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The three-dimensional organization of telomeres in the nucleus of mammalian cells.

Chuang TC, Moshir S, Garini Y, Chuang AY, Young IT, Vermolen B, van den Doel R, Mougey V, Perrin M, Braun M, Kerr PD, Fest T, Boukamp P, Mai S - BMC Biol. (2004)

Bottom Line: In tumor cells, the 3D telomere organization is distorted and aggregates are formed.The results emphasize a non-random and dynamic 3D nuclear telomeric organization and its importance to genomic stability.Based on our findings, it appears possible to examine telomeric aggregates suggestive of genomic instability in individual interphase nuclei and tissues without the need to examine metaphases.

View Article: PubMed Central - HTML - PubMed

Affiliation: Manitoba Institute of Cell Biology, CancerCare Manitoba, University of Manitoba, 675 McDermot Avenue, Winnipeg, MB, R3E 0V9, Canada. tcychuang@hotmail.com

ABSTRACT

Background: The observation of multiple genetic markers in situ by optical microscopy and their relevance to the study of three-dimensional (3D) chromosomal organization in the nucleus have been greatly developed in the last decade. These methods are important in cancer research because cancer is characterized by multiple alterations that affect the modulation of gene expression and the stability of the genome. It is, therefore, essential to analyze the 3D genome organization of the interphase nucleus in both normal and cancer cells.

Results: We describe a novel approach to study the distribution of all telomeres inside the nucleus of mammalian cells throughout the cell cycle. It is based on 3D telomere fluorescence in situ hybridization followed by quantitative analysis that determines the telomeres' distribution in the nucleus throughout the cell cycle. This method enables us to determine, for the first time, that telomere organization is cell-cycle dependent, with assembly of telomeres into a telomeric disk in the G2 phase. In tumor cells, the 3D telomere organization is distorted and aggregates are formed.

Conclusions: The results emphasize a non-random and dynamic 3D nuclear telomeric organization and its importance to genomic stability. Based on our findings, it appears possible to examine telomeric aggregates suggestive of genomic instability in individual interphase nuclei and tissues without the need to examine metaphases. Such new avenues of monitoring genomic instability could potentially impact on cancer biology, genetics, diagnostic innovations and surveillance of treatment response in medicine.

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The distribution of the telomeres in the nucleus volume is found by fitting a convex set of polygons that contains all the telomeres. This volume usually looks like either a sphere or a disk and can be described as an ellipsoid.
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Figure 1: The distribution of the telomeres in the nucleus volume is found by fitting a convex set of polygons that contains all the telomeres. This volume usually looks like either a sphere or a disk and can be described as an ellipsoid.

Mentions: To study the organization and structure of the genome in the nucleus, we took the approach of labelling only the telomeres and measuring their 3D organization as indicators for chromosomal distribution. After the 3D fluorescent measurements, the data were analyzed with a programme that was developed for this study. The programme finds all the telomeres in the nucleus; their size, intensity and shape; and determines the telomeric organization inside the volume of the nucleus. One crucial property that we analyzed was the distribution of the telomeres inside the nuclear volume. We first segmented the nucleus and found the centre of each telomere. We then found the smallest convex set of polygons that contains all the telomeres (Fig. 1). This was done by using the Quickhull algorithm [27]. In most cases, we found that the volume contained by the telomeres resembles either a sphere or a flattened sphere (disk). It can be described as an ellipsoid with two similar radii (a≈b) and a different third one (c; Fig. 2). Such a shape is called a spheroid. The level of flatness of the volume occupied by the telomeres can, therefore, be described by the ratio of the two radii that are different, a (or b) and c – a/c. The larger the ratio, the more oblate (or disk-like) is the shape of the volume occupied by the telomeres, while a/c≈1 means that the volume is spherical.


The three-dimensional organization of telomeres in the nucleus of mammalian cells.

Chuang TC, Moshir S, Garini Y, Chuang AY, Young IT, Vermolen B, van den Doel R, Mougey V, Perrin M, Braun M, Kerr PD, Fest T, Boukamp P, Mai S - BMC Biol. (2004)

The distribution of the telomeres in the nucleus volume is found by fitting a convex set of polygons that contains all the telomeres. This volume usually looks like either a sphere or a disk and can be described as an ellipsoid.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC425602&req=5

Figure 1: The distribution of the telomeres in the nucleus volume is found by fitting a convex set of polygons that contains all the telomeres. This volume usually looks like either a sphere or a disk and can be described as an ellipsoid.
Mentions: To study the organization and structure of the genome in the nucleus, we took the approach of labelling only the telomeres and measuring their 3D organization as indicators for chromosomal distribution. After the 3D fluorescent measurements, the data were analyzed with a programme that was developed for this study. The programme finds all the telomeres in the nucleus; their size, intensity and shape; and determines the telomeric organization inside the volume of the nucleus. One crucial property that we analyzed was the distribution of the telomeres inside the nuclear volume. We first segmented the nucleus and found the centre of each telomere. We then found the smallest convex set of polygons that contains all the telomeres (Fig. 1). This was done by using the Quickhull algorithm [27]. In most cases, we found that the volume contained by the telomeres resembles either a sphere or a flattened sphere (disk). It can be described as an ellipsoid with two similar radii (a≈b) and a different third one (c; Fig. 2). Such a shape is called a spheroid. The level of flatness of the volume occupied by the telomeres can, therefore, be described by the ratio of the two radii that are different, a (or b) and c – a/c. The larger the ratio, the more oblate (or disk-like) is the shape of the volume occupied by the telomeres, while a/c≈1 means that the volume is spherical.

Bottom Line: In tumor cells, the 3D telomere organization is distorted and aggregates are formed.The results emphasize a non-random and dynamic 3D nuclear telomeric organization and its importance to genomic stability.Based on our findings, it appears possible to examine telomeric aggregates suggestive of genomic instability in individual interphase nuclei and tissues without the need to examine metaphases.

View Article: PubMed Central - HTML - PubMed

Affiliation: Manitoba Institute of Cell Biology, CancerCare Manitoba, University of Manitoba, 675 McDermot Avenue, Winnipeg, MB, R3E 0V9, Canada. tcychuang@hotmail.com

ABSTRACT

Background: The observation of multiple genetic markers in situ by optical microscopy and their relevance to the study of three-dimensional (3D) chromosomal organization in the nucleus have been greatly developed in the last decade. These methods are important in cancer research because cancer is characterized by multiple alterations that affect the modulation of gene expression and the stability of the genome. It is, therefore, essential to analyze the 3D genome organization of the interphase nucleus in both normal and cancer cells.

Results: We describe a novel approach to study the distribution of all telomeres inside the nucleus of mammalian cells throughout the cell cycle. It is based on 3D telomere fluorescence in situ hybridization followed by quantitative analysis that determines the telomeres' distribution in the nucleus throughout the cell cycle. This method enables us to determine, for the first time, that telomere organization is cell-cycle dependent, with assembly of telomeres into a telomeric disk in the G2 phase. In tumor cells, the 3D telomere organization is distorted and aggregates are formed.

Conclusions: The results emphasize a non-random and dynamic 3D nuclear telomeric organization and its importance to genomic stability. Based on our findings, it appears possible to examine telomeric aggregates suggestive of genomic instability in individual interphase nuclei and tissues without the need to examine metaphases. Such new avenues of monitoring genomic instability could potentially impact on cancer biology, genetics, diagnostic innovations and surveillance of treatment response in medicine.

Show MeSH
Related in: MedlinePlus