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Prince S, Maguemoun K, Ferdebouh M, Querido E, Derumier A, Tremblay S, Chartrand P. CoPixie, a novel algorithm for single-particle track colocalization, enables efficient quantification of telomerase dynamics at telomeres. Nucleic Acids Res 2024; 52:9417-9430. [PMID: 39082280 PMCID: PMC11381360 DOI: 10.1093/nar/gkae669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Revised: 07/16/2024] [Accepted: 07/22/2024] [Indexed: 09/10/2024] Open
Abstract
Single-particle imaging and tracking can be combined with colocalization analysis to study the dynamic interactions between macromolecules in living cells. Indeed, single-particle tracking has been extensively used to study protein-DNA interactions and dynamics. Still, unbiased identification and quantification of binding events at specific genomic loci remains challenging. Herein, we describe CoPixie, a new software that identifies colocalization events between a theoretically unlimited number of imaging channels, including single-particle movies. CoPixie is an object-based colocalization algorithm that relies on both pixel and trajectory overlap to determine colocalization between molecules. We employed CoPixie with live-cell single-molecule imaging of telomerase and telomeres, to test the model that cancer-associated POT1 mutations facilitate telomere accessibility. We show that POT1 mutants Y223C, D224N or K90E increase telomere accessibility for telomerase interaction. However, unlike the POT1-D224N mutant, the POT1-Y223C and POT1-K90E mutations also increase the duration of long-lasting telomerase interactions at telomeres. Our data reveal that telomere elongation in cells expressing cancer-associated POT1 mutants arises from the dual impact of these mutations on telomere accessibility and telomerase retention at telomeres. CoPixie can be used to explore a variety of questions involving macromolecular interactions in living cells, including between proteins and nucleic acids, from multicolor single-particle tracks.
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Affiliation(s)
- Samuel Prince
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Québec H3T 1J4, Canada
| | - Kamélia Maguemoun
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Québec H3T 1J4, Canada
| | - Mouna Ferdebouh
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Québec H3T 1J4, Canada
| | - Emmanuelle Querido
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Québec H3T 1J4, Canada
| | - Amélie Derumier
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Québec H3T 1J4, Canada
| | - Stéphanie Tremblay
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Québec H3T 1J4, Canada
| | - Pascal Chartrand
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Québec H3T 1J4, Canada
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2
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Stockhammer A, Spalt C, Klemt A, Benz LS, Harel S, Natalia V, Wiench L, Freund C, Kuropka B, Bottanelli F. When less is more - a fast TurboID knock-in approach for high-sensitivity endogenous interactome mapping. J Cell Sci 2024; 137:jcs261952. [PMID: 39056144 PMCID: PMC11385326 DOI: 10.1242/jcs.261952] [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: 01/11/2024] [Accepted: 07/10/2024] [Indexed: 07/28/2024] Open
Abstract
In recent years, proximity labeling has established itself as an unbiased and powerful approach to map the interactome of specific proteins. Although physiological expression of labeling enzymes is beneficial for the mapping of interactors, generation of the desired cell lines remains time-consuming and challenging. Using our established pipeline for rapid generation of C- and N-terminal CRISPR-Cas9 knock-ins (KIs) based on antibiotic selection, we were able to compare the performance of commonly used labeling enzymes when endogenously expressed. Endogenous tagging of the µ subunit of the adaptor protein (AP)-1 complex with TurboID allowed identification of known interactors and cargo proteins that simple overexpression of a labeling enzyme fusion protein could not reveal. We used the KI strategy to compare the interactome of the different AP complexes and clathrin and were able to assemble lists of potential interactors and cargo proteins that are specific for each sorting pathway. Our approach greatly simplifies the execution of proximity labeling experiments for proteins in their native cellular environment and allows going from CRISPR transfection to mass spectrometry analysis and interactome data in just over a month.
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Affiliation(s)
- Alexander Stockhammer
- Membrane Trafficking Laboratory, Institute for Chemistry and Biochemistry, Freie Universität Berlin, Thielallee 63, 14195 Berlin, Germany
| | - Carissa Spalt
- Membrane Trafficking Laboratory, Institute for Chemistry and Biochemistry, Freie Universität Berlin, Thielallee 63, 14195 Berlin, Germany
| | - Antonia Klemt
- Membrane Trafficking Laboratory, Institute for Chemistry and Biochemistry, Freie Universität Berlin, Thielallee 63, 14195 Berlin, Germany
| | - Laila S Benz
- Membrane Trafficking Laboratory, Institute for Chemistry and Biochemistry, Freie Universität Berlin, Thielallee 63, 14195 Berlin, Germany
| | - Shelly Harel
- Membrane Trafficking Laboratory, Institute for Chemistry and Biochemistry, Freie Universität Berlin, Thielallee 63, 14195 Berlin, Germany
| | - Vini Natalia
- Membrane Trafficking Laboratory, Institute for Chemistry and Biochemistry, Freie Universität Berlin, Thielallee 63, 14195 Berlin, Germany
| | - Lukas Wiench
- Membrane Trafficking Laboratory, Institute for Chemistry and Biochemistry, Freie Universität Berlin, Thielallee 63, 14195 Berlin, Germany
| | - Christian Freund
- Laboratory of Protein Biochemistry, Institute for Chemistry and Biochemistry, Freie Universität Berlin, Thielallee 63, 14195 Berlin, Germany
| | - Benno Kuropka
- Laboratory of Protein Biochemistry, Institute for Chemistry and Biochemistry, Freie Universität Berlin, Thielallee 63, 14195 Berlin, Germany
| | - Francesca Bottanelli
- Membrane Trafficking Laboratory, Institute for Chemistry and Biochemistry, Freie Universität Berlin, Thielallee 63, 14195 Berlin, Germany
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3
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Li B, Xiong W, Zuo W, Shi Y, Wang T, Chang L, Wu Y, Ma H, Bian Q, Chang ACY. Proximal telomeric decompaction due to telomere shortening drives FOXC1-dependent myocardial senescence. Nucleic Acids Res 2024; 52:6269-6284. [PMID: 38634789 PMCID: PMC11194093 DOI: 10.1093/nar/gkae274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 02/29/2024] [Accepted: 04/03/2024] [Indexed: 04/19/2024] Open
Abstract
Telomeres, TTAGGGn DNA repeat sequences located at the ends of eukaryotic chromosomes, play a pivotal role in aging and are targets of DNA damage response. Although we and others have demonstrated presence of short telomeres in genetic cardiomyopathic and heart failure cardiomyocytes, little is known about the role of telomere lengths in cardiomyocyte. Here, we demonstrate that in heart failure patient cardiomyocytes, telomeres are shortened compared to healthy controls. We generated isogenic human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CMs) with short telomeres (sTL-CMs) and normal telomeres (nTL-CMs) as model. Compared to nTL-CMs, short telomeres result in cardiac dysfunction and expression of senescent markers. Using Hi-C and RNASeq, we observe that short telomeres induced TAD insulation decrease near telomeric ends and this correlated with a transcription upregulation in sTL-CMs. FOXC1, a key transcription factor involved in early cardiogenesis, was upregulated in sTL-CMs and its protein levels were negatively correlated with telomere lengths in heart failure patients. Overexpression of FOXC1 induced hiPSC-CM aging, mitochondrial and contractile dysfunction; knockdown of FOXC1 rescued these phenotypes. Overall, the work presented demonstrate that increased chromatin accessibility due to telomere shortening resulted in the induction of FOXC1-dependent expression network responsible for contractile dysfunction and myocardial senescence.
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Affiliation(s)
- Bin Li
- Department of Cardiology and Shanghai Institute of Precision Medicine, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200125, China
| | - Weiyao Xiong
- Department of Cardiology and Shanghai Institute of Precision Medicine, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200125, China
| | - Wu Zuo
- Department of Cardiology and Shanghai Institute of Precision Medicine, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200125, China
| | - Yuanyuan Shi
- Department of Cardiology and Shanghai Institute of Precision Medicine, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200125, China
| | - Teng Wang
- Department of Cardiology and Shanghai Institute of Precision Medicine, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200125, China
| | - Lingling Chang
- Department of Cardiology and Shanghai Institute of Precision Medicine, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200125, China
| | - Yueheng Wu
- Department of Cardiovascular Medicine, Guangdong General Hospital, Guangzhou, Guangdong, China
| | - Heng Ma
- Department of Physiology and Pathophysiology, Fourth Military Medical University, No. 169 Changle West Rd, Xi'an 710032, China
| | - Qian Bian
- Department of Cardiology and Shanghai Institute of Precision Medicine, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200125, China
| | - Alex C Y Chang
- Department of Cardiology and Shanghai Institute of Precision Medicine, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200125, China
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4
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Bettin N, Querido E, Gialdini I, Grupelli GP, Goretti E, Cantarelli M, Andolfato M, Soror E, Sontacchi A, Jurikova K, Chartrand P, Cusanelli E. TERRA transcripts localize at long telomeres to regulate telomerase access to chromosome ends. SCIENCE ADVANCES 2024; 10:eadk4387. [PMID: 38865460 PMCID: PMC11168465 DOI: 10.1126/sciadv.adk4387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Accepted: 05/08/2024] [Indexed: 06/14/2024]
Abstract
The function of TERRA in the regulation of telomerase in human cells is still debated. While TERRA interacts with telomerase, how it regulates telomerase function remains unknown. Here, we show that TERRA colocalizes with the telomerase RNA subunit hTR in the nucleoplasm and at telomeres during different phases of the cell cycle. We report that TERRA transcripts relocate away from chromosome ends during telomere lengthening, leading to a reduced number of telomeric TERRA-hTR molecules and consequent increase in "TERRA-free" telomerase molecules at telomeres. Using live-cell imaging and super-resolution microscopy, we show that upon transcription, TERRA relocates from its telomere of origin to long chromosome ends. Furthermore, TERRA depletion by antisense oligonucleotides promoted hTR localization to telomeres, leading to increased residence time and extended half-life of hTR molecules at telomeres. Overall, our findings indicate that telomeric TERRA transcripts inhibit telomere elongation by telomerase acting in trans, impairing telomerase access to telomeres that are different from their chromosome end of origin.
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Affiliation(s)
- Nicole Bettin
- Laboratory of Cell Biology and Molecular Genetics, Department CIBIO, University of Trento, via Sommarive 9, 38123 Trento, Italy
| | - Emmanuelle Querido
- Department of Biochemistry and Molecular Medicine, University of Montreal, 2900 boul. Edouard Montpetit, H3T1J4 Montreal, Canada
| | - Irene Gialdini
- Laboratory of Cell Biology and Molecular Genetics, Department CIBIO, University of Trento, via Sommarive 9, 38123 Trento, Italy
| | - Glenda Paola Grupelli
- Laboratory of Cell Biology and Molecular Genetics, Department CIBIO, University of Trento, via Sommarive 9, 38123 Trento, Italy
| | - Elena Goretti
- Laboratory of Cell Biology and Molecular Genetics, Department CIBIO, University of Trento, via Sommarive 9, 38123 Trento, Italy
| | - Marta Cantarelli
- Laboratory of Cell Biology and Molecular Genetics, Department CIBIO, University of Trento, via Sommarive 9, 38123 Trento, Italy
| | - Marta Andolfato
- Laboratory of Cell Biology and Molecular Genetics, Department CIBIO, University of Trento, via Sommarive 9, 38123 Trento, Italy
| | - Eslam Soror
- Laboratory of Cell Biology and Molecular Genetics, Department CIBIO, University of Trento, via Sommarive 9, 38123 Trento, Italy
| | - Alessandra Sontacchi
- Laboratory of Cell Biology and Molecular Genetics, Department CIBIO, University of Trento, via Sommarive 9, 38123 Trento, Italy
| | - Katarina Jurikova
- Laboratory of Cell Biology and Molecular Genetics, Department CIBIO, University of Trento, via Sommarive 9, 38123 Trento, Italy
- Department of Genetics, Faculty of Natural Sciences, Comenius University in Bratislava, Ilkovičova 6, Mlynská dolina, 84215 Bratislava, Slovakia
| | - Pascal Chartrand
- Department of Biochemistry and Molecular Medicine, University of Montreal, 2900 boul. Edouard Montpetit, H3T1J4 Montreal, Canada
| | - Emilio Cusanelli
- Laboratory of Cell Biology and Molecular Genetics, Department CIBIO, University of Trento, via Sommarive 9, 38123 Trento, Italy
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5
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Bartle L, Wellinger RJ. Methods that shaped telomerase research. Biogerontology 2024; 25:249-263. [PMID: 37903970 PMCID: PMC10998806 DOI: 10.1007/s10522-023-10073-8] [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: 08/08/2023] [Accepted: 09/30/2023] [Indexed: 11/01/2023]
Abstract
Telomerase, the ribonucleoprotein (RNP) responsible for telomere maintenance, has a complex life. Complex in that it is made of multiple proteins and an RNA, and complex because it undergoes many changes, and passes through different cell compartments. As such, many methods have been developed to discover telomerase components, delve deep into understanding its structure and function and to figure out how telomerase biology ultimately relates to human health and disease. While some old gold-standard methods are still key for determining telomere length and measuring telomerase activity, new technologies are providing promising new ways to gain detailed information that we have never had access to before. Therefore, we thought it timely to briefly review the methods that have revealed information about the telomerase RNP and outline some of the remaining questions that could be answered using new methodology.
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Affiliation(s)
- Louise Bartle
- Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Applied Cancer Research Pavilion, 3201 rue Jean-Mignault, Sherbrooke, QC, J1E 4K8, Canada
| | - Raymund J Wellinger
- Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Applied Cancer Research Pavilion, 3201 rue Jean-Mignault, Sherbrooke, QC, J1E 4K8, Canada.
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6
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Paul S, McCourt PM, Le LTM, Ryu J, Czaja W, Bode AM, Contreras-Galindo R, Dong Z. Fyn-mediated phosphorylation of Menin disrupts telomere maintenance in stem cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.10.04.560876. [PMID: 37873235 PMCID: PMC10592958 DOI: 10.1101/2023.10.04.560876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Telomeres protect chromosome ends and determine the replication potential of dividing cells. The canonical telomere sequence TTAGGG is synthesized by telomerase holoenzyme, which maintains telomere length in proliferative stem cells. Although the core components of telomerase are well-defined, mechanisms of telomerase regulation are still under investigation. We report a novel role for the Src family kinase Fyn, which disrupts telomere maintenance in stem cells by phosphorylating the scaffold protein Menin. We found that Fyn knockdown prevented telomere erosion in human and mouse stem cells, validating the results with four telomere measurement techniques. We show that Fyn phosphorylates Menin at tyrosine 603 (Y603), which increases Menin's SUMO1 modification, C-terminal stability, and importantly, its association with the telomerase RNA component (TR). Using mass spectrometry, immunoprecipitation, and immunofluorescence experiments we found that SUMO1-Menin decreases TR's association with telomerase subunit Dyskerin, suggesting that Fyn's phosphorylation of Menin induces telomerase subunit mislocalization and may compromise telomerase function at telomeres. Importantly, we find that Fyn inhibition reduces accelerated telomere shortening in human iPSCs harboring mutations for dyskeratosis congenita.
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Affiliation(s)
- Souren Paul
- The Hormel Institute, University of Minnesota, 801 16th Avenue NE, Austin, MN 55912, USA
| | - Preston M. McCourt
- The Hormel Institute, University of Minnesota, 801 16th Avenue NE, Austin, MN 55912, USA
| | - Le Thi My Le
- The Hormel Institute, University of Minnesota, 801 16th Avenue NE, Austin, MN 55912, USA
| | - Joohyun Ryu
- The Hormel Institute, University of Minnesota, 801 16th Avenue NE, Austin, MN 55912, USA
- Department of Laboratory Medicine and Pathology, University of Minnesota School of Medicine, Minneapolis, MN, USA
| | - Wioletta Czaja
- The Hormel Institute, University of Minnesota, 801 16th Avenue NE, Austin, MN 55912, USA
- Department of Genetics, University of Alabama, Birmingham, AL 35294, USA
| | - Ann M. Bode
- The Hormel Institute, University of Minnesota, 801 16th Avenue NE, Austin, MN 55912, USA
| | - Rafael Contreras-Galindo
- The Hormel Institute, University of Minnesota, 801 16th Avenue NE, Austin, MN 55912, USA
- Department of Genetics, University of Alabama, Birmingham, AL 35294, USA
| | - Zigang Dong
- Department of Pathophysiology, School of Basic Medical Sciences, College of Medicine, Zhengzhou University, Henan, China 450001
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7
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Wang LJ, Liu WJ, Wang LY, Ho YP, Han Y, Li DL, Zhang CY. Construction of an Enzymatically Controlled DNA Nanomachine for One-Step Imaging of Telomerase in Living Cells. Anal Chem 2024; 96:4647-4656. [PMID: 38441540 DOI: 10.1021/acs.analchem.3c05795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/20/2024]
Abstract
Telomerase is a basic reverse transcriptase that maintains the telomere length in cells, and accurate and specific sensing of telomerase in living cells is critical for medical diagnostics and disease therapeutics. Herein, we demonstrate for the first time the construction of an enzymatically controlled DNA nanomachine with endogenous apurinic/apyrimidinic endonuclease 1 (APE1) as a driving force for one-step imaging of telomerase in living cells. The DNA nanomachine is designed by rational engineering of substrate probes and reporter probes embedded with an enzyme-activatable site (i.e., AP site) and their subsequent assembly on a gold nanoparticle (AuNP). Upon recognition and cleavage of the AP site in the substrate probe by APE1, the loop of the substrate probe unfolds, exposing telomeric primer (TP) with the 3'-OH end. Subsequently, the TP is elongated by telomerase at the 3'-OH end to generate a long telomeric product. The resultant telomeric product acts as a swing arm that can hybridize with a reporter probe to initiate the APE1-powered walking reaction, ultimately generating a significantly enhanced fluorescence signal. Notably, endogenous APE1 is used as the driving force of the DNA nanomachine, avoiding the introduction of exogenous auxiliary cofactors into the cellular microenvironment. Owing to the high kinetics and high amplification efficiency of the APE1-powered DNA nanomachine, this strategy enables one-step sensitive sensing of telomerase in vitro and in vivo. It can successfully discriminate telomerase activity between cancer cells and normal cells, screen telomerase inhibitors, and monitor the variations of telomerase activity in living cells, offering a prospective platform for molecular diagnostics and drug discovery.
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Affiliation(s)
- Li-Juan Wang
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, China
| | - Wen-Jing Liu
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, China
| | - Lu-Yao Wang
- College of Chemistry, Chemical Engineering and Materials Science, Shandong Normal University, Jinan 250014, China
| | - Yi-Ping Ho
- Department of Biomedical Engineering, The Chinese University of Hong Kong, Shatin, Hong Kong SAR 999077, China
| | - Yun Han
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, China
| | - Dong-Ling Li
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, China
| | - Chun-Yang Zhang
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, China
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8
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Lim CJ. Telomere C-Strand Fill-In Machinery: New Insights into the Human CST-DNA Polymerase Alpha-Primase Structures and Functions. Subcell Biochem 2024; 104:73-100. [PMID: 38963484 DOI: 10.1007/978-3-031-58843-3_5] [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: 07/05/2024]
Abstract
Telomeres at the end of eukaryotic chromosomes are extended by a specialized set of enzymes and telomere-associated proteins, collectively termed here the telomere "replisome." The telomere replisome acts on a unique replicon at each chromosomal end of the telomeres, the 3' DNA overhang. This telomere replication process is distinct from the replisome mechanism deployed to duplicate the human genome. The G-rich overhang is first extended before the complementary C-strand is filled in. This overhang is extended by telomerase, a specialized ribonucleoprotein and reverse transcriptase. The overhang extension process is terminated when telomerase is displaced by CTC1-STN1-TEN1 (CST), a single-stranded DNA-binding protein complex. CST then recruits DNA polymerase α-primase to complete the telomere replication process by filling in the complementary C-strand. In this chapter, the recent structure-function insights into the human telomere C-strand fill-in machinery (DNA polymerase α-primase and CST) will be discussed.
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Affiliation(s)
- Ci Ji Lim
- Department of Biochemistry, College of Agricultural and Life Sciences, University of Wisconsin-Madison, Madison, WI, USA.
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9
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Klump BM, Schmidt JC. Advances in understanding telomerase assembly. Biochem Soc Trans 2023; 51:2093-2101. [PMID: 38108475 PMCID: PMC10754283 DOI: 10.1042/bst20230269] [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: 09/05/2023] [Revised: 11/30/2023] [Accepted: 12/04/2023] [Indexed: 12/19/2023]
Abstract
Telomerase is a complex ribonucleoprotein scaffolded by the telomerase RNA (TR). Telomere lengthening by telomerase is essential to maintain the proliferative potential of stem cells and germ cells, and telomerase is inappropriately activated in the majority of cancers. Assembly of TR with its 12 protein co-factors and the maturation of the 5'- and 3'-ends of TR have been the focus of intense research efforts over the past two decades. High-resolution Cryo-EM structures of human telomerase, high-throughput sequencing of the 3' end of TR, and live cell imaging of various telomerase components have significantly advanced our understanding of the molecular mechanisms that govern telomerase biogenesis, yet many important questions remain unaddressed. In this review, we will summarize these recent advances and highlight the remaining key questions with the ultimate goal of targeting telomerase assembly to suppress telomere maintenance in cancer cells or to promote telomerase activity in patients affected by telomere shortening disorders.
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Affiliation(s)
- Basma M. Klump
- Institute for Quantitative Health Sciences and Engineering, Michigan State University, East Lansing, MI, U.S.A
- College of Osteopathic Medicine, Michigan State University, East Lansing, MI, U.S.A
- Cell and Molecular Biology Graduate Program, College of Natural Sciences, Michigan State University, East Lansing, MI, U.S.A
| | - Jens C. Schmidt
- Institute for Quantitative Health Sciences and Engineering, Michigan State University, East Lansing, MI, U.S.A
- Department of Obstetrics, Gynecology, and Reproductive Biology, Michigan State University, East Lansing, MI, U.S.A
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10
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Aureli S, Cardenas VB, Raniolo S, Limongelli V. Conformational plasticity and allosteric communication networks explain Shelterin protein TPP1 binding to human telomerase. Commun Chem 2023; 6:242. [PMID: 37935941 PMCID: PMC10630336 DOI: 10.1038/s42004-023-01040-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 10/24/2023] [Indexed: 11/09/2023] Open
Abstract
The Shelterin complex protein TPP1 interacts with human telomerase (TERT) by means of the TEL-patch region, controlling telomere homeostasis. Aberrations in the TPP1-TERT heterodimer formation might lead to short telomeres and severe diseases like dyskeratosis congenita and Hoyeraal-Hreidarsson syndrome. In the present study, we provide a thorough characterization of the structural properties of the TPP1's OB-domain by combining data coming from microsecond-long molecular dynamics calculations, time-series analyses, and graph-based networks. Our results show that the TEL-patch conformational freedom is influenced by a network of long-range amino acid communications that together determine the proper TPP1-TERT binding. Furthermore, we reveal that in TPP1 pathological variants Glu169Δ, Lys170Δ and Leu95Gln, the TEL-patch plasticity is reduced, affecting the correct binding to TERT and, in turn, telomere processivity, which eventually leads to accelerated aging of affected cells. Our study provides a structural basis for the design of TPP1-targeting ligands with therapeutic potential against cancer and telomeropathies.
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Affiliation(s)
- Simone Aureli
- Faculty of Biomedical Sciences, Euler Institute, Università della Svizzera italiana (USI), via G. Buffi 13, Lugano, CH-6900, Switzerland
- Institute of Pharmaceutical Sciences of Western Switzerland, University of Geneve, Rue Michel-Servet 1, Geneva, CH-1211, Switzerland
- Swiss Institute of Bioinformatics, University of Geneve, Geneva, CH-1206, Switzerland
| | - Vince Bart Cardenas
- Faculty of Biomedical Sciences, Euler Institute, Università della Svizzera italiana (USI), via G. Buffi 13, Lugano, CH-6900, Switzerland
| | - Stefano Raniolo
- Faculty of Biomedical Sciences, Euler Institute, Università della Svizzera italiana (USI), via G. Buffi 13, Lugano, CH-6900, Switzerland
| | - Vittorio Limongelli
- Faculty of Biomedical Sciences, Euler Institute, Università della Svizzera italiana (USI), via G. Buffi 13, Lugano, CH-6900, Switzerland.
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11
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He Q, Lim CJ. Models for human telomere C-strand fill-in by CST-Polα-primase. Trends Biochem Sci 2023; 48:860-872. [PMID: 37586999 PMCID: PMC10528720 DOI: 10.1016/j.tibs.2023.07.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Revised: 07/12/2023] [Accepted: 07/18/2023] [Indexed: 08/18/2023]
Abstract
Telomere maintenance is essential for the genome integrity of eukaryotes, and this function is underpinned by the two-step telomeric DNA synthesis process: telomere G-overhang extension by telomerase and complementary strand fill-in by DNA polymerase alpha-primase (polα-primase). Compared to the telomerase step, the telomere C-strand fill-in mechanism is less understood. Recent studies have provided new insights into how telomeric single-stranded DNA-binding protein CTC1-STN1-TEN1 (CST) and polα-primase coordinate to synthesize the telomeric C-strand for telomere overhang fill-in. Cryogenic electron microscopy (cryo-EM) structures of CST-polα-primase complexes have provided additional insights into how they assemble at telomeric templates and de novo synthesize the telomere C-strand. In this review, we discuss how these latest findings coalesce with existing understanding to develop a human telomere C-strand fill-in mechanism model.
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Affiliation(s)
- Qixiang He
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - Ci Ji Lim
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA.
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12
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Tu KJ, Stewart CE, Hendrickson PG, Regal JA, Kim SY, Ashley DM, Waitkus MS, Reitman ZJ. Pooled genetic screens to identify vulnerabilities in TERT-promoter-mutant glioblastoma. Oncogene 2023; 42:3274-3286. [PMID: 37741952 PMCID: PMC10615780 DOI: 10.1038/s41388-023-02845-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 09/08/2023] [Accepted: 09/15/2023] [Indexed: 09/25/2023]
Abstract
Pooled genetic screens represent a powerful approach to identify vulnerabilities in cancer. Here we used pooled CRISPR/Cas9-based approaches to identify vulnerabilities associated with telomerase reverse transcriptase (TERT) promoter mutations (TPMs) found in >80% of glioblastomas. We first developed a platform to detect perturbations that cause long-term growth defects in a TPM-mutated glioblastoma cell line. However, we could not detect dependencies on either TERT itself or on an E-twenty six transcription (ETS) factor known to activate TPMs. To explore this finding, we cataloged TPM status for 441 cell lines and correlated this with genome-wide screening data. We found that TPM status was not associated with differential dependency on TERT, but that E-twenty six (ETS) transcription factors represent key dependencies in both TPM+ and TPM- lines. Further, we found that TPMs are associated with expression of gene programs regulated by a wide array of ETS-factors in both cell lines and primary glioblastoma tissues. This work contributes a unique TPM cell line reagent, establishes TPM status for many deeply-profiled cell lines, and catalogs TPM-associated vulnerabilities. The results highlight challenges in executing genetic screens to detect TPM-specific vulnerabilities, and suggest redundancy in the genetic network that regulates TPM function with therapeutic implications.
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Affiliation(s)
- Kevin J Tu
- Department of Radiation Oncology, Duke University School of Medicine, Durham, NC, 27710, USA
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, 21044, USA
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Connor E Stewart
- Department of Radiation Oncology, Duke University School of Medicine, Durham, NC, 27710, USA
| | - Peter G Hendrickson
- Department of Radiation Oncology, Duke University School of Medicine, Durham, NC, 27710, USA
| | - Joshua A Regal
- Department of Radiation Oncology, Duke University School of Medicine, Durham, NC, 27710, USA
| | - So Young Kim
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC, 27710, USA
- Duke Cancer Institute, Duke University School of Medicine, Durham, NC, 27710, USA
| | - David M Ashley
- Duke Cancer Institute, Duke University School of Medicine, Durham, NC, 27710, USA
- Department of Neurosurgery, Duke University School of Medicine, Durham, NC, 27710, USA
- The Preston Robert Tisch Brain Tumor Center at Duke, Durham, NC, 27710, USA
| | - Matthew S Waitkus
- Duke Cancer Institute, Duke University School of Medicine, Durham, NC, 27710, USA
- Department of Neurosurgery, Duke University School of Medicine, Durham, NC, 27710, USA
- The Preston Robert Tisch Brain Tumor Center at Duke, Durham, NC, 27710, USA
| | - Zachary J Reitman
- Department of Radiation Oncology, Duke University School of Medicine, Durham, NC, 27710, USA.
- Duke Cancer Institute, Duke University School of Medicine, Durham, NC, 27710, USA.
- Department of Neurosurgery, Duke University School of Medicine, Durham, NC, 27710, USA.
- The Preston Robert Tisch Brain Tumor Center at Duke, Durham, NC, 27710, USA.
- Department of Pathology, Duke University School of Medicine, Durham, NC, 27710, USA.
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13
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Ebata H, Shima T, Iizuka R, Uemura S. Accumulation of TERT in mitochondria exerts two opposing effects on apoptosis. FEBS Open Bio 2023; 13:1667-1682. [PMID: 37525387 PMCID: PMC10476567 DOI: 10.1002/2211-5463.13682] [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: 06/15/2022] [Revised: 07/18/2023] [Accepted: 07/31/2023] [Indexed: 08/02/2023] Open
Abstract
Telomerase reverse transcriptase (TERT) is a protein that catalyzes the reverse transcription of telomere elongation. TERT is also expected to play a non-canonical role beyond telomere lengthening since it localizes not only in the nucleus but also in mitochondria, where telomeres do not exist. Several studies have reported that mitochondrial TERT regulates apoptosis induced by oxidative stress. However, there is still some controversy as to whether mitochondrial TERT promotes or inhibits apoptosis, mainly due to the lack of information on changes in TERT distribution in individual cells over time. Here, we simultaneously detected apoptosis and TERT localization after oxidative stress in individual HeLa cells by live-cell tracking. Single-cell tracking revealed that the stress-induced accumulation of TERT in mitochondria caused apoptosis, but that accumulation increased over time until cell death. The results suggest a new model in which mitochondrial TERT has two opposing effects at different stages of apoptosis: it predetermines apoptosis at the first stage of cell-fate determination, but also delays apoptosis at the second stage. As such, our data support a model that integrates the two opposing hypotheses on mitochondrial TERT's effect on apoptosis. Furthermore, detailed statistical analysis of TERT mutations, which have been predicted to inhibit TERT transport to mitochondria, revealed that these mutations suppress apoptosis independent of mitochondrial localization of TERT. Together, these results imply that the non-canonical functions of TERT affect a wide range of mitochondria-dependent and mitochondria-independent apoptosis pathways.
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Affiliation(s)
- Hiroshi Ebata
- Department of Biological Sciences, Graduate School of ScienceThe University of TokyoJapan
- Present address:
Buck Institute for Research on AgingNovatoCAUSA
| | - Tomohiro Shima
- Department of Biological Sciences, Graduate School of ScienceThe University of TokyoJapan
| | - Ryo Iizuka
- Department of Biological Sciences, Graduate School of ScienceThe University of TokyoJapan
| | - Sotaro Uemura
- Department of Biological Sciences, Graduate School of ScienceThe University of TokyoJapan
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14
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Heyza JR, Mikhova M, Schmidt JC. Live cell single-molecule imaging to study DNA repair in human cells. DNA Repair (Amst) 2023; 129:103540. [PMID: 37467632 PMCID: PMC10530516 DOI: 10.1016/j.dnarep.2023.103540] [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: 03/31/2023] [Revised: 06/29/2023] [Accepted: 07/05/2023] [Indexed: 07/21/2023]
Abstract
The genetic material in human cells is continuously exposed to a wide variety of insults that can induce different DNA lesions. To maintain genomic stability and prevent potentially deleterious genetic changes caused by DNA damage, mammalian cells have evolved a number of pathways that repair specific types of DNA damage. These DNA repair pathways vary in their accuracy, some providing high-fidelity repair while others are error-prone and are only activated as a last resort. Adding additional complexity to cellular mechanisms of DNA repair is the DNA damage response which is a sophisticated a signaling network that coordinates repair outcomes, cell-cycle checkpoint activation, and cell fate decisions. As a result of the sheer complexity of the various DNA repair pathways and the DNA damage response there are large gaps in our understanding of the molecular mechanisms underlying DNA damage repair in human cells. A key unaddressed question is how the dynamic recruitment of DNA repair factors contributes to repair kinetics and repair pathway choice in human cells. Methodological advances in live cell single-molecule imaging over the last decade now allow researchers to directly observe and analyze the dynamics of DNA repair proteins in living cells with high spatiotemporal resolution. Live cell single-molecule imaging combined with single-particle tracking can provide direct insight into the biochemical reactions that control DNA repair and has the power to identify previously unobservable processes in living cells. This review summarizes the main considerations for experimental design and execution for live cell single-molecule imaging experiments and describes how they can be used to define the molecular mechanisms of DNA damage repair in mammalian cells.
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Affiliation(s)
- Joshua R Heyza
- Institute for Quantitative Health Science and Engineering, Michigan State University, East Lansing, MI, USA
| | - Mariia Mikhova
- Institute for Quantitative Health Science and Engineering, Michigan State University, East Lansing, MI, USA; Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA
| | - Jens C Schmidt
- Institute for Quantitative Health Science and Engineering, Michigan State University, East Lansing, MI, USA; Department of Obstetrics, Gynecology, and Reproductive Biology, Michigan State University, East Lansing, MI, USA.
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15
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Shao X, Meng C, Song W, Zhang T, Chen Q. Subcellular visualization: Organelle-specific targeted drug delivery and discovery. Adv Drug Deliv Rev 2023; 199:114977. [PMID: 37391014 DOI: 10.1016/j.addr.2023.114977] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2023] [Revised: 06/22/2023] [Accepted: 06/26/2023] [Indexed: 07/02/2023]
Abstract
Organelles perform critical biological functions due to their distinct molecular composition and internal environment. Disorders in organelles or their interacting networks have been linked to the incidence of numerous diseases, and the research of pharmacological actions at the organelle level has sparked pharmacists' interest. Currently, cell imaging has evolved into a critical tool for drug delivery, drug discovery, and pharmacological research. The introduction of advanced imaging techniques in recent years has provided researchers with richer biological information for viewing and studying the ultrastructure of organelles, protein interactions, and gene transcription activities, leading to the design and delivery of precision-targeted drugs. Therefore, this reviews the research on organelles-targeted drugs based upon imaging technologies and development of fluorescent molecules for medicinal purposes. We also give a thorough analysis of a number of subcellular-level elements of drug development, including subcellular research instruments and methods, organelle biological event investigation, subcellular target and drug identification, and design of subcellular delivery systems. This review will make it possible to promote drug research from the individual/cellular level to the subcellular level, as well as give a new focus based on newly found organelle activities.
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Affiliation(s)
- Xintian Shao
- School of Life Sciences, Medical Science and Technology Innovation Center, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, Shandong 250117, PR China
| | - Caicai Meng
- School of Life Sciences, Medical Science and Technology Innovation Center, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, Shandong 250117, PR China
| | - Wenjing Song
- School of Life Sciences, Medical Science and Technology Innovation Center, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, Shandong 250117, PR China; School of Pharmaceutical Sciences & Institute of Materia Medica, National Key Laboratory of Advanced Drug Delivery System, Medical Science and Technology Innovation Center, Key Laboratory for Biotechnology Drugs of National Health Commission, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, Shandong 250117, PR China
| | - Tao Zhang
- Department of General Surgery, The First Affiliated Hospital of Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, Shandong Province 250014, PR China
| | - Qixin Chen
- School of Pharmaceutical Sciences & Institute of Materia Medica, National Key Laboratory of Advanced Drug Delivery System, Medical Science and Technology Innovation Center, Key Laboratory for Biotechnology Drugs of National Health Commission, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, Shandong 250117, PR China.
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16
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Yi M, Wang M, Xu Y, Cao Z, Ling Y, Zhang Z, Cao H. CRISPR-based m 6A modification and its potential applications in telomerase regulation. Front Cell Dev Biol 2023; 11:1200734. [PMID: 37519297 PMCID: PMC10382234 DOI: 10.3389/fcell.2023.1200734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Accepted: 06/27/2023] [Indexed: 08/01/2023] Open
Abstract
Telomerase determines cell lifespan by controlling chromosome stability and cell viability, m6A epigenetic modification plays an important role in the regulation of telomerase activity. Using CRISPR epigenome editing to analyze specific m6A modification sites in telomerase will provide an important tool for analyzing the molecular mechanism of m6A modification regulating telomerase activity. In this review, we clarified the relevant applications of CRISPR system, paid special attention to the regulation of m6A modification in stem cells and cancer cells based on CRISPR system, emphasized the regulation of m6A modification on telomerase activity, pointed out that m6A modification sites regulate telomerase activity, and discussed strategies based on telomerase activity and disease treatment, which are helpful to promote the research of anti-aging and tumor related diseases.
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Affiliation(s)
- Mingliang Yi
- Anhui Province Key Laboratory of Local Livestock and Poultry Genetic Resource Conservation and Bio-breeding, Anhui Agricultural University, Hefei, China
| | - Mingyue Wang
- Anhui Province Key Laboratory of Local Livestock and Poultry Genetic Resource Conservation and Bio-breeding, Anhui Agricultural University, Hefei, China
| | - Yongjie Xu
- Anhui Province Key Laboratory of Local Livestock and Poultry Genetic Resource Conservation and Bio-breeding, Anhui Agricultural University, Hefei, China
| | - Zhikun Cao
- Anhui Province Key Laboratory of Local Livestock and Poultry Genetic Resource Conservation and Bio-breeding, Anhui Agricultural University, Hefei, China
| | - Yinghui Ling
- Anhui Province Key Laboratory of Local Livestock and Poultry Genetic Resource Conservation and Bio-breeding, Anhui Agricultural University, Hefei, China
- College of Animal Science and Technology, Anhui Agricultural University, Hefei, China
| | - Zijun Zhang
- Anhui Province Key Laboratory of Local Livestock and Poultry Genetic Resource Conservation and Bio-breeding, Anhui Agricultural University, Hefei, China
- College of Animal Science and Technology, Anhui Agricultural University, Hefei, China
| | - Hongguo Cao
- Anhui Province Key Laboratory of Local Livestock and Poultry Genetic Resource Conservation and Bio-breeding, Anhui Agricultural University, Hefei, China
- College of Animal Science and Technology, Anhui Agricultural University, Hefei, China
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17
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Broadbent DG, Barnaba C, Perez GI, Schmidt JC. Quantitative analysis of autophagy reveals the role of ATG9 and ATG2 in autophagosome formation. J Cell Biol 2023; 222:e202210078. [PMID: 37115157 PMCID: PMC10148237 DOI: 10.1083/jcb.202210078] [Citation(s) in RCA: 25] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 02/03/2023] [Accepted: 03/17/2023] [Indexed: 04/29/2023] Open
Abstract
Autophagy is a catabolic pathway required for the recycling of cytoplasmic materials. To define the mechanisms underlying autophagy it is critical to quantitatively characterize the dynamic behavior of autophagy factors in living cells. Using a panel of cell lines expressing HaloTagged autophagy factors from their endogenous loci, we analyzed the abundance, single-molecule dynamics, and autophagosome association kinetics of autophagy proteins involved in autophagosome biogenesis. We demonstrate that autophagosome formation is inefficient and ATG2-mediated tethering to donor membranes is a key commitment step in autophagosome formation. Furthermore, our observations support the model that phagophores are initiated by the accumulation of autophagy factors on mobile ATG9 vesicles, and that the ULK1 complex and PI3-kinase form a positive feedback loop required for autophagosome formation. Finally, we demonstrate that the duration of autophagosome biogenesis is ∼110 s. In total, our work provides quantitative insight into autophagosome biogenesis and establishes an experimental framework to analyze autophagy in human cells.
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Affiliation(s)
- David G. Broadbent
- Institute for Quantitative Health Science and Engineering, Michigan State University, East Lansing, MI, USA
- College of Osteopathic Medicine, Michigan State University, East Lansing, MI, USA
- Department of Physiology, Michigan State University, East Lansing, MI, USA
| | - Carlo Barnaba
- Institute for Quantitative Health Science and Engineering, Michigan State University, East Lansing, MI, USA
| | - Gloria I. Perez
- Institute for Quantitative Health Science and Engineering, Michigan State University, East Lansing, MI, USA
| | - Jens C. Schmidt
- Institute for Quantitative Health Science and Engineering, Michigan State University, East Lansing, MI, USA
- Department of Obstetrics and Gynecology, Michigan State University, East Lansing, MI, USA
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18
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Wong-Dilworth L, Rodilla-Ramirez C, Fox E, Restel SD, Stockhammer A, Adarska P, Bottanelli F. STED imaging of endogenously tagged ARF GTPases reveals their distinct nanoscale localizations. J Cell Biol 2023; 222:e202205107. [PMID: 37102998 PMCID: PMC10140647 DOI: 10.1083/jcb.202205107] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 01/10/2023] [Accepted: 04/05/2023] [Indexed: 04/28/2023] Open
Abstract
ADP-ribosylation factor (ARF) GTPases are major regulators of cellular membrane homeostasis. High sequence similarity and multiple, possibly redundant functions of the five human ARFs make investigating their function a challenging task. To shed light on the roles of the different Golgi-localized ARF members in membrane trafficking, we generated CRISPR-Cas9 knockins (KIs) of type I (ARF1 and ARF3) and type II ARFs (ARF4 and ARF5) and mapped their nanoscale localization with stimulated emission depletion (STED) super-resolution microscopy. We find ARF1, ARF4, and ARF5 on segregated nanodomains on the cis-Golgi and ER-Golgi intermediate compartments (ERGIC), revealing distinct roles in COPI recruitment on early secretory membranes. Interestingly, ARF4 and ARF5 define Golgi-tethered ERGIC elements decorated by COPI and devoid of ARF1. Differential localization of ARF1 and ARF4 on peripheral ERGICs suggests the presence of functionally different classes of intermediate compartments that could regulate bi-directional transport between the ER and the Golgi. Furthermore, ARF1 and ARF3 localize to segregated nanodomains on the trans-Golgi network (TGN) and are found on TGN-derived post-Golgi tubules, strengthening the idea of distinct roles in post-Golgi sorting. This work provides the first map of the nanoscale organization of human ARF GTPases on cellular membranes and sets the stage to dissect their numerous cellular roles.
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Affiliation(s)
| | | | - Eleanor Fox
- Institut für Biochemie, Freie Universität Berlin, Berlin, Germany
| | | | | | - Petia Adarska
- Institut für Biochemie, Freie Universität Berlin, Berlin, Germany
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19
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Abstract
It has been known for decades that telomerase extends the 3' end of linear eukaryotic chromosomes and dictates the telomeric repeat sequence based on the template in its RNA. However, telomerase does not mitigate sequence loss at the 5' ends of chromosomes, which results from lagging strand DNA synthesis and nucleolytic processing. Therefore, a second enzyme is needed to keep telomeres intact: DNA polymerase α/Primase bound to Ctc1-Stn1-Ten1 (CST). CST-Polα/Primase maintains telomeres through a fill-in reaction that replenishes the lost sequences at the 5' ends. CST not only serves to maintain telomeres but also determines their length by keeping telomerase from overelongating telomeres. Here we discuss recent data on the evolution, structure, function, and recruitment of mammalian CST-Polα/Primase, highlighting the role of this complex and telomere length control in human disease.
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Affiliation(s)
- Sarah W Cai
- Laboratory for Cell Biology and Genetics, The Rockefeller University, New York, New York 10065, USA
| | - Titia de Lange
- Laboratory for Cell Biology and Genetics, The Rockefeller University, New York, New York 10065, USA
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20
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Klump BM, Perez GI, Patrick EM, Adams-Boone K, Cohen SB, Han L, Yu K, Schmidt JC. TCAB1 prevents nucleolar accumulation of the telomerase RNA to facilitate telomerase assembly. Cell Rep 2023; 42:112577. [PMID: 37267110 PMCID: PMC10569210 DOI: 10.1016/j.celrep.2023.112577] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2023] [Revised: 03/27/2023] [Accepted: 05/12/2023] [Indexed: 06/04/2023] Open
Abstract
Localization of a variety of RNAs to non-membrane-bound cellular compartments such as nucleoli and Cajal bodies is critical for their stability and function. The molecular mechanisms that underly the recruitment and exclusion of RNAs from these phase-separated organelles is incompletely understood. Telomerase is a ribonucleoprotein composed of the reverse transcriptase protein telomerase reverse transcriptase (TERT), the telomerase RNA (TR), and several auxiliary proteins, including TCAB1. Here we show that in the absence of TCAB1, a large fraction of TR is tightly bound to the nucleolus, while TERT is largely excluded from the nucleolus, reducing telomerase assembly. This suggests that nuclear compartmentalization by the non-membrane-bound nucleolus counteracts telomerase assembly, and TCAB1 is required to retain TR in the nucleoplasm. Our work provides insight into the mechanism and functional consequences of RNA recruitment to organelles formed by phase separation and demonstrates that TCAB1 plays an important role in telomerase assembly.
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Affiliation(s)
- Basma M Klump
- Institute for Quantitative Health Sciences and Engineering, Michigan State University, East Lansing, MI, USA; College of Osteopathic Medicine, Michigan State University, East Lansing, MI, USA; Cellular and Molecular Biology Graduate Program, College of Natural Sciences, Michigan State University, East Lansing, MI, USA
| | - Gloria I Perez
- Institute for Quantitative Health Sciences and Engineering, Michigan State University, East Lansing, MI, USA
| | - Eric M Patrick
- Institute for Quantitative Health Sciences and Engineering, Michigan State University, East Lansing, MI, USA
| | - Kate Adams-Boone
- Institute for Quantitative Health Sciences and Engineering, Michigan State University, East Lansing, MI, USA
| | - Scott B Cohen
- Children's Medical Research Institute and University of Sydney, Westmead, NSW 2145, Australia
| | - Li Han
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA
| | - Kefei Yu
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA
| | - Jens C Schmidt
- Institute for Quantitative Health Sciences and Engineering, Michigan State University, East Lansing, MI, USA; Department of Obstetrics, Gynecology, and Reproductive Biology, Michigan State University, East Lansing, MI, USA.
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21
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Padmanaban S, Tesmer VM, Nandakumar J. Interaction hub critical for telomerase recruitment and primer-template handling for catalysis. Life Sci Alliance 2023; 6:e202201727. [PMID: 36963832 PMCID: PMC10055720 DOI: 10.26508/lsa.202201727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Revised: 03/14/2023] [Accepted: 03/15/2023] [Indexed: 03/26/2023] Open
Abstract
Telomerase processively adds telomeric DNA repeats to chromosome ends using catalytic protein subunit TERT and a template on its RNA subunit TR. Mammalian telomerase is recruited to telomeres by the TEL patch and NOB regions of shelterin component TPP1. Recent cryo-EM structures of human telomerase reveal that a composite TERT TEN-(IFD-TRAP) domain interacts with TPP1. Here, we generate TERT mutants to demonstrate that a three-way TEN-(IFD-TRAP)-TPP1 interaction is critical for telomerase recruitment to telomeres and processive telomere repeat addition. Single mutations of IFD-TRAP at its interface with TR or the DNA primer impair telomerase catalysis. We further reveal the importance of TERT motif 3N and TEN domain loop 99FGF101 in telomerase action. Finally, we demonstrate that TPP1 TEL patch loop residue F172, which undergoes a structural rearrangement to bind telomerase, contributes to the human-mouse species specificity of the telomerase-TPP1 interaction. Our study provides insights into the multiple functions of TERT IFD-TRAP, reveals novel TERT and TPP1 elements critical for function, and helps explain how TPP1 binding licenses robust telomerase action at natural chromosome ends.
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Affiliation(s)
- Shilpa Padmanaban
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Valerie M Tesmer
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Jayakrishnan Nandakumar
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
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22
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Schaich MA, Schnable BL, Kumar N, Roginskaya V, Jakielski R, Urban R, Zhong Z, Kad NM, Van Houten B. Single-molecule analysis of DNA-binding proteins from nuclear extracts (SMADNE). Nucleic Acids Res 2023; 51:e39. [PMID: 36861323 PMCID: PMC10123111 DOI: 10.1093/nar/gkad095] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2022] [Revised: 01/19/2023] [Accepted: 02/08/2023] [Indexed: 03/03/2023] Open
Abstract
Single-molecule characterization of protein-DNA dynamics provides unprecedented mechanistic details about numerous nuclear processes. Here, we describe a new method that rapidly generates single-molecule information with fluorescently tagged proteins isolated from nuclear extracts of human cells. We demonstrated the wide applicability of this novel technique on undamaged DNA and three forms of DNA damage using seven native DNA repair proteins and two structural variants, including: poly(ADP-ribose) polymerase (PARP1), heterodimeric ultraviolet-damaged DNA-binding protein (UV-DDB), and 8-oxoguanine glycosylase 1 (OGG1). We found that PARP1 binding to DNA nicks is altered by tension, and that UV-DDB did not act as an obligate heterodimer of DDB1 and DDB2 on UV-irradiated DNA. UV-DDB bound to UV photoproducts with an average lifetime of 39 seconds (corrected for photobleaching, τc), whereas binding lifetimes to 8-oxoG adducts were < 1 second. Catalytically inactive OGG1 variant K249Q bound oxidative damage 23-fold longer than WT OGG1, at 47 and 2.0 s, respectively. By measuring three fluorescent colors simultaneously, we also characterized the assembly and disassembly kinetics of UV-DDB and OGG1 complexes on DNA. Hence, the SMADNE technique represents a novel, scalable, and universal method to obtain single-molecule mechanistic insights into key protein-DNA interactions in an environment containing physiologically-relevant nuclear proteins.
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Affiliation(s)
- Matthew A Schaich
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- UPMC-Hillman Cancer Center, Pittsburgh, PA, 15232, USA
| | - Brittani L Schnable
- UPMC-Hillman Cancer Center, Pittsburgh, PA, 15232, USA
- Molecular Biophysics and Structural Biology Program, University of Pittsburgh, Pittsburgh, PA, USA
| | - Namrata Kumar
- UPMC-Hillman Cancer Center, Pittsburgh, PA, 15232, USA
- Molecular Genetics and Developmental Biology Graduate Program, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | | | - Rachel C Jakielski
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- UPMC-Hillman Cancer Center, Pittsburgh, PA, 15232, USA
| | - Roman Urban
- School of Biosciences, University of Kent, Kent, UK
| | - Zhou Zhong
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- UPMC-Hillman Cancer Center, Pittsburgh, PA, 15232, USA
- LUMICKS, Waltham, MA, USA
| | - Neil M Kad
- School of Biosciences, University of Kent, Kent, UK
| | - Bennett Van Houten
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- UPMC-Hillman Cancer Center, Pittsburgh, PA, 15232, USA
- Molecular Genetics and Developmental Biology Graduate Program, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Molecular Biophysics and Structural Biology Program, University of Pittsburgh, Pittsburgh, PA, USA
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23
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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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24
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Chung YC, Bisht M, Thuma J, Tu LC. Single-chromosome dynamics reveals locus-dependent dynamics and chromosome territory orientation. J Cell Sci 2023; 136:jcs260137. [PMID: 36718642 PMCID: PMC10022681 DOI: 10.1242/jcs.260137] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2022] [Accepted: 01/19/2023] [Indexed: 02/01/2023] Open
Abstract
Dynamic chromatin organization instantly influences DNA accessibility through modulating local macromolecular density and interactions, driving changes in transcription activities. Chromatin dynamics have been reported to be locally confined but contribute to coherent chromatin motion across the entire nucleus. However, the regulation of dynamics, nuclear orientation and compaction of subregions along a single chromosome are not well-understood. We used CRISPR-based real-time single-particle tracking and polymer models to characterize the dynamics of specific genomic loci and determine compaction levels of large human chromosomal domains. Our studies showed that chromosome compaction changed during interphase and that compactions of two arms on chromosome 19 were different. The dynamics of genomic loci were subdiffusive and dependent on chromosome regions and transcription states. Surprisingly, the correlation between locus-dependent nuclear localization and mobility was negligible. Strong tethering interactions detected at the pericentromeric region implies local condensation or associations with organelles within local nuclear microenvironments, such as chromatin-nuclear body association. Based on our findings, we propose a 'guided radial model' for the nuclear orientation of the long arm of chromosome 19.
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Affiliation(s)
- Yu-Chieh Chung
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH 43210, USA
| | - Madhoolika Bisht
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH 43210, USA
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, USA
| | - Jenna Thuma
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH 43210, USA
- Interdisciplinary Biophysics Graduate Program, The Ohio State University, Columbus, OH 43210, USA
| | - Li-Chun Tu
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH 43210, USA
- Interdisciplinary Biophysics Graduate Program, The Ohio State University, Columbus, OH 43210, USA
- Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA
- The Ohio State University Comprehensive Cancer Center, The Ohio State University, Columbus, OH 43210, USA
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25
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Wen J, Zhong X, Gao C, Yang M, Tang M, Yuan Z, Wang Q, Xu L, Ma Q, Guo X, Fang L. TPP1 Inhibits DNA Damage Response and Chemosensitivity in Esophageal Cancer. Crit Rev Eukaryot Gene Expr 2023; 33:77-91. [PMID: 37606165 DOI: 10.1615/critreveukaryotgeneexpr.2023048720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/23/2023]
Abstract
TPP1, as one of the telomere-protective protein complex, functions to maintain telomere stability. In this study, we found that TPP1 was significantly upregulated in esophageal cancer (EC). We found that the proliferation and migration ability were significantly inhibited, while the results of flow cytometry assay indicated that the growth was hindered in the G1 phase after TPP1 knockdown. However, the proliferative viability and migratory ability were reversed after TPP1 overexpression in EC cells. Then, we found a significant increase in β-galactosidase positivity following TPP1 knockdown and the opposite following TPP1 overexpression in EC cells. Furthermore, TPP1 knockdown increased DNA damage and upregulated expression of the γ-H2AXS139 in the cell nucleus. Correspondingly, DNA damage was reversed after TPP1 overexpression in EC cells. Similarly, we found that the expression of ATM/ATR pathway proteins were upregulated after TPP1 knockdown, while the expression of the above proteins was downregulated after TPP1 overexpression in EC cells. TPP1 knockdown significantly inhibited the growth of transplanted tumors and upregulated the expression of ATM/ATR pathway proteins in transplanted tissues, whereas TPP1 overexpression significantly promoted their proliferation and downregulated the expression of the above proteins in vivo. Strikingly, we found that TPP1 could reduce the chemosensitivity of EC cells to cisplatin, which may have a potential link to clinical chemoresistance. In conclusion, TPP1 regulates the DNA damage response through the ATM/ATR-p53 signaling pathway and chemoresistance and may be a new target for improving the efficacy of chemotherapy in the treatment of EC.
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Affiliation(s)
- Jilin Wen
- Department of Laboratory Medicine, North Sichuan Medical College, Nanchong 637000, China
| | - Xiaowu Zhong
- Department of Laboratory Medicine, Affiliated Hospital of North Sichuan Medical College, Nanchong, Sichuan 637000, P.R. China; Department of Laboratory Medicine, North Sichuan Medical College, Nanchong, Sichuan 637000, P.R. China; Translational Medicine Research Center, North Sichuan Medical College, Nanchong, Sichuan 637000, P.R. China
| | - Chuanli Gao
- Department of Laboratory Medicine, North Sichuan Medical College, Nanchong 637000, China
| | - Miyuan Yang
- Department of Laboratory Medicine, North Sichuan Medical College, Nanchong 637000, China
| | - Maoju Tang
- Department of Laboratory Medicine, North Sichuan Medical College, Nanchong 637000, China
| | - Zichun Yuan
- Department of Laboratory Medicine, Affiliated Hospital of North Sichuan Medical College, Nanchong, Sichuan 637000, P.R. China; Department of Laboratory Medicine, North Sichuan Medical College, Nanchong, Sichuan 637000, P.R. China
| | - Qin Wang
- Department of Laboratory Medicine, North Sichuan Medical College, Nanchong 637000, China
| | - Lei Xu
- Translational Medicine Research Center, North Sichuan Medical College, Nanchong, Sichuan 637000, P.R. China
| | - Qiang Ma
- Department of Laboratory Medicine, Affiliated Hospital of North Sichuan Medical College, Nanchong, Sichuan 637000, P.R. China; Department of Laboratory Medicine, North Sichuan Medical College, Nanchong, Sichuan 637000, P.R. China; Translational Medicine Research Center, North Sichuan Medical College, Nanchong, Sichuan 637000, P.R. China
| | - Xiaolan Guo
- Department of Laboratory Medicine, Affiliated Hospital of North Sichuan Medical College, Nanchong, Sichuan 637000, P.R. China; Department of Laboratory Medicine, North Sichuan Medical College, Nanchong, Sichuan 637000, P.R. China; Translational Medicine Research Center, North Sichuan Medical College, Nanchong, Sichuan 637000, P.R. China
| | - Li Fang
- Department of Laboratory Medicine, North Sichuan Medical College, Nanchong 637000, China; Department of Clinical Laboratory, Affiliated Hospital of North Sichuan Medical College, Nanchong 637000, China
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26
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Zhang Q, Yuan ZZ, Zhang X, Zhang Y, Zou X, Ma F, Zhang CY. Entropy-Driven Self-Assembly of Single Quantum Dot Sensor for Catalytic Imaging of Telomerase in Living Cells. Anal Chem 2022; 94:18092-18098. [PMID: 36519804 DOI: 10.1021/acs.analchem.2c04747] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Telomerase is a highly valuable cancer diagnosis biomarker and a promising cancer therapy target. So far, most telomerase assays are limited by the involvement of tedious procedures, multiple enzymes, and complicated reaction schemes. Sensitive monitoring of low-abundant telomerase in living cells remains a challenge. Herein, we demonstrate an entropy-driven catalytic assembly of quantum dot (QD) sensors for accurate detection and imaging of telomerase activity in living cells. In this sensor, target telomerase specifically catalyzes extension of telomerase primer, and the extended primer subsequently acts as a catalyst to continuously initiate entropy-driven catalytic reaction, generating a large number of fluorophore- and biotin-labeled DNAs that can be self-assembled on the QD surface to induce an efficient Föster resonance energy transfer signal. The proposed sensor requires a single step for both recognition and amplification of the telomerase signal, eliminating the use of either protein enzymes or laborious procedures. Taking advantage of the inherent superiority of single-molecule fluorescence detection and high amplification efficiency of the entropy-driven reaction, this sensor demonstrates single-cell sensitivity for the in vitro assay. Moreover, it is capable of screening the telomerase inhibitor, discriminating different tumor cells from normal ones, and even real-time imaging telomerase in living cells, providing a novel platform for telomerase-associated cancer diagnosis and drug screening.
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Affiliation(s)
- Qian Zhang
- College of Chemistry, Chemical Engineering and Materials Science, Shandong Normal University, Jinan250014, China
| | - Zhen-Zhen Yuan
- College of Chemistry, Chemical Engineering and Materials Science, Shandong Normal University, Jinan250014, China
| | - Xinyi Zhang
- School of Chemistry and Chemical Engineering, Guangdong Pharmaceutical University, Zhongshan528458, China
| | - Yan Zhang
- College of Chemistry, Chemical Engineering and Materials Science, Shandong Normal University, Jinan250014, China
| | - Xiaoran Zou
- College of Chemistry, Chemical Engineering and Materials Science, Shandong Normal University, Jinan250014, China
| | - Fei Ma
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing211189, China
| | - Chun-Yang Zhang
- College of Chemistry, Chemical Engineering and Materials Science, Shandong Normal University, Jinan250014, China
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27
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Mahadevan J, Jha A, Rudolph J, Bowerman S, Narducci D, Hansen AS, Luger K. Dynamics of endogenous PARP1 and PARP2 during DNA damage revealed by live-cell single-molecule imaging. iScience 2022; 26:105779. [PMID: 36594010 PMCID: PMC9804145 DOI: 10.1016/j.isci.2022.105779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 08/16/2022] [Accepted: 12/07/2022] [Indexed: 12/13/2022] Open
Abstract
PARP1 contributes to genome architecture and DNA damage repair through its dynamic association with chromatin. PARP1 and PARP2 (PARP1/2) recognize damaged DNA and recruit the DNA repair machinery. Using single-molecule microscopy in live cells, we monitored the movement of PARP1/2 on undamaged and damaged chromatin. We identify two classes of freely diffusing PARP1/2 and two classes of bound PARP1/2. The majority (>60%) of PARP1/2 diffuse freely in both undamaged and damaged nuclei and in the presence of inhibitors of PARP1/2 used for cancer therapy (PARPi). Laser-induced DNA damage results in a small fraction of slowly diffusing PARP1 and PARP2 to become transiently bound. Treatment of cells with PARPi in the presence of DNA damage causes subtle changes in the dynamics of bound PARP1/2, but not the high levels of PARP1/2 trapping seen previously. Our results imply that next-generation PARPi could specifically target the small fraction of DNA-bound PARP1/2.
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Affiliation(s)
- Jyothi Mahadevan
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Asmita Jha
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Johannes Rudolph
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Samuel Bowerman
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80309, USA,Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Domenic Narducci
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Anders S. Hansen
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Karolin Luger
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80309, USA,Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO 80309, USA,Corresponding author
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28
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Smith S, Hoelzl F, Zahn S, Criscuolo F. Telomerase activity in ecological studies: What are its consequences for individual physiology and is there evidence for effects and trade-offs in wild populations. Mol Ecol 2022; 31:6239-6251. [PMID: 34664335 PMCID: PMC9788021 DOI: 10.1111/mec.16233] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 09/10/2021] [Accepted: 09/24/2021] [Indexed: 02/02/2023]
Abstract
Increasing evidence at the cellular level is helping to provide proximate explanations for the balance between investment in growth, reproduction and somatic maintenance in wild populations. Studies of telomere dynamics have informed researchers about the loss and gain of telomere length both on a seasonal scale and across the lifespan of individuals. In addition, telomere length and telomere rate of loss seems to have evolved differently among taxonomic groups, and relate differently to organismal diversity of lifespan. So far, the mechanisms behind telomere maintenance remain elusive, although many studies have inferred a role for telomerase, an enzyme/RNA complex known to induce telomere elongation from laboratory studies. Exciting further work is also emerging that suggests telomerase (and/or its individual component parts) has a role in fitness that goes beyond the maintenance of telomere length. Here, we review the literature on telomerase biology and examine the evidence from ecological studies for the timing and extent of telomerase activation in relation to life history events associated with telomere maintenance. We suggest that the underlying mechanism is more complicated than originally anticipated, possibly involves several complimentary pathways, and is probably associated with high energetic costs. Potential pathways for future research are numerous and we outline what we see as the most promising prospects to expand our understanding of individual differences in immunity or reproduction efficiency.
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Affiliation(s)
- Steve Smith
- Konrad Lorenz Institute of EthologyUniversity of Veterinary Medicine, ViennaViennaAustria
| | - Franz Hoelzl
- Konrad Lorenz Institute of EthologyUniversity of Veterinary Medicine, ViennaViennaAustria
| | - Sandrine Zahn
- Department of Physiology, Evolution and BehaviourInstitut Pluridisciplinaire Hubert CurienCNRSUniversity of StrasbourgStrasbourgFrance
| | - François Criscuolo
- Department of Physiology, Evolution and BehaviourInstitut Pluridisciplinaire Hubert CurienCNRSUniversity of StrasbourgStrasbourgFrance
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29
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Kuhn T, Landge AN, Mörsdorf D, Coßmann J, Gerstenecker J, Čapek D, Müller P, Gebhardt JCM. Single-molecule tracking of Nodal and Lefty in live zebrafish embryos supports hindered diffusion model. Nat Commun 2022; 13:6101. [PMID: 36243734 PMCID: PMC9569377 DOI: 10.1038/s41467-022-33704-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Accepted: 09/28/2022] [Indexed: 12/24/2022] Open
Abstract
The hindered diffusion model postulates that the movement of a signaling molecule through an embryo is affected by tissue geometry and binding-mediated hindrance, but these effects have not been directly demonstrated in vivo. Here, we visualize extracellular movement and binding of individual molecules of the activator-inhibitor signaling pair Nodal and Lefty in live developing zebrafish embryos using reflected light-sheet microscopy. We observe that diffusion coefficients of molecules are high in extracellular cavities, whereas mobility is reduced and bound fractions are high within cell-cell interfaces. Counterintuitively, molecules nevertheless accumulate in cavities, which we attribute to the geometry of the extracellular space by agent-based simulations. We further find that Nodal has a larger bound fraction than Lefty and shows a binding time of tens of seconds. Together, our measurements and simulations provide direct support for the hindered diffusion model and yield insights into the nanometer-to-micrometer-scale mechanisms that lead to macroscopic signal dispersal.
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Affiliation(s)
- Timo Kuhn
- grid.6582.90000 0004 1936 9748Institute of Biophysics, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany
| | - Amit N. Landge
- grid.9811.10000 0001 0658 7699University of Konstanz, Universitätsstraße 10, 78464 Konstanz, Germany
| | - David Mörsdorf
- grid.418026.90000 0004 0492 0357Friedrich Miescher Laboratory of the Max Planck Society, Max-Planck-Ring 9, 72076 Tübingen, Germany ,grid.10420.370000 0001 2286 1424University of Vienna, Department of Neurosciences and Developmental Biology, Djerassiplatz 1, 1030 Vienna, Austria
| | - Jonas Coßmann
- grid.6582.90000 0004 1936 9748Institute of Biophysics, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany
| | - Johanna Gerstenecker
- grid.6582.90000 0004 1936 9748Institute of Biophysics, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany
| | - Daniel Čapek
- grid.9811.10000 0001 0658 7699University of Konstanz, Universitätsstraße 10, 78464 Konstanz, Germany
| | - Patrick Müller
- grid.9811.10000 0001 0658 7699University of Konstanz, Universitätsstraße 10, 78464 Konstanz, Germany ,grid.418026.90000 0004 0492 0357Friedrich Miescher Laboratory of the Max Planck Society, Max-Planck-Ring 9, 72076 Tübingen, Germany
| | - J. Christof M. Gebhardt
- grid.6582.90000 0004 1936 9748Institute of Biophysics, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany
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30
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Gao J, Pickett HA. Targeting telomeres: advances in telomere maintenance mechanism-specific cancer therapies. Nat Rev Cancer 2022; 22:515-532. [PMID: 35790854 DOI: 10.1038/s41568-022-00490-1] [Citation(s) in RCA: 72] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/25/2022] [Indexed: 12/31/2022]
Abstract
Cancer cells establish replicative immortality by activating a telomere-maintenance mechanism (TMM), be it telomerase or the alternative lengthening of telomeres (ALT) pathway. Targeting telomere maintenance represents an intriguing opportunity to treat the vast majority of all cancer types. Whilst telomerase inhibitors have historically been heralded as promising anticancer agents, the reality has been more challenging, and there are currently no therapeutic options for cancer types that use ALT despite their aggressive nature and poor prognosis. In this Review, we discuss the mechanistic differences between telomere maintenance by telomerase and ALT, the current methods used to detect each mechanism, the utility of these tests for clinical diagnosis, and recent developments in the therapeutic strategies being employed to target both telomerase and ALT. We present notable developments in repurposing established therapeutic agents and new avenues that are emerging to target cancer types according to which TMM they employ. These opportunities extend beyond inhibition of telomere maintenance, by finding and exploiting inherent weaknesses in the telomeres themselves to trigger rapid cellular effects that lead to cell death.
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Affiliation(s)
- Jixuan Gao
- Telomere Length Regulation Unit, Children's Medical Research Institute, Faculty of Medicine and Health, University of Sydney, Westmead, NSW, Australia
| | - Hilda A Pickett
- Telomere Length Regulation Unit, Children's Medical Research Institute, Faculty of Medicine and Health, University of Sydney, Westmead, NSW, Australia.
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31
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Wang J, Liu X, Xue W, Wei Y, Xu Z. Highly sensitive monitoring of telomerase activity in living cells based on rapidly triggered cascade amplification reaction. Biosens Bioelectron 2022; 216:114645. [PMID: 36029663 DOI: 10.1016/j.bios.2022.114645] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 08/04/2022] [Accepted: 08/16/2022] [Indexed: 11/25/2022]
Abstract
Telomerase is an important potential biomarker for the study of tumor progression. Herein, we designed a cascade-amplification-reaction-based nanoprobe for intracellular telomerase detection based on the integration of rolling circle amplification (RCA) and catalytic hairpin assembly (CHA) onto MnO2 nanosheets. Firstly, MnO2 nanosheets rapidly delivered and released signal amplification units into cells, and very short telomerase extension products formed RCA circular templates and initiated the exponential RCA, producing enriched telomere sequence amplification products. Then the amplification products specifically triggered the CHA process and numerous H1/H2 complexes were formed, realizing the exponential amplification of fluorescence signals. The detection limit is as low as 1 LoVo cell for telomerase activity in cell extract. We further designed a microfluidic chip with six independent cell culture regions for in situ fluorescence imaging. Simultaneous detection of six types of cells was realized on the chip, and only 1-2 μL of cell suspension and reagents are needed. Our detection method features faster response speed and stronger fluorescence signal. Telomerase in living cells showed strong fluorescence signal within 1.5 h, and tumor cells were effectively distinguished from normal cells. Telomerase activities of different types of tumor cells and activity changes were both monitored conveniently. These results demonstrate that this method holds the potential for the sensitive detection of low abundance biomarkers in living cells, and will contribute to cancer diagnosis, cancer treatment and telomerase-related drug screening.
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Affiliation(s)
- Jie Wang
- Research Center for Analytical Sciences, Northeastern University, Shenyang, 110819, PR China
| | - Xiaopeng Liu
- Research Center for Analytical Sciences, Northeastern University, Shenyang, 110819, PR China
| | - Wanyi Xue
- Research Center for Analytical Sciences, Northeastern University, Shenyang, 110819, PR China
| | - Yunyun Wei
- Research Center for Analytical Sciences, Northeastern University, Shenyang, 110819, PR China
| | - Zhangrun Xu
- Research Center for Analytical Sciences, Northeastern University, Shenyang, 110819, PR China.
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32
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Mehra D, Adhikari S, Banerjee C, Puchner EM. Characterizing locus specific chromatin structure and dynamics with correlative conventional and super-resolution imaging in living cells. Nucleic Acids Res 2022; 50:e78. [PMID: 35524554 PMCID: PMC9303368 DOI: 10.1093/nar/gkac314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 04/08/2022] [Accepted: 05/02/2022] [Indexed: 11/23/2022] Open
Abstract
The dynamic rearrangement of chromatin is critical for gene regulation, but mapping both the spatial organization of chromatin and its dynamics remains a challenge. Many structural conformations are too small to be resolved via conventional fluorescence microscopy and the long acquisition time of super-resolution photoactivated localization microscopy (PALM) precludes the structural characterization of chromatin below the optical diffraction limit in living cells due to chromatin motion. Here we develop a correlative conventional fluorescence and PALM imaging approach to quantitatively map time-averaged chromatin structure and dynamics below the optical diffraction limit in living cells. By assigning localizations to a locus as it moves, we reliably discriminate between bound and unbound dCas9 molecules, whose mobilities overlap. Our approach accounts for changes in DNA mobility and relates local chromatin motion to larger scale domain movement. In our experimental system, we show that compacted telomeres move faster and have a higher density of bound dCas9 molecules, but the relative motion of those molecules is more restricted than in less compacted telomeres. Correlative conventional and PALM imaging therefore improves the ability to analyze the mobility and time-averaged nanoscopic structural features of locus specific chromatin with single molecule sensitivity and yields unprecedented insights across length and time scales.
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Affiliation(s)
- Dushyant Mehra
- School of Physics and Astronomy, University of Minnesota, Minneapolis MN, USA
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester MN, USA
| | - Santosh Adhikari
- School of Physics and Astronomy, University of Minnesota, Minneapolis MN, USA
| | - Chiranjib Banerjee
- School of Physics and Astronomy, University of Minnesota, Minneapolis MN, USA
| | - Elias M Puchner
- School of Physics and Astronomy, University of Minnesota, Minneapolis MN, USA
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33
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Liu X, Zhang L, Lu L, Jiang W, Zhang N. A primer extension activating 3D DNAzyme walker for in situ imaging and sensitive detection of telomerase activity. Analyst 2022; 147:1968-1975. [PMID: 35416808 DOI: 10.1039/d2an00142j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Acquiring information on telomerase activity at multiple levels contributes to a better understanding of its role in various physiological and pathological processes. Herein, a primer extension activating 3D DNAzyme walker is developed for in situ imaging and sensitive detection of telomerase activity. This walker is constructed via co-modifying specially designed hairpin structured walking strands and track strands on a gold nanoparticle (AuNP). The walking strand contains a pre-blocked DNAzyme sequence and a telomerase primer hybridized to its root. The track strand embeds at an RNA cleavage site and is labeled with the FAM group. After this walker is taken up by cells, the telomerase primer is extended under the action of endogenous telomerase to liberate DNAzyme. The liberated DNAzyme cuts track strands in the presence of the cofactor Mn2+ to drive the walker's processive operation, resulting in an enhanced fluorescence recovery of the AuNP-quenched FAM fluorophore. In situ imaging of telomerase activity in three different cell lines (MCF-7 cells, HeLa cells and HL-7702 cells) was well implemented. The discrimination of cancer cells from normal cells and the screening of telomerase inhibitors have been achieved. The sensitive detection of telomerase activity in HeLa cell lysate has also been realized with a detection limit of 10 cells. This walker performed a new approach for monitoring telomerase activity from different levels, providing a potential tool for clinical diagnosis, prognostic evaluation and drug screening.
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Affiliation(s)
- Xiaoting Liu
- Research Center of Basic Medicine, Breast Center, Jinan Central Hospital, Cheeloo College of Medicine, Shandong University, 250013, Jinan, PR China. .,School of Chemistry and Chemical Engineering, Shandong University, 250100, Jinan, PR China
| | - Liyan Zhang
- School of Chemistry and Chemical Engineering, Shandong University, 250100, Jinan, PR China
| | - Ling Lu
- Research Center of Basic Medicine, Breast Center, Jinan Central Hospital, Cheeloo College of Medicine, Shandong University, 250013, Jinan, PR China.
| | - Wei Jiang
- School of Chemistry and Chemical Engineering, Shandong University, 250100, Jinan, PR China
| | - Nan Zhang
- Research Center of Basic Medicine, Breast Center, Jinan Central Hospital, Cheeloo College of Medicine, Shandong University, 250013, Jinan, PR China.
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34
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Liu B, He Y, Wang Y, Song H, Zhou ZH, Feigon J. Structure of active human telomerase with telomere shelterin protein TPP1. Nature 2022; 604:578-583. [PMID: 35418675 PMCID: PMC9912816 DOI: 10.1038/s41586-022-04582-8] [Citation(s) in RCA: 44] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 02/23/2022] [Indexed: 12/13/2022]
Abstract
Human telomerase is a RNA-protein complex that extends the 3' end of linear chromosomes by synthesizing multiple copies of the telomeric repeat TTAGGG1. Its activity is a determinant of cancer progression, stem cell renewal and cellular aging2-5. Telomerase is recruited to telomeres and activated for telomere repeat synthesis by the telomere shelterin protein TPP16,7. Human telomerase has a bilobal structure with a catalytic core ribonuclear protein and a H and ACA box ribonuclear protein8,9. Here we report cryo-electron microscopy structures of human telomerase catalytic core of telomerase reverse transcriptase (TERT) and telomerase RNA (TER (also known as hTR)), and of telomerase with the shelterin protein TPP1. TPP1 forms a structured interface with the TERT-unique telomerase essential N-terminal domain (TEN) and the telomerase RAP motif (TRAP) that are unique to TERT, and conformational dynamics of TEN-TRAP are damped upon TPP1 binding, defining the requirements for recruitment and activation. The structures further reveal that the elements of TERT and TER that are involved in template and telomeric DNA handling-including the TEN domain and the TRAP-thumb helix channel-are largely structurally homologous to those in Tetrahymena telomerase10, and provide unique insights into the mechanism of telomerase activity. The binding site of the telomerase inhibitor BIBR153211,12 overlaps a critical interaction between the TER pseudoknot and the TERT thumb domain. Numerous mutations leading to telomeropathies13,14 are located at the TERT-TER and TEN-TRAP-TPP1 interfaces, highlighting the importance of TER-TERT and TPP1 interactions for telomerase activity, recruitment and as drug targets.
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Affiliation(s)
- Baocheng Liu
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA, USA
| | - Yao He
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA, USA
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, USA
| | - Yaqiang Wang
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA, USA
| | - He Song
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA, USA
| | - Z Hong Zhou
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, USA
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA, USA
| | - Juli Feigon
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA, USA.
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CRISPR/Cas: A New Tool in the Research of Telomeres and Telomerase as Well as a Novel Form of Cancer Therapy. Int J Mol Sci 2022; 23:ijms23063002. [PMID: 35328421 PMCID: PMC8953708 DOI: 10.3390/ijms23063002] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 02/28/2022] [Accepted: 03/08/2022] [Indexed: 02/01/2023] Open
Abstract
Due to their close connection with senescence, aging, and disease, telomeres and telomerase provide a unique and vital research route for boosting longevity and health span. Despite significant advances during the last three decades, earlier studies into these two biological players were impeded by the difficulty of achieving real-time changes inside living cells. As a result of the clustered regularly interspaced short palindromic repeats (CRISPR)-associated system’s (Cas) method, targeted genetic studies are now underway to change telomerase, the genes that govern it as well as telomeres. This review will discuss studies that have utilized CRISPR-related technologies to target and modify genes relevant to telomeres and telomerase as well as to develop targeted anti-cancer therapies. These studies greatly improve our knowledge and understanding of cellular and molecular mechanisms that underlie cancer development and aging.
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Hong X, Wang L, Zhang K, Liu J, Liu JP. Molecular Mechanisms of Alveolar Epithelial Stem Cell Senescence and Senescence-Associated Differentiation Disorders in Pulmonary Fibrosis. Cells 2022; 11:877. [PMID: 35269498 PMCID: PMC8909789 DOI: 10.3390/cells11050877] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 03/01/2022] [Accepted: 03/02/2022] [Indexed: 02/04/2023] Open
Abstract
Pulmonary senescence is accelerated by unresolved DNA damage response, underpinning susceptibility to pulmonary fibrosis. Recently it was reported that the SARS-Cov-2 viral infection induces acute pulmonary epithelial senescence followed by fibrosis, although the mechanism remains unclear. Here, we examine roles of alveolar epithelial stem cell senescence and senescence-associated differentiation disorders in pulmonary fibrosis, exploring the mechanisms mediating and preventing pulmonary fibrogenic crisis. Notably, the TGF-β signalling pathway mediates alveolar epithelial stem cell senescence by mechanisms involving suppression of the telomerase reverse transcriptase gene in pulmonary fibrosis. Alternatively, telomere uncapping caused by stress-induced telomeric shelterin protein TPP1 degradation mediates DNA damage response, pulmonary senescence and fibrosis. However, targeted intervention of cellular senescence disrupts pulmonary remodelling and fibrosis by clearing senescent cells using senolytics or preventing senescence using telomere dysfunction inhibitor (TELODIN). Studies indicate that the development of senescence-associated differentiation disorders is reprogrammable and reversible by inhibiting stem cell replicative senescence in pulmonary fibrosis, providing a framework for targeted intervention of the molecular mechanisms of alveolar stem cell senescence and pulmonary fibrosis. Abbreviations: DPS, developmental programmed senescence; IPF, idiopathic pulmonary fibrosis; OIS, oncogene-induced replicative senescence; SADD, senescence-associated differentiation disorder; SALI, senescence-associated low-grade inflammation; SIPS, stress-induced premature senescence; TERC, telomerase RNA component; TERT, telomerase reverse transcriptase; TIFs, telomere dysfunction-induced foci; TIS, therapy-induced senescence; VIS, virus-induced senescence.
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Affiliation(s)
- Xiaojing Hong
- Institute of Ageing Research, Hangzhou Normal University School of Medicine, Hangzhou 311121, China; (X.H.); (L.W.); (K.Z.); (J.L.)
| | - Lihui Wang
- Institute of Ageing Research, Hangzhou Normal University School of Medicine, Hangzhou 311121, China; (X.H.); (L.W.); (K.Z.); (J.L.)
| | - Kexiong Zhang
- Institute of Ageing Research, Hangzhou Normal University School of Medicine, Hangzhou 311121, China; (X.H.); (L.W.); (K.Z.); (J.L.)
| | - Jun Liu
- Institute of Ageing Research, Hangzhou Normal University School of Medicine, Hangzhou 311121, China; (X.H.); (L.W.); (K.Z.); (J.L.)
| | - Jun-Ping Liu
- Institute of Ageing Research, Hangzhou Normal University School of Medicine, Hangzhou 311121, China; (X.H.); (L.W.); (K.Z.); (J.L.)
- Department of Immunology and Pathology, Monash University Faculty of Medicine, Prahran, VIC 3181, Australia
- Hudson Institute of Medical Research, Monash University Department of Molecular and Translational Science, Clayton, VIC 3168, Australia
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37
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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: 2.0] [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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Pandey S, Hajikazemi M, Zacheja T, Schalbetter S, Baxter J, Guryev V, Hofmann A, Heermann DW, Juranek SA, Paeschke K. Telomerase subunit Est2 marks internal sites that are prone to accumulate DNA damage. BMC Biol 2021; 19:247. [PMID: 34801008 PMCID: PMC8605574 DOI: 10.1186/s12915-021-01167-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 10/15/2021] [Indexed: 12/14/2022] Open
Abstract
Background The main function of telomerase is at the telomeres but under adverse conditions telomerase can bind to internal regions causing deleterious effects as observed in cancer cells. Results By mapping the global occupancy of the catalytic subunit of telomerase (Est2) in the budding yeast Saccharomyces cerevisiae, we reveal that it binds to multiple guanine-rich genomic loci, which we termed “non-telomeric binding sites” (NTBS). We characterize Est2 binding to NTBS. Contrary to telomeres, Est2 binds to NTBS in G1 and G2 phase independently of Est1 and Est3. The absence of Est1 and Est3 renders telomerase inactive at NTBS. However, upon global DNA damage, Est1 and Est3 join Est2 at NTBS and telomere addition can be observed indicating that Est2 occupancy marks NTBS regions as particular risks for genome stability. Conclusions Our results provide a novel model of telomerase regulation in the cell cycle using internal regions as “parking spots” of Est2 but marking them as hotspots for telomere addition. Supplementary Information The online version contains supplementary material available at 10.1186/s12915-021-01167-1.
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Affiliation(s)
- Satyaprakash Pandey
- University of Groningen, University Medical Center Groningen, European Research Institute for the Biology of Ageing, 9713 AV, Groningen, Netherlands
| | - Mona Hajikazemi
- Clinic of Internal Medicine III, Oncology, Hematology, Rheumatology and Clinical Immunology, University Hospital Bonn, Bonn, Germany
| | - Theresa Zacheja
- Clinic of Internal Medicine III, Oncology, Hematology, Rheumatology and Clinical Immunology, University Hospital Bonn, Bonn, Germany
| | | | - Jonathan Baxter
- Department of Life Science, University of Sussex, Brighton, UK
| | - Victor Guryev
- University of Groningen, University Medical Center Groningen, European Research Institute for the Biology of Ageing, 9713 AV, Groningen, Netherlands
| | - Andreas Hofmann
- Institute for Theoretical Physics, University of Heidelberg, Philosophenweg 12, 69120, Heidelberg, Germany
| | - Dieter W Heermann
- Institute for Theoretical Physics, University of Heidelberg, Philosophenweg 12, 69120, Heidelberg, Germany
| | - Stefan A Juranek
- Clinic of Internal Medicine III, Oncology, Hematology, Rheumatology and Clinical Immunology, University Hospital Bonn, Bonn, Germany.
| | - Katrin Paeschke
- University of Groningen, University Medical Center Groningen, European Research Institute for the Biology of Ageing, 9713 AV, Groningen, Netherlands. .,Clinic of Internal Medicine III, Oncology, Hematology, Rheumatology and Clinical Immunology, University Hospital Bonn, Bonn, Germany.
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Zaug AJ, Lim CJ, Olson CL, Carilli MT, Goodrich K, Wuttke D, Cech T. CST does not evict elongating telomerase but prevents initiation by ssDNA binding. Nucleic Acids Res 2021; 49:11653-11665. [PMID: 34718732 PMCID: PMC8599947 DOI: 10.1093/nar/gkab942] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 09/29/2021] [Accepted: 10/01/2021] [Indexed: 11/13/2022] Open
Abstract
The CST complex (CTC1-STN1-TEN1) has been shown to inhibit telomerase extension of the G-strand of telomeres and facilitate the switch to C-strand synthesis by DNA polymerase alpha-primase (pol α-primase). Recently the structure of human CST was solved by cryo-EM, allowing the design of mutant proteins defective in telomeric ssDNA binding and prompting the reexamination of CST inhibition of telomerase. The previous proposal that human CST inhibits telomerase by sequestration of the DNA primer was tested with a series of DNA-binding mutants of CST and modeled by a competitive binding simulation. The DNA-binding mutants had substantially reduced ability to inhibit telomerase, as predicted from their reduced affinity for telomeric DNA. These results provide strong support for the previous primer sequestration model. We then tested whether addition of CST to an ongoing processive telomerase reaction would terminate DNA extension. Pulse-chase telomerase reactions with addition of either wild-type CST or DNA-binding mutants showed that CST has no detectable ability to terminate ongoing telomerase extension in vitro. The same lack of inhibition was observed with or without pol α-primase bound to CST. These results suggest how the switch from telomerase extension to C-strand synthesis may occur.
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Affiliation(s)
- Arthur J Zaug
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80309, USA
- BioFrontiers Institute, University of Colorado Boulder, Boulder, CO 80309, USA
- Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Ci Ji Lim
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80309, USA
- BioFrontiers Institute, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Conner L Olson
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Maria T Carilli
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Karen J Goodrich
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80309, USA
- BioFrontiers Institute, University of Colorado Boulder, Boulder, CO 80309, USA
- Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Deborah S Wuttke
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Thomas R Cech
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80309, USA
- BioFrontiers Institute, University of Colorado Boulder, Boulder, CO 80309, USA
- Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO 80309, USA
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Lin CYG, Näger AC, Lunardi T, Vančevska A, Lossaint G, Lingner J. The human telomeric proteome during telomere replication. Nucleic Acids Res 2021; 49:12119-12135. [PMID: 34747482 PMCID: PMC8643687 DOI: 10.1093/nar/gkab1015] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 10/07/2021] [Accepted: 10/13/2021] [Indexed: 11/13/2022] Open
Abstract
Telomere shortening can cause detrimental diseases and contribute to aging. It occurs due to the end replication problem in cells lacking telomerase. Furthermore, recent studies revealed that telomere shortening can be attributed to difficulties of the semi-conservative DNA replication machinery to replicate the bulk of telomeric DNA repeats. To investigate telomere replication in a comprehensive manner, we develop QTIP-iPOND - Quantitative Telomeric chromatin Isolation Protocol followed by isolation of Proteins On Nascent DNA - which enables purification of proteins that associate with telomeres specifically during replication. In addition to the core replisome, we identify a large number of proteins that specifically associate with telomere replication forks. Depletion of several of these proteins induces telomere fragility validating their importance for telomere replication. We also find that at telomere replication forks the single strand telomere binding protein POT1 is depleted, whereas histone H1 is enriched. Our work reveals the dynamic changes of the telomeric proteome during replication, providing a valuable resource of telomere replication proteins. To our knowledge, this is the first study that examines the replisome at a specific region of the genome.
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Affiliation(s)
- Chih-Yi Gabriela Lin
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Anna Christina Näger
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Thomas Lunardi
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Aleksandra Vančevska
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Gérald Lossaint
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Joachim Lingner
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
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41
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Gruber HJ, Semeraro MD, Renner W, Herrmann M. Telomeres and Age-Related Diseases. Biomedicines 2021; 9:1335. [PMID: 34680452 PMCID: PMC8533433 DOI: 10.3390/biomedicines9101335] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 09/20/2021] [Accepted: 09/23/2021] [Indexed: 12/24/2022] Open
Abstract
Telomeres are at the non-coding ends of linear chromosomes. Through a complex 3-dimensional structure, they protect the coding DNA and ensure appropriate separation of chromosomes. Aging is characterized by a progressive shortening of telomeres, which compromises their structure and function. Because of their protective function for genomic DNA, telomeres appear to play an important role in the development and progression of many age-related diseases, such as cardiovascular disease (CVD), malignancies, dementia, and osteoporosis. Despite substantial evidence that links telomere length with these conditions, the nature of these observations remains insufficiently understood. Therefore, future studies should address the question of causality. Furthermore, analytical methods should be further improved with the aim to provide informative and comparable results. This review summarize the actual knowledge of telomere biology and the possible implications of telomere dysfunction for the development and progression of age-related diseases. Furthermore, we provide an overview of analytical techniques for the measurement of telomere length and telomerase activity.
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Affiliation(s)
| | | | - Wilfried Renner
- Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Graz, 8036 Graz, Austria; (H.-J.G.); (M.D.S.); (M.H.)
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42
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TRIM28 is a transcriptional activator of the mutant TERT promoter in human bladder cancer. Proc Natl Acad Sci U S A 2021; 118:2102423118. [PMID: 34518220 DOI: 10.1073/pnas.2102423118] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/30/2021] [Indexed: 12/20/2022] Open
Abstract
Bladder cancer (BC) has a 70% telomerase reverse transcriptase (TERT or hTERT in humans) promoter mutation prevalence, commonly at -124 base pairs, and this is associated with increased hTERT expression and poor patient prognosis. We inserted a green fluorescent protein (GFP) tag in the mutant hTERT promoter allele to create BC cells expressing an hTERT-GFP fusion protein. These cells were used in a fluorescence-activated cell sorting-based pooled CRISPR-Cas9 Kinome knockout genetic screen to identify tripartite motif containing 28 (TRIM28) and TRIM24 as regulators of hTERT expression. TRIM28 activates, while TRIM24 suppresses, hTERT transcription from the mutated promoter allele. TRIM28 is recruited to the mutant promoter where it interacts with TRIM24, which inhibits its activity. Phosphorylation of TRIM28 through the mTOR complex 1 (mTORC1) releases it from TRIM24 and induces hTERT transcription. TRIM28 expression promotes in vitro and in vivo BC cell growth and stratifies BC patient outcome. mTORC1 inhibition with rapamycin analog Ridaforolimus suppresses TRIM28 phosphorylation, hTERT expression, and cell viability. This study may lead to hTERT-directed cancer therapies with reduced effects on normal progenitor cells.
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43
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The structurally conserved TELR region on shelterin protein TPP1 is essential for telomerase processivity but not recruitment. Proc Natl Acad Sci U S A 2021; 118:2024889118. [PMID: 34282008 DOI: 10.1073/pnas.2024889118] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The shelterin protein TPP1 is involved in both recruiting telomerase and stimulating telomerase processivity in human cells. Assessing the in vivo significance of the latter role of TPP1 has been difficult, because TPP1 mutations that perturb telomerase function tend to abolish both telomerase recruitment and processivity. The Saccharomyces cerevisiae telomerase-associated Est3 protein adopts a protein fold similar to the N-terminal region of TPP1. Interestingly, a previous structure-guided mutagenesis study of Est3 revealed a TELR surface region that regulates telomerase function via an unknown mechanism without affecting the interaction between Est3 and telomerase [T. Rao et al., Proc. Natl. Acad. Sci. U.S.A. 111, 214-218 (2014)]. Here, we show that mutations within the structurally conserved TELR region on human TPP1 impaired telomerase processivity while leaving telomerase recruitment unperturbed, hence uncoupling the two roles of TPP1 in regulating telomerase. Telomeres in cell lines containing homozygous TELR mutations progressively shortened to a critical length that caused cellular senescence, despite the presence of abundant telomerase in these cells. Our findings not only demonstrate that telomerase processivity can be regulated by TPP1 in a process separable from its role in recruiting telomerase, but also establish that the in vivo stimulation of telomerase processivity by TPP1 is critical for telomere length homeostasis and long-term viability of human cells.
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44
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Lin X, Qi Y, Latham AP, Zhang B. Multiscale modeling of genome organization with maximum entropy optimization. J Chem Phys 2021; 155:010901. [PMID: 34241389 PMCID: PMC8253599 DOI: 10.1063/5.0044150] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 04/28/2021] [Indexed: 12/15/2022] Open
Abstract
Three-dimensional (3D) organization of the human genome plays an essential role in all DNA-templated processes, including gene transcription, gene regulation, and DNA replication. Computational modeling can be an effective way of building high-resolution genome structures and improving our understanding of these molecular processes. However, it faces significant challenges as the human genome consists of over 6 × 109 base pairs, a system size that exceeds the capacity of traditional modeling approaches. In this perspective, we review the progress that has been made in modeling the human genome. Coarse-grained models parameterized to reproduce experimental data via the maximum entropy optimization algorithm serve as effective means to study genome organization at various length scales. They have provided insight into the principles of whole-genome organization and enabled de novo predictions of chromosome structures from epigenetic modifications. Applications of these models at a near-atomistic resolution further revealed physicochemical interactions that drive the phase separation of disordered proteins and dictate chromatin stability in situ. We conclude with an outlook on the opportunities and challenges in studying chromosome dynamics.
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Affiliation(s)
- Xingcheng Lin
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Yifeng Qi
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Andrew P. Latham
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Bin Zhang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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45
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Fernandes N, Buchan JR. RNAs as Regulators of Cellular Matchmaking. Front Mol Biosci 2021; 8:634146. [PMID: 33898516 PMCID: PMC8062979 DOI: 10.3389/fmolb.2021.634146] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 02/22/2021] [Indexed: 12/30/2022] Open
Abstract
RNA molecules are increasingly being identified as facilitating or impeding the interaction of proteins and nucleic acids, serving as so-called scaffolds or decoys. Long non-coding RNAs have been commonly implicated in such roles, particularly in the regulation of nuclear processes including chromosome topology, regulation of chromatin state and gene transcription, and assembly of nuclear biomolecular condensates such as paraspeckles. Recently, an increased awareness of cytoplasmic RNA scaffolds and decoys has begun to emerge, including the identification of non-coding regions of mRNAs that can also function in a scaffold-like manner to regulate interactions of nascently translated proteins. Collectively, cytoplasmic RNA scaffolds and decoys are now implicated in processes such as mRNA translation, decay, protein localization, protein degradation and assembly of cytoplasmic biomolecular condensates such as P-bodies. Here, we review examples of RNA scaffolds and decoys in both the nucleus and cytoplasm, illustrating common themes, the suitability of RNA to such roles, and future challenges in identifying and better understanding RNA scaffolding and decoy functions.
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Affiliation(s)
| | - J. Ross Buchan
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ, United States
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46
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Bonnell E, Pasquier E, Wellinger RJ. Telomere Replication: Solving Multiple End Replication Problems. Front Cell Dev Biol 2021; 9:668171. [PMID: 33869233 PMCID: PMC8047117 DOI: 10.3389/fcell.2021.668171] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Accepted: 03/10/2021] [Indexed: 12/19/2022] Open
Abstract
Eukaryotic genomes are highly complex and divided into linear chromosomes that require end protection from unwarranted fusions, recombination, and degradation in order to maintain genomic stability. This is accomplished through the conserved specialized nucleoprotein structure of telomeres. Due to the repetitive nature of telomeric DNA, and the unusual terminal structure, namely a protruding single stranded 3' DNA end, completing telomeric DNA replication in a timely and efficient manner is a challenge. For example, the end replication problem causes a progressive shortening of telomeric DNA at each round of DNA replication, thus telomeres eventually lose their protective capacity. This phenomenon is counteracted by the recruitment and the activation at telomeres of the specialized reverse transcriptase telomerase. Despite the importance of telomerase in providing a mechanism for complete replication of telomeric ends, the majority of telomere replication is in fact carried out by the conventional DNA replication machinery. There is significant evidence demonstrating that progression of replication forks is hampered at chromosomal ends due to telomeric sequences prone to form secondary structures, tightly DNA-bound proteins, and the heterochromatic nature of telomeres. The telomeric loop (t-loop) formed by invasion of the 3'-end into telomeric duplex sequences may also impede the passage of replication fork. Replication fork stalling can lead to fork collapse and DNA breaks, a major cause of genomic instability triggered notably by unwanted repair events. Moreover, at chromosomal ends, unreplicated DNA distal to a stalled fork cannot be rescued by a fork coming from the opposite direction. This highlights the importance of the multiple mechanisms involved in overcoming fork progression obstacles at telomeres. Consequently, numerous factors participate in efficient telomeric DNA duplication by preventing replication fork stalling or promoting the restart of a stalled replication fork at telomeres. In this review, we will discuss difficulties associated with the passage of the replication fork through telomeres in both fission and budding yeasts as well as mammals, highlighting conserved mechanisms implicated in maintaining telomere integrity during replication, thus preserving a stable genome.
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Affiliation(s)
| | | | - Raymund J. Wellinger
- Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Cancer Research Pavilion, Université de Sherbrooke, Sherbrooke, QC, Canada
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47
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Yu Z, Jiang F, Hu C, Tang B. Functionalized nanoprobes for in situ detection of telomerase. Chem Commun (Camb) 2021; 57:3736-3748. [PMID: 33876119 DOI: 10.1039/d0cc08412c] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Telomerase, a special ribonucleoprotein reverse transcriptase, can maintain the length and stability of telomeres and plays an important role in cell proliferation and differentiation. Due to the distinguishable expression level in normal cells and cancer cells, telomerase has become an important biomarker for cancer diagnosis and prognosis evaluation. Despite major breakthroughs in the field of telomerase detection, the extracts in the cell lysate are still the first choice as the analyte nevertheless, which will bring serious inaccuracies compared with the real intracellular activity. With the development of nanotechnology and nanomaterials, extraordinary progress has been made in telomerase detection by employing different versatile nanoprobes. In this review, we list the superiority of nanoprobes and systematically summarize the applications of nanoprobes in telomerase detection from the aspects of various nanomaterials and discuss the current challenges and potential trends in the future design of nanoprobes.
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Affiliation(s)
- Zhengze Yu
- College of Chemistry and Chemical Engineering, Qingdao University, Qingdao, 266071, P. R. China.
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48
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Shao S, Zhang H, Zeng Y, Li Y, Sun C, Sun Y. TagBiFC technique allows long-term single-molecule tracking of protein-protein interactions in living cells. Commun Biol 2021; 4:378. [PMID: 33742089 PMCID: PMC7979928 DOI: 10.1038/s42003-021-01896-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 02/12/2021] [Indexed: 01/09/2023] Open
Abstract
Protein-protein interactions (PPIs) are critical for cellular activity regulation. Visualization of PPIs using bimolecular fluorescence complementation (BiFC) techniques helps to understand how PPIs implement their functions. However, current BiFC is based on fluorescent proteins and the brightness and photostability are suboptimal for single molecule tracking experiments, resulting in either low spatiotemporal resolution or incapability of tracking for extended time course. Here, we developed the TagBiFC technique based on split HaloTag, a self-labeling tag that could conjugate an organic dye molecule and thus offered better brightness and photostability than fluorescent proteins for PPI visualization inside living cells. Through screening and optimization, we demonstrated that the reconstituted HaloTag exhibited higher localization precision and longer tracking length than previous methods. Using TagBiFC, we reveal that the dynamic interactions of transcription factor dimers with chromatin DNA are distinct and closely related to their dimeric states, indicating a general regulatory mechanism for these kinds of transcription factors. In addition, we also demonstrated the advantageous applications of TagBiFC in single nucleosome imaging, light-burden imaging of single mRNA, low background imaging of cellular structures. We believe these superior properties of our TagBiFC system will have broad applications in the studies of single molecule imaging inside living cells.
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Affiliation(s)
- Shipeng Shao
- State Key Laboratory of Membrane Biology, Biomedical Pioneering Innovation Center (BIOPIC), School of Life Sciences, Peking University, Beijing, China.,Beijing Institute of Heart Lung and Blood Vessel Disease, Beijing Anzhen Hospital, Capital Medical University, Beijing, China
| | - Hongchen Zhang
- State Key Laboratory of Membrane Biology, Biomedical Pioneering Innovation Center (BIOPIC), School of Life Sciences, Peking University, Beijing, China
| | - Yong Zeng
- Beijing Institute of Heart Lung and Blood Vessel Disease, Beijing Anzhen Hospital, Capital Medical University, Beijing, China
| | - Yongliang Li
- State Key Laboratory of Membrane Biology, Biomedical Pioneering Innovation Center (BIOPIC), School of Life Sciences, Peking University, Beijing, China.,The Second Dental Center, Peking University School and Hospital of Stomatology, Beijing, China
| | - Chaoying Sun
- State Key Laboratory of Membrane Biology, Biomedical Pioneering Innovation Center (BIOPIC), School of Life Sciences, Peking University, Beijing, China
| | - Yujie Sun
- State Key Laboratory of Membrane Biology, Biomedical Pioneering Innovation Center (BIOPIC), School of Life Sciences, Peking University, Beijing, China.
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Pol α-primase dependent nuclear localization of the mammalian CST complex. Commun Biol 2021; 4:349. [PMID: 33731801 PMCID: PMC7969954 DOI: 10.1038/s42003-021-01845-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 02/11/2021] [Indexed: 01/31/2023] Open
Abstract
The human CST complex composed of CTC1, STN1, and TEN1 is critically involved in telomere maintenance and homeostasis. Specifically, CST terminates telomere extension by inhibiting telomerase access to the telomeric overhang and facilitates lagging strand fill in by recruiting DNA Polymerase alpha primase (Pol α-primase) to the telomeric C-strand. Here we reveal that CST has a dynamic intracellular localization that is cell cycle dependent. We report an increase in nuclear CST several hours after the initiation of DNA replication, followed by exit from the nucleus prior to mitosis. We identify amino acids of CTC1 involved in Pol α-primase binding and nuclear localization. We conclude, the CST complex does not contain a nuclear localization signal (NLS) and suggest that its nuclear localization is reliant on Pol α-primase. Hypomorphic mutations affecting CST nuclear import are associated with telomere syndromes and cancer, emphasizing the important role of this process in health.
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Chen L, Roake CM, Galati A, Bavasso F, Micheli E, Saggio I, Schoeftner S, Cacchione S, Gatti M, Artandi SE, Raffa GD. Loss of Human TGS1 Hypermethylase Promotes Increased Telomerase RNA and Telomere Elongation. Cell Rep 2021; 30:1358-1372.e5. [PMID: 32023455 PMCID: PMC7156301 DOI: 10.1016/j.celrep.2020.01.004] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 11/09/2019] [Accepted: 12/31/2019] [Indexed: 02/08/2023] Open
Abstract
Biogenesis of the human telomerase RNA (hTR) involves a complex series of posttranscriptional modifications, including hypermethylation of the 5' mono-methylguanosine cap to a tri-methylguanosine cap (TMG). How the TMG cap affects hTR maturation is unknown. Here, we show that depletion of trimethylguanosine synthase 1 (TGS1), the enzyme responsible for cap hypermethylation, increases levels of hTR and telomerase. Diminished trimethylation increases hTR association with the cap-binding complex (CBC) and with Sm chaperone proteins. Loss of TGS1 causes an increase in accumulation of mature hTR in both the nucleus and the cytoplasm compared with controls. In TGS1 mutant cells, increased hTR assembles with telomerase reverse transcriptase (TERT) protein to yield elevated active telomerase complexes and increased telomerase activity, resulting in telomere elongation in cultured human cells. Our results show that TGS1-mediated hypermethylation of the hTR cap inhibits hTR accumulation, restrains levels of assembled telomerase, and limits telomere elongation.
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Affiliation(s)
- Lu Chen
- Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Caitlin M Roake
- Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Alessandra Galati
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Roma, Italy
| | - Francesca Bavasso
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Roma, Italy
| | - Emanuela Micheli
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Roma, Italy
| | - Isabella Saggio
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Roma, Italy
| | - Stefan Schoeftner
- Cancer Epigenetic Group, Laboratorio Nazionale Consorzio Interuniversitario Biotecnologie, Trieste, Italy
| | - Stefano Cacchione
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Roma, Italy
| | - Maurizio Gatti
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Roma, Italy; Istituto di Biologia e Patologia Molecolari (IBPM) del CNR, Roma, Italy
| | - Steven E Artandi
- Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA.
| | - Grazia D Raffa
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Roma, Italy.
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