[Semi-centennial history of the nuclear matrix at the turn of the 21st century].

In 1974, Berezney and Coffey described what they called the nuclear matrix (NM), thus ignoring our priority, since we had isolated and characterized virtually the same skeletal structure 25 years before this discovery. The presence of NM in the live cell was doubted, because of unsuccessful attempts to recognize it in vivo. NM comprises the lamina, extracted nucleoli and an intranuclear fibrogranular network.

[Proteins of the nuclear matrix and their phosphorylation in normal and tumor cells].

The protein composition of the nuclear matrix of normal and tumor cells is discussed. A characteristic feature of the latter is the predominance of high molecular weight polypeptides containing mainly glyco- and phosphoproteins. Only few of them are identified.

[Effect of colostrum polypeptide on structure and lipid peroxidation in liver nuclei of rats late after gamma-irradiation].

Rats were irradiated by 8Gr in a doze power of 2.33 R per second. A portion of animals were injected subcutaneously with a cow colostrum polypeptide (CP) in a doze of 1 mg per g of body weight before the irradiation and daily after the irradiation during 4 days.

[The immunochemical demonstration of high-molecular proteins in the nuclear matrix of tumor cells].

For characterization of a high molecular-weight protein group prevailing in the tumor nuclear matrix, monoclonal antibodies to MAP-like protein p260 and to fibronectin were used. Immunoperoxidase reaction in Western blots of nuclear matrix electrophoregrams revealed protein p260 both in normal liver and hepatomas 27 and 22a while fibronectin was found in hepatomas, but absent in the normal liver. Immunoelectron microscopy with gold-conjugated antibodies showed p260 to be uniformly spread in the nuclei while fibronectin was localized mostly at the periphery of the tumour nuclei.

[Characteristics of protein metabolism in labyrinthine tissue].

The synthesis of total protein in organic culture of the internal ear was studied in 16-day embryo of CBA mice exposed to altering factors. The experiments showed feasibility of partial recovery for impaired metabolic processes in the labyrinth following phonophoretic introduction of mitochondrial coenzymes and inhibitors of lysosomal activity. Formation of systemic structural trace by modelling of acoustic stress and verification of protein stress agents was tested making it possible to identify an important component in dysadaption mechanism in mature CBA mice labyrinth.

[Effects of gamma irradiation on biosynthesis of nuclear matrix proteins of the liver in pregnant rats and their embryos].

A study was made of the incorporation of 35S-methionine into nuclear matrix proteins of hepatic cells of pregnant rats and their embryos subjected to single gamma-irradiation (60Co, 1 and 2 Gy, 0.0233 Gy/s) on days 3, 13 and 17 of pregnancy and embryogenesis. On day 21 of pregnancy and embryogenesis a decrease in the rate of incorporation of 35S-methionine into nuclear matrix proteins was shown to be a function of radiation dose and time of pregnancy and embryogenesis on the moment of exposure.

[The effect of gamma irradiation on the structure and enzymatic activity of the nuclear membrane of the liver in pregnant rats and their embryos].

Morphological and biochemical investigations of pregnant rats and embryo liver cell nuclei after in vivo irradiation in the doses of 1 and 2 Gr revealed their high radiosensitivity at all stages of gestation and embryonal development. At damaging effect of radiation, we managed to observe sharp accumulation of products of lipid peroxide oxidation and suppression of the activities of such enzymes as cytochrome-c-oxidase, NAD.N-cytochrome-c-reductase, ATPase and RNAase in liver nuclei of pregnant rats and embryos.

[Protein kinase activity of proteins extracted by triton X-100 from isolated rat liver cell nuclei and Zajdela hepatoma].

Proteins extracted with Triton X-100 from rat liver tissue and Zajdela hepatoma nuclei exhibited similar electrophoretic properties of both proteins and phosphoproteins if they were separated by means of electrofocusing. Four protein-kinase activity peaks were detected in each of these preparations. Three protein-kinases from rat liver tissue and Zajdela hepatoma were similar in their electrofocusing point and substrate specificity.

[Proteolytic degradation of nuclear matrix proteins in the rat liver, Zajdela's hepatoma and hepatoma 22A in the presence of ATP].

An intense proteolytic degradation of both proteins and phosphoproteins has been observed in isolated nuclear matrices from rat liver, Zajdela Hepatoma and Hepatoma 22a, incubated with NP-40, DTT and gamma-[32P] ATP being most intense in Hepatoma 22a. Practically all phosphoproteins of Hepatoma 22a nuclear matrix degraded. This implies either an extremely high proteolytic activity in the preparation or the presence of a specific to phosphoproteins protease absent from rat liver and Zajdela Hepatoma nuclear matrices.

[Skeletal structures of the cell nucleus in the normal state and pathology].

The structure and composition of the nuclear skeleton (nuclear matrix) are considered. The literature data are referred to and the findings of the original author's research on the associations of the nuclear matrix with DNA, its involvement in the control of replication and transcription occurring on the nuclear matrix sites. Special attention is given to the protein composition of the nuclear matrix, and to its changes in tumour growth, virus infection, as well as during mitosis and embryonal development.

[Effect of actinomycin D, cycloheximide, puromycin and mitomycin C on the biosynthesis of heat shock proteins in the nuclear matrix of Chinese hamster fibroblasts].

The thermal shock proteins with molecular mass of 86 kD and pI 5.5 as well as of 70 kD and pI 5.2-5.

[Heat-shock proteins in the nuclear matrix of Chinese hamster fibroblasts].

Heating of Chinese hamster fibroblasts (46 degrees C, 10 min) results in sharp inhibition of protein biosynthesis in the homogenate, nuclei and, in a lesser degree, in the nuclear matrix. The ratio of specific radioactivity of nuclear matrix 35S-proteins to the homogenate radioactivity taken for 100% increases after the heat shock 2,5-fold. Thus, protein biosynthesis in the nuclear matrix is more stable to the damaging action of heat shock than that in the homogenate and nuclei.

[Effect of hyperthermia on the polypeptide composition of the nuclear matrix of the rat liver].

The increase in rat body temperature by 2-3 degrees as a result of overheating (45 degrees C, 22% humidity) over 90 and 120 min is accompanied by changes in the rate of labeled precursors incorporation into rat liver protein fractions. The incorporation of labeled amino acids into liver nuclear matrix proteins within the first 90 min of overheating is somewhat decreased, whereas 120 min thereafter it exceeds by 30% the corresponding values in control animals kept at room temperature. The polypeptide pattern of the nuclear matrix in hyperthermia is characterized by an increased relative content of polypeptide components around Mr 100, 55, 40 and 30 kDa against a decreased level of several polypeptides as compared to the control.

[Phosphorylation of the nuclear matrix proteins of the liver and of Zajdela's hepatoma in the rat].

The rate of protein phosphorylation in isolated nuclear matrices from liver and Zajdela's hepatoma is very high, being even slightly higher than in isolated nuclei. This indicates that active protein kinases remain tightly bound to the nuclear matrix, since the areas of phosphorylation are the same. However, during isolation of the nuclear matrix from labeled nuclei in the absence of proteolysis and dephosphorylation inhibitors, most part of the label is eliminated from nuclear matrix proteins.

[Inhibition by antibiotics of the incorporation of labelled amino acids into the nuclear matrix proteins of the Zajdela hepatoma].

The incorporation of radioactivity into nuclear matrix proteins during incubation of Zajdela hepatoma cells with labelled amino acids was strongly inhibited by chloramphenicol and cycloheximide and slightly inhibited by actinomycin D and mitomycin C. The antibiotics studied inhibited the incorporation of the radioactive label preferentially into proteins with Mr 150 000-220 000, approximately 55 000 and less than 26 000. During incubation of ascites tumour cells with antibiotics, predominantly with chloramphenicol, a decrease in the content of some protein components was observed as well.

[Selective inhibition by chloramphenicol of protein biosynthesis in ascites tumor cells].

Chloramphenicol in a dose of 50-200 micrograms/ml sharply inhibits the incorporation of 14C-labelled amino acids into proteins of ascites Zajdela hepatoma cells while it has no effect on protein biosynthesis in rat liver cells. In vivo chloramphenicol selectively inhibits this process in ascites tumour cells of rat Zajdela hepatoma and mouse Ehrlich carcinoma and hepatoma 22a, without inhibiting the process in various organs of tumour-bearing animals. The inhibition of labelled amino acid incorporation into nuclear and especially nuclear matrix proteins is more pronounced than into the whole tissue.

[Carbohydrate components of the nuclear matrix in rat liver and hepatoma].

The Con A-peroxidase reaction has demonstrated glycoproteins with molecular masses of 200 and 50 kilodalton on the polyacrylamide gel-SDS electrophoregrams of the molecular matrices isolated from rat liver, hepatoma 27 and Zajdela's ascites hepatoma. Both hepatomas contained an additional band of about 38 kilodalton, whereas Zajdela's hepatoma distinct bands of 54 kilodalton and less demonstrable of over 200 and about 105 and 68 kilodalton. Electron microscopy showed Con A-ferritin staining, more prominent in hepatomas than in the liver, at the periphery of isolated nuclear matrix preparations.

[Peculiarities of protein composition of nuclear matrix in some tumors and cultures of embryonic fibroblasts of the Chinese hamster].

The polypeptide pattern of the nuclear matrix of hepatomas differs significantly from that of intact liver. On the contrary, the polypeptide pattern of the nuclear matrix of Chinese hamster fibroblast culture is similar to that of tumour cells. In our studies the nuclear matrix was characterized by an increased content of polypeptides with Mr = 120,000-135,000 and 150,000-200,000 and a protein group with Mr of about 13,000 and lower.