scholarly journals The methyl phosphate capping enzyme Bin3 is a stable component of the fission yeast telomerase holoenzyme

2021 ◽  
Author(s):  
Jennifer Porat ◽  
Moaine El Baidouri ◽  
Jorg Grigull ◽  
Jean-Marc Deragon ◽  
Mark A. Bayfield
Keyword(s):  
Fission Yeast ◽  
Genome Integrity ◽  
Methyltransferase Activity ◽  
Stable Component ◽  
U6 Snrna ◽  
Yeast Telomerase ◽  
Two Factors ◽  
Capping Enzyme ◽  
Methyl Phosphate ◽  
Insight Into

AbstractThe telomerase holoenzyme is critical for maintaining eukaryotic genome integrity. In addition to a reverse transcriptase and an RNA template, telomerase contains additional proteins that protect the telomerase RNA and promote holoenzyme assembly. Here we report that the methyl phosphate capping enzyme (MePCE) Bin3 is a stable component of the S. pombe telomerase holoenzyme. Bin3 associates with the telomerase and the U6 snRNA through an interaction with the recently described LARP7 family member Pof8, and we demonstrate that these two factors are evolutionarily linked in fungi. Our data suggest that the association of Bin3 with telomerase is independent of its methyltransferase activity, but rather that Bin3 negatively regulates TER1 levels and telomere length. Taken together, this work yields new insight into the composition, assembly, and regulation of the telomerase holoenzyme in fission yeast as well as the breadth of its evolutionary conservation.

scholarly journals Computational modelling of chromosome re-replication in mutant strains of fission yeast

2020 ◽  
Author(s):  
Béla Novák ◽  
John J Tyson
Keyword(s):  
Dna Replication ◽  
Fission Yeast ◽  
Computational Modelling ◽  
Mitotic Cell ◽  
Cyclin Dependent Kinase ◽  
Slow Increase ◽  
Cell Cycles ◽  
Mitotic Cyclin ◽  
The Mathematical Model ◽  
Insight Into

AbstractTypically cells replicate their genome only once per division cycle, but under some circumstances, both natural and unnatural, cells synthesize an overabundance of DNA, either in a disorganized fashion (‘over-replication’) or by a systematic doubling of chromosome number (‘endoreplication’). These variations on the theme of DNA replication and division have been studied in strains of fission yeast, Schizosaccharomyces pombe, carrying mutations that interfere with the function of mitotic cyclin-dependent kinase (Cdk1:Cdc13) without impeding the roles of DNA-replication licensing factor (Cdc18) and S-phase cyclin-dependent kinase (Cdk1:Cig2). Some of these mutations support endoreplication, and some over-replication. In this paper, we propose a dynamical model of the interactions among the proteins governing DNA replication and cell division in fission yeast. By computational simulations of the mathematical model, we account for the observed phenotypes of these re-replicating mutants, and by theoretical analysis of the dynamical system, we provide insight into the molecular distinctions between over-replicating and endoreplicating cells. In case of induced over-production of regulatory proteins, our model predicts that cells first switch from normal mitotic cell cycles to growth-controlled endoreplication, and ultimately to disorganized over-replication, parallel to the slow increase of protein to very high levels.

scholarly journals Controlled Construction of Stable Network Structure Composed of Honeycomb-Shaped Microhydrogels

Life ◽  
2018 ◽  
Vol 8 (4) ◽  
pp. 38 ◽  
Author(s):  
Masayuki Hayakawa ◽  
Satoshi Umeyama ◽  
Ken Nagai ◽  
Hiroaki Onoe ◽  
Masahiro Takinoue
Keyword(s):  
Cell Communication ◽  
Model Systems ◽  
Stable Component ◽  
Photosensitive Polymer ◽  
A Cell ◽  
External Stimuli ◽  
Structural Instabilities ◽  
Insight Into ◽  
Stable Network ◽  
Microfluidic Technique

Recently, the construction of models for multicellular systems such as tissues has been attracting great interest. These model systems are expected to reproduce a cell communication network and provide insight into complicated functions in living systems./Such network structures have mainly been modelled using a droplet and a vesicle. However, in the droplet and vesicle network, there are difficulties attributed to structural instabilities due to external stimuli and perturbations. Thus, the fabrication of a network composed of a stable component such as hydrogel is desired. In this article, the construction of a stable network composed of honeycomb-shaped microhydrogels is described. We produced the microhydrogel network using a centrifugal microfluidic technique and a photosensitive polymer. In the network, densely packed honeycomb-shaped microhydrogels were observed. Additionally, we successfully controlled the degree of packing of microhydrogels in the network by changing the centrifugal force. We believe that our stable network will contribute to the study of cell communication in multicellular systems.

scholarly journals Nucleosome–nucleosome interactions via histone tails and linker DNA regulate nuclear rigidity

2017 ◽  
Vol 28 (11) ◽  
pp. 1580-1589 ◽  
Author(s):  
Yuta Shimamoto ◽  
Sachiko Tamura ◽  
Hiroshi Masumoto ◽  
Kazuhiro Maeshima
Keyword(s):  
Molecular Mechanisms ◽  
Mechanical Response ◽  
Nuclear Architecture ◽  
Living Cells ◽  
Genome Integrity ◽  
Biological Processes ◽  
Cell Nuclei ◽  
Histone Tails ◽  
Insight Into

Cells, as well as the nuclei inside them, experience significant mechanical stress in diverse biological processes, including contraction, migration, and adhesion. The structural stability of nuclei must therefore be maintained in order to protect genome integrity. Despite extensive knowledge on nuclear architecture and components, however, the underlying physical and molecular mechanisms remain largely unknown. We address this by subjecting isolated human cell nuclei to microneedle-based quantitative micromanipulation with a series of biochemical perturbations of the chromatin. We find that the mechanical rigidity of nuclei depends on the continuity of the nucleosomal fiber and interactions between nucleosomes. Disrupting these chromatin features by varying cation concentration, acetylating histone tails, or digesting linker DNA results in loss of nuclear rigidity. In contrast, the levels of key chromatin assembly factors, including cohesin, condensin II, and CTCF, and a major nuclear envelope protein, lamin, are unaffected. Together with in situ evidence using living cells and a simple mechanical model, our findings reveal a chromatin-based regulation of the nuclear mechanical response and provide insight into the significance of local and global chromatin structures, such as those associated with interdigitated or melted nucleosomal fibers.

scholarly journals Rad3ATR Decorates Critical Chromosomal Domains with γH2A to Protect Genome Integrity during S-Phase in Fission Yeast

PLoS Genetics ◽  
2010 ◽  
Vol 6 (7) ◽  
pp. e1001032 ◽  
Author(s):  
Sophie Rozenzhak ◽  
Eva Mejía-Ramírez ◽  
Jessica S. Williams ◽  
Lana Schaffer ◽  
Jennifer A. Hammond ◽  
...  
Keyword(s):  
Fission Yeast ◽  
S Phase ◽  
Genome Integrity

scholarly journals Establishment of expression-state boundaries by Rif1 and Taz1 in fission yeast

2017 ◽  
Vol 114 (5) ◽  
pp. 1093-1098 ◽  
Author(s):  
Tea Toteva ◽  
Bethany Mason ◽  
Yutaka Kanoh ◽  
Peter Brøgger ◽  
Daniel Green ◽  
...  
Keyword(s):  
Dna Replication ◽  
Fission Yeast ◽  
Replication Timing ◽  
Genetic Screens ◽  
Origin Firing ◽  
Regulate Gene Expression ◽  
Boundary Formation ◽  
Amino Terminal ◽  
Amino Terminal Domain ◽  
Insight Into

The Shelterin component Rif1 has emerged as a global regulator of the replication-timing program in all eukaryotes examined to date, possibly by modulating the 3D-organization of the genome. In fission yeast a second Shelterin component, Taz1, might share similar functions. Here, we identified unexpected properties for Rif1 and Taz1 by conducting high-throughput genetic screens designed to identifycis-andtrans-acting factors capable of creating heterochromatin–euchromatin boundaries in fission yeast. The preponderance ofcis-acting elements identified in the screens originated from genomic loci bound by Taz1 and associated with origins of replication whose firing is repressed by Taz1 and Rif1. Boundary formation and gene silencing by these elements required Taz1 and Rif1 and coincided with altered replication timing in the region. Thus, small chromosomal elements sensitive to Taz1 and Rif1 (STAR) could simultaneously regulate gene expression and DNA replication over a large domain, at the edge of which they established a heterochromatin–euchromatin boundary. Taz1, Rif1, and Rif1-associated protein phosphatases Sds21 and Dis2 were each sufficient to establish a boundary when tethered to DNA. Moreover, efficient boundary formation required the amino-terminal domain of the Mcm4 replicative helicase onto which the antagonistic activities of the replication-promoting Dbf4-dependent kinase and Rif1-recruited phosphatases are believed to converge to control replication origin firing. Altogether these observations provide an insight into a coordinated control of DNA replication and organization of the genome into expression domains.

scholarly journals A Double Mutant between Fission Yeast Telomerase and RecQ Helicase Is Sensitive to Thiabendazole, an Anti-Microtubule Drug

2012 ◽  
Vol 76 (2) ◽  
pp. 264-269 ◽  
Author(s):  
Shinobu UKIMORI ◽  
Naoki KAWABATA ◽  
Hideki SHIMADA ◽  
Ryota IMANO ◽  
Katsunori TAKAHASHI ◽  
...  
Keyword(s):  
Fission Yeast ◽  
Double Mutant ◽  
Recq Helicase ◽  
Yeast Telomerase

Legal Typologies and Topologies: The Construction of Indigenous Alterity and Its Spatialization Within the Colombian Constitutional Court

2014 ◽  
Vol 39 (02) ◽  
pp. 334-360 ◽  
Author(s):  
Diana Bocarejo
Keyword(s):  
Indigenous Peoples ◽  
Minority Rights ◽  
Customary Law ◽  
Constitutional Court ◽  
Cultural Survival ◽  
Legal Discourses ◽  
Two Factors ◽  
The Relationship ◽  
Insight Into

This article examines the different legal articulations between indigenous typologies and topologies, that is, the relationship between someone classified as an indigenous subject, a grantee of minority rights, and the spatial arrangements such as reservations or ancestral territories considered necessary for indigenous “cultural survival.” I analyze how the jurisprudence of the Colombian Constitutional Court manifests and rests on the diverse combinations of these two factors. The typology/topology binary characterizes the manner in which these legal discourses portray indigeneity and culture. This binary also offers insight into a broad range of issues, including the access that indigenous peoples have to minority rights, the use of customary law, and the spatial delimitations that frame indigenous legal jurisdictions. Some of the complexities that arise from this binary are: the conceptualization of indigenous places as habitats, the idea of culture as a list of traits, and the concept of “degrees” of indigeneity that determine these peoples' access to minority rights.

A LONGITUDINAL STUDY OF EATING DISORDERS AMONG COLLEGE WOMEN

1999 ◽  
Vol 13 (3) ◽  
pp. 385-408 ◽  
Author(s):  
SHARLENE HESSE-BIBER ◽  
MARGARET MARINO ◽  
DIANE WATTS-ROY
Keyword(s):  
Body Image ◽  
Eating Disordered ◽  
Time Period ◽  
Two Factors ◽  
College Population ◽  
History Of ◽  
Food Body ◽  
The Relationship ◽  
Insight Into

This study provides insight into factors that determine whether women in the college population who exhibit eating-disordered behavior during their college years recover during their postcollege years. The study assessed changes in the eating patterns of 21 women across a six-year time period, from sophomore year in college to two years postcollege. Eleven of the women get better during their postcollege year, whereas 10 of the women continue to struggle with disordered eating. The major differences between the two groups revolve around the relationship between autonomy and relation. Women who get better negotiate the tension between autonomy and relatedness and are more likely to have higher selfesteem based on a more positive self-concept; this, in turn, leads to healthier relationships with food and body image. Two factors that appear to influence this negotiation include (I) one's history of chronic physical or sexual abuse and (2) the quality of familial messages about food, body image, relationship, and autonomy.

scholarly journals Differential requirement of MED14 and UVH6 for heterochromatin transcription upon destabilization of silencing

2018 ◽  
Author(s):  
Pierre Bourguet ◽  
Stève de Bossoreille ◽  
Leticia López-González ◽  
Marie-Noëlle Pouch-Pélissier ◽  
Ángeles Gómez-Zambrano ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Heat Stress ◽  
Environmental Changes ◽  
Constitutive Heterochromatin ◽  
Epigenetic Marks ◽  
Two Factors ◽  
Silencing Pathways ◽  
Heterochromatin Silencing ◽  
Insight Into ◽  
Chromatin Patterns

AbstractConstitutive heterochromatin is commonly associated with high levels of repressive epigenetic marks and is stably maintained transcriptionally silent by the concerted action of different, yet convergent, silencing pathways. Reactivation of heterochromatin transcription is generally associated with alterations in levels of these epigenetic marks. However, in mutants for particular epigenetic regulators, or upon particular environmental changes such as heat stress, heterochromatin-associated silencing is destabilized without noticeable changes in epigenetic marks. This suggests that transcription can occur in a non-permissive chromatin context, yet the factors involved remain poorly known. Here, we show that heat stress-induced transcription of heterochromatin depends on the TFIIH component UVH6 and the Mediator subunit MED14. Mutants for these two factors exhibit hypersensitivity to heat stress, and under these conditions, UVH6 and MED14 are required for transcription of a high number of loci. We further show that MED14, but not UVH6, is required for transcription when heterochromatin silencing is destabilized in the absence of stress. In this case, MED14 requires proper chromatin patterns of repressive epigenetic marks for its function. We also uncover that MED14 regulates non-CG DNA methylation at a subset of RNA-directed DNA methylation target loci. These findings provide insight into the control of heterochromatin transcription upon silencing destabilization and identify MED14 as a regulator of DNA methylation.

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