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Tsao N, Ashour ME, Mosammaparast N. How RNA impacts DNA repair. DNA Repair (Amst) 2023; 131:103564. [PMID: 37776841 PMCID: PMC11232704 DOI: 10.1016/j.dnarep.2023.103564] [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: 05/16/2023] [Revised: 08/22/2023] [Accepted: 08/23/2023] [Indexed: 10/02/2023]
Abstract
The central dogma of molecular biology posits that genetic information flows unidirectionally, from DNA, to RNA, and finally to protein. However, this directionality is broken in some cases, such as reverse transcription where RNA is converted to DNA by retroviruses and certain transposable elements. Our genomes have evolved and adapted to the presence of reverse transcription. Similarly, our genome is continuously maintained by several repair pathways to reverse damage due to various endogenous and exogenous sources. More recently, evidence has revealed that RNA, while in certain contexts may be detrimental for genome stability, is involved in promoting certain types of DNA repair. Depending on the pathway in question, the size of these DNA repair-associated RNAs range from one or a few ribonucleotides to long fragments of RNA. Moreover, RNA is highly modified, and RNA modifications have been revealed to be functionally associated with specific DNA repair pathways. In this review, we highlight aspects of this unexpected layer of genomic maintenance, demonstrating how RNA may influence DNA integrity.
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Affiliation(s)
- Ning Tsao
- Department of Pathology & Immunology, Division of Laboratory and Genomic Medicine, Center for Genome Integrity, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Mohamed E Ashour
- Department of Pathology & Immunology, Division of Laboratory and Genomic Medicine, Center for Genome Integrity, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Nima Mosammaparast
- Department of Pathology & Immunology, Division of Laboratory and Genomic Medicine, Center for Genome Integrity, Washington University School of Medicine, St. Louis, MO 63110, USA.
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2
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Post-Transcriptional and Post-Translational Modifications in Telomerase Biogenesis and Recruitment to Telomeres. Int J Mol Sci 2023; 24:ijms24055027. [PMID: 36902458 PMCID: PMC10003056 DOI: 10.3390/ijms24055027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 03/02/2023] [Accepted: 03/03/2023] [Indexed: 03/08/2023] Open
Abstract
Telomere length is associated with the proliferative potential of cells. Telomerase is an enzyme that elongates telomeres throughout the entire lifespan of an organism in stem cells, germ cells, and cells of constantly renewed tissues. It is activated during cellular division, including regeneration and immune responses. The biogenesis of telomerase components and their assembly and functional localization to the telomere is a complex system regulated at multiple levels, where each step must be tuned to the cellular requirements. Any defect in the function or localization of the components of the telomerase biogenesis and functional system will affect the maintenance of telomere length, which is critical to the processes of regeneration, immune response, embryonic development, and cancer progression. An understanding of the regulatory mechanisms of telomerase biogenesis and activity is necessary for the development of approaches toward manipulating telomerase to influence these processes. The present review focuses on the molecular mechanisms involved in the major steps of telomerase regulation and the role of post-transcriptional and post-translational modifications in telomerase biogenesis and function in yeast and vertebrates.
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3
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CCAR2 functions downstream of the Shieldin complex to promote double-strand break end-joining. Proc Natl Acad Sci U S A 2022; 119:e2214935119. [PMID: 36442094 PMCID: PMC9894118 DOI: 10.1073/pnas.2214935119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The 53BP1-RIF1 pathway restricts the resection of DNA double-strand breaks (DSBs) and promotes blunt end-ligation by non-homologous end joining (NHEJ) repair. The Shieldin complex is a downstream effector of the 53BP1-RIF1 pathway. Here, we identify a component of this pathway, CCAR2/DBC1, which is also required for restriction of DNA end-resection. CCAR2 co-immunoprecipitates with the Shieldin complex, and knockout of CCAR2 in a BRCA1-deficient cell line results in elevated DSB end-resection, RAD51 loading, and PARP inhibitor (PARPi) resistance. Knockout of CCAR2 is epistatic with knockout of other Shieldin proteins. The S1-like RNA-binding domain of CCAR2 is required for its interaction with the Shieldin complex and for suppression of DSB end-resection. CCAR2 functions downstream of the Shieldin complex, and CCAR2 knockout cells have delayed resolution of Shieldin complex foci. Forkhead-associated (FHA)-dependent targeting of CCAR2 to DSB sites re-sensitized BRCA1-/-SHLD2-/- cells to PARPi. Taken together, CCAR2 is a functional component of the 53BP1-RIF1 pathway, promotes the refill of resected DSBs, and suppresses homologous recombination.
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4
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Bordelet H, Costa R, Brocas C, Dépagne J, Veaute X, Busso D, Batté A, Guérois R, Marcand S, Dubrana K. Sir3 heterochromatin protein promotes non-homologous end joining by direct inhibition of Sae2. EMBO J 2022; 41:e108813. [PMID: 34817085 PMCID: PMC8724767 DOI: 10.15252/embj.2021108813] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 11/02/2021] [Accepted: 11/04/2021] [Indexed: 01/07/2023] Open
Abstract
Heterochromatin is a conserved feature of eukaryotic chromosomes, with central roles in gene expression regulation and maintenance of genome stability. How heterochromatin proteins regulate DNA repair remains poorly described. In the yeast Saccharomyces cerevisiae, the silent information regulator (SIR) complex assembles heterochromatin-like chromatin at sub-telomeric chromosomal regions. SIR-mediated repressive chromatin limits DNA double-strand break (DSB) resection, thus protecting damaged chromosome ends during homologous recombination (HR). As resection initiation represents the crossroads between repair by non-homologous end joining (NHEJ) or HR, we asked whether SIR-mediated heterochromatin regulates NHEJ. We show that SIRs promote NHEJ through two pathways, one depending on repressive chromatin assembly, and the other relying on Sir3 in a manner that is independent of its heterochromatin-promoting function. Via physical interaction with the Sae2 protein, Sir3 impairs Sae2-dependent functions of the MRX (Mre11-Rad50-Xrs2) complex, thereby limiting Mre11-mediated resection, delaying MRX removal from DSB ends, and promoting NHEJ.
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Affiliation(s)
- Hélène Bordelet
- Université de Paris and Université Paris‐Saclay, INSERM, iRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et RadiationsFontenay‐aux‐RosesFrance
- Régulation spatiale des génomes, Institut Pasteur, CNRS UMR3525ParisFrance
| | - Rafaël Costa
- Université de Paris and Université Paris‐Saclay, INSERM, iRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et RadiationsFontenay‐aux‐RosesFrance
| | - Clémentine Brocas
- Université de Paris and Université Paris‐Saclay, INSERM, iRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et RadiationsFontenay‐aux‐RosesFrance
| | - Jordane Dépagne
- CIGEx platform. Université de Paris and Université Paris‐Saclay, INSERM, iRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et RadiationsFontenay‐aux‐RosesFrance
| | - Xavier Veaute
- CIGEx platform. Université de Paris and Université Paris‐Saclay, INSERM, iRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et RadiationsFontenay‐aux‐RosesFrance
| | - Didier Busso
- CIGEx platform. Université de Paris and Université Paris‐Saclay, INSERM, iRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et RadiationsFontenay‐aux‐RosesFrance
| | - Amandine Batté
- Université de Paris and Université Paris‐Saclay, INSERM, iRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et RadiationsFontenay‐aux‐RosesFrance
- Center for Integrative GenomicsBâtiment GénopodeUniversity of LausanneLausanneSwitzerland
| | - Raphaël Guérois
- Institute for Integrative Biology of the Cell (I2BC)CEA, CNRS, Université Paris‐Sud, Université Paris‐SaclayGif‐sur‐YvetteFrance
| | - Stéphane Marcand
- Université de Paris and Université Paris‐Saclay, INSERM, iRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et RadiationsFontenay‐aux‐RosesFrance
| | - Karine Dubrana
- Université de Paris and Université Paris‐Saclay, INSERM, iRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et RadiationsFontenay‐aux‐RosesFrance
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5
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Unfried JP, Marín-Baquero M, Rivera-Calzada Á, Razquin N, Martín-Cuevas EM, de Bragança S, Aicart-Ramos C, McCoy C, Prats-Mari L, Arribas-Bosacoma R, Lee L, Caruso S, Zucman-Rossi J, Sangro B, Williams G, Moreno-Herrero F, Llorca O, Lees-Miller SP, Fortes P. Long Noncoding RNA NIHCOLE Promotes Ligation Efficiency of DNA Double-Strand Breaks in Hepatocellular Carcinoma. Cancer Res 2021; 81:4910-4925. [PMID: 34321241 PMCID: PMC8488005 DOI: 10.1158/0008-5472.can-21-0463] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 06/25/2021] [Accepted: 07/26/2021] [Indexed: 11/16/2022]
Abstract
Long noncoding RNAs (lncRNA) are emerging as key players in cancer as parts of poorly understood molecular mechanisms. Here, we investigated lncRNAs that play a role in hepatocellular carcinoma (HCC) and identified NIHCOLE, a novel lncRNA induced in HCC with oncogenic potential and a role in the ligation efficiency of DNA double-stranded breaks (DSB). NIHCOLE expression was associated with poor prognosis and survival of HCC patients. Depletion of NIHCOLE from HCC cells led to impaired proliferation and increased apoptosis. NIHCOLE deficiency led to accumulation of DNA damage due to a specific decrease in the activity of the nonhomologous end-joining (NHEJ) pathway of DSB repair. DNA damage induction in NIHCOLE-depleted cells further decreased HCC cell growth. NIHCOLE was associated with DSB markers and recruited several molecules of the Ku70/Ku80 heterodimer. Further, NIHCOLE putative structural domains supported stable multimeric complexes formed by several NHEJ factors including Ku70/80, APLF, XRCC4, and DNA ligase IV. NHEJ reconstitution assays showed that NIHCOLE promoted the ligation efficiency of blunt-ended DSBs. Collectively, these data show that NIHCOLE serves as a scaffold and facilitator of NHEJ machinery and confers an advantage to HCC cells, which could be exploited as a targetable vulnerability. SIGNIFICANCE: This study characterizes the role of lncRNA NIHCOLE in DNA repair and cellular fitness in HCC, thus implicating it as a therapeutic target.See related commentary by Barcena-Varela and Lujambio, p. 4899.
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MESH Headings
- Biomarkers, Tumor
- Carcinoma, Hepatocellular/diagnosis
- Carcinoma, Hepatocellular/genetics
- Carcinoma, Hepatocellular/mortality
- Cell Line, Tumor
- DNA Breaks, Double-Stranded
- DNA End-Joining Repair
- Gene Expression Profiling
- Gene Expression Regulation, Neoplastic
- High-Throughput Nucleotide Sequencing
- Humans
- Liver Neoplasms/diagnosis
- Liver Neoplasms/genetics
- Liver Neoplasms/mortality
- Models, Biological
- Nucleic Acid Conformation
- Nucleotide Motifs
- Prognosis
- RNA, Long Noncoding/chemistry
- RNA, Long Noncoding/genetics
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Affiliation(s)
- Juan P Unfried
- Department of Gene Therapy and Regulation of Gene Expression, Center for Applied Medical Research (CIMA), University of Navarra (UNAV), Pamplona, Spain.
| | - Mikel Marín-Baquero
- Department of Macromolecular Structures, Spanish National Centre for Biotechnology (CNB), Spanish National Research Council (CSIC), Madrid, Spain
| | - Ángel Rivera-Calzada
- Structural Biology Program, Spanish National Cancer Research Center (CNIO), Madrid, Spain
| | - Nerea Razquin
- Department of Gene Therapy and Regulation of Gene Expression, Center for Applied Medical Research (CIMA), University of Navarra (UNAV), Pamplona, Spain
| | - Eva M Martín-Cuevas
- Department of Macromolecular Structures, Spanish National Centre for Biotechnology (CNB), Spanish National Research Council (CSIC), Madrid, Spain
| | - Sara de Bragança
- Department of Macromolecular Structures, Spanish National Centre for Biotechnology (CNB), Spanish National Research Council (CSIC), Madrid, Spain
| | - Clara Aicart-Ramos
- Department of Macromolecular Structures, Spanish National Centre for Biotechnology (CNB), Spanish National Research Council (CSIC), Madrid, Spain
| | - Christopher McCoy
- Department of Biochemistry and Molecular Biology, Robson DNA Science Centre, Arnie Charbonneau Cancer Institute, Cumming School of Medicine, University of Calgary, Calgary, Canada
| | - Laura Prats-Mari
- Department of Gene Therapy and Regulation of Gene Expression, Center for Applied Medical Research (CIMA), University of Navarra (UNAV), Pamplona, Spain
| | - Raquel Arribas-Bosacoma
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, UK
| | - Linda Lee
- Department of Biochemistry and Molecular Biology, Robson DNA Science Centre, Arnie Charbonneau Cancer Institute, Cumming School of Medicine, University of Calgary, Calgary, Canada
| | - Stefano Caruso
- Centre de Recherche des Cordeliers, Sorbonne Université, Université de Paris, INSERM, Functional Genomics of Solid Tumors laboratory, Équipe Labellisée Ligue Nationale Contre le Cancer, Labex OncoImmunology, Paris, France
| | - Jessica Zucman-Rossi
- Centre de Recherche des Cordeliers, Sorbonne Université, Université de Paris, INSERM, Functional Genomics of Solid Tumors laboratory, Équipe Labellisée Ligue Nationale Contre le Cancer, Labex OncoImmunology, Paris, France
| | - Bruno Sangro
- University of Navarra Clinic (CUN), Liver Unit, Pamplona, Spain
- Navarra Institute for Health Research (IdiSNA), Pamplona, Spain
- Liver and Digestive Diseases Networking Biomedical Research Centre (CIBERehd), Madrid, Spain
| | - Gareth Williams
- Department of Biochemistry and Molecular Biology, Robson DNA Science Centre, Arnie Charbonneau Cancer Institute, Cumming School of Medicine, University of Calgary, Calgary, Canada
| | - Fernando Moreno-Herrero
- Department of Macromolecular Structures, Spanish National Centre for Biotechnology (CNB), Spanish National Research Council (CSIC), Madrid, Spain
| | - Oscar Llorca
- Structural Biology Program, Spanish National Cancer Research Center (CNIO), Madrid, Spain
| | - Susan P Lees-Miller
- Department of Biochemistry and Molecular Biology, Robson DNA Science Centre, Arnie Charbonneau Cancer Institute, Cumming School of Medicine, University of Calgary, Calgary, Canada
| | - Puri Fortes
- Department of Gene Therapy and Regulation of Gene Expression, Center for Applied Medical Research (CIMA), University of Navarra (UNAV), Pamplona, Spain.
- Navarra Institute for Health Research (IdiSNA), Pamplona, Spain
- Liver and Digestive Diseases Networking Biomedical Research Centre (CIBERehd), Madrid, Spain
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6
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Audoynaud C, Vagner S, Lambert S. Non-homologous end-joining at challenged replication forks: an RNA connection? Trends Genet 2021; 37:973-985. [PMID: 34238592 DOI: 10.1016/j.tig.2021.06.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 05/20/2021] [Accepted: 06/11/2021] [Indexed: 12/29/2022]
Abstract
Defective DNA replication, known as 'replication stress', is a source of DNA damage, a hallmark of numerous human diseases, including cancer, developmental defect, neurological disorders, and premature aging. Recent work indicates that non-homologous end-joining (NHEJ) is unexpectedly active during DNA replication to repair replication-born DNA lesions and to safeguard replication fork integrity. However, erroneous NHEJ events are deleterious to genome stability. RNAs are novel regulators of NHEJ activity through their ability to modulate the assembly of repair complexes in trans. At DNA damage sites, RNAs and DNA-embedded ribonucleotides modulate repair efficiency and fidelity. We discuss here how RNAs and associated proteins, including RNA binding proteins, may regulate NHEJ to sustain genome stability during DNA replication.
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Affiliation(s)
- Charlotte Audoynaud
- Institut Curie, Université PSL, CNRS UMR3348, INSERM U1278, 91400 Orsay, France; Université Paris-Saclay, CNRS UMR3348, INSERM U1278, 91400 Orsay, France; Equipes Labélisées Ligue Nationale Contre Le Cancer, 91400 Orsay, France
| | - Stéphan Vagner
- Institut Curie, Université PSL, CNRS UMR3348, INSERM U1278, 91400 Orsay, France; Université Paris-Saclay, CNRS UMR3348, INSERM U1278, 91400 Orsay, France; Equipes Labélisées Ligue Nationale Contre Le Cancer, 91400 Orsay, France
| | - Sarah Lambert
- Institut Curie, Université PSL, CNRS UMR3348, INSERM U1278, 91400 Orsay, France; Université Paris-Saclay, CNRS UMR3348, INSERM U1278, 91400 Orsay, France; Equipes Labélisées Ligue Nationale Contre Le Cancer, 91400 Orsay, France.
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7
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Fijen C, Rothenberg E. The evolving complexity of DNA damage foci: RNA, condensates and chromatin in DNA double-strand break repair. DNA Repair (Amst) 2021; 105:103170. [PMID: 34256335 DOI: 10.1016/j.dnarep.2021.103170] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 06/08/2021] [Accepted: 06/28/2021] [Indexed: 02/06/2023]
Abstract
Formation of biomolecular condensates is increasingly recognized as a mechanism employed by cells to deal with stress and to optimize enzymatic reactions. Recent studies have characterized several DNA repair foci as phase-separated condensates, behaving like liquid droplets. Concomitantly, the apparent importance of long non-coding RNAs and RNA-binding proteins for the repair of double-strand breaks has raised many questions about their exact contribution to the repair process. Here we discuss how RNA molecules can participate in condensate formation and how RNA-binding proteins can act as molecular scaffolds. We furthermore summarize our current knowledge about how properties of condensates can influence the choice of repair pathway (homologous recombination or non-homologous end joining) and identify the open questions in this field of emerging importance.
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Affiliation(s)
- Carel Fijen
- Department of Biochemistry and Molecular Pharmacology, NYU Grossman School of Medicine, New York, USA.
| | - Eli Rothenberg
- Department of Biochemistry and Molecular Pharmacology, NYU Grossman School of Medicine, New York, USA.
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8
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Hu X, Kim JK, Yu C, Jun HI, Liu J, Sankaran B, Huang L, Qiao F. Quality-Control Mechanism for Telomerase RNA Folding in the Cell. Cell Rep 2020; 33:108568. [PMID: 33378677 DOI: 10.1016/j.celrep.2020.108568] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Revised: 11/12/2020] [Accepted: 12/07/2020] [Indexed: 01/28/2023] Open
Abstract
Long non-coding RNAs can often fold into different conformations. Telomerase RNA, an essential component of the telomerase ribonucleoprotein (RNP) enzyme, must fold into a defined structure to fulfill its function with the protein catalytic subunit (TERT) and other accessory factors. However, the mechanism by which the correct folding of telomerase RNA is warranted in a cell is still unknown. Here we show that La-related protein Pof8 specifically recognizes the conserved pseudoknot region of telomerase RNA and instructs the binding of the Lsm2-8 complex to its mature 3' end, thus selectively protecting the correctly folded RNA from exonucleolytic degradation. In the absence of Pof8, TERT assembles with misfolded RNA and produces little telomerase activity. Therefore, Pof8 plays a key role in telomerase RNA folding quality control, ensuring that TERT only assembles with functional telomerase RNA to form active telomerase. Our finding reveals a mechanism for non-coding RNA folding quality control.
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Affiliation(s)
- Xichan Hu
- Department of Biological Chemistry, School of Medicine, University of California, Irvine, CA 92697-1700, USA
| | - Jin-Kwang Kim
- Department of Biological Chemistry, School of Medicine, University of California, Irvine, CA 92697-1700, USA
| | - Clinton Yu
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA 92697-4560, USA
| | - Hyun-Ik Jun
- Department of Biological Chemistry, School of Medicine, University of California, Irvine, CA 92697-1700, USA
| | - Jinqiang Liu
- Department of Biological Chemistry, School of Medicine, University of California, Irvine, CA 92697-1700, USA
| | - Banumathi Sankaran
- Molecular Biophysics and Integrated Bioimaging, Berkeley Center for Structural Biology, Lawrence Berkeley Laboratory, Berkeley, CA 94720, USA
| | - Lan Huang
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA 92697-4560, USA
| | - Feng Qiao
- Department of Biological Chemistry, School of Medicine, University of California, Irvine, CA 92697-1700, USA.
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9
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Thapar R, Wang JL, Hammel M, Ye R, Liang K, Sun C, Hnizda A, Liang S, Maw SS, Lee L, Villarreal H, Forrester I, Fang S, Tsai MS, Blundell TL, Davis AJ, Lin C, Lees-Miller SP, Strick TR, Tainer J. Mechanism of efficient double-strand break repair by a long non-coding RNA. Nucleic Acids Res 2020; 48:10953-10972. [PMID: 33045735 PMCID: PMC7641761 DOI: 10.1093/nar/gkaa784] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 08/26/2020] [Accepted: 09/09/2020] [Indexed: 12/28/2022] Open
Abstract
Mechanistic studies in DNA repair have focused on roles of multi-protein DNA complexes, so how long non-coding RNAs (lncRNAs) regulate DNA repair is less well understood. Yet, lncRNA LINP1 is over-expressed in multiple cancers and confers resistance to ionizing radiation and chemotherapeutic drugs. Here, we unveil structural and mechanistic insights into LINP1's ability to facilitate non-homologous end joining (NHEJ). We characterized LINP1 structure and flexibility and analyzed interactions with the NHEJ factor Ku70/Ku80 (Ku) and Ku complexes that direct NHEJ. LINP1 self-assembles into phase-separated condensates via RNA-RNA interactions that reorganize to form filamentous Ku-containing aggregates. Structured motifs in LINP1 bind Ku, promoting Ku multimerization and stabilization of the initial synaptic event for NHEJ. Significantly, LINP1 acts as an effective proxy for PAXX. Collective results reveal how lncRNA effectively replaces a DNA repair protein for efficient NHEJ with implications for development of resistance to cancer therapy.
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Affiliation(s)
- Roopa Thapar
- Department of Molecular and Cellular Oncology, University of Texas M.D. Anderson Cancer Center, Houston, TX 77030, USA
| | - Jing L Wang
- Ecole Normale Supérieure, IBENS, CNRS, INSERM, PSL Research University, Paris 75005, France
| | - Michal Hammel
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, 1 Cyclotron Rd, Berkeley, CA 94720, USA
| | - Ruiqiong Ye
- Department of Biochemistry and Molecular Biology, Robson DNA Science Centre, Charbonneau Cancer Institute, University of Calgary, Alberta, T2N 4N1, Canada
| | - Ke Liang
- Department of Molecular and Cellular Oncology, University of Texas M.D. Anderson Cancer Center, Houston, TX 77030, USA
| | - Chengcao Sun
- Department of Molecular and Cellular Oncology, University of Texas M.D. Anderson Cancer Center, Houston, TX 77030, USA
| | - Ales Hnizda
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, UK
| | - Shikang Liang
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, UK
| | - Su S Maw
- Biological Systems and Bioengineering, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Linda Lee
- Department of Biochemistry and Molecular Biology, Robson DNA Science Centre, Charbonneau Cancer Institute, University of Calgary, Alberta, T2N 4N1, Canada
| | | | - Isaac Forrester
- CryoEM Core at Baylor College of Medicine, Houston, Texas 77030, USA
| | - Shujuan Fang
- Department of Biochemistry and Molecular Biology, Robson DNA Science Centre, Charbonneau Cancer Institute, University of Calgary, Alberta, T2N 4N1, Canada
| | - Miaw-Sheue Tsai
- Biological Systems and Bioengineering, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Tom L Blundell
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, UK
| | - Anthony J Davis
- Division of Molecular Radiation Biology, Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Chunru Lin
- Department of Molecular and Cellular Oncology, University of Texas M.D. Anderson Cancer Center, Houston, TX 77030, USA
| | - Susan P Lees-Miller
- Department of Biochemistry and Molecular Biology, Robson DNA Science Centre, Charbonneau Cancer Institute, University of Calgary, Alberta, T2N 4N1, Canada
| | - Terence R Strick
- Ecole Normale Supérieure, IBENS, CNRS, INSERM, PSL Research University, Paris 75005, France
- Programme “Equipe Labellisée’’, Ligue Nationale Contre le Cancer, Paris 75005, France
| | - John A Tainer
- Department of Molecular and Cellular Oncology, University of Texas M.D. Anderson Cancer Center, Houston, TX 77030, USA
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, 1 Cyclotron Rd, Berkeley, CA 94720, USA
- Department of Cancer Biology, University of Texas M.D. Anderson Cancer Center, Houston, TX 77030, USA
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10
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LRIK interacts with the Ku70-Ku80 heterodimer enhancing the efficiency of NHEJ repair. Cell Death Differ 2020; 27:3337-3353. [PMID: 32587379 DOI: 10.1038/s41418-020-0581-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 06/10/2020] [Accepted: 06/12/2020] [Indexed: 12/15/2022] Open
Abstract
Despite recent advances in our understanding of the function of long noncoding RNAs (lncRNAs), their roles and functions in DNA repair pathways remain poorly understood. By screening a panel of uncharacterized lncRNAs to identify those whose transcription is induced by double-strand breaks (DSBs), we identified a novel lncRNA referred to as LRIK that interacts with Ku, which enhances the ability of the Ku heterodimer to detect the presence of DSBs. Here, we show that depletion of LRIK generates significantly enhanced sensitivity to DSB-inducing agents and reduced DSB repair efficiency. In response to DSBs, LRIK enhances the recruitment of repair factors at DSB sites and facilitates γH2AX signaling. Our results demonstrate that LRIK is necessary for efficient repairing DSBs via nonhomologous end-joining pathway.
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11
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Zappulla DC. Yeast Telomerase RNA Flexibly Scaffolds Protein Subunits: Results and Repercussions. Molecules 2020; 25:E2750. [PMID: 32545864 PMCID: PMC7356895 DOI: 10.3390/molecules25122750] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 06/09/2020] [Accepted: 06/11/2020] [Indexed: 12/25/2022] Open
Abstract
It is said that "hindsight is 20-20", so, given the current year, it is an opportune time to review and learn from experiences studying long noncoding RNAs. Investigation of the Saccharomyces cerevisiae telomerase RNA, TLC1, has unveiled striking flexibility in terms of both structural and functional features. Results support the "flexible scaffold" hypothesis for this 1157-nt telomerase RNA. This model describes TLC1 acting as a tether for holoenzyme protein subunits, and it also may apply to a plethora of RNAs beyond telomerase, such as types of lncRNAs. In this short perspective review, I summarize findings from studying the large yeast telomerase ribonucleoprotein (RNP) complex in the hope that this hindsight will sharpen foresight as so many of us seek to mechanistically understand noncoding RNA molecules from vast transcriptomes.
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Affiliation(s)
- David C Zappulla
- Department of Biological Sciences, Lehigh University, Bethlehem, PA 18015, USA
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12
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Shadrina O, Garanina I, Korolev S, Zatsepin T, Van Assche J, Daouad F, Wallet C, Rohr O, Gottikh M. Analysis of RNA binding properties of human Ku protein reveals its interactions with 7SK snRNA and protein components of 7SK snRNP complex. Biochimie 2020; 171-172:110-123. [PMID: 32105815 DOI: 10.1016/j.biochi.2020.02.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 02/21/2020] [Indexed: 12/21/2022]
Abstract
Human Ku heterodimeric protein composed of Ku70 and Ku80 subunits plays an important role in the non-homologous end-joining DNA repair pathway as a sensor of double strand DNA breaks. Ku is also involved in numerous cellular processes, and in some of them it acts in an RNA-dependent manner. However, RNA binding properties of the human Ku have not been well studied. Here we have analyzed interactions of a recombinant Ku heterodimer with a set of RNAs of various structure as well as eCLIP (enhanced crosslinking and immunoprecipitation) data for human Ku70. As a result, we have proposed a consensus RNA structure preferable for the Ku binding that is a hairpin possessing a bulge just near GpG sequence-containing terminal loop. 7SK snRNA is a scaffold for a ribonucleoprotein complex (7SK snRNP), which is known to participate in transcription regulation. We have shown that the recombinant Ku specifically binds a G-rich loop of hairpin 1 within 7SK snRNA. Moreover, Ku protein has been co-precipitated from HEK 293T cells with endogenous 7SK snRNA and such proteins included in 7SK snRNP as HEXIM1, Cdk9 and CTIP2. Ku and Cdk9 binding is found to be RNA-independent, meanwhile HEXIM1 and Ku co-precipitation depended on the presence of intact 7SK snRNA. The latter result has been confirmed using recombinant HEXIM1 and Ku proteins. Colocalization of Ku and CTIP2 was additionally confirmed by confocal microscopy. These results allow us to propose human Ku as a new component of the 7SK snRNP complex.
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Affiliation(s)
- Olga Shadrina
- Chemistry Department, Lomonosov Moscow State University, Moscow, 199991, Russia; Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119992, Moscow, Russia.
| | - Irina Garanina
- Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, Moscow, 119435, Russia
| | - Sergey Korolev
- Chemistry Department, Lomonosov Moscow State University, Moscow, 199991, Russia; Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119992, Moscow, Russia
| | - Timofei Zatsepin
- Chemistry Department, Lomonosov Moscow State University, Moscow, 199991, Russia; Skolkovo Institute of Science and Technology, Skolkovo, 121205, Russia
| | - Jeanne Van Assche
- Université de Strasbourg, EA7292, FMTS, IUT Louis Pasteur, Schiltigheim, France
| | - Fadoua Daouad
- Université de Strasbourg, EA7292, FMTS, IUT Louis Pasteur, Schiltigheim, France
| | - Clementine Wallet
- Université de Strasbourg, EA7292, FMTS, IUT Louis Pasteur, Schiltigheim, France
| | - Olivier Rohr
- Université de Strasbourg, EA7292, FMTS, IUT Louis Pasteur, Schiltigheim, France
| | - Marina Gottikh
- Chemistry Department, Lomonosov Moscow State University, Moscow, 199991, Russia; Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119992, Moscow, Russia
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Menolfi D, Zha S. ATM, ATR and DNA-PKcs kinases-the lessons from the mouse models: inhibition ≠ deletion. Cell Biosci 2020; 10:8. [PMID: 32015826 PMCID: PMC6990542 DOI: 10.1186/s13578-020-0376-x] [Citation(s) in RCA: 117] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 01/14/2020] [Indexed: 01/11/2023] Open
Abstract
DNA damage, especially DNA double strand breaks (DSBs) and replication stress, activates a complex post-translational network termed DNA damage response (DDR). Our review focuses on three PI3-kinase related protein kinases-ATM, ATR and DNA-PKcs, which situate at the apex of the mammalian DDR. They are recruited to and activated at the DNA damage sites by their respective sensor protein complexes-MRE11/RAD50/NBS1 for ATM, RPA/ATRIP for ATR and KU70-KU80/86 (XRCC6/XRCC5) for DNA-PKcs. Upon activation, ATM, ATR and DNA-PKcs phosphorylate a large number of partially overlapping substrates to promote efficient and accurate DNA repair and to coordinate DNA repair with other DNA metabolic events (e.g., transcription, replication and mitosis). At the organism level, robust DDR is critical for normal development, aging, stem cell maintenance and regeneration, and physiological genomic rearrangements in lymphocytes and germ cells. In addition to endogenous damage, oncogene-induced replication stresses and genotoxic chemotherapies also activate DDR. On one hand, DDR factors suppress genomic instability to prevent malignant transformation. On the other hand, targeting DDR enhances the therapeutic effects of anti-cancer chemotherapy, which led to the development of specific kinase inhibitors for ATM, ATR and DNA-PKcs. Using mouse models expressing kinase dead ATM, ATR and DNA-PKcs, an unexpected structural function of these kinases was revealed, where the expression of catalytically inactive kinases causes more genomic instability than the loss of the proteins themselves. The spectrum of genomic instabilities and physiological consequences are unique for each kinase and depends on their activating complexes, suggesting a model in which the catalysis is coupled with DNA/chromatin release and catalytic inhibition leads to the persistence of the kinases at the DNA lesion, which in turn affects repair pathway choice and outcomes. Here we discuss the experimental evidences supporting this mode of action and their implications in the design and use of specific kinase inhibitors for ATM, ATR and DNA-PKcs for cancer therapy.
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Affiliation(s)
- Demis Menolfi
- Institute for Cancer Genetics, College of Physicians & Surgeons, Columbia University, New York, NY 10032 USA
| | - Shan Zha
- Institute for Cancer Genetics, College of Physicians & Surgeons, Columbia University, New York, NY 10032 USA
- Department of Pathology and Cell Biology, College of Physicians & Surgeons, Columbia University, New York, NY 10032 USA
- Division of Pediatric Oncology, Hematology and Stem Cell Transplantation, Department of Pediatrics, College of Physicians & Surgeons, Columbia University, New York, NY 10032 USA
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Abbasi S, Schild-Poulter C. Mapping the Ku Interactome Using Proximity-Dependent Biotin Identification in Human Cells. J Proteome Res 2019; 18:1064-1077. [PMID: 30585729 DOI: 10.1021/acs.jproteome.8b00771] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The Ku heterodimer, composed of Ku70 and Ku80, is best characterized for its role in repairing double-stranded DNA breaks but is also known to participate in other regulatory processes. Despite our understanding of Ku protein interplay during DNA repair, the extent of Ku's protein interactions in other processes has never been fully determined. Using proximity-dependent biotin identification (BioID) and affinity purification coupled to mass spectrometry (AP-MS) with wild-type Ku70, we identified candidate proteins that interact with the Ku heterodimer in HEK293 cells, in the absence of exogenously induced DNA damage. BioID analysis identified approximately 250 nuclear proteins, appearing in at least two replicates, including known Ku-interacting factors such as MRE11A, WRN, and NCOA6. Meanwhile, AP-MS analysis identified approximately 50 candidate proteins. Of the novel protein interactors identified, many were involved in functions already suspected to involve Ku such as transcriptional regulation, DNA replication, and DNA repair, while several others suggest that Ku may be involved in additional functions such as RNA metabolism, chromatin-remodeling, and microtubule dynamics. Using a combination of BioID and AP-MS, this is the first report that comprehensively characterizes the Ku protein interaction landscape, revealing new cellular processes and protein complexes involving the Ku complex.
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Affiliation(s)
- Sanna Abbasi
- Robarts Research Institute and Department of Biochemistry, Schulich School of Medicine and Dentistry , University of Western Ontario , London , Ontario N6A 5B7 , Canada
| | - Caroline Schild-Poulter
- Robarts Research Institute and Department of Biochemistry, Schulich School of Medicine and Dentistry , University of Western Ontario , London , Ontario N6A 5B7 , Canada
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15
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Chen H, Xue J, Churikov D, Hass EP, Shi S, Lemon LD, Luciano P, Bertuch AA, Zappulla DC, Géli V, Wu J, Lei M. Structural Insights into Yeast Telomerase Recruitment to Telomeres. Cell 2017; 172:331-343.e13. [PMID: 29290466 DOI: 10.1016/j.cell.2017.12.008] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 09/27/2017] [Accepted: 12/04/2017] [Indexed: 10/18/2022]
Abstract
Telomerase maintains chromosome ends from humans to yeasts. Recruitment of yeast telomerase to telomeres occurs through its Ku and Est1 subunits via independent interactions with telomerase RNA (TLC1) and telomeric proteins Sir4 and Cdc13, respectively. However, the structures of the molecules comprising these telomerase-recruiting pathways remain unknown. Here, we report crystal structures of the Ku heterodimer and Est1 complexed with their key binding partners. Two major findings are as follows: (1) Ku specifically binds to telomerase RNA in a distinct, yet related, manner to how it binds DNA; and (2) Est1 employs two separate pockets to bind distinct motifs of Cdc13. The N-terminal Cdc13-binding site of Est1 cooperates with the TLC1-Ku-Sir4 pathway for telomerase recruitment, whereas the C-terminal interface is dispensable for binding Est1 in vitro yet is nevertheless essential for telomere maintenance in vivo. Overall, our results integrate previous models and provide fundamentally valuable structural information regarding telomere biology.
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Affiliation(s)
- Hongwen Chen
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 201210 Shanghai, China
| | - Jing Xue
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 201210 Shanghai, China
| | - Dmitri Churikov
- Marseille Cancer Research Center (CRCM), U1068 INSERM, UMR7258 CNRS, Aix Marseille University, Institut Paoli-Calmettes (Equipe labellisée Ligue), 13009 Marseille, France
| | - Evan P Hass
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Shaohua Shi
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 201210 Shanghai, China
| | - Laramie D Lemon
- Department of Pediatrics, Baylor College of Medicine, One Baylor Plaza, BCM225, Houston, TX 77030, USA
| | - Pierre Luciano
- Marseille Cancer Research Center (CRCM), U1068 INSERM, UMR7258 CNRS, Aix Marseille University, Institut Paoli-Calmettes (Equipe labellisée Ligue), 13009 Marseille, France
| | - Alison A Bertuch
- Department of Pediatrics, Baylor College of Medicine, One Baylor Plaza, BCM225, Houston, TX 77030, USA
| | - David C Zappulla
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Vincent Géli
- Marseille Cancer Research Center (CRCM), U1068 INSERM, UMR7258 CNRS, Aix Marseille University, Institut Paoli-Calmettes (Equipe labellisée Ligue), 13009 Marseille, France
| | - Jian Wu
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 201210 Shanghai, China.
| | - Ming Lei
- Shanghai Institute of Precision Medicine, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200125, China; Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, 200025 Shanghai, China.
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16
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Anisenko AN, Knyazhanskaya ES, Zatsepin TS, Gottikh MB. Human Ku70 protein binds hairpin RNA and double stranded DNA through two different sites. Biochimie 2016; 132:85-93. [PMID: 27825805 DOI: 10.1016/j.biochi.2016.11.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2016] [Accepted: 11/02/2016] [Indexed: 02/07/2023]
Abstract
Human protein Ku usually functions in the cell as a complex of two subunits, Ku70 and Ku80. The Ku heterodimer plays a key role in the non-homologous end joining DNA repair pathway by specifically recognizing the DNA ends at the site of the lesion. The binding of the Ku heterodimer to DNA has been well-studied, and its interactions with RNA have been also described. However, Ku70 subunit is known to have independent DNA binding capability, which is less characterized. RNA binding properties of Ku70 have not been yet specially studied. We have prepared recombinant full-length Ku70 and a set of its truncated mutants in E. coli, and studied their interactions with nucleic acids of various structures: linear single- and double-stranded DNA and RNA, as well as closed circular DNA and hairpin RNA. Ku70 has demonstrated a high affinity binding to double stranded DNA and hairpin RNA with a certain structure only. Interestingly, in contrast to the Ku heterodimer, Ku70 is found to interact with closed circular DNA. We also show for the first time that Ku70 employs two different sites for DNA and RNA binding. The double-stranded DNA is recognized by the C-terminal part of Ku70 including SAP domain as it has been earlier demonstrated, whereas hairpin RNA binding is provided by amino acids 251-438.
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Affiliation(s)
- Andrey N Anisenko
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russia.
| | | | - Timofey S Zatsepin
- Chemistry Department, Lomonosov Moscow State University, Moscow, Russia; Skolkovo Institute of Science and Technology, Skolkovo, Russia.
| | - Marina B Gottikh
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia.
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17
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DNA-Damage Response RNA-Binding Proteins (DDRBPs): Perspectives from a New Class of Proteins and Their RNA Targets. J Mol Biol 2016; 429:3139-3145. [PMID: 27693651 DOI: 10.1016/j.jmb.2016.09.019] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 09/21/2016] [Accepted: 09/22/2016] [Indexed: 11/23/2022]
Abstract
Upon DNA damage, cells trigger an early DNA-damage response (DDR) involving DNA repair and cell cycle checkpoints, and late responses involving gene expression regulation that determine cell fate. Screens for genes involved in the DDR have found many RNA-binding proteins (RBPs), while screens for novel RBPs have identified DDR proteins. An increasing number of RBPs are involved in early and/or late DDR. We propose to call this new class of actors of the DDR, which contain an RNA-binding activity, DNA-damage response RNA-binding proteins (DDRBPs). We then discuss how DDRBPs contribute not only to gene expression regulation in the late DDR but also to early DDR signaling, DNA repair, and chromatin modifications at DNA-damage sites through interactions with both long and short noncoding RNAs.
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18
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Lamaa A, Le Bras M, Skuli N, Britton S, Frit P, Calsou P, Prats H, Cammas A, Millevoi S. A novel cytoprotective function for the DNA repair protein Ku in regulating p53 mRNA translation and function. EMBO Rep 2016; 17:508-18. [PMID: 26964895 DOI: 10.15252/embr.201541181] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 01/27/2016] [Indexed: 12/11/2022] Open
Abstract
Ku heterodimer is a DNA binding protein with a prominent role in DNA repair. Here, we investigate whether and how Ku impacts the DNA damage response by acting as a post-transcriptional regulator of gene expression. We show that Ku represses p53 protein synthesis and p53-mediated apoptosis by binding to a bulged stem-loop structure within the p53 5' UTR However, Ku-mediated translational repression of the p53 mRNA is relieved after genotoxic stress. The underlying mechanism involves Ku acetylation which disrupts Ku-p53 mRNA interactions. These results suggest that Ku-mediated repression of p53 mRNA translation constitutes a novel mechanism linking DNA repair and mRNA translation.
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Affiliation(s)
- Assala Lamaa
- Cancer Research Center of Toulouse (CRCT), Inserm UMR 1037 Université Toulouse III-Paul Sabatier, Toulouse, France
| | - Morgane Le Bras
- Cancer Research Center of Toulouse (CRCT), Inserm UMR 1037 Université Toulouse III-Paul Sabatier, Toulouse, France
| | - Nicolas Skuli
- Cancer Research Center of Toulouse (CRCT), Inserm UMR 1037 Université Toulouse III-Paul Sabatier, Toulouse, France
| | - Sébastien Britton
- Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse, CNRS UPS, France Equipe labellisée Ligue Nationale Contre le Cancer
| | - Philippe Frit
- Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse, CNRS UPS, France Equipe labellisée Ligue Nationale Contre le Cancer
| | - Patrick Calsou
- Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse, CNRS UPS, France Equipe labellisée Ligue Nationale Contre le Cancer
| | - Hervé Prats
- Cancer Research Center of Toulouse (CRCT), Inserm UMR 1037 Université Toulouse III-Paul Sabatier, Toulouse, France
| | - Anne Cammas
- Cancer Research Center of Toulouse (CRCT), Inserm UMR 1037 Université Toulouse III-Paul Sabatier, Toulouse, France
| | - Stefania Millevoi
- Cancer Research Center of Toulouse (CRCT), Inserm UMR 1037 Université Toulouse III-Paul Sabatier, Toulouse, France
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19
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Davidovich C, Cech TR. The recruitment of chromatin modifiers by long noncoding RNAs: lessons from PRC2. RNA (NEW YORK, N.Y.) 2015; 21:2007-22. [PMID: 26574518 PMCID: PMC4647455 DOI: 10.1261/rna.053918.115] [Citation(s) in RCA: 209] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Polycomb repressive complex-2 (PRC2) is a histone methyltransferase required for epigenetic silencing during development and cancer. Among chromatin modifying factors shown to be recruited and regulated by long noncoding RNAs (lncRNAs), PRC2 is one of the most studied. Mammalian PRC2 binds thousands of RNAs in vivo, and it is becoming a model system for the recruitment of chromatin modifying factors by RNA. Yet, well-defined PRC2-binding motifs within target RNAs have been elusive. From the protein side, PRC2 RNA-binding subunits contain no known RNA-binding domains, complicating functional studies. Here we provide a critical review of existing models for the recruitment of PRC2 to chromatin by RNAs. This discussion may also serve researchers who are studying the recruitment of other chromatin modifiers by lncRNAs.
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Affiliation(s)
- Chen Davidovich
- BioFrontiers Institute and Howard Hughes Medical Institute, University of Colorado, Boulder, Colorado 80309, USA
| | - Thomas R Cech
- BioFrontiers Institute and Howard Hughes Medical Institute, University of Colorado, Boulder, Colorado 80309, USA
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20
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Hass EP, Zappulla DC. The Ku subunit of telomerase binds Sir4 to recruit telomerase to lengthen telomeres in S. cerevisiae. eLife 2015. [PMID: 26218225 PMCID: PMC4547093 DOI: 10.7554/elife.07750] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
In Saccharomyces cerevisiae and in humans, the telomerase RNA subunit is bound by Ku, a ring-shaped protein heterodimer best known for its function in DNA repair. Ku binding to yeast telomerase RNA promotes telomere lengthening and telomerase recruitment to telomeres, but how this is achieved remains unknown. Using telomere-length analysis and chromatin immunoprecipitation, we show that Sir4 – a previously identified Ku-binding protein that is a component of telomeric silent chromatin – is required for Ku-mediated telomere lengthening and telomerase recruitment. We also find that specifically tethering Sir4 directly to Ku-binding-defective telomerase RNA restores otherwise-shortened telomeres to wild-type length. These findings suggest that Sir4 is the telomere-bound target of Ku-mediated telomerase recruitment and provide one mechanism for how the Sir4-competing Rif1 and Rif2 proteins negatively regulate telomere length in yeast. DOI:http://dx.doi.org/10.7554/eLife.07750.001 Inside a cell's nucleus, DNA is packaged into structures called chromosomes. The ends of every chromosome are capped by repeating sequences of DNA known as telomeres, which protect the chromosomes from damage. Every time a cell divides, the telomeres shorten. If telomere length falls below a critical level, the cell can die or enter a state in which it can no longer divide. During cell division, an enzyme called telomerase normally restores telomeres to their original length. Telomerase is made up of several proteins and an RNA molecule. In yeast and humans, a protein called Ku is one part of the telomerase enzyme. Ku binds to the RNA subunit of telomerase and helps the enzyme find and interact with the telomeres. Previous research has shown that Ku is unable to work alone to recruit telomerase to the chromosome. A protein called Sir4 binds to telomeres and cells lacking it have short telomeres, but the reason behind this was not known. Hass and Zappulla confirmed previous reports that Ku binds to Sir4 using a biochemical approach. Additional experiments provided genetic evidence that this binding interaction is important for telomerase to lengthen telomeres appropriately. Cells in which the RNA subunit of telomerase is unable to bind effectively to Ku have short telomeres. Hass and Zappulla directly tethered Sir4 to this defective RNA and found this restored the shortened telomeres to a normal length, indicating that Sir4 normally binds Ku to recruit telomerase. Discovering this mode of recruitment also helps to explain how two other telomeric proteins (Rif1 and 2) limit telomere lengthening; they compete with Ku-Sir4 recruitment to form a length-regulating system. Taken together, Hass and Zappulla's results provide strong evidence that Sir4 cooperates with Ku to control the lengthening of chromosome ends. Future research will hopefully reveal the precise space and time requirements for this telomerase-controlling system in yeast. Additionally, because Ku has been reported to be a subunit of human telomerase, future studies could also explore whether human cells use a similar strategy. DOI:http://dx.doi.org/10.7554/eLife.07750.002
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Affiliation(s)
- Evan P Hass
- Department of Biology, Johns Hopkins University, Baltimore, United States
| | - David C Zappulla
- Department of Biology, Johns Hopkins University, Baltimore, United States
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21
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Lebo KJ, Niederer RO, Zappulla DC. A second essential function of the Est1-binding arm of yeast telomerase RNA. RNA (NEW YORK, N.Y.) 2015; 21:862-876. [PMID: 25737580 PMCID: PMC4408794 DOI: 10.1261/rna.049379.114] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 12/29/2014] [Indexed: 06/04/2023]
Abstract
The enzymatic ribonucleoprotein telomerase maintains telomeres in many eukaryotes, including humans, and plays a central role in aging and cancer. Saccharomyces cerevisiae telomerase RNA, TLC1, is a flexible scaffold that tethers telomerase holoenzyme protein subunits to the complex. Here we test the hypothesis that a lengthy conserved region of the Est1-binding TLC1 arm contributes more than simply Est1-binding function. We separated Est1 binding from potential other functions by tethering TLC1 to Est1 via a heterologous RNA-protein binding module. We find that Est1-tethering rescues in vivo function of telomerase RNA alleles missing nucleotides specifically required for Est1 binding, but not those missing the entire conserved region. Notably, however, telomerase function is restored for this condition by expressing the arm of TLC1 in trans. Mutational analysis shows that the Second Essential Est1-arm Domain (SEED) maps to an internal loop of the arm, which SHAPE chemical mapping and 3D modeling suggest could be regulated by conformational change. Finally, we find that the SEED has an essential, Est1-independent role in telomerase function after telomerase recruitment to the telomere. The SEED may be required for establishing telomere extendibility or promoting telomerase RNP holoenzyme activity.
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Affiliation(s)
- Kevin J Lebo
- Department of Biology, Johns Hopkins University, Baltimore, Maryland 21218-2685, USA
| | - Rachel O Niederer
- Department of Biology, Johns Hopkins University, Baltimore, Maryland 21218-2685, USA
| | - David C Zappulla
- Department of Biology, Johns Hopkins University, Baltimore, Maryland 21218-2685, USA
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22
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Davidovich C, Wang X, Cifuentes-Rojas C, Goodrich KJ, Gooding AR, Lee JT, Cech TR. Toward a consensus on the binding specificity and promiscuity of PRC2 for RNA. Mol Cell 2015; 57:552-8. [PMID: 25601759 DOI: 10.1016/j.molcel.2014.12.017] [Citation(s) in RCA: 165] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 10/23/2014] [Accepted: 12/06/2014] [Indexed: 01/23/2023]
Abstract
Polycomb repressive complex-2 (PRC2) is a histone methyltransferase required for epigenetic silencing during development and cancer. Early works suggested binding specificity of PRC2 to certain long non-coding RNAs for recruitment to chromatin. More recent studies provided evidence both in favor and against this idea. Here, we bridge the two existing models of PRC2-RNA interaction. RepA RNA is a good binding partner for PRC2, while multiple non-relevant RNAs, including bacterial mRNAs, also bind PRC2; Kds depend to some extent on the experimental conditions. Human and mouse PRC2 have broadly similar RNA-binding properties in vitro. Examination of evidence supporting an existing model for site-specific recruitment of PRC2 by a well-defined RNA motif in cells reveals that results are PRC2 independent. We conclude that promiscuous and specific RNA-binding activities of PRC2 in vitro are not mutually exclusive, and that binding specificity in vivo remains to be demonstrated.
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Affiliation(s)
- Chen Davidovich
- Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, BioFrontiers Institute, University of Colorado, Boulder, CO 80309, USA
| | - Xueyin Wang
- Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, BioFrontiers Institute, University of Colorado, Boulder, CO 80309, USA
| | - Catherine Cifuentes-Rojas
- Howard Hughes Medical Institute, Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Karen J Goodrich
- Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, BioFrontiers Institute, University of Colorado, Boulder, CO 80309, USA
| | - Anne R Gooding
- Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, BioFrontiers Institute, University of Colorado, Boulder, CO 80309, USA
| | - Jeannie T Lee
- Howard Hughes Medical Institute, Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA.
| | - Thomas R Cech
- Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, BioFrontiers Institute, University of Colorado, Boulder, CO 80309, USA.
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Phelps KJ, Tran K, Eifler T, Erickson AI, Fisher AJ, Beal PA. Recognition of duplex RNA by the deaminase domain of the RNA editing enzyme ADAR2. Nucleic Acids Res 2015; 43:1123-32. [PMID: 25564529 PMCID: PMC4333395 DOI: 10.1093/nar/gku1345] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Adenosine deaminases acting on RNA (ADARs) hydrolytically deaminate adenosines (A) in a wide variety of duplex RNAs and misregulation of editing is correlated with human disease. However, our understanding of reaction selectivity is limited. ADARs are modular enzymes with multiple double-stranded RNA binding domains (dsRBDs) and a catalytic domain. While dsRBD binding is understood, little is known about ADAR catalytic domain/RNA interactions. Here we use a recently discovered RNA substrate that is rapidly deaminated by the isolated human ADAR2 deaminase domain (hADAR2-D) to probe these interactions. We introduced the nucleoside analog 8-azanebularine (8-azaN) into this RNA (and derived constructs) to mechanistically trap the protein–RNA complex without catalytic turnover for EMSA and ribonuclease footprinting analyses. EMSA showed that hADAR2-D requires duplex RNA and is sensitive to 2′-deoxy substitution at nucleotides opposite the editing site, the local sequence and 8-azaN nucleotide positioning on the duplex. Ribonuclease V1 footprinting shows that hADAR2-D protects ∼23 nt on the edited strand around the editing site in an asymmetric fashion (∼18 nt on the 5′ side and ∼5 nt on the 3′ side). These studies provide a deeper understanding of the ADAR catalytic domain–RNA interaction and new tools for biophysical analysis of ADAR–RNA complexes.
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Affiliation(s)
- Kelly J Phelps
- Department of Chemistry, University of California, One Shields Avenue, Davis, CA 95616, USA
| | - Kiet Tran
- Department of Chemistry, University of California, One Shields Avenue, Davis, CA 95616, USA
| | - Tristan Eifler
- Department of Chemistry, University of California, One Shields Avenue, Davis, CA 95616, USA
| | - Anna I Erickson
- Department of Molecular and Cellular Biology, University of California, One Shields Avenue, Davis, CA 95616, USA
| | - Andrew J Fisher
- Department of Chemistry, University of California, One Shields Avenue, Davis, CA 95616, USA Department of Molecular and Cellular Biology, University of California, One Shields Avenue, Davis, CA 95616, USA
| | - Peter A Beal
- Department of Chemistry, University of California, One Shields Avenue, Davis, CA 95616, USA
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Malyavko AN, Parfenova YY, Zvereva MI, Dontsova OA. Telomere length regulation in budding yeasts. FEBS Lett 2014; 588:2530-6. [PMID: 24914478 DOI: 10.1016/j.febslet.2014.05.049] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Revised: 05/23/2014] [Accepted: 05/23/2014] [Indexed: 11/19/2022]
Abstract
Telomeres are the nucleoprotein caps of chromosomes. Their length must be tightly regulated in order to maintain the stability of the genome. This is achieved by the intricate network of interactions between different proteins and protein-RNA complexes. Different organisms use various mechanisms for telomere length homeostasis. However, details of these mechanisms are not yet completely understood. In this review we have summarized our latest achievements in the understanding of telomere length regulation in budding yeasts.
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Affiliation(s)
- Alexander N Malyavko
- Faculty of Chemistry, Lomonosov Moscow State University, 119999 Moscow, Russia; Belozersky Institute, Moscow State University, Leninskie Gory 1, Bldg. 40, 119991 Moscow, Russia
| | - Yuliya Y Parfenova
- Faculty of Chemistry, Lomonosov Moscow State University, 119999 Moscow, Russia; Belozersky Institute, Moscow State University, Leninskie Gory 1, Bldg. 40, 119991 Moscow, Russia
| | - Maria I Zvereva
- Faculty of Chemistry, Lomonosov Moscow State University, 119999 Moscow, Russia; Belozersky Institute, Moscow State University, Leninskie Gory 1, Bldg. 40, 119991 Moscow, Russia
| | - Olga A Dontsova
- Faculty of Chemistry, Lomonosov Moscow State University, 119999 Moscow, Russia; Belozersky Institute, Moscow State University, Leninskie Gory 1, Bldg. 40, 119991 Moscow, Russia.
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