Urogenital tuberculosis (TB) often leads to contraction of the bladder, a reduction of the urinary reservoir capacity, and, in the latest stage, to real microcystitis up to full obliteration. Bladder TB Stage 4 is unsuitable for conservative therapy, and cystectomy with subsequent enteroplasty is indicated. In this study, using a model of bladder TB in New Zealand rabbits, the therapeutic efficacy of the interstitial injection of autologous bone-derived mesenchymal stem cells (MSCs) combined with standard anti-TB treatment in the restoration of the bladder function was demonstrated. For analysis of the MSC distribution in tissues, the latter were labelled with superparamagnetic iron oxide nanoparticles. In vitro studies demonstrated the high intracellular incorporation of nanoparticles and the absence of cytotoxicity on MSC viability and proliferation. A single-dose administration of MSCs into the bladder mucosal layer significantly reduced the wall deformation and inflammation and hindered the development of fibrosis, which was proven by the subsequent histological assay. Confocal microscopy studies of the bladder cryosections confirmed the presence of superparamagnetic iron oxide nanoparticle-labelled MSCs in different bladder layers of the treated animals, thus indicating the role of stem cells in bladder regeneration.

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.

The Death-domain associated protein 6 (DAXX) is an evolutionarily conserved and ubiquitously expressed multifunctional protein that is implicated in many cellular processes, including transcription, cellular proliferation, cell cycle regulation, Fas-induced apoptosis, and many other events. In the nucleus, DAXX interacts with transcription factors, epigenetic modifiers, and chromatin-remodeling proteins such as the transcription regulator ATRX—the α-thalassemia/mental retardation syndrome X-linked ATP-dependent helicase II. Accordingly, DAXX is considered one of the main players involved in chromatin silencing and one of the most important factors that maintain integrity of the genome. In this brief review, we summarize available data regarding the general and specific functions of DAXX in mammalian early development, with special emphasis on the function of DAXX as a chaperone of the histone variant H3.3. Since H3.3 plays a key role in the developmental processes, especially in the pronounced rearrangements of heterochromatin compartment during oogenesis and embryogenesis, DAXX can be considered as an important factor supporting proper development. Specifically, loss of DAXX affects the recruitment of ATRX, transcription of tandem repeats and telomere functions, which results in a decrease in the viability of early embryos.

Interchromatin granule clusters (IGCs), also known as nuclear speckles, splicing factor compartments, or SC35-domains, are one of the most universal nuclear organelles of the cell. We have used two-cell mouse embryos as an experimental system to study the possible association of poly(A)(+) RNA and factors involved in RNA export (Tip-associated protein [TAP] and heterogenous nuclear ribonucleoprotein A/B [hnRNP A/B]) with IGCs. Poly(A)(+) RNA was localized by microinjections of 2'-O-Me(U)(22) probes conjugated with tetramethylrhodamine. RNA export proteins were detected by immunofluorescence confocal laser microscopy and immunogold-labeling electron microscopy. We found that poly(A)(+) RNA was located in IGCs regardless of the transcriptional state of the nuclei. hnRNP A/B was also found to characterize IGCs of the embryo nuclei with various levels of transcription activity. In transcriptionally active embryo nuclei, TAP was detected in the vicinity of IGCs rather than inside them; however, when transcription was inhibited by drugs, TAP was localized to IGCs. Our data support the idea that IGCs not only serve as splicing factor reservoirs, but also take part in mRNA retention and export.

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