51
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Escandell JM, Carvalho ES, Gallo-Fernandez M, Reis CC, Matmati S, Luís IM, Abreu IA, Coulon S, Ferreira MG. Ssu72 phosphatase is a conserved telomere replication terminator. EMBO J 2019; 38:embj.2018100476. [PMID: 30796050 PMCID: PMC6443209 DOI: 10.15252/embj.2018100476] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 01/21/2019] [Accepted: 01/28/2019] [Indexed: 01/31/2023] Open
Abstract
Telomeres, the protective ends of eukaryotic chromosomes, are replicated through concerted actions of conventional DNA polymerases and elongated by telomerase, but the regulation of this process is not fully understood. Telomere replication requires (Ctc1/Cdc13)‐Stn1‐Ten1, a telomeric ssDNA‐binding complex homologous to RPA. Here, we show that the evolutionarily conserved phosphatase Ssu72 is responsible for terminating the cycle of telomere replication in fission yeast. Ssu72 controls the recruitment of Stn1 to telomeres by regulating Stn1 phosphorylation at Ser74, a residue located within its conserved OB‐fold domain. Consequently, ssu72∆ mutants are defective in telomere replication and exhibit long 3′‐ssDNA overhangs, indicative of defective lagging‐strand DNA synthesis. We also show that hSSU72 regulates telomerase activation in human cells by controlling recruitment of hSTN1 to telomeres. These results reveal a previously unknown yet conserved role for the phosphatase SSU72, whereby this enzyme controls telomere homeostasis by activating lagging‐strand DNA synthesis, thus terminating the cycle of telomere replication.
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Affiliation(s)
| | | | | | - Clara C Reis
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Samah Matmati
- Equipe Labellisée Ligue, CRCM, CNRS, Inserm, Institut Paoli-Calmettes, Aix-Marseille University, Marseille, France
| | - Inês Matias Luís
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Isabel A Abreu
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Stéphane Coulon
- Equipe Labellisée Ligue, CRCM, CNRS, Inserm, Institut Paoli-Calmettes, Aix-Marseille University, Marseille, France
| | - Miguel Godinho Ferreira
- Instituto Gulbenkian de Ciência, Oeiras, Portugal .,Institute for Research on Cancer and Aging of Nice (IRCAN), INSERM U1081 UMR7284, CNRS, Nice, France
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52
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Macrophage achieves self-protection against oxidative stress-induced ageing through the Mst-Nrf2 axis. Nat Commun 2019; 10:755. [PMID: 30765703 PMCID: PMC6376064 DOI: 10.1038/s41467-019-08680-6] [Citation(s) in RCA: 149] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Accepted: 01/22/2019] [Indexed: 12/24/2022] Open
Abstract
Reactive oxygen species (ROS) production in phagocytes is a major defense mechanism against pathogens. However, the cellular self-protective mechanism against such potential damage from oxidative stress remains unclear. Here we show that the kinases Mst1 and Mst2 (Mst1/2) sense ROS and maintain cellular redox balance by modulating the stability of antioxidant transcription factor Nrf2. Site-specific ROS release recruits Mst1/2 from the cytosol to the phagosomal or mitochondrial membrane, with ROS subsequently activating Mst1/2 to phosphorylate kelch like ECH associated protein 1 (Keap1) and prevent Keap1 polymerization, thereby blocking Nrf2 ubiquitination and degradation to protect cells against oxidative damage. Treatment with the antioxidant N-acetylcysteine disrupts ROS-induced interaction of Mst1/2 with phagosomes or mitochondria, and thereby diminishes the Mst-Nrf2 signal. Consistently, loss of Mst1/2 results in increased oxidative injury, phagocyte ageing and death. Thus, our results identify the Mst-Nrf2 axis as an important ROS-sensing and antioxidant mechanism during an antimicrobial response. Immune cells produce reactive oxygen species (ROS) to eliminate pathogens, but cell-spontaneous death and ageing may also be induced. Here the authors show that, upon sensing ROS, Mst1/2 kinases modulate the activity of Nrf2 transcription factor and downstream genetic programs to protect mouse macrophages from death and ageing.
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53
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Coluzzi E, Leone S, Sgura A. Oxidative Stress Induces Telomere Dysfunction and Senescence by Replication Fork Arrest. Cells 2019; 8:cells8010019. [PMID: 30609792 PMCID: PMC6356380 DOI: 10.3390/cells8010019] [Citation(s) in RCA: 83] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Accepted: 12/29/2018] [Indexed: 12/12/2022] Open
Abstract
Oxidative DNA damage, particularly 8-oxoguanine, represents the most frequent DNA damage in human cells, especially at the telomeric level. The presence of oxidative lesions in the DNA can hinder the replication fork and is able to activate the DNA damage response. In this study, we wanted to understand the mechanisms by which oxidative damage causes telomere dysfunction and senescence in human primary fibroblasts. After acute oxidative stress at telomeres, our data demonstrated a reduction in TRF1 and TRF2, which are involved in proper telomere replication and T-loop formation, respectively. Furthermore, we observed a higher level of γH2AX with respect to 53BP1 at telomeres, suggesting a telomeric replication fork stall rather than double-strand breaks. To confirm this finding, we studied the replication of telomeres by Chromosome Orientation-FISH (CO-FISH). The data obtained show an increase in unreplicated telomeres after hydrogen peroxide treatment, corroborating the idea that the presence of 8-oxoG can induce replication fork arrest at telomeres. Lastly, we analyzed the H3K9me3 histone mark after oxidative stress at telomeres, and our results showed an increase of this marker, most likely inducing the heterochromatinization of telomeres. These results suggest that 8-oxoG is fundamental in oxidative stress-induced telomeric damage, principally causing replication fork arrest.
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Affiliation(s)
- Elisa Coluzzi
- Department of Science, University of Rome "Roma TRE", Viale Guglielmo Marconi, 446, 00146 Rome, Italy.
| | - Stefano Leone
- Department of Science, University of Rome "Roma TRE", Viale Guglielmo Marconi, 446, 00146 Rome, Italy.
| | - Antonella Sgura
- Department of Science, University of Rome "Roma TRE", Viale Guglielmo Marconi, 446, 00146 Rome, Italy.
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54
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Viviescas MA, Cano MIN, Segatto M. Chaperones and Their Role in Telomerase Ribonucleoprotein Biogenesis and Telomere Maintenance. CURR PROTEOMICS 2018. [DOI: 10.2174/1570164615666180713103133] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Telomere length maintenance is important for genome stability and cell division. In most
eukaryotes, telomeres are maintained by the telomerase ribonucleoprotein (RNP) complex, minimally
composed of the Telomerase Reverse Transcriptase (TERT) and the telomerase RNA (TER) components.
In addition to TERT and TER, other protein subunits are part of the complex and are involved in
telomerase regulation, assembly, disassembly, and degradation. Among them are some molecular
chaperones such as Hsp90 and its co-chaperone p23 which are found associated with the telomerase
RNP complex in humans, yeast and probably in protozoa. Hsp90 and p23 are necessary for the telomerase
RNP assembly and enzyme activity. In budding yeast, the Hsp90 homolog (Hsp82) is also responsible
for the association and dissociation of telomerase from the telomeric DNA by its direct interaction
with a telomere end-binding protein (Cdc13), responsible for regulating telomerase access to telomeres.
In addition, AAA+ ATPases, such as Pontin and Reptin, which are also considered chaperone-
like proteins, associate with the human telomerase complex by the direct interaction of Pontin with
TERT and dyskerin. They are probably responsible for telomerase RNP assembly since their depletion
impairs the accumulation of the complex. Moreover, various RNA chaperones, are also pivotal in the
assembly and migration of the mature telomerase complex and complex intermediates. In this review,
we will focus on the importance of molecular chaperones for telomerase RNP biogenesis and how they
impact telomere length maintenance and cellular homeostasis.
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Affiliation(s)
- Maria Alejandra Viviescas
- Genetics Department, Biosciences Institute, Sao Paulo State University (UNESP), Botucatu, SP, Brazil
| | | | - Marcela Segatto
- Genetics Department, Biosciences Institute, Sao Paulo State University (UNESP), Botucatu, SP, Brazil
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55
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Sargolzaeiaval F, Zhang J, Schleit J, Lessel D, Kubisch C, Precioso DR, Sillence D, Hisama FM, Dorschner M, Martin GM, Oshima J. CTC1 mutations in a Brazilian family with progeroid features and recurrent bone fractures. Mol Genet Genomic Med 2018; 6:1148-1156. [PMID: 30393977 PMCID: PMC6305643 DOI: 10.1002/mgg3.495] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 08/23/2018] [Accepted: 10/02/2018] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Cerebroretinal microangiopathy with calcifications and cysts (CRMCC) is an autosomal recessive disorder caused by pathogenic variants of the conserved telomere maintenance component 1 (CTC1) gene. The CTC1 forms the telomeric capping complex, CST, which functions in telomere homeostasis and replication. METHODS A Brazilian pedigree and an Australian pedigree were referred to the International Registry of Werner Syndrome (Seattle, WA, USA), with clinical features of accelerated aging and recurrent bone fractures. Whole exome sequencing was performed to identify the genetic causes. RESULTS Whole exome sequencing of the Brazilian pedigree revealed compound heterozygous pathogenic variants in CTC1: a missense mutation (c.2959C>T, p.Arg987Trp) and a novel stop codon change (c.322C>T, p.Arg108*). The Australian patient carried two novel heterozygous CTC1 variants, c.2916G>T, p.Val972Gly and c.2926G>T, p.Val976Phe within the same allele. Both heterozygous variants were inherited from the unaffected father, excluding the diagnosis of CRMCC in this pedigree. Cell biological studies demonstrated accumulation of double strand break foci in lymphoblastoid cell lines derived from the patients. Increased DSB foci were extended to non-telomeric regions of the genome, in agreement with previous biochemical studies showing a preferential binding of CTC1 protein to GC-rich sequences. CONCLUSION CTC1 pathogenic variants can present with unusual manifestations of progeria accompanied with recurrent bone fractures. Further studies are needed to elucidate the disease mechanism leading to the clinical presentation with intra-familial variations of CRMCC.
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Affiliation(s)
| | - Jiaming Zhang
- Department of Pathology, University of Washington, Seattle, Washington
| | - Jennifer Schleit
- Department of Pathology, University of Washington, Seattle, Washington
| | - Davor Lessel
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Christian Kubisch
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | | | - David Sillence
- Discipline of Genetic Medicine, Westmead Clinical School, Sydney Faculty of Medicine and Health, Westmead, Australia
| | - Fuki M Hisama
- Division of Medical Genetics, Department of Medicine, University of Washington, Seattle, Washington
| | - Michael Dorschner
- Department of Pathology, University of Washington, Seattle, Washington
| | - George M Martin
- Department of Pathology, University of Washington, Seattle, Washington
| | - Junko Oshima
- Department of Pathology, University of Washington, Seattle, Washington.,Department of Clinical Cell Biology and Medicine, Graduate School of Medicine, Chiba University, Chiba, Japan
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56
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Gu P, Jia S, Takasugi T, Smith E, Nandakumar J, Hendrickson E, Chang S. CTC1-STN1 coordinates G- and C-strand synthesis to regulate telomere length. Aging Cell 2018; 17:e12783. [PMID: 29774655 PMCID: PMC6052479 DOI: 10.1111/acel.12783] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/17/2018] [Indexed: 02/01/2023] Open
Abstract
Coats plus (CP) is a rare autosomal recessive disorder caused by mutations in CTC1, a component of the CST (CTC1, STN1, and TEN1) complex important for telomere length maintenance. The molecular basis of how CP mutations impact upon telomere length remains unclear. The CP CTC1L1142H mutation has been previously shown to disrupt telomere maintenance. In this study, we used CRISPR/Cas9 to engineer this mutation into both alleles of HCT116 and RPE cells to demonstrate that CTC1:STN1 interaction is required to repress telomerase activity. CTC1L1142H interacts poorly with STN1, leading to telomerase‐mediated telomere elongation. Impaired interaction between CTC1L1142H:STN1 and DNA Pol‐α results in increased telomerase recruitment to telomeres and further telomere elongation, revealing that C:S binding to DNA Pol‐α is required to fully repress telomerase activity. CP CTC1 mutants that fail to interact with DNA Pol‐α resulted in loss of C‐strand maintenance and catastrophic telomere shortening. Our findings place the CST complex as an important regulator of both G‐strand extensions by telomerase and C‐strand synthesis by DNA Pol‐α.
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Affiliation(s)
- Peili Gu
- Department of Laboratory Medicine; Yale University School of Medicine; New Haven Connecticut
| | - Shuting Jia
- Lab of Molecular Genetics of Aging and Tumor; Faculty of Medicine; Kunming University of Science and Technology; Kunming Yunnan Province China
| | - Taylor Takasugi
- Department of Laboratory Medicine; Yale University School of Medicine; New Haven Connecticut
- Department of Biochemistry, Molecular Biology and Biophysics; University of Minnesota Medical School; Minneapolis Minnesota
| | - Eric Smith
- Department of Molecular, Cellular, and Developmental Biology; University of Michigan; Ann Arbor Michigan
| | - Jayakrishnan Nandakumar
- Department of Molecular, Cellular, and Developmental Biology; University of Michigan; Ann Arbor Michigan
- Program in Chemical Biology; University of Michigan; Ann Arbor Michigan
| | - Eric Hendrickson
- Department of Biochemistry, Molecular Biology and Biophysics; University of Minnesota Medical School; Minneapolis Minnesota
| | - Sandy Chang
- Department of Laboratory Medicine; Yale University School of Medicine; New Haven Connecticut
- Department of Pathology; Yale University School of Medicine; New Haven Connecticut
- Molecular Biophysics and Biochemistry; Yale University School of Medicine; New Haven Connecticut
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57
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CTC1-STN1 terminates telomerase while STN1-TEN1 enables C-strand synthesis during telomere replication in colon cancer cells. Nat Commun 2018; 9:2827. [PMID: 30026550 PMCID: PMC6053418 DOI: 10.1038/s41467-018-05154-z] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Accepted: 06/07/2018] [Indexed: 01/20/2023] Open
Abstract
Telomerase elongates the telomeric G-strand to prevent telomere shortening through conventional DNA replication. However, synthesis of the complementary C-strand by DNA polymerase α is also required to maintain telomere length. Polymerase α cannot perform this role without the ssDNA binding complex CST (CTC1-STN1-TEN1). Here we describe the roles of individual CST subunits in telomerase regulation and G-overhang maturation in human colon cancer cells. We show that CTC1-STN1 limits telomerase action to prevent G-overhang overextension. CTC1-/- cells exhibit telomeric DNA damage and growth arrest due to overhang elongation whereas TEN1-/- cells do not. However, TEN1 is essential for C-strand synthesis and TEN1-/- cells exhibit progressive telomere shortening. DNA binding analysis indicates that CTC1-STN1 retains affinity for ssDNA but TEN1 stabilizes binding. We propose CTC1-STN1 binding is sufficient to terminate telomerase action but altered DNA binding dynamics renders CTC1-STN1 unable to properly engage polymerase α on the overhang for C-strand synthesis.
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58
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Mirman Z, Lottersberger F, Takai H, Kibe T, Gong Y, Takai K, Bianchi A, Zimmermann M, Durocher D, de Lange T. 53BP1-RIF1-shieldin counteracts DSB resection through CST- and Polα-dependent fill-in. Nature 2018; 560:112-116. [PMID: 30022158 PMCID: PMC6072559 DOI: 10.1038/s41586-018-0324-7] [Citation(s) in RCA: 272] [Impact Index Per Article: 45.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Accepted: 05/10/2018] [Indexed: 12/29/2022]
Abstract
Resection of double-strand breaks (DSBs) dictates the choice between Homology-Directed Repair (HDR), which requires a 3′ overhang, and classical Non-Homologous End Joining (c-NHEJ), which can join unresected ends1,2. BRCA1 mutant cancers show minimal DSB resection, rendering them HDR deficient and sensitive to PARP1 inhibitors (PARPi)3–8. When BRCA1 is absent, DSB resection is thought to be prevented by 53BP1, Rif1, and the Rev7/Shld1/Shld2/Shld3 (Shieldin) complex and loss of these factors diminishes PARPi sensitivity4,6–9. Here we address the mechanism by which 53BP1/Rif1/Shieldin regulate the generation of recombinogenic 3′ overhangs. We report that CST (Ctc1, Stn1, Ten110), an RPA-like complex that functions as a Polymeraseα/primase accessory factor11 is a downstream effector in the 53BP1 pathway. CST interacts with Shieldin and localizes with Polα to sites of DNA damage in a 53BP1- and Shieldin-dependent manner. Like loss of 53BP1/Rif1/Shieldin, CST depletion leads to increased resection. Furthermore, in BRCA1-deficient cells, CST blocks Rad51 loading and promotes PARPi efficacy. Finally, Polα inhibition diminishes the effect of PARPi in BRCA1-deficient cells. These data suggest that CST/Polα-mediated fill-in contributes to the control of DSB repair by 53BP1, Rif1, and Shieldin.
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Affiliation(s)
- Zachary Mirman
- Laboratory for Cell Biology and Genetics, Rockefeller University, New York, NY, USA
| | - Francisca Lottersberger
- Laboratory for Cell Biology and Genetics, Rockefeller University, New York, NY, USA.,Department of Medical and Health Sciences, Linköping University, Linköping, Sweden
| | - Hiroyuki Takai
- Laboratory for Cell Biology and Genetics, Rockefeller University, New York, NY, USA
| | - Tatsuya Kibe
- Laboratory for Cell Biology and Genetics, Rockefeller University, New York, NY, USA
| | - Yi Gong
- Laboratory for Cell Biology and Genetics, Rockefeller University, New York, NY, USA
| | - Kaori Takai
- Laboratory for Cell Biology and Genetics, Rockefeller University, New York, NY, USA
| | - Alessandro Bianchi
- Laboratory for Cell Biology and Genetics, Rockefeller University, New York, NY, USA.,Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, UK
| | - Michal Zimmermann
- Laboratory for Cell Biology and Genetics, Rockefeller University, New York, NY, USA.,Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Canada
| | - Daniel Durocher
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Canada
| | - Titia de Lange
- Laboratory for Cell Biology and Genetics, Rockefeller University, New York, NY, USA.
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59
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Armstrong CA, Tomita K. Fundamental mechanisms of telomerase action in yeasts and mammals: understanding telomeres and telomerase in cancer cells. Open Biol 2018; 7:rsob.160338. [PMID: 28330934 PMCID: PMC5376709 DOI: 10.1098/rsob.160338] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 02/20/2017] [Indexed: 12/12/2022] Open
Abstract
Aberrant activation of telomerase occurs in 85–90% of all cancers and underpins the ability of cancer cells to bypass their proliferative limit, rendering them immortal. The activity of telomerase is tightly controlled at multiple levels, from transcriptional regulation of the telomerase components to holoenzyme biogenesis and recruitment to the telomere, and finally activation and processivity. However, studies using cancer cell lines and other model systems have begun to reveal features of telomeres and telomerase that are unique to cancer. This review summarizes our current knowledge on the mechanisms of telomerase recruitment and activation using insights from studies in mammals and budding and fission yeasts. Finally, we discuss the differences in telomere homeostasis between normal cells and cancer cells, which may provide a foundation for telomere/telomerase targeted cancer treatments.
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Affiliation(s)
- Christine A Armstrong
- Chromosome Maintenance Group, UCL Cancer Institute, University College London, 72 Huntley Street, London WC1E 6DD, UK
| | - Kazunori Tomita
- Chromosome Maintenance Group, UCL Cancer Institute, University College London, 72 Huntley Street, London WC1E 6DD, UK
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60
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Barazas M, Annunziato S, Pettitt SJ, de Krijger I, Ghezraoui H, Roobol SJ, Lutz C, Frankum J, Song FF, Brough R, Evers B, Gogola E, Bhin J, van de Ven M, van Gent DC, Jacobs JJL, Chapman R, Lord CJ, Jonkers J, Rottenberg S. The CST Complex Mediates End Protection at Double-Strand Breaks and Promotes PARP Inhibitor Sensitivity in BRCA1-Deficient Cells. Cell Rep 2018; 23:2107-2118. [PMID: 29768208 PMCID: PMC5972230 DOI: 10.1016/j.celrep.2018.04.046] [Citation(s) in RCA: 93] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 03/24/2018] [Accepted: 04/11/2018] [Indexed: 12/29/2022] Open
Abstract
Selective elimination of BRCA1-deficient cells by inhibitors of poly(ADP-ribose) polymerase (PARP) is a prime example of the concept of synthetic lethality in cancer therapy. This interaction is counteracted by the restoration of BRCA1-independent homologous recombination through loss of factors such as 53BP1, RIF1, and REV7/MAD2L2, which inhibit end resection of DNA double-strand breaks (DSBs). To identify additional factors involved in this process, we performed CRISPR/SpCas9-based loss-of-function screens and selected for factors that confer PARP inhibitor (PARPi) resistance in BRCA1-deficient cells. Loss of members of the CTC1-STN1-TEN1 (CST) complex were found to cause PARPi resistance in BRCA1-deficient cells in vitro and in vivo. We show that CTC1 depletion results in the restoration of end resection and that the CST complex may act downstream of 53BP1/RIF1. These data suggest that, in addition to its role in protecting telomeres, the CST complex also contributes to protecting DSBs from end resection.
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Affiliation(s)
- Marco Barazas
- Division of Molecular Pathology, Oncode Institute, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands
| | - Stefano Annunziato
- Division of Molecular Pathology, Oncode Institute, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands
| | - Stephen J Pettitt
- The CRUK Gene Function Laboratory and Breast Cancer Now Toby Robins Research Centre, The Institute of Cancer Research, London SW3 6JB, UK
| | - Inge de Krijger
- Division of Oncogenomics, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands
| | - Hind Ghezraoui
- Genome Integrity Laboratory, Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Stefan J Roobol
- Department of Genetics, Erasmus University Medical Center, Rotterdam, the Netherlands; Department of Radiology and Nuclear Medicine, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Catrin Lutz
- Division of Molecular Pathology, Oncode Institute, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands
| | - Jessica Frankum
- The CRUK Gene Function Laboratory and Breast Cancer Now Toby Robins Research Centre, The Institute of Cancer Research, London SW3 6JB, UK
| | - Fei Fei Song
- The CRUK Gene Function Laboratory and Breast Cancer Now Toby Robins Research Centre, The Institute of Cancer Research, London SW3 6JB, UK
| | - Rachel Brough
- The CRUK Gene Function Laboratory and Breast Cancer Now Toby Robins Research Centre, The Institute of Cancer Research, London SW3 6JB, UK
| | - Bastiaan Evers
- Division of Molecular Carcinogenesis, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands
| | - Ewa Gogola
- Division of Molecular Pathology, Oncode Institute, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands
| | - Jinhyuk Bhin
- Division of Molecular Pathology, Oncode Institute, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands; Division of Molecular Carcinogenesis, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands
| | - Marieke van de Ven
- Division of Molecular Pathology, Oncode Institute, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands; Mouse Clinic for Cancer and Aging Research (MCCA), Preclinical Intervention Unit, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands
| | - Dik C van Gent
- Department of Genetics, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Jacqueline J L Jacobs
- Division of Oncogenomics, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands
| | - Ross Chapman
- Genome Integrity Laboratory, Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Christopher J Lord
- The CRUK Gene Function Laboratory and Breast Cancer Now Toby Robins Research Centre, The Institute of Cancer Research, London SW3 6JB, UK
| | - Jos Jonkers
- Division of Molecular Pathology, Oncode Institute, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands.
| | - Sven Rottenberg
- Division of Molecular Pathology, Oncode Institute, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands; Institute of Animal Pathology, Vetsuisse Faculty, University of Bern, Bern, Switzerland.
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61
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Matmati S, Vaurs M, Escandell JM, Maestroni L, Nakamura TM, Ferreira MG, Géli V, Coulon S. The fission yeast Stn1-Ten1 complex limits telomerase activity via its SUMO-interacting motif and promotes telomeres replication. SCIENCE ADVANCES 2018; 4:eaar2740. [PMID: 29774234 PMCID: PMC5955624 DOI: 10.1126/sciadv.aar2740] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 03/29/2018] [Indexed: 06/01/2023]
Abstract
Mammalian CST (CTC1-STN1-TEN1) complex fulfills numerous functions including rescue of the stalled replication forks and termination of telomerase action. In fission yeast lacking the CTC1 ortholog, the Stn1-Ten1 complex restricts telomerase action via its sumoylation-mediated interaction with Tpz1TPP1. We identify a small ubiquitin-like modifier (SUMO)-interacting motif (SIM) in the carboxyl-terminal part of Stn1 and show that this domain is crucial for SUMO and Tpz1-SUMO interactions. Point mutations in the SIM (Stn1-226) lead to telomere elongation, impair Stn1-Ten1 recruitment to telomeres, and enhance telomerase binding, revealing that Stn1 SIM domain contributes to the inhibition of telomerase activity at chromosome ends. Our results suggest that Stn1-Ten1 promotes DNA synthesis at telomeres to limit single-strand DNA accumulation. We further demonstrate that Stn1 functions in the replication of telomeric and subtelomeric regions in a Taz1-independent manner. Genetic analysis reveals that misregulation of origin firing and/or telomerase inhibition circumvents the replication defects of the stn1-226 mutant. Together, our results show that the Stn1-Ten1 complex has a dual function at telomeres by limiting telomerase action and promoting chromosome end replication.
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Affiliation(s)
- Samah Matmati
- CRCM, CNRS, INSERM, Aix-Marseille Université, Institut Paoli-Calmettes, Equipe Labellisée Ligue, 27 Boulevard Lei Roure, Marseille, France
| | - Mélina Vaurs
- CRCM, CNRS, INSERM, Aix-Marseille Université, Institut Paoli-Calmettes, Equipe Labellisée Ligue, 27 Boulevard Lei Roure, Marseille, France
| | - José M. Escandell
- Telomere and Genome Stability Laboratory, Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Laetitia Maestroni
- CRCM, CNRS, INSERM, Aix-Marseille Université, Institut Paoli-Calmettes, Equipe Labellisée Ligue, 27 Boulevard Lei Roure, Marseille, France
| | - Toru M. Nakamura
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Miguel G. Ferreira
- Telomere and Genome Stability Laboratory, Instituto Gulbenkian de Ciência, Oeiras, Portugal
- Institute for Research on Cancer and Aging, Nice, Faculty of Medicine, CNRS UMR7284, INSERM U1081, University of Nice Sophia Antipolis, Nice, France
| | - Vincent Géli
- CRCM, CNRS, INSERM, Aix-Marseille Université, Institut Paoli-Calmettes, Equipe Labellisée Ligue, 27 Boulevard Lei Roure, Marseille, France
| | - Stéphane Coulon
- CRCM, CNRS, INSERM, Aix-Marseille Université, Institut Paoli-Calmettes, Equipe Labellisée Ligue, 27 Boulevard Lei Roure, Marseille, France
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62
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Stewart JA, Wang Y, Ackerson SM, Schuck PL. Emerging roles of CST in maintaining genome stability and human disease. Front Biosci (Landmark Ed) 2018; 23:1564-1586. [PMID: 29293451 DOI: 10.2741/4661] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The human CTC1-STN1-TEN1 (CST) complex is a single-stranded DNA binding protein that shares homology with RPA and interacts with DNA polymerase alpha/primase. CST complexes are conserved from yeasts to humans and function in telomere maintenance. A common role of CST across species is in the regulation of telomere extension by telomerase and C-strand fill-in synthesis. However, recent studies also indicate that CST promotes telomere duplex replication as well the rescue of stalled DNA replication at non-telomeric sites. Furthermore, CST dysfunction and mutation is associated with several genetic diseases and cancers. In this review, we will summarize what is known about CST with a particular focus on the emerging roles of CST in DNA replication and human disease.
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Affiliation(s)
- Jason A Stewart
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA,
| | - Yilin Wang
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA
| | - Stephanie M Ackerson
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA
| | - Percy Logan Schuck
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA
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63
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Chastain M, Zhou Q, Shiva O, Fadri-Moskwik M, Whitmore L, Jia P, Dai X, Huang C, Ye P, Chai W. Human CST Facilitates Genome-wide RAD51 Recruitment to GC-Rich Repetitive Sequences in Response to Replication Stress. Cell Rep 2017; 16:1300-1314. [PMID: 27487043 DOI: 10.1016/j.celrep.2016.06.077] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Revised: 05/23/2016] [Accepted: 06/17/2016] [Indexed: 11/25/2022] Open
Abstract
The telomeric CTC1/STN1/TEN1 (CST) complex has been implicated in promoting replication recovery under replication stress at genomic regions, yet its precise role is unclear. Here, we report that STN1 is enriched at GC-rich repetitive sequences genome-wide in response to hydroxyurea (HU)-induced replication stress. STN1 deficiency exacerbates the fragility of these sequences under replication stress, resulting in chromosome fragmentation. We find that upon fork stalling, CST proteins form distinct nuclear foci that colocalize with RAD51. Furthermore, replication stress induces physical association of CST with RAD51 in an ATR-dependent manner. Strikingly, CST deficiency diminishes HU-induced RAD51 foci formation and reduces RAD51 recruitment to telomeres and non-telomeric GC-rich fragile sequences. Collectively, our findings establish that CST promotes RAD51 recruitment to GC-rich repetitive sequences in response to replication stress to facilitate replication restart, thereby providing insights into the mechanism underlying genome stability maintenance.
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Affiliation(s)
- Megan Chastain
- Department of Biomedical Sciences, Elson S. Floyd College of Medicine, Washington State University, Spokane, WA 99210, USA
| | - Qing Zhou
- Department of Biomedical Sciences, Elson S. Floyd College of Medicine, Washington State University, Spokane, WA 99210, USA
| | - Olga Shiva
- Department of Biomedical Sciences, Elson S. Floyd College of Medicine, Washington State University, Spokane, WA 99210, USA
| | - Maria Fadri-Moskwik
- Department of Biomedical Sciences, Elson S. Floyd College of Medicine, Washington State University, Spokane, WA 99210, USA
| | - Leanne Whitmore
- School of Molecular Biosciences, Washington State University, Pullman, WA 99164, USA
| | - Pingping Jia
- Department of Biomedical Sciences, Elson S. Floyd College of Medicine, Washington State University, Spokane, WA 99210, USA
| | - Xueyu Dai
- Department of Biomedical Sciences, Elson S. Floyd College of Medicine, Washington State University, Spokane, WA 99210, USA
| | - Chenhui Huang
- Department of Biomedical Sciences, Elson S. Floyd College of Medicine, Washington State University, Spokane, WA 99210, USA
| | - Ping Ye
- Department of Molecular and Experimental Medicine, Avera Cancer Institute, 1000 E 23rd Street, Suite 370, Sioux Falls, SD 57105, USA; Department of Pharmacy Practice, South Dakota State University, Brookings, SD 57007, USA
| | - Weihang Chai
- Department of Biomedical Sciences, Elson S. Floyd College of Medicine, Washington State University, Spokane, WA 99210, USA.
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64
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Lin H, Gong L, Zhan S, Wang Y, Liu A. Novel biallelic missense mutations in CTC1 gene identified in a Chinese family with Coats plus syndrome. J Neurol Sci 2017; 382:142-145. [DOI: 10.1016/j.jns.2017.09.041] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Revised: 09/26/2017] [Accepted: 09/27/2017] [Indexed: 01/01/2023]
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65
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Ganduri S, Lue NF. STN1-POLA2 interaction provides a basis for primase-pol α stimulation by human STN1. Nucleic Acids Res 2017; 45:9455-9466. [PMID: 28934486 PMCID: PMC5766158 DOI: 10.1093/nar/gkx621] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Accepted: 07/06/2017] [Indexed: 01/12/2023] Open
Abstract
The CST (CTC1–STN1–TEN1) complex mediates critical functions in maintaining telomere DNA and overcoming genome-wide replication stress. A conserved biochemical function of the CST complex is its primase-Pol α (PP) stimulatory activity. In this report, we demonstrate the ability of purified human STN1 alone to promote PP activity in vitro. We show that this regulation is mediated primarily by the N-terminal OB fold of STN1, but does not require the DNA-binding activity of this domain. Rather, we observed a strong correlation between the PP-stimulatory activity of STN1 variants and their abilities to bind POLA2. Remarkably, the main binding target of STN1 in POLA2 is the latter's central OB fold domain. In the substrate-free structure of PP, this domain is positioned so as to block nucleic acid entry to the Pol α active site. Thus the STN1–POLA2 interaction may promote the necessary conformational change for nucleic acid delivery to Pol α and subsequent DNA synthesis. A disease-causing mutation in human STN1 engenders a selective defect in POLA2-binding and PP stimulation, indicating that these activities are critical for the in vivo function of STN1. Our findings have implications for the molecular mechanisms of PP, STN1 and STN1-related molecular pathology.
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Affiliation(s)
- Swapna Ganduri
- Department of Microbiology & Immunology, W. R. Hearst Microbiology Research Center, Weill Cornell Medical College, New York, NY 10065, USA
| | - Neal F Lue
- Department of Microbiology & Immunology, W. R. Hearst Microbiology Research Center, Weill Cornell Medical College, New York, NY 10065, USA.,Sandra and Edward Meyer Cancer Center, Weill Cornell Medicine, New York, NY 10065, USA
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66
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Takikawa M, Tarumoto Y, Ishikawa F. Fission yeast Stn1 is crucial for semi-conservative replication at telomeres and subtelomeres. Nucleic Acids Res 2017; 45:1255-1269. [PMID: 28180297 PMCID: PMC5388396 DOI: 10.1093/nar/gkw1176] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2016] [Revised: 11/08/2016] [Accepted: 11/23/2016] [Indexed: 12/29/2022] Open
Abstract
The CST complex is a phylogenetically conserved protein complex consisting of CTC1/Cdc13, Stn1 and Ten1 that protects telomeres on linear chromosomes. Deletion of the fission yeast homologs stn1 and ten1 results in complete telomere loss; however, the precise function of Stn1 is still largely unknown. Here, we have isolated a high-temperature sensitive stn1 allele (termed stn1-1). stn1-1 cells abruptly lost telomeric sequence almost completely at the restrictive temperature. The loss of chromosomal DNA happened without gradual telomere shortening, and extended to 30 kb from the ends of chromosomes. We found transient and modest single-stranded G-strand exposure, but did not find any evidence of checkpoint activation in stn1-1 at the restrictive temperature. When we probed neutral-neutral 2D gels for subtelomere regions, we found no Y-arc-shaped replication intermediates in cycling cells. We conclude that the loss of telomere and subtelomere DNAs in stn1-1 cells at the restrictive temperature is caused by very frequent replication fork collapses specifically in subtelomere regions. Furthermore, we identified two independent suppressor mutants of the high-temperature sensitivity of stn1-1: a multi-copy form of pmt3 and a deletion of rif1. Collectively, we propose that fission yeast Stn1 primarily safeguards the semi-conservative DNA replication at telomeres and subtelomeres.
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Affiliation(s)
- Masahiro Takikawa
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto, Japan
| | - Yusuke Tarumoto
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto, Japan
| | - Fuyuki Ishikawa
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto, Japan
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67
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Feng X, Hsu SJ, Kasbek C, Chaiken M, Price CM. CTC1-mediated C-strand fill-in is an essential step in telomere length maintenance. Nucleic Acids Res 2017; 45:4281-4293. [PMID: 28334750 PMCID: PMC5416890 DOI: 10.1093/nar/gkx125] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Accepted: 02/15/2017] [Indexed: 11/13/2022] Open
Abstract
To prevent progressive telomere shortening as a result of conventional DNA replication, new telomeric DNA must be added onto the chromosome end. The de novo DNA synthesis involves elongation of the G-rich strand of the telomere by telomerase. In human cells, the CST complex (CTC1-STN1-TEN1) also functions in telomere replication. CST first aids in duplication of the telomeric dsDNA. Then after telomerase has extended the G-rich strand, CST facilitates fill-in synthesis of the complementary C-strand. Here, we analyze telomere structure after disruption of human CTC1 and demonstrate that functional CST is essential for telomere length maintenance due to its role in mediating C-strand fill-in. Removal of CTC1 results in elongation of the 3΄ overhang on the G-rich strand. This leads to accumulation of RPA and telomeric DNA damage signaling. G-overhang length increases with time after CTC1 disruption and at early times net G-strand growth is apparent, indicating telomerase-mediated G-strand extension. In contrast, C-strand length decreases continuously, indicating a deficiency in C-strand fill-in synthesis. The lack of C-strand maintenance leads to gradual shortening of the telomeric dsDNA, similar to that observed in cells lacking telomerase. Thus, telomerase-mediated G-strand extension and CST-mediated C-strand fill-in are equally important for telomere length maintenance.
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Affiliation(s)
- Xuyang Feng
- Department of Cancer Biology, University of Cincinnati, Cincinnati, OH 45230, USA
| | - Shih-Jui Hsu
- Department of Cancer Biology, University of Cincinnati, Cincinnati, OH 45230, USA
| | - Christopher Kasbek
- Department of Cancer Biology, University of Cincinnati, Cincinnati, OH 45230, USA
| | - Mary Chaiken
- Department of Cancer Biology, University of Cincinnati, Cincinnati, OH 45230, USA
| | - Carolyn M Price
- Department of Cancer Biology, University of Cincinnati, Cincinnati, OH 45230, USA
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68
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Hom RA, Wuttke DS. Human CST Prefers G-Rich but Not Necessarily Telomeric Sequences. Biochemistry 2017; 56:4210-4218. [PMID: 28726394 DOI: 10.1021/acs.biochem.7b00584] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The human CST (CTC1-STN1-TEN1) heterotrimeric complex plays roles in both telomere maintenance and DNA replication through its ability to interact with single-stranded DNA (ssDNA) of a variety of sequences. The precise sequence specificity required to execute these functions is unknown. Telomere-binding proteins have been shown to specifically recognize key telomeric sequence motifs within ssDNA while accommodating nonspecifically recognized sequences through conformationally plastic interfaces. To better understand the role CST plays in these processes, we have produced a highly purified heterotrimer and elucidated the sequence requirements for CST recognition of ssDNA in vitro. CST discriminates against random sequence and binds a minimal ssDNA comprised of three repeats of telomeric sequence. Replacement of individual nucleotides with their complement reveals that guanines are specifically recognized in a largely additive fashion and that specificity is distributed uniformly throughout the ligand. Unexpectedly, adenosines are also well tolerated at these sites, but cytosines are disfavored. Furthermore, sequences unrelated to the telomere repeat, yet still G-rich, bind CST well. Thus, CST is not inherently telomere-specific, but rather is a G-rich sequence binder. This biochemical activity is reminiscent of the yeast t-RPA and Tetrahymena thermophila CST complexes and is consistent with roles at G-rich sites throughout the genome.
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Affiliation(s)
- Robert A Hom
- Department of Chemistry and Biochemistry, UCB 596, University of Colorado , Boulder, Colorado 80309, United States
| | - Deborah S Wuttke
- Department of Chemistry and Biochemistry, UCB 596, University of Colorado , Boulder, Colorado 80309, United States
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69
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Gopalakrishnan V, Tan CR, Li S. Sequential phosphorylation of CST subunits by different cyclin-Cdk1 complexes orchestrate telomere replication. Cell Cycle 2017. [PMID: 28650257 DOI: 10.1080/15384101.2017.1312235] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
Telomeres are nucleoprotein structures that cap the ends of linear chromosomes. Telomere homeostasis is central to maintaining genomic integrity. In budding yeast, Cdk1 phosphorylates the telomere-specific binding protein, Cdc13, promoting the recruitment of telomerase to telomere and thereby telomere elongation. Cdc13 is also an integral part of the CST (Cdc13-Stn1-Ten1) complex that is essential for telomere capping and counteracting telomerase-dependent telomere elongation. Therefore, telomere length homeostasis is a balance between telomerase-extendable and CST-unextendable states. In our earlier work, we showed that Cdk1 also phosphorylates Stn1 which occurs sequentially following Cdc13 phosphorylation during cell cycle progression. This stabilizes the CST complex at the telomere and results in telomerase inhibition. Hence Cdk1-dependent phosphorylations of Stn1 acts like a molecular switch that drives Cdc13 to complex with Stn1-Ten1 rather than with telomerase. However, the underlying mechanism of how a single cyclin-dependent kinase phosphorylates Cdc13 and Stn1 in temporally distinct windows is largely unclear. Here, we show that S phase cyclins are necessary for telomere maintenance. The S phase and mitotic cyclins facilitate Cdc13 and Stn1 phosphorylation respectively, to exert opposing outcomes at the telomere. Thus, our results highlight a previously unappreciated role for cyclins in telomere replication.
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Affiliation(s)
| | - Cherylin Ruiling Tan
- b Department of Biological Sciences , National University of Singapore , Singapore
| | - Shang Li
- a Program in Cancer and Stem Cell Biology , Duke-NUS Medical School , Singapore.,c Department of Physiology , Yong Loo Lin School of Medicine, National University of Singapore , Singapore
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70
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Jahn A, Rane G, Paszkowski-Rogacz M, Sayols S, Bluhm A, Han CT, Draškovič I, Londoño-Vallejo JA, Kumar AP, Buchholz F, Butter F, Kappei D. ZBTB48 is both a vertebrate telomere-binding protein and a transcriptional activator. EMBO Rep 2017; 18:929-946. [PMID: 28500257 PMCID: PMC5452029 DOI: 10.15252/embr.201744095] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Revised: 03/31/2017] [Accepted: 04/18/2017] [Indexed: 11/09/2022] Open
Abstract
Telomeres constitute the ends of linear chromosomes and together with the shelterin complex form a structure essential for genome maintenance and stability. In addition to the constitutive binding of the shelterin complex, other direct, yet more transient interactions are mediated by the CST complex and HOT1/HMBOX1, while subtelomeric variant repeats are recognized by NR2C/F transcription factors. Recently, the Kruppel-like zinc finger protein ZBTB48/HKR3/TZAP has been described as a novel telomere-associated factor in the vertebrate lineage. Here, we show that ZBTB48 binds directly both to telomeric and to subtelomeric variant repeat sequences. ZBTB48 is found at telomeres of human cancer cells regardless of the mode of telomere maintenance and it acts as a negative regulator of telomere length. In addition to its telomeric function, we demonstrate through a combination of RNAseq, ChIPseq and expression proteomics experiments that ZBTB48 acts as a transcriptional activator on a small set of target genes, including mitochondrial fission process 1 (MTFP1). This discovery places ZBTB48 at the interface of telomere length regulation, transcriptional control and mitochondrial metabolism.
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Affiliation(s)
- Arne Jahn
- Medical Systems Biology, UCC, University Hospital and Medical Faculty Carl Gustav Carus, TU Dresden, Dresden, Germany.,Institute for Clinical Genetics, Medical Faculty Carl Gustav Carus, TU Dresden, Dresden, Germany
| | - Grishma Rane
- Cancer Science Institute of Singapore, National University of Singapore, Singapore City, Singapore
| | - Maciej Paszkowski-Rogacz
- Medical Systems Biology, UCC, University Hospital and Medical Faculty Carl Gustav Carus, TU Dresden, Dresden, Germany
| | - Sergi Sayols
- Institute of Molecular Biology (IMB) gGmbH, Mainz, Germany
| | - Alina Bluhm
- Institute of Molecular Biology (IMB) gGmbH, Mainz, Germany
| | - Chung-Ting Han
- Institute of Molecular Biology (IMB) gGmbH, Mainz, Germany
| | - Irena Draškovič
- Telomeres & Cancer Laboratory, UMR3244, Institut Curie-CNRS-UPMC, Paris Cedex 05, France
| | | | - Alan Prem Kumar
- Cancer Science Institute of Singapore, National University of Singapore, Singapore City, Singapore.,Department of Pharmacology, Yong Loo Lin School of Medicine National University of Singapore, Singapore City, Singapore.,Curtin Medical School, Faculty of Health Sciences Curtin University, Perth, Australia
| | - Frank Buchholz
- Medical Systems Biology, UCC, University Hospital and Medical Faculty Carl Gustav Carus, TU Dresden, Dresden, Germany .,Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany.,German Cancer Research Center (DKFZ), Heidelberg, Germany.,German Cancer Consortium (DKTK) Partner Site Dresden, Dresden, Germany.,National Center for Tumor Diseases (NCT), University Hospital Carl Gustav Carus, TU Dresden, Dresden, Germany
| | - Falk Butter
- Institute of Molecular Biology (IMB) gGmbH, Mainz, Germany
| | - Dennis Kappei
- Cancer Science Institute of Singapore, National University of Singapore, Singapore City, Singapore
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71
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Huang C, Jia P, Chastain M, Shiva O, Chai W. The human CTC1/STN1/TEN1 complex regulates telomere maintenance in ALT cancer cells. Exp Cell Res 2017; 355:95-104. [PMID: 28366536 DOI: 10.1016/j.yexcr.2017.03.058] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Revised: 03/27/2017] [Accepted: 03/28/2017] [Indexed: 11/24/2022]
Abstract
Maintaining functional telomeres is important for long-term proliferation of cells. About 15% of cancer cells are telomerase-negative and activate the alternative-lengthening of telomeres (ALT) pathway to maintain their telomeres. Recent studies have shown that the human CTC1/STN1/TEN1 complex (CST) plays a multi-faceted role in telomere maintenance in telomerase-expressing cancer cells. However, the role of CST in telomere maintenance in ALT cells is unclear. Here, we report that human CST forms a functional complex localizing in the ALT-associated PML bodies (APBs) in ALT cells throughout the cell cycle. Suppression of CST induces telomere instabilities including telomere fragility and elevates telomeric DNA recombination, leading to telomere dysfunction. In addition, CST deficiency significantly diminishes the abundance of extrachromosomal circular telomere DNA known as C-circles and t-circles. Suppression of CST also results in multinucleation in ALT cells and impairs cell proliferation. Our findings imply that the CST complex plays an important role in regulating telomere maintenance in ALT cells.
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Affiliation(s)
- Chenhui Huang
- Department of Biomedical Sciences, Elson S. Floyd College of Medicine, Washington State University, PO BOX 1495, Spokane, WA 99210, United States
| | - Pingping Jia
- Department of Biomedical Sciences, Elson S. Floyd College of Medicine, Washington State University, PO BOX 1495, Spokane, WA 99210, United States
| | - Megan Chastain
- Department of Biomedical Sciences, Elson S. Floyd College of Medicine, Washington State University, PO BOX 1495, Spokane, WA 99210, United States
| | - Olga Shiva
- Department of Biomedical Sciences, Elson S. Floyd College of Medicine, Washington State University, PO BOX 1495, Spokane, WA 99210, United States
| | - Weihang Chai
- Department of Biomedical Sciences, Elson S. Floyd College of Medicine, Washington State University, PO BOX 1495, Spokane, WA 99210, United States.
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72
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DNA Replication Origins and Fork Progression at Mammalian Telomeres. Genes (Basel) 2017; 8:genes8040112. [PMID: 28350373 PMCID: PMC5406859 DOI: 10.3390/genes8040112] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 03/23/2017] [Accepted: 03/24/2017] [Indexed: 12/20/2022] Open
Abstract
Telomeres are essential chromosomal regions that prevent critical shortening of linear chromosomes and genomic instability in eukaryotic cells. The bulk of telomeric DNA is replicated by semi-conservative DNA replication in the same way as the rest of the genome. However, recent findings revealed that replication of telomeric repeats is a potential cause of chromosomal instability, because DNA replication through telomeres is challenged by the repetitive telomeric sequences and specific structures that hamper the replication fork. In this review, we summarize current understanding of the mechanisms by which telomeres are faithfully and safely replicated in mammalian cells. Various telomere-associated proteins ensure efficient telomere replication at different steps, such as licensing of replication origins, passage of replication forks, proper fork restart after replication stress, and dissolution of post-replicative structures. In particular, shelterin proteins have central roles in the control of telomere replication. Through physical interactions, accessory proteins are recruited to maintain telomere integrity during DNA replication. Dormant replication origins and/or homology-directed repair may rescue inappropriate fork stalling or collapse that can cause defects in telomere structure and functions.
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73
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Adam S, Melguizo Sanchis D, El-Kamah G, Samarasinghe S, Alharthi S, Armstrong L, Lako M. Concise Review: Getting to the Core of Inherited Bone Marrow Failures. Stem Cells 2016; 35:284-298. [PMID: 27870251 PMCID: PMC5299470 DOI: 10.1002/stem.2543] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 10/15/2016] [Accepted: 10/28/2016] [Indexed: 12/20/2022]
Abstract
Bone marrow failure syndromes (BMFS) are a group of disorders with complex pathophysiology characterized by a common phenotype of peripheral cytopenia and/or hypoplastic bone marrow. Understanding genetic factors contributing to the pathophysiology of BMFS has enabled the identification of causative genes and development of diagnostic tests. To date more than 40 mutations in genes involved in maintenance of genomic stability, DNA repair, ribosome and telomere biology have been identified. In addition, pathophysiological studies have provided insights into several biological pathways leading to the characterization of genotype/phenotype correlations as well as the development of diagnostic approaches and management strategies. Recent developments in bone marrow transplant techniques and the choice of conditioning regimens have helped improve transplant outcomes. However, current morbidity and mortality remain unacceptable underlining the need for further research in this area. Studies in mice have largely been unable to mimic disease phenotype in humans due to difficulties in fully replicating the human mutations and the differences between mouse and human cells with regard to telomere length regulation, processing of reactive oxygen species and lifespan. Recent advances in induced pluripotency have provided novel insights into disease pathogenesis and have generated excellent platforms for identifying signaling pathways and functional mapping of haplo‐insufficient genes involved in large‐scale chromosomal deletions–associated disorders. In this review, we have summarized the current state of knowledge in the field of BMFS with specific focus on modeling the inherited forms and how to best utilize these models for the development of targeted therapies. Stem Cells2017;35:284–298
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Affiliation(s)
- Soheir Adam
- Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA.,Hematology Department, Medical School, King Abdulaziz University, Jeddah, KSA
| | | | - Ghada El-Kamah
- Division of Human Genetics & Genome Research, National Research Center, Cairo, Egypt
| | - Sujith Samarasinghe
- Department of Hematology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
| | - Sameer Alharthi
- Princess Al Jawhara Al-Brahim Center of Excellence in Research of Hereditary Disorders, King Abdulaziz University, KSA
| | - Lyle Armstrong
- Institute of Genetic Medicine, Newcastle University, United Kingdom
| | - Majlinda Lako
- Institute of Genetic Medicine, Newcastle University, United Kingdom
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74
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Li Y, Shen Y, Hohensinner P, Ju J, Wen Z, Goodman SB, Zhang H, Goronzy JJ, Weyand CM. Deficient Activity of the Nuclease MRE11A Induces T Cell Aging and Promotes Arthritogenic Effector Functions in Patients with Rheumatoid Arthritis. Immunity 2016; 45:903-916. [PMID: 27742546 DOI: 10.1016/j.immuni.2016.09.013] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Revised: 07/01/2016] [Accepted: 08/11/2016] [Indexed: 01/08/2023]
Abstract
Immune aging manifests with a combination of failing adaptive immunity and insufficiently restrained inflammation. In patients with rheumatoid arthritis (RA), T cell aging occurs prematurely, but the mechanisms involved and their contribution to tissue-destructive inflammation remain unclear. We found that RA CD4+ T cells showed signs of aging during their primary immune responses and differentiated into tissue-invasive, proinflammatory effector cells. RA T cells had low expression of the double-strand-break repair nuclease MRE11A, leading to telomeric damage, juxtacentromeric heterochromatin unraveling, and senescence marker upregulation. Inhibition of MRE11A activity in healthy T cells induced the aging phenotype, whereas MRE11A overexpression in RA T cells reversed it. In human-synovium chimeric mice, MRE11Alow T cells were tissue-invasive and pro-arthritogenic, and MRE11A reconstitution mitigated synovitis. Our findings link premature T cell aging and tissue-invasiveness to telomere deprotection and heterochromatin unpacking, identifying MRE11A as a therapeutic target to combat immune aging and suppress dysregulated tissue inflammation.
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Affiliation(s)
- Yinyin Li
- Division of Immunology and Rheumatology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Yi Shen
- Division of Immunology and Rheumatology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Philipp Hohensinner
- Division of Immunology and Rheumatology, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Internal Medicine II/Cardiology, Medical University of Vienna, 1090 Vienna, Austria
| | - Jihang Ju
- Division of Immunology and Rheumatology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Zhenke Wen
- Division of Immunology and Rheumatology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Stuart B Goodman
- Department of Orthopedic Surgery and Bioengineering, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Hui Zhang
- Division of Immunology and Rheumatology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Jörg J Goronzy
- Division of Immunology and Rheumatology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Cornelia M Weyand
- Division of Immunology and Rheumatology, Stanford University School of Medicine, Stanford, CA 94305, USA.
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Lloyd NR, Dickey TH, Hom RA, Wuttke DS. Tying up the Ends: Plasticity in the Recognition of Single-Stranded DNA at Telomeres. Biochemistry 2016; 55:5326-40. [PMID: 27575340 PMCID: PMC5656232 DOI: 10.1021/acs.biochem.6b00496] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Telomeres terminate nearly exclusively in single-stranded DNA (ssDNA) overhangs comprised of the G-rich 3' end. This overhang varies widely in length from species to species, ranging from just a few bases to several hundred nucleotides. These overhangs are not merely a remnant of DNA replication but rather are the result of complex further processing. Proper management of the telomeric overhang is required both to deter the action of the DNA damage machinery and to present the ends properly to the replicative enzyme telomerase. This Current Topic addresses the biochemical and structural features used by the proteins that manage these variable telomeric overhangs. The Pot1 protein tightly binds the single-stranded overhang, preventing DNA damage sensors from binding. Pot1 also orchestrates the access of telomerase to that same substrate. The remarkable plasticity of the binding interface exhibited by the Schizosaccharomyces pombe Pot1 provides mechanistic insight into how these roles may be accomplished, and disease-associated mutations clustered around the DNA-binding interface in the hPOT1 highlight the importance of this function. The budding yeast Cdc13-Stn1-Ten1, a telomeric RPA complex closely associated with telomere function, also interacts with ssDNA in a fashion that allows degenerate sequences to be recognized. A related human complex composed of hCTC1, hSTN1, and hTEN1 has recently emerged with links to both telomere maintenance and general DNA replication and also exhibits mutations associated with telomere pathologies. Overall, these sequence-specific ssDNA binders exhibit a range of recognition properties that allow them to perform their unique biological functions.
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Affiliation(s)
- Neil R. Lloyd
- Department of Chemistry and Biochemistry, 596 UCB, University of Colorado Boulder, Boulder, CO 80309-0596, USADepartment of Chemistry and Biochemistry, 596 UCB, University of Colorado Boulder, Boulder, CO 80309, USA
| | | | - Robert A. Hom
- Department of Chemistry and Biochemistry, 596 UCB, University of Colorado Boulder, Boulder, CO 80309-0596, USADepartment of Chemistry and Biochemistry, 596 UCB, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Deborah S. Wuttke
- Department of Chemistry and Biochemistry, 596 UCB, University of Colorado Boulder, Boulder, CO 80309-0596, USADepartment of Chemistry and Biochemistry, 596 UCB, University of Colorado Boulder, Boulder, CO 80309, USA
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76
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Majerská J, Redon S, Lingner J. Quantitative telomeric chromatin isolation protocol for human cells. Methods 2016; 114:28-38. [PMID: 27520492 DOI: 10.1016/j.ymeth.2016.08.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 07/19/2016] [Accepted: 08/07/2016] [Indexed: 12/19/2022] Open
Abstract
The ends of eukaryotic chromosomes, known as telomeres, consist of repetitive DNA sequences, multiple proteins and noncoding RNAs. Telomeres are dynamic structures that play crucial roles as guardians of genome stability and tumor suppressors. Defects in telomere length or protein composition can accelerate aging and are seen in telomere syndromes, which affect various proliferative tissues such as the bone marrow or the lungs. One of the biggest challenges in the telomere field is to identify the molecular changes at telomeres that occur during normal development, in cancer and in telomere syndromes. To tackle this problem, our laboratory has established a quantitative telomeric chromatin isolation protocol (QTIP) for human cells, in which chromatin is cross-linked, immunopurified and analyzed by mass spectrometry. QTIP involves stable isotope labeling by amino acids in cell culture (SILAC) to compare and identify quantitative differences in telomere protein composition of cells from various states.
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Affiliation(s)
- Jana Majerská
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Sophie Redon
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Joachim Lingner
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
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Simon AJ, Lev A, Zhang Y, Weiss B, Rylova A, Eyal E, Kol N, Barel O, Cesarkas K, Soudack M, Greenberg-Kushnir N, Rhodes M, Wiest DL, Schiby G, Barshack I, Katz S, Pras E, Poran H, Reznik-Wolf H, Ribakovsky E, Simon C, Hazou W, Sidi Y, Lahad A, Katzir H, Sagie S, Aqeilan HA, Glousker G, Amariglio N, Tzfati Y, Selig S, Rechavi G, Somech R. Mutations in STN1 cause Coats plus syndrome and are associated with genomic and telomere defects. J Exp Med 2016; 213:1429-40. [PMID: 27432940 PMCID: PMC4986528 DOI: 10.1084/jem.20151618] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2015] [Accepted: 06/10/2016] [Indexed: 12/18/2022] Open
Abstract
The analysis of individuals with telomere defects may shed light on the delicate interplay of factors controlling genome stability, premature aging, and cancer. We herein describe two Coats plus patients with telomere and genomic defects; both harbor distinct, novel mutations in STN1, a member of the human CTC1-STN1-TEN1 (CST) complex, thus linking this gene for the first time to a human telomeropathy. We characterized the patients' phenotype, recapitulated it in a zebrafish model and rescued cellular and clinical aspects by the ectopic expression of wild-type STN1 or by thalidomide treatment. Interestingly, a significant lengthy control of the gastrointestinal bleeding in one of our patients was achieved by thalidomide treatment, exemplifying a successful bed-to-bench-and-back approach.
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Affiliation(s)
- Amos J Simon
- Pediatric Department A and Immunology Service, Jeffrey Modell Foundation Center, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Tel Hashomer, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel Division of Haematology and Bone Marrow Transplantation, Sheba Medical Center, Tel Hashomer, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel The Wohl Institute for Translational Medicine, Sheba Medical Center, Tel Hashomer, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Atar Lev
- Pediatric Department A and Immunology Service, Jeffrey Modell Foundation Center, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Tel Hashomer, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel The Wohl Institute for Translational Medicine, Sheba Medical Center, Tel Hashomer, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Yong Zhang
- Blood Cell Development and Function Program, Fox Chase Cancer Center, Philadelphia, PA 19111
| | - Batia Weiss
- The Wohl Institute for Translational Medicine, Sheba Medical Center, Tel Hashomer, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel Pediatric Gastroenterology and Nutrition Unit, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Tel Hashomer, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Anna Rylova
- Pediatric Department A and Immunology Service, Jeffrey Modell Foundation Center, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Tel Hashomer, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Eran Eyal
- The Wohl Institute for Translational Medicine, Sheba Medical Center, Tel Hashomer, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel Sheba Cancer Research Center, Sheba Medical Center, Tel Hashomer, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Nitzan Kol
- The Wohl Institute for Translational Medicine, Sheba Medical Center, Tel Hashomer, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel Sheba Cancer Research Center, Sheba Medical Center, Tel Hashomer, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Ortal Barel
- The Wohl Institute for Translational Medicine, Sheba Medical Center, Tel Hashomer, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel Sheba Cancer Research Center, Sheba Medical Center, Tel Hashomer, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Keren Cesarkas
- The Wohl Institute for Translational Medicine, Sheba Medical Center, Tel Hashomer, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel Sheba Cancer Research Center, Sheba Medical Center, Tel Hashomer, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Michalle Soudack
- Imaging Unit, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Tel Hashomer, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Noa Greenberg-Kushnir
- Blood Cell Development and Function Program, Fox Chase Cancer Center, Philadelphia, PA 19111
| | - Michele Rhodes
- Blood Cell Development and Function Program, Fox Chase Cancer Center, Philadelphia, PA 19111
| | - David L Wiest
- Blood Cell Development and Function Program, Fox Chase Cancer Center, Philadelphia, PA 19111
| | - Ginette Schiby
- The Wohl Institute for Translational Medicine, Sheba Medical Center, Tel Hashomer, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel Department of Pathology, Sheba Medical Center, Tel Hashomer, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Iris Barshack
- Department of Pathology, Sheba Medical Center, Tel Hashomer, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Shulamit Katz
- Pediatric Department A and Immunology Service, Jeffrey Modell Foundation Center, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Tel Hashomer, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Elon Pras
- The Danek Gertner Institute of Human Genetics, Sheba Medical Center, Tel Hashomer, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Hana Poran
- The Danek Gertner Institute of Human Genetics, Sheba Medical Center, Tel Hashomer, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Haike Reznik-Wolf
- The Danek Gertner Institute of Human Genetics, Sheba Medical Center, Tel Hashomer, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Elena Ribakovsky
- Division of Haematology and Bone Marrow Transplantation, Sheba Medical Center, Tel Hashomer, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Carlos Simon
- Division of Gastroenterology, Sheba Medical Center, Tel Hashomer, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Wadi Hazou
- Department of Internal Medicine C, Sheba Medical Center, Tel Hashomer, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Yechezkel Sidi
- Department of Internal Medicine C, Sheba Medical Center, Tel Hashomer, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Avishay Lahad
- Pediatric Gastroenterology and Nutrition Unit, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Tel Hashomer, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Hagar Katzir
- Laboratory of Molecular Medicine, Rambam Health Care Campus and Rappaport Faculty of Medicine and Research Institute, Technion, Haifa 8875361, Israel
| | - Shira Sagie
- Laboratory of Molecular Medicine, Rambam Health Care Campus and Rappaport Faculty of Medicine and Research Institute, Technion, Haifa 8875361, Israel
| | - Haifa A Aqeilan
- Department of Genetics, The Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Edmond Safra Campus, Givat Ram, Jerusalem 9190401, Israel
| | - Galina Glousker
- Department of Genetics, The Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Edmond Safra Campus, Givat Ram, Jerusalem 9190401, Israel
| | - Ninette Amariglio
- Division of Haematology and Bone Marrow Transplantation, Sheba Medical Center, Tel Hashomer, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel The Wohl Institute for Translational Medicine, Sheba Medical Center, Tel Hashomer, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel Sheba Cancer Research Center, Sheba Medical Center, Tel Hashomer, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel The Everard and Mina Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan 5290002, Israel
| | - Yehuda Tzfati
- Department of Genetics, The Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Edmond Safra Campus, Givat Ram, Jerusalem 9190401, Israel
| | - Sara Selig
- Laboratory of Molecular Medicine, Rambam Health Care Campus and Rappaport Faculty of Medicine and Research Institute, Technion, Haifa 8875361, Israel
| | - Gideon Rechavi
- The Wohl Institute for Translational Medicine, Sheba Medical Center, Tel Hashomer, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel Sheba Cancer Research Center, Sheba Medical Center, Tel Hashomer, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Raz Somech
- Pediatric Department A and Immunology Service, Jeffrey Modell Foundation Center, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Tel Hashomer, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel The Wohl Institute for Translational Medicine, Sheba Medical Center, Tel Hashomer, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
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78
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Zhou Q, Chai W. Suppression of STN1 enhances the cytotoxicity of chemotherapeutic agents in cancer cells by elevating DNA damage. Oncol Lett 2016; 12:800-808. [PMID: 27446354 PMCID: PMC4950739 DOI: 10.3892/ol.2016.4676] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2015] [Accepted: 04/22/2016] [Indexed: 11/06/2022] Open
Abstract
DNA damage-inducing agents are among the most effective treatment regimens in clinical chemotherapy. However, drug resistance and severe side effects caused by these agents greatly limit their efficacy. Sensitizing malignant cells to chemotherapeutic agents has long been a goal of chemotherapy. In the present study, suppression of STN1, a gene important for safeguarding genome stability, potentiated the anticancer effect of chemotherapeutic agents in tumor cells. Using multiple cancer cells from a variety of origins, it was observed that downregulation of STN1 resulted in a significant decrease in the half maximal inhibitory concentration values of several conventional anticancer agents. When cells are treated with anticancer agents, STN1 suppression leads to a decline in colony formation and diminished anchorage-independent growth. Furthermore, it was additionally observed that STN1 knockdown augmented the levels of DNA damage caused by damage-inducing agents. The present study concluded that suppression of STN1 enhances the cytotoxicity of damage-inducing chemotherapeutic agents by increasing DNA damage in cancer cells.
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Affiliation(s)
- Qing Zhou
- Department of Biomedical Sciences, Elson S. Floyd College of Medical Sciences, Washington State University, Spokane, WA 99210, USA
| | - Weihang Chai
- Department of Biomedical Sciences, Elson S. Floyd College of Medical Sciences, Washington State University, Spokane, WA 99210, USA; School of Molecular Biosciences, Washington State University, Spokane, WA 99210, USA
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79
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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: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [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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80
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Rice C, Skordalakes E. Structure and function of the telomeric CST complex. Comput Struct Biotechnol J 2016; 14:161-7. [PMID: 27239262 PMCID: PMC4872678 DOI: 10.1016/j.csbj.2016.04.002] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 04/06/2016] [Accepted: 04/07/2016] [Indexed: 11/25/2022] Open
Abstract
Telomeres comprise the ends of eukaryotic chromosomes and are essential for cell proliferation and genome maintenance. Telomeres are replicated by telomerase, a ribonucleoprotein (RNP) reverse transcriptase, and are maintained primarily by nucleoprotein complexes such as shelterin (TRF1, TRF2, TIN2, RAP1, POT1, TPP1) and CST (Cdc13/Ctc1, Stn1, Ten1). The focus of this review is on the CST complex and its role in telomere maintenance. Although initially thought to be unique to yeast, it is now evident that the CST complex is present in a diverse range of organisms where it contributes to genome maintenance. The CST accomplishes these tasks via telomere capping and by regulating telomerase and DNA polymerase alpha-primase (polα-primase) access to telomeres, a process closely coordinated with the shelterin complex in most organisms. The goal of this review is to provide a brief but comprehensive account of the diverse, and in some cases organism-dependent, functions of the CST complex and how it contributes to telomere maintenance and cell proliferation.
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81
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Takai H, Jenkinson E, Kabir S, Babul-Hirji R, Najm-Tehrani N, Chitayat DA, Crow YJ, de Lange T. A POT1 mutation implicates defective telomere end fill-in and telomere truncations in Coats plus. Genes Dev 2016; 30:812-26. [PMID: 27013236 PMCID: PMC4826397 DOI: 10.1101/gad.276873.115] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Accepted: 03/02/2016] [Indexed: 11/24/2022]
Abstract
Coats plus (CP) can be caused by mutations in the CTC1 component of CST, which promotes polymerase α (polα)/primase-dependent fill-in throughout the genome and at telomeres. The cellular pathology relating to CP has not been established. We identified a homozygous POT1 S322L substitution (POT1(CP)) in two siblings with CP. POT1(CP)induced a proliferative arrest that could be bypassed by telomerase. POT1(CP)was expressed at normal levels, bound TPP1 and telomeres, and blocked ATR signaling. POT1(CP)was defective in regulating telomerase, leading to telomere elongation rather than the telomere shortening observed in other telomeropathies. POT1(CP)was also defective in the maintenance of the telomeric C strand, causing extended 3' overhangs and stochastic telomere truncations that could be healed by telomerase. Consistent with shortening of the telomeric C strand, metaphase chromosomes showed loss of telomeres synthesized by leading strand DNA synthesis. We propose that CP is caused by a defect in POT1/CST-dependent telomere fill-in. We further propose that deficiency in the fill-in step generates truncated telomeres that halt proliferation in cells lacking telomerase, whereas, in tissues expressing telomerase (e.g., bone marrow), the truncations are healed. The proposed etiology can explain why CP presents with features distinct from those associated with telomerase defects (e.g., dyskeratosis congenita).
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Affiliation(s)
- Hiroyuki Takai
- The Rockefeller University, New York, New York 10065, USA
| | - Emma Jenkinson
- Manchester Centre for Genomic Medicine, Institute of Human Development, Faculty of Medical and Human Sciences, Manchester Academic Health Sciences Centre, University of Manchester, Manchester M13 9PT, United Kingdom
| | - Shaheen Kabir
- The Rockefeller University, New York, New York 10065, USA
| | - Riyana Babul-Hirji
- Department of Pediatrics, Division of Clinical and Metabolic Genetics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario M5G 1Z5, Canada
| | - Nasrin Najm-Tehrani
- Department of Pediatrics, Division of Opthalmology and Visions Sciences, The Hospital for Sick Children, University of Toronto, Toronto, Ontario M5G 1Z5, Canada
| | - David A Chitayat
- The Prenatal Diagnosis and Medical Genetics Program, Department of Obstetrics and Gynecology, Mount Sinai Hospital, University of Toronto, Toronto, Ontario M5G 1X5, Canada; Department of Paediatrics, Division of Clinical and Metabolic Genetics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario M5G 1Z5, Canada
| | - Yanick J Crow
- Manchester Centre for Genomic Medicine, Institute of Human Development, Faculty of Medical and Human Sciences, Manchester Academic Health Sciences Centre, University of Manchester, Manchester M13 9PT, United Kingdom; UMR 1163, Institut National de la Santé et de la Recherche Médicale, Laboratory of Neurogenetics and Neuroinflammation, Paris Descartes-Sorbonne Paris Cité University, Institut Imagine, Hôpital Necker, Paris 75015, France
| | - Titia de Lange
- The Rockefeller University, New York, New York 10065, USA
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82
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Shen H, McHale CM, Haider SI, Jung C, Zhang S, Smith MT, Zhang L. Identification of Genes That Modulate Susceptibility to Formaldehyde and Imatinib by Functional Genomic Screening in Human Haploid KBM7 Cells. Toxicol Sci 2016; 151:10-22. [PMID: 27008852 DOI: 10.1093/toxsci/kfw032] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Though current functional genomic screening systems are useful for investigating human susceptibility to chemical toxicity, they have limitations. Well-established, high-throughput yeast mutant screens identify only evolutionarily conserved processes. RNA interference can be applied in human cells but is limited by incomplete gene knockout and off-target effects. Human haploid cell screening is advantageous as it requires knockdown of only a single copy of each gene. A human haploid cell mutant library (KBM7-Mu), derived from a chronic myeloid leukemia (CML) patient, was recently developed and has been used to identify genes that modulate sensitivity to infectious agents and pharmaceutical drugs. Here, we sought to improve the KBM7-Mu screening process to enable efficient screening of environmental chemicals. We developed a semi-solid medium based screening approach that cultures individual mutant colonies from chemically resistant cells, faster (by 2-3 weeks) and with less labor than the original liquid medium-based approach. As proof of principle, we identified genetic mutants that confer resistance to the carcinogen formaldehyde (FA, 12 genes, 18 hits) and the CML chemotherapeutic agent imatinib (6 genes, 13 hits). Validation experiments conducted on KBM7 mutants lacking each of the 18 genes confirmed resistance of 6 FA mutants (CTC1, FCRLA, GOT1, LPR5, M1AP, and MAP2K5) and 1 imatinib-resistant mutant (LYRM9). Despite the improvements to the method, it remains technically challenging to limit false positive findings. Nonetheless, our findings demonstrate the broad applicability of this optimized haploid approach to screen toxic chemicals to identify novel susceptibility genes and gain insight into potential mechanisms of toxicity.
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Affiliation(s)
- Hua Shen
- Superfund Research Program, School of Public Health, University of California, Berkeley, California 94720
| | - Cliona M McHale
- Superfund Research Program, School of Public Health, University of California, Berkeley, California 94720
| | - Syed I Haider
- Superfund Research Program, School of Public Health, University of California, Berkeley, California 94720
| | - Cham Jung
- Superfund Research Program, School of Public Health, University of California, Berkeley, California 94720
| | - Susie Zhang
- Superfund Research Program, School of Public Health, University of California, Berkeley, California 94720
| | - Martyn T Smith
- Superfund Research Program, School of Public Health, University of California, Berkeley, California 94720
| | - Luoping Zhang
- Superfund Research Program, School of Public Health, University of California, Berkeley, California 94720
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83
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Wang F, Stewart J, Price CM. Human CST abundance determines recovery from diverse forms of DNA damage and replication stress. Cell Cycle 2015; 13:3488-98. [PMID: 25483097 DOI: 10.4161/15384101.2014.964100] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Mammalian CST (CTC1-STN1-TEN1) is a telomere-associated complex that functions in telomere duplex replication and fill-in synthesis of the telomeric C-strand following telomerase action. CST also facilitates genome-wide replication recovery after HU-induced fork stalling by increasing origin firing. CTC1 and STN1 were originally isolated as a DNA polymerase α stimulatory factor. Here we explore how CST abundance affects recovery from drugs that cause different types of DNA damage and replication stress. We show that recovery from HU and aphidicolin induced replication stress is increased by CST over-expression. Elevated CST increases dNTP incorporation and origin firing after HU release and decreases the incidence of anaphase bridges and micronuclei after aphidicolin removal. While the frequency of origin firing after HU release is proportional to CST abundance, the number of cells entering S-phase to initiate replication is unchanged by CST overexpression or STN1 depletion. Instead the CST-related changes in origin firing take place in cells that were already in S-phase at the time of HU addition, indicating that CST modulates firing of late or dormant origins. CST abundance also influences cell viability after treatment with HU, aphidicolin, MMS and camptothecin. Viability is increased by elevated CST and decreased by STN1 depletion, indicating that endogenous CST levels are limiting. However, CST abundance does not affect viability after MMC treatment. Thus, CST facilitates recovery from many, but not all, forms of exogenous DNA damage. Overall our results suggest that CST is needed in stoichiometric amounts to facilitate re-initiation of DNA replication at repaired forks and/or dormant origins.
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Affiliation(s)
- Feng Wang
- a Department of Cancer Biology ; University of Cincinnati ; Cincinnati , OH USA
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84
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Martínez P, Blasco MA. Replicating through telomeres: a means to an end. Trends Biochem Sci 2015; 40:504-15. [PMID: 26188776 DOI: 10.1016/j.tibs.2015.06.003] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Revised: 06/08/2015] [Accepted: 06/12/2015] [Indexed: 02/07/2023]
Abstract
Proper replication of the telomeric DNA at chromosome ends is critical for preserving genome integrity. Yet, telomeres present challenges for the replication machinery, such as their repetitive and heterochromatic nature and their potential to form non-Watson-Crick structures as well as the fact that they are transcribed. Numerous telomere-bound proteins are required to facilitate progression of the replication fork throughout telomeric DNA. In particular, shelterin plays crucial functions in telomere length regulation, protection of telomeres from nuclease degradation, control of DNA damage response at telomeres, and the recruitment of associated factors required for telomere DNA processing and replication. In this review we discuss the recently uncovered functions of mammalian telomere-specific and telomere-associated proteins that facilitate proper telomere replication.
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Affiliation(s)
- Paula Martínez
- Telomeres and Telomerase Group, Molecular Oncology Program, Spanish National Cancer Research Centre (CNIO), Madrid E-28029, Spain
| | - Maria A Blasco
- Telomeres and Telomerase Group, Molecular Oncology Program, Spanish National Cancer Research Centre (CNIO), Madrid E-28029, Spain.
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85
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Burla R, Carcuro M, Raffa GD, Galati A, Raimondo D, Rizzo A, La Torre M, Micheli E, Ciapponi L, Cenci G, Cundari E, Musio A, Biroccio A, Cacchione S, Gatti M, Saggio I. AKTIP/Ft1, a New Shelterin-Interacting Factor Required for Telomere Maintenance. PLoS Genet 2015; 11:e1005167. [PMID: 26110528 PMCID: PMC4481533 DOI: 10.1371/journal.pgen.1005167] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 03/23/2015] [Indexed: 12/18/2022] Open
Abstract
Telomeres are nucleoprotein complexes that protect the ends of linear chromosomes from incomplete replication, degradation and detection as DNA breaks. Mammalian telomeres are protected by shelterin, a multiprotein complex that binds the TTAGGG telomeric repeats and recruits a series of additional factors that are essential for telomere function. Although many shelterin-associated proteins have been so far identified, the inventory of shelterin-interacting factors required for telomere maintenance is still largely incomplete. Here, we characterize AKTIP/Ft1 (human AKTIP and mouse Ft1 are orthologous), a novel mammalian shelterin-bound factor identified on the basis of its homology with the Drosophila telomere protein Pendolino. AKTIP/Ft1 shares homology with the E2 variant ubiquitin-conjugating (UEV) enzymes and has been previously implicated in the control of apoptosis and in vesicle trafficking. RNAi-mediated depletion of AKTIP results in formation of telomere dysfunction foci (TIFs). Consistent with these results, AKTIP interacts with telomeric DNA and binds the shelterin components TRF1 and TRF2 both in vivo and in vitro. Analysis of AKTIP- depleted human primary fibroblasts showed that they are defective in PCNA recruiting and arrest in the S phase due to the activation of the intra S checkpoint. Accordingly, AKTIP physically interacts with PCNA and the RPA70 DNA replication factor. Ft1-depleted p53-/- MEFs did not arrest in the S phase but displayed significant increases in multiple telomeric signals (MTS) and sister telomere associations (STAs), two hallmarks of defective telomere replication. In addition, we found an epistatic relation for MST formation between Ft1 and TRF1, which has been previously shown to be required for replication fork progression through telomeric DNA. Ch-IP experiments further suggested that in AKTIP-depleted cells undergoing the S phase, TRF1 is less tightly bound to telomeric DNA than in controls. Thus, our results collectively suggest that AKTIP/Ft1 works in concert with TRF1 to facilitate telomeric DNA replication.
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Affiliation(s)
- Romina Burla
- Dipartimento di Biologia e Biotecnologie, Sapienza—Università di Roma, Roma, Italy
- Istituto Pasteur Fondazione Cenci Bolognetti, Sapienza—Università di Roma, Roma, Italy
| | - Mariateresa Carcuro
- Dipartimento di Biologia e Biotecnologie, Sapienza—Università di Roma, Roma, Italy
- Istituto Pasteur Fondazione Cenci Bolognetti, Sapienza—Università di Roma, Roma, Italy
| | - Grazia D. Raffa
- Dipartimento di Biologia e Biotecnologie, Sapienza—Università di Roma, Roma, Italy
- Istituto Pasteur Fondazione Cenci Bolognetti, Sapienza—Università di Roma, Roma, Italy
| | - Alessandra Galati
- Dipartimento di Biologia e Biotecnologie, Sapienza—Università di Roma, Roma, Italy
- Istituto Pasteur Fondazione Cenci Bolognetti, Sapienza—Università di Roma, Roma, Italy
| | | | - Angela Rizzo
- Istituto Nazionale Tumori Regina Elena, Rome, Italy
| | - Mattia La Torre
- Dipartimento di Biologia e Biotecnologie, Sapienza—Università di Roma, Roma, Italy
- Istituto Pasteur Fondazione Cenci Bolognetti, Sapienza—Università di Roma, Roma, Italy
| | - Emanuela Micheli
- Dipartimento di Biologia e Biotecnologie, Sapienza—Università di Roma, Roma, Italy
- Istituto Pasteur Fondazione Cenci Bolognetti, Sapienza—Università di Roma, Roma, Italy
| | - Laura Ciapponi
- Dipartimento di Biologia e Biotecnologie, Sapienza—Università di Roma, Roma, Italy
- Istituto Pasteur Fondazione Cenci Bolognetti, Sapienza—Università di Roma, Roma, Italy
| | - Giovanni Cenci
- Dipartimento di Biologia e Biotecnologie, Sapienza—Università di Roma, Roma, Italy
- Istituto Pasteur Fondazione Cenci Bolognetti, Sapienza—Università di Roma, Roma, Italy
| | - Enrico Cundari
- Istituto di Biologia e Patologia Molecolari del CNR, Sapienza—Università di Roma, Roma, Italy
| | - Antonio Musio
- Istituto di Ricerca Genetica e Biomedica del CNR, Pisa, and Istituto Toscano Tumori, Firenze, Italy
| | | | - Stefano Cacchione
- Dipartimento di Biologia e Biotecnologie, Sapienza—Università di Roma, Roma, Italy
- Istituto Pasteur Fondazione Cenci Bolognetti, Sapienza—Università di Roma, Roma, Italy
| | - Maurizio Gatti
- Dipartimento di Biologia e Biotecnologie, Sapienza—Università di Roma, Roma, Italy
- Istituto Pasteur Fondazione Cenci Bolognetti, Sapienza—Università di Roma, Roma, Italy
- Istituto di Biologia e Patologia Molecolari del CNR, Sapienza—Università di Roma, Roma, Italy
- * E-mail: (MG); (IS)
| | - Isabella Saggio
- Dipartimento di Biologia e Biotecnologie, Sapienza—Università di Roma, Roma, Italy
- Istituto Pasteur Fondazione Cenci Bolognetti, Sapienza—Università di Roma, Roma, Italy
- Istituto di Biologia e Patologia Molecolari del CNR, Sapienza—Università di Roma, Roma, Italy
- * E-mail: (MG); (IS)
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86
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Boccardi V, Razdan N, Kaplunov J, Mundra JJ, Kimura M, Aviv A, Herbig U. Stn1 is critical for telomere maintenance and long-term viability of somatic human cells. Aging Cell 2015; 14:372-81. [PMID: 25684230 PMCID: PMC4406666 DOI: 10.1111/acel.12289] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/19/2014] [Indexed: 11/29/2022] Open
Abstract
Disruption of telomere maintenance pathways leads to accelerated entry into cellular senescence, a stable proliferative arrest that promotes aging-associated disorders in some mammals. The budding yeast CST complex, comprising Cdc13, Stn1, and Ctc1, is critical for telomere replication, length regulation, and end protection. Although mammalian homologues of CST have been identified recently, their role and function for telomere maintenance in normal somatic human cells are still incompletely understood. Here, we characterize the function of human Stn1 in cultured human fibroblasts and demonstrate its critical role in telomere replication, length regulation, and function. In the absence of high telomerase activity, shRNA-mediated knockdown of hStn1 resulted in aberrant and fragile telomeric structures, stochastic telomere attrition, increased telomere erosion rates, telomere dysfunction, and consequently accelerated entry into cellular senescence. Oxidative stress augmented the defects caused by Stn1 knockdown leading to almost immediate cessation of cell proliferation. In contrast, overexpression of hTERT suppressed some of the defects caused by hStn1 knockdown suggesting that telomerase can partially compensate for hStn1 loss. Our findings reveal a critical role for human Stn1 in telomere length maintenance and function, supporting the model that efficient replication of telomeric repeats is critical for long-term viability of normal somatic mammalian cells.
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Affiliation(s)
- Virginia Boccardi
- Department of Geriatric Medicine and Metabolic Diseases Second University of Naples Naples Italy
| | - Neetu Razdan
- Department of Microbiology, Biochemistry & Molecular Genetics Rutgers Biomedical and Health Sciences Newark NJ USA
| | - Jessica Kaplunov
- Department of Microbiology, Biochemistry & Molecular Genetics Rutgers Biomedical and Health Sciences Newark NJ USA
| | - Jyoti J. Mundra
- Department of Biochemistry and Molecular Biology Rutgers Biomedical and Health Sciences Newark NJ USA
| | - Masayuki Kimura
- Center of Human Development and Aging Rutgers Biomedical and Health Sciences Newark NJ USA
| | - Abraham Aviv
- Center of Human Development and Aging Rutgers Biomedical and Health Sciences Newark NJ USA
| | - Utz Herbig
- Department of Microbiology, Biochemistry & Molecular Genetics Rutgers Biomedical and Health Sciences Newark NJ USA
- New Jersey Medical School‐Cancer Center Rutgers Biomedical and Health Sciences Newark NJ USA
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87
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Beilstein MA, Renfrew KB, Song X, Shakirov EV, Zanis MJ, Shippen DE. Evolution of the Telomere-Associated Protein POT1a in Arabidopsis thaliana Is Characterized by Positive Selection to Reinforce Protein-Protein Interaction. Mol Biol Evol 2015; 32:1329-41. [PMID: 25697340 DOI: 10.1093/molbev/msv025] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Gene duplication is a major driving force in genome evolution. Here, we explore the nature and origin of the POT1 gene duplication in Arabidopsis thaliana. Protection of Telomeres (POT1) is a conserved multifunctional protein that modulates telomerase activity and its engagement with telomeres. Arabidopsis thaliana encodes two divergent POT1 paralogs termed AtPOT1a and AtPOT1b. AtPOT1a positively regulates telomerase activity, whereas AtPOT1b is proposed to negatively regulate telomerase and promote chromosome end protection. Phylogenetic analysis uncovered two independent POT1 duplication events in the plant kingdom, including one at the base of Brassicaceae. Tests for positive selection implemented in PAML revealed that the Brassicaceae POT1a lineage experienced positive selection postduplication and identified three amino acid residues with signatures of positive selection. A sensitive and quantitative genetic complementation assay was developed to assess POT1a function in A. thaliana. The assay showed that AtPOT1a is functionally distinct from single-copy POT1 genes in other plants. Moreover, for two of the sites with a strong signature of positive selection, substitutions that swap the amino acids in AtPOT1a for residues found in AtPOT1b dramatically compromised AtPOT1a function in vivo. In vitro-binding studies demonstrated that all three sites under positive selection specifically enhance the AtPOT1a interaction with CTC1, a core component of the highly conserved CST (CTC1/STN1/TEN1) telomere protein complex. Our results reveal a molecular mechanism for the role of these positively selected sites in AtPOT1a. The data also provide an important empirical example to refine theories of duplicate gene retention, as the outcome of positive selection here appears to be reinforcement of an ancestral function, rather than neofunctionalization. We propose that this outcome may not be unusual when the duplicated protein is a component of a multisubunit complex whose function is in part specified by other members.
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Affiliation(s)
- Mark A Beilstein
- School of Plant Sciences, University of Arizona Department of Biochemistry and Biophysics, Texas A&M University
| | - Kyle B Renfrew
- Department of Biochemistry and Biophysics, Texas A&M University
| | - Xiangyu Song
- Department of Biochemistry and Biophysics, Texas A&M University
| | - Eugene V Shakirov
- Department of Integrative Biology, University of Texas at Austin Institute of Fundamental Medicine and Biology, Kazan (Volga Region) Federal University, Kazan, Republic of Tatarstan, Russia
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88
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Vallabhaneni H, Zhou F, Maul RW, Sarkar J, Yin J, Lei M, Harrington L, Gearhart PJ, Liu Y. Defective repair of uracil causes telomere defects in mouse hematopoietic cells. J Biol Chem 2015; 290:5502-11. [PMID: 25572391 DOI: 10.1074/jbc.m114.607101] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Uracil in the genome can result from misincorporation of dUTP instead of dTTP during DNA synthesis, and is primarily removed by uracil DNA glycosylase (UNG) during base excision repair. Telomeres contain long arrays of TTAGGG repeats and may be susceptible to uracil misincorporation. Using model telomeric DNA substrates, we showed that the position and number of uracil substitutions of thymine in telomeric DNA decreased recognition by the telomere single-strand binding protein, POT1. In primary mouse hematopoietic cells, uracil was detectable at telomeres, and UNG deficiency further increased uracil loads and led to abnormal telomere lengthening. In UNG-deficient cells, the frequencies of sister chromatid exchange and fragility in telomeres also significantly increased in the absence of telomerase. Thus, accumulation of uracil and/or UNG deficiency interferes with telomere maintenance, thereby underscoring the necessity of UNG-initiated base excision repair for the preservation of telomere integrity.
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Affiliation(s)
| | - Fang Zhou
- From the Laboratory of Molecular Gerontology
| | - Robert W Maul
- Laboratory of Molecular Biology and Immunology, NIA, National Institutes of Health, Baltimore, Maryland 21224
| | - Jaya Sarkar
- From the Laboratory of Molecular Gerontology
| | - Jinhu Yin
- From the Laboratory of Molecular Gerontology
| | - Ming Lei
- National Center for Protein Science Shanghai, State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031 China
| | - Lea Harrington
- Department of Medicine, Institute for Research in Immunology and Cancer, University of Montréal, Montréal, Québec H3C 3J7, Canada
| | - Patricia J Gearhart
- Laboratory of Molecular Biology and Immunology, NIA, National Institutes of Health, Baltimore, Maryland 21224,
| | - Yie Liu
- From the Laboratory of Molecular Gerontology,
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89
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The CDC13-STN1-TEN1 complex stimulates Pol α activity by promoting RNA priming and primase-to-polymerase switch. Nat Commun 2014; 5:5762. [PMID: 25503194 PMCID: PMC4269169 DOI: 10.1038/ncomms6762] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Accepted: 11/05/2014] [Indexed: 12/13/2022] Open
Abstract
Emerging evidence suggests that Cdc13-Stn1-Ten1 (CST), an RPA-like ssDNA-binding complex, may regulate primase-Pol α (PP) activity at telomeres constitutively, and at other genomic locations under conditions of replication stress. Here we examine the mechanisms of PP stimulation by CST using purified complexes derived from Candida glabrata. While CST does not enhance isolated DNA polymerase activity, it substantially augments both primase activity and primase-to-polymerase switching. CST also simultaneously shortens the RNA and lengthens the DNA in the chimeric products. Stn1, the most conserved subunit of CST, is alone capable of PP stimulation. Both the N-terminal OB fold and the C-terminal winged-helix domains of Stn1 can bind to the Pol12 subunit of the PP complex, and stimulate PP activity. Our findings provide mechanistic insights on a well-conserved pathway of PP regulation that is critical for genome stability.
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90
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Amiard S, Olivier M, Allain E, Choi K, Smith-Unna R, Henderson IR, White CI, Gallego ME. Telomere stability and development of ctc1 mutants are rescued by inhibition of EJ recombination pathways in a telomerase-dependent manner. Nucleic Acids Res 2014; 42:11979-91. [PMID: 25274733 PMCID: PMC4231758 DOI: 10.1093/nar/gku897] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 09/16/2014] [Accepted: 09/18/2014] [Indexed: 12/11/2022] Open
Abstract
The telomeres of linear eukaryotic chromosomes are protected by caps consisting of evolutionarily conserved nucleoprotein complexes. Telomere dysfunction leads to recombination of chromosome ends and this can result in fusions which initiate chromosomal breakage-fusion-bridge cycles, causing genomic instability and potentially cell death or cancer. We hypothesize that in the absence of the recombination pathways implicated in these fusions, deprotected chromosome ends will instead be eroded by nucleases, also leading to the loss of genes and cell death. In this work, we set out to specifically test this hypothesis in the plant, Arabidopsis. Telomere protection in Arabidopsis implicates KU and CST and their absence leads to chromosome fusions, severe genomic instability and dramatic developmental defects. We have analysed the involvement of end-joining recombination pathways in telomere fusions and the consequences of this on genomic instability and growth. Strikingly, the absence of the multiple end-joining pathways eliminates chromosome fusion and restores normal growth and development to cst ku80 mutant plants. It is thus the chromosomal fusions, per se, which are the underlying cause of the severe developmental defects. This rescue is mediated by telomerase-dependent telomere extension, revealing a competition between telomerase and end-joining recombination proteins for access to deprotected telomeres.
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Affiliation(s)
- Simon Amiard
- Génétique, Reproduction et Développement, UMR CNRS 6293, Clermont Université, INSERM U1103, Aubière, France
| | - Margaux Olivier
- Génétique, Reproduction et Développement, UMR CNRS 6293, Clermont Université, INSERM U1103, Aubière, France
| | - Elisabeth Allain
- Génétique, Reproduction et Développement, UMR CNRS 6293, Clermont Université, INSERM U1103, Aubière, France Department of Plant Sciences, University of Cambridge, Cambridge, UK
| | - Kyuha Choi
- Department of Plant Sciences, University of Cambridge, Cambridge, UK
| | | | - Ian R Henderson
- Department of Plant Sciences, University of Cambridge, Cambridge, UK
| | - Charles I White
- Génétique, Reproduction et Développement, UMR CNRS 6293, Clermont Université, INSERM U1103, Aubière, France
| | - Maria Eugenia Gallego
- Génétique, Reproduction et Développement, UMR CNRS 6293, Clermont Université, INSERM U1103, Aubière, France
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91
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Renfrew KB, Song X, Lee JR, Arora A, Shippen DE. POT1a and components of CST engage telomerase and regulate its activity in Arabidopsis. PLoS Genet 2014; 10:e1004738. [PMID: 25329641 PMCID: PMC4199523 DOI: 10.1371/journal.pgen.1004738] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Accepted: 09/06/2014] [Indexed: 11/18/2022] Open
Abstract
Protection of Telomeres 1 (POT1) is a conserved nucleic acid binding protein implicated in both telomere replication and chromosome end protection. We previously showed that Arabidopsis thaliana POT1a associates with the TER1 telomerase RNP, and is required for telomere length maintenance in vivo. Here we further dissect the function of POT1a and explore its interplay with the CST (CTC1/STN1/TEN1) telomere complex. Analysis of pot1a null mutants revealed that POT1a is not required for telomerase recruitment to telomeres, but is required for telomerase to maintain telomere tracts. We show that POT1a stimulates the synthesis of long telomere repeat arrays by telomerase, likely by enhancing repeat addition processivity. We demonstrate that POT1a binds STN1 and CTC1 in vitro, and further STN1 and CTC1, like POT1a, associate with enzymatically active telomerase in vivo. Unexpectedly, the in vitro interaction of STN1 with TEN1 and POT1a was mutually exclusive, indicating that POT1a and TEN1 may compete for the same binding site on STN1 in vivo. Finally, unlike CTC1 and STN1, TEN1 was not associated with active telomerase in vivo, consistent with our previous data showing that TEN1 negatively regulates telomerase enzyme activity. Altogether, our data support a two-state model in which POT1a promotes an extendable telomere state via contacts with the telomerase RNP as well as STN1 and CTC1, while TEN1 opposes these functions.
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Affiliation(s)
- Kyle B. Renfrew
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, United States of America
| | - Xiangyu Song
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, United States of America
| | - Jung Ro Lee
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, United States of America
| | - Amit Arora
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, United States of America
| | - Dorothy E. Shippen
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, United States of America
- * E-mail:
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92
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Derboven E, Ekker H, Kusenda B, Bulankova P, Riha K. Role of STN1 and DNA polymerase α in telomere stability and genome-wide replication in Arabidopsis. PLoS Genet 2014; 10:e1004682. [PMID: 25299252 PMCID: PMC4191939 DOI: 10.1371/journal.pgen.1004682] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Accepted: 08/19/2014] [Indexed: 11/18/2022] Open
Abstract
The CST (Cdc13/CTC1-STN1-TEN1) complex was proposed to have evolved kingdom specific roles in telomere capping and replication. To shed light on its evolutionary conserved function, we examined the effect of STN1 dysfunction on telomere structure in plants. STN1 inactivation in Arabidopsis leads to a progressive loss of telomeric DNA and the onset of telomeric defects depends on the initial telomere size. While EXO1 aggravates defects associated with STN1 dysfunction, it does not contribute to the formation of long G-overhangs. Instead, these G-overhangs arise, at least partially, from telomerase-mediated telomere extension indicating a deficiency in C-strand fill-in synthesis. Analysis of hypomorphic DNA polymerase α mutants revealed that the impaired function of a general replication factor mimics the telomeric defects associated with CST dysfunction. Furthermore, we show that STN1-deficiency hinders re-replication of heterochromatic regions to a similar extent as polymerase α mutations. This comparative analysis of stn1 and pol α mutants suggests that STN1 plays a genome-wide role in DNA replication and that chromosome-end deprotection in stn1 mutants may represent a manifestation of aberrant replication through telomeres. Telomeres form an elaborate nucleoprotein structure that may represent an obstacle for replication machinery and renders this region prone to fork stalling. CST is an evolutionary conserved complex that was originally discovered to specifically act at telomeres. Interestingly, the function of CST seems to have diverged in the course of evolution; in yeast it is required for telomere protection, while in mammals it was proposed to facilitate replication through telomeres. In plants, inactivation of CST leads to telomere deprotection and genome instability. Here we show that the telomere deprotection in Arabidopsis deficient in STN1, one of the CST components, is consistent with defects in telomere replication and that STN1 phenotypes can be partially phenocopied by an impairment of a general replication factor, DNA polymerase α. In addition, we provide evidence that STN1 facilitates re-replication at non-telomeric loci. This suggests a more general role of CST in genome maintenance and further infers that its seemingly specific function(s) in telomere protection may rather represent unique requirements for efficient replication of telomeric DNA.
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Affiliation(s)
- Elisa Derboven
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna, Austria
| | - Heinz Ekker
- Campus Science Support Facilities, Next Generation Sequencing Facility, Vienna, Austria
| | - Branislav Kusenda
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna, Austria
| | - Petra Bulankova
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna, Austria
| | - Karel Riha
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna, Austria
- Central European Institute of Technology, Masaryk University, Brno, Czech Republic
- * E-mail:
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93
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Holohan B, Wright WE, Shay JW. Cell biology of disease: Telomeropathies: an emerging spectrum disorder. ACTA ACUST UNITED AC 2014; 205:289-99. [PMID: 24821837 PMCID: PMC4018777 DOI: 10.1083/jcb.201401012] [Citation(s) in RCA: 122] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
A constellation of related genetic diseases are caused by defects in the telomere maintenance machinery. These disorders, often referred to as telomeropathies, share symptoms and molecular mechanisms, and mounting evidence indicates they are points along a spectrum of disease. Several new causes of these disorders have been recently discovered, and a number of related syndromes may be unrecognized telomeropathies. Progress in the clinical understanding of telomeropathies has in turn driven progress in the basic science of telomere biology. In addition, the pattern of genetic anticipation in some telomeropathies generates thought-provoking questions about the way telomere length impacts the course of these diseases.
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Affiliation(s)
- Brody Holohan
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
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94
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Shi J, Yang XR, Ballew B, Rotunno M, Calista D, Fargnoli MC, Ghiorzo P, Bressac-de Paillerets B, Nagore E, Avril MF, Caporaso NE, McMaster ML, Cullen M, Wang Z, Zhang X, Bruno W, Pastorino L, Queirolo P, Banuls-Roca J, Garcia-Casado Z, Vaysse A, Mohamdi H, Riazalhosseini Y, Foglio M, Jouenne F, Hua X, Hyland PL, Yin J, Vallabhaneni H, Chai W, Minghetti P, Pellegrini C, Ravichandran S, Eggermont A, Lathrop M, Peris K, Scarra GB, Landi G, Savage SA, Sampson JN, He J, Yeager M, Goldin LR, Demenais F, Chanock SJ, Tucker MA, Goldstein AM, Liu Y, Landi MT. Rare missense variants in POT1 predispose to familial cutaneous malignant melanoma. Nat Genet 2014; 46:482-6. [PMID: 24686846 PMCID: PMC4056593 DOI: 10.1038/ng.2941] [Citation(s) in RCA: 248] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2013] [Accepted: 03/07/2014] [Indexed: 12/15/2022]
Abstract
Although CDKN2A is the most frequent high-risk melanoma susceptibility gene, the underlying genetic factors for most melanoma-prone families remain unknown. Using whole-exome sequencing, we identified a rare variant that arose as a founder mutation in the telomere shelterin gene POT1 (chromosome 7, g.124493086C>T; p.Ser270Asn) in five unrelated melanoma-prone families from Romagna, Italy. Carriers of this variant had increased telomere lengths and numbers of fragile telomeres, suggesting that this variant perturbs telomere maintenance. Two additional rare POT1 variants were identified in all cases sequenced in two separate Italian families, one variant per family, yielding a frequency for POT1 variants comparable to that for CDKN2A mutations in this population. These variants were not found in public databases or in 2,038 genotyped Italian controls. We also identified two rare recurrent POT1 variants in US and French familial melanoma cases. Our findings suggest that POT1 is a major susceptibility gene for familial melanoma in several populations.
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Affiliation(s)
- Jianxin Shi
- 1] Division of Cancer Epidemiology and Genetics, National Cancer Institute, US National Institutes of Health, US Department of Health and Human Services, Bethesda, Maryland, USA. [2]
| | - Xiaohong R Yang
- 1] Division of Cancer Epidemiology and Genetics, National Cancer Institute, US National Institutes of Health, US Department of Health and Human Services, Bethesda, Maryland, USA. [2]
| | - Bari Ballew
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, US National Institutes of Health, US Department of Health and Human Services, Bethesda, Maryland, USA
| | - Melissa Rotunno
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, US National Institutes of Health, US Department of Health and Human Services, Bethesda, Maryland, USA
| | - Donato Calista
- Department of Dermatology, Maurizio Bufalini Hospital, Cesena, Italy
| | | | - Paola Ghiorzo
- 1] Department of Internal Medicine and Medical Specialties, University of Genoa, Genoa, Italy. [2] Genetics of Rare Hereditary Cancers, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) San Martino-IST Istituto Nazionale per la Ricerca sul Cancro, Genoa, Italy
| | | | - Eduardo Nagore
- 1] Department of Dermatology, Instituto Valenciano de Oncología, Valencia, Spain. [2] Department of Dermatology, Universidad Católica de Valencia, Valencia, Spain
| | - Marie Francoise Avril
- Université Paris Descartes, Assistance Publique-Hôpitaux de Paris (AP-HP), Hôpital Cochin, Paris, France
| | - Neil E Caporaso
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, US National Institutes of Health, US Department of Health and Human Services, Bethesda, Maryland, USA
| | - Mary L McMaster
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, US National Institutes of Health, US Department of Health and Human Services, Bethesda, Maryland, USA
| | - Michael Cullen
- 1] Division of Cancer Epidemiology and Genetics, National Cancer Institute, US National Institutes of Health, US Department of Health and Human Services, Bethesda, Maryland, USA. [2] Cancer Genomics Research Laboratory, NCI-Frederick, SAIC-Frederick, Inc., Frederick, Maryland, USA
| | - Zhaoming Wang
- 1] Division of Cancer Epidemiology and Genetics, National Cancer Institute, US National Institutes of Health, US Department of Health and Human Services, Bethesda, Maryland, USA. [2] Cancer Genomics Research Laboratory, NCI-Frederick, SAIC-Frederick, Inc., Frederick, Maryland, USA
| | - Xijun Zhang
- 1] Division of Cancer Epidemiology and Genetics, National Cancer Institute, US National Institutes of Health, US Department of Health and Human Services, Bethesda, Maryland, USA. [2] Cancer Genomics Research Laboratory, NCI-Frederick, SAIC-Frederick, Inc., Frederick, Maryland, USA
| | - William Bruno
- 1] Department of Internal Medicine and Medical Specialties, University of Genoa, Genoa, Italy. [2] Genetics of Rare Hereditary Cancers, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) San Martino-IST Istituto Nazionale per la Ricerca sul Cancro, Genoa, Italy
| | - Lorenza Pastorino
- 1] Department of Internal Medicine and Medical Specialties, University of Genoa, Genoa, Italy. [2] Genetics of Rare Hereditary Cancers, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) San Martino-IST Istituto Nazionale per la Ricerca sul Cancro, Genoa, Italy
| | - Paola Queirolo
- Genetics of Rare Hereditary Cancers, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) San Martino-IST Istituto Nazionale per la Ricerca sul Cancro, Genoa, Italy
| | - Jose Banuls-Roca
- Department of Dermatology, Hospital General Universitario de Alicante, Alicante, Spain
| | - Zaida Garcia-Casado
- Laboratory of Molecular Biology, Instituto Valenciano de Oncología, Valencia, Spain
| | - Amaury Vaysse
- 1] INSERM, UMR 946, Genetic Variation and Human Diseases Unit, Paris, France. [2] Université Paris Diderot, Sorbonne Paris Cité, Institut Universitaire d'Hématologie, Paris, France
| | - Hamida Mohamdi
- 1] INSERM, UMR 946, Genetic Variation and Human Diseases Unit, Paris, France. [2] Université Paris Diderot, Sorbonne Paris Cité, Institut Universitaire d'Hématologie, Paris, France
| | - Yasser Riazalhosseini
- 1] McGill University and Génome Québec Innovation Centre, Montreal, Quebec, Canada. [2] Department of Human Genetics, McGill University, Montreal, Quebec, Canada
| | | | | | - Xing Hua
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, US National Institutes of Health, US Department of Health and Human Services, Bethesda, Maryland, USA
| | - Paula L Hyland
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, US National Institutes of Health, US Department of Health and Human Services, Bethesda, Maryland, USA
| | - Jinhu Yin
- Laboratory of Molecular Gerontology, National Institute on Aging, US National Institutes of Health, US Department of Health and Human Services, Baltimore, Maryland, USA
| | - Haritha Vallabhaneni
- Laboratory of Molecular Gerontology, National Institute on Aging, US National Institutes of Health, US Department of Health and Human Services, Baltimore, Maryland, USA
| | - Weihang Chai
- Section of Medical Sciences, School of Molecular Biosciences, Washington State University, Spokane, Washington, USA
| | - Paola Minghetti
- Department of Dermatology, Maurizio Bufalini Hospital, Cesena, Italy
| | - Cristina Pellegrini
- Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy
| | - Sarangan Ravichandran
- SAIC-Frederick, Inc., Frederick National Laboratory for Cancer Research, Simulation, Analysis and Mathematical Modeling Group, Advanced Biomedical Computing Center, Frederick, Maryland, USA
| | - Alexander Eggermont
- 1] Service de Génétique, Gustave Roussy, Villejuif, France. [2] Université Paris-Sud, Kremlin Bicêtre France, Gustave Roussy, Villejuif, France
| | - Mark Lathrop
- 1] McGill University and Génome Québec Innovation Centre, Montreal, Quebec, Canada. [2] Department of Human Genetics, McGill University, Montreal, Quebec, Canada. [3] Fondation Jean Dausset-Centre d'Etude du Polymorphisme Humain (CEPH), Paris, France
| | - Ketty Peris
- Department of Dermatology, University of L'Aquila, L'Aquila, Italy
| | | | - Giorgio Landi
- Department of Dermatology, Maurizio Bufalini Hospital, Cesena, Italy
| | - Sharon A Savage
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, US National Institutes of Health, US Department of Health and Human Services, Bethesda, Maryland, USA
| | - Joshua N Sampson
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, US National Institutes of Health, US Department of Health and Human Services, Bethesda, Maryland, USA
| | - Ji He
- 1] Division of Cancer Epidemiology and Genetics, National Cancer Institute, US National Institutes of Health, US Department of Health and Human Services, Bethesda, Maryland, USA. [2] Cancer Genomics Research Laboratory, NCI-Frederick, SAIC-Frederick, Inc., Frederick, Maryland, USA
| | - Meredith Yeager
- 1] Division of Cancer Epidemiology and Genetics, National Cancer Institute, US National Institutes of Health, US Department of Health and Human Services, Bethesda, Maryland, USA. [2] Cancer Genomics Research Laboratory, NCI-Frederick, SAIC-Frederick, Inc., Frederick, Maryland, USA
| | - Lynn R Goldin
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, US National Institutes of Health, US Department of Health and Human Services, Bethesda, Maryland, USA
| | - Florence Demenais
- 1] INSERM, UMR 946, Genetic Variation and Human Diseases Unit, Paris, France. [2] Université Paris Diderot, Sorbonne Paris Cité, Institut Universitaire d'Hématologie, Paris, France
| | - Stephen J Chanock
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, US National Institutes of Health, US Department of Health and Human Services, Bethesda, Maryland, USA
| | - Margaret A Tucker
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, US National Institutes of Health, US Department of Health and Human Services, Bethesda, Maryland, USA
| | - Alisa M Goldstein
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, US National Institutes of Health, US Department of Health and Human Services, Bethesda, Maryland, USA
| | - Yie Liu
- Laboratory of Molecular Gerontology, National Institute on Aging, US National Institutes of Health, US Department of Health and Human Services, Baltimore, Maryland, USA
| | - Maria Teresa Landi
- 1] Division of Cancer Epidemiology and Genetics, National Cancer Institute, US National Institutes of Health, US Department of Health and Human Services, Bethesda, Maryland, USA. [2]
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95
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Luo YM, Xia NX, Yang L, Li Z, Yang H, Yu HJ, Liu Y, Lei H, Zhou FX, Xie CH, Zhou YF. CTC1 increases the radioresistance of human melanoma cells by inhibiting telomere shortening and apoptosis. Int J Mol Med 2014; 33:1484-90. [PMID: 24718655 PMCID: PMC4055431 DOI: 10.3892/ijmm.2014.1721] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Accepted: 03/19/2014] [Indexed: 02/07/2023] Open
Abstract
Melanoma has traditionally been viewed as a radioresistant cancer. However, recent studies suggest that under certain clinical circumstances, radiotherapy may play a significant role in the treatment of melanoma. Previous studies have demonstrated that telomere length is a hallmark of radiosensitivity. The newly discovered mammalian CTC1-STN1-TEN1 (CST) complex has been demonstrated to be an important telomere maintenance factor. In this study, by establishing a radiosensitive/radioresistant human melanoma cell model, MDA-MB-435/MDA-MB-435R, we aimed to investigate the association of CTC1 expression with radiosensitivity in human melanoma cell lines, and to elucidate the possible underlying mechanisms. We found that CTC1 mRNA and protein levels were markedly increased in the MDA-MB-435R cells compared with the MDA-MB-435 cells. Moreover, the downregulation of CTC1 enhanced radiosensitivity, induced DNA damage and promoted telomere shortening and apoptosis in both cell lines. Taken together, our findings suggest that CTC1 increases the radioresistance of human melanoma cells by inhibiting telomere shortening and apoptosis. Thus, CTC1 may be an attractive target gene for the treatment of human melanoma.
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Affiliation(s)
- Y M Luo
- Hubei Cancer Clinical Study Center, Hubei Key Laboratory of Tumor Biological Behaviors, Wuhan University, Wuhan, Hubei, P.R. China
| | - N X Xia
- Hubei Cancer Clinical Study Center, Hubei Key Laboratory of Tumor Biological Behaviors, Wuhan University, Wuhan, Hubei, P.R. China
| | - L Yang
- Hubei Cancer Clinical Study Center, Hubei Key Laboratory of Tumor Biological Behaviors, Wuhan University, Wuhan, Hubei, P.R. China
| | - Z Li
- Hubei Cancer Clinical Study Center, Hubei Key Laboratory of Tumor Biological Behaviors, Wuhan University, Wuhan, Hubei, P.R. China
| | - H Yang
- Hubei Cancer Clinical Study Center, Hubei Key Laboratory of Tumor Biological Behaviors, Wuhan University, Wuhan, Hubei, P.R. China
| | - H J Yu
- Hubei Cancer Clinical Study Center, Hubei Key Laboratory of Tumor Biological Behaviors, Wuhan University, Wuhan, Hubei, P.R. China
| | - Y Liu
- Hubei Cancer Clinical Study Center, Hubei Key Laboratory of Tumor Biological Behaviors, Wuhan University, Wuhan, Hubei, P.R. China
| | - H Lei
- Hubei Cancer Clinical Study Center, Hubei Key Laboratory of Tumor Biological Behaviors, Wuhan University, Wuhan, Hubei, P.R. China
| | - F X Zhou
- Hubei Cancer Clinical Study Center, Hubei Key Laboratory of Tumor Biological Behaviors, Wuhan University, Wuhan, Hubei, P.R. China
| | - C H Xie
- Hubei Cancer Clinical Study Center, Hubei Key Laboratory of Tumor Biological Behaviors, Wuhan University, Wuhan, Hubei, P.R. China
| | - Y F Zhou
- Department of Radiation Oncology and Medical Oncology, Zhongnan Hospital, Wuhan University, Wuhan, Hubei, P.R. China
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96
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Transcriptional analysis of apoptotic cerebellar granule neurons following rescue by gastric inhibitory polypeptide. Int J Mol Sci 2014; 15:5596-622. [PMID: 24694544 PMCID: PMC4013584 DOI: 10.3390/ijms15045596] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Revised: 03/04/2014] [Accepted: 03/17/2014] [Indexed: 12/31/2022] Open
Abstract
Apoptosis triggered by exogenous or endogenous stimuli is a crucial phenomenon to determine the fate of neurons, both in physiological and in pathological conditions. Our previous study established that gastric inhibitory polypeptide (Gip) is a neurotrophic factor capable of preventing apoptosis of cerebellar granule neurons (CGNs), during its pre-commitment phase. In the present study, we conducted whole-genome expression profiling to obtain a comprehensive view of the transcriptional program underlying the rescue effect of Gip in CGNs. By using DNA microarray technology, we identified 65 genes, we named survival related genes, whose expression is significantly de-regulated following Gip treatment. The expression levels of six transcripts were confirmed by real-time quantitative polymerase chain reaction. The proteins encoded by the survival related genes are functionally grouped in the following categories: signal transduction, transcription, cell cycle, chromatin remodeling, cell death, antioxidant activity, ubiquitination, metabolism and cytoskeletal organization. Our data outline that Gip supports CGNs rescue via a molecular framework, orchestrated by a wide spectrum of gene actors, which propagate survival signals and support neuronal viability.
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97
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Fulcher N, Derboven E, Valuchova S, Riha K. If the cap fits, wear it: an overview of telomeric structures over evolution. Cell Mol Life Sci 2014; 71:847-65. [PMID: 24042202 PMCID: PMC11113737 DOI: 10.1007/s00018-013-1469-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Revised: 08/16/2013] [Accepted: 08/30/2013] [Indexed: 10/26/2022]
Abstract
Genome organization into linear chromosomes likely represents an important evolutionary innovation that has permitted the development of the sexual life cycle; this process has consequently advanced nuclear expansion and increased complexity of eukaryotic genomes. Chromosome linearity, however, poses a major challenge to the internal cellular machinery. The need to efficiently recognize and repair DNA double-strand breaks that occur as a consequence of DNA damage presents a constant threat to native chromosome ends known as telomeres. In this review, we present a comparative survey of various solutions to the end protection problem, maintaining an emphasis on DNA structure. This begins with telomeric structures derived from a subset of prokaryotes, mitochondria, and viruses, and will progress into the typical telomere structure exhibited by higher organisms containing TTAGG-like tandem sequences. We next examine non-canonical telomeres from Drosophila melanogaster, which comprise arrays of retrotransposons. Finally, we discuss telomeric structures in evolution and possible switches between canonical and non-canonical solutions to chromosome end protection.
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Affiliation(s)
- Nick Fulcher
- Gregor Mendel Institute, Austrian Academy of Sciences, Dr. Bohrgasse 3, 1030 Vienna, Austria
| | - Elisa Derboven
- Gregor Mendel Institute, Austrian Academy of Sciences, Dr. Bohrgasse 3, 1030 Vienna, Austria
| | - Sona Valuchova
- Gregor Mendel Institute, Austrian Academy of Sciences, Dr. Bohrgasse 3, 1030 Vienna, Austria
| | - Karel Riha
- Gregor Mendel Institute, Austrian Academy of Sciences, Dr. Bohrgasse 3, 1030 Vienna, Austria
- Central European Institute of Technology, Kamenice 753/5, Brno, Czech Republic
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98
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Boltz KA, Jasti M, Townley JM, Shippen DE. Analysis of poly(ADP-Ribose) polymerases in Arabidopsis telomere biology. PLoS One 2014; 9:e88872. [PMID: 24551184 PMCID: PMC3923816 DOI: 10.1371/journal.pone.0088872] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2013] [Accepted: 01/17/2014] [Indexed: 11/22/2022] Open
Abstract
Maintaining the length of the telomere tract at chromosome ends is a complex process vital to normal cell division. Telomere length is controlled through the action of telomerase as well as a cadre of telomere-associated proteins that facilitate replication of the chromosome end and protect it from eliciting a DNA damage response. In vertebrates, multiple poly(ADP-ribose) polymerases (PARPs) have been implicated in the regulation of telomere length, telomerase activity and chromosome end protection. Here we investigate the role of PARPs in plant telomere biology. We analyzed Arabidopsis thaliana mutants null for PARP1 and PARP2 as well as plants treated with the PARP competitive inhibitor 3-AB. Plants deficient in PARP were hypersensitive to genotoxic stress, and expression of PARP1 and PARP2 mRNA was elevated in response to MMS or zeocin treatment or by the loss of telomerase. Additionally, PARP1 mRNA was induced in parp2 mutants, and conversely, PARP2 mRNA was induced in parp1 mutants. PARP3 mRNA, by contrast, was elevated in both parp1 and parp2 mutants, but not in seedlings treated with 3-AB or zeocin. PARP mutants and 3-AB treated plants displayed robust telomerase activity, no significant changes in telomere length, and no end-to-end chromosome fusions. Although there remains a possibility that PARPs play a role in Arabidopsis telomere biology, these findings argue that the contribution is a minor one.
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Affiliation(s)
- Kara A. Boltz
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, United States of America
| | - Madhu Jasti
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, United States of America
| | - Jennifer M. Townley
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, United States of America
| | - Dorothy E. Shippen
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, United States of America
- * E-mail:
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99
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Short telomeres: from dyskeratosis congenita to sporadic aplastic anemia and malignancy. Transl Res 2013; 162:353-63. [PMID: 23732052 PMCID: PMC3834083 DOI: 10.1016/j.trsl.2013.05.003] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2013] [Revised: 05/06/2013] [Accepted: 05/09/2013] [Indexed: 12/20/2022]
Abstract
Telomeres are DNA-protein structures that form a protective cap on chromosome ends. As such, they prevent the natural ends of linear chromosomes from being subjected to DNA repair activities that would result in telomere fusion, degradation, or recombination. Both the DNA and protein components of the telomere are required for this essential function, because insufficient telomeric DNA length, loss of the terminal telomeric DNA structure, or deficiency of key telomere-associated factors may elicit a DNA damage response and result in cellular senescence or apoptosis. In the setting of failed checkpoint mechanisms, such DNA-protein defects can also lead to genomic instability through telomere fusions or recombination. Thus, as shown in both model systems and in humans, defects in telomere biology are implicated in cellular and organismal aging as well as in tumorigenesis. Bone marrow failure and malignancy are 2 life-threatening disease manifestations in the inherited telomere biology disorder dyskeratosis congenita. We provide an overview of basic telomere structure and maintenance. We outline the telomere biology defects observed in dyskeratosis congenita, focusing on recent discoveries in this field. Last, we review the evidence of how telomere biology may impact sporadic aplastic anemia and the risk for various cancers.
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100
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Gu P, Chang S. Functional characterization of human CTC1 mutations reveals novel mechanisms responsible for the pathogenesis of the telomere disease Coats plus. Aging Cell 2013; 12:1100-9. [PMID: 23869908 DOI: 10.1111/acel.12139] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/10/2013] [Indexed: 11/29/2022] Open
Abstract
Coats plus is a rare recessive disorder characterized by intracranial calcifications, hematological abnormalities, and retinal vascular defects. This disease results from mutations in CTC1, a member of the CTC1-STN1-TEN1 (CST) complex critical for telomere replication. Telomeres are specialized DNA/protein structures essential for the maintenance of genome stability. Several patients with Coats plus display critically shortened telomeres, suggesting that telomere dysfunction plays an important role in disease pathogenesis. These patients inherit CTC1 mutations in a compound heterozygous manner, with one allele encoding a frameshift mutant and the other a missense mutant. How these mutations impact upon telomere function is unknown. We report here the first biochemical characterization of human CTC1 mutations. We found that all CTC1 frameshift mutations generated truncated or unstable protein products, none of which were able to form a complex with STN1-TEN1 on telomeres, resulting in progressive telomere shortening and formation of fused chromosomes. Missense mutations are able to form the CST complex at telomeres, but their expression levels are often repressed by the frameshift mutants. Our results also demonstrate for the first time that CTC1 mutations promote telomere dysfunction by decreasing the stability of STN1 to reduce its ability to interact with DNA Polα, thus highlighting a previously unknown mechanism to induce telomere dysfunction.
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Affiliation(s)
- Peili Gu
- Department of Laboratory Medicine; Yale University School of Medicine; 330 Cedar Street New Haven CT 06520 USA
| | - Sandy Chang
- Department of Laboratory Medicine; Yale University School of Medicine; 330 Cedar Street New Haven CT 06520 USA
- Department of Pathology; Yale University School of Medicine; 330 Cedar Street New Haven CT 06520 USA
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