Nuclear distribution of the chromatin-remodeling protein ATRX in mouse early embryogenesis

Sailau, Zhuldyz K.; Bogolyubov, D. S.; Bogolyubova, I. O.

doi:10.1016/j.acthis.2016.11.001

Cited by 7 publications

(9 citation statements)

References 31 publications

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“…This point is well illustrated by the peculiarities of the distribution of ATRX protein being detectable at the periphery of only several NPBs (Sailau et al, 2017) (Fig. 5).…”

Section: Molecular Composition Of Different Npb-associated Heterochromentioning

confidence: 59%

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Peculiarities of the molecular composition of heterochromatin associated with pronucleoli in mouse embryos

2019

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The nucleus of pre-implantation mammalian embryos is characterized by peculiar structural organization. At the initial stages of cleavage, the nucleus of the embryo contains the so-called nucleolus precursor bodies (NPBs) or pronucleoli rather than functionally active nucleoli. The NPBs are fibrillar electron-dense structures inactive in RNA synthesis. The vast majority of NPBs are surrounded by a ring-shaped zone of transcriptionally inactive heterochromatin. Intriguingly, these zones contain not only tri-methylated histone Н3K9me3 as an epigenetic mark of repressed chromatin but also acetylated histone H4K5ac, a well-known marker of active chromatin. Immunocytochemical data suggest that the molecular composition of this ‘ring heterochromatin’ in mouse embryos changes during the realization of embryonic genome activation events, as well as during artificial suppression of transcription. In zygotes, some factors of mRNA biogenesis including splicing factor SC35 (SRSF2) and basal transcription factor TFIID are detectable in the ring chromatin. At later stages of development, other nuclear proteins such as Y14, a core component of the exon-exon junction complex (EJC), as well as the proteins involved in chromatin remodeling (ATRX, Daxx) are also detectable in this area. A typical component of the ‘ring heterochromatin’ is actin. Anti-actin immunocytochemical labeling is most expressed at the two-cell cleavage stage after activation of the embryonic genome. Indicatively, the molecular composition of the ‘ring heterochromatin’ associated with different NPBs may differ significantly even in the same nucleus. This seems to reflect the functional heterogeneity of morphologically similar NPBs according to their competence to the process of nucleologenesis. Here, we discuss briefly some peculiarities of the molecular composition and possible functions of the NPB-associated heterochromatin in mouse early embryos.

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“…This point is well illustrated by the peculiarities of the distribution of ATRX protein being detectable at the periphery of only several NPBs (Sailau et al, 2017) (Fig. 5).…”

Section: Molecular Composition Of Different Npb-associated Heterochromentioning

confidence: 59%

“…Note that ATRX is detectable in NPB-associated chromatin (arrows) only at the two-cell stage, and anti-ATRX staining is associated not with all NPBs. From (Sailau et al, 2017), with permission from Elsevier.…”

Section: Discussionmentioning

confidence: 99%

Peculiarities of the molecular composition of heterochromatin associated with pronucleoli in mouse embryos

2019

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“…Loss of maternal ATRX results in chromosome instability in mouse oocytes and early embryos [58]. In mouse embryogenesis, the dynamics of ATRX reflect the processes of nuclear reorganization related to the gradual activation of chromosomal transcription [59,60]. Genome inactivation in the final steps of R. temporaria karyosphere development can result in the accumulation of ATRX in extrachromosomal elements such as the KC.…”

Section: Discussionmentioning

confidence: 99%

The karyosphere capsule inRana temporariaoocytes contains structural and DNA-binding proteins

Ilicheva

Podgornaya

Bogolyubov

2018

Nucleus

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During the last stages of oogenesis, oocyte chromosomes condense and come close together, forming the so-called karyosphere. Karyosphere formation is accompanied by an essential decrease in transcriptional activity. In the grass frog Rana temporaria, the karyosphere is surrounded by an extrachromosomal capsule that separates the chromosomes from the rest of the nucleoplasm. The karyosphere capsule (KC) of R. temporaria has been investigated in detail at the ultrastructural level, but its protein composition remained largely unknown. We demonstrate here that nuclear actin, especially F-actin, as well as lamins A/C and B are the most abundant proteins of the KC. Key proteins of nuclear pore complexes, such as Nup93 and Nup35, are also detectable in the KC. New antibodies recognizing the telomere-binding protein TRF2 allowed us to localize TRF2 in nuclear speckles. We also found that the R. temporaria KC contains some proteins involved in chromatin remodeling, including topoisomerase II and ATRX. Thus, we believe that KC isolates the chromosomes from the rest of the nucleoplasm during the final period of oocyte growth (late diplotene) and represents a specialized oocyte nuclear compartment to store a variety of factors involved in nuclear metabolism that can be used in future early development.Abbreviations: BrUTP: 5-bromouridine 5’-triphosphate; CytD: cytochalasin D; IGCs: interchromatin granule clasters; IgG: immunoglobulin G; KC: karyosphere capsule; Mw: molecular weight; NE: nuclear envelope; PBS: phosphate buffered saline; SDS-PAGE: sodium dodecyl sulfate polyacrylamide gel electrophoresis; Topo II: topoisomerase II

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“…This association persists at the two-cell stage, when ATRX is localized both in the NPB-associated chromatin and in the chromocenters. In the morula stage, the ATRX distribution becomes diffusive [ 96 ].…”

Section: Chromatin Morphologymentioning

confidence: 99%

Heterochromatin Morphodynamics in Late Oogenesis and Early Embryogenesis of Mammals

Bogolyubova

Bogolyubov

2020

Cells

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During the period of oocyte growth, chromatin undergoes global rearrangements at both morphological and molecular levels. An intriguing feature of oogenesis in some mammalian species is the formation of a heterochromatin ring-shaped structure, called the karyosphere or surrounded “nucleolus”, which is associated with the periphery of the nucleolus-like bodies (NLBs). Morphologically similar heterochromatin structures also form around the nucleolus-precursor bodies (NPBs) in zygotes and persist for several first cleavage divisions in blastomeres. Despite recent progress in our understanding the regulation of gene silencing/expression during early mammalian development, as well as the molecular mechanisms that underlie chromatin condensation and heterochromatin structure, the biological significance of the karyosphere and its counterparts in early embryos is still elusive. We pay attention to both the changes of heterochromatin morphology and to the molecular mechanisms that can affect the configuration and functional activity of chromatin. We briefly discuss how DNA methylation, post-translational histone modifications, alternative histone variants, and some chromatin-associated non-histone proteins may be involved in the formation of peculiar heterochromatin structures intimately associated with NLBs and NPBs, the unique nuclear bodies of oocytes and early embryos.

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Nuclear distribution of the chromatin-remodeling protein ATRX in mouse early embryogenesis

Cited by 7 publications

References 31 publications

Peculiarities of the molecular composition of heterochromatin associated with pronucleoli in mouse embryos

Peculiarities of the molecular composition of heterochromatin associated with pronucleoli in mouse embryos

The karyosphere capsule inRana temporariaoocytes contains structural and DNA-binding proteins

Heterochromatin Morphodynamics in Late Oogenesis and Early Embryogenesis of Mammals

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