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Dimitrov M, Merkle S, Cao Q, Tryon RK, Vercellotti GM, Holtan SG, Kao RL, Srikanthan M, Terezakis SA, Tolar J, Ebens CL. Allogeneic Hematopoietic Cell Transplant For Bone Marrow Failure or Myelodysplastic Syndrome in Dyskeratosis Congenita/Telomere Biology Disorders: Single-Center, Single-Arm, Open-Label Trial of Reduced-Intensity Conditioning Without Radiation. Transplant Cell Ther 2024:S2666-6367(24)00530-X. [PMID: 39002862 DOI: 10.1016/j.jtct.2024.07.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Revised: 06/27/2024] [Accepted: 07/03/2024] [Indexed: 07/15/2024]
Abstract
BACKGROUND Dyskeratosis congenita/telomere biology disorders (DC/TBD) often manifest as bone marrow failure (BMF) or myelodysplastic syndrome (MDS). Allogeneic hematopoietic cell transplant (alloHCT) rescues hematologic complications, but radiation and alkylator-based conditioning regimens cause diffuse whole-body toxicity and may expedite DC/TBD-specific non-hematopoietic complications. Optimization of conditioning intensity in DC/TBD to allow for donor hematopoietic cell engraftment with the least amount of toxicity remains a critical goal of the alloHCT field. OBJECTIVES/STUDY DESIGN We report prospectively collected standard alloHCT outcomes from a single-center, single-arm, open-label clinical trial of bone marrow or peripheral blood stem cell alloHCT for DC/TBD-associated BMF or MDS. Conditioning was reduced intensity (RIC), including alemtuzumab 1 mg/kg, fludarabine 200 mg/m2, and cyclophosphamide 50 mg/kg. A previous single-arm, open-label phase II clinical trial for the same patient population conducted at the same center, differing only by inclusion of 200 cGy of total body irradiation (TBI), served as a control cohort. RESULTS The non-TBI cohort included 10 patients (ages 1.7-65.9 years, median follow-up of 3.9 years) compared with the control TBI cohort, which included 12 patients (ages 2.2-52.2 years, median follow-up of 10.5 years). Baseline characteristics differed only in total CD34+ cells received, with a median of 5.6 (non-TBI) compared with 2.6 (TBI) x 106/kg (P = .02; no difference in total nucleated cells). The cumulative incidence of day +100 grade II-IV acute and 4-year chronic graft-versus-host disease (GvHD) were low at 0% and 10% (non-TBI) and 8% and 17% (TBI), respectively (acute, P = .36; chronic, P = .72). Primary graft failure was absent. Secondary non-neutropenic graft failure occurred in one (non-TBI cohort). The non-TBI cohort demonstrated delayed achievement of full donor chimerism but superior lymphocyte recovery. There was no difference in 4-year overall survival at 80% (non-TBI) and 75% (TBI; P = .78). MDS as an indication for alloHCT was uncommon but overall associated with poor outcomes. There were 3 MDS patients in the non-TBI cohort: 1 relapsed and died at day +387; 1 relapsed at day +500 and is alive 5.5 years later following salvage with a second alloHCT; 1 relapsed at day +1093 and is alive at day +100 after a second alloHCT. There was 1 MDS patient in the TBI cohort who achieved 100% donor myeloid engraftment without relapse but died at day +827 from a bacterial infection in the setting of immune-mediated cytopenia. CONCLUSION Elimination of TBI from the RIC regimen for DC/TBD was not associated with significant changes in rates of graft failure, GvHD, and overall survival but was associated with delayed achievement of full donor chimerism and improved lymphocyte reconstitution. For DC/TBD-associated BMF, TBI appears to be dispensable. Optimal approaches to DC/TBD-associated MDS remain unclear. Larger cohorts are needed to better assess the unique contribution of TBI and donor CD34+ cell dose. Longer follow-up is required to assess differences in DC/TBD complications and late effects.
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Affiliation(s)
- Marketa Dimitrov
- Division of Pediatric Hematology/Oncology, University of Minnesota, Minneapolis, Minnesota
| | - Svatava Merkle
- Department of Pediatrics, University of Minnesota, Minneapolis, Minnesota
| | - Qing Cao
- Biostatistics Core, Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota
| | - Rebecca K Tryon
- Department of Genetics, University of Minnesota, Minneapolis, Minnesota
| | - Gregory M Vercellotti
- Division of Hematology, Oncology and Transplantation, University of Minnesota, Minneapolis, Minnesota
| | - Shernan G Holtan
- Division of Hematology, Oncology and Transplantation, University of Minnesota, Minneapolis, Minnesota
| | - Roy L Kao
- Division of Hematology, Oncology and Transplantation, University of Minnesota, Minneapolis, Minnesota
| | - Meera Srikanthan
- Division of Pediatric Blood and Marrow Transplant & Cellular Therapy, Department of Pediatrics, University of Minnesota, Minneapolis, Minnesota
| | | | - Jakub Tolar
- Division of Pediatric Blood and Marrow Transplant & Cellular Therapy, Department of Pediatrics, University of Minnesota, Minneapolis, Minnesota
| | - Christen L Ebens
- Division of Pediatric Blood and Marrow Transplant & Cellular Therapy, Department of Pediatrics, University of Minnesota, Minneapolis, Minnesota.
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Jeong HC, Shukla S, Fok WC, Huynh TN, Batista LFZ, Parker R. USB1 is a miRNA deadenylase that regulates hematopoietic development. Science 2023; 379:901-907. [PMID: 36862787 PMCID: PMC10827040 DOI: 10.1126/science.abj8379] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 02/03/2023] [Indexed: 03/04/2023]
Abstract
Mutations in the 3' to 5' RNA exonuclease USB1 cause hematopoietic failure in poikiloderma with neutropenia (PN). Although USB1 is known to regulate U6 small nuclear RNA maturation, the molecular mechanism underlying PN remains undetermined, as pre-mRNA splicing is unaffected in patients. We generated human embryonic stem cells harboring the PN-associated mutation c.531_delA in USB1 and show that this mutation impairs human hematopoiesis. Dysregulated microRNA (miRNA) levels in USB1 mutants during blood development contribute to hematopoietic failure, because of a failure to remove 3'-end adenylated tails added by PAPD5/7. Modulation of miRNA 3'-end adenylation through genetic or chemical inhibition of PAPD5/7 rescues hematopoiesis in USB1 mutants. This work shows that USB1 acts as a miRNA deadenylase and suggests PAPD5/7 inhibition as a potential therapy for PN.
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Affiliation(s)
- Ho-Chang Jeong
- Division of Hematology, Department of Medicine, Washington University in St. Louis, St. Louis, MO 63110, USA
- Center for Genome Integrity, Siteman Cancer Center, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Siddharth Shukla
- Department of Biochemistry, University of Colorado, Boulder, CO 80303, USA
- Howard Hughes Medical Institute, Chevy Chase MD 20815, USA
| | - Wilson Chun Fok
- Division of Hematology, Department of Medicine, Washington University in St. Louis, St. Louis, MO 63110, USA
- Center for Genome Integrity, Siteman Cancer Center, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Thao Ngoc Huynh
- Department of Biochemistry, University of Colorado, Boulder, CO 80303, USA
- Howard Hughes Medical Institute, Chevy Chase MD 20815, USA
| | - Luis Francisco Zirnberger Batista
- Division of Hematology, Department of Medicine, Washington University in St. Louis, St. Louis, MO 63110, USA
- Center for Genome Integrity, Siteman Cancer Center, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Roy Parker
- Department of Biochemistry, University of Colorado, Boulder, CO 80303, USA
- Howard Hughes Medical Institute, Chevy Chase MD 20815, USA
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3
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Revy P, Kannengiesser C, Bertuch AA. Genetics of human telomere biology disorders. Nat Rev Genet 2023; 24:86-108. [PMID: 36151328 DOI: 10.1038/s41576-022-00527-z] [Citation(s) in RCA: 43] [Impact Index Per Article: 43.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/11/2022] [Indexed: 01/24/2023]
Abstract
Telomeres are specialized nucleoprotein structures at the ends of linear chromosomes that prevent the activation of DNA damage response and repair pathways. Numerous factors localize at telomeres to regulate their length, structure and function, to avert replicative senescence or genome instability and cell death. In humans, Mendelian defects in several of these factors can result in abnormally short or dysfunctional telomeres, causing a group of rare heterogeneous premature-ageing diseases, termed telomeropathies, short-telomere syndromes or telomere biology disorders (TBDs). Here, we review the TBD-causing genes identified so far and describe their main functions associated with telomere biology. We present molecular aspects of TBDs, including genetic anticipation, phenocopy, incomplete penetrance and somatic genetic rescue, which underlie the complexity of these diseases. We also discuss the implications of phenotypic and genetic features of TBDs on fundamental aspects related to human telomere biology, ageing and cancer, as well as on diagnostic, therapeutic and clinical approaches.
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Affiliation(s)
- Patrick Revy
- INSERM UMR 1163, Laboratory of Genome Dynamics in the Immune System, Equipe Labellisée Ligue Nationale contre le Cancer, Paris, France.
- Université Paris Cité, Imagine Institute, Paris, France.
| | - Caroline Kannengiesser
- APHP Service de Génétique, Hôpital Bichat, Paris, France
- Inserm U1152, Université Paris Cité, Paris, France
| | - Alison A Bertuch
- Departments of Paediatrics and Molecular & Human Genetics, Baylor College of Medicine, Houston, TX, USA
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4
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Chu CM, Yu HH, Kao TL, Chen YH, Lu HH, Wu ET, Yang YL, Lin CH, Lin SY, Tsai MJM, Chien YH, Hwu WL, Chen WP, Lee NC, Tseng CK. A missense variant in the nuclear localization signal of DKC1 causes Hoyeraal-Hreidarsson syndrome. NPJ Genom Med 2022; 7:64. [PMID: 36309505 DOI: 10.1038/s41525-022-00335-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Accepted: 10/14/2022] [Indexed: 11/09/2022] Open
Abstract
Hoyeraal-Hreidarsson syndrome (HHS) is the most severe form of dyskeratosis congenita (DC) and is caused by mutations in genes involved in telomere maintenance. Here, we identified male siblings from a family with HHS carrying a hemizygous mutation (c.1345C > G, p.R449G), located in the C-terminal nuclear localization signal (NLS) of the DKC1 gene. These patients exhibit progressive cerebellar hypoplasia, recurrent infections, pancytopenia due to bone marrow failure, and short leukocyte telomere lengths. Single-cell RNA sequencing analysis suggested defects in the NLRP3 inflammasome in monocytes and the activation and maturation of NK cells and B cells. In experiments using induced pluripotent stem cells (iPSCs) from patients, DKC1_R449G iPSCs had short telomere lengths due to reduced levels of human telomerase RNA (hTR) and increased cytosolic proportions of DKC1. Treatment with dihydroquinolizinone RG7834 and 3'deoxyanosine cordycepin rescued telomere length in patient-derived iPSCs. Together, our findings not only provide new insights into immunodeficiency in DC patients but also provide treatment options for telomerase insufficiency disorders.
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Affiliation(s)
- Chia-Mei Chu
- Department of Microbiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Hsin-Hui Yu
- Department of Pediatrics National Taiwan University Children's Hospital Taipei, Taipei, Taiwan
| | - Tsai-Ling Kao
- Department of Microbiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Yi-Hsuan Chen
- Center for Frontier Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Hsuan-Hsuan Lu
- Center for Frontier Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - En-Ting Wu
- Department of Pediatrics National Taiwan University Children's Hospital Taipei, Taipei, Taiwan
| | - Yun-Li Yang
- Department of Pediatrics National Taiwan University Children's Hospital Taipei, Taipei, Taiwan
| | - Chin-Hsien Lin
- Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan
| | - Shin-Yu Lin
- Depatment of Obstetrics and Gynecology, National Taiwan University Hospital, Taipei, Taiwan
| | - Meng-Ju Melody Tsai
- Department of Pediatrics National Taiwan University Children's Hospital Taipei, Taipei, Taiwan
| | - Yin-Hsiu Chien
- Department of Pediatrics National Taiwan University Children's Hospital Taipei, Taipei, Taiwan.,Department of Medical Genetics, National Taiwan University Hospital, Taipei, Taiwan
| | - Wuh-Liang Hwu
- Department of Pediatrics National Taiwan University Children's Hospital Taipei, Taipei, Taiwan.,Department of Medical Genetics, National Taiwan University Hospital, Taipei, Taiwan
| | - Wen-Pin Chen
- Institute of Pharmacology, College of Medicine, National Taiwan University, Taipei City, Taiwan
| | - Ni-Chung Lee
- Department of Pediatrics National Taiwan University Children's Hospital Taipei, Taipei, Taiwan. .,Department of Medical Genetics, National Taiwan University Hospital, Taipei, Taiwan.
| | - Chi-Kang Tseng
- Department of Microbiology, College of Medicine, National Taiwan University, Taipei, Taiwan.
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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] [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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Nagpal N, Tai AK, Nandakumar J, Agarwal S. Domain specific mutations in dyskerin disrupt 3' end processing of scaRNA13. Nucleic Acids Res 2022; 50:9413-9425. [PMID: 36018809 PMCID: PMC9458449 DOI: 10.1093/nar/gkac706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 07/27/2022] [Accepted: 08/10/2022] [Indexed: 12/24/2022] Open
Abstract
Mutations in DKC1 (encoding dyskerin) cause telomere diseases including dyskeratosis congenita (DC) by decreasing steady-state levels of TERC, the non-coding RNA component of telomerase. How DKC1 mutations variably impact numerous other snoRNAs remains unclear, which is a barrier to understanding disease mechanisms in DC beyond impaired telomere maintenance. Here, using DC patient iPSCs, we show that mutations in the dyskerin N-terminal extension domain (NTE) dysregulate scaRNA13. In iPSCs carrying the del37L NTE mutation or engineered to carry NTE mutations via CRISPR/Cas9, but not in those with C-terminal mutations, we found scaRNA13 transcripts with aberrant 3' extensions, as seen when the exoribonuclease PARN is mutated in DC. Biogenesis of scaRNA13 was rescued by repair of the del37L DKC1 mutation by genome-editing, or genetic or pharmacological inactivation of the polymerase PAPD5, which counteracts PARN. Inspection of the human telomerase cryo-EM structure revealed that in addition to mediating intermolecular dyskerin interactions, the NTE interacts with terminal residues of the associated snoRNA, indicating a role for this domain in 3' end definition. Our results provide mechanistic insights into the interplay of dyskerin and the PARN/PAPD5 axis in the biogenesis and accumulation of snoRNAs beyond TERC, broadening our understanding of ncRNA dysregulation in human diseases.
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Affiliation(s)
- Neha Nagpal
- Division of Hematology/Oncology and Stem Cell Program, Boston Children's Hospital; Pediatric Oncology, Dana-Farber Cancer Institute; Harvard Stem Cell Institute; Department of Pediatrics, Harvard Medical School; Manton Center for Orphan Disease Research; Harvard Initiative in RNA Medicine; Boston, MA, USA
| | - Albert K Tai
- Department of Immunology, Tufts University School of Medicine, Boston, MA, USA
- Data Intensive Studies Center, Tufts University, Medford, MA, USA
| | - Jayakrishnan Nandakumar
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Suneet Agarwal
- To whom correspondence should be addressed. Tel: +1 617 919 4610; Fax: +1 617 919 3359;
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7
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Choo S, Lorbeer FK, Regalado SG, Short SB, Wu S, Rieser G, Bertuch AA, Hockemeyer D. Editing TINF2 as a potential therapeutic approach to restore telomere length in dyskeratosis congenita. Blood 2022; 140:608-618. [PMID: 35421215 PMCID: PMC9373014 DOI: 10.1182/blood.2021013750] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Accepted: 03/25/2022] [Indexed: 11/29/2022] Open
Abstract
Mutations in the TINF2 gene, encoding the shelterin protein TIN2, cause telomere shortening and the inherited bone marrow (BM) failure syndrome dyskeratosis congenita (DC). A lack of suitable model systems limits the mechanistic understanding of telomere shortening in the stem cells and thus hinders the development of treatment options for BM failure. Here, we endogenously introduced TIN2-DC mutations in human embryonic stem cells (hESCs) and human hematopoietic stem and progenitor cells (HSPCs) to dissect the disease mechanism and identify a gene-editing strategy that rescued the disease phenotypes. The hESCs with the T284R disease mutation exhibited the short telomere phenotype observed in DC patients. Yet, telomeres in mutant hESCs did not trigger DNA damage responses at telomeres or show exacerbated telomere shortening when differentiated into telomerase-negative cells. Disruption of the mutant TINF2 allele by introducing a frameshift mutation in exon 2 restored telomere length in stem cells and the replicative potential of differentiated cells. Similarly, we introduced TIN2-DC disease variants in human HSPCs to assess the changes in telomere length and proliferative capacity. Lastly, we showed that editing at exon 2 of TINF2 that restored telomere length in hESCs could be generated in TINF2-DC patient HSPCs. Our study demonstrates a simple genetic intervention that rescues the TIN2-DC disease phenotype in stem cells and provides a versatile platform to assess the efficacy of potential therapeutic approaches in vivo.
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Affiliation(s)
- Seunga Choo
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA
| | - Franziska K Lorbeer
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA
| | - Samuel G Regalado
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA
| | - Sarah B Short
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA
| | - Shannon Wu
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA
| | - Gabrielle Rieser
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA
| | - Alison A Bertuch
- Department of Pediatrics, Baylor College of Medicine, Houston, TX
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX
| | - Dirk Hockemeyer
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA
- Chan Zuckerberg Biohub, San Francisco, CA; and
- Innovative Genomics Institute, University of California, Berkeley, Berkeley, CA
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Rubtsova M, Dontsova O. How Structural Features Define Biogenesis and Function of Human Telomerase RNA Primary Transcript. Biomedicines 2022; 10:biomedicines10071650. [PMID: 35884955 PMCID: PMC9313293 DOI: 10.3390/biomedicines10071650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 07/06/2022] [Accepted: 07/06/2022] [Indexed: 11/16/2022] Open
Abstract
Telomerase RNA has been uncovered as a component of the telomerase enzyme, which acts as a reverse transcriptase and maintains the length of telomeres in proliferated eukaryotic cells. Telomerase RNA is considered to have major functions as a template for telomeric repeat synthesis and as a structural scaffold for telomerase. However, investigations of its biogenesis and turnover, as well as structural data, have provided evidence of functions of telomerase RNA that are not associated with telomerase activity. The primary transcript produced from the human telomerase RNA gene encodes for the hTERP protein, which presents regulatory functions related to autophagy, cellular proliferation, and metabolism. This review focuses on the specific features relating to the biogenesis and structure of human telomerase RNA that support the existence of an isoform suitable for functioning as an mRNA. We believe that further investigation into human telomerase RNA biogenesis mechanisms will provide more levels for manipulating cellular homeostasis, survival, and transformation mechanisms, and may contribute to a deeper understanding of the mechanisms of aging.
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Affiliation(s)
- Maria Rubtsova
- Department of Chemistry, A.N. Belozersky Institute of Physico Chemical Biology, Lomonosov Moscow State University, 119991 Moscow, Russia;
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, 117997 Moscow, Russia
- Correspondence:
| | - Olga Dontsova
- Department of Chemistry, A.N. Belozersky Institute of Physico Chemical Biology, Lomonosov Moscow State University, 119991 Moscow, Russia;
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, 117997 Moscow, Russia
- Center of Life Sciences, Skolkovo Institute of Science and Technology, Skolkovo, 121205 Moscow, Russia
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9
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Galati A, Scatolini L, Micheli E, Bavasso F, Cicconi A, Maccallini P, Chen L, Roake CM, Schoeftner S, Artandi SE, Gatti M, Cacchione S, Raffa GD. The S-adenosylmethionine analog sinefungin inhibits the trimethylguanosine synthase TGS1 to promote telomerase activity and telomere lengthening. FEBS Lett 2022; 596:42-52. [PMID: 34817067 DOI: 10.1002/1873-3468.14240] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Revised: 10/16/2021] [Accepted: 11/09/2021] [Indexed: 12/11/2022]
Abstract
Mutations in many genes that control the expression, the function, or the stability of telomerase cause telomere biology disorders (TBDs), such as dyskeratosis congenita, pulmonary fibrosis, and aplastic anemia. Mutations in a subset of the genes associated with TBDs cause reductions of the telomerase RNA moiety hTR, thus limiting telomerase activity. We have recently found that loss of the trimethylguanosine synthase TGS1 increases both hTR abundance and telomerase activity and leads to telomere elongation. Here, we show that treatment with the S-adenosylmethionine analog sinefungin inhibits TGS1 activity, increases the hTR levels, and promotes telomere lengthening in different cell types. Our results hold promise for restoring telomere length in stem and progenitor cells from TBD patients with reduced hTR levels.
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Affiliation(s)
- Alessandra Galati
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Italy
| | - Livia Scatolini
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Italy
| | - Emanuela Micheli
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Italy
| | - Francesca Bavasso
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Italy
| | - Alessandro Cicconi
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Italy
| | - Paolo Maccallini
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Italy
| | - Lu Chen
- Cancer Signaling and Epigenetics Program-Cancer Epigenetics Institute, Fox Chase Cancer Center, Philadelphia, PA, USA
| | - Caitlin M Roake
- Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Stefan Schoeftner
- Dipartimento di Scienze della Vita, Università degli studi di Trieste, Italy
| | - Steven E Artandi
- Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Maurizio Gatti
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Italy
- Istituto di Biologia e Patologia Molecolari del CNR, Roma, Italy
| | - Stefano Cacchione
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Italy
| | - Grazia D Raffa
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Italy
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Garus A, Autexier C. Dyskerin: an essential pseudouridine synthase with multifaceted roles in ribosome biogenesis, splicing, and telomere maintenance. RNA (NEW YORK, N.Y.) 2021; 27:1441-1458. [PMID: 34556550 PMCID: PMC8594475 DOI: 10.1261/rna.078953.121] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Dyskerin and its homologs are ancient and conserved enzymes that catalyze the most common post-transcriptional modification found in cells, pseudouridylation. The resulting pseudouridines provide stability to RNA molecules and regulate ribosome biogenesis and splicing events. Dyskerin does not act independently-it is the core component of a protein heterotetramer, which associates with RNAs that contain the H/ACA motif. The variety of H/ACA RNAs that guide the function of this ribonucleoprotein (RNP) complex highlights the diversity of cellular processes in which dyskerin participates. When associated with small nucleolar (sno) RNAs, it regulates ribosomal (r) RNAs and ribosome biogenesis. By interacting with small Cajal body (sca) RNAs, it targets small nuclear (sn) RNAs to regulate pre-mRNA splicing. As a component of the telomerase holoenzyme, dyskerin binds to the telomerase RNA to modulate telomere maintenance. In a disease context, dyskerin malfunction can result in multiple detrimental phenotypes. Mutations in DKC1, the gene that encodes dyskerin, cause the premature aging syndrome X-linked dyskeratosis congenita (X-DC), a still incurable disorder that typically leads to bone marrow failure. In this review, we present the classical and most recent findings on this essential protein, discussing the evolutionary, structural, and functional aspects of dyskerin and the H/ACA RNP. The latest research underscores the role that dyskerin plays in the regulation of gene expression, translation efficiency, and telomere maintenance, along with the impacts that defective dyskerin has on aging, cell proliferation, haematopoietic potential, and cancer.
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Affiliation(s)
- Alexandre Garus
- Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, H3A 0C7, Canada
- Jewish General Hospital, Lady Davis Institute, Montreal, Quebec, H3T 1E2, Canada
| | - Chantal Autexier
- Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, H3A 0C7, Canada
- Jewish General Hospital, Lady Davis Institute, Montreal, Quebec, H3T 1E2, Canada
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11
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Gain-of-Function Mutations in RPA1 Cause a Syndrome with Short Telomeres and Somatic Genetic Rescue. Blood 2021; 139:1039-1051. [PMID: 34767620 PMCID: PMC8854676 DOI: 10.1182/blood.2021011980] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Accepted: 10/15/2021] [Indexed: 11/20/2022] Open
Abstract
Germline RPA1 gain-of-function missense mutations result in a telomere biology disorder phenotype. Somatic rescue events arise in hematopoiesis secondary to germline RPA1 mutation.
Human telomere biology disorders (TBD)/short telomere syndromes (STS) are heterogeneous disorders caused by inherited loss-of-function mutations in telomere-associated genes. Here, we identify 3 germline heterozygous missense variants in the RPA1 gene in 4 unrelated probands presenting with short telomeres and varying clinical features of TBD/STS, including bone marrow failure, myelodysplastic syndrome, T- and B-cell lymphopenia, pulmonary fibrosis, or skin manifestations. All variants cluster to DNA-binding domain A of RPA1 protein. RPA1 is a single-strand DNA-binding protein required for DNA replication and repair and involved in telomere maintenance. We showed that RPA1E240K and RPA1V227A proteins exhibit increased binding to single-strand and telomeric DNA, implying a gain in DNA-binding function, whereas RPA1T270A has binding properties similar to wild-type protein. To study the mutational effect in a cellular system, CRISPR/Cas9 was used to knock-in the RPA1E240K mutation into healthy inducible pluripotent stem cells. This resulted in severe telomere shortening and impaired hematopoietic differentiation. Furthermore, in patients with RPA1E240K, we discovered somatic genetic rescue in hematopoietic cells due to an acquired truncating cis RPA1 mutation or a uniparental isodisomy 17p with loss of mutant allele, coinciding with stabilized blood counts. Using single-cell sequencing, the 2 somatic genetic rescue events were proven to be independently acquired in hematopoietic stem cells. In summary, we describe the first human disease caused by germline RPA1 variants in individuals with TBD/STS.
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12
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Chemical inhibition of PAPD5/7 rescues telomerase function and hematopoiesis in dyskeratosis congenita. Blood Adv 2021; 4:2717-2722. [PMID: 32559291 DOI: 10.1182/bloodadvances.2020001848] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Accepted: 05/15/2020] [Indexed: 12/24/2022] Open
Abstract
Dyskeratosis congenita (DC) is a pediatric bone marrow failure syndrome caused by germline mutations in telomere biology genes. Mutations in DKC1 (the most commonly mutated gene in DC), the 3' region of TERC, and poly(A)-specific ribonuclease (PARN) cause reduced levels of the telomerase RNA component (TERC) by reducing its stability and accelerating TERC degradation. We have previously shown that depleting wild-type DKC1 levels by RNA interference or expression of the disease-associated A353V mutation in the DKC1 gene leads to decay of TERC, modulated by 3'-end oligoadenylation by noncanonical poly(A) polymerase 5 (PAPD5) followed by 3' to 5' degradation by EXOSC10. Furthermore, the constitutive genetic silencing of PAPD5 is sufficient to rescue TERC levels, restore telomerase function, and elongate telomeres in DKC1_A353V mutant human embryonic stem cells (hESCs). Here, we tested a novel PAPD5/7 inhibitor (RG7834), which was originally discovered in screens against hepatitis B viral loads in hepatic cells. We found that treatment with RG7834 rescues TERC levels, restores correct telomerase localization in DKC1 and PARN-depleted cells, and is sufficient to elongate telomeres in DKC1_A353V hESCs. Finally, treatment with RG7834 significantly improved definitive hematopoietic potential from DKC1_A353V hESCs, indicating that the chemical inhibition of PAPD5 is a potential therapy for patients with DC and reduced TERC levels.
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13
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Chen L, Roake CM, Galati A, Bavasso F, Micheli E, Saggio I, Schoeftner S, Cacchione S, Gatti M, Artandi SE, Raffa GD. Loss of Human TGS1 Hypermethylase Promotes Increased Telomerase RNA and Telomere Elongation. Cell Rep 2021; 30:1358-1372.e5. [PMID: 32023455 PMCID: PMC7156301 DOI: 10.1016/j.celrep.2020.01.004] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 11/09/2019] [Accepted: 12/31/2019] [Indexed: 02/08/2023] Open
Abstract
Biogenesis of the human telomerase RNA (hTR) involves a complex series of posttranscriptional modifications, including hypermethylation of the 5' mono-methylguanosine cap to a tri-methylguanosine cap (TMG). How the TMG cap affects hTR maturation is unknown. Here, we show that depletion of trimethylguanosine synthase 1 (TGS1), the enzyme responsible for cap hypermethylation, increases levels of hTR and telomerase. Diminished trimethylation increases hTR association with the cap-binding complex (CBC) and with Sm chaperone proteins. Loss of TGS1 causes an increase in accumulation of mature hTR in both the nucleus and the cytoplasm compared with controls. In TGS1 mutant cells, increased hTR assembles with telomerase reverse transcriptase (TERT) protein to yield elevated active telomerase complexes and increased telomerase activity, resulting in telomere elongation in cultured human cells. Our results show that TGS1-mediated hypermethylation of the hTR cap inhibits hTR accumulation, restrains levels of assembled telomerase, and limits telomere elongation.
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Affiliation(s)
- Lu Chen
- Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Caitlin M Roake
- Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Alessandra Galati
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Roma, Italy
| | - Francesca Bavasso
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Roma, Italy
| | - Emanuela Micheli
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Roma, Italy
| | - Isabella Saggio
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Roma, Italy
| | - Stefan Schoeftner
- Cancer Epigenetic Group, Laboratorio Nazionale Consorzio Interuniversitario Biotecnologie, Trieste, Italy
| | - Stefano Cacchione
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Roma, Italy
| | - Maurizio Gatti
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Roma, Italy; Istituto di Biologia e Patologia Molecolari (IBPM) del CNR, Roma, Italy
| | - Steven E Artandi
- Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA.
| | - Grazia D Raffa
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Roma, Italy.
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14
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Qin J, Autexier C. Regulation of human telomerase RNA biogenesis and localization. RNA Biol 2021; 18:305-315. [PMID: 32813614 PMCID: PMC7954027 DOI: 10.1080/15476286.2020.1809196] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 08/03/2020] [Accepted: 08/08/2020] [Indexed: 12/16/2022] Open
Abstract
Maintenance of telomeres is essential for genome integrity and replicative capacity in eukaryotic cells. Telomerase, the ribonucleoprotein complex that catalyses telomere synthesis is minimally composed of a reverse transcriptase and an RNA component. The sequence and structural domains of human telomerase RNA (hTR) have been extensively characterized, while the regulation of hTR transcription, maturation, and localization, is not fully understood. Here, we provide an up-to-date review of hTR, with an emphasis on current breakthroughs uncovering the mechanisms of hTR maturation and localization.
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Affiliation(s)
- Jian Qin
- Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada
- Jewish General Hospital, Lady Davis Institute, Montreal, Quebec, Canada
| | - Chantal Autexier
- Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada
- Jewish General Hospital, Lady Davis Institute, Montreal, Quebec, Canada
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15
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Wolska-Kusnierz B, Pastorczak A, Fendler W, Wakulinska A, Dembowska-Baginska B, Heropolitanska-Pliszka E, Piątosa B, Pietrucha B, Kałwak K, Ussowicz M, Pieczonka A, Drabko K, Lejman M, Koltan S, Gozdzik J, Styczynski J, Fedorova A, Miakova N, Deripapa E, Kostyuchenko L, Krenova Z, Hlavackova E, Gennery AR, Sykora KW, Ghosh S, Albert MH, Balashov D, Eapen M, Svec P, Seidel MG, Kilic SS, Tomaszewska A, Wiesik-Szewczyk E, Kreins A, Greil J, Buechner J, Lund B, Gregorek H, Chrzanowska K, Mlynarski W. Hematopoietic Stem Cell Transplantation Positively Affects the Natural History of Cancer in Nijmegen Breakage Syndrome. Clin Cancer Res 2021; 27:575-584. [PMID: 33082212 DOI: 10.1158/1078-0432.ccr-20-2574] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 08/26/2020] [Accepted: 10/16/2020] [Indexed: 11/16/2022]
Abstract
PURPOSE Nijmegen breakage syndrome (NBS) is a DNA repair disorder with a high predisposition to hematologic malignancies. EXPERIMENTAL DESIGN We describe the natural history of NBS, including cancer incidence, risk of death, and the potential effectiveness of hematopoietic stem cell transplantation (HSCT) in preventing both pathologies: malignancy and immunodeficiency. RESULTS Among 241 patients with NBS enrolled in the study from 11 countries, 151 (63.0%) patients were diagnosed with cancer. Incidence rates for primary and secondary cancer, tumor characteristics, and risk factors affecting overall survival (OS) were estimated. The cumulative cancer incidence was 40.21% ± 3.5% and 77.78% ± 3.4% at 10 years and 20 years of follow-up, respectively. Most of the tumors n = 95 (62.9%) were non-Hodgkin lymphomas. Overall, 20 (13.2%) secondary malignancies occurred at a median age of 18 (interquartile range, 13.7-21.5) years. The probability of 20-year overall survival (OS) for the whole cohort was 44.6% ± 4.5%. Patients who developed cancer had a shorter 20-year OS than those without malignancy (29.6% vs. 86.2%; P < 10-5). A total of 49 patients with NBS underwent HSCT, including 14 patients transplanted before malignancy. Patients with NBS with diagnosed cancer who received HSCT had higher 20-year OS than those who did not (42.7% vs. 30.3%; P = 0.038, respectively). In the group of patients who underwent preemptive transplantation, only 1 patient developed cancer, which is 6.7 times lower as compared with nontransplanted patients [incidence rate ratio 0.149 (95% confidence interval, 0.138-0.162); P < 0.0001]. CONCLUSIONS There is a beneficial effect of HSCT on the long-term survival of patients with NBS transplanted in their first complete remission of cancer.
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Affiliation(s)
| | - Agata Pastorczak
- Department Pediatrics, Oncology and Hematology, Medical University of Lodz, Lodz, Poland
| | - Wojciech Fendler
- Department of Biostatistics and Translational Medicine, Medical University of Lodz, Lodz, Poland.,Department of Radiation Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts
| | - Anna Wakulinska
- Department of Oncology, Children's Memorial Health Institute, Warsaw, Poland
| | | | | | - Barbara Piątosa
- Histocompatibility Laboratory, Children's Memorial Health Institute, Warsaw, Poland
| | - Barbara Pietrucha
- Department of Immunology, Children's Memorial Health Institute, Warsaw, Poland
| | - Krzysztof Kałwak
- Department of Pediatric Hematology, Oncology and Bone Marrow Transplantation, Wroclaw Medical University, Wroclaw, Poland
| | - Marek Ussowicz
- Department of Pediatric Hematology, Oncology and Bone Marrow Transplantation, Wroclaw Medical University, Wroclaw, Poland
| | - Anna Pieczonka
- Department of Pediatric Oncology, Poznan University of Medical Sciences, Poznan, Poland
| | - Katarzyna Drabko
- Department of Pediatric Hematology, Oncology and Transplantology, Medical University of Lublin, Poland
| | - Monika Lejman
- Department of Pediatric Hematology, Oncology and Transplantology, Medical University of Lublin, Poland
| | - Sylwia Koltan
- Department of Pediatric Hematology and Oncology, Collegium Medicum, Nicolaus Copernicus University Torun, Bydgoszcz, Poland
| | - Jolanta Gozdzik
- Department of Transplantation, Institute of Pediatrics, Jagiellonian University Medical College, Krakow, Poland
| | - Jan Styczynski
- Department of Pediatric Hematology and Oncology, Collegium Medicum, Nicolaus Copernicus University Torun, Bydgoszcz, Poland
| | - Alina Fedorova
- Belarusian Research Center for Pediatric Oncology and Hematology, Minsk, Belarus
| | - Natalia Miakova
- Department of Pediatric Oncology and Hematology, Federal Research Center for Pediatric Hematology, Oncology and Immunology, Moscow, Russia
| | - Elena Deripapa
- Department of Immunology and Hematopoietic Stem Cell Transplantation, Federal Research Center for Pediatric Hematology, Oncology and Immunology, Moscow, Russia
| | - Larysa Kostyuchenko
- Department of Pediatric Immunology, Western Ukrainian Specialized Children's Medical Centre, Lviv, Ukraine
| | - Zdenka Krenova
- Department of Pediatric Oncology, University Hospital and Faculty of Medicine, Masaryk University, Brno, Czech Republic
| | - Eva Hlavackova
- Department of Pediatric Oncology, University Hospital and Faculty of Medicine, Masaryk University, Brno, Czech Republic.,Department of Clinical Immunology and Allergology, St. Anne's University Hospital in Brno and Faculty of Medicine, Masaryk University, Brno, Czech Republic
| | - Andrew R Gennery
- Translational and Clinical Research Institute, Newcastle University and Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle, United Kingdom
| | - Karl-Walter Sykora
- Department of Pediatrics, Hannover Medical School (MHH), Hannover, Germany
| | - Sujal Ghosh
- Department of Pediatric Oncology, Hematology and Clinical Immunology, Medical Faculty, Center of Child and Adolescent Health, Heinrich-Heine-University, Düsseldorf, Germany
| | - Michael H Albert
- Dr. von Hauner University Children's Hospital, Ludwig-Maximilians-University, Munich, Germany
| | - Dmitry Balashov
- Department of Hematopoietic Stem Cell Transplantation, Dmitriy Rogachev National Center for Pediatric Hematology, Oncology, and Immunology, Moscow, Russia
| | - Mary Eapen
- Center for International Blood and Marrow Transplant, Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Peter Svec
- Department of Pediatric Hematology and Oncology, Comenius University and National Institute of Children's Diseases, Bratislava, Slovakia
| | - Markus G Seidel
- Research Unit Pediatric Hematology and Immunology, Division of Pediatric Hematology-Oncology, Department of Pediatrics and Adolescent Medicine, Medical University Graz, Graz, Austria
| | - Sara S Kilic
- Pediatric Immunology Division, Department of Pediatrics, Uludag University Medical Faculty, Bursa, Turkey
| | - Agnieszka Tomaszewska
- Department of Hematology, Oncology and Internal Medicine, Medical University of Warsaw, Warsaw, Poland
| | - Ewa Wiesik-Szewczyk
- Department of Internal Medicine, Pneumonology, Allergology and Clinical Immunology, Central Clinical Hospital of the Ministry of National Defense, Military Institute of Medicine, Warsaw, Poland
| | - Alexandra Kreins
- Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
| | - Johann Greil
- Department of Pediatric Hematology and Oncology, University Hospital, Heidelberg, Germany
| | - Jochen Buechner
- Department of Pediatric Hematology and Oncology, Oslo University Hospital, Oslo, Norway
| | - Bendik Lund
- Pediatric Department, St Olav University Hospital, Trondheim, Norway
| | - Hanna Gregorek
- Department of Microbiology and Clinical Immunology, The Children's Memorial Health Institute, Warsaw, Poland
| | - Krystyna Chrzanowska
- Department of Medical Genetics, The Children's Memorial Health Institute, Warsaw, Poland
| | - Wojciech Mlynarski
- Department Pediatrics, Oncology and Hematology, Medical University of Lodz, Lodz, Poland.
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16
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Grill S, Nandakumar J. Molecular mechanisms of telomere biology disorders. J Biol Chem 2021; 296:100064. [PMID: 33482595 PMCID: PMC7948428 DOI: 10.1074/jbc.rev120.014017] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2020] [Revised: 11/11/2020] [Accepted: 11/12/2020] [Indexed: 12/20/2022] Open
Abstract
Genetic mutations that affect telomerase function or telomere maintenance result in a variety of diseases collectively called telomeropathies. This wide spectrum of disorders, which include dyskeratosis congenita, pulmonary fibrosis, and aplastic anemia, is characterized by severely short telomeres, often resulting in hematopoietic stem cell failure in the most severe cases. Recent work has focused on understanding the molecular basis of these diseases. Mutations in the catalytic TERT and TR subunits of telomerase compromise activity, while others, such as those found in the telomeric protein TPP1, reduce the recruitment of telomerase to the telomere. Mutant telomerase-associated proteins TCAB1 and dyskerin and the telomerase RNA maturation component poly(A)-specific ribonuclease affect the maturation and stability of telomerase. In contrast, disease-associated mutations in either CTC1 or RTEL1 are more broadly associated with telomere replication defects. Yet even with the recent surge in studies decoding the mechanisms underlying these diseases, a significant proportion of dyskeratosis congenita mutations remain uncharacterized or poorly understood. Here we review the current understanding of the molecular basis of telomeropathies and highlight experimental data that illustrate how genetic mutations drive telomere shortening and dysfunction in these patients. This review connects insights from both clinical and molecular studies to create a comprehensive view of the underlying mechanisms that drive these diseases. Through this, we emphasize recent advances in therapeutics and pinpoint disease-associated variants that remain poorly defined in their mechanism of action. Finally, we suggest future avenues of research that will deepen our understanding of telomere biology and telomere-related disease.
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Affiliation(s)
- Sherilyn Grill
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, USA
| | - Jayakrishnan Nandakumar
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, USA.
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17
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Fraga de Andrade I, Mehta C, Bresnick EH. Post-transcriptional control of cellular differentiation by the RNA exosome complex. Nucleic Acids Res 2020; 48:11913-11928. [PMID: 33119769 PMCID: PMC7708067 DOI: 10.1093/nar/gkaa883] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 09/21/2020] [Accepted: 09/30/2020] [Indexed: 12/12/2022] Open
Abstract
Given the complexity of intracellular RNA ensembles and vast phenotypic remodeling intrinsic to cellular differentiation, it is instructive to consider the role of RNA regulatory machinery in controlling differentiation. Dynamic post-transcriptional regulation of protein-coding and non-coding transcripts is vital for establishing and maintaining proteomes that enable or oppose differentiation. By contrast to extensively studied transcriptional mechanisms governing differentiation, many questions remain unanswered regarding the involvement of post-transcriptional mechanisms. Through its catalytic activity to selectively process or degrade RNAs, the RNA exosome complex dictates the levels of RNAs comprising multiple RNA classes, thereby regulating chromatin structure, gene expression and differentiation. Although the RNA exosome would be expected to control diverse biological processes, studies to elucidate its biological functions and how it integrates into, or functions in parallel with, cell type-specific transcriptional mechanisms are in their infancy. Mechanistic analyses have demonstrated that the RNA exosome confers expression of a differentiation regulatory receptor tyrosine kinase, downregulates the telomerase RNA component TERC, confers genomic stability and promotes DNA repair, which have considerable physiological and pathological implications. In this review, we address how a broadly operational RNA regulatory complex interfaces with cell type-specific machinery to control cellular differentiation.
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Affiliation(s)
- Isabela Fraga de Andrade
- Wisconsin Blood Cancer Research Institute, Department of Cell and Regenerative Biology, Carbone Cancer Center, University of Wisconsin School of Medicine and Public Health, 1111 Highland Avenue, 4009 WIMR, Madison, WI 53705, USA
| | - Charu Mehta
- Wisconsin Blood Cancer Research Institute, Department of Cell and Regenerative Biology, Carbone Cancer Center, University of Wisconsin School of Medicine and Public Health, 1111 Highland Avenue, 4009 WIMR, Madison, WI 53705, USA
| | - Emery H Bresnick
- Wisconsin Blood Cancer Research Institute, Department of Cell and Regenerative Biology, Carbone Cancer Center, University of Wisconsin School of Medicine and Public Health, 1111 Highland Avenue, 4009 WIMR, Madison, WI 53705, USA
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18
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Block TM, Young JAT, Javanbakht H, Sofia MJ, Zhou T. Host RNA quality control as a hepatitis B antiviral target. Antiviral Res 2020; 186:104972. [PMID: 33242518 DOI: 10.1016/j.antiviral.2020.104972] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 10/30/2020] [Accepted: 11/03/2020] [Indexed: 12/12/2022]
Abstract
Inhibition of the host RNA polyadenylating polymerases, PAPD5 and PAPD7 (PAPD5/7), with dihydroquinolizinone, a small orally available, molecule, results in a rapid and selective degradation of hepatitis B virus (HBV) RNA, and hence reduction in the amounts of viral gene products. DHQ, is a first in class investigational agent and could represent an entirely new category of HBV antivirals. PAPD5 and PAPD7 are non-canonical, cell specified, polyadenylating polymerases, also called terminal nucleotidyl transferases 4B and 4A (TENT4B/A), respectively. They are involved in the degradation of poor-quality cell transcripts, mostly non-coding RNAs and in the maturation of a sub-set of transcripts. They also appear to play a role in shielding some mRNA from degradation. The results of studies with DHQ, along with other recent findings, provide evidence that repression of the PAPD5/7 arm of the cell "RNA quality control" pathway, causes a profound (multi-fold) reduction rather than increase, in the amount of HBV pre-genomic, pre-core and HBsAg mRNA levels in tissue culture and animal models, as well. In this review we will briefly discuss the need for new HBV therapeutics and provide background about HBV transcription. We also discuss cellular degradation of host transcripts, as it relates to a new family of anti-HBV drugs that interfere with these processes. Finally, since HBV mRNA maturation appears to be selectively sensitive to PAPD5/7 inhibition in hepatocytes, we discuss the possibility of targeting host RNA "quality control" as an antiviral strategy.
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Affiliation(s)
| | - John A T Young
- Roche Pharma Research & Early Development, Roche Innovation Center Basel, F.Hoffmann-La Roche Ltd, Basel, Switzerland.
| | - Hassan Javanbakht
- SQZ Biotechnologies, 200 Arsenal Yards Blvd, Suite 210, Watertown, MA, 02472, USA.
| | - Michael J Sofia
- Arbutus Biopharma, Inc, 701 Veterans Circle, Warminster, PA, 18974, USA.
| | - Tianlun Zhou
- Baruch S. Blumberg Institute, Doylestown, PA, 18902, USA.
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19
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Munroe M, Niero EL, Fok WC, Vessoni AT, Jeong H, Brenner KA, Batista LFZ. Telomere Dysfunction Activates p53 and Represses HNF4α Expression Leading to Impaired Human Hepatocyte Development and Function. Hepatology 2020; 72:1412-1429. [PMID: 32516515 PMCID: PMC7693115 DOI: 10.1002/hep.31414] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 05/04/2020] [Accepted: 05/19/2020] [Indexed: 12/18/2022]
Abstract
BACKGROUND AND AIMS Telomere attrition is a major risk factor for end-stage liver disease. Due to a lack of adequate models and intrinsic difficulties in studying telomerase in physiologically relevant cells, the molecular mechanisms responsible for liver disease in patients with telomere syndromes remain elusive. To circumvent that, we used genome editing to generate isogenic human embryonic stem cells (hESCs) harboring clinically relevant mutations in telomerase and subjected them to an in vitro, stage-specific hepatocyte differentiation protocol that resembles hepatocyte development in vivo. APPROACH AND RESULTS Using this platform, we observed that while telomerase is highly expressed in hESCs, it is quickly silenced, specifically due to telomerase reverse transcriptase component (TERT) down-regulation, immediately after endoderm differentiation and completely absent in in vitro-derived hepatocytes, similar to what is observed in human primary hepatocytes. While endoderm derivation is not impacted by telomere shortening, progressive telomere dysfunction impaired hepatic endoderm formation. Consequently, hepatocyte derivation, as measured by expression of specific hepatic markers as well by albumin expression and secretion, is severely compromised in telomerase mutant cells with short telomeres. Interestingly, this phenotype was not caused by cell death induction or senescence. Rather, telomere shortening prevents the up-regulation and activation of human hepatocyte nuclear factor 4 alpha (HNF4α) in a p53-dependent manner. Both reactivation of telomerase and silencing of p53 rescued hepatocyte formation in telomerase mutants. Likewise, the conditional expression (doxycycline-controlled) of HNF4α, even in cells that retained short telomeres, accrued DNA damage, and exhibited p53 stabilization, successfully restored hepatocyte formation from hESCS. CONCLUSIONS Our data show that telomere dysfunction acts as a major regulator of HNF4α during hepatocyte development, pointing to a target in the treatment of liver disease in telomere-syndrome patients.
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Affiliation(s)
- Michael Munroe
- Department of MedicineWashington University in St. LouisSt. LouisMO
| | | | - Wilson Chun Fok
- Department of MedicineWashington University in St. LouisSt. LouisMO
| | | | - Ho‐Chang Jeong
- Department of MedicineWashington University in St. LouisSt. LouisMO
| | - Kirsten Ann Brenner
- Department of MedicineWashington University in St. LouisSt. LouisMO
- Present address:
Department of Molecular, Cellular, and Developmental BiologyUniversity of MichiganAnn ArborMI
| | - Luis Francisco Zirnberger Batista
- Department of MedicineWashington University in St. LouisSt. LouisMO
- Department of Developmental BiologyWashington University in St. LouisSt. LouisMO
- Center of Regenerative MedicineWashington University in St. LouisSt. LouisMO
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20
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Nagpal N, Agarwal S. Telomerase RNA processing: Implications for human health and disease. Stem Cells 2020; 38:10.1002/stem.3270. [PMID: 32875693 PMCID: PMC7917152 DOI: 10.1002/stem.3270] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 08/11/2020] [Indexed: 11/11/2022]
Abstract
Telomeres are composed of repetitive DNA sequences that are replenished by the enzyme telomerase to maintain the self-renewal capacity of stem cells. The RNA component of human telomerase (TERC) is the essential template for repeat addition by the telomerase reverse transcriptase (TERT), and also serves as a scaffold for several factors comprising the telomerase ribonucleoprotein (RNP). Unique features of TERC regulation and function have been informed not only through biochemical studies but also through human genetics. Disease-causing mutations impact TERC biogenesis at several levels including RNA transcription, post-transcriptional processing, folding, RNP assembly, and trafficking. Defects in TERC reduce telomerase activity and impair telomere maintenance, thereby causing a spectrum of degenerative diseases called telomere biology disorders (TBDs). Deciphering mechanisms of TERC dysregulation have led to a broader understanding of noncoding RNA biology, and more recently points to new therapeutic strategies for TBDs. In this review, we summarize over two decades of work revealing mechanisms of human telomerase RNA biogenesis, and how its disruption causes human diseases.
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Affiliation(s)
- Neha Nagpal
- Division of Hematology/Oncology and Stem Cell Program, Boston Children’s Hospital, Boston, Massachusetts
- Pediatric Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts
- Harvard Initiative for RNA Medicine and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts
- Harvard Stem Cell Institute, Boston, Massachusetts
| | - Suneet Agarwal
- Division of Hematology/Oncology and Stem Cell Program, Boston Children’s Hospital, Boston, Massachusetts
- Pediatric Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts
- Harvard Initiative for RNA Medicine and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts
- Harvard Stem Cell Institute, Boston, Massachusetts
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21
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Abstract
A snapshot of noteworthy recent developments in the patent literature of relevance to pharmaceutical and medical research and development.
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22
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Mangaonkar AA, Patnaik MM. Hereditary Predisposition to Hematopoietic Neoplasms: When Bloodline Matters for Blood Cancers. Mayo Clin Proc 2020; 95:1482-1498. [PMID: 32571604 DOI: 10.1016/j.mayocp.2019.12.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 11/23/2019] [Accepted: 12/11/2019] [Indexed: 02/07/2023]
Abstract
With the advent of precision genomics, hereditary predisposition to hematopoietic neoplasms- collectively known as hereditary predisposition syndromes (HPS)-are being increasingly recognized in clinical practice. Familial clustering was first observed in patients with leukemia, which led to the identification of several germline variants, such as RUNX1, CEBPA, GATA2, ANKRD26, DDX41, and ETV6, among others, now established as HPS, with tendency to develop myeloid neoplasms. However, evidence for hereditary predisposition is also apparent in lymphoid and plasma--cell neoplasms, with recent discoveries of germline variants in genes such as IKZF1, SH2B3, PAX5 (familial acute lymphoblastic leukemia), and KDM1A/LSD1 (familial multiple myeloma). Specific inherited bone marrow failure syndromes-such as GATA2 haploinsufficiency syndromes, short telomere syndromes, Shwachman-Diamond syndrome, Diamond-Blackfan anemia, severe congenital neutropenia, and familial thrombocytopenias-also have an increased predisposition to develop myeloid neoplasms, whereas inherited immune deficiency syndromes, such as ataxia-telangiectasia, Bloom syndrome, Wiskott Aldrich syndrome, and Bruton agammaglobulinemia, are associated with an increased risk for lymphoid neoplasms. Timely recognition of HPS is critical to ensure safe choice of donors and/or conditioning-regimen intensity for allogeneic hematopoietic stem-cell transplantation and to enable direction of appropriate genomics-driven personalized therapies. The purpose of this review is to provide a comprehensive overview of HPS and serve as a useful reference for clinicians to recognize relevant signs and symptoms among patients to enable timely screening and referrals to pursue germline assessment. In addition, we also discuss our institutional approach toward identification of HPS and offer a stepwise diagnostic and management algorithm.
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Affiliation(s)
| | - Mrinal M Patnaik
- Division of Hematology, Department of Medicine, Mayo Clinic, Rochester, MN.
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23
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Brenner KA, Nandakumar J. Small Molecules Restore Telomeres in Patient Stem Cells. Trends Pharmacol Sci 2020; 41:506-508. [PMID: 32482456 DOI: 10.1016/j.tips.2020.05.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 05/18/2020] [Indexed: 11/30/2022]
Abstract
Genetic defects in telomere maintenance result in stem cell exhaustion and a spectrum of telomere biology diseases. Systemic treatments beyond organ transplantation are lacking for these diseases. Nagpal and colleagues identified small molecules that restore telomere maintenance in patient-derived stem cells, offering a promising therapy for telomere biology diseases.
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Affiliation(s)
- Kirsten Ann Brenner
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Jayakrishnan Nandakumar
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA.
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24
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Small-Molecule PAPD5 Inhibitors Restore Telomerase Activity in Patient Stem Cells. Cell Stem Cell 2020; 26:896-909.e8. [PMID: 32320679 DOI: 10.1016/j.stem.2020.03.016] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 01/21/2020] [Accepted: 03/27/2020] [Indexed: 12/12/2022]
Abstract
Genetic lesions that reduce telomerase activity inhibit stem cell replication and cause a range of incurable diseases, including dyskeratosis congenita (DC) and pulmonary fibrosis (PF). Modalities to restore telomerase in stem cells throughout the body remain unclear. Here, we describe small-molecule PAPD5 inhibitors that demonstrate telomere restoration in vitro, in stem cell models, and in vivo. PAPD5 is a non-canonical polymerase that oligoadenylates and destabilizes telomerase RNA component (TERC). We identified BCH001, a specific PAPD5 inhibitor that restored telomerase activity and telomere length in DC patient induced pluripotent stem cells. When human blood stem cells engineered to carry DC-causing PARN mutations were xenotransplanted into immunodeficient mice, oral treatment with a repurposed PAPD5 inhibitor, the dihydroquinolizinone RG7834, rescued TERC 3' end maturation and telomere length. These findings pave the way for developing systemic telomere therapeutics to counteract stem cell exhaustion in DC, PF, and possibly other aging-related diseases.
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25
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Roake CM, Artandi SE. Regulation of human telomerase in homeostasis and disease. Nat Rev Mol Cell Biol 2020; 21:384-397. [PMID: 32242127 DOI: 10.1038/s41580-020-0234-z] [Citation(s) in RCA: 163] [Impact Index Per Article: 40.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/05/2020] [Indexed: 12/14/2022]
Abstract
Telomerase is a ribonucleoprotein complex, the catalytic core of which includes the telomerase reverse transcriptase (TERT) and the non-coding human telomerase RNA (hTR), which serves as a template for the addition of telomeric repeats to chromosome ends. Telomerase expression is restricted in humans to certain cell types, and telomerase levels are tightly controlled in normal conditions. Increased levels of telomerase are found in the vast majority of human cancers, and we have recently begun to understand the mechanisms by which cancer cells increase telomerase activity. Conversely, germline mutations in telomerase-relevant genes that decrease telomerase function cause a range of genetic disorders, including dyskeratosis congenita, idiopathic pulmonary fibrosis and bone marrow failure. In this Review, we discuss the transcriptional regulation of human TERT, hTR processing, assembly of the telomerase complex, the cellular localization of telomerase and its recruitment to telomeres, and the regulation of telomerase activity. We also discuss the disease relevance of each of these steps of telomerase biogenesis.
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Affiliation(s)
- Caitlin M Roake
- Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA, USA.,Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA.,Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, USA
| | - Steven E Artandi
- Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA, USA. .,Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA. .,Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, USA.
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26
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MacNeil DE, Lambert-Lanteigne P, Autexier C. N-terminal residues of human dyskerin are required for interactions with telomerase RNA that prevent RNA degradation. Nucleic Acids Res 2019; 47:5368-5380. [PMID: 30931479 PMCID: PMC6547437 DOI: 10.1093/nar/gkz233] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 03/19/2019] [Accepted: 03/25/2019] [Indexed: 12/16/2022] Open
Abstract
The telomerase holoenzyme responsible for maintaining telomeres in vertebrates requires many components in vivo, including dyskerin. Dyskerin binds and regulates the accumulation of the human telomerase RNA, hTR, as well as other non-coding RNAs that share the conserved H/ACA box motif. The precise mechanism by which dyskerin controls hTR levels is unknown, but is evidenced by defective hTR accumulation caused by substitutions in dyskerin, that are observed in the X-linked telomere biology disorder dyskeratosis congenita (X-DC). To understand the role of dyskerin in hTR accumulation, we analyzed X-DC substitutions K39E and K43E in the poorly characterized dyskerin N-terminus, and A353V within the canonical RNA binding domain (the PUA). These variants exhibited impaired binding to hTR and polyadenylated hTR species, while interactions with other H/ACA RNAs appear largely unperturbed by the N-terminal substitutions. hTR accumulation and telomerase activity defects of dyskerin-deficient cells were rescued by wildtype dyskerin but not the variants. hTR 3′ extended or polyadenylated species did not accumulate, suggesting hTR precursor degradation occurs upstream of mature complex assembly in the absence of dyskerin binding. Our findings demonstrate that the dyskerin-hTR interaction mediated by PUA and N-terminal residues of dyskerin is crucial to prevent unchecked hTR degradation.
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Affiliation(s)
- Deanna E MacNeil
- Jewish General Hospital of McGill University, Lady Davis Institute, Montreal, Quebec H3T 1E2, Canada.,Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec H3A 0C7, Canada
| | - Patrick Lambert-Lanteigne
- Jewish General Hospital of McGill University, Lady Davis Institute, Montreal, Quebec H3T 1E2, Canada
| | - Chantal Autexier
- Jewish General Hospital of McGill University, Lady Davis Institute, Montreal, Quebec H3T 1E2, Canada.,Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec H3A 0C7, Canada
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27
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Laudadio I, Carissimi C, Fulci V. How RNAi machinery enters the world of telomerase. Cell Cycle 2019; 18:1056-1067. [PMID: 31014212 PMCID: PMC6592256 DOI: 10.1080/15384101.2019.1609834] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 04/01/2019] [Accepted: 04/14/2019] [Indexed: 12/27/2022] Open
Abstract
Human telomerase holoenzyme consists of the catalytic component TERT and the template RNA TERC. However, a network of accessory proteins plays key roles in its assembly, localization and stability. Defects in genes involved in telomerase biology affect the renewal of critical stem cell populations and cause disorders such as telomeropathies. Moreover, activation of telomerase in somatic cells allows neoplastic cells to proliferate indefinitely, thus contributing to tumorigenesis. For these reasons, identification of new players involved in telomerase regulation is crucial for the determination of novel therapeutic targets and biomarkers. In the very last years, increasing evidence describes components of the RNAi machinery as a new layer of complexity in human telomerase activity. In this review, we will discuss how AGO2 and other proteins which collaborate with AGO2 in RNAi pathway play a pivotal role in TERC stability and function.
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Affiliation(s)
- Ilaria Laudadio
- Department of Molecular Medicine, “Sapienza” University of Rome, Rome, Italy
| | - Claudia Carissimi
- Department of Molecular Medicine, “Sapienza” University of Rome, Rome, Italy
| | - Valerio Fulci
- Department of Molecular Medicine, “Sapienza” University of Rome, Rome, Italy
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