA1-negative and -positive NSCLC cells. These findings provide evidence that DR8 is a critical binding hub for trans-factors to regulate FL hTERT splicing in NSCLC cells. These studies help define mechanisms of gene regulation important to the generation of telomerase activity during carcinogenesis. IMPLICATIONS Manipulation of a core spliceosome protein reduces telomerase/hTERT splicing in lung cancer cells and results in slowed cancer cell growth and cell death, revealing a potential therapeutic strategy.
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Affiliation(s)
- Aaron L. Slusher
- School of Kinesiology, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Jeongjin JJ Kim
- School of Kinesiology, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Mark Ribick
- School of Kinesiology, University of Michigan, Ann Arbor, MI, 48109, USA
| | | | - Armand Bankhead
- Biostatistics Department and School of Public Health, University of Michigan, Ann Arbor, MI, 48109, USA
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Phillip L. Palmbos
- Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor, MI, 48109, USA
| | - Andrew T. Ludlow
- School of Kinesiology, University of Michigan, Ann Arbor, MI, 48109, USA
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18
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Batista LFZ, Dokal I, Parker R. Telomere biology disorders: time for moving towards the clinic? Trends Mol Med 2022; 28:882-891. [PMID: 36057525 PMCID: PMC9509473 DOI: 10.1016/j.molmed.2022.08.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 07/29/2022] [Accepted: 08/01/2022] [Indexed: 11/19/2022]
Abstract
Telomere biology disorders (TBDs) are a group of rare diseases caused by mutations that impair telomere maintenance. Mutations that cause reduced levels of TERC/hTR, the telomerase RNA component, are found in most TBD patients and include loss-of-function mutations in hTR itself, in hTR-binding proteins [NOP10, NHP2, NAF1, ZCCHC8, and dyskerin (DKC1)], and in proteins required for hTR processing (PARN). These patients show diverse clinical presentations that most commonly include bone marrow failure (BMF)/aplastic anemia (AA), pulmonary fibrosis, and liver cirrhosis. There are no curative therapies for TBD patients. An understanding of hTR biogenesis, maturation, and degradation has identified pathways and pharmacological agents targeting the poly(A) polymerase PAPD5, which adds 3'-oligoadenosine tails to hTR to promote hTR degradation, and TGS1, which modifies the 5'-cap structure of hTR to enhance degradation, as possible therapeutic approaches. Critical next steps will be clinical trials to establish the effectiveness and potential side effects of these compounds in TBD patients.
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Affiliation(s)
- Luis F Z Batista
- Department of Medicine, Washington University in St. Louis, St. Louis, MO, USA; Center for Genome Integrity, Washington University in St. Louis, St. Louis, MO, USA; Center of Regenerative Medicine, Washington University in St. Louis, St. Louis, MO, USA.
| | - Inderjeet Dokal
- Centre for Genomics and Child Health, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
| | - Roy Parker
- Department of Biochemistry and Biofrontiers Instiute, University of Colorado, Boulder, CO, USA; Department of Biochemistry, University of Colorado Boulder, Boulder, CO, USA; Howard Hughes Medical Institute, Chevy Chase, MD, USA.
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19
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Abstract
The number of (TTAGGG)n repeats at the ends of chromosomes is highly variable between individual chromosomes, between different cells and between species. Progressive loss of telomere repeats limits the proliferation of pre-malignant human cells but also contributes to aging by inducing apoptosis and senescence in normal cells. Despite enormous progress in understanding distinct pathways that result in loss and gain of telomeric DNA in different cell types, many questions remain. Further studies are needed to delineate the role of damage to telomeric DNA, replication errors, chromatin structure, liquid-liquid phase transition, telomeric transcripts (TERRA) and secondary DNA structures such as guanine quadruplex structures, R-loops and T-loops in inducing gains and losses of telomere repeats in different cell types. Limitations of current telomere length measurements techniques and differences in telomere biology between species and different cell types complicate generalizations about the role of telomeres in aging and cancer. Here some of the factors regulating the telomere length in embryonic and adult cells in mammals are discussed from a mechanistic and evolutionary perspective.
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Affiliation(s)
- Peter Lansdorp
- Terry Fox Laboratory, British Columbia (BC) Cancer Agency, Vancouver, BC, Canada
- Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
- *Correspondence: Peter Lansdorp,
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20
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Functional interaction between compound heterozygous TERT mutations causes severe telomere biology disorder. Blood Adv 2022; 6:3779-3791. [PMID: 35477117 DOI: 10.1182/bloodadvances.2022007029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 04/07/2022] [Indexed: 11/20/2022] Open
Abstract
Telomere biology disorders (TBDs) are a spectrum of multisystem inherited disorders characterized by bone marrow failure, resulting from mutations in genes encoding telomerase or other proteins involved in maintaining telomere length and integrity. Pathogenicity of variants in these genes can be hard to evaluate, since TBD mutations show highly variable penetrance and genetic anticipation due to inheritance of shorter telomeres with each generation. Thus, detailed functional analysis of newly identified variants is often essential. Here we describe a patient with compound heterozygous variants in the TERT gene, which encodes the catalytic subunit of telomerase, hTERT; this patient has the extremely severe Hoyeraal-Hreidarsson form of TBD, although his heterozygous parents are clinically unaffected. Molecular dynamic modeling and detailed biochemical analyses demonstrate that 1 allele (L557P) affects association of hTERT with its cognate RNA component hTR, while the other (K1050E) affects the binding of telomerase to its DNA substrate and enzyme processivity. Unexpectedly, the data demonstrate a functional interaction between the proteins encoded by the 2 alleles, with WT hTERT able to rescue the effect of K1050E on processivity, whereas L557P hTERT cannot. These data contribute to the mechanistic understanding of telomerase, indicating that RNA binding in 1 hTERT molecule affects the processivity of telomere addition by the other molecule. This work emphasizes the importance of functional characterization of TERT variants to reach a definitive molecular diagnosis for TBD patients, and in particular it illustrates the importance of analyzing the effects of compound heterozygous variants in combination to reveal interallelic effects.
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21
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Lansdorp PM. Telomeres, aging, and cancer: the big picture. Blood 2022; 139:813-821. [PMID: 35142846 PMCID: PMC8832478 DOI: 10.1182/blood.2021014299] [Citation(s) in RCA: 56] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 12/16/2021] [Indexed: 12/13/2022] Open
Abstract
The role of telomeres in human health and disease is yet to be fully understood. The limitations of mouse models for the study of human telomere biology and difficulties in accurately measuring the length of telomere repeats in chromosomes and cells have diverted attention from many important and relevant observations. The goal of this perspective is to summarize some of these observations and to discuss the antagonistic role of telomere loss in aging and cancer in the context of developmental biology, cell turnover, and evolution. It is proposed that both damage to DNA and replicative loss of telomeric DNA contribute to aging in humans, with the differences in leukocyte telomere length between humans being linked to the risk of developing specific diseases. These ideas are captured in the Telomere Erosion in Disposable Soma theory of aging proposed herein.
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Affiliation(s)
- Peter M Lansdorp
- Terry Fox Laboratory, BC Cancer Agency, Vancouver, BC, Canada; and Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
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22
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Stem cells at odds with telomere maintenance and protection. Trends Cell Biol 2022; 32:527-536. [DOI: 10.1016/j.tcb.2021.12.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 12/20/2021] [Accepted: 12/22/2021] [Indexed: 11/23/2022]
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23
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Stemm-Wolf AJ, O’Toole ET, Sheridan RM, Morgan JT, Pearson CG. The SON RNA splicing factor is required for intracellular trafficking structures that promote centriole assembly and ciliogenesis. Mol Biol Cell 2021; 32:ar4. [PMID: 34406792 PMCID: PMC8684746 DOI: 10.1091/mbc.e21-06-0305] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 07/16/2021] [Accepted: 07/23/2021] [Indexed: 11/11/2022] Open
Abstract
Control of centrosome assembly is critical for cell division, intracellular trafficking, and cilia. Regulation of centrosome number occurs through the precise duplication of centrioles that reside in centrosomes. Here we explored transcriptional control of centriole assembly and find that the RNA splicing factor SON is specifically required for completing procentriole assembly. Whole genome mRNA sequencing identified genes whose splicing and expression are affected by the reduction of SON, with an enrichment in genes involved in the microtubule (MT) cytoskeleton, centrosome, and centriolar satellites. SON is required for the proper splicing and expression of CEP131, which encodes a major centriolar satellite protein and is required to organize the trafficking and MT network around the centrosomes. This study highlights the importance of the distinct MT trafficking network that is intimately associated with nascent centrioles and is responsible for procentriole development and efficient ciliogenesis.
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Affiliation(s)
- Alexander J. Stemm-Wolf
- Department of Cell and Developmental Biology, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045
| | | | - Ryan M. Sheridan
- RNA Biosciences Initiative (RBI), University of Colorado, Anschutz Medical Campus, Aurora, CO 80045
| | - Jacob T. Morgan
- Department of Cell and Developmental Biology, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045
| | - Chad G. Pearson
- Department of Cell and Developmental Biology, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045
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24
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Glousker G, Lingner J. Challenging endings: How telomeres prevent fragility. Bioessays 2021; 43:e2100157. [PMID: 34436787 DOI: 10.1002/bies.202100157] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 08/10/2021] [Accepted: 08/11/2021] [Indexed: 12/23/2022]
Abstract
It has become apparent that difficulties to replicate telomeres concern not only the very ends of eukaryotic chromosomes. The challenges already start when the replication fork enters the telomeric repeats. The obstacles encountered consist mainly of noncanonical nucleic acid structures that interfere with replication if not resolved. Replication stress at telomeres promotes the formation of so-called fragile telomeres displaying an abnormal appearance in metaphase chromosomes though their exact molecular nature remains to be elucidated. A substantial number of factors is required to counteract fragility. In this review we promote the hypothesis that telomere fragility is not caused directly by an initial insult during replication but it results as a secondary consequence of DNA repair of damaged replication forks by the homologous DNA recombination machinery. Incomplete DNA synthesis at repair sites or partial chromatin condensation may become apparent as telomere fragility. Fragility and DNA repair during telomere replication emerges as a common phenomenon which exacerbates in multiple disease conditions.
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Affiliation(s)
- Galina Glousker
- School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Swiss Institute for Experimental Cancer Research (ISREC), Lausanne, Switzerland
| | - Joachim Lingner
- School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Swiss Institute for Experimental Cancer Research (ISREC), Lausanne, Switzerland
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Rachakonda S, Hoheisel JD, Kumar R. Occurrence, functionality and abundance of the TERT promoter mutations. Int J Cancer 2021; 149:1852-1862. [PMID: 34313327 DOI: 10.1002/ijc.33750] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 06/14/2021] [Accepted: 07/16/2021] [Indexed: 12/18/2022]
Abstract
Telomere shortening at chromosomal ends due to the constraints of the DNA replication process acts as a tumor suppressor by restricting the replicative potential in primary cells. Cancers evade that limitation primarily through the reactivation of telomerase via different mechanisms. Mutations within the promoter of the telomerase reverse transcriptase (TERT) gene represent a definite mechanism for the ribonucleic enzyme regeneration predominantly in cancers that arise from tissues with low rates of self-renewal. The promoter mutations cause a moderate increase in TERT transcription and consequent telomerase upregulation to the levels sufficient to delay replicative senescence but not prevent bulk telomere shortening and genomic instability. Since the discovery, a staggering number of studies have resolved the discrete aspects, effects and clinical relevance of the TERT promoter mutations. The promoter mutations link transcription of TERT with oncogenic pathways, associate with markers of poor outcome and define patients with reduced survivals in several cancers. In this review, we discuss the occurrence and impact of the promoter mutations and highlight the mechanism of TERT activation. We further deliberate on the foundational question of the abundance of the TERT promoter mutations and a general dearth of functional mutations within noncoding sequences, as evident from pan-cancer analysis of the whole-genomes. We posit that the favorable genomic constellation within the TERT promoter may be less than a common occurrence in other noncoding functional elements. Besides, the evolutionary constraints limit the functional fraction within the human genome, hence the lack of abundant mutations outside the coding sequences.
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Affiliation(s)
| | - Jörg D Hoheisel
- Division of Functional Genome Analysis, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Rajiv Kumar
- Division of Functional Genome Analysis, German Cancer Research Center (DKFZ), Heidelberg, Germany.,Department of Molecular Biology of Cancer, Institute of Experimental Medicine of the Czech Academy of Sciences, Prague, Czech Republic
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Novo CL. A Tale of Two States: Pluripotency Regulation of Telomeres. Front Cell Dev Biol 2021; 9:703466. [PMID: 34307383 PMCID: PMC8300013 DOI: 10.3389/fcell.2021.703466] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Accepted: 06/08/2021] [Indexed: 01/01/2023] Open
Abstract
Inside the nucleus, chromatin is functionally organized and maintained as a complex three-dimensional network of structures with different accessibility such as compartments, lamina associated domains, and membraneless bodies. Chromatin is epigenetically and transcriptionally regulated by an intricate and dynamic interplay of molecular processes to ensure genome stability. Phase separation, a process that involves the spontaneous organization of a solution into separate phases, has been proposed as a mechanism for the timely coordination of several cellular processes, including replication, transcription and DNA repair. Telomeres, the repetitive structures at the end of chromosomes, are epigenetically maintained in a repressed heterochromatic state that prevents their recognition as double-strand breaks (DSB), avoiding DNA damage repair and ensuring cell proliferation. In pluripotent embryonic stem cells, telomeres adopt a non-canonical, relaxed epigenetic state, which is characterized by a low density of histone methylation and expression of telomere non-coding transcripts (TERRA). Intriguingly, this telomere non-canonical conformation is usually associated with chromosome instability and aneuploidy in somatic cells, raising the question of how genome stability is maintained in a pluripotent background. In this review, we will explore how emerging technological and conceptual developments in 3D genome architecture can provide novel mechanistic perspectives for the pluripotent epigenetic paradox at telomeres. In particular, as RNA drives the formation of LLPS, we will consider how pluripotency-associated high levels of TERRA could drive and coordinate phase separation of several nuclear processes to ensure genome stability. These conceptual advances will provide a better understanding of telomere regulation and genome stability within the highly dynamic pluripotent background.
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Affiliation(s)
- Clara Lopes Novo
- The Francis Crick Institute, London, United Kingdom
- Imperial College London, London, United Kingdom
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27
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Alternative splicing regulates telomerase repression. Nat Rev Genet 2021; 22:414. [PMID: 33963358 DOI: 10.1038/s41576-021-00372-6] [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]
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