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.

Assembly of nuclear pore complexes and annulate lamellae promotes normal pronuclear development in fertilized mammalian oocytes

1998 ◽  
Vol 111 (19) ◽  
pp. 2841-2854 ◽  
Author(s):  
P. Sutovsky ◽  
C. Simerly ◽  
L. Hewitson ◽  
G. Schatten
Keyword(s):  
Cell Types ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Annulate Lamellae ◽  
Oocyte Activation ◽  
Nuclear Pores ◽  
Microtubule Inhibitor ◽  
Cytoplasmic Transport ◽  
Oocyte Cytoplasm ◽  
Pore Complexes

In addition to functional nuclear pore complexes engaged in nucleo-cytoplasmic transport, the cytoplasmic stacks of pore complexes, called annulate lamellae, exist in numerous cell types. Although both annulate lamellae and nuclear pore complexes are present in fertilized mammalian oocytes, their relative roles in the process of fertilization and preimplantation development are not known. Using epifluorescence and electron microscopy, we explored their fate during bovine fertilization. The assembly of annulate lamellae in bovine oocytes was triggered by sperm-oocyte binding and continued concomitantly with the incorporation of the nuclear pores in the nuclear envelopes of the developing male and female pronuclei. This process was also induced by the parthenogenetic activation of metaphase-II-arrested oocytes. Depletion of Ca2+, previously implicated in oocyte activation and in the insertion of pore complexes into the nuclear envelope, prevented the formation of nuclear pore complexes, but not the assembly of annulate lamellae in oocyte cytoplasm. Injection of the nuclear pore antagonist, wheat germ agglutinin, into the cytoplasm of mature oocytes that were subsequently fertilized caused the arrest of pronuclear development, indicating the requirement of nuclear pore complexes for normal pronuclear development. Treatment of the fertilized oocytes with the microtubule inhibitor, nocodazole, prevented gathering of annulate lamellae around the developing pronuclei, insertion of nuclear pores into their nuclear envelopes, and further pronuclear development. The formation of the male pronuclei was reconstituted in Xenopus egg extracts and reflected the behavior of nuclear pores during natural fertilization. These data suggest that nuclear pore complexes are required for normal pronuclear development from its beginning up until pronuclear apposition. Annulate lamellae may be involved in the turnover of nuclear pore complexes during fertilization, which is in turn facilitated by the reorganization of oocyte microtubules and influx of Ca2+ into oocyte cytoplasm.

scholarly journals Cytoplasmic transport and nuclear import of plasmid DNA

2017 ◽  
Vol 37 (6) ◽  
Author(s):  
Haiqing Bai ◽  
Gillian M. Schiralli Lester ◽  
Laura C. Petishnok ◽  
David A. Dean
Keyword(s):  
Nuclear Envelope ◽  
Model Systems ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Microtubule Organizing Center ◽  
Microtubule Network ◽  
Naked Dna ◽  
Cytoplasmic Transport ◽  
Organizing Center ◽  
Pore Complexes

Productive transfection and gene transfer require not simply the entry of DNA into cells and subsequent transcription from an appropriate promoter, but also a number of intracellular events that allow the DNA to move from the extracellular surface of the cell into and through the cytoplasm, and ultimately across the nuclear envelope and into the nucleus before any transcription can initiate. Immediately upon entry into the cytoplasm, naked DNA, either delivered through physical techniques or after disassembly of DNA–carrier complexes, associates with a large number of cellular proteins that mediate subsequent interactions with the microtubule network for movement toward the microtubule organizing center and the nuclear envelope. Plasmids then enter the nucleus either upon the mitotic disassembly of the nuclear envelope or through nuclear pore complexes in the absence of cell division, using a different set of proteins. This review will discuss our current understanding of these pathways used by naked DNA during the transfection process. While much has been elucidated on these processes, much remains to be discerned, but with the development of a number of model systems and approaches, great progress is being made.

scholarly journals Active movements of the chromatoid body. A possible transport mechanism for haploid gene products.

1979 ◽  
Vol 80 (3) ◽  
pp. 621-628 ◽  
Author(s):  
M Parvinen ◽  
L M Parvinen
Keyword(s):  
Nuclear Envelope ◽  
Time Lapse ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Gene Products ◽  
Rna Transport ◽  
Chromatoid Body ◽  
Genome Analyses ◽  
Pore Complexes ◽  
Rat Spermatogenesis

Recent data indicate that the chromatoid body typical of rat spermatogenesis may contain RNA synthesized in early spermatids by the haploid genome. Analyses of living step-1 and step-3 spermatids by time-lapse cinephotomicrography have shown that the chromatoid body moves in relation to the nuclear envelope in two different ways. Predominantly in step 1, the chromatoid body moves along the nuclear envelope on a wide area surrounding the Golgi complex and has frequent transient contacts with the latter organelle. In step 3, the chromatoid body was shown to move perpendicular to the nuclear envelope. It was seen located very transiently at the top of prominent outpocketings of the nuclear envelope with apparent material continuities through nuclear pore complexes to intranuclear particles. The rapid movements of the chromatoid body are suggested to play a role in the transport of haploid gene products in the early spermatids, including probably nucleocytoplasmic RNA transport.

A biochemical and immunological comparison of nuclear and cytoplasmic pore complexes

1996 ◽  
Vol 109 (7) ◽  
pp. 1813-1824 ◽  
Author(s):  
A. Ewald ◽  
U. Kossner ◽  
U. Scheer ◽  
M.C. Dabauvalle
Keyword(s):  
Nuclear Envelope ◽  
Nuclear Pore Complex ◽  
Transport Processes ◽  
Immunogold Electron Microscopy ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Nuclear Surface ◽  
Annulate Lamellae ◽  
Binding Studies ◽  
Pore Complexes

Pore complexes are not confined to the nuclear envelope but can also be found in the cytoplasm of numerous cell types in the form of annulate lamellae (AL). We have induced formation of AL by exposure of rat cells (line RV) to sublethal doses of the antimitotic drug vinblastine sulfate, and compared the distribution of several nuclear pore complex proteins (nucleoporins) in the nuclear envelope and AL by immunocytochemistry, cytochemical lectin binding studies and immunoblot analyses of nuclear and AL-enriched fractions. All the antibodies used yielded punctate nuclear surface staining in immunofluorescence microscopy which is characteristic for nuclear pore complex components. When we applied antibodies against the nucleoporin p62, AL were visualized as numerous cytoplasmic dot-like structures. Immunogold electron microscopy confirmed the correspondence of the cytoplasmic bodies with stacks of AL. Antibodies to constituents of the cytoplasmic (nup180) and nucleoplasmic (nup153) filaments extending from both sides of nuclear pore complexes also stained the AL, indicating that pore complexes are intrinsically asymmetric assemblies independent of their specific intracellular topology. By contrast, AL were negative with five different antibodies against the transmembrane nuclear pore glycoprotein gp210 and the lectin concanavalin A (ConA) known to bind to the oligosaccharide side chains of gp210. Similarly, there was no staining of the AL with antibodies to the other nuclear pore membrane protein so far known in higher eukaryotes, POM121. Immunoblot analyses confirmed the presence of p62, nup180 and nup153 in both the nuclear and AL fractions and the absence of gp210 and POM121 from AL. Our results do not support the generally held view that gp210 and POM121 function in anchoring the pore complex scaffold to the pore membrane. Rather, they point to a role for these proteins in transport processes through the nuclear pore complexes. Since AL are not involved in nucleocytoplasmic transport processes they may lack components of the transport machinery.

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.

Quantifying tagged mRNA export flux via nuclear pore complexes in single live cells

2021 ◽  
Vol 545 ◽  
pp. 138-144
Author(s):  
Yueyue Jing ◽  
Yilin Lv ◽  
Jingya Ye ◽  
Longfang Yao ◽  
Liwen Chen ◽  
...  
Keyword(s):  
Mrna Export ◽  
Live Cells ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Export Flux ◽  
Pore Complexes

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 In Vivo Dynamics of Nuclear Pore Complexes in Yeast

1997 ◽  
Vol 136 (6) ◽  
pp. 1185-1199 ◽  
Author(s):  
Mirella Bucci ◽  
Susan R. Wente
Keyword(s):  
Nuclear Envelope ◽  
Recipient Cell ◽  
Nucleocytoplasmic Transport ◽  
Yeast Cells ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Central Location ◽  
Nuclear Membranes ◽  
Mutant Strains ◽  
Pore Complexes

While much is known about the role of nuclear pore complexes (NPCs) in nucleocytoplasmic transport, the mechanism of NPC assembly into pores formed through the double lipid bilayer of the nuclear envelope is not well defined. To investigate the dynamics of NPCs, we developed a live-cell assay in the yeast Saccharomyces cerevisiae. The nucleoporin Nup49p was fused to the green fluorescent protein (GFP) of Aequorea victoria and expressed in nup49 null haploid yeast cells. When the GFP–Nup49p donor cell was mated with a recipient cell harboring only unlabeled Nup49p, the nuclei fused as a consequence of the normal mating process. By monitoring the distribution of the GFP–Nup49p, we could assess whether NPCs were able to move from the donor section of the nuclear envelope to that of the recipient nucleus. We observed that fluorescent NPCs moved and encircled the entire nucleus within 25 min after fusion. When assays were done in mutant kar1-1 strains, where nuclear fusion does not occur, GFP–Nup49p appearance in the recipient nucleus occurred at a very slow rate, presumably due to new NPC biogenesis or to exchange of GFP– Nup49p into existing recipient NPCs. Interestingly, in a number of existing mutant strains, NPCs are clustered together at permissive growth temperatures. This has been explained with two different hypotheses: by movement of NPCs through the double nuclear membranes with subsequent clustering at a central location; or, alternatively, by assembly of all NPCs at a central location (such as the spindle pole body) with NPCs in mutant cells unable to move away from this point. Using the GFP–Nup49p system with a mutant in the NPCassociated factor Gle2p that exhibits formation of NPC clusters only at 37°C, it was possible to distinguish between these two models for NPC dynamics. GFP– Nup49p-labeled NPCs, assembled at 23°C, moved into clusters when the cells were shifted to growth at 37°C. These results indicate that NPCs can move through the double nuclear membranes and, moreover, can do so to form NPC clusters in mutant strains. Such clusters may result by releasing NPCs from a nuclear tether, or by disappearance of a protein that normally prevents pore aggregation. This system represents a novel approach for identifying regulators of NPC assembly and movement in the future.

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