when H2B showed a H2A-like aggregated pattern in the nuclei The cytoplasmic accumulation of H2B was confirmed also by mass spectrometric identification of elevated levels of H2B following Dox treatment in the dechromatinized samples Conclusions: Anthra cyclines are widely used anti-cancer drugs exhibiting pleiotropic effects At the chromatin level these include topoisomerase inhibition, DNA intercalation, aggregation of chromatin, histone eviction as well as direct binding to histones The above large-scale effects were detected already at Dox concentrations that overlap serum peak levels reached in the typical clinical setting and therefore can be a factor both in the anticarcinogenic mechanism and in the side-effects of this anthracyclin

The rigid skeleton formed by networks of A- and B-type lamins is responsible for maintaining the nucleus shape. Moreover, the change in the ratio of lamin proteins in its composition, apparently, is a key factor determining mechanical properties of the cell nucleus, in particular plasticity. In this paper, the effect of the component composition of the nuclear lamina on the resistance of cells to mechanical stress and on the cell motility was considered. Expression of mutant forms of lamin A is accompanied by changes in the distance between microdomains of lamins within the nuclear membrane, and its increased bubbling relative to wild-type cells and cells overexpressing lamin A is observed. An increased number of deformed nuclei are noted when exposed to osmotic shock. The assessment of the effect of a change in the molecular composition of the nuclear lamina due to an increase (decrease) in expression of lamin A, as well as the introduction of progerin in an experimental wound model, showed that there are no differences under conditions of unlimited space.

In this paper, we investigated the delivery efficiency of doxorubicin by magnetite nanoparticles with different shape to LNCaP and PC-3 prostate cancer cell lines. Cubic and spherical nanoparticles of magnetite were synthesized in organic medium and hydrophilized by non-ionic surfactant Pluronic F127—polyethylene-polypropylene oxide polymer. Doxorubicin was loaded into hydrophobic region of polymeric shell. We have observed that cytotoxicity and distribution of doxorubicin in cells changed significantly in case of drug loaded into nanoparticles in comparison with free doxorubicin. We have shown that this change is due to two main reasons: (1) slower internalization of nanoparticles by cells compared to free doxorubicin and (2) slow and incomplete release of doxorubicin from nanoparticle polymer shell. Interestingly, nanoparticle shape influenced cytotoxicity and the dynamics of drug accumulation inside cancer cells. We have found that doxorubicin-loaded cubic nanoparticles were more toxic for both cell lines compared to spherical ones. Moreover, doxorubicin from cubic nanoparticles accumulated in cells faster than the drug loaded in spherical nanoparticles. So, our work shows that for efficient drug delivery, not only size and coating should be taken into account but also the shape of initial core as it plays an important role in nanoparticle interaction with cells.

We synthesized a fluorescence conjugate and modified magnetite-gold nanoparticles carrying prostate specific membrane antigen (PSMA) as the ligand. Analysis of their binding to human prostate cancer cell lines PC-3 (PSMA–) and LNCaP (PSMA+) showed selective interaction of the synthesized conjugate and modified nanoparticles with LNCaP cells. These findings suggest that these nanoparticles can be used in tissue-specific magnetic-resonance imaging.

It is considered that sister chromatids are held together immediately after replication by special protein complex--cohesin that consists of Smc1--Smc3 core dimer and two additional subunits, Scc1 and Scc3. This process is called cohesion. We have characterized binding of cohesin complex to early- and late-replicated chromatin at different stages of the cell cycle in human cells HeLa and HT1080 using superresolution microscopy (based on Structural ilumination microscopy--SIM) and immunoelectron microscopy. It has been shown that cohesins do not play important role in cohesion of heterochromatic domains, but they provide cohesion and organization of subdomains in euchromatic regions.

Due to a tight attachment of peripheral heterochromatin to the nuclear lamina its replication is connected with inevitable topological hindrances. Additional hindrances are caused by high stability of the lamina that complicates the access of replication factors to DNA duplication sites under conditions of highly condensed matrix with limited mobility. The work focuses on detailed study of structural organization and dynamics of the lamina in respect to replication of peripheral heterochromatin that is attached to it. The study of mobile properties of lamins at various stages of the S-phase using live cell imaging and super-resolution microscopy showed the absence of the dependence of lamins’ mobility on replicative status of attached heterochromatin. These data confirm the hypothesis on regulation of linkage between chromatin and lamina at the level of molecular intermediates. It has been shown at the ultrastructural level that possible temporary disruption in molecular bonds between the lamina and peripheral chromatin during replication does not cause movement of replicated domains from the nuclear periphery.

Sister chromatids are considered to be held together from just after replication until the beginning of compaction in prophase via a specific complex—cohesin consisting of Smc1-Smc3 dimer and two additional subunits Scc1 and Scc3, the process being referred to as “cohesion.” We have characterized peculiarities of binding of the cohesin complex with early and late replicating chromatin at various stages of the cell cycle in human cell lines HeLa and HT1080 using structured illumination microscopy and immune electron microscopy. It has been shown that cohesion in heterochromatic domains is evidently provided without the participation of cohesins, while the majority of cohesins bound to chromatin provides cohesion and subdomain organization in euchromatin.

Tight association of peripheral chromatin with nuclear lamina unavoidably creates topological constraints during replication. Additional complications are associated with high stability of lamina meshwork, which may hinder an access of replication factors to the sites of DNA synthesis in highly condensed template with limited mobility. In the current work we studied structural organization and dynamics of lamina as a function of replicative status of associated peripheral heterochromatin. The studies of molecular mobility of laminas at various stages of S-phase in vivo and using super-resolution microscopy showed no correlation between lamina dynamics and replicative status of attached heterochromatin. These data support the hypothesis that lamina-chromatin interactions during S-phase are regulated at the level of adapter proteins. Ultrastructural studies have demonstrated that temporal break of lamina-chromatin connections during replication does not cause noticeable spatial separation of replicating domains from nuclear periphery.

Noncoding and repetitive sequences make up a large part of the genome of high eukaryotes, but the elucidation of their roles and mechanisms of action are poorly understood. In this work, we found that interstitial telomeric repeats in the genome of Danio rerio colocalize with repetitive elements, including hAT and EnSpm, which are widely represented in vertebrate genomes. The investigation of a genomic region containing two pairs of these repeats located in close proximity showed that the area is transcribed. RNA-dependent structures containing this sequence were identified in D. rerio fibroblast nuclei, which indicates the functional importance of genomic repetitive elements or their transcripts.