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3D-FISH analysis reveals chromatid cohesion defect during interphase in Roberts syndrome.

Dupont C, Bucourt M, Guimiot F, Kraoua L, Smiljkovski D, Le Tessier D, Lebugle C, Gerard B, Spaggiari E, Bourdoncle P, Tabet AC, Benzacken B, Dupont JM - Mol Cytogenet (2014)

Bottom Line: Mutations in the ESCO2 (establishment of cohesion 1 homolog 2) gene located in 8p21.1 have been found in several families.ESCO2, a member of the cohesion establishing complex, has a role in the effective cohesion between sister chromatids.These changes may modify interactions between the chromatin and the proteins associated with the inner nuclear membrane or the pore complexes.

View Article: PubMed Central - PubMed

Affiliation: Unité fonctionnelle de Cytogénétique-Département de Génétique- APHP, Hôpital Robert Debré, 48 Bd Sérurier, 75935 Paris, France.

ABSTRACT

Background: Roberts syndrome (RBS) is a rare autosomal recessive disorder mainly characterized by growth retardation, limb defects and craniofacial anomalies. Characteristic cytogenetic findings are "railroad track" appearance of chromatids and premature centromere separation in metaphase spreads. Mutations in the ESCO2 (establishment of cohesion 1 homolog 2) gene located in 8p21.1 have been found in several families. ESCO2, a member of the cohesion establishing complex, has a role in the effective cohesion between sister chromatids. In order to analyze sister chromatids topography during interphase, we performed 3D-FISH using pericentromeric heterochromatin probes of chromosomes 1, 4, 9 and 16, on preserved nuclei from a fetus with RBS carrying compound heterozygous mutations in the ESCO2 gene.

Results: Along with the first observation of an abnormal separation between sister chromatids in heterochromatic regions, we observed a statistically significant change in the intranuclear localization of pericentromeric heterochromatin of chromosome 1 in cells of the fetus compared to normal cells, demonstrating for the first time a modification in the spatial arrangement of chromosome domains during interphase.

Conclusion: We hypothesize that the disorganization of nuclear architecture may result in multiple gene deregulations, either through disruption of DNA cis interaction -such as modification of chromatin loop formation and gene insulation - mediated by cohesin complex, or by relocation of chromosome territories. These changes may modify interactions between the chromatin and the proteins associated with the inner nuclear membrane or the pore complexes. This model offers a link between the molecular defect in cohesion and the complex phenotypic anomalies observed in RBS.

No MeSH data available.


Related in: MedlinePlus

Statistical representation of CB2 radial and mutual positions. (A): Distribution of each PH1 (=CB2 probe) radial position of normal cells (black rings) and Roberts cells (blue triangles). The median was calculated both for normal cells (Mrn, black line) and Roberts cells (MrR, blue line). Radial distances are expressed as a proportion of the radius. Mrn = 0.5285 and MrR = 0.6700: Wilcoxon test was significant (alpha = 0.05) with a p value of 0.0018 showing a significant relocation of PH1 territory towards the edge of the nucleus in Roberts cells. (B): Distribution of CB2 mutual position of normal and Roberts cells. The median was calculated both for normal cells (Mmn,black line) and Roberts cells (MmR, blue line). Mutual distances are expressed as a proportion of the diameter. Mmn = 0.4527 and MmR = 0.3813: Wilcoxon test was significant (alpha = 0.05) with a p value of 0.0829 showing a significant rapprochement of homologous PH1 territories in Roberts cells.
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Fig3: Statistical representation of CB2 radial and mutual positions. (A): Distribution of each PH1 (=CB2 probe) radial position of normal cells (black rings) and Roberts cells (blue triangles). The median was calculated both for normal cells (Mrn, black line) and Roberts cells (MrR, blue line). Radial distances are expressed as a proportion of the radius. Mrn = 0.5285 and MrR = 0.6700: Wilcoxon test was significant (alpha = 0.05) with a p value of 0.0018 showing a significant relocation of PH1 territory towards the edge of the nucleus in Roberts cells. (B): Distribution of CB2 mutual position of normal and Roberts cells. The median was calculated both for normal cells (Mmn,black line) and Roberts cells (MmR, blue line). Mutual distances are expressed as a proportion of the diameter. Mmn = 0.4527 and MmR = 0.3813: Wilcoxon test was significant (alpha = 0.05) with a p value of 0.0829 showing a significant rapprochement of homologous PH1 territories in Roberts cells.

Mentions: Statistical investigations were performed on PH of chromosome 1 with CB2 probe. Difference in the radial position of PH1 was observed between normal and RBS cytotrophoblasts. Twenty-six RBS nuclei (52 PH1 territories) and 24 control nuclei (48 PH1 territories) were analyzed from cytotrophoblast. The distance of PH1 to the center of the nucleus was significantly increased in RBS nuclei (MrR = 0.6700) compared to controls (Mrn = 0.5285) (Figure 3A). This result was interpreted as a localization of PH1 more peripheral in RBS nuclei than in normal cells. There was also a statistically significant difference between normal and RBS cells with respect to mutual PH1 distances (Figure 3B). We observed that in RBS nuclei, both homologous PH1 territories were closer (MmR = 0.3813) to each other than in normal cells (Mmn = 0.4527) (Wilcoxon test). The same analysis was performed on fibroblasts. We were able to analyze 8 RBS nuclei (16 CB2 territories) and 16 control nuclei (31 CB2 territories). No statistically significant difference in the radial position of PH1 was observed between normal and RBS fibroblasts but a general trend towards a more peripheral location of these territories was noticed for RBS fibroblasts (MrR = 0.6213 and Mrn = 0.5562).Figure 3


3D-FISH analysis reveals chromatid cohesion defect during interphase in Roberts syndrome.

Dupont C, Bucourt M, Guimiot F, Kraoua L, Smiljkovski D, Le Tessier D, Lebugle C, Gerard B, Spaggiari E, Bourdoncle P, Tabet AC, Benzacken B, Dupont JM - Mol Cytogenet (2014)

Statistical representation of CB2 radial and mutual positions. (A): Distribution of each PH1 (=CB2 probe) radial position of normal cells (black rings) and Roberts cells (blue triangles). The median was calculated both for normal cells (Mrn, black line) and Roberts cells (MrR, blue line). Radial distances are expressed as a proportion of the radius. Mrn = 0.5285 and MrR = 0.6700: Wilcoxon test was significant (alpha = 0.05) with a p value of 0.0018 showing a significant relocation of PH1 territory towards the edge of the nucleus in Roberts cells. (B): Distribution of CB2 mutual position of normal and Roberts cells. The median was calculated both for normal cells (Mmn,black line) and Roberts cells (MmR, blue line). Mutual distances are expressed as a proportion of the diameter. Mmn = 0.4527 and MmR = 0.3813: Wilcoxon test was significant (alpha = 0.05) with a p value of 0.0829 showing a significant rapprochement of homologous PH1 territories in Roberts cells.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4197286&req=5

Fig3: Statistical representation of CB2 radial and mutual positions. (A): Distribution of each PH1 (=CB2 probe) radial position of normal cells (black rings) and Roberts cells (blue triangles). The median was calculated both for normal cells (Mrn, black line) and Roberts cells (MrR, blue line). Radial distances are expressed as a proportion of the radius. Mrn = 0.5285 and MrR = 0.6700: Wilcoxon test was significant (alpha = 0.05) with a p value of 0.0018 showing a significant relocation of PH1 territory towards the edge of the nucleus in Roberts cells. (B): Distribution of CB2 mutual position of normal and Roberts cells. The median was calculated both for normal cells (Mmn,black line) and Roberts cells (MmR, blue line). Mutual distances are expressed as a proportion of the diameter. Mmn = 0.4527 and MmR = 0.3813: Wilcoxon test was significant (alpha = 0.05) with a p value of 0.0829 showing a significant rapprochement of homologous PH1 territories in Roberts cells.
Mentions: Statistical investigations were performed on PH of chromosome 1 with CB2 probe. Difference in the radial position of PH1 was observed between normal and RBS cytotrophoblasts. Twenty-six RBS nuclei (52 PH1 territories) and 24 control nuclei (48 PH1 territories) were analyzed from cytotrophoblast. The distance of PH1 to the center of the nucleus was significantly increased in RBS nuclei (MrR = 0.6700) compared to controls (Mrn = 0.5285) (Figure 3A). This result was interpreted as a localization of PH1 more peripheral in RBS nuclei than in normal cells. There was also a statistically significant difference between normal and RBS cells with respect to mutual PH1 distances (Figure 3B). We observed that in RBS nuclei, both homologous PH1 territories were closer (MmR = 0.3813) to each other than in normal cells (Mmn = 0.4527) (Wilcoxon test). The same analysis was performed on fibroblasts. We were able to analyze 8 RBS nuclei (16 CB2 territories) and 16 control nuclei (31 CB2 territories). No statistically significant difference in the radial position of PH1 was observed between normal and RBS fibroblasts but a general trend towards a more peripheral location of these territories was noticed for RBS fibroblasts (MrR = 0.6213 and Mrn = 0.5562).Figure 3

Bottom Line: Mutations in the ESCO2 (establishment of cohesion 1 homolog 2) gene located in 8p21.1 have been found in several families.ESCO2, a member of the cohesion establishing complex, has a role in the effective cohesion between sister chromatids.These changes may modify interactions between the chromatin and the proteins associated with the inner nuclear membrane or the pore complexes.

View Article: PubMed Central - PubMed

Affiliation: Unité fonctionnelle de Cytogénétique-Département de Génétique- APHP, Hôpital Robert Debré, 48 Bd Sérurier, 75935 Paris, France.

ABSTRACT

Background: Roberts syndrome (RBS) is a rare autosomal recessive disorder mainly characterized by growth retardation, limb defects and craniofacial anomalies. Characteristic cytogenetic findings are "railroad track" appearance of chromatids and premature centromere separation in metaphase spreads. Mutations in the ESCO2 (establishment of cohesion 1 homolog 2) gene located in 8p21.1 have been found in several families. ESCO2, a member of the cohesion establishing complex, has a role in the effective cohesion between sister chromatids. In order to analyze sister chromatids topography during interphase, we performed 3D-FISH using pericentromeric heterochromatin probes of chromosomes 1, 4, 9 and 16, on preserved nuclei from a fetus with RBS carrying compound heterozygous mutations in the ESCO2 gene.

Results: Along with the first observation of an abnormal separation between sister chromatids in heterochromatic regions, we observed a statistically significant change in the intranuclear localization of pericentromeric heterochromatin of chromosome 1 in cells of the fetus compared to normal cells, demonstrating for the first time a modification in the spatial arrangement of chromosome domains during interphase.

Conclusion: We hypothesize that the disorganization of nuclear architecture may result in multiple gene deregulations, either through disruption of DNA cis interaction -such as modification of chromatin loop formation and gene insulation - mediated by cohesin complex, or by relocation of chromosome territories. These changes may modify interactions between the chromatin and the proteins associated with the inner nuclear membrane or the pore complexes. This model offers a link between the molecular defect in cohesion and the complex phenotypic anomalies observed in RBS.

No MeSH data available.


Related in: MedlinePlus