DOCSLIB.ORG

Telomeric Transcripts Stimulate Telomere Recombination to Suppress Senescence in Cells Lacking Telomerase

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Telomeric Transcripts Stimulate Telomere Recombination to Suppress Senescence in Cells Lacking Telomerase Telomeric transcripts stimulate telomere recombination to suppress senescence in cells lacking telomerase Tai-Yuan Yua, Yu-wen Kaob, and Jing-Jer Lina,b,1 aInstitute of Biopharmaceutical Sciences, National Yang-Ming University, Taipei 112, Taiwan; and bInstitute of Biochemistry and Molecular Biology, National Taiwan University College of Medicine, Taipei 10051, Taiwan Edited by Philip C. Hanawalt, Stanford University, Stanford, CA, and approved January 21, 2014 (received for review April 19, 2013) In human somatic cells or yeast cells lacking telomerase, telomeres Telomeres are transcribed from subtelomeric regions into are shortened upon each cell division. This gradual shortening of large noncoding telomeric repeat-containing RNA (TERRA) by telomeres eventually leads to senescence. However, a small RNA polymerase II. TERRA has been implicated in several population of telomerase-deficient cells can survive by bypassing telomere-related and non-telomere-related functions (11–15). senescence through the activation of alternative recombination For example, TERRA binds to telomeres and participates in pathways to maintain their telomeres. Although genes involved in regulating telomerase and the organization and maintenance of telomere recombination have been identified, mechanisms that telomeric chromatin throughout development and cellular dif- trigger telomere recombination are less known. The THO (sup- ferentiation (11–13, 16). A study using an inducible telomere pressor of the transcriptional defects of Hpr1 mutants by over- transcription system to investigate the effect of TERRA expression) complex is involved in transcription elongation and expression on telomere function (17) showed that telomeric mRNA export. Here we demonstrate that mutations in THO complex transcription causes telomere shortening in a DNA replication- components can stimulate early senescence and type II telo- dependent manner; moreover, in the absence of both telomerase mere recombination in cells lacking telomerase. The accumula- and telomere recombination, overexpression of TERRA at tion of telomere-associated noncoding telomere repeat-containing a single telomere is sufficient to induce early-onset senescence. RNA (TERRA) is required for the observed telomere effects in THO Although the cellular localization of TERRA has not been dem- complex mutants; reduced transcriptional efficiency, or overex- onstrated in yeast, RNA fluorescence in situ hybridization studies have showed that at least a fraction of TERRA molecules in pression of RNase H or C – A RNA can severely impair the type II 1 3 human and mouse cells are stably associated with telomeric telomere recombination. The results highlight a unique function for heterochromatin (11, 13). This telomeric association of TERRA telomere-associated TERRA, in the formation of type II survivors. More- may be achieved through interacting with telomeric proteins or, over, because TERRA is a long noncoding RNA, these results reveal alternatively, through the direct formation of telomeric DNA– a function for long noncoding RNA in regulating recombination. RNA hybrids. THO (a suppressor of the transcriptional defects of Hpr1 n Saccharomyces cerevisiae, the telomere length is typically mutants by overexpression) is a conserved eukaryotic complex Imaintained by the constitutive expression of telomerase. How- involved in transcription elongation and mRNA export (18, 19). ever, in cells lacking telomerase, a gradual loss of telomere In S. cerevisiae, the THO complex comprises four proteins: Hpr1, length during rounds of cell division eventually leads to the Tho2, Mft1, and Thp2 (18). In mutants with a defective THO uncapping of telomeres and induces a checkpoint-mediated cell- complex, stalled transcription and transcriptional DNA–RNA cycle arrest termed senescence (1, 2). Although most cells die in hybrids stimulate transcription-associated recombination, caus- – the absence of telomerase, rare survivors do escape senescence ing genome instability and chromosome fragility (20 23). Here, by maintaining their telomeres through a radiation sensitive 52 (RAD52)-dependent recombination mechanism (3–5). At least Significance two different types of telomeric recombination events contribute to telomere elongation in the absence of telomerase, generating Telomerase expression is essential for the long-term pro- two types of survivor cells that can be distinguished by different liferation of most cancer cells. In cancer cells lacking telomer- growth rates and distinct telomere patterns on Southern blots (3, ase, an alternative lengthening of telomeres (ALT) pathway is 6–8). Type I survivors arise through gene-conversion events that activated to maintain telomere length through telomere re- occur in the Y′ sequence elements present in the subtelomeric combination. Using yeast as a model system, we found that the BIOCHEMISTRY region of most chromosomes; these cells have short terminal noncoding telomeric repeat-containing RNA (TERRA) plays a ma- telomere repeats and grow slowly. In contrast, type II survivors jor role in recombination-mediated maintenance of telomere in have long, heterogeneous tracts of telomeric repeats, similar to telomerase-deficient cells. Increased levels of telomere-associated – the survivors identified in telomerase-deficient Kluyveromyces TERRA result in the accumulation of telomeric DNA RNA hybrids lactis and mammalian alternative lengthening of telomeres and induce telomere recombination. Because the structure and (ALT) cells (5, 9). The generation of both types of survivors and function of TERRA are conserved among eukaryotes, our find- ings suggest that the accumulation of telomere-associated the stability of their telomeres depend on the function of RAD52 TERRA might also have a role in modulating the occurrence of (3–5). However, two genetically distinct recombination pathways, ALT in cancer cells. defined by RAD50 and RAD51, govern the RAD52-dependent generation of specific types of survivors (6, 10). The type I sur- Author contributions: T.-Y.Y. and J.-J.L. designed research; T.-Y.Y. and Y.-w.K. performed vivors are absent in the rad51Δ strain, whereas type II survivors research; T.-Y.Y., Y.-w.K., and J.-J.L. analyzed data; and T.-Y.Y. and J.-J.L. wrote the paper. cannot arise in the rad50Δ strain (10). Neither type of survivor The authors declare no conflict of interest. can be found in the rad51Δ rad50Δ double mutant (6). Despite This article is a PNAS Direct Submission. the identification of these important genes that are involved in 1To whom correspondence should be addressed. E-mail: [email protected]. telomere recombination, mechanisms triggering telomere re- This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10. combination have not been fully elucidated. 1073/pnas.1307415111/-/DCSupplemental. www.pnas.org/cgi/doi/10.1073/pnas.1307415111 PNAS | March 4, 2014 | vol. 111 | no. 9 | 3377–3382 Downloaded by guest on September 26, 2021 we used mutants of THO complex components to test the role of A C 10 TERRA in telomere recombination. We found that premature senescence 8 tlc1 hpr1 wt senescence and formation of RAD50-dependent type II survivors tlc1 hpr1 6 were induced in THO mutants that were also lacking functional 0 1 0 1 0 1 0 1 streaks 600 (kbp) OD 4 tlc1 telomerase. The observed premature senescence and telomere 8.0 2 tlc1 tho2 tlc1 mft1 recombination was transcription-dependent and required the 5.0 tlc1 hpr1 tlc1 thp2 accumulation of TERRA in telomeric DNA–RNA hybrids. Our 4.0 0 results have revealed a mechanism in which the accumulation 3.0 30 40 50 60 70 80 90 100 110 120 Generations of telomere-associated TERRA in THO mutants induces re- 2.0 1.5 Y’-tel tlc1 tlc1 tho2 tlc1 hpr1 combination in the absence of telomerase. More significantly, 1.0 D (kbp) we found that telomere-associated TERRA plays a role in type II 8.0 6.0 telomere recombination to facilitate the bypass of senescence in B 4.0 cells lacking telomerase. 2.0 1 1.5 2 4 1.0 Results tlc1 0.5 3 0.25 Mutations in the THO Complex Components Induce Early Senescence Restreaks Dilutions12 3 4 5 6 7 1234567 1234567 and Type II Survivor Formation in the Absence of Telomerase. Our tlc1 mft1 tlc1 thp2 previous work demonstrated that telomeres are lengthened by (kbp) tlc1 hpr1 ∼ – tho2Δ hpr1Δ tlc1 tho2 8.0 50 100 bp in or strains but remain unaffected in 6.0 mft1Δ or thp2Δ cells; moreover, mutations in these THO com- 4.0 plex components affect telomere length by reducing the expres- 2.0 1.5 sion of a telomere-associated protein, Rif1 (24). To determine 1.0 tlc1 mft1 hpr1 tho2 tlc1 thp2 0.5 whether telomere lengthening in and cells requires 0.25 telomerase activity, the telomerase RNA component-encoding Dilutions 1234567 1234567 gene TLC1 was deleted in hpr1 and tho2 cells. Lacking functional E pRS42- pRS426 RIF1 tlc1 tlc1 tho2 tlc1 hpr1 telomerase, tlc1 cells exhibited progressive shortening of telo- F (kbp) meres (Fig. 1A), whereas the lengths of Y′-bearing telomeres in 8.0 tlc1 6.0 hpr1 cells appeared ∼75 bp longer than those in wild-type cells, 4.0 as reported (24). The telomere lengths in tlc1 hpr1 cells were 2.0 1.5 similar to those in tlc1 cells, indicating that the increase of 1.0 pRS426 telomere lengths observed in hpr1 and tho2 cells required func- 0.5 0.25 tional telomerase. Interestingly, the type II survivor pattern was tlc1 tho2 frequently observed in tlc1 hpr1 and tlc1 tho2 double-mutant cells 8.0 after restreaking, but not in wild-type or single-mutant cells (Fig. 6.0 RIF1 1A and Fig. S1). The results suggest that the THO complex might 4.0 - tlc1 hpr1 2.0 somehow affect telomere recombination. 1.5 1.0 1 pRS426 To determine the role of the THO complex in senescence and 0.5 cell survival in the absence of telomerase, we examined the 2 4 0.25 growth of tlc1 cells with THO mutations. Cells were harvested 3 Restreaks Dilutions 12345678 12345678 12345678 directly from freshly dissected tlc1 spores and assayed by suc- HPR1 THO2 cessive restreaking of grown colonies onto fresh plates four Fig.
Load more

Recommended publications
  • Telomeres.Pdf
    Telomeres Secondary article Elizabeth H Blackburn, University of California, San Francisco, California, USA Article Contents . Introduction Telomeres are specialized DNA–protein structures that occur at the ends of eukaryotic . The Replication Paradox chromosomes. A special ribonucleoprotein enzyme called telomerase is required for the . Structure of Telomeres synthesis and maintenance of telomeric DNA. Synthesis of Telomeric DNA by Telomerase . Functions of Telomeres Introduction . Telomere Homeostasis . Alternatives to Telomerase-generated Telomeric DNA Telomeres are the specialized chromosomal DNA–protein . Evolution of Telomeres and Telomerase structures that comprise the terminal regions of eukaryotic chromosomes. As discovered through studies of maize and somes. One critical part of this protective function is to fruitfly chromosomes in the 1930s, they are required to provide a means by which the linear chromosomal DNA protect and stabilize the genetic material carried by can be replicated completely, without the loss of terminal eukaryotic chromosomes. Telomeres are dynamic struc- DNA nucleotides from the 5’ end of each strand of this tures, with their terminal DNA being constantly built up DNA. This is necessary to prevent progressive loss of and degraded as dividing cells replicate their chromo- terminal DNA sequences in successive cycles of chromo- somes. One strand of the telomeric DNA is synthesized by somal replication. a specialized ribonucleoprotein reverse transcriptase called telomerase. Telomerase is required for both
    [Show full text]
  • Expression of Telomerase Activity, Human Telomerase RNA, and Telomerase Reverse Transcriptase in Gastric Adenocarcinomas Jinyoung Yoo, M.D., Ph.D., Sonya Y
    Expression of Telomerase Activity, Human Telomerase RNA, and Telomerase Reverse Transcriptase in Gastric Adenocarcinomas Jinyoung Yoo, M.D., Ph.D., Sonya Y. Park, Seok Jin Kang, M.D., Ph.D., Byung Kee Kim, M.D., Ph.D., Sang In Shim, M.D., Ph.D., Chang Suk Kang, M.D., Ph.D. Department of Pathology, St. Vincent’s Hospital, Catholic University, Suwon, South Korea esis of gastric cancer and may reflect, along with Telomerase is an RNA-dependent DNA polymerase enhanced hTR, the malignant potential of the tu- that synthesizes TTAGGG telomeric DNA onto chro- mor. It is noteworthy that methacarn-fixed tissue mosome ends to compensate for sequence loss dur- cannot as yet substitute for the frozen section in the ing DNA replication. It has been detected in 85–90% TRAP assay. of all primary human cancers, implicating that the telomerase seems to be reactivated in tumors and KEY WORDS: hTR, Stomach cancer, Telomerase, that such activity may play a role in the tumorigenic TERT. process. The purpose of this study was to evaluate Mod Pathol 2003;16(7):700–707 telomerase activity, human telomerase RNA (hTR), and telomerase reverse transcriptase (TERT) in Recent studies of stomach cancer have been di- stomach cancer and to determine their potential rected toward gaining a better understanding of relationships to clinicopathologic parameters. Fro- tumor biology. Molecular analysis has suggested zen and corresponding methacarn-fixed paraffin- that alterations in the structures and functions of embedded tissue samples were obtained from 51 oncogenes and tumor suppressor genes, genetic patients with gastric adenocarcinoma and analyzed instability, as well as the acquisition of cell immor- for telomerase activity by using a TRAPeze ELISA tality may be of relevance in the pathogenesis of kit.
    [Show full text]
  • Roles of Telomeres and Telomerase in Cancer, and Advances in Telomerase- Targeted Therapies Mohammad A
    Jafri et al. Genome Medicine (2016) 8:69 DOI 10.1186/s13073-016-0324-x REVIEW Open Access Roles of telomeres and telomerase in cancer, and advances in telomerase- targeted therapies Mohammad A. Jafri1, Shakeel A. Ansari1, Mohammed H. Alqahtani1 and Jerry W. Shay1,2* Abstract Telomeres maintain genomic integrity in normal cells, and their progressive shortening during successive cell divisions induces chromosomal instability. In the large majority of cancer cells, telomere length is maintained by telomerase. Thus, telomere length and telomerase activity are crucial for cancer initiation and the survival of tumors. Several pathways that regulate telomere length have been identified, and genome-scale studies have helped in mapping genes that are involved in telomere length control. Additionally, genomic screening for recurrent human telomerase gene hTERT promoter mutations and mutations in genes involved in the alternative lengthening of telomeres pathway, such as ATRX and DAXX, has elucidated how these genomic changes contribute to the activation of telomere maintenance mechanisms in cancer cells. Attempts have also been made to develop telomere length- and telomerase-based diagnostic tools and anticancer therapeutics. Recent efforts have revealed key aspects of telomerase assembly, intracellular trafficking and recruitment to telomeres for completing DNA synthesis, which may provide novel targets for the development of anticancer agents. Here, we summarize telomere organization and function and its role in oncogenesis. We also highlight genomic mutations that lead to reactivation of telomerase, and mechanisms of telomerase reconstitution and trafficking that shed light on its function in cancer initiation and tumor development. Additionally, recent advances in the clinical development of telomerase inhibitors, as well as potential novel targets, will be summarized.
    [Show full text]
  • (12) Patent Application Publication (10) Pub. No.: US 2003/0082511 A1 Brown Et Al
    US 20030082511A1 (19) United States (12) Patent Application Publication (10) Pub. No.: US 2003/0082511 A1 Brown et al. (43) Pub. Date: May 1, 2003 (54) IDENTIFICATION OF MODULATORY Publication Classification MOLECULES USING INDUCIBLE PROMOTERS (51) Int. Cl." ............................... C12O 1/00; C12O 1/68 (52) U.S. Cl. ..................................................... 435/4; 435/6 (76) Inventors: Steven J. Brown, San Diego, CA (US); Damien J. Dunnington, San Diego, CA (US); Imran Clark, San Diego, CA (57) ABSTRACT (US) Correspondence Address: Methods for identifying an ion channel modulator, a target David B. Waller & Associates membrane receptor modulator molecule, and other modula 5677 Oberlin Drive tory molecules are disclosed, as well as cells and vectors for Suit 214 use in those methods. A polynucleotide encoding target is San Diego, CA 92121 (US) provided in a cell under control of an inducible promoter, and candidate modulatory molecules are contacted with the (21) Appl. No.: 09/965,201 cell after induction of the promoter to ascertain whether a change in a measurable physiological parameter occurs as a (22) Filed: Sep. 25, 2001 result of the candidate modulatory molecule. Patent Application Publication May 1, 2003 Sheet 1 of 8 US 2003/0082511 A1 KCNC1 cDNA F.G. 1 Patent Application Publication May 1, 2003 Sheet 2 of 8 US 2003/0082511 A1 49 - -9 G C EH H EH N t R M h so as se W M M MP N FIG.2 Patent Application Publication May 1, 2003 Sheet 3 of 8 US 2003/0082511 A1 FG. 3 Patent Application Publication May 1, 2003 Sheet 4 of 8 US 2003/0082511 A1 KCNC1 ITREXCHO KC 150 mM KC 2000000 so 100 mM induced Uninduced Steady state O 100 200 300 400 500 600 700 Time (seconds) FIG.
    [Show full text]
  • Supp Table 6.Pdf
    Supplementary Table 6. Processes associated to the 2037 SCL candidate target genes ID Symbol Entrez Gene Name Process NM_178114 AMIGO2 adhesion molecule with Ig-like domain 2 adhesion NM_033474 ARVCF armadillo repeat gene deletes in velocardiofacial syndrome adhesion NM_027060 BTBD9 BTB (POZ) domain containing 9 adhesion NM_001039149 CD226 CD226 molecule adhesion NM_010581 CD47 CD47 molecule adhesion NM_023370 CDH23 cadherin-like 23 adhesion NM_207298 CERCAM cerebral endothelial cell adhesion molecule adhesion NM_021719 CLDN15 claudin 15 adhesion NM_009902 CLDN3 claudin 3 adhesion NM_008779 CNTN3 contactin 3 (plasmacytoma associated) adhesion NM_015734 COL5A1 collagen, type V, alpha 1 adhesion NM_007803 CTTN cortactin adhesion NM_009142 CX3CL1 chemokine (C-X3-C motif) ligand 1 adhesion NM_031174 DSCAM Down syndrome cell adhesion molecule adhesion NM_145158 EMILIN2 elastin microfibril interfacer 2 adhesion NM_001081286 FAT1 FAT tumor suppressor homolog 1 (Drosophila) adhesion NM_001080814 FAT3 FAT tumor suppressor homolog 3 (Drosophila) adhesion NM_153795 FERMT3 fermitin family homolog 3 (Drosophila) adhesion NM_010494 ICAM2 intercellular adhesion molecule 2 adhesion NM_023892 ICAM4 (includes EG:3386) intercellular adhesion molecule 4 (Landsteiner-Wiener blood group)adhesion NM_001001979 MEGF10 multiple EGF-like-domains 10 adhesion NM_172522 MEGF11 multiple EGF-like-domains 11 adhesion NM_010739 MUC13 mucin 13, cell surface associated adhesion NM_013610 NINJ1 ninjurin 1 adhesion NM_016718 NINJ2 ninjurin 2 adhesion NM_172932 NLGN3 neuroligin
    [Show full text]
  • RNA Binding Domain of Telomerase Reverse Transcriptase Cary Lai University of San Francisco, [email protected]
    The University of San Francisco USF Scholarship: a digital repository @ Gleeson Library | Geschke Center Biology Faculty Publications Biology 2001 RNA Binding Domain of Telomerase Reverse Transcriptase Cary Lai University of San Francisco, [email protected] James R. Mitchell Kathleen Collins Follow this and additional works at: http://repository.usfca.edu/biol_fac Part of the Biology Commons Recommended Citation Cary K. Lai, James R. Mitchell, and Kathleen Collins. RNA Binding Domain of Telomerase Reverse Transcriptase. Mol Cell Biol. 2001 Feb; 21(4): 990–1000. This Article is brought to you for free and open access by the Biology at USF Scholarship: a digital repository @ Gleeson Library | Geschke Center. It has been accepted for inclusion in Biology Faculty Publications by an authorized administrator of USF Scholarship: a digital repository @ Gleeson Library | Geschke Center. For more information, please contact [email protected]. MOLECULAR AND CELLULAR BIOLOGY, Feb. 2001, p. 990–1000 Vol. 21, No. 4 0270-7306/01/$04.00ϩ0 DOI: 10.1128/MCB.21.4.990–1000.2001 Copyright © 2001, American Society for Microbiology. All Rights Reserved. RNA Binding Domain of Telomerase Reverse Transcriptase CARY K. LAI, JAMES R. MITCHELL, AND KATHLEEN COLLINS* Division of Biochemistry and Molecular Biology, Department of Molecular and Cell Biology, University of California, Berkeley, California 94720-3204 Received 23 October 2000/Returned for modification 20 November 2000/Accepted 28 November 2000 Telomerase is a ribonucleoprotein reverse transcriptase that extends the ends of chromosomes. The two telomerase subunits essential for catalysis in vitro are the telomerase reverse transcriptase (TERT) and the telomerase RNA. Using truncations and site-specific mutations, we identified sequence elements of TERT and telomerase RNA required for catalytic activity and protein-RNA interaction for Tetrahymena thermophila telo- merase.
    [Show full text]
  • Telomere Shortening and Apoptosis in Telomerase-Inhibited Human Tumor Cells
    Downloaded from genesdev.cshlp.org on September 28, 2021 - Published by Cold Spring Harbor Laboratory Press Telomere shortening and apoptosis in telomerase-inhibited human tumor cells Xiaoling Zhang,1 Vernon Mar,1 Wen Zhou,1 Lea Harrington,2 and Murray O. Robinson1,3 1Department of Cancer Biology, Amgen, Thousand Oaks, California 91320 USA; 2Amgen Institute/Ontario Cancer Institute, Toronto, Ontario M5G2C1 Canada Despite a strong correlation between telomerase activity and malignancy, the outcome of telomerase inhibition in human tumor cells has not been examined. Here, we have addressed the role of telomerase activity in the proliferation of human tumor and immortal cells by inhibiting TERT function. Inducible dominant-negative mutants of hTERT dramatically reduced the level of endogenous telomerase activity in tumor cell lines. Clones with short telomeres continued to divide, then exhibited an increase in abnormal mitoses followed by massive apoptosis leading to the loss of the entire population. This cell death was telomere-length dependent, as cells with long telomeres were viable but exhibited telomere shortening at a rate similar to that of mortal cells. It appears that telomerase inhibition in cells with short telomeres lead to chromosomal damage, which in turn trigger apoptotic cell death. These results provide the first direct evidence that telomerase is required for the maintenance of human tumor and immortal cell viability, and suggest that tumors with short telomeres may be effectively and rapidly killed following telomerase inhibition. [Key Words: TERT; telomere; dominant negative; proliferation; cancer] Received June 4, 1999; revised version accepted August 3, 1999. The termini of most eukaryotic chromosomes are com- TEP1 binds the telomerase RNA and associates with posed of terminal repeats called telomeres.
    [Show full text]
  • Telomerase and Cancer Kirk A
    Telomerase and Cancer Kirk A. Landon - AACR Prize for Basic Cancer Research Lecture Elizabeth H. Blackburn Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, California Telomerase is commonly expressed in human cancer cells. round of replication. Thus, incomplete replication of the Increased telomerase expression produces vulnerability of chromosome ends occurs, which, if left unchecked by any cancer cells, distinguishing them from normal cells in the compensatory mechanism, leads to a problem of maintaining body, although normal cells do also have some active the full-length of chromosomal DNA molecules. The telomerase. Recent studies also suggest that telomerase is chromosome ends become progressively shorter, which was implicated in tumor progression in unexpected ways. These predicted eventually to lead, by some unknown mechanism, to observations lead us to investigate the most efficient means of cells ceasing to divide. The solution to this theoretical inhibiting telomerase in cancer cells. problem was the enzyme telomerase (1). Carol Greider and I identified the telomerase enzyme first in the ciliated A Brief Review of Telomeres and Telomerase protozoan Tetrahymena. We used this organism because it Telomeres, the ends of the chromosomes, are required to has a large number of telomeres and is a relatively rich source protect chromosomal ends. A complex set of biological of telomerase. Telomerase contains an RNA component. The functions is encompassed in the word ‘‘capping’’ of the ends RNA has a short template sequence that is copied into DNA, of the chromosomes. The telomere, after all, represents a DNA which extends, and thus lengthens, the chromosomal DNA. end, which is at the end of the linear chromosomal DNA, but it We were able to show that this also occurs in vivo.
    [Show full text]
  • Mutations in the Telomerase Component NHP2 Cause the Premature Ageing Syndrome Dyskeratosis Congenita
    Mutations in the telomerase component NHP2 cause the premature ageing syndrome dyskeratosis congenita Tom Vulliamy†‡, Richard Beswick†, Michael Kirwan†, Anna Marrone†§, Martin Digweed¶, Amanda Walne†, and Inderjeet Dokal† †Academic Unit of Paediatrics, Institute of Cell and Molecular Science, Barts and the London School of Medicine and Dentistry, London E1 2AT, United Kingdom; and ¶Institut fu¨r Humangenetik, Charite´-Universita¨tsmedizin Berlin, Campus Virchow-Klinikum, 13353 Berlin, Germany Edited by Ernest Beutler, The Scripps Research Institute, La Jolla, CA, and approved April 14, 2008 (received for review January 3, 2008) Dyskeratosis congenita is a premature aging syndrome character- congenita patients have very short telomeres (10, 15), and some ized by muco-cutaneous features and a range of other abnormal- have been shown to have reduced levels of TERC (the RNA ities, including early greying, dental loss, osteoporosis, and malig- component of telomerase) (16, 17). It has been suggested nancy. Dyskeratosis congenita cells age prematurely and have very therefore that dyskeratosis congenita may primarily be a disor- short telomeres. Patients have mutations in genes that encode der of telomere maintenance. The most compelling evidence components of the telomerase complex (dyskerin, TERC, TERT, and supporting this view is that autosomal dominant dyskeratosis NOP10), important in the maintenance of telomeres. Many dys- congenita can result from TERC mutations (18), which cause a keratosis congenita patients remain uncharacterized. Here, we reduction in telomerase activity and give rise to disease via describe the analysis of two other proteins, NHP2 and GAR1, that haploinsufficiency (19–21). Heterozygous missense mutations in together with dyskerin and NOP10 are key components of telom- the reverse transcriptase component of telomerase (TERT) that erase and small nucleolar ribonucleoprotein (snoRNP) complexes.
    [Show full text]
  • (12) Patent Application Publication (10) Pub. No.: US 2014/0079836A1 Mcdaniel (43) Pub
    US 20140079836A1 (19) United States (12) Patent Application Publication (10) Pub. No.: US 2014/0079836A1 McDaniel (43) Pub. Date: Mar. 20, 2014 (54) METHODS AND COMPOSITIONS FOR (52) U.S. Cl. ALTERING HEALTH, WELLBEING AND CPC ............... A61K 36/74 (2013.01); A61 K3I/122 LIFESPAN (2013.01) USPC ............. 424/777; 514/690: 435/375; 506/16; (71) Applicant: LifeSpan Extension, LLC, Virginia 435/6.12 Beach, VA (US) (72) Inventor: David H. McDaniel, Virginia Beach, VA (57) ABSTRACT (US) Described herein are the results of comprehensive genetic (73) Assignee: LifeSpan Extension, LLC expression and other molecular analysis p the effect s anti oxidants on biological systems, including specifically differ (21) Appl. No.: 14/084,553 ent human cells. Based on these analyses, methods and com (22) Filed: Nov. 19, 2013 positions are described for modifying or influencing the lifespan of cells, tissues, organs, and organisms. In various Related U.S. Application Data embodiments, there are provided methods for modulating the activity of the gene maintenance process in order to influence (60) Continuation of application No. 13/898.307, filed on the length and/or structural integrity of the telomere in living May 20, 2013, which is a division of application No. cells, as well as methods for modulating the rate/efficiency of 12/629,040, filed on Dec. 1, 2009, now abandoned. the cellular respiration provided by the mitochondria, mito (60) Provisional application No. 61/118,945, filed on Dec. chondrial biogenesis, and maintenance of the mitochondrial 1, 2008. membrane potential. Exemplary lifespan altering compounds include natural and synthetic antioxidants, such as plant anti Publication Classification oxidant and polyphenol compounds derived from coffee cherry, tea, berry, and so forth, including but not limited to (51) Int.
    [Show full text]
  • RNA Recognition by the DNA End-Binding Ku Heterodimer
    Downloaded from rnajournal.cshlp.org on October 3, 2021 - Published by Cold Spring Harbor Laboratory Press RNA recognition by the DNA end-binding Ku heterodimer ANDREW B. DALBY, KAREN J. GOODRICH, JENNIFER S. PFINGSTEN,1 and THOMAS R. CECH2 Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, University of Colorado BioFrontiers Institute, Boulder, Colorado 80309-0596, USA ABSTRACT Most nucleic acid-binding proteins selectively bind either DNA or RNA, but not both nucleic acids. The Saccharomyces cerevisiae Ku heterodimer is unusual in that it has two very different biologically relevant binding modes: (1) Ku is a sequence-nonspecific double-stranded DNA end-binding protein with prominent roles in nonhomologous end-joining and telomeric capping, and (2) Ku associates with a specific stem–loop of TLC1, the RNA subunit of budding yeast telomerase, and is necessary for proper nuclear localization of this ribonucleoprotein enzyme. TLC1 RNA-binding and dsDNA-binding are mutually exclusive, so they may be mediated by the same site on Ku. Although dsDNA binding by Ku is well studied, much less is known about what features of an RNA hairpin enable specific recognition by Ku. To address this question, we localized the Ku-binding site of the TLC1 hairpin with single-nucleotide resolution using phosphorothioate footprinting, used chemical modification to identify an unpredicted motif within the hairpin secondary structure, and carried out mutagenesis of the stem–loop to ascertain the critical elements within the RNA that permit Ku binding. Finally, we provide evidence that the Ku-binding site is present in additional budding yeast telomerase RNAs and discuss the possibility that RNA binding is a conserved function of the Ku heterodimer.
    [Show full text]
  • Telomere Maintenance Pathway Activity Analysis Enables Tissue- and Gene-Level Inferences
    bioRxiv preprint doi: https://doi.org/10.1101/2021.02.01.429081; this version posted February 2, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. Telomere maintenance pathway activity analysis enables tissue- and gene-level inferences Lilit Nersisyan1,2*, Arman Simonyan1, Hans Binder3, Arsen Arakelyan1,2 1 Bioinformatics Group, Institute of Molecular Biology, National Academy of Sciences, Yerevan, Armenia 2 Pathverse, LLC, Yerevan, Armenia 3 Interdisciplinary Center for Bioinformatics, University of Leipzig, Leipzig, Germany * Correspondence: Lilit Nersisyan Keywords: telomere maintenance mechanisms, telomerase, alternative lengthening of telomeres, pathway signal flow, testis ABSTRACT Telomere maintenance is one of the mechanisms ensuring indefinite divisions of cancer and stem cells. Good understanding of telomere maintenance mechanisms (TMM) is important for studying cancers and designing therapies. However, molecular factors triggering selective activation of either the telomerase dependent (TEL) or the alternative lengthening of telomeres (ALT) pathway are poorly understood. In addition, more accurate and easy-to-use methodologies are required for TMM phenotyping. In this study, we have performed literature based reconstruction of signaling pathways for the ALT and TEL TMMs. Gene expression data were used for computational assessment of TMM pathway activities and compared with experimental assays for TEL and ALT. Explicit consideration of pathway topology makes bioinformatics analysis more informative compared to computational methods based on simple summary measures of gene expression. Application to healthy human tissues showed high ALT and TEL pathway activities in testis, and identified genes and pathways that may trigger TMM activation.
    [Show full text]