1
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Mateo-Bonmatí E, Montez M, Maple R, Fiedler M, Fang X, Saalbach G, Passmore LA, Dean C. A CPF-like phosphatase module links transcription termination to chromatin silencing. Mol Cell 2024; 84:2272-2286.e7. [PMID: 38851185 DOI: 10.1016/j.molcel.2024.05.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 02/28/2024] [Accepted: 05/15/2024] [Indexed: 06/10/2024]
Abstract
The interconnections between co-transcriptional regulation, chromatin environment, and transcriptional output remain poorly understood. Here, we investigate the mechanism underlying RNA 3' processing-mediated Polycomb silencing of Arabidopsis FLOWERING LOCUS C (FLC). We show a requirement for ANTHESIS PROMOTING FACTOR 1 (APRF1), a homolog of yeast Swd2 and human WDR82, known to regulate RNA polymerase II (RNA Pol II) during transcription termination. APRF1 interacts with TYPE ONE SERINE/THREONINE PROTEIN PHOSPHATASE 4 (TOPP4) (yeast Glc7/human PP1) and LUMINIDEPENDENS (LD), the latter showing structural features found in Ref2/PNUTS, all components of the yeast and human phosphatase module of the CPF 3' end-processing machinery. LD has been shown to co-associate in vivo with the histone H3 K4 demethylase FLOWERING LOCUS D (FLD). This work shows how the APRF1/LD-mediated polyadenylation/termination process influences subsequent rounds of transcription by changing the local chromatin environment at FLC.
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Affiliation(s)
- Eduardo Mateo-Bonmatí
- Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK; Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM), Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA)/CSIC, Pozuelo de Alarcón, Madrid 28223, Spain.
| | - Miguel Montez
- Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK
| | - Robert Maple
- Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK
| | - Marc Fiedler
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | - Xiaofeng Fang
- Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK
| | - Gerhard Saalbach
- Biological Chemistry, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK
| | | | - Caroline Dean
- Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK; MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK.
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2
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Milano L, Gautam A, Caldecott KW. DNA damage and transcription stress. Mol Cell 2024; 84:70-79. [PMID: 38103560 DOI: 10.1016/j.molcel.2023.11.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 11/10/2023] [Accepted: 11/15/2023] [Indexed: 12/19/2023]
Abstract
Genome damage and transcription are intimately linked. Tens to hundreds of thousands of DNA lesions arise in each cell each day, many of which can directly or indirectly impede transcription. Conversely, the process of gene expression is itself a source of endogenous DNA lesions as a result of the susceptibility of single-stranded DNA to damage, conflicts with the DNA replication machinery, and engagement by cells of topoisomerases and base excision repair enzymes to regulate the initiation and progression of gene transcription. Although such processes are tightly regulated and normally accurate, on occasion, they can become abortive and leave behind DNA breaks that can drive genome rearrangements, instability, or cell death.
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Affiliation(s)
- Larissa Milano
- Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton BN1 9RQ, UK.
| | - Amit Gautam
- Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton BN1 9RQ, UK.
| | - Keith W Caldecott
- Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton BN1 9RQ, UK.
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3
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Kumar C, Remus D. Looping out of control: R-loops in transcription-replication conflict. Chromosoma 2024; 133:37-56. [PMID: 37419963 PMCID: PMC10771546 DOI: 10.1007/s00412-023-00804-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 06/27/2023] [Accepted: 06/28/2023] [Indexed: 07/09/2023]
Abstract
Transcription-replication conflict is a major cause of replication stress that arises when replication forks collide with the transcription machinery. Replication fork stalling at sites of transcription compromises chromosome replication fidelity and can induce DNA damage with potentially deleterious consequences for genome stability and organismal health. The block to DNA replication by the transcription machinery is complex and can involve stalled or elongating RNA polymerases, promoter-bound transcription factor complexes, or DNA topology constraints. In addition, studies over the past two decades have identified co-transcriptional R-loops as a major source for impairment of DNA replication forks at active genes. However, how R-loops impede DNA replication at the molecular level is incompletely understood. Current evidence suggests that RNA:DNA hybrids, DNA secondary structures, stalled RNA polymerases, and condensed chromatin states associated with R-loops contribute to the of fork progression. Moreover, since both R-loops and replication forks are intrinsically asymmetric structures, the outcome of R-loop-replisome collisions is influenced by collision orientation. Collectively, the data suggest that the impact of R-loops on DNA replication is highly dependent on their specific structural composition. Here, we will summarize our current understanding of the molecular basis for R-loop-induced replication fork progression defects.
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Affiliation(s)
- Charanya Kumar
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York, 10065, USA
| | - Dirk Remus
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York, 10065, USA.
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4
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Russo M, Piccolo V, Polizzese D, Prosperini E, Borriero C, Polletti S, Bedin F, Marenda M, Michieletto D, Mandana GM, Rodighiero S, Cuomo A, Natoli G. Restrictor synergizes with Symplekin and PNUTS to terminate extragenic transcription. Genes Dev 2023; 37:1017-1040. [PMID: 38092518 PMCID: PMC10760643 DOI: 10.1101/gad.351057.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Accepted: 11/29/2023] [Indexed: 12/28/2023]
Abstract
Transcription termination pathways mitigate the detrimental consequences of unscheduled promiscuous initiation occurring at hundreds of thousands of genomic cis-regulatory elements. The Restrictor complex, composed of the Pol II-interacting protein WDR82 and the RNA-binding protein ZC3H4, suppresses processive transcription at thousands of extragenic sites in mammalian genomes. Restrictor-driven termination does not involve nascent RNA cleavage, and its interplay with other termination machineries is unclear. Here we show that efficient termination at Restrictor-controlled extragenic transcription units involves the recruitment of the protein phosphatase 1 (PP1) regulatory subunit PNUTS, a negative regulator of the SPT5 elongation factor, and Symplekin, a protein associated with RNA cleavage complexes but also involved in cleavage-independent and phosphatase-dependent termination of noncoding RNAs in yeast. PNUTS and Symplekin act synergistically with, but independently from, Restrictor to dampen processive extragenic transcription. Moreover, the presence of limiting nuclear levels of Symplekin imposes a competition for its recruitment among multiple transcription termination machineries, resulting in mutual regulatory interactions. Hence, by synergizing with Restrictor, Symplekin and PNUTS enable efficient termination of processive, long-range extragenic transcription.
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Affiliation(s)
- Marta Russo
- Department of Experimental Oncology, European Institute of Oncology (IEO), Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Milan I-20139, Italy
| | - Viviana Piccolo
- Department of Experimental Oncology, European Institute of Oncology (IEO), Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Milan I-20139, Italy
| | - Danilo Polizzese
- Department of Experimental Oncology, European Institute of Oncology (IEO), Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Milan I-20139, Italy
| | - Elena Prosperini
- Department of Experimental Oncology, European Institute of Oncology (IEO), Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Milan I-20139, Italy
| | - Carolina Borriero
- Department of Experimental Oncology, European Institute of Oncology (IEO), Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Milan I-20139, Italy
| | - Sara Polletti
- Department of Experimental Oncology, European Institute of Oncology (IEO), Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Milan I-20139, Italy
| | - Fabio Bedin
- Department of Experimental Oncology, European Institute of Oncology (IEO), Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Milan I-20139, Italy
| | - Mattia Marenda
- Department of Experimental Oncology, European Institute of Oncology (IEO), Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Milan I-20139, Italy
| | - Davide Michieletto
- School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3FD, United Kingdom
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh EH4 2XU, United Kingdom
| | - Gaurav Madappa Mandana
- Department of Experimental Oncology, European Institute of Oncology (IEO), Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Milan I-20139, Italy
| | - Simona Rodighiero
- Department of Experimental Oncology, European Institute of Oncology (IEO), Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Milan I-20139, Italy
| | - Alessandro Cuomo
- Department of Experimental Oncology, European Institute of Oncology (IEO), Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Milan I-20139, Italy
| | - Gioacchino Natoli
- Department of Experimental Oncology, European Institute of Oncology (IEO), Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Milan I-20139, Italy;
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5
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Heuzé J, Kemiha S, Barthe A, Vilarrubias AT, Aouadi E, Aiello U, Libri D, Lin Y, Lengronne A, Poli J, Pasero P. RNase H2 degrades toxic RNA:DNA hybrids behind stalled forks to promote replication restart. EMBO J 2023; 42:e113104. [PMID: 37855233 PMCID: PMC10690446 DOI: 10.15252/embj.2022113104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Revised: 09/27/2023] [Accepted: 10/04/2023] [Indexed: 10/20/2023] Open
Abstract
R-loops represent a major source of replication stress, but the mechanism by which these structures impede fork progression remains unclear. To address this question, we monitored fork progression, arrest, and restart in Saccharomyces cerevisiae cells lacking RNase H1 and H2, two enzymes responsible for degrading RNA:DNA hybrids. We found that while RNase H-deficient cells could replicate their chromosomes normally under unchallenged growth conditions, their replication was impaired when exposed to hydroxyurea (HU) or methyl methanesulfonate (MMS). Treated cells exhibited increased levels of RNA:DNA hybrids at stalled forks and were unable to generate RPA-coated single-stranded (ssDNA), an important postreplicative intermediate in resuming replication. Similar impairments in nascent DNA resection and ssDNA formation at HU-arrested forks were observed in human cells lacking RNase H2. However, fork resection was fully restored by addition of triptolide, an inhibitor of transcription that induces RNA polymerase degradation. Taken together, these data indicate that RNA:DNA hybrids not only act as barriers to replication forks, but also interfere with postreplicative fork repair mechanisms if not promptly degraded by RNase H.
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Affiliation(s)
- Jonathan Heuzé
- Institut de Génétique HumaineUniversité de Montpellier, CNRS, Equipe labélisée Ligue contre le CancerMontpellierFrance
| | - Samira Kemiha
- Institut de Génétique HumaineUniversité de Montpellier, CNRS, Equipe labélisée Ligue contre le CancerMontpellierFrance
| | - Antoine Barthe
- Institut de Génétique HumaineUniversité de Montpellier, CNRS, Equipe labélisée Ligue contre le CancerMontpellierFrance
| | - Alba Torán Vilarrubias
- Institut de Génétique HumaineUniversité de Montpellier, CNRS, Equipe labélisée Ligue contre le CancerMontpellierFrance
| | - Elyès Aouadi
- Institut de Génétique HumaineUniversité de Montpellier, CNRS, Equipe labélisée Ligue contre le CancerMontpellierFrance
| | - Umberto Aiello
- Université Paris Cité, CNRS, Institut Jacques MonodParisFrance
- Department of GeneticsStanford UniversityStanfordCAUSA
| | - Domenico Libri
- Université Paris Cité, CNRS, Institut Jacques MonodParisFrance
- Present address:
Institut de Génétique Moléculaire de MontpellierUniversité de Montpellier, CNRSMontpellierFrance
| | - Yea‐Lih Lin
- Institut de Génétique HumaineUniversité de Montpellier, CNRS, Equipe labélisée Ligue contre le CancerMontpellierFrance
| | - Armelle Lengronne
- Institut de Génétique HumaineUniversité de Montpellier, CNRS, Equipe labélisée Ligue contre le CancerMontpellierFrance
| | - Jérôme Poli
- Institut de Génétique HumaineUniversité de Montpellier, CNRS, Equipe labélisée Ligue contre le CancerMontpellierFrance
- Institut Universitaire de France (IUF)ParisFrance
| | - Philippe Pasero
- Institut de Génétique HumaineUniversité de Montpellier, CNRS, Equipe labélisée Ligue contre le CancerMontpellierFrance
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6
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Abstract
Transcription and replication both require large macromolecular complexes to act on a DNA template, yet these machineries cannot simultaneously act on the same DNA sequence. Conflicts between the replication and transcription machineries (transcription-replication conflicts, or TRCs) are widespread in both prokaryotes and eukaryotes and have the capacity to both cause DNA damage and compromise complete, faithful replication of the genome. This review will highlight recent studies investigating the genomic locations of TRCs and the mechanisms by which they may be prevented, mitigated, or resolved. We address work from both model organisms and mammalian systems but predominantly focus on multicellular eukaryotes owing to the additional complexities inherent in the coordination of replication and transcription in the context of cell type-specific gene expression and higher-order chromatin organization.
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Affiliation(s)
- Liana Goehring
- Department of Biochemistry & Molecular Pharmacology, New York University School of Medicine, New York, NY, USA;
| | - Tony T Huang
- Department of Biochemistry & Molecular Pharmacology, New York University School of Medicine, New York, NY, USA;
| | - Duncan J Smith
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, NY, USA;
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7
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Heuzé J, Lin YL, Lengronne A, Poli J, Pasero P. Impact of R-loops on oncogene-induced replication stress in cancer cells. C R Biol 2023; 346:95-105. [PMID: 37779381 DOI: 10.5802/crbiol.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 07/19/2023] [Accepted: 07/20/2023] [Indexed: 10/03/2023]
Abstract
Replication stress is an alteration in the progression of replication forks caused by a variety of events of endogenous or exogenous origin. In precancerous lesions, this stress is exacerbated by the deregulation of oncogenic pathways, which notably disrupts the coordination between replication and transcription, and leads to genetic instability and cancer development. It is now well established that transcription can interfere with genome replication in different ways, such as head-on collisions between polymerases, accumulation of positive DNA supercoils or formation of R-loops. These structures form during transcription when nascent RNA reanneals with DNA behind the RNA polymerase, forming a stable DNA:RNA hybrid. In this review, we discuss how these different cotranscriptional processes disrupt the progression of replication forks and how they contribute to genetic instability in cancer cells.
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8
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Cui G, Zhou J, Sun J, Kou X, Su Z, Xu Y, Liu T, Sun L, Li W, Wu X, Wei Q, Gao S, Shi K. WD repeat domain 82 (Wdr82) facilitates mouse iPSCs generation by interfering mitochondrial oxidative phosphorylation and glycolysis. Cell Mol Life Sci 2023; 80:218. [PMID: 37470863 PMCID: PMC10359378 DOI: 10.1007/s00018-023-04871-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2023] [Revised: 07/01/2023] [Accepted: 07/10/2023] [Indexed: 07/21/2023]
Abstract
BACKGROUND Abundantly expressed factors in the oocyte cytoplasm can remarkably reprogram terminally differentiated germ cells or somatic cells into totipotent state within a short time. However, the mechanism of the different factors underlying the reprogramming process remains uncertain. METHODS On the basis of Yamanaka factors OSKM induction method, MEF cells were induced and reprogrammed into iPSCs under conditions of the oocyte-derived factor Wdr82 overexpression and/or knockdown, so as to assess the reprogramming efficiency. Meanwhile, the cellular metabolism was monitored and evaluated during the reprogramming process. The plurpotency of the generated iPSCs was confirmed via pluripotent gene expression detection, embryoid body differentiation and chimeric mouse experiment. RESULTS Here, we show that the oocyte-derived factor Wdr82 promotes the efficiency of MEF reprogramming into iPSCs to a greater degree than the Yamanaka factors OSKM. The Wdr82-expressing iPSC line showed pluripotency to differentiate and transmit genetic material to chimeric offsprings. In contrast, the knocking down of Wdr82 can significantly reduce the efficiency of somatic cell reprogramming. We further demonstrate that the significant suppression of oxidative phosphorylation in mitochondria underlies the molecular mechanism by which Wdr82 promotes the efficiency of somatic cell reprogramming. Our study suggests a link between mitochondrial energy metabolism remodeling and cell fate transition or stem cell function maintenance, which might shed light on the embryonic development and stem cell biology.
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Affiliation(s)
- Guina Cui
- Key Laboratory of Animal Bioengineering and Disease Prevention of Shandong Province, College of Animal Science and Technology, Shandong Agricultural University, No. 61 Daizong Street, Taian, 271018, China
- Clinical and Translational Research Center of Shanghai First Maternity and Infant Hospital, Frontier Science Center for Stem Cell Research, School of Life Sciences and Technology, Tongji University, Shanghai, 200092, China
| | - Jingxuan Zhou
- Key Laboratory of Animal Bioengineering and Disease Prevention of Shandong Province, College of Animal Science and Technology, Shandong Agricultural University, No. 61 Daizong Street, Taian, 271018, China
| | - Jiatong Sun
- Key Laboratory of Animal Bioengineering and Disease Prevention of Shandong Province, College of Animal Science and Technology, Shandong Agricultural University, No. 61 Daizong Street, Taian, 271018, China
- Clinical and Translational Research Center of Shanghai First Maternity and Infant Hospital, Frontier Science Center for Stem Cell Research, School of Life Sciences and Technology, Tongji University, Shanghai, 200092, China
| | - Xiaochen Kou
- Clinical and Translational Research Center of Shanghai First Maternity and Infant Hospital, Frontier Science Center for Stem Cell Research, School of Life Sciences and Technology, Tongji University, Shanghai, 200092, China
| | - Zhongqu Su
- Key Laboratory of Animal Bioengineering and Disease Prevention of Shandong Province, College of Animal Science and Technology, Shandong Agricultural University, No. 61 Daizong Street, Taian, 271018, China
- Clinical and Translational Research Center of Shanghai First Maternity and Infant Hospital, Frontier Science Center for Stem Cell Research, School of Life Sciences and Technology, Tongji University, Shanghai, 200092, China
| | - Yiliang Xu
- Key Laboratory of Animal Bioengineering and Disease Prevention of Shandong Province, College of Animal Science and Technology, Shandong Agricultural University, No. 61 Daizong Street, Taian, 271018, China
- Clinical and Translational Research Center of Shanghai First Maternity and Infant Hospital, Frontier Science Center for Stem Cell Research, School of Life Sciences and Technology, Tongji University, Shanghai, 200092, China
| | - Tingjun Liu
- Key Laboratory of Animal Bioengineering and Disease Prevention of Shandong Province, College of Animal Science and Technology, Shandong Agricultural University, No. 61 Daizong Street, Taian, 271018, China
| | - Lili Sun
- Key Laboratory of Animal Bioengineering and Disease Prevention of Shandong Province, College of Animal Science and Technology, Shandong Agricultural University, No. 61 Daizong Street, Taian, 271018, China
| | - Wenhui Li
- Key Laboratory of Animal Bioengineering and Disease Prevention of Shandong Province, College of Animal Science and Technology, Shandong Agricultural University, No. 61 Daizong Street, Taian, 271018, China
| | - Xuanning Wu
- Key Laboratory of Animal Bioengineering and Disease Prevention of Shandong Province, College of Animal Science and Technology, Shandong Agricultural University, No. 61 Daizong Street, Taian, 271018, China
| | - Qingqing Wei
- Key Laboratory of Animal Bioengineering and Disease Prevention of Shandong Province, College of Animal Science and Technology, Shandong Agricultural University, No. 61 Daizong Street, Taian, 271018, China
| | - Shaorong Gao
- Clinical and Translational Research Center of Shanghai First Maternity and Infant Hospital, Frontier Science Center for Stem Cell Research, School of Life Sciences and Technology, Tongji University, Shanghai, 200092, China.
| | - Kerong Shi
- Key Laboratory of Animal Bioengineering and Disease Prevention of Shandong Province, College of Animal Science and Technology, Shandong Agricultural University, No. 61 Daizong Street, Taian, 271018, China.
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9
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Bhowmick R, Mehta KPM, Lerdrup M, Cortez D. Integrator facilitates RNAPII removal to prevent transcription-replication collisions and genome instability. Mol Cell 2023; 83:2357-2366.e8. [PMID: 37295432 PMCID: PMC10330747 DOI: 10.1016/j.molcel.2023.05.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 04/17/2023] [Accepted: 05/10/2023] [Indexed: 06/12/2023]
Abstract
DNA replication preferentially initiates close to active transcription start sites (TSSs) in the human genome. Transcription proceeds discontinuously with an accumulation of RNA polymerase II (RNAPII) in a paused state near the TSS. Consequently, replication forks inevitably encounter paused RNAPII soon after replication initiates. Hence, dedicated machinery may be needed to remove RNAPII and facilitate unperturbed fork progression. In this study, we discovered that Integrator, a transcription termination machinery involved in the processing of RNAPII transcripts, interacts with the replicative helicase at active forks and promotes the removal of RNAPII from the path of the replication fork. Integrator-deficient cells have impaired replication fork progression and accumulate hallmarks of genome instability including chromosome breaks and micronuclei. The Integrator complex resolves co-directional transcription-replication conflicts to facilitate faithful DNA replication.
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Affiliation(s)
- Rahul Bhowmick
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37237, USA.
| | - Kavi P M Mehta
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37237, USA
| | - Mads Lerdrup
- Center for Chromosome Stability, Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, 2200 Copenhagen, Denmark
| | - David Cortez
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37237, USA.
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10
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Wang T, Zhao R, Zhi J, Liu Z, Wu A, Yang Z, Wang W, Ni T, Jing L, Yu M. Tox4 regulates transcriptional elongation and reinitiation during murine T cell development. Commun Biol 2023; 6:613. [PMID: 37286708 DOI: 10.1038/s42003-023-04992-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2022] [Accepted: 05/30/2023] [Indexed: 06/09/2023] Open
Abstract
HMG protein Tox4 is a regulator of PP1 phosphatases with unknown function in development. Here we show that Tox4 conditional knockout in mice reduces thymic cellularity, partially blocks T cell development, and decreases ratio of CD8 to CD4 through decreasing proliferation and increasing apoptosis of CD8 cells. In addition, single-cell RNA-seq discovered that Tox4 loss also impairs proliferation of the fast-proliferating double positive (DP) blast population within DP cells in part due to downregulation of genes critical for proliferation, notably Cdk1. Moreover, genes with high and low expression level are more dependent on Tox4 than genes with medium expression level. Mechanistically, Tox4 may facilitate transcriptional reinitiation and restrict elongation in a dephosphorylation-dependent manner, a mechanism that is conserved between mouse and human. These results provide insights into the role of TOX4 in development and establish it as an evolutionarily conserved regulator of transcriptional elongation and reinitiation.
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Affiliation(s)
- Talang Wang
- Sheng Yushou Center of Cell Biology and Immunology, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Ruoyu Zhao
- Sheng Yushou Center of Cell Biology and Immunology, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
- Department of Pathology, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, 200052, China
| | - Junhong Zhi
- Sheng Yushou Center of Cell Biology and Immunology, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Ziling Liu
- Sheng Yushou Center of Cell Biology and Immunology, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Aiwei Wu
- Sheng Yushou Center of Cell Biology and Immunology, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Zimei Yang
- Sheng Yushou Center of Cell Biology and Immunology, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
- School of Pharmacy, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Weixu Wang
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Human Phenome Institute, Shanghai Engineering Research Center of Industrial Microorganisms, School of Life Sciences and Huashan Hospital, Fudan University, Shanghai, 200438, China
| | - Ting Ni
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Human Phenome Institute, Shanghai Engineering Research Center of Industrial Microorganisms, School of Life Sciences and Huashan Hospital, Fudan University, Shanghai, 200438, China
| | - Lili Jing
- School of Pharmacy, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Ming Yu
- Sheng Yushou Center of Cell Biology and Immunology, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China.
- Department of Pathology, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, 200052, China.
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11
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Spencley AL, Bar S, Swigut T, Flynn RA, Lee CH, Chen LF, Bassik MC, Wysocka J. Co-transcriptional genome surveillance by HUSH is coupled to termination machinery. Mol Cell 2023; 83:1623-1639.e8. [PMID: 37164018 PMCID: PMC10915761 DOI: 10.1016/j.molcel.2023.04.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 01/12/2023] [Accepted: 04/12/2023] [Indexed: 05/12/2023]
Abstract
The HUSH complex recognizes and silences foreign DNA such as viruses, transposons, and transgenes without prior exposure to its targets. Here, we show that endogenous targets of the HUSH complex fall into two distinct classes based on the presence or absence of H3K9me3. These classes are further distinguished by their transposon content and differential response to the loss of HUSH. A de novo genomic rearrangement at the Sox2 locus induces a switch from H3K9me3-independent to H3K9me3-associated HUSH targeting, resulting in silencing. We further demonstrate that HUSH interacts with the termination factor WDR82 and-via its component MPP8-with nascent RNA. HUSH accumulates at sites of high RNAPII occupancy including long exons and transcription termination sites in a manner dependent on WDR82 and CPSF. Together, our results uncover the functional diversity of HUSH targets and show that this vertebrate-specific complex exploits evolutionarily ancient transcription termination machinery for co-transcriptional chromatin targeting and genome surveillance.
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Affiliation(s)
- Andrew L Spencley
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, USA; Cancer Biology Program, Stanford University School of Medicine, Stanford, CA, USA
| | - Shiran Bar
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Tomek Swigut
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Ryan A Flynn
- Stem Cell Program, Boston Children's Hospital, Boston, MA, USA; Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA, USA
| | - Cameron H Lee
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
| | - Liang-Fu Chen
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Michael C Bassik
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
| | - Joanna Wysocka
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, USA; Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA; Institute of Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, USA; Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA, USA.
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12
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Bao S, Xu C. Molecular insight into the SETD1A/B N-terminal region and its interaction with WDR82. Biochem Biophys Res Commun 2023; 658:136-140. [PMID: 37030068 DOI: 10.1016/j.bbrc.2023.03.064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2023] [Accepted: 03/27/2023] [Indexed: 04/03/2023]
Abstract
SETD1A and SETD1B originate from Set1, the sole H3K4 methyltransferase in yeast, and they play important roles in active gene transcription. Here, we present the crystal structures of the RRM domains of human SETD1A and SETD1B. Although both RRM domains adopt a canonical RRM fold, their structural features are different from that of the yeast Set1 RRM domain, their yeast homolog. By using an ITC binding assay, we found an intrinsically disordered region in SETD1A/B binds WDR82. The structural analysis implies that the positively charged regions within human RRM domains might be involved in binding to RNA. Our work provides structural insight into the assembly of WDR82 with the catalytic subunits SETD1A/B in the context of the whole complex.
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13
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The TFIIS N-terminal domain (TND): a transcription assembly module at the interface of order and disorder. Biochem Soc Trans 2023; 51:125-135. [PMID: 36651856 PMCID: PMC9987994 DOI: 10.1042/bst20220342] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 12/22/2022] [Accepted: 01/03/2023] [Indexed: 01/19/2023]
Abstract
Interaction scaffolds that selectively recognize disordered protein strongly shape protein interactomes. An important scaffold of this type that contributes to transcription is the TFIIS N-terminal domain (TND). The TND is a five-helical bundle that has no known enzymatic activity, but instead selectively reads intrinsically disordered sequences of other proteins. Here, we review the structural and functional properties of TNDs and their cognate disordered ligands known as TND-interacting motifs (TIMs). TNDs or TIMs are found in prominent members of the transcription machinery, including TFIIS, super elongation complex, SWI/SNF, Mediator, IWS1, SPT6, PP1-PNUTS phosphatase, elongin, H3K36me3 readers, the transcription factor MYC, and others. We also review how the TND interactome contributes to the regulation of transcription. Because the TND is the most significantly enriched fold among transcription elongation regulators, TND- and TIM-driven interactions have widespread roles in the regulation of many transcriptional processes.
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14
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The PNUTS-PP1 complex acts as an intrinsic barrier to herpesvirus KSHV gene expression and replication. Nat Commun 2022; 13:7447. [PMID: 36460671 PMCID: PMC9718767 DOI: 10.1038/s41467-022-35268-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 11/24/2022] [Indexed: 12/03/2022] Open
Abstract
Control of RNA Polymerase II (pol II) elongation is a critical component of gene expression in mammalian cells. The PNUTS-PP1 complex controls elongation rates, slowing pol II after polyadenylation sites to promote termination. The Kaposi's sarcoma-associated herpesvirus (KSHV) co-opts pol II to express its genes, but little is known about its regulation of pol II elongation. We identified PNUTS as a suppressor of a KSHV reporter gene in a genome-wide CRISPR screen. PNUTS depletion enhances global KSHV gene expression and overall viral replication. Mechanistically, PNUTS requires PP1 interaction, binds viral RNAs downstream of polyadenylation sites, and restricts transcription readthrough of viral genes. Surprisingly, PNUTS also represses productive elongation at the 5´ ends of the KSHV reporter and the KSHV T1.4 RNA. From these data, we conclude that PNUTS' activity constitutes an intrinsic barrier to KSHV replication likely by suppressing pol II elongation at promoter-proximal regions.
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15
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Zhang FL, Li DQ. Targeting Chromatin-Remodeling Factors in Cancer Cells: Promising Molecules in Cancer Therapy. Int J Mol Sci 2022; 23:12815. [PMID: 36361605 PMCID: PMC9655648 DOI: 10.3390/ijms232112815] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 10/12/2022] [Accepted: 10/19/2022] [Indexed: 03/28/2024] Open
Abstract
ATP-dependent chromatin-remodeling complexes can reorganize and remodel chromatin and thereby act as important regulator in various cellular processes. Based on considerable studies over the past two decades, it has been confirmed that the abnormal function of chromatin remodeling plays a pivotal role in genome reprogramming for oncogenesis in cancer development and/or resistance to cancer therapy. Recently, exciting progress has been made in the identification of genetic alteration in the genes encoding the chromatin-remodeling complexes associated with tumorigenesis, as well as in our understanding of chromatin-remodeling mechanisms in cancer biology. Here, we present preclinical evidence explaining the signaling mechanisms involving the chromatin-remodeling misregulation-induced cancer cellular processes, including DNA damage signaling, metastasis, angiogenesis, immune signaling, etc. However, even though the cumulative evidence in this field provides promising emerging molecules for therapeutic explorations in cancer, more research is needed to assess the clinical roles of these genetic cancer targets.
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Affiliation(s)
- Fang-Lin Zhang
- Shanghai Cancer Center and Institutes of Biomedical Sciences, Shanghai Medical College, Fudan University, Shanghai 200032, China
- Cancer Institute, Shanghai Medical College, Fudan University, Shanghai 200032, China
- Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Da-Qiang Li
- Shanghai Cancer Center and Institutes of Biomedical Sciences, Shanghai Medical College, Fudan University, Shanghai 200032, China
- Cancer Institute, Shanghai Medical College, Fudan University, Shanghai 200032, China
- Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China
- Department of Breast Surgery, Shanghai Medical College, Fudan University, Shanghai 200032, China
- Shanghai Key Laboratory of Breast Cancer, Shanghai Medical College, Fudan University, Shanghai 200032, China
- Shanghai Key Laboratory of Radiation Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China
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16
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Gulyas L, Glaunsinger BA. RNA polymerase II subunit modulation during viral infection and cellular stress. Curr Opin Virol 2022; 56:101259. [PMID: 36162260 PMCID: PMC10150648 DOI: 10.1016/j.coviro.2022.101259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 08/10/2022] [Accepted: 08/15/2022] [Indexed: 11/03/2022]
Abstract
Control of gene expression, including transcription, is central in dictating the outcome of viral infection. One of the profound alterations induced by viruses is modification to the integrity and function of eukaryotic RNA polymerase II (Pol II). Here, we discuss how infection perturbs the Pol II complex by altering subunit phosphorylation and turnover, as well as how cellular genotoxic stress (e.g. DNA damage) elicits similar outcomes. By highlighting emerging parallels and differences in Pol II control during viral infection and abiotic stress, we hope to bolster identification of pathways that target Pol II and regulate the transcriptome.
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Affiliation(s)
- Leah Gulyas
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA
| | - Britt A Glaunsinger
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA; Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA; Howard Hughes Medical Institute, University of California, Berkeley, CA 94709, USA.
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17
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Bay LTE, Syljuåsen RG, Landsverk HB. A novel, rapid and sensitive flow cytometry method reveals degradation of promoter proximal paused RNAPII in the presence and absence of UV. Nucleic Acids Res 2022; 50:e89. [PMID: 35641102 PMCID: PMC9410883 DOI: 10.1093/nar/gkac434] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 04/08/2022] [Accepted: 05/11/2022] [Indexed: 12/17/2022] Open
Abstract
RNA polymerase II (RNAPII) is emerging as an important factor in DNA damage responses, but how it responds to genotoxic stress is not fully understood. We have developed a rapid and sensitive flow cytometry method to study chromatin binding of RNAPII in individual human cells through the cell cycle. Indicating enhanced transcription initiation at early timepoints, levels of RNAPII were increased at 15–30min after UV-induced DNA damage. This was particularly evident for the S5 phosphorylated form of RNAPII (pRNAPII S5), which is typically associated with promoter proximal pausing. Furthermore, degradation of pRNAPII S5 frequently occurs, as its levels on chromatin were strongly enhanced by the proteasome inhibitor MG132 with and without UV. Remarkably, inhibiting pause release with 5,6-dichloro-1-beta-ribo-furanosyl benzimidazole (DRB) further promoted UV-induced degradation of pRNAPII S5, suggesting enhanced initiation may lead to a phenomenon of ‘promoter proximal crowding’ resulting in premature termination via degradation of RNAPII. Moreover, pRNAPII S2 levels on chromatin were more stable in S phase of the cell cycle 2h after UV, indicating cell cycle specific effects. Altogether our results demonstrate a useful new method and suggest that degradation of promoter proximal RNAPII plays an unanticipated large role both during normal transcription and after UV.
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Affiliation(s)
- Lilli T E Bay
- Department of Radiation Biology, Institute for Cancer Research, Norwegian Radium Hospital, Oslo University Hospital, 0379 Oslo, Norway
| | - Randi G Syljuåsen
- Department of Radiation Biology, Institute for Cancer Research, Norwegian Radium Hospital, Oslo University Hospital, 0379 Oslo, Norway
| | - Helga B Landsverk
- Department of Radiation Biology, Institute for Cancer Research, Norwegian Radium Hospital, Oslo University Hospital, 0379 Oslo, Norway
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18
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Brickner JR, Garzon JL, Cimprich KA. Walking a tightrope: The complex balancing act of R-loops in genome stability. Mol Cell 2022; 82:2267-2297. [PMID: 35508167 DOI: 10.1016/j.molcel.2022.04.014] [Citation(s) in RCA: 81] [Impact Index Per Article: 40.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 03/28/2022] [Accepted: 04/10/2022] [Indexed: 12/14/2022]
Abstract
Although transcription is an essential cellular process, it is paradoxically also a well-recognized cause of genomic instability. R-loops, non-B DNA structures formed when nascent RNA hybridizes to DNA to displace the non-template strand as single-stranded DNA (ssDNA), are partially responsible for this instability. Yet, recent work has begun to elucidate regulatory roles for R-loops in maintaining the genome. In this review, we discuss the cellular contexts in which R-loops contribute to genomic instability, particularly during DNA replication and double-strand break (DSB) repair. We also summarize the evidence that R-loops participate as an intermediate during repair and may influence pathway choice to preserve genomic integrity. Finally, we discuss the immunogenic potential of R-loops and highlight their links to disease should they become pathogenic.
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Affiliation(s)
- Joshua R Brickner
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Jada L Garzon
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Karlene A Cimprich
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305, USA.
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19
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Park K, Zhong J, Jang JS, Kim J, Kim HJ, Lee JH, Kim J. ZWC complex-mediated SPT5 phosphorylation suppresses divergent antisense RNA transcription at active gene promoters. Nucleic Acids Res 2022; 50:3835-3851. [PMID: 35325203 PMCID: PMC9023261 DOI: 10.1093/nar/gkac193] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 03/08/2022] [Accepted: 03/13/2022] [Indexed: 11/14/2022] Open
Abstract
The human genome encodes large numbers of non-coding RNAs, including divergent antisense transcripts at transcription start sites (TSSs). However, molecular mechanisms by which divergent antisense transcription is regulated have not been detailed. Here, we report a novel ZWC complex composed of ZC3H4, WDR82 and CK2 that suppresses divergent antisense transcription. The ZWC complex preferentially localizes at TSSs of active genes through direct interactions of ZC3H4 and WDR82 subunits with the S5p RNAPII C-terminal domain. ZC3H4 depletion leads to increased divergent antisense transcription, especially at genes that naturally produce divergent antisense transcripts. We further demonstrate that the ZWC complex phosphorylates the previously uncharacterized N-terminal acidic domain of SPT5, a subunit of the transcription-elongation factor DSIF, and that this phosphorylation is responsible for suppressing divergent antisense transcription. Our study provides evidence that the newly identified ZWC-DSIF axis regulates the direction of transcription during the transition from early to productive elongation.
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Affiliation(s)
- Kihyun Park
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, South Korea
| | - Jian Zhong
- Epigenomics Program, Center for Individualized Medicine, Mayo Clinic, Rochester, MN 55905, USA
| | - Jin Sung Jang
- Medical Genome Facility, Center for Individualized Medicine, Mayo Clinic, Rochester, MN 55905, USA
- Division of Experimental Pathology and Laboratory Medicine, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55905, USA
| | - Jihyun Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, South Korea
| | - Hye-Jung Kim
- New Drug Development Center, OSONG Medical Innovation Foundation, Cheongju 28160, South Korea
| | - Jeong-Heon Lee
- Epigenomics Program, Center for Individualized Medicine, Mayo Clinic, Rochester, MN 55905, USA
- Division of Experimental Pathology and Laboratory Medicine, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55905, USA
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905, USA
| | - Jaehoon Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, South Korea
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20
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Liu Z, Wu A, Wu Z, Wang T, Pan Y, Li B, Zhang X, Yu M. TOX4 facilitates promoter-proximal pausing and C-terminal domain dephosphorylation of RNA polymerase II in human cells. Commun Biol 2022; 5:300. [PMID: 35365735 PMCID: PMC8975821 DOI: 10.1038/s42003-022-03214-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Accepted: 03/02/2022] [Indexed: 11/24/2022] Open
Abstract
TOX4 is one of the regulatory factors of PP1 phosphatases with poorly understood functions. Here we show that chromatin occupancy pattern of TOX4 resembles that of RNA polymerase II (Pol II), and its loss increases cellular level of C-terminal domain (CTD) phosphorylated Pol II but mainly decreases Pol II occupancy on promoters. In addition, elongation rate analyses by 4sUDRB-seq suggest that TOX4 restricts pause release and early elongation but promotes late elongation. Moreover, TT-seq analyses indicate that TOX4 loss mainly decreases transcriptional output. Mechanistically, TOX4 may restrict pause release through facilitating CTD serine 2 and DSIF dephosphorylation, and promote Pol II recycling and reinitiation through facilitating CTD serines 2 and 5 dephosphorylation. Furthermore, among the PP1 phosphatases, TOX4 preferentially binds PP1α and is capable of facilitating Pol II CTD dephosphorylation in vitro. These results lay the foundation for a better understanding of the role of TOX4 in transcriptional regulation. As a role of TOX4, one of the regulatory proteins of PP1 phosphatases, in transcriptional regulation, authors here show that TOX4 restricts pause release and early productive elongation, and promotes Pol II recycling and transcriptional reinitiation.
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Affiliation(s)
- Ziling Liu
- Sheng Yushou Center of Cell Biology and Immunology, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 200240, Shanghai, China
| | - Aiwei Wu
- Sheng Yushou Center of Cell Biology and Immunology, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 200240, Shanghai, China
| | - Zhen Wu
- State key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, 200438, Shanghai, China
| | - Talang Wang
- Sheng Yushou Center of Cell Biology and Immunology, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 200240, Shanghai, China
| | - Yixuan Pan
- Department of Biochemistry and Molecular Cell Biology, Shanghai Jiao Tong University School of Medicine, 200025, Shanghai, China
| | - Bing Li
- Department of Biochemistry and Molecular Cell Biology, Shanghai Jiao Tong University School of Medicine, 200025, Shanghai, China
| | - Xumin Zhang
- State key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, 200438, Shanghai, China
| | - Ming Yu
- Sheng Yushou Center of Cell Biology and Immunology, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 200240, Shanghai, China. .,Ministry of Education Key Laboratory of Systems Biomedicine, Shanghai Jiao Tong University, 200240, Shanghai, China.
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21
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Wei Y, Redel C, Ahlner A, Lemak A, Johansson-Åkhe I, Houliston S, Kenney TMG, Tamachi A, Morad V, Duan S, Andrews DW, Wallner B, Sunnerhagen M, Arrowsmith CH, Penn LZ. The MYC oncoprotein directly interacts with its chromatin cofactor PNUTS to recruit PP1 phosphatase. Nucleic Acids Res 2022; 50:3505-3522. [PMID: 35244724 PMCID: PMC8989513 DOI: 10.1093/nar/gkac138] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 01/11/2022] [Accepted: 02/28/2022] [Indexed: 02/07/2023] Open
Abstract
Despite MYC dysregulation in most human cancers, strategies to target this potent oncogenic driver remain an urgent unmet need. Recent evidence shows the PP1 phosphatase and its regulatory subunit PNUTS control MYC phosphorylation, chromatin occupancy, and stability, however the molecular basis remains unclear. Here we demonstrate that MYC interacts directly with PNUTS through the MYC homology Box 0 (MB0), a highly conserved region recently shown to be important for MYC oncogenic activity. By NMR we identified a distinct peptide motif within MB0 that interacts with PNUTS residues 1–148, a functional unit, here termed PNUTS amino-terminal domain (PAD). Using NMR spectroscopy we determined the solution structure of PAD, and characterised its MYC-binding patch. Point mutations of residues at the MYC-PNUTS interface significantly weaken their interaction both in vitro and in vivo, leading to elevated MYC phosphorylation. These data demonstrate that the MB0 region of MYC directly interacts with the PAD of PNUTS, which provides new insight into the control mechanisms of MYC as a regulator of gene transcription and a pervasive cancer driver.
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Affiliation(s)
- Yong Wei
- Princess Margaret Cancer Centre, University Health Network, 101 College St, Toronto, ON M5G 0A3, Canada.,Structural Genomics Consortium (SGC), University of Toronto, 101 College St., Suite 700, Toronto, ON, M5G 1L7, Canada.,Sunnybrook Research Institute, 2075 Bayview Ave. Toronto, ON, M4N 3M5, Canada
| | - Cornelia Redel
- Princess Margaret Cancer Centre, University Health Network, 101 College St, Toronto, ON M5G 0A3, Canada.,Department of Medical Biophysics, University of Toronto, 101 College St, Toronto, ON M5G 1L7, Canada
| | - Alexandra Ahlner
- Department of Physics, Chemistry, and Biology, Linköping University, SE-581 83 Linköping, Sweden
| | - Alexander Lemak
- Princess Margaret Cancer Centre, University Health Network, 101 College St, Toronto, ON M5G 0A3, Canada.,Structural Genomics Consortium (SGC), University of Toronto, 101 College St., Suite 700, Toronto, ON, M5G 1L7, Canada
| | - Isak Johansson-Åkhe
- Department of Physics, Chemistry, and Biology, Linköping University, SE-581 83 Linköping, Sweden
| | - Scott Houliston
- Princess Margaret Cancer Centre, University Health Network, 101 College St, Toronto, ON M5G 0A3, Canada.,Structural Genomics Consortium (SGC), University of Toronto, 101 College St., Suite 700, Toronto, ON, M5G 1L7, Canada
| | - Tristan M G Kenney
- Princess Margaret Cancer Centre, University Health Network, 101 College St, Toronto, ON M5G 0A3, Canada.,Department of Medical Biophysics, University of Toronto, 101 College St, Toronto, ON M5G 1L7, Canada
| | - Aaliya Tamachi
- Princess Margaret Cancer Centre, University Health Network, 101 College St, Toronto, ON M5G 0A3, Canada
| | - Vivian Morad
- Department of Physics, Chemistry, and Biology, Linköping University, SE-581 83 Linköping, Sweden
| | | | - David W Andrews
- Sunnybrook Research Institute, 2075 Bayview Ave. Toronto, ON, M4N 3M5, Canada.,Department of Medical Biophysics, University of Toronto, 101 College St, Toronto, ON M5G 1L7, Canada
| | - Björn Wallner
- Department of Physics, Chemistry, and Biology, Linköping University, SE-581 83 Linköping, Sweden
| | - Maria Sunnerhagen
- Department of Physics, Chemistry, and Biology, Linköping University, SE-581 83 Linköping, Sweden
| | - Cheryl H Arrowsmith
- Princess Margaret Cancer Centre, University Health Network, 101 College St, Toronto, ON M5G 0A3, Canada.,Structural Genomics Consortium (SGC), University of Toronto, 101 College St., Suite 700, Toronto, ON, M5G 1L7, Canada.,Department of Medical Biophysics, University of Toronto, 101 College St, Toronto, ON M5G 1L7, Canada
| | - Linda Z Penn
- Princess Margaret Cancer Centre, University Health Network, 101 College St, Toronto, ON M5G 0A3, Canada.,Department of Medical Biophysics, University of Toronto, 101 College St, Toronto, ON M5G 1L7, Canada
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22
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Kim HS, Jeon Y, Jang YO, Lee H, Shin Y, Lee CW. Mammalian Ssu72 phosphatase preferentially considers tissue-specific actively transcribed gene expression by regulating RNA Pol II transcription. Theranostics 2022; 12:186-206. [PMID: 34987641 PMCID: PMC8690912 DOI: 10.7150/thno.62274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Accepted: 10/26/2021] [Indexed: 11/12/2022] Open
Abstract
Reversible phosphorylation of the C-terminal domain (CTD) of RNA polymerase II (Pol II) is essential for gene expression control. How altering the phosphorylation of the CTD contributes to gene expression in mammalian systems remains poorly understood. Methods: Primary mouse embryonic fibroblasts, hepatocytes, and embryonic stem cells were isolated from conditional Ssu72f/f mice. To knockout the mouse Ssu72 gene, we infected the cells with adenoviruses of incorporated luciferase and Cre recombinase, respectively. RNA sequencing, ChIP sequencing, ChIP assay, immunoblot analyses, qRT-PCR assay, and immunostaining were performed to gain insights into the functional mechanisms of Ssu72 loss in Pol II dynamics. Results: Using primary cells isolated from Ssu72 conditional knockout and transgenic mice, we found that mammalian Ssu72-mediated transcriptional elongation rather than polyadenylation or RNA processing contributed to the transcriptional regulation of various genes. Depletion of Ssu72 resulted in aberrant Pol II pausing and elongation defects. Reduced transcriptional elongation efficiency tended to preferentially affect expression levels of actively transcribed genes in a tissue-specific manner. Furthermore, Ssu72 CTD phosphatase seemed to regulate the phosphorylation levels of CTD Ser2 and Thr4 through accurate modulation of P-TEFb activity and recruitment. Conclusions: Our findings demonstrate that mammalian Ssu72 contributes to the transcription of tissue-specific actively transcribed gene expression by regulating reciprocal phosphorylation of Pol II CTD.
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23
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Hurst V, Challa K, Jonas F, Forey R, Sack R, Seebacher J, Schmid CD, Barkai N, Shimada K, Gasser SM, Poli J. A regulatory phosphorylation site on Mec1 controls chromatin occupancy of RNA polymerases during replication stress. EMBO J 2021; 40:e108439. [PMID: 34569643 PMCID: PMC8561635 DOI: 10.15252/embj.2021108439] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 09/08/2021] [Accepted: 09/10/2021] [Indexed: 01/16/2023] Open
Abstract
Upon replication stress, budding yeast checkpoint kinase Mec1ATR triggers the downregulation of transcription, thereby reducing the level of RNA polymerase (RNAP) on chromatin to facilitate replication fork progression. Here, we identify a hydroxyurea-induced phosphorylation site on Mec1, Mec1-S1991, that contributes to the eviction of RNAPII and RNAPIII during replication stress. The expression of the non-phosphorylatable mec1-S1991A mutant reduces replication fork progression genome-wide and compromises survival on hydroxyurea. This defect can be suppressed by destabilizing chromatin-bound RNAPII through a TAP fusion to its Rpb3 subunit, suggesting that lethality in mec1-S1991A mutants arises from replication-transcription conflicts. Coincident with a failure to repress gene expression on hydroxyurea in mec1-S1991A cells, highly transcribed genes such as GAL1 remain bound at nuclear pores. Consistently, we find that nuclear pore proteins and factors controlling RNAPII and RNAPIII are phosphorylated in a Mec1-dependent manner on hydroxyurea. Moreover, we show that Mec1 kinase also contributes to reduced RNAPII occupancy on chromatin during an unperturbed S phase by promoting degradation of the Rpb1 subunit.
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Affiliation(s)
- Verena Hurst
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.,Faculty of Natural Sciences, University of Basel, Basel, Switzerland
| | - Kiran Challa
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Felix Jonas
- Departments of Molecular Genetics and Physics of Complex Systems, Weizmann Institute of Science, Rehovot, Israel
| | - Romain Forey
- Institut de Génétique Humaine, CNRS, Université de Montpellier, Equipe labélisée Ligue contre le Cancer, Montpellier, France
| | - Ragna Sack
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Jan Seebacher
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Christoph D Schmid
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Naama Barkai
- Departments of Molecular Genetics and Physics of Complex Systems, Weizmann Institute of Science, Rehovot, Israel
| | - Kenji Shimada
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Susan M Gasser
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.,Faculty of Natural Sciences, University of Basel, Basel, Switzerland
| | - Jérôme Poli
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.,Institut de Génétique Humaine, CNRS, Université de Montpellier, Equipe labélisée Ligue contre le Cancer, Montpellier, France
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24
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Kemiha S, Poli J, Lin YL, Lengronne A, Pasero P. Toxic R-loops: Cause or consequence of replication stress? DNA Repair (Amst) 2021; 107:103199. [PMID: 34399314 DOI: 10.1016/j.dnarep.2021.103199] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 07/28/2021] [Accepted: 07/30/2021] [Indexed: 01/08/2023]
Abstract
Transcription-replication conflicts (TRCs) represent a potential source of endogenous replication stress (RS) and genomic instability in eukaryotic cells but the mechanisms that underlie this instability remain poorly understood. Part of the problem could come from non-B DNA structures called R-loops, which are formed of a RNA:DNA hybrid and a displaced ssDNA loop. In this review, we discuss different scenarios in which R-loops directly or indirectly interfere with DNA replication. We also present other types of TRCs that may not depend on R-loops to impede fork progression. Finally, we discuss alternative models in which toxic RNA:DNA hybrids form at stalled forks as a consequence - but not a cause - of replication stress and interfere with replication resumption.
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Affiliation(s)
- Samira Kemiha
- Institut de Génétique Humaine, CNRS et Université de Montpellier, Equipe labélisée Ligue contre le Cancer, Montpellier, France
| | - Jérôme Poli
- Institut de Génétique Humaine, CNRS et Université de Montpellier, Equipe labélisée Ligue contre le Cancer, Montpellier, France
| | - Yea-Lih Lin
- Institut de Génétique Humaine, CNRS et Université de Montpellier, Equipe labélisée Ligue contre le Cancer, Montpellier, France
| | - Armelle Lengronne
- Institut de Génétique Humaine, CNRS et Université de Montpellier, Equipe labélisée Ligue contre le Cancer, Montpellier, France
| | - Philippe Pasero
- Institut de Génétique Humaine, CNRS et Université de Montpellier, Equipe labélisée Ligue contre le Cancer, Montpellier, France.
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Rødland GE, Hauge S, Hasvold G, Bay LTE, Raabe TTH, Joel M, Syljuåsen RG. Differential Effects of Combined ATR/WEE1 Inhibition in Cancer Cells. Cancers (Basel) 2021; 13:cancers13153790. [PMID: 34359691 PMCID: PMC8345075 DOI: 10.3390/cancers13153790] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2021] [Accepted: 07/13/2021] [Indexed: 01/14/2023] Open
Abstract
Simple Summary Cancer cells often show elevated replication stress and loss of cell cycle checkpoints. The ataxia telangiectasia and Rad3-related (ATR) and WEE1 kinases play roles in protecting cancer cells from high replication stress and in regulating the remaining cell cycle checkpoints. Inhibitors of ATR or WEE1 therefore have the potential to selectively kill cancer cells and are currently being tested in clinical trials. However, more studies are needed to understand how these inhibitors work in various types of cancer and to find the most effective ways of using them. Here, we have explored whether simultaneous treatment with ATR and WEE1 inhibitors is a promising approach. Effects were investigated in cell lines from osteosarcoma and lung cancer. We expect our results to be of importance for future treatment strategies with these inhibitors. Abstract Inhibitors of WEE1 and ATR kinases are considered promising for cancer treatment, either as monotherapy or in combination with chemo- or radiotherapy. Here, we addressed whether simultaneous inhibition of WEE1 and ATR might be advantageous. Effects of the WEE1 inhibitor MK1775 and ATR inhibitor VE822 were investigated in U2OS osteosarcoma cells and in four lung cancer cell lines, H460, A549, H1975, and SW900, with different sensitivities to the WEE1 inhibitor. Despite the differences in cytotoxic effects, the WEE1 inhibitor reduced the inhibitory phosphorylation of CDK, leading to increased CDK activity accompanied by ATR activation in all cell lines. However, combining ATR inhibition with WEE1 inhibition could not fully compensate for cell resistance to the WEE1 inhibitor and reduced cell viability to a variable extent. The decreased cell viability upon the combined treatment correlated with a synergistic induction of DNA damage in S-phase in U2OS cells but not in the lung cancer cells. Moreover, less synergy was found between ATR and WEE1 inhibitors upon co-treatment with radiation, suggesting that single inhibitors may be preferable together with radiotherapy. Altogether, our results support that combining WEE1 and ATR inhibitors may be beneficial for cancer treatment in some cases, but also highlight that the effects vary between cancer cell lines.
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Lalonde M, Trauner M, Werner M, Hamperl S. Consequences and Resolution of Transcription-Replication Conflicts. Life (Basel) 2021; 11:life11070637. [PMID: 34209204 PMCID: PMC8303131 DOI: 10.3390/life11070637] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2021] [Revised: 06/28/2021] [Accepted: 06/28/2021] [Indexed: 11/17/2022] Open
Abstract
Transcription–replication conflicts occur when the two critical cellular machineries responsible for gene expression and genome duplication collide with each other on the same genomic location. Although both prokaryotic and eukaryotic cells have evolved multiple mechanisms to coordinate these processes on individual chromosomes, it is now clear that conflicts can arise due to aberrant transcription regulation and premature proliferation, leading to DNA replication stress and genomic instability. As both are considered hallmarks of aging and human diseases such as cancer, understanding the cellular consequences of conflicts is of paramount importance. In this article, we summarize our current knowledge on where and when collisions occur and how these encounters affect the genome and chromatin landscape of cells. Finally, we conclude with the different cellular pathways and multiple mechanisms that cells have put in place at conflict sites to ensure the resolution of conflicts and accurate genome duplication.
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Cossa G, Parua PK, Eilers M, Fisher RP. Protein phosphatases in the RNAPII transcription cycle: erasers, sculptors, gatekeepers, and potential drug targets. Genes Dev 2021; 35:658-676. [PMID: 33888562 PMCID: PMC8091971 DOI: 10.1101/gad.348315.121] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
In this review, Cossa et al. discuss the current knowledge and outstanding questions about phosphatases in the context of the RNAPII transcription cycle. The transcription cycle of RNA polymerase II (RNAPII) is governed at multiple points by opposing actions of cyclin-dependent kinases (CDKs) and protein phosphatases, in a process with similarities to the cell division cycle. While important roles of the kinases have been established, phosphatases have emerged more slowly as key players in transcription, and large gaps remain in understanding of their precise functions and targets. Much of the earlier work focused on the roles and regulation of sui generis and often atypical phosphatases—FCP1, Rtr1/RPAP2, and SSU72—with seemingly dedicated functions in RNAPII transcription. Decisive roles in the transcription cycle have now been uncovered for members of the major phosphoprotein phosphatase (PPP) family, including PP1, PP2A, and PP4—abundant enzymes with pleiotropic roles in cellular signaling pathways. These phosphatases appear to act principally at the transitions between transcription cycle phases, ensuring fine control of elongation and termination. Much is still unknown, however, about the division of labor among the PPP family members, and their possible regulation by or of the transcriptional kinases. CDKs active in transcription have recently drawn attention as potential therapeutic targets in cancer and other diseases, raising the prospect that the phosphatases might also present opportunities for new drug development. Here we review the current knowledge and outstanding questions about phosphatases in the context of the RNAPII transcription cycle.
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Affiliation(s)
- Giacomo Cossa
- Department of Biochemistry and Molecular Biology, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Pabitra K Parua
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Martin Eilers
- Department of Biochemistry and Molecular Biology, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Robert P Fisher
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
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28
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Hauge S, Eek Mariampillai A, Rødland GE, Bay LTE, Landsverk HB, Syljuåsen RG. Expanding roles of cell cycle checkpoint inhibitors in radiation oncology. Int J Radiat Biol 2021; 99:941-950. [PMID: 33877959 DOI: 10.1080/09553002.2021.1913529] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
PURPOSE Radiation-induced activation of cell cycle checkpoints have been of long-standing interest. The WEE1, CHK1 and ATR kinases are key factors in cell cycle checkpoint regulation and are essential for the S and G2 checkpoints. Here, we review the rationale for why inhibitors of WEE1, CHK1 and ATR could be beneficial in combination with radiation. CONCLUSIONS Combined treatment with radiation and inhibitors of these kinases results in checkpoint abrogation and subsequent mitotic catastrophe. This might selectively radiosensitize tumor cells, as they often lack the p53-dependent G1 checkpoint and therefore rely more on the G2 checkpoint to repair DNA damage. Further affecting the repair of radiation damage, inhibition of WEE1, CHK1 or ATR also specifically suppresses the homologous recombination repair pathway. Moreover, inhibition of these kinases can induce massive replication stress during S phase of the cell cycle, likely contributing to eliminate radioresistant S phase cells. Intriguingly, recent findings suggest that cell cycle checkpoint inhibitors in combination with radiation can also enhance anti-tumor immune effects. Altogether, the expanding knowledge about the functional roles of WEE1, CHK1 and ATR inhibitors support that they are promising candidates for use in combination with radiation treatment.
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Affiliation(s)
- Sissel Hauge
- Department of Radiation Biology, Institute for Cancer Research, Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway
| | - Adrian Eek Mariampillai
- Department of Radiation Biology, Institute for Cancer Research, Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway
| | - Gro Elise Rødland
- Department of Radiation Biology, Institute for Cancer Research, Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway
| | - Lilli T E Bay
- Department of Radiation Biology, Institute for Cancer Research, Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway
| | - Helga B Landsverk
- Department of Radiation Biology, Institute for Cancer Research, Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway
| | - Randi G Syljuåsen
- Department of Radiation Biology, Institute for Cancer Research, Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway
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29
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Landsverk HB, Sandquist LE, Bay LTE, Syljuåsen RG. New link between the RNA polymerase II-CTD and replication stress. Mol Cell Oncol 2021; 8:1910008. [PMID: 34027044 PMCID: PMC8128203 DOI: 10.1080/23723556.2021.1910008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Conflicts between transcription and replication are a major source of replication stress. Our recent findings show that proper dephosphorylation of Serine 5 in the carboxy-terminal domain (CTD) of DNA-directed RNA polymerase II subunit RPB1 is needed to prevent such conflicts in human cells.
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Affiliation(s)
- Helga B Landsverk
- Department of Radiation Biology, Institute for Cancer Research, Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway
| | - Lise E Sandquist
- Department of Radiation Biology, Institute for Cancer Research, Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway
| | - Lilli T E Bay
- Department of Radiation Biology, Institute for Cancer Research, Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway
| | - Randi G Syljuåsen
- Department of Radiation Biology, Institute for Cancer Research, Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway
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