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Fu Y, Sacco O, DeBitetto E, Kanshin E, Ueberheide B, Sfeir A. Mitochondrial DNA breaks activate an integrated stress response to reestablish homeostasis. Mol Cell 2023; 83:3740-3753.e9. [PMID: 37832546 DOI: 10.1016/j.molcel.2023.09.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 08/10/2023] [Accepted: 09/21/2023] [Indexed: 10/15/2023]
Abstract
Mitochondrial DNA double-strand breaks (mtDSBs) lead to the degradation of circular genomes and a reduction in copy number; yet, the cellular response in human cells remains elusive. Here, using mitochondrial-targeted restriction enzymes, we show that a subset of cells with mtDSBs exhibited defective mitochondrial protein import, reduced respiratory complexes, and loss of membrane potential. Electron microscopy confirmed the altered mitochondrial membrane and cristae ultrastructure. Intriguingly, mtDSBs triggered the integrated stress response (ISR) via the phosphorylation of eukaryotic translation initiation factor 2α (eIF2α) by DELE1 and heme-regulated eIF2α kinase (HRI). When ISR was inhibited, the cells experienced intensified mitochondrial defects and slower mtDNA recovery post-breakage. Lastly, through proteomics, we identified ATAD3A-a membrane-bound protein interacting with nucleoids-as potentially pivotal in relaying signals from impaired genomes to the inner mitochondrial membrane. In summary, our study delineates the cascade connecting damaged mitochondrial genomes to the cytoplasm and highlights the significance of the ISR in maintaining mitochondrial homeostasis amid genome instability.
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Affiliation(s)
- Yi Fu
- Skirball Institute of Biomolecular Medicine, Cell Biology Department, NYU School of Medicine, New York, NY 10016, USA; Molecular Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Olivia Sacco
- Molecular Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Emily DeBitetto
- Molecular Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Evgeny Kanshin
- Proteomics Laboratory, NYU School of Medicine, New York, NY 10016, USA; Biochemistry and Molecular Pharmacology, NYU School of Medicine, New York, NY 10016, USA
| | - Beatrix Ueberheide
- Proteomics Laboratory, NYU School of Medicine, New York, NY 10016, USA; Biochemistry and Molecular Pharmacology, NYU School of Medicine, New York, NY 10016, USA; Department of Neurology, NYU School of Medicine, New York, NY 10016, USA; Perlmutter Cancer Center, NYU School of Medicine, New York, NY 10016, USA
| | - Agnel Sfeir
- Molecular Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA.
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2
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Brambati A, Sacco O, Porcella S, Heyza J, Kareh M, Schmidt JC, Sfeir A. RHINO directs MMEJ to repair DNA breaks in mitosis. Science 2023; 381:653-660. [PMID: 37440612 PMCID: PMC10561558 DOI: 10.1126/science.adh3694] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 06/30/2023] [Indexed: 07/15/2023]
Abstract
Nonhomologous end-joining (NHEJ) and homologous recombination (HR) are the primary pathways for repairing DNA double-strand breaks (DSBs) during interphase, whereas microhomology-mediated end-joining (MMEJ) has been regarded as a backup mechanism. Through CRISPR-Cas9-based synthetic lethal screens in cancer cells, we identified subunits of the 9-1-1 complex (RAD9A-RAD1-HUS1) and its interacting partner, RHINO, as crucial MMEJ factors. We uncovered an unexpected function for RHINO in restricting MMEJ to mitosis. RHINO accumulates in M phase, undergoes Polo-like kinase 1 (PLK1) phosphorylation, and interacts with polymerase θ (Polθ), enabling its recruitment to DSBs for subsequent repair. Additionally, we provide evidence that MMEJ activity in mitosis repairs persistent DSBs that originate in S phase. Our findings offer insights into the synthetic lethal relationship between the genes POLQ and BRCA1 and BRAC2 and the synergistic effect of Polθ and poly(ADP-ribose) polymerase (PARP) inhibitors.
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Affiliation(s)
- Alessandra Brambati
- Molecular Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center; New York, NY, USA
| | - Olivia Sacco
- Molecular Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center; New York, NY, USA
| | - Sarina Porcella
- Molecular Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center; New York, NY, USA
| | - Joshua Heyza
- Institute for Quantitative Health Sciences and Engineering, Michigan State University; East Lansing, MI, USA
- Department of Obstetrics, Gynecology, and Reproductive Biology, Michigan State University; East Lansing, MI, USA
| | - Mike Kareh
- Molecular Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center; New York, NY, USA
| | - Jens C. Schmidt
- Institute for Quantitative Health Sciences and Engineering, Michigan State University; East Lansing, MI, USA
- Department of Obstetrics, Gynecology, and Reproductive Biology, Michigan State University; East Lansing, MI, USA
| | - Agnel Sfeir
- Molecular Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center; New York, NY, USA
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3
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Oh G, Wang A, Wang L, Li J, Werba G, Weissinger D, Zhao E, Dhara S, Hernandez RE, Ackermann A, Porcella S, Kalfakakou D, Dolgalev I, Kawaler E, Golan T, Welling TH, Sfeir A, Simeone DM. POLQ inhibition elicits an immune response in homologous recombination-deficient pancreatic adenocarcinoma via cGAS/STING signaling. J Clin Invest 2023; 133:e165934. [PMID: 36976649 PMCID: PMC10232002 DOI: 10.1172/jci165934] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 03/22/2023] [Indexed: 03/29/2023] Open
Abstract
Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal malignancy that harbors mutations in homologous recombination-repair (HR-repair) proteins in 20%-25% of cases. Defects in HR impart a specific vulnerability to poly ADP ribose polymerase inhibitors and platinum-containing chemotherapy in tumor cells. However, not all patients who receive these therapies respond, and many who initially respond ultimately develop resistance. Inactivation of the HR pathway is associated with the overexpression of polymerase theta (Polθ, or POLQ). This key enzyme regulates the microhomology-mediated end-joining (MMEJ) pathway of double-strand break (DSB) repair. Using human and murine HR-deficient PDAC models, we found that POLQ knockdown is synthetically lethal in combination with mutations in HR genes such as BRCA1 and BRCA2 and the DNA damage repair gene ATM. Further, POLQ knockdown enhances cytosolic micronuclei formation and activates signaling of cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING), leading to enhanced infiltration of activated CD8+ T cells in BRCA2-deficient PDAC tumors in vivo. Overall, POLQ, a key mediator in the MMEJ pathway, is critical for DSB repair in BRCA2-deficient PDAC. Its inhibition represents a synthetic lethal approach to blocking tumor growth while concurrently activating the cGAS-STING signaling pathway to enhance tumor immune infiltration, highlighting what we believe to be a new role for POLQ in the tumor immune environment.
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Affiliation(s)
| | | | - Lidong Wang
- Perlmutter Cancer Center, NYU Langone Health, New York, New York, USA
| | - Jiufeng Li
- Perlmutter Cancer Center, NYU Langone Health, New York, New York, USA
| | - Gregor Werba
- Perlmutter Cancer Center, NYU Langone Health, New York, New York, USA
| | - Daniel Weissinger
- Perlmutter Cancer Center, NYU Langone Health, New York, New York, USA
| | - Ende Zhao
- Perlmutter Cancer Center, NYU Langone Health, New York, New York, USA
| | - Surajit Dhara
- Perlmutter Cancer Center, NYU Langone Health, New York, New York, USA
| | | | - Amanda Ackermann
- Perlmutter Cancer Center, NYU Langone Health, New York, New York, USA
| | - Sarina Porcella
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York, USA
| | | | - Igor Dolgalev
- Department of Pathology, NYU Langone Health, New York, New York, USA
| | - Emily Kawaler
- Perlmutter Cancer Center, NYU Langone Health, New York, New York, USA
| | | | | | - Agnel Sfeir
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York, USA
| | - Diane M. Simeone
- Department of Surgery and
- Perlmutter Cancer Center, NYU Langone Health, New York, New York, USA
- Department of Pathology, NYU Langone Health, New York, New York, USA
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4
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Brambati A, Sacco O, Porcella S, Heyza J, Kareh M, Schmidt JC, Sfeir A. RHINO restricts MMEJ activity to mitosis. bioRxiv 2023:2023.03.16.532763. [PMID: 36993461 PMCID: PMC10055031 DOI: 10.1101/2023.03.16.532763] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
DNA double-strand breaks (DSBs) are toxic lesions that can lead to genome instability if not properly repaired. Breaks incurred in G1 phase of the cell cycle are predominantly fixed by non-homologous end-joining (NHEJ), while homologous recombination (HR) is the primary repair pathway in S and G2. Microhomology-mediated end-joining (MMEJ) is intrinsically error-prone and considered a backup DSB repair pathway that becomes essential when HR and NHEJ are compromised. In this study, we uncover MMEJ as the major DSB repair pathway in M phase. Using CRISPR/Cas9-based synthetic lethal screens, we identify subunits of the 9-1-1 complex (RAD9A-HUS1-RAD1) and its interacting partner, RHINO, as critical MMEJ factors. Mechanistically, we show that the function of 9-1-1 and RHINO in MMEJ is inconsistent with their well-established role in ATR signaling. Instead, RHINO plays an unexpected and essential role in directing mutagenic repair to M phase by directly binding to Polymerase theta (Polθ) and promoting its recruitment to DSBs in mitosis. In addition, we provide evidence that mitotic MMEJ repairs persistent DNA damage that originates in S phase but is not repaired by HR. The latter findings could explain the synthetic lethal relationship between POLQ and BRCA1/2 and the synergistic effect of Polθ and PARP inhibitors. In summary, our study identifies MMEJ as the primary pathway for repairing DSBs during mitosis and highlights an unanticipated role for RHINO in directing mutagenic repair to M phase.
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5
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Bubenik M, Mader P, Mochirian P, Vallée F, Clark J, Truchon JF, Perryman AL, Pau V, Kurinov I, Zahn KE, Leclaire ME, Papp R, Mathieu MC, Hamel M, Duffy NM, Godbout C, Casas-Selves M, Falgueyret JP, Baruah PS, Nicolas O, Stocco R, Poirier H, Martino G, Fortin AB, Roulston A, Chefson A, Dorich S, St-Onge M, Patel P, Pellerin C, Ciblat S, Pinter T, Barabé F, Bakkouri ME, Parikh P, Gervais C, Sfeir A, Mamane Y, Morris SJ, Black WC, Sicheri F, Gallant M. Identification of RP-6685, an Orally Bioavailable Compound that Inhibits the DNA Polymerase Activity of Polθ. J Med Chem 2022; 65:13198-13215. [PMID: 36126059 PMCID: PMC9942948 DOI: 10.1021/acs.jmedchem.2c00998] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
DNA polymerase theta (Polθ) is an attractive synthetic lethal target for drug discovery, predicted to be efficacious against breast and ovarian cancers harboring BRCA-mutant alleles. Here, we describe our hit-to-lead efforts in search of a selective inhibitor of human Polθ (encoded by POLQ). A high-throughput screening campaign of 350,000 compounds identified an 11 micromolar hit, giving rise to the N2-substituted fused pyrazolo series, which was validated by biophysical methods. Structure-based drug design efforts along with optimization of cellular potency and ADME ultimately led to the identification of RP-6685: a potent, selective, and orally bioavailable Polθ inhibitor that showed in vivo efficacy in an HCT116 BRCA2-/- mouse tumor xenograft model.
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Affiliation(s)
- Monica Bubenik
- Repare Therapeutics, 7171 Frederick-Banting, Building 2, H4S 1Z9, Montréal, Québec, Canada
| | - Pavel Mader
- Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, Ontario, M5G 1X5, Canada
| | - Philippe Mochirian
- Repare Therapeutics, 7171 Frederick-Banting, Building 2, H4S 1Z9, Montréal, Québec, Canada
| | - Fréderic Vallée
- Repare Therapeutics, 7171 Frederick-Banting, Building 2, H4S 1Z9, Montréal, Québec, Canada
| | - Jillian Clark
- Repare Therapeutics, 7171 Frederick-Banting, Building 2, H4S 1Z9, Montréal, Québec, Canada
| | - Jean-François Truchon
- Repare Therapeutics, 7171 Frederick-Banting, Building 2, H4S 1Z9, Montréal, Québec, Canada
| | - Alexander L. Perryman
- Repare Therapeutics, 7171 Frederick-Banting, Building 2, H4S 1Z9, Montréal, Québec, Canada
| | - Victor Pau
- Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, Ontario, M5G 1X5, Canada
| | - Igor Kurinov
- Department of Chemistry and Chemical Biology, Cornell University, NE-CAT, Argonne, Illinois 60439, USA
| | - Karl E. Zahn
- Repare Therapeutics, 7171 Frederick-Banting, Building 2, H4S 1Z9, Montréal, Québec, Canada
| | - Marie-Eve Leclaire
- Repare Therapeutics, 7171 Frederick-Banting, Building 2, H4S 1Z9, Montréal, Québec, Canada
| | - Robert Papp
- Repare Therapeutics, 7171 Frederick-Banting, Building 2, H4S 1Z9, Montréal, Québec, Canada
| | - Marie-Claude Mathieu
- Repare Therapeutics, 7171 Frederick-Banting, Building 2, H4S 1Z9, Montréal, Québec, Canada
| | - Martine Hamel
- Repare Therapeutics, 7171 Frederick-Banting, Building 2, H4S 1Z9, Montréal, Québec, Canada
| | - Nicole M. Duffy
- Repare Therapeutics, 7171 Frederick-Banting, Building 2, H4S 1Z9, Montréal, Québec, Canada
| | - Claude Godbout
- Repare Therapeutics, 7171 Frederick-Banting, Building 2, H4S 1Z9, Montréal, Québec, Canada
| | - Matias Casas-Selves
- Repare Therapeutics, 7171 Frederick-Banting, Building 2, H4S 1Z9, Montréal, Québec, Canada
| | - Jean-Pierre Falgueyret
- Repare Therapeutics, 7171 Frederick-Banting, Building 2, H4S 1Z9, Montréal, Québec, Canada
| | - Prasamit S. Baruah
- Repare Therapeutics, 7171 Frederick-Banting, Building 2, H4S 1Z9, Montréal, Québec, Canada
| | - Olivier Nicolas
- Repare Therapeutics, 7171 Frederick-Banting, Building 2, H4S 1Z9, Montréal, Québec, Canada
| | - Rino Stocco
- Repare Therapeutics, 7171 Frederick-Banting, Building 2, H4S 1Z9, Montréal, Québec, Canada
| | - Hugo Poirier
- Repare Therapeutics, 7171 Frederick-Banting, Building 2, H4S 1Z9, Montréal, Québec, Canada
| | - Giovanni Martino
- Repare Therapeutics, 7171 Frederick-Banting, Building 2, H4S 1Z9, Montréal, Québec, Canada
| | | | - Anne Roulston
- Repare Therapeutics, 7171 Frederick-Banting, Building 2, H4S 1Z9, Montréal, Québec, Canada
| | - Amandine Chefson
- Ventus Therapeutics 7150 Frederick-Banting suite 200, Montréal, Québec, H4S 2A1, Canada
| | - Stéphane Dorich
- Ventus Therapeutics 7150 Frederick-Banting suite 200, Montréal, Québec, H4S 2A1, Canada
| | - Miguel St-Onge
- Ventus Therapeutics 7150 Frederick-Banting suite 200, Montréal, Québec, H4S 2A1, Canada
| | - Purvish Patel
- Ventus Therapeutics 7150 Frederick-Banting suite 200, Montréal, Québec, H4S 2A1, Canada
| | - Charles Pellerin
- Ventus Therapeutics 7150 Frederick-Banting suite 200, Montréal, Québec, H4S 2A1, Canada
| | - Stéphane Ciblat
- Ventus Therapeutics 7150 Frederick-Banting suite 200, Montréal, Québec, H4S 2A1, Canada
- Paraza Pharma Inc., 2525 Ave. Marie Curie, Montréal, Québec, H4S 1Z9, Canada
| | - Thomas Pinter
- Paraza Pharma Inc., 2525 Ave. Marie Curie, Montréal, Québec, H4S 1Z9, Canada
| | - Francis Barabé
- Paraza Pharma Inc., 2525 Ave. Marie Curie, Montréal, Québec, H4S 1Z9, Canada
| | - Majida El Bakkouri
- Paraza Pharma Inc., 2525 Ave. Marie Curie, Montréal, Québec, H4S 1Z9, Canada
- National Research Council of Canada, 6100 Royalmount Ave, Montréal, Québec, H4P 2R2, Canada
| | - Paranjay Parikh
- Piramal Pharma Ltd., Plot No. 18, Village Matoda, Taluka: Sanand, Ahmedabad-382213, Gujarat, India
| | - Christian Gervais
- National Research Council of Canada, 6100 Royalmount Ave, Montréal, Québec, H4P 2R2, Canada
| | - Agnel Sfeir
- Molecular Biology Program, Sloan Kettering Institute, MSKCC, 430 E 67th Street, New York, NY 10065, USA
| | - Yael Mamane
- Repare Therapeutics, 7171 Frederick-Banting, Building 2, H4S 1Z9, Montréal, Québec, Canada
| | - Stephen J. Morris
- Repare Therapeutics, 7171 Frederick-Banting, Building 2, H4S 1Z9, Montréal, Québec, Canada
| | - W. Cameron Black
- Repare Therapeutics, 7171 Frederick-Banting, Building 2, H4S 1Z9, Montréal, Québec, Canada
| | - Frank Sicheri
- Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, Ontario, M5G 1X5, Canada
| | - Michel Gallant
- Repare Therapeutics, 7171 Frederick-Banting, Building 2, H4S 1Z9, Montréal, Québec, Canada
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6
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Barry RM, Sacco O, Mameri A, Stojaspal M, Kartsonis W, Shah P, De Ioannes P, Hofr C, Côté J, Sfeir A. Rap1 regulates TIP60 function during fate transition between two-cell-like and pluripotent states. Genes Dev 2022; 36:313-330. [PMID: 35210222 PMCID: PMC8973845 DOI: 10.1101/gad.349039.121] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 02/08/2022] [Indexed: 01/05/2023]
Abstract
In mammals, the conserved telomere binding protein Rap1 serves a diverse set of nontelomeric functions, including activation of the NF-kB signaling pathway, maintenance of metabolic function in vivo, and transcriptional regulation. Here, we uncover the mechanism by which Rap1 modulates gene expression. Using a separation-of-function allele, we show that Rap1 transcriptional regulation is largely independent of TRF2-mediated binding to telomeres and does not involve direct binding to genomic loci. Instead, Rap1 interacts with the TIP60/p400 complex and modulates its histone acetyltransferase activity. Notably, we show that deletion of Rap1 in mouse embryonic stem cells increases the fraction of two-cell-like cells. Specifically, Rap1 enhances the repressive activity of Tip60/p400 across a subset of two-cell-stage genes, including Zscan4 and the endogenous retrovirus MERVL. Preferential up-regulation of genes proximal to MERVL elements in Rap1-deficient settings implicates these endogenous retroviral elements in the derepression of proximal genes. Altogether, our study reveals an unprecedented link between Rap1 and the TIP60/p400 complex in the regulation of pluripotency.
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Affiliation(s)
- Raymond Mario Barry
- Skirball Institute of Biomolecular Medicine, Department of Cell Biology, New York University School of Medicine, New York, New York 10016, USA.,Molecular Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
| | - Olivia Sacco
- Molecular Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
| | - Amel Mameri
- St-Patrick Research Group in Basic Oncology; CHU de Québec-Université Laval Research Center-Oncology Division, Laval University Cancer Research Center, Quebec City, Quebec G1R 3S3, Canada
| | - Martin Stojaspal
- Skirball Institute of Biomolecular Medicine, Department of Cell Biology, New York University School of Medicine, New York, New York 10016, USA.,LifeB, Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, 625 00 Brno, Czech Republic
| | - William Kartsonis
- Skirball Institute of Biomolecular Medicine, Department of Cell Biology, New York University School of Medicine, New York, New York 10016, USA
| | - Pooja Shah
- Skirball Institute of Biomolecular Medicine, Department of Cell Biology, New York University School of Medicine, New York, New York 10016, USA
| | - Pablo De Ioannes
- Skirball Institute of Biomolecular Medicine, Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, New York 10016, USA
| | - Ctirad Hofr
- LifeB, Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, 625 00 Brno, Czech Republic.,Institute of Biophysics of the Czech Academy of Sciences, Scientific Incubator, 612 65 Brno, Czech Republic
| | - Jacques Côté
- St-Patrick Research Group in Basic Oncology; CHU de Québec-Université Laval Research Center-Oncology Division, Laval University Cancer Research Center, Quebec City, Quebec G1R 3S3, Canada
| | - Agnel Sfeir
- Molecular Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
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7
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Sfeir A, Fishell G, Schier AF, Dustin ML, Gan WB, Joyner A, Lehmann R, Ron D, Roth D, Talbot WS, Yelon D, Zychlinsky A. Basic science under threat: Lessons from the Skirball Institute. Cell 2022; 185:755-758. [DOI: 10.1016/j.cell.2022.02.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 02/03/2022] [Accepted: 02/04/2022] [Indexed: 11/28/2022]
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8
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Penev A, Bazley A, Shen M, Boeke JD, Savage SA, Sfeir A. Alternative splicing is a developmental switch for hTERT expression. Mol Cell 2021; 81:2349-2360.e6. [PMID: 33852895 PMCID: PMC8943697 DOI: 10.1016/j.molcel.2021.03.033] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 03/17/2021] [Accepted: 03/19/2021] [Indexed: 01/02/2023]
Abstract
Telomere length control is critical for cellular lifespan and tumor suppression. Telomerase is transiently activated in the inner cell mass of the developing blastocyst to reset telomere reserves. Its silencing upon differentiation leads to gradual telomere shortening in somatic cells. Here, we report that transcriptional regulation through cis-regulatory elements only partially accounts for telomerase activation in pluripotent cells. Instead, developmental control of telomerase is primarily driven by an alternative splicing event, centered around hTERT exon 2. Skipping of exon 2 triggers hTERT mRNA decay in differentiated cells, and conversely, its retention promotes telomerase accumulation in pluripotent cells. We identify SON as a regulator of exon 2 alternative splicing and report a patient carrying a SON mutation and suffering from insufficient telomerase and short telomeres. In summary, our study highlights a critical role for hTERT alternative splicing in the developmental regulation of telomerase and implicates defective splicing in telomere biology disorders.
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Affiliation(s)
- Alex Penev
- Skirball Institute of Biomolecular Medicine, Department of Cell Biology, NYU School of Medicine, New York, NY 10016, USA
| | - Andrew Bazley
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology, NYU Langone Health, New York, NY 10016, USA
| | - Michael Shen
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology, NYU Langone Health, New York, NY 10016, USA
| | - Jef D Boeke
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology, NYU Langone Health, New York, NY 10016, USA; Department of Biomedical Engineering, NYU Tandon School of Engineering, Brooklyn, NY 11201, USA
| | - Sharon A Savage
- Clinical Genetics Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, MD 20892, USA
| | - Agnel Sfeir
- Skirball Institute of Biomolecular Medicine, Department of Cell Biology, NYU School of Medicine, New York, NY 10016, USA.
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9
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Chartrand P, Sfeir A. A single-molecule view of telomerase regulation at telomeres. Mol Cell Oncol 2020; 7:1818537. [PMID: 33241110 DOI: 10.1080/23723556.2020.1818537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Telomerase plays a key role in the immortalization of cancer cells by maintaining telomeres length. Using single-molecule imaging of telomerase RNA molecules in cancer cells, we recently reported novel insights into the role of Cajal bodies in telomerase biogenesis and the regulation of telomerase recruitment to telomeres.
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Affiliation(s)
- Pascal Chartrand
- Department of Biochemistry and Molecular Medicine, Université De Montréal, Montréal, Qc, Canada
| | - Agnel Sfeir
- Skirball Institute of Biomolecular Medicine, NYU School of Medicine, New York, NY, USA
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10
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Abstract
Advances in imaging technologies, gene editing, and fluorescent molecule development have made real-time imaging of nucleic acids practical. Here, we detail methods for imaging the human telomerase RNA template, hTR via the use of three inserted MS2 stem loops and cognate MS2 coat protein (MCP) tagged with superfolder GFP or photoactivatable GFP. These technologies enable tracking of the dynamics of RNA species through Cajal bodies and offer insight into their residence time in Cajal bodies through photobleaching and photoactivation experiments. For complete details on the use and execution of this protocol, please refer to Laprade et al. (2020).
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Affiliation(s)
- Michael Smith
- Skirball Institute of Biomolecular Medicine, Department of Cell Biology, NYU Grossman School of Medicine, New York, NY 10016, USA
| | - Emmanuelle Querido
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Canada
| | - Pascal Chartrand
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Canada
| | - Agnel Sfeir
- Skirball Institute of Biomolecular Medicine, Department of Cell Biology, NYU Grossman School of Medicine, New York, NY 10016, USA
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11
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Querido E, Sfeir A, Chartrand P. Imaging of Telomerase RNA by Single-Molecule Inexpensive FISH Combined with Immunofluorescence. STAR Protoc 2020; 1:100104. [PMID: 33111129 PMCID: PMC7580239 DOI: 10.1016/j.xpro.2020.100104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Fluorescent in situ hybridization (FISH) on the RNA moiety of human telomerase (hTR) with 50-mer probes detects hTR RNA accumulated in Cajal bodies. Using both live-cell imaging and single-molecule inexpensive FISH, our published work revealed that only a fraction of hTR localizes to Cajal bodies, with the majority of hTR molecules distributed throughout the nucleoplasm. This protocol is an application guide to the smiFISH method for the dual detection of hTR RNA and telomeres or Cajal bodies by immunofluorescence. For complete details on the use and execution of this protocol, please refer to Laprade et al. (2020). RNA smiFISH with multiple small probes reveals single molecules of hTR RNA in nucleus The smiFISH technique is compatible with immunofluorescence for colocalization assay Colocalized regions can be mapped in 3D images with the open source 3D ImageJ Suite
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Affiliation(s)
- Emmanuelle Querido
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, QC H3C 3J7, Canada
| | - Agnel Sfeir
- Skirball Institute of Biomolecular Medicine, Cell Biology Department, NYU School of Medicine, New York, NY 10016, USA
| | - Pascal Chartrand
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, QC H3C 3J7, Canada
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12
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Abstract
Mitochondria respond to DNA damage and preserve their own genetic material in a manner distinct from that of the nucleus but that requires organized mito-nuclear communication. Failure to resolve mtDNA breaks leads to mitochondrial dysfunction and affects host cells and tissues. Here, we review the pathways that safeguard mitochondrial genomes and examine the insights gained from studies of cellular and tissue-wide responses to mtDNA damage and mito-nuclear genome incompatibility.
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Affiliation(s)
- Yi Fu
- Skirball Institute of Biomolecular Medicine, Cell Biology Department, NYU Grossman School of Medicine, New York, NY, USA
| | - Marco Tigano
- Skirball Institute of Biomolecular Medicine, Cell Biology Department, NYU Grossman School of Medicine, New York, NY, USA
| | - Agnel Sfeir
- Skirball Institute of Biomolecular Medicine, Cell Biology Department, NYU Grossman School of Medicine, New York, NY, USA.
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13
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Tigano M, Phillips AF, Sfeir A. Single-molecule analysis of mtDNA replication with high resolution. Methods Cell Biol 2020; 155:401-414. [PMID: 32183970 DOI: 10.1016/bs.mcb.2019.10.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
DNA combing technology is a powerful methodology for the study of DNA replication in vivo. This tool can be used to identify origins of replication, assess of directionality of forks, and measure fork speed. Over the years, the method has been used extensively to study nuclear DNA replication. The first step involves the incorporation of thymidine analogs (CldU and IdU) into nascent DNA chains and followed by their visualization with immunofluorescence using antibodies that can distinguish the two analogs. Recently, we adapted and fine-tuned DNA combing technology to the specifics of mitochondrial DNA (Phillips et al., 2017, p. 155). The protocol, which we termed mito-SMARD (mitochondrial single molecule analysis of replication DNA), provides in vivo insight into mitochondrial DNA (mtDNA) replication with high resolution.
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Affiliation(s)
- Marco Tigano
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, Department of Developmental Genetics, New York, NY, United States
| | - Aaron Fraser Phillips
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, Department of Developmental Genetics, New York, NY, United States
| | - Agnel Sfeir
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, Department of Developmental Genetics, New York, NY, United States.
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14
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Brambati A, Barry RM, Sfeir A. DNA polymerase theta (Polθ) - an error-prone polymerase necessary for genome stability. Curr Opin Genet Dev 2020; 60:119-126. [PMID: 32302896 PMCID: PMC7230004 DOI: 10.1016/j.gde.2020.02.017] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 02/13/2020] [Accepted: 02/14/2020] [Indexed: 12/21/2022]
Abstract
Mammalian cells have evolved multiple pathways to repair DNA double strand breaks (DSBs) and ensure genome stability. In addition to non-homologous end-joining (NHEJ) and homologous recombination (HR), cells evolved an error-prone repair pathway termed microhomology-mediated end joining (MMEJ). The mutagenic outcome of MMEJ derives from the activity of DNA polymerase theta (Polθ) - a multidomain enzyme that is minimally expressed in normal tissue but overexpressed in tumors. Polθ expression is particularly crucial for the proliferation of HR deficient cancer cells. As a result, this mutagenic repair emerged as an attractive target for cancer therapy, and inhibitors are currently in pre-clinical development. Here, we review the multifunctionality of this enigmatic polymerase, focusing on its role during DSB repair in mammalian cells and its impact on cancer genomes.
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Affiliation(s)
- Alessandra Brambati
- Skirball Institute of Biomolecular Medicine, Department of Cell Biology, NYU School of Medicine, New York, NY 10016, USA
| | - Raymond Mario Barry
- Skirball Institute of Biomolecular Medicine, Department of Cell Biology, NYU School of Medicine, New York, NY 10016, USA
| | - Agnel Sfeir
- Skirball Institute of Biomolecular Medicine, Department of Cell Biology, NYU School of Medicine, New York, NY 10016, USA.
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15
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Wang A, Zamperone A, Sohail M, Wang L, Balogun F, Li J, Zhao E, Diolaiti D, Sfeir A, Simeone DM. Abstract I14: Polymerase theta synthetic lethal interaction in homologous recombination-deficient pancreatic ductal adenocarcinoma. Cancer Res 2019. [DOI: 10.1158/1538-7445.panca19-i14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Recent genomic characterization of PDA reveals that between 20-25 % of PDA harbor recurrent mutations in genes, including BRCA1/2, PALB2, and ATM, which are critical for homologous recombination (HR), an important form of DNA repair. In many patients, these may be germline mutations. This subgroup of PDAs, termed HR-deficient PDA, has emerged as a defined biological entity associated with increased chemoresistance and a more aggressive disease course. The defects in HR observed in these tumors impart cells with a specific vulnerability to PARP inhibitors and platinum-containing therapy. Still, as observed in the case of many other targeted therapies, only a fraction of HR-defective patient tumors respond to PARP inhibition. More so, many patients that initially respond eventually often develop resistance and progress. Therefore, novel therapies which can be effective against HR-defective PDA, alone or in combination with PARP inhibitors or other combinatorial regimens, are urgently needed. We have recently determined that inactivation of the HR pathway is associated with overexpression of polymerase theta (PolO–, also known as POLQ) in PDA. POLQ is a key enzyme that regulates an alternative pathway of DNA repair, known as the alternative non-homologous end-joining (Alt-NHEJ) pathway. In the setting of defective HR, Alt-NHEJ becomes a critical pathway responsible for the repair of DNA breaks and POLQ inhibition in HR-defective tumor cells demonstrates a synthetic lethality phenotype, not observed in cells with intact HR. Furthermore, POLQ knockdown significantly upregulated the cGAS-STING pathway in HR-deficient PDAs linking the DNA damage response to the immune response. Overall, targeting POLQ may represent a novel and in a valuable therapeutic strategy in HR-defective pancreatic cancer, as POLQ inhibitors are currently in development for clinical use.
Citation Format: Annie Wang, Andrea Zamperone, Mohammad Sohail, Lidong Wang, Fiyinfolu Balogun, Jiufeng Li, Ende Zhao, Daniel Diolaiti, Agnel Sfeir, Diane M. Simeone. Polymerase theta synthetic lethal interaction in homologous recombination-deficient pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2019 Sept 6-9; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2019;79(24 Suppl):Abstract nr I14.
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Affiliation(s)
- Annie Wang
- 1NYU Langone Health, Laura & Isaac Perlmutter Cancer Center, New York, NY
| | - Andrea Zamperone
- 1NYU Langone Health, Laura & Isaac Perlmutter Cancer Center, New York, NY
| | - Mohammad Sohail
- 1NYU Langone Health, Laura & Isaac Perlmutter Cancer Center, New York, NY
| | - Lidong Wang
- 1NYU Langone Health, Laura & Isaac Perlmutter Cancer Center, New York, NY
| | - Fiyinfolu Balogun
- 1NYU Langone Health, Laura & Isaac Perlmutter Cancer Center, New York, NY
| | - Jiufeng Li
- 1NYU Langone Health, Laura & Isaac Perlmutter Cancer Center, New York, NY
| | - Ende Zhao
- 1NYU Langone Health, Laura & Isaac Perlmutter Cancer Center, New York, NY
| | - Daniel Diolaiti
- 1NYU Langone Health, Laura & Isaac Perlmutter Cancer Center, New York, NY
| | - Agnel Sfeir
- 2NYU Langone Health, Skirball Institute of Biomolecular Medicine, New York, NY
| | - Diane M. Simeone
- 1NYU Langone Health, Laura & Isaac Perlmutter Cancer Center, New York, NY
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16
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Mateos-Gomez PA, Kent T, Deng SK, McDevitt S, Kashkina E, Hoang TM, Pomerantz RT, Sfeir A. The helicase domain of Polθ counteracts RPA to promote alt-NHEJ. Nat Struct Mol Biol 2017; 24:1116-1123. [PMID: 29058711 PMCID: PMC6047744 DOI: 10.1038/nsmb.3494] [Citation(s) in RCA: 111] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Accepted: 09/22/2017] [Indexed: 12/15/2022]
Abstract
Mammalian polymerase theta (Polθ) is a multifunctional enzyme that promotes error-prone DNA repair by alternative nonhomologous end joining (alt-NHEJ). Here we present structure-function analyses that reveal that, in addition to the polymerase domain, Polθ-helicase activity plays a central role during double-strand break (DSB) repair. Our results show that the helicase domain promotes chromosomal translocations by alt-NHEJ in mouse embryonic stem cells and also suppresses CRISPR-Cas9- mediated gene targeting by homologous recombination (HR). In vitro assays demonstrate that Polθ-helicase activity facilitates the removal of RPA from resected DSBs to allow their annealing and subsequent joining by alt-NHEJ. Consistent with an antagonistic role for RPA during alt-NHEJ, inhibition of RPA1 enhances end joining and suppresses recombination. Taken together, our results reveal that the balance between HR and alt-NHEJ is controlled by opposing activities of Polθ and RPA, providing further insight into the regulation of repair-pathway choice in mammalian cells.
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Affiliation(s)
- Pedro A. Mateos-Gomez
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, USA
- Department of Cell Biology, New York University School of Medicine, New York, USA
| | - Tatiana Kent
- Temple University Lewis Katz School of Medicine, Philadelphia, USA
| | - Sarah K. Deng
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, USA
- Department of Cell Biology, New York University School of Medicine, New York, USA
| | - Shane McDevitt
- Temple University Lewis Katz School of Medicine, Philadelphia, USA
| | | | - Trung M. Hoang
- Temple University Lewis Katz School of Medicine, Philadelphia, USA
| | | | - Agnel Sfeir
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, USA
- Department of Cell Biology, New York University School of Medicine, New York, USA
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17
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Phillips AF, Millet AR, Tigano M, Dubois SM, Crimmins H, Babin L, Charpentier M, Piganeau M, Brunet E, Sfeir A. Single-Molecule Analysis of mtDNA Replication Uncovers the Basis of the Common Deletion. Mol Cell 2017; 65:527-538.e6. [PMID: 28111015 DOI: 10.1016/j.molcel.2016.12.014] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2016] [Revised: 10/04/2016] [Accepted: 12/16/2016] [Indexed: 11/30/2022]
Abstract
Mutations in mtDNA lead to muscular and neurological diseases and are linked to aging. The most frequent aberrancy is the "common deletion" that involves a 4,977-bp region flanked by 13-bp repeats. To investigate the basis of this deletion, we developed a single-molecule mtDNA combing method. The analysis of replicating mtDNA molecules provided in vivo evidence in support of the asymmetric mode of replication. Furthermore, we observed frequent fork stalling at the junction of the common deletion, suggesting that impaired replication triggers the formation of this toxic lesion. In parallel experiments, we employed mito-TALENs to induce breaks in distinct loci of the mitochondrial genome and found that breaks adjacent to the 5' repeat trigger the common deletion. Interestingly, this process was mediated by the mitochondrial replisome independent of canonical DSB repair. Altogether, our data underscore a unique replication-dependent repair pathway that leads to the mitochondrial common deletion.
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Affiliation(s)
- Aaron F Phillips
- Skirball Institute of Biomolecular Medicine, Department of Cell Biology, NYU School of Medicine, New York, NY 10016, USA
| | - Armêl R Millet
- Structure et Instabilité des Génomes, Muséum National d'Histoire Naturelle, INSERM U 1154, CNRS UMR 7196, 75005 Paris, France; Genome Dynamics in the Immune System Laboratory, INSERM, UMR 1163, Institut Imagine, 75015 Paris, France
| | - Marco Tigano
- Skirball Institute of Biomolecular Medicine, Department of Cell Biology, NYU School of Medicine, New York, NY 10016, USA
| | - Sonia M Dubois
- Structure et Instabilité des Génomes, Muséum National d'Histoire Naturelle, INSERM U 1154, CNRS UMR 7196, 75005 Paris, France
| | - Hannah Crimmins
- Skirball Institute of Biomolecular Medicine, Department of Cell Biology, NYU School of Medicine, New York, NY 10016, USA
| | - Loelia Babin
- Structure et Instabilité des Génomes, Muséum National d'Histoire Naturelle, INSERM U 1154, CNRS UMR 7196, 75005 Paris, France; Genome Dynamics in the Immune System Laboratory, INSERM, UMR 1163, Institut Imagine, 75015 Paris, France
| | - Marine Charpentier
- Structure et Instabilité des Génomes, Muséum National d'Histoire Naturelle, INSERM U 1154, CNRS UMR 7196, 75005 Paris, France
| | - Marion Piganeau
- Structure et Instabilité des Génomes, Muséum National d'Histoire Naturelle, INSERM U 1154, CNRS UMR 7196, 75005 Paris, France
| | - Erika Brunet
- Structure et Instabilité des Génomes, Muséum National d'Histoire Naturelle, INSERM U 1154, CNRS UMR 7196, 75005 Paris, France; Genome Dynamics in the Immune System Laboratory, INSERM, UMR 1163, Institut Imagine, 75015 Paris, France.
| | - Agnel Sfeir
- Skirball Institute of Biomolecular Medicine, Department of Cell Biology, NYU School of Medicine, New York, NY 10016, USA.
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18
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Kent T, Mateos-Gomez PA, Sfeir A, Pomerantz RT. Polymerase θ is a robust terminal transferase that oscillates between three different mechanisms during end-joining. eLife 2016; 5:e13740. [PMID: 27311885 PMCID: PMC4912351 DOI: 10.7554/elife.13740] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Accepted: 05/12/2016] [Indexed: 12/18/2022] Open
Abstract
DNA polymerase θ (Polθ) promotes insertion mutations during alternative end-joining (alt-EJ) by an unknown mechanism. Here, we discover that mammalian Polθ transfers nucleotides to the 3' terminus of DNA during alt-EJ in vitro and in vivo by oscillating between three different modes of terminal transferase activity: non-templated extension, templated extension in cis, and templated extension in trans. This switching mechanism requires manganese as a co-factor for Polθ template-independent activity and allows for random combinations of templated and non-templated nucleotide insertions. We further find that Polθ terminal transferase activity is most efficient on DNA containing 3' overhangs, is facilitated by an insertion loop and conserved residues that hold the 3' primer terminus, and is surprisingly more proficient than terminal deoxynucleotidyl transferase. In summary, this report identifies an unprecedented switching mechanism used by Polθ to generate genetic diversity during alt-EJ and characterizes Polθ as among the most proficient terminal transferases known.
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Affiliation(s)
- Tatiana Kent
- Fels Institute for Cancer Research, Temple University Lewis Katz School of Medicine, Philadelphia, United States
- Department of Medical Genetics and Molecular Biochemistry, Temple University Lewis Katz School of Medicine, Philadelphia, United States
| | - Pedro A Mateos-Gomez
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, United States
- Department of Cell Biology, New York University School of Medicine, New York, United States
| | - Agnel Sfeir
- Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, United States
- Department of Cell Biology, New York University School of Medicine, New York, United States
| | - Richard T Pomerantz
- Fels Institute for Cancer Research, Temple University Lewis Katz School of Medicine, Philadelphia, United States
- Department of Medical Genetics and Molecular Biochemistry, Temple University Lewis Katz School of Medicine, Philadelphia, United States
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19
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Pinzaru AM, Hom RA, Beal A, Phillips AF, Ni E, Cardozo T, Nair N, Choi J, Wuttke DS, Sfeir A, Denchi EL. Telomere Replication Stress Induced by POT1 Inactivation Accelerates Tumorigenesis. Cell Rep 2016; 15:2170-2184. [PMID: 27239034 PMCID: PMC6145145 DOI: 10.1016/j.celrep.2016.05.008] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Revised: 02/19/2016] [Accepted: 04/22/2016] [Indexed: 01/05/2023] Open
Abstract
Genome sequencing studies have revealed a number of cancer-associated mutations in the telomerebinding factor POT1. Here, we show that when combined with p53 deficiency, depletion of murine POT1a in common lymphoid progenitor cells fosters genetic instability, accelerates the onset, and increases the severity of T cell lymphomas. In parallel, we examined human and mouse cells carrying POT1 mutations found in cutaneous T cell lymphoma (CTCL) patients. Inhibition of POT1 activates ATRdependent DNA damage signaling and induces telomere fragility, replication fork stalling, and telomere elongation. Our data suggest that these phenotypes are linked to impaired CST (CTC1-STN1-TEN1) function at telomeres. Lastly, we show that proliferation of cancer cells lacking POT1 is enabled by the attenuation of the ATR kinase pathway. These results uncover a role for defective telomere replication during tumorigenesis. Pinzaru et al. define a role for POT1 inactivation in the onset of thymic lymphomas. Inhibition of POT1 causes replication defects at telomeres resulting in telomere fragility, replication fork stalling, and genome instability. These results suggest a role of defective telemore replication during tumorigenesis
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Affiliation(s)
- Alexandra M Pinzaru
- Department of Cell Biology, Skirball Institute of Biomolecular Medicine, NYU School of Medicine, New York, NY 10016, USA
| | - Robert A Hom
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309, USA
| | - Angela Beal
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Aaron F Phillips
- Department of Cell Biology, Skirball Institute of Biomolecular Medicine, NYU School of Medicine, New York, NY 10016, USA
| | - Eric Ni
- Department of Biochemistry and Molecular Pharmacology, NYU School of Medicine, New York, NY 10016, USA
| | - Timothy Cardozo
- Department of Biochemistry and Molecular Pharmacology, NYU School of Medicine, New York, NY 10016, USA
| | - Nidhi Nair
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Jaehyuk Choi
- Departments of Dermatology and Biochemistry and Molecular Genetics, Northwestern University, Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Deborah S Wuttke
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309, USA
| | - Agnel Sfeir
- Department of Cell Biology, Skirball Institute of Biomolecular Medicine, NYU School of Medicine, New York, NY 10016, USA.
| | - Eros Lazzerini Denchi
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA.
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20
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Tong AS, Stern JL, Sfeir A, Kartawinata M, de Lange T, Zhu XD, Bryan TM. ATM and ATR Signaling Regulate the Recruitment of Human Telomerase to Telomeres. Cell Rep 2015; 13:1633-46. [PMID: 26586433 DOI: 10.1016/j.celrep.2015.10.041] [Citation(s) in RCA: 94] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Revised: 09/14/2015] [Accepted: 10/16/2015] [Indexed: 01/06/2023] Open
Abstract
The yeast homologs of the ATM and ATR DNA damage response kinases play key roles in telomerase-mediated telomere maintenance, but the role of ATM/ATR in the mammalian telomerase pathway has been less clear. Here, we demonstrate the requirement for ATM and ATR in the localization of telomerase to telomeres and telomere elongation in immortal human cells. Stalled replication forks increased telomerase recruitment in an ATR-dependent manner. Furthermore, increased telomerase recruitment was observed upon phosphorylation of the shelterin component TRF1 at an ATM/ATR target site (S367). This phosphorylation leads to loss of TRF1 from telomeres and may therefore increase replication fork stalling. ATM and ATR depletion reduced assembly of the telomerase complex, and ATM was required for telomere elongation in cells expressing POT1ΔOB, an allele of POT1 that disrupts telomere-length homeostasis. These data establish that human telomerase recruitment and telomere elongation are modulated by DNA-damage-transducing kinases.
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Affiliation(s)
- Adrian S Tong
- Cell Biology Unit, Children's Medical Research Institute, University of Sydney, Westmead, NSW 2145, Australia
| | - J Lewis Stern
- Cell Biology Unit, Children's Medical Research Institute, University of Sydney, Westmead, NSW 2145, Australia
| | - Agnel Sfeir
- Laboratory for Cell Biology and Genetics, The Rockefeller University, New York, NY 10065, USA
| | - Melissa Kartawinata
- Cell Biology Unit, Children's Medical Research Institute, University of Sydney, Westmead, NSW 2145, Australia
| | - Titia de Lange
- Laboratory for Cell Biology and Genetics, The Rockefeller University, New York, NY 10065, USA
| | - Xu-Dong Zhu
- Department of Biology, McMaster University, Hamilton, ON L8S 4K1, Canada
| | - Tracy M Bryan
- Cell Biology Unit, Children's Medical Research Institute, University of Sydney, Westmead, NSW 2145, Australia.
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21
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Mateos-Gomez PA, Gong F, Nair N, Miller KM, Lazzerini-Denchi E, Sfeir A. Mammalian polymerase θ promotes alternative NHEJ and suppresses recombination. Nature 2015; 518:254-7. [PMID: 25642960 PMCID: PMC4718306 DOI: 10.1038/nature14157] [Citation(s) in RCA: 495] [Impact Index Per Article: 55.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Accepted: 12/16/2014] [Indexed: 12/11/2022]
Abstract
The alternative non-homologous end-joining (NHEJ) machinery facilitates several genomic rearrangements, some of which can lead to cellular transformation. This error-prone repair pathway is triggered upon telomere de-protection to promote the formation of deleterious chromosome end-to-end fusions. Using next-generation sequencing technology, here we show that repair by alternative NHEJ yields non-TTAGGG nucleotide insertions at fusion breakpoints of dysfunctional telomeres. Investigating the enzymatic activity responsible for the random insertions enabled us to identify polymerase theta (Polθ; encoded by Polq in mice) as a crucial alternative NHEJ factor in mammalian cells. Polq inhibition suppresses alternative NHEJ at dysfunctional telomeres, and hinders chromosomal translocations at non-telomeric loci. In addition, we found that loss of Polq in mice results in increased rates of homology-directed repair, evident by recombination of dysfunctional telomeres and accumulation of RAD51 at double-stranded breaks. Lastly, we show that depletion of Polθ has a synergistic effect on cell survival in the absence of BRCA genes, suggesting that the inhibition of this mutagenic polymerase represents a valid therapeutic avenue for tumours carrying mutations in homology-directed repair genes.
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Affiliation(s)
- Pedro A. Mateos-Gomez
- Skirball Institute of Biomolecular Medicine, Department of Cell Biology, NYU School of Medicine, New York, NY 10016, USA
| | - Fade Gong
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, University of Texas at Austin. 2506 Speedway Stop A5000, Austin, TX 78712 USA
| | - Nidhi Nair
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Kyle M. Miller
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, University of Texas at Austin. 2506 Speedway Stop A5000, Austin, TX 78712 USA
| | - Eros Lazzerini-Denchi
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Agnel Sfeir
- Skirball Institute of Biomolecular Medicine, Department of Cell Biology, NYU School of Medicine, New York, NY 10016, USA
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22
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Abstract
Spermatogenesis is a complex process that generates haploid germ cells or spores and implements meiosis, a succession of two special cell divisions that are required for homologous chromosome segregation. During prophase to the first meiotic division, homologous recombination (HR) repairs Spo11-dependent DNA double-strand breaks (DSBs) in the presence of telomere movements to allow for chromosome pairing and segregation at the meiosis I division. In contrast to HR, non-homologous end joining (NHEJ), the major DSB repair mechanism during the G1 cell cycle phase, is downregulated during early meiotic prophase. At somatic mammalian telomeres, the NHEJ factor Ku70/80 inhibits HR, as does the Rap1 component of the shelterin complex. Here, we investigated the role of Ku70 and Rap1 in meiotic telomere redistribution and genome protection in spermatogenesis by studying single and double knockout mice. Ku70(-/-) mice display reduced testis size and compromised spermatogenesis, whereas meiotic telomere dynamics and chromosomal bouquet formation occurred normally in Ku70(-/-) and Ku70(-/-)Rap1(Δ/Δ) knockout spermatocytes. Elevated mid-preleptotene frequencies were associated with significantly increased DNA damage in Ku-deficient B spermatogonia, and in differentiated Sertoli cells. Significantly elevated levels of γH2AX foci in Ku70(-/-) diplotene spermatocytes suggest compromised progression of DNA repair at a subset of DSBs. This might explain the elevated meiotic metaphase apoptosis that is present in Ku70-deficient stage XII testis tubules, indicating spindle assembly checkpoint activation. In summary, our data indicate that Ku70 is important for repairing DSBs in somatic cells and in late spermatocytes of the testis, thereby assuring the fidelity of spermatogenesis.
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Affiliation(s)
- Emad A Ahmed
- Institut für Radiobiologie der Bundeswehr in Verbindung mit der Universität, Ulm, Neuherbergstrasse 1, D-80937 München, Germany
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23
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Yeung F, Ramírez CM, Mateos-Gomez PA, Pinzaru A, Ceccarini G, Kabir S, Fernández-Hernando C, Sfeir A. Nontelomeric role for Rap1 in regulating metabolism and protecting against obesity. Cell Rep 2013; 3:1847-56. [PMID: 23791522 DOI: 10.1016/j.celrep.2013.05.032] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Revised: 04/16/2013] [Accepted: 05/21/2013] [Indexed: 11/15/2022] Open
Abstract
The mammalian telomere-binding protein Rap1 was recently found to have additional nontelomeric functions, acting as a transcriptional cofactor and a regulator of the NF-κB pathway. Here, we assess the effect of disrupting mouse Rap1 in vivo and report on its unanticipated role in metabolic regulation and body-weight homeostasis. Rap1 inhibition causes dysregulation in hepatic as well as adipose function, leading to glucose intolerance, insulin resistance, liver steatosis, and excess fat accumulation. Furthermore, Rap1 appears to play a pivotal role in the transcriptional cascade that controls adipocyte differentiation in vitro. Using a separation-of-function allele, we show that the metabolic function of Rap1 is independent of its recruitment to TTAGGG binding elements found at telomeres and at other interstitial loci. In conclusion, our study underscores an additional function for the most conserved telomere-binding protein, forging a link between telomere biology and metabolic signaling.
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Affiliation(s)
- Frank Yeung
- The Helen L. and Martin S. Kimmel Center for Biology and Medicine, Skirball Institute of Biomolecular Medicine, Department of Cell Biology, NYU School of Medicine, New York, NY 10016, USA
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24
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Affiliation(s)
- Agnel Sfeir
- The Helen L and Martin S Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, Department of Cell Biology, NYU School of Medicine, New York, NY 10016, USA.
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Abstract
The choice between double-strand break (DSB) repair by either homology-directed repair (HDR) or nonhomologous end joining (NHEJ) is tightly regulated. Defects in this regulation can induce genome instability and cancer. 53BP1 is critical for the control of DSB repair, promoting NHEJ, and inhibiting the 5' end resection needed for HDR. Using dysfunctional telomeres and genome-wide DSBs, we identify Rif1 as the main factor used by 53BP1 to impair 5' end resection. Rif1 inhibits resection involving CtIP, BLM, and Exo1; limits accumulation of BRCA1/BARD1 complexes at sites of DNA damage; and defines one of the mechanisms by which 53BP1 causes chromosomal abnormalities in Brca1-deficient cells. These data establish Rif1 as an important contributor to the control of DSB repair by 53BP1.
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Affiliation(s)
- Michal Zimmermann
- Laboratory for Cell Biology and Genetics, Rockefeller University, New York, NY 10065, USA
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26
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Abstract
The telomere end-protection problem is defined by the aggregate of DNA damage signaling and repair pathways that require repression at telomeres. To define the end-protection problem, we removed the whole shelterin complex from mouse telomeres through conditional deletion of TRF1 and TRF2 in nonhomologous end-joining (NHEJ) deficient cells. The data reveal two DNA damage response pathways not previously observed upon deletion of individual shelterin proteins. The shelterin-free telomeres are processed by microhomology-mediated alternative-NHEJ when Ku70/80 is absent and are attacked by nucleolytic degradation in the absence of 53BP1. The data establish that the end-protection problem is specified by six pathways [ATM (ataxia telangiectasia mutated) and ATR (ataxia telangiectasia and Rad3 related) signaling, classical-NHEJ, alt-NHEJ, homologous recombination, and resection] and show how shelterin acts with general DNA damage response factors to solve this problem.
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Affiliation(s)
- Agnel Sfeir
- Laboratory for Cell Biology and Genetics, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
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27
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Abstract
The telomere end-protection problem is defined by the aggregate of DNA damage signaling and repair pathways that require repression at telomeres. To define the end-protection problem, we removed the whole shelterin complex from mouse telomeres through conditional deletion of TRF1 and TRF2 in nonhomologous end-joining (NHEJ) deficient cells. The data reveal two DNA damage response pathways not previously observed upon deletion of individual shelterin proteins. The shelterin-free telomeres are processed by microhomology-mediated alternative-NHEJ when Ku70/80 is absent and are attacked by nucleolytic degradation in the absence of 53BP1. The data establish that the end-protection problem is specified by six pathways [ATM (ataxia telangiectasia mutated) and ATR (ataxia telangiectasia and Rad3 related) signaling, classical-NHEJ, alt-NHEJ, homologous recombination, and resection] and show how shelterin acts with general DNA damage response factors to solve this problem.
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Affiliation(s)
- Agnel Sfeir
- Laboratory for Cell Biology and Genetics, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
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28
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Abstract
Mammalian Rap1, a TRF2-interacting protein in the telomeric shelterin complex, was recently shown to repress homology-directed repair at chromosome ends. In addition, Rap1 plays a role in transcriptional regulation and NFκB signaling. Rap1 is unique among the components of shelterin in that it is conserved in budding yeast and has non-telomeric functions. Comparison of mammalian Rap1 to the Rap1 proteins of several budding yeasts and fission yeast reveal both striking similarities and notable differences. The protean nature of Rap1 is best understood by viewing it as an adaptor that can mediate a variety of protein-protein and protein-DNA interactions depending on the organism and the complex in which it is functioning.
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Affiliation(s)
- Shaheen Kabir
- Laboratory for Cell Biology and Genetics, The Rockefeller University, New York, NY, USA
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29
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Scherthan H, Sfeir A, de Lange T. Rap1-independent telomere attachment and bouquet formation in mammalian meiosis. Chromosoma 2010; 120:151-7. [PMID: 20927532 DOI: 10.1007/s00412-010-0295-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2010] [Revised: 09/16/2010] [Accepted: 09/20/2010] [Indexed: 11/28/2022]
Abstract
Attachment of telomeres to the nuclear envelope (NE) and their clustering in a chromosomal bouquet during meiotic prophase I is an evolutionary conserved event that promotes chromosome pairing and recombination. In fission yeast, bouquet formation fails when the telomeric protein Rap1 is absent or when the telomeric protein Taz1 fails to recruit Rap1 to telomeres. The mammalian Rap1 orthologue is a component of the shelterin complex and localises to telomeres through an interaction with a Taz1-like telomeric DNA binding factor, TRF2. Here, we investigated the role of mammalian Rap1 in meiotic telomere attachment and clustering by analysing spermatogenesis in Rap1-deficient mice. The results establish that the meiotic three-dimensional nuclear architecture and recombination are not affected by the absence of Rap1. Furthermore, Rap1-deficient meiotic telomeres assemble the SUN1 nuclear membrane protein, attach to the NE, and undergo bouquet formation indistinguishable from the wild-type setting. Thus, the role of Rap1 in meiosis is not conserved between fission yeast and mammals, suggesting that mammals have alternative modes for connecting telomeres to SUN proteins on the meiotic nuclear envelope.
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Affiliation(s)
- Harry Scherthan
- Institut für Radiobiologie der Bundeswehr in Verbindung mit der Universität Ulm, Neuherbergstr. 11, 80937, Munich, Germany.
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30
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Sfeir A, Kabir S, van Overbeek M, Celli GB, de Lange T. Loss of Rap1 induces telomere recombination in the absence of NHEJ or a DNA damage signal. Science 2010; 327:1657-61. [PMID: 20339076 DOI: 10.1126/science.1185100] [Citation(s) in RCA: 196] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Shelterin is an essential telomeric protein complex that prevents DNA damage signaling and DNA repair at mammalian chromosome ends. Here we report on the role of the TRF2-interacting factor Rap1, a conserved shelterin subunit of unknown function. We removed Rap1 from mouse telomeres either through gene deletion or by replacing TRF2 with a mutant that does not bind Rap1. Rap1 was dispensable for the essential functions of TRF2--repression of ATM kinase signaling and nonhomologous end joining (NHEJ)--and mice lacking telomeric Rap1 were viable and fertile. However, Rap1 was critical for the repression of homology-directed repair (HDR), which can alter telomere length. The data reveal that HDR at telomeres can take place in the absence of DNA damage foci and underscore the functional compartmentalization within shelterin.
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Affiliation(s)
- Agnel Sfeir
- The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
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31
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Sfeir A, Kosiyatrakul ST, Hockemeyer D, MacRae SL, Karlseder J, Schildkraut CL, de Lange T. Mammalian telomeres resemble fragile sites and require TRF1 for efficient replication. Cell 2009; 138:90-103. [PMID: 19596237 DOI: 10.1016/j.cell.2009.06.021] [Citation(s) in RCA: 746] [Impact Index Per Article: 49.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2009] [Revised: 05/19/2009] [Accepted: 06/11/2009] [Indexed: 01/26/2023]
Abstract
Telomeres protect chromosome ends through the interaction of telomeric repeats with shelterin, a protein complex that represses DNA damage signaling and DNA repair reactions. The telomeric repeats are maintained by telomerase, which solves the end replication problem. We report that the TTAGGG repeat arrays of mammalian telomeres pose a challenge to the DNA replication machinery, giving rise to replication-dependent defects that resemble those of aphidicolin-induced common fragile sites. Gene deletion experiments showed that efficient duplication of telomeres requires the shelterin component TRF1. Without TRF1, telomeres activate the ATR kinase in S phase and show a fragile-site phenotype in metaphase. Single-molecule analysis of replicating telomeres showed that TRF1 promotes efficient replication of TTAGGG repeats and prevents fork stalling. Two helicases implicated in the removal of G4 DNA structures, BLM and RTEL1, were required to repress the fragile-telomere phenotype. These results identify a second telomere replication problem that is solved by the shelterin component TRF1.
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Affiliation(s)
- Agnel Sfeir
- Laboratory for Cell Biology and Genetics, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
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Talhouk RS, Elble RC, Bassam R, Daher M, Sfeir A, Mosleh LA, El-Khoury H, Hamoui S, Pauli BU, El-Sabban ME. Developmental expression patterns and regulation of connexins in the mouse mammary gland: expression of connexin30 in lactogenesis. Cell Tissue Res 2005; 319:49-59. [PMID: 15517403 DOI: 10.1007/s00441-004-0915-5] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2004] [Accepted: 05/07/2004] [Indexed: 11/24/2022]
Abstract
The mammary gland reaches a fully differentiated phenotype at lactation, a stage characterized by the abundant expression of beta-casein. We have investigated the expression and regulation of gap junction proteins (connexins, Cx) during the various developmental stages of mouse mammary gland. Immunohistochemical analysis, with specific antibodies, reveals that Cx26 and Cx32 are expressed and confined to the cell borders of luminal epithelial cells in all developmental stages of the gland. Cx26 and Cx32 expression, at the mRNA and protein levels, increases in pregnancy and peaks in lactation. Whereas Cx43 mRNA decreases in pregnancy and lactation, the functional activity of Cx43 protein, which has been localized to myoepithelial cells, is regulated (through phosphorylation) during pregnancy and peaks during lactation. Cx30 mRNA and proteins have, for the first time, been detected in mammary gland epithelia. Using reverse transcription/polymerase chain reaction and sequencing techniques, we show that Cx30 is abundant in pregnant and lactating mammary gland. Cx30 protein levels have not been detected in the mammary gland prior to day 15 of pregnancy, whereas maximum expression occurs at the onset of lactation. In mouse mammary cells in culture, Cx30 is epithelial-cell-specific and is induced by lactogenic hormones. These data identify a novel player in mammary differentiation and suggest a potential role for Cx30 in the fully differentiated gland.
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Affiliation(s)
- Rabih S Talhouk
- Department of Biology, Faculty of Arts and Sciences, American University of Beirut, PO Box 11-0236, Beirut, Lebanon.
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33
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Abstract
The proliferative life span of human cells is limited by telomere shortening, but the specific telomeres responsible for determining the onset of senescence have not been adequately determined. We here identify the shortest telomeres by the frequency of signal-free ends after in situ hybridization with telomeric probes and demonstrate that probes adjacent to the shortest ends colocalize with gammaH2AX-positive DNA damage foci in senescent cells. Normal BJ cells growth arrest at senescence before developing significant karyotypic abnormalities. We also identify all of the telomeres involved in end-associations in BJ fibroblasts whose cell-cycle arrest at the time of replicative senescence has been blocked and demonstrate that the 10% of the telomeres with the shortest ends are involved in >90% of all end-associations. The failure to find telomeric end-associations in near-senescent normal BJ metaphases, the presence of signal-free ends in 90% of near-senescent metaphases, and the colocalization of short telomeres with DNA damage foci in senescent interphase cells suggests that end-associations rather than damage signals from short telomeres per se may be the proximate cause of growth arrest. These results demonstrate that a specific group of chromosomes with the shortest telomeres rather than either all or only one or two sentinel telomeres is responsible for the induction of replicative senescence.
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Affiliation(s)
- Ying Zou
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
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35
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Sfeir A, Piché C, Lazar A. [Fever of unknown origin. Case report]. Union Med Can 1980; 109:1075-6. [PMID: 6258275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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