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Trichostatin A treatment of cloned mouse embryos improves constitutive heterochromatin remodeling as well as developmental potential to term.

Maalouf WE, Liu Z, Brochard V, Renard JP, Debey P, Beaujean N, Zink D - BMC Dev. Biol. (2009)

Bottom Line: However, abnormal nuclear remodeling was frequently observed after SCNT, in association with low developmental efficiency.When transient treatment with the histone deacetylase inhibitor trichostatin A (TSA) was tested, we observed improved nuclear remodeling in 1-cell SCNT embryos that correlated with improved rates of embryonic development at subsequent stages.Together, the results suggest that proper organization of constitutive heterochromatin in early embryos is involved in the initial developmental steps and might have long term consequences, especially in cloning procedures.

View Article: PubMed Central - HTML - PubMed

Affiliation: INRA, UMR 1198 Biologie du Développement et Reproduction, Jouy en Josas, France. walidemaalouf@yahoo.co.uk

ABSTRACT

Background: Genome reprogramming in early mouse embryos is associated with nuclear reorganization and particular features such as the peculiar distribution of centromeric and pericentric heterochromatin during the first developmental stage. This zygote-specific heterochromatin organization could be observed both in maternal and paternal pronuclei after natural fertilization as well as in embryonic stem (ES) cell nuclei after nuclear transfer suggesting that this particular type of nuclear organization was essential for embryonic reprogramming and subsequent development.

Results: Here, we show that remodeling into a zygotic-like organization also occurs after somatic cell nuclear transfer (SCNT), supporting the hypothesis that reorganization of constitutive heterochromatin occurs regardless of the source and differentiation state of the starting material. However, abnormal nuclear remodeling was frequently observed after SCNT, in association with low developmental efficiency. When transient treatment with the histone deacetylase inhibitor trichostatin A (TSA) was tested, we observed improved nuclear remodeling in 1-cell SCNT embryos that correlated with improved rates of embryonic development at subsequent stages.

Conclusion: Together, the results suggest that proper organization of constitutive heterochromatin in early embryos is involved in the initial developmental steps and might have long term consequences, especially in cloning procedures.

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Percentages of embryos displaying pronuclei with more than 3 centromeres not associated with NPBs. Embryos were assessed at the late 1-cell stage: 26 hphCG for fertilized embryos, 10 hpa for ESNT and SCNT embryos (with or without transient TSA treatment). Groups labeled with an asterisk are statistically different from the "fertilized embryos" group (p < 0.05).
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Figure 2: Percentages of embryos displaying pronuclei with more than 3 centromeres not associated with NPBs. Embryos were assessed at the late 1-cell stage: 26 hphCG for fertilized embryos, 10 hpa for ESNT and SCNT embryos (with or without transient TSA treatment). Groups labeled with an asterisk are statistically different from the "fertilized embryos" group (p < 0.05).

Mentions: The zygote-specific nuclear organization observed during the first cell cycle of mouse embryos obtained by natural fertilization is characterized by the association of centromeres with the peripheries of nucleolar precursor bodies (NPBs, Figure 1b-arrowhead). We previously showed that about 80% of embryos obtained by natural fertilization display at most 3 centromeres not associated with NPB peripheries (Figure 2, [17]). Interestingly, this percentage is significantly decreased in 1-cell embryos produced by nuclear transfer of ES cells (ESNT) (~60%, p < 0.05) and correlates with the percentage of embryos that fail to develop into blastocysts [17]. In order to further address the relationship between nuclear remodeling and developmental potential, we investigated embryos produced by nuclear transfer of cumulus cells (SCNT), and analyzed the distribution of centromeric and pericentric heterochromatin during the first cell cycles. We therefore used immunofluorescent detection of heterochromatin protein 1β (HP1β), strongly enriched at pericentric heterochromatin, and of CENP proteins localized within the centromeres.


Trichostatin A treatment of cloned mouse embryos improves constitutive heterochromatin remodeling as well as developmental potential to term.

Maalouf WE, Liu Z, Brochard V, Renard JP, Debey P, Beaujean N, Zink D - BMC Dev. Biol. (2009)

Percentages of embryos displaying pronuclei with more than 3 centromeres not associated with NPBs. Embryos were assessed at the late 1-cell stage: 26 hphCG for fertilized embryos, 10 hpa for ESNT and SCNT embryos (with or without transient TSA treatment). Groups labeled with an asterisk are statistically different from the "fertilized embryos" group (p < 0.05).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2656487&req=5

Figure 2: Percentages of embryos displaying pronuclei with more than 3 centromeres not associated with NPBs. Embryos were assessed at the late 1-cell stage: 26 hphCG for fertilized embryos, 10 hpa for ESNT and SCNT embryos (with or without transient TSA treatment). Groups labeled with an asterisk are statistically different from the "fertilized embryos" group (p < 0.05).
Mentions: The zygote-specific nuclear organization observed during the first cell cycle of mouse embryos obtained by natural fertilization is characterized by the association of centromeres with the peripheries of nucleolar precursor bodies (NPBs, Figure 1b-arrowhead). We previously showed that about 80% of embryos obtained by natural fertilization display at most 3 centromeres not associated with NPB peripheries (Figure 2, [17]). Interestingly, this percentage is significantly decreased in 1-cell embryos produced by nuclear transfer of ES cells (ESNT) (~60%, p < 0.05) and correlates with the percentage of embryos that fail to develop into blastocysts [17]. In order to further address the relationship between nuclear remodeling and developmental potential, we investigated embryos produced by nuclear transfer of cumulus cells (SCNT), and analyzed the distribution of centromeric and pericentric heterochromatin during the first cell cycles. We therefore used immunofluorescent detection of heterochromatin protein 1β (HP1β), strongly enriched at pericentric heterochromatin, and of CENP proteins localized within the centromeres.

Bottom Line: However, abnormal nuclear remodeling was frequently observed after SCNT, in association with low developmental efficiency.When transient treatment with the histone deacetylase inhibitor trichostatin A (TSA) was tested, we observed improved nuclear remodeling in 1-cell SCNT embryos that correlated with improved rates of embryonic development at subsequent stages.Together, the results suggest that proper organization of constitutive heterochromatin in early embryos is involved in the initial developmental steps and might have long term consequences, especially in cloning procedures.

View Article: PubMed Central - HTML - PubMed

Affiliation: INRA, UMR 1198 Biologie du Développement et Reproduction, Jouy en Josas, France. walidemaalouf@yahoo.co.uk

ABSTRACT

Background: Genome reprogramming in early mouse embryos is associated with nuclear reorganization and particular features such as the peculiar distribution of centromeric and pericentric heterochromatin during the first developmental stage. This zygote-specific heterochromatin organization could be observed both in maternal and paternal pronuclei after natural fertilization as well as in embryonic stem (ES) cell nuclei after nuclear transfer suggesting that this particular type of nuclear organization was essential for embryonic reprogramming and subsequent development.

Results: Here, we show that remodeling into a zygotic-like organization also occurs after somatic cell nuclear transfer (SCNT), supporting the hypothesis that reorganization of constitutive heterochromatin occurs regardless of the source and differentiation state of the starting material. However, abnormal nuclear remodeling was frequently observed after SCNT, in association with low developmental efficiency. When transient treatment with the histone deacetylase inhibitor trichostatin A (TSA) was tested, we observed improved nuclear remodeling in 1-cell SCNT embryos that correlated with improved rates of embryonic development at subsequent stages.

Conclusion: Together, the results suggest that proper organization of constitutive heterochromatin in early embryos is involved in the initial developmental steps and might have long term consequences, especially in cloning procedures.

Show MeSH