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Small-angle neutron and X-ray scattering data for HeLa nuclei with the normal and suppressed transcription activities are reported. Small-angle neutron scattering data demonstrate the presence of a bifractal structure inside a nucleus. The logarithmic fractal structure is observed in the range from the size of the nucleus to several hundreds of nanometer, whereas the volume fractal structure exists at smaller scales down to a nucleosome structure. Small-angle X-ray scattering data show that the presence of the volume fractal structure correlates with the transcription activity of a cell. In view of the successful description of chromatin by the fractal globule model (Hi–C method data), a scenario for the formation of the bifractal structure inside the nucleus has been proposed. A system of transport channels (logarithmic fractal) is located inside close-packed chromatin, whereas active chromatin is localized near transport channels or inside them and forms volume fractal structures due to the transcription activity. Thus, the logarithmic fractal structure ensures the uniform distribution of voids at various scales, which is potentially necessary for the transcription and transport of substances inside the nucleus, whereas the volume fractal structure is due to the transcription activity of the cell. [ABSTRACT FROM AUTHOR]

Neutrophils are the leading cells of the innate immune system and the main population of leukocytes responsible for the primary reaction of the body to various infectious particles. The latter are destroyed by neutrophils due to the processes of phagocytosis and a cascade of reactions, including a respiratory burst reaction. As a result of the respiratory burst reaction of neutrophils they produce reactive oxygen and halogen species, powerful cytotoxic agents that destroy particles in the phagolysosome. All of these processes require regulation, because overactivation of neutrophils can lead to the damage of the tissues surrounding the focus of inflammation mediated by the reactive forms of oxygen. Proteins of the acute phase of inflammation claim for the role of inflammatory regulators. Previously, we have shown the participation of ceruloplasmin in inhibiting the respiratory burst reaction of neutrophils in blood samples. Fibrinogen, on the contrary, increased the intensity of the respiratory burst reaction. Not for all proteins of the acute phase of inflammation and especially their combinations, the effect on the functions of neutrophils has been studied in detail. In this work the effect of a number of proteins of the acute phase of inflammation (C-reactive protein, serum amyloid A, alpha-1-acid glycoprotein and fibrinogen) on the ability of peripheral blood neutrophils to the respiratory burst reaction was studied for the first time using flow cytometry with the registration of the production of reactive oxygen species in cells of peripheral blood samples. Significant changes in the ability of neutrophils to produce reactive oxygen species were found for a number of combinations of the studied proteins of the acute phase of inflammation. The study of interactions of ceruloplasmin and fibrinogen with peripheral blood neutrophils revealed their membrane localization. It seems promising to identify receptors for proteins of the acute phase of inflammation on the neutrophil membrane. [ABSTRACT FROM AUTHOR]

The HeLa cell's nuclei surface landscape, which appeared after the mechanical deformation, was studied by atomic-force microscopy. Nuclei were isolated from HeLa-line cells, and deformed under centrifugal forces, followed by fixation with glutaraldehyde. The resulting landscape was shown to be mainly due to the high chromatin resistance to deformation. This stability correlates with DNA supercoiling. Cells' treatment with topoisomerase inhibitors I and II leads to the relaxation of supercoiling and significant flattening of the nuclei. On the contrary, cells' treatment with a DNA intercalator leads to an increase in the DNA rigidity and, as a result, the resistance of chromatin to mechanical deformation. Thus, the observed changes in morphology reflect the functional features of the cell nucleus. [ABSTRACT FROM AUTHOR]

Stochastic gene expression can play an important role in the fate of both each specific cell and the cell population as a whole. In this work, we demonstrate significant variability of p53 expression, up to its complete absence, in human primary glioblastoma cells, which is not observed in cells of normal FLEH fibroblasts and transferable tumour cell lines, such as HeLa and HT1080. At the same time, the variability of p53 expression in cells depends on the density of seeding. We show that when the transcription is suppressed with actinomycin D or the p53 gene is knocked down by RNA interference, the restoration of its expression level in cells proceeds stochastically. [ABSTRACT FROM AUTHOR]

In this study, we present a model for visualization of the exosome transfer of p53-GFP protein between cultured mammalian cells. The temporal parameters of the accumulation of fluorescent labeled protein in recipient cells have been analyzed. We employed HEK293 cells transfected with p53∆Y126-GFP plasmid (a GFP clone) as donor of the exosomes, while the original HEK293 cell line was used as a recipient. Our results provide evidence that the transfer of the GFP protein from cell to cell is carried out via exosomes. It has been shown that the accumulation of this protein by the recipient cells in cocultures of these cells takes a prolonged time. The temporal parameters of this transfer differ between the cells within the same population. [ABSTRACT FROM AUTHOR]

Exosomes are nanosized vesicles that are secreted by many types of cells. We have found that exosomes secreted by HEK293 and HT-1080 can suppress growth and proliferation of p53-deficient cells. Upon overexpression of exogenous p53-GFP in HEK293 cells, we observed p53 protein in exosomes that were secreted by these cells. We also found endogenous p53 in exosomes that were secreted by HT-1080 cells with a higher level of p53 expression. We were able to detect endogenous p53 protein in exosomes that originated from human plasma and were transferred to p53-deficient cells. Our findings indicate that p53 protein can be transferred between cells and may play an important physiological role. [ABSTRACT FROM AUTHOR]