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ATR contributes to telomere maintenance in human cells.

Pennarun G, Hoffschir F, Revaud D, Granotier C, Gauthier LR, Mailliet P, Biard DS, Boussin FD - Nucleic Acids Res. (2010)

Bottom Line: The telomere aberrations resulting from ATR deficiency (i.e. sister telomere fusions and chromatid-type telomere aberrations) are mainly generated during and/or after telomere replication, and involve both leading and lagging strand telomeres as shown by chromosome orientation-FISH (CO-FISH).Moreover, we show that ATR deficiency strongly sensitizes cells to the G-quadruplex ligand 360A, enhancing sister telomere fusions and chromatid-type telomere aberrations involving specifically the lagging strand telomeres.Altogether, these data reveal that ATR plays a critical role in telomere maintenance during and/or after telomere replication in human cells.

View Article: PubMed Central - PubMed

Affiliation: CEA/DSV/iRCM/SCSR, Laboratoire de Radiopathologie, INSERM-Université Paris VII U967, 92265 Fontenay-aux-Roses, France.

ABSTRACT
Telomere maintenance is essential to preserve genomic stability and involves several telomere-specific proteins as well as DNA replication and repair proteins. The kinase ATR, which has a crucial function in maintaining genome integrity from yeast to human, has been shown to be involved in telomere maintenance in several eukaryotic organisms, including yeast, Arabidopsis and Drosophila. However, its role in telomere maintenance in mammals remains poorly explored. Here, we report by using telomere-fluorescence in situ hybridization (Telo-FISH) on metaphase chromosomes that ATR deficiency causes telomere instability both in primary human fibroblasts from Seckel syndrome patients and in HeLa cells. The telomere aberrations resulting from ATR deficiency (i.e. sister telomere fusions and chromatid-type telomere aberrations) are mainly generated during and/or after telomere replication, and involve both leading and lagging strand telomeres as shown by chromosome orientation-FISH (CO-FISH). Moreover, we show that ATR deficiency strongly sensitizes cells to the G-quadruplex ligand 360A, enhancing sister telomere fusions and chromatid-type telomere aberrations involving specifically the lagging strand telomeres. Altogether, these data reveal that ATR plays a critical role in telomere maintenance during and/or after telomere replication in human cells.

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Increase in sister telomere fusions and chromatid-type telomere aberrations in ATR-deficient Seckel fibroblasts. (A) Representative metaphase spread from ATR-deficient fibroblasts GM18366 (a) hybridized with a telomeric PNA probe (red) in Telo-FISH experiments. Examples of telomere aberrations found in metaphases from Seckel fibroblasts (b-e): sister telomere fusion (b); sister telomere loss (c); telomere doublet (d) and terminal deletion (e). (B) Histograms showing the mean percentages of chromosomes with the indicated telomere aberrations per cell from Seckel fibroblasts (GM18366 and GM09812) and NHF, one of the six normal fibroblasts used as controls, showing the highest levels of telomere aberrations—results obtained with the five others are given in Supplementary Figure S1. Mean percentages ± standard errors of the mean (SEM) were calculated from at least 47 metaphases for each cell lines (*t-test P-value ≤ 0.05; **P < 0.001; ***P < 0.0001). Box graph showing the distributions of the percentages of the telomere aberrations per cell is given in Supplementary Figure S2.
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Figure 1: Increase in sister telomere fusions and chromatid-type telomere aberrations in ATR-deficient Seckel fibroblasts. (A) Representative metaphase spread from ATR-deficient fibroblasts GM18366 (a) hybridized with a telomeric PNA probe (red) in Telo-FISH experiments. Examples of telomere aberrations found in metaphases from Seckel fibroblasts (b-e): sister telomere fusion (b); sister telomere loss (c); telomere doublet (d) and terminal deletion (e). (B) Histograms showing the mean percentages of chromosomes with the indicated telomere aberrations per cell from Seckel fibroblasts (GM18366 and GM09812) and NHF, one of the six normal fibroblasts used as controls, showing the highest levels of telomere aberrations—results obtained with the five others are given in Supplementary Figure S1. Mean percentages ± standard errors of the mean (SEM) were calculated from at least 47 metaphases for each cell lines (*t-test P-value ≤ 0.05; **P < 0.001; ***P < 0.0001). Box graph showing the distributions of the percentages of the telomere aberrations per cell is given in Supplementary Figure S2.

Mentions: Means of chromosomes with telomere aberration/cell ± SEM (%) were determined by Telo-FISH on at least 47 metaphases per sample. The different types of telomere aberrations observed are listed in Figure 1 and Supplementary Figure S1. The table also gives age of donors and number of passages at which Telo-FISH has been done.


ATR contributes to telomere maintenance in human cells.

Pennarun G, Hoffschir F, Revaud D, Granotier C, Gauthier LR, Mailliet P, Biard DS, Boussin FD - Nucleic Acids Res. (2010)

Increase in sister telomere fusions and chromatid-type telomere aberrations in ATR-deficient Seckel fibroblasts. (A) Representative metaphase spread from ATR-deficient fibroblasts GM18366 (a) hybridized with a telomeric PNA probe (red) in Telo-FISH experiments. Examples of telomere aberrations found in metaphases from Seckel fibroblasts (b-e): sister telomere fusion (b); sister telomere loss (c); telomere doublet (d) and terminal deletion (e). (B) Histograms showing the mean percentages of chromosomes with the indicated telomere aberrations per cell from Seckel fibroblasts (GM18366 and GM09812) and NHF, one of the six normal fibroblasts used as controls, showing the highest levels of telomere aberrations—results obtained with the five others are given in Supplementary Figure S1. Mean percentages ± standard errors of the mean (SEM) were calculated from at least 47 metaphases for each cell lines (*t-test P-value ≤ 0.05; **P < 0.001; ***P < 0.0001). Box graph showing the distributions of the percentages of the telomere aberrations per cell is given in Supplementary Figure S2.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2874998&req=5

Figure 1: Increase in sister telomere fusions and chromatid-type telomere aberrations in ATR-deficient Seckel fibroblasts. (A) Representative metaphase spread from ATR-deficient fibroblasts GM18366 (a) hybridized with a telomeric PNA probe (red) in Telo-FISH experiments. Examples of telomere aberrations found in metaphases from Seckel fibroblasts (b-e): sister telomere fusion (b); sister telomere loss (c); telomere doublet (d) and terminal deletion (e). (B) Histograms showing the mean percentages of chromosomes with the indicated telomere aberrations per cell from Seckel fibroblasts (GM18366 and GM09812) and NHF, one of the six normal fibroblasts used as controls, showing the highest levels of telomere aberrations—results obtained with the five others are given in Supplementary Figure S1. Mean percentages ± standard errors of the mean (SEM) were calculated from at least 47 metaphases for each cell lines (*t-test P-value ≤ 0.05; **P < 0.001; ***P < 0.0001). Box graph showing the distributions of the percentages of the telomere aberrations per cell is given in Supplementary Figure S2.
Mentions: Means of chromosomes with telomere aberration/cell ± SEM (%) were determined by Telo-FISH on at least 47 metaphases per sample. The different types of telomere aberrations observed are listed in Figure 1 and Supplementary Figure S1. The table also gives age of donors and number of passages at which Telo-FISH has been done.

Bottom Line: The telomere aberrations resulting from ATR deficiency (i.e. sister telomere fusions and chromatid-type telomere aberrations) are mainly generated during and/or after telomere replication, and involve both leading and lagging strand telomeres as shown by chromosome orientation-FISH (CO-FISH).Moreover, we show that ATR deficiency strongly sensitizes cells to the G-quadruplex ligand 360A, enhancing sister telomere fusions and chromatid-type telomere aberrations involving specifically the lagging strand telomeres.Altogether, these data reveal that ATR plays a critical role in telomere maintenance during and/or after telomere replication in human cells.

View Article: PubMed Central - PubMed

Affiliation: CEA/DSV/iRCM/SCSR, Laboratoire de Radiopathologie, INSERM-Université Paris VII U967, 92265 Fontenay-aux-Roses, France.

ABSTRACT
Telomere maintenance is essential to preserve genomic stability and involves several telomere-specific proteins as well as DNA replication and repair proteins. The kinase ATR, which has a crucial function in maintaining genome integrity from yeast to human, has been shown to be involved in telomere maintenance in several eukaryotic organisms, including yeast, Arabidopsis and Drosophila. However, its role in telomere maintenance in mammals remains poorly explored. Here, we report by using telomere-fluorescence in situ hybridization (Telo-FISH) on metaphase chromosomes that ATR deficiency causes telomere instability both in primary human fibroblasts from Seckel syndrome patients and in HeLa cells. The telomere aberrations resulting from ATR deficiency (i.e. sister telomere fusions and chromatid-type telomere aberrations) are mainly generated during and/or after telomere replication, and involve both leading and lagging strand telomeres as shown by chromosome orientation-FISH (CO-FISH). Moreover, we show that ATR deficiency strongly sensitizes cells to the G-quadruplex ligand 360A, enhancing sister telomere fusions and chromatid-type telomere aberrations involving specifically the lagging strand telomeres. Altogether, these data reveal that ATR plays a critical role in telomere maintenance during and/or after telomere replication in human cells.

Show MeSH
Related in: MedlinePlus