scholarly journals The organizational fate of intermediate filament networks in two epithelial cell types during mitosis.

1985 ◽  
Vol 100 (1) ◽  
pp. 93-102 ◽  
Author(s):  
J C Jones ◽  
A E Goldman ◽  
H Y Yang ◽  
R D Goldman
Keyword(s):  
Electron Microscopy ◽  
Epithelial Cell ◽  
Nuclear Envelope ◽  
Hela Cells ◽  
Close Association ◽  
Cell Types ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Mitotic Apparatus ◽  
Mouse Keratinocytes

Intermediate filaments (IF) appear to be attached to the nuclear envelope in various mammalian cell types. The nucleus of mouse keratinocytes is enveloped by a cagelike network of keratin-containing bundles of IF (IFB). This network appears to be continuous with the cytoplasmic IFB system that extends to the cell surface. Electron microscopy reveals that the IFB appear to terminate at the level of the nuclear envelope, frequently in association with nuclear pore complexes (Jones, J. C .R., A. E. Goldman, P. Steinert, S. Yuspa, and R. D. Goldman, 1982, Cell Motility, 2:197-213). Based on these observations of nuclear-IF associations, it is of interest to determine the fate and organizational states of IF during mitosis, a period in the cell cycle when the nuclear envelope disassembles. Immunofluorescence microscopy using a monoclonal keratin antibody and electron microscopy of thin and thick sections of mitotic mouse keratinocytes revealed that the IFB system remained intact as the cells entered mitosis and surrounded the developing mitotic spindle. IFB were close to chromosomes and often associated with chromosome arms. In contrast, in HeLa, a human epithelial cell, keratin-containing IFB appear to dissemble as cells enter mitosis (Franke, W. W., E. Schmid, C. Grund, and B. Geiger, 1982, Cell, 30:103-113). The keratin IFB in mitotic HeLa cells appeared to form amorphous nonfilamentous bodies as determined by electron microscopy. However, in HeLa, another IF system composed primarily of a 55,000-mol-wt protein (frequently termed vimentin) appears to remain morphologically intact throughout mitosis in close association with the mitotic apparatus (Celis, J.E., P.M. Larsen, S.J. Fey, and A. Celis, 1983, J. Cell Biol., 97:1429-34). We propose that the mitotic apparatus in both mouse epidermal cells and in HeLa cells is supported and centered within the cell by IFB networks.

scholarly journals High resolution scanning electron microscopy of the nuclear envelope: demonstration of a new, regular, fibrous lattice attached to the baskets of the nucleoplasmic face of the nuclear pores.

1992 ◽  
Vol 119 (6) ◽  
pp. 1429-1440 ◽  
Author(s):  
M W Goldberg ◽  
T D Allen
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Resolution ◽  
Nuclear Envelope ◽  
Nuclear Lamina ◽  
Objective Lens ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Triturus Cristatus ◽  
Scanning Electron

The nuclear envelope (NE) of amphibian oocytes can be readily isolated in relatively structurally intact and pure form and has been used extensively for structural studies. Using high resolution scanning electron microscopy (HRSEM), both surfaces of the NE can be visualized in detail. Here, we demonstrate the use of HRSEM to obtain high resolution information of NE structure, confirming previous data and providing some new information. NEs, manually isolated from Triturus cristatus oocytes, have been mounted on conductive silicon chips, fixed, critical point dried and coated with a thin, continuous film of chromium or tantalum and viewed at relatively high accelerating voltage in a field emission scanning electron microscope with the sample within the objective lens. Both nucleoplasmic and cytoplasmic surfaces of the nuclear pore complexes (NPC) have been visualized, revealing the cytoplasmic coaxial ring, associated particles, central plug/transporter and spokes. The nucleoplasmic face is dominated by the previously described basketlike structure attached to the nucleoplasmic coaxial ring. In Triturus, a novel, highly regular flat sheet of fibers, termed the NE lattice (NEL) has been observed attached to the distal ring of the NPC basket. The NEL appears to be distinct from the nuclear lamina. Evidence for the NEL is also presented in thin TEM sections from Triturus oocytes and GVs and in spread NEs from Xenopus. A model is presented for NEL structure and its interaction with the NPCs is discussed.

scholarly journals Interphase Nuclei of Many Mammalian Cell Types Contain Deep, Dynamic, Tubular Membrane-bound Invaginations of the Nuclear Envelope

1997 ◽  
Vol 136 (3) ◽  
pp. 531-544 ◽  
Author(s):  
Mark Fricker ◽  
Michael Hollinshead ◽  
Nick White ◽  
David Vaux
Keyword(s):  
Nuclear Envelope ◽  
Time Lapse ◽  
Cell Types ◽  
Live Cells ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Nuclear Surface ◽  
Topological Features ◽  
Cytoplasmic Transport ◽  
Pore Complexes

The nuclear envelope consists of a doublemembraned extension of the rough endoplasmic reticulum. In this report we describe long, dynamic tubular channels, derived from the nuclear envelope, that extend deep into the nucleoplasm. These channels show cell-type specific morphologies ranging from single short stubs to multiple, complex, branched structures. Some channels transect the nucleus entirely, opening at two separate points on the nuclear surface, while others terminate at or close to nucleoli. These channels are distinct from other topological features of the nuclear envelope, such as lobes or folds. The channel wall consists of two membranes continuous with the nuclear envelope, studded with features indistinguishable from nuclear pore complexes, and decorated on the nucleoplasmic surface with lamins. The enclosed core is continuous with the cytoplasm, and the lumenal space between the membranes contains soluble ER-resident proteins (protein disulphide isomerase and glucose-6-phosphatase). Nuclear channels are also found in live cells labeled with the lipophilic dye DiOC6. Time-lapse imaging of DiOC6-labeled cells shows that the channels undergo changes in morphology and spatial distribution within the interphase nucleus on a timescale of minutes. The presence of a cytoplasmic core and nuclear pore complexes in the channel walls suggests a possible role for these structures in nucleo–cytoplasmic transport. The clear association of a subset of these structures with nucleoli would also be consistent with such a transport role.

Persistence of major nuclear envelope antigens in an envelope-like structure during mitosis in Drosophila melanogaster embryos

1989 ◽  
Vol 94 (3) ◽  
pp. 463-470 ◽  
Author(s):  
A. Harel ◽  
E. Zlotkin ◽  
S. Nainudel-Epszteyn ◽  
N. Feinstein ◽  
P.A. Fisher ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Early Embryo ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Interphase Nuclei ◽  
Mitotic Apparatus ◽  
Morphological Studies ◽  
Indirect Immunofluorescence Microscopy ◽  
Early Embryos ◽  
Pore Complexes

Using monoclonal antibodies, we followed the fate of three different nuclear envelope proteins during mitosis in Drosophila early embryos by indirect immunofluorescence microscopy. Two of these proteins, lamin and otefin, a newly characterized nuclear envelope polypeptide with an apparent Mr of 53,000, are apparently present in an envelope-like structure that is present throughout mitosis. Immunoelectron microscopy of interphase nuclei indicates that otefin, like lamin, is not a component of nuclear pore complexes. In contrast with lamin and otefin, gp188, a putative pore complex component, was completely redistributed through the surrounding cytoplasm during prophase in comparable early embryo specimens and was present in an envelope only in interphase. Together with previous morphological studies by other workers, these data suggest that the entire mitotic apparatus including condensed chromosomes and spindle is enclosed by an envelope throughout mitosis during early embryogenesis in Drosophila. This ‘spindle envelope’, as it has been named by others, contains both lamin and otefin but probably not pore complex proteins.

scholarly journals Identification of new transmembrane proteins concentrated at the nuclear envelope using organellar proteomics of mesenchymal cells

2018 ◽  
Author(s):  
Li-Chun Cheng ◽  
Sabyasachi Baboo ◽  
Cory Lindsay ◽  
Liza Brusman ◽  
Salvador Martinez-Bartolomé ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Nuclear Membrane ◽  
Nuclear Periphery ◽  
Transmembrane Proteins ◽  
Nuclear Lamina ◽  
Cell Types ◽  
Nucleocytoplasmic Transport ◽  
Membrane Dynamics ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes

AbstractThe nuclear envelope (NE) is an endoplasmic reticulum (ER) subdomain that contains characteristic components dedicated to nuclear functions. These include nuclear pore complexes (NPCs) – the channels for nucleocytoplasmic transport, and the nuclear lamina (NL) – a scaffold for NE and chromatin organization at the nuclear periphery. Since numerous human diseases associated with NE/NL proteins occur in mesenchyme-derived cells, a more comprehensive characterization of proteins concentrated at the NE in these cell types is warranted. Accordingly, we used proteomics to analyze NE and other subcellular fractions isolated from mesenchymal stem cells and from differentiated adipocytes and myocytes. We evaluated the proteomics datasets to calculate relative protein enrichment in the NE fraction, using a spectral abundance-based scoring system that accurately described most benchmark proteins. We then examined five high-scoring transmembrane proteins expressed in all three cell types that were not previously known to be enriched at the NE. Using quantitative immunofluorescence microscopy to track ectopically expressed proteins, we validated that all five of these components are substantially concentrated at the NE of multiple cell types. One (Itprip) is exposed to the outer nuclear membrane, a second (Smpd4) is enriched at the NPC, and the three others (Mfsd10, Tmx4, and Arl6ip6) are suggested to reside in the inner nuclear membrane. Considering their sequences and other features, these proteins provide new focal points for studying the functions and membrane dynamics of the NE. Our datasets should be useful for identifying additional NE-concentrated proteins, and for evaluating candidates that are identified in screening.

scholarly journals Lamins position the nuclear pores and centrosomes by modulating dynein

2015 ◽  
Vol 26 (19) ◽  
pp. 3379-3389 ◽  
Author(s):  
Yuxuan Guo ◽  
Yixian Zheng
Keyword(s):  
Nuclear Envelope ◽  
Neural Progenitor Cells ◽  
Cell Types ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Intermediate Filament Proteins ◽  
Centrosome Separation ◽  
Pore Complexes ◽  
Type V

Lamins, the type V nuclear intermediate filament proteins, are reported to function in both interphase and mitosis. For example, lamin deletion in various cell types can lead to an uneven distribution of the nuclear pore complexes (NPCs) in the interphase nuclear envelope, whereas deletion of B-type lamins results in spindle orientation defects in mitotic neural progenitor cells. How lamins regulate these functions is unknown. Using mouse cells deleted of different combinations or all lamins, we show that lamins are required to prevent the aggregation of NPCs in the nuclear envelope near centrosomes in late G2 and prophase. This asymmetric NPC distribution in the absence of lamins is caused by dynein forces acting on NPCs via the dynein adaptor BICD2. We further show that asymmetric NPC distribution upon lamin depletion disrupts the distribution of BICD2 and p150 dynactin on the nuclear envelope at prophase, which results in inefficient dynein-driven centrosome separation during prophase. Therefore lamins regulate microtubule-based motor forces in vivo to ensure proper NPC distribution in interphase and centrosome separation in the mitotic prophase.

Nuclear Envelope Dynamics During Mitosis

1988 ◽  
Vol 46 ◽  
pp. 224-225
Author(s):  
Brian Burke
Keyword(s):  
Nuclear Envelope ◽  
Membrane Vesicles ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Animal Cells ◽  
Interphase Chromosome ◽  
Lamin B ◽  
Chromosome Architecture ◽  
Complex Membrane ◽  
Pore Complexes

The nuclear envelope is a complex membrane structure that forms the boundary of the nuclear compartment in eukaryotes. It regulates the passage of macromolecules between the two compartments and may be important for organizing interphase chromosome architecture. In interphase animal cells it forms a remarkably stable structure consisting of a double membrane ouerlying a protein meshwork or lamina and penetrated by nuclear pore complexes. The latter form the channels for nucleocytoplasmic exchange of macromolecules, At the onset of mitosis, however, it rapidly disassembles, the membranes fragment to yield small vesicles and the lamina, which is composed of predominantly three polypeptides, lamins R, B and C (MW approx. 74, 68 and 65 kDa respectiuely), breaks down. Lamins B and C are dispersed as monomers throughout the mitotic cytoplasm, while lamin B remains associated with the nuclear membrane vesicles.

scholarly journals Correlation between structure and mass distribution of the nuclear pore complex and of distinct pore complex components.

1990 ◽  
Vol 110 (4) ◽  
pp. 883-894 ◽  
Author(s):  
R Reichelt ◽  
A Holzenburg ◽  
E L Buhle ◽  
M Jarnik ◽  
A Engel ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Nuclear Envelope ◽  
Three Dimensional ◽  
Structural Features ◽  
Nuclear Pore ◽  
Xenopus Laevis Oocyte ◽  
Three Dimensional Model ◽  
Transmission Electron ◽  
Freeze Dried

Nuclear pore complexes (NPCs) prepared from Xenopus laevis oocyte nuclear envelopes were studied in "intact" form (i.e., unexposed to detergent) and after detergent treatment by a combination of conventional transmission electron microscopy (CTEM) and quantitative scanning transmission electron microscopy (STEM). In correlation-averaged CTEM pictures of negatively stained intact NPCs and of distinct NPC components (i.e., "rings," "spoke" complexes, and "plug-spoke" complexes), several fine structural features arranged with octagonal symmetry about a central axis could reproducibly be identified. STEM micrographs of unstained/freeze-dried intact NPCs as well as of their components yielded comparable but less distinct features. Mass determination by STEM revealed the following molecular masses: intact NPC with plug, 124 +/- 11 MD; intact NPC without plug, 112 +/- 11 MD; heavy ring, 32 +/- 5 MD; light ring, 21 +/- 4 MD; plug-spoke complex, 66 +/- 8 MD; and spoke complex, 52 +/- 3 MD. Based on these combined CTEM and STEM data, a three-dimensional model of the NPC exhibiting eightfold centrosymmetry about an axis perpendicular to the plane of the nuclear envelope but asymmetric along this axis is proposed. This structural polarity of the NPC across the nuclear envelope is in accord with its well-documented functional polarity facilitating mediated nucleocytoplasmic exchange of molecules and particles.

scholarly journals The Three Fungal Transmembrane Nuclear Pore Complex Proteins of Aspergillus nidulans Are Dispensable in the Presence of an Intact An-Nup84-120 Complex

2009 ◽  
Vol 20 (2) ◽  
pp. 616-630 ◽  
Author(s):  
Hui-Lin Liu ◽  
Colin P.C. De Souza ◽  
Aysha H. Osmani ◽  
Stephen A. Osmani
Keyword(s):  
High Temperature ◽  
Nuclear Envelope ◽  
Aspergillus Nidulans ◽  
Nuclear Pore Complex ◽  
Mitotic Spindle ◽  
Spindle Pole ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Spindle Pole Bodies ◽  
Pore Complexes

In Aspergillus nidulans nuclear pore complexes (NPCs) undergo partial mitotic disassembly such that 12 NPC proteins (Nups) form a core structure anchored across the nuclear envelope (NE). To investigate how the NPC core is maintained, we affinity purified the major core An-Nup84-120 complex and identified two new fungal Nups, An-Nup37 and An-ELYS, previously thought to be vertebrate specific. During mitosis the An-Nup84-120 complex locates to the NE and spindle pole bodies but, unlike vertebrate cells, does not concentrate at kinetochores. We find that mutants lacking individual An-Nup84-120 components are sensitive to the membrane destabilizer benzyl alcohol (BA) and high temperature. Although such mutants display no defects in mitotic spindle formation, they undergo mitotic specific disassembly of the NPC core and transient aggregation of the mitotic NE, suggesting the An-Nup84-120 complex might function with membrane. Supporting this, we show cells devoid of all known fungal transmembrane Nups (An-Ndc1, An-Pom152, and An-Pom34) are viable but that An-ndc1 deletion combined with deletion of individual An-Nup84-120 components is either lethal or causes sensitivity to treatments expected to destabilize membrane. Therefore, the An-Nup84-120 complex performs roles, perhaps at the NPC membrane as proposed previously, that become essential without the An-Ndc1 transmembrane Nup.

scholarly journals Cytochemical studies on the relation of nucleoside triphosphatase activity to ribonucleoproteins in isolated rat liver nuclei.

1980 ◽  
Vol 28 (1) ◽  
pp. 27-35 ◽  
Author(s):  
A Vorbrodt ◽  
G G Maul
Keyword(s):  
Nuclear Envelope ◽  
Rat Liver ◽  
Enzyme Reaction ◽  
Point Of View ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Isolated Rat Liver ◽  
Rat Liver Nuclei ◽  
Liver Nuclei ◽  
Isolated Rat

Cytochemical tests for nucleosidetriphosphatase (NTPase) and Bernhard's preferential staining for ribonucleoproteins (RNP) were applied to isolated rat liver nuclei. The strongest and most easily reproducible positive reaction for NTPase was detected at pH 7.7 with ATP and GTP. This reaction was activated by Mg2+ and Ca2+ and inhibited by Be2+, Zn2+, quercetin, and ribonuclease. The major sites of enzyme reaction were intranuclear RNA-containing structures. Incubation of nuclei in ATP-stimulated RNA-release medium eliminated a considerable part of the material showing both NTPase reaction and staining for RNP; the perichromatin granules disappeared, while interchromatin granules remained. NTPase activity in the nuclear envelope seems to be associated with the annular part of nuclear pore complexes (permanent component) and with RNP particles translocated through nuclear pores or attached to the surface of nuclei (transitional component). From a morphological point of view, these observations support previous biochemical data suggesting the existence of a connection between NTPase activity and the translocation of RNP particles through the nuclear envelope.

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