51
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DNA replication is highly resilient and persistent under the challenge of mild replication stress. Cell Rep 2022; 39:110701. [PMID: 35443178 PMCID: PMC9226383 DOI: 10.1016/j.celrep.2022.110701] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 12/21/2021] [Accepted: 03/28/2022] [Indexed: 12/25/2022] Open
Abstract
Mitotic DNA synthesis (MiDAS) has been proposed to restart DNA synthesis during mitosis because of replication fork stalling in late interphase caused by mild replication stress (RS). Contrary to this proposal, we find that cells exposed to mild RS in fact maintain continued DNA replication throughout G2 and during G2-M transition in RAD51- and RAD52-dependent manners. Persistent DNA synthesis is necessary to resolve replication intermediates accumulated in G2 and disengage an ATR-imposed block to mitotic entry. Because of its continual nature, DNA synthesis at very late replication sites can overlap with chromosome condensation, generating the phenomenon of mitotic DNA synthesis. Unexpectedly, we find that the commonly used CDK1 inhibitor RO3306 interferes with replication to preclude detection of G2 DNA synthesis, leading to the impression of a mitosis-driven response. Our study reveals the importance of persistent DNA replication and checkpoint control to lessen the risk for severe genome under-replication under mild RS. DNA synthesis persists during G2-M transition to counteract replication stress (RS) RAD51/RAD52-mediated HR pathways facilitate the continuation of G2-M DNA synthesis Continued G2 DNA synthesis relieves RS-induced G2/M checkpoint for mitotic entry RO3306, but not CDK1 inhibition, non-specifically interferes with DNA synthesis
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52
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Mehta S, Zhang J. Liquid-liquid phase separation drives cellular function and dysfunction in cancer. Nat Rev Cancer 2022; 22:239-252. [PMID: 35149762 PMCID: PMC10036213 DOI: 10.1038/s41568-022-00444-7] [Citation(s) in RCA: 119] [Impact Index Per Article: 59.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 01/12/2022] [Indexed: 12/11/2022]
Abstract
Cancer is a disease of uncontrollably reproducing cells. It is governed by biochemical pathways that have escaped the regulatory bounds of normal homeostatic balance. This balance is maintained through precise spatiotemporal regulation of these pathways. The formation of biomolecular condensates via liquid-liquid phase separation (LLPS) has recently emerged as a widespread mechanism underlying the spatiotemporal coordination of biological activities in cells. Biomolecular condensates are widely observed to directly regulate key cellular processes involved in cancer cell pathology, and the dysregulation of LLPS is increasingly implicated as a previously hidden driver of oncogenic activity. In this Perspective, we discuss how LLPS shapes the biochemical landscape of cancer cells.
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Affiliation(s)
- Sohum Mehta
- Department of Pharmacology, University of California, San Diego, La Jolla, CA, USA
| | - Jin Zhang
- Department of Pharmacology, University of California, San Diego, La Jolla, CA, USA.
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA.
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, USA.
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53
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Lu R, Pickett HA. Telomeric replication stress: the beginning and the end for alternative lengthening of telomeres cancers. Open Biol 2022; 12:220011. [PMID: 35259951 PMCID: PMC8905155 DOI: 10.1098/rsob.220011] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Telomeres are nucleoprotein structures that cap the ends of linear chromosomes. Telomeric DNA comprises terminal tracts of G-rich tandem repeats, which are inherently difficult for the replication machinery to navigate. Structural aberrations that promote activation of the alternative lengthening of telomeres (ALT) pathway of telomere maintenance exacerbate replication stress at ALT telomeres, driving fork stalling and fork collapse. This form of telomeric DNA damage perpetuates recombination-mediated repair pathways and break-induced telomere synthesis. The relationship between replication stress and DNA repair is tightly coordinated for the purpose of regulating telomere length in ALT cells, but has been shown to be experimentally manipulatable. This raises the intriguing possibility that induction of replication stress can be used as a means to cause toxic levels of DNA damage at ALT telomeres, thereby selectively disrupting the viability of ALT cancers.
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Affiliation(s)
- Robert Lu
- Telomere Length Regulation Unit, Children's Medical Research Institute, Faculty of Medicine and Health, University of Sydney, Westmead, NSW 2145, Australia
| | - Hilda A. Pickett
- Telomere Length Regulation Unit, Children's Medical Research Institute, Faculty of Medicine and Health, University of Sydney, Westmead, NSW 2145, Australia
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54
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Harapas CR, Idiiatullina E, Al-Azab M, Hrovat-Schaale K, Reygaerts T, Steiner A, Laohamonthonkul P, Davidson S, Yu CH, Booty L, Masters SL. Organellar homeostasis and innate immune sensing. Nat Rev Immunol 2022; 22:535-549. [PMID: 35197578 DOI: 10.1038/s41577-022-00682-8] [Citation(s) in RCA: 45] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/18/2022] [Indexed: 02/06/2023]
Abstract
A cell is delimited by numerous borders that define specific organelles. The walls of some organelles are particularly robust, such as in mitochondria or endoplasmic reticulum, but some are more fluid such as in phase-separated stress granules. Either way, all organelles can be damaged at times, leading their contents to leak out into the surrounding environment. Therefore, an elegant way to construct an innate immune defence system is to recognize host molecules that do not normally reside within a particular compartment. Here, we provide several examples where organellar homeostasis is lost, leading to the activation of a specific innate immune sensor; these include NLRP3 activation owing to a disrupted trans-Golgi network, Pyrin activation due to cytoskeletal damage, and cGAS-STING activation following the leakage of nuclear or mitochondrial DNA. Frequently, organelle damage is observed downstream of pathogenic infection but it can also occur in sterile settings as associated with auto-inflammatory disease. Therefore, understanding organellar homeostasis is central to efforts that will identify new innate immune pathways, and therapeutics that balance organellar homeostasis, or target the breakdown pathways that trigger innate immune sensors, could be useful treatments for infection and chronic inflammatory diseases.
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Affiliation(s)
- Cassandra R Harapas
- Inflammation Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia.,Department of Medical Biology, University of Melbourne, Melbourne, VIC, Australia
| | - Elina Idiiatullina
- Immunology Laboratory, Guangzhou Institute of Paediatrics, Guangzhou Women and Children's Medical Centre, Guangzhou, Guangdong, China
| | - Mahmoud Al-Azab
- Immunology Laboratory, Guangzhou Institute of Paediatrics, Guangzhou Women and Children's Medical Centre, Guangzhou, Guangdong, China
| | - Katja Hrovat-Schaale
- Inflammation Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia.,Department of Medical Biology, University of Melbourne, Melbourne, VIC, Australia
| | - Thomas Reygaerts
- Inflammation Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia.,Department of Medical Biology, University of Melbourne, Melbourne, VIC, Australia
| | - Annemarie Steiner
- Inflammation Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia.,Department of Medical Biology, University of Melbourne, Melbourne, VIC, Australia.,Institute of Structural Biology, Medical Faculty, University of Bonn, Bonn, Germany
| | - Pawat Laohamonthonkul
- Inflammation Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
| | - Sophia Davidson
- Inflammation Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia.,Department of Medical Biology, University of Melbourne, Melbourne, VIC, Australia
| | - Chien-Hsiung Yu
- Inflammation Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia.,Department of Medical Biology, University of Melbourne, Melbourne, VIC, Australia
| | - Lee Booty
- Immunology Network, Immunology Research Unit, GSK, Stevenage, UK
| | - Seth L Masters
- Inflammation Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia. .,Department of Medical Biology, University of Melbourne, Melbourne, VIC, Australia. .,Immunology Laboratory, Guangzhou Institute of Paediatrics, Guangzhou Women and Children's Medical Centre, Guangzhou, Guangdong, China.
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55
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Abstract
The 14-3-3 family proteins are vital scaffold proteins that ubiquitously expressed in various tissues. They interact with numerous protein targets and mediate many cellular signaling pathways. The 14-3-3 binding motifs are often embedded in intrinsically disordered regions which are closely associated with liquid-liquid phase separation (LLPS). In the past ten years, LLPS has been observed for a variety of proteins and biological processes, indicating that LLPS plays a fundamental role in the formation of membraneless organelles and cellular condensates. While extensive investigations have been performed on 14-3-3 proteins, its involvement in LLPS is overlooked. To date, 14-3-3 proteins have not been reported to undergo LLPS alone or regulate LLPS of their binding partners. To reveal the potential involvement of 14-3-3 proteins in LLPS, in this review, we summarized the LLPS propensity of 14-3-3 binding partners and found that about one half of them may undergo LLPS spontaneously. We further analyzed the phase separation behavior of representative 14-3-3 binders and discussed how 14-3-3 proteins may be involved. By modulating the conformation and valence of interactions and recruiting other molecules, we speculate that 14-3-3 proteins can efficiently regulate the functions of their targets in the context of LLPS. Considering the critical roles of 14-3-3 proteins, there is an urgent need for investigating the involvement of 14-3-3 proteins in the phase separation process of their targets and the underling mechanisms.
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56
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Xu M, Chigumira T, Chen Z, Tones J, Zhao R, Dahl KN, Chenoweth DM, Zhang H. CRISPR Cas13-Based Tools to Track and Manipulate Endogenous Telomeric Repeat-Containing RNAs in Live Cells. Front Mol Biosci 2022; 8:785160. [PMID: 35174207 PMCID: PMC8841788 DOI: 10.3389/fmolb.2021.785160] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 12/22/2021] [Indexed: 12/23/2022] Open
Abstract
TERRA, TElomeric Repeat-containing RNA, is a long non-coding RNA transcribed from telomeres. Emerging evidence indicates that TERRA regulates telomere maintenance and chromosome end protection in normal and cancerous cells. However, the mechanism of how TERRA contributes to telomere functions is still unclear, partially owing to the shortage of approaches to track and manipulate endogenous TERRA molecules in live cells. Here, we developed a method to visualize TERRA in live cells via a combination of CRISPR Cas13 RNA labeling and SunTag technology. Single-particle tracking reveals that TERRA foci undergo anomalous diffusion in a manner that depends on the timescale and telomeric localization. Furthermore, we used a chemically-induced protein dimerization system to manipulate TERRA subcellular localization in live cells. Overall, our approaches to monitor and control TERRA locations in live cells provide powerful tools to better understand its roles in telomere maintenance and genomic integrity.
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Affiliation(s)
- Meng Xu
- Department of Biological Sciences, Mellon College of Science, Carnegie Mellon University, Pittsburgh, PA, United States
| | - Tafadzwa Chigumira
- Department of Chemical Engineering, College of Engineering, Carnegie Mellon University, Pittsburgh, PA, United States
| | - Ziheng Chen
- Department of Biological Sciences, Mellon College of Science, Carnegie Mellon University, Pittsburgh, PA, United States
| | - Jason Tones
- Department of Biological Sciences, Mellon College of Science, Carnegie Mellon University, Pittsburgh, PA, United States
| | - Rongwei Zhao
- Department of Biological Sciences, Mellon College of Science, Carnegie Mellon University, Pittsburgh, PA, United States
| | - Kris Noel Dahl
- Department of Chemical Engineering, College of Engineering, Carnegie Mellon University, Pittsburgh, PA, United States
| | - David M. Chenoweth
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, United States
| | - Huaiying Zhang
- Department of Biological Sciences, Mellon College of Science, Carnegie Mellon University, Pittsburgh, PA, United States
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57
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Identification of Key Proteins from the Alternative Lengthening of Telomeres-Associated Promyelocytic Leukemia Nuclear Bodies Pathway. BIOLOGY 2022; 11:biology11020185. [PMID: 35205052 PMCID: PMC8868596 DOI: 10.3390/biology11020185] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/12/2021] [Revised: 01/07/2022] [Accepted: 01/11/2022] [Indexed: 12/26/2022]
Abstract
Simple Summary The alternative lengthening of telomeres is a telomere maintenance mechanism used by some cancer types to elongate their telomeres without the aid of telomerase. This mechanism contributes to the proliferation and immortality of cancer cells. One of the hallmarks of this mechanism is the interaction with promyelocytic leukemia nuclear bodies, which are suspected to be the key places where telomere extension occurs. Despite the discovery of some mechanisms, elements, key genes, and proteins from the pathway, the alternative lengthening of telomeres mechanism is still poorly understood, and it is highly associated with a poor prognosis. In this study, we combined multiomics approaches with genomic, transcriptomic, and proteomic analyses of 71 genes/proteins related to promyelocytic leukemia nuclear bodies in more than 10,000 cancer samples from The Cancer Genome Atlas Consortium. As a result, 13 key proteins were proposed as candidates for future experimental studies that will validate these proteins as therapeutic markers, which will improve the understanding and treatment of these type of cancers. Abstract Alternative lengthening of telomeres-associated promyelocytic leukemia nuclear bodies (APBs) are a hallmark of telomere maintenance. In the last few years, APBs have been described as the main place where telomeric extension occurs in ALT-positive cancer cell lines. A different set of proteins have been associated with APBs function, however, the molecular mechanisms behind their assembly, colocalization, and clustering of telomeres, among others, remain unclear. To improve the understanding of APBs in the ALT pathway, we integrated multiomics analyses to evaluate genomic, transcriptomic and proteomic alterations, and functional interactions of 71 APBs-related genes/proteins in 32 Pan-Cancer Atlas studies from The Cancer Genome Atlas Consortium (TCGA). As a result, we identified 13 key proteins which showed distinctive mutations, interactions, and functional enrichment patterns across all the cancer types and proposed this set of proteins as candidates for future ex vivo and in vivo analyses that will validate these proteins to improve the understanding of the ALT pathway, fill the current research gap about APBs function and their role in ALT, and be considered as potential therapeutic targets for the diagnosis and treatment of ALT-positive cancers in the future.
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58
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Jack A, Kim Y, Strom AR, Lee DSW, Williams B, Schaub JM, Kellogg EH, Finkelstein IJ, Ferro LS, Yildiz A, Brangwynne CP. Compartmentalization of telomeres through DNA-scaffolded phase separation. Dev Cell 2022; 57:277-290.e9. [PMID: 35077681 PMCID: PMC8988007 DOI: 10.1016/j.devcel.2021.12.017] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 08/25/2021] [Accepted: 12/15/2021] [Indexed: 12/20/2022]
Abstract
Telomeres form unique nuclear compartments that prevent degradation and fusion of chromosome ends by recruiting shelterin proteins and regulating access of DNA damage repair factors. To understand how these dynamic components protect chromosome ends, we combine in vivo biophysical interrogation and in vitro reconstitution of human shelterin. We show that shelterin components form multicomponent liquid condensates with selective biomolecular partitioning on telomeric DNA. Tethering and anomalous diffusion prevent multiple telomeres from coalescing into a single condensate in mammalian cells. However, telomeres coalesce when brought into contact via an optogenetic approach. TRF1 and TRF2 subunits of shelterin drive phase separation, and their N-terminal domains specify interactions with telomeric DNA in vitro. Telomeric condensates selectively recruit telomere-associated factors and regulate access of DNA damage repair factors. We propose that shelterin mediates phase separation of telomeric chromatin, which underlies the dynamic yet persistent nature of the end-protection mechanism.
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Affiliation(s)
- Amanda Jack
- Biophysics Graduate Group, University of California, Berkeley, CA 94720, USA
| | - Yoonji Kim
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Amy R Strom
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Daniel S W Lee
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
| | - Byron Williams
- Molecular Biology and Genetics, Cornell University, Ithaca, NY 14850, USA
| | - Jeffrey M Schaub
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA
| | | | - Ilya J Finkelstein
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA; Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, TX 78712, USA
| | - Luke S Ferro
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA.
| | - Ahmet Yildiz
- Biophysics Graduate Group, University of California, Berkeley, CA 94720, USA; Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA; Physics Department, University of California, Berkeley, CA 94720, USA.
| | - Clifford P Brangwynne
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA; Howard Hughes Medical Institute, Princeton University, Princeton NJ 08544, USA.
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59
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Xia J. Liquid-liquid phase separation: A new perspective to understanding aging and pathogenesis. Biosci Trends 2022; 16:359-362. [DOI: 10.5582/bst.2022.01453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Jufeng Xia
- Arai Japan Medical Institute, Tokyo, Japan
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60
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Epum EA, Haber JE. DNA replication: the recombination connection. Trends Cell Biol 2022; 32:45-57. [PMID: 34384659 PMCID: PMC8688190 DOI: 10.1016/j.tcb.2021.07.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 07/18/2021] [Accepted: 07/20/2021] [Indexed: 01/03/2023]
Abstract
Failure to complete DNA replication is one of the major sources of genome instability leading to aneuploidy, chromosome breakage, and chromosome rearrangements that are associated with human cancer. One of the surprising revelations of the past decade is that the completion of replication at so-called common fragile sites (CFS) occurs very late in the cell cycle - at mitosis - through a process termed MiDAS (mitotic DNA synthesis). MiDAS is strongly related to another cancer-promoting phenomenon: the activation of alternative lengthening of telomeres (ALT). Our understanding of the mechanisms of ALT and MiDAS in mammalian cells has drawn heavily from recent advances in the study of break-induced replication (BIR), especially in budding yeast. We provide new insights into the BIR, MiDAS, and ALT pathways and their shared similarities.
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61
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Barroso-González J, García-Expósito L, Galaviz P, Lynskey ML, Allen JAM, Hoang S, Watkins SC, Pickett HA, O'Sullivan RJ. Anti-recombination function of MutSα restricts telomere extension by ALT-associated homology-directed repair. Cell Rep 2021; 37:110088. [PMID: 34879271 PMCID: PMC8724847 DOI: 10.1016/j.celrep.2021.110088] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 09/13/2021] [Accepted: 11/10/2021] [Indexed: 01/02/2023] Open
Abstract
Alternative lengthening of telomeres (ALT) is a telomere-elongation mechanism observed in ~15% of cancer subtypes. Current models indicate that ALT is mediated by homology-directed repair mechanisms. By disrupting MSH6 gene expression, we show that the deficiency of MutSα (MSH2/MSH6) DNA mismatch repair complex causes striking telomere hyperextension. Mechanistically, we show MutSα is specifically recruited to telomeres in ALT cells by associating with the proliferating-cell nuclear antigen (PCNA) subunit of the ALT telomere replisome. We also provide evidence that MutSα counteracts Bloom (BLM) helicase, which adopts a crucial role in stabilizing hyper-extended telomeres and maintaining the survival of MutSα-deficient ALT cancer cells. Lastly, we propose a model in which MutSα deficiency impairs heteroduplex rejection, leading to premature initiation of telomere DNA synthesis that coincides with an accumulation of telomere variant repeats (TVRs). These findings provide evidence that the MutSα DNA mismatch repair complex acts to restrain unwarranted ALT. Barroso-Gonzalez et al. show that the mismatch repair complex MutSα restricts the alternative lengthening of telomeres (ALT) pathway in cancer cells. MutSα has an anti-recombination function and limits recombination between heteroduplex sequences at telomeres, in part by counteracting the Bloom helicase (BLM).
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Affiliation(s)
- Jonathan Barroso-González
- Department of Pharmacology and Chemical Biology, School of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Laura García-Expósito
- Department of Pharmacology and Chemical Biology, School of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Pablo Galaviz
- Bioinformatics Unit, Children's Medical Research Institute, Faculty of Medicine and Health, University of Sydney, Westmead, NSW 2145, Australia
| | - Michelle Lee Lynskey
- Department of Pharmacology and Chemical Biology, School of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Joshua A M Allen
- Telomere Length Regulation Unit, Children's Medical Research Institute, Faculty of Medicine and Health, University of Sydney, Westmead, NSW 2145, Australia
| | - SongMy Hoang
- Department of Pharmacology and Chemical Biology, School of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Simon C Watkins
- Department of Cell Biology, School of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Hilda A Pickett
- Telomere Length Regulation Unit, Children's Medical Research Institute, Faculty of Medicine and Health, University of Sydney, Westmead, NSW 2145, Australia
| | - Roderick J O'Sullivan
- Department of Pharmacology and Chemical Biology, School of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA.
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62
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Ptak C, Saik NO, Premashankar A, Lapetina DL, Aitchison JD, Montpetit B, Wozniak RW. Phosphorylation-dependent mitotic SUMOylation drives nuclear envelope-chromatin interactions. J Cell Biol 2021; 220:212843. [PMID: 34787675 PMCID: PMC8641411 DOI: 10.1083/jcb.202103036] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 07/30/2021] [Accepted: 09/22/2021] [Indexed: 12/15/2022] Open
Abstract
In eukaryotes, chromatin binding to the inner nuclear membrane (INM) and nuclear pore complexes (NPCs) contributes to spatial organization of the genome and epigenetic programs important for gene expression. In mitosis, chromatin–nuclear envelope (NE) interactions are lost and then formed again as sister chromosomes segregate to postmitotic nuclei. Investigating these processes in S. cerevisiae, we identified temporally and spatially controlled phosphorylation-dependent SUMOylation events that positively regulate postmetaphase chromatin association with the NE. Our work establishes a phosphorylation-mediated targeting mechanism of the SUMO ligase Siz2 to the INM during mitosis, where Siz2 binds to and SUMOylates the VAP protein Scs2. The recruitment of Siz2 through Scs2 is further responsible for a wave of SUMOylation along the INM that supports the assembly and anchorage of subtelomeric chromatin at the INM and localization of an active gene (INO1) to NPCs during the later stages of mitosis and into G1-phase.
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Affiliation(s)
- Christopher Ptak
- Department of Cell Biology, University of Alberta, Edmonton, Alberta, Canada
| | - Natasha O Saik
- Department of Cell Biology, University of Alberta, Edmonton, Alberta, Canada
| | | | - Diego L Lapetina
- Department of Cell Biology, University of Alberta, Edmonton, Alberta, Canada
| | | | - Ben Montpetit
- Department of Cell Biology, University of Alberta, Edmonton, Alberta, Canada.,Department of Viticulture and Enology, University of California Davis, Davis, CA
| | - Richard W Wozniak
- Department of Cell Biology, University of Alberta, Edmonton, Alberta, Canada
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63
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Kent T, Clynes D. Alternative Lengthening of Telomeres: Lessons to Be Learned from Telomeric DNA Double-Strand Break Repair. Genes (Basel) 2021; 12:1734. [PMID: 34828344 PMCID: PMC8619803 DOI: 10.3390/genes12111734] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 10/22/2021] [Accepted: 10/28/2021] [Indexed: 12/25/2022] Open
Abstract
The study of the molecular pathways underlying cancer has given us important insights into how breaks in our DNA are repaired and the dire consequences that can occur when these processes are perturbed. Extensive research over the past 20 years has shown that the key molecular event underpinning a subset of cancers involves the deregulated repair of DNA double-strand breaks (DSBs) at telomeres, which in turn leads to telomere lengthening and the potential for replicative immortality. Here we discuss, in-depth, recent major breakthroughs in our understanding of the mechanisms underpinning this pathway known as the alternative lengthening of telomeres (ALT). We explore how this gives us important insights into how DSB repair at telomeres is regulated, with relevance to the cell-cycle-dependent regulation of repair, repair of stalled replication forks and the spatial regulation of DSB repair.
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Affiliation(s)
- Thomas Kent
- Molecular Haematology Unit, Radcliffe Department of Medicine, The MRC Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DS, UK;
| | - David Clynes
- Department of Oncology, The MRC Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DS, UK
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64
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Yau TY, Sander W, Eidson C, Courey AJ. SUMO Interacting Motifs: Structure and Function. Cells 2021; 10:cells10112825. [PMID: 34831049 PMCID: PMC8616421 DOI: 10.3390/cells10112825] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 10/14/2021] [Accepted: 10/14/2021] [Indexed: 11/16/2022] Open
Abstract
Small ubiquitin-related modifier (SUMO) is a member of the ubiquitin-related protein family. SUMO modulates protein function through covalent conjugation to lysine residues in a large number of proteins. Once covalently conjugated to a protein, SUMO often regulates that protein’s function by recruiting other cellular proteins. Recruitment frequently involves a non-covalent interaction between SUMO and a SUMO-interacting motif (SIM) in the interacting protein. SIMs generally consist of a four-residue-long hydrophobic stretch of amino acids with aliphatic non-polar side chains flanked on one side by negatively charged amino acid residues. The SIM assumes an extended β-strand-like conformation and binds to a conserved hydrophobic groove in SUMO. In addition to hydrophobic interactions between the SIM non-polar core and hydrophobic residues in the groove, the negatively charged residues in the SIM make favorable electrostatic contacts with positively charged residues in and around the groove. The SIM/SUMO interaction can be regulated by the phosphorylation of residues adjacent to the SIM hydrophobic core, which provide additional negative charges for favorable electrostatic interaction with SUMO. The SUMO interactome consists of hundreds or perhaps thousands of SIM-containing proteins, but we do not fully understand how each SUMOylated protein selects the set of SIM-containing proteins appropriate to its function. SIM/SUMO interactions have critical functions in a large number of essential cellular processes including the formation of membraneless organelles by liquid–liquid phase separation, epigenetic regulation of transcription through histone modification, DNA repair, and a variety of host–pathogen interactions.
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65
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Spegg V, Altmeyer M. Biomolecular condensates at sites of DNA damage: More than just a phase. DNA Repair (Amst) 2021; 106:103179. [PMID: 34311273 PMCID: PMC7612016 DOI: 10.1016/j.dnarep.2021.103179] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 07/08/2021] [Accepted: 07/09/2021] [Indexed: 12/12/2022]
Abstract
Protein recruitment to DNA break sites is an integral part of the DNA damage response (DDR). Elucidation of the hierarchy and temporal order with which DNA damage sensors as well as repair and signaling factors assemble around chromosome breaks has painted a complex picture of tightly regulated macromolecular interactions that build specialized compartments to facilitate repair and maintenance of genome integrity. While many of the underlying interactions, e.g. between repair factors and damage-induced histone marks, can be explained by lock-and-key or induced fit binding models assuming fixed stoichiometries, structurally less well defined interactions, such as the highly dynamic multivalent interactions implicated in phase separation, also participate in the formation of multi-protein assemblies in response to genotoxic stress. Although much remains to be learned about these types of cooperative and highly dynamic interactions and their functional roles, the rapidly growing interest in material properties of biomolecular condensates and in concepts from polymer chemistry and soft matter physics to understand biological processes at different scales holds great promises. Here, we discuss nuclear condensates in the context of genome integrity maintenance, highlighting the cooperative potential between clustered stoichiometric binding and phase separation. Rather than viewing them as opposing scenarios, their combined effects can balance structural specificity with favorable physicochemical properties relevant for the regulation and function of multilayered nuclear condensates.
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Affiliation(s)
- Vincent Spegg
- Department of Molecular Mechanisms of Disease, University of Zurich, Zurich, Switzerland
| | - Matthias Altmeyer
- Department of Molecular Mechanisms of Disease, University of Zurich, Zurich, Switzerland.
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66
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Patra U, Müller S. A Tale of Usurpation and Subversion: SUMO-Dependent Integrity of Promyelocytic Leukemia Nuclear Bodies at the Crossroad of Infection and Immunity. Front Cell Dev Biol 2021; 9:696234. [PMID: 34513832 PMCID: PMC8430037 DOI: 10.3389/fcell.2021.696234] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Accepted: 07/30/2021] [Indexed: 12/13/2022] Open
Abstract
Promyelocytic leukemia nuclear bodies (PML NBs) are multi-protein assemblies representing distinct sub-nuclear structures. As phase-separated molecular condensates, PML NBs exhibit liquid droplet-like consistency. A key organizer of the assembly and dynamics of PML NBs is the ubiquitin-like SUMO modification system. SUMO is covalently attached to PML and other core components of PML NBs thereby exhibiting a glue-like function by providing multivalent interactions with proteins containing SUMO interacting motifs (SIMs). PML NBs serve as the catalytic center for nuclear SUMOylation and SUMO-SIM interactions are essential for protein assembly within these structures. Importantly, however, formation of SUMO chains on PML and other PML NB-associated proteins triggers ubiquitylation and proteasomal degradation which coincide with disruption of these nuclear condensates. To date, a plethora of nuclear activities such as transcriptional and post-transcriptional regulation of gene expression, apoptosis, senescence, cell cycle control, DNA damage response, and DNA replication have been associated with PML NBs. Not surprisingly, therefore, SUMO-dependent PML NB integrity has been implicated in regulating many physiological processes including tumor suppression, metabolism, drug-resistance, development, cellular stemness, and anti-pathogen immune response. The interplay between PML NBs and viral infection is multifaceted. As a part of the cellular antiviral defense strategy, PML NB components are crucial restriction factors for many viruses and a mutual positive correlation has been found to exist between PML NBs and the interferon response. Viruses, in turn, have developed counterstrategies for disarming PML NB associated immune defense measures. On the other end of the spectrum, certain viruses are known to usurp specific PML NB components for successful replication and disruption of these sub-nuclear foci has recently been linked to the stimulation rather than curtailment of antiviral gene repertoire. Importantly, the ability of invading virions to manipulate the host SUMO modification machinery is essential for this interplay between PML NB integrity and viruses. Moreover, compelling evidence is emerging in favor of bacterial pathogens to negotiate with the SUMO system thereby modulating PML NB-directed intrinsic and innate immunity. In the current context, we will present an updated account of the dynamic intricacies between cellular PML NBs as the nuclear SUMO modification hotspots and immune regulatory mechanisms in response to viral and bacterial pathogens.
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Affiliation(s)
- Upayan Patra
- Institute of Biochemistry II, Faculty of Medicine, Goethe University, Frankfurt, Germany
| | - Stefan Müller
- Institute of Biochemistry II, Faculty of Medicine, Goethe University, Frankfurt, Germany
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67
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Wu X, Malkova A. Break-induced replication mechanisms in yeast and mammals. Curr Opin Genet Dev 2021; 71:163-170. [PMID: 34481360 DOI: 10.1016/j.gde.2021.08.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 07/17/2021] [Accepted: 08/05/2021] [Indexed: 11/26/2022]
Abstract
Break-induced replication (BIR) is a pathway specialized in repair of double-strand DNA breaks with only one end capable of invading homologous template that can arise following replication collapse, telomere erosion or DNA cutting by site-specific endonucleases. For a long time, yeast remained the only model system to study BIR. Studies in yeast demonstrated that BIR represents an unusual mode of DNA synthesis that is driven by a migrating bubble and leads to conservative inheritance of newly synthesized DNA. This unusual type of DNA synthesis leads to high levels of mutations and chromosome rearrangements. Recently, multiple examples of BIR were uncovered in mammalian cells that allowed the comparison of BIR between organisms. It appeared initially that BIR in mammalian cells is predominantly independent of RAD51, and therefore different from BIR that is predominantly Rad51-dependent in yeast. However, a series of systematic studies utilizing site-specific DNA breaks for BIR initiation in mammalian reporters led to the discovery of highly efficient RAD51-dependent BIR, allowing side-by side comparison with BIR in yeast which is the focus of this review.
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Affiliation(s)
- Xiaohua Wu
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, United States.
| | - Anna Malkova
- Department of Biology, University of Iowa, Iowa City, IA 52242, United States.
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68
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Yang SY, Chang EYC, Lim J, Kwan HH, Monchaud D, Yip S, Stirling PC, Wong JMY. G-quadruplexes mark alternative lengthening of telomeres. NAR Cancer 2021; 3:zcab031. [PMID: 34316718 PMCID: PMC8294677 DOI: 10.1093/narcan/zcab031] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 06/29/2021] [Accepted: 07/05/2021] [Indexed: 11/12/2022] Open
Abstract
About 10-15% of all human cancer cells employ a telomerase-independent recombination-based telomere maintenance method, known as alternative lengthening of telomere (ALT), of which the full mechanism remains incompletely understood. While implicated in previous studies as the initiating signals for ALT telomere repair, the prevalence of non-canonical nucleic acid structures in ALT cancers remains unclear. Extending earlier reports, we observe higher levels of DNA/RNA hybrids (R-loops) in ALT-positive (ALT+) compared to telomerase-positive (TERT+) cells. Strikingly, we observe even more pronounced differences for an associated four-stranded nucleic acid structure, G-quadruplex (G4). G4 signals are found at the telomere and are broadly associated with telomere length and accompanied by DNA damage markers. We establish an interdependent relationship between ALT-associated G4s and R-loops and confirm that these two structures can be spatially linked into unique structures, G-loops, at the telomere. Additionally, stabilization of G4s and R-loops cooperatively enhances ALT-activity. However, co-stabilization at higher doses resulted in cytotoxicity in a synergistic manner. Nuclear G4 signals are significantly and reproducibly different between ALT+ and TERT+ low-grade glioma tumours. Together, we present G4 as a novel hallmark of ALT cancers with potential future applications as a convenient biomarker for identifying ALT+ tumours and as therapeutic targets.
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Affiliation(s)
- Sunny Y Yang
- Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, V6T 1Z3, Canada
| | | | - Joanne Lim
- Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, V6T 1Z3, Canada
| | - Harwood H Kwan
- Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, V6T 1Z3, Canada
| | - David Monchaud
- Institut de Chimie Moléculaire, ICMUB CNRS UMR 6302, UBFC Dijon, 21078 Dijon, France
| | - Stephen Yip
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, V6T 2B5 Canada
| | | | - Judy M Y Wong
- Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, V6T 1Z3, Canada
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69
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Novo CL. A Tale of Two States: Pluripotency Regulation of Telomeres. Front Cell Dev Biol 2021; 9:703466. [PMID: 34307383 PMCID: PMC8300013 DOI: 10.3389/fcell.2021.703466] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Accepted: 06/08/2021] [Indexed: 01/01/2023] Open
Abstract
Inside the nucleus, chromatin is functionally organized and maintained as a complex three-dimensional network of structures with different accessibility such as compartments, lamina associated domains, and membraneless bodies. Chromatin is epigenetically and transcriptionally regulated by an intricate and dynamic interplay of molecular processes to ensure genome stability. Phase separation, a process that involves the spontaneous organization of a solution into separate phases, has been proposed as a mechanism for the timely coordination of several cellular processes, including replication, transcription and DNA repair. Telomeres, the repetitive structures at the end of chromosomes, are epigenetically maintained in a repressed heterochromatic state that prevents their recognition as double-strand breaks (DSB), avoiding DNA damage repair and ensuring cell proliferation. In pluripotent embryonic stem cells, telomeres adopt a non-canonical, relaxed epigenetic state, which is characterized by a low density of histone methylation and expression of telomere non-coding transcripts (TERRA). Intriguingly, this telomere non-canonical conformation is usually associated with chromosome instability and aneuploidy in somatic cells, raising the question of how genome stability is maintained in a pluripotent background. In this review, we will explore how emerging technological and conceptual developments in 3D genome architecture can provide novel mechanistic perspectives for the pluripotent epigenetic paradox at telomeres. In particular, as RNA drives the formation of LLPS, we will consider how pluripotency-associated high levels of TERRA could drive and coordinate phase separation of several nuclear processes to ensure genome stability. These conceptual advances will provide a better understanding of telomere regulation and genome stability within the highly dynamic pluripotent background.
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Affiliation(s)
- Clara Lopes Novo
- The Francis Crick Institute, London, United Kingdom
- Imperial College London, London, United Kingdom
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70
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Cai D, Liu Z, Lippincott-Schwartz J. Biomolecular Condensates and Their Links to Cancer Progression. Trends Biochem Sci 2021; 46:535-549. [PMID: 33579564 DOI: 10.1016/j.tibs.2021.01.002] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 01/04/2021] [Accepted: 01/08/2021] [Indexed: 01/14/2023]
Abstract
Liquid-liquid phase separation (LLPS) has emerged in recent years as an important physicochemical process for organizing diverse processes within cells via the formation of membraneless organelles termed biomolecular condensates. Emerging evidence now suggests that the formation and regulation of biomolecular condensates are also intricately linked to cancer formation and progression. We review the most recent literature linking the existence and/or dissolution of biomolecular condensates to different hallmarks of cancer formation and progression. We then discuss the opportunities that this condensate perspective provides for cancer research and the development of novel therapeutic approaches, including the perturbation of condensates by small-molecule inhibitors.
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Affiliation(s)
- Danfeng Cai
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Zhe Liu
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
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71
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Lamm N, Rogers S, Cesare AJ. Chromatin mobility and relocation in DNA repair. Trends Cell Biol 2021; 31:843-855. [PMID: 34183232 DOI: 10.1016/j.tcb.2021.06.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 06/02/2021] [Accepted: 06/03/2021] [Indexed: 01/17/2023]
Abstract
The nucleus is a dynamic environment containing chromatin, membraneless organelles, and specialized molecular structures at the nuclear membrane. Within the spectrum of DNA repair activities are observations of increased mobility of damaged chromatin and the displacement of DNA lesions to specific nuclear environments. Here, we focus on the role that nuclear-specific filamentous actin plays in mobilizing damaged chromatin in response to DNA double-strand breaks and replication stress. We also examine nuclear pore complexes and promyelocytic leukemia-nuclear bodies as specialized platforms for homology-directed repair. The literature suggests an emerging model where specific types of DNA lesions are subjected to nuclear-derived forces that mobilize damaged chromatin and promote interaction with repair hubs to facilitate specialized repair reactions.
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Affiliation(s)
- Noa Lamm
- Children's Medical Research Institute, University of Sydney, Westmead, New South Wales, 2145, Australia
| | - Samuel Rogers
- Children's Medical Research Institute, University of Sydney, Westmead, New South Wales, 2145, Australia
| | - Anthony J Cesare
- Children's Medical Research Institute, University of Sydney, Westmead, New South Wales, 2145, Australia.
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72
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Lezaja A, Panagopoulos A, Wen Y, Carvalho E, Imhof R, Altmeyer M. RPA shields inherited DNA lesions for post-mitotic DNA synthesis. Nat Commun 2021; 12:3827. [PMID: 34158486 PMCID: PMC8219667 DOI: 10.1038/s41467-021-23806-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 05/11/2021] [Indexed: 02/05/2023] Open
Abstract
The paradigm that checkpoints halt cell cycle progression for genome repair has been challenged by the recent discovery of heritable DNA lesions escaping checkpoint control. How such inherited lesions affect genome function and integrity is not well understood. Here, we identify a new class of heritable DNA lesions, which is marked by replication protein A (RPA), a protein primarily known for shielding single-stranded DNA in S/G2. We demonstrate that post-mitotic RPA foci occur at low frequency during unperturbed cell cycle progression, originate from the previous cell cycle, and are exacerbated upon replication stress. RPA-marked inherited ssDNA lesions are found at telomeres, particularly of ALT-positive cancer cells. We reveal that RPA protects these replication remnants in G1 to allow for post-mitotic DNA synthesis (post-MiDAS). Given that ALT-positive cancer cells exhibit high levels of replication stress and telomere fragility, targeting post-MiDAS might be a new therapeutic opportunity.
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Affiliation(s)
- Aleksandra Lezaja
- grid.7400.30000 0004 1937 0650Department of Molecular Mechanisms of Disease, University of Zurich, Zurich, Switzerland
| | - Andreas Panagopoulos
- grid.7400.30000 0004 1937 0650Department of Molecular Mechanisms of Disease, University of Zurich, Zurich, Switzerland
| | - Yanlin Wen
- grid.7400.30000 0004 1937 0650Department of Molecular Mechanisms of Disease, University of Zurich, Zurich, Switzerland
| | - Edison Carvalho
- grid.7400.30000 0004 1937 0650Department of Molecular Mechanisms of Disease, University of Zurich, Zurich, Switzerland
| | - Ralph Imhof
- grid.7400.30000 0004 1937 0650Department of Molecular Mechanisms of Disease, University of Zurich, Zurich, Switzerland
| | - Matthias Altmeyer
- grid.7400.30000 0004 1937 0650Department of Molecular Mechanisms of Disease, University of Zurich, Zurich, Switzerland
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73
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Impacts of chromatin dynamics and compartmentalization on DNA repair. DNA Repair (Amst) 2021; 105:103162. [PMID: 34182258 DOI: 10.1016/j.dnarep.2021.103162] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 06/10/2021] [Accepted: 06/17/2021] [Indexed: 11/22/2022]
Abstract
The proper spatial organization of DNA, RNA, and proteins is critical for a variety of cellular processes. The genome is organized into numerous functional units, such as topologically associating domains (TADs), the formation of which is regulated by both proteins and RNA. In addition, a group of chromatin-bound proteins with the ability to undergo liquid-liquid phase separation (LLPS) can affect the spatial organization and compartmentalization of chromatin, RNA, and proteins by forming condensates, conferring unique properties to specific chromosomal regions. Although the regulation of DNA repair by histone modifications and chromatin accessibility is well established, the impacts of higher-order chromatin and protein organization on the DNA damage response (DDR) have not been appreciated until recently. In this review, we will focus on the movement of chromatin during the DDR, the compartmentalization of DDR proteins via LLPS, and the roles of membraneless nuclear bodies and transcription in DNA repair. With this backdrop, we will discuss the importance of the spatial organization of chromatin and proteins for the maintenance of genome integrity.
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74
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Verma P, Greenberg RA. Communication between chromatin and homologous recombination. Curr Opin Genet Dev 2021; 71:1-9. [PMID: 34098484 DOI: 10.1016/j.gde.2021.05.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 05/13/2021] [Indexed: 12/24/2022]
Abstract
Higher-order chromatin packing serves as a structural barrier to the recognition and repair of genomic lesions. The initiation and outcome of the repair response is dictated by a highly coordinated yet complex interplay between chromatin modifying enzymes and their cognate readers, damage induced chemical modifications, nucleosome density, transcriptional state, and cell cycle-dependent availability of DNA repair machinery. The physical and chemical properties of the DNA lesions themselves further regulate the nature of ensuing chromatin responses. Here we review recent discoveries across these various contexts, where chromatin regulates the homology-guided double-strand break repair mechanism, homologous recombination, and also highlight the key knowledge gaps vital to generate a holistic understanding of this process and its contributions to genome integrity.
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Affiliation(s)
- Priyanka Verma
- Department of Cancer Biology, Penn Center for Genome Integrity, Basser Center for BRCA, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
| | - Roger A Greenberg
- Department of Cancer Biology, Penn Center for Genome Integrity, Basser Center for BRCA, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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75
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MacKenzie D, Watters AK, To JT, Young MW, Muratori J, Wilkoff MH, Abraham RG, Plummer MM, Zhang D. ALT Positivity in Human Cancers: Prevalence and Clinical Insights. Cancers (Basel) 2021; 13:2384. [PMID: 34069193 PMCID: PMC8156225 DOI: 10.3390/cancers13102384] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 05/07/2021] [Accepted: 05/11/2021] [Indexed: 02/08/2023] Open
Abstract
Many exciting advances in cancer-related telomere biology have been made in the past decade. Of these recent advances, great progress has also been made with respect to the Alternative Lengthening of Telomeres (ALT) pathway. Along with a better understanding of the molecular mechanism of this unique telomere maintenance pathway, many studies have also evaluated ALT activity in various cancer subtypes. We first briefly review and assess a variety of commonly used ALT biomarkers. Then, we provide both an update on ALT-positive (ALT+) tumor prevalence as well as a systematic clinical assessment of the presently studied ALT+ malignancies. Additionally, we discuss the pathogenetic alterations in ALT+ cancers, for example, the mutation status of ATRX and DAXX, and their correlations with the activation of the ALT pathway. Finally, we highlight important ALT+ clinical associations within each cancer subtype and subdivisions within, as well as their prognoses. We hope this alternative perspective will allow scientists, clinicians, and drug developers to have greater insight into the ALT cancers so that together, we may develop more efficacious treatments and improved management strategies to meet the urgent needs of cancer patients.
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Affiliation(s)
| | | | | | | | | | | | | | - Maria M. Plummer
- Department of Biomedical Sciences, College of Osteopathic Medicine, New York Institute of Technology, Old Westbury, NY 11568, USA; (D.M.J.); (A.K.W.); (J.T.T.); (M.W.Y.); (J.M.); (M.H.W.); (R.G.A.)
| | - Dong Zhang
- Department of Biomedical Sciences, College of Osteopathic Medicine, New York Institute of Technology, Old Westbury, NY 11568, USA; (D.M.J.); (A.K.W.); (J.T.T.); (M.W.Y.); (J.M.); (M.H.W.); (R.G.A.)
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76
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Mutations inhibiting KDM4B drive ALT activation in ATRX-mutated glioblastomas. Nat Commun 2021; 12:2584. [PMID: 33972520 PMCID: PMC8110556 DOI: 10.1038/s41467-021-22543-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 03/16/2021] [Indexed: 12/24/2022] Open
Abstract
Alternative Lengthening of Telomeres (ALT) is a telomere maintenance pathway utilised in 15% of cancers. ALT cancers are strongly associated with inactivating mutations in ATRX; yet loss of ATRX alone is insufficient to trigger ALT, suggesting that additional cooperating factors are involved. We identify H3.3G34R and IDH1/2 mutations as two such factors in ATRX-mutated glioblastomas. Both mutations are capable of inactivating histone demethylases, and we identify KDM4B as the key demethylase inactivated in ALT. Mouse embryonic stem cells inactivated for ATRX, TP53, TERT and KDM4B (KDM4B knockout or H3.3G34R) show characteristic features of ALT. Conversely, KDM4B over-expression in ALT cancer cells abrogates ALT-associated features. In this work, we demonstrate that inactivation of KDM4B, through H3.3G34R or IDH1/2 mutations, acts in tandem with ATRX mutations to promote ALT in glioblastomas. Alternative Lengthening of Telomeres (ALT) is a telomere maintenance pathway utilised in 15% of cancers that have been associated with mutations in ATRX. Here the authors reveal a functional role of histone demethylases KDM4B in regulating ALT activation.
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77
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Keiten-Schmitz J, Röder L, Hornstein E, Müller-McNicoll M, Müller S. SUMO: Glue or Solvent for Phase-Separated Ribonucleoprotein Complexes and Molecular Condensates? Front Mol Biosci 2021; 8:673038. [PMID: 34026847 PMCID: PMC8138125 DOI: 10.3389/fmolb.2021.673038] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 04/08/2021] [Indexed: 01/01/2023] Open
Abstract
Spatial organization of cellular processes in membranous or membrane-less organelles (MLOs, alias molecular condensates) is a key concept for compartmentalizing biochemical pathways. Prime examples of MLOs are the nucleolus, PML nuclear bodies, nuclear splicing speckles or cytosolic stress granules. They all represent distinct sub-cellular structures typically enriched in intrinsically disordered proteins and/or RNA and are formed in a process driven by liquid-liquid phase separation. Several MLOs are critically involved in proteostasis and their formation, disassembly and composition are highly sensitive to proteotoxic insults. Changes in the dynamics of MLOs are a major driver of cell dysfunction and disease. There is growing evidence that post-translational modifications are critically involved in controlling the dynamics and composition of MLOs and recent evidence supports an important role of the ubiquitin-like SUMO system in regulating both the assembly and disassembly of these structures. Here we will review our current understanding of SUMO function in MLO dynamics under both normal and pathological conditions.
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Affiliation(s)
- Jan Keiten-Schmitz
- Faculty of Medicine, Institute of Biochemistry II, Goethe University, Frankfurt, Germany
| | - Linda Röder
- Faculty of Medicine, Institute of Biochemistry II, Goethe University, Frankfurt, Germany
| | - Eran Hornstein
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
- Department of Molecular Neuroscience, Weizmann Institute of Science, Rehovot, Israel
| | - Michaela Müller-McNicoll
- Faculty of Biosciences, Institute for Molecular Biosciences, Goethe University, Frankfurt am Main, Germany
| | - Stefan Müller
- Faculty of Medicine, Institute of Biochemistry II, Goethe University, Frankfurt, Germany
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78
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Zhao R, Chenoweth DM, Zhang H. Chemical Dimerization-Induced Protein Condensates on Telomeres. J Vis Exp 2021. [PMID: 33900288 DOI: 10.3791/62173] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Chromatin-associated condensates are implicated in many nuclear processes, but the underlying mechanisms remain elusive. This protocol describes a chemically-induced protein dimerization system to create condensates on telomeres. The chemical dimerizer consists of two linked ligands that can each bind to a protein: Halo ligand to Halo-enzyme and trimethoprim (TMP) to E. coli dihydrofolate reductase (eDHFR), respectively. Fusion of Halo enzyme to a telomere protein anchors dimerizers to telomeres through covalent Halo ligand-enzyme binding. Binding of TMP to eDHFR recruits eDHFR-fused phase separating proteins to telomeres and induces condensate formation. Because TMP-eDHFR interaction is non-covalent, condensation can be reversed by using excess free TMP to compete with the dimerizer for eDHFR binding. An example of inducing promyelocytic leukemia (PML) nuclear body formation on telomeres and determining condensate growth, dissolution, localization and composition is shown. This method can be easily adapted to induce condensates at other genomic locations by fusing Halo to a protein that directly binds to the local chromatin or to dCas9 that is targeted to the genomic locus with a guide RNA. By offering the temporal resolution required for single cell live imaging while maintaining phase separation in a population of cells for biochemical assays, this method is suitable for probing both the formation and function of chromatin-associated condensates.
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Affiliation(s)
- Rongwei Zhao
- Department of Biological Sciences, Mellon College of Science, Carnegie Mellon University
| | - David M Chenoweth
- Department of Chemistry, School of Arts and Sciences, University of Pennsylvania
| | - Huaiying Zhang
- Department of Biological Sciences, Mellon College of Science, Carnegie Mellon University;
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79
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Nersisyan L, Simonyan A, Binder H, Arakelyan A. Telomere Maintenance Pathway Activity Analysis Enables Tissue- and Gene-Level Inferences. Front Genet 2021; 12:662464. [PMID: 33897770 PMCID: PMC8058386 DOI: 10.3389/fgene.2021.662464] [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: 02/01/2021] [Accepted: 03/16/2021] [Indexed: 12/31/2022] Open
Abstract
Telomere maintenance is one of the mechanisms ensuring indefinite divisions of cancer and stem cells. Good understanding of telomere maintenance mechanisms (TMM) is important for studying cancers and designing therapies. However, molecular factors triggering selective activation of either the telomerase dependent (TEL) or the alternative lengthening of telomeres (ALT) pathway are poorly understood. In addition, more accurate and easy-to-use methodologies are required for TMM phenotyping. In this study, we have performed literature based reconstruction of signaling pathways for the ALT and TEL TMMs. Gene expression data were used for computational assessment of TMM pathway activities and compared with experimental assays for TEL and ALT. Explicit consideration of pathway topology makes bioinformatics analysis more informative compared to computational methods based on simple summary measures of gene expression. Application to healthy human tissues showed high ALT and TEL pathway activities in testis, and identified genes and pathways that may trigger TMM activation. Our approach offers a novel option for systematic investigation of TMM activation patterns across cancers and healthy tissues for dissecting pathway-based molecular markers with diagnostic impact.
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Affiliation(s)
- Lilit Nersisyan
- Bioinformatics Group, Institute of Molecular Biology, National Academy of Sciences, Yerevan, Armenia.,Pathverse, Yerevan, Armenia
| | - Arman Simonyan
- Bioinformatics Group, Institute of Molecular Biology, National Academy of Sciences, Yerevan, Armenia
| | - Hans Binder
- Interdisciplinary Center for Bioinformatics, University of Leipzig, Leipzig, Germany
| | - Arsen Arakelyan
- Bioinformatics Group, Institute of Molecular Biology, National Academy of Sciences, Yerevan, Armenia.,Pathverse, Yerevan, Armenia
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80
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King JT, Shakya A. Phase separation of DNA: From past to present. Biophys J 2021; 120:1139-1149. [PMID: 33582138 PMCID: PMC8059212 DOI: 10.1016/j.bpj.2021.01.033] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 01/11/2021] [Accepted: 01/22/2021] [Indexed: 02/08/2023] Open
Abstract
Phase separation of biological molecules, such as nucleic acids and proteins, has garnered widespread attention across many fields in recent years. For instance, liquid-liquid phase separation has been implicated not only in membraneless intracellular organization but also in many biochemical processes, including transcription, translation, and cellular signaling. Here, we present a historical background of biological phase separation and survey current work on nuclear organization and its connection to DNA phase separation from the perspective of DNA sequence, structure, and genomic context.
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Affiliation(s)
- John T King
- Center for Soft and Living Matter, Institute for Basic Science, Ulsan, Republic of Korea.
| | - Anisha Shakya
- Center for Soft and Living Matter, Institute for Basic Science, Ulsan, Republic of Korea.
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81
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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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82
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Luo J, Qu L, Gao F, Lin J, Liu J, Lin A. LncRNAs: Architectural Scaffolds or More Potential Roles in Phase Separation. Front Genet 2021; 12:626234. [PMID: 33868368 PMCID: PMC8044363 DOI: 10.3389/fgene.2021.626234] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 02/25/2021] [Indexed: 12/12/2022] Open
Abstract
Biomolecules specifically aggregate in the cytoplasm and nucleus, driving liquid-liquid phase separation (LLPS) formation and diverse biological processes. Extensive studies have focused on revealing multiple functional membraneless organelles in both the nucleus and cytoplasm. Condensation compositions of LLPS, such as proteins and RNAs affecting the formation of phase separation, have been gradually unveiled. LncRNAs possessing abundant second structures usually promote phase separation formation by providing architectural scaffolds for diverse RNAs and proteins interaction in both the nucleus and cytoplasm. Beyond scaffolds, lncRNAs may possess more diverse functions, such as functioning as enhancer RNAs or buffers. In this review, we summarized current studies on the function of phase separation and its related lncRNAs, mainly in the nucleus. This review will facilitate our understanding of the formation and function of phase separation and the role of lncRNAs in these processes and related biological activities. A deeper understanding of the formation and maintaining of phase separation will be beneficial for disease diagnosis and treatment.
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Affiliation(s)
- Jie Luo
- Department of Obstetrics and Gynecology, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Lei Qu
- College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Feiran Gao
- Department of Respiratory and Critical Care Medicine, The Second Affiliated Hospital, Zhejiang University School of Medicine, Zhejiang University, Hangzhou, China.,Zhejiang University-University of Edinburgh Institute (ZJU-UoE Institute), Zhejiang University School of Medicine, Zhejiang University, Haining, China
| | - Jun Lin
- Department of Obstetrics and Gynecology, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Jian Liu
- Department of Respiratory and Critical Care Medicine, The Second Affiliated Hospital, Zhejiang University School of Medicine, Zhejiang University, Hangzhou, China.,Zhejiang University-University of Edinburgh Institute (ZJU-UoE Institute), Zhejiang University School of Medicine, Zhejiang University, Haining, China
| | - Aifu Lin
- College of Life Sciences, Zhejiang University, Hangzhou, China.,Breast Center of The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
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83
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Kaur E, Agrawal R, Sengupta S. Functions of BLM Helicase in Cells: Is It Acting Like a Double-Edged Sword? Front Genet 2021; 12:634789. [PMID: 33777104 PMCID: PMC7994599 DOI: 10.3389/fgene.2021.634789] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Accepted: 02/11/2021] [Indexed: 12/14/2022] Open
Abstract
DNA damage repair response is an important biological process involved in maintaining the fidelity of the genome in eukaryotes and prokaryotes. Several proteins that play a key role in this process have been identified. Alterations in these key proteins have been linked to different diseases including cancer. BLM is a 3′−5′ ATP-dependent RecQ DNA helicase that is one of the most essential genome stabilizers involved in the regulation of DNA replication, recombination, and both homologous and non-homologous pathways of double-strand break repair. BLM structure and functions are known to be conserved across many species like yeast, Drosophila, mouse, and human. Genetic mutations in the BLM gene cause a rare, autosomal recessive disorder, Bloom syndrome (BS). BS is a monogenic disease characterized by genomic instability, premature aging, predisposition to cancer, immunodeficiency, and pulmonary diseases. Hence, these characteristics point toward BLM being a tumor suppressor. However, in addition to mutations, BLM gene undergoes various types of alterations including increase in the copy number, transcript, and protein levels in multiple types of cancers. These results, along with the fact that the lack of wild-type BLM in these cancers has been associated with increased sensitivity to chemotherapeutic drugs, indicate that BLM also has a pro-oncogenic function. While a plethora of studies have reported the effect of BLM gene mutations in various model organisms, there is a dearth in the studies undertaken to investigate the effect of its oncogenic alterations. We propose to rationalize and integrate the dual functions of BLM both as a tumor suppressor and maybe as a proto-oncogene, and enlist the plausible mechanisms of its deregulation in cancers.
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Affiliation(s)
- Ekjot Kaur
- Signal Transduction Laboratory-2, National Institute of Immunology, New Delhi, India
| | - Ritu Agrawal
- Signal Transduction Laboratory-2, National Institute of Immunology, New Delhi, India
| | - Sagar Sengupta
- Signal Transduction Laboratory-2, National Institute of Immunology, New Delhi, India
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84
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Zhang JM, Genois MM, Ouyang J, Lan L, Zou L. Alternative lengthening of telomeres is a self-perpetuating process in ALT-associated PML bodies. Mol Cell 2021; 81:1027-1042.e4. [PMID: 33453166 PMCID: PMC8245000 DOI: 10.1016/j.molcel.2020.12.030] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 11/03/2020] [Accepted: 12/15/2020] [Indexed: 01/16/2023]
Abstract
Alternative lengthening of telomeres (ALT) is mediated by break-induced replication (BIR), but how BIR is regulated at telomeres is poorly understood. Here, we show that telomeric BIR is a self-perpetuating process. By tethering PML-IV to telomeres, we induced telomere clustering in ALT-associated PML bodies (APBs) and a POLD3-dependent ATR response at telomeres, showing that BIR generates replication stress. Ablation of BLM helicase activity in APBs abolishes telomere synthesis but causes multiple chromosome bridges between telomeres, revealing a function of BLM in processing inter-telomere BIR intermediates. Interestingly, the accumulation of BLM in APBs requires its own helicase activity and POLD3, suggesting that BIR triggers a feedforward loop to further recruit BLM. Enhancing BIR induces PIAS4-mediated TRF2 SUMOylation, and PIAS4 loss deprives APBs of repair proteins and compromises ALT telomere synthesis. Thus, a BLM-driven and PIAS4-mediated feedforward loop operates in APBs to perpetuate BIR, providing a critical mechanism to extend ALT telomeres.
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Affiliation(s)
- Jia-Min Zhang
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, MA 02129, USA
| | - Marie-Michelle Genois
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, MA 02129, USA
| | - Jian Ouyang
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, MA 02129, USA
| | - Li Lan
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, MA 02129, USA; Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Lee Zou
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, MA 02129, USA; Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA.
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85
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Rawat P, Boehning M, Hummel B, Aprile-Garcia F, Pandit AS, Eisenhardt N, Khavaran A, Niskanen E, Vos SM, Palvimo JJ, Pichler A, Cramer P, Sawarkar R. Stress-induced nuclear condensation of NELF drives transcriptional downregulation. Mol Cell 2021; 81:1013-1026.e11. [PMID: 33548202 PMCID: PMC7939545 DOI: 10.1016/j.molcel.2021.01.016] [Citation(s) in RCA: 75] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 10/20/2020] [Accepted: 01/11/2021] [Indexed: 12/21/2022]
Abstract
In response to stress, human cells coordinately downregulate transcription and translation of housekeeping genes. To downregulate transcription, the negative elongation factor (NELF) is recruited to gene promoters impairing RNA polymerase II elongation. Here we report that NELF rapidly forms nuclear condensates upon stress in human cells. Condensate formation requires NELF dephosphorylation and SUMOylation induced by stress. The intrinsically disordered region (IDR) in NELFA is necessary for nuclear NELF condensation and can be functionally replaced by the IDR of FUS or EWSR1 protein. We find that biomolecular condensation facilitates enhanced recruitment of NELF to promoters upon stress to drive transcriptional downregulation. Importantly, NELF condensation is required for cellular viability under stressful conditions. We propose that stress-induced NELF condensates reported here are nuclear counterparts of cytosolic stress granules. These two stress-inducible condensates may drive the coordinated downregulation of transcription and translation, likely forming a critical node of the stress survival strategy.
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Affiliation(s)
- Prashant Rawat
- Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany; Faculty of Biology, University of Freiburg, Freiburg, Germany; International Max Planck Research School for Molecular and Cellular Biology (IMPRS-MCB), Freiburg, Germany.
| | - Marc Boehning
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Barbara Hummel
- Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany
| | | | - Anwit S Pandit
- Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany; CIBSS, Centre for Integrative Biological Signaling Studies, Freiburg, Germany; Spemann Graduate School of Biology and Medicine, Albert Ludwigs University of Freiburg, Freiburg, Germany
| | - Nathalie Eisenhardt
- Department of Epigenetics, Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany
| | - Ashkan Khavaran
- Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany; Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Einari Niskanen
- Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland
| | - Seychelle M Vos
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Jorma J Palvimo
- Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland
| | - Andrea Pichler
- Department of Epigenetics, Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany
| | - Patrick Cramer
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.
| | - Ritwick Sawarkar
- Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany; CIBSS, Centre for Integrative Biological Signaling Studies, Freiburg, Germany; MRC, University of Cambridge, Cambridge, UK.
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86
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Boija A, Klein IA, Young RA. Biomolecular Condensates and Cancer. Cancer Cell 2021; 39:174-192. [PMID: 33417833 PMCID: PMC8721577 DOI: 10.1016/j.ccell.2020.12.003] [Citation(s) in RCA: 140] [Impact Index Per Article: 46.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 12/02/2020] [Accepted: 12/04/2020] [Indexed: 12/14/2022]
Abstract
Malignant transformation is characterized by dysregulation of diverse cellular processes that have been the subject of detailed genetic, biochemical, and structural studies, but only recently has evidence emerged that many of these processes occur in the context of biomolecular condensates. Condensates are membrane-less bodies, often formed by liquid-liquid phase separation, that compartmentalize protein and RNA molecules with related functions. New insights from condensate studies portend a profound transformation in our understanding of cellular dysregulation in cancer. Here we summarize key features of biomolecular condensates, note where they have been implicated-or will likely be implicated-in oncogenesis, describe evidence that the pharmacodynamics of cancer therapeutics can be greatly influenced by condensates, and discuss some of the questions that must be addressed to further advance our understanding and treatment of cancer.
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Affiliation(s)
- Ann Boija
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA.
| | - Isaac A Klein
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA.
| | - Richard A Young
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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87
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Boulanger M, Chakraborty M, Tempé D, Piechaczyk M, Bossis G. SUMO and Transcriptional Regulation: The Lessons of Large-Scale Proteomic, Modifomic and Genomic Studies. Molecules 2021; 26:molecules26040828. [PMID: 33562565 PMCID: PMC7915335 DOI: 10.3390/molecules26040828] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 01/29/2021] [Accepted: 02/01/2021] [Indexed: 12/12/2022] Open
Abstract
One major role of the eukaryotic peptidic post-translational modifier SUMO in the cell is transcriptional control. This occurs via modification of virtually all classes of transcriptional actors, which include transcription factors, transcriptional coregulators, diverse chromatin components, as well as Pol I-, Pol II- and Pol III transcriptional machineries and their regulators. For many years, the role of SUMOylation has essentially been studied on individual proteins, or small groups of proteins, principally dealing with Pol II-mediated transcription. This provided only a fragmentary view of how SUMOylation controls transcription. The recent advent of large-scale proteomic, modifomic and genomic studies has however considerably refined our perception of the part played by SUMO in gene expression control. We review here these developments and the new concepts they are at the origin of, together with the limitations of our knowledge. How they illuminate the SUMO-dependent transcriptional mechanisms that have been characterized thus far and how they impact our view of SUMO-dependent chromatin organization are also considered.
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Affiliation(s)
- Mathias Boulanger
- Institut de Génétique Moléculaire de Montpellier (IGMM), University of Montpellier, CNRS, Montpellier, France; (M.B.); (M.C.); (D.T.)
- Equipe Labellisée Ligue Contre le Cancer, Paris, France
| | - Mehuli Chakraborty
- Institut de Génétique Moléculaire de Montpellier (IGMM), University of Montpellier, CNRS, Montpellier, France; (M.B.); (M.C.); (D.T.)
- Equipe Labellisée Ligue Contre le Cancer, Paris, France
| | - Denis Tempé
- Institut de Génétique Moléculaire de Montpellier (IGMM), University of Montpellier, CNRS, Montpellier, France; (M.B.); (M.C.); (D.T.)
- Equipe Labellisée Ligue Contre le Cancer, Paris, France
| | - Marc Piechaczyk
- Institut de Génétique Moléculaire de Montpellier (IGMM), University of Montpellier, CNRS, Montpellier, France; (M.B.); (M.C.); (D.T.)
- Equipe Labellisée Ligue Contre le Cancer, Paris, France
- Correspondence: (M.P.); (G.B.)
| | - Guillaume Bossis
- Institut de Génétique Moléculaire de Montpellier (IGMM), University of Montpellier, CNRS, Montpellier, France; (M.B.); (M.C.); (D.T.)
- Equipe Labellisée Ligue Contre le Cancer, Paris, France
- Correspondence: (M.P.); (G.B.)
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88
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Alberti S, Hyman AA. Biomolecular condensates at the nexus of cellular stress, protein aggregation disease and ageing. Nat Rev Mol Cell Biol 2021; 22:196-213. [PMID: 33510441 DOI: 10.1038/s41580-020-00326-6] [Citation(s) in RCA: 458] [Impact Index Per Article: 152.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/16/2020] [Indexed: 12/14/2022]
Abstract
Biomolecular condensates are membraneless intracellular assemblies that often form via liquid-liquid phase separation and have the ability to concentrate biopolymers. Research over the past 10 years has revealed that condensates play fundamental roles in cellular organization and physiology, and our understanding of the molecular principles, components and forces underlying their formation has substantially increased. Condensate assembly is tightly regulated in the intracellular environment, and failure to control condensate properties, formation and dissolution can lead to protein misfolding and aggregation, which are often the cause of ageing-associated diseases. In this Review, we describe the mechanisms and regulation of condensate assembly and dissolution, highlight recent advances in understanding the role of biomolecular condensates in ageing and disease, and discuss how cellular stress, ageing-related loss of homeostasis and a decline in protein quality control may contribute to the formation of aberrant, disease-causing condensates. Our improved understanding of condensate pathology provides a promising path for the treatment of protein aggregation diseases.
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Affiliation(s)
- Simon Alberti
- Technische Universität Dresden, Biotechnology Center (BIOTEC) and Center for Molecular and Cellular Engineering (CMCB), Dresden, Germany.
| | - Anthony A Hyman
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany.
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89
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Mathavarajah S, VanIderstine C, Dellaire G, Huber RJ. Cancer and the breakdown of multicellularity: What Dictyostelium discoideum, a social amoeba, can teach us. Bioessays 2021; 43:e2000156. [PMID: 33448043 DOI: 10.1002/bies.202000156] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 12/11/2020] [Accepted: 12/17/2020] [Indexed: 01/01/2023]
Abstract
Ancient pathways promoting unicellularity and multicellularity are associated with cancer, the former being pro-oncogenic and the latter acting to suppress oncogenesis. However, there are only a limited number of non-vertebrate models for studying these pathways. Here, we review Dictyostelium discoideum and describe how it can be used to understand these gene networks. D. discoideum has a unicellular and multicellular life cycle, making it possible to study orthologs of cancer-associated genes in both phases. During development, differentiated amoebae form a fruiting body composed of a mass of spores that are supported atop a stalk. A portion of the cells sacrifice themselves to become non-reproductive stalk cells. Cheating disrupts the principles of multicellularity, as cheater cells alter their cell fate to preferentially become spores. Importantly, D. discoideum has gene networks and several strategies for maintaining multicellularity. Therefore, D. discoideum can help us better understand how conserved genes and pathways involved in multicellularity also influence cancer development, potentially identifying new therapeutic avenues.
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Affiliation(s)
- Sabateeshan Mathavarajah
- Department of Pathology, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Carter VanIderstine
- Department of Pathology, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Graham Dellaire
- Department of Pathology, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada.,Department of Biochemistry and Molecular Biology, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Robert J Huber
- Department of Biology, Trent University, Peterborough, Ontario, Canada
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90
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Corpet A, Kleijwegt C, Roubille S, Juillard F, Jacquet K, Texier P, Lomonte P. PML nuclear bodies and chromatin dynamics: catch me if you can! Nucleic Acids Res 2020; 48:11890-11912. [PMID: 33068409 PMCID: PMC7708061 DOI: 10.1093/nar/gkaa828] [Citation(s) in RCA: 94] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 09/15/2020] [Accepted: 09/18/2020] [Indexed: 12/17/2022] Open
Abstract
Eukaryotic cells compartmentalize their internal milieu in order to achieve specific reactions in time and space. This organization in distinct compartments is essential to allow subcellular processing of regulatory signals and generate specific cellular responses. In the nucleus, genetic information is packaged in the form of chromatin, an organized and repeated nucleoprotein structure that is a source of epigenetic information. In addition, cells organize the distribution of macromolecules via various membrane-less nuclear organelles, which have gathered considerable attention in the last few years. The macromolecular multiprotein complexes known as Promyelocytic Leukemia Nuclear Bodies (PML NBs) are an archetype for nuclear membrane-less organelles. Chromatin interactions with nuclear bodies are important to regulate genome function. In this review, we will focus on the dynamic interplay between PML NBs and chromatin. We report how the structure and formation of PML NBs, which may involve phase separation mechanisms, might impact their functions in the regulation of chromatin dynamics. In particular, we will discuss how PML NBs participate in the chromatinization of viral genomes, as well as in the control of specific cellular chromatin assembly pathways which govern physiological mechanisms such as senescence or telomere maintenance.
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Affiliation(s)
- Armelle Corpet
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR 5310, INSERM U 1217, LabEx DEVweCAN, Institut NeuroMyoGène (INMG), team Chromatin Dynamics, Nuclear Domains, Virus F-69008, Lyon, France
| | - Constance Kleijwegt
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR 5310, INSERM U 1217, LabEx DEVweCAN, Institut NeuroMyoGène (INMG), team Chromatin Dynamics, Nuclear Domains, Virus F-69008, Lyon, France
| | - Simon Roubille
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR 5310, INSERM U 1217, LabEx DEVweCAN, Institut NeuroMyoGène (INMG), team Chromatin Dynamics, Nuclear Domains, Virus F-69008, Lyon, France
| | - Franceline Juillard
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR 5310, INSERM U 1217, LabEx DEVweCAN, Institut NeuroMyoGène (INMG), team Chromatin Dynamics, Nuclear Domains, Virus F-69008, Lyon, France
| | - Karine Jacquet
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR 5310, INSERM U 1217, LabEx DEVweCAN, Institut NeuroMyoGène (INMG), team Chromatin Dynamics, Nuclear Domains, Virus F-69008, Lyon, France
| | - Pascale Texier
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR 5310, INSERM U 1217, LabEx DEVweCAN, Institut NeuroMyoGène (INMG), team Chromatin Dynamics, Nuclear Domains, Virus F-69008, Lyon, France
| | - Patrick Lomonte
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR 5310, INSERM U 1217, LabEx DEVweCAN, Institut NeuroMyoGène (INMG), team Chromatin Dynamics, Nuclear Domains, Virus F-69008, Lyon, France
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91
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Lezaja A, Altmeyer M. Dealing with DNA lesions: When one cell cycle is not enough. Curr Opin Cell Biol 2020; 70:27-36. [PMID: 33310228 DOI: 10.1016/j.ceb.2020.11.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 11/02/2020] [Accepted: 11/05/2020] [Indexed: 02/07/2023]
Abstract
Subversion of genome integrity fuels cellular adaptation and is a prerequisite for organismal evolution, yet genomic lesions are also the harmful driving force of cancer and other age-related human diseases. Genome integrity maintenance is inherently linked to genome organization and nuclear architecture, which are substantially remodeled during the cell cycle. Here we discuss recent findings on how actively dividing cells cope with endogenous genomic lesions that occur frequently at repetitive, heterochromatic, and late replicating regions as byproducts of genome duplication. We discuss how such lesions, rather than being resolved immediately when they occur, are dealt with in subsequent cell cycle phases, and even after mitotic cell division, and how this in turn affects genome organization, stability, and function.
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Affiliation(s)
- Aleksandra Lezaja
- Department of Molecular Mechanisms of Disease, University of Zurich, Zurich, Switzerland
| | - Matthias Altmeyer
- Department of Molecular Mechanisms of Disease, University of Zurich, Zurich, Switzerland.
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92
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Alternative paths to telomere elongation. Semin Cell Dev Biol 2020; 113:88-96. [PMID: 33293233 DOI: 10.1016/j.semcdb.2020.11.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 10/31/2020] [Accepted: 11/09/2020] [Indexed: 11/24/2022]
Abstract
Overcoming cellular senescence that is induced by telomere shortening is critical in tumorigenesis. A majority of cancers achieve telomere maintenance through telomerase expression. However, a subset of cancers takes an alternate route for elongating telomeres: recombination-based alternative lengthening of telomeres (ALT). Current evidence suggests that break-induced replication (BIR), independent of RAD51, underlies ALT telomere synthesis. However, RAD51-dependent homologous recombination is required for homology search and inter-chromosomal telomere recombination in human ALT cancer cell maintenance. Accumulating evidence suggests that the breakdown of stalled replication forks, the replication stress, induces BIR at telomeres. Nevertheless, ALT research is still in its early stage and a comprehensive view is still unclear. Here, we review the current findings regarding the genesis of ALT, how this recombinant pathway is chosen, the epigenetic regulation of telomeres in ALT, and perspectives for clinical applications with the hope that this overview will generate new questions.
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93
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Dhar S, Datta A, Brosh RM. DNA helicases and their roles in cancer. DNA Repair (Amst) 2020; 96:102994. [PMID: 33137625 DOI: 10.1016/j.dnarep.2020.102994] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 09/28/2020] [Indexed: 12/15/2022]
Abstract
DNA helicases, known for their fundamentally important roles in genomic stability, are high profile players in cancer. Not only are there monogenic helicase disorders with a strong disposition to cancer, it is well appreciated that helicase variants are associated with specific cancers (e.g., breast cancer). Flipping the coin, DNA helicases are frequently overexpressed in cancerous tissues and reduction in helicase gene expression results in reduced proliferation and growth capacity, as well as DNA damage induction and apoptosis of cancer cells. The seminal roles of helicases in the DNA damage and replication stress responses, as well as DNA repair pathways, validate their vital importance in cancer biology and suggest their potential values as targets in anti-cancer therapy. In recent years, many laboratories have characterized the specialized roles of helicase to resolve transcription-replication conflicts, maintain telomeres, mediate cell cycle checkpoints, remodel stalled replication forks, and regulate transcription. In vivo models, particularly mice, have been used to interrogate helicase function and serve as a bridge for preclinical studies that may lead to novel therapeutic approaches. In this review, we will summarize our current knowledge of DNA helicases and their roles in cancer, emphasizing the latest developments.
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Affiliation(s)
- Srijita Dhar
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Arindam Datta
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Robert M Brosh
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA.
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94
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Mender I, Zhang A, Ren Z, Han C, Deng Y, Siteni S, Li H, Zhu J, Vemula A, Shay JW, Fu YX. Telomere Stress Potentiates STING-Dependent Anti-tumor Immunity. Cancer Cell 2020; 38:400-411.e6. [PMID: 32619407 PMCID: PMC7494563 DOI: 10.1016/j.ccell.2020.05.020] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 02/20/2020] [Accepted: 05/22/2020] [Indexed: 12/25/2022]
Abstract
Telomerase is an attractive target for anti-tumor therapy as it is almost universally expressed in cancer cells. Here, we show that treatment with a telomere-targeting drug, 6-thio-2'-deoxyguanosine (6-thio-dG), leads to tumor regression through innate and adaptive immune-dependent responses in syngeneic and humanized mouse models of telomerase-expressing cancers. 6-thio-dG treatment causes telomere-associated DNA damages that are sensed by dendritic cells (DCs) and activates the host cytosolic DNA sensing STING/interferon I pathway, resulting in enhanced cross-priming capacity of DCs and tumor-specific CD8+ T cell activation. Moreover, 6-thio-dG overcomes resistance to checkpoint blockade in advanced cancer models. Our results unveil how telomere stress increases innate sensing and adaptive anti-tumor immunity and provide strong rationales for combining telomere-targeting therapy with immunotherapy.
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Affiliation(s)
- Ilgen Mender
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Anli Zhang
- Department of Pathology, UT Southwestern Medical Center, Dallas, TX 75390, USA.
| | - Zhenhua Ren
- Department of Pathology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Chuanhui Han
- Department of Pathology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Yafang Deng
- Department of Pathology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Silvia Siteni
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Huiyu Li
- Hamon Center for Therapeutic Oncology Research, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Jiankun Zhu
- Department of Pathology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Aishwarya Vemula
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Jerry W Shay
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Yang-Xin Fu
- Department of Pathology, UT Southwestern Medical Center, Dallas, TX 75390, USA
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95
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Yan Y, Guo G, Huang J, Gao M, Zhu Q, Zeng S, Gong Z, Xu Z. Current understanding of extrachromosomal circular DNA in cancer pathogenesis and therapeutic resistance. J Hematol Oncol 2020; 13:124. [PMID: 32928268 PMCID: PMC7491193 DOI: 10.1186/s13045-020-00960-9] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 09/03/2020] [Indexed: 02/08/2023] Open
Abstract
Extrachromosomal circular DNA was recently found to be particularly abundant in multiple human cancer cells, although its frequency varies among different tumor types. Elevated levels of extrachromosomal circular DNA have been considered an effective biomarker of cancer pathogenesis. Multiple reports have demonstrated that the amplification of oncogenes and therapeutic resistance genes located on extrachromosomal DNA is a frequent event that drives intratumoral genetic heterogeneity and provides a potential evolutionary advantage. This review highlights the current understanding of the extrachromosomal circular DNA present in the tissues and circulation of patients with advanced cancers and provides a detailed discussion of their substantial roles in tumor regulation. Confirming the presence of cancer-related extrachromosomal circular DNA would provide a putative testing strategy for the precision diagnosis and treatment of human malignancies in clinical practice.
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Affiliation(s)
- Yuanliang Yan
- Department of Pharmacy, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China.,Department of Oncology, Mayo Clinic, Rochester, MN, 55905, USA
| | - Guijie Guo
- Department of Oncology, Mayo Clinic, Rochester, MN, 55905, USA
| | - Jinzhou Huang
- Department of Oncology, Mayo Clinic, Rochester, MN, 55905, USA
| | - Ming Gao
- Department of Oncology, Mayo Clinic, Rochester, MN, 55905, USA
| | - Qian Zhu
- Department of Oncology, Mayo Clinic, Rochester, MN, 55905, USA
| | - Shuangshuang Zeng
- Department of Pharmacy, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China
| | - Zhicheng Gong
- Department of Pharmacy, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China
| | - Zhijie Xu
- Department of Pathology, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China. .,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China.
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96
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Wassing IE, Esashi F. RAD51: Beyond the break. Semin Cell Dev Biol 2020; 113:38-46. [PMID: 32938550 PMCID: PMC8082279 DOI: 10.1016/j.semcdb.2020.08.010] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 08/14/2020] [Accepted: 08/28/2020] [Indexed: 01/30/2023]
Abstract
As the primary catalyst of homologous recombination (HR) in vertebrates, RAD51 has been extensively studied in the context of repair of double-stranded DNA breaks (DSBs). With recent advances in the understanding of RAD51 function extending beyond DSBs, the importance of RAD51 throughout DNA metabolism has become increasingly clear. Here we review the suggested roles of RAD51 beyond HR, specifically focusing on their interplay with DNA replication and the maintenance of genomic stability, in which RAD51 function emerges as a double-edged sword.
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Affiliation(s)
- Isabel E Wassing
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Fumiko Esashi
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK.
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97
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Miné-Hattab J, Chiolo I. Complex Chromatin Motions for DNA Repair. Front Genet 2020; 11:800. [PMID: 33061931 PMCID: PMC7481375 DOI: 10.3389/fgene.2020.00800] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 07/06/2020] [Indexed: 12/26/2022] Open
Abstract
A number of studies across different model systems revealed that chromatin undergoes significant changes in dynamics in response to DNA damage. These include local motion changes at damage sites, increased nuclear exploration of both damaged and undamaged loci, and directed motions to new nuclear locations associated with certain repair pathways. These studies also revealed the need for new analytical methods to identify directed motions in a context of mixed trajectories, and the importance of investigating nuclear dynamics over different time scales to identify diffusion regimes. Here we provide an overview of the current understanding of this field, including imaging and analytical methods developed to investigate nuclear dynamics in different contexts. These dynamics are essential for genome integrity. Identifying the molecular mechanisms responsible for these movements is key to understanding how their misregulation contributes to cancer and other genome instability disorders.
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Affiliation(s)
- Judith Miné-Hattab
- UMR 3664, CNRS, Institut Curie, PSL Research University, Paris, France
- UMR 3664, CNRS, Institut Curie, Sorbonne Université, Paris, France
| | - Irene Chiolo
- Molecular and Computational Biology Department, University of Southern California, Los Angeles, CA, United States
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98
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Abstract
The presence of actin in the nucleus has historically been a highly contentious issue. It is now, however, well accepted that actin has physiologically important roles in the nucleus. In this Review, we describe the evolution of our thinking about actin in the nucleus starting with evidence supporting its involvement in transcription, chromatin remodeling and intranuclear movements. We also review the growing literature on the mechanisms that regulate the import and export of actin and how post-translational modifications of actin could regulate nuclear actin. We end with an extended discussion of the role of nuclear actin in the repair of DNA double stranded breaks.
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Affiliation(s)
- Leonid Serebryannyy
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL 60612, United States
| | - Primal de Lanerolle
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL 60612, United States.
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99
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Frank L, Rippe K. Repetitive RNAs as Regulators of Chromatin-Associated Subcompartment Formation by Phase Separation. J Mol Biol 2020; 432:4270-4286. [DOI: 10.1016/j.jmb.2020.04.015] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 04/14/2020] [Accepted: 04/14/2020] [Indexed: 12/21/2022]
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100
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Zhang H, Zhao R, Tones J, Liu M, Dilley RL, Chenoweth DM, Greenberg RA, Lampson MA. Nuclear body phase separation drives telomere clustering in ALT cancer cells. Mol Biol Cell 2020; 31:2048-2056. [PMID: 32579423 PMCID: PMC7543070 DOI: 10.1091/mbc.e19-10-0589] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Telomerase-free cancer cells employ a recombination-based alternative lengthening of telomeres (ALT) pathway that depends on ALT-associated promyelocytic leukemia nuclear bodies (APBs), whose function is unclear. We find that APBs behave as liquid condensates in response to telomere DNA damage, suggesting two potential functions: condensation to enrich DNA repair factors and coalescence to cluster telomeres. To test these models, we developed a chemically induced dimerization approach to induce de novo APB condensation in live cells without DNA damage. We show that telomere-binding protein sumoylation nucleates APB condensation via interactions between small ubiquitin-like modifier (SUMO) and SUMO interaction motif (SIM), and that APB coalescence drives telomere clustering. The induced APBs lack DNA repair factors, indicating that APB functions in promoting telomere clustering can be uncoupled from enriching DNA repair factors. Indeed, telomere clustering relies only on liquid properties of the condensate, as an alternative condensation chemistry also induces clustering independent of sumoylation. Our findings introduce a chemical dimerization approach to manipulate phase separation and demonstrate how the material properties and chemical composition of APBs independently contribute to ALT, suggesting a general framework for how chromatin condensates promote cellular functions.
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Affiliation(s)
- Huaiying Zhang
- Departments of Biology, University of Pennsylvania, Philadelphia, PA 19104.,Departments of Chemistry, University of Pennsylvania, Philadelphia, PA 19104
| | - Rongwei Zhao
- Departments of Chemistry, University of Pennsylvania, Philadelphia, PA 19104
| | - Jason Tones
- Departments of Chemistry, University of Pennsylvania, Philadelphia, PA 19104
| | - Michel Liu
- Departments of Biology, University of Pennsylvania, Philadelphia, PA 19104
| | - Robert L Dilley
- Penn Center for Genome Integrity, University of Pennsylvania, Philadelphia, PA 19104
| | - David M Chenoweth
- Department of Cancer Biology, Basser Center for BRCA, Perelman School of Medicine
| | - Roger A Greenberg
- Penn Center for Genome Integrity, University of Pennsylvania, Philadelphia, PA 19104
| | - Michael A Lampson
- Penn Center for Genome Integrity, University of Pennsylvania, Philadelphia, PA 19104
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