Live Imaging of Telomeres

Hediger, Florence; Neumann, Frank; Houwe, Griet Van; Dubrana, Karine; Gasser, Susan M.

doi:10.1016/s0960-9822(02)01338-6

Cited by 279 publications

(167 citation statements)

References 49 publications

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“…This absence would very likely have implications for the local chromatin structure, and indeed we have shown that the histones of inactive and active var genes are differentially acetylated (12). Experiments in yeast (29,30), Drosophila (31), and mammalian systems (32) demonstrate that genes can be recruited from one area of the nucleus to another to be repressed. These recruitments are sometimes The same var gene is in a silenced state.…”

Section: Discussionmentioning

confidence: 88%

Antigenic variation inPlasmodium falciparumis associated with movement ofvarloci between subnuclear locations

Ralph

Scheidig-Benatar

Scherf

2005

Proc. Natl. Acad. Sci. U.S.A.

185

181

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Much of the success of Plasmodium falciparum in establishing persistent infections is attributed to immune evasion through antigenic variation. This process involves periodically exchanging variants of the major surface antigen PfEMP1, a protein also responsible for parasite cytoadherence. PfEMP1 is encoded by genes of the 60-member var family, located at subtelomeric and internal chromosome loci. The active or silenced state of var genes is heritable, and its control by nonsequence information remains puzzling. Using FISH analysis, we demonstrate that both internal and subtelomeric var genes are positioned at the nuclear periphery in their repressed state. Upon activation, the same var genes are still found in the periphery, indicating that this zone can be transcriptionally competent, rather than uniformly silenced. However, activation of a var gene is linked with altered positioning at the nuclear periphery, with subtelomeric var loci exiting chromosome end clusters and being relocated to distinct nuclear sites. Serial sectioning of parasite nuclei reveals areas of both condensed and noncondensed chromatin at the nuclear periphery. Our results demonstrate that regulation of antigenic variation is associated with subnuclear position effects and point to the existence of transcriptionally permissive perinuclear zones for var genes. malaria ͉ epigenetic ͉ telomere ͉ nucleus

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Section: Discussionmentioning

confidence: 88%

Antigenic variation inPlasmodium falciparumis associated with movement ofvarloci between subnuclear locations

Ralph

Scheidig-Benatar

Scherf

2005

Proc. Natl. Acad. Sci. U.S.A.

185

181

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“…There is precedent for chromatin proteins involved in transcription repression and present in limiting con- centrations being relocalized to sites of DNA damage in the cell, resulting in derepression of normally silent transcription units. For example, the Ku and SIR silencing proteins are normally sequestered at telomeres in Saccharomyces cerevisiae (54,73,74). However, after the introduction of DNA damage, these proteins are relocalized from the telomeres to DNA repair sites (75,76), resulting in derepression of genes normally silenced by telomere position effect (77).…”

Section: Up-regulation Of Silent Ess Correlates With a Block In Smentioning

confidence: 99%

Bloodstream Form-specific Up-regulation of Silent VSG Expression Sites and Procyclin in Trypanosoma brucei after Inhibition of DNA Synthesis or DNA Damage

Sheader

Vruchte

Rudenko

2004

Journal of Biological Chemistry

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The African trypanosome Trypanosoma brucei transcribes the active variant surface glycoprotein (VSG) gene from one of about 20 VSG expression sites (ESs). In order to study ES control, we made reporter lines with a green fluorescent protein gene inserted behind the promoter of different ESs. We attempted to disrupt the silencing machinery, and we used fluorescence-activated cell sorter analysis for the rapid and sensitive detection of ES up-regulation. We find that a range of treatments that either block nuclear DNA synthesis, like aphidicolin, or modify DNA-like cisplatin and 1-methyl-3-nitro-1-nitrosoguanidine results in up-regulation of silent ESs. Aphidicolin treatment was the most effective, with almost 80% of the cells expressing green fluorescent protein from a silent ES. All of these treatments blocked the cells in S phase. In contrast, a range of toxic chemicals had little or no effect on expression. These included berenil and pentamidine, which selectively cleave the mitochondrial kinetoplast DNA, the metabolic inhibitors suramin and difluoromethylornithine, and the mitotic inhibitor rhizoxin. Up-regulation also affected other RNA polymerase I (pol I) transcription units, as procyclin genes were also up-regulated after cells were treated with either aphidicolin or DNA-modifying agents. Strikingly, this up-regulation of silent pol I transcription units was bloodstream form-specific and was not observed in insect form T. brucei. We postulate that the redistribution of a limiting bloodstream form-specific factor involved in both silencing and DNA repair results in the derepression of normally silenced pol I transcription units after DNA damage.

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“…Centromeres of each chromosome cluster near the spindle pole body (SPB), 2,3) and telomeres bind to the nuclear envelope. [4][5][6][7] These localizations switch between the G 1 and S phases. Centromeres and telomeres move to the replication factory in the central region of the nucleus in the S phase.…”

mentioning

confidence: 94%

The Relationship between Chromosomal Positioning within the Nucleus and theSSD1Gene inSaccharomyces cerevisiae

Yanamoto

Miyamoto

Ikeda

et al. 2011

Bioscience, Biotechnology, and Biochemistry

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Live Imaging of Telomeres

Abstract: Interphase positioning of telomeres can be achieved through two partially redundant mechanisms. One requires the heterodimeric yKu complex, but not Mlp1 and Mlp2. The second requires Silent information regulators, correlates with transcriptional repression, and is specific to S phase.

Cited by 279 publications

References 49 publications

Antigenic variation inPlasmodium falciparumis associated with movement ofvarloci between subnuclear locations

Antigenic variation inPlasmodium falciparumis associated with movement ofvarloci between subnuclear locations

Bloodstream Form-specific Up-regulation of Silent VSG Expression Sites and Procyclin in Trypanosoma brucei after Inhibition of DNA Synthesis or DNA Damage

The Relationship between Chromosomal Positioning within the Nucleus and theSSD1Gene inSaccharomyces cerevisiae

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