scholarly journals TIN2 functions with TPP1/POT1 to stimulate telomerase processivity

2018 ◽  
Author(s):  
Alexandra M. Pike ◽  
Margaret A. Strong ◽  
John Paul T. Ouyang ◽  
Carla J. Connelly ◽  
Carol W. Greider
Keyword(s):  
Telomere Length ◽  
Telomerase Activity ◽  
Human Cells ◽  
Scaffolding Protein ◽  
Short Telomere ◽  
Gene Encoding ◽  
Important Regulator

AbstractTelomere length maintenance is crucial for cells that divide many times. TIN2 is an important regulator of telomere length, and mutations in TINF2, the gene encoding TIN2, cause short telomere syndromes. While the genetics underscore the importance of TIN2, the mechanism through which TIN2 regulates telomere length remains unclear. Here, we characterize the effects of TIN2 on telomerase activity. We identified a new isoform in human cells, TIN2M, that is expressed at similar levels to previously studied TIN2 isoforms. Additionally, we found that all three TIN2 isoforms stimulated telomerase processivity beyond the previously characterized stimulation by TPP1/POT1. Mutations in the TPP1 TEL-patch abrogated this stimulation, implicating TIN2 as a component of the TPP1/POT1 processivity complex. All three TIN2 isoforms localized to telomeres in vivo but had distinct effects on telomere length, suggesting they are functionally distinct. These data contrast previous descriptions of TIN2 a simple scaffolding protein, showing that TIN2 isoforms directly regulate telomerase.

scholarly journals TIN2 Functions with TPP1/POT1 To Stimulate Telomerase Processivity

2019 ◽  
Vol 39 (21) ◽  
Author(s):  
Alexandra M. Pike ◽  
Margaret A. Strong ◽  
John Paul T. Ouyang ◽  
Carol W. Greider
Keyword(s):  
Telomere Length ◽  
Telomerase Activity ◽  
Human Cells ◽  
Short Telomere ◽  
Gene Encoding ◽  
Important Regulator

ABSTRACT TIN2 is an important regulator of telomere length, and mutations in TINF2, the gene encoding TIN2, cause short-telomere syndromes. While the genetics underscore the importance of TIN2, the mechanism through which TIN2 regulates telomere length remains unclear. Here, we tested the effects of human TIN2 on telomerase activity. We identified a new isoform in human cells, TIN2M, that is expressed at levels similar to those of previously studied TIN2 isoforms. All three TIN2 isoforms localized to and maintained telomere integrity in vivo, and localization was not disrupted by telomere syndrome mutations. Using direct telomerase activity assays, we discovered that TIN2 stimulated telomerase processivity in vitro. All of the TIN2 isoforms stimulated telomerase to similar extents. Mutations in the TPP1 TEL patch abrogated this stimulation, suggesting that TIN2 functions with TPP1/POT1 to stimulate telomerase processivity. We conclude from our data and previously published work that TIN2/TPP1/POT1 is a functional shelterin subcomplex.

33 TELOMERASE ACTIVITIES IN CLONED BEAGLE DOGS

2015 ◽  
Vol 27 (1) ◽  
pp. 109
Author(s):  
G. A. Kim ◽  
H. J. Oh ◽  
M. J. Kim ◽  
Y. K. Jo ◽  
E. M. N. Setyawan ◽  
...  
Keyword(s):  
Telomere Length ◽  
Donor Cell ◽  
Telomerase Activity ◽  
Physiological Age ◽  
Biological Aging ◽  
Amplification Protocol ◽  
Donor Cells ◽  
Activity Measurements ◽  
Natural Breeding

Telomerase is important ribonucleoprotein for restoring telomere length from its own RNA template. Regarding cloned animals derived from somatic cell nuclear transfer (SCNT), interesting questions have been raised about whether the cloning process restores cellular telomerase activity undergone by their donor cells. The present study was conducted to determine the effects of cloning on telomerase activity in the dog and normality of telomerase activity in cloned dogs. Focusing our attention on differences in telomerase activity depending on the age, we analysed telomerase activity in dogs produced by natural breeding of various ages. Comparison of the telomerase activities of cloned dogs and those of dogs produced by natural breeding was also performed. For SCNT, 2 cell donors, 7- and 9-year-old beagles, were used and donor cells were isolated from ear skin. After establishing donor cell lines, the enucleated canine in vivo-matured oocytes and the cells were injected and fused by electrofusion. After 30 days from embryo transfer, pregnancy diagnosis was performed and 7 cloned dogs were produced on the due date. For standardization of telomerase activity in beagles produced by natural breeding, blood of total 14 dogs at each age (10 months, 20 months, 5, 7, and 8 years old) were collected and telomerase activity was measured by the telomeric repeat amplification protocol (TRAP) assay. Telomerase activity measurements of at least 6 replications in each dog were performed. For statistical analysis, one-way ANOVA with Dunn's Multiple Comparison Test was used. Significant differences in telomerase activity were observed between the blood of cloned and donor dogs. It was shown that mean telomerase activities were decreased according to biological aging with significances. Mean telomerase activities in 10 cloned dogs were higher than those of a donor dog. Cloned dogs also showed similar levels of telomerase activities as their age-matched natural bred dogs, suggesting that they are within the variation in normal dogs. These observations indicate that the cloning process restores the telomerase activity in the dog. Thus, complex regulation of telomerase activity during nuclear reprogramming may regulate and be involved in telomerase activity in cloned dogs. It remains to be determined whether telomere length is correlated with telomerase activity and if it accurately reflects the physiological age of cloned dogs.This study was supported by IPET (#311062–04–2-SB010), RDA (PJ008975022013), Research Institute for Veterinary Science, the BK21 program, Nestle Purina Korea, and TS Corporation.

scholarly journals Telomere length: how the length makes a difference

2020 ◽  
Vol 47 (9) ◽  
pp. 7181-7188 ◽  
Author(s):  
M. Lulkiewicz ◽  
J. Bajsert ◽  
P. Kopczynski ◽  
W. Barczak ◽  
B. Rubis
Keyword(s):  
Telomere Length ◽  
Meta Analysis ◽  
Telomerase Activity ◽  
Human Cells ◽  
Attrition Rate ◽  
Severe Damage ◽  
Telomere Attrition ◽  
Adult Men ◽  
Cell Life ◽  
Real Value

Abstract Telomerase is perceived as an immortality enzyme that might provide longevity to cells and whole organisms. Importantly, it is generally inactive in most somatic cells of healthy, adult men. Consequently, its substrates, i.e. telomeres, get shorter in most human cells with time. Noteworthy, cell life limitation due to telomere attrition during cell divisions, may not be as bad as it looks since longer cell life means longer exposition to harmful factors. Consequently, telomere length (attrition rate) becomes a factor that is responsible for inducing the signaling that leads to the elimination of cells that lived long enough to acquire severe damage. It seems that telomere length that depends on many different factors (including telomerase activity but also genetic factors, a hormonal profile that reflects sex, etc.) might become a useful marker of aging and exposition to stress. Thus in the current paper, we review the factors that affect telomere length in human cells focusing on sex that all together with different environmental and hormonal regulations as well as parental aspect affect telomere attrition rate. We also raise some limitations in the assessment of telomere length that hinders a trustworthy meta-analysis that might lead to acknowledgment of the real value of this parameter.

scholarly journals Yeast Est2p Affects Telomere Length by Influencing Association of Rap1p with Telomeric Chromatin

2008 ◽  
Vol 28 (7) ◽  
pp. 2380-2390 ◽  
Author(s):  
Hong Ji ◽  
Christopher J. Adkins ◽  
Bethany R. Cartwright ◽  
Katherine L. Friedman
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Telomere Length ◽  
Specific Binding ◽  
Telomerase Activity ◽  
Negative Regulator ◽  
Wild Type ◽  
Telomeric Dna ◽  
Telomere Length Homeostasis

ABSTRACT In Saccharomyces cerevisiae, the sequence-specific binding of the negative regulator Rap1p provides a mechanism to measure telomere length: as the telomere length increases, the binding of additional Rap1p inhibits telomerase activity in cis. We provide evidence that the association of Rap1p with telomeric DNA in vivo occurs in part by sequence-independent mechanisms. Specific mutations in EST2 (est2-LT) reduce the association of Rap1p with telomeric DNA in vivo. As a result, telomeres are abnormally long yet bind an amount of Rap1p equivalent to that observed at wild-type telomeres. This behavior contrasts with that of a second mutation in EST2 (est2-up34) that increases bound Rap1p as expected for a strain with long telomeres. Telomere sequences are subtly altered in est2-LT strains, but similar changes in est2-up34 telomeres suggest that sequence abnormalities are a consequence, not a cause, of overelongation. Indeed, est2-LT telomeres bind Rap1p indistinguishably from the wild type in vitro. Taken together, these results suggest that Est2p can directly or indirectly influence the binding of Rap1p to telomeric DNA, implicating telomerase in roles both upstream and downstream of Rap1p in telomere length homeostasis.

Telomerase Activity and Telomere Length of CD4+CD25+ Regulatory T-Cells under Conditions of In Vitro and In Vivo Expansion.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 3857-3857
Author(s):  
Dominik G.F. Wolf ◽  
Anna M. Wolf ◽  
Christian Koppelstaetter ◽  
Holger F. Rumpold ◽  
Gert Mayer ◽  
...  
Keyword(s):  
T Cells ◽  
Regulatory T Cells ◽  
Telomere Length ◽  
Cancer Patients ◽  
Telomerase Activity ◽  
Telomere Maintenance ◽  
Healthy Human ◽  
Telomere Shortening

Abstract The expandability of CD4+CD25+ regulatory T-cells (Treg) has been shown in vitro and in vivo. Activation of telomerase activity is a prerequisite for clonal expansion and telomere maintenance in T-cells. There is currently no data available on the expression and function of telomerase in proliferating Treg. Analyses of telomere length by flow-FISH, real-time PCR and Southern blotting revealed that Treg isolated from healthy human volunteers have significantly shortened telomeres when compared to CD4+CD25− T-cells. However, telomere length is not further shortened in Treg isolated from the peripheral blood of cancer patients, despite the observation that the regulatory T-cell pool of these patients was significantly enlarged. To gain further insight into maintenance of telomere length of Treg, we induced in vitro proliferation of Treg by stimulation with anti-CD3 and IL-2. This led to a rapid increase of telomerase activity, as determined by PCR-ELISA. However, when we focused on the proliferating fraction of Treg using a sorting strategy based on the dilution of CFSE, we could show a significant telomere shortening in Treg with high proliferative and immmuno-suppressive capacity. Of note, proliferating CFSElow Treg are characterized by high telomerase activity, which however seems to be insufficient to avoid further telomere shortening under conditions of strong in vitro stimulation. In contrast, under conditions of in vivo expansion of Treg in cancer patients, the induction of telomerase activity is likely to compensate for further telomere erosion. These data might be of importance when considering the application of in vitro expanded Treg for the treatment of GvHD or autoimmune diseases, as telomere shortening might be associated with genomic instability.

scholarly journals Neisseria meningitidis Polynucleotide Phosphorylase Affects Aggregation, Adhesion, and Virulence

2016 ◽  
Vol 84 (5) ◽  
pp. 1501-1513 ◽  
Author(s):  
Jakob Engman ◽  
Aurel Negrea ◽  
Sara Sigurlásdóttir ◽  
Miriam Geörg ◽  
Jens Eriksson ◽  
...  
Keyword(s):  
Neisseria Meningitidis ◽  
Posttranslational Modifications ◽  
Human Cells ◽  
Bacterial Attachment ◽  
Polynucleotide Phosphorylase ◽  
Gene Encoding ◽  
Content Type ◽  
Type Iv ◽  
Transcriptional Changes

Neisseria meningitidisautoaggregation is an important step during attachment to human cells. Aggregation is mediated by type IV pili and can be modulated by accessory pilus proteins, such as PilX, and posttranslational modifications of the major pilus subunit PilE. The mechanisms underlying the regulation of aggregation remain poorly characterized. Polynucleotide phosphorylase (PNPase) is a 3′–5′ exonuclease that is involved in RNA turnover and the regulation of small RNAs. In this study, we biochemically confirm that NMC0710 is theN. meningitidisPNPase, and we characterize its role inN. meningitidispathogenesis. We show that deletion of the gene encoding PNPase leads to hyperaggregation and increased adhesion to epithelial cells. The aggregation induced was found to be dependent on pili and to be mediated by excessive pilus bundling. PNPase expression was induced following bacterial attachment to human cells. Deletion of PNPase led to global transcriptional changes and the differential regulation of 469 genes. We also demonstrate that PNPase is required for full virulence in anin vivomodel ofN. meningitidisinfection. The present study shows that PNPase negatively affects aggregation, adhesion, and virulence inN. meningitidis.

scholarly journals Vault Poly(ADP-Ribose) Polymerase Is Associated with Mammalian Telomerase and Is Dispensable for Telomerase Function and Vault Structure In Vivo

2004 ◽  
Vol 24 (12) ◽  
pp. 5314-5323 ◽  
Author(s):  
Yie Liu ◽  
Bryan E. Snow ◽  
Valerie A. Kickhoefer ◽  
Natalie Erdmann ◽  
Wen Zhou ◽  
...  
Keyword(s):  
Telomere Length ◽  
Telomerase Activity ◽  
Molecular Assembly ◽  
Cellular Functions ◽  
Telomere Function ◽  
Minor Protein ◽  
The Stability ◽  
A Minor

ABSTRACT Vault poly(ADP-ribose) polymerase (VPARP) was originally identified as a minor protein component of the vault ribonucleoprotein particle, which may be involved in molecular assembly or subcellular transport. In addition to the association of VPARP with the cytoplasmic vault particle, subpopulations of VPARP localize to the nucleus and the mitotic spindle, indicating that VPARP may have other cellular functions. We found that VPARP was associated with telomerase activity and interacted with exogenously expressed telomerase-associated protein 1 (TEP1) in human cells. To study the possible role of VPARP in telomerase and vault complexes in vivo, mVparp-deficient mice were generated. Mice deficient in mVparp were viable and fertile for up to five generations, with no apparent changes in telomerase activity or telomere length. Vaults purified from mVparp-deficient mouse liver appeared intact, and no defect in association with other vault components was observed. Mice deficient in mTep1, whose disruption alone does not affect telomere function but does affect the stability of vault RNA, showed no additional telomerase or telomere-related phenotypes when the mTep1 deficiency was combined with an mVparp deficiency. These data suggest that murine mTep1 and mVparp, alone or in combination, are dispensable for normal development, telomerase catalysis, telomere length maintenance, and vault structure in vivo.

scholarly journals Telomerase-Associated Protein TEP1 Is Not Essential for Telomerase Activity or Telomere Length Maintenance In Vivo

2000 ◽  
Vol 20 (21) ◽  
pp. 8178-8184 ◽  
Author(s):  
Yie Liu ◽  
Bryan E. Snow ◽  
M. Prakash Hande ◽  
Gabriela Baerlocher ◽  
Valerie A. Kickhoefer ◽  
...  
Keyword(s):  
Telomere Length ◽  
Rna Binding ◽  
Es Cells ◽  
Embryonic Stem ◽  
Telomerase Activity ◽  
Telomerase Rna ◽  
Wild Type ◽  
Rnp Complex ◽  
Successive Generations

ABSTRACT TEP1 is a mammalian telomerase-associated protein with similarity to the Tetrahymena telomerase protein p80. Like p80, TEP1 is associated with telomerase activity and the telomerase reverse transcriptase, and it specifically interacts with the telomerase RNA. To determine the role of mTep1 in telomerase function in vivo, we generated mouse embryonic stem (ES) cells and mice lacking mTep1. ThemTep1-deficient (mTep1 −/−) mice were viable and were bred for seven successive generations with no obvious phenotypic abnormalities. All murine tissues frommTep1 −/− mice possessed a level of telomerase activity comparable to that in wild-type mice. In addition, analysis of several tissues that normally lack telomerase activity revealed no reactivation of telomerase activity in mTep1 −/− mice. Telomere length, even in later generations ofmTep1 −/− mice, was equivalent to that in wild-type animals. ES cells deficient in mTep1 also showed no detectable alteration in telomerase activity or telomere length with increased passage in culture. Thus, mTep1 appears to be completely dispensable for telomerase function in vivo. Recently, TEP1 has been identified within a second ribonucleoprotein (RNP) complex, the vault particle. TEP1 can also specifically bind to a small RNA, vRNA, which is associated with the vault particle and is unrelated in sequence to mammalian telomerase RNA. These results reveal that TEP1 is an RNA binding protein that is not restricted to the telomerase complex and that TEP1 plays a redundant role in the assembly or localization of the telomerase RNP in vivo.

scholarly journals Exploring the Interplay of Telomerase Reverse Transcriptase and β-Catenin in Hepatocellular Carcinoma

Cancers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 4202
Author(s):  
Srishti Kotiyal ◽  
Kimberley Jane Evason
Keyword(s):  
Hepatocellular Carcinoma ◽  
Stem Cells ◽  
Reverse Transcriptase ◽  
Target Genes ◽  
Telomerase Activity ◽  
Telomerase Reverse Transcriptase ◽  
Gene Encoding ◽  
Activating Mutations ◽  
Proliferation And Differentiation

Hepatocellular carcinoma (HCC) is one of the deadliest human cancers. Activating mutations in the telomerase reverse transcriptase (TERT) promoter (TERTp) and CTNNB1 gene encoding β-catenin are widespread in HCC (~50% and ~30%, respectively). TERTp mutations are predicted to increase TERT transcription and telomerase activity. This review focuses on exploring the role of TERT and β-catenin in HCC and the current findings regarding their interplay. TERT can have contradictory effects on tumorigenesis via both its canonical and non-canonical functions. As a critical regulator of proliferation and differentiation in progenitor and stem cells, activated β-catenin drives HCC; however, inhibiting endogenous β-catenin can also have pro-tumor effects. Clinical studies revealed a significant concordance between TERTp and CTNNB1 mutations in HCC. In stem cells, TERT acts as a co-factor in β-catenin transcriptional complexes driving the expression of WNT/β-catenin target genes, and β-catenin can bind to the TERTp to drive its transcription. A few studies have examined potential interactions between TERT and β-catenin in HCC in vivo, and their results suggest that the coexpression of these two genes promotes hepatocarcinogenesis. Further studies are required with vertebrate models to better understand how TERT and β-catenin influence hepatocarcinogenesis.

scholarly journals Expression of Telomerase RNA Template, but Not Telomerase Reverse Transcriptase, Is Limiting for Telomere Length Maintenance In Vivo

2004 ◽  
Vol 24 (16) ◽  
pp. 7024-7031 ◽  
Author(s):  
Y. Jeffrey Chiang ◽  
Michael T. Hemann ◽  
Karen S. Hathcock ◽  
Lino Tessarollo ◽  
Lionel Feigenbaum ◽  
...  
Keyword(s):  
Reverse Transcriptase ◽  
Telomere Length ◽  
Telomerase Activity ◽  
Telomere Maintenance ◽  
Gene Copy ◽  
Telomerase Reverse Transcriptase ◽  
Telomerase Rna ◽  
Wild Type ◽  
Telomere Elongation

ABSTRACT Telomerase consists of two essential components, the telomerase RNA template (TR) and telomerase reverse transcriptase (TERT). The haplo-insufficiency of TR was recently shown to cause one form of human dyskeratosis congenita, an inherited disease marked by abnormal telomere shortening. Consistent with this finding, we recently reported that mice heterozygous for inactivation of mouse TR exhibit a similar haplo-insufficiency and are deficient in the ability to elongate telomeres in vivo. To further assess the genetic regulation of telomerase activity, we have compared the abilities of TR-deficient and TERT-deficient mice to maintain or elongate telomeres in interspecies crosses. Homozygous TERT knockout mice had no telomerase activity and failed to maintain telomere length. In contrast, TERT+/− heterozygotes had no detectable defect in telomere elongation compared to wild-type controls, whereas TR+/− heterozygotes were deficient in telomere elongation. Levels of TERT mRNA in heterozygous mice were one-third to one-half the levels expressed in wild-type mice, similar to the reductions in telomerase RNA observed in TR heterozygotes. These findings indicate that both TR and TERT are essential for telomere maintenance and elongation but that gene copy number and transcriptional regulation of TR, but not TERT, are limiting for telomerase activity under the in vivo conditions analyzed.

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