Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Nuclear Envelope”

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 703 records · Page 39Linked to original sources
PubMed2005

Developmental regulation of PV-1 in rat lung: association with the nuclear envelope and limited colocalization with Cav-1.

Plasmalemma vesicle protein-1 (PV-1) is a caveolae-associated protein that is enriched in lung endothelial cells. The PV-1 protein is first detected in the lung at embryonic day 12, before that of caveolin-1 (Cav-1). There is a postnatal rise in PV-1 and Cav-1 mRNA levels, reaching a peak at the time of weaning and declining to their lowest levels in the adult lung. In contrast, the PV-1 protein progressively increases during postnatal development with its highest levels in the adult lung; the Cav-1 protein remains relatively constant throughout this period. Alveolar endothelial cells express both PV-1 and Cav-1 proteins, but PV-1, unlike Cav-1, is also detectable in some bronchial epithelial cells. Endothelial cells transfected with a rat PV-1 construct show a punctate membrane distribution of PV-1, perinuclear accumulation, and an association with the nuclear envelope. In these cells, PV-1 exhibits only partial perinuclear colocalization with Cav-1 and F-actin. In summary, PV-1 is developmentally regulated in the rat lung and shows a divergent intracellular localization, with a limited caveolae/Cav-1 colocalization in cultured endothelial cells.

Aging↗
PubMed2003

The Ulp1 SUMO isopeptidase: distinct domains required for viability, nuclear envelope localization, and substrate specificity.

Protein modification by the ubiquitin-like SUMO protein contributes to many cellular regulatory mechanisms. In Saccharomyces cerevisiae, both sumoylating and desumoylating activities are essential for viability. Of its two known desumoylating enzymes, Ubl-specific protease (Ulp)1 and Ulp2/Smt4, Ulp1 is specifically required for cell cycle progression. A approximately 200-residue segment, the Ulp domain (UD), is conserved among Ulps and includes a core cysteine protease domain that is even more widespread. Here we demonstrate that the Ulp1 UD by itself can support wild-type growth rates and in vitro can cleave SUMO from substrates. However, in cells expressing only the UD of Ulp1, many SUMO conjugates accumulate to high levels, indicating that the nonessential Ulp1 NH2-terminal domain is important for activity against a substantial fraction of sumoylated targets. The NH2-terminal domain also includes sequences necessary and sufficient to concentrate Ulp1 at nuclear envelope sites. Remarkably, NH2-terminally deleted Ulp1 variants are able, unlike full-length Ulp1, to suppress defects of cells lacking the divergent Ulp2 isopeptidase. Thus, the NH2-terminal regulatory domain of Ulp1 restricts Ulp1 activity toward certain sumoylated proteins while enabling the cleavage of others. These data define key functional elements of Ulp1 and strongly suggest that subcellular localization is a physiologically significant constraint on SUMO isopeptidase specificity.

Carbon-Nitrogen Lyases↗
PubMed1992

In situ imaging of agonist-sensitive calcium pools in AR4-2J pancreatoma cells. Evidence for an agonist- and inositol 1,4,5-trisphosphate-sensitive calcium pool in or closely associated with the nuclear envelope.

The activation of phospholipase C by hormones and neurotransmitters activates a complex combination of Ca2+ release and accumulation by intracellular organelles. Previously, we demonstrated that, in some cell types, the fluorescent Ca2+ indicator, fura-2, can be loaded into intracellular, agonist-sensitive Ca2+ pools (Glennon, M. C., Bird, G. St. J., Kwan, C.-Y., and Putney, J. W., Jr. (1992) J. Biol. Chem. 267, 8230-8233). In the current study, we have attempted to exploit this phenomenon by employing digital fluorescence imaging of compartmentalized fura-2 to investigate the localization and function of the major intracellular sites of Ca2+ regulation in AR4-2J pancreatoma cells. By judicious use of a surface receptor agonist together with the Ca(2+)-ATPase inhibitor, thapsigargin, cellular regions were identified whose behavior indicates that they contain the sites of agonist- and inositol 1,4,5-trisphosphate-mediated intracellular Ca2+ release. These regions were located throughout the cell and may include the nuclear envelope. They were distinct in locus and behavior from two other regions, which counterstained with fluorescent markers for nuclei and mitochondria. Fura-2 in mitochondrial regions reported low resting levels of [Ca2+], and revealed that organelles in these regions accumulate and retain Ca2+ after agonist activation. These findings demonstrate that fluorescent Ca2+ indicators can be employed to directly monitor changes in [Ca2+] in the major Ca(2+)-regulating organelles, and provide the first in situ visualization and localization of the major sites of Ca2+ regulation in cells.

Animals↗
PubMed2005

Mouse cPLA2gamma, a novel oocyte and early embryo-abundant phospholipase A2 gamma-like protein, is targeted to the nuclear envelope during germinal vesicle breakdown.

This report documents the characterization of a novel mouse oocyte protein which was originally identified by microsequence analysis of a 67.8 kDa protein spot (pI 5.7) on a Coomassie-stained two-dimensional (2D) gel of murine egg proteins. Tandem mass spectroscopic analysis of the peptides obtained from the cored protein yielded sequences that appeared to match only ovary, egg, and preimplantation embryo cDNAs. We then cloned the novel gene by RACE-PCR, and analysis of the deduced cDNA sequence found that this maternal product was approximately 56% identical to human cytosolic phospholipase A2gamma (cPLA2gamma). Based on this sequence homology, we named the molecule mouse cytosolic phospholipase A2gamma (cPLA2gamma). As with human cPLA2gamma, mouse cPLA2gamma contains a lipase consensus sequence and lacks the calcium binding domain that is found in other PLA2 proteins. However, mouse cPLA2gamma is different from human cPLA2gamma in that mouse cPLA2gamma expression is restricted to the ovary and that the protein does not contain the myristoylation and prenylation lipid-anchoring motifs that are present in human cPLA2gamma. Within oocytes, mouse cPLA2gamma localizes mainly to the oocyte cortex and to the nucleoplasm. Interestingly, during germinal vesicle breakdown, mouse cPLA2gamma aggregates dynamically relocate from the oocyte cortex to the nuclear envelope, suggesting a possible role for this putative egg-restricted phospholipase A2gamma in membrane remodeling. Furthermore, mouse cPLA2gamma protein continues to be expressed in the embryo until the 4-8-cell stage of development, suggesting that mouse cPLA2gamma may function as a previously uncharacterized maternal effect gene.

Amino Acid Motifs↗
PubMed1997

[Chromatin structure and chromosomes on preparations of interphase nuclear derivatives after removal of nuclear envelopes. I. Method of preparation and morphology of residual nuclei in human leukocytes and intestinal epitheliocytes of Chironomus].

A method of a stage by stage dismantling of the cell nucleus by a 0.5-5 min resuspending cells in physiological media containing 0.05 and 0.5% of non-ionic detergent Triton X-100 is first described. Depending on the detergent concentration and cell incubation time a suspension was obtained consisting of either practically undamaged nuclei with removed envelopes, cytoplasm-free mitotic figures and isolated envelopes gradually spreading interphase chromatin associated with nucleoplasm proteins. The article describes a technique to make from such a suspension preparations of spread and flattened derivatives of nucleus and mitotic chromosomes to use for optical microscopic research. This method allows to reveal perichromatin components of the nucleus and mitotic chromosome to study structure of chromonemic net and nucleoli of diploid nuclei of human leucocytes and non-polytenic nuclei of chironomus epitheliocytes and the discoidal structure of polynemic (low-polytenic) chromosomes from the midgut epithelium cells of chironomus larvae. An attempt was made to use the obtained preparations of flattened unenveloped nuclei in order to distinguish between human leucocytes according to the structure of their chromonemic net and silver-stained nucleolus, and to find out the manner of impregnation of argyrophilic nucleoplasm proteins. The partially isolated chironomus polynemic chromosomes have morphological manifestations of unproportional endoreduplication, local compactization of chromomers and physical association between a nucleolus and numerous of distant chromosome loci. We failed, however, to find any homology in the band pattern of such polynemic chromosomes and polytenic chromosomes of larval salivary gland cells. Individuality of chromosomes in polynemic nuclei was not so obvious due to a developed network of intra- and interchromosomal ectopic contacts. The discussion touches upon the mechanisms of isolation of nuclear envelopes and ways to restore the original shape of the unenveloped nucleus in the used hydrodynamic system with fading detergent activity. Prospects are mapped out to use this technique in the structural studies of interphase nuclei and mitotic and polynemic chromosomes.

Animals↗
PubMed1992

Pathway of incorporation of microinjected lamin A into the nuclear envelope.

When microinjected into the cytoplasm of 3T3 cells, biotinylated human lamin A rapidly enters the nucleus and gradually becomes incorporated into the nuclear lamina region as determined by immunofluorescence. The incorporation of the microinjected material takes several hours and progresses through a series of morphologically identifiable stages. Within minutes after microinjection, lamin A is found in spots distributed throughout the nucleus, except in nucleolar regions. Over a time course of up to 6 h, these spots appear to decrease in size and number as the biotinylated lamin A becomes associated with the endogenous nuclear lamina. Eventually, the typical nuclear rim staining pattern normally revealed by immunofluorescence with nuclear lamin antibodies is seen with antibiotin. This latter rim staining property is passed on to daughter cells following mitosis. These results indicate that the microinjected biotinylated nuclear lamin A retains those properties required for its integration into the lamina, as well as those necessary for the disassembly and subsequent reassembly of the nuclear lamina during cell division. The initial rapid accumulation into foci and the subsequent slower incorporation into the nuclear lamina appear to be analogous to the stages of incorporation following the microinjection of cytoskeletal intermediate filament proteins such as vimentin and keratin (Vikstrom, K., G. G. Borisy, and R. D. Goldman. 1989. Proc. Natl. Acad. Sci. USA. 86:549-553; Miller, R. K., K. Vikstrom, and R. D. Goldman. 1991. J. Cell Biol. 113:843-855). Foci are also observed in some uninjected cells using nuclear lamin antibodies, indicating that these features are a genuine component of nuclear substructure. Evidence is presented that shows the appearance of these nuclear structures is cell cycle dependent.

3T3 Cells↗
PubMed1984

Effect of dexamethasone on nuclear envelope nucleoside triphosphatase in fibroblasts 3T3 and melanoma cells MMLI.

Glucocorticoids are known to influence DNA and RNA synthesis in skin fibroblasts. In a novel approach to study this effect, we investigated the influence of the hormone analogue dexamethasone on the activity of nuclear envelope-associated nucleoside triphosphatase (NTPase) in intact cell systems (3T3 fibroblasts and MMLI melanoma cells). The NTPase is thought to be responsible for regulation of nucleocytoplasmic transport of mRNA. [3H]Dexamethasone was found to bind to nuclear ghosts at a density comparable with that of nuclear pores in this cellular fraction. Incubation of the cells for 48 h in the presence of different concentrations of dexamethasone resulted in a marked decrease of NTPase activity. Already concentrations as low as 0.1 ng/ml (3T3) or 1 ng/ml (MMLI) reduced the NTPase activity by approximately 50%. These results suggest that nuclear envelope NTPase is a site at which glucocorticoids regulate gene expression.

Animals↗
PubMed1994

Nuclear lipid metabolism in NEST: Nuclear Envelope Signal Transduction.

There is increasing evidence that nuclear lipid metabolism in NEST is an important new component in signal transducing networks and as a result, this metabolism is beginning to attract more attention. While agonist-induced nuclear lipid metabolism adds further complexity to the ever increasing array of signal transduction components, it also provides further avenues by which nuclear activities may be regulated. Identification of the coupling mechanisms, regulation, and physiological roles of nuclear lipid metabolism represents a new and exciting area of research which will have a broad impact in our understanding of signal transduction pathways.

3T3 Cells↗
PubMed1996

Genetic analysis of macromolecular transport across the nuclear envelope.

Numerous factors that promote movement of macromolecules in and out of the nucleus have now been identified. These include both soluble cytoplasmic and nucleoplasmic proteins and proteins of the nuclear pore complex (NPC). Genetic analyses of the nuclear transport process in the model organism, the budding yeast Saccharomyces cerevisiae, have revealed remarkable conservation of all of these factors. In addition, important clues as to how these factors promote the unique bidirectional movement across the NPC have emerged from studies of yeast. We summarize the characterization and genetic interactions of the soluble transport factors and present data to illustrate how genetic experiments can be used to further define the import and export pathways.

Biological Transport, Active↗
PubMed1996

Chromosomal assignment of human nuclear envelope protein genes LMNA, LMNB1, and LBR by fluorescence in situ hybridization.

We have used fluorescence in situ hybridization to establish precise chromosomal localizations for three human genes encoding four different nuclear envelope proteins. Lamin A/C (LMN1, HGMW-approved symbol LMNA) mapped to 1q21.2-q21.3, with a most probable gene assignment to 1q21.3; lamin B receptor (LBR) was localized to 1q42.1; and lamin B1 (LMNB1) was mapped to the interface of bands 5q23.3-q31.1. Assignments were determined by direct placement of signals relative to high-resolution DAPI or G-bands. Comparison of these results of band positions predicted from fractional length measurements to signal placement indicated that more accurate predictions are made using Francke idiograms and that measurement strategy avoids variance due to polymorphic chromosome segments.

Chromosome Banding↗
PubMed1994

Expression of a nuclear envelope protein recognized by the monoclonal antibody BU31 in lung tumours: relationship to Ki-67 antigen expression.

The production of the murine monoclonal antibody BU31 is described. This antibody identifies a nuclear envelope protein which is expressed in some but not all cells, and which resembles statin, a protein reported to be expressed by non-proliferating cells. BU31 was applied onto frozen sections of a series of 78 lung tumours and the staining patterns were compared with those obtained with Ki-67. There was an inverse correlation between the proportion of tumour nuclei labelled with the two reagents (r = -0.61, 95 per cent confidence intervals -0.73 to -0.45). However, the four neuroendocrine neoplasms were BU31-negative. Squamous cell carcinomas often showed a peripheral distribution of the cells stained positively with Ki-67, whereas BU31 tended to label centrally situated cells. These observations are consistent with the concept that the antigen recognized by BU31 is expressed by non-proliferating cells in these tumours.

Adult↗