Search PubMed⌕ Search

Biomedical subjects

I V Volkova

Publications and source records attributed to I V Volkova.

At least 19 recordsLinked to original sources
PubMed2006

[Specificity of changes in proteasome properties in diethylmaleate-induced apoptosis of K562 cells].

The participation of proteasome in the programmed cells death is now extensively investigated. Studies using selective inhibitors of proteasomes have provided a direct evidence of both pro- and anti-apoptotic functions of proteasomes. Such opposite roles of 26S proteasomes in regulation of apoptosis may be defined by the proliferative state of cell. The induction of apoptosis in K562 cells by diethylmaleate was used as a model to investigate changes in the subunit composition, phosphorylation state and enzymatic activities of 26S proteasomes undergoing the programmed cell death. Here we have shown that proteasomes isolated from the cytoplasm of control and diethylmaleate treated K562 cells differ in their subunit patterns, as well as in the phosphorylation state of subunits on threonine and tyrosine residues. It has been shown for the first time that proteolytic activity of 26S proteasomes is decreased, and endoribonuclease activity of 26S proteasomes is affected under diethylmaleate action on K562 cells. Treatment of K562 cells with an inductor of apoptosis--diethylmaleate--leads to modification of a proteasomal subunit (zeta/alpha5) associated with RNase activity of proteasomes. These data suggest the subunit composition and enzymatic activities of 26S proteasomes to be changed in K562 cells undergoing apoptosis, and that specific subtypes of 26S proteasomes participate in execution of programmed death of these cells.

Apoptosis↗
PubMed2005

[Phosphorylation of proteasomes and alpha-RNP from rat liver cells].

In eukaryotic cells the population of proteasomes is heterogeneous. Here we have shown that proteasomes from nuclei and cytoplasm of rat liver cells differ in their subunit patterns. The subunit pattern of alpha-RNP differs from that of proteasomes, however, alpha-RNP particles contain the number of 26S proteasome subunits. Moreover, the proteasomes contain subunits of alpha-RNP. We have shown for the first time that nuclear proteasomes and alpha-RNP are hyperphosphorylated on threonine residues. Differences in phosphorylation state of subunits of nuclear and cytoplasmic proteasomes and alpha-RNP on threonine and tyrosine residues have been revealed. A suggestion is put forward that hyperphosphorylation of subunits may determine nuclear localization of these complexes in rat liver cells. The results obtained suggest that a highly specialized system of protein kinases and phosphatases may be involved in the regulation of phosphorylation state of different populations of proteasomes and alpha-RNP in rat liver cells.

Animals↗
PubMed2005

[Effect of EGF on the activity of nuclear and cytoplasmic 26S proteasomes in A431 cells].

It has been first shown that EGF regulates a proteolytic activity of proteasomes. Following a 15 min action with 100 ng/ml EGF, three types of peptidase activity of both cytoplasmic and nuclear proteasomes were induced in A431 cells, although, this effect on different populations of proteasomes was selective. EGF preferentially stimulates chymotrypsin-like activity of cytoplasmic proteasomes, and induces a similar increase of chymotrypsin-like, trypsin-like and peptydylglutamyl peptide hydrolase activities of nuclear particles. Tyrphostin, an inhibitor of tyrosine kinase activity of EGF receptor, prevents the EGF effect on both proteolytic and RNase activity of nuclear and cytoplasmic proteasomes. It is concluded that EGF may rapidly and selectively stimulate enzymatic activity of EGF receptor.

Cell Line, Tumor↗
PubMed2004

[Selective effect of inductors of apoptosis on the endoribonuclease activity of 26S proteasomes and alpha-RNP particles in K562 cells: possible involvement of 26S proteasomes and alpha-RNP in the regulation of RNA stability].

It has been shown that endoribonuclease activity of alpha-RNP particles and 26S proteasomes are changed under the action of inductors of programmed cell death. Treatment of K562 cells with inductors of apoptosis--doxorubicin (adriamycin) and diethylmaleate--lead to a significant stimulation of RNAse activity of alpha-RNP and to reduction of proteasome RNase activity. The enzymatic activity under study has been shown to be specifically and selectively dependent on phosphorylation of subunits of alpha-RNP particles and 26S proteasomes. The characteristics of RNAse activity of different subpopulations of proteasomes differ. The specificity of a subpopulation of proteasomes exported from the cell has been demonstrated. Proteasome and alpha-RNP involvement in the coordinated control of stability of various specific messenger RNA molecules is suggested, and one of the mechanisms of this control might be the export of specific subpopulation of proteasomes from the cell.

Apoptosis↗
PubMed2004

[Selective effect of epidermal growth factor on the endoribonuclease activity of different subpopulations of proteasomes from A431 cell line. Specificity of extracellular proteasome population].

For the first time, it has been shown that population of proteasomes is heterogeneous in their RNAse activity. EGF exerts selective effect on different subpopulations of proteasomes. The RNAse activity of cytoplasmic proteasomes is induced under the influence of EGF on epidermoid carcinoma cell line A431. However, the activity of proteasomes isolated from culture medium and of nuclear proteasomes is inhibited by EGF. The above enzymatic activity has been shown to be specifically and selectively dependent on phosphorylation of proteasomal subunits in different subpopulations of proteasomes. Proteasome involvement in the coordinated control of specific messenger RNA molecules stability is suggested, and one of the mechanisms of this control might be an export of specific subpopulation of proteasomes from the cell.

Cell Line, Tumor↗
PubMed2003

[EGF regulation of specific endoribonuclease activity of 26S proteasomes from A431 cells: a potential role of proteasomes in control of mRNA stability].

For the first time it has been shown that RNase activity is induced under the influence of EGF on epidermoid carcinoma cell line A431. Proteasomes from EGF-treated A431 cells destabilize the 3'-untranslated regions of non-muscle beta actin mRNA, creating a specific cleavage pattern. In addition, these particles have been shown to specifically cleave Alu-containing informational RNA. The enzymatic activity under study has been shown to be dependent on phosphorylation of proteasomal subunits and specifically and selectively regulated by Ca and Mg ions. Proteasome involvement in the coordinated control of stability of specific messenger RNA molecules is suggested. The endoribonuclease activity of 26S proteasomes can constitute a link between EGF signaling pathways and RNA stability.

3' Untranslated Regions↗
PubMed2002

[Properties of endoribonuclease activity of proteasomes from K562 cells. II. Analysis of specific mRNA nucleolysis by proteasomes].

The ability of 26S proteasomes from the human proerythroleukaemic cell line K562 to degrade high-molecular-weight cytoplasmic RNAs, particularly specific messenger RNA, has been detected. The addition of hemin to K562 cells in the culture media leads to redistribution of proteasomes and their migration mainly to the cytoplasm. The human wild type p53 gene mRNA was shown to be specifically nucleolized by proteasomes. These particles displayed endoribonuclease activity towards mRNA for Renilla sp. luciferase. Proteasomes also specifically degraded Alu-containing mRNAs. A supposition is made about the involvement of proteasomes in stability control of specific RNA groups.

Alu Elements↗
PubMed2001

[Specific regulated endonuclease activity of small RNP, containing prosomes from the A431 cell line: possible mechanisms of regulating the stability of RNA by epidermal growth factor].

A comparative study was made of reactive oxygen species (ROS) in rat embryo fibroblasts and their transformants. Primary rat embryo fibroblasts (REF), REF transformed by the complementing oncogenes E1A plus cHa-ras (cell line E1A + Ras), and REF transformed by E1A plus E1B-19 kDa (cell line E1A + E1B) were studied. ROS generation was measured with microfluorometric assay using fluorescent probe 2',7'-dichlorofluorescin diacetate. It has been shown that the block of REF and E1A + 1B cells in the G1/S under serum-starved conditions (0.5% serum) for 24-48 h was paralleled by a decrease in ROS generation. Activation of serum-starved REF and E1A + 1B cells with 10% serum resulted in reactivation of cell cycle and gradual increase in ROS generation. The maximum intracellular level of ROS correlated in time with the phase of DNA synthesis. Serum-starved E1A + Ras cells were not stopped in the G1/S and ROS production of these cells was not dependent on serum growth factors. The prolonged cultivation of E1A + Ras cells in the medium with low serum content (0.5%) caused a sharp increase in ROS generation, which was accompanied by apoptotic death.

3' Untranslated Regions↗
PubMed2000

[Tissue specificity of subunit composition and EGF-dependent changes in the subunit pattern of 20S-proteasomes].

The subunit pattern of 20S proteasomes from rat kidney, rat liver, human A-431 cells, human K-562 cells and mouse NIH 3T3 cells were studied. Proteasomes in cells of a common tissue origin appeared to be similar, independently of the intensity of cell proliferation. Unlike, proteasomes in cells of various types of tissue specificity differed from each other. Besides, EGF was shown to induce changes in the subunit pattern of proteasomes in A-431 cells.

3T3 Cells↗
PubMed2000

[Novel endoribonuclease activity of 26S-proteasomes from A-431 cells].

Our analysis detected in 26S proteasomes of human A-431 cells a strong endoribonuclease activity, degrading cytoplasmic high-molecular-mass RNA, particularly, specific mRNAs. Enzymatic nature of this activity has been confirmed, and the optimal conditions studied. This endonuclease activity of proteasomes has not been earlier observed. Proteasome involvement in the stability control of specific messenger RNA molecules is suggested, and proteasome participation in the coordinated control of various stages of gene expression is discussed.

Endoribonucleases↗
PubMed1999

The specific endoribonuclease activity of small nuclear and cytoplasmic alpha-RNPs.

For the first time small nuclear ribonucleoprotein particles (alpha-RNP) tightly bound to chromatin as well as cytoplasmic alpha-RNP are shown to possess strong and regulated endonuclease activity specific for mRNAs and hnRNAs. The enzymatic nature of this activity is confirmed, and the optimal conditions detected. This RNase activity is controlled by the action of a differentiating stimulus, dimethylsulfoxide, in human K562 cells. Small alpha-RNP involvement in the coordinated control of stability of pre-messenger RNA and messenger RNA molecules is suggested.

Alu Elements↗
PubMed1998

[EGF-dependent association of 20S-proteasome and alpha-RNP particles with the epidermal growth factor receptor in A-431 cells].

Here we demonstrate that the epidermal growth factor (EGF) induces association of prosomes (20S-proteasomes) with its receptor in A-431 cells. Additionally, ligand-dependent association of ribonucleoprotein particles (alpha-RNP), containing small ALU-like RNA, with the EGF receptor was demonstrated. A suggestion has been put forward on the involvement of prosomes and alpha-RNP in the EGF signal transmission to different stages of gene expression.

Cysteine Endopeptidases↗
PubMed1983

[Changes in the proteins of the nuclear RNP particles of the rat liver stimulated by hydrocortisone].

A difference in the ratio of the two main components of information of the nuclear RNP-particles isolated from the liver of normal and cortisone-stimulated rats was found. Under the action of cortisone, the amount of high molecular component increased. An increase in the content of the low molecular proteins typical for poly A-containing RNP-particles was also observed after cortisone administration.

Animals↗