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Nuclear distribution of RNA polymerase II and mRNA processing machinery in early mammalian embryos.

Bogolyubova IO, Bogolyubov DS - Biomed Res Int (2014)

Bottom Line: Spatial distribution of components of nuclear metabolism provides a significant impact on regulation of the processes of gene expression.However, the period of cleavage is characterized by the most drastic and dynamic nuclear reorganizations accompanying zygotic gene activation.In this minireview, we try to summarize the results of studies concerning distribution of major factors involved in RNA polymerase II-dependent transcription, pre-mRNA splicing mRNA export that have been carried out on early embryos of mammals.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Cell Morphology, Institute of Cytology RAS, 4 Tikhoretsky Avenue, St. Petersburg 194064, Russia.

ABSTRACT
Spatial distribution of components of nuclear metabolism provides a significant impact on regulation of the processes of gene expression. While distribution of the key nuclear antigens and their association with the defined nuclear domains were thoroughly traced in mammalian somatic cells, similar data for the preimplantation embryos are scanty and fragmental. However, the period of cleavage is characterized by the most drastic and dynamic nuclear reorganizations accompanying zygotic gene activation. In this minireview, we try to summarize the results of studies concerning distribution of major factors involved in RNA polymerase II-dependent transcription, pre-mRNA splicing mRNA export that have been carried out on early embryos of mammals.

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Related in: MedlinePlus

The distribution of SR protein SC35 (a), (c), hyperphosphorylated RNA polymerase II (PolII) (b), (d) in control (a), (b), and arrested in vitro 2-cell mouse embryos (c), (d). Note the large SC35 speckles enriched in hyperphosphorylated RNA polymerase II in the nucleus of blocked embryo. Scale bar is 5 μm, according to [26], reprinted from Tissue and Cell; Bogolyubova. Transcriptional activity of nuclei in 2-cell blocked mouse embryos 2011; 43: 262-265 [26], with permission from Elsevier.
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fig2: The distribution of SR protein SC35 (a), (c), hyperphosphorylated RNA polymerase II (PolII) (b), (d) in control (a), (b), and arrested in vitro 2-cell mouse embryos (c), (d). Note the large SC35 speckles enriched in hyperphosphorylated RNA polymerase II in the nucleus of blocked embryo. Scale bar is 5 μm, according to [26], reprinted from Tissue and Cell; Bogolyubova. Transcriptional activity of nuclei in 2-cell blocked mouse embryos 2011; 43: 262-265 [26], with permission from Elsevier.

Mentions: In our immunocytochemical experiments, we used an affinity purified polyclonal serum to reveal the hyperphosphorylated form of RNAP II in mouse embryos. This form of RNAP II was detected before the major ZGA phase, namely, in early 2-cell embryos [24]. While ZGA proceeds, RNAP II was found in association with perichromatin fibrils (PFs) [25], which are referred to as the ultrastructural “in situ forms” of nascent pre-mRNA transcripts [55]. Besides, the hyperphosphorylated RNAP II was detected in nuclear speckles identified by the presence of the SR protein SC35. The intensity of anti-RNAP II immunostaining in speckles was being increased towards the end of ZGA [24] (Figure 1). If ZGA is delayed, for example, in embryos under the so-called “2-cell block in vitro” (for details, see [56, 57]), the hyperphosphorylated form of RNAP II begins to accumulate in enlarged nuclear speckles [26] (Figure 2).


Nuclear distribution of RNA polymerase II and mRNA processing machinery in early mammalian embryos.

Bogolyubova IO, Bogolyubov DS - Biomed Res Int (2014)

The distribution of SR protein SC35 (a), (c), hyperphosphorylated RNA polymerase II (PolII) (b), (d) in control (a), (b), and arrested in vitro 2-cell mouse embryos (c), (d). Note the large SC35 speckles enriched in hyperphosphorylated RNA polymerase II in the nucleus of blocked embryo. Scale bar is 5 μm, according to [26], reprinted from Tissue and Cell; Bogolyubova. Transcriptional activity of nuclei in 2-cell blocked mouse embryos 2011; 43: 262-265 [26], with permission from Elsevier.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4020508&req=5

fig2: The distribution of SR protein SC35 (a), (c), hyperphosphorylated RNA polymerase II (PolII) (b), (d) in control (a), (b), and arrested in vitro 2-cell mouse embryos (c), (d). Note the large SC35 speckles enriched in hyperphosphorylated RNA polymerase II in the nucleus of blocked embryo. Scale bar is 5 μm, according to [26], reprinted from Tissue and Cell; Bogolyubova. Transcriptional activity of nuclei in 2-cell blocked mouse embryos 2011; 43: 262-265 [26], with permission from Elsevier.
Mentions: In our immunocytochemical experiments, we used an affinity purified polyclonal serum to reveal the hyperphosphorylated form of RNAP II in mouse embryos. This form of RNAP II was detected before the major ZGA phase, namely, in early 2-cell embryos [24]. While ZGA proceeds, RNAP II was found in association with perichromatin fibrils (PFs) [25], which are referred to as the ultrastructural “in situ forms” of nascent pre-mRNA transcripts [55]. Besides, the hyperphosphorylated RNAP II was detected in nuclear speckles identified by the presence of the SR protein SC35. The intensity of anti-RNAP II immunostaining in speckles was being increased towards the end of ZGA [24] (Figure 1). If ZGA is delayed, for example, in embryos under the so-called “2-cell block in vitro” (for details, see [56, 57]), the hyperphosphorylated form of RNAP II begins to accumulate in enlarged nuclear speckles [26] (Figure 2).

Bottom Line: Spatial distribution of components of nuclear metabolism provides a significant impact on regulation of the processes of gene expression.However, the period of cleavage is characterized by the most drastic and dynamic nuclear reorganizations accompanying zygotic gene activation.In this minireview, we try to summarize the results of studies concerning distribution of major factors involved in RNA polymerase II-dependent transcription, pre-mRNA splicing mRNA export that have been carried out on early embryos of mammals.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Cell Morphology, Institute of Cytology RAS, 4 Tikhoretsky Avenue, St. Petersburg 194064, Russia.

ABSTRACT
Spatial distribution of components of nuclear metabolism provides a significant impact on regulation of the processes of gene expression. While distribution of the key nuclear antigens and their association with the defined nuclear domains were thoroughly traced in mammalian somatic cells, similar data for the preimplantation embryos are scanty and fragmental. However, the period of cleavage is characterized by the most drastic and dynamic nuclear reorganizations accompanying zygotic gene activation. In this minireview, we try to summarize the results of studies concerning distribution of major factors involved in RNA polymerase II-dependent transcription, pre-mRNA splicing mRNA export that have been carried out on early embryos of mammals.

Show MeSH
Related in: MedlinePlus