Search PubMed⌕ Search

Biomedical subjects

O I Podgornaia

Publications and source records attributed to O I Podgornaia.

At least 19 recordsLinked to original sources
PubMed2005

[Multifunctional nuclear protein NAP57 specifically interacts with dead RNA-helicase p68].

NAP57 has been found as a component of nuclear matrix protein complex with ability to specifically bind alphoid DNA. Polyclonal antibodies against NAP57 were raised in order to investigate intranuclear localization and interactions of the protein. Two types of localization were observed: a) nucleoplasmic and b) nucleolar. A bulk of nucleoplasmic fraction is present in splicing factors compartments (SFC). The type of localization pattern does not depend on the cell cycle phase, but we revealed changes in NAP57 localization pattern during S phase. According to immunoprecipitation and immunofluorescence assays, NAP57 specifically interacts with DEAD RNA helicase p68 in vitro and co-localizes with helicase p68 in the nucleus of cultured cells. We suppose participation of both proteins in processing of small nuclear RNA on the SFC periphery, and positioning of the nucleolus according to centromere regions of chromosomes.

Animals↗
PubMed2004

[Larval cells of sponge Halisarca dujardini (Demospongiae, Halisarcida). I. Separation of the cells and their aggregation properties].

The majority of Demospongia members have a parenchymula larva, whose inner cells are similar to definite sponge cells. There are some contradictory opinions about the structure of larva in the marine sponge Halisarca dujardini: some authors deny the presence of inner cells, while other investigators consider this larva as a real parenchymula. We defined the larval cell types by cell separation in the percoll gradient and analysed their morphology and behaviour. The results showed the existence of 6 cell types in the parenchymula larva of H. dujardini, including 2 types of external flagellated cells. Each cell category differs in its morphology and aggregation ability.

Animals↗
PubMed2004

[Larval cells of sponge Halisarca dujardini (Demospongiae, Halisarcida). II. Some cell types marked by polyclonal antibodies].

The recent morphological and experimental data concerning the involvement of flagellated cells in sponge larvae are contradictory and testify to or against the germinal layers inversion. A study of morphogenetic processes in sponges, in particular larval metamorphosis, is complicated by difficulties in identification and succession of certain cell types. It is possible to trace the destiny of flagellated and other larval cells by marking them with antibodies (AB) specified for each cell type. We separated larval and adult sponge cells of Halisarca dujardini in percoll density gradient and obtained polyclonal AB for the majority of these cell types. The protein pattern of larval flagellated cells differed significantly from that of other cell types. The major proteins of flagellated, collencyte-like and spherulous cells were used to raise the corresponding AB. Immunoblot showed all AB to be specific for certain proteins and suitable for immunofluorescence. The AB for flagellated cells reacted with the apical cytoplasm, but not with the flagellum, the AB for major protein of collencyte-like cells stained cytoplasm granules. The AB for spherulous cells of the adult sponge reacted with larval spherulous cells supposed to be of maternal origin. So, the method of cell marking with specific polyclonal AB can facilitate analysis of the layers inversion problem, as well as elucidate the degree of cell differentiation in larvae, their conformity to cells of the adult sponge or their provisional destiny.

Animals↗
PubMed2003

[The mammalian centromere organization].

Routine and recently obtained data on the pattern and functions of the mammalian centromeres and kinetochores have been reviewed. Several problems of kinetochore formation (centromere recognition, anaphase checkpoint) are specially discussed, in addition to the role played by centromere DNA in the interphase nucleus consideration.

Anaphase↗
PubMed2002

[Protein composition of mesoglea and mesogloeal cells of medusa Aurelia aurita].

Protein composition of mesoglea of the scyphomedusa Aurelia aurita was revealed in SDS-PAGE. Some major bands are visible in mesoglea of a mature medusa: 30, 45-47, 85 kDa, three bands between 100-200 kDa, and several bands with molecular weights > 300 kDa. Polyclonal antisera RA45/47 against protein 45 kDa were raised. RA45/47 react with 45-47 kDa protein in mesogleal sample and protein 120 kDa in mesogleal cells on immunoblot. Immunohistochemical analysis of A. aurita histological sections of young and mature medusae showed antigen localization in mesogleal cell granules and in the apical part of ectodermal cells. In mature medusae, the antigen was localized also in elastic fibers. We can conclude that in A. aurita mesogleal cells, along with ectodermal cells, take part in the formation of extracellular matrix of mesoglea.

Animals↗
PubMed2001

[The murine nuclear matrix protein specificcaly binds to centromeric satellite DNA].

The nuclear matrix (NM) of mouse contains a protein (miSat BP) that can specifically bind to mouse centromeric minor satellite DNA as shown by gel shift assay. The ion-exchange chromatography on DEAE-Sepharose was used as the first miSat BP purification. MiSat BT was eluted by 0.2 M NaCl. Antibodies against p70, a human NM protein of 70 kDa described earlier as a protein recognizing human alphoid DNA, produce hypershift effect when added to the retardation incubation mix. Immunoblotting of NM and an active NM fraction (0.2 M NaCl) with these antibodies revealed a protein with 70 kDa in both preparations. This antigen retained in NM in situ being associated with residual DNA as shown by indirect immunofluorescent staining. In the untreated interphase nucleus most of miSat BP granules were shown to be colocalized with prekinetochores. We suggest that miSat BP is capable of recognizing the minor satellite DNA due to its structural features, but it does not belong to a group of constitutive centromeric proteins.

Animals↗
PubMed2001

[Localization of proteins, specifically binding highly-repetitive sequences of DNA in human spermatozoids].

Immunoblot revealed in spermatozoa alpha-satellite (sat) DNA-specific centromere protein B (CENP-B) and p70 (Enukashvily et al., 2000), a membrane telomere binding protein (MTBP/TRF2) (Podgornaya et al., 2000), and Alu-binding protein p68 (Lukyanov et al., 2000). The localization of some of these proteins in spermatozoa was defined using indirect immunofluorescence. Spermatozoa were fixed in methanol/acetic acid 3:1, or prior to fixation were treated with 5 mM heparin and 10 mM DTT. The heparin/DTT treatment causes the nuclear membrane destruction and a partial chromatin decondensation. In non-treated spermatozoa fluorescent signals from all ABs are registered near the membrane, with MTBP/TRF2 being localized closer to the acrosome than sat-DNA-specific proteins. In the treated spermatozoa MTBP/TRF2 was partially lost, whereas part of CENP-B and sat-p70 remained in contact with membrane. Another part of sat-binding proteins reveals a dot-like staining pattern, with dots confined to the DAPI-stained chromatin area, inside a nuclei. This is in partial agreement with the pattern of telomere and CEN position revealed by FISH. Commonly MTBP has a near membrane localization, being lost when the nuclear membrane is destroyed. Centromere-binding proteins are arranged in the order from the nuclear membrane towards the nuclear center, with CENP-B being situated more peripherally but not in the middle of the nucleus. This discrepancy may be explained by the fact, that some proteins are not associated with the appropriate sequences in a spermatozoon. Possibly, such a distribution of proteins may reflect their role in unpacking the paternal genetic material in a zygote.

Autoantigens↗
PubMed2000

[The Chi-like sites free minisatellite insertion in plasmids of pSV2neo family directs conversion of reporter neo gene in LM cell line].

Minisatellite loci show variability in copy number of repeat units probably due to their recombinogenic activity. In the presence of minisatellites with Chi-similar sites in plasmids the enhanced frequency of homologous recombination of defective plasmids copies of selectable gene was shown. In this work we have estimated recombinogenic activity of minisatellite DNAs without Chi-similar sites. The restoration frequency of a neo gene and the ratio of restored and not restored copies of this gene in genomic DNA of transformed clones was quantitatively estimated. We conclude that the presence of minisatellite insertion without Chi-similar sites stimulates events of gene conversion in adjacent DNA of plasmids. Plasmids with minisatellites act as acceptors of genetic information.

Animals↗
PubMed1999

[Role of nuclear matrix proteins in the formation of heterochromatin].

Heterochromatin consists mainly of satellite DNAs (stDNA), the most rapidly evolving type of DNA sequences of the eucaryotic genome. On the other hand, stDNA is involved in the formation of the functionally conserved centromere structure. Centromeres and pericentromeric stDNA, are known to be in association with nuclear matrix or chromosome scaffold at all stages of the cell cycle. Several lines of evidence show that attachment of stDNA to the nuclear matrix is specific. The first defined parts of the genes found in association with nuclear matrix/scaffold, MAR/SAR, possess some common features with the stDNA. A number of different mechanisms have previously been implicated in heterochromatin formation and centromere conservation. The role of nuclear matrix proteins, which are able to recognize common structural features of MAR/SAR and stDNA, in constitutive heterochromatin organization is discussed in the current review.

Antigens, Nuclear↗
PubMed1999

[Differentiation of osteogenic cells in culture].

The regulatory factors and cell responses during osteogenic differentiation have been reviewed. Evidence has been provided on hormone and mechanical regulation and on the extracellular matrix (ECM). The data on responses of primary cell culture and constant cell lines of osteogenic origin to these regulations are represented in the number of tables. It looks likely that the relationship with the ECM may mediate the rest of regulations, and therefore the most attention was paid to the cell-ECM interactions and, namely, to collagen-integrin interplay. A comparison of the reviewed data leads to an assumption that the ECM influence is passed through integrin receptors to the nuclear matrix connected transcriptional factors causing the next step of osteogenic differentiation.

Animals↗
PubMed1999

[Theory of integrating cellular tension and consequences from it].

Tensegrity model and implications from it have been reviewed. Experimental data confirming the model are shown. While signal vectorization is well confirmed and well depicted by the model, the vectorization of expression implied by the model has not yet been elaborated. Molecular mechanisms of functional connection between the nuclear matrix and the cytoskeleton need further observations.

Cytoskeleton↗
PubMed1998

[Mutation process in mini-satellites].

Minisatellites are tandemly repeated DNA sequences with repeat units in the range 6-100 bp. They are preferentially located in subtelomeric euchromatin of chromosomes of higher eukaryotes. Minisatellite loci frequently show variability in allele length. This variability is a consequence of high frequency of mutations which change repeat copy number of locus. The most part of minisatellite mutations are germline specific and possibly meiotic. Examples of different mutations and involved genomic mechanisms are reviewed in this paper. A possible biological role of minisatellites is discussed.

Chromosome Mapping↗
PubMed1998

[Two proteins from the nuclear matrix bind osteopontin gene promoter].

DNA transcription and replication are organized by the nuclear matrix. It has been recently shown that the osteocalcin gene promoter binds specifically two proteins, NMP-1 and NMP-2 (nuclear matrix proteins 1 and 2), from cell line ROS 17/2.8 (Bidwell et al., 1993). Osteocalcin in one of the proteins taking part in extracellular matrix mineralization during osteogenic differentiation. Osteopontin gene is also active at the late stages of osteogenesis, so we supposed that its promoter could be bound to the nuclear matrix as well. Among the nuclear matrix proteins of ROS 17/2.8 we have found a protein factor which binds the promoter region of the osteopontin gene specifically with the help of gel shift assay. Two proteins with isoelectric points of pH > 8.0 and mol. masses of 38 and 43 kDa, respectively, have been purified by affinity chromatography with the promoter region of osteopontin attached to cellulose. The mol. masses of the revealed proteins are similar to those of already characterized NMP-2 (38 kDa) and one of subunits of heterodimer NMP-1 (43 kDa). Computer analysis shows that the binding sites for these proteins exist in the osteopontin gene promoter region. So, it is very likely that we dealt with the same proteins. A further investigation could lead to characterization of a group of nuclear matrix attached osteogenic-specific transcriptional factors.

Animals↗
PubMed1997

[The collagen-binding membrane proteins of connective-tissue cells].

The pattern of cell membrane collagen-binding proteins was analysed by affinity chromatography with collagen types I, III and IV columns. We have found that connective tissue cells have three polypeptides which are able to recognize the types of collagen. These proteins have molecular weights 130, 190, and 250 kDa (reduced) according to SDS-PAGE. Proteins with M. W. 130 and 250 kDa show high affinity to collagen type III and IV, but not to collagen type I. Protein with M. W. 190 kDa binds collagen type I only. The distribution of these proteins between cells from various tissues strongly correlates with the set of collagen types interacting with cells in the intact tissue.

Animals↗
PubMed1988

[Presence in human lymphocytes of a protein specifically binding to a cloned fragment of human satellite DNA III].

PHA-stimulated human lymphocytes contain the protein (SBP) which has selectivity in binding of 1.8 kb fragment of human satellite DNA III (HS3) as compared to other DNA sequences. It is shown that the binding site is localized within 1kb Sau3A-EcoR I fragment of HS3. SBP-binding activity is increased after treatment of cells with tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA). The essential increase in a number of metaphases with chromosome endoreduplications in TPA-treated lymphocytes indicates that SBP may be involved in initiation of chromosome replication or in alteration of the mitotic spindle function.

Cloning, Molecular↗
PubMed1986

[Heterogeneity of nuclear proteins from HeLa cells specifically binding to the Alu sequence].

Nuclear proteins from HeLa cells specifically binding to the Alu-repeat cloned in the plasmid Blur8 have been studied. 0.35 M nuclear extract proteins have been separated on DEAE-cellulose. The presence of DNA-binding proteins has been found in all fractions by the technique of DNA-binding on nitrocellulose filters. The labelled restricted DNA of the plasmid Blur8 was incubated with the proteins of different fractions with the subsequent identification of specific Alu-protein complexes in polyacrylamide gel at low ionic strength. At least two proteins have been found to have the different affinity to Alu-repeat. Various functions of Alu-repeats and the possibility of their participation in the initiation of DNA replication are discussed.

DNA↗
PubMed1985

[Genetic transformation of somatic cells. II. An analysis of the status of the plasmid nucleotide sequences in chromosomal DNA and the thymidine kinase activity in transformant clone cells].

Chinese hamster A238 TK- -cells were transformed with plasmids (derivatives of pBR325) containing thymidine kinase (TK) gene of Herpes simplex virus type 1 (HSV1). The results of dot- and blot-hybridization indicate the presence of pBR325 sequences in the chromosomal fractions of DNA in the transformant clones. These sequences are probably tandemly arranged, and each cluster contains 25--50 copies. SV40 sequences cloned in pBR325 were introduced into the Chinese hamster cells by co-transformation with TK-gene of HSV1-containing plasmid DNA, and all the co-transformant clones selected for TK+-phenotype were shown by hydridization to contain 3V40 DNA fragments. Isoelectrofocusing in polyacrylamide gel shows that thymidine kinase from TK+-transformant clones is of viral type (isoelectric point 7), in contrast to the cellular enzyme (coded by chromosomal gene) having alkaline isoelectric point (pH 9). The results suggest that the true TK+-transformant cells are selected by the procedure used in this study.

Animals↗