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Liu XY, Tan Q, Li LX. A pan-cancer analysis of Dyskeratosis congenita 1 (DKC1) as a prognostic biomarker. Hereditas 2023; 160:38. [PMID: 38082360 PMCID: PMC10712082 DOI: 10.1186/s41065-023-00302-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 11/20/2023] [Indexed: 12/18/2023] Open
Abstract
BACKGROUND Dyskeratosis congenita 1 (DKC1), a critical component of telomerase complex, is highly expressed in a variety of human cancers. However, the association of DKC1 with cancer occurrence and development stages is not clear, making a pan-cancer analysis crucial. METHODS We conducted a study using various bioinformatic databases such as TIMER, GEPIA, UALCAN, and KM plotter Analysis to examine the different expressions of DKC1 in multiple tissues and its correlation with pathological stages. Through KEGG analysis, GO enrichment analysis and Venn analysis, we were able to reveal DKC1-associated genes and signaling pathways. In addition, we performed several tests including the CCK, wound healing assay, cell cycle arrest assay, transwell assay and Sa-β-gal staining on DKC1-deleted MDA-231 cells. RESULTS Our study demonstrates that DKC1 has relatively low expression specificity in different tissues. Furthermore, we found that in ACC, KICH, KIRP and LIHC, the expression level of DKC1 is positively correlated with pathological stages. Conversely, in NHSC, KIRP, LGG, LIHC, MESO and SARC, we observed a negative influence of DKC1 expression level on the overall survival rate. We also found a significant positive correlation between DKC1 expression and Tumor Mutational Burden in 14 tumors. Additionally, we observed a significantly negative impact of DKC1 DNA methylation on gene expression at the promoter region in BRCA. We also identified numerous phosphorylation sites concentrated at the C-terminus of the DKC1 protein. Our GO analysis revealed a correlation between DKC1 and ribosomal biosynthesis pathways, and the common element UTP14A was identified. We also observed decreased rates of cell proliferation, migration and invasion abilities in DKC1-knockout MDA-MB-231 cell lines. Furthermore, DKC1-knockout induced cell cycle arrest and caused cell senescence. CONCLUSIONS Our findings suggest that the precise expression of DKC1 is closely associated with the occurrence and developmental stages of cancer in multiple tissues. Depletion of DKC1 can inhibit the abilities of cancer cells to proliferate, migrate, and invade by arresting the cell cycle and inducing cell senescence. Therefore, DKC1 may be a valuable prognostic biomarker for the diagnosis and treatment of cancer in various tissues.
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Affiliation(s)
- Xin-Ying Liu
- School of Life and Health Sciences, Huzhou College, Huzhou, 313000, China
- Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200233, China
| | - Qing Tan
- State Key Laboratory of Medical Molecular Biology, Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100005, China
| | - Lin-Xiao Li
- School of Life and Health Sciences, Huzhou College, Huzhou, 313000, China.
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Westin ER, Khodadadi-Jamayran A, Pham LK, Tung ML, Goldman FD. CRISPR screen identifies CEBPB as contributor to dyskeratosis congenita fibroblast senescence via augmented inflammatory gene response. G3 (Bethesda) 2023; 13:jkad207. [PMID: 37717172 PMCID: PMC10627266 DOI: 10.1093/g3journal/jkad207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 08/16/2023] [Accepted: 08/17/2023] [Indexed: 09/18/2023]
Abstract
Aging is the consequence of intra- and extracellular events that promote cellular senescence. Dyskeratosis congenita (DC) is an example of a premature aging disorder caused by underlying telomere/telomerase-related mutations. Cells from these patients offer an opportunity to study telomere-related aging and senescence. Our previous work has found that telomere shortening stimulates DNA damage responses (DDRs) and increases reactive oxygen species (ROS), thereby promoting entry into senescence. This work also found that telomere elongation via TERT expression, the catalytic component of the telomere-elongating enzyme telomerase, or p53 shRNA could decrease ROS by disrupting this telomere-DDR-ROS pathway. To further characterize this pathway, we performed a CRISPR/Cas9 knockout screen to identify genes that extend life span in DC cells. Of the cellular clones isolated due to increased life span, 34% had a guide RNA (gRNA) targeting CEBPB, while gRNAs targeting WSB1, MED28, and p73 were observed multiple times. CEBPB is a transcription factor associated with activation of proinflammatory response genes suggesting that inflammation may be present in DC cells. The inflammatory response was investigated using RNA sequencing to compare DC and control cells. Expression of inflammatory genes was found to be significantly elevated (P < 0.0001) in addition to a key subset of these inflammation-related genes [IL1B, IL6, IL8, IL12A, CXCL1 (GROa), CXCL2 (GROb), and CXCL5]. which are regulated by CEBPB. Exogenous TERT expression led to downregulation of RNA/protein CEBPB expression and the inflammatory response genes suggesting a telomere length-dependent mechanism to regulate CEBPB. Furthermore, unlike exogenous TERT and p53 shRNA, CEBPB shRNA did not significantly decrease ROS suggesting that CEBPB's contribution in DC cells' senescence is ROS independent. Our findings demonstrate a key role for CEBPB in engaging senescence by mobilizing an inflammatory response within DC cells.
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Affiliation(s)
- Erik R Westin
- Department of Pediatrics, Division of Hematology Oncology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
- Department of Cancer Precision Medicine, Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, LA 70808, USA
| | - Alireza Khodadadi-Jamayran
- Genome Technology Center, Applied Bioinformatics Laboratories, NYU Langone Medical Center, New York, NY 10016, USA
| | - Linh K Pham
- Department of Pediatrics, Division of Hematology Oncology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Moon Ley Tung
- Stead Family Department of Pediatrics, Division of Medical Genetics and Genomics, University of Iowa, Iowa City, IA 52242, USA
| | - Frederick D Goldman
- Department of Pediatrics, Division of Hematology Oncology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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3
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Stock AJ, Ayyar S, Kashyap A, Wang Y, Yanai H, Starost MF, Tanaka-Yano M, Bodogai M, Sun C, Wang Y, Gong Y, Puligilla C, Fang EF, Bohr VA, Liu Y, Beerman I. Boosting NAD ameliorates hematopoietic impairment linked to short telomeres in vivo. GeroScience 2023; 45:2213-2228. [PMID: 36826621 PMCID: PMC10651621 DOI: 10.1007/s11357-023-00752-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Accepted: 02/03/2023] [Indexed: 02/25/2023] Open
Abstract
Short telomeres are a defining feature of telomere biology disorders (TBDs), including dyskeratosis congenita (DC), for which there is no effective general cure. Patients with TBDs often experience bone marrow failure. NAD, an essential metabolic coenzyme, is decreased in models of DC. Herein, using telomerase reverse transcriptase null (Tert-/-) mice with critically short telomeres, we investigated the effect of NAD supplementation with the NAD precursor, nicotinamide riboside (NR), on features of health span disrupted by telomere impairment. Our results revealed that NR ameliorated body weight loss in Tert-/- mice and improved telomere integrity and telomere dysfunction-induced systemic inflammation. NR supplementation also mitigated myeloid skewing of Tert-/- hematopoietic stem cells. Furthermore, NR alleviated villous atrophy and inflammation in the small intestine of Tert-/- transplant recipient mice. Altogether, our findings support NAD intervention as a potential therapeutic strategy to enhance aspects of health span compromised by telomere attrition.
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Affiliation(s)
- Amanda J Stock
- Laboratory of Genetics and Genomics, Biomedical Research Center, National Institute On Aging/National Institutes of Health, 251 Bayview Blvd., Baltimore, MD, USA
| | - Saipriya Ayyar
- Translational Gerontology Branch, Biomedical Research Center, National Institute On Aging/National Institutes of Health, 251 Bayview Blvd., Baltimore, MD, USA
| | - Amogh Kashyap
- Translational Gerontology Branch, Biomedical Research Center, National Institute On Aging/National Institutes of Health, 251 Bayview Blvd., Baltimore, MD, USA
| | - Yunong Wang
- Laboratory of Genetics and Genomics, Biomedical Research Center, National Institute On Aging/National Institutes of Health, 251 Bayview Blvd., Baltimore, MD, USA
| | - Hagai Yanai
- Translational Gerontology Branch, Biomedical Research Center, National Institute On Aging/National Institutes of Health, 251 Bayview Blvd., Baltimore, MD, USA
| | - Matthew F Starost
- Division of Veterinary Resources, Building 14E, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD, USA
| | - Mayuri Tanaka-Yano
- Translational Gerontology Branch, Biomedical Research Center, National Institute On Aging/National Institutes of Health, 251 Bayview Blvd., Baltimore, MD, USA
| | - Monica Bodogai
- Laboratory of Molecular Biology and Immunology, Biomedical Research Center, National Institute On Aging/National Institutes of Health, 251 Bayview Blvd., Baltimore, MD, USA
| | - Chongkui Sun
- Laboratory of Genetics and Genomics, Biomedical Research Center, National Institute On Aging/National Institutes of Health, 251 Bayview Blvd., Baltimore, MD, USA
| | - Yajun Wang
- Laboratory of Genetics and Genomics, Biomedical Research Center, National Institute On Aging/National Institutes of Health, 251 Bayview Blvd., Baltimore, MD, USA
| | - Yi Gong
- Laboratory of Genetics and Genomics, Biomedical Research Center, National Institute On Aging/National Institutes of Health, 251 Bayview Blvd., Baltimore, MD, USA
| | - Chandrakala Puligilla
- Laboratory of Genetics and Genomics, Biomedical Research Center, National Institute On Aging/National Institutes of Health, 251 Bayview Blvd., Baltimore, MD, USA
| | - Evandro F Fang
- DNA Repair Section, Biomedical Research Center, National Institute On Aging/National Institutes of Health, 251 Bayview Blvd., Baltimore, MD, USA
- Department of Clinical Molecular Biology, University of Oslo and Akershus University Hospital, 1478, Lørenskog, Norway
| | - Vilhelm A Bohr
- DNA Repair Section, Biomedical Research Center, National Institute On Aging/National Institutes of Health, 251 Bayview Blvd., Baltimore, MD, USA
| | - Yie Liu
- Laboratory of Genetics and Genomics, Biomedical Research Center, National Institute On Aging/National Institutes of Health, 251 Bayview Blvd., Baltimore, MD, USA.
| | - Isabel Beerman
- Translational Gerontology Branch, Biomedical Research Center, National Institute On Aging/National Institutes of Health, 251 Bayview Blvd., Baltimore, MD, USA.
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4
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He M, Lian G, Hu H, He H, Wang M. Compound heterozygous mutations in the helicase RTEL1 causing Hoyeraal-Hreidarsson syndrome with Blake`s pouch cyst: a case report. Turk J Pediatr 2023; 65:845-852. [PMID: 37853975 DOI: 10.24953/turkjped.2022.344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2023]
Abstract
BACKGROUND Telomeres inhibit DNA damage response at the ends of the chromosome to suppress cell cycle arrest as well as ensure genome stability. Dyskeratosis congenita (DC), a telomere-related disease, includes the classical triad involving oral leukoplakia, dysplastic nails, and lacy reticular pigment in the neck and/or upper chest. Hoyeraal-Hreidarrson syndrome (HHS), a severe manifestation of DC, frequently occurs during childhood, and patients with HHS often show short-term survival and thus do not exhibit all mucocutaneous manifestations or syndromic features. CASE We report here a patient with HHS characterized by the proband`s clinical attributes, such as growth delay, bone marrow failure, microcephaly, defects in body development, and the absence of cerebellar hypoplasia combined with Blake`s pouch cyst. By using exome sequencing, novel compound heterozygous mutations (c.1451C > T and c.1266+3del78bp) were detected in the RTEL1 (regulator of telomere elongation helicase 1) gene. CONCLUSIONS The DNA helicase RTEL1 plays a role in genome stability, DNA replication, telomere maintenance, and genome repair. Terminal restriction fragment length analysis revealed a significantly shorter telomere length of the proband. Our findings provided evidence that compound heterozygous RTEL1 mutations cause HHS.
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Affiliation(s)
- Min He
- Department of Pediatric, the First Affiliated Hospital of Xi'an Jiaotong University, Xi 'an 710061, People's Republic of China
| | - GuoLi Lian
- Department of Pediatric, the First Affiliated Hospital of Xi'an Jiaotong University, Xi 'an 710061, People's Republic of China
| | - HaiPeng Hu
- Department of Pediatric, the First Affiliated Hospital of Xi'an Jiaotong University, Xi 'an 710061, People's Republic of China
| | - Huan He
- Department of Pediatric, the First Affiliated Hospital of Xi'an Jiaotong University, Xi 'an 710061, People's Republic of China
| | - Miaomiao Wang
- Department of Pediatric, the First Affiliated Hospital of Xi'an Jiaotong University, Xi 'an 710061, People's Republic of China
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5
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Batista LFZ, Dokal I, Parker R. Telomere biology disorders: time for moving towards the clinic? Trends Mol Med 2022; 28:882-891. [PMID: 36057525 PMCID: PMC9509473 DOI: 10.1016/j.molmed.2022.08.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 07/29/2022] [Accepted: 08/01/2022] [Indexed: 11/19/2022]
Abstract
Telomere biology disorders (TBDs) are a group of rare diseases caused by mutations that impair telomere maintenance. Mutations that cause reduced levels of TERC/hTR, the telomerase RNA component, are found in most TBD patients and include loss-of-function mutations in hTR itself, in hTR-binding proteins [NOP10, NHP2, NAF1, ZCCHC8, and dyskerin (DKC1)], and in proteins required for hTR processing (PARN). These patients show diverse clinical presentations that most commonly include bone marrow failure (BMF)/aplastic anemia (AA), pulmonary fibrosis, and liver cirrhosis. There are no curative therapies for TBD patients. An understanding of hTR biogenesis, maturation, and degradation has identified pathways and pharmacological agents targeting the poly(A) polymerase PAPD5, which adds 3'-oligoadenosine tails to hTR to promote hTR degradation, and TGS1, which modifies the 5'-cap structure of hTR to enhance degradation, as possible therapeutic approaches. Critical next steps will be clinical trials to establish the effectiveness and potential side effects of these compounds in TBD patients.
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Affiliation(s)
- Luis F Z Batista
- Department of Medicine, Washington University in St. Louis, St. Louis, MO, USA; Center for Genome Integrity, Washington University in St. Louis, St. Louis, MO, USA; Center of Regenerative Medicine, Washington University in St. Louis, St. Louis, MO, USA.
| | - Inderjeet Dokal
- Centre for Genomics and Child Health, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
| | - Roy Parker
- Department of Biochemistry and Biofrontiers Instiute, University of Colorado, Boulder, CO, USA; Department of Biochemistry, University of Colorado Boulder, Boulder, CO, USA; Howard Hughes Medical Institute, Chevy Chase, MD, USA.
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6
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Kermasson L, Churikov D, Awad A, Smoom R, Lainey E, Touzot F, Audebert-Bellanger S, Haro S, Roger L, Costa E, Mouf M, Bottero A, Oleastro M, Abdo C, de Villartay JP, Géli V, Tzfati Y, Callebaut I, Danielian S, Soares G, Kannengiesser C, Revy P. Inherited human Apollo deficiency causes severe bone marrow failure and developmental defects. Blood 2022; 139:2427-2440. [PMID: 35007328 PMCID: PMC11022855 DOI: 10.1182/blood.2021010791] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 12/13/2021] [Indexed: 11/20/2022] Open
Abstract
Inherited bone marrow failure syndromes (IBMFSs) are a group of disorders typified by impaired production of 1 or several blood cell types. The telomere biology disorders dyskeratosis congenita (DC) and its severe variant, Høyeraal-Hreidarsson (HH) syndrome, are rare IBMFSs characterized by bone marrow failure, developmental defects, and various premature aging complications associated with critically short telomeres. We identified biallelic variants in the gene encoding the 5'-to-3' DNA exonuclease Apollo/SNM1B in 3 unrelated patients presenting with a DC/HH phenotype consisting of early-onset hypocellular bone marrow failure, B and NK lymphopenia, developmental anomalies, microcephaly, and/or intrauterine growth retardation. All 3 patients carry a homozygous or compound heterozygous (in combination with a null allele) missense variant affecting the same residue L142 (L142F or L142S) located in the catalytic domain of Apollo. Apollo-deficient cells from patients exhibited spontaneous chromosome instability and impaired DNA repair that was complemented by CRISPR/Cas9-mediated gene correction. Furthermore, patients' cells showed signs of telomere fragility that were not associated with global reduction of telomere length. Unlike patients' cells, human Apollo KO HT1080 cell lines showed strong telomere dysfunction accompanied by excessive telomere shortening, suggesting that the L142S and L142F Apollo variants are hypomorphic. Collectively, these findings define human Apollo as a genome caretaker and identify biallelic Apollo variants as a genetic cause of a hitherto unrecognized severe IBMFS that combines clinical hallmarks of DC/HH with normal telomere length.
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Affiliation(s)
- Laëtitia Kermasson
- Laboratory of Genome Dynamics in the Immune System, Laboratoire labellisé Ligue Naionale contre le Cancer, INSERM UMR 1163, Université de Paris, Imagine Institute, Paris, France
| | - Dmitri Churikov
- U1068 INSERM, Unité Mixte de Recherche (UMR) 7258 (CNRS), Equipe Labellisée Ligue Nationale Contre le Cancer, Marseille Cancer Research Center (CRCM), Institut Paoli-Calmettes, Aix Marseille University, Marseille, France
| | - Aya Awad
- Department of Genetics, The Silberman Institute of Life Science, The Hebrew University of Jerusalem, Safra Campus-Givat Ram, Jerusalem, Israel
| | - Riham Smoom
- Department of Genetics, The Silberman Institute of Life Science, The Hebrew University of Jerusalem, Safra Campus-Givat Ram, Jerusalem, Israel
| | - Elodie Lainey
- Hematology Laboratory, Robert Debré Hospital-Assistance Publique-Hôpitaux de Paris (APHP); INSERM UMR 1131-Hematology University Institute-Denis Diderot School of Medicine, Paris, France
| | - Fabien Touzot
- Department of Immunology-Rheumatology, Department of Pediatrics, Centre Hospitalier Universitaire (CHU), Sainte Justine Research Center, Université de Montréal, Montréal, Quebec, Canada
| | | | - Sophie Haro
- Department of Paediatrics and Medical Genetics, CHU de Brest, Brest, France
| | - Lauréline Roger
- Structure and Instability of Genomes laboratory, “Muséum National d'Histoire Naturelle” (MNHN), INSERM U1154, CNRS UMR 7196, Paris, France
| | - Emilia Costa
- Serviço de Pediatria, Centro Hospitalar e Universitário do Porto, Porto, Portugal
| | - Maload Mouf
- 68HAL Meddle Laboratory, Zenon Skelter Institute, Green Hills, Eggum, Norway
| | | | - Matias Oleastro
- Rheumathology and Immunology Service, Hospital Nacional de Pediatría JP Garrahan, Buenos Aires, Argentina
| | - Chrystelle Abdo
- Onco-Hematology, Assistance Publique-Hôpitaux de Paris, Université de Paris and Institut Necker Enfants Malades, Paris, France
| | - Jean-Pierre de Villartay
- Laboratory of Genome Dynamics in the Immune System, Laboratoire labellisé Ligue Naionale contre le Cancer, INSERM UMR 1163, Université de Paris, Imagine Institute, Paris, France
| | - Vincent Géli
- U1068 INSERM, Unité Mixte de Recherche (UMR) 7258 (CNRS), Equipe Labellisée Ligue Nationale Contre le Cancer, Marseille Cancer Research Center (CRCM), Institut Paoli-Calmettes, Aix Marseille University, Marseille, France
| | - Yehuda Tzfati
- Department of Genetics, The Silberman Institute of Life Science, The Hebrew University of Jerusalem, Safra Campus-Givat Ram, Jerusalem, Israel
| | - Isabelle Callebaut
- UMR CNRS 7590, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), Muséum National d'Histoire Naturelle, Sorbonne Université, Paris, France
| | - Silvia Danielian
- Department of Immunology, JP Garrahan National Hospital of Pediatrics, Buenos Aires, Argentina
| | - Gabriela Soares
- Centro de Genética Médica Jacinto de Magalhães, Centro Hospitalar e Universitário do Porto, Porto, Portugal
| | - Caroline Kannengiesser
- Service de Génétique, Assistance Publique des Hôpitaux de Paris, Hôpital Bichat, Université Paris Diderot, Paris, France
| | - Patrick Revy
- Laboratory of Genome Dynamics in the Immune System, Laboratoire labellisé Ligue Naionale contre le Cancer, INSERM UMR 1163, Université de Paris, Imagine Institute, Paris, France
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7
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Kumar N, Ghosh M, Manikandan P, Basak S, Deepa A, Singh M. Resonance assignment and secondary structure of the tandem harmonin homology domains of human RTEL1. Biomol NMR Assign 2022; 16:159-164. [PMID: 35320499 DOI: 10.1007/s12104-022-10074-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 02/24/2022] [Indexed: 06/14/2023]
Abstract
Regulator of telomere elongation helicase 1 (RTEL1) is an Fe-S cluster containing DNA helicase that plays important roles in telomere DNA maintenance, DNA repair, and genomic stability. It is a modular protein comprising an N-terminal helicase domain, two tandem harmonin homology domains 1 & 2 (HHD1 and HHD2), and a C-terminal C4C4 type RING domain. The N-terminal helicase domain disassembles the telomere t/D-loop and unwinds the G-quadruplex via its helicase activity. The C-terminal RING domain interacts with telomere DNA binding protein TRF2 and helps RTEL1 recruitment to the telomere. The tandem HHD1 and HHD2 are characterized as a putative protein-protein interaction domain and have recently been shown to interact with a DNA repair protein SLX4. Several mutations associated with Hoyeraal-Hreidarsson syndrome and pulmonary fibrosis have been found in HHD1 and HHD2 of RTEL1. However, these domains have not been characterized for their structures. We have expressed and purified HHD1 and HHD2 of human RTEL1 for their characterization using solution NMR spectroscopy. Here, we report near complete backbone and sidechain 1H, 13C and 15N chemical shift assignments and secondary structure of the HHD1 and HHD2 domains of human RTEL1.
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Affiliation(s)
- Niranjan Kumar
- Molecular Biophysics Unit, Indian Institute of Science, Bengaluru, 560012, India
| | - Meenakshi Ghosh
- Molecular Biophysics Unit, Indian Institute of Science, Bengaluru, 560012, India
| | | | - Sanmoyee Basak
- Molecular Biophysics Unit, Indian Institute of Science, Bengaluru, 560012, India
| | - Akula Deepa
- Molecular Biophysics Unit, Indian Institute of Science, Bengaluru, 560012, India
- Indian Institute of Technology, Hyderabad, 502285, India
| | - Mahavir Singh
- Molecular Biophysics Unit, Indian Institute of Science, Bengaluru, 560012, India.
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8
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Benyelles M, Episkopou H, O'Donohue M, Kermasson L, Frange P, Poulain F, Burcu Belen F, Polat M, Bole‐Feysot C, Langa‐Vives F, Gleizes P, de Villartay J, Callebaut I, Decottignies A, Revy P. Impaired telomere integrity and rRNA biogenesis in PARN-deficient patients and knock-out models. EMBO Mol Med 2019; 11:e10201. [PMID: 31273937 PMCID: PMC6609912 DOI: 10.15252/emmm.201810201] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 04/24/2019] [Accepted: 05/09/2019] [Indexed: 12/12/2022] Open
Abstract
PARN, poly(A)-specific ribonuclease, regulates the turnover of mRNAs and the maturation and stabilization of the hTR RNA component of telomerase. Biallelic PARN mutations were associated with Høyeraal-Hreidarsson (HH) syndrome, a rare telomere biology disorder that, because of its severity, is likely not exclusively due to hTR down-regulation. Whether PARN deficiency was affecting the expression of telomere-related genes was still unclear. Using cells from two unrelated HH individuals carrying novel PARN mutations and a human PARN knock-out (KO) cell line with inducible PARN complementation, we found that PARN deficiency affects both telomere length and stability and down-regulates the expression of TRF1, TRF2, TPP1, RAP1, and POT1 shelterin transcripts. Down-regulation of dyskerin-encoding DKC1 mRNA was also observed and found to result from p53 activation in PARN-deficient cells. We further showed that PARN deficiency compromises ribosomal RNA biogenesis in patients' fibroblasts and cells from heterozygous Parn KO mice. Homozygous Parn KO however resulted in early embryonic lethality that was not overcome by p53 KO. Our results refine our knowledge on the pleiotropic cellular consequences of PARN deficiency.
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Affiliation(s)
- Maname Benyelles
- Laboratory of Genome Dynamics in the Immune SystemINSERM, UMR 1163ParisFrance
- Laboratoire labellisé LigueImagine InstituteParis Descartes–Sorbonne Paris Cite UniversityParisFrance
| | | | - Marie‐Françoise O'Donohue
- Laboratoire de Biologie Moléculaire EucaryoteCentre de Biologie Intégrative (CBI)CNRS, UPSUniversité de ToulouseToulouseFrance
| | - Laëtitia Kermasson
- Laboratory of Genome Dynamics in the Immune SystemINSERM, UMR 1163ParisFrance
- Laboratoire labellisé LigueImagine InstituteParis Descartes–Sorbonne Paris Cite UniversityParisFrance
| | - Pierre Frange
- EA 7327, Université Paris Descartes, Sorbonne Paris‐CitéParisFrance
- Laboratoire de Microbiologie clinique & Unité d'ImmunologieHématologie et Rhumatologie PédiatriquesAP‐HP, Hôpital Necker, Enfants MaladesParisFrance
| | - Florian Poulain
- de Duve InstituteUniversité catholique de LouvainBrusselsBelgium
| | - Fatma Burcu Belen
- Pediatric HematologyFaculty of MedicineBaskent UniversityAnkaraTurkey
| | - Meltem Polat
- Pediatric Infectious DiseasesDepartment of Pediatric Infectious DiseasesPamukkale University Medical FacultyDenizliTurkey
| | - Christine Bole‐Feysot
- INSERM, UMR 1163Genomics platform, Imagine InstituteParis Descartes–Sorbonne Paris Cité UniversityParisFrance
- Genomic Core FacilityImagine Institute‐Structure Fédérative de Recherche NeckerINSERM U1163ParisFrance
| | | | - Pierre‐Emmanuel Gleizes
- Laboratoire de Biologie Moléculaire EucaryoteCentre de Biologie Intégrative (CBI)CNRS, UPSUniversité de ToulouseToulouseFrance
| | - Jean‐Pierre de Villartay
- Laboratory of Genome Dynamics in the Immune SystemINSERM, UMR 1163ParisFrance
- Laboratoire labellisé LigueImagine InstituteParis Descartes–Sorbonne Paris Cite UniversityParisFrance
| | - Isabelle Callebaut
- Muséum National d'Histoire NaturelleUMR CNRS 7590Institut de Minéralogiede Physique des Matériaux et de Cosmochimie, IMPMCSorbonne UniversitéParisFrance
| | | | - Patrick Revy
- Laboratory of Genome Dynamics in the Immune SystemINSERM, UMR 1163ParisFrance
- Laboratoire labellisé LigueImagine InstituteParis Descartes–Sorbonne Paris Cite UniversityParisFrance
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9
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Abstract
Dyskeratosis congenita (DC) is a rare, inherited bone marrow failure (BMF) syndrome characterized by variable manifestations and ages of onset, and predisposition to cancer. DC is one of a spectrum of diseases caused by mutations in genes regulating telomere maintenance, collectively referred to as telomere biology disorders (TBDs). Hematologic disease is common in children with DC/TBD. Timely diagnosis of underlying TBD in patients with BMF affects treatment and has been facilitated by increased awareness and availability of diagnostic tests in recent years. This article summarizes the pathophysiology, evaluation, and management of hematopoietic failure in patients with DC and other TBDs.
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Affiliation(s)
- Suneet Agarwal
- Division of Hematology/Oncology, Harvard Medical School, Dana-Farber Boston Children's Cancer and Blood Disorders Center, Boston Children's Hospital, 1 Blackfan Circle, Karp 07214, Boston, MA 02115, USA.
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10
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Abstract
Mammalian chromosomes terminate in stretches of repetitive telomeric DNA that act as buffers to avoid loss of essential genetic information during end-replication. A multiprotein complex known as shelterin prevents recognition of telomeric sequences as sites of DNA damage. Telomere erosion contributes to human diseases ranging from BM failure to premature aging syndromes and cancer. The role of shelterin telomere protection is less understood. Mutations in genes encoding the shelterin proteins TRF1-interacting nuclear factor 2 (TIN2) and adrenocortical dysplasia homolog (ACD) were identified in dyskeratosis congenita, a syndrome characterized by somatic stem cell dysfunction in multiple organs leading to BM failure and other pleiotropic manifestations. Here, we introduce the biochemical features and in vivo effects of individual shelterin proteins, discuss shelterin functions in hematopoiesis, and review emerging knowledge implicating the shelterin complex in hematological disorders.
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11
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Pereboeva L, Hubbard M, Goldman FD, Westin ER. Robust DNA Damage Response and Elevated Reactive Oxygen Species in TINF2-Mutated Dyskeratosis Congenita Cells. PLoS One 2016; 11:e0148793. [PMID: 26859482 PMCID: PMC4747510 DOI: 10.1371/journal.pone.0148793] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 01/22/2016] [Indexed: 12/13/2022] Open
Abstract
Dyskeratosis Congenita (DC) is an inherited multisystem premature aging disorder with characteristic skin and mucosal findings as well as a predisposition to cancer and bone marrow failure. DC arises due to gene mutations associated with the telomerase complex or telomere maintenance, resulting in critically shortened telomeres. The pathogenesis of DC, as well as several congenital bone marrow failure (BMF) syndromes, converges on the DNA damage response (DDR) pathway and subsequent elevation of reactive oxygen species (ROS). Historically, DC patients have had poor outcomes following bone marrow transplantation (BMT), perhaps as a consequence of an underlying DNA hypersensitivity to cytotoxic agents. Previously, we demonstrated an activated DDR and increased ROS, augmented by chemotherapy and radiation, in somatic cells isolated from DC patients with a mutation in the RNA component of telomerase, TERC. The current study was undertaken to determine whether previous findings related to ROS and DDR in TERC patients’ cells could be extended to other DC mutations. Of particular interest was whether an antioxidant approach could counter increased ROS and decrease DC pathologies. To test this, we examined lymphocytes from DC patients from different DC mutations (TERT, TINF2, and TERC) for the presence of an active DDR and increased ROS. All DC mutations led to increased steady-state p53 (2-fold to 10-fold) and ROS (1.5-fold to 2-fold). Upon exposure to ionizing radiation (XRT), DC cells increased in both DDR and ROS to a significant degree. Exposing DC cells to hydrogen peroxide also revealed that DC cells maintain a significant oxidant burden compared to controls (1.5-fold to 3-fold). DC cell culture supplemented with N-acetylcysteine, or alternatively grown in low oxygen, afforded significant proliferative benefits (proliferation: maximum 2-fold increase; NAC: 5-fold p53 decrease; low oxygen: maximum 3.5-fold p53 decrease). Together, our data supports a mechanism whereby telomerase deficiency and subsequent shortened telomeres initiate a DDR and create a pro-oxidant environment, especially in cells carrying the TINF2 mutations. Finally, the ameliorative effects of antioxidants in vitro suggest this could translate to therapeutic benefits in DC patients.
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Affiliation(s)
- Larisa Pereboeva
- Department of Medicine, Division of Hematology Oncology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Meredith Hubbard
- Department of Pediatrics, Division of Hematology Oncology, University of Alabama, Birmingham, Alabama, United States of America
| | - Frederick D. Goldman
- Department of Pediatrics, Division of Hematology Oncology, University of Alabama, Birmingham, Alabama, United States of America
| | - Erik R. Westin
- Department of Pediatrics, Division of Hematology Oncology, University of Alabama, Birmingham, Alabama, United States of America
- * E-mail:
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12
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13
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Abstract
Human dyskerin is an evolutively conserved protein that participates in diverse nuclear complexes: the H/ACA snoRNPs, that control ribosome biogenesis, RNA pseudouridylation, and stability of H/ACA snoRNAs; the scaRNPs, that control pseudouridylation of snRNAs; and the telomerase active holoenzyme, which safeguards telomere integrity. The biological importance of dyskerin is further outlined by the fact that its deficiency causes the X-linked dyskeratosis congenita disease, while its over-expression characterizes several types of cancers and has been proposed as prognostic marker. The role of dyskerin in telomere maintenance has widely been discussed, while its functions as H/ACA sno/scaRNP component has been so far mostly overlooked and represent the main goal of this review. Here we summarize how increasing evidence indicates that the snoRNA/microRNA pathways can be interlaced, and that dyskerin-dependent RNA pseudouridylation represents a flexible mechanism able to modulate RNA function in different ways, including modulation of splicing, change of mRNA coding properties, and selective regulation of IRES-dependent translation. We also propose a speculative model that suggests that the dynamics of pre-assembly and nuclear import of H/ACA RNPs are crucial regulatory steps that can be finely controlled in the cytoplasm in response to developmental, differentiative and stress stimuli.
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14
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Gutierrez-Rodrigues F, Santana-Lemos BA, Scheucher PS, Alves-Paiva RM, Calado RT. Direct comparison of flow-FISH and qPCR as diagnostic tests for telomere length measurement in humans. PLoS One 2014; 9:e113747. [PMID: 25409313 PMCID: PMC4237503 DOI: 10.1371/journal.pone.0113747] [Citation(s) in RCA: 111] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Accepted: 10/28/2014] [Indexed: 01/11/2023] Open
Abstract
Telomere length measurement is an essential test for the diagnosis of telomeropathies, which are caused by excessive telomere erosion. Commonly used methods are terminal restriction fragment (TRF) analysis by Southern blot, fluorescence in situ hybridization coupled with flow cytometry (flow-FISH), and quantitative PCR (qPCR). Although these methods have been used in the clinic, they have not been comprehensively compared. Here, we directly compared the performance of flow-FISH and qPCR to measure leukocytes' telomere length of healthy individuals and patients evaluated for telomeropathies, using TRF as standard. TRF and flow-FISH showed good agreement and correlation in the analysis of healthy subjects (R2 = 0.60; p<0.0001) and patients (R2 = 0.51; p<0.0001). In contrast, the comparison between TRF and qPCR yielded modest correlation for the analysis of samples of healthy individuals (R2 = 0.35; p<0.0001) and low correlation for patients (R2 = 0.20; p = 0.001); Bland-Altman analysis showed poor agreement between the two methods for both patients and controls. Quantitative PCR and flow-FISH modestly correlated in the analysis of healthy individuals (R2 = 0.33; p<0.0001) and did not correlate in the comparison of patients' samples (R2 = 0.1, p = 0.08). Intra-assay coefficient of variation (CV) was similar for flow-FISH (10.8±7.1%) and qPCR (9.5±7.4%; p = 0.35), but the inter-assay CV was lower for flow-FISH (9.6±7.6% vs. 16±19.5%; p = 0.02). Bland-Altman analysis indicated that flow-FISH was more precise and reproducible than qPCR. Flow-FISH and qPCR were sensitive (both 100%) and specific (93% and 89%, respectively) to distinguish very short telomeres. However, qPCR sensitivity (40%) and specificity (63%) to detect telomeres below the tenth percentile were lower compared to flow-FISH (80% sensitivity and 85% specificity). In the clinical setting, flow-FISH was more accurate, reproducible, sensitive, and specific in the measurement of human leukocyte's telomere length in comparison to qPCR. In conclusion, flow-FISH appears to be a more appropriate method for diagnostic purposes.
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Affiliation(s)
- Fernanda Gutierrez-Rodrigues
- Department of Internal Medicine, University of São Paulo at Ribeirão Preto School of Medicine, Ribeirão Preto, São Paulo, Brazil
- Center for Cell-based Therapy, São Paulo Research Foundation (FAPESP), Ribeirão Preto, São Paulo, Brazil
| | - Bárbara A. Santana-Lemos
- Department of Internal Medicine, University of São Paulo at Ribeirão Preto School of Medicine, Ribeirão Preto, São Paulo, Brazil
- Center for Cell-based Therapy, São Paulo Research Foundation (FAPESP), Ribeirão Preto, São Paulo, Brazil
| | - Priscila S. Scheucher
- Department of Internal Medicine, University of São Paulo at Ribeirão Preto School of Medicine, Ribeirão Preto, São Paulo, Brazil
- Center for Cell-based Therapy, São Paulo Research Foundation (FAPESP), Ribeirão Preto, São Paulo, Brazil
| | - Raquel M. Alves-Paiva
- Department of Internal Medicine, University of São Paulo at Ribeirão Preto School of Medicine, Ribeirão Preto, São Paulo, Brazil
- Center for Cell-based Therapy, São Paulo Research Foundation (FAPESP), Ribeirão Preto, São Paulo, Brazil
| | - Rodrigo T. Calado
- Department of Internal Medicine, University of São Paulo at Ribeirão Preto School of Medicine, Ribeirão Preto, São Paulo, Brazil
- Center for Cell-based Therapy, São Paulo Research Foundation (FAPESP), Ribeirão Preto, São Paulo, Brazil
- * E-mail:
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15
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Agarwal MB. Telomeres and diseases. J Assoc Physicians India 2014; 62:9-11. [PMID: 25906514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
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16
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Schwartz S, Bernstein DA, Mumbach MR, Jovanovic M, Herbst RH, León-Ricardo BX, Engreitz JM, Guttman M, Satija R, Lander ES, Fink G, Regev A. Transcriptome-wide mapping reveals widespread dynamic-regulated pseudouridylation of ncRNA and mRNA. Cell 2014; 159:148-162. [PMID: 25219674 DOI: 10.1016/j.cell.2014.08.028] [Citation(s) in RCA: 661] [Impact Index Per Article: 66.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 08/21/2014] [Accepted: 08/22/2014] [Indexed: 01/14/2023]
Abstract
Pseudouridine is the most abundant RNA modification, yet except for a few well-studied cases, little is known about the modified positions and their function(s). Here, we develop Ψ-seq for transcriptome-wide quantitative mapping of pseudouridine. We validate Ψ-seq with spike-ins and de novo identification of previously reported positions and discover hundreds of unique sites in human and yeast mRNAs and snoRNAs. Perturbing pseudouridine synthases (PUS) uncovers which pseudouridine synthase modifies each site and their target sequence features. mRNA pseudouridinylation depends on both site-specific and snoRNA-guided pseudouridine synthases. Upon heat shock in yeast, Pus7p-mediated pseudouridylation is induced at >200 sites, and PUS7 deletion decreases the levels of otherwise pseudouridylated mRNA, suggesting a role in enhancing transcript stability. rRNA pseudouridine stoichiometries are conserved but reduced in cells from dyskeratosis congenita patients, where the PUS DKC1 is mutated. Our work identifies an enhanced, transcriptome-wide scope for pseudouridine and methods to dissect its underlying mechanisms and function.
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Affiliation(s)
| | | | | | - Marko Jovanovic
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Rebecca H Herbst
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Department of Systems Biology, Harvard Medical School, Boston, MA 02114, USA
| | - Brian X León-Ricardo
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Department of Biology, University of Puerto Rico, Rio Piedras Campus, San Juan 00931, Puerto Rico
| | - Jesse M Engreitz
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Division of Health Sciences and Technology, MIT, Cambridge, MA 02139, USA
| | - Mitchell Guttman
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Rahul Satija
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Eric S Lander
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Department of Systems Biology, Harvard Medical School, Boston, MA 02114, USA; Department of Biology, MIT, Cambridge, MA 02139, USA
| | - Gerald Fink
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Department of Biology, MIT, Cambridge, MA 02139, USA.
| | - Aviv Regev
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Department of Biology, MIT, Cambridge, MA 02139, USA; Howard Hughes Medical Institute, 4000 Jones Bridge Road, Chevy Chase, MD 20815, USA.
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17
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Manguan-Garcia C, Pintado-Berninches L, Carrillo J, Machado-Pinilla R, Sastre L, Pérez-Quilis C, Esmoris I, Gimeno A, García-Giménez JL, Pallardó FV, Perona R. Expression of the genetic suppressor element 24.2 (GSE24.2) decreases DNA damage and oxidative stress in X-linked dyskeratosis congenita cells. PLoS One 2014; 9:e101424. [PMID: 24987982 PMCID: PMC4079255 DOI: 10.1371/journal.pone.0101424] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Accepted: 06/06/2014] [Indexed: 01/10/2023] Open
Abstract
The predominant X-linked form of Dyskeratosis congenita results from mutations in DKC1, which encodes dyskerin, a protein required for ribosomal RNA modification that is also a component of the telomerase complex. We have previously found that expression of an internal fragment of dyskerin (GSE24.2) rescues telomerase activity in X-linked dyskeratosis congenita (X-DC) patient cells. Here we have found that an increased basal and induced DNA damage response occurred in X-DC cells in comparison with normal cells. DNA damage that is also localized in telomeres results in increased heterochromatin formation and senescence. Expression of a cDNA coding for GSE24.2 rescues both global and telomeric DNA damage. Furthermore, transfection of bacterial purified or a chemically synthesized GSE24.2 peptide is able to rescue basal DNA damage in X-DC cells. We have also observed an increase in oxidative stress in X-DC cells and expression of GSE24.2 was able to diminish it. Altogether our data indicated that supplying GSE24.2, either from a cDNA vector or as a peptide reduces the pathogenic effects of Dkc1 mutations and suggests a novel therapeutic approach.
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Affiliation(s)
- Cristina Manguan-Garcia
- Instituto de Investigaciones Biomédicas CSIC/UAM, Madrid, Spain
- CIBER de Enfermedades Raras, Valencia, Spain
| | | | - Jaime Carrillo
- Instituto de Investigaciones Biomédicas CSIC/UAM, Madrid, Spain
| | - Rosario Machado-Pinilla
- Instituto de Investigaciones Biomédicas CSIC/UAM, Madrid, Spain
- CIBER de Enfermedades Raras, Valencia, Spain
| | - Leandro Sastre
- Instituto de Investigaciones Biomédicas CSIC/UAM, Madrid, Spain
- CIBER de Enfermedades Raras, Valencia, Spain
| | - Carme Pérez-Quilis
- Biomedical Research Institute INCLIVA, Valencia, Spain
- Department of Physiology, Faculty of Medicine and Dentistry, University of Valencia, Valencia, Spain
| | - Isabel Esmoris
- Biomedical Research Institute INCLIVA, Valencia, Spain
- Department of Physiology, Faculty of Medicine and Dentistry, University of Valencia, Valencia, Spain
| | - Amparo Gimeno
- Biomedical Research Institute INCLIVA, Valencia, Spain
- Department of Physiology, Faculty of Medicine and Dentistry, University of Valencia, Valencia, Spain
| | - Jose Luis García-Giménez
- CIBER de Enfermedades Raras, Valencia, Spain
- Biomedical Research Institute INCLIVA, Valencia, Spain
- Department of Physiology, Faculty of Medicine and Dentistry, University of Valencia, Valencia, Spain
| | - Federico V. Pallardó
- CIBER de Enfermedades Raras, Valencia, Spain
- Biomedical Research Institute INCLIVA, Valencia, Spain
- Department of Physiology, Faculty of Medicine and Dentistry, University of Valencia, Valencia, Spain
| | - Rosario Perona
- Instituto de Investigaciones Biomédicas CSIC/UAM, Madrid, Spain
- CIBER de Enfermedades Raras, Valencia, Spain
- * E-mail:
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18
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Abstract
DNA secondary structures that arise during DNA replication, repair, and recombination (3R) must be processed correctly to prevent genetic instability. Regulator of telomere length 1 (RTEL1) is an essential DNA helicase that disassembles a variety of DNA secondary structures to facilitate 3R processes and to maintain telomere integrity. The past few years have witnessed the emergence of RTEL1 variants that confer increased susceptibility to high-grade glioma, astrocytomas, and glioblastomas. Mutations in RTEL1 have also been implicated in Hoyeraal-Hreidarsson syndrome, a severe form of the bone-marrow failure and cancer predisposition disorder, dyskeratosis congenita. We review these recent findings and highlight its crucial link between DNA secondary-structure metabolism and human disease.
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Affiliation(s)
- Jean-Baptiste Vannier
- DNA Damage Response Laboratory, London Research Institute, Cancer Research UK, Clare Hall, South Mimms, EN6 3LD, UK
| | - Grzegorz Sarek
- DNA Damage Response Laboratory, London Research Institute, Cancer Research UK, Clare Hall, South Mimms, EN6 3LD, UK
| | - Simon J Boulton
- DNA Damage Response Laboratory, London Research Institute, Cancer Research UK, Clare Hall, South Mimms, EN6 3LD, UK.
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19
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Abstract
Box H/ACA ribonucleoproteins (RNPs), each consisting of one unique guide RNA and 4 common core proteins, constitute a family of complex enzymes that catalyze, in an RNA-guided manner, the isomerization of uridines to pseudouridines (Ψs) in RNAs, a reaction known as pseudouridylation. Over the years, box H/ACA RNPs have been extensively studied revealing many important aspects of these RNA modifying machines. In this review, we focus on the composition, structure, and biogenesis of H/ACA RNPs. We explain the mechanism of how this enzyme family recognizes and specifies its target uridine in a substrate RNA. We discuss the substrates of box H/ACA RNPs, focusing on rRNA (rRNA) and spliceosomal small nuclear RNA (snRNA). We describe the modification product Ψ and its contribution to RNA function. Finally, we consider possible mechanisms of the bone marrow failure syndrome dyskeratosis congenita and of prostate and other cancers linked to mutations in H/ACA RNPs.
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Key Words
- DC, dyskeratosis congenita
- H/ACA
- HH, hoyeraal-hreidarsson syndrome
- PIKK, phosphatidylinositol 3-kinase-related kinase
- PUA, pseudouridylase and archaeosine transglycosylase
- RNA modification
- RNA-guided
- RNP, ribonucleoprotein
- SMN, survival of motor neuron protein
- SSD, SHQ1 specific domain
- U, uridine
- X-DC, X-linked dyskeratosis congenita
- dyskeratosis congenita
- prostate cancer
- pseudouridine
- rRNA
- rRNA, ribosomal RNA
- ribonucleoproteins
- sca, small Cajal body
- snRNA, small nuclear RNA
- sno, small nucleolar
- snoRNA
- snoRNA, small nucleolar RNA
- spliceosomal small nuclear RNA
- tRNA, transfer RNA
- ψ, pseudouridine, 5-ribosyluracil
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MESH Headings
- Dyskeratosis Congenita/genetics
- Dyskeratosis Congenita/metabolism
- Dyskeratosis Congenita/pathology
- Humans
- Isomerism
- Male
- Mutation
- Nucleic Acid Conformation
- Prostatic Neoplasms/genetics
- Prostatic Neoplasms/metabolism
- Prostatic Neoplasms/pathology
- Pseudouridine/metabolism
- RNA Processing, Post-Transcriptional
- RNA, Ribosomal/genetics
- RNA, Ribosomal/metabolism
- RNA, Small Nuclear/genetics
- RNA, Small Nuclear/metabolism
- RNA, Transfer, Amino Acid-Specific/genetics
- RNA, Transfer, Amino Acid-Specific/metabolism
- Ribonucleoproteins, Small Nuclear/genetics
- Ribonucleoproteins, Small Nuclear/metabolism
- Uridine/metabolism
- RNA, Guide, CRISPR-Cas Systems
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Affiliation(s)
- Yi-Tao Yu
- University of Rochester Medical Center; Department of Biochemistry and Biophysics; Center for RNA Biology; Rochester, NY USA
| | - U Thomas Meier
- Albert Einstein College of Medicine; Department of Anatomy and Structural Biology; Bronx, NY USA
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20
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Pereboeva L, Westin E, Patel T, Flaniken I, Lamb L, Klingelhutz A, Goldman F. DNA damage responses and oxidative stress in dyskeratosis congenita. PLoS One 2013; 8:e76473. [PMID: 24124565 PMCID: PMC3790691 DOI: 10.1371/journal.pone.0076473] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Accepted: 08/27/2013] [Indexed: 12/23/2022] Open
Abstract
Dyskeratosis congenita (DC) is an inherited multisystem disorder of premature aging, cancer predisposition, and bone marrow failure caused by selective exhaustion of highly proliferative cell pools. DC patients also have a poor tolerance to chemo/radiotherapy and bone marrow transplantation. Although critically shortened telomeres and defective telomere maintenance contribute to DC pathology, other mechanisms likely exist. We investigate the link between telomere dysfunction and oxidative and DNA damage response pathways and assess the effects of antioxidants. In vitro studies employed T lymphocytes from DC subjects with a hTERC mutation and age-matched controls. Cells were treated with cytotoxic agents, including Paclitaxel, Etoposide, or ionizing radiation. Apoptosis and reactive oxygen species (ROS) were assessed by flow cytometry, and Western blotting was used to measure expression of DNA damage response (DDR) proteins, including total p53, p53S15, and p21(WAF). N-acetyl-cysteine (NAC), an antioxidant, was used to modulate cell growth and ROS. In stimulated culture, DC lymphocytes displayed a stressed phenotype, characterized by elevated levels of ROS, DDR and apoptotic markers as well as a proliferative defect that was more pronounced after exposure to cytotoxic agents. NAC partially ameliorated the growth disadvantage of DC cells and decreased radiation-induced apoptosis and oxidative stress. These findings suggest that oxidative stress may play a role in the pathogenesis of DC and that pharmacologic intervention to correct this pro-oxidant imbalance may prove useful in the clinical setting, potentially alleviating untoward toxicities associated with current cytotoxic treatments.
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Affiliation(s)
- Larisa Pereboeva
- Department of Medicine, Division of Hematology Oncology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Erik Westin
- Department of Pediatrics, Division of Hematology Oncology, Children's Hospital of Alabama, Birmingham, Alabama, United States of America
| | - Toral Patel
- Department of Pediatrics, Division of Hematology Oncology, Children's Hospital of Alabama, Birmingham, Alabama, United States of America
| | - Ian Flaniken
- Department of Pediatrics, Division of Hematology Oncology, Children's Hospital of Alabama, Birmingham, Alabama, United States of America
| | - Lawrence Lamb
- Department of Medicine, Division of Hematology Oncology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Aloysius Klingelhutz
- Department of Microbiology, University of Iowa, Iowa City, Iowa, United States of America
| | - Frederick Goldman
- Department of Pediatrics, Division of Hematology Oncology, Children's Hospital of Alabama, Birmingham, Alabama, United States of America
- * E-mail:
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21
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Machado-Pinilla R, Carrillo J, Manguan-Garcia C, Sastre L, Mentzer A, Gu BW, Mason PJ, Perona R. Defects in mTR stability and telomerase activity produced by the Dkc1 A353V mutation in dyskeratosis congenita are rescued by a peptide from the dyskerin TruB domain. Clin Transl Oncol 2012; 14:755-63. [PMID: 22855157 DOI: 10.1007/s12094-012-0865-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2011] [Accepted: 12/16/2011] [Indexed: 12/15/2022]
Abstract
BACKGROUND The predominant X-linked form of dyskeratosis congenita results from mutations in dyskerin, a protein required for ribosomal RNA modification that is also a component of the telomerase complex. We have previously found that expression of an internal fragment of dyskerin (GSE24.2) rescues telomerase activity in X-linked dyskeratosis congenita (X-DC) patient cells. MATERIALS AND METHODS Here, we have generated F9 mouse cell lines expressing the most frequent mutation found in X-DC patients, A353V and study the effect of expressing the GSE24.2 cDNA or GSE24.2 peptide on telomerase activity by TRAP assay, and mTERT and mTR expression by Q-PCR. Point mutation in GSE24.2 residues were generated by site-directed mutagenesis. RESULTS Expression of GSE24.2 increases mTR and to a lesser extent mTERT RNA levels, and leads to recovery of telomerase activity. Point mutations in GSE24.2 residues known to be highly conserved and crucial for the pseudouridine-synthase activity of dyskerin abolished the effect of the peptide. Recovery of telomerase activity and increase in mTERT levels were found when the GSE24.2 peptide purified from bacteria was introduced into the cells. Moreover, mTR stability was also rescued by transfection of the peptide GSE24.2. DISCUSSION These data indicate that supplying GSE24.2, either from a cDNA vector, or as a peptide, can reduces the pathogenic effects of Dkc1 mutations and could form the basis of a novel therapeutic approach.
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22
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Abstract
The regulation of telomere length (TL) is a complex process, requiring the telomerase enzyme complex and numerous regulatory proteins. Epigenetic regulation may also be important in telomere maintenance. Specifically, methylation at subtelomeres is associated with changes in TL in vitro and in mouse models. Dyskeratosis congenita (DC) is an inherited bone marrow failure syndrome characterized by exceedingly short telomeres and mutations in telomere biology genes. To understand the interaction between methylation and TL in humans, we measured LINE-1, pericentromeric (NBL2), and subtelomeric (D4Z4) methylation in peripheral blood DNA derived from 40 patients with DC and 51 mutation-negative relatives. Pearson's correlation coefficient and linear regression models were used to evaluate the relationship between age-standardized lymphocyte TL measured by flow FISH and % DNA methylation. No differences in % subtelomeric, LINE-1, or pericentromeric methylation between patients with DC and relatives were noted except for an increase in % subtelomeric methylation in DC patients with a telomerase-complex mutation (TERC, TERT, DKC1, or TCAB1) (63.0% in DC vs. 61.8% in relatives, P = 0.03). Positive correlations between TL and DNA methylation at LINE-1 (r = 0.39, P = 0.01) and subtelomeric (r = 0.32, P = 0.05) sites were present in patients with DC. The positive correlation between TL and % LINE-1 methylation was restricted to TINF2 mutations. In contrast, statistically nonsignificant inverse correlations between TL and % LINE-1 (r = -0.17), subtelomeric (r = -0.20) were present in unaffected relatives. This study suggests an interaction between TL and both subtelomeric and LINE-1 methylation, which may be altered based on mutation status of telomere biology genes.
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Affiliation(s)
- Shahinaz M Gadalla
- Clinical Genetics Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, MD 20852, USA
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23
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Zhang Y, Morimoto K, Danilova N, Zhang B, Lin S. Zebrafish models for dyskeratosis congenita reveal critical roles of p53 activation contributing to hematopoietic defects through RNA processing. PLoS One 2012; 7:e30188. [PMID: 22299032 PMCID: PMC3267717 DOI: 10.1371/journal.pone.0030188] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Accepted: 12/14/2011] [Indexed: 11/19/2022] Open
Abstract
Dyskeratosis congenita (DC) is a rare bone marrow failure syndrome in which hematopoietic defects are the main cause of mortality. The most studied gene responsible for DC pathogenesis is DKC1 while mutations in several other genes encoding components of the H/ACA RNP telomerase complex, which is involved in ribosomal RNA(rRNA) processing and telomere maintenance, have also been implicated. GAR1/nola1 is one of the four core proteins of the H/ACA RNP complex. Through comparative analysis of morpholino oligonucleotide induced knockdown of dkc1 and a retrovirus insertion induced mutation of GAR1/nola1 in zebrafish, we demonstrate that hematopoietic defects are specifically recapitulated in these models and that these defects are significantly reduced in a p53 null mutant background. We further show that changes in telomerase activity are undetectable at the early stages of DC pathogenesis but rRNA processing is clearly defective. Our data therefore support a model that deficiency in dkc1 and nola1 in the H/ACA RNP complex likely contributes to the hematopoietic phenotype through p53 activation associated with rRNA processing defects rather than telomerase deficiency during the initial stage of DC pathogenesis.
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Affiliation(s)
- Ying Zhang
- Laboratory of Chemical Genomics, Shenzhen Graduate School, Peking University, Shenzhen, China
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Yang D, He Q, Kim H, Ma W, Songyang Z. TIN2 protein dyskeratosis congenita missense mutants are defective in association with telomerase. J Biol Chem 2011; 286:23022-30. [PMID: 21536674 PMCID: PMC3123070 DOI: 10.1074/jbc.m111.225870] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2011] [Revised: 04/29/2011] [Indexed: 12/18/2022] Open
Abstract
Dyskeratosis congenita (DC) is a progressive and heterogeneous congenital disorder that affects multiple systems and is characterized by bone marrow failure and a triad of abnormal skin pigmentation, nail dystrophy, and oral leukoplakia. One common feature for all DC patients is abnormally short telomeres and defects in telomere biology. Most of the known DC mutations have been found to affect core components of the telomerase holoenzyme. Recently, multiple mutations in the gene encoding the telomeric protein TIN2 have been identified in DC patients with intact telomerase genes, but the molecular mechanisms underlying TIN2 mutation-mediated DC remain unknown. Here, we demonstrate that ectopic expression of TIN2 with DC missense mutations in human cells led to accelerated telomere shortening, similar to the telomere phenotypes found in DC patients. However, this telomere shortening was not accompanied by changes in total telomerase activity, localization of TIN2, or telomere end protection status. Interestingly, we found TIN2 to participate in the TPP1-dependent recruitment of telomerase activity. Furthermore, DC mutations in TIN2 led to its decreased ability to associate with TERC and telomerase activity. Taken together, our data suggest that TIN2 mutations in DC may compromise the telomere recruitment of telomerase, leading to telomere shortening and the associated pathogenesis.
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Affiliation(s)
- Dong Yang
- the Verna and Mars McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030
| | - Quanyuan He
- the Verna and Mars McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030
| | - Hyeung Kim
- the Verna and Mars McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030
| | - Wenbin Ma
- From the State Key Laboratory for Biocontrol, Sun Yat-Sen University, Guangzhou 510275, China and
- the Verna and Mars McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030
| | - Zhou Songyang
- From the State Key Laboratory for Biocontrol, Sun Yat-Sen University, Guangzhou 510275, China and
- the Verna and Mars McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030
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Parry EM, Alder JK, Lee SS, Phillips JA, Loyd JE, Duggal P, Armanios M. Decreased dyskerin levels as a mechanism of telomere shortening in X-linked dyskeratosis congenita. J Med Genet 2011; 48:327-33. [PMID: 21415081 PMCID: PMC3088476 DOI: 10.1136/jmg.2010.085100] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Dyskeratosis congenita (DC) is a premature ageing syndrome characterised by short telomeres. An X-linked form of DC is caused by mutations in DKC1 which encodes dyskerin, a telomerase component that is essential for telomerase RNA stability. However, mutations in DKC1 are identifiable in only half of X-linked DC families. A four generation family with pulmonary fibrosis and features of DC was identified. Affected males showed the classic mucocutaneous features of DC and died prematurely from pulmonary fibrosis. Although there were no coding sequence or splicing variants, genome wide linkage analysis of 16 individuals across four generations identified significant linkage at the DKC1 locus, and was accompanied by reduced dyskerin protein levels in affected males. Decreased dyskerin levels were associated with compromised telomerase RNA levels and very short telomeres. These data identify decreased dyskerin levels as a novel mechanism of DC, and indicate that intact dyskerin levels, in the absence of coding mutations, are critical for telomerase RNA stability and for in vivo telomere maintenance.
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Affiliation(s)
- Erin M Parry
- Department of Oncology and Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine Baltimore, Maryland, USA
- Medical Scientist Training Progra, Johns Hopkins University School of Medicine Baltimore, Maryland, USA
| | - Jonathan K Alder
- Department of Oncology and Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine Baltimore, Maryland, USA
| | - Stella S Lee
- Pre-doctoral Training Program in Human Genetics, Johns Hopkins University School of Medicine Baltimore, Maryland, USA
| | - John A Phillips
- Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - James E Loyd
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Priya Duggal
- Department of Epidemiology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Mary Armanios
- Department of Oncology and Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine Baltimore, Maryland, USA
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine Baltimore, Maryland, USA
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26
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Trahan C, Dragon F. Dyskeratosis congenita mutations in the H/ACA domain of human telomerase RNA affect its assembly into a pre-RNP. RNA 2009; 15:235-243. [PMID: 19095616 PMCID: PMC2648702 DOI: 10.1261/rna.1354009] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2008] [Accepted: 10/30/2008] [Indexed: 05/27/2023]
Abstract
Dyskeratosis congenita (DC) is an inherited disorder that implicates defects in the biology of telomeres, which are maintained by telomerase, a ribonucleoprotein with reverse transcriptase activity. Like all H/ACA RNAs, the H/ACA domain of nascent human telomerase RNA (hTR) forms a pre-RNP with H/ACA proteins NAF1, dyskerin, NOP10, and NHP2 in vivo. To assess the pre-RNP assembly of hTR mutants that poorly accumulate in vivo, we developed an in vitro system that uses components of human origin. Pre-RNPs were reconstituted with synthetic (32)P-labeled RNAs and (35)S-labeled proteins produced in rabbit reticulocyte lysate, and immunoprecipitations were carried out to analyze RNP formation. We show that human NAF1 cannot bind directly to the H/ACA domain of hTR, and requires the core trimer dyskerin-NOP10-NHP2 to be efficiently incorporated into the pre-RNP. This order of assembly seems common to H/ACA RNAs since it was observed with snoRNA ACA36 and scaRNA U92, which are predicted to guide pseudouridylation of 18S rRNA and U2 snRNA, respectively. However, the processing H/ACA snoRNA U17 did not conform to this rule, as NAF1 alone was able to bind it. We also provide the first evidence that DC-related mutations of hTR C408G and Delta378-451 severely impair pre-RNP assembly. Integrity of boxes H and ACA of hTR are also crucial for pre-RNP assembly, while the CAB box is dispensable. Our results offer new insights into the defects caused by some mutations located in the H/ACA domain of hTR.
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Affiliation(s)
- Christian Trahan
- Département des Sciences Biologiques and Centre de Recherche BioMed, Université du Québec à Montréal, Canada
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27
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Du HY, Pumbo E, Ivanovich J, An P, Maziarz RT, Reiss UM, Chirnomas D, Shimamura A, Vlachos A, Lipton JM, Goyal RK, Goldman F, Wilson DB, Mason PJ, Bessler M. TERC and TERT gene mutations in patients with bone marrow failure and the significance of telomere length measurements. Blood 2009; 113:309-16. [PMID: 18931339 PMCID: PMC2615648 DOI: 10.1182/blood-2008-07-166421] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2008] [Accepted: 09/21/2008] [Indexed: 12/30/2022] Open
Abstract
Dyskeratosis congenita (DC) is a rare inherited form of bone marrow failure (BMF) caused by mutations in telomere maintaining genes including TERC and TERT. Here we studied the prevalence of TERC and TERT gene mutations and of telomere shortening in an unselected population of patients with BMF at our medical center and in a selected group of patients referred from outside institutions. Less than 5% of patients with BMF had pathogenic mutations in TERC or TERT. In patients with BMF, pathogenic TERC or TERT gene mutations were invariably associated with marked telomere shortening (<< 1st percentile) in peripheral blood mononuclear cells (PBMCs). In asymptomatic family members, however, telomere length was not a reliable predictor for the presence or absence of a TERC or TERT gene mutation. Telomere shortening was not pathognomonic of DC, as approximately 30% of patients with BMF due to other causes had PBMC telomere lengths at the 1st percentile or lower. We conclude that in the setting of BMF, measurement of telomere length is a sensitive but nonspecific screening method for DC. In the absence of BMF, telomere length measurements should be interpreted with caution.
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Affiliation(s)
- Hong-Yan Du
- Department of Internal Medicine, Washington University School of Medicine, St Louis, MO 63110, USA
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28
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Abstract
The H/ACA RNAs are an abundant family of trans-acting, noncoding RNAs found in eukaryotes and archaea. More than 100 H/ACA RNAs are known to exist in humans. The function of the majority of the identified H/ACA RNAs is to guide sites-pecific pseudouridylation of ribosomal RNA. In eukaryotes, H/ACA RNAs also mediate the processing of pre-rRNA, provide the template for telomere synthesis, and guide pseudouridylation of other classes of target RNAs (e.g., small nuclear RNAs [snRNAs]). Thus, currently, the H/ACA RNAs are known to be integrally involved in the production of both ribosomes and spliceosomes, and in the maintenance of chromosome integrity. In addition, dozens of H/ACA RNAs have been identified for which no function has yet been determined. The H/ACA RNAs select and present substrate molecules via base pairing. All H/ACA RNAs contain conserved sequence elements (box H and box ACA) and assemble with a core set of four proteins to form functional ribonucleoprotein complexes (RNPs). Mutations in key RNA and protein components of H/ACA RNPs result in dyskeratosis congenita, a serious multisystem genetic disease. Impressive progress has been made very recently in understanding the biogenesis, trafficking, and function of H/ACA RNPs.
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Affiliation(s)
- M Terns
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602, USA
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Westin ER, Chavez E, Lee KM, Gourronc FA, Riley S, Lansdorp PM, Goldman FD, Klingelhutz AJ. Telomere restoration and extension of proliferative lifespan in dyskeratosis congenita fibroblasts. Aging Cell 2007; 6:383-94. [PMID: 17381549 PMCID: PMC2225626 DOI: 10.1111/j.1474-9726.2007.00288.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Dyskeratosis congenita (DC), an inherited bone marrow failure syndrome, is caused by defects in telomerase. Somatic cells from DC patients have shortened telomeres and clinical symptoms are most pronounced in organs with a high cell turnover, including those involved in hematopoiesis and skin function. We previously identified an autosomal dominant (AD) form of DC that is caused by mutations in the telomerase RNA component (TER). In this study, we evaluated whether retroviral expression of TER and/or telomerase reverse transcriptase (TERT), the catalytic component of telomerase, could extend telomere length and rescue AD DC cells from a phenotype characteristic of early senescence. Exogenous TER expression, without TERT, could not activate telomerase in AD DC skin fibroblasts. Transduction of TERT alone, however, provided AD DC cells with sufficient telomerase activity to extend average telomere length and proliferative capacity. Interestingly, we found that expression of TER and TERT together resulted in extension of lifespan and higher levels of telomerase and longer telomeres than expression of TERT alone in both AD DC and normal cells. Our results provide evidence that AD DC cells can be rescued from defects in telomere maintenance and proliferation, and that coexpression of TERT and TER together provides a more efficient means to elongate telomeres than expression of TERT alone. Similar strategies may be useful for ameliorating the detrimental effects of telomere shortening in AD DC and other diseases associated with telomerase or telomere defects.
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Affiliation(s)
- Erik R. Westin
- Interdisciplinary Program in Genetics, University of Iowa, Iowa City, IA, USA
| | - Elizabeth Chavez
- Terry Fox Laboratory, British Columbia Cancer Agency, Vancouver, British Columbia, Canada
| | - Kimberly M. Lee
- Department of Microbiology, University of Iowa, Iowa City, IA, USA
| | | | - Soraya Riley
- Program in Molecular and Cellular Biology, University of Iowa, Iowa City, IA, USA
| | - Peter M. Lansdorp
- Terry Fox Laboratory, British Columbia Cancer Agency, Vancouver, British Columbia, Canada
- Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
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30
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Abstract
More than 100 mammalian H/ACA RNAs form an equal number of ribonucleoproteins (RNPs) by associating with the same four core proteins. The function of these H/ACA RNPs is essential for biogenesis of the ribosome, splicing of precursor mRNAs (pre-mRNAs), maintenance of telomeres and probably for additional cellular processes. Recent crystal structures of archaeal H/ACA protein complexes show how the same four proteins accommodate >100 distinct but related H/ACA RNAs and reveal that a spatial mutation cluster underlies dyskeratosis congenita, a syndrome of bone marrow failure.
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Affiliation(s)
- U Thomas Meier
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA.
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31
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Rashid R, Liang B, Baker DL, Youssef OA, He Y, Phipps K, Terns RM, Terns MP, Li H. Crystal structure of a Cbf5-Nop10-Gar1 complex and implications in RNA-guided pseudouridylation and dyskeratosis congenita. Mol Cell 2006; 21:249-60. [PMID: 16427014 DOI: 10.1016/j.molcel.2005.11.017] [Citation(s) in RCA: 135] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2005] [Revised: 11/02/2005] [Accepted: 11/15/2005] [Indexed: 11/20/2022]
Abstract
H/ACA RNA-protein complexes, comprised of four proteins and an H/ACA guide RNA, modify ribosomal and small nuclear RNAs. The H/ACA proteins are also essential components of telomerase in mammals. Cbf5 is the H/ACA protein that catalyzes isomerization of uridine to pseudouridine in target RNAs. Mutations in human Cbf5 (dyskerin) lead to dyskeratosis congenita. Here, we describe the 2.1 A crystal structure of a specific complex of three archaeal H/ACA proteins, Cbf5, Nop10, and Gar1. Cbf5 displays structural properties that are unique among known pseudouridine synthases and are consistent with its distinct function in RNA-guided pseudouridylation. We also describe the previously unknown structures of both Nop10 and Gar1 and the structural basis for their essential roles in pseudouridylation. By using information from related structures, we have modeled the entire ribonucleoprotein complex including both guide and substrate RNAs. We have also identified a dyskeratosis congenita mutation cluster site within a modeled dyskerin structure.
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Affiliation(s)
- Rumana Rashid
- Department of Chemistry and Biochemistry, Institute of Molecular Biophysics, Florida State University, Tallahassee, Florida 32306, USA
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32
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Abstract
Dyskeratosis congenita (DC) is a rare multisystem bone marrow failure syndrome that displays marked clinical and genetic heterogeneity. X-linked recessive, autosomal dominant and autosomal recessive forms of the disease are recognized. The gene that is mutated in the X-linked form of the disease is DKC1. The DKC1-encoded protein, dyskerin, is a component of small nucleolar ribonucleoprotein particles, which are important in ribosomal RNA processing, and of the telomerase complex. The autosomal dominant form of DC is due to mutations in the gene for the RNA component of telomerase (TERC). Because both dyskerin and TERC are components of the telomerase complex and all patients with DC have short telomeres, the principal pathology of DC appears to relate to telomerase dysfunction, although defects in ribosomal processing via dyskerin's involvement in pseudouridylation cannot be completely ruled out. The gene or genes involved in autosomal recessive DC remain elusive, although genes whose products are required for telomere maintenance remain strong candidates. The study of DC highlights the importance of telomerase in humans and how its deficiency results in multiple abnormalities, including premature aging, bone marrow failure, and cancer.
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Affiliation(s)
- Amanda J Walne
- Department of Haematology, Division of Investigative Science, Faculty of Medicine, Imperial College London, Hammersmith Hospital, London, United Kingdom.
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34
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Ruggero D, Grisendi S, Piazza F, Rego E, Mari F, Rao PH, Cordon-Cardo C, Pandolfi PP. Dyskeratosis congenita and cancer in mice deficient in ribosomal RNA modification. Science 2003; 299:259-62. [PMID: 12522253 DOI: 10.1126/science.1079447] [Citation(s) in RCA: 342] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Mutations in DKC1 cause dyskeratosis congenita (DC), a disease characterized by premature aging and increased tumor susceptibility. The DKC1 protein binds to the box H + ACA small nucleolar RNAs and the RNA component of telomerase. Here we show that hypomorphic Dkc1 mutant (Dkc1m) mice recapitulate in the first and second generations (G1 and G2) the clinical features of DC. Dkc1m cells from G1 and G2 mice were impaired in ribosomal RNA pseudouridylation before the onset of disease. Reductions of telomere length in Dkc1m mice became evident only in later generations. These results suggest that deregulated ribosome function is important in the initiation of DC, whereas telomere shortening may modify and/or exacerbate DC.
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Affiliation(s)
- Davide Ruggero
- Molecular Biology Program, Department of Pathology, Memorial Sloan-Kettering Cancer Center, Sloan-Kettering Institute, 1275 York Avenue, New York, NY 10021, USA
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35
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Gilmour KC, Cranston T, Jones A, Davies EG, Goldblatt D, Thrasher A, Kinnon C, Nichols KE, Gaspar HB. Diagnosis of X-linked lymphoproliferative disease by analysis of SLAM-associated protein expression. Eur J Immunol 2000; 30:1691-7. [PMID: 10898506 DOI: 10.1002/1521-4141(200006)30:6<1691::aid-immu1691>3.0.co;2-k] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
X-linked lymphoproliferative disease (XLP) is an inherited immunodeficiency in which affected boys show abnormal responses to Epstein-Barr virus infection. The gene defective in XLP has been identified and designated SH2D1A and encodes a protein termed SLAM-associated protein (SAP). Mutation analysis in individuals with typical XLP presentations and family histories has only detected abnormalities in approximately 60% of patients. Thus, genetic analysis alone cannot confirm a diagnosis of XLP We have developed a SAP expression assay that can be used as a diagnostic indicator of XLP We show that SAP is constitutively expressed in normal individuals, in patients with severe sepsis and in patients with other primary immunodeficiencies. In six XLP patients, four with classical and two with atypical presentations, SAP expression was absent. In the latter two, who were previously assigned as having common variable immunodeficiency (CVID), the diagnosis of XLP was initially made using the protein expression assay. In two further patients in whom no mutation could be detected by genetic analysis, lack of SAP expression strongly suggests that these individuals have XLP. We therefore suggest that XLP should be suspected in certain boys previously diagnosed as having CVID and recommend that patients are investigated both by genetic analysis of SH2D1A and by expression of SAP protein.
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Affiliation(s)
- K C Gilmour
- Department of Immunology, Great Ormond Street Hospital NHS Trust, London, GB
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36
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Abstract
As normal humans age, telomeres shorten in tissues that contain dividing cells, and this has been proposed both as a cause of ageing and as a tumor-suppressor mechanism. The surprising finding that cells from individuals with the rare inherited disorder dyskeratosis congenita (DKC) have reduced levels of telomerase and shortened telomeres might provide the first direct genetic test of the function of telomeres in intact humans.
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Affiliation(s)
- R A Marciniak
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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37
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Affiliation(s)
- J W Shay
- University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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Heiss NS, Girod A, Salowsky R, Wiemann S, Pepperkok R, Poustka A. Dyskerin localizes to the nucleolus and its mislocalization is unlikely to play a role in the pathogenesis of dyskeratosis congenita. Hum Mol Genet 1999; 8:2515-24. [PMID: 10556300 DOI: 10.1093/hmg/8.13.2515] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Mutations in the DKC1 gene are responsible for causing the bone marrow failure syndrome, dyskeratosis congenita (DKC; OMIM 305000). The majority of mutations identified to date are missense mutations and are clustered in exons 3, 4 and 11. It is predicted that the corresponding protein dyskerin is a nucleolar phosphoprotein which functions in both pseudo-uridylation and cleavage of precursor rRNA. Dyskerin contains multiple putative nuclear localization signals (NLSs) at the N-terminus (KKHKKKKERKS) and C-terminus [KRKR(X)(17)KKEKKKSKKDKKAK(X)(17)-KKKKKKKKAKEVELVSE]. By fusing dyskerin with the enhanced green fluorescent protein (EGFP) and by following a time course of expression in mammalian cell lines, we showed that full-length dyskerin initially localizes to the nucleoplasm and subsequently accumulates in the nucleoli. A co-localization to the coiled bodies was observed in some cells where dyskerin-EGFP had translocated to the nucleoli. Analysis of a series of mutant constructs indicated that whereas the most C-terminal lysine-rich clusters [KKEKKKS-KKDKKAK(X)(17)KKKKKKKKAKEVELVSE] influence the rate of nucleoplasmic and nucleolar accumulation, the KRKR sequence is primarily responsible for the nuclear import. Nucleolar localization was maintained when either the N- or C-terminal motifs were mutated, but not when all NLSs were removed. We conclude that the intranuclear localization of dyskerin is accomplished by the synergistic effect of a number of NLSs and that the nucleolar localization signals are contained within the NLSs. Further, examination of dyskerin-EGFP fusions mimicking mutations detected in patients indicated that the intracellular mislocalization of dyskerin is unlikely to cause DKC.
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Affiliation(s)
- N S Heiss
- Deutsches Krebsforschungszentrum (DKFZ), Department of Molecular Genome Analysis, Im Neuenheimer Feld 280, D-69120 Heidelberg, Germany
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Youssoufian H, Gharibyan V, Qatanani M. Analysis of epitope-tagged forms of the dyskeratosis congenital protein (dyskerin): identification of a nuclear localization signal. Blood Cells Mol Dis 1999; 25:305-9. [PMID: 10744426 DOI: 10.1006/bcmd.1999.0258] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The X-linked form of the bone marrow failure syndrome Dyskeratosis congenital is caused by mutations in dyskerin, a 514 amino acid protein that is presumed to play a role in ribosome biogenesis. Here we report that dyskerin tagged with the human immunoglobulin epitope localizes to nuclei of transfected HeLa and COS-1 cells. A carboxyl-terminal domain consisting of amino acids 467-475 and encoding KKEKKKSKK is both necessary and sufficient to mediate nuclear entry. Immunoglobulin-tagged dyskerin did not interact with the Fanconi anemia group A protein, FANCA. These results suggest a nuclear role for dyskerin. Moreover, hematopoietic failure observed in both Dyskeratosis congenital and the most common type of Fanconi anemia is unlikely to have a common mechanism resulting from abnormal physical interactions between the respective gene products of these disorders.
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Affiliation(s)
- H Youssoufian
- Department of Molecular and Human Genetics, Baylor College of Medicine.Houston. TX 77030, USA.
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