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.

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.

scholarly journals Caenorhabditis elegans Nucleoporins Nup93 and Nup205 Determine the Limit of Nuclear Pore Complex Size Exclusion In Vivo

2003 ◽  
Vol 14 (12) ◽  
pp. 5104-5115 ◽  
Author(s):  
Vincent Galy ◽  
Iain W. Mattaj ◽  
Peter Askjaer
Keyword(s):  
Caenorhabditis Elegans ◽  
Nuclear Envelope ◽  
Protein Import ◽  
Chromatin Condensation ◽  
Size Exclusion ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
C Elegans ◽  
Pore Complexes

Nuclear pore complexes (NPCs) span the nuclear envelope and mediate communication between the nucleus and the cytoplasm. To obtain insight into the structure and function of NPCs of multicellular organisms, we have initiated an extensive analysis of Caenorhabditis elegans nucleoporins. Of 20 assigned C. elegans nucleoporin genes, 17 were found to be essential for embryonic development either alone or in combination. In several cases, depletion of nucleoporins by RNAi caused severe defects in nuclear appearance. More specifically, the C. elegans homologs of vertebrate Nup93 and Nup205 were each found to be required for normal NPC distribution in the nuclear envelope in vivo. Depletion of Nup93 or Nup205 caused a failure in nuclear exclusion of nonnuclear macromolecules of ∼70 kDa without preventing active nuclear protein import or the assembly of the nuclear envelope. The defects in NPC exclusion were accompanied by abnormal chromatin condensation and early embryonic arrest. Thus, the contribution to NPC structure of Nup93 and Nup205 is essential for establishment of normal NPC function and for cell viability.

Nuclear envelope disorganization in fibroblasts from lipodystrophic patients with heterozygous R482Q/W mutations in the lamin A/C gene

2001 ◽  
Vol 114 (24) ◽  
pp. 4459-4468 ◽  
Author(s):  
Corinne Vigouroux ◽  
Martine Auclair ◽  
Emmanuelle Dubosclard ◽  
Marcel Pouchelet ◽  
Jacqueline Capeau ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Primary Cultures ◽  
Ectopic Expression ◽  
Nuclear Pore ◽  
Lamin A ◽  
Nuclear Pore Complexes ◽  
Intermediate Filament Proteins ◽  
Partial Lipodystrophy ◽  
Nuclear Alterations ◽  
Pore Complexes

Dunnigan-type familial partial lipodystrophy (FPLD), characterized by an abnormal body fat redistribution with insulin resistance, is caused by missense heterozygous mutations in A-type lamins (lamins A and C). A- and B-type lamins are ubiquitous intermediate filament proteins that polymerize at the inner face of the nuclear envelope. We have analyzed primary cultures of skin fibroblasts from three patients harboring R482Q or R482W mutations. These cells were euploid and able to cycle and divide. A subpopulation of these cells had abnormal blebbing nuclei with A-type lamins forming a peripheral meshwork, which was frequently disorganized. Inner nuclear membrane protein emerin, an A-type lamin-binding protein, strictly colocalized with this abnormal meshwork. Cells from lipodystrophic patients often had other nuclear envelope defects, mainly consisting of nuclear envelope herniations that were deficient in B-type lamins, nuclear pore complexes, lamina-associated protein 2 beta, and chromatin. The mechanical properties of nuclear envelopes were altered, as judged from the extensive deformations observed in nuclei from heat-shocked cells, and from the low stringency of extraction of their components. These structural nuclear alterations were caused by the lamins A/C mutations, as the same changes were introduced in human control fibroblasts by ectopic expression of R482W mutated lamin A.

scholarly journals Nuclear pore complexes: dynamics in unexpected places

2001 ◽  
Vol 154 (1) ◽  
pp. 17-20 ◽  
Author(s):  
Susan K. Lyman ◽  
Larry Gerace
Keyword(s):  
Nuclear Envelope ◽  
Nuclear Pore Complex ◽  
Mammalian Cells ◽  
In Vivo Studies ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Pore Complexes ◽  
New Evidence

In vivo studies on the dynamics of the nuclear pore complex (NPC) in yeast suggested that NPCs are highly mobile in the nuclear envelope. However, new evidence indicates that in mammalian cells NPCs are stably attached to a flexible lamina framework, but a peripheral component can exchange rapidly with an intranuclear pool.

scholarly journals Nup53 Is Required for Nuclear Envelope and Nuclear Pore Complex Assembly

2008 ◽  
Vol 19 (4) ◽  
pp. 1753-1762 ◽  
Author(s):  
Lisa A. Hawryluk-Gara ◽  
Melpomeni Platani ◽  
Rachel Santarella ◽  
Richard W. Wozniak ◽  
Iain W. Mattaj
Keyword(s):  
Nuclear Envelope ◽  
Critical Role ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Egg Extracts ◽  
Multiple Copies ◽  
Xenopus Egg ◽  
Pore Complexes ◽  
Xenopus Egg Extracts

Transport across the nuclear envelope (NE) is mediated by nuclear pore complexes (NPCs). These structures are composed of various subcomplexes of proteins that are each present in multiple copies and together establish the eightfold symmetry of the NPC. One evolutionarily conserved subcomplex of the NPC contains the nucleoporins Nup53 and Nup155. Using truncation analysis, we have defined regions of Nup53 that bind to neighboring nucleoporins as well as those domains that target Nup53 to the NPC in vivo. Using this information, we investigated the role of Nup53 in NE and NPC assembly using Xenopus egg extracts. We show that both events require Nup53. Importantly, the analysis of Nup53 fragments revealed that the assembly activity of Nup53 depleted extracts could be reconstituted using a region of Nup53 that binds specifically to its interacting partner Nup155. On the basis of these results, we propose that the formation of a Nup53–Nup155 complex plays a critical role in the processes of NPC and NE assembly.

scholarly journals In Vivo Dynamics of Drosophila Nuclear Envelope Components

2008 ◽  
Vol 19 (9) ◽  
pp. 3652-3666 ◽  
Author(s):  
Katerina R. Katsani ◽  
Roger E. Karess ◽  
Nathalie Dostatni ◽  
Valérie Doye
Keyword(s):  
Nuclear Envelope ◽  
Mammalian Cells ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Checkpoint Proteins ◽  
Early Anaphase ◽  
Associated Proteins ◽  
Pore Complexes ◽  
Drosophila Cells

Nuclear pore complexes (NPCs) are multisubunit protein entities embedded into the nuclear envelope (NE). Here, we examine the in vivo dynamics of the essential Drosophila nucleoporin Nup107 and several other NE-associated proteins during NE and NPCs disassembly and reassembly that take place within each mitosis. During both the rapid mitosis of syncytial embryos and the more conventional mitosis of larval neuroblasts, Nup107 is gradually released from the NE, but it remains partially confined to the nuclear (spindle) region up to late prometaphase, in contrast to nucleoporins detected by wheat germ agglutinin and lamins. We provide evidence that in all Drosophila cells, a structure derived from the NE persists throughout metaphase and early anaphase. Finally, we examined the dynamics of the spindle checkpoint proteins Mad2 and Mad1. During mitotic exit, Mad2 and Mad1 are actively imported back from the cytoplasm into the nucleus after the NE and NPCs have reformed, but they reassociate with the NE only later in G1, concomitantly with the recruitment of the basket nucleoporin Mtor (the Drosophila orthologue of vertebrate Tpr). Surprisingly, Drosophila Nup107 shows no evidence of localization to kinetochores, despite the demonstrated importance of this association in mammalian cells.

Caspase-dependent proteolysis of integral and peripheral proteins of nuclear membranes and nuclear pore complex proteins during apoptosis

1999 ◽  
Vol 112 (11) ◽  
pp. 1743-1753 ◽  
Author(s):  
B. Buendia ◽  
A. Santa-Maria ◽  
J.C. Courvalin
Keyword(s):  
Nuclear Envelope ◽  
Caspase 3 ◽  
Lymphoid Cells ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Lamin B ◽  
Marker Proteins ◽  
Caspase 6 ◽  
Pore Complexes

We have studied the fate of the nuclear envelope (NE) in different human cells committed to apoptosis by different chemical agents. Using a battery of antibodies against marker proteins of the three domains of the nuclear envelope, namely lamin B (LB) for the lamina, transmembrane proteins LBR and LAP2 for the inner nuclear membrane, and nucleoporins p62, Nup153 and gp210 for the nuclear pore complexes (NPCs), we observed a selective and conserved cleavage of LB, LAP2 and Nup153. In lymphoid cells, the rate of cleavage of these markers was independent of the apoptosis inducing agent, actinomycin D or etoposide, and more rapid than in attached epithelial cells. While lamin B is cleaved by caspase 6, the protease responsible for the cleavage of LAP2 and Nup153 was probably caspase 3, since (1) cleavage of both proteins was specifically prevented by in vivo addition of caspase 3 inhibitor Ac-DEVD-CHO and (2) consensus sites for these caspases are present in both proteins. As LB, LAP2 and Nup153 are exposed at the inner face of the nuclear envelope and all interact with chromatin, we suggest that their cleavage allows both the detachment of NE from chromatin and the clustering of NPCs in the plane of the membrane, two conserved morphological features of apoptosis observed in this study.

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 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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