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At least 127 records · Page 7Linked to original sources
PubMed1986

A domain of SV40 capsid polypeptide VP1 that specifies migration into the cell nucleus.

In order to identify the determinants responsible for the nuclear migration of simian virus 40 (SV40) polypeptide VP1, the 5'-terminal portion of the SV40 VP1 gene was fused with the complete cDNA sequence of poliovirus capsid polypeptide VP1 and the hybrid gene was inserted into an SV40 vector in place of the normal SV40 VP1 gene. Deletions of various length were generated in the SV40 VP1 portion of the hybrid gene, resulting in a set of truncated genes encoding 2-40 NH2-terminal amino acids from SV40 VP1, followed by poliovirus VP1. Monkey kidney cells were infected by the deleted hybrid viruses in the presence of an early SV40 amber mutant as helper, and the subcellular localization of the fusion proteins was determined by indirect immunofluorescence using an anti-poliovirus VP1 immune serum. The presence of the first 11 NH2-terminal amino acids from SV40 VP1 was found to be sufficient to target the fusion protein to the cell nucleus. Deletions extending from the NH2- towards the COOH-terminal end of the protein were next generated. Transport of the SV40 VP1-poliovirus VP1 fusion polypeptide to the nucleus was abolished when the first eight amino acids from SV40 VP1 were deleted. Thus the sequence of the first eight NH2-terminal amino acids of SV40 VP1 appears to contain a nuclear migration signal which is sufficient to target the protein to the cell nucleus.

Antigens, Polyomavirus Transforming↗
PubMed1992

Subthalamic nucleus cell firing in the 6-OHDA-treated rat: basal activity and response to haloperidol.

Single unit recordings from neurons of the subthalamic nucleus were made in control and 6-hydroxydopamine (6-OHDA)-treated rats anesthetized with chloral hydrate. Subthalamic nucleus cells in this preparation exhibited a wide range of firing rates and three different firing patterns. These patterns were defined as 'burst', 'normal', and 'mixed' based on comparisons of their interspike interval histograms. Four to 6 weeks after 6-OHDA treatment there was no change in the basal firing rates of subthalamic nucleus cells, but there was a significant shift in firing pattern, with a smaller proportion of cells exhibiting the 'normal' firing pattern. The response of subthalamic nucleus neurons to acute administration of haloperidol was also altered in 6-OHDA-treated rats tested 4-6 weeks post-lesion, with a significantly greater proportion of cells responding to doses of haloperidol as low as 0.2 mg/kg (i.v.) with increases in firing rate of 20% or more. These results suggest that the subthalamic nucleus is probably not involved in the increases in basal levels of dopamine cell activity observed previously in the 6-OHDA-treated rat, but may play a role in the acute induction of depolarization block of dopamine cell firing in response to haloperidol administration in this model.

Action Potentials↗
PubMed2002

Metabolic-energy-dependent movement of PML bodies within the mammalian cell nucleus.

Promyelocytic leukaemia (PML) nuclear bodies are present in most mammalian cell nuclei. PML bodies are disrupted by PML retinoic acid receptor alpha (RAR alpha) oncoproteins in acute promyelocytic leukaemia. These bodies contain numerous proteins, including Sp100, SUMO-1, HAUSP(USP7), CBP and BLM, and they have been implicated in aspects of transcriptional regulation or as nuclear storage depots. Here, we show that three classes of PML nuclear bodies can be distinguished, on the basis of their dynamic properties in living cells. One class of PML bodies is particularly noteworthy in that it moves by a metabolic-energy-dependent mechanism. This represents the first example of metabolic-energy-dependent transport of a nuclear body within the mammalian cell nucleus.

Animals↗
PubMed2005

Atelocollagen for culture of human nucleus pulposus cells forming nucleus pulposus-like tissue in vitro: influence on the proliferation and proteoglycan production of HNPSV-1 cells.

Nucleus pulposus (NP) is responsible for maintaining function and structure of the disc. Scaffolds to culture disc cells three-dimensionally are emphasized in recent reports on development of a new method for treating disc degeneration using cell transplantation and tissue engineering. Among artificial scaffolds and cell carrying materials, Atelocollagen is a collagen gel that has an advantage in safety issues over others. However, to date there has been no study that investigated culture of human nucleus pulposus cells in Atelocollagen. To investigate whether Atelocollagen could be used as a culture scaffold and if it has any effect on cell proliferation and proteoglycan (PG) production, as well as to find the optimal commercially available Atelocollagen for NP cell transplantation and tissue engineering, we cultured human NP cell line HNPSV-1, in three different Atelocollagen and compared with alginate. Furthermore, NP-like tissues were generated using these cells and different Atellocollagen solutions. Results showed that both DNA synthesis and content is significantly greater when cultured in Atelocollagen than in alginate. On the other hand, proteoglycan synthesis and accumulation was significantly greater in alginate compared with the 0.3% Atelocollagen scaffolds; with 3% Atelocollagen, however, results were similar. NP-like tissue generated by Atelocollagen showed good water and proteoglycan preservation. The current study demonstrates that the use of Atelocollagen as an in vitro culture scaffold for three-dimensional culture of human NP cell lines is indeed feasible and moreover, Atelocollagen possesses the potential to become a candidate scaffold for cell transplantation or tissue engineering for the treatment of intervertebral disc degeneration.

Adult↗
PubMed1999

Taxol affects nuclear lamina and pore complex organization and inhibits import of karyophilic proteins into the cell nucleus.

Treatment of human carcinoma cells with Taxol induces focal unraveling of the nuclear lamina and extensive clustering or ectopic localization of the nuclear pore complexes. These striking aberrations develop when the cells are transferred to drug-free medium and are allowed to complete mitosis. As could be confirmed by terminal deoxynucleotidyl transferase-mediated nick end labeling assays, 4,6-diamidino-2-phenylindole staining, 5-bromo-2-deoxyuridine incorporation, and examination of the nuclear lamins by Western blotting, the malformation of the nuclear envelope is not a consequence of apoptosis or G1 arrest. In fact, Taxol-treated cells possessing a defective nuclear envelope remain alive and replication-competent for at least 24 h, undergoing programmed death 72 h after removal of the drug. While still in the nonapoptotic state, these cells lose the ability to import karyophilic proteins into the nucleus. Diminished nucleocytoplasmic transport through the nuclear pore complex can be readily demonstrated by in vitro assays involving digitonin-permeabilized cells or in vivo monitoring of nuclear factor-kappaB translocation upon stimulation with tumor necrosis factor-alpha. These observations reveal novel cellular targets of antimicrotubule drugs and may pave the way for improved schemes of anticancer treatment.

Apoptosis↗
PubMed1990

Immunocytochemistry of the cell nucleus.

This electron microscopic review addresses in situ immunocytochemistry of the mammalian cell nucleus with special reference to the use of autoantibodies, which are the major source of antinuclear antibodies. The localization of many key nuclear antigens is documented and immunocytochemical data are related to the major functional processes of transcription and processing of RNA and to replication of DNA.

Animals↗
PubMed2002

Structural and functional compartmentalization of the cell nucleus in supraoptic neurons.

It is well-established that the neuronal cell nucleus is organized in discrete compartments involved in transcription and RNA processing. The main nuclear compartments in neurons include the chromosome territories, the nucleolus, nuclear speckles of splicing factors, Cajal bodies, and nuclear rodlets. The supraoptic nucleus (SON) neurons provide a powerful model in vivo to study the organization of these nuclear compartments in response to variations of cellular activity. The upregulation of transcription in SON neurons under chronic hyperosmolar conditions is associated with 1) nuclear and nucleolar enlargement, 2) dispersion of chromatin, 3) reduction in the size of nuclear speckles, 4) increase in the number of Cajal bodies implicated in the maturation of splicing small nuclear ribonucleoproteins, and 5) proliferation of the fibrillar centers of the nucleolus, the sites of nucleolar transcription of ribosomal genes. These changes revert after the cessation of the activation by rehydration of animals. Under conditions of neuronal stress induced by hypertonic saline injection, SON neurons exhibit an early response of downregulation of transcription. This is accompanied by chromatin condensation, redistribution of splicing factors, reduction in the number of Cajal bodies, and microsegregation of the fibrillar and granular components of the nucleolus and disruption of its fibrillar centers, all of which are associated with a transitory expression of c-Fos. These changes progressively revert and at 24 hours after the stress induction a rebound upregulation of transcription is observed. These findings illustrate the transcription-dependent organization and behavior of nuclear compartments in the neuronal model of magnocellular neurosecretory cells of the hypothalamus.

Animals↗
PubMed1993

Genetic analysis of the virD operon of Agrobacterium tumefaciens: a search for functions involved in transport of T-DNA into the plant cell nucleus and in T-DNA integration.

The transferred DNA (T-DNA) is transported from Agrobacterium tumefaciens to the nucleus and is stably integrated into the genome of many plant species. It has been proposed that the VirD2 protein, tightly attached to the T-DNA, pilots the T-DNA into the plant cell nucleus and that it is involved in integration. Using agroinfection and beta-glucuronidase expression as two different very sensitive transient assays for T-DNA transfer, together with assays for stable integration, we have shown that the C-terminal half of the VirD2 protein and the VirD3 protein are not involved in T-DNA integration. However, the bipartite nuclear localization signal, which is located within the C terminus of the VirD2 protein and which has previously been shown to be able to target a foreign protein into the plant cell nucleus, was shown to be required for efficient T-DNA transfer. virD4 mutants were shown by agroinfection to be completely inactive in T-DNA transfer.

Agrobacterium tumefaciens↗
PubMed2003

Cloning and identification of a novel human RNPC3 gene that encodes a protein with two RRM domains and is expressed in the cell nucleus.

The RNA recognition motifs (RRM) domain is one of the most common eukaryotic protein folds. Proteins containing RRM domains function in important steps of posttranscriptional regulation of gene expression and are involved in processing and transport of mRNA precursors. Here we describe the cloning and characterization of a novel human RNPC3 gene containing two RNA recognition motifs. The 1870 bp cDNA encodes a protein with 517 amino acids. It also contains two bipartite nuclear targeting sequences, which is important for nuclear targeting for proteins, especially those functioning in the cell nucleus. The GFP location of the RNPC3 gene product shows that this protein is located in the cell nucleus. RT-PCR reveals that it is abundantly expressed in kidney and pancreas.

Amino Acid Motifs↗
PubMed1998

Comparison of cellular and conventional dosimetry in assessing self-dose and cross-dose delivered to the cell nucleus by electron emissions of 99mTC, 123I, 111In, 67Ga and 201T1.

The radionuclides used in nuclear medicine imaging emit numerous mono-energetic electrons responsible for dose heterogeneity at the cellular level. S(self) the self-dose per unit cumulated activity (which results from the radionuclide located in the target cell), and S(cross) the cross-dose per unit cumulated activity (which comes from the surrounding cells) delivered to a target cell nucleus by electron emissions of technetium-99m, iodine-123, indium-111, gallium-67 and thallium-201 were computed at the cellular level. An unbounded close-packed hexagonal cell arrangement was assumed, with the same amount of radioactivity per cell. Various cell sizes and subcellular distributions of radioactivity (nucleus, cytoplasm and cell membrane) were simulated. The results were compared with those obtained using conventional dosimetry. S(self) and S(cross) values depended closely on cell dimensions. While the self-dose depended on the tracer distribution, the latter affected the cross dose by less than 5%. When the tracer was on the cell membrane, the self-dose was particularly low compared to the cross-dose, as the self-dose to cross-dose ratio was always less than 11%. In the case of cytoplasmic or cell membrane distribution of radioactivity, conventional electron dosimetry slightly overestimated the dose absorbed by the target cell nucleus (by 1.08-to 1.7-fold). In contrast, conventional dosimetry strongly underestimated the absorbed dose (1.1- to 75-fold) when the radioactivity was located in the nucleus. The discrepancies between conventional and cellular dosimetry call for calculations at the cellular level for a better understanding of the biological effects of radionuclides used in diagnostic imaging.

Algorithms↗
PubMed2006

Ethanol alters access to the cell nucleus.

Ethanol is the most frequently used drug among humans. We tested the hypothesis whether ethanol, at clinically relevant concentrations modifies, signaling across the nuclear envelope (NE). In cell nuclei isolated from Xenopus oocytes, we measured NE electrical resistance and NE macromolecule permeability 1 to 20 h after addition of ethanol (0.05 to 0.2%). Furthermore, with atomic force microscopy, nuclear pores of the NE were imaged after exposure to ethanol. We found that NE permeability decreased within hours of ethanol exposure. In parallel, nuclei swell and nuclear pores form clusters in the NE. Force measurements on individual nuclear pores indicate that pores found in clusters are stiffer than those found randomly distributed in the NE. Application of a transcription blocker (actinomycin D) or RNase treatment of isolated nuclei in vitro after ethanol exposure prevents the permeability changes. In conclusion, ethanol, at commonly used concentrations, changes NE structure by transcriptional processes in the cell nucleus. Within hours, the NE becomes less permeable for diffusible ions and macromolecules. This could explain altered signaling to and communication with the cell nucleus in the pathophysiology of alcohol abuse.

Animals↗