Nucleosome organization and chromatin dynamics in telomeres

Ichikawa, Yuichi; Nishimura, Yoshifumi; Kurumizaka, Hitoshi; Shimizu, Mitsuhiro

doi:10.1515/bmc-2014-0035

Cited by 11 publications

(17 citation statements)

References 71 publications

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“…In addition, overexpression of telomerase leads to telomeres elongation and higher levels of H3K9me3 at telomeric repeats ( 31 ). This and other results have led to the idea that long telomeres are more heterochromatic than short telomeres ( 16 ). However, late passage HS68 primary fibroblasts, which have short telomeres, have lower levels of H3K4 methylation at telomeric repeats than early passage fibroblast ( 28 ).…”

Section: Discussionmentioning

confidence: 83%

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Epigenetic features of human telomeres

Cubiles

Barroso

Vaquero-Sedas

et al. 2018

Nucleic Acids Research

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Although subtelomeric regions in humans are heterochromatic, the epigenetic nature of human telomeres remains controversial. This controversy might have been influenced by the confounding effect of subtelomeric regions and interstitial telomeric sequences (ITSs) on telomeric chromatin structure analyses. In addition, different human cell lines might carry diverse epigenetic marks at telomeres. We have developed a reliable procedure to study the chromatin structure of human telomeres independently of subtelomeres and ITSs. This procedure is based on the statistical analysis of multiple ChIP-seq experiments. We have found that human telomeres are not enriched in the heterochromatic H3K9me3 mark in most of the common laboratory cell lines, including embryonic stem cells. Instead, they are labeled with H4K20me1 and H3K27ac, which might be established by p300. These results together with previously published data argue that subtelomeric heterochromatin might control human telomere functions. Interestingly, U2OS cells that exhibit alternative lengthening of telomeres have heterochromatic levels of H3K9me3 in their telomeres.

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Section: Discussionmentioning

confidence: 83%

“…The epigenetic nature of human telomeres remains controversial ( 5 , 8 , 9 , 16 ). While some groups propose that telomeres are heterochromatic, other groups have reported that telomeres have low levels of heterochromatic marks and exhibit euchromatic modifications.…”

Section: Introductionmentioning

confidence: 99%

Epigenetic features of human telomeres

Cubiles

Barroso

Vaquero-Sedas

et al. 2018

Nucleic Acids Research

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“…The epigenetic nature of telomeres and subtelomeres remains controversial ( Vaquero-Sedas and Vega-Palas 2011 , Galati et al 2013 , Ichikawa et al 2015 , Adamusová et al 2019 ). In the classic model, animal and plant telomeres were interpreted as heterochromatic structures ( Kavi et al 2005 , Postepska-Igielska et al 2013 ).…”

Section: Epigenetic Regulation Of Telomere and Subtelomere Regionsmentioning

confidence: 99%

The epigenetic regulation of centromeres and telomeres in plants and animals

Achrem

Szućko

Kalinka

2020

CCG

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The centromere is a chromosomal region where the kinetochore is formed, which is the attachment point of spindle fibers. Thus, it is responsible for the correct chromosome segregation during cell division. Telomeres protect chromosome ends against enzymatic degradation and fusions, and localize chromosomes in the cell nucleus. For this reason, centromeres and telomeres are parts of each linear chromosome that are necessary for their proper functioning. More and more research results show that the identity and functions of these chromosomal regions are epigenetically determined. Telomeres and centromeres are both usually described as highly condensed heterochromatin regions. However, the epigenetic nature of centromeres and telomeres is unique, as epigenetic modifications characteristic of both eu- and heterochromatin have been found in these areas. This specificity allows for the proper functioning of both regions, thereby affecting chromosome homeostasis. This review focuses on demonstrating the role of epigenetic mechanisms in the functioning of centromeres and telomeres in plants and animals.

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“…On the one hand, in silico genomic analyses show that ITSs are not very abundant in the human genome, although they can be found in most human subtelomeric regions [16,24,26]. On the other hand, micrococcal nuclease (MNase) digestion experiments reveal that human telomeres have the short nucleosomal spacing characteristic of eukaryotic telomeres [31,32,33]. MNase preferentially cuts the linker internucleosomal DNA.…”

Section: Analysis Of the Epigenetic Features Of Human Telomeres Bymentioning

confidence: 99%

Assessing the Epigenetic Status of Human Telomeres

Vaquero-Sedas

Vega-Palas

2019

Cells

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The epigenetic modifications of human telomeres play a relevant role in telomere functions and cell proliferation. Therefore, their study is becoming an issue of major interest. These epigenetic modifications are usually analyzed by microscopy or by chromatin immunoprecipitation (ChIP). However, these analyses could be challenged by subtelomeres and/or interstitial telomeric sequences (ITSs). Whereas telomeres and subtelomeres cannot be differentiated by microscopy techniques, telomeres and ITSs might not be differentiated in ChIP analyses. In addition, ChIP analyses of telomeres should be properly controlled. Hence, studies focusing on the epigenetic features of human telomeres have to be carefully designed and interpreted. Here, we present a comprehensive discussion on how subtelomeres and ITSs might influence studies of human telomere epigenetics. We specially focus on the influence of ITSs and some experimental aspects of the ChIP technique on ChIP analyses. In addition, we propose a specific pipeline to accurately perform these studies. This pipeline is very simple and can be applied to a wide variety of cells, including cancer cells. Since the epigenetic status of telomeres could influence cancer cells proliferation, this pipeline might help design precise epigenetic treatments for specific cancer types.

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Nucleosome organization and chromatin dynamics in telomeres

Cited by 11 publications

References 71 publications

Epigenetic features of human telomeres

Epigenetic features of human telomeres

The epigenetic regulation of centromeres and telomeres in plants and animals

Assessing the Epigenetic Status of Human Telomeres

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