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I V Guzhova

Publications and source records attributed to I V Guzhova.

13 recordsLinked to original sources
PubMed2000

[Stress proteins in eukaryotic cells].

The review concerns properties and function of heat shock proteins (hsp) in the eukaryotic cell. The factors inducing Hsps' expression are considered with the emphasis on the fact that most of these agents are able to affect the function of peptide-synthesizing and protein-modifying machineries. The common outcome of this effect is accumulation of wrongly assembled protein structures which results in activation of heat shock transcription factors. The major property of proteins belonging to Hsp70 and Hsp90 is their chaperonic activity or the ability to bind newly synthesized or damaged polypeptides followed by restoration of the native structure of the latter. In this activity Hsp70 and Hsp90 are assisted by other proteins, and the work of such chaperonic systems is described. The function of the major stress protein Hsp70 in the eukaryotic cell was analysed, and on the base of a huge amount of data in has been resumed that proteins of this family constitute one of the most abundant systems of cell protection against cytotoxic factors. In the concluding part of the review we present some ways of application of our knowledge of Hsp in ecology, for analysing biological pollution, and in medicine, for increasing tissue or organismal resistance to injuring factors.

Bacteria↗
PubMed2000

[Induction and accumulation of HSP70 leads to formation of its complexes with other cell proteins].

The expression of a major stress protein Hsp70 may be induced by a great number of cytotoxic agents and also by factors known to cause process of cell proliferation or apoptosis. After induction the synthesis of Hsp70 is reduced to its basic level within first 2-6 hours after inducer application, while the high content of the protein may persist up to several days. The aim of this study was to understand the reason of such a long storage of Hsp70 in U-937 cells induced with three distinct factors. The data of immunoblotting showed that the mild heat shock at 43 degrees C for 60 min, phorbol ester and tumor necrosis factor (the two latter known to induce differentiation and apoptosis, respectively) caused Hsp70 accumulation, the protein level being high within 48 hours and then slowly declined to the basal level. According to the results of chromatography on anti-Hsp70 antibody-Sepharose gel, approximately 50% of the protein was retarded by the gel, while the other part was not recognized by immunoglobulins. Among proteins bound to the Hsp70, three polypeptides were identified as actin, p65 and c-Rel, two latter being constituents of NF-kappa B regulatory complex. The data demonstrate that besides its traditional target, i.e. newly synthesized or abnormal polypeptides, Hsp70 is able to bind mature, active proteins.

Chromatography, Affinity↗
PubMed2000

[Effect of heat shock on cell differentiation and apoptosis in U-937 cells].

One of the most abundant cell protective systems is based on an inducible member of Hsp70 family of stress proteins. Proteins belonging to the family are known to participate in all processes of cell physiology including differentiation and apoptosis. Here data are presented concerning effect of heat shock accompanied by a high-level accumulation of Hsp70 on the phorbol ester-induced expression of surface antigens and on TNF-alpha mediated apoptosis. The data showed that heat shock at 43 degrees C for 60 min reduced the expression of CD11c and CD23 surface markers pre-established by phorbol ester; the latter is known to induce macrophage-like phenotype by 70-80% of the original level. Heating in the same conditions was also shown to markedly delay the outcome of apoptosis stimulated by TNF-alpha. Suggesting that Hsp70 by its binding transcription activators of NF-kappa B complex might transiently suppress both the processes, we determined the amount of p65 and c-Rel in nuclear fractions of cells subjected to various stimuli. It was found that both proteins were retarded in the cytoplasm and were not transported to nuclei in cells heated before the administration of PMA or TNF. It is concluded that Hsp70 accumulating in higher amounts is able to transiently protect cells of TNF-mediated cytotoxic effect by physical association with the proteins that serve as modulators of apoptosis.

Apoptosis↗
PubMed2000

[Induction of apoptosis in murine myeloma cells NS0/1, transfected with the gene for the basic heat shock protein HSP70i].

Murine myelomas are rare cell variants deficient in inducible isoform of Hsp70 that protects cells from injury. In these cells Hsp70 is absent and is not induced under stress conditions. In this study myeloma cells NS0/1 were transfected with hsp70, and their susceptibility to apoptosis was challenged by serum deprivation or hydrogen peroxide. Expression of Hsp70 in NS0/1 cells made them more resistant to apoptosis in serum-free medium but did not affect their response to hydrogen peroxide. Hsp70 involvement in the protection of myeloma cells from apoptosis caused by different agents is discussed.

Animals↗
PubMed1998

Effects of exogenous stress protein 70 on the functional properties of human promonocytes through binding to cell surface and internalization.

The presence of antibodies against the major stress protein, Hsp70, in patients with autoimmune diseases led us to hypothesize that Hsp70 may occur extracellularly, and could exert chaperoning and regulatory effects on various cells. We examined the action of pure Hsp/Hsc70 on the main physiological functions of human promonocytic U-937 cells. The protein was isolated from calf muscle and was shown to be a mixture of inducible Hsp70 (60%) and constitutive Hsc70 (40%) isoforms. It was observed that the addition of the protein up-regulated two major monocyte/macrophage differentiation markers, CD11c and CD23, by 20-35%, while it had no effect on CD14. The experiments performed to investigate the influence of Hsp/Hsc70 on the reaction of U-937 cells to differentiation stimuli demonstrated that the addition of the protein prior to PMA was able to inhibit binding of proper transcription factors to double-symmetry and cAMP-response elements of the c-fos early response gene promoter. Administration of exogenous Hsp/Hsc70 prior to treatment with the tumor necrosis factor-alpha significantly lowered the number of apoptotic and necrotic cells. In no case did the control protein, ovalbumin, taken in the same concentration give a comparable effect on U-937 cells. Since the Hsp/Hsc70 effects occurred within the first hour of co-incubation, and therefore they might be explained by its interaction with the cell surface, we assayed binding of the biotinylated protein to U-937 cells by immunoenzyme assay, flow cytometry and indirect immunofluorescence. Using these three techniques we were able to detect Hsp/Hsc70 bound to cells after a 20 min incubation. According to flow cytometry data, at this time 32% of cells were positively stained with streptavidin-FITC. Immunofluorescence studies demonstrated Hsp/Hsc70 bound to the cell surface after a 20 min incubation followed by induction of patch and cap-like structures. One hour later, the majority of the protein had been internalized by U-937 cells.

Animals↗
PubMed1997

Major stress protein Hsp70 interacts with NF-kB regulatory complex in human T-lymphoma cells.

Polypeptides belonging to the Hsp70 major stress protein family and to the NF-kB/Rel multi-functional regulatory complex are known to be involved in cellular defense mechanisms. It was suggested that both systems may interact in cells that respond to injuring stimuli. To check this, Molt4 human lymphoma cells were heated at 43 degrees C for 15 min and, after a 6 h post-shock recovery period, the cells were activated with phorbol ester or bacterial lipopolysaccharide. It was found that mild heat shock caused a substantial increase of the intracellular Hsp70 content with the concomitant suppression of NF-kB complexes, though the latter was properly activated in non-stressed cells. After a 24 h period of being inactive the complex fully recovered its activity and p65 and c-Rel subunits migrated to the nucleus. This new active period lasted even longer than that in non-heated control cells. As this suggested the existence of a Hsp70-related mechanism of NF-kB/Rel complex retention in cytoplasm, we carried out immunoprecipitation with the use of anti-Hsp70 and anti-Rel antibodies. All three Rel family members p65, c-Rel, p50, but not their precursors and IkB alpha inhibitory protein were shown to co-precipitate with the stress protein and anti-Hsp70 antibodies from both heated and non-heated cells. We conclude that the Hsp70 stress protein may confer a new mechanism of NF-kB regulation in cells affected by elevated temperature or other factors related to the cellular response to stress.

Blotting, Western↗
PubMed1992

Antibody against p58 surface antigen of RA-2 rat rhabdomyosarcoma cells inhibits their metastatic activity.

Antibodies generated against the whole membrane preparation isolated from rhabdomyosarcoma RA-2 cells were shown by immunoblotting and immunoaffinity chromatography to recognize 58-kDa polypeptide, p58. The latter was confirmed to be a surface molecule in a test of radioiodination of RA-2 membrane by lodogen. The antibodies added to a suspension of RA-2 cells before their inoculation into rats decreased metastatic activity 50-fold without any noticeable influence on RA-2 proliferation level and viability. The data indicate that masking of p58 surface antigen by antibodies could make RA-2 cells unable to form experimental metastases in lung. We suggest that p58 may participate in the specific recognition by RA-2 of lung endothelial cells.

Animals↗
PubMed1992

[Interclonal and interpopulational differences in the frequency of spontaneous karyotypic changes in cell populations of transplantable rat rhabdomyosarcoma RA-2].

Rat organospecific transplantable RA-2 rhabdomyosarcoma substrains RA-2H (high metastatic potential), RA-2L (low metastatic potential) and RA-2T (thermal resistance) were investigated using single cell cloning technique for frequency of micronucleated cells (FMC). Significant interclonal and interpopulational differences were established. Average FMC for RA-2H was 2.96 +/- 0.13%; 5.94 +/- 0.24% for RA-2L and 1.89 +/- 0.12% for RA-2T. Clones showed 5-10 times differences in FMC in each substrain. FMC versus growth time and clone size was studied in RA-2H: average FMC dropped from 2.7% on day 9 to 0.5% on day 20 after administration and the lowest values were recorded in larger clones at each stage. Perspectives of FMC studies in tumor cell populations are discussed.

Animals↗
PubMed1990

[Clonal analysis of karyotypic instability and metastatic potential in tumor cell populations].

Rat organospecific transplantable RA-2 rhabdomyosarcoma strains RA-2H and RA-2L were investigated using single cell cloning technique for "Micronuclear containing cell frequency" (MCF) and "Metastatic potential" (MP). The RA-2H was obtained from RA-2 during selection for increasing metastatic potential, whereas the RA-2L was the result of selection in opposite direction. MP was assessed by lung colony formation technique and in the case of RA-2H, it was one hundred times greater than in the case of RA-2L (2490 +/- 280 and 22 +/- 11 lung colonies i.v. after injection of 10 cells, respectively). Average MCE for RA-2H was 3 and for RA-2L 5.3%. Also, significant differences were observed between these substrains in percentage of anaphase and telophase cells with bridges and fragments (24 +/- 4 for RA-2H and 56 +/- 5% for RA-2L, P less than 0.05). The selection of RA-2H clones with high level of MCF was successful. In the population obtained MCF was increased up to 7.8% and MP decreased (79 +/- 44). So, the selection for decreasing of MP led to significant increase in genome instability characteristics and the selection for increasing of MCF--to the abrupt decline of MP, which proved the existence of negative correlation between these two characters in populations studied. It is concluded that correlation between malignancy and genome instability in tumor populations with different levels of malignancy is not, as a rule, positive.

Animals↗
PubMed1988

[Removal of surface antigens and changes in metastatic potential of transplantable rat rhabdomyosarcoma RA-2 cells].

Cells of rat rhabdomyosarcoma RA-2 selected for high metastatic potential and affinity to lung tissue were (125I)-labelled in the presence of iodogene. The spectrum of 125I-labelled cell surface antigens was investigated by SDS-PAGE. Radionuclide was incorporated by proteins (or glycoproteins) with molecular weight of 30, 36, 47, 57, 78, 90, 102, 124, 180 and 250 kDa. After incubation of cells with 0.05-0.2% triton X-100 solution all the proteins except for those with molecular weight of 47 and 57 kDa were washed off the cellular surface; metastatic potential (MP) of triton-100 treated cells was 10 times as low as that of intact cells.

Animals↗
PubMed1988

[Selection for a decrease in metastatic potential in a cell population of transplantable rat rhabdomyosarcoma RA-2].

The method of individual cloning was used for checking the reduction of metastatic potential (MP) in cell population of highly malignant rhabdomyosarcoma RA-2. In the course of 15 selection cycles MP was lowered by 10-15 times. These data enabled us to consider the MP value as a quantitative character of malignant cells with low heritability (the mean value of realized heritability coefficient is equal to 0.18).

Animals↗