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Biomedical subjects

E S Vasetskiĭ

Publications and source records attributed to E S Vasetskiĭ.

16 recordsLinked to original sources
PubMed1990

[Nuclear protein factors binding with specific DNA sequences].

Primary structure of thousands of genes is being determined in many laboratories worldwide. While it is relatively easy to analyse the coding region(s) of genes, it is usually hard to understand what is located in non-coding regions. A non-coding region may contain very valuable information about the mode of functioning of a given gene, e. g. promoters, enhancers, silencers etc. The regulatory function of these sequences is determined by their interaction with certain sequence-specific proteins, i. e. the presence of a certain DNA sequence in a non-coding region of a gene may suggest that the gene is regulated by a specific protein factor. This minireview summarizes recent data on most known eukaryotic sequence-specific DNA-binding protein factors, including their origin, DNA consensus, and their role in expression of corresponding genes.

Animals↗
PubMedDate not supplied

[Changes in chromatin organization during early development and carcinogenesis].

Similar changes in chromatin organization take place during development and carcinogenesis. The size of chromatin loop domains fixed on the nuclear skeleton (matrix) increased from 20 to approximately 200 kbp. These changes are accompanied by an increased size of replicons and altered specificity of loop attachment to the nuclear matrix. During carcinogenesis, inverse changes in the chromatin structure are observed, neoplastic cells are dedifferentiated and return to the initial state. In this review, we consider new experimental data on organization of the DFNA loops and nuclear matrix in embryogenesis and carcinogenesis.

Animals↗
PubMedDate not supplied

[Attachment of DNA loops to an artificial matrix does not affect the origin of replication initiation in early development of African clawed frog].

Replication initiation proceeds in a random fashion in early development of Xenopus laevis. The replication origins become fixed only at later stages of development after the mid-blastula transition. Specification of replication origins occurs at the same time with the specification of the DNA attachment to the nuclear matrix. Replication origins of many species coincide or are located in the vicinity of sites of DNA attachment to the nuclear matrix. The present work was dedicated to development of an experimental system where DNA loops were specifically attached to an artificial matrix and a study of an effect of this attachment on specificity of DNA replication initiation in extracts of Xenopus laevis oocytes. We have found that DNA attachment to the artificial matrix increases the efficacy of DNA replication as compared to the control, but does not affect the replication specificity. It is likely that the transition from non-specific to specific replication is determined by a combination of several factors, and specificity of DNA attachment to a matrix alone is not sufficient for specification of a replication origin.

Animals↗
PubMedDate not supplied

[Spatial organization of the chicken alpha-globin gene domain in cells of different].

We have developed a technique for mapping the sites of DNA attachment to the nuclear matrix by hybridization of nuclear matrix DNA with an oligonucleotide array. The latter was made by immobilization of 60-mer oligonucleotides distributed within the area under study with a 2 Kb step on nylon filter. Using this approach we have analyzed the mode of interaction of a 100 Kb fragment of chicken chromosome 16 including the alpha-globin gene domain with the nuclear matrix. The 40 Kb DNA loop including all alpha-globin genes was detected in erythroid cells. One of the borders of this loop colocalized with the previously mapped MAR element and CTCF-dependent enhancer-blocking element. Also, a long transcribed area was found to be preferentially associated with the nuclear matrix. The spatial organization of the area under study in lymphoid cells was drastically different from this observed in erythroid cells.

Animals↗
PubMedDate not supplied

[Coprecipitation of proteins and DNA-protein complexes with magnesium sarcolysate: research on an association of topoisomerase I and RNA polymerase with DNA].

A specific cosedimentation of proteins and their complexes with DNA at low temperature (M-band technique) has been demonstrated. Model experiments with reconstituted SV40 DNA-topoisomerase I and SV40 DNA-E. coli RNA polymerase complexes demonstrated the potential and capacities of the method. It allows fractionation of DNA-protein complexes from naked DNA and has greater range, higher reproducibility and lower background values than similar methods.

Bacterial Proteins↗
PubMedDate not supplied

[Topoisomerase I is connected with the regulatory zone of transcripted active mini-chromosomes of the SV40 virus].

Proteins bound to SV40 DNA in sarkosyl-treated nuclei have been studied. The major component is topoisomerase I, a 60-70 kDa protein, which possesses a strong DNA-nicking activity in the presence of detergents. An SV40 fraction containing tightly bound proteins constitutes 2-3% of the total nuclear SV40 DNA and is enriched in transcriptionally active DNA as monitored by distribution of RNase-resistant in vivo pulse labelled RNA. A small SV40 DNA fraction which is relaxed due to covalent binding of topoisomerase I upon sarkosyl treatment of isolated nuclei is also enriched in transcriptionally active DNA. In vivo topoisomerase I cleavage sites on SV40 DNA have been located by indirect end-labelling. Two preferential binding sites have been detected, both in the SV40 regulatory region.

Chromatography, Gel↗
PubMedDate not supplied

[Characteristics of DNA sequences in the sites of permanent attachment to the nuclear matrix located in the vicinity of replication initiation site].

The permanent DNA attachment sites to the nuclear matrix in the domain of chicken alpha-globin genes originally found in erythrocyte nuclei are shown to exist in sperm and cultured fibroblast cells too. Short fragments of permanently attached to the nuclear matrix DNA have been cloned and sequenced. A primary structure of a 1.7 k.b. fragment from 5'-region of chicken alpha-globin gene domain containing both replication origin and permanent attachment site has been determined. A region possessing homologies with papovaviral replication origins and putative mammalian ARS elements has been found on the 1.7 k.b. fragment. A region containing short internal repeats and GC-rich motifs has also been found. Similar motifs were observed in several of the cloned short fragments of DNA permanently attached to the nuclear matrix.

Animals↗
PubMedDate not supplied

[A large T-antigen of SV40 virus: involvement in replication of cellular DNA and interactions with nuclear proteins].

The SV40 large T-antigen is involved in transcription and replication of viral DNA and malignant cell transformation. In order to gain insight into its interaction with other proteins, we analyzed its distribution during the cell cycle using a cell-free system derived from Xenopus eggs that reproduces most nuclear events linked to the cell cycle in vitro. T-antigen associates with chromatin independently of the nuclear membrane formation. A transient association of T-antigen with the nuclear matrix is observed during ongoing DNA synthesis. However, T-antigen colocalizes neither with RPA pre-replication centers nor replication foci as detected by biotin dUTP labeling. Both intranuclear colocalization and biochemical interaction with the endogenous p53 were detected, which occurs at the nuclear matrix. These data are discussed in view of the T-antigen transforming activity.

Animals↗