TheC. elegansmaternal-effect geneclk-2is essential for embryonic development, encodes a protein homologous to yeast Tel2p and affects telomere length

Development ◽  
2001 ◽  
Vol 128 (20) ◽  
pp. 4045-4055 ◽  
Author(s):  
Claire Bénard ◽  
Brent McCright ◽  
Yue Zhang ◽  
Stephanie Felkai ◽  
Bernard Lakowski ◽  
...  
Keyword(s):  
Embryonic Development ◽  
Telomere Length ◽  
Positional Cloning ◽  
Time Window ◽  
Temperature Sensitive ◽  
Dna Repeats ◽  
Telomeric Dna ◽  
C Elegans ◽  
And Behavior

The Caenorhabditis elegans maternal-effect clk genes are involved in the temporal control of development and behavior. We report the genetic and molecular characterization of clk-2. A temperature-sensitive mutation in the gene clk-2 affects embryonic and post-embryonic development, reproduction, and rhythmic behaviors. Yet, virtually all phenotypes are fully maternally rescued. Embryonic development strictly requires the activity of maternal clk-2 during a narrow time window between oocyte maturation and the two- to four-cell embryonic stage. Positional cloning of clk-2 reveals that it encodes a protein homologous to S. cerevisiae Tel2p. In yeast, the gene TEL2 regulates telomere length and participates in gene silencing at subtelomeric regions. In C. elegans, clk-2 mutants have elongated telomeres, and clk-2 overexpression can lead to telomere shortening. Tel2p has been reported to bind to telomeric DNA repeats in vitro. However, we find that a functional CLK-2::GFP fusion protein is cytoplasmic in worms. We discuss how the phenotype of clk-2 mutants could be the result of altered patterns of gene expression.

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.

scholarly journals Functional Diversification of Replication Protein A Paralogs and Telomere Length Maintenance in Arabidopsis

Genetics ◽  
2020 ◽  
Vol 215 (4) ◽  
pp. 989-1002
Author(s):  
Behailu B. Aklilu ◽  
François Peurois ◽  
Carole Saintomé ◽  
Kevin M. Culligan ◽  
Daniela Kobbe ◽  
...  
Keyword(s):  
Homologous Recombination ◽  
Telomere Length ◽  
Protein A ◽  
Replication Protein A ◽  
Telomerase Activity ◽  
Replication Protein ◽  
Telomeric Dna ◽  
Telomere Shortening ◽  
Replication Group

Replication protein A (RPA) is essential for many facets of DNA metabolism. The RPA gene family expanded in Arabidopsis thaliana with five phylogenetically distinct RPA1 subunits (RPA1A-E), two RPA2 (RPA2A and B), and two RPA3 (RPA3A and B). RPA1 paralogs exhibit partial redundancy and functional specialization in DNA replication (RPA1B and RPA1D), repair (RPA1C and RPA1E), and meiotic recombination (RPA1A and RPA1C). Here, we show that RPA subunits also differentially impact telomere length set point. Loss of RPA1 resets bulk telomeres at a shorter length, with a functional hierarchy for replication group over repair and meiosis group RPA1 subunits. Plants lacking RPA2A, but not RPA2B, harbor short telomeres similar to the replication group. Telomere shortening does not correlate with decreased telomerase activity or deprotection of chromosome ends in rpa mutants. However, in vitro assays show that RPA1B2A3B unfolds telomeric G-quadruplexes known to inhibit replications fork progression. We also found that ATR deficiency can partially rescue short telomeres in rpa2a mutants, although plants exhibit defects in growth and development. Unexpectedly, the telomere shortening phenotype of rpa2a mutants is completely abolished in plants lacking the RTEL1 helicase. RTEL1 has been implicated in a variety of nucleic acid transactions, including suppression of homologous recombination. Thus, the lack of telomere shortening in rpa2a mutants upon RTEL1 deletion suggests that telomere replication defects incurred by loss of RPA may be bypassed by homologous recombination. Taken together, these findings provide new insight into how RPA cooperates with replication and recombination machinery to sustain telomeric DNA.

scholarly journals Murine Pif1 Interacts with Telomerase and Is Dispensable for Telomere Function In Vivo

2006 ◽  
Vol 27 (3) ◽  
pp. 1017-1026 ◽  
Author(s):  
Bryan E. Snow ◽  
Maria Mateyak ◽  
Jana Paderova ◽  
Andrew Wakeham ◽  
Caterina Iorio ◽  
...  
Keyword(s):  
Telomere Length ◽  
Chromosomal Rearrangements ◽  
Dna Helicase ◽  
Negative Regulator ◽  
Wild Type ◽  
Genetic Redundancy ◽  
Telomeric Dna ◽  
Dna Helicases

ABSTRACT Pif1 is a 5′-to-3′ DNA helicase critical to DNA replication and telomere length maintenance in the budding yeast Saccharomyces cerevisiae. ScPif1 is a negative regulator of telomeric repeat synthesis by telomerase, and recombinant ScPif1 promotes the dissociation of the telomerase RNA template from telomeric DNA in vitro. In order to dissect the role of mPif1 in mammals, we cloned and disrupted the mPif1 gene. In wild-type animals, mPif1 expression was detected only in embryonic and hematopoietic lineages. mPif1 − / − mice were viable at expected frequencies, displayed no visible abnormalities, and showed no reproducible alteration in telomere length in two different null backgrounds, even after several generations. Spectral karyotyping of mPif1 − / − fibroblasts and splenocytes revealed no significant change in chromosomal rearrangements. Furthermore, induction of apoptosis or DNA damage revealed no differences in cell viability compared to what was found for wild-type fibroblasts and splenocytes. Despite a novel association of mPif1 with telomerase, mPif1 did not affect the elongation activity of telomerase in vitro. Thus, in contrast to what occurs with ScPif1, murine telomere homeostasis or genetic stability does not depend on mPif1, perhaps due to fundamental differences in the regulation of telomerase and/or telomere length between mice and yeast or due to genetic redundancy with other DNA helicases.

scholarly journals Seryl tRNA synthetase cooperates with POT1 to regulate telomere length and cellular senescence

2019 ◽  
Vol 4 (1) ◽  
Author(s):  
Yingxi Li ◽  
Xiyang Li ◽  
Mei Cao ◽  
Yuke Jiang ◽  
Jie Yan ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Telomere Length ◽  
Cellular Senescence ◽  
Direct Interaction ◽  
Causative Factor ◽  
Trna Synthetase ◽  
Dna Repeats ◽  
Telomeric Dna ◽  
Trna Synthetases ◽  
Regulate Telomere Length

AbstractDeregulated telomere length is a causative factor in many physiological and pathological processes, including aging and cancer. Many studies focusing on telomeres have revealed important roles for cooperation between the Shelterin protein complex and telomerase in maintaining telomere length. However, it remains largely unknown whether and how aging-related stresses, such as deregulated protein homeostasis, impact telomere length. Here, we explored the possible roles of aminoacyl tRNA synthetases (AARSs), key enzymes catalyzing the first reactions in protein synthesis, in regulating telomere length and aging. We selected seryl tRNA synthetase (SerRS) since our previous studies discovered expanded functions of SerRS in the nucleus in addition to its canonical cytoplasmic role in protein synthesis. In this study, we revealed that overexpression of SerRS promoted cellular senescence and inhibited the growth of cervical tumor xenografts in mice by triggering the senescence of tumor cells. In the nucleus, SerRS directly bound to telomeric DNA repeats and tethered more POT1 proteins to telomeres through a direct interaction between the UNE-S domain of SerRS and the OB1 domain of POT1. We further demonstrated that SerRS-induced enrichment of POT1 prevented the recruitment of telomerase to telomeres, resulting in progressive telomere shortening. Our data suggested a possible molecular link between protein synthesis and telomere length control, the deregulation of which may be associated with aging and cancer.

scholarly journals Alterations of DNA and Chromatin Structures at Telomeres and Genetic Instability in Mouse Cells Defective in DNA Polymerase α

2005 ◽  
Vol 25 (24) ◽  
pp. 11073-11088 ◽  
Author(s):  
Mirai Nakamura ◽  
Akira Nabetani ◽  
Takeshi Mizuno ◽  
Fumio Hanaoka ◽  
Fuyuki Ishikawa
Keyword(s):  
Telomere Length ◽  
Dna Polymerase ◽  
Temperature Sensitive ◽  
Telomeric Dna ◽  
Dna Polymerase Α ◽  
Genome Wide ◽  
Associated Proteins ◽  
Mouse Cells ◽  
The Impact ◽  
Lagging Strand

ABSTRACT Telomere length is controlled by a homeostatic mechanism that involves telomerase, telomere-associated proteins, and conventional replication machinery. Specifically, the coordinated actions of the lagging strand synthesis and telomerase have been argued. Although DNA polymerase α, an enzyme important for the lagging strand synthesis, has been indicated to function in telomere metabolism in yeasts and ciliates, it has not been characterized in higher eukaryotes. Here, we investigated the impact of compromised polymerase α activity on telomeres, using tsFT20 mouse mutant cells harboring a temperature-sensitive polymerase α mutant allele. When polymerase α was temperature-inducibly inactivated, we observed sequential events that included an initial extension of the G-tail followed by a marked increase in the overall telomere length occurring in telomerase-independent and -dependent manners, respectively. These alterations of telomeric DNA were accompanied by alterations of telomeric chromatin structures as revealed by quantitative chromatin immunoprecipitation and immunofluorescence analyses of TRF1 and POT1. Unexpectedly, polymerase α inhibition resulted in a significantly high incidence of Robertsonian chromosome fusions without noticeable increases in other types of chromosomal aberrations. These results indicate that although DNA polymerase α is essential for genome-wide DNA replication, hypomorphic activity leads to a rather specific spectrum of chromosomal abnormality.

scholarly journals The genetic basis of natural variation in C. elegans telomere length

2016 ◽  
Author(s):  
D.C. Cook ◽  
S. Zdraljevic ◽  
R.E. Tanny ◽  
B. Seo ◽  
D.D. Riccardi ◽  
...  
Keyword(s):  
Telomere Length ◽  
Natural Variation ◽  
Genome Instability ◽  
Length Variation ◽  
Genetic Determinants ◽  
Telomeric Dna ◽  
C Elegans ◽  
Offspring Production ◽  
Telomere Capping ◽  
Organismal Fitness

AbstractTelomeres are involved in the maintenance of chromosomes and the prevention of genome instability. Despite this central importance, significant variation in telomere length has been observed in a variety of organisms. The genetic determinants of telomere-length variation and their effects on organismal fitness are largely unexplored. Here, we describe natural variation in telomere length across the Caenorhabditis elegans species. We identify a large-effect variant that contributes to differences in telomere length. The variant alters the conserved oligosaccharide/oligonucleotide-binding fold of POT-2, a homolog of a human telomere-capping shelterin complex subunit. Mutations within this domain likely reduce the ability of POT-2 to bind telomeric DNA, thereby increasing telomere length. We find that telomere-length variation does not correlate with offspring production or longevity in C. elegans wild isolates, suggesting that naturally long telomeres play a limited role in modifying fitness phenotypes in C. elegans.

scholarly journals Universal assay for measuring vertebrate telomeres by real-time quantitative PCR

2019 ◽  
Author(s):  
Stephanie F Hudon ◽  
Esteban Palencia Hurtado ◽  
James D. Beck ◽  
Steven J. Burden ◽  
Devin P. Bendixsen ◽  
...  
Keyword(s):  
Telomere Length ◽  
Real Time ◽  
Quantitative Pcr ◽  
Model Organism ◽  
Dna Repeats ◽  
Vertebrate Species ◽  
Computational Tool ◽  
Telomeric Dna ◽  
Real Time Quantitative Pcr ◽  
Length Measurements

Telomere length dynamics are an established biomarker of health and aging in animals. The study of telomeres in numerous species has been facilitated by methods to measure telomere length by real-time quantitative PCR (qPCR). In this method, telomere length is determined by quantifying the amount of telomeric DNA repeats in a sample and normalizing this to the total amount of genomic DNA. This normalization requires the development of genomic reference primers suitable for qPCR, which remains challenging in non-model organism with genomes that have not been sequenced. Here we report reference primers that can be used in qPCR to measure telomere lengths in any vertebrate species. We designed primer pairs to amplify genetic elements that are highly conserved between evolutionarily distant taxa and tested them in species that span the vertebrate tree of life. We report five primer pairs that meet the specificity and reproducibility standards of qPCR. In addition, we demonstrate how to choose the best primers for a given species by testing the primers on multiple individuals within a species and applying an established computational tool. These reference primers can facilitate the application of qPCR-based telomere length measurements in any vertebrate species of ecological or economic interest.

scholarly journals Telomere-Associated Protein TIN2 Is Essential for Early Embryonic Development through a Telomerase-Independent Pathway

2004 ◽  
Vol 24 (15) ◽  
pp. 6631-6634 ◽  
Author(s):  
Y. Jeffrey Chiang ◽  
Sahn-Ho Kim ◽  
Lino Tessarollo ◽  
Judith Campisi ◽  
Richard J. Hodes
Keyword(s):  
Embryonic Development ◽  
Telomere Length ◽  
Embryonic Lethality ◽  
Negative Regulator ◽  
Telomeric Dna ◽  
Interacting Protein ◽  
Telomere Elongation ◽  
Dna Repeat ◽  
Early Embryonic Lethality ◽  
Length Regulation

ABSTRACT TIN2 is a negative regulator of telomere elongation that interacts with telomeric DNA repeat binding factor 1 (TRF1) and affects telomere length by a telomerase-dependent mechanism. Here we show that inactivation of the mouse TRF1-interacting protein 2 (TIN2) gene results in early embryonic lethality. We further observed that the embryonic lethality of TIN2 mutant mice was not affected by inactivation of the telomerase reverse transcriptase gene, indicating that embryonic lethality is not the result of telomerase-dependent changes in telomere length or function. Our findings suggest that TIN2 has a role independent of telomere length regulation that is essential for embryonic development and cell viability.

scholarly journals Control of Human Telomere Length by TRF1 and TRF2

2000 ◽  
Vol 20 (5) ◽  
pp. 1659-1668 ◽  
Author(s):  
Agata Smogorzewska ◽  
Bas van Steensel ◽  
Alessandro Bianchi ◽  
Stefan Oelmann ◽  
Matthias R. Schaefer ◽  
...  
Keyword(s):  
Telomere Length ◽  
Negative Regulator ◽  
Loop Model ◽  
Telomeric Dna ◽  
Telomere Elongation ◽  
Original Length ◽  
Population Doublings ◽  
Ttaggg Repeat

ABSTRACT Telomere length in human cells is controlled by a homeostasis mechanism that involves telomerase and the negative regulator of telomere length, TRF1 (TTAGGG repeat binding factor 1). Here we report that TRF2, a TRF1-related protein previously implicated in protection of chromosome ends, is a second negative regulator of telomere length. Overexpression of TRF2 results in the progressive shortening of telomere length, similar to the phenotype observed with TRF1. However, while induction of TRF1 could be maintained over more than 300 population doublings and resulted in stable, short telomeres, the expression of exogenous TRF2 was extinguished and the telomeres eventually regained their original length. Consistent with their role in measuring telomere length, indirect immunofluorescence indicated that both TRF1 and TRF2 bind to duplex telomeric DNA in vivo and are more abundant on telomeres with long TTAGGG repeat tracts. Neither TRF1 nor TRF2 affected the expression level of telomerase. Furthermore, the presence of TRF1 or TRF2 on a short linear telomerase substrate did not inhibit the enzymatic activity of telomerase in vitro. These findings are consistent with the recently proposed t loop model of telomere length homeostasis in which telomerase-dependent telomere elongation is blocked by sequestration of the 3′ telomere terminus in TRF1- and TRF2-induced telomeric loops.

scholarly journals A Waddington Epigenetic Landscape for the C. elegans embryo

2020 ◽  
Author(s):  
Ahmed Elewa
Keyword(s):  
Stress Response ◽  
Embryonic Development ◽  
Small Rnas ◽  
Expression Profiles ◽  
Epigenetic Landscape ◽  
C Elegans ◽  
Visual Model ◽  
Similar Expression ◽  
Redundant Genes ◽  
And Behavior

AbstractWaddington’s Epigenetic Landscape provides a visual model for both robust and adaptable development. Generating and exploring a Waddington epigenetic landscape for the early C. elegans embryo suggests that the key shapers of the landscape are genes that lie at the nexus between stress response and behavior and include genes that are regulated by transgenerational neuronal small RNAs. Curiously, several genes shape the early landscape of one lineage and then pattern, differentiate or are enriched in another lineage. Additionally, paralogs with similar expression profiles contribute differently to shaping the modeled landscape. This work suggests that robust embryonic development is initialized by differential deployment of redundant genes and by transgenerational cues that configure the epigenetic landscape to adapt to a changing world.

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