Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Nuclear Matrix”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 307 records · Page 17Linked to original sources
PubMed1998

Similarity between nuclear matrix proteins of various cells revealed by an improved isolation method.

Comparative analysis of nuclear matrix proteins by two-dimensional electrophoresis may be greatly impaired by copurifying cytoskeletal proteins. The present data show that the bulk of adhering cytofilaments may mechanically be removed by shearing of nuclei pretreated with vanadyl ribonucleoside complexes. Potential mechanisms of action not based on ribonuclease inhibition are discussed. To individually preserve the integrity of nuclear structures, we developed protocols for the preparation of nuclear matrices from three categories of cells, namely leukocytes, cultured cells, and tissue cells. As exemplified with material from human lymphocytes, cultured amniotic cells, and liver tissue cells, the resulting patterns of nuclear matrix proteins appeared quite similar. Approximately 300 spots were shared among the cell types. Forty-nine of these were identified, 21 comprising heterogeneous nuclear ribonucleoproteins. Heterogeneous nuclear ribonucleoproteins L and nuclear lamin B2 isoforms were identified by amino acid sequencing and mass spectrometry. However, individually expressed proteins, such as the proliferating cell nuclear antigen, also pertained following application of the protocols. Thus, enhanced resolution and comparability of proteins improve systematic analyses of nuclear matrix proteins from various cellular sources.

Amniotic Fluid↗
PubMed2003

Nuclear matrix localization of high mobility group protein I(Y) in a transgenic mouse model for prostate cancer.

Nuclear shape and the underlying nuclear structure, the nuclear matrix in cancer cells. Since the NM composition is considered to maintain nuclear shape and architecture, nuclear matrix proteins (NMPs) may be involved in transformation. Our laboratory has recently characterized a subset of NMPs that are associated with prostate cancer development in the transgenic adenocarcinoma of mouse prostate (TRAMP) model. One of the identified NMPs, E3E, has a similar molecular weight (22 kDa) with a protein known as HMGI(Y). HMGI(Y) belongs to a group of non-histone and chromatin-associated proteins, high-mobility-group (HMG) proteins, and it has been shown to associate with the NM. HMGI(Y) has been reported to be elevated in different types of cancer including prostate cancer. In this study, we examined the expression of HMGI(Y) protein in the NMP composition of the TRAMP model during the progression from normal to neoplasia. The expression of HMGI(Y) in the NMP extracts of three prostatic epithelial cell lines derived from a 32-week TRAMP mouse: TRAMP-C1, TRAMP-C2, and TRAMP-C3 was also examined. Using both one-dimensional and high-resolution two-dimensional immunoblot analyses, we found that: (i) HMGI(Y) is a nuclear matrix protein expressed as two protein bands with MW of 22-24 kDa and (ii) HMGI(Y) expression is correlated with neoplastic and malignant properties in late stage TRAMP prostate tumors. Overall, these findings support the evidence that HMGI(Y) can be utilized as a marker and prognostic tool for prostate cancer.

Adenocarcinoma↗
PubMed1999

Biochemical and morphological changes in the nuclear matrix prepared from apoptotic HL-60 cells: effect of different stabilizing procedures.

Apoptotic cell death is characterized by deep morphological changes that take place in the nucleus. It is unclear whether modifications also occur in the nuclear matrix, a mainly proteinaceous structure that conceivably acts as a nuclear framework. We have investigated whether biochemical and morphological alterations of the nuclear matrix prepared from apoptotic HL-60 cells were dependent on the manipulations to which isolated nuclei were subjected before DNase I digestion and 2 M NaCl extraction. Our results showed that the stabilizing procedures employed to preserve the inner fibrogranular network and nucleolar remnants of the matrix (i.e., a 37 degrees C incubation; exposure to sodium tetrathionate at 4 degrees C; exposure to sodium tetrathionate at 37 degrees C) had no effect on the protein recovery of apoptotic nuclear matrices, which was always approximately two- to fivefold less than in control matrices. Moreover, one- and two-dimensional gel analysis of nuclear matrix proteins showed that, in apoptotic samples, striking quantitative changes were present, as compared with controls. Once again, these changes were seen irrespective of the stabilizing procedures employed. Also, transmission electron microscope analysis showed similar morphological alterations in all types of apoptotic nuclear matrices. By contrast, the immunofluorescent distribution of the 240-kDa NuMA protein seen in apoptotic samples was more sensitive to the stabilizing treatments. Our results indicate that the biochemical and morphological changes of the apoptotic nuclear matrix are largely independent of the isolation protocols and strengthen the contention that destruction of the nuclear matrix network is one of the key events leading to apoptotic nuclear destruction.

Apoptosis↗
PubMed1991

Synthesis and phosphorylation of nuclear matrix proteins following a toxic dose of retinoic acid in cycling and differentiating HL-60 cells.

Exposure of HL-60 cells to 2 microM retinoic acid, twice the dose necessary for differentiation, initiated protein synthesis within 2 h exposure in the nuclear matrix proteins and phosphorylation of a subfraction of these proteins, designated the phenol-soluble nuclear proteins. These processes were examined by fluorography of two-dimensional polyacrylamide gels. Three cell-cycle related stress proteins (22, 70c, 70x Mr x 10(-3)), were seen in the nuclear matrix fraction that were synthesized early and disappeared rapidly following dosing with retinoic acid. In control cells, protein 120 was also cell-cycle related and showed modest synthesis in nuclear matrix and strong phosphorylation in phenol-soluble fraction. Within 5 h after dosing, p120 exhibited alteration in phosphorylation as evidenced by mapping of [32P]-labeled peptides. Two nuclear matrix proteins, p52 and p55, incorporated [3H] retinoic acid rapidly, were cell-cycle-related, and disappeared within 12 h of dosing. Progressive increases in the labeling of the nuclear matrix and phenol-soluble nuclear proteins with increasing retinoic acid exposure was apparent in G2-phase at 96 h time-after-dosing.

Antigens, Nuclear↗
PubMed1984

Evidence for attachment of interphase chromatin to the nuclear matrix via matrix-bound nucleosomes.

Chromatin structure has been studied in the sites of attachment to the nuclear matrix in interphase mouse liver and spleen nuclei. The patterns of fragmentation of the DNA belonging to these sites (0.3-2% of total DNA in spleen and liver, respectively) with staphylococcal nuclease and DNAase I were very close to those of usual nucleosomal chains. Moreover, the nuclear matrix preparations contained all five major histones, including H1, in almost stoichiometric amounts. The histone/DNA ratios for the matrix were also similar to those found in nuclei. These findings and the size of the matrix-protected DNA indicated that interphase chromatin was attached to the nuclear matrix via matrix-bound nucleosomes and, to a much lesser extent, oligonucleosomes up to 5-6 units long. Two-dimensional electrophoretic separation of the matrix-bound histones revealed that modifications of histone H1 and, probably, of other histones were distinguished from those in bulk chromatin. Study of binding of exogenously added labeled histone octamers or mononucleosomal size DNA to nuclear matrix excluded the possibility of their artifactual trapping during the isolation procedure.

Animals↗
PubMed1992

Human telomeres are attached to the nuclear matrix.

This report shows that human telomeres are tightly associated with the nuclear matrix. Telomere attachment is observed in several cell types and in all stages of interphase. Mapping experiments show that telomeres are anchored via their TTAGGG repeats; a subtelomeric repeat located immediately proximal to the telomeric TTAGGG repeats is quantitatively released from the nuclear matrix by restriction endonuclease cleavage. TTAGGG repeats introduced at chromosome-internal sites by DNA transfection do not behave as matrix attached loci, suggesting that the telomeric position of the repeats is required for their interaction with the nuclear matrix. These findings are consistent with the idea that telomeres function as a nucleoprotein complex.

Base Sequence↗
PubMed1995

The tissue-specific nuclear matrix protein, NMP-2, is a member of the AML/CBF/PEBP2/runt domain transcription factor family: interactions with the osteocalcin gene promoter.

The nuclear matrix protein, NMP-2, was originally identified as an osteoblast-specific DNA-binding complex localized exclusively to the nuclear matrix. NMP-2 was shown to recognize two binding sites, site A (nt-605 to -599) and site B (nt -441 to -435), in the rat bone-specific osteocalcin gene promoter. This study shows that the NMP-2 binding sites A and B as well as a third NMP-2 binding site (nt -135 to -130) constitute a consensus sequence, ATGCTGGT, and represent an AML-1 recognition motif. AML-1 is a member of the AML transcription factor family which is associated with acute myelogenous leukemia and binds to the sequence TGCTGGT via its DNA-binding runt domain. Electrophoretic mobility shift assays reveal that a component of NMP-2 is a member of the AML/PEBP2/runt domain transcription factor family based on cross-competition with AML-1 consensus oligonucleotide. Limited immunoreactivity of NMP-2 with a polyclonal N-terminal AML-1 antibody and inability of the AML-1 partner protein CBF-beta to form complexes with NMP-2 indicate that NMP-2 is not identical to AML-1 but represents a variant AML/PEBP2/runt domain protein. Western and Northern blots reveal the presence of multiple AML-related proteins and AML-1 transcripts in several osseous cell lines. Furthermore, our results indicate that AML family members may selectively partition between nuclear matrix and nonmatrix compartments. Because proteins that contain a runt domain are implicated in tissue-specific transcriptional regulation, our results support the concept that the nuclear matrix mediates osteoblast-specific expression of the osteocalcin gene.

Animals↗
PubMed1990

[The anchoring of newly synthesized adenovirus DNA to the nuclear matrix].

After adenovirus infected HeLa cells were pulse labeled and pulse-chase labeled with 3H-thymidine, the nuclear matrix and DNA remaining tightly bound to the matrix were obtained by sequential cell fractionation. Measuring the radioactivity of labeled DNA indicated that newly synthesized viral DNA specifically attach to the nuclear matrix and the amount of binding DNA is in direct proportion to the viral DNA replication activity: then the DNA gradually detach from the matrix and are involved in viral assembly. Electron microscopic autoradiography of the extracted cells showed the virion and viral DNA associated with the nuclear matrix, and thus further confirmed the anchoring of newly synthesized viral DNA to the nuclear matrix.

Adenoviruses, Human↗
PubMed1987

Specific interaction of simian virus 40 large T antigen with cellular chromatin and nuclear matrix during the course of infection.

We analyzed the subnuclear distribution of the simian virus 40 (SV40) large tumor (large T) antigen during the course of viral infection. Three distinct nuclear subclasses were detected in SV40 lytically infected TC7 cells (large T antigen in the nucleoplasm, at the cellular chromatin, and at the nuclear matrix). During the course of infection the relative subnuclear distribution of large T antigen changed significantly at about the switch from the early to late phase of infection: at early times postinfection, large T antigen was present mainly in the nucleoplasm and at the cellular chromatin, and nuclear-matrix-associated large T antigen was barely detectable. Concomitant with the onset of viral DNA replication, the amount of nuclear-matrix-associated large T antigen increased drastically. During the further course of infection large T antigen accumulated at the cellular chromatin and nuclear matrix, paralleling the increase in viral DNA synthesis. The biological significance of this correlation was corroborated by analysis of cells infected with the SV40 mutant tsA58 at permissive (32 degrees C) and restrictive (39 degrees C) temperatures. tsA58 large T antigen failed to initiate viral DNA replication in infected cells kept at the restrictive temperature and also failed to associate with the cellular chromatin and nuclear matrix. By blocking viral DNA synthesis with aphidicolin, an inhibitor of DNA polymerase alpha, we were able to show that the accumulation of large T antigen at these structures does not result from the binding of large T antigen to viral chromatin but reflects an association with cellular components of the chromatin and nuclear matrix of infected cells.

Animals↗
PubMed1987

[Electron microscopic characteristics and polypeptide composition of the nuclear matrix of liver cells in mice with autoimmune disease].

A study was made of the ultrastructure and polypeptide composition of liver cell nuclear matrix of F1NZB/NZW hybrid mice imitating human systemic Lupus erythematosus. Electron microscopy reveals enlargement in fibrous lamina diameter and increase in pore complex density up to the age of 8-9 months. In the terminal stages of the disease (12-13 months of age) a gradual attenuation of the intranuclear matrix and disappearance of pore complexes is observed along with a segregation and subsequent fragmentation of residual nucleoli which results eventually in the general degradation of the nuclear matrix. 30-35 polypeptide bands with molecular weight from 200 to 10 kD are revealed in polyacrylamide gel electrophoresis of the liver cell nuclear matrix of hybrid mice. Several protein bands in the high molecular weight region of 200-150 kD are strongly enhanced, and a triplet with molecular weight 70-60 kD is distinctly visible. The results obtained are interpreted as an indication of a protecting cellular reaction against antinuclear autoantibodies in the earlier stages, and a degradation of the nuclear matrix in terminal stages of the disease. It is supposed that the electron microscopic and electrophoretic patterns of the nuclear matrix indicate an accumulation of collagenous proteins.

Animals↗
PubMed1991

Regulation of transcription-factor activity during growth and differentiation: involvement of the nuclear matrix in concentration and localization of promoter binding proteins.

Several lines of evidence are presented which support involvement of the nuclear matrix in regulating the transcription of two genes, histone and osteocalcin, that are reciprocally expressed during development of the osteoblast phenotype. In the 5' regulatory region of an H4 histone gene, which is expressed in proliferating osteoblasts early during the developmental/differentiation sequence, a dual role is proposed for the nuclear matrix binding domain designated NMP-1 (-589 to -730 upstream from the transcription start site). In addition to functioning as a nuclear matrix attachment site, the sequences contribute to the upregulation of histone gene transcription, potentially facilitated by concentration and localization of an 84kD ATF DNA binding protein. A homologous nuclear matrix binding domain was identified in the promoter of the osteocalcin gene, which is expressed in mature osteoblasts in an extracellular matrix undergoing mineralization. The NMP binding domain in the osteocalcin gene promoter resides contiguous to the vitamin D responsive element. Together with gene and transcription factor localization, a model is proposed whereby nuclear matrix-associated structural constraints on conformation of the osteocalcin gene promoter facilitates vitamin D responsiveness mediated by cooperativity at multiple regulatory elements.

Animals↗
PubMed1994

[Enzymatic activity of the nuclear matrix].

The scope of the review is to illustrate the great diversity of enzymatic activities bound to the nuclear matrix. These data are usually summarized in terms of replication, transcription, DNA repair, etc. Such an approach is understandable; however, the great diversity of enzymes is thereby obscured. The review presents the data on enzymatic activities according to the International Enzyme Classification (EC) with the main emphasis on the enzymological aspects of the phenomena described. The enzymes represent almost all classes of enzymes discovered in the nuclear matrix: oxidoreductases, transferases, hydrolases, isomerases and ligases. The presence of ligases is supposed. Nuclear matrix enzymes form functional systems which provide the replication, transcription and regulation of gene expression, DNA repair, transduction of signals by the secondary messengers, antiviral defence, maintenance and modification of the nuclear matrix structure and recombination.

DNA Repair↗
PubMedDate not supplied

Rat seminal-vesicle secretory protein SVS II binds DNA with a preference for the 5' regulatory region of secretory protein SVS IV gene: co-isolation with components of the nuclear matrix.

In rats, the ventral prostate and seminal vesicles produce distinct sets of proteins whose functions and tissue-specific regulation by androgens remain unclear. We have utilized the genes encoding the major secretory protein of seminal vesicles, SVS IV, and the C3 subunit of prostatein of the ventral prostate to study how the nuclear matrix might determine their tissue-specific gene expression. Nuclear matrix proteins were prepared from purified nuclei with DNase and 2 M NaCl, separated in SDS gels, and transferred onto membranes for DNA-binding (southwestern) and immunological (western) analyses. The 5' region of the SVS IV gene (SVS IV-7S) bound to a 45,000-kDa molecular-weight protein band in the nuclear matrix of seminal vesicles but not to that of ventral prostate, kidney, or liver. Sequencing revealed that this band was a seminal-vesicle secretory protein, SVS II, whose identity was confirmed with an anti-SVS II antiserum in western blots. Actin-like protein, similar in mobility to SVS II, was detected in seminal-vesicle and ventral prostate nuclear matrix, but not in seminal-vesicle fluid. Reducing agent (10 mM dithiothreitol) and acidic (pH 6.5) buffer did not eliminate SVS II, but isolation of nuclear matrices with ammonium sulfate, nucleases, and urea decreased SVS II immunoreactivity and removed actin-like protein. SVS II binding to SVS IV-7S DNA was greater than its binding to either a comparable fragment of the C3 gene or linearized pUC-19 plasmid, and it was not eliminated by a 100-fold competition. When seminal-vesicle fluid was mixed with rat liver, some SVS II co-isolated with the nuclear-matrix proteins, indicating that nonspecific interactions contribute to its association with the nucleoskeleton. However, these interactions may not represent the intracellular behavior of SVS II in seminal-vesicle epithelium. Sequence comparisons indicate significant homologies between SVS II and some other seminal proteins, including bovine caltrin, which, under the name seminalplasmin, is known to possess antimicrobial activity. Collectively, these data suggest that in addition to its known functions, SVS II may also bind extraneous DNA in seminal fluid. Additionally, SVS II may participate as a structural component in the organization of a tissue-specific seminal-vesicle nuclear matrix.

Animals↗
PubMed1983

Nuclear matrix and hnRNP share a common structural constituent associated with premessenger RNA.

Nuclear matrix and heterogeneous nuclear ribonucleoprotein (hnRNP) were compared to establish whether premessenger RNA (premRNA) was associated with a same constituent in both structures. The isolation of nuclear matrix included the removal of chromatin and of 0.4 M KCl-soluble material. HnRNP, isolated by a standard method was also treated by 0.4 M KCl. Both isolation procedures caused the removal of DNA, histones, a fraction of small nuclear RNA and of nonhistone proteins including the hnRNP proteins in the 30 000-40 000 mol. wt. range. High resolution autoradiography showed that hnRNA remained associated with the residual fibrils in both structures. They both contained the same premRNA and maturation products as shown by the analysis of the transcripts of the early region 3 of adenovirus 2. In addition, the small nuclear RNA and protein of the salt-resistant complexes were also present in the matrix. The results are compatible with the idea that the salt-resistant complexes from hnRNP constitute the fibrils associated with premRNA in the nucleoplasmic matrix. The fibrils may be the basic unit of splicing and their organization in matrix might provide the spatial configuration necessary for regulation.

Cell Nucleus↗
PubMed2004

Breakpoint cluster regions of the AML-1 and ETO genes contain MAR elements and are preferentially associated with the nuclear matrix in proliferating HEL cells.

The spatial organization in interphase nuclei of the breakpoint cluster regions (BCRs) of the AML-1 and ETO genes frequently participating in reciprocal t(8;21) translocations was studied using cytological and biochemical approaches. Both BCRs were found to be localized preferentially, but not exclusively, to the nuclear matrix, as shown by hybridization of specific probes with nuclear halos. This association was not related to transcription, because the transcribed regions of both genes located far from BCRs were located preferentially in loop DNA, as shown by in situ hybridization. The sites of association with the nuclear matrix of the intensely transcribed AML-1 gene were mapped also using the biochemical PCR-based approach. Only the BCR was found to be associated with the nuclear matrix, whereas the other transcribed regions of this gene turned out to be positioned randomly in respect to the nuclear matrix. The data are discussed in the framework of the hypothesis postulating that the nuclear matrix plays an important role in determining the positions of recombination-prone areas.

Cell Proliferation↗
PubMed1995

The channels model of nuclear matrix structure.

The specificity of eukaryotic DNA organization into loops fixed to the nuclear matrix/chromosomal scaffold has been studied for more than fifteen years. The results and conclusions of different authors remain, however, controversial. Recently, we have elaborated a new approach to the study of chromosomal DNA loops. Instead of characterizing loop basements (nuclear matrix DNA), we have concentrated our efforts on the characterization of individual loops after their excision by DNA topoisomerase II-mediated DNA cleavage at matrix attachment sites. In this review the results of applying this mapping approach are compared with the results and conclusions from studies of nuclear matrix DNA. An attempt is also made to reconsider all data about the specificity of DNA interactions with the nuclear matrix and to suggest a model of spatial organization of the eukaryotic genome which resolves apparent contradictions between these data.

Animals↗
PubMed1993

Identification of proteins immunologically related to vertebrate lamins in the nuclear matrix of the myxomycete Physarum polycephalum.

Lamin-like proteins have been identified as components of the nuclear matrix of the myxomycete Physarum polycephalum. A 67 kDa homologue was detected by immunoblotting of nuclear matrix proteins with affinity-purified anti-lamin antibodies of human autoimmune sera. A 65 kDa lamin B homologue was identified with polyclonal antibodies against turkey erythrocyte lamin B in nuclei and nuclear matrix of Physarum amoebae and plasmodia. Indirect immunofluorescence microscopy revealed that the 65 and 67 kDa proteins are localized in the nuclear lamina of plasmodial nuclei.

Animals↗
PubMed1996

Flow cytometric analysis of nuclear matrix proteins: method and potential applications.

The nuclear matrix (NM) is an important structural component of the nucleus that participates in the regulation of several diverse metabolic processes. Immunometric assays have shown that alterations in NM-associated functions and morphological characteristics may occur as a result of changes in NM composition. Recent evidence suggests that detection of quantitative or qualitative changes in nuclear matrix protein (NMP) composition may be useful in the diagnosis of cancer and as a reliable indicator of cell death. We have developed an in situ flow cytometric technique for the simultaneous detection of specific NMPs and DNA content in fixed, permeabilized cells. Illustrative results from two different applications of these methods involving two different cell lines (human melanoma and promyelocytic leukemia) are presented, including: 1) measurements of NM breakdown in necrotic and apoptotic cells after treatment with the cytotoxic agents camptothecin, etoposide, or hyperthermia; and 2) detection of changes in NMP content immediately after heat shock. We demonstrate that the technique is useful for the identification of cell-cycle specificity of NM breakdown and allows correlations to be made between the kinetics of DNA fragmentation and NMP solubilization. Furthermore, our studies indicate that flow cytometric detection of changes in NM composition may be useful for identifying different modes and temporal patterns of cell death. We discuss other potential applications of the technique and advantages over standard biochemical assays.

Antibodies, Monoclonal↗