scholarly journals Counting of Rif1p and Rif2p on Saccharomyces cerevisiae Telomeres Regulates Telomere Length

2004 ◽  
Vol 24 (24) ◽  
pp. 10857-10867 ◽  
Author(s):  
Daniel L. Levy ◽  
Elizabeth H. Blackburn
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Telomere Length ◽  
Pdz Domain ◽  
Protein Oligomerization ◽  
Telomeric Dna ◽  
C Terminus ◽  
Repeat Dna ◽  
Telomere Structure ◽  
Regulate Telomere Length ◽  
Oligomerization Domain

ABSTRACT Telomere length is negatively regulated by proteins of the telomeric DNA-protein complex. Rap1p in Saccharomyces cerevisiae binds the telomeric TG1-3 repeat DNA, and the Rap1p C terminus interacts with Rif1p and Rif2p. We investigated how these three proteins negatively regulate telomere length. We show that direct tethering of each Rif protein to a telomere shortens that telomere proportionally to the number of tethered molecules, similar to previously reported counting of Rap1p. Surprisingly, Rif proteins could also regulate telomere length even when the Rap1p C terminus was absent, and tethered Rap1p counting was completely dependent on the Rif proteins. Thus, Rap1p counting is in fact Rif protein counting. In genetic settings that cause telomeres to be abnormally long, tethering even a single Rif2p molecule was sufficient for maximal effectiveness in preventing the telomere overelongation. We show that a heterologous protein oligomerization domain, the mammalian PDZ domain, when fused to Rap1p can confer telomere length control. We propose that a nucleation and spreading mechanism is involved in forming the higher-order telomere structure that regulates telomere length.

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 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 The Ku subunit of telomerase binds Sir4 to recruit telomerase to lengthen telomeres in S. cerevisiae

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Evan P Hass ◽  
David C Zappulla
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Telomere Length ◽  
Chromatin Immunoprecipitation ◽  
Telomerase Rna ◽  
Silent Chromatin ◽  
Wild Type ◽  
Yeast Telomerase ◽  
Length Analysis ◽  
Telomere Lengthening ◽  
Regulate Telomere Length

In Saccharomyces cerevisiae and in humans, the telomerase RNA subunit is bound by Ku, a ring-shaped protein heterodimer best known for its function in DNA repair. Ku binding to yeast telomerase RNA promotes telomere lengthening and telomerase recruitment to telomeres, but how this is achieved remains unknown. Using telomere-length analysis and chromatin immunoprecipitation, we show that Sir4 – a previously identified Ku-binding protein that is a component of telomeric silent chromatin – is required for Ku-mediated telomere lengthening and telomerase recruitment. We also find that specifically tethering Sir4 directly to Ku-binding-defective telomerase RNA restores otherwise-shortened telomeres to wild-type length. These findings suggest that Sir4 is the telomere-bound target of Ku-mediated telomerase recruitment and provide one mechanism for how the Sir4-competing Rif1 and Rif2 proteins negatively regulate telomere length in yeast.

scholarly journals Distinct Requirements for Pot1 in Limiting Telomere Length and Maintaining Chromosome Stability

2005 ◽  
Vol 25 (13) ◽  
pp. 5567-5578 ◽  
Author(s):  
Jeremy T. Bunch ◽  
Nancy S. Bae ◽  
Jessica Leonardi ◽  
Peter Baumann
Keyword(s):  
Telomere Length ◽  
Dominant Negative ◽  
Dominant Negative Effect ◽  
Chromosome Stability ◽  
Telomeric Dna ◽  
Protective Function ◽  
C Terminus ◽  
Catastrophic Loss ◽  
Negative Effect ◽  
Linear Chromosomes

ABSTRACT The fission yeast Pot1 (protection of telomeres) protein binds to the single-stranded extensions at the ends of telomeres, where its presence is critical for the maintenance of linear chromosomes. Homologs of Pot1 have been identified in a wide variety of eukaryotes, including plants, animals, and humans. We now show that Pot1 plays dual roles in telomere length regulation and chromosome end protection. Using a series of Pot1 truncation mutants, we have defined distinct areas of the protein required for chromosome stability and for limiting access to telomere ends by telomerase. We provide evidence that a large portion of Pot1, including the N-terminal DNA binding domain and amino acids close to the C terminus, is essential for its protective function. C-terminal Pot1 fragments were found to exert a dominant-negative effect by displacing endogenous Pot1 from telomeres. Reducing telomere-bound Pot1 in this manner resulted in dramatic lengthening of the telomere tract. Upon further reduction of Pot1 at telomeres, the opposite phenotype was observed: loss of telomeric DNA and chromosome end fusions. Our results demonstrate that cells must carefully regulate the amount of telomere-bound Pot1 to differentiate between allowing access to telomerase and catastrophic loss of telomeres.

scholarly journals Rap1 Affects the Length and Heterogeneity of Human Telomeres

2003 ◽  
Vol 14 (12) ◽  
pp. 5060-5068 ◽  
Author(s):  
Bibo Li ◽  
Titia de Lange
Keyword(s):  
Telomere Length ◽  
Length Distribution ◽  
Negative Regulator ◽  
Deletion Mapping ◽  
Telomeric Dna ◽  
Cis Acting ◽  
Functional Changes ◽  
Functional Conservation ◽  
C Terminus ◽  
Interaction Domains

Telomere length is controlled in part by cis-acting negative regulators that limit telomere extension by telomerase. In budding yeast, the major telomere length regulator scRap1 binds to telomeric DNA and acts to inhibit telomere elongation in cis. Because the human Rap1 ortholog hRap1 does not bind to telomeric DNA directly but is recruited to telomeres by TRF2, we examined its role in telomere length control. The data are consistent with hRap1 being a negative regulator of telomere length, indicating functional conservation. Deletion mapping confirmed that hRap1 is tethered to telomeres through interaction of its C terminus with TRF2. The telomere length phenotypes of hRap1 deletion mutants implicated both the BRCT and Myb domain as protein interaction domains involved in telomere length regulation. By contrast, scRap1 binds to telomeres with its Myb domains and uses its C terminus to recruit the telomere length regulators Rif1 and Rif2. Together, our data show that although the role of Rap1 at telomeres has been largely conserved, the domains of Rap1 have undergone extensive functional changes during eukaryotic evolution. Surprisingly, hRap1 alleles lacking the BRCT domain diminished the heterogeneity of human telomeres, indicating that hRap1 also plays a role in the regulation of telomere length distribution.

scholarly journals Telomere length varies substantially between blood cell types in a reptile

2020 ◽  
Vol 7 (6) ◽  
pp. 192136 ◽  
Author(s):  
Mats Olsson ◽  
Nicholas J. Geraghty ◽  
Erik Wapstra ◽  
Mark Wilson
Keyword(s):  
Blood Cell ◽  
Telomere Length ◽  
Whole Blood ◽  
Phylogenetic Analyses ◽  
Natural Populations ◽  
Cell Types ◽  
Tissue Type ◽  
Telomeric Dna ◽  
Blood Cell Type ◽  
Widespread Phenomenon

Telomeres are repeat sequences of non-coding DNA-protein molecules that cap or intersperse metazoan chromosomes. Interest in telomeres has increased exponentially in recent years, to now include their ongoing dynamics and evolution within natural populations where individuals vary in telomere attributes. Phylogenetic analyses show profound differences in telomere length across non-model taxa. However, telomeres may also differ in length within individuals and between tissues. The latter becomes a potential source of error when researchers use different tissues for extracting DNA for telomere analysis and scientific inference. A commonly used tissue type for assessing telomere length is blood, a tissue that itself varies in terms of nuclear content among taxa, in particular to what degree their thrombocytes and red blood cells (RBCs) contain nuclei or not. Specifically, when RBCs lack nuclei, leucocytes become the main source of telomeric DNA. RBCs and leucocytes differ in lifespan and how long they have been exposed to ‘senescence' and erosion effects. We report on a study in which cells in whole blood from individual Australian painted dragon lizards ( Ctenophorus pictus ) were identified using flow cytometry and their telomere length simultaneously measured. Lymphocyte telomeres were on average 270% longer than RBC telomeres, and in azurophils (a reptilian monocyte), telomeres were more than 388% longer than those in RBCs. If this variation in telomere length among different blood cell types is a widespread phenomenon, and DNA for comparative telomere analyses are sourced from whole blood, evolutionary inference of telomere traits among taxa may be seriously complicated by the blood cell type comprising the main source of DNA.

scholarly journals Telomere Length and Oxidative Stress and Its Relation with Metabolic Syndrome Components in the Aging

Biology ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 253
Author(s):  
Graciela Gavia-García ◽  
Juana Rosado-Pérez ◽  
Taide Laurita Arista-Ugalde ◽  
Itzen Aguiñiga-Sánchez ◽  
Edelmiro Santiago-Osorio ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Metabolic Syndrome ◽  
Telomere Length ◽  
Scientific Evidence ◽  
Telomeric Dna ◽  
Biochemical Alterations ◽  
The Metabolic Syndrome ◽  
Age Related ◽  
And Function

A great amount of scientific evidence supports that Oxidative Stress (OxS) can contribute to telomeric attrition and also plays an important role in the development of certain age-related diseases, among them the metabolic syndrome (MetS), which is characterised by clinical and biochemical alterations such as obesity, dyslipidaemia, arterial hypertension, hyperglycaemia, and insulin resistance, all of which are considered as risk factors for type 2 diabetes mellitus (T2DM) and cardiovascular diseases, which are associated in turn with an increase of OxS. In this sense, we review scientific evidence that supports the association between OxS with telomere length (TL) dynamics and the relationship with MetS components in aging. It was analysed whether each MetS component affects the telomere length separately or if they all affect it together. Likewise, this review provides a summary of the structure and function of telomeres and telomerase, the mechanisms of telomeric DNA repair, how telomere length may influence the fate of cells or be linked to inflammation and the development of age-related diseases, and finally, how the lifestyles can affect telomere length.

scholarly journals Cdc13 N-Terminal Dimerization, DNA Binding, and Telomere Length Regulation

2010 ◽  
Vol 30 (22) ◽  
pp. 5325-5334 ◽  
Author(s):  
Meghan T. Mitchell ◽  
Jasmine S. Smith ◽  
Mark Mason ◽  
Sandy Harper ◽  
David W. Speicher ◽  
...  
Keyword(s):  
Dna Binding ◽  
Telomere Length ◽  
Functional Characterization ◽  
Point Mutations ◽  
Telomeric Dna ◽  
Dna Binding Domains ◽  
Binding Domains ◽  
Length Regulation ◽  
Telomere Length Regulation

ABSTRACT The essential yeast protein Cdc13 facilitates chromosome end replication by recruiting telomerase to telomeres, and together with its interacting partners Stn1 and Ten1, it protects chromosome ends from nucleolytic attack, thus contributing to genome integrity. Although Cdc13 has been studied extensively, the precise role of its N-terminal domain (Cdc13N) in telomere length regulation remains unclear. Here we present a structural, biochemical, and functional characterization of Cdc13N. The structure reveals that this domain comprises an oligonucleotide/oligosaccharide binding (OB) fold and is involved in Cdc13 dimerization. Biochemical data show that Cdc13N weakly binds long, single-stranded, telomeric DNA in a fashion that is directly dependent on domain oligomerization. When introduced into full-length Cdc13 in vivo, point mutations that prevented Cdc13N dimerization or DNA binding caused telomere shortening or lengthening, respectively. The multiple DNA binding domains and dimeric nature of Cdc13 offer unique insights into how it coordinates the recruitment and regulation of telomerase access to the telomeres.

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